JP2007298916A - Retardation film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress humidity-dependent variation of retardation value which is the defect of the conventional cellulose-based retardation film, and to provide a retardation film giving stable display quality, a polarizing plate, and a liquid crystal display device. <P>SOLUTION: The retardation film contains an amylose ester. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  A phase difference film is used to increase the viewing angle or improve the contrast of the liquid crystal display device.

  The retardation film has a specific retardation value (retardation value). When this value changes, the viewing angle and color tone particularly when viewed from an oblique direction change (deteriorate). Various materials are used for the retardation film in order to realize various configurations, and these materials may change reversibly in response to changes in the environment (particularly the humidity environment). In the case of a retardation film in which a layer (an optically anisotropic layer) that generates another retardation is laminated on a support film, for example, a TAC film is used as a support on which a liquid crystal layer is applied. However, this TAC film itself has a retardation value (particularly, retardation in the thickness direction), and the retardation value varies depending on moisture adsorption / desorption. In particular, moisture adsorption / desorption depends on the hydroxyl group of the cellulose ester, and moisture adsorption / desorption becomes more severe as the total degree of substitution is lower.

In addition, recently, the present inventors have developed a retardation by stretching a cellulose derivative film instead of a conventional TAC film, and saponifying this and laminating a PVA polarizer so as to have a retardation film function. A protective film was realized (see, for example, Patent Document 1). However, this film has a smaller variation in retardation value due to a variation in humidity than a normal TAC film, but further improvement is required.
JP 2003-270442 A

  An object of the present invention is to provide a retardation film, a polarizing plate, and a liquid crystal display device, in which the humidity fluctuation of the retardation value, which is a drawback of the conventional cellulose-based retardation film, is suppressed and the display quality is stable.

  The above object of the present invention is achieved by the following configurations.

  1. A retardation film comprising amylose ester.

  2. 2. The retardation film as described in 1 above, wherein the amylose ester has a total acyl group substitution degree of 2.0 to 3.0.

  3. The retardation film as described in 1 or 2 above, wherein Ro is 20 to 80 nm and Rt is 100 to 250 nm at a wavelength of 590 nm under 23.degree. C. and 55% RH. .

Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is Film thickness (nm).)
4). A polarizing plate comprising the retardation film according to any one of 1 to 3 on at least one surface of a polarizer.

  5. A liquid crystal display device comprising the retardation film according to any one of 1 to 3 above.

  6). 6. The liquid crystal display device as described in 5 above, wherein the liquid crystal cell is a VA liquid crystal cell.

  According to the present invention, it is possible to provide a retardation film, a polarizing plate, and a liquid crystal display device with stable display quality by suppressing the humidity fluctuation of the retardation value, which is a drawback of the conventional cellulose-based retardation film.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  As a result of intensive studies in view of the above problems, the inventors of the present invention have a retardation film characterized by containing an amylose ester. It has been found that a polarizing plate and a liquid crystal display device can be obtained, and the present invention has been made.

  In the present invention, the reversible fluctuation is a measurement result under the same conditions at the first and last humidity changes, and can be regarded as a reversible fluctuation if the fluctuation is within the standard range of the measuring instrument. In the present invention, the reversible fluctuation of the retardation value is It is defined that the change is observed when the film is conditioned for 5 hours and brought into equilibrium with the environment.

  In order to confirm the improvement effect of the reversible fluctuation in the present invention, it is preferable to measure the phase difference or the viewing angle by changing the humidity while keeping the temperature constant. In addition, before and after measurement under humidity change conditions, normal environment (for example, 23 ° C., 55% RH, etc.) can be measured to confirm reversible fluctuation.

  The retardation value can be measured using an automatic birefringence measuring apparatus (trade name KOBRA-21ADH manufactured by Oji Scientific Instruments).

  Hereinafter, each element of the present invention will be described in detail.

[Amylose]
Examples of the amylose used as a raw material for the amylose ester used in the present invention include those contained in natural starch and those synthesized by enzymatic synthesis, but those synthesized by enzymatic synthesis are preferred. There are several known methods for synthesizing amylose using an enzyme, such as a starch enzymatic degradation method and a method using amylosucrase, but a method using phosphorylase is particularly preferred.

  Phosphorylase is an enzyme that catalyzes the phosphorolysis reaction, and there are several methods using phosphorylase. For example, glucan phosphorylase (α-glucan phosphorylase, EC 2.4.1.1; usually referred to as phosphorylase) is allowed to act on the glucose-1-phosphate glucosyl group as a primer to maltoheptaose as a primer. There are a transfer method, a method in which sucrose is used as a substrate and malto-oligosaccharide is used as a primer, and sucrose phosphorylase and glucan phosphorylase are simultaneously reacted in the presence of inorganic phosphate to synthesize amylose.

[Amylose ester]
As a method for synthesizing amylose ester used in the present invention, amylose is generally reacted with acid anhydride, organic acid, acid chloride, ketene or other esterification reagent in various solvents. Representative synthesis methods are listed below, but are not limited thereto.

  Specifically, amylose is dissolved in dimethyl sulfoxide and esterified by adding sodium carbonate and vinyl acetate or acetic anhydride. After the reaction, water can be added to the amylose ester solution to separate the amylose ester, and the amylose ester can be obtained by washing. By changing the ratio of sodium carbonate and vinyl acetate or acetic anhydride, amylose esters with various degrees of substitution can be obtained.

  The degree of substitution was calculated from the mass difference before and after the reaction.

  The amylose ester used in the present invention has an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y, the following formula ( Amylose esters that simultaneously satisfy I) and (II) are preferred.

Formula (I) 2.0 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 3.0
Among them, amylose ester (total acyl group substitution degree = X + Y) of 1.0 ≦ X ≦ 2.0 and 0 ≦ Y ≦ 1.0 is preferable.

  The degree of substitution of these acyl groups can be measured according to the method prescribed in ASTM-D817-96.

  The molecular weight of the amylose ester is preferably 10,000 to 1,000,000, more preferably 60000 to 1,000,000 in terms of weight average molecular weight (Mn). Moreover, it is preferable that Mw / Mn ratio is 1.25 or less, More preferably, it is 1.15 or less.

  Since the weight average molecular weight Mw and the number average molecular weight Mn of amylose ester can be measured using gel permeation chromatography, the number average molecular weight (Mn), the weight average molecular weight (Mw), and the Mw / Mn ratio are calculated using this. can do.

  Moreover, amylose ester can also be used individually or in combination with a cellulose ester.

  Cellulose esters that can be used in combination include triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, cellulose acetate trimelli Examples thereof include cellulose esters such as tate and cellulose nitrate.

  The cellulose as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, although the cellulose derivative obtained from these can be used individually or in mixture in arbitrary ratios, it is preferable to use 50 mass% or more of cotton linters.

  When the molecular weight of the cellulose ester is large, the elastic modulus is increased. However, when the molecular weight is excessively increased, the viscosity of the cellulose ester solution becomes too high, and the productivity is lowered. The molecular weight of the cellulose ester is preferably 30000-200000 in terms of number average molecular weight (Mn). The cellulose ester preferably has a Mw / Mn ratio of 4.0 or less, more preferably 1.4 to 2.3.

  Since the average molecular weight and molecular weight distribution of the cellulose ester can be measured using high performance liquid chromatography, the number average molecular weight (Mn) and the mass average molecular weight (Mw) can be calculated using this, and the ratio can be calculated.

  A preferred cellulose ester has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and the substitution degree of propionyl group or butyryl group is Y, and the following formula (I) and It is a cellulose ester that simultaneously satisfies (II).

Formula (I) 2.0 ≦ X + Y ≦ 2.6
Formula (II) 0 ≦ X ≦ 2.6
Cellulose acetate propionate (total acyl group substitution degree = X + Y) of 2.4 ≦ X + Y ≦ 2.7, 1.4 ≦ X ≦ 2.3, and 0.1 ≦ Y ≦ 1.3 is preferable. The degree of substitution of these acyl groups can be measured according to the method prescribed in ASTM-D817-96. The portion not substituted with an acyl group usually exists as a hydroxyl group. These cellulose esters can be synthesized by a known method. Further, cellulose acylate having an acyl group and a carbamoyl group can also be preferably used. Specifically, the cellulose acylate described in JP-A-2005-68314 [0014] to [0029] and the cellulose acylate described in JP-A-2004-315613 [0045] to [0052] are used in the present invention. Are preferably used.

  The mixing ratio of amylose ester and cellulose ester in the film is preferably 100: 0 to 5:95, more preferably 100: 0 to 50:50.

〔solvent〕
The amylose ester according to the present invention is dissolved in a solvent to form a dope, which is cast on a substrate to form a film. At this time, since it is necessary to evaporate the solvent after extrusion or casting, it is preferable to use a volatile solvent. Furthermore, the casting substrate is not dissolved. Two or more solvents may be mixed and used.

  Here, an organic solvent having good solubility in the amylose ester is referred to as a good solvent, and has a main effect on dissolution, and an organic solvent used in a large amount among them is a main (organic) solvent or a main (organic) ) Solvent.

  Examples of good solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, and the like. In addition to esters such as methyl acid, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethylsulfoxide, sulfolane, nitroethane, methylene chloride 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferable.

  The dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. After casting the dope on the metal support, the solvent starts to evaporate and the alcohol ratio increases, so that the web (the name of the dope film after casting the dope of amylose ester on the support is referred to as the web). )), And it is used as a gelling solvent to make the web strong and easy to peel off from the metal support. When these ratios are small, it promotes dissolution of amylose ester of non-chlorine organic solvent. There is also a role to do.

  Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, and propylene glycol monomethyl ether. Of these, ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity. These organic solvents alone are not soluble in amylose esters and are referred to as poor solvents.

  The most preferable solvent that satisfies such conditions and dissolves amylose ester, which is a preferred polymer compound, at a high concentration is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20. Alternatively, a mixed solvent of methyl acetate: ethyl alcohol 60:40 to 95: 5 is also preferably used.

〔Additive〕
The retardation film of the present invention includes a plasticizer that imparts processability, flexibility, and moisture resistance to the film, an ultraviolet absorber that imparts an ultraviolet absorbing function, an antioxidant that prevents deterioration of the film, and slipperiness to the film. Fine particles to be imparted (matting agent), a retardation adjusting agent for adjusting the retardation of the film, and the like may be contained.

(Plasticizer)
The plasticizer is not particularly limited, but preferably has a functional group capable of interacting with an amylose ester by hydrogen bonding or the like so as not to cause haze in the film, bleed out or volatilize from the film.

  Examples of such functional groups include hydroxyl groups, ether groups, carbonyl groups, ester groups, carboxylic acid residues, amino groups, imino groups, amide groups, imide groups, cyano groups, nitro groups, sulfonyl groups, sulfonic acid residues, Examples thereof include a phosphonyl group and a phosphonic acid residue, and a carbonyl group, an ester group and a phosphonyl group are preferred.

  Examples of such plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers, glycolate plasticizers. Citric acid ester plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, and the like can be preferably used. Particularly, in order to obtain the effects of the present invention, polyhydric alcohols are preferable. It is to use a plasticizer and an ester plasticizer, and it is particularly preferable to contain a polyhydric alcohol ester plasticizer and an aromatic terminal ester plasticizer described later.

(Polyhydric ester plasticizer)
The polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  The polyhydric alcohol used in the present invention is represented by the following general formula (1).

Formula (1) R _1- (OH) _n
(In the formula, R ₁ represents an n-valent organic group, and n represents a positive integer of 2 or more.)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. 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- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, pentaerythritol, dipentaerythritol and the like.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. Among these, it is preferable to use acetic acid, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as 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, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferable because it is less likely to volatilize, and a lower molecular weight is preferable in terms of moisture permeability and compatibility with amylose ester. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The specific compound of a polyhydric alcohol ester is shown below.

  The content of the polyhydric alcohol ester plasticizer is preferably 1 to 15% by mass, particularly preferably 3 to 10% by mass in the amylose ester film.

(Ester plasticizer)
The ester plasticizer is not particularly limited, but an ester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be preferably used. Although it does not specifically limit as a preferable ester plasticizer, For example, the aromatic terminal ester plasticizer represented by following General formula (2) is preferable.

General formula (2) B- (GA) _n -GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
A benzene monocarboxylic acid residue represented by B of an ester plasticizer, an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue represented by G, and an alkylene dicarboxylic acid residue represented by A Or it is comprised from an aryl dicarboxylic acid residue, and is obtained by reaction similar to a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the ester plasticizer used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl benzoic acid. There are acid, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the ester plasticizer used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3 -Methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, -Ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Or it is used as a mixture of two or more. In particular, alkylene glycols having 2 to 12 carbon atoms are particularly preferable because of excellent compatibility with amylose esters.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Or it can be used as a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The ester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is preferably 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Hereinafter, synthesis examples of aromatic terminal ester plasticizers preferably used in the present invention will be shown.

<Sample No. 1 (Aromatic terminal ester sample)>
A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While refluxing the monohydric alcohol, heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Subsequently, the distillate was removed at 200 to 230 ° C. under a reduced pressure of 100 to finally 4 × 10 ² Pa or less, and then filtered to obtain an aromatic terminal ester plasticizer having the following properties.

Viscosity (25 ° C., mPa · s); 43400
Acid value: 0.2
<Sample No. 2 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in Example 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 31000
Acid value: 0.1
<Sample No. 3 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in Example 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 38000
Acid value: 0.05
<Sample No. 4 (Aromatic terminal ester sample)>
Sample No. 4 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in Example 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 37000
Acid value: 0.05
Although the specific compound of the aromatic terminal ester plasticizer which concerns on this invention below is shown, this invention is not limited to this.

(Other plasticizers)
The polyvalent carboxylic acid plasticizer useful in the present invention comprises a divalent or higher, preferably 2-20 valent polyvalent carboxylic acid and an alcohol ester. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid used in the present invention is represented by the following general formula (Y).

Formula (Y) R ₅ (COOH) _m (OH) _n
(However, R ₅ is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group.)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. 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, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving the retention.

  There is no restriction | limiting in particular as alcohol used for a polyhydric carboxylic acid ester compound, Well-known alcohol and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as 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, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  Although there is no restriction | limiting in particular in the molecular weight of a polyhydric carboxylic acid ester compound, It is preferable that it is the range of molecular weight 300-1000, and it is more preferable that it is the range of 350-750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with amylose ester.

  The alcohol used for the polyvalent carboxylic acid ester used in the present invention may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

  These plasticizers can be used alone or in combination of two or more. If the amount of the plasticizer used is less than 1% by mass relative to the amylose ester, it is not preferable because the effect of reducing the moisture permeability of the film is small. If it exceeds 20% by mass, the plasticizer bleeds out from the film, and the physical properties of the film are poor. Since it deteriorates, 1-20 mass% is preferable. 6-16 mass% is further more preferable, Most preferably, it is 8-13 mass%.

(UV absorber)
The ultraviolet absorbing function is preferably imparted to various optical films such as a polarizing plate protective film, a retardation film, and an optical compensation film from the viewpoint of preventing deterioration of the liquid crystal. For such an ultraviolet absorbing function, a material that absorbs ultraviolet rays may be contained in amylose ester, or a layer having an ultraviolet absorbing function may be provided on a film made of amylose ester.

  As such an ultraviolet absorber having an ultraviolet absorbing function, those having an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less and little absorption of visible light having a wavelength of 400 nm or more are preferably used. Specific examples of preferably used ultraviolet absorbers include triazine compounds, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, it is not limited to these. Moreover, the polymeric ultraviolet absorber described in JP-A-6-148430 is also preferably used.

  Specific examples of ultraviolet absorbers useful in the present invention include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl). -Phenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butyl) -Phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methyl-phenyl) benzotriazole, 2 , 2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy -3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methyl-phenol [TINUVIN 171], 2-octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [ A mixture of 3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate [TINUVIN 109], 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol [tinuvin 234], 2- (3- - butyl-5-methyl-2-hydroxyphenyl) -5-chloro - it can be exemplified benzotriazole [Tinuvin (TINUVIN) 326], and the like. In addition, any of the above-mentioned tinuvins such as tinuvin 109, tinuvin 171 and tinuvin 326 are commercially available products manufactured by Ciba Specialty Chemicals and can be preferably used.

  Specific examples of benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but is not limited thereto.

  Moreover, since the ultraviolet absorber which can be used for the retardation film of this invention is excellent also in the applicability | paintability of various coating layers, the ultraviolet absorption whose distribution coefficient described in Unexamined-Japanese-Patent No. 2000-187825 is 9.2 or more. It is preferable to use an ultraviolet absorber having a partition coefficient of 10.1 or more.

  Moreover, the polymeric ultraviolet absorber (or ultraviolet absorbing polymer) described in JP-A-6-148430 and JP-A-2002-47357 can be preferably used. The polymer ultraviolet absorbers described in general formula (1) or general formula (2) of JP-A-6-148430 or general formulas (3), (6), and (7) of JP-A-2002-47357 are particularly preferable. Used.

  In addition, a compound having a 1,3,5-triazine ring can be preferably used as the ultraviolet absorber of the retardation film of the present invention. The compound can also be used as a retardation adjusting agent.

  Specific examples of the compound having a 1,3,5-triazine ring are shown below.

  In addition, several R shown below represents the same group.

(1) Butyl (2) 2-Methoxy-2-ethoxyethyl (3) 5-Undecenyl (4) Phenyl (5) 4-Ethoxycarbonylphenyl (6) 4-Butoxyphenyl (7) p-Biphenylyl (8) 4 -Pyridyl (9) 2-naphthyl (10) 2-methylphenyl (11) 3,4-dimethoxyphenyl (12) 2-furyl

(14) phenyl (15) 3-ethoxycarbonylphenyl (16) 3-butoxyphenyl (17) m-biphenylyl (18) 3-phenylthiophenyl (19) 3-chlorophenyl (20) 3-benzoylphenyl (21) 3 -Acetoxyphenyl (22) 3-benzoyloxyphenyl (23) 3-phenoxycarbonylphenyl (24) 3-methoxyphenyl (25) 3-anilinophenyl (26) 3-isobutyrylaminophenyl (27) 3-phenoxy Carbonylaminophenyl (28) 3- (3-ethylureido) phenyl (29) 3- (3,3-diethylureido) phenyl (30) 3-methylphenyl (31) 3-phenoxyphenyl (32) 3-hydroxyphenyl (33) 4-Ethoxycarbonylphenyl (34) 4-butoxyphenyl (35) p-biphenylyl (36) 4-phenylthiophenyl (37) 4-chlorophenyl (38) 4-benzoylphenyl (39) 4-acetoxyphenyl (40) 4-benzoyloxyphenyl ( 41) 4-phenoxycarbonylphenyl (42) 4-methoxyphenyl (43) 4-anilinophenyl (44) 4-isobutyrylaminophenyl (45) 4-phenoxycarbonylaminophenyl (46) 4- (3-ethyl (Ureido) phenyl (47) 4- (3,3-diethylureido) phenyl (48) 4-methylphenyl (49) 4-phenoxyphenyl (50) 4-hydroxyphenyl (51) 3,4-diethoxycarbonylphenyl ( 52) 3,4-dibutoxyphenyl (53) 3 -Diphenylphenyl (54) 3,4-diphenylthiophenyl (55) 3,4-dichlorophenyl (56) 3,4-dibenzoylphenyl (57) 3,4-diacetoxyphenyl (58) 3,4-dibenzoyl Oxyphenyl (59) 3,4-diphenoxycarbonylphenyl (60) 3,4-dimethoxyphenyl (61) 3,4-dianilinophenyl (62) 3,4-dimethylphenyl (63) 3,4-diphenoxy Phenyl (64) 3,4-dihydroxyphenyl (65) 2-naphthyl (66) 3,4,5-triethoxycarbonylphenyl (67) 3,4,5-tributoxyphenyl (68) 3,4,5- Triphenylphenyl (69) 3,4,5-triphenylthiophenyl (70) 3,4,5-trichlorophenyl (71) 3,4,5-tribenzoylphenyl (72) 3,4,5-triacetoxyphenyl (73) 3,4,5-tribenzoyloxyphenyl (74) 3,4,5-triphenoxycarbonylphenyl (75) 3,4,5-trimethoxyphenyl (76) 3,4,5-trianilinophenyl (77) 3,4,5-trimethylphenyl (78) 3,4,5-triphenoxyphenyl (79 ) 3,4,5-trihydroxyphenyl

(80) phenyl (81) 3-ethoxycarbonylphenyl (82) 3-butoxyphenyl (83) m-biphenylyl (84) 3-phenylthiophenyl (85) 3-chlorophenyl (86) 3-benzoylphenyl (87) 3 -Acetoxyphenyl (88) 3-benzoyloxyphenyl (89) 3-phenoxycarbonylphenyl (90) 3-methoxyphenyl (91) 3-anilinophenyl (92) 3-isobutyrylaminophenyl (93) 3-phenoxy Carbonylaminophenyl (94) 3- (3-ethylureido) phenyl (95) 3- (3,3-diethylureido) phenyl (96) 3-methylphenyl (97) 3-phenoxyphenyl (98) 3-hydroxyphenyl (99) 4-Ethoxycarbonylphenyl (100) 4-butoxyphenyl (101) p-biphenylyl (102) 4-phenylthiophenyl (103) 4-chlorophenyl (104) 4-benzoylphenyl (105) 4-acetoxyphenyl (106) 4-benzoyloxyphenyl ( 107) 4-phenoxycarbonylphenyl (108) 4-methoxyphenyl (109) 4-anilinophenyl (110) 4-isobutyrylaminophenyl (111) 4-phenoxycarbonylaminophenyl (112) 4- (3-ethyl (Ureido) phenyl (113) 4- (3,3-diethylureido) phenyl (114) 4-methylphenyl (115) 4-phenoxyphenyl (116) 4-hydroxyphenyl (117) 3,4-diethoxycarbonylphenyl ( 118) 3 , 4-dibutoxyphenyl (119) 3,4-diphenylphenyl (120) 3,4-diphenylthiophenyl (121) 3,4-dichlorophenyl (122) 3,4-dibenzoylphenyl (123) 3,4- Diacetoxyphenyl (124) 3,4-dibenzoyloxyphenyl (125) 3,4-diphenoxycarbonylphenyl (126) 3,4-dimethoxyphenyl (127) 3,4-dianilinophenyl (128) 3,4 -Dimethylphenyl (129) 3,4-diphenoxyphenyl (130) 3,4-dihydroxyphenyl (131) 2-naphthyl (132) 3,4,5-triethoxycarbonylphenyl (133) 3,4,5- Tributoxyphenyl (134) 3,4,5-triphenylphenyl (135) 3 4,5-triphenylthiophenyl (136) 3,4,5-trichlorophenyl (137) 3,4,5-tribenzoylphenyl (138) 3,4,5-triacetoxyphenyl (139) 3,4 5-tribenzoyloxyphenyl (140) 3,4,5-triphenoxycarbonylphenyl (141) 3,4,5-trimethoxyphenyl (142) 3,4,5-trianilinophenyl (143) 3,4 , 5-trimethylphenyl (144) 3,4,5-triphenoxyphenyl (145) 3,4,5-trihydroxyphenyl

(146) phenyl (147) 4-ethoxycarbonylphenyl (148) 4-butoxyphenyl (149) p-biphenylyl (150) 4-phenylthiophenyl (151) 4-chlorophenyl (152) 4-benzoylphenyl (153) 4 -Acetoxyphenyl (154) 4-benzoyloxyphenyl (155) 4-phenoxycarbonylphenyl (156) 4-methoxyphenyl (157) 4-anilinophenyl (158) 4-isobutyrylaminophenyl (159) 4-phenoxy Carbonylaminophenyl (160) 4- (3-ethylureido) phenyl (161) 4- (3,3-diethylureido) phenyl (162) 4-methylphenyl (163) 4-phenoxyphenyl (164) 4-hydroxyphenyl

(165) phenyl (166) 4-ethoxycarbonylphenyl (167) 4-butoxyphenyl (168) p-biphenylyl (169) 4-phenylthiophenyl (170) 4-chlorophenyl (171) 4-benzoylphenyl (172) 4 -Acetoxyphenyl (173) 4-benzoyloxyphenyl (174) 4-phenoxycarbonylphenyl (175) 4-methoxyphenyl (176) 4-anilinophenyl (177) 4-isobutyrylaminophenyl (178) 4-phenoxy Carbonylaminophenyl (179) 4- (3-ethylureido) phenyl (180) 4- (3,3-diethylureido) phenyl (181) 4-methylphenyl (182) 4-phenoxyphenyl (183) 4-hydroxyphenyl

(184) phenyl (185) 4-ethoxycarbonylphenyl (186) 4-butoxyphenyl (187) p-biphenylyl (188) 4-phenylthiophenyl (189) 4-chlorophenyl (190) 4-benzoylphenyl (191) 4 -Acetoxyphenyl (192) 4-benzoyloxyphenyl (193) 4-phenoxycarbonylphenyl (194) 4-methoxyphenyl (195) 4-anilinophenyl (196) 4-isobutyrylaminophenyl (197) 4-phenoxy Carbonylaminophenyl (198) 4- (3-ethylureido) phenyl (199) 4- (3,3-diethylureido) phenyl (200) 4-methylphenyl (201) 4-phenoxyphenyl (202) 4-hydroxyphenyl

(203) phenyl (204) 4-ethoxycarbonylphenyl (205) 4-butoxyphenyl (206) p-biphenylyl (207) 4-phenylthiophenyl (208) 4-chlorophenyl (209) 4-benzoylphenyl (210) 4 -Acetoxyphenyl (211) 4-benzoyloxyphenyl (212) 4-phenoxycarbonylphenyl (213) 4-methoxyphenyl (214) 4-anilinophenyl (215) 4-isobutyrylaminophenyl (216) 4-phenoxy Carbonylaminophenyl (217) 4- (3-ethylureido) phenyl (218) 4- (3,3-diethylureido) phenyl (219) 4-methylphenyl (220) 4-phenoxyphenyl (221) 4-hydroxyphenyl

(222) phenyl (223) 4-butylphenyl (224) 4- (2-methoxy-2-ethoxyethyl) phenyl (225) 4- (5-nonenyl) phenyl (226) p-biphenylyl (227) 4-ethoxy Carbonylphenyl (228) 4-butoxyphenyl (229) 4-methylphenyl (230) 4-chlorophenyl (231) 4-phenylthiophenyl (232) 4-benzoylphenyl (233) 4-acetoxyphenyl (234) 4-benzoyl Oxyphenyl (235) 4-phenoxycarbonylphenyl (236) 4-methoxyphenyl (237) 4-anilinophenyl (238) 4-isobutyrylaminophenyl (239) 4-phenoxycarbonylaminophenyl (240) 4- ( 3-ethylureido Phenyl (241) 4- (3,3-diethylureido) phenyl (242) 4-phenoxyphenyl (243) 4-hydroxyphenyl (244) 3-butylphenyl (245) 3- (2-methoxy-2-ethoxyethyl) ) Phenyl (246) 3- (5-nonenyl) phenyl (247) m-biphenylyl (248) 3-ethoxycarbonylphenyl (249) 3-butoxyphenyl (250) 3-methylphenyl (251) 3-chlorophenyl (252) 3-phenylthiophenyl (253) 3-benzoylphenyl (254) 3-acetoxyphenyl (255) 3-benzoyloxyphenyl (256) 3-phenoxycarbonylphenyl (257) 3-methoxyphenyl (258) 3-anilinophenyl (259) 3-I Butyrylaminophenyl (260) 3-phenoxycarbonylaminophenyl (261) 3- (3-ethylureido) phenyl (262) 3- (3,3-diethylureido) phenyl (263) 3-phenoxyphenyl (264) 3 -Hydroxyphenyl (265) 2-butylphenyl (266) 2- (2-methoxy-2-ethoxyethyl) phenyl (267) 2- (5-nonenyl) phenyl (268) o-biphenylyl (269) 2-ethoxycarbonyl Phenyl (270) 2-Butoxyphenyl (271) 2-Methylphenyl (272) 2-Chlorophenyl (273) 2-Phenylthiophenyl (274) 2-Benzoylphenyl (275) 2-Acetoxyphenyl (276) 2-Benzoyloxy Phenyl (277) 2 Phenoxycarbonylphenyl (278) 2-methoxyphenyl (279) 2-anilinophenyl (280) 2-isobutyrylaminophenyl (281) 2-phenoxycarbonylaminophenyl (282) 2- (3-ethylureido) phenyl ( 283) 2- (3,3-diethylureido) phenyl (284) 2-phenoxyphenyl (285) 2-hydroxyphenyl (286) 3,4-dibutylphenyl (287) 3,4-di (2-methoxy-2) -Ethoxyethyl) phenyl (288) 3,4-diphenylphenyl (289) 3,4-diethoxycarbonylphenyl (290) 3,4-didodecyloxyphenyl (291) 3,4-dimethylphenyl (292) 3, 4-dichlorophenyl (293) 3,4-dibenzoyl Enyl (294) 3,4-diacetoxyphenyl (295) 3,4-dimethoxyphenyl (296) 3,4-di-N-methylaminophenyl (297) 3,4-diisobutyrylaminophenyl (298) 3 , 4-diphenoxyphenyl (299) 3,4-dihydroxyphenyl (300) 3,5-dibutylphenyl (301) 3,5-di (2-methoxy-2-ethoxyethyl) phenyl (302) 3,5- Diphenylphenyl (303) 3,5-diethoxycarbonylphenyl (304) 3,5-didodecyloxyphenyl (305) 3,5-dimethylphenyl (306) 3,5-dichlorophenyl (307) 3,5-dibenzoyl Phenyl (308) 3,5-diacetoxyphenyl (309) 3,5-dimethoxyphenyl (3 0) 3,5-di-N-methylaminophenyl (311) 3,5-diisobutyrylaminophenyl (312) 3,5-diphenoxyphenyl (313) 3,5-dihydroxyphenyl (314) 2,4 -Dibutylphenyl (315) 2,4-di (2-methoxy-2-ethoxyethyl) phenyl (316) 2,4-diphenylphenyl (317) 2,4-diethoxycarbonylphenyl (318) 2,4-di Dodecyloxyphenyl (319) 2,4-dimethylphenyl (320) 2,4-dichlorophenyl (321) 2,4-dibenzoylphenyl (322) 2,4-diacetoxyphenyl (323) 2,4-dimethoxyphenyl ( 324) 2,4-di-N-methylaminophenyl (325) 2,4-diisobutyrylaminopheny (326) 2,4-diphenoxyphenyl (327) 2,4-dihydroxyphenyl (328) 2,3-dibutylphenyl (329) 2,3-di (2-methoxy-2-ethoxyethyl) phenyl (330) 2,3-diphenylphenyl (331) 2,3-diethoxycarbonylphenyl (332) 2,3-didodecyloxyphenyl (333) 2,3-dimethylphenyl (334) 2,3-dichlorophenyl (335) 2, 3-dibenzoylphenyl (336) 2,3-diacetoxyphenyl (337) 2,3-dimethoxyphenyl (338) 2,3-di-N-methylaminophenyl (339) 2,3-diisobutyrylaminophenyl (340) 2,3-diphenoxyphenyl (341) 2,3-dihydroxyphenyl (342 2,6-dibutylphenyl (343) 2,6-di (2-methoxy-2-ethoxyethyl) phenyl (344) 2,6-diphenylphenyl (345) 2,6-diethoxycarbonylphenyl (346) 2, 6-didodecyloxyphenyl (347) 2,6-dimethylphenyl (348) 2,6-dichlorophenyl (349) 2,6-dibenzoylphenyl (350) 2,6-diacetoxyphenyl (351) 2,6- Dimethoxyphenyl (352) 2,6-di-N-methylaminophenyl (353) 2,6-diisobutyrylaminophenyl (354) 2,6-diphenoxyphenyl (355) 2,6-dihydroxyphenyl (356) 3,4,5-tributylphenyl (357) 3,4,5-tri (2-methoxy-2-ethoxy) Til) phenyl (358) 3,4,5-triphenylphenyl (359) 3,4,5-triethoxycarbonylphenyl (360) 3,4,5-tridodecyloxyphenyl (361) 3,4,5- Trimethylphenyl (362) 3,4,5-trichlorophenyl (363) 3,4,5-tribenzoylphenyl (364) 3,4,5-triacetoxyphenyl (365) 3,4,5-trimethoxyphenyl ( 366) 3,4,5-tri-N-methylaminophenyl (367) 3,4,5-triisobutyrylaminophenyl (368) 3,4,5-triphenoxyphenyl (369) 3,4,5 -Trihydroxyphenyl (370) 2,4,6-tributylphenyl (371) 2,4,6-tri (2-methoxy-2-ethoxyethyl) ) Phenyl (372) 2,4,6-triphenylphenyl (373) 2,4,6-triethoxycarbonylphenyl (374) 2,4,6-tridodecyloxyphenyl (375) 2,4,6-trimethyl Phenyl (376) 2,4,6-trichlorophenyl (377) 2,4,6-tribenzoylphenyl (378) 2,4,6-triacetoxyphenyl (379) 2,4,6-trimethoxyphenyl (380 ) 2,4,6-tri-N-methylaminophenyl (381) 2,4,6-triisobutyrylaminophenyl (382) 2,4,6-triphenoxyphenyl (383) 2,4,6- Trihydroxyphenyl (384) Pentafluorophenyl (385) Pentachlorophenyl (386) Pentamethoxyphenyl (38 ) 6-N-methylsulfamoyl-8-methoxy-2-naphthyl (388) 5-N-methylsulfamoyl-2-naphthyl (389) 6-N-phenylsulfamoyl-2-naphthyl (390) 5-Ethoxy-7-N-methylsulfamoyl-2-naphthyl (391) 3-methoxy-2-naphthyl (392) 1-ethoxy-2-naphthyl (393) 6-N-phenylsulfamoyl-8- Methoxy-2-naphthyl (394) 5-methoxy-7-N-phenylsulfamoyl-2-naphthyl (395) 1- (4-methylphenyl) -2-naphthyl (396) 6,8-di-N- Methylsulfamoyl-2-naphthyl (397) 6-N-2-acetoxyethylsulfamoyl-8-methoxy-2-naphthyl (398) 5-acetoxy-7- N-phenylsulfamoyl-2-naphthyl (399) 3-benzoyloxy-2-naphthyl (400) 5-acetylamino-1-naphthyl (401) 2-methoxy-1-naphthyl (402) 4-phenoxy-1 -Naphtyl (403) 5-N-methylsulfamoyl-1-naphthyl (404) 3-N-methylcarbamoyl-4-hydroxy-1-naphthyl (405) 5-methoxy-6-N-ethylsulfamoyl- 1-naphthyl (406) 7-tetradecyloxy-1-naphthyl (407) 4- (4-methylphenoxy) -1-naphthyl (408) 6-N-methylsulfamoyl-1-naphthyl (409) 3- N, N-dimethylcarbamoyl-4-methoxy-1-naphthyl (410) 5-methoxy-6-N-benzylsulfamoyl 1-naphthyl (411) 3,6-di-N-phenylsulfamoyl-1-naphthyl (412) methyl (413) ethyl (414) butyl (415) octyl (416) dodecyl (417) 2-butoxy-2 -Ethoxyethyl (418) benzyl (419) 4-methoxybenzyl

(424) Methyl (425) Phenyl (426) Butyl

(430) methyl (431) ethyl (432) butyl (433) octyl (434) dodecyl (435) 2-butoxy-2-ethoxyethyl (436) benzyl (437) 4-methoxybenzyl

  The amount of these compounds added is preferably 0.1 to 5.0% by mass, and more preferably 0.5 to 1.5% by mass with respect to the amylose ester.

(Antioxidant)
Antioxidants are also referred to as deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the retardation film may be deteriorated. The antioxidant has a role of delaying or preventing the retardation film from being decomposed by, for example, the residual solvent amount of halogen in the retardation film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain in a film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 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], 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-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-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-hydroxy Benzyl) -isocyanurate and the like. 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. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The amount of these compounds added is preferably 1 to 10000 ppm, more preferably 10 to 1000 ppm in terms of mass ratio relative to the amylose ester.

(Matting agent)
Fine particles such as a matting agent can be added to the amylose ester according to the present invention in order to impart slipperiness. Examples of the fine particles include fine particles of an inorganic compound or fine particles of an organic compound.

The amount of fine particles added is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.5 g, and still more preferably 0.08 to 0.3 g per 1 m ^{2 of the} retardation film. Thereby, it is preferable that a 0.1-1 micrometer convex part is formed in the phase difference film surface, and slipperiness is provided to a film.

  Examples of the fine particles added to the retardation film include inorganic compounds such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silica. Mention may be made of calcium acid, aluminum silicate, magnesium silicate and calcium phosphate. Among them, those containing silicon are preferable because the turbidity is low and the haze of the film can be reduced, and silicon dioxide is particularly preferable.

  In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such particles are preferable because they can reduce the haze of the film. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like.

  The silicon dioxide fine particles can be obtained, for example, by burning vaporized silicon tetrachloride and hydrogen mixed at 1000 to 1200 ° C. in the air.

  The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. The average diameter of the primary particles is more preferably 5 to 16 nm, and further preferably 5 to 12 nm. These fine particles form a secondary agglomerate in the film and form unevenness on the film surface to impart slipperiness. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is more preferably 90 to 200 g / L or more, and further preferably 100 to 200 g / L or more. Higher apparent specific gravity makes it possible to produce a high-concentration fine particle dispersion, and less haze and large aggregates are generated. In the present invention, the liter is represented by L.

  As preferable fine particles of silicon dioxide, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) manufactured by Nippon Aerosil Co., Ltd. A commercially available one can be mentioned, and Aerosil 200V, R972, R972V, R974, R202, R812 can be preferably used. The fine particles of zirconium oxide are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and any of them can be used.

  Among these, Aerosil 200V, Aerosil R972V, and Aerosil TT600 are particularly preferable because they have a large effect of lowering the turbidity and lowering the friction coefficient of the retardation film of the present invention.

  Examples of the fine particles of the organic compound include silicone resin, fluorine resin, and acrylic resin. Of these, silicone resins are preferred, and those having a three-dimensional network structure are particularly preferred. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.) Can be mentioned.

  In the measurement of the primary average particle diameter of the fine particles, the particles are observed with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), 100 particles are observed, and the average value is used as the primary average particle diameter. can do.

  Further, the apparent specific gravity described above can be calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder and measuring the weight at this time.

Apparent specific gravity (g / L) = silicon dioxide mass (g) / silicon dioxide volume (L)
The inorganic fine particles added here can impart slipperiness to the film surface, but the retardation fluctuation suppressing effect cannot be obtained. Addition of a large amount of inorganic fine particles is accompanied by an increase in aggregates and a significant increase in haze.

[Production of retardation film]
Hereinafter, the preferable manufacturing method of the retardation film of this invention is demonstrated.

1) Dissolution step In a dissolution vessel, the amylose ester and additives are dissolved in an organic solvent mainly composed of a good solvent for the amylose ester while stirring to form a dope, or the additive solution is mixed with the amylose ester solution. And forming a dope.

  For dissolving amylose ester, various dissolution methods such as a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, a method performed by the cooling dissolution method, a method performed at high pressure, etc. However, a method in which pressure is applied at a temperature equal to or higher than the boiling point of the main solvent is preferable.

  The concentration of amylose ester in the dope is preferably 10 to 35% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Moreover, you may add the whole quantity or one part of additives, such as a plasticizer and a ultraviolet absorber, to this dope. After all the materials are dissolved, they are filtered with a filter medium, defoamed, and sent to the next process with a liquid feed pump.

2) Casting process On a metal support such as an endless metal belt, such as a stainless steel belt or a rotating metal drum, the dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump). The dope is cast from the pressure die slit at the casting position.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

3) Solvent evaporation step In this step, the web is heated on the metal support, and the solvent is evaporated until the web becomes peelable from the metal support.

  In order to evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. However, the drying efficiency is preferable. A method of combining them is also preferable. In the case of backside liquid heat transfer, it is preferable to heat at or below the boiling point of the main solvent of the organic solvent used in the dope or the organic solvent having the lowest boiling point.

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process. It should be noted that if the residual solvent amount of the web at the time of peeling (the following formula) is too large, it is difficult to peel, or conversely, if it is peeled off after being sufficiently dried on the metal support, a part of the web is in the middle. It may come off.

  Here, there is a gel casting method (gel casting) as a method for increasing the film forming speed (the film forming speed can be increased by peeling while the residual solvent amount is as large as possible). For example, there are a method in which a poor solvent for amylose ester is added to the dope and the gel is cast after casting the dope, a method in which the temperature of the metal support is lowered and gelled. By gelling on the metal support and increasing the strength of the film at the time of peeling, the speed of film formation can be increased by speeding up the peeling.

  The amount of residual solvent during peeling of the web on the metal support is preferably within a range of 5 to 150% by mass depending on the strength of drying conditions, the length of the metal support, etc., but the amount of residual solvent is larger. In the case of peeling at a point in time, if the web is too soft, flatness at the time of peeling is impaired, or slippage or vertical stripes due to peeling tension are likely to occur. Therefore, the residual solvent amount at the time of peeling is determined in consideration of economic speed and quality. In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

  The residual solvent amount of the web at the peeling position is preferably 10 to 150% by mass, and more preferably 10 to 120% by mass.

  The amount of residual solvent can be represented by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the mass M is dried at 110 ° C. for 3 hours.

5) Drying and stretching process After peeling, the web is transferred using a drying device that alternately passes the web through a roll arranged in the drying device and / or a tenter device that clips and transports both ends of the web with clips. To dry.

  In this invention, it is preferable to extend | stretch using a tenter apparatus as a method of extending | stretching 1.0 to 2.0 times with respect to the width direction between clips. More preferably, it is biaxially stretched in the longitudinal and transverse directions. During biaxial stretching, the desired retardation value can also be obtained by relaxing it by 0.8 to 1.0 times in the longitudinal direction. The draw ratio is set according to the target optical characteristics (Ro, Rt). Moreover, when manufacturing the phase difference film of this invention, it can also be uniaxially stretched in the elongate direction. The retardation film of the present invention preferably has 23 ° C., 55% RH, a wavelength of 590 nm, Ro of 20 to 80 nm, and Rt of 100 to 250 nm. The temperature at the time of stretching is 80 to 180 ° C., preferably 90 to 160 ° C., and the residual solvent amount at the time of stretching is 5 to 40% by mass, preferably 10 to 30% by mass.

  As a result, it has been found that a retardation film having a stable display quality with little fluctuation in Ro and Rt can be provided as a retardation film even under conditions where the humidity varies.

  As a drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Throughout, the drying temperature is usually in the range of 40 to 250 ° C. The drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.

  Although the thickness of a film is not specifically limited, For example, a film of arbitrary thickness, such as a thing of about 10 micrometers-1 mm, can be produced. Preferably, the film thickness after drying, stretching and the like is preferably 10 to 500 μm, particularly preferably 30 to 120 μm.

[Polarizing plate and liquid crystal display]
The retardation film of the present invention can improve the viewing angle compensation function and the humidity dependency of the viewing angle compensation function, thereby being a polarizing plate protective film and simultaneously expanding the viewing angle of the liquid crystal display device. It can be used while maintaining stable performance as an optical compensation film.

(Polarizer)
The polarizing plate of the present invention will be described.

  The polarizing plate of the present invention can be produced by a general method. For example, there is a method in which a retardation film of the present invention is subjected to alkali saponification treatment and then bonded to both surfaces of a polarizing film produced by immersing and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. The alkali saponification treatment is a treatment in which the amylose ester film is immersed in a high-temperature strong alkaline solution in order to improve the wetness of the water-based adhesive and improve the adhesion.

  A conventionally well-known thing can be used as a polarizer used for the polarizing plate of this invention. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol is treated with a dichroic dye such as iodine and stretched, or a plastic film such as vinyl chloride is treated and oriented. The polarizer thus obtained is bonded to an amylose ester film.

  At this time, the retardation film of the present invention is used for at least one of the amylose ester films. Another amylose ester film or cellulose ester film can be used on the other side. The amylose ester film produced for the retardation film of the present invention may be used on the other side, or a commercially available cellulose ester film (KC8UX2M, KC4UX2M, KC5UN, KC4UY, KC8UY, KC8UY-HA, KC8UX-RHA, Konica Minolta Opto Co., Ltd.) can be used as a polarizing plate protective film on the other surface.

  In addition to the antiglare layer or the clear hard coat layer, the polarizing plate protective film used on the surface side of the display device preferably has an antireflection layer, an antistatic layer, and an antifouling layer.

(Liquid crystal display device)
The liquid crystal display device of the present invention can be produced by arranging and bonding the polarizing plate of the present invention obtained on the both sides of the liquid crystal cell.

  Moreover, at the time of producing the polarizing plate, it is preferable to bond the retardation film of the present invention so that the in-plane slow axis and the transmission axis of the polarizer are parallel or orthogonal. In this case, it is particularly preferable for production to use a long film to bond by roll-to-roll. As a result, light leakage at the time of black display is remarkably improved, and even a liquid crystal display device having a large screen of 15 type or more, preferably 19 type or more, has no white spots at the periphery of the screen, and the effect thereof. Even under an environment where the humidity fluctuation is large, a stable viewing angle characteristic is maintained for a long period of time, and a remarkable effect is recognized particularly in an MVA (multi-domain vertical alignment) type liquid crystal display device. In addition, the viewing angle characteristics of a liquid crystal display device employing various driving methods such as TN, VA, OCB, and HAN can be optimized.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

Example << Preparation of Retardation Film 101 >>
<Fine particle dispersion>
Silicon dioxide fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to prepare a fine particle dispersion.

<Fine particle additive solution>
After adding amylose ester to the dissolution tank containing methylene chloride and heating to completely dissolve it, this was added to Azumi Filter Paper No. Filtered using 244. The fine particle dispersion was slowly added thereto while sufficiently stirring the filtered amylose ester solution. Furthermore, dispersion was carried out with an attritor. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

Methylene chloride 99 parts by mass Amylose ester (see Table 1) 4 parts by mass Fine particle dispersion 11 parts by mass Next, a main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Amylose ester was charged into a pressurized dissolution tank containing a solvent while stirring. This was heated and stirred to dissolve completely, and a plasticizer and an ultraviolet absorber were further added and dissolved. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

  In addition to the mixing ratio of 100 parts by mass of the main dope solution and 2 parts by mass of the fine particle additive solution, the mixture is sufficiently mixed with an in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then the belt casting apparatus is used. Used and cast uniformly on a stainless steel band support having a width of 2 m. On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off. Tension was applied at the time of peeling, and the longitudinal (MD) stretch ratio was stretched to 1.0. Then, both ends of the web were gripped by a tenter, the residual solvent amount at the start of stretching was 20% by mass, and the temperature was 130. It extended | stretched so that the draw ratio of the width | variety (TD) direction might be 1.3 times at ° C. After stretching, hold for several seconds while maintaining its width, release the width holding after relaxing the tension in the width direction, further carry for 30 minutes in the third drying zone set at 125 ° C., and dry. A retardation film 101 having a film thickness of 80 μm having a width of 1.5 m, a knurling having a width of 1 cm at the end and a height of 8 μm was produced.

<Composition of main dope solution>
Methylene chloride 300 parts by mass Ethanol 52 parts by mass Amylose ester (see Table 1) 100 parts by mass Plasticizer A (PX861 (polyhydric alcohol ester)) 5 parts by mass Plasticizer B (Sample No. 3 (aromatic terminal ester)) 5 Part by weight UV absorber (Tinubin 109 (Ciba Specialty Chemicals Co., Ltd.))
1.3 parts by weight UV absorber (Tinubin 171 (Ciba Specialty Chemicals Co., Ltd.))
0.6 parts by mass << Preparation of retardation films 102 to 110 and polarizing plate protective film 111 >>
In the production of the retardation film 101, the amylose ester is changed to the amylose ester, cellulose ester or a mixture thereof shown in Table 1 below, the type and amount of the plasticizer shown in Table 1 below, the mixing ratio of the amylose ester and the cellulose ester, Retardation films 102 to 110 and a polarizing plate protective film 111 were produced in the same manner except that the draw ratios and film thicknesses shown in Table 2 were changed.

<< Evaluation of retardation film and polarizing plate protective film >>
The following evaluation was performed about the obtained retardation film and polarizing plate protective film.

(Ro, Rt, ΔRt)
The prepared retardation film and polarizing plate protective film were conditioned at 23 ° C. and 20% RH for 5 hours, and the Rt value measured by the following method in the same environment was defined as Rt (a). After the plate protective film was continuously conditioned at 23 ° C. and 80% RH for 5 hours, the Rt value measured in the same environment was defined as Rt (b), and the retardation value fluctuation ΔRt was determined from the following formula.

ΔRt = | Rt (a) −Rt (b) |
Furthermore, the sample after humidity control was measured again in an environment of 23 ° C. and 55% RH, and it was confirmed that this variation was a reversible variation.

  Similarly, the measurement was performed in an environment of 23 ° C. and 55% RH by changing the wavelength.

<Measuring method of Ro and Rt>
The average refractive index of the film constituting material was measured using an Abbe refractometer (4T). Moreover, the thickness of the film was measured using a commercially available micrometer.

  Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), film retardation measurement was performed at a wavelength of 590 nm in a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH. went. The average refractive index and film thickness described above were input, and the values of in-plane retardation (Ro) and retardation in the thickness direction (Rt) were obtained by the following formulas. The direction of the slow axis was also measured at the same time.

Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is Film thickness (nm).)
The evaluation results are shown in Table 2.

  From the table, it was found that the retardation film of the present invention is clearly superior in that there is little change in the retardation value with respect to humidity fluctuation as compared with the comparative example. Moreover, when the film only of amylose ester measured by changing a wavelength, it turned out that Rt value does not depend on a wavelength.

<Production of polarizing plate>
The alkali saponification treatment and the polarizing plate described below were prepared using the raw film samples of the retardation film and the polarizing plate protective film prepared as described above.

<Alkali saponification treatment>
Saponification process 2M-NaOH 50 ° C. 90 seconds Water washing process Water 30 ° C. 45 seconds Neutralization process 10% by mass HCl 30 ° C. 45 seconds Water washing process Water 30 ° C. 45 seconds Subsequently, it dried at 80 degreeC.

<Production of polarizer>
A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to form a polarizing film.

  The polarizing plate protective film 111 is bonded to one side of the polarizing film, and the retardation films 101 to 110 are bonded to the opposite side using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive, dried, and polarizing plates P101 to P101. 110 was produced. Moreover, the polarizing plate P111 which bonded the polarizing plate protective film 111 on both surfaces of the polarizing film was produced similarly.

<Production of liquid crystal display device>
The polarizing plates on both sides of the 15-inch display VL-150SD manufactured by Fujitsu were peeled off in advance, and the above-prepared polarizing plates P101 to P111 having the configuration shown in Table 3 were each bonded to the glass surface of the liquid crystal cell (VA type). Thus, liquid crystal display devices D101 to D111 were produced.

  At that time, the direction of bonding of the polarizing plate is such that the surface on which the retardation film is bonded is on the liquid crystal cell side, and the absorption axis is directed in the same direction as the polarizing plate previously bonded. Then, liquid crystal display devices D101 to D111 were manufactured in combinations shown in Table 3 below.

<Evaluation of liquid crystal display device>
<Deterioration of viewing angle>
The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. Subsequently, the viewing angle of the produced liquid crystal display device (commercial panel + self-made elliptical polarizing plate) was measured in an environment of 23 ° C., 20% RH, and further 23 ° C., 80% RH, and evaluated according to the following criteria. Finally, viewing angle measurement was performed again in an environment of 23 ° C. and 55% RH, and it was confirmed that the change during the measurement was reversible fluctuation. These measurements were made after the liquid crystal display device was placed in the environment for 5 hours.

○: No viewing angle variation ×: Viewing angle variation is recognized Table 3 shows the evaluation results.

  From the table, it is clear that the liquid crystal display device of the present invention does not fluctuate the viewing angle even under the condition of changing humidity, and exhibits extremely stable display performance.

Claims (6)

A retardation film comprising amylose ester. The retardation film according to claim 1, wherein the amylose ester has a total acyl group substitution degree of 2.0 to 3.0. The retardation film according to claim 1, wherein Ro is 20 to 80 nm and Rt is 100 to 250 nm at 23 ° C. and 55% RH at a wavelength of 590 nm.
Ro = (nx−ny) × d
Rt = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is Film thickness (nm).) A polarizing plate comprising the retardation film according to claim 1 on at least one surface of a polarizer. A liquid crystal display device comprising the retardation film according to claim 1. 6. The liquid crystal display device according to claim 5, wherein the liquid crystal cell is a VA liquid crystal cell.