JPH0445210B2 - - 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, including 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, a resin stock solution containing polyether sulfone, its solvent, and a surfactant was formed into a film by casting or spinning, and then brought into contact with a non-solvent of the resin. We discovered that the solidification method is an extremely excellent method, and based on this knowledge, we conducted various studies and as a result, we 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 a wet spinning method in which a coagulating liquid is discharged from a core into a coagulating bath and coagulated, the spinning stock solution contains polyether sulfone, a polar organic solvent that dissolves the resin, and a surfactant (excluding polyoxyethylene alkyl ether), This is a method for producing a hollow fibrous separation membrane, characterized in that the mixing weight ratio of surfactant/solvent is 1/99 to 1/3. To explain the present invention in more detail, the spinning dope is prepared by adding 10 to 25% by weight, preferably 12 to 20% by weight, of polyethersulfone to a mixed solvent consisting of a polyethersulfone solvent and a surfactant at room temperature or under heating. Obtained by dissolving. 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 surfactant in the spinning dope acts on the exchange of water and solvent and moderately controls the exchange rate, resulting in the formation of a distinctive membrane structure. Examples of the present invention will be described below. Example 1 Polyether sulfone (manufactured by ICI,
Mix 14% by weight of Victrex 300P), 76% by weight of dimethylformamide as a solvent, and 10% by weight of sodium lauryl sulfate (manufactured by Kao Atlas Co., Ltd., Emar 10) as a surfactant, and heat and stir at 90°C for 4 hours. A homogeneous solution was obtained. This spinning dope was discharged from the outer annular opening of the hollow fiber manufacturing nozzle and water was discharged from the core, led to a coagulation bath consisting of water, and coagulated, and wound up at a speed of 35 m/min. Here, the spinning temperature, that is, the temperature of the spinning dope and the internal coagulation liquid, was 40°C. The wound hollow fibrous separation membrane was immersed in warm water at 60°C for 12 hours, and then in running water for 3 hours. The obtained membrane has an inner diameter
It was 230μ, and the film thickness was 45μ. 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. To explain the terms here, overspeed (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 liquid (%) / solute concentration in circulating fluid (
%))×100 As a result of the measurement, the overspeed 5 minutes after the start of circulation was 590.
(ml/mmHg・hour・m ² ), and the values for the next 30 minutes, 1 hour, 2 hours, and 3 hours are 560, 535, respectively.
A high overspeed of 510 and 510 (ml/mmHg・hour・m ² ) was maintained, and the decrease was extremely small. In addition, the inhibition rate of dextran was 34 (%) at 5 minutes, and at 30 minutes, 1 hour, 2 hours, and 3 hours, respectively.
It was stable at 36, 37, 38, 38 (%). Comparative Example 1 A film was formed by dissolving 14% by weight of polyether sulfone (300P) and 86% by weight of dimethylformamide in the same manner as in Example 1, and performance evaluation was performed.
The 5-minute overspeed is 880 (ml/mmHg・hour・m ² )
However, after that, the value decreased significantly, and the value decreased significantly after 30 minutes, 1 hour, 2 hours, and 3 hours.
It decreased almost linearly to 800, 730, 615, and 520 (ml/mmHg・hour・m ² ). On the other hand, the inhibition rate of dextran showed a tendency to increase at 21, 28, 35, 45.5, and 52.5 (%) up to 5 minutes, 30 minutes, 1 hour, 2 hours, and 3 hours, respectively. Example 2 14% by weight of polyether sulfone (300P),
A mixture of 74% by weight of dimethylhelmamide as a solvent and 12% by weight of lauryl betaine (manufactured by Kao Atlas Co., Ltd., Amhitol 24B) as a surfactant was heated and stirred at 90°C for 4 hours to obtain a homogeneous solution. . Using this as a spinning stock solution, membrane formation and treatment were performed in the same manner as in Example 1 at a spinning temperature of 40°C to create a membrane module, and the overspeed and rejection rate of the dextran aqueous solution were measured. As shown in Table 1, changes in overspeed and rejection were both stable. Example 3 16% by weight of polyether sulfone (300P),
70% by weight of N-methyl-2-pyrrolidone as a solvent and 14% by weight of polyoxyethylene sorbitan monostearate (manufactured by Kao Atlas Co., Ltd., Tween 60) as a surfactant were mixed, and the mixture was heated at 90℃ for 4 hours.
The homogeneous solution obtained by heating and stirring for several hours was used as a spinning stock solution. Next, the performance of the membrane module obtained in the same manner as in Example 2 was evaluated.
The results are shown in Table 1.

[Table] Example 4 16% by weight of polyether sulfone (300P), 76% by weight of dimethylformamide as a solvent, and 8% by weight of lauryltrimethylammonium chloride (manufactured by Kao Atlas Co., Ltd., Cortamine 24P) as a surfactant were mixed. The mixture was heated and stirred at 90°C for 4 hours to obtain a homogeneous solution. Furthermore, film formation was performed in the same manner as in Example 3. However, the winding speed was 40 m/min and the spinning temperature was 50°C. The inner diameter of the obtained membrane is
The 200μ film thickness was 35μ. The membrane module has an effective length
The length was 16 cm, and the number of membranes was 2000. Physiological saline solution 2 containing 0.2% human albumin was circulated through this with a pump at a flow rate of 200 ml/min, and changes in overspeed and rejection rate were measured. As a result, 5 minutes, 30 minutes, 1 hour, 2
The overspeed is 540 for hours, 3 hours, and 4 hours, respectively.
530, 525, 520, 515 (ml/mmHg・hour・m ² ), and the inhibition rate of human albumin is 89, 92, 93.5, 94.5,
It was stable at 95. Examples 5 to 8 15% by weight of polyether sulfone (300P), sodium dodecylbenzenesulfonate as a surfactant (manufactured by Kao Atlas Co., Ltd., Neoperex
05) at 3, 8, 14, 20% by weight, and the solvent N-methyl-2-pyrrolidone in proportion to the amount of surfactant.
82, 77, 71, and 65% by weight, respectively, to give Examples 5 to 8 in that order. These were stirred and dissolved at 90°C for 4 hours to obtain a spinning stock solution. Next, a film was formed in the same manner as in Example 4 to create a module. Performance evaluation of the module was also carried out using human albumin in the same manner as in Example 4, and the results are shown in Table 2.

【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 surfactant (polyoxy (excluding ethylene alkyl ether), and the mixing weight ratio of the surfactant/the solvent is 1/99 to 1/99.
3. A method for producing a hollow fibrous separation membrane, characterized in that: 2. Claim 1, wherein the composition of the coagulating liquid and the 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 Polyether sulfone A method for producing a hollow fibrous separation membrane according to claim 1, comprising a polymer having repeating units.