JP2000344904A - Production of cellulose ester film and cellulose ester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for obtaining cellulose ester film having excellent quality by preparing cellulose ester dope without using a chlorine-based solvent. SOLUTION: In a method for producing cellulose ester film by a solution casting film forming method using a cellulose ester having a 2-4C acyl group as substituent, a cellulose ester simultaneously meeting following formulas I and II (wherein X is a substitution degree of acetyl group and; Y is a substitution degree of propionyl group and/or butyryl group) is dissolved in a non- chlorine organic solvent containing 0.1-30 wt.% (based on the total weight of all organic solvents) alcohol selected from 1-4C alcohols to prepare dope, and film is formed using the dope: (I) 2.6<=X+Y<=3.0 and; (II) 0<=X<=2.5. A web easily comes off a casting substrate plate and cellulose ester film not having defects such as transverse die lines can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cellulose ester film useful for a silver halide photographic material, a liquid crystal image display device and the like, and a cellulose ester film.

[0002]

2. Description of the Related Art At present, cellulose triacetate films are preferably used for silver halide photographic materials and liquid crystal image display devices because of their transparency and properties free from optical defects, and the required quality is increasing year by year. .

Conventionally, in the process of producing a cellulose triacetate film, if there is any undissolved material during the dissolution of the dope, it remains as a small foreign substance on the film surface even after the film is formed, and the adhesion between the web and the casting support. If the web is too strong, when the web is peeled off from the casting support, defects such as horizontal unevenness and unevenness occur, and the surface quality of the film is remarkably reduced.

Further, the use of chlorinated hydrocarbon solvents such as methylene chloride, which is a good solvent for cellulose esters represented by cellulose triacetate, tends to be environmentally restricted. There is a demand for a manufacturing method that does not.
However, it is difficult to obtain a good quality dope by replacing the solvent for the cellulose ester with a non-chlorine organic solvent.

The following proposals have been made in response to the above requirements. As a method for reducing the adhesion between the web and the casting support, a method is disclosed in JP-A-4-277530, in which a cotton linter and pulp, which are raw materials for cellulose triacetate, are each acetylated and then acetylated. There is a proposal to make a percentage. This method has an effect when a cellulose triacetate dope is used with a chlorine-based organic solvent such as methylene chloride, but does not necessarily have a sufficient effect when a non-chlorine-based organic solvent is used. Was. Furthermore, it was not very effective for cellulose esters other than cellulose triacetate.

In addition, a method has been proposed for preparing a cellulose triacetate dope in which acetone or methyl acetate is used instead of a chlorine-based organic solvent such as methylene chloride without using a non-chlorine-based organic solvent. ing.
For example, Japanese Patent Application Laid-Open Nos. 9-95544 and 9-95557 propose a cooling dissolution method using an organic solvent consisting essentially of acetone, or using methyl acetate or acetone and another non-chlorine organic solvent. ing. JP-A-9-95538 discloses a method of dissolving by cooling using an organic solvent selected from ethers, ketones or esters other than acetone, and JP-A-11-21379 discloses mixing cellulose triacetate with acetone. , A method of applying a pressure of 10 to 5000 kg / cm ² has been proposed. In Japanese Patent Application Laid-Open No. 10-45804, a film is formed using a mixed fatty acid ester of cellulose which is soluble in a solvent such as acetone or methyl acetate and has an acetyl group and an acyl group having 3 or more carbon atoms having a specific relationship. A way to do that has been proposed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing a cellulose ester dope without using a chlorine-based solvent to obtain a cellulose ester film of good quality. An object of the present invention is to provide a method for producing a cellulose ester film which can easily peel a web from a casting support and does not cause defects such as horizontal steps.

[0008]

The present invention has the following constitution.

(1) A method for producing a cellulose ester film by a solution casting method using a cellulose ester having an acyl group having 2 to 4 carbon atoms as a substituent, wherein X represents an acetyl group substitution degree, When the degree of substitution of a propionyl group and / or a butyryl group is Y, a cellulose ester satisfying the following formulas (I) and (II) at the same time is converted from an alcohol selected from those having 1 to 4 carbon atoms with respect to the total organic solvent. A method for producing a cellulose ester film, comprising: dissolving a dope in a non-chlorine-based organic solvent containing 0.1 to 30% by weight to form a dope; and forming the film using the dope.

(I) 2.6 ≦ X + Y ≦ 3.0 (II) 0 ≦ X ≦ 2.5 (2) Solution casting using a cellulose ester having an acyl group having 2 to 4 carbon atoms as a substituent. In a method for producing a cellulose ester film by a film forming method,
When the degree of substitution of an acetyl group is X and the degree of substitution of a propionyl group and / or a butyryl group is Y, the following formula (III):
And (IV) are simultaneously dissolved in a non-chlorinated organic solvent containing an alcohol selected from those having 1 to 4 carbon atoms in an amount of 1% by weight or more and less than 10% by weight based on the total organic solvent. A method for producing a cellulose ester film, wherein a film is formed using the dope.

(III) 2.6 ≦ X + Y ≦ 3.0 (IV) 2.5 <X ≦ 3.0 (3) The dope is 1 to 1 with respect to the cellulose ester.
The method for producing a cellulose ester film according to (1) or (2), comprising 0% by weight of alkylphthalylalkyl glycolate.

(4) The temperature range of the entire surface of the casting support in the solution casting film forming method is set to 10 to 60 ° C., and the temperature of the dope is set to the temperature of the dope casting position of the casting support. The method for producing a cellulose ester film according to any one of (1) to (3), wherein the film is cast on the casting support at least as high as the above.

(5) A cellulose ester dope is cast on a casting support to form a web, and the temperature of the casting support at a web peeling position on the casting support is 10 to 4
The cellulose ester according to any one of (1) to (4), wherein the web is peeled when the temperature is 0 ° C. and the amount of the residual solvent of the web at the peeling position is 20 to 100% by weight. Film production method.

(6) The cellulose ester film according to any one of (1) to (5), wherein the dope contains 0.5 to 5% by weight of water based on the cellulose ester. Production method.

(7) The cellulose ester film according to any one of (1) to (6), wherein the dope contains acetic acid in an amount of 0.1 to 2% by weight based on the cellulose ester. Production method.

(8) The cellulose ester is 70,000
The method for producing a cellulose ester film according to any one of (1) to (7), which has a number average molecular weight of 300,000.

(9) The method for producing a cellulose ester film according to any one of (1) to (8), wherein Y is a degree of substitution of a propionyl group.

(10) The method for producing a cellulose ester film according to any one of (1) to (9), wherein the non-chlorine organic solvent is methyl acetate.

(11) The method for producing a cellulose ester film according to any one of (1) to (10), wherein the alcohol is ethanol.

(12) The method for producing a cellulose ester film according to any one of (1) to (11), wherein the dope contains 10 to 40% by weight of a cellulose ester.

(13) Any one of (1) to (12)
13. A cellulose ester film produced by the method described in item 9.

Hereinafter, the present invention will be described in detail.

In the present invention, the cellulose ester solution is called a cellulose ester dope or simply a dope.

First, a method for forming a cellulose ester film by the solution casting method according to the present invention will be described.

Dissolution step: This step is a step of dissolving the flakes in an organic solvent mainly containing a good solvent for cellulose ester flakes in a dissolving vessel while stirring to form a dope. For dissolution, a method performed at normal pressure, a method performed at a temperature lower than the boiling point of the main solvent, a method performed at a pressure equal to or higher than the boiling point of the main solvent, a method performed by a cooling dissolution method as described above, a method performed at a high pressure as described above, etc. There is a dissolution method. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next step by a pump.

In the dope, a plasticizer, an antioxidant, a dye and the like are sometimes added. For silver halide photographic light-sensitive materials, a plasticizer is added to improve mechanical properties or impart flexibility, and a coloring agent for preventing light piping or an ultraviolet inhibitor is added. The colorant is preferably a colorant which can be colored gray as seen in a normal photographic support, and the content is preferably from 10 to 1000 ppm by weight relative to the cellulose ester, and 50 pp.
m to 500 or less is more preferable. By including a colorant in this way, the fogging phenomenon due to light piping in a silver halide photographic material can be eliminated. These compounds may be added together with the cellulose ester or the solvent when preparing the cellulose ester solution, or may be added during or after the solution is prepared. For liquid crystal display devices, plasticizers that provide heat and moisture resistance,
It is preferable to add an antioxidant or an ultraviolet inhibitor.

As the antioxidant, hindered phenol compounds are preferably used, and 2,6-di-t is 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)
-Isocyanurate and the like. 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-tert-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, kaolin, talc, diatomaceous earth,
Heat stabilizers such as inorganic fine particles such as quartz, calcium carbonate, barium sulfate, titanium oxide and alumina, and salts of alkaline earth metals such as calcium and magnesium may be added. Further, an antistatic agent, a flame retardant, a lubricant, an oil agent and the like may be added in some cases.

Casting step: The dope is fed to a pressurizing die through a pressurized metering gear pump, and at the casting position, an endless metal belt or a support for rotating a rotating metal drum (hereinafter simply referred to as a casting support). This is a step of casting a dope from a pressure die onto a support. The surface of the casting support is a mirror surface. Other casting methods include a doctor blade method of adjusting the film thickness of the cast dope film with a blade, a method using a reverse roll coater that adjusts with a roll that rotates in reverse, and the like.
A pressure die that can adjust the slit shape of the base and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used.
Place a pressure die on the casting support to increase the film forming speed.
It is also possible to provide more than a group, and to divide the doping amount to form an overlying layer.

Solvent evaporation step: a step of heating a web (the web is referred to as a dope film after casting the dope on the casting support) on the casting support to evaporate the solvent. . 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. Good drying efficiency is preferable.
A method of combining them is also preferable.

Peeling step: This is a step of peeling the web from which the solvent has evaporated on 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, the web is difficult to peel, or conversely, if the web is sufficiently dried on the support and then peeled, a part of the web is peeled off in the middle.

As a method of increasing the film forming speed (the film forming speed can be increased because the film is peeled while the amount of the residual solvent is as large as possible), there is a gel casting method in which the film can be peeled even with a large amount of the residual solvent. . 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 and strengthening the film, peeling can be accelerated and the film forming speed can be increased. If the residual solvent amount is greater at the time of peeling, if the web is too soft, the flatness at the time of peeling may be impaired, or shear or vertical stripes may easily occur due to peeling tension, and the amount of the residual solvent may be reduced in consideration of economic speed and quality. I can decide.

Drying step: This is a step of drying the web 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 by clipping both ends of the web with clips. In general, hot air is blown to both sides of the web as a drying means, but there is also a method of heating by applying a microwave instead of the 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 weight or less. Throughout, the drying temperature is usually 40 to 250 ° C, preferably 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 off from the surface of the casting support, the web tends to shrink in the width direction due to evaporation of the solvent. The quicker it dries at higher temperatures, 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. 62-4662.
The method of drying all the steps or a part of the steps as described in Japanese Patent Publication No. 5 (tenter method) while holding both ends of the width of the web with a clip in the width direction is preferable.

Winding step: The web is treated with a residual solvent amount of 2
In this step, the film is wound up as a film after the amount becomes less than the weight%. By setting the amount of the residual solvent to 0.4% by weight or less, a film having good dimensional stability can be obtained. 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 amount of the residual solvent can be expressed by the following equation.

Residual solvent amount (% by weight) = {(M−N) / N} × 100 where M is the weight of the web at any time, and N is M
Weight when dried at 0 ° C. for 3 hours.

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 particularly preferable for a film for a liquid crystal image display device. To adjust the film thickness, it is necessary to control 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. so that the desired thickness is obtained. Good. In addition, as means for making the film thickness uniform, it is preferable to use a film thickness detecting means to feed back and adjust the programmed feedback information to each of the above-described devices.

In the process from the step immediately after casting to the step of drying through the solution casting film forming method, the atmosphere in the drying apparatus may be air, but the drying is performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. You may. 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 configuration (1) of the present invention will be described.

The constitution (1) of the present invention has 2 to 4 acyl groups as substituents, the substitution degree of an acetyl group is X, and the substitution degree of a propionyl group and / or a butyryl group is Y, and the following formula: (I) and (II) (I) 2.6 ≦ X + Y ≦ 3.0 (II) A cellulose ester satisfying 0 ≦ X ≦ 2.5 at the same time was obtained by converting a cellulose ester having 1 carbon atom into 1
The cellulose ester dope is dissolved in a chlorine-free organic solvent containing 0.1 to 30% by weight of the alcohol of the formula (1) to (4) with respect to the total organic solvent to obtain a cellulose ester dope. This is a method for producing a cellulose ester film.

The usage of the word “and / or” in the present invention is synonymous with “selected from” or “at least one selected from”.

The cellulose as a raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, 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 of the present invention may be an organic solvent such as acetic acid or an organic solvent such as methylene chloride. And using a protic catalyst such as sulfuric acid. The acylating agent is an acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H
_In the case of ( ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by the method described in JP-A-10-45804. The cellulose ester of the constitution (1) is obtained by adjusting and mixing the amount of the acylating agent according to each degree of substitution and reacting. In the cellulose ester, these acyl groups react with the hydroxyl groups of the cellulose molecule. Cellulose molecules are composed of a large number of linked glucose units, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution (mol%). For example, in cellulose triacetate, all three hydroxyl groups of a glucose unit are bonded to an acetyl group (actually, 2.6 to 3.0).

The cellulose ester of the constitution (1) is a cellulose ester such as cellulose acetate propionate, cellulose acetate butyrate or cellulose acetate propionate butyrate, to which a propionate group or a butyrate group is bonded in addition to an acetyl group. . In addition, propionate is iso in addition to n-.
-, Butyrate is iso-, sec-, t in addition to n-
ert- also includes each. Cellulose acetate propionate having a high degree of substitution of propionate groups has excellent water resistance and is useful as a film for a liquid crystal image display device.

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

The number average molecular weight of the cellulose ester used in the present invention (configuration (8) of the present invention) is from 70,000 to 3
The range of 00000 is preferable because the mechanical strength when molded is high. Furthermore, 80,000 to 200,000 are preferable.

The chlorine-free organic solvents useful for forming the dope of the constitution (1) include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolan, 1,4-dioxane, cyclohexanone, and ethyl formate. , 2,2,2-trifluoroethanol, 2,2
3,3-hexafluoro-1-propanol, 1,3-
Difluoro-2-propanol, 1,1,1,3,3,
3-hexafluoro-2-methyl-2-propanol,
1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane and the like can be mentioned, and methyl acetate, ethyl acetate, Acetone may preferably be used.

The feature of the cellulose ester of the constitution (1) is that it can be dissolved in methyl acetate, ethyl acetate and / or acetone at room temperature, and methyl acetate is particularly preferred (the constitution (10)).

In the cellulose ester dope of the constitution (1), in addition to the above-mentioned non-chlorine organic solvent, 0.1 to 30% by weight
Alcohols having 1 to 4 carbon atoms are contained. However, after casting the dope on the casting support, the solvent starts to evaporate, and when the ratio of the alcohol increases, the web (dope film) gels and the web becomes It is used as a gelling solvent that is strong and easy to peel off from the casting support, and when these are in a small proportion, they also have a role to promote the dissolution of the cellulose ester of the non-chlorine organic solvent. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol,
Examples thereof include sec-butanol and tert-butanol. Among them, ethanol is preferable because of its stability, the boiling point is relatively low, the drying property is good, and there is no toxicity (configuration (11)).

The solid content of the dope is usually preferably from 10 to 40% by weight (structure (12)), and the viscosity of the dope is preferably from 100 to 40% by weight.
It is prepared in the range of 500 poise.

The structure (2) of the present invention has 2 to 4 acyl groups as substituents, the substitution degree of an acetyl group is X, and the substitution degree of a propionyl group and / or a butyryl group is Y, and the following formula: (III) and (IV) (III) 2.6 ≦ X + Y ≦ 3.0 (IV) A cellulose ester which simultaneously satisfies 2.5 <X ≦ 3.0 was converted to a cellulose ester having 1 carbon atom.
1 to 4% by weight based on the total organic solvent
This is a method for producing a cellulose ester film in which a cellulose ester dope is formed by dissolving in a non-chlorine-based organic solvent containing less than 0% by weight, and the dope is formed by a solution casting method.

The above formulas (III) and (IV) of the present configuration (2)
Are simultaneously substituted with a low degree of Y, that is, a propionyl group and / or a butyryl group, and most of them are acetyl groups, and preferably, X = 2.6-3.
0, substantially cellulose triacetate with Y = 0, or cellulose ester closer to cellulose triacetate. The cellulose triacetate film has high mechanical strength and is useful as a film for a silver halide photographic light-sensitive material or a film for a liquid crystal image display device.

The acyl group having 3 or 4 carbon atoms in the constitution (1) or (2) is preferably a propionyl group in the present invention (the constitution (9)).

As the non-chlorine organic solvent of the constitution (2), the above-mentioned organic solvent (same as the constitution (1)) can be used.
Methyl acetate and / or acetone are preferred as in the configuration (1), and methyl acetate is particularly preferred. However, it is difficult to dissolve by means of dissolution at room temperature, and it is preferable to use a high-temperature dissolution method or a cooling dissolution method. The method of forming a dope using a solvent such as acetone, methyl acetate, and ethyl formate described in JP-A-9-95538, JP-A-9-95544, and JP-A-9-95557 can be used. Further, the high-pressure melting method described in JP-A-11-21379 can also be preferably used.

The alcohols to be added to the non-chlorine solvent are
Same as (Structure (1)), but when contained in an amount of 1% by weight or more and less than 10% by weight, solubility is promoted where the content is small, and gelation is exerted where the content is large. However, when the content is 10% by weight or more, solubility becomes difficult.

The number average molecular weight and dope concentration of the cellulose ester are the same as those described in the constitution (1) (the constitutions (8) and (12)).

The constitution (3) of the present invention is characterized in that, in the method for producing a cellulose ester film according to the constitution (1) or (2), 1 to 10% by weight of an alkylphthalylalkylglycolate ( Alkyloxyphthaloyloxyacetate) in a cellulose ester dope.

The present inventors have found that the inclusion of alkylphthalylalkyl glycolate in the dope reduces the adhesion between the casting support and the web when the web is peeled from the casting support. It has been found that the method can be performed (the peeling force can be reduced), and thus the web can be peeled even in a state of a high residual solvent amount. This not only can improve the film forming speed, but also improves the quality of the finished film due to the small peeling force, and in another aspect, significantly increases the water resistance of the film compared to other plasticizers. Can be improved. Conventionally, alkyl phthalyl alkyl glycolate has been used as an auxiliary plasticizer for phosphate esters such as triphenyl phosphate, but its effect was not clearly understood,
The present inventors have found that the active use has an excellent effect.

The alkyl of the alkylphthalylalkyl glycolate is an alkyl group having 1 to 8 carbon atoms.

Examples of the alkylphthalylalkyl glycolate include methylphthalylmethyl glycolate, ethylphthalylethyl glycolate, propylphthalylpropyl glycolate, butylphthalylbutyl glycolate, octylphthalyloctyl glycolate, and methylphthalyl. Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl Glycolate, butylphthalylethyl glycolate, propylphthalylbutylglycolate, butylphthalylpropylglycolate, methylphthalyloctylglycolate, ethylphthalate Octyl phthalyl methyl glycolate, octyl phthalyl ethyl glycolate, etc., such as methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, and butyl phthalyl butyl. Glycolate and octylphthalyloctyl glycolate are preferred, and ethylphthalylethyl glycolate is particularly preferred. Further, two or more of these alkylphthalylalkyl glycolates may be used in combination.

The amount of the alkylphthalylalkyl glycolate to be added is 1 to 100 parts with respect to the cellulose ester from the viewpoint of improving the releasability and suppressing bleed-out from the film.
10% by weight is preferred. In the present invention, the following general plasticizer may be mixed together with the alkylphthalylalkyl glycolate, but added in a smaller amount than the alkylphthalylalkyl glycolate to such an extent that the effect of the alkylphthalylalkyl glycolate is not impaired. Is preferred.

Other general plasticizers may be added for the purpose of improving mechanical properties and imparting flexibility, and phosphate esters and carboxylate esters are usually used.
For example, examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, phenyldiphenyl phosphate, and the like. Examples of carboxylic acid esters include phthalic acid esters and citric acid esters, and examples of phthalic acid esters include dimethyl phthalate, diethyl phosphate, dioctyl phthalate and diethylhexyl phthalate, and examples of citrate esters include acetyl triethyl citrate and acetyl citrate. Tributyl can be mentioned. Other examples include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and triacetin.

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 preparation.

The structure (4) of the present invention comprises the structures (1) to
In the method for producing a cellulose ester film of (3), the temperature range of the entire surface of the support for casting in the solution casting film forming method is set to 10 to 60 ° C., and the temperature of the cellulose ester dope is further adjusted to the dope of the support. It is preferable to set the dope temperature higher by 5 ° C. or higher by a method of casting at a temperature equal to or higher than the casting position. In order to evaporate efficiently, the dope temperature is preferably set to a temperature that does not cause foaming, that is, the boiling point of the main organic solvent to be used is not higher than 30 to 80 ° C.
Is preferred. The boiling point of the main organic solvent preferably used in the present invention is represented by methyl acetate (boiling point: 56.32).
° C), acetone (56.3 ° C), ethyl acetate (76.8).
2 ° C.).

The configuration (5) of the present invention comprises the configurations (1) to
In the method for producing a cellulose ester film of (4), a cellulose ester dope is cast on a casting support to form a web, and the temperature at a peeling position on the support is 10 to 40 ° C., preferably 15 to 30 ° C. This is a method in which the web is peeled off at a time when the temperature is set to 20 ° C. and the amount of the residual solvent of the web at the peeling position is 20 to 100% by weight to facilitate the peeling and form a film. In order to obtain such a residual solvent amount at the time of peeling, it is necessary to control the surface temperature of the casting support after the casting, and to keep the temperature within the above temperature range so that the organic solvent can be efficiently evaporated from the web. There is. To control the support temperature,
It is better to use a heat transfer method with good heat transfer efficiency. For example,
A backside heat transfer method using a liquid is preferred. The heat transfer method using radiant heat or hot air is not preferable because it is difficult to control the temperature of the support. However, in a belt (support) machine, the temperature control where the belt to be transferred comes to the lower side is moderate. The belt temperature can be adjusted with a gentle breeze.
The temperature of the support can be partially changed by dividing the heating means, and can be set to different temperatures such as a casting position, a drying section, and a peeling position of the casting support.

In particular, a combination of the constitutions (5), (3) and (4) makes it possible to obtain a cellulose ester film which is easily peeled and has excellent flatness.

The configuration (6) of the present invention comprises the configurations (1) to
(5) The method for producing a cellulose ester film according to (5), wherein water is added in the dope to the cellulose ester in an amount of 0.5%.
When the content is about 5% by weight, peeling becomes easy and a film having excellent flatness can be obtained. Water is usually present in the produced cellulose ester flakes in an amount of 0.1%.
Although it is present in an amount of 5% by weight or less, the adhesiveness between the support and the web is reduced when peeling is performed by positively adding more than 5% by weight, thereby facilitating peeling. In the film after drying,
The water also evaporates to a water content of 0.1% by weight or less, and at such a level, the properties of the cellulose ester film are not affected.

The configuration (7) of the present invention comprises the configurations (1) to
In the method (5) for producing a cellulose ester film, acetic acid is added to the cellulose ester in a dope in an amount of 0.1 to 0.1%.
By containing 1 to 2% by weight, peeling becomes easy similarly to the above-mentioned water, and a film having excellent flatness can be obtained. Acetic acid is present as a free acid in the produced cellulose ester flakes in an amount of 0.01% by weight or less, but when added more aggressively, the adhesion between the support and the web is reduced when peeled off. And easily peel off. However, in the film after drying, acetic acid can be evaporated to 0.01% by weight or less, and it is better not to leave acetic acid in the film as much as possible. In the present invention, 0.005% by weight or less is used. It can be.

The water or acetic acid of the constitution (6) or (7) may be mixed in a solvent in advance, or may be added together with the cellulose ester at the time of dissolution. Further, it may be added in the dope.

When the constitution (6) or (7) is used together with the alkylphthalylalkyl glycolate of the constitution (3), the adhesion can be further reduced. Further configuration (6)
Or (7) may be used at the same time, and the effect can be improved.

The structure (13) of the present invention comprises the structures (1) to
It is a cellulose film formed by the method for producing a cellulose ester film of (12). In particular, the cellulose ester film produced by the present invention is particularly useful as a film for a liquid crystal image display device.

Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto.

[0073]

EXAMPLES Each measurement and evaluation method in the examples was carried out by the following methods.

<Degree of Substitution of Cellulose Ester> The degree of substitution is measured by a saponification method. The dried cellulose acylate is precisely weighed and dissolved in a mixed solvent of acetone and dimethyl sulfoxide (volume ratio of 4: 1).
A predetermined 1N aqueous sodium hydroxide solution is added, and saponification is performed at 25 ° C. for 2 hours. Phenolphthalein is added as an indicator and excess sodium hydroxide is titrated with 1N sulfuric acid. A blank test is performed in the same manner as described above. Further dilute the supernatant of the solution after the titration,
The composition of the organic acid is measured by a conventional method using an ion chromatograph. Then, the degree of substitution (%) is calculated as follows.

TA = (Q−P) × F / (1000 × W) DSace = (162.14 × TA) / ｛1-42.1
4 × TA + (1-56.06 × TP) × (AL / A
C)｝ DSacy = Ssce × (AL / AC) where P is the amount of 1N sulfuric acid (ml) required for titration of the sample, Q
Is the amount of 1N sulfuric acid required for the blank test (ml), F is 1
N sulfuric acid titer, W is sample weight, TA is total organic acid amount (mo
l / g), AL / AC is the molar ratio of acetic acid (AC) to another organic acid (AL) as measured by ion chromatography, DS
ace indicates the degree of substitution of the acetyl group, and DSacy indicates the degree of substitution of the acyl group having 3 or 4 carbon atoms.

<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 W / v% Flow rate: 1.0 ml / min Sample injection volume: 300 μl Standard sample: polymethyl methacrylate (Mw = 188) , 2
00) Temperature: 23 ° C.

<Adhesion between Film and Support> The film cast on the support and dried on the support is peeled off in a direction perpendicular to the support. The force required to peel a 100 mm wide film was determined using a spring balance.

<Film horizontal unevenness> The peeled film obtained in the above measurement was visually observed, and the level of the horizontal unevenness was ranked as follows.

A: Smoothness without horizontal step-like unevenness at all B: Feels as though slight horizontal step-like unevenness is visible, but overall smooth C: Although horizontal step-like unevenness is slightly visible D: Horizontal step-like unevenness is slightly visible, and slightly lacks smoothness. E: Horizontal step-like unevenness is clearly seen, but the amount is not so large. F: Many clear horizontal step-like unevenness is seen.

Preparation of the cellulose ester films of Examples 1 to 12 and Comparative Examples 1, 2 and 4.

The cellulose ester shown in Table 1 was charged into a pressurized airtight container having the dope composition shown in Table 1, heated to 80 ° C., and the pressure in the container was set to 2 atm. To obtain a dope. After the temperature of the dope was lowered to a casting temperature, the solution was allowed to stand overnight, and then subjected to a defoaming operation. After that, the solution was subjected to Azumi Filter Paper No. After filtration using 244, the mixture was subjected to film formation.

Production of the cellulose ester films of Examples 13 to 15 and Comparative Example 3.

The cellulose triacetate shown in Table 1 was swelled with the dope composition shown in Table 1 at room temperature in a container in which a solvent had been introduced. Next, put this mixture in a double-layered closed container,
The refrigerant was introduced into the outer jacket while stirring the mixture slowly. This allows the mixture in the inner container to reach -70 ° C.
Cooled down. The mixture was cooled for 30 minutes until it was cooled uniformly. The refrigerant in the jacket outside the sealed container is discharged, and warm water is introduced into the jacket instead. The contents were subsequently stirred and raised to 80 ° C. over 40 minutes. The pressure in the container became 2 atm. The temperature was lowered to 50 ° C. with stirring and returned to normal pressure, and the mixture was left overnight to obtain a dope. Azumi Filter Paper No. No. manufactured by Azumi Filter Paper Co., Ltd. The mixture was filtered using 244 and subjected to film formation.

The above (Examples 1 to 15 and Comparative Examples 1 to 4)
The dope was adjusted to the temperature shown in Table 1 and cast from a die onto a stainless steel belt so as to have a film thickness after drying shown in Table 1.
After hot water of the temperature shown in Table 1 was brought into contact with the back surface of the stainless steel belt and dried on a stainless steel belt whose temperature was controlled for 5 minutes, cold water shown in Table 1 was further brought into contact with the back surface of the stainless steel belt and held for 1 minute. After that, it was peeled off from the stainless steel. At this time, cuts were made at intervals of 100 mm on the belt, and the adhesion was measured using a spring balance.

Further, the web at a different position from the above-mentioned adhesion test was peeled off from the belt while keeping the peeling speed and the peeling force constant. The film was dried at 130 ° C. for 30 minutes while fixing both ends of the peeled film so as to prevent noise such as shrinkage of the film. The resulting film was evaluated for horizontal unevenness generated during peeling. Further, the residual solvent amount and the film thickness of the web at the time of peeling and the film at the time of finishing were measured. The results are shown in Table 2.

[0087]

[Table 1]

[0088]

[Table 2]

(Results) As is clear from Table 2, according to the method for producing a cellulose ester film of the present invention, the adhesion between the web and the belt can be reduced, so that a film having good surface quality without horizontal unevenness can be obtained. Is obtained.
On the other hand, those containing no alcohol and having a dope temperature lower than the belt temperature had a large adhesive force and a strong horizontal step. In addition, in the case of containing a very large amount of alcohol, a large amount of undissolved substances could not be formed.

[0090]

According to the present invention, even when a cellulose ester solution not using a chlorine-based organic solvent is used, the adhesion between the film and the support can be reduced. This makes it possible to provide a method for producing a cellulose ester film having good surface quality without horizontal unevenness and a film for a liquid crystal image display device.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA09 AA81 AC02 AC05 AC09 AC10 AE19 AH12 BB02 BC01 4J002 AB02W DE028 EC036 EF039 EH036 EH147 HA05

Claims (13)

[Claims] 1. A method for producing a cellulose ester film by a solution casting film forming method using a cellulose ester having an acyl group having 2 to 4 carbon atoms as a substituent, wherein X is the degree of acetyl group substitution, When the degree of substitution of the group and / or butyryl group is Y, a cellulose ester satisfying the following formulas (I) and (II) at the same time is converted from an alcohol selected from those having 1 to 4 carbon atoms with respect to the total organic solvent. A method for producing a cellulose ester film, comprising dissolving in a non-chlorine-based organic solvent containing 0.1 to 30% by weight to form a dope, and forming a film using the dope. (I) 2.6 ≦ X + Y ≦ 3.0 (II) 0 ≦ X ≦ 2.5 2. A method for producing a cellulose ester film by a solution casting film-forming method using a cellulose ester having an acyl group having 2 to 4 carbon atoms as a substituent, wherein X is the degree of acetyl group substitution, When the substitution degree of the group and / or butyryl group is Y, a cellulose ester satisfying the following formulas (III) and (IV) at the same time is converted from an alcohol selected from those having 1 to 4 carbon atoms with respect to the total organic solvent. A method for producing a cellulose ester film, comprising dissolving in a non-chlorine-based organic solvent containing 1% by weight or more and less than 10% by weight to form a dope, and forming a film using the dope. (III) 2.6 ≦ X + Y ≦ 3.0 (IV) 2.5 <X ≦ 3.0 3. The method for producing a cellulose ester film according to claim 1, wherein the dope contains 1 to 10% by weight of the alkyl phthalyl alkyl glycolate based on the cellulose ester. 4. The temperature range of the entire surface of the casting support in the solution casting film forming method is 10 to 60 ° C., and the temperature of the dope is
The cellulose ester film according to any one of claims 1 to 3, wherein the casting is performed on the casting support at a temperature equal to or higher than the temperature at the dope casting position of the casting support. Production method. 5. Casting a cellulose ester dope on a casting support to form a web, setting the casting support temperature at a web peeling position on the casting support to 10 to 40 ° C., and The residual solvent amount of the web at the peeling position is 20
The method for producing a cellulose ester film according to any one of claims 1 to 4, wherein the web is peeled at a time when the content is adjusted to 100% by weight. 6. The method for producing a cellulose ester film according to claim 1, wherein the dope contains 0.5 to 5% by weight of water based on the cellulose ester. 7. The method for producing a cellulose ester film according to claim 1, wherein the dope contains 0.1 to 2% by weight of acetic acid with respect to the cellulose ester. 8. A cellulose ester having a molecular weight of 70,000 to 30,000.
The method for producing a cellulose ester film according to any one of claims 1 to 7, having a number average molecular weight of 0000. 9. The method for producing a cellulose ester film according to claim 1, wherein Y is a degree of substitution of a propionyl group. 10. The method for producing a cellulose ester film according to claim 1, wherein the non-chlorine organic solvent is methyl acetate. 11. The method for producing a cellulose ester film according to claim 1, wherein the alcohol is ethanol. 12. The dope contains 10 to 40% by weight of a cellulose ester.
The method for producing a cellulose ester film according to any one of claims 1 to 10. 13. A cellulose ester film produced by the method according to claim 1. Description: