WO1993013853A1 - Process for producing semipermeable membrane - Google Patents

Abstract

A process for producing a semipermeable membrane widely used in the purification of foods, medicines, fermentation products and so forth and the treatment of industrial effluent, household effluent and so forth, which process provides a semipermeable membrane having significantly large performance as compared with the membranes produced by the conventional processes and can extend the upper limit of the content of acrylonitrile in an acrylonitrile copolymer for use as the membrane material up to 96.1 mol %. This process comprises producing a semipermeable membrane by phase conversion from a casting solution comprising a copolymer of acrylonitrile with a water-soluble nonelectrolyte monomer having an acrylonitrile content of 80-96.1 mol % as the membrane material, a water-miscible solvent therefor and a nonsolvent therefor which is miscible with both of water and the solvent, said nonsolvent being a monohydric C3 or C4 alcohol and/or a polyhydric C4 to C14 alcohol.

Description

 Description Method for producing semipermeable membrane Technical Field of the Invention

 The present invention relates to a method for producing a semipermeable membrane widely used for refining foods, pharmaceuticals, fermented products, and the like, and for treating industrial wastewater, domestic wastewater, and the like.

Description of related technology

 U.S. Pat. No. 3,950,257 discloses a semipermeable membrane (ultrafiltration membrane) using a copolymer of acrylonitrile and a non-electrolyte water-soluble monomer as a membrane material. ) Is a food, pharmaceutical, and fermentation product because the membrane has a good balance of membrane performance, and the membrane is relatively resistant to soiling and has the property of easily removing soiling by washing. It is widely used in the fields of refining, etc., and treating industrial and domestic wastewater. However, even with the above semipermeable membrane, the membrane performance, especially the permeation flux, has not yet sufficiently responded to the demands of users seeking continuous progress.

 The present invention has been made to meet such a user's demand, and has as its object to provide a method for producing a semipermeable membrane having higher membrane performance.

Disclosure of the invention

 In producing a semipermeable membrane by the phase conversion method, the present inventors have focused on the type of solvent and the non-solvent added to the solvent, among many factors that affect the membrane performance. A systematic review was performed. As a result, they found that the use of specific solvents and non-solvents could improve the permeation flux without reducing the solute rejection of the semipermeable membrane, and completed the present invention. It is.

That is, the present invention relates to a copolymer (a) of acrylonitrile and a non-electrolyte water-soluble monomer as a membrane material, wherein the acrylonitrile content is 8 0 mol% to 96.1 mol%, the copolymer (a), the solvent (b) of the copolymer (a) which is miscible with water, and the copolymer (a) A method for producing a semipermeable membrane by a phase conversion method from a solution (a distillate solution) comprising a non-solvent (c) of (a) which is miscible with both water and a solvent (b). In the above, the non-solvent (c) is a monovalent compound having 3 to 4 carbon atoms. An object of the present invention is to provide a method for producing an acrylonitrile-based semipermeable membrane characterized by using alcohol and / or a polyvalent alcohol having 4 to 14 carbon atoms. Even if it is a conventional membrane material, by applying the method of the present invention, the permeate flow rate can be reduced without decreasing the solute rejection rate of the membrane performance as compared with a conventionally obtained semipermeable membrane. A semipermeable membrane with a significantly larger bundle was obtained.

 In the present invention, the copolymer (a) having an acrylonitrile content of more than 90 mol% to 96.1 mol% can be used.

 As the solvent (b), it is preferable to use dimethyl sulfoxide and zo or dimethylformamide.

 The non-solvent (c) is selected from the group consisting of 1-butanol, 2-butanol, isobutyl alcohol and polyvalent alcohols having 7 to 14 carbon atoms. It is preferred to use at least one species selected from the group consisting of 1-butanol, 2-butanol, isobutyl alcohol and polyvalent alcohols having 7 to 11 carbon atoms. It is even more preferred to use one or more of the selected ones.

 Examples of the non-solvent (c) include 2-butanol, diethyl glycol, triethylene glycol, polyethylene glycol 200 and polyethylene. It is particularly preferable to use at least one member selected from the group consisting of renglycol, 300, and 2-butanol, triethylene glycol, and polyethylene glycol. It is most preferred to use one or more selected from the group consisting of call 200.

 As the non-solvent (c), 1-propanol, 2-propanol, 2-butanol, triethylene glycol, and polyethylene glycol It is also possible to use at least one member selected from the group consisting of

 Hereinafter, the configuration of the present invention will be described in detail.

 In the present invention, the membrane material is a copolymer (a) composed of acrylonitrile and a non-electrolyte water-soluble monomer, and has an acrylonitrile content of 8%. Use from 0 mol% to 96.1 mol%. The constituent monomers of this copolymer () are essentially acrylonitrile and a non-electrolyte water-soluble monomer. The acrylonitrile content is a value based on the total amount of the monomers (100 mol%).

Non-electrolyte water-soluble monomer means that the monomer is non-electrolyte and water-soluble, When the monomer is polymerized alone, the resulting polymer becomes a water-soluble monomer. Such materials include, for example, N-vinyl-12-oxazolidone, N-vinyl-12-pyrrolidone (hereinafter simply referred to as vinylpyrrolidone), and acrylic acid. , Acrylonitrile hologram, hydroxy methacrylate creature, hydroxy methacrylate create, etc.

 The acrylonitrile content of the copolymer (a), which is a membrane material, is 80 to 96.1 mol%. As the content of water-soluble monomer in the copolymer (a) increases, the permeation flux of the resulting semipermeable membrane increases, but the mechanical strength and heat resistance of the membrane tend to decrease. Therefore, the acrylonitrile content should be 80 mol% or more. On the other hand, if the acrylonitrile content exceeds 96.1 mol%, the membrane performance of the resulting semipermeable membrane, particularly the permeation flux, is not preferred. The acrylonitrile content is preferably increased within the above range, that is, more than 90 mol% to 96.1 mol%.

 Conventionally, in order to obtain an acrylonitrile-based semipermeable membrane having good membrane performance, the upper limit of the acrylonitrile content in the copolymer of the membrane material is 90 mol. % (See U.S. Pat. No. 3,950,257). However, according to the film forming method of the present invention, the upper limit of acrylonitrile content in the copolymer of the film material can be extended to 96.1 mol%. .

The method for producing the copolymer used in the present invention is not particularly limited, but generally, a monomer mixture as a raw material is mixed in a suitable solvent with an oil-soluble radical polymerization initiator (for example, benzoyl peroxide). The copolymerization is carried out in the presence of azobisisobutylonitrile. In the present invention, a commercially available acrylonitrile-based copolymer may be used as long as the acrylonitrile-based copolymer satisfies the limitation requirements of the present invention. . In the present invention, as the solvent (b) of the copolymer (a), a solvent which dissolves the copolymer (a) well and is miscible with water is used. The reason why water-miscible ones are used is that water or an aqueous solution, which is preferable from an economic and safety point of view, is used as a coagulating liquid during film formation and as a cleaning liquid for the cleaning tank. Examples of such a solvent (b) include dimethyl sulfoxide, dimethylinoformamide, dimethyl acetate, dimethylinoles norefone, 2-pyrrolidone, and N-methyl 2-pyrrolide. Dimethyl sulfo, etc. Preference is given to xide and di- or dimethylformamide.

 In the present invention, the non-solvent (c) of the copolymer (a) is one which does not dissolve the copolymer (a) but is miscible with both water and the solvent (b), and has one to three carbon atoms. Use at least one selected from a valence alcohol and a polyvalent alcohol having 4 to 14 carbon atoms. The use of a solvent that is miscible with both water and the solvent (b) is used to obtain a uniform cast solution, and as a coagulating solution during film formation and as a washing solution for the washing tank, and is economically safe. This is because it is desirable to use preferable water or aqueous solution. In addition, the use of monovalent alcohols having 3 to 4 carbon atoms and / or polyvalent alcohols having 4 to 14 carbon atoms makes it possible to use semi-permeable membranes obtained by conventional methods by using these. In comparison, a semipermeable membrane with almost the same or better solute rejection ratio and higher permeation flux is obtained.o-Monovalent alcohol having 3 to 4 carbon atoms For example, 1-prono. Knol, 2-propanol, 1-butanol, 2-butanol (sec-butyl alcohol), i-butyl alcohol and tert_butyl alcohol. Examples of polyvalent alcohols having 4 to 14 carbon atoms include diethyl glycol, triethylene glycol, dipropylene glycol, and polyether. Tile glycol 200 and Polyethylene glycol 300 and the like.

In the present invention, as the non-solvent (c), at least one selected from the group consisting of 1-butanol, 2-butanol, isobutyl alcohol and a polyvalent alcohol having 7 to 14 carbon atoms is used. Preferably, one or more selected from the group consisting of 1-butanol, ² -butanol, isobutyl alcohol and polyvalent alcohols having 7 to 11 carbon atoms are more preferably used. 2—Futanol, polyethylene glycol, triethylene glycol, polyethylene glycol 200 and polyethylene glycol It is particularly preferable to use at least one member selected from the group consisting of alcohol 300, and 2—butanol, triethylene glycol and polyethylene glycol 2 Most preferably, one or more members selected from the group consisting of 00 are selected.

In the present invention, as the non-solvent (c), 1-propanol, 2-propanol, 2-butanol, triethylene glycol and polyethylene glycol 20 are used. One or more members selected from the group consisting of 0 may be used. . In the present invention, an acrylonitrile-based semipermeable membrane is produced by a phase conversion method. An example of the film forming process (an example relating to the production of a flat film) is as follows.

 (1) Make a solution (cast solution) consisting of a polymer compound, a solvent, and a non-solvent (also called an additive).

 (2) Cast on a smooth base.

 (3) Evaporate the solvent for a short time from the cast liquid film.

 (4) Soak the entire membrane in the gelling solution.

 (5) Rinse the entire membrane with water.

 (6) Dry or heat treat.

 In the present invention, the conditions of each step are not particularly limited, but examples of the conditions are as follows. .

 (A) Composition of the cast solution

 The concentration of the copolymer (a), which is a membrane material, can be 10 to 35% by weight, but is preferably 16 to 27% by weight.

 (B) Liquid film thickness

 It is usually between 0.01 and 0.30 mm, preferably between 0.05 and 0.25 mm.

 The present invention includes not only a method for producing a flat membrane by a phase conversion method but also a method for producing a tubular membrane or a hollow fiber membrane by a phase conversion method.

 '' A copolymer of acrylonitrile and a non-electrolyte water-soluble monomer having an acrylonitrile content of 80 to 96.1% was used as the membrane material. Then, when a semipermeable membrane (ultrafiltration membrane) is produced by the method of the present invention, it has higher membrane performance than a semipermeable membrane obtained by a conventional method, that is, solute rejection. A semipermeable membrane is obtained in which one or both of the permeability and the permeation flux are significantly larger. Further, when the present invention is applied, the upper limit of the acrylonitrile content in the copolymer, which has been 90 mol% in the past, is reduced in both the solute rejection rate and the permeation flux. Without this, it can be expanded to 96.1 mol%.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. It is not limited to.

 Examples 1 to 3, Reference Examples 1 to 7

 The difference between the embodiment and the reference example lies in the type of non-solvent (additive).

 First, according to the method disclosed in U.S. Pat. No. 3,950,257, acrylic D nitrile and vinylpyrrolidone are copolymerized to obtain an acrylonitrile content. 9 2.3 mol%, vinyl alcohol content of 7.7 mol%, reduced viscosity 2.96 d1 / g [1 gd1 dimethylformamide (DMF) solution Measurement] was obtained. The polymerization conditions of this copolymer are as follows.

(Used container) 2 1 volume separable glass

 (Preparation conditions)

 Acrylonitrile (all initially prepared) 1 2 2.0 S

 Vinyl pyrrolidone (initial charge) 5.2 g

 Hazobis isobutyronitrile 0.6 9 g

 No Clean 2 0 0.0 g

 Vinyl pyrrolidone (additional charge, 8 g

 Preparation conditions: 2 g / '

 Mouth i † 1 3 3 9. 6 9 g

 (Polymerization temperature) at 65.0

 (Polymerization atmosphere) Under nitrogen gas

 (Pressure during polymerization) Normal pressure

 (Polymerization time) 6.0 hours

 (Copolymer yield) 1 17.3 g (Yield: 84.4%)

(Acrylonitrile content of Cobo> / mer) 92.3 mol% (by CHN analysis) Then, dimethyl sulfoxide (DMS0) as a solvent and as an additive The copolymer was dissolved in a mixed solution of the above with various non-solvents (copolymer concentration: 18% by weight of the total amount) to obtain a cast solution. This cast solution is cast on a polyester nonwoven fabric to a thickness of about 0.2 mm, and after about 3 seconds, immersed in water at a temperature of about 2'5 ° C. 瀆 to form a film. After leaving sufficient wash residual solvent in the resulting film, cut out the effective membrane area 2 5 test piece oval shaped cm ² from the membrane, mounted it circulating tester flux of pure water (abbreviated as PWP, ^{unit: ΐ Ζιη 2 · h · kgf} · cm "2) in the effective pressure lkgf / cm ^2, or, to substantially and bovine serum Arve Mi emissions (BSA concentration l OO ppm> buffer solution The solute rejection rate (abbreviated as R ej, unit:%) and permeation flux (abbreviated as PR, unit: 1 / 'm ² · h · kg ί · cm- ² ) are calculated as follows: It was set at

 The results are shown in Table 1.

Comparative Examples 1-2

 As a comparative example, we selected the one that gave the highest membrane performance among the conventional membrane formulations (cast solution formulations). That is, a copolymer consisting of vinyl virion and acrylonitrile having an acrylonitrile content of 89.4 mol% was converted to dimethylformamide (III. ) In a mixed solution of MF) and 1,4-dioxane, the copolymer was dissolved to a concentration of 17% by weight (Comparative Example 1) or 20% by weight (Comparative Example 2). Film formation was performed in the same manner as in Examples 1 and 2, and film performance was evaluated.

 The results are shown in Table 1. In addition, in order to make it easy to compare the superiority of various additives, the results of permeation flux (permeation flux) of the membrane performance of the semi-permeable membranes of Examples and Reference Examples were compared with those of the semi-permeable membrane of Comparative Example. Table 2 shows the conversion to the ratio to the measurement result (permeation flux).

According to the results shown in Tables 1 and 2, there is almost no decrease in the solute rejection and the improvement in permeation flux is significant when the nonsolvent (additive) is 1-propanol or 2- It turns out that this was the case when using butanol.

Table 1 Effects of various additives (non-solvents)

* The total of solvent, additive (non-solvent) and Kobolimer is 100% by weight. Table 2 Effects of various additives (solvent: DMS 0)

P WP ratio PR ratio (BSA) Additive type vs. comparative example 1 vs. comparative example 2 vs. comparative example 1

 0/0

 (%) Example 1 1-F \ ° N ° 1 27 1 48 1 0 9 夹 Example 2 2 -Phthano 1 d 9 1 52 1 1 3 Example 3 Diethylene glycol 1 0 1 1 42 1 805 Reference example 1 Ethylene glycol 7 9 1 33 9 7 Reference example 2 Acetone 44 78 5 7 Reference example 3 N-lactic acid 44 87 6 3 Reference example 4 Propionic acid 80 1 34 9 8 Reference example 5 Urea 20% aqueous solution 86 1 3 8 1 0 1 Reference example 6 Sodium sodium dodecyl sulfate 7 9 1 26 9 2

2% aqueous solution Reference example 7 Lithium chloride 20% aqueous solution 74 1 1 2 8 2

Example 4 to: L 0, Reference Examples 8 to 13

 Except that the copolymer concentration in the casting liquid was changed from 18% by weight to 16% by weight, a film was formed in the same manner as in Examples 1 to 3, and the film performance was evaluated.

The results are shown in Table 3. In order to make it easy to compare the superiority of various additives, the measurement results (permeation flux) of the membrane performance of the semi-permeable membrane of the example and the reference example were compared with the measurement results of the membrane performance of the semi-permeable membrane of the comparative example. (Permeate flux), and the results shown in Table 3 and Table 4 in Table _4c show the degree of improvement in permeate flux when the BSA buffer solution was permeated (Comparative Example (For semipermeable membranes) is the largest among semipermeable membranes formed using 1-propanol, 2-butanol, and triethylene glycol as non-solvents (additives). 2—Semi-permeable membrane formed using propanol, diethyl glycol, diethyl glycol monomethyl ether, and triethylene glycol methyl ether, followed by a large membrane You can see that. Looking at the solute removal rate for the latter group, the semipermeable membrane formed using 2-propanol has a solute removal rate of 80 (Comparative Example 1) or 88% (Comparative Example 2). ) To 96%, but film formation using ethylene glycol, diethyl glycol monomethyl ether and triethylene glycol methyl ether respectively. The resulting semi-permeable membranes have dropped to 74%, 66% and 74%, respectively. Therefore, considering the solute exclusion rate, 1-prono is used as the non-solvent. The use of knol, 2-butanol, triethylene glycol and 2-propanol is significantly better.

Table 3 Effects of various additives (non-solvents)

* The total of solvent, additives (non-solvent) and copolymer is 100% by weight. Table 4 Effects of various additives (solvent: DMS 0)

P WP ratio PR ratio (BSA) Additive type

 Comparative Example 1 Comparative Example 2 Comparative Example 1

(%) (%) (%) Example 4 1—Pro No. 208 1 85 1 3 5 Example 5 1 One Pro No. 223 1 9 3 1 1 Example 6 1 One Pro No. 243 2 1 2 1 5 5 Example 7 2-Pronolone 182 1 83 1 3 3 Example 8 2-butanol 229 1 9 7 1 44 Example 9 Triethylene glycol 1 55 1 97 1 4 Example 10 0 Diethylene glycol 19 3 1 82 1 3 3 Reference Example 8 Tetra Hydro Full Free 1 3 9 1 55 1 1 3

Reference Example 9 Diacetone Reference 1 72 1 74 I 27 Reference Example 1 0 2—Pyrrolidone 145 1 67 1 2 3 Reference Example 1 1 Acetone 46 7 9 5 8 Reference Example 1 2 Diethylene glycol 1 53 1 8 1 1 3 3 Methyl athesole Reference example 13 Triethylene glycol 9 6 1 40 1 0 2 Dimethinoleate Examples 11 to 14, Reference Examples 14 to 17

 Films were formed in the same manner as in Examples 4 to 10 except that the solvent was changed from DMSO to DMF, and the film performance was evaluated.

 Table 5 shows the results. In order to make it easy to compare the superiority of various additives, the measurement results (permeation flux) of the membrane performance of the semi-permeable membrane of the example and the reference example were compared with the measurement results of the membrane performance of the semi-permeable membrane of the comparative example. Table 6 shows the conversion to the permeation flux.

 According to the results shown in Tables 5 and 6, the degree of improvement of the permeation flux when permeating the BSA buffer solution (as compared to the semipermeable membrane of the comparative example) was determined to be a non-solvent (additive). The largest semipermeable membrane formed using 2—butanol or polyethylene glycol 200, the most common diethylene glycol, monoethylene glycol monomono It can be seen that the semipermeable membrane formed using methyl ether, polyethylene glycol 300 and polyethylene glycol 600 is the second largest.

DMF is one of the solvents for this copolymer (acrylonitrile-based copolymer) that, together with DMSO, can form a membrane with the highest permeation flux. This is clear from the results shown in Tables 5 and 6. When a semipermeable membrane was produced by the method of the present invention using DMF as a solvent, the solute rejection was generally somewhat lower than in Comparative Example 1. Among the above-mentioned additives which give a semipermeable membrane having a high rate of improvement in permeation flux compared to Comparative Example 1, among the above-mentioned additives, diethyl glycol monomethyl, polyethylene and polyethylene The solute exclusion rate was significantly reduced in the semipermeable membranes manufactured using Nglycol 300 and polyethylene glycol 600. Therefore, taking into account the solute rejection, when the solvent is DMF, it can be said that 2-butanol and polyethylene glycol are the best additives. '

Table 5 Effects of various additives (solvent: DMF)

* The sum of solvent, additives (non-solvent) and copolymer is 100% by weight,

Table 6 Effects of various additives (solvent: DMF)

Additive type PWP ratio PR ratio (BSA) vs. Comparative example 1 vs. Comparative example 1 Example 1 2 — Butanol 2 15% 49% Example 1 2 Polyethylene glycol 2 7 7 1 4 9

 2 0 0 Example 1 3 Diethylene glycol 1 9 3 3 3 Example 1 4 Polyethylene glycol 1 9 9 3 3

 3 0 0 Reference example 1 4 Diethylene glycol Remo 1 5 3 1 3 3 No methyl ether

Reference Example 1 5 Triethylene Ring 9 6 0 2 Dimethyl ether Reference Example 1 6 Polyethylene Ring 2 3 6 1 2 5

6 0 0 Reference Example 1 Lactic acid 9 1 9 6 Examples 15 to 17

 The copolymers consist of acrylonitrile and vinyl vinyl acetate, with an acrylonitrile content of 85.7 mol%, 92.3 mol% or 98.3 mol%. 6.1 mol% of copolymer was used, and in each case the copolymer concentration was 17% by weight, the additive was 11 propanol, and the concentration was 12% by weight. Were formed in the same manner as in Examples 1 to 10, and the film performance was evaluated. Table 7 shows the results.

The results in Table 7 show that as the acrylonitrile content increases, the solute rejection of the resulting semipermeable membrane increases and the permeation flux tends to decrease. However, the amount of acrylonitrile content of the copolymer, which can be used in the conventional film-forming process, exceeds the upper limit of 90 mol%, which is 96.1 mol%. However, in the semipermeable membrane obtained by the method of the present invention, 122% of that of the semipermeable membrane of the comparative example was used as the permeation flux of the BSA (100 ppm) buffer solution. Indicated. As described above, in consideration of a large increase in the solute rejection rate of the semipermeable membrane obtained by the method of the present invention, even when the rate of improvement of the permeation flux is small, the semipermeable membrane obtained by the method of the present invention is small. The effect of improving the membrane performance of the permeable membrane is obvious.

Table 7 Effect of acrylonitrile content

Example 18 to 20

 ^ Instead of using 12% by weight of 1-propanol as an additive, a mixture of 2-butanol and polyethylene glycol 200 in a 2: 3 (weight ratio) mixture is used. A film was formed in the same manner as in Examples 15 to 17 except that the film was used so as to become the weight%, and the film performance was evaluated. Table 8 shows the results.

From Table 8, it can be seen that the change in film performance with an increase in the content of acrylonitrile in Examples 18 to 20 is smaller than that in Examples 15 to 17. However, even when a copolymer having an acrylonitrile content of 96.1% was used, the resulting semi-permeable membrane exhibited a permeation flux of a BSA (100 ppm) buffer solution. As a result, 126% of that of the semipermeable membrane of the comparative example was shown. As described above, in consideration of a large increase in the solute rejection of the semipermeable membrane obtained by the method of the present invention, even when the rate of improvement of the permeation flux is small, the semipermeable membrane obtained by the method of the present invention can be used. The effect of improving the membrane performance of the membrane is evident. Table 8 Effect of Acrylonitrile Content

Example 21 and Comparative Example 3

 A polymer solution (cast solution) having the same composition as that used in Example 1 was continuously applied to the inner surface of a polyester nonwoven fabric cylinder having an inner diameter of 14.6 mm to a thickness of about 0.15 mm. After coating, it was immersed in water at about 25 ° C to form a continuously formed tubular membrane.c From this tubular membrane, a flat membrane with the same dimensions and the same shape as in Example 1 was cut out. The film was mounted on the same device as in Example 1, and the membrane performance was evaluated. As a comparative example, a film was formed in the same manner as in Example 21 except that a polymer solution (cast liquid) having the same composition as that used in Comparative Example 1 was used. The film performance was evaluated. Table 9 shows the results.

Also in the case of the tubular membrane, similarly to the flat membrane, the semipermeable membrane obtained by the method of the present invention showed significantly better performance than the semipermeable membrane obtained by the conventional method. Table 9 Performance of tubular membrane

Example 22

 Acrylonitrile content 92.3 Using a copolymer consisting of acrylonitrile and butylpyrrolidone with a monore% of concentration, the concentration of the copolymer is 17% by weight. %, 2-butanol (additive) Concentration: 12% by weight, DMSO (solvent): 71% by weight, except that a cast solution was prepared and used in the same manner as in Example 21. Then, a tubular membrane was made, and the membrane performance was evaluated. Table 10 shows the results.

As in Example 21, the semipermeable membrane obtained by the method of the present invention showed significantly better performance than the semipermeable membrane obtained by the conventional formulation. Table 10 Performance of tubular membrane

Example 23

 Using a copolymer consisting of acrylonitrile and vinylpyrrolidone having an acrylonitrile content of 89.4 mol%, a copolymer concentration of 16 wt. A casting solution having a concentration of 2000 (additive) concentration of 16% by weight and a DMS 0 (solvent) concentration of 68% by weight was prepared.

 The cast liquid is continuously extruded from a cylindrical orifice (between the inner tube and the outer tube) of a double-tube nozzle into a cylindrical shape, and water at approximately 40 ° C is discharged. The hollow fiber membrane having an inner diameter of 0.52 mm and an outer diameter of 0.78 mm was spun. During the extrusion of the casting liquid, water was continuously extruded from the central orifice as the core liquid. The obtained hollow fiber membrane is cut to a length of 20 cm to form a sample, and an injection needle connected to a pipe for circulating a test solution is inserted into both ends thereof, and the sample and the injection needle are rapidly cured. The membrane performance was measured by the internal pressure method after sealing with a flexible epoxy adhesive. Table 11 shows the results.

As is clear from Table 11, according to the method of the present invention, a membrane having excellent performance was able to be obtained even in the case of a hollow fiber membrane. Table 11 Performance of hollow fiber membrane

P W P BSA (lOQppra) buffer solution Additive

 (1 / m hkgf cm) R e j P R

(%) (l / m ² hkgfcm ^1-2 ) Example 2 3 Polycarbonate 4 2 0 9 5 1 9 8

 Call 2 0 0

Claims

The scope of the claims 1. Copolymer of acrylonitrile and a non-electrolyte water-soluble monomer as the membrane material (a), which has an acrylonitrile content of 80%. Mole% to 96.1 mole%, the copolymer (a), the solvent (b) of the copolymer (a) which is miscible with water, and the copolymer (a). A semipermeable membrane is produced by a phase conversion method from a solution (cast liquid) comprising a non-solvent (c) of (a) which is miscible with both water and a solvent (b). The method according to claim 1, wherein the non-solvent (c) is a monovalent alcohol having 3 to 4 carbon atoms and / or a polyvalent alcohol having 4 14 carbon atoms. A method for producing a tolyl-based semipermeable membrane.  2. The semipermeable membrane according to claim 1, wherein the acrylonitrile content (a) is more than 90 mol% to 96.1 mol%. Manufacturing method.  3. The method for producing a semipermeable membrane according to claim 1, wherein the solvent (b) is dimethyl sulfoxide and Z or dimethylformamide.  4. The solvent (c), which is at least one selected from the group consisting of 1-butanol, 2-butanol, isobutyl alcohol and polyvalent alcohol having 7 14 carbon atoms. 3. The method for producing a semipermeable membrane according to item 1.  5. The non-solvent (c) is at least one selected from the group consisting of 1-butanol, 2-butanol / isobutyl alcohol, and polyvalent alcohols having 71 carbon atoms. The method for producing a semipermeable membrane according to claim 1, wherein  6. The non-solvent (c) contains 2-butanol, diethyl glycol, triethylene glycol, polyethylene glycol 200 and polybutane. Re-ethylene glycol 3 2. The method for producing a semipermeable membrane according to claim 1, wherein the method is one or more selected from the group consisting of 00. 7. The method according to claim 1, wherein the non-solvent (c) is at least one selected from the group consisting of 2-butanol, triethylene glycol, and polyethylene glycol 200. A method for manufacturing a permeable membrane. 8-The non-solvent (c) changes from a group consisting of 1-pro ⁰ -nor, 2-propanol, 2-butanol, triethylene glycol and polyethylene glycol 200 3. The method for producing a semipermeable membrane according to claim 1 or 2, wherein the method is one or more types. . One-