JPH1121379A - Cellulose triacetate solution, preparation thereof, and preparation of cellulose triacetate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cellulose triacetate soln. that is highly stable and gives a film excellent in flatness, haze, and mechanical properties by dissolving cellulose triacetate having a specified average degree of acetylation in an org. solvent mainly comprising acetone substantially contg. no halogenated hydrocarbon under a specified pressure. SOLUTION: Cellulose triacetate having an average degree of acetylation of 58.0%-62.5 % is dissolved in an org. solvent mainly comprising acetone. contg. at least one solvent selected from among 4-12C ketones, 3-12C esters, 1-6C alcohols, 3-12C ethers, and 5-8C cyclic hydrocarbons, and/or contg. 30-100% acetone under a pressure of 10-5,000 kg/cm<2> pref. applied by a hydrostatic pressure method to give a soln. pref. with a concn. of 10-40 wt.%. Thus, the objective soln. is prepd. by a treatment at about normal temp. without using a halogenated hydrocarbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a halogenated hydrocarbon such as methylene chloride has been used as an organic solvent in 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. in use. 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 production process, so that drying is easy. Conversely, methylene chloride has a low boiling point, so it is easy to volatilize, has some leakage from hermetic equipment, has a limit in recovery, and has a problem that it cannot completely prevent its escape into the atmosphere. Recently, the importance of protecting the global environment has begun to be emphasized, and the use of this type of halogenated hydrocarbon has been regulated in view of destruction of the ozone hole and suspected carcinogenicity, and methylene chloride has no such problems. Anyway, methylene chloride, which is a halogenated hydrocarbon, is becoming subject to some regulations. Due to these problems, it has become urgent for those skilled in the art to search for or study a solvent for cellulose triacetate other than methylene chloride. Known organic solvents having solubility in cellulose acetate include acetone (boiling point: 56 ° C.), methyl acetate (boiling point: 56.3 ° C.),
Tetrahydrofuran (boiling point: 65.4 ° C), 1,3-dioxolane (boiling point: 75 ° C), nitromethane (boiling point: 1)
01 ° 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 are actually subjected to dissolution tests, some of them are not necessarily good solvents, and some have concerns such as explosions.
There were few practically usable ones such as those having a high boiling point.

[0003] Among the above organic solvents, acetone having a low boiling point has only been used to cause cellulose triacetate to swell and not be dissolved by ordinary methods.
Attempts have been made to dissolve cellulose triacetate in acetone to produce fibers and films.

[0004] M. G. FIG. Cowie and others are Makrom
ol. chem. 143, p. 105 (1971), cellulose triacetate (acetylation degree: 60.1% to 61.3%) was cooled from −80 ° C. to −70 ° C. in acetone, and then heated from 0.5 to 0.5%. It reports that a dilute solution dissolved at 5% by weight was obtained. Such a method of melting at a low temperature is called a cooling melting method. Also,
Kenji Ude et al. Describe a spinning technique using a cooling dissolution method in "Dry spinning of cellulose triacetate from an acetone solution" in Textile Machinery Society, Vol. 34, pp. 57-61 (1981).

Also, Japanese Patent Application Laid-Open Nos. 9-95538 and 9-95538
No. 95557 proposes applying a cooling dissolution method to film production using acetone and another organic solvent, against the background of the above technology. According to the above-mentioned study, it was necessary to lower the temperature to -30 ° C. despite the fact that acetone, which is a good solvent for cellulose triacetate, was originally used.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to dissolve cellulose triacetate in an organic solvent containing acetone as a main component without substantially using a halogenated hydrocarbon as a solvent for cellulose triacetate. An object of the present invention is to obtain a cellulose triacetate solution that dissolves at a temperature as close to room temperature as possible without using a cooling dissolution method of dissolving at −30 ° C.

[0007]

The above object of the present invention has been attained by the following cellulose triacetate solution (1).

(1) The average degree of acetylation is 58.0% or more.
10 kg / cm ² or more and 5000 kL or more in a liquid containing 5% or less of cellulose triacetate and containing an organic solvent containing acetone as a main component and substantially not containing a halogenated hydrocarbon.
A cellulose triacetate solution which is prepared by dissolving by applying a pressure of not more than g / cm ² . The present invention can be carried out in the following modes (2) to (7).

(2) The cellulose triacetate solution according to (1), which is pressurized by a hydrostatic pressure method.

(3) The organic solvent containing acetone as a main component is a ketone having 4 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, or an ester having 1 to 6 carbon atoms. (1) characterized by containing at least one solvent selected from alcohols, ethers having 3 to 12 carbon atoms and / or cyclic hydrocarbons having 5 to 8 carbon atoms. Or the cellulose triacetate solution according to (2).

(4) The cellulose triacetate solution according to any one of (1) to (3), wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%.

(5) The cellulose triacetate solution according to any one of (1) to (4), wherein the viscosity average polymerization degree of the cellulose triacetate is from 220 to 500.

(6) The cellulose triacetate is 1
The cellulose triacetate solution according to any one of (1) to (5), which is dissolved at a concentration of 0 to 40% by weight.

(7) The cellulose triacetate solution according to any one of (1) to (6), wherein the plasticizer is dissolved in 0.1 to 30 parts by weight based on 100 parts by weight of the cellulose triacetate. .

Further, the present invention has been achieved by the following method (8) for preparing a cellulose triacetate solution.

(8) The average acetylation degree is 58.0% or more.
10 kg / cm ² or more and 5000 kg or less to a mixture containing 5% or less of cellulose triacetate and containing an organic solvent mainly containing acetone substantially free of halogenated hydrocarbons.
A method for preparing a cellulose triacetate solution, comprising dissolving cellulose triacetate in the organic solvent by applying pressure in a step of applying a pressure of not more than kg / cm ² . Further, the present invention can be carried out in the following modes (9) to (14).

(9) The method for preparing a cellulose triacetate solution according to (8), wherein the solution is pressurized by a hydrostatic pressure method.

(10) The organic solvent containing acetone as a main component is selected from ketones having 4 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and 1 having carbon atoms.
(8) characterized in that it contains at least one solvent selected from alcohols having from 3 to 6 carbon atoms, ethers having from 3 to 12 carbon atoms and hydrocarbons having from 4 to 10 carbon atoms. Or the method for preparing a cellulose triacetate solution according to (9).

(11) The method for preparing a cellulose triacetate solution according to (8) or (10), wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%.

(12) The method for preparing a cellulose triacetate solution according to any one of (8) to (11), wherein the cellulose triacetate is dissolved at a concentration of 10 to 40% by weight.

(13) The method for preparing a cellulose triacetate solution according to any one of (8) to (12), wherein the viscosity average polymerization degree of the cellulose triacetate is from 220 to 500.

(14) The method for preparing a cellulose triacetate solution according to any one of (8) to (13), wherein the plasticizer is dissolved in 0.1 to 30 parts by weight per 100 parts by weight of cellulose triacetate. .

Further, the present invention also provides a method for producing a cellulose triacetate film of the following (15).

(15) Average degree of acetylation is 58.0% or more 6
A mixture containing not more than 2.5% of cellulose triacetate and containing an organic solvent containing acetone as a main component substantially free of halogenated hydrocarbons is 10 kg / cm ^{2 to} 50 kg.
Preparing a cellulose triacetate solution by applying a pressure of not more than 00 kg / cm ² , casting the cellulose triacetate solution from at least one pressing die onto a continuously conveyed endless support, A method for producing a cellulose triacetate film, comprising the steps of: evaporating a solvent to remove the cellulose triacetate support from the support, drying the film, and winding the film. Further, the present invention can be carried out in the following modes (16) to (21).

(16) The method for producing a cellulose triacetate film according to (15), wherein the pressurizing method in the solution preparation step is a hydrostatic pressure method.

(17) The organic solvent containing acetone as a main component is selected from ketones having 4 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and 1 having carbon atoms.
Alcohols up to 6 and 4 to 10 carbon atoms
(15) or (16), which contains at least one solvent selected from the group consisting of hydrocarbons
3. The method for producing a cellulose triacetate film according to 1.).

(18) The cellulose triacetate film according to any one of (15) to (17), wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%. Production method.

(19) The production of a cellulose triacetate film according to any one of (15) to (18), wherein a cellulose triacetate solution in which the cellulose triacetate is dissolved at a concentration of 10 to 40% by weight is used. Method.

(20) Viscosity average degree of polymerization of 220 or more and 50
The method for producing a cellulose triacetate film according to any one of (15) to (19), wherein the cellulose triacetate having a value of 0 or less is used.

(21) The method according to any one of (15) to (20), wherein the cellulose triacetate solution contains 0.1 to 30 parts by weight of a plasticizer based on 100 parts by weight of cellulose triacetate. A method for producing a cellulose triacetate film.

Hereinafter, the present invention will be described in detail.

The cellulose triacetate used in the present invention has a degree of acetylation of 58.0% to 62.5%, and in the present invention, a cellulose triacetate in this range is referred to as cellulose triacetate. Generally, cellulose acetate having a degree of acetylation of 53% to 56% is called cellulose diacetate, and cellulose acetate having a degree of acetylation of 58% to 62.5% is called cellulose triacetate. In addition to the degree of acetylation, the indication of the degree of reactivity includes the degree of substitution or the degree of acetylation. The acetylation degree is expressed as acetic acid (CH ₃ COOH) in terms of weight% when an acetic acid group reacts with a hydroxyl group of cellulose. The degree of acetylation is determined by the acetyl group (CH ₃ C
O), expressed in% by weight, and 44.8% when the reaction was the highest. The degree of substitution represents the degree to which the acetyl group has reacted with the OH group of the cellulose molecule. The case where the acetyl group has reacted with all OH is represented as 3.00. This means that three acetyl groups were substituted for three OH groups in the minimum glucose unit of the cellulose molecule. By the way, vinegar degree 5
The degree of acetylation in the case of 8.0% cellulose triacetate is 41.57% and the degree of substitution is 2.63. The degree of acetylation can be measured by the method described in the test method for cellulose acetate and the like in ASTM D-817-91.

The polymerization degree (viscosity average) of the cellulose triacetate used in the present invention is preferably from 220 to 500. Generally, a cellulose acetate film containing cellulose triacetate is required to have a degree of polymerization of 200 or more in order for the mechanical strength of the film, fiber, or molded product to be tough, and is disclosed in “Cellulose Handbook, Asakura Shoten (1958), edited by Hiroshi Marusawa and Kazuo Uda, "Plastic Materials Course 17", Nikkan Kogyo Shimbun (1970). The polymerization degree of the cellulose triacetate of the present invention is more preferably 250.
To 350. The viscosity average polymerization degree can be measured with an Ostwald viscometer, and is determined from the measured intrinsic viscosity [η] of cellulose triacetate by the following formula.

DP = [η] / Km where DP is the viscosity-average degree of polymerization, Km is a constant of 6 × 10 ^-4 The cellulose triacetate used in the present invention is preferably a photographic grade, and a commercially available photographic grade. Those having satisfactory qualities such as viscosity average polymerization degree, acetylation degree and low molecular weight component can be obtained. As a photographic grade cellulose triacetate maker, there are Daicel Co., Ltd., Coatles, Hoechst, Eastman Kodak and the like, and any photographic grade cellulose triacetate can be used. Among these cellulose triacetates, there are components that are difficult to dissolve even in a methylene chloride solvent system. In this case, it is necessary to remove the undissolved components by filtering the solution after preparing the solution. These hardly soluble components are said to be components having a low molecular weight and different acetylation degrees. Components having different molecular weights can be detected by a high performance liquid chromatography system (GPC-LALLS). It consists of a GPC-LALLS connected to a gel filtration column and a detector that detects refractive index and light scattering. There is virtually no problem because it is filtered in the filtration step,
The presence of these components is preferred because the clogging of the filter is rapid and the productivity is reduced. For removing these components, there is a method of extracting with a good solvent of cellulose triacetate.

The content of halogenated hydrocarbon such as methylene chloride in the organic solvent containing acetone as a main component substantially free of halogenated hydrocarbon according to the present invention is defined as substantially free of halogenated hydrocarbon. Is 5% by weight or less (preferably 2% by weight or less) in the mixed solvent. The organic solvent containing acetone as a main component is
It means that the acetone concentration in the mixed solvent is from 30% by weight to 100% by weight, and preferably 80% by weight or more. Organic solvents other than acetone have 4 to 12 carbon atoms.
Examples of the ketones include methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone, and methylcyclohexanone. Examples of the ester having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, and acetic acid. Propyl, butyl acetate, pentyl acetate, 2-ethoxy-ethyl acetate and the like. Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, propanol, iso-propanol, 1-butanol, t-butanol, and t-butanol. -Methyl-2-butanol, 2
-Methoxyethanol and 2-butoxyethanol and the like, and ethers having 3 to 12 carbon atoms include, for example, diisopropyl ether, dimethoxymethane,
It includes dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole, and the cyclic hydrocarbons having 5 to 8 carbon atoms include cyclopentane, cyclohexane, cycloheptane and cyclohexane. Octane and the like are included.
When these solvents are mixed, they may be mixed with acetone first, or the above-mentioned solvent may be gradually added to an acetone solution of cellulose triacetate with stirring. Preferably, first, acetone and the above solvent are mixed to dissolve the cellulose triacetate. Solvents used as a mixture with these acetones are those that promote the dissolution of acetone, such as methyl acetate, 1,3-dioxolane, and solvents having a boiling point higher than that of acetone. When it starts to evaporate, the cellulose triacetate solution is cast and loses fluidity, substantially increasing the film-forming speed, and those suitable for producing a good quality film such as flatness, for example, ethanol, isopropanol, butanol, And cyclohexane. It is preferable to use a mixed solvent suitable for each purpose. The plasticizer used in the present invention is added to increase the water resistance of the cellulose triacetate film and to improve the mechanical properties. Phosphoric acid esters or carboxylic acid esters are used as the plasticizer. Examples of the phosphate ester include triphenyl phosphate (TPP) and tricresyl phosphate (TPP).
CP), biphenyl diphenyl phosphate (BDP)
And phthalic acid esters as carboxylic acid esters include, for example, ethyl phthalylethyl glycolate (EPEG), dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB)
P), dioctyl phthalate (DOP), diethylhexyl phthalate (DEHP) and the like, and citrate esters such as acetyltriethyl citrate (OACT)
E), tributyl citrate (OACTB) and the like, and examples of other carboxylic acid esters include butyl oleate (BO), methylacetyl linoleate (MAL), dibutyl sebacate (DBS), various trimellitate esters Etc.

Further, the following formula (I), (II) or (III)
May be added.

[0037]

Embedded image

In the formula, R is an alkyl group having 1 to 4 carbon atoms. (I), (II) or (II)
Examples of the compounds represented by I) include 2,2'-phosphate
Methylenebis (4,6-di-t-butylphenyl) sodium (ADEKA STAB NA-10, manufactured by Asahi Denka Co., Ltd.),
Bis (p-methylbenzylidene) sorbitol (Gerol MD, manufactured by Shin Nippon Rika Co., Ltd.) and bis (p-ethylvindylidene) sorbitol (NC-4, manufactured by Mitsui Toatsu Chemicals, Inc.) are included.

In addition, additives such as a cellulose triacetate film deterioration inhibitor, an ultraviolet absorber and a light piping prevention dye can also be used in the cellulose triacetate solution. Regarding the deterioration preventive agent, see JP-A-Hei 5-
No. 1907073 and the UV inhibitor are described in JP-A-7-11056. As an organic solvent-soluble dye capable of coloring a film base and preventing light piping, examples of the organic dye soluble in a solvent include spirit black (manufactured by Chuo Kagaku) and nigrosine base EX (manufactured by Orient Chemical Industries).

The method of the present invention for dissolving cellulose triacetate in an organic solvent containing acetone as a main component is a completely novel method. As a method for dissolving cellulose triacetate in an acetone solvent, the above-mentioned cooling dissolution method is known, but this method is complicated by handling a refrigerant having a low temperature of -30 ° C. The present invention is an epoch-making method that can be dissolved at a very ordinary temperature without using such a low-temperature refrigerant. Although the action of dissolving cellulose triacetate in an organic solvent containing acetone as a main component is not clear, in general, the dissolution phenomena of a high molecular compound are not solvable because a good solvent is closely Is solvated around the molecule to form a relatively elongated random or rod-like shape, which is said to exist relatively independently. It is considered that the pressure dissolution method of the present invention facilitates the penetration of the organic solvent into the solid or swollen state of cellulose triacetate under the pressurized state, so that the cellulose triacetate molecules are easily loosened and solvated. In this sense, the present invention by pressurization is a novel dissolution method.

The method for dissolving cellulose triacetate under pressure in an organic solvent containing acetone as a main component of the present invention will be described. First, cellulose triacetate was added to an organic solvent containing acetone as a main component in a pressure vessel, and 10 kg /
A cellulose triacetate solution can be prepared only by applying a pressure of not less than cm ^{2 and not} more than 5000 kg / cm ² and returning to normal pressure. It is easy to take out the cellulose triacetate solution, and more than 10 kg / cm ^{2 and} 5000 k
Any device capable of applying a pressure of g / cm ² or less may be used.
The pressurization pressure of the present invention is 10 kg / cm ² or more and 5000 kg.
/ Cm ² or less, preferably 50 kg / c
m ² or more and 3000 kg / cm ² or less, more preferably 100 kg / cm ² or more and 2000 kg / cm ² or less.

The pressurizing method and pressurizing device of the present invention are not particularly limited as long as they are performed by a device capable of pressurizing. The pressurizing method and pressurizing device suitable for the present invention are used in other industries. Method and apparatus can be used, for example, a hydrostatic pressure method (Cold Isos
Atomic Press, abbreviated as CIP, or a rubber press method is also included) is preferable as a method and equipment capable of safely applying a high pressure. This hydrostatic pressure method and apparatus are preferable because a hydrostatic pressure can be uniformly applied to the mixture of cellulose triacetate and the organic solvent from all directions, and a cellulose triacetate solution having an excellent dissolved state can be obtained. Rubber or a metal which can be easily deformed by pressure, for example, an aluminum container may be used as the material of the container for enclosing the mixture in the hydrostatic pressure method. Alternatively, a method in which the mixture is sealed in an easily deformable closed container such as rubber, and the mixture is transferred and moved in the closed container while applying hydrostatic pressure, may be intermittently prepared. Alternatively, a means for compressing the mixture by placing the mixture in a container having a lid that can be slid up and down and pushing the lid in can be used. The mixture may be kneaded and extruded using a pressurized extruder. During the preparation of the cellulose triacetate solution of the present invention, pressurization may be performed intermittently, and the dissolution rate can be increased by repeating pressurization and normal pressure. The pressurizing device may or may not be equipped with a stirrer.

In the present invention, when dissolving cellulose triacetate in a mixture of organic solvents, the mixture is allowed to stand before pressurizing, for example, after being swelled for one day and night, and then dissolved under pressure. The dissolution may be carried out, but the latter is preferred when the pressure dissolution apparatus has room.

With respect to the pressurizing time for the preparation of the cellulose triacetate solution of the present invention, if the pressure is high, there is no problem in dissolving it if the pressure is at least 1 minute, and if the time is longer than 120 hours, the object of the present invention is not impaired. The time is too long, and the workability is poor, which is not preferable. Therefore, the time is preferably 120 hours or less, more preferably 10 minutes to 15 hours, particularly preferably 30 minutes to 8 hours.

The temperature for preparing the solution according to the present invention is not particularly limited, but the object of the present invention can be sufficiently achieved at around normal temperature.

A method for producing a film using the cellulose triacetate solution of the present invention will be described. A conventional facility for producing a cellulose triacetate film can be used. In brief, the prepared cellulose triacetate solution (hereinafter sometimes referred to as a dope) is sent to a pressurized die through a pressurized fixed-quantity gear pump that can perform high-precision fixed-quantity liquid supply by, for example, the number of rotations. The dope sent out from this precision gear pump is evenly cast on the endless support from the die (slit) of the pressurized die into which the dope is fed, and when the support has made almost one revolution, the dry film is supported. This is equipment that peels off from the body, dries it through a rotating roll group, and winds it to a predetermined length with a winder after transport.

The cellulose triacetate solution of the present invention is prepared so that the concentration of cellulose triacetate is from 10% by weight to 35% by weight. Preferably 15
To 25% by weight.

As the endless support used for producing the cellulose triacetate film of the present invention, a drum having a mirror-finished surface by plating or a stainless steel band having a mirror-finished surface by polishing is used.

The pressure die used in the production of the cellulose triacetate film of the present invention may be disposed on the support at one or more pressure dies. 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 liquid is sent to the dice at a respective ratio from a plurality of precision metering gear pumps.

Drying of the dope on the support in the production of the cellulose triacetate film of the present invention is generally carried out by heating from the surface of the drum or belt, that is, from the surface of the dope film on the support, drum or band. There is a method in which air is applied from the front or back surface of the band, and a liquid heat transfer method in which liquid is brought into contact with the back surface opposite to the dope surface of the band or drum to transfer heat to the surface of the drum or band. preferable. The temperature of the surface of the support before casting may be any number of times as long as it is lower than the boiling point of the solvent used in the cellulose triacetate solution (dope). However, in order to promote drying and to lose the fluidity of the dope on the support, it is preferable to set the dope at a temperature slightly lower than the boiling point of acetone.
The speed at which the cellulose triacetate film is produced depends on factors such as the length of the belt, the drying method, and the composition of the dope solvent. However, it can be said that it almost depends on the residual solvent when the dope film is peeled off from the belt. In other words, whether the dope can be peeled off from the belt depends on whether the solvent concentration near the belt surface of the dope film is too high, and the dope remains on the belt when the dope film is peeled off, hindering the next casting. There must not be. Therefore, the film at the time of peeling (though it may be better to say a doped film because it contains a large amount of solvent) must be strong enough to withstand peeling. The residual solvent at the time of peeling differs depending on the method of drying on the belt. The method of drying by blowing air from the surface of the dope is most common, and the method of transferring the heat on the back surface of the belt with a liquid is more efficient. In the present invention, the latter method, which is more efficient, is employed to measure the peeling residual solvent.

For the measurement of the residual solvent at the time of peeling, the weight of the cellulose triacetate dope film immediately after peeling was put into a sealed bottle, the weight D (g) of the dope film was immediately weighed, and then the whole sealed bottle was placed in an oven at 150 ° C. After drying for 3 hours and cooling to room temperature, the dry test film weight F (g) is measured and calculated as follows.

Residual solvent% after peeling = (D−F) / F × 100 Film drying in the production of the cellulose triacetate film of the present invention is carried out by removing the dope that has been peeled off immediately before the support makes one round and is already in the form of a film. The film is transported alternately through a group of rolls arranged in a zigzag pattern, or both ends of the dope film are transported in a non-contact manner by carrying both ends in a clip shape, and air at a predetermined temperature is applied to both sides of the film surface. This is done by:

The winding machine relating to the production of the cellulose triacetate film of the present invention may be of a generally used constant tension type.

The thickness of the finished film of the present invention varies depending on the purpose of use, but the thickness of the solid contained in the dope, the slit width of the dice, the dice pressure, the casting speed, and the like are controlled so as to be 5 to 500 μm. The thickness may be adjusted, and the thickness after drying is preferably from 20 to 200 μm, more preferably from 60 to 125 μm.

The method for measuring the chemical and physical properties of the cellulose triacetate, cellulose triacetate solution and cellulose triacetate film used in the present invention will be described.

1) Degree of acetylation (%) of cellulose triacetate Degree of acetylation shall be measured by a saponification method. The dried cellulose triacetate was precisely weighed and dissolved in a mixed solvent of acetone and dimethylsulfoxide (volume ratio: 4: 1), and then a predetermined amount of a 1N aqueous sodium hydroxide solution was added, followed by saponification at 25 ° C for 2 hours. . Add phenolphthalein as an indicator and add 1N sulfuric acid (concentration factor;
Excess sodium hydroxide was titrated in F). A blank test was performed in the same manner as described above. Then, the degree of acetylation (%) was calculated as follows.

Degree of acetylation (%) = (6.05 × (BA) × F) / W In the formula, A is 1N sulfuric acid (ml) required for titration of the sample, and B is 1N required for blank test. Sulfuric acid amount (ml), F is 1N
The sulfuric acid factor, W, indicates the sample weight.

2) Viscosity-average degree of polymerization (DP) of cellulose triacetate About 0.2 g of absolutely dried cellulose triacetate was precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (weight ratio). This was measured for drop seconds at 25 ° C. using an Ostwald viscometer, and the degree of polymerization was determined by the following equation.

Η _rel = T / T _s [η] = (ln η _rel ) / CDP = [η] / Km where, T: falling seconds of the measurement sample T _s : falling seconds of the solvent alone C: concentration (G / l) Km: 6 × 10 ^-4

[0060]

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

Example 1 Cellulose triacetate 250 having an average degree of acetylation of 61.2% and a viscosity average degree of polymerization of 310
g, acetone 1000 g and diethyl phthalate (DE
P) 15 g was mixed in a container with a lid. At room temperature, the cellulose triacetate was swollen in acetone without dissolving. Next, the swollen cellulose triacetate mixture was placed in a 100 μm-thick aluminum container (with an inner volume of 1 μm).
000 cc), covered with aluminum foil so as not to leave air, and sealed by caulking. The sealed container is packed in a rubber bag, and after lightly degassing, the rubber bag is sealed. This rubber bag was set in a rubber isostatic pressing device (manufactured by Kobe Steel) for ceramic molding.
Pressurize at a pressure of kg / cm ² for 2 hours. After pressurization, the pressure was returned to atmospheric pressure, the aluminum container was taken out of the rubber bag, the lid of the aluminum container was taken out, transferred to a glass container, and the dissolution state was visually observed. As a result, all of the cellulose triacetate was dissolved in acetone ( There was no insoluble matter), and a transparent and uniform dope was obtained. The conditions of Example 1 were changed as follows to prepare the cellulose triacetate solutions of Table 1, Examples 2 to 6.

[Examples 2 to 6]

[0063]

[Table 1]

[Examples 7, 8 and 9] Instead of the acetone of Example 1, Examples 7 and 8 used methyl acetate, and Example 9 used a mixed solvent of 1000 parts by weight of acetone and 150 parts by weight of methyl acetate. The procedure was carried out in the same manner as in Example 1, except that the solvent was used as a solvent for triacetate, and the pressure for dissolution was changed as follows.

[0065]

[Table 2]

The solubility of the samples of Examples 1 to 9, the transparency of the solution, and the stability of the solution were observed.

(Evaluation of Stability of Solution of Cellulose Triacetate) A solution sampled within one hour from the preparation method of the cellulose triacetate solution of the present invention and the conditions around the present invention was taken in a test tube, and sealed. Observe the state of the solution left at room temperature (23 ° C) for 10 days,
The evaluation was made in three stages of A, B and C.

A: Even after lapse of 10 days, transparency and uniformity are maintained, and good solubility and solution stability are exhibited.

B: In the early stage of standing, the solution exhibits transparency and uniformity and exhibits good solution properties, but after 3 days, phase separation occurs, resulting in a non-uniform state.

C: The slurry became non-uniform within one hour after standing, and did not show a solution state having transparency and uniformity.

[Results] Table 3 shows the results of observing the solubility, solution transparency, and solution stability of the solutions of Examples 1 to 9.
Shown in

[0072]

[Table 3]

As described above, the cellulose triacetate solution of the present invention dissolved by applying hydrostatic pressure had good solubility, good transparency of the solution, and excellent stability of the solution.

Example 10 Cellulose triacetate 250 having an average degree of acetylation of 61.2% and a viscosity average degree of polymerization of 320
g, acetone 950 g, 1-butanol 50 g and diethyl phthalate (DEP) 15 g were stirred and mixed in a container with a lid. By changing the pressurization time of Example 1 to 30 minutes,
Thereafter, the mixture was dissolved in the same manner as in Example 1, and after being pressurized, removed, and visually observed, cellulose triacetate was completely dissolved, and a uniform dope was obtained.
In Examples 7 and 8, precipitation was observed without any apparent stability.

Examples 11 to 13 Cellulose triacetate solutions were prepared as shown in Table 4 in the same manner as in Example 1 except that the following solvent was used in place of 1-butanol.

[0076]

[Table 4]

Comparative Example 1 A dope using methylene chloride as a solvent composition, which has been conventionally used as a base for a color film, was prepared as follows. 250 g of cellulose triacetate having an acetylation degree of 61.2%, 840 g of methylene chloride, 160 g of ethanol, and 15 g of ethylphthalylethyl glycolate (EPEG) were mixed and dissolved in a dissolving vessel equipped with a stirrer for 8 hours, and a cellulose triacetate solution (dope) was obtained. Obtained.

Comparative Example 2 A dope was prepared in the same manner as in Comparative Example 1 using the same methylene chloride. Cellulose triacetate 25 with a degree of acetylation of 61.2%
0 g, methylene chloride 950 g, methanol 50
g, ethylphthalylethyl glycolate (EPEG) 1
5 g was dissolved and prepared in a cellulose triacetate solution in the same manner as in Comparative Example 1.

Embodiment 14 Embodiments 1 and 11 to 13
The cellulose triacetate solutions (dopes) of Comparative Examples 1 and 2 were placed in a sealed kettle, the air was replaced with nitrogen gas, and the dope was sent from the bottom of the kettle to the die with a pressure pump while applying nitrogen pressure. The dope was extruded and cast from a die of a pressing die onto a rotating endless stainless belt having a total length of 8 m and a width of 450 mm at a speed while adjusting with a constant volume gear pump so that the dry film thickness became 120 μm. Dry from the back side of the stainless steel belt while contacting it with hot water of 45 ° C.
Hot air at 100 to 15 ° C. was blown through a group of rolls arranged in a zigzag pattern to dry, and then wound up as a film. Table 5 shows the results of observation and measurement of the flatness and haze of these film samples. Example 1 and Comparative Example 2
Was formed at a speed of 1.8 m / min.

[Results] Each sample is abbreviated as follows.

[0081]

[Table 5]

Here, Ac is acetone, 1-
BtOH stands for 1-butanol, CH for cyclohexane, MA for methyl acetate, MC for methylene chloride, EtOH for ethanol, and MeOH for methanol.

The film was observed for flatness and measured for haze.

(Evaluation of Flatness of Dried Film) A method for preparing the cellulose triacetate solution of the present invention and the cellulose triacetate solution prepared under the peripheral conditions of the present invention were cast from a die onto a support, formed into a film, and dried. Then, the flatness of the film was observed and evaluated on the following three grades of A, B and C.

A: The flatness is excellent.

B: When viewed closely, a slightly streak-like thing is seen.

C: The entire surface is streak-like.

(Measurement of Haze of Film) Each of the formed films was measured using a haze meter (Model 1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

[Results]

[0090]

[Table 6]

As described above, the film using the solvent used together with acetone showed the flatness and haze of the film which was inferior to the conventional film using methylene chloride.

Example 15 The mechanical properties of the film formed in Example 14 were measured.

(Film Tensile Test) A film having a length of 100 mm and a width of 10 mm was subjected to an initial sample length of 5 mm in accordance with the standard of ISO 1184-1983.
It was measured at 0 mm and a tensile speed of 20 mm / min to determine the tensile strength.

(Film Tear Test) A sample obtained by cutting each formed film into 50 mm × 64 mm was subjected to ISO
The tear load required for tearing was determined according to the standard of 6383 / 2-1983.

(Film Folding Resistance Test) A sample obtained by cutting each formed film into a length of 120 mm was subjected to ISO.
According to the standard of 8776 / 2-1988, the number of reciprocations until cutting was determined by bending.

[Results]

[0097]

[Table 7]

It was found that the mechanical properties of a film prepared by the pressure dissolution method using acetone of the present invention were equivalent to those of a film prepared using methylene chloride which had been conventionally used.

[0099]

According to the present invention, a cellulose triacetate solution having high stability can be obtained. Further, the cellulose triacetate solution of the present invention has an effect that handling is easy. Further, according to the present invention, it is possible to produce a cellulose triacetate film having excellent flatness, haze, and mechanical properties without using a halogenated hydrocarbon-based organic solvent such as methylene chloride.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03C 1/795 G03C 1/795 // B29K 1:00 B29L 7:00

Claims (21)

[Claims] An average degree of acetylation of 58.0% or more and 62.5%.
The following liquid containing an organic solvent containing acetone as a main component containing cellulose triacetate and containing substantially no halogenated hydrocarbon is added in an amount of 10 kg / cm ² or more and 5000 kg /
A cellulose triacetate solution prepared by applying a pressure of not more than cm ² . 2. The cellulose triacetate solution according to claim 1, wherein the solution is pressurized by a hydrostatic method. 3. The organic solvent containing acetone as a main component is a ketone having 4 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, or an alcohol having 1 to 6 carbon atoms. And at least one solvent selected from ethers, ethers having 3 to 12 carbon atoms and cyclic hydrocarbons having 5 to 8 carbon atoms. The cellulose triacetate solution according to the above. 4. The cellulose triacetate solution according to claim 1, wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%. 5. The cellulose triacetate solution according to claim 1, wherein the viscosity average polymerization degree of the cellulose triacetate is 220 or more and 500 or less. 6. The cellulose triacetate solution according to claim 1, wherein the cellulose triacetate is dissolved at a concentration of 10 to 40% by weight. 7. The cellulose triacetate solution according to claim 1, wherein 0.1 to 30 parts by weight of a plasticizer is dissolved in 100 parts by weight of the cellulose triacetate. 8. The average degree of acetylation is at least 58.0% and at least 62.5%.
10 kg / cm ² or more and 5000 kg of a mixture containing the following cellulose triacetate and an organic solvent containing acetone as a main component substantially free of halogenated hydrocarbons:
A method for preparing a cellulose triacetate solution, wherein cellulose triacetate is dissolved in the organic solvent by applying a pressure of not more than / cm ² . 9. The method for preparing a cellulose triacetate solution according to claim 8, wherein the pressure is increased by a hydrostatic pressure method. 10. The organic solvent containing acetone as a main component includes ketones having 4 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and alcohols having 1 to 6 carbon atoms. 10. The method according to claim 8, wherein the solvent contains at least one solvent selected from the group consisting of ethers having 3 to 12 carbon atoms and cyclic hydrocarbons having 5 to 8 carbon atoms. A method for preparing a cellulose triacetate solution. 11. The method for preparing a cellulose triacetate solution according to claim 8, wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%. 12. The cellulose triacetate of claim 10
The method for preparing a cellostriacetate solution according to any one of claims 8 to 11, wherein the solution is dissolved at a concentration of from about 40% by weight. 13. The method for preparing a cellulose triacetate solution according to claim 8, wherein the viscosity average polymerization degree of the cellulose triacetate is 220 or more and 500 or less. 14. The method for preparing a cellulose triacetate solution according to claim 8, wherein 0.1 to 30 parts by weight of a plasticizer is dissolved in 100 parts by weight of the cellulose triacetate. 15. An average degree of acetylation of 58.0% or more and 62.5% or more.
% Include the following cellulose triacetate, 5000 10kg / cm ² or more, the mixture comprising the organic solvent mainly comprising acetone containing no halogenated hydrocarbon substantially
applying a pressure of not more than kg / cm ² to prepare a cellulose triacetate solution, casting the cellulose triacetate solution from at least one pressing die onto a continuously conveyed endlessly rotating support, A method for producing a cellulose triacetate film, comprising: evaporating a solvent on a support to peel off the cellulose triacetate support; drying the film; and winding the film. 16. The method for producing a cellulose triacetate film according to claim 15, wherein the pressurizing method in the solution preparation step is a hydrostatic pressure method. 17. The organic solvent containing acetone as a main component is a ketone having 4 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, or an alcohol having 1 to 6 carbon atoms. 17. A solvent according to claim 15, comprising at least one solvent selected from the group consisting of ethers having 3 to 12 carbon atoms and cyclic hydrocarbons having 5 to 8 carbon atoms. A method for producing a cellulose triacetate film. 18. The method for producing a cellulose triacetate film according to claim 15, wherein the concentration of acetone in the organic solvent containing acetone as a main component is 30% to 100%. 19. The method according to claim 19, wherein the cellulose triacetate comprises 10
The method for producing a cellulose triacetate film according to any one of claims 15 to 18, wherein a cellulose triacetate solution having a concentration of from about 1 to about 40% by weight is used. 20. The method for producing a cellulose triacetate film according to claim 15, wherein the cellulose triacetate having a viscosity average degree of polymerization of 220 or more and 500 or less is used. 21. The cellulose triacetate according to claim 15, wherein the cellulose triacetate solution contains 0.1 to 30 parts by weight of a plasticizer based on 100 parts by weight of the cellulose triacetate. Film production method.