JPH11292988A - Production of cellulose acylate and cellulose acylate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cellulose acylate film capable of reducing the use of a chlorine-based hydrocarbon such as methylene chlorine or not using it at all and to obtain a cellulose acylate film having excellent physical properties and surface qualities produced by this method. SOLUTION: This method for producing a cellulose acylate film comprises using a solution obtained by a process for adding a cellulose acylate containing a hydroxyl group substituted with a 2-5C acyl group to an organic solvent containing 60-95 wt.% of at least one selected from methyl acetate, cyclohexanone and ethyl formate and 5-40 wt.% of acetone to give a mixture and cooling the mixture to -100 to -10 deg.C and a process for heating the mixture to 0-50 deg.C after the cooling and forming a film from the solution by solution casting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cellulose acylate film useful for a silver halide photographic material or a liquid crystal image display device, and a cellulose acylate film produced by the method.

[0002]

2. Description of the Related Art Conventionally, an organic solvent of a cellulose triacetate solution used for producing a cellulose triacetate film used for a silver halide photographic material or a liquid crystal image display device includes a chlorine-based organic solvent such as methylene chloride. Hydrocarbons are used. Methylene chloride (boiling point: 41 ° C.) has been conventionally used as a good solvent for cellulose triacetate, and is preferably used because it has a low boiling point in the film forming and drying steps of the manufacturing process, and is easily dried. However, the use of chlorine-based compounds has recently been restricted, and the invention of a method for producing a cellulose triacetate film that does not use methylene chloride or can greatly reduce it has been awaited. Conventionally known solvents which exhibit solubility in cellulose triacetate other than methylene chloride include acetone (boiling point: 56 ° C.) and methyl acetate (boiling point: 56.degree. C.).
3 ° C.), tetrahydrofuran (boiling point 65.4 ° C.), 1,
Examples include 3-dioxolane (boiling point 75 ° C.), nitromethane (boiling point 101 ° C.), 1,4-dioxane (boiling point 101 ° C.), epichlorohydrin (boiling point 116 ° C.), N-methylpyrrolidone (boiling point 202 ° C.), and the like. When these organic solvents were actually subjected to a dissolution test, some of them were not necessarily good solvents, and there were almost no such solvents that could be put to practical use, such as those having a risk of explosion and those having a high boiling point.

[0003] Among the above-mentioned solvents, acetone having a low boiling point only swells cellulose triacetate by an ordinary method but does not dissolve it. In recent years, attempts have been made to dissolve cellulose triacetate in acetone to produce fibers and films.

[0004] M. G. FIG. Cowie et al., Die M
akromolekulare Chemie, 143
Vol. 105-114 (1971), the mixture of cellulose triacetate (acetylation degree 60.1-61.3%) was cooled to -80 to -70 ° C in acetone, and then heated to 0. A dilute solution of 5-5% by weight is reported to have been obtained. Such a method of melting at a low temperature is called a cooling melting method. In addition, Kenji Ude et al. Described spinning using a cooling dissolution method in "Dry spinning of cellulose triacetate from an acetone solution" in Journal of the Textile Machinery Society, Vol. 34, No. 7, pp. 57-61 (1981). Talk about technology.

JP-A-9-95544 and JP-A-9-955
No. 57, in the background of the above-mentioned technology, dissolving cellulose triacetate by a cooling dissolution method using an organic solvent substantially consisting of acetone, or using acetone and another organic solvent, and applying the method to film production. is suggesting.

However, a film formed from a cellulose triacetate solution using an acetone solvent obtained by the above method is inferior in flatness, has a high film haze of 1 to 2.1%, and has a large fluctuation. There's a problem.

Japanese Patent Application Laid-Open No. 9-95538 discloses a film prepared by using a solution obtained by dissolving cellulose triacetate by a cooling dissolution method using an organic solvent selected from ethers, ketones or esters other than acetone. These organic solvents are preferably 2-methoxyethyl acetate, cyclohexanone, ethyl formate, methyl acetate, and the like.

[0008] However, the film formed from the cellulose triacetate solution obtained by the above method also has a problem that the flatness is poor.

In addition, the viscosity of a cellulose acylate solution obtained by the cooling dissolution method is not adjusted well, and the viscosity is high when the solution is fed through a pipe for film formation, and high pressure is required. However, cellulose acylate did not work because of the difficulty of the above.

Japanese Patent Application Laid-Open No. 10-45804 proposes a mixed fatty acid ester of cellulose having an acetyl group and an acyl group having 3 or more carbon atoms, which is soluble in a solvent such as acetone or methyl acetate. According to the invention,
It is said that physical properties equivalent to or higher than cellulose triacetate can be obtained. Japanese Patent Application Laid-Open No. H10-60170 discloses that a cellulose mixed fatty acid ester has 3 to 12 carbon atoms.
A first organic solvent selected from ketones, esters and ethers and a second organic solvent selected from alcohols having 3 to 8 carbon atoms
Discloses a method for preparing a cellulose ester solution by dissolving in a solution containing an organic solvent to form a film.

[0011]

A compound having a high degree of substitution of an acyl group other than an acetyl group has insufficient physical properties, and in practice, only a compound having a small degree of substitution of an acyl group can be used practically. Was. When the substitution degree of the acyl group is high, it is not necessary to use a special dissolution method such as a cooling dissolution method,
In the case where the degree of substitution of the acyl group is small, it is necessary to dissolve the acyl group by a cooling dissolution method.

The above-mentioned problems of poor film flatness and high and fluctuating film haze are considered to be mainly due to the following reasons.

In general, a cellulose triacetate film is produced by casting a cellulose triacetate solution from a die onto a support running endlessly, and then stripping the support from the support and evaporating the solvent from the web. However, if the viscosity of the solution to be cast is too high, the leveling on the support is insufficient, or if it is severe, shark skin is generated, resulting in a film having poor flatness.
Usually, in order to obtain a cellulose triacetate film having good flatness, the viscosity of a methanol solution of cellulose triacetate in methylene chloride / methanol is adjusted to 0.5 Pa · s
A preferable range is from 5 (5 poise) to 50 Pa · s (500 poise). The viscosity of the cellulose triacetate solution obtained by the above cooling dissolution method is 240 Pa · s when acetone is used as a solvent, and 90 Pa · s when methyl acetate is used as a solvent. Degradation was a problem.

Further, in the above-mentioned method, the transparency and stability of the prepared cellulose triacetate solution are poor unless the low polymerization degree portion of the cellulose triacetate is removed beforehand. The film haze was high and the fluctuation was large.

As a method of reducing the viscosity of the solution, a method of lowering the concentration of cellulose triacetate in the solution can be considered. However, since the time required for evaporating the solvent is lengthened and the productivity is remarkably reduced, it is adopted. Difficult to do. Also,
Although it is conceivable to use cellulose triacetate having a low viscosity-average degree of polymerization, there is a problem that the mechanical strength (such as tear strength) of the obtained film is significantly reduced. Further, when the solution temperature is increased, there is a problem that the stability of the solution is deteriorated and phase separation occurs.

As described above, a cellulose triacetate film formed by a solution prepared by a cooling dissolution method using a solvent such as acetone or methyl acetate has poor flatness, high film haze, and fluctuation. However, there is a problem that such a material cannot be put to practical use as it is, particularly for a silver halide photographic light-sensitive material and a liquid crystal image display device, which require high quality of flatness and transparency.

Accordingly, an object of the present invention is to produce a cellulose acylate film which does not have the above-mentioned quality problems and which can greatly reduce the use of chlorinated hydrocarbons such as methylene chloride, or does not use it. An object of the present invention is to provide a method and a cellulose acylate film produced by the method and having excellent physical properties and surface quality.

[0018]

Means for Solving the Problems The present inventors have diligently prepared a cellulose acylate solution and a method for forming a cellulose acylate film in which the amount of use of the chlorinated hydrocarbon is reduced or not used at all. As a result of examination, even in cellulose acylate in which an acetyl group and another acyl group are substituted as an acyl group, or in cellulose triacetate in which only an acetyl group is substituted,
By using a specific mixed organic solvent, it was found that a cellulose triacetate solution can be easily prepared, and a method for obtaining a cellulose triacetate film having excellent mechanical properties formed using the same was also found. .

The above object of the present invention has been achieved by the following constitutions.

(1) In an organic solvent containing at least one selected from methyl acetate, cyclohexanone and ethyl formate in an amount of 60 to 95% by weight and acetone in an amount of 5 to 40% by weight,
A mixture obtained by adding a cellulose acylate in which a hydroxyl group is substituted with an acyl group having 2 to 5 carbon atoms is -100 to
Cooling to −10 ° C. and after cooling the mixture
A method for producing a cellulose acylate film, wherein solution casting is performed using a solution prepared through a step of heating to a temperature of ° C.

(2) In an organic solvent containing at least one selected from methyl acetate, cyclohexanone and ethyl formate in an amount of 60 to 95% by weight and acetone in an amount of 5 to 40% by weight,
A mixture obtained by adding a cellulose acylate in which a hydroxyl group is substituted by an acyl group having 2 to 5 carbon atoms is prepared by mixing 50 to 40.
Step of holding the 00kgf / cm ^2, and after pressurization the mixture using a solution prepared through the step of holding the 0.1 to 10 / cm ^2, the cellulose which is characterized in that the solution casting film A method for producing an acylate film.

(3) The organic solvent according to (1) or (2), which is an organic solvent containing 65 to 75% by weight selected from methyl acetate, cyclohexanone and ethyl formate and 25 to 35% by weight of acetone. A method for producing the cellulose acylate film according to the above.

(4) An additive is added in any step of preparing the cellulose acylate solution, or a step of adding an additive is provided after the step (1) to (3). The method for producing a cellulose acylate film according to any one of the above.

(5) The production of a cellulose acylate film according to any one of (1) to (4), wherein the cellulose acylate satisfies all of the following formulas (I) to (IV). Method.

(I) 2.6 ≦ A + B ≦ 3.0 (II) 2.0 ≦ A ≦ 3.0 (III) 0 ≦ B ≦ 0.8 (IV) 1.9 <AB In the formula, A and B represent the degree of substitution of an acyl group substituted by a hydroxyl group of cellulose, and A represents an acetyl group;
B is the degree of substitution of an acyl group having 3 to 5 carbon atoms.

(6) The method for producing a cellulose acylate film according to (5), wherein B is in the range of the following formula (V).

(V) 0 <B ≦ 0.3 (7) The viscosity average degree of polymerization of the cellulose acylate is 200
The method for producing a cellulose acylate film according to any one of (1) to (5), wherein the number is 700 or less.

(8) The viscosity average degree of polymerization is from 250 to 5
(7) The method for producing a cellulose acylate film as described in (7) above.

(9) The method according to any one of (1) to (8), wherein the concentration of the cellulose acylate in the cellulose acylate solution is from 15% by weight to 35% by weight. A method for producing a cellulose acylate film.

(10) The cellulose acylate film according to (4), wherein the additive is a plasticizer, and the plasticizer is added in an amount of 5% by weight or more and 30% by weight or less based on the cellulose acylate. Production method.

(11) A cellulose acylate film produced by the method according to any one of (1) to (10).

The present invention will be described in detail.

In the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group satisfies all of the following formulas (I) to (IV).

(I) 2.6 ≦ A + B ≦ 3.0 (II) 2.0 ≦ A ≦ 3.0 (III) 0 ≦ B ≦ 0.8 (IV) 1.9 <AB In the formula, A and B each represent a substituent of an acyl group substituted by a hydroxyl group of cellulose, A represents a degree of substitution of an acetyl group, and B represents a degree of substitution of an acyl group having 3 to 5 carbon atoms. Cellulose has three hydroxyl groups in one glucose unit, and the above numbers indicate the degree of substitution for the hydroxyl group 3.0, with the maximum degree of substitution being 3.0. Cellulose triacetate generally has a substitution degree of A of 2.6 or more and 3.0.
(In this case, there is a maximum of 0.4 unsubstituted hydroxyl groups), and the case where B = 0 is cellulose triacetate. The cellulose acylate of the present invention is a cellulose triacetate in which the acyl groups are all acetyl groups, and the acetyl groups are 2.0 or more, the acyl groups having 3 to 5 carbon atoms are 0.8 or less, and the unsubstituted hydroxyl groups are 0.4
The following are preferred. In the case of an acyl group having 3 to 5 carbon atoms, 0.3 or less is particularly preferable from the viewpoint of physical properties.

The degree of substitution can be obtained by measuring the degree of binding between acetic acid and a fatty acid having 3 to 5 carbon atoms that substitute for the hydroxyl group of cellulose, and calculating the degree of substitution. As a measuring method, A
It can be carried out according to STM D-817-91.

The polymerization degree (average viscosity) of the cellulose acylate used in the present invention is preferably from 200 to 700, particularly preferably from 250 to 550. Cellulose acylate film generally containing cellulose triacetate,
In order for the mechanical strength of the fiber or molded article to be tough, the degree of polymerization is required to be 200 or more. For example, Hiroshi Sobue and Nobuhiko Mita, "Cellulose Handbook," Asakura Shobo (1958), Hiroshi Marusawa, It is described in Kazuo Uda, “Plastic Materials Course 17”, Nikkan Kogyo Shimbun (1970). The polymerization degree of the cellulose acylate film of the invention is particularly preferably from 250 to 350. The viscosity average degree of polymerization can be measured by an Ostwald viscometer, and is determined by the following equation from the measured intrinsic viscosity [η] of cellulose acylate.

DP = [η] / Km (where DP is the viscosity-average degree of polymerization and Km is a constant of 6 × 10 ⁻⁴ ) Examples of the cellulose as a raw material of the cellulose acylate used in the present invention include cotton linter and wood pulp. However, cellulose acylate obtained from any of the starting celluloses may be used, or may be used as a mixture.

The cellulose triacetate used in the present invention is preferably of photographic grade, and commercially available photographic grades can be obtained with satisfactory qualities such as viscosity average polymerization degree and acetylation degree. Manufacturers of photographic grade cellulose triacetate include Daicel Chemical Industries, Ltd., Coatles, Hoechst, Eastman Kodak and the like, and any photographic grade cellulose triacetate can be used.

The cellulose acylate having an acetyl group and an acyl group having 3 to 5 carbon atoms used in the present invention is also called a mixed fatty acid ester of cellulose. Other acyl group having 3 to 5 carbon atoms an acetyl group is a propionyl group (C ₂ H ₅ CO-), butyryl group (C ₃ H ₇ CO-)
(N-, iso-), valeryl _{(C 4 H 9 CO -)} (n
-, Iso-, sec- and tert-), of which n-substituted ones are preferred from the viewpoint of mechanical strength and ease of dissolution when formed into a film, and particularly preferred is an n-propionyl group.

On the other hand, if the degree of substitution of the acetyl group is low, the mechanical strength and the moist heat resistance decrease. If the degree of substitution of the acyl group having 3 to 5 carbon atoms is high, the solubility in a mixed solution of methyl acetate and acetone is improved, but if the degree of substitution is within the above range, good physical properties are exhibited.

The acylating agents for these acyl groups include:
In the case of an acid anhydride or an acid chloride, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent. As the catalyst, a protic catalyst such as sulfuric acid is preferably used. When the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), a basic compound is used. The most common industrial method is to convert cellulose into fatty acids (acetic acid, propionic acid, butyric acid, valeric acid) or their anhydrides (acetic anhydride, propionic anhydride, butyric anhydride) corresponding to acetyl and other acyl groups. , Valeric anhydride) to synthesize cellulose acylate.

The specific method for producing the cellulose acylate used in the present invention is described in, for example,
It can be synthesized by the method described in No. 45804.

Next, a solvent for dissolving the cellulose acylate of the present invention and a dissolution method will be described.

The total amount of the organic solvent in the present invention is defined as methyl acetate,
It means the total weight of at least one solvent selected from cyclohexanone and ethyl formate and acetone.

The organic solvent used in the present invention is at least one selected from the group consisting of methyl acetate, cyclohexanone and ethyl formate, and swells cellulose acylate at room temperature. Further, in the present invention is characterized by coexisting acetone in addition to these solvents,
At least one solvent selected from methyl acetate, cyclohexanone and ethyl formate is 60 to 95% by weight, acetone is 5 to 40% by weight,
Preferably, the former is 65 to 75% by weight and the latter is 25 to 75% by weight.
35% by weight. By setting this ratio, not only the solubility, but also the castability at the time of casting the cellulose acylate solution (hereinafter sometimes referred to as dope) on the support,
In addition, the flatness of the film can be improved. Two or more of the former solvents may be used in combination. Among them, a combination of methyl acetate and acetone is most preferable, and a film having good solubility and excellent transparency can be obtained.

The dope used in the present invention may contain, in addition to the above-mentioned organic solvent of the present invention, a fluoroalcohol or methylene chloride of 10% by weight or less of the total amount of the organic solvent of the present invention to improve the transparency of the film. It is preferable in terms of accelerating the solubility. As the fluoroalcohol, those having a boiling point of 165 ° C. or less are preferable, and 111 ° C. is preferable.
Or less, more preferably 80 ° C. or less. The fluoroalcohol has about 2 to 10 carbon atoms, preferably about 2 to 8 carbon atoms. The fluoroalcohol is a fluorine atom-containing aliphatic alcohol which may or may not have a substituent. As the substituent, an aliphatic substituent with or without a fluorine atom, an aromatic substituent and the like are preferable. Such fluoroalcohols are, for example, (boiling points in parentheses below) 2-fluoroethanol (103 ° C), 2,2,2-trifluoroethanol (80 ° C), 2,2,3,3-tetrafluoro -1-propanol (109 ° C), 1,3
-Difluoro-2-propanol (55 ° C), 1,1,
1,3,3,3-hex-2-methyl-2-propanol (62 ° C), 1,1,1,3,3,3-hexafluoro-2-propanol (59 ° C), 2,2,3 , 3,3
-Pentafluoro-1-propanol (80 ° C.), 2,
2,3,4,4,4-hexafluoro-1-butanol (114 ° C.), 2,2,3,3,4,4,4-heptafluoro-1-butanol (97 ° C.), perfluoro-t
ert-butanol (45 ° C), 2,2,3,3,4
4,5,5-Octofluoro-1-pentanol (14
2 ° C), 2,2,3,3,4,4-hexafluoro-
1,5-pentanediol (111.5 ° C), 3,3
4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol (95 ° C), 2,2,2
3,3,4,4,5,5,6,6,7,7,8,8,8
-Pentadecafluoro-1-octanol (165
C), 1- (pentafluorophenyl) ethanol (8
2 ° C.), 2,3,4,5,6-pentafluorobenzyl alcohol (115 ° C.), and the like. One or more of these fluoroalcohols may be used.

The dope of the present invention may contain a lower alcohol having 1 to 6 carbon atoms. For example, methanol, ethanol, propanol, iso-propanol, n-butanol, sec-butanol, tert-
Butanol, cyclohexanol and the like. Among them, methanol, ethanol and n-butanol are preferred. The content is 2 to the total amount of the organic solvent of the present invention.
It is preferably 0% by weight or less. As described above, the cellulose acylate solution containing a lower alcohol having 1 to 6 carbon atoms has a high film strength even in a state where a large amount of the residual solvent is contained when casting and casting. It is easy to peel off.

The method for preparing the dope of the present invention will be described.

The dissolution of the cellulose acylate of the present invention
This can be achieved by a cooling melting method or a high pressure melting method.

First, in the cooling dissolution method of the present invention, a combination of the organic solvent of the present invention with acetone and at least one selected from methyl acetate, ethyl formate and cyclohexane, and the addition of fluoroalcohol to the organic solvent of the present invention. The cellulose acylate of the present invention is gradually added with stirring at room temperature to the organic solvent of the present invention to which a third organic solvent such as an alcohol having 1 to 6 carbon atoms is added. In this method, the mixture is swollen in an organic solvent, and then the mixture is cooled and then heated to dissolve. The cooling temperature may be a temperature equal to or higher than the freezing point of the solvent, and is preferably in the range of -100 to -10C from the viewpoint of solubility and easy handling. When this cooled product is heated to a temperature of 0 to 50 ° C., the cellulose acylate dissolves in the solvent to obtain a uniform solution. In addition, in order to accelerate dissolution, the operation of cooling and heating may be repeated. Whether or not the dissolution is sufficient can be determined by visually observing the appearance of the solution. In the cooling dissolution method, it is preferable to use a closed container in order to avoid mixing of water due to condensation during cooling. In the cooling operation, when the pressure is increased during cooling and the pressure is decreased during heating, the dissolution time can be further reduced. In order to perform pressurization and decompression, it is preferable to use a pressure-resistant container.

Another dissolution method of the present invention is a high-pressure dissolution method. In the organic solvent or the like of the present invention, cellulose acylate is added and mixed, and this mixture is kept under a high pressure, and then the pressure is released, and the dope is prepared by keeping the mixture near normal pressure. Things.

Until this mixture is obtained, it can be carried out in the same manner as in the cooling dissolution method described above. First, cellulose acylate at room temperature in an organic solvent of the present invention such as methyl acetate, in acetone, in an all organic solvent of the present invention, or in an organic solvent containing a third solvent such as fluoroalcohol. Is added slowly with stirring. At this stage, the cellulose acylate is in a state of being swollen in the solvent. next,
This mixture is kept under high pressure. The pressure is 50kg
The effect is recognized from f / cm ² or more, and the dissolution time can be shortened as the value is higher, but if it is too high, the equipment becomes too large, and the effect of shortening the dissolution time gradually becomes saturated.
If it is 4000 kgf / cm ² or less, a sufficient effect can be obtained. After pressurizing for a predetermined time, the pressure is released, and the mixture is kept under a pressure of 0.1 to 10 kgf / cm ² or less, whereby the cellulose acylate is dissolved in the solvent to obtain a uniform solution. In addition, in order to accelerate dissolution, the operations of pressurization and pressure release may be repeated. Whether or not the dissolution is sufficient can be determined by visually observing the appearance of the solution. There is no particular limitation on the container to be dissolved, and any structure may be used as long as it has a strength to withstand pressure. It may be performed batchwise using a sealed container made of aluminum foil or the like, or may be continuously performed using a single-screw or twin-screw extruder, kneader, or the like. Also, cooling in the pressurizing operation,
Heating in the release operation can further reduce the dissolution time. The cellulose acylate concentration in the solution is
From the viewpoint of drying efficiency at the time of film formation, the concentration is preferably as high as possible. On the other hand, if the concentration is too high, the viscosity of the solution may be too large, and the planarity may deteriorate. Therefore, a preferred solution has a cellulose acylate concentration of 1
It is in the range of 0 to 40% by weight. Further, a range of 15 to 35% by weight is preferable.

The container may be filled with an inert gas such as nitrogen gas to suppress decomposition. The viscosity of the cellulose acylate solution may be within a range that can be cast at the time of film formation, and is preferably adjusted to a range of usually 5 to 500 poise.

In the present invention, the concentration of cellulose acylate in the solution may be in the range of 10 to 40% by weight in the cooling dissolution or high pressure dissolution step. A preferred method is to evaporate the solvent immediately before casting the solution during film formation to prepare a high-concentration solution. The concentration of cellulose acylate in the low concentration solution is preferably less than 1 to 10% by weight, and the concentration of cellulose acylate in the high concentration solution is preferably in the range of 10 to 40% by weight, more preferably 15 to 35% by weight.
The following is preferred. There is no particular limitation on the concentration method. To obtain a high-concentration solution while evaporating the solvent (for example,
No. 9511), a heated low-concentration solution is blown into a container from a nozzle, and the solvent is flash-evaporated until the solution hits the inner wall of the container from the nozzle. (For example, US Pat. Nos. 2,541,012, 2,858,229, 4,414,341, and 4,504,355), and the like.

As described above, the stability of the dope over time can be improved by dissolving it at a low concentration by cooling or dissolving it under a high pressure. Further, since a low concentration solution has a low viscosity, undissolved substances, dust, impurities, etc. Such foreign substances can be efficiently removed by filtration.

The cellulose acylate solution of the present invention can contain various additives depending on the use in each preparation step. The doping may be added at any time during the dope preparation step, but may be performed by adding a step of adding and preparing an additive to the last preparation step of the dope preparation step. Cellulose acylate films for silver halide photographic materials contain a plasticizer or a colorant for preventing light piping or an ultraviolet light inhibitor for improving mechanical properties or imparting water resistance, and for a liquid crystal display device. It is preferable to add an antioxidant or the like that imparts heat and moisture resistance.

As the plasticizer, phosphoric acid esters, carboxylic acid esters, glycolic acid esters and the like are preferably used. Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.Examples of carboxylate esters include dimethyl phthalate. ,
There are diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethylhexyl phthalate, acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, trimellitate, and the like. Examples include triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate and the like. Among them, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate,
Diethylhexyl phthalate, triacetin, ethylphthalylethyl glycolate are preferred. Particularly, triphenyl phosphate, diethyl phthalate, and ethyl phthalyl ethyl glycolate are preferred. These plasticizers may be used alone or in combination of two or more. The added amount of the plasticizer is preferably 5 to 30% by weight or less, particularly preferably 8 to 16% by weight or less based on the cellulose acylate. These compounds are
When preparing the cellulose acylate solution, it may be added together with the cellulose acylate or the solvent, or may be added during or after the solution preparation.

Further, the following general formulas (I), (II) and (III)
May be added.

[0059]

Embedded image

In the formulas (I), (II) and (III),
R is an alkyl group having 1 to 4 carbon atoms. Examples of the compound represented by the above general formula (I), (II) or (III) include sodium 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate (ADEKA STAB NA-10, Asahi Denka Co., Ltd.) and bis (p-ethylbenzylidene) sorbitol (NC-
4, Mitsui Toatsu Chemical Co., Ltd.).

As the antioxidant, those represented by the following general formula (IV) are used.

[0062]

Embedded image

R _{1 in the} general formula (IV) represents an alkyl group,
R ₂ , R ₃ and X each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group,
Alkenoxy group, aryloxy group, alkylthio group,
Represents an alkenylthio group, an arylthio group, a heterocyclic oxy group, a hydroxy group, an amino group, a carbamoyl group, a sulfamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a halogen atom, a nitro group, a cyano group, an acyl group, and an acyloxy group. m represents an integer of 0 to 2. R ₂ , R ₃ and X may be the same or different. The alkyl group is, for example, methyl, ethyl, propyl, iso-propyl, tert-butyl,
Represents a linear, branched or cyclic alkyl group such as cyclohexyl, tert-hexyl, tert-octyl, dodecyl, hexadecyl, octadecyl, benzyl, and the alkenyl group is, for example, vinyl, allyl, 2-pentenyl, cyclohexenyl, Hexenyl, dodecenyl,
Represents a straight-chain, branched, or cyclic alkenyl group such as octadecenyl; the aryl group includes, for example, a benzene monocyclic or condensed polycyclic aryl group such as phenyl, naphthyl, and anthranyl; and the heterocyclic group includes, for example, , Furyl, pyrrolyl, imidazolyl, pyridyl, purinyl, chromanyl, pyrrolidyl, morpholinyl and other nitrogen atoms,
Represents a group comprising a 5- to 7-membered ring containing at least one of a sulfur atom and an oxygen atom. Among them, hindered phenol compounds are preferable, and 2,6-di-tert-butyl-p-
Cresol, pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6- Hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,
4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,
3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3 , 5-trimethyl-2,
4,6-tris (3,5-di-tert-butyl-4-
(Hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Especially 2,6-di-te
rt-butyl-p-cresol, pentaerythrityl-
Tetrakis [3- (3,5-di-tert-butyl-4
-Hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5)
-Methyl-4-hydroxyphenyl) propionate]
Is most preferred. Further, for example, N, N'-bis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine-based metal deactivators such as hydrazine and phosphorus-based processing stability such as tris (2,4-di-tert-butylphenyl) phosphite Agents may be used in combination. The addition amount of these compounds is preferably 1 ppm to 1.0% by weight, and more preferably 10 to 1000 ppm, based on the weight of the cellulose acylate.

Examples of the coloring agent for preventing light piping include compounds represented by the following formulas (V) and (VI).

[0065]

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[0066] wherein, X represents an oxygen atom of the general formula (V), (VI), or represents NR _23. R _{1 to} R ₈ and R _{12 to} R ₂₃ each represent a hydrogen atom, a hydroxyl group, an aliphatic group, an aromatic group, a heterocyclic group, a halogen atom, a cyano group, a nitro group, COR ₉ , C ₉
OOR ₉ , NR ₉ R ₁₀ , NR ₁₀ COR ₁₁ , NR ₁₀ SO ₂ R
₁₁ , CONR ₉ R ₁₀ , SO ₂ NR ₉ R ₁₀ , COR ₁₁ , SO ₂
R ₁₁ , OCOR ₁₁ , NR ₉ CONR ₁₀ R ₁₁ , CONHS
O ₂ R ₁₁ or SO ₂ NHCOR ₁₁ , R ₉ and R ₁₀ each represent a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group, and R ₁₁ represents an aliphatic group, an aromatic group, or a heterocyclic group; Represents a ring group.

The aliphatic group represented by R _{1 to} R ₂₃ is an alkyl group having 1 to 20 carbon atoms (eg, methyl, ethyl, n-
Butyl, isopropyl, 2-ethylhexyl, n-decyl, n-octadecyl), a cycloalkyl group having 1 to 20 carbon atoms (eg, cyclobenzyl, cyclohexyl) or an allyl group, which further has a substituent (eg, a halogen atom) A hydroxyl group, a cyano group, a nitro group, a carboxylic acid group, an aryl group having 6 to 10 carbon atoms, an amino group having 0 to 20 carbon atoms, an amide group having 1 to 20 carbon atoms, a carbamoyl group having 1 to 20 carbon atoms, carbon An ester group having 2 to 20 carbon atoms, an alkoxy group or an aryloxy group having 1 to 20 carbon atoms, 1 carbon atom
It may have a sulfonamide group of 20 to 20, a sulfamoyl group of 0 to 20 carbon atoms, or a 5- or 6-membered heterocyclic ring. R
₁ aromatic group represented by to R ₂₃ is from 6 to 10 carbon atoms, phenyl, aryl groups such as naphthyl, the substituents and methyl having 1 to 20 carbon atoms mentioned above, ethyl, n- butyl, tert It may have a substituent consisting of an alkyl group such as -butyl and octyl. The heterocyclic group represented by R _{1 to} R ₁₁ represents a 5- or 6-membered heterocyclic ring, and may have the substituent described above. The following formulas (4) to (9)
Preferred examples of the compound represented by (VI): (V-1) to (V
-25), and (VI-1) to (VI-4).

[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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[0073]

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The content of the colorant is preferably from 10 to 1000 ppm by weight based on cellulose acylate.
The content is more preferably 50 to 500 ppm or less. By including a coloring agent in this manner, light piping of the cellulose acylate film can be reduced, and the yellow tint can be improved. These compounds may be added together with the cellulose acylate or the solvent when preparing the cellulose acylate solution, or may be added during or after the solution is prepared.

Further, if necessary, various additives may be added to the cellulose acylate solution of the present invention at any stage before or after the solution is prepared. Additives include ultraviolet absorbers, kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, inorganic fine particles such as alumina, heat stabilizers such as calcium and salts of alkaline earth metals such as magnesium, Antistatic agent,
Flame retardants, lubricants, oils and the like.

It is preferable that the solution be filtered to remove foreign matters such as undissolved matter, dust, and impurities by using a suitable filter medium such as a wire mesh or flannel before casting.

The dope of the present invention prepared as described above is an organic solvent comprising acetone, methyl acetate and the like described in JP-A-9-95538, JP-A-9-95544 and JP-A-9-95557. The viscosity is reduced compared to the dope prepared by the cooling dissolution method using
Good flatness of the obtained film is obtained. Further, the transparency and stability over time of the dope are excellent, and the haze of the film obtained therefrom is also good.

A method for producing a film using the cellulose acylate solution of the present invention will be described. As the method and equipment for producing the cellulose acylate film of the present invention, a solution casting method and a solution casting apparatus conventionally used for producing a cellulose triacetate film are used. The solution casting film forming method and apparatus will be described. The dope prepared by the above-mentioned preparation apparatus is sent to a pressurized die through a pressurized fixed quantity pump which can perform a high-precision fixed quantity liquid supply by, for example, the number of rotations, and pressurized from a precision gear pump. The dope fed into the die is uniformly cast from the die (slit) of the pressure die onto the support of the casting part running endlessly,
When the support has completed one round, the freshly dried dope film (also referred to as a web) is peeled from the support and conveyed through a group of rolls arranged in a zigzag pattern, or the web is held with clips at both ends to maintain the width of the web. The film is conveyed and dried while being conveyed, and the dried film is conveyed and wound up to a predetermined length by a winder.

As a casting method useful in the present invention, a method in which the prepared dope is uniformly extruded from a pressure die onto a support, and a film thickness of the dope once cast on the support is adjusted by a blade. There are a method using a doctor blade, a method using a reverse roll coater that adjusts with a roll that rotates in the reverse direction, and the like, but a method using a pressure die is preferable. The pressure die includes a coat hanger type and a T-die type, and any of them can be preferably used. In addition to the above-mentioned methods, various methods for casting a film of a cellulose triacetate solution known in the art (for example, see
JP-A-94724 and JP-A-61-148013;
No. 85011, No. 4-286611, No. 5-1854
No. 43, No. 5-185445, No. 6-278149
And the methods described in JP-A-8-207210) can be preferably used, and by setting each condition in consideration of the difference in the boiling point of the solvent to be used, the same effects as those described in the respective publications can be obtained. Is obtained.

As the support running endlessly used for producing the cellulose acylate film of the present invention, a drum whose surface is mirror-finished by chromium plating or a stainless steel belt (band and band) whose surface is mirror-finished by surface polishing is used. May be used).

The pressure die used for producing the cellulose acylate film of the invention may be one or two or more pressure dies above the support. Preferably it is one or two. When two or more dope units are installed, the amount of the dope to be cast may be divided into various ratios for each die, and the dope is sent to the die at each ratio from a plurality of precision metering gear pumps.

The drying of the dope on the support in the production of the cellulose acylate film of the present invention is generally carried out by removing hot air from the surface side of the support (drum or belt), that is, from the surface of the web on the support. Applying hot air from the back of the drum or belt, contacting the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heating the drum or belt by heat transfer to control the surface temperature Although there is a liquid heat transfer method, a back liquid heat transfer method is preferable.

The surface temperature of the support before casting may be any number as long as it is lower than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose the fluidity on the support, it is necessary to set the temperature to 1 to 10 ° C. lower than the boiling point of the solvent having the lowest boiling point among the solvents used. preferable.

The speed at which the cellulose acylate film is produced varies depending on the length of the belt, the drying method, the composition of the dope solvent, and the like, but is almost determined by the amount of the residual solvent at the time when the web is separated from the belt. That is,
If the solvent concentration in the vicinity of the belt surface in the thickness direction of the dope film is too high, the dope will remain on the belt when peeled, and it will hinder the next casting, so there is absolutely no peeling residue. This is because the web must have enough strength to withstand the peeling force. The amount of residual solvent at the time of peeling differs depending on the method of drying on the belt or drum, and the method of transferring heat from the back of the belt or drum is more effective than the method of drying by blowing air from the dope surface. Can be reduced.

As the film drying method for producing the cellulose acylate film of the present invention, the drying method of the above-mentioned solution casting method is preferable. Drying is performed by a method in which air at a predetermined temperature is applied to both surfaces of the web (film) being conveyed, or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the web (film), it is preferable to dry at a temperature at which the solvent does not foam at the initial stage of drying, and to dry at a high temperature after the drying proceeds.

In the drying step after peeling from the support, the film tends to shrink in the width direction due to evaporation of the solvent. The higher the temperature, the greater the shrinkage. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the resulting film. From this point,
For example, a method (tenter method) of drying the entire width of the web or a part of the web while holding both ends of the width of the web with clips in the width direction as shown in JP-A-62-46625 is preferable.

Further, there is also a method of positively stretching in the width direction. In the present invention, for example, JP-A-62-115035
And JP-A-4-152125 and JP-A-4-284221.
And the stretching methods described in JP-A Nos. 4-298310 and 4-298310 can also be used.

The drying temperature in the drying step of the cellulose acylate film of the present invention is from 40 to 250 ° C., especially 70 to 250 ° C.
~ 180 ° C is preferred. The drying temperature, the amount of drying air and the drying time vary depending on the solvent used.
What is necessary is just to select suitably according to a combination. The amount of the residual solvent in the final film is preferably 2% by weight or less, more preferably 0.4% by weight or less in order to obtain a film having good dimensional stability.

The steps from casting to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas.

The winding machine relating to the production of the cellulose acylate film of the present invention may be a generally used one, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with constant internal stress. Can be wound up.

The thickness of the finished (after drying) cellulose acylate film of the present invention varies depending on the purpose of use, but is usually in the range of 5 to 500 μm, and more preferably 40 to 500 μm.
A range of 250 μm is preferred, and a range of 60 to 125 μm is most preferred. The film thickness may be adjusted by adjusting the concentration of the solid content contained in the dope, the slit gap between the die caps, the extrusion pressure from the die, the speed of the support, and the like so as to obtain the desired thickness.

<Method of Measuring Degree of Substitution of Acyl Group and Degree of Viscosity Average Polymerization> 1) Degree of substitution of acyl group of cellulose acylate; Degree of substitution of acyl group shall be measured by a saponification method.
The dried cellulose acylate is precisely weighed, and acetone 70
After dissolving in a mixed solvent of 30 ml of dimethyl sulfoxide and 50 ml of dimethyl sulfoxide, 50 ml of acetone was further added. While stirring, 30 ml of a 1N aqueous solution of sodium hydroxide was added, and 25
Saponify at 0 ° C for 2 hours. 100 ml of hot water is added, phenolphthalein is added as an indicator, and excess sodium hydroxide is titrated with a 1N aqueous solution of sulfuric acid (concentration factor: F). A blank test is performed in the same manner as described above. The supernatant of the solution after completion of the titration was diluted to 100, and the composition of the organic acid was measured by a conventional method using ion chromatography. From the results of the titration and analysis of the acid composition by ion chromatography, the degree of acylation substitution was calculated as follows.

T [A + B] = (EM) × F / (100
0 × W) A = {162.14 × T [A + B]} / {1-42.1
4 × T [A + B] + (1-56.06 × T [A + B])
× (Cb / Ca)｝ B = A × (Cb / Ca) where, T [A + B]: total organic acid amount (mol / g) E: blank test titer (ml) M: sample titer (ml) F: Factor of 1N sulfuric acid W: Sample weight (g) Ca: Amount of acetic acid (mol) measured by ion chromatography Cb: Amount of organic acid having 3 to 5 carbon atoms (mol) measured by ion chromatography Cb / Ca: molar ratio between acetic acid and another organic acid A: degree of substitution of acetyl group B: degree of substitution of acyl group having 3 to 5 carbon atoms

2) Viscosity Average Polymerization Degree (DP) of Cellulose Acylate Approximately 0.2 g of absolutely dried cellulose acylate was precisely weighed, and a mixed solvent of methylene chloride and ethanol (weight ratio 9:
1) Dissolve in 100 ml. This is measured for drop seconds at 25 ° C. using an Ostwald viscometer, and the degree of polymerization is determined by the following equation.

Ηrel = T / Ts [η] = (lnηrel) / CDP = [η] / Km where T: falling seconds of the measurement sample Ts: falling seconds of the solvent C: concentration (g / l) Km: 6 × 10 ^-4

[0096]

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

The residual solvent amount of the film was measured as follows.

A test film or web (U) is placed in a weighing bottle and precisely weighed.
After heating at 0 ° C. for 3 hours, cool to room temperature so as not to absorb moisture and weigh. As the weight (D) of the absolutely dried film or web, the amount of residual solvent (%) = {(UD) / D} × 100.

For the dope in the examples, the transparency and stability with time and the viscosity of the dope, and for the film, the flatness, haze, tear strength, tensile strength, elastic modulus and bending resistance were measured and measured. The evaluation was performed by the following method.
Here, the film refers to a dried film cut out after winding in a winding step in the final stage of the cellulose acylate film manufacturing step.

<Transparency and Stability Over Time> The dope (cellulose acylate solution) was placed in a transparent container, and the transparency was observed visually immediately after preparation, after 72 hours and after 168 hours.
At the same time, the container was turned upside down to observe changes in the fluidity of the solution, and evaluated and ranked according to the following criteria.

A: Transparent and uniform dope, when the container was inverted, the dope moved smoothly. B: Slightly turbid, but transparent. When the container is turned upside down, there is fluidity, but a slightly squashed shape is observed at the moving interface. C: There is turbidity, insolubles are observed, and when the container is turned upside down, the dope moves unevenly. It is extremely turbid, contains many insolubles, is phase-separated, or has no fluidity even when the container is inverted, and is in a gel state.

<Viscosity> The viscosity was measured with a viscometer type B (manufactured by Tokimec Co.) while maintaining the dope temperature at 30 ° C.

<Flatness> Black paper was placed on a flat desk, a sample film of 100 cm × 40 cm was placed on it, and three fluorescent lamps arranged diagonally above were projected on the film to bend the fluorescent lamps. The flatness was evaluated according to the condition, and ranked according to the following criteria.

A: All three fluorescent lamps look straight B: Fluorescent lamp looks slightly bent C: Fluorescent lamp looks bent D: Fluorescent lamp looks large ridge

<Haze> The haze was measured using a haze meter (model 1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-6714.

<Tear Strength> The film was conditioned in a room conditioned at a temperature of 23 ° C. and a relative humidity of 55% RH for 4 hours.
Cut out sample size 50mm x 64mm, ISO-63
83 / 2-1983.

<Tensile strength and elastic modulus>
After humidifying for 4 hours in a room conditioned at 55 ° C. and a relative humidity of 55% RH, the sample was cut to a width of 10 mm and a length of 200 mm.
/ Min was determined by conducting a tensile test.

<Folding Resistance> The film was conditioned in a room conditioned at a temperature of 23 ° C. and a relative humidity of 55% RH for 4 hours, then cut into a sample length of 120 mm, and subjected to ISO-8776 / 2-.
According to 1988, the number of times of bending until cutting by bending was measured.

The number of times of bending before cutting by bending was measured.

Example 1 The degree of substitution of the acetyl group was 2.88 and the viscosity average degree of polymerization was 30.
0, 100 parts by weight of cellulose triacetate, 475 parts by weight of methyl acetate, 25 parts by weight of acetone, and 10 parts by weight of triphenyl phosphate (plasticizer) were mixed. At room temperature, the cellulose triacetate was in a swollen state. Next, the mixture was placed in a container having a double structure, and the mixture was slowly stirred and HFE-7100 (Sumitomo 3M Limited) controlled at -75 ° C as a refrigerant in the outer jacket.
Manufactured). This allows the mixture in the inner container to be -7
Cooled to 0 ° C. 30 until the mixture is uniformly cooled
Cooling continued for minutes.

Next, the refrigerant in the jacket outside the container was discharged, and instead, warm water was introduced into the jacket. Subsequently, the content was stirred, the temperature was raised to 30 ° C. over 40 minutes, and the stirring was continued for another 20 minutes.

This series of cooling and heating operations was repeated three times to obtain a transparent dope. The dope was allowed to stand at 30 ° C. overnight and subjected to a defoaming operation. After that, the dope was subjected to Azumi Filter Paper No. After filtration using 244, the mixture was subjected to film formation.

The obtained dope was fed to a die by a constant-quantity gear pump, and was cast on a stainless belt running endlessly so that the film thickness after drying was 120 μm. The first half was dried on a belt whose temperature was controlled by contacting warm water at 50 ° C. from the back surface, and the web was dried by blowing dry air at 90 ° C. in the second half. The web was peeled from the belt when the belt had made one round, and the web was dried at 120 ° C. for 5 minutes while holding both ends of the web with clips, and then dried at 140 ° C. for 20 minutes while being transported through a group of rolls. A cellulose triacetate film having a thickness of 120 μm was obtained. At each level, the residual solvent amount of the film was 0.9%.

Example 2 A film was prepared in the same manner as in Example 1 except that methyl acetate was changed to 400 parts by weight and acetone was changed to 100 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 3 A film having a film thickness of 12 was prepared in the same manner as in Example 1 except that methyl acetate was changed to 375 parts by weight and acetone was changed to 125 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 4 A film having a film thickness of 12% was prepared in the same manner as in Example 1 except that methyl acetate was changed to 350 parts by weight and acetone was changed to 150 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 5 A film having a film thickness of 12 was prepared in the same manner as in Example 1 except that methyl acetate was changed to 325 parts by weight and acetone was changed to 175 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 6 A film having a film thickness of 12% was prepared in the same manner as in Example 1 except that methyl acetate was changed to 300 parts by weight and acetone was changed to 200 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Comparative Example 1 A film was prepared in the same manner as in Example 1 except that methyl acetate was changed to 275 parts by weight and acetone was changed to 225 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Comparative Example 2 A film having a thickness of 120 μm was prepared in the same manner as in Example 1 except that methyl acetate was changed to 500 parts by weight and acetone was not added.
Was obtained as a cellulose triacetate film. The residual solvent amount of the obtained cellulose triacetate film was 0.1.
It was 9% by weight.

Comparative Example 3 A cellulose triacetate film having a thickness of 120 μm was obtained in the same manner as in Example 1 except that methyl acetate was not added and acetone was changed to 500 parts by weight. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Comparative Example 4 A cellulose triacetate film having a thickness of 120 μm was obtained in the same manner as in Example 1 except that methyl acetate was not added and acetone was changed to 400 parts by weight. The residual solvent amount of the obtained cellulose triacetate film was 0.5% by weight.

Example 7 A film was prepared in the same manner as in Example 3 except that methyl acetate was changed to 280 parts by weight and acetone was changed to 120 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.5% by weight.

Example 8 The substitution degree of the acetyl group of cellulose triacetate was set at 2.
76 and a viscosity average polymerization degree of 400 was obtained in the same manner as in Example 3 to obtain a cellulose triacetate film having a thickness of 120 µm. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 9 The degree of substitution of the acetyl group was 2.88 and the viscosity average polymerization degree was 30.
100 parts by weight of cellulose triacetate, 475 parts by weight of methyl acetate, 25 parts by weight of acetone, and 10 parts by weight of triphenyl phosphate. At room temperature, the cellulose triacetate was in a swollen state. Then, the pressure was gradually increased, and finally the pressure was set to 1000 kgf / cm ² .
After holding for 30 minutes as it was, the pressure was released, and the mixture was further held at normal pressure for 30 minutes. Thereafter, stirring was performed for 30 minutes to obtain a transparent dope. The dope was allowed to stand at 30 ° C. overnight, subjected to a defoaming operation, and, after that, the dope was subjected to Azumi Filter Paper N
o. After filtration using 244, the mixture was subjected to film formation. Using the obtained dope, a film was formed in the same manner as in Example 1, and the film thickness was 120 μm.
m of a cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 10 A film having a thickness of 120 μm was prepared in the same manner as in Example 9 except that methyl acetate was changed to 400 parts by weight and acetone was changed to 100 parts.
m of a cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 11 A film having a film thickness of 12% was prepared in the same manner as in Example 9 except that methyl acetate was changed to 350 parts by weight and acetone was changed to 150 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 12 A film was prepared in the same manner as in Example 9 except that methyl acetate was changed to 300 parts by weight and acetone was changed to 200 parts by weight.
A 0 μm cellulose triacetate film was obtained. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 13 The substitution degree of the acetyl group of cellulose triacetate was set at 2.
A cellulose triacetate film having a thickness of 120 μm was obtained in the same manner as in Example 11 except that the viscosity and the viscosity average degree of polymerization were changed to 400. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 14 The substitution degree of the acetyl group of cellulose triacetate was set at 2.
A cellulose triacetate film having a thickness of 120 μm was obtained in the same manner as in Example 11 except that the polymerization degree was changed to 92 and the viscosity average degree of polymerization was changed to 290. The residual solvent amount of the obtained cellulose triacetate film was 0.9% by weight.

Example 15 A cellulose acetate propionate having an acetyl group substitution degree of 2.71 and a propionyl group substitution degree of 0.17 and a viscosity average polymerization degree of 350 was used in place of cellulose triacetate. In the same manner as in Example 3, the film thickness 1
A 20 μm cellulose acetate propionate film was obtained. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 16 The film thickness was changed in the same manner as in Example 15 except that the substitution degree of the acetyl group was changed to 2.61, the substitution degree of the propionyl group was changed to 0.30, and the viscosity average polymerization degree was changed to 400. A 120 μm cellulose acetate propionate film was obtained.
The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 17 The film thickness was changed in the same manner as in Example 15 except that the substitution degree of the acetyl group was changed to 2.38, the substitution degree of the propionyl group was changed to 0.39, and the viscosity average polymerization degree was changed to 450. A 120 μm cellulose acetate propionate film was obtained.
The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 18 A cellulose acetate propionate having a degree of substitution of acetyl group of 2.71 and a degree of substitution of propionyl group of 0.17 and a viscosity average degree of polymerization of 350 was replaced with cellulose acetate propionate in place of cellulose triacetate. In the same manner as in Example 11, a cellulose acetate propionate film having a thickness of 120 μm was obtained. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 19 A cellulose acetate propionate having a degree of substitution of acetyl group of 2.61 and a degree of substitution of propionyl group of 0.3 and a viscosity average polymerization degree of 400 was used in place of cellulose triacetate. In the same manner as in Example 11, the film thickness 1
A 20 μm cellulose acetate propionate film was obtained. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 20 Cellulose acetate was replaced by cellulose triacetate instead of cellulose triacetate, in which the degree of substitution of acetyl group was 2.38, the degree of substitution of propionyl group was 039, and the viscosity average polymerization degree was 450. In the same manner as in Example 11, a cellulose acetate propionate film having a thickness of 120 μm was obtained. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 21 Example 1 was repeated except that methyl acetate was changed to cyclohexanone.
In the same manner as in 7, a cellulose acetate propionate film having a thickness of 120 μm was obtained. The residual solvent content of the obtained cellulose acetate propionate film was 0.1%.
It was 9% by weight.

Example 22 A cellulose acetate propionate film having a thickness of 120 μm was obtained in the same manner as in Example 17 except that methyl acetate was changed to ethyl formate. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Example 23 Example 2 was repeated except that methyl acetate was changed to cyclohexanone.
In the same manner as in Example No. 0, a cellulose acetate propionate film having a thickness of 120 μm was obtained. The residual solvent content of the obtained cellulose acetate propionate film was 0.1%.
It was 9% by weight.

Example 24 A cellulose acetate propionate film having a thickness of 120 μm was obtained in the same manner as in Example 20, except that methyl acetate was changed to ethyl formate. The residual solvent amount of the obtained cellulose acetate propionate film was 0.9% by weight.

Table 1 shows the evaluation results of the properties of the dopes and films of the examples and comparative examples.

[0142]

[Table 1]

(Results) As is clear from Table 1, the cellulose acylate solution (dope) prepared according to the present invention was obtained.
As compared with the dope prepared by the conventional cooling dissolution method shown in Comparative Examples 1 to 4, it was confirmed that the transparency and the posted stability of the dope were good and the viscosity of the dope was low. It was also found that the cellulose acylate film formed from the dope of the present invention had improved flatness and haze, and also had excellent mechanical strength.

[0144]

According to the present invention, a cellulose acylate solution which does not use a chlorine-based solvent at all or is used at all can be used for silver halide photographic materials and liquid crystal display devices having excellent flatness, transparency and mechanical strength. A cellulose acylate film to be used can be provided.

Claims (11)

[Claims] 1. An organic solvent containing 60 to 95% by weight of at least one selected from methyl acetate, cyclohexanone and ethyl formate and 5 to 40% by weight of acetone, wherein a hydroxyl group is an acyl group having 2 to 5 carbon atoms. A mixture obtained by adding the substituted cellulose acylate, -100 to-
Step of cooling to 10 ° C, and cooling the mixture to 0 to 50 ° C.
A method for producing a cellulose acylate film, comprising performing a solution casting film formation using a solution prepared through a step of heating the film. 2. An organic solvent containing 60 to 95% by weight of at least one selected from methyl acetate, cyclohexanone and ethyl formate and 5 to 40% by weight of acetone, wherein the hydroxyl group is an acyl group having 2 to 5 carbon atoms. The mixture obtained by adding the substituted cellulose acylate is mixed with 50 to 400
Step of holding the 0 kgf / cm ^2, and after pressurization the mixture using a solution prepared through the step of holding the 0.1 to 10 / cm ^2, the cellulose which is characterized in that the solution casting film A method for producing an acylate film. 3. The cellulose according to claim 1, which is an organic solvent containing 65 to 75% by weight selected from methyl acetate, cyclohexanone and ethyl formate and 25 to 35% by weight acetone. A method for producing an acylate film. 4. The method according to claim 1, wherein an additive is added in any step of preparing the cellulose acylate solution, or a step of adding an additive is provided after the step. 2. The method for producing a cellulose acylate film according to item 1. 5. The method for producing a cellulose acylate film according to claim 1, wherein the cellulose acylate satisfies all of the following formulas (I) to (IV). (I) 2.6 ≦ A + B ≦ 3.0 (II) 2.0 ≦ A ≦ 3.0 (III) 0 ≦ B ≦ 0.8 (IV) 1.9 <AB where A in the formula And B represent the degree of substitution of an acyl group substituted by a hydroxyl group of cellulose, and A represents an acetyl group;
B is the degree of substitution of an acyl group having 3 to 5 carbon atoms. 6. The method for producing a cellulose acylate film according to claim 5, wherein B is in the range of the following formula (V). (V) 0 <B ≦ 0.3 7. The method for producing a cellulose acylate film according to claim 1, wherein the viscosity average polymerization degree of the cellulose acylate is 200 or more and 700 or less. 8. The viscosity average degree of polymerization is from 250 to 500.
The method for producing a cellulose acylate film according to claim 7, wherein: 9. The cellulose acylate concentration in the cellulose acylate solution is 15% by weight or more and 35% by weight.
9. The method according to claim 1, wherein:
The method for producing a cellulose acylate film according to the above item. 10. The method for producing a cellulose acylate film according to claim 4, wherein the additive is a plasticizer, and the plasticizer is added in an amount of 5% by weight or more and 30% by weight or less based on the cellulose acylate. Method. 11. A cellulose acylate film produced by the method according to claim 1. Description: