JPH0952274A - Method and apparatus for manufacturing film from solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably form a thin film by extruding polymer solution by a screw type extruder disposed vertically, and degassing the solution in the extruder. SOLUTION: A material inlet 21 is provided at a screw type extruder 1 disposed vertically, and polymer solution 24 in a barrel 23 is extruded by rotation of a screw 22. The gas in the solution is separated from the solution by the pressure generated in the extruder 1, and extruded upward via the gap between the top face of the spiral wall 28 of the screw 22 and the inner surface of the barrel 23. Bubble fed to a spare chamber 27 are further effectively separated from the solution by agitating by an agitating blade 29, and extracted upward by the own buoyancy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a solution film-forming film, and more particularly to a solution film-forming film which can be easily degassed (defoamed) from an extruded polymer solution in the polymer extrusion step. Manufacturing method and device.

[0002]

2. Description of the Related Art A solution film forming method is known in which a plastic film is formed from a polymer solution in which a polymer is dissolved in a solvent. For example, a polymer solution prepared by dissolving an aromatic polyamide in an organic solvent is extruded from an extruder, cast from a die onto a support such as a drum or an endless belt in a sheet form, and the sheet is heated and dried to remove the solvent. It is a method of cooling the obtained sheet and forming it into a film. If necessary, the film is stretched uniaxially or biaxially and wound up by a winder.

In such a solution film-forming method, when a gas such as air is contained in the polymer solution, immediately after the polymer solution is cast on the support, the pressure applied until then is increased. Due to the expansion of the gas due to release, a perforated state is formed, and the target thin film cannot be obtained.

In order to remove the mixed gas and prevent the inconvenience described above, there is a method of extruding the polymer solution into a thread or a film in vacuum (in a reduced pressure atmosphere) to remove the gas.

However, this degassing method has a drawback that the viscosity of the polymer solution changes because the solvent also diffuses in vacuum. In addition, since a vacuum device and equipment such as a special mouthpiece for extruding into a vacuum are required, the equipment is large and expensive.

[0006]

An object of the present invention is to efficiently degas a polymer solution before casting in solution casting so that a thin film can be stably formed.

[0007]

In order to solve the above-mentioned problems, a method for producing a solution film-forming film according to the present invention is such that a polymer solution is extruded by a screw type extruder arranged vertically and the vertical type extruder is used. Degassing the polymer solution therein.

In this method, it is preferable that a preliminary chamber is formed at the upstream end of the barrel of the extruder in the flow direction of the polymer solution, and the polymer solution is degassed in the preliminary chamber while stirring.

As the polymer solution, for example, an aromatic polyamide film of 5 to 25% by weight and an organic solvent of 95 to 75% by weight is used, and the aromatic polyamide film can be produced by a solution casting method. In addition to this, polyimide, triacetate, polycarbonate film and the like are available as the plastic film by the solution casting method to which the present invention can be applied.

Further, the apparatus for producing a solution film-forming film according to the present invention is equipped with a screw type extruder arranged vertically as a polymer solution extruding means capable of degassing from the polymer solution being extruded. And consists of

In this apparatus, a preliminary chamber is formed at the upstream end of the extruder in the polymer solution flow direction by expanding the diameter of the barrel, and the screw is preferably provided with a stirring blade extending into the preliminary chamber.

The gap between the top surface of the screw wall of the extruder and the inner surface of the barrel is 0.25 to 5 mm, and more preferably 1 mm.
It is preferably ˜2 mm.

In the method and apparatus for producing such a solution film-forming film, since the screw type extruder is arranged vertically, when the polymer solution is extruded through the extruder, it is generated as the screw rotates. The gas is separated from the polymer solution by the appropriate internal pressure and separated gas (bubble)
Is naturally degassed (defoamed) upward due to the internal pressure and its buoyancy. Therefore, degassing can be performed very efficiently with a simple arrangement structure, and the occurrence of inconvenience due to gas inclusion can be effectively prevented.

Particularly, if a preliminary chamber is formed at the upstream end of the barrel of the vertical extruder in the flow direction of the polymer solution, and a screw is provided with a stirring blade to stir the polymer solution in the preliminary chamber, degassing can be performed more efficiently.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a solution film-forming film manufacturing apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a screw type extruder arranged vertically, and a polymer solution as a raw material is charged into the extruder 1. The polymer solution extruded from the extruder 1 is discharged in a thin film form from the die 4 through the gear pump 2 and the filter 3. The thin film 5 of the discharged polymer solution is
In the present embodiment, it is cast on a revolving endless belt 6 as a support, heated and dried in an oven 7, and desolvated.

Subsequently, the thin film is cold-formed by the cooling device 8 and, if necessary, stretched in the longitudinal direction. Cooling device 8
Is composed of a water-cooled device in this embodiment. The formed sheet (film) is guided to the tenter 9, dried, and stretched in the width direction as necessary. The thickness of the obtained film 10 is measured by the thickness measuring device 11, and if necessary, defects are detected online, and the film 10 is wound up by the winder 12.

An aromatic polyamide film is a typical example of the solution film-forming film of the present invention. For example, when the aromatic polyamide is obtained from acid chloride and diamine, it is solution polymerized in an aprotic organic polar solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, or interfacial polymerization using an aqueous medium. It is synthesized by. The polymer solution produces hydrogen chloride as a by-product when acid chloride and diamine are used as monomers, but when neutralizing this, calcium hydroxide, calcium carbonate,
Inorganic neutralizers such as lithium carbonate, and organic neutralizers such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine and diethanolamine are used. The reaction between the isocyanate and the carboxylic acid is performed in an aprotic organic polar solvent in the presence of a catalyst.

These polymer solutions may be used directly as a film forming stock solution, or the polymer may be isolated once and then redissolved in the above organic solvent or an inorganic solvent such as sulfuric acid to prepare a film forming stock solution. Good.

The intrinsic viscosity of the aromatic polyamide film polymer (value measured at 30 ° C. in a solution of 0.5 g of the polymer in 100 ml of sulfuric acid) is preferably 0.5 or more.

Inorganic salts such as calcium chloride, magnesium chloride, lithium chloride, etc. are used as a dissolution aid in the stock solution for film formation.
In some cases, lithium nitrate or the like is added. The polymer concentration in the stock solution is preferably about 2 to 40% by weight.

Examples of the method for adding these particles include a method in which the particles are sufficiently slurried in a solvent in advance and then used as a solvent for polymerization or a solvent for dilution, or a method in which the particles are directly added after preparing a stock solution for film formation.

The stock solution for film formation prepared as described above is formed into a film by a so-called solution film forming method. The solution film-forming method includes a dry-wet method, a dry method, and a wet method, and any method may be used for film formation. Here, the dry-wet method shown in FIG. 1 will be described as an example.

When a film is formed by a dry-wet method, the stock solution is extruded from a die onto a support such as a drum or an endless belt made of a material such as nickel, stainless steel, copper, titanium, hastelloy, tantalum, and then applied. The solvent is scattered from the thin film layer and dried until the thin film has self-holding property. Drying conditions are in the range of room temperature to 250 ° C and within 60 minutes, preferably in the range of room temperature to 200 ° C. When the drying temperature exceeds 250 ° C, voids are generated due to rapid heating,
Roughness of the surface occurs, making it impossible to obtain a practical film as an industrial material or magnetic material.

The film that has undergone the dry process is peeled from the support and introduced into the wet process, where the solvent and impurities contained in the film are removed. This bath is generally composed of an aqueous medium, and may contain an organic solvent, an inorganic salt or the like in addition to water. However, in general, the water content is 30% or more, preferably 50% or more, and the bath temperature is usually 0 to 100 ° C. Further, the bath temperature is set to 50 to reduce impurities in the film.
It is effective to raise the temperature above ℃ or to pass a bath of organic solvent through it.

The film from the wet process is further stretched,
The film is dried and heat-treated to form a film.

The film formed as described above is stretched in the film-forming process, and the stretching ratio is 0.8 to 5.0 in terms of areal magnification (area is the film area after stretching). It is defined as a value divided by the area of the previous film. 1 or less means relax.), And more preferably 1.1 to 3.0. Further, the dimensional change rate can be reduced by gradually cooling the film after the heat treatment.

In the present invention, in the solution casting as described above, the polymer solution is extruded by the vertical extruder. As shown in FIG. 2, the vertical screw-type extruder 1 is provided with a raw material inlet 21, and the rotation of the screw 22 causes the polymer solution 24 in the barrel 23 to flow.
Is extruded. The screw 22 is rotated and controlled at a predetermined rotation speed by a driving unit 25, for example, a unit including a motor and a speed reducer. The material of the screw 22 and the barrel 23 is not particularly limited, but stainless steel is preferable.

The barrel 23 has a jacket 26 in which, for example, hot water is passed to control the temperature to a predetermined temperature. At the upstream end of the barrel 23 in the flow direction of the polymer solution, a preliminary chamber 27 is formed by expanding the diameter of the barrel 23. The preliminary chamber 27 temporarily stores the polymer solution and is then extruded.

The spiral wall 28 of the screw 22 is formed integrally with the screw body at a predetermined pitch. Stirring blades 29 are formed in the auxiliary chamber 27 at the same pitch as the spiral wall 28, that is, as an expanded diameter wall of the spiral wall 28. The gap between the top surface of the spiral wall 28 portion other than the stirring blade 29 and the inner surface of the barrel 23 is preferably in the range of 0.25 to 5 mm, and more preferably 1 to 2 mm.

The polymer solution extruded by the screw 22 is sent from the discharge port 30 to the gear pump 2.

The intermediate hopper 31 is provided on the raw material charging port 21.
In the case of providing, the intermediate hopper 31 can be depressurized and used. The pressure in the intermediate hopper 31 is preferably about 10 to 760 Torr.

The polymer solution is extruded using the apparatus as described above. Pressure is generated in the extruder 1 by the rotation of the screw 22, but the raw material is aromatic polyamide, for example, the polymer solution is 5 to 25% by weight of aromatic polyamide,
When the organic solvent is 95 to 75% by weight, the screw rotation speed is controlled so that the pressure is 5 to 30 kg / cm ² . If it exceeds 30 kg / cm ² , the gas may dissolve in the polymer, and if it is less than 5 kg / cm ² ,
Poor in deaeration (defoaming) ability. Particularly preferably 10 to 2
It is 0 kg / cm ² .

Due to the above-mentioned pressure generated in the extruder 1, the gas in the polymer solution is separated from the polymer solution, and the screw 22 is pushed upward through the gap between the top surface of the spiral wall 28 and the inner surface of the barrel 23. Be done. Reserve room 2
The bubbles reaching No. 7 are more effectively separated from the polymer solution by the stirring by the stirring blades 29, and escape upward by the buoyancy of themselves.

[0034]

EXAMPLES The present invention will be described below with reference to examples. Example 1 A solution of 11% by weight of an aromatic polyamide and 89% by weight of a solvent (N-methylpyrrolidone) was put into a vertical extruder, and after heating a polymer temperature to 30 to 40 ° C., a throttle valve provided at an outlet was adjusted. Then, the ink was discharged at a back pressure of 10 kg / cm ² . As a result of observing the outlet polymer, a good polymer containing no bubbles was obtained.

Comparative Example 1 When a back pressure of 3 kg / cm ² was discharged under the same conditions, 1 to 2 bubbles were recognized per 1 liter of polymer. Therefore, it was found that controlling the internal pressure of the extruder within an appropriate range is extremely important for degassing.

Comparative Example 2 The above-mentioned extruder was arranged in a horizontal type which is a usual arrangement, and
When the polymer solution was discharged under the same conditions as above, 1-2 bubbles were still recognized per 1 liter of the polymer. Therefore, it was found that the vertical arrangement of the extruder as in the present invention is extremely effective for deaeration.

[0037]

As described above, according to the present invention,
The gas contained in the polymer solution extruded from the extruder is eliminated, and troubles such as pinholes and perforations do not occur in the thin film of the polymer solution cast on the support, and the production stability is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a solution film-forming film manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a partial vertical cross-sectional view around the extruder of the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Gear pump 3 Filter 4 Base 5 Thin film 6 Endless belt 7 Oven 8 Cooling device 9 Tenter 10 Film 11 Thickness measuring device 12 Winder 21 Raw material inlet 22 Screw 23 Barrel 24 Polymer solution 25 Driving means 26 Jacket 27 Preparatory chamber 28 Helical Wall 29 Stirring Blade 30 Discharge Port 31 Intermediate Hopper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 77/00 LQX C08L 77/00 LQX // B29K 77:00 B29L 7:00

Claims (7)

[Claims] 1. A method for producing a solution film-forming film, which comprises extruding a polymer solution by a screw type extruder arranged in a vertical type and degassing the polymer solution in the vertical type extruder. 2. The method for producing a solution film-forming film according to claim 1, wherein the polymer solution is degassed while being stirred in a preliminary chamber formed at the upstream end of the barrel of the extruder in the flow direction of the polymer solution. 3. The polymer solution is aromatic polyamide 5-5.
The method for producing a solution film-forming film according to claim 1 or 2, which comprises 25% by weight and an organic solvent of 95 to 75% by weight. 4. The method for producing a solution film-forming film according to claim 3, wherein the pressure generated in the barrel as the screw of the extruder rotates is 5 to 30 kg / cm ² . 5. An apparatus for producing a solution film-forming film, comprising as a polymer solution extruding means, a screw type extruder arranged in a vertical type capable of degassing from a polymer solution being extruded. 6. The solution according to claim 5, wherein a preliminary chamber is formed by expanding the diameter of the barrel at the upstream end of the extruder in the polymer solution flow direction, and the screw is provided with a stirring blade extending into the preliminary chamber. Membrane film manufacturing equipment. 7. The apparatus for producing a solution film-forming film according to claim 5, wherein the gap between the top surface of the spiral wall of the screw of the extruder and the inner surface of the barrel is 0.25 to 5 mm.