JPH044026A - Production of hollow fiber for filtration - Google Patents

Abstract

PURPOSE:To obtain a hollow fiber for filtration easy to operate and handle with superior productivity by impregnating a mixed liq. consisting of a polymer, a solvent and a nonsolvent into a fiber, converting the polymer into gel, removing the solvent and nonsolvent and carrying out drying. CONSTITUTION:A soln. prepd. by dissolving a polymer such as polyacrylonitrile or polysulfone in a solvent such as dimethylformamide or dimethylacetamide is mixed with a nonsolvent such as glycerol or diethylene glycol and this mixed. liq. is stuck to or impregnated into a single fiber or twine obtd. by twining plural fibers. The polymer is then converted into gel by immersion in a coagulating liq., the solvent and nonsolvent are removed by washing from the resulting microporous film of the polymer gel and the film is dried and coiled. A hollow fiber for filtration easy to operate and handle can be obtd. with superior productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application The present invention relates to a method for manufacturing hollow fibers having micropores used for separation and purification of substances.

Conventional technology and its problems Conventionally, in boat fishing, the method of manufacturing hollow fibers with micropores is to dissolve a polymer material in a solvent, and then mix a non-solvent with this solution to form a uniform mixture ( (hereinafter referred to as dope)
make. Next, using an extruder, for example, the dope is extruded through a nozzle into the air or into a coagulating liquid, gelled into a thread, and subjected to appropriate treatment and wound up. At this time, in order to make the thread hollow, air is simultaneously blown into the center of the thread cross section when extruding the dope from the nozzle μ, and the thread is extruded into the air or into the coagulating liquid to gel.

Case 2: 1 Since the dope is made small and hollow using an extruder, a structure for blowing air is required, which makes the structure of the nozzle and attached parts complicated, so care must be taken when handling it. It is inconvenient to have to do so. Moreover, the strength of the hollow fibers immediately after gelling the dope is very weak, and therefore care must be taken when handling them.Objective of the InventionThe object of the present invention is to easily control the pore diameter and to provide a simple It is an object of the present invention to provide a method for manufacturing hollow fibers for filtration that can be manufactured using a manufacturing device, is easy to operate and handle, and has excellent productivity.

Structure of the Invention In order to achieve the above-mentioned objects, the present invention provides a solution in which the above-mentioned polymeric material is dissolved in a solvent to form a thread made of a single fiber or a plurality of fibers twisted together as a base material, and a microporous membrane. A dope to which a non-solvent has been added, a step of adhering and impregnating the dope to the single fiber or a thread made of twisted plural fibers, and a step of adhering and impregnating the dope to the base material, followed by immersion in a coagulating solution, A process that includes a process of gelling the molecular material, a washing process of removing solvent and non-solvent from the gelled microporous membrane of the polymer, a drying process of drying the microporous membrane, and a subsequent winding process. In the above process, the dope is adhered to and impregnated into the base material, and then pulled out in an atmosphere under certain dope conditions to evaporate the solvent or absorb moisture to gel the polymer material and form micropores. This is a method for producing hollow fibers for filtration, which is characterized by having a gelation-coagulation step to form a membrane, and a subsequent winding step.

In the present invention, by controlling the cohesive force of the resin during coagulation, the dope adhering to and impregnating the base material shrinks after forming a film during gelation and coagulation, and the base material partially forms a film around the base material. This method of manufacturing hollow fibers is characterized by forming an appropriate gap between the material and the outer microporous membrane that has a part that is in close contact with the material.

Example Hereinafter, the details of the present invention will be explained with reference to Examples.

FIG. 1 is a schematic diagram of a manufacturing apparatus of the present invention, and FIG. 2 is a sectional view of a hollow fiber for filtration according to the present invention.

Here, 1 is a base material, 2 is a microporous membrane, 3 is a void, 4 is an ink pan, 5 is a dope solution, 6 is a gelling chamber, 7 is a primary washing tank,
8 is a V-yawer, 9 is a secondary washing tank, 10 is a drying room, and 11 is a winding unit. The base material is a single fiber or a yarn made of multiple fibers twisted together, and is made of polyester, polypropylene, or polyethylene. If necessary, it is also possible to use a material that has been subjected to surface treatment such as coating with a release agent to provide surface releasability.

The polymeric material forming the microporous membrane can be selected from polyacrylonitrile, polysulfone, polyethersulfone, acetylcellulose, polyamide, polyimide, polyviny-y alcohol, polyvinylidene fluoride, polyvinyl chloride, regenerated cellulose, etc. .

Similarly, the solvents for these polymeric materials are dimethyamide, dimethylacetamide, N-methy/L/-2-
It is suitably selected from among pyrrolidone, dimethyzol-hoki'F, methylene methylene, nclohexanone, acetone, etc., depending on the type of polymeric material.

The non-solvent added to the polymer solution can be selected from glycerin, diethylene glycol, triethylene glycol, polyethylene glycol, etc., which have no solubility in the polymer material and have hygroscopic properties.

The dissolved concentration of the polymeric material in the solvent is usually 5 to 50% by weight, preferably 8 to 15% by weight; if this concentration is too high, the water permeability of the membrane obtained will be low, and the concentration will be too low. Therefore, a film with sufficient strength cannot be obtained.

One of the coagulation conditions for forming a microporous membrane used in the present invention is the so-called drying method in which coagulation is performed in an atmosphere under certain conditions;
f20 to 40°C and humidity 50 to 95%, more preferably temperature 25 to 65°C and humidity 70 to 80%. Moreover, the mixed gas in the atmosphere is blown in a flow perpendicular or parallel to the surface of the film to be formed. in this case,
Wind speed is preferably 0.1 to 7'/sea, more preferably 3 to 7'/sea.
It is best to blow wind at a rate of 5”/sea at right angles.

In addition, when immersing in a coagulation liquid, the coagulation liquid should be one that does not substantially dissolve the film-forming polymeric material and has good miscibility with the solvent used, and should be compatible with the non-solvent applied in advance. The coagulating liquid to be immersed may be of different types or of the same type, but water is most commonly used.

Example 1 Polyether sulfone 209, dimethy-sulfoxide 5
29. A 30° C. dope solution containing 28 g of diethylene glyco-A was impregnated into a polyester fiber thread having a diameter of 650 μm to 750 P and serving as a base material. After that, it was pulled out of the dope solution, and the 5"/
A gel was formed by blowing air at sec. Then, it is immersed in water at 30°C to solidify. After coagulating for 2 minutes, it was thoroughly washed with water and dried. The obtained hollow fiber has a pore diameter of about 0.1
Water permeability at pm 15sl/(yj-iat 70sa H
It was p.

Example 2 Polysulfone 259 N-methyA/-2-pyrrolidone 509 Diethylene glyco-1v25g at 30°C
A polypropylene thread serving as a base material was impregnated with the dope solution and then pulled out from the dope solution.

5111/86C air with a temperature of 50℃ and a relative humidity of 90%
Spray it on to gel, then immerse it in water at 30℃,
Let solidify. After coagulating for 2 minutes, it was thoroughly washed with water and dried.

The obtained hollow fiber has a pore size of approximately 0.05 μm and a water permeability of 5 m1.
It was 7°i, 4 at 70m.

Effects of the Invention As described above, the present invention provides a hollow fiber for filtration that is easy to control the pore diameter, can be manufactured with a simple manufacturing equipment, is easy to operate and handle, and has excellent productivity. Since it can provide a manufacturing method, its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a manufacturing apparatus of the present invention, and FIG. 2 is a sectional view of a hollow fiber for filtration according to the present invention. 1...Base material 2...Microporous membrane 3...Empty@
4... Ink pan 5... Dope liquid
6...Gelification chamber 7...-Fire and water washing tank 8.
... Shower 9 ... Secondary washing tank 10 ... Drying room 11 ... Winding machine Yuasa Battery Co., Ltd.

Claims (1)

[Claims] A hygroscopic solvent is added to a solution in which a polymeric material is dissolved to form a mixed solution, and after impregnating the thread that will serve as a base material with the solution, the solution attached to the base material is pulled up and turned into a hygroscopic gel, and then contacted with a non-solvent. A method for producing a hollow fiber for filtration, characterized in that the hollow fiber has straight micropores.