JP2014240041A - Hollow fiber membrane and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane where water permeability and strength are balanced, both water permeability and strength are excellent, water treatment efficiency is enhanced in the hollow fiber membrane having a large diameter so as to correspond to various kinds of water to be treated and to provide a production method of the same.SOLUTION: In a hollow fiber membrane obtained by the non-solvent induced phase separation of a polymer compound solution containing a polymer compound and a solvent: 0.1-10 wt.% inorganic compound to the polymer compound is contained; a self-supporting structure where an outside diameter is 3.6-10 mm, an SDR value being a ratio of an outside diameter to a thickness is 5.8-34 and an inside diameter is 3.2 mm or more is possessed; and a separation function is possessed on both surfaces.

Description

  The present invention relates to a large-diameter hollow fiber membrane and a method for producing the same.

Conventionally, hollow fiber membranes have been used for water purification, for example, clarification of river water and groundwater, clarification of industrial water, drainage and sewage treatment, pretreatment for seawater desalination, and the like.
Such a hollow fiber membrane is usually used as a separation membrane in a water treatment apparatus. For example, polysulfone (PS), polyvinylidene fluoride (PVDF), polyethylene (PE), cellulose acetate (CA) Hollow fiber-like porous membranes made of various polymer materials such as polyacrylic acid, polyacrylonitrile (PAN), polyvinyl alcohol (PVA), and polyimide (PI) are used.

  In order to manufacture a hollow fiber-like porous membrane made of such various materials with dense pores and high water permeability, for example, a mixture in which a filler such as silica is added to a thermoplastic resin, Thermally induced phase separation using a solvent is used (for example, Patent Documents 1 and 2).

JP 2004-41835 A JP 2005-15535 A

However, when a filler is added to the thermoplastic resin, the water permeability is improved, but the resin becomes brittle and the strength of the hollow fiber membrane to be obtained may be lowered, and a balance between the water permeability and the strength is required.
In addition, when thermally induced phase separation is performed using a mixture of a resin containing a filler and a solvent, a step of extracting or removing the filler is required thereafter, and the method for producing a hollow fiber membrane is complicated. there were.

On the other hand, for hollow fiber membranes used for water treatment, hollow fiber membranes having a relatively large diameter that can be used for various types of water to be treated have been proposed by using activated sludge. If the thread membrane has the ability to filter and remove smaller foreign substances, that is, the filtration capacity is increased to the ultrafiltration membrane level, the pure water permeation amount decreases, and conversely, if the pure water permeation amount is increased, the filtration capacity is limited. There may be a microfiltration membrane level that is relatively lower than that of the outer filtration membrane. That is, there is a trade-off relationship between the filtration capacity and the amount of pure water permeation. Therefore, there is a problem that a large facility is required in order to secure both a high filtration capacity and a sufficient water permeability.
Under such circumstances, there is a demand for a hollow fiber membrane that can achieve both high filtration capacity and sufficient water permeability in a hollow fiber membrane having a relatively large diameter.

  The present invention has been made in view of the above problems, and in a large-diameter hollow fiber membrane that can be used for various types of water to be treated, the water permeability, strength, and filtration ability are balanced, It aims at providing the hollow fiber membrane which was excellent in both performance and intensity | strength, and filtration capability, and improved water treatment efficiency, and its manufacturing method.

The present invention is shown below.
[1] A hollow fiber membrane obtained by non-solvent induced phase separation of a polymer compound solution containing a polymer compound and a solvent,
Containing 0.1 to 10% by weight of an inorganic compound with respect to the polymer compound;
It has a self-supporting structure with an outer diameter of 3.6 to 10 mm, an SDR value of 5.8 to 34, which is the ratio of outer diameter to wall thickness, and an inner diameter of 3.2 mm or more, and has a separation function on both sides. Hollow fiber membrane.
[2] The hollow fiber membrane as described above, wherein the inorganic compound is a fine particle having an average primary particle diameter of 10 μm or less, or a fibrous compound having a fiber diameter of 5 to 50 μm and a fiber length of 200 μm or less.
[3] The hollow fiber membrane according to any one of the above, having a fractionation property of an ultrafiltration membrane or a microfiltration membrane.
[4] The internal pressure strength of the film is 0.3 MPa or more,
The hollow fiber membrane according to any one of the above, wherein the external pressure strength is 0.1 MPa or more and the water permeability of pure water is greater than 400 L / m ² · hr · atm.
[5] preparing a solution of the polymer compound,
An inorganic compound is mixed in the polymer compound solution at 0.1 to 10% by weight with respect to the polymer compound,
The obtained polymer compound solution is discharged into a non-solvent to cause non-solvent induced phase separation,
Hollow fiber membrane having a self-standing structure with an outer diameter of 3.6 to 10 mm, an SDR value of 5.8 to 34, which is a ratio of outer diameter to wall thickness, and an inner diameter of 3.2 mm or more, and having a separation function on both sides A process for producing a hollow fiber membrane, characterized in that
[6] The polymer compound solution is immersed in a coagulation tank containing the non-solvent from a state where the polymer compound solution is discharged from a mold having a discharge port into the air, and the polymer compound solution is The method for producing a hollow fiber membrane as described above, which is solidified.

The hollow fiber membrane of the present invention has a balance between water permeability and strength and filtration capacity, and can be excellent in all of water permeability, strength and filtration capacity while having a large diameter.
Further, according to the method for producing a hollow fiber membrane of the present invention, a hollow fiber membrane having a large diameter and excellent in water permeability, strength and filtration ability can be produced by a simple and easy method.

  The hollow fiber membrane of the present invention is a hollow fiber membrane mainly composed of a polymer compound, and contains a predetermined amount of an inorganic compound with respect to the polymer compound.

  Polymer compounds include vinyl chloride, polysulfone (PS), polyvinylidene fluoride (PVDF), polyolefins such as polyethylene (PE), cellulose acetate (CA), polyacrylonitrile (PAN), polyether High molecular compounds such as sulfone, polyvinyl alcohol (PVA), and polyimide (PI) are listed. You may use these individually or in combination of 2 or more types. Of these, vinyl chloride resins are preferred. As these materials, any materials such as those commercially available and those obtained by polymerization from various monomers by a known method can be used. The number average molecular weight and the like of the polymer compound is preferably adjusted as appropriate according to the type.

Examples of vinyl chloride resins include vinyl chloride homopolymers, copolymers of monomers having unsaturated bonds copolymerizable with vinyl chloride monomers and vinyl chloride monomers, and graft copolymers obtained by graft copolymerization of vinyl chloride monomers to polymers. Examples thereof include polymers and (co) polymers composed of chlorinated vinyl chloride monomer units. These may be used alone or in combination of two or more. In particular, it is preferable that a hydrophilic monomer is copolymerized in order to improve stain resistance.
As the monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer, the polymer to be graft copolymerized with vinyl chloride, and the hydrophilic monomer, for example, those described in WO2011 / 108579 can be used. The polymer compound may contain a crosslinkable monomer. As the crosslinkable monomer, those described in WO2011 / 108579 can be used.

  Examples of the inorganic compound include silica, calcium silicate, aluminum silicate, calcium carbonate, magnesium carbonate, calcium phosphate, iron, zinc and other metal oxides or hydroxides, sodium, potassium, calcium and other salts, glass fibers, and the like. . These inorganic compounds may or may not be subjected to surface treatment using various treatment agents.

  The inorganic compound is preferably contained in an amount of 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, even more preferably 0.5 to 2% by weight based on the total weight of the polymer compound. By setting it as content of such a range, it can prevent that an inorganic compound aggregates in the solution of the high molecular compound mentioned later, and can be set as a uniform solution. As a result, a uniform hollow fiber membrane can be produced and its strength can be improved.

  The shape of the inorganic compound is not particularly limited, and examples thereof include particles, flakes, and fibers. Regardless of the shape, the maximum length is preferably about 200 μm or less, more preferably about 100 μm or less, and further preferably about 80 μm or less. Particularly, in the case of a fiber or flake, the length is about 30 to 200 μm, preferably about 30 to 100 μm, and the diameter (width) is about 5 to 50 μm, preferably about 5 to 30 μm. In the case of particles, the average primary particles are about 10 μm or less, preferably about 5 μm or less, more preferably about 1 μm or less.

  In consideration of improvement in moldability and strength of the hollow fiber membrane, it is preferable that the inorganic compound is uniformly dispersed in the solvent described later.

  As described above, the hollow fiber membrane of the present invention contains an inorganic compound in the polymer compound constituting the hollow membrane, so that a micro space is positively generated between the inorganic compound and the resin, and the filtration resistance is increased. By reducing, water permeability can be improved. In particular, a large-diameter hollow fiber membrane such as the present invention is expected to be disadvantageous when the water permeability is simply compared with a small-diameter hollow fiber membrane due to an increase or decrease in surface area. By inclusion, even if the hollow fiber membrane has a large diameter, and even if the filtration performance of the hollow fiber membrane is high, water permeability can be further ensured.

The hollow fiber membrane of the present invention has an outer diameter of 3.6 mm to 10 mm, an SDR value that is a ratio of the outer diameter to the wall thickness of 5.8 to 34, and an inner diameter of 3.2 mm or more.
Especially, it is preferable that an outer diameter is about 3.6 mm-7 mm, SDR value is 6.5-11, and an internal diameter is 3.2 mm or more. Further, it is more preferable that the outer diameter is about 5.3 mm to 7 mm, the SDR value is 6.5 to 11, and the inner diameter is 3.2 mm or more. As a result, while maintaining the strength when an internal pressure and an external pressure are applied to the hollow fiber membrane, it is possible to ensure an inner diameter that is large enough not to block the hollow fiber membrane even when high-concentration wastewater is passed through. It becomes possible.
The inner and outer diameters, thickness, etc. of the film can be measured by actual measurement using an electron micrograph or the like.

This hollow fiber membrane has a self-supporting structure.
Generally, a material with low strength has a desired shape, for example, a cylindrical shape, a tube shape, etc. unless it is a composite with a support made of a stronger material (nonwoven fabric, paper, metal, ceramic, etc.). With a support that does not have a separation function provided by a hollow fiber membrane such as a cylindrical ceramic or a non-woven fabric formed into a cylindrical shape so that a desired shape can be maintained in addition to the material forming the membrane because it cannot be maintained. Yes.
In contrast, the present invention has a self-supporting structure that can maintain a desired shape without a support body that does not change a desired shape such as a cylindrical shape, that is, in a support-free state.

The hollow fiber membrane has a separation function on both sides. Therefore, it is a porous film having a large number of micropores on the surface. The average pore diameter of the fine pores can be appropriately adjusted depending on the application, that is, the type of water to be treated to be described later, and is, for example, about 0.001 to 10 μm, preferably about 0.001 to 1 μm, more preferably 0. About 0.001 to 0.1 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, etc. Is suitable. Such fine pores can serve as a water treatment membrane.
Moreover, the fractionation property of an ultrafiltration membrane or a microfiltration membrane (preferably ultrafiltration membrane) can be adjusted by the size and density of the micropores, for example. In general, an ultrafiltration membrane having a pore size of about 2 to 200 nm or a fractional molecular weight of 300,000 Da or less is suitable, preferably 150,000 Da or less, and a microfiltration membrane is a membrane of about 50 nm to 10 μm. It is known that
Therefore, the separation function here means a higher separation function than microfiltration, for example, ultrafiltration or microfiltration separation function.

The hollow fiber membrane of the present invention is formed by non-solvent induced phase separation (NIPS) of a polymer compound solution containing the above-described polymer compound and a solvent.
In such non-solvent induced phase separation, first, (a) a polymer compound solution is prepared, (b) the polymer compound solution is mixed with an inorganic compound, and (c) the resulting polymer compound solution is non-coated. It can be carried out by discharging into a solvent.

(A) Preparation of polymer compound solution The polymer compound solution only needs to contain one or more of the above-described polymer compounds.

The polymer compound solution may be blended with additives such as a lubricant, a thermal stabilizer, and a film forming aid for the purpose of improving moldability and heat stability during film formation. You may use these individually or in combination of 2 or more types. As these additives, for example, those described in WO2011 / 108579 can be used.
In particular, it is preferable to use hydrophilic polymers such as polyethylene glycol and polyvinyl pyrrolidone having various polymerization degrees as a film forming aid.

The solvent used to make the polymer compound into a solution is not particularly limited as long as it is a good solvent for the polymer compound to be used. Usually, the solvent used when synthesizing the polymer compound is used as it is. Can do.
Specific examples of the good solvent include ethylene glycol, glycerin; polyethylene oxide, polypropylene oxide, alkylaryl polyether alcohol, alkylaryl sulfonate, alkyl sulfate, triethyl phosphate, formamide, acetic acid, propionic acid, 2-methoxyethanol, t- Amyl alcohol, methanol, ethanol, propanol, isopropanol, hexanol, heptanol, octanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl ether, ethyl acetate, amyl acetate, diethylene glycol, di (ethylene glycol) diethyl ether, di (ethylene glycol) dibutyl ether And water.
A solvent can be used individually or in mixture of 2 or more types.

In particular, when a vinyl chloride resin is used as the resin, examples of the solvent include dimethyl sulfoxide, N, N-dimethylformamide, tetrahydrofuran, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like. .
Moreover, when using what was mentioned above other than vinyl chloride resin as resin, it can select from the thing illustrated as a good solvent mentioned above as a solvent suitably, and can use it.

  For example, the polymer compound is preferably contained in an amount of 15% by weight or more based on the total weight of the polymer compound, more preferably 20 to 40% by weight, and still more preferably 20 to 30% by weight. By setting it as this range, while being able to speed up phase separation moderately, sufficient intensity | strength can be ensured in the hollow fiber membrane obtained. In addition, even a relatively large-diameter hollow fiber membrane as will be described later can ensure particularly short-term strength and can significantly improve fatigue strength.

From another viewpoint, for example, the viscosity of the polymer compound solution is preferably about 500 to 4000 mPa · s, more preferably about 1000 to 3000 mPa · s. Thereby, stirring of a polymer compound solution can be performed easily and reliably. In addition, aggregation of inorganic compounds can be prevented. Furthermore, the inorganic compound can be uniformly dispersed. In particular, the roundness of the outer shape of the hollow fiber membrane can be reduced in the production line without causing the inorganic compound to be biased in the mold that is usually used during the production. And a film having a uniform thickness and thickness can be manufactured.
The viscosity can be a value measured, for example, by directly introducing a solution of a polymer compound into a sample tube and using a vibration viscometer (manufactured by Seconic Corporation, VM-100A-M).

  From another point of view, the solution of the polymer compound is suitable to prepare a specific gravity difference with a non-solvent described later within 1.0, preferably within 0.8, and more preferably within 0.2. . Thereby, it is possible to effectively prevent the membrane itself from floating, sinking or flattening in the coagulation tank during the drawing of the membrane in the manufacturing process of the hollow fiber membrane.

  In preparing a solution of the polymer compound, it is preferable not to raise the temperature excessively in order to prevent volatilization of the solvent and denaturation of the polymer compound, for example, about 80 ° C. or less, 60 ° C. or less, 50 The polymer compound is preferably dissolved in a solvent at a temperature of 0 ° C. or lower, and may be dissolved at room temperature.

(B) Mixing of the inorganic compound into the polymer compound solution The above-described mixing of the inorganic compound into the polymer compound solution is not necessarily performed after the preparation of the polymer compound solution is completed. It may be performed either simultaneously with the addition of the polymer compound to the solvent or before or after the addition. Especially, in order to prevent aggregation of inorganic compound itself, it is preferable to add and mix, after fully dissolving a high molecular compound in a solvent.

(C) Non-solvent-induced phase separation By discharging a solution of a polymer compound containing an inorganic compound into a non-solvent, non-solvent-induced phase separation is performed, and a hollow fiber membrane can be formed.
Here, the non-solvent means a poor solvent.
Specifically, it can be appropriately selected depending on the type of the polymer compound solution described above, but water, a mixed solution of water and the above-described good solvent (in order to control the phase separation rate, the main component is water), Alcohol etc. are mentioned.

  For discharging the polymer compound solution into the non-solvent, a spinning mold is usually used. The spinning die has a discharge port, and the polymer compound solution is discharged from the discharge port. This spinning die is usually provided with a discharge port having a concentric double nozzle shape for spinning a polymer compound solution. Normally, a non-solvent is discharged from the inner nozzle.

The non-solvent is usually filled in a coagulation tank, and non-solvent-induced phase separation is performed in the polymer compound solution by discharging the polymer compound solution into the coagulation tank filled with the non-solvent. A yarn membrane can be formed.
In the coagulation tank, a discharge port of a spinning mold is arranged so as to be able to move into or out of the coagulation tank or from outside to inside so that spinning can be performed in the coagulation tank.
The polymer compound solution may be (1) discharged from a mold having a discharge port immersed in the coagulation tank, or (2) air from a mold having a discharge port disposed on the coagulation tank. The discharged polymer compound solution may be submerged in the coagulation tank, or (3) the discharge port contains a non-solvent from the state where it is discharged into the air from a mold having the discharge port. It may be immersed in a coagulation tank and discharged into the coagulation tank.

In the case of (1), the polymer compound solution first appropriately forms a skin layer by volatilization of the solvent from the surface thereof in the air. Next, liquid-liquid phase separation can be quickly started in a non-solvent, and the resulting hollow fiber membrane can obtain a porous and uniform surface. As a result, excellent water permeability and improved fractionation performance can be realized due to the decrease in filtration resistance.
The discharge of the polymer compound solution in the air is, for example, in the range from the vertical direction (90 ° with respect to the surface of the non-solvent (take-off direction of the film after discharge)) to the same direction as the surface of the non-solvent. It can be adjusted appropriately. In particular, it is preferable to discharge the polymer compound solution in the vertical direction at the start of discharge. Since all of the polymer compound solution hangs down due to its own weight, it is possible to prevent the polymer compound solution that has been cured from interfering with the discharge port.

  In the case of (3), compared to the case where the discharge of the polymer compound solution is started from the state where the mold is submerged in the coagulation tank, the discharge resistance due to the non-solvent is added to the discharge port tip. Therefore, clogging of the polymer compound solution can be avoided, and as a result, deformation of the resulting film can be prevented and a skin layer excellent in fractionation performance can be obtained.

  Since the non-solvent in the coagulation tank is in direct contact with the polymer compound solution, the difference between the temperature of the polymer compound solution (or spinning mold) discharged from the discharge port and the temperature of the non-solvent is calculated. The temperature is preferably within about 100 ° C, within 80 ° C, and within 60 ° C. Thereby, 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 polymer compound solution and a sudden increase in the viscosity of the polymer compound solution. In addition, by keeping the temperature of the non-solvent constant, the phase separation behavior of the polymer compound solution can be stably maintained, and performance such as water permeability and strength can be stably expressed.

  In general, it is preferable that the film is taken out in the linear direction during film formation, and the direction in which the film is taken may be changed after discharging the polymer compound solution. The change in the take-up direction is preferably gradual. This facilitates taking-up while maintaining a constant speed and a uniform load, and makes it possible to minimize deformation of the film structure.

  The hollow fiber membrane obtained by the production method of the present invention can achieve a permeated water amount of pure water larger than 400 LHM, about 600 LMH or more, about 800 LMH or more, or about 1000 LMH or more.

In addition, the internal pressure strength of the film can be about 0.5 MPa or more, about 0.7 MPa or more, or about 0.8 MPa or more.
Furthermore, the external pressure strength of the film can be about 0.2 MPa or more, about 0.3 MPa or more, or about 0.5 MPa or more.
The pressure strength can be evaluated by connecting various pipe joints to both ends of the membrane via metal tubes, using them to actually apply internal and external pressures, and measuring the pressure values when they break. it can.

  Since the hollow fiber membrane of the present invention can have a larger inner diameter than a conventional hollow fiber-shaped water treatment membrane while maintaining sufficient strength, it contains relatively large flocs such as biologically treated waste water. Even when the wastewater is subjected to internal pressure filtration, the membrane is not clogged at the end face of the membrane, that is, at the inlet where the wastewater is introduced.

  Moreover, by forming the hollow fiber membrane of the present invention by the method described above, the balance between the amount of permeated water and the physical strength is particularly excellent as described above. Therefore, it can be suitably used for an existing membrane module and a water treatment apparatus using the same as a separation membrane, and suitable water treatment for the purpose of water purification, in particular, high-concentration waste water treatment becomes possible. . The hollow fiber membrane of the present invention having such characteristics can be suitably used as an ultrafiltration (UF) membrane and a microfiltration (MF) membrane.

  Hereinafter, the hollow fiber membrane of this invention and its manufacturing method are demonstrated in detail based on an Example. The compounding amounts in the examples are shown on a weight basis unless otherwise specified.

Example 1
19% chlorinated vinyl chloride (manufactured by Sekisui Chemical Co., Ltd., HA05K), 1% glass fiber (fiber diameter: 13 μm, fiber length: 75 μm, untreated), 25% polyethylene glycol 200 as a pore-forming agent, N′N-dimethyl A solution of 55% acetamide was prepared. This solution was adjusted to 45 ° C., supplied to a double-pipe structure mold at 200 g / min, and pure water as an internal coagulating liquid was supplied at 200 g / min. Discharge these solutions and the internal coagulation liquid in the air in advance, then immerse the mold in the coagulation water tank with the mold facing downward, and then change the mold sideways to the polymer compound solution in the coagulation water tank. Were subjected to non-solvent induced phase separation to obtain a hollow fiber membrane.
The obtained hollow fiber membrane had an inner diameter of 3.92 mm, a wall thickness of 0.77 mm, and an outer diameter of 5.39 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 1.0 MPa and an external pressure of 0.7 MPa.
The water permeability of pure water was 700 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Pressure resistance performance is achieved by inserting a 4.6 mm diameter metal tube at both ends of the membrane, connecting the place where the tube is inserted with caulking joints, and using a well-known test pump for pressure resistance testing of piping. This is a value obtained by measuring the pressure value when the internal pressure / external pressure is applied and destroyed.
The fractional molecular weight is a value determined by the blocking rate of γ-globulin.

Example 2
A solution of 20% cellulose triacetate, 1% glass fiber (fiber diameter: 11 μm, fiber length: 75 μm, untreated), 14% triethylene glycol as a pore-forming agent, and 2-methyl-Npyrrolidone was prepared. This solution was adjusted to 55 ° C., and in the same manner as in Example 1, the polymer compound solution was subjected to non-solvent induced phase separation in a coagulating water tank to obtain a hollow fiber membrane.
The obtained hollow fiber membrane had an inner diameter of 3.84 mm, a wall thickness of 0.79 mm, and an outer diameter of 5.42 mm, and had a uniform shape without bending, bending, waviness, warping or uneven thickness.
The pressure resistance performance was an internal pressure of 0.5 MPa and an external pressure of 0.3 MPa.
The water permeability of pure water was 580 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Example 3
Polyethersulfone 20%, glass fiber (fiber diameter: 11 μm, fiber length: 75 μm, untreated) 0.5%, polyvinylpyrrolidone (K90) 10% as a pore-forming agent, 2-methyl-Npyrrolidone solution prepared did. This solution was adjusted to 55 ° C., and the polymer compound solution was subjected to non-solvent induced phase separation in a coagulating water tank in the same manner as in Example 1 to obtain a hollow fiber membrane.
The obtained hollow fiber membrane had an inner diameter of 3.92 mm, a wall thickness of 0.77 mm, and an outer diameter of 5.39 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 0.7 MPa and an external pressure of 0.5 MPa.
The water permeability of pure water was 520 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Example 4
A solution of 20% vinyl chloride, 2% glass fiber (fiber diameter: 50 μm, fiber length: 6 μm, silane treatment), 20% polyethylene glycol 200 as a pore-forming agent, and an N′N-dimethylacetamide solution was prepared. This solution was adjusted to 45 ° C., and the polymer compound solution was subjected to non-solvent induced phase separation in a coagulating water tank in the same manner as in Example 1 to obtain a hollow fiber membrane.
The obtained hollow fiber membrane had an inner diameter of 3.8 mm, a wall thickness of 0.8 mm, and an outer diameter of 5.35 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 0.3 MPa and an external pressure of 0.1 MPa.
The water permeability of pure water was 500 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Comparative Example 1
Example 1 except that a solution of 19% chlorinated vinyl chloride (manufactured by Sekisui Chemical Co., Ltd., HA05K), 25% polyethylene glycol 200 as a pore-forming agent and 65% N′N-dimethylacetamide was prepared at 45 ° C. A hollow fiber membrane was formed.
The obtained hollow fiber membrane had an inner diameter of 4.75 mm, a wall thickness of 0.69 mm, and an outer diameter of 6.13 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 1.0 MPa and an external pressure of 0.7 MPa.
The water permeability of pure water was 300 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Comparative Example 2
A hollow fiber membrane was formed in the same manner as in Example 1 except that a solution of 20% cellulose triacetate, 14% triethylene glycol as a pore-forming agent, and 2-methyl-Npyrrolidone was prepared at 55 ° C.
The obtained hollow fiber membrane had an inner diameter of 3.84 mm, a wall thickness of 0.79 mm, and an outer diameter of 5.42 mm, and had a uniform shape without bending, bending, waviness, warping or uneven thickness.
The pressure resistance performance was an internal pressure of 0.5 MPa and an external pressure of 0.3 MPa.
The water permeability of pure water was 400 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Comparative Example 3
A hollow fiber membrane was formed in the same manner as in Example 1 except that a solution of 20% polyethersulfone, 10% polyvinylpyrrolidone (K90) as a pore-forming agent and 70% 2-methyl-Npyrrolidone was prepared at 55 ° C. .
The obtained hollow fiber membrane had an inner diameter of 3.92 mm, a wall thickness of 0.77 mm, and an outer diameter of 5.39 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 0.7 MPa and an external pressure of 0.5 MPa.
The water permeability of pure water was 380 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

Comparative Example 4
A hollow fiber membrane was formed in the same manner as in Example 1 except that 20% of vinyl chloride, 20% of polyethylene glycol 200 as a pore-forming agent, and a solution of N′N-dimethylacetamide were prepared at 45 ° C.
The obtained hollow fiber membrane had an inner diameter of 3.8 mm, a wall thickness of 0.8 mm, and an outer diameter of 5.35 mm, and had a uniform shape without bending, bending, waviness, warpage or uneven thickness.
The pressure resistance performance was an internal pressure of 0.3 MPa and an external pressure of 0.1 MPa.
The water permeability of pure water was 400 L / m ² · hr · atm.
The molecular weight cut-off was 150,000.

  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 as a water treatment membrane, a microfiltration membrane, an ultrafiltration membrane or the like, and can be advantageously used particularly for MBR.

Claims (6)

A hollow fiber membrane obtained by non-solvent induced phase separation of a polymer compound solution containing a polymer compound and a solvent,
Containing 0.1 to 10% by weight of an inorganic compound with respect to the polymer compound;
It has a self-supporting structure with an outer diameter of 3.6 to 10 mm, an SDR value of 5.8 to 34, which is the ratio of outer diameter to wall thickness, and an inner diameter of 3.2 mm or more, and has a separation function on both sides. Hollow fiber membrane.   The hollow fiber membrane according to claim 1, wherein the inorganic compound is a fine particle having an average primary particle diameter of 10 µm or less, or a fibrous compound having a fiber diameter of 5 to 50 µm and a fiber length of 200 µm or less.   The hollow fiber membrane according to claim 1 or 2, which has a fractionation property of an ultrafiltration membrane or a microfiltration membrane. The internal pressure strength of the film is 0.3 MPa or more,
The hollow fiber membrane according to claims 1 to 3, wherein the resistance to external pressure is 0.1 MPa or more and the water permeability of pure water is larger than 400 L / m ² · hr · atm. Preparing a solution of the polymer compound,
An inorganic compound is mixed in the polymer compound solution at 0.1 to 10% by weight with respect to the polymer compound,
The obtained polymer compound solution is discharged into a non-solvent to cause non-solvent induced phase separation,
Hollow fiber membrane having a self-standing structure with an outer diameter of 3.6 to 10 mm, an SDR value of 5.8 to 34, which is a ratio of outer diameter to wall thickness, and an inner diameter of 3.2 mm or more, and having a separation function on both sides A process for producing a hollow fiber membrane, characterized in that   Claims that the polymer compound solution is solidified by immersing the discharge port in a coagulation tank containing the non-solvent from a state in which the polymer compound solution is discharged into the air from a mold having a discharge port. Item 6. A method for producing a hollow fiber membrane according to Item 5.