JP2525038B2 - Selective permeable membrane and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a permselective membrane and a method for producing the same, and particularly to a permselective membrane having a separation ability suitable as a separation membrane by a pervaporation method of a liquid mixture. Is provided.

(Problems to be Solved by the Prior Art and Invention) In a pervaporation method (permeation method) which is effective as a separation technology for a mixture of organic liquids or a solution of an organic compound, especially a compound having a boiling point close to the azeotropic mixture, A separation membrane having good separation ability and industrially excellent durability is required. That is, in such a pervaporation method, an organic liquid mixture is supplied to one side through a separation membrane, and the other side is depressurized or vacuumed,
Since a specific liquid component is vaporized and taken out, a separation membrane having separation ability as well as chemical resistance, heat resistance, mechanical strength, etc. is required.

Conventionally, as a material of the separation membrane, polymers such as cellulose, polyvinyl, polyamide, polyester, polysulfone, polycarbonate, and polyimide-based polymers have been proposed, although they differ depending on the use. Among them, polymers generally known as engineering plastics have good heat resistance, chemical resistance, etc., but they are still insufficient as a material for a separation membrane showing sufficient separation ability in the pervaporation method as described above.

[Means for solving the problem]

As a result of earnest studies in view of the above problems, the present inventors have selected an aromatic condensation polymer having a quaternary ammonium salt group as a side chain of a vinyl polymer, particularly in a pervaporation method. The present invention has been completed based on the finding that it is extremely effective as a material for a separation membrane having good permeability and mechanical strength.

That is, the present invention has a structure in which an aromatic condensation polymer and a vinyl polymer are bonded by a carbon-nitrogen bond through a quaternary ammonium base, and has an anion exchange capacity of 0.1-.
It is a selectively permeable membrane characterized by being 3.0 meq / g (dry membrane).

Here, the carbon-nitrogen bond means that a carbon atom and a nitrogen atom are bound to each other in the form of a covalent bond and / or a coordinate bond.

As the aromatic condensation polymer that can be used in the present invention, a known polymer having an aromatic hydrocarbon group in the main chain and obtained by condensation polymerization can be used without any limitation. For example, a polymer in which aromatic hydrocarbon groups are bound to each other by an oxy group, a thio group, a carbonyl group, a sulfonyl group, an alkylidene group, an alkylene group, an acid amide group, an acid imide group and the like can be mentioned.

Specific examples of the aromatic condensation polymer that can be preferably used in the present invention include polyphenylene, polyphenylene oxide, polysulfone, polyether sulfone,
Examples thereof include polyphenylene sulfide, polyether ketone, polyimide and polyether imide. When the permselective membrane of the present invention is used as a separation membrane in the paper permeation method, the following formula (I) is used because of the ease of molding into a membrane and the haloalkylation described later. (However, A _r1 and -A _r2 represent a divalent aromatic hydrocarbon group) or the following formula (II) A polyetherimide or polysulfone having a repeating unit represented by is preferably used. In particular, in the present invention, the following formula (III) A polyetherimide having a repeating unit represented by is preferable. Generally, the average molecular weight is preferably 20,000 or more from the viewpoint of the mechanical strength of the obtained selectively permeable membrane.

A haloalkyl group is introduced into the aromatic condensation polymer described above through a vinyl polymer described below through a quaternary ammonium salt group so as to be bonded by a carbon-nitrogen bond. As the haloalkyl group, a chloromethyl group, a bromomethyl group, an iodomethyl group, a chloroethyl group or the like is generally used. As a method for introducing a haloalkyl group into the aromatic condensation polymer, a known method is used. For example, a halomethyl ether such as chloromethyl ether is used as the haloalkylating agent, and a Friedel-Crafts type catalyst such as SnCl ₄ , TiCl ₄ or AlCl ₃ is used as the catalyst, and aromatic haloalkylation is carried out uniformly. As the solubilizer or swelling agent for the condensation polymer, for example, halogenated hydrocarbon such as 1,2-dichloroethane or tetrachloroethane is preferably used. The degree of haloalkylation in such an aromatic condensation polymer is generally preferably 3 to 12% by weight, as expressed by the halogen content measured by the More method. The number of haloalkyl groups introduced per repeating unit of the aromatic condensation polymer calculated from the above halogen content is generally 0.5 to 2.2. Moreover, it can be confirmed from the measurement of ¹ H-nuclear magnetic resonance spectrum that the haloalkyl group is introduced into the aromatic ring of the aromatic condensation polymer.

On the other hand, the vinyl polymer has in its side chain at least one nitrogen-containing group selected from the group consisting of primary amino group, secondary amino group and tertiary amino group. These nitrogen-containing groups are necessary for forming a quaternary ammonium salt group by the reaction with the haloalkyl group contained in the aromatic condensation polymer described above.

The aromatic condensation polymer and the vinyl polymer are bonded via a quaternary ammonium salt group. The quaternary ammonium base is formed by the reaction between the haloalkyl group and the nitrogen-containing group possessed by each of the above-mentioned polymers and, if necessary, the quaternization reaction. The quaternary ammonium base includes trialkylammonium base, triarylammonium base, dialkylarylammonium base, diarylalkylammonium base, pyridinium base, pyrrolium base, piperidinium base, quinolinium base, indolium base, imidazolium base, pyrazinium base, and the like. Can be mentioned.

The amount of the quaternary ammonium base contained in the selectively permeable membrane of the present invention can be determined by measuring the ion exchange capacity, and is generally in the range of 0.1 to 3.0 meq / g- (dry membrane). 0.3 to 2.0 meq / g-
It is preferably in the range of (dry film).

Here, the ion exchange capacity, as described in Kyoritsu Shuppan Co., Ltd., published on November 10, 1963, "Ion Exchange Membrane", first edition, page 122, is equivalent to the equivalent of the exchange group per 1 g of dry resin. It shall be expressed as a number.

Further, since the selectively permeable membrane of the present invention contains a methylene chain based on a vinyl polymer, a peak based on the methylene chain can be confirmed by measurement by ¹³ C-nuclear magnetic resonance spectrum.

The method for producing the selectively permeable membrane of the present invention is not particularly limited, but the following methods (a) to (c) are preferably adopted.

(A) Aromatic condensation polymer having a haloalkyl group, and a vinyl monomer having at least one nitrogen-containing group selected from the group consisting of primary amino group, secondary amino group and tertiary amino group. A method in which the vinyl monomer is polymerized, and a quaternization reaction is carried out if necessary.

(B) Aromatic condensation polymer having a haloalkyl group, and a vinyl monomer having at least one nitrogen-containing group selected from the group consisting of primary amino group, secondary amino group and tertiary amino group. And a quaternization reaction, if necessary, and then polymerizing the vinyl monomer.

(C) An aromatic condensation polymer having a haloalkyl group, and a vinyl polymer having at least one nitrogen-containing group selected from the group consisting of a primary amino group, a secondary amino group and a tertiary amino group. And a quaternization reaction if necessary.

 These methods will be described below in order.

First, in the above method (a), as the aromatic condensation polymer having a haloalkyl group, the aforementioned aromatic condensation polymer having a haloalkyl group introduced therein is used. On the other hand, as the vinyl monomer having at least one nitrogen-containing group selected from the group consisting of primary amino group, secondary amino group and tertiary amino group, the above-mentioned nitrogen-containing group and vinyl group can be used. The vinyl monomer contained in one molecule is adopted without any limitation. For example, N-vinyldimethylamine, N-vinyldiethylamine, N-vinyldiphenylamine, vinylpyridine,
Examples thereof include N-vinylpyrrole, N-vinylindole, vinylquinoline, vinylpiperidine, vinylpyrazine, N-vinylimidazole, vinylbenzolamine, N, N-dimethylvinylbenzylamine and methacryloylaminopropyldimethylamine. Among these, vinyl pyridine and N, N-dimethylvinylbenzylamine are particularly preferably used.

An aromatic condensation polymer having a haloalkyl group, and a vinyl monomer having at least one nitrogen-containing group selected from the group consisting of primary amino groups, secondary amino groups and tertiary amino groups. For the contact, generally, a method in which the above vinyl monomer is dissolved or diluted with a suitable solvent to be in a liquid state, and this is brought into contact with an aromatic condensation polymer having a haloalkyl group is preferably adopted. For example, a method of immersing the aromatic condensation polymer in the vinyl monomer or a method of coating or spraying the vinyl monomer on the aromatic condensation polymer can be mentioned.

In addition to the above vinyl monomers, the use of a polyvinyl compound having two or more vinyl groups in the molecule is preferable because the mechanical strength of the resulting selectively permeable membrane is improved. As the polyvinyl compound, divinylbenzene,
Known compounds such as bisvinylphenylethane and bisvinylphenyl ether are used. Further, the amount of the polyvinyl compound used is preferably in the range of 1 to 30% by weight based on the ratio of the polyvinyl compound to the mixture with the vinyl monomer.

A polymerization initiator is generally used for the polymerization of vinyl monomers. As the polymerization initiator, known ones are used without any limitation. For example, benzoyl peroxide,
Organic peroxides such as lauroyl peroxide, cumene hydroperoxide and t-butyl hydroperoxide; azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile; benzoin, benzoin methyl ether, acetoin benzophenone, camphorquinone , Photo-initiators such as acetophenone and α-hydroxyacetophenone can be used. Further, ammonium persulfate-sodium sulfite, hydrogen peroxide-ferrous salt,
A redox type polymerization initiator in which an oxidizing agent such as benzoyl peroxide-dimethylaniline and a reducing agent are combined can also be used.

These polymerization initiators can be used usually in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the vinyl monomer. These polymerization initiators can be used by mixing with the above vinyl monomer, or can be dissolved in a suitable solvent to form a solution, and the aromatic condensation system polymer after contacting with the above vinyl monomer can be used. It can also be used by contacting with a united body.

For the polymerization of the vinyl monomer, a method suitable for each polymerization initiator is adopted. For example, when an organic peroxide or an azo compound is used, the temperature can be raised to about 40 to 80 ° C., and when a photopolymerization initiator is used, the polymerization can be performed by irradiation with ultraviolet rays. .

The vinyl monomer can also be polymerized by radiation without using the above-mentioned polymerization initiator.

When vinyl pyridine is used among the vinyl monomers described above, the aromatic condensation system aggregate and the vinyl monomer are brought into contact with each other at a temperature of 10 to 80 ° C., or the aromatic condensation system polymer and vinyl are used. After contact with the monomer, the temperature is raised to 10 to 80 ° C. to form a quaternary ammonium base, and the vinyl monomer is polymerized without using a polymerization initiator. The time required for the polymerization is usually several minutes to 100 hours.

In this way, the above-mentioned vinyl monomer is polymerized.

When the nitrogen-containing group contained in the vinyl monomer is a tertiary amino group due to the contact between the aromatic condensation polymer and the vinyl monomer, the reaction with the haloalkyl group contained in the aromatic condensation polymer is performed. A quaternary ammonium base is produced. However, when the nitrogen-containing base of the vinyl monomer is the primary amino group or the secondary amino group, the secondary amino group or the tertiary amino group is obtained by the reaction with the haloalkyl group. In this case, a quaternization reaction is further performed using a quaternization agent to convert these secondary amino groups or tertiary amino groups into quaternary ammonium bases. Known compounds such as methyl iodide, 1,2-dibromoethane, and benzol chloride are used as the quaternizing agent, and the quaternization reaction is performed under heating in an alcohol solvent at 10 to 80 ° C. Well-known conditions such as that are adopted.

When the nitrogen-containing group of the vinyl monomer is a tertiary amino group, a quaternary ammonium salt group can be produced by contacting the aromatic condensation polymer with the vinyl monomer. In order to more completely produce the quaternary ammonium base, it is preferable to carry out the quaternization reaction by heating at a temperature of 30 to 80 ° C. for several minutes to several hours.

Next, the manufacturing method (b) of the above-mentioned permselective membrane of the present invention will be described. This method is described in (a) above.
In this method, the order of the vinyl monomer polymerization and the quaternization reaction is reversed. That is, after bringing the aromatic condensation polymer and the vinyl monomer into contact with each other, a quaternization reaction is carried out if necessary, and then the vinyl monomer is polymerized. The respective processing methods are the same as the above-mentioned method (a).

Finally, the method (c) for manufacturing the above-mentioned permselective membrane of the present invention will be described. In this method, first, the vinyl monomer is polymerized. Then, the obtained vinyl polymer is dissolved in a suitable solvent, for example, methanol, isopropanol, nitromethane, acetone, hexane, methyl ethyl ketone, etc. to prepare a vinyl polymer solution, and the vinyl polymer solution and the aromatic condensation polymer are prepared. Contact is made. As the contacting method, the method of contacting the vinyl monomer and the aromatic condensation polymer in the method (a) is employed as it is. Then, if necessary, the quaternization reaction is carried out by the same method as described in the method (a).

When the permselective membrane of the present invention is produced by the above method, it is formed into an appropriate shape depending on the application. In any of the above methods, it is preferable to mold the aromatic condensation polymer having a haloalkyl group after introducing the haloalkyl group into the aromatic condensation polymer because molding is easy. As the molding method, any known method can be adopted without any limitation, but usually, an aromatic condensation polymer having a haloalkyl group dissolved in an organic solvent is solidified in a coagulating liquid to form a film-like material. The method is preferred. The shape of the membranous material may be any shape such as a flat membrane and a hollow fiber membrane.

(Effect) The permselective membrane provided in the present invention exhibits excellent selectivity and high permeation amount when used as a separation membrane in the pervaporation method. This effect is particularly remarkable when the alcoholic water system is separated.
Further, the selective permeable membrane of the present invention has a structure in which the aromatic condensation polymer and the vinyl polymer are entangled with each other, so that the selective permeable membrane has high mechanical strength. In particular, when a polyvinyl compound is used at the time of producing a vinyl polymer, the formation of a crosslinked structure makes it possible to obtain a selectively permeable membrane having further excellent mechanical strength.

Therefore, the permselective membrane obtained in the present invention is suitable for separation, concentration and purification of a mixture of organic liquids or a mixture containing a non-aqueous liquid such as a solution of organic compounds, and has wide fields such as electronics, biochemistry, pharmaceuticals and foods. It can be used in.

Example 1 Repeating unit represented by the following formula Aromatic ether imide polymer containing (trade name: Ultem 1000, manufactured by General Electric: molecular weight 40,00
0) 100 g of dichloroethane was dissolved in 832 g of dichloroethane under heating in a nitrogen atmosphere at 50 ° C. while uniformly stirring, and then 67 g of chloromethyl ether and 11 g of zinc chloride were added, and the mixture was stirred at 50 ° C. for 8 hours.
Allowed to react for hours. Next, the reaction solution was cooled to 30 ° C., precipitated in a large excess of methanol, dried under reduced pressure, dissolved in a chloroform-methanol system, and repurified. The obtained chloromethylated aromatic ether imide polymer has a chlorine content of 6.6% by weight measured by the More method, and the number of introduced chloromethyl groups per repeating unit of the polymer calculated from this chlorine content is It is 1.2.
Furthermore, it was confirmed that this chloromethylated aromatic ether imide polymer was chloromethylated, in agreement with the methylene group concentration appearing at 4.56 ppm evaluated by ¹ H-nuclear magnetic resonance spectrum.

The above chloromethylated aromatic ether imide polymer was dissolved in a solvent of N-methylpyrrolidone to prepare a dope solution of a uniform solution having a concentration of about 20% by weight. A hollow fiber membrane is extruded from an annular nozzle for producing a hollow fiber using this dope solution, and water is used as a coagulating liquid to coagulate from inside and outside of the hollow fiber membrane, and an inner diameter of 0.79 mm consisting of chloromethylated aromatic ether imide and an outer diameter of 1.3. A hollow fiber membrane of mm was obtained.

Next, the above hollow fiber membranes were used at the concentrations of 4-
A hollow fiber membrane made of a modified aromatic ether imide polymer was obtained by immersing in an acetone solution of vinyl pyridine and conducting a reaction treatment at the temperature and time shown in Table 1.

Fourier transform infrared absorption spectrum and
^It was analyzed by ¹³ C-nuclear magnetic resonance spectrum. As a result, it was confirmed from the Fourier transform infrared absorption spectrum that the absorption of the vinyl group had disappeared. ^{In the 13} C-nuclear magnetic resonance spectrum, disappearance of the peak attributed to the vinyl group and appearance of the peak attributed to the methylene chain were confirmed.

Using the separation device of the pervaporation method produced by modularizing 20 hollow fiber membranes having a length of 150 mm obtained above, isopropyl alcohol (IPA) having a concentration of isopropyl alcohol of 85% by weight and water as a liquid to be treated are used. (H ₂ O)
A separation test was performed on the mixed solution of. The liquid to be treated was supplied to the inside of the hollow fiber membrane at a liquid temperature of 60 ° C., and the degree of vacuum on the outside permeation gas chamber side was 3 Torr. From the separation result, Table 1 shows the permeated liquid amount Q (g / m ² · hr) of the hollow fiber membrane and the separation coefficient α = (P _H20 / P _IPA ) / (F _H20 / F _IPA ). However, P _H20 = water concentration (percentage by weight) on the permeate side P _IPA = isopropyl alcohol concentration (percent by weight) on the permeate side F _H20 = water concentration (percent by weight) F _IPA = isopropyl on the permeate Alcohol concentration (wt%) Further, the hollow fiber membrane made of the aromatic ether imide polymer described above is reacted without treatment with 4-vinylpyridine as it is or after reacting with pyridine, and then modularized in the same manner as above, The results of the separation test of the IPA-H ₂ O mixed solution are shown in Table 1 as a comparative example.

Example 2 A hollow fiber membrane made of a chloromethylated aromatic ether imide polymer obtained in the same manner as in Example 1 was mixed with 1 mol / l of 4-vinylpyridine and a photopolymerization initiator (trade name: Darocur1).
116, Merck) 0.03 mol / methanol solution at 25 ℃
Immersion treatment for 15 minutes, then using a high-pressure mercury lamp for photopolymerization, at the output, distance from the light source and time shown in Table 2,
The hollow fiber membrane was irradiated with light under vertical rotation. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane,
The disappearance of the peak attributed to the vinyl group and the appearance of the peak attributed to the methylene chain were confirmed. Each of the obtained hollow fiber membranes was modularized in the same manner as in Example 1 and the results of subjecting it to a separation test of an IPA-H ₂ O mixed solution are shown in Table 2.

Example 3 Immersion treatment and light irradiation were performed in the same manner as in Example 2 and No. 3 except that divinylbenzene was added to the methanol solution of 4-vinylpyridine in Example 2 No. 3 so as to have the concentration shown in Table 3. Then, a hollow fiber membrane was obtained. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane,
The disappearance of the peak attributed to the vinyl group and the appearance of the peak attributed to the methylene chain were confirmed. Table 3 shows the results of subjecting each of the obtained hollow fiber membranes to modularization in the same manner as in Example 1 and subjecting it to a separation test of an IPA-H ₂ O mixed solution.

Example 4 A hollow fiber membrane made of a chloromethylated aromatic ether imide polymer obtained in the same manner as in Example 1 was used, using an amine compound shown in Table 3, with an amine concentration of 1 mol / and a photopolymerization initiator (trade name). : Darocur1116 Merck) 0.03mol /
It was immersed in the methanol solution of No. 3 for 5 minutes at 25 ° C., and then irradiated with light in the same manner as in Example 2 No. Then, heat reaction treatment was carried out in air at 50 ° C. for 8 hours. However, No. 5 and No. 6 were heated and reacted in a methanol solution of methyl iodide at 50 ° C. for 8 hours. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane, disappearance of a peak attributed to a vinyl group and appearance of a peak attributed to a methylene chain were confirmed.

Table 4 shows the results of modularizing each of the obtained hollow fiber membranes in the same manner as in Example 1 and subjecting the resulting hollow fiber membranes to a separation test of an IPA-H ₂ O mixed solution.

Example 5 A hollow fiber membrane made of a chloromethylated aromatic ether imide polymer obtained in the same manner as in Example 1 was treated with an amine compound shown in Table 5 in a methanol solution having an amine concentration of 1 mol / 50 ° C. It was immersed for 8 hours and subjected to a quaternization reaction treatment.
Then, it was immersed for 5 minutes at 25 ° C. in a methanol solution of a photopolymerization initiator (trade name: Darocur1116, manufactured by Merck) at 25 ° C., and then irradiated with light under the irradiation conditions of Example 2 No. 3.

As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane, disappearance of a peak attributed to a vinyl group and appearance of a peak attributed to a methylene chain were confirmed.

Table 5 shows the results of modularizing each of the obtained hollow fiber membranes in the same manner as in Example 1 and subjecting it to a separation test of an IPA-H ₂ O mixed solution.

Example 6 A hollow fiber membrane composed of a chloromethylated aromatic ether imide polymer obtained in the same manner as in Example 1 was used at a temperature of 50 ° C. in a methanol solution having an amine concentration of 1 mol / min using the amine compound shown in Table 6. It was immersed for 8 hours and subjected to a quaternization reaction treatment.

Then, it was immersed in an aqueous solution of ammonium persulfate and sodium sulfite (1,000 ppm each) at 25 ° C. for 8 hours. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane, disappearance of a peak attributed to a vinyl group and appearance of a peak attributed to a methylene chain were confirmed. For each of the resulting hollow fiber membrane, similarly modularized as in Example 1, it showed the results were subjected to separation test of IPA-H ₂ O mixture in Table 6.

Example 7 A hollow fiber membrane made of a chloromethylated aromatic ether imide polymer obtained in the same manner as in Example 1 was placed in a 5 wt% methanol solution of poly-4-vinylpyridine (average molecular weight 5,000) at 50 ° C. for 8 hours. It was dipped and subjected to a quaternization reaction treatment. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane, a peak attributed to a methylene chain was confirmed. The obtained hollow fiber membrane was modularized in the same manner as in Example 1 and subjected to a separation test of an IPA-H ₂ O mixed solution. as a result,
The exchange capacity is 1.3 meq / g, the tensile strength is 520 g / piece, α = 80,
Q = 730.

Example 8 Repeating unit represented by the following formula A hollow fiber membrane made of chloromethylated polysulfone was obtained in the same manner as in Example 1 except that the polysulfone having the formula (P-1700, manufactured by Union Carbide Co.) was used.

The chlor content by the Moer method was 6.3% by weight. The above hollow fiber membrane was immersed in a 1,4-vinylpyridine solution and irradiated with light in the same manner as in Example 2 No. 3. As a result of measuring ¹³ C-nuclear magnetic resonance spectrum of the obtained hollow fiber membrane, disappearance of a peak attributed to a vinyl group and appearance of a peak attributed to a methylene chain were confirmed.

The obtained hollow fiber membrane was modularized in the same manner as in Example 1 and subjected to a separation test of an IPA-H ₂ O mixed solution. As a result, the exchange capacity is 0.73 meq / g, the tensile strength is 580 g / piece, α = 270,
Q = 450.

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Claims (4)

(57) [Claims] 1. An aromatic condensation polymer and a vinyl polymer,
It has a structure in which it is bound by a carbon-nitrogen bond through a quaternary ammonium base, and has an anion exchange capacity of 0.1 to 3.0 me.
A permselective membrane characterized by q / g (dry membrane). 2. An aromatic condensation polymer having a haloalkyl group, and a vinyl monomer having at least one nitrogen-containing group selected from the group consisting of primary amino groups, secondary amino groups and tertiary amino groups. Contact with a monomer to polymerize the vinyl monomer,
The method for producing a selectively permeable membrane according to claim (1), wherein a quaternization reaction is carried out if necessary. 3. An aromatic condensation polymer having a haloalkyl group and a vinyl monomer having at least one nitrogen-containing group selected from the group consisting of a primary amino group, a secondary amino group and a tertiary amino group. The method for producing a selectively permeable membrane according to claim (1), characterized in that the vinyl monomer is polymerized after contacting with a monomer and, if necessary, performing a quaternization reaction. 4. An aromatic condensation polymer having a haloalkyl group and a vinyl polymer having at least one nitrogen-containing group selected from the group consisting of a primary amino group, a secondary amino group and a tertiary amino group. The method for producing a permselective membrane according to claim (1), characterized in that the quaternization reaction is carried out by bringing it into contact with the coalescence.