JP2002086474A - Cellulose ester film, method and apparatus for manufacturing the same and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clean cellulose ester film by making a plasticizer or ultraviolet absorber, which is easy to precipitate, evaporate or volatilize from a web after peeling, hard to adhere to the roll provided between a peeling process and a drying apparatus, a method and apparatus for manufacturing the same and a polarizing plate. SOLUTION: In the method for manufacturing the cellulose ester film with a thickness of 20-80 μm using a solution casting film forming apparatus, the web, of which the residual solvent amount after peeling is 10-150 mass %, is fed while brought into contact with the roll of which the surface roughness Ry is 0.6 μm or less and the surface energy at 20 deg.C is 70-100 mN/m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulose ester film having a thickness of 20 to 80 .mu.m, a method for producing a cellulose ester film, an apparatus for producing a cellulose ester film, and a polarizing plate useful for a liquid crystal image display device.

[0002]

2. Description of the Related Art Conventionally, a cellulose ester film used as a film base of a silver halide photographic light-sensitive material is manufactured by using a usual solution casting method and apparatus. A conventional method for producing a cellulose triacetate film by a solution casting film forming method is performed by a cellulose triacetate film production apparatus as shown in FIG. FIG. 1 is a schematic diagram of a solution casting film-forming cellulose ester film manufacturing apparatus. First, a cellulose ester is dissolved in a mixed solvent of a good solvent that dissolves it and a poor solvent that does not dissolve it, and a plasticizer or an ultraviolet absorber is added thereto to prepare a cellulose triacetate solution (hereinafter also referred to as a dope). An infinitely moving endless metal support (for example, a belt or a drum) 3 having a mirror-finished surface is cast from the die 2 onto a metal support 3 (hereinafter sometimes referred to as a metal support or simply a support), and a doped film (web) is formed. 1) is peeled off by a peeling roll 4, transported by a roll 11, introduced into a roll drying device 5, and the web 1 is drawn around by a roll group 6, during which the web 1 is dried by the introduced dry gas air 7. The cellulose triacetate film is wound and manufactured by a winder 8 as a cellulose triacetate film. In general, drying is generally performed by passing the web through a number of transport rolls in a zigzag manner as shown in FIG. 1 and applying a drying air thereto. However, as shown in US Pat. No. 2,319,053, infrared rays are used. There is also a method of drying such as. Rather than directly hanging the web on a roll, a system has been developed in which air is blown out and the web is floated by the pressure to move the web in a non-contact state with the hanging body (for example, Japanese Patent Application Laid-Open No. 55-135046).
Issue publication). On the other hand, as a stretching method performed to improve the mechanical strength of a film such as polyester or polypropylene, there is a tenter method in which both side edges of the film are fixed with clips or the like and stretched 2 to 6 times. A technology for manufacturing a substrate of a liquid crystal display panel from a film of a phenoxy resin or the like utilizing this tenter method has also been developed (Japanese Patent Application Laid-Open No. 59-211006), and a cellulose acetate film can be used for this film. There is suggested therein a method for producing a cellulose triacetate film by a tenter drying apparatus as disclosed in JP-A-4-284221 and JP-A-62-115035. FIG. 2 is a schematic diagram of a solution casting film-forming cellulose ester film manufacturing apparatus having a tenter drying apparatus. The web 1 peeled off by the peeling roll 4 is introduced into a tenter dryer 9 and dried by holding both ends of the web with clips to maintain the width or slightly stretching the width. After the drying is completed, a wound cellulose ester film is obtained.

A liquid crystal display (LCD) has a low voltage,
Since it can be directly connected to an IC circuit with low power consumption and can be made thin, it is widely used as a display device of a word processor, a personal computer, or the like. By the way, the basic configuration of this liquid crystal image display device is such that, for example, a polarizing plate is provided on both sides of a liquid crystal cell, and this polarizing plate transmits only light having a polarization plane in a certain direction. Therefore, the liquid crystal display device plays an important role in visualizing a change in the orientation of the liquid crystal display device due to an electric field. That is, the performance of the liquid crystal display device largely depends on the performance of the polarizing plate.

The cellulose ester film used for this polarizing plate is alkali-saponified on its surface and is uniaxially stretched and is coated with iodine-dyeed polyvinyl alcohol film on one or both sides of a polarizing film as a protective film for the polarizing plate. Then, a laminated polarizing plate is produced via an adhesive such as polyvinyl alcohol. In particular, since thinning and miniaturization are possible, application to notebook personal computers, car navigators, mobile phones, game machines, and the like progresses very quickly, and further thinning and miniaturization have been achieved. It is going. Accordingly, a conventionally used cellulose ester film of a liquid crystal image display device requires a thinner film. However, in the conventional method for producing a film-based cellulose ester film of a silver halide photographic light-sensitive material, there are many problems in producing a thin cellulose ester film as a protective film for a polarizing plate. It was difficult to obtain an ester film.
If the production conditions of the thin and thick cellulose ester films were made the same, various troubles occurred, and it became necessary to review the production conditions and production equipment.

For example, in the production of a film base of an ordinary silver halide photographic light-sensitive material, some stains are caused by a plasticizer or the like. However, when a thin cellulose ester film of a protective film for a polarizing plate is produced, more stains are produced. It will be easier. The plasticizer or ultraviolet absorber in the web precipitates, evaporates or volatilizes in the transporting process by rolls from immediately after the peeling in the first half of the drying process to the introduction into the drying device and the transporting process after being introduced into the drying device. And adheres to the roll to contaminate the web, or condenses on the wall of the drying device to form droplets and contaminate the web.

[0006] The soiling of the web as described above becomes a defect of the cellulose ester film and is subject to deletion, resulting in a problem of economic loss such as a decrease in product yield and a resulting decrease in productivity. As shown in FIG. 2, after peeling the web, there is a method in which both ends of the web are immediately gripped and introduced into a tenter that holds or stretches in the width direction. However, both ends of the web are easily curled and broken. Each time the film is cut in the tenter and production is often interrupted, and transported by rolls before introduction into the dryer.

Further, a plasticizer or an ultraviolet absorber easily precipitates from the web immediately after peeling, and the roll is soiled, so that it is transferred to the web again, and the stain is enlarged. Various attempts have been made to address this problem. For example, JP-A-8
-25459, 8-57879, 4-8501
No. 1, 5-185443 or 5-18544
In Japanese Patent Publication No. 5 (1993), a roll is formed into a hollow cylinder, the side surface of the roll is sealed with a side plate, a refrigerant is filled therein, and the roll is provided with a groove over the entire width in the rotation direction to reduce the adhesion of dirt to the roll. A method in which a web having a residual solvent amount of less than 5% by mass after peeling is brought into contact with a roll heated to 100 to 160 ° C. to change the distribution of a plasticizer near the surface of the web, thereby reducing stains. A method of reducing contamination by transporting the web at 20 ° C. or less to a roll having a surface energy of 800 μN / cm or less.
A method for reducing contamination by setting the surface temperature up to 30 mm inward from both ends of the roll to 20 ° C. or less, or when the residual solvent amount after peeling is 68% by mass or more, the transfer time is at least 20 seconds from the peeling point. During, the drying air temperature is 30-80
And the like. As a method of removing dirt in fields other than cellulose ester film, a falling-off matting agent that comes out of the manufacturing process of aluminum lithographic printing plates adheres to the surface of the plate, which has a large effect on quality, so it can be applied to the surface of the roll during the process. This is a method in which a roll with an adhesive tape is brought into contact with the roll to take it out (Japanese Patent Laid-Open No. 11-11762).

[0008]

However, these methods cannot suppress the precipitation of the plasticizer and the like, so that some dirt remains, and not only the quality and yield of the film are reduced, but also the machine is stopped and the roll is stopped. In many cases, productivity is reduced by removing dirt such as dirt, or by operating the machine to remove dirt without stopping the machine.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to provide a plasticizer or an ultraviolet absorber which easily precipitates, evaporates or volatilizes from a web after peeling. Provided are a method for manufacturing a cellulose ester film and an apparatus for manufacturing a cellulose ester film, which are hardly adhered to a roll before the drying apparatus is introduced.

[0010]

The present invention comprises the following constitutions.

(1) In a method for producing a cellulose ester film having a film thickness of 20 to 80 μm by using a solution casting film forming apparatus, a web having a residual solvent amount of 10 to 150% by mass after peeling is treated with a surface roughness Ry is 0.6 μm or less, and the surface energy at 20 ° C. is 70 to 100 mN / m.
A method for producing a cellulose ester film, wherein the film is conveyed while being in contact with a roll.

(2) The method for producing a cellulose ester film according to (1), wherein the first one of the rolls is a release roll.

(3) The cellulose ester according to (1) or (2), wherein the roll is only a roll that contacts the air-side surface of the web on the endless metal support that moves infinitely. Film production method.

(4) The roll according to any one of (1) to (3), wherein the roll is hard chrome-plated.
Item 13. The method for producing a cellulose ester film according to item 4.

(5) Roll diameter is 85 to 300 mm
The method for producing a cellulose ester film according to any one of (1) to (4), wherein

(6) A solution casting film forming apparatus having a roll and a roll surface cleaning means, wherein the cleaning means moves in the axial direction of the roll while adhering an organic solvent to the roll, and a means for adhering the organic solvent to the roll. An apparatus for producing a cellulose ester film, comprising means for wiping a roll surface.

(7) The apparatus for producing a cellulose ester film according to (6), wherein the means for attaching the organic solvent to the roll is a means for supplying the organic solvent by capillary action.

(8) The apparatus for producing a cellulose ester film according to (6) or (7), wherein the wiping means has a nonwoven fabric.

(9) The apparatus for producing a cellulose ester film according to any one of (6) to (8), wherein the means for attaching the organic solvent includes a nonwoven fabric containing the organic solvent.

(10) Cellulose characterized in that the web is conveyed while being in contact with a roll that has been wiped and cleaned by applying the organic solvent by the means according to any one of (6) to (9). A method for producing an ester film.

(11) The organic solvent is a good solvent having a solubility in cellulose ester, or the organic solvent is a mixture of a good solvent having a solubility in cellulose ester and a poor solvent having no solubility. (10) The method for producing a cellulose ester film according to (10).

(12) A cellulose ester film produced by the method according to (10) or (11).

(13) A polarizing plate using the cellulose ester film of (12). The present invention will be described in detail.

First, the composition constituting the cellulose ester film according to the present invention will be described.

The cellulose ester used in the cellulose ester film according to the present invention is cellulose selected from linter pulp, wood pulp and kenaf pulp, and reacted with acetic anhydride, propionic anhydride or butyric anhydride in a conventional manner. The degree of substitution of all acyl groups with respect to hydroxyl groups of cellulose is 2.5 to 3.
Cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate of 0 are preferably used. The cellulose ester according to the present invention preferably has an acetyl group substitution degree of at least 1.5 or more. The degree of substitution of the acyl group of the cellulose ester can be measured according to ASTM D-817-91. The molecular weight of these cellulose esters is 70,000 to 30 as a number average molecular weight.
The range of 0000 is preferable because the mechanical strength when formed into a film is strong. 80,000-200,00
0 is preferred. Usually, the cellulose ester is formed into flakes after treatment such as washing with water after the reaction, and is used in that shape. The particle size is 0.05 to 2.0 mm.
It is preferred that the content be within the range, since the solubility can be accelerated.

The cellulose ester film contains a plasticizer such as a phthalate ester or a phosphate ester, an ultraviolet absorber, an antioxidant, a matting agent, etc.
The performance of a silver halide photographic light-sensitive material and a liquid crystal image display device resulting from a cellulose ester film can be improved.

In the present invention, a plasticizer is preferably contained in the cellulose ester film. The plasticizer that can be used is not particularly limited, and examples of the phosphate ester type include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like. As phthalic acid esters,
Examples of glycolic acid esters such as diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, and di-2-ethylhexyl phthalate include triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, and methyl. Phthalylethyl glycolate, butylphthalylbutyl glycolate and the like can be mentioned. If necessary, two or more plasticizers may be used in combination. When used for a cellulose ester, the proportion of a phosphate ester-based plasticizer is 50% by mass.
The following are preferable because they hardly cause hydrolysis of the cellulose ester film and are excellent in durability. It is more preferable that the ratio of the phosphate plasticizer is smaller, and it is particularly preferable to use only the phthalate or glycolate plasticizer. The amount of the plasticizer added to the cellulose ester is 0.5 to 30% by mass.
Is preferred, and particularly preferably 2 to 15% by mass.

Further, in the present invention, it is preferable that an ultraviolet absorber is contained in the cellulose ester film. The ultraviolet absorber is excellent in absorbing the ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal, and is excellent. From the viewpoint of good liquid crystal display properties, those having absorption of visible light having a wavelength of 400 nm or more as little as possible are preferably used. In particular, the transmittance at a wavelength of 370 nm needs to be 10% or less, preferably 5% or less, and more preferably 2% or less. In the present invention, as an ultraviolet absorber that can be used, for example, oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds,
Nickel complex salt compounds and the like can be mentioned, but benzotriazole compounds having little coloring are preferable. Examples of commercially available benzotriazole-based UV absorbers include Tinuvin 109, Tinuvin 171, Tinuvin 326, and Tinuvin 3 manufactured by Ciba Specialty Chemicals, Inc.
27, Tinuvin 328 and the like can be preferably used, but are not limited thereto. Two or more ultraviolet absorbers may be used. The method of adding the UV absorber to the dope
The ultraviolet absorber may be added after being dissolved in an organic solvent such as alcohol, methylene chloride, methyl acetate, or dioxolane, or may be added directly to the dope composition.
Those which do not dissolve in an organic solvent such as inorganic powders are dispersed in an organic solvent and a cellulose ester using a dissolver or a sand mill and then added to the dope. In the present invention, the amount of the ultraviolet absorber used can be added in the range of 0.5 to 20% by mass based on the cellulose ester,
It is preferably 0.6 to 5.0% by mass, particularly preferably 0.1% by mass.
6 to 2.0% by mass.

Further, the cellulose ester film of the present invention preferably contains an antioxidant. As the antioxidant, a hindered phenol compound is preferably used, and 2,6-di-t- Butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3
-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, 1,3,5-trimethyl-
2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-
(t-butyl-4-hydroxybenzyl) -isocyanurate and the like. Particularly, 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, N, N'-bis [3- (3,5-di-t-butyl-
Hydrazine-based metal deactivators such as 4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-
A phosphorus-based processing stabilizer such as (t-butylphenyl) phosphite may be used in combination. The addition amount of these compounds is 1 ppm to 1.0% by mass relative to the cellulose ester.
% Is preferable, and 10 to 1000 ppm is more preferable.

In the present invention, the cellulose ester film preferably contains a fine particle matting agent. Examples of the fine particle matting agent include silicon dioxide,
Titanium dioxide, aluminum oxide, zirconium oxide,
It is preferable to contain inorganic fine particles such as calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate, and crosslinked polymer fine particles. Among them, silicon dioxide is preferable because the haze of the film can be reduced. The average secondary particle size of the fine particles is 0.01-1.
In the range of 0 μm, the content is preferably 0.005 to 0.3% by mass relative to the cellulose ester. Fine particles such as silicon dioxide are often surface-treated with an organic substance, but such particles are preferable because the haze of the film can be reduced. Preferred organic substances in the surface treatment include halosilanes, alkoxysilanes, silazane,
Siloxane and the like. The larger the average particle size of the fine particles, the greater the matting effect, and the smaller the average particle size, the better the transparency. Therefore, the average primary particle size of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 14 nm.
It is. These fine particles are usually present as an aggregate in the cellulose ester film, and it is preferable to form irregularities of 0.01 to 1.0 μm on the surface of the cellulose ester film. As fine particles of silicon dioxide, AEROSIL 200, 200V manufactured by Aerosil Co., Ltd.,
300, R972, R972V, R974, R202,
R812, OX50, TT600, etc., preferably AEROSIL200V, R972, R
972V, R974, R202, and R812. Two or more of these matting agents may be used in combination. When two or more kinds are used in combination, they can be used by mixing at an arbitrary ratio. In this case, matting agents having different average particle diameters and materials, for example, AEROSIL 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9 to 0.1.

The cellulose ester film may contain a dye or the like. For silver halide photographic materials, a colorant for preventing light piping is added. The addition amount of these compounds is preferably 1 ppm to 1.0% by mass relative to the cellulose ester, and 10 to 1000 p
pm is more preferred. In addition, an antistatic agent, a flame retardant, a lubricant, an oil agent, and the like may be added.

These additives 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.

Next, a method for preparing a cellulose ester dope in the present invention will be described. The flake-like cellulose ester is dissolved in an organic solvent, mainly a good solvent for the cellulose ester, with stirring in a dissolving vessel to form a dope. The dissolution is carried out at normal pressure, below the boiling point of the main solvent, under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 or JP-A-9-95538. There are various dissolving methods such as a method performed by a cooling dissolution method as described in JP-A No. 11-21379 and a method performed at a high pressure as described in JP-A-11-21379. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next step by a pump. The concentration of the cellulose ester in the dope is about 10 to 35% by mass. More preferably, it is 15 to 25% by mass. In order to incorporate a polymer useful in the present invention into the cellulose ester dope, the polymer may be dissolved in an organic solvent in advance and then added or directly added to the cellulose ester dope. In this case, the polymer is added so that the polymer does not become cloudy or phase-separated in the dope. The amount of addition is as described above.

Organic solvents as good solvents for cellulose esters include methyl acetate, ethyl acetate, amyl acetate, ethyl formate, acetone, cyclohexanone, methyl acetoacetate, tetrahydrofuran, 1,3-dioxolan, and 4-methyl-1,3. -Dioxolan, 1,4-dioxane, 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, 2-pyrrolidone, N-
Examples thereof include methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, methylene chloride, and bromopropane. Of these, methyl acetate, acetone, and methylene chloride are preferably used. However, due to recent environmental problems, non-chlorine organic solvents tend to be more preferable. It is preferable to use a lower alcohol such as methanol, ethanol, or butanol in combination with these organic solvents, because the solubility of the cellulose ester in the organic solvent can be improved and the viscosity of the dope can be reduced. Particularly, ethanol having a low boiling point and low toxicity is preferable. The organic solvent used in the dope according to the present invention is preferably used by mixing a good solvent and a poor solvent for the cellulose ester from the viewpoint of production efficiency, and a preferable range of the mixing ratio between the good solvent and the poor solvent is good. Solvent 70-98
% By mass, and the content of the poor solvent is 2 to 30% by mass. The good solvent and the poor solvent used in the present invention are defined as those that dissolve the cellulose ester used alone, and those that do not dissolve alone are poor solvents. Although the poor solvent used for the dope according to the present invention is not particularly limited, for example, methanol, ethanol, n-butanol, cyclohexane, acetone, cyclohexanone and the like can be preferably used. For the polymer useful in the present invention, the organic solvent is preferably selected using a good solvent for the cellulose ester. As described above, when a low-molecular plasticizer is used, it can be performed by a normal addition method, even if it is directly added to the dope, or it is dissolved in an organic solvent and then poured into the dope. Good.

In the present invention, when the various additive solutions or dispersions as described above are added to the cellulose ester dope, they are respectively transferred and merged when the transfer tubes merge, and immediately thereafter, the mixture is mixed with the in-tube mixer. A method of thoroughly mixing is also preferable. For example, it is preferable to use an in-line mixer such as a static mixer SWJ (Toray static type in-tube mixer Hi-Mixer) (manufactured by Toray Engineering). When an in-line mixer is used, the present invention can be applied to a dope in which cellulose ester is concentrated and dissolved under high pressure.

In the present invention, it is necessary to remove foreign substances, particularly foreign substances which may be recognized as an image in a liquid crystal display, by filtering the cellulose ester dope. It can be said that the quality of the protective film for a polarizing plate is determined by this filtration. It is preferable that the filtration material used for filtration has a small absolute filtration accuracy, but if the absolute filtration accuracy is too small, clogging of the filtration material is likely to occur, and the filtration material must be replaced frequently, which reduces productivity. There is a problem. For this reason, the filter medium used for the cellulose ester dope of the present invention preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and more preferably 0.003 to 0.006 mm. Filter media are more preferred. There is no particular limitation on the material of the filter medium, and a normal filter medium can be used. However, a filter medium made of a plastic fiber such as polypropylene or Teflon or a metal filter medium such as a stainless steel fiber is preferable because the fibers do not fall off. Filtration of the cellulose ester dope of the present invention can be performed by a usual method, but a method of filtering while heating under pressure at a temperature not lower than the boiling point of the solvent at normal pressure and in a range in which the solvent does not boil, before and after the filtration material Of the pressure difference (hereinafter sometimes referred to as filtration pressure) is small, which is preferable. A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C.
The smaller the filtration pressure, the better. Filtration pressure is 1.6 × 10 ⁶ Pa
It is preferably at most 1.2 × 10 ⁶ Pa, more preferably at most 1.0 × 10 ⁶ Pa. When the raw material cellulose contains a cellulose ester having an unsubstituted or low-substituted acyl group, foreign matter failure (hereinafter sometimes referred to as a luminescent spot) may occur. The bright spot is 2 in the orthogonal state (cross Nicol)
Put the cellulose ester film between the two polarizing plates,
Light is irradiated from one side, and the optical microscope (5
Observation at 0x), if it is a normal cellulose ester film, the light is blocked and nothing looks black, but if there is a foreign substance, the light leaks out of it and looks like a spot-like glow. . The greater the diameter of the luminescent spot, the greater the harm in the case of a liquid crystal image display device, preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. The diameter of a bright point means a diameter measured by approximating the bright point to a perfect circle. Bright spot is not intended practical problem as long as 400 / cm ² or less of the diameter is preferably 300 / cm ² or less, 200 cells /
cm ² or less is more preferable. In order to reduce the number and size of such bright spots, it is necessary to sufficiently filter fine foreign matter. In addition, as described in JP-A-2000-137115, a method in which a pulverized product of a once-formed cellulose ester film is re-added to a dope at a certain ratio and used as a raw material for a cellulose ester and its additive has a bright spot. Since it can be reduced, it can be preferably used.

Next, in the process of producing the cellulose ester film, the step of casting the dope on the metal support, the step of drying on the metal support, the step of separating the web from the metal support, and the step of The drying step will be described.

The surface of the endless metal support for infinite transfer is a mirror surface. In the casting step, the dope is fed to a pressurizing die through a pressurized metering gear pump, and at a casting position,
This is a step of casting a dope from a pressure die onto a metal support (for example, a stainless steel belt or a rotating metal drum). Other casting methods include a doctor blade method in which the thickness of the cast dope film is adjusted with a blade or a reverse roll coater method in which the dope film is adjusted with a counter-rotating roll, but the slit shape of the die is adjusted. A pressure die that can be formed and has a uniform thickness is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided to form a plurality of layers. In order to adjust the film thickness, it is preferable to control the dope concentration, the amount of liquid sent from the pump, the slit gap of the die cap, the extrusion pressure of the die, the speed of the metal support, and the like so as to obtain a desired thickness.

The drying step on the metal support is a step of heating the web (the web is referred to as a dope film after casting on the metal support) on the support to evaporate the solvent. To evaporate the solvent, there are a method in which heated air is blown from the web side and the back side of the support, a method in which heat is transferred from the back side of the support by a heating liquid, and a method in which heat is transferred from the front and back sides by radiant heat. A method of combining them is also preferable. In addition, if the thickness of the web is thin, drying is quick. The temperature of the metal support may be the same as a whole or different depending on the position.

The peeling step is a step of evaporating the organic solvent on the metal support and peeling the web before the metal support makes one round, and then the web is sent to a drying step. The position at which the web is peeled off from the metal support is referred to as a peeling point, and the roll which assists peeling is referred to as a peeling roll. Although it depends on the thickness of the web, if the residual solvent amount of the web at the peeling point (the following formula) is too large, it is difficult to peel off. Conversely, if the web is sufficiently dried on the support and then peeled off, the web May be peeled off. 10 residual solvent
At ~ 150% by mass, the web is peeled off. As a method of increasing the film forming speed (the film forming speed can be increased because the amount of the residual solvent is increased as much as possible), there is a gel casting method capable of separating even if the amount of the residual solvent is large. Examples of the method include a method in which a poor solvent for the cellulose ester is added to the dope, gelling is performed after casting the dope, and a method in which the temperature of the support is lowered to gelate. There is also a method of adding a metal salt to the dope.
By gelling on the support to strengthen the film, peeling can be accelerated and the film forming speed can be increased. If the residual solvent is peeled off at a higher point, if the web is too soft, the flatness at the time of peeling will be impaired, or shear and vertical streaks will easily occur due to peel tension, and the amount of residual solvent will be determined based on the balance between economic speed and quality. Can be

The amount of the residual solvent used in the present invention can be represented by the following formula. Residual solvent amount (% by mass) = {(M−N) / N} × 100 Here, M is the mass of the web at any time, and N is the mass of the M when dried at 110 ° C. for 3 hours. is there.

The present invention can be broadly divided into two types, one relating to a roll for transporting the web after peeling and the other relating to a cleaning device for cleaning dirt attached to the roll.

In the constitutions (1) to (5) of the present invention, the web having a residual peeling solvent amount of 10 to 150% by mass has a surface roughness Ry of 0.6 μm or less after peeling and before introduction into a drying apparatus. And transported by a roll having a surface energy at 20 ° C. of 70 to 100 mN / m.

The surface roughness Ry referred to in the present invention is JIS standard
It refers to “maximum height Ry” defined by B0601. Normally, it is considered that it is less likely that the web is brought into contact with the roll having a matte surface, and the web is conveyed. However, as a result of examination, the roll having a mirror surface has a surface roughness Ry of 0.6 μm or less and is completely smooth. It has been found that dirt can be prevented with a simple mirror roll. The surface roughness Ry is preferably 0.4 μm or less, more preferably 0.2 μm or less. That is, the smoother the surface, the better. In other words, the mirror surface is better.

Also suitable for the present invention are hard chromium plated rolls. Incidentally, the surface energy of the stainless steel roll at 20 ° C. is 100 mN / m or more, and that of the Teflon (registered trademark) roll is 18 to 2 μm.
5 mN / m. Japanese Unexamined Patent Publication (Kokai) No. 4-85011 discloses a method in which a dope is cast on a metal support cooled to 20 ° C. or less, and a web solidified by cooling is peeled with a very high residual solvent amount. And that the surface energy at 20 ° C. is 20 to 25 mN / m. According to the study by the present inventor, it was found that although there was certainly no adhesion stain, the scratches were easily made, and the scratches caused unevenness on the web and became another defect.
Therefore, surface energy and appropriate hardness are required, and in the present invention, hard chromium-plated rolls are preferable and suitable. The method for measuring the surface energy is based on the contact angle between water and methylene iodide.
It can be calculated using the Fowkes-Owens equation.

Since the web immediately after peeling has a strong precipitation of additives such as a plasticizer and is easily stained from the roll after peeling, the roll immediately after peeling, that is, the peeling roll, particularly, has a surface roughness Ry of 0.6 μm or less. It is important to use a roll having a surface energy of 70 to 100 mN / m at 20 ° C., particularly a hard chrome-plated roll. It is preferable that a large number of such rolls are used as such rolls after the first roll is introduced into the drying apparatus.

Further, after the web is peeled off, the surface of the air-side web (hereinafter referred to as “the web side”) while the web is being dried on the metal support.
This surface is sometimes referred to as surface A), and the precipitation of the plasticizer and the like occurs more intensely than the surface on the metal support side (hereinafter, this surface may be referred to as surface B). The surface has a surface roughness Ry of 0.6 μm or less and a surface energy at 20 ° C. of 70 to 100 mN / m.
Is particularly good for eliminating or reducing additive deposition fouling.

When a web having a small thickness (less than 85 mm) and having a relatively small amount of residual solvent, as in the present invention, is conveyed by a roll after peeling, the roll has a small diameter (less than 85 mm). Deformed by the force of pressing,
Additives that are easy to stretch, but also precipitate, evaporate or volatilize from the web, adhere to the rolls, fouling the web and easily forming a push. In addition, when the roll is thick (diameter exceeding 300 mm), the roll may not be rotated well with a weak tension, and the web may be scratched. Therefore, in order to rotate this thick roll in synchronization with the movement of the web, it is necessary to increase the tension, and as a result, as described above, there is a problem of dirt and pushing. Therefore, the diameter of the roll used in the present invention is 85 to 85.
300 mm is preferred, and 100-200 mm is more preferred. Pressure P on the roll in the radial direction (N / mm)
Is represented as P = T / R · L. Here, T (N /
mm) is the web tension, R is the radius of the roll (mm), L
(Mm) is the width of the web.

The following constitutions (6) to (11) of the present invention comprise means for adhering an organic solvent capable of moving in the roll axis direction to the roll between the peeling roll and the inlet of the tenter dryer. The present invention relates to an apparatus for casting a solution of a cellulose ester film having means for cleaning the organic solvent by wiping, and a method for producing a cellulose ester film. One or more rolls are provided between the release roll and the inlet of the tenter dryer, and any of the rolls may be provided with a cleaning unit. Of the cleaning means,
The means for adhering the organic solvent to the roll surface can be used without limitation as long as it can supply and adhere the organic solvent. However, a means for sucking up the organic solvent by capillary action and supplying the organic solvent to the roll surface is preferable. As described above, the exfoliated web tends to adhere to the roll surface due to precipitation, evaporation or volatilization of an additive such as a plasticizer, particularly from the side A, and the roll contacting the side A is provided with a cleaning means. Is good. In some cases, the peeling roll that the surface A contacts first may be stained, and the peeling roll may be provided with a cleaning unit. Either way, it is effective to attach to the roll that is most easily soiled. In particular, it is preferable to install on a roll in contact with the A side.

The material used for the cleaning means according to the present invention, which sucks up the organic solvent by capillary action, has a porous or fibrous structure. Pads and cloths (sheets) made of non-woven fabric are preferred examples. As the material of the nonwoven fabric, cellulosic,
Polyurethanes, polyesters, acrylics and the like are preferred. As a commercially available nonwoven fabric, Bencott manufactured by Ozu Sangyo can be preferably used. As an organic solvent used for cleaning, an organic solvent used for dope is preferable, and methylene chloride and methyl acetate are particularly preferable. It is also preferable to use methanol or ethanol, which is a poor solvent for the cellulose ester, in a mixture with the above solvent. Particularly, ethanol is preferable. Acetone is also preferably used.

The material used for the wiping means is preferably a pad which does not generate dust or swarf during wiping, as described above. For example, a pad made of non-woven fabric is preferable.

The cleaning means of the apparatus for producing a cellulose ester film of the present invention comprises a pair of a means for adhering an organic solvent to a roll and a means for wiping adjacent to the roll. It can move in the direction of rotation. That is, the organic solvent adheres to the roll shortly after the web leaves the roll, and is subsequently wiped. The attached organic solvent dissolves the dirt and wipes it before it dries. It is good to both apply the organic solvent to the roll and wipe the entire width of the web at once, but this requires a large-scale apparatus and deteriorates workability. Therefore, the above movable type is better. There may be any number of rolls to be cleaned, and the number of rolls may be increased or decreased depending on manufacturing conditions or how dirt is generated.

FIG. 3 is a perspective view of the movable cleaning means and the roll as viewed from the direction. Dirt precipitated from the web 1 being conveyed by the roll 11 is cleaned by a cleaning unit 20 that moves in the roll axis direction. Reference numeral 25 denotes a base having rails for movable cleaning means.

FIG. 4 is a perspective view of the cleaning means viewed from the roll axis direction, and is an example of the cleaning means 20. It has an organic solvent attaching pad 21 for attaching an organic solvent to a roll and a wiping pad 23. Reference numeral 22 denotes an organic solvent reservoir for supplying an organic solvent to the organic solvent attaching pad 21. An organic solvent is supplied to the organic solvent reservoir 22 from an organic solvent supply source (not shown). The organic solvent attaching pad 21 sucks up the organic solvent from the organic solvent reservoir 22 by capillary action, and attaches the organic solvent to the roll. Reference numeral 24 denotes a movable platform for moving these pads in the roll axis direction. The movable platform is moved on a platform 25 having rails by a power transmission device (not shown). The roll 11 to which the organic solvent has adhered is then wiped off with a wiping pad 23.

FIG. 5 is a perspective view of the cleaning means viewed from the roll axis direction, which is another example of the cleaning means 20. As shown in FIG. The movable table 24 and the table 25 having rails as shown in FIG. 4 on which the cleaning means of FIG. 5 is mounted are omitted. The mechanism for attaching the organic solvent is different from that shown in FIG. 4 in that the organic solvent is attached to the roll using a continuous cloth-like nonwoven fabric instead of a pad. The non-woven fabric 26 for attaching an organic solvent is unwound from the non-woven fabric main roll 30,
The organic solvent is supplied from the back side by the organic solvent supply roll 27, attached to the roll 11, and taken up by the nonwoven fabric take-up 31. The organic solvent supply roll 27 is made of a material such as a non-woven fabric. The organic solvent supply roll 27 receives the supply of the organic solvent from the organic solvent supply source 28, is sucked up by the organic solvent attaching non-woven fabric 26 by capillary action, and adheres to the roll 11. ing. The roll to which the organic solvent has adhered is immediately wiped off with the nonwoven fabric 29 for wiping. Non-woven cloth 29 for wiping is non-woven cloth
After being fed from 0 and wiping off dirt, it is wound up by the nonwoven fabric take-up 31.

FIGS. 3 to 5 show only a part of the present invention and are not limited to them. Configuration of the present invention (1)
2) is a cellulose ester film produced by the above production method, and the constitution (13) is a polarizing plate using this cellulose ester film. The cellulose ester film produced by the cellulose ester film producing apparatus having the above-mentioned cleaning means has no stain and is useful as a protective film for a polarizing plate.

The cellulose ester film of the present invention is excellent in optical isotropy and free from stains, and is used for a liquid crystal display member. The liquid crystal display member is a member used for a liquid crystal display device. For example, a polarizing plate, a protective film for a polarizing plate, a retardation plate, a reflector, an optical compensation film, a viewing angle improving film, an antiglare film, Reflective films, antistatic films and the like can be mentioned. Among the above descriptions, it is preferably used for a polarizing plate or a protective film for a polarizing plate.

The polarizing plate of the present invention can be manufactured by a conventionally known method. As an example, the cellulose ester film is subjected to a surface saponification treatment with a 2.5 mol / l sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, washed with water for 3 minutes, and dried to obtain a surface-saponified protective film for a polarizing plate. Separately, an aqueous solution containing polyvinyl alcohol having a thickness of 120 μm and containing 1 part by mass of iodine and 4 parts by mass of boric acid.
It is immersed in a mass part and stretched 4 times in the longitudinal direction at 50 ° C. to obtain a polarizer. A polarizing plate can be produced by laminating the surface-saponified cellulose ester film on one or both sides of this polarizer with a 5% by mass aqueous solution of completely saponified polyvinyl alcohol as an adhesive.

[0059]

The present invention is illustrated by the following examples, but is not limited thereto.

[Evaluation method] (Observation and evaluation of pushed / foreign matter / dirt) A cut was cut out from the cellulose ester film to a length of 1 m in the full width direction in the longitudinal direction. The presence or absence and size of stains were observed and evaluated according to the following grades.

AA: Almost no push, no foreign matter, and dirt A: 0 to 10 pushes, foreign matters, and dirt with a size of 50 μm or more and less than 50 μm were observed B: Size of 50 μm or more No pushing, foreign matter, and dirt were observed, and 11 to 30 pieces with a size of less than 50 μm were observed. C: 1 to 50 μm or more of pushing, foreign matter, and dirt were observed.
10 pieces were observed and 31 to 50 pieces having a size of 50 μm or less were observed. D: 11 pieces of pressed / foreign matter / dirt having a size of 50 μm or more were found.
Up to 30 pieces were observed, and 51 or more pieces having a size of 50 μm or less were observed.

(Number of shining spots on polarizing plate) 25 cm × 2
Five polarizing plate samples cut into a size of 5 cm were prepared for each sample, and crossed Nicols having a size of 30 cm × 30 cm were prepared. The number of shining spots appearing on a dark surface due to a foreign substance or the like was observed. Were evaluated at the following levels.

A: No bright spots were observed. B: 1 to 5 small bright spots were observed. C: 6 to 30 small bright spots were observed. D: 31 to 50 bright spots were observed. E : 51 or more brilliant spots were observed.

Embodiment 1 Embodiment 1 relates to the first to fifth and twelfth and thirteenth aspects.

[Preparation of sample] (Preparation of dope) Cellulose triacetate having an acetyl substitution degree of 2.88 (number average molecular weight: 150,000) 100 parts by mass Triphenyl phosphate 10 parts by mass Ethyl phthalyl ethyl glycolate 2 parts by mass Tinuvin 326 1 Parts by mass AEROSIL 200V 0.1 parts by mass Methylene chloride 475 parts by mass Ethanol 25 parts by mass The above composition is charged into a closed vessel and dissolved with stirring to prepare a cellulose ester dope. Absolute filtration accuracy 0.0
Using a filter paper of 05 mm, filtration flow rate 300 l / m ² · hour,
Filtration was performed at a filtration pressure of 1.0 × 10 ⁶ Pa.

(Casting and Drying) The dope was cast on a stainless steel belt through a die, the temperature of the stainless steel belt was controlled at 25 ° C., and a wind of 45 ° C. was blown from the web side at a wind speed of 10 m / sec. Obliquely, in the portion where the stainless steel belt was on the lower side, the first half was vertically blown with a wind of 40 ° C. at 10 m / sec to dry the web, and the solvent was evaporated until the residual solvent amount in the web became 25% by mass. Peeled off. After peeling, Table 1
The web was brought into contact with the roll having the surface roughness Ry, diameter, surface material, and arrangement changed by the tension shown in Table 1 and transported. In addition, about the roll arrangement | positioning of Table 1, 1: The roll shown in Table 1 is arrange | positioned to all ten rolls including a peeling roll. 2: The roll shown in Table 1 is arrange | positioned to all nine except peeling rolls. : Arrangement of peeling rolls and subsequent three rolls described in Table 1 4: Five rolls including only peeling rolls and the rolls of Table 1 contacting the A side of the web including the peeling rolls 5: Described in Table 1 from the fifth roll The rolls were arranged as shown. Thereafter, the web is introduced into a tenter dryer as described in JP-A-62-115035 and dried at 90 to 110 ° C. while keeping the width, and subsequently, a roll dryer in which the webs are arranged in a staggered manner. At 110-13
Dried at 0 ° C. Finally, the film was cooled to 20 ° C. to obtain a cellulose triacetate film having a winding thickness of 40 μm. After performing this film formation for 24 hours, the rolls were exchanged for each roll, and the film formation was performed once, and then the film formation was performed again while replacing the rolls again. Test No. Each time, the first and second cellulose ester film samples were taken.

The obtained first and second cellulose ester films were immersed in a 2 mol / l aqueous solution of sodium hydroxide at 60 ° C. for 2 minutes and washed with water.
For 10 minutes to obtain a protective film for a polarizing plate, which was obtained by an alkali saponification treatment. Separately, a polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer (polarizing film). The protective film for a polarizing plate was bonded to both surfaces of the polarizer using a 5% aqueous solution of a completely saponified polyvinyl alcohol as an adhesive to prepare a polarizing plate. Pressing, foreign matter, and contamination of the film were observed, and the number of shining spots on the polarizing plate was evaluated. The results are shown in Table 1.

[0068]

[Table 1]

(Results) The pressing of a cellulose ester film using a roll having a surface roughness Ry of 0.6 μm or less, which was plated with hard chromium, and was subjected to
The one using the Teflon roll was not pressed, the foreign matter and the dirt were not pressed at the first time, while the one using the Teflon roll was good. I understand. It was found that a hard chrome plating roll having a surface roughness Ry of more than 0.6 was liable to stain. In the arrangement of the rolls, the use of the hard chromium-plated roll of the present invention as the peeling roll is necessary and sufficient to obtain a film free of dirt and the like, and it is possible to use the roll of the present invention as early as possible. It turned out to be important.

Embodiment 2 This embodiment 2 relates to the inventions of claims 6 to 11 and 12 and 13.

The dope of Example 1 was cast on a stainless steel belt through a die, the temperature of the stainless steel band was controlled at 25 ° C., and a wind of 45 ° C. was blown from the web side at a wind speed of 10 m / sec. At the portion where the stainless steel belt is on the lower side, the first half is vertically blown with a wind of 40 ° C. at 10 m / sec to dry the web, and the solvent is evaporated until the amount of residual solvent in the web becomes 25% by mass. And peeled off. After peeling, the surface roughness Ry 0.7 μm plated with hard chrome as a roll
Rolls are arranged in a zigzag pattern before the web is introduced into the drying device and conveyed. Thereafter, the web is introduced into a tenter dryer as described in JP-A-62-115035 and the width is maintained. While drying at 90 to 110 ° C., and then using a roll dryer in which the web is arranged in a zigzag pattern.
Dried at 30 ° C. Finally, the film was cooled to 20 ° C. to obtain a cellulose triacetate film having a winding thickness of 40 μm. As shown in Table 2, a cleaning means was provided, the organic solvent was applied (symbol: Y), and the wiping means (symbol W) was used. The cleaning means was moved at a speed of 5 mm / min. In addition, a test was conducted for a sample that was not cleaned (symbol: N). Bencott was used as the nonwoven fabric. Film formation was continuously performed for 72 hours, and cellulose ester film samples were collected after 24 hours and 72 hours.

The obtained cellulose ester films after 24 hours and 72 hours were immersed in a 2 mol / l aqueous solution of sodium hydroxide at 60 ° C. for 2 minutes and washed with water.
An alkali-saponified protective film for a polarizing plate obtained by drying at 100 ° C. for 10 minutes was produced. Separately, thickness 12
A 0 μm polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer (polarizing film). The protective film for a polarizing plate was bonded to both surfaces of the polarizer using a 5% aqueous solution of a completely saponified polyvinyl alcohol as an adhesive to prepare a polarizing plate. Pressing, foreign matter, and contamination of the film were observed, and the number of shining spots on the polarizing plate was evaluated. The results are shown in Table 2.

[0073]

[Table 2]

(Results) It has been found that it is effective to first apply the organic solvent to the roll immediately after the web is separated from the roll, and then wipe it, in order to eliminate stains and the like using the cleaning means. It was also found that if the cleaning order was incorrect, dirt and the like would be worse. It turned out that the effect does not change even if a nonwoven fabric is used as a pad or a continuous cloth.

[0075]

As described above, it is possible to provide a cellulose ester film suitable for a thin protective film for a polarizing plate, which is almost free from dirt, pushing, and foreign matter.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a solution casting film-forming cellulose ester film manufacturing apparatus.

FIG. 2 is a schematic view of a solution casting film-forming cellulose ester film manufacturing apparatus having a tenter drying apparatus.

FIG. 3 is a schematic view of a movable cleaning unit and a roll as viewed from the direction.

FIG. 4 is a perspective view of the cleaning unit viewed from a roll axis direction.

FIG. 5 is a perspective view of the cleaning unit viewed from a roll axis direction.

DESCRIPTION OF SYMBOLS 1 Dope film (web) 2 Die 3 Metal support 4 Peeling roll 5 Roll drying device 9 Tenter drying device 11 Roll 20 Cleaning means 21 Organic solvent adhesion pad 22 Organic solvent pool 23 Wiping pad 24 Movable table 25 Stand having rails 26 Nonwoven fabric for attaching organic solvent 27 Organic solvent supply roll 28 Organic solvent supply source 29 Nonwoven fabric for wiping 30 Nonwoven fabric original winding 31 Nonwoven fabric winding

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) B29L 7:00 B29L 7:00 C08L 1:10 C08L 1:10 F term (reference) 2H049 BB33 BC09 BC22 4F071 AA09 AG36 AH16 BA02 BB02 BC01 BC12 4F205 AA01 AC05 AG01 AH42 AM10 AR13 AR20 GA07 GB02 GC07 GF24 GN21 GN24 GN28 GN29

Claims (13)

[Claims] (1) using a solution casting film forming apparatus to form a film having a film thickness of 20 to
In a method of producing a cellulose ester film having a thickness of 80 μm, a web having a residual solvent amount of 10 to 150% by mass after peeling is formed by forming a web having a surface roughness Ry of 0.6 μm or less and 20 ° C.
A method for producing a cellulose ester film, wherein the film is conveyed while being in contact with a roll having a surface energy of 70 to 100 mN / m. 2. The method for producing a cellulose ester film according to claim 1, wherein the first one of the rolls is a release roll. 3. The production of a cellulose ester film according to claim 1, wherein the roll is only a roll that contacts the air-side surface of the web on an endless metal support that moves infinitely. Method. 4. The method for producing a cellulose ester film according to claim 1, wherein the roll is hard chromium-plated. 5. The method for producing a cellulose ester film according to claim 1, wherein the diameter of the roll is 85 to 300 mm. 6. A solution casting film forming apparatus having a roll and a roll surface cleaning means, wherein the cleaning means moves in the axial direction of the roll while adhering an organic solvent to the roll, and the roll is disposed adjacent to the roll. An apparatus for producing a cellulose ester film, comprising means for wiping the surface. 7. A means for attaching an organic solvent to a roll,
The apparatus for producing a cellulose ester film according to claim 6, wherein the means for supplying an organic solvent by capillary action is provided. 8. The apparatus for producing a cellulose ester film according to claim 6, wherein the wiping means has a nonwoven fabric. 9. The method according to claim 6, wherein the means for adhering the organic solvent has a nonwoven fabric containing the organic solvent.
An apparatus for producing a cellulose ester film according to any one of the above. 10. A cellulose ester film, wherein the web is transported while contacting the web with a roll wiped and cleaned by applying the organic solvent by the means according to any one of claims 6 to 9. Production method. 11. The method according to claim 1, wherein the organic solvent is a good solvent having a solubility in cellulose ester, or the organic solvent is a mixture of a good solvent having a solubility in cellulose ester and a poor solvent having no solubility. Claim 1.
0. The method for producing a cellulose ester film according to item 0. 12. A cellulose ester film produced by the method according to claim 10. 13. A polarizing plate using the cellulose ester film according to claim 12.