JP2008138015A - Cellulose acylate composition, cellulose acylate film, optical compensation sheet, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film capable of controlling values of in-plane retardation (Re) and retardation (Rth) in the thickness direction within a wide range with a simple process and to provide an optical compensation sheet, a polarizing plate and a liquid crystal display device using the film. <P>SOLUTION: A cellulose acylate composition comprises a polymer having a repeating unit represented by general formula (1) (wherein, X and Y contain each a monocyclic or a condensed polycyclic aliphatic group or aromatic group) and a cellulose acylate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose acylate film, an optical compensation sheet, a polarizing plate and a liquid crystal display device. More specifically, the present invention relates to a wide range of in-plane retardation (Re) values and thickness direction retardation (Rth) values. The present invention relates to a cellulose acylate film that can be freely controlled, and an optical compensation sheet, a polarizing plate and a liquid crystal display device using the same.

  In recent years, with the widespread use of liquid crystal display devices, demands for display performance and durability have increased, response speed has improved, and a wider viewing angle such as contrast and color balance when viewed from an oblique direction with respect to the display image. It has become a problem to compensate with. In order to solve these problems, VA (Vertical Alignment), OCB (Optical Compensated Bend), or IPS (In-Plane Switching) display devices have been developed. There is a demand for an optical film material having a foundation development property. In particular, the retardation film is required to control the in-plane retardation (Re) and the thickness direction retardation (Rth) according to each of various liquid crystal systems. Optical films with controlled retardation values in response to such requirements have been studied. For example, Patent Document 1 discloses an optical film using a fatty acid cellulose ester having an acetyl group and a propionyl group. The expression range of Re and Rth can be expanded by stretching the optical film. However, in the above cellulose ester, the limit of birefringence is limited, and sufficient birefringence according to diversified liquid crystal systems has not been developed.

An optical film has been proposed in which a birefringence of the whole film is increased by developing a polymer solution such as polyamide or polyimide on a cellulose acylate film and then orienting it by subjecting it to stretching or shrinking (for example, , See Patent Document 2). Although this method is useful as a method for controlling the birefringence of the cellulose acylate film, it has to be applied after the cellulose acylate is formed, and there is a problem that the process is complicated.
Furthermore, a mixture and a film in which an aliphatic-aromatic copolyester is blended with a cellulose ester are disclosed as means for improving physical properties, mechanical strength, and the like (see, for example, Patent Document 3). However, the polyester disclosed in Patent Document 3 has a tendency to lower the glass transition temperature of the cellulose acylate film, and gives an unfavorable property depending on the application when considering application as an optical film. was there.
JP 2001-188128 A JP 2006-206826 A JP 2003-128768 A

  In view of the above problems, the present invention provides a cellulose acylate film capable of controlling the values of in-plane retardation (Re) and thickness direction retardation (Rth) in a wide range by a simple process, and optical using the same. An object is to provide a compensation sheet, a polarizing plate, and a liquid crystal display device.

〔一般式（１）中、Ｘは単環式または縮合多環式の脂肪族基または芳香族基を含有し、構成する炭素原子数が４〜３０である４価の連結基を表す。Ｙは単環式または縮合多環式の脂肪族基または芳香族基を含有し、構成する炭素原子数が４〜３０である２価の連結基を表す。〕 The above object of the present invention has been achieved by the following means.
[1] A cellulose acylate composition comprising a polymer compound having a repeating unit represented by the following general formula (1) and cellulose acylate.

[In General Formula (1), X represents a monovalent or condensed polycyclic aliphatic group or aromatic group, and represents a tetravalent linking group having 4 to 30 carbon atoms. Y represents a divalent linking group containing a monocyclic or condensed polycyclic aliphatic group or aromatic group and having 4 to 30 carbon atoms. ]

〔一般式（２）中、Ｒ¹は独立に置換基を表し、置換基が複数ある場合、それぞれの置換基は同じであっても異なっていてもよい。ｐは０〜４の整数を表し、ｎは正の整数を表す。〕 [2] The cellulose acylate composition as described in the item [1], wherein Y in the general formula (1) includes a structure represented by the following general formula (2).

[In General Formula (2), R ¹ independently represents a substituent, and when there are a plurality of substituents, each substituent may be the same or different. p represents an integer of 0 to 4, and n represents a positive integer. ]

[3] The cellulose acylate composition as described in the item [1] or [2], wherein X in the general formula (1) is a monocyclic or condensed polycyclic aliphatic group.
[4] The cellulose acylate composition according to any one of [1] to [3], wherein X in the general formula (1) is a cyclohexane ring.
[5] The cellulose acyl of any one of [1] to [4], wherein the cellulose acylate is any one of cellulose acetate, cellulose acetate propionate, or cellulose acetate butyrate. Rate composition.
[6] The mass ratio of the polymer compound having a repeating unit represented by the general formula (1) and cellulose acylate is 0.001: 1 to 1: 1, [1] The cellulose acylate composition according to any one of to [5].

[7] A cellulose acylate dope composition comprising the cellulose acylate composition according to any one of [1] to [6].
[8] An optical film comprising the cellulose acylate composition according to any one of [1] to [6], wherein an in-plane retardation (Re) and a thickness direction retardation (Rth) are obtained. A cellulose acylate film represented by the following formulas (I) and (II):
Formula (I): 0 nm ≦ Re (590) ≦ 200 nm
Formula (II): 0 nm ≦ Rth (590) ≦ 400 nm
(In the formula, Re (590) and Rth (590) are values (unit: nm) at the wavelength λ = 590 nm.)
[9] A retardation film using the cellulose acylate film according to the item [8].
[10] A polarizing plate comprising a polarizing film and two protective films sandwiching the polarizing film, wherein at least one of the two protective films is the cellulose acylate film of [8] or [9 ] The retardation film of claim | item, The polarizing plate characterized by the above-mentioned.
[11] An optical material having an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose acylate film according to the item [8] or the retardation film according to the item [9]. Compensation sheet.
[12] An antireflection film comprising an antireflection layer on the cellulose acylate film according to the item [8] or the retardation film according to the item [9].
[13] The cellulose acylate film described in the item [8], the retardation film described in the item [9], the polarizing plate described in the item [10], the optical compensation sheet described in the item [11], and [12 ] At least 1 sort (s) selected from the group which consists of an anti-reflective film as described in an item] is used.
[14] A method for producing a cellulose acylate film, which is prepared using the dope composition according to the item [7].

When the cellulose acylate composition of the present invention is in the form of a film, the values of in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled in a wide range.
By using the cellulose acylate dope composition of the present invention, it is possible to form a cellulose acylate film in which the values of in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled in a wide range.
Moreover, the cellulose acylate film of the present invention can be suitably used for, for example, a polarizing plate protective film, a polarizing plate, a liquid crystal display device and the like.

  Hereinafter, the present invention will be described in detail. The following description may be made based on representative 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.

The cellulose acylate composition of the present invention comprises cellulose acylate and a polymer compound having a repeating unit represented by the general formula (1). As will be described later, the cellulose acylate composition of the present invention can take various forms such as particles, solutions, and films, and the form is not particularly limited.
First, the cellulose acylate preferably used in the cellulose acylate composition of the present invention will be described in detail.

<Cellulose acylate>
(Basic structure)
Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. In the present invention, the degree of substitution means the total of the ratio of substitution of the hydroxyl group of cellulose for each of the 2-position, 3-position and 6-position (for example, 100% esterification is represented as substitution degree = 1). . In addition, when natural cellulose raw materials contain components other than cellulose, such as polymers (hemicellulose) of constituent sugars other than glucose (for example, xylose, mannose, etc.) and lignin corresponding to the organism or purification method from which they are derived. However, in the present invention, polymers produced using cellulose raw materials containing these as raw materials are also collectively referred to as cellulose acylate.

(Degree of substitution)
The cellulose acylate used in the present invention preferably satisfies the following formulas (1) to (3). That is, in the following formulas (1) to (3), the following substitution degree A and substitution degree B are within the ranges defined in the following formula (2) or (3), respectively, and the substitution degree The total of A and B is preferably in the range defined by the following formula (1).
Formula (1): 2.0 <= A + B <= 3
Formula (2): 0 ≦ A ≦ 3
Formula (3): 0 ≦ B ≦ 3
(In the formula, A represents the degree of substitution of the acetyl group with respect to the hydrogen atom constituting the hydroxyl group of cellulose, and B represents the degree of substitution of the acyl group having 3 to 22 carbon atoms with respect to the hydrogen atom constituting the hydroxyl group of cellulose.)
When a plurality of the aliphatic acyl groups are substituted in the cellulose compound, B represents the total degree of substitution of the substituted aliphatic acyl groups.

The cellulose acylate used in the present invention more preferably satisfies the following formulas (4) to (6). That is, in the following formulas (4) to (6), the following substitution degree A and substitution degree B are within the ranges defined in the following formula (5) or (6), respectively, and the substitution degree More preferably, the sum of A and B is within the range defined by the following formula (4).
Formula (4): 2.5 <= A + B <= 3
Formula (5): 0.3 <= A <= 3
Formula (6): 0 ≦ B ≦ 2.5

The cellulose acylate used in the present invention more preferably satisfies the following formulas (7) to (9). That is, in the following formulas (7) to (9), the following substitution degree A and substitution degree B are within the ranges defined in the following formula (8) or (9), respectively, and the substitution degree More preferably, the sum of A and B is within the range defined by the following formula (7).
Formula (7): 2.6 <= A + B <= 2.99
Formula (8): 0.5 <= A <= 2.99
Formula (9): 0 ≦ B ≦ 2.4

It is particularly preferable that the cellulose acylate used in the present invention satisfies the following formulas (10) to (12). That is, in the following formulas (10) to (12), the following substitution degree A and substitution degree B are within the ranges defined in the following formula (11) or (12), respectively, and the substitution degree It is particularly preferable that the sum of A and B is within the range defined by the following formula (10).
Formula (10): 2.7 ≦ A + B ≦ 2.98
Formula (11): 0.7 ≦ A ≦ 2.98
Formula (12): 0 ≦ B ≦ 2.3

When A + B is less than 1.5, the cellulose acylate is too hydrophilic, which is not preferable because the humidity dependency of the cellulose acylate film is deteriorated. If A + B is 2.0 or more, good properties will be exhibited depending on the use. However, when the cellulose acylate composition of the present invention is an optical film, 2.5 or more is preferable, and 2.6 or more is more preferable. It is especially preferable that it is 2.7 or more.
A can take any value as long as it is 0 or more and 3 or less, but the cellulose acylate film of the present invention preferably has a value of 0.3 or more, more preferably 0.5 or more, in order to exhibit preferable optical properties. 0.7 or more is particularly preferable. The upper limit is preferably 2.99 or less, more preferably 2.98 or less, from the viewpoint of properties such as cost and film surface condition.
B can take any value as long as it is 0 or more and 3 or less, but is preferably 2.5 or less in order for the cellulose acylate film of the present invention to exhibit preferable optical properties, mechanical properties and film-forming suitability. 2.4 or less is more preferable, and 2.3 or less is particularly preferable.

(Substituent whose degree of substitution is represented by B)
The substituent represented by B in the present invention is an acyl group having 3 to 22 carbon atoms, preferably 3 to 12 carbon atoms, more preferably 3 to 6 carbon atoms, and particularly preferably It has 3 to 4 carbon atoms. When the number of carbon atoms exceeds 22, the suitability for production decreases, and the glass transition temperature of the polymer may not be appropriate when used as a film.
Examples of preferred substituents include propionyl group, butyryl group, pentanoyl group, heptanoyl group, hexanoyl group, isobutyryl group, and pivaloyl group. More preferred are a propionyl group, a butyryl group, and a hexanoyl group, and particularly preferred are a propionyl group and a butyryl group.

(Concrete example)
Preferred examples of the cellulose acylate of the present invention include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate heptanoate, cellulose acetate hexanoate, and cellulose acetate pentanoate. More preferred examples include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate heptanoate, and cellulose acetate hexanoate. Particularly preferred examples of the cellulose acylate of the present invention are cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.

[Method for producing cellulose acylate]
General methods for synthesizing the cellulose compound of the present invention are described in JP-A-6-329561, JP-A-5-240848, Macromol. Chem. Phys., 1996, 197, 953-964, Macromol. Chem. Phys., 2002, 203, 961-967, Org. Biomol. Chem., 2004, Vol. 2, pages 402-407, described in detail in Non-Patent Documents 1 and 2 mentioned above, and can be applied as appropriate in the present invention.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As a cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
When the cellulose raw material is in the form of a sheet or a lump, it is preferably pulverized in advance, and the pulverization is preferably progressed until the cellulose is in the form of cotton, feathers, or powder.

(Activation process)
In the present invention, the cellulose raw material is preferably subjected to a pretreatment (activation) for contacting with an activator prior to esterification. As the activator, it is preferable to use a carboxylic acid (preferably acetic acid, propionic acid, butyric acid, particularly preferably acetic acid). The addition method can be selected from any method such as spraying, dripping and dipping, and the activation may take any temperature and time. The activator may contain water or a catalyst described later. Details of the activation process are also described in Japanese Patent Laid-Open No. 2006-45500.

(Acylation step)
In producing the cellulose acylate of the present invention, it is preferable to acylate cellulose by the presence of a catalyst. Specifically, it is preferable to acylate the hydroxyl group of cellulose by adding an acid anhydride of carboxylic acid to cellulose and reacting with Bronsted acid or Lewis acid as a catalyst. As the catalyst, sulfuric acid can be preferably used.
The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in JP-A Nos. 11-5851, 2002-212338, 2002-338601 and the like.

(Acid anhydride)
The acid anhydride of the carboxylic acid is preferably an acid anhydride having 2 to 7 carbon atoms as the carboxylic acid, such as acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride. Valeric anhydride, 3-methylbutyric anhydride, 2-methylbutyric anhydride, 2,2-dimethylpropionic anhydride (pivalic anhydride), hexanoic anhydride, 2-methylvaleric anhydride, 3 -Methylvaleric anhydride, 4-methylvaleric anhydride, 2,2-dimethylbutyric anhydride, 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, cyclopentanecarboxylic anhydride, heptane An acid anhydride, a cyclohexanecarboxylic acid anhydride, a benzoic acid anhydride etc. can be mentioned, More preferably, acetic anhydride, propionic acid anhydride, butyric acid anhydride, valeric acid anhydride, hexanoic acid anhydride, A anhydrides such as heptanoic acid anhydrides, particularly preferably acetic anhydride, propionic anhydride and butyric anhydride.

As a method for obtaining a cellulose acylate, it is preferable to use these acid anhydrides in combination. The mixing ratio is preferably determined according to the substitution ratio of the target mixed ester. 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, and it is especially preferable to add 1.3-10 equivalent.
In addition, as a method of mixed acylation, a method in which two kinds of carboxylic acid anhydrides are mixed or sequentially reacted is used, and a mixed acid anhydride of two kinds of carboxylic acids (for example, acetic acid / butyric acid mixed acid anhydride) is used. A method of synthesizing a mixed acid anhydride (for example, acetic acid / butyric acid mixed acid anhydride) in a reaction system using an acid anhydride (for example, acetic acid and butyric acid anhydride) of a carboxylic acid and another carboxylic acid as a raw material. The method of making it react with can also be used. Furthermore, a cellulose acylate having a total degree of substitution of less than 3 (for example, cellulose acetate having a degree of substitution of 2.4), an acid anhydride, an acid halide, etc. may be converted into a base catalyst (for example, pyridine, triethylamine, etc.) or an acid. It can also be obtained by reacting in the presence of a catalyst (for example, sulfuric acid, perchloric acid, etc.), and if necessary, a solvent. This method is particularly useful when an acyl group having 6 or more carbon atoms, which has a low reactivity with an acid anhydride, is introduced.

(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). Examples of preferable Bronsted acid include sulfuric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Examples of preferred Lewis acids include zinc chloride, tin chloride, antimony chloride, magnesium chloride and the like.

  As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. It is also preferable to use a combination of sulfuric acid and another catalyst. 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 ability, acyl substitution ratio, and the like. As such a solvent, dichloromethane, chloroform, carboxylic acid, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane and the like can be used, but carboxylic acid is preferable, for example, a carboxylic acid having 2 to 7 carbon atoms. Acids (eg acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2-dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid , 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, cyclopentanecarboxylic acid) and the like, more preferably Examples include acetic acid, propionic acid, and butyric acid. These solvents may be used as a mixture.

(Conditions for acylation)
When acylation is performed, an acid anhydride and a catalyst, and further, if necessary, a solvent may be mixed and then mixed with cellulose, or these may be separately mixed with cellulose. It is preferable to prepare a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent as an acylating agent and then react with cellulose. In order to suppress an increase in temperature in the reaction vessel due to reaction heat during acylation, the acylating agent is preferably cooled in advance. The cooling temperature is preferably −50 ° C. to 20 ° C., more preferably −35 ° C. to 10 ° C., and particularly preferably −25 ° C. to 5 ° C. The acylating agent may be added in a liquid state or may be frozen and added as a crystal, flake or block solid.

  Further, the acylating agent may be added to the cellulose at once, or may be added in divided portions. In addition, cellulose may be added to the acylating agent all at once, or may be added separately. When the acylating agent is added in portions, the same acylating agent or a plurality of different acylating agents may be used. Preferred examples are: 1) the acid anhydride and solvent mixture is added first, then the catalyst is added, 2) the acid anhydride, a mixture of part of the solvent and catalyst is added first, and then the rest of the catalyst 3) Add the acid anhydride and solvent mixture first, then add the catalyst and solvent mixture, 4) Add the solvent first, and the acid anhydride and catalyst mixture or Examples thereof include a method of adding a mixture of an acid anhydride, a catalyst and a solvent.

  Although acylation of cellulose is an exothermic reaction, in the method for producing cellulose acylate in the present invention, it is preferable that the maximum temperature reached during acylation is 50 ° C. or less. A reaction temperature of 50 ° C. or lower is preferred because depolymerization proceeds and problems such as difficulty in obtaining a cellulose acylate having a polymerization degree suitable for the use of the present invention do not occur. The maximum temperature achieved during acylation is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, still more preferably 35 ° C. or lower, and particularly preferably 30 ° C. or lower. The reaction temperature may be controlled using a temperature controller, or may be controlled by the initial temperature of the acylating agent. In addition, the reaction temperature can be controlled by reducing the pressure of the reaction vessel and using the heat of vaporization of the liquid component in the reaction system. Further, since the exotherm during the acylation is large in the initial stage of the reaction, it is possible to perform control such as cooling in the initial stage of the reaction and heating thereafter. The end point of acylation can be determined by means such as light transmittance, solution viscosity, temperature change of the reaction system, solubility of the reaction product in an organic solvent, and observation with a polarizing microscope.

  The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. A preferable acylation time is 0.5 to 24 hours, more preferably 1 to 12 hours, and particularly preferably 1.5 to 6 hours. If the reaction time is 0.5 hours, the reaction does not proceed sufficiently under normal reaction conditions. If the reaction time exceeds 24 hours, it is not preferable for industrial production.

(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 an acid anhydride, and preferred examples include water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing these. Can be mentioned. Moreover, the reaction terminator may contain a neutralizing agent described later. Upon addition of the reaction terminator, a large exotherm exceeding the cooling capacity of the reactor may occur, which may cause the degree of polymerization of the cellulose acylate to decrease, or the cellulose acylate may precipitate in an undesired form. In order to avoid such inconveniences, it is preferable to add a mixture of carboxylic acid such as acetic acid, propionic acid, butyric acid and water rather than directly adding water or alcohol, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of carboxylic acid and water can be used at any ratio, but the water content is 5 to 80% by mass, further 10 to 60% by mass, and particularly 15 to 50% by mass. % Is preferable.

  The reaction terminator may be added to the acylation reaction vessel or the reactant may be added to the reaction terminator vessel. The reaction terminator is preferably added over 3 minutes to 3 hours. If the addition time of the reaction terminator is 3 minutes or more, the exotherm becomes too large, causing a decrease in the degree of polymerization, insufficient hydrolysis of the acid anhydride, and reducing the stability of cellulose acylate. This is preferable because there is no inconvenience. Moreover, it is preferable that the addition time of the reaction terminator is 3 hours or less because problems such as industrial productivity decrease do not occur. The addition time of the reaction terminator is preferably 4 minutes to 2 hours, more preferably 5 minutes to 1 hour, and particularly preferably 10 minutes to 45 minutes. When adding the reaction terminator, the reaction vessel may or may not be cooled, but for the purpose of suppressing depolymerization, it is preferable to cool the reaction vessel to suppress the temperature rise. It is also preferable to cool the reaction terminator.

(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 (eg, tetramethylammonium, tetraethylammonium, tetrabutylammonium, diisopropyldiethylammonium, etc.), alkali metals (preferably lithium, sodium, potassium, rubidium, cesium) More preferably lithium, sodium, potassium, particularly preferably sodium, potassium), group 2 elements (preferably beryllium, calcium, magnesium, strontium, barium, beryllium, calcium, magnesium, particularly preferably calcium, Magnesium), Group 3-12 metals (eg, iron, chromium, nickel, copper, lead, zinc, molybdenum, niobium, titanium, etc.) or Group 13-15 elements (eg, aluminum) Carbonates, bicarbonates, organic acid salts (eg acetate, propionate, butyrate, benzoate, phthalate, hydrogen phthalate, citrate, tartaric acid) Salt), phosphates, hydroxides or oxides. These neutralizing agents may be used in combination, and may form mixed salts (for example, magnesium acetate propionate, potassium sodium tartrate, etc.). Moreover, when the anion of these neutralizing agents is divalent or higher, a hydrogen salt (for example, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium dihydrogen phosphate, magnesium hydrogen phosphate, etc.) may be formed.
More preferably, the neutralizing agent is ammonium, alkali metal, group 2 element or group 13 element, such as carbonate, bicarbonate, organic acid salt, hydroxide or oxide, particularly preferably sodium, potassium. Magnesium, calcium, carbonate, bicarbonate, acetate or hydroxide.
As a solvent for the neutralizer, water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.), organic acid (eg, acetic acid, propionic acid, butyric acid, etc.), ketone (eg, acetone, ethyl methyl ketone, etc.), Preferable examples include polar solvents such as dimethyl sulfoxide and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate thus obtained has an acyl substitution degree close to 3, but for the purpose of obtaining a desired substitution degree, a small amount of catalyst (generally, acylation of remaining sulfuric acid or the like) (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. Since the cellulose sulfate ester is also hydrolyzed during the partial hydrolysis, the amount of sulfate ester bound to the cellulose can be reduced by adjusting the hydrolysis conditions.

(Stop partial hydrolysis)
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. .
When sulfuric acid is used as the catalyst, the amount of the neutralizing agent added to the reaction mixture is preferably an excess equivalent to the sulfate radical (free sulfuric acid, bound sulfuric acid of cellulose). In the present invention, the neutralizing agent can be added in divided portions. However, after the partial hydrolysis (ripening) is completed, the neutralizing agent may be added in an excess equivalent to the sulfate radical. preferable. Sulfuric acid (cellulose sulfate) bonded to cellulose is a monovalent acid, but the equivalent of the neutralizing agent is calculated in terms of free sulfuric acid. Thereby, the equivalent of the neutralizing agent can be determined from the amount of added sulfuric acid. The preferable addition amount of the neutralizing agent is preferably 1.2 to 50 equivalents, more preferably 1.3 to 20 equivalents, and particularly preferably 1.5 to 10 equivalents with respect to the sulfate radical.
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 cellulose is effectively removed. It is also preferable to remove.

(Post-heating process)
It is preferable to hold the reaction mixture after the partial hydrolysis is stopped at 30 ° C. to 100 ° C. for at least 1 hour (post heating step). By carrying out this step, it is possible to reduce the amount of bound sulfuric acid of the cellulose acylate and obtain a cellulose acylate having good thermal stability.
In the post-heating step, the temperature to be held is preferably 40 ° C to 100 ° C, more preferably 50 ° C to 90 ° C, and particularly preferably 60 ° C to 80 ° C. If the temperature is less than 30 ° C, the effect of reducing the amount of bound sulfuric acid is not sufficient, and if it exceeds 100 ° C, it becomes difficult in terms of operability and safety. Further, the holding time in the post-heating step is preferably 1 hour to 100 hours, more preferably 2 hours to 100 hours, and particularly preferably 2 hours to 50 hours. If it is less than 1 hour, the effect of reducing the amount of bound sulfuric acid is not sufficient, and if it exceeds 100 hours, there may be a problem in terms of industrial productivity. In the post-heating step, the reaction mixture is preferably stirred. Further, a neutralizing agent may be additionally added during the post-heating step.

(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, butyric acid, etc.), or the poor solvent is added to the cellulose acylate solution. By mixing, cellulose acylate is re-precipitated, and the desired cellulose acylate can be obtained by washing and stabilization treatment. Reprecipitation may be carried out continuously or batchwise by a fixed amount. It is also preferable to control the form and molecular weight distribution of the re-precipitated cellulose acylate by adjusting the concentration of the cellulose acylate solution and the composition of the poor solvent according to the substitution mode of the cellulose acylate or the degree of polymerization.
In addition, cellulose acylate that has been reprecipitated for the purpose of purification of cellulose acylate by a production method other than the present invention, improvement of the purification effect of cellulose acylate by the production method of the present invention, adjustment of molecular weight distribution and apparent density, etc. Is dissolved again in a good solvent (for example, acetic acid or acetone), the above-mentioned filtration is performed, and a poor solvent (for example, water, carboxylic acid (for example, acetic acid, propionic acid, butyric acid), etc.) acts on this. The operation of performing re-precipitation by allowing them to be performed may be performed once or multiple times as necessary. In addition, the solvent and the poor solvent used at this time are preferably filtered in advance to remove contained fine foreign matters.

(Washing)
The produced cellulose acylate is preferably washed. The washing solvent may be any solvent as long as it has low cellulose acylate solubility and can remove impurities, but usually washing water such as water or warm water is used. The temperature of the washing water is preferably 20 ° C to 100 ° C, more preferably 30 ° C to 95 ° C, and particularly preferably 40 ° C to 95 ° C. The temperature at the time of washing may be constant or may be changed in an arbitrary temperature range, but in the present invention, the cellulose acylate is preferably 40 ° C to 95 ° C, more preferably 50 ° C to 95 ° C, It is particularly preferable to include a step of washing at 60 ° C. to 90 ° C., preferably 1 hour to 100 hours, more preferably 2 hours to 50 hours, particularly preferably 3 hours to 10 hours. You may combine washing | cleaning in said 40 degreeC-95 degreeC, and washing | cleaning in temperature ranges other than this.
The washing process may be performed in a so-called batch system in which filtration and replacement with a washing liquid are repeated, or may be carried out using a continuous washing apparatus. It is also preferable to reuse the waste liquid generated in the reprecipitation and washing steps as a poor solvent in the reprecipitation step, or to recover and reuse a solvent such as carboxylic acid by means such as distillation.
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, and atomic absorption spectrum.
By such treatment, the catalyst (sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, zinc chloride, etc.) in the cellulose acylate, neutralizer (for example, calcium, magnesium, iron, Aluminum or zinc carbonates, acetates, hydroxides or oxides), reaction products of neutralizing agents with catalysts, carboxylic acids (eg acetic acid, propionic acid, butyric acid), reactions of neutralizing agents with carboxylic acids Can be removed, which is effective to increase the stability of cellulose acylate.

(Stabilization)
Cellulose acylate after washing with hot water treatment is weakly alkaline (for example, carbonates, bicarbonates such as sodium, potassium, calcium, magnesium, aluminum, etc.) in order to further improve the stability or lower the carboxylic acid odor. It is also preferable to treat with an aqueous solution of hydroxide, oxide, etc.). The stabilizer solution used at this time is preferably filtered to remove the contained fine foreign matters.
The amount of residual impurities is the metal content of the water used (the amount of metal ions contained as a minor component in the water used for the washing water, etc.), the amount of the washing liquid, the washing temperature, the time, the stirring method, the washing container It can be controlled by the form and the composition and concentration of the stabilizer. In the present invention, it is preferable to set conditions for acylation, partial hydrolysis, neutralization and washing so that the amount of residual sulfate radical (as the sulfur atom content) is 50 to 500 ppm. The amount of residual alkali metal and the amount of group 2 elements can be adjusted according to the conditions of partial hydrolysis, neutralization and washing.
In the present invention, the molar content (S) of the residual sulfate radical contained in the cellulose acylate defined by the following formula (A), the alkali metal (potassium, sodium, etc.) and the elements of two groups (magnesium, The ratio (M / S) to the molar content (M) of calcium or the like is preferably 0.5 or more and 2 or less.
Formula (A): M / S = (Mole content of alkali metal / 2 + Mole content of alkaline earth metal) / Mole content of sulfur If cellulose acylate satisfies these relationships, thermal stability is improved. be able to.

(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 method is not particularly limited as long as the desired moisture content can be obtained. However, it is preferable that the drying method be performed efficiently by using means such as heating, air blowing, decompression, and stirring alone or in combination. 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 in the present invention has a moisture content of preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Degree of polymerization)
The degree of polymerization of the cellulose acylate used in the present invention is preferably 80 to 1000, more preferably 100 to 850, still more preferably 120 to 650, and particularly preferably 130 to 450, as the number average degree of polymerization according to the GPC method. is there. At this time, the number average degree of polymerization by the GPC method can be determined by dividing the number average molecular weight by the average molecular weight of the repeating unit.
In addition to the molecular weight distribution measurement by gel permeation chromatography (GPC), the average degree of polymerization is Uda et al. , 1962). These are further described in detail in JP-A-9-95538.
In the present invention, the weight-average polymerization degree / number-average polymerization degree of cellulose acylate is preferably 1.0 to 5, more preferably 1.3 to 4, and preferably 1.5 to 3.5. It is particularly preferred.
Moreover, 15000-300000 are preferable, as for the range of the number average molecular weight of the cellulose acylate used by this invention, 20000-250,000 are more preferable, 25000-200000 are more preferable, and 30000-150,000 are especially preferable.

In the present invention, the average degree of substitution of substituents can be determined by ¹ H-NMR or ¹³ C-NMR.

  In the present invention, two or more different types of cellulose acylates may be mixed or separated into layers.

(Form)
The cellulose acylate composition of the present invention can take various shapes such as particles, powders, fibers, lumps, solutions, melts, and films.
Since the raw material for film production is preferably in the form of particles or powder, the cellulose acylate composition after drying is crushed and sieved in order to make the particle size uniform and improve handling. Also good. When the cellulose acylate composition is in the form of particles, 90% by mass or more of the particles used preferably have a particle size of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle size of 1-4 mm. The cellulose acylate composition particles preferably have a shape as close to a sphere as possible. The cellulose acylate composition of the present invention preferably has an apparent density of 0.5 to 1.3 g / cm ³ , more preferably 0.7 to 1.2 g / cm ³ , and particularly preferably 0.8 to 1. .15 g / cm ³ . The method for measuring the apparent density is defined in JIS K-7365.
The cellulose acylate composition of the present invention preferably has an angle of repose of 10 to 70 degrees, more preferably 15 to 60 degrees, and particularly preferably 20 to 50 degrees.

<High molecular compound having a repeating unit represented by the general formula (1)>
Next, the high molecular compound which has a repeating unit represented by General formula (1) is demonstrated.

[In General Formula (1), X represents a monovalent or condensed polycyclic aliphatic group or aromatic group, and represents a tetravalent linking group having 4 to 30 carbon atoms. Y represents a divalent linking group containing a monocyclic or condensed polycyclic aliphatic group or aromatic group and having 4 to 30 carbon atoms. ]

In general formula (1), X represents a monovalent or condensed polycyclic aliphatic group or aromatic group, and represents a tetravalent linking group having 4 to 30 carbon atoms.
From the viewpoint of the transparency of the cellulose acylate composition of the present invention and the solubility of the compound represented by the general formula (1), the X contains a monocyclic or condensed polycyclic aliphatic group, It is preferable to represent a tetravalent linking group having 4 to 30 carbon atoms.
The X is more preferably a tetravalent linking group containing a monocyclic or condensed polycyclic aliphatic group and comprising 4 to 20 carbon atoms. More preferably, it contains a monovalent aliphatic group and a tetravalent linking group having 5 to 12 carbon atoms or a condensed polycyclic aliphatic group, and has 5 carbon atoms. It is a tetravalent linking group which is ˜16. Particularly preferred is a tetravalent linking group containing a monocyclic aliphatic group and comprising 5 to 9 carbon atoms.
The monocyclic or condensed polycyclic aliphatic group or aromatic group contained in X is preferably benzene, cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, bicyclo [2 2.2], bicyclo [2.2.2] oct-7-ene, trifluoromethylbenzene, di (trifluoromethyl) benzene, biphenyl, dimethylbenzene, bis [3,5-di (trifluoromethyl) Phenoxy] benzene, 3,3 ′, 4,4′-tetracarboxydiphenyl ether, diphenyl ether, benzophenone, naphthalene, diphenylmethane, diphenylsulfone, 2,2-diphenylpropane, 2,2-diphenylhexafluoropropane, 5,5′- Bis (trifluoromethyl) biphenyl, 2,2 ', 5,5'-teto Tetrakis (trifluoromethyl) biphenyl, 5,5'-bis (trifluoromethyl) diphenyl ether, 5,5'-bis (trifluoromethyl) benzophenone.

  Specific examples of X in the form of tetracarboxylic acid include substituted or unsubstituted 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), cyclobutanetetracarboxylic acid, 1,2,4, 5-cyclohexanetetracarboxylic acid, bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid And acid or bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid. From the viewpoint of thermal stability when the resin or film is exposed to high temperature, 1,2,4,5-cyclohexanetetracarboxylic acid, bicyclo [2.2.1] heptane-2,3,5, 6-tetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid, or bicyclo [2.2.2] oct-7-ene-2,3,5,6 Tetracarboxylic acids are preferred, 1,2,4,5-cyclohexanetetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid, or bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic acid is more preferred, and 1,2,4,5-cyclohexanetetracarboxylic acid is particularly preferred.

Examples of other tetracarboxylic acids as carboxylic acid structures include the following. That is, (trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, diphenylpyromellitic acid, dimethylpyromellitic acid, bis [3,5-di (trifluoromethyl) phenoxy] pyromellitic acid, 2 , 3,3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-tetracarboxydiphenyl ether, 2,3 ′, 3, 4'-tetracarboxydiphenyl ether, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-tetracarboxynaphthalene, 1,4,5,8-tetracarboxynaphthalene, 3,3' , 4,4′-tetracarboxydiphenylmethane, 3,3 ′, 4,4′-tetracarboxydiphenylsulfone, 2,2-bis (3,4 Carboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5′-bis (trifluoromethyl) -3,3 ′, 4,4′-tetracarboxybiphenyl, 2 , 2 ′, 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-tetracarboxybiphenyl, 5,5′-bis (trifluoromethyl) -3,3 ′, 4,4 '-Tetracarboxydiphenyl ether, 5,5'-bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybenzophenone, bis [(trifluoromethyl) dicarboxyphenoxy] benzene, bis (dicarboxyphenoxy ) Bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene, 3,4,9, 0-tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane, cyclobutanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis [4- (3,4 -Dicarboxyphenoxy) phenyl] hexafluoropropane, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldisiloxane, difluoropyromellitic acid, 1, 4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene, 1,4-bis (3,4-dicarboxytrifluorophenoxy) octafluorobiphenyl, pyrazine-2,3,5,6-tetracarboxylic Acid, pyrrolidine-2,3,4,5-tetracarboxylic acid, thiophene- 2,3,4,5-tetracarboxylic acid, 9,9-bis (3,4-dicarboxyphenyl) fluorene and the like can be mentioned.
That is, as a specific example of X, a tetravalent group obtained by removing four carboxy groups from the above exemplified tetracarboxylic acid can be mentioned.

In general formula (1), Y represents a divalent linking group containing a monocyclic or condensed polycyclic aliphatic group or aromatic group and having 4 to 30 carbon atoms. That is, Y is a divalent linking group having 4 to 30 carbon atoms and containing a monocyclic or condensed polycyclic aromatic group, or a monocyclic ring having 4 to 30 carbon atoms. Represents a divalent linking group containing a formula or condensed polycyclic aliphatic group.
Y is preferably a carbon that contains an aromatic group and contains a divalent linking group having 6 to 28 carbon atoms, or a monocyclic or condensed polycyclic aliphatic group. A divalent linking group having 4 to 20 atoms. More preferably, it contains an aromatic group and a divalent linking group having 7 to 28 carbon atoms and a monocyclic aliphatic group, and has 2 to 12 carbon atoms. It is a divalent linking group containing a valent linking group or a condensed polycyclic aliphatic group and comprising 7 to 20 carbon atoms. Particularly preferred is a divalent linking group containing an aromatic group and having 12 to 28 carbon atoms.

Examples of the ring structure of the monocyclic or condensed polycyclic aromatic group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, pyrazine ring, benzofuran ring, carbazole ring, etc. A ring and a naphthalene ring are preferable, and a benzene ring is particularly preferable. Examples of the ring structure of the monocyclic or condensed polycyclic aliphatic group include a cyclobutane ring, a cyclohexane ring, a bicycloheptane ring, a bicyclooctane ring, an adamantane ring, a diamantane ring, and a morpholine ring.
Y may be composed of one of the ring structures described above, or may have a plurality of ring structures. When Y has a plurality of ring structures, the plurality of ring structures may be linked by a single bond, or may be linked by a group (carbonyl, methylene, ether, or the like) that links the rings.
The monocyclic or condensed polycyclic aliphatic group or aromatic group contained in Y is preferably benzene, biphenyl, toluene, ditrifluoromethylbenzidine, octafluorobenzidine, 3,3′-dimethylbiphenyl, 3,3′-dimethoxybiphenyl, 3,3′-difluorobiphenyl, 2,2-bis [4-phenoxyphenyl] propane, 2,2-bis [4-phenoxyphenyl] hexafluoropropane, 4,4′- Diphenoxybiphenyl, bis [4-phenoxyphenyl] sulfone, diphenyl ether, bis [4-phenoxyphenyl] ether, 1,4-diphenoxybenzene, 1,3-diphenoxybenzene, 2,2-diphenylpropane, 2,2 -Diphenylhexafluoropropane, benzophenone, etc. .

  From the viewpoint of improving birefringence, it is preferable that Y in the general formula (1) includes a structure represented by the following general formula (2).

In general formula (2), R ¹ independently represents a substituent. The type of the substituent is not particularly limited, but is preferably a halogen atom, an alkyl group, or an aryl group, more preferably a chlorine atom, a bromine atom, a fluorine atom, a methyl group, an ethyl group, a phenyl group, or a naphthyl group. When there are a plurality of R ¹ in the general formula (2), the substituents represented by each R ¹ may be the same or different from each other, and the plurality of substituents are bonded to each other to form a ring. Also good. When the substituents are bonded to form a ring, a 5- to 6-membered ring is preferable, and a 6-membered ring is more preferable.
p represents an integer of 0 to 4, preferably an integer of 2 to 4.
n represents a positive integer, preferably an integer of 1 to 3, and more preferably 1 or 2. When n is 2 or 3, the structures of n phenylene groups may be the same or different, but the same case is preferable.
The connecting position with the main chain in the phenylene group is preferably the 1,3-position or the 1,4-position, more preferably the 1,4-position. When p is 1 to 4, the relationship between the linking position with the main chain and the substitution position of R ¹ is not particularly limited.

  Specific examples of Y represented by the general formula (2) are p-phenylenediamine, benzidine, o-tolidine, m-tolidine, bis (trifluoromethyl) benzidine, octafluorobenzidine, 3 , 3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminobiphenyl, 3,3′-difluoro -4,4'-diaminobiphenyl, m-phenylenediamine, o-phenylenediamine, 3,3'-diamino-biphenyl, etc., and these may be used alone or in combination of two or more.

Further, specific examples of the Y component other than the repeating unit represented by the general formula (2) can be given in the form of a diamine, such as 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2- Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- ( 3-aminophenoxy) phenyl] sulfone, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis (4-aminophenoxy) Benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4 Aminophenyl) hexafluoropropane, 4,4'-diamino benzophenone. You may use these in combination with the repeating unit represented by General formula (2).
That is, as a specific example of Y, a divalent group obtained by removing two amino groups from the exemplified diamine can be given.

The polymer compound (polyimide) containing the repeating unit represented by the general formula (1) can be obtained, for example, from tetracarboxylic acids containing X and diamines containing Y. As a method of obtaining a polyimide from tetracarboxylic acids and diamines, a one-stage polymerization method in which a tetracarboxylic acid anhydride and a diamine are polymerized in a high-temperature organic polar solvent to form a polyimide, and a tetracarboxylic acid is first produced at a low temperature. There is a two-stage polymerization method in which polyamic acid is synthesized from an anhydride and diamine, a dope is formed, and then imidized at a high temperature.
The polymerization temperature in the one-stage polymerization method is usually 100 to 250 ° C., preferably 150 to 200 ° C., and the polymerization time is usually 0.5 hours to 20 hours, preferably 1 to 15 hours. A polyimide can be produced by applying the polymerized solution as it is on a substrate such as a glass plate or a metal plate and evaporating the solvent. If necessary, the polymer solution is reprecipitated in a poor solvent such as methanol or water, then the solid is dissolved in a good solvent, and the solution is applied onto a substrate such as a glass plate or metal plate, and the solvent is evaporated. Can also be manufactured. Moreover, when imidation is inadequate, imidation can be performed and manufactured by heating to the vicinity of the glass transition temperature of a polymer after coating film formation. In the case of the two-stage polymerization method, the polyamic acid synthesis is performed at a temperature of 0 to 120 ° C., preferably 15 to 120 ° C., more preferably 20 ° C. to 110 ° C. for 0.5 to 100 hours, preferably 1 to 70 hours. The solution after polymerization is directly applied onto a substrate such as a glass plate or a metal plate, heated to 200 ° C. to 350 ° C. and imidized to produce polyimide.

  The polymer compound containing the repeating unit represented by the general formula (1) is preferably synthesized by the above-described one-stage polymerization method. Although the said reaction is based also on the kind of tetracarboxylic acid anhydride and diamine to be used, it is preferable that the solute density | concentration in the case of superposition | polymerization is 5-60 mass%, and it is further 5-50 mass% Preferably, it is 10-40 mass%, and it is especially preferable.

Further, when the polymer compound containing the repeating unit represented by the general formula (1) is not obtained in a high molecular weight even by adjusting the polymerization temperature, the polymerization time, and the solute concentration, an additive is added to perform polymerization. Also good.
Examples of the additive include a catalyst (for example, triethylamine and pyridine), an azeotropic agent (for example, toluene and xylene), a condensing agent, and a dehydrating agent (for example, triphenyl phosphite and acetic anhydride). Etc.). The polymer compound containing the repeating unit represented by the general formula (1) in the present invention is preferably produced using triphenyl phosphite and pyridine among the additives.
When a polyimide is synthesized as a polymer compound containing the repeating unit represented by the general formula (1), sublimation purification and recrystallization purification of acid dianhydride and diamine are necessary to increase the molecular weight. When triphenyl phosphite and pyridine are used, a high molecular weight polyimide can be easily obtained even with unpurified monomers. The concentration of the additive is preferably 0.5 to 70 mol%, more preferably 1 to 50 mol%, and particularly preferably 5 to 30 mol% with respect to the monomer.

  The solvent (organic solvent) used when polymerizing the polymer compound containing the repeating unit represented by the general formula (1) can dissolve diamines and tetracarboxylic acids, and the resulting polyamic acid, polyimide, and the like. Any solvent may be used as long as it is a solvent. Specific examples of such a solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, p-chlorophenol, m-cresol and the like. Moreover, if the polymer compound containing the repeating unit represented by the general formula (1) can be dissolved in a low boiling point solvent such as acetone, 2-butanone, tetrahydrofuran, or dichloromethane, the drying time during film formation is shortened. Can be improved. You may use a solvent individually or in mixture of 2 or more types.

In addition, as a polymer compound containing the repeating unit represented by the general formula (1), polyimide and a polyimide precursor (“polyimide precursor” is formed by ring closure by heating or chemical action to form an imide ring. When synthesizing the organic compound, dicarboxylic acids and monoamines can be used in combination for the purpose of adjusting the molecular weight and preventing coloring, and it is particularly preferable to add a dicarboxylic acid anhydride.
The molecular weight of the polymer compound containing the repeating unit represented by the general formula (1) is preferably 2000 to 500,000, more preferably 2000 to 300,000 in terms of weight average molecular weight, and 3000 to 200,000. It is particularly preferred that If the molecular weight of the polymer compound containing the repeating unit represented by the general formula (1) is 2000 or more, it is preferable because the compound is less likely to cry out. On the other hand, if the molecular weight of the polymer compound containing the repeating unit represented by the general formula (1) is 500,000 or less, it is preferable because the molecular weight can be easily controlled for synthesis and a solution having an appropriate viscosity can be easily obtained. The molecular weight of the polymer compound containing the repeating unit represented by the general formula (1) can be determined based on the viscosity of the solution.

  When the polymer compound is a copolymer containing a plurality of types of repeating units represented by the general formula (1), it may be any of a block copolymer, a random copolymer, or a graft copolymer. Although it is good, it is preferably a random copolymer.

  Although the preferable specific example (Exemplary compound P-1 to P-19) of the high molecular compound containing the repeating unit represented by the said General formula (1) below is given, this invention is not limited to this. In the exemplary compounds, “a” and “b” represent arbitrary molar ratios of the respective structural units, and the exemplary compounds may be block copolymers or random copolymers.

<Cellulose acylate dope composition>
The cellulose acylate dope composition of the present invention contains a polymer compound having a repeating unit represented by the general formula (1) and cellulose acylate. In the cellulose acylate dope composition of the present invention, the mass ratio of the polymer compound containing the repeating unit represented by the general formula (1) and the cellulose acylate is 0.001: 1 to 1: 1. It is preferable. More preferably, it is 0.005: 1 to 0.4: 1, and particularly preferably 0.01: 1 to 0.3: 1.
If the polymer compound containing the repeating unit represented by the general formula (1) is contained at a mass ratio of 0.001: 1 or more with respect to cellulose acylate, the effects of the present invention can be sufficiently exhibited. Is preferable. Moreover, if the polymer compound is contained in a mass ratio of 1: 1 or less with respect to cellulose acylate, the compatibility is good, the phase separation of the dope composition, the whitening of the film, the crying, the deterioration of the surface condition It is preferable because such a failure is unlikely to occur.

(Dope solvent)
As the solvent for the cellulose acylate dope composition of the present invention, any solvent may be used as long as it is highly soluble in the cellulose acylate and the polymer compound containing the repeating unit represented by the general formula (1).
Preferable examples include carboxylic acid (formic acid, acetic acid, propionic acid, butyric acid, etc.), ketone (acetone, ethyl methyl ketone, ethyl isobutyl ketone, etc.), ester (methyl acetate, ethyl acetate, butyl acetate, isopropyl acetate, etc.), halogen Examples of the solvent include dichloromethane, chloroform, dichloroethane and the like. Moreover, as a preferable poor solvent used for reprecipitation, water, alcohol (methanol, ethanol, isopropyl alcohol, butanol, etc.), and hydrocarbon solvents (pentane, hexane, heptane, toluene, etc.) can be mentioned. Moreover, the mixture containing these or a mixture with a poor solvent can also be used.
More preferably, the solvent is a carboxylic acid (such as acetic acid, propionic acid, butyric acid) or a ketone (such as acetone, ethyl methyl ketone, ethyl isobutyl ketone), and particularly preferably a carboxylic acid (such as acetic acid or propionic acid), a ketone ( Acetone). As the poor solvent, water and alcohol (methanol, ethanol, isopropyl alcohol and the like) are more preferable, and water and alcohol (methanol and the like) are particularly preferable.
In the cellulose acylate dope composition of the present invention, the content of components excluding the solvent is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and particularly preferably 8 to 28% by mass in the composition.

  There is no particular limitation on the dissolution order of the cellulose acylate and the polymer compound containing the repeating unit represented by the general formula (1) when preparing the cellulose acylate dope composition of the present invention, and any method can be used. May be. For example, it may be dissolved simultaneously with cellulose acylate. Further, the polymer compound containing the repeating unit represented by the general formula (1) is added to and dissolved in the cellulose acylate solution sequentially, or the repeating unit represented by the general formula (1) is contained. Cellulose acylate may be added to and dissolved in the polymer compound solution. Moreover, after preparing each the solution of a cellulose acylate solution and the high molecular compound containing the repeating unit represented by the said General formula (1), you may mix both.

(Dope filtration)
The dope composition of the present invention may be filtered for the purpose of further removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in cellulose acylate. The retained particle diameter of the filter used for filtration is preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and particularly preferably 2 μm or more and 20 μm or less. When the retained particle diameter of the filter is smaller than 0.1 μm, the filtration pressure is remarkably increased, and industrial production is substantially difficult. On the other hand, if the retained particle diameter is larger than 40 μm, the fine foreign matter cannot be sufficiently removed, and the performance as an optical film becomes insufficient. Further, the filtration is preferably repeated twice or more, and filters having different retained particle diameters may be used in combination. The retained particle diameter can be determined by a method defined in JIS P 3801.

The filter material is not particularly limited as long as it is not adversely affected by the solvent. Preferred examples include a cellulose filter, a metal filter, a ceramic sintered filter, a polytetrafluoroethylene filter (PTFE filter), and a polyethersulfone. A filter, a polypropylene filter, a polyethylene filter, a glass fiber filter, etc. can be mentioned, You may use combining these.
As a filter material, a filter having a charge capturing function can also be preferably used. The filter having a charge trapping function is a filter having a function of electrically trapping and removing charged foreign substances, and usually a filter medium having a charge added thereto. As examples of such a filter, those described in JP-T-4-504379, JP-A 2000-212226, and the like can be selected.
Further, as a filter aid, a method of performing so-called cake filtration in which celite, layered clay mineral (preferably talc, mica, kaolinite, more preferably talc) and the like are mixed in a cellulose acylate solution and filtered is also preferable. Can be used.
For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.
Filtration can be selected from pressure filtration, vacuum filtration, atmospheric pressure filtration, etc., but pressure filtration is preferred.

(Amount of foreign matter)
The content of foreign matter having a particle size of 40 μm or more contained in the cellulose acylate dope composition of the present invention is preferably 0.1 pieces / g or less, and 0.05 pieces / g or less. Is more preferable, and 0.01 or less is particularly preferable.
The content of foreign matters can be measured using a microscope and a light scattering fine particle detector. The shape of the foreign material is usually needle-like or granular, but is not limited thereto. In the present invention, the quantification of foreign substances includes not only unreacted cellulose, but also impurities mixed from the outside, as well as all substances that are not compatible with cellulose acylate, such as gelled products and side reaction products.

[Additive]
In the cellulose acylate composition of the present invention, in addition to the polymer compound having the repeating unit represented by the general formula (1), various additives (for example, an ultraviolet ray inhibitor, a plasticizer, and a deterioration inhibitor) , Fine particles, optical property adjusting agents, and the like).
The polymer compound having the repeating unit represented by the general formula (1) and other additives may be added at any time during the dope preparation process, and as a preparation process at the end of the dope preparation process. These additives may be added.

  These additives may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, an ultraviolet absorber at 20 ° C. or lower and an ultraviolet absorber at 20 ° C. or higher can be mixed and used, and similarly, a plasticizer can be mixed and used. Specifically, the method described in JP 2001-151901 A can be employed.

(UV absorber)
As the ultraviolet absorber, any type can be selected according to the purpose, and an absorber such as a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a benzoate compound, a cyanoacrylate compound, or a nickel complex salt can be used. A benzophenone compound, a benzotriazole compound, and a salicylic acid ester compound are preferable.

  Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert- Butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) ) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like.

  Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate.

  Among these exemplified UV absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2- (2′-hydroxy-3′-tert-butyl) -5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert) -Amylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. The ultraviolet absorbent for liquid crystal is preferably one that is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal and that has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly preferred ultraviolet absorbers are the above-described benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

  As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 These compounds can also be used.

  0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for content of the ultraviolet absorber in the cellulose acylate dope composition of this invention, 0.01-1 mass% is more preferable. If the content is 0.001% by mass or more, the content effect can be sufficiently exerted, and if the content is 5% by mass or less, it is preferable because bleeding out of the ultraviolet absorber to the film surface can be suppressed.

  Further, the ultraviolet absorber may be contained at the same time as dissolving the cellulose acylate, or may be contained in the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because spectral absorption characteristics can be easily adjusted.

(Deterioration inhibitor)
The deterioration inhibitor may be added to prevent cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. A compound such as a UV absorber (JP-A-6-118233) can be used.

(Plasticizer)
The plasticizer is preferably a phosphate ester and / or a carboxylic acid ester. As the phosphate ester plasticizer, for example, triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate and the like are preferable. . Examples of the carboxylate plasticizer include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), O -Triethyl acetyl citrate (OACTE), tributyl O-acetyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, triacetin, tributyrin, butyl phthalyl butyl Glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate and the like are preferable. Furthermore, the plasticizer is preferably (di) pentaerythritol esters, glycerol esters, diglycerol esters.

(Peeling accelerator)
Preferred examples of the peeling accelerator include citric acid ethyl esters.
(Infrared absorber)
As the infrared absorber, for example, those described in JP-A No. 2001-194522 are preferable.

(dye)
In the present invention, a dye for adjusting the hue may be added. The content of the dye is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm in terms of a mass ratio with respect to cellulose acylate. By containing the dye in this way, light piping of the cellulose acylate film can be reduced, and yellowness can be improved. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation. Moreover, you may add to the ultraviolet absorber liquid added in-line. The dyes described in JP-A-5-34858 can be used.

(Matting agent fine particles)
The cellulose acylate dope composition of the present invention may contain fine particles as a matting agent. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. As the fine particles, those containing silicon are more preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / 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.
In the present specification, the primary / secondary particle size refers to the particle size obtained by observing the particles in the film with a scanning electron microscope, and the diameter of a circle circumscribing the particles. Also, 200 particles are observed at different locations, and the average value is 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 (all are trade names, manufactured by Nippon Aerosil Co., Ltd.) are used. can do. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (all of which are trade names, manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and friction while keeping the turbidity of the optical film low. This is particularly preferable because the effect of reducing the coefficient is great.

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a fine particle dispersion. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are stirred and mixed in advance, adding this fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with a main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add fine particles to this and disperse with a disperser. This is used as a fine particle additive solution, and this fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer. There is also a method of mixing. Although the present invention is not limited to these methods, the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. More preferred is mass%. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved.
The content of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

[Manufacturing process of cellulose acylate film]
(Dissolution process)
Preparation of a solution (dope) of a cellulose compound (for example, cellulose acylate) is not particularly limited in its dissolution method, and may be performed at room temperature, and further, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. . For example, regarding the preparation of a cellulose acylate solution, and further the steps of solution concentration and filtration associated with the dissolving step, JIII Journal of Technical Disclosure (Technical No. 2001-1745, pages 22 to 25, March 15, 2001) The production process described in detail in (Issue, Association of Inventions) is preferably used.

  The dope transparency of the cellulose acylate solution is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. It is preferable that various additives are sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the dope transparency, the dope solution is injected into a 1 cm square glass cell, and the absorbance at 550 nm is measured with a spectrophotometer (UV-3150, trade name, manufactured by Shimadzu Corporation). Only the solvent is measured in advance as a blank, and the transparency of the cellulose acylate solution is calculated from the ratio with the absorbance of the blank.

(Casting, drying, winding process)
Next, a method for producing a film using a solution of a cellulose compound (for example, cellulose acylate) will be described. As a method and equipment for producing a cellulose acylate film, for example, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be widely adopted. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of revolutions, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as web) is peeled from the metal support at the peeling point where the metal support is uniformly cast on the metal support, and the metal support has almost gone around. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder. Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film and the silver halide photographic light-sensitive material which are optical members for electronic displays, which is the main use of the cellulose acylate film, in addition to the solution casting film forming apparatus In many cases, a coating apparatus is added for surface processing on a film such as an undercoat layer, an antistatic layer, an antihalation layer, or a protective layer. These are described in detail in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, pages 25-30, published on March 15, 2001, Japan Institute of Invention), and include casting (including co-casting). ), Metal support, drying, peeling, etc., and can be preferably used in the present invention.

(Extension process)
The cellulose acylate film of the present invention preferably has a retardation value adjusted by a stretching process. In particular, when the in-plane retardation value of the cellulose acylate film is set to a high value, a method of positively stretching in the width direction, for example, JP-A-62-115035, JP-A-4-152125, A method for stretching the produced film described in JP-A-4-284111, JP-A-4-298310, and JP-A-11-48271 can be used.

  The film is stretched at room temperature or under heating conditions. The heating temperature is preferably not higher than the glass transition temperature of the film. The stretching of the film may be uniaxial stretching only in the longitudinal or lateral direction, or may be simultaneous or sequential biaxial stretching. The film is preferably stretched by 0.1 to 500%, more preferably stretched by 1 to 200%, and further preferably stretched by 1 to 100%.

  In order to suppress light leakage when the polarizing plate is viewed obliquely, it is necessary to arrange the transmission axis of the polarizing film and the slow axis in the plane of the cellulose acylate film in parallel. Since the transmission axis of the roll film-like polarizing film produced continuously is generally parallel to the width direction of the roll film, it is composed of the roll film-like polarizing film and the roll film-like cellulose acylate film. In order to continuously bond the protective film, the in-plane slow axis of the roll film-shaped protective film needs to be parallel to the width direction of the film. Therefore, it is preferable to stretch more in the width direction. The stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched. In the former case, stretching may be performed in a state containing a residual solvent, and the stretching can be preferably performed at a residual solvent amount of 2 to 30% by mass.

  The thickness of the cellulose acylate film of the present invention obtained after drying varies depending on the purpose of use, is preferably in the range of 5 to 500 μm, more preferably in the range of 20 to 300 μm, and in the range of 30 to 150 μm. More preferably. Moreover, it is preferable that it is 40-110 micrometers for optical use, especially for VA liquid crystal display devices. The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

  The width of the cellulose acylate film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, it is preferable to give knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

[Retardation]
First, each retardation in the present invention will be described. In this specification, Re and Rth (unit: nm) are determined according to the following method. First, the film was conditioned for 24 hours at 25 ° C. and 60% relative humidity, and then a prism coupler (MODEL2010 Prism Coupler, trade name, manufactured by Metricon) was used, and a solid laser of 532 nm was used at 25 ° C. and 60% relative humidity. Then, an average refractive index (n) represented by the following formula (a) is obtained.
Formula (a): n = (n _TE × 2 + n _TM ) / 3
[ _Where n _TE is a refractive index measured with polarized light in the film plane direction, and n _TM is a refractive index measured with polarized light in the film surface normal direction. ]

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the film normal direction in KOBRA 21ADH or WR (trade name, manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotary axis) (if there is no slow axis, any in-plane film In total, measurement is performed at 11 points by injecting light of wavelength λ nm from each inclined direction in steps of −50 ° to + 50 ° from the normal direction to the normal direction of the film (with the direction of the rotation axis as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value.
In the above, there is no description regarding λ, and when only Re and Rth are described, it represents a value measured using light having a wavelength of 590 nm. In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. Is calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (b) and (c).

  In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. d represents the film thickness of the film.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is -50 ° to + 50 ° with respect to the normal direction of the film, with Re (λ) being an in-plane slow axis (determined by KOBRA 21ADH or WR) as an inclination axis (rotation axis). The light is incident at a wavelength of λ nm in 10 degree steps and measured at 11 points. Based on the measured retardation value, average refractive index, and input film thickness value, KOBRA 21ADH or WR Calculated.
By inputting these average refractive index and film thickness, nx, ny, and nz are calculated in KOBRA 21ADH or WR. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  The variation in Re (590) value in the width direction of the film is preferably ± 5 nm, more preferably ± 3 nm. Further, the variation in the Rth (590) value in the width direction is preferably ± 10 nm, and more preferably ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

Re (λ) value and Rth (λ) value satisfy the following formulas (I) and (II), respectively, in order to widen the viewing angle of liquid crystal display devices, particularly VA mode and OCB mode liquid crystal display devices. Is preferable. In particular, a cellulose acylate film is preferable when used for a protective film on the liquid crystal cell side of the polarizing plate.
Formula (I): 0 nm ≦ Re (590) ≦ 200 nm
Formula (II): 0 nm ≦ Rth (590) ≦ 400 nm
(In the formula, Re (590) and Rth (590) are values (unit: nm) at the wavelength λ = 590 nm.)
Furthermore, it is more preferable to satisfy the following mathematical formulas (Ia) and (II-a).
Formula (I-a): 30 nm ≦ Re (590) ≦ 150 nm
Formula (II-a): 30 nm ≦ Rth (590) ≦ 300 nm

When the cellulose acylate film of the present invention is used in the VA mode and the OCB mode, it is used only on either one of the upper and lower sides of the cell, in which two sheets are used on both sides of the cell in total (two-sheet type). There are two types of forms (single sheet type).
In the case of the two-sheet type, Re (590) is preferably 20 to 100 nm, and more preferably 30 to 70 nm. Rth (590) is preferably from 70 to 300 nm, more preferably from 100 to 200 nm.
In the case of a single sheet type, Re (590) is preferably 30 to 150 nm, and more preferably 40 to 100 nm. Rth (590) is preferably from 100 to 300 nm, more preferably from 150 to 250 nm.

[Haze]
The cellulose acylate film of the present invention preferably has a value measured using, for example, a haze meter (1001DP type, trade name, manufactured by Nippon Denshoku Industries Co., Ltd.) of 0.1 or more and 0.8 or less. It is more preferably 0.1 or more and 0.7 or less, and particularly preferably 0.1 or more and 0.60 or less. By controlling the haze within the above range, a high contrast image can be obtained when incorporated in a liquid crystal display device as an optical compensation sheet.

[Photoelastic coefficient]
The cellulose acylate film of the present invention is preferably used as a polarizing plate protective film or a retardation plate. When used as a polarizing plate protective film or a retardation plate, the birefringence (Re, Rth) may change due to the stress due to expansion and contraction due to moisture absorption. Such a change in birefringence due to the stress can be measured as a photoelastic coefficient, and the range is preferably 5 × 10 ⁻⁷ (cm ² / kgf) to 30 × 10 ⁻⁷ (cm ² / kgf). More preferably, it is preferably 10 × 10 ⁻⁷ (cm ² / kgf) to 25 × 10 ⁻⁷ (cm ² / kgf), and 7 × 10 ⁻⁷ (cm ² / kgf) to 20 × 10 ⁻⁷ (cm ² / kgf). It is particularly preferred.

[surface treatment]
The cellulose acylate film that has not been stretched or has been stretched is optionally subjected to surface treatment to achieve improved adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer). Can do. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). 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, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the immersion method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 minutes to 10 minutes, followed by neutralization, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during the alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or acid, and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP 2002-82226 A and WO 02/46809 pamphlet.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. The details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<Combination with functional layer>
The cellulose acylate film of the present invention is combined with the functional layer described in detail on pages 32 to 45 of the Japan Society for Invention and Technology (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Invention). It is preferable. Among these, application of a polarizing film (formation of a polarizing plate), application of an optical compensation layer (formation of an optical compensation sheet), and provision of an antireflection layer (formation of an antireflection film) are preferred.

[Polarizing film]
(Polarized film material)
At present, commercially available polarizing films are generally made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used.
The iodine and the dichroic dye in the polarizing film develop 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 (for example, sulfo, amino, hydroxyl). For example, the compounds described in page 58 of the Japan Society for Invention Disclosure Technique (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society for Invention) are mentioned.

  As the binder of the polarizing 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 binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer.

Of these, 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 preferable. Further preferred. 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%, more preferably 80 to 100%.
It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.
The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), more preferably 25 μm or less, and particularly preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.

  Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(Stretching of polarizing film)
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement by the wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. The stretching ratio here represents (length of polarizing film after stretching / length of polarizing film before stretching). Stretching may be performed in parallel to the MD direction (parallel stretching) or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. More preferred is oblique stretching in which the film is stretched with an inclination of 10 to 80 degrees in the oblique direction.

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is usually 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of usually 15 to 50 ° C., preferably 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be performed by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip rolls to be higher than that of the preceding nip rolls. The stretching ratio (after stretching / the length ratio in the initial state: the same hereinafter) is 1.2 to 3.5 times, more preferably 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. Then, it is made to dry at 50 to 90 degreeC, and a polarizing film is obtained.

(B) Diagonal Stretching Method The oblique stretching method can be carried out by stretching using a tenter extending in the tilting direction, as described in JP-A-2002-86554. Since this stretching is carried out in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The relative humidity is preferably 50% to 100%, more preferably 70% to 100%, and particularly preferably 80% to 100%. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.

After the end of stretching, the film is preferably dried at 50 to 100 ° C., more preferably 60 to 90 ° C., preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and particularly preferably substantially 45 ° (40 ° to 50 °).

(Lamination)
The saponified cellulose acylate film and a polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably such that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive for bonding is not particularly limited, but 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.

  The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and particularly preferably in the range of 40 to 50% in the light with a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and particularly preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce a circularly polarizing plate. In this case, lamination is performed so that the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate are 45 degrees. At this time, the λ / 4 plate is not particularly limited, but more preferably has a wavelength dependency such that the retardation becomes smaller as the wavelength becomes lower. 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.

[Addition of optical compensation layer (creation of optical compensation sheet)]
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 cellulose acylate film, and further provides an optically anisotropic layer. It is formed by doing.

(Alignment film)
An alignment film is provided on the surface-treated cellulose acylate film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film plays the role and is not necessarily an essential component. That is, it is possible to produce a polarizing plate using the cellulose acylate film 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 polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett 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 crosslinkability has a function of bonding side chains having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a 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-methylolacrylamide) described in paragraph [0022] of JP-A-8-338913, for example. ), Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, 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 particularly 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%, 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 Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy groups, dialkoxy groups, monoalkoxy groups), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426, for example. Etc.

  When the side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer or the crosslinkable functional group is introduced into the side chain having the function of aligning liquid crystal molecules, the alignment film polymer and optical anisotropy are obtained. The polyfunctional monomer contained in the 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 sheet 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. Specific examples include those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216. 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] of JP-A No. 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 generation of reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer on the transparent support containing the alignment film forming material and the crosslinking agent, followed by drying by heating (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. Heat drying can be normally performed at 20 degreeC-110 degreeC. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is more preferable. The drying time can usually be 1 minute to 36 hours, but is preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is usually 4.5 to 5.5, and 5 is particularly preferable.

The alignment film is provided on the transparent support or 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 step performed when manufacturing a liquid crystal display device can be applied. That is, a method of obtaining alignment by rubbing the surface of the alignment 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 for 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.

(Optically anisotropic layer)
Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer, 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.

1) Rod-like liquid crystalline molecules As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid 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, the polymerizable group and the polymerization described in paragraphs [0064] to [0086] of JP-A-2002-62427 are exemplified. Liquid crystal compounds.

2) Discotic liquid crystalline molecules Discotic liquid crystalline molecules include C. Destrade et al., Mol. Cryst., 71, 111 (1981), benzene derivatives described in C. Destrade et al., Mol. Cryst., 122, 141 (1985), Physics lett, A, 78, 82 (1990).
Truxene derivatives, B. Kohne et al., Angew. Chem., 96, 70 (1984), and JMLehn et al. Chem. Commun., P. 1794 (1985), J. Zhang et al. Am. Chem. Soc., 116, 2655 (1994), and azacrown and phenylacetylene 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] of JP-A No. 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 the discotic liquid crystalline molecules or the material of the alignment film, or by selecting the rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

(Other composition of optically anisotropic layer)
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, 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 liquid crystal molecules have compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or do 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 the thing which shows copolymerizability with respect to the liquid crystal compound which has said polymeric group is preferable. Examples thereof include those described in paragraph numbers [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1% by mass to 50% by mass and preferably in the range of 5% by mass 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] of JP-A No. 2001-330725.

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

  Examples of the polymer include cellulose acylate. Preferable examples of cellulose acylate 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% by mass to 10% by mass with respect to the liquid crystalline molecule so as not to inhibit the alignment of the liquid crystal molecules. It is more preferable that it is in the range.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Formation of optically anisotropic layer)
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

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

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

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448,828). Description), α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758). ), 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.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, and particularly preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

(Combination with polarizing film)
It is also preferable to combine this optical compensation sheet 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 created. . When a polarizing plate using the cellulose acylate film of 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 of the polarizing film and the optical compensation layer may be 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. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the LCD.

[Addition of antireflection layer (production of antireflection film)]
The antireflection film generally has 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) as a transparent support. It is provided above.
As a method of forming a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes are laminated, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or a sol-gel method of a metal compound such as a metal alkoxide. Examples thereof include a method of forming a thin film by forming a colloidal metal oxide particle film after post-treatment (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310).

On the other hand, various antireflection films in which thin films are laminated by applying a dispersion in which inorganic particles are dispersed in a matrix have been proposed as antireflection films having high productivity. Examples of the antireflection film by application include an antireflection film in which a layer provided with an antiglare property having fine irregularities on the surface is formed on the uppermost layer.
The cellulose acylate film of the present invention can be applied to the antireflection film produced by any of the above methods, but is particularly preferably applied to the antireflection film produced by a coating method (coating type).

(Layer structure of coating type antireflection film)
An antireflection film consisting of a layer structure in which at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) are sequentially formed on a transparent support is designed so that the refractive index satisfies the following relationship: The
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. May be. Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. Examples thereof include those described in 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 etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, and more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and particularly 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 inorganic compounds 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, a technique for treating the surface of the particles with a surface treatment agent (for example, described in JP-A Nos. 11-295503, 11-153703, and 2000-9908). Technology that treats with a silane coupling agent, technology that treats with an anionic compound or organometallic coupling agent described in JP 2001-310432 A, etc., technology that makes a core-shell structure with high refractive index particles as a core (For example, a technique described in JP-A-2001-166104), a technique using a specific dispersant (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002) Technology described in Japanese Patent Application Publication No. 2776069, etc. can be used. Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

Further, the composition is selected from a composition containing a polyfunctional compound having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound having a hydrolyzable group, and a composition of a partial condensate thereof. At least one composition is preferred. Examples of the compounds used in these compositions 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, a curable film described in JP 2001-293818 A can be exemplified.

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 refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(Low refractive index layer)
The low refractive index layer is a layer formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is generally 1.20 to 1.55. Preferably it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. In order to greatly improve the scratch resistance, it is effective to impart slipperiness to the surface. Specifically, a conventionally known method for forming a thin film layer in which a silicone compound or a fluorine-containing compound is introduced can be applied. .

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. Moreover, it is preferable that a fluorine-containing compound is a compound containing the crosslinkable or polymerizable functional group which contains a fluorine atom in 35-80 mass%.

For example, paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and paragraph number [0027] of JP-A-2001-40284. To [0028], and compounds described in JP-A No. 2000-284102.
The silicone compound is a compound having a polysiloxane structure, and preferably has a curable functional group or a polymerizable functional group in the polymer chain and forms a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (trade name, manufactured by Chisso Corporation)), polysiloxane having silanol groups at both ends (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 by light irradiation at the same time as or after coating the coating composition for forming the outermost layer containing a polymerization initiator or a sensitizer. It is preferable to carry out by heating.
Also preferred is a sol-gel cured film obtained by curing an organometallic compound such as a silane coupling agent and a silane coupling agent having a specific fluorine-containing hydrocarbon group by 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 and the like), silyl compounds containing a poly (perfluoroalkyl ether) group which is a fluorine-containing long chain group (Japanese Patent Laid-Open Nos. 2000-117902, 2001-48590, 2002) And the like described in JP-A-53804).

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 particularly preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer can be provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index 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 organometallic compound having a hydrolyzable functional group 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 in the description of 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 particularly preferably 3H or more in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount 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. The technique described in -107512 gazette etc. can be used.

(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.

(Application method)
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or 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 retained. 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 to.

<Liquid crystal display device>
The cellulose acylate film of the present invention, the polarizing plate using the cellulose acylate film, the retardation film and the optical film can each be preferably incorporated in a liquid crystal display device. Liquid crystal display devices include TN (Twisted Nematic) type, IPS (In-Plane Switching) type, FLC (Ferroelectric Liquid Crystal) type, AFLC (Anti-ferroelectric Liquid Crystal) type, OCB (Optically Compensatory Bend) type, STN ( Examples include super twisted nematic (ECB) type, ECB (electrically controlled birefringence) type, VA (vertically aligned) type, and HAN (hybrid aligned nematic) type display devices. Further, the cellulose acylate film of the present invention can be preferably used in any of transmissive, reflective, and transflective liquid crystal display devices. Each liquid crystal mode will be described below.

(TN type liquid crystal display device)
The cellulose acylate film of the present invention may be used as a support for an optical compensation sheet of a TN type liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation sheet used in the TN type liquid crystal display device can be produced according to the descriptions in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. it can. In addition, the papers of Mori et al. (Jpn. J. Appl. Phys., Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys., Vol. 36 (1997) p. 1068). It can be made according to the description.

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

(VA type liquid crystal display device)
The cellulose acylate film of the present invention is particularly advantageously used as a support for an optical compensation sheet of a VA liquid crystal display device having a VA mode liquid crystal cell. The Re value of the optical compensation sheet used in the VA liquid crystal display device is preferably 0 to 150 nm and the Rth value is preferably 70 to 400 nm. When two optically anisotropic polymer films are used for the VA liquid crystal display device, the Rth value of the film is preferably 70 to 250 nm. When one optically anisotropic polymer film is used for the VA liquid crystal display device, the Rth value of the film is preferably 150 to 400 nm. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS liquid crystal display device, ECB liquid crystal display device)
The cellulose acylate film of the present invention is also suitably used as an optical compensation sheet for an IPS liquid crystal display device or ECB liquid crystal display device having an IPS mode or ECB mode liquid crystal cell, or as a protective film for a polarizing plate. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the cellulose acylate film of the present invention contributes to improving the color tone, widening the viewing angle, and improving the contrast. In this aspect, the cellulose acylate film of the present invention is used for the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate among the protective films of the polarizing plates above and below the liquid crystal cell. It is preferable to use the polarizing plate at least on one side. More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is not more than twice the value of Δn · d of the liquid crystal layer. It is preferable to set to.

(OCB type liquid crystal display device, HAN type liquid crystal display device)
The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation sheet of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In the optical compensation sheet used for the OCB type liquid crystal display device or the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of the retardation value is minimum does not exist in the plane of the optical compensation sheet or in the normal direction. The optical properties of the optical compensation sheet used in the OCB type liquid crystal display device or the HAN type liquid crystal display device are also the optical properties of the optical anisotropic layer, the optical properties of the support, and the optical anisotropic layer and the support. Is determined by the arrangement of An optical compensation sheet used for an OCB type liquid crystal display device or a HAN type liquid crystal display device can be produced according to the description in JP-A-9-197397. It can also be prepared according to the description of Mori et al. (Jpn. J. Appl. Phys., Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The cellulose acylate film of the present invention is also advantageously used as an optical compensation sheet for TN-type, STN-type, HAN-type, and GH (Guest-Host) -type reflective liquid crystal display devices. These display modes have been well known since ancient times. The TN-type reflective liquid crystal display device can be manufactured according to the descriptions in JP-A-10-123478, International Publication WO98 / 48320, and Japanese Patent No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device can be produced according to the description in the pamphlet of International Publication WO00 / 65384.

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

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. 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 called 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 crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

  According to the present invention, a cellulose acylate having high birefringence that can be suitably used as an optical film can be obtained. Furthermore, by using an optical film using the cellulose acylate, a high-quality retardation film, polarizing plate, optical compensation sheet, antireflection film and liquid crystal display device can be obtained. Therefore, the present invention is a useful invention with high industrial applicability.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these.

Synthesis example 1
(Preparation of Exemplified Compound P-15)
In a reaction vessel equipped with a thermometer, a stirrer, and a nitrogen introduction tube, 32.0 parts by mass of 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl was added, and 300 parts by mass of N-methyl-2-pyrrolidone was added. After dissolution, 22.4 parts by weight of 1,2,4,5-cyclohexanetetracarboxylic dianhydride was gradually added at 15 ° C. When the reaction was carried out at 30 ° C. for 1 hour, then at 70 ° C. for 1 hour and further at 100 ° C. for 1 hour, a transparent solution was obtained. Next, 6.2 parts by weight of triphenyl phosphite and 1.6 parts by weight of pyridine were gradually added dropwise as an additive, followed by stirring at 100 ° C. for 0.5 hours, 130 ° C. for 0.5 hours, and 150 ° C. The mixture was stirred at 170 ° C. for 0.5 hour for 5 hours. Thereafter, the solution was allowed to cool, and after allowing to cool, it was reprecipitated in a mixed solution of 2000 parts by mass of methanol and 2000 parts by mass of water, and purified by repeated filtration and washing to obtain the exemplified compound P-15.
Other polymer compounds containing the repeating unit represented by the general formula (1) were similarly prepared.

Example 1
[Preparation of Cellulose Acetate Dope Composition Samples 1-31]
The following components were put into a mixing tank, stirred while heating, mixed with each component, and cellulose acetate dope composition samples 1 to 31 were prepared.
<Cellulose acetate dope composition>
Cellulose acylate (types and amounts listed in Table 1)
Dichloromethane 782 parts by mass Methanol 68 parts by mass A polymer compound containing a repeating unit represented by the general formula (1) (type and amount described in Table 1)

  In Table 1, DSAc represents the degree of substitution of acetyl groups in cellulose acylate, DSPr represents the degree of substitution of propionyl groups in cellulose acylate, and DSBu represents the degree of substitution of butyryl groups in cellulose acylate.

Example 2
[Production of Cellulose Acylate Film Samples 101 to 131]
Cellulose acylate dope composition samples 1-31 prepared in Example 1 were each cast using a band casting machine. Unstretched cellulose acylate film samples 101 to 131 were prepared by adjusting the film thickness to 80 μm without aggressive stretching after casting.

[Production of Cellulose Acylate Film Samples 201-231]
Cellulose acylate dope composition samples 1-31 prepared in Example 1 were each cast using a band casting machine. After casting, a film having a residual solvent amount of 15% by mass is horizontally stretched at a stretch ratio of 15% using a tenter, and adjusted so that the film thickness is all 80 μm, and a stretched cellulose acylate film sample 201-231 were produced.

[Evaluation]
(Measurement of light transmittance)
For the cellulose acylate film samples 101 to 131 and 201 to 231, each cellulose acylate film was conditioned at 25 ° C. and 60% RH for 24 hours, and then a transparency measuring device (AKA photoelectric tube colorimeter: manufactured by KOTAKI Corporation) was used. The light transmittance was measured using 615 nm visible light.
All of these samples were found to have excellent light transmittance with a light transmittance of 90% or more.

(Measurement of retardation)
A part (120 mm × 120 mm) of each film sample obtained above was taken out, placed in a condition adjusted to 25 ° C. and relative humidity 60% for 2 hours, and then in the “Retardation” section of this specification. Re and Rth were measured by the procedure described. Specifically, using KOBRA 21ADH (trade name, manufactured by Oji Scientific Instruments), light with a wavelength of 590 nm was incident in the normal direction of the film, and Re and Rth were measured. The results are shown in Tables 2 and 3.

As is clear from the results in Tables 2 and 3, all the samples satisfy the above formulas (I) and (II), but the samples 102 to 120, 122 to 125, 127 to 131, 202 to 220, 222 of the present invention. All of ˜225 and 227 to 231 were found to express a larger Re and / or Rth than the samples 101, 121, 126, 201, 221 and 226 of the comparative example. In particular, the stretched samples 202 to 220, 222 to 225, and 227 to 231 of the present invention all express a larger Re and / or Rth than the stretched samples 201, 221 and 226 of the comparative examples. I found out that
Further, as Y in the repeating unit represented by the general formula (1), the samples 103 and 203 containing the exemplified compound P-15 including the structure represented by the general formula (2), and the general formula ( Comparing Samples 131 and 231 containing Example Compound P-19 not containing the structure represented by 2), Sample 103 containing Example Compound P-15 containing the structure represented by General Formula (2) And 203 were found to express higher Re and / or Rth.

Example 3
[Production and Evaluation of Polarizing Plate]
(1) Saponification of Cellulose Acylate Film Each of the above-described unstretched cellulose acylate film of the present invention and a stretched cellulose acylate film obtained by stretching the cellulose acylate film was saponified by the following method.
A 1.5 mol / L sodium hydroxide aqueous solution was used as the saponification solution. The temperature was adjusted to 60 ° C., 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 bath.

(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 the film was stretched in the longitudinal direction to produce a polarizing film having a thickness of 20 μm.

(3) Bonding and Evaluation Two films were selected from the polarizing film thus obtained and the saponified unstretched and stretched cellulose acylate films. After sandwiching the polarizing film between them, polyvinyl alcohol (PVA ) (PVA-117H, trade name, manufactured by Kuraray Co., Ltd.) A 3% aqueous solution was used as an adhesive and the polarizing axis and the cellulose acylate film were laminated so that the longitudinal direction was 90 °. Among these, an unstretched and stretched cellulose acylate film is attached to a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261 at 25 ° C. and a relative humidity of 60%. Brought into 10% relative humidity. Any of the films using the cellulose acylate film of the present invention had a small change in color tone and good performance with little display unevenness.
In addition, according to Example 1 of Japanese Patent Application Laid-Open No. 2002-86554, a polarizing plate stretched using a tenter so that the stretching axis is inclined at 45 ° is similarly produced using the cellulose acylate film of the present invention. As with the above, good results were obtained.

Example 4
[Production and evaluation of optical compensation sheet]
Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the above-described saponified stretched cellulose acylate film of the present invention was used, and this was used as JP-A-2002-62431. The bend-aligned liquid crystal cell described in Example 9 of the publication was attached at 25 ° C. and 60% relative humidity, and was brought into 25 ° C. and 10% relative humidity. When the cellulose acylate film of the present invention was used, good display performance with little leakage and little change in contrast was obtained.

Furthermore, it replaced with the cellulose acetate film which apply | coated the liquid crystal layer of Example 1 of Unexamined-Japanese-Patent No. 7-333433, changed to the stretched cellulose acylate film of this invention, and produced the optical compensation sheet | seat. In this case as well, a good optical compensation sheet could be produced.
Further, a polarizing plate and a retardation polarizing plate using the cellulose acylate film of the present invention are the liquid crystal display device described in Example 1 of JP-A No. 10-48420 and Example 1 of JP-A No. 9-26572. An optically anisotropic layer containing the discotic liquid crystal molecules described in 1., 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 JP-A-2000 When used in the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A-154261, a good liquid crystal display device with extremely little light leakage was obtained.

Example 5
[Production and Evaluation of Low Reflective Film and Liquid Crystal Display]
According to Example 47 of Invention Association Public Technical Report (Public Technical No. 2001-1745, published on March 15, 2001, Invention Association), a low reflection film was produced using the stretched cellulose acylate film described above. The one using the cellulose acylate film obtained good optical performance.
Further, the low reflection film is formed by using a liquid crystal display device described in Example 1 of JP-A-10-48420, a 20-inch VA liquid crystal display device described in FIGS. A 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of 2000-154261 was evaluated by attaching to the outermost layer of the liquid crystal display device, and a good liquid crystal display device with extremely little leakage was obtained.

Claims (14)

A cellulose acylate composition comprising a polymer compound having a repeating unit represented by the following general formula (1) and cellulose acylate.

[In General Formula (1), X represents a monovalent or condensed polycyclic aliphatic group or aromatic group, and represents a tetravalent linking group having 4 to 30 carbon atoms. Y represents a divalent linking group containing a monocyclic or condensed polycyclic aliphatic group or aromatic group and having 4 to 30 carbon atoms. ] The cellulose acylate composition according to claim 1, wherein Y in the general formula (1) includes a structure represented by the following general formula (2).

[In General Formula (2), R ¹ independently represents a substituent, and when there are a plurality of substituents, each substituent may be the same or different. p represents an integer of 0 to 4, and n represents a positive integer. ]   The cellulose acylate composition according to claim 1 or 2, wherein X in the general formula (1) is a monocyclic or condensed polycyclic aliphatic group.   The cellulose acylate composition according to any one of claims 1 to 3, wherein X in the general formula (1) is a cyclohexane ring.   The cellulose acylate composition according to any one of claims 1 to 4, wherein the cellulose acylate is any one of cellulose acetate, cellulose acetate propionate, or cellulose acetate butyrate.   The mass ratio of the polymer compound having the repeating unit represented by the general formula (1) and the cellulose acylate is 0.001: 1 to 1: 1, The cellulose acylate composition according to any one of the above.   A cellulose acylate dope composition comprising the cellulose acylate composition according to any one of claims 1 to 6. It is an optical film which consists of a cellulose acylate composition of any one of Claims 1-6, Comprising: In-plane retardation (Re) and retardation (Rth) of thickness direction are following numerical formula (I). And a cellulose acylate film represented by (II).
Formula (I): 0 nm ≦ Re (590) ≦ 200 nm
Formula (II): 0 nm ≦ Rth (590) ≦ 400 nm
(In the formula, Re (590) and Rth (590) are values (unit: nm) at the wavelength λ = 590 nm.)   A retardation film using the cellulose acylate film according to claim 8.   A polarizing plate comprising a polarizing film and two protective films sandwiching the polarizing film, wherein at least one of the two protective films is the cellulose acylate film according to claim 8 or the retardation according to claim 9. A polarizing plate characterized by being a film.   An optical compensation sheet comprising an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose acylate film according to claim 8 or the retardation film according to claim 9.   An antireflection film comprising an antireflection layer on the cellulose acylate film according to claim 8 or the retardation film according to claim 9.   A cellulose acylate film according to claim 8, a retardation film according to claim 9, a polarizing plate according to claim 10, an optical compensation sheet according to claim 11, and an antireflection film according to claim 12. A liquid crystal display device using at least one of the above-described liquid crystal display devices.   It prepares using the dope composition of Claim 7, The manufacturing method of the cellulose acylate film characterized by the above-mentioned.