JP2000140589A - Porous polysulfone film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent bacterial lump pieces contained in a dialysis liquid from penetrating into the inside of a hollow fiber film which consists of a polysulfone resin and a hydrophilic polymer and has a dense layer at the inner surface side and a porous part on the outer surface by setting the ratio of pores each having a specified pore area, the average pore area, and the ratio of opening, each in a specified ratio. SOLUTION: In a hollow fiber film which is suitably used for blood dialysis, blood filtration, and blood dialysis filtration, consists of a polysulfone resin and a hydrophilic polymer, and has a dense layer at the inner surface side and a porous part on the outer surface, the ratio of opening of the porous part on the outer surface is set at 10-30%; the ratio of pores each having a pore area of 0.5 μm2 or higher, at 10% or lower; the ratio of pores each having a pore area of 0.1 μm2 or lower, at 75% or lower; and/or the average pore area on the outer surface, in a range of 0.05-0.35 μm2. Thus, hollow fibers are prevented from adhering to each other, and simultaneously the penetration of bacterial lump pieces from a contaminated dialysis liquid into the inside of the film can be inhibited. Polyvinylpyrrolidone is preferable as the hydrophilic polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical separation membrane for removing blood wastes by extracorporeal circulation, and relates to blood purification, particularly hemodialysis for substituting renal function.
It is used in the fields of hemofiltration and hemodiafiltration.

[0002]

2. Description of the Related Art In recent years, dialysis therapy using a dialysis membrane has been performed on a patient having a low ability to remove waste products in blood due to a decrease in renal function, thereby extending the life of the patient. On the other hand, with such prolonged dialysis therapy, a complication called dialysis amyloidosis has appeared. It is a disease in which fiber proteins called amyloid deposit on ligaments, tendons, joints, and the like, causing various clinical symptoms. Β One protein ₂ constituting the amyloid - since microglobulin have been identified, removal of these low molecular proteins is one of the therapeutic target, increased the market demand for high-performance dialysis membrane to enable it . The properties required for the high-performance dialysis membrane, beta ₂ - high removal performance of low-molecular proteins typified microglobulin, and is an excellent biocompatibility, a synthetic polymer as a membrane material satisfying these Polysulfone-based resins have attracted attention, and the development of high-performance dialysis membranes mainly composed of polysulfone-based resins has been actively promoted.

[0003] However, polysulfone resins have high hydrophobicity and, as they are, have poor water wettability, so that they cannot exhibit sufficient filtration performance. Furthermore, when used in the field of blood purification as in the present invention, it is necessary to suppress the activation of the blood coagulation system, and a hydrophilic agent such as a hydrophilic polymer or glycerin is added to make the membrane surface hydrophilic. Often done. Since these hydrophilizing agents are present on the surface of the membrane, the hydrophilizing agent serves as a glue during drying in the manufacturing process, and sticks between adjacent films, resulting in poor molding due to poor penetration of the potting agent. was there.

[0004] Attempts to remedy this drawback include, for example, Japanese Patent Application Laid-Open No. 7-28986 discloses a technique for reducing the contact area between adjacent membranes by forming a large opening in the outer surface of a hollow fiber membrane.
3. However, while the use of endotoxin cut filters has dramatically improved the quality control of dialysate water, dialysate contamination due to structural factors such as dialysate supply couplers has still occurred, and bacteria that have detached from the coupler during use have been used. There was a possibility that lumps entered the porous portion inside the membrane from the opening on the outer surface of the membrane. In addition, in these high-performance dialysis membranes, endotoxin released from the bacterial mass due to physical shock at the time of invasion may permeate the dense layer, migrate to the blood side, and stimulate the living body.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polysulfone-based porous membrane which does not cause molding defects due to membrane sticking during production and does not allow the bacterial mass contained in the dialysate to enter the inside of the membrane. With the goal.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have been made of a polysulfone-based resin and a hydrophilic polymer. In the hollow fiber membrane having a portion, when the abundance ratio of the specific pore area, the average pore area, and the opening rate are in the specific ranges, not only can the fixation of the hollow fibers be prevented, but also from the contaminated dialysate. The present inventors have found that invasion of bacterial mass pieces into the inside of the membrane can be prevented at a high rate, and have completed the present invention. That is, the present invention is a hollow fiber membrane comprising a polysulfone-based resin and a hydrophilic polymer, a dense layer on the inner surface side, and an opening on the outer surface, wherein the opening ratio of the opening on the outer surface is lower. 10
30%, the abundance of pores having a pore area of 0.5 μm ² or more on the outer surface is 10% or less, and the pore area is 0.1 μm ²
And the average pore area on the outer surface is 0.05 to 0.35 μm.
The present invention relates to a polysulfone-based porous membrane characterized by having m ² .

The membrane of the present invention comprises a polysulfone resin and a hydrophilic polymer. The main component of the membrane is a polysulfone resin, which is represented by the following chemical structural formula (1) or (2). It consists of a repeating unit. In addition, a so-called polysulfone derivative in which a functional group or an alkyl group is bonded to an aromatic ring is also included in the scope of the present invention. Ar in the formula represents a para-substituted divalent phenyl group. -O-Ar-C (CH3) 3-Ar-O-Ar-SO3-Ar- (1) -O-Ar-SO3-Ar- (2)

[0008] The second component constituting the membrane is a hydrophilic polymer, and is added mainly for the purpose of making the membrane hydrophilic and forming pores. The hydrophilic polymer is preferably dissolved in a common solvent with the polysulfone-based resin, and is preferably a vinyl-based polymer in terms of compatibility, for example, polyvinylpyrrolidone, polyethylene glycol, polyamide, polyvinyl alcohol,
It can be selected from ethylene vinyl alcohol copolymer. Among them, polyvinylpyrrolidone is most preferable because it has a moderate affinity with the polysulfone-based resin and can remain on the membrane surface and contribute to antithrombosis and filtration performance due to hydrophilicity. The content of these hydrophilic polymers may be 3 to 12 as long as the membrane surface can be finally made hydrophilic.
Weight percent is sufficient. More preferably, it is 5 to 9% by weight. Therefore, the remaining portion of the membrane, 88-97% by weight, is polysulfone-based resin.

The structure of the porous membrane of the present invention has an inner diameter of 80 to 80.
It is a hollow fiber having a hollow part of 400 μm and a film part with a thickness of 35 to 85 μm, and has both sufficient pressure resistance and tensile strength for blood purification applications. If the inner diameter is smaller than this, blood flow resistance increases and blood flow velocity cannot be secured,
Even if the size becomes larger than necessary, the efficiency of mass transfer in the blood decreases, leading to a decrease in the therapeutic effect. On the other hand, if the film thickness is too thin, the strength cannot be maintained, causing crushing or leaking. If the film thickness is too thick, the mass transfer resistance in the film increases and the permeation performance decreases. This hollow fiber membrane has an asymmetric structure consisting of a dense layer having a separation function on the inner surface side and a dense layer as a support on the outer surface side, and has a controlled pore distribution on the outer surface in contact with the dialysate. It has the opening part which has the effect of the present invention.

[0010] The pore distribution of the membrane of the present invention is quantified by image analysis of a scanning electron micrograph of the outer surface of the dried membrane. Specifically, after washing the pore-diameter retaining material and the filling liquid attached to the film with water, the film freeze-dried from cold ethanol is silver-deposited, and a photograph of the outer surface of the film at a magnification of 6000 is taken with an electron microscope. This is printed in a size of 90 mm x 70 mm, the entire area of the photograph is taken into a personal computer using image analysis software, and the image is binarized to determine the hole area for each hole on the outer surface. Can be. as a result,
The present inventors have a certain relationship between the distribution of pore area and the average pore area and the amount of mold infiltration in the dialysate and moldability,
And there is a certain relationship between the open area ratio and moldability,
We found that there was a need to control both.

First, the abundance ratio of holes having a specific hole area will be described. The abundance ratio in the present invention refers to the ratio of the total number of holes having an arbitrary hole area to the total number of holes in a captured image. It is defined as a percentage and is given by the following equation (3). In addition, 10 pixels or less were considered as noise and excluded from the count. Abundance (%) = (total number of holes with arbitrary hole area / total number of holes in image) × 100 (3)

Normally, a part of the dialysate flows from the pores on the outer surface of the membrane into the porous portion inside the membrane. In some cases, part of the endotoxin released from the bacterial mass due to physical shock at the time of invasion may pass through the dense layer and move to the blood side. In general, the size of the cells is 1
Since the pore area is 0.5 μm ² or less, penetration of bacterial mass pieces hardly occurs. To effectively block the invasion of Kinkatamarihen is the abundance of open area 0.5 [mu] m ² or more holes 1
It is necessary to keep it to 0% or less, and it is more preferred to keep it to 7% or less. Most preferably, it is 5% or less. On the other hand, if the number of holes having a small hole area is too large, problems in molding are likely to occur. In particular, the pore area is 0.1 μm ²
When the number of the following holes increases, fixation occurs between adjacent membranes, and incomplete separation of the inside and outside of the hollow fiber membrane due to poor penetration of the potting agent between the membranes. In order to eliminate molding defects due to such adhesion, it is necessary to reduce the abundance ratio of holes having a hole area of 0.1 μm ² or less to 75% or less. More preferably 60
%, Most preferably 45% or less.

Second, the average pore area will be described. The average pore area in the present invention is defined as the average value of the pore areas of all the pores in a captured image, and is given by the following equation (4). Can be Again, less than 10 pixels were considered as noise and excluded from the count. Average pore area = sum of pore areas in image / total number of pores in image (4) The average pore area is related not only to the invasion of bacterial mass pieces but also to the moldability, particularly to the adhesion between membranes. This is because the smaller the smaller, the stronger the tendency of the adjacent films to adhere to each other, and the more likely the molding failure is. Conversely, the larger the size, the more intrusion of the bacterial mass occurs, so it is necessary to keep the size within the range of 0.05 to 0.35 μm ² . It is more preferably in the range of 0.10 to 0.30 μm ² , and most preferably in the range of 0.10 to 0.20 μm ² .

On the other hand, in addition to these parameters, the porosity of the outer surface is also an important parameter in molding. The aperture ratio in the present invention is defined as a percentage of the sum of the aperture area of the aperture portion with respect to the area of the captured image, and is given by the following equation (5). Again, less than 10 pixels were considered as noise and excluded from the count. Perforation rate (%) = (total of perforated area of perforated part / area of captured image) × 100 (5)

The porosity greatly contributes to the adhesion of the films. If the porosity is small, the contact area between the adjacent films increases, and the film sticks. If the porosity is severe, the whole bundle sticks in a rod shape. There are even things. For this reason, it is necessary to secure a hole opening rate of 10% or more. However, if the opening ratio is unnecessarily increased, the film is bent in the longitudinal direction, that is, the stiffness is impaired. As a result, molding failure due to the yarn flow in the potting portion during molding frequently occurs. The upper limit of the porosity should be 30% in order not to impair the strength of the waist, and therefore, the range of the porosity of the outer surface needs to be 10 to 30%. A more preferred range is 15 to 30%.

Next, as a method for producing the polysulfone-based porous membrane of the present invention, a case where polyvinylpyrrolidone (hereinafter, referred to as PVP) is used as a hydrophilic polymer will be exemplified. The stock solution used for manufacturing the membrane has three basic components, a polysulfone resin, PVP, and a solvent. The concentration of the polysulfone-based resin as the composition of the film-forming stock solution may be within a range that has a viscosity capable of forming a film and can exhibit characteristics as a film. %. If it is less than 10% by weight, sufficient strength as a film cannot be obtained,
If the content is more than 10% by weight, the density of the polymer increases, the number of through holes decreases, and sufficient permeability cannot be obtained, which is not practical.
These polysulfone resins have a weight average molecular weight of 1 to 1.
50,000 are commercially available and it is sufficient to use them. There is no particular limitation.

PVP is mainly used for forming pores in a polysulfone-based porous membrane and for remaining the polymer to impart hydrophilicity. Surprisingly, the inventors of the present invention have found that the ratio of PVP to the polysulfone-based resin is involved in pore formation, particularly pore formation on the outer surface of the membrane. Although the detailed principle is still unknown, it seems that the main factor is that the molecular size of PVP is much larger than that of the polysulfone resin. That is,
When the ratio of PVP to the polysulfone resin becomes lower within a certain range, the viscosity of the discharged stock solution decreases, the microphase separation speed due to the diffusion of PVP increases, and the fusion of PVP vesicles progresses. As a result, a small number of holes having a relatively large area are formed. Conversely, when the proportion of PVP increases, the fusion speed of PVP vesicles decreases due to an increase in the viscosity of the stock solution, while the deposition of polysulfone-based resin proceeds, and as a result, a large number of small-area pores are formed. It is considered that the porosity is also increased.

In the case where pores having a large area are present on the outer surface of the membrane as described above, even if the number of pores is small, bacterial mass in the dialysate enters the membrane through the pores, and is caused by physical shock at the time of penetration. There is a possibility that the released endotoxin passes through the dense layer and moves to the blood side. Conversely, if the number of holes having a small area increases, the adhesion between the films increases, or the porosity becomes too high, and the stiffness of the film decreases, resulting in poor molding. Therefore, in order to satisfy the above, the ratio of PVP to the polysulfone-based resin in the film-forming stock solution was 0.25 to 0.25.
0.45 is preferred, and 0.30 to 0.40 is more preferred.

Since various types of PVP are commercially available according to their molecular weight, they may be used without any particular limitation. However, as mentioned above, it is important for the opening of the outer surface and also has the purpose of making the membrane surface hydrophilic. From this viewpoint, it is preferable that the material easily remains on the film surface at the time of film formation. The larger the molecular weight is, the more the tendency tends to be. Therefore, it is preferable to use a material having a weight average molecular weight of at least 100,000 or more. The solvent is a solvent that dissolves both the polysulfone resin and PVP, and is selected from dimethylsulfoxin, N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, sulfolane, dioxane, and the like. However, each of these combinations is optional. Also, a small amount of water or salts can be added for the purpose of controlling the solidification rate.

In order to obtain a polysulfone-based porous membrane using the membrane-forming stock solution comprising the above system, a known dry-wet method may be used. The film forming stock solution and the internal coagulation solution are simultaneously discharged from an annular nozzle (double spinneret) having a double tube structure kept at 30 to 60 ° C., and introduced into a coagulation bath. At this time, the nozzle is caused to travel in the air before being introduced from the nozzle discharge into the coagulation bath. The air running length of the discharge surface of this nozzle and the surface of the coagulation bath is usually 10 to 100.
cm, particularly preferably 30 to 85 cm. If it is shorter than 10 cm, the solidification layer is formed on the outer surface as a result of reaching the coagulation bath with incomplete coagulation, so that the film of the present invention cannot be obtained. On the other hand, if it exceeds 100 cm, the yarn may oscillate and the incompletely coagulated yarn may adhere to each other, which is not preferable in the production process.

The atmosphere of the aerial traveling section is also important for achieving the present invention, and the periphery of the traveling section is enclosed by a hood, and the interior is kept wet. The wet state utilizes water vapor generated from the lower coagulation bath, and the temperature of the coagulation bath is set at 30.
It is sufficient to adjust the temperature in the range of -70 ° C and saturate the inside of the hood with steam. More preferably, it is in the range of 45 to 60 ° C. As for the internal coagulation liquid, it is better to use a low coagulation liquid than a liquid having a high coagulation property with respect to the spinning solution. N, N- as solvent
It is selected from dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and the like. The preferred composition of the internal coagulation liquid is 5 to 40% by weight of solvent and the balance water. If the proportion of water is further increased, sufficient water permeability may not be achieved as a membrane. More preferably, the solvent is 10 to 25.
% By weight.

The hollow fiber solidified as described above has an asymmetric porous structure having a dense layer on the inner surface side and an opening on the outer surface side. After winding this hollow fiber membrane into a cassette and cutting it into a fixed bundle length, the remaining solvent is washed with water, and then, for example, a glycerin aqueous solution is adhered as a pore diameter retaining agent before drying treatment, and the resulting mixture is heated to 70 to 80 ° C. If the drying treatment is performed for 10 hours or more, the film of the present invention can be obtained. When using the membrane, both ends are potted with polyurethane or the like, molded into a module having a predetermined membrane area, and sterilized if necessary. Modulation may be performed according to a known method, and is not particularly limited. The sterilization method may be selected from known methods according to the application. For example, treatment such as ethylene oxide gas sterilization, high-pressure steam sterilization, and radiation sterilization may be performed.

[0023]

Next, the present invention will be described in detail with reference to Examples and Reference Examples, but the present invention is not limited thereto. Various numerical values used in the examples were measured by the following procedures. (Pore area on the outer surface, abundance ratio of pores, and porosity) The membrane was washed with running water for 1 hour and freeze-dried with ethanol containing dry ice. After fixing this film on a dedicated sample stage and depositing silver, a photograph of the outer surface at a magnification of 6000 times was taken with a scanning electron microscope (S-2460N manufactured by Hitachi, hereinafter referred to as SEM). In image processing, the photograph (90 mm × 70 mm) was captured by an image scanner, and the processing area (Color Magician 7, version 1.0, manufactured by Kosin Graphic Systems Ltd.) was used to cover the entire photograph with a resolution of 320. The brightness was 2, 256 gradations. This image is processed by processing software (N
Binarization by IH image, version 1.57)
The hole area of each hole was calculated. Note that an image of 10 pixels or less was regarded as noise and excluded from counting. In addition, calibration was performed by simultaneously measuring true circular holes in a membrane filter (manufactured by Millipore: Isopore, pore diameter 2 μm) having uniform pore diameters by electron beam irradiation.

(Bacterial Lump Reverse Filtration Test) A dialysate (AK-Solita DL, manufactured by Shimizu Pharmaceutical Co., Ltd.) was prepared using an in-house prepared high bacterial mass-containing aqueous solution. The bacterial mass used was substituted by measuring the endotoxin content. A circuit containing a dialysate contaminated with a bacterial mass having an endotoxin concentration of 15800 EU / liter was connected to the inlet of the module dialysate, and the outlet of the dialysate was plugged. The circuit was connected to the blood outlet side of the module, and the blood inlet side was plugged. A pump was set in the dialysate inlet circuit, and 2 liters were back-filtered to the blood outlet side at a flow rate of 200 cc / min and discharged, and then the back filtrate was collected from the blood outlet side. The amount of endotoxin contained in the collected back-filtration solution was quantified by Endospecy (manufactured by Seikagaku Corporation: ES-50 set), and the back-filtration rate was calculated from the following equation (6). In the equation, C0 represents the endotoxin concentration in the dialysate, and C1 represents the endotoxin concentration in the back filtrate. Reverse filtration rate (%) = (C1 / C0) × 100 (6)

[0025]

Example 1 Polysulfone resin (Amoco: P
-1700) 17% by weight, PVP (manufactured by BASF: K9
0) 7% by weight of N, N-dimethylacetamide (hereinafter, referred to as
76 wt% (referred to as DMAC) was stirred and dissolved at 50 ° C. for 8 hours, followed by defoaming to obtain a film forming stock solution. Internal coagulation liquid is DMAC15
% By weight and 85% by weight of water. The film forming stock solution and the internal coagulation solution were discharged from a double spinneret kept at 55 ° C., and introduced into a coagulation bath through a 60 cm air-running section sealed with a hood. The coagulation bath is warm water of 52.5 ° C,
The inside of the hood was saturated with steam. After passing through a coagulation bath, the membrane wound around the cassette was washed with hot water. Further, a 15% by weight aqueous glycerin solution was adhered as a pore diameter retaining agent, and dried at 70 ° C. for 12 hours. The obtained film was molded into a module having a film area of 1.5 m ² using polyurethane, filled with water, and irradiated with 25 KGy of γ rays. As a result of image processing the SEM photograph showing the film 1 on the basis of 3.0% the percentage of open area 0.5 [mu] m ² or more holes in the outer surface, the percentage of open area 0.1 [mu] m ² or less holes 4
2.9%, an average pore area of 0.16 μm ² and a porosity of 1
It was 5.5%. This film had no sticking and had good moldability. In addition, since the endotoxin concentration in the back filtrate was below the detection limit (9.0 EU / liter or less), virtually no intrusion was observed.

[0026]

[Example 2] Polysulfone resin (Amoco: P
-1700) 17% by weight, PVP (manufactured by BASF: K9
0) 4.5% by weight of DMAC and 78.5% by weight of DMAC are mixed,
The mixture was stirred and dissolved at 50 ° C. for 8 hours and defoamed to obtain a film forming stock solution. The internal coagulation liquid was prepared by mixing 20% by weight of DMAC and 80% by weight of water. Air running length 45cm, coagulation bath temperature 65
A dried film was obtained under the same conditions as in Example 1 except that the temperature was changed to ° C. The obtained film was molded into a module having a film area of 1.5 m ² using polyurethane, filled with water, and irradiated with 25 KGy γ rays. As a result of performing image processing based on the SEM photograph in the same manner as in Example 1, the ratio of pores having a pore area of 0.5 μm ² or more on the outer surface was 9.3%, and the proportion of pores having a pore area of 0.1 μm ² or less was found. 39.6%, the average pore area was 0.19 μm ² , and the porosity was 10.6%. This film also did not adhere and could be molded well. In addition, since the endotoxin concentration in the reverse filtrate was below the detection limit (9.0 EU / liter or less), virtually no intrusion was observed.

[0027]

[Comparative Example 1] Polysulfone resin (manufactured by Amoco: P
-1700) 17% by weight, PVP (manufactured by BASF: K9
0) 9.0% by weight of DMAC and 74.0% by weight of DMAC are mixed,
The mixture was stirred and dissolved at 50 ° C. for 8 hours and defoamed to obtain a film forming stock solution. The internal coagulation liquid was prepared by mixing 20% by weight of DMAC and 80% by weight of water. Air running length 60 cm, coagulation bath temperature 55
A dried film was obtained under the same conditions as in Example 1 except that the temperature was changed to ° C. The obtained film was molded into a module having a film area of 1.5 m ² using polyurethane, filled with water, and irradiated with 25 KGy γ rays. This membrane has a pore area of 0.5 μm ^{2 on the} outer surface.
The proportion of the above holes is 0.8%, the proportion of the pores having a pore area of 0.1 μm ² or less is 88.5%, and the average pore area is 0.03 μm.
m ² , and the porosity was 3.3%. After drying, the film was strongly adhered and could not be molded as it was. After repair and molding, the bacterial mass was subjected to a reverse filtration test. The endotoxin concentration in the reverse filtrate was below the detection limit (9.0 EU).
Per liter or less), and virtually no intrusion was observed.

[0028]

[Comparative Example 2] Polysulfone resin (Amoco: P
-1700) 17% by weight, PVP (manufactured by BASF: K9
0) 3.5% by weight and 79.5% by weight of DMAC are mixed,
The mixture was stirred and dissolved at 50 ° C. for 8 hours and defoamed to obtain a film forming stock solution. The internal coagulation liquid was prepared by mixing 15% by weight of DMAC and 85% by weight of water. Air running length 45cm, coagulation bath temperature 25
A dried film was obtained under the same conditions as in Example 1 except that the temperature was changed to ° C. The obtained film was molded into a module having a film area of 1.5 m ² using polyurethane, filled with water, and irradiated with 25 KGy γ rays. This membrane has a pore area of 0.5 μm on the outer surface.
The ratio of ^two or more holes is 47.5% and the hole area is 0.1 μm ²
The ratio of the following pores is 18.8%, and the average pore area is 0.59.
μm ² and the porosity was 35.8%. There was no film sticking after drying and molding was possible, but yarn flow was observed over the entire potting portion. When the fungus back filtration test was performed,
The back filtration rate was 0.13%, and back filtration of endotoxin due to invasion of bacterial mass was observed.

[0029]

According to the present invention, the polysulfone porous membrane of the present invention does not cause molding failure due to membrane sticking during the production, and the bacterial mass contained in the dialysate penetrates into the inside of the membrane, and the endotoxin is reversely filtered. Since it does not occur, it can be suitably used in the blood purification field.

[Brief description of the drawings]

FIG. 1 shows an SEM photograph (magnification: 6000 times) of a film obtained in Example 1 as an example of a film obtained by the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C077 AA05 BB01 BB02 KK09 LL05 LL14 LL16 LL17 NN20 PP15 PP18 4D006 GA13 LA06 MA01 MA23 MA25 MA26 MA31 MA33 MA40 MC33 MC34 MC40X MC45 MC54 MC62X MC83 MC88 NA04 NA10 NA27 NA28 NA64 NA64 NA09 PB54 PC41 PC47

Claims (2)

[Claims] 1. A hollow fiber membrane comprising a polysulfone-based resin and a hydrophilic polymer, having a dense layer on the inner surface side and an opening on the outer surface, wherein the opening ratio of the opening on the outer surface is 10%. ~
30%, the abundance of pores with a pore area of 0.5 μm ² or more on the outer surface is 10% or less, and the abundance of pores with a pore area of 0.1 μm ² or less is 75% or less, and / or The average pore area on the outer surface is 0.05 to 0.35 μm
^2. A polysulfone-based porous membrane, which is ² . 2. The polysulfone-based porous membrane according to claim 1, wherein the hydrophilic polymer is polyvinylpyrrolidone.