JP2009298884A - Optical film, polarizing plate, and liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film exhibiting improved reversible and irreversible variation of a retardation value. <P>SOLUTION: The optical film contains cellulose acylate as the main component and at least one additive in an amount of 1-35 mass%. When the substitution degree of an acetyl group is represented by X; the substitution degree of a propionyl or butyryl group is represented by Y; and the acyl total substitution degree is represented by Z, the cellulose acylate is a cellulose ester which simultaneously satisfies the following formulas (1)-(3): formula (1) is 1.0≤X≤2.5; formula (2) is 0.3≤Y≤1.5; and formula (3) is 2.0≤Z≤3.0. A solubility parameter (SP value) of the cellulose acylate measured by a Hoy method and a solubility parameter (SP value) of the additive measured by a Hoy method satisfy ¾SP value (cellulose acylate)-SP value (additive)¾<2.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical film mainly composed of cellulose acylate, a polarizing plate, and a liquid crystal display device.

Conventionally, a retardation film having a specific retardation value and a combination thereof have been used to improve a viewing angle and a color change of a liquid crystal display device.
In addition, it is well known that cellulose acylate is effective as a main raw material for a retardation film. However, cellulose acylate changes reversibly and irreversibly with changes in the environment (especially in a humidity environment), and the retardation value may fluctuate, which causes fluctuations in the visibility of liquid crystal display devices. It was.
In order to improve this, various additives or production conditions have been proposed.

 Patent Document 1 discloses that when a compound having one furanose structure or one pyranose structure is contained in cellulose acylate, fluctuations in retardation values due to humidity fluctuations are suppressed. However, the defect that the retardation value changes irreversibly when exposed to high temperature and high humidity (60 ° C., 90% for 150 hours) has not been improved.

 Patent Document 2 discloses that the fluctuation of the retardation value due to humidity fluctuation is suppressed in a melt film-forming film containing styrene maleic anhydride in cellulose acylate. However, this technique cannot improve the disadvantage that the retardation value changes irreversibly when exposed to high temperature and high humidity (150 ° C., 90% for 150 hours).

International Publication WO2007 / 125765 Pamphlet International Publication WO2007 / 119646 Pamphlet

 An object of the present invention is to solve the above-mentioned problems, and is to improve reversible and irreversible changes in the retardation value due to the environment, which is a drawback of the conventional cellulose optical film. In particular, the object is to improve reversible and irreversible changes in the retardation value over time in humidity fluctuations and high humidity.

As a result of intensive studies by the inventor under the above problems, it has been found that the above problems can be solved by the following means.
(1) An optical film comprising cellulose acylate as a main component and containing 1 to 35 mass% of at least one additive, wherein the cellulose acylate has a substitution degree of acetyl group as X, and is a propionyl group or butyryl When the substitution degree of the group is Y and the total acyl substitution degree is Z, it is a cellulose ester that simultaneously satisfies the following formulas (1) to (3), and the solubility parameter (SP value) of the cellulose acylate measured by the Hoy method ) And the solubility parameter (SP value) of the additive measured by the Hoy method satisfying | SP value (cellulose acylate) −SP value (additive) | <2.0.
Formula (1) 1.0 <= X <= 2.5
Formula (2) 0.3 <= Y <= 1.5
Formula (3) 2.0 ≦ Z ≦ 3.0
(2) The difference between the maximum value and the minimum value of the solubility parameter (SP value) of each additive, measured by the Hoy method, is at least 2% by mass, and the difference between the maximum value and the minimum value is | SP value (maximum value) ) -SP value (minimum value) | <1.5 which satisfies | fills the optical film as described in (1).
(3) The optical film according to (1) or (2), wherein the additive has a molecular weight of 700 or more and less than 10,000.
(4) The optical film according to any one of (1) to (3), wherein a total of 4 to 30% by mass of additives are added to the cellulosic resin.
(5) The optical film according to any one of (1) to (4), wherein 25 nm ≦ | Re (590) | ≦ 100 nm and 50 nm ≦ | Rth (590) | ≦ 250 nm are satisfied.
(6) The optical film according to any one of (1) to (5), wherein the film thickness is 30 to 100 μm.
(7) The optical film according to any one of (1) to (6), which is obtained by stretching after film formation by a solution casting film formation method.
(8) A polarizing plate having the optical film according to any one of (1) to (7).
(9) A liquid crystal display device having the polarizing plate according to (8).
(10) The liquid crystal display device according to (9), wherein the liquid crystal display device is a VA type.

 It has become possible to provide a film in which the irreversible change in the retardation value with aging at high temperature and high humidity is remarkably improved. Furthermore, it is possible to remarkably improve the change in film dimensions when the temperature is high and high.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

The optical film of the present invention is an optical film containing cellulose acylate as a main component and containing 1 to 35% by mass of at least one additive, wherein the cellulose acylate has an acetyl group substitution degree of X, When the substitution degree of propionyl group or butyryl group is Y and the total acyl substitution degree is Z, it is a cellulose ester that simultaneously satisfies the following formulas (1) to (3), and the solubility of the cellulose acylate measured by the Hoy method The parameter (SP value) and the solubility parameter (SP value) of the additive measured by the Hoy method satisfy | SP value (cellulose acylate) −SP value (additive) | <2.0. .
Formula (1) 1.0 <= X <= 2.5
Formula (2) 0.3 <= Y <= 1.5
Formula (3) 2.0 ≦ Z ≦ 3.0
It is characterized by.

(1) ΔSP Value In the present invention, | SP value (cellulose acylate) −SP value (additive) | (hereinafter sometimes referred to as “ΔSP value”) is less than 2.0. When ΔSP is 2.0 or more, the compatibility is deteriorated and whitening and crying occur. Moreover, when the dope used for film formation of such a film is formed by a solution casting method, whitening occurs due to moisture in the dope. The value of ΔSP is preferably less than 1.5, more preferably less than 1.2. When two or more additives are used, the ΔSP value of each additive needs to satisfy the above range. Moreover, when adding 2 or more types of additives, it is preferable that (DELTA) SP value of additives also satisfy | fill the said range. That is, the difference between the maximum value and the minimum value of the solubility parameter (SP value) of each additive measured by the Hoy method satisfies | SP value (maximum value) −SP value (minimum value) | <1.5. Is preferred.
The SP value in the present invention is a value calculated by the Hoy method, and the Hoy method is described in POLYMER HANDBOOK FOURTH EDITION.

(2) Cellulose ester The cellulose ester used in the present invention has an acyl group with an acetyl group substitution degree of X, a propionyl group or butyryl group substitution degree of Y, and an acyl total substitution degree of Z. It is a cellulose ester containing the cellulose ester which satisfy | fills Formula (1)-(3) simultaneously.

Formula (1) 1.0 <= X <= 2.5
Formula (2) 0.3 <= Y <= 1.5
Formula (3) 2.0 ≦ Z ≦ 3.0
More preferably, 1.5 ≦ X ≦ 2.3, 0.5 ≦ Y ≦ 1.3, and 2.0 ≦ Z ≦ 2.8.
The portion that is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized and measured for the degree of substitution by the method described in JP-A-10-45804.
The cellulose ester satisfying the above (1) to (3) is excellent in polarization degree durability and light leakage prevention while expressing a phase difference. Further, from the viewpoint of heat resistance, the propionyl group is more advantageous than the butyryl group.
The cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) value of 1.4 to 3.0, more preferably 1.4 to 2.2. It is.
This range of Mw / Mn is preferable from the viewpoint of retardation development and white turbidity prevention when the cellulose ester film is stretched. This is presumably because the smaller the Mw / Mn value, the smaller the molecular weight distribution, so that the polymer molecules are more easily oriented and a uniform film with fewer voids. However, if the value of Mw / Mn is too small, an increase in production cost or a decrease in molecular weight is likely to occur, so it is practical to set the value to 1.4 or more.
The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high performance liquid chromatography. Using these, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (Mw / Mn) can be calculated. The molecular weight of the cellulose ester is preferably 60000-200000 in terms of number average molecular weight (Mn), more preferably 70000-170000. If the molecular weight of the cellulose ester is large, the rate of change of the retardation value due to humidity becomes small. However, if the molecular weight is too high, the viscosity of the cellulose ester solution becomes too high and the productivity may decrease.
As the cellulose ester, cellulose ester synthesized using cotton linter, wood pulp, kenaf or the like as a raw material can be used alone or in combination. In particular, it is preferable to use a cellulose ester synthesized from cotton linter (hereinafter sometimes simply referred to as linter) alone or in combination.
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 groups of cellulose located at the 2nd, 3rd and 6th positions are esterified (100% esterification has a degree of substitution of 1).

  The acyl group having 2 or more carbon atoms of the cellulose ester in 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. Propionyl group and butanoyl group.

  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.

  In the film of the present invention, additives such as plasticizers such as phthalic acid esters and phosphoric acid esters, ultraviolet absorbers, antioxidants and matting agents may be added.

(3) Additives In the present invention, high molecular weight additives and low molecular weight additives known as additives for cellulose acylate films can be widely used as additives. The content of the additive is 1 to 35% by mass, preferably 4 to 30% by mass, and more preferably 10 to 25% by mass with respect to the cellulose resin. If the addition amount is 1% by mass or less, it is not possible to cope with changes in temperature and humidity, and if the addition amount is 30% by mass or more, the film is whitened. In addition, the physical characteristics will be inferior.
Here, the additive in the present invention is a component added for the purpose of improving various functions of the optical film of the present invention, and a component contained in a range of 1% by mass or more with respect to the cellulose resin. Say. That is, impurities, residual solvents, and the like are not additives in the present invention. In the present invention, the content of the high molecular weight additive is preferably 4 to 30% by mass with respect to the cellulosic resin. More preferably, it is mass%.
In the present invention, two or more kinds of additives can be used as long as the value of ΔSP is within a predetermined range. By using two or more types, each additive has the merit that both optical properties, film elastic modulus, film brittleness, and web handling suitability can be achieved.

(High molecular weight additive)
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 700 or more and 10,000 or less. 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 exhibits useful effects 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.

  The polymer additive is selected from polyester polymers, styrene polymers, acrylic polymers, and copolymers thereof, and aliphatic polyesters, aromatic polyesters, acrylic polymers, and styrene polymers are 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 preservability that the end capping is performed in order 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 can 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.
Specific examples of the polyester-based polymer that can be used in the present invention are described below, but the polyester-based polymer that can be used in the present invention is not limited thereto.

表１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 Table 1, 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, and 1,8-NPA is 1,8-naphthalenedicarboxylic acid is shown respectively.

式中、Ｒ¹〜Ｒ⁴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、Ｒ⁴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。これらのうち、工業的に入手が容易で、かつ安価な点で、スチレン、α−メチルスチレンが好ましい。 Styrenic polymer The styrenic polymer is preferably a structural unit obtained from an aromatic vinyl monomer represented by the general formula (I).
Formula (I)

In the formula, each of R ^{1 to} R ⁴ 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 ⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ^{4 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. Of these, styrene and α-methylstyrene are preferred because they are easily available industrially and are inexpensive.

式中、Ｒ⁵〜Ｒ⁸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。 Acrylic Polymer The acrylic polymer is preferably a structural unit obtained from an acrylate ester monomer represented by the general formula (II).
Formula (II)

In the formula, R ^{5 to} R ⁸ 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. It represents a hydrocarbon group of 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、Ｒ¹〜Ｒ⁴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、Ｒ⁴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。
一般式（ＩＩ）

式中Ｒ⁵〜Ｒ⁸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-アクリル酸共重合体、スチレン-無水マレイン酸共重合体、スチレン-アクリロニトリル共重合体が特に好ましい。 Copolymer The copolymer comprises at least one structural unit obtained from an aromatic vinyl monomer represented by the general formula (I) and an acrylate monomer represented by the general formula (II). The inclusion is preferred.
Formula (I)

In the formula, each of R ^{1 to} R ⁴ 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 ⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ^{4 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.
Formula (II)

In the formula, each of R ^{5 to} R ⁸ independently has a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom, and the number of substituted or unsubstituted carbon atoms 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, etc. acid anhydrides, 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, styrene-acrylic acid copolymers, styrene-maleic anhydride copolymers, and styrene-acrylonitrile copolymers are particularly preferred.

(Low molecular weight additive)
Examples of the low molecular weight additive include a retardation reducing agent / conditioning agent, a deterioration preventing agent, an ultraviolet ray preventing agent, a peeling accelerator, another plasticizer, and an infrared absorber. 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 may be added by adding an additive 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.

（式中、Ｒ¹はアルキル基またはアリール基を表し、Ｒ²およびＲ³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。Ｒ¹、Ｒ²およびＲ³の炭素原子数の総和は１０以上である。）
一般式（５）

（式中、Ｒ⁴およびＲ⁵は、それぞれ独立に、アルキル基またはアリール基を表す。Ｒ⁴およびＲ⁵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 (4)-(10) described below is mentioned.
General formula (4)

(In the formula, R ¹ represents an alkyl group or an aryl group, R ² and R ³ are each independently a hydrogen atom, an alkyl group or an aryl group .R ^1, R ² and R ³ the number of carbon atoms The sum is 10 or more.)
General formula (5)

(In the formula, R ⁴ and R ⁵ 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.)

In the general formula (4), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ 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 ¹ , R ² and R ³ is 10 or more. In the general formula (5), R ⁴ and R ⁵ 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 (4) or General formula (5) is shown below, this invention is not limited to these specific examples.

The compound represented by the general formula (4) or the general formula (5) can be prepared by the following method.
The compound of the general formula (4) can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative. The compound of the general formula (5) 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 (6) will be described in detail.
General formula (6)

In the general formula (6), R ¹¹ represents an aryl group. R ¹² and R ¹³ each independently represents an alkyl group or an aryl group, and at least one of them is an aryl group. When R ¹² is an aryl group, R ¹³ 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 (7) will be described in detail.
General formula (7)

In the general formula (7), R ²¹ , R ²² and R ²³ each independently represents an alkyl group. Here, the alkyl group may be linear, branched or cyclic. R ²¹ is preferably a cyclic alkyl group, and more preferably at least one of R ²² and R ²³ is 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 (6) and (7) 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 (6) and (7) is shown below, this invention is not limited to these specific examples.

Next, the compound represented by the general formula (8) will be described.
General formula (8)

In the general formula (8), 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, still more 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 (8) is preferably a compound represented by the following general formula (8-1).
General formula (8-1)
R ³¹¹ -X ³¹¹ -Z ³¹¹ -X ³¹² -R ³¹²

In the general formula (8-1), 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 (8-1) is preferably a compound represented by the following general formulas (8-2) to (8-4).
Formula (8-2)

General formula (8-3)

General formula (8-4)

In the above general formulas (8-2) to (8-4), 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 thereof include isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. 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 carbon atoms, particularly preferably 6 to 1 carbon atoms). 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, Benzoylamino group), alkoxycarbonylamino group (preferably having 2 to 2 carbon atoms) 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, a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group, a piperidyl group, a morpholino group, a benzoxazolyl group, a benzimidazolyl group 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 (8) are shown below, but the present invention is not limited to these specific examples.

  The compounds of general formula (6), general formula (7), and general formula (8) 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, and more preferably 0.1 to 10% with respect to 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 two or more types of retardation reducing agents are used, the total amount is preferably within the above range.

(Retardation adjuster)
In the present invention, since a retardation value is expressed, it is preferable to use a retardation adjusting agent. Examples of the retardation adjusting agent that can be used in the present invention include those composed of rod-like 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 adjusting agent. The addition amount of the retardation adjusting agent composed of the rod-shaped compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred.
The disk-shaped retardation adjusting agent is preferably used in a range of 0.05 to 20 parts by mass, and in a range of 1.0 to 15 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. It is more preferable to use, and it is still more preferable to use in the range of 3.0-10 mass parts.
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 types of retardation adjusting agents may be used in combination.
The retardation adjusting agent preferably has 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 adjusting agent is preferably 2-20, more preferably 2-12, further preferably 2-8, and 2-6. Most preferred.
The bond relationship between two aromatic rings can be classified into (a) a condensed ring, (b) a direct bond with a single bond, and (c) a bond through 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-methoxyethyl. 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 adjusting agent is preferably 300 to 800.

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

Formula (I)

In the above general formula (I):
R ¹² 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 ¹³ —. Here, each R ¹³ 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 ¹² is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ¹² 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 ¹² 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. Here, -C ₄ H ₉ ⁿ represents a n-C ₄ H _9.

The alkyl group represented by R ¹³ 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 ¹³ 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 ¹³ 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 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 ¹² .

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

Formula (II)

In the general formula (II), R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or a substituent.
As the substituents represented by R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ , 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 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms). Alkynyl groups such as propargyl group and 3-pentynyl group), aryl groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). An aryl group, 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 a methoxycarbonyl group and an ethoxycarbonyl group), an aryloxycarbonyl group (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, such as 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 substituent represented by each of R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group or a halogen atom. is there.

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

  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 (1) is preferable.

Formula (1): Ar ¹ -L ¹ -Ar ²

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

As the rod-like compound, a compound represented by the following formula (2) is more preferable.
Formula ^{(2): Ar 1 -L 2} -X-L 3 -Ar 2

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

In the general formula (2), L ² and L ³ 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 ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In General formula (2), X is a 1, 4- cyclohexylene group, vinylene group, or an ethynylene group.

  Specific examples of the compound represented by the general formula (1) or (2) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

Other preferred compounds are shown below.

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).

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3) is added to the cellulose acylate solution. -Methylphenol), 1,1'-bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythris Phenolic or hydroquinone antioxidants such as lithyl-tetrakis [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 phosphorus-based antioxidants such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The addition amount of the deterioration inhibitor 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 acylate 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 a small 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 -Chlorbenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm by mass in the whole optical film.

(Peeling accelerator)
The film of the present invention may contain a peeling accelerator. The peeling accelerator can be included at a ratio of 0.001 to 1% by weight, 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) 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. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass based on the mass of the cellulosic resin.

(4) Characteristics of optical film (haze)
The optical film of the present invention preferably has a haze of less than 1%, and more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as an optical film.

(Average moisture content)
In the optical film of the present invention, the equilibrium moisture content at 25 ° C. and a relative humidity of 60% is preferably 4% or less, and more preferably 3% or less. By setting the average moisture content to 4% or less, it is easy to cope with a change in humidity, and it is preferable that optical characteristics and dimensions are less likely to change.

(Re, Rth)
The preferred range of the retardation value of the optical film of the present invention varies depending on its use. For example, when used for a polarizing plate of a VA mode liquid crystal display device, it is preferable that 25 ≦ Re (590) ≦ 100, more preferably 40 ≦ Re (590) ≦ 80, and 45 ≦ Re. More preferably, (590) ≦ 65. Further, 80 ≦ Rth (590) ≦ 250 is preferable, 90 ≦ Rth (590) ≦ 200 is more preferable, and 95 ≦ Rth (590) ≦ 130 is further preferable.

  In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. 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 formulas (1) and (2) 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 acylate (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 −−− Formula (2)
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.

(ΔRth)
The optical film of the present invention has a difference (ΔRth) of 20 nm or less between Rth (Rth (10%)) at 25 ° C. and 10% relative humidity and Rht (Rth (80%)) at 25 ° C. and 80% relative humidity. It is preferably some 15 nm or less. Thus, when the humidity change is small, the optical characteristics are more excellent.
(ΔRe)
The optical film of the present invention has a difference (ΔRe) of 20 nm or less between Re (Re (10%)) at 25 ° C. and a relative humidity of 10% and Re (Re (80%)) at 25 ° C. and a relative humidity of 80%. It is preferably some 15 nm or less. Thus, when the humidity change is small, the optical characteristics are more excellent.

(Film thickness)
The film thickness of the optical film of the present invention is preferably 30 to 100 μm, more preferably 30 to 80 μm, and further preferably 30 to 70 μm. By setting it to 30 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 70 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.

(Dimensional change rate)
The cellulose acylate film of the present invention has a machine direction dimensional change rate S (MD) and a machine width direction dimensional change rate S (TD) when allowed to stand for 24 hours at 60 ° C. and 90% relative humidity. All indicate that they are in the range of ± 1.0%. In order to obtain a film having such a dimensional change rate, it is preferable to adjust the amount, (type), and the like of the additive with respect to the total DS of the cellulose acylate. Moreover, in order to satisfy | fill said performance, adding together and using 2 or more types of additives is also used preferably.

  Here, the machine direction dimensional change rate S (MD) and the machine width direction dimensional change rate S (TD) are respectively the machine transport direction (casting direction during casting) and the machine width direction (flow rate) when creating a protective film. It means the dimensional change rate in the width direction). Specifically, it is obtained by the following method.

A method for obtaining the machine direction dimensional change rate S (MD) will be described.
A 50 mm x 250 mm sample cut out from the film is conditioned for 2 days or more in an atmosphere of 25 ° C and 60% relative humidity, and then in the machine direction at the time of film creation with an automatic pin gauge (manufactured by Shinto Kagaku Co., Ltd.). Holes of 6 mmφ are opened at intervals of 200 mm so as to be parallel, and the original size (L1) of the interval is measured to a minimum scale of 1/1000 mm. Then, after thermo-treating at 60 ° C. and 90% relative humidity for 150 hours, or at 80 ° C. and 10% relative humidity for 120 hours, the temperature was adjusted to 25 ° C. and 60% relative humidity for 24 hours, and the punch spacing dimension (L2 ). The machine direction dimensional change rate can be obtained by the following equation.
Machine direction dimensional change rate S (MD) = {(L2-L1) / L1} × 100

  Further, the dimensional change rate S (TD) in the machine width direction can be obtained by the same method as described above except that a hole by an automatic pin gauge is formed in the machine width direction at the time of film production.

  The machine direction dimensional change rate S (MD) and the machine width direction dimensional change rate S (TD) when the cellulose acylate film of the present invention is allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity. Both are preferably within ± 1.0%, more preferably within ± 0.5%, and even more preferably within ± 0.3%.

(5) Production of Film The film of the present invention can be widely used by a known method for producing a 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 acylate 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 acylate 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 amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, cellulose acylate and an 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, cellulose acylate 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 acylate 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, cellulose acylate is gradually added to an organic solvent at room temperature while stirring. The amount of cellulose acylate is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of cellulose acylate 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 way, the mixture of cellulose acylate 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.
Furthermore, 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.), cellulose acylate dissolves 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 acylate (total acetyl substitution degree: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by the cooling dissolution method is In the vicinity of 33 ° C., there exists a quasi-phase transition point between the sol state and the gel state, 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 varies depending on the total acetyl substitution degree, viscosity average polymerization degree, solution concentration, and organic solvent used in the cellulose acylate.

From the prepared cellulose acylate solution (dope), a cellulose acylate film can be produced 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. The casting and drying methods in the solvent casting method are described in U.S. Pat. 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.

  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 preferable. 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. The more preferable range of the residual solvent amount in the web is most preferably 10% by mass to 50% by mass, particularly 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 bowing phenomenon. Even in this case, by stretching in the casting direction, it is possible to suppress the bowing phenomenon and to improve the distribution of the width retardation. Furthermore, the film thickness fluctuation | variation of the film obtained by extending | stretching to the biaxial direction orthogonal to each other can be reduced. If the film thickness variation of the optical film is too large, the retardation will be uneven. The film thickness variation of the optical film is preferably in the range of ± 3%, and 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 1.2 to 2.0 times and 0.7 to 1.0, respectively. It is preferable that the range be doubled. 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 the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

 Further, in the present invention, the obtained cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. You may cast. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Further, a film may be formed by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-6-247245 It can be carried out by the methods described in JP-A-61-104813, JP-A-61-158413, and JP-A-6-134933. Further, a cellulose acylate in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high-viscosity and low-viscosity cellulose acylate solutions are simultaneously extruded. A film casting method may be used. Furthermore, it is also a preferable 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, peeling the film formed on the metal support by the first casting port, and performing the second casting on the side that was in contact with the metal support surface, A film may be produced, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Further, the cellulose acylate 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, a polarizing layer). .

 In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a required film thickness. In many cases, a problem occurred due to the occurrence of an object, a fault, or poor flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also a concentrated cellulose acylate solution can be used to reduce the drying load and increase the film production speed.

 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 acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as a plasticizer, an ultraviolet absorber, and a matting agent. For example, a cellulose acylate 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 kind 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 cellulose acylate during 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.

(6) Polarizing plate Since the optical film of the present invention has water barrier properties and a low moisture content, it is preferably used for a protective film for polarizing plates. The polarizing plate is formed by laminating and laminating a protective film 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. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.

  The film of the present invention is a protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / film of the present invention / polarizer / protective film for polarizing plate, or protective film for polarizing plate / polarizer / It can use preferably by the structure of the film / liquid crystal cell of this invention / film of this invention / polarizer / protective film for polarizing plates. 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, a polarizing plate using the protective film for a polarizing plate of the present invention has little deterioration under high temperature and high humidity conditions, and can maintain stable performance for a long time.

(7) Liquid Crystal Display Device The cellulose acylate film of the present invention and a 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 Crystals), AFLC (Anti-Ferroelectric Liquid Crystals), OCB (Optically Charged TNS). Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

  The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. The bend alignment mode liquid crystal display device has an advantage of high response speed.

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 A
(Preparation of cellulose acylate)
Cellulose acylate was synthesized by the method described in JP-A-10-45804 and JP-A-8-231761, and the degree of substitution was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, a carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

[Evaluation of the physical properties]
Hereinafter, various properties of the film were measured and measured by the following methods.
(Retardation)
As described above, measurement was performed with KOBRA 21ADH (manufactured by Oji Scientific Instruments).

(Dimensional change)
The machine direction dimensional change rate S (MD) and the machine width direction dimensional change rate S (TD) when the cellulose acylate film was allowed to stand for 24 hours under the conditions of 60 ° C. and relative humidity 90% were measured. . The definition and measurement method of the dimensional change rate S (MD) in the casting direction and the dimensional change rate S (TD) in the casting width direction are as described above.

(Compatibility)
Evaluation was shown as follows.
○: Completely transparent after film formation Δ: Partial turbidity was observed after film formation ×: White turbidity was observed on the entire film surface after film formation

(Calculation of solubility parameter (SP value))
All the solubility parameters (SP values) in the present invention were values calculated by the Hoy method.

A film was prepared by solution casting using the cellulose acylate dope shown below.
(Cellulose acylate dope A)
Cellulose acylate resin: Substituents described in Table 3, those having a substitution degree 100 parts by mass Additive A: Those described in Table 2 Amounts described in Table 3 (unit: parts by mass)
Additive B: those listed in Table 2 Amounts listed in Table 3 (unit: parts by mass)
Additive C: 4 parts by mass of the following compound A Peeling accelerator: Mixture of the following compound B and the following compound C 0.03 parts by mass Dichloromethane 406 parts by mass Methanol 61 parts by mass

(Solution casting method)
The cellulose acylate dope 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 acylate 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 conveyance was shifted to the roll conveyance, and the film was further dried at 120 to 150 ° C. and wound up. The film thickness at this time is shown in Table 3.

(Stretching)
After widening to a stretch ratio of 30% using a tenter, the film was relaxed at 140 ° C. for 60 seconds to obtain a film.

上記表中、比較例１および比較例４は、相溶性が悪く、膜状に形成されなかった。また、比較例５および比較例６は、膜が白濁し、Ｒｅ、Ｒｔｈおよび寸法を測定できなかった。

In the above table, Comparative Example 1 and Comparative Example 4 had poor compatibility and were not formed into a film. In Comparative Example 5 and Comparative Example 6, the film was clouded, and Re, Rth, and dimensions could not be measured.

From the above results, the film of the present invention, _delta Re and _delta Rth is small, it can be seen that excellent optical properties. Furthermore, the film of the present invention is excellent in compatibility. Comparative Examples 2 and 3, _delta Re and _delta Rth is large, inferior in optical characteristics.

Example B Production of Polarizing Plate (Production of Polarizing Plate)
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.

The film produced in Example A 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 dilute sulfuric acid aqueous solution at 0.05 mol / liter at 35 ° C., the dilute sulfuric acid aqueous solution was sufficiently washed away by dipping in water. Finally, the sample was thoroughly dried at 120 ° C.
The film subjected to the saponification treatment 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. The produced polarizing plates are shown in the following table.

Example C Mounting on a panel (Mounting on a VA panel)
The polarizing plate and the retardation plate on the front and back sides of the VA mode liquid crystal TV (LC-20C5, manufactured by Sharp Corporation) are peeled off, and the modified plate of Example B is placed on the front and back sides at a temperature of 23 ° C. and a humidity of 65%. A polarizing plate which was aged for 7 days under conditions and a commercially available polarizing plate without a viewing angle compensator (HLC2-5618, manufactured by Sanlitz Co., Ltd.) were attached in a combination of the following table 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.

(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 device using the polarizing plate of the present invention and the comparative example showed 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, the right viewing angle of 80 degrees or more on both the left and right sides was rated as “◯”, and the other cases were marked as “x”.

  From the above table results, it is understood that the polarizing plate using the film according to the present invention is a polarizing plate having a small change in the degree of polarization with respect to heat and humidity, excellent durability, and excellent display performance.

According to the present invention, it has become possible to provide a cellulose acylate film having sufficiently small dimensional variations with respect to changes in humidity in the usage environment and having excellent wet heat durability with optical characteristics. 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 (10)

An optical film comprising cellulose acylate as a main component and containing 1 to 35% by mass of at least one additive, wherein the cellulose acylate has a substitution degree of acetyl group as X and is substituted with propionyl group or butyryl group. The cellulose ester satisfying the following formulas (1) to (3) when the degree is Y and the total acyl substitution degree is Z, the solubility parameter (SP value) of the cellulose acylate measured by the Hoy method and Hoy An optical film in which the solubility parameter (SP value) of the additive measured by the method satisfies | SP value (cellulose acylate) −SP value (additive) | <2.0.
Formula (1) 1.0 <= X <= 2.5
Formula (2) 0.3 <= Y <= 1.5
Formula (3) 2.0 ≦ Z ≦ 3.0 The difference between the maximum value and the minimum value of the solubility parameter (SP value) of each additive measured by the Hoy method is at least 2% by mass, and the difference between the maximum value and the minimum value is | SP value (maximum value) -SP The optical film according to claim 1, satisfying a value (minimum value) | <1.5. The optical film according to claim 1 or 2, wherein the additive has a molecular weight of 700 or more and less than 10,000. The optical film according to any one of claims 1 to 3, wherein the additive is added in a total amount of 4 to 30% by mass with respect to the cellulose resin. 5. The optical film according to claim 1, wherein 25 nm ≦ | Re (590) | ≦ 100 nm and 50 nm ≦ | Rth (590) | ≦ 250 nm are satisfied. The optical film of any one of Claims 1-5 whose film thickness is 30-100 micrometers. The optical film according to claim 1, which is obtained by stretching after film formation by a solution casting film formation method. The polarizing plate which has an optical film of any one of Claims 1-7. A liquid crystal display device comprising the polarizing plate according to claim 8. The liquid crystal display device according to claim 9, wherein the liquid crystal display device is a VA type.