TWI582151B - Phase difference film, polarizing plate and vertical alignment type liquid crystal display device - Google Patents

Description

Phase difference film, polarizing plate and vertical alignment type liquid crystal display device

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

In the vertical alignment type liquid crystal display device using the cellulose-based retardation film, color unevenness due to the change in color tone of the display panel due to hysteresis of the retardation film is a problem. As in the conventional techniques described in Patent Documents 1 and 2, a retardation film using cellulose acetate butyrate is also proposed, but the improvement in hysteresis fluctuation due to moisture absorption is insufficient, and color unevenness occurs.

Further, the conventional retardation film has insufficient phase difference exhibitability, and it is difficult to maintain a desired phase difference and to reduce the thickness of the liquid crystal display device in recent years. In order to thin the retardation film while maintaining the phase difference satisfying the display performance, it is known to use a hysteresis rising agent. The hysteresis rising agent of such a retardation film is described, for example, in Patent Document 3.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] International Publication No. 2014/104616

[Patent Document 2] International Publication No. 2014/142465

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2012-82235

However, when a hysteresis rising agent is added to a conventional retardation film, the wet heat durability of the retardation film is deteriorated.

In view of the above, it is an object of the present invention to provide a retardation film capable of suppressing hysteresis fluctuation due to moisture absorption while maintaining a moist heat durability by a film structure, a polarizing plate having the retardation film, and Vertical alignment type liquid crystal display device.

1. A retardation film comprising a cellulose ester and a hysteresis-increasing agent which satisfy the following formulas (1) and (2), and at a temperature of 23 ° C and a relative humidity of 55% RH. In the environment, at a measurement wavelength of 590 nm, the photoelastic coefficient is in the range of 7.0 × 10 ^-13 to 25.0 × 10 ^-13 cm ² /dyn, and the phase difference Ro in the in-plane direction is 10 to 150 nm, and the phase difference in the thickness direction is Rth is 30~400nm, film thickness is 20~45μm; formula (1) 1.8≦X+Y≦2.9

Formula (2) 0.03 ≦ Y ≦ 0.8 (wherein, X represents the degree of substitution of the acetamidine group, and Y represents the degree of substitution of the butyl sulfhydryl group).

2. The retardation film according to the above 1, wherein the hysteresis-increasing agent is a nitrogen-containing heterocyclic compound and is a compound having a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring.

3. The retardation film according to the above 2, wherein the nitrogen-containing heterocyclic compound is a compound having a structure represented by the following formula (3). (wherein A represents a pyrazole ring, and Ar ₁ and Ar ₂ each represent an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and may have a substituent; and R ₁ represents a hydrogen atom, an alkyl group, a decyl group, a sulfonyl group, or an alkane. An oxycarbonyl group or an aryloxycarbonyl group; q represents an integer of 1 or 2, and n and m represent an integer of 1 to 3).

A polarizing plate comprising the retardation film according to any one of the above 1 to 3.

A vertical alignment type liquid crystal display device comprising the polarizing plate of the above 4.

According to the configuration of the present invention, it is possible to provide a retardation film which can maintain hygrothermal durability with a film structure and suppress hysteresis fluctuation due to moisture absorption, a polarizing plate having the retardation film, and a vertical alignment type liquid crystal display device.

1‧‧‧Vertical alignment type liquid crystal display device

2‧‧‧LCD panel

3‧‧‧ Backlight

4‧‧‧Liquid Crystal Cell

5‧‧‧Polar plate

6‧‧‧Polar plate

7, 8‧‧‧ adhesive layer

11, 14 ‧ ‧ polarized photons

13‧‧‧Optical film (phase difference film)

12, 15, 16‧‧ Optical film

Fig. 1 is a cross-sectional view showing a schematic configuration of a vertical alignment type liquid crystal display device according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described based on the drawings. In the present specification, when the numerical range is expressed by A to B, it means that the numerical range includes the values of the lower limit A and the upper limit B. Further, the present invention is not limited to the following.

[Summary of retardation film]

In the present embodiment, in order to maintain the moist heat durability by the configuration of the film and to suppress the hysteresis fluctuation due to moisture absorption, the retardation film is configured as follows. In other words, the retardation film of the present embodiment contains a cellulose ester and a hysteresis-increasing agent, and has a photoelastic coefficient of 7.0 × at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH. 10 ^-13 ~ 25.0 × 10 ^-13 cm ^{2 /} dyn (=7.0×10 ^-12 ~25.0×10 ^-12 /Pa=7.0×10 ^-12 ~25.0×10 ^-12 m ² /N), in-plane The phase difference Ro of the direction is 10 to 150 nm, the phase difference Rth in the thickness direction is 30 to 400 nm, and the film thickness is 20 to 45 μm. Further, the cellulose ester, in terms of the degree of substitution, satisfies 1.8 ≦ X + Y ≦ 2.9, 0.03 ≦ Y ≦ 0.8 (X represents the degree of substitution of the ethane group, and Y represents the degree of substitution of the butyl group).

In the conventional retardation film, the reason why the hysteresis changes due to moisture absorption is presumed as follows. That is, since the thiol group carbon number of the cellulose ester is large, the distance between the resins becomes long, and voids are generated, and once the moisture enters therein, it is difficult to leave, or the water molecules are substituted with the thiol group present in the cellulose halide resin. The carbonyl group of the group causes the birefringence to change.

In the present embodiment, the degree of substitution X of the ethyl sulfonyl group and the degree of substitution Y of the butyl sulfonate group are used, and a cellulose ester (cellulose acetate butyrate) satisfying the above specific relationship is used, and in the cellulose ester a compound (hysteresis-increasing agent) which is considered to terminate the interaction of a carbonyl or hydrogen atom of cellulose with water, or a compound which is coordinated to a side chain, a carbonyl group or a hydrogen atom of a cellulose ester, so that water becomes difficult to enter. On the other hand, the hysteresis variation due to moisture absorption of the retardation film is suppressed. In addition, it is considered that the phase difference exhibiting property of the retardation film is improved even if it is a film, and the dimensional change or the phase difference fluctuation due to the wet heat change is suppressed. Improve the durability of wet heat.

Further, by setting the photoelastic coefficient of the retardation film to the above range, even if an external force is generated due to shrinkage or expansion due to moisture absorption by the polarizer of the polarizing plate, the retardation film is contracted, expanded, or extended. The shrinkage caused by the residual stress and the generation of birefringence are also small. recognize In order to prevent the hysteresis fluctuation due to moisture absorption of the retardation film, the hysteresis variation can be further suppressed.

Further, it is desirable that the retardation increasing agent of the retardation film is a nitrogen-containing heterocyclic compound and is a compound having a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring. Further, the nitrogen-containing heterocyclic compound is desirably a compound having a structure represented by the above formula (3). According to such a configuration, the hysteresis fluctuation due to moisture absorption can be more effectively suppressed, and the display quality can be improved.

Then, the retardation film having the above configuration was placed on a polarizing plate. Further, the polarizing plate is mounted on a vertical alignment type liquid crystal display device. According to such a configuration, in the polarizing plate and the vertical alignment type liquid crystal display device, the hysteresis fluctuation due to moisture absorption of the retardation film can be suppressed, so that the color tone change due to color unevenness of the display panel can be improved.

[Configuration of Vertical Alignment Type Liquid Crystal Display Device]

Fig. 1 is a cross-sectional view showing a schematic configuration of a vertical alignment type (VA type) liquid crystal display device of 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 used to illuminate the light source of the liquid crystal display panel 2.

The liquid crystal display panel 2 is configured by arranging polarizing plates 5 and 6 on the front and back sides of the liquid crystal cell 4, respectively. The liquid crystal cell 4 is formed by sandwiching a liquid crystal layer with a pair of transparent substrates (not shown). As the liquid crystal cell 4, a vertical alignment type liquid crystal cell using an array color filter on array (COA) method may be used, but the color filter may be disposed in relation to the liquid crystal layer. The liquid crystal cell of the transparent substrate on the side (surface side) is visually recognized. The polarizing plate 5 is attached to the adhesive layer 7 via the adhesive layer 7 One side of the visual recognition side (surface side) of the liquid crystal cell 4. The polarizing plate 6 is attached to one surface of the liquid crystal cell 4 on the side of the backlight 3 (back side) via the adhesive layer 8.

The polarizing plate 5 is provided with a polarizer 11 and optical films 12 and 13. The polarizer 11 will be polarized through a specific straight line. The optical film 12 is a protective film disposed on the visual recognition 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 is provided with a polarizer 14 and optical films 15 and 16. The polarizer 14 will be polarized through a specific line. The optical film 15 is disposed on the visual recognition side of the polarizer 14. The optical film 16 is disposed on the backlight 3 side of the polarizer 14. Further, the optical film 15 on the visual recognition side 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 arranged to be in a crossed state.

As the retardation film of the present embodiment, an optical film 13 which is, for example, a polarizing plate 5 can be used.

[phase difference film]

The retardation film of the present embodiment contains a cellulose ester and a hysteresis-increasing agent, and has a photoelastic coefficient of 7.0×10 ^-13 to 25.0 at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH. The range of ×10 ^-13 cm ² /dyn, the phase difference Ro in the in-plane direction is 10 to 150 nm, the phase difference Rth in the thickness direction is 30 to 400 nm, and the film thickness is 20 to 45 μm. The details of each of these elements are described in the examples to be described later.

[photoelastic coefficient]

Photoelasticity means a phenomenon in which an external force is applied to an isotropic substance, and when an internal stress is induced, optical anisotropy is exhibited to exhibit birefringence. When the stress acting on the substance (force per unit area) is σ and the birefringence is Δn, the stress σ and the birefringence Δn are theoretically proportional, and can be expressed by Δn=Cσ, which is photoelastic coefficient. In other words, when the stress σ acting on the substance is the horizontal axis and the birefringence Δn of the substance when the stress is applied is the vertical axis, the relationship between the two is theoretically a straight line, and the slope of the straight line is the photoelastic coefficient C. The photoelastic coefficient can be adjusted by adjusting the kind of the resin and the additive constituting the retardation film or the content thereof.

[cellulose ester]

The cellulose ester is composed of cellulose acetate butyrate. When the degree of substitution of the ethyl acetate group is X and the degree of substitution with the butyl group is Y, it is preferred that the cellulose acetate butyrate satisfies the following (1) and (2). Further, the method of measuring the degree of substitution can be measured in accordance with ASTM-D817-96.

Equation (1) 1.8≦X+Y≦2.9

Equation (2) 0.03≦Y≦0.8

The cellulose ester can be produced by a known method. The raw material cellulose of the cellulose ester may, for example, be cotton linters, wood pulp, kenaf, etc., but is not particularly limited thereto. Further, the cellulose esters obtained by these can be used in combination at any ratio.

[hysteresis riser]

The retardation-increasing agent of the present embodiment has a phase difference Rth (measurement wavelength: 590 nm) in the thickness direction of the retardation film containing 3 parts by mass of the compound, based on 100 parts by mass of the cellulose ester, as compared with A phase difference film added, a compound exhibiting a function of 1.1 times or more.

The hysteresis-increasing agent is not particularly limited, and for example, a disc-shaped compound having an aromatic ring (1, 3, 5- described in paragraphs [0143] to [0179] of the above-mentioned Japanese Patent Publication No. 2006-113239 can be used. A pyrimidine compound described in paragraphs [0106] to [0133] of JP-A-2012-113682, and a pyrimidine compound described in paragraphs [0118] to [0133] of JP-A-2012-214682. JP-A-2011-140637, the epoxy compound described in paragraphs [0022] to [0028], and the polyester compound described in paragraphs [0044] to [0058] of International Publication No. 2012/014571.

The properties required for the hysteresis-increasing agent are excellent in compatibility with cellulose acetate butyrate as a resin, excellent in phase difference exhibitability when thinning a film, and excellent in precipitation resistance under high humidity. The phase difference variation resistance accompanying the entry and exit of moisture is excellent. From such a viewpoint, it is preferred to use the following nitrogen-containing heterocyclic compound as a retardation increasing agent.

[nitrogen-containing heterocyclic compound]

The hysteresis-increasing agent of the present embodiment is preferably a nitrogen-containing heterocyclic compound having a structure represented by the following formula (4).

The nitrogen-containing heterocyclic compound is obtained by CH/π with cellulose ester Interacting to control the hydrogen bonding property of the cellulose ester, and having the function of both the phase difference increasing agent and the wavelength dispersion adjusting agent in one compound, and having excellent compatibility with the cellulose ester, During the manufacturing process, the generation of minute foreign matter or precipitates is small. For example, the CH/π interaction of a 1,3,5-triazine-based phase difference increasing agent or the like is weak, and the compatibility is slightly inferior, foreign matter is likely to be generated, and the elution property to the saponified liquid tends to be large.

The CH/π interaction is related to the compatibility of an additive such as a hydrogen bond supply site of a cellulose ester (for example, a hydrogen atom of a hydroxyl group) or a hydrogen bond accepting site (for example, a carbonyl oxygen atom of an ester group) with an additive. The bond interaction between the hydrogen bonding site of the main chain or the side chain of the resin and the π electron of the aromatic compound of the additive. The above compatibility is excellent by the CH/π interaction.

When the hydrogen bonding site of the resin (CH of the cellulose ester) and the π of the additive form a CH/π interaction, it is of course preferable that the π property of the additive is stronger. An example of the strength directly indicating the π property is an index of the value of NICS (Nucleus-Independent Chemical Shift).

The NICS value is an index used to quantify aromaticity by magnetic properties. If the ring is aromatic, the center of the ring is strongly shielded due to its ring current effect. If it is anti-aromatic, it will be reversed. Masking (J. Am. Chem. Soc. 1996, 118, 6317). By the magnitude of the NICS value, the intensity of the ring current, that is, the contribution of the π electron to the aromaticity of the ring can be judged. Specifically, the NICS value indicates the chemical shift (calculated value) of the imaginary lithium ion directly disposed at the inner center of the ring, and the larger the value is, the stronger the π property is.

There are several reports on the measured values of the NICS values. The measured values are reported, for example, in Canadian Journal of Chemistry., 2004, 82, 50-69 (Document A) or The Journal of Organic Chemistry., 2000, 67, 1333-1338 (Document B).

Specifically, the pyrrole ring (-14.87), the thiophene ring (-14.09) furan ring (-12.42), and the pyrazole ring are compared to an aromatic hydrocarbon such as a benzene ring (-7.98) or a naphthalene ring (-8.11). -13.82), or a 5-membered aromatic heterocyclic ring such as an imidazole ring (-13.28); a 6-membered aromatic hydrocarbon such as a triazole ring (-13.18), an oxadiazole ring (-12.44) or a thiazole ring (-12.82) Ring, the NICS value is large (in the brackets, the NICS value is indicated). It is predicted that the CH/π interaction can be enhanced by using a compound having such an aromatic 5-membered ring or an aromatic 6-membered ring. Among them, a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring is preferred, and is excellent in compatibility with a cellulose ester.

The nitrogen-containing heterocyclic compound of the present embodiment is preferably a nitrogen-containing heterocyclic compound having a pyrrole ring, a pyrazole ring, a triazole ring or an imidazole ring, and a nitrogen-containing heterocyclic ring having a structure represented by the following formula (4). Among the compounds, a nitrogen-containing heterocyclic compound having the above specific ring structure is preferred. When a polarizing plate is used in a liquid crystal display device by using a compound having a structure represented by the following formula (4), it is possible to suppress occurrence of hysteresis fluctuation due to humidity fluctuation of the environment, and to suppress a decrease in contrast or Uneven color is produced. Further, by appropriately adjusting the type and amount of the nitrogen-containing heterocyclic compound, a function as a hysteresis-increasing agent for exhibiting a smooth wavelength dispersion property is exhibited.

From the point of view of controlling the affinity with the casting zone, the molecule The amount is preferably in the range of 100 to 800, more preferably in the range of 250 to 450.

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

In the above formula (4), A ₁ , A ₂ and B each independently represent an alkyl group (methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl, 2- Ethylhexyl or the like, a cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), an aromatic hydrocarbon ring or an aromatic hetero ring. Among them, an aromatic hydrocarbon ring or an aromatic heterocyclic ring, particularly preferably an aromatic hydrocarbon ring of 5 or 6 members, or an aromatic hetero ring is preferable.

The structure of the aromatic hydrocarbon ring or the aromatic heterocyclic ring of 5 or 6 members is not limited, and examples thereof include a benzene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring, and 1,2. , 4-triazole ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxazole ring, thiophene ring, thiazole ring, isothiazole ring, thiadiazole ring, different Thiadiazole ring and the like.

The aromatic hydrocarbon ring or the aromatic heterocyclic ring of 5 or 6 members represented by A ₁ , A ₂ and B may have a substituent. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), and an alkyl group (methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl). , 2-ethylhexyl, etc.), cycloalkyl (cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl, etc.), alkenyl (vinyl, allyl, etc.), cycloalkenyl (2 -cyclopenten-1-yl, 2-cyclohexen-1-yl, etc.), alkynyl (ethynyl, propargyl, etc.), aromatic hydrocarbon ring (phenyl, p-tolyl, naphthyl, etc.) , an aromatic heterocyclic group (2-pyrrolyl, 2-furyl, 2-thienyl, pyrrolyl, imidazolyl, oxazolyl, thiazolyl, benzimidazolyl, benzoxazolyl, 2-benzene) And thiazolyl, pyrazolone, pyridyl, pyridone, 2-pyrimidinyl, triazinyl, pyrazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, Oxazolyl, isoxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiazolyl, isothiazolyl, 1,2,4-thiadiazolyl, 1 , 3,4-thiadiazolyl, etc.), cyano, hydroxy, nitro, carboxy, alkoxy (methoxy, ethoxy, isopropoxy, tert-butoxy, n-octyloxy , 2-methoxyethoxy, etc.), Aryloxy (phenoxy, 2-methylphenoxy, 4-tert-butylphenoxy, 3-nitrophenoxy, 2-tetradecylaminophenoxy, etc.), oxime a base (methyloxy, ethoxycarbonyl, trimethylacetoxy, stearyloxy, benzyloxy, p-methoxyphenylcarbonyloxy, etc.), an amine group (amine group, Methylamino, dimethylamino, anilino, N-methyl-anilino, diphenylamino, etc.), mercaptoamine (methylamino), ethylamino, trimethyl Ethyl mercaptoamine, lauryl amine, benzhydrylamine, etc., alkyl and arylsulfonylamino (methylsulfonylamino, butylsulfonylamino, phenylsulfonate Mercaptoamine, 2,3,5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino, etc., mercapto, alkylthio (methylthio, ethylthio, n -hexadecanethio group, etc.), arylthio group (phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group, etc.), aminesulfonyl group (N-ethylaminesulfonyl group, N -(3-dodecyloxypropyl)aminesulfonyl, N,N-dimethylaminesulfonyl, N-acetamimidoxime, N-benzylhydrazinesulfonyl, N -(N ' -phenylaminemethanyl)amine sulfonyl, etc.), sulfo, oxime Base (ethylidene, trimethylethylbenzylbenzyl, etc.), amine methyl sulfhydryl (amine methyl sulfhydryl, N-methylamine methyl sulfhydryl, N, N-dimethylamine methyl sulfhydryl, N Each group such as N-di-n-octylaminecarbamyl, N-(methylsulfonyl)aminomethane, and the like.

In the above formula (4), when 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, A retardation film excellent in the effect of changing the optical characteristics and excellent in durability can be obtained, which is preferable.

In the above formula (4), T ₁ and T ₂ each independently represent 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 it can obtain a resin composition which is particularly excellent in suppressing the hysteresis fluctuation of humidity fluctuation and excellent in durability, and is preferably a pyrazole ring. T ₁ and T ₂ represents the pyrazole ring, an imidazole ring, a 1,2,3-triazole ring or a 1,2,4-triazole ring, may also be tautomeric. The specific structure of the pyrrole ring, the pyrazole ring, the imidazole ring, the 1,2,3-triazole ring or the 1,2,4-triazole ring is as follows.

In the formula, * represents a bonding position with L ₁ , L ₂ , L ₃ or L ₄ in the formula (4). R ⁵ represents a hydrogen atom or a non-aromatic substituent. R ⁵ represents a group of non-aromatic substituents include the aforementioned general formula (4) in the A ₁ may have a substituent group of a non-aromatic substituent group of the same group. When R ⁵ represents 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 cannot form an interaction with cellulose acetate. Therefore, it is difficult to suppress variations in optical characteristics. R ^{5 is} preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a mercapto group having 1 to 5 carbon atoms in order to improve the effect of suppressing fluctuation in optical characteristics; particularly preferably a hydrogen atom.

In the above formula (4), T ₁ and T ₂ may have a substituent. The substituent may be the same as the substituent which A ₁ and A ₂ in the above formula (4) may have.

In the above formula (4), L ₁ , L ₂ , L ₃ and L ₄ each independently represent a single bond or a divalent linking group, and the aromatic group of 5 or less members is bonded through two or less atoms. Hydrocarbon ring or aromatic heterocyclic ring. The term "through two or less atoms" means the smallest number of atoms existing between the connected substituents among the atoms constituting the linking group. The divalent linking group having 2 or less linked atoms is not particularly limited, and is selected from an alkyl group, an alkenyl group, an alkynyl group, O, (C=O), NR, S, (O=S=). O) A divalent linking group of the group formed, or a linking group obtained by combining the two. R represents a hydrogen atom or a substituent. Examples of the substituent represented by R include an alkyl group (methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl, 2-ethylhexyl, etc.), a cycloalkyl group (ring) Acryl 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 a -thienyl group, a 2-pyrimidinyl group, a 2-benzothiazolyl group, a 2-pyridyl group, etc.), a cyano group, etc. The divalent linking group represented by L ₁ , L ₂ , L ₃ and L ₄ may have a substituent. The substituent is not particularly limited, and examples thereof include the same substituents as those of A ₁ and A ₂ in the above formula (4).

In the above formula (4), L ₁ , L ₂ , L ₃ and L ₄ enhance the interaction with the resin adsorbing water by increasing the planarity of the compound having the structure represented by the above formula (4). , suppressing variations in optical properties, so it is preferably a single bond or O, (C=O)-O, O-(C=O), (C=O)-NR or NR-(C=O); more preferably Is a single button.

In the above formula (4), n represents an integer of 0 to 5. When n represents an integer of 2 or more, a plurality of A ₂ , T ₂ , L ₃ and L ₄ in the above formula (4) may be the same or different. The larger n is, the more the interaction between the compound having the structure represented by the above formula (4) and the resin adsorbing water is enhanced, so that the effect of suppressing the fluctuation of optical characteristics is excellent, and the smaller the n, the better the compatibility with the resin adsorbing water. . Therefore, n is preferably an integer of 1 to 3, more preferably an integer of 1 or 2.

[Compound having a structure represented by the general formula (5)]

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

(wherein 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 in the above formula (4) ₁ , L ₂ , L ₃ and L _{4 have the} same meaning. A ₃ and T ₃ respectively represent the same groups as A ₁ and T ₁ in the above formula (4). L ₅ and L ₆ represent the above formula (4) In the case where L _{1 is the} same base, m represents an integer of 0 to 4).

The smaller the m, the better the compatibility with the cellulose acetate, so m is preferably an integer of 0 to 2, more preferably an integer of 0 or 1.

[Compound having a structure represented by the general formula (6)]

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

(Wherein, A _1, B, L ₁ and L ₂ represents the general formula (4) in the A _1, B, L ₁ and L _{2 are} the same group .k integer of 1 to 4 represented by the ₁ .T 1 , 2,4-triazole ring).

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

(wherein Z represents a structure of the following formula (8). q represents an integer of 2 or 3. At least one of the Z-substituted benzene rings is bonded to at least one Z-line in the ortho or meta position).

(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 to a benzene ring. T ₁ represents a 1,2,4-triazole ring).

The compound having the structure represented by the above formula (4), (5), (6) or (7) may also form a hydrate, a solvate or a salt. Further, in the present embodiment, the hydrate may contain an organic solvent, and the solvate may also contain water. That is, "hydrate" and "solvate" include a mixed solvate containing any of water and an organic solvent. The salt system contains an acid addition salt formed with an inorganic or organic acid. Examples of the inorganic acid include hydrogen halide acid (hydrochloric acid, hydrobromic acid, etc.), sulfuric acid, phosphoric acid, and the like, and are not limited thereto. Further, examples of the organic acid include acetic acid, trifluoroacetic acid, propionic acid, butyric acid, oxalic acid, citric acid, benzoic acid, alkanesulfonic acid (methanesulfonic acid, etc.), and arylsulfonic acid (benzenesulfonic acid, 4- Further, toluenesulfonic acid, 1,5-naphthalene disulfonic acid, etc., and the like are not limited thereto. Among these, a hydrochloride, an acetate, a propionate, and a butyrate are preferred.

Examples of the salt include an acidic moiety present in the parent compound, a metal ion (for example, an alkali metal salt such as sodium or potassium salt; an alkaline earth metal salt such as calcium or magnesium salt; an ammonium salt alkali metal ion, an alkaline earth metal ion, Or an aluminum ion or the like, or a salt formed by adjusting to an organic base (ethanolamine, diethanolamine, triethanolamine, morpholine, piperidine, etc.), Limited to this. Among these, a sodium salt or a potassium salt is preferred.

Examples of the solvent contained in the solvate include all common organic solvents. Specific examples thereof include alcohols (for example, methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol, t-butanol), esters (for example, ethyl acetate), and hydrocarbons (for example). Toluene, hexane, heptane), ether (for example, tetrahydrofuran), nitrile (for example, acetonitrile), ketone (acetone), and the like. A solvate of an alcohol such as methanol, ethanol, 2-propanol, 1-butanol, 1-methoxy-2-propanol or t-butanol is preferred. These solvents may be a reaction solvent used in the synthesis of the above-mentioned compound, a solvent which can be used for precipitation and purification of the synthesized crystal, or a mixture thereof.

Further, it may contain two or more kinds of solvents at the same time, and may be in the form of water and a solvent (for example, water and an alcohol (for example, methanol, ethanol, t-butanol, etc.)).

Further, a compound having a structure represented by the above formula (4), (5), (6) or (7) may be added in the form of no water, a solvent or a salt; or in the retardation film of the present embodiment. Forming a hydrate, solvate or salt.

The molecular weight of the compound having the structure represented by the above formula (4), (5), (6) or (7) is not particularly limited, but the smaller the compatibility with the resin is, the larger the viscosity is. The variation of the optical value variation is high, so it is preferably from 150 to 2,000, more preferably from 200 to 1,500, still more preferably from 300 to 1,000.

Further, the nitrogen-containing heterocyclic compound of the present embodiment is particularly preferably a compound having a structure represented by the following formula (3).

(In the formula, A represents a pyrazole ring, and Ar ₁ and Ar ₂ each represent an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and may have a substituent. R ₁ represents a hydrogen atom, an alkyl group, a decyl group, a sulfonyl group, or an alkane. An oxycarbonyl 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 the aromatic heterocyclic ring represented by Ar ₁ and Ar ₂ is preferably an aromatic hydrocarbon ring or an aromatic heterocyclic ring of 5 or 6 members as exemplified in the general formula (4). Further, examples of the substituent of Ar ₁ and Ar ₂ include the same substituents as those exemplified for the compound having the structure represented by the above formula (4).

Specific examples of R ₁ include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), and an alkyl group (methyl, ethyl, n-propyl, isopropyl, tert-butyl, n-octyl). Base, 2-ethylhexyl, etc.), mercapto (ethenyl, trimethylethylbenzylbenzyl, etc.), sulfonyl (eg, methylsulfonyl, ethylsulfonyl, etc.), alkoxy A carbonyl group (e.g., methoxycarbonyl group), an aryloxycarbonyl group (e.g., phenoxycarbonyl group, etc.), 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 an aromatic hydrocarbon ring or an aromatic hetero ring having 5 members or 6 members in the present embodiment are described in the international publication. Paragraphs [0140] to [0214] of the 2014/109350. Among them, a compound having a structure represented by the above formula (4), (5), (6), and (7) is preferable, and a compound having a structure represented by the formula (3) is more preferable. Further, the compound having the above-mentioned aromatic hydrocarbon ring or aromatic heterocyclic ring of 5 or 6 members which can be used in the present embodiment is not subject to the paragraph [0140] to [0214] of the above-mentioned International Publication No. 2014/109350. Any definition of the specific examples described. Further, as described above, the above specific examples may be tautomers, and may also form a hydrate, a solvate or a salt.

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

The compound having the structure represented by the above formula (4) can be synthesized by a known method. In the compound having the structure represented by the above formula (4), the compound having a 1,2,4-triazole ring may be any starting material, preferably a nitrile derivative or an imino ether derivative, and a hydrazine. A method of reacting an anthracene derivative. The solvent to be used in the reaction may be any solvent as long as it is a solvent which does not react with the raw material, and examples thereof include an ester system (e.g., ethyl acetate, methyl acetate, etc.), a guanamine type (dimethylformamide, dimethyl group). Ethylamine, etc., ether (ethylene glycol dimethyl ether, etc.), alcohol (eg methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, ethylene glycol, ethylene) An alcohol monomethyl ether or the like, an aromatic hydrocarbon system (for example, toluene, xylene, etc.), or water. The solvent to be used is preferably an alcohol solvent. Further, these solvents may also be used in combination.

The amount of the solvent to be used is not particularly limited, and is preferably in the range of 0.5 to 30 times, more preferably 1.0 to 25 times, and particularly preferably 3.0 to 20, based on the mass of the anthracene derivative to be used. Within the range of multiples.

When the nitrile derivative is reacted with the anthracene derivative, the catalyst may not be used, but in order to accelerate the reaction, a catalyst is preferably used. The catalyst to be used may be an acid or a base. The acid may, for example, be hydrochloric acid, sulfuric acid, nitric acid or acetic acid, and is preferably hydrochloric acid. The acid can be added by dilution in water, and can also be added by blowing a gas into the system. The base can be an inorganic base (potassium carbonate, sodium carbonate, potassium hydrogencarbonate, sodium hydrogencarbonate, potassium hydroxide, sodium hydroxide, etc.) and an organic base (sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, sodium butyrate, butyl Potassium acid, diisopropylethylamine, N,N ' -dimethylaminopyridine, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, imidazole, N- Any of methyl imidazole, pyridine, etc.). The inorganic base is preferably potassium carbonate, and the organic base is preferably sodium ethoxide, sodium ethoxide or sodium butyrate. The inorganic base may be added directly in the form of a powder or may be added in a state of being dispersed in a solvent. Further, the organic base may be added in a state of being dissolved in a solvent (for example, a 28% methanol solution of sodium methoxide or the like).

The amount of the catalyst to be used is not particularly limited as long as it is carried out by the reaction, and is preferably in the range of 1.0 to 5.0 times the molar amount, more preferably 1.05 to 3.0 times the molar amount of the triazole ring to be formed. Within the scope.

When the imidoether derivative is reacted with an anthracene derivative, it is not necessary to use a catalyst, and the target can be obtained by heating in a solvent.

The method of adding the raw materials, the solvent and the catalyst used in the reaction is not particularly limited, and a catalyst may be added at the end or a solvent may be added at the end. Further, it is also preferred to disperse or dissolve the nitrile derivative in a solvent, and add a catalyst to add an anthracene derivative.

The temperature of the solution in the reaction, as long as the reaction will proceed to the temperature The degree may be any temperature, preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 140 ° C. Further, the reaction can be carried out while removing the generated water.

When the reaction solution is treated by any means, when a base is used as a catalyst, it is preferred to add an acid to the reaction solution to neutralize it. The acid used for the neutralization may, for example, be hydrochloric acid, sulfuric acid, nitric acid or acetic acid, and particularly preferably acetic acid. The amount of the acid to be neutralized is not particularly limited as long as the pH of the reaction solution is in the range of 4 to 9, and is preferably 0.1 to 3 times mol, particularly preferably 0.2 to the base to be used. 1.5 times the range of Moule.

When the reaction solution is treated by extraction with a suitable organic solvent, it is preferably a method in which the organic solvent is washed with water after extraction and then concentrated. The organic solvent as used herein means a water-insoluble solvent such as ethyl acetate, toluene, dichloromethane or ether; or a mixed solvent of the aforementioned water-insoluble solvent and tetrahydrofuran or an alcohol solvent, preferably acetic acid B. ester.

When the compound having the structure represented by the above formula (4) is precipitated and crystallized, it is not particularly limited, and it is preferred to add water to the neutralized reaction solution to precipitate crystals, or to dissolve the above-mentioned pass. A method of neutralizing an aqueous solution of a compound represented by the formula (4) to precipitate crystals.

[Synthesis of Synthesis of Compound 1]

For example, the exemplified compound 1 can be synthesized by the following scheme.

77.3 g (75.0 mmol) of benzonitrile, 34.0 g (25.0 mmol) of benzamidine hydrazine, and 107.0 g (77.4 mmol) of potassium carbonate were added to 350 ml of n-butanol, and the mixture was stirred at 120 ° C for 24 hours under a nitrogen atmosphere. The reaction liquid was cooled to room temperature, and the precipitate was filtered, and the filtrate was concentrated under reduced pressure. 20 ml of isopropyl alcohol was added to the concentrate, and the precipitate was collected by filtration. The precipitate obtained by filtration was dissolved in 80 ml of methanol, 300 ml of pure water was added, and acetic acid was dropped until the pH of the solution became 7. The crystals which precipitated were collected by filtration, washed with pure water, and dried by air at 50 ° C to obtain 38.6 g of the compound. The yield was 70% based on benzamidine.

The ¹ H-NMR spectrum of the obtained exemplified compound 1 is shown below.

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

[Synthesis of Synthesis of 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 benzalkonium hydride, and 9.0 g (68.3 mmol) of potassium carbonate were added under a nitrogen atmosphere at 120 ° C. Stir for 24 hours. After cooling the reaction mixture, 40 ml of pure water was added thereto, and the mixture was stirred at room temperature for 3 hours, and the precipitated solid was filtered off and washed with purified water. Water and ethyl acetate were added to the obtained solid to conduct liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was evaporated evaporated. The obtained crude crystals were purified by silica gel chromatography (ethyl acetate / heptane) to afford 5.5 g. The yield was 77% based on 1,3-dicyanobenzene.

The ¹ H-NMR spectrum of the obtained exemplified compound 6 is shown below.

¹ H-NMR (400 MHz, solvent: heavy hydrogen DMSO, standard: tetramethyl decane) δ (ppm): 8.83 (1H, s), 8.16 to 8.11 (6H, m), 7.67 to 7.54 (7H, m)

[Synthesis of Compound 176]

Exemplary compound 176 can be synthesized by the following scheme.

80 g (0.67 mol) of acetophenone and 52 g (0.27 mol) of dimethyl isophthalate were added to 520 ml of dehydrated tetrahydrofuran, and 52.3 g of sodium decylamine was added dropwise a little while stirring under ice cooling with ice water. (1.34 mol). After stirring under ice cooling for 3 hours, it was stirred under water cooling for 12 hours. After adding concentrated sulfuric acid to the reaction liquid for neutralization, pure water and ethyl acetate were added to carry out liquid separation, and the organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was evaporated evaporated. Methanol was added to the obtained crude crystals for suspension washing to obtain 55.2 g of Intermediate A.

Into 300 ml of tetrahydrofuran and 200 ml of ethanol, 55 g (0.15 mol) of the intermediate A was added, and while stirring at room temperature, 18.6 g (0.37 mol) of hydrazine monohydrate was dropped a little at a time. After the completion of the dropwise addition, the mixture was heated under reflux for 12 hours. Adding pure water and ethyl acetate to the reaction solution for liquid separation, The organic layer was washed with pure water. The organic layer was dried over magnesium sulfate, and the solvent was evaporated evaporated. The obtained crude crystals were purified by silica gel chromatography (ethyl acetate /hexane) to afford 27 g of the compound 176.

The ¹ H-NMR spectrum of the obtained exemplified compound 176 is shown below. Further, in order to avoid complication of chemical shift due to the presence of tautomers, a few drops of trifluoroacetic acid were added to the measurement solvent for measurement.

¹ H-NMR (400 MHz, solvent: dihydrogen DMSO, standard: tetramethyl decane) δ (ppm): 8.34 (1H, s), 7.87 to 7.81 (6H, m), 7.55 to 7.51 (1H, m), 7.48~7.44(4H, m), 7.36~7.33(2H, m), 7.29(1H, s)

Other compounds can also be synthesized by the same method.

[How to use the compound having the structure represented by the general formulae (3) to (5)]

The compound having the structure represented by the above formulas (3) to (5) in the present embodiment can be contained in the retardation film by adjusting an appropriate amount, and the amount of addition is preferably 0.1 to 0.1 in the retardation film. 10% by mass, particularly preferably 1% to 5% by mass, more preferably 2% to 5% by mass. Although the amount of addition varies depending on the type of the cellulose acetate and the type of the compound, the retardation film according to the present embodiment can determine the optimum value by displaying the amount of the desired phase difference. If it is within this range, the variation of the hysteresis depending on the change in the environmental humidity can be reduced without impairing the mechanical strength of the retardation film of the present embodiment.

In addition, the method of adding the compound having the structure represented by the above formulas (3) to (5) may be added as a powder to the resin forming the retardation film, or may be added to the solvent after being dissolved in the solvent. In the resin of the phase difference film.

<Other hysteresis risers>

In the present embodiment, in addition to the above compounds, the compounds disclosed in the following publicly known documents may be used as a hysteresis increasing agent. For example, Japanese Patent No. 5, 156, 067, Japanese Patent No. 3,896, 404, Japanese Patent No. 4,074, 454, Japanese Patent No. 4,234, 823, Japanese Patent Laid-Open No. 2012-82235, and Korean Patent Publication No. 2011-0075492 A compound disclosed in Korean Laid-Open Patent Publication No. 2011-0037289, Korean Laid-Open Patent Publication No. 10-2011-0075473, Korean Laid-Open Patent Publication No. 2011-0075199, and Korean Laid-Open Patent Publication No. 2011-0071493 use.

[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 photostabilizer, an antistatic agent, and a release agent. The compound which is more effectively used preferably contains a plasticizer, in particular, a sugar ester ester described below or a polycondensation ester containing a repeating unit obtained by reacting a dicarboxylic acid with a diol, and a cellulose ester Excellent compatibility, control the moisture in and out under high humidity, reduce the variation of the phase difference, and control the penetration of the saponification solution into the film, and improve the soap It is preferable from the viewpoint of the suitability.

[plasticizer] <sugar ester>

The sugar ester used in the retardation film of the present embodiment preferably has at least one of one or more 12 or less pyranose rings or a furanose ring, and all or a part of the OH group of the structure is esterified. Sugar ester. The sugar ester of the present embodiment is also preferably added for the purpose of preventing hydrolysis.

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

The sugar ester which is particularly preferable in the embodiment is a sugar ester represented by the following formula (A).

General formula (A) (HO) _m -G-(OC(=O)-R ² ) _n

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

It is known that a sugar ester having a structure represented by the general formula (A) is difficult to be isolated as a single compound having a fixed number of hydroxyl groups (m) and -(OC(=O)-R ² ) (n). A mixture of several different components of m and n. Therefore, it is important that the performance of the mixture in which the number (m) of the hydroxyl groups and the number (n) of the -(OC(=O)-R ² ) groups are changed is the same as that of the phase difference film of the present embodiment. It is a sugar ester having an average degree of ester substitution of 5.0 to 7.5.

In the above formula (A), G represents a residue of a monosaccharide or a disaccharide. Specific examples of the monosaccharide include, for example, allose, altrose, glucose, mannose, gulose, idose, galactose, teraloose, ribose, arabinose, xylose, and sucrose.

Specific examples of the compound having a monosaccharide residue of the sugar ester represented by the general formula (A) are shown below, but the present embodiment is not limited to the compounds exemplified above.

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

Specific examples of the compound having a disaccharide residue of the sugar ester represented by the general formula (A) are shown below, but the present embodiment is not limited thereto. Illustrative compounds.

In the 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.

Further, in the general formula (A), m is a total of the number of hydroxyl groups directly bonded to a residue of a monosaccharide or a disaccharide, and n is a -(OC(=O) which is directly bonded to a residue of a monosaccharide or a disaccharide. The sum of the number of -R ² ) groups. Further, 3 ≦ m + n ≦ 8 is necessary, and 4 ≦ m + n ≦ 8 is preferable. Also, n≠0. Further, when n is 2 or more, the -(OC(=O)-R ² ) groups may be the same or may be different from each other.

The aliphatic group in the definition of R ² may be linear, branched or cyclic; the carbon number is preferably from 1 to 25, more preferably from 1 to 20, and particularly preferably from 2 to 15. Specific examples of the aliphatic group include, for example, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a cyclopropyl group, an n-butyl group, an iso-butyl group, a tert-butyl group, a pentyl group, and an iso- Butyl, tert-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-fluorenyl, tert-octyl, dodecyl, hexadecan Each of an alkyl group, an octadecyl group, a diindenyl group 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 is preferably a carbon number of 6 to 24, more preferably 6 to 12. Specific examples of the aromatic hydrocarbon group include, for example, each of benzene, naphthalene, anthracene, biphenyl, and terphenyl. The aromatic hydrocarbon group is particularly preferably a benzene ring, a naphthalene ring or a biphenyl ring. 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 furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, anthracene, carbazole, anthracene, thiazoline, thiadiazole, and oxadiazole. Oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, pyridazine, natrile, quinoxaline, quinazoline, octyl, acridine, acridine, phenanthroline, phenazine, tetrazole, benzene Each of the rings of imidazole, benzoxazole, benzothiazole, benzotriazole, tetrazaindene, and the like. The aromatic heterocyclic group is particularly preferably a pyridine ring, a triazine ring or a quinoline ring.

Next, a preferred example of the sugar ester represented by the formula (A) is shown below, but the present embodiment is not limited to the compounds exemplified herein.

The sugar ester may have two or more different substituents in one molecule, and may contain an aromatic substituent and an aliphatic substituent in one molecule, and may contain two or more aromatics in one molecule. The substituent may contain two or more different aliphatic substituents in one molecule.

Further, it is also preferred to mix two or more kinds of sugar esters. It is also preferred to contain both a sugar ester containing an aromatic substituent and a sugar ester containing an aliphatic substituent.

<Synthesis Example: Synthesis Example of Sugar Ester Represented by General Formula (A)>

An example of the synthesis of the sugar ester which can be suitably used in the present embodiment is shown below.

In a four-head flask equipped with a stirring device, a reflux condenser, a thermometer, and a nitrogen introduction tube, 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, and 379.7 g (4.8 mol) of pyridine were respectively fed. The mixture was heated from a nitrogen gas introduction tube while stirring, and the temperature was raised, and the esterification reaction was carried out at 70 ° C for 5 hours. Then, the pressure in the flask was reduced to 4 × 10 ² Pa or less, and the excess pyridine was distilled off at 60 ° C, and the pressure in the flask was reduced to 1.3 × 10 Pa or less, and the temperature was raised to 120 ° C to distill off the benzoic anhydride and the resulting benzoic acid. the most part of. Then, 300 g of toluene 1 L and 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C for 30 minutes, and then allowed to stand, and the toluene layer was separated. Finally, 100 g of water was added to the toluene layer, and after washing at room temperature for 30 minutes, the toluene layer was separated, and under reduced pressure (4 × 10 ² Pa or less), toluene was distilled off at 60 ° C to obtain a compound A-1, A- 2. A mixture of A-3, A-4 and A-5. After the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 7 mass%, A-2 was 58 mass%, A-3 was 23 mass%, A-4 was 9% by mass, and A-5 was 3. The mass%, the average ester substitution degree of the sugar ester was 6.57. Further, a part of the obtained mixture was purified by cerium oxide gel column chromatography to obtain A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively.

The amount of the sugar ester added is preferably from 0.1 to 20% by mass, more preferably from 1 to 15% by mass, based on the cellulose ester.

<polycondensed ester>

The polycondensation ester used in the retardation film of the present embodiment is preferably a polycondensation ester having a structure represented by the following formula (9).

In the retardation film of the present embodiment, the polycondensation ester is preferably contained in the range of 1 to 30% by mass, more preferably 5 to 20% by mass.

General formula (9) B ₃ -(G ₂ -A) _n -G ₂ -B ₄

In the above formula (9), B ₃ and B ₄ each independently represent an aliphatic or aromatic monocarboxylic acid residue or a hydroxyl group. G ₂ represents an alkanediol residue having 2 to 12 carbon atoms, an aryl diol 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 polycondensation ester of the present embodiment contains a polycondensation ester of a repeating unit obtained by reacting a dicarboxylic acid with a diol, A represents a carboxylic acid residue in the polycondensed ester, and G ₂ represents an alcohol residue.

The dicarboxylic acid constituting the polycondensation 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 used alone or in combination of two or more. It is especially preferable to mix aromatic and aliphatic.

The diol constituting the polycondensation 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.

In particular, it is preferable to contain a repeating unit obtained by reacting a dicarboxylic acid containing at least an aromatic dicarboxylic acid with a diol having 1 to 8 carbon atoms, more preferably containing an aromatic dicarboxylic acid and an aliphatic dimer. A repeating unit obtained by reacting a dicarboxylic acid of a carboxylic acid with a diol having 1 to 8 carbon atoms.

The ends of the molecules of the polycondensation ester may or may not be sealed.

Specific examples of the alkylene dicarboxylic acid constituting A of the general formula (9) a group comprising 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1,4-butanedicarboxylic acid (adipic acid), 1, A divalent group derived from 5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) or the like. Specific examples of the alkylene dicarboxylic acid constituting A include maleic acid, fumaric acid, and the like. Specific examples of the aryldicarboxylic acid constituting A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,5- Naphthalene dicarboxylic acid and the like.

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

G ₂ in the formula (9) represents a divalent group derived from an alkanediol having 2 to 12 carbon atoms, a divalent group derived from an aryl diol having 6 to 12 carbon atoms or a carbon atom. A divalent group derived from a number of 4 to 12 oxyalkylene glycols.

Examples of the divalent group derived from an alkanediol having 2 to 12 carbon atoms in G ₂ include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 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-dihydroxymethylpentane), 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-nonanediol, and 1, A divalent group derived from 12-octadecanediol or the like.

Examples of the divalent group derived from an aryl diol having 6 to 12 carbon atoms in G ₂ include 1,2-dihydroxybenzene (catechol) and 1,3-dihydroxybenzene (between Divalent group derived from benzenediol), 1,4-dihydroxybenzene (hydroquinone) or the like. Examples of the divalent group derived from the oxyalkylene glycol having 4 to 12 carbon atoms in G include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. Derived 2 valence base.

G ₂ may be one type or two or more types. Among them, the G ₂ group is preferably a divalent group derived from an alkanediol having 2 to 12 carbon atoms, more preferably 2 to 5, most preferably 2 to 4.

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

The monocarboxylic acid containing an aromatic ring in the monovalent group derived from the monocarboxylic acid containing an aromatic ring is a carboxylic acid having an aromatic ring in the molecule, and includes not only an aromatic ring and a carboxyl group but also an aromatic ring. Alkyl groups and the like are bonded to a carboxyl group. Examples of the monovalent group derived from a monocarboxylic acid containing an aromatic ring include benzoic acid, p-tert-butylbenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, dimethyl benzoic acid, and B. A monovalent group derived from chiral acid, n-propyl benzoic acid, aminobenzoic acid, ethoxylated benzoic acid, phenylacetic acid, 3-phenylpropionic acid or the like. Among them, benzoic acid and p-toluic acid are preferred.

Examples of the monovalent group derived from an aliphatic monocarboxylic acid include a monovalent value derived from acetic acid, propionic acid, butyric acid, caprylic acid, caproic acid, capric acid, dodecanoic acid, stearic acid, oleic acid or the like. base. Among them, a monovalent group derived from an alkyl monocarboxylic acid having an alkyl moiety having 1 to 3 carbon atoms is preferred and more preferred. It is an ethyl group (a monovalent group derived from acetic acid).

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

Specific examples of the polycondensation ester having the structure represented by the general formula (9) are shown below, but are not limited thereto.

Hereinafter, specific synthesis examples of the polycondensation 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 fed into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a rapid cooling tube, and stirred while stirring in a nitrogen stream, and gradually heated to 230. °C. 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-propanediol, 103 g of phthalic anhydride, 244 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed with a thermometer, a stirrer, and a rapid cooling tube. The 2 L four-necked flask was stirred while stirring in a nitrogen stream, and gradually heated to 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the completion of the reaction, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C to obtain the following polycondensed ester P2. The acid value was 0.10 and the number average molecular weight was 450.

(polycondensation ester P3)

330 g of 1,4-butanediol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed with a thermometer, a stirrer, and a buffer. A 2 L four-necked flask of a cooling tube was stirred while stirring in a nitrogen stream, and gradually heated to 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the 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.

(polycondensation ester P4)

251 g of 1,2-propanediol, 354 g of terephthalic acid, 610 g of benzoic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a rapid cooling tube. While stirring in a nitrogen stream, the temperature was gradually raised to 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the completion of the reaction, unreacted 1,2-propanediol 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-propanediol, 354 g of terephthalic acid, 680 g of p-toluic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed into a 2L four-piece equipped with a thermometer, a stirrer, and a rapid cooling tube. The flask was stirred while stirring in a nitrogen stream, and gradually heated to 230 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the reaction is over, due to 200 ° C Unreacted 1,2-propanediol was distilled off under reduced pressure to give the following polycondensation ester P5. The acid value was 0.30 and the number average molecular weight was 400.

(polycondensation ester P6)

180 g of 1,2-propanediol, 292 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a rapid cooling tube. While stirring, the temperature was slowly raised to 200 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the completion of the reaction, unreacted 1,2-propanediol 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.

(polycondensation ester P7)

180 g of 1,2-propanediol, 244 g of phthalic anhydride, 103 g of adipic acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst were fed into a 2L four equipped with a thermometer, a stirrer, and a rapid cooling tube. The flask was stirred while stirring in a nitrogen stream, and gradually heated to 200 °C. The dehydration condensation reaction was carried out while observing the degree of polymerization. After the reaction is over, due to 200 ° C Unreacted 1,2-propanediol was distilled off under reduced pressure to obtain a polycondensed ester P7. The acid value was 0.10 and the number average molecular weight was 320.

(polycondensation 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 fed into a 2 L four-piece equipped with a thermometer, a stirrer, and a rapid cooling tube. The flask was stirred while stirring in a nitrogen stream, and gradually heated to 200 °C. 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.

(polycondensation ester P9)

The reaction conditions were changed in the same manner as in the above-mentioned polycondensation ester P2 to obtain a polycondensation ester P9 having an acid value of 0.10 and a number average molecular weight of 315.

<Other plasticizers>

Moreover, examples of other plasticizers include a polyol ester, a polyvalent carboxylate (including a phthalate), a glycolate compound, a fatty acid ester, a phosphate, and the like. These may be used alone or in combination of two or more.

The polyol ester-based aliphatic polyol and the monocarboxylic acid ester (alcohol ester) are preferably 2 to 20-membered aliphatic polyol esters. The polyol ester preferably has an aromatic ring or a cycloalkyl ring in the molecule.

Preferred examples of aliphatic polyols include ethylene glycol, diethyl ether Glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4 -butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, pentaerythritol, trishydroxyl Methyl ethane, xylitol, and the like. Among them, 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 or an aromatic monocarboxylic acid. In order to improve the moisture permeability of the film and to make volatilization difficult, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferred. The monocarboxylic acid may be used alone or in combination of two or more. Further, all of the OH groups contained in the aliphatic polyol may be esterified, or a part thereof may remain as an OH group.

The aliphatic monocarboxylic acid is preferably a fatty acid having a linear or side chain of 1 to 32 carbon atoms. The carbon number of the aliphatic monocarboxylic acid is preferably from 1 to 20, more preferably from 1 to 10. Examples of the aliphatic monocarboxylic acid include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanoic acid, undecanoic acid, lauric acid, and ten. Triacid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, ceric acid, twenty-seven acid, brown coal Saturated fatty acids such as montanoic acid, beeswax, and lacquer wax; unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linoleic acid, and arachidonic acid. Among them, in order to improve compatibility with cellulose acetate, acetic acid or a mixture of acetic acid and other monocarboxylic acids is preferred.

Examples of the alicyclic monocarboxylic acid include a cyclopentanecarboxylic acid, a ring Hexanecarboxylic acid, cyclooctanecarboxylic acid, and the like.

Examples of the aromatic monocarboxylic acid include benzoic acid; those in which a benzene ring of benzoic acid is introduced with 1 to 3 alkyl groups or alkoxy groups (for example, methoxy or ethoxy group) (for example, toluic acid or the like); The above benzene ring aromatic monocarboxylic acid (e.g., biphenyl carboxylic acid, naphthalene carboxylic acid, tetrahydronaphthalene carboxylic acid, etc.) is preferably benzoic acid.

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

The polyvalent carboxylic acid ester is a compound of 2 or more, preferably 2 to 20, and an ester of an alcohol compound. The polyvalent carboxylic acid is preferably an aliphatic polycarboxylic acid of 2 to 20 members, or an aromatic polycarboxylic acid of 3 to 20 members, or an alicyclic polycarboxylic acid of 3 to 20 members.

Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as trimellitic acid, symmetrical trimellitic acid, and pyromellitic acid, or derivatives thereof; such as succinic acid, adipic acid, sebacic acid, and hydrazine; Aliphatic polycarboxylic acid of diacid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthalic acid; hydroxypolycarboxylic acid such as tartaric acid, propanic acid, malic acid, citric acid, etc., for suppressing from the film The volatilization is preferably a hydroxypolycarboxylic acid.

Examples of the alcohol compound include an aliphatic saturated alcohol compound having a linear or side chain, an aliphatic unsaturated alcohol compound having a linear or side chain, an alicyclic alcohol compound or an aromatic alcohol compound, and the like. The carbon number of the aliphatic saturated alcohol compound or the aliphatic unsaturated alcohol compound is preferably from 1 to 32, more preferably from 1 to 20, still more preferably from 1 to 10. Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like. Examples of aromatic alcohol compounds are Contains benzyl alcohol, cinnamyl alcohol, and the like.

The molecular weight of the polycarboxylic acid ester is not particularly limited, and is preferably in the range of 300 to 1,000, more preferably in the range of 350 to 750. The molecular weight of the polycarboxylic acid ester-based plasticizer is preferably as large as possible from the viewpoint of suppressing outflow, and is preferably as small as possible from the viewpoint of moisture permeability or compatibility with cellulose acetate.

Examples of the polycarboxylic acid esters include triethyl citrate, tributyl citrate, ethoxylated triethyl citrate (ATEC), butyl citrate (ATBC), and benzhydryl citrate. Butyl ester, ethoxylated triphenyl citrate, ethoxylated tribenzyl citrate, dibutyl tartrate, dibutyl butyl tartrate, tributyl trimellitate, tetrabutyl trimellitate Wait.

The polycarboxylic acid ester can also be a phthalate ester. Examples of phthalates include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate Ester, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate, and the like.

Examples of the glycolate compound include alkyl phthalic acid alkyl acrylates. Examples of the alkyl phthalic acid alkyl phthalate include methyl phthalic acid methyl glycol phthalate, ethyl phthalic acid ethyl glycol phthalate, and sodium glycolate Phthamethyl propyl propyl ester, butyl phthalic acid butyl phthalate, octyl phthalic acid octyl phthalate, methyl phthalic acid ethyl phthalate , ethyl phthalic acid methyl phthalate, ethyl phthalic acid glyceryl glycol, methyl phthalate Mercaptobutyl ester, ethyl phthalate, glycol butyl phthalate, butyl phthalate, glycolic acid Propyl phthalic acid butyl acrylate, butyl phthalic acid butyl phthalate, methyl phthalic acid glycolic acid, ethyl phthalic acid glycolic acid The octyl ester, octyl phthalic acid methyl glycol glycolate, octyl phthalic acid ethyl glycol glycolate or the like is preferably ethyl phthalic acid ethyl phthalate.

The ester system includes a fatty acid ester, a citrate ester or a phosphate ester.

Examples of the fatty acid esters include butyl oleate, methyl phthalate of ricinoleic acid, and dibutyl sebacate. Examples of the citrate include acetoxytrimethyl citrate, ethyl citrate triethyl acrylate, and butyl citrate tributyl acrylate. Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, and tributyl phosphate. Preferably, triphenyl phosphate is used.

Among them, polyester, a glycolate compound, and a phosphate ester are preferable, and a polyester is particularly preferable.

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

〔Antioxidants〕

Antioxidants are also known as anti-deterioration agents. 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. Case.

The antioxidant has, for example, a phosphoric acid such as a halogen or a phosphate-based plasticizer in a retardation film in a retardation film, and the phase difference film is decomposed slowly or prevented. Therefore, it is preferred that the retardation film contains an antioxidant.

As such an antioxidant, a hindered phenol-based compound is preferably used, and examples thereof include 2,6-di-t-butyl-p-cresol and pentaerythritol-indole [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-dimethylene bis[3-(3,5-di-t-butyl) 4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N ' -hexa Bis(3,5-di-t-butyl-4-hydroxy-hydrocinnamate), 1,3,5-trimethyl-2,4,6-paran (3,5-di-t- Butyl-4-hydroxybenzyl)benzene, cis-(3,5-di-t-butyl-4-hydroxybenzyl)-trimeric isocyanate, and the like.

Particularly, 2,6-di-t-butyl-p-cresol, pentaerythritol-indole [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] is preferred. , triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate]. Further, a lanthanide metal inactivating agent or a ginseng such as N,N ' -bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propenyl] hydrazine may be used in combination. A phosphorus-based processing stabilizer such as 2,4-di-t-butylphenyl phosphite.

The amount of these compounds added relative to the cellulose ester In terms of mass ratio, it is preferably in the range of 1 ppm to 1.0%, more preferably in the range of 10 to 1000 ppm.

[UV absorber]

The retardation film of the present embodiment may contain an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function.

The ultraviolet absorber is not particularly limited, and examples thereof include ultraviolet absorbers such as benzotriazole-based, 2-hydroxybenzophenone-based or phenyl salicylate. For example, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H a triazole such as benzotriazole or 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole; 2-hydroxy-4-methoxybenzophenone, hydroxy-4-octyloxy benzophenone, 2,2 '- dihydroxy-4-methoxy benzophenone, etc. benzophenones.

Further, among the ultraviolet absorbers, the ultraviolet absorber having a molecular weight of 400 or more is not easily sublimed, or the high boiling point is not easily volatilized, and the film is not easily scattered when dried at a high temperature. Therefore, it is possible to improve the weather resistance with a small amount of addition. It is preferred from the viewpoint.

The ultraviolet absorber having a molecular weight of 400 or more may, for example, be 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2-benzotriazole, 2,2-Asia. a benzotriazole system such as methyl bis[4-(1,1,3,3-tetrabutyl)-6-(2H-benzotriazol-2-yl)phenol]; double (2, 2, A hindered amine system such as 6,6-tetramethyl-4-piperidinyl sebacate or bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate Further, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonic acid bis(1,2,2,6,6-pentamethyl- 4-piperidine Ester), 1-[2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propenyloxy]ethyl]-4-[3-(3,5-di- a mixed system of a structure of a hindered phenol and a hindered amine in a molecule such as t-butyl-4-hydroxyphenyl)propanooxy]-2,2,6,6-tetramethylpiperidine, etc. These may be used alone or in combination of two or more. Among these, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2-benzotriazole or 2,2-methylenebis[4 -(1,1,3,3-tetrabutyl)-6-(2H-benzotriazol-2-yl)phenol is particularly preferred.

Commercially available products can also be used for such ultraviolet absorbers. For example, Tinuvin series of Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc., manufactured by BASF Japan Co., Ltd.; 2 ' -Methylene bis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (molecular weight 659; commercially available An example is LA31 by ADEKA Co., Ltd.).

These ultraviolet absorbers may be used alone or in combination of two or more.

The amount of the ultraviolet absorber to be used is not necessarily determined depending on the type of the ultraviolet absorber, the use conditions, etc., but is generally 0.05 to 10% by mass, preferably 0.1 to 5 by mass based on the cellulose acetate. The range of % is added.

The ultraviolet absorber may be added to an organic solvent such as methanol, ethanol, butanol or the like, or an organic solvent such as dichloromethane, methyl acetate, acetone or dioxolane, or a mixed solvent thereof. After the agent is added, it may be added to the dopant or directly added to the dopant composition.

In the case of an inorganic powder, if it is not dissolved in an organic solvent, it is added to an organic solvent and cellulose acetate, and is dispersed by a dissolver or a sand mixer.

[Microparticles (matting agent)]

The retardation film of the present embodiment may further contain fine particles (matting agent) as needed in order to improve the slidability of the surface.

The microparticles may be inorganic microparticles or organic microparticles. Examples of the inorganic fine particles include cerium oxide (cerium oxide), titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, calcium citrate hydrate, and citric acid. Aluminum, magnesium citrate and calcium phosphate. Among them, cerium oxide or zirconium oxide is preferable, and in order to reduce the haze of the obtained film, cerium oxide is more preferable.

Examples of the fine particles of cerium oxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (made by Japan Aerosil Co., Ltd.), Seahostar KE-P10, KE-P30 , KE-P50, KE-P100 (above Japanese catalyst (share) system). Among them, Aerosil R972V, NAX50, Seahostar KE-P30, etc., are particularly preferable because the turbidity of the obtained film can be kept low while reducing the friction coefficient.

The primary particle diameter of the microparticles is preferably in the range of 5 to 50 nm, more preferably in the range of 7 to 20 nm. When the primary particle diameter is larger, the effect of improving the slidability of the obtained film is large, but the transparency is liable to lower. Therefore, the microparticles can also be in the secondary aggregate of the particle diameter in the range of 0.05 to 0.3 μm. Form contains. The size of the primary particles of the microparticles or their secondary aggregates can be observed by a penetrating electron microscope at a magnification of 500,000 to 2 million times, or as a primary particle or a secondary aggregate. The average value is obtained.

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

[Method of Manufacturing Phase Difference Film]

The retardation film of the present embodiment can be produced, for example, by a solution casting method.

[solution casting method]

Hereinafter, an example in which the retardation film of the present embodiment is produced by a solution casting method will be described.

The retardation film of the present embodiment is produced by dissolving at least a cellulose acetate and a hysteresis-increasing agent in a solvent to prepare a dopant and filtering the mixture; and extending the prepared doping stream to a strip or a circle a step of forming a web on the cylindrical metal support; a step of peeling the formed thin strip from the metal support to form a film; and a step of stretching/drying the film and cooling the dried film to be wound The step of the drum is carried out. The retardation film of the present embodiment preferably contains a cellulose ester in a range of 60 to 95% by mass based on the solid content.

<Solution step>

The dissolving step is carried out by stirring the cellulose ester in a dissolving kettle mainly in an organic solvent which is a good solvent for the cellulose ester, and stirring the hysteresis rising agent, the sugar ester, the polycondensed ester, and other compounds of the present embodiment as the case may be. a step of simultaneously dissolving to form a dopant; or mixing a hysteresis rising agent, a sugar ester, a polycondensation ester, and other compound solutions in the cellulose ester solution to form a dopant of the main solution.

When the retardation film of the present embodiment is produced by a solution casting method, an organic solvent for forming a dopant is used, and any cellulose ester, hysteresis-increasing agent, and other compounds may be dissolved at the same time.

For example, examples of the chlorine-based organic solvent include dichloromethane, and examples of the non-chlorine organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, and 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-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, the main solvent is preferably dichloromethane, methyl acetate, ethyl acetate or acetone, and particularly preferably dichloromethane or ethyl acetate.

The dopant is preferably a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass, in addition to the above organic solvent. When the ratio of the alcohol in the dopant is increased, the thin strips are gelled, and the peeling by the metal support becomes easy. Moreover, when the ratio of the alcohol is small, the cellulose ester and other chemicals in the non-chlorinated organic solvent system are also promoted. The role of the dissolved compound. In the production of the retardation film of the present embodiment, a method of producing a dopant having an alcohol concentration of 0.5 to 15.0% by mass can be applied from the viewpoint of improving the planarity of the obtained retardation film.

In particular, it is preferred to dissolve the cellulose ester and other compounds in a total of 15 to 45 mass% in a solvent containing a linear or branched aliphatic alcohol having dichloromethane and a carbon number of 1 to 4. Dopant composition.

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. Among these, methanol and ethanol are preferred from the viewpoints of stability of the dopant, lower boiling point, and good drying property.

The dissolution of a cellulose ester, a hysteresis-increasing agent, a sugar ester, a polycondensation ester or other compound can be carried out by a method for carrying out atmospheric pressure, a method of performing at a boiling point or lower of a main solvent, or higher than a boiling point of a main solvent. The method of performing the cooling-dissolving method described in the Unexamined-Japanese-Patent No. 9-95. Various methods of dissolving such as a method of performing at a high pressure are particularly preferably carried out by pressurizing at a boiling point or higher of the main solvent.

The concentration of the cellulose ester in the dopant is preferably in the range of 10 to 40% by mass. After the dissolved or added compound is dissolved and dispersed, it is filtered with a filter medium, defoamed, and pumped to the next step by liquid feeding.

Regarding the filtration of the dopant, it is preferable to use a filter having a leaf disk filter to make the dopant 10 to 100 times the average particle diameter of the particles by, for example, 90% of the particle diameter. The filter material is filtered.

In the present embodiment, the filter medium used for filtration is preferably one having a small absolute filtration accuracy, but the absolute filtration accuracy is too small, and clogging of the filter material is likely to occur. Therefore, there is a problem that it is necessary to frequently exchange the filter materials to reduce the productivity.

Therefore, in the present embodiment, the filter medium used for the cellulose ester dopant preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and more preferably 0.003 to 0.006 mm. Filter material.

The material of the filter material is not particularly limited, and a normal filter medium can be used, and a filter material made of a plastic fiber such as polypropylene or Teflon (registered trademark) or a metal filter material such as stainless steel fiber can be used because of no fiber falling off. good.

In the present embodiment, the flow rate of the dopant during filtration is preferably 10 to 80 kg/(h.m ² ), preferably 20 to 60 kg/(h.m ² ). Here, when the flow rate of the dopant at the time of filtration is 10 kg/(h.m ² ) or more, efficient productivity is obtained, and if the flow rate of the dopant during filtration is 80 kg/(h.m ² ) or less, The pressure applied to the filter medium is appropriate, and the filter material is not damaged, which is preferable.

The filtration pressure is preferably 3,500 kPa or less, more preferably 3,000 kPa or less, still more preferably 2,500 kPa or less. Furthermore, the filtration pressure can be appropriately selected Select filter flow and filter area to control.

A matting agent dispersion or an ultraviolet absorber addition liquid or the like is added to the filtered dopant.

In most cases, the main dopant may contain about 10 to 50% by mass of a return material. The term "returning material" refers to, for example, pulverizing a cellulose ester-based film into a finely divided material, which is obtained by cutting the both end portions of the film which are produced when the cellulose ester-based film is produced, or exceeding the film by scratches or the like. A cellulose ester-based film original film.

Further, the resin raw material used for the preparation of the dopant is preferably obtained by agglomerating a cellulose ester and other compounds in advance.

<casting step>

The casting step is a method of feeding a dopant to a pressurizing mold through a liquid feeding pump (for example, a pressurized quantitative gear pump), and feeding the metal support body (for example, a stainless steel belt, a rotating metal cylinder, etc.) to the infinite end. The upper casting position, the step of extending the doping stream from the press die slit.

The metal support in the casting (flow casting) step, preferably the surface is mirror finished. The metal support is preferably a cylinder obtained by subjecting the surface to a final treatment by plating with a stainless steel strip or casting. The width of the casting 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.

The surface temperature of the metal support in the casting step is set to be -50 ° C to a temperature at which the solvent does not boil and is foamed, and more preferably set to a range of -30 to 0 ° C. The higher the temperature, the faster the drying speed of the thin strip can be Good, but when it is too high, there may be cases where the slats are foamed or the planarity is deteriorated. The preferred temperature of the metal support is suitably determined at 0 to 100 ° C, more preferably 5 to 30 ° C. Alternatively, it is preferable to gel the thin strip by cooling and peeling from the cylinder in a state in which a large amount of residual solvent is contained.

The method of controlling the temperature of the metal support is not particularly limited, and is a method of blowing warm air or cold air, or a method of bringing warm water into contact with the back side of the metal support. The use of warm water allows for efficient heat transfer, so that the time until the temperature of the metal support is constant is short and preferable. When the warm air is used, the temperature of the thin slats is lowered in consideration of the evaporation potential of the solvent, and it is also possible to prevent the foaming and use a wind having a temperature higher than the target temperature while using the warm air above the boiling point of the solvent. In particular, it is preferred to carry out drying efficiently by changing the temperature of the support and the temperature of the dry air from the time of casting to the peeling.

It is preferable to adjust the slit shape of the metal port portion of the mold, and it is easy to make the film having a uniform film thickness. The press mold has a coat hanger mold or a T mold, and the like can be suitably used. The surface of the metal support is mirrored. In order to increase the manufacturing speed, two or more pressurizing dies may be provided on the metal support, and the amount of the dopant may be divided to be laminated.

<Solvent evaporation step>

The solvent evaporation step is a step of heating a thin strip (a dopant film formed by stretching a doping stream on a support for casting) on a casting support to evaporate a solvent.

In order to evaporate the solvent, the side is blown from the side of the thin strip. The method, the method of transferring heat from the back surface of the metal support or the method of transferring heat from the surface and the back surface by radiant heat, is preferable in that the drying efficiency is good by the back liquid heat transfer method. Further, it is preferable to use a combination of these methods. Preferably, the thin strip on the cast metal support is dried on the metal support in an environment of 40 to 100 ° C. In order to maintain the environment at 40 to 100 ° C, it is preferred to bring the warm air at this temperature into contact with the upper surface of the thin strip or by means of infrared rays or the like.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferred to peel the thin strip from the metal support within 30 to 120 seconds.

<Peeling step>

The peeling step is a step of peeling off the thin strip of the solvent after the solvent is evaporated on the metal support at the peeling position. The stripped strip is sent to the next step as a film.

The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

Further, the amount of the residual solvent at the time of peeling off the thin strip on the metal support is preferably in the range of 50 to 120% by mass, depending on the strength of the drying condition, the length of the metal support, and the like. When the thin strip is too soft at the time of peeling off the thin strip, if the thin strip is too soft, the flatness at the time of peeling is damaged, and the tension or the longitudinal streak due to the peeling tension is likely to occur, so that the economic speed is high. The balance with the quality determines the amount of residual solvent at the time of peeling.

The residual solvent amount of the thin strip is determined by the following formula (10) Righteousness.

Formula (10) Residual solvent amount (%) = (mass before heat treatment of thin slats - quality after heat treatment of thin slats) / (mass after heat treatment of thin slats) × 100

In addition, the heat treatment at the time of measuring the residual solvent amount shows the heat processing performed at 115 degreeC for 1 hour.

The peeling tension when the metal support is peeled off from the film (thin strip) is usually in the range of 196 to 245 N/m. However, when wrinkles are likely to occur during peeling, it is preferable to peel at a tension of 190 N/m or less.

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

<drying step>

The drying step is a step of drying the thin strip from the metal support. The drying step can also be carried out by dividing into a preliminary drying step and a formal drying step. Drying of the slats allows the slats to be dried while being conveyed by a plurality of rollers arranged one above the other, and the both ends of the slats can be conveyed and dried while being clamped and fixed as in a tenter dryer.

The means for drying the thin strip is not particularly limited. Generally, it can be carried out by hot air, infrared rays, a heating roller, microwaves, or the like. However, from the viewpoint of simplicity, it is preferably carried out by hot air.

The drying temperature in the drying step of the thin strip is preferably The glass transition temperature of the film is -5 ° C or lower, and at a temperature of 100 ° C or higher, heat treatment for 10 minutes or longer and 60 minutes or shorter is effective. The drying temperature is in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C.

<Extension step>

In the retardation film of the present embodiment, the alignment of the molecules in the film can be controlled by the stretching treatment, and the phase difference value Ro in the in-plane direction and the phase difference value Rth in the thickness direction can be obtained.

The retardation film of the present embodiment is preferably extended in the casting direction (hereinafter referred to as "MD direction") and/or in the width direction (hereinafter referred to as "TD direction"). Further, the retardation film is preferably produced by extending at least in the width direction by the tenter stretching device.

The extension operation can also be divided into multiple stages for implementation. Further, in the case of biaxial stretching, simultaneous biaxial stretching may be performed or may be carried out in stages. In this case, for example, the extension of the extension direction may be sequentially performed, or the extension of the same direction may be divided into multiple stages, and extension of different directions may be added at any of the stages.

That is, for example, the following extension steps may also be used;

. Extending in the casting direction → extending in the width direction → extending in the casting direction → extending in the casting direction

. Extending in the width direction → extending in the width direction → extending in the casting direction → extending in the casting direction

Further, the simultaneous biaxial stretching also includes a case in which the other side is extended and the other side is relaxed to contract. The amount of residual solvent at the start of stretching is preferably in the range of 2 to 10% by mass.

When the amount of the residual solvent is 2% by mass or more, the film thickness variation is small, and it is preferably from the viewpoint of planarity. When the amount is 10% by mass or less, the unevenness of the surface is reduced, and the planarity is improved.

The retardation film of the present embodiment preferably has a film thickness after stretching in a desired range, and is preferably in the MD direction and/or the TD direction, preferably in the TD direction, when the glass transition temperature of the film is Tg. , extending in the temperature range of (Tg + 15) ~ (Tg + 50) °C. When extending in the above temperature range, the adjustment of the hysteresis is easy, and the elongation stress can be lowered, so that the haze is lowered. Further, it is possible to obtain a retardation film which is excellent in the planarity and the coloring property of the film itself. The stretching temperature is preferably in the range of (Tg + 20) to (Tg + 40) °C.

In addition, the glass transition temperature Tg referred to herein means a half point glass transition temperature (Tmg) obtained by using a commercially available differential scanning calorimeter at a temperature increase rate of 20 ° C /min, in accordance with JIS K7121 (1987). ). The method for measuring the glass transition temperature Tg of the specific retardation film is measured in accordance with JIS K7121 (1987) using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments.

In the retardation film of the present embodiment, it is preferable that the thin strip extends at least 1.1 times in at least the TD direction. The extent of the extension is preferably 1.1 to 1.5 times, more preferably 1.2 to 1.4 times, relative to the original width. If it is within the above range, the molecular movement in the film is large, and not only the desired phase can be obtained. The difference in position and thinning of the film can improve planarity.

In order to extend in the MD direction, it is preferable to peel off the peeling force at 130 N/m or more, and particularly preferably 150 to 170 N/m. Since the thin strip after peeling is in a state of a high residual solvent, the extension in the MD direction can be performed by maintaining the same tension as the peeling tension. As the slats are dried and the amount of residual solvent is reduced, the elongation in the MD direction is lowered.

Further, the stretching ratio in the MD direction can be calculated from the rotation speed of the belt support and the tenter operation speed.

In order to extend in the TD direction, for example, in the drying step or a part of the steps disclosed in Japanese Laid-Open Patent Publication No. 62-46625, both ends of the width of the thin strip are pinched or pinned in the width direction. A method of keeping the width while drying (called the tenter method). Among them, it is particularly preferable to use a tenter type using a clip and a pin tenter method using a pin.

In the extension of the TD direction, from the viewpoint of improving the planarity of the film, it is preferred to extend at an elongation speed of 250 to 500%/min in the film width direction.

When the stretching speed is 250%/min or more, the planarity is improved, and the film can be processed at a high speed. Therefore, it is preferable from the viewpoint of production suitability, and if it is within 500%/min, the film can be prevented from being broken. It is better to treat it below.

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

Formula (11) Extension speed (%/min) = [(d1/d2)-1] × 100 (%) / t (wherein d1 is the width dimension of the extending direction of the cellulose ester film after stretching, d2 It is the width dimension of the aforementioned extending direction of the cellulose ester film before stretching, and t is the time (min) required for stretching.

The retardation film of the present embodiment contains a hysteresis rising agent, and has a hysteresis by extension. The phase difference Ro in the in-plane direction and the phase difference Rth in the thickness direction can be measured using an automatic birefringence meter Axo Scan (Axo Scan Mueller Matrix Polarimeter: Axometrics) at a temperature of 23 ° C and a relative humidity of 55% RH. Next, at a measurement wavelength of 590 nm, it was calculated from the refractive indices n _x , n _y , and n _z obtained by measuring the three-dimensional refractive index.

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

Formula (12) Ro=(n _x -n _y )×d(nm)

Formula (13) Rth={(n _x +n _y )/2-n _z }×d(nm) (wherein n _x represents a refractive index in a direction x in which the refractive index becomes maximum in the in-plane direction of the film. n _y represents a refractive index in the in-plane direction of the film in a direction y orthogonal to the aforementioned direction x. n _z represents a refractive index in the thickness direction z of the film, and d represents a thickness (nm) of the film.

<Rolling processing>

After a specific heat treatment or cooling treatment, since a good winding condition is obtained, it is preferred to provide a cutting machine to cut the end portion before winding. Further, it is preferable to perform embossing at both end portions in the width direction.

The knurling process can be formed by pressing a heated embossing cylinder. Fine embossing is formed in the embossing cylinder, and by pressing it, the film can be formed with irregularities to increase the volume of the end portion.

The embossing height at both end portions in the width direction of the retardation film of the present embodiment is preferably 4 to 20 μm and the width is preferably 5 to 20 mm.

Further, in the present embodiment, in the step of producing the film, the above-described embossing is preferably performed after the completion of the drying and before the winding.

<winding step>

This is a step of winding into a film after the amount of the residual solvent in the thin strip is 2% by mass or less. When the amount of the residual solvent is 0.4% by mass or less, a film having good dimensional stability can be obtained.

The winding method may be a normal torque method, a constant tension method, a cone tension method, a program tension control method in which internal stress is constant, and the like, and may be used as appropriate.

[Physical properties of retardation film] <Haze>

The retardation film of the present embodiment preferably has a haze of less than 1%, more preferably less than 0.5%. By making the haze less than 1%, the transparency of the film becomes higher, and the film for optical use is more advantageous.

<Equilibrium water content>

In the retardation film of the present embodiment, the equilibrium moisture content at a temperature of 25 ° C and a relative humidity of 60% RH is preferably 4% or less, more preferably 3% or less. When the equilibrium moisture content is 4% or less, it is easy to change depending on the humidity change, the optical characteristics, or the size, and it is preferable.

<film length, width, film thickness>

The retardation film of the present embodiment is preferably elongated, and specifically preferably has a length of about 100 to 10,000 m, and is wound into a roll shape. Further, 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 of the film is preferably in the range of 10 to 36 μm from the viewpoint of thickness reduction and productivity of the display device. When the film thickness is 10 μm or more, a film strength or a phase difference of more than a certain value can be exhibited. When the film thickness is 36 μm or less, the desired phase difference is provided, and the polarizing plate and the display device can be made thinner. It is preferably in the range of 20 to 36 μm.

The examples are specifically described below, but the examples of the embodiments are not limited thereto. Table 1 shows the respective characteristics of the retardation film produced as the examples and the comparative examples. In the description of the examples and comparative examples, the expression "parts" or "%" is used, unless otherwise specified. Indicates "parts by mass" or "% by mass".

[Examples]

The retardation film of Example 1 was produced in the following manner.

<Microparticle Addition Solution 1>

The fine particle dispersion 1 was gradually added while thoroughly stirring in a dissolution tank to which methylene chloride was added. Further, the dispersion is carried out by an attritor to make the particle diameter of the secondary particles a specific size. The fine particle addition liquid 1 was prepared by filtering it with FINE MET NF manufactured by Nippon Seisaku Co., Ltd.

A main dopant of the following composition was prepared. First, dichloromethane and ethanol were added to the pressure dissolution tank. To the pressurization dissolution tank to which the solvent was added, cellulose acetate butyrate having a degree of substitution of 2.6 oxime and a degree of substitution of butanyl group of 0.28 was introduced while stirring. This was heated and completely dissolved while stirring. The main dopant was prepared by filtering it using the filter paper No. 244 made of a filter paper (strand).

<Composition of main dopants>

The above-mentioned main dissolution vessel was placed in a sealed state, and dissolved while stirring to prepare a dopant.

The solvent was evaporated until the residual solvent amount of the thin strip of the retardation film cast on the stainless steel belt support (flow molding) was 75%, and then the thin strip was peeled off from the stainless steel strip support at a peeling tension of 130 N/m. The phase difference film (thin strip) after peeling was applied while applying heat of 150 ° C while extending by 30% in the width direction using a tenter. The residual solvent at the beginning of the extension was 15%.

Next, the thin strips of the stretched retardation film are conveyed to the drying zone by a plurality of rolls while the drying is completed. The drying temperature was set to 130 ° C and the conveying tension was set to 100 N/m. From the above, a retardation film of Example 1 having a dried film thickness of 38 μm was obtained.

A retardation film of Example 2 to Example 24 and Comparative Example 1 to Comparative Example 8 was produced in the same manner as in Example 1 described above. That is, as shown in Table 1, the degree of substitution of the ethyl acetate group of the cellulose acetate butyrate, the degree of substitution of the butyl group, the retardation increasing agent, and the additive were changed, and a retardation film was produced.

[Compounds used in the examples and comparative examples]

The hysteresis-increasing agent and the additive represented by the symbols in Table 1 are as follows.

<hysteresis riser used in the examples and comparative examples> R1: exemplified compound 1 of the aforementioned retardation riser

R2: an exemplary compound 6 of the aforementioned retardation riser

R3: exemplified compound 176 of the aforementioned retardation riser

R4: exemplified compound 383 of the aforementioned retardation riser

R5: 9H-carbazole-9-ethanol

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

R6: n-hexylcarbazole

In the above chemical formula, R represents an aryl group having 6 to 20 carbon atoms, which may or may not contain a hetero atom. R ' represents hydrogen or an aliphatic alkyl group having 1 to 20 carbon atoms, respectively.

R7: 2,3-diphenylquinoxaline

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.

R8: 2-methylbenzoxazole

In the above chemical formula, R and R ' each represent an aliphatic alkyl group having 1 to 20 carbon atoms. The difference in molecular weight between R and R ' is 20 to 200.

R9: 2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole

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

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

R11: Japanese Laid-Open Patent Publication No. 2012-82235, exemplified by the compound E-104

R12: Japanese Patent No. 3896404, Example 1 Hysteresis riser (no nitrogen atom)

In the above chemical formula, the cyclohexane of N8 is substituted at the 1,4 position.

R13: Japanese Patent No. 4074654, Example 1 Agent (no nitrogen atom) R14: Japanese Patent No. 4,234,823, the retardation riser of Example 1 (no nitrogen atom)

<Additives used in Examples and Comparative Examples>

S2: sugar ester; BzSc (benzyl sucrose: the sugar residue described in paragraph [0126] is B-2, the substituent is a mixture of a1~a4), and the average ester substitution degree is 7.2.

P5: polycondensation ester P5 shown in the above polycondensation ester synthesis example

≪Evaluation≫ <Measurement of hysteresis value>

The hysteresis value of the retardation film was measured by the above formula (12) using an automatic birefringence meter Axo Scan (manufactured by Axometrics Co., Ltd.) at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH. The phase difference Ro of the in-plane direction defined and the phase difference Rth in the thickness direction defined by the above formula (13).

Specifically, the produced retardation film was subjected to a three-dimensional refractive index measurement at ten sites at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH. Then, the average values of the refractive indices n _x , n _y , and n _{z are} obtained, and the phase difference Ro in the in-plane direction and the phase difference Rth in the thickness direction are calculated in accordance with the above formulas (12) and (13).

As a result, as shown in Table 1, in the phase difference film of the examples and the comparative examples, the phase difference Ro in the in-plane direction was in the range of 25 to 53 nm, and the phase difference Rth in the thickness direction was in the range of 110 to 140 nm. Inside.

<Measurement of Photoelastic Coefficient>

The measurement of the photoelastic coefficient of the retardation film can be carried out in the following order.

First, the retardation film was stored in an environment of a temperature of 23 ° C and a relative humidity of 55% RH for 24 hours. Then, in a state of a temperature of 23 ° C and a relative humidity of 55% RH, a tensile load was applied in a direction in which the film was extended in the maximum direction (the direction in which the stretching ratio became the maximum), and it was measured by KOBURA31PR (manufactured by Oji Scientific Instruments Co., Ltd.). The phase difference Ro of the in-plane direction of the film at a wavelength of 590 nm.

Then, while the tensile load applied to the retardation film is gradually increased, the phase difference value Ro of the in-plane direction of the retardation film for each tensile load is measured. Thereafter, the phase difference Ro in the in-plane direction of each tensile load is divided by the film thickness d, and Δn (=nx-ny) is calculated. Next, the transverse load was a tensile load and the vertical axis was Δn (=nx-ny) to obtain a tensile load-Δn curve. The slope of the straight line when the obtained curve is approximated to a straight line is the photoelastic coefficient.

<Evaluation of color unevenness>

The evaluation of the color unevenness of the retardation film can be performed in the following order.

A vertical alignment type liquid crystal display device was placed on a table or the like, and Bemcot® (manufactured by Asahi Kasei Fiber Co., Ltd.) was placed on one of the evaluation polarizing plates to make it contain water. The Bemcot® is covered with 100 μm PET in a non-drying manner, and the black display signal is input from the personal computer to the vertical alignment type liquid crystal display device, and the power supply of the vertical alignment type liquid crystal display device is turned ON for 24 hours (the room temperature is set to 23 ° C). The display panel temperature is 38 ° C).

After 24 hours, remove Bemcot® and measure the parts of Bemcot® and the parts of Bemcot®-free L ^* , a ^* , b ^* (CS2000 by Konica Minolta) from θ=45° and ψ=60°. The color difference ΔE ^* ab was obtained, and the evaluation of color unevenness was performed in accordance with the following criteria.

◎: 0 or more and 1.0 or less: No color unevenness was observed at all.

○: more than 1.0 and 1.50 or less: The occurrence of extremely weak color unevenness was observed, but the quality was not problematic in practical use.

△: more than 1.50, 2.4 or less: a weak color unevenness was observed, but it was a level which did not cause a problem in practical use.

×: More than 2.4: A strong color unevenness is generated, which is a problematic quality of moisture resistance.

<Durability evaluation related to wet heat dimensional change>

The durability evaluation relating to the change in the wet heat size of the retardation film can be performed in the following order.

The sample of the retardation film was cut into a size of 120 mm × 120 mm, and a cross-shaped mark was cut out at a distance of about 100 mm in the casting direction by a sharp knife such as a razor. Then, the film sample was conditioned for 24 hours or more in an environment of a temperature of 23 ° C and a relative humidity of 55% RH, and the inter-imprint distance L1 in the casting direction before the treatment was measured with a microscope.

Next, the film sample was subjected to high-temperature and high-humidity treatment for 120 hours in an environment of a temperature of 60 ° C and a relative humidity of 90% RH using an electric thermostat.

Next, the film sample after the high-temperature and high-humidity treatment was again humidity-conditioned for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 55% RH, and the inter-imprint distance L2 in the casting direction after the treatment was measured by a microscope. The rate of change before and after the treatment was obtained from the following equation, and the dimensional change rate was calculated.

Dimensional change rate (60 ° C 90% RH120h) = (L2-L1) / L1 × 100 (%)

◎: ±0~0.4%

○: ±0.5~0.8%

△: ±0.9~1.2%

×: ±1.3% or more

<Durability evaluation related to wet heat phase difference variation>

The durability evaluation relating to the change in the wet heat phase difference of the retardation film can be performed in the following order.

The sample of the retardation film was conditioned for 24 hours or more in an environment of a temperature of 23 ° C and a relative humidity of 55% RH, and the phase difference R1 was measured.

Next, the film sample was subjected to high-temperature and high-humidity treatment for 120 hours in an environment of a temperature of 60 ° C and a relative humidity of 90% RH using an electric thermostat.

Next, the film sample after the high-temperature and high-humidity treatment was again humidity-conditioned for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 55% RH, and the phase difference R2 was measured. The rate of change before and after the treatment was obtained from the following equation, and the phase difference change rate was calculated.

Phase difference change rate (60 ° C 90% RH120h) = (R2-R1) / R1 × 100 (%)

◎: ±4nm

○: ±5~10nm

△: ±11~18nm

×: ±19 nm or more

According to Table 1, with respect to color unevenness, the retardation film of all of the examples satisfies at least a level which is practically not problematic. Further, regarding the durability related to the change in the wet heat size and the change in the wet heat phase difference, it was confirmed that the retardation films of all the examples were improved with respect to the retardation film of the comparative example. In particular, it was confirmed that the retardation films of Examples 1, 12, 13, 14, and 21 can achieve good performance in all evaluations of color unevenness, wet heat size variation, and wet heat phase difference variation.

As described above, according to the above-described embodiment, it is possible to provide a film having a film thickness of 38 μm, and to maintain the phase difference of the hysteresis fluctuation due to moisture absorption while maintaining the moist heat durability (wet heat dimensional variation and wet heat phase variation). A film (optical film 13 shown in FIG. 1), a polarizing plate 5 having the retardation film, and a vertical alignment type liquid crystal display device 1.

In particular, the photoelastic coefficient of the retardation film can be said to be 7.0 × 10 ^-13 to 25.0 × 10 ^-13 cm ² /dyn as shown in Table 1 (the upper limit is 24.0 × 10 ^-13 cm ² /dyn a value between 27.0 × 10 ^-13 cm ² /dyn), but a range of 12.0 × 10 ^-13 to 15.0 × 10 ^-13 cm ² /dyn, because at least one of color unevenness and wet heat durability Better results can be obtained, so it is better.

Further, in the above embodiment, the film thickness of the retardation film is 38 μm, the phase difference Ro in the in-plane direction is 25 to 53 nm, and the phase difference Rth in the thickness direction is 110 to 140 nm, but it is confirmed that the film thickness is 20 to 45 μm. The phase difference Ro in the in-plane direction is 10 to 150 nm, and the phase difference Rth in the thickness direction is 30 to 400 nm, and the same effects as those of the above embodiment can be obtained.

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

[Industrial Applicability]

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

Claims (3)

A retardation film comprising a cellulose ester and a hysteresis-increasing agent which satisfy the following formulas (1) and (2), and the hysteresis-increasing agent is a nitrogen-containing heterocyclic compound, and the nitrogen-containing compound The heterocyclic compound is a compound having a structure represented by the following formula (3), and the retardation film has a photoelastic coefficient of 7.0 at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH. The range of ×10 ^-13 ~25.0×10 ^-13 cm ² /dyn, the phase difference Ro in the in-plane direction is 10 to 150 nm, and the phase difference Rth in the thickness direction is 30 to 400 nm; (1) 1.8≦X+Y≦ 2.9 Formula (2) 0.03≦Y≦0.8 (wherein, X represents the degree of substitution of the ethyl group, and Y represents the degree of substitution of the butyl group); (wherein A represents a pyrazole ring, and Ar ₁ and Ar ₂ each independently represent a benzene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring, and a 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxazole ring, thiophene ring, thiazole ring, isothiazole ring, thiadiazole ring, or isothiadiazole ring These may also have a substituent selected from a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, a cyano group, Hydroxy, nitro, carboxyl, alkoxy, aryloxy, decyloxy, amine, mercaptoamine, alkylsulfonylamino, arylsulfonylamino, alkylarylsulfonyl a group of an amine group, a mercapto group, an alkylthio group, an arylthio group, an aminesulfonyl group, a sulfo group, a fluorenyl group, and an amine carbenyl group; R ₁ represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group; , isopropyl, tert-butyl, n-octyl, 2-ethylhexyl, ethenyl, trimethylethylbenzylbenzyl, methylsulfonyl, ethylsulfonyl, methoxy Carbonyl or phenoxycarbonyl; q represents an integer of 1 or 2, and n and m represent an integer of 1 to 3) . A polarizing plate comprising the phase difference film of claim 1. A vertical alignment type liquid crystal display device comprising the polarizing plate of claim 2.