JP4836107B2 - Method for producing optical compensation film - Google Patents

Description

The present invention relates to the production how optical compensation film, and more particularly excellent viewing angle compensation function and durability slow axis direction of the refractive index in the film plane is improved changed humidity over time such as heat It relates to the production how optical compensation film having an.

  Liquid crystal display devices are widely used as display devices for word processors, personal computers, and the like because they can be directly connected to an IC circuit with low voltage and low power consumption and can be particularly thin. The liquid crystal display device has a basic configuration in which, for example, polarizing plates are provided on both sides of a liquid crystal cell.

  In such a liquid crystal display device, from the viewpoint of contrast and the like, a liquid crystal display device using a twisted nematic (TN) with a twist angle of 90 degrees, and a liquid crystal using a super twisted nematic (STN) with a twist angle of 160 degrees or more. Display devices have been developed, but a liquid crystal of a type different from the TN or STN type has been proposed. That is, a TN or STN type liquid crystal cell is a type of liquid crystal in which the liquid crystal molecules are parallel to the alignment plate when the voltage is turned off and the liquid crystal molecules are aligned perpendicular to the alignment plate when the voltage is turned on. A type in which the liquid crystal molecules are perpendicular to the alignment plate and parallel to the alignment plate when the voltage is turned on, for example, a so-called vertical alignment type using negative liquid crystal with negative dielectric anisotropy has been developed. . Such a vertical alignment type liquid crystal display device is disclosed in, for example, Japanese Patent Laid-Open No. 2-176625. This vertical alignment (vertical alignment, VA, abbreviated as VA) type liquid crystal display device is a so-called liquid crystal display in which liquid crystal molecules are aligned perpendicular to the alignment plate when the voltage is off and parallel to the alignment plate when the voltage is on. Since it is a vertical alignment mode liquid crystal cell, it has the characteristics that black is firmly displayed as black, the contrast is high, and the viewing angle is relatively wide compared to TN or STN type.

  However, as the liquid crystal screen becomes larger like a large TV, there is a growing demand for further widening the viewing angle, and a retardation film has been used for widening the viewing angle. Accordingly, with the enlargement of the liquid crystal screen, the optical compensation film is also increasingly widened.

  For this purpose, the application of a polymer film has been studied conventionally. Usually, a TAC film has a constant retardation value (Rt) in the thickness direction but an extremely small retardation value (Ro) in the in-plane direction. For example, it is not necessarily suitable for the purpose of improving the viewing angle of the VA LCD described above.

  In order to overcome this point, a film excellent in retardation value uniformity that becomes a polymer film and a polarizing plate protective film having a slow axis in the width direction by stretching the cellulose ester film at the time of film formation. It has been known.

  However, in large retardation films, it is known that a shift of the slow axis in the film causes a significant decrease in contrast, and a technique that focuses on the shift of the slow axis is disclosed to ensure display performance. (For example, refer to Patent Documents 1 and 2).

  Usually, an existing retardation film is post-bonded to a polarizing plate as disclosed in Patent Document 1. Even if such a conventionally used retardation film is a film for a large area, it is possible to adjust the misalignment of the axis at the time of bonding with the polarizing plate to obtain a final polarizing plate with a retardation film (ellipse). The light leakage of the polarizing plate) can be reduced.

  However, unlike a method in which at least one of the polarizing plate side or the retardation plate side is chip-cut and bonded with an adhesive, the retardation film that also serves as a polarizing plate protective film is produced by Roll to Roll by direct saponification treatment with PVA. Since lamination is performed, there has been a problem that the shift of the slow axis of the raw film is directly connected to light leakage after being converted into a polarizing plate.

Patent Document 2 discloses a technique related to the shift of the slow axis in the configuration in which the roll to roll lamination is performed. However, this technology only refers to suppressing display unevenness in the panel by suppressing the distribution of the shift of the slow axis that is obviously correlated with the amount of light leakage. In addition, it is disclosed that a polymer film having a phase difference having a low thermal conductivity is preferably used, but there is no mention about improving the durability of the viewing angle compensation function over time.
JP-A-11-160536 Japanese Patent Laid-Open No. 2002-22943

It is an object of the present invention is excellent and provides a production how optical compensation film having a viewing angle compensation function, manufacture how optical compensation film that can improve the durability of the viewing angle compensation function over time Is to provide.

The above object of the present invention is achieved by the following configurations.
(1)
A cellulose ester having 2.3 ≦ X + Y ≦ 2.85 and 1.4 ≦ X ≦ 2.85 when the acetyl substitution degree is X and the substitution degree of propionyl group or butyryl group is Y, In forming a film having an in-plane retardation Ro of 20 to 70 nm and a thickness direction retardation Rt of 70 to 400 nm and a width of 1.3 m to 4 m represented by the following formula, The film is stretched in the range of 1.05 to 1.5 times in the direction, and the film residual solvent amount is 5 to 30% by mass, and the temperature is 40 to 150 ° C., and the tension is 30 to 300 N / m . and dried while conveying a roll, an optical compensation film characterized in that relative to the extending direction of the film line as (0 °), the angle of the slow axis and the reference line to within 0.7 degrees in the film the whole width Manufacturing method.

(I) Ro = (nx−ny) × d
(II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film) Is the thickness of.)
( 2 )
The number average molecular weight (Mn) of the cellulose ester is 80000-200000, the value of weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.4-3.0, and relative to 100 parts by mass of the cellulose ester Te process for producing an optically compensatory film as described in 1 you comprising 0.01 to 20 parts by weight of at least two compounds having an aromatic ring.

The present invention, superior to provide a manufacturing how optical compensation film having a viewing angle compensation function, to provide a manufacturing how optical compensation film that can improve the durability of the viewing angle compensation function over time I can do it.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  In the present case, the present inventors used a polymer film having a low thermal conductivity in the case where a retardation function was imparted to the polarizing plate protective film (that is, a form adhered to PVA directly stretched without using an adhesive). Even if there is a portion where the maximum tilt angle of the slow axis of the protective film having the retardation function exceeds ± 0.7 degrees, an elliptical polarizing plate converted into a polarizing plate after bonding with the polarizer, It has been found that by maintaining high temperature dry and high temperature and high humidity conditions, the slow axis angle of the part is substantially enlarged, and the amount of light leakage of the display device is enlarged and uneven. In addition, in the case of such a film to be rolled to roll as a polarizing plate protective film, it is necessary to maintain a uniform slow axis angle in accordance with the width of the polarizing plate. Despite being a very important factor, there was no disclosure of a uniform film satisfying the above conditions over a width of 1.3 m or more.

  As a result, by keeping the slow axis of the protective film having the retardation function (particularly cellulose ester film) strictly within ± 0.7 degrees in the full width direction as a raw fabric roll, high temperature dry conditions, high temperature high Even when subjected to a durability test under wet conditions, the display characteristics are not deteriorated due to the change of the slow axis angle, and an elliptically polarizing plate which is extremely resistant to environmental fluctuations is obtained.

  As mentioned above, the liquid crystal display device generally has viewing angle characteristics, and there is a problem that the contrast is lowered when observed from a position having an angle from the normal direction of the liquid crystal cell. In order to solve this problem, it is known that it is effective to dispose an optical compensation film (retardation film) having an appropriate retardation between the liquid crystal cell and the polarizer.

  In the present invention, the retardation Ro in the in-plane direction is in the range of 20 to 70 nm, and the retardation Rt in the thickness direction is in the range of 70 to 400 nm.

  In order to control the retardation of a film mainly composed of cellulose ester, as one method, the degree of substitution of the cellulose ester used and the type of substituent are important factors. In the present invention, when the acetyl substitution degree of the cellulose ester is X and the substitution degree of the propionyl group and / or butyryl group is Y, 2.3 ≦ X + Y ≦ 2.85 and 1.4 ≦ X ≦ 2.85 Further, by stretching the film, it was possible to obtain a retardation suitable as an optical compensation film.

Furthermore, in this invention, the number average molecular weight (Mn) of the cellulose ester used for a cellulose-ester film is 80000-200000, and the value of a weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.4-3.0. There, and by stretching the cellulose ester film containing 0.1 to 20 parts by weight of at least two compounds having an aromatic ring with respect to the cellulose ester le 1 00 parts by mass, a suitable retardation as an optical compensation film I was able to get it.

  Films with a slow axis angle of ± 0.7 degrees or less in the width direction in the entire width region as raw rolls having a width of 1.3 m or more should be controlled in the temperature and transport of the tenter part by in-line stretching under residual solvent. Realized.

  The optical compensation film according to the present invention is a cellulose ester film having a width of 1.3 m or more by appropriately combining the above conditions. An optical compensation film can be obtained, and the change in viewing angle characteristics with time due to the change in slow axis angle with time, which is the object of the present invention, can be improved. Here, the slow axis angle refers to an angle formed between the slow axis and the reference line with the stretching direction of the cellulose ester film as the reference line (0 degree). When a roll-shaped film is stretched in the width direction, the direction perpendicular to the transport direction is taken as the reference line.

  Hereinafter, the present invention will be described in detail.

[Film formation of cellulose ester film]
First, a method for forming a cellulose ester film according to the present invention will be described (a solution casting film forming method is shown as a representative example).

<Dissolution process>
In the dissolution vessel, the dope is formed by dissolving the cellulose ester in an organic solvent mainly composed of a good solvent for the cellulose ester while stirring. There are various dissolution methods for dissolution, such as performing at normal pressure at a temperature below the boiling point of the main solvent, performing pressurization at a temperature above the boiling point of the main solvent, cooling to below zero degrees, or performing at high pressure. Both are preferable dissolution methods, but a high-temperature dissolution method in which the solution is dissolved in a pressurized state above the boiling point of the main solvent is more preferably used. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next process with a pump.

  In the dope, additives having various functions such as a plasticizer, an antioxidant, an ultraviolet absorber, a matting agent, and a retardation increasing agent can be added. These additives may be added together with the cellulose ester and the solvent during the preparation of the dope, or may be added during or after the dope preparation. Further, a thermal stabilizer such as an alkaline earth metal salt, an antistatic agent, a flame retardant, a slip agent, and an oil agent may be added.

<Casting process>
An endless metal belt or a rotating metal drum (hereinafter simply referred to as a metal support) that feeds the dope through a pressurized metering gear pump to a pressure die and has a mirror-finished surface at the casting position. This is a step of casting a dope from a pressure die. The die casting apparatus is preferably a pressure die that can adjust the slit shape of the die part and easily make the film thickness of the web uniform. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked.

In the present invention, a wide cellulose ester film is used. In particular, the width is 1.3 to 4 m . Good Mashiku is 1.4~2m. If it exceeds 4 m, conveyance becomes difficult. Moreover, the thickness of a cellulose-ester film is 10-200 micrometers, Preferably it is 10-150 micrometers, More preferably, it is 40-100 micrometers, and both width and thickness are adjusted with the conditions of a casting process and the below-mentioned drying process.

<Solvent evaporation process>
In this step, the organic solvent is evaporated by heating the web on a metal support. In order to evaporate the organic solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. Preferably used.

<Peeling process>
This is a step of peeling the web from which the organic solvent has evaporated on the metal support from the metal support. The peeled web is sent to the next drying step. If the residual solvent amount (described later) of the web at the time of peeling is too large, peeling will be difficult, or conversely, if it is peeled off after sufficiently drying on the metal support, part of the web will be peeled off.

  As a method for increasing the film-forming speed, there is gel casting that can remove most of the residual solvent. For example, a poor solvent for the cellulose ester is added to the dope, and the dope is cast and then gelled, and the temperature of the metal support is lowered to gel. When gelled on a metal support, the film strength is high, and even if the amount of residual solvent is large, it can be peeled off. As a result, peeling can be accelerated and the film forming speed can be increased. When peeling at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be impaired, or slippage and vertical stripes due to peeling tension will tend to occur, and the amount of residual solvent in peeling will increase due to the balance between economic speed and quality. It is decided. In this invention, it is preferable to peel at 10-120 mass%.

  It is preferable to adjust the temperature at the peeling position on the metal support to 10 to 40 ° C, and more preferably to 15 to 30 ° C. Moreover, it is preferable that the residual solvent amount of the web in a peeling position shall be 30-120 mass%. In the present invention, the residual solvent amount can be expressed by the following formula.

  When the film is formed on the belt-like support, the increase in speed promotes the above-described belt vibration. Considering the amount of residual solvent and belt length at the time of peeling, the film forming speed is preferably 10 to 120 m / min, more preferably 15 to 60 m / min.

  In the present invention, the residual solvent amount relative to the entire width of the web may be referred to as an average residual solvent amount or a residual solvent amount at the center, and may also refer to a local residual solvent amount such as a residual solvent amount at both ends of the web. is there.

<Drying process>
This is a step of drying the web using a drying device that alternately conveys the web through guide rolls arranged in a staggered manner and / or a tenter drying device that clips and conveys both ends of the web with clips. As a drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. Too much drying tends to impair the flatness of the finished film. The drying temperature throughout is preferably 40 to 250 ° C, more preferably 70 to 180 ° C. The drying temperature, the amount of drying air, and the drying time differ depending on the organic solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.

  In the drying process after peeling from the metal support surface, the web tends to shrink in both directions due to evaporation of the solvent. Shrinkage increases as the temperature rapidly dries. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point of view, for example, as shown in Japanese Patent Application Laid-Open No. 62-46625, in the entire drying process or a part of the process, the web is clipped in the width direction and dried while maintaining the width at both ends of the web. (In-line tenter method) is preferable. At this time, the retardation can be controlled by controlling the stretch ratio of the web, the amount of residual solvent, and the temperature.

  In the present invention, for example, the film residual solvent amount is 5 to 30% by mass, the film stretching temperature is 60 to 140 ° C., and the draw ratio is 1.05 to 1.5 times, preferably 1.15 to 1.35. By stretching at least in the width direction with a tenter in the double range, a retardation suitable for viewing angle compensation could be provided. At this time, the width direction (td direction) of the film was the nx direction, the longitudinal direction (md direction) was the ny direction, and the thickness direction was the nz direction. For the retardation value, the average refractive index of the sample was obtained from an Abbe refractometer. Furthermore, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), a three-dimensional refractive index measurement was performed at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH. Refractive indexes nx, ny, and nz were obtained by calculation from the measured values of the phase difference and the average refractive index.

  The retardation value can be obtained by substituting the obtained value into the following formula.

(I) Ro = (nx−ny) × d
(II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film) Is the thickness of.)
The stretching operation may be performed in multiple stages, or biaxial stretching may be performed in the casting direction and the width direction. Also, when biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.

-Stretching in the casting direction-Stretching in the width direction-Stretching in the casting direction-Stretching in the casting direction-Stretching in the width direction-Stretching in the width direction-Stretching in the casting direction-Stretching in the casting direction Then, in order to obtain a suitable retardation, the film is preferably stretched in the width direction in a range of a draw ratio of 1.05 to 1.5 times.

  In the tenter process, the fact that the film atmosphere temperature distribution is small has a preferable range from the viewpoint of enhancing the uniformity of the film. The temperature distribution in the tenter process is preferably within ± 5 ° C, more preferably within ± 2 ° C, and most preferably within ± 1 ° C. By reducing the temperature distribution, it can be expected that the temperature distribution in the width of the film is also reduced.

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

  When the tenter process is completed, the film is in a state in which more strain remains in the td direction than in the md direction. Therefore, in the present invention, after the width stretching in the tenter is completed, the amount of residual solvent in the film is 5 to 30% by mass and the temperature is 40 to 150 ° C., and the tension is in the range of 30 to 300 N / m, more preferably 57 to The maximum tilt angle of the slow axis with respect to the stretching direction is ± 0.7 degrees over the entire width of the film by drying while relaxing the residual strain in the td direction while roll transporting at 284 N / m, particularly preferably 57 to 170 N / m. An optical compensation film that is within the range can be produced. At this time, relaxation in the td direction is an important condition. For example, by repeating the conveyance with 400 or more rolls in the range of the temperature and tension conditions, the slow axis characteristic condition that is a requirement of the present invention is satisfied. Can be achieved.

<Winding process>
This is a step of winding the web after drying as a film. When the amount of residual solvent at the end of drying is 2% by mass or less, preferably 1% by mass or less, and particularly preferably 0.4% by mass or less, a film having good dimensional stability can be obtained. The winding method may be a commonly used winder, and there are methods for controlling the tension such as the constant torque method, constant tension method, taper tension method, and program tension control method with constant internal stress. That's fine.

  The amount of residual solvent can be expressed by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point, and N is the mass when M is dried at 110 ° C. for 3 hours.

  The thickness of the cellulose ester film varies depending on the purpose of use, but from the viewpoint of thinning the liquid crystal display device, the finished film is preferably in the range of 10 to 200 μm, preferably 10 to 150 μm, and more preferably 40 to 100 μm. If it is too thin, for example, the required strength as a protective film for a polarizing plate may not be obtained. If it is too thick, the advantage of thinning the conventional cellulose ester film is lost. In adjusting the thickness, it is preferable to control the dope concentration, the pumping amount, the slit gap of the die base, the extrusion pressure of the die, the speed of the metal support and the like so as to obtain a desired thickness. Further, as a means for making the thickness uniform, it is preferable to use a film thickness detection means to feed back and adjust the programmed feedback information to each of the above devices.

  In the process from immediately after casting through the solution casting film forming method to drying, the atmosphere in the drying apparatus may be air, or may be performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. . However, it is a matter of course that the danger of the explosion limit of the evaporating solvent in the dry atmosphere must always be considered.

[Cellulose ester film and its composition]
The cellulose as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  The number average molecular weight (Mn) of the cellulose ester used in the present invention is 80000-200000. More preferred are 100,000 to 200,000, particularly preferably 150,000 to 200,000.

  The cellulose ester used in the present invention has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio, Mw / Mn of 1.4 to 3.0 as described above, but preferably 1.7. It is the range of -2.2. It is preferable to use a cellulose ester in this range in order to further obtain the effects of the present invention.

  The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high performance liquid chromatography. Using this, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (Mw / Mn) can be calculated.

The measurement conditions are as follows.
Solvent: Methylene chloride column: Shodex K806, K805, K803G (used by connecting 3 products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The cellulose ester used in the present invention is obtained by acylating a cellulose raw material. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), an organic acid such as acetic acid or an organic solvent such as methylene chloride is used, and a protic catalyst such as sulfuric acid is used as a catalyst. To react. When the acylating agent is an acid chloride (eg, CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by the method described in JP-A-10-45804.

  The cellulose ester used in the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, and is particularly preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, etc., JP-A-10-45804, Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in U.S. Pat. No. 8,231,761, U.S. Pat. No. 2,319,052 can be used. Alternatively, an ester of an aromatic carboxylic acid and cellulose and cellulose acylate described in JP-A Nos. 2002-179701, 2002-265639, and 2002-265638 are also preferably used. Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can be used as a mixture.

  In the cellulose ester, the acyl group reacts with the hydroxyl group of the cellulose molecule. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution.

  The cellulose ester used in the present invention has a total acyl group substitution degree of 2.3 to 2.85.

  Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, satisfying the following formula simultaneously when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y: It is a cellulose ester.

(III) 2.3 ≦ X + Y ≦ 2.85
(IV) 1.4 ≦ X ≦ 2.85
(However, X is a substitution degree of an acetyl group, Y is a substitution degree of a propionyl group and / or a butyryl group.)
Among them, cellulose acetate propionate (total acyl group substitution degree = X + Y) satisfying 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 is preferable. The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

  These acyl group substitution degrees can be measured according to the method prescribed in ASTM-D817-96.

  In order to control the retardation and slow axis characteristics of the cellulose ester film, the degree of substitution of the cellulose ester used and the type of substituent are important factors. In the present invention, when the cellulose ester satisfies the above formula, it is easy to obtain a suitable retardation as a viewing angle compensation polarizing plate.

By further comprising 0.01 to 20 parts by weight of aromatic ring to be described later at least two compounds having the cellulose ester le 1 00 parts by mass, a suitable retardation and the slow axis characteristics as a viewing angle compensation cellulose ester film It is easy to obtain a film having

[Additive for cellulose ester film (support)]
In the present invention, it is preferable to use a compound having at least two aromatic rings. Further, it is more preferable that the compound has at least two aromatic rings and at least two aromatic rings have a planar structure. In order to produce a cellulose ester film containing the compound, the compound and the cellulose ester film are contained in a dope together with an organic solvent, and formed by a solution casting film forming method.

  A compound having at least two aromatic rings according to the present invention and having at least two aromatic rings having a planar structure may have a structure in which two aromatic rings are close to the same plane. That is, it has at least 5 or more and up to 10 π electrons of π electrons of two aromatic rings, π electrons of aromatic heterocycles, or aromatic rings including a linking group connecting them. It is preferable.

  Moreover, it is preferable that the number of the aromatic rings which this compound has is 2-20, More preferably, it is 2-12, More preferably, it is 2-8. The aromatic ring includes an aromatic hydrocarbon ring and an aromatic heterocycle. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable.

  Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable.

  The bond relationship of at least two aromatic rings is (a) when a condensed ring is formed, (b) when directly linked by a single bond, (c) when linked via a linking group, and (d) having π electrons It can be classified into the case of bonding through a linking group (a spiro bond cannot be formed because of an aromatic ring). However, in the case of (b) or (c), it is necessary that the two aromatic rings have a planar structure.

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

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

  The linking group of (c) or (d) or the linking group having π electrons is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed. For example, -CO-O-, -CO-NH-, -alkylene-O-, -NH-CO-NH-, -NH-CO-O-, -O-CO-O-, -O-alkylene-O -, -CO-alkenylene-, -CO-alkenylene-NH-, -CO-alkenylene-O-, -alkylene-CO-O-alkylene-O-CO-alkylene-, -O-alkylene-CO-O-alkylene. -O-CO-alkylene-O-, -O-CO-alkylene-CO-O-, -NH-CO-alkenylene-, -O-CO-alkenylene-, etc. As the group directly linked to the aromatic heterocycle, —CO— or alkenylene is preferable.

  The aromatic ring and the linking group may have a substituent. However, the substituent must have a structure that does not cause steric hindrance of the two aromatic rings, that is, a planar structure. In steric hindrance, the type and position of substituents are problematic. As the type of substituent, a sterically bulky substituent (for example, a tertiary alkyl group) is likely to cause steric hindrance, and the position of the substituent is a position adjacent to the bond of the aromatic ring (the benzene ring). If the ortho position is substituted, steric hindrance is likely to occur and should be avoided.

  Examples of the substituent include halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl group, alkenyl group, alkynyl group, aliphatic acyl group , Aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic Substituted sulfamoyl groups, aliphatic substituted ureido groups and non-aromatic heterocyclic groups are included.

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

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

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

  The molecular weight of these compounds is preferably 300 to 800. The boiling point is preferably 260 ° C. or higher. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Electronics Industry Co., Ltd.). A specific example is shown below.

  Furthermore, the compound having at least two aromatic rings used in the present invention and having at least two aromatic rings having a planar structure has a triphenylene ring represented by the following general formula (1) in addition to the above. Compounds are also preferably used.

In general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, a halogen atom, nitro, sulfo, an aliphatic group, an aromatic group or a heterocyclic ring. Group, —O—R ₁₁ , —S—R ₁₂ , —CO—R ₁₃ , —O—CO—R ₁₄ , —CO—O—R ₁₅ , —O—CO—O—R ₁₆ , —NR ₁₇ R _{18, -CO-NR 19 R 20} , -NR 21 -CO-R 22, -O-CO-NR 23 R 24, -SiR 25 R 26 R 27, -O-SiR 28 R 29 R 30, -S- CO—R ₃₁ , —O—SO ₂ —R ₃₂ , —SO—R ₃₃ , —NR ₃₄ —CO—O—R ₃₅ , —SO ₂ —R ₃₆ or —NR ₃₇ —CO—NR ₃₈ R ₃₉ R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ , R ₁₉ , R ₂₀ , R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , _{R 27, R 28, R 29} , R 30, R 31, R 32, R 33, _{34, R 35, R 36,} R 37, R 38 and R ₃₉ each independently represent a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group; and, R ₁ and R _2, R ₃ R ₄ or R ₅ and R ₆ may combine with each other to form a ring.

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are —O—R ₁₁ , —S—R ₁₂ , —O—CO—R ₁₄ , —O—CO—O—R ₁₆ , — NR ₁₇ R ₁₈ , —NR ₂₁ —CO—R ₂₂ or —O—CO—NR ₂₃ R ₂₄ is preferred, —O—R ₁₁ , —S—R ₁₂ , —O—CO—R ₁₄ , — More preferably, it is O—CO—O—R ₁₆ or —O—CO—NR ₂₃ R ₂₄ , more preferably —O—R ₁₁ or —O—CO—R ₁₄ , and —O—CO—. and most preferably R _14.

_{R 11, R 12, R 13} , R 14, R 15, R 16, R 17, R 18, R 19, R 20, R 21, R 22, R 23, R 24, R 25, R 26, R 27 , R ₂₈ , R ₂₉ , R ₃₀ , R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , R ₃₅ , R ₃₆ , R ₃₇ , R ₃₈ and R ₃₉ are a hydrogen atom, an aliphatic group or an aromatic group. It is preferable. R ₁₄ of -O-CO-R ₁₄ is most preferably an aromatic group. In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are preferably the same group.

  In the present invention, the aliphatic group means an alkyl group, an alkenyl group, an alkynyl group, a substituted alkyl group, a substituted alkenyl group and a substituted alkynyl group. The alkyl group may be cyclic (cycloalkyl group). Moreover, the alkyl group may have a branch. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, and most preferably 1-10. Examples of alkyl groups include methyl, ethyl, i-propyl, butyl, i-butyl, s-butyl, t-butyl, t-pentyl, hexyl, octyl, t-octyl, dodecyl and tetracosyl. The alkenyl group may be cyclic (cycloalkenyl group). The alkenyl group may have a branch. The alkenyl group may have two or more double bonds.

  The alkenyl group has preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and most preferably 2 to 10 carbon atoms. Examples of the alkenyl group include vinyl, allyl and 3-heptenyl. The alkynyl group may be cyclic (cycloalkynyl group). Moreover, the alkynyl group may have a branch. The alkynyl group may have two or more triple bonds. The number of carbon atoms in the alkynyl group is preferably 2 to 30, more preferably 2 to 20, and most preferably 2 to 10. Examples of the alkynyl group include ethynyl, 2-propynyl, 1-pentynyl and 2,4-octadiynyl.

Examples of the substituent of the substituted alkyl group, the substituted alkenyl group and the substituted alkynyl group include a halogen atom, nitro, sulfo, an aromatic group, a heterocyclic group, —O—R ₄₁ , —S—R ₄₂ , —CO—R. ₄₃ , —O—CO—R ₄₄ , —CO—O—R ₄₅ , —O—CO—O—R ₄₆ , —NR ₄₇ R ₄₈ , —CO—NR ₄₉ R ₅₀ , —NR ₅₁ —CO—R _{52 , -O-CO-NR 53 R} 54, include -SiR ₅₅ R ₅₆ R ₅₇ R ₅₈ and _{-O-SiR 59 R 60 R 61} R 62. _{R 41, R 42, R 43} , R 44, R 45, R 46, R 47, R 48, R 49, R 50, R 51, R 52, R 53, R 54, R 55, R 56, R 57 , R ₅₈ , R ₅₉ , R ₆₀ , R ₆₁ and R ₆₂ are each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group.

  The alkyl part of the substituted alkyl group is the same as the above alkyl group. Examples of substituted alkyl groups include benzyl, phenethyl, 2-methoxyethyl, ethoxymethyl, 2- (2-methoxyethoxy) ethyl, 2-hydroxyethyl, hydroxymethyl, 2-carboxyethyl, carboxymethyl, ethoxycarbonylmethyl, 4-acryloyloxybutyl, trichloromethyl and perfluoropentyl are included. The alkenyl part of the substituted alkenyl group is the same as the above alkenyl group. Examples of substituted alkenyl groups include styryl and 4-methoxystyryl. The alkynyl part of the substituted alkynyl group is the same as the above alkynyl group. Examples of substituted alkynyl groups include 4-butoxyphenylethynyl, 4-propylphenylethynyl and trimethylsilylethynyl.

In the present invention, the aromatic group means an aryl group and a substituted aryl group. The number of carbon atoms in the aryl group is preferably 6-30, more preferably 6-20, and most preferably 6-10. Examples of the aryl group include phenyl, 1-naphthyl and 2-naphthyl. Examples of the substituent of the substituted aryl group include a halogen atom, a nitro group, a sulfonic acid group, an aliphatic group, an aromatic group, a heterocyclic group, —O—R ₇₁ , —S—R ₇₂ , —CO—R _73. , -O-CO-R ₇₄ , -CO-O-R ₇₅ , -O-CO-O-R ₇₆ , -NR ₇₇ R ₇₈ , -CO-NR ₇₉ R ₈₀ , -NR ₈₁ -CO-R ₈₂ , _{-O-CO-NR 83 R 84} , include -SiR ₈₅ R ₈₆ R ₈₇ R ₈₈ and _{-O-SiR 89 R 90 R 91} R 92.

_R71 , _R72 , _R73 , _R74 , _R75 , _R76 , _R77 , _R78 , _R79 , _R80 , _R81 , _R82 , _R83 , _R84 , _R85 , _R86 , _R87 , R ₈₈ , R ₈₉ , R ₉₀ , R ₉₁ and R ₉₂ are each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group.

  The aryl part of the substituted aryl group is the same as the above aryl group. Examples of substituted aryl groups include p-biphenylyl, 4-phenylethynylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 2- Propoxyphenyl, 3-propoxyphenyl, 4-propoxyphenyl, 2-butoxyphenyl, 3-butoxyphenyl, 4-butoxyphenyl, 2-hexyloxyphenyl, 3-hexyloxyphenyl, 4-hexyloxyphenyl, 2-octyloxy Phenyl, 3-octyloxyphenyl, 4-octyloxyphenyl, 2-dodecyloxyphenyl, 3-dodecyloxyphenyl, 4-dodecyloxyphenyl, 2-tetracosyloxyphenyl, 3-tetracosyloxyphenyl, 4- Tet Cosyloxyphenyl, 3,4-dimethoxyphenyl, 3,4-diethoxyphenyl, 3,4-dihexyloxyphenyl, 2,4-dimethoxyphenyl, 2,4-diethoxyphenyl, 2,4-dihexyloxyphenyl 3,5-dimethoxyphenyl, 3,5-dimethoxyphenyl, 3,5-dihexyloxyphenyl, 3,4,5-trimethoxyphenyl, 3,4,5-triethoxyphenyl, 3,4,5-tri Hexyloxyphenyl, 2,4,6-trimethoxyphenyl, 2,4,6-triethoxyphenyl, 2,4,6-trihexyloxyphenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-bromophenyl, 3-bromo Enyl, 4-bromophenyl, 3,4-difluorophenyl, 3,4-dichlorophenyl, 3,4-dibromophenyl, 2,4-difluorophenyl, 2,4-dichlorophenyl, 2,4-dibromophenyl, 3,5 -Difluorophenyl, 3,5-dichlorophenyl, 3,5-dibromophenyl, 3,4,5-trifluorophenyl, 3,4,5-trichlorophenyl, 3,4,5-tribromophenyl, 2,4, 6-trifluorophenyl, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, pentafluorophenyl, pentachlorophenyl, pentabromophenyl, 2-iodophenyl, 3-iodophenyl, 4-iodophenyl 2-formylphenyl, 3-formylphenyl, 4-formylphenyl, 2-ben Zoylphenyl, 3-benzoylphenyl, 4-benzoylphenyl, 2-carboxyphenyl, 3-carboxyphenyl, 4-carboxyphenyl, o-tolyl, m-tolyl, p-tolyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2- (2-methoxyethoxy) phenyl, 3- (2-methoxyethoxy) phenyl, 4- (2-methoxyethoxy) phenyl, 2-ethoxycarbonylphenyl, 3-ethoxycarbonylphenyl, 4-ethoxy Carbonylphenyl, 2-benzoyloxyphenyl, 3-benzoyloxyphenyl and 4-benzoyloxyphenyl are included.

  In the present invention, the heterocyclic group may have a substituent. The heterocyclic ring of the heterocyclic group is preferably a 5-membered ring or a 6-membered ring. The heterocyclic ring of the heterocyclic group may be condensed with an aliphatic ring, an aromatic ring or another heterocyclic ring. Examples of heteroatoms in the heterocycle include B, N, O, S, Se and Te. Examples of the heterocyclic group include a pyrrolidine ring, a morpholine ring, a 2-bora-1,3-dioxolane ring, and a 1,3-thiazolidine ring. Examples of the unsaturated heterocyclic ring include imidazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzotriazole ring, benzoselenazole ring, pyridine ring, pyrimidine ring and quinoline ring. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the substituted aryl group.

The molecular weight of the compound having a triphenylene ring is preferably 300 to 2,000. The boiling point of the compound is preferably 260 ° C. or higher. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Electronics Industry Co., Ltd.). Specific examples of R corresponding to the following general formula (2) of the compound in which 6 substituents of R _{1 to} R _{6 in} the general formula (1) have the same triphenylene ring are shown below.

  As R, (B-1) fluoro, (B-2) chloro, (B-3) bromo, (B-4) formyl, (B-5) benzoyl, (B-6) carboxyl, (B-7) ) Butylamino, (B-8) dibenzylamino, (B-9) trimethylsilyloxy, (B-10) 1-pentynyl, (B-11) ethoxycarbonyl, (B-12) 2-hydroxyethoxycarbonyl, B-13) Phenoxycarbonyl, (B-14) N-phenylcarbamoyl, (B-15) N, N-diethylcarbamoyl, (B-16) 4-methoxybenzoyloxy, (B-17) N-phenylcarbamoyloxy (B-18) hexyloxy, (B-19) 4-hexyloxybenzoyloxy, (B-20) ethoxy, (B-21) benzoyloxy, (B-22) -Dodecyloxyphenylthio, (B-23) t-octylthio, (B-24) p-fluorobenzoylthio, (B-25) isobutyrylthio, (B-26) p-methylbenzenesulfinyl, (B-27) ethane Sulfinyl, (B-28) benzenesulfonyl, (B-29) methanesulfonyl, (B-30) 2-methoxyethoxy, (B-31) propoxy, (B-32) 2-hydroxyethoxy, (B-33) 2-carboxyethoxy, (B-34) 3-heptenyloxy, (B-35) 2-phenylethoxy, (B-36) trichloromethoxy (B-37) 2-propynyloxy, (B-38) 2,4- Octadiynyloxy, (B-39) perfluoropentyloxy, (B-40) ethoxycarbonylmethoxy, (B-41) -Methoxyphenoxy, (B-42) m-ethoxyphenoxy, (B-43) o-chlorophenoxy, (B-44) m-dodecyloxyphenoxy, (B-45) 4-pyridyloxy, (B-46) Pentafluorobenzoyloxy, (B-47) p-hexyloxybenzoyloxy, (B-48) 1-naphthoyloxy, (B-49) 2-naphthoyloxy, (B-50) 5-imidazolecarbonyloxy, (B-51) o-phenoxycarbonylbenzoyloxy, (B-52) m- (2-methoxyethoxy) benzoyloxy, (B-53) o-carboxybenzoyloxy, (B-54) p-formylbenzoyloxy, (B-55) m-ethoxycarbonylbenzoyloxy, (B-56) p-pivaloylbenzoyloxy, (B-57) propionyloxy, (B-58) phenylacetoxy, (B-59) cinnamoyloxy, (B-60) hydroxyacetoxy, (B-61) ethoxycarbonylacetoxy, (B-62) m-butoxy Phenylpropioroyloxy, (B-63) propioroyloxy, (B-64) trimethylsilylpropioroyloxy, (B-65) 4-octenoyloxy, (B-66) 3-hydroxypropionyloxy, (B -67) 2-methoxyethoxyacetoxy, (B-68) perfluorobutyryloxy, (B-69) methanesulfonyloxy, (B-70) p-toluenesulfonyloxy, (B-71) triethylsilyl, (B -72) m-butoxyphenoxycarbonylamino, (B-73) hexyl, (B-7) ) Phenyl, (B-75) 4-pyridyl, (B-76) benzyloxycarbonyloxy, (B-77) m-chlorobenzamide, may be mentioned (B-78) 4-methylanilino like.

Specific examples of R corresponding to the following general formula (3) of the compound having 5 R and 6 identical R triphenylene rings among the R _{1 to} R ₆ substituents of the above general formula (1) It is shown below.

  R includes (B-79) nitro, (B-80) sulfo, (B-81) formyl, (B-82) carboxyl, (B-83) methoxycarbonyl, (B-84) benzyloxycarbonyl, B-85) Phenoxycarbonyl can be mentioned.

Specific examples of R corresponding to the following general formula (4) of compounds having the same R triphenylene ring in which R _{1 in the} general formula (1) is a hydroxyl group and five substituents R _{2 to} R ₆ are as follows: Show.

  Examples of R include (B-86) butoxy, (B-87) hexyloxy, (B-88) dodecyloxy, (B-89) hexanoyloxy, and (B-90) carboxymethoxy.

As a further example of R ₁ to R ₅ in the general formula (1), is the following B-91~B100.

  The addition amount of the compound having at least two aromatic rings and a compound having a compound in which at least two aromatic rings have a planar structure is 0 in the dope of the cellulose ester from the viewpoint of preventing bleed out. It is preferable to mix 4 to 10% by mass, and a range of 1.5 to 10% by mass is more preferable. Moreover, as a quantity to contain in a cellulose-ester film, 0.01-20 mass% is preferable with respect to 100 mass parts of cellulose sels, 5-30 mass% is further preferable, and 8-30 mass% is especially preferable.

  It is preferable that the cellulose ester film contains a deterioration inhibitor such as an antioxidant or a radical scavenger for preventing the cellulose ester film used in the liquid crystal display device according to the present invention from deteriorating.

  As the degradation inhibitor, hindered phenol compounds are preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl). -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- ( , 5-di-t-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5 -Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate Etc. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

  Further, in order to prevent the cellulose ester film according to the present invention from being deteriorated by ultraviolet rays, it is preferable to contain an ultraviolet absorber that cuts or weakens ultraviolet rays poured into the liquid crystal display device in addition to the above-described deterioration preventing agent. As the ultraviolet absorber, those which are excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and have little absorption of visible light having a wavelength of 400 nm or more are preferable from the viewpoint of liquid crystal display properties. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small. For example, Tinuvin 109, Tinuvin 171, Tinuvin 326, Tinuvin 327, Tinuvin 328, etc. manufactured by Ciba Specialty Chemicals can be preferably used. Depending on the amount used, a low molecular weight UV absorber may be formed in the same manner as a plasticizer. Therefore, the added amount is 0.01 to 5% by mass, preferably 0.13 to 3% by mass with respect to the cellulose ester. Some of these ultraviolet absorbers have at least two aromatic rings useful in the present invention, and at least two aromatic rings overlap with a compound having a planar structure.

  In the present invention, the cellulose ester film preferably contains fine particles. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, and hydration. It is preferable to contain inorganic fine particles such as calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and crosslinked polymer fine particles. Of these, silicon dioxide is preferable because it can reduce the haze of the film. The average particle size of the secondary particles of the fine particles is in the range of 0.01 to 1.0 μm, and the content is preferably 0.005 to 0.3% by mass with respect to the cellulose ester. In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such a material is preferable because the haze of the film can be reduced. Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes (particularly alkoxysilanes having a methyl group), silazane, siloxane and the like. The larger the average particle size of the fine particles, the greater the mat effect, and on the contrary, the smaller the average particle size, the better the transparency. Therefore, the average particle size of the preferred primary particles is 5 to 50 nm, more preferably 7 to 16 nm. It is. These fine particles are usually present as aggregates in the cellulose ester film, and it is preferable to form irregularities of 0.01 to 1.0 μm on the surface of the cellulose ester film. Examples of the fine particles of silicon dioxide include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc. manufactured by Aerosil, preferably AEROSIL (Aerosil) 200V, R972, R972V, R974, R202, and R812. Two or more kinds of these fine particles may be used in combination. When using 2 or more types together, it can mix and use in arbitrary ratios. In this case, fine particles having different average particle sizes and materials, for example, AEROSIL (Aerosil) 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9 to 0.1. In the present invention, the fine particles may be dispersed together with cellulose ester, other additives, and an organic solvent at the time of preparing the dope, but in a sufficiently dispersed state like a fine particle dispersion separately from the cellulose ester solution. It is preferable to prepare the dope. In order to disperse the fine particles, it is preferably preliminarily dispersed in an organic solvent and then finely dispersed by a disperser (high pressure disperser) having a high shearing force. After that, it is preferable to disperse in a larger amount of organic solvent, merge with the cellulose ester solution, and mix with an in-line mixer to obtain a dope. In this case, an ultraviolet absorbent may be added to the fine particle dispersion to form an ultraviolet absorbent liquid.

  The deterioration inhibitor, the ultraviolet absorber and / or the fine particles may be added together with the cellulose ester and the solvent during the preparation of the cellulose ester solution, or may be added during or after the solution preparation.

  Organic solvents useful for forming the dope according to the present invention simultaneously dissolve cellulose ester, compounds having at least two aromatic rings, and at least two aromatic rings having a planar structure, and other additives. If it does, it can be used without limitation. For example, as a chlorine organic solvent, methylene chloride, as a non-chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used. Particularly preferred is methyl acetate.

  In addition to the organic solvent, the dope according to the present invention preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, facilitating peeling from the metal support, and when the proportion of alcohol is small, the role of promoting dissolution of cellulose esters in non-chlorine organic solvent systems There is also. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferable because the dope has a relatively low boiling point, a relatively low boiling point, good drying properties, and no toxicity.

  The concentration of the cellulose ester in the dope is preferably adjusted to 15 to 40% by mass, and the dope viscosity is preferably adjusted to a range of 100 to 500 poise (P) in order to obtain good film surface quality.

  A plasticizer can be added to the dope according to the present invention. As the plasticizer, phosphate ester plasticizers, phthalate ester plasticizers, glycolate plasticizers, citrate ester plasticizers, and the like can be preferably used. As phosphate ester plasticizer, the above-mentioned triphenyl phosphate (TPP), tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., as phthalate ester plasticizer , Diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, citrate ester, acetyl triethyl citrate, acetyl tributyl citrate, glycolate Plasticizers include alkylphthalyl alkyl glycolate, butyl oleate, methyl ricinoleate Cetyl, dibutyl sebacate, triacetin or the like can be mentioned. In the present invention, a glycolate plasticizer can be preferably used. Examples of the alkylphthalylalkyl glycolate alkyl include alkyl groups having 1 to 8 carbon atoms. Preferred glycolate plasticizers include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate (EPEG), propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl Glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl For example, methyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate, methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycol Rate and octyl phthalyl octyl glycolate are preferable, and ethyl phthalyl ethyl glycolate is particularly preferable. These alkyl phthalyl alkyl glycolates may be used in combination of two or more.

  The addition amount of the alkyl phthalyl alkyl glycolate is preferably 1 to 10% by mass with respect to the cellulose ester from the viewpoint of reducing adhesion and suppressing bleed out from the film. In the present invention, the above-mentioned other plasticizers may be mixed together with the alkylphthalylalkyl glycolate.

<< Polarizing plate and liquid crystal display device >>
The cellulose ester film of the present invention maintains a stable performance as an optical compensation film that expands the viewing angle of a liquid crystal display device at the same time as a polarizing plate protective film by ensuring suitable retardation and slow axis characteristics. Can be used.

  The polarizing plate of the present invention will be described.

  The polarizing plate of the present invention can be produced by a general method. For example, there is a method in which the optical compensation film of the present invention is bonded to both surfaces of a polarizing film prepared by immersing and stretching in an iodine solution after alkali saponification treatment using a completely saponified polyvinyl alcohol aqueous solution. The alkali saponification treatment is a treatment in which the cellulose ester film is immersed in a strong alkaline solution at high temperature in order to improve the wetness of the aqueous adhesive and improve the adhesion.

  In the polarizing plate of the present invention, the light transmission axis of the polarizer containing the dichroic substance and the stretching direction in the width direction during casting of the polymer film to be bonded to the polarizer are substantially the same. It is preferable to bond so that it may become parallel. In the present invention, orthogonal means that the axes are substantially orthogonal as described above, and that the directions are the same means that the directions of the axes are substantially parallel. Indicates.

  A conventionally well-known thing can be used as a polarizer used for the polarizing plate of this invention. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol is treated with a dichroic dye such as iodine and stretched, or a plastic film such as vinyl chloride is treated and oriented. The polarizer thus obtained is bonded to a cellulose ester film.

  At this time, the optical compensation film of the present invention is used for at least one of the cellulose ester films. Another cellulose ester film can be used on the other surface. The cellulose ester film produced for the polymer film of the present invention may be used on the other side, or a commercially available cellulose ester film (KC8UX2MW, KC4UX2MW, KC5UN (manufactured by Konica Minolta Opto)) may be used. It can be used as a polarizing plate protective film on the other surface. In addition to the antiglare layer or the clear hard coat layer, the polarizing plate protective film used on the surface side of the display device preferably has an antireflection layer, an antistatic layer, and an antifouling layer. The antireflection layer (silicon oxide layer, titanium oxide layer), antistatic layer, and antifouling layer is preferably provided by a method such as coating, sputtering, CVD, atmospheric pressure plasma CVD, or vacuum deposition.

  The liquid crystal display device of the present invention can be produced by arranging and bonding the polarizing plate of the present invention obtained on the both sides of the liquid crystal cell.

  Moreover, when producing a polarizing plate, it is preferable to bond so that the slow axis of the polymer film of this invention and the transmission axis of a polarizer may become parallel. As a result, light leakage at the time of black display is remarkably improved, and even a liquid crystal display device having a large screen of 15 type or more, preferably 19 type or more, has no white spots at the periphery of the screen, and the effect thereof. It is maintained for a long time, and a remarkable effect is recognized particularly in a VA liquid crystal display device.

  In the polymer film of the present invention, an optically anisotropic layer using a liquid crystal compound can be further formed as required, and a liquid crystal display device employing various driving methods such as TN, VA, OCB, HAN, etc. The viewing angle characteristics can be optimized.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

  First, methods for measuring various physical properties are collectively described below.

(Measurement of cellulose ester film substitution degree)
The degree of substitution of acetyl (DSa) and the degree of substitution of propionyl (DSp) were measured according to ASTM-D817-96. Degree of substitution (DSa) is the number of all OH groups in a cellulose ester molecule that has been reacted with acetic acid and substituted, and is expressed in glucopyranose units. A value of 3 is taken.

(Measurement of Ro, Rt, slow axis angle, maximum tilt angle of slow axis)
The average refractive index of the sample was determined using an Abbe refractometer. Further, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), the birefringence is measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and the obtained phase difference is measured. Refractive indexes nx, ny, and nz were calculated from the values and average refractive index, and Ro and Rt values were determined from the above formulas (I) and (II). In addition, the slow axis angle and the maximum tilt angle of the slow axis were measured.

  Slow axis angle: The stretching direction of the cellulose ester film was taken as the reference line (0 degree), and the angle formed by the slow axis and the reference line was determined.

  Maximum tilt angle of slow axis: This refers to the maximum absolute value of the slow axis angle.

<< Preparation of dope >>
(Preparation of dope A)
1 part by weight Aerosil R972 and 9 parts by weight of ethanol are mixed in a container, finely dispersed with a Manton Gorin disperser having a shearing force of 30 MPa to form a fine particle stock solution, and diluted with 9 parts by weight of methylene chloride in a pressure-resistant sealed container The filler dispersion was diluted.

  14.2 parts by mass of methylene chloride and 1.2 parts by mass of an ultraviolet absorber (Tinuvin 109 / Tinuvin 171 (Ciba Specialty Chemicals Co., Ltd.) in a mass ratio of 1: 1) and 0.7 parts by mass of cellulose The ester (described in A of Table 1) was dissolved, and 3.0 parts by mass of the filler dispersion diluent was added and stirred to obtain a filler additive solution. The following cellulose ester solution composition was introduced into another pressure-resistant airtight container, and a cellulose ester solution was prepared by a high temperature dissolution method. The pressure inside the pressure-tight airtight container was set to 0.2 MPa and dissolved while stirring. Next, 0.04 parts by mass of the filler addition solution was poured into a cellulose ester solution having a mass of 1.0, and the mixture was sufficiently stirred and allowed to stand overnight. Thereafter, the solution was added to Azumi Filter Paper NO. Filtered using 244 to prepare Dope A.

(Cellulose ester solution composition)
Cellulose ester (described in Table 1A) 100 parts by mass TPP 8.5 parts by mass EPEG 2 parts by mass Methylene chloride 300 parts by mass Ethanol 57 parts by mass In the same manner, Dopes B to F were prepared in the configuration described in Table 1.

  Further, the following dopes G and H were prepared.

(Preparation of dope G)
The ultraviolet absorber at the time of preparing the dope D was changed to the following compound D, and 5 parts by mass of the compound D was added to 100 parts by mass of the cellulose ester, and a dope G was prepared in the same manner as in the preparation of the dope D.

<Compound D>
The following composition is put into a four-necked flask (installed with an inlet, a thermometer, a reflux condenser, a nitrogen inlet, and a stirrer), gradually heated to 80 ° C., and polymerized for 5 hours while stirring. After completion, the polymer solution was poured into a large amount of methanol to precipitate, further washed with methanol, purified and dried to obtain a compound having a weight average molecular weight of 2,000 (measured by GPC).

Methyl acrylate 10 parts by weight 2-hydroxyethyl acrylate 1 part by weight AIBN 2 parts by weight Toluene 30 parts by weight (Preparation of dope H)
The ultraviolet absorber at the time of preparing the dope A was changed to the following compound E, and 3.5 parts by mass of the compound E was added to 100 parts by mass of the cellulose ester, and a dope H was prepared in the same manner as in the preparation of the dope A.

(Production of optical compensation film)
Using the dope A, the dope temperature was adjusted to 35 ° C. and the support temperature was 35 ° C., and cast from a die onto a stainless steel support belt. The drying air temperature on the support was 40 ° C. Thereafter, the temperature of the support was set to 20 ° C., and the web was peeled from the support with a residual solvent amount of 80% by mass. Next, the film is stretched under the conditions of a stretching ratio of 1.3 times, a web temperature of 120 ° C. during stretching, and a web residual solvent of 20% during stretching while holding both ends of the web with clips using a tenter. On the other hand, it was relaxed by 1.5%. Next, from a state where the residual solvent of the web is 8%, while keeping the conveyance tension uniformly at 100 N / m, drying is performed while relaxing in the width direction with 500 rolls at a drying temperature of 80 ° C., a length of 5000 m, a width of 1. A roll-shaped optical compensation film 1 having a thickness of 4 m and a thickness of 60 μm was obtained. This film was knurled by applying an embossing roll having a width of 10 mm and an embossing height of 13 μm to both ends.

  Similarly, roll-shaped optical compensation films 2 to 8 were obtained using the dopes B to H.

  As a comparative example, at the time of producing the roll-shaped optical compensation films 1 to 8, after stretching 20% in total in two steps, the clip was opened without relaxation, and the conveyance tension was set to 90 to 110 N / m in that state. And it dried at the drying temperature of 80 degreeC, and produced the comparative optical compensation films 9-16.

  About the produced optical compensation films 1-16, the slow axis maximum inclination angle was calculated | required by the said measuring method from retardation Ro, Rt, and the slow axis angle, respectively, and the result was shown in following Table 2.

(Preparation of viewing angle compensation polarizing plate)
Roll-shaped optical compensation film 1 and cellulose triacetate film (manufactured by Konica Minolta Opto, model name 8UX; thickness = 80 μm) were each treated in a 2 mol / l sodium hydroxide aqueous solution at 60 ° C. for 2 minutes and washed with water Then, it was dried at 100 ° C. for 10 minutes to produce an alkali saponification polarizing plate protective film.

  Separately, a 120 μm-thick polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer (polarizing film).

  On both sides of the polarizer, a 5% aqueous solution of completely saponified polyvinyl alcohol is used as an adhesive, and the above-mentioned alkali saponified cellulose triacetate film is bonded to one side, and the optical compensation film 1 subjected to alkali saponification is bonded to the opposite side, A viewing angle compensation polarizing plate 1 was produced. At this time, bonding was performed such that the transmission axis of the polarizer and the slow axis of the optical compensation film 1 were parallel.

  Similarly, viewing angle compensation polarizing plates 2 to 16 were prepared using the optical compensation films 2 to 16.

<< Evaluation of VA liquid crystal display >>
The viewing angle compensation polarizing plates of the present invention and the comparative example obtained above were peeled off the optical compensation film and the polarizing plate previously bonded to the 15-inch liquid crystal display VL-150SD manufactured by Fujitsu, and the viewing angles of the present invention and the comparative example. Bonding was performed so that the absorption axis of the angle-compensating polarizing plate was the same as the absorption axis of the polarizing plate that had been bonded in advance, to produce display devices 1 to 16, and the following evaluations were performed.

(Viewing angle characteristics and durability)
For the evaluation of viewing angle characteristics, the transmitted light amount during black display and white display was measured using EZ-contrast manufactured by ELDIM. The viewing angle was evaluated by calculating contrast = (transmitted light amount during white display: cd / cm ² ) / (transmitted light amount during black display: cd / cm ² ).

  The durability of the viewing angle function was evaluated by measuring the viewing angle characteristics before and after 500 h treatment at 60 ° C. and 90% RH, and observing the change in angle indicating the viewing angle of contrast 10.

  The obtained results are shown in Table 2.

  From the above table, it was found that the liquid crystal display device using the optical compensation film of the present invention with respect to the comparative example is a display device having excellent viewing angle characteristics and high durability. Further, it was found that the degree of substitution of cellulose ester and the molecular weight distribution are within the preferred ranges of the present invention, and an optical compensation film using a compound having at least two aromatic rings is more excellent and preferable.

Claims (2)

A cellulose ester having 2.3 ≦ X + Y ≦ 2.85 and 1.4 ≦ X ≦ 2.85 when the acetyl substitution degree is X and the substitution degree of propionyl group or butyryl group is Y, In forming a film having an in-plane retardation Ro of 20 to 70 nm and a thickness direction retardation Rt of 70 to 400 nm and a width of 1.3 m to 4 m represented by the following formula, The film is stretched in the range of 1.05 to 1.5 times in the direction, and the film residual solvent amount is 5 to 30% by mass, and the temperature is 40 to 150 ° C., and the tension is 30 to 300 N / m . and dried while conveying a roll, an optical compensation film characterized in that relative to the extending direction of the film line as (0 °), the angle of the slow axis and the reference line to within 0.7 degrees in the film the whole width Manufacturing method.
(I) Ro = (nx−ny) × d
(II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film) Is the thickness of.) The number average molecular weight (Mn) of the cellulose ester is 80000-200000, the value of weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.4-3.0, and relative to 100 parts by mass of the cellulose ester The method for producing an optical compensation film according to claim 1, further comprising 0.01 to 20 parts by mass of a compound having at least two aromatic rings.