JPH0376975B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a hollow fibrous separation membrane. More specifically, the present invention relates to a method for producing a polyethersulfone hollow fiber separation membrane having both excellent mechanical strength and superior properties. The purpose is to create a polyether sulfone hollow fiber separation membrane that has excellent mechanical strength and can withstand continuous filtration for long periods of time due to its stable overpass characteristics, by using a spinning dope with a specific composition. Our goal is to provide the following. [Prior Art] Separation membranes made of polyether sulfone are known to have excellent properties mainly in the ultraviolet range. In addition, polyether sulfone originally has excellent heat resistance, chemical resistance, and safety, and therefore its uses are wide-ranging, such as in the food industry, the medical field, and as a support material for reverse osmosis membranes. On the other hand, Japanese Patent Publication No. 50-22508 is known as a method for manufacturing separation membranes that has been commonly used in the past, and if this method is followed, the resistance to liquid flow through the barrier layer on the surface and the membrane following this is known. A polymer membrane consisting of a support layer having a porous structure with small pores and sufficient openings is obtained. A separation membrane with such a structure is characterized by a high overflow rate per unit membrane area, but its drawbacks include low mechanical strength, and because the overflow rate is too high, the concentration at the membrane surface is high. Polarization is significant, and therefore scale adhesion and deposition on the surface increases.
As a result, it was mentioned that the overflow rate decreases rapidly when continuous filtration is performed. [Object of the Invention] The present inventors have solved the above-mentioned drawbacks of conventional separation membranes, and have developed a separation membrane that has a high overflow rate, allows stable filtration for a long time, and has mechanical strength. As a result of intensive research to find a method for producing polyether sulfone, its solvent,
An extremely excellent method is to form a resin stock solution containing an additive in combination with an alcoholic solvent or metal salt and a second component into a film by casting or spinning, and then coagulate it by contact with a non-solvent of the resin. As a result of various studies based on this knowledge, we have completed the present invention. [Structure of the Invention] That is, the present invention uses a hollow fiber manufacturing nozzle with a double tube structure, and injects a spinning dope from the outer annular opening.
In the wet spinning method in which a coagulating liquid is discharged from the core into a coagulating bath and coagulated, the spinning stock solution is polyether sulfone, a polar organic solvent that dissolves the resin, and a combination of main additives and sub-additives as additives. ,
The additive/solvent mixing weight ratio is 1/99 to 1/4
This is a method for producing a hollow fibrous separation membrane, characterized in that: To explain the present invention in more detail, the spinning dope contains 10 to 25% by weight, preferably 12 to 20% by weight of polyethersulfone, a solvent for polyethersulfone, and a combination of main additives and sub-additives. It is obtained by dissolving it in a mixed solvent consisting of additives at room temperature or by heating. What is polyether sulfone?

〔Effect of the invention〕

The structure of the polyether sulfone hollow fiber separation membrane obtained by the method of the present invention is that the inner surface
It has pores of 0.05μ or less and pores of 15μ or less on the outer surface, and the inner surface is highly smooth, so there is little scale adhesion during filtration. Furthermore, when the excess fluid is blood, there is less deposition of blood cell components and the like.
The intermediate layer sandwiched between the inner and outer surface layers can be prepared in a wide range from a void structure to a sponge structure by combining the compositions of the spinning dope and coagulation solution, and a relatively dense internal structure can be obtained. The membrane has excellent mechanical strength. Furthermore, the relatively dense internal structure and the small pores on the outer surface both provide appropriate resistance to excessive fluid, suppressing concentration polarization at the membrane surface that normally occurs with high-flow rate membranes, resulting in stable membranes. Continuous passing is possible. The reason why the above-mentioned excellent characteristics are developed in the present invention is not clear, but it is due to the process in which the spinning dope comes into contact with the coagulation solution, the exchange of water and solvent progresses, the polyether sulfone coagulates, and the fine structure of the membrane is formed. It is presumed that the presence of the main additive and sub-additive in the spinning dope acts on the exchange of water and solvent and appropriately controls the rate, resulting in the formation of a distinctive membrane structure. Examples of the present invention will be described below. Examples 1 and 2 Polyether sulfone (manufactured by ICI,
Victrex300P) as raw material and other compositions as the first
As shown in the table, these were mixed and heated and stirred at 80°C for 4 hours to obtain a homogeneous solution. Water was discharged from the outer annular opening of the hollow fiber manufacturing nozzle and from the core, and the spinning dope was introduced into a water coagulation bath where it was coagulated and wound at a speed of 45 m/min. Here, the spinning temperature, that is, the temperature of the spinning dope and the internal coagulation liquid, was 40°C. The rolled ivy hollow fiber separation membrane was immersed in ethanol for 6 hours and then heated to 60°C.
It was immersed in warm water for 12 hours, and then washed by immersion in running water for 3 hours. The obtained film has an inner diameter of 250μ and a film thickness.
It was 50μ. Next, 1000 membranes with an effective length of 20 cm were bundled, both ends fixed with adhesive, and then cut to obtain a membrane module having openings at both ends. To evaluate the performance of the membrane module, a 1% aqueous solution 2 of dextran (manufactured by Pharmacia Fine Chemicals, T70) with a weight average molecular weight of approximately 70,000 was circulated with a pump at a flow rate of 200 ml/min, and the filtrate was returned to the circulating fluid. At this time, changes in overspeed and dextran inhibition rate over time were measured. Here, the terms are explained as follows. Overrate (ml/mmHg・time・m ² )=amount of liquid passed (
ml)/overpressure (mmHg) x elapsed time (hours) x effective membrane area (m ² ) Rejection rate (%) = (1- Solute concentration in the liquid (
%)/Solute concentration of circulating fluid (%)) x 100 The measurement results at 5 minutes, 30 minutes, 1 hour, 2 hours, and 3 hours after the start of circulation are as shown in Table 2.
Both overspeed and dextran rejection were stable.

【table】

【table】

[Table] In the Examples and Comparative Examples described below, unless otherwise specified, film formation and evaluation were carried out in the same manner as in Examples 1 and 2. Comparative Examples 1, 2, 3 The composition and measurement results of the spinning dope were
Table 4 shows the results. Both cases showed high initial overspeeds, but the subsequent decline was significant and decreased almost linearly. The inhibition rate of dextran showed a tendency to increase as time progressed. This is considered to be due to clogging of dextran molecules on the membrane surface.

【table】

[Table] Examples 3 and 4 The composition of the spinning dope was as shown in Table 5.
However, the film was formed at a spinning temperature of 50° C. and a winding speed of 37 m/min, and the inner diameter and thickness of the obtained film were 230 μm and 45 μm, respectively. The overspeed and dextran rejection rate are shown in Table 6, and both showed stable performance.

【table】

[Table] Examples 5 and 6 The composition of the spinning dope was as shown in Table 7, and the rest was the same as in Examples 3 and 4. The overspeed and dextran rejection rate are shown in Table 8, and both showed stable performance.

【table】

【table】

【table】

[Table] Examples 7, 8, 9, 10 The composition of the spinning dope was as shown in Table 9.
However, the spinning temperature was 45℃, the winding speed was 42m/min, and the inner diameter and thickness of the obtained membrane were 200μ and 200μ, respectively.
It was 30μ. Performance evaluation was performed by circulating a physiological saline solution 2 containing 0.2% human albumin with a pump at a flow rate of 200 ml/min.
At that time, changes in overspeed and human albumin inhibition rate were measured. The results are shown in Table 10, and showed extremely stable overperformance even in solutions containing human albumin. Surfactants A and B used in Examples 7 and 8 are both commercially available from Kao Atlas Co., Ltd., and are sodium dodecylbenzenesulfonate (trade name: Neopellex 05) and polyoxyethylene sorbitan, respectively. It is monostearate (trade name: Tween 60).

【table】

【table】

Claims (1)

[Claims] 1. Using a hollow fiber manufacturing nozzle with a double tube structure,
In the wet spinning method, in which the spinning stock solution is discharged from the outer annular port and the coagulation solution is discharged from the core into a coagulation bath and coagulated, the spinning stock solution contains polyether sulfone, a polar organic solvent that dissolves the resin, and a main additive as an additive. and a sub-additive, the additive/solvent mixture weight ratio is 1/99 to 1/4, and the main additive is a monohydric and dihydric alcohol solvent having 2 to 4 carbon atoms. or at least one selected from monovalent and divalent cationic metal salts, and the sub-additive is a ketone-based, ether-based, furan-based, organic acid-based, organic acid anhydride-based, or organic acid ester-based additive. A method for producing a hollow fibrous separation membrane, comprising at least one selected from a solvent and a surfactant. 2. Claim 1, wherein the composition of the coagulating liquid and coagulating bath is water, or water and a metal salt, and/or a solvent for the resin, and/or a non-solvent for the resin.
A method for producing a hollow fibrous separation membrane as described in . 3. The method for producing a hollow fibrous separation membrane according to claim 1, wherein the polyether sulfone is made of a polymer having repeating units of the formula: 4. The method for producing a hollow fibrous separation membrane according to claim 1, wherein the mixing weight ratio of main additive/auxiliary additive used in the spinning dope is 1/9 to 9/1.