JP2007002215A - Cellulose acylate film and method for producing the same, polarizing plate using the same, optical compensation film for liquid crystal display, antireflection film and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film having proper water permeability, excellent in adhesiveness with polarizing films, having small contact angle after saponification, brought to have contact angle difference in a face or both faces and able to satisfy time dependent stability of degree of polarization required in high temperature and high humidity environment and good adhesiveness. <P>SOLUTION: The cellulose acylate film is produced by melting/casting, has 150-800 g/(m<SP>2</SP>24hr) water permeability at 40°C and 95% relative humidity and satisfies following equations (1)-(3): equation (1), 2.0≤X+Y≤3.0; equation (2), 0≤X≤2.0; equation (3), 1.2≤Y≤3.0; X expresses degree of substitution of acetyl groups; Y expresses total degree of substitution of 3-7C acyl groups. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cellulose acylate film formed by melt casting and a method for producing the same. The present invention also relates to a polarizing plate, an optical compensation film, an antireflection film, and a liquid crystal display device that are excellent in durability using the cellulose acylate film.

  The cellulose acylate film is used in a support of a halogenated photographic light-sensitive material, a retardation plate, a support of a retardation plate, a protective film for a polarizing plate, and a liquid crystal display device. Among these, the cellulose triacetate (TAC) film, which is most commonly used for optical applications such as liquid crystal display devices, is saponified by immersing the surface in an alkaline aqueous solution and taking advantage of the characteristics having an appropriate moisture permeability. Therefore, it can be directly applied to a polarizing film containing polyvinyl alcohol as a main component. However, the TAC film has high moisture permeability and water absorption. Therefore, a polarizing plate using a TAC film as a protective film, when used in fields requiring high reliability for heat resistance and moisture resistance, such as for outdoor use and in-vehicle use, has optical characteristics due to excessive water penetration. It has been a problem that the deterioration of the material is large.

  Moreover, when manufacturing a cellulose acetate film, the solution casting method which melt | dissolves in a chlorinated organic solvent like a dichloromethane, casts this on a base material, dries and forms into a film is mainly implemented. Dichloromethane (boiling point of about 40 ° C.) used as a chlorinated organic solvent is conventionally known as a good solvent for cellulose acylate, and has the advantage of being easy to dry because of its low boiling point in the film formation and drying steps of the production process. It is preferably used because of having it. In recent years, chlorinated organic solvents having a low boiling point from the viewpoint of environmental protection have been able to significantly reduce leakage in handling processes even in sealed facilities. For example, a thorough closed system was used to prevent leakage from the system, and in the unlikely event of leakage, a gas absorption tower was installed before adsorbing the organic solvent before processing to the outside air. Furthermore, almost no organic solvents are discharged by burning with thermal power or decomposition of chlorinated organic solvents by electron beam before discharging, but further research is required before complete discharge.

  As a countermeasure for preventing such discharge of the organic solvent, a method of melt-forming cellulose acylate without using the organic solvent has been proposed (see, for example, Patent Document 1 and Patent Document 2). In this method, the melting point is lowered by elongating the carbon chain of the ester group of cellulose acylate to facilitate melt film formation. Specifically, melt film formation is enabled by changing from cellulose acetate to cellulose acetate propionate, cellulose acetate butyrate, or the like. In addition, when these cellulose acylates having a long carbon chain are used, a certain effect of reducing the water content and the water permeability can be obtained.

  However, a polarizing plate produced according to the example of Patent Document 2 described above as a polarizing plate protective film obtained by melt film formation by these methods is insufficient in the adhesive strength between the cellulose acylate film and the polarizing film, or high temperature. There is a problem in that the degree of polarization decreases under a high humidity environment, and peeling occurs from the polarizing film when placed in a humid heat environment or when immersed in warm water, and an improvement is urgently required.

Japanese National Patent Publication No. 6-501040 JP 2000-352620 A

  In the present invention, the polarizing plate using the melt-formed cellulose acylate film has a high degree of polarization and high transmittance, and even when used in a high temperature and high humidity environment, the degree of polarization is reduced or polarized. Cellulose acylate film excellent in durability and adhesiveness without peeling off from film and production method thereof, and polarizing plate, optical compensation film for liquid crystal display device, antireflection film and liquid crystal display device using the same It is to provide.

  The present inventor has found that the above-described poor adhesion between the cellulose acylate film and the polarizing film is insufficient in imparting saponification suitability to the surface of the cellulose acylate film, and the contact angle of water in and out of the film surface is poor. It was clarified that it was caused by uniformity. As a result of diligent advancement based on this idea, by using cellulose acylate whose contact angle and distribution satisfy certain conditions, the adhesive strength between the melt-formed cellulose acylate film and the polarizing film has been dramatically improved. It was found that it can be improved.

  In addition, as a result of various investigations on the melt film-forming conditions of the cellulose acylate film, the cellulose acylate film was formed by controlling the drum surface temperature and the left-right temperature distribution using a multiple casting drum having a plurality of casting drums. The uniformity of physical properties on both sides of the film is improved, and when the alkali saponification treatment is performed, the difference in the contact angle between both sides of the film is reduced, and the difference in adhesiveness with the polarizing film can be eliminated by using either side. I found it.

  Furthermore, surprisingly, the film formed by the melt casting with the above-mentioned multiple casting drum has an effect of lowering the water permeability as compared with the film produced by the usual melt casting. For this reason, even when the polarizing plate using this was used in a high-temperature, high-humidity environment, it discovered that there was no fall of a polarization degree and was excellent in durability, and resulted in this invention. In particular, by using in combination with such a multiple casting method and a touch roll film forming method described later, a film having an excellent effect of reducing the water permeability and the effect of improving the durability of the polarizing plate is obtained. can get. A liquid crystal display device using a polarizing plate in which a film having such performance is incorporated has a very good image.

That is, the said subject is achieved by this invention which has the following structures.
(1) It is formed by melt casting, has a water permeability of 150 to 800 g / m ² · 24 hr at 40 ° C. and a relative humidity of 95%, and satisfies the following formulas (1) to (3): Cellulose acylate film.
Formula (1): 2.0 ≦ X + Y ≦ 3.0
Formula (2): 0 ≦ X ≦ 2.0
Formula (3): 1.2 ≦ Y ≦ 3.0
[Wherein, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 7 carbon atoms. ]

(2) The cellulose reed according to (1), which has been subjected to an alkali saponification treatment, has a water contact angle of 45 ° or less, and has a difference in in-plane distribution of contact angles within 5 °. Rate film.

(3) The cellulose acylate film as described in (2), wherein the difference between the contact angles on both sides of the film is within 5 °.

(4) The in-plane retardation (Re) of the unstretched cellulose acylate film is 0 ≦ Re ≦ 20 nm, and the retardation in the thickness direction (Rth) is 0 ≦ Rth ≦ 60 nm. The cellulose acylate film according to any one of (1) to (3).

(5) After stretching the cellulose acylate film according to any one of (1) to (4) by 1 to 250% in at least one direction, the in-plane retardation (Re) is 0 ≦ Re ≦ 300 nm, In addition, the cellulose acylate film according to any one of (1) to (4), wherein retardation in the thickness direction (Rth) is 0 ≦ Rth ≦ 500 nm.

(6) A method for producing a cellulose acylate film, wherein a cellulose acylate is formed into a film by melt casting using a multiple casting drum provided with a plurality of casting drums,
The surface temperature of the first casting drum on which the cellulose acylate extruded from the die is melt cast is (Tg-30) ° C. to (Tg + 15) ° C., and the casting drum is at the temperature at both ends of the roll surface. The cellulose acylate film manufacturing method, wherein the difference is 10 ° C. or less.

(7) The method for producing a cellulose acylate film according to (6), wherein the film is formed using a touch roll.
(8) The cellulose acylate according to (6) or (7), wherein the film-like cellulose acylate formed by the multiple casting drum is subjected to an alkali saponification treatment at a temperature of 41 to 80 ° C. A method for producing a rate film.

(9) The cellulose acylate film according to any one of (1) to (5), which is produced by the method for producing a cellulose acylate film according to any one of (6) to (8).

(10) A polarizing plate, wherein at least one layer of the cellulose acylate film according to any one of (1) to (5) or (9) is laminated on a polarizing film.

(11) The polarizing plate according to (10), wherein the transmittance is 42.0% or more and the degree of polarization is 99.0% or more.

(12) The polarizing plate according to (10) or (11), wherein the degree of polarization reduction after holding for 1000 hours in an environment of 80 ° C. and 90% relative humidity is 1% or less.

(13) An optical compensation film using the cellulose acylate film according to any one of (1) to (5) or (9).

(14) An antireflection film comprising the cellulose acylate film according to any one of (1) to (5) or (9).

(15) The cellulose acylate film according to any one of (1) to (5) and (9), the polarizing plate according to any one of (10) to (12), and the optical compensation film according to (13) A liquid crystal display device comprising one or more films selected from the group consisting of the antireflection films according to (14).

  According to the present invention, it has an appropriate water permeability, excellent adhesion to a polarizing film, a small contact angle of water after saponification treatment, and a small difference in contact angle between in-plane or both surfaces. In addition, it is possible to provide a cellulose acylate film capable of satisfying the temporal stability of polarization degree and good adhesion required in a high temperature and high humidity environment, and a method for producing the same. Further, according to the present invention, it is possible to provide a high-quality polarizing plate, an optical compensation film having a polarizing plate protection function and a retardation compensation function, an antireflection film, and a liquid crystal display device using these.

  Hereinafter, the cellulose acylate film and the production method, the polarizing plate, the optical compensation film for liquid crystal display device, the antireflection film and the liquid crystal display device of the present invention 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.

<< Characteristics of Cellulose Acylate Film of the Present Invention >>
The cellulose acylate film of the present invention is formed by melt casting, has a water permeability of 150 to 800 g / m ² · 24 hr at 40 ° C. and a relative humidity of 95%, and has the following formulas (1) to (3): It is characterized by satisfaction.
Formula (1): 2.0 ≦ X + Y ≦ 3.0
Formula (2): 0 ≦ X ≦ 2.0
Formula (3): 1.2 ≦ Y ≦ 3.0
[Wherein, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 7 carbon atoms. ]

  The method for producing a cellulose acylate film of the present invention is a method for producing a cellulose acylate film in which a cellulose acylate is formed into a film by melt casting using a multiple casting drum provided with a plurality of casting drums. The surface temperature of the first casting drum on which the cellulose acylate extruded from the die is melt cast is (Tg-30) ° C. to (Tg + 15) ° C., and the plurality of casting drums are rolls The difference in temperature between both ends of the surface is preferably 10 ° C. or less.

[Water permeability]
The water permeability of the cellulose acylate film which is one of the characteristics of the present invention is 150 to 800 g / m ² · 24 hr (at 40 ° C. and 95% relative humidity), and 200 to 800 g / m ² · 24 hr. Is more preferable, and 250 to 750 g / m ² · 24 hr is more preferable.
And most preferably 250 to 700 g / m ² · 24 hr. When the water permeability of the cellulose acylate film is less than 150 g / m ² · 24 hr, the water in the polarizing film and the adhesive is not sufficiently evaporated through the cellulose acylate film in the adhesive drying process. As a result, the moisture content increases, and as a result, sufficient adhesive strength is difficult to obtain, and the polarizing performance and durability of the obtained polarizing plate deteriorate. On the other hand, when the water permeability exceeds 800 g / m ² · 24 hr, the durability of the obtained polarizing plate in a high temperature and high humidity (80 ° C., relative humidity 90%) environment is deteriorated.

[Contact angle of water]
Moreover, it is preferable that the cellulose acylate film of this invention has a small contact angle of the water after a saponification process. From the viewpoint of improving the bonding property with the hydrophilic polarizing film, the contact angle of water after the saponification treatment is preferably 45 ° or less, more preferably 40 ° or less, further preferably 35 ° or less, and most preferably 30 ° or less. When the contact angle of water after saponification is 45 ° or less, the adhesion between the cellulose acylate film and the polarizing film is high, and the degree of polarization and the peeling from the polarizing film are prevented in a high temperature and high humidity environment. be able to.

  Regarding the water contact angle, after the cellulose acylate film was conditioned at 25 ° C. and a relative humidity of 60% for 3 hours or more, a drop of pure water having a diameter of 3 mm was dropped on the surface of the film, The contact angle of water can be obtained from the angle formed by

  The cellulose acylate film of the present invention preferably has an in-plane distribution of contact angles and a difference in double-side contact angles within 5 °, more preferably 4 ° or less, after saponification treatment on both sides. More preferably, it is 3 ° or less. In this way, by improving the uniformity of the in-plane and out-of-plane contact angles, the adhesion between the cellulose acylate film of the present invention and the polarizing film is uniformly made uniform, and it is localized in a high temperature and high humidity environment. Good durability can be obtained without causing problems such as peeling of the film and lowering of the degree of local polarization.

Such water permeability and water contact angle are achieved by adjusting the cellulose acylate material, melt film forming conditions (casting conditions) and saponification conditions described later within the scope of the present invention.
In the following, detailed description will be added in the order of the cellulose acylate material, the melt film forming conditions (casting conditions) and the saponification conditions.

≪Cellulose acylate material≫
The acylate group of the cellulose acylate used in the present invention satisfies the following formulas (1) to (3).
Formula (1): 2.0 ≦ X + Y ≦ 3.0
Formula (2): 0 ≦ X ≦ 2.0
Formula (3): 1.2 ≦ Y ≦ 3.0
[Wherein, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 7 carbon atoms. ]

  The cellulose acylate in the present invention preferably satisfies all of the following formulas (4) to (6), and particularly preferably satisfies all of the following formulas (7) to (9).

Formula (4): 2.4 ≦ X + Y ≦ 3.0
Formula (5): 0.05 ≦ X ≦ 1.8
Formula (6): 1.3 <= Y <= 2.99

Formula (7): 2.5 ≦ X + Y ≦ 2.95
Formula (8): 0.1 ≦ X ≦ 1.6
Formula (9): 1.4 ≦ Y ≦ 2.95

  Among the acyl groups having 3 to 7 carbon atoms that are the target of Y, which is the degree of substitution of the acyl group having 3 to 7 carbon atoms, preferred are propionyl group, butyryl group, 2-methylpropionyl group, pentanoyl group, 3 -Methylbutyryl group, 2-methylbutyryl group, 2,2-dimethylpropionyl (pivaloyl) group, hexanoyl group, 2-methylpentanoyl group, 3-methylpentanoyl group, 4-methylpentanoyl group, 2,2-dimethylbutyryl Examples include a ryl group, a 2,3-dimethylbutyryl group, a 3,3-dimethylbutyryl group, a cyclopentanecarbonyl group, a heptanoyl group, a cyclohexanecarbonyl group, and a benzoyl group, and more preferably a propionyl group and a butyryl group. Group, pentanoyl group, hexanoyl group, benzoyl group, particularly preferably propio Group, a butyryl group, most preferably a propionyl group. The acyl group constituting the cellulose acylate used in the present invention may be a single species or a plurality of species.

  Next, the manufacturing method of the cellulose acylate in this invention is demonstrated in detail. The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968). In addition, the raw material cotton and the synthesis method of the cellulose acylate of the present invention are also described in detail on pages 7 to 12 of the Japan Institute of Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society of Invention). The description is also applicable.

(material)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As the cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 to 99.9% by mass.

(activation)
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) for contact with an activator. As the activator, carboxylic acid or water can be used. The addition method can be selected from methods such as spraying, dropping, and dipping.

  Preferred carboxylic acids as activators are carboxylic acids having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, benzoic acid, etc.), more preferably acetic acid, propionic acid, or butyric acid, particularly preferably. Is acetic acid. At the time of activation, an acylation catalyst such as sulfuric acid may be added in an amount of 0.1% by mass to 10% by mass with respect to the cellulose, if necessary. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but it is preferably 100 times or less, more preferably 20 times or less, and 10 times or less by mass with respect to cellulose. It is particularly preferred that

The activation time is preferably 20 minutes or more, and the upper limit is not particularly limited as long as it does not affect productivity, but is preferably 72 hours or less, more preferably 24 hours or less, particularly preferably. 12 hours or less. The activation temperature is preferably 0 ° C to 90 ° C, more preferably 15 ° C to 80 ° C, and particularly preferably 20 ° C to 60 ° C.

(Acylation)
In the method for producing cellulose acylate in the present invention, it is preferable to acylate a hydroxyl group of cellulose by reacting cellulose and a carboxylic acid anhydride with Bronsted acid or Lewis acid as a catalyst.

As a method for obtaining a cellulose mixed acylate, a method of reacting two carboxylic acid anhydrides as an acylating agent by mixing or sequentially adding them, a mixed acid anhydride of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride) Product), mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in the reaction system using carboxylic acid and another carboxylic acid anhydride (for example, acetic acid and propionic acid anhydride) as raw materials And a method in which cellulose acylate having a substitution degree of less than 3 is once synthesized, and a remaining hydroxyl group is further acylated using an acid anhydride or acid halide. .
The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in JP-A-11-5851, JP-A-2002-212338, JP-A-2002-338601, and the like.

(Acid anhydride)
The acid anhydride of the carboxylic acid preferably has 2 to 7 carbon atoms as the carboxylic acid, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, benzoic anhydride, and the like. Can do. More preferred are acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, and particularly preferred are acetic anhydride, propionic anhydride, butyric anhydride.
The acid anhydride is usually added in excess equivalent to the cellulose. That is, it is preferable to add 1.1-50 equivalent with respect to the hydroxyl group of a cellulose, It is more preferable to add 1.2-30 equivalent, It is especially preferable to add 1.5-10 equivalent.

(catalyst)
It is preferable to use a Bronsted acid or a Lewis acid as the acylation catalyst used in the production of cellulose acylate in the present invention. The definitions of Bronsted acid and Lewis acid are described in, for example, “Physical and Chemical Dictionary”, 5th edition (2000). As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. The preferable addition amount of a catalyst is 0.1-30 mass% with respect to a cellulose, More preferably, it is 1-15 mass%, Most preferably, it is 3-12 mass%.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring property, acyl substitution ratio, and the like. The solvent is preferably a carboxylic acid, and more preferably a carboxylic acid having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, hexanoic acid, benzoic acid). Particularly preferred are acetic acid, propionic acid, butyric acid and the like. These solvents may be used as a mixture.

(Conditions for acylation)
The acylating agent may be added to the cellulose all at once or in divided portions. In addition, cellulose may be added to the acylating agent all at once or in divided portions. In order to control the temperature rise in the reaction vessel due to the heat of reaction during acylation, the acylating agent is preferably cooled in advance.

  In the method for producing the cellulose acylate of the present invention, it is preferable that the maximum temperature reached during acylation is 50 ° C. or lower. More preferably, it is 40 degrees C or less, Most preferably, it is 35 degrees C or less. The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher.

The reaction time for acylation is preferably 0.5 hours to 24 hours, more preferably 1 hour to 12 hours, and particularly preferably 1.5 hours to 10 hours.
The end point of acylation can be determined by means such as light transmittance, solution viscosity, temperature change of reaction system, solubility of reactant in organic solvent, microscopic observation, etc., depending on the desired degree of substitution and polymerization. it can.

(Reaction terminator)
In the method for producing cellulose acylate used in the present invention, it is preferable to add a reaction terminator after the acylation reaction.
The reaction terminator may be any as long as it decomposes the acid anhydride, and preferable examples include water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing these. However, a mixture of water and carboxylic acid (acetic acid, propionic acid, butyric acid, etc.) is more preferred, and acetic acid is particularly preferred as the carboxylic acid. The composition ratio of water and carboxylic acid can be used at any ratio, but the water content is 5% by mass to 80% by mass, further 10% by mass to 60% by mass, and particularly 15% by mass to 50% by mass. % Is preferable.

(Neutralizer)
Hydrolysis of excess carboxylic anhydride remaining in the system after the acylation reaction stopping step or acylation reaction stopping step, neutralization of some or all of the carboxylic acid and esterification catalyst, residual sulfate radical amount In order to adjust the amount of residual metal and the like, a neutralizing agent or a solution thereof may be added.
Preferred examples of the neutralizing agent include ammonium, organic quaternary ammonium, alkali metal, group 2 metal, group 3-12 metal, or group 13-15 element carbonate, bicarbonate, organic acid salt. (For example, acetate, propionate, butyrate, benzoate, phthalate, hydrogen phthalate, citrate, tartrate, etc.), hydroxide or oxide can be used.
More preferably, the neutralizing agent is a carbonate, bicarbonate, organic acid salt, hydroxide or oxide of an alkali metal or a group 2 metal, and particularly preferably sodium, potassium, magnesium or calcium. , Carbonates, bicarbonates, acetates or hydroxides.
Preferred examples of the neutralizing agent solvent include water, organic acids (for example, acetic acid, propionic acid, butyric acid, and the like) and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate thus obtained has a total degree of substitution close to 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, acylation of remaining sulfuric acid or the like) is performed. (Catalyst) and water in the presence of 20 to 90 ° C. for several minutes to several days to partially hydrolyze the ester bond and reduce the acyl substitution degree of cellulose acylate to a desired level (so-called Aging) is generally performed.

  When the desired cellulose acylate is obtained, it is preferable to completely neutralize the catalyst remaining in the system using the neutralizing agent as described above or a solution thereof to stop partial hydrolysis. . By adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate, etc.) that generates a salt that is poorly soluble in the reaction solution, a catalyst (for example, sulfate ester) bound to the solution or to cellulose is effectively removed. It is also preferable to remove.

(Filtration)
The reaction mixture (dope) is preferably filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose acylate. Filtration may be performed in any step from completion of acylation to reprecipitation. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose acylate solution thus obtained is mixed in a poor solvent such as water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.), or the poor solvent is mixed in the cellulose acylate solution. Thus, the cellulose acylate can be re-precipitated, and the desired cellulose acylate can be obtained by washing and stabilizing treatment. The reprecipitation may be carried out continuously or batchwise by a fixed amount.

(Washing)
The produced cellulose acylate is preferably washed. Any washing solvent may be used as long as it has low solubility of cellulose acylate and can remove impurities, but water or warm water is usually used. The progress of washing may be traced by any means, but preferable examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, atomic absorption spectrum, and sensory inspection of carboxylic acid odor. Can do.

(Stabilization)
The cellulose acylate after washing is preferably treated with a stabilizer or an aqueous solution thereof in order to further improve the stability or reduce the carboxylic acid odor.
Examples of the stabilizer include weak alkalis. For example, carbonates such as sodium, potassium, calcium, magnesium, and aluminum, bicarbonates, hydroxides, oxides, and the like are preferable.

(Dry)
In the present invention, in order to adjust the water content of the cellulose acylate to a preferable amount, it is preferable to dry the cellulose acylate. The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 50 to 160 ° C. The cellulose acylate of the present invention has a water content of preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

  The degree of polymerization of the cellulose acylate preferably used in the present invention is an average degree of polymerization of 100 to 700, preferably 120 to 550, more preferably 120 to 400, and particularly preferably an average degree of polymerization of 130 to 350. The average degree of polymerization is determined by gel permeation chromatography (GPC) as described in Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). ) To measure the molecular weight distribution. Furthermore, the method for measuring the average degree of polymerization is described in detail in JP-A-9-95538.

  The cellulose acylate used in the present invention preferably has a mass average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 1.5 to 5.0, and more preferably. Is 2.0 to 4.5, and more preferably 2.0 to 4.5 cellulose acylate is used.

These cellulose acylates may be used alone or in combination of two or more. Moreover, what mixed suitably polymer components other than a cellulose acylate may be used. 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 further preferably 92% or more. The cellulose acylate is preferably pelletized, and the preferred pellet size is 1 mm ^{3 to} 10 cm ³ , more preferably 5 mm ³ to 5 cm ³ , and even more preferably 10 mm ^{3 to 3} cm ³ . Then, it dries on the above-mentioned conditions. The obtained cellulose acylate is preferably stored in a low-temperature and dark place so that the storage is less affected by the environment. Furthermore, 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.

  As for a specific synthesis method of cellulose acylate, Synthesis Examples 1 and 2 described later can be referred to.

"Additive"
In the present invention, the following additives may be added to cellulose acylate.
(Plasticizer)
Examples of the plasticizer include alkylphthalylalkyl glycolates, phosphate esters and carboxylic acid esters, polyhydric alcohol plasticizers, and the like.
Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ester Le glycolate, and the like.

  Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Furthermore, it is preferable to use the phosphate ester plasticizer described in claims 3 to 7 of JP-T-6-501040. As described above, phosphate ester has an effect of promoting crystallization of cellulose acylate and generating streaks, but this effect is suppressed when used in combination with the present low molecular weight compound. For this reason, it is also possible to use together this low molecular weight compound and phosphate ester.

  Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diethyl hexyl phthalate; and citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate. And adipic acid esters such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, and bis (butyl diglycol adipate). In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.

The polyhydric alcohol plasticizer has good compatibility with cellulose acylate, and glycerin ester compounds such as glycerin ester and diglycerin ester, in which a thermoplastic effect is remarkably exhibited, and polyglycerin such as polyethylene glycol and polypropylene glycol. Examples include compounds in which an acyl group is bonded to the hydroxyl group of alkylene glycol or polyalkylene glycol.
Specific glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate myristate, glycerin diacetate laurate, glycerin diacetate caprate, glycerin diacetate nonanate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerol diacetate hexanoate, glycerol diacetate pentanoate, glycerol diacetate oleate, glycerol acetate dicaprate, glycerol acetate dioctanoate, glycerol acetate dioctanoate, glycerol acetate diheptanoate , Glycerol acetate dicaproate, glycerol acetate divalerate, glycerol acetate dibu Glycerol dipropionate caprate, glycerol dipropionate laurate, glycerol dipropionate myristate, glycerol dipropionate palmitate, glycerol dipropionate stearate, glycerol dipropionate oleate, glycerol tributyrate, glycerol tri Examples include but are not limited to pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and these are used alone or in combination. be able to.
Among them, glycerol diacetate caprylate, glycerol diacetate pelargonate, glycerol diacetate caprate, glycerol diacetate laurate, glycerol diacetate myristate, glycerol diacetate palmitate, glycerol diacetate stearate, glycerol diacetate oleate preferable.

Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglyceride. Glycerin tetracaprylate, diglycerin tetrapelargonate, diglycerin tetracaprate, diglycerin tetralaurate, diglycerin tetramyristate, diglycerin tetrapalmitate, diglycerin triacetate propionate, diglycerin triacetate butyrate, diglycerin Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate pelargonate, diglycerol triacetate caprate, diglycerol triacetate laurate, diglycerol triacetate myristate, diglycerol triacetate palmitate, diglycerol triacetate stearate, diglycerol triacetate oleate, diglycerol diacetate dipropionate, diglycerol Diacetate dibutyrate, diglycerin diacetate divalerate, diglycerin diacetate dihexanoate, diglycerin diacetate diheptanoate, diglycerin diacetate dicaprylate, diglycerin diacetate dipelargonate, diglycerin di Acetate dicaprate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglyceryl diacetate distearate, diglycerin diacetate dioleate, diglyceryl acetate tripropionate, diglyceryl acetate tributyrate, diglyceryl acetate trivalerate, diglyceryl acetate tri Hexanoate, diglycerol acetate triheptanoate, diglycerol acetate tricaprylate, diglycerol acetate tripelargonate, diglycerol acetate tricaprate, diglycerol acetate trilaurate, diglycerol acetate trimyristate, diglycerol acetate tri Palmitate, Diglycerol acetate tristearate, Diglycerol acetate trioleate, Diglycerol laurate, Jig Examples include, but are not limited to, mixed acid esters of diglycerin such as glycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin oleate, and these can be used alone or in combination.
Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferable.

  Specific examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1000, but are not limited thereto, and these can be used alone or in combination.

Specific examples of the compound in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristate, polyoxy Examples thereof include propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, but are not limited thereto, and these can be used alone or in combination.
These plasticizers are preferably 0 to 20% by mass, more preferably 1 to 20% by mass, and further preferably 2 to 15% by mass with respect to the cellulose acylate film. These plasticizers may be used in combination of two or more if necessary.

(Matting agent)
It is preferable to add fine particles as a matting agent to the cellulose acylate in the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate. Fine particles containing silicon are preferable because they can reduce turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary or secondary particle size, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

As the silicon dioxide 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. . The fine particles of zirconium oxide are commercially available, for example, under the trade names Aerosil R976 and R811 (above, manufactured by Nippon Aerosil Co., Ltd.), and these can be used.
Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

(UV absorber)
Next, the cellulose acylate in the present invention preferably contains an ultraviolet ray inhibitor and may contain one or more ultraviolet absorbers. From the viewpoint of preventing the deterioration of the liquid crystal, the ultraviolet absorber is preferably excellent in the ability to absorb ultraviolet rays having a wavelength of 380 nm or less, and less visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferable ultraviolet absorbers are benzotriazole compounds and benzophenone compounds, and among them, benzotriazole compounds are preferable because they have less unnecessary coloring with respect to cellulose acylate.

  Specific examples of preferable UV inhibitors include 2,6-di-tert-butyl-p-cresol and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. Triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl- 4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2,2- Thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- ( , 5-Di-tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl- 2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, etc. It is done.

  Furthermore, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy) -3′-tert-butyl-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2 ′ -Hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3- Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenol) ) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-tert-butyl-4 -Hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole- As a mixture of 2-yl) phenyl] propionate, and a UV absorber, a polymer UV absorber and a polymer type UV absorber described in JP-A-6-148430 are preferably used.

  In addition, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-tert A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 3.0%, more preferably 10 ppm to 2% in terms of mass ratio with respect to cellulose acylate.

These ultraviolet absorbers are available as the following commercial products.
The benzotriazole series includes TINUBIN P (manufactured by Ciba Specialty Chemicals Co., Ltd.), TINUBIN 234 (manufactured by Ciba Specialty Chemicals Co., Ltd.), TINUBIN 320 (manufactured by Ciba Specialty Chemicals Co., Ltd.), TINUBIN 326 ( Ciba Specialty Chemicals Co., Ltd.), TINUBIN 327 (Ciba Specialty Chemicals Co., Ltd.), TINUBIN 328 (Ciba Specialty Chemicals Co., Ltd.), Sumisorb 340 (Sumitomo Chemical Co., Ltd.), etc. There is. Further, 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 (Sipro Kasei Co., Ltd.) )), Seasorb 103 (manufactured by Sipro Kasei Co., Ltd.), Adekas Type LA-51 (manufactured by Asahi Denka Co., Ltd.), Chemisorp 111 (manufactured by Chemipro Kasei Co., Ltd.), UVINUL D-49 (manufactured by BASF), etc. Can be mentioned. Examples of the oxalic acid anilide ultraviolet absorber include TINUBIN 312 (manufactured by Ciba Specialty Chemicals) and TINUBIN 315 (manufactured by Ciba Specialty Chemicals). Moreover, as a salicylic acid type ultraviolet absorber, Seasorb 201 (manufactured by Sipro Kasei Co., Ltd.) and Seasorb 202 (manufactured by Sipro Kasei Co., Ltd.) are marketed, and as a cyanoacrylate ultraviolet absorber, Seasorb 501 (Sipro Kasei ( And UVINUL N-539 (manufactured by BASF).
As the ultraviolet absorber, for example, those described in JP-A-2001-151901 can be used in addition to the above. It is preferable to contain 0.001-5 mass% of ultraviolet absorbers with respect to cellulose acylate.

(Stabilizer)
In the present invention, as long as it does not impair the performance required as necessary, as a stabilizer for preventing thermal deterioration and coloring, phosphite compounds, phosphite compounds, phosphates, thiophosphates, You may add weak organic acid, an epoxy compound, etc. individually or in mixture of 2 or more types. As specific examples of the phosphite stabilizer, compounds described in paragraphs [0023] to [0039] of JP-A No. 2004-182979 can be more preferably used. Specific examples of the phosphite ester stabilizer include JP-A No. 51-70316, JP-A No. 10-306175, JP-A No. 57-78431, JP-A No. 54-157159, and JP-A No. 54-157159. The compounds described in JP-A-55-13765 can be used.

The addition amount of the stabilizer in the present invention is preferably 0.005 to 0.5 mass%, more preferably 0.01 to 0.4 mass%, and still more preferably 0.005 to 0.5 mass% with respect to cellulose acylate. It is 05-0.3 mass%. When the addition amount is less than 0.005% by mass, the effect of preventing deterioration and suppressing coloring during melt film formation is insufficient, which is not preferable. On the other hand, in the case of 0.5% by mass or more, it is not preferable because it oozes out on the surface of the melt-formed cellulose acylate film.
It is also preferable to add a deterioration inhibitor and an antioxidant. By adding a phenol compound, a thioether compound, a phosphorus compound or the like as a deterioration inhibitor or an antioxidant, a synergistic effect appears in deterioration and oxidation prevention. Furthermore, as other stabilizers, the materials described in detail on pages 17 to 22 of the Japan Institute of Invention Disclosure Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used. Can do.

(Other additives)
In addition to the above, various additives such as infrared absorbers, optical adjusting agents, surfactants, and odor trapping agents (such as amines) can be added. For these details, the materials described in detail on pages 17 to 22 of the invention association disclosure technique (public technical number 2001-1745, published on March 15, 2001, invention association) are preferably used.
As the infrared absorbing dye, for example, those described in JP-A No. 2001-194522 can be used. The infrared absorbing dye is preferably contained in an amount of 0.001 to 5 mass% with respect to the cellulose acylate.

  As the optical adjusting agent, for example, those described in JP-A No. 2001-166144, JP-A No. 2003-344655, JP-A No. 2003-248117, and JP-A No. 2003-66230 can be used. Thereby, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount of the optical adjusting agent is 0 to 15% by mass, more preferably 0 to 12% by mass, and further preferably 0 to 10% by mass.

<Melting film formation of cellulose acylate>
1) Pelletization The cellulose acylate and the additive are preferably mixed and pelletized prior to melt film formation.
The cellulose acylate and additives are preferably dried in advance for pelletization, but this can be substituted by using a vented extruder. In the case of drying, a method of heating at 90 ° C. for 8 hours or more in a heating furnace can be used as a drying method, but this is not restrictive. Pelletization can be made by melting the cellulose acylate and additives at 150 ° C. to 250 ° C. using a twin-screw kneading extruder, and then extruding them into noodles to solidify and cut in water. Alternatively, pelletization may be performed by an underwater cutting method or the like that is cut while directly extruding into water after melting by an extruder.
Any known single-screw extruder, non-meshing counter-rotating twin-screw extruder, meshing-type counter-rotating twin-screw extruder, meshing-type co-direction as long as the extruder is sufficiently melt kneaded A rotary twin screw extruder or the like can be used.

The preferred size is the cross-sectional area of 1 mm ² to 300 mm ² of the pellets, is 1mm~30mm is Preferably length, more preferably the cross-sectional area of 2 mm ² 100 mm ^2, the length is 1.5Mm～10mm.

  Moreover, when pelletizing, the said additive can also be injected | thrown-in from the raw material input port and vent port in the middle of an extruder.

  The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm, and even more preferably 30 rpm to 500 rpm. Accordingly, when the rotational speed is slow, the residence time becomes long, which is not preferable because the molecular weight is lowered due to thermal deterioration or the yellowishness is easily deteriorated. On the other hand, if the rotational speed is too high, molecules are likely to be cut by shearing, which leads to problems such as a decrease in molecular weight and an increase in the generation of cross-linked gel.

  The extrusion residence time in pelletization is 10 seconds to 60 minutes, more preferably 15 seconds to 30 minutes. If sufficient melting is possible, a shorter residence time is preferable in terms of suppressing resin deterioration and yellowing.

2) Drying In the method for producing a cellulose acylate film of the present invention, it is preferable to use a pellet formed by the above-mentioned method, and the moisture content in the pellet is 1% or less, more preferably 0.8% prior to melt film formation. After drying to 5% or less, more preferably to 0.01% or less, it is preferable to put into a hopper of a melt extruder. At this time, the temperature in the hopper is preferably 20 ° C to 110 ° C, more preferably 40 ° C to 100 ° C, and still more preferably 50 ° C to 90 °. At this time, the hopper is preferably maintained at a constant air volume and temperature with dehumidified air or the like, but this is not limited as long as the desired moisture content can be obtained. At this time, it is more preferable to enclose the inside of the hopper with a vacuum sealed structure and an inert gas such as nitrogen.

3) Melt Extrusion The cellulose acylate resin described above is melt extruded using a melt extruder 22 equipped with a screw as shown in FIG. That is, the cellulose acylate resin is supplied into the cylinder 32 through the supply port 40 of the hopper and is guided in the direction of the arrow by the screw 38. In the cylinder 32, in order from the supply port 40 side, a supply unit (region A) for quantitatively transporting the cellulose acylate resin supplied from the supply port, a compression unit (region B) for melt-kneading and compressing the cellulose acylate resin, and melt-kneading. -It is comprised with the measurement part (area | region C) which measures the compressed cellulose acylate resin. The resin is preferably dried in order to reduce the amount of water by the above-mentioned method. However, in order to prevent the molten resin from being oxidized by residual oxygen, the inside of the extruder is in an inert (nitrogen or the like) air flow or with a vent. More preferably, it is carried out while evacuating using an extruder. The screw compression ratio of the extruder is set to 2.5 to 4.5, and L / D is set to 20 to 70. Here, the screw compression ratio is the volume ratio between the supply unit (region A) and the metering unit (region C), that is, the volume per unit length of the supply unit (region A) ÷ the unit length of the metering unit (region C). The outer diameter d1 of the screw shaft of the supply unit (region A), the outer diameter d2 of the screw shaft of the metering unit (region C), the groove diameter a1 of the supply unit (region A), and the metering unit It is calculated using the groove part diameter a2 of (region C). L / D is the ratio of the cylinder length (L) to the cylinder inner diameter (D). Moreover, extrusion temperature is set to 190-240 degreeC. When the temperature in the extruder exceeds 230 ° C., the cooler 4 may be provided between the extruder and the die.

  If the screw compression ratio is less than 2.5 and is too small, it will not be sufficiently melt-kneaded and undissolved parts will occur, or the shear heat generation will be too small and the crystals will not melt sufficiently, resulting in a cellulose acylate film after production In this case, fine crystals are likely to remain, and bubbles are more likely to be mixed. As a result, the strength of the cellulose acylate film is reduced, or when the film is stretched, the remaining crystals inhibit the stretchability and the orientation cannot be sufficiently increased. On the other hand, if the screw compression ratio exceeds 4.5 and is too large, the shear stress is excessively applied and the resin is easily deteriorated due to heat generation, so that the cellulose acylate film after production is easily yellowed. On the other hand, when too much shear stress is applied, the molecules are cut and the molecular weight is lowered, so that the mechanical strength of the film is lowered. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably 2 in order to make the cellulose acylate film after production difficult to produce a yellowish color and have a high film strength and further make it difficult to stretch and break. .8 to 4.2, particularly preferably in the range of 3.0 to 4.0.

  On the other hand, if L / D is less than 20 and is too small, melting and kneading are insufficient, and fine crystals are likely to remain in the cellulose acylate film after production as in the case where the compression ratio is small. On the other hand, if L / D exceeds 70 and is too large, the residence time of the cellulose acylate resin in the extruder becomes too long, and the resin tends to be deteriorated. In addition, when the residence time is long, the molecules are cut or the molecular weight is lowered, so that the mechanical strength of the cellulose acylate film is lowered. Therefore, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 65, in order to make the cellulose acylate film after production hardly yellow, and the film strength is strong and further hardly breaks. Especially preferably, it is the range of 24-50.

  On the other hand, if the extrusion temperature is too low below 190 ° C., the crystals are not sufficiently melted, and fine crystals are likely to remain in the cellulose acylate film after production, and the film strength is reduced or the film is stretched. In this case, the remaining crystal hinders stretchability and the orientation cannot be sufficiently increased. On the other hand, when the extrusion temperature exceeds 240 ° C. and is too high, the cellose acylate resin is deteriorated and the yellowness (YI value) is deteriorated. Accordingly, the extrusion temperature is preferably 190 to 240 ° C., more preferably 195 to 235 ° C., and particularly preferably 200, in order to make the cellulose acylate film after production hardly yellowish and have high film strength and are difficult to stretch and break. It is in the range of ~ 230 ° C.

  The cellulose acylate film formed using an extruder having an extrusion temperature set as described above has characteristic values such that the haze is 2.0% or less and the yellow index (YI value) is 10 or less. .

Here, haze is an index indicating whether the extrusion temperature is too low, in other words, an index for knowing the amount of crystals remaining in the cellulose acylate film after production. If haze exceeds 2.0%, cellulose after production is obtained. Decrease in strength of the acylate film and breakage during stretching are likely to occur. The yellow index (YI value) is an index for knowing whether the extrusion temperature is too high. If the yellow index (YI value) is 10 or less, there is no problem in terms of yellowness.
In general, single-screw extruders with relatively low equipment costs are often used as the types of extruders, and there are screw types such as full flight, madok, and dalmage, but cellulose acid with relatively poor thermal stability. The rate resin is preferably a full flight type. In addition, although the equipment cost is expensive, it is possible to use a twin-screw extruder that can be extruded while devolatilizing unnecessary volatile components by providing a vent port in the middle by changing the screw segment. There are two types of shaft extruders, the same direction and the different direction, which can be used. However, the type of the same direction rotation with high self-cleaning performance is preferred because a stagnant portion is hardly generated. Although the twin-screw extruder is expensive, it has high kneadability and high resin supply performance, so that it can be extruded at a low temperature. For this reason, it is suitable for film formation of cellulose acetate resin. Moreover, it is also possible to use the cellulose acylate pellet and powder in an undried state as they are by appropriately arranging the vent port. Furthermore, film smears produced during film formation can be reused as they are without drying.

  In addition, although the diameter of a preferable screw changes with target extrusion rates per unit time, it is 10 mm-300 mm, More preferably, it is 20 mm-250 mm, More preferably, it is 30 mm-150 mm.

  In order to improve the thickness accuracy, it is important to reduce the fluctuation of the discharge amount. A gear pump is provided between the extruder and the die, and a certain amount of cellulose acylate resin is supplied from the gear pump. Is effective. A gear pump is accommodated in a state where a pair of gears composed of a drive gear and a driven gear are engaged with each other, and the drive gear is driven to engage and rotate the two gears, so that a melted state is generated from the suction port formed in the housing. Resin is sucked into the cavity, and a certain amount of the resin is discharged from a discharge port formed in the housing. Even if there is a slight fluctuation in the resin pressure at the front end of the extruder, the fluctuation is absorbed by using a gear pump, the fluctuation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness fluctuation is improved. By using a gear pump, it is possible to keep the fluctuation range of the resin pressure in the die portion 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 can also be used. In addition, a high-precision gear pump using three or more gears that eliminates gear fluctuations of the gear pump is also effective.

Other advantages of using a gear pump are that the pressure at the screw tip can be reduced to form a film, reducing energy consumption, preventing rise in resin temperature, improving transport efficiency, reducing residence time in the extruder, L / D can be expected to be shortened. In addition, when using a filter to remove foreign matter, if there is no gear pump, the amount of resin supplied from the screw may fluctuate as the filtration pressure increases. It can be resolved. On the other hand, the disadvantages of gear pumps are that the length of the equipment becomes longer depending on the equipment selection method, the residence time of the resin becomes longer, and the shearing stress of the gear pump section may cause the molecular chain to break. is required.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and even more preferably 4 minutes to 30 minutes. is there.

  Since the flow of the polymer for bearing circulation of the gear pump becomes worse, the polymer seal in the drive part and the bearing part becomes worse, and there is a problem that the fluctuation of the metering and liquid feeding pressure increases. A gear pump design (especially clearance) that matches the melt viscosity of the resin is required. In some cases, the staying part of the gear pump causes deterioration of the cellulose acylate resin, so that a structure with as little staying as possible is preferable. The polymer pipes and adapters that connect the extruder and gear pump or gear pump and die must also have a design with as little stagnation as possible, and to stabilize the extrusion pressure of cellulose acylate resin with high melt viscosity temperature dependence. It is preferable to make the temperature fluctuation as small as possible. Generally, a band heater having a low equipment cost is often used for heating the polymer tube, but it is more preferable to use an aluminum cast heater with less temperature fluctuation. Further, as described above, in order to give G ′, G ″, tan δ, and η maximum and minimum values in the extruder, it is preferable to heat and melt the extruder barrel with a heater divided into 3 to 20.

  The cellulose acylate resin is melted by the extruder configured as described above, and the molten resin is continuously fed from the discharge port to the die. As long as the die is designed so that the molten resin stays in the die, any type of commonly used T die, fishtail die, and hanger coat die may be used. Also, there is no problem in placing a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance at the T-die exit portion is generally 1.0 to 5.0 times the film thickness, preferably 1.2 to 3 times, and more preferably 1.3 to 2 times. When the lip clearance is 1.0 times smaller than the film thickness, it is difficult to obtain a good sheet by film formation. Further, when the lip clearance is larger than 5.0 times the film thickness, the sheet thickness accuracy is lowered, which is not preferable. The die is a very important facility for determining the thickness accuracy of the film, and a die that can control the thickness adjustment severely is preferable. Normally, the thickness can be adjusted at intervals of 40 to 50 mm, but preferably a type capable of adjusting the film thickness at intervals of 35 mm or less, more preferably at intervals of 25 mm or less. In addition, since the cellulose acylate resin is highly dependent on the temperature and the shear rate of the melt viscosity, it is important to design the temperature unevenness of the die and the flow speed unevenness in the width direction as much as possible. An automatic thickness adjustment die that measures the downstream film thickness, calculates the thickness deviation, and feeds back the result to the die thickness adjustment is also effective in reducing the thickness fluctuation in long-term continuous production.

  For production of a film, a single-layer film forming apparatus with a low equipment cost is generally used. However, in some cases, a film having two or more types of structures can also be manufactured using a multilayer film forming apparatus in order to provide a functional layer on an outer layer. Is possible. In general, the functional layer is preferably thinly laminated on the surface layer, but the layer ratio is not particularly limited.

  In order to filter foreign matter in the resin and avoid damage to the gear pump due to foreign matter, it is preferable to perform so-called breaker plate type filtration in which a filter medium is provided at the outlet of the extruder. In order to filter foreign matter with higher accuracy, it is preferable to provide a filtration device incorporating a so-called leaf type disk filter after passing through the gear pump. Filtration can be performed by providing one filtration section, or multistage filtration performed by providing a plurality of places. The filtration accuracy of the filter medium is preferably higher, but the filtration accuracy is preferably 15 μm to 3 μm, more preferably 10 μm to 3 μm from the viewpoint of the pressure resistance of the filter medium and the increase in the filtration pressure due to clogging of the filter medium. In particular, when using a leaf-type disk filter device that finally filters foreign matter, it is preferable to use a filter medium with high filtration accuracy in terms of quality, and it is adjusted by the number of loaded sheets to ensure the suitability of pressure resistance and filter life. Is possible. The type of filter medium is preferably a steel material because it is used under high temperature and high pressure. Among steel materials, stainless steel, steel, etc. are particularly preferable, and stainless steel is particularly preferable in terms of corrosion. . As a configuration of the filter medium, for example, a sintered filter medium formed by sintering metal long fibers or metal powder can be used in addition to a knitted wire, and a sintered filter medium is preferable in terms of filtration accuracy and filter life.

4) Casting By the above method, the molten resin extruded into a sheet form from the die can be cooled and solidified on a casting drum to obtain a cellulose acylate film. At this time, it is preferable to increase the adhesion between the casting drum and the melt-extruded sheet by using an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, a touch roll method or the like. Such an adhesion improving process may be performed on the entire surface of the melt-extruded sheet or a part thereof. In particular, a method called “edge pinning”, in which only both ends of the film are brought into close contact with each other, is often used, but the method is not limited to this.

  The method for producing a cellulose acylate film of the present invention is characterized in that a multiple casting drum having a plurality of casting drums is used as a casting drum for melt film formation. The number of casting drums included in the multiple casting drum is preferably 2 to 6, more preferably 3 to 5, and further preferably 3 to 4. As a specific example of the multiple casting drum used in the present invention, a multiple casting drum 14 having three casting drums as shown in FIG. 2 can be exemplified. The three casting drums are a first casting drum 26, a second casting drum 28, and a third casting drum 30 from the die 24 side. The diameters r1, r2, and r3 of each drum constituting the multiple casting drum are preferably 50 mm to 5000 mm, more preferably 100 mm to 2000 mm, and still more preferably 150 mm to 1000 mm. Further, the intervals s1 and s2 between the plurality of rolls are preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm between the faces.

The surface temperature of the multiple casting drum of the present invention is preferably gradually cooled. In the method for producing a cellulose acylate film of the present invention, the surface temperature of the first casting drum 26 in which the cellulose acylate extruded from the die 24 is first melt cast is (Tg-30) ° C. to (Tg + 15) ° C. More preferably, it is (Tg-30) ° C to (Tg + 10) ° C, and more preferably (Tg-25) ° C to (Tg + 10) ° C. Here, “Tg” means the glass transition temperature (Tg) of cellulose acylate when melt cast. Since Tg is lowered by additives such as ultraviolet absorbers, stabilizers, and plasticizers added to cellulose acylate, Tg is determined by the composition at the time of melt casting.
The first casting drum has a temperature difference between both ends of the roll surface of 10 ° C. or less, preferably 8 ° C. or less, and more preferably 5 ° C. or less. Furthermore, the surface temperature of the second casting drum 28 is preferably 1 ° C. to 20 ° C. lower than the first casting drum 26, more preferably 2 ° C. to 20 ° C., and further 5 ° C. to 20 ° C. preferable. Furthermore, the surface temperature of the third casting drum 30 is preferably 1 ° C to 30 ° C lower than the second casting drum 28, more preferably 2 ° C to 30 ° C lower, and 5 ° C to 30 ° C lower. Further preferred.

  In this way, by setting the number of multiple casting drums and the temperature distribution of the drums, the both surfaces of the film are brought into contact with a mirror-like metal drum, whereby the surface properties and physical properties of the cellulose acylate film of the present invention obtained are obtained. Can be made uniform. In addition, by bringing both surfaces of the film into contact with a mirror-like metal drum, the amount of the additive contained in the surface layer and the surface layer on both surfaces is made uniform. The difference is reduced, and the difference in adhesiveness with the polarizing film can be eliminated by using either surface.

  Furthermore, by setting the surface temperature of the multiple casting drum at around Tg as described above, the crystallinity of the cellulose acylate is increased, the improvement of the packing density is promoted, and the resulting cellulose acylate is obtained. When the water permeability of the film is reduced and used as a protective film for a polarizing plate, durability at high temperature and high humidity can be improved.

Thereafter, the film-like cellulose acylate 12 is peeled off from the casting drum, passed through the nip rolls 31A and 31B, and wound up. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.
The film-forming width of the cellulose acylate film of the present invention is preferably 0.7 m to 5 m, more preferably 1 m to 4 m, and further preferably 1.3 m to 3 m.

  When the so-called touch roll method is used, the surface of the touch roll may be a resin such as rubber or Teflon (registered trademark) 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.

In the present invention, it is more preferable to form a film using a touch roll on a casting drum after extrusion from a die after melting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll to be cooled and solidified. Such a touch roll preferably has elasticity in order to reduce residual strain generated when the melt from the die is sandwiched between the rolls. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably It is 0.2 mm-5.0 mm, More preferably, it is 0.3 mm-2.0 mm or less. For example, by reducing the thickness of the outer cylinder, an elastic body layer is provided on a metal shaft or an elastic body layer, and the outer cylinder is placed on the elastic body layer, and a liquid medium layer is provided between the elastic body layer and the outer cylinder. The thing which enabled the touch roll film formation by the ultra-thin outer cylinder by satisfy | filling is mentioned. The casting roll and the touch roll preferably have a mirror surface, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Specifically, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, JP-A-2004-216717, JP-A-2003-145609, and International Publication No. 97/28950. Those listed in the pamphlet can be used.
Thus, since the touch roll is filled with the fluid inside the thin outer cylinder, when the touch roll is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Therefore, since the touch roll and the casting roll are in surface contact with the cooling roll, the pressure is dispersed and a low surface pressure can be achieved. For this reason, the fine unevenness | corrugation of the surface can be corrected, without leaving a residual distortion in the film pinched | interposed between these. The linear pressure of the preferred touch roll is 3 kg / cm to 100 kg / cm, more preferably 5 kg / cm to 80 kg / cm, and still more preferably 7 kg / cm to 60 kg / cm. The linear pressure referred to here is a value obtained by dividing the force applied to the touch roll by the width of the discharge port of the die. By adjusting the linear pressure in this way, both sides of the film are uniformly sandwiched, so that the plane orientation of the film can be promoted, the water permeability can be reduced, and the durability of the polarizing plate can be further improved. Further, since the surface pressure is uniformly applied to both surfaces of the film, the physical properties of both surfaces of the film can be made more uniform. Furthermore, the effect which reduces the fine unevenness | corrugation (die line) and thickness unevenness which were formed in the film further is acquired.

  The touch roll temperature is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and further preferably 75 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls.

5) Winding The sheet thus obtained is preferably trimmed at both ends and wound. The trimmed portion is re-processed as a raw material for the same type of film or as a raw material for a film of a different type after being pulverized or subjected to processing such as granulation or depolymerization / repolymerization as necessary. May be used. As the trimming cutter, any type of rotary cutter, shear blade, knife, or the like may be used. As for the material, either carbon steel or stainless steel may be used. In general, it is preferable to use a cemented carbide blade or a ceramic blade because the life of the blade is long and the generation of chips is suppressed.

  Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding. A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 2 kg / m width to 40 kg / width, and still more preferably 3 kg / m width to 20 kg / width. When the winding tension is smaller than 1 kg / m width, it is difficult to wind the film uniformly. On the other hand, when the winding tension exceeds 50 kg / width, the film becomes tightly wound, not only the appearance of the winding is deteriorated, but also the bump portion of the film extends due to the creep phenomenon, and the film wave This is not preferable because it causes a cause or residual birefringence due to the elongation of the film. The winding tension is preferably detected by tension control in the middle of the line and is wound while being controlled to have a constant winding tension. If there is a difference in film temperature depending on the location of the film production line, the length of the film may be slightly different due to thermal expansion. It is necessary to prevent tension.

  The winding tension can be wound at a constant tension by controlling the tension control. However, it is more preferable that the winding tension is tapered to an appropriate winding tension according to the wound diameter. Generally, the tension is gradually reduced as the winding diameter increases, but in some cases, it may be preferable to increase the tension as the winding diameter increases.

≪Physical properties of unstretched cellulose acylate film≫
The unstretched cellulose acylate film thus obtained preferably has an in-plane retardation (Re) of 0 ≦ Re ≦ 20 nm and a thickness direction retardation (Rth) of 0 ≦ Rth ≦ 60 nm. More preferably, Re = 0 to 15 nm and Rth = 0 to 55 nm, and further preferably Re = 0 to 10 nm and Rth = 0 to 50 nm.
Re and Rth respectively represent in-plane retardation and retardation in the thickness direction. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) by making light incident in the normal direction of the film. Rth is Re, the slow axis in the plane (determined by KOBRA-21ADH) is used as the tilt axis (rotation axis), and the angle is changed with respect to the normal direction of the film. KOBRA-21ADH is calculated based on the plurality of retardation values measured. In this specification, 590 ± 5 nm is used as λ unless otherwise specified.
The total light transmittance of the unstretched cellulose acylate film thus obtained is preferably 90% to 100%, more preferably 91 to 100%, and further preferably 92 to 100%. The preferred haze is 0 to 1%, more preferably 0 to 0.8%, still more preferably 0 to 0.6%.
The thickness of the unstretched cellulose acylate film is preferably 30 μm to 250 μm, more preferably 35 μm to 200 μm, and still more preferably 40 μm to 200 μm. The thickness unevenness is preferably 0% to 3% in both the longitudinal direction and the width direction, more preferably 0% to 2%, and still more preferably 0% to 1%.
Preferably, the modulus in tension is ^{1.5kN / mm 2 ~3.5kN / mm 2} , more preferably ^{1.7kN / mm 2 ~2.8kN / mm 2} , more preferably 1.8kN / mm ² ~2.6kN / Mm ² .
The breaking elongation at normal temperature is preferably 3% to 200%, more preferably 5% to 200% or less, and still more preferably 8% to 180%.
Tg (Tg of a film, that is, Tg of a mixture of cellulose acylate and additive) is preferably 95 ° C to 145 ° C, more preferably 100 ° C to 140 ° C, and further preferably 105 ° C to 135 ° C.
The thermal dimensional change at 80 ° C./day is preferably 0% to ± 0.5% or less in both the vertical and horizontal directions, more preferably 0% to ± 0.3%, still more preferably 0% to ± 0.2%. % Or less.
Furthermore, the equilibrium water content at 25 ° C. and relative humidity 80% is preferably 1% by mass to 4% by mass, more preferably 1.2% by mass to 3% by mass, and even more preferably 1.5% by mass to 2.5% by mass. % By mass.

<Extension>
An unstretched cellulose acylate film formed by the above method may be stretched. Thereby, Re and Rth can be controlled.
The stretching is preferably performed at Tg to (Tg + 50) ° C, more preferably (Tg + 3) ° C to (Tg + 30) ° C, and further preferably (Tg + 5) ° C to (Tg + 20) ° C. A preferable draw ratio is 1% to 250%, more preferably 2% to 200%, and further preferably 3% to 150% on at least one side. Although it may be stretched evenly in the vertical and horizontal directions, it is more preferable to stretch one of the stretch ratios more than the other and stretch the same. Either length (MD) or width (TD) may be increased, but the smaller draw ratio is preferably 0% to 30%, more preferably 0% to 25%, and still more preferably 0% to 20%. %. The larger draw ratio is 1% to 250%, more preferably 10% to 200%, and still more preferably 30% 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 may be performed in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side (longitudinal stretching), and both ends of the film are gripped by chucks and are orthogonally crossed (longitudinal direction). (Perpendicular direction). Moreover, you may use the simultaneous biaxial stretching method of Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.
The ratio of Re and Rth can be freely controlled by controlling the value (aspect ratio) obtained by dividing the space between nip rolls by the film width in the case of longitudinal stretching. That is, the Rth / Re ratio can be increased by reducing the aspect ratio. Also, Re and Rth can be controlled by combining longitudinal stretching and lateral stretching. That is, Re can be reduced by reducing the difference between the longitudinal draw ratio and the transverse draw ratio, and Re can be increased by increasing this difference.

It is preferable that Re and Rth of the cellulose acylate film thus stretched satisfy the following formula.
Rth ≧ Re
300 ≧ Re ≧ 0
500 ≧ Rth ≧ 30

More preferably, as Re and Rth,
Rth ≧ Re × 1.1
250 ≧ Re ≧ 10
400 ≧ Rth ≧ 50
And
More preferably,
Rth ≧ Re × 1.2
200 ≧ Re ≧ 20
350 ≧ Rth ≧ 80
It is.

  The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, it is preferably as close to 0 °, preferably 0 ± 3 °, more preferably 0 ± 2 °, and further preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is more preferable.

The physical properties of the stretched cellulose acylate film are preferably in the following ranges.
The thickness of the stretched cellulose acylate film is preferably 15 μm to 200 μm, more preferably 30 μm to 170 μm, and still more preferably 40 μm to 140 μm. The thickness unevenness is preferably 0% to 3% in both the longitudinal direction and the width direction, more preferably 0% to 2%, and still more preferably 0% to 1%.
Preferably, the modulus in tension is ^{1.5kN / mm 2 ~3.5kN / mm 2} , more preferably ^{1.7kN / mm 2 ~2.8kN / mm 2} , more preferably 1.8kN / mm ² ~2.6kN / Mm ² .
The breaking elongation at normal temperature is preferably 3% to 150%, more preferably 5% to 140%, and still more preferably 8% to 140%.
The thermal dimensional change at 80 ° C./day is preferably 0% to ± 0.5% or less in both the vertical and horizontal directions, more preferably 0% to ± 0.3% or less, and still more preferably 0% to ± 0. 2% or less.
The equilibrium water content at 25 ° C. and 80% relative humidity is preferably 1% by mass to 4% by mass, more preferably 1.2% by mass to 3% by mass, and even more preferably 1.5% by mass to 2.5% by mass. It is.
The haze is 0% to 3%, more preferably 0% to 2%, and still more preferably 0% to 1%.
The total light transmittance is preferably 90% to 100%, more preferably 91% to 100%, and still more preferably 92% to 100%.

≪Processing application of cellulose acylate film≫
"surface treatment"
The unstretched and stretched cellulose acylate film of the present invention achieves 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. be able to. As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment, or alkali saponification 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, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. Can be mentioned. Details of these are described in pages 30 to 32 of the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). In the plasma treatment at atmospheric pressure, which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. Among these, the alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose acylate film. Specifically, JP-A Nos. 2003-3266, 2003-229299, 2004-322928, and 2005-76088 can be used.

(Saponification process)
In the alkali saponification treatment, the film may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method).

(Alkaline solution)
The cellulose acylate film of the present invention is preferably saponified using an alkaline solution having a concentration of 2 mol / L or more as a saponification solution. The saponification solution is composed of an alkali agent and water, and may optionally contain a surfactant and a compatibilizer.
The concentration of the alkali solution (content of the alkali agent in the alkali solution) needs to be determined according to the acyl substitution degree of the cellulose acylate. That is, in cellulose acylate, the saponification efficiency is significantly reduced as the carbon number of the acyl group increases, so the alkali concentration needs to be increased as the carbon number of the acyl group increases, but the alkali concentration is too high. The stability of the alkaline solution is impaired, and precipitation may occur during long-time application. Therefore, it is important to select an alkaline solution appropriately according to the primary structure of cellulose acylate. Therefore, the alkaline solution used in the present invention is preferably 2 mol / L or more, more preferably 2.5 to 15 mol / L, further preferably 2.5 to 10 mol / L. Most preferably, it is 5-8 mol / L. Moreover, the density | concentration of an alkaline solution can also be adjusted according to the kind of alkaline agent to be used, reaction temperature, and reaction time within this range.

  In this invention, when using the alkali saponification liquid (2-4 mol / L aqueous solution of sodium hydroxide and potassium hydroxide) normally used for a cellulose triacetate (TAC) film, saponification process temperature is 41 to 80 degreeC. It is preferably carried out at a temperature, more preferably 41 ° C. to 70 ° C., and more preferably 41 ° C. to 65 ° C. If the saponification temperature is 41 ° C. or higher, the saponification of the cellulose acylate surface is likely to proceed, the contact angle of water for hydrophilization is good, and the adhesiveness to the polarizing film is easily obtained. It becomes easy to manufacture the polarizing plate which has. On the other hand, if the saponification temperature is too high, components (such as plasticizer) in the acylate film may be extracted, or excessive swelling of the film may occur, causing problems such as whitening of the film surface. Sometimes.

Examples of other alkaline agents of the present invention include tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, ammonium carbonate, ammonium bicarbonate, sodium borate, potassium, ammonium And inorganic alkali agents such as sodium hydroxide, potassium, lithium and ammonium. In addition, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Ethyleneimine, ethylenediamine, pyridine, DBU (1,8-diazabicyclo [5,4,0] -7-undecene), DBN (1,5-diazabicyclo [4,3,0] -5-nonene), tetramethylammonium Hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylbutylammonium Organic alkali agents such as Dorokishido be used. These alkali agents can be used alone or in combination of two or more, and a part of them may be added in the form of a salt, for example, halogenated.
Among these alkali agents, sodium hydroxide and potassium hydroxide are preferable. The reason is that the pH can be adjusted in a wide pH range by adjusting these amounts.

  The solvent of the alkaline solution is a single solvent of water or a mixed solvent of water and an organic solvent. Preferred organic solvents include alcohols, alkanols, monoethers of glycol compounds, ketones, amides, sulfoxides, ethers, more preferably alcohols having a molecular weight of 61 or more, more preferably molecular weights. 61 or more glycols, specifically, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerol monomethyl ether, glycerol monoethyl ether, cyclohexanediol, cyclohexanedimethanol, diethylene glycol, dipropylene glycol, etc. Is mentioned. You may use the organic solvent used together with water individually or in mixture of 2 or more types.

When at least one organic solvent is used alone or in combination of two or more organic solvents, those having high solubility in water are preferable. The solubility of water in the organic solvent is preferably 50% by mass or more, and more preferably freely mixed with water. An alkali solution having sufficient solubility in an alkali agent, a salt of a fatty acid by-produced by a saponification treatment, a carbonate salt generated by absorbing carbon dioxide in the air, and the like can be prepared.
The use ratio of the organic solvent in the solvent is determined according to the type of solvent, miscibility with water (solubility), reaction temperature and reaction time. In order to complete the saponification reaction in a short time, it is preferable to prepare a solution at a high concentration. However, if the solvent concentration is too high, components (such as a plasticizer) in the acylate film may be extracted or excessive swelling of the film may occur, and it is necessary to select appropriately.
The mixing ratio of water and organic solvent is preferably 50/50 to 95/5 mass ratio. More preferably, it is 60 / 40-90 / 10 mass ratio, More preferably, it is 70 / 30-90 / 10 mass ratio. Within this range, the entire film surface is easily saponified uniformly without impairing the optical properties of the acylate film.

Like the alkaline solution preferably used in the present invention, the high-concentration alkaline solution absorbs CO ₂ in the environmental atmosphere and becomes carbonic acid in the solution, lowering the pH and easily generating carbonate precipitates. The CO ₂ concentration is preferably 5000 ppm or less. In order to suppress the absorption of CO _{2 in} the environmental atmosphere, it is more preferable that the coating coater of the alkaline solution has a semi-sealed structure or is covered with dry air, an inert gas, or an organic solvent saturated vapor of the alkaline solution.

(Surfactant)
The alkaline solution of the present invention can also contain a surfactant. By adding the surfactant, even if the organic solvent extracts the film-containing material, it is stably present in the alkaline solution, and the extracted material does not precipitate and solidify in the subsequent water washing step. The surfactant preferably used is described in, for example, JP-A No. 2003-313326.

(Defoamer)
The alkaline solution of the present invention can contain an antifoaming agent, and examples of the antifoaming agent preferably used are described in, for example, JP-A No. 2003-313326.

(Antidepressant / Antimicrobial agent)
The alkaline solution used in the present invention may contain an antifungal agent and / or an antibacterial agent, and the antifungal agent / antifungal agent preferably used is described in, for example, JP-A No. 2003-313326. is there.

(water)
In addition, as water used for the alkaline solution, the Japanese Waterworks Act (Act No. 177 of 1957) and the ministerial ordinance on water quality standards based on it (August 31, 1978 Ministry of Health and Welfare Ordinance No. 56), Based on Law No. 125 of July 10, 2011 and its separate table) and the influence on each element, mineral, etc. in the state of mixing in water prescribed by the WHO regulated tap water standard is preferable.
In order to more reliably achieve the effect of the present invention, it is preferable to use the water described above, and the calcium concentration of the alkaline solution is preferably 0.001 to 400 mg / L, and 0.001 to 150 mg / L. Is more preferable, and 0.001 to 10 mg / L is particularly preferable. The magnesium concentration is preferably 0.001 to 400 mg / L, more preferably 0.001 to 150 mg / L, and particularly preferably 0.001 to 10 mg / L. It is preferable that other polyvalent metal ions other than calcium and magnesium are not included. The concentration of the polyvalent metal ion is preferably 0.002 to 1000 mg / L. On the other hand, it is preferable that the alkali solution does not contain anions such as chloride ions and carbonate ions. The chloride ion concentration is preferably 0.001 to 500 mg / L, more preferably 0.001 to 300 mg / L, and particularly preferably 0.001 to 100 mg / L. Moreover, it is preferable that carbonate ions are not included. The carbonate ion concentration is preferably 0.001 to 3500 mg / L, more preferably 0.001 to 1000 mg / L, and particularly preferably 0.001 to 200 mg / L. In these concentration ranges, generation of insoluble matter in the solution is suppressed.

(Alkaline saponification treatment)
As described above, the cellulose acylate film of the present invention is preferably subjected to the alkali saponification treatment by the step of saponifying the film with the alkali solution and the step of washing off the alkali solution from the film. Then, you may include the process of neutralizing an alkaline solution, and the process of washing off a neutralization liquid from a film. These steps are preferably carried out while transporting the film, and a method of immersing in an alkaline solution as described in JP-A-2001-188130 may be used, as described in JP-A-2004-203965. A method of applying an alkaline solution may be used.
The saponification time is preferably 1 to 10 minutes, preferably 2 to 8 minutes, and more preferably 2 to 6 minutes. If the saponification time is too long, the polarizing plate durability described later is adversely affected.
In the case of a saponification step immersed in an alkaline solution, the saponification solution is preferably convected in a saponification solution tank. The convection velocity can be measured from the amount of string drawn out per unit time by putting a float having the same specific gravity as the solution in which the string is attached to the solution, and the linear velocity is preferably 1 m / min or more. 10 to 1000 m / min, more preferably 30 to 500 m / min, and most preferably 50 to 300 m / min. Convection of the saponification solution can be carried out with stirring blades in the solution tank. In the saponification solution tank, the difference between the saponification solution temperature near the entrance where the film is immersed and the saponification solution temperature near the exit where the film is removed from the saponification solution is 0.1 ° C. or more. Is preferable, it is more preferable that it is 0.5-20 degreeC, and it is further more preferable that it is 3-10 degreeC. Further, it is most preferable that the temperature near the outlet is higher. Thereby, precipitation of the additive in a film can be suppressed and the contact angle of a film can be reduced efficiently. The temperature difference of the saponification solution can be set using a method such as providing a partition plate in the alkaline solution tank to prevent the solution flow and adding a heater for raising the temperature.

  In addition, the cellulose acylate film additive that has dissolved in the liquid adheres to the cellulose acylate film and causes bright spot failure (foreign substance defect), so activated carbon is used to adsorb and remove the eluted components. A method is available. Activated carbon only needs to have a function of removing colored components in the saponification solution, and there is no limitation on the form, material, and the like. It may be a method of putting activated carbon directly into an alkali saponification solution tank, or a method of circulating a saponification solution between a saponification solution tank and a purifier filled with activated carbon.

《Function layer addition》
Functions described in detail on pages 32 to 45 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society for Invention and Innovation) in the stretched and unstretched cellulose acylate films of the present invention It is preferable to combine the functional layers. Among these, application of a polarizing film (polarizing plate), application of an optical compensation layer (optical compensation film), application of an antireflection layer (antireflection film), and application of a hard coat layer are preferred.
It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the above surface treatment or may be coated without the surface treatment. These surface treatments and undercoating steps can be incorporated at the end of the film forming step, or can be performed alone.

(1) Production of polarizing film [Material used for polarizing film]
Currently, a polarizing film (layer) used for a commercially available polarizing plate is obtained by immersing a stretched polymer in a solution of iodine or a dichroic dye in a bath and allowing the binder or dichroic dye to penetrate into the binder. Generally, it is produced by this. Examples of the polarizing film include Optiva Inc. A coating type polarizing film typified by can also be used. Iodine and dichroic dye in the polarizing film exhibit polarizing performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compounds described in page 58 of the Japan Society of Invention Disclosure Technique (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society of Invention).

  The polarizing film is not particularly limited as long as it has a thickness of 35 μm or less, and various types can be used. Examples of the polarizing film include hydrophilic polymer films such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and iodine and dichroic dyes. Examples thereof include polyene-based oriented films such as those obtained by adsorbing chromatic substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizing film composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. Particularly, the dyeability of a polyvinyl alcohol film dyed with iodine is favorable and suitable.

  A polarizing film having a thickness of 30 μm or less can be formed, for example, by dyeing, crosslinking, stretching, and drying a polyvinyl alcohol film having a thickness of 100 μm or less with iodine.

  As the polyvinyl alcohol-based film, a film formed by any method such as a casting method, a casting method, an extrusion method, etc., in which a stock solution in which a polyvinyl alcohol-based resin is dissolved in water or an organic solvent is cast is used. can do. 100-5000 are preferable and, as for the polymerization degree of a polyvinyl alcohol-type resin, 1400-4000 are more preferable. The film thickness of the polyvinyl alcohol film is preferably 100 μm or less, more preferably 20 to 90 μm, and still more preferably 20 to 85 μm. When the film thickness of the polyvinyl alcohol film exceeds 100 μm, the color change of the display panel becomes large when mounted on a liquid crystal display device or the like. On the other hand, when the film thickness is too thin, stretching becomes difficult.

  In the dyeing process, the polyvinyl alcohol film is immersed in a dyeing bath at 20 to 70 ° C. to which iodine is added for 1 to 20 minutes to adsorb iodine. The iodine concentration in the dyeing bath is usually 0.1 to 1 part by mass per 100 parts by mass of water. In the dye bath, in order to increase dyeing efficiency, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, iodine An auxiliary such as iodide such as tin iodide and titanium iodide may be added in an amount of 0.02 to 20 parts by mass, preferably 2 to 10 parts by mass. The dyeing bath may contain a small amount of an organic solvent compatible with water in addition to the water solvent. The polyvinyl alcohol film may be subjected to a swelling treatment at 20 to 60 ° C. for 0.1 to 10 minutes in a water bath or the like before being dyed in an aqueous solution containing iodine or a dichroic dye.

  In the crosslinking step, the dyed polyvinyl alcohol film is stretched in a boron compound-containing aqueous solution. The boron compound-containing aqueous solution usually contains 1 to 10 parts by mass of a polyvinyl alcohol crosslinking agent such as boric acid, borax, glyoxal, and glutaraldehyde alone or mixed with 100 parts by mass of water. In aqueous solution containing boron compound, in order to obtain in-plane uniform characteristics, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, steel iodide, barium iodide Auxiliary agents such as iodides such as calcium iodide, tin iodide and titanium iodide may be added in an amount of 0.05 to 15% by mass, preferably 0.5 to 8% by mass. The temperature of the boron compound-containing aqueous solution is usually 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time is not particularly limited, but is usually 1 second to 15 minutes, preferably 5 seconds to 10 minutes. The boron compound-containing aqueous solution may contain a small amount of an organic solvent compatible with water in addition to the aqueous solvent.

  In the drying step, the polyvinyl alcohol film subjected to the iodine adsorption alignment treatment is further added to an aqueous iodide solution such as potassium iodide having a water temperature of 10 to 60 ° C., preferably 30 to 40 ° C. and a concentration of 0.1 to 10% by mass. After being immersed for 1 second to 1 minute, washed with water and dried at 20 to 80 ° C. for 1 minute to 10 minutes to obtain a polarizing film. In the iodide aqueous solution, auxiliary agents such as zinc sulfate and zinc chloride may be added.

In the case of the stretching method, the stretching ratio is preferably 3.0 to 20.0 times, more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 3.0 to 10.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 7.5 times. When the total draw ratio of the wet drawing is less than 3.0 times, it is difficult to obtain a polarizing plate having a high degree of polarization, and when it exceeds 7.5 times, the film tends to break. The stretching ratio here is (length of polarizing film after stretching) / (length of polarizing film before stretching).
The stretching direction may be performed parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching methods are not particularly limited with respect to the stretching method, the number of stretchings, and the like, and may be performed in each step of dyeing and crosslinking, or may be performed in any one step. Moreover, you may perform several times in the same process.

(I) Parallel Stretching Method In the parallel stretching method, it is preferable to swell the PVA film prior to stretching. The degree of swelling is 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, it is preferably stretched at a bath temperature of 15 to 50 ° C., especially 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic material while being continuously conveyed through a guide roll or the like. . Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll.

(II) Diagonal Stretching Method In the oblique stretching method, a method of stretching using a tenter protruding in an oblique direction in an oblique direction described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The moisture content is preferably 5% to 100%, the stretching temperature is preferably 40 ° C to 90 ° C, and the humidity during stretching is preferably 50% to 100% in terms of relative humidity.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

  In addition, the moisture content of the polarizing film when bonded to the protective film (the water mass ratio in the polarizing film in the total mass of the polarizing film) is generally less than 20% by mass, although it depends on the thickness of the polarizing film, A range of 5 to 20% by mass, particularly 13 to 17% by mass is preferable. When the moisture content exceeds 20% by mass, the amount of moisture change after the production of the polarizing plate is increased, which adversely affects the decrease in polarization degree and durability at high temperature and high humidity.

[Lamination]
A stretched and unstretched cellulose acylate film after saponification and a polarizing film prepared by stretching are bonded to produce a polarizing plate. There are no particular restrictions on the direction of bonding, but it is preferable that the direction of the casting axis of the cellulose acylate film and the direction of the stretching axis of the polarizing plate be 0 °, 45 °, or 90 °.
The adhesive for bonding is not particularly limited, and examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.
Examples of the laminated layer structure include the following.
B) A / P / A
B) A / P / B
C) A / P / T
D) B / P / B
E) B / P / T
"A" is an unstretched cellulose acylate film of the present invention, "B" is a stretched cellulose acylate film of the present invention, "T" is a cellulose triacetate film (Fuji Photo Film Co., Ltd., Fujitac TD80U, etc.), “P” refers to a polarizing film.

In the case of the constitutions a) and b), A and B may be the same composition or different cellulose acetates. In the case of the structure d), B may be different in cellulose acetate having the same composition, or may be different in the same draw ratio. When the polarizing plate of the present invention is incorporated in a liquid crystal display device, either of them may be used as a liquid crystal surface, but in the case of configurations b) and e), it is more preferable that B is on the liquid crystal side.
When the polarizing plate of the present invention is incorporated in a liquid crystal display device, a substrate containing a liquid crystal is usually disposed between two polarizing plates. In this case, the polarizing plates of the present invention (i) to (e) and normal polarized light. Plates (T / P / T) can be freely combined. However, it is preferable to provide a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like on the film on the outermost surface of the display side of the liquid crystal display device.

The polarizing plate thus obtained preferably has a higher light transmittance and a higher degree of polarization. The transmittance of the polarizing plate of the present invention is preferably 42.0% or more, specifically, preferably 42% to 50%, more preferably 42.5% to 50%, and still more preferably. It is in the range of 43.0% to 50%, most preferably 43.5% to 50%. The degree of polarization is preferably 99.0% or more, specifically, preferably in the range of 99% to 100%, more preferably 99.5% to 100%, and still more preferably 99. It is in the range of 6% to 100%, most preferably 99.9% to 100%.
Furthermore, the polarizing plate of the present invention thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 °. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.
A protective film may be bonded to one surface of these polarizing plates, and a separate film may be bonded to the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.
Further, the decrease in the degree of polarization after being kept for 1000 hours in an environment of 80 ° C. and 90% relative humidity is preferably 1% or less, more preferably 0.8% or less, and 0.5% or less. It is particularly preferred.

(2) Application of optical compensation layer (production of optical compensation film)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the stretched and unstretched cellulose acylate film, and further optically anisotropic It is formed by providing a sex layer.

[Alignment film]
An orientation film is provided on the surface-treated stretched and unstretched cellulose acylate film of the present invention. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the optical compensation film 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.
The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodget method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, the cross-linking has a function of binding a side chain having a crosslinkable functional group (for example, a double bond) to the main chain, or aligning liquid crystal molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are most preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, and more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation film can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specifically, for example, those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216, and the like can be mentioned. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.
Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained.

  The alignment film can be basically formed by applying the polymer, which is an alignment film forming material, on a transparent support containing a crosslinking agent, followed by heat drying (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optically anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

The alignment film is provided on the stretched / unstretched cellulose acylate film or on the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.
When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing film being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can be any. Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
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]
As rod-like liquid crystalline molecules, 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 Chemical Chemistry of the Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), and the 142nd 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 crystalline 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, polymerization described in paragraphs [0064] to [0086] of JP-A-2002-62427 is described. And a polymerizable liquid crystal compound.

[Disc 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. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, 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 the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film 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 major axis orientation direction can also be adjusted by selecting liquid crystalline molecules and additives as described above.

[Other compositions of optically anisotropic layer]
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. 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 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.

  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.

The polymer used together with the discotic liquid crystalline molecules is preferably capable of changing the tilt angle of the discotic liquid crystalline molecules.
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 in the range of 0.1 to 8% by mass with respect to the liquid crystalline 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 polymerizable 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 photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (US Pat. No. 2,448,828). No. description), α-hydrocarbon substituted aromatic acyloin compounds (U.S. Pat. No. 2,722,512), polynuclear quinone compounds (U.S. Pat. Nos. 3,046,127 and 2,951,758). In each specification), a combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compound (Japanese Patent Laid-Open No. 60-105667), U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in U.S. 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.

Light irradiation for polymerizing liquid crystalline molecules is preferably performed using ultraviolet rays.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm ² More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. Further, a protective layer may be provided on the optically anisotropic layer.

It is also preferable to combine this optical compensation film and a polarizing film. 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 film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film 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 tilt angle between the polarizing film 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 vertical or horizontal direction of the liquid crystal cell. Is preferred. 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) Application of antireflection film (antireflection film)
The antireflection film generally comprises a low refractive index layer which is also an antifouling layer and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer). It is provided on (the cellulose acylate film of the present invention).
Colloidal metal as a multilayer film with transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes formed by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, or metal compound sol-gel method such as metal alkoxide Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.

On the other hand, various antireflective films formed by laminating and applying a thin film in which inorganic particles are dispersed in a matrix have been proposed as an antireflective film having high productivity.
The antireflection film which consists of the antireflection layer which provided the anti-glare property in which the surface of the uppermost layer has the shape of fine unevenness to the antireflection film by application | coating as mentioned above is also mentioned.
The cellulose acylate film of the present invention can be applied to any of the above-mentioned methods, but a coating method (coating type) is particularly preferable.

[Layer structure of coating type antireflection film]
An antireflective film comprising at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) in this order on a substrate (cellulose acylate film in the present invention) is a refractive that satisfies the following relationship: Designed to have a rate.
The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. Also good.

Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle size of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). , Anionic compounds or organometallic coupling agents: JP 2001-310432 A, etc., core-shell structure with high refractive index particles as the core (JP 2001-166104 A, etc.), specific dispersant combined use (For example, JP-A-11-153703, US Pat. No. 6,210,858, JP-A-2002-27776069, etc.) and the like.
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

Further, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The middle refractive index layer is the same layer as the high refractive index layer except for the refractive index, and the middle refractive index layer preferably has a refractive index of 1.50 to 1.70.

[Low refractive index layer]
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, and conventionally known means for a thin film layer made of a silicone compound into which silicone is introduced, a fluorine-containing compound into which fluorine is introduced, or the like can be applied.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
Examples of the fluorine-containing compound include paragraphs [0018] to [0026] of JP-A-9-222503, paragraphs [0019] to [0030] of JP-A-11-38202, and JP-A-2001-2001. No. 40284, paragraph numbers [0027] to [0028], JP 2000-284102 A, paragraph Nos. [0012] to [0077] of JP 2003-26732 A, paragraphs of JP 2004-45462 A And compounds described in the numbers [0030] to [0047].

The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.

Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

[Hard coat layer]
The hard coat layer is provided on the surface of the stretched / unstretched cellulose acylate film in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the stretched / unstretched cellulose acylate film and the high refractive index layer. Moreover, it is also preferable to coat directly on a stretched / unstretched cellulose acylate film without providing an antireflection layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrous functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.

Specific examples of the composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.
The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400. Moreover, in the Taber test according to JIS K5400, the smaller the amount of wear of the test piece before and after the test, the better.

[Forward scattering layer]
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

[Other layers]
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

[Coating method]
Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.

[Anti-glare function]
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Wherein) and the like.

<Liquid crystal display device>
The liquid crystal display device of the present invention is formed using the above-mentioned polarizing plate, optical compensation film, and antireflection film. Each liquid crystal mode in which these films are used will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal display device 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.

(OCB mode liquid crystal display)
The OCB mode liquid crystal display device 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. A liquid crystal display device using a bend alignment mode liquid crystal cell is 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 referred to as an OCB (Optically Compensated 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 VA mode liquid crystal display device is characterized in that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes aligned substantially vertically and aligned substantially horizontally when a voltage is applied, Liquid crystal cell with multi-domain mode (MVA mode) (described in SID97, Digest of tech. Papers 28 (1997) 845), (3) Substantially vertical alignment of rod-like liquid crystalline molecules when no voltage is applied (N-ASM mode) liquid crystal cell (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4 The liquid crystal cell of SURVAIVAL mode (published in LCD International 98) are included.

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in a plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with or without voltage application. Is the feature. 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.

(Other liquid crystal display devices)
ECB mode, STN (Super Twisted Nematic) mode, FLC (Ferroelectric Liquid Crystal) mode, AFLC (Anti-Ferroelectric Liquid Crystal) mode, ASM (Axially Symmetrical Alignment mode) Can be compensated for. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device. It is also advantageously used as an optical compensation sheet for a GH (Guest-Host) type reflective liquid crystal display device.
The uses of these detailed cellulose derivative films described above are described in detail in the technical reports of the Japan Society of Invention (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention), pages 45-59. .

[Usage]
The unstretched and stretched cellulose acylate films of the present invention are optical films, particularly for polarizing plate protective films, optical compensation sheets for liquid crystal display devices (also referred to as retardation films), optical compensation sheets for reflective liquid crystal display devices, and polarizing plates. It is useful as an optical film having both a protective function and an optical compensation function, and a support for silver halide photographic light-sensitive materials.

The measurement method used in the present invention is described below.
(1) Water permeability (moisture permeability coefficient)
A 70 mmφ sample was conditioned at 25 ° C./60% relative humidity and 40 ° C./95% relative humidity for 24 hours, respectively, with a moisture permeation tester (KK-70907, Toyo Seiki Co., Ltd.) according to JIS Z-0208. The amount of water per unit area was calculated (g / m ² · 24 hr). And the water vapor transmission rate was calculated | required by the mass before humidity-mass before humidity control.

(2) Contact angle of water Using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-X type contact angle meter), pure water is used as the liquid in a dry state (25 ° C./60% relative humidity). Then, a droplet having a diameter of 3.0 mm was formed on the needle tip, and this was brought into contact with the surface of the film to form a droplet. The angle between the tangent to the liquid surface at the point where the solid liquid is in contact with the solid surface and the angle containing the liquid was defined as the contact angle.
For each film, in a 1 square meter (1 m × 1 m) plane, measure the contact angle at 20 points in total, 5 points at equal intervals in one direction and 4 points at equal intervals in the other direction. It was described as an average value.
The in-plane contact angle difference (variation) was determined by the difference between the maximum and minimum measured contact angles and is shown in Table 2.
When both surfaces of the film were subjected to saponification treatment, the difference (variation) in the contact angle between both surfaces was determined by the difference in the average values of 20 locations on each surface and listed in Table 2.

(3) Substitution degree of cellulose acylate The substitution degree of acyl group is determined according to the method according to ASTM D-817-91, cellulose acylate is completely hydrolyzed, and the released carboxylic acid or its salt is subjected to gas chromatography or high speed It can be determined by quantifying by liquid chromatography, 1H-NMR or 13C-NMR, alone or in combination.

(4) Re, Rth
20 points were sampled at equal intervals in the width direction of the film, and after adjusting the humidity for 4 hours at 25 ° C. and 60% relative humidity, an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) was used. , At a wavelength of 590 nm from a direction tilted in increments of 10 ° from + 50 ° to −50 ° from the normal to the film surface with the slow axis as the rotation axis at 25 ° C. and a relative humidity of 60%. From the measurement of the phase difference value, an in-plane retardation value (Re) and a retardation value in the film thickness direction (Rth) were calculated. The average values of these 20 points are shown in Table 2 as Re and Rth.

(5) Tg measurement 10 mg of a sample is put into a DSC measurement pan. This was heated from 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 from 30 ° C. to 250 ° C., and the temperature at which the baseline started to deviate from the low temperature side was shown in Table 1 as Tg.

(6) Moisture content A 7 mm × 35 mm sample was measured by a Karl Fischer method using a moisture meter 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).

(7) Transmittance Transmittance was measured using a spectrophotometer (Murakami Color Research Laboratory, DOT-3).
This is a Y value obtained by performing visibility correction with a Z8701 two-degree field of view (C light source).

(8) Polarization degree The polarization degree is the transmittance (H90) obtained by superimposing the transmittance (H0) when two identical polarizing films are superposed on each other so that the polarization axes are parallel to each other. It measured according to the measurement of the transmittance | permeability of this, and calculated | required from the following formula | equation. The polarized light transmittance (H0) and the orthogonal transmittance (H90) are Y values with corrected visibility.
Polarization (%) = {(H0 -H90 ) / (H0 + H90)} 1/2 × 100

  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 150 parts by weight of cellulose (hardwood pulp) and 75 parts by weight of acetic acid were placed in a reaction vessel equipped with a cooling device and a reflux device and stirred for 4 hours while heating at 60 ° C. did. The reaction vessel was cooled to 2 ° C.
Separately, a mixture of 1545 parts by weight of propionic acid anhydride and 10.5 parts by weight of sulfuric acid was prepared as an acylating agent, cooled to −20 ° C., and then put into a reaction vessel containing the above pretreated cellulose at once. added. After 30 minutes, the external temperature was gradually raised, and after 2 hours from the addition of the acylating agent, the internal temperature was adjusted to 30 ° C., and the internal temperature was kept at 30 ° C. and further stirred for 3 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 120 g of 25% by mass hydrous acetic acid cooled to 5 ° C. was added over 1 hour. The internal temperature was raised to 40 ° C. and stirred for 1.5 hours. Next, a solution obtained by dissolving magnesium acetate tetrahydrate corresponding to twice the mole of sulfuric acid in 50% by mass of hydrous acetic acid was added to the reaction vessel, and the mixture was stirred for 30 minutes. 25% by mass hydrous acetic acid, 33% by mass hydrous acetic acid, 50% by mass hydrous acetic acid and water were added in this order to precipitate cellulose acetate propionate. The obtained cellulose acetate propionate precipitate was washed with warm water. After stirring in a 0.005 mass% calcium hydroxide aqueous solution at 20 ° C. for 0.5 hour, the solution was removed and vacuum dried at 70 ° C.
According to ¹ H-NMR and GPC measurement, the obtained cellulose acetate propionate had an acetylation degree of 0.30, a propionylation degree of 2.63, and a total substitution degree of 2.93.

[Synthesis Example 2] Synthesis of cellulose acetate butyrate 100 parts by weight of cellulose (hardwood pulp) and 135 parts by weight of acetic acid were placed in a reaction vessel equipped with a cooling device and a reflux device and stirred for 4 hours while heating at 60 ° C. . The reaction vessel was cooled to 2 ° C.
Separately, a mixture of 1080 parts by weight of butyric anhydride and 10.0 parts by weight of sulfuric acid was prepared as an acylating agent, cooled to −20 ° C., and then added to a reaction vessel containing pretreated cellulose at once. After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 5 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 2400 g of 12.5% by mass aqueous acetic acid cooled to about 5 ° C. was added over 1 hour. The internal temperature was raised to 40 ° C. and stirred for 1 hour. Next, a solution obtained by dissolving magnesium acetate tetrahydrate corresponding to twice the mole of sulfuric acid in 50% by mass of hydrous acetic acid was added to the reaction vessel, and the mixture was stirred for 30 minutes. 25% by mass aqueous acetic acid, 33% by mass aqueous acetic acid, 50% by mass aqueous acetic acid and water were added in this order to precipitate cellulose acetate butyrate. The obtained cellulose acetate butyrate precipitate was washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution for 0.5 hour, and then drained and dried at 70 ° C. under reduced pressure. The obtained cellulose acetate butyrate had a degree of acetylation of 0.84, a degree of butyrylation of 2.12 and a degree of total substitution of 2.96.

<Example 1> Melt film formation of cellulose acylate film (1) Preparation of cellulose acylate From the methods of cellulose acylate synthesis examples 1 and 2 described above, composition of acylating agent, reaction temperature and time of acylation, part The same synthesis was carried out by changing the hydrolysis temperature and time. Depending on the desired degree of acyl substitution, cellulose may be acylated (selected from acetic acid, acetic anhydride, propionic acid, propionic anhydride, butyric acid, butyric anhydride, alone or in combination), and as a catalyst Sulfuric acid was mixed and 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 obtain cellulose acylates having different types of acyl groups and different degrees of substitution shown in Table 1.

(Degree of polymerization measurement method)
About 0.2 g of completely dried cellulose acylate was precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (mass ratio). This was measured with an Ostwald viscometer for the number of seconds dropped at 25 ° C., and the degree of polymerization was determined by the following equation.
η _rel = T / T ₀
[Η] = ln (η _rel ) / C
DP = [η] / Km
[In the formula, T is the number of seconds that the sample is dropped, T ₀ is the number of seconds that the solvent is dropped, ln is the natural logarithm, C is the concentration (g / L), and Km is 6 × 10 ⁻⁴ . ]

(2) Pelletization of cellulose acylate The above-mentioned cellulose acylate was dried at 100 ° C. for 3 hours to have a moisture content of 0.1% by mass or less, and optical modifiers B-1 to B-6 selected from the following: Either amount was added in the amount shown in Table 1.
Optical adjuster

The plasticizer was selected from the following (described in Table 1) and added.
Plasticizer A: Polyethylene glycol (molecular weight 600)
Plasticizer B: Glycerin diacetate oleate Plasticizer C: Biphenyl diphenyl phosphate Plasticizer D: Dioctyl adipate

Furthermore, silicon dioxide part particles (Aerosil R972V) 0.05% by mass in all levels, UV absorber (2- (2′-hydroxy-3 ′, 5-di-t-butylphenyl) -benzotriazole: 0.05% by mass %, 2,4-hydroxy-4-methoxy-benzophenone: 0.1 mass%), stabilizer (bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite) (PEP-24G) 0.3 mass % Was added.
Using these two-screw kneading extruders with vacuum exhaust, after screw extrusion from a die at a screw rotation speed of 300 rpm, a kneading time of 40 seconds, and an extrusion rate of 200 kg / hr, solidified in water at 60 ° C., cut into a diameter of 2 mm and a length of 3 mm. A cylindrical pellet was obtained.

(3) Melt Film Formation Cellulose acylate pellets prepared by the above method were dried with a vacuum dryer at 100 ° C. for 3 hours. This was put into a hopper at 80 ° C., the screw diameter was 60 mm, L / D = 40, and the compression ratio was 3.5. The barrel temperature was increased from 150 ° C. to 235 ° C. from the inlet toward the outlet.
After melting, the melt was filtered through a 3 μm filter, extruded from a die having a slit interval of 0.8 mm, and the melt was solidified by a multiple casting drum shown in FIG. 2 under the casting conditions shown in Table 1. At this time, electrostatic application was performed 10 cm at each end using each level of electrostatic application method (10 kV wire was placed 10 cm from the point where the melt was attached to the casting drum). 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. And rolled up 3000 m. The width of the unstretched film thus obtained was 1.5 m at each level.

  The water permeability, Re, Rth, contact angle of water, difference between in-plane and out-of-plane contact angles, and Tg of the cellulose acylate thus obtained were determined and listed in Table 1.

(4) Stretching The cellulose acylate film thus obtained was stretched at a magnification described in Table 1 at (Tg + 15) ° C. Thereafter, trimming was performed by 5% at each end. These Re and Rth were measured by the above method and listed in Table 2.

(5) Production of Polarizing Plate (5-1) Saponification of Cellulose Acylate Film An unstretched and stretched cellulose acylate film was saponified using one of the following saponification methods. It described in Table 1.
(I) Immersion saponification A 2.0 to 4.0 mol / L aqueous solution of NaOH was used as a saponification solution.
This was temperature-controlled at 41-80 degreeC, and the cellulose acylate film was immersed for 2 minutes.
Then, after being immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water-washing bath.
The saponification solution and saponification conditions are shown in Table 1, respectively.
(Ii) Coating saponification 80 parts by mass of water is added to 10 parts by mass of iso-propanol, and KOH is dissolved to 2.5 mol / L, and the temperature is adjusted to 60 ° C. as a saponification solution. Using.
This was coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, using a hot water spray at 50 ° C., it was washed by spraying at 10 L / m ² · min for 1 minute.

The surface condition (foreign matter, turbidity) of the saponified cellulose acylate film was evaluated according to the following criteria.
First, the entire width of the saponification film was cut into a length of 1 m, and the sample was observed visually and with a magnifying glass while transmitting light on the shaukasten, using the following ranks. evaluated.
[Rank]
A: No foreign matter or turbidity was observed.
(Evaluation by 10 people, no one can recognize)
Δ: Foreign matter and turbidity were weakly generated.
(Level evaluated by 10 people and recognized by 2 to 5 people)
X: Foreign matter and turbidity were strongly generated.
(Level evaluated by 10 people and recognized by 6 or more people)

  The saponified cellulose acylate film of the present invention was excellent in surface shape, and no foreign matter or turbidity was observed at all.

(5-2) Production of Polarizing Film According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls and stretched in the longitudinal direction to prepare a polarizing film having a thickness of 20 μm.

(5-3) Bonding The polarizing film thus obtained and the saponified unstretched and stretched cellulose acylate film were combined with a 3% aqueous solution of PVA (PVA-117H manufactured by Kuraray Co., Ltd.) as an adhesive. As shown in Table 1, the polarizing axis and the cellulose acylate film were bonded together in the following combinations so that the longitudinal directions thereof were parallel (the selected configurations are shown in Table 1). “Fujitac TD80UF” is an unstretched cellulose triacetate film manufactured by Fuji Photo Film Co., Ltd.
Polarizing plate A: Unstretched cellulose acylate film / polarizing film / Fujitac TD80UF
Polarizing plate B: Unstretched cellulose acylate film / polarizing film / unstretched cellulose acylate film Polarizing plate C: Stretched cellulose acylate film / polarizing film / Fujitac TD80UF
Polarizing plate D: Stretched cellulose acylate film / polarizing film / unstretched cellulose acylate film Polarizing plate E: Stretched cellulose acylate film / polarizing film / stretched cellulose acylate film (In the polarizing plates B, D and E, stretched The same kind of cellulose acylate was used for unstretched cellulose acylate)

(5-4) Durability Evaluation After the polarizing plate thus obtained was held at 80 ° C. and 90% relative humidity for 1000 hours (thermo treatment), the transmittance and polarization degree were measured, before and after the thermo treatment, The difference in the degree of polarization was determined and listed in Table 2. What carried out this invention showed favorable durability.
Moreover, the adhesiveness of the polarizing plate before and after the thermo treatment was subjected to a thermo treatment for 1000 hours while maintaining the polarizing plate shown in Table 1 in an environment of 80 ° C. and 90% relative humidity. The adhesiveness between the cellulose acylate film and the polarizing film was determined according to the following criteria, and the area ratio of peeling of the polarizing plate was determined by the following formula and listed in Table 2.
Peeling area ratio (%) = Peeling area / Total area of polarizing plate × 100
In addition, a laminate was prepared so that the polarization axis and the longitudinal direction of the cellulose acylate film were orthogonal and 45 °, and the same evaluation was performed. In either case, the results were the same as those obtained when the films were bonded in parallel.
As shown in Table 2, the polarizing plate using the unstretched and stretched cellulose acylate of the present invention has little decrease in the degree of polarization in a high temperature and high humidity environment, does not peel off from the polarizing film, and has durability and adhesiveness. It was excellent. On the other hand, in Comparative Examples 1-5 other than this invention, the fall of the polarization degree in a high temperature, high humidity environment was large, there existed peeling after a thermo process, and it was inferior to durability. Further, in Comparative Example 6 produced according to the method of Example 1 posted in Patent Document 2 (Japanese Patent Laid-Open No. 2000-352620), the degree of polarization after thermostating was severely reduced, and the peeled area Was found to be even larger and the worst in durability and adhesion.

(6) Production of optical compensation film and liquid crystal display element The observer-side polarizing plate provided in the 22-inch liquid crystal display device (manufactured by Sharp Corporation) using a VA type liquid crystal cell is peeled off. In the case of the phase difference polarizing plates A and B, the polarizing plate is removed. In the case of the polarizing plates C, D and E, the polarizing plate and the phase difference plate are removed, and the cellulose acylate film is placed on the liquid crystal cell side through an adhesive. Affixed to the observer side. A liquid crystal display device was manufactured by arranging the transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side to be orthogonal to each other.
After holding this in an environment of 80 ° C. and 90% relative humidity for 1000 hours, the transmittance, polarization degree, peelability and the like were evaluated. In the case of carrying out the present invention, there was no peeling from the polarizing film, the decrease in the degree of polarization was small, and the durability was excellent.

Further, even when the cellulose acylate film of the present invention was used in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, a good optical compensation film could be produced.
In place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, even if an optical compensation filter film is produced by changing to the cellulose acylate film of the present invention, a good optical compensation film is produced. did it.

  Further, the polarizing plate and the retardation polarizing plate of the present invention are applied to the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecules described in Example 1 of JP-A-9-26572. Including an optically anisotropic layer, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIGS. 10 to 10 of JP-A-2000-154261. When used in the 20-inch OCB type liquid crystal display device described in No. 15 and the IPS type liquid crystal display device shown in FIG. 11 of JP-A No. 2004-12731, a good liquid crystal display element was obtained.

(7) Production of low-reflection film A cellulose acylate film of the present invention was produced in accordance with Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Invention Association). did. After holding this in an environment of 80 ° C. and 90% relative humidity for 1000 hours, the transmittance, polarization degree, peelability and the like were evaluated. When the present invention was implemented, good results similar to those obtained with the polarizing plate were obtained.
Furthermore, the cellulose acylate film of the present invention is applied to a liquid crystal display device described in Example 1 of JP-A-10-48420, a 20-inch VA liquid crystal display described in FIGS. 2 to 9 of JP-A-2000-154261. Evaluation was made on the outermost layer of the device, the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP 2000-154261 A, and the IPS type liquid crystal display device shown in FIG. 11 of JP 2004-12731 A. As a result, a good liquid crystal display element was obtained.

<Example 2> Melt film formation by the touch roll method For the present invention 1, 5, 14 and the present invention 22 to the present invention 24, the touch roll described in Example 1 of JP-A-11-235747 (double suppression) (Thick metal outer cylinder thickness was set to 3 mm), and touch roll film formation was carried out under the conditions described in Table 3 (except that touch roll film formation was performed) under the same conditions. Implementation).
The planar shape (thickness unevenness and fine unevenness) of the unstretched cellulose acylate film thus obtained was measured and evaluated by the following method.

(Thickness unevenness measurement)
Sampling was performed at a width of 35 mm over the entire width of the cellulose acylate film (TD sample). The central part in the width direction was sampled 2 mm long with a width of 35 mm (MD sample). TD sample and MD sample were measured with a continuous thickness meter (FILM THICKNESS TESTER KG601A, manufactured by ANRITSU (Anritsu Electric Co., Ltd.)), and the average of (maximum value−average value) and (average value−minimum value) did.

(Fine unevenness (die line) measurement)
The cellulose acylate film was measured under the following conditions using a three-dimensional surface structure analysis microscope (New View 5022 manufactured by Zygo).
Objective lens: 2.5 times Image zoom: 1 time Measurement field of view: 2.8 mm in the width direction (TD), 2.1 mm in the longitudinal direction (MD)
Among them, the number of peaks (convex portions) having a height of 0.01 μm to 30 μm and valleys (concave portions) having a depth of 0.01 μm to 30 μm were counted. However, a convex part and a recessed part point out what is continuously 1 mm or more continuously in MD direction. The number of the convex portions and concave portions was divided by the measurement width (2.8 mm) and then multiplied by 100 to obtain the number of convex portions and concave portions per 10 cm. The above measurement was performed by measuring 30 points at equal intervals over the entire width of the formed sample film and averaging it, thereby obtaining the number of convex portions and concave portions per 10 cm width.

  As shown in Table 3, it was confirmed that the fine unevenness (die line) and thickness unevenness formed on the film formed by melt film formation using the touch roll method were further improved. Moreover, it was confirmed that Rth of the film formed using the touch roll method is improved, and the optical property expression area is widened. Furthermore, it was confirmed by the frame mounting evaluation that the frame unevenness occurrence area ratio was reduced.

  Furthermore, a touch roll similar to that of the first example of the pamphlet of WO 97/28950 (with a sheet forming roll) is used (however, the cooling water used for the metal outer cylinder starts at a temperature of 18 ° C. When the film was formed using a touch roll under the conditions described in Table 3, the same results as in Table 3 were obtained.

  According to the present invention, it has an appropriate water permeability, excellent adhesion to a polarizing film, a small contact angle of water after saponification treatment, and a small difference in contact angle between in-plane or both surfaces. In addition, it is possible to provide a cellulose acylate film capable of satisfying the temporal stability of polarization degree and good adhesion required in a high temperature and high humidity environment, and a method for producing the same. If the cellulose acylate film provided by the present invention is used, a high-quality polarizing plate, an optical compensation film having a polarizing plate protection function and a retardation compensation function, an antireflection film, and a liquid crystal display device using these films are provided. can do. Therefore, the present invention has high industrial applicability.

It is sectional drawing of the one aspect | mode of the melt extruder provided with the screw. It is sectional drawing of the one aspect | mode of a multiple type casting drum. It is sectional drawing of the one aspect | mode of the multiple type casting drum provided with the touch roll.

Explanation of symbols

12 Cellulose Acylate Film 14 Multiple Casting Drum 23 Touch Roll 24 Die 26 First Casting Drum 28 Second Casting Drum 30 Third Casting Drum 31 Nip Roll 60 Extruder 62 Cylinder 64 Screw Shaft 66 Flight 68 Single Screw 80 Supply Port 82 Discharge port A Supply unit B Compression unit C Weighing unit

Claims (15)

A cellulose reed formed by melt casting, having a water permeability of 150 to 800 g / m ² · 24 hr at 40 ° C. and a relative humidity of 95%, and satisfying the following formulas (1) to (3) Rate film.
Formula (1): 2.0 ≦ X + Y ≦ 3.0
Formula (2): 0 ≦ X ≦ 2.0
Formula (3): 1.2 ≦ Y ≦ 3.0
[Wherein, X represents the substitution degree of the acetyl group, and Y represents the total substitution degree of the acyl group having 3 to 7 carbon atoms. ]   2. The cellulose acylate film according to claim 1, wherein the cellulose acylate film is subjected to alkali saponification treatment, the contact angle of water is 45 ° or less, and the difference in in-plane distribution of the contact angle is within 5 °.   The cellulose acylate film according to claim 2, wherein a difference in contact angle between both surfaces of the film is within 5 °.   2. The in-plane retardation (Re) of the unstretched cellulose acylate film is 0 ≦ Re ≦ 20 nm, and the retardation in the thickness direction (Rth) is 0 ≦ Rth ≦ 60 nm. The cellulose acylate film according to any one of -3.   After the cellulose acylate film according to any one of claims 1 to 4 is stretched by 1 to 250% in at least one direction, the in-plane retardation (Re) is 0 ≦ Re ≦ 300 nm, and the thickness The cellulose acylate film according to claim 1, wherein a direction retardation (Rth) is 0 ≦ Rth ≦ 500 nm. A method for producing a cellulose acylate film, wherein a cellulose acylate is formed into a film by melt casting using a multiple casting drum provided with a plurality of casting drums,
The surface temperature of the first casting drum on which the cellulose acylate extruded from the die is melt cast is (Tg-30) ° C. to (Tg + 15) ° C., and each casting drum is provided at both ends of the roll surface. A method for producing a cellulose acylate film, wherein the difference in temperature is 10 ° C. or less.   The method for producing a cellulose acylate film according to claim 6, wherein the film is formed using a touch roll.   The method for producing a cellulose acylate film according to claim 6 or 7, wherein the film-like cellulose acylate formed by the multiple casting drum is subjected to an alkali saponification treatment at a temperature of 41 to 80 ° C. .   The cellulose acylate film according to any one of claims 1 to 5, wherein the cellulose acylate film is produced by the method for producing a cellulose acylate film according to any one of claims 6 to 8.   A polarizing plate comprising at least one layer of the cellulose acylate film according to any one of claims 1 to 5 or 9 laminated on a polarizing film.   The polarizing plate according to claim 10, wherein the transmittance is 42.0% or more and the degree of polarization is 99.0% or more.   The polarizing plate according to claim 10 or 11, wherein a decrease in the degree of polarization after holding for 1000 hours in an environment of 80 ° C and 90% relative humidity is 1% or less.   An optical compensation film using the cellulose acylate film according to claim 1.   An antireflection film comprising the cellulose acylate film according to claim 1.   The cellulose acylate film according to any one of claims 1 to 5 and 9, the polarizing plate according to any one of claims 10 to 12, the optical compensation film according to claim 13, and the claim 14. A liquid crystal display device comprising one or more films selected from the group consisting of the antireflection films described above.

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