JP5741850B2 - Optical film, polarizing plate including the same, and liquid crystal display device - Google Patents

Description

  The present invention relates to an optical film, a polarizing plate including the optical film, and a liquid crystal display device.

  Resin films such as cellulose ester, polycarbonate, and polyolefin are optical films; mainly used as optical compensation films for liquid crystal display devices. Among them, a resin film containing a cellulose ester (hereinafter also simply referred to as a cellulose ester film) is widely used because it can be easily bonded to a polyvinyl alcohol film that is a polarizer.

  In recent years, development of thin and light notebook computers and thin and large-screen TVs has been progressing. Along with this, there is an increasing demand for thinner, larger and higher performance optical compensation films for liquid crystal display devices. However, the cellulose ester film has not only sufficient birefringence essential for the optical compensation film, but also has high hygroscopicity, and therefore has low humidity stability.

  As means for solving these problems, an optical compensation film containing a discotic compound has been proposed (for example, Patent Document 1). However, the optical compensation film containing the discotic compound has insufficient retardation. Moreover, when the addition amount of the discotic compound is increased in order to develop a desired retardation, bleed out may occur.

  An optical compensation film containing a 1,3,5-triazine compound capable of forming a molecular complex has been proposed as a means for improving retardation development while suppressing bleed out (for example, Patent Document 2). Although the optical compensation film containing these compounds suppresses bleed-out, there is a problem that the retardation tends to vary depending on the humidity of the use environment. Therefore, the polarizing plate and the liquid crystal display device including the optical compensation film have a problem that the moisture resistance is not sufficient.

  As a means for improving the humidity dependency of the optical compensation film, a compound in which an amino group is bonded to a carbon atom constituting a 1,3,5-triazine ring, or an amide at the second and fourth carbon atoms constituting a pyrimidine ring. A film containing a compound having a group bonded thereto has been proposed (for example, Patent Documents 3 and 4).

JP 2001-166144 A JP 2004-109410 A JP 2011-94114 A JP 2011-94120 A

  However, although the film containing the compounds described in Patent Documents 3 and 4 is improved in humidity dependency, there is a problem that retardation developability is low or retardation is lowered. Thus, there is a demand for a cellulose ester film having a high retardation, a small fluctuation of the retardation due to the temperature and humidity of the use environment (high heat-and-moisture resistance), and a good brittleness (slitting suitability). ing.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical film having a high retardation, a high heat-and-moisture resistance property, and brittleness. It is another object of the present invention to provide a polarizing plate including the optical film and having good light resistance and heat-and-moisture resistance, and a liquid crystal display device with reduced front contrast unevenness and humidity dependency of the viewing angle.

（式中、
Ｌ_１１は、単結合または−ＮＲ_１−（Ｒ_１は、水素原子、炭素数１〜６のアルキル基またはアリール基）を表し；
Ａ_１１は、アリール含有基またはヘテロアリール含有基を表し；
Ｌ_１２は、単結合、−ＮＲ_２−（Ｒ_２は、水素原子、炭素数１〜６のアルキル基またはアリール基）、−Ｏ−、−Ｓ−、−Ｃ（＝Ｏ）−、−ＮＲ_４Ｃ（＝Ｏ）−（Ｒ_４は、水素原子、炭素数１〜６のアルキル基またはアリール基）または−ＳＯ_２−を表し；
Ａ_１２は、アリール含有基、ヘテロアリール含有基またはシクロアルキル基を表し；
Ｌ_１３は、単結合、−ＮＲ_３−（Ｒ_３は、水素原子、炭素数１〜６のアルキル基またはアリール基）、−Ｏ−、−Ｓ−、−Ｃ（＝Ｏ）−、−ＮＲ_５Ｃ（＝Ｏ）−（Ｒ_５は、水素原子、炭素数１〜６のアルキル基またはアリール基）または−ＳＯ_２−を表し；
Ａ_１３は、アリール含有基、ヘテロアリール含有基、シクロアルキル基または水素原子を表し；
Ｒ_１２は、水素原子、ヒドロキシル基、炭素数１〜６のアルキル基、アリール基またはアシルアミノ基を表す）
［２］ 前記一般式（１）のＡ_１１、Ａ_１２およびＡ_１３において、前記アリール含有基は、アリール基、アリール含有アルキル基またはアリール含有アルケニル基であり；前記ヘテロアリール含有基は、ヘテロアリール基、ヘテロアリール含有アルキル基またはヘテロアリール含有アルケニル基である、［１］に記載の光学フィルム。
［３］ 前記一般式（１）のＡ_１３は、アリール含有基、ヘテロアリール含有基またはシクロアルキル基である、［１］または［２］に記載の光学フィルム。
［４］ 前記セルロースエステルは、下記式（ａ）および（ｂ）を満たす、［１］〜［３］のいずれかに記載の光学フィルム。
式（ａ） １．５≦Ｘ＋Ｙ≦２．５
式（ｂ） ０≦Ｙ≦１．５
（式中、Ｘはアセチル基の置換度、Ｙはプロピオニル基またはブチリル基、もしくはそれらの混合物の置換度を表す）
［５］ 前記セルロースエステルにおいて、前記式（ｂ）のＹが０である、［４］に記載の光学フィルム。
［６］ 前記光学フィルムの厚みが２０〜６０μｍである、［１］〜［５］のいずれかに記載の光学フィルム。
［７］ 下記式（Ｉ）で表される、波長５９０ｎｍでのリターデーションＲｏが２０〜１５０ｎｍであり、かつ下記式（II）で表される、波長５９０ｎｍでのＲｔｈが７０〜３００ｎｍである、［１］〜［６］のいずれかに記載の光学フィルム。
式（Ｉ） Ｒｏ＝（ｎｘ−ｎｙ）×ｄ
式（II） Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ
（ｎｘは、光学フィルムの面内方向において屈折率が最大になる方向ｘにおける屈折率を表し；ｎｙは、光学フィルムの面内方向において前記方向ｘと直交する方向ｙにおける屈折率を表し；ｎｚは、光学フィルムの厚み方向ｚにおける屈折率を表し；ｄ（ｎｍ）は、光学フィルムの厚みを表す） [1] An optical film containing a cellulose ester and a compound represented by the following general formula (1).
General formula (1)

(Where
L ₁₁ represents a single bond or —NR ₁ — (R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group);
A ₁₁ represents an aryl-containing group or a heteroaryl-containing group;
L ₁₂ is a single bond, —NR ₂ — (R ₂ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group), —O—, —S—, —C (═O) —, —NR ₄ C (═O) — (R ₄ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group) or —SO ₂ —;
A ₁₂ represents an aryl-containing group, heteroaryl-containing group or cycloalkyl group;
L ₁₃ is a single bond, —NR ₃ — (R ₃ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group), —O—, —S—, —C (═O) —, —NR ₅ C (═O) — (R ₅ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group) or —SO ₂ —;
A ₁₃ represents an aryl-containing group, a heteroaryl-containing group, a cycloalkyl group, or a hydrogen atom;
R ₁₂ represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an aryl group or an acylamino group)
[2] In A ₁₁ , A ₁₂ and A ₁₃ of the general formula (1), the aryl-containing group is an aryl group, an aryl-containing alkyl group or an aryl-containing alkenyl group; the heteroaryl-containing group is heteroaryl The optical film according to [1], which is a group, a heteroaryl-containing alkyl group, or a heteroaryl-containing alkenyl group.
[3] The optical film according to [1] or [2], wherein A _{13 in the} general formula (1) is an aryl-containing group, a heteroaryl-containing group, or a cycloalkyl group.
[4] The optical film according to any one of [1] to [3], wherein the cellulose ester satisfies the following formulas (a) and (b).
Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(Wherein X represents the degree of substitution of the acetyl group, Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof)
[5] The optical film according to [4], wherein Y in the formula (b) is 0 in the cellulose ester.
[6] The optical film according to any one of [1] to [5], wherein the optical film has a thickness of 20 to 60 μm.
[7] Retardation Ro at a wavelength of 590 nm represented by the following formula (I) is 20 to 150 nm, and Rth at a wavelength of 590 nm represented by the following formula (II) is 70 to 300 nm. The optical film according to any one of [1] to [6].
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the optical film; ny represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the optical film; nz Represents the refractive index in the thickness direction z of the optical film; d (nm) represents the thickness of the optical film)

[8] A polarizing plate having a polarizer and the optical film according to any one of [1] to [7] disposed on at least one surface of the polarizer.
[9] A liquid crystal display device including a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell, wherein at least one of the pair of polarizing plates is a polarizer and at least one of the polarizers. A liquid crystal display device comprising the optical film according to any one of [1] to [7] disposed on a surface.
[10] The liquid crystal display device according to [9], wherein the optical film is disposed on a surface of the polarizer on the liquid crystal cell side.
[11] The liquid crystal cell includes a pair of opposing transparent substrates and a liquid crystal layer that is sandwiched between the pair of transparent substrates and includes a positive liquid crystal, and one of the pair of transparent substrates. A plurality of electrodes for applying a voltage to the positive type liquid crystal is disposed on the transparent substrate, and the positive type liquid crystal is aligned perpendicular to the transparent substrate when no voltage is applied, and when the voltage is applied, the plurality of electrodes are arranged. The liquid crystal display device according to [9] or [10], wherein the liquid crystal display device is aligned horizontally with respect to the transparent substrate by an electric field generated between the electrodes.

  The optical film of the present invention has high retardation, and has high heat and humidity resistance and brittleness. Therefore, the polarizing plate including the optical film of the present invention has good light resistance and moisture and heat resistance, and the liquid crystal display device can reduce the front contrast unevenness and the humidity dependence of the viewing angle.

It is a schematic diagram which shows the basic composition of one Embodiment of the liquid crystal display device which concerns on this invention.

1. Optical film The optical film of this invention contains a cellulose ester and the compound represented by General formula (1).

Cellulose ester The cellulose ester is not particularly limited, but may be a compound obtained by esterifying cellulose with an aliphatic carboxylic acid or an aromatic carboxylic acid having about 2 to 22 carbon atoms. The aliphatic carboxylic acid may be a linear or branched aliphatic carboxylic acid, may have a ring, and may further have a substituent. The cellulose ester is particularly preferably a compound obtained by esterifying cellulose with a lower fatty acid having 6 or less carbon atoms.

  In addition to cellulose acetate, preferred examples of cellulose esters include cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate and the like of cellulose containing propionate group or butyrate group in addition to acetyl group. Mixed fatty acid esters are included.

The cellulose ester preferably has a total acyl group substitution degree of 1.5 or more and 2.5 or less, and more preferably satisfies the following formulas (a) and (b).
Formula (a) 2.0 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(Wherein, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof)

Of these, cellulose acetate (Y = 0) and cellulose acetate propionate (Y> 0 and Y: propionyl group) are particularly preferable. As the cellulose acetate propionate, those that simultaneously satisfy the following formulas (a), (b1) and (c1) are particularly preferable.
Formula (a) 2.0 ≦ X + Y ≦ 2.5
Formula (b1) 0.1 ≦ Y ≦ 1.5
Formula (c1) 1.0 ≦ X ≦ 2.4

  The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The cellulose ester may be a mixture of a plurality of types of cellulose esters having different degrees of substitution in order to obtain desired optical properties. The mixing ratio in a mixture of two types of cellulose esters having different degrees of substitution is preferably 10:90 to 90:10 by mass ratio.

The number average molecular weight of the cellulose ester is preferably in the range of 6 × 10 ^{4 to} 3 × 10 ^{5 and in} the range of 7 × 10 ⁴ to 2 × 10 ⁵ in order to obtain a film having high mechanical strength. It is more preferable. The number average molecular weight of the cellulose ester can be measured by gel permeation chromatography (GPC).

The measurement conditions are as follows.
Solvent: Methylene chloride Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used.
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 1.0 × 10 ^{6 to} 5.0 × 10 ² 13 calibration curves are used. The 13 samples are preferably selected at approximately equal intervals.

  Cellulose esters can be synthesized by known methods. Specifically, it can be synthesized by esterifying cellulose with an organic acid having 3 or more carbon atoms or acetic anhydride containing at least acetic acid or acetic anhydride (described in JP-A-10-45804). See how).

  As the raw material cellulose, for example, cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf and the like can be used. The cellulose used as a raw material may be only one type or a mixture of two or more types.

About the compound represented by the general formula (1) The compound represented by the general formula (1) can preferably function as a retardation developer.
General formula (1)

L _{11 in the} general formula (1) represents a single bond or —NR ₁ —, preferably —NR ₁ —. R ₁ in —NR ₁ — is a hydrogen atom, an alkyl group or an aryl group, preferably a hydrogen atom. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group and the like. The number of ring carbon atoms of the aryl group is preferably 6 to 10, and more preferably 6. Examples of the aryl group having 6 to 10 ring carbon atoms include a phenyl group and a naphthyl group.

A _{11 in the} general formula (1) represents an aryl-containing group or a heteroaryl-containing group.

  The aryl-containing group is an aryl group, an aryl-containing alkyl group or an aryl-containing alkenyl group. The ring carbon number of the aryl group is preferably 6 to 14, and more preferably 6. Examples of the aryl group having 6 to 14 ring carbon atoms include a phenyl group, a naphthyl group, and an anthranyl group, preferably a naphthyl group or a phenyl group, and more preferably a phenyl group.

  The aryl-containing alkyl group is an alkyl group containing an aryl group, and the aryl group and the alkyl group may be directly bonded, or the aryl group and the alkyl group are other divalent groups (for example, —NH— Etc.). The alkyl group in the aryl-containing alkyl group preferably has 1 to 10 carbon atoms, and more preferably 2 to 6 carbon atoms. Examples of the aryl-containing alkyl group include a phenylmethyl group and a phenylethyl group.

  The aryl-containing alkenyl group is an alkenyl group containing an aryl group, and the aryl group and the alkenyl group may be directly bonded, or the aryl group and the alkenyl group may be another divalent group (for example, —NH— Etc.). The carbon number of the alkenyl group in the aryl-containing alkenyl group is preferably 2 to 10, and more preferably 2 to 6. Examples of the aryl-containing alkenyl group include a phenylethylenyl group.

  A heteroaryl-containing group is a heteroaryl group, a heteroaryl-containing alkyl group, or a heteroaryl-containing alkenyl group. Examples of heteroaryl groups include pyridyl group, pyrimidyl group, thiazolyl group, oxazolyl group, imidazolyl group, benzothiazolyl group, benzooxazolyl group, benzoimidazolyl group, etc., preferably pyridyl group, pyrimidyl group, benzoxazolyl group. Group, benzothiazolyl group, benzoimidazolyl group, more preferably pyridyl group, benzoxazolyl group or benzothiazolyl group.

  The heteroaryl-containing alkyl group is an alkyl group containing a heteroaryl group, and the heteroaryl group and the alkyl group may be directly bonded, or the heteroaryl group and the alkyl group may be another divalent group ( For example, -NH- etc. may be couple | bonded. The alkyl group in the heteroaryl-containing alkyl group preferably has 1 to 10 carbon atoms, and more preferably 2 to 6 carbon atoms. Examples of the heteroaryl-containing alkyl group include a pyrimidylaminoethyl group, a pyrimidylamino-2,2-dimethylpropyl group, and the like.

  The heteroaryl-containing alkenyl group is an alkenyl group containing a heteroaryl group, and the heteroaryl group and the alkenyl group may be directly bonded, or the heteroaryl group and the alkenyl group may be another divalent group ( For example, -NH- etc. may be couple | bonded. The alkenyl group of the heteroaryl-containing alkenyl group preferably has 2 to 10 carbon atoms, and more preferably 2 to 6 carbon atoms. Examples of the heteroaryl-containing alkenyl group include a pyrimidylethylenyl group.

The aryl group contained in the aryl-containing group and the heteroaryl group contained in the heteroaryl-containing group may further have a substituent. Examples of substituents include
An alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, trifluoromethyl group, etc.);
A cycloalkyl group (for example, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, etc.);
An aryl group (eg, a phenyl group, a naphthyl group, etc.);
An acylamino group (for example, an acetylamino group, a benzoylamino group, etc.);
An alkylthio group (eg, methylthio group, ethylthio group, etc.);
An arylthio group (eg, phenylthio group, naphthylthio group, etc.);
An alkenyl group (for example, vinyl group, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group, cyclohexenyl group, Styryl group);
A halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.);
An alkynyl group (eg, propargyl group);
An alkylsulfonyl group (for example, a methylsulfonyl group, an ethylsulfonyl group, etc.);
An arylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, etc.);
An alkylsulfinyl group (for example, a methylsulfinyl group);
An arylsulfinyl group (eg, a phenylsulfinyl group);
A phosphono group;
An acyl group (for example, acetyl group, pivaloyl group, benzoyl group, etc.);
A carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, butylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, morpholinocarbonyl group, etc.);
Sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthyl) Aminosulfonyl group, 2-pyridylaminosulfonyl group, etc.);
Sulfonamide groups (for example, methanesulfonamide groups, benzenesulfonamide groups, etc.);
A cyano group;
An alkoxy group (for example, methoxy group, ethoxy group, propoxy group, etc.);
An aryloxy group (eg, phenoxy group, naphthyloxy group, etc.);
A siloxy group;
An acyloxy group (for example, an acetyloxy group, a benzoyloxy group, etc.);
Sulfonic acid group; salt of sulfonic acid; aminocarbonyloxy group;
An amino group (eg, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group);
Anilino group (for example, phenylamino group, chlorophenylamino group, toluidino group, anisidino group, naphthylamino group, 2-pyridylamino group, etc.);
An imide group;
Ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.);
An alkoxycarbonylamino group (for example, a methoxycarbonylamino group, a phenoxycarbonylamino group, etc.);
Alkyloxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl, etc.);
An aryloxycarbonyl group (for example, a phenoxycarbonyl group, etc.);
Carbamate groups (eg methyl carbamate groups, phenyl carbamate groups);
Thioureido group; carboxyl group; carboxylic acid salt; hydroxyl group; mercapto group; Of these, an alkyl group, an alkoxy group, an acyloxy group, a carbamoyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, and the like are preferable, and an alkyl group, an alkoxy group, a carbamoyl group, and the like are more preferable. From the viewpoint of increasing the compatibility with the cellulose ester, polar groups such as alkoxy groups and carbamoyl groups are preferred.

L _{12 in the} general formula (1) represents a single bond, —NR ₂ —, —O—, —S—, —C (═O) —, —NR ₄ C (═O) — or —SO ₂ —. Preferably represents —NR ₂ —, —O—, —S—, —C (═O) — or —NR ₄ C (═O) —; more preferably —NR ₂ — or —NR ₄ C (= O) - are shown; more preferably -NR ₂ - shows a. -NR ₂ - _{R 2,} and _-NR 4 C (= O) in - _{R 4} in the, -NR ₁ described above - which is the same meaning as that of _{R 1} in.

A _{12 in the} general formula (1) represents an aryl-containing group, a heteroaryl-containing group or a cycloalkyl group; preferably an aryl-containing group or a heteroaryl-containing group. The aryl-containing group and the heteroaryl-containing group are respectively synonymous with the aryl-containing group and the heteroaryl-containing group represented by A ₁₁ described above. The cycloalkyl group preferably has 3 to 7 ring carbon atoms, more preferably 6 carbon atoms. The cycloalkyl group may further have a substituent similar to the substituent of the aryl group or heteroaryl group described above. Examples of the cycloalkyl group include a cyclopropyl group, a cyclohexyl group, and the like.

L _{13 in the} general formula (1) represents a single bond, —NR ₃ —, —O—, —S—, —C (═O) —, —NR ₅ C (═O) — or —SO ₂ —. Preferably —NR ₃ —, —O—, —S—, —C (═O) — or —NR ₅ C (═O) —; more preferably —NR ₃ — or —NR ₅ C (= O) —; particularly preferably —NR ₃ —. -NR ₃ - in _{R 3} and _{-NR 5 C (= O) -} R 5 in the, -NR ₁ described above - which is the same meaning as that of _{R 1} in.

A _{13 in the} general formula (1) represents an aryl-containing group, a heteroaryl-containing group, a cycloalkyl group or a hydrogen atom; preferably an aryl-containing group, a heteroaryl-containing group or a cycloalkyl group; more preferably an aryl-containing group Represents a group or a heteroaryl-containing group. The aryl-containing group and the heteroaryl-containing group have the same meanings as the above-mentioned A ₁₁ aryl-containing group and the heteroaryl-containing group, respectively, and the cycloalkyl group has the same meaning as the above-described A ₁₂ cycloalkyl group.

R _{12 in the} general formula (1) is a hydrogen atom or a divalent organic group. The divalent organic group has the same meaning as the substituent of the aryl-containing group or heteroaryl-containing group represented by A ₁₁ described above, preferably a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an aryl group, An acylamino group, a carbamoyl group, or an alkyloxycarbonyl group, more preferably a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an aryl group, or an acylamino group, still more preferably a hydrogen atom or an alkyl having 1 to 6 carbon atoms. It is a group. The acyl group constituting the acylamino group preferably has 2 to 10 carbon atoms.

Specific examples of the compound represented by the general formula (1) are shown below. First, examples of compounds having substituents at the 2-position and 4-position of the pyrimidine ring are shown. An example in which L ₁₁ is —NH— and A ₁₁ is an aryl group is shown below.

An example in which L ₁₁ is —NH—, A ₁₁ is an aryl group, and R ₁₂ is not a hydrogen atom is shown below.

An example in which L ₁₁ is —NH— and A ₁₁ is an aryl-containing alkyl group or an aryl-containing alkenyl group is shown.

An example in which L ₁₁ is —NH— and A ₁₁ is a heteroaryl group is shown.

An example in which L ₁₁ is —NH— and A ₁₁ is a heteroaryl-containing alkyl group is shown.

An example in which L ₁₁ is —NR ₁ — (R ₁ is an alkyl group or an aryl group) and A ₁₁ is an aryl group is shown.

An example in which L ₁₁ is a single bond and A ₁₁ is an aryl group is shown.

Next, examples of compounds in which the carbon atoms at the 2-position, 4-position, and 6-position of the pyrimidine ring have an aryl-containing group or a heteroaryl-containing group are shown. An example in which L ₁₁ is —NH— and A ₁₁ is an aryl group is shown.

An example in which L ₁₁ is —NH— and A ₁₁ is an aryl-containing alkyl group is shown.

An example in which L ₁₁ is —NH— and A ₁₁ is a heteroaryl group is shown.

An example in which L ₁₁ is —NH— and A ₁₁ is a heteroaryl-containing alkyl group is shown.

An example in which L ₁₁ is —NR ₁ — (R ₁ is an alkyl group) and A ₁₁ is an aryl group is shown.

An example in which L ₁₁ is a single bond and A ₁₁ is an aryl group is shown.

  The retardation developer is preferably a compound having a large birefringence in order to obtain high retardation expression. The compound having a large birefringence is preferably a compound having a high molecular polarizability and a high polarizability anisotropy. The polarizability of the compound can be determined by calculation using a molecular orbital method or a density functional method. The polarizability anisotropy of the compound can be determined by, for example, the method described in JP-A-2009-222994.

  The reason why the cellulose ester film containing the compound represented by the general formula (1) exhibits the effects of the present invention is not necessarily clear, but is estimated as follows.

That is, the compound represented by the general formula (1) includes a 2-position carbon atoms of the pyrimidine ring, an aryl-containing group or a heteroaryl-containing group (A ₁₁₎ and linking group which links (L ₁₁₎ is "single bond Or an amino group (—NH—) ”, the linking group (L ₁₁ ) linking the carbon atom at the 2-position of the pyrimidine ring and the aryl-containing group or heteroaryl-containing group (A ₁₁ ) is converted to an“ amide group ( It has a structure with higher planarity than a compound that is —NHC (═O) —) ”. Since a compound having a structure with high planarity is likely to exhibit high retardation due to polarizability anisotropy, the cellulose ester film containing the compound represented by the general formula (1) is considered to have high retardation. . Moreover, the cellulose-ester film containing the compound represented by General formula (1) is excellent also in bleed-out resistance, light resistance, wet heat resistance, etc.

  A compound having an aryl-containing group or a heteroaryl-containing group at the 2-position, 4-position and 6-position of the pyrimidine ring is higher than a compound having an aryl-containing group or a heteroaryl-containing group at the 2-position, 4-position of the pyrimidine ring. Since it has polarizability anisotropy, it is considered that a film containing it has high retardation development properties and high film brittleness (slitting characteristics).

Furthermore, in the general formula (1), a compound in which the aryl group contained in the aryl-containing group or heteroaryl-containing group represented by A _{11 to} A ₁₃ further has a substituent, or a compound further having a substituent at the 5-position of the pyrimidine ring Has a higher polarizability anisotropy than a compound not having these substituents. Therefore, these compounds are considered to have high retardation expression.

  Furthermore, in the compound represented by the general formula (1), when the number of substituents of the pyrimidine ring is large, the compatibility with the cellulose ester tends to be lowered. Therefore, compatibility with the cellulose ester can be maintained by making the terminal of at least one substituent the pyrimidine ring has as a “polar group”.

  The content of the compound represented by the general formula (1) can be adjusted by appropriately adjusting the content in order to provide a desired retardation. Specifically, the content of the compound represented by the general formula (1) is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass with respect to the cellulose ester, More preferably, it is 2-5 mass%. When the content of the compound represented by the general formula (1) is within this range, sufficient retardation can be imparted to the cellulose ester, and the bleed-out characteristics can be improved.

  The optical film of the present invention may further contain an optional component in addition to the cellulose ester and the compound represented by the general formula (1). Examples of optional components include resins other than cellulose esters, retardation developing agents other than the compounds represented by formula (1), sugar ester compounds, plasticizers, wavelength dispersion control agents, ultraviolet absorbers, and antioxidants. , And fine particles.

  Examples of resins that can be used in combination with cellulose esters include polycarbonate resins, polystyrene resins, polysulfone resins, polyester resins, polyarylate resins, acrylic resins, olefin resins (norbornene resins, cyclic olefin resins, Cyclic conjugated diene resin, vinyl alicyclic hydrocarbon resin, etc.), among others, at least one of polycarbonate resin, acrylic resin, and cyclic olefin resin. It is preferable that content of resin other than a cellulose ester is 5-70 mass% with respect to a cellulose ester.

Sugar ester compound A sugar ester compound has, for example, at least one of a pyranose structure and a furanose structure, and is obtained by esterifying all or part of OH groups contained in the structure with a monocarboxylic acid. The ester compound which can be mentioned.

Examples of the compound having a pyranose structure or furanose structure constituting the sugar ester compound include glucose, galactose, mannose, fructose, xylose, or arabinose;
Lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose; Or galactosyl sucrose.

  Especially, the compound which has both a pyranose structure and a furanose structure is preferable, Specifically, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, etc. are preferable, and sucrose is more preferable.

  The compound having a pyranose structure or furanose structure constituting the sugar ester compound is preferably an oligosaccharide. Oligosaccharides are produced by causing an enzyme such as amylase to act on starch, sucrose, etc., and specific examples include maltooligosaccharides, isomaltoligosaccharides, fructooligosaccharides, galactooligosaccharides, xylooligosaccharides, etc. .

  The monocarboxylic acid used for the esterification reaction of all or part of the OH groups contained in the pyranose structure or furanose structure is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic A group monocarboxylic acid or the like can be used. The monocarboxylic acid used may be one kind or a mixture of two or more kinds.

  Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid Saturated fatty acids such as acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid Unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, octenoic acid and the like are included.

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like.

  Preferable examples of the aromatic monocarboxylic acid include aromatic monocarboxylic acid having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalene. Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralincarboxylic acid, or derivatives thereof. More specifically, xylic acid, hemelic acid, mesitylene acid, prenicylic acid, γ-isoduric acid, duryl acid, mesitonic acid, α-isoduryl acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic Acid, salicylic acid, o-anisic acid, m-anisic acid, p-anisic acid, creosote acid, o-homosalicylic acid, m-homosalicylic acid, p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid , Isovanillic acid, veratrumic acid, o-veratormic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratorumic acid, o-homoveratric acid, phthalonic acid, p-coumaric acid, etc., especially benzoic acid Is preferred.

  Examples of the sugar ester compound include, but are not limited to, Monopet SB manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and Monopet SOA manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  The content of the sugar ester compound is preferably 0.5 to 30% by mass and more preferably 5 to 20% by mass with respect to the cellulose ester.

Plasticizer Examples of plasticizers include polyester plasticizers, polyhydric alcohol ester plasticizers, polycarboxylic acid ester plasticizers (including phthalate ester plasticizers), glycolate plasticizers, ester plasticizers. Agents (including fatty acid ester plasticizers) and acrylic plasticizers are preferred. These may be used alone or in combination of two or more.

Polyester Plasticizer The polyester plasticizer is preferably a compound represented by the following general formula (2).
General formula (2)
B- (GA) n-GB

  In formula (2), A represents a divalent group derived from an alkylene dicarboxylic acid having 4 to 12 carbon atoms or a divalent group derived from an aryl dicarboxylic acid having 6 to 12 carbon atoms. G is a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, a divalent group derived from an aryl glycol having 6 to 12 carbon atoms, or an oxyalkylene having 4 to 12 carbon atoms. Represents a divalent group derived from glycol. B represents a monovalent group derived from a hydrogen atom or a monocarboxylic acid. n represents an integer of 1 or more.

  Examples of the divalent group of A derived from an alkylene dicarboxylic acid having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid And divalent groups derived from the above. Examples of divalent groups derived from aryl dicarboxylic acids having 6 to 12 carbon atoms in A include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, etc. A divalent group derived from is included.

  Examples of the divalent group of G derived from an alkylene glycol having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 1,2-propanediol, 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-didiol) Methylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2- Methyl-1,8-octanediol, 1, - nonanediol, include divalent groups derived from 1,10-decanediol, and 1,12-octadecanediol like.

  Examples of the divalent group of G derived from an aryl glycol having 6 to 12 carbon atoms include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), and 1,4-dihydroxy. Divalent groups derived from benzene (hydroquinone) and the like are included. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Divalent groups are included.

  G is preferably a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms. This is to increase the compatibility of the polyester plasticizer with the cellulose ester.

  Examples of the monovalent group of B derived from monocarboxylic acid include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. Monovalent groups derived from, for example, aromatic monocarboxylic acids such as aminobenzoic acid, and acetoxybenzoic acid; aliphatic monocarboxylic acids such as acetic acid, propionic acid, and butyric acid.

  The number average molecular weight of the polyester plasticizer is preferably 300 to 1500, and more preferably 400 to 1000. A polyester plasticizer having a number average molecular weight of less than 300 may be easily eluted from the optical film.

  The acid value of the polyester plasticizer is preferably 0.5 mgKOH / g or less from the viewpoint of improving the adhesion between the optical film containing the polyester plasticizer and another functional layer such as a hard coat layer. The acid value of the polyester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value of the polyester plasticizer can be measured according to JIS K0070.

  The hydroxyl value of the polyester plasticizer is preferably 25 mgKOH / g or less from the viewpoint of enhancing the compatibility with the cellulose ester. The hydroxyl value of the polyester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize unreacted acetic acid when 1 g of a sample is reacted with acetic anhydride and acetylated. The hydroxyl value of the polyester plasticizer can be measured according to JIS K 0070 (1992).

Specific examples of the polyester plasticizer represented by the formula (2) are shown below.

Polyhydric alcohol ester plasticizer The polyhydric alcohol ester plasticizer is an ester compound (alcohol ester) of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a 2-20 valent aliphatic. It is a polyhydric alcohol ester. The polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  Preferred examples of the aliphatic polyhydric alcohol include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol , Galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol and the like are preferable.

  The monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, an aromatic monocarboxylic acid, or the like. In order to increase the moisture permeability of the film and make it less likely to volatilize, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred. One type of monocarboxylic acid may be sufficient and a 2 or more types of mixture may be sufficient as it. Further, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  The aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is more preferably 1-20, and still more preferably 1-10. Examples of such aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Especially, in order to improve compatibility with a cellulose ester, the mixture of an acetic acid or an acetic acid and another monocarboxylic acid is preferable.

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like.

  Examples of aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as an alkyl group, a methoxy group or an ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid or toluic acid; biphenylcarboxylic acid, naphthalene Aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acid and tetralincarboxylic acid are included, and benzoic acid is preferable.

  The molecular weight of the polyhydric alcohol ester plasticizer is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. In order to make it difficult to volatilize, a higher molecular weight is preferable; in order to improve moisture permeability and compatibility with cellulose ester, a lower molecular weight is preferable.

Polyvalent carboxylic ester plasticizer The polyvalent carboxylic ester plasticizer is an ester compound of a divalent or higher, preferably 2-20 valent polycarboxylic acid and an alcohol compound. The polyvalent carboxylic acid is preferably a 2-20 valent aliphatic polyvalent carboxylic acid, or a 3-20 valent aromatic polyvalent carboxylic acid or a 3-20 valent alicyclic polyvalent carboxylic acid. .

  Preferred examples of the polyvalent carboxylic acid include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid; succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid Aliphatic polycarboxylic acids such as maleic acid and tetrahydrophthalic acid; oxypolyvalent carboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid are included. Carboxylic acid.

  Examples of alcohol compounds include known alcohol compounds and phenol compounds. Examples of the alcohol compound include linear or branched aliphatic saturated alcohols or aliphatic unsaturated alcohols having 1 to 32 carbon atoms, more preferably 1 to 20 carbon atoms, and still more preferably 1 to 10 carbon atoms; Examples include alicyclic alcohol compounds such as pentanol and cyclohexanol; aromatic alcohol compounds such as benzyl alcohol and cinnamyl alcohol. The alcohol compound may be one kind or a mixture of two or more kinds.

  In the oxypolycarboxylic acid as the polyvalent carboxylic acid, an alcoholic or phenolic hydroxyl group may be esterified with a monocarboxylic acid. The monocarboxylic acid used for esterification can be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, or an aromatic monocarboxylic acid.

  The aliphatic monocarboxylic acid includes a linear or branched fatty acid having 1 to 32 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Examples of such aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid. Saturated fatty acids such as acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid An unsaturated fatty acid such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and the like;

  Examples of the alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid and the like. Examples of aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid Aromatic monocarboxylic acids and the like are included. Of these, acetic acid, propionic acid, and benzoic acid are particularly preferable.

  The molecular weight of the polycarboxylic acid ester plasticizer is not particularly limited, but is preferably 300 to 1000, and more preferably 350 to 750. The molecular weight of the polyvalent carboxylic acid ester plasticizer is preferably larger from the viewpoint of suppressing bleed-out; it is preferably smaller from the viewpoint of moisture permeability and compatibility with the cellulose ester.

  The acid value of the polyvalent carboxylic acid ester plasticizer is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. It is preferable to set the acid value within the above range because retardation fluctuations in the retardation are also suppressed.

  The acid value of the polyvalent carboxylic ester plasticizer is defined as the number of milligrams of potassium hydroxide required to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value can be measured according to JIS K0070.

  Examples of polycarboxylic acid ester plasticizers include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl triphenyl citrate. Benzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like are included.

  The polyvalent carboxylic acid ester plasticizer may be a phthalic acid ester plasticizer. Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

  Examples of glycolate plasticizers include alkylphthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Glycolate, and the like are included.

  The ester plasticizer includes a fatty acid ester plasticizer, a citrate ester plasticizer, a phosphate ester plasticizer, and the like.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of the citrate plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

Acrylic plasticizer Acrylic plasticizer includes at least an ethylenically unsaturated monomer Xa that does not have both an aromatic ring and a hydroxyl group in the molecule, and an ethylenically unsaturated monomer Xb that does not have an aromatic ring in the molecule and has a hydroxyl group. And a polymer Y having an ethylenically unsaturated monomer Ya having no aromatic ring in the molecule as a polymerization component. The ethylenically unsaturated monomer is preferably a (meth) acrylic acid ester.

The polymer X preferably has a structure represented by the following general formula (X). The following formula _{(X) - [CH 2 -C} (-Rc) (- CO 2 Rd)] m- is a group derived from an ethylenically unsaturated monomer _{Xa; - [CH 2 -C (} -Re ) (— CO ₂ Rf—OH) —] n— is a group derived from the ethylenically unsaturated monomer Xb.
Formula (X)
_{- [CH 2 -C (-Rc)} (- CO 2 Rd)] m- [CH 2 -C (-Re) (- CO 2 Rf-OH) -] n- [Xc] p-

  Rc and Re in the formula (X) represent a hydrogen atom or a methyl group. Rd represents an alkylene group having 1 to 12 carbon atoms or a cycloalkylene group. Rf represents a methylene group, an ethylene group or a propylene group. Xc represents a monomer unit polymerizable to Xa and Xb. m, n and p represent molar composition ratios. However, m and n are not 0, and m + n + p = 100. The weight average molecular weight of the polymer X is preferably 3000 to 30000.

The polymer Y preferably has a structure represented by the following general formula (Y). The following formula _{(Y) - [CH 2 -C} (-Rg) (- CO 2 Rh-OH) -] k- is a group derived from an ethylenically unsaturated monomer Ya.
General formula (Y)
_{Ry- [CH 2 -C (-Rg)} (- CO 2 Rh-OH) -] k- [Yb] q-

  Rg in the formula (Y) represents a hydrogen atom or a methyl group. Rh represents a methylene group, an ethylene group or a propylene group. Ry represents a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 3 carbon atoms. Yb represents a monomer unit copolymerizable with Ya. k and q represent a molar composition ratio. However, k is not 0 and k + q = 100. The weight average molecular weight of the polymer Y is preferably 500 or more and 3000 or less.

  The total content of these plasticizers is preferably 0.5 to 30% by mass and more preferably 5 to 20% by mass with respect to the cellulose ester.

Wavelength Dispersion Control Agent The optical film of the present invention may further contain a wavelength dispersion control agent. The wavelength dispersion controlling agent has a function of adjusting the wavelength dispersion characteristic of the retardation of the film.

  The wavelength dispersion controlling agent is preferably a compound having an absorption maximum in a wavelength range of 250 nm to 400 nm, and more preferably a compound having an absorption maximum in a wavelength range of 270 nm to 380 nm in the light absorption spectrum. Preferable examples of the wavelength dispersion control agent include discotic compounds described in JP-A Nos. 2001-166144 and 2003-3446556; compounds described in JP-A 2010-163482, and the like.

  The content of the wavelength dispersion controlling agent is preferably 0.5 to 20% by mass and more preferably 1 to 10% by mass with respect to the entire resin component contained in the optical film.

Ultraviolet Absorber The optical film of the present invention may further contain an ultraviolet absorber in order to improve the durability of the optical film. The ultraviolet absorber is a compound that absorbs ultraviolet rays having a wavelength of 400 nm or less, preferably a compound having a transmittance at a wavelength of 370 nm of 10% or less, more preferably 5% or less, and even more preferably 2% or less. Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, etc. Is a benzotriazole ultraviolet absorber, a benzophenone ultraviolet absorber, or a triazine ultraviolet absorber, more preferably a benzotriazole ultraviolet absorber or a benzophenone ultraviolet absorber.

  Specific examples of the ultraviolet absorber include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl)- In addition to 6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., commercially available products Tinobine 109 and Tinuvin manufactured by BASF Japan 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928 and the like are included. These ultraviolet absorbers may be only one kind or a mixture of two or more kinds.

  In addition to these, polymer ultraviolet absorbers and discotic compounds are also preferably used as ultraviolet absorbers. As the polymer ultraviolet absorber, a polymer type ultraviolet absorber described in JP-A-6-148430 is particularly preferably used, and as the discotic compound, for example, a compound having a 1,3,5-triazine ring is preferably used.

  Although content of a ultraviolet absorber is based also on the kind of ultraviolet absorber, etc., it is preferable that it is 0.5-10 mass% with respect to the whole optical film, and it is more preferable that it is 0.6-4 mass%. preferable.

Antioxidant The optical film of the present invention may further contain an antioxidant, for example, in order to prevent deterioration of the optical film that is likely to occur under high humidity and high temperature. The antioxidant has a function of delaying or preventing the decomposition of the residual solvent amount in the optical film by halogen or phosphoric acid based plasticizer.

  The antioxidant is preferably a hindered phenol compound, and specific examples thereof include 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-oxide). -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl- -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1, 3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl)- Isocyanurate and the like are included. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.

  These compounds include, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, tris (2,4 It may be used in combination with a phosphorus processing stabilizer such as -di-t-butylphenyl) phosphite.

  The content of the antioxidant is preferably 1 ppm to 1.0% by mass ratio with respect to the cellulose ester, and more preferably 10 to 1000 ppm.

Fine particles The optical film of the present invention may further contain fine particles in order to improve slipperiness. The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate And calcium phosphate. Examples of organic fine particles include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, melamine Resin, polyolefin powder, polyester resin, polyamide resin, polyimide resin, polyfluorinated ethylene resin, pulverized classification of organic polymer compounds such as starch, polymer compound synthesized by suspension polymerization method, spray High molecular compounds made spherical by a dry method or a dispersion method are included. In order to reduce the increase in the haze of the film, fine particles containing silicon are preferable, and silicon dioxide is particularly preferable.

  Examples of the silicon dioxide fine particles include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (commercially available from Nippon Aerosil Co., Ltd.). Of these, Aerosil 200V and Aerosil R972V are preferred because of the great effect of reducing the coefficient of friction while keeping the haze of the optical film low.

  The primary average particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. The content of the fine particles is preferably adjusted so that the dynamic friction coefficient of at least one surface of the optical film is 0.2 to 1.0. Specifically, the content of the fine particles is preferably 0.01 to 1% by mass and more preferably 0.05 to 0.5% by mass with respect to the optical film.

  Although the thickness of an optical film is not specifically limited, It is preferable that it is 10-200 micrometers, It is more preferable that it is 10-100 micrometers, It is further more preferable that it is 20-60 micrometers. If the thickness of the optical film is too large, the variation in retardation tends to increase due to humidity. On the other hand, if the thickness of the film is too small, it is difficult to obtain a desired retardation. When the film thickness is in the above range, humidity dependency is small, and high retardation is easily obtained by the compound represented by the general formula (1). Further, if the film thickness is in the above range, the film is highly brittle, and the slitting characteristics are also good.

  The optical film of the present invention is preferably used as an optical compensation film. That is, since the liquid crystal display has an anisotropic liquid crystal material and a polarizing plate, the display screen may be displayed well when viewed from the front, but may not be displayed well when viewed from an oblique direction. (There is viewing angle dependency). The optical compensation film is effective in reducing such viewing angle dependency.

  The refractive index distribution of the liquid crystal cell is usually large in the thickness direction of the liquid crystal cell and small in the in-plane direction. Therefore, it is preferable that the optical compensation film cancels the anisotropy of the refractive index; that is, the refractive index distribution has a negative uniaxiality that is small in the thickness direction and large in the in-plane direction. The optical film of the present invention is preferably used as a film having such an optical compensation function.

In the optical film of the present invention, the retardation Ro measured at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH is preferably 20 to 150 nm, and more preferably 70 to 145 nm. The retardation Rth measured at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH is preferably 70 to 300 nm, and more preferably 170 to 270 nm. The retardations _R0 and Rth of the optical film can usually be adjusted by stretching conditions.

The in-plane direction retardation R ₀ and the thickness direction retardation Rth are each expressed by the following equations.
Formula (I) R ₀ = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction in the film plane, ny: refractive index in the direction perpendicular to the slow axis in the film plane, nz: refractive index of the film in the thickness direction, d: film thickness (Nm))

The retardations _R0 and Rth can be determined by the following method, for example.
1) The average refractive index of the film is measured with a refractometer.
2) The retardation _R0 in the in-plane direction when light having a wavelength of 590 nm from the normal direction of the film is incident is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments.
3) The retardation value R (θ) when light having a wavelength of 590 nm is incident from the angle θ (incident angle (θ)) with respect to the film normal direction is measured by KOBRA-21ADH manufactured by Oji Scientific Instruments. . θ is larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R ₀ and R (θ) and the above-described average refractive index and film thickness, nx, ny and nz are calculated by KOBRA-21ADH manufactured by Oji Scientific Instruments, and Rth is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

  The optical film of the present invention has a slow axis or a fast axis in the film plane. The angle θ1 (orientation angle) between the slow axis and the film forming direction is preferably from −1 ° to + 1 °, and more preferably from −0.5 ° to + 0.5 °. Since the light leakage can be suppressed when the orientation angle θ1 satisfies the above range, the luminance of the display image can be increased.

The retardation _R0 and Rth of the optical film and the orientation angle θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

The moisture permeability of the optical film at 40 ° C. and 90% RH measured in accordance with JIS Z 0208 is preferably 10 to 1200 g / m ² · 24 h. In order to reduce the moisture permeability of the optical film, for example, the total acyl group substitution degree of the cellulose ester contained in the optical film is increased, the ratio of the acyl group substitution degree of 3 or more carbon atoms is increased, a plasticizer, etc. A large amount of the additive may be contained.

  The visible light transmittance of the optical film of the present invention is preferably 90% or more, and more preferably 93% or more. The haze of the optical film of the present invention is preferably less than 1%, particularly preferably 0.1% or less. The breaking elongation of the optical film of the present invention is preferably 10 to 80%.

2. Manufacturing method of optical film Cellulose ester film can be manufactured by solution casting method or melt casting method, and from the viewpoint of obtaining a thin film with high flatness, it should be manufactured by solution casting method. Is preferred.

  The step of producing a cellulose ester film by the solution casting method is 1) a step of preparing a dope by dissolving at least the above-mentioned cellulose ester and, if necessary, an additive in a solvent, and 2) an endless metal support for the dope. A step of casting on a body, 3) a step of drying the cast dope to form a web, 4) a step of peeling the web from the metal support, 5) a step of stretching the web to obtain a film, and 6) a film And 7) a step of winding up the obtained film.

1) Process for preparing dope The dope is prepared by dissolving the above cellulose ester and, if necessary, an additive in a solvent. The concentration of the cellulose ester contained in the dope is preferably high in order to reduce the drying load. However, if the concentration of the cellulose ester is too high, it is difficult to filter, and the filtration accuracy tends to decrease. For this reason, it is preferable that the density | concentration of the cellulose ester contained in dope is 10-35 mass%, and it is more preferable that it is 15-25 mass%.

  The solvent contained in the dope may be one kind or a combination of two or more kinds. From the viewpoint of increasing production efficiency, it is preferable to use a combination of a good solvent and a poor solvent for cellulose ester. A good solvent refers to a solvent that dissolves cellulose ester alone, and a poor solvent refers to a solvent that swells cellulose or does not dissolve alone. Therefore, the good solvent and the poor solvent differ depending on the average acyl group substitution degree (acetyl group substitution degree) of the cellulose ester.

  When a good solvent and a poor solvent are used in combination, it is preferable that the good solvent is more than the poor solvent in order to increase the solubility of the cellulose ester. The mixing ratio of the good solvent and the poor solvent is preferably 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.

  Examples of the good solvent include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate, and preferably methylene chloride or methyl acetate. Examples of the poor solvent include methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like. The dope preferably contains 0.01 to 2% by mass of water.

  The method of dissolving the cellulose ester in the solvent may be a general method, for example, a method of dissolving under heating and pressure, a poor solvent added to the cellulose ester to swell, and then adding a good solvent to dissolve. It can be a method. Especially, since it can heat beyond the boiling point in a normal pressure, the method of making it melt | dissolve under a heating and pressurization is preferable. Specifically, when stirring and dissolving while heating to a temperature in the range where the solvent is boiling or higher under normal pressure and the solvent does not boil under pressure, the generation of bulk undissolved material called gel or mamako can be suppressed.

  The pressurization can be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature is preferably higher from the viewpoint of increasing the solubility of the cellulose ester, but if it is too high, the pressure needs to be increased, and the productivity is lowered. For this reason, it is preferable that heating temperature is 45-120 degreeC, 60-110 degreeC is more preferable, and it is further more preferable that it is 70-105 degreeC. The pressure is adjusted to a range in which the solvent does not boil at the set heating temperature.

  Additives such as UV inhibitors and fine particles may be added batchwise to the dope, or an additive solution prepared separately may be added inline. The additive solution is obtained by dissolving an additive in an alcohol such as methanol, ethanol or butanol, a solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof.

  In particular, part or all of the fine particles are preferably added in-line in order to reduce the load on the filter medium. When the additive solution is added in-line, it is preferable to dissolve a small amount of cellulose ester in the additive solution in order to improve mixing with the dope. The amount of the cellulose ester added to the additive solution is preferably 1 to 10 parts by mass and more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  The in-line addition can be performed using an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer), or the like.

  The obtained dope may contain insoluble matters such as impurities contained in the cellulose ester as a raw material, for example. Such an insoluble matter can become a bright spot foreign material in the obtained film. In order to remove such insoluble matter and the like, it is preferable to filter the obtained dope.

  The dope is filtered by a filter medium such as filter paper. The absolute filtration accuracy of the filter medium is preferably small in order to highly remove insoluble matters and the like contained in the dope, but if it is too small, clogging is likely to occur. For this reason, the absolute filtration accuracy of the filter medium is preferably 0.008 mm or less, more preferably 0.001 to 0.008 mm, and still more preferably 0.003 to 0.006 mm.

  The type of the filter medium may be a normal filter medium, and may be a plastic filter medium such as polypropylene or Teflon (registered trademark), or a metal filter medium such as stainless steel. Among these, a metal filter medium is preferable from the viewpoint of less fiber dropping.

  In order to reduce the differential pressure before and after filtration, the dope is preferably filtered under heating and pressure as in the preparation of the dope. Similarly to the preparation of the dope, the heating temperature is preferably not less than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure, specifically 45 to 120 ° C. It is preferably 45 to 70 ° C, more preferably 45 to 55 ° C. The filtration pressure is preferably low, specifically 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

The dope filtration is preferably performed so that the number of bright spot foreign matters in the obtained film is not more than a certain value. Specifically, the number of bright spot foreign matters having a diameter of 0.01 mm or more is 200 / cm ² or less, preferably 100 / cm ² or less, more preferably 50 / m ² or less, and still more preferably 0. -10 pieces / cm ² or less. It is preferable that the number of bright spot foreign materials having a diameter of 0.01 mm or less is also small.

The number of bright spot foreign matter on the film can be measured by the following procedure.
i) Two polarizing plates are arranged in a crossed Nicol state, and the obtained film is arranged between them.
ii) Count the number of spots (foreign matter) where light is leaked when light is applied from one polarizing plate and observed from the other polarizing plate.

2) Step of casting dope The metal support on which the dope is cast preferably has a mirror-finished surface. Preferred examples of the metal support include a stainless steel belt and a drum whose surface is plated with a casting.

  The surface temperature of the metal support on which the dope is cast is preferably high in order to increase the drying speed of the web, but if it is too high, the web may foam or the smoothness of the web may be reduced. . Therefore, the surface temperature of the metal support is preferably set to −50 ° C. or higher and lower than the boiling point of the solvent, more preferably 0 to 40 ° C., and further preferably 5 to 30 ° C.

  The method for controlling the surface temperature of the metal support is not particularly limited, and may be a method of blowing warm air or cold air, a method of bringing hot water into contact with the back side of the metal support, or the like. From the viewpoint of efficiently transferring heat and shortening the time until the temperature of the metal support becomes constant, a method of bringing hot water into contact with the back side of the metal support is preferable.

3) About the process of drying the cast dope The cast dope is dried so that a residual solvent may become below fixed. The amount of residual solvent in the web when peeling the web from the metal support is preferably 10 to 150% by mass in order to improve the flatness of the resulting film, and 20 to 40% by mass (low residual solvent amount). Or it is more preferable that it is 60-130 mass% (high residual solvent amount), and it is further more preferable that it is 20-30 mass% (low residual solvent amount) or 70-120 mass% (high residual solvent amount).

The amount of residual solvent in the web is defined by the following formula. In the following formula, M represents the mass of a sample collected at an arbitrary point from the web being manufactured or the film after manufacture. N represents the mass of the sample after heating the sample at 115 ° C. for 1 hour.
Residual solvent amount (% by mass) = {(MN) / N} × 100

4) About the process of peeling a web Although peeling of a web is performed by a general method, it is preferable to peel with a peeling roll. Peeling with a peeling roll is preferably carried out when the web reaches the lower surface of the metal support and almost completes a round. The web peeling tension is preferably 300 N / m or less.

  The peeling of the web is not only the method of peeling after the web is dried in the step 3), but also after the step 2), the cast film is cooled without being dried and contains a large amount of residual solvent. After gelling as it is, it may be peeled off.

  The peeled web may be further dried. In general, the peeled web can be dried while the web is conveyed. Specifically, there are a roll drying method and a tenter method in which the peeled web is dried while being conveyed by a large number of rolls arranged vertically.

  The method for drying the web is not particularly limited, but in general, it may be a method of drying with hot air, infrared rays, heating rolls, microwaves, or the like, and from the viewpoint of simplicity, a method of drying with hot air is preferable. The drying temperature of the web is preferably increased stepwise from 40 ° C to 200 ° C.

5) About the process of extending | stretching a web The optical film which has desired retardation value Ro and Rth is obtained by extending | stretching a web. The retardation values Ro and Rth of the optical film can be controlled by adjusting the magnitude of the tension applied to the web at least in the direction (width direction) perpendicular to the web conveyance direction (the dope casting direction). it can.

  The web may be stretched at least in the width direction, and may be uniaxial stretching or biaxial stretching. The web may be stretched in the width direction or in an oblique direction with respect to the casting direction of the dope. Biaxial stretching includes stretching in both the web conveyance direction (longitudinal direction) and the width direction (lateral direction). Stretching may be sequential stretching or simultaneous stretching.

  When the web is stretched biaxially in directions orthogonal to each other, the web is finally 1.1 to 2.5 times in the width direction (lateral direction) and 0.8 in the transport direction (longitudinal direction). It is preferable to set it to -1.5 times; It is more preferable to set it to 1.2 to 2.0 times in the width direction (horizontal direction) and 0.9 to 1.0 times in the conveyance direction (vertical direction).

  The web stretching temperature is preferably 120 ° C to 200 ° C, and more preferably 140 ° C to 180 ° C. The residual solvent of the stretched web is preferably 20% by mass or less, and preferably 15% by mass or less.

  The method of stretching the web is not particularly limited, and a method in which a difference in peripheral speed is applied to a plurality of rolls and the roll is stretched in the longitudinal direction using the difference in the peripheral speed of the roll (roll stretching method). The clip and pin spacing is widened in the vertical direction and stretched in the vertical direction, widened in the horizontal direction and stretched in the horizontal direction, or stretched in both the vertical and horizontal directions and stretched in both the vertical and horizontal directions (tenter stretching, etc. Law). These stretching methods may be combined.

  In the tenter stretching method, the clip portion is preferably driven by a linear drive method. This is because the movement of the clip portion is smooth, so that it is easy to stretch and the risk of web breakage can be reduced.

  It is preferable to carry out the web width maintenance and the transverse stretching by a tenter method. The tenter method may be a pin tenter method or a clip tenter method.

  The width of the optical film obtained by stretching is preferably 4 m or less, more preferably 1 to 4 m, even more preferably 1.4 to 4 m, from the viewpoint of facilitating conveyance. It is particularly preferably 1.6 to 3 m. The optical film obtained by stretching is further dried as necessary and then wound.

  The optical film of the present invention is used as a functional film for various display devices such as liquid crystal displays, plasma displays, and organic EL displays. In particular, the optical film of the present invention includes a polarizing plate protective film, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for widening the viewing angle, etc. for liquid crystal display devices. It can be.

3. Polarizing plate The polarizing plate of the present invention includes a polarizer and the optical film of the present invention disposed on one surface thereof, and further includes a polarizing plate protective film disposed on the other surface of the polarizer as necessary. May be included.

  A polarizer is an element that allows only light having a polarization plane in a certain direction to pass therethrough. A typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.

  The polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing with iodine or a dichroic dye, or after dyeing a polyvinyl alcohol film with iodine or a dichroic dye, A uniaxially stretched film (preferably a film further subjected to durability treatment with a boron compound) may be used. The thickness of the polarizer is preferably 5 to 30 μm, and more preferably 10 to 20 μm.

  The polyvinyl alcohol film may be a film formed from a polyvinyl alcohol aqueous solution. The polyvinyl alcohol film is preferably an ethylene-modified polyvinyl alcohol film because it is excellent in polarizing performance and durability performance and has few color spots. Examples of the ethylene-modified polyvinyl alcohol film include an ethylene unit content of 1 to 4 mol%, a polymerization degree of 2000 to 4000, and a saponification degree of 99 described in JP2003-248123A, JP2003-342322A, and the like. 0.0 to 99.99 mol% film is included.

  Examples of dichroic dyes include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.

  The optical film of the present invention may be disposed directly on one surface of the polarizer or may be disposed via another film or layer. The optical film of the present invention is preferably an optical compensation film that also functions as a polarizing plate protective film. This is because it is not necessary to further use an optical compensation film separately from the polarizing plate protective film, and not only the liquid crystal display device can be thinned but also the manufacturing process can be simplified.

  The polarizing plate protective film other than the optical film of the present invention is not particularly limited, and may be a normal cellulose ester film or the like. Examples of commercially available cellulose ester films include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-X KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

  The polarizing plate can usually be produced by laminating the polarizer and the optical film or polarizing plate protective film of the present invention. As the adhesive used for bonding, for example, a completely saponified polyvinyl alcohol aqueous solution is preferably used.

4). Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one is a polarizing plate which has the above-mentioned optical film among a pair of polarizing plates, Preferably both of a pair of polarizing plates are the polarizing plates which have the above-mentioned optical film.

  FIG. 1 is a schematic diagram showing a basic configuration of an embodiment of a liquid crystal display device according to the present invention. As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal cell 20, a first polarizing plate 40 and a second polarizing plate 60 that sandwich the liquid crystal cell 20, and a backlight 80.

  The display method of the liquid crystal cell 20 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an IPS (In-Plane Switching) method, an OCB (Optically Compensated Birefringence Ventilating Ventilation method). There are systems (including MVA; Multi-domain Vertical Alignment and PVA; including Patterned Vertical Alignment), and HAN (Hybrid Aligned Nematic). In order to increase the contrast, the VA (MVA, PVA) method is preferable.

  A VA liquid crystal cell usually includes a pair of opposing transparent substrates and a liquid crystal layer that is sandwiched between the pair of transparent substrates and includes positive liquid crystal.

  Of at least one of the pair of transparent substrates, a pixel electrode for applying a voltage to the positive liquid crystal and a counter electrode corresponding to the pixel electrode are disposed.

  The liquid crystal layer includes positive liquid crystal molecules that are nematic liquid crystal materials having positive dielectric anisotropy. This positive type liquid crystal molecule is not applied with voltage (when no electric field is generated between the pixel electrode and the counter electrode) due to the alignment regulating force of the alignment film provided on the liquid crystal layer side surface of the transparent substrate. The major axis of the liquid crystal molecules is aligned so as to be substantially perpendicular to the surface of the transparent substrate.

  In the liquid crystal cell thus configured, an image signal (voltage) is applied to the pixel electrode, thereby generating an electric field in the horizontal direction with respect to the substrate surface between the pixel electrode and the counter electrode. Thereby, the liquid crystal molecules initially aligned perpendicularly to the surface of the transparent substrate are aligned so that the major axis thereof is in the horizontal direction with respect to the substrate surface. In this way, the liquid crystal layer is driven, and the image display is performed by changing the transmittance and reflectance of each sub-pixel.

  The 1st polarizing plate 40 is arrange | positioned at the visual recognition side, and has the 1st polarizer 42 and polarizing plate protective film 44 (F1) and 46 (F2) which clamps it. The 2nd polarizing plate 60 is arrange | positioned at the backlight 80 side, and has the 2nd polarizer 62, the polarizing plate protective film 64 (F3) and polarizing plate protective film 66 (F4) which clamps it. . One of the polarizing plate protective films 46 (F2) and 64 (F3) may be omitted as necessary.

  Of the polarizing plate protective films 44 (F1), 46 (F2), 64 (F3) and 66 (F4), at least one of the polarizing plate protective films 46 (F2) and 64 (F3) disposed on the liquid crystal cell side is used. The optical film of the present invention is preferred. The polarizing plate protective film 44 (F1) disposed on the display side may further include an antiglare layer, a clear hard coat layer, an antireflection layer, an antistatic layer, an antifouling layer, or a backcoat layer.

  As described above, the optical film of the present invention has a high retardation, and there is little variation in retardation depending on humidity and temperature conditions. Therefore, the liquid crystal display device of the present invention having the optical film of the present invention on the liquid crystal cell side of the polarizer has a high front contrast, and the front contrast unevenness and the viewing angle dependency which are likely to occur depending on the humidity and temperature conditions are increased. It is suppressed.

  In the following, the invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.

1. Preparation of materials 1) Cellulose ester Cellulose ester A: Cellulose diacetate (DAC) having a total acyl group substitution degree of 2.40 and an acetyl group substitution degree of 2.40
Cellulose ester B: cellulose acetate propionate (CAP) having a total acyl group substitution degree of 2.46, an acetyl group substitution degree of 1.56, and a propionyl group substitution degree of 0.9
Cellulose ester C: cellulose triacetate (TAC) having a total acyl group substitution degree of 2.87 and an acetyl group substitution degree of 2.87

2) Retardation expression agent a) Synthesis of exemplary compound PM-2 p-anisidine 5.2 g, 2,4-dichloropyrimidine 3.0 g, and sulfolane 20 ml were mixed and stirred at 150 ° C. for 3 hours. After allowing to cool to room temperature, 50 ml of methanol and 50 ml of water were sequentially added, and the precipitate was collected by filtration. The obtained precipitate was recrystallized with acetone to obtain 5.2 g of Exemplified Compound PM-2. The molecular structure of the obtained exemplary compound PM-2 was identified by NMR and mass spectrum.

b) Synthesis of Exemplified Compound PM-43 4.4 g of p-anisidine, 2.0 g of trichloropyrimidine and 10 ml of sulfolane were mixed and stirred at 180 ° C. for 3 hours. After allowing to cool to room temperature, 70 ml of ethyl acetate and 40 ml of water were sequentially added, and the precipitate was collected by filtration. The obtained precipitate was purified by column chromatography to obtain 3.2 g of Exemplified Compound PM-43. The molecular structure of the obtained exemplary compound PM-43 was identified by NMR and mass spectrum.

The following exemplary compounds were synthesized in the same manner as exemplary compound PM-2 or PM-43, respectively.

Ｂ００２は、トリアジン化合物とピリミジン化合物とを１：１のモル比で含む混合物である。 Moreover, the following compounds were prepared as comparative compounds.

B002 is a mixture containing a triazine compound and a pyrimidine compound in a molar ratio of 1: 1.

2. Production of optical film (Example 1)
The following components were stirred and mixed with a dissolver for 50 minutes and then dispersed with Manton Gorin to obtain a fine particle dispersion.
[Fine particle dispersion]
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 88 parts by mass

While the methylene chloride was put in the dissolution tank and sufficiently stirred, the fine particle dispersion was slowly added, and then dispersed with an attritor so that the secondary particles had a predetermined particle size. The obtained solution was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.
[Fine particle additive solution]
Methylene chloride 101 parts by weight Fine particle dispersion 5 parts by weight

Preparation of dope solution A dope solution having the following composition was prepared. First, methylene chloride and ethanol were charged into a pressure dissolution tank. Cellulose ester A (cellulose diacetate having a total acyl group substitution degree of 2.40 and an acetyl group substitution degree of 2.40) was added to these solvents while stirring. The obtained solution was dissolved while stirring under heating, and the exemplary compound PM-1 as a retardation developer, Monopet SB (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a sugar ester compound, and a fine particle additive solution were further added. Added and stirred until completely dissolved. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a dope solution.
[Composition of dope solution]
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose ester A (total acyl group substitution degree 2.40, acetyl group substitution degree 2.40, cellulose diacetate) 100 parts by mass Retardation developer: Exemplified compound PM-1 4 parts by mass Monopet SB (Daiichi Kogyo Seiyaku Co., Ltd.) 5.5 parts by mass Particulate additive solution 1 part by mass

  Next, the dope solution adjusted to 34 ° C. was uniformly cast on a stainless belt support of an endless belt casting apparatus so as to have a width of 1500 mm. The temperature of the stainless steel belt support was 30 ° C. After the solvent was evaporated on the stainless steel belt support until the residual solvent amount in the cast film was 75%, the paint film was applied from the stainless steel belt support at a peeling tension of 130 N / m. It peeled. The web obtained by peeling was stretched by 20% in the width direction using a tenter while applying heat at 140 ° C. The residual solvent amount of the web at the start of stretching was 15%. Next, drying was terminated while the drying zone was conveyed by a number of rolls. The film obtained by stretching was dried at a drying temperature of 130 ° C. while being transported at a transport tension of 100 N / m. Thereby, an optical film 101 having a thickness of 40 μm was obtained.

(Examples 2 to 17)
As shown in Table 1, optical films 102 to 117 were obtained in the same manner as in Example 1 except that the type of cellulose ester, the type of retardation developer, and the content thereof were changed.

(Examples 18 to 23)
As shown in Table 1, optical films 118 to 123 were obtained in the same manner as in Example 12 except that the film thickness was changed.

(Comparative Examples 1-8)
As shown in Table 2, optical films 124 to 131 were obtained in the same manner as in Example 1 except that the type of cellulose ester, the type of retardation developer, and the content thereof were changed.

  Retardation Ro and Rth, slitting characteristics, and bleed out characteristics of the obtained optical film were evaluated by the following methods.

Measurement of retardation Ro and Rth 1) The obtained film was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH to adjust the humidity. The average refractive index of the obtained film was measured using an Abbe refractometer (4T). Moreover, the thickness of the film was measured using a commercially available micrometer.
2) Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), light having a wavelength of 590 nm from the normal direction of the film is incident, and in the in-plane direction represented by the following formula (I) Retardation Ro was measured. Further, the retardation value R (θ) was measured when light having a wavelength of 590 nm was incident from an angle θ (incident angle (θ)) with respect to the film normal direction. θ was 30 ° to 50 °.
3) nx, ny and nz are calculated from the measured R ₀ and R (θ) and the above-mentioned average refractive index and film thickness by an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments). Rth represented by the following formula (II) was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the film;
ny represents the refractive index in the direction y perpendicular to the direction x in the in-plane direction of the film;
nz represents the refractive index in the film thickness direction z;
d (nm) indicates the film thickness)

Slitting characteristics (brittleness)
An upper blade whose blade edge was worn at 60 ° and a lower blade of 90 ° were attached to a hydraulic table press so that the horizontal interval was 30 μm. Then, the obtained film is set between the tip of the upper blade and the tip of the lower blade, and a sample piece having a width of 90 cm and a length of 100 cm under the condition of the lowering speed of the upper blade of 6 m / min, 100 sheets were cut out continuously. The cut surface of each sample piece cut out was observed 50 times using an optical microscope. The number of films with defects such as burrs, cleavage, inability to cut, and generation of chips was counted and applied to the following formula to calculate the defect rate.
Defect rate (%) = (number of films with defects / number of all cut out films (100 sheets)) × 100

The slitting characteristics were evaluated based on the following criteria.
A: The defect rate is less than 2% B: The defect rate is 2% or more and less than 5% C: The defect rate is 5% or more and less than 10% D: The defect rate is 10% or more

Bleed-out resistance The obtained film was allowed to stand for 1000 hours in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH. Thereafter, the presence or absence of bleed-out (crystal precipitation) on the film surface was visually observed. The bleed-out resistance was evaluated based on the following criteria. A and B were judged to be at a level where there was no practical problem.
A: No bleed-out is observed on the surface B: Partial bleed-out is slightly observed on the surface C: Slight bleed-out is observed on the entire surface D: Clear bleed-out is recognized on the entire surface Be

The evaluation results of the optical films of Examples 1 to 23 are shown in Table 1, and the evaluation results of the optical films of Comparative Examples 1 to 8 are shown in Table 2. In Tables 1 and 2, Dall represents the total acyl group substitution degree of the cellulose ester; Dac represents the acetyl group substitution degree; Dpr represents the propyl group substitution degree.

  As shown in Table 1, the optical films of Examples 1 to 23 containing a pyrimidine compound represented by the general formula (1) (a compound having an amino group at the 2-position of the pyrimidine ring) as a retardation developer are high. It turns out that it has retardation Ro and Rth, and has favorable brittleness (slitting suitability) and durability (bleed-out resistance).

  On the other hand, as shown in Table 2, it can be seen that the optical films of Comparative Examples 6 to 8 containing no retardation developer have a small retardation value and no optical compensation function. Moreover, although the optical film of the comparative examples 1 and 2 containing a triazine compound as a retardation developer has a relatively high retardation, it can be seen that brittleness (slitability) and durability (bleedout resistance) are low. Furthermore, it can be seen that the optical films of Comparative Examples 3 to 5 containing a conventional pyrimidine compound (a compound having an amide group at the 2-position of the pyrimidine ring) cannot obtain a sufficient retardation value.

Specifically, from the comparison between Example 3 and Comparative Example 3, when the group (L ₁₁ ) linked to the 2-position of the pyrimidine ring is an amino group, the retardation is higher than that of an amide group, and the bleed out It is difficult to do. Further, from the comparison between Example 10 and Comparative Example 1, it can be seen that the main skeleton having a pyrimidine ring has higher retardation than the triazine ring and is less likely to bleed out.

  Further, from the comparison between Examples 1 and 8 or the comparison between Examples 2 and 9, the compounds having aryl-containing groups at the 2-position, 4-position and 6-position of the pyrimidine ring are the 2-position and 4-position of the pyrimidine ring. It can be seen that the retardation development is higher than the compound having an aryl-containing group, and the film is more brittle.

Moreover, from the comparison between Example 8 and Examples 9 to 10 and 12, it can be seen that higher retardation is obtained when A _{11 to} A ₁₃ in Formula (1) further have a substituent.

Further, from the comparison between Example 1 and Example 7, the compound in which R ₁₂ in the formula (1) is an alkyl group has higher retardation expression than the compound in which R ₁₂ in the formula (1) is a hydrogen atom. I understand that.

  Further, as shown in Examples 1 and 18 to 23, the film thickness is in the range of 20 to 60 μm, has high retardation, and has good brittleness (slitability) and durability (bleedout resistance). It can be seen that

3. Production of Polarizing Plate and Liquid Crystal Display (Example 24)
Production of Polarizing Plate A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched under conditions of a temperature of 110 ° C. and a stretch ratio of 5 times. The obtained film was immersed in an aqueous solution consisting of 0.071 g of iodine, 5 g of potassium iodide and 100 g of water for 55 seconds, and then immersed in an aqueous solution of 65 ° C. consisting of 6 g of potassium iodide, 7.1 g of boric acid and 100 g of water. . The film after immersion was washed with water and dried to obtain a polarizer having a thickness of 25 μm.

Then, according to the following steps 1 to 5, the optical film 101 is bonded to one surface of the polarizer, and Konica Minolta Tack KC4UY (cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) is bonded to the other surface of the polarizing plate 101. Was made.
Step 1: Optical film 101 and Konica Minolta Tac KC4UY were each immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds. The obtained film was washed with water and dried to obtain a film in which the surface to be bonded to the polarizer was saponified.
Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.
Step 3: After lightly wiping off the excess adhesive adhering to the polarizer in Step 2, the optical film 101 saponified in Step 1 is laminated on one side of the polarizer, and saponifying in Step 1 on the other side. The processed Konica Minolta Tack KC4UY was laminated.
Step 4: The optical film 101 / polarizer / Konica Minoltaack KC4UY laminate obtained in Step 3 was bonded under the conditions of a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.
Step 5: The sample bonded in Step 4 was dried at 80 ° C. for 2 minutes with a dryer to obtain a polarizing plate 101.

(Examples 25-46 and Comparative Examples 9-13)
Polarizing plates 102 to 123 and 124 to 128 were obtained in the same manner as in Example 24 except that the optical film 101 was changed as shown in Table 3.

  The light resistance and wet heat resistance of the obtained polarizing plate were evaluated by the following methods.

Light Resistance The parallel transmittance (H0) and direct transmittance (H90) of the obtained polarizing plate were measured using Haze Meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The obtained value was applied to the following formula to calculate the polarization degree P0 before the forced deterioration treatment.
Polarization degree P0 = [(H0−H90) / (H0 + H90)] / 2 × 100
Next, the polarizing plate was subjected to a forced deterioration treatment with a sunshine weather meter for 500 hours under the condition without a UV cut filter. Thereafter, the parallel transmittance (H0 ′) and the direct transmittance (H90 ′) of the polarizing plate were measured again. The obtained value was applied to the following formula to calculate the polarization degree P500 after 500 hours of forced deterioration treatment.
Polarization degree P500 = [(H0′−H90 ′) / (H0 ′ + H90 ′)] / 2 × 100
And the value of polarization degree P0 and polarization degree P500 which were obtained was applied to the following formula, and the amount of polarization degree change was calculated | required.
Polarization degree change = P0−P500
The light resistance was evaluated based on the following criteria from the amount of change in polarization degree thus obtained. A and B were judged to be at a level where there was no practical problem.
A: Polarization degree change amount is less than 2% B: Polarization degree change amount is 2% or more and less than 10% C: Polarization degree change amount is 10% or more and less than 25% D: Polarization degree change amount is 25% or more

Moisture and heat resistance Two polarizing plate samples having a size of 500 mm × 500 mm were cut out from the obtained polarizing plate and heat-treated at 80 ° C. and 90% RH for 100 hours, respectively. Two polarizing plate samples obtained after the heat treatment were laminated so that the absorption axes were orthogonal to each other. Then, when light is irradiated from one polarizing plate sample side, the length of the white portion generated at the edge portion on the other polarizing plate sample side is measured, and the ratio to the length of one side (500 mm) of the polarizing plate sample Was calculated. The “white-out portion” to be evaluated is the longest among a plurality of white-out portions generated near the center of each of the four edge portions of the polarizing plate sample. The white edge of the edge is caused by the state where the edge of the polarizing plate that does not transmit light in the orthogonal state is in a state of transmitting light, causing a failure in which no image is displayed at the edge of the polarizing plate. The wet heat resistance of the polarizing plate was evaluated based on the following criteria. A and B were judged to be at a level where there was no practical problem.
A: Edge whiteness is less than 5% (a level that is not problematic as a polarizing plate)
B: White outline of edge is 5% or more and less than 10% (a level that is practically not problematic as a polarizing plate)
C: White edge of edge is 10% or more and less than 20% (a level that can be managed as a polarizing plate)
D: Edge blank is 20% or more (a problematic level as a polarizing plate)

Table 3 shows the evaluation results of the polarizing plates obtained in Examples 24-46 and Comparative Examples 9-13.

  As shown in Table 3, the polarizing plates of Examples 24 to 46 including the optical film of the present invention only have higher moisture and heat resistance than the polarizing plates of Comparative Examples 9 to 13 not including the optical film of the present invention. It can be seen that light resistance is also high.

4). Production of liquid crystal display device (Example 47)
A 40-inch display KLV-40J3000 made by SONY was prepared. Then, the polarizing plates on both sides that were previously bonded to the liquid crystal cell were peeled off, and the two polarizing plates 101 that were produced were bonded to both sides of the glass surface of the liquid crystal cell to obtain a liquid crystal display device 101. The two polarizing plates 101 were bonded so that the optical film 101 was in contact with the liquid crystal cell and the absorption axis of the polarizing plate 101 was in the same direction as the absorption axis of the polarizing plate previously bonded.

(Examples 48-69 and Comparative Examples 14-18)
Polarizing plates 102 to 123 and 124 to 128 were obtained in the same manner as in Example 47 except that the polarizing plate 101 was changed as shown in Table 4.

  The front contrast unevenness of the obtained liquid crystal display device and the humidity dependence of the viewing angle were evaluated by the following methods.

Front contrast unevenness The backlight of the obtained liquid crystal display device was lit continuously for one week in an environment of 23 ° C. and 55% RH. Thereafter, using ELZIM EZ-Contrast 160D, the brightness from the normal direction of the display screen when white is displayed on the liquid crystal display device and the brightness from the normal direction of the display screen when black is displayed. Each was measured and applied to the following formula to determine the front contrast.
Front contrast = (brightness of white display measured from normal direction of display device) / (brightness of black display measured from normal direction of display device)

The front contrast at any five points on the display screen of the liquid crystal display device was measured in the same manner. Then, the average value of the five front contrasts obtained was obtained. Further, among the five front contrasts obtained, the maximum value or the minimum value of the front contrast that maximizes the difference (absolute value) from the average value was obtained. These values were applied to the following formula to determine the front contrast variation (%).
Variation in front contrast (%) = | (maximum or minimum value of front contrast) − (average value of front contrast) | / (average value of front contrast) × 100

Front contrast unevenness was evaluated according to the following criteria. A and B were judged to be at a level where there was no practical problem.
A: Variation in front contrast is 0% or more and less than 5%, and unevenness is small B: Variation in front contrast is 5% or more and less than 10%, and unevenness is somewhat C: Variation in front contrast is 10% or more Yes, the unevenness is large

Humidity Dependence of Viewing Angle The viewing angle of the liquid crystal display device after standing for 5 hours in an environment of 23 ° C. and 55% RH was measured using EZ-Contrast 160D manufactured by ELDIM. Next, the liquid crystal display device was left in an environment of 23 ° C. and 20% RH for 5 hours, and then the viewing angle was measured. Further, this liquid crystal display device was left in an environment of 23 ° C. and 80% RH for 5 hours, and then the viewing angle was measured. Finally, the liquid crystal display device was left in an environment of 23 ° C. and 55% RH for 5 hours, and then the viewing angle was measured. Then, the viewing angle measured in the first environment at 23 ° C. and 55% RH was compared with the viewing angle measured in the last environment at 23 ° C. and 55% RH, and the amount of variation in viewing angle was measured. . A and B were judged to be at a level where there was no practical problem.
A: No change in viewing angle is observed. B: Some variation in viewing angle is observed. C: A change in viewing angle is observed. D: A change in viewing angle is noticeable.

Table 4 shows the evaluation results of the liquid crystal display devices obtained in Examples 47 to 69 and Comparative Examples 14 to 18.

  As shown in Table 4, the liquid crystal display devices of Examples 47 to 69 including the optical film of the present invention were more uneven in front contrast than the liquid crystal display devices of Comparative Examples 14 to 18 not including the optical film of the present invention. It can be seen that the viewing angle is less dependent on humidity.

  The optical film of the present invention has high retardation, and has high heat and humidity resistance and brittleness. Therefore, the polarizing plate including the optical film of the present invention has good light resistance and moisture and heat resistance, and the liquid crystal display device can reduce the front contrast unevenness and the humidity dependence of the viewing angle.

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 20 Liquid crystal cell 40 1st polarizing plate 42 1st polarizer 44 Polarizing plate protective film (F1)
46 Polarizing plate protective film (F2)
60 Second polarizing plate 62 Second polarizer 64 Polarizing plate protective film (F3)
66 Polarizing plate protective film (F4)
80 Backlight

Claims (11)

An optical film containing a cellulose ester and a compound represented by the following general formula (1).
General formula (1)

(Where
L ₁₁ represents a single bond or —NR ₁ — (R ₁ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group);
A ₁₁ represents an aryl group, an aryl-containing alkyl group, an aryl-containing alkenyl group, a heteroaryl group, a heteroaryl-containing alkyl group, or a heteroaryl-containing alkenyl group ;
L ₁₂ is a single bond, —NR ₂ — (R ₂ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group), —O—, —S—, —C (═O) —, —NR ₄ C (═O) — (R ₄ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group) or —SO ₂ —;
A ₁₂ represents an aryl-containing group, heteroaryl-containing group or cycloalkyl group;
L ₁₃ is a single bond, —NR ₃ — (R ₃ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group), —O—, —S—, —C (═O) —, —NR ₅ C (═O) — (R ₅ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group) or —SO ₂ —;
A ₁₃ represents an aryl-containing group, a heteroaryl-containing group, a cycloalkyl group, or a hydrogen atom;
R ₁₂ represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an aryl group or an acylamino group) In A ₁₂ and A ₁₃ of the general formula (1),
The aryl-containing group is an aryl group, an aryl-containing alkyl group or an aryl-containing alkenyl group;
The heteroaryl-containing group is a heteroaryl group, a heteroaryl-containing alkyl group, or a heteroaryl-containing alkenyl group.
The optical film according to claim 1. The optical film according to claim 1, wherein A _{13 in the} general formula (1) is an aryl-containing group, a heteroaryl-containing group, or a cycloalkyl group. The said cellulose ester is an optical film as described in any one of Claims 1-3 which satisfy | fills following formula (a) and (b).
Formula (a) 1.5 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(Wherein X represents the degree of substitution of the acetyl group, Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof)   The optical film according to claim 4, wherein Y in the formula (b) is 0 in the cellulose ester.   The optical film as described in any one of Claims 1-5 whose thickness of the said optical film is 20-60 micrometers. The retardation Ro at a wavelength of 590 nm represented by the following formula (I) is 20 to 150 nm, and the Rth at a wavelength of 590 nm represented by the following formula (II) is 70 to 300 nm. The optical film as described in any one of -6.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx represents the refractive index in the direction x where the refractive index is maximum in the in-plane direction of the optical film;
ny represents the refractive index in the direction y perpendicular to the direction x in the in-plane direction of the optical film;
nz represents the refractive index in the thickness direction z of the optical film;
d (nm) represents the thickness of the optical film) A polarizer,
The optical film according to any one of claims 1 to 7, disposed on at least one surface of the polarizer,
A polarizing plate. A liquid crystal display device comprising a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell,
At least one is a liquid crystal display device containing a polarizer and the optical film as described in any one of Claims 1-7 arrange | positioned in the at least one surface of the said polarizer among a pair of said polarizing plates.   The liquid crystal display device according to claim 9, wherein the optical film is disposed on a surface of the polarizer on the liquid crystal cell side. The liquid crystal cell has a pair of transparent substrates facing each other, and a liquid crystal layer sandwiched between the pair of transparent substrates and containing a positive type liquid crystal,
Among the pair of transparent substrates, a plurality of electrodes for applying a voltage to the positive liquid crystal is disposed on one transparent substrate,
The positive type liquid crystal is aligned vertically to the transparent substrate when no voltage is applied, and is aligned horizontally to the transparent substrate by an electric field generated between the plurality of electrodes when a voltage is applied. 10. A liquid crystal display device according to 10.

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