JPS61268302A - Aromatic polysulfone composite semipermeable membrane and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain an aromatic polysulfone composite semipermeable membrane improved in permeation stability, pressure resistance and flexibility, by uniformly adhering a polyvinyl alcohol type polymer subjected to water-insolubilization treatment to the surface of a porous membrane made of aromatic polysulfone. CONSTITUTION:A hollow porous membrane comprising aromatic polysulfone is immersed in an aqueous solution of polyvinyl alcohol to be impregnated therewith and the impregnated one is dried to be immersed in a solution containing polyvalent aldehyde such as glutaraldehyde and an acid catalyst such as sulfuric acid to apply water-insolublization treatment to polyvinyl alcohol. Thus obtained composite semipermeable membrane has water-insoluble polyvinyl alcohol amount uniformly adhered not only to the surface thereof but also to the inner surfaces of the fine pores thereof and is provided with a surface made hydrophilic and, therefore, the adsorption of a solute by the surface of said membrane is reduced and, because the membrane is reinforced by the water-insoluble polyvinyl alcohol adhered to the inner surfaces of fine pores, said membrane is excellent in mechanical strength and, in the case of a hollow membrane, the internal pressure resistance thereof is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an aromatic polysulfone composite semipermeable membrane, and more particularly to an aromatic polysulfone composite semipermeable membrane with excellent permeability stability and pressure resistance strength.

(Prior art) In recent years, semipermeable membranes have been used for desalination of seawater, production of ultrapure water, purification, concentration, and sterilization in the pharmaceutical and food industries, treatment of industrial and domestic wastewater, membrane materials for artificial organs, etc. It is widely used in extremely diverse fields, and semipermeable membranes with various characteristics are manufactured depending on these uses. However, conventionally known semipermeable membranes are still unsatisfactory in permeation performance and other properties depending on their use. For example, semipermeable membranes made of cellulose esters have conventionally been used as reverse osmosis membranes and artificial organ materials, but they have poor microbial resistance, chemical resistance, heat resistance, solvent resistance, and the like.

For this purpose, in particular, as a semipermeable membrane with excellent microbial resistance, heat resistance, and chemical resistance, for example, JP-A-49-2318
As described in Publication No. 3 and Japanese Patent Application Laid-open No. 16378/1983, semipermeable membranes made of aromatic polysulfone have been proposed, and some have already been put into practical use. However, although aromatic polysulfones generally have the above-mentioned excellent properties, they are relatively hydrophobic and have low affinity for water, so they inherently have low water permeability when treating aqueous liquids. In addition to being low, solutes are easily adsorbed on the membrane surface and contaminated, so depending on the properties of the aqueous liquid to be treated, the permeation performance may decrease rapidly over time.

Furthermore, hollow fiber membranes made of aromatic polysulfone have the important problem of low internal pressure strength due to the particularly brittle nature of aromatic polysulfone, which inevitably limits the applications and conditions of use. .

For example, a tubular composite semipermeable membrane is usually manufactured by forming an aromatic polysulfone semipermeable membrane on a reinforcing material such as a nonwoven fabric to form a reinforcing membrane, and processing this into a tubular shape. This reinforcing membrane generally has poor flexibility, and cracks may occur in the reinforcing membrane during pipe manufacturing.
There is a need for aromatic polysulfone reinforced membranes that provide flexibility.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems in aromatic polysulfone semipermeable membranes, and in particular, to provide an aromatic polysulfone membrane with improved permeation stability, pressure resistance, and visibility. The object of the present invention is to provide a composite semipermeable membrane and a method for manufacturing the same.

(Structure of the Invention) The aromatic polysulfone composite semipermeable membrane according to the present invention has a polyvinyl alcohol-based polymer treated to be water insolubilized on the surface of the porous membrane made of aromatic polysulfone and on the inner surface of the micropores of this porous membrane. It is characterized by being uniformly adhered.

Such an aromatic polysulfone composite semipermeable membrane according to the present invention comprises:
Preferably, according to the present invention, a porous membrane made of aromatic polysulfone is coated or impregnated with an aqueous solution of a water-soluble polyvinyl alcohol polymer containing an inorganic alkaline compound.

Thereafter, the water-soluble polyvinyl alcohol polymer is heated and dried to make it water-insolubilized, and the water-insolubilized polyvinyl is applied to the surface of the porous membrane and the inner surface of the micropores of the porous membrane. It is manufactured by depositing an alcohol-based polymer almost uniformly.

Method for manufacturing a ruhon composite semipermeable membrane.

The aromatic polysulfone used in the present invention is preferably a polymer having repeating units represented by the following general formula (I) or (IT).

-^-302-8-0-(8-RIl-A-X), -(
I)-8-3Q2-A-3o2-^-0-(TI
) (However, A each represents the same or different aromatic group, R represents a divalent organic group, X represents 0 or S02,
m and n each represent 0 or 1).

For example, aromatic polysulfones having any of the following repeating units are easily available and can be suitably used in the present invention.

In order for the aromatic polysulfone composite semipermeable membrane according to the present invention to have practical permeability and strength, the aromatic polysulfone as described above must be used in 1. 0.2 to 1.0 g/100 ml of dimethylformamide solution at 25°C.
Reduced viscosity η-p/ of 0, preferably 0.25 to 0.80
c (hereinafter, the measurement conditions for reduced viscosity are the same).

In the present invention, the porous membrane made of aromatic polysulfone as a base material has a thickness of 20 μm on the membrane surface, for example.
It has the following dense so-called skin layer and a relatively coarse porous structure that integrally supports this skin layer, and has a particle size of 0.
．． A porous membrane that has the ability to substantially block the permeation of particles of 0.1 μm or more, or a porous membrane that is almost homogeneous in the thickness direction of the membrane,
In addition, a porous membrane having a micropore diameter substantially in the range of 0.01 to 2 μm is preferably used. Generally, such porous membranes have a thickness of 20 j! / has a high pure water permeability rate higher than /rl/hour/atmospheric pressure. Such a porous membrane is also usually called a semipermeable membrane.

Further, in the present invention, the porous membrane made of the aromatic polysulfone as the base material may be formed on a reinforcing material such as a nonwoven fabric.

The shape of such an aromatic polysulfone porous membrane as a base material is not particularly limited in the present invention, but according to the present invention, when using a hollow fiber porous membrane, in particular An aromatic polysulfone hollow fiber semipermeable membrane with improved properties can be obtained. The hollow fiber porous membrane as a base material has an outer diameter of 500 to 4000 μm and an inner diameter of 2
00 to 3000 μm is preferable. Further, when a sheet-like aromatic polysulfone porous membrane formed on a nonwoven fabric is used, a composite semipermeable membrane with excellent flexibility can be obtained.

The aromatic polysulfone composite semipermeable membrane according to the present invention is produced by coating or impregnating a water-soluble polyvinyl alcohol-based polymer on the aromatic polysulfone porous membrane as described above, and then subjecting it to water insolubilization treatment to form an aromatic polysulfone porous membrane. It can be produced by substantially uniformly adhering the water-insolubilized polyvinyl alcohol polymer to the surface of the membrane and the inner surface of the micropores of this porous membrane.

The polyvinyl alcohol polymer used in the present invention has an average degree of polymerization of 200 to 3,500 and a degree of saponification of 85 to 100.
mol% polyvinyl alcohol, and monomer composition 20
It shall include a copolymer having vinyl monomer units of mol % or less. Examples of such vinyl monomers include ethylene, vinylpyrrolidone, acrylonitrile, and vinyl chloride.

As a method for water-insolubilizing such a polyvinyl alcohol polymer, in the present invention, a method of crosslinking the polyvinyl alcohol polymer molecules by an acetalization reaction with a polyhydric aldehyde is preferably adopted as the first method. be done.

According to this first method, the water-soluble polyvinyl alcohol polymer can be crosslinked at a high density, and therefore, for example, the permeation performance of a hollow fiber membrane made of aromatic polysulfone can be stabilized. However, the internal pressure strength can be significantly increased. Examples of the polyvalent aldehyde include, but are not limited to, polyvinyl alcohol dialdehyde, glutaraldehyde, glyoxal, and terephthalaldehyde.

In order to crosslink the polyvinyl alcohol polymer and make it water insolubilized by the acetalization reaction using the polyvalent aldehyde, for example, the aromatic polysulfone porous membrane as a base material is coated with polyvinyl alcohol at a concentration of 0.05 to 10% by weight. A porous membrane is impregnated with the above polymer by immersion in an aqueous solution of an alcoholic polymer, and after drying or without drying, the porous membrane is treated with the above-mentioned polyhydric aldehyde and a small amount of an acid catalyst. For example, the composite semipermeable membrane of the present invention can be obtained by immersing it in a solution containing hydrochloric acid or sulfuric acid.

Preferably, the aromatic polysulfone porous membrane treated with the polyvinyl alcohol polymer solution as described above is treated with a polyaldehyde concentration of 0.0001 to 5% by weight and an acid catalyst of 0.
．． It is immersed in a polyhydric aldehyde solution containing 1 to 30% by weight of OOO at a temperature of 0 to 80° C. for 1 minute to several tens of hours.

In this way, the water-insolubilized polyvinyl alcohol-based polymer can be almost uniformly adhered to the surface of the aromatic polysulfone porous membrane and the inner surfaces of the micropores. Thereafter, if necessary, the composite semipermeable membrane may be heat-treated by a method such as immersing it in hot water to adjust the micropore diameter of the resulting composite semipermeable membrane.

In the above treatment, preferable temperature conditions are 60°C or higher;
In particular, the temperature is 80° C. or higher, and the immersion is performed for 5 minutes or more, preferably 30 minutes or more.

In the aromatic polysulfone composite semipermeable membrane of the present invention thus obtained, the water-insolubilized polyvinyl alcohol polymer adhering to the surface of the porous membrane as a base material and the inner surface of the micropores is Although it is not necessary that the amount of adhesion be the same on the membrane surface and the inner surface of the micropores, it is necessary to maintain the porous membrane structure that is the base material and increase the permeation performance, especially the removal rate for solutes. preferable. Specifically, the amount of the water-insolubilized polyvinyl alcohol polymer deposited is usually preferably in the range of 0.1 to 20% by weight based on the polysulfone porous membrane, although it depends on the membrane thickness. When the amount of water-insolubilized polyvinyl alcohol polymer attached is too small, the permeation performance and pressure resistance are almost the same as those of the polysulfone porous membrane used as the original base material.On the other hand, when it is more than 20% by weight, This is because the permeation performance as a semipermeable membrane becomes inferior.

As mentioned above, a composite semipermeable membrane in which a polyvinyl alcohol-based polymer treated with water insolubilization with polyhydric aldehyde is adhered almost uniformly to the surface is made because the surface is made hydrophilic by the polyvinyl alcohol-based polymer. In addition, adsorption of solutes on the membrane surface is reduced, resulting in markedly improved permeation stability.Since the membrane is reinforced, it has excellent mechanical strength, especially in the case of hollow fiber composite semipermeable membranes. Moreover, its internal pressure resistance is significantly improved.

In the present invention, as a second method, an aromatic polysulfone porous membrane as a base material is immersed in an aqueous solution of a water-soluble polyvinyl alcohol polymer containing an inorganic alkaline compound, or the aqueous solution is applied to a porous membrane. After coating and drying, it is heated and in this way a composite semipermeable membrane according to the invention can be obtained.

More specifically, it contains 0.01 to 10% by weight of polyvinyl alcohol, preferably 0.2 to 2% by weight, and 0.01 to 5% by weight, preferably 0.1 to 1% by weight of an inorganic alkaline compound. The aromatic polysulfone porous membrane is immersed in an aqueous solution at a temperature of 0 to 80°C for 1 minute to several tens of hours, or the above aqueous solution is applied to the surface of the aromatic polysulfone porous membrane. After forming a thin layer of an aqueous solution of the polymer on the surface of the porous membrane,
By heating and drying at a temperature of 0°C, preferably 80 to 150°C, the water-insolubilized polyvinyl alcohol polymer can be almost uniformly adhered to the surface and inner surface of the micropores of the aromatic polysulfone porous membrane. can.

In this method, as the inorganic alkaline compound, alkali metal hydroxides, carbonates and hydrogen carbonates are preferably used, and specific examples include lithium hydroxide, potassium hydroxide, sodium hydroxide. , potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, etc., and potassium hydroxide and sodium hydroxide are particularly preferably used.

In the aromatic polysulfone composite semipermeable membrane obtained in this way, the water-insolubilized polyvinyl alcohol adhering to the surface of the porous membrane as the base material and the inner surface of the micropores is similar to that described above. The amount of polymer attached does not need to be the same on the membrane surface and the inner surface of the micropores, but it is necessary to maintain the porous membrane structure as a base material and increase the permeation performance, especially the removal rate for solutes. It is preferable that In the case of the second method, specifically, the amount of the water-insolubilized polyvinyl alcohol polymer attached is 0.01 to 20% by weight based on the polysulfone porous membrane, depending on the membrane thickness. A good range is preferred, particularly 0.1 to 5% by weight.

According to this second method, a water-soluble polyvinyl alcohol polymer can be made water-insoluble without using a crosslinking agent such as a polyaldehyde, and in particular, an aromatic polysulfone porous membrane can be made insoluble. A small amount of a polyvinyl alcohol-based polymer treated to eliminate the need for water can be almost uniformly adhered to the surface of the membrane, and in this way, a composite semipermeable membrane having excellent permeation stability and flexibility can be obtained. I can do it.

That is, the second method, in which a water-soluble polyvinyl alcohol polymer containing an inorganic alkaline compound is heated to make the polymer unnecessary for water, also improves the hydrophilicity of the aromatic polysulfone porous membrane and increases its permeability. Not only can the stability be improved, but also the removal rate for solutes can be increased. In particular, according to this second method, the resulting composite semipermeable membrane has flexibility, probably because the polyvinyl alcohol polymer is rendered water insolubilized without crosslinking. but,
When the amount of the water-insolubilized polyvinyl alcohol polymer attached is more than 20% by weight, it is not preferable because the permeation performance as a semipermeable membrane usually becomes poor.

(Effects of the Invention) According to the aromatic polysulfone composite semipermeable membrane of the present invention, as described above, the aromatic polysulfone porous membrane as a base material maintains its original porous membrane structure, and its surface and Since the water-insolubilized polyvinyl alcohol-based polymer is almost uniformly adhered to the inner surface of the micropores, the composite semipermeable membrane has micropores with a pore diameter of approximately 0.01 to 2 μm, and the membrane surface is made of polyvinyl alcohol-based polymer. Because it is made hydrophilic by the polymer, there is less adsorption of solutes on the membrane surface, resulting in significantly improved permeation stability, and the polyvinyl alcohol-based polymer is treated to make the inner surface of the micropores water insolubilized. is attached to reinforce the membrane, so the membrane has excellent mechanical strength, and in particular, in the case of a hollow fiber composite semipermeable membrane, its internal pressure resistance is significantly improved.

(Examples) The present invention will be described below with reference to Examples, but the present invention is not limited by these Examples. Moreover, in the following, parts shall mean parts by weight.

Example 1 Aromatic polysulfone having the repeating unit (III) (manufactured by Union Carbide [Polysulfone P-170]
15 parts of 0J and 5 parts of polyethylene glycol having an average molecular weight of 600 were dissolved in 80 parts of N-methyl-2-pyrrolidone. This solution is extruded into a hollow shape through an annular nozzle, and water is used as a coagulating liquid to coagulate from the inner and outer surfaces.
A hollow fiber porous membrane with an outer diameter of 1.0 fi was obtained.

When the cross section of this hollow fiber porous membrane was observed using a scanning electron microscope, it was found that it has a skin layer on the surface and a porous structure that becomes coarser toward the inside, with parts of it having a so-called finger-like structure. It was an anisotropic film with missing parts of the polymer. Further, the pure water permeation rate of this porous membrane was 6,001 t/d·hr·atm, and the removal rate for polyethylene glycol having an average molecular weight of 20,000 was 65%.

Next, as shown in Table 1, polyvinyl alcohol (PVA) with an average polymerization degree of 1700 and a saponification degree of 98.5 mol% was used.
The hollow fiber porous membrane was immersed in an aqueous solution of a predetermined concentration for 24 hours. After this, the hollow fiber membrane was dried at room temperature to prevent coalescence, and then immersed in an aqueous solution consisting of 96 parts of water, 1 part of sulfuric acid, and 3 parts of glutaraldehyde at a temperature of 30°C for 1 hour to make the polyvinyl alcohol insoluble in water. Processed.

When the hollow fiber composite semipermeable membrane thus obtained was observed using an electron microscope, it was found that the original porous structure was maintained as it was, and that water-insoluble polyvinyl alcohol was distributed almost uniformly on the membrane surface and the inner surface of the micropores. - It was confirmed that it was attached to.

The amount of adhesion of water-insolubilized polyvinyl alcohol on these composite semipermeable membranes, the removal rate for polyethylene glycol with an average molecular weight of 20,000, and the bursting strength were determined as follows.
Shown in the table.

Comparative Examples 1 and 2 The aromatic polysulfone hollow fiber porous membrane itself in Example 1 (Comparative Example 1) and this porous membrane were immersed in a 15% by weight polyvinyl alcohol aqueous solution and subjected to water insolubilization treatment with glutaraldehyde. Table 1 shows the removal rate and burst strength for polyethylene glycol having an average molecular weight of 20,000 for a composite semipermeable membrane (Comparative Example 2) in which the amount of water-insolubilized polyvinyl alcohol attached was 30% by weight.

Example 2 The aromatic polysulfone hollow fiber porous membrane obtained in Example 1 was immersed in an aqueous polyvinyl alcohol solution under various conditions as shown in Table 2 to make the polyvinyl alcohol insoluble in water. The conditions for immersing the porous membrane in the polyhydric aldehyde aqueous solution containing an acid catalyst were all kept constant at 60° C. for 130 minutes.

Table 2 shows the processing conditions and properties of the composite semipermeable membrane obtained.

Example 3 Aromatic polysulfone having the repeating unit (IV) (
17 parts of polyether sulfone (manufactured by IC1) and 5 parts of lithium chloride were dissolved in 78 parts of dimethylacetamide. Apply this solution to the inner surface of a polyester nonwoven pipe with an inner diameter of 12 mm.
After coating to a thickness of 50 μm, it was immersed in water to solidify.

In this way, the cross-section of the tubular porous membrane, which uses nonwoven fabric as a reinforcing material, was observed using a scanning electron microscope. It was a porous membrane. Further, the pure water permeation rate of this semipermeable membrane was 3001/M·hr·atmosphere, and the removal rate for polyethylene glycol having an average molecular weight of 20,000 was 75%.

The tubular porous membrane was immersed in a 2.0% by weight aqueous polyvinyl alcohol solution with an average degree of polymerization of 500 and a degree of saponification of 98.5 mol% at room temperature for 24 hours, then the surface was lightly washed with water and left to dry at room temperature for 1 day. Then, it was dried at 100°C for 2 hours. Thereafter, this tubular porous membrane was immersed in an aqueous solution consisting of 97 parts of water, 1 part of sulfuric acid, and 2 parts of glutaraldehyde at a temperature of 30° C. for 2 hours to insolubilize the polyvinyl alcohol in water.

When the tubular composite semipermeable membrane of the present invention thus obtained was observed using an electron microscope, it was found that the original porous structure was maintained as it was, and that water-insoluble polyvinyl alcohol was present on the membrane surface and the inner surface of the micropores. It was confirmed that the film was adhered almost uniformly.

The amount of adhesion was 3.2% by weight based on the original porous aromatic polysulfone membrane. In addition, the pure water permeability rate of this membrane is 260 I! , /rd・hour・atmosphere, average molecular weight 2000
The removal rate for polyethylene glycol No. 0 was 88%.

Using this composite semipermeable membrane according to the present invention and the original aromatic polysulfone porous membrane as a base material, a cationic electrodeposition paint with a nonvolatile content of 15% was continuously treated at a pressure of 2 kg/cJ.

As a result, as shown in FIG. 1, it was confirmed that when the composite semipermeable membrane according to the present invention was used, the water permeation rate remained high over time, and the permeation stability of the membrane was high. On the other hand, with the original porous membrane, the water permeation rate decreased rapidly after the start of treatment.

Example 4 Aromatic polysulfone having the repeating unit (III) (manufactured by Union Carbide [Polysulfone P-350]
0J 17 parts Dissolved in 83 parts of N-methyl-2-pyrrolidone. Spread this solution onto a polyester nonwoven fabric to a thickness of 150 μm.
After coating the membrane on the membrane, it was immersed in water at 10° C. to obtain an aromatic polysulfone porous membrane having a nonwoven fabric as a base material.

In the aromatic polysulfone porous membrane based on this nonwoven fabric, the polysulfone portion has a skin layer on the surface and a rougher porous structure toward the inside, as a result of observing the cross section with a scanning electron microscope. It was an anisotropic film. In addition, the pure water permeation rate of this porous membrane is 2801/rd
- hours and atmospheric pressure, and the removal rate for polyethylene glycol with an average molecular weight of 20,000 was 80%.

Next, as shown in Table 3, polyvinyl alcohol (PVA) with an average degree of polymerization of 2400 and a saponification degree of 88 mol% was used.
After applying a polyvinyl alcohol aqueous solution containing 3% by weight and a predetermined amount of a predetermined inorganic alkaline compound onto the aromatic polysulfone porous membrane to a thickness of about 10 μm, 1
The polyvinyl alcohol was dried by heating at a temperature of 20° C. for 5 minutes to make it insoluble in water, and then washed with water to obtain a composite semipermeable membrane according to the present invention.

When the composite semipermeable membrane thus obtained was observed using an electron microscope, it was found that the original porous structure was maintained as it was, and that water-insoluble polyvinyl alcohol was coated on the membrane surface and the inner surface of the micropores to a thickness of about 0. It was confirmed that it was almost uniformly adhered at a thickness of .1 μm, and that the amount of adhesion was 0.12% by weight based on the dry aromatic polysulfone porous membrane.

Table 3 shows the pure water permeation rate and the removal rate for polyethylene glycol having an average molecular weight of 20,000 in these composite semipermeable membranes.

24 ・Also, using the film 2 of the present invention shown in Table 3, the non-volatile content was 15
% of cationic electrodeposition paint was continuously treated at a pressure of 2 kg/cIil, as shown in Figure 2, when using the composite semipermeable membrane of the present invention, the water permeation rate was maintained high over time. , the permeation stability of the membrane is high.

Comparative Examples 3 and 4 The aromatic polysulfone porous membrane itself (Comparative Example 3) based on the polyester nonwoven fabric obtained in Example 4, and this porous membrane in a polyvinyl alcohol aqueous solution containing no inorganic alkali compound in Example 4 Except for soaking
Regarding the composite semipermeable membrane (Comparative Example 4) obtained in the same manner as in Example 4, the nonvolatile content was 15% in the same manner as in Example 4.
cationic electrodeposition paint was continuously treated at a pressure of 2 kg/aa.

As the results are shown in FIG. 2, when the membranes according to these comparative examples were used, the water permeation rate decreased significantly over time.

[Brief explanation of drawings]

Figure 1 shows the continuous treatment of cationic electrodeposition paint using the aromatic polysulfone composite semipermeable membrane according to the present invention (Example 3) and the aromatic polysulfone porous membrane as a membrane base material as a comparative example. It is a graph showing a change in water permeation rate over time. FIG. 2 shows that the aromatic polysulfone composite semipermeable membrane according to the present invention (Example 4) and the membrane as a comparative example were used, respectively.
It is a graph showing changes over time in water permeability and velocity when a cationic electrodeposition paint is continuously treated.

Claims (9)

[Claims] (1) An aromatic membrane characterized by having a water-insolubilized polyvinyl alcohol polymer adhered almost uniformly to the surface of a porous membrane made of aromatic polysulfone and the inner surface of the micropores of this porous membrane. Polysulfone composite semipermeable membrane. (2) The aromatic polysulfone composite semipermeable membrane according to claim 1, wherein the water insolubilization treatment of the polyvinyl alcohol polymer is an acetalization treatment with a polyhydric aldehyde. (3) Claim 1 or 2, characterized in that the amount of the water-insolubilized polyvinyl alcohol polymer attached is 20% by weight or less based on the porous membrane made of aromatic polysulfone. The aromatic polysulfone composite semipermeable membrane described. (4) The aromatic polysulfone composite semipermeable membrane according to claim 1, wherein the composite semipermeable membrane is a hollow fiber composite semipermeable membrane. (5) Claim 1, characterized in that a porous membrane made of aromatic polysulfone is formed on a nonwoven fabric.
The aromatic polysulfone composite semipermeable membrane described in . (6) After coating or impregnating a porous membrane made of aromatic polysulfone with an aqueous solution of a water-soluble polyvinyl alcohol-based polymer containing an inorganic alkaline compound, it is heated and dried to make the water-soluble polyvinyl alcohol-based polymer insolubilized in water. The aromatic polysulfone composite semi-conductor is characterized in that the above-mentioned water-insolubilized polyvinyl alcohol-based polymer is almost uniformly adhered to the surface of the above-mentioned porous membrane and the inner surface of the micropores of the above-mentioned porous membrane. Method for producing a permeable membrane. (7) An aromatic compound according to claim 6, characterized in that the amount of the water-insolubilized polyvinyl alcohol polymer attached is 20% by weight or less with respect to the porous membrane made of aromatic polysulfone. A method for producing a polysulfone composite semipermeable membrane. (8) The method for producing an aromatic polysulfone composite semipermeable membrane according to claim 6, wherein the composite semipermeable membrane is a hollow fiber composite semipermeable membrane. (9) Claim 6, characterized in that the porous membrane made of aromatic polysulfone is formed on a nonwoven fabric.
A method for producing an aromatic polysulfone composite semipermeable membrane as described in 2.