JP2017129792A - Cellulose acylate film, polarizing plate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose acylate film that can provide a polarizing plate excellent in durability in a high temperature and high humidity environment and that has little dimensional change by changes in ambient humidity and has excellent optical characteristics, and a polarizing plate and a liquid crystal display device including the cellulose acylate film.SOLUTION: The cellulose acylate film comprises a cellulose acylate having an average acyl group substitution degree of 2.00 or more and less than 2.65, a compound A satisfying requirements a1 and a2 described in the specification, a compound B represented by general formula (I) described in the specification, and a compound C satisfying requirements c1 and c2 described in the specification; and the film shows a Rth/d of 1.0 or more and less than 5.5. The ratio Rth/d is obtained by dividing Rth by d, where Rth is a retardation value [unit: nm] in a film thickness direction of the cellulose acylate film at a wavelength of 590 nm, and d is a film thickness [unit: μm] of the cellulose acylate film.SELECTED DRAWING: None

Description

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

Cellulose acylate films are used in various applications such as polarizing plate protective films.
The polarizing plate usually comprises a polarizer and a polarizing plate protective film, and the polarizer is generally produced by stretching a polyvinyl alcohol (PVA) film dyed with iodine. The polarizing plate is used for a liquid crystal display device or the like.

Patent Document 1 describes a cellulose acylate film containing a barbituric acid derivative. By using this cellulose acylate film as a polarizing plate protective film, the durability of the polarizing plate in a high-temperature and high-humidity environment is described. It is described to improve. Here, the durability of the polarizing plate (polarizing plate durability) means that the absorption axes of the two polarizing plates are orthogonal to each other before and after being left for a certain period of time in a high temperature and high humidity environment. It represents that there is little change amount of the light transmittance (orthogonal transmittance) measured by the apparatus using the arrangement state or the principle based on it.
Patent Document 2 describes that the surface hardness is improved by adding a compound having a urethane bond to a cellulose acylate film.

International Publication No. 2014/148559 International Publication No. 2015/151683

In recent years, in addition to thinning of the liquid crystal display device, the opportunity for the liquid crystal display device to be used outdoors has increased, and further improvement of the durability of the polarizing plate in a high temperature and high humidity environment has been demanded.
In addition, the polarizing plate protective film has little dimensional change (humidity dimensional change) due to changes in environmental humidity, and has excellent optical characteristics (particularly optical characteristics suitable for a liquid crystal cell in a VA (Vertically Aligned) mode. ) Is required.
Patent Document 1 describes that the durability of a polarizing plate in a high-temperature and high-humidity environment is improved by using a barbituric acid derivative, but there is room for further improvement in durability. In addition, there is no description about suppression of dimensional changes due to changes in environmental humidity and optical characteristics.
Patent Document 2 describes the use of a compound having a urethane bond, but mentions improvement of durability of a polarizing plate in a high temperature and high humidity environment, suppression of dimensional change due to humidity change, and optical characteristics. It has not been.

  An object of the present invention is to provide a polarizing plate excellent in durability under a high-temperature and high-humidity environment, a dimensional change due to a change in environmental humidity, and a cellulose acylate film excellent in optical characteristics, and the cellulose acylate. It is providing the polarizing plate containing a film and a liquid crystal display device.

  The inventor has intensively studied and found that the above-described problems can be solved by the following means.

<1>
Cellulose acylate having an average acyl group substitution degree of 2.00 or more and less than 2.65;
Compound A satisfying the following requirements a1 and a2,
Compound B represented by the following general formula (I):
Compound C satisfying the following requirements c1 and c2,
Containing
A cellulose acylate film having an Rth / d of 2.2 or more and less than 5.5.
Rth / d indicates a value obtained by dividing Rth by d, Rth is a retardation [unit: nm] in the film thickness direction of the cellulose acylate film at a wavelength of 590 nm, and d is a film thickness [unit: μm] of the cellulose acylate film. ].
a1: At least one structure represented by —C (═O) —NH—Ar is present in the molecule. Ar represents an unsubstituted aromatic ring.
a2: The value obtained by dividing the molecular weight of Compound A by the number of aromatic rings contained in the molecule of Compound A is 220 or less.
Formula (I)

In general formula (I), R ²⁶ represents an alkyl group, an alkynyl group or an aromatic hydrocarbon group, and R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aromatic hydrocarbon group or an aromatic group. Represents a heterocyclic group, and R ²⁹ represents a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may each independently have a substituent.
c1: The absolute value ΔSP (1) of the difference between the SP value of Compound B and the SP value of Compound C is 1.0 MPa ^1/2 or more.
c2: The absolute value ΔSP (2) of the difference between the SP value of cellulose acylate and the SP value of compound C is 1.5 MPa ^1/2 or less.
However, SP value represents the value of the solubility parameter measured by the Hoy method.
<2>
The cellulose acylate film according to <1>, wherein the content of the compound A is 15% by mass or more and 30% by mass or less with respect to the total mass of the cellulose acylate.
<3>
The cellulose acylate film according to <1> or <2>, wherein the compound A is a compound represented by the following general formula (J).
Formula ^{(J): Z- (L 12} -L 11 -O-C (= O) -NH-Ar) n1
In general formula (J), Ar represents an unsubstituted aromatic ring. L ¹¹ represents a single bond or an alkylene group, and the alkylene group may have a substituent. L ¹² represents a single bond or a linking group selected from linking groups consisting of —O—, —NR ¹ —, —S—, —C (═O) —, and combinations thereof. R ¹ represents a hydrogen atom or a substituent. Z represents an n1-valent group. n1 represents an integer of 1 to ^6, if L ^{11, L 12} and Ar there are a plurality, a plurality of ^{L 11, L 12} and Ar may be the same or different from each other.
<4>
The cellulose acylate film according to <3>, wherein the sum of the molecular weights of L ¹¹ , L ¹² , and Z is 40 or more and 100 or less.
<5>
The cellulose acylate film according to any one of <1> to <4>, wherein the compound C is a polyester having a weight average molecular weight of 800 or more.
<6>
The cellulose acylate film according to any one of <1> to <5>, wherein the content of the compound C is 0.1% by mass or more and 10% by mass or less with respect to the total mass of the cellulose acylate.
<7>
A polarizing plate having the cellulose acylate film according to any one of <1> to <6>.
<8>
A liquid crystal display device comprising the polarizing plate according to <7>.

  According to the present invention, a cellulose acylate film which can provide a polarizing plate excellent in durability under a high-temperature and high-humidity environment, has a small dimensional change due to a change in environmental humidity, and has excellent optical characteristics, and the cellulose acylate. A polarizing plate including a film and a liquid crystal display device can be provided.

Hereinafter, the present invention will be described in detail.
The following description may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, Rth represents retardation [unit: nm] in the film thickness direction of the cellulose acylate film at a wavelength of 590 nm. Rth can be measured by making light having a wavelength of 590 nm incident in the normal direction of the film in an Axo Scan (manufactured by Axometrics).

  In this specification, a weight average molecular weight (Mw) and a number average molecular weight (Mn) are defined as a polystyrene conversion value by gel permeation chromatography (GPC) measurement. In this specification, the weight average molecular weight and the number average molecular weight are HLC-8220 (manufactured by Tosoh Corporation) and TSKgel (registered trademark) Super AWM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15) is used as a column. Unless otherwise stated, the eluent was measured using an N-methylpyrrolidinone (NMP) solution of 10 mmol / L lithium bromide unless otherwise specified.

[Cellulose acylate film]
The cellulose acylate film of the present invention is
Cellulose acylate having an average acyl group substitution degree of 2.00 or more and less than 2.65;
Compound A satisfying the following requirements a1 and a2,
Compound B represented by the following general formula (I):
Compound C satisfying the following requirements c1 and c2,
Containing
A cellulose acylate film having an Rth / d of 2.2 [nm / μm] or more and less than 5.5 [nm / μm].
Rth / d indicates a value obtained by dividing Rth by d, Rth is a retardation [unit: nm] in the film thickness direction of the cellulose acylate film at a wavelength of 590 nm, and d is a film thickness [unit: μm] of the cellulose acylate film. ].
a1: At least one structure represented by —C (═O) —NH—Ar is present in the molecule. Ar represents an unsubstituted aromatic ring.
a2: The value obtained by dividing the molecular weight of Compound A by the number of aromatic rings contained in the molecule of Compound A is 220 or less.
Formula (I)

In general formula (I), R ²⁶ represents an alkyl group, an alkynyl group or an aromatic hydrocarbon group, and R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aromatic hydrocarbon group or an aromatic group. Represents a heterocyclic group, and R ²⁹ represents a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may each independently have a substituent.
c1: The absolute value ΔSP (1) of the difference between the SP value of Compound B and the SP value of Compound C is 1.0 MPa ^1/2 or more.
c2: The absolute value ΔSP (2) of the difference between the SP value of cellulose acylate and the SP value of compound C is 1.5 MPa ^1/2 or less.
However, SP value represents the value of the solubility parameter measured by the Hoy method.

[Compound A]
The compound A contained in the cellulose acylate film of the present invention will be described below.
Compound A satisfies the following requirements a1 and a2.
a1: At least one structure represented by —C (═O) —NH—Ar is present in the molecule. Ar represents an unsubstituted aromatic ring.
a2: The value obtained by dividing the molecular weight of Compound A by the number of aromatic rings contained in the molecule of Compound A is 220 or less.
Polarizing plates are known to have a decreased degree of polarization (durability decreases) due to color loss in a high-temperature and high-humidity environment. The cause is the cellulose acylate film in which iodine in the polarizer is a polarizing plate protective film. It is possible to diffuse inside. Therefore, it is considered that the durability of the polarizing plate can be improved by using a cellulose acylate film in which iodine is difficult to diffuse.
When the compound A satisfies the requirement a1, the hydrogen bond interaction between the NH group in the structure represented by —C (═O) —NH—Ar and the carbonyl group of the cellulose acylate results in the cellulose acylate film. It is thought that iodine is less likely to diffuse from the polarizer into the cellulose acylate film, and the distance between the polymer chains of the cellulose acylate hardly changes even when the environmental humidity changes, and the dimensions are stable. It is thought to do.
The aromatic ring (Ar) directly connected to the —C (═O) —NH group has a rigid structure and is considered to have a function of making iodine difficult to diffuse by suppressing the movement of the cellulose acylate in the cellulose acylate film. . Further, it is considered that the distance from the molecular chain of cellulose acylate is sufficiently close by having no substituent (unsubstituted) on the aromatic ring. Further, by satisfying the requirement a2, the presence of a certain percentage of the number of aromatic rings increases the refractive index anisotropy in the stretched and oriented cellulose acylate film, resulting in appropriate optical expression (excellent optical properties). It is considered that
Ar is preferably a benzene ring.

The compound A is preferably a compound represented by the following general formula (J).
Formula ^{(J): Z- (L 12} -L 11 -O-C (= O) -NH-Ar) n1

In general formula (J), Ar represents an unsubstituted aromatic ring. L ¹¹ represents a single bond or an alkylene group, and the alkylene group may have a substituent. L ¹² represents a single bond or a linking group selected from linking groups consisting of —O—, —NR ¹ —, —S—, —C (═O) —, and combinations thereof. R ¹ represents a hydrogen atom or a substituent. Z represents an n1-valent group. n1 represents an integer of 1 to ^6, if L ^{11, L 12} and Ar there are a plurality, a plurality of ^{L 11, L 12} and Ar may be the same or different from each other.

When L ¹¹ represents an alkylene group, the alkylene group may be linear, branched, or cyclic, and one or more cyclic alkylene groups (cycloalkylene groups) and one or more linear groups Alternatively, an alkylene group linked to a branched alkylene group may be used. Specific examples of the linear or branched alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. The linear or branched alkylene group includes 1 to 1 carbon atoms. 20 alkylene groups are preferred, C1-C12 alkylene groups are more preferred, C1-C8 alkylene groups are more preferred, C1-C3 alkylene groups are particularly preferred, methylene groups, ethylene groups, or A propylene group is most preferred. The cyclic alkylene group is preferably a cyclohexylene group which may have a substituent. The alkylene group may have a substituent. Examples of the substituent that the alkylene group may have include a substituent selected from the following substituent group T. Among these, as a substituent which an alkylene group has, an alkyl group, an acyl group, an aryl group, an alkoxy group, and a carbonyl group are preferable.
It is preferable that the linear or branched alkylene group does not have a substituent. The cyclic alkylene group preferably has a substituent.

L ¹² represents a single bond or ^{-O -, - NR 1 -,} - S -, - C (= O) - represents any or a group comprising a combination of these, among others a single bond, an oxygen atom, -NR ¹ - Or -C (= O)-. R ¹ represents a hydrogen atom or a substituent, and examples of the substituent include an alkyl group, an alkenyl group, an aryl group, and an acyl group. A hydrogen atom or an alkyl group having 1 to 8 carbon atoms and 2 to 8 carbon atoms can be used. Are preferably an alkenyl group, an alkynyl group having 2 to 8 carbon atoms, and an aryl group having 6 to 18 carbon atoms (for example, a phenyl group and a naphthyl group), more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. .

L ¹² is preferably a single bond, —O— *, —OC (═O) — *, —C (═O) O— *, —NR ¹ — *, —R ¹ N— *. More preferably, it is a bond. Here, * represents a bonding position to Z or a position to bond to an adjacent group on the Z side.

Substituent group T:
An alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms such as methyl group, ethyl group, isopropyl group, tert-butyl group, n-octyl group, n -Decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms). A vinyl group, an allyl group, a 2-butenyl group, a 3-pentenyl group, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms). , For example, propargyl group, 3-pentynyl group, etc.), aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, Is preferably 6 to 12, and examples thereof include a phenyl group, a biphenyl group, and a naphthyl group.), An amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and particularly preferably 0 to 6 carbon atoms). For example, an amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dibenzylamino group, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1). -8, for example, methoxy group, ethoxy group, butoxy group, etc.), aryloxy group (preferably having 6-20 carbon atoms, more preferably 6-16, particularly preferably 6-12, Phenyloxy group, 2-naphthyloxy group, etc.), acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms). Especially preferably, it is 1-12, for example, an acetyl group, a benzoyl group, a formyl group, a pivaloyl group etc. are mentioned, An alkoxycarbonyl group (preferably C2-C20, More preferably, it is 2-16, Most preferably, 2-12, for example, a methoxycarbonyl group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having a carbon number of 7-20, more preferably 7-16, particularly preferably 7-10, For example, a phenyloxycarbonyl group etc. are mentioned), an acyloxy group (preferably 2-20 carbon atoms, More preferably, it is 2-16, Most preferably, it is 2-10, for example, an acetoxy group, a benzoyloxy group, etc. are mentioned. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, Especially preferably, it is 2-10, for example, an acetylamino group, a benzoylamino group, etc. are mentioned. ), An alkoxycarbonylamino group (preferably having a carbon number of 2 to 20, more preferably 2 to 16, particularly preferably 2 to 12, such as a methoxycarbonylamino group), an aryloxycarbonylamino group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group, and a sulfonylamino group (preferably 1 to 20 carbon atoms, more preferably Is 1 to 16, particularly preferably 1 to 12, and examples thereof include a methanesulfonylamino group and a benzenesulfonylamino group.), A sulfamoyl group (preferably having a carbon number of 0 to 20, more preferably 0 to 16, particularly Preferably it is 0-12, for example, sulfamoyl group, methylsulfamoyl group A dimethylsulfamoyl group, a phenylsulfamoyl group, etc.), a carbamoyl group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as a carbamoyl group, methyl A carbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, etc.), an alkylthio group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as a methylthio group, an ethylthio group, etc. ), An arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms such as a phenylthio group), a sulfonyl group (preferably carbon atoms). Number 1-20, more preferably 1-16, particularly preferably 1-12, examples Mesyl group, tosyl group, etc.), sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as methanesulfinyl group and benzenesulfinyl group). ), A urethane group, a ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 and particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group. ), Phosphoric acid amide groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as diethyl phosphoric acid amide and phenylphosphoric acid amide), hydroxyl Group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfur atom Pho group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms. Atoms, oxygen atoms, sulfur atoms, specifically, for example, imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group and the like can be mentioned. ) And a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms such as a trimethylsilyl group and a triphenylsilyl group).
These substituents may be further substituted. Moreover, when there are two or more substituents, the two or more substituents may be the same or different. If possible, they may be linked together to form a ring.

Z represents an n1-valent (1-6 valent) linking group, preferably a 2-6 valent linking group, more preferably a 2-4 valent linking group, and a divalent or trivalent linking group. More preferably, it is a group. That is, n1 represents an integer of 1 to 6, preferably represents an integer of 2 to 6, more preferably represents an integer of 2 to 4, and further preferably represents 2 or 3.
Z may consist of at least one of a linear, branched or cyclic aliphatic group and an aromatic group, or a combination of these groups with an oxygen atom, a linear or branched alkylene group. It is also preferable. The aliphatic group contained as Z is preferably a saturated aliphatic group.
By using a group containing at least one of a branched or cyclic aliphatic group and aromatic group, a rigid structure is obtained, and the inclusion of this compound tends to further improve the surface hardness of the film. 1-20 are preferable, as for carbon number contained in Z, 1-15 are more preferable, and 1-12 are still more preferable.
Z may have a substituent, and specific examples of the substituent include a substituent selected from the substituent group T described above, but it is preferable that Z does not have a substituent.

The compound represented by the general formula ^{(J), L 11, L} 12, and the molecular weight of the sum of the partial structure is Z (i.e., the molecular weight of the sum + n1 pieces of ^{L 12} of molecular weight + n1 pieces of ^{L 11} of Z Is preferably 40 or more and 100 or less, more preferably 50 or more and 95 or less, and still more preferably 60 or more and 90 or less.

Specifically, the linking groups exemplified below are preferable. Note that * represents a position bonding with ^{L 12.}

  Compound A has at least one structure represented by -C (= O) -NH-Ar, but the number of structures represented by -C (= O) -NH-Ar is 2-6. It is preferably 2-4, more preferably 2 or 3, even more preferably.

  Regarding compound A, matters described in International Publication Nos. 2014/133041 and 2015/151683 can also be referred to in the present invention.

  Compound A desirably contains a certain amount of aromatic rings in the molecule in order to obtain optical expression. The value obtained by dividing the molecular weight of Compound A by the number of aromatic rings contained in the molecule of Compound A is preferably from 143 to 220, more preferably from 150 to 200, and particularly preferably from 155 to 180. .

Hereinafter, although compound A preferably used by this invention is illustrated, this invention is not limited to these.
Here, “k” in (1-1-k) is an integer of 1 to 10. For example, when k = 2, the compound number is (1-1-2), and — ( It means that _{k of} CH ₂ ) _k- is 2.

It is preferable that the content rate of the said compound A contained in a cellulose acylate film is 15 mass% or more with respect to the total mass of a cellulose acylate. Since the diffusion of iodine into the cellulose acylate film can be suppressed by setting the content of Compound A to 15% by mass or more, the durability of the polarizing plate can be improved, and the dimensions accompanying changes in humidity Change can be suppressed.
The content of Compound A is more preferably 16% by mass or more, and further preferably 20% by mass or more, based on the total mass of the cellulose acylate. Further, the content of Compound A is preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 24% by mass or less, based on the total mass of the cellulose acylate.

[Compound B]
The compound B contained in the cellulose acylate film of the present invention will be described below.
Compound B is a compound represented by general formula (I).

Formula (I)

In general formula (I), R ²⁶ represents an alkyl group, an alkynyl group or an aromatic hydrocarbon group, and R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aromatic hydrocarbon group or an aromatic group. Represents a heterocyclic group, and R ²⁹ represents a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may each independently have a substituent.

The alkyl group, alkynyl group, aromatic hydrocarbon group, alkenyl group, and aromatic heterocyclic group represented by R ²⁶ , R ²⁷ , R ²⁸ or R ^{29 in} general formula (I) will be described below.
The alkyl group may be linear, branched or cyclic. 1-20 are preferable, as for carbon number of a linear alkyl group, 1-10 are more preferable, 1-5 are more preferable, and 1-3 are especially preferable. As the linear alkyl group, a methyl group or an ethyl group is preferable. 3-20 are preferable, as for carbon number of a branched alkyl group, 3-10 are more preferable, and 3-5 are more preferable. 3-20 are preferable, as for carbon number of a cyclic | annular alkyl group, 3-10 are more preferable, 4-8 are more preferable, and 5 or 6 is especially preferable. Examples of the cyclic alkyl group include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, and a cyclohexyl group is particularly preferable.
2-20 are preferable, as for carbon number of an alkynyl group, 2-10 are more preferable, and 2-5 are more preferable.
6-20 are preferable, as for carbon number of an aromatic hydrocarbon group, 6-16 are more preferable, and 6-12 are more preferable. The aromatic hydrocarbon group may be monocyclic or polycyclic. For example, a phenyl group, a naphthyl group, etc. are mentioned, A phenyl group is preferable.
2-20 are preferable, as for carbon number of an alkenyl group, 2-10 are more preferable, and 2-5 are more preferable. For example, a vinyl group and an allyl group are mentioned.
6-20 are preferable, as for carbon number of an aromatic heterocyclic group, 6-16 are more preferable, and 6-12 are more preferable. The aromatic heterocyclic group may be monocyclic or polycyclic.

R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may each independently have a substituent. There is no restriction | limiting in particular as a substituent, A linear, branched or cyclic alkyl group (preferably C1-C10), an alkenyl group (preferably C2-C20), an alkynyl group (preferably carbon number). 2 to 20), an aryl group (preferably 6 to 26 carbon atoms), a heterocyclic group, an alkoxy group (preferably 1 to 20 carbon atoms), an aryloxy group (preferably 6 to 26 carbon atoms), an alkylthio group (preferably Is an arylthio group (preferably 6 to 26 carbon atoms), a sulfonyl group (preferably 1 to 20 carbon atoms), an acyl group (preferably 20 or less carbon atoms), an alkoxycarbonyl group (preferably Has 2 to 20 carbon atoms, an aryloxycarbonyl group (preferably 7 to 20 carbon atoms), an amino group (preferably 0 to 20 carbon atoms), a sulfonamide group (preferably C0-20), sulfamoyl group (preferably C0-20), acyloxy group (preferably C1-20), carbamoyl group (preferably C1-20), acylamino group (preferably Are carbon number 1-20), cyano group, hydroxy group, mercapto group, carboxyl group, halogen atom and the like. The above substituent may be further substituted with the above substituent.

The compound represented by the general formula (I) is preferably an alkyl group in which at least one of R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ is substituted with a group having a ring structure. Among these, R ²⁶ or R ²⁹ is preferably an alkyl group substituted with a group having a ring structure. Here, the ring of the group having a ring structure is a benzene ring, naphthalene ring, cyclopentane ring, cyclohexane ring, nitrogen-containing heteroaromatic ring (for example, pyrrole ring, pyrazole ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring) , Indole ring and isoindole ring) are preferable. In the compound represented by the general formula (I), at least two of R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ are preferably an alkyl group having a ring structure as a substituent. Further, R ²⁶ and R ²⁷ are preferably each independently an alkyl group or an aromatic group. In the compound represented by the general formula (I), the total number of ring structures present in the substituents of R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ is preferably 4 or less.
250-1200 are preferable, as for the molecular weight of the compound represented by general formula (I), 300-800 are more preferable, and 350-600 are more preferable.
Although the specific example of a compound represented by general formula (I) below is shown, it is not limited to these.

The compound represented by the general formula (I) can also be used in the form of hydrate, solvate or salt. The hydrate may contain an organic solvent, and the solvate may contain water.
The compound represented by the formula (I) can be synthesized using a synthesis method of barbituric acid in which a urea derivative and a malonic acid derivative are condensed. Barbituric acid having two substituents on the nitrogen atom can be obtained by heating N, N′-disubstituted urea and malonic chloride, or N, N′-disubstituted urea, malonic acid and acetic anhydride, etc. It is obtained by mixing with an activator and heating. For example, Journal of the American Chemical Society, 61, 1015 (1939), Journal of Medicinal Chemistry, 54, 2409 (2011), Tetrahedron Letters, 29, 40 The method described in International Publication No. 2007/150011 pamphlet and the like can be preferably used.

  The content of the compound B represented by the general formula (I) in the cellulose acylate film is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass with respect to the cellulose acylate, 0.3-5 mass% is further more preferable.

[Compound C]
The compound C contained in the cellulose acylate film of the present invention will be described below.
Compound C is a compound that satisfies the following requirements c1 and c2.
c1: The absolute value ΔSP (1) of the difference between the SP value of Compound B and the SP value of Compound C is 1.0 MPa ^1/2 or more.
c2: The absolute value ΔSP (2) of the difference between the SP value of cellulose acylate and the SP value of compound C is 1.5 MPa ^1/2 or less.
However, SP value represents the value of the solubility parameter measured by the Hoy method.

  Although details are not clear, by satisfying the above requirement c1, in the polarizing plate in which the cellulose acylate film and the polarizer are bonded, the compound B is more easily diffused in the polarizer in a high temperature and high humidity environment. It is believed to stabilize the dye in the polarizer. Moreover, it is thought that by satisfy | filling the said requirement c2, the compound C exists in a film also in a high temperature, high humidity environment, and it contributes to the spreading | diffusion to the polarizer of the compound B.

Whose ASP (1) is preferably not 1.0 MPa ^1/2 or more 2.5 MPa ^1/2 or less, more preferably 1.2 MPa ^1/2 or more 2.2 MPa ^1/2 or less, more preferably 1. 5 MPa ^1/2 or more 2.0MPa is ^1/2 or less, particularly preferably at 1.7 MPa ^1/2 or more 2.0MPa ^1/2 or less, and most preferably 1.8 MPa ^1/2 or more 2.0MPa ^{1 / 2} or less.
Whose ASP (2) is preferably not 0.0 MPa ^1/2 or more 1.5 MPa ^1/2 or less, more preferably 0.0 MPa ^1/2 or more 1.0 MPa ^1/2 or less, more preferably 0. 0MPa is ^1/2 or more 0.8 MPa ^1/2 or less, particularly preferably 0.0 MPa ^1/2 or more 0.6 MPa ^1/2 or less.

The SP value is a solubility parameter value calculated by the Hoy method, and the Hoy method uses POLYMER HANDBOOK FOURTH EDITION (author: Brandrup, J./Brandrup, J. (EDT) / Immergut, EdmundH. ./Abe, Akihiro / Bloch, Daniel R., Publisher: Wiley, Publication Date: May 2003). For example, the SP value of cellulose acylate (substitution degree 2.4) calculated by this calculation method is 23.0 MPa ^1/2 .

  As the compound C, known plasticizers and polymers can be used, and examples thereof include polyester, polyamide, polyacrylic acid, polystyrene, and carbohydrate derivatives, and polyester is particularly preferred from the effect of improving the durability of the polarizing plate.

  The polyester is preferably a polycondensation polyester obtained from a dicarboxylic acid and a diol, and a polycondensation obtained from at least one dicarboxylic acid having an aromatic ring (also called an aromatic dicarboxylic acid) and at least one diol. Polyester is more preferred. That is, a polycondensation polyester containing at least one aromatic dicarboxylic acid residue and at least one diol residue is more preferable.

(Aromatic dicarboxylic acid residue)
In the present specification, the residue is a partial structure of a polycondensed polyester and represents a partial structure derived from a monomer for forming the polycondensed polyester. For example, the dicarboxylic acid residue formed from dicarboxylic acid HOOC-R-COOH (R represents a hydrocarbon group) is -OC-R-CO-.
The content ratio of aromatic dicarboxylic acid residues in the polycondensed polyester (aromatic dicarboxylic acid residue ratio) is preferably 40 mol% or more with respect to all dicarboxylic acid residues contained in the polycondensed polyester, and 50 mol. % Or more is more preferable, and 70 mol% or more is still more preferable.

The aromatic dicarboxylic acid used for forming the aromatic dicarboxylic acid residue may be one type or two or more types. Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid or Examples include 2,6-naphthalenedicarboxylic acid. Phthalic acid, terephthalic acid and isophthalic acid are preferred, phthalic acid and terephthalic acid are more preferred, and terephthalic acid is even more preferred.
The polycondensation polyester preferably contains at least one selected from phthalic acid residues, terephthalic acid residues, and isophthalic acid residues as aromatic dicarboxylic acid residues, more preferably phthalic acid residues and terephthalic acid residues. It contains at least one selected from residues, and more preferably contains a terephthalic acid residue.
The content of the terephthalic acid residue in the dicarboxylic acid residue of the polycondensed polyester is preferably 40 mol% or more, more preferably 50 mol% or more, and further preferably 70 mol% or more. Although the details are not known, by setting the aromatic dicarboxylic acid residue ratio to 40 mol% or more, it has high affinity with cellulose acylate and hardly causes bleed-out in a high-temperature and high-humidity environment. A cellulose acylate film showing anisotropy is obtained.

(Aliphatic dicarboxylic acid residue)
The polycondensed polyester may contain an aliphatic dicarboxylic acid residue in addition to the aromatic dicarboxylic acid residue.
Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid or 1,4- And cyclohexanedicarboxylic acid.
The aliphatic dicarboxylic acid may be used alone or in combination of two or more. When two kinds are used, it is preferable to use succinic acid and adipic acid. When using 1 type, it is preferable to use a succinic acid. This is preferable in terms of compatibility with the cellulose acylate because the average carbon number of the diol residue can be adjusted to a desired value.

(Aliphatic diol residue)
As the diol for forming the polycondensed polyester, an aromatic diol and an aliphatic diol are used, and at least an aliphatic diol is preferably used.
The polycondensed polyester preferably contains an aliphatic diol residue. For example, the diol residue formed from the diol HO—R—OH is —O—R—O—.
The polycondensation polyester preferably contains an aliphatic diol residue having an average carbon number of 2.5 or more and 7.0 or less, more preferably an aliphatic diol residue having an average carbon number of 2.5 or more and 4.0 or less. It is.
Examples of the aliphatic diol for forming the aliphatic diol residue include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1, 2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanedi 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, diethylene glycol, cyclohexanedi There are methanol and the like, and these are preferably used as one or a mixture of two or more together with ethylene glycol. The preferred aliphatic diol is at least one of ethylene glycol, 1,2-propanediol, and 1,3-propanediol, and particularly preferably at least one of ethylene glycol and 1,2-propanediol. . In the polycondensed polyester, a diol residue is formed by the diol used as a raw material.

(End sealing)
The terminal of the polycondensed polyester is in an unsealed state, that is, a hydroxyl group or a carboxyl group, or in a sealed state by reacting a monocarboxylic acid or monoalcohol, that is, an acyl group, an alkoxy group, or an aryloxy group. Preferably there is.
As monocarboxylic acids used for end-capping, acetic acid, propionic acid, butanoic acid, benzoic acid and the like are preferable, acetic acid or propionic acid is more preferable, and acetic acid is most preferable. As monoalcohols used for sealing, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like are preferable, and methanol is most preferable.
The terminal of the polycondensed ester is more preferably a hydroxyl group, an acetyl group, or a propionyl group.

  The polycondensation polyester plasticizer can be synthesized by either a conventional method of polyesterification reaction of diol and dicarboxylic acid or hot melt condensation method by transesterification or interfacial condensation method of acid chloride of these acids and glycols. It can be easily synthesized by the method. Polycondensation esters are described in detail in Koichi Murai, “Plasticizers, Theory and Applications” (Koshobo Co., Ltd., published on the first edition, March 1, 1973). These compounds are used. You can also

  The weight average molecular weight of the polycondensed polyester is preferably 800 or more, more preferably 800 to 2000, still more preferably 800 to 1500, and particularly preferably 1000 to 1200.

0.5-10 mass% is preferable with respect to a cellulose acylate, as for the content rate of polycondensation polyester, 1-10 mass% is more preferable, and 2-8 mass% is further more preferable.
The acid value of the polycondensed polyester is preferably less than 1 mgKOH / g. The acid value of the polycondensed ester can be measured by the same method as that for the organic acid.

[Cellulose acylate]
Next, the cellulose acylate contained in the cellulose acylate film of the present invention will be described.
Cellulose acylate is an ester of cellulose and carboxylic acid, and the carboxylic acid is preferably a fatty acid having 2 to 22 carbon atoms, more preferably cellulose acylate being a lower fatty acid having 2 to 4 carbon atoms, Most preferred is cellulose acetate having 2 carbon atoms.

  Examples of cellulose as a cellulose acylate raw material include cotton linter and wood pulp (hardwood pulp, conifer pulp). Cellulose acylate obtained from any raw material cellulose can be used, and in some cases, it may be used as a mixture. 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) can be used, and the cellulose acylate film of the present invention is not particularly limited.

  In cellulose acylate, an acyl group is substituted on the hydroxyl group of cellulose, and the acyl group preferably has 2 to 22 carbon atoms. The acyl group having 2 to 22 carbon atoms may be an aliphatic acyl group or an aromatic acyl group, and may be one kind or a mixture of two or more kinds. They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, or aromatic alkyl carbonyl esters of cellulose, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl I-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred. Further preferred groups are an acetyl group and propionyl, and the most preferred group is an acetyl group.

The degree of polymerization of cellulose acylate is preferably 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferable, 180 to 400 is still more preferable, and 180 to 350 is particularly preferable. The viscosity average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method {Kazuo Uda, Hideo Saito, "Journal of the Textile Society," Vol. 18, No. 1, pages 105-120 (1962)}. This method is also described in detail in JP-A-9-95538.
Molecular weight distribution of cellulose acylate was evaluated using HLC-8220 (manufactured by Tosoh Corporation) and TSKgel (registered trademark) Super AWM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15.0 cm) as a column. The eluent is an NMP solution containing 10 mmol / L of lithium bromide, preferably having a low polydispersity index Mw / Mn (Mw is the weight average molecular weight, Mn is the number average molecular weight) and a narrow molecular weight distribution. The typical Mw / Mn value is preferably 1.0 to 4.0, more preferably 2.0 to 4.0, and most preferably 2.3 to 3.4. .

(Acyl group substitution degree of cellulose acylate)
The cellulose acylate used in the present invention is one in which the hydroxyl group of cellulose is acylated. For the measurement of the substitution degree of the acyl group to the hydroxyl group of cellulose, acetic acid and / or 3 to 3 carbon atoms are substituted for the hydroxyl group of cellulose. The degree of substitution of 22 fatty acids can be measured and the degree of substitution can be obtained by calculation. As a measuring method, it can carry out according to ASTM D-817-91.

  The cellulose acylate film of the present invention comprises a cellulose acylate having an average acyl group substitution degree of 2.00 or more and less than 2.65. When the average acyl group substitution degree of cellulose acylate is 2.00 or more, it is preferable from the viewpoint of polarizing plate durability and humidity dimensional change, and is preferably less than 2.65 from the viewpoint of optical properties. The average acyl group substitution degree of the rate is preferably 2.2 or more and 2.6 or less, and more preferably 2.3 or more and 2.5 or less.

  The content of cellulose acylate is preferably 60 to 90% by mass, more preferably 70 to 85% by mass, and 75 to 80% by mass with respect to the total mass of the cellulose acylate film. Further preferred.

[Other additives]
In the present invention, a known additive can be used as an additive for the cellulose acylate film. Specifically, an Rth control agent, an anti-degradation agent, an ultraviolet inhibitor, a peeling accelerator, a plasticizer, an infrared absorber, Matting agents and the like can be mentioned.

  The thickness of the cellulose acylate film is preferably 54 to 20 μm, more preferably 50 to 23 μm, and still more preferably 45 to 35 μm.

  The Rth of the cellulose acylate film is preferably 110 to 130 nm, more preferably 114 to 126 nm, and still more preferably 118 to 122 nm.

In the cellulose acylate film of the present invention, Rth / d is 2.2 [nm / μm] or more and less than 5.5 [nm / μm]. Rth / d indicates a value obtained by dividing Rth by d, Rth is a retardation [unit: nm] in the film thickness direction of the cellulose acylate film at a wavelength of 590 nm, and d is a film thickness [unit: μm] of the cellulose acylate film. ].
When the Rth / d of the cellulose acylate film is 2.2 [nm / μm] or more and less than 5.5 [nm / μm], the thinness of the entire film and the light leakage at the time of black display of the liquid crystal display device are reduced. It is preferable from the viewpoint. The Rth / d of the cellulose acylate film is preferably 2.4 [nm / μm] or more and 4.0 [nm / μm] or less, and preferably 2.6 [nm / μm] or more and 3.4 [nm]. / Μm] or less.

  The aspect of the cellulose acylate film of the present invention is produced not only in the form of a film piece cut to a size that can be incorporated into a liquid crystal display device as it is, but also produced in a long form by continuous production and wound up into a roll. Also included are cellulose acylate films of the above-described embodiments (for example, embodiments having a roll length of 2500 m or more or 3900 m or more).

[Method for producing cellulose acylate film]
The cellulose acylate film of the present invention can be produced according to a known method, and is a polymer solution containing cellulose acylate having an average acyl group substitution degree of 2.0 or more and less than 2.65, a solvent, and compounds A, B, and C. It is preferable to include a step of forming the film into a film and a step of stretching the film. These details will be described below.

As a method for producing a cellulose acylate film, a film containing cellulose acylate can be formed using a solution casting film forming method or a melt film forming method. From the viewpoint of improving the surface shape of the film, the method for producing a cellulose acylate film preferably includes a step of forming a film containing cellulose acylate by solution casting.
Hereinafter, although the case where the solution casting film forming method is used will be described as an example, the method for producing the cellulose acylate film is not limited to the solution casting film forming method. In addition, about the case where the said melt film forming method is used as a manufacturing method of a cellulose acylate film, a well-known method can be used.

<< Dope >>
A dope (cellulose acylate solution) can be produced by dissolving cellulose acylate in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain.
Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone (MEK), diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Moreover, 2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol can also be used as an organic solvent having two or more types of functional groups. The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and the halogen of the halogenated hydrocarbon is preferably chlorine. Methylene chloride is a typical halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

The cellulose acylate solution can be produced by a method of treating at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solution casting film forming method.
The amount of cellulose acylate is preferably adjusted so that it is contained in an amount of 10 to 40% by mass in the resulting solution. The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, it is preferable that cellulose acylate and an organic solvent are placed in a pressure vessel and sealed, and stirred while being heated to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 120 ° C., and more preferably 80 to 110 ° C. The concentration of the dope before casting is preferably adjusted so that the solid content is 15 to 30% by mass. Regarding casting and drying methods in the solution casting film forming method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,273,069, 2,273,070, British Patent 640731, 736892, JP-B 45-4554, 49-5614, JP-A-60-176834, 60-203430, 62-1215035 .

<< Process for fluent dope solution >>
The obtained dope may be cast as a single-layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate solutions of two or more layers may be cast.
When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, JP-A-11-198285 and the like can be applied. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferable aspect that the surface side solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution. .

In the case of co-casting, the thickness of the inner layer (core layer) and the surface layer (skin layer) is not particularly limited, but preferably the surface layer is 1 to 50% of the total film thickness. The thickness is preferably 2 to 30%. Here, in the case of co-casting of three or more layers, the total thickness of the outermost layer in contact with the casting metal support and the outermost layer in contact with the air side is defined as the thickness of the surface layer.
In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different average acyl group substitution degrees.

<< Step of drying film >>
The drying is generally performed on the surface side of the metal support (drum or belt), that is, the web on the metal support (the dope film after casting the dope on the metal support is also referred to as “web”). The method of applying hot air from the surface of the drum, the method of applying hot air from the back of the drum or belt, bringing the temperature-controlled liquid into contact with the back of the belt or the opposite side of the dope casting surface of the drum, and transferring the drum or belt by heat transfer There is a backside liquid heat transfer method that controls the surface temperature by heating. In particular, the back surface liquid heat transfer method is preferable.
The drying temperature is preferably 80 ° C to 160 ° C, and more preferably 100 to 140 ° C. The drying time is preferably 5 minutes to 1 hour, more preferably 10 minutes to 30 minutes.

<< Step of stretching film >>
It is preferable from the viewpoint of Rth expression that the film after drying is stretched at a temperature of “glass transition temperature (Tg) −20 ° C.” or higher. The stretching direction of the film of the present invention is preferably either the film transport direction or the direction (width direction) perpendicular to the transport direction.
Methods for stretching in the width direction are described in, for example, JP-A-62-115035, JP-A-4-152125, JP-A-2842211, JP-A-298310, and JP-A-11-48271. Yes. In the case of stretching in the longitudinal direction, for example, the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film peeling speed. In the case of stretching in the width direction, the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter. After the film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
The stretch ratio of the cellulose acylate film of the present invention is preferably 5% to 200%, more preferably 10% to 100%.
Here, the “stretch ratio (%)” means that obtained by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching

[Polarizer]
The polarizing plate of the present invention has at least one cellulose acylate film of the present invention and a polarizer. The polarizing plate of the present invention is preferably a polarizing plate having a polarizer and two protective films protecting both surfaces of the polarizer, and at least one of the protective films is the cellulose acylate film of the present invention. is there. As the other polarizing plate protective film, a known cellulose acylate film, acrylic film, or polyester film can be used.
The polarizing plate of the present invention is excellent in polarizing plate durability.
A laminate (measurement sample) was prepared by sticking the polarizing plate of the present invention on glass so that the cellulose acylate film of the present invention is on the glass side via an adhesive, and JASCO Corporation The orthogonal transmittance was measured using an automatic polarizing film measuring apparatus VAP-7070. The transmittance measured after leaving for 2 hours in an environment of temperature 25 ° C. and relative humidity 60% is defined as the orthogonal transmittance (T1), and then left for 200 hours in an environment of temperature 90 ° C. and relative humidity 90%. The transmittance measured in step 4 is defined as orthogonal transmittance (T2), and the durability of the polarizer calculated from the following formula is preferably 15% or less, more preferably 14% or less, and 13% or less. More preferably, it is particularly preferably 12% or less.
Polarizing plate durability = T2-T1

  The cellulose acylate film of the present invention is preferably used as a polarizing plate protective film (inner side film) on the liquid crystal cell side of the polarizer.

Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. In general, iodine-based polarizers and dye-based polarizers can be produced using polyvinyl alcohol-based films.
Like the cellulose acylate film of the present invention, the polarizing plate of the present invention is not only a polarizing plate of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also by continuous production. Also included is a polarizing plate in an aspect (for example, an aspect having a roll length of 2500 m or more or 3900 m or more) that is produced in a long shape and wound up in a roll shape. In order to use for a large-screen liquid crystal display device, the width of the polarizing plate is preferably 1330 mm or more.
In the polarizing plate of this invention, it is preferable that the film thickness of a polarizer is 3-25 micrometers, and it is more preferable that it is 5-20 micrometers.
The total thickness of the polarizing plate of the present invention is preferably 40 to 180 μm, more preferably 45 to 160 μm, and particularly preferably 50 to 150 μm. Here, the total thickness is a thickness including a polarizer, a polarizing plate protective film bonded to both sides of the polarizer, and an adhesive layer for bonding the polarizing plate protective film.
The specific configuration of the polarizing plate of the present invention is not particularly limited, and a known configuration can be employed. For example, the configuration described in FIG. 6 of JP-A-2008-262161 can be employed.

[Liquid Crystal Display]
The liquid crystal display device of the present invention includes a liquid crystal cell and the cellulose acylate film or polarizing plate of the present invention. Further, it is a liquid crystal display device including a liquid crystal cell and two polarizing plates disposed on both sides thereof, and at least one of the two polarizing plates is more preferably the polarizing plate of the present invention.
In the liquid crystal display device, the cellulose acylate film of the present invention is particularly preferably disposed on the liquid crystal cell side of the polarizer of at least one polarizing plate.
The cellulose acylate film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. As the liquid crystal cell, TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal Crystal), AFLC (Anti-Ferroelectric LiquidN Crystal, OCB (Optic LiquidTypical). Various display modes such as (Vertical Aligned) and HAN (Hybrid Aligned Nematic) have been proposed.
In the liquid crystal display device of the present invention, the liquid crystal cell is preferably a VA mode or TN mode liquid crystal cell, and more preferably a VA mode liquid crystal cell. The cellulose acylate film of the present invention has optical characteristics particularly suitable for a liquid crystal display device having a VA mode liquid crystal cell, thereby contributing to an improvement in display performance.

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

(Preparation of cellulose acylate)
Cellulose acylate was synthesized by the method described in JP-A-10-45804 and 08-231761, and the acyl group substitution degree was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, and carboxylic acid (acetic acid) as an acyl group raw material was added, and an acylation reaction was performed at 40 ° C. At this time, the substitution degree of the acyl group (acetyl group) was adjusted by adjusting the amount of carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Furthermore, the low molecular weight component of the cellulose acylate (cellulose acetate) was removed by washing with acetone to obtain cellulose acylates having various average acyl group substitution degrees.

<Synthesis of Compounds A1, A2, A3, A4, A5>
Compounds A1, A2, A3, A4, and A5 used as Compound A were synthesized by a method similar to or similar to the method described in International Publication No. 2015/151683. The structural formulas of the synthesized compounds are shown in Table 1 below.

<Synthesis of Compounds B1, B3, B5, B6, B21, B22, B25>
Compounds B1, B3, B5, B6, B21, B22 and B25 used as Compound B were synthesized by a method similar to or similar to the method described in International Publication No. 2015/005398. The structural formula and SP value (unit: MPa ^1/2) of the synthesized compound are shown in Table 2 below.

The compounds used as Compound C are shown below. Table 3 shows the dicarboxylic acids and diols used in the synthesis of the polycondensation polyester used as compound C, the molar ratios of them, and the SP value (unit: MPa ^1/2) of each compound. Ac represents an acetyl group.

  Bz represents a benzoyl group.

  The compounds used in the comparative examples are shown below.

[Example 1]
<Preparation of dope for forming core layer>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a dope for forming a core layer.
(Composition of dope for core layer formation)
Cellulose acetate (substitution degree 2.4) 100 parts by mass A1 (additive (1)) 20 parts by mass B6 (additive (2)) 2.0 parts by mass C2 (additive (3)) 0 parts by mass-392 parts by mass of methylene chloride-58.5 parts by mass of methanol

<Preparation of dope for skin layer formation>
The following composition was placed in a mixing tank and stirred to dissolve the cellulose acetate to prepare a dope for forming a skin layer.
(Composition of dope for skin layer formation)
-Cellulose acetate (substitution degree 2.8) 100 parts by mass-Methylene chloride 440 parts by mass-Methanol 65.8 parts by mass

<Preparation of cellulose acylate film>
Using a band casting apparatus, the prepared core layer forming dope and skin layer forming dope were co-cast in three layers so that the skin layer, the core layer, and the skin layer were laminated in this order. The thickness of the core layer after drying was 39 μm, and the thickness of each skin layer was 1 μm. The obtained film (web) was peeled from the band, sandwiched between clips, and when the amount of residual solvent relative to the mass of the entire film was 20 to 5% by mass, using a tenter, the draw ratio was 1.08 times at 140 ° C. The film was transversely stretched (stretched in the width direction). Then, after removing the clip from the film and drying at 140 ° C. for 20 minutes, the cellulose acylate film was further stretched transversely at a stretch ratio of 1.15 times at Tg (glass transition temperature) −5 ° C. of the film using a tenter. Was made. The film thickness of the obtained cellulose acylate film was 40 μm.
The “stretch ratio (%)” means that obtained by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching Note that the loss tangent tan δ determined by dynamic viscoelasticity measurement is Tg. Temperature. The loss tangent tan δ is as follows for a film sample conditioned for 2 hours or more in an atmosphere of a temperature of 25 ° C. and a relative humidity of 60% using a dynamic viscoelasticity measuring device (DVA-200 manufactured by IT Measurement Control Co., Ltd.) , E ″ (loss elastic modulus) and E ′ (storage elastic modulus) were measured, tan δ (= E ″ / E ′) and its maximum value were determined, and Tg was measured.
Apparatus: DVA-200 manufactured by IT Measurement Control Co., Ltd.
Sample: 5 mm, length 50 mm (gap 20 mm)
Measurement conditions: Tensile mode
Measurement temperature: -25 ° C to 220 ° C
Temperature rising condition: 5 ℃ / min
Frequency: 1Hz
Moreover, the residual solvent amount was calculated | required according to the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of the web at an arbitrary point, and N is the mass when the web of which M is measured is dried at 120 ° C. for 2 hours.

[Examples 2 to 25, Comparative Examples 1 to 17]
Cellulose acylate, type of additive (1), type of additive (2), type of additive (3), and inclusion of additive (1), additive (2), and additive (3) Cellulose acylate films of Examples 2 to 25 and Comparative Examples 1 to 17 were produced in the same manner as in Example 1 except that the rate was changed as shown in Table 6 below.
In Table 6 below, the contents of additive (1), additive (2), and additive (3) are additive (1) and additive relative to cellulose acylate in each cellulose acylate film. The content (mass)% of (2) and additive (3).

  Each cellulose acylate film produced in Examples and Comparative Examples was evaluated as follows.

<Rth / d>
The film thickness (d unit: μm) of the produced cellulose acylate film was measured using a high-precision digital length measuring machine (VL-50-B) manufactured by Mitutoyo Corporation.
For each cellulose acylate film, Rth (unit: nm) was measured by the method described above.
The value of Rth / d was calculated from the obtained value and is shown in Table 6 below.

<Change in humidity dimension>
A film sample having a length of 12 cm (measurement direction) and a width of 3 cm is cut out in a direction parallel to the slow axis direction of each cellulose acylate film, pin holes are formed at intervals of 10 cm in parallel with the longitudinal direction of the sample, and a temperature of 25 ° C. After holding for 2 hours in an environment with a relative humidity of 60%, the interval between the pin holes is measured with a pin gauge, and the measured value is L60. Next, after adjusting the humidity for 24 hours in an environment of a temperature of 25 ° C. and a relative humidity of 10%, the interval between the pin holes is measured with a pin gauge, and the measured value is L10. The humidity dimensional change rate is calculated by the following formula using these measured values.
Humidity dimensional change rate [%] = | L60−L10 | / L60

<Preparation of polarizing plate>
Each cellulose acylate film was bonded to a polyvinyl alcohol polarizer using an adhesive. Fujitac (registered trademark) TD80 (manufactured by FUJIFILM Corporation) was bonded to the opposite surface of the polarizer (the surface on which the cellulose acylate film was not bonded) to produce a polarizing plate.

<Polarizing plate durability>
About the polarizing plate of each Example produced above and the comparative example, the orthogonal transmittance | permeability of the polarizer in wavelength 410nm was measured using JASCO Corporation automatic polarizing film measuring apparatus VAP-7070. The transmittance measured after leaving for 2 hours in an environment of temperature 25 ° C. and relative humidity 60% is defined as the orthogonal transmittance (T1), and then left for 200 hours in an environment of temperature 90 ° C. and relative humidity 90%. The transmittance measured in step 1 was defined as the orthogonal transmittance (T2), and the polarizing plate durability was calculated from the following formula.
Polarizing plate durability = T2-T1

From the said Table 6, the cellulose acylate film of an Example was excellent in the optical characteristic with respect to the cellulose acylate film of the comparative example, and there were few humidity dimensional changes. In addition, the polarizing plate produced using the cellulose acylate film of the example as a polarizing plate protective film is higher in temperature than the polarizing plate produced using the cellulose acylate film of the comparative example as a polarizing plate protective film. The polarizing plate was excellent in durability in a wet environment.
Further, from Example 4 and Comparative Examples 13 to 15, when compound C alone was added to the cellulose acylate film (Comparative Example 14) containing Compound A and not containing Compounds B and C (Comparative Example 13). ), It can be seen that the durability of the polarizing plate does not improve but rather decreases. Moreover, it turns out that polarizing plate durability improves significantly by adding both the compound B and the compound C compared with the case where only the compound B is added (comparative example 15) (Example 4).

Claims (8)

Cellulose acylate having an average acyl group substitution degree of 2.00 or more and less than 2.65;
Compound A satisfying the following requirements a1 and a2,
Compound B represented by the following general formula (I):
Compound C satisfying the following requirements c1 and c2,
Containing
A cellulose acylate film having an Rth / d of 2.2 or more and less than 5.5.
Rth / d indicates a value obtained by dividing Rth by d, Rth is a retardation [unit: nm] in the film thickness direction of the cellulose acylate film at a wavelength of 590 nm, and d is a film thickness [unit: μm] of the cellulose acylate film. ].
a1: At least one structure represented by —C (═O) —NH—Ar is present in the molecule. Ar represents an unsubstituted aromatic ring.
a2: The value obtained by dividing the molecular weight of Compound A by the number of aromatic rings contained in the molecule of Compound A is 220 or less.
Formula (I)

In general formula (I), R ²⁶ represents an alkyl group, an alkynyl group or an aromatic hydrocarbon group, and R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aromatic hydrocarbon group or an aromatic group. Represents a heterocyclic group, and R ²⁹ represents a hydrogen atom, an alkyl group or an aromatic hydrocarbon group. R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ may each independently have a substituent.
c1: The absolute value ΔSP (1) of the difference between the SP value of Compound B and the SP value of Compound C is 1.0 MPa ^1/2 or more.
c2: The absolute value ΔSP (2) of the difference between the SP value of cellulose acylate and the SP value of compound C is 1.5 MPa ^1/2 or less.
However, SP value represents the value of the solubility parameter measured by the Hoy method.   The cellulose acylate film according to claim 1, wherein the content of the compound A is 15% by mass or more and 30% by mass or less with respect to the total mass of the cellulose acylate. The cellulose acylate film according to claim 1 or 2, wherein the compound A is a compound represented by the following general formula (J).
Formula ^{(J): Z- (L 12} -L 11 -O-C (= O) -NH-Ar) n1
In general formula (J), Ar represents an unsubstituted aromatic ring. L ¹¹ represents a single bond or an alkylene group, and the alkylene group may have a substituent. L ¹² represents a single bond or a linking group selected from linking groups consisting of —O—, —NR ¹ —, —S—, —C (═O) —, and combinations thereof. R ¹ represents a hydrogen atom or a substituent. Z represents an n1-valent group. n1 represents an integer of 1 to ^6, if L ^{11, L 12} and Ar there are a plurality, a plurality of ^{L 11, L 12} and Ar may be the same or different from each other. The cellulose acylate film according to claim 3, wherein the total molecular weight of L ¹¹ , L ¹² , and Z is 40 or more and 100 or less.   The cellulose acylate film according to claim 1, wherein the compound C is a polyester having a weight average molecular weight of 800 or more.   The cellulose acylate film according to claim 1, wherein a content of the compound C is 0.1% by mass or more and 10% by mass or less with respect to a total mass of the cellulose acylate.   The polarizing plate which has a cellulose acylate film of any one of Claims 1-6.   A liquid crystal display device comprising the polarizing plate according to claim 7.