JP2014136183A - Method of manufacturing hollow fiber membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of easily manufacturing a hollow fiber membrane having an even thickness.SOLUTION: A method of manufacturing a hollow fiber membrane includes a process of discharging a resin solution from a mold having a discharge port and coagulating it in a coagulation vessel containing a nonsolvent. The mold includes an inner tube which discharges a coagulation liquid to the coagulation vessel from the discharge port, an outer tube which discharges the resin solution to the coagulation vessel from the discharge port, and a core material which is at least partially inserted into the discharge port of the inner tube. The core material is arranged so that a center of a cross section of the core material corresponds to a center of a cross section of the discharge port of the inner tube.

Description

  The present invention relates to a method for producing a hollow fiber membrane.

  Conventionally, in water purification such as clarification of river water and groundwater, clarification of industrial water, drainage and sewage treatment, pretreatment for seawater desalination, etc., a water treatment device provided with a polymer water treatment membrane has been used. The polymer water treatment membrane used in this water treatment apparatus often uses a hollow fiber-like porous membrane (hereinafter also referred to as “hollow fiber membrane”) formed of a polymer material. This is because the hollow fiber membrane has high performance for separating various components contained in the water to be treated.

  This hollow fiber membrane has a straw-like form and is usually produced using a double mold. The double die is literally a double cylindrical die having a hollow inside, and has a double round cross section. Hereinafter, the inner tube of the double mold is referred to as an “inner tube”, and the tube surrounding the outer side at a certain distance from the inner tube is referred to as an “outer tube”. As shown in Patent Document 1 (Japanese Patent Laid-Open No. 4-343707), a hollow fiber membrane using a double mold is produced by flowing a solid component resin solution into an outer tube in a water tank in which a coagulating liquid is stored. This is done by flowing a coagulation liquid through the inner tube.

  By the way, in recent years, it has been required to supply water more efficiently and more economically. In order to meet this need, hollow fiber membranes having a larger diameter than those in the past are being developed. The large-diameter hollow fiber membrane has an advantage of high performance for separating various components contained in the water to be treated and also has a high treatment speed for the water to be treated.

JP-A-4-343707

  In the production method described in Patent Document 1, a hollow fiber membrane having a conventional diameter can be produced, but a hollow fiber membrane can be stably produced even if an attempt is made to produce a hollow fiber membrane having a large diameter that has recently been required. could not. Specifically, in order to produce a hollow fiber membrane with a large diameter, when the diameter of each pipe of the double mold is increased, the hollow fiber membrane has thin and thick portions, or the hollow fiber membrane surface As a result, the hollow fiber membrane could not be stably produced.

  This invention is made | formed in view of the said present condition, The place made into the objective is to provide the method of manufacturing simply the hollow fiber membrane of uniform thickness.

  The present inventors investigated the cause of the unstable production of the large-diameter hollow fiber membrane, and increased the supply cross-sectional area of the solution in each tube of the double mold, so that the supply of coagulating liquid (or resin solution) It has been found that the problem is that the supply pressure becomes non-uniform because the pressure becomes locally weaker or stronger. Such a problem should not be a problem in the production of hollow fiber membranes having an inner diameter of about 0.1 mm as in the prior art, because the liquid supply cross section is small, and is unique only when producing a large-diameter hollow fiber membrane. It is a problem. In order to solve the problem, the inventors of the present invention have completed the present invention shown below by diligently studying to reduce the melt supply cross section when discharging from a double mold.

[1] A method for producing a hollow fiber membrane comprising a step of discharging and solidifying a resin solution from a mold having a discharge port in a coagulation tank containing a non-solvent,
The mold includes an inner tube that discharges the coagulation liquid from the discharge port to the coagulation tank, an outer tube that discharges the resin solution from the discharge port to the coagulation tank, and the discharge port of the inner tube. A core material at least partially inserted,
The said core material is arrange | positioned so that the center of the cross section of the said core material may correspond with the center of the cross section of the discharge port of the said inner tube, The manufacturing method of the hollow fiber membrane characterized by the above-mentioned.
[2] The method for manufacturing a hollow fiber membrane according to [1], wherein the core material is a cylinder extending in a discharge direction from the discharge port.
[3] The method for manufacturing a hollow fiber membrane according to [1], wherein the core material is a truncated cone, and the truncated cone is arranged so that a cross-sectional area increases from the discharge port toward a discharge direction.

  According to the method for producing a hollow fiber membrane of the present invention, a hollow fiber membrane having a uniform thickness can be easily produced.

3 is a schematic cross-sectional view showing an example of a method for producing the hollow fiber membrane of Embodiment 1. FIG. 6 is a schematic cross-sectional view showing an example of a method for producing a hollow fiber membrane according to Embodiment 2. FIG.

  The method for producing a hollow fiber membrane of the present invention is a method utilizing a phase separation method, particularly a non-solvent induced phase separation method, and a resin solution is discharged from a mold having a discharge port in a coagulation tank containing a non-solvent. And a solidifying step, and the step is performed in a state in which the core material is inserted into the discharge port of the inner tube.

<Embodiment 1>
(Process to discharge and solidify the resin solution from the mold with the discharge port)
In this embodiment, this process is performed using the coagulation tank 10 shown in FIG. The double-pipe structure mold includes an inner tube 12 for discharging the coagulating liquid 14 from the discharge port to the coagulation tank 10, an outer tube 11 for discharging the resin solution 15 from the discharge port to the coagulation tank 10, and an inner tube from the discharge port. 12 and a core material 13 at least partially inserted. A coagulating liquid 14 is supplied to the inner pipe 12 having a double pipe structure, and a resin solution 15 is supplied to the outer pipe 11. On the other hand, the coagulation tank 10 is usually filled with a non-solvent 16. Then, by discharging the resin solution 15 into the coagulation tank 10 filled with the non-solvent 16, the resin solution 15 is solidified to form a hollow fiber membrane. By winding up the hollow fiber membrane thus produced, the hollow fiber membrane produced in the present embodiment can be obtained.

  In the present embodiment, the above process is performed in a state where a cylindrical core material is inserted into the discharge port of the inner tube. By inserting the core material 13 at this position, the cross-sectional area of the discharge port of the inner tube 12 from which the coagulating liquid 14 is discharged can be reduced by the cross-sectional area of the core material 13, thereby discharging the coagulating liquid. Becomes easier to stabilize. When the discharge of the coagulating liquid is stabilized, the thickness of the obtained hollow fiber membrane tends to be uniform, and the hollow fiber membrane can be stably produced. The uniform thickness of the hollow fiber membrane increases the mechanical strength and water permeability of the hollow fiber membrane. In addition, by disposing the core material 13 at the discharge port of the inner tube, it is possible to reduce the supply amount of the coagulating liquid by the cross-sectional area of the core material 13.

(Core material)
In this embodiment, a cylindrical core material 13 extending in the direction of discharging the resin solution is used (that is, either the top surface or the bottom surface of the core material is inserted into the discharge port of the inner tube). The shape is not limited to a cylindrical shape, and may be an elliptical prism shape, a triangular prism shape, a quadrangular prism shape, a pentagonal prism shape, or a pyramid shape such as a cone, a triangular pyramid, a quadrangular pyramid, or a pentagonal pyramid. It may be a frustum type such as a truncated cone type, a triangular frustum type, or a quadrangular frustum type. From the viewpoint that the inside of the hollow fiber membrane can be easily approximated to a perfect circle, the core material 13 is more preferably a cylindrical shape, a conical shape, or a truncated cone shape. In the second embodiment to be described later, the case where the core 13 is a truncated cone will be described in detail. However, when a truncated cone-shaped core is used, the core is gradually cut in the direction in which the resin solution is discharged. It is preferable to arrange so as to increase the area.

  Regarding the arrangement of the core material 13 in the inner pipe, it is preferable that the center of the cross section of the core material 13 is arranged so as to coincide with the center of the cross section of the discharge port of the inner pipe 12. That is, it is preferable that the columnar, conical or frustum-shaped core material is disposed concentrically or coaxially with the inner tube. By disposing the core member 13 in this way, it is possible to make the hollow fiber membrane closer to a perfect circular shape and to manufacture a product with a more uniform thickness. Here, “the center of the cross section” is used in the same meaning as the center of gravity of the cross section.

  Further, the core material may be inserted into the discharge port of the double-pipe structure mold, but is not limited thereto, and one end of the core material is on the same plane as the plane formed by the discharge port. There is no problem even if there is. The arrangement position of the core material is not particularly limited as long as the core material is arranged so as to reduce the discharge section of the discharge port. If the distance between the discharge port of the inner pipe and one end of the core material is defined, one end of the core material is preferably inserted from 0 mm to 30 mm from the plane formed by the discharge port, more preferably from 5 mm to 10 mm. It is inserted. Within this range, the discharge cross-sectional area of the inner tube can be effectively reduced, and the hollow fiber membrane can be produced more stably.

The diameter of the core material 13 is preferably smaller than the diameter of the inner tube 12. When the diameter of the core material 13 is equal to or larger than the diameter of the inner tube, the core material 13 covers the entire cross section of the inner tube, and thus it becomes difficult to supply the coagulating liquid 14 to the coagulation tank 10. Sometimes. The ratio (D _s / D _u ) of the diameter (D _s ) of the core material to the diameter (D _u ) of the inner tube is from the viewpoint of making the supply cross-sectional area of the coagulating liquid smaller and making the supply of the coagulating liquid more stable. 0.1 or more, more preferably 0.4 or more, and still more preferably 0.5 or more. On the other hand, D _s / D _u is preferably 0.9 or less, more preferably 0.8 or less, and still more preferably 0.8 from the viewpoint of securing a certain cross-sectional area of the coagulating liquid. 75 or less.

The ratio (D _g / D _u ) of the diameter (D _s ) of the core material to the diameter (D _g ) of the outer tube is such that the core material does not interfere with the outflow path of the resin solution and stably winds the hollow fiber membrane. From the viewpoint of making it, it is preferably 0.2 or more and 0.7 or less, more preferably 0.3 or more and 0.6 or less. When _Dg / _Du is 0.2 or more, the cross-sectional area of the core material can be secured to some extent, and the effect of stabilizing the discharge of the coagulating liquid can be sufficiently obtained. On the other hand, when D _g / D _u is 0.7 or less, both the resin solution and the coagulating liquid supply portion are less likely to enter and disturb each other, and the production of the hollow fiber membrane can be further stabilized.

  The length of the core material is preferably 0.1 mm or more and 500 mm or less, more preferably 1 mm or more and 300 mm or less, and further preferably 5 mm or more and 100 mm or less. Further, the cross-sectional diameter of the core material is preferably 0.5 mm or more and 10 mm or less, more preferably 1 mm or more and 8 mm or less, and further preferably 2 mm or more and 6 mm or less. If it exceeds 500 mm, the core material and the hollow fiber membrane come into contact with each other, and the shape of the hollow fiber membrane is difficult to stabilize.

(Resin solution)
Any material may be used for the resin solution used in the above step as long as it contains a substantially single resin. “Substantially single” means substantially single, that is, one main constituent material, specifically, one resin is 50% by weight or more, preferably 60% by weight or more, More preferably, it means 70% by weight or more. In addition, it is intended that the single material and the single main constituent material do not include additives usually used in the production of the resin or in the production of the hollow fiber membrane described later.

  As the substantially single material, materials / materials generally used in the field can be used. For example, polysulfone (PS), polyethersulfone (PES), polyvinylidene fluoride (PVDF) , Polyethylene (PE), cellulose acetate (CA), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyimide (PI), polyvinyl chloride, cellulose (cellulose acetate), cellulose acetate Etc.) and the like. Among these, a vinyl chloride resin is preferable. You may use these individually or in combination of 2 or more types.

  As vinyl chloride resin, vinyl chloride homopolymer (vinyl chloride homopolymer), copolymer of copolymerizable unsaturated bond monomer and vinyl chloride monomer, and graft copolymerized with vinyl chloride monomer. Examples thereof include a graft copolymer and a (co) polymer composed of those chlorinated vinyl chloride monomer units. These may be used alone or in combination of two or more. In particular, in order to improve stain resistance, it is suitable that a hydrophilic monomer is copolymerized.

  In order to improve moldability, heat stability, etc., the resin solution may be used alone or in combination of two or more lubricants, heat stabilizers, film forming aids and the like. Examples of the lubricant include stearic acid and paraffin wax. Examples of the thermal stabilizer include tin-based, lead-based, and Ca / Zn-based stabilizers that are generally used for molding a vinyl chloride resin. Examples of the film forming aid include hydrophilic polymers such as polyethylene glycol and polyvinyl pyrrolidone having various polymerization degrees.

  The solvent used for the resin solution is not particularly limited as long as it is soluble in the resin, and usually the solvent used when synthesizing the resin can be used. When a vinyl chloride resin is used as the resin, for example, dimethyl sulfoxide, N, N-dimethylformamide, tetrahydrofuran, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like can be mentioned. A mixture of seeds or more can be used.

  In the resin solution, the ratio of the resin component to the total weight of the resin solution is preferably 15% by weight or more, more preferably 20 to 40% by weight, and further preferably 20 to 30% by weight. By setting this range, the phase separation can be accelerated moderately, the strength of the hollow fiber membrane can be sufficiently secured, and the short-term strength and fatigue strength are remarkably improved when a large-diameter hollow fiber membrane is formed. be able to.

  The viscosity of the resin solution is, for example, preferably 500 to 4000 mPa · s, and more preferably 1000 to 3000 mPa · s. By having such a viscosity, the roundness of the outer shape of the hollow fiber membrane can be secured, and thus a membrane having a uniform thickness and film thickness can be produced. As the viscosity, a value measured using a vibrating viscometer (manufactured by Seconic Corporation, VM-100A-M) after directly introducing the resin solution into the sample tube is adopted.

(Coagulation liquid)
The coagulating liquid 14 supplied to the inner tube is preferably water or a solvent mainly composed of water, although a suitable material varies depending on the composition of the resin contained in the resin solution. The coagulation liquid 14 may be the same as the non-solvent 16 filled in the coagulation tank 10.

(Non-solvent)
Since the non-solvent 16 in the coagulation tank 10 is in direct contact with the resin solution, like the coagulation liquid 14, it is preferable to use water or a solvent mainly composed of water. The non-solvent preferably has a difference between the temperature of the resin solution discharged from the discharge port and the temperature of the non-solvent of 100 ° C. or less. As a result, it is possible to prevent clogging in the vicinity of the discharge port of the spinning die due to a rapid temperature drop of the resin solution and a sudden increase in the viscosity of the resin solution. Further, by keeping the temperature of the non-solvent constant, the phase separation behavior of the resin solution can be stably maintained, and performance such as water permeability and strength can be stably expressed.

(Hollow fiber membrane)
The hollow fiber membrane manufactured by this embodiment has an outer diameter of 3.6 mm or more and 10 mm or less. The wall thickness of the hollow fiber membrane can be 0.15 to 2.4 mm, and preferably 0.2 to 2.4 mm. Moreover, it is preferable that the internal diameter of a hollow fiber membrane is 3.2 mm or more. The measured value using an electron micrograph shall be employ | adopted for the internal diameter and thickness of a hollow fiber membrane.

  The strength of the hollow fiber membrane is usually determined by various factors such as the material, outer diameter, thickness, roundness, internal structure, etc. Among them, the SDR value (outer diameter / thickness ratio) is used. The SDR value of the hollow fiber membrane is preferably 3.6 to 34. When the SDR value is 34 or less, the pressure resistance of the hollow fiber membrane is 0.3 MPa or more, and when the SDR value is 3.6 or more, it is easy to secure a membrane filtration area in the water treatment module. The SDR value is more preferably 4.0 or more and 20 or less, and further preferably 5.0 or more and 16 or less. In particular, when the outer diameter is about 5 to 7 mm, the SDR value is preferably 4 to 16, and more preferably 6.5 to 11.

  The hollow fiber membrane produced by the production method of the present embodiment can usually be a porous membrane having a large number of micropores on its surface. The average pore diameter of the fine pores is, for example, about 0.001 to 10 μm, preferably about 0.01 to 1 μm. The size and density of the pores on the membrane surface can be adjusted as appropriate according to the above-mentioned inner diameter, thickness, characteristics to be obtained, and the like, but it is preferable that the permeated water amount described later can be realized.

  The porosity of the hollow fiber membrane is, for example, about 10 to 90%, preferably about 20 to 80%. The porosity here means the ratio of the total area of the pores to the total area of the hollow fiber membrane in an arbitrary cross section (the cross section in the radial direction of the hollow fiber membrane, the same applies hereinafter), and a micrograph of the membrane cross section It can be calculated from the value of each area.

  In the cross section in the radial direction of the hollow fiber membrane, the porosity with respect to the cross-sectional area of the hollow fiber membrane is preferably about 30 to 85%, and is preferably 50 to 85%, 40 to 75%, or 50 to 75%. More preferred. In addition, it is preferable that the innermost layer, the inner layer, the outer layer, and the pores constituting the outermost layer are distributed in layers from the center to the radial direction. This makes it possible to maintain the strength of the entire membrane by dispersing the stress concentration when an internal pressure / external pressure is applied to the hollow fiber membrane while maintaining water permeability.

The hollow fiber membrane obtained by the production method of this embodiment has a permeated water amount of about 100 L / (m ² · h) or more and about 200 L / (m ² · h) or more at a transmembrane differential pressure of 100 kPa. It is suitable, and about 600 L / (m ² · h) or more can be realized. Also, the internal pressure strength of the film can be about 0.3 MPa or more, about 0.5 MPa or more, and further about 1.0 MPa or more.

Further, the external pressure strength of the film can be about 0.1 MPa or more, about 0.3 MPa or more, and further about 0.7 MPa or more. In particular, the amount of permeated pure water at a transmembrane differential pressure of 100 kPa is about 100 L / (m ² · h) or more, the internal pressure resistance of the film is about 0.3 MPa or more, and the external pressure resistance is about 0.1 MPa or more. Can do.

(Use of hollow fiber membrane)
Since the hollow fiber membrane produced by the production method of the present embodiment has a uniform and uniform thickness, it has an excellent balance between the amount of permeated water and physical strength. For this reason, it is suitable for separation membranes, ultrafiltration (UF) membranes and microfiltration (MF) membranes of existing water treatment equipment, and water treatment for the purpose of water purification, especially water treatment of high-concentration wastewater. It becomes possible.

<Embodiment 2>
The manufacturing method of the hollow fiber membrane of this embodiment is the same as that of Embodiment 1 except that the shape of the core material is different from that of Embodiment 1. That is, in this embodiment, as shown in FIG. 2, a hollow fiber membrane is produced using a truncated cone-shaped core material. The frustoconical core material is arranged so that the diameter of the cross section gradually increases from the discharge port in the discharge direction. For this reason, a hollow fiber membrane having an inner diameter larger than the diameter of the outer tube of the double mold, that is, a hollow fiber membrane having a larger diameter can be produced.

  Of the two circular surfaces constituting the truncated cone type, the circular surface having the smaller cross-sectional area is defined as the “upper surface”, and the circular surface having the larger cross-sectional area is defined as the “bottom surface”. It is preferable to insert the upper surface of the mold into the discharge port of the inner tube. Moreover, it is preferable that the diameter of an upper surface is 0.5 mm or more and 5 mm or less, More preferably, it is 1 mm or more and 3 mm or less. The diameter of the bottom surface is preferably 1 mm or more and 10 mm or less, more preferably 3 mm or more and 8 mm or less. Further, it is preferable that the side surface of the truncated cone shape is so gentle that the taper can follow the flow of the resin solution.

<Other embodiments>
For the first and second embodiments, the above process may be performed by providing an air layer between the discharge port of the double-pipe mold and the non-solvent. The air layer here is provided in order to prevent the discharge port of the double mold and the non-solvent from coming into direct contact with each other. Can be removed. In short, the air layer is provided in order to avoid an unstable state at the beginning of discharge of the resin solution. Therefore, once the production of the hollow fiber membrane is stabilized, it may be removed thereafter. By providing such an air layer, it is possible to prevent the resin solvent from adhering to the discharge port before starting the production and causing streaks to form on the membrane surface of the hollow fiber membrane.

  Hereinafter, the manufacturing method of the hollow fiber membrane of this invention is demonstrated in detail based on an Example. In addition, this invention is not limited only to these Examples. Moreover, the compounding quantity in an Example is shown on a weight basis unless there is particular notice.

Example 1
The resin solution was prepared by mix | blending each component shown in the column of Example 1 of Table 1 mentioned later. Next, the double-pipe structure mold was submerged in the coagulation liquid tank, and the direction of the mold was adjusted so that the spinning direction of the membrane was parallel to the water surface of the coagulation tank. The diameter of the outer tube of the mold was 6.0 mm, and the diameter of the inner tube of the mold was 4.0 mm. The center of one side of a cylindrical core member having a diameter of 3.0 mm and a length of 6 mm was inserted into the center of the cross section of the discharge port of the inner pipe of the mold and screwed to the inner pipe.

  Thereafter, in the coagulation bath, the resin solution adjusted to 40 ° C. was supplied to a double-pipe structure mold at 120 g / min, and at the same time, pure water was supplied as an internal coagulation solution at 100 g / min. Thus, the hollow fiber membrane was produced by coagulating the resin solution in the coagulation liquid tank, and was continuously taken up by a take-up machine installed on the downstream side of the coagulation liquid tank. The resulting hollow fiber membrane had an inner diameter of 4.1 mm.

(Examples 2 to 4)
Compared to Example 1, the components of the resin solution were different as shown in Table 1 above, and the production conditions of the hollow fiber membrane were different as shown in Table 2 below, and the same procedure as in Example 1 was performed. The hollow fiber membranes of Examples 2 to 4 were produced.

(Comparative Examples 1-4)
The hollow fiber membrane of Comparative Examples 1-4 was produced with the manufacturing method similar to Example 1-4 except that the core material was not arrange | positioned with respect to Examples 1-4. In addition, each comparative example number respond | corresponds to each example number, for example, the comparative example 1 differs in having eliminated the core material in manufacture of Example 1, and is a hollow fiber on the manufacturing conditions similar to Example 1. A membrane was prepared.

  In Table 2, since the core material of the examples (Examples 2 and 4) has a truncated cone shape, the upper surface diameter (minimum diameter) and the bottom surface diameter (maximum diameter) are described as “minimum diameter / maximum diameter”. .

(Performance evaluation results)
With respect to the hollow fiber membranes obtained in the respective Examples and Comparative Examples, the pressure resistance performance and water permeability performance were evaluated, and the inner diameter (mm) and SDR of the hollow fiber membranes were measured. The results are shown in Table 3.

  Each value (internal pressure and external pressure) of “pressure resistance” in Table 3 is known after inserting a metal tube having a diameter of 4.6 mm at both ends of the hollow fiber membrane and connecting the insertion portions with crimped joints. The internal pressure / external pressure was gradually increased at a rate of 0.1 MPa / sec using a test pump for pressure resistance test of the pipe, and the pressure value (MPa) at the moment when the hollow fiber membrane was broken was measured. It shows that external pressure strength is excellent, so that each pressure value is high.

“Permeability” in Table 3 indicates the water permeability (unit of water permeability: L / hr · Aatm) of pure water of the polymer water treatment membrane by an internal pressure test under the conditions of 25 ° C. and a transmembrane pressure difference of 50 kPa. It was calculated by doing. It shows that it is excellent in the water permeability of a hollow fiber membrane, so that the value of water permeability is high.
In Table 3, “inner diameter” and “SDR” measure the inner diameter, outer diameter, and wall thickness based on an electron microscope observation image of the cross section of the hollow fiber membrane. It was calculated by the diameter (outer diameter / wall thickness).
In addition, each value of the internal pressure in Table 3, an external pressure, water permeability performance, and an internal diameter measures five different places of the hollow fiber membrane of each Example and each comparative example, and when the measurement value of 5 times is substantially the same, When the average numerical value was varied five times, the range from the maximum value to the minimum value was indicated.

(Discussion)
The hollow fiber membranes of Examples 1 to 4 had the same value at five locations where the pressure resistance, water permeability and inner diameter differed, whereas those of Comparative Examples 1 to 4 were pressure resistance, water permeability and inner diameter. The measured values varied at five different points. Moreover, the hollow fiber membranes of Examples 1 to 4 were superior to those of Comparative Examples 1 to 4 in both pressure resistance and water permeability. These results are considered to be due to the fact that the hollow fiber membranes of Examples 1 to 4 have a uniform thickness as compared with those of Comparative Examples 1 to 4. From the above results, it was clarified that a hollow fiber membrane having a uniform thickness can be easily produced by providing a core material at the center of the inner tube to produce a hollow fiber membrane, and the effect of the present invention was shown.

  The present invention is used for water purification such as pretreatment for river water and groundwater clarification, industrial water clarification, drainage and sewage treatment, seawater desalination regardless of the aspect of the water treatment apparatus, etc. It can be widely used like a water treatment membrane, a microfiltration membrane, etc., and can be used particularly advantageously for MBR.

10, 20 Coagulation tanks 11, 21 Outer tube 12, 22 Inner tube 13, 23 Core rod 14, 24 Coagulation solution 15, 25 Resin solution 16, 26 Non-solvent

Claims (3)

In a coagulation tank containing a non-solvent, a method for producing a hollow fiber membrane comprising a step of discharging and solidifying a resin solution from a mold having a discharge port,
The mold includes an inner tube that discharges the coagulation liquid from the discharge port to the coagulation tank, an outer tube that discharges the resin solution from the discharge port to the coagulation tank, and the discharge port of the inner tube. A core material at least partially inserted,
The said core material is arrange | positioned so that the center of the cross section of the said core material may correspond with the center of the cross section of the discharge port of the said inner tube, The manufacturing method of the hollow fiber membrane characterized by the above-mentioned.   The method for producing a hollow fiber membrane according to claim 1, wherein the core material is a cylinder extending in the discharge direction from the discharge port. The core is a truncated cone;
The method of manufacturing a hollow fiber membrane according to claim 1, wherein the truncated cone is disposed so that a cross-sectional area increases from the discharge port toward a discharge direction.