JP2002210766A - Method for producing cellulose ester film, cellulose ester film, polarizing plate and display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cellulose ester film with less stain on a peeling roll, and a cellulose ester film having less curl and high tear strength by the production method, a polarizing plate and a display using the same. Provide equipment. SOLUTION: When the compound has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is X, and the degree of substitution of a propionyl group or a butyryl group is Y, the above formula (I)
A) a solution casting film forming method using a dope containing at least one cellulose ester including a cellulose ester which simultaneously satisfies (a) and (II) and an organic solvent, and having a solid concentration of 21% by mass or more; A method for producing a cellulose ester film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cellulose ester film, a cellulose ester film, a polarizing plate using the same, and a display device using the same.

[0002]

2. Description of the Related Art In recent years, thin and lightweight notebook personal computers have been developed. Along with this, the demand for thinner and higher performance protective films for polarizing plates used in liquid crystal displays or organic EL displays has been increasing. Generally, a triacetyl cellulose film is widely used as a protective film for a polarizing plate,
Higher scratch resistance is required for thinning.

[0003] Triacetylcellulose films are used to improve the slipperiness (blocking resistance) and the scratch resistance.
For example, JP-A-62-37113 and JP-A-61-94
As described in, for example, Japanese Patent No. 725, it is known that various particles and the like are contained or applied. For example, Japanese Patent Application Laid-Open No. 7-11055 proposes fine particles having a methyl group on the surface and an adding method, and describes a method for preventing aggregation of the fine particles. However, when a large amount of fine particles are added to the film in order to increase the slip property, the slip property is improved and the scratch resistance is improved, but there is a problem that the turbidity indicating the clearness of the film is deteriorated,
It was still insufficient for use as a polarizing plate protective film requiring sufficient scratch resistance and sufficient clearness.

In Japanese Patent Application Laid-Open No. 9-90101, the use of an optical film made of a fatty acid cellulose ester having an acetic acid group and a propionic acid group improves heat resistance, wet heat resistance, and reduces optical distortion due to curl and the like. Methods for obtaining less polarizing films are known.

However, the curl of the obtained cellulose ester film is not sufficiently reduced even when the above-mentioned technique is used, the tear strength is not sufficient, and when the cellulose ester film is produced, dirt adheres to the release roll. Some problems were found. Thus, there has been a demand for a solution to the above problems.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a cellulose ester film with less soiling of a peeling roll, and a cellulose ester film having a low curl and a high tear strength by the production method. And a display device using the same.

[0007]

The above objects of the present invention have been attained by the following items 1 to 16.

[0008] 1. Assuming that the acyl group having 2 to 4 carbon atoms is a substituent, the degree of substitution of an acetyl group is X, and the degree of substitution of a propionyl group or a butyryl group is Y, the above formulas (Ia) and (II) A cellulose ester film produced by a solution casting method using a dope containing at least one cellulose ester containing a cellulose ester and an organic solvent, wherein the dope has a solid content of 21% by mass or more. Producing a cellulose ester film having a concentration, casting the dope on a support, forming a web (dope film), and peeling the web (dope film) from the support. Method.

[0009] 2. The formula (Ia) is the same as the formula (Ib)
2. The method for producing a cellulose ester film as described in 1 above, wherein

[0010] 3. 3. The method for producing a cellulose ester film as described in 1 or 2, wherein the organic solvent contains methylene chloride.

4. The dope is composed of a plasticizer A having a melting point of 25 ° C. or more and a plasticizer B having a melting point of less than 25 ° C. in a total of 1-2.
4. The method for producing a cellulose ester film according to any one of the above items 1 to 3, which contains 0% by mass.

5. The method for producing a cellulose ester film according to any one of the above items 1 to 4, wherein the dope contains an ultraviolet absorber having a melting point of 20 ° C or less.

6. The method for producing a cellulose ester film according to any one of the above items 1 to 5, wherein the dope contains fine particles.

7. 20H of cellulose ester film
7. The method for producing a cellulose ester film according to any one of the above items 1 to 6, wherein the absolute value of impedance at z is 4 × 10 ⁵ Ω or more.

[8] After the web (dope film) is peeled from the support, the web (dope film) is dried from a state in which the residual solvent amount is 35% by mass or less, while applying a tenter, until the residual solvent amount becomes 10% by mass or less. The method for producing a cellulose ester film according to any one of the above items 1 to 7, comprising a step.

9. 9. The method for producing a cellulose ester film according to any one of the above items 1 to 8, wherein a web (doped film) is formed on a support at a transport speed of 30 to 150 m / min.

10. Wherein the dry thickness of the cellulose ester film is 20 to 65 μm.
10. The method for producing a cellulose ester film according to any one of items 9 to 9.

11. 11. The web according to any one of items 1 to 10, wherein the web (dope film) is peeled from the support at a peeling tension of 190 N / m or less and further dried at a transporting tension of 190 N / m or less. A method for producing a cellulose ester film.

[12] 12. The method for producing a cellulose ester film according to any one of the above items 1 to 11, wherein Y is a degree of substitution of a propionyl group.

13. 13. A cellulose ester film produced by the production method according to any one of 1 to 12.

14. A polarizing plate comprising the cellulose ester film according to 13 above.

15. 15. A display device comprising the polarizing plate according to 14 above. Hereinafter, the present invention will be described in detail.

The process for producing a cellulose ester film of the present invention has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is X, and the degree of substitution of a propionyl group or a butyryl group is Y. As the formula (I-
a) a cellulose ester that simultaneously satisfies (II)
Dissolved in an organic solvent to make a cellulose ester dope,
This is a method for producing a cellulose ester film formed by a solution casting method using the dope, and is characterized in that the concentration of solids in the dope is adjusted to 21.0% by mass or more. The solid content in the dope is a cellulose ester,
It represents a constituent dissolved in an organic solvent such as an additive.

More preferably, a cellulose ester which satisfies the above-mentioned formulas (Ib) and (II) at the same time is used, and particularly preferably, a cellulose ester having an acetyl substitution degree X of less than 2.0 is used. A cellulose ester film formed by a membrane method and a method for producing the same.

The cellulose as a raw material of the cellulose ester according to the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp (derived from softwood or hardwood), and kenaf. Cellulose esters obtained therefrom can be mixed and used at an arbitrary ratio. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), the cellulose ester according to the present invention uses an organic acid such as acetic acid or an organic solvent such as methylene chloride. , Using a protic catalyst such as sulfuric acid.

When the acylating agent is acid chloride (CH ₃ COC)
1, 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 with reference to the method described in JP-A-10-45804 and the like. Further, the cellulose ester according to the present invention is prepared by mixing and reacting the amount of the acylating agent according to each degree of substitution, and reacted.
In the cellulose ester, these acyl groups react with the hydroxyl groups of the cellulose molecule.

The cellulose molecule is composed of a number of linked glucose units, and the glucose unit has three hydroxyl groups. The number of these three hydroxyl groups substituted with an acyl group is called the degree of substitution. For example, in cellulose triacetate, an acetyl group is bonded to all three hydroxyl groups of a glucose unit (actually, 2.6 to 3.0).

Examples of the cellulose ester according to the present invention include cellulose acetate having a propionate group or a butyrate group in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate. No. The butyryl group forming butyrate may be linear or branched.

Cellulose acetate propionate containing a propionate group as a substituent has excellent water resistance and is useful as a film for a liquid crystal display.

The method for measuring the degree of substitution of the acyl group is ASTM-
It can be measured according to the provisions of D817-96.

The number average molecular weight of the cellulose ester according to the present invention is preferably from 70,000 to 250,000, and it is preferable that the molded article has a high mechanical strength when molded and has an appropriate dope viscosity, and more preferably 80,000. ~ 150,
000.

The organic solvent according to the present invention is preferably capable of dissolving a cellulose ester and having an appropriate boiling point. For example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3- Dioxolan, 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, 1,
Examples thereof include 3-dimethyl-2-imidazolidinone, and organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate, and acetone are preferable organic solvents (ie, good solvents).

Further, as shown in the following film forming step, when the solvent is dried from the web (doped film) formed on the support in the solvent evaporation step, it is used from the viewpoint of preventing foaming in the web. The boiling point of the organic solvent
The boiling point of the good solvent described above is, for example, methylene chloride (boiling point 40.4 ° C), methyl acetate (boiling point 56.32 ° C), acetone (56.3).
° C) and ethyl acetate (76.82 ° C).

Among the above-mentioned good solvents, methylene chloride and methyl acetate which are excellent in solubility are preferably used.
In particular, it is preferable that methylene chloride is contained in an amount of 50% by mass or more based on the whole organic solvent.

In addition to the above organic solvent, 0.1 to 30% by mass
It is preferable to include an alcohol having 1 to 4 carbon atoms. Particularly preferably, the alcohol is contained in an amount of 10 to 30% by mass.

In these methods, after the dope described above is cast on a casting support, when the solvent starts to evaporate and the ratio of alcohol increases, the web (dope film) gels, and the web becomes durable. It is used as a gelling solvent for facilitating exfoliation, and when these are in a small proportion, it also has a role of promoting the dissolution of the cellulose ester of the non-chlorine organic solvent.

As the alcohol having 1 to 4 carbon atoms,
Methanol, ethanol, n-propanol, iso-
Propanol, n-butanol, sec-butanol,
Tert-butanol and the like can be mentioned.

Of these, ethanol is preferred because of its stability, the boiling point is relatively low, the drying property is good, and there is no toxicity. Further, it is preferable to use a solvent containing 15 to 30% by mass of ethanol with respect to 70 to 85% by mass of methylene chloride. To avoid solvents containing halogens due to environmental restrictions, methyl acetate can be used instead of methylene chloride.

Using the above-mentioned cellulose ester and an organic solvent, a film is formed as follows. In the present invention, the cellulose ester solution is called a cellulose ester dope or simply a dope.

The film forming step used in the method for producing a cellulose ester film of the present invention comprises the following dissolving step:
It comprises a casting step, a solvent evaporation step, a peeling step, a drying step and a winding step. Hereinafter, each step will be described.

<< Dissolving Step >> This is a step of forming a dope by dissolving the flakes in cellulose ester flakes in a dissolving vessel in an organic solvent mainly composed of a good solvent as described above while stirring the flakes.

In the present invention, the solid content concentration in the dope is 2
1.0% by mass or more, and the solid content concentration in the dope is 2%.
By adjusting the content to 1.0% by mass or more, a film with less curl can be obtained and the roll stain during the production can be significantly reduced. However, in order to further obtain the effect, the solid content concentration is 22.0% by mass. Or more, more preferably 23% by mass or more.

The upper limit of the solid content concentration in the dope is not particularly limited. However, if the concentration is too high, the viscosity of the dope becomes too high, and shark skin or the like may be formed at the time of casting to deteriorate the film flatness. % By mass is the upper limit.

The dope viscosity is preferably adjusted in the range of 10 to 50 Pa · s. The dissolution may be carried out at normal pressure, at a temperature below the boiling point of the preferred organic solvent (ie, good solvent) as described above, at a pressure above the boiling point of the good solvent described above, or by a cooling dissolution method. There are various dissolving methods and the like, such as a method of performing the method and a method of performing a high pressure. As a method of dissolving at a temperature not lower than the boiling point of a good solvent and applying a pressure that does not boil, 0.14 to 120 ° C. and 0.11 to 1.50 MPa
By applying a pressure to a, foaming can be suppressed and dissolution can be achieved in a short time.

The solvent used in the dissolving step according to the present invention may be used alone or in combination. However, it is preferable to use a mixture of a good solvent and a poor solvent from the viewpoint of production efficiency. The mixing ratio of the good solvent is 70 to 95% by mass, and the poor solvent is 30 to 5% by mass.
It is.

The good solvent and the poor solvent used in the present invention are:
Those that dissolve the cellulose ester used alone are defined as good solvents, and those that swell or do not dissolve alone are defined as poor solvents. Therefore, the good solvent and the poor solvent vary depending on the amount of bound acetic acid of the cellulose ester. For example, when acetone is used as a solvent, a good solvent is obtained when the amount of bound acetic acid of the cellulose ester is 55%, and the amount of bound acetic acid is 6%.
At 0%, it becomes a poor solvent.

In dissolving the cellulose ester, it is also possible to first dissolve the cellulose ester using a good solvent and a part of a poor solvent, and then add the remaining poor solvent. As the poor solvent used in the present invention,
For example, methanol, ethanol, n-butanol, cyclohexane and the like are preferably used.

As a cooling dissolution method, for example,
No. 95538, No. 9-95544, No. 9-95557
The method described in the above item can be used. Further, the high-pressure melting method described in JP-A-11-21379 can also be preferably used.

After dissolution, the dope is preferably filtered with a filter medium, defoamed, and sent to the next step by a pump. At this time, a plasticizer, an antioxidant, a dye, a matting agent, etc. are also added to the dope. May be done.

These compounds may be added together with the cellulose ester and the solvent when preparing the cellulose ester solution, or may be added during or after the solution is prepared.

For a liquid crystal display device, it is preferable to add a plasticizer, an antioxidant, an ultraviolet absorber, a matting agent, etc. for imparting heat and moisture resistance.

As the above-mentioned antioxidant, hindered phenol compounds are preferably used.
-Butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5 -Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-
3,5-di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (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)
And isocyanurate. Especially 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, a hydrazine-based metal deactivator such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-
A phosphorus-based processing stabilizer such as (di-t-butylphenyl) phosphite may be used in combination. The amount of addition of these compounds is 1 ppm to
1.0% is preferable, and 10 to 1000 ppm is more preferable.

In addition, heat stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, and salts of alkaline earth metals such as calcium and magnesium are added. You may.

Further, antistatic agents, flame retardants, lubricants, oils and the like can be added. << Casting Process >> A dope is fed to a pressurized die through a pressurized metering gear pump and, at a casting position, a casting support for an endless metal belt or a rotating metal drum that is transported infinitely (hereinafter simply referred to as a support). This is a step of casting a dope from a pressure die. The surface of the casting support is a mirror surface.

Other casting methods include a doctor blade method in which the thickness of the cast dope film is adjusted with a blade, and a reverse roll coater method in which the dope film is adjusted with a counter-rotating roll. A pressure die that can adjust the shape and easily make the film thickness uniform is preferable. Pressure dies include coat hanger dies and T dies.
Both are preferably used.

In order to increase the film forming speed, two or more pressure dies may be provided on the casting support, and the doping amount may be divided to form a plurality of layers. In the method for producing a cellulose ester film of the present invention, from the viewpoint of producing a film having a dry film thickness of 20 to 65 μm, it is preferable to adjust the film forming speed of the dope on the support to 30 m / m or more. From the viewpoint of obtaining a film having particularly good flatness,
The film forming speed is preferably adjusted to 30 to 150 m / min.

<< Solvent Evaporation Step >> A web (in the present invention, a dope is cast on a casting support and the formed dope film is called a web) is heated on the casting support to remove the solvent. This is the step of evaporating. In order to evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat with liquid from the back surface of the support and a method of transferring heat from the front and back by radiant heat. Drying efficiency is preferred. A method of combining them is also preferable.

<< Peeling Step >> In this step, the web from which the solvent has evaporated on the support is peeled from the support at the peeling position. The peeled web is sent to the next step.

If the residual solvent amount (the following formula) of the web at the time of peeling is too large, it is difficult to peel the web. On the contrary, if the web is sufficiently dried on the support and then peeled, a part of the web peels in the middle. Or

The temperature at the peeling position on the support is preferably 10 to 40 ° C., more preferably 11 to 30 ° C.
° C. Further, from the viewpoint of facilitating peeling, the amount of the residual solvent of the web at the peeling position is preferably 20 to 100% by mass, and more preferably 40 to 90% by mass.

The residual solvent amount of the web according to the present invention is defined by the following equation. Residual solvent amount = (mass before heat treatment of web−mass after heat treatment of web) / (mass after heat treatment of web) × 100% The heat treatment when measuring the amount of residual solvent is 115
This means that heat treatment is performed at 1 ° C. for 1 hour.

In order to adjust the amount of the residual solvent at the time of peeling as described above, the surface temperature of the casting support after casting is controlled so that the organic solvent can be efficiently evaporated from the web. It is preferable to set the temperature at the peeling position on the casting support within the above-mentioned temperature range. In order to control the temperature of the support, a heat transfer method having good heat transfer efficiency is preferably used. For example, a back surface heat transfer method using a liquid is preferable.

It is difficult to control the temperature of the support by the heat transfer method using radiant heat, hot air, or the like, and it is not a preferable method. However, in a belt (support) machine, it is necessary to control the temperature at the place where the belt to be transferred comes below. Can adjust the belt temperature with gentle wind.

The temperature of the support can be partially changed by dividing the heating means, so that the temperature of the support is different at the casting position, drying section, peeling position, etc. of the casting support. Can be done.

As a method of increasing the film forming speed (the film forming speed can be increased because the film is separated while the amount of the residual solvent is as large as possible), there is a gel casting method in which the film can be separated even if the amount of the residual solvent is large. .

There are a method of adding a poor solvent for the cellulose ester into the dope, casting the dope and then gelling, and a method of gelling by lowering the temperature of the support.

There is also a method of adding a metal salt to the dope. By gelling on the support and strengthening the membrane,
It is possible to accelerate the peeling and increase the film forming speed.

In the case where the web is peeled off at a point where the residual solvent amount is larger, if the web is too soft, the flatness at the time of peeling is impaired, and the peeling tension tends to cause shearing and vertical streaks. The amount of solvent can be determined.

The peeling force when the film is peeled off from the support is usually 196 to 245 N / m. However, the content of the ultraviolet absorber per unit mass of the cellulose ester is large, and it is higher than the conventional one. Since the cellulose ester film of the present invention having a thin film is easily wrinkled at the time of peeling, it is preferable that the cellulose ester film is peeled at 190 N / m or less, and further, the minimum peelable tension is 166.6 N / m.
m, then peeling at a minimum tension of ２137.2 N / m, particularly preferably at a minimum tension of １００100 N
/ M. It is preferable that the peeling tension is lower because the in-plane retardation R0 can be kept low. The in-plane retardation R0 is preferably less than 20 nm, more preferably less than 10 nm and then preferably less than 5 nm, most preferably 0 to 1 nm.

In the present invention, the in-plane retardation R
0 was measured using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) at a wavelength of 590 nm.
A three-dimensional refractive index measurement is performed, and the obtained refractive indices nx, ny,
nz can be calculated. Further, the retardation value Rt in the thickness direction is preferably less than 150 nm, particularly preferably more than 40 nm and less than 80 nm.

The cellulose ester film of the present invention comprises
The angle θ (radian) between the slow axis direction and the film forming direction and the in-plane retardation R0 have the following relationship, and are particularly preferably used as a support for a polarizing plate protective film or an optical compensation film.

P ≦ 1−sin ² (2θ) × sin ² (πR0 / λ) P is 0.999, and λ is the wavelength of light of 590 nm at the time of three-dimensional refractive index measurement for obtaining R0 and θ. θ (radian) is the angle between the long direction (film forming direction) of the film and the slow axis direction. More preferably, P is 0.9999
Satisfies the above relationship, and more preferably P satisfies the above relationship at 0.99995.

<Drying Step> While maintaining the width using a drying device that alternately transports the web through rolls arranged in a staggered manner and / or a tenter device that transports the web while holding both ends of the web with clips or pins, This is the step of drying the web. It is preferable to maintain the transport tension in the drying step as low as possible, because R0 can be kept low, and it is preferably 190 N / m or less. It is more preferably 170 N / m or less, more preferably 140 N / m or less, more preferably 100 N / m or less.
It is particularly preferred that the pressure is from 130 N / m to 130 N / m. In particular, it is effective to maintain the transport tension at or below the above-mentioned value until the amount of the residual solvent in the film becomes at least 5% by mass or less.

As for drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying microwaves instead of wind. Too fast drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed when the residual solvent is about 8% by mass or less. Throughout the whole, the drying temperature is preferably 40 to 250 ° C.,
More preferably, it is 70 to 180 ° C.

The drying temperature, the amount of drying air and the drying time vary depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.

In the drying step after peeling from the casting support surface, the web tends to shrink in the width direction due to evaporation of the solvent.

The more the material is rapidly dried at a high temperature, the greater the shrinkage. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the resulting film.

From this viewpoint, for example, Japanese Patent Application Laid-Open No. Sho 62-46
No. 625, a method of drying the whole or a part of the web in the width direction while holding both ends of the web width with a clip or a pin (called a tenter method), in particular, a tenter using a clip A pin tenter method using a pin is preferably used.

Incidentally, it was found that the effect of reducing the curl of the film obtained by drying while holding the width as described above was obtained. At this time, the stretching ratio in the width direction is preferably × 1.00 to × 1.10.
More preferably, it is 1.03 to 1.07. When the tenter is performed, the residual solvent amount of the web is preferably 35% by mass or less at the start of the tenter, and it is preferable to perform drying while applying a tenter until the residual solvent amount of the web becomes 10% by mass or less. , More preferably 5% by mass or less.

In the drying step of the cellulose ester film, the film peeled off from the support is further dried to reduce the residual solvent amount to preferably 3% by mass or less, more preferably 0.5% by mass or less. is there.

In the film drying step, a roll hanging method or a method of drying while transporting the film by the pin tenter method as described above is generally employed. For liquid crystal display members, it is preferable to dry while maintaining the width by a pin tenter method in order to improve dimensional stability.
In particular, it is particularly preferable to maintain the width at a place where the amount of the residual solvent is large immediately after peeling off from the support, since the effect of improving the dimensional stability is further exhibited. The means for drying the film is not particularly limited, and is generally performed using hot air, infrared rays, a heating roll, a microwave, or the like. It is preferable to use hot air in terms of simplicity. It is preferable that the drying temperature is divided into three to five stages in the range of 40 to 150 ° C. and is gradually increased.
It is more preferable to carry out in the range of 140 ° C. in order to improve dimensional stability.

<< Winding Step >> This is a step of winding up the cellulose ester film after the amount of the residual solvent in the web becomes 2% by mass or less.
A film having good dimensional stability can be obtained by the following.

As the winding method, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with constant internal stress, and the like. .

The thickness of the cellulose ester film varies depending on the purpose of use, but as a finished film, it is usually in the range of 5 to 500 μm, and more preferably 20 to 250 μm.
Is preferable, and as a film for a liquid crystal image display device, the range is preferably 20 to 120 μm, and more preferably 20 to 65 μm.
A cellulose ester film having a thickness of μm is particularly preferred.

To adjust the film thickness, the dope concentration, the amount of liquid supplied by the pump, the slit gap of the die cap, the extrusion pressure of the die, the speed of the casting support, etc. are controlled so as to obtain the desired thickness. Good to do.

Further, as means for making the film thickness uniform, it is preferable that the programmed feedback information is fed back to each of the above-mentioned devices using a film thickness detecting means for adjustment. 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, but 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 evaporated solvent in the dry atmosphere must always be considered.

The cellulose ester film of the present invention preferably contains a plasticizer. The plasticizer according to the present invention will be described.

As the plasticizer according to the present invention, phosphate esters and carboxylate esters are preferably used.
In the present invention, it is particularly preferable that the melting point contains a plasticizer having a melting point of 25 ° C. or lower. Further, it is preferable that the cellulose ester film contains a plasticizer having a melting point of less than 25 ° C. and a plasticizer having a melting point of 25 ° C. or more. .

The plasticizer is not particularly limited. Examples of the phosphate ester plasticizer include triphenyl phosphate (TPP) and tricresyl phosphate (TC).
P), biphenyl-diphenyl phosphate, dimethylethyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

Representative carboxylic acid ester plasticizers include phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP) and diethylhexyl phthalate (DEH).
P), ethylphthalylethyl glycolate and the like are used.

As the citrate ester plasticizer, acetyl triethyl citrate (OACTE) and acetyl tributyl citrate (OACTB) are used.

As the glycolic acid ester plasticizer,
It is preferable to use triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate or the like alone or in combination.

Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic esters.

In the present invention, it is particularly preferable to use a phosphate ester-based plasticizer and a plasticizer having a melting point of less than 25 ° C. in combination, because of excellent dimensional stability and water resistance.

The plasticizer having a melting point of less than 25 ° C. according to the present invention is not particularly limited as long as it has a melting point of less than 25 ° C., and can be selected from the above plasticizers. For example, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, diethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, triacetin, ethyl phthalyl ethyl glycolate and the like can be mentioned. It is preferable to use these plasticizers alone or in combination.

The plasticizer having a melting point of less than 25 ° C. used in the present invention preferably has a melting point of -5 to 25 ° C.

As the plasticizer having a melting point of 25 ° C. or higher according to the present invention, for example, diethoxyethyl phthalate (melting point 3
4 ° C.), triphenyl phosphate (melting point 48.5)
℃), benzophenone (melting point 48 ° C), camphor (melting point 15
2 ° C.), o-cresyl-p-toluenesulfonate (5
2.5 ° C.), cyclohexyl-p-toluenesulfonamide (86 ° C.), methylbenzoylbenzoate (52
° C) and ethylbenzoylbenzoate (melting point 58 ° C).

The melting point in the present invention refers to the true freezing point described in the Chemical Encyclopedia published by Kyoritsu Shuppan Co., Ltd. as the melting point.

The amount of these plasticizers to be used is 1 to 1 with respect to cellulose ester in terms of film performance, processability and the like.
15% by mass is preferred. For a liquid crystal display member, the content is more preferably 5 to 15% by mass, particularly preferably 7 to 12% by mass, from the viewpoint of dimensional stability. In the present invention, the total content of the plasticizer having a melting point of 25 ° C. or more and the plasticizer having a melting point of less than 25 ° C. in the cellulose ester film is preferably 1 to 20% by mass.

Further, the content of the plasticizer having a melting point of less than 25 ° C. with respect to the cellulose ester film is 1 to 10% by mass.
Is more preferable, and more preferably, it is 3-7 mass%.

It is preferable that the proportion of the plasticizer having a melting point of less than 25 ° C. in the total plasticizer is large, because the flexibility of the cellulose ester film is improved and the processability is excellent.

It is preferable to use a plasticizer having a melting point of less than 25 ° C. in an amount of 1% by mass or more based on the cellulose ester, since the flexibility of the cellulose ester film is improved and the processability is excellent. Use of a plasticizer having a temperature of less than 14 ° C. is preferred because the processability is further improved.

The workability is when slitting or punching a base film or a liquid crystal display member. If the workability is poor, the cut surface becomes saw-toothed and chips are generated. Is not preferred.

The ultraviolet absorbent for the cellulose ester film of the present invention will be described. The cellulose ester film of the present invention is used for a polarizing plate or a liquid crystal display member or the like because of its high dimensional stability, and an ultraviolet absorber is preferably used from the viewpoint of preventing deterioration of the polarizing plate or the liquid crystal or the like.

As the ultraviolet absorber, those having excellent absorption of ultraviolet light having a wavelength of 370 nm or less and little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specifically, the transmittance at 380 nm is preferably less than 10%, and more preferably less than 5%.

Specific examples of the ultraviolet absorber preferably used in the present invention include, for example, oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. Can be
Further, a polymer ultraviolet absorber described in JP-A-6-148430 is also preferably used.

As the benzotriazole-based ultraviolet absorber, a compound represented by the following general formula [1] is preferably used.

[0109]

Embedded image

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and include a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group, an alkoxyl group. group, an acyloxy group, an aryloxy group, an alkylthio group, an arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- to 6-membered heterocyclic group, the carbon of R ₄ and R ₅ are 5- or 6-membered ring closure A ring may be formed.

Further, these groups described above may have an arbitrary substituent. Hereinafter, specific examples of the ultraviolet absorbent according to the present invention will be described, but the present invention is not limited thereto.

UV-1: 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-
tert-butylphenyl) benzotriazole UV-3: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-
tert-butylphenyl) -5-chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ",
4 ", 5", 6 "-tetrahydrophthalimidomethyl)
-5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,
3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) UV-7: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol (TINUVIN171, Ciba) UV-9: octyl-3- [3-tert-butyl-4
-Hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole- 2
-Yl) phenyl] propionate mixture (TINU
(VIN109, manufactured by Ciba) Among the above, as an ultraviolet absorber having a melting point of 20 ° C. or less, UV-8 has a melting point of −56 ° C., and UV-9 has a yellow transparent viscous liquid at room temperature (25 ° C.). It is.

As the benzophenone-based ultraviolet absorber which is one of the ultraviolet absorbers according to the present invention, a compound represented by the following general formula [2] is preferably used.

[0114]

Embedded image

In the formula, Y represents a hydrogen atom, a halogen atom or an alkyl group, an alkenyl group, an alkoxyl group and a phenyl group, and these alkyl group, alkenyl group and phenyl group may have a substituent. A represents a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, an alkylcarbonyl group, an alkylsulfonyl group or a -CO (NH) _n-1 -D group, and D represents an alkyl group, an alkenyl group or a substituent. Represents a phenyl group which may have m and n represent 1 or 2.

In the above, the alkyl group represents, for example, a linear or branched aliphatic group having up to 24 carbon atoms, the alkoxyl group includes, for example, an alkoxyl group having up to 18 carbon atoms, and the alkenyl group includes, for example, An alkenyl group having up to 16 carbon atoms represents, for example, an allyl group or a 2-butenyl group. In addition, the alkyl group, the alkenyl group, as a substituent to the phenyl group, a halogen atom, for example, a chlorine atom, a bromine atom, a fluorine atom, a hydroxyl group,
And a phenyl group (this phenyl group may be substituted with an alkyl group or a halogen atom).

The specific examples of the benzophenone-based compound represented by the general formula [2] are shown below, but the present invention is not limited to these.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: bis ( 2-methoxy-4-hydroxy-5
-Benzoylphenylmethane) The above-mentioned ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber or a benzophenone-based ultraviolet absorber having high transparency and an excellent effect of preventing deterioration of a polarizing plate or a liquid crystal element. Preferably, a benzotriazole-based ultraviolet absorber having less unnecessary coloring is particularly preferably used.

The method for adding the ultraviolet absorbent additive liquid according to the present invention includes the following methods.

<< Addition Method A >> As a method for preparing an ultraviolet absorber additive liquid, an ultraviolet absorber is dissolved in an organic solvent such as alcohol, methylene chloride, or dioxolane, and then added directly to the dope composition.

<< Addition Method B >> As a method for preparing an ultraviolet absorbent additive liquid, an ultraviolet absorbent and a small amount of a cellulose ester are dissolved in an organic solvent such as alcohol, methylene chloride, or dioxolane, and then added to the dope with an in-line mixer. .

In the present invention, the addition method B is preferred because it can easily adjust the amount of the ultraviolet absorber added, and is excellent in productivity.

The amount of the UV absorber used is not uniform depending on the kind of the compound and the conditions of use, but is usually preferably 0.2 to 2.0 g, more preferably 0.4 to 1.5 g per 1 m ² of the cellulose ester film. Is more preferable, and 0.6-1.
0 g is particularly preferred.

Further, in the present invention, particularly, the melting point is 2
An ultraviolet absorber at 0 ° C. or lower is preferably used. Generally, ultraviolet absorbers are often poorly soluble,
It was found that the presence of a liquid plasticizer facilitated dissolution. Therefore, in the case of a configuration containing a plasticizer that is liquid at 25 ° C. inside, it is possible to sufficiently add an ultraviolet absorber and dissolve it with a margin, which is particularly effective when preparing a high-concentration dope. Further, it has become possible to provide a film having a sufficient ultraviolet absorbing ability. Furthermore, by incorporating an ultraviolet absorbent which is liquid at 20 ° C. and a plasticizer which is liquid at 25 ° C., a higher concentration of the ultraviolet absorbent and the plasticizer can be contained, and the film has excellent transparency. Moisture and ultraviolet absorbing ability can be imparted, and the effect of reducing the process contamination due to the precipitation of these additives was also obtained.

The fine particles according to the present invention will be described. Examples of the fine particles according to the present invention include fine particles of an inorganic compound and fine particles of an organic compound.

As the inorganic compound, a compound containing silicon,
Preferred are silicon dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate, more preferably containing silicon. Although inorganic compounds and zirconium oxide are used, silicon dioxide is particularly preferably used because turbidity of the cellulose ester laminated film can be reduced.

As the fine particles of silicon dioxide, for example, Aerosil R972, R972V, R974, R812,
200, 200V, 300, R202, OX50, TT
Commercial products such as 600 (all manufactured by Nippon Aerosil Co., Ltd.) can be used.

As the fine particles of zirconium oxide, commercially available products such as Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) can be used.

As the organic compound, for example, polymers such as silicone resin, fluorine resin and acrylic resin are preferable, and among them, silicone resin is preferably used.

Among the silicone resins described above, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 1
Commercial products having trade names such as Nos. 45, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.) can be used.

The primary average particle diameter of the fine particles according to the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, from the viewpoint of suppressing haze.
Particularly preferably, it is 5 to 12 nm.

The primary average particle diameter of the fine particles according to the present invention is measured by observing the particles with a transmission electron microscope (magnification: 500,000 to 2,000,000), observing 100 particles, and calculating the average value. The primary average particle diameter was used.

The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter.
g / liter, particularly preferably 100 to 200 g / l.
g / liter. As the apparent specific gravity is larger, it becomes possible to produce a high concentration dispersion, haze and aggregates are preferably improved, and when preparing a dope having a high solid content as in the present invention, Are particularly preferably used.

The fine particles of silicon dioxide having an average primary particle diameter of not more than 20 nm and an apparent specific gravity of not less than 70 g / liter are obtained, for example, by mixing a mixture of vaporized silicon tetrachloride and hydrogen.
It can be obtained by burning in air at 000 to 1200 ° C. Further, for example, they are commercially available under the trade names of Aerosil 200V and Aerosil R972V (all manufactured by Nippon Aerosil Co., Ltd.), and these can be used.

In the present invention, the apparent specific gravity described above was calculated by the following formula by measuring a certain amount of silicon dioxide fine particles in a measuring cylinder and measuring the weight at this time.

Apparent specific gravity (g / liter) = mass of silicon dioxide (g) / volume of silicon dioxide (liter) The method of preparing the dispersion of fine particles according to the present invention is as follows.
For example, there are three types as shown below.

<< Preparation Method A >> After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. The fine particle dispersion is added to the dope and stirred.

<< Preparation Method B >> After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. Separately, a small amount of cellulose triacetate is added to a solvent and dissolved by stirring. The fine particle dispersion is added thereto and stirred. This is used as a fine particle addition liquid. The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

<< Preparation Method C >> A small amount of cellulose triacetate is added to a solvent and dissolved by stirring. Fine particles are added thereto and dispersed by a disperser. This is used as a fine particle addition liquid.
The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are less likely to re-aggregate. Above all, the above-mentioned preparation method B is a preferable preparation method excellent in both the dispersibility of the silicon dioxide fine particles and the difficulty of re-aggregation of the silicon dioxide fine particles.

<< Dispersion Method >> When silicon dioxide fine particles are mixed with a solvent or the like and dispersed, the concentration of silicon dioxide is 5 to 30.
% By mass, more preferably 10 to 25% by mass, and most preferably 15 to 20% by mass. The higher the dispersion concentration, the lower the liquid turbidity with respect to the amount added, which is preferable because haze and aggregates are improved.

The solvent to be used is preferably a lower alcohol, preferably methyl alcohol, ethyl alcohol,
Examples thereof include propyl alcohol, isopropyl alcohol, and butyl alcohol. The solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used in forming a cellulose ester film.

The addition amount of the silicon dioxide fine particles to the cellulose ester is preferably 0.01 to 0.3 parts by mass, more preferably 0.05 to 0.2 parts by mass, based on 100 parts by mass of the cellulose ester. , 0.
08 to 0.12 parts by mass is most preferred. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the lower the haze and the smaller the agglomerates.

As the disperser, an ordinary disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing the silicon dioxide fine particles, a medialess disperser is preferable because the haze is low.

Examples of the media disperser include a ball mill, a sand mill, a dyno mill and the like.

As the medialess disperser, there are an ultrasonic type, a centrifugal type, a high-pressure type, and the like. In the present invention, a high-pressure disperser is preferable. The high-pressure dispersing device is a device that creates a special condition such as a high shear or a high pressure state by allowing a composition in which fine particles and a solvent are mixed to pass through a thin tube at a high speed. When processing with a high-pressure dispersion device, for example, a tube diameter of 1 to 2000 μm
The maximum pressure condition inside the device is 9.807MP
It is preferably at least a. More preferably, 19.6
13 MPa or more. At that time, the maximum arrival speed is 1
Over 100m / sec, heat transfer speed is 420kJ /
Those that reach more than an hour are preferred.

The high-pressure dispersion apparatus as described above includes Micro
There is an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Fluidics Corporation or a Nanomizer manufactured by Nanomizer, and a homogenizer of the Manton-Gaulin type such as a homogenizer manufactured by Izumi Food Machinery Co., Ltd .; 01 and the like.

Further, it is preferable to cast the layer containing the fine particles according to the present invention so as to be in direct contact with the casting support, since a film having high slip properties and low haze can be obtained.

The cellulose ester film of the present invention comprises
The absolute value of the impedance at a frequency of 20 Hz is 4 ×
It is preferably 10 ⁵ Ω or more, more preferably ⁵ Ω or more.
× 10 ^{5 to} 5 × 10 ²⁰ Ω, most preferably 8 × 10 ⁵ to 1
× 10 ¹⁴ Ω.

As is well known, the conductivity of a material can be a cation,
It is expressed by charge carriers present in the particles such as anions, electrons, and holes, and becomes a solid electrolyte when the main charge carriers are ions, and becomes a semiconductor when the charge carriers are electrons.

Further, when the conductivity was examined in detail, as shown in the following well-known general formula (A), if the conductivity of the material increased, the absolute value of the impedance Z including the resistance term was generally obtained. It is well known that the value decreases.

General formula (A) | Z | = [R ² + (1 / ωC) ² ] ^1/2 where Z: impedance R: resistance C: capacitance ω: 2πf f: frequency In the present invention, the film Regarding the impedance measurement of a material, a general impedance measurement device used for measuring the dielectric constant of an electronic component can be used, but preferably, an impedance measurement device capable of measuring a frequency of 1 Hz or more, and a device combining a film measurement electrode. It is.
For example, Yokogawa Hewlett-Packard Precision LCR meters HP4284A and HP16451B
It is a combination of When using another device, it is necessary to correct the electrode portion.

In order to obtain the effects described in the present invention, it is necessary to correctly measure the impedance of the film material. Therefore, if an uncorrectable device is used, a favorable result cannot be obtained. An example of obtaining the absolute value of the impedance at 20 Hz using this combination of devices will be described in detail. If the absolute value of the impedance at a frequency of 20 Hz of the film material can be accurately measured, the present invention does not limit the measuring method.

23 ° C., 20% using a precision LCR meter HP4284A connected to an HP16451B having two electrodes composed of parallel planes and a guard electrode.
Under an RH atmosphere, the absolute value of the impedance of the film material is measured by a gap method.

Regarding the measurement by the void method, HP16451
Follow the electrode non-contact method described in the instruction manual for B.
The size of the sample is not particularly limited as long as it is larger than the electrode plane, but when the diameter of the main electrode is 3.8 cm, a square sample having a size of 6 cm × 6 cm to 5 cm × 5 cm is preferable. If the surface resistivity measured using the direct current of the sample is the same on the front and back, either side may be up, but if the front and back are not equal, the surface with low surface resistivity is turned up. A sample is placed between two electrodes composed of parallel planes, and measurement is performed by a gap method while applying an AC voltage.

The preferred range measured is that the absolute value of the impedance at a frequency of 20 Hz measured using an electrode having an area of 11 to 12 cm ² is 4 × 10 ⁵ Ω or more, preferably 5 × 10 ⁵ Ω or more and 5 × 10 ²⁰ Ω. Ω or less, more preferably 8 × 10 ⁵ Ω or more and 1 × 10 ¹⁴ Ω or less.

An optical film having a preferable impedance can be obtained by adding a substance having conductivity. The conductive substance is not particularly limited, but an ionic conductive substance, conductive fine particles, an antistatic agent compatible with cellulose ester, or the like can be used.

Here, the ionic conductive substance is a substance which exhibits electric conductivity and contains ions which are carriers for carrying electricity, and examples thereof include ionic polymer compounds.

The ionic polymer compound is disclosed in
9-23828, 49-23827, 47-2
Anionic polymer compounds as found in No. 8937;
JP-B-55-7334, JP-A-50-54672, JP-B-59-14735, JP-B-57-18175, and JP-A-57-18175.
Ionene-type polymers having a dissociating group in the main chain, such as those described in JP-A Nos. 7-18176 and 57-56059; Japanese Patent Publication Nos. 53-13223 and 57-15376.
No., JP-B No. 53-45231, and No. 55-145783
No. 55-65950, No. 55-67746, No. 57-11342, No. 57-19735, Japanese Patent Publication No. 5
8-56858, JP-A-61-27853, 62
And cationic pendant polymers having a cationic dissociating group in the side chain, such as those described in US Pat.

Examples of the conductive fine particles include conductive metal oxides. Examples of metal _{oxides, ZnO, TiO 2, SnO 2} , Al 2 O 3, In 2 O 3,
_{SiO 2, MgO, BaO, MoO} 2, V 2 O 5 or the like, or composite oxides thereof are preferred, in particular ZnO, TiO ₂
And SnO ₂ are preferred. Examples including heteroatoms include
For example, for ZnO, addition of Al, In, etc., TiO ₂
It is effective to add Nb, Ta and the like to SnO ₂ , and to Sb, Nb and a halogen element to SnO ₂ . The addition amount of these hetero atoms is 0.01 mol% to 25 mol%.
mol% is preferable, but 0.1 mol% to 15 m
ol% is particularly preferred.

The volume resistivity of these conductive metal oxide powders is 10 ⁷ Ωcm or less, particularly 10 ⁵ Ωcm or less, the primary particle diameter is 10 nm or more and 0.2 μm or less, and the It is preferable that powder having a specific structure whose major axis is 30 nm or more and 6 μm or less is contained in at least a part of the film in a volume fraction of 50% or less, more preferably 0.01% to 20%. %.

Particularly preferably, JP-A-9-203810
It is desirable to contain an ionene conductive polymer described in the above publication or a quaternary ammonium cation conductive polymer having an intermolecular crosslink.

The characteristic of the crosslinked cationic conductive polymer lies in the obtained dispersible granular polymer, which has a high concentration and high density of the cation component in the particles, and therefore has excellent conductivity. Not only does it show no deterioration in conductivity even under low relative humidity, and the particles have good adhesion in the film formation process after casting, even though the particles are well dispersed in a dispersed state. Therefore, it has high film strength, and also has excellent adhesiveness to other substances such as a resin of a support, and has excellent chemical resistance.

The dispersible particulate polymer which is a cross-linkable cationic conductive polymer generally has a particle size of about 0.01 μm to 0.3 μm.
m, preferably from 0.05 μm to
Particle sizes in the range of 0.15 μm are used. As used herein, the term "dispersible granular polymer" refers to a clear or slightly hazy solution by visual observation,
A polymer that appears as a particulate dispersion under an electron microscope.

In the present invention, the ratio of the fine particles to the cellulose ester is preferably 1 to 10 parts by mass with respect to 1 part by mass of the fine particles, and it is preferable that the addition amount is small in terms of transmittance and haze.

The addition of an antistatic agent or a matting agent is preferably contained in the surface layer (a portion 10 μm from the surface) of the optical film. The antistatic agent and / or matting agent is added to the surface of the film by a method such as co-casting. It is preferable to include a matting agent. Specifically, a dope A containing a conductive material and / or a matting agent and a dope B containing substantially no such dope are used, and the dope B is cast so that the dope A is present on at least one surface of the dope B. Is preferred.

An example of the method for producing the cellulose ester film of the present invention will be described with reference to the process charts shown in FIGS.

FIG. 1 is a process diagram showing an example of the apparatus for producing a cellulose ester film of the present invention, and FIG. 2 is a sectional view of the slit die 6 shown in FIG.

The cellulose ester of the present invention can be produced as a single-layer film, but is preferably produced as a laminated film by applying a co-casting method or the like.

Hereinafter, the steps for producing a laminated film by the co-casting method will be described, but the present invention is not limited thereto.

A dope solution 1a is charged into a dope solution tank 1 for preparing a cellulose ester dope solution.
The fine particle addition liquid tank 2 is charged with the fine particle addition liquid 2a.

The dope solution 1a is sent to the in-line mixers 5a and 5b by the sending pumps 4b and 4c, and the fine particle addition solution 2a is sent to the in-line mixer 5 by the pump 4a.
a. Dope solution 1 with in-line mixer 5a
a and the fine particle addition liquid 2a are sufficiently mixed, and the slit die 6
Is sent to the slit 13.

Similarly, the dope solution 1a and the ultraviolet absorber additive solution 3a are sufficiently mixed by the in-line mixer 5b and sent to the slit 12 of the slit die 6.

The layers on the upper and lower surfaces from the slit die 6 are composed of a mixture of the dope liquid 1a and the fine particle addition liquid 2a, and the middle layer is a mixture of the dope liquid 1a and the ultraviolet absorbent addition liquid 3a. It is co-cast from the casting port 11 and cast on a casting belt 8 that moves continuously from the drum 7. After drying, the cast cellulose ester dope layer composed of three layers is separated from the casting belt by the roller 9 as the cellulose ester laminated film 10.

The co-casting method applicable to the production method of the present invention will be described. Co-casting is a sequential multi-layer casting method in which two or three layers are formed through different dies, and a simultaneous multi-layer casting method in which two or three slits are merged in a die having two or three slits. Alternatively, any of the multilayer casting methods combining the sequential multilayer casting and the simultaneous multilayer casting may be used.

The film thickness at the time of casting can be arbitrarily set.
The film thickness ratio of the dope on the A side (forming the skin layer on the A side) and the dope on the B side (forming the skin layer on the B side) is 1 to 1 after drying.
It is preferably in the range of 100 to 100: 1. More preferably, the ratio is 1:20 to 20: 1, and can be 1: 1. When one of the dopes is cast thinly, it is preferable to cast the dope so that the thinner wet film thickness (hw) is 0.5 to 150 μm and the dry film thickness is 0.1 to 30 μm, and more preferably wet. Film thickness (hw) 2.5-12
5 μm, dry film thickness 0.5 to 25 μm, more preferably wet film thickness (hw) 25 to 100 μm, dry film thickness 5
It is preferable that the casting be performed so that the thickness becomes 20 μm.

In the present invention, the dope on the B side indicates a dope in which the dope is in direct contact with the casting support, and the dope on the A side is on the side opposite to the surface in contact with the support. And / or a dope other than forming a surface layer and / or directly contacting the casting support.

When three types of dopes are used, the dope on the A side (formation of the surface layer on the A side) and the dope on the B side (formation of the surface layer on the B side) are used to form the inside of the film sandwiched therebetween. The doping (formation of the core layer) and the film thickness ratio after each drying can also be arbitrarily set. The thickness ratio of the core layer and the surface layer on the A side or the surface layer on the B side after drying is 1: 100 to 100.
The ratio is preferably in the range of 1 to 1, more preferably 1 to 20 to 1 and may be 1 to 1.

The dry thickness of the surface layer can be arbitrarily set, but it is preferably 0.5 to 30 μm, and 5 to 20 μm.
More preferably, it is μm. The film thickness of the surface layer on the side A and the surface layer of the surface B may be the same or different. For example, the surface layer on the side A may be 10 μm, and the surface layer on the side B may be 20 μm.

When two or more kinds of dopes are used, they may be cast on the support at the same time or may be separately cast on the support. When casting separately, the dope on the support side can be first cast and dried to some extent on the support, and then can be cast on top of it. When three or more dopes are used, simultaneous casting (also called co-casting) and sequential casting may be appropriately combined and cast to produce a film having a laminated structure.

In these methods of forming a film by simultaneous or sequential casting, unlike the method of coating on a dried film, the boundaries between the layers of the laminated structure become unclear, and the lamination is observed by observing the cross section. It has a feature that the structure may not be clearly separated, and has an effect of improving the adhesion between the layers.

The dry film thickness of the film produced by this method is not particularly limited, but it can be preferably used for producing a film of 20 to 65 μm.

As the cellulose ester used in the present invention, one having little luminescent spot foreign matter when formed into a film is particularly preferably used as a support for a polarizing plate protective film or an optical compensation film. In the present invention, the bright spot foreign matter refers to two polarizing plates arranged at right angles (crossed Nicols), a cellulose ester film is arranged therebetween, and light from a light source is applied from one surface to the other surface. When the cellulose ester film is observed from above, the light from the light source appears to leak.

At this time, the polarizing plate used in the evaluation is desirably formed of a protective film having no bright spot foreign matter, and a polarizing plate using a glass plate for protection of the polarizer is preferably used. It is thought that one of the causes of the generation of the bright spot foreign matter is unacetylated cellulose contained in the cellulose ester. As a countermeasure, it is possible to use a cellulose ester having a small amount of unacetylated cellulose or to use a cellulose ester. Removal and reduction can be achieved by filtering the dissolved dope solution or the like. Also, the smaller the film thickness, the smaller the number of bright spot foreign substances per unit area, and the smaller the content of cellulose ester contained in the film, the smaller the number of bright spot foreign substances.

It is preferable that the number of bright spot foreign matters having a bright spot diameter of 0.01 mm or more is 200 / cm ² or less.
More preferably, 100 / cm ² or less, 50 / cm ²
Hereinafter, 30 / cm ² or less, it is preferably 10 pieces / cm ² or less, and particularly preferably it is zero.

The number of luminescent spots of 0.005 to less than 0.01 mm is also preferably 200 / cm ² or less, more preferably 100 / cm ² or less, and 50 / cm ² or less.
cm ^2, 30 / cm ² or less, it is preferably 10 pieces / cm ² or less, particularly preferred is when the bright point is zero. It is preferable that the number of luminescent spots of 0.005 mm or less is small.

In the case of removing the bright spot foreign matter by filtration, it is preferable to filter a composition containing a mixed plasticizer and to remove the bright spot foreign matter, as compared with the case where a cellulose ester is dissolved alone, and then the composition is added. As the filter material, conventionally known materials such as glass fiber, cellulose fiber, filter paper, and fluororesin such as ethylene tetrafluoride resin are preferably used, but ceramics and metals are also preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 30 μm or less, and 10 μm or less.
Particularly preferably, it is 5 μm or less.

These can be used in appropriate combination. The filter medium may be either a surface type or a depth type, but the depth type is preferably used because it is relatively hard to clog.

The polarizing plate according to the present invention will be described. The polarizing plate according to the present invention can be manufactured by a general method. For example, there is a method in which a cellulose ester film of the present invention is alkali-treated, and is immersed and stretched in an iodine solution, and bonded to both surfaces of a polarizing film using a completely saponified polyvinyl alcohol aqueous solution. The alkali saponification treatment described above refers to a treatment in which a cellulose ester film is immersed in a high-temperature strong alkaline solution in order to improve the wettability of the aqueous adhesive at this time and improve the adhesiveness.

The polarizing film, which is a main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film currently known is a polyvinyl alcohol-based polarizing film. Are dyed polyvinyl alcohol-based films with iodine and dyed with dichroic dyes. These are formed by forming a film of an aqueous polyvinyl alcohol solution and uniaxially stretching and dyeing the film, or dyeing the film and then uniaxially stretching the film, and then preferably performing a durability treatment with a boron compound. A transparent plastic film, which is a protective film for a polarizing plate made of the cellulose ester film of the present invention, is laminated on the surface of the polarizing film to form a polarizing plate.

The cellulose ester film obtained as described above is excellent in transparency, optically isotropic, and has sufficient mechanical strength represented by tear strength.
In addition, since the curl is small, it is useful as an optical film, particularly a protective film for a polarizing plate, and can be appropriately subjected to antireflection processing, antistatic processing, clear hard coat processing, and antiglare processing.

[0192]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 << Preparation of Dope >> A predetermined amount of the material shown in Table 1 was charged into a pressurized airtight container, heated to 80 ° C., and the pressure in the container was adjusted to 2 atm. The other additives were completely dissolved to obtain a dope. Next, the temperature of the dope was lowered to a casting temperature, the solution was allowed to stand overnight, and after defoaming, the solution was subjected to Azumi Filter Paper No. 244, using each of the dopes 1 to 12 described in Table 1,
Prepared.

[0194]

[Table 1]

CAP (cellulose acetate propionate): acetyl substitution degree 2.0, propionyl group substitution degree 0.8, number average molecular weight 100,000 TAC (triacetyl cellulose): acetylation degree 61% (UV absorber A (the following three kinds of mixtures)) Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.3 kg Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 0.5 kg Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 0. 5 kg (UV absorber B (the following two kinds of mixture)) Tinuvin 326 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.5 kg Tinuvin 328 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.5 kg Plasticizer 1 (triphenyl phosphate, Melting point 48.5 ° C) 11 kg Plasticizer 2 (ethyl Lil ethyl glycolate, melting point less than 25 ° C) 4 kg Plasticizer 3 (a mixture of the following two) Triphenyl phosphate 7 kg Ethyl phthalyl ethyl glycolate 3 kg Matting agent F (Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.)) 0.1 kg Antistatic agent (P-1) 25kg

[0196]

Embedded image

<< Preparation of Cellulose Ester Films 1 and 2 >> Dope 1 and Dope 2 shown in Table 1 were each used and the apparatus shown in FIG. 1 (effective drying length of the support was 60 m). The temperature was adjusted to 35 ° C., and the film was cast from a die onto a support so that the film thickness after drying was as shown in Table 2.

The drying air temperature on the support was 40 ° C.
After about one round, the temperature of the support was set to 15 ° C., and the dry film was peeled off from the support. Next, while being roll-conveyed in an oven at 70 ° C., it is dried for 5 minutes,
It was further dried at 130 ° C. for 15 minutes to prepare cellulose ester films 1 and 2, respectively.

<< Preparation of Cellulose Ester Film 11 >> The dope shown in Table 2 was used to adjust the dope temperature to 35 ° C. and the support temperature to 35 ° C. by the apparatus shown in FIG. 1 (effective drying length of the support: 60 m). Then, the film was cast from a die onto a support so that the film thickness after drying was as shown in Table 2. The die shown in FIG. 2 was used, and the dope 3 was simultaneously cast on the support so as to sandwich the dope 3 with the dope 4.

The drying air temperature on the support was 40 ° C.
After about one round, the temperature of the support was set to 15 ° C., and the dry film was peeled off from the support. Next, while being roll-transferred in an oven at 70 ° C., it was dried for 2 minutes,
Further, the web was dried at 100 ° C. for 1 minute while maintaining the width with a tenter, and dried at 130 ° C. until the amount of the residual solvent in the web became 1% by mass or less, thereby producing a cellulose ester film 11.

After drying, the portion formed by the dope 3 has a thickness of 50 μm, and the portion formed by the dope 4 has a thickness of 5 μm.
Each time, the dry film thickness of the film was adjusted to 60 μm.

<< Preparation of Cellulose Ester Film 12 >> The cellulose ester film 11 was prepared in the same manner as above except that dope 8 was used in place of dope 3 and that dope 7 was used instead of dope 4 so as to be sandwiched therebetween.
Cellulose ester film 12 was produced in the same manner as described above.

<< Preparation of Cellulose Ester Films 3 to 10 and Preparation of Comparative Cellulose Ester Films 13 to 15 >> Using the dope described in Table 2, the dope was prepared by the apparatus shown in FIG. 1 (the effective drying length of the support was 60 m). The temperature was adjusted to 35 ° C. and the support temperature to 35 ° C., and the film was cast from the die onto the support so that the film thickness after drying was as shown in Table 2.

The drying air temperature on the support was 40 ° C.
After about one round, the temperature of the support was set to 15 ° C., and the dry film was peeled off from the support.

Next, the film separated from the support was gripped at both ends with a tenter and dried at 100 ° C. for 5 minutes. %, So that cellulose ester films 3 to 10 and comparative cellulose ester films 13 to 15 were prepared.

<< Cellulose Ester Films 16, 17
Preparation of Dope 11 and Dope 12 shown in Table 1 were respectively adjusted to a dope temperature of 35 ° C. and a support temperature of 35 ° C. by the apparatus of FIG. 1 (effective drying length of the support: 60 m).
The film was cast from a die onto a support so that the film thickness after drying was as shown in Table 2.

The drying air temperature on the support was 40 ° C.
After about one round, the temperature of the support was set to 15 ° C., and the dry film was peeled off from the support. Next, while being roll-conveyed in an oven at 70 ° C., it is dried for 5 minutes,
Then, while maintaining the width by the tenter, 100
The resultant was dried at 120 ° C. for 5 minutes, and further dried at 120 ° C. until the amount of the residual solvent in the web became 1% by mass or less, to produce cellulose ester films 16 and 17, respectively.

The obtained cellulose ester film sample was evaluated for roll contamination and the curl and tear strength of the obtained film were measured as described below. The results are shown in Table 2.

<< Measurement of Substitution Degree of Cellulose Ester >> A
It carried out according to the method prescribed | regulated to STM-D817-96.

<< Measurement of Number Average Molecular Weight of Cellulose Ester >> Measured by high performance liquid chromatography under the following conditions.

Solvent: acetone Column: MPW × 1 (manufactured by Tosoh Corporation) Sample concentration: 0.2 mass / v% Flow rate: 1.0 ml / min Sample injection volume: 300 μl Standard sample: polymethyl methacrylate (Mw = 188,2
00) Temperature: 23 ° C. << Measurement of tear strength of film >> JIS-K7128
The longitudinal direction (longitudinal direction) and the lateral direction (width direction) of the film were measured in accordance with the method specified in B, and expressed as an average value of both.

<< Measurement of Curl Value >>
After leaving for 48 hours in an environment of 55 ° C. and 55% RH, the film is cut into a longitudinal direction (film forming direction) of 2 mm and a width direction of 50 mm. Further, the film piece is kept at 23 ± 2 ° C., 55%
Condition for 24 hours under RH environment, using a curvature scale,
The radius of curvature having a curve matching the film was confirmed, and the radius of curvature (1 / m) was defined as the curl value of the film.

<< Evaluation Method of Roll Stain >> After producing a 15000 m cellulose ester film, the degree of soiling of the first roll in contact with the film peeled from the stainless steel band support was visually observed and evaluated according to the following ranks. did.

◎: The roll is not dirty at all ○: A very small part of the roll is slightly stained △: The roll is slightly stained entirely ×: The roll is completely stained ◎ Is the level at which the production is continued. X is the level at which the production is interrupted and the rolls need to be cleaned. The results obtained are shown in Table 2.

[0215]

[Table 2]

[0216] From Table 2, it can be seen that the production method of the present invention has less stain on the release roll, and the cellulose ester film obtained by the production method of the present invention has less curl and
It is clear that the tear strength is also excellent.

Further, the sample cellulose ester films 11 and 12 of the present invention had an absolute value of impedance of 10 ⁶ Ω or more at a frequency of 20 Hz, and had good surface quality and excellent flatness without streaking or the like. When a plasticizer having a melting point of 25 ° C. or more and a plasticizer having a melting point of less than 25 ° C. is used as a plasticizer, curling is reduced, and a UV absorber having a melting point of 20 ° C. or less is further contained. As a result, it was confirmed that roll contamination was reduced.

Example 2 The cellulose ester films 1 to 12, 16 and 17 and the comparative cellulose ester films 13 to 15 shown in Table 2 obtained in Example 1 were used as protective films for polarizing plates, respectively. A polarizing plate was prepared according to the above method, and the obtained polarizing plate was attached to a liquid crystal display, and the image quality was evaluated.

<< Preparation of Polarizing Film >> A polyvinyl alcohol film having a thickness of 120 μm was immersed in an aqueous solution containing 1 part of iodine, 2 parts of potassium iodide and 4 parts of boric acid, and stretched 4 times at 50 ° C. to form a polarizing film. Obtained.

<< Preparation of Polarizing Plate >> (1) As a protective film, two cellulose ester film samples cut in a length direction of 30 cm and a width direction of 18 cm were immersed in a 2 mol / l sodium hydroxide solution at 60 ° C. for 1 minute. And further washed with water and dried.

(2) The polarizing film described above, which was adjusted to the same size as the two cellulose ester film samples, had a solid content of 2
It is immersed for 1 to 2 seconds in a mass% polyvinyl alcohol adhesive tank.

(3) The excess adhesive adhering to the polarizing film was gently removed, placed on the B side of the cellulose ester film sample, and further bonded to the B side of another cellulose ester film sample and the adhesive. Are laminated and arranged so that

(4) Excess adhesive and air bubbles are removed from the end of the laminate of the polarizing film and the cellulose ester film laminated by a hand roller, and the laminate is bonded. The hand roller applied a pressure of 20 to 30 N / cm ² and the roller speed was about 2 m / min.

(5) The obtained sample was left in a dryer at 80 ° C. for 2 minutes to prepare a polarizing plate. Next, the obtained polarizing plate was incorporated into a liquid crystal panel as described below, and the characteristics as a display device were evaluated.

<< Evaluation of Characteristics as Display Device >> 15-inch TF
T-type color liquid crystal display LA-1529HM (NE
C) was peeled off, and each of the above-prepared polarizing plates was cut according to the size of the liquid crystal cell. With the liquid crystal cell interposed therebetween, the two polarizing plates prepared as described above are adhered so as to be orthogonal to each other so that the polarizing axes of the polarizing plates do not change from the original, and a 15-inch TFT color liquid crystal display is prepared. When the properties as a polarizing plate were evaluated, when the cellulose ester films 1 to 12, 16, and 17 of the present invention were used as a polarizing plate protective film, curling was small and the polarizing plate was easily manufactured. In addition, the edge portions did not peel off when the polarizing plate was cut, the flatness was good, and it was confirmed that the polarizing plate was excellent as a polarizing plate for an image display device such as a liquid crystal display.

Example 3 << Preparation of Dope >> The following materials were charged in predetermined amounts into a pressurized airtight container, heated to 80 ° C., and the pressure in the container was adjusted to 2 atm. The agent was completely dissolved to obtain a dope. Next, the temperature of the dope was lowered to a casting temperature, the solution was allowed to stand overnight, and after defoaming, the solution was subjected to Azumi Filter Paper No. Prepared by filtration using 244.

(Materials) methylene chloride 245 kg ethanol 82 kg CAP (cellulose acetate propionate: acetyl substitution degree 2.0, propionyl group substitution degree 0.8, number average molecular weight 100,000) 100 kg tinuvin 326 (Chiba Specialty Chemicals ( 0.5 kg Tinuvin 109 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.7 kg Tinuvin 171 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.7 kg triphenyl phosphate 3 kg ethylphthalylethyl glycolate 4 kg Aerosil R200V (Japan) Aerosil Co., Ltd.) 0.1 kg << Preparation of cellulose ester film >>
(The effective drying length of the support is 60 m), the dope temperature is adjusted to 35 ° C. and the support temperature is adjusted to 35 ° C., so that the film thickness after drying from the die onto the support is 5040 μm.
It was cast at 5 m. The drying air temperature on the support was 40 ° C. After about one round, the temperature of the support was set to 15 ° C,
Peeling tension 160 N / at a film forming speed of 30 m / min from the support
m. Next, the film is conveyed through a drying zone at 60 ° C. by a tenter so that the stretching ratio in the lateral direction becomes × 1.03 times, and dried until the residual solvent amount becomes less than 10%. After drying for minutes, a cellulose ester film was prepared. The transporting tension in the drying step was 100 N / m.

<< Measurement of Bright Spot Foreign Material >> Two polarizing plates are arranged in an orthogonal state (crossed Nicols) to block transmitted light, and the above-mentioned cellulose ester film is placed between the two polarizing plates. The polarizing plate used was a glass protective plate. Irradiate light from one side and 1c with optical microscope (50x) from the other side
The number of bright spots having a diameter of 0.01 mm or more per m ² was counted.

<< Measurement of Retardation Value (Rt, R0) and Slow Axis Angle >> Automatic Birefringence Meter KOBRA-21A
Samples 10 to 12 were measured using DH (manufactured by Oji Scientific Instruments).
The sample 8 in Example 1 was subjected to three-dimensional refractive index measurement at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and the slow axis angle θ and the refractive indices Nx, Ny, and Nz were determined. The retardation value Rt in the thickness direction and the retardation value R0 in the in-plane direction were calculated according to the following general formulas (1) and (2).

General formula (1) Rt value = ((Nx + Ny) / 2−Nz) × d General formula (2) R0 value = (Nx−Ny) × d In the formula, Nx is a slow axis direction in the film plane. Index of refraction, Ny
Is the refractive index in the fast axis direction in the film plane, Nz is the refractive index of the film in the thickness direction, and d is the thickness of the film (n
m).

In the same manner as in Example 1, the curl value, roll stain, and tear strength were examined. As a result, the curl was 10, the roll stain was 強度, and the tear strength was 11 g. The in-plane retardation R0 is 0.5 nm, the slow axis angle is 5 °,
Rt was 50 nm. The number of bright spot foreign substances having a diameter of 0.01 mm or more was 0 / cm ² .

According to the method described in Example 2, a polarizing plate and a display device were produced using the cellulose ester film of the present invention as a protective film for a polarizing plate. As a result, the cellulose ester film of the present invention had little curl and was easy to produce a polarizing plate. There was no peeling of the edges when the polarizing plate was cut, and the flatness was good. Further, it was confirmed that the display device manufactured using this polarizing plate had excellent contrast and was excellent as a polarizing plate for an image display device such as a liquid crystal display.

Example 4 << Preparation of Dope >> The following materials were charged in predetermined amounts into a pressurized airtight container, heated to 80 ° C., and the pressure in the container was adjusted to 2 atm. The agent was completely dissolved to obtain a dope. Next, the temperature of the dope was lowered to a casting temperature, the solution was allowed to stand overnight, and after defoaming, the solution was subjected to Azumi Filter Paper No. Prepared by filtration using 244.

(Materials) Methylene chloride 245 kg Ethanol 82 kg CAB (cellulose acetate butyrate): Degree of acetyl substitution 1.8, degree of butylyl substitution 0.7 100 kg Tinuvin 326 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.5 kg Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 0.7 kg tinuvin 171 (manufactured by Ciba Specialty Chemicals) 0.7 kg triphenyl phosphate 83 kg ethylphthalylethyl glycolate 4 kg Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.) 1 kg << Preparation of cellulose ester film >>
(The effective drying length of the support is 60 m), the dope temperature is adjusted to 33 ° C. and the support temperature is adjusted to 33 ° C., and the width of 1.5 m is adjusted so that the film thickness after drying from the die is 48 μm.
Was cast. The drying air temperature on the support was 38 ° C.
After about one round, the temperature of the support was set to 15 ° C., and the film was peeled from the support at a film forming speed of 30 m / min at a peeling tension of 160 N / m. Next, the film is transported in a drying zone at 60 ° C. by a tenter so that the stretching ratio in the horizontal direction becomes × 1.03 times, and dried until the residual solvent amount becomes less than 10%, and further at 115 ° C. for 15 minutes. After drying, a cellulose ester film was prepared. The transport tension in the drying process is 1
The test was performed at 20 N / m.

In the same manner as in Example 3, the curl value, roll stain, tear strength, retardation value, slow axis angle and bright spot foreign matter were examined. As a result, the curl was 12, the roll stain was ◎, and the tear strength was 9 g. . The in-plane retardation R0 is 1 nm, the slow axis angle is 10 °, and Rt is 4
It was 0 nm. No bright spot foreign matter with a diameter of 0.01 mm or more
Pieces / cm ² .

According to the method described in Example 2, a polarizing plate and a display device were produced using the cellulose ester film of the present invention as a protective film for a polarizing plate. As a result, the cellulose ester film of the present invention has little curl and is easily manufactured. Met. In addition, the edge portions did not peel off when the polarizing plate was cut, and the flatness was good. Further, it was confirmed that the display device using this polarizing plate was superior in contrast as compared with the comparative example, and was excellent as a polarizing plate for an image display device such as a liquid crystal display.

Example 5 The following composition was prepared.

<< Preparation of Coating Composition (1) (for Preparing Antistatic Layer) >> Diamond BR-108 (manufactured by Mitsubishi Rayon Co., Ltd.) 0.5 parts by mass Propylene glycol monomethyl ether 60 parts by mass Methyl ethyl ketone 20 parts by mass Lactic acid Ethyl 5 parts by mass Methanol 8 parts by mass Conductive polymer resin P-1 (average particle size 0.1 μm) 0.5 parts by mass << Preparation of coating composition (2) (for preparing clear hard coat layer) >> dipentaerythritol hexa Acrylate monomer 60 parts by mass Dipentaerythritol hexaacrylate dimer 20 parts by mass Components more than dipentaerythritol hexaacrylate trimer 20 parts by mass Dimethoxybenzophenone photoinitiator 4 parts by mass Ethyl acetate 50 parts by mass Methyl ethyl ketone 50 parts by mass 50 parts by mass of isopropyl alcohol Preparation of coating composition (3) (for preparing antiglare layer) >> 50 parts by mass of ethyl acetate 50 parts by mass of methyl ethyl ketone 50 parts by mass of isopropyl alcohol Sylysia 431 (average particle size 2.5 μm (manufactured by Fuji Silysia Chemical Ltd.)) Parts by mass Aerosil R972V (average particle size: 16 nm (manufactured by Nippon Aerosil Co., Ltd.)) 2 parts by mass Stir the above with a high-speed stirrer (TK homomixer, manufactured by Tokushu Kika Kogyo Co., Ltd.), and then use a collision type disperser (Menton) And the following components were added.

Dipentaerythritol hexaacrylate monomer 60 parts by mass Dipentaerythritol hexaacrylate dimer 20 parts by mass Dipentaerythritol hexaacrylate trimer or higher component 20 parts by mass Dimethoxybenzophenone photoreaction initiator 4 parts by mass << Coating Preparation of Composition (4) (for Backcoat Layer Preparation)> Acetone 32 parts by mass Ethyl acetate 50 parts by mass Isopropyl alcohol 4 parts by mass Diacetylcellulose 0.5 parts by mass Ultrafine silica (Aerosil R972V) 2% acetone dispersion (Japan 0.1 part by weight of the cellulose acetate propionate film prepared in Example 3 was coated with the coating composition (4) on one surface by a wet film thickness of 1
Extrusion coated to 3 μm, drying temperature 80 ° C
And dried. The coating composition (1) was applied to the other surface of the cellulose acetate propionate film by a wire bar coat at a transport speed of 30 m / min so as to have a wet film thickness of 9 μm, and was then set to 80 ° C. The resin was dried in a drying section to provide a resin layer having a dry film thickness of about 0.1 μm. Next, the coating composition (2) was applied in a wet film thickness of 1
Coated with a gravure coat to a thickness of 3 μm,
After drying in the drying section set at 120 mJ
/ Cm ² and cured to provide a resin layer having a dry film thickness of 5 μm. This is referred to as the cellulose ester film 20 of the present invention.

Further, the coating composition (2) was added to the coating composition (3).
The cellulose acetate propionate film coated with the coating composition (1), the coating composition (3), and the coating composition (4) was prepared in the same manner, except that the above composition was changed. This is referred to as the cellulose ester film 21 of the present invention.

The cellulose ester film 20 of the present invention
The following anti-reflection layer coating composition 1 was applied in a wet film thickness of 10 μm on the clear hard coat layer of
After irradiation with ultraviolet rays of mJ / cm ² (refractive index: 1.8
2, film thickness: 77 nm), coating composition 2 for the following antireflection layer
Was applied at a wet film thickness of 10 μm and dried at 80 ° C. for 30 minutes (refractive index: 1.45, film thickness: 90 nm) to prepare a cellulose ester film 22 of the present invention. In the same manner except that the cellulose ester film 21 of the present invention was used instead of the cellulose ester film 20 of the present invention, the following antireflection layer coating compositions 1 and 2 were applied on the antiglare layer. Inventive cellulose ester film 23
Was prepared.

<< Preparation of Antireflection Layer Coating Composition 1 >> Titanium polymer (condensation product of tetrabutoxytitanium: Nippon Soda: B-4) 125 g n-butanol 1200 g isopropyl alcohol 1200 g dipentaerythritol hexaacrylate monomer 3 g di Pentaerythritol hexaacrylate dimer 1 g Dipentaerythritol hexaacrylate trimer or higher component 1 g Dimethoxybenzophenone UV initiator 0.1 g γ-methacryloxypropyltrimethoxysilane 5 g << Preparation of antireflection layer coating composition 2 >> Tetra Ethoxysilane hydrolyzate * 180 g γ-methacryloxypropyltrimethoxysilane 5 g Cyclohexanone 3200 g * Preparation method of tetraethoxysilane hydrolyzate Ethanol was added to 250 g of tetraethoxysilane To this solution was added dropwise a hydrochloric acid aqueous solution obtained by dissolving 3 g of concentrated hydrochloric acid in 235 g of water at room temperature. After the addition, the mixture was stirred at room temperature for 3 hours to prepare.

According to the method described in Example 2, a polarizing plate and a liquid crystal display device were produced using the cellulose ester films 20, 21, 22, and 23 of the present invention as polarizing plate protective films. In producing the polarizing plate, the surface on which the coating composition (4) was applied was bonded to a polarizer. As a result, the curl of the cellulose ester film of the present invention was small, and the production of the polarizing plate was easy. Further, the absolute value of the impedance at 20 Hz exceeded 4 × 10 ⁵ Ω.
In addition, the edge portions did not peel off when the polarizing plate was cut, and the flatness was good. Furthermore, it was confirmed that the liquid crystal display device using this polarizing plate was excellent in contrast as compared with the comparative example, and was excellent as a polarizing plate for an image display device such as a liquid crystal display.

Example 6 << Preparation of Dope >> The following materials were charged in predetermined amounts into a pressurized airtight container, heated to 80 ° C., and the pressure in the container was adjusted to 2 atm. The agent was completely dissolved to obtain a dope. Next, the temperature of the dope was lowered to a casting temperature, the solution was allowed to stand overnight, and after defoaming, the solution was subjected to Azumi Filter Paper No. Prepared by filtration using 244.

(Materials) Methylene chloride 245 kg Ethanol 82 kg CAP (cellulose acetate propionate: acetyl substitution degree 2.0, propionyl group substitution degree 0.8, number average molecular weight 100,000) 100 kg Tinuvin 326 (Ciba Specialty Chemicals ( 0.7 kg Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 1.0 kg Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 1.0 kg triphenyl phosphate 10 kg ethylphthalylethyl glycolate 5 kg Aerosil R972V (Japan) Aerosil Co., Ltd.) 0.1 kg << Preparation of cellulose ester film >>
(The effective drying length of the support is 60 m), the dope temperature is adjusted to 35 ° C. and the support temperature is adjusted to 35 ° C., and the width of 1.5 m is adjusted so that the film thickness after drying on the support from the slit die becomes 40 μm. Was cast. Dry air temperature on the support is 40 ° C
And After about one round, the temperature of the support was set to 15 ° C., and the peeling tension was 160 at a film forming speed of 35 m / min from the support.
Peeled at N / m. Next, it is conveyed in a drying zone at 90 ° C. by a tenter so that the stretching ratio in the width direction becomes × 1.07 times, dried until the residual solvent amount becomes 10%, and further at 119 ° C. for 15 minutes. After drying, a cellulose ester film was prepared.

In the same manner as in Example 1, the curl value, roll smear, and tear strength were examined. As a result, the curl was 15, the roll smear was ◎, and the tear strength was 10 g. The in-plane retardation R0 is 0.2 nm, the slow axis angle is 2 °,
Rt was 40 nm. The number of bright spot foreign substances having a diameter of 0.01 mm or more was 0 / cm ² .

According to the method described in Example 2, a polarizing plate and a display device were produced using the cellulose ester film of the present invention as a protective film for a polarizing plate. As a result, the cellulose ester film of the present invention had little curl and was easy to produce a polarizing plate. There was no peeling of the edges when the polarizing plate was cut, and the flatness was good. Further, it was confirmed that the display device manufactured using this polarizing plate had excellent contrast and was excellent as a polarizing plate for an image display device such as a liquid crystal display.

[0248]

Industrial Applicability According to the present invention, a method for producing a cellulose ester film having a small amount of dirt on a peeling roll, and a cellulose ester film having a small curl and a high tear strength, a polarizing plate and a display using the same, by the production method Equipment could be provided.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of an apparatus for producing a cellulose ester laminated film of the present invention.

FIG. 2 is a sectional view of a slit die used in the manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dope liquid tank 1a Dope liquid 2 Particle addition liquid tank 2a Particle addition liquid 3 Tank 3a Ultraviolet absorber addition liquid 4a Pump 4b Pump 4c Pump 4d Pump 5a In-line mixer 5b In-line mixer 6 Slit die 7 Drum 8 Casting belt 9 Roller 10 Cellulose ester laminated film 11 Casting port 12 Slit 13 Slit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/00 C08K 5/00 C08L 1/10 C08L 1/10 G02B 5/30 G02B 5/30 // B29K 1:00 B29K 1:00 B29L 7:00 B29L 7:00 F term (reference) 2H049 BA02 BB13 BB33 BB65 BC09 BC14 4F071 AA09 AE05 AF16 AH12 BB02 BC12 4F205 AA01 AB07 AB11 AB14 AC05 AG01 AH73 AR04 AR08 GA07 GB02 GC07 GE22 GN24 GN29 4J002 AB021 BD122 BG032 CP032 DE097 DE147 DE237 DJ007 DJ017 DJ037 DJ047 EJ066 EU176 FD056 HA05

Claims (15)

[Claims] 1. A compound having an acyl group having 2 to 4 carbon atoms as a substituent, wherein the degree of substitution of an acetyl group is represented by X and the degree of substitution of a propionyl group or a butyryl group is represented by Y,
A method for producing a cellulose ester film by a solution casting method using a dope containing at least one cellulose ester containing a cellulose ester which simultaneously satisfies a) and (II) and an organic solvent, wherein the dope is 2
Having a solid concentration of 1% by mass or more, casting the dope on a support, forming a web (dope film), and peeling the web (dope film) from the support. A method for producing a cellulose ester film. (Ia) 2.3 ≦ X + Y ≦ 3.0 (II) 0 ≦ X ≦ 2.5 2. The method for producing a cellulose ester film according to claim 1, wherein the formula (Ia) is represented by the following formula (Ib). (Ib) 2.6 ≦ X +
Y ≦ 3.0 3. The method for producing a cellulose ester film according to claim 1, wherein the organic solvent contains methylene chloride. 4. The dope comprises a plasticizer A having a melting point of 25 ° C. or more and a plasticizer B having a melting point of less than 25 ° C. in a total amount of 1 to 20.
The method for producing a cellulose ester film according to any one of claims 1 to 3, wherein the cellulose ester film is contained by mass%. 5. The method for producing a cellulose ester film according to claim 1, wherein the dope contains an ultraviolet absorbent having a melting point of 20 ° C. or less. 6. The method for producing a cellulose ester film according to claim 1, wherein the dope contains fine particles. 7. 20 Hz of a cellulose ester film
The method for producing a cellulose ester film according to any one of claims 1 to 6, wherein the absolute value of the impedance in the above is 4 x 10 < ⁵ > [Omega] or more. 8. After the web (doped film) is peeled off from the support, the residual solvent amount of the web (doped film) is reduced to 35% by mass or less, and the residual solvent amount is reduced to 10% by mass or less while applying a tenter. The method for producing a cellulose ester film according to any one of claims 1 to 7, further comprising a step of drying until the cellulose ester film becomes. 9. The method for producing a cellulose ester film according to claim 1, wherein a web (doped film) is formed on the support at a transport speed of 30 to 150 m / min. 10. The cellulose ester film having a dry thickness of 20 to 65 μm.
10. The method for producing a cellulose ester film according to any one of items 9 to 9. 11. The method according to claim 1, wherein when the web (dope film) is peeled from the support, the web is peeled at a peeling tension of 190 N / m or less, and further dried at a transporting tension of 190 N / m or less. The method for producing a cellulose ester film according to any one of the preceding claims. 12. The method for producing a cellulose ester film according to claim 1, wherein Y is a degree of substitution of a propionyl group. 13. A cellulose ester film produced by the production method according to claim 1. Description: 14. A polarizing plate comprising the cellulose ester film according to claim 13. 15. A display device comprising the polarizing plate according to claim 14.