JP2008013628A - Cellulose acylate composition, cellulose acylate film and method for producing the same, polarizing plate, optical compensation film, antireflection film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film having good surface properties and very few foreign bodies, and capable of suppressing image unevenness on the display screen, generated when built in a display device, and visibility change due to moisture. <P>SOLUTION: The cellulose acylate film is produced by melt-flowing a composition containing 0.01-3 mass% lactone-based compound represented by formula (II) based on cellulose acylate having a prescribed substitution degree (wherein, R<SP>1</SP>-R<SP>4</SP>are H, a 1-20C alkyl, a 7-20C aralkyl or a 6-15C aryl). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose acylate film excellent in thermal stability and a method for producing the same. The present invention also relates to a cellulose acylate composition used for the production of the cellulose acylate film, a polarizing plate using the cellulose acylate film, an optical compensation film, an antireflection film, and a liquid crystal display device.

  Conventionally, when producing a cellulose acylate film used in a liquid crystal display device, the cellulose acylate is dissolved in a chlorinated organic solvent such as dichloromethane, and this is cast on a substrate and dried to form a film. The solution casting method is mainly implemented. Among chlorinated organic solvents, dichloromethane is preferably used because it is a good solvent for cellulose acylate, has a low boiling point (about 40 ° C.), and can be easily dried in a film forming process and a drying process. On the other hand, in recent years, it has been strongly demanded to suppress discharge of organic solvents such as chlorinated organic solvents from the viewpoint of environmental conservation. For this reason, a more strict closed system is adopted to prevent the organic solvent from leaking from the manufacturing process, or even if the organic solvent leaks from the film forming process, the organic solvent is adsorbed through the gas absorption tower before it is released to the outside air. Measures are taken so that the organic solvent is hardly discharged by performing a process such as burning with thermal power or decomposing with an electron beam. However, even if these measures were taken, further non-emission was not achieved, so further improvement was required.

Therefore, as a film forming method that does not use an organic solvent, a method of melt-forming cellulose acylate has been developed (see, for example, Patent Documents 1 and 2). In this method, the melting point is lowered to facilitate film formation by elongating the carbon chain of the ester group of cellulose acylate. Specifically, melt film formation is enabled by changing the cellulose acetate used conventionally to cellulose propionate, cellulose butyrate, or the like. The cellulose acylate film obtained in this way has an advantage that it can provide a retardation film or the like in which the visual field characteristics are unlikely to change due to a change in humidity when used as a substrate. Furthermore, as a method for producing a cellulose acylate film comprising a step of melting cellulose acylate and a step of casting, an ester comprising cellulose acylate having a water content of 3.0% or less, a polyhydric alcohol and a monovalent carboxylic acid 1 to 30% by mass of at least one of a plasticizer and an ester plasticizer comprising a polyvalent carboxylic acid and a monohydric alcohol with respect to the cellulose ester, and at least one of a hindered phenol antioxidant and a hindered amine photo compound A melt film-forming method has been developed in which a mixture containing 0.01 to 5% by mass of cellulose ester is heated and melted and cast at a temperature of 150 to 300 ° C. (for example, patents) Reference 3). It is described that the cellulose acylate film produced by this method can be improved in optical characteristics, dimensional stability and the like by being incorporated in a liquid crystal display device.
Japanese National Patent Publication No. 6-501040 JP 2000-352620 A JP 2006-123513 A

  However, it has been found that the cellulose acylate film melt-formed in accordance with the description of the examples in these documents has a poor surface shape. In particular, the cellulose acylate films produced according to the examples of Patent Documents 2 and 3 were significantly deteriorated in surface condition. In addition, when a polarizing plate is produced using the cellulose acylate film thus obtained and incorporated into a liquid crystal display device, problems such as a decrease in luminance due to a large number of foreign matters due to poor surface condition and high haze occur. It became clear that the improvement was at a necessary level. Such a failure is particularly significant when the polarizing plate is incorporated into a large-sized liquid crystal display panel of 15 inches or more, and has been a big problem.

  In order to solve these problems of the prior art, the present invention reduces the number of foreign matters by suppressing the deterioration of the surface condition of a melt-formed film, and causes image unevenness on a display screen that occurs when the film is incorporated in a liquid crystal display device. Another object is to provide a cellulose acylate film capable of suppressing changes in visibility over time. Another object of the present invention is to provide a cellulose acylate composition that is effectively used when producing the cellulose acylate film. Another object of the present invention is to provide a polarizing plate, an optical compensation film, an antireflection film, and a liquid crystal display device exhibiting excellent durability.

  The inventors of the present invention have found that the surface defects of cellulose acylate that has been conventionally melt-formed include the composition of cellulose acylate, retention during the melt film-forming process (for example, retention during filtration film formation), We thought that this was caused by high temperature operation up to the membrane, and we worked on this improvement. As a result, by using a combination of cellulose acylate having a specific substitution degree and a lactone compound having a specific structure, it is possible to remarkably improve the surface shape of the melt-formed cellulose acylate film. I found it. In addition to the above lactone compound, a phenol compound having a molecular weight of 500 or more and at least one selected from the group consisting of a phosphite compound and a thioether compound having a molecular weight of 500 or more are used in combination. It has also been found that the surface shape of the cellulose acylate resin during molding can be further synergistically improved.

  Surprisingly, it has also been found that the number of foreign matters in a melt-formed cellulose acylate film can be significantly reduced by using a lactone compound according to the present invention.

  The present invention has been provided based on the above findings, and the configuration thereof is as described below.

(Aspect 1)
Cellulose acylate satisfying the following formulas (S-1) to (S-3) and at least one lactone compound represented by the following general formula (II) are 0.01 to A cellulose acylate composition containing 3% by mass.
Formula (S-1) 2.5 ≦ X + Y ≦ 3.0
Formula (S-2) 0 ≦ X ≦ 2.2
Formula (S-3) 0.8 ≦ Y ≦ 3.0
(In the formula, X represents the substitution degree of the acetyl group to the hydroxyl group of cellulose, and Y represents the total substitution degree of the acyl group having 3 to 22 carbon atoms to the hydroxyl group of cellulose.)

（式中Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立して、水素原子、炭素数１〜２０のアルキル基、炭素数７〜２０のアラルキル基または炭素数６〜１５のアリール基を示す。）

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. Show.)

(Aspect 2)
The cellulose acylate comprises at least one selected from the group consisting of a phosphite compound having a molecular weight of 500 or more and a thioether compound having a molecular weight of 500 or more, and a phenol compound having a molecular weight of 500 or more. The cellulose acylate composition according to (Aspect 1), which is contained in an amount of 0.01 to 3% by mass.

(Aspect 3)
The cellulose acylate composition according to (Aspect 1) or (Aspect 2), comprising 0.1 to 20% by mass of a plasticizer or ultraviolet absorber having a molecular weight of 500 or more based on cellulose acylate.

(Aspect 4)
The cellulose acylate composition according to any one of (Aspects 1 to 3), which is in a pellet form.

(Aspect 5)
A method for producing a cellulose acylate film comprising a step of melting and casting a cellulose acylate composition according to any one of (Aspects 1 to 4).

(Aspect 6)
A process for producing a pellet by melting the cellulose acylate composition of any one of (Aspects 1 to 3) at 150 to 240 ° C., melting the pellet, and extruding it from a die at 180 to 240 ° C. A method for producing a cellulose acylate film, comprising:
(Aspect 7)
The cellulose acylate film according to (Aspect 5) or (Aspect 6), comprising a step of casting the cellulose acylate composition and then forming a film by pressing a touch roll at 0.1 to 10 MPa. Manufacturing method.
(Aspect 8)
The method for producing a cellulose acylate film according to any one of (Aspects 5 to 7), comprising a step of stretching 1% to 300% in at least one direction after the film formation.

(Aspect 9)
A cellulose acylate film produced by the production method according to any one of (Aspects 5 to 8).

(Aspect 10)
0.01-3 masses of the cellulose acylate satisfying the above formulas (S-1) to (S-3) and at least one of the lactone compounds represented by the general formula (II) with respect to the cellulose acylate. %, And the residual solvent amount is 0.01% by mass or less.
(Aspect 11)
The cellulose acylate film is at least one selected from the group consisting of a phosphite compound having a molecular weight of 500 or more and a thioether compound having a molecular weight of 500 or more, and a phenolic compound having a molecular weight of 500 or more; Is contained in an amount of 0.01 to 3% by mass with respect to the cellulose acylate (Aspect 10).

(Aspect 12)
The cellulose acylate film according to any one of (Aspects 9 to 11), wherein the film thickness is 20 μm to 300 μm.
(Aspect 13)
The cellulose acylate according to any one of (Aspects 9 to 12), wherein the front retardation (Re) is 0 to 300 nm and the absolute value of retardation (Rth) in the thickness direction is 0 to 700 nm. Rate film.
(Aspect 14)
The cellulose acylate film according to any one of (Aspects 9 to 13), wherein the visible light transmittance is 90% or more and the haze is 0.01 to 1.5%.

(Aspect 15)
The cellulose acylate film according to any one of (Aspects 9 to 14), wherein the following formulas (A-1) and (A-2) are satisfied.
Formula (A-1) 0 ≦ | Re (700) −Re (400) | ≦ 15 nm
Formula (A-2) 0 ≦ | Rth (700) −Rth (400) | ≦ 35 nm
(In the formula, Re (400) and Re (700) represent front retardation (Re) at wavelengths of 400 nm and 700 nm of the cellulose acylate film, respectively, and Rth (400) and Rth (700) represent the cellulose Represents the retardation (Rth) in the thickness direction of the acylate film at wavelengths of 400 nm and 700 nm.)
(Aspect 16)
The cellulose acylate film according to any one of (Aspects 9 to 15), wherein the thickness unevenness is 0 to 5 μm.

(Aspect 17)
A polarizing plate comprising at least one layer of the cellulose acylate film of any one of (Aspects 9 to 16) laminated on a polarizer.
(Aspect 18)
An optical compensation film comprising the cellulose acylate film of any one of (Aspects 9 to 16).
(Aspect 19)
An antireflection film using the cellulose acylate film of any one of (Aspects 9 to 16).
(Aspect 20)
At least selected from the group consisting of the cellulose acylate film of any one of (Aspects 9 to 16), the polarizing plate of (Aspect 17), the optical compensation film of (Aspect 18), and the antireflection film of (Aspect 19). A liquid crystal display device using one.

  The cellulose acylate film of the present invention has a good surface shape, an extremely small number of foreign matters, and can suppress changes in visibility due to image unevenness and humidity generated on a display screen when incorporated in a liquid crystal display device. . Further, the cellulose acylate film of the present invention can provide a polarizing plate, an optical compensation film and an antireflection film having weather resistance over time, particularly excellent durability under a high temperature environment. Furthermore, the liquid crystal display device manufactured by incorporating the cellulose acylate film of the present invention can suppress display unevenness, changes in optical characteristics due to humidity or image color.

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

<< Cellulose Acylate Composition >>
The cellulose acylate composition of the present invention comprises at least one of cellulose acylate satisfying the following formulas (S-1) to (S-3) and a lactone compound represented by the following general formula (II). It is contained by 0.01 to 3% by mass with respect to the rate.
Formula (S-1) 2.5 ≦ X + Y ≦ 3.0
Formula (S-2) 0 ≦ X ≦ 2.2
Formula (S-3) 0.8 ≦ Y ≦ 3.0
(In the formula, X represents the substitution degree of the acetyl group to the hydroxyl group of cellulose, and Y represents the total substitution degree of the acyl group having 3 to 22 carbon atoms to the hydroxyl group of cellulose.)

（式中Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立して、水素原子、炭素数１〜２０のアルキル基、炭素数７〜２０のアラルキル基または炭素数６〜１５のアリール基を示す。）

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. Show.)

  The cellulose acylate composition of the present invention may contain, in addition to the above cellulose acylate and the lactone compound represented by the above general formula (II), a plasticizer, an ultraviolet absorber and the like as necessary. Good. Hereinafter, each component contained in the cellulose acylate composition of the present invention will be described in detail.

[Cellulose acylate]
First, the cellulose acylate used in the present invention will be described. The cellulose acylate in the present invention satisfies the following substitution degree.
Formula (S-1) 2.5 ≦ X + Y ≦ 3.0
Formula (S-2) 0 ≦ X ≦ 2.2
Formula (S-3) 0.8 ≦ Y ≦ 3.0

  In the formula, X represents the degree of substitution of the acetyl group with respect to the hydroxyl group of cellulose, and Y represents the total degree of substitution of the acyl group having 3 to 22 carbon atoms with respect to the hydroxyl group of cellulose.

  The “degree of substitution” in the present specification means the total of the ratio of substitution of hydrogen atoms of hydroxyl groups at the 2-position, 3-position and 6-position of cellulose. When the hydrogen atoms of all hydroxyl groups at the 2nd, 3rd and 6th positions are substituted with acyl groups, the degree of substitution is 3. The C3-C22 acyl group represented by the substituent Y of the cellulose ester of the present invention may be either an aliphatic acyl group or an aromatic acyl group. When the acyl group of the cellulose acylate in the present invention is an aliphatic acyl group, the number of carbon atoms is preferably 3-18, more preferably 3-12, and the number of carbons is 3-8. It is particularly preferred. Examples of these aliphatic acyl groups include an alkylcarbonyl group, an alkenylcarbonyl group, and an alkynylcarbonyl group. When the acyl group is an aromatic acyl group, the carbon number is preferably 6-22, more preferably 6-18, and particularly preferably 6-12. Each of these acyl groups may further have a substituent.

  Examples of the preferred acyl group include propionyl group, butyryl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group , Isobutyryl group, pivaloyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthalenecarbonyl group, phthaloyl group, cinnamoyl group and the like. Among these, more preferred are propionyl, butyryl, dodecanoyl, octadecanoyl, pivaloyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like.

  In particular, the acyl group in Y is preferably an aliphatic acyl group having 3 to 6 carbon atoms, and is preferably an acyl group selected from the group consisting of a propionyl group, a butyryl group, a pentanoyl group and a hexanoyl group. A more preferable acyl group in Y is an acyl group selected from the group consisting of a propionyl group and a butyryl group. The acyl group in Y constituting the ester of cellulose acylate in the present invention may be a single species or a plurality of species. In the present invention, the substitution degree distribution of hydroxyl groups at the 2-position, 3-position and 6-position of cellulose is not particularly limited.

The cellulose acylate in the present invention is preferably a cellulose acylate that satisfies the following formulas (S-4) to (S-6).
Formula (S-4) 2.6 ≦ X + Y ≦ 3.0
Formula (S-5) 0 ≦ X ≦ 2.0
Formula (S-6) 1.0 <= Y <= 3.0

As the cellulose acylate in the present invention, it is particularly preferable to use a cellulose acylate that satisfies the following formulas (S-7) to (S-9).
Formula (S-7) 2.65 ≦ X + Y ≦ 2.97
Formula (S-8) 0.1 ≦ X ≦ 1.8
Formula (S-9) 1.1 ≦ Y ≦ 3.0

  As the cellulose raw material for synthesizing the cellulose acylate used in the present invention, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used.

  Regarding the method for synthesizing cellulose acylate used in the present invention, paragraph numbers [0018] to [0033] of JP-A-2006-45500, paragraph numbers [0014] to [0030] of JP-A-2006-45501, This is described in detail in paragraph numbers [0018] to [0023] of Japanese Patent Publication No. 2006-45502. It is also described in detail in pages 7 to 12 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention and Innovation). These synthetic methods can be preferably used. For specific procedures of cellulose acylate preferably used in the present invention, reference can be made to Synthesis Examples 1 and 2 described later. In order to reduce the foreign matter in the cellulose acylate of the present invention to the maximum, it is preferable to remove it from the raw material, and it can be removed using a filtration method in the raw material synthesis stage.

(Filtration)
In order to remove or reduce unreacted substances, hardly soluble salts, and other foreign matters in the cellulose acylate in the present invention, a reaction solution containing cellulose acylate in any of the steps from the acylation step to the reprecipitation step Is preferably filtered. The retained particle size of the filter used for filtration is preferably 0.1 μm to 50 μm, more preferably 0.5 μm to 40 μm, and particularly preferably 1 μm to 30 μm. When the retained particle size of the filter is smaller than 0.1 μm, the filtration pressure is remarkably increased, and industrial production is substantially difficult. Further, when the retained particle size is larger than 40 μm, the foreign matter may not be sufficiently removed. Moreover, you may repeat filtration twice or more.

  The material of the filter is not particularly limited as long as it is not adversely affected by the solvent. Preferred examples include a cellulose filter, a metal filter, a metal sintered filter, a ceramic sintered filter, a Teflon filter (PTFE filter), and a polyether. Examples include a sulfone filter, a polypropylene filter, a polyethylene filter, and a glass fiber filter, and these may be used in combination. Of these, stainless steel metal filters and sintered metal filters are preferred.

  A filter having a charge trapping function can also be preferably used as the filter material. The filter having a charge trapping function is a filter having a function of electrically trapping and removing charged foreign substances, and usually a filter medium provided with a charge is used. As examples of such a filter, those described in JP-T-4-504379, JP-A 2000-212226 and the like can be selected.

Further, as a filter aid, a method of performing so-called cake filtration in which celite, layered clay mineral (preferably talc, mica, kaolinite, etc.) and the like are mixed in a cellulose acylate solution and filtered is also preferably used. .
For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Degree of polymerization)
The number average degree of polymerization of the cellulose acylate preferably used in the present invention is preferably 110 to 350, more preferably 120 to 300, and still more preferably 130 to 250. In the present invention, the number average degree of polymerization is measured by a method using gel permeation chromatography (GPC) described later.
In the present invention, a cellulose acylate having a mass average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5 by GPC is preferably used, more preferably 1.5 to 5.0, Preferably it is 1.5-4.5, Most preferably, the cellulose acylate of 1.5-3.5 is used preferably. The obtained cellulose acylate is preferably stored in a low temperature and dark place so that the storage is less affected by the environment. Further, it is more preferable to store in a moisture-proof bag made of a prevention material such as aluminum, a SUS drum or a container for storage.

  These cellulose acylates may be used alone or in combination of two or more. Further, a polymer component other than cellulose acylate may be appropriately mixed. The polymer component to be mixed is preferably one having excellent compatibility with cellulose acylate, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and 92% or more. More preferably it is.

[Lactone compounds]
The cellulose acylate composition of the present invention contains at least one lactone compound represented by the following general formula (II). The lactone compound is preferably added before or when the cellulose acylate is heated and melted. By adding the lactone compound in the present invention, it is possible to obtain the effect of improving the film surface shape and reducing the number of foreign substances.

（式中Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立して、水素原子、炭素数１〜２０のアルキル基、炭素数７〜２０のアラルキル基または炭素数６〜１５のアリール基を示す。）

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. Show.)

  In the general formula (II), the alkyl group having 1 to 20 carbon atoms may be a linear or branched alkyl group. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, 2-ethylbutyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group Tetradecyl group, octadecyl group, eicosyl group and the like.

  In the general formula (II), examples of the aralkyl group having 7 to 20 carbon atoms include benzyl group, 2,6-ditertiarybutyl-4-methylbenzyl group, phenethyl group, phenylpropyl group, naphthylmethyl group and 2-phenylisopropyl. Groups and the like.

  In general formula (II), examples of the aryl group having 6 to 15 carbon atoms include a phenyl group, a tolyl group, and a naphthyl group.

In general formula (II), R ¹ and R ² are preferably a combination of a hydrogen atom and an aryl group having 7 to 20 carbon atoms. Among them, a combination of a hydrogen atom and an aryl group having 8 to 20 carbon atoms is preferable, a combination of a hydrogen atom and an aryl group having 8 to 18 carbon atoms is more preferable, and a hydrogen atom and a 3,4-dimethylphenyl group The combination of is particularly preferable.

In general formula (II), R ³ and R ⁴ are preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 2 to 20 carbon atoms, and an alkyl group having 3 to 20 carbon atoms. Is more preferable, and a tert-butyl group is particularly preferable.

  The lactone compound in the present invention is contained in an amount of 0.01 to 3% by mass with respect to the cellulose acylate. When the content of the lactone compound is less than 0.01% by mass, the effect of improving the surface shape and reducing the foreign matter cannot be obtained. When the content exceeds 3% by mass, the Tg of the cellulose acylate is decreased, and the physical properties are reduced. May decrease. The content of the lactone compound is preferably 0.02 to 2% by mass and more preferably 0.05 to 1.0% by mass with respect to the cellulose acylate. When the amount of the lactone compound used is within the above range, a cellulose acylate film (including a sheet-like material) excellent in hue can be obtained by imparting sufficient molding heat resistance to the cellulose acylate.

  Specific examples of the lactone compound represented by the following formula (II) include the following compounds (exemplary compounds (a) -1 to (a) -49).

  Commercially available products can be used as these lactone compounds, for example, HP-136 (manufactured by Ciba Specialty Chemicals) can be used. These lactone compounds can be used alone or in combination.

[Other ingredients]
(Compound with a molecular weight of 500 or more in the present invention)
In the present invention, at least one selected from the group consisting of a phenolic compound having a molecular weight of 500 or more, a phosphite compound, and a thioether compound is used as at least one of cellulose acylate and lactone compound (these are referred to as “the present invention”). Are preferably added to the cellulose acylate composition, and the phosphite compound having a molecular weight of 500 or more and the thioether compound having a molecular weight of 500 or more. It is more preferable to use at least one selected and a phenolic compound having a molecular weight of 500 or more. Thereby, the synergistic effect of the surface shape improvement at the time of the shaping | molding process of a cellulose acylate resin and a foreign material reduction is acquired. Since these compounds need not volatilize even at high temperatures, the molecular weight is 500 or more, preferably 500 to 3000, more preferably 530 to 3000, and particularly preferably 600 to 2000. Moreover, since it is preferable that it does not volatilize at high temperature, it is preferable that the mass reduction | decrease amount when it heats at 220 degreeC for 30 minutes in air is 20 mass% or less, It is more preferable that it is 15 mass% or less. The content is more preferably at most 5 mass%, particularly preferably at most 5 mass%.

  The amount of the compound having a molecular weight of 500 or more in the present invention is preferably 0.01 to 3% by mass, more preferably 0.02 to 2.5% by mass, and more preferably 0 to 0% by mass with respect to the cellulose acylate. It is 0.03-1.0 mass%, Most preferably, it is 0.04-0.7 mass%, Most preferably, it is 0.05-0.6 mass%. The ratio between the content of the lactone compound and the total content of the compounds having a molecular weight of 500 or more in the present invention is not particularly limited, but is preferably 1/30 to 1/1 (parts by mass), more preferably 1/20. Is 1/1/1 (part by mass), more preferably 1/15 to 1/2 (part by mass), and particularly preferably 1/10 to 1/2 (part by mass). The ratio of the content of the phenolic compound and the content of the phosphite compound or thioether compound is not particularly limited, but is preferably 1/10 to 10/1 (parts by mass), more preferably. Is 1/5 to 5/1 (parts by mass), more preferably 1/3 to 3/1 (parts by mass), and particularly preferably 1/3 to 2/1 (parts by mass). Lactone-based, phenol-based, phosphite-based, thioether-based, and if necessary amine-based, the amount of each compound added is within the above range, and there is no particular limitation on the amount ratio. In the present invention, if a lactone compound is used, even if a phosphite ester compound or a phenol compound is added, the cellulose acylate molecular weight is hardly changed by coloring or heating. However, if the phenolic type is too much, the color becomes conspicuous in the resin composition, and if the phosphite type is too much, the cellulose acylate is not preferable because it gels or decomposes.

  In the present invention, it is preferable to add at least one of the compounds having a molecular weight of 500 or more in the present invention to the cellulose acylate composition before or at the time of heat melting of the cellulose acylate. These include anti-oxidation of cellulose acylate composition, capture of acid generated by decomposition, suppression or prohibition of decomposition reaction due to radical species caused by light or heat, etc. It is useful for suppressing the generation of volatile components due to alterations such as molecular weight reduction and decomposition of materials.

(Phenolic compounds)
Any known phenolic compound can be used as the phenolic compound having a molecular weight of 500 or more. Preferable phenolic compounds include hindered phenolic compounds. In particular, it is preferable to have a substituent at a site adjacent to the hydroxyphenyl group. In this case, the substituent is preferably a substituted or unsubstituted alkyl group having 1 to 22 carbon atoms, such as a methyl group, an ethyl group, or a propionyl group. , Isopropionyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, tert-pentyl group, hexyl group, octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, isononyl group, dodecyl Group, tert-dodecyl group, tridecyl group, tert-tridecyl group and the like. Among these, methyl group, ethyl group, propionyl group, isopropionyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, tert-pentyl group, hexyl group, octyl group, isooctyl group, 2- Ethylhexyl group is more preferred. More preferred are propionyl group, isopropionyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group and tert-pentyl group.
Specific examples of the phenolic compound include the following compounds, but the phenolic compound that can be used in the present invention is not limited to these specific examples.

(PH-1)
n-Octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate (molecular weight 531)
(PH-2)
Tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane (molecular weight 1178)
(PH-3)
Tris- (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (molecular weight 784)
(PH-4)
Triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (molecular weight 588)
(PH-5)
3,9-bis- {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxa Spiro [5.5] undecane (molecular weight 741)
(PH-6)
1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene (molecular weight 775)
(PH-7)
1,1,3-tris (5-di-tert-butyl-4-hydroxy-2-methylphenyl) butane (molecular weight 545)
(PH-8)
1,6-hexanediol-bis {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate} (molecular weight 639)
(PH-9)
2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (molecular weight 589)
(PH-10)
1,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate] (molecular weight 643)
(PH-11)
N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide) (molecular weight 637)
(PH-12)
Bis (ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate) calcium (molecular weight 695)

  These materials are readily available as commercial products and are sold by the following manufacturers. For example, from Ichiba Specialty Chemicals, Irganox 1076, Irganox 1010, Irganox 3113, Irganox 245, Irganox 1135, Irganox 1330, Irganox 259, Irganx 565, Irganx 565, Ir3510 Moreover, it can obtain from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-20, ADK STAB AO-70, and ADK STAB AO-80. Furthermore, it can be obtained from Sumitomo Chemical Co., Ltd. as Sumilizer BP-76, Sumilizer BP-101, Sumilizer GA-80. In addition, it is also possible to obtain as Sinox 326M and Sinox 336B from Sipro Kasei Co., Ltd.

(Phosphite compound)
Next, a phosphite compound having a molecular weight of 500 or more that can be added to cellulose acylate in the present invention will be described.
As the phosphite compound having a molecular weight of 500 or more that can be used in the present invention, any conventionally known phosphite compound can be used. Examples of the phosphite compound that can be used in the present invention include compounds described in JP-A No. 2004-182979, [0023] to [0039]. Specific examples of the phosphite ester compounds include JP-A-51-70316, JP-A-10-306175, JP-A-57-78431, JP-A-54-157159, JP-A-5-157159. The compounds described in JP-A No. 55-13765 can also be mentioned. Furthermore, as other compounds, materials described in detail on pages 17 to 22 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention) can also be mentioned. .

Since the phosphite ester compound has a phenol ester and can maintain stability at high temperature, at least one substituent is preferably an aromatic ester group. Further, the phosphite compound is preferably a triester, and it is desirable that impurities of phosphoric acid, monoester and diester are not mixed. When these impurities are present, the content is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly 2% by mass or less.
Preferable specific examples of the phosphite compound include the following compounds, but the phosphite compound that can be used in the present invention is not limited thereto.

(PF-1)
Trisnonyl phenyl phosphite (molecular weight 689)
(PF-2)
Tris (2,4-di-tert-butylphenyl) phosphite (molecular weight 647)
(PF-3)
Distearyl pentaerythritol diphosphite (molecular weight 733)
(PF-4)
Bis (2,4-di-tert-butylphenyl) pentaerythritol phosphite (molecular weight 605)
(PF-5)
Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (molecular weight 633)
(PF-6)
2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite (molecular weight 529)
(PF-7)
Tetrakis (2,4-di-tert-butylphenyl) -4,4-biphenylene-di-phosphite (molecular weight 517)

  These are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB 1178, 2112, PEP-8, PEP-24G, PEP-36G, HP-10, and Clariant as Sandostab P-EPQ. It is available. Furthermore, compounds having phenol and phosphite in the same molecule are also preferably used. Specific examples of the compound having the phenol and the phosphite in the same molecule include the following. These compounds are further described in detail in JP-A-10-273494, and examples of such compounds are shown, but the stabilizers that can be used in the present invention are not limited thereto. As a typical commercial product, Sumitizer GP can be mentioned from Sumitomo Chemical Co., Ltd.

(FFP-1)
2,10-Dimethyl-4,8-di-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1 , 3,2] dioxaphosphocin (molecular weight 632)
(FFP-2)
2,4,8,10-tetra-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propoxy] dibenzo [d, f] [1,3,2] Dioxaphosphepine (molecular weight 702)

(FFP-3)
2,4,8,10-Tetra-tert-pentyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propoxy] -12-methyl-12H-dibenzo [d, g] [1,3,2] dioxaphosphocin (molecular weight 787)
(FFP-4)
2,10-Dimethyl-4,8-di-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -12H-dibenzo [d, g] [ 1,3,2] dioxaphosphocin (molecular weight 646)
(FFP-5)
2,4,8,10-Tetra-tert-pentyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -12-methyl-12H-dibenzo [d, g ] [1,3,2] dioxaphosphocin (molecular weight 801)
(FFP-6)
2,4,8,10-tetra-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -dibenzo [d, f] [1,3 2] Dioxaphosphepine (molecular weight 716)
(FFP-7)
2,10-Dimethyl-4,8-di-tert-butyl-6- (3,5-di-tert-butyl-4-hydroxybenzoyloxy) -12H-dibenzo [d, g] [1,3,2 Dioxaphosphocin (molecular weight 618)
(FFP-8)
2,4,8,10-tetra-tert-butyl-6- (3,5-di-tert-butyl-4-hydroxybenzoyloxy) -12-methyl-12H-dibenzo [d, g] [1,3 , 2] dioxaphosphocin (molecular weight 717)
(FFP-9)
2,4,8,10-tetra-tert-butyl-6- [3- (3-methyl-4-hydroxy-5-tert-butylphenyl) propoxy] dibenzo [d, f] [1,3,2] Dioxaphosphepine (molecular weight 660)
(FFP-10)
2,10-Dimethyl-4,8-di-tert-butyl-6- [3- (3-methyl-4-hydroxy-5-tert-butylphenyl) propoxy] -12H-dibenzo [d, g] [1 , 3,2] dioxaphosphocin (molecular weight 590)
(FFP-11)
2,4,8,10-tetra-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1,3 , 2] dioxaphosphocin (molecular weight 717)
(FFP-12)
2,10-diethyl-4,8-di-tert-butyl-6- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1 , 3,2] dioxaphosphocin (molecular weight 661)
(FFP-13)
2,4,8,10-Tetra-tert-butyl-6- [2,2-dimethyl-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -dibenzo [d, f] [1,3,2] dioxaphosphepine (molecular weight 688)
(FFP-14)
6- [3- (3-tert-Butyl-4-hydroxy-5-methyl) propoxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1,3,2] dioxa Phosfepine (molecular weight 660)

(Thioether compounds)
Next, a thioether compound having a molecular weight of 500 or more that can be added to cellulose acylate in the present invention will be described.
As the thioether compound, a known thioether compound having a molecular weight of 500 or more can be arbitrarily used.
Specific examples of preferred thioether compounds include the following compounds, but preferred examples that can be used in the present invention are not limited thereto.

(TE-1)
Dilauryl-3,3-thiodipropionate (molecular weight 515)
(TE-2)
Dimyristyl-3,3-thiodipropionate (molecular weight 571)
(TE-3)
Distearyl-3,3-thiodipropionate (molecular weight 683)
(TE-4)
Pentaerythritol tetrakis (3-laurylthiopropionate) (molecular weight 1162)

  These are commercially available from Sumitomo Chemical Co., Ltd. as Sumilizer TPL, TPM, TPS, TDP. It is also available from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-412S.

(Other compounds)
In the present invention, compounds useful for melt film formation of cellulose acylate other than phenolic compounds having a molecular weight of 500 or more, phosphite compounds having a molecular weight of 500 or more, and thioether compounds having a molecular weight of 500 or more may be used in combination. I do not care. Examples of such a compound include a tin-based compound, and any known tin-based compound can be used. Specific examples of preferable tin-based compounds include octyl tin maleate polymer, monostearyl tin tris (isooctyl thioglycolate), and dibutyl tin dilaurate.

  An amine compound can also be used, and in this case, any known amine compound can be used. Specific examples of preferred amine compounds include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-[(2H-benzotriazol-2-yl) phenol]], Tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, phenyl-β-naphthylamine, N, N′-di-sec-butyl-p-phenylene Diamine, N, N'-diphenyl-p-phenylenediamine, N-phenyl-N'-cyclohexyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, 4-benzoyloxy-2,2 , 6,6-tetramethylpiperazine, bis (2,2,6,6-tetramethyl-4-piperidine) sebacate, bis [(1,2,2,6,6- Pentamethyl-4-piperidinyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butylmalonate, tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) Examples include 1,2,3,4-butane-tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butane-tetracarboxylate, and the like. These are commercially available from Asahi Denka as ADK STAB LA-57, LA-52, LA-67, LA-62, LA-77, and TINUVIN 765, 144 from Ciba Specialty Chemicals. .

(Acid scavenger)
Since cellulose acylate is accelerated by acid at high temperatures, the cellulose acylate film of the present invention preferably contains an acid scavenger.

  Any acid scavenger useful in the present invention can be used without limitation as long as it is a compound that reacts with an acid to inactivate the acid, and is described in U.S. Pat. No. 4,137,201. Compounds having an epoxy group are preferred. Epoxy compounds as such acid scavengers are known in the art and are derived by condensation of various polyglycol diglycidyl ethers, particularly about 8-40 moles of ethylene oxide per mole of polyglycol. Glycol, diglycidyl ethers of glycerol, metal epoxy compounds (such as those conventionally used in and with vinyl chloride polymer compositions), epoxidized ether condensation products, diphenols of bisphenol A Glycidyl ether (i.e., 4,4'-dihydroxydiphenyldimethylmethane), epoxidized unsaturated fatty acid ester (especially an ester of an alkyl of about 4 to 2 carbon atoms of a fatty acid of 2 to 22 carbon atoms (e.g. butyl Epoxy steerer )), And epoxidized vegetable oils and other unsaturated natural oils, which may be represented and exemplified by compositions of various epoxidized long chain fatty acid triglycerides and the like (eg, epoxidized soybean oil) These are referred to as glycerides or unsaturated fatty acids, which generally contain 12 to 22 carbon atoms). Moreover, EPON 815C can also be preferably used as a commercially available epoxy group-containing epoxide resin compound. Furthermore, examples of acid scavengers that can be used other than the above include oxetane compounds, oxazoline compounds, organic earth salts of alkaline earth metals and acetylacetonate complexes, and paragraphs 68 to 105 of JP-A-5-194788. Is included.

  In the present invention, various additives may be further added to the cellulose acylate composition as necessary. Addition of the additive may be performed at any stage from before preparation of the melt to after preparation. In the present invention, as additives other than the compound having a molecular weight of 500 or more in the present invention, plasticizers, ultraviolet absorbers (UV agents), fine particles, optical modifiers, release agents, surfactants, antistatic agents, flame retardants, lubricants An oil agent or the like can be used.

(Plasticizer)
In the present invention, it is preferable to add a plasticizer to cellulose acylate. Any known plasticizer may be used, but may be a phosphate ester compound, a monosaccharide or a carbohydrate derivative containing 2 to 10 monosaccharide units (hereinafter referred to as “carbohydrate plasticizer”), Carboxylic acid ester compounds, alkylphthalyl alkyl glycolate compounds, polyhydric alcohol fatty acid ester compounds, and the like are preferably used.

The plasticizer used in the present invention is preferably sufficiently low in volatility at high temperatures, and preferably has a molecular weight of 500 to 4,000, more preferably 530 to 3,500, and particularly preferably 550 to 5,000. 3,000. When the molecular weight is 500 or more, heat volatility is large, and when the molecular weight is 4000 or less, a more effective plastic effect can be obtained.
Moreover, the mass reduction | decrease amount at the time of a heating can be used as a volatile parameter | index, for example, it is preferable that the mass reduction | decrease amount when it hold | maintains at 240 degreeC for 1 hour in nitrogen atmosphere is 15 mass% or less. More preferably, it is 10 mass% or less, More preferably, it is 5 mass% or less, Most preferably, it is 3 mass% or less. Thereby, the heat volatilization of the plasticizer can be greatly reduced even under severe conditions (high temperature due to local resin retention and sen insulation) during the melt film-forming process of the cellulose acylate film of the present invention.

  In this invention, a plasticizer may be mix | blended independently and may be used together 2 or more types. The addition amount of the plasticizer is preferably 0.5 to 25% by mass with respect to the cellulose acylate resin. If the addition amount is 0.5% by mass or more, the heat volatility is more easily suppressed, and if the addition amount is 25% by mass or less, the heat distortion temperature of the cellulose acylate is easily maintained. A preferable addition amount is 1 to 20% by mass, more preferably 1 to 15% by mass, and further preferably 1 to 10% by mass.

-Phosphate ester compound-
Examples of the phosphate ester plasticizer that can be used in the present invention include [0027] to [0034] in JP-A-2002-363423, [0027] to [0034] in JP-A-2002-265800, and the like. Non-volatile phosphate compounds described in [0014] to [0040] of Kaikai 2003-155292 can be given as preferred examples.

  Specific examples of the phosphate ester compound (phosphate ester plasticizer) are listed below, but the phosphate ester plasticizer that can be used in the present invention is not limited thereto. These compounds are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB FP-500, ADK STAB FP-600, ADK STAB FP-700, ADK STAB FP-2100, ADK STAB PFR, and the like. It can also be obtained from Ajinomoto Chemical Co., Ltd. as Leoforce BAPP.

-Carbohydrate compound plasticizer-
The carbohydrate-based plasticizer that can be used in the present invention is a monosaccharide or a derivative of a carbohydrate containing 2 to 10 monosaccharide units. (For example, a hydroxyl group, a carboxyl group, an amino group, a mercapto group, etc.) is substituted. Examples of the substituent include an ether group, an ester group, an amide group, and an imide group.

Preferable examples of the carbohydrate plasticizer include the following. However, the carbohydrate-based plasticizer that can be used in the present invention is not limited to these.
Maltose octaacetate, cellobiose octaacetate, sucrose octaacetate, xylose tetrapropionate, glucose pentapropionate, fructose pentapropionate, mannose pentapropionate, galactose pentapropionate, maltose octapropionate, cellobiose octane Propionate, sucrose octapropionate, xylose tetrabenzoate, glucose pentabenzoate, fructose pentabenzoate, mannose pentabenzoate, galactose pentabenzoate, maltose octabenzoate, cellobiose octabenzoate, sucrose octabenzoate, xylitol pentabenzoate, sorbitol hexabenzoate, etc. Especially Masui.

-Other plasticizers-
Other plasticizers include alkyl phthalyl alkyl glycolates, carboxylic acid esters, fatty acid esters of polyhydric alcohols, and the like. It is preferable that the weight loss is within 15% after heating at 240 ° C. for 1 hour. As these plasticizers, it is preferable to use the compounds described in JP-A 2000-265800, [0010] to [0021]. In addition, as the polyhydric alcohol plasticizer that can be specifically used, glycerin ester compounds such as glycerin ester and diglycerin ester, which have good compatibility with cellulose fatty acid esters and a remarkable thermoplastic effect, Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and compounds in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol. As these plasticizers, it is preferable to use compounds described in JP-A-2006-45500, [0039] to [0044].

  The timing of adding these plasticizers to cellulose acylate is not particularly limited as long as it is added at the time of melt film formation. For example, it may be added at the time of cellulose acylate synthesis, may be mixed in advance in cellulose acylate before melting, or preferably formed into a film while being mixed with cellulose acylate during melt film formation. When adding at the time of the synthesis of cellulose acylate, it may be added before or after the precipitation of cellulose acylate, or it may be added when cellulose acylate is dispersed in a solution state. Thereby, a cellulose acylate and an additive can be mixed uniformly.

  In the present invention, if a plasticizer is added to the cellulose acylate composition, the crystal melting temperature (Tm) and melt viscosity of the cellulose acylate can be lowered. Therefore, the melt processing temperature can also be lowered, and the effect of preventing the coloration of the cellulose acylate film in the high temperature melting step can be obtained. By greatly reducing the melt viscosity, the flow of the resin during the melt film-forming process becomes smooth, and the generated die line can be leveled. Moreover, the coloring by heat deterioration can be improved by shortening the filtration residence time.

(UV absorber)
An ultraviolet inhibitor may be added to the cellulose acylate. With respect to the ultraviolet ray inhibitor, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854. 6-118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, There exists description in Unexamined-Japanese-Patent No. 2000-204173 etc. The addition amount is preferably 0.01 to 2% by mass, and more preferably 0.01 to 1.5% by mass, based on the melt (melt) to be prepared.

  The following commercially available products can also be used as these ultraviolet absorbers. As benzotriazoles, TINUBIN P (Ciba Specialty Chemicals), TINUBIN 234 (Ciba Specialty Chemicals), TINUBIN 320 (Ciba Specialty Chemicals), TINUBIN 326 (Ciba Specialty Chemicals) TINUBIN 327 (Ciba Specialty Chemicals), TINUBIN 328 (Ciba Specialty Chemicals), Sumisorb 340 (Sumitomo Chemical), Adekas Type LA-31 (Asahi Denka Kogyo Co., Ltd.), etc. . In addition, as benzophenone-based ultraviolet absorbers, Seasorb 100 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101 (manufactured by Sipro Kasei Co., Ltd.), Seasorb 101S (manufactured by Sipro Kasei Co., Ltd.), Seasorb 102 (manufactured by Sipro Kasei Chemical), Seasorb 103 (Sipro Kasei Co., Ltd.), Adekas Type LA-51 (Asahi Denka Kogyo Co., Ltd.), Chemisorp 111 (Chemipro Kasei Co., Ltd.), UVINUL D-49 (BASF Corp.), and the like. Examples of oxalic acid anilide UV absorbers include TINUBIN 312 (manufactured by Ciba Specialty Chemicals) and TINUBIN 315 (manufactured by Ciba Specialty Chemicals). In addition, as a salicylic acid ultraviolet absorber, Seasorb 201 (manufactured by Sipro Kasei) and Seasorb 202 (manufactured by Sipro Kasei) are marketed, and as a cyanoacrylate ultraviolet absorber, Seasorb 501 (manufactured by Sipro Kasei), UVINUL N-539 (BASF) is available.

(Fine particles)
In the present invention, fine particles may be added to the cellulose acylate composition. Examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound. The average primary particle size of preferable fine particles contained in the cellulose acylate in the present invention is 5 nm to 3 μm, preferably 5 nm to 2.5 μm, and particularly preferably 20 nm to 2.0 μm. The addition amount of the fine particles is preferably 0.005 to 1.0% by mass, more preferably 0.01 to 0.8% by mass, and further preferably 0.02 to 0% with respect to the cellulose acylate. 4% by mass.

Examples of the inorganic compound include SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , V ₂ O ₅ , talc, clay, calcined kaolin, and calcined. Examples thereof include calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. At least one of SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , and V ₂ O ₅ is preferable, and SiO ₂ , TiO are more preferable. _{2, SnO 2, Al 2 O} 3, a ZrO _2.

As the SiO ₂ fine particles, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. As the ZrO ₂ fine particles, for example, commercially available products such as Aerosil R976 and R811 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. Seahoster KE-E10, E30, E40, E50, E50, E70, E150, W10, W30, W50, P10, P30, P50, P100, P150, P250 Products) etc. are also used. Silica microbeads P-400 and 700 (catalyst chemicals Co., Ltd. product) can also be used. SO-G1, SO-G2, SO-G3, SO-G4, SO-G5, SO-G6, SO-E1, SO-E2, SO-E3, SO-E4, SO-E5, SO-E6, SO- It can also be used as C1, SO-C2, SO-C3, SO-C4, SO-C5, SO-C6 (manufactured by Admatechs). Furthermore, silica particles (a powdered water dispersion) 8050, 8070, 8100, and 8150 manufactured by Moritex Corporation can also be used.

  Next, as the fine particles of the organic compound that can be used in the present invention, for example, polymers such as silicone resins, fluororesins, and acrylic resins are preferable, and silicone resins are particularly preferable. The silicone resin preferably has a three-dimensional network structure, such as Tospearl 103, 105, 108, 120, 145, 3120, and 240 (above, manufactured by Toshiba Silicone Co., Ltd.). Commercial products having a trade name can be used.

Further, it is preferable to use fine particles made of an inorganic compound that have been surface-treated in order to stably exist in the cellulose acylate film. The inorganic fine particles are also preferably used after surface treatment. As the surface treatment method, there are chemical surface treatment using a coupling agent and physical surface treatment such as plasma discharge treatment and corona discharge treatment. In the present invention, it is preferable to use a coupling agent. . As the coupling agent, an organoalkoxy metal compound (for example, a silane coupling agent, a titanium coupling agent, etc.) is preferably used. When inorganic fine particles are used as the fine particles (especially when SiO ₂ is used), treatment with a silane coupling agent is particularly effective. As the silane coupling agent, an organosilane compound represented by the following general formula (11) can be used. Although the usage-amount of the said coupling agent is not specifically limited, Preferably it is recommended to use 0.005-5 mass% with respect to an inorganic fine particle, Furthermore, 0.01-3 mass% is preferable.

(Release agent)
A release agent can be added to the cellulose acylate composition in the present invention. As the release agent, a compound having a fluorine atom is preferable. The compound having a fluorine atom can exhibit an action as a release agent, and may be a low molecular weight compound or a polymer. Examples of the polymer include the polymers described in JP-A No. 2001-269564. A polymer having a fluorine atom is preferably a polymer obtained by polymerizing a monomer containing a fluorinated alkyl group-containing ethylenically unsaturated monomer as an essential component. The fluorinated alkyl group-containing ethylenically unsaturated monomer related to the polymer is not particularly limited as long as it is a compound having an ethylenically unsaturated group and a fluorinated alkyl group in the molecule. A surfactant having a fluorine atom can also be used, and a nonionic surfactant is particularly preferable.

(Optical adjusting agent)
An optical adjusting agent can be added to the cellulose acylate composition in the present invention. Examples of the optical adjusting agent include a retardation adjusting agent, and are described in, for example, JP-A Nos. 2001-166144, 2003-344655, 2003-248117, and 2003-66230. Can be used. By adding an optical adjusting agent, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount of the optical adjusting agent is 0 to 10% by mass, more preferably 0 to 8% by mass, and further preferably 0 to 6% by mass.

(Addition method)
The timing for adding and mixing various additives that can be used in the present invention to the cellulose acylate composition is not particularly limited as long as each additive is added at the time of melt film formation. For example, it may be added at the time of cellulose acylate synthesis, or may be mixed in advance in cellulose acylate before melting, and it is also preferable to form a film while mixing with cellulose acylate during melt film formation. When adding at the time of the synthesis | combination of a cellulose acylate, you may add before and after the precipitation production | generation of a cellulose acylate, and when a cellulose acylate is disperse | distributed in a solution state, you may add. Thereby, a cellulose acylate and an additive can be mixed uniformly.

  In the present invention, a master pellet (cellulose acylate main pellet) in which various additives are contained in cellulose acylate at a higher concentration than desired may be prepared in advance. In that case, it is preferable to prepare cellulose acylate pellets (cellulose acylate sub-pellets) having a low concentration of additives. In that case, the amount of additive in the master pellet is not particularly defined, but is preferably 1.1 to 20 times the final concentration of the additive in the cellulose acylate film, more preferably 2 to 15 times, Preferably it is 2 to 10 times.

The method of adding and mixing various additives that can be used in the present invention to the cellulose acylate composition is not particularly limited, and for example, the following method can be employed.
When the liquid additive or the solid additive is mixed after the cellulose acylate is prepared as a powder, it is important to mix it uniformly. When the additive is a powder, it is effective to use a mixing device in order to uniformly mix the cellulose acylate powder. In addition, when the additive is in liquid form, it is effective to use a mixing device such as a mixer or kneader with stirring, or it can be added directly to the feed of the twin-screw kneader during the pellet manufacturing process using a fixed-volume feed pump. You can also.

  When mixing the cellulose acylate composition with a mixing device, it is desirable to control the humidity, temperature, and oxygen concentration so that the additives and cellulose acylate are stable. At this time, the humidity and temperature are preferably low. The oxygen concentration is preferably low, and the oxygen concentration in the gas is preferably 10% by volume or less, more preferably 5% by volume or less, still more preferably 2% by volume or less, and particularly preferably 1%. The capacity is less than%. The method for reducing the oxygen concentration is not particularly limited, but it can be achieved by degassing with an inert gas (for example, nitrogen, argon, helium, etc.) or vacuum equipment. It is recommended that the additive-containing cellulose acylate composition thus mixed is melt pelletized or film-formed while maintaining a low oxygen concentration. In addition, when it is made by melting in a low oxygen concentration atmosphere in the pelletizing step, it may not be necessary to control the oxygen concentration during melt film formation, and the load on the step is reduced.

<< Method for Producing Cellulose Acylate Film >>
Below, the manufacturing method of the cellulose acylate film of this invention is described in detail. The cellulose acylate film of the present invention is not limited to those produced by these methods.

(1) Pelletization In the present invention, it is preferable that a cellulose acylate composition containing cellulose acylate, a compound, a lactone compound, and other additives is mixed and pelletized prior to melt film formation. It is preferable to dry the cellulose acylate and additives in advance before pelletization. As the moisture content after drying in that case, the cellulose acylate composition is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less. It is.

This can be substituted by using a vent type extruder. Pelletization can be produced by melting the cellulose acylate composition at 180 ° C. to 240 ° C. using a biaxial or uniaxial kneading extruder and then extruding it into noodles and solidifying and cutting in water. . Pelletization may be performed by an underwater cut method in which the material is cut while being extruded directly into water. Preferably, the pellet size is such cross-sectional area is 1 mm ² to 300 mm ^2, a length 1Mm～30mm, and more preferably the cross-sectional area of 2 mm ² 100 mm ^2, length 1.5Mm～10mm. The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 30 rpm to 500 rpm. The extrusion residence time in pelletization is usually 10 seconds to 30 minutes, preferably 10 seconds to 3 minutes. In the pelletization, it is preferable to remove or reduce oxygen. In that case, a preferable oxygen concentration that can be achieved by maintaining an inert gas (for example, nitrogen, helium, argon, etc.) or a reduced pressure state. Is 10% by volume or less, more preferably 5% by volume or less, further preferably 2% by volume or less, and particularly 0.5% by volume or less.

  In addition, although it does not specifically limit about the addition method of each compound to a cellulose acylate composition, as mentioned above, generally mixing at the time of pelletization is recommended and recommended. However, the pellets are melted by adding a high concentration of compounds and other additives to the cellulose acylate master pellets that have been melted and pelletized only in advance, with the melting temperature during pelletization at a low temperature. It is also preferable to put the converted compound addition master pellets into a melt extruder so as to obtain a desired compound addition amount during melt film formation.

(2) Melt film formation Next, melt film formation will be described.

(Dry)
Prior to melt film formation, the moisture in the pellets is dried so that the water content is 0.1% by mass or less, more preferably 0.01% by mass or less. Any commonly used drying method can be used for drying the pellet-shaped resin. For example, a dryer that circulates dehumidified air, a hot air dryer, a vacuum dryer, an ultrasonic dryer, a high-frequency dryer, an infrared dryer, and the like can be used. The drying temperature for this purpose is preferably 40 to 180 ° C, more preferably 60 to 160 ° C, and particularly preferably 80 to 140 ° C. Although the drying efficiency increases as the amount of drying air increases, the amount of air necessary for drying 100 kg of resin per hour is preferably 10 to 200 m ³ / hour, especially considering water removal efficiency and economy. Is 50 to 125 m ³ / hour. The dew point of the drying wind is preferably 0 to −60 ° C., and more preferably −20 to −40 ° C. in consideration of drying efficiency and economy.

(Melt extrusion)
Dry cellulose acylate is fed into the cylinder from the feed port of the extruder.
The screw compression ratio of the extruder is preferably 1.5 to 4.5, more preferably 2.5 to 4.0. L-screw length / D (screw diameter) is preferably 20 to 70, more preferably 24 to 50. The extrusion temperature is preferably 180 to 240 ° C, more preferably 190 to 240 ° C, and particularly preferably 200 to 235 ° C. The barrel of the extruder is preferably heated and melted with a heater divided into 3 to 20.
Any type of screw can be used, such as full flight, mudock, and dalmage. Appropriate screw design can be combined as appropriate in consideration of uniform plasticization, prevention of the occurrence of stagnant parts, and thermal degradation due to shear heating. It is necessary to do. In order to prevent the oxidation of the resin, it is more preferable that the inside of the extruder is carried out in an inert (nitrogen or the like) air stream or while being evacuated using a vented extruder.

(Filtration)
In order to filter foreign matter in cellulose acylate and avoid damage to the gear pump due to foreign matter, it is preferable to perform breaker plate type filtration at the outlet of the extruder. The size of the filter used is preferably 20 to 600 mesh, more preferably 40 to 400 mesh, and particularly preferably 50 to 300 mesh.
For high precision filtration, it is preferable to provide a leaf type disk filter type filtration device after passing through the gear pump. Filtration may be performed in a single stage or in multiple stages. The filtration accuracy of the filter medium is preferably 3 to 15 μm, more preferably 3 to 10 μm, and particularly preferably 3 to 5 μm. The filter medium is preferably stainless steel or steel, and stainless steel is particularly preferable. The filter medium can be a knitted wire or a sintered metal filter medium, and the latter is particularly preferable.

(Gear pump)
It is preferable to install a gear pump between the extruder and the die in order to improve the thickness accuracy (reduction in fluctuation of the discharge amount). Thereby, the resin pressure fluctuation width of the die portion can be within ± 1%.
In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw is also preferable. A high-precision gear pump using three or more gears is also effective. Since the staying part in the gear pump causes resin deterioration, a structure with less staying is preferable. It is also effective to prevent the heat-degraded polymer from being mixed by discharging the resin that has accumulated in the bearing portion and is thermally deteriorated from the clearance of the shaft.
In order to stabilize the extrusion pressure, it is preferable to reduce the temperature fluctuation of the adapter connecting the extruder and the gear pump, and the gear pump and the die. For this purpose, it is more preferable to use an aluminum cast heater.

(Die)
Any type of commonly used T-die, fishtail die, and hanger coat die may be used as long as the molten resin stays in the die. Also, there is no problem to insert a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance of the T-die outlet portion is generally 1.0 to 20.0 times the film thickness, and more preferably 3.0 to 15 times. Especially preferably, it is 5.0 to 10 times.
The die clearance is preferably adjustable at intervals of 40 to 50 mm, more preferably at most 25 mm. A method of measuring the downstream film thickness and feeding it back to the die thickness adjustment is also effective in reducing the thickness variation. Since the functional layer is provided on the outer layer, it is possible to produce a film having two or more kinds of structures using a multilayer film forming apparatus. The preferred residence time of the resin from entering the extruder through the supply port to exiting the die is 2 to 60 minutes, more preferably 2.5 to 30 minutes, and even more preferably 2.5 to 20 minutes. .

(cast)
The molten resin extruded from the die onto the sheet is cooled and solidified on a casting drum to obtain a film. At this time, it is preferable to increase adhesion by using a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method. Edge pinning (a method in which only both end portions of the film are in close contact) is also preferable.
A casting drum is preferably used by using 1 to 8 casting drums, more preferably 2 to 5 casting drums. The roll diameter is preferably 50 to 5000 mm, more preferably 150 to 1000 mm. The interval between the plurality of rolls is preferably 0.3 to 300 mm, more preferably 3 to 30 mm between the surfaces. The casting drum is preferably 60 ° C to 160 ° C, more preferably 80 ° C to 140 ° C.
Then, it peels off from a casting drum, winds up after passing through a nip roll. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 50 μm to 200 μm.

The cellulose acylate film of the present invention preferably uses a so-called touch roll method in which a pellet is extruded from a die and then formed by a touch roll. After extruding the pellet from the die, the pressure is 0.1 to 10 MPa by a touch roll. More preferably, the film is formed by pressing. When the so-called touch roll method is used, the surface of the touch roll may be a resin such as rubber or Teflon, or a metal roll. Further, it is possible to use a roll called a flexible roll because the roll surface is slightly dented by the pressure when touched by reducing the thickness of the metal roll, and the crimping area is widened. This thickness is preferably 0.1 mm to 7 mm, more preferably 0.2 mm to 5.5 mm, and still more preferably 0.2 mm to 4 mm. The touch roll temperature is preferably 60 ° C to 160 ° C, more preferably 80 ° C to 140 ° C. As described above, the pressure of the touch roll is preferably 0.1 to 10 MPa, more preferably 0.2 to 8 MPa, and still more preferably 0.3 to 5 MPa. “Pressing” as used herein refers to a value (F / A) obtained by dividing the force (F: unit N) for pressing the touch roll against the casting roll by the contact area (A: unit m ² ) between the touch roll and the casting roll. : Unit Pa). For example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, International Publication WO97 / 28950, JP-A-2004-216717, and the like. The thing of Unexamined-Japanese-Patent No. 2003-145609 can be utilized.

(Winding)
It is preferable to trim both ends of the film before winding. The trimmed portion may be reused as a film raw material. As the trimming cutter, any rotary cutter, shear blade, knife, or the like may be used. Regarding the material, carbon steel, stainless steel, and ceramic can be used.
A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 3 kg / m width to 20 kg / width. The take-up tension may be taken up with a constant take-up tension, but it is more preferable that the take-up tension be taper according to the take-up diameter.
It is also necessary to adjust the draw ratio between the nip rolls so that the film does not receive a tension higher than the specified tension in the middle of the line.
Prior to winding, a laminated film may be attached to at least one side.

(Recovery)
A waste film is generated during the trimming step for adjusting the formed unstretched film or stretched film to the product size, or when the film forming conditions are adjusted. Since the amount of generation reaches about 5 to 30% of the input raw material, it is extremely important from the viewpoint of cost and environment to grind the waste film and mix it with a new raw material or to reuse it alone. The pulverized and dried film may be supplied to the raw material tank through an air feed pipe, mixed with the virgin raw material, and supplied to the hopper. Further, the pulverized film and the virgin raw material may be separately weighed and supplied to the extruder. The mixing ratio of the pulverized film raw material and the virgin raw material is preferably 1:99 to 70:30, more preferably 5:95 to 50:50, by weight. Thereby, even if the bulk density of a pulverized film and a virgin raw material differs, the supply stability to an extruder is favorable and preferable. However, when re-pelletizing, if there is no problem in film physical properties, it is not necessary to be in the above range, and it is possible to mix at an arbitrary blending ratio.

  FIG. 1 shows a schematic view of an apparatus for carrying out melt film formation that can be preferably employed in the present invention. FIG. 1 is a schematic view showing an example of an apparatus for carrying out melt film formation using cellulose acylate pellets in the present invention. In FIG. 1, 101 is a kneading extruder, 102 is a gear pump, 103 is a filtration unit, 104 is a die, 105 is a touch roll, 106 is a casting cooling drum, 107 is cellulose acylate, 108 is a longitudinal stretching process unit, and 109 is a lateral direction. The drawing process unit 110 indicates a winding process unit. The stretching will be described later. When forming an unstretched film, after passing through the casting cooling drum 106, it can be wound without passing through the longitudinal stretching step 108 and the lateral stretching step 109.

<Characteristics of unstretched cellulose acylate film>
(optical properties)
Next, preferable optical properties of the cellulose acylate film of the present invention will be described.
In this specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). A detailed measurement method will be described later.

  The front retardation (Re) of the cellulose acylate film of the present invention is preferably 0 to 300 nm, and the absolute value of retardation (Rth) in the thickness direction is preferably 0 to 700 nm. Furthermore, it is more preferable that Re is 0 to 250 nm and the absolute value of Rth is 0 to 400 nm, particularly, Re is 0 to 200 nm, and the absolute value of Rth is preferably 0 to 350 nm. In particular, the cellulose acylate film of the present invention is effective for use as a polarizing plate protective film. In this case, Re is 0 to 20 nm, Rth is preferably 0 to 60 nm, and Re is 0 to 10 nm. Rth is preferably 0 to 40 nm, Re is preferably 0 to 5 nm, and Rth is particularly preferably 0 to 20 nm.

  The cellulose acylate film of the present invention can improve the problem of fluctuation of optical characteristics accompanying humidity change, and the difference between the optical characteristics of 10% relative humidity and 25% optical characteristics at 25 ° C. is small. Is one of the features. Optical characteristic variation due to humidity change can be evaluated by the absolute value of the change amount due to humidity change between Re and Rth. That is, the Re humidity change (nm) is the absolute value of the difference between Re (relative humidity 80%) and Re (relative humidity 10%), and the Rth humidity change (nm) is Rth (relative humidity 80%). ) And Rth (relative humidity 10%). The cellulose acylate film of the present invention preferably has a Re humidity change of 10 nm or less, more preferably 5 nm or less, and further 1 nm or less. Also, the Rth humidity change is preferably 25 nm or less, more preferably 20 nm or less, and further 15 nm or less. Compared with the conventional cellulose triacetate film, the cellulose acylate film of the present invention has a humidity change of 2/3 to 1/2.

The cellulose acylate film of the present invention can also control the behavior of optical properties with respect to wavelength. That is, the absolute value of the difference between Re (400) and Re (700) at wavelengths of 400 nm and 700 nm is preferably 0 to 15 nm, and the absolute value of the difference between Rth (400) and Rth (700) is 0 to It is preferably 35 nm. When this is expressed by a formula, the cellulose acylate film of the present invention preferably satisfies the following formulas (A-1) and (A-2).
Formula (A-1) 0 ≦ | Re (700) −Re (400) | ≦ 15 nm
Formula (A-2) 0 ≦ | Rth (700) −Rth (400) | ≦ 35 nm
(In the formula, Re (400) and Re (700) represent front retardation (Re) at wavelengths of 400 nm and 700 nm, and Rth (400) and Rth (700) represent letters in the thickness direction at wavelengths of 400 nm and 700 nm. Represents the foundation (Rth).)

  The cellulose acylate film of the present invention can suppress Re unevenness and Rth unevenness. Re unevenness and Rth unevenness here are sampled 7 points every 20cm from the end in the width direction in each region of 10m, 250m and 450m in the length direction of the cellulose acylate film, preparing a total of 21 samples These samples were conditioned at 25 ° C. and 60% relative humidity for 3 hours, measured for Re and Rth under the same environment, and calculated by calculating the difference between the maximum and minimum values. It is done. In the cellulose acylate film of the present invention, Re unevenness and Rth unevenness are each preferably less than 3.0 nm, more preferably less than 1.0 nm, more preferably 0.8 nm or less, and More preferably, it is 6 nm or less. If the above 21 samples cannot be collected, Re unevenness and Rth unevenness are calculated by a method according to this.

  In the cellulose acylate film of the present invention, the intrinsic birefringence in the in-plane direction at a wavelength of 590 nm in an environment of 25 ° C. and a relative humidity of 60% is preferably 0 to 0.001, and the intrinsic birefringence in the thickness direction. The absolute value of is preferably 0 to 0.003. More preferably, the intrinsic birefringence in the in-plane direction is 0 to 0.0008, and the absolute value of the intrinsic birefringence in the thickness direction is 0 to 0.0025. More preferably, the intrinsic birefringence in the in-plane direction is 0 to 0.0006, and the absolute value of the intrinsic birefringence in the thickness direction is 0 to 0.001.

(Axis misalignment)
In the cellulose acylate film of the present invention, the optical slow axis is preferably parallel or perpendicular to the casting direction or the width direction. In particular, when a stretching process is performed, it is preferable that the stretching is closer to 0 ° when stretching in the casting direction. Specifically, 0 ± 3 ° is more preferable, 0 ± 1.5 ° is more preferable, and 0 ± 0.5 ° is particularly preferable. When stretched in the width direction, 90 ± 3 ° or −90 ± 3 ° is preferable, more preferably 90 ± 1.5 ° or −90 ± 1.5 °, and still more preferably 90 ± 0.5 ° or − 90 ± 0.5 °.

(Elastic modulus, breakage progress, thermal dimensional change, water permeability, equilibrium water content)
Elastic modulus of the cellulose acylate film of the present invention is preferably from ^{1.5kN / mm 2 ~3.5kN / mm 2} , more preferably from ^{1.8kN / mm 2 ~2.6kN / mm 2} . The breaking elongation is preferably 3% to 300%. Tg is preferably 95 ° C to 145 ° C. The thermal dimensional change at 80 ° C. for one day is preferably 0% to ± 1% in both the vertical and horizontal directions, and more preferably 0% to ± 0.3%. The water permeability at 40 ° C. / RH 90% 300g / m ² · day to 1000 g / m ² · day is preferred, more preferably 500 g / m ² · day ~800g / m ² · day. The equilibrium moisture content at 25 ° C./80% relative humidity is preferably 1% by mass to 4% by mass, and more preferably 1.5% by mass to 2.5% by mass.

(Residual solvent amount)
The cellulose acylate film of the present invention contains no or very little residual solvent. The amount of residual solvent is preferably 0.01% by mass or less, and most preferably zero. In particular, in the production method of the present invention by melt film formation, a solvent is not used at the time of film formation.

(Thickness and unevenness)
The film thickness of the cellulose acylate film of the present invention is preferably 20 to 300 μm, more preferably 30 μm to 200 μm, still more preferably 30 μm to 150 μm, and particularly preferably 40 to 120 μm. Therefore, the film thickness of the unstretched film on the premise that the film is stretched is preferably set to a thick original film extruded film thickness in advance according to the stretch ratio. The thickness variation of the cellulose acylate film of the present invention is preferably 0 to 5 μm in both the thickness direction and the width direction, more preferably 0 to 3 μm, and still more preferably 0 to 2 μm. The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably as close to 0 °, + 90 °, or −90 °.

(Kishimi value)
In the present invention, by adding fine particles or a slipping agent to the cellulose acylate film, the kimi value can be reduced and the transportability can be improved. In the present invention, the dynamic and static kimi values of the cellulose acylate film are both preferably 0.2 to 1.5, more preferably 0.2 to 1.3, and still more preferably 0.00. 256-1.0. When the presence state of the fine particles is coarse, the kishimi value may be small or large, and not only the transportability is unfavorable but also not recommended with the occurrence of scratches. A method for measuring the kishimi value will be described later.

(Arithmetic mean roughness)
The cellulose acylate film containing fine particles has a surface roughness within an appropriate range. The degree of the surface roughness is represented by a commonly used arithmetic average roughness (Ra). The arithmetic average roughness (Ra) of the cellulose acylate film of the present invention is preferably 1 nm to 500 nm, more preferably 1 nm to 250 nm, and particularly preferably 1 nm to 200 nm. The arithmetic average roughness (Ra) can be measured by a generally used contact type or non-contact type surface roughness measuring machine.

(Transmittance)
The transmittance of the cellulose acylate film of the present invention is preferably 90% or more, more preferably 91% or more, and particularly preferably 92% or more. The transmittance is obtained by cutting a film sample into 20 mm × 70 mm, and measuring the transmittance of visible light (615 nm) with a transparency measuring instrument (AKA photoelectric colorimeter, manufactured by KOTAKI Corporation) at 25 ° C. and 60% relative humidity. Is obtained.

(Haze)
The cellulose acylate film of the present invention preferably has a haze in the range of 0 to 1.5%, more preferably 0 to 1.2%, still more preferably 0 to 0.8%, particularly Preferably it is 0.01 to 0.5%. The haze is measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and a relative humidity of 60% after cutting a film sample into 40 mm × 80 mm.

<Physical properties of stretched and stretched cellulose acylate film>
(Stretching)
In the present invention, in order to control film characteristics, it is also preferable to perform a stretching process to stretch the film. For example, an unstretched film can be stretched to control Re and Rth. At this time, the stretching temperature is preferably (Tg to Tg + 50 ° C.), more preferably (Tg + 5 ° C.) to (Tg + 20 ° C.). A preferred stretching ratio is 1% to 300%, more preferably 3% to 200%, at least one. It is more preferable to stretch one stretch ratio larger than the other, and the smaller stretch ratio is preferably 1% to 30%, more preferably 3% to 20%, and the larger stretch ratio is 30% to 30%. 300% is preferable, and more preferably 40% to 150%. These stretching operations may be performed in one stage or in multiple stages. The draw ratio here is determined using the following equation.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
Such stretching can be carried out using a nip roll, a tenter or the like. Moreover, you may use the simultaneous biaxial stretching method as described in Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.

Re and Rth of the stretched cellulose acylate film preferably satisfy the following formula.
Rth ≧ Re
200 ≧ Re ≧ 0
500 ≧ Rth ≧ 30
In addition, Re and Rth of the stretched cellulose acylate film more preferably satisfy the following formula.
Rth ≧ Re × 1.2
100 ≧ Re ≧ 20
350 ≧ Rth ≧ 80

  In addition, the angle θ formed by the film forming direction (longitudinal direction) and the slow axis is preferably 0 ± 3 °, more preferably 0 ± 1 ° in the case of longitudinal stretching. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, and 90 ± 1 ° or −90 ± 1 ° is more preferable. The thickness of the cellulose acylate film after stretching is preferably 15 μm to 200 μm, more preferably 40 μm to 140 μm. The thickness unevenness is preferably 0% to 3% in both the longitudinal direction and the width direction, and more preferably 0% to 1%.

(Physical properties)
The physical properties of the stretched cellulose acylate film are preferably in the following ranges.
The tensile modulus is preferably 1.5 kN / mm ² or more and less than 3.0 kN / mm ² , more preferably 1.8 kN / mm ^{2 to} 2.6 kN / mm ² .
The breaking elongation is preferably 3% to 100%, more preferably 8% to 50%.
Tg is preferably 95 ° C to 145 ° C, more preferably 105 ° C to 135 ° C.
The thermal dimensional change after standing at 80 ° C. for 1 day is preferably 0% to ± 1% in both the vertical and horizontal directions, and more preferably 0% to ± 0.3%.
40 ° C., water permeability at 90% relative humidity, preferably 300 g / m ² · day to 1000 g / m ² · day, more preferably from 500 g / m ² · day ~800g / m ² · day.
The equilibrium water content at 25 ° C. and 80% relative humidity is preferably 1% by mass to 4% by mass, and more preferably 1.5% by mass to 2.5% by mass.
The haze is preferably 0% to 3%, more preferably 0% to 1% or less. The total light transmittance is preferably 90% to 100%.

(Surface shape)
In the cellulose acylate film of the present invention, the depth of the die line formed in the longitudinal direction is 500 nm or less, the width is 0.2 mm or more, more preferably, the depth is 100 nm or less, the width is 0.3 mm or more, and more preferably, The depth is 50 nm or less and the width is 0.5 mm or more. For the height and depth of the die line, the unevenness of the film was measured using a three-dimensional structural analysis microscope (New View Model 6000 manufactured by Zygo).
The number of the die lines is 5/10 cm or less, more preferably 3/10 cm or less, and further preferably 1/10 cm or less with respect to the width direction. The number of die lines was set such that the film (full width of film formation × longitudinal direction 30 cm) was placed in parallel with an interval of 10 mm in front of a white screen, and 1 m away from the center of this film in a direction of 32.5 degrees. Projected from a slide projector (for example, Color Cabin III manufactured by Cabin Kogyo Co., Ltd.), the number of stripes (light brightness) parallel to the film-forming direction (MD) projected on the screen is 3 mm or less in width. And the number per 10 cm width was determined.
Further, the foreign matter having a maximum diameter of 50 μm or more contained in the cellulose acylate film of the present invention is 0/3 m length × full width, and the foreign matter having a maximum diameter of 20-50 μm or less is 30/3 m length × full width or less. . In addition, when the film is placed between two polarizing plates arranged in a crossed Nicol state, when observing from the side of the other polarizing plate by applying light from one polarizing plate, a foreign matter having a maximum diameter of 20 to 50 μm Among them, the number of bright spots is 15/3 m long × full width or less, more preferably 10/3 m long × full width or less, and further preferably 5 / cm ² or less. In addition, the measurement of the number and magnitude | size of a foreign material can sample a film-forming film by 3m length x full width, and can measure the number and magnitude | size using an optical microscope.
When the number of foreign substances contained in the die line and film is within the above range, even when incorporated in a liquid crystal display unit having a high-brightness backlight unit, a good display state can be obtained without light leakage.

《Functionalization of cellulose acylate film》
Next, the preferable aspect in the case of providing a function further to the cellulose acylate film of this invention is described.

(surface treatment)
The cellulose acylate film can achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer) by optionally performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The “glow discharge treatment” here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas.
The glow discharge treatment includes a low temperature plasma treatment that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, chlorofluorocarbons such as tetrafluoromethane, and mixtures thereof. Is mentioned. Details of these are described in detail in pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  Next, the alkali saponification treatment preferably used as the surface treatment of the cellulose acylate film of the present invention will be specifically described. The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the immersion method, it passes for 0.1 minutes to 10 minutes through a bath in which an aqueous solution of hydroxide ions such as NaOH and KOH having a concentration of 0.3 mol / L to 4.0 mol / L is heated to 20 ° C to 90 ° C. This can be achieved by neutralization, washing with water and drying.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specifically, these saponification methods are described in, for example, JP-A No. 2002-82226 and WO 02/46809 pamphlet.

  The surface energy of the solid obtained by these methods should be determined by the contact angle method, the wet heat method, and the adsorption method as described in “Basics and Applications of Wetting” (Realize, 1989.12.10). It is preferable to use the contact angle method. The contact angle (25 ° C./60% relative humidity) of water on the cellulose acylate film surface of the present invention is preferably 45 ° or less, more preferably 10 to 45 °, and particularly preferably 10 to 40 °. Preferably, 10 to 30 ° is most preferable.

  As a method of adhering the functional layer to the cellulose acylate film of the present invention, after surface activation treatment, a method of directly applying the functional layer on the cellulose acylate film to obtain adhesive force, and once performing some surface treatment There is a method in which an undercoat layer (adhesive layer) is provided or a functional layer is applied thereon after or without surface treatment. Various ingenuity has also been made for the constitution of the undercoat layer. For example, it is well adhered to a support (cellulose acylate film) as a single layer method in which one undercoat layer is composed of one layer or as a first layer. There is a so-called multi-layer method in which a layer (first undercoat layer) is provided, and a second undercoat layer that adheres well to the functional layer as a second layer is applied thereon. This layer may be applied after the above surface treatment or may be applied without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Institute of Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<< Use of Cellulose Acylate Film of the Present Invention >>
The cellulose acylate film of the present invention has a functional layer described in detail on pages 32 to 45 of the Japan Institute of Invention Disclosure Technical Report (public technical number 2001-1745, published on March 15, 2001, Japan Society of Invention). It is preferable to form various optical films in combination. Among these, application of a polarizing film (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

(1) Production of Polarizing Plate The polarizing plate of the present invention is constituted by laminating at least one layer of the cellulose acylate film of the present invention on a polarizer.

(Polarizer)
The polarizer in the present invention is preferably composed of polyvinyl alcohol (PVA) and a dichroic molecule. Further, as described in JP-A-11-248937, a polyvinylene-based polarizer in which a polyene structure is generated by dehydrating and dechlorinating PVA and polyvinyl chloride and oriented can be used. . A coating type polarizer represented by Optiva Inc. can also be used.

  The PVA is a polymer material obtained by saponifying polyvinyl acetate, and may contain a component copolymerizable with vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, and vinyl ethers. Absent. In addition, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like can also be used.

  The saponification degree of the PVA is not particularly limited, but is preferably 80 to 100 mol%, particularly preferably 90 to 100 mol% from the viewpoint of solubility and the like. The degree of polymerization of PVA is not particularly limited, but is preferably 1000 to 10,000, and particularly preferably 1500 to 5000. The syndiotacticity of PVA is preferably 55% or more for improving durability as described in Japanese Patent No. 2978219, but 45 to 52.5% described in Japanese Patent No. 3317494 is also preferably used. be able to.

  After forming the PVA into a film, a dichroic molecule is introduced, dyed and stretched to obtain a polarizer. Detailed polarizer manufacturing methods are disclosed in paragraphs [0075] to [0082] of JP-A-2005-138375, paragraphs [0138] to [0141] of JP-A-2006-2026, and JP-A-2006-45500. Those described in the paragraph numbers [0099] to [0108] of FIG.

(Polarizer)
In the polarizing plate of the present invention, the adhesion treatment between the polarizer and the cellulose acylate film (protective film) is not particularly limited. For example, an adhesive made of a vinyl alcohol polymer, boric acid, It can be carried out through an adhesive comprising at least a water-soluble crosslinking agent of vinyl alcohol polymer such as borax, glutaraldehyde, melamine and oxalic acid. In particular, it is preferable to use a polyvinyl alcohol-based adhesive because it has the best adhesion to the polyvinyl alcohol-based film. Such an adhesive layer can be formed as a coating / drying layer of an aqueous solution, but other additives and a catalyst such as an acid can be blended as necessary when preparing the aqueous solution. Detailed manufacturing methods of polarizing plates and polarizing plate characteristics are disclosed in paragraphs [0008] to [0020] of JP-A-2005-128520, paragraphs [0007] to [0013] of JP-A-2005-266222, and JP-A-2005-266222. Paragraph Nos. [0083] to [0113] of JP-A-2005-138375, paragraph numbers [0142] to [0145] of JP-A 2006-2026, and paragraph numbers [0109] to [0111] of JP-A 2006-45500. Those can be preferably used.

  In general, in a liquid crystal display device, a liquid crystal cell is provided between two polarizing plates, and the liquid crystal cell is generally injected between two substrates. Therefore, a normal liquid crystal display device has four polarizing plate protective films. The cellulose acylate film of the present invention may be used for any of the four polarizing plate protective films. The polarizing plate protective film is a polarizing plate formed by laminating a first protective film, a polarizer, and a second protective film. When the two polarizing plates are orthogonal, the second protective film is disposed on the inner side (liquid crystal cell side). . In order to further improve the viewing angle dependency of liquid crystal display devices, change with time, light leakage and color change during black display, the cellulose acylate film of the present invention is provided with a polarizer and a liquid crystal layer (liquid crystal cell) in the liquid crystal display device. ) Can be used particularly advantageously as the second protective film.

  Further, the first protective film of the upper polarizing plate disposed on the upper surface (viewing side) of the liquid crystal cell is selected from the melt-formed cellulose acylate film of the present invention, or the triacetyl cellulose film formed by solution casting, It is preferable to provide at least one layer of a hard coat layer, an antiglare layer, and an antireflection layer on the surface and arrange it on the viewer side as the first protective film of the polarizing plate. The first protective film of the lower polarizing plate arranged on the lower surface (back side) of the liquid crystal cell is selected from the melt-formed cellulose acylate film of the present invention or the triacetyl cellulose film formed by solution casting. The first protective film is preferably disposed on the backlight unit side.

(2) Production of optical compensation film The optical compensation film of the present invention uses, for example, the cellulose acylate film of the present invention as a substrate, and has an optically anisotropic layer on the substrate.
The optically anisotropic layer is for compensating for a liquid crystal compound in a liquid crystal cell in black display of a liquid crystal display device, and an alignment film is formed on the cellulose acylate film, It is formed by giving.

(Alignment film)
An alignment film is provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer. Detailed methods and materials for forming an alignment film are disclosed in paragraphs [0148] to [0159] of JP-A-2006-2026, paragraphs [0114] to [0127] of JP-A-2006-45500, and JP-A-2006. Those described in paragraph numbers [0080] to [0085] of Japanese Patent No. 45501 can be preferably used. The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

  Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

  The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(Rod-like liquid crystalline molecules)
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.

  For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystal molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable group described in paragraphs [0064] to [0086] of JP-A-2002-62427 is described. And polymerizable liquid crystal compounds.

(Discotic liquid crystalline molecules)
For discotic liquid crystal molecules, C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. The discotic core and the polymerizable group are preferably compounds that are bonded via a linking group, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] in JP-A 2000-155216.

  In hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the plane of the polarizing plate increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the plane of the polarizing plate. is doing. It is preferable that the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing plate decreases as the distance increases. Furthermore, as a change in the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing plate, a change including continuous increase, continuous decrease, intermittent increase, intermittent decrease, continuous increase and continuous decrease, Alternatively, intermittent changes including increases and decreases are possible. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing plate includes a region where the angle does not change, it may be increased or decreased as a whole. Furthermore, it is preferable that the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing plate changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing plate side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can be adjusted by selecting liquid crystal molecules and additives as described above.

(Other composition of optically anisotropic layer)
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.

A cellulose ester can be mentioned as an example of the polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Formation of optically anisotropic layer)
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.

  As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Aciloin compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,212,970).

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. A protector may be provided on the optically anisotropic layer.

  It is also preferable to combine this optical compensation film and a polarizing plate. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing plate. As a result, without using a polymer film between the polarizing plate and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) accompanying the change in the size of the polarizing plate is produced. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

  The inclination angle between the polarizing plate and the optical compensation layer is stretched so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the liquid crystal cell in the vertical or horizontal direction. It is preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the LCD.

(3) Antireflection film The cellulose acylate film of the present invention can be preferably applied to a hard coat layer, an antiglare layer and an antireflection layer. In the antireflection film of the present invention, for example, the cellulose acylate film of the present invention is used as a substrate. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., any or all of a hard coat layer, an antiglare layer and an antireflection layer are provided on one or both sides of the cellulose acylate film of the present invention. Can be granted. Desirable embodiments as such a hard coat layer, an antiglare layer, and an antireflection layer are disclosed in the Journal of the Invention Association (Technical No. 2001-1745, published on March 15, 2001, Invention Association), pages 54-57. Page, paragraph numbers [0137] to [0167] in JP-A-2005-178194, paragraph numbers [0136] to [0154] in JP-A-2005-325258, and paragraph number [0153] in JP-A-2006-45500. ] To [0175] and paragraph numbers [0095] to [0103] of JP-A-2006-45501. These manufacturing methods can be preferably used.

<Liquid crystal display device>
The cellulose acylate film of the present invention, and the polarizing plate, optical compensation film and antireflection film of the present invention using the cellulose acylate film of the present invention can be used in liquid crystal display devices of various display modes. Each liquid crystal mode in which these films are used will be described below. Among these modes, the cellulose acylate film, polarizing plate and optical compensation film of the present invention are particularly preferably used for TN, STN, VA and IPS mode liquid crystal display devices. These liquid crystal display devices may be any of a transmissive type, a reflective type, and a transflective type.

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate. The cellulose acylate film of the present invention may be used as a support for a retardation plate of a TN type liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. As for the optical compensation sheet used in the TN type liquid crystal display device, each of JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572, and Mori. Other papers (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068) are described.

(STN type liquid crystal display device)
The cellulose acylate film of the present invention may be used as a support for a retardation plate of an STN type liquid crystal display device having an STN mode liquid crystal cell. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 °, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation sheet used in the STN type liquid crystal display device is described in JP-A-2000-105316.

(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .

(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers 28 (1997) 845), (3) Rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied, and twisted A liquid crystal cell in a domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (LCD interface) Announced at National 98).
The cellulose acylate film of the present invention may be used as an optical compensator or a support for an optical compensator in a VA liquid crystal display device having a VA mode liquid crystal cell. Or it is used especially advantageously as a protective film of a polarizing plate. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS mode liquid crystal display)
The feature is that the rod-like liquid crystalline molecules are aligned substantially horizontally in the plane when no voltage is applied, and this is characterized by switching by changing the orientation direction of the liquid crystal with or without voltage application. Specifically, JP 2004-365951 A, JP 2004-12731 A, JP 2004-215620 A, JP 2002-221726 A, JP 2002-55341 A, JP 2003-195333 A. Those described in the publication can be used.
The cellulose acylate film of the present invention may be used as an optical compensator or a support for an optical compensator in a VA liquid crystal display device having a VA mode liquid crystal cell. Or it is used especially advantageously as a protective film of a polarizing plate. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the cellulose acylate film of the present invention contributes to widening the viewing angle and improving the contrast.

(Reflective liquid crystal display)
The cellulose acylate film of the present invention is also advantageously used as a retardation plate of a TN type, STN type, HAN type, GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN type reflective liquid crystal display device is described in JP-A-10-123478, WO98 / 48320 pamphlet, and Japanese Patent No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device is described in International Publication No. 00/65384 pamphlet.

(Other liquid crystal display devices)
The transparent polymer film of the present invention is also advantageously used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell of ASM (Axially Symmetric Aligned Microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).

<< Measurement method and evaluation method >>
Below, it describes about the measuring method and evaluation method of a cellulose acylate and a cellulose acylate film. The measurement values described in the present application are measured by the method described below.

(Degree of substitution of cellulose acylate)
Substitution degree of the acyl group, a method a method analogous ASTM D-817-91, and complete hydrolysis of cellulose acylate to quantify the free carboxylic acid or a salt thereof by gas chromatography or high performance liquid chromatography, ¹ It was determined by using a method by H-NMR or ¹³ C-NMR alone or in combination.

(Molecular weight of cellulose acylate)
Cellulose acylate resin was dissolved in THF to prepare a 0.5 mass% sample solution. This was measured using GPC under the following conditions to determine the weight average molecular weight (Mw) and the number average molecular weight (Mn). The calibration curve was prepared using polystyrene (TSK standard polystyrene: molecular weight 1050, 5970, 18100, 37900, 190000, 706000). The values obtained by dividing Mw and Mn by the molecular weight per segment determined from the degree of substitution determined by the above method were defined as DPw and DPn, respectively.
Column: TSK GEL Super HZ4000, TSK GEL Super HZ2000,
TSK GEL Super HZM-M, TSK Guard Column Super HZ-L,
Column temperature: 40 ° C
Eluent: THF
Flow rate: 1 ml / min Detector: RI

(Residual sulfuric acid amount)
The sulfate group content of cellulose acylate was measured by ASTM D-817-96, oxidative decomposition / coulometric titration method, etc., and the amount was defined by the sulfur atom content.

(Residual metal amount)
After the cellulose acylate was incinerated, it was quantified by ICP-MS analysis.

(Measurement of Tg)
20 mg of a sample was placed in a DSC measurement pan. This was heated to 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature was raised again to 30 ° C. to 250 ° C., and the temperature at which the baseline began to deviate from the low temperature side was defined as Tg.

(Measurement of Re and Rth)
In the present specification, Re and Rth respectively represent in-plane retardation and retardation in the thickness direction at a wavelength of 590 nm. Re is measured in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments) by making light with a wavelength of 590 nm incident in the normal direction of the film unless otherwise specified.
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth is calculated by the following method.
Rth is defined as Re, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any direction in the film plane is the rotation axis). )) From the normal direction to -50 ° to + 50 ° with respect to the normal direction of the film, and incident light of wavelength 590 nm from each inclined direction in steps of 10 °, measuring a total of 11 points. KOBRA 21ADH or WR calculates based on the retardation value, the average refractive index, and the input film thickness value.
In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. After changing its sign to negative, KOBRA 21ADH or WR calculates.
In addition, the retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotary axis) (in the case where there is no slow axis, the arbitrary direction in the film plane is the rotary axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (b) and (c).

［式中、Ｒｅ（θ）は法線方向から角度θ傾斜した方向におけるレタ−デーション値をあらわす。また、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘおよびｎｙに直交する方向の屈折率を表す。］
式（ｃ）： Ｒｔｈ＝(（ｎｘ＋ｎｙ）／２−ｎｚ)×ｄ

[In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. ]
Formula (c): Rth = ((nx + ny) / 2−nz) × d

When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth is calculated by the following method.
Rth is the Re in 10 degree steps from −50 degrees to +50 degrees with respect to the normal direction of the film, with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis). Eleven light points with a wavelength of 590 nm are incident from the inclined direction, and KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value.
By inputting these average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

(Re and Rth fluctuations with humidity)
The cellulose acylate film was measured in the same manner as described above at 25 ° C. and 10% relative humidity, and Re (relative humidity 10%) and Rth (relative humidity 10%) were determined. Further, these samples were similarly measured at 25 ° C. and a relative humidity of 80%, and Re (relative humidity 80%) and Rth (relative humidity 80%) were obtained. For each sample, humidity Re fluctuation and humidity Rth fluctuation were determined according to the following formula.
Humidity Re variation (% / relative humidity%) = [100 × {absolute value of difference between Re (relative humidity 80%) and Re (relative humidity 10%)} / Re (relative humidity 60%)] / 70
Humidity Rth fluctuation (% / relative humidity%) = [100 × {absolute value of difference between Rth (relative humidity 80%) and Rth (relative humidity 10%)} / Rth (relative humidity 60%)] / 70

(Re unevenness, Rth unevenness)
In each region of 10 m, 250 m, and 450 m in the length direction of the cellulose acylate film, 7 samples were sampled at intervals of 20 cm from the end in the width direction, and a total of 21 samples were prepared. These samples were conditioned at 25 ° C. and 60% relative humidity for 3 hours, and Re and Rth were measured in the same environment. The difference between the maximum and minimum values obtained was defined as Re unevenness and Rth unevenness, respectively. evaluated. The smaller the value, the smaller the optical characteristic variation and the better.

(Axis misalignment)
The cellulose acylate film was cut out to 70 mm × 100 mm, and the axis deviation angle was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). 20 points were measured at equal intervals over the entire width in the width direction of the cellulose acylate film, and the average value of absolute values was obtained. The range of the slow axis angle (axis deviation) is the measurement of 20 points at equal intervals over the entire width direction, and the difference between the average of the absolute value of the axis deviation and the average of the four points from the smaller absolute value. Is taken.

(Daisy)
Evaluation of the die streak generated in a streak shape in the casting direction (length direction) of the cellulose acylate film was performed by visual observation under a reflected light source. The evaluation criteria were as follows.
A: Dice lines were not seen.
B: Dice lines were slightly seen.
C: There was a noticeable die streak.
D: Dice lines were remarkably generated on the entire surface.

(Surface shape)
The cellulose acylate film was cut out to a total width of 30 cm in the flow direction, and the number of foreign matters and die lines was set at 32.5 degrees from the center of the film by placing the film in parallel at a distance of 10 mm in front of a white screen. 3 mm out of the stripes (light brightness) parallel to the film forming direction (MD) projected from the slide projector (for example, Color Cabin III manufactured by Cabin Kogyo Co., Ltd.) installed 1 m away in the direction. The number of the width or less was counted over the entire width, and the number per 10 cm width was obtained. The evaluation criteria were as follows.
A: Soybean was 0/10 cm or less.
B: Soybean was 2/10 cm or less.
C: Soybean was 5/10 cm or less.
D: More than 5 soybeans / 10 cm.

(Foreign matter)
After the cellulose acylate film is sampled with a total width of 3 m in the flow direction and foreign matter in the film is visually detected under a reflection light source, the number and size thereof can be measured using an optical microscope. The evaluation criteria were as follows.
A: The number of luminescent spots among foreign substances having a maximum diameter of 20 to 50 μm was 5/3 m length × full width or less.
B: The number of bright spots among foreign substances having a maximum diameter of 20 to 50 μm was 15 pieces / 3 m length × full width or less.
C: The number of bright spots among foreign substances having a maximum diameter of 20 to 50 μm was 30/3 m length × full width or less.
D: The number of bright spots among foreign substances having a maximum diameter of 20 to 50 μm exceeded 30 pieces / 3 m length × full width.

(Measurement of bright spot foreign matter)
Two polarizing plates were placed in an orthogonal state (crossed Nicols) to block transmitted light, and a cellulose acylate film was placed between the two polarizing plates. At this time, the polarizing plate used was a glass protective plate. The polarizing plate sandwiching the cellulose acylate film was irradiated with light from one side, and the number of bright spots corresponding to the diameter per 1 cm ² was counted with an optical microscope (50 times) from the other side.

(Residual solvent amount)
The cellulose acylate film was cut into 7 mm × 35 mm, and the amount of base residual solvent was measured using gas chromatography (GC-18A, manufactured by Shimadzu Corporation).

(Scratched)
The cellulose acylate film was visually observed, and scratches were evaluated according to the following evaluation criteria.
A: No damage was observed.
B: Slight damage was observed.
C: The damage was considerably recognized.
D: Significant damage was observed.

(Haze)
A cellulose acylate film was cut into a size of 40 mm × 80 mm and 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%.

(Transmittance)
A cellulose acylate film was cut into a size of 20 mm × 70 mm, and the transmittance of visible light (615 nm) was measured at 25 ° C. and a relative humidity of 60% using a transparency measuring device (AKA photoelectric tube colorimeter, KOTAKI Corporation).

(Increased coloring)
The cellulose acylate film was conditioned for 4 hours at 25 ° C. and a relative humidity of 60%. Then, it cut | judged to 5 cm in diameter, was quickly put into the aluminum tray of 5 cm in diameter, and heated at 240 degreeC for 1 hour in the inert oven in an air atmosphere. After cooling, 0.2 g of the sample was dissolved with methylene chloride so that the total volume became 10 ml to prepare a 2 mass% solution, and the absorbance at 400 nm was measured. A 2% by mass methylene chloride solution was also prepared for the sample before heating, and the absorbance at 400 nm was measured, and the increase in absorbance before and after heating was evaluated as an increase in coloring. It shows that it is a film with favorable thermal stability, so that a numerical value is small.

(Alkaline hydrolyzable)
The cellulose acylate film was cut into a size of 100 mm × 100 mm and saponified with a 2 mol / L sodium hydroxide aqueous solution at 60 ° C. for 3 minutes with an automatic alkali saponification apparatus (manufactured by Shinto Kagaku Co., Ltd.). This was washed with water for 4 minutes, then neutralized with 0.01 mol / L dilute nitric acid at 30 ° C. for 4 minutes, and washed with water for 4 minutes. Then, it dried at 100 degreeC for 3 minutes, and also performed natural drying for 1 hour, and evaluated alkali hydrolyzability from the following visual reference | standard and the haze value before and behind a saponification process (25 degreeC and 60% of relative humidity).
A: No whitening was observed.
B: Slight whitening was observed.
C: Fair whitening was observed.
D: Remarkable whitening was observed.

(Curl value)
A cellulose acylate film is cut into a size of 35 mm × 3 mm and adjusted for 24 hours at a relative humidity of 25%, 55% and 85% in a curled humidity tank (HEIDON (No. YG53-168), manufactured by Shinto Kagaku Co., Ltd.). Wet and the radius of curvature was measured with a curl plate. In addition, curling with wet was measured after standing for 30 minutes in water at a water temperature of 25 ° C.

(Kishimi value)
Cellulose acylate films were cut into 100 mm × 200 mm and 75 mm × 100 mm, and conditioned for 2 hours under conditions of 25 ° C. and 60% relative humidity, and put into a Tensilon tensile tester (RTA-100, manufactured by Orientec Co., Ltd.). Then, a large film sample was fixed on a table, and a small film sample with a 200 g weight was placed thereon. Subsequently, the weight was pulled in the horizontal direction, the force at the start of movement and the force at the time of movement were measured, and the static friction coefficient and the dynamic friction coefficient were calculated, respectively, and were set as an artificial kishimi value and a dynamic kishimi value.
F = μ × W (F: Kishimi value, μ: friction coefficient, W: weight of weight (kgf))

(Moisture content)
A cellulose acylate film was cut into a size of 7 mm × 35 mm, and measured by a Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It was calculated by dividing the amount of water (g) by the sample mass (g).

(Heat shrinkage)
A cellulose acylate film is cut out to 30 mm × 120 mm and aged for 24 hours and 120 hours at 90 ° C. and 5% relative humidity. With an automatic pin gauge (manufactured by Shinto Kagaku Co., Ltd.), holes of 6 mmφ are spaced at 100 mm intervals on both ends. And the original size (L1) of the interval was measured to a minimum scale of 1/1000 mm. Further, heat treatment was performed at 90 ° C. and 5% relative humidity for 24 hours and 120 hours, and the dimension (L2) of the punch interval was measured. The thermal contraction rate was determined by {(L1-L2) / L1} × 100.

(Moisture permeability coefficient)
Cellulose acylate film (70 mmφ) was conditioned at 25 ° C./90% relative humidity and 40 ° C./90% relative humidity for 24 hours, respectively, using a moisture permeation tester (KK-709007, manufactured by Toyo Seiki Co., Ltd.). The water content per unit area (g / m ² ) was calculated in accordance with JIS Z-0208. And the moisture permeability was calculated | required by calculating the mass after humidity control-mass before humidity control. As a compulsory evaluation, the moisture permeability coefficient was measured after conditioning for 24 hours at 60 ° C. and 95% relative humidity.

(Elastic modulus)
Using a universal tensile tester STM T50BP manufactured by Toyo Baldwin, the stress at 0.5% elongation was measured in an atmosphere of 23 ° C. and a relative humidity of 70% at a pulling rate of 10% / min to obtain an elastic modulus.

(Tensile strength, elongation rate)
A sample 15 mm × 250 mm was conditioned at 23 ° C. and relative humidity 65% for 2 hours, and in accordance with ISO1184-1983 using a Tensilon tensile tester (RTA-100, Orientec Co., Ltd.), an initial sample length of 100 mm and a tensile speed of 200 The elastic modulus was calculated from the stress and elongation at the initial stage of tension at ± 5 mm / min, and the tensile strength, stretching force, and elongation at break were evaluated.

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

[Synthesis Example 1]
(Synthesis of cellulose acetate propionate)
In a reaction vessel equipped with a stirrer and a cooling device, 80 parts by mass of cellulose (linter) and 33 parts by mass of acetic acid were taken and treated at 60 ° C. for 4 hours to activate the cellulose. 33 parts by mass of acetic anhydride, 518 parts by mass of propionic acid, 536 parts by mass of propionic anhydride and 4 parts by mass of sulfuric acid were mixed, cooled to −20 ° C., and then added to the reaction vessel.

  Esterification was performed so that the maximum temperature of the reaction was 35 ° C., and the time when the viscosity of the reaction solution reached 840 cP was taken as the end point of the reaction. The temperature of the reaction mixture at the end point was adjusted to 15 ° C. The reaction terminator which cooled the mixture of 133 mass parts of water and 133 mass parts of acetic acid to -5 degreeC was added so that the temperature of a reaction mixture might not exceed 23 degreeC.

  The temperature of the reaction mixture was 60 ° C., and the mixture was stirred for 2 hours for partial hydrolysis. The polymer compound obtained by mixing the reaction mixture with an aqueous acetic acid solution was reprecipitated, and washing with warm water at 70 to 80 ° C. was repeated. After the liquid removal, the liquid was immersed in a 0.0012 mass% calcium hydroxide aqueous solution, stirred for 30 minutes, and then liquid removal was performed again. Drying was performed at 70 ° C. to obtain cellulose acetate propionate.

  The obtained cellulose acetate propionate has an acetyl substitution degree of 0.42, a propionyl substitution degree of 2.40, a total acyl substitution degree of 2.82, a number average molecular weight of 50200 (number average polymerization degree DPn = 159), and a weight average molecular weight of 125900. (Weight average polymerization degree DPw = 398), residual sulfuric acid content 55 ppm, magnesium content 10 ppm, calcium content 55 ppm, sodium content 1 ppm, potassium content was below the detection limit and iron content 3 ppm. A powder having a water content of 0.1% by mass, a viscosity of 140 mPa · s of 6% by mass in a dichloromethane solution, an average particle size of 1.2 mm, a standard deviation of 0.3 mm, a bulk specific gravity of 0.21, and a true specific gravity of 1.22. there were. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, no insoluble matter was observed.

[Synthesis Example 2] Synthesis of cellulose acetate propionate 0.1 parts by mass of acetic acid and 2.7 parts by mass of propionic acid were sprayed on 10 parts by mass of cellulose (hardwood pulp) and stored at room temperature for 1 hour. Separately, a mixture of 1.2 parts by mass of acetic anhydride, 61 parts by mass of propionic anhydride, and 0.7 parts by mass of sulfuric acid was prepared, and after cooling to −10 ° C., the mixture was mixed in the reaction vessel with the pretreated cellulose. did.
After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 4 hours. 46 parts by mass of 25% aqueous acetic acid was added to the reaction vessel, the internal temperature was raised to 60 ° C., and the mixture was stirred for 2 hours. 6.2 parts by mass of a solution prepared by mixing equal parts of magnesium acetate tetrahydrate, acetic acid and water was added and stirred for 30 minutes (neutralization step). The reaction solution was filtered under pressure through a sintered metal filter (implemented in two stages with a reserved particle diameter of 40 μm and 10 μm) to remove foreign matters. The reaction solution after filtration was mixed with 75% aqueous acetic acid to precipitate cellulose acetate propionate, and then washed with warm water at 70 ° C. until the pH of the washing solution reached 6-7. Further, the solution was stirred in a 0.001% calcium hydroxide aqueous solution for 0.5 hours and then filtered. The obtained cellulose acetate propionate was dried at 70 ° C. Cellulose acetate propionate obtained from ¹ H-NMR measurement has an acetylation degree of 0.15, a propionylation degree of 2.62, a total acyl substitution degree of 2.77, a number average molecular weight of 54500 (number average polymerization degree DPn = 173). ), Mass average molecular weight 132000 (mass average polymerization degree DPw = 419), residual sulfuric acid content 45 ppm, magnesium content 8 ppm, calcium content 46 ppm, sodium content 1 ppm, potassium content 1 ppm, iron content 2 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no foreign matter was observed when the polarizer was made to go straight or parallel. Films formed using this material are listed in Table 3.

[Synthesis Example 3]
(Synthesis of cellulose acetate butyrate)
In a reaction vessel equipped with a stirrer and a cooling device, 200 parts by mass of cellulose (wood pulp) and 100 parts by mass of acetic acid were taken and treated at 60 ° C. for 4 hours to activate the cellulose. 161 parts by mass of acetic acid, 449 parts by mass of acetic anhydride, 742 parts by mass of butyric acid, 1349 parts by mass of butyric anhydride, and 14 parts by mass of sulfuric acid were mixed and cooled to −20 ° C., and then added to the reaction vessel.

  Esterification was performed so that the maximum temperature of the reaction was 30 ° C., and the time when the viscosity of the reaction solution reached 1050 cP (1050 mPa · s) was defined as the end point of the reaction. The temperature of the reaction mixture at the end point was adjusted to 10 ° C. A reaction stopper obtained by cooling a mixture of 297 parts by mass of water and 558 parts by mass of acetic acid to −5 ° C. was added so that the temperature of the reaction mixture did not exceed 23 ° C.

  The temperature of the reaction mixture was set to 60 ° C., and the mixture was stirred for 2 hours and 30 minutes for partial hydrolysis. The polymer compound obtained by mixing the reaction mixture with an aqueous acetic acid solution was reprecipitated, and washing with warm water at 70 to 80 ° C. was repeated. After removing the liquid, it was immersed in a 0.0025% by mass aqueous calcium hydroxide solution, stirred for 30 minutes, and then removed again. Drying was performed at 70 ° C. to obtain cellulose acetate butyrate.

  The obtained cellulose acetate butyrate has an acetyl substitution degree of 1.51, a butyryl substitution degree of 1.19, a total acyl substitution degree of 2.70, a number average molecular weight of 55,600 (number average polymerization degree DPn = 181), and a weight average molecular weight. 139,000 (weight average polymerization degree DPw = 451), residual sulfuric acid amount 50 ppm, magnesium content 8 ppm, calcium content 65 ppm, sodium content 2 ppm, potassium content 2 ppm, iron content 3 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, no insoluble matter was observed. Films formed using this material are listed in Table 3.

[Synthesis Example 4]
(Synthesis of other cellulose acylates)
For other cellulose acetate propionate and cellulose acetate butyrate, the composition of the acylating agent, the reaction temperature and time of the acylation, the part, depending on the desired degree of substitution and degree of polymerization. The same synthesis was carried out by changing the hydrolysis temperature and time. Films formed using this material are listed in Table 3.

[Synthesis Example 5]
(Synthesis of cellulose mixed ester)
Cellulose acylating agent (selected from acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid, butyric anhydride, depending on the desired degree of acyl substitution) or sulfuric acid as catalyst And the acylation was carried out while maintaining the reaction temperature at 40 ° C. or lower. After the cellulose as a raw material disappeared and acylation was completed, heating was further continued at 40 ° C. or lower to adjust to a desired degree of polymerization. After adding an acetic acid aqueous solution to hydrolyze the remaining acid anhydride, partial hydrolysis was performed by heating at 60 ° C. or lower, and the desired total substitution degree was adjusted. The remaining sulfuric acid was neutralized with an excess amount of magnesium acetate. Reprecipitation was performed from an acetic acid aqueous solution, and further, washing with water was repeated to prepare cellulose acylates having the types of acyl groups and the substitution degree shown in Table 3.

[Example 1]
(1) Preparation of cellulose acylate pellets Cellulose acylate A (Synthesis Example 1) was used as the cellulose acylate. The substitution degree of the acetyl group with respect to the hydroxyl group at the 6-position was 0.15, and the substitution degree of the propionyl group with respect to the hydroxyl group at the 6-position was 0.79, which was 33.3% of the total acetyl. Cellulose acylate A was formed into a solution on a glass plate using methylene chloride / methanol = 90/10 (mass ratio) to obtain a film having a thickness of 80 μm, and its basic characteristics were examined. As a result, the yellow index of the film consisting only of cellulose acylate A is 0.82, haze is 0.1, transmittance is 93.8%, and Tg (glass transition temperature; measured by DSC) is 137 ° C. there were.

  This cellulose acylate A was dried at 105 ° C. for 5 hours to adjust the water content to 0.07% by mass. Subsequently, 1.0 mass% of ultraviolet absorbers (trade name: ADK STAB LA-31, manufactured by Asahi Denka Kogyo Co., Ltd.) was added to the dried cellulose acylate A with respect to the cellulose acylate. Further, silica particles having an average primary particle size of 1.2 μm (the mass abundance ratio of particles of 0.9 to 1.5 μm is 95% or more, and the mass abundance ratio of particles of 1.5 μm or more is 1.0%. Is 0.05% by mass relative to cellulose acylate. Further compounds were added according to Table 1 below. The addition amount of each compound is the mass part of the compound to be used with respect to 100 mass parts of cellulose acylate.

(2) Filtration and pelletization The mixture to which these additives were added was stirred and mixed with a Henschel mixer (manufactured by Mitsui Miike Seisakusho Co., Ltd.) to obtain a uniform cellulose acylate composition. Using this cellulose acylate composition, pellets were produced by an extruder (all the steps were filled with a nitrogen stream). That is, the cellulose acylate composition was charged into a hopper of a biaxial kneading extruder, and further kneaded and melted at 180 to 220 ° C. with a screw rotation speed of 300 rpm and a residence time of 40 seconds. Filtration was performed by pressure filtration using a sintered metal filter having a diameter of 10 μm installed just before the die.

  Further, the filtered melt was extruded from a nozzle having a diameter of 2.5 mm at an extruded portion, and extruded from a die at 200 kg / hour in a strand shape of 3 mm in diameter in a warm water bath at 70 ° C. to 90 ° C. within 3 seconds. After immersion for 30 seconds (strand solidification), the temperature was lowered by passing water at 10 ° C. to 30 ° C. for 30 seconds, and the pellets were obtained by cutting to a diameter of 3 mm and a length of 2 to 6 mm (mostly 3 mm). The obtained cellulose acylate pellets were dried in a nitrogen atmosphere at 105 ° C. for 3 hours, and then packed in a moisture-proof bag made of a laminate film having aluminum in a nitrogen atmosphere, and further stored in a warehouse under a nitrogen atmosphere. Stored with humidity and oxygen blocked. The obtained pellets had a transparent and homogeneous composition.

(3) Melt film formation Next, the cellulose acylate pellets prepared above were dried to a moisture content of 0.01% by mass or less and then put into a hopper adjusted to 95 ° C., and the upstream side melt temperature The melt was melted with a melt extruder adjusted to 195 ° C., intermediate melt temperature 210 ° C., downstream melt temperature shown in Table 1, and T-die temperature 235 ° C. In addition, the diameter of the screw used for this was 60 mm, L / D = 32, and the compression ratio was 8. The resin extruded from the melt extruder is metered and sent out by a gear pump. At this time, the number of revolutions of the extruder is changed so that the resin pressure before the gear pump can be controlled at a constant pressure of 10 MPa. The melt resin delivered from the gear pump is filtered through a leaf disk filter having a filtration accuracy of 5 μm, and is passed through a static mixer from a hanger coat die having a slit interval of 0.8 mm and 230 ° C., glass transition temperatures of Tg−5 ° C., Tg , Extruded onto a triple cast roll set at Tg-10 ° C., brought the Tg-7 ° C. touch roll into contact with the first cast roll on the uppermost stream side, and solidified by pressing with the touch roll shown in Table 1 above. An unstretched film was formed. (This Tg was measured by the above method using DSC). The touch roll was the one described in Example 1 of JP-A-11-235747 (the one described as a double holding roll), and the temperature was adjusted to Tg-7 ° C. (however, the thickness of the thin metal outer cylinder was 3 mm).
The solidified melt is peeled off from the casting drum, both ends (5% each of the total width) are trimmed immediately before winding, and then 10 mm wide and 50 μm high thickness processing (knurling) is applied to both ends, and then 30 m / min. Thus, unstretched films (samples 1-1 to 1-28) having a width of 1.5 m and a length of 3000 m were obtained. The film thickness of each film is as described in Table 2 below. The residual solvent amount was zero. Further, the trimmed end portion was crushed and mixed with a virgin raw material (virgin: crushed = 60: 40 (mass ratio)) to be used as a film forming raw material.

(4) Evaluation The results of measuring and evaluating the Re, Rth, Re unevenness, Rth unevenness, die stripe, planar shape, and number of foreign matters of each cellulose acylate film are shown in Table 2 below.

Sample 1-1, which does not contain any lactone compound, phenol compound, phosphite compound, or thioether compound, had significantly poor Re unevenness, Rth unevenness, dice, and transmittance.
Moreover, the comparison which does not add a lactone type | system | group compound and contains only any one of the compounds selected from the group which consists of a phenolic compound with a molecular weight of 500 or more, or a phosphite compound and a thioether compound with a molecular weight of 500 or more Samples 1-2 to 1-7 had insufficient Re unevenness, Rth unevenness, die stripes, planar shape, the number of foreign matters, and transmittance.

  On the other hand, Samples 1-8 to 1-27 of the present invention have satisfactory levels of Re unevenness, Rth unevenness, die stripes, surface shape, the number of foreign matters and transmittance. A rate film could be obtained. Furthermore, Samples 1-8 to 1-27 of the present invention were excellent in that the transmittance was 91.9% or more and all the haze was 0.3% or less. Also, the humidity dependence of Re {the difference between Re (relative humidity 80%) and Re (relative humidity 10%) at 25 ° C.) is 5 nm or less, and the humidity dependence of Rth {Rth (relative humidity at 25 ° C.) 80%) and Rth (relative humidity 10%)} were all 20 nm or less, which was excellent. The wavelength dispersion characteristics were such that | Re (700) −Re (400) | was within 8 nm and | Rth (700) −Rth (400) | was within 30 nm. The longitudinal and transverse average heat shrinkage of the film (80 ° C./90% relative humidity / 48 hours) was −0.06%, and it was a film that hardly caused heat shrinkage. In the samples 1-8 to 1-27 of the present invention, the increase in coloring is 0.02% or less, and the samples 1-1 to 1-7 are 0.15 to 0.5. It was confirmed that it was excellent. Furthermore, in the samples 1-8 to 1-27 of the present invention, when the molecular weight of cellulose acylate before and after melt film formation was measured, no change in molecular weight was observed.

  Comparative sample 1-28 melted and formed at 245 ° C., which is the melting temperature listed in the examples of Patent Document 2 (Japanese Patent Application Laid-Open No. 2000-352620), has a remarkably bad die streak and deteriorated surface condition and the number of foreign matters. The film was unsuitable for practical use. Further, Comparative Samples 1-2 and 1-3 using the thermal compound IRGNANOX 1010 (PH-2 (AO60)) listed in the examples of Patent Document 3 (Japanese Patent Laid-Open No. 2006-123513) are the present invention. Compared with this sample, the die streak, the surface shape, and the number of foreign matters were remarkably poor, and the film was unsuitable for practical use with significant deterioration in transmittance and coloring. The phenolic compound PH-2 and the phosphite compound PF-5 used in the representative sample 1-13 of the present invention have a mass reduction when heated at 220 ° C. for 30 minutes in nitrogen. Both were 20 mass% or less. In contrast, the phenolic compound (AF-1) and phosphite compound (PA-1) having a molecular weight of less than 500 used in Samples 1-24 and 1-25 were heated at 220 ° C. for 30 minutes in nitrogen. In this case, the mass was reduced to more than 20% by mass and 30% by mass or less.

Here, as a representative of the film sample of the present invention, Sample 1-13 has an inclination width of 19.4 nm, a critical wavelength of 389.2 nm, an absorption edge of 376.1 nm, and an absorption of 380 nm of 1.1%. (Molecular orientation axis) is 0.12 °, elastic modulus is 2.95 GPa in the longitudinal direction, 2.94 GPa in the width direction, tensile strength is 119 MPa in the longitudinal direction, 108 MPa in the width direction, elongation is 62% in the longitudinal direction, width The direction was 67%, the alkali hydrolyzability was A, and the curl value was -0.3 at a relative humidity of 25%, and 1.0 when wet. The moisture content was 1.7% by mass, and the thermal shrinkage was -0.05% in the longitudinal direction and -0.07% in the width direction. The Kishimi value was 0.57, the arithmetic average roughness was 150 nm, the scratches were A rank, and the handling property was satisfactory. Further, no adhesion was observed after application, and the moisture permeability coefficient (550 g / m ² · day) was also good. Other samples of the present invention also showed characteristic values almost equivalent to those of Sample 1-13.

[Example 2]
Except that the cellulose acylate synthesis example 1 in the sample 1-13 of the present invention in Example 1 was changed to cellulose acylate (shown in Table 3 below), the same procedure as in Sample 1-13 in Example 1 was performed. Samples 2-1 to 2-12 of the invention were prepared. The unstretched sample film of the present invention was stretched to the following magnification at 300% / min at Tg + 15 ° C. at the longitudinal and lateral stretching ratios shown in Table 3 below.

  Samples 2-1 to 2-12 of the present invention had good die streak, planar shape, and the number of foreign matters, and were excellent in all of the optical characteristics (Re unevenness, Rth unevenness). From the above, in the present invention, it was confirmed that the degree of polymerization of cellulose acylate and the practical allowable range of substituents are wide.

[Example 3]
(1) Saponification of Cellulose Acylate Film Immersion saponification was performed on the unstretched cellulose acylate films and stretched cellulose acylate films in Tables 1 to 3 by the following procedure. Similar results were obtained when coating saponification was performed according to the following procedure.

(1-1) Immersion Saponification Using a 2.0 mol / L NaOH aqueous solution adjusted to 60 ° C. as a saponification solution, a cellulose acylate film was immersed in the solution for 2 minutes. Then, after being immersed in 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water-washing bath.

(1-2) Coating Saponification 80 parts by mass of water was added to 20 parts by mass of isopropanol, and KOH was dissolved in 2.0 mol / L in this, and the temperature adjusted to 60 ° C. was used as a saponification solution. This saponification solution was applied onto a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, hot water at 50 ° C. was sprayed at 10 L / m ² · min for 1 minute for washing.

(2) Production of Polarizer According to Example 1 of JP 2001-141926 A, a peripheral speed difference was given between two pairs of nip rolls, and a polarizer having a thickness of 20 μm was prepared by stretching in the longitudinal direction.

(3) Bonding The polarizer thus obtained and the saponified unstretched and stretched cellulose acylate film and the saponified unstretched triacetate film (Fuji Photo Film Co., Ltd., Fujitac) (Made by Kuraray Co., Ltd., PVA-117H) 3% by weight aqueous solution as an adhesive, and pasted together in the film forming flow direction (longitudinal method) of the polarizer and the cellulose acylate in the following combinations, A polarizing plate was obtained.
Polarizing plate A: unstretched cellulose acylate film / polarizer / Fujitac (TD80UL)
Polarizing plate B: Unstretched cellulose acylate film / polarizer / unstretched cellulose acylate film Polarizing plate C: Unstretched cellulose acylate film / polarizer / stretched cellulose acylate film Polarizing plate D: Stretched cellulose acylate film / polarized light Child / Fujitac (TD80UL)

(4) Evaluation After attaching the obtained polarizing plate to a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261 at 25 ° C. and 60% relative humidity, Bring it into 25 ° C and 10% relative humidity, visually evaluate the change in color tone by a 10-step evaluation (the larger the change, the greater the change), visually evaluate the area where the display unevenness occurs, and display unevenness The percentage (%) at which occurrence occurred. As a result, the cellulose acylate films of Samples 1-8 to 1-27 and Samples 2-1 to 2-12 of the present invention have a color tone change of 1 to 4 and display unevenness is 5% or less. It was very good. On the other hand, in comparative samples 1-1 to 1-7 and 1-28 outside the present invention, the color tone change was 7 to 10, the display unevenness was 30% or more, and the visibility was inferior. Further, according to Example 1 of JP-A-2002-86554, the cellulose acylate film of the present invention is similarly applied to a polarizing plate stretched using a tenter so that the stretching axis is at an angle of 45 ° with respect to the absorption axis. Although it was used, good results were obtained as described above.

[Example 5]
Instead of the cellulose triacetate film sample 1401 in Example 14 described in JP-A-2002-265636, the cellulose acylate film sample 1-13 of the present invention produced in Example 1 was used. Then, an optically anisotropic layer and a polarizing plate sample were prepared in exactly the same manner as in Example 14 described in JP-A No. 2002-265636 to prepare a TN type liquid crystal cell. The obtained liquid crystal cell had excellent viewing angle characteristics.

[Example 6]
(Mounting on VA panel)
The polarizing plate produced in Example 4 of the present invention is such that the polarizing plate on the viewing side has a short absorption axis of the polarizer so that the polarizing plate on the viewing side is 26 "wide and the absorption axis of the polarizer is long. Punched into a rectangular shape so that the sides of the VA mode liquid crystal TV (Sony Co., Ltd., KDL-L26RX2) are peeled off, and the cellulose acylate film of the present invention is used on the front and back sides. A polarizing plate produced in this manner was attached to produce a liquid crystal display device, which was held and bonded at 50 ° C. and 5 kg / cm ² for 20 minutes after being attached. The axis is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the adhesive material surface is on the liquid crystal cell side. EZ-Contrast 16 D) was used to calculate the viewing angle (contrast ratio in the range of 10 or more) from the luminance measurement of black display and white display, and good polar angle of 80 ° or more in all directions when any polarizing plate was used. Furthermore, the light leakage, display unevenness, and polarizing plate peeling test by the durability test were performed, and samples 1-8 to 1-27 and 2-1 to 2- It was confirmed that there was no problem using the cellulose acylate film No. 12. The durability test conditions were as follows.
1) Hold in an environment of 60 ° C and 90% relative humidity for 200 hours, take out in an environment of 25 ° C and 60% relative humidity, and display the liquid crystal display device in black 24 hours later, light leakage strength and peeling of the polarizing plate from the liquid crystal panel The presence or absence of was evaluated.
2) Hold in an environment of 80 ° C. and relative humidity of 10% or less for 200 hours, take out into an environment of 25 ° C. and relative humidity of 60%, and display the liquid crystal display device black after 1 hour. The presence or absence of peeling was evaluated.

[Example 7]
A sample of the present invention is produced on an optically anisotropic film exhibiting desired optical characteristics, and a commercially available monitor of a different liquid crystal mode or a retardation film of a television is peeled off, and the optical compensation film of the present invention is attached to the field of view. As a result of investigating the angular characteristics, it was confirmed that the cellulose acylate of the present invention was useful by obtaining excellent wide viewing angle characteristics and colors.

(TN mode)
Both the viewing-side polarizing plate and the backlight-side polarizing plate were punched into a rectangle so that the absorption axis was 45 ° long with respect to the long side of the punched polarizing plate having a size of 17 ″. TN mode liquid crystal The polarizing plates on the front and back of the monitor (manufactured by Samsung, SyncMaster 172X) and the retardation plate were peeled off, and the polarizing plates made of the cellulose acylate of the present invention were attached to the front and back sides in combination to produce a liquid crystal display device. After pasting the polarizing plate, it was held and bonded for 20 minutes at 50 ° C. and 5 kg / cm ^2, where the optically anisotropic layer of the polarizing plate faces the cell substrate and faces the rubbing direction of the liquid crystal cell. It arrange | positioned so that the rubbing direction of an optically anisotropic layer might become antiparallel.

(IPS panel)
The polarizing plate of the present invention is such that the viewing side polarizing plate is 32 "wide and the absorption axis of the polarizer is long, and the backlight side polarizing plate is rectangular so that the absorption axis of the polarizer is short. Polarized light produced from the cellulose acylate of the present invention on the front and back sides of the IPS mode liquid crystal TV (W32-L5000, manufactured by Hitachi, Ltd.) by peeling off the front and back polarizing plates and the retardation plate. A liquid crystal display device was prepared by combining the plates, and after being attached to the polarizing plate, it was held and bonded at 50 ° C. and 5 kg / cm ² for 20 minutes, with the absorption axis of the polarizing plate on the viewing side being the panel. In the horizontal direction, the polarizing plate on the backlight side was arranged so that the absorption axis was in the panel vertical direction and the adhesive layer surface was on the liquid crystal cell side.

[Example 8]
In the preparation of cellulose acylate pellets (1) in the cellulose acylate film sample 1-13 of the present invention of Example 1, except that 5 mass% of FP700 (Asahi Denka Co., Ltd.) is added as a plasticizer to the cellulose acylate. The cellulose acylate film sample 3-1 of the present invention was produced in exactly the same manner as the cellulose acylate film sample 1-13.
The resulting cellulose acylate film did not show any smoke during film formation, and was excellent in all respects such as die streak, surface shape, number of foreign matters, and optical characteristics (Re unevenness, Rth unevenness). In particular, it was confirmed that the cellulose acylate film sample 3-1 was excellent while the moisture content was 1.7% and the non-added was 2.2%. Therefore, it was confirmed that the plasticizer is effective in improving the physical properties of the cellulose acylate film.

[Example 9]
(Production of low reflection film)
Using the cellulose acylate film of the present invention, a low reflection film was produced according to Example 47 of the Japan Society for Invention and Innovation (Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). It had optical performance.

[Example 10]
Preparation of Optical Compensation Film A liquid crystal layer was applied to the cellulose acylate film of the present invention according to Example 1 of JP-A-11-316378, and a good optical compensation film was obtained.

[Example 11]
The cellulose acylate film sample 1-13 of the present invention produced in Example 1 was used in place of the cellulose triacetate film sample 1301 in Example 13 described in JP-A No. 2002-265636. Then, an optically anisotropic layer and a polarizing plate sample were prepared in exactly the same manner as in Example 13 described in JP-A No. 2002-265636, thereby preparing a bend alignment liquid crystal cell. The obtained liquid crystal cell had excellent viewing angle characteristics.

  According to the present invention, a cellulose acylate having a good surface shape, an extremely small number of foreign matters, and capable of suppressing changes in visibility due to image unevenness and humidity generated on a display screen when incorporated in a liquid crystal display device. Can be provided. In addition, the cellulose acylate film of the present invention can provide a film for optical use having weather resistance over time, particularly excellent durability under a high temperature environment. The liquid crystal display device manufactured by incorporating the cellulose acylate film of the present invention can suppress display unevenness, changes in optical characteristics due to humidity or image color. From the above, the cellulose acylate film of the present invention has very high industrial applicability.

It is the schematic which showed the example of the apparatus for implementing melt film forming using the cellulose acylate pellet in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Kneading extruder 102 Gear pump 103 Filtration part 104 Die 105 Touch roll 106 Casting cooling drum 107 Cellulose acylate 108 Longitudinal stretch process part 109 Lateral stretch process part 110 Winding process part

Claims (16)

Cellulose acylate satisfying the following formulas (S-1) to (S-3) and at least one lactone compound represented by the following general formula (II) are 0.01 to A cellulose acylate composition containing 3% by mass.
Formula (S-1) 2.5 ≦ X + Y ≦ 3.0
Formula (S-2) 0 ≦ X ≦ 2.2
Formula (S-3) 0.8 ≦ Y ≦ 3.0
(In the formula, X represents the substitution degree of the acetyl group to the hydroxyl group of cellulose, and Y represents the total substitution degree of the acyl group having 3 to 22 carbon atoms to the hydroxyl group of cellulose.)

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. Show.)   At least one selected from the group consisting of a phosphite compound having a molecular weight of 500 or more and a thioether compound having a molecular weight of 500 or more, and a phenol compound having a molecular weight of 500 or more to the cellulose acylate The cellulose acylate composition according to claim 1, wherein the cellulose acylate composition is contained in an amount of 0.01 to 3% by mass.   The cellulose acylate composition according to claim 1 or 2, which is in a pellet form.   A method for producing a cellulose acylate film, comprising a step of melting and casting the cellulose acylate composition according to claim 1.   3. A step of melting the cellulose acylate composition according to claim 1 or 2 at 150 to 240 ° C. to produce a pellet, melting the pellet and extruding from a die at 180 to 240 ° C. to form a cast film. A method for producing a cellulose acylate film, comprising: 6. The process for producing a cellulose acylate film according to claim 4 or 5, further comprising a step of forming a film by pressing the touch roll at 0.1 to 10 MPa after casting the cellulose acylate composition. Method.   The method for producing a cellulose acylate film according to any one of claims 4 to 6, further comprising a step of stretching 1% to 300% in at least one direction after the film formation.   The cellulose acylate film manufactured by the manufacturing method of any one of Claims 4-7. 0.01-3 masses of cellulose acylate satisfying the following formulas (S-1) to (S-3) and at least one lactone compound represented by the following general formula (II) with respect to the cellulose acylate %, And the amount of residual solvent is 0.01% by mass or less.
Formula (S-1) 2.5 ≦ X + Y ≦ 3.0
Formula (S-2) 0 ≦ X ≦ 2.2
Formula (S-3) 0.8 ≦ Y ≦ 3.0
(In the formula, X represents the substitution degree of the acetyl group to the hydroxyl group of cellulose, and Y represents the total substitution degree of the acyl group having 3 to 22 carbon atoms to the hydroxyl group of cellulose.)

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms or an aryl group having 6 to 15 carbon atoms. Show.)   The cellulose acylate film is at least one selected from the group consisting of a phosphite compound having a molecular weight of 500 or more and a thioether compound having a molecular weight of 500 or more; and a phenolic compound having a molecular weight of 500 or more; The cellulose acylate film according to claim 9, wherein the cellulose acylate is contained in an amount of 0.01 to 3 mass% with respect to the cellulose acylate.   The cellulose acylate film according to claim 8, wherein the film thickness is 20 μm to 300 μm.   The front retardation (Re) is 0 to 300 nm, and the absolute value of retardation (Rth) in the thickness direction is 0 to 700 nm. Cellulose acylate film.   A polarizing plate comprising at least one layer of the cellulose acylate film according to any one of claims 8 to 12 laminated on a polarizer.   An optical compensation film comprising the cellulose acylate film according to any one of claims 8 to 12.   An antireflection film comprising the cellulose acylate film according to any one of claims 8 to 12.   It consists of the cellulose acylate film of any one of Claims 8-12, the polarizing plate of Claim 13, the optical compensation film of Claim 14, and the antireflection film of Claim 15. A liquid crystal display device using at least one selected from the group.

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