KR950007322B1 - Polysulfone hollow fiber membraen for outer pressure - Google Patents

Abstract

The polysulfone hollow fiber membrane composed of 5 layers such as skin layer-finger structure layer-porous network structure-macrovoid layer-porous network structure. Thus, polysulfone resin 200 g was dissolved at 100 degree C in a solution of dimethylformamide 700 g and polyvinylpyrrolidone 100 g, and cooled to 20 degree C to give a spinning solution. The spinning solution was extruded into a inner coagulating solution (water : ethylene glycol : dimethylformamide = 40:10:50) through a duplex tube nozzle and spun at a height of 40 cm, spinning velosity of 30 m/min into an outer coagulating solution (water).

Description

Aromatic Polysulfone Hollow Fiber Membrane for External Pressure Filtration and Manufacturing Method Thereof

1 a) and b) are enlarged cross-sectional photographs of the hollow fiber membranes obtained by the examples of the present invention.

Figure 2 a), b) is an enlarged photograph of the inner surface of the hollow fiber membrane obtained by each embodiment of the present invention.

3 is a correlation diagram of water permeability according to the film thickness of the hollow fiber membrane of the present invention.

The present invention relates to an aromatic polysulfone hollow fiber membrane and a method for manufacturing the same. Specifically, the outer side of the membrane has a dense skin layer composed of fine pores on its outer surface and the inner side has a porous network layer having slit surface pores. Adjacent to this is a skin layer, a ground structure layer, and a porous network, each of which consists of a fin structure layer and a macro layer developed on the outer surface and the inner surface side, and an intermediate layer of the porous network structure where they meet. The present invention relates to a polysulfone hollow fiber membrane and a method for producing the same, which are excellent in permeability, mechanical strength, pressure resistance, and the like, by forming a five-layered structure of a structure layer-co-structure layer-porous network layer.

Hollow fiber membrane modules made of hollow fibers have the largest membrane area per unit volume and provide self-support at the same time as other modules such as the spiral wound type or plate-type. There is a big advantage to miniaturization.

Accordingly, various types of polymers have been studied as hollow fiber membrane materials, but polysulfone resins having excellent heat resistance, acid resistance, alkali resistance, and oxidation resistance have been widely used.

Conventional techniques for hollow fiber membranes made of polysulfone resins include Amicon Co., Ltd. (Japanese Patent Laid-Open No. 49-23183), which has been commercially available for polysulfone hollow fiber membranes, and Japanese Patent Application Publication Nos. 54-145379, 56. -152704, WO 57-82515, EP 0121911, Japanese Patent Application Laid-Open No. 58-91822, WO 58-114702, WO 59-228016, WO 59-228017, WO 59 The methods disclosed in -112027 and 58-132112 can be discussed.

The American Amicon manufacturing method (Japanese Patent Laid-Open No. 49-23183), which belongs to a relatively early technique, uses water as the internal coagulating solution during hollow fiber spinning in the production of polysulfone hollow fiber membranes, so that the manufactured hollow structure A dense skin layer is formed and the outer surface has a single finger-structure in which a cavity of 10 μm or more in diameter lacking a polymer is opened.

This structure has high specificity because there is a large surface structure which is deficient in polymer toward the outer surface of the membrane and there is no dense layer on the outer surface layer, but the mechanical strength is weak and the compaction resistance is small. In addition, by using water with strong coagulation force as the internal coagulating solution during manufacturing, the spinning speed is very slow and the inner surface of the hollow fiber is easily damaged or the hollow fiber during the spinning is easily transmitted.

Due to its structural characteristics, the structural hollow fiber yarns are subjected to filtration from the inner surface of the fiber to the outer surface of the fiber, so that the cake is easily formed on the hollow fiber inner membrane during filtration, and it is difficult to remove the formed cake. It is easy to limit the viscosity of the filtrate to the inner diameter and a larger inner diameter is required for the filtration of the large viscosity solution. In addition, when the operation input is stopped when the plant is operated using the membrane module or the input of the membrane increases, the pores of the membrane are expanded, which requires precise filtration such as ultrapure water manufacturing for semiconductors. It has a hard disadvantage.

Accordingly, a hollow fiber membrane of an external pressure filtration method having an excellent pressure resistance has been proposed since the cake is easily removed and the pressure is applied to the outside of the membrane without being affected by the viscosity of the filtrate solution.

Japanese Patent Application Laid-Open No. 54-145379 discloses a method for producing a hollow fiber membrane having a dense skin layer on the inner and outer surfaces of a separation membrane and adding a surface structure between both surfaces of the membrane by adding an electrolyte aqueous solution to the spinning solution.

Since the structure has a dense skin layer inside and outside, it can be selectively used for the inside and outside filtration method, and has the advantage of high mechanical strength. There is a problem that the productivity is lowered due to the slow spinning speed by using the internal coagulating solution having a strong coagulation force in order to have a dense layer on the actor. In addition, when used as an internal filtration method has a problem according to the actor filtration method described above and has a disadvantage of low permeability because it has one skin layer on the outside. In addition, in the case of using the external filtration method also has a disadvantage of low specificity because the dense skin layer on both sides.

In addition to the above structure, a hollow fiber membrane having a skin layer treated on the inner and outer surfaces of the separator and having a porous network support between both surfaces of the dense layer is disclosed in Japanese Patent Laid-Open No. 56-152704, but still has low water permeability. And the above problems are not solved.

European Patent No. 0121911 discloses a hollow fiber membrane having a porous mesh structure in which the dense skin layer does not exist on the inner and outer surfaces of the hollow yarns, but there is a problem in that the molecular weight of the material to be removed is not well backwashed.

Japanese Patent Laid-Open Nos. 59-228016 and 59-228017 provide a dense surface and a continuous reticulated porous layer on one side of the hollow fiber, and a dense surface and continuous on the other. A hollow fiber membrane which has a high permeability and at the same time has a high mechanical strength by imparting a porous network structure and giving a ground structure different in the radial direction of the membrane in the middle thereof.

In further analysis, the structure disclosed in the above method 1) gives a dense skin layer inside the hollow fiber, gives a porous network structure to the outside, and connects the middle to the cavity of the above ground structure, and 2 ) It can be seen that the inside is made of a porous network structure, the outside is formed of a dense skin layer, and the middle is connected to a ground structure developed from the outside.

Here, the structure of 1) is already a disadvantageous technique of the internal filtration method, and the structure of 2) above has a dense skin layer only on the outside, so the external pressure filtration method on the hollow fiber with the external layer described above is almost provided. have. However, in the method of making the structure 2, high humidity vapor is used as the internal coagulant, but the method has a weak coagulation force and an unstable compressible gas, which requires a stable supply of humidity inside the hollow fiber and also restricts the radiation height. In addition, it is difficult to maintain an even shape of the hollow yarns, and the cutting of the hollow yarns is easy to occur during high-speed spinning, and the inside of the hollow yarns becomes a gas, and there are many problems in practical use such as floating on the water during the spinning of the hollow yarns.

In the preparation of the hollow fiber membrane of the above structure, JP-A-59-112027 and JP-A-58-132112 used benzene, hexane, and paraffin as internal coagulating solution. Since the used water and the organic compounds are not mixed at all, it is difficult to completely solidify the structure, and in order to remove the organic compounds from the product, they have to be post-treated with a solvent such as alcohol or acetone. The swelling properties of the partially impair the structure stability of the hollow fiber membrane.

The present invention has been made to solve all the above problems, the stable production of a polysulfone hollow fiber membrane having a membrane structure and a polysulfone hollow fiber membrane having the structure suitable for an external pressure filtration method with a significant improvement in water permeability and excellent mechanical strength To provide a method.

In order to achieve the above object, the present invention, the outer side of the membrane has a dense skin layer having a fine process on the outer surface, the inner side is a thin porous network layer having a split surface pores (slit) rather than a dense skin layer Skin layer-ground structure layer-porous network formed of the intermediate and intermediate layers of the porous structure formed on the inner surface side and the outer surface side adjacent to each other. Provided are a polysulfone hollow fiber membrane composed of a five-layer structure of a structure layer-co-structure layer-porous network layer.

The invention is described in more detail as follows.

The polysulfone hollow fiber membrane of the present invention has a dense skin layer having a fine pore on the outer surface and the inner surface of the inner surface enlarged in FIG. 2 as shown in the cross-sectional enlarged view of FIG. 1 obtained by the following examples. It consists of a porous network layer having a split surface pores as shown in the figure, and has a finite layer and a macrovoid layer developed on the inner and outer surfaces, respectively, and a porous network formed by The structure consists of five layers of the skin layer, the ground structure layer, the porous network layer, the co-structure layer, and the porous network layer made of the intermediate layer of the structure.

The dense skin layer having a fine pore diameter on the outer surface has an outer surface composed of pores of less than 0.01 µm.

The ground structure in which the pore continuously increases from the outside to the inner side adjacent to the outer skin layer and the ground structure in which the pore continuously increases from the inner side to the outer side in the vicinity of the inner porous layer on the inner surface side are combined with the intermediate layer of the porous network. In the connection, the ground structure is a taper-like structure having a pore diameter of 0.1 μm or less on the inner and outer surfaces and a pore diameter of several μm or more on the inner intermediate layer side, and the porous support of the inner surface layer has a width of 0.01 to 5 μm, A thin support layer of porous network structure having an inner surface having slitting pores of 0.02 to 10 μm in length with a porosity of 40 to 80% and an open pore of 0.01 to 10 μm adjacent thereto is 1 to 10 μm thick. Consists of

In the porous network structure, if the width of the slit-like pores is smaller than 0.01 μm and the length is shorter than 0.02 μm, it is similar to the structure shown in Japanese Patent Application Laid-Open No. 54-1445379, so that the permeability is lowered and the width is larger than 5 μm and the length is 10. If it is longer than the micrometer, the porous network layer becomes coarse and likewise changes its shape in the structure. In addition, if the porosity is less than 40%, the permeability is poor, and if the porosity is greater than 80%, the membrane of the structure is not manufactured.

In addition, the thickness of the intermediate layer of the porous network is preferably 1/20 or more with respect to the overall thickness of the membrane in order to ensure the appropriate mechanical strength and pressure resistance of the membrane, the position of the intermediate layer of the porous network is equidistant from the inside and outside The ratio of the distance from the inner surface to the middle layer and the distance from the outer surface to the middle layer is preferably 1/10 to 10/1. In addition, the pore size of the intermediate layer of the porous network structure is composed of open pores (open-pore) of about 0.1 ~ 10㎛.

The polysulfone hollow fiber membrane having the structure of the present invention is not affected by water permeability depending on the film thickness as can be seen from FIG. 3 below.

This means that the hollow fiber membrane of the present invention has a pore in the outer surface layer of 0.01 μm or less, and the inside has a terrestrial structure and a cavity structure on the taper of several μm or more, and the inner surface layer and the intermediate layer have a large pore size of 10 to 100 times the pore of the outer surface layer. This is because an increase in the thickness of the porous network structure reinforces the mechanical strength of the membrane and does not affect the permeability of the membrane because it is composed of the porous network support formed.

The water permeability of the polysulfone hollow fiber membrane of the present invention having the above structure has a high water permeability and a high mechanical strength of at least 400 × 10 ⁻³ g / cm 2 · min · atm or more.

Next, the polysulfone fiber membrane manufacturing method in this invention is demonstrated.

In manufacturing hollow fiber membranes, it is important to improve the permeability of the prepared membrane and to increase the durability of the membrane structure.

In the related art, researches and developments have been made, and the following methods are well known.

Inorganic salts such as zinc chloride, organic substances such as alcohols, and water-soluble polymers such as polyethylene glycol are added to the film forming solution in an appropriate manner depending on the type of the polymer and the solvent in order to increase the specificity of the film or to increase the viscosity of the spinning solution. It should be easy to remove after film formation.

The film structure has a network structure or a ground structure depending on the concentration of the polymer, the viscosity of the spinning stock solution, the film forming temperature, and the type of the coagulating solution.

In other words, the polymer concentration, the viscosity of the spinning stock solution and the film forming temperature are high, and the progress of coagulation by the coagulating solution is slow to form a sponge-structure, while the polymer concentration, the viscosity of the spinning stock solution and the film forming temperature are low, and the coagulation rate is low. As early as this, a finger-structure is formed.

In general, the polysulfone hollow fiber membrane dissolves polysulfone resin in a high boiling point volatile organic solvent, extrudes a spinning stock solution into a double tubular nozzle and injects an internal coagulant into the hole inside the nozzle to dissipate into the air. It is prepared by solidifying in a coagulation bath of external coagulation liquid or by spinning directly into a coagulation bath of external coagulation solution, followed by complete coagulation and washing with water.

However, if the external coagulant uses only low-viscosity, low-coagulant nonsolvents such as water, the interface where the coagulant is in contact with the spinning solution has a dense skin layer as in Japanese Patent Application Laid-Open No. 54-145379. Therefore, the inner surface such as the structure is not formed and thus the hollow fiber of the structure is not formed. In addition, even when the hollow fiber is manufactured using a solution in which a good solvent of the polysulfone resin is mixed with a low viscosity and low coagulant non-solvent such as water as an internal coagulant, the amount of discharge and When the natural dropping method is selected by the height of the spinning, the inner surface of the manufactured hollow fiber is larger in pore size than in the case of using low coagulation nonsolvent alone, but it does not obtain the above-mentioned split surface pores and is usually 0.01㎛. The inner surface consisting of the following pores is obtained. In addition, if the internal coagulant is prepared with a low-viscosity, low coagulant such as water, a solution of polysulfone resin mixed with a good solvent of the polysulfone resin, and the drawing is carried out while the hollow fiber is manufactured, the internal coagulant is a low point such as water. In addition, when using a solution in which only a good solvent of the polysulfone resin is mixed with a low-solidification nonsolvent, it is difficult to artificially control the size of the pores on the slit of the inner surface of the structure and the shape of the cross section of the structure. For this purpose, it is preferable to add a high viscosity, high coagulant nonsolvent, such as glycerin, to the internal coagulant in three components. In addition, the stretching effect can be reproduced by appropriate mixing of the viscosity, composition, and discharge amount of the spinning solution, and the viscosity, composition, and discharge amount of the internal coagulant, but the method is difficult and limited in selecting experimental variables.

Based on the results of these experiments, we conducted a study to stably reproduce the above structure and came up with the following manufacturing method.

In other words, the spinning stock solution consisting of polysulfone resin and additives and their common solvents is extruded from the double-tubular nozzle, and the good solvent, low viscosity, low coagulation, non-solvent and high viscosity of the polysulfone resin in the holes inside the nozzle. When the high coagulation solution is discharged into the air while injecting the internal coagulating solution mixed with at least two components, it is stretched at a speed faster than the natural dropping speed of the hollow fiber formed by ejecting it from the nozzle when falling into the external coagulation bath. When directly discharging to the external coagulation bath is a method of producing a polysulfone hollow yarn having the above structure by introducing a series of methods to form a hollow fiber by spinning while stretching at a speed faster than the discharge speed of the hollow yarn.

In this case, the poly sulfone resin is selected from an aromatic poly sulfone polymer, an aromatic poly ether sulfone polymer or a chemically modified polymer thereof.

The concentration of polysulfone resin in the spinning stock solution is preferably 10 to 30% by weight to facilitate spinning and to maintain the water permeability of the film after film formation. If the concentration of the polysulfone resin is lower than 10% by weight, the viscosity is low, so that not only spinning is difficult to give the above structure, but the mechanical strength of the prepared membrane is low and higher than 30% by weight, the water permeability of the prepared membrane is lowered.

The solvent of the spinning stock solution is a good solvent of dimethylacetamide, dimethylformamide, N-methyl-2, which is a good solvent for the polysulfone resin in an volatile organic solvent having a boiling point of 100 ° C. or higher to maintain a constant viscosity of the spinning stock solution in the extruder. -Pyrrolidone, dimethylsulfoxide, 2-pyridine, etc. are used alone or in combination of two or more so that the following additives can also be dissolved.

In this invention, additives can be added to the organic solvent together with the polysulfone resin for the purpose of increasing the viscosity of the spinning solution and increasing the permeability of the membrane to make up the spinning stock solution.

The additives include inorganic salts, alcohol compounds, water-soluble polymers, and the like.

The inorganic salt is added as an aqueous solution of calcium carbonate or chloride salt. The amount of addition is preferably 0 to 7% by weight or less in terms of solids relative to the organic solvent.

The alcohol compound may be selected from monohydric alcohols such as methanol and ethanol, polyhydric alcohols such as ethylene glycol, propyl glycol, tetraethylene glycol, glycerin, or derivatives thereof, and may be added up to four times the amount of the polysulfone resin.

However, the more the addition amount, the spinning solution becomes opaque and the spinning is not uniform. When the addition amount is small, the water permeability becomes poor, and considering the radioactivity and water permeability, it is added at a concentration of 0 to 40% by weight with respect to the organic solvent.

The water-soluble high molecular compound not only increases the viscosity of the spinning solution but also is inherent in the polysulfone resin and dissolved in water at the time of washing to increase the permeability of the membrane. It is easy to adjust.

Polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, etc. may be used as the water-soluble high molecular compound, and the amount of the addition is 0-40 in the spinning stock solution in which the viscosity of the added spinning stock solution is 2,000 to 60,000 CPS measured at 21 ° C. It is preferable to set it as the weight% concentration for the permeability of a post-film formation and the ease of spinning.

When the viscosity of the spinning stock solution is lower than 2,000 cps, not only the structure of the film is difficult to form, but also the radioactivity is poor, and the process is difficult, and when the viscosity is higher than 60,000 cps, the spinning is difficult and the uniformity of the film is poor.

In addition, the coagulation of the coagulation liquid in the spinning of the spinning stock solution affects the film structure at the time of film formation.

In other words, if the coagulation force is too small, coagulation does not occur properly and the spinning height cannot be increased, resulting in poor form stability. If the coagulation force is too high, a dense skin layer and a ground structure are formed, but the spinning speed cannot be increased and Surface damage and transfer are apt to occur.

Porous network structure consisting of split pores without inner skin layer with dense inner skin layer on the inner side, and above ground structure and macrovoid layer are developed adjacent to it, and outer surface is developed with dense skin layer adjacent to it In order to produce a hollow fiber membrane in which a ground structure meets in the middle layer of the porous network, the internal coagulation solution should have a higher coagulation rate than the external coagulation solution.

Here, the coagulation value of the coagulation solution is an index indicating coagulation power. The phase transition of 500 ml of a solution obtained by dissolving a mixture consisting of 15 parts by weight of polysulfone and 20 parts by weight of N-methyl-2-pyrrolidone at a concentration of 1% by weight in dimethylacetamide solvent is performed. The amount of coagulant required is expressed in ml. The smaller the value, the higher the coagulation power. The larger the value, the lower the coagulation power.

In the present invention, without forming a dense skin layer on the inner side, the porous network layer and the cavity structure adjacent thereto are formed and the coagulation is easily made so that the coagulation height can be adjusted so that the coagulation value of the internal coagulant is 10-20, and the viscosity is 5-20cps. Range is preferred.

As the coagulant, polydimethyl sulfone is a good solvent for dimethyl acetamide, dimethyl formamide, N-methyl-2-pyrrolidone, 2-pyridine, dimethyl sulfoxide and the like, such as water, ethanol and methanol. Low coagulation of 7-10 viscosity 3-10cps, low viscosity non-solvent and coagulation 20-20, high viscosity of 30-100cps, high viscosity of ethylene glycol, propyl glycol, glycerin, etc. A nonsolvent is properly mixed to prepare a mixed solution having a coagulation rate of 10 to 20 and a viscosity of 5 to 20 cps. Here, when the coagulation value is 20 or more, pores on the slit are formed on the inner surface as described above, but the hollow cavity structure on the inner side is not manufactured, and when the coagulation cost is 10 or less, the pores on the slit are formed on the inner surface. There is a problem such as not.

It is preferable that the external coagulating solution has a solidification value of 13 or less as a mixed solvent or low viscosity of a good solvent, a low viscosity, a low coagulation nonsolvent, and a low coagulation nonsolvent with respect to polysulfone.

When the coagulation value is 13 or more, the pores on the outer surface are so large that a dense layer is not formed, which not only degrades the fractionality of the membrane but also reduces pressure resistance.

The temperature of the external coagulation solution can be variously selected from 0 to 100 ° C. The higher the water temperature, the greater the permeability and the easier removal of residual solvent remaining in the membrane.

In addition, when the non-hollow fiber membrane is radiated into the air and put into the external coagulating solution, phase transition can be controlled by adjusting humidity and spinning height. As for the spinning height in this invention, 0-100 cm was suitable.

If the spinning height is higher than 100cm, the phase transition by the internal coagulating solution proceeds to the outer surface, and the hollow structure developed inside the membrane develops to the outside, so that the dense layer and the ground structure are not formed on the outside, and the hollow fiber membrane of the structure Not formed.

In addition, the drawing speed should be drawn at a speed faster than the natural dropping speed of the spinning liquid and the internal coagulant discharged from the nozzle to the external coagulant bath in the air of the hollow yarn. Should be emitted while At this time, the discharge speed or the natural dropping speed varies depending on the discharge amount of the internal coagulant and the spinning stock solution, the viscosity of the spinning stock solution, the spinning height, and the like. Is made.

When comparing the performance of the hollow fiber membrane produced by the present invention with the conventional fiber membrane, the tensile strength of the existing hollow fiber membrane is 0.2 ~ 0.4g / diner, pressure resistance 2 ~ 4 atm, water permeability 100 ~ 400 × 10 in the ultrafiltration region ^-3 g / ㎠ · min · atm, and the effective internal diameter of the hollow fiber membranes than that inde least 400㎛ in this invention saddle strength 0.3 ~ 0.6g / denier, 4-8 atm pressure resistance permeability 400 ~ 4000 × 10 ^-3 g / Cm 2 · min · atm, having an effective inner diameter of 100 μm or more, which is superior in the permeability and mechanical properties as compared with the conventional hollow fiber membranes.

In addition, in the case of using the manufacturing method of the hollow yarn by the internal coagulant and the stretching of the composition, it was possible to stably manufacture the hollow yarn by the high-speed spinning, which was able to escape the limitation of the low-speed spinning, which is a disadvantage of the manufacturing method of the existing hollow yarn, and thus greatly increased the productivity. .

The polysulfone hollow fiber membrane produced by the above invention has better permeability and mechanical properties than conventional hollow fiber membranes, which is easy to handle and has high separability, and is suitable for external pressure type filtration applications for medical, water purification, and food industries. It is expected to have a great deal of use.

Next, a preferred embodiment of this invention is described.

However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to these examples.

Example 1

200 g of polysulfone resin was dissolved together with 700 g of dimethylformamide and 100 g of polyvinyl pyrrolidone at 100 ° C., followed by cooling at 20 ° C. to prepare spinning stock solution. While extruding the spinning stock solution from a double-tubular nozzle, the inner coagulating solution was mixed with water, ethylene glycol, and dimethylformamide, respectively, at a spinning height of 40 cm and a spinning speed of 30 m / min. The solid sulfone hollow fiber membrane of the present invention having the structures shown in Figs. 1 (a) and 2 (a) was prepared by spinning and solidifying with an external bath using water. The hollow membrane is a hollow fiber having an outer diameter of 1.3 mm and an inner diameter of 0.8 mm as shown in (a) of FIG. 1, and the outer membrane has a dense skin layer and a ground structure adjacent thereto. Similarly, a thin porous network layer having a thickness of 1 µm and a thickness of 1 µm adjacent to a surface of 0.3 µm in width and 1 µm in length, and a cavity having a thickness of 60 µm adjacent to the intermediate layer of the porous network were formed. . The hollow fiber was cut to 30cm in length, and both sides were fixed with epoxy resin, and then the permeability and fractionality were examined. The net permeation rate was 700 × 10 ^{× 3} g / cm 2 · min · atm in external pressure filtration of 1kg / ㎠, and the dex The dextran removal rate in a 0.5% aqueous solution of dexfran was 100%.

The mechanical strength of the membrane was 0.55 g / dinier in tensile strength and the pressure resistance was 4 atm (4 kg / cm 2) or more, and the permeation performance was not deteriorated even after repeated use.

Example 2

150 g of polysulfone resin and 350 g of polyethylene glycol were mixed with 500 g of N-methyl-2-pyrrolidone, dissolved at 100 ° C., and cooled to 20 ° C. to prepare a spinning stock solution.

While compressing the spinning stock solution in a double-tubular nozzle and adding a mixed solvent of ethyl alcohol / N-methyl-2-pyrrolidone = 80/20 as an internal coagulating solution to the inner hole, 100 ° C. water was used as the external coagulant. The external coagulation bath was directly spun at a speed of 50 m / min.

After spinning, the mixture was left at a temperature of 100 ° C. for 12 hours and dried to obtain a polysulfone hollow fiber membrane desired in the present invention.

The fiber membrane is a hollow fiber yarn having an outer diameter of 1.8 mm to 1.0 mm, the outer surface of which is a dense skin layer and a ground structure, and the inner surface thereof is adjacent to the surface of the slit-shaped pores having a width of 0.1 µm and a porous network support layer having a thickness of 2 µm and Adjacent ground and cavity structures developed adjacent to each other, where the intermediate layer of the porous network was present where the ground and cavity structures meet.

As a result of measuring the permeability and mechanical properties of the hollow fiber in the same manner as in Example 1, 0.5% polyvinylpyrrolidone having a pure transmittance of 1800 × 10 ⁻³ g / cm 2 · min · atm and a molecular weight of 95,000 under a pressure of 1 kg / cm 2. In aqueous solution, the removal rate was over 90%, the pressure resistance was 5 atm (5kg / ㎠), and the water permeability was not observed even after repeated use.

Example 3

185 g of polysulfone resin and 15 g of magnesium sulfate were mixed with dimethylacetamide 800, heated to 100 ° C, completely dissolved, and cooled to 20 ° C to prepare a spinning stock solution.

While extruding this spinning stock solution into a double-tubular nozzle, at the same time, a mixed solvent consisting of 25/30/45 water / ethylene glycol / dimethylacetamide, respectively, was injected into the inner hole as an internal coagulant to obtain a spinning height of 20 cm. After spinning for 24 hours and washing with a water bath, a polysulfone hollow fiber membrane having the desired structures of FIGS. 1 (b) and 2 (b) was prepared.

The polysulfone hollow fiber membrane has the same structure as in Fig. 1 (a), the outer diameter is 1.0mm, the inner diameter is 0.5mm, the outer surface is a dense skin layer and the ground structure is developed in the vicinity thereof, and the inner surface is the second structure. As shown in (b), the pores of the slit yarn having a width of 0.5 μm and a length of 1 μm had a porosity of 70%, and a hollow fiber structure having a thickness of 50 μm adjacent thereto was connected to the intermediate layer.

As a result of evaluating the hollow fiber in the same manner as in Example 1, the permeability under 1 atm pressure was 1,000 × 10 ⁻³ g / cm 2 min · atm and the separation rate of 0.2% aqueous solution of polyvinylpyrrolidone having a molecular weight of 40,000 was 90 The mechanical strength was more than 0.5g / denier, the pressure resistance was 5 atm (5kg / ㎠), and the water permeability was not decreased even after repeated use.

As can be seen from the above example, the hollow fiber membrane according to the present invention has a dense skin layer formed by fine pores on the outer surface, and a thin porous network structure formed by slits-like pores on the inner surface side develops a soft cavity structure. It is excellent in mechanical properties and permeability by being connected to the intermediate layer of the porous network with the ground structure on the outer surface side.

Claims (20)

The outer side of the membrane has a dense skin layer with fine porosity on the outer surface and the porous network layer with the inner surface on the slit surface pores, each of which is continuous adjacent to the middle layer from the outer and inner sides adjacent thereto. It is composed of a five-layer structure of skin layer-ground structure layer-porous network layer-co-structure layer-porous network layer where the ground structure and the cavity structure that grows are developed and where the intermediate layer of the porous network structure exists. Polysulfone hollow fiber membrane. The hollow fiber membrane of claim 1, wherein the skin layer comprises pores having a fine pore diameter of less than 0.01 μm. The porous network structure according to claim 1, wherein the ground structure and the cavity structure have a tapered structure in which the pore is continuously increased from the outer skin layer and the inner porous network layer to the intermediate layer of the porous network structure. Hollow fiber membrane, characterized in that connected with. 4. The hollow fiber membrane according to claim 1 or 3, wherein the ground structure has a pore diameter of 0.1 mu m or less at the inner and outer surface side and a pore diameter of 1 to 50 mu m at the inner intermediate layer. The method of claim 1, wherein the intermediate layer of the porous network structure is more than 1/20 of the total thickness of the membrane, the shape is composed of open-pore of 0.01 ~ 10㎛ and the position is from the inner and outer surface to the intermediate layer, respectively Hollow fiber membrane, characterized in that the ratio of the distance of 1/10 ~ 10/1. The porous support of claim 1, wherein the porous support on the inner surface has an inner surface having slit-like pores having a width of 0.01 to 5 μm and a length of 0.02 to 10 μm having a porosity of 40 to 80%, and open pores of 0.01 to 10 μm adjacent thereto. A hollow fiber membrane, characterized in that the porous network support layer made of (open pore) is not less than 1㎛ 10㎛ thick. The spinning stock solution consisting of polysulfone resin, a participant, and a common solvent thereof is extruded from a double-tubular nozzle, and a good solvent of the polysulfone resin, a low viscosity low coagulation cost nonsolvent, and a high viscosity high coagulation cost are formed in the hole inside the nozzle. When the non-solvent is discharged into the air while injecting the internal coagulating solution mixed with at least two components, it is stretched at a speed faster than the natural dropping speed of the hollow fiber formed by discharge from the nozzle when it is dropped into the external coagulation bath, or directly outside the coagulation bath. A method for producing a polysulfone hollow fiber membrane having a structure as set forth in claim 1, characterized in that a series of methods of forming hollow fibers by spinning while stretching at a speed faster than the discharge speed of hollow yarns. The method of claim 7, wherein the poly sulfone resin is selected from an aromatic poly sulfone polymer, an aromatic polyethesulfone polymer, or a chemically modified polymer thereof, wherein the poly sulfone resin is 10 to 30% by weight in the spinning stock solution. It is characterized in that the concentration of. The method of claim 7, wherein the solvent of the spinning stock solution is a good volatile solvent for polysulfone as a nonvolatile organic solvent having a boiling point of 100 ° C or higher. The solvent of the spinning solution is selected from dimethyl acetamide, dimethyl formamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, 2-pyridine according to claim 7 or 10, characterized in that is used. How to. 8. The method of claim 7, wherein the additive is added to at least one spinning stock solution as an inorganic salt, an alcohol compound, or a water-soluble polymer. The method according to claim 11, wherein the inorganic salt is added to the spinning stock solution with calcium carbonate, zinc chloride or the like at a concentration of 0 to 7% by weight. The method according to claim 11, wherein the alcohol compound is selected from one or more of monohydric alcohols such as methanol and ethanol or derivatives thereof, and a concentration of 0 to 40% by weight is added in the spinning solution. The method of claim 11, wherein the water-soluble polymer is selected from polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone and added in a concentration of 0 to 40% by weight in the spinning stock solution. 8. The method of claim 7, wherein the viscosity of the spinning stock solution is 2,000 to 60,000 center pore. The method of claim 7, wherein the internal coagulating solution is a mixture of at least one component of the low viscosity, low coagulation non-solvent and high viscosity, high coagulation non-solvent of the good solvent of polysulfone, the coagulation cost 10 The method characterized by falling in the range of -20 and a viscosity of 5-20cps. 8. The method according to claim 7, wherein the external coagulating solution is a mixed solvent of a good solvent and a low viscosity and low coagulation nonsolvent with respect to water or polysulfone. 18. The method according to claim 7 or 17, wherein the temperature of the external coagulation liquid is 0 ° C to 100 ° C. 8. The method of claim 7, wherein the radiation height is 0-1 m. 8. The method according to claim 7, wherein the stretching speed is 1 to 5 times the discharge speed and the natural falling speed.