JP5962664B2 - Optical compensation film, polarizing plate and liquid crystal display device - Google Patents

Description

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

  Liquid crystal display devices are widely used as thin displays such as televisions. There are various methods for driving the liquid crystal in the liquid crystal display device. Among them, as a liquid crystal display device used for a large television, a vertical alignment type liquid crystal display device is used because of its high contrast.

  As a vertical alignment type liquid crystal display device, for example, a VA liquid crystal display device is known (for example, Patent Document 1). In addition, in order to improve the viewing angle and oblique color of a VA liquid crystal display device, a liquid crystal display device having an optical compensation film exhibiting reverse wavelength dispersion has been proposed (for example, Patent Document 2).

  In recent years, vertical alignment type liquid crystal display devices are required to have high transmittance as power consumption is reduced. In particular, it is known that it is effective to increase Δnd of the liquid crystal cell included in the liquid crystal display device in order to increase the transmittance of the vertical alignment type liquid crystal display device. That is, a liquid crystal cell having a large Δnd exhibits a large phase difference when a voltage is applied to align liquid crystal molecules in the horizontal direction with respect to the substrate surface. Therefore, when white is displayed by applying a voltage to the liquid crystal cell, the polarization state of the light transmitted through the polarizer on the backlight side can be sufficiently changed by the horizontally aligned liquid crystal molecules, The amount of light transmitted through the polarizer can be increased.

JP 2000-131893 A International Publication No. 2009/113208

  However, a vertical alignment type liquid crystal display device having a liquid crystal cell having a large Δnd has a problem that the viewing angle and the color tone in an oblique direction cannot be improved by a conventional optical compensation film. In other words, in order to improve the viewing angle and the color tone in the oblique direction of the vertical alignment type liquid crystal display device having a liquid crystal cell having a large Δnd, a new optical compensation suitable for the vertical alignment type liquid crystal cell having a large Δnd. A film was needed.

  The present invention has been made in view of the above circumstances, and includes an optical compensation film, a polarizing plate, and the like that are suitable for a vertical alignment type liquid crystal cell having a large Δnd and can improve the viewing angle and the color tone in an oblique direction. An object is to provide a liquid crystal display device.

（一般式（１Ａ）中、
Ｌ^１およびＬ^２は、それぞれ独立に単結合または下記式で表される二価の連結基を表し；

Ａ^１およびＡ^２は、それぞれ独立に−Ｏ−、−ＮＲ−（Ｒは水素原子または置換基）、−Ｓ−または−ＣＯ−を表し；
Ｒ^１〜Ｒ^５は、それぞれ独立に置換基を表す）
［４］ 前記糖エステル化合物は、下記式（６）で表される化合物である、［３］に記載の光学補償フィルム。

（一般式（６）のＲ_１〜Ｒ_８は、置換もしくは無置換のアルキルカルボニル基、または置換もしくは無置換のアリールカルボニル基を表し；Ｒ_１〜Ｒ_８は、互いに同じであっても、異なってもよい）
［５］ 前記一般式（１Ａ）で表される化合物の含有量は、前記セルロースエステルに対して０．１〜３０質量％である、［３］に記載の光学補償フィルム。
［６］ 前記糖エステル化合物の含有量は、前記セルロースエステルに対して１〜４０質量％である、［３］または［４］に記載の光学補償フィルム。
［７］ 前記光学補償フィルムが、下記式（５）をさらに満たす、［１］〜［６］のいずれかに記載の光学補償フィルム。
式（５） １．０≦Ｒｔｈ（４５０）/Ｒｔｈ（６５０）
［８］ 前記光学補償フィルムの厚みが、２５〜１００μｍである、［１］〜［７］のいずれかに記載の光学補償フィルム。[1] An optical compensation film containing a cellulose ester, wherein the optical compensation film is defined by the following formula (I) at 23 ° C. and 55% RH and measured at a measurement wavelength of 450 nm, 550 nm, or 650 nm. The retardation in the in-plane direction is defined as R0 (450), R0 (550), or R0 (650), respectively, and is defined by the following formula (II), and is measured at a measurement wavelength of 450 nm, 550 nm, or 650 nm. An optical compensation film satisfying the following formulas (1) to (4) when Rth (450), Rth (550) or Rth (650).
Formula (1) 0.7 <R0 (450) / R0 (650) <Rth (450) / Rth (650) <2
Formula (2) R0 (450) / R0 (650) <1.0
Formula (3) 40 nm <R0 (550) <80 nm
Formula (4) 100 nm <Rth (550) <260 nm
Formula (I): R0 = (nx−ny) × t (nm)
Formula (II): Rth = {(nx + ny) / 2−nz} × t (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the optical compensation film;
ny represents the refractive index in the direction y orthogonal to the slow axis direction x in the in-plane direction of the optical compensation film;
nz represents the refractive index in the thickness direction z of the optical compensation film;
t (nm) represents the thickness of the optical compensation film)
[2] The optical compensation film according to [1], wherein the cellulose ester has a total acyl group substitution degree of 1.5 to 3.0 and an acetyl group substitution degree of 0 to 2.5.
[3] The method according to [1] or [2], including one or more selected from the group consisting of a compound represented by the general formula (1A), a sugar ester compound, a phosphate ester plasticizer, and a glycolate plasticizer. Optical compensation film.

(In the general formula (1A),
L ¹ and L ² each independently represent a single bond or a divalent linking group represented by the following formula;

A ¹ and A ² each independently represent —O—, —NR— (R represents a hydrogen atom or a substituent), —S— or —CO—;
R ^{1 to} R ⁵ each independently represents a substituent)
[4] The optical compensation film according to [3], wherein the sugar ester compound is a compound represented by the following formula (6).

(R _{1 to} R _{8 in} the general formula (6) represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group; R _{1 to} R ₈ may be the same or different from each other. May be)
[5] The optical compensation film according to [3], wherein the content of the compound represented by the general formula (1A) is 0.1 to 30% by mass with respect to the cellulose ester.
[6] The optical compensation film according to [3] or [4], wherein the content of the sugar ester compound is 1 to 40% by mass with respect to the cellulose ester.
[7] The optical compensation film according to any one of [1] to [6], wherein the optical compensation film further satisfies the following formula (5).
Formula (5) 1.0 ≦ Rth (450) / Rth (650)
[8] The optical compensation film according to any one of [1] to [7], wherein the thickness of the optical compensation film is 25 to 100 μm.

[9] A polarizer and the optical compensation film according to any one of [1] to [8] disposed on at least one surface of the polarizer, the absorption axis of the polarizer and the optical compensation film A polarizing plate in which the slow axis of each is orthogonal.
[10] A liquid crystal display device having, in order, a first polarizing plate having a first polarizer, a liquid crystal cell, and a second polarizing plate having a second polarizer, A pair of opposing substrates; and a liquid crystal layer sandwiched between the pair of substrates and including liquid crystal, and the liquid crystal cell, when no voltage is applied, causes the liquid crystal to be perpendicular to the pair of substrate surfaces, When the voltage is applied, the liquid crystal is aligned in a direction parallel to the pair of substrate surfaces, and the gap of the liquid crystal cell is d (nm), and the refractive index of the liquid crystal at 23 ° C. and a measurement wavelength of 550 nm. When anisotropy is Δn, 320 nm <Δnd <470 nm is satisfied, and either one or both of the first polarizing plate and the second polarizing plate are the first polarizer or the second polarizing plate. Placed on the liquid crystal cell side surface of the polarizer A liquid crystal display device comprising the optical compensation film according to any one of [1] to [8].
[11] Both the first polarizing plate and the second polarizing plate have the optical compensation film disposed on the liquid crystal cell side surface of the first polarizer or the second polarizer. The liquid crystal display device according to [10].

  A liquid crystal display device having the optical compensation film of the present invention and a vertical alignment type liquid crystal cell having a large Δnd has high transmittance or response speed, and can improve the viewing angle and the color in the oblique direction.

It is a schematic diagram which shows the basic composition of one Embodiment of the liquid crystal display device which concerns on this invention. It is a top view which shows an example of the substrate surface of the liquid crystal cell which has a multi domain structure. It is a schematic diagram which shows the structure I of the liquid crystal display device of an Example. It is a schematic diagram which shows the structure II of the liquid crystal display device of an Example. It is a schematic diagram which shows the structure III of the liquid crystal display device of an Example.

1. Optical Compensation Film The optical compensation film of the present invention contains a transparent thermoplastic resin, and may further contain additives such as a wavelength dispersion adjusting agent as necessary.

  Examples of the transparent thermoplastic resin include cellulose ester, cyclic olefin resin, (meth) acrylic resin, chain olefin resin, polyethylene terephthalate resin, and the like, and preferably cellulose ester.

Cellulose ester Cellulose ester is a compound obtained by esterifying a hydroxyl group of cellulose with an aliphatic carboxylic acid or an aromatic carboxylic acid.

  The acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group. Examples of the aliphatic acyl group are acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert-butanoyl group, oleoyl group and cinnamoyl group. Examples of the aromatic acyl group include a benzoyl group and a naphthylcarbonyl group. Of these, an aliphatic acyl group having 2 to 4 carbon atoms such as an acetyl group, a propionyl group, and a butanoyl group is preferable.

  The total acyl group substitution degree of the cellulose ester is preferably 1.5 to 3.0, and more preferably 2.0 to 2.8. This is because it is easy to obtain a film having an appropriate retardation and good wavelength dispersion.

The cellulose ester preferably satisfies the following formulas (i) and (ii) simultaneously when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y.
Formula (i) 1.5 ≦ X + Y ≦ 3.0
Formula (ii) 0 ≦ X ≦ 2.5

  R0 wavelength dispersion (R0DSP = R0 (450) / R0 (650)) and Rth wavelength dispersion (RthDSP = Rth (450) / Rth (650)) of the film to be described later are, for example, the total acyl group substitution degree of the cellulose ester. And the degree of acetyl group substitution.

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

  Examples of cellulose esters include cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate or cellulose phthalate, preferably cellulose triacetate, Examples thereof include cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate. The cellulose ester may be one type or a mixture of two or more types.

In order to obtain a film having high mechanical strength, the number average molecular weight of the cellulose ester is preferably in the range of 3.0 × 10 ^{4 to} 2.0 × 10 ⁵ , and 4.0 × 10 ⁴ to 1. More preferably, it is in the range of 6 × 10 ⁵ . The number average molecular weight of the cellulose ester can be measured by gel permeation chromatography (GPC).

  The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the cellulose ester is preferably 1.5 to 5.5, more preferably 2.0 to 5.0, and more preferably 2.5 to 5. 0.0 is more preferable, and 3.0 to 5.0 is particularly preferable.

  The molecular weight and molecular weight distribution of the cellulose ester can be measured by high performance liquid chromatography.

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.

  1 g of cellulose ester is added to 20 ml of pure water (electric conductivity 0.1 μS / cm or less, pH 6.8), and the pH of the solution obtained by stirring in a nitrogen atmosphere at 25 ° C. for 1 hr is 6-7. It is preferable that the electric conductivity is 1 to 100 μS / cm.

  Cellulose esters can be synthesized by known methods. Specifically, cellulose is esterified in the presence of a catalyst (such as sulfuric acid) with a C3 or higher organic acid containing at least acetic acid or an anhydride thereof or an anhydride thereof to obtain a cellulose triester. Synthesize. Subsequently, the cellulose triester is hydrolyzed to synthesize a cellulose ester having a desired degree of acyl substitution. The obtained cellulose ester can be filtered, precipitated, washed with water, dehydrated and dried to obtain a cellulose ester (see the method described in JP-A-10-45804).

  Examples of cellulose used as a raw material include cotton linter, wood pulp (derived from conifers and hardwoods), kenaf and the like. The wood pulp is preferably derived from conifers. In order to improve the peelability of the film formed, cellulose derived from cotton linter is preferred.

  The cellulose used as a raw material may be only one type or a mixture of two or more types. For example, the ratio of cellulose derived from cotton linter: cellulose derived from wood pulp (coniferous): cellulose derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50. : 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  The optical compensation film of the present invention has a wavelength dispersion adjusting agent, a sugar ester compound, and a plasticizer (preferably a phosphate ester plasticizer and a glycolate plasticizer) in order to develop specific wavelength dispersion characteristics as described later. It is preferable to further contain one or more selected from the group consisting of These additives may be used alone or in combination of two or more.

Wavelength dispersion adjusting agent The wavelength dispersion adjusting agent is preferably a compound having an absorption maximum in the wavelength range of 250 nm to 400 nm in the light absorption spectrum, and more preferably a compound having an absorption maximum in the wavelength range of 270 nm to 380 nm. A compound having an absorption maximum in a wavelength range of 330 nm to 370 nm is more preferable. The wavelength dispersion adjusting agent is not particularly limited, and may be one that imparts reverse wavelength dispersion or one that imparts forward wavelength dispersion.

Examples of the wavelength dispersion adjusting agent include compounds represented by the following general formulas (1) to (3). These compounds may be liquid crystal compounds.

L ¹ and L ^{2 in} the general formula (1) each independently represent a single bond or a divalent linking group. Examples of the divalent linking group include the following, more preferably —O—, —COO—, and —OCO—.

A ¹ and A ^{2 in} the general formula (1) each independently represent —O—, —NR— (where R is a hydrogen atom or a substituent), —S— or —CO—, preferably —O—, — NR- (R is a substituent) or -S-. The substituent represented by R in —NR— may be an alkyl group having 1 to 30 carbon atoms.

R ^{1 in the} general formula (1) represents a substituent. Examples of the substituent represented by R ¹ include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom);
An alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group);
A cycloalkyl group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, for example, a cyclohexyl group, a cyclopentyl group, a 4-n-dodecylcyclohexyl group);
Bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms. For example, bicyclo [ 1,2,2] heptan-2-yl group, bicyclo [2,2,2] octane-3-yl group);
An alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, such as a vinyl group or an allyl group);
A cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, that is, a monovalent group in which one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms has been removed. Cyclopenten-1-yl, 2-cyclohexen-1-yl group);
Bicycloalkenyl group (substituted or unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom of a bicycloalkene having one double bond. For example, a bicyclo [2,2,1] hept-2-en-1-yl group, a bicyclo [2,2,2] oct-2-en-4-yl group);
An alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, such as an ethynyl group or a propargyl group);
An aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, for example, a phenyl group, a p-tolyl group, a naphthyl group);
Heterocyclic group (preferably a monovalent group obtained by removing one hydrogen atom from a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound, more preferably 3 to 3 carbon atoms. 30 or 5-membered aromatic heterocyclic group such as 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group);
Cyano group, hydroxyl group, nitro group, carboxyl group,
An alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, an n-octyloxy group or a 2-methoxyethoxy group);
An aryloxy group (preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as a phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetra Decanoylaminophenoxy group);
A silyloxy group (preferably a silyloxy group having 3 to 20 carbon atoms, for example, a trimethylsilyloxy group, a tert-butyldimethylsilyloxy group);
A heterocyclic oxy group (preferably a substituted or unsubstituted heterocyclic oxy group having 2 to 30 carbon atoms, 1-phenyltetrazole-5-oxy group, 2-tetrahydropyranyloxy group);
An acyloxy group (preferably a substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms such as formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group; preferably benzoyloxy group, p-methoxyphenylcarbonyl A substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms such as an oxy group);
A carbamoyloxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms such as N, N-dimethylcarbamoyloxy group, N, N-diethylcarbamoyloxy group, morpholinocarbonyloxy group, N, N -Di-n-octylaminocarbonyloxy group, Nn-octylcarbamoyloxy group);
An alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group, a tert-butoxycarbonyloxy group, or an n-octylcarbonyloxy group);
Aryloxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms such as phenoxycarbonyloxy group, p-methoxyphenoxycarbonyloxy group, pn-hexadecyloxyphenoxycarbonyl Oxy group);
An amino group (preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted anilino group having 6 to 30 carbon atoms, such as an amino group, a methylamino group, a dimethylamino group; Anilino group, N-methyl-anilino group, diphenylamino group);
An acylamino group (preferably a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms such as formylamino group, acetylamino group, pivaloylamino group, lauroylamino group; preferably 6 to 6 carbon atoms such as benzoylamino group; 30 substituted or unsubstituted arylcarbonylamino groups);
Aminocarbonylamino group (preferably a substituted or unsubstituted aminocarbonylamino group having 1 to 30 carbon atoms, such as carbamoylamino group, N, N-dimethylaminocarbonylamino group, N, N-diethylaminocarbonylamino group, morpholino A carbonylamino group);
Alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, such as methoxycarbonylamino group, ethoxycarbonylamino group, tert-butoxycarbonylamino group, n-octadecyloxycarbonylamino group, N -Methyl-methoxycarbonylamino group);
Aryloxycarbonylamino group (preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms such as phenoxycarbonylamino group, p-chlorophenoxycarbonylamino group, mn-octyloxyphenoxycarbonylamino Group);
Sulfamoylamino group (preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms such as sulfamoylamino group, N, N-dimethylaminosulfonylamino group, Nn-octylamino A sulfonylamino group);
An alkylsulfonylamino group or an arylsulfonylamino group (preferably a substituted or unsubstituted alkylsulfonylamino group having 1 to 30 carbon atoms such as a methylsulfonylamino group or a butylsulfonylamino group; preferably a phenylsulfonylamino group, 2, A substituted or unsubstituted arylsulfonylamino group having 6 to 30 carbon atoms such as 3,5-trichlorophenylsulfonylamino group and p-methylphenylsulfonylamino group);
A mercapto group;
An alkylthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms, such as a methylthio group, an ethylthio group, or an n-hexadecylthio group);
An arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms, such as a phenylthio group, a p-chlorophenylthio group, an m-methoxyphenylthio group);
A heterocyclic thio group (preferably a substituted or unsubstituted heterocyclic thio group having 2 to 30 carbon atoms, for example, 2-benzothiazolylthio group, 1-phenyltetrazol-5-ylthio group);
Sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms such as N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N′-phenylcarbamoyl) sulfamoyl group);
A sulfo group;
An alkylsulfinyl group or an arylsulfinyl group (preferably a substituted or unsubstituted alkylsulfinyl group having 1 to 30 carbon atoms such as a methylsulfinyl group and an ethylsulfinyl group; preferably a phenylsulfinyl group and a p-methylphenylsulfinyl group A substituted or unsubstituted arylsulfinyl group having 6 to 30 carbon atoms);
An alkylsulfonyl group or an arylsulfonyl group (preferably a substituted or unsubstituted alkylsulfonyl group having 1 to 30 carbon atoms such as a methylsulfonyl group or an ethylsulfonyl group; preferably a phenylsulfonyl group or a p-methylphenylsulfonyl group) A substituted or unsubstituted arylsulfonyl group having 6 to 30 carbon atoms);
An acyl group (preferably a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms such as acetyl group or formyl group; preferably a substituted or unsubstituted aryl having 7 to 30 carbon atoms such as pivaloylbenzoyl group; Carbonyl group);
Aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, such as phenoxycarbonyl group, o-chlorophenoxycarbonyl group, m-nitrophenoxycarbonyl group, p-tert-butylphenoxy Carbonyl group);
An alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, such as a methoxycarbonyl group, an ethoxycarbonyl group, a tert-butoxycarbonyl group, or an n-octadecyloxycarbonyl group);
Carbamoyl group (preferably a substituted or unsubstituted carbamoyl group having 1 to 30 carbon atoms, such as carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group N- (methylsulfonyl) carbamoyl group);
An arylazo group or a heterocyclic azo group (preferably a substituted or unsubstituted arylazo group having 6 to 30 carbon atoms such as a phenylazo group or a p-chlorophenylazo group; preferably 5-ethylthio-1,3,4-thiadiazole- A substituted or unsubstituted heterocyclic azo group having 3 to 30 carbon atoms such as a 2-ylazo group);
An imide group (preferably an N-succinimide group, an N-phthalimide group);
A phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, such as a dimethylphosphino group, a diphenylphosphino group, a methylphenoxyphosphino group);
A phosphinyl group (preferably a substituted or unsubstituted phosphinyl group having 2 to 30 carbon atoms, such as a phosphinyl group, a dioctyloxyphosphinyl group, a diethoxyphosphinyl group);
A phosphinyloxy group (preferably a substituted or unsubstituted phosphinyloxy group having 2 to 30 carbon atoms, such as a diphenoxyphosphinyloxy group, a dioctyloxyphosphinyloxy group);
A phosphinylamino group (preferably a substituted or unsubstituted phosphinylamino group having 2 to 30 carbon atoms, such as a dimethoxyphosphinylamino group, a dimethylaminophosphinylamino group);
A silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, such as a trimethylsilyl group, a tert-butyldimethylsilyl group, or a phenyldimethylsilyl group) is included. Of these, halogen atoms, alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, hydroxyl groups, carboxyl groups, alkoxy groups, aryloxy groups, acyloxy groups, cyano groups, and amino groups are preferred. A group, an alkoxy group and the like are more preferable.

N in the general formula (1) is the number of R ¹ and represents an integer of 0 to 2, preferably 0 or 1.

R ² and R ^{3 in} the general formula (1) each independently represent a substituent. Examples of the substituent represented by R ² and R ³ include those similar to the substituent represented by R ¹ above, and preferably a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group; More preferred is a substituted or unsubstituted phenyl group, a substituted or unsubstituted cyclohexyl group; further preferred is a phenyl group having a substituent or a cyclohexyl group having a substituent; and particularly preferred is a substituent at the 4-position. A phenyl group or a cyclohexyl group having a substituent at the 4-position.

The substituent of the aryl group (such as phenyl group) or the cycloalkyl group (such as cyclohexyl group) may be the same as the substituent represented by R ¹ , and preferably an aryl group, cycloalkyl group, arylcarbonyloxy group, alkyl group. Such as a carbonyloxy group.

X in the general formula (1) represents a nonmetallic atom belonging to Groups 14-16. = X is preferably = O, = S, = NR or = C (R ⁴ ) R ⁵ . = R in NR, and = ^{C (R 4)} R 4 and ^{R 5} in ^{R 5} each independently represents a substituent, the specific examples include those similar to the substituents which the ^{R 1} represents . A hydrogen atom or a substituent may be further bonded to X.

The compound represented by the general formula (1) is preferably a compound represented by the general formula (1A).

R ⁴ and R ^{5 in} the general formula (1A) each independently represent a substituent, and the same substituents as those represented by R ¹ are included. The substituent represented by R ⁴ and R ⁵ is preferably an electron-withdrawing substituent having Hammett's substituent constant σp of 0 or more, and more preferably an electron-withdrawing substitution having σp of 0 to 1.5. It is a group. Examples of such a substituent include a trifluoromethyl group, a cyano group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a nitro group, and the like. Hammett's substituent constant σp is described, for example, in Naoki Inamoto's “Hammett's Rule-Structure and Reactivity” (Maruzen). R ⁴ and R ⁵ may be bonded to each other to form a ring.

The compound represented by the general formula (1A) is preferably a compound represented by the following general formulas (1A-1) to (1A-3), more preferably a compound represented by (1A-3). is there.

R ^{41 to} R ⁴⁷ in general formula (1A-1), R ^{51 to} R ⁵⁷ in general formula (1A-2), and R ^{71 to} R ^{76 in} general formula (1A-3) are each independently a hydrogen atom. Or the substituent similar to R < ¹ > of the above-mentioned general formula (1) is shown. R ⁴² and R ^{45 in} the general formula (1A-1), R ⁵² and R ⁵⁵ in the general formula (1A-2), and R ⁷¹ and R ⁷⁴ in the general formula (1A-3) are each preferably represented by the general formula ( 1A) is the same as L ¹ -R ¹ and L ² -R ² ; R ⁴⁶ and R ⁴⁷ in general formula (1A-1), R ⁵⁶ and R ⁵⁷ in general formula (1A-2), and general formula R ⁷⁵ and R ^{76 in} (1A-3) are preferably the same as R ⁴ and R ^{5 in} general formula (1A), respectively.

Specific examples of the compound represented by the general formula (1) are shown below.

R ^{11 to} R ¹⁷ in the general formula (2) and R ^{21 to} R ²⁹ in the general formula (3) each independently represent a hydrogen atom or a substituent. The substituent may be the same as the substituent represented by R ^{1 in} the general formula (1).

Examples of the wavelength dispersion adjusting agent include a rod-like compound represented by the general formula (4) and a discotic compound represented by the general formula (5). These compounds may be liquid crystal compounds.
General formula (4): Ar < ¹ > -L < ¹² > -XL < ¹³ > -Ar < ² >.

Ar ¹ and Ar ^{2 in} the general formula (4) each independently represent a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

  The aromatic ring in the aryl group is preferably a benzene ring. The aromatic heterocycle in the heteroaryl group is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles are generally unsaturated. The hetero atom is preferably a nitrogen atom, an oxygen atom or a sulfur atom, more preferably a nitrogen atom or a sulfur atom. The aromatic heterocycle is a furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring or pyrazine ring.

Examples of the substituent that the aryl group or heteroaryl group has include:
A halogen atom (F, Cl, Br, I);
A hydroxyl group;
Carboxyl group;
A cyano group;
An amino group;
An alkylamino group (eg, methylamino group, ethylamino group, butylamino group, dimethylamino group);
A nitro group;
A sulfo group;
A carbamoyl group;
An alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-dimethylcarbamoyl group);
A sulfamoyl group;
An alkylsulfamoyl group (for example, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group);
Ureido group;
Alkylureido groups (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethylureido group);
Alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, t-amyl group, cyclohexyl group, cyclopentyl group);
An alkenyl group (eg, vinyl, allyl, hexenyl);
An alkynyl group (eg, an ethynyl group, a butynyl group);
An acyl group (eg, formyl group, acetyl group, butyryl group, hexanoyl group, lauryl group);
An acyloxy group (eg, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group);
An alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, heptyloxy group, octyloxy group);
An aryloxy group (eg a phenoxy group);
Alkoxycarbonyl groups (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group);
An aryloxycarbonyl group (eg, phenoxycarbonyl group);
An alkoxycarbonylamino group (eg, butoxycarbonylamino group, hexyloxycarbonylamino group);
Alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group);
An arylthio group (eg, phenylthio group);
An alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfonyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group);
An amide group (for example, an acetamide group, a butyramide group, a hexylamide group, a laurylamide group);
Non-aromatic heterocyclic groups (for example, morpholyl group, pyrazinyl group) and the like are included. Of these, halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups are preferred.

L ¹² and L ^{13 in} the general formula (4) each independently represent a divalent linking group composed of —O—CO—, —CO—O—, or a combination thereof.

  X in the general formula (4) represents a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

  The wavelength dispersion adjusting agent contained in the optical compensation film of the present invention may be one type or a mixture of two or more types. When the chromatic dispersion adjusting agent is a mixture of two or more types, it may be a mixture of a chromatic dispersion adjusting agent that imparts reverse wavelength dispersion and a chromatic dispersion adjusting agent that imparts forward wavelength dispersion.

  The content of the wavelength dispersion adjusting agent is preferably 0.1 to 30% by mass and more preferably 0.5 to 20% by mass with respect to the total of the aforementioned thermoplastic resins contained in the optical compensation film. Preferably, it is 1 to 10% by mass.

Sugar ester compound The sugar ester compound is usually added to impart plasticity while maintaining the transparency of the resulting film. In this invention, you may add in order to adjust R0DSP and RthDSP of the film obtained so that it may mention later. The sugar ester compound has a relatively small degree of increasing the wavelength dispersibility of the film to be obtained (forward wavelength dispersion). The sugar ester compound is preferably a compound represented by the following general formula (6).

R _{1 to} R _{8 in} the general formula (6) represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group. R _{1 to} R ₈ may be the same as or different from each other.

  The substituted or unsubstituted alkylcarbonyl group is preferably a substituted or unsubstituted alkylcarbonyl group having 2 to 7 carbon atoms. Examples of the substituted or unsubstituted alkylcarbonyl group include a methylcarbonyl group (acetyl group), an ethylcarbonyl group, a propylcarbonyl group, and the like. Examples of the substituent that the alkyl group has include an aryl group such as a phenyl group.

  The substituted or unsubstituted arylcarbonyl group is preferably a substituted or unsubstituted arylcarbonyl group having 7 to 14 carbon atoms. Examples of the arylcarbonyl group include a phenylcarbonyl group. Examples of the substituent that the aryl group has include an alkyl group such as a methyl group.

Specific examples of the compound represented by the general formula (6) include the following. R in the table represents R _{1 to} R ₈ in the general formula (6).

  The average degree of substitution of the sugar ester compound is preferably 3.0 to 8.0, more preferably 5.0 to 8.0, from the viewpoint of compatibility with the cellulose ester.

  The sugar ester compound may be one kind or a mixture of two or more kinds. The content of the sugar ester compound is preferably 1 to 40% by mass and more preferably 5 to 20% by mass with respect to the total of the thermoplastic resins described above.

Plasticizer The plasticizer can be usually contained for the purpose of imparting flexibility to the obtained film, but in the present invention, it may be contained for the purpose of adjusting R0DSP and RthDSP of the obtained film, as will be described later. Good.

  Examples of plasticizers include polyhydric alcohol ester plasticizers, polycarboxylic acid ester plasticizers (including phthalate ester plasticizers), glycolate plasticizers, and ester plasticizers (fatty acid ester plasticizers). And an acrylic plasticizer. These may be used alone or in combination of two or more. When two or more types are used in combination, at least one type is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is an ester compound (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a 2-20 valent aliphatic 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 kind of monocarboxylic acid may be used, or a mixture of two or more kinds may be used. 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 benzoic acid; one having 1 to 3 alkyl groups or alkoxy groups (for example, methoxy group or ethoxy group) introduced into the benzene ring of benzoic acid (for example, toluic acid); benzene ring Aromatic monocarboxylic acids having two or more (for example, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, etc.) are included, and benzoic acid is preferred.

  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.

  The polycarboxylic acid 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. .

  Examples of polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Contains aliphatic polycarboxylic acids such as fumaric acid, maleic acid, and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid, and citric acid, and suppresses volatilization from the film. For this, oxypolycarboxylic acids are preferred.

  Examples of the alcohol compound include an aliphatic saturated alcohol compound having a straight chain or a side chain, an aliphatic unsaturated alcohol compound having a straight chain or a side chain, an alicyclic alcohol compound, or an aromatic alcohol compound. Carbon number of an aliphatic saturated alcohol compound or an aliphatic unsaturated alcohol compound becomes like this. Preferably it is 1-32, More preferably, it is 1-20, More preferably, it is 1-10. Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like. Examples of the aromatic alcohol compound include benzyl alcohol and cinnamyl alcohol.

  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 ester plasticizer is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. This is because the retardation of the obtained film hardly changes depending on environmental conditions.

  The acid value means the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value is 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.

  It is preferable that content of a plasticizer is 1-40 mass% with respect to the sum total of the above-mentioned thermoplastic resin contained in an optical compensation film. When using a plasticizer for adjustment of wavelength dispersion, the content of the plasticizer is preferably 2 to 15% by mass, more preferably 5 to 10% by mass with respect to the total of the above-described thermoplastic resins. preferable.

  The optical compensation film of the present invention may further contain various additives as necessary. Examples of the additive include an ultraviolet absorber, an antioxidant, a retardation increasing agent, fine particles (matting agent), an acid scavenger, a light stabilizer, an antistatic agent, and a release agent.

Ultraviolet absorber The ultraviolet absorber may be contained for the purpose of enhancing the durability of the film. Depending on the type, the UV absorber may change the R0DSP or RthDSP of the resulting film, and is therefore preferably selected in consideration of them.

  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.

  The light transmittance of the ultraviolet absorber can be measured with a spectrophotometer by a conventional method using a solution obtained by dissolving the ultraviolet absorber in a solvent (for example, dichloromethane, toluene, etc.). The spectrophotometer is, for example, a spectrophotometer UVIDFC-610 manufactured by Shimadzu Corporation, a 330-type self-recording spectrophotometer manufactured by Hitachi, Ltd., a U-3210-type self-recording spectrophotometer, a U-3410-type self-recording spectrophotometer, U A −4000 self-recording spectrophotometer or the like can be used.

  UV absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, polymer UV absorbers, and discs. It may be a compound or the like. In order not to impair the transparency of the obtained film, a benzotriazole ultraviolet absorber and a benzophenone ultraviolet absorber are preferable, and a benzotriazole ultraviolet absorber is more preferable.

  Examples of benzotriazole UV absorbers include 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, 2- (3,5-di-tert- Butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol and the like. Examples of commercially available benzotriazole ultraviolet absorbers include tinuvins such as tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, and tinuvin 328 (manufactured by BASF Japan Ltd.). Examples of benzophenone ultraviolet absorbers include 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, and the like.

  Examples of polymer ultraviolet absorbers include polymer type ultraviolet absorbers described in JP-A-6-148430; examples of discotic compounds include compounds having a 1,3,5 triazine ring. It is.

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

Antioxidant The optical compensation film of the present invention may further contain an antioxidant, for example, in order to prevent deterioration of the cellulose ester 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 film by halogen or phosphoric acid of the phosphoric acid 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 antioxidants include hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and 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%, more preferably 10 to 1000 ppm in terms of a mass ratio with respect to the total resin components contained in the optical compensation film.

Retardation increasing agent The retardation increasing agent is preferably an aromatic compound having at least two aromatic rings. The aromatic ring of the aromatic compound can be an aromatic hydrocarbon ring or an aromatic heterocycle. The aromatic hydrocarbon ring is preferably a 6-membered ring.

  The aromatic heterocycle is preferably unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. The hetero atom is preferably a nitrogen atom, an oxygen atom or a sulfur atom, more preferably a nitrogen atom. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring, 1,3,5-triazine ring and the like.

  Specific examples of the retardation increasing agent include those described in JP-A No. 2004-109410, JP-A No. 2003-344655, JP-A No. 2000-275434, JP-A No. 2000-1111914, JP-A No. 12-275434, and the like. included.

  The aromatic compound may be one type or a mixture of two or more types. The content of the aromatic compound is preferably 0.01 to 20 parts by mass, and 0.05 to 15 parts by mass with respect to a total of 100 parts by mass of the above-described thermoplastic resin contained in the optical compensation film. More preferably, it is 0.1-10 mass parts.

Fine particles (matting agent)
The optical compensation 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 the organic fine particles include silicone resin fine particles, fluororesin fine particles, and acrylic resin fine particles, preferably silicone resin fine particles, and more preferably silicone resin fine particles having a three-dimensional network structure. Among these, in order to reduce the increase in the haze of the obtained film, fine particles containing silicon are preferable, and silicon dioxide is particularly preferable.

  Examples of the fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (which is a commercial product manufactured by Nippon Aerosil Co., Ltd.). Of these, Aerosil 200V and Aerosil R972V are preferred because they have a great effect of reducing the coefficient of friction while keeping the haze of the film low. Examples of the fine particles of zirconium oxide include Aerosil R976 and R811 (trade names manufactured by Nippon Aerosil Co., Ltd.). Examples of the fine particles of the silicone resin include Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.).

  The primary average particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These fine particles may form secondary aggregates having a particle size of 0.05 to 0.3 μm.

  The fine particles are preferably included so that the dynamic friction coefficient of at least one surface of the optical compensation film is 0.2 to 1.0. 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 compensation film.

  The optical compensation film may be composed of a single layer or a plurality of layers. When the optical compensation film is composed of a plurality of layers, at least one layer may be a liquid crystal layer such as an optically anisotropic layer.

Properties of Optical Compensation Film The thickness of the optical compensation film is not particularly limited, but is preferably 20 to 200 μm, more preferably 25 to 100 μm, and further preferably 30 to 80 μm. If the thickness of the film is too small, it is difficult to obtain a desired retardation. On the other hand, if the thickness of the film is too large, the retardation tends to vary due to the influence of humidity and the like.

In order to sufficiently perform optical compensation of a liquid crystal display device including a vertical alignment type liquid crystal cell having a large Δnd, the optical compensation film of the present invention is measured at a measurement wavelength of 450 nm, 550 nm, or 650 nm at 23 ° C. and 55% RH. The retardation in the in-plane direction is R0 (450), R0 (550) or R0 (650), respectively, and the retardation in the thickness direction measured at a measurement wavelength of 450 nm, 550 nm or 650 nm is Rth (450), Rth ( 550) or Rth (650), it is preferable that the following formulas (1) to (4) are simultaneously satisfied.
Formula (1) 0.7 <R0 (450) / R0 (650) <Rth (450) / Rth (650) <2
Formula (2) R0 (450) / R0 (650) <1.0
Formula (3) 40 nm <R0 (550) <80 nm
Formula (4) 100 nm <Rth (550) <260 nm

Retardations R0 and Rth are defined by the following equations, respectively.
Formula (I): R0 = (nx−ny) × t (nm)
Formula (II): Rth = {(nx + ny) / 2−nz} × t (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the optical compensation film;
ny represents the refractive index in the direction y orthogonal to the slow axis direction x in the in-plane direction of the optical compensation film;
nz represents the refractive index in the thickness direction z of the optical compensation film;
t (nm) represents the thickness of the optical compensation film)

The retardations R0 and Rth can be determined by the following method, for example.
1) The obtained optical compensation film is conditioned at 23 ° C. and 55% RH. The average refractive index of the optical compensation film after humidity adjustment is measured with an Abbe refractometer.
2) R0 when light having a measurement wavelength of 450 nm, 550 nm, and 650 nm is incident on the optical compensation film after humidity adjustment from the normal direction of the film is measured with an Axoscan manufactured by Axometrcs.
3) Retardation value R (θ) when Axoscan made by Axometrcs Inc. makes incident light having a measurement wavelength of 450 nm, 550 nm, and 650 nm from an angle θ (incident angle (θ)) with respect to the film normal direction, respectively. Measure. θ can be larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R0 and R (θ) and the above-mentioned average refractive index and film thickness, nx, ny and nz are calculated by Axoscan from Axomercs, and Rth at measurement wavelengths of 450 nm, 550 nm and 650 nm is calculated. Calculate each. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

  R0 (450) / R0 (650) is calculated from the obtained R0 (450) and R0 (650); Rth (450) / Rth (650) is obtained Rth (450) and Rth (650). ).

  In a liquid crystal display device including a vertical alignment type liquid crystal cell, light leakage at the time of black display or a decrease in viewing angle and white color at the time of white display are mainly 1) the liquid crystal cell is birefringent (Δnd). 2) It is considered that this is caused by the fact that the absorption axes of the pair of polarizers are not orthogonal in the oblique direction. Therefore, the optical compensation film usually 1) compensates light leakage due to birefringence (Δnd) of the liquid crystal cell with Rth; 2) light leakage due to orthogonality of the absorption axes of the pair of polarizers R0 It compensates with. Therefore, in order to compensate for light leakage of a liquid crystal cell having a large Δnd, it is considered that Rth of the optical compensation film should be increased.

  However, merely increasing the Rth of the optical compensation film cannot sufficiently improve the viewing angle and oblique color of the liquid crystal display device. That is, in the conventional optical compensation film, the wavelength dispersion of R0 and the wavelength dispersion of Rth are almost the same. However, in a liquid crystal display device including a vertical alignment type liquid crystal cell having a large Δnd, even if a conventional optical compensation film having substantially the same wavelength dispersion of R0 and Rth is used, sufficient optical compensation cannot be performed. It was found. It is presumed that the vertical alignment type liquid crystal cell having a large Δnd has a large liquid crystal fluctuation component at the time of vertical alignment; that is, black display, thereby increasing the light leakage amount of the liquid crystal display device.

  In order to sufficiently perform optical compensation in a liquid crystal display device including a vertically aligned liquid crystal cell having a large Δnd, the wavelength dispersion characteristic of R0 is R0DSP = R0 (450) / R0 (650); the wavelength of Rth When the dispersion characteristic is RthDSP = Rth (450) / Rth (650), it is found that R0DSP <RthDSP; specifically, 0.7 <R0DSP <RthDSP <2 is effective. It was done. In particular, it is more preferable that R0DSP <1 and RthDSP ≧ 1.

  R0DSP and RthDSP of the optical compensation film can be adjusted by, for example, the film composition; specifically, the acyl group substitution degree of the cellulose ester, the type and content of the wavelength dispersion adjusting agent, plasticizer, sugar ester compound, etc. . For example, in order to satisfy R0DSP <RthDSP, select a forward wavelength dispersant that has a higher RthDSP increase than R0DSP; or select a reverse wavelength dispersant that has a lower RthDSP decrease than R0DSP. You can do it. Examples of preferable compounds that can satisfy R0DSP <RthDSP include the compounds represented by the general formula (1) (wavelength dispersion adjusting agent), sugar ester compounds, and the like.

  R0 of the optical compensation film is preferably 40 nm <R0 (550) <80 nm, and more preferably 45 nm <R0 (550) <70 nm. As described above, the Rth of the optical compensation film is preferably moderately high in order to perform optical compensation of a liquid crystal cell having a large Δnd. Specifically, 100 nm <Rth (550) <260 nm is preferable, and 120 nm <Rth (550) <250 nm is more preferable. If R0 and Rth of the optical compensation film are both out of the above range, the viewing angle may not be sufficient.

  R0 and Rth of the optical compensation film can be adjusted by, for example, stretching conditions and film thickness. In order to increase R0, for example, the draw ratio may be increased. In order to increase Rth, for example, the stretching temperature and the stretching ratio may be lowered, or the film thickness of the film may be increased.

  The angle θ1 (orientation angle) formed by the in-plane slow axis of the optical compensation film and the width direction of the film is preferably −5 ° or more and + 5 ° or less, and more preferably −1 ° or more and + 1 ° or less. preferable. The orientation angle θ1 of the optical compensation film can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).

  The haze of the optical compensation film measured according to JIS K-7136 is preferably less than 1.0%, more preferably 0.2% or less, and 0.1% or less. Is more preferable, and 0.05% or less is particularly preferable.

The haze of the optical compensation film can be measured by a method according to JIS K-7136; specifically, the following method.
1) The obtained optical compensation film is conditioned at 23 ° C. and 55% RH for 5 hours or more. Thereafter, dust attached to the film surface is removed with a blower or the like.
2) Next, the haze of the optical compensation film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) under the condition of 23 ° C. and 55% RH. The light source of the haze meter may be a 5V9W halogen sphere, and the light receiving part may be a silicon photocell (with a relative visibility filter).

  The visible light transmittance of the optical compensation film is preferably 90% or more, and more preferably 93% or more. The breaking elongation of the optical compensation film is preferably 10 to 80%, and more preferably 20 to 50%.

2. Method for Producing Optical Compensation Film The optical compensation film of the present invention can be preferably produced by a solution casting method or a melt casting method. Hereinafter, the manufacturing method of the film containing a cellulose ester is demonstrated.

Solution Casting Method The method for producing the optical compensation film of the present invention by the solution casting method is as follows: 1) a step of preparing a dope by dissolving at least the above cellulose ester in a solvent (dope preparation step), and 2) a dope Step of casting on endless metal support (casting step) 3) Step of evaporating solvent from cast dope to form web (solvent evaporation step) 4) Step of peeling web from metal support (Peeling step) 5) A step of drying and stretching the web to obtain a film (drying and stretching step), and 6) a step of winding the obtained film (winding step).

1) Dope preparation step In a dissolution vessel, a dope is prepared by dissolving a thermoplastic resin and, if necessary, an additive in a solvent. The solvent used for preparing the dope is not particularly limited as long as it dissolves a thermoplastic resin such as cellulose ester. Examples of such solvents include chlorinated organic solvents such as methylene chloride; methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2, 2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2- Methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, ethyl lactate, lactic acid, di Non-chlorine organic solvents such as acetone alcohol are included, and methylene chloride, methyl acetate, ethyl acetate, acetone, and ethyl lactate are preferable.

  The solvent used for the preparation of the dope may further contain a solvent other than those described above. Examples of such other solvents include linear or branched aliphatic alcohols having 1 to 4 carbon atoms. Examples of linear or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like, Ethanol is preferred because it has a relatively low boiling point and is easy to dry.

  The content of the other solvent may be 1 to 40% by mass with respect to the whole solvent. When the content ratio of the other solvent is increased, the resulting web is easily gelled, and thus easily peeled from the metal support. On the other hand, when the content ratio of the other solvent in the dope is lowered, the thermoplastic resin is easily dissolved when the solvent is a non-chlorine organic solvent.

  The content of the thermoplastic resin in the dope containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms as the solvent is preferably 10 to 45% by mass.

  The thermoplastic resin is dissolved at normal pressure, at a temperature lower than the boiling point of the main solvent, at a temperature higher than the boiling point of the main solvent and under pressure, Japanese Patent Application Laid-Open No. 9-95544, Japanese Patent Application Laid-Open No. 9-95557, or Japanese Patent Application Laid-Open No. The method may be a method performed by a cooling dissolution method described in JP-A-9-95538, a method performed under high pressure described in JP-A No. 11-21379, and a method performed more than the boiling point of the main solvent and under pressure is particularly preferable.

  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.

2) Casting process The dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and applied onto an endless metal support (for example, a stainless steel belt or a rotating metal drum). Cast from the slit of the pressure die.

  The die is preferably a pressure die that can adjust the slit shape of the die portion and easily adjust the film thickness uniformly. Examples of the pressure die include a coat hanger die and a T-die. The surface of the metal belt is preferably mirror-finished.

3) Solvent evaporation step The web (dope film obtained by casting the dope on a metal support) is heated on the metal support to evaporate the solvent. The web is preferably dried in an atmosphere of 40 to 100 ° C. In order to dry the web in an atmosphere of 40 to 100 ° C., it is preferable to apply hot air of 40 to 100 ° C. to the web surface or to heat it with infrared rays or the like.

  As a method for evaporating the solvent, there are a method in which air is applied to the surface of the web, a method in which heat is transferred from the back surface of the belt by liquid, a method in which heat is transferred from the front and back by radiant heat, etc. A method in which heat is transferred from the back surface with a liquid is preferable.

4) Peeling process The web in which the solvent has evaporated on the metal support is peeled off at the peeling position. The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

The residual solvent amount of the web at the time of peeling at the peeling position on the metal support is preferably 50 to 120% by mass, although it depends on the drying conditions and the length of the metal support. A web having a large amount of residual solvent is too soft and tends to impair flatness, and is liable to cause slippage and vertical stripes due to peeling tension. The residual solvent amount of the web at the peeling position can be set so that such slippage and vertical stripes can be suppressed.
The amount of residual solvent in the web is defined by the following formula.
Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
The heat treatment for measuring the residual solvent amount means a heat treatment at 115 ° C. for 1 hour.

  The peeling tension at the time of peeling the web from the metal support is usually 196 to 245 N / m, but it is preferably 190 N / m or less when wrinkles easily occur at the time of peeling. m or less is more preferable, 137.2 N / m or less is more preferable, and 100 N / m or less is further preferable.

  The web temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and further preferably 15 to 30 ° C.

5) Drying and stretching step The web obtained by peeling from the metal support is dried and then stretched. For drying the web, the web may be dried while being transported by a large number of rolls arranged vertically, or may be dried while being transported while fixing both ends of the web with clips.

  The method for drying the web may be a method of drying with hot air, infrared rays, a heating roll, microwave, or the like, and a method of drying with hot air is preferable because it is simple. The drying temperature of the web is 40 to 250 ° C, preferably 40 to 160 ° C. Drying at high temperature is preferably carried out with the residual solvent amount of the web being 8% by mass or less.

  By stretching the web, an optical compensation film having a desired retardation is obtained. The retardation of the optical compensation film can be controlled by adjusting the magnitude of the tension applied to the web at least in the width direction of the web.

  The web may be stretched at least in the width direction (TD direction) of the web, and may be uniaxial stretching or biaxial stretching. Further, the web may be stretched in an oblique direction with respect to the web width direction or the conveyance direction (MD direction). Biaxial stretching includes stretching in both the web width direction and the transport direction. Biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching.

Sequential biaxial stretching includes a method in which stretching in different stretching directions is sequentially performed, a method in which stretching in the same direction is performed in multiple stages, and the like. Examples of sequential biaxial stretching include the following stretching steps.
Stretch in transport direction-Stretch in width direction-Stretch in transport direction-Stretch in transport direction Stretch in width direction-Stretch in width direction-Stretch in transport direction-Stretch in transport direction

  Simultaneous biaxial stretching also includes a mode in which stretching is performed in one direction and the tension in the other direction is relaxed and contracted. The stretching ratio in the case of simultaneous biaxial stretching is preferably 1.01 to 1.5 times in both the width direction and the casting direction.

  The web stretching method is not particularly limited, and a method is used in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the web conveyance direction (roll stretching method), and both ends of the web are clipped. Fix with clips and pins, widen the gap between the clips and pins toward the web conveyance direction and stretch in the conveyance direction, widen in the width direction and stretch in the width direction, or stretch in the width direction and the conveyance direction at the same time And the like (tenter stretching method). These stretching methods may be combined.

  The residual solvent amount of the web at the start of tenter stretching is preferably 20 to 100% by mass. Further, the residual solvent amount of the web after tenter stretching is preferably 10% by mass or less, and more preferably 5% by mass or less.

  The web stretching temperature is preferably 30 to 160 ° C, more preferably 50 to 150 ° C, and further preferably 70 to 140 ° C. In order to improve the uniformity of the obtained optical compensation film, it is preferable that the temperature distribution in the width direction of the atmosphere in the tenter stretching step is small, and the temperature distribution in the width direction is preferably within ± 5 ° C., and ± 2 ° C. Is more preferably within ± 1 ° C.

  The tenter stretching device is preferably capable of independently controlling the web grip length (distance from the start of gripping to the end of gripping) on the left and right. Moreover, it is preferable that a tenter process has a different temperature area | region, or has a neutral zone between different temperature areas, in order to improve the planarity of the optical compensation film obtained.

6) Winding process The film obtained by extending | stretching a web is wound up with a winder. The residual solvent amount of the film to be wound is preferably 2% by mass or less, more preferably 0.4% by mass or less, and further preferably 0.10% by mass or less in order to improve dimensional stability. is there.

  The winding method is not particularly limited, and includes a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  The obtained optical compensation film is a long film and usually has a length of about 100 m to 10000 m. Moreover, it is preferable that the width | variety of an optical compensation film is 1.3-4 m, and it is more preferable that it is 1.4-2.5 m.

Melt Casting Method The method of producing the optical compensation film of the present invention by the melt casting method is as follows: 1) a step of producing a molten pellet (pelletizing step), 2) a step of melt-kneading and extruding the molten pellet (melt extrusion) Step), 3) a step of cooling and solidifying the molten resin to obtain a web (cooling and solidification step), and 4) a step of stretching the web (stretching step).

1) Pelletization process It is preferable that the resin composition containing the thermoplastic resin constituting the optical compensation film of the present invention is previously kneaded and pelletized. Pelletization can be performed by a known method. For example, a resin composition containing the above-described thermoplastic resin and, if necessary, an additive such as a plasticizer is melt-kneaded in an extruder, and then die-molded. Extruded into strands. The molten resin extruded in a strand shape can be cooled with water or air, and then cut to obtain pellets.

  In order to prevent decomposition, the raw material of the pellet is preferably dried before being supplied to the extruder. For example, since a cellulose ester as a thermoplastic resin is easy to absorb moisture, it is preferable to dry at 70 to 140 ° C. for 3 hours or more so that the moisture content is 200 ppm or less, preferably 100 ppm or less.

The mixture of the antioxidant and the thermoplastic resin may be mixed with each other; the antioxidant dissolved in the solvent may be impregnated into the thermoplastic resin; and the antioxidant may be mixed. You may spray and mix in a thermoplastic resin. A vacuum nauter mixer or the like is preferable because the raw materials can be dried and mixed at the same time. Further, the atmosphere around the feeder portion of the extruder and the outlet portion of the die is preferably an atmosphere of dehumidified air or N ₂ gas in order to prevent deterioration of the raw material of the pellet.

  In an extruder, it is preferable to knead at a low shearing force or at a low temperature so as not to cause deterioration of the resin (decrease in molecular weight, coloring, gel formation, etc.). For example, when kneading with a twin-screw extruder, it is preferable to use a deep groove type screw and rotate the two screws in the same direction. In order to knead uniformly, it is preferable that two screw shapes mesh with each other.

  The optical compensation film of the present invention may be produced by pelletizing a resin composition containing a thermoplastic resin and melt-kneading it with an extruder using a thermoplastic resin that has not been melt-kneaded as a raw material.

2) Melt extrusion process The obtained molten pellets and other additives as required are supplied from the hopper to the extruder. The supply of pellets is preferably performed under vacuum, reduced pressure, or an inert gas atmosphere in order to prevent oxidative decomposition of the pellets. Then, in an extruder, the molten pellets and, if necessary, other additives (film material) are melt-kneaded.

  The melting temperature of the film material in the extruder is preferably in the range of Tg ° C to (Tg + 100) ° C, more preferably (Tg ° C) when the glass transition temperature of the film is Tg ° C, although it depends on the type of film material. It is the range of Tg + 10) ° C. to (Tg + 90) ° C. The residence time of the film material in the extruder is preferably 5 minutes or less. The residence time can be adjusted by the number of rotations of the screw, the depth of the groove, L / D which is the ratio of the cylinder length (L) to the cylinder inner diameter (D), and the like.

  The molten resin extruded from the extruder is filtered through a leaf disk filter or the like as necessary, and further mixed with a static mixer or the like, and extruded from a die into a film. The melting temperature Tm of the resin at the exit portion of the die can be about 200 to 300 ° C.

  If foreign matter such as scratches or plasticizer aggregates adheres to the inner wall surface of the die, streaky defects (die lines) may occur on the surface of the extruded molten resin. In order to reduce surface defects such as die lines, the inner wall surface from the extruder to the tip of the die should have a structure in which the resin staying part is difficult to adhere; for example, the inner wall surface from the extruder to the tip of the die. Is preferably free from scratches.

  In order to make it difficult for the molten resin to adhere to the inner wall surface of an extruder, die, or the like, it is preferable that surface treatment is performed to reduce the surface roughness or the surface energy. Examples of such surface processing include processing for polishing to have a surface roughness of 0.2 S or less after hard chrome plating or ceramic spraying.

3) Cooling and solidifying step The resin extruded from the die is nipped between the cooling roll and the elastic touch roll to make the film-like molten resin a predetermined thickness. Then, the film-like molten resin is cooled stepwise with a plurality of cooling rolls and solidified.

  The surface temperature Tr1 of the cooling roll can be Tg (° C.) or lower when the glass transition temperature of the obtained film is Tg (° C.). The surface temperatures of the plurality of cooling rolls may be different. The film surface temperature Tt on the elastic touch roll side can be (Tr1-50) ° C. ≦ Tt ≦ (Tr1-5) ° C.

  The cooling roll is a high-rigidity metal roll and has a structure in which a temperature-controllable medium can be circulated. The material of the surface of the cooling roll can be stainless steel, aluminum, titanium, or the like. The surface of the cooling roll may be subjected to a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, ceramic spraying, etc. in order to make the resin easy to peel off. In order to keep the haze of the film low, the surface roughness Ra of the cooling roll is preferably 0.1 μm or less, and more preferably 0.05 μm or less. The size of the cooling roll only needs to be large enough to cool the extruded film-like molten resin, and the diameter of the cooling roll is usually about 100 mm to 1 m.

  The elastic touch roll is disclosed in JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97 / 028950, JP-A-11-235747, JP-A-2002-36332. For example, a silicon rubber roll covered with a thin-film metal sleeve described in JP-A Nos. 2005-172940 and 2005-280217 is used.

  The film-like molten resin solidified from the cooling roll is peeled off with a peeling roll or the like to obtain a web. When peeling the film-like molten resin, it is preferable to adjust the tension in order to prevent deformation of the resulting web.

4) Stretching process The obtained web is stretched with a stretching machine to obtain a film. The stretching may be performed in at least one direction, and is preferably performed in both the web width direction (TD direction) and the web conveyance direction (MD direction).

  When stretching in both the web width direction (TD direction) and the web conveyance direction (MD direction), the web width direction (TD direction) stretching and the web conveyance direction (MD direction) stretching are sequential. Or may be performed simultaneously.

  The draw ratio can be 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction. When extending in both the web width direction (TD direction) and the web conveyance direction (MD direction), the final direction is 1.01 to 3.0 times, preferably 1.1 to 2.0 times in each direction. It is preferable to do.

  The stretching temperature is preferably Tg to (Tg + 50) ° C. The stretching temperature is preferably uniform in the width direction of the web (TD direction) or the transport direction (MD direction), and the variation in the width direction or transport direction of the web stretching temperature is preferably ± 2 ° C. or less, The temperature is more preferably ± 1 ° C. or less, and further preferably ± 0.5 ° C. or less.

  For stretching the web, a roll stretching machine or a tenter stretching machine can be used. The stretching of the web is preferably performed in the web width direction (TD direction). The web stretched in the width direction has an in-plane slow axis parallel to the width direction. Therefore, in general, a polarizer having an absorption axis parallel to the longitudinal direction (MD direction) of the web and an optical compensation film having an in-plane slow axis parallel to the width direction (TD direction) are roll-to-roll. By laminating, the absorption axis of the polarizer and the in-plane slow axis of the optical compensation film can be easily orthogonalized.

  In order to adjust the retardation of the film obtained after stretching or reduce dimensional change, the film obtained after stretching is shrunk in the transport direction (MD direction) or the width direction (TD direction) as necessary. May be. To shrink the film obtained after stretching in the transport direction (MD direction), for example, release the clip gripped in the width direction and loosen it in the transport direction; gradually reduce the interval between adjacent clips in the transport direction. To relax in the transport direction.

3. Polarizing plate The polarizing plate of the present invention comprises a polarizer and the aforementioned optical compensation film disposed on at least one surface thereof.

  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 compensation film of the present invention may be disposed directly on at least one surface of the polarizer, or may be disposed via another film or layer. The slow axis of the optical compensation film and the absorption axis of the polarizer are orthogonal to each other.

  When the optical compensation film of the present invention is disposed on one surface of the polarizer, the optical compensation film of the present invention may be disposed on the other surface of the polarizer, or other transparent protective film may be provided. It may be arranged. Examples of the transparent protective film include commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-X8 -C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.

  The polarizing plate can be usually obtained through a step of bonding a polarizer and the optical compensation film of the present invention. As an example of the adhesive used for bonding, a completely saponified polyvinyl alcohol aqueous solution or the like 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. At least one of the pair of polarizing plates is a polarizing plate having the optical compensation film of the present invention, and preferably both the pair of polarizing plates are polarizing plates having the optical compensation film of the present invention.

  FIG. 1 is a schematic diagram showing a basic configuration of an embodiment of a liquid crystal display device 10 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 liquid crystal cell 20 may be of a vertical alignment type, such as an OCB (Optically Compensated Birefringence) method, a VA (Vertical Alignment) method (MVA), and a multi-domain vertical alignment or PVA; TN / VA (Twisted Nematic Vertical Alignment) method, TBA (Traverse Bent Alignment) method, and the like.

  The vertically aligned liquid crystal cell 20 includes a pair of substrates and a liquid crystal layer including liquid crystal molecules disposed between them and having negative or positive dielectric anisotropy.

  Of the pair of substrates, the pixel electrode may be provided on one substrate and the counter electrode may be provided on the other substrate; both the pixel electrode and the counter electrode may be provided on one substrate.

  When the pixel electrode is disposed on one transparent substrate and the counter electrode is disposed on the other transparent substrate, the liquid crystal molecules contained in the liquid crystal layer preferably have negative dielectric anisotropy. Examples of liquid crystal molecules having negative dielectric anisotropy include nematic liquid crystal molecules having negative dielectric anisotropy. Examples of nematic liquid crystal molecules having negative dielectric anisotropy include those described in JP-A No. 2004-204133, JP-A No. 2004-250668, JP-A No. 2005-047980, and the like. Specifically, a nematic liquid crystal material having negative dielectric anisotropy and having Δn = 0.0815 and Δε = −4.5 is preferably used.

  When both the pixel electrode and the counter electrode are arranged on one transparent substrate, the liquid crystal molecules contained in the liquid crystal layer preferably have positive dielectric anisotropy. Examples of liquid crystal molecules having positive dielectric anisotropy include nematic liquid crystal molecules having positive dielectric anisotropy. As an example of nematic liquid crystal molecules having positive dielectric anisotropy, liquid crystal materials used in TN type and IPS type liquid crystal display devices can be used. Specifically, a nematic liquid crystal material having a positive dielectric anisotropy and approximately Δn = 0.0815 and Δε = 4.5 is preferably used.

  The liquid crystal layer may further include a chiral material as included in a TN liquid crystal cell as necessary in order to reduce alignment defects of liquid crystal molecules.

  In the liquid crystal cell 20 configured as described above, when no voltage is applied, the major axis of the liquid crystal molecules is aligned vertically with respect to the surfaces of the pair of substrates, and when the voltage is applied, the major axes of the liquid crystal molecules are aligned between the pair of substrates. Orient in a direction parallel to the surface.

  In order to increase the transmittance of the liquid crystal display device, Δnd of the liquid crystal cell 20 is increased; specifically, 320 nm <Δnd <470 nm is preferable, and 410 nm <Δnd <470 nm. More preferred. A liquid crystal cell having a large Δnd exhibits a large phase difference when a voltage is applied to align liquid crystal molecules in the horizontal direction with respect to the substrate surface. Therefore, when white is displayed by applying a voltage to the liquid crystal cell, the polarization state of the light transmitted through the second polarizer (backlight side polarizer) is sufficiently changed by the horizontally aligned liquid crystal molecules. And the amount of light transmitted through the first polarizer (viewing side polarizer) can be increased.

  Δnd of the liquid crystal cell 20 is the product of the refractive index anisotropy Δn of liquid crystal molecules measured at 23 ° C. and 55% RH at a measurement wavelength of 550 nm and the gap d (nm) of the liquid crystal cell. The refractive index anisotropy Δn of the liquid crystal molecules is expressed as an absolute value Δn = | ne−no | of the difference between the ordinary light refractive index no and the extraordinary light refractive index ne of the liquid crystal molecules. The gap d of the liquid crystal cell is specifically the thickness (nm) of the liquid crystal layer.

  Δnd of the liquid crystal cell can be adjusted by, for example, the gap d (nm) of a normal VA liquid crystal cell or the refractive index anisotropy Δn of liquid crystal molecules. For example, in order to increase Δnd of a liquid crystal cell, the gap d (nm) of the liquid crystal cell is increased, the amount of liquid crystal molecules enclosed in the liquid crystal cell is increased, or the liquid crystal having a large refractive index anisotropy Δn. A molecule may be used.

  The liquid crystal cell 20 may have a multi-domain structure. A multi-domain structure refers to a structure in which one pixel of a liquid crystal cell is divided into a plurality of regions. In a liquid crystal cell having a multi-domain structure, the alignment of liquid crystal molecules in the boundary region between the domains can be adjusted. For example, in a VA liquid crystal cell, liquid crystal molecules are inclined during white display. Therefore, in a VA liquid crystal cell that does not have a multi-domain structure, a difference in luminance and color tone tends to occur because the birefringence of liquid crystal molecules differs between the tilt direction and the opposite direction. On the other hand, a VA liquid crystal cell having a multi-domain structure is preferable because the viewing angle characteristics of luminance and color tone are improved.

  FIG. 2 is a plan view showing an example of the substrate surface of the liquid crystal cell 20 having a multi-domain structure. In the figure, one pixel region is shown. As shown in FIG. 2, a pixel electrode 26 having a plurality of slits 24 is disposed on the surface of the substrate 22 on the liquid crystal layer side. The substrate 22 can form a multi-domain structure having four regions 22a, 22b, 22c and 22d having different alignment states of liquid crystal molecules in one pixel region. The width of the pixel electrode 26 sandwiched between the adjacent slits 24 can be about 5 μm.

  The first polarizing plate 40 is disposed on the viewing side, the first polarizer 42, the protective film 44 (F1) disposed on the viewing side surface of the first polarizer 42, and the first A protective film 46 (F2) disposed on the surface of the polarizer 42 on the liquid crystal cell side. The second polarizing plate 60 is disposed on the backlight 80 side, the second polarizer 62, a protective film 64 (F3) disposed on the liquid crystal cell side surface of the second polarizer 62, A protective film 66 (F4) disposed on the backlight side surface of the second polarizer 62; The absorption axis of the first polarizer 42 and the absorption axis of the second polarizer 62 are orthogonal to each other. One of the protective films 46 (F2) and 64 (F3) may be omitted as necessary.

  Of the protective films 44 (F1), 46 (F2), 64 (F3) and 66 (F4), at least one of the protective films 46 (F2) and 64 (F3) disposed on the liquid crystal cell side, preferably both The optical compensation film of the present invention is used.

  Thus, the liquid crystal display device of the present invention has the optical compensation film described above. Therefore, the liquid crystal display device of the present invention can sufficiently perform optical compensation with the above-described optical compensation film, despite having a vertical alignment type cell having a large Δnd. As a result, a liquid crystal display device with high transmittance and response speed, light leakage during black display, and improved viewing angle and oblique color tone during white display can be obtained.

  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. Optical Compensation Film Materials 1) Cellulose Esters The cellulose esters shown in Table 1 were prepared. In Table 1, Dac represents the degree of substitution of the acetyl group, Dpr represents the degree of substitution of the propionyl group, Dbnz represents the degree of substitution of the benzoyl group, and Dall represents the degree of substitution of the total acyl group.

Ｍ２：下記式で表される化合物

Ｍ３：下記式で表される化合物

Ｍ４：チヌビン３２７（チバ・スペシャリティ・ケミカルズ社製）
Ｍ５：トリフェニルホスフェート
Ｍ６：エチルフタリルエチルグリコレート
Ｍ７：チヌビン１７１（チバ・スペシャリティ・ケミカルズ社製）
Ｍ８：チヌビン１０９（チバ・スペシャリティ・ケミカルズ社製）
Ｍ９：ジフェニルビフェニルホスフェート
Ｍ１０：ポリスチレン（Ａｌｄｒｉｃｈ社製 Ｍｗ：８．０）
Ｍ１１：ビフェニルホスフェート
Ｍ１２：下記方法で合成した糖エステル化合物2) Additive M1: Glucose compound A-2 represented by the following formula

M2: Compound represented by the following formula

M3: Compound represented by the following formula

M4: Tinuvin 327 (Ciba Specialty Chemicals)
M5: Triphenyl phosphate M6: Ethylphthalyl ethyl glycolate M7: Tinuvin 171 (manufactured by Ciba Specialty Chemicals)
M8: Tinuvin 109 (Ciba Specialty Chemicals)
M9: Diphenylbiphenyl phosphate M10: Polystyrene (manufactured by Aldrich Mw: 8.0)
M11: Biphenyl phosphate M12: Sugar ester compound synthesized by the following method

Synthesis of sugar ester compound Four-headed Kolben equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet tube was charged with 34.2 g (0.1 mol) of sucrose and 135.6 g (0.6 mol) of benzoic anhydride. ) And 284.8 g (3.6 mol) of pyridine were charged. While stirring these components, nitrogen gas was bubbled from the nitrogen gas inlet tube to raise the temperature, and an esterification reaction was carried out at 70 ° C. for 5 hours.

Next, the inside of the Kolben is depressurized to 4 × 10 ² Pa or less, excess pyridine is distilled off at 60 ° C., the inside of the Kolben is depressurized to 1.3 × 10 Pa or less, and the temperature is raised to 120 ° C. Most of benzoic acid and the produced benzoic acid were distilled off. To the obtained solution, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, stirred at 50 ° C. for 30 minutes, and allowed to stand to separate a toluene layer. To the collected toluene layer, 100 g of water was added, and after washing with water at room temperature for 30 minutes, the toluene layer was collected, and toluene was distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less) to obtain Compound A- A sugar ester compound which is a mixture of 1, A-2, A-3, A-4 and A-5 was obtained.

When the obtained mixture was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS), Compound A-1 was 1.2% by mass, Compound A-2 was 13.2% by mass, and Compound A-3 was The content was 14.2% by mass, Compound A-4 was 35.4% by mass, and Compound A-5 was 40.0% by mass. The average degree of substitution of the mixture was 5.2.

2. Production of optical compensation film (Example 1-1)
Preparation of Fine Particle Dispersion Dilution Liquid A The following components were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin to obtain fine particle dispersion liquid A. The turbidity of the obtained fine particle dispersion was 200 ppm. Next, 75 parts by mass of methylene chloride was further added to the fine particle dispersion A while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to obtain a fine particle dispersion diluent A.
(Composition of fine particle dispersion A)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd., average diameter of primary particles 16 nm, apparent specific gravity 90 g / liter): 10 parts by mass Ethanol: 75 parts by mass

Preparation of Dope Solution A The following components were put into a sealed container and completely dissolved while stirring under heating. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. 24. A dope solution A was obtained. The obtained dope liquid A was further filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the film production line.
(Composition of dope solution A)
Cellulose ester 1 (cellulose acetate propionate, acetyl group substitution degree 1.9, propionyl group substitution degree 0.8, total acyl group substitution degree 2.70, Mn = 70000, Mw = 220,000): 100 parts by weight Fine particle dispersion dilution A: 4 parts by mass Triphenyl phosphate (additive M5): 8 parts by mass Ethylphthalyl ethyl glycolate (additive M6): 2 parts by mass Methylene chloride: 300 parts by mass Ethanol: 60 parts by mass

  The obtained dope solution A was adjusted to 35 ° C. and uniformly cast onto a stainless steel band support with a width of 1800 mm using a belt casting apparatus. The solvent contained in the casting film of the dope liquid A was evaporated on the stainless steel band support until the residual solvent amount reached 100%, and then peeled from the stainless steel band support to obtain a web. The solvent contained in the obtained web was further evaporated at 55 ° C. and then slit to 1650 mm width.

  The obtained web was stretched 1.35 times in the web width direction (TD direction) at 130 ° C. with a tenter stretching machine. When the stretching was started by a tenter stretching machine, the residual solvent amount of the web was 18%.

  While the obtained film was conveyed by a large number of rolls, it was sequentially dried in a 120 ° C. drying zone and a 110 ° C. drying zone. After slitting the obtained film to a width of 1400 mm, a knurling process having a width of 15 mm and an average height of 10 μm was applied to both ends of the film to obtain an optical compensation film 1. The obtained optical compensation film 1 was wound on a core having an inner diameter of 6 inches with a winding initial tension of 220 N / m and a final tension of 110 N / m. The residual solvent amount of the optical compensation film 1 was 0.1%, the average film thickness was 80 μm, and the number of turns was 4000 m.

(Examples 1-2 to 1-7)
Optical compensation films 2 to 7 were obtained in the same manner as in Example 1-1 except that at least one of the type of cellulose ester, the type and amount of additives, and the stretching conditions were changed as shown in Table 2. In Examples 1-4 and 1-5, stretching in the web conveyance direction (MD direction) was performed after stretching in the web width direction (TD direction).

(Example 1-8)
A dope solution B was prepared in the same manner as in Example 1-1 except that the composition of the dope solution was changed as follows.
(Composition of dope solution B)
Cellulose ester 2 (cellulose acetate propionate, acetyl group substitution degree 1.58, propionyl group substitution degree 0.9, total acyl group substitution degree 2.48, Mn = 16000): 100 parts by mass Additive M2: 4 parts by mass Fine particle dispersion A: 4 parts by mass Methylene chloride: 390 parts by mass Ethanol: 80 parts by mass

  The obtained dope liquid B was uniformly cast on a stainless steel band support having a width of 2 m using a belt casting apparatus. The solvent contained in the cast film was evaporated on the stainless steel band support until the residual solvent amount became 110%, and then peeled from the stainless steel band support to obtain a web. The both ends of the obtained web are gripped with a tenter stretching machine and stretched at 160 ° C. and 1.40 times in the width direction of the web, and then held for 4 seconds while gripping both ends of the web. The tension in the width direction was relaxed. Thereafter, gripping at both ends of the web was released, and the web was transported and dried for 30 minutes in a drying zone set at 125 ° C. After slitting the obtained film to a width of 1.49 m, a knurling process having a width of 1 cm was applied to both ends of the film to obtain a base film. The substrate film had a R0 (550) of 50 nm and a Rth (550) of 250 nm at a measurement wavelength of 550 nm.

水：３７１質量部
メタノール：１１９質量部
グルタルアルデヒド：０．５質量部
化合物Ｂ：０．２質量部

After subjecting the surface of the obtained base film to alkali saponification, a coating solution for alignment film having the following composition was applied at 20 ml / m ² with a wire bar coater.
(Composition of coating solution for alignment film)
The following modified polyvinyl alcohol: 10 parts by mass

Water: 371 parts by mass Methanol: 119 parts by mass Glutaraldehyde: 0.5 parts by mass Compound B: 0.2 parts by mass

  The obtained coating film was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. The surface of the coating film obtained after drying was rubbed in a direction perpendicular to the slow axis direction of the base film to form an alignment film.

エチレンオキサイド変性トリメチロールプロパントリアクリレート（Ｖ＃３６０、大阪有機化学（株）製）：０．２ｇ
光重合開始剤（イルガキュアー９０７、チバガイギー社製）：０．０６ｇ
増感剤（カヤキュアーＤＥＴＸ、日本化薬（株）製）：０．０２ｇ
含フッ素ポリマー（下記の化合物Ａ）：０．０１ｇ

メチルエチルケトン：３．９ｇOn the obtained alignment film, the coating liquid for liquid crystal layers having the following composition was applied with a wire bar coater so that the thickness after curing was 1.4 μm.
(Composition of liquid crystal layer coating solution)
The following discotic liquid crystalline compound: 1.8 g

Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.): 0.2 g
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy): 0.06 g
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.): 0.02g
Fluorine-containing polymer (the following compound A): 0.01 g

Methyl ethyl ketone: 3.9 g

  The coating film of the liquid crystal layer coating solution was heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystalline compound in the coating film. Next, this coating film was irradiated with ultraviolet rays for 30 seconds using a 120 W / cm high-pressure mercury lamp to crosslink the discotic liquid crystalline compound to obtain a liquid crystal layer. The temperature of the coating film during UV curing was 80 ° C. Thereafter, the liquid crystal layer was allowed to cool to room temperature to obtain an optical compensation film 8 having a base film and a liquid crystal layer.

(Comparative Examples 1-1 to 1-4)
Optical compensation films 9 to 12 were obtained in the same manner as in Example 1-1 except that the stretching ratio, the stretching temperature, or the film thickness of the obtained film was changed as shown in Table 2.

(Comparative Example 1-5)
A dope solution C was prepared in the same manner as in Example 1-1 except that the composition of the dope solution was changed as follows.
(Composition of dope solution C)
Cellulose ester 2 (cellulose acetate propionate, acetyl group substitution degree 1.58, propionyl group substitution degree 0.90, total acyl group substitution degree 2.48, Mn = 16000): 100 parts by mass Glucose compound A-2 (added) Agent M1): 4 parts by mass Fine particle dispersion A: 4 parts by mass Methylene chloride: 390 parts by mass Ethanol: 80 parts by mass

  The obtained dope C was uniformly cast on a stainless steel band support having a width of 2 m using a belt casting apparatus. The solvent contained in the cast film was evaporated on the stainless steel band support until the residual solvent amount became 110%, and then peeled from the stainless steel band support to obtain a web. The both ends of the obtained web are gripped with a tenter stretching machine and stretched at 160 ° C. and 1.35 times in the width direction of the web, and then held for 4 seconds while gripping both ends of the web. The tension in the width direction was relaxed. Thereafter, gripping at both ends of the web was released, and the web was transported and dried for 30 minutes in a drying zone set at 125 ° C. After slitting the obtained film to a width of 1.49 m, a knurling process having a width of 1 cm was applied to both ends of the film to obtain an optical compensation film 13 having a length of 4000 m.

(Comparative Example 1-6)
Optical compensation film 14 was obtained in substantially the same manner as in Example 1-1 except that the type of cellulose ester, the type and amount of additives, and the stretching conditions were changed as shown in Table 2.

(Comparative Examples 1-7 to 1-8)
Optical compensation films 15 to 16 were obtained in substantially the same manner as in Example 1-1 except that the type of cellulose ester, the type and amount of additives, and the stretching conditions were changed as shown in Table 2. In Comparative Example 1-8, stretching in the web conveyance direction (MD direction) was performed after stretching in the web width direction (TD direction).

  The retardations R0 and Rth and wavelength dispersion characteristics (R0DSP, RthDSP) of the obtained optical compensation film were measured by the following methods.

Measurement of R0, Rth and wavelength dispersion characteristics (R0DSP, RthDSP) 1) The obtained optical compensation film was conditioned at 23 ° C. and 55% RH. The refractive index in three directions of the optical compensation film after humidity adjustment was measured with an Abbe refractometer, and the average value thereof was taken as the average refractive index.
2) R0 when light having a measurement wavelength of 450 nm, 550 nm, and 650 nm was incident on the optical compensation film after humidity adjustment from the normal direction of the film was measured with an Axoscan manufactured by Axometrics.
3) Retardation value R (θ) when Axoscan made by Axometrcs Inc. makes incident light having a measurement wavelength of 450 nm, 550 nm, and 650 nm from an angle θ (incident angle (θ)) with respect to the film normal direction, respectively. Was measured. θ is larger than 0 °, preferably 30 ° to 50 °.
4) From the measured R0 and R (θ) and the above-mentioned average refractive index and film thickness, nx, ny and nz were calculated by Axoscan made by Axomercs, and measured at wavelengths of 450 nm, 550 nm and 650 nm. Rth was calculated respectively. The retardation was measured under the conditions of 23 ° C. and 55% RH.

  R0 (450) / R0 (650) is calculated from the obtained R0 (450) and R0 (650); from the obtained Rth (450) and Rth (650), Rth (450) / Rth (650) Was calculated.

Table 2 shows the evaluation results of the optical compensation films of Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-8.

3. Production of Polarizing Plate Production of Polarizing Plate 1 A polyvinyl alcohol film having a thickness of 75 μm was swollen with water at 35 ° C. This film was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 45 ° C. composed of 3 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. . The film after immersion was uniaxially stretched at 55 ° C. and a stretch ratio of 5 times. The obtained film was washed with water and dried to obtain a polarizer.

  In addition to the obtained optical compensation film 1, a commercially available Konica Minolta Op KC4UA-SW was prepared as a transparent protective film. The optical compensation film 1 and the transparent protective film were each subjected to alkali saponification treatment using a 2N KOH aqueous solution at 50 ° C., washed with water and dried.

The saponified optical compensation film 1 is disposed on one surface of the polarizer via water glue; the saponified transparent protective film is disposed on the other surface of the polarizer via water glue. To obtain a laminate. The obtained laminate was bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 10 m / min, and then dried at 70 ° C. for about 2 minutes and then at 60 ° C. for about 2 minutes to obtain a polarizing plate 1. .

  On the other hand, an adhesive tape provided with an adhesive layer on a peeled polyethylene terephthalate film was prepared in advance. And the adhesive layer of the adhesive tape was affixed on the surface at the side of the optical compensation film of the obtained polarizing plate, and the polarizing plate 1 with an adhesive was obtained.

Preparation of Polarizing Plates 2 to 16 Polarizing plates 2 to 16 were obtained in the same manner as the polarizing plate 1 except that the optical compensation film 1 was changed to the optical compensation films 2 to 16, respectively. The optical compensation film 16 was bonded so that the base film was in contact with the polarizer.

Preparation of Polarizing Plate A Polarizing plate A was obtained in the same manner as polarizing plate 1 except that transparent protective film KC8UX was bonded to both sides of the polarizer instead of the optical compensation film and transparent protective film KC4UA-SW described above.

Preparation of polarizing plate B Polarizing plate B was prepared in the same manner as polarizing plate 1 except that transparent protective film KC4UA-SW was bonded to only one side of the polarizer instead of the optical compensation film and transparent protective film KC4UA-SW described above. Produced.

4). Production of liquid crystal display device (Example 2-1)
Production of Liquid Crystal Cell An ITO film was formed on a glass substrate by sputtering ITO through a mask having a predetermined pattern. A resist pattern was formed on the obtained ITO film, and the exposed portion of the ITO film was etched using this resist pattern as a mask to form the pixel electrode 26 as shown in FIG. Here, the width of the slit 24 provided in the pixel electrode 26 and the width of the pixel electrode 26 in the portion sandwiched between the two slits 24 and 24 are both 5 μm.

  A polyimide solution for alignment film was printed on the obtained pixel electrode to a thickness of 70 nm and then baked at 180 ° C. to form a vertical alignment film. Thereby, the substrate A was obtained.

  On the other hand, separately from the substrate A, a glass substrate with an ITO film was prepared. On this ITO film, a polyimide solution for alignment film was printed to a thickness of 70 nm and then baked at 180 ° C. to form a vertical alignment film. As a result, a substrate B disposed opposite to the substrate A was obtained.

  On the surface of the substrate A on which the vertical alignment film was formed, an adhesive containing spherical resin balls as a spacer was applied and formed in a frame shape. An opening for injecting the liquid crystal material was provided in the frame made of the adhesive. Next, the substrate A was bonded through a frame-shaped adhesive so that the surface of the substrate A on which the vertical alignment film was formed and the surface of the substrate B on which the vertical alignment film was formed were opposed to each other.

  The gap d of the liquid crystal cell was adjusted by the diameter of a spherical resin ball which is a spacer included in the adhesive. The diameter of the resin ball was selected so that the retardation Rth (cell) in the thickness direction of the liquid crystal cell had a target value, and the gap of the liquid crystal cell was 5.25 μm (d = 5250 nm).

  A liquid crystal material for display (Δn = 0.08, Δε = −4) having a negative dielectric anisotropy was injected into the obtained liquid crystal cell by a vacuum injection method. After injecting the liquid crystal material for display, the injection port was sealed with an ultraviolet curable resin to obtain a VA liquid crystal cell. Δnd of the obtained liquid crystal cell was 420 nm.

  A polarizing plate was bonded to both surfaces of the obtained liquid crystal cell as shown in Table 3 to obtain a liquid crystal display device.

(Examples 2-2 to 2-8, Comparative Examples 2-1 to 2-8)
A liquid crystal display device was obtained in the same manner as in Example 2-1, except that the polarizing plates to be bonded to both surfaces of the obtained liquid crystal cell were changed as shown in Table 3.

  The viewing angle and the diagonal color (color shift) of the obtained liquid crystal display device were evaluated by the following methods.

(Evaluation of viewing angle)
Measuring instrument (EZ-Contrast 160D, manufactured by ELDIM) in each of the azimuth angles 45 °, 135 °, 225 ° and 315 ° at a polar angle of 60 ° when the liquid crystal display device displays white. It measured using. Similarly, the luminance in each direction of polar angle 60 °, azimuth angle 45 °, 135 °, 225 °, or 315 ° when the liquid crystal display device displayed black was measured. The obtained luminance is applied to the following formula, and the contrast ratio in each of the azimuth angles 45 °, 135 °, 225 ° and 315 ° at the polar angle 60 ° is calculated, and the average value thereof is calculated. did.
Contrast ratio = (luminance in a certain direction when displaying white) / (luminance in a certain direction when displaying black) × 100
The polar angle refers to the angle in the rotation direction rising from the display screen, and the azimuth angle refers to the angle in the rotation direction within the plane of the display screen.

The viewing angle was evaluated based on the following criteria.
A: The average value of the contrast ratio is 60 or more. O: The average value of the contrast ratio is 40 or more and less than 60. X: The average value of the contrast ratio is 20 or more and less than 40.

(Evaluation of color in diagonal direction)
Using the EZ-Contrast 160D, the chromaticity coordinates (x, y) of the obtained liquid crystal display device in each direction of polar angle 60 °, azimuth angle 45 °, 135 °, 225 ° or 315 ° are measured. And the average value of them was calculated. The distance between the average value of the obtained chromaticity coordinates (x, y) and the chromaticity coordinates (0.313, 0.329) of the D65 light source was calculated by the formula (X).

The evaluation of the color in the oblique direction was performed based on the following criteria.
A: D ≦ 0.05
○: 0.05 <D ≦ 0.10
X: 0.10 <D

Table 3 shows the evaluation results of the liquid crystal display devices of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-8. In Table 3, the type of configuration of the liquid crystal display device is classified into one of I, II, and III; the configuration of I is shown in FIG. 3A, the configuration of II is shown in FIG. 3B, and the configuration of III is shown in FIG. 3A to 3C, as in FIG. 1, the upper side indicates the viewing side, and the lower side indicates the backlight side; the same members as those in FIG. P represents the absorption axis of the polarizer, and Q represents the slow axis of the optical compensation film or transparent protective film.

  In the liquid crystal display devices of Examples 2-1 to 2-8 having the optical compensation film of the present invention on at least one of the protective films F2 and F3, both the viewing angle and the color in the oblique direction are good. I understand. On the other hand, the liquid crystal display devices of Comparative Examples 2-1 to 2-8 that do not have the optical compensation film of the present invention on at least one of the protective films F2 and F3 have both a viewing angle and an oblique color. It turns out that it cannot raise simultaneously.

  This application claims priority based on Japanese Patent Application No. 2011-262165 filed on November 30, 2011. The contents described in the application specification and the drawings are all incorporated herein.

  INDUSTRIAL APPLICABILITY The present invention can provide an optical compensation film that is suitable for a vertical alignment type liquid crystal cell having a large Δnd and can improve contrast and color in an oblique direction and a liquid crystal display device including the same.

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 20 Liquid crystal cell 22 Board | substrate 22a, 22b, 22c, 22d Area | region 24 Slit 26 Pixel electrode 40 1st polarizing plate 42 1st polarizer 44 Protective film (F1)
46 Protective film (F2)
60 Second polarizing plate 62 Second polarizer 64 Protective film (F3)
66 Protection Film (F4)
80 Backlight

Claims (10)

An optical compensation film containing a cellulose ester,
The optical compensation film is at 23 ° C. and 55% RH.
Retardation in the in-plane direction defined by the following formula (I) and measured at a measurement wavelength of 450 nm, 550 nm, or 650 nm is R0 (450), R0 (550), or R0 (650), respectively.
When the retardation in the thickness direction defined by the following formula (II) and measured at a measurement wavelength of 450 nm, 550 nm or 650 nm is Rth (450), Rth (550) or Rth (650),
An optical compensation film that simultaneously satisfies the following formulas (1) to ( 5 ).
Formula (1) 0.7 <R0 (450) / R0 (650) <Rth (450) / Rth (650) <2
Formula (2) R0 (450) / R0 (650) <1.0
Formula (3) 40 nm <R0 (550) <80 nm
Formula (4) 100 nm <Rth (550) <260 nm
Formula (5) 1.0 ≦ Rth (450) / Rth (650)
Formula (I): R0 = (nx−ny) × t (nm)
Formula (II): Rth = {(nx + ny) / 2−nz} × t (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the optical compensation film;
ny represents the refractive index in the direction y orthogonal to the slow axis direction x in the in-plane direction of the optical compensation film;
nz represents the refractive index in the thickness direction z of the optical compensation film;
t (nm) represents the thickness of the optical compensation film)   The optical compensation film according to claim 1, wherein the cellulose ester has a total acyl group substitution degree of 1.5 to 3.0 and an acetyl group substitution degree of 2.5 or less. The optical compensation film according to claim 1 or 2 , comprising one or more selected from the group consisting of a compound represented by the general formula (1A), a sugar ester compound, a phosphate ester plasticizer, and a glycolate plasticizer.

(In the general formula (1A),
L ¹ and L ² each independently represent a single bond or a divalent linking group represented by the following formula;

A ¹ and A ² each independently represent —O—, —NR— (R represents a hydrogen atom or a substituent), —S— or —CO—;
R ^{1 to} R ⁵ each independently represents a substituent;
n represents an integer of 0 to 2) The optical compensation film according to claim 3, wherein the sugar ester compound is a compound represented by the following formula (6).

(R _{1 to} R _{8 in} the general formula (6) represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group; R _{1 to} R ₈ may be the same or different from each other. May be)   Content of the compound represented by the said general formula (1A) is an optical compensation film of Claim 3 which is 0.1-30 mass% with respect to the said cellulose ester.   4. The optical compensation film according to claim 3, wherein the content of the sugar ester compound is 1 to 40 mass% with respect to the cellulose ester. The thickness of the said optical compensation film is an optical compensation film as described in any one of Claims 1-6 which is 25-100 micrometers. A polarizer,
The optical compensation film according to any one of claims 1 to 7 disposed on at least one surface of the polarizer,
The polarizing plate in which the absorption axis of the polarizer and the slow axis of the optical compensation film are orthogonal. A liquid crystal display device having, in order, a first polarizing plate having a first polarizer, a liquid crystal cell, and a second polarizing plate having a second polarizer,
The liquid crystal cell includes a pair of opposing substrates and a liquid crystal layer sandwiched between the pair of substrates and containing liquid crystal,
The liquid crystal cell is configured such that when no voltage is applied, the liquid crystal is oriented perpendicular to the pair of substrate surfaces, and when a voltage is applied, the liquid crystal is oriented in a direction parallel to the pair of substrate surfaces, And when the gap of the liquid crystal cell is d (nm) and the refractive index anisotropy of the liquid crystal at 23 ° C. and a measurement wavelength of 550 nm is Δn, 320 nm <Δnd <470 nm is satisfied,
Whether the first polarizing plate has the optical compensation film according to any one of claims 1 to 7 disposed on a liquid crystal cell side surface of the first polarizer,
The second polarizing plate has the optical compensation film according to any one of claims 1 to 7 disposed on a liquid crystal cell side surface of the second polarizer, or
The first polarizing plate has the optical compensation film according to any one of claims 1 to 7, which is disposed on a liquid crystal cell side surface of the first polarizer, and the second polarized light. The liquid crystal display device which has an optical compensation film as described in any one of Claims 1-7 by which the board is arrange | positioned at the surface at the side of the liquid crystal cell of said 2nd polarizer . The first polarizing plate has the optical compensation film disposed on the liquid crystal cell side surface of the first polarizer, and the second polarizing plate is a liquid crystal cell of the second polarizer. The liquid crystal display device according to claim 9 , comprising the optical compensation film disposed on a side surface .

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