JP2016206540A - Retardation film, polarizing plate, vertically-oriented liquid crystal display device, and manufacturing method for retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retardation film which allows for increasing an amount of nitrogen-containing heterocyclic compound to be added and suppresses variation of retardation caused by moisture absorption.SOLUTION: A retardation film used as an optical film 13 of a polarizing plate 5 or an optical film 15 of a polarizing plate 6 contains cellulose ester and a nitrogen-containing heterocyclic compound, and exhibits a humidity expansion coefficient of 0.1-1.0% when ambient humidity changes from 5%RH to 90%RH. The cellulose ester satisfies 2.0≤X+Y≤2.9 and 0.1≤Y≤0.8 regarding the substitution degree, where X represents a substitution degree of acetyl group and Y represents a substitution degree of butyryl group.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a retardation film, a polarizing plate having a retardation film, a vertical alignment liquid crystal display device, and a method for producing a retardation film.

  In a vertical alignment type liquid crystal display device using a cellulose-based retardation film, there has been a problem that unevenness in which the color and luminance of the display panel change due to the variation in retardation due to moisture absorption of the retardation film has been a problem. A retardation film using cellulose acetate butyrate has also been proposed as in the prior art described in Patent Documents 1 and 2, but the improvement in retardation variation due to moisture absorption is insufficient and unevenness has occurred.

  Further, the conventional retardation film has insufficient retardation, and it has been difficult to reduce the thickness of the liquid crystal display device in recent years while maintaining a desired retardation. In order to reduce the thickness of the retardation film while maintaining the retardation satisfying the display performance, it is known to use a retardation increasing agent. Such retardation increasing agents for retardation films are described in Patent Document 3, for example.

International Publication No. 2014/104616 International Publication No. 2014/142465 JP 2012-82235 A

  However, the conventional retardation film has a problem that the nitrogen-containing heterocyclic compound contained in the retardation increasing agent is difficult to dissolve in the methylene chloride solvent used in the production of the retardation film. Thereby, the addition amount of the nitrogen-containing heterocyclic compound, that is, the retardation increasing agent could not be increased.

  The present invention has been made in view of the above points, a retardation film capable of increasing the amount of addition of a nitrogen-containing heterocyclic compound, and capable of suppressing retardation fluctuation due to moisture absorption, and the retardation film thereof. It is an object of the present invention to provide a polarizing plate, a vertical alignment type liquid crystal display device, and a method for producing the retardation film.

1. A retardation film formed by a solution casting method, comprising a cellulose ester that satisfies both the following formulas (1) and (2) relating to the degree of substitution, and a nitrogen-containing heterocyclic compound, and has an environmental humidity of 5% RH A retardation film having a humidity expansion coefficient of 0.1 to 1.0% when changed from 90 to RH.
Formula (1) 2.0 <= X + Y <= 2.9
Formula (2) 0.1 <= Y <= 0.8
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the butyryl group.)

  2. 2. The retardation film as described in 1 above, comprising at least one of a sugar ester and a polycondensed ester.

  3. A polarizing plate comprising the retardation film as described in 1 or 2 above.

  4). 4. A vertical alignment type liquid crystal display device comprising the polarizing plate according to 3 above.

  5. A method for producing a retardation film, wherein the retardation film according to 1 or 2 is formed by a solution casting method, wherein a web formed by casting a resin composition containing a cellulose ester on a metal support is formed. A method for producing a retardation film, comprising a step of stretching and drying, wherein the step is performed at a drying temperature of (glass transition temperature Tg-30) ° C. or lower.

  According to the configuration of the present invention, the amount of addition of the nitrogen-containing heterocyclic compound can be increased and retardation retardation due to moisture absorption can be suppressed, a polarizing plate having the retardation film, and a vertical alignment type A liquid crystal display device and a method for producing the retardation film can be provided.

It is sectional drawing which shows schematic structure of the vertical alignment type liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the manufacturing apparatus of the retardation film which concerns on embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. In the present specification, when the numerical range is expressed as A to B, the numerical value range includes the values of the lower limit A and the upper limit B. The present invention is not limited to the following contents.

[Outline of retardation film]
In the present embodiment, the amount of the nitrogen-containing heterocyclic compound added to the retardation film can be increased, and the following configuration is used to suppress retardation fluctuation due to moisture absorption. That is, the retardation film of this embodiment contains a cellulose ester and a nitrogen-containing heterocyclic compound, and the humidity expansion coefficient when the environmental humidity is changed from 5% RH to 90% RH is 0.1 to 1. 0%. The cellulose ester has a degree of substitution of 2.0 ≦ X + Y ≦ 2.9, 0.1 ≦ Y ≦ 0.8 (X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the butyryl group). Satisfy both.

  The reason why the retardation varies due to moisture absorption in the conventional retardation film is estimated as follows. That is, because the cellulose ester has a large number of acyl group carbon atoms, the distance between the resins becomes longer, voids are formed, and it is difficult for water to enter once here, or the carbonyl group present in the acyl substituent of the cellulose acylate resin. It is assumed that the birefringence changes due to the coordination of water molecules.

  In the present embodiment, a cellulose ester (cellulose acetate butyrate) that satisfies the above-described predetermined relationship with respect to the substitution degree X of the acetyl group and the substitution degree Y of the butyryl group is used, and a compound (retardation increasing agent) is mixed with the cellulose ester. As a result, the compound cuts the interaction between the carbonyl group or hydrogen atom of cellulose and water, or the compound is coordinated to the side chain, carbonyl group or hydrogen atom of the cellulose ester. It is considered that retardation fluctuation due to moisture absorption is suppressed. Moreover, in addition to improving the retardation development property of the retardation film even if it is a thin film by mixing a retardation increasing agent with the specific cellulose ester, dimensional fluctuation and retardation fluctuation due to wet heat change are suppressed, It is thought that wet heat durability improves.

  When cellulose acetate butyrate is used as the solute, the amount of the poor solvent (the solvent not having the property of dissolving the cellulose ester) relative to the amount of the good solvent (the solvent having the property of dissolving the cellulose ester) may be relatively increased. it can. Addition of nitrogen-containing heterocyclic compounds when the cellulose ester is cellulose acetate butyrate, because the retardation increasing agent for suppressing fluctuations in retardation due to moisture absorption, that is, nitrogen-containing heterocyclic compounds have good solubility in poor solvents. The amount can be increased. Therefore, it is possible to improve the effect of suppressing retardation fluctuation due to moisture absorption of the retardation film.

  Furthermore, since the humidity expansion coefficient when the environmental humidity is changed from 5% RH to 90% RH is relatively low, the dimensional change of the retardation film exposed to such a change in environmental humidity is also relatively small. Accordingly, it is possible to further suppress retardation fluctuation due to moisture absorption of the retardation film.

  The retardation film preferably contains at least one of a sugar ester and a polycondensed ester. According to this configuration, it is possible to more effectively suppress retardation fluctuation due to moisture absorption of the retardation film, and display quality is improved.

  And the retardation film of the said structure was mounted in the vertical alignment type liquid crystal display device. According to this configuration, in the vertical alignment type liquid crystal display device, it is possible to suppress retardation fluctuations due to moisture absorption of the retardation film, and therefore it is possible to improve changes in color and luminance due to unevenness of the display panel.

  Further, when the retardation film having the above-described structure is formed by a solution casting method, a step of stretching and drying a web formed by casting a resin composition containing a cellulose ester on a metal support (glass) It is desirable to carry out at a drying temperature of a transition temperature Tg-30) ° C. or lower. According to this configuration, it is possible to more effectively suppress retardation fluctuation due to moisture absorption of the retardation film, and display quality is improved.

[Configuration of vertical alignment type liquid crystal display device]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a vertical alignment (VA) liquid crystal display device according to the present embodiment. The vertical alignment type liquid crystal display device 1 includes a liquid crystal display panel 2 and a backlight 3. The backlight 3 is a light source for illuminating the liquid crystal display panel 2.

  The liquid crystal display panel 2 is configured by disposing polarizing plates 5 and 6 on both front and back sides of the liquid crystal cell 4. The liquid crystal cell 4 is formed by sandwiching a liquid crystal layer between a pair of transparent substrates (not shown). As the liquid crystal cell 4, a vertical alignment type liquid crystal cell adopting a color filter on array (COA) method can be used, but the color filter is disposed on a transparent substrate on the viewing side (front side) with respect to the liquid crystal layer. A liquid crystal cell may be used. A polarizing plate 5 is attached to one surface of the viewing side (front surface side) of the liquid crystal cell 4 via an adhesive layer 7. A polarizing plate 6 is attached to one surface of the backlight 3 side (back surface side) of the liquid crystal cell 4 via an adhesive layer 8.

  The polarizing plate 5 includes a polarizer 11 and optical films 12 and 13. The polarizer 11 transmits predetermined linearly polarized light. The optical film 12 is a protective film disposed on the viewing side (surface side) of the polarizer 11. The optical film 13 is disposed on the backlight 3 side (back side) of the polarizer 11.

  The polarizing plate 6 includes a polarizer 14 and optical films 15 and 16. The polarizer 14 transmits predetermined linearly polarized light. The optical film 15 is disposed on the viewing side of the polarizer 14. The optical film 16 is disposed on the backlight 3 side of the polarizer 14. Note that the viewing-side optical film 15 may be omitted, and the polarizer 14 may be in direct contact with the adhesive layer 8. The polarizer 11 and the polarizer 14 are disposed so as to be in a crossed Nicols state.

  The retardation film of this embodiment can be used, for example, as the optical film 13 of the polarizing plate 5 or the optical film 15 of the polarizing plate 6.

[Phase difference film]
The retardation film of this embodiment is a retardation film formed by a solution casting method, and includes a cellulose ester and a nitrogen-containing heterocyclic compound, and the environmental humidity is changed from 5% RH to 90% RH. In this case, the coefficient of humidity expansion is 0.1 to 1.0%. Details of the numerical value of the humidity expansion coefficient will be described in the examples described later.

[Humidity expansion coefficient]
Humidity expansion coefficient is a characteristic related to dimensional stability in the usage environment of the film member. For the measurement of the humidity expansion coefficient, a humidity control TMA (Thermo Mechanical Analysis) capable of evaluating the expansion / contraction of the film member by changing the humidity is used. The humidity expansion coefficient can be adjusted by changing the types and contents of the resins and additives constituting the retardation film.

[Cellulose ester]
The cellulose ester consists of cellulose acetate butyrate. Cellulose acetate butyrate preferably satisfies both the following (1) and (2) when the substitution degree of the acetyl group is X and the substitution degree of the butyryl group is Y. In addition, the measuring method of these substitution degrees can be measured according to ASTM-D817-96.
Formula (1) 2.0 <= X + Y <= 2.9
Formula (2) 0.1 <= Y <= 0.8

  The cellulose ester can be produced by a known method. Examples of cellulose as a raw material for cellulose ester include cotton linter, wood pulp, kenaf and the like, but are not particularly limited thereto. Moreover, the cellulose ester obtained from them can be mixed and used for each arbitrary ratio.

[Retardation raising agent]
The retardation increasing agent of this embodiment is a retardation film in which the retardation value Rth (measurement wavelength 590 nm) in the thickness direction of the retardation film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cellulose ester is not added. The compound which has a function which shows a value 1.1 times or more compared with.

  The retardation increasing agent is not particularly limited. For example, a discotic compound having an aromatic ring described in paragraphs [0143] to [0179] of JP-A-2006-113239, which is well known in the art (1,3 , 5-triazine compounds, etc.), rod-like compounds described in paragraphs [0106] to [0112] of JP-A-2006-113239, paragraphs [0118] to [0133] of JP-A-2012-214682 Pyrimidine compounds, epoxy ester compounds described in paragraphs [0022] to [0028] of JP 2011-140637 A, polyester compounds described in paragraphs [0044] to [0058] of International Publication 2012/014571, etc. Can be used.

  Properties required for the retardation increasing agent include excellent compatibility with the cellulose acetate butyrate resin, excellent retardation when the film is thinned, excellent precipitation resistance, and high humidity. In the bottom, it is excellent in resistance to fluctuations in phase difference value due to the entry and exit of moisture. From such a viewpoint, it is preferable to use the following nitrogen-containing heterocyclic compound as a retardation increasing agent.

[Nitrogen-containing heterocyclic compounds]
The retardation increasing agent of the present embodiment is preferably a nitrogen-containing heterocyclic compound having a structure represented by the following general formula (4).

  The nitrogen-containing heterocyclic compound controls the hydrogen bonding property of the cellulose ester by CH / π interaction with the cellulose ester, and one compound has both the functions of a phase difference increasing agent and a wavelength dispersion adjusting agent. In addition, it has excellent compatibility when combined with a cellulose ester, and there is little generation of fine foreign matters and precipitates during the production process. For example, 1,3,5-triazine-based phase difference increasing agents and the like have a weak CH / π interaction, so they are slightly inferior in compatibility and easily generate foreign matters, and have a high elution property in a saponification solution. It is in.

  CH / π interaction refers to the compatibility of hydrogen bond donating sites such as cellulose esters (for example, hydrogen atoms of hydroxy groups) and hydrogen bond accepting sites (for example, carbonyl oxygen atoms of ester groups) with additives. This is a bond interaction between the hydrogen bonding site present in the main chain or side chain of the resin and the π electron of the aromatic compound of the additive. Due to this CH / π interaction, the compatibility is excellent.

  When the CH / π interaction is formed using the hydrogen bonding site of the resin (CH of cellulose ester) and π of the additive, it is naturally better that the π property of the additive is stronger. There is an index called NICS (Nucleus-Independent Chemical Shift) value as an example that expresses the strength of π property.

  This NICS value is an index used for quantification of aromaticity due to magnetic properties. If the ring is aromatic, the ring center is strongly shielded by the ring current effect, and conversely if the ring is antiaromatic. Anti-shielding (J. Am. Chem. Soc. 1996, 118, 6317). Depending on the magnitude of the NICS value, the strength of the ring current, that is, the degree of contribution of π electrons to the aromaticity of the ring can be determined. Specifically, the NICS value represents the chemical shift (calculated value) of a virtual lithium ion arranged directly at the center of the ring, and the larger the value, the stronger the π property.

  Several reports have been made regarding the measured NICS values. For example, Canadian Journal of Chemistry. , 2004, 82, 50-69 (Document A) and The Journal of Organic Chemistry. , 2000, 67, 1333-1338 (Document B).

  Specifically, a pyrrole ring (-14.87), a thiophene ring (-14.09) furan rather than an aromatic hydrocarbon such as a benzene ring (-7.98) or a naphthalene ring (-8.11). 5-membered aromatic heterocycles such as ring (-12.42), pyrazole ring (-13.82), or imidazole ring (-13.28), triazole ring (-13.18), oxadiazole ring ( -12.44) or a 6-membered aromatic hydrocarbon ring such as a thiazole ring (-12.82) has a larger NICS value (the NICS value is shown in parentheses). By using a compound having such an aromatic 5-membered ring or aromatic 6-membered ring, it is predicted that the CH / π interaction can be strengthened. Among these, a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring is preferable because of its excellent compatibility with the cellulose ester.

  The nitrogen-containing heterocyclic compound according to this embodiment is preferably a nitrogen-containing heterocyclic compound having a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring, and has a structure represented by the following general formula (4). Of the nitrogen heterocyclic compounds, nitrogen-containing heterocyclic compounds having the specific ring structure are preferred. When the compound having the structure represented by the following general formula (4) is used together with cellulose acetate, when the polarizing plate is used in a liquid crystal display device, the occurrence of retardation fluctuation due to environmental humidity fluctuation is suppressed, and contrast reduction and unevenness are observed. Can be suppressed. Furthermore, it functions as a retardation increasing agent showing forward wavelength dispersibility by appropriately adjusting the type and amount of the nitrogen-containing heterocyclic compound.

  From the viewpoint of controlling the affinity with the casting belt, the molecular weight is preferably in the range of 100 to 800, and more preferably in the range of 250 to 450.

[Compound having the structure represented by the general formula (4)]

In the general formula (4), A ₁ , A ₂ and B are each independently an alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl). Group), a cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Among these, an aromatic hydrocarbon ring or an aromatic heterocyclic ring is preferable, and a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring is particularly preferable.

  The structure of the 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring is not limited, but for example, benzene ring, pyrrole ring, pyrazole ring, imidazole ring, 1,2,3-triazole ring, 1,2, Examples include 4-triazole ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxadiazole ring, thiophene ring, thiazole ring, isothiazole ring, thiadiazole ring, isothiadiazole ring and the like.

The 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring represented by A ₁ , A ₂ and B may have a substituent. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group). , 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.), cycloalkenyl group (2-cyclopenten-1-yl). , 2-cyclohexen-1-yl group etc.), alkynyl group (ethynyl group, propargyl group etc.), aromatic hydrocarbon ring group (phenyl group, p-tolyl group, naphthyl group etc.), aromatic heterocyclic group (2 -Pyrrole group, 2-furyl group, 2-thienyl group, pyrrole group, imidazolyl group, oxazolyl group, thiazolyl group, benzoy Dazolyl group, benzoxazolyl group, 2-benzothiazolyl group, pyrazolinone group, pyridyl group, pyridinone group, 2-pyrimidinyl group, triazine group, pyrazole group, 1,2,3-triazole group, 1,2,4-triazole Group, oxazole group, isoxazole group, 1,2,4-oxadiazole group, 1,3,4-oxadiazole group, thiazole group, isothiazole group, 1,2,4-thiodiazole group, 1,3 , 4-thiadiazole group, etc.), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group (methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc. ), Aryloxy group (phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group) 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.), acyloxy group (formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group, etc.), amino Group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.), acylamino group (formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group) Etc.), alkyl and arylsulfonylamino groups (methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group, etc.) , Mercapto group, alkylthio group (such as methylthio group, ethylthio group, n-hexadecylthio group), arylthio group (such as phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group), sulfamoyl group (N-ethylsulfamoyl group) Group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N'-phenylcarbamoyl) sulfamoyl Group), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group, etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octyl) Carbamoyl group, N- (methylsulfonyl) carbamoyl group, etc.) And the like.

In the general formula (4), it is optical that A ₁ , A ₂ and B represent a benzene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring or a 1,2,4-triazole ring. This is preferable because a retardation film having excellent characteristics variation effect and excellent durability can be obtained.

In the general formula (4), T ₁ and T ₂ each independently represents a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring or a 1,2,4-triazole ring. Among these, a pyrazole ring, a triazole ring, or an imidazole ring is preferable because a resin composition that is particularly excellent in retardation fluctuation suppression effect against humidity fluctuation and that has excellent durability is obtained, and is a pyrazole ring. It is particularly preferred. The pyrazole ring, imidazole ring, 1,2,3-triazole ring or 1,2,4-triazole ring represented by T ₁ and T ₂ may be a tautomer. Specific structures of the pyrrole ring, pyrazole ring, imidazole ring, 1,2,3-triazole ring or 1,2,4-triazole ring are shown below.

In the formula, * represents a bonding position with L ₁ , L ₂ , L ₃ or L ₄ in the general formula (4). R ⁵ represents a hydrogen atom or a non-aromatic substituent. Examples of the non-aromatic substituent represented by R ⁵ include the same groups as the non-aromatic substituent among the substituents that A ₁ in the general formula (4) may have. When the substituent represented by R ⁵ is a substituent having an aromatic group, A ₁ and T ₁ or B and T ₁ are easily twisted, and A ₁ , B and T ₁ form an interaction with cellulose acetate. Since it becomes impossible, it is difficult to suppress the fluctuation | variation of an optical characteristic. In order to enhance the effect of suppressing fluctuation in optical properties, R ⁵ is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 5 carbon atoms, and particularly preferably a hydrogen atom. .

In the general formula (4), T ₁ and T ₂ may have a substituent. Examples of the substituent include the same groups as the substituents that A ₁ and A ₂ in the general formula (4) may have.

In the general formula (4), L ₁ , L ₂ , L ₃ and L ₄ each independently represent a single bond or a divalent linking group and represent a 5-membered or 6-membered fragrance via 2 or less atoms. An aromatic hydrocarbon ring or an aromatic heterocycle is linked. “Through 2 or less atoms” represents the minimum number of atoms existing between the connected substituents among the atoms constituting the linking group. The divalent linking group having 2 or less linking atoms is not particularly limited, and includes an alkylene group, an alkenylene group, an alkynylene group, O, (C═O), NR, S, and (O═S═O). It is a divalent linking group selected from the group or a linking group in which two of them are combined. R represents a hydrogen atom or a substituent. Examples of the substituent represented by R include an alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.), a cycloalkyl group (cyclohexyl). Group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), aromatic hydrocarbon ring group (phenyl group, p-tolyl group, naphthyl group, etc.), aromatic heterocyclic group (2-furyl group, 2-thienyl group). , 2-pyrimidinyl group, 2-benzothiazolyl group, 2-pyridyl group, etc.), cyano group and the like. The divalent linking group represented by L ₁ , L ₂ , L ₃ and L ₄ may have a substituent. No particular restriction on the the substituent, but may include the same groups as the substituent that may be possessed by A ₁ and A ₂ in example Formula (4).

In the general formula (4), L ₁ , L ₂ , L _3, and L ₄ represent a compound having a structure represented by the general formula (4), and the planarity of the compound is high, so that Since the interaction becomes strong and fluctuations in optical properties are suppressed, a single bond, or O, (C═O) —O, O— (C═O), (C═O) —NR, or NR— ( C = O) is preferable, and a single bond is more preferable.

In the said General formula (4), n represents the integer of 0-5. When n represents an integer of 2 or more, the plurality of A ₂ , T ₂ , L ₃ and L ₄ in the general formula (4) may be the same or different. The larger n is, the stronger the interaction between the compound having the structure represented by the general formula (4) and the resin that adsorbs water is, so that the effect of suppressing fluctuations in optical properties is better. Excellent compatibility with resin that adsorbs. For this reason, n is preferably an integer of 1 to 3, and more preferably an integer of 1 or 2.

[Compound having structure represented by general formula (5)]
The compound having a structure represented by the general formula (4) is preferably a compound having a structure represented by the general formula (5).

（式中、Ａ₁、Ａ₂、Ｔ₁、Ｔ₂、Ｌ₁、Ｌ₂、Ｌ₃及びＬ₄はそれぞれ前記一般式（４）におけるＡ₁、Ａ₂、Ｔ₁、Ｔ₂、Ｌ₁、Ｌ₂、Ｌ₃及びＬ₄と同義である。Ａ₃及びＴ₃はそれぞれ前記一般式（４）におけるＡ₁及びＴ₁と同様の基を表す。Ｌ₅及びＬ₆は前記一般式（４）におけるＬ₁と同様の基を表す。ｍは０〜４の整数を表す。）

(In the formula, A ₁ , A ₂ , T ₁ , T ₂ , L ₁ , L ₂ , L ₃ and L ₄ are respectively A ₁ , A ₂ , T ₁ , T ₂ , L ₁ in the general formula (4). , L ₂ , L ₃ and L ₄ , A ₃ and T ₃ represent the same groups as A ₁ and T ₁ in the general formula (4), respectively, and L ₅ and L ₆ represent the general formula ( 4) represents the same group as L _{1 in} m. M represents an integer of 0 to 4.)

  Since the smaller m is more compatible with cellulose acetate, m is preferably an integer of 0 to 2, more preferably an integer of 0 or 1.

[Compound having the structure represented by the general formula (6)]
The compound having a structure represented by the general formula (4) is preferably a triazole compound having a structure represented by the following general formula (6).

（式中、Ａ₁、Ｂ、Ｌ₁及びＬ₂は上記一般式（４）におけるＡ₁、Ｂ、Ｌ₁及びＬ₂と同様の基を表す。ｋは１〜４の整数を表す。Ｔ₁は１，２，４−トリアゾール環を表す。）

(.T wherein, A _1, B, the .k where L ₁ and L ₂ represents a A _1, B, the same group as L ₁ and L ₂ in formula (4) represents an integer of 1 to 4 ₁ represents a 1,2,4-triazole ring.)

  Furthermore, the triazole compound having a structure represented by the general formula (6) is preferably a triazole compound having a structure represented by the following general formula (7).

（式中、Ｚは下記一般式（８）の構造を表す。ｑは２または３の整数を表す。少なくとも二つのＺはベンゼン環に置換された少なくとも一つのＺに対してオルト位またはメタ位に結合する。）

(In the formula, Z represents the structure of the following general formula (8). Q represents an integer of 2 or 3. At least two Z are ortho-position or meta-position with respect to at least one Z substituted on the benzene ring. To join.)

（式中、Ｒ¹⁰は水素原子、アルキル基またはアルコキシ基を表す。ｐは１〜５の整数を表す。＊はベンゼン環との結合位置を表す。Ｔ₁は１，２，４−トリアゾール環を表す。）

(Wherein R ¹⁰ represents a hydrogen atom, an alkyl group or an alkoxy group. P represents an integer of 1 to 5. * represents a bonding position with a benzene ring. T ₁ represents a 1,2,4-triazole ring. Represents.)

  The compound having the structure represented by the general formula (4), (5), (6) or (7) may form a hydrate, a solvate or a salt. In this embodiment, the hydrate may contain an organic solvent, and the solvate may contain water. That is, “hydrate” and “solvate” include mixed solvates containing both water and organic solvents. Salts include acid addition salts formed with inorganic or organic acids. Examples of inorganic acids include, but are not limited to, hydrohalic acids (hydrochloric acid, hydrobromic acid, etc.), sulfuric acid, phosphoric acid and the like. Examples of organic acids include acetic acid, trifluoroacetic acid, propionic acid, butyric acid, oxalic acid, citric acid, benzoic acid, alkylsulfonic acid (such as methanesulfonic acid), allylsulfonic acid (benzenesulfonic acid, 4-toluenesulfone) Acid, 1,5-naphthalenedisulfonic acid, etc.) and the like. Of these, hydrochloride, acetate, propionate and butyrate are preferable.

  Examples of salts are those wherein the acidic moiety present in the parent compound is a metal ion (eg, an alkali metal salt, such as a sodium or potassium salt, an alkaline earth metal salt, such as a calcium or magnesium salt, an ammonium salt, an alkali metal ion, an alkaline earth metal And salts formed when substituted with organic bases (ethanolamine, diethanolamine, triethanolamine, morpholine, piperidine, etc.). Not. Of these, sodium salts and potassium salts are preferred.

  Examples of the solvent included in the solvate include any common organic solvent. Specifically, alcohol (eg, methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, t-butanol), ester (eg, ethyl acetate), hydrocarbon (eg, toluene, hexane, Heptane), ether (eg, tetrahydrofuran), nitrile (eg, acetonitrile), ketone (acetone) and the like. Preferably, it is a solvate of alcohol (eg, methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, t-butanol). These solvents may be reaction solvents used in the synthesis of the compound, may be used in crystallization purification after the synthesis, or may be a mixture thereof.

  Two or more kinds of solvents may be included at the same time, or a form including water and a solvent (for example, water and alcohol (for example, methanol, ethanol, t-butanol, etc.)) may be used.

  Even when the compound having the structure represented by the general formula (4), (5), (6) or (7) is added in a form not containing water, a solvent, or a salt, Hydrates, solvates or salts may be formed in the retardation film.

  The molecular weight of the compound having the structure represented by the general formula (4), (5), (6) or (7) is not particularly limited. However, the smaller the compound, the better the compatibility with the resin. Since the effect of suppressing the fluctuation of the optical value with respect to the change is high, it is preferably 150 to 2000, more preferably 200 to 1500, and more preferably 300 to 1000.

  Furthermore, the nitrogen-containing heterocyclic compound according to this embodiment is particularly preferably a compound having a structure represented by the following general formula (3).

（式中、Ａはピラゾール環を表し、Ａｒ₁及びＡｒ₂はそれぞれ芳香族炭化水素環または芳香族複素環を表し、置換基を有しても良い。Ｒ₁は水素原子、アルキル基、アシル基、スルホニル基、アルキルオキシカルボニル基またはアリールオキシカルボニル基を表す。ｑは１または２の整数を表し、ｎ及びｍは１〜３の整数を表す。）

(In the formula, A represents a pyrazole ring, Ar ₁ and Ar ₂ each represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and may have a substituent. R ₁ represents a hydrogen atom, an alkyl group, an acyl group; A group, a sulfonyl group, an alkyloxycarbonyl group or an aryloxycarbonyl group, q represents an integer of 1 or 2, and n and m represent an integer of 1 to 3)

The aromatic hydrocarbon ring or aromatic heterocyclic ring represented by Ar ₁ and Ar ₂ is preferably the 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring mentioned in the general formula (4), respectively. . Examples of the substituent for Ar ₁ and Ar ₂ include the same substituents as those shown for the compound having the structure represented by the general formula (4).

Specific examples of R ₁ include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group). , 2-ethylhexyl group etc.), acyl group (acetyl group, pivaloylbenzoyl group etc.), sulfonyl group (eg methylsulfonyl group, ethylsulfonyl group etc.), alkyloxycarbonyl group (eg methoxycarbonyl group), aryloxycarbonyl Group (for example, phenoxycarbonyl group and the like) and the like.

  q represents an integer of 1 or 2, and n and m represent an integer of 1 to 3.

  Specific examples of the compound having a 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle used in this embodiment are described in paragraphs [0140] to [0214] of International Publication No. 2014/109350. Yes. Especially, the compound which has a structure represented by the said General formula (4), (5), (6), (7) is preferable, and it is more preferable that it is a compound which has a structure represented by General formula (3). . The compounds having the 5-membered or 6-membered aromatic hydrocarbon ring or aromatic heterocycle that can be used in this embodiment are described in paragraphs [0140] to [0214] of the above-mentioned International Publication No. 2014/109350. There is no limitation by the specific examples described. Further, as described above, the above specific examples may be tautomers and may form hydrates, solvates or salts.

  Next, a method for synthesizing the compound having the structure represented by the general formula (4) will be described.

  The compound having the structure represented by the general formula (4) can be synthesized by a known method. In the compound having the structure represented by the general formula (4), any raw material may be used as the compound having a 1,2,4-triazole ring, but the nitrile derivative or imino ether derivative is reacted with the hydrazide derivative. The method of making it preferable is. The solvent used in the reaction may be any solvent as long as it does not react with the raw material, but may be an ester type (for example, ethyl acetate, methyl acetate, etc.), an amide type (dimethylformamide, dimethylacetamide, etc.), an ether type (ethylene glycol) Dimethyl ether), alcohols (for example, methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, ethylene glycol, ethylene glycol monomethyl ether, etc.), aromatic hydrocarbons (for example, toluene, xylene, etc.), water Can be done. The solvent to be used is preferably an alcohol solvent. These solvents may be used in combination.

  Although there is no restriction | limiting in particular in the usage-amount of a solvent, It is preferable that it exists in the range of 0.5-30 times amount with respect to the mass of the hydrazide derivative to be used, More preferably, it is 1.0-25 times amount, Especially preferably, it exists in the range of 3.0-20 times amount.

  When reacting a nitrile derivative and a hydrazide derivative, it is not necessary to use a catalyst, but it is preferable to use a catalyst in order to accelerate the reaction. As a catalyst to be used, an acid or a base may be used. Examples of the acid include hydrochloric acid, sulfuric acid, nitric acid, acetic acid and the like, and hydrochloric acid is preferable. The acid may be added after diluted in water, or may be added by a method of blowing a gas into the system. Bases include inorganic bases (potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium hydroxide, sodium hydroxide, etc.) and organic bases (sodium methylate, sodium ethylate, potassium methylate, potassium ethylate, sodium Any of butyrate, potassium butyrate, diisopropylethylamine, N, N′-dimethylaminopyridine, 1,4-diazabicyclo [2.2.2] octane, N-methylmorpholine, imidazole, N-methylimidazole, pyridine, etc.) May be used. The inorganic base is preferably potassium carbonate, and the organic base is preferably sodium ethylate, sodium ethylate, or sodium butyrate. The inorganic base may be added as a powder or may be added in a state dispersed in a solvent. The organic base may be added in a state dissolved in a solvent (for example, a 28% methanol solution of sodium methylate).

  The amount of the catalyst used is not particularly limited as long as the reaction proceeds, but it is preferably in the range of 1.0 to 5.0 moles relative to the triazole ring to be formed, and more preferably 1.05 to 3.0. Within the range of double moles is preferred.

  When the imino ether derivative and the hydrazide derivative are reacted, it is not necessary to use a catalyst, and the target product can be obtained by heating in a solvent.

  There are no particular restrictions on the method of adding the raw material, solvent and catalyst used in the reaction, and the catalyst may be added last, or the solvent may be added last. Also preferred is a method of dispersing or dissolving a nitrile derivative in a solvent, adding a catalyst, and then adding a hydrazide derivative.

  The solution temperature during the reaction may be any temperature as long as the reaction proceeds, but is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 140 ° C. Moreover, you may react, removing the water to produce | generate.

  Any means for treating the reaction solution may be used, but when a base is used as a catalyst, a method of neutralizing the reaction solution by adding an acid is preferable. Examples of the acid used for neutralization include hydrochloric acid, sulfuric acid, nitric acid and acetic acid, with acetic acid being particularly preferred. The amount of the acid used for neutralization is not particularly limited as long as the pH of the reaction solution is in the range of 4 to 9, but it is preferably 0.1 to 3 times mol, particularly preferably 0. It is in the range of 2-1.5 times mole.

  As a method for treating the reaction solution, when extracting using a suitable organic solvent, a method of washing the organic solvent with water after extraction and then concentrating is preferable. The appropriate organic solvent mentioned here is a water-insoluble solvent such as ethyl acetate, toluene, dichloromethane, ether, or a mixed solvent of the water-insoluble solvent and tetrahydrofuran or an alcohol solvent, preferably ethyl acetate. It is.

  When the compound having the structure represented by the general formula (4) is crystallized, there is no particular limitation, but a method of adding water to the neutralized reaction solution to crystallize, or the general formula (4) A method of crystallization by neutralizing an aqueous solution in which a compound having the structure represented is dissolved is preferable.

[Synthesis of Exemplified Compound 1]
For example, Exemplary Compound 1 can be synthesized by the following scheme.

  To 350 ml of n-butanol, 77.3 g (75.0 mmol) of benzonitrile, 34.0 g (25.0 mmol) of benzoylhydrazine and 107.0 g (77.4 mmol) of potassium carbonate were added, and the reaction was performed at 120 ° C. for 24 hours under a nitrogen atmosphere. Stir. The reaction solution was cooled to room temperature, the precipitate was filtered, and the filtrate was concentrated under reduced pressure. 20 ml of isopropanol was added to the concentrate, and the precipitate was collected by filtration. The precipitate collected by filtration was dissolved in 80 ml of methanol, 300 ml of pure water was added, and acetic acid was added dropwise until the pH of the solution reached 7. The precipitated crystals were collected by filtration, washed with pure water, and blown and dried at 50 ° C. to obtain 38.6 g of Exemplified Compound 1. The yield was 70% based on benzoylhydrazine.

The ¹ H-NMR spectrum of the obtained exemplary compound 1 is as follows.

¹ H-NMR (400 MHz, solvent: heavy DMSO, standard: tetramethylsilane) δ (ppm): 7.56 to 7.48 (6H, m), 7.62 to 7.61 (4H, m)

[Synthesis of Exemplified Compound 6]
Exemplary compound 6 can be synthesized by the following scheme.

  To 40 ml of n-butanol, 2.5 g (19.5 mmol) of 1,3-dicyanobenzene, 7.9 g (58.5 mmol) of benzoylhydrazine and 9.0 g (68.3 mmol) of potassium carbonate were added, and the temperature was 120 ° C. under a nitrogen atmosphere. For 24 hours. After cooling the reaction solution, 40 ml of pure water was added and the mixture was stirred at room temperature for 3 hours, and then the precipitated solid was separated by filtration and washed with pure water. Water and ethyl acetate were added to the obtained solid for liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The resulting crude crystals were purified by silica gel chromatography (ethyl acetate / heptane) to obtain 5.5 g of exemplary compound 6. The yield was 77% based on 1,3-dicyanobenzene.

The ¹ H-NMR spectrum of Exemplified Compound 6 obtained is as follows.

¹ H-NMR (400 MHz, solvent: heavy DMSO, standard: tetramethylsilane) δ (ppm): 8.83 (1H, s), 8.16-8.11 (6H, m), 7.67-7 .54 (7H, m)

[Synthesis of Exemplary Compound 176]
Exemplary compound 176 can be synthesized according to the following scheme.

  To 520 ml of dehydrated tetrahydrofuran was added 80 g (0.67 mol) of acetophenone and 52 g (0.27 mol) of dimethyl isophthalate. . After stirring for 3 hours under ice-water cooling, the mixture was stirred for 12 hours under water-cooling. Concentrated sulfuric acid was added to the reaction solution for neutralization, and then pure water and ethyl acetate were added for liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. 55.2 g of intermediate A was obtained by adding methanol to the obtained crude crystal and suspending and washing it.

  Intermediate A 55 g (0.15 mol) was added to tetrahydrofuran 300 ml and ethanol 200 ml, and 18.6 g (0.37 mol) of hydrazine monohydrate was added dropwise little by little while stirring at room temperature. After completion of dropping, the mixture was heated to reflux for 12 hours. Pure water and ethyl acetate were added to the reaction solution for liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The obtained crude crystals were purified by silica gel chromatography (ethyl acetate / heptane) to obtain 27 g of Exemplified Compound 176.

The ¹ H-NMR spectrum of the obtained exemplary compound 176 is as follows. In order to avoid complication of chemical shift due to the presence of tautomers, the measurement was performed by adding a few drops of trifluoroacetic acid to the measurement solvent.

¹ H-NMR (400 MHz, solvent: heavy DMSO, standard: tetramethylsilane) δ (ppm): 8.34 (1H, s), 7.87-7.81 (6H, m), 7.55-7 .51 (1H, m), 7.48-7.44 (4H, m), 7.36-7.33 (2H, m), 7.29 (1H, s)

  Other compounds can be synthesized by the same method.

[About the usage method of the compound which has a structure represented by General formula (3)-(5)]
The compound having the structure represented by the general formulas (3) to (5) according to the present embodiment can be appropriately adjusted and contained in the retardation film, but the addition amount is in the retardation film. 0.1 to 10% by mass, preferably 1 to 5% by mass, and more preferably 2 to 5% by mass. The addition amount varies depending on the type of cellulose acetate and the type of the compound, but the optimum value can be determined by the addition amount at which the retardation film of the present embodiment exhibits a desired retardation value. If it is in this range, the fluctuation | variation of the retardation depending on the change of environmental humidity can be reduced, without impairing the mechanical strength of the retardation film of this embodiment.

  The compound having the structure represented by the general formulas (3) to (5) may be added as a powder to the resin forming the retardation film, and after dissolving in the solvent, the retardation is added. You may add to resin which forms a film.

<Other retardation increasing agents>
In the present embodiment, in addition to the above-described compounds, compounds disclosed in the following known documents can also be used as retardation increasing agents. For example, Japanese Patent No. 5156067, Japanese Patent No. 3896404, Japanese Patent No. 4076454, Japanese Patent No. 4234823, Japanese Patent Application Laid-Open No. 2012-82235, Korean Published Patent No. 2011-0075492, Korean Published Patent No. 2011- It is also possible to use compounds disclosed in Korean Patent No. 0037289, Korean Patent No. 10-2011-0075473, Korean Patent No. 2011-0075199, Korean Patent No. 2011-0071493 as a retardation increasing agent. It is.

[Other additives]
The retardation film of the present embodiment preferably contains other additives, and examples thereof include a plasticizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, and a release agent. The compound used more effectively preferably contains a plasticizer, and among them, a sugar ester described below, or a polycondensed ester containing a repeating unit obtained by reacting a dicarboxylic acid and a diol is used. , Excellent compatibility with cellulose ester, control of moisture in / out of high humidity to reduce phase difference fluctuation, and control saponification liquid penetration into saponification solution To preferred.

[Plasticizer]
<Sugar ester>
The sugar ester used in the retardation film of the present embodiment is a sugar ester having at least one pyranose ring or furanose ring of 1 to 12 and esterifying all or part of the OH groups of the structure. Preferably there is. The sugar ester according to this embodiment is preferably added for the purpose of preventing hydrolysis.

  The sugar ester according to this embodiment is a compound containing at least one of a furanose ring and a pyranose ring, and may be a monosaccharide or a polysaccharide having 2 to 12 sugar structures linked together. The sugar ester is preferably a compound in which at least one OH group of the sugar structure is esterified. In the sugar ester according to this embodiment, the average ester substitution degree is preferably in the range of 4.0 to 8.0, and more preferably in the range of 5.0 to 7.5.

  Particularly preferred sugar esters in the present embodiment include sugar esters represented by the following general formula (A).

Formula _{(A) (HO) m -G-} (O-C (= O) -R 2) n

In the above general formula (A), G represents a monosaccharide or disaccharide residue, and R ² represents an aliphatic group or an aromatic group. m is the sum of the number of hydroxy groups directly bonded to the monosaccharide or disaccharide residue, and n is directly bonded to the monosaccharide or disaccharide residue-(O-C (= O) -R ² ) Total number of groups, 3 ≦ m + n ≦ 8, and n ≠ 0.

The sugar ester having the structure represented by the general formula (A) is a single compound in which the number (m) of hydroxy groups and the number (n) of — (O—C (═O) —R ² ) groups are fixed. It is known that it becomes a compound in which several components having different m and n in the formula are mixed. Therefore, the performance as a mixture in which the number (m) of hydroxy groups and the number (n) of — (O—C (═O) —R ² ) groups are changed is important, and the retardation film of the present embodiment In that case, sugar esters having an average ester substitution degree in the range of 5.0 to 7.5 are preferred.

  In the above general formula (A), G represents a monosaccharide or disaccharide residue. Specific examples of monosaccharides include allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, lyxose, and the like.

  Although the specific example of the compound which has the monosaccharide residue of the sugar ester represented with general formula (A) below is shown, this embodiment is not limited to these illustrated compounds.

  Specific examples of the disaccharide residue include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and isotrehalose.

  Although the specific example of the compound which has the disaccharide residue of the sugar ester represented with general formula (A) below is shown, this embodiment is not limited to these illustrated compounds.

In the general formula (A), R ² represents an aliphatic group or an aromatic group. Here, the aliphatic group and the aromatic group may each independently have a substituent.

In the general formula (A), m is the total number of hydroxy groups directly bonded to monosaccharide or disaccharide residues, and n is directly bonded to monosaccharide or disaccharide residues. It is the total number of — (O—C (═O) —R ² ) groups. Further, it is necessary that 3 ≦ m + n ≦ 8, and it is preferable that 4 ≦ m + n ≦ 8. Further, n ≠ 0. When n is 2 or more, the — (O—C (═O) —R ² ) groups may be the same as or different from each other.

The aliphatic group in the definition of R ² may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 1 to 20 carbon atoms. 2 to 15 are particularly preferable. Specific examples of the aliphatic group include, for example, methyl, ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, iso-butyl, tert-butyl, amyl, iso-amyl, tert-amyl, and n-hexyl. , Cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, tert-octyl, dodecyl, hexadecyl, octadecyl, didecyl and the like.

Further, the aromatic group in the definition of R ² 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 rings such as benzene, naphthalene, anthracene, biphenyl, and terphenyl. As the aromatic hydrocarbon group, a benzene ring, a naphthalene ring, and a biphenyl ring are particularly preferable. The aromatic heterocyclic group is preferably a ring containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom. 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, isoquinoline. , Phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. As the aromatic heterocyclic group, a pyridine ring, a triazine ring, and a quinoline ring are particularly preferable.

  Next, although the preferable example of the sugar ester represented by general formula (A) is shown below, this embodiment is not limited to these illustrated compounds.

  A sugar ester may contain two or more different substituents in one molecule, can contain an aromatic substituent and an aliphatic substituent in one molecule, and can contain two or more different aromatics. A group substituent can be contained in one molecule, and two or more different aliphatic substituents can be contained in one molecule.

  It is also preferable to contain a mixture of two or more sugar esters. It is also preferable to simultaneously contain a sugar ester containing an aromatic substituent and a sugar ester containing an aliphatic substituent.

<Synthesis Example: Synthesis Example of Sugar Ester Represented by Formula (A)>
Below, an example of the synthesis | combination of the sugar ester which can be used suitably for this embodiment is shown.

Four-headed Kolben equipped with a stirrer, reflux condenser, thermometer and nitrogen gas inlet tube, 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, pyridine 379.7 g (4.8 mol) of each were charged, and the temperature was raised while bubbling nitrogen gas from a nitrogen gas inlet tube under stirring, and esterification was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass sodium carbonate aqueous solution were added, and the mixture was stirred at 50 ° C. for 30 minutes, and then allowed to stand to separate a toluene layer. Finally, 100 g of water was added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer was collected, and toluene was distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). A mixture of compounds A-1, A-2, A-3, A-4 and A-5 was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 7% by mass, A-2 was 58% by mass, A-3 was 23% by mass, A-4 was 9% by mass, A-5. Was 3% by mass, and the average ester substitution degree of the sugar ester was 6.57. A part of the obtained mixture was purified by silica gel column chromatography to obtain A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively.

  The addition amount of the sugar ester is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass with respect to the cellulose ester.

<Polycondensed ester>
As the polycondensation ester used in the retardation film of the present embodiment, it is preferable to use a polycondensation ester having a structure represented by the following general formula (9).

  The polycondensation ester is preferably contained in the range of 1 to 30% by mass and more preferably in the range of 5 to 20% by mass in the retardation film of the present embodiment because of its plastic effect.

Formula _{(9) B 3 - (G} 2 -A) n -G 2 -B 4

In the general formula (9), B ₃ and B ₄ each independently represents an aliphatic or aromatic monocarboxylic acid residue or a hydroxy group. G ₂ represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms. n represents an integer of 1 or more.

The polycondensed ester of this embodiment is a polycondensed ester containing a repeating unit obtained by reacting a dicarboxylic acid and a diol, A represents a carboxylic acid residue in the polycondensed ester, and G ₂ represents an alcohol residue. .

  The dicarboxylic acid constituting the polycondensed ester is an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid, preferably an aromatic dicarboxylic acid. The dicarboxylic acid may be one type or a mixture of two or more types. In particular, it is preferable to mix aromatic and aliphatic.

  The diol constituting the polycondensed ester is an aromatic diol, an aliphatic diol or an alicyclic diol, preferably an aliphatic diol, more preferably a diol having 1 to 4 carbon atoms. The diol may be one type or a mixture of two or more types.

  Among these, it is preferable to include a repeating unit obtained by reacting at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a diol having 1 to 8 carbon atoms, and a dicarboxylic acid containing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. And a repeating unit obtained by reacting a diol having 1 to 8 carbon atoms.

  Both ends of the molecule of the polycondensed ester may be sealed or may not be sealed.

  Specific examples of the alkylene dicarboxylic acid constituting A in the general formula (9) include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1,4-butanedicarboxylic acid ( Divalent groups derived from adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like are included. Specific examples of the alkenylene dicarboxylic acid constituting A include maleic acid and fumaric acid. Specific examples of the aryl dicarboxylic acid constituting A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and the like. It is done.

  A may be one type, or two or more types may be combined. Among these, A is preferably a combination of an alkylene dicarboxylic acid having 4 to 12 carbon atoms and an aryl dicarboxylic acid having 8 to 12 carbon atoms.

G ₂ in the general formula (9) is a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, a divalent group derived from an aryl glycol having 6 to 12 carbon atoms, or 4 carbon atoms. Represents a divalent group derived from ˜12 oxyalkylene glycols.

Examples of the divalent group derived from an alkylene glycol having 2 to 12 carbon atoms in G ₂ include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 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 Is included.

Examples of divalent groups derived from aryl glycols having 6 to 12 carbon atoms in G ₂ include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene. Divalent groups derived from (hydroquinone) and the like are included. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are 2 derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Valent groups are included.

One type of G ₂ may be used, or two or more types may be combined. Among these, G ₂ is preferably a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, more preferably 2 to 5, and most preferably 2 to 4.

B ₃ and B ₄ in the general formula (9) are each a monovalent group or a hydroxy group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

  An aromatic ring-containing monocarboxylic acid in a monovalent group derived from an aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, and not only those in which the aromatic ring is directly bonded to a carboxy group, but also aromatic Also included are those in which a ring is bonded to a carboxy group via an alkylene group or the like. Examples of monovalent groups derived from aromatic ring-containing monocarboxylic acids include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, normal propyl benzoic acid, Monovalent groups derived from aminobenzoic acid, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid and the like are included. Of these, benzoic acid and p-toluic acid are preferable.

  Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. A group is included. Among these, a monovalent group derived from an alkyl monocarboxylic acid having 1 to 3 carbon atoms in the alkyl portion is preferable, and an acetyl group (a monovalent group derived from acetic acid) is more preferable.

  The weight average molecular weight of the polycondensed ester according to the present invention is preferably in the range of 500 to 3,000, and more preferably in the range of 600 to 2,000. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

  Hereinafter, although the specific example of the polycondensation ester which has a structure represented by General formula (9) is shown, it is not limited to this.

  Hereinafter, a specific synthesis example of the polycondensed ester described above will be described.

(Polycondensed ester P1)
180 g of ethylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a quick cooling tube. The temperature is gradually raised with stirring until reaching 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P1. The acid value was 0.20 and the number average molecular weight was 450.

(Polycondensed ester P2)
251 g of 1,2-propylene glycol, 103 g of phthalic anhydride, 244 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, stirrer, and quick cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off at 200 ° C. under reduced pressure to obtain the following polycondensed ester P2. The acid value was 0.10 and the number average molecular weight was 450.

(Polycondensed ester P3)
330 g of 1,4-butanediol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 4 L of 2 L equipped with a thermometer, a stirrer, and a slow cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,4-butanediol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P3. The acid value was 0.50 and the number average molecular weight was 2000.

(Polycondensed ester P4)
251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a quick cooling tube, The temperature is gradually raised with stirring until it reaches 230 ° C. in an air stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P4. The acid value was 0.10 and the number average molecular weight was 400.

(Polycondensed ester P5)
251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-troyl acid and 0.191 g of tetraisopropyl titanate as an esterification catalyst are charged into a 2 L four-necked flask equipped with a thermometer, a stirrer and a slow cooling tube. The temperature is gradually raised with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off at 200 ° C. under reduced pressure to obtain the following polycondensed ester P5. The acid value was 0.30 and the number average molecular weight was 400.

(Polycondensed ester P6)
180 g of 1,2-propylene glycol, 292 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube, in a nitrogen stream. The temperature is gradually raised while stirring until 200 ° C is reached. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P6. The acid value was 0.10 and the number average molecular weight was 400.

(Polycondensed ester P7)
180 g of 1,2-propylene glycol, 244 g of phthalic anhydride, 103 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst are charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube. The temperature is gradually raised with stirring until it reaches 200 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P7. The acid value was 0.10 and the number average molecular weight was 320.

(Polycondensed ester P8)
251 g of ethylene glycol, 244 g of phthalic anhydride, 120 g of succinic acid, 150 g of acetic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a slow cooling tube, and nitrogen The temperature is gradually raised with stirring until it reaches 200 ° C. in an air stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted ethylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P8. The acid value was 0.50 and the number average molecular weight was 1200.

(Polycondensed ester P9)
In the same production method as in the polycondensation ester P2, the reaction conditions were changed to obtain a polycondensation ester P9 having an acid value of 0.10 and a number average molecular weight of 315.

<Other plasticizers>
Examples of other plasticizers include polyhydric alcohol esters, polyhydric carboxylic acid esters (including phthalic acid esters), glycolate compounds, fatty acid esters, and phosphoric acid esters. These may be used alone or in combination of two or more.

  The polyhydric alcohol ester is an ester (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a 2-20 valent aliphatic polyhydric alcohol ester. The polyhydric alcohol ester preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  Preferred examples of the aliphatic polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, and 1,2-butane. Diol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, Pentaerythritol, trimethylolethane, xylitol and the like are included. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol and the like are preferable.

  The monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, an aromatic monocarboxylic acid, or the like. In order to increase the moisture permeability of the film and make it less likely to volatilize, alicyclic monocarboxylic acids or aromatic monocarboxylic acids are preferred. One kind of monocarboxylic acid may be used, or a mixture of two or more kinds may be used. Further, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  The aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is more preferably 1-20, and still more preferably 1-10. Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; undecylenic acid, olein Examples include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Of these, acetic acid or a mixture of acetic acid and other monocarboxylic acid is preferable in order to enhance the compatibility with cellulose acetate.

  Examples of the alicyclic monocarboxylic acid include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid and the like.

  Examples of aromatic monocarboxylic acids include benzoic acid; benzoic acid having benzene ring introduced with 1 to 3 alkyl groups or alkoxy groups (for example, methoxy group or ethoxy group) (for example, toluic acid); Aromatic monocarboxylic acids having two or more (for example, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, etc.) are included, and benzoic acid is preferred.

  Specific examples of the polyhydric alcohol ester include compounds described in paragraphs [0058] to [0061] of JP-A-2006-113239.

  The polyvalent carboxylic acid ester is an ester of a divalent or higher, preferably 2 to 20 valent polyvalent carboxylic acid and an alcohol compound. The polyvalent carboxylic acid is preferably a 2-20 valent aliphatic polyvalent carboxylic acid, or a 3-20 valent aromatic polyvalent carboxylic acid or a 3-20 valent alicyclic polyvalent carboxylic acid.

  Examples of polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, Contains aliphatic polycarboxylic acids such as fumaric acid, maleic acid and tetrahydrophthalic acid, oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid, etc. to suppress volatilization from the film Is preferably an oxypolycarboxylic acid.

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

  The molecular weight of the polyvalent carboxylic acid ester is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The molecular weight of the polycarboxylic acid ester plasticizer is preferably large from the viewpoint of suppressing bleed out, and is preferably small from the viewpoint of moisture permeability and compatibility with cellulose acetate.

  Examples of polyvalent carboxylic acid esters include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, Examples include dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, and tetrabutyl pyromellitic acid.

  The polyvalent carboxylic acid ester may be a phthalic acid ester. Examples of the phthalic acid ester include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

  Examples of glycolate compounds include alkylphthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Rikoreto and the like, preferably ethyl phthalyl ethyl glycolate.

  Esters include fatty acid esters, citrate esters, phosphate esters, and the like.

  Examples of fatty acid esters include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of the citrate ester include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like, and preferably triphenyl phosphate.

  Of these, polyesters, glycolate compounds, and phosphate esters are preferable, and polyesters are particularly preferable.

  The content of the plasticizer is preferably in the range of 1 to 20% by mass and more preferably in the range of 1.5 to 15% by mass with respect to the cellulose ester. When the content of the plasticizer is within the above range, an effect of imparting plasticity can be exhibited, and the plasticizer is also excellent in resistance to bleeding.

[Antioxidant]
Antioxidants are also called deterioration inhibitors. When a liquid crystal image display device or the like is placed in a high humidity and high temperature environment, the retardation film may be deteriorated.

  The antioxidant has a role of delaying or preventing the retardation film from being decomposed by, for example, a residual solvent amount of halogen in the retardation film, phosphoric acid of a phosphoric acid plasticizer, or the like. Thereby, it is preferable to contain antioxidant in retardation film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1, 3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadec -3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) ) -Isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination.

  The amount of these compounds to be added is preferably in the range of 1 ppm to 1.0%, more preferably in the range of 10 to 1000 ppm by mass ratio with respect to the cellulose ester.

[Ultraviolet absorber]
The retardation film of this embodiment can contain an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function.

  Although it does not specifically limit as an ultraviolet absorber, For example, ultraviolet absorbers, such as a benzotriazole type, 2-hydroxybenzophenone type, or a salicylic acid phenyl ester type, are mentioned. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone Benzophenones such as

  Among UV absorbers, UV absorbers with a molecular weight of 400 or more are difficult to sublimate or volatilize at a high boiling point, and are difficult to disperse even when the film is dried at high temperature. It is preferable from the viewpoint of improving weather resistance.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1 , 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis Hindered amines such as (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and further 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalon Acid bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy ] Hindered phenol and hindered amine in the molecule such as ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine The thing of the hybrid type | system | group which has these structures is mentioned, These can be used individually or in combination of 2 or more types. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

  Commercially available products may be used as these UV absorbers, for example, Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. manufactured by BASF Japan, or 2,2 ′ -Methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; LA31 made by ADEKA Corporation as an example of a commercial product) Can be preferably used.

  The said ultraviolet absorber can be used individually by 1 type or in combination of 2 or more types.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, the operating conditions, etc., but is generally in the range of 0.05 to 10% by weight, preferably 0.1 to 5% by weight, based on cellulose acetate. Is added.

  The method of adding the UV absorber may be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof. Or you may add directly in dope composition.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or sand mill is used in the organic solvent and cellulose acetate to disperse and then added to the dope.

[Fine particles (matting agent)]
The retardation film of this embodiment may further contain fine particles (matting agent) as necessary in order to improve the slipperiness of the surface.

  The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Examples include magnesium acid and calcium phosphate. Among these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.

  Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Seahoster KE-P10, KE-P30, KE -P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like. Of these, Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because they reduce the coefficient of friction while keeping the turbidity of the resulting film low.

  The primary particle diameter of the fine particles is preferably in the range of 5 to 50 nm, more preferably in the range of 7 to 20 nm. A larger primary particle size has a larger effect of increasing the slipperiness of the resulting film, but transparency tends to be lowered. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter in the range of 0.05 to 0.3 μm. The size of the primary particles or the secondary aggregates of the fine particles is observed with a transmission electron microscope at a magnification of 500,000 to 2,000,000 times, and the primary particles or secondary aggregates are observed, and 100 particles of primary particles or secondary aggregates are observed. It can obtain | require as an average value of a diameter.

  The content of the fine particles is preferably in the range of 0.05 to 1.0 mass%, more preferably in the range of 0.1 to 0.8 mass% with respect to the cellulose ester.

[Method for producing retardation film]
The retardation film of this embodiment can be produced by a solution casting method.

[Solution casting method]
Hereinafter, the example which manufactures the phase difference film of this embodiment with a solution casting method is demonstrated. FIG. 2 is a cross-sectional view illustrating a schematic configuration of the retardation film manufacturing apparatus according to the present embodiment.

  In the production of the retardation film of this embodiment, at least cellulose acetate and a retardation increasing agent are dissolved in a solvent to prepare a dope, and the dope is filtered. The prepared dope is cast on a belt-shaped or drum-shaped metal support. By the step of forming a web, the step of peeling the formed web from the metal support to form a film, the step of stretching and drying the film (web), and the step of winding the dried film (web) into a roll after cooling Done. The retardation film of this embodiment preferably contains cellulose ester in the range of 60 to 95% by mass in the solid content.

<Dissolution process>
In the dissolution step, the cellulose ester, and in some cases, the retardation increasing agent, sugar ester, polycondensation ester, and other compounds in the dissolution vessel are stirred in an organic solvent mainly composed of a good solvent for the cellulose ester. It is a step of forming a dope which is a main solution by mixing a retardation increasing agent, a sugar ester, a polycondensation ester, and other compound solutions with the cellulose ester solution.

  When the retardation film of the present embodiment is produced by the solution casting method, an organic solvent useful for forming the dope can be used without limitation as long as it dissolves a cellulose ester, a retardation increasing agent and other compounds at the same time. Can do.

  For example, methylene chloride as the chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2, 2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2- Examples thereof include methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane and the like. For example, methylene chloride, methyl acetate, ethyl acetate, and acetone can be preferably used as the main solvent, and methylene chloride or ethyl acetate is particularly preferable.

  In addition to the organic solvent, the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass. When the ratio of the alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. Further, when the proportion of alcohol is small, it also has a role of promoting dissolution of cellulose ester and other compounds in a non-chlorine organic solvent system. In the production of the retardation film of the present embodiment, a method of producing using a dope having an alcohol concentration in the range of 0.5 to 15.0% by mass is applied in order to improve the flatness of the obtained retardation film. can do.

  In particular, a dope composition in which cellulose ester and other compounds are dissolved in a total amount of 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. Preferably there is.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Methanol and ethanol are preferred because of the stability and boiling point of these dopes being relatively low and good drying properties.

  In FIG. 2, first, cellulose ester is dissolved in a solvent in the charging pot 101 to form a first stage dope. This dope is passed through a filter 103 using a pump 102, and relatively large aggregates are removed by the filter 103. The dope from which the aggregate has been removed by the filter 103 is sent to the stock kettle 104.

  Subsequently, the dope of the stock pot 104 is sent to the main dope melting pot 105, and a compound such as a retardation increasing agent and a sugar ester is added, and these are dissolved and dispersed to prepare the main dope.

  Cellulose ester, retardation increasing agent, sugar ester, polycondensation ester or other compounds are dissolved at normal pressure, at a temperature lower than the boiling point of the main solvent, at a pressure higher than the boiling point of the main solvent, 9-95544, JP-A-9-95557, JP-A-9-95538, the method of performing the cooling and dissolution method, JP-A-11-21379, the method of performing at a high pressure, etc. Although various dissolution methods can be used, a method of pressurizing at a pressure equal to or higher than the boiling point of the main solvent is particularly preferable.

  The concentration of the cellulose ester in the dope is preferably in the range of 10 to 40% by mass.

  Thereafter, the main dope is sent to the main filter 107 using the pump 106.

  For dope filtration, it is preferable to filter the dope with a filter medium having a collection particle diameter of 90%, for example, 10 to 100 times the average particle diameter of the fine particles, in the main filter 107 having a leaf disk filter.

  In the present embodiment, the filter medium used for filtration preferably has a small absolute filtration accuracy. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged. As a result, the filter medium must be frequently exchanged, and there is a problem that productivity is lowered.

  For this reason, in this embodiment, the filter medium used for the cellulose ester dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and in the range of 0.003 to 0.006 mm. The filter medium is more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, filter fibers made of plastic fibers such as polypropylene and Teflon (registered trademark) and metal filter media such as stainless steel fibers may cause the fibers to fall off. Less preferred.

In the present embodiment, the dope flow rate during filtration is 10 to 80 kg / (h · m ² ), preferably 20 to 60 kg / (h · m ² ). Here, if the flow rate of the dope at the time of filtration is 10 kg / (h · m ² ) or more, it becomes efficient productivity, and if the flow rate of the dope at the time of filtration is within 80 kg / (h · m ² ). It is preferable that the pressure applied to the filter medium is appropriate and the filter medium is not damaged.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  The main dope after being filtered by the main filter 107 is sent to the stock kettle 108. Subsequently, the main dope of the stock kettle 108 is passed through the filter 110 using the pump 109 and then sent to the mixer 112 via the junction pipe 111. On the other hand, the matting agent dispersion liquid, the ultraviolet absorbent additive liquid, and the like are passed from the stock kettle 113 to the filter 115 using the pump 114 and then sent to the mixer 112 via the junction pipe 111. The mixer 112 adds a matting agent dispersion, an ultraviolet absorber addition liquid, and the like to the main dope.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material. Recycled material is, for example, a product obtained by finely pulverizing a cellulose ester-based film, which is generated when a cellulose ester-based film is produced. Cellulose ester film raw material is used.

  Moreover, as a raw material of the resin used for dope preparation, what pelletized cellulose ester and another compound previously can be used preferably.

<Casting process>
In the casting process, the dope is sent to a casting die 117 (eg, a pressure die) through a pump 116 (eg, a pressurized metering gear pump), and an endless metal support 118 (eg, a stainless steel belt) is transferred infinitely from the casting die 117. A web as a casting film by casting at a casting position on a rotating metal drum or the like.

  The metal support in the casting process is preferably a mirror finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The cast width can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, and more preferably in the range of 2 to 2.8 m.

  In the present embodiment, the metal support 118 is made of, for example, a stainless steel endless belt. The surface of the metal support 118 is a mirror surface. The metal support 118 is wound around and supported by a pair of front and rear pulleys 119 and a plurality of intermediate rolls (not shown). One or both of the pair of front and rear pulleys 119 is provided with a drive device (not shown) for applying tension to the metal support 118, whereby the metal support 118 is used in a tensioned state. The

  The surface temperature of the metal support in the casting step is set in the range of −50 ° C. to a temperature at which the solvent boils and does not foam, more preferably in the range of −30 to 0 ° C. A higher temperature is preferable because the web can be dried at a higher speed. However, if the temperature is too high, the web may foam or the flatness may deteriorate. A preferable temperature of the metal support is appropriately determined at 0 to 100 ° C, and more preferably in the range of 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum 120 in a state containing a large amount of residual solvent.

  A method for controlling the temperature of the metal support 118 is not particularly limited, and there are a method of blowing warm air or cold air, and a method of bringing hot water into contact with the back side of the metal support 118. It is preferable to use hot water because heat transfer is performed efficiently, so that the time until the temperature of the metal support 118 becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the metal support 118 and the temperature of the drying air between casting and peeling.

  As the casting die 117, it is preferable to use a pressure die that can adjust the slit shape of the die portion and easily make the film thickness uniform. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. In order to increase the manufacturing speed, two or more casting dies 117 made of a pressure die may be provided on the metal support 118, and the dope amount may be divided and laminated.

<Solvent evaporation process>
The solvent evaporation step is a step of heating the web (a dope film formed by casting a dope on the metal support 118 for casting) on the metal support 118 to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back surface of the metal support 118 by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency and preferable. A method of combining them is also preferably used. The web on the metal support 118 after casting is preferably dried on the metal support 118 in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, the web is preferably peeled from the metal support 118 within 30 to 120 seconds.

<Peeling process>
The peeling step is a step of peeling the web 120 having the solvent evaporated on the metal support 118 at the peeling position. The web 120 peeled from the metal support 118 is sent to the next process as a film.

  The temperature at the peeling position on the metal support 118 is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C. A peeling roller 121 is used for peeling the web 120 from the metal support 118.

  The residual solvent amount at the time of peeling the web 120 on the metal support 118 is preferably peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support 118, and the like. When the web 120 is peeled off at a time when the amount of the residual solvent is larger, if the web 120 is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes due to peeling tension are likely to occur. The amount of residual solvent at the time of peeling is determined by the balance.

  The residual solvent amount of the web 120 is defined by the following formula (10).

  Formula (10) Residual solvent amount (%) = (mass before heat treatment of web−mass after heat treatment of web) / (mass after heat treatment of web) × 100

  Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the metal support 118 and the web 120 is usually in the range of 196 to 245 N / m. However, if wrinkles easily occur when peeling, the peeling tension should be 190 N / m or less. Is preferred.

  In the present embodiment, the temperature at the peeling position on the metal support 118 is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferable.

<Extension process>
The stretching process is a process of stretching the web 120 obtained by peeling from the metal support 118. In the retardation film of the present embodiment, the orientation of molecules in the film can be controlled by stretching the web 120, and the target retardation value Ro in the in-plane direction and the retardation value Rth in the thickness direction are set. Can be obtained.

  The web 120 as the retardation film of the present embodiment may be stretched in the casting direction (hereinafter sometimes referred to as “MD direction”) and / or in the width direction (hereinafter sometimes referred to as “TD direction”). preferable. The retardation film is preferably produced by stretching the web 120 in the width direction by at least the tenter stretching device 122.

  The stretching process may be performed in multiple stages. Moreover, when performing biaxial stretching, simultaneous biaxial stretching may be performed and you may implement in steps. In this case, “stepwise” means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction can be divided into multiple stages, and stretching in different directions can be added to any one of the stages. Is possible.

Thus, for example, the following stretching steps are possible:
-Stretch in the casting direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction

  Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The amount of residual solvent at the start of stretching is preferably in the range of 2 to 10% by mass.

  If the amount of the residual solvent is 2% by mass or more, the film thickness deviation is small and it is preferable from the viewpoint of flatness, and if it is within 10% by mass, the surface unevenness is reduced and the flatness is improved.

  The retardation film of the present embodiment has a film transition temperature in the MD direction and / or TD direction, preferably in the TD direction so that the film thickness after stretching is in a desired range, and when the glass transition temperature of the film is Tg (Tg + 15) It is preferable to stretch in a temperature range of ~ (Tg + 50) ° C. If the stretching is performed within the above temperature range, the retardation can be easily adjusted, and the stretching stress can be reduced, so that the haze is lowered. Moreover, the retardation film which suppressed generation | occurrence | production of a fracture | rupture and was excellent in flatness and the coloring property of the film itself is obtained. The stretching temperature is preferably in the range of (Tg + 20) to (Tg + 40) ° C.

  The glass transition temperature Tg referred to here is a midpoint glass transition temperature (Tmg) determined according to JIS K7121 (1987) using a commercially available differential scanning calorimeter and measuring at a heating rate of 20 ° C./min. It is. A specific method for measuring the glass transition temperature Tg of the retardation film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

  The retardation film of this embodiment preferably stretches the web 120 at least 1.1 times in the TD direction. The range of stretching is preferably 1.1 to 1.5 times the original width, more preferably 1.2 to 1.4 times. If it is in the said range, the movement of the molecule | numerator in a film will be large and not only a desired phase difference value will be obtained, but a film can be thinned and planarity can be improved.

  In order to stretch the web 120 in the MD direction, it is preferable to peel the web 120 at a peeling tension of 130 N / m or more, particularly preferably 150 to 170 N / m. Since the web 120 after peeling is in a high residual solvent state, the web 120 can be stretched in the MD direction by maintaining the same tension as the peeling tension. As the web 120 dries and the residual solvent amount decreases, the stretch ratio in the MD direction decreases.

  The draw ratio in the MD direction can be calculated from the rotation speed of the belt support and the tenter operation speed in the tenter stretching device 122.

  In order to stretch the web 120 in the TD direction, for example, as shown in Japanese Patent Application Laid-Open No. 62-46625, the entire drying process or a part of the process is performed with clips or pins in the width direction. A method of drying while holding (called a tenter method) is used. Of these, a tenter method using a clip and a pin tenter method using a pin are preferably used.

  When the web 120 is stretched in the TD direction, it is preferable to stretch the web 120 in the width direction of the film at a stretching speed of 250 to 500% / min from the viewpoint of improving the flatness of the film. A stretching speed of 250% / min or more is preferable from the viewpoint of productivity because the flatness is improved and the film can be processed at a high speed. A stretching speed of 500% / min or less is preferable because the film can be processed without breaking.

  A preferred stretching speed is in the range of 300 to 400% / min. The stretching speed is defined by the following formula (11).

Formula (11) Stretching speed (% / min) = [(d1 / d2) -1] × 100 (%) / t
(In the formula, d1 is the width dimension of the stretched web (retardation film) in the stretching direction, d2 is the width dimension of the stretched web (retardation film) in the stretching direction, and t is stretched. (Time required (min))

The retardation film of this embodiment contains a retardation increasing agent, and inevitably has retardation by stretching. The in-plane retardation value Ro and the thickness retardation value Rth are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics) at a temperature of 23 ° C. and a relative humidity of 55% RH. The refractive indexes n _x , n _y , and _nz obtained by performing the three-dimensional refractive index measurement at the measurement wavelength of 590 nm can be calculated.

  The retardation film of this embodiment is represented by the following formulas (12) and (13), the retardation value Ro in the in-plane direction of the retardation film is in the range of 45 to 60 nm, and the retardation in the thickness direction. The value Rth is preferably in the range of 110 to 140 nm from the viewpoint of improving visibility such as viewing angle and contrast when applied to a vertical alignment type liquid crystal display device. The retardation film can be adjusted within the range of the retardation value by stretching while adjusting the stretching ratio at least in the TD direction.

Equation _{(12) Ro = (n x} -n y) × d (nm)
Equation (13) Rth = {(n x + n y) / 2-n z} × d (nm)
(Wherein, n _x is .n _y representing the refractive index in the direction x in which the refractive index is maximized in the plane direction of the film represents the refractive index in the direction y perpendicular to the direction x in the plane direction of the film. _nz represents the refractive index in the thickness direction z of the film, and d represents the thickness (nm) of the film.)

<Drying process>
The drying process is a process of drying the web 120 stretched in the stretching process. A drying process can also be performed by dividing into a preliminary drying process and a main drying process. The web 120 may be dried while being transported by a large number of rollers arranged above and below, or may be dried while being transported while fixing both ends of the web with clips like a tenter dryer. .

  In the present embodiment, for example, a drying device 123 is used. In the drying device 123, the web 120 is meandered by a plurality of conveying rolls arranged in a staggered manner as viewed from the side, and the web 120 is dried therebetween. The means for drying the web 120 is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roller, a microwave, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the drying step of the web 120 is preferably (glass transition temperature −5) ° C. or lower of the film, and it is effective to perform heat treatment at a temperature of 100 ° C. or higher for 10 minutes or longer and 60 minutes or shorter. More preferably, drying is performed within a range of 100 to 200 ° C.

  In particular, in the present embodiment, the drying step is performed within a range of 110 to 160 ° C. in which the drying temperature is (glass transition temperature Tg−30) ° C. or lower.

<Winding process>
This is a step of winding the web 120 as a film after the amount of residual solvent in the web 120 becomes 2% by mass or less. By setting the residual solvent amount to 0.4% by mass or less, a film having good dimensional stability can be obtained.

  For winding the web 120 after stretching and drying, for example, a winding device 124 is used. A winding method generally used may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

[Physical properties of retardation film]
<Haze>
The retardation film of the present embodiment 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 a film for optical applications.

<Equilibrium moisture content>
In the retardation film of this embodiment, the equilibrium moisture content at a temperature of 25 ° C. and a relative humidity of 60% RH is preferably 4% or less, and more preferably 3% or less. By setting the equilibrium moisture content to 4% or less, it is preferable that it is easy to cope with changes in humidity and the optical characteristics and dimensions are more difficult to change.

<Film length, width, film thickness>
The retardation film of the present embodiment is preferably long, specifically, preferably has a length of about 100 to 10,000 m, and is wound into a roll. The width of the retardation film of the present embodiment is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

  The film thickness is preferably in the range of 10 to 36 μm from the viewpoint of thinning the display device and productivity. If the film thickness is 10 μm or more, a certain level of film strength and retardation can be expressed. When the film thickness is 36 μm or less, the film has a desired phase difference and can be applied to thin the polarizing plate and the display device. Preferably, it exists in the range of 20-36 micrometers.

  Hereinafter, although an example is given and explained concretely, the example concerning this embodiment is not limited to these. Table 1 shows various properties of retardation films produced as examples and comparative examples. In the description of Examples and Comparative Examples, “part” or “%” is used, but “part by mass” or “% by mass” is expressed unless otherwise specified.

  The retardation film of Example 1 was produced according to the following method.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

99 parts by mass of methylene chloride 5 parts by mass of fine particle dispersion 1

  A main dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate butyrate having an acetyl group substitution degree of 2.0 and a butyryl group substitution degree of 0.5 was charged into a pressure dissolution tank containing a solvent while stirring. This was heated and dissolved completely with stirring. This was designated as Azumi Filter Paper No. The main dope was prepared by filtration using 244.

<Composition of main dope>
Methylene chloride 365 parts by weight Ethanol 50 parts by weight Cellulose acetate butyrate 100 parts by weight Retardation increasing agent R1 5 parts by weight Sugar ester S2 8 parts by weight Polycondensation ester P5 7 parts by weight

  The dope was prepared by putting the above into a sealed main dissolution vessel and dissolving with stirring.

  The solvent was evaporated until the residual solvent amount of the web of the retardation film cast (cast) on the stainless steel belt support reached 75%, and then the web was peeled off from the stainless steel belt support with a peeling tension of 130 N / m. . The peeled retardation film (web) was stretched 30% in the width direction using a tenter while applying heat at 150 ° C. The residual solvent at the start of stretching was 15%.

  Next, drying of the stretched retardation film web was completed while the drying zone was conveyed by a plurality of conveying rolls. The drying temperature was 110 ° C., and the transport tension was 100 N / m. As described above, the retardation film of Example 1 was obtained.

  In Example 2 and below, retardation films of Example 32 and Comparative Examples 1 to 7 were produced in the same manner as in Example 1 above. That is, the acetyl group substitution degree and butyryl group substitution degree, retardation increasing agent, and additive of cellulose acetate butyrate were changed as shown in Table 1, and retardation films were respectively produced.

[Compounds used in Examples and Comparative Examples]
The retardation increasing agents and additives indicated by symbols in Table 1 are described below.

<Retardation raising agent used in Examples and Comparative Examples>
R1: Exemplary compound 1 of the retardation increasing agent

R2: Illustrative compound 6 of the retardation increasing agent

R3: Exemplary compound 176 of the retardation increasing agent

R4: Exemplary compound 383 of the retardation increasing agent

上記化学式中、Ｒは炭素数１〜２０の脂肪族アルコール基を表す。 R5: 9H-carbazole-9-ethanol

In the above chemical formula, R represents an aliphatic alcohol group having 1 to 20 carbon atoms.

上記化学式中、Ｒ″は炭素数１〜２０の脂肪族アルキル基を表す。 R6: n-hexylcarbazole

In the above chemical formula, R ″ represents an aliphatic alkyl group having 1 to 20 carbon atoms.

上記化学式中、Ｒはそれぞれヘテロ原子を含むか含まない炭素数６〜２０のアリール基を表す。Ｒ′はそれぞれ水素または炭素数１〜２０の脂肪族アルキル基を表す。 R7: 2,3-diphenylquinoxaline

In the above chemical formulas, R represents an aryl group having 6 to 20 carbon atoms, each containing or not containing a hetero atom. R ′ represents hydrogen or an aliphatic alkyl group having 1 to 20 carbon atoms.

上記化学式中、Ｒは置換若しくは非置換された炭素数１〜２０の脂肪族基または置換若しくは非置換された炭素数６〜２０の芳香族基を表す。 R8: 2-methylbenzoxazole

In the above chemical formula, R represents a substituted or unsubstituted aliphatic group having 1 to 20 carbon atoms or a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms.

R10: Japanese Patent No. 5156067 Paragraph [0179] Compound U

R11: JP 2012-82235 A Exemplified Compound E-104

上記化学式中、Ｎ８のシクロヘキサンは１，４位でトランスに置換されている。 R12: Japanese Patent No. 3896404 The retardation increasing agent of Example 1 (no nitrogen atom)

In the above chemical formula, cyclohexane of N8 is substituted with trans at positions 1 and 4.

<Additives used in Examples and Comparative Examples>
S2: sugar ester; BzSc (benzyl saccharose: a mixture in which the sugar residue described in paragraph [0127] is B-2 and the substituents are a1 to a4), average ester substitution degree = 7.2
P5: Polycondensation ester P5 shown in the above-mentioned polycondensation ester synthesis example

≪Evaluation≫
<Derivation of humidity expansion coefficient>
The humidity expansion coefficient of the retardation film can be derived by the following procedure.

  First, the retardation film was conditioned by storing for 12 hours in an environment of a temperature of 23 ° C. and a relative humidity of 5% RH. Thereafter, the retardation film is cut into a size of 10 mm × 5 mm under the same environment, that is, at a temperature of 23 ° C. and a relative humidity of 5% RH, and is 50 mN using a TMA tester (Rigaku Thermo plus II TMA8310). It was humidified to 90% RH while pulling with tension. The elongation of the retardation film at that time was measured to calculate the humidity expansion coefficient.

<Evaluation of unevenness>
Evaluation of the unevenness of the retardation film can be performed by the following procedure.

  The produced vertical alignment type liquid crystal display device was laid and placed on a stand or the like, and Bencot (manufactured by Asahi Kasei Fibers) was placed on a part of the polarizing plate for evaluation to contain water. Covered with 100 μm PET so that the bencott does not dry, input a black display signal from the personal computer to the vertical alignment type liquid crystal display device, and left it for 24 hours with the power supply of the vertical alignment type liquid crystal display device turned on (room temperature is 23 ° C.) Setting and display panel temperature is 38 ° C).

After 24 hours, the becot was removed, and L ^* , a ^* , b ^* were measured (CS2000 made by Konica Minolta) between the portion with and without the becot from the direction of θ = 45 ° and ψ = 60 °. ΔE ^* ab was determined, and unevenness was evaluated according to the following criteria.

A: 0 or more and 1.0 or less: Generation of unevenness is not recognized at all.
◯: More than 1.0 and 1.50 or less: Although slightly weak unevenness is observed, the quality has no practical problem.
Δ: More than 1.50 and 2.4 or less: The occurrence of unevenness is slightly observed, and the quality is not so favorable.
X: More than 2.4: Strong unevenness occurs, and the quality has a problem with moisture resistance.

  According to Table 1, regarding the unevenness, the retardation films of all the examples satisfied at least a quality having no practical problem. In particular, it was confirmed that the retardation films of Examples 9 and 16 were able to realize good performance with respect to unevenness. On the other hand, the retardation films of all the comparative examples had undesirable quality or problematic quality.

  Thus, according to the said embodiment, the addition amount of a nitrogen-containing heterocyclic compound can be increased, and the retardation film (optical film 13, shown in FIG. 1 which can suppress the retardation fluctuation | variation by moisture absorption). 15) It is possible to provide a polarizing plate 5 having the retardation film, a vertical alignment type liquid crystal display device 1, and a method for producing the retardation film.

  In particular, the humidity expansion coefficient of the retardation film can be said to be 0.1 to 1.0% from Table 1 (the upper limit is a value between 0.9% and 1.2%). In the range of 0.7 to 0.9%, it can be said that a better result is obtained in order to suppress the occurrence of unevenness.

  In addition, in said Example, although the molecular weight of a retardation raising agent is 190-470, if the molecular weight was in the range of 100-800, it was confirmed that the same effect as said Example is acquired.

  Moreover, in said Example, although the addition amount of sugar ester (S2) is 8 mass% with respect to a cellulose ester, if it exists in the range of 1-20 mass%, the effect similar to said Example will be obtained. It was confirmed that it was obtained.

  Moreover, in said Example, although the addition amount of polycondensation ester (P5) is 7 mass% with respect to a cellulose ester, if it exists in the range of 1-20 mass%, the effect similar to said Example will be demonstrated. It was confirmed that

  Moreover, in said Example, although the drying temperature in the drying process of the web (retardation film) after extending | stretching is 110-120 degreeC, the drying temperature is (glass transition temperature Tg-30) degrees C or less, If it was in the range of 110-160 degreeC, it was confirmed that the same effect as said Example is acquired.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a retardation film, a polarizing plate having a retardation film, a vertical alignment type liquid crystal display device, and a method for producing a retardation film.

DESCRIPTION OF SYMBOLS 1 Vertical alignment type liquid crystal display device 2 Liquid crystal display panel 3 Backlight 4 Liquid crystal cell 5 Polarizing plate 6 Polarizing plate 13 Optical film (retardation film)
15 Optical film (retardation film)

Claims (5)

A retardation film formed by a solution casting method,
Cellulose ester satisfying both the following formulas (1) and (2) regarding the degree of substitution;
A nitrogen-containing heterocyclic compound;
Including
A retardation film having a humidity expansion coefficient of 0.1 to 1.0% when the environmental humidity is changed from 5% RH to 90% RH.
Formula (1) 2.0 <= X + Y <= 2.9
Formula (2) 0.1 <= Y <= 0.8
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the butyryl group.)   The retardation film according to claim 1, comprising at least one of a sugar ester and a polycondensation ester.   A polarizing plate comprising the retardation film according to claim 1.   A vertical alignment type liquid crystal display device comprising the polarizing plate according to claim 3. A method for producing a retardation film, wherein the retardation film according to claim 1 or 2 is formed by a solution casting method.
Having a step of stretching and drying a web formed by casting a resin composition containing a cellulose ester on a metal support;
The said process is performed at the drying temperature of (glass transition temperature Tg-30) degree C or less, The manufacturing method of retardation film characterized by the above-mentioned.

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