JP2007245539A - Cellulose ester film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film as a retardation film capable of enhancing the front face contrast of a liquid crystal display by suppressing leak of light from a polarizing plate, in a cellulose ester film which can be used in the liquid crystal display (LCD), in particular, a liquid crystal display of a VA model (vertical orientation mode) etc., and a cellulose ester film manufacturing method. <P>SOLUTION: This method comprises a film drawing process in which the film is drawn, retained and eased in the width direction while continuously conveying the film with the end part of the film held by a clip, and then, is taken up. In the film drawing process, the film is drawn on the condition that the product of the film drawing speed of X (m/min) and the draw ratio of Y(%) meets formula (1) 45≤X×Y≤450. In the formula, the draw ratio of X means the value obtained by dividing the increment (m) of the draw by the time (min) spent for drawing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used as a cellulose ester film used in various display devices such as a liquid crystal display device (LCD) or an organic EL (electroluminescence) display, particularly as a protective film for a polarizing plate and a retardation film used in these display devices. The present invention relates to a birefringent cellulose ester film and a method for producing the same.

  In general, the basic configuration of a liquid crystal display device is one in which polarizing plates are provided on both sides of a liquid crystal cell. Since the polarizing plate allows only light with a polarization plane in a certain direction to pass, it plays an important role in visualizing changes in the orientation of the liquid crystal due to the electric field in the liquid crystal display device. The performance of the liquid crystal display device depends on the performance of the polarizing plate. Is greatly affected.

  In recent years, demand for display quality of thin-film liquid crystal display devices has increased, and various liquid crystal display methods such as VA (vertical alignment mode), OCB, and IPS have been proposed. In a liquid crystal display device with a wide viewing angle, it is common to use a retardation correction film. The quality required for retardation films has become stricter due to the larger screen and higher definition, and the uniformity of the film retardation value in the width direction and the longitudinal direction is required.

  The market of liquid crystal display devices is rapidly expanding as an image device with low power consumption and space saving. At the same time, the required characteristics of the retardation film, which is one of the members constituting the liquid crystal display device, are further increased, and improvements in functions such as improved polarization characteristics, higher contrast, and wider viewing angle are required.

  In particular, the front contrast of the liquid crystal display device can be improved by suppressing light leakage from the polarizing plate. To that end, it is important to quickly orient the cellulose ester resin in one direction. The orientation of the cellulose ester resin can be increased by increasing the draw ratio of the film in the film drawing process. However, increasing the draw ratio of the film also increases the haze value of the film. There was a problem that the transparency deteriorated.

Conventionally, as a measure for improving the front contrast of a liquid crystal display device, various requirements and proposals have been made for transparency, retardation value, elastic modulus ratio, etc. of a retardation film, and there are the following patent documents.
Japanese Patent Laid-Open No. 10-312166 discloses a liquid crystal display device and an optical compensation sheet, and describes that the front contrast of the liquid crystal display device decreases when the in-plane retardation of the optical compensation sheet is large. ing. JP-A-9-230333 discloses a liquid crystal element using an optically anisotropic element, and describes the relationship between the haze of the film and the front contrast of the liquid crystal display device. JP-A-2002-71954 discloses an optical compensation sheet, a polarizing plate, and a liquid crystal display device, and describes that the front contrast of the liquid crystal display device is improved by using a retardation adjusting agent. ing. JP-A-2003-55477 discloses a cellulose ester film, an optical compensation sheet, a polarizing plate, and a liquid crystal display device. In order to improve light leakage of the polarizing plate, It is described that it is preferable to stretch the film at a low speed.

  However, the techniques described in Patent Documents 1 to 4 are insufficient to improve a polarizing plate that suppresses light leakage and a VA type (vertical alignment mode) liquid crystal display device that improves front contrast. There was a problem that there was.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and by the technical innovation of the cellulose ester film forming technology, particularly the uniaxial stretching technology in the direction perpendicular to the conveying direction in the film stretching process, An object of the present invention is to provide a cellulose ester film as a retardation film that suppresses leakage and improves the front contrast of a liquid crystal display device, and a method for producing the same. Accordingly, an object of the present invention is to provide a polarizing plate that suppresses light leakage and a liquid crystal display device with improved front contrast, particularly a VA (vertical alignment mode) liquid crystal display device.

  As a result of intensive studies to solve the above-mentioned problems of the prior art, the inventor of the present invention has produced a cellulose ester film by controlling the stretching speed in the film stretching process. It can be improved, and by controlling it together with the draw ratio of the film, crystallization of the cellulose ester resin and micro phase separation of the polymer and additive are suppressed, and while maintaining the transparency of the film, light leakage is prevented. The inventors have found that a retardation film composed of a small amount of cellulose ester film can be obtained, and have completed the present invention.

In order to achieve the above object, the invention of claim 1 is characterized in that in the film stretching step, the film end is gripped by a clip and stretched / held / relaxed in the width direction while being continuously conveyed, and then the film is wound. A method for producing a cellulose ester film, wherein in the film stretching step, the product of film stretching speed: X (m / min) and stretching ratio: Y (%) is represented by the following formula (1):
45 ≦ X × Y ≦ 450 (1)
Here, stretching speed: X means a value obtained by dividing the increment (m) by stretching by the time (min) required for stretching.

The film is stretched under the conditions satisfying the above conditions.

Invention of Claim 2 is a manufacturing method of the cellulose-ester film of the said Claim 1, Comprising: In a film extending process, extending | stretching temperature: T (degreeC) is with respect to a glass transition point: Tg (degreeC). Following formula (2)
1 ≦ Tg−T ≦ 30 (2)
The film is stretched under the conditions satisfying the above conditions.

  Invention of Claim 3 is a manufacturing method of the cellulose-ester film of Claim 1 or 2, Comprising: The total substitution degree of the acyl group of the cellulose ester to be used is 2.40-2.70, Among them, an acyl group The degree of substitution of those having 3 or more carbon atoms is 0 to 1.1.

Invention of Claim 4 is the cellulose-ester film manufactured with the manufacturing method as described in any one of Claims 1-3, Comprising: Elastic modulus in the slow axis direction in a film surface: (epsilon) s, The modulus of elasticity in the fast axis direction: the difference from εf is the following formula (3)
700 ≦ εs−εf ≦ 2450 (3)
It is characterized by satisfying the relationship.

The invention of claim 1 is the film stretching step in the method for producing a cellulose ester film, wherein the product of the film stretching speed: X (m / min) and the stretching ratio: Y (%) is represented by the following formula (1):
45 ≦ X × Y ≦ 450 (1)
Here, stretching speed: X means a value obtained by dividing the increment (m) by stretching by the time (min) required for stretching.

The film is stretched under the conditions satisfying the conditions. According to the present invention, in the production of a cellulose ester film, the orientation of the film can be improved by controlling the stretching speed in the film stretching step. By controlling together with the draw ratio of the film, crystallization of the cellulose ester resin and micro phase separation of the polymer and additives are suppressed, and while maintaining the transparency of the film, the cellulose ester film has less light leakage. There is an effect that a retardation film is obtained.

  In addition, according to the present invention, the light leakage of the polarizing plate is suppressed by the technical innovation of the cellulose ester film forming technology, particularly the uniaxial stretching technology in the direction perpendicular to the transport direction in the film stretching process, and the liquid crystal display device There exists an effect that the cellulose-ester film as a phase difference film which improved front contrast can be obtained.

Invention of Claim 2 is a manufacturing method of the cellulose-ester film of the said Claim 1, Comprising: In a film extending process, extending | stretching temperature: T (degreeC) is with respect to a glass transition point: Tg (degreeC). Following formula (2)
1 ≦ Tg−T ≦ 30 (2)
According to the present invention, if the stretching temperature: T (° C.) is within the above range, no residual stress remains in the film during stretching, and the polarizing plate There is no frame-like light leakage, and the front contrast of the liquid crystal display device is improved.

  Invention of Claim 3 is a manufacturing method of the cellulose-ester film of Claim 1 or 2, Comprising: The total substitution degree of the acyl group of the cellulose ester to be used is 2.40-2.70, Among them, an acyl group The degree of substitution of those having 3 or more carbon atoms is 0 to 1.1. According to the present invention, by using a cellulose ester in which the total degree of substitution of the acyl group is defined as above, While maintaining the transparency of the film, there is an effect that a retardation film made of a cellulose ester film with little light leakage is obtained.

Invention of Claim 4 is the cellulose-ester film manufactured with the manufacturing method as described in any one of Claims 1-3, Comprising: Elastic modulus in the slow axis direction in a film surface: (epsilon) s, The modulus of elasticity in the fast axis direction: the difference from εf is the following formula (3)
700 ≦ εs−εf ≦ 2450 (3)
According to the present invention, the cellulose ester film has a high retardation value, a sufficient tear strength, and an excellent rework performance when producing a polarizing plate. .

  Furthermore, according to the present invention, it is an object of the present invention to provide a polarizing plate that suppresses light leakage, and in particular, a VA liquid crystal display device with improved front contrast.

  Next, embodiments of the present invention will be described, but the present invention is not limited thereto.

  The present invention relates to a technique for forming a cellulose ester film, and more particularly to a uniaxial stretching technique in a direction perpendicular to the conveying direction in a film stretching process, and suppresses light leakage of a polarizing plate and improves the front contrast of a liquid crystal display device. The present invention provides a cellulose ester film as a retardation film and a method for producing the same, and further provides a polarizing plate that suppresses light leakage and a VA type (vertical alignment mode) liquid crystal display device that improves front contrast. It is.

In the film stretching step of the cellulose ester film forming method of the present invention, the product of the film stretching speed: X (m / min) and the stretching ratio: Y (%) is expressed by the following formula (1).
45 ≦ X × Y ≦ 450 (1)
Here, stretching speed: X means a value obtained by dividing the increment (m) by stretching by the time (min) required for stretching.

The film is stretched under the conditions satisfying the above conditions.

  Thus, in the film stretching process, the orientation of the film can be improved by controlling the stretching speed. By controlling the stretching ratio of the film, the crystallization of the cellulose ester resin and the polymer And a phase difference film made of a cellulose ester film with little light leakage while suppressing the micro phase separation of the additive and maintaining the transparency of the film.

In the method of the present invention, in the film stretching step, the stretching temperature: T (° C.) is the following formula (2) with respect to the glass transition point: Tg (° C.).
1 ≦ Tg−T ≦ 30 (2)
It is preferable to stretch the film under conditions that satisfy the above conditions.

  These will be described in detail below.

  The retardation film made of the cellulose ester film according to the present invention is preferably a polymer film, among which it is easy to produce, good adhesion with a polarizing film, optical transparency and the like. It is preferable.

  The term “transparent” as used in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

  The polymer film is not particularly limited as long as it has the above-mentioned properties, for example, a cellulose ester film such as a cellulose diacetate film, a cellulose triacetate film, a cellulose acetate butyrate film, and a cellulose acetate propionate film, Polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol Film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate Bonate film, cycloolefin polymer film (Arton (manufactured by JSR), ZEONEX, ZEONOR (manufactured by ZEON CORPORATION), polymethylpentene film, polyetherketone film, polyetherketoneimide film, polyamide film, fluororesin film , Nylon film, polymethyl methacrylate film, acrylic film, glass plate, etc. Among them, cellulose ester film, cycloolefin polymer film, polycarbonate film, polysulfone (including polyethersulfone) film are preferable, In the present invention, a cellulose ester film, a cycloolefin polymer film, and a polycarbonate film are particularly advantageous in terms of production, cost, and transparency. Preferably used from the viewpoint of adhesiveness. These films may be a film produced by melt casting film forming method, it may be a film produced by a solution casting film forming method.

  The retardation film of the present invention is an optical film such as polyamide or polyimide as a polymer layer on the film described in JP-A-2000-190385, JP-A-2004-4474, JP-A-2005-19581, and the like. A polymer film provided with an anisotropic layer is also preferred.

[Cellulose ester film]
Preferred cellulose esters as the main component of the retardation film comprising the cellulose ester film according to the present invention are cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, and cellulose acetate propionate, and among them cellulose acetate butyrate Cellulose acetate phthalate and cellulose acetate propionate are preferably used.

  In particular, a transparent film substrate having a mixed fatty acid ester of cellulose in which P and Q are in the following ranges when the substitution degree of the acetyl group is P and the substitution degree of the propionyl group or butyryl group is Q is preferably used.

Formula (I) 2.0 ≦ P + Q ≦ 2.7
Formula (II) 0.1 ≦ Q ≦ 1.2
Furthermore, cellulose acetate propionate (total acyl group substitution degree = P + Q) of 2.4 ≦ P + Q ≦ 2.7 and 1.4 ≦ P ≦ 2.3 is preferable.

  Among them, 2.4 ≦ P + Q ≦ 2.7, 1.7 ≦ P ≦ 2.3, 0.1 ≦ Q ≦ 0.9, cellulose acetate propionate, cellulose acetate butyrate (total acyl group substitution degree = P + Q) ) Is preferred.

  In the method for producing a cellulose ester film of the present invention, the total substitution degree of the acyl group of the cellulose ester used is 2.40 to 2.70, and the substitution degree of the acyl group having 3 or more carbon atoms is 0 to 0. 1.1 is preferred. Thus, by using the cellulose ester in which the total substitution degree of the acyl group is defined, a retardation film made of a cellulose ester film with little light leakage can be obtained while maintaining the transparency of the film.

  The portion not substituted with an acyl group usually exists as a hydroxyl group. These cellulose esters can be synthesized by a known method.

  When cellulose ester is used as the retardation film comprising the cellulose ester film according to the present invention, cellulose as a raw material for cellulose ester is not particularly limited, but cotton linter, wood pulp (derived from coniferous tree, derived from broadleaf tree), kenaf, etc. Can be mentioned. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), these cellulose esters use an organic solvent such as acetic acid or an organic solvent such as methylene chloride, and It can be obtained by reacting with a cellulose raw material using a protic catalyst.

When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804. In addition, the cellulose ester used in the present invention is obtained by mixing and reacting the amount of the acylating agent in accordance with the degree of substitution. In the cellulose ester, these acylating agents react with hydroxyl groups of cellulose molecules. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution (mol%). For example, cellulose triacetate has acetyl groups bonded to all three hydroxyl groups of the glucose unit (actually 2.6 to 3.0).

  As the cellulose ester used in the present invention, as described above, cellulose having propionate group or butyrate group in addition to acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate is used. The mixed fatty acid ester is particularly preferably used. Cellulose acetate propionate containing a propionate group as a substituent has excellent water resistance and is useful as a film for a liquid crystal image display device.

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

  The number average molecular weight of the cellulose ester is preferably 40,000 to 200,000, and the mechanical strength when molded is strong, and an appropriate dope viscosity is preferable in the case of the solution casting method, and more preferably 50,000 to 150,000. The weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably in the range of 1.4 to 4.5.

  These cellulose esters are pressurized by applying a cellulose ester solution (dope) generally called a solution casting film forming method onto, for example, an endless metal belt for infinite transport or a support for casting of a rotating metal drum. It is preferable to manufacture the dope from a die by casting (casting).

  As the organic solvent used for preparing these dopes, it is preferable that the cellulose ester can be dissolved and has an appropriate boiling point. For example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, methyl acetoacetate, acetone, tetrahydrofuran 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-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, 1,3-dimethyl-2-imidazolidinone, etc. Can, organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate, acetone, methyl acetoacetate, and the like are preferable organic solvents (i.e., good solvent), and as.

  Moreover, as shown in the following film forming process, it is used from the viewpoint of preventing foaming in the web when the solvent is dried from the web (dope film) formed on the casting support in the solvent evaporation process. The boiling point of the organic solvent is preferably 30 to 80 ° C. For example, the good solvent described above has a boiling point of methylene chloride (boiling point 40.4 ° C), methyl acetate (boiling point 56.32 ° C), acetone (boiling point 56.56 ° C). 3 ° C.), ethyl acetate (boiling point 76.82 ° C.) and the like.

  Among the good solvents described above, methylene chloride or methyl acetate, which is excellent in solubility, is preferably used.

  It is preferable to contain 0.1 mass%-40 mass% of C1-C4 alcohol other than the said organic solvent. It is particularly preferable that the alcohol is contained at 5 to 30% by mass. After casting the dope described above onto a casting support, the solvent starts to evaporate and the alcohol ratio increases and the web (dope film) gels, making the web strong and peeling from the casting support. It is also used as a gelling solvent for facilitating the dissolution, and when these ratios are small, it also has a role of promoting the dissolution of the cellulose ester of the non-chlorine organic solvent.

  Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like.

  Of these solvents, ethanol is preferred because the dope has good stability, the boiling point is relatively low, and the drying property is good. It is preferable to use a solvent containing 5% by mass to 30% by mass of ethanol with respect to 70% by mass to 95% by mass of methylene chloride. Methyl acetate can be used in place of methylene chloride. At this time, the dope may be prepared by a cooling dissolution method.

  As the plasticizer used in the present invention, a phosphate ester plasticizer and a non-phosphate ester plasticizer are preferably used.

  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.

  Non-phosphate ester plasticizers include phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers, glycolate plasticizers, and citrate ester plasticizers. Agents, fatty acid ester plasticizers, polyester plasticizers, polycarboxylic acid ester plasticizers and the like can be preferably used. Particularly, in order to obtain the effects of the present invention, polyhydric alcohol plasticizers, polyesters are preferable. It is preferable to use a plasticizer and a polycarboxylic acid 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
(However, 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. Of these, trimethylolpropane and pentaerythritol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for the polyhydric alcohol ester of this invention, 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. The use of acetic acid is preferred because the compatibility with the cellulose ester is increased, and it is also preferred 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 in the range of 300 to 1500, and more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose 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 according to the present invention is preferably 1 to 15% by mass, particularly preferably 3 to 10% by mass in the cellulose ester film.

(Polyester plasticizer)
The polyester plasticizer is not particularly limited, but a polyester 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 polyester 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.)
In the general formula (2), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester 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. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester 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 , 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

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

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester used in the present invention include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are each used as one or a mixture of two or more. 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 polyester 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 preferred aromatic terminal ester plasticizers for 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 No. 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 No. 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 No. 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 used for this invention below is shown, this invention is not limited to this.

  The polyvalent carboxylic acid plasticizer useful in the present invention comprises a divalent or higher, preferably a divalent to valent 20 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 (3).

General formula (3) R ₅ (COOH) m (OH) n
(Note that 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 the polyhydric carboxylic acid ester compound used for this invention, Well-known alcohol and phenol 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 cellulose 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.

  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 cellulose derivative, the effect of reducing the moisture permeability of the film is small, which is not preferable. If the amount exceeds 20% by mass, the plasticizer bleeds out from the film and the physical properties of the film are reduced. Since it deteriorates, 1-20 mass% is preferable. 6-16 mass% is further more preferable, Most preferably, it is 8-13 mass%.

  An ultraviolet absorber is preferably used for the retardation film of the present invention.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties.

  Specific examples of the ultraviolet absorber preferably used in the present invention include 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.

  Specific examples of the benzotriazole-based ultraviolet absorbers include the following ultraviolet absorbers, but the present invention is not limited thereto.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6 (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171, manufactured by Ciba)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- 4-Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN109, manufactured by Ciba)
Moreover, although the following specific example is shown as a benzophenone series ultraviolet absorber, this invention is not limited to these.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
As the ultraviolet absorber preferably used in the present invention, a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber that are highly transparent and excellent in preventing the deterioration of the polarizing plate and the liquid crystal are preferable, and unnecessary coloring is less. A benzotriazole-based ultraviolet absorber is particularly preferably used.

  Moreover, the ultraviolet absorber whose distribution coefficient described in Unexamined-Japanese-Patent No. 2001-187825 is 9.2 or more improves the surface quality of a long film, and is excellent also in applicability | paintability. In particular, it is preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

  Further, the polymer ultraviolet absorbers described in the general formula (1) or general formula (2) described in JP-A-6-148430 and the general formulas (3), (6), and (7) described in JP-A-2002-47357 ( Or UV-absorbing polymers) or UV-absorbing copolymer polymers described in paragraphs [0027] to [0055] of JP-A No. 2002-169020 are also preferably used. As a polymer ultraviolet absorber, PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) and the like are commercially available.

  An antioxidant can be used in the retardation film of the present invention. When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the polarizing plate protective film may be deteriorated. The antioxidant has a role of delaying or preventing the polarizing plate protective film from being decomposed by, for example, the residual solvent amount of halogen in the polarizing plate protective film or phosphoric acid of the phosphoric acid plasticizer. It is preferable to make it contain in a polarizing plate protective 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 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose derivative.

  Moreover, in order to provide slipperiness to the retardation film which consists of a cellulose-ester film by this invention, it is preferable to use microparticles | fine-particles.

  The primary average particle diameter of the fine particles added to the retardation film made of the cellulose ester film according to the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm. These fine particles preferably form secondary particles having a particle diameter of 0.1 to 5 μm and are contained in the retardation film, and a preferable average particle diameter is 0.1 to 2 μm, more preferably 0.2 to 0.6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface.

  The primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. The value was taken as the primary average particle size.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A larger apparent specific gravity makes it possible to make a high-concentration dispersion, which improves haze and agglomerates, and is preferable when preparing a dope having a high solid content concentration as in the present invention. Are particularly preferably used.

  Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, it is marketed with the brand name of Aerosil 200V and Aerosil R972V (above, Nippon Aerosil Co., Ltd.), and can use them.

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

Apparent specific gravity (g / liter) = silicon dioxide mass (g) / volume of silicon dioxide (liter)
Examples of the method for preparing the fine particle dispersion used in the present invention include the following three types.

<< Preparation Method A >>
After stirring and mixing the solvent and the fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.

<< Preparation Method B >>
After stirring and mixing the solvent and the fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose triacetate is added to the solvent and dissolved by stirring. The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

<< Preparation Method C >>
Add a small amount of cellulose triacetate to the solvent and dissolve with stirring. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

  Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate. Among them, the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and difficulty in reaggregation of the silicon dioxide fine particles.

《Distribution method》
The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, and most preferably 15% by mass to 20% by mass. A higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

  The addition amount of silicon dioxide fine particles relative to cellulose ester is preferably 0.01 parts by mass to 5.0 parts by mass, and more preferably 0.05 parts by mass to 1.0 part by mass with respect to 100 parts by mass of cellulose ester. Preferably, 0.1 mass part-0.5 mass part is the most preferable. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.

  As the disperser, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing silicon dioxide fine particles, a medialess disperser is preferred because of its low haze. Examples of the media disperser include a ball mill, a sand mill, and a dyno mill. Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube.

  When processing with a high-pressure dispersion apparatus, for example, the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 19.613 MPa or more. Further, at that time, those having a maximum reaching speed of 100 m / second or more and those having a heat transfer speed of 420 kJ / hour or more are preferable.

  The high-pressure dispersion apparatus as described above includes an ultra-high pressure homogenizer manufactured by Microfluidics Corporation (trade name: Microfluidizer) or a nanomizer manufactured by Nanomizer, and a Manton Gorin type high-pressure dispersion apparatus such as a homogenizer manufactured by Izumi Food Machinery. UHN-01 manufactured by Sanwa Machinery Co., Ltd.

  In addition, casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.

  Moreover, after peeling and drying after casting, and winding up in a roll shape, functional thin films, such as a hard-coat layer and an antireflection layer, are provided. Until processing or shipment, packaging is usually performed in order to protect the product from dirt, static electricity, and the like. The packaging material is not particularly limited as long as the above purpose can be achieved, but a material that does not hinder volatilization of the residual solvent from the film is preferable. Specific examples include polyethylene, polyester, polypropylene, nylon, polystyrene, paper, various non-woven fabrics, and the like. Those in which the fibers are mesh cloth are more preferably used.

  The retardation film of the present invention preferably contains a retardation control agent to adjust the retardation.

(Bar compound)
The retardation film of the present invention preferably contains a rod-like compound having a maximum absorption wavelength (λmax) of the ultraviolet absorption spectrum of the solution shorter than 250 nm as a retardation control agent.

  From the viewpoint of the function of the retardation control agent, the rod-like compound preferably has at least one aromatic ring, and more preferably has at least two aromatic rings. The rod-like compound preferably has a linear molecular structure. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation.

  For example, molecular orbital calculation is performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited), and a molecular structure that minimizes the heat of formation of a compound can be obtained. The molecular structure being linear means that the angle of the molecular structure is 140 degrees or more in the thermodynamically most stable structure obtained by calculation as described above. The rod-shaped compound preferably exhibits liquid crystallinity. More preferably, the rod-like compound exhibits liquid crystallinity upon heating (has thermotropic liquid crystallinity). The liquid crystal phase is preferably a nematic phase or a smectic phase.

  As the rod-like compound, a trans-1,4-cyclohexanedicarboxylic acid ester compound represented by the following general formula (4) is preferable.

Formula (4) Ar1-L1-Ar2
In the general formula (4), Ar1 and Ar2 are each independently an aromatic group. In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group. An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally 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. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. 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 Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included. As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino groups (eg, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (eg, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (eg, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl, Butyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl groups (eg, vinyl, allyl, hexenyl), alkynyl groups (eg, ethynyl, butynyl), acyl groups (eg, formyl, acetyl, Butyryl, hexanoyl, lauryl), acyloxy groups (eg, acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy), aryloxy groups (Eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl), aryloxycarbo Group (eg, phenoxycarbonyl), alkoxycarbonylamino group (eg, butoxycarbonylamino, hexyloxycarbonylamino), alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio), arylthio group (eg, , Phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamide, butylamide group, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

  Substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthios. And groups and alkyl groups are preferred. The alkyl moiety of the alkylamino group, alkoxycarbonyl group, alkoxy group, and alkylthio group and the alkyl group may further have a substituent. Examples of alkyl moieties and substituents of alkyl groups include halogen atom, hydroxyl, carboxyl, cyano, amino, alkylamino group, nitro, sulfo, carbamoyl, alkylcarbamoyl group, sulfamoyl, alkylsulfamoyl group, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group and non-aromatic An aromatic heterocyclic group is included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

  In the general formula (4), L1 is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, a divalent saturated heterocyclic group, —O—, —CO—, and combinations thereof. is there. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group. The number of carbon atoms of the alkylene group is preferably 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, 6 is most preferred.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure. The number of carbon atoms of the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, still more preferably 2 to 6, and still more preferably 2 to 4. Most preferred is 2 (vinylene or ethynylene). The divalent saturated heterocyclic group preferably has a 3- to 9-membered heterocyclic ring. The hetero atom of the hetero ring is preferably an oxygen atom, a nitrogen atom, a boron atom, a sulfur atom, a silicon atom, a phosphorus atom or a germanium atom. Examples of saturated heterocycles include piperidine ring, piperazine ring, morpholine ring, pyrrolidine ring, imidazolidine ring, tetrahydrofuran ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, tetrahydrothiophene ring, 1 , 3-thiazolidine ring, 1,3-oxazolidine ring, 1,3-dioxolane ring, 1,3-dithiolane ring and 1,3,2-dioxaborolane. Particularly preferred divalent saturated heterocyclic groups are piperazine-1,4-diylene, 1,3-dioxane-2,5-diylene and 1,3,2-dioxaborolane-2,5-diylene.

  The example of the bivalent coupling group which consists of a combination is shown.

L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-
L-7: -O-CO-divalent saturated heterocyclic group -CO-O-
L-8: -CO-O-divalent saturated heterocyclic group -O-CO-
In the molecular structure of the general formula (4), the angle formed by Ar1 and Ar2 across L1 is preferably 140 degrees or more. As the rod-like compound, a compound represented by the following general formula (5) is more preferable.

Formula (5) Ar1-L2-X-L3-Ar2
In the general formula (5), Ar1 and Ar2 are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar1 and Ar2 in the general formula (4).

  In the general formula (5), L 2 and L 3 are each independently a divalent linking group selected from the group consisting of an alkylene group, —O—, —CO—, and combinations thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, still more preferably 1 to 4, and 1 or Most preferred is 2 (methylene or ethylene). L2 and L3 are particularly preferably —O—CO— or —CO—O—.

  In the general formula (5), X is 1,4-cyclohexylene, vinylene or ethynylene.

  Production of the retardation film of the present invention is a step of preparing a dope by dissolving an additive such as cellulose ester and the plasticizer in a solvent, a step of casting the dope on a belt-shaped or drum-shaped metal support, It is performed by a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching, a step of further drying, a step of further heat-treating the obtained film, and a step of winding after cooling. The retardation film of the present invention preferably contains 70 to 95% by mass of cellulose ester in the solid content.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy increases. Becomes worse. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope of the present invention may be used alone or in combination of two or more. However, it is preferable from the viewpoint of production efficiency that a good solvent and a poor solvent of cellulose ester are mixed and used. The more solvent is preferable from the viewpoint of solubility of the cellulose ester. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent. Therefore, depending on the acyl group substitution degree of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4) and the cellulose acetate propionate are good. As a solvent, cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. Further, a method in which a cellulose ester is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressure is more preferably Pa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent does not boil and foam.

  A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate. A preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use hot water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%. 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.

  In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Moreover, in the drying process of the cellulose ester film, the web is peeled from the metal support, further dried, and dried until the residual solvent amount is 0.5% by mass or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  When peeling from the metal support, the web is stretched in the longitudinal direction by the peeling tension and the subsequent conveying tension. Therefore, in the present invention, when peeling the web from the casting support, the peeling and conveying tension is lowered as much as possible. It is preferable to carry out in the state. Specifically, for example, it is effective to set it to 50 to 170 N / m or less. At that time, it is preferable to apply a cold air of 20 ° C. or less to fix the web rapidly.

  An example of a stretching process (also referred to as a tenter process) for producing a retardation film made of a cellulose ester film according to the present invention will be described with reference to FIG.

  In FIG. 2, step A is a step of gripping the web conveyed from the web conveyance step D0 (not shown). In the next step B, the web is stretched in the width direction (at the stretching angle as shown in FIG. In the process C, the stretching is completed and the web is transported while being held.

In the film stretching step of the cellulose ester film forming method of the present invention, the product of the film stretching speed: X (m / min) and the stretching ratio: Y (%) is expressed by the following formula (1).
45 ≦ X × Y ≦ 450 (1)
Here, stretching speed: X means a value obtained by dividing the increment (m) by stretching by the time (min) required for stretching.

The film is stretched under the conditions satisfying the above conditions.

  In the above formula (1), if the product of the film stretching speed X (m / min) and the stretching ratio Y (%): X × Y is less than 45, high-speed productivity is poor and display unevenness occurs. It is not preferable. Moreover, since the transparency of a film will deteriorate when the product of film stretching speed: X and draw ratio Y: X * Y exceeds 450, it is unpreferable.

  Thus, in the film stretching process, the orientation of the film can be improved by controlling the stretching speed. By controlling the stretching ratio of the film, the crystallization of the cellulose ester resin and the polymer And a phase difference film made of a cellulose ester film with little light leakage while suppressing the micro phase separation of the additive and maintaining the transparency of the film.

In the method of the present invention, in the film stretching step, the stretching temperature: T (° C.) is the following formula (2) with respect to the glass transition point: Tg (° C.).
1 ≦ Tg−T ≦ 30 (2)
It is preferable to stretch the film under conditions that satisfy the above conditions.

  In the above formula (2), the difference between the glass transition point Tg (° C) and the stretching temperature T (° C): If Tg-T is less than 1, the stretching temperature T (° C) is the glass transition point Tg (° C). This is not preferable because the orientation of the film is disturbed by thermal motion and the front contrast is lowered. Conversely, if the difference between the glass transition point Tg (° C.) and the stretching temperature T (° C.): Tg-T is stretched in a state exceeding 30, residual stress remains considerably, and frame-like light leakage is confirmed, Since it cannot be used as a product, it is not preferable.

  Next, it is preferable to provide a slitter for cutting off the end in the web width direction after the web is peeled from the casting support and before the start of the process B and / or immediately after the process C. In particular, it is preferable to provide a slitter that cuts off the end of the web immediately before the start of step A. When the same stretching in the width direction is performed, particularly when the web edge is cut before the start of the process B and the condition where the web edge is not cut are compared, the former is more distributed in the optical slow axis (orientation angle). The effect of improving the distribution is also obtained.

  This is considered to be an effect of suppressing unintended stretching in the longitudinal direction from the peeling with a relatively large amount of residual solvent to the width stretching step B.

  In the tenter process, it is also preferable to intentionally create compartments with different temperatures in order to improve the orientation angle distribution. It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

  In addition, extending | stretching operation may be divided | segmented and implemented in multiple steps, and it is preferable to implement biaxial stretching in a casting direction and a width direction. Also, when biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

  In order to obtain the effect of the present invention, it is particularly preferable that the web peeled from the metal support is conveyed while being dried, and further stretched in the width direction by a tenter method in which both ends of the web are gripped by pins or clips. A predetermined phase difference can be imparted. At this time, it may be stretched only in the width direction, or simultaneous biaxial stretching is also preferred. The preferred draw ratio is preferably 1.05 to 2 times, and preferably 1.15 to 1.5 times. In the simultaneous biaxial stretching, the film may be contracted in the longitudinal direction, or may be contracted so as to be 0.8 to 0.99, preferably 0.9 to 0.99. Preferably, the area is preferably 1.12 times to 1.44 times, more preferably 1.15 times to 1.32 times, due to transverse stretching and longitudinal stretching or shrinkage. This can be determined by the draw ratio in the longitudinal direction × the draw ratio in the transverse direction.

  In addition, the “stretch direction” in the present invention is usually used to mean a direction in which a stretching stress is directly applied in the case of performing a stretching operation. In other words, it may be used in the sense of the one having a higher draw ratio (that is, the direction usually serving as the slow axis).

  When the web is stretched in the width direction, it is well known that the orientation angle distribution deteriorates in the width direction of the web. In order to carry out the widthwise stretching in a state where the values of Rt and Ro are a constant ratio and the orientation angle distribution is good, there is a preferable web temperature relative relationship in steps A, B and C. When the web temperatures at the end points of Steps A, B, and C are Ta ° C., Tb ° C., and Tc ° C., respectively, it is preferable that Ta ≦ Tb−10. Moreover, it is preferable that Tc ≦ Tb. More preferably, Ta ≦ Tb−10 and Tc ≦ Tb.

  In order to improve the orientation angle distribution, the web heating rate in step B is preferably in the range of 0.5 to 10 ° C./second.

  The stretching time in step B is preferably a short time. However, from the viewpoint of web uniformity, the minimum required stretching time range is defined. Specifically, the range is preferably 1 to 10 seconds, and more preferably 4 to 10 seconds. Moreover, as for the temperature of the process B and the process C, it is effective that the temperature of this film is the range of -30 to -1 degreeC of glass transition points, Preferably it is 100 to 160 degreeC.

  In the tenter process, the heat transfer coefficient may be constant or changed. The heat transfer coefficient preferably has a heat transfer coefficient in the range of 41.9 to 419 × 10 3 J / m 2 hr. More preferably, it is in the range of 41.9 to 209.5 × 10 3 J / m 2 hr, and most preferably in the range of 41.9 to 126 × 10 3 J / m 2 hr.

  The stretching speed in the width direction in Step B may be constant or may be changed. The stretching speed is preferably 50 to 500% / min, more preferably 100 to 400% / min, and most preferably 200 to 300% / min.

  In the step B, it is preferable to control the stress at the first 10 cm in order to obtain the effect of the present invention, and it is preferable to control in the range of 100 to 200 N / mm.

  In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the web, and the temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable. By reducing the temperature distribution, it can be expected that the temperature distribution in the width of the web is also reduced.

  In step C, it is preferable to relax in the width direction. Specifically, it is preferable to adjust the web width so that the final web width after stretching in the previous step is in the range of 95 to 99.5%.

  In the present invention, it is also preferable to use a tenter that can independently control the web gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter in order to accurately orient the polymer.

  Specifically, for example, as shown in FIG. 3, as a means for controlling the length of the portion gripping the left and right ends of the web by the tenter stretching device independently to make the grip length of the web different on the left and right. There is something like this.

  FIG. 3 schematically shows an example of a tenter stretching apparatus (10a) that is preferably used in producing the polymer film used in the present invention.

  In the same figure, the grip start position of the left and right grip means (clips) (2a) (2b) of the tenter stretching device (10a) is changed left and right, that is, the installation position of the clip closer (3a) (3b) is changed left and right. By changing the grip start position on the left and right, the left and right grip length of the film (F) is changed, thereby generating a force that twists the resin film (F) in the tenter (10a). Misalignment due to the conveyance can be corrected, and even if the conveyance distance from the peeling to the tenter is increased, the occurrence of meandering, slipping and wrinkling of the web can be effectively prevented.

  Although the illustrated tenter stretching device (10a) is schematically illustrated, it is usually provided in a single row state of a pair of left and right rotation drive devices (ring-shaped chains) (1a) (1b) made of an endless chain. Of the large number of clips (2a) and (2b), the clip (2a) and (2b) of the chain forward straight transition portion that grips and pulls both the left and right ends of the film (F) is the width direction of the film (F) The tracks of the left and right chains (1a) and (1b) are installed so as to be gradually separated from each other, and the film (F) is stretched in the width direction.

  In the present invention, it is preferable to add a device for preventing meandering of a long film in order to correct wrinkles, strains, distortions, etc. with high accuracy, and an edge position controller (EPC) described in JP-A-6-8663. It is preferable to use a meandering correction device such as a center position controller (also referred to as CPC). These devices detect the edge of the film with an air servo sensor or optical sensor and control the transport direction based on that information so that the center of the edge of the film and the width direction is a constant transport position. Specifically, as the actuator, one or two guide rolls or a flat expander roll with drive is applied to the left and right (or up and down) with respect to the line direction to correct meandering, or to the left and right of the film A small pair of two pinch rolls is installed (one on the front and back of the film, and it is on both sides of the film), and the film is sandwiched and pulled to correct meandering. (Cross guider method). The principle of the meandering correction of these devices is that when the film is moving, for example, when going to the left, in the former method, the roll is tilted so that the film goes to the right, and in the latter method, one set on the right side is used. This pinch roll is nipped and pulled to the right. It is preferable to install at least one of these meandering prevention devices between the film peeling point and the tenter stretching device.

  After the treatment in the tenter process, it is preferable to further provide a post-drying process (hereinafter referred to as process D1).

  The web conveyance tension in the step D1 is affected by the physical properties of the dope, at the time of peeling and the residual solvent amount in the step D0, the temperature in the step D1, etc., but is preferably 120 to 200 N / m, preferably 140 to 200 N / m. Further preferred. 140 to 160 N / m is most preferable.

  It is preferable to provide a tension cut roll for the purpose of preventing the web from stretching in the transport direction in step D1.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web drying step is preferably a glass transition point of the film of −5 ° C. or lower, preferably 100 ° C. or higher and 10 minutes or longer and 60 minutes or shorter. Drying is performed at a drying temperature of 100 to 200 ° C, more preferably 110 to 160 ° C. More preferably, heat treatment is carried out while transporting in an atmosphere of 105 to 155 ° C. and an atmosphere substitution rate of 12 times / hour or more, preferably 12 to 45 times / hour.

  In the retardation film of the present invention, the free volume radius determined by the positron annihilation lifetime method is preferably 0.250 to 0.350 nm, particularly 0.250 to It is preferably 0.310 nm.

  The free volume here represents a void portion not occupied by the cellulose resin molecular chain. This can be measured using the positron annihilation lifetime method. Specifically, by measuring the time from the incidence of positrons to the sample until annihilation, non-destructively observing information on the vacancies, the size of free volumes, the number concentration, etc. from the annihilation lifetime Can be sought.

The cellulose ester film of the present invention is produced by the above-described method for producing a cellulose ester film, and the elastic modulus in the slow axis direction in the film plane: εs, and the elastic modulus in the fast axis direction: εf The difference between the following formula (3)
700 ≦ εs−εf ≦ 2450 (3)
It satisfies the relationship.

  Here, the retardation film of the VA type liquid crystal display device is required to have a high retardation value, but the elastic modulus εs and the fast axis direction in the slow axis direction in the film plane of the retardation film made of a cellulose ester film. Difference from the elastic modulus εf of ε: If εs−ε is less than 700, it cannot be achieved. Further, when εs−ε exceeds 2450, it means that the elastic modulus in one direction is lower than that of the other, the film becomes brittle in that direction, the tear strength decreases, and the polarizing plate Since the rework performance at the time of production is significantly deteriorated, it is not preferable.

[Cycloolefin polymer film]
The cycloolefin polymer film preferably used in the present invention will be described.

  The cycloolefin polymer used in the present invention is composed of a polymer resin containing an alicyclic structure.

  A preferred cycloolefin polymer is a resin obtained by polymerizing or copolymerizing a cyclic olefin. Examples of the cyclic olefin include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4. Polycyclic unsaturated hydrocarbons such as 6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclo Examples thereof include monocyclic unsaturated hydrocarbons such as octene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, and derivatives thereof. These cyclic olefins may have a polar group as a substituent. Examples of the polar group include a hydroxyl group, a carboxyl group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group, and a carboxylic acid anhydride group. Or a carboxylic anhydride group is preferred.

  Preferred cycloolefin polymers may be those obtained by addition copolymerization of monomers other than cyclic olefins. Addition copolymerizable monomers include ethylene, propylene, 1-butene, 1-pentene and other ethylene or α-olefins; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl- Examples include dienes such as 1,4-hexadiene and 1,7-octadiene.

The cyclic olefin is obtained by an addition polymerization reaction or a metathesis ring-opening polymerization reaction. The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum Examples thereof include a polymerization catalyst comprising a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of −50 ° C. to 100 ° C. and a polymerization pressure of 0 to 490 N / cm ² .

  The cycloolefin polymer used in the present invention is preferably a polymer obtained by polymerizing or copolymerizing a cyclic olefin, followed by a hydrogenation reaction to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl Homogeneous catalyst consisting of a combination of metal compounds; heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth And a heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

  Or the following norbornene-type polymer is also mentioned as a cycloolefin polymer. The norbornene-based polymer preferably has a norbornene skeleton as a repeating unit. Specific examples thereof include JP-A-62-252406, JP-A-62-2252407, and JP-A-2-133413. JP-A-63-145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815, JP-A-5-39403, JP-A-5-43663 JP-A-5-43834, JP-A-5-70655, JP-A-5-279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, Although what was described in the Kaihei 9-241484 gazette etc. can be utilized preferably, it is not limited to these. Moreover, these may be used individually by 1 type and may use 2 or more types together.

In the present invention, among the norbornene-based polymers, those having a repeating unit represented by any of the following structural formulas (I) to (IV) are preferable.

  In the structural formulas (I) to (IV), A, B, C and D each independently represent a hydrogen atom or a monovalent organic group.

Among the norbornene-based polymers, a polymer obtained by metathesis polymerization of at least one compound represented by the following structural formula (V) or (VI) and an unsaturated cyclic compound copolymerizable therewith. A hydrogenated polymer obtained by hydrogenating is also preferred.

  In the structural formula, A, B, C and D each independently represent a hydrogen atom or a monovalent organic group.

  Here, A, B, C and D are not particularly limited, but preferably an organic group may be linked through a hydrogen atom, a halogen atom, a monovalent organic group, or at least a divalent linking group. These may be the same or different. A or B and C or D may form a monocyclic or polycyclic structure. Here, the at least divalent linking group includes a hetero atom typified by an oxygen atom, a sulfur atom, and a nitrogen atom, and examples thereof include ether, ester, carbonyl, urethane, amide, thioether, and the like. It is not limited. Further, the organic group may be further substituted via the linking group.

  Examples of other monomers copolymerizable with the norbornene-based monomer include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, C2-C20 alpha olefins, such as 1-hexadecene, 1-octadecene, 1-eicocene, and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7 -Cycloolefins such as methano-1H-indene, and derivatives thereof; non 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, etc. Conjugated dienes; and the like are used. Among these, an α-olefin, particularly ethylene is preferable.

  These other monomers copolymerizable with the norbornene-based monomer can be used alone or in combination of two or more. In the case of addition copolymerization of a norbornene monomer and another monomer copolymerizable therewith, the ratio of the structural unit derived from the norbornene monomer and the structural unit derived from the other monomer copolymerizable in the addition copolymer However, it is appropriately selected so that the mass ratio is usually 30:70 to 99: 1, preferably 50:50 to 97: 3, more preferably 70:30 to 95: 5.

  When the unsaturated bond remaining in the molecular chain of the synthesized polymer is saturated by a hydrogenation reaction, the hydrogenation rate is 90% or more, preferably 95% or more, particularly from the viewpoint of light resistance deterioration, weather resistance deterioration, etc. Preferably it is 99% or more.

  In addition, examples of the cycloolefin polymer used in the present invention include thermoplastic saturated norbornene resins described in paragraph Nos. [0014] to [0019] of JP-A No. 5-2108, paragraph No. [0015] of JP-A No. 2001-277430. ] To [0031] thermoplastic norbornene polymers, JP 2003-14901 paragraph Nos. [0008] to [0045] thermoplastic norbornene resins, JP 2003-139950 paragraph Nos. [0014] to [0028] Norbornene-based resin composition, paragraph Nos. [0029] to [0037] described in JP-A No. 2003-161832, paragraph Nos. [0027] to [0036] described in JP-A No. 2003-195268 Norbornene-based resin, JP2003-21158 Paragraph Nos. [0009] to [0023] alicyclic structure-containing polymer resin, norbornene polymer resin or vinyl alicyclic hydrocarbon described in JP-A-2003-212588, paragraph Nos. [0008] to [0024] Polymer resin etc. are mentioned.

  Specifically, ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Co., Ltd., Appel manufactured by Mitsui Chemicals, Inc. (APL8008T, APL6509T, APL6013T, APL5014DP, APL6015T) and the like are preferably used.

  The molecular weight of the cycloolefin polymer used in the present invention is appropriately selected according to the purpose of use, and was measured by a gel permeation chromatography method of a cyclohexane solution (or a toluene solution when the polymer resin does not dissolve). When the polyisoprene or polystyrene-equivalent weight average molecular weight is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000, the mechanical strength and molding processability of the molded body are high. It is preferable to be balanced.

  The cycloolefin polymer film may contain an additive that can be generally blended into a plastic film, if necessary. Examples of such additives include heat stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, and fillers, and the content thereof is within a range that does not impair the purpose of the present invention. You can choose.

  There is no particular limitation on the method for forming the cycloolefin polymer film, and either a hot melt molding method or a solution casting method can be used. The heat-melt molding method can be further classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. Among these methods, mechanical strength, surface accuracy are included. In order to obtain an excellent film, an extrusion molding method, an inflation molding method, and a press molding method are preferable, and an extrusion molding method is most preferable. The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the hot melt molding method, the cylinder temperature is usually in the range of 150 to 400 ° C, preferably 200 to 350 ° C, more preferably 230 to 330 ° C. Is set as appropriate. If the resin temperature is too low, fluidity will deteriorate, causing shrinkage and distortion in the film. If the resin temperature is too high, voids and silver streaks will occur due to thermal decomposition of the resin, and the film will turn yellow. Defects may occur. The thickness of the film is usually in the range of 5 to 300 μm, preferably 10 to 200 μm, more preferably 20 to 100 μm. When the thickness is too thin, handling at the time of stacking becomes difficult, and when it is too thick, the drying time after stacking becomes long and productivity is lowered.

  The cycloolefin polymer film has a surface wetting tension of preferably 40 mN / m or more, more preferably 50 mN / m or more, and even more preferably 55 mN / m or more. When the surface wetting tension is in the above range, the adhesive strength between the film and the polarizing film is improved. In order to adjust the surface wetting tension, for example, corona discharge treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment, and other known surface treatments can be performed.

  The sheet before stretching needs to have a thickness of about 50 to 500 μm, and the thickness unevenness is preferably as small as possible. The entire surface is within ± 8%, preferably within ± 6%, more preferably within ± 4%. is there.

  In order to make the said cycloolefin polymer film into the retardation film of this invention, it can obtain by the manufacturing method similar to the cellulose-ester film mentioned above.

[Polycarbonate film]
There are various types of polycarbonate resins used for preparing polycarbonate films, and aromatic polycarbonates are preferable from the viewpoint of chemical properties and physical properties, and bisphenol A polycarbonates are particularly preferable. Among them, more preferred is a bisphenol A derivative in which a benzene ring, a cyclohexane ring, or an aliphatic hydrocarbon group is introduced into bisphenol A, and these groups are introduced asymmetrically with respect to the central carbon. A polycarbonate having a structure in which the anisotropy in the unit molecule is reduced, obtained by using the obtained derivative is preferable. For example, one in which two methyl groups on the central carbon of bisphenol A are replaced with a benzene ring, and one hydrogen on each benzene ring in bisphenol A is replaced asymmetrically with respect to the central carbon by a methyl group or a phenyl group The polycarbonate obtained is preferred.

  Specifically, 4,4′-dihydroxydiphenylalkane or a halogen-substituted product thereof is obtained by a phosgene method or a transesterification method. For example, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylethane 4,4'-dihydroxydiphenylbutane and the like.

  The retardation film made of the polycarbonate resin used in the present invention may be used by mixing with a transparent resin such as polystyrene resin, methyl methacrylate resin or cellulose acetate resin, or at least one of cellulose acetate films. A polycarbonate resin may be laminated on the surface.

  The polycarbonate film used in the present invention has a glass transition point (Tg) of 110 ° C. or more and a water absorption rate (measured under conditions of 23 ° C. water and 24 hours) of 0.3% or less. It is good to do. More preferably, Tg is 120 ° C. or higher and water absorption is 0.2% or less.

  In order to make the said polycarbonate-type film into the retardation film of this invention, it can obtain by the manufacturing method similar to the cellulose-ester film mentioned above.

  Here, in order to increase the front contrast of the liquid crystal display device, which is the object of the present invention, it is important to minimize the distortion of the polymer constituting the film disposed between the polarizing film and the liquid crystal cell. As described above, in a stretched film, it is necessary to quickly orient the polymer constituting the film and eliminate the cause of light leakage as much as possible, but for the same reason, from the viewpoint of front contrast, The film thickness is also important, and the retardation film of the present invention preferably has a film thickness of 100 μm or less. When the film thickness is increased, not only the above-mentioned factors causing light leakage increase by the film thickness, but in particular, when the film thickness exceeds 100 μm, there is a tendency that light leakage tends to occur due to the increase in film thickness. It can be seen. A preferred film thickness is 80 μm or less, and a more preferred film thickness is 35 to 60 μm.

(Polarizer)
The polarizing plate can be produced by a general method. The back side of the retardation film of the present invention is preferably bonded to at least one surface of a polarizing film prepared by alkali saponification treatment and immersion drawing in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. The film may be used on the other surface, or another polarizing plate protective film may be used. Commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-8, KC8UCR-8 -N, Konica Minolta Opto, Fujitac TD80UF, T80UZ, T40UZ, antireflection film (Fuji Film CV Clearview UA), Fuji Photo Film Co., Ltd.) and the like are preferably used. With respect to the retardation film of the present invention, the polarizing plate protective film used on the other surface is an optically isotropic polarizing plate protection with in-plane retardation Ro of 0 to 20 nm and Rt of -50 to 50 nm. A film is preferred. The polarizing plate protective film preferably has a hard coat layer or an antiglare layer having a thickness of 8 to 20 μm. For example, JP 2003-114333 A, JP 2004-20309 A, and 2004-354699 A , 2004-354828, etc., a polarizing plate protective film having a hard coat layer or an antiglare layer is preferably used. Furthermore, it is preferable that an antireflection layer, an antifouling layer or the like is laminated on the hard coat layer or the antiglare layer.

  Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. By using in combination with the polarizing plate of the present invention, a liquid crystal display device having excellent flatness and a stable viewing angle expansion effect can be obtained.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. On the surface of the polarizing film, one side of the optical film of the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  Ethylene-modified polyvinyl alcohol is also preferably used as the polarizing film. The thickness of the polarizing film is preferably 5 to 30 μm, particularly preferably 10 to 25 μm.

(Display device)
A liquid crystal display device composed of a polarizing plate using the retardation film of the present invention is used to develop a higher display quality than a normal polarizing plate. In particular, the effect of the present invention can be further exerted when used in a multi-domain liquid crystal display device, more preferably in a multi-domain liquid crystal display device by a birefringence mode.

  Multi-domainization is also suitable for improving the symmetry of image display, and various methods have been reported "Okita, Yamauchi: Liquid Crystal, 6 (3), 303 (2002)". The liquid crystal display cell is also shown in “Yamada, Yamabara: Liquid Crystal, 7 (2), 184 (2003)”, but is not limited thereto.

  The polarizing plate of the present invention has an MVA (Multi-domestic Vertical Alignment) mode typified by a vertical alignment mode, in particular, an MVA mode divided into four, a known PVA (Patterned Vertical Alignment) mode multi-domained by electrode arrangement, an electrode It can be effectively used in a CPA (Continuous Pinwheel Alignment) mode in which arrangement and chiral ability are fused. In addition, a proposal of an optically biaxial film is also disclosed in conformity to the OCB (Optical Compensated Bend) mode, and “T. Miyashita, T. Uchida: J. SID, 3 (1), 29 ( 1995) ”, the polarizing plate of the present invention can also exhibit the effect of the present invention in display quality. If the effect of this invention can be expressed by using the polarizing plate of this invention, arrangement | positioning of a liquid crystal mode and a polarizing plate will not be limited. In particular, the retardation film of the present invention is preferably used for a vertical alignment mode liquid crystal display device, and particularly preferably for a MVA (Multi-domein Vertical Alignment) mode liquid crystal display device.

  The display quality of the display cell is preferably symmetrical with respect to human observation. Therefore, when the display cell is a liquid crystal display cell, it is possible to multiplex domains by giving priority to the symmetry on the observation side. A known method can be used to divide the domain, and can be determined in consideration of the properties of a known liquid crystal mode by a two-part dividing method, more preferably a four-part dividing method.

  Liquid crystal display devices are being applied to color display and moving image display devices, and the display quality in the present invention is less fatigued and more faithful to display moving images due to improved contrast and resistance to polarizing plates. It becomes.

  In the liquid crystal display device of the present invention, the polarizing plate using the retardation film of the present invention is disposed only on one surface of the liquid crystal cell or on both surfaces. At this time, it can contribute to improvement of display quality by using the retardation film of the present invention contained in the polarizing plate so as to be on the liquid crystal cell side.

  Examples of the present invention and comparative examples will be described below, but the present invention is not limited to these examples. Note that the present invention is not limited to the solution casting method, and may be applied to, for example, a melt extrusion method.

Example In order to produce a cellulose ester film, five types of cellulose esters A to E shown in Table 1 were prepared.

[Substitution degree of cellulose ester]
These cellulose ester substitution degrees were measured by a saponification method. The dried cellulose ester is precisely weighed and dissolved in a mixed solvent of acetone and dimethyl sulfoxide (volume ratio 4: 1), and then a predetermined 1 mol / L aqueous sodium hydroxide solution is added and saponified at 25 ° C. for 2 hours. Excess sodium hydroxide is titrated with 0.5 mol / L sulfuric acid using phenolphthalein as an indicator. A blank test is performed by the same method as described above. Further, the supernatant of the solution after titration is diluted, and the composition of the organic acid is measured by an ordinary method using an ion chromatograph. Then, the degree of substitution (%) is calculated according to the following.

TA = (Q−P) × F / (1000 × W)
DSac = (162.14 × TA) / (1−42.14 × TA + (1−56.06 × TA) × (AL / AC))
DSpr = DSac × (AL / AC)
In the formula, P is 0.5 mol / L sulfuric acid amount (ml) required for the titration of the sample, Q is 0.5 mol / L sulfuric acid amount (ml) required for the blank test, F is a titer of 0.5 mol / L sulfuric acid, W is the sample mass (g), TA is the total organic acid amount (mol / g), AL / AC is the molar ratio of acetic acid (AC) and other organic acid (AL) measured by ion chromatography, DSac is acetyl The degree of substitution of the group, DSpr, indicates the degree of substitution of the propionyl group (butyryl group).

Example 1
[Preparation of dope]
About the cellulose ester, what changed the substitution degree and the kind of substituent which are shown in Table 1 was used.

  As Example 1, a cellulose ester was blended at the following ratio to prepare a dope.

Cellulose ester A 100 parts by weight Triphenyl phosphate 5.5 parts by weight Ethyl phthalyl ethyl glycolate 5.5 parts by weight Methylene chloride 400 parts by weight Ethanol 45 parts by weight The above cellulose ester blend was placed in an airtight container and mixed. The mixture was heated to 80 ° C. and stirred for 3 hours to completely dissolve. Thereafter, stirring was stopped, the liquid temperature was lowered to 43 ° C., and filtration was performed using a filter paper having a filtration accuracy of 0.005 mm. By allowing this to stand overnight, the bubbles in the dope were degassed.

[Production of optical film]
The dope was adjusted to a dope temperature of 35 ° C. and a support temperature of 25 ° C., and cast from a casting die onto a mirror-treated support belt made of stainless steel. The cellulose ester of Example 1 was released by peeling the web (film) from the support at a peeling residual solvent amount of 80% by weight, and stretching in the width direction of the film while holding both ends of the web with clips using a tenter. A film was prepared. At this time, the stretching ratio Y by the tenter was 30%, the stretching speed X was 5.3 m / min, and the stretching temperature T was 140 ° C. Moreover, the glass transition point Tg of the cellulose ester A at this time was 145 degreeC. The produced cellulose ester film was dried with 120 ° C. drying air.

Examples 2-8
Next, a cellulose ester film is produced in the same manner as in Example 1 above, but the stretching ratio Y is not changed under the conditions shown in Table 2 below without changing the stretching temperature T in the film forming conditions. Various cellulose ester films were prepared by changing the stretching speed X. In addition, as cellulose ester, what changed the substitution degree and the kind of substituent which are shown in the said Table 1 was used.

Comparative Examples 1-5
For comparison, it is carried out in the same manner as in Example 1, except that in Comparative Examples 1 to 3, in the film stretching step, the film stretching speed: X (m / min ) And the draw ratio: Y (%): X × Y is the point where the cellulose ester film was produced under the conditions that are outside the scope of the present invention. In Comparative Examples 4 and 5, cellulose ester films were produced using cellulose ester D and cellulose ester E, in which the total substitution degree of the acyl group of the cellulose ester was outside the scope of the present invention.

Examples 9-12
Next, a cellulose ester film is produced in the same manner as in Example 1, except that only the stretching temperature X (° C.) of the film is changed to the temperature shown in Table 3 below to produce various cellulose ester films. did.

Comparative Examples 6 and 7
For comparison, it is carried out in the same manner as in Example 1 above, but the difference from Example 1 is that in the film stretching step, the film stretching temperature X (° C.) is the temperature shown in Table 3 below. The difference between the glass transition point Tg (° C.) and the stretching temperature T (° C.) is that the cellulose ester film was produced under the condition that Tg-T is outside the scope of the present invention. is there.

  Next, film TD elastic modulus: εs and MD elastic modulus: εf were measured for the various cellulose ester films obtained in Examples 1 to 12 and Comparative Examples 1 to 7.

[Measurement of elastic modulus εs, εf]
The average refractive index of the film sample is measured with an Abbe refractometer, and the elastic moduli εs and εf in the slow axis direction and the direction perpendicular to the slow axis are measured. For example, in the case of a retardation film stretched in the TD direction (width direction), the slow axis is usually the TD direction, and the direction perpendicular to the slow axis is the MD direction (longitudinal direction). In that case, the measurement may be performed according to JIS K 7127 by measuring the elastic modulus of each sample in the MD direction and the TD direction.

  When the slow axis is in the TD direction and the direction perpendicular to the slow axis is in the MD direction, each sample is allowed to stand for 24 hours in an environment of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% RH. The MD direction and the TD direction are each cut into a strip shape having a width of 10 mm and a length of 200 mm so as to be long, and then a chucking pressure of 0.25 MPa using a TG-2KN type tensile tester manufactured by Minibear, The strip sample is set at a distance between marked lines of 100 ± 10 mm, and pulled at a pulling speed of 100 ± 10 mm / min. Then, from the obtained tensile stress-strain curve, the elastic modulus calculation start point is 10 N, the end point is 30 N, and the tangent line drawn therebetween is extrapolated to obtain the elastic modulus in the MD direction and the TD direction.

  About the retardation film produced in the said Examples 1-12 and Comparative Examples 1-7, the measurement result of the obtained elasticity modulus (epsilon) s and (epsilon) f was put together in the following Table 2 and Table 3, and was described.

  Next, a polarizing plate was produced in the following manner using the retardation films produced in Examples 1 to 12 and Comparative Examples 1 to 7, and an evaluation test was performed.

[Preparation of polarizing plate]
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This 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 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizing film.

  Next, the polarizing film and the various retardation films prepared in Examples 1 to 12 and Comparative Examples 1 to 7 according to the following steps 1 to 5 are used as protective films on the front side, and as protective films on the back side. Cellulose ester films (Konica Minolta Tack KV8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) different from the above were laminated to prepare various polarizing plates.

  Step 1: Soaked in a 1 mol / L sodium hydroxide solution at 50 ° C. for 60 seconds, then washed with water and dried to obtain a saponified cellulose ester film bonded to the polarizing film.

  Step 2: The polarizing film was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

  Step 3: Gently wipe off the excess adhesive adhered to the polarizing film in Step 2, place it on the cellulose ester film treated in Step 1, and further stack and arrange so that the antireflection layer is on the outside did.

Step 4: The retardation film, the polarizing film, and the cellulose ester film sample laminated in Step 3 were bonded at a pressure of 20 to 30 N / cm ² and a conveyance speed of about 2 m / min.

  Step 5: In a dryer at 80 ° C., the polarizing film prepared in Step 4, the various retardation films prepared in Examples 1 to 12 and Comparative Examples 1 to 7, and the cellulose ester film are attached. The combined sample was dried for 2 minutes to prepare various polarizing plates.

  Next, the polarizing plate produced using the said retardation film of Examples 1-12 and Comparative Examples 1-7 was integrated in the liquid crystal display device, and the evaluation test was implemented.

[Production of liquid crystal display devices]
The polarizing plate produced by using the retardation films of Examples 1 to 12 and Comparative Examples 1 to 7 above was peeled off from the polarizing plate of a commercially available liquid crystal TV (Aquos 32AD5 manufactured by Sharp). Pasted together. At that time, the direction of bonding of the polarizing plate is such that the surface of the retardation film is on the liquid crystal cell side, and the absorption axis is directed in the same direction as the polarizing plate previously bonded, Various liquid crystal display devices were produced.

[Front contrast evaluation]
In an environment of a temperature of 23 ° C. and a humidity of 55% RH, the backlight of the liquid crystal display device (liquid crystal TV) was turned on and left for 30 minutes to perform measurement.

For the measurement, the front luminance of white display and black display was measured with a liquid crystal TV using EZ-Contrast 160D manufactured by ELDIM, and the ratio was defined as the front contrast. Here, the higher the value, the better the contrast. The obtained evaluation results are summarized in Table 2 and Table 3 below.

  As is clear from the results of Tables 1 and 2, the retardation films of Examples 1 to 12 of the present invention are compared with the retardation films of Comparative Examples 1 to 7, without reducing the display quality, and the front contrast. Is clearly improved.

It is explanatory drawing explaining the extending | stretching angle in a film extending process. It is a schematic plan view which shows an example of the tenter process used for the method of this invention. It is a schematic plan view which shows typically an example of the tenter extending | stretching apparatus used for the method of this invention.

Explanation of symbols

1a: left ring chain (rotary drive)
1b: Right wheel chain (rotary drive)
2a: left clip 2b: right clip 3a: left clip closer 3b: right clip closer 4a: left clip opener 4b: right clip opener 10a: tenter stretching device

Claims (4)

A method for producing a cellulose ester film in which a film end is gripped in a film stretching step, stretched, held, and relaxed in the width direction while being continuously conveyed, and then wound up. The film is stretched in the film stretching step. The product of speed: X (m / min) and draw ratio: Y (%) is the following formula (1)
45 ≦ X × Y ≦ 450 (1)
Here, stretching speed: X means a value obtained by dividing the increment (m) by stretching by the time (min) required for stretching.
A method for producing a cellulose ester film, wherein the film is stretched under a condition satisfying In the film stretching step, the stretching temperature: T (° C.) is the following formula (2) with respect to the glass transition point: Tg (° C.).
1 ≦ Tg−T ≦ 30 (2)
A method for producing a cellulose ester film, wherein the film is stretched under a condition satisfying   The total substitution degree of the acyl group of the cellulose ester to be used is 2.40 to 2.70, and the substitution degree of the acyl group having 3 or more carbon atoms is 0 to 1.1, The manufacturing method of the cellulose-ester film of Claim 1 or 2. It is a cellulose-ester film manufactured with the manufacturing method as described in any one of Claims 1-3, Comprising: The elastic modulus in the slow axis direction in a film surface: (epsilon) s, and the elastic modulus in a fast axis direction : The difference from εf is the following formula (3)
700 ≦ εs−εf ≦ 2450 (3)
A cellulose ester film characterized by satisfying the relationship:

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