JP5373336B2 - Cellulose ester film, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide cellulose ester films useful for liquid crystal display devices, high in moisture stability of retardation in the film thickness direction and excellent in wet heat durability of retardation and dimensional change in the film thickness direction. <P>SOLUTION: The cellulose ester film includes a cellulose ester resin and a polymer X having a weight-average molecular weight of 500-100,000, wherein the polymer X includes at least one monomer unit comprising a phenyl group having 1-4 substituents at ortho or meta position and the polymer X satisfies following formula (1) and formula (2). 30%&le;A&le;100% formula (1). (A indicates the polymerization ratio of a monomer in the polymer X, whose homopolymer has a negative birefringence, when the monomer is polymerized alone). 10%&le;B&le;100% formula (2). (B indicates the polymerization ratio of a monomer in the polymer X, which comprises a phenyl group having 1-4 substituents at ortho or meta position). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a cellulose ester film and a polarizing plate having improved humidity stability and wet heat durability. Specifically, the cellulose ester film useful for a liquid crystal display device having high humidity stability of retardation in the film thickness direction and excellent wet heat resistance of retardation in the film thickness direction and dimensional change was produced using the cellulose ester film. The present invention relates to a polarizing plate and a liquid crystal display device having them.

  In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for the purpose of eliminating image coloring and expanding the viewing angle, and examples thereof include a stretched birefringent film and a film obtained by applying a liquid crystal to a transparent film. For example, Patent Document 1 discloses a technique for applying an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film, aligned, and fixed to a TN mode liquid crystal cell to widen the viewing angle.

  However, a television-use liquid crystal display device that is expected to be viewed from various angles on a large screen has a strict requirement for viewing angle dependency, and even with the above-described method, the requirement cannot be satisfied. Therefore, liquid crystal display devices different from the TN mode, such as an IPS (In-Plane Switching) mode, an OCB (Optically Compensatory Bend) mode, and a VA (Vertically Aligned) mode, have been studied. In particular, the VA mode is becoming mainstream as a liquid crystal display device for TV applications because of its high contrast and relatively high production yield.

  In general, polyvinyl alcohol (hereinafter also referred to as “PVA”) is mainly used as a material of a polarizer essential for a liquid crystal display device. The PVA film is uniaxially stretched and then dyed with iodine or a dichroic dye, or dyed and stretched, and then crosslinked with a boron compound to impart polarization performance and can be used as a polarizer.

  Here, a cellulose ester film is usually used for applications requiring optical isotropy such as a protective film for a polarizing plate. This is based on the fact that the cellulose ester film has a characteristic of high optical isotropy (low retardation value) as compared with other polymer films.

  On the other hand, the optical compensation sheet (retardation film) of the liquid crystal display device is required to have optical anisotropy (high retardation value). Therefore, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film as the optical compensation sheet.

  In other words, the optical member used in the liquid crystal display device uses a synthetic polymer film when the polymer film requires optical anisotropy (high retardation value), and is optically isotropic (low retardation). When value) is required, it was a general principle to use a cellulose ester film.

  Patent Document 2 proposes a cellulose acetate film having a high retardation value that can be used for applications requiring optical anisotropy, overcoming the conventional general principle. In this proposal, in order to realize a high retardation value with cellulose triacetate, an aromatic compound having at least two aromatic rings, particularly a compound having a 1,3,5-triazine ring, is added and subjected to stretching treatment. Cellulose triacetate is generally a polymer material that is difficult to stretch, and it is known that it is difficult to increase the birefringence, but it is necessary to increase the birefringence by simultaneously orienting the additives in the stretching process. To achieve a high retardation value. Since this film can also serve as a protective film for the polarizing plate, there is an advantage that an inexpensive and thin liquid crystal display device can be provided by reducing the number of member films necessary for the liquid crystal display device.

  In recent years, the use of liquid crystal display devices has been expanding, and since there are many uses such as outdoor use and installation in passenger cars, liquid crystal display devices suitable for use in humid heat environments. Is now required. Therefore, there is a demand for a member film that has high humidity stability of retardation in the film thickness direction and excellent resistance to wet heat in the thickness direction retardation and dimensional change.

  On the other hand, as a method for improving the humidity stability of retardation in the film thickness direction, a method of adding an additive or sugar ester having a specific structure (see Patent Document 3), a styrene / p-hydroxystyrene copolymer, etc. A method of adding these additives (see Patent Document 4) has been proposed. In addition, as a method for improving the durability of dimensional change in a long-term use under a wet heat environment, a method of adding a styrene / maleic anhydride copolymer material having negative birefringence has been proposed ( (See Patent Document 5). However, the point of improving the change in optical characteristics with respect to the change in environmental humidity has not been studied in these documents.

Therefore, the development of technology to obtain a film that has sufficiently small changes in optical properties with respect to changes in environmental humidity, has excellent optical properties that affect display performance, and has excellent wet heat durability in dimensional changes, and a polarizing plate using the film. However, the current situation is still strongly desired.
Japanese Patent No. 2587398 European Patent Application No. 91656 International Publication No. 2007/125564 Pamphlet International Publication No. 2007/119646 Pamphlet JP 2007-304376 A

  However, when the present inventors carried out the method of adding these additives described in the above-mentioned literature, the optical characteristics changed with respect to the environmental humidity change, and the long-term in the humid heat environment. It has been found that the durability of the optical properties in use is not satisfactory.

  Therefore, the present inventors have intensively studied, and by adding an additive having a substituent at the ortho group or meta position, in particular environmental humidity compared with the case where an additive having a substituent at the para position is added. It has been found that the change in the optical characteristics can be improved with respect to the change in. That is, the present inventors have invented a film that improves not only the durability of dimensional changes in a humid heat environment but also the humidity stability of the retardation in the film thickness direction and the wet heat durability of the retardation in the film thickness direction.

  An object of the present invention is to use a cellulose ester film useful for a liquid crystal display device excellent in the humidity stability of retardation in the film thickness direction, and in the wet direction heat resistance of retardation in the film thickness direction and dimensional change. It is providing the polarizing plate produced in this way, and a liquid crystal display device which has them.

  As a result of intensive studies, the present inventors have provided the following present invention.

（一般式（１）式中、Ｒ¹〜Ｒ⁷は、各々独立に、水素原子；ハロゲン原子；ヒドロキシル基；カルボキシル基；酸素原子、硫黄原子、窒素原子またはケイ素原子を含む連結基を有していてもよい置換または無置換の炭素数１〜３０の炭化水素基を表す。）
［３］ 前記オルト位またはメタ位に１〜４個の置換基を有するフェニル基を含むモノマー単位が下記一般式（２）または一般式（３）で表される構造であることを特徴とする［１］または［２］に記載のセルロースエステルフィルム。

（一般式（２）および一般式（３）中、Ｒ¹¹およびＲ¹³は各々独立に水素原子またはメチル基を表し、Ｒ¹²およびＲ¹⁴は各々独立に水素原子、炭素数１〜８のアルキル基、または−Ｃ（＝Ｏ）Ｒ¹⁵を表す。前記Ｒ¹⁵は炭素数１〜８のアルキル基を表す。）
［４］ 前記オルト位またはメタ位に１〜４個の置換基を有するフェニル基を含むモノマー単位が下記一般式（４）または一般式（５）で表される構造であることを特徴とする［１］〜［３］のいずれか一項に記載のセルロースエステルフィルム。

（一般式（４）および一般式（５）中、Ｒ²¹およびＲ²²は各々独立に水素原子または−Ｃ（＝Ｏ）−ＣＨ₃基を表す。）
［５］ 下記式（３）を満たすことを特徴とする［１］〜［４］のいずれか一項に記載のセルロースエステルフィルム。
０ ≦ ｜ΔＲｔｈ（１０−８０）｜ ≦ ２０ｎｍ・・・式（３）
（式中、ΔＲｔｈ（１０−８０）は、２５℃相対湿度１０％におけるＲｔｈの値と、２５℃相対湿度８０％におけるＲｔｈの値との差を表す。）
［６］ ６０℃相対湿度９０％で２４時間経過前後におけるＲｔｈの変化量の絶対値ΔＲｔｈ（６０℃９０％ＲＨ）が、１５ｎｍ以下であることを特徴とする請求項１〜５のいずれか一項に記載のセルロースエステルフィルム。
［７］ ６０℃相対湿度９０％で２４時間経過前後におけるセルロースエステルフィルム寸法変化量の絶対値が、０．２％以下であることを特徴とする［１］〜［６］のいずれか一項に記載のセルロースエステルフィルム。
［８］ 前記セルロースエステル樹脂の全置換度（ＤＳ）が、２．３０≦ＤＳ＜２．９８であることを特徴とする［１］〜［７］のいずれか一項に記載のセルロースエステルフィルム。
［９］ レターデーション発現剤を少なくとも一種含有することを特徴とする［１］〜［８］のいずれか一項に記載のセルロースエステルフィルム。
［１０］ ［１］〜［９］のいずれか一項に記載のセルロースエステルフィルムを用いることを特徴とする偏光板。
［１１］ ［１］〜［９］のいずれか一項に記載のセルロースエステルフィルムまたは［１０］に記載の偏光板を用いることを特徴とする液晶表示装置。 [1] Cellulose ester resin and polymer X having a weight average molecular weight of 500 to 100,000 are contained, and polymer X contains at least one monomer unit containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position. And the cellulose-ester film characterized by polymer X satisfy | filling following formula (1) and Formula (2).
30% ≦ A ≦ 100% (1)
(In the formula, A represents a polymerization ratio in the polymer X of a monomer in which the polymer exhibits negative birefringence when polymerized alone.)
10% ≦ B ≦ 100% (2)
(In the formula, B represents a polymerization ratio in the polymer X of a monomer containing a phenyl group having 1 to 4 substituents at the ortho or meta position.)
[2] The monomer unit containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position has a structure represented by the following general formula (1), Cellulose ester film.

(In the general formula (1), R ^{1 to} R ⁷ each independently have a hydrogen atom; a halogen atom; a hydroxyl group; a carboxyl group; an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom-containing linking group. And represents a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms.
[3] The monomer unit containing a phenyl group having 1 to 4 substituents at the ortho-position or the meta-position has a structure represented by the following general formula (2) or general formula (3). The cellulose ester film according to [1] or [2].

(In General Formula (2) and General Formula (3), R ¹¹ and R ¹³ each independently represent a hydrogen atom or a methyl group, and R ¹² and R ¹⁴ each independently represent a hydrogen atom, an alkyl having 1 to 8 carbon atoms. A group or —C (═O) R ¹⁵ , wherein R ¹⁵ represents an alkyl group having 1 to 8 carbon atoms.
[4] The monomer unit containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position has a structure represented by the following general formula (4) or general formula (5). The cellulose ester film according to any one of [1] to [3].

(In General Formula (4) and General Formula (5), R ²¹ and R ²² each independently represent a hydrogen atom or a —C (═O) —CH ₃ group.)
[5] The cellulose ester film according to any one of [1] to [4], wherein the following formula (3) is satisfied.
0 ≦ | ΔRth (10-80) | ≦ 20 nm (3)
(In the formula, ΔRth (10-80) represents the difference between the Rth value at 25 ° C. relative humidity of 10% and the Rth value at 25 ° C. relative humidity of 80%.)
[6] The absolute value [Delta] Rth (60 [deg.] C. 90% RH) of the change amount of Rth before and after 24 hours at 60 [deg.] C. relative humidity 90% is 15 nm or less. The cellulose ester film according to item.
[7] Any one of [1] to [6], wherein an absolute value of a dimensional change amount of the cellulose ester film is about 0.2% or less at a temperature of 60 ° C. and a relative humidity of 90% for about 24 hours. The cellulose ester film described in 1.
[8] The cellulose ester film according to any one of [1] to [7], wherein the total degree of substitution (DS) of the cellulose ester resin is 2.30 ≦ DS <2.98. .
[9] The cellulose ester film according to any one of [1] to [8], which contains at least one retardation developer.
[10] A polarizing plate using the cellulose ester film according to any one of [1] to [9].
[11] A liquid crystal display device using the cellulose ester film according to any one of [1] to [9] or the polarizing plate according to [10].

  The cellulose ester film of the present invention is excellent in the humidity stability of retardation in the film thickness direction, and is useful for a liquid crystal display device excellent in retardation in the film thickness direction and wet heat durability of dimensional change, the cellulose ester film And a liquid crystal display device having them can be produced. In addition, the cellulose ester film of the present invention having such properties, the polarizing plate produced using the cellulose ester film, and the liquid crystal display device having the same undergo a rapid change in humidity under high temperature and high humidity, cooling, or the like. A liquid crystal display device suitably used in an environment can be provided.

  Hereinafter, the cellulose ester film, the polarizing plate and the like of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Further, “*” represents the terminal portion of the repeating unit of the monomer unit.

[Cellulose ester]
The cellulose ester used in the cellulose ester film of the present invention is obtained by substituting the hydroxyl group of the glucose unit constituting the cellulose ester with an acyl group.

  Examples of the cellulose used as a raw material for the cellulose ester used in the present invention include cotton linter and wood pulp (hardwood pulp, softwood pulp). Cellulose esters obtained from any of the raw material cellulose can be used. May be. Detailed descriptions of these raw material celluloses can be found in, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, published by Nikkan Kogyo Shimbun (published in 1970), and the Japan Society of Invention and Innovation Technical Bulletin No. 2001. The cellulose described in No.-1745 (pages 7 to 8) can be used, and the cellulose ester film of the present invention is not particularly limited.

(Cellulose ester)
First, the cellulose ester in which the present invention is preferably used will be described in detail. Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. The cellulose ester is a polymer (polymer) obtained by esterifying some or all of these hydroxyl groups with an acyl group. The degree of acyl substitution means the ratio in which the hydroxyl group of cellulose is esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).

(Degree of substitution)
The total substitution degree DS of the acyl group of the cellulose ester of the present invention is preferably 2.3 ≦ DS ≦ 2.98, more preferably 2.3 ≦ DS ≦ 2.95, and particularly preferably 2.3 ≦. DS ≦ 2.8, most preferably 2.4 ≦ DS ≦ 2.7. Further, if the total substitution degree is in such a range, the compatibility with the cellulose ester resin is improved, and if the compatibility is good, the whitening of the film occurs even when the amount of the polymer X of the present invention is increased. It is difficult to obtain a clear film. In particular, by satisfying 2.3 ≦ DS ≦ 2.98, the wet heat durability of Rth can be greatly improved, and the stability of display performance when used in a liquid crystal display device can be further improved. Further, DS6 / (DS2 + DS3 + DS6) is preferably 0.08 or more, more preferably 0.15 or more, and particularly preferably 0.2 to 0.45. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”). DS6 / (DS2 + DS3 + DS6) is the ratio of the acyl substitution degree at the 6-position to the total acyl substitution degree, and is hereinafter also referred to as “acyl substitution ratio at the 6-position”.

(Acyl group)
Only one type of acyl group may be used in the cellulose ester of the present invention, or two or more types of acyl groups may be used. The cellulose ester film of the present invention preferably has an acyl group having 2 to 4 carbon atoms as a substituent. When two or more kinds of acyl groups are used, one of them is preferably an acetyl group, and the acyl group having 2 to 4 carbon atoms is preferably a propionyl group or a butyryl group in addition to the acetyl group. DSA is the sum of the substitution degrees of the hydroxyl groups at the 2nd, 3rd and 6th positions by the acetyl group, and DSB is the sum of the substitution degrees of the 2nd, 3rd and 6th hydroxyl groups by the propionyl group or butyryl group. The value is preferably 2.3 ≦ DSA + DSB ≦ 2.6, more preferably 2.35 ≦ DSA + DSB ≦ 2.55, and even more preferably 2.4 ≦ DSA + DSB ≦ 2.5. It is preferable that the DSA and DSB values be within the above ranges because a film having a small change in Re value and Rth value due to environmental humidity can be obtained.
Further, 5% or more of DSB is a substituent at the 6-position hydroxyl group, more preferably 10% or more is a substituent at the 6-position hydroxyl group, and more preferably 20% or more is a substituent at the 6-position hydroxyl group. In particular, it is also preferred that 30% or more is a substituent of the 6-position hydroxyl group.

  The acyl group of the cellulose of the present invention may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of these are acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutanoyl group. Group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, an acetyl group, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a tert-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable. A propionyl group and a butanoyl group are most preferred, and an acetyl group is most preferred.

  In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), Basic compounds are used.

  The most common industrial synthesis method of cellulose mixed fatty acid ester is to use cellulose corresponding to fatty acid corresponding to acetyl group and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their anhydrides. This is a method of acylating with a mixed organic acid component.

  The cellulose ester used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

[High molecular weight additive]
The film of this invention contains the high molecular weight additive including the polymer X mentioned later.
The high molecular weight additive used in the film of the present invention has a repeating unit in the compound and preferably has a number average molecular weight of 500 to 100,000. The high molecular weight additive is used for increasing the volatilization rate of the solvent or reducing the residual solvent amount in the solution casting method. Also in a film formed by the melt film forming method, the high molecular weight additive is a useful material for preventing coloring and film strength deterioration. Furthermore, the addition of the high molecular weight additive to the film of the present invention has a useful effect from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. .

Here, the number average molecular weight of the high molecular weight additive in the present invention is more preferably a number average molecular weight of 700 or more and less than 10,000, still more preferably a number average molecular weight of 800 to 8000, still more preferably a number average molecular weight of 800 to 8000. 5000, particularly preferably a number average molecular weight of 1000 to 5000. By setting it as such a range, it is more excellent in compatibility.
Hereinafter, although the high molecular weight additive used for this invention is demonstrated in detail, giving the specific example, it cannot be overemphasized that the high molecular weight additive used by this invention is not necessarily limited to these.

  Of course, the polymer X is included as a polymer additive, and is preferably selected from a polyester polymer, a styrene polymer, an acrylic polymer, and a copolymer thereof, an aliphatic polyester, an aromatic polyester, Acrylic polymers and styrenic polymers are more preferred. Moreover, it is preferable that at least one polymer having negative intrinsic birefringence, such as a styrene polymer and an acrylic polymer, is included.

Polyester polymer The polyester polymer used in the present invention is a mixture of an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and an aromatic dicarboxylic acid having 8 to 20 carbon atoms, an aliphatic diol having 2 to 12 carbon atoms, and a carbon number. It is obtained by a reaction with at least one kind of diol selected from 4-20 alkyl ether diols and C6-C20 aromatic diols, and both ends of the reactants may remain as reactants. Further, the so-called terminal sealing may be carried out by further reacting monocarboxylic acids, monoalcohols or phenols. It is effective in terms of storage stability that the end capping is performed in particular so as not to contain free carboxylic acids. The dicarboxylic acid used in the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms preferably used in the present invention include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid. , Sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.
Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8 -Naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

  Among these, preferable aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acid is phthalic acid. Acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid. Particularly preferably, the aliphatic dicarboxylic acid component is succinic acid, glutaric acid, and adipic acid, and the aromatic dicarboxylic acid is phthalic acid, terephthalic acid, and isophthalic acid.

  In the present invention, at least one of each of the above-mentioned aliphatic dicarboxylic acids and aromatic dicarboxylic acids is used in combination, but the combination is not particularly limited, and there is no problem even if several types of each component are combined.

  Diols or aromatic ring-containing diols used for high molecular weight additives include, for example, aliphatic diols having 2 to 20 carbon atoms, alkyl ether diols having 4 to 20 carbon atoms, and aromatic diols having 6 to 20 carbon atoms. It is chosen from.

  Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols, such as ethane diol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-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. Used as a mixture of two or more.

  Preferred aliphatic diols include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, particularly preferred Is ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

  Preferred examples of the alkyl ether diol having 4 to 20 carbon atoms include polytetramethylene ether glycol, polyethylene ether glycol and polypropylene ether glycol, and combinations thereof. The average degree of polymerization is not particularly limited, but is preferably 2 to 20, more preferably 2 to 10, further 2 to 5, and particularly preferably 2 to 4. As examples of these, commercially useful polyether glycols typically include Carbowax resin, Pluronics resin and Niax resin.

  Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Bisphenol A, 1,4-hydroxybenzene and 1,4-benzenedimethanol are preferred.

In the present invention, a high molecular weight additive whose end is sealed with an alkyl group or an aromatic group is particularly preferable. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the polyester additive of the present invention are not carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples thereof include substituted alcohols such as propanol.

  End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

The synthesis of the high molecular weight additive of the present invention may be carried out by a conventional method, a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the dicarboxylic acid and a diol and / or a monocarboxylic acid or monoalcohol for end-capping. Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. These polyester-based additives are described in detail in Koichi Murai, “Additives, Theory and Application” (Kokaibo Co., Ltd., first edition published on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.
Although the specific example of the polyester-type polymer which can be used by this invention is described below, the polyester-type polymer which can be used by this invention is not limited to these.

表１および表２中、ＰＡはフタル酸を、ＴＰＡはテレフタル酸を、ＩＰＡはイソフタル酸を、ＡＡはアジピン酸を、ＳＡはコハク酸を、２，６−ＮＰＡは２，６−ナフタレンジカルボン酸を、２，８−ＮＰＡは２，８−ナフタレンジカルボン酸を、１，５−ＮＰＡは１，５−ナフタレンジカルボン酸を、１，４−ＮＰＡは１，４−ナフタレンジカルボン酸を、１，８−ＮＰＡは１，８−ナフタレンジカルボン酸をそれぞれ示している。

In Tables 1 and 2, PA is phthalic acid, TPA is terephthalic acid, IPA is isophthalic acid, AA is adipic acid, SA is succinic acid, 2,6-NPA is 2,6-naphthalenedicarboxylic acid 2,8-NPA is 2,8-naphthalenedicarboxylic acid, 1,5-NPA is 1,5-naphthalenedicarboxylic acid, 1,4-NPA is 1,4-naphthalenedicarboxylic acid, 1,8 -NPA represents 1,8-naphthalenedicarboxylic acid, respectively.

[Polymer X]
The polymer X contained in the cellulose ester film of the present invention will be described below.
The polymer X has a weight average molecular weight of 500 to 100,000, and includes monomer units including an aromatic ring having 1 to 4 substituents in at least one ortho position or meta position, and the formula (1) and the formula ( 2) is satisfied.

(Monomer that polymer exhibits negative birefringence when polymerized alone)
The polymerization ratio A in the polymer X of a monomer that exhibits negative birefringence when polymerized alone is 30% ≦ A ≦ 100%, and preferably 40% ≦ A ≦ 100%. If the polymerization ratio (A) is 30% ≦ A ≦ 100%, the polymer X exhibits sufficient negative birefringence, and when added to the cellulose ester film, humidity stability and wet heat durability are improved. Become.

  The monomer that exhibits negative birefringence when polymerized alone will be described in more detail. There is no particular limitation on the monomer that can be used in the present invention and exhibits negative birefringence when polymerized alone. Further, in the polymer X of the present invention, one or a plurality of monomers exhibiting negative birefringence when polymerized alone may be used.

  Examples of the monomer that exhibits negative birefringence when polymerized alone include acrylic monomers, cellulose benzoate monomers, styrene monomers, and ethylenically unsaturated monomers. Among these, acrylic monomers, styrene derived monomers, and vinyl pyrrolidone monomers are preferable, and styrene derived monomers and vinyl pyrrolidone are more preferable from the viewpoint of compatibility.

式中、Ｒ¹⁰¹〜Ｒ¹⁰⁴は、各々独立に、水素原子、ハロゲン原子、酸素原子、硫黄原子、窒素原子またはケイ素原子を含む連結基を有していてもよい、置換もしくは非置換の炭素原子数１〜３０の炭化水素基、または極性基を表し、Ｒ¹⁰⁴は全て同一の原子または基であっても、個々異なる原子または基であっても、互いに結合して、炭素環または複素環(これらの炭素環、複素環は単環構造でもよいし、他の環が縮合して多環構造を形成してもよい)を形成してもよい。
芳香族ビニル系単量体の具体例としては、スチレン；α−メチルスチレン、β−メチルスチレン、ｐ−メチルスチレンなどのアルキル置換スチレン類；４−クロロスチレン、４−ブロモスチレンなどのハロゲン置換スチレン類；ｐ−ヒドロキシスチレン、α−メチル−ｐ−ヒドロキシスチレン、２−メチル−４−ヒドロキシスチレン、３，４−ジヒドロキシスチレンなどのヒドロキシスチレン類；ビニルベンジルアルコール類；ｐ−メトキシスチレン、ｐ−tert−ブトキシスチレン、ｍ−tert−ブトキシスチレンなどのアルコキシ置換スチレン類；３−ビニル安息香酸、４−ビニル安息香酸などのビニル安息香酸類；メチル−４−ビニルベンゾエート、エチル−４−ビニルベンゾエートなどのビニル安息香酸エステル類；４−ビニルベンジルアセテート；４−アセトキシスチレン；２−ブチルアミドスチレン、４−メチルアミドスチレン、ｐ−スルホンアミドスチレンなどのアミドスチレン類；３−アミノスチレン、４−アミノスチレン、２−イソプロペニルアニリン、ビニルベンジルジメチルアミンなどのアミノスチレン類；３−ニトロスチレン、４−ニトロスチレンなどのニトロスチレン類；３−シアノスチレン、４−シアノスチレンなどのシアノスチレン類；ビニルフェニルアセトニトリル；フェニルスチレンなどのアリールスチレン類、インデン類などが挙げられるが、本発明はこれらの具体例に限定されるものではない。これらの単量体は、二種以上を共重合成分として用いてもよい。 The styrene monomer (and styrene derivative monomer) is preferably an aromatic vinyl monomer represented by the general formula (6).

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. R ¹⁰⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ^{104 s} may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.
Specific examples of the aromatic vinyl monomer include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene. P-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene and other hydroxystyrenes; vinyl benzyl alcohols; p-methoxystyrene, p-tert Alkoxy-substituted styrenes such as butoxystyrene and m-tert-butoxystyrene; vinyl benzoic acids such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; vinyl such as methyl-4-vinylbenzoate and ethyl-4-vinylbenzoate Benzoic acid esters; 4-vinylbenzylacetate 4-acetoxystyrene; amidostyrenes such as 2-butylamidostyrene, 4-methylamidostyrene, p-sulfonamidostyrene; 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, vinylbenzyldimethyl Aminostyrenes such as amines; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, indene The present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component.

式中、Ｒ¹⁰⁵〜Ｒ¹⁰⁸は、各々独立に、水素原子、ハロゲン原子、酸素原子、硫黄原子、窒素原子もしくはケイ素原子を含む連結基を有していてもよい、置換もしくは非置換の炭素原子数１〜３０の炭化水素基、または極性基を表す。
当該アクリル酸エステル系単量体の例としては、例えば、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル（ｉ−、ｎ−）、アクリル酸ブチル（ｎ−、ｉ−、ｓ−、tert−）、アクリル酸ペンチル（ｎ−、ｉ−、ｓ−）、アクリル酸ヘキシル（ｎ−、ｉ−）、アクリル酸ヘプチル（ｎ−、ｉ−）、アクリル酸オクチル（ｎ−、ｉ−）、アクリル酸ノニル（ｎ−、ｉ−）、アクリル酸ミリスチル（ｎ−、ｉ−）、アクリル酸（２−エチルヘキシル）、アクリル酸（ε−カプロラクトン）、アクリル酸（２−ヒドロキシエチル）、アクリル酸（２−ヒドロキシプロピル）、アクリル酸（３−ヒドロキシプロピル）、アクリル酸（４−ヒドロキシブチル）、アクリル酸（２−ヒドロキシブチル）、アクリル酸（２−メトキシエチル）、アクリル酸（２−エトキシエチル）アクリル酸フェニル、メタクリル酸フェニル、アクリル酸（２または４−クロロフェニル）、メタクリル酸（２または４−クロロフェニル）、アクリル酸（２または３または４−エトキシカルボニルフェニル）、メタクリル酸（２または３または４−エトキシカルボニルフェニル）、アクリル酸（ｏまたはｍまたはｐ−トリル）、メタクリル酸（ｏまたはｍまたはｐ−トリル）、アクリル酸ベンジル、メタクリル酸ベンジル、アクリル酸フェネチル、メタクリル酸フェネチル、アクリル酸（２−ナフチル）、アクリル酸シクロヘキシル、メタクリル酸シクロヘキシル、アクリル酸（４−メチルシクロヘキシル）、メタクリル酸（４−メチルシクロヘキシル）、アクリル酸（４−エチルシクロヘキシル）、メタクリル酸（４−エチルシクロヘキシル）等、または上記アクリル酸エステルをメタクリル酸エステルに変えたものを挙げることができるが、本発明はこれらの具体例に限定されるものではない。これらの単量体は、２種以上を共重合成分として用いてもよい。これらのうち、工業的に入手が容易で、かつ安価な点で、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル（ｉ−、ｎ−）、アクリル酸ブチル（ｎ−、ｉ−、ｓ−、tert−）、アクリル酸ペンチル（ｎ−、ｉ−、ｓ−）、アクリル酸ヘキシル（ｎ−、ｉ−）、または上記アクリル酸エステルをメタクリル酸エステルに変えたものが好ましい。 The acrylic monomer is preferably an acrylic ester monomer represented by the general formula (7).

In the formula, R ^{105 to} R ¹⁰⁸ each independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. This represents a hydrocarbon group having 1 to 30 or a polar group.
Examples of the acrylate monomer include, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-). , Pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), acrylic acid Nonyl (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2- Hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid Phosphoric acid (2-ethoxyethyl) phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), acrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), Methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, benzyl methacrylate, phenethyl acrylate, Phenethyl methacrylate, acrylic acid (2-naphthyl), cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), methacrylate Although Le acid (4-ethyl cyclohexyl) or the like, or the acrylic acid ester may include those obtained by changing the methacrylic acid esters, the present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component. Of these, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), or those obtained by replacing the above acrylate esters with methacrylate esters are preferred.

式中、Ｒ¹⁰¹〜Ｒ¹⁰⁴は、各々独立に、水素原子、ハロゲン原子、酸素原子、硫黄原子、窒素原子またはケイ素原子を含む連結基を有していてもよい、置換もしくは非置換の炭素原子数１〜３０の炭化水素基、または極性基を表し、Ｒ¹⁰⁴は全て同一の原子または基であっても、個々異なる原子または基であっても、互いに結合して、炭素環または複素環(これらの炭素環、複素環は単環構造でもよいし、他の環が縮合して多環構造を形成してもよい)を形成してもよい。

式中Ｒ¹⁰⁵〜Ｒ¹⁰⁸は、各々独立に、水素原子、ハロゲン原子、酸素原子、硫黄原子、窒素原子もしくはケイ素原子を含む連結基を有していてもよい、置換もしくは非置換の炭素原子数１〜３０の炭化水素基、または極性基を表す。また、共重合組成を構成する上記以外の構造として、前記単量体と共重合性に優れたものであることが好ましく、例として、無水マレイン酸、無水シトラコン酸、シス−１−シクロヘキセン−１，２−無水ジカルボン酸、３−メチル−シス−１−シクロヘキセン−１，２−無水ジカルボン酸、４−メチル−シス−１−シクロヘキセン−１，２−無水ジカルボン酸等の酸無水物、アクリロニトリル、メタクリロニトリルなどのニトリル基含有ラジカル重合性単量体；アクリルアミド、メタクリルアミド、トリフルオロメタンスルホニルアミノエチル（メタ）アクリレートなどのアミド結合含有ラジカル重合性単量体；酢酸ビニルなどの脂肪酸ビニル類；塩化ビニル、塩化ビニリデンなどの塩素含有ラジカル重合性単量体；１，３−ブタジエン、イソプレン、１，４−ジメチルブタジエン等の共役ジオレフィン類をあげることができるが、本発明はこれらに限定されるものではない。この中で特に、スチレン-無水マレイン酸共重合体が特に好ましい。 Further, as the copolymer, those obtained from an aromatic vinyl monomer represented by the general formula (6) and an acrylate ester monomer represented by the general formula (7) are also preferable.

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. R ¹⁰⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ^{104 s} may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.

In the formula, R ^{105 to} R ¹⁰⁸ each independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. 1-30 hydrocarbon groups or a polar group is represented. Further, the structure other than the above constituting the copolymer composition is preferably excellent in copolymerizability with the monomer, and examples thereof include maleic anhydride, citraconic anhydride, cis-1-cyclohexene-1 , 2-dicarboxylic anhydride, 3-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride, 4-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride and the like, acrylonitrile, Nitrile group-containing radical polymerizable monomers such as methacrylonitrile; amide bond-containing radical polymerizable monomers such as acrylamide, methacrylamide, trifluoromethanesulfonylaminoethyl (meth) acrylate; fatty acid vinyls such as vinyl acetate; Chlorine-containing radical polymerizable monomers such as vinyl and vinylidene chloride; 1,3-butadiene, Isoprene, 1,4-dimethyl butadiene and the like can be mentioned conjugated diolefins but the present invention is not limited thereto. Of these, a styrene-maleic anhydride copolymer is particularly preferred.

When the monomer exhibiting negative birefringence when polymerized alone is a styrene-derived monomer, the aromatic ring in the monomer exhibiting negative birefringence when polymerized alone is substituted with a substituent. It is preferable to have. Examples of the substituent include carboxy groups such as alkyl groups, halogen atoms, alkoxy groups, and acetoxy groups, carboxyl groups, amino groups, nitro groups, cyano groups, aryl groups, hydroxyl groups, carbonyl groups, and the like. A carbonyl group or an acetoxy group is preferable, and a hydroxyl group or an acetoxy group is more preferable. In addition, the said substituent may be individual or may be 2 or more. Further, the substituent may or may not further have a substituent.
When the aromatic ring has a substituent, the position of the substituent is not particularly limited, but in the present invention, from the viewpoint of improving the humidity stability of Rth, the aromatic ring is in the ortho position or the meta position. It preferably has a substituent.

The styrene-based monomer may be further condensed with two or more aromatic rings with respect to the aromatic ring, or may be indene or indane in which the substituent forms a ring other than the aromatic ring, A structure having a bridged ring may also be used.
Moreover, although the said aromatic ring may be one or multiple, it is preferable that it is one. Furthermore, it is preferable to have 1 to 4 substituents at the ortho position or meta position of one aromatic ring, more preferably 1 to 2 at the ortho position or meta position. Or it is especially preferable to have one at the meta position.

  When the monomer exhibiting negative birefringence when polymerized alone is not a styrene-derived monomer, it may or may not have a substituent, but particularly a substituent containing an oxygen atom. Is preferably fixed in the cyclic structure so as to be substantially parallel to the main chain of the polymer X from the viewpoint of enhancing the negative birefringence.

  Specific examples of the monomer that exhibits negative birefringence when polymerized alone include styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, etc. Alkyl substituted styrenes; halogen-substituted styrenes such as 2-chlorostyrene and 2-bromostyrene; o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, α-methyl-o-hydroxystyrene, 2-methyl- Hydroxystyrenes such as 3-hydroxystyrene and 2,3-dihydroxystyrene; vinyl benzyl alcohols; alkoxy-substituted styrenes such as o-methoxystyrene, m-tert-butoxystyrene, o-tert-butoxystyrene; 2-vinyl Vinyl such as benzoic acid and 3-vinylbenzoic acid Benzoic acids; vinyl benzoates such as methyl-2-vinylbenzoate and ethyl-2-vinylbenzoate; 2-vinylbenzyl acetate; acetoxystyrenes such as o-acetoxystyrene, m-acetoxystyrene and p-acetoxystyrene Amidostyrenes such as 2-butylamidostyrene, 3-methylamidostyrene, o-sulfonamidostyrene; aminostyrenes such as 2-aminostyrene, 3-aminostyrene, 2-isopropenylaniline, vinylbenzyldimethylamine; Nitrostyrenes such as 2-nitrostyrene and 3-nitrostyrene; cyanostyrenes such as 2-cyanostyrene and 3-cyanostyrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene; Although vinylpyrrolidone etc. are mentioned, this invention is not limited to these specific examples. Among these, styrene, hydroxystyrenes, acetoxystyrenes and vinylpyrrolidone are preferable, and styrene, m-hydroxystyrene, o-hydroxystyrene, m-acetoxystyrene, o-acetoxystyrene and vinylpyrrolidone are more preferable.

(Monomer unit containing a phenyl group having 1 to 4 substituents in the ortho or meta position)
In the present specification, the “phenyl group having 1 to 4 substituents at the ortho-position or meta-position” refers to 1 to 4 of four hydrogen atoms bonded to the ortho-position and meta-position of the phenyl group. Four of them are substituted with a substituent, and the hydrogen atom bonded to the para position means not substituted.

There is no restriction | limiting in particular as a monomer unit containing the phenyl group which has 1-4 substituents in the said ortho position or meta position. In the polymer X of the present invention, the monomer containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position may be used alone or in combination.
The position of the phenyl group in the monomer unit containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position is not particularly limited, and even if the phenyl group is directly connected to the main chain of the monomer unit, The phenyl group may be connected to the main chain through a group. Moreover, there is no restriction | limiting in particular as such a coupling group, For example, an alkylene group etc. can be used.
In addition, a plurality of the phenyl groups may be contained in the monomer unit or may be only one, but preferably one.
The number of substituents of the aromatic ring is 1 to 4, preferably 1 to 3, more preferably 1 or 2, and particularly preferably 1.
Such substituents are not particularly limited. For example, carboxy groups such as alkyl groups, halogen atoms, hydroxyl groups, alkoxy groups, carboxyl groups, acetoxy groups, amide groups, amino groups, nitro groups, cyano groups, sulfo groups. Although a group etc. can be mentioned, this invention is not limited to these specific examples.

  Specific examples of the monomer unit containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position include alkyl-substituted styrenes such as o-methylstyrene and m-methylstyrene; 2-chlorostyrene, 2 Halogen substituted styrenes such as bromostyrene; hydroxystyrenes such as o-hydroxystyrene, m-hydroxystyrene, α-methyl-o-hydroxystyrene, 2-methyl-3-hydroxystyrene, 2,3-dihydroxystyrene; Vinylbenzyl alcohols; alkoxy-substituted styrenes such as o-methoxystyrene, m-tert-butoxystyrene, o-tert-butoxystyrene; vinylbenzoic acids such as 2-vinylbenzoic acid and 3-vinylbenzoic acid; methyl-2 -Vinyl benzoate, ethyl-2-vinyl benzoate Any vinyl benzoates; 2-vinyl benzyl acetate; acetoxy styrenes such as 2-acetoxy styrene and 3-acetoxy styrene; amide styrenes such as 2-butyramide styrene, 3-methylamido styrene and o-sulfonamido styrene Amino styrenes such as 2-aminostyrene, 3-aminostyrene, 2-isopropenylaniline and vinylbenzyldimethylamine; nitrostyrenes such as 2-nitrostyrene and 3-nitrostyrene; 2-cyanostyrene, 3-cyano Examples include cyanostyrenes such as styrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, but the present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component.

  The monomer unit containing an aromatic ring having 1 to 4 substituents at the ortho position or the meta position is preferably a structure represented by the following general formula (1).

（一般式（１）式中、Ｒ¹〜Ｒ⁷は、各々独立に、水素原子；ハロゲン原子；ヒドロキシル基；カルボキシル基；酸素原子、硫黄原子、窒素原子またはケイ素原子を含む連結基を有していてもよい置換または無置換の炭素数１〜３０の炭化水素基を表す。）

(In the general formula (1), R ^{1 to} R ⁷ each independently have a hydrogen atom; a halogen atom; a hydroxyl group; a carboxyl group; an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom-containing linking group. And represents a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms.

In general formula (1), each of R ^{1 to} R ³ independently has a linking group containing a hydrogen atom; a halogen atom; a hydroxyl group; a carboxyl group; an oxygen atom, a sulfur atom, a nitrogen atom, or a silicon atom. Or a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms. R ^{1 to} R ³ are preferably a hydrogen atom or a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. It is a hydrogen group. R ^{1 to} R ³ are more preferably a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms.

R ^{4 to} R ⁷ are each independently a hydrogen atom; a halogen atom; a hydroxyl group; a carboxyl group; a substituted or unsubstituted group which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. A C1-C30 hydrocarbon group is represented. R ^{4 to} R ⁷ are preferably a hydrogen atom; a hydroxyl group; a carboxyl group; a substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms having a linking group containing an oxygen atom. R ^{4 to} R ⁷ are more preferably a hydrogen atom; a hydroxyl group; a carboxyl group; a substituted or unsubstituted group having 1 to 8 carbon atoms in which the linking group is —OC (═O) — or —C (═O). It is a hydrocarbon group.

  The monomer unit containing an aromatic ring having 1 to 4 substituents at the ortho-position or meta-position is more preferably a structure represented by the following general formula (2) or (3).

（一般式（２）および一般式（３）中、Ｒ¹¹およびＲ¹³は各々独立に水素原子またはメチル基を表し、Ｒ¹²およびＲ¹⁴は各々独立に水素原子、炭素数１〜８のアルキル基、または−Ｃ（＝Ｏ）Ｒ¹⁵を表す。前記Ｒ¹⁵は炭素数１〜８のアルキル基を表す。）

(In General Formula (2) and General Formula (3), R ¹¹ and R ¹³ each independently represent a hydrogen atom or a methyl group, and R ¹² and R ¹⁴ each independently represent a hydrogen atom, an alkyl having 1 to 8 carbon atoms. A group or —C (═O) R ¹⁵ , wherein R ¹⁵ represents an alkyl group having 1 to 8 carbon atoms.

In General Formula (2) and General Formula (3), R ¹¹ and R ¹³ each independently represent a hydrogen atom or a methyl group, and preferably a hydrogen atom.
Wherein R ¹² and R ¹⁴ are each independently a hydrogen atom, an alkyl group or -C (= O) R ^15, 1 to 8 carbon atoms, a hydrogen atom or -C (= O) and more to be R ¹⁵ preferable.
R ¹⁵ represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group.

  The monomer unit containing an aromatic ring having 1 to 4 substituents at the ortho or meta position is more preferably a structure represented by the following general formula (4) or (5).

（一般式（４）および一般式（５）中、Ｒ²¹およびＲ²²は各々独立に水素原子または−Ｃ（＝Ｏ）−ＣＨ₃基を表す。）

(In General Formula (4) and General Formula (5), R ²¹ and R ²² each independently represent a hydrogen atom or a —C (═O) —CH ₃ group.)

  By including at least one monomer unit containing a phenyl group having 1 to 4 substituents at the ortho-position or meta-position in the polymer X, the humidity stability of retardation (Rth) in the film thickness direction is greatly improved. . On the other hand, when a monomer unit containing a phenyl group having a substituent only at the para position is used instead of the monomer unit containing a phenyl group having 1 to 4 substituents at the ortho or meta position, the humidity of Rth Stability is hardly improved.

  The monomer containing a phenyl group having 1 to 4 substituents at the ortho-position or meta-position is particularly preferably a monomer that exhibits negative birefringence when polymerized alone.

The polymerization ratio (B) in the polymer X of the monomer containing a phenyl group having 1 to 4 substituents at the ortho position or the meta position is in a range satisfying 10% ≦ B ≦ 100%, and 20% ≦ B ≦ 100% is preferable, and 30% ≦ B ≦ 100% is more preferable.
When the initial polymerization ratio B is 10% ≦ B ≦ 100%, the humidity stability of Rth is remarkably improved and the compatibility with cellulose acetate is also improved.

(Composition of polymer X)
In the present specification, a polymerization ratio (A) of a monomer in which the polymer exhibits negative birefringence when polymerized alone, and a phenyl group having 1 to 4 substituents in the ortho position or the meta position. The polymerization ratio (B) of the monomer to be included can be calculated redundantly. For example, the polymer X is a monopolymer of a monomer containing a phenyl group having 1 to 4 substituents in the ortho position or the meta position when the polymer exhibits a negative birefringence when polymerized alone. May be. In this case, the polymerization ratio A is 100%, and the polymerization ratio B is also 100%. That is, the polymerization ratio A and the polymerization ratio B define the ratio of monomer components having a specific effect in the entire polymer X from two different viewpoints.

As a combination of the polymerization ratio A and the polymerization ratio B, it is more preferable that the polymer X satisfies the following formula (1) and the following formula (2).
30% ≦ A ≦ 100% (1)
10% ≦ B ≦ 100% (2)
Further, the polymer X particularly preferably satisfies the following formulas (4) and (5), and most preferably satisfies the following formulas (6) and (7).
30% ≦ A ≦ 100% ... Formula (4)
20% ≦ B ≦ 100% (5)
50% ≦ A ≦ 100% Formula (6)
20% ≦ B ≦ 100% (7)

  In the polymer X of the present invention, the polymer X is a homopolymer as long as the polymerization ratio A satisfies 30% ≦ A ≦ 100% and the polymerization ratio B satisfies 10% ≦ B ≦ 100%. Alternatively, it may be a copolymer with a monomer containing a phenyl group having 1 to 4 substituents at the ortho or meta position. Furthermore, unless the polymer X of the present invention is contrary to the gist of the present invention, the polymer X is a monomer exhibiting negative birefringence when polymerized alone and 1 to 4 substitutions at the ortho or meta positions. The copolymer containing other monomers other than the monomer containing the phenyl group which has group may be sufficient. Further, when the polymer X is a copolymer, it may be a block copolymer or a random polymer.

  The other monomers are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, alkyl esters of acrylic acid (such as methyl acrylate and ethyl acrylate), alkyl esters of methacrylic acid (such as methyl methacrylate and ethyl methacrylate), and acrylic acid. Aminoalkyl esters (such as diethylaminoethyl acrylate), aminoalkyl esters of methacrylic acid, monoesters of acrylic acid and glycol, monoesters of methacrylic acid and glycol (such as hydroxyethyl methacrylate), alkali metal salts of acrylic acid, methacrylic acid Alkali metal salt of acid, ammonium salt of acrylic acid, ammonium salt of methacrylic acid, quaternary ammonium derivative of aminoalkyl ester of acrylic acid, aminoal of methacrylic acid Quaternary ammonium derivatives of benzene esters, quaternary ammonium compounds of diethylaminoethyl acrylate and methyl sulfate, vinyl methyl ether, vinyl ethyl ether, alkali metal salts of vinyl sulfonic acid, ammonium salts of vinyl sulfonic acid, styrene sulfonic acid, styrene Sulfonate, allyl sulfonic acid, allyl sulfonate, methallyl sulfonic acid, methallyl sulfonate, vinyl acetate, vinyl stearate, N-vinylimidazole, N-vinylacetamide, N-vinylformamide, N-vinylcaprolactam N-vinylcarbazole, acrylamide, methacrylamide, N-alkyl acrylamide, N-methylol acrylamide, N, N-methylenebisacrylamide, glycol diacrylate, group Call dimethacrylate, divinylbenzene, and the like glycol diallyl ether. However, in the present invention, it is preferable to use a monomer having a substituent at the ortho position or the meta position of the phenyl group as the other monomer.

The composition of the polymer X is 1 to 4 substituents at the ortho position or the meta position from the viewpoint of enhancing the Rth humidity stability, Rth wet heat durability and dimensional wet heat durability of the cellulose ester film of the present invention. Or a monomer having a phenyl group having 1 to 4 substituents at the ortho-position or the meta-position, wherein the polymer exhibits negative birefringence when polymerized alone The aspect which consists only of is preferable.
On the other hand, from the viewpoint of increasing the compatibility with the cellulose ester resin, the polymer X may be a copolymer containing the other monomer. When the degree of substitution of the cellulose ester resin is high, the hydrophobicity of the cellulose ester resin is increased. Therefore, it is preferable to improve the compatibility by copolymerizing with other monomers so as to increase the hydrophobicity. On the contrary, when the substitution degree of the cellulose ester resin is low, the hydrophobicity of the cellulose ester resin is lowered. Therefore, it is preferable to improve the compatibility by copolymerizing with other monomers so that the hydrophobicity is lowered. .

  When the polymer X is a homopolymer of a monomer containing a phenyl group having 1 to 4 substituents at the ortho or meta position, the phenyl group having 1 to 4 substituents at the ortho or meta position From the viewpoint of improving the humidity stability of Rth, it is preferable that the monomer containing a hydroxyl group or a carboxyl group. When the polymer X is a homopolymer of a monomer containing a phenyl group having 1 to 4 substituents in the ortho position or the meta position, o-hydroxystyrene, m-acetoxystyrene, o-acetoxystyrene and vinylpyrrolidone A homopolymer is preferred.

  When the polymer X is a copolymer, as a preferable monomer combination, one monomer is styrene, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, o-acetoxystyrene, m-acetoxystyrene, p -At least one of the group consisting of acetoxystyrene and vinylpyrrolidone, and the other monomer may be at least one of the group consisting of o-hydroxystyrene, m-hydroxystyrene, o-acetoxystyrene, m-acetoxystyrene. As a more preferred combination, one monomer is at least one of the group consisting of styrene, o-hydroxystyrene, m-hydroxystyrene, o-acetoxystyrene, m-acetoxystyrene and vinylpyrrolidone, and the other monomer is o- This is the case of at least one member selected from the group consisting of hydroxystyrene, m-hydroxystyrene, o-acetoxystyrene, and m-acetoxystyrene.

(Weight average molecular weight)
The polymer X has a weight average molecular weight of 500 to 100,000. The weight average molecular weight of the polymer X is preferably 700 to 50,000, and more preferably 1,000 to 25,000.
If the molecular weight is 500 or more, the volatility is good, and if the molecular weight is 100,000 or less, the compatibility with the cellulose ester resin is good, both of which are preferable.

(Addition amount)
The amount of the polymer X added is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and 2 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester resin. More preferably. If the addition amount of the polymer X is 30 parts by mass or less, there is an advantage that the expression of retardation can be maintained, and if the addition amount is 1 part by mass or more, there is an advantage that the wet heat durability improving effect is great.

[Low molecular weight additive]
Examples of the low molecular weight additive include a retardation developing agent, a retardation developing agent, a deterioration preventing agent, an ultraviolet preventing agent, a peeling accelerator, other plasticizers, and an infrared absorbing agent. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the cellulose acylate solution (dope) preparation step, but it may be added by adding a preparation step to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested.

(Retardation expression agent)
In the present invention, since a retardation value is expressed, it is preferable to use a retardation developer. Examples of the retardation enhancer that can be used in the present invention include those composed of rod-shaped or discotic compounds. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer.
The addition amount of the retardation developer composed of the rod-like compound is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose ester. preferable.
The discotic retardation developer is preferably used in the range of 0.05 to 20 parts by mass, and preferably in the range of 1.0 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester resin. More preferably, it is more preferably used in the range of 3.0 to 10 parts by mass.
Since the discotic compound is superior to the rod-shaped compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. 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 the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly 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 ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent.
Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (for example, a hydroxy group, a carboxy group, an alkoxy group, an alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- Each group of a diethylaminoethyl group is included.
The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.
The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer is preferably 300 to 800.

  As the discotic compound, a triazine compound represented by the following general formula (I) is preferably used.

In the above general formula (I):
R ⁵¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.
X ¹¹ each independently represents a single bond or —NR ⁵² —. Here, each R ⁵² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ⁵¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ⁵¹ may have at least one substituent at any substitution position. Examples of the substituent include halogen atom, hydroxyl group, cyano group, nitro group, carboxyl group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by R ⁵¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ¹¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below.

The alkyl group represented by R ⁵² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ⁵² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group, and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ⁵² are the same as the aromatic ring and heterocyclic ring represented by R ¹² , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ⁵¹ .

  As the discotic compound, a triphenylene compound represented by the following general formula (II) can also be preferably used.

In the general formula (II), R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a hydrogen atom or a substituent.
As the substituents represented by R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ , an alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably carbon number). 1-20 alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc. ), An alkenyl group (preferably an alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a vinyl group, an allyl group, 2- Butenyl group, 3-pentenyl group and the like), alkynyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 2 carbon atoms). 20 alkynyl groups such as propargyl group and 3-pentynyl group) and aryl groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). For example, a phenyl group, a p-methylphenyl group, a naphthyl group, and the like, a substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, Particularly preferred is an amino group having 0 to 20 carbon atoms, and examples thereof include an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group).

An alkoxy group (preferably an alkoxy group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group). Aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group. An acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms, such as an acetyl group, a benzoyl group, a formyl group, and a pivaloyl group. Etc.), an alkoxycarbonyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably carbon number) To 20 alkoxy groups such as methoxycarbonyl group and ethoxycarbonyl group), aryloxycarbonyl groups (preferably having 7 to 40 carbon atoms, more preferably having 7 to 30 carbon atoms, and particularly preferably carbon atoms). An aryloxycarbonyl group having 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 carbon atoms). ˜20 acyloxy groups such as an acetoxy group and a benzoyloxy group)

An acylamino group (preferably an acylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as an acetylamino group and a benzoylamino group), alkoxycarbonyl An amino group (preferably an alkoxycarbonylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonylamino group), aryloxy Carbonylamino group (preferably an aryloxycarbonylamino group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonylamino group) Sulfonylamino group (preferably having 1 to 40 carbon atoms, more preferred Or a sulfonylamino group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfonylamino group and a benzenesulfonylamino group, and a sulfamoyl group (preferably having a carbon number of 0 to 40). More preferably, it is a sulfamoyl group having 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group. ), A carbamoyl group (preferably a carbamoyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, an unsubstituted carbamoyl group, a methylcarbamoyl group, diethylcarbamoyl group Group, phenylcarbamoyl group, etc.),

Alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group , Heptylthio group, octylthio group and the like), arylthio group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, phenylthio group). ), A sulfonyl group (preferably a sulfonyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a mesyl group and a tosyl group), sulfinyl Group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 2 carbon atoms) Sulfinyl group, for example, methanesulfinyl group, benzenesulfinyl group, etc.), ureido group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms). A ureido group, for example, an unsubstituted ureido group, a methylureido group, a phenylureido group, and the like, a phosphoric acid amide group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably Is a phosphoric acid amide group having 1 to 20 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, a chlorine atom, bromine). Atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group A hydrazino group, an imino group, a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, for example, a heterocyclic group having a heteroatom such as a nitrogen atom, oxygen atom, sulfur atom, etc. And examples thereof include imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, and 1,3,5-triazyl group). Silyl group (preferably a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group) Is included. These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituents represented by R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ are each preferably an alkyl group, aryl group, substituted or unsubstituted amino group, alkoxy group, alkylthio group or halogen atom. is there.

Although the specific example of a compound represented by general formula (II) below is given, it is not limited to these.

  The compound represented by general formula (I) is, for example, the method described in JP-A No. 2003-344655, and the compound represented by general formula (II) is, for example, the method described in JP-A-2005-134484. Can be synthesized by a known method.

  In the present invention, rod-like compounds having a linear molecular structure can be preferably used in addition to the above-mentioned discotic compounds. 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 can be performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (III) is preferable.

Formula (III): Ar ¹ -L ¹¹ -Ar ²

In the general formula (III), Ar ¹ and Ar ² 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.
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 the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethyl group) Each group of tilureido group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) Pentyloxy group, heptyloxy group, octyloxy group), arylo Si group (for example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group ( For example, phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfo group) Group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group ( For example, a morpholyl group and a pyrazinyl group) are included.

Among these, preferred substituents include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.
The alkyl part and the alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, An alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (III), L ¹¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and a combination thereof.
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, and most preferably 1-6. It is.

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 alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (III), the angle formed by Ar ¹ and Ar ² across L ¹¹ is preferably 140 degrees or more.

As the rod-like compound, a compound represented by the following formula (IV) is more preferable.
Formula (IV): Ar ¹ -L ¹² -XL ¹³ -Ar ²

In the general formula (IV), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (III).

In the general formula (IV), L ¹² and L ¹³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination 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 alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or ethylene group).
L ¹² and L ¹³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (IV), X is a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

  Specific examples of the compound represented by the general formula (III) or (IV) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized with reference to methods described in literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

Moreover, you may use the rod-shaped aromatic compound of pages 11-14 of Unexamined-Japanese-Patent No. 2004-50516 as said Re expression agent.
Further, as the Re enhancer, one kind of compound can be used alone, or two or more kinds of compounds can be mixed and used. It is preferable to use two or more compounds different from each other as the Re enhancer because the retardation adjustment range is widened and can be easily adjusted to a desired range.
The addition amount of the Re enhancer is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass with respect to 100 parts by mass of cellulose acylate. When the cellulose acylate film is produced by a solvent cast method, the Re enhancer may be added to the dope. The addition may be performed at any timing. For example, the Re developing agent may be dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, etc., and then added to the cellulose acylate solution (dope) or directly. You may add during dope composition.

  In particular, the ratio of the discotic compound is preferably 10% to 90%, more preferably 20% to 80%, based on the total mass of the discotic compound and the rod-shaped compound.

  In addition, specific examples of preferable compounds of rod-like compounds other than those described in the above-mentioned publications are shown below.

  The specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.
Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.
In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

（式中、Ｒ⁶¹はアルキル基またはアリール基を表し、Ｒ⁶²およびＲ⁶³は、それぞれ独立に、水素原子、アルキル基またはアリール基を表す。Ｒ⁶¹、Ｒ⁶²およびＲ⁶³の炭素原子数の総和は１０以上である。）

（式中、Ｒ⁶⁴およびＲ⁶⁵は、それぞれ独立に、アルキル基またはアリール基を表す。Ｒ⁶⁴およびＲ⁶⁵の炭素原子数の総和は１０以上である。） (Retardation reducing agent)
The optical film of the present invention may contain a retardation reducing agent.
Although it does not specifically limit as a retardation reducing agent, The compound represented by General formula (8)-(12-4) described below is mentioned.

(In the formula, R ⁶¹ represents an alkyl group or an aryl group, and R ⁶² and R ⁶³ each independently represents a hydrogen atom, an alkyl group or an aryl group. The number of carbon atoms of R ⁶¹ , R ⁶² and R ⁶³ is The sum is 10 or more.)

(In the formula, R ⁶⁴ and R ⁶⁵ each independently represents an alkyl group or an aryl group. The total number of carbon atoms of R ⁶⁴ and R ⁶⁵ is 10 or more.)

In the general formula (8), R ⁶¹ represents an alkyl group or an aryl group, and R ⁶² and R ⁶³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Moreover, it is particularly preferable that the total number of carbon atoms of R ⁶¹ , R ⁶² and R ⁶³ is 10 or more. In the general formula (5), R ⁶⁴ and R ⁶⁵ each independently represents an alkyl group or an aryl group. The total number of carbon atoms of R ⁴ and R ⁵ is 10 or more, and each of the alkyl group and aryl group may have a substituent. As the substituent, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are particularly preferable. The alkyl group may be linear, branched, or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and 6 to 20 ( For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, amyl group, isoamyl group, tert-amyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, bicyclooctyl Group, nonyl group, adamantyl group, decyl group, tert-octyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, didecyl group). As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl group, biphenyl group, terphenyl group, naphthyl group, binaphthyl group, triphenylphenyl group) are particularly preferable. Although the preferable example of a compound represented by General formula (8) or General formula (9) is shown below, this invention is not limited to these specific examples.

The compound represented by the general formula (8) or the general formula (9) can be prepared by the following method.
The compound of the general formula (8) can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative. The compound of the general formula (9) can be obtained by oxidation reaction of sulfide or Friedel-Crafts reaction of aromatic compound and sulfonic acid chloride.

Next, the compound represented by the general formula (10) will be described in detail.

In the above general formula (10), R ⁷¹ represents an aryl group. R ⁷² and R ⁷³ each independently represents an alkyl group or an aryl group, and at least one of them is an aryl group. When R ⁷² is an aryl group, R ⁷³ may be an alkyl group or an aryl group, but more preferably an alkyl group. Here, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and 1 to 12 carbon atoms. Is most preferred. The aryl group preferably has 6 to 36 carbon atoms, and more preferably 6 to 24 carbon atoms.

Next, the compound represented by the general formula (11) will be described in detail.

In the general formula (11), R ⁸¹ , R ⁸² and R ⁸³ each independently represents an alkyl group. Here, the alkyl group may be linear, branched or cyclic. R ⁸¹ is preferably a cyclic alkyl group, and at least one of R ⁸² and R ⁸³ is more preferably a cyclic alkyl group. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 12 carbon atoms. As the cyclic alkyl group, a cyclohexyl group is particularly preferable.

  The alkyl group and aryl group in the general formulas (10) and (11) may each have a substituent. Substituents include halogen atoms (for example, chlorine, bromine, fluorine and iodine), alkyl groups, aryl groups, alkoxy groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, sulfonylamino groups, A hydroxy group, a cyano group, an amino group and an acylamino group are preferred, more preferably a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a sulfonylamino group and an acylamino group, and particularly preferably an alkyl group and an aryl group. A sulfonylamino group and an acylamino group.

  Next, although the preferable example of a compound represented by General formula (10) and (11) is shown below, this invention is not limited to these specific examples.

Next, the compound represented by the general formula (12) will be described.

In the general formula (12), R ³¹ , R ³² , R ³³ and R ³⁴ each represent a hydrogen atom, a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group, and an aliphatic group Is preferred. The aliphatic group may be linear, branched or cyclic, and more preferably cyclic. Examples of the substituent that the aliphatic group and the aromatic group may have include the substituent T described later, but an unsubstituted one is preferable.

X ³¹ , X ³² , X ³³ and X ³⁴ are each a single bond, —CO— and NR ³⁵ — (R ³⁵ represents a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group; It represents a divalent linking group formed from one or more groups selected from the group consisting of unsubstituted and / or aliphatic groups. The combination of X ³¹ , X ³² , X ³³ and X ³⁴ is not particularly limited, but is more preferably selected from —CO— and —NR ³⁵ —. a, b, c and d are integers of 0 or more, preferably 0 or 1, a + b + c + d is 2 or more, preferably 2 to 8, more preferably 2 to 6, still more preferably 2-4. Z ³¹ represents an (a + b + c + d) -valent organic group (excluding a cyclic group). The valence of Z ³¹ is preferably 2 to 8, more preferably 2 to 6, further preferably 2 to 4, and most preferably 2 or 3. An organic group refers to a group composed of an organic compound.

The general formula (12) is preferably a compound represented by the following general formula (12-1).
Formula (12-1)
R ³¹¹ -X ³¹¹ -Z ³¹¹ -X ³¹² -R ³¹²

In the general formula (12-1), R ³¹¹ and R ³¹² each represents a substituted or unsubstituted aliphatic group or a substituted or unsubstituted aromatic group, and an aliphatic group is preferable. The aliphatic group may be linear, branched or cyclic, and more preferably cyclic. Examples of the substituent that the aliphatic group and the aromatic group may have include the substituent T described later, but an unsubstituted one is preferable. X ³¹¹ and X ³¹² each independently represent —CONR ³¹³ — or NR ³¹⁴ CO—, and R ³¹³ and R ^{314 each} represents a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group. More preferred are unsubstituted and / or aliphatic groups. Z ³¹¹ is —O—, —S—, —SO—, —SO ₂ —, —CO—, —NR ³¹⁵ — (R ³¹⁵ is a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group. Represents an unsubstituted group and / or an aliphatic group, and a divalent organic group (excluding a cyclic group) formed from one or more groups selected from an alkylene group and an arylene group. . The combination of Z ³¹¹ is not particularly limited, but is preferably selected from —O—, —S—, —NR ³¹⁵ —, and an alkylene group, more preferably selected from —O—, —S—, and an alkylene group. Most preferably, it is selected from, -O-, -S- and an alkylene group.

The general formula (12-1) is preferably a compound represented by the following general formulas (12-2) to (12-4).

In the general formulas (12-2) to (12-4), R ³²¹ , R ³²² , R ³²³ and R ³²⁴ each represents a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group. An aliphatic group is preferred. The aliphatic group may be linear, branched or cyclic, and more preferably cyclic. Examples of the substituent that the aliphatic group and the aromatic group may have include the substituent T described later, but an unsubstituted one is preferable. Z ³²¹ is —O—, —S—, —SO—, —SO ₂ —, —CO—, —NR ³²⁵ — (R ³²⁵ is a substituted or unsubstituted aliphatic group, or a substituted or unsubstituted aromatic group. Represents an unsubstituted group and / or an aliphatic group, and a divalent linking group formed from one or more groups selected from an alkylene group and an arylene group. The combination of Z ³²¹ is not particularly limited, but is preferably selected from —O—, —S—, —NR ³²⁵ —, and an alkylene group, more preferably selected from —O—, —S—, and an alkylene group. Most preferably, it is selected from, -O-, -S- and an alkylene group.

  Hereinafter, the substituted or unsubstituted aliphatic group will be described. The aliphatic group may be linear, branched or cyclic, preferably having 1 to 25 carbon atoms, more preferably having 6 to 25 carbon atoms, particularly preferably having 6 to 20 carbon atoms. preferable. Specific examples of the aliphatic group include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group, tert-butyl group, amyl group, isoamyl group, tert- Amyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, bicyclooctyl group, adamantyl group, n-decyl group, tert-octyl group, dodecyl group, hexadecyl group, octadecyl group, didecyl group, etc. Is mentioned.

Below, said aromatic group is demonstrated.
The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group. The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, and more preferably 6 to 12 carbon atoms. Specific examples of the aromatic hydrocarbon group include benzene, naphthalene, anthracene, biphenyl, terphenyl, and the like. As the aromatic hydrocarbon group, benzene, naphthalene, and biphenyl are particularly preferable. As the aromatic heterocyclic group, those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferable. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, Examples include isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. As the aromatic heterocyclic group, pyridine, triazine, and quinoline are particularly preferable.

Moreover, the said substituent T is demonstrated in detail below.
Examples of the substituent T include alkyl groups (preferably those having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms such as methyl group, ethyl group, isopropyl group, tert-butyl group. , N-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2). For example, vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably having 2-20 carbon atoms, more preferably 2-12 carbon atoms, particularly preferably 2-8 carbon atoms). Yes, for example, propargyl group, 3-pentynyl group, etc., aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 and particularly preferably 6 to 1). 2, for example, phenyl group, biphenyl group, naphthyl group, etc.), amino group (preferably 0-20 carbon atoms, more preferably 0-10, particularly preferably 0-6, for example amino group, methylamino group , A dimethylamino group, a diethylamino group, a dibenzylamino group, etc.), an alkoxy group (preferably having a carbon number of 1-20, more preferably 1-12, particularly preferably 1-8, such as methoxy group, ethoxy group, butoxy Group), an aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms such as a phenyloxy group and a 2-naphthyloxy group), an acyl group (preferably C1-C20, More preferably, it is 1-16, Most preferably, it is 1-12, for example, an acetyl group, a benzoyl group, a formyl group, A valoyl group), an alkoxycarbonyl group (preferably having a carbon number of 2-20, more preferably 2-16, particularly preferably 2-12, such as a methoxycarbonyl group, an ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as a phenyloxycarbonyl group, an acyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly Preferably they are 2-10, for example, an acetoxy group, a benzoyloxy group, etc., an acylamino group (preferably C2-C20, More preferably, it is 2-16, Most preferably, it is 2-10, for example, an acetylamino group, A benzoylamino group), an alkoxycarbonylamino group (preferably having a carbon number of 2 0, more preferably 2 to 16, particularly preferably 2 to 12, for example, methoxycarbonylamino group, etc., aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7-12, such as phenyloxycarbonylamino group, sulfonylamino group (preferably 1-20 carbon atoms, more preferably 1-16, particularly preferably 1-12, such as methanesulfonylamino group, benzene Sulfonylamino groups),

Sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms such as sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl group, etc.) A carbamoyl group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, etc.), an alkylthio group (preferably Has 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methylthio group and an ethylthio group, and an arylthio group (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, Particularly preferred is 6 to 12, for example, phenylthio group), sulfoni Group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as mesyl group and tosyl group), sulfinyl group (preferably having 1 to 20 carbon atoms, More preferably, it is 1-16, Most preferably, it is 1-12, for example, a methanesulfinyl group, a benzenesulfinyl group, etc., a ureido group (preferably 1-20 carbon atoms, more preferably 1-16, particularly preferably 1-1). 12, for example, ureido group, methylureido group, phenylureido group, etc.), phosphoric acid amide group (preferably 1-20 carbon atoms, more preferably 1-16, particularly preferably 1-12, such as diethyl phosphorus Acid amide, phenylphosphoric acid amide, etc.), hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine) A cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, and a heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms). As the hetero atom, for example, nitrogen atom, oxygen atom, sulfur atom, specifically, for example, imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl Groups, benzthiazolyl groups, etc.), silyl groups (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms such as trimethylsilyl group and triphenylsilyl group). . These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

Preferred examples of the compound represented by the general formula (12) are shown below, but the present invention is not limited to these specific examples.

  The compounds of general formula (10), general formula (11), and general formula (12) are obtained by dehydration condensation reaction of carboxylic acids with amines using a condensing agent (for example, dicyclohexylcarbodiimide (DCC)), or carboxylic acid It can be obtained by a substitution reaction between a chloride derivative and an amine derivative.

The retardation reducing agent is preferably added at a rate of 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, more preferably 0.1 to 10%, based on the cellulose resin. It is particularly preferable to add at a ratio of mass%.
By making the said addition amount 30 mass% or less, compatibility with a cellulose resin can be improved and whitening can be suppressed. When using two or more types of retardation reducing agents, the total amount is preferably within the above range.

(Other additives)
The cellulose ester film of the present invention may have other additives in addition to the high molecular weight additive, the polymer X, the retardation developer, and the retardation reducing agent. Examples of other additives include deterioration inhibitors, ultraviolet absorbers, peeling accelerators, plasticizers, and the like.

(Antioxidant)
In the present invention, a known antioxidant for the cellulose ester solution such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-methylphenol) is used. 1, 1′-bis (4-hydroxyphenyl) cyclohexane, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythrityl-tetrakis [ Phenolic or hydroquinone antioxidants such as 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The added amount of the antioxidant is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(UV absorber)
In the present invention, an ultraviolet absorber is preferably used for the cellulose ester solution from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. 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 ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5 -Chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The added amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm by mass in the whole cellulose ester film.

(Peeling accelerator)
The film of the present invention may contain a peeling accelerator. A peeling accelerator can be included in the ratio of 0.001-1 mass%, for example. As the peeling accelerator, known ones can be employed, and examples thereof include citric acid ethyl esters.

(Plasticizer)
A plasticizer can be added to the film of the present invention in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP), biphenyl diphenyl phosphate (BDP), and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. A mixture of TPP and BDP in a ratio of 1: 1 is particularly preferable. The addition amount of the plasticizer is preferably 0.1 to 25% by mass, more preferably 1 to 20% by mass, based on the mass of the cellulosic resin.
In the present invention, as the plasticizer, in addition to these low molecular weight additives, polyester polymers exemplified as the high molecular weight additive are also preferably used as the plasticizer.

[Cellulose ester film]
The cellulose ester film of the present invention comprises a cellulose ester resin having an acyl substitution degree of 2.3 or more and at least one polymer X.

  In addition, the cellulose ester film of the present invention may be a single layer or a plurality of layers. For example, when the cellulose ester film of the present invention is produced by co-casting, it may be composed of two or more layers of a core layer and a skin layer. At this time, the polymer X may be included in either the core layer or the skin layer, but is preferably included in the core layer.

(Average moisture content)
In the cellulose ester film of the present invention, the equilibrium water content at 25 ° C. and relative humidity 60% is preferably 10% or less, more preferably 5% or less, and particularly preferably 3% or less. By setting the average moisture content to 10% or less, it is easy to cope with humidity changes, and it is preferable that optical characteristics and dimensions are more difficult to change.

(Retardation)
In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the film thickness direction at wavelength λ. In the present specification, the wavelength λ is 590 nm unless otherwise specified. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis) (in the absence of the slow axis, any direction in the film plane) Is measured in 6 points from the inclined direction in 10 degree steps from the normal direction to 50 degrees on one side with respect to the normal direction of the film. KOBRA 21ADH calculates based on the retardation value, the assumed average refractive index, and the input film thickness value. The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated from the following equations (11) and (12) based on the assumed average refractive index and the input film thickness value. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose ester (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

Here, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. d represents the film thickness.
Rth = ((nx + ny) / 2−nz) × d (12)
At this time, an average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (“Abbe refractometer 2-T” manufactured by Atago Co., Ltd.) was used.

The preferred range of the retardation value of the cellulose ester film varies depending on the application. Rth of the cellulose ester film of the present invention is preferably 40 nm ≦ Rth <300 nm, more preferably 50 nm <Rth <280 nm, and particularly preferably 80 nm <Rth <250 nm.
The Re is preferably 0 nm <Re <100 nm, more preferably 20 nm <Re <80 nm, and particularly preferably 30 nm <Re <70 nm.

(Rth humidity stability)
The cellulose ester film of the present invention has a small change in optical properties when the humidity changes. By reducing the humidity dependence of the optical properties in this way, a high degree of retardation at the same level as normal temperature can be exhibited even under high humidity, and a cellulose ester film suitable for use under high humidity is obtained. be able to.
The cellulose ester film of the present invention preferably satisfies the following formula (3).
0 ≦ | ΔRth (10-80) | ≦ 20 nm (3)
(In the formula, ΔRth (10-80) represents the difference between the Rth value at 25 ° C. relative humidity of 10% and the Rth value at 25 ° C. relative humidity of 80%.)
Furthermore, it is more preferable that the cellulose ester film of the present invention satisfies the following formula (8).
0 ≦ | ΔRth (10-80) | ≦ 15 nm Formula (8)
(In the formula, ΔRth (10-80) represents the difference between the Rth value at 25 ° C. relative humidity of 10% and the Rth value at 25 ° C. relative humidity of 80%.)

(Rth wet heat durability)
The cellulose ester film of the present invention has a small change in optical properties when stored for a long time under high temperature and high humidity. Thus, by improving the wet heat durability of the optical properties, it is possible to exhibit high retardation for a long time even under high temperature and high humidity, and to obtain a cellulose ester film suitable for use under high temperature and high humidity. Can do.
In the cellulose ester film of the present invention, the absolute value ΔRth (60 ° C. and 90% RH) of the change in Rth before and after 24 hours at 60 ° C. and 90% relative humidity is preferably 20 nm or less, and preferably 15 nm or less. More preferably, it is 10 nm or less.

(Resistance to changes in wet heat)
The cellulose ester film of the present invention has a small dimensional change when stored for a long time under high temperature and high humidity. Thus, the cellulose-ester film suitable also for use under high temperature and high humidity can be obtained by improving the wet heat durability of a dimensional change.
The absolute value of the dimensional change of the cellulose ester film before and after 24 hours at 60 ° C. and 90% relative humidity of the cellulose ester film of the present invention is preferably 0.4% or less, and preferably 0.2% or less. preferable.

(Film thickness)
The film thickness of the cellulose ester film of the present invention is preferably 20 to 80 μm, more preferably 30 to 70 μm, still more preferably 35 to 55 μm. By setting it to 20 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 80 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.

[Method for producing cellulose ester film]
The film of the present invention can be widely used for producing a known cellulose ester film, and is preferably produced by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) in which cellulose ester is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.

Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

A cellulose ester solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent.
The quantity of a cellulose ester is adjusted so that it may be contained in 10-40 mass% in the solution obtained. The amount of the cellulose ester is more preferably 10 to 30% by mass. In the organic solvent (main solvent), the polymer X and the above-mentioned optional additives can be added.
The solution can be prepared by stirring the cellulose ester and the organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, the cellulose ester and the organic solvent are placed in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, the cellulose ester can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose ester with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.
In the cooling dissolution method, first, a cellulose ester is gradually added to an organic solvent with stirring at room temperature. The amount of the cellulose ester is preferably adjusted so that it is contained in the mixture in an amount of 10 to 40% by mass. The amount of the cellulose ester is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.
The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this manner, the mixture of cellulose ester and organic solvent solidifies.

The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.
Further, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), the cellulose ester is dissolved in the organic solvent. The temperature can be raised by simply leaving it at room temperature or in a warm bath. The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and most preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. .

A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.
In the cooling dissolution method, it is desirable to use a sealed container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container.
In addition, according to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose ester (total acetyl substitution degree: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by the cooling dissolution method is There is a quasi-phase transition point between a sol state and a gel state in the vicinity of 33 ° C., and a uniform gel state is obtained below this temperature. Therefore, this solution needs to be stored at a temperature equal to or higher than the pseudo phase transition temperature, preferably about the gel phase transition temperature plus about 10 ° C. However, this pseudo phase transition temperature differs depending on the total acetyl substitution degree, viscosity average polymerization degree, solution concentration, and organic solvent used in the cellulose ester.

A cellulose acylate film can be produced from the prepared cellulose ester solution (dope) by a solvent cast method.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. For casting and drying methods in the solvent casting method, U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,739,69, British Patent 6,407,331, No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 ° C. to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

(Co-casting)
In the present invention, the obtained cellulose ester solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose ester liquids of two or more layers may be cast. Also good. When casting a plurality of cellulose ester solutions, even if a film is produced while casting and laminating a solution containing a cellulose ester from a plurality of casting openings provided at intervals in the traveling direction of the metal support, For example, the methods described in, for example, JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Further, it may be formed into a film by casting a cellulose ester solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, This can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Also, a cellulose ester film casting method in which a flow of a high-viscosity cellulose ester solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose ester solution, and the high- and low-viscosity cellulose ester solution is simultaneously extruded. Good. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

  Alternatively, by using two casting ports, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side in contact with the metal support surface. Further, a film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose ester solution to be cast may be the same solution or different cellulose ester solutions and is not particularly limited. In order to give a function to a plurality of cellulose ester layers, a cellulose ester solution corresponding to the function may be extruded from each casting port. Further, the cellulose ester solution of the present invention may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, and a polarizing layer).

  In conventional single-layer liquids, it is necessary to extrude a high-concentration and high-viscosity cellulose ester solution to obtain the required film thickness. In this case, the stability of the cellulose ester solution is poor and solids are generated. In many cases, however, it becomes a problem due to a failure or poor flatness. As a solution to this, by casting multiple cellulose ester solutions from the casting port, a highly viscous solution can be extruded onto a metal support at the same time. In addition to being able to reduce the drying load by using a concentrated cellulose ester solution, the production speed of the film could be increased.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

  In the case of co-casting, a cellulose ester film having a laminated structure can be produced by co-casting cellulose ester solutions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose ester film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or an ultraviolet absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is contained only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing the cellulose ester at the time of casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

  A method of drying a web which has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position immediately before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or both ends of the peeled web are gripped by clips or the like. It is transported by a non-contact transport method. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferred. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of the solvents used. In the production of the film of the present invention, the web (film) peeled from the support is preferably stretched when the amount of residual solvent in the web is less than 120% by mass.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours. If the amount of residual solvent in the web is too large, the effect of stretching cannot be obtained, and if it is too small, stretching becomes extremely difficult and the web may break. A more preferable range of the residual solvent amount in the web is 10% by mass to 50% by mass, and most preferably 12% by mass to 35% by mass. Further, if the stretching ratio is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and breakage may occur.
In the present invention, the solution cast film can be stretched without being heated to a high temperature as long as the residual solvent amount is in a specific range, but it is preferable because drying and stretching can shorten the process. . However, since the plasticizer volatilizes when the temperature of the web is too high, a range of room temperature (15 ° C) to 145 ° C or less is preferable. Further, stretching in the biaxial directions perpendicular to each other is an effective method for bringing the refractive indexes Nx, Ny, and Nz of the film within the scope of the present invention. For example, when stretching in the casting direction, if the shrinkage in the width direction is too large, the value of Nz becomes too large. In this case, it can be improved by suppressing the width shrinkage of the film or stretching in the width direction. When stretching in the width direction, the refractive index may be distributed with a width. This is sometimes seen when using, for example, the tenter method, but it is a phenomenon that occurs when the film is stretched in the width direction and contraction force is generated at the center of the film and the end is fixed. It is thought to be called the Boeing phenomenon. Even in this case, by stretching in the casting direction, the bowing phenomenon can be suppressed, and the distribution of the width retardation can be improved. Furthermore, the film thickness fluctuation | variation of the film obtained by extending | stretching to the biaxial direction orthogonal to each other can be reduced. When the film thickness variation of the cellulose ester film is too large, the retardation becomes uneven. The film thickness variation of the cellulose ester film is preferably ± 3%, more preferably ± 1%. For the purposes as described above, a method of stretching in the biaxial directions orthogonal to each other is effective, and the stretching ratios in the biaxial directions orthogonal to each other are in the range of 1 to 2 times and 0.7 to 1.2 times, respectively. It is preferable to do. Here, stretching to 1.2 to 2.0 times with respect to one direction and making the other perpendicular to 0.7 to 1.0 times means that the distance between the clip or pin supporting the film is This means that the distance is 0.7 to 1.0 times the interval before stretching.

In general, when a biaxial stretching tenter is used to stretch in the width direction so as to have an interval of 1.2 to 2.0 times, a contracting force acts in the longitudinal direction, which is the perpendicular direction.
Therefore, if the force is applied in only one direction and the stretching is continued, the width in the perpendicular direction is reduced, but this means that the amount of shrinkage is suppressed with respect to the amount that shrinks without restricting the width. This means that the interval between the clip or pin whose width is restricted is restricted to a range of 0.7 to 1.0 times that before stretching. At this time, in the longitudinal direction, a force is exerted to shrink the film by stretching in the width direction. By taking the interval between the clips or pins in the longitudinal direction, an excessive tension is not applied in the longitudinal direction. There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by a linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

[Polarizer]
The polarizing plate of the present invention is a polarizing plate using the cellulose ester film of the present invention. In a typical polarizing plate, the cellulose ester film of the present invention is used as a protective film for a polarizer. That is, the polarizing plate is composed of a polarizer and two transparent protective films disposed on at least one side thereof, usually both sides. In the present invention, the cellulose ester film of the present invention is used as at least one protective film. As the other protective film, the cellulose ester film of the present invention may be used, or a normal cellulose acetate film or the like may be used.

As described above, the polarizing plate is formed by laminating and laminating a protective film for polarizing plate on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the cellulose ester film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. As this water-soluble polymer adhesive, a completely saponified polyvinyl alcohol aqueous solution is preferably used.
Moreover, you may have a phase difference film | membrane further on the protective film of a polarizing plate. The retardation film is preferably bonded with an adhesive. As an adhesive, the thing of Unexamined-Japanese-Patent No. 2000-109771, Unexamined-Japanese-Patent No. 2003-34781, and Unexamined-Japanese-Patent No. 2003-34781 is employable, for example.

  As a structure of the polarizing plate of the present invention, a protective film / polarizer / protective film / liquid crystal cell / cellulose ester film of the present invention / polarizer / polarizing plate protective film, or polarizing plate protective film / polarizer / present invention. The cellulose ester film / liquid crystal cell / cellulose ester film of the present invention / polarizer / polarizing plate protective film can be preferably used. In particular, by bonding to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is further excellent in viewing angle and visibility with little coloring. In particular, the polarizing plate using the cellulose ester film of the present invention is excellent in humidity stability under humidity change conditions and long-term wet heat durability under high-temperature and high-humidity conditions, and stable for a long time under high-temperature and high-humidity conditions. Performance can be maintained. Also, the haze value is low and excellent.

[Liquid Crystal Display]
The cellulose ester film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Charged Tunds). Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) a liquid crystal cell of a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Sharp Technical Report No. 80, page 11); (4) A SURVAVAL mode liquid crystal cell (Monthly Display May 14th page (1999)) is included.

  The VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmission type liquid crystal display device of the present invention, the film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Arrange two.

  In another aspect of the transmissive liquid crystal display device of the present invention, an optical compensation sheet made of the film of the present invention is used as a transparent protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The above optical compensation sheet may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. You may use said optical compensation sheet for a sheet of protective film. When the optical compensation sheet is used for only one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose ester film, and is preferably thinner than the film of the present invention. For example, it is preferably 40 to 80 μm, and examples thereof include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto), KC5UX (60 μm manufactured by Konica Caputo), TD80 (80 μm manufactured by Fuji Film), and the like.

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

[Example 1]
A film was produced by a solution casting method using the following cellulose ester dope a.
(Cellulose ester dope a)
Cellulose acetate resin: those having a substitution degree described in Table 4 below 100 parts by mass Additive A Amount described in Table 4 (unit: parts by mass)
Retardation developer AA 4 parts by weight Peeling accelerator 0.03 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight

なお、上記表３中、添加剤Ｊは２−ヒドロキシエチルメタクリレート、２−ヒドロキシエチルアクリレート、メタクリル酸を用いて合成した三元系共重合体である。また、２−ヒドロキシエチルメタクリレートと２−ヒドロキシエチルアクリレートの共重合比も特に制限はなく、便宜的に表１の同じ欄に共重合成分１として記載としてあるに過ぎない。 The composition of the additive A is shown in Table 3 below together with the compositions of the additives B to Z. When these additives are copolymers, the monomer components are referred to as copolymer component 1 and copolymer component 2, respectively, and their copolymerization ratios are shown in Tables 4 to 7 below. Moreover, the said polymerization ratio A and the said polymerization ratio B were described in following Tables 4-7.

In Table 3 above, additive J is a ternary copolymer synthesized using 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and methacrylic acid. Further, the copolymerization ratio of 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate is not particularly limited, and is merely described as copolymerization component 1 in the same column of Table 1 for convenience.

[Solution casting]
The cellulose ester dope a was put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a cellulose ester dope. The dope was cast with a band casting machine. The film having a residual solvent amount of about 30% by mass and peeled off from the band was dried by applying hot air of 140 ° C. with a tenter. Thereafter, the tenter transport was shifted to the roll transport, and further dried at 120 to 150 ° C. and wound up.
[Stretching]
After widening to a stretch ratio of 34% using a tenter, the film was relaxed at 140 ° C. for 60 seconds so that the stretch ratio was 30% to obtain a cellulose ester film. At this time, the film thickness was 60 μm.

[Examples 2-78, Comparative Examples 1-16]
The same as in Example 1 except that the substitution degree of the cellulose ester resin, the type and amount of the plasticizer, the type and amount of the additive, and the type and amount of the retardation enhancer were as shown in Tables 4 to 7 below. Thus, a cellulose ester dope was prepared. In Tables 4 to 7 below, plasticizer V is TPP, plasticizer W is BDP, plasticizers P-1, P-6, P-20, P-32, P-38, P-47, P- 52 to P-55, P-60 and P-64 represent the polymers exemplified in Table 1 and Table 2 as the polymer additive, and the addition amount of each plasticizer is expressed in units: parts by mass. It is. In Tables 4 to 7, the cellulose ester resin is a cellulose acetate resin in Examples 2 to 75 and Comparative Examples 1 to 16, and is a cellulose acetate propionate resin in Examples 76 to 78.
Thereafter, solution casting and stretching were performed in the same procedure as in Example 1, and cellulose ester films of Examples 2 to 78 and Comparative Examples 1 to 16 were obtained.

  Here, Comparative Example 1 and Example 1 compare the effects of additives when a cellulose acetate resin having a substitution degree of 2.81 is used. In Examples 1 to 5, the copolymerization ratio of the copolymerization component 1 and the copolymerization component 2 in the additive B is changed. In Examples 5 to 7, in the hydroxystyrene-acetoxystyrene copolymer, the position of the substituent of acetoxystyrene was changed to ortho, meta, and para. In Examples 8 to 10, the amount of the plasticizer was changed. In Examples 11 to 14, the amount of additive B added was changed. In Examples 15 to 18, the types of the retardation enhancer and the additive were changed from those in Examples 1, 2, 4 and 5, and the ratio of the B component was changed. In Examples 19 to 22, the amounts of the plasticizer and the additive were changed at the same time. In Examples 22 and 23 and Comparative Example 2, in the styrene-acetoxystyrene copolymer, the position of the substituent of acetoxystyrene was changed to ortho, meta, and para to compare the effects. In Examples 24-27, when the additive D was used, the amount of the plasticizer and the amount of the additive D were changed simultaneously. Example 28 is a film in which the amount of plasticizer was changed by fixing the additive D. In Comparative Examples 3 and 4, a vinyl pyrrolidone homopolymer and a styrene homopolymer were used as the polymer X having a B component of 0%. Examples 29 and 30 are compared with Comparative Examples 2 and 3 using a monomer X homopolymer that satisfies the conditions of the present invention. In Comparative Examples 5 to 7 and Examples 31 to 41, when a cellulose acetate resin having a substitution degree of 2.92 was used, the additives were changed and compared. In Comparative Examples 8 to 11 and Examples 42 to 52, when a cellulose acetate resin having a degree of substitution of 2.42 was used, the additives were changed and compared (particularly, Comparative Example 11 was published in International Publication 2007 / No. 119646 pamphlet described in comparison with Examples 42 to 52 using a terpolymer of 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate and methacrylic acid). Comparative Examples 12-14 and Examples 53-63 are different from Comparative Examples 8-10 and Examples 42-52, respectively, by changing the type and amount of plasticizer. Examples 64-75 change a plasticizer and a retardation expression agent. Comparative Example 15 compares the effect with the polymer X of the present invention using a styrene-maleic anhydride copolymer described in JP-A-2007-3043. Comparative Example 16 compares the effect with the polymer X of the present invention using a styrene-acrylic acid copolymer. Examples 64-66 change the total substitution degree using a cellulose acetate propionate resin.

[Test example]
(Evaluation of film properties)
Various physical properties of the cellulose ester films of Examples 1 to 78 and Comparative Examples 1 to 16 were evaluated according to the following methods.

[Evaluation of the physical properties]
Hereinafter, various properties of the film were measured and measured by the following methods.
(Retardation)
Rth was measured by KOBRA 21ADH (Oji Scientific Instruments) by the above method. The results are shown in Tables 4 to 7 below.

(Rth humidity stability)
The value of Rth at 25 ° C. and a relative humidity of 10% was measured and defined as Rth (10%). Further, the value of Rth at 25 ° C. and relative humidity of 80% was measured and set as Rth (80%). The value of ΔRth (10-80) was calculated from these values, and classified according to the following evaluation. The obtained evaluations are shown in Tables 4 to 7 below.
A: 12.5 nm or less, which is very preferable.
A: 12.5 to 15 nm, which is preferable.
A: 15 to 17.5 nm, which can be used without any practical problem.
(Triangle | delta): It is 17.5-20 nm, and there exists a problem practically.
X: It exceeds 20 nm and has a very practical problem.

(Rth wet heat durability)
Rth was measured after 24 hours at 60 ° C. and 90% relative humidity. The amount of change was calculated based on Rth at the time of film creation, and the absolute value was ΔRth (60 ° C. and 90% RH), and classification was performed according to the following evaluation. The obtained evaluations are shown in Tables 4 to 7 below.
A: 10 to 15 nm, which is practically preferable.
(Triangle | delta): It is 15-20 nm, and there is no problem practically.
X: It exceeds 20 nm and has a problem in practical use.

(Resistance to changes in wet heat)
The amount of film dimension change in the film transport direction (MD direction) before and after 24 hours at 60 ° C. and 90% relative humidity was calculated. The absolute values were classified according to the following evaluations. The obtained evaluations are shown in Tables 4 to 7 below.
A: 0.1 to 0.2%, practically preferable.
(Triangle | delta): It is 0.2 to 0.4%, and there is no problem practically.
X: Exceeding 0.4% or more, there is a problem in practical use.

From the above Tables 4 to 7, the cellulose ester films of Examples 1 to 78 to which the polymer X of the present invention was added were excellent in Rth humidity stability and Rth wet heat durability, and wet heat durability of dimensional change in the film transport direction. It was found to be excellent in performance. On the other hand, the cellulose ester films of Comparative Examples 1 to 16 to which the polymer X of the present invention was not added are all at least one of Rth humidity stability, ΔRth wet heat durability, and wet heat durability of dimensional change in the film transport direction. The physical properties of the seeds were in an unacceptable range for practical use.
In particular, Comparative Examples 2, 7, 10 and 14 use additive W which is a copolymer of p-acetoxystyrene and styrene, and Comparative Examples 6, 9 and 13 are copolymers of p-hydroxystyrene and styrene. In the case where the polymer X has only the monomer component having a substituent only at the para position of the phenyl group, the additive S is a substituent at the ortho position or the meta position of the phenyl group. It was found that the humidity stability of Rth was lower than that of the additives of other examples having a monomer component.
On the other hand, Examples 7, 35, 46 and 57 contain p-acetoxystyrene as a copolymer component, but contain m-hydroxystyrene, which is a monomer component having a substituent at the meta position of the phenyl group, as a copolymer component. Surprisingly, better results were obtained for humidity stability of Rth than when additive S or additive W was used.
Furthermore, the film of the example of the present invention was excellent in dimensional humidity stability as compared with the comparative example.

[Examples 101 to 178]
(Production of polarizer)
A polyvinyl alcohol (PVA) film having a thickness of 75 μm and a polymerization degree of 2400 was swollen with warm water at 30 ° C. for 40 seconds, and then immersed in an aqueous solution having an iodine concentration of 0.06% by mass and potassium iodide of 6% by mass at 30 ° C. for 60 seconds. Then, while immersed in an aqueous solution having a boric acid concentration of 4% by mass and potassium iodide of 3% by mass at 40 ° C. for 60 seconds, the longitudinal direction becomes 5.0 times the original length. Stretched. Then, it was made to dry at 50 degreeC for 4 minute (s), and the polarizer was obtained.

(Adjustment of cellulose ester film)
The film produced in Example 1 was placed in a 1.5 mol / liter sodium hydroxide aqueous solution at 30 ° C, and Fujifilm TD80U was placed in a 1.5 mol / liter sodium hydroxide aqueous solution at 55 ° C. After soaking, the sodium hydroxide was thoroughly washed away with water. Then, after dipping for 15 seconds in a 35 mol C dilute sulfuric acid aqueous solution at 0.05 mol / liter, the dilute sulfuric acid aqueous solution was sufficiently washed away by dipping in water. Finally, the sample was thoroughly dried at 120 ° C.

(Lamination)
The film saponified as described above and TD80U manufactured by Fuji Film Co., Ltd. were bonded using a polyvinyl alcohol adhesive so as to sandwich the polarizer, and further heated at 70 ° C. for 30 minutes. Thereafter, the sheet was cut with a cutter 3 cm from the width direction to produce a roll-shaped polarizing plate having an effective width of 1200 mm and a length of 50 m. At this time, since the polarizer and the protective films on both sides of the polarizer are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Moreover, in the protective film arrange | positioned at the cell side, the transmission axis of a polarizer and the slow axis of each cellulose acylate film are parallel.

(Preparation of adhesive layer)
n-butyl acrylate (n-BA) 75 parts by mass, methyl acrylate (MA) 20 parts by mass, 2-hydroxy acrylate (2-HEA) 5 parts by mass, ethyl acetate 100 parts by mass and azobisisobutyronitrile (AIBN) After 0.2 part by mass was put into a reaction vessel and the air in the reaction vessel was replaced with nitrogen gas, the reaction vessel was heated to 60 ° C. in a nitrogen atmosphere with stirring and reacted for 4 hours. After 4 hours, 100 parts by mass of toluene, 5 parts by mass of α-methylstyrene dimer and 2 parts by mass of AIBN were added, the temperature was raised to 90 ° C., and the mixture was further reacted for 4 hours. After the reaction, it was diluted with ethyl acetate to obtain an acrylic polymer solution having a solid content of 20% by mass. To 100 parts by mass of the solid content of the polymer solution, 1.0 part by mass of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred well to obtain an adhesive composition.

(Preparation of polarizing plate with adhesive)
A 25 μm pressure-sensitive adhesive layer is formed on a film obtained by removing the pressure-sensitive adhesive composition containing the acrylic polymer solution, and transferred to a polarizing plate (on the cell-side protective film). The temperature is 23 ° C. and the humidity is 65%. A polarizing plate with an adhesive was produced by aging under conditions for 7 days. Further, a separate film was pasted on the adhesive layer. A protective film was affixed on the protective film opposite to the cell. The obtained polarizing plate was used as the polarizing plate of Examples 101-178.

[Test Example 2]
(Durability of polarizing plate)
Two sets of polarizing plates of Examples 101 to 178 attached to a glass plate were prepared, and before and after aging at 60 ° C. and 90% RH for 1000 hours, parallel transmittance and orthogonal transmittance were measured with a Shimadzu UV3100 spectrophotometer. Was measured, and the degree of polarization was calculated. As a result, it was found that the polarizing plates of Examples 101 to 178 had a small change in the degree of polarization with respect to heat and humidity and were excellent in durability.

  Moreover, about the polarizing plate of the said Examples 101-178, the machine direction dimension change rate S (MD) and machine width direction dimension change rate S at the time of leaving still for 24 hours on the conditions of 60 degreeC and 90% of relative humidity. When (TD) was measured, the absolute values of the dimensional change rates S (MD) and S (TD) both showed good results of 1.0% or less.

[Examples 201 to 278]
(Mounting on VA panel)
VA mode liquid crystal TV (LC-20C5, manufactured by Sharp Corporation) is peeled off the front and back polarizing plates and retardation plates, and the polarizing plates and viewing angle compensation plates of Examples 101 to 178 are not provided on the front and back sides. A polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached using a laminator roll.
In this case, the absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the pressure-sensitive adhesive surface is on the liquid crystal cell side.

[Test Example 3]
(Viewing angle characteristics)
Using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle (range with a contrast ratio of 10 or more and no black-side gradation inversion) in 8 stages from black display (L1) to white display (L8) ) Was measured. The liquid crystal display devices using the polarizing plates of Examples 101 to 166 exhibited a good viewing angle of 80 degrees or more on both the left and right sides at 25 ° C. and a relative humidity of 60%. Thereafter, the liquid crystal display device is allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity, and then conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and again at 25 ° C. and 60% relative humidity. When the angle was measured, a good viewing angle of 80 degrees or more was shown on both the left and right sides.

  From this, it can be seen that the polarizing plate using the film according to the present invention has a small change in the degree of polarization with respect to heat and humidity, is excellent in durability, and exhibits excellent display performance.

In the present invention, there is provided a cellulose acylate film having a sufficiently small variation in retardation in the film thickness direction with respect to a change in humidity in the use environment and excellent in retardation in the film thickness direction and wet heat durability of dimensions. Became possible. That is, the cellulose acylate film of the present invention can be preferably used as a protective film for a polarizing plate and an optical compensation film.
Moreover, the polarizing plate of the present invention is excellent in wet heat durability. Therefore, the present invention can provide a liquid crystal display device in which variations in color shift, color, and light leakage are sufficiently small with respect to changes in humidity in the usage environment.

Claims (8)

Containing a cellulose ester resin, a polymer X having a weight average molecular weight of 500 to 100,000 and at least one retardation developer ,
Wherein the polymer X comprises at least one structural unit represented by the following general formula (4) or general formula (5), and meets the polymer X is represented by the following formula (1) and (2),
The cellulose ester resin is cellulose acetate;
The cellulose ester film, wherein the amount of the polymer X added is 2 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester resin .
30% ≦ A ≦ 100% (1)
(In the formula, A represents a polymerization ratio in the polymer X of a monomer in which the polymer exhibits negative birefringence when polymerized alone.)
10% ≦ B ≦ 100% (2)
(In the formula, B represents a polymerization ratio in the polymer X having the structure represented by the general formula (4) or the general formula (5) .)

(In General Formula (4) and General Formula (5), R ²¹ and R ²² each independently represent a hydrogen atom or a —C (═O) —CH ₃ group.)   Containing cellulose ester resin and polymer X having a weight average molecular weight of 500 to 100,000,
  The polymer X includes at least one structural unit represented by the following general formula (4) or general formula (5), and the polymer X satisfies the following formula (1) and formula (2):
  The cellulose ester resin is cellulose acetate propionate;
  The cellulose ester film, wherein the amount of the polymer X added is 2 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester resin.
30% ≦ A ≦ 100% (1)
(In the formula, A represents a polymerization ratio in the polymer X of a monomer in which the polymer exhibits negative birefringence when polymerized alone.)
10% ≦ B ≦ 100% (2)
(In the formula, B represents a polymerization ratio in the polymer X having the structure represented by the general formula (4) or the general formula (5).)

(In general formula (4) and general formula (5), R ^{twenty one} And R ^{twenty two} Each independently represents a hydrogen atom or —C (═O) —CH _Three Represents a group. ) Cellulose ester film according to claim 1 or 2, characterized by satisfying the following formula (3).
0 ≦ | ΔRth (10-80) | ≦ 20 nm (3)
(In the formula, ΔRth (10-80) represents the difference between the Rth value at 25 ° C. relative humidity of 10% and the Rth value at 25 ° C. relative humidity of 80%.) 60 ° C. The relative humidity of 90% 24 hours after the absolute value of the variation of Rth before and after ΔRth (60 ℃ 90% RH) is, according to any one of claims 1 to 3, characterized in that at 15nm or less Cellulose ester film. The cellulose ester according to any one of claims 1 to 4 , wherein an absolute value of a dimensional change amount of the cellulose ester film at about 60 ° C and a relative humidity of 90% is about 0.2% or less after 24 hours. the film. The total substitution degree of cellulose ester resin (DS) is a cellulose ester film according to any one of claims 1 to 5, characterized in that a 2.30 ≦ DS <2.98. A polarizing plate using the cellulose ester film according to any one of claims 1 to 6 . A liquid crystal display device using the cellulose ester film according to any one of claims 1 to 6 or the polarizing plate according to claim 7 .