JP2011020071A - Method for manufacturing polysulfone-based hollow fiber membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polysulfone-based hollow fiber membrane with high water permeability and membrane strength in which the high level of the yield can be maintained at the time of producing a blood purification device. <P>SOLUTION: In the method for manufacturing a hollow fiber membrane including a process in which a raw liquid for spinning polymer is prepared by charging a polysulfone-based polymer, a hydrophilic polymer, an aprotic solvent and a non-solvent into a tank, and by uniformly dissolving by heating up after mixing and is filtered through a filter installed in a liquid feed line, discharged through a nozzle, and then immersed in a coagulating bath, the temperature of the raw liquid for spinning polymer moving from the tank to the filter is in a range of 70-95°C, and the temperature at the discharge through the nozzle is lower than the above temperature and in a range of 40-70°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a polysulfone-based hollow fiber membrane having high water permeability and membrane strength.

  Polysulfone-based hollow fiber membranes are relatively easy to produce and can be controlled over a wide range of pore diameters, and have been put to practical use as various types of separation membranes such as industrial filtration membranes and medical hemodialysis membranes.

  In spinning of a polysulfone-based hollow fiber membrane, an aprotic organic solvent such as dimethylacetamide or N-methylpyrrolidone is often used as a solvent for the polymer. In order to control the pore size and porosity of the membrane, a non-solvent that is compatible with the solvent but not dissolved in the polymer is often added to the spinning polymer stock solution. As this non-solvent, polyhydric alcohols such as ethylene glycol, triethylene glycol, and glycerin, and water are used. Of these, water is often used because it has a strong non-solvent property with respect to the polymer, and thus it can usually control the phase separation in a few percent with respect to the spinning polymer stock solution.

  Patent Document 1 discloses a low-temperature dissolving stock solution and a production method thereof. Specifically, 15 wt% of a polysulfone polymer, 8 wt% of polyvinylpyrrolidone, 70 to 82 wt% of a solvent and 0 to 8 wt% of a non-solvent are heated and dissolved at 80 to 110 ° C, and the phase separation temperature of the heated and dissolved stock solution is 25. It is described that it is -100 degreeC. It is described that such a stock solution is easy to be stored at a low temperature and can be advantageously used for the production of a semipermeable membrane having a particularly large pore size.

  In Patent Document 2, polysulfone-based polymer 16 wt%, polyethylene glycol 17.6 wt%, polyvinyl pyrrolidone 2.4 wt%, and dimethylformamide 64 wt% are heated and dissolved at 120 ° C., and phase separation is performed at 140 ° C. or higher and 9 ° C. or lower. It describes that a membrane solution was prepared and that this membrane-forming solution was kept at 40 ° C. or 35 ° C. and discharged from a double annular nozzle. Patent Document 3 discloses that polysulfone resin 19 wt%, polyvinyl pyrrolidone 1.9 wt%, polyethylene glycol 30.4 wt%, and dimethylformamide 48.7 wt% are dissolved at 120 ° C. and phase separated at 75 ° C. or higher and 29 ° C. or lower. It has been described that a spinning stock solution that causes stagnation was obtained and the spinning stock solution was kept at 45 ° C. and discharged from a double annular nozzle.

  Since these polysulfone-based hollow fiber membranes have an asymmetric structure, the membrane strength is low. Therefore, it is necessary to increase the film thickness as compared with a membrane having a uniform structure. On the other hand, if the polymer concentration in the spinning polymer stock solution is increased in order to increase the membrane strength, there is a problem that the water permeability performance is lowered.

  In order to solve such a problem, Patent Document 4 discloses a hollow fiber membrane having no defect by setting the pore diameter of a filter for removing impurities from a spinning polymer stock solution within a certain range and reducing the variation in the slit width of the discharge nozzle. It is disclosed that it can be obtained. However, this method suppresses a decrease in film strength caused by defects, does not improve the strength of the film itself, and cannot be expected to improve the film performance.

JP-A-63-97666 Japanese Patent Laid-Open No. 11-169693 JP 03-258330 A Japanese Patent Laid-Open No. 2005-21510

  The present invention was invented in view of the current state of the prior art, and the object thereof is a polysulfone-based hollow having high water permeability and membrane strength and capable of maintaining the yield at the time of creating a blood purifier at a high level. It is providing the manufacturing method of a thread film.

  As a result of intensive studies to achieve the above object, the present inventor has found that control of the holding temperature and the discharge temperature of the spinning polymer stock solution is important for the membrane strength and water permeability of the hollow fiber membrane. Generally, a spinning polymer stock solution of a polysulfone-based hollow fiber membrane using an aprotic organic solvent and a non-solvent has high temperature stability when dissolved, and does not cause coagulation or phase separation even when the temperature is lowered to about room temperature. For this reason, after the polymer is completely dissolved at a high temperature, the temperature of the spinning polymer stock solution is kept at about 40 ° C. in order to reduce the energy cost. Thereafter, when the spinning polymer stock solution is discharged from the nozzle, the discharge temperature affects the pore diameter of the membrane, so the discharge nozzle temperature is set in accordance with the target hollow fiber membrane pore diameter.

  As a result of detailed examination of the influence of the holding temperature and discharge temperature of the dissolved spinning polymer stock solution on the strength and membrane performance of the hollow fiber membrane, the inventor has controlled the holding temperature and discharge temperature of the spinning polymer stock solution within a specific temperature range. It was found that the membrane strength and water permeability of the hollow fiber membrane can be improved.

That is, the present invention has the following configurations (1) to (3).
(1) A polysulfone-based polymer, a hydrophilic polymer, an aprotic organic solvent, and a non-solvent were placed in a tank and mixed, and then a spinning polymer stock solution that was heated and uniformly dissolved was provided in the liquid-feeding line. In a hollow fiber membrane manufacturing method including a step of filtering through a filter, then discharging from a nozzle, and then immersing in a coagulation bath, the temperature of the spinning polymer stock solution from the tank to the filter is in the range of 70 to 95 ° C, and the nozzle is discharged A method for producing a polysulfone-based hollow fiber membrane, wherein the temperature is lower than the above temperature and is in the range of 40 to 70 ° C.
(2) The polysulfone-based hollow fiber according to (1), wherein the mass ratio of the hydrophilic polymer in the spinning polymer stock solution is 1 to 20 mass% with respect to the total amount of the polysulfone-based polymer and the hydrophilic polymer. A method for producing a membrane.
(3) The method for producing a polysulfone-based hollow fiber membrane according to (1) or (2), wherein the hydrophilic polymer is polyvinylpyrrolidone.

  The production method of the polysulfone-based hollow fiber membrane of the present invention is maintained at a temperature higher than usual until the dissolved spinning polymer stock solution is discharged, and is lower than the temperature at the time of discharge, so that the membrane strength and water permeability of the hollow fiber membrane are reduced. In addition, the yield when creating a blood purifier is high.

Hereinafter, the present invention will be described in detail.
The present invention maintains a spinning polymer stock solution of a polysulfone-based hollow fiber membrane using an aprotic organic solvent and a non-solvent at a temperature in the range of 70 to 95 ° C., excluding the discharge nozzle portion. It has been found that the strength and water permeability of the hollow fiber membrane are improved by setting the temperature lower. Although the cause of this phenomenon has not been clearly analyzed, when the polymer is stabilized and the entanglement of the polymer chains proceeds, the strength of the resulting film increases and is discharged from the nozzle. It is presumed that the coagulation becomes uniform and the thickness unevenness of the skin layer decreases.

  When the strength of the hollow fiber membrane is reduced, the hollow fiber itself is broken or broken during the production of the blood purification dialyzer, and the productivity is significantly reduced. In addition, there is a problem that the risk of blood leakage to the dialysate increases during clinical use. In order to clear this problem, the hollow fiber membrane obtained by the production method of the present invention has a breaking strength per hollow fiber of 14 g or more, and further 15 g or more.

The hollow fiber membrane obtained by the production method of the present invention has a water permeability (UFR) of 200 to 450 ml / (m ² · hr · mmHg). When the UFR is less than 200 ml / (m ² · hr · mmHg), the ability to remove low molecular weight proteins required as a dialysis membrane may not be obtained, and the UFR is greater than 450 ml / (m ² · hr · mmHg). In some cases, protein leakage may not be suppressed. When the amount of protein leakage increases during clinical use, the blood protein concentration in the living body is lowered, which may cause hypoproteinosis. The lower limit of UFR is more preferably 250 ml / (m ² · hr · mmHg) or more, and further preferably 300 ml / (m ² · hr · mmHg) or more. The upper limit of UFR is more preferably 420 ml / (m ² · hr · mmHg) or less, and further preferably 400 ml / (m ² · hr · mmHg) or less.

  The spinning polymer stock solution of the hollow fiber membrane is maintained at a temperature of 70 to 95 ° C. except for the discharge nozzle portion. If the maintenance temperature is less than 70 ° C, the spinning polymer stock solution may become unstable, resulting in a decrease in yarn strength or water permeability. If the maintenance temperature is higher than 95 ° C, thermal degradation of the spinning polymer stock solution will proceed. It is not preferable. The lower limit temperature is more preferably 72 ° C. or higher, and particularly preferably 75 ° C. or higher. The upper limit temperature is more preferably 90 ° C. or less, and particularly preferably 85 ° C. or less.

  In the production method of the present invention, the temperature of the nozzle discharge portion of the spinning polymer stock solution is set to be lower than the range of the maintenance temperature. This is because the discharge temperature greatly affects the structure and performance of the completed hollow fiber membrane. Specifically, the discharge temperature of the spinning polymer stock solution is set in the range of 40 to 70 ° C. When the temperature is lower than 40 ° C., the water permeability may be lowered. When the temperature is higher than 70 ° C., the amount of protein leakage may increase when the hollow fiber membrane is clinically used. The lower limit temperature is preferably 45 ° C. or higher, more preferably 48 ° C. or higher, and particularly preferably 50 ° C. or higher. The upper limit temperature is preferably 65 ° C. or less, preferably 62 ° C. or less, and more preferably 60 ° C. or less.

  However, when the nozzle discharge temperature of the spinning polymer stock solution is made lower than the above maintenance temperature, if the time of the state is long, the spinning polymer stock solution becomes unstable, and therefore it is preferably within 1 hour, more preferably within 30 minutes. In order to do this, the heat transfer medium of the part where the spinning polymer stock solution is dissolved and transferred and the nozzle discharge part are divided, and only the discharge part is set to a lower temperature than the other part, and the temperature is set to a lower temperature. It is necessary to calculate the retention volume of the spinning polymer stock solution at the discharge portion from the discharge speed and to shorten the retention time as described above.

  In the production method of the present invention, the temperature before the nozzle discharge portion of the spinning polymer stock solution is set to 70 to 95 ° C., but when the raw material polysulfone polymer, solvent, and non-solvent are charged into the dissolution tank, It is difficult to do. Therefore, in the present invention, the applicable range of this temperature is from the tank in which the polymer is dissolved to the filtration filter before discharge of the nozzle.

  The spinning polymer stock solution used in the production method of the present invention is obtained by mixing a polysulfone-based polymer, a hydrophilic polymer, an aprotic organic solvent, and a non-solvent into a tank and mixing them, followed by heating to obtain a uniform solution. It is what

The polysulfone-based polymer is a generic name for polymers having a sulfone bond, and is not particularly limited, and examples thereof include polysulfone and polyethersulfone having repeating units shown below. These are widely used and are preferably used because they are easily available.

  As the hydrophilic polymer, those that form a micro phase separation structure with a polysulfone polymer are preferably used. For example, polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone and the like can be mentioned, and polyvinyl pyrrolidone is preferable from the viewpoint of safety and economy. Polyvinyl pyrrolidone is a water-soluble polymer compound obtained by vinyl polymerization of N-vinyl pyrrolidone. The product names are “Collidon” from BASF, “Prasdon” from ISP, and “Pittscall” from Daiichi Kogyo Seiyaku. There are products of various molecular weights that are commercially available. In general, a low molecular weight is preferred for imparting hydrophilicity, while a high molecular weight is suitable for reducing the amount of elution, but it is appropriately selected according to the required characteristics of the hollow fiber membrane bundle of the final product. . Those having a single molecular weight may be used, or two or more products having different molecular weights may be mixed and used. Moreover, you may use what refine | purified a commercial product and sharpened molecular weight distribution, for example.

  Examples of the aprotic organic solvent include dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, dimethylformamide and the like, and these can be used alone or in a mixed state. Among these, dimethylacetamide and N-methylpyrrolidone can be preferably used because the polysulfone-based polymer has high solubility, a relatively high boiling point, and high safety.

  The non-solvent is compatible with the solvent, but the polysulfone polymer does not dissolve, and has a role of promoting and controlling phase separation of the spinning polymer stock solution. Examples of the non-solvent include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, and glycerin, and water.

  The spinning polymer stock solution is obtained by mixing the above raw materials in a tank and then heating to uniformly dissolve the spinning polymer stock solution. The spinning polymer stock solution is sent from the tank to a nozzle through a liquid feeding line. At this time, insoluble components and gel in the spinning polymer stock solution are filtered and removed by a filter provided in the liquid feeding line. The spinning polymer stock solution thus obtained is discharged from a nozzle, immersed in a coagulation bath to form a hollow fiber membrane, and the hollow fiber membrane is washed with water and dried to become a final product.

  As the method for producing the polysulfone-based hollow fiber membrane of the present invention, conventionally known methods can be basically employed except for the spinning polymer stock solution holding temperature and the nozzle discharge temperature, for example, as described in JP-A No. 2000-300663 Can be employed. Specifically, first, 16% by mass of polyethersulfone (4800P, manufactured by Sumitomo Chemical Co., Ltd.), 5% by mass of polyvinylpyrrolidone (K-90, manufactured by BASF), 74% by mass of dimethylacetamide, and 5% by mass of water are contained in the tank. Then, the mixture is heated and uniformly dissolved to obtain a spinning polymer stock solution. After defoaming and filtering with a filter, 50% dimethylacetamide aqueous solution is discharged as a core solution simultaneously from the outside and inside of the double-tube orifice nozzle, solidified by 75 ° C water through a 50 cm free running part. A method of introducing into a bath, forming a hollow fiber membrane, winding up after washing with water, and drying at 60 ° C. can be mentioned.

  In the present invention, the mass ratio of the hydrophilic polymer in the spinning polymer stock solution is preferably 1 to 20 mass% with respect to the total amount of the polysulfone polymer and the hydrophilic polymer. If the proportion of polyvinylpyrrolidone is too small relative to the polysulfone-based polymer, the effect of imparting hydrophilicity to the membrane may be insufficient. Therefore, the lower limit of the mass ratio is preferably 1.5% by mass or more, more preferably 2.0% by mass or more, and further preferably 2.5% by mass or more. On the other hand, if the ratio is too large, the effect of imparting hydrophilicity is saturated, and the amount of polyvinylpyrrolidone and / or oxidatively deteriorated material eluted from the membrane increases, and the amount of polyvinylpyrrolidone eluted from the membrane may exceed 10 ppm. is there. Therefore, the upper limit of the mass ratio is preferably 18% by mass or less, more preferably 15% by mass or less, further preferably 13% by mass or less, and particularly preferably 10% by mass or less.

  The membrane structure of the hollow fiber membrane has a sponge structure close to a uniform structure, and in recent years, a dense layer that performs substantially selective separation for the purpose of improving dialysis efficiency and a support layer that maintains membrane strength with a high porosity. There are some combinations. However, in any hollow fiber membrane, the factor that determines the permeation of the waste is mainly the sponge structure or the membrane structure of the dense layer, and usually exists in the portion in contact with the liquid to be treated. The state of the polymer that forms the membrane in the dry state can be controlled by the polymer concentration in the spinning dope, the solvent that promotes phase separation that forms the pore structure, the ratio of non-solvent, the temperature of the spinneret, etc. Some have a membrane structure such as a body and a network structure in which polymers are intertwined linearly. In the present invention, the polymer concentration in the spinning dope is preferably set slightly higher than the spinnability limit so that the membrane forms a membrane structure like an aggregate of polymer particles. For example, in the case of polyethersulfone, the polymer concentration in the spinning dope is preferably 16% by mass or more.

  The inner diameter of the polysulfone-based hollow fiber membrane of the present invention is preferably 100 to 300 μm. When the inner diameter is less than 100 μm, the pressure loss of the hollow fiber membrane increases, so that hemolysis may occur when blood is flowed. Therefore, the lower limit of the inner diameter is more preferably 130 μm or more, and further preferably 150 μm or more. On the contrary, when the inner diameter is larger than 300 μm, the shear rate of blood flowing in the hollow fiber membrane is low, and there is a tendency that proteins and the like are easily deposited on the inner surface of the membrane with filtration. Therefore, the upper limit of the inner diameter is more preferably 280 μm or less, and further preferably 260 μm or less.

  The film thickness of the polysulfone-based hollow fiber membrane of the present invention is preferably 20 to 100 μm. When the film thickness is less than 20 μm, the spinnability of the hollow fiber membrane and the assemblability of the blood purifier are very poor. Therefore, the lower limit of the film thickness is more preferably 21 μm or more, and further preferably 22 μm or more. On the contrary, when the film thickness is larger than 100 μm, the permeation performance tends to deteriorate, and proteins and the like tend to be easily adsorbed to the film. Therefore, the upper limit of the film thickness is more preferably 50 μm or less, and further preferably 35 μm or less.

  Hereinafter, although the effect of the present invention is shown by an example, the present invention is not limited to these at all.

(Mass ratio of hydrophilic polymer in membrane)
The measurement method when polyvinylpyrrolidone (PVP) is used as the hydrophilic polymer is shown. The hollow fiber membrane was dried at 80 ° C. for 48 hours using a vacuum dryer, 10 mg of which was analyzed with a CHN coder (manufactured by Yanaco Analytical Industrial Co., Ltd., MT-6 type), and the mass ratio of PVP from the nitrogen content was as follows: Calculated by the formula.
Mass ratio (mass%) of hydrophilic polymer = nitrogen content (mass%) × 111/14

(Hollow fiber membrane thickness)
The cross-section of the hollow fiber membrane is projected with a projector having a magnification of 200 times, and the inner diameter (A) and outer diameter (B) of the hollow fiber of maximum, minimum, and medium sizes are measured in each field of view. The average film thickness of 90 hollow fibers of 30 fields of view was calculated.
Film thickness (μm) = (B−A) / 2

(Breaking strength)
A tensile test was performed on a hollow fiber test piece having an effective sample length of 10 cm using Tensilon (UTM11 manufactured by Toyo Baldwin) at a crosshead speed of 10 cm, and the breaking point was measured. Thirty samples were measured and the average value was taken as the result. The measurement was performed in a temperature and humidity environment of 20 ± 5 ° C. and 60 ± 10% RH. When the hollow fiber was in a wet state, the hollow fiber was allowed to stand for 24 hours in a measurement environment, and the hollow fiber was substantially dried.

(Ultrafiltration coefficient of pure water (UFR))
Using a blood purifier, the inner and outer surfaces of the membrane were filled with pure water, and the temperature was kept constant at 37 ° C. A 37-degree pure water is flowed by applying pressure from the blood purifier inlet leading to the inside of the membrane, causing a pressure difference between the inside and outside of the membrane, that is, a pressure difference between the membranes, and exiting outside the membrane through the membrane in 1 minute. The amount of pure water coming was measured. The transmembrane pressure difference (TMP) is set to TMP = (Pi + Po) / 2 (Pi is the blood purifier inlet pressure, Po is the blood purifier outlet pressure). At four different transmembrane pressure differences, the water permeation amount for 1 minute was measured, plotted on the two-dimensional coordinates of the transmembrane pressure difference and the water permeation amount, and the slopes of these approximate lines were obtained. This value was multiplied by 60 and divided by the membrane area of the blood purifier to obtain the ultrafiltration coefficient (UFR) of pure water of the hollow fiber membrane. The unit of UFR is ml / (m ² · hr · mmHg).

(Leak test)
A 37 ° C. bovine blood to which citric acid was added and coagulation was suppressed was fed to a blood purifier filled with 10,000 hollow fibers at 200 mL / min, and the blood was filtered at a rate of 10 mL / min. At this time, the filtrate is returned to blood to be a circulatory system. After 60 minutes, the filtrate of the blood purifier is collected, the case of the blood purifier is destroyed, the red color resulting from the leakage of red blood cells in the hollow fiber bundle is visually observed, and the hollow fiber in the blood purifier that has leaked blood The number of was examined.

Example 1
17.0% by mass of polyethersulfone (manufactured by Sumika Chemtex, Sumika Excel (R) 5200P), 3.0% by mass of polyvinylpyrrolidone (Collidon (R) K-90, manufactured by BASF), 77% dimethylacetamide (DMAc). A raw material having a composition of 0% by mass and 3.0% by mass of RO water was put into a tank and mixed, and then uniformly stirred and dissolved at 90 ° C. Next, after reducing the pressure in the system to −500 mmHg using a vacuum pump, the system was immediately sealed and allowed to stand for 15 minutes so that the solvent did not evaporate and the composition changed. This operation was repeated three times to degas the spinning polymer stock solution. The spinning polymer stock solution is passed through a liquid feed line maintained at a temperature of 90 ° C., passed through two kinds of sintered filters of 30 μm and 15 μm in order, and then used as a hollow forming agent from a tube-in orifice nozzle maintained at a temperature of 55 ° C. It was discharged using a 40% by mass DMAc aqueous solution that had been degassed at −700 mmHg for 30 minutes in advance, and after passing through a 600 mm air gap part that was blocked from the outside air by a spinning tube, it was solidified in a 20% by mass DMAc aqueous solution at 70 ° C. Then, it was rolled up in a wet state. The nozzle slit width of the used tube-in-orifice nozzle is an average of 60 μm, the maximum 61 μm, the minimum 59 μm, the ratio of the maximum and minimum slit width is 1.03, the draft ratio of the film forming solution is 1.06, and the dry type The absolute humidity of the part was 0.18 kg / kg dry air. During the spinning process, the roller in contact with the hollow fiber membrane was made of stainless steel whose surface was mirror-finished, and the guides were all made of stainless steel whose surface was textured.

  After wrapping about 10,000 bundles of the hollow fiber membranes, a polyethylene film having a hollow surface on the hollow fiber bundle side surface is wound, and then washed in hot water at 80 ° C. for 30 minutes × 4 times, after the washing is completed. Drying was performed in a nitrogen atmosphere at 40 ° C. The resulting hollow fiber membrane had an inner diameter of 200.2 μm and a film thickness of 31.0 μm. It was 4.5 mass% when the mass ratio of the hydrophilic polymer in a hollow fiber membrane was measured. When the yarn strength of the hollow fiber was measured, the breaking strength was 15.6 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membrane thus obtained and conducting a leak test, no leak due to breakage or breakage of the hollow fiber was observed. The production conditions and evaluation results of the hollow fiber membrane of Example 1 are shown in Table 1.

(Example 2)
A hollow fiber membrane bundle was obtained in the same manner as in Example 1 except that the temperature from the spinning polymer stock solution to the filter was maintained at 75 ° C. The resulting hollow fiber membrane had an inner diameter of 200.1 μm and a film thickness of 30.5 μm. It was 4.5 mass% when the mass ratio of the hydrophilic polymer in a hollow fiber membrane was measured. When the yarn strength of the hollow fiber was measured, the breaking strength was 15.2 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membrane thus obtained and conducting a leak test, no leak due to breakage or breakage of the hollow fiber was observed. Table 1 shows the production conditions and evaluation results of the hollow fiber membrane of Example 2.

(Example 3)
A hollow fiber membrane bundle was obtained in the same manner as in Example 1 except that the temperature from the spinning polymer stock solution to the filter was maintained at 80 ° C. The resulting hollow fiber membrane had an inner diameter of 200.3 μm and a film thickness of 30.5 μm. It was 4.5 mass% when the mass ratio of the hydrophilic polymer in a hollow fiber membrane was measured. When the yarn strength of the hollow fiber was measured, the breaking strength was 15.3 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membrane thus obtained and conducting a leak test, no leak due to breakage or breakage of the hollow fiber was observed. The production conditions and evaluation results of the hollow fiber membrane of Example 3 are shown in Table 1.

Example 4
A hollow fiber membrane bundle was obtained in the same manner as in Example 1 except that the temperature from the spinning polymer stock solution to the filter was maintained at 80 ° C and the nozzle temperature was 45 ° C. The obtained hollow fiber membrane had an inner diameter of 199.9 μm and a film thickness of 30.0 μm. The mass ratio of the hydrophilic polymer in the hollow fiber membrane was measured and found to be 4.4 mass%. When the yarn strength of the hollow fiber was measured, the breaking strength was 15.6 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membrane thus obtained and conducting a leak test, no leak due to breakage or breakage of the hollow fiber was observed. The production conditions and evaluation results of the hollow fiber membrane of Example 4 are shown in Table 1.

(Example 5)
A hollow fiber membrane bundle was obtained in the same manner as in Example 1, except that the temperature from the spinning polymer stock solution to the filter was maintained at 80 ° C and the nozzle temperature was 65 ° C. The resulting hollow fiber membrane had an inner diameter of 201.1 μm and a film thickness of 30.6 μm. It was 4.5 mass% when the mass ratio of the hydrophilic polymer in a hollow fiber membrane was measured. When the yarn strength of the hollow fiber was measured, the breaking strength was 15.1 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membrane thus obtained and conducting a leak test, no leak due to breakage or breakage of the hollow fiber was observed. The production conditions and evaluation results of the hollow fiber membrane of Example 5 are shown in Table 1.

(Comparative Example 1)
A hollow fiber membrane bundle was obtained in the same manner as in Example 1, except that the temperature from the spinning polymer stock solution to the filter was maintained at 40 ° C. The obtained hollow fiber membrane had an inner diameter of 200.5 μm and a film thickness of 30.3 μm. The mass ratio of the hydrophilic polymer in the hollow fiber membrane was measured and found to be 4.6 mass%. When the yarn strength of the hollow fiber was measured, the breaking strength was 12.3 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membranes thus obtained and conducting a leak test, the leak location due to hollow fiber breakage and breakage was an average of 10,000 hollow fiber membrane bundles in the blood purifier. Two were confirmed. The production conditions and evaluation results of the hollow fiber membrane of Comparative Example 1 are shown in Table 1.

(Comparative Example 2)
A hollow fiber membrane bundle was obtained in the same manner as in Example 1, except that the temperature from the spinning polymer stock solution to the filter was maintained at 75 ° C and the nozzle temperature was also 75 ° C. The resulting hollow fiber membrane had an inner diameter of 200.2 μm and a film thickness of 30.5 μm. When the mass ratio of the hydrophilic polymer in the hollow fiber membrane was measured, it was 4.7% by mass. When the yarn strength of the hollow fiber was measured, the breaking strength was 11.5 g per hollow fiber. As a result of assembling a blood purifier using the hollow fiber membranes thus obtained and conducting a leak test, the leak location due to hollow fiber breakage and breakage was an average of 10,000 hollow fiber membrane bundles in the blood purifier. 55 were confirmed. The production conditions and evaluation results of the hollow fiber membrane of Comparative Example 2 are shown in Table 1.

  The polysulfone-based hollow fiber membrane obtained by the production method of the present invention has high strength and water permeability, and can maintain a high yield when producing a blood purifier. Therefore, the method for producing a polysulfone-based hollow fiber membrane of the present invention can economically and stably produce a polysulfone-based hollow fiber membrane having the above characteristics.

Claims (3)

  Polysulfone-based polymer, hydrophilic polymer, aprotic organic solvent, and non-solvent are put into the tank and mixed, and then heated and uniformly dissolved in the spinning polymer solution is filtered with a filter provided in the liquid-feeding line Then, in the method for producing a hollow fiber membrane including the step of discharging from the nozzle and then immersing in a coagulation bath, the temperature of the spinning polymer stock solution from the tank to the filter is in the range of 70 to 95 ° C., and the nozzle discharge temperature is A method for producing a polysulfone-based hollow fiber membrane, which is lower than the temperature and in the range of 40 to 70 ° C.   2. The production of a polysulfone-based hollow fiber membrane according to claim 1, wherein the mass ratio of the hydrophilic polymer in the spinning polymer stock solution is 1 to 20 mass% with respect to the total amount of the polysulfone-based polymer and the hydrophilic polymer. Method.   The method for producing a polysulfone-based hollow fiber membrane according to claim 1 or 2, wherein the hydrophilic polymer is polyvinylpyrrolidone.