JP2013213106A - Cellulose acylate film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose acylate film having low internal haze, high film contrast, and low humidity change value, a polarizing plate using the cellulose acylate film, and a liquid crystal display device.SOLUTION: A cellulose acylate film includes: a composition containing at least one of cellulose acylates which has an acyl group (substituent A) including an aromatic group, has the total of substitution degrees in the second, third, and sixth places of the acyl group being 0.3-2.0, and satisfies the following formula (I); and 10-800 ppm of a phosphorus compound. In the formula (I): 1≤(DS2+DS3)/DS6≤5, DS2, DS3, and DS6 show a substitution degree of substituent A in each of the second, third, and sixth places of the cellulose acylate.

Description

  The present invention relates to a cellulose acylate film, a polarizing plate using the cellulose acylate film, and a liquid crystal display device.

  Cellulose acylate films are widely used as retardation films and polarizing plate protective films for liquid crystal display devices because of their transparency and toughness. In recent years, liquid crystal display devices of various liquid crystal modes have been developed, and cellulose acylate films with adjusted optical characteristics have been proposed so as to contribute to optical compensation corresponding to each mode.

  For example, Patent Document 1 and Patent Document 2 are IPS type, VA type, and OCB type by adjusting the substitution degree of 2-position, 3-position, and 6-position of an acyl group containing an aromatic group or an aliphatic group. A cellulose acylate film suitable for a liquid crystal display device such as the above has been proposed.

  The cellulose acylate films of Patent Document 1 and Patent Document 2 have the advantage of having desired optical properties, but have a problem of high internal haze and low film contrast.

JP 2009-235374 A JP 2007-264287 A

  An object of the present invention is to solve the above problems, specifically, a cellulose acylate film having a low internal haze, a high film contrast, and a low humidity change value, a polarizing plate using the cellulose acylate film, and It is an object to provide a liquid crystal display device.

（式中、Ｘは、水素原子または置換基を表す。ｎは、０又は１〜５の整数を表す。ｎが２以上の場合、複数のＸは互いに連結して縮合多環を形成してもよい。）
［５］ 前記置換基Ａが、ベンゾイル基である［１］〜［４］のいずれかのセルロースアシレートフィルム。
［６］ 前記セルロースアシレートが、炭素原子数が２〜２０の脂肪族アシル基（置換基Ｂ）をさらに有する［１］〜［５］のいずれかのセルロースアシレートフィルム。
［７］ 前記置換基Ｂが、アセチル基、プロピオニル基、ブタノイル基、ヘキサノイル基から選択される［６］のセルロースアシレートフィルム。
［８］ さらに、下記一般式（Ｅ−１）で表される添加剤を０．１〜２０質量部含有する［１］〜［７］のいずれかのセルロースアシレートフィルム。

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

（一般式（Ｑ）中、＊側が前記一般式（Ｅ−１）で表される化合物中の複素環に置換しているＮ原子との連結部位である。）
［９］ 湿度３０％における波長５９０ｎｍの面内レターデーションＲｅ（５９０）と、湿度８０％における波長５９０ｎｍの面内レターデーションＲｅ（５９０）との差が、１０ｎｍ以下であり、湿度３０％における波長５９０ｎｍの面内レターデーションＲｔｈ（５９０）と、湿度８０％における波長５９０ｎｍの面内レターデーションＲｔｈ（５９０）との差が、１５ｎｍ以下である［１］〜［８］のいずれかのセルロースアシレートフィルム。
［１０］ 膜厚が、２０〜８０μｍである［１］〜［９］のいずれかのセルロースアシレートフィルム。
［１１］ ［１］〜［１０］のいずれかのセルロースアシレートフィルムからなる位相差フィルム。
［１２］ ［１］〜［１０］のいずれかのセルロースアシレートフィルムからなる又は含む光学補償フィルム。
［１３］ ［１］〜［１０］のいずれかのセルロースアシレートフィルムと、反射防止層とを有する反射防止フィルム。
［１４］ 偏光膜と、［１］〜［１０］のいずれかのセルロースアシレートフィルムとを有する偏光板。
［１５］ ［１４］の偏光板を有する液晶表示装置。 The means for solving the problem is the means [1] below, preferably the means [2] to [15] below.
[1] A cellulose acylate having an aromatic group-containing acyl group (substituent A) having a total substitution degree of 2-position, 3-position and 6-position of 0.3 to 2.0 and satisfying the following formula (I) A cellulose acylate film comprising an at least one rate and a phosphorus compound of 10 to 800 ppm, and an internal haze value converted to a film thickness of 60 μm is 0.005 to 0.10.
Formula (I) 1 ≦ (DS2 + DS3) / DS6 ≦ 5
(In the formula, DS2, DS3, and DS6 represent the degrees of substitution of the substituent A at the 2-position, 3-position, and 6-position of cellulose acylate, respectively.)
[2] The cellulose acylate film of [1], wherein the phosphorus compound is selected from a phosphate ester and a salt thereof.
[3] The in-plane retardation Re (590) at a wavelength of 590 nm is 220 to 300 nm, and the retardation Rth (590) in the thickness direction at a wavelength of 590 nm is −30 to 30 nm. Cellulose acylate film.
[4] The cellulose acylate film according to any one of [1] to [3], wherein the substituent A is a substituent represented by the following general formula (I).

(In the formula, X represents a hydrogen atom or a substituent. N represents 0 or an integer of 1 to 5. When n is 2 or more, a plurality of Xs are connected to each other to form a condensed polycycle. May be good.)
[5] The cellulose acylate film according to any one of [1] to [4], wherein the substituent A is a benzoyl group.
[6] The cellulose acylate film according to any one of [1] to [5], wherein the cellulose acylate further has an aliphatic acyl group (substituent B) having 2 to 20 carbon atoms.
[7] The cellulose acylate film according to [6], wherein the substituent B is selected from an acetyl group, a propionyl group, a butanoyl group, and a hexanoyl group.
[8] The cellulose acylate film according to any one of [1] to [7], further containing 0.1 to 20 parts by mass of an additive represented by the following general formula (E-1).

(In General Formula (E-1), Y ¹ represents a methine group or —N═. Ra ³¹ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Rb ³¹ , Rc ³¹ , Rd ³¹ and Re ³¹ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and Q ²¹ represents a single bond, —O—, —S—, or —NRf—. , Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and may be linked to Ra ³¹ to form a ring, and X ³¹ , X ^32, and X ³³ each represent Independently represents a single bond or a divalent linking group, and X ³⁴ represents a linking group selected from the group consisting of a divalent linking group represented by the following general formula (Q).
General formula (Q)

(In General Formula (Q), the * side is a linking site with the N atom substituted on the heterocyclic ring in the compound represented by General Formula (E-1).)
[9] The difference between the in-plane retardation Re (590) at a wavelength of 590 nm at 30% humidity and the in-plane retardation Re (590) at a wavelength of 590 nm at 80% humidity is 10 nm or less, and the wavelength at 30% humidity. The cellulose acylate according to any one of [1] to [8], wherein the difference between the in-plane retardation Rth (590) at 590 nm and the in-plane retardation Rth (590) at a wavelength of 590 nm at a humidity of 80% is 15 nm or less. the film.
[10] The cellulose acylate film according to any one of [1] to [9], wherein the film thickness is 20 to 80 μm.
[11] A retardation film comprising the cellulose acylate film of any one of [1] to [10].
[12] An optical compensation film comprising or including the cellulose acylate film of any one of [1] to [10].
[13] An antireflection film comprising the cellulose acylate film of any one of [1] to [10] and an antireflection layer.
[14] A polarizing plate having a polarizing film and the cellulose acylate film of any one of [1] to [10].
[15] A liquid crystal display device having the polarizing plate of [14].

  According to the present invention, it is possible to provide a cellulose acylate film having a low internal haze, a high film contrast, and a low humidity change value, a polarizing plate and a liquid crystal display device using the cellulose acylate film.

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

Re (λ) and Rth (λ) represent in-plane retardation at wavelength λ and retardation in the thickness direction, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. This measuring method is also partially used for measuring the average tilt angle on the alignment film side of the discotic liquid crystal molecules in the optically anisotropic layer, which will be described later, and the average tilt angle on the opposite side.
Rth (λ) is the film surface when Re (λ) is used and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis) Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction (with any rotation direction as the rotation axis) Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative. The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (B) based on the value, the assumed value of the average refractive index, and the input film thickness value.

なお、上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値を表す。また、式（Ａ）におけるｎｘは、面内における遅相軸方向の屈折率を表し、ｎｙは、面内においてｎｘに直交する方向の屈折率を表し、ｎｚは、ｎｘ及びｎｙに直交する方向の屈折率を表す。ｄは膜厚である。
Ｒｔｈ＝（（ｎｘ＋ｎｙ）／２−ｎｚ）×ｄ・・・・・・・・・・・式（Ｂ）

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index. d is the film thickness.
Rth = ((nx + ny) / 2−nz) × d (Equation (B)

  When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method. Rth (λ) is from −50 ° to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis). Measured at 11 points by making light of wavelength λ nm incident in 10 ° steps up to + 50 °, and based on the measured retardation value, average refractive index assumption value and input film thickness value. KOBRA 21ADH or WR is calculated. In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz. In this specification, when there is no special mention about a measurement wavelength, a measurement wavelength is 590 nm.

[Cellulose acylate film]
The cellulose acylate film of the present invention has at least one cellulose acylate having an acyl group (substituent A) containing an aromatic group and 10 to 800 ppm of a phosphorus compound. The cellulose acylate has a total substitution degree of the 2-position, 3-position and 6-position of the substituent A of 0.3 to 2.0 and satisfies the following formula (I).
Formula (I) 1 ≦ (DS2 + DS3) / DS6 ≦ 5
(In the formula, DS2, DS3, and DS6 represent the degrees of substitution of the substituent A at the 2-position, 3-position, and 6-position of cellulose acylate, respectively.)

The present inventor has the effect of negatively increasing the retardation Rth in the thickness direction when an acyl group containing an aromatic group (substituent A) is present at the 2nd and 3rd positions, and when present at the 6th position, the Rth is decreased. It has the effect of increasing it. On the other hand, regarding the retardation Re in the in-plane direction, it was found that the substituent A existing at the 2nd and 3rd positions has an action of increasing the absolute value when stretched.
As a result of further investigation based on this finding, the present inventor has found that the total substitution degree of the 2-position, 3-position and 6-position of the substituent A is 0.3 to 2.0, and the formula (I) is The inventors have found that using a satisfactory cellulose acylate and further having a phosphorus compound reduces the internal haze and improves the film contrast, and the present invention has been completed. Unexpectedly, the humidity change value can be solved by adding the phosphorus compound to the total substitution degree and substitution ratio of the 2-position, 3-position and 6-position of the aromatic acyl group within the predetermined range. I understood.

In order to set the internal haze value converted to a film thickness of 60 μm to 0.005 to 0.10, (DS2 + DS3) / DS6 is set to 1 to 5, preferably 1.1 to 4.0, 1.5 to 3.0 is more preferable. Moreover, the sum total of the substitution degree of 2-position, 3-position, and 6-position of the substituent A is 0.3 to 2.0, preferably 0.4 to 1.8, and more preferably 0.5 to 1.5. preferable.
In addition, the internal haze value converted into a film thickness of 60 μm is 0.005 to 0.10, preferably 0.005 to 0.05, and more preferably 0.005 to 0.03.
Here, the internal haze value is defined as haze caused by internal scattering.

式中、Ｘは、水素原子または置換基を表す。ｎは、０又は１〜５の整数を表す。ｎが２以上の場合、複数のＸは互いに連結して縮合多環を形成してもよい。 (Acyl group containing aromatic group (Substituent A))
The acyl group (substituent A) containing an aromatic group is a substituent represented by the following general formula (I).

In the formula, X represents a hydrogen atom or a substituent. n represents 0 or an integer of 1 to 5. When n is 2 or more, a plurality of Xs may be connected to each other to form a condensed polycycle.

X represents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom and iodine atom), cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfonamide group, Ureido group, aralkyl group, nitro, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, Aryloxysulfonyl group, alkylsulfonyloxy group, heteroaryl group and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R , -P (-R) (-O-R), _{P (-O-R) 2,} -PH (= O) -R-P (= O) (- R) 2, -PH (= O) -O-R, -P (= O) (- R) (—O—R), —P (═O) (— O—R) ₂ , —O—PH (═O) —R, —O—P (═O) (— R) ₂ —O—PH ( ═O) —O—R, —O—P (═O) (— R) (— O—R), —O—P (═O) (— O—R) ₂ , —NH—PH (═O ) —R, —NH—P (═O) (— R) (— O—R), —NH—P (═O) (— O—R) ₂ , —SiH ₂ —R, —SiH (—R) ) ₂ , —Si (—R) ₃ , —O—SiH ₂ —R, —O—SiH (—R) ₂ and —O—Si (—R) ₃ .
R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 or 2.
As the substituent, a halogen atom, cyano, alkyl group, alkoxy group, aryl group, aryloxy group, acyl group, carbonamido group, sulfonamido group and ureido group are preferable, halogen atom, cyano, alkyl group, alkoxy group, An aryloxy group, an acyl group and a carbonamido group are more preferred, a halogen atom, cyano, an alkyl group, an alkoxy group and an aryloxy group are further preferred, and a halogen atom, an alkyl group and an alkoxy group are particularly preferred.

The alkyl group may have a cyclic structure or a branch. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, hexyl, cyclohexyl, octyl and 2-ethylhexyl.
The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms of the alkoxy group is preferably 1 to 20, more preferably 1 to 12, still more preferably 1 to 6, and particularly preferably 1 to 4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy, ethoxy, 2-methoxyethoxy, 2-methoxy-2-ethoxyethoxy, butyloxy, hexyloxy and octyloxy.

The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryl group include phenyl and naphthyl.
The heteroaryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of heteroaryl groups include pyridine.
The aryloxy group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryloxy group include phenoxy and naphthoxy.
The acyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of acyl groups include formyl, acetyl and benzoyl.
The carbonamide group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the carbonamido group include acetamide and benzamide.
The number of carbon atoms in the sulfonamide group is preferably 1 to 20, and more preferably 1 to 12. Examples of the sulfonamide group include methanesulfonamide, benzenesulfonamide, and p-toluenesulfonamide.
The ureido group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of ureido groups include (unsubstituted) ureido.

The aralkyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of aralkyl groups include benzyl, phenethyl and naphthylmethyl.
The alkoxycarbonyl group preferably has 1 to 20 carbon atoms, more preferably 2 to 12 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl.
The aryloxycarbonyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of the aryloxycarbonyl group include phenoxycarbonyl.
The aralkyloxycarbonyl group preferably has 8 to 20 carbon atoms, and more preferably 8 to 12. Examples of the aralkyloxycarbonyl group include benzyloxycarbonyl.
The carbamoyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the carbamoyl group include (unsubstituted) carbamoyl and N-methylcarbamoyl.
The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of sulfamoyl groups include (unsubstituted) sulfamoyl and N-methylsulfamoyl.
The acyloxy group preferably has 1 to 20 carbon atoms, more preferably 2 to 12 carbon atoms. Examples of the acyloxy group include acetoxy and benzoyloxy.

The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkenyl groups include vinyl, allyl and isopropenyl.
The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkynyl groups include thienyl.
The alkylsulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms.
The arylsulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.
The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms.
The aryloxysulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.
The alkylsulfonyloxy group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms.
The aryloxysulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms.

  Next, in the fatty acid ester residue in the cellulose mixed acid ester, the aliphatic acyl group has 2 to 20 carbon atoms, specifically acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl. , Stearoyl and the like. Acetyl, propionyl and butyryl are preferred, and acetyl is particularly preferred. In the present invention, the aliphatic acyl group is meant to include those having a substituent, and examples of the substituent include those exemplified as X in the general formula (I).

  In the general formula (I), the number (n) of the substituents X substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, particularly preferably 1 or 2. .

Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).
Specific examples of the aromatic acyl group represented by the general formula (I) are as shown below. 1, 3, 5, 6, 8, 18, 28, more preferably 1, 3, and 6.

  Specific examples of the aromatic acyl group represented by the general formula are shown below, but the present invention is not limited thereto.

  Among these, more preferably, the substituent A is a benzoyl group. The substituent A possessed by the cellulose acylate may be one kind or two or more kinds.

The following is an example of the ratio of the substitution degree at the 2nd, 3rd and 6th positions.

Substitution of the aromatic acyl group to the hydroxyl group of cellulose generally includes a method using a symmetric acid anhydride and a mixed acid anhydride derived from an aromatic carboxylic acid claloid or an aromatic carboxylic acid. Particularly preferred is a method using an acid anhydride derived from an aromatic carboxylic acid (described in Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)).
As a method for producing the cellulose mixed acid ester compound used in the present invention as the above method, (1) a method of once producing a cellulose fatty acid monoester or diester and then introducing an aromatic acyl group into the remaining hydroxyl group (2) Examples thereof include a method in which a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid is reacted directly with cellulose.
In the former, the production method of the cellulose fatty acid ester or diester is a well-known method, but the subsequent reaction for introducing an aromatic acyl group into this further varies depending on the type of the aromatic acyl group, but preferably the reaction temperature. The reaction time is 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes.
In the latter method using the mixed acid anhydride, the reaction conditions vary depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 to 300. Minutes, more preferably 60 to 200 minutes. In any of the above reactions, the reaction may be performed in the absence of a solvent or in a solvent, but is preferably performed using a solvent. As the solvent, dichloromethane, chloroform, dioxane and the like can be used.

  The cellulose acylate may further have an acyl group other than an acyl group containing an aromatic group (substituent A), specifically an aliphatic acyl group (substituent B).

The aliphatic acyl group (substituent B) in the present invention may be a linear, branched or cyclic aliphatic acyl group, or may be an aliphatic acyl group containing an unsaturated bond. Good. Preferably it is a C2-C20, More preferably, it is a C2-C10, More preferably, it is a C2-C6 aliphatic acyl group. Preferable examples of the substituent B are an acetyl group, a propionyl group, a butyryl group, and a hexanoyl group, and among them, an acetyl group and a propionyl group are preferable. By using the substituent B as an acetyl group, a film having an appropriate glass transition point (Tg), elastic modulus and the like can be obtained. By having an aliphatic acyl group having a small number of carbon atoms, such as an acetyl group, an appropriate strength as a film can be obtained without lowering Tg, elastic modulus and the like.
When these aliphatic acyl groups are present, the presence of aromatic acyl groups that are bulky and have higher activity than aliphatic acyl groups are more susceptible to the effects of the present invention. I understood that.
Therefore, in the mixed acid ester of cellulose substituted with both acyl groups of an aromatic acyl group and an aliphatic acyl group having 2 to 4 carbon atoms, the substitution degree of the aromatic acyl group is more effective than the total substitution degree. Therefore, the determination can be made by paying attention to the substitution degree of the aromatic acyl group before the substitution degree of the aliphatic acyl group.

  Although the specific example of the cellulose acylate which can be used for this invention below is shown, it is not limited to the following examples. In addition, the total substitution degree in a table | surface represents the sum total of substitution degree of 2nd-position, 3rd-position, and 6th-position.

The cellulose acylate is a compound having a cellulose skeleton obtained by introducing an acyl group (substituent A) containing at least an aromatic group biologically or chemically using cellulose as a raw material.
The raw material cotton of cellulose acylate has a low polymerization degree obtained by acid hydrolysis of wood pulp such as microcrystalline cellulose as well as natural cellulose such as cotton linter and wood pulp (hardwood pulp, conifer pulp). 300) Cellulose can also be used, and in some cases, it may be mixed and used. Detailed descriptions of these raw material celluloses can be found in, for example, “Plastic Materials Course (17) Fibrous Resin” (Marusawa, Uda, Nikkan Kogyo Shimbun, published in 1970) and Invention Association Publication Technical Report 2001-1745 ( 7 to 8) and “Encyclopedia of Cellulose (page 523)” (edited by Cellulose Society, Asakura Shoten, published in 2000) can be used, and is not particularly limited.

  The cellulose acylate used in the present invention is, for example, cellulose acetate manufactured by Aldrich (acetyl substitution degree 2.45), or cellulose acetate manufactured by Daicel (acetyl substitution degree 2.41 (trade name: L-70), 2.19). (Trade name: FL-70)) 1.76 (trade name: LL-10) as a starting material can be obtained by reaction with the corresponding acid chloride. Usually, when cellulose acetate in which some hydroxyl groups are substituted with acetyl groups is used as a starting material and an acid chloride such as benzoyl chloride is reacted to introduce substituent A, it is preferentially introduced at the 6-position. In order to obtain cellulose acylate in which the substituent A is preferentially substituted at the 2-position and 3-position, the cellulose acetate is once deacetylated under basic conditions, and the 2-position and 3-position acetyl groups are preferentially treated. And then acylated with acid chloride, cellulose acylate having substituent A introduced preferentially at the 2-position and 3-position and acetyl group mainly at the 6-position as substituent B is obtained. . Deacetylation can proceed, for example, in the presence of an amine and water. By adjusting the degree of acetyl substitution of the cellulose acetate as the starting material, the conditions for the deacetylation treatment, and the conditions for introducing the substituent A, a cellulose acylate satisfying the formula (I) can be produced.

  Although there is no restriction | limiting in particular about the viscosity average polymerization degree of the said cellulose acylate, 80-700 are preferable, 90-500 are still more preferable, 100-500 are still more preferable. By setting the average degree of polymerization to 500 or less, the viscosity of the cellulose acylate dope solution does not become too high, and the film production by casting tends to be easy. Moreover, it is preferable for the degree of polymerization to be 140 or more because the strength of the produced film tends to be further improved. The average degree of polymerization can be measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, “Journal of the Textile Society”, Vol. 18, No. 1, pages 105-120, 1962). Specifically, it can be measured according to the method described in JP-A-9-95538.

[Phosphorus compounds]
The cellulose acylate film of the present invention is characterized by containing 10 to 800 ppm of a phosphorus compound. By including a phosphorus compound, internal haze can be reduced and film contrast can be improved.

  The addition amount of a phosphorus compound is 10-800 ppm, 100-700 ppm is preferable and 200-600 ppm is more preferable. When the addition amount is 10 ppm or more, the internal haze can be reduced and the film contrast can be improved, and when the addition amount is 800 ppm or less, the reduction in the expression of Re can be suppressed.

  As a phosphorus compound, it is preferable that they are phosphate ester and its salt. Examples of phosphate esters and salts thereof include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), biphenyl diphenyl phosphate (BDP), tributylmethylammonium dimethyl phosphate (TBMA), sodium methyl (4-nitro). Phenyl) phosphate, trimethyl phosphate (TMP), triethyl phosphate (TEP), triethyl phosphate (TBP), tri (2-ethylhexyl) phosphate (TOP), trixylenyl phosphate (TXP), cresyl diphenyl phosphate (CDP), 2-ethylhexyl diphenyl phosphate, tetra-n-butylammonium phosphate, tris (trimethylsilyl) phosphate, sodium 4-nitrophenyl phosphate And sodium naphthyl phosphate, and salts thereof. Among these, triphenyl phosphate, biphenyl diphenyl phosphate, tributylmethylammonium dimethyl phosphate, and sodium methyl (4-nitrophenyl) phosphate are preferable.

  The phosphorus compound may be added as an additive for the cellulose acylate film, or may be added during the synthesis of the cellulose acylate.

[Cellulose acylate composition]
Next, the cellulose acylate composition that can be used in the present invention will be described.
The cellulose acylate composition used for producing the cellulose acylate film of the present invention contains at least one cellulose acylate and a phosphorus compound.
The cellulose acylate composition preferably contains 70% by mass to 100% by mass of the cellulose acylate, more preferably 80% by mass to 100% by mass, and still more preferably 90% by mass to 100% by mass. % Is included.

The cellulose acylate composition can take various shapes such as particles, powders, fibers, lumps, solutions, and melts.
Since the raw material for film production is preferably in the form of particles or powder, the cellulose acylate composition after drying is pulverized and sieved in order to make the particle size uniform and improve handleability. Also good.

  In the present invention, only one type of cellulose acylate may be used, or two or more types may be mixed and used. In addition, polymer components other than cellulose acylate and various additives can be appropriately mixed. The component to be mixed is preferably one having excellent compatibility with cellulose acylate, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more. It is preferable.

  In the present invention, the cellulose acylate is added with various additives that can generally be added to the cellulose acylate (for example, UV inhibitors, plasticizers, deterioration inhibitors, fine particles, optical property modifiers, etc.) It can be. Moreover, the addition time of the additive to the cellulose acylate may be added in any of the dope preparation steps, and these additives may be added as a preparation step at the end of the dope preparation step.

As an additive, the additive described as general formula (A-1)-(H-1) in the international publication 2011/040468 pamphlet can be used, and especially the following general formula (E-1). It is preferable to add an additive represented by By adding this additive to cellulose acylate, the retardation change depending on the environmental humidity can be reduced, and when it is bonded to the polarizing plate and aged at high temperature and high humidity, the polarizer is deteriorated. A cellulose acylate film that can be suppressed can be provided.

一般式（Ｑ）中、＊側が前記一般式（Ｅ−１）で表される化合物中の複素環に置換しているＮ原子との連結部位である。 In the formula ^(E-1), Y 1 represents a methine group or -N, =. Ra ³¹ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Rb ^31, Rc ^31, Rd ³¹ and Re ³¹ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Q21 represents a single bond, —O—, —S—, or —NRf—, Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and is linked to Ra ³¹ A ring may be formed. X ³¹ , X ³² and X ³³ each independently represent a single bond or a divalent linking group. X ³⁴ represents a linking group selected from the group consisting of divalent linking groups represented by the following general formula (Q).
General formula (Q)

In General Formula (Q), the * side is a linking site with the N atom substituted on the heterocyclic ring in the compound represented by General Formula (E-1).

  As addition amount of these additives, 0.1-20 mass parts is preferable, 0.5-15 mass parts is more preferable, and 1-10 mass parts is especially preferable.

[Method for producing cellulose acylate film]
The present invention relates to a method for producing a cellulose acylate film formed from a composition containing at least one cellulose acylate and a phosphorus compound.
In the cellulose acylate film of the present invention, the cellulose acylate is preferably contained in an amount of 50% by mass or more, more preferably 80% or more, and further preferably 95% or more.

  Although the manufacturing method of the cellulose acylate film of this invention is not specifically limited, For example, it is preferable to manufacture by the solution casting method described below. In the solution casting method, the cellulose acylate film of the present invention can be produced in the same manner as a generally performed method. For example, solution casting can be manufactured with reference to JP-A-2006-241433.

  As described above, it is preferable that the cellulose acylate film of the present invention produced by the melt film forming method or the solution film forming method is further subjected to a stretching treatment. The details of the method for stretching the cellulose acylate film can be referred to the method described in JP2009-235374A.

Re and Rth of the cellulose acylate film of the present invention can be adjusted by the substitution degree distribution and the draw ratio at the 2nd, 3rd and 6th positions of the substituent. Specifically, the cellulose acylate film of the present invention can be a film exhibiting properties of Re (590) of about 220 to 300 nm and Rth of about -30 to 30 nm. Moreover, it can become a film which shows the characteristic of Nz value about 0.5 (specifically 0.25-0.65). However, the optical properties of the cellulose acylate film of the present invention are not limited to this range.
In addition, the cellulose acylate film of the present invention satisfies the above formula (I) and the total of the substitution degrees of the 2nd, 3rd and 6th positions of the substituent A satisfies 0.3 to 2.0. Since acylate is used and a phosphorus compound is contained, the film satisfies the above optical characteristics and has a low humidity dependency of retardation. Specifically, the difference (humidity change value) between Re (590) at 30% humidity and Re (590) at 80% humidity is 10 nm or less, and the humidity dependence of Re is small. Further, the difference (humidity change value) between Rth (590) at 30% humidity and Rth (590) at 80% humidity is 15 nm or less, and the humidity dependence of Re is small.

  Further, the variation in the Re (590) value in the width direction of the film is preferably ± 5 nm, and 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.

  The film thickness of the cellulose acylate film of the present invention is preferably 20 to 80 μm, more preferably 25 to 60 μm, and particularly preferably 30 to 45 μm.

[Phase difference film]
The cellulose acylate film of the present invention can be used as a retardation film.
In addition, the cellulose acylate film of the present invention has a functional layer described in detail on pages 32 to 45 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Are preferably combined. Among these, application of a polarizing film (formation of a polarizing plate), application of an optical compensation layer made of a liquid crystal composition (optical compensation film), and application of an antireflection layer (antireflection film) are preferred.
[Optical compensation film]
The cellulose acylate film of the present invention can be used for optical compensation of a liquid crystal display device. When the cellulose acylate film of the present invention satisfies the optical properties necessary for optical compensation, it can be used as it is as an optical compensation film. Further, in order to satisfy the optical characteristics necessary for optical compensation, one or more other layers, for example, an optically anisotropic layer formed by curing a liquid crystal composition, or a layer made of another birefringent polymer film, After being laminated, it can also be used as an optical compensation film.

[Antireflection film]
The present invention also relates to an antireflection film having the cellulose acylate film of the present invention and an antireflection layer. The antireflection film can be manufactured based on a normal manufacturing method, and can be manufactured by referring to, for example, JP-A-2006-241433.

[Polarizer]
The present invention also relates to 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 a cellulose acylate film of the present invention. Related. The cellulose acylate film may be bonded to a polarizing film as a part of an optical compensation film having an optically anisotropic layer and as a part of an antireflection film having an antireflection layer. Also when it has another layer, it is preferable that the surface of the cellulose acylate film of the present invention is bonded to the surface of the polarizing film. For example, it can manufacture with reference to Unexamined-Japanese-Patent No. 2006-241433.

[Image display device]
The present invention also relates to an image display device including at least one cellulose acylate film of the present invention. The cellulose acylate film of the present invention is used in a display device as a retardation film or an optical compensation film, or as a part of a polarizing plate, an optical compensation film, an antireflection film, or the like.

<Liquid crystal display device>
The cellulose acylate film of the present invention can be incorporated into a liquid crystal display device as a retardation film, or as a polarizing plate, an optical compensation film or an antireflection film using the cellulose acylate film. Examples of the liquid crystal display device include TN type, IPS type, FLC type, AFLC type, OCB type, STN type, ECB type, VA type and HAN type display devices, preferably IPS type and FFS type. In addition, the cellulose acylate film of the present invention can be used for any of transmissive, reflective, and transflective liquid crystal display devices.

  When the cellulose acylate film of the present invention is used in an IPS mode liquid crystal display device, it is preferable to dispose one sheet between the liquid crystal cell and the display surface side polarizing plate or the backlight side polarizing plate. Further, it may function as a protective film for the display surface side polarizing plate or the backlight side polarizing plate, and may be incorporated in a liquid crystal display device as one member of the polarizing plate and disposed between the liquid crystal cell and the polarizing film. By disposing one sheet of the cellulose acylate film of the present invention at the above position, the display characteristics of the IPS mode liquid crystal display device can be improved, and in particular, the color shift can be reduced in the oblique direction during black display. In an embodiment used for optical compensation of an IPS mode liquid crystal display device, Rth of the cellulose acylate film of the present invention is preferably −30 nm to 30 nm, and Re is preferably 220 nm to 300 nm. The Nz value is preferably about 0.5, and specifically, the Nz value is preferably 0.25 to 0.65. In this embodiment, the cellulose acylate film of the present invention is preferably disposed with its in-plane slow axis parallel or perpendicular to the absorption axis of the display surface side polarizing film (or backlight side polarizing film).

  In this aspect, it is preferable that no retardation layer other than the cellulose acylate film exists between the display surface side polarizing film and the backlight side polarizing film and the liquid crystal cell. Therefore, for example, the display surface side polarizing plate or the backlight side polarizing plate has a protective film for a polarizing film other than the cellulose acylate film, and the protective film includes the liquid crystal cell and the display surface side polarizing film or the backlight side. When the protective film is disposed between the polarizing film and the protective film, it is preferable to use an isotropic polymer film in which both Re and Rth are almost zero. A cellulose acylate film described in, for example, 2006-030937 is preferably used.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

<Synthesis of cellulose acylate>
<Synthesis Example 1: Synthesis of A-1>
50 g of cellulose (manufactured by Nippon Paper Industries Co., Ltd .: KC Flock W300) and 1 L of dimethylacetamide were weighed in a 3 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel and stirred at 120 ° C. for 1 hour under a nitrogen stream. Next, 150 g of lithium chloride was added and stirred for 1 hour while allowing to cool. After returning the reaction solution to room temperature, 61 g of pyridine was added, and further a mixture of acetyl chloride 13.9 g and benzoyl chloride 71.7 g was added dropwise at room temperature, and the mixture was further stirred at 100 ° C. for 3 hours. When the reaction solution was added to 10 L of methanol with vigorous stirring, a white solid was precipitated. The white solid was filtered by suction filtration, and dispersed and washed with 2 L of methanol three times. The obtained white solid was vacuum-dried at 100 ° C. for 6 hours to obtain the objective cellulose derivative (A-1) as a white powder (57.8 g).

<Synthesis Example 2: Synthesis of A-2>
50 g of cellulose (manufactured by Nippon Paper Industries Co., Ltd .: KC Flock W300) and 1 L of dimethylacetamide were weighed in a 3 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel and stirred at 120 ° C. for 1 hour under a nitrogen stream. Next, 150 g of lithium chloride was added and stirred for 1 hour while allowing to cool. After returning the reaction solution to room temperature, 123 g of pyridine was added, and a mixture of 2.4 g of acetyl chloride, 47.7 g of propionyl chloride and 121.7 g of benzoyl chloride was added dropwise at room temperature, and the mixture was further stirred at 100 ° C. for 3 hours. . When the reaction solution was added to 10 L of methanol with vigorous stirring, a white solid was precipitated. The white solid was filtered by suction filtration, and dispersed and washed with 2 L of methanol three times. The obtained white solid was vacuum-dried at 100 ° C. for 6 hours to obtain the desired cellulose derivative (A-2) as a white powder (71.6 g).

<Synthesis Example 3: Synthesis of A-3>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.0 g of acetyl chloride and 121.7 g of benzoyl chloride, and the addition amount of pyridine was changed to 95.0 g. (A-3) was obtained as a white powder (61.7 g).

<Synthesis Example 4: Synthesis of A-4>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 12.5 g of acetyl chloride and 125.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 98.5 g. (A-4) was obtained as a white powder (62.2 g).

<Synthesis Example 5: Synthesis of A-5>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.5 g of acetyl chloride and 125.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 97.8 g. (A-5) was obtained as a white powder (62.1 g).

<Synthesis Example 6: Synthesis of A-6>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 12.2 g of acetyl chloride and 130.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 101.9 g. (A-6) was obtained as a white powder (62.6 g).

<Synthesis Example 7: Synthesis of A-7>
In Synthesis Example 1, except that benzoyl chloride was changed to 229.6 g of (4-phenylbenzoyl) chloride, the addition amount of acetyl chloride was changed to 10.1 g, and the addition amount of pyridine was changed to 171.6 g. Of cellulose derivative (A-7) was obtained as a white powder (74.2 g).

<Synthesis Example 8: Synthesis of A-8>
In Synthesis Example 1, the target cellulose derivative (A) was changed in the same manner except that benzoyl chloride was changed to 226.7 g naphthyl chloride, the addition amount of acetyl chloride was changed to 9.1 g, and the addition amount of pyridine was changed to 168.9 g. -8) was obtained as a white powder (73.8 g).

<Synthesis Example 9: Synthesis of A-9>
In Synthesis Example 1, the same except that benzoyl chloride is changed to 136.7 g of chloride (3,4,5-trimethylbenzoyl), the addition amount of acetyl chloride is changed to 13.2 g, and the addition amount of pyridine is changed to 154.5 g. Thus, the objective cellulose derivative (A-9) was obtained as a white powder (68.8 g).

<Synthesis Example 10: Synthesis of A-10>
In Synthesis Example 1, the same procedure was followed except that benzoyl chloride was changed to 264.7 g of (4-pyridylbenzoyl) chloride, the addition amount of acetyl chloride was changed to 7.7 g, and the addition amount of pyridine was changed to 101.9 g. Of cellulose derivative (A-10) was obtained as a white powder (62.6 g).

<Synthesis Example 11: Synthesis of A-11>
In Synthesis Example 1, the same procedure was followed except that benzoyl chloride was changed to 180.9 g of (3-cyanobenzoyl) chloride, the addition amount of acetyl chloride was changed to 8.4 g, and the addition amount of pyridine was changed to 135.6 g. Of cellulose derivative (A-11) was obtained as a white powder (66.5 g).

<Synthesis Example 12: Synthesis of A-12>
In Synthesis Example 2, the addition amount of the acylating agent was changed to 2.4 g of acetyl chloride, 20.0 g of propionyl chloride, and 322.0 g of benzoyl chloride, respectively, and the addition amount of pyridine was changed to 220.7 g. The target cellulose derivative (A-12) was obtained as a white powder (82.0 g).

<Synthesis Example 13: Synthesis of A-13>
Exemplified Compound A-13 was obtained according to the method described in [0151] to [0153] of US 2010/0267942.

<Synthesis Example 14: Synthesis of A-14>
In Synthesis Example 2, the addition amount of the acylating agent was changed to 3.6 g of acetyl chloride, 46.1 g of propionyl chloride and 100.0 g of benzoyl chloride, respectively, and the addition amount of pyridine was changed to 109.3 g. Thus, the objective cellulose derivative (A-14) was obtained as a white powder (74.2 g).

<Synthesis Example 15: Synthesis of A-15>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.5 g of acetyl chloride and 101.7 g of benzoyl chloride, and the addition amount of pyridine was changed to 81.1 g. (A-15) was obtained as a white powder (60.1 g).

<Synthesis Example 16: Synthesis of A-16>
In Synthesis Example 2, the addition amount of the acylating agent was changed to 2.9 g of acetyl chloride, 45.5 g of propionyl chloride, and 106.7 g of benzoyl chloride, respectively, and the addition amount of pyridine was changed to 112.1 g. The target cellulose derivative (A-16) was obtained as a white powder (72.2 g).

<Synthesis Example 17: Synthesis of A-17>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 9.1 g of acetyl chloride and 105.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 81.7 g. (A-17) was obtained as a white powder (60.1 g).

<Synthesis Example 18: Synthesis of A-18>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.8 g of acetyl chloride and 105.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 83.6 g. (A-18) was obtained as a white powder (60.4 g).

<Synthesis Example 19: Synthesis of A-19>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 12.0 g of acetyl chloride and 108.4 g of benzoyl chloride and the addition amount of pyridine was changed to 86.2 g, respectively. (A-19) was obtained as a white powder (60.7 g).

<Synthesis Example 20: Synthesis of A-20>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 10.6 g of acetyl chloride and 103.4 g of benzoyl chloride and the addition amount of pyridine was changed to 81.6 g, respectively. (A-20) was obtained as a white powder (60.1 g).

<Synthesis Example 21: Synthesis of A-21>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 12.5 g of acetyl chloride and 101.7 g of benzoyl chloride and the addition amount of pyridine was changed to 81.7 g, respectively. (A-21) was obtained as a white powder (60.2 g).

<Synthesis Example 22: Synthesis of A-22>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 9.8 g of acetyl chloride and 103.4 g of benzoyl chloride, and the addition amount of pyridine was changed to 81.1 g. (A-22) was obtained as a white powder (60.0 g).

<Synthesis Example 23: Synthesis of A-23>
In Synthesis Example 2, the addition amount of the acylating agent was changed to 2.7 g of acetyl chloride, 52.2 g of propionyl chloride, and 103.4 g of benzoyl chloride, respectively, and the addition amount of pyridine was changed to 116.0 g. Thus, the objective cellulose derivative (A-23) was obtained as a white powder (72.5 g).

<Synthesis Example 24: Synthesis of A-24>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.5 g of acetyl chloride and 86.7 g of benzoyl chloride and the addition amount of pyridine was changed to 70.3 g, respectively. (A-24) was obtained as a white powder (58.8 g).

<Synthesis Example 25: Synthesis of A-25>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 9.1 g of acetyl chloride and 141.7 g of benzoyl chloride, and the addition amount of pyridine was changed to 108.0 g. (A-25) was obtained as a white powder (63.2 g).

<Synthesis Example 26: Synthesis of B-1>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 15.2 g of acetyl chloride and 31.7 g of benzoyl chloride, and the addition amount of pyridine was changed to 33.5 g. (B-1) was obtained as a white powder (54.5 g).

<Synthesis Example 27: Synthesis of B-2>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 7.7 g of acetyl chloride and 370.1 g of benzoyl chloride and the addition amount of pyridine was changed to 270.5 g, respectively. (B-2) was obtained as a white powder (82.7 g).

<Synthesis Example 28: Synthesis of B-3>
In Synthesis Example 1, the target cellulose derivative was similarly obtained except that the addition amount of the acylating agent was changed to 7.4 g of acetyl chloride and 365.1 g of benzoyl chloride, respectively, and the addition amount of pyridine was changed to 266.7 g. (B-3) was obtained as a white powder (82.2 g).

<Synthesis Example 29: Synthesis of B-4>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 11.3 g of acetyl chloride and 105.0 g of benzoyl chloride, and the addition amount of pyridine was changed to 83.3 g. (B-4) was obtained as a white powder (60.3 g).

<Synthesis Example 30: Synthesis of B-5>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 10.8 g of acetyl chloride and 103.4 g of benzoyl chloride and the addition amount of pyridine was changed to 81.7 g, respectively. (B-5) was obtained as a white powder (60.1 g).

<Synthesis Example 31: Synthesis of B-6>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 9.1 g of acetyl chloride and 103.4 g of benzoyl chloride, and the addition amount of pyridine was changed to 80.5 g. (B-6) was obtained as a white powder (59.9 g).

<Synthesis Example 32: Synthesis of B-7>
The same cellulose derivative as in Synthesis Example 1 except that the addition amount of the acylating agent was changed to 2.4 g of acetyl chloride and 475.1 g of benzoyl chloride, and the addition amount of pyridine was changed to 341.9 g. (B-7) was obtained as a white powder (91.1 g).

[Production Example 1: Production of cellulose acylate film]
Using each of the produced cellulose acylates, cellulose acylate films shown in the following table were produced by the following methods.

<Preparation of cellulose acylate solution>
The following raw materials were put into a mixing tank, stirred while heating, dissolved, and a solution having a cellulose acylate solution was prepared. In addition, A-13 did not add a phosphorus compound at the time of solution preparation.

Cellulose acylate shown in the following table 100 parts by mass Methylene chloride (first solvent) 402 parts by mass Methanol (second solvent) 60 parts by mass Phosphorus compound As described in the table Additive A shown below As described in the table

<Preparation of cellulose acylate film sample>
562 parts by mass of a cellulose acylate solution composition was cast using a band casting machine. Each of the cellulose acylate films shown in the following table is obtained by subjecting a film having a residual solvent amount of 15% by mass to a glass transition temperature + 25 ° C. at a stretching ratio shown in the following table and a fixed end uniaxial stretching or a free end uniaxial stretching. Was made.

<Evaluation of cellulose acylate film sample>
For the evaluation of the film sample, a part (120 mm × 120 mm) of each film sample obtained above was prepared, and the retardation value was set to “KOBRA 21ADH” (manufactured by Oji Scientific Instruments) with a wavelength of 590 nm. Re and Rth with respect to light were measured. The results are shown in the table below.

<Evaluation>
The internal haze, film contrast, and humidity change value of each film were measured and evaluated as follows. The results are shown in the table below.

1. Measurement of internal haze Add a few drops of silicone oil to the front and back of the film, and use two 1 mm thick glass plates (micro slide glass product number S9111, made by MATSUNAMI) from the front and back to completely In a state where the glass plate and the obtained film were optically adhered and the surface haze was removed, the haze was measured according to JIS K-7136 using a haze meter NDH2000 (Nippon Denshoku Industries Co., Ltd.) and separately measured. A value obtained by subtracting haze measured by sandwiching only silicone oil between two glass plates was calculated as the internal haze of the film.

2. Measurement of Film Contrast A polarizing plate having a polarization performance of 99.995% or more represented by the following formula is placed in a crossed Nicol state, a film is inserted between them, and the film is rotated so that the minimum transmittance (Imin) Asked. Thereafter, one side of the polarizing plate was rotated by 90 ° in a state where the minimum transmittance was reached, to obtain a paranicol state, and the transmittance (Imax) at that time was determined. (Imin) / (Imax) was measured as film contrast. It shows that there are few light leaks, so that the numerical value of film contrast is large.

P (%) = ((Tp−Tc) / (Tp + Tc)) ^1/2 × 100
(Tp represents the transmittance in the para-Nicol state, and Tc represents the transmittance in the crossed Nicol state.

3. Humidity change value Difference between in-plane retardation (Re) value and thickness direction retardation (Rth) value measured at 25 ° C. and 30% RH environment, and Re value and Rth value measured at 25 ° C. and 80% RH environment Was the humidity change value.

表中、ＴＰＰは、トリフェニルフォスフェート、ＢＤＰは、ビフェニルジフェニルフォスフェート、ＴＢＭＡは、トリブチルメチルアンモニウムジメチルフォスフェート、化合物Ａは、ソディウムメチル（４−ニトロフェニル）フォスフェート、及び化合物Ｂは、テトラ（ｎ−ブチル）アンモニウムフォスフェートを表す。
表中の全置換度とは、２位、３位、６位の置換度の合計を表す。置換基Bにおいて、Ａはアセチル基、Ｐはプロピオニル基を表す。

In the table, TPP is triphenyl phosphate, BDP is biphenyl diphenyl phosphate, TBMA is tributylmethylammonium dimethyl phosphate, compound A is sodium methyl (4-nitrophenyl) phosphate, and compound B is tetra Represents (n-butyl) ammonium phosphate.
The total substitution degree in the table represents the total of the substitution degree at the 2nd, 3rd and 6th positions. In the substituent B, A represents an acetyl group, and P represents a propionyl group.

  From the table, the cellulose acylate containing the cellulose acylate satisfying the formula (I), in which the total substitution degree at the 2-position, 3-position and 6-position of the substituent A is 0.3 to 2.0 and the phosphorus compound It can be seen that the film has a low internal haze, a high film contrast, and a low humidity change value as compared with the comparative example.

[Production Example 2: Production of IPS mode liquid crystal display device]
(Preparation of polarizing plate)
1) Saponification of Film Each film produced in Examples and Comparative Examples, and Fujitac TF80UL (manufactured by FUJIFILM Corporation) was adjusted to a 1.5 mol / L potassium hydroxide aqueous solution (saponification solution) adjusted to 55 ° C. After dipping for 3 minutes, the film was washed with water, then dipped in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, and then passed through a washing bath. Then, draining with an air knife was repeated three times, and after dropping the water, the film was retained in a drying zone at 70 ° C. for 15 seconds and dried to produce a saponified film.

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

3) Bonding One surface of the polarizing film thus obtained was prepared in the saponified examples and comparative examples using PVA (manufactured by Kuraray Co., Ltd., PVA-117H) 3% aqueous solution as an adhesive. The saponified surface of each film was bonded together, and the saponified surface of TF80UL was bonded to the other surface. The polarizing film was bonded so that the absorption axis direction of the polarizing film and the slow axis direction of the film were orthogonal to each other.

<Evaluation of mounting on IPS mode liquid crystal display>
Each produced polarizing plate was produced by the Example and the comparative example instead of the visual recognition side polarizing plate incorporated in the IPS type | mold liquid crystal display device (37 type high-vision liquid crystal television monitor (37Z2000), Toshiba Corporation make). When each film was incorporated so as to be on the liquid crystal cell side and the visibility was confirmed, sufficient viewing angle compensation was achieved, and it was confirmed that good visibility could be secured. Also, good visibility was ensured even under high temperature and high humidity, and no light leakage was observed. On the other hand, when the polarizing plate produced with the film of the comparative example was incorporated, viewing angle compensation was insufficient, and light leakage particularly when viewed from an oblique direction was strongly observed.

Claims (15)

At least cellulose acylate satisfying the following formula (I), in which the total substitution degree of the 2-position, 3-position, and 6-position of the acyl group (substituent A) containing an aromatic group is 0.3 to 2.0. A cellulose acylate film comprising one type and a phosphorus compound of 10 to 800 ppm and having an internal haze value converted to a film thickness of 60 μm of 0.005 to 0.10.
Formula (I) 1 ≦ (DS2 + DS3) / DS6 ≦ 5
(In the formula, DS2, DS3, and DS6 represent the degrees of substitution of the substituent A at the 2-position, 3-position, and 6-position of cellulose acylate, respectively.) The cellulose acylate film according to claim 1, wherein the phosphorus compound is selected from a phosphate ester and a salt thereof. The cellulose acylate according to claim 1 or 2, wherein the in-plane retardation Re (590) at a wavelength of 590 nm is 220 to 300 nm, and the retardation Rth (590) in the thickness direction at a wavelength of 590 nm is -30 to 30 nm. the film. The cellulose acylate film according to claim 1, wherein the substituent A is a substituent represented by the following general formula (I).

Formula (I)
(In the formula, X represents a hydrogen atom or a substituent. N represents 0 or an integer of 1 to 5. When n is 2 or more, a plurality of Xs are connected to each other to form a condensed polycycle. May be good.) The cellulose acylate film according to claim 1, wherein the substituent A is a benzoyl group. The cellulose acylate film according to any one of claims 1 to 5, wherein the cellulose acylate further has an aliphatic acyl group (substituent B) having 2 to 20 carbon atoms. The cellulose acylate film according to claim 6, wherein the substituent B is selected from an acetyl group, a propionyl group, a butanoyl group, and a hexanoyl group. Furthermore, the cellulose acylate film of any one of Claims 1-7 which contains 0.1-20 mass parts of additives represented by the following general formula (E-1).

(In General Formula (E-1), Y ¹ represents a methine group or —N═. Ra ³¹ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Rb ³¹ , Rc ³¹ , Rd ³¹ and Re ³¹ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and Q ²¹ represents a single bond, —O—, —S—, or —NRf—. , Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and may be linked to Ra ³¹ to form a ring, and X ³¹ , X ^32, and X ³³ each represent Independently represents a single bond or a divalent linking group, and X ³⁴ represents a linking group selected from the group consisting of a divalent linking group represented by the following general formula (Q).
General formula (Q)

(In General Formula (Q), the * side is a linking site with the N atom substituted on the heterocyclic ring in the compound represented by General Formula (E-1).) The difference between the in-plane retardation Re (590) at a wavelength of 590 nm at 30% humidity and the in-plane retardation Re (590) at a wavelength of 590 nm at 80% humidity is 10 nm or less, and the surface at a wavelength of 590 nm at 30% humidity The cellulose acylate film according to any one of claims 1 to 8, wherein a difference between the inner retardation Rth (590) and the in-plane retardation Rth (590) at a wavelength of 590 nm at a humidity of 80% is 15 nm or less. . The cellulose acylate film according to claim 1, wherein the film thickness is 20 to 80 μm. The retardation film which consists of a cellulose acylate film of any one of Claims 1-10. The optical compensation film which consists of or contains the cellulose acylate film of any one of Claims 1-10. The antireflection film which has a cellulose acylate film of any one of Claims 1-10, and an antireflection layer. The polarizing plate which has a polarizing film and the cellulose acylate film of any one of Claims 1-10. A liquid crystal display device comprising the polarizing plate according to claim 14.