JPS6043857B2 - Manufacturing method of cation exchange membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cation exchange membrane having acid halide groups only on one side, and more specifically, a method for producing a cation exchange membrane having acid halide groups on only one side. 31■■■・
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1゛-tf4 is substantially converted into a cation exchange group, and then the acid halide group present on the other side is converted into an acid amide group, and the acid halide group remaining in the membrane is further converted into a cation exchange membrane. This invention relates to a method for producing a cation exchange membrane.

BACKGROUND ART Conventionally, it has been known to perform concentration, removal, and separation of salts, acids, and bases, or double decomposition of salts, etc., by electrodialysis using an ion exchange membrane. In particular, in seawater concentrated salt production using an electrodialysis tank with alternating cation exchange membranes and anion exchange membranes, the cation exchange membrane has the property of selectively permeating sodium ions, and this performance is It is required to last semi-permanently and at the same time have other high electrochemical properties. Many attempts have been made to satisfy these various demands.

For example, a method of forming a thin hydrophobic layer with relatively high electrical resistance on the surface of a cation exchange membrane (Japanese Patent Publication No. 36-3164
(Japanese Patent Publication No. 32-1 J541), a method for forming a desulfonated sulfonated rubber on the surface of a cation exchange membrane
(Japanese Patent Publication No. 36-4210), method of thinly coating and adhering a condensed resin having cation exchange groups and highly developed cross-linking on the surface of a cation exchange membrane (Japanese Patent Publication No. 36-4210), cation exchange A method of forming a reaction condensate between a benzene derivative having an amino group or a hydroxyl group on the surface of a membrane and an aldehyde (Japanese Patent Publication No. 38-6647), molecular weight 1
A method in which a substance having a functional group capable of forming a 00 or more cation is uniformly present on the surface of a cation exchange membrane (Japanese Patent Publication No. 46
-23607), a method of forming a cationic, neutral, densely crosslinked thin layer on the surface of a cation exchange membrane using light energy (Japanese Patent Publication No. 1983-383), cation exchange There are many methods, including a method of forming acid amide bonds in the surface layer of the membrane (Japanese Patent Publication No. 46-4208). Some of these methods have already been implemented industrially. However, it was not always satisfactory. As a result of further research, we found that forming a thin cationic layer on the surface of a cation/ion exchange membrane is the best method for selectively permeating low-charge ions such as sodium ions. Preferably, this cationic thin layer is bonded to the cation exchange membrane by a covalent bond, and the functional group present in the cation exchange membrane matrix participating in the bond is a cation exchange group. It was found that an acid halide group that can be easily converted into is desirable.

The inventors of the present invention further conducted various studies from this point of view and found that there was an extremely incomprehensible phenomenon.

That is, for example, as described in Japanese Patent Publication No. 46-42082 and others, even if acid amide bonds are formed only on the surface of a cation exchange membrane, the cation exchange membrane without acid amide bonds may be In some cases, the electrical resistance is close to that of the other, and in other cases, the electrical resistance is extremely high. As a result of further research into the causes of such differences, it was discovered that slight differences in membrane processing conditions can cause significant differences. This lack of stability in the performance of the cation exchange membrane product is an industrial disadvantage, and it is desired that a more stable treatment method be established. As a result of intensive research, the inventors of the present invention have proposed a method for producing a highly stable cation exchange membrane that has extremely high product performance and little variation due to production conditions.

That is, in the present invention, one surface of a polymer membrane in which acid halide groups exist in a statistically uniform distribution is brought into contact with an alkali solution to substantially hydrolyze the acid halide groups, and then the acid halide groups are hydrolyzed. One aspect is characterized in that after reacting the membrane-like material with a primary or (and) secondary amino compound solution, it is further immersed in an alkaline solution to hydrolyze the acid halide groups remaining in the membrane. This is a method for producing a cation exchange membrane having only acid amide groups.

A cation exchange membrane in which an acid amide bond is formed only on one side of the cation exchange membrane is already conceptually known in Japanese Patent Application Laid-Open No. 50-974N.

That is, according to the example described in the publication, one side of a polymer film having a sulfonyl halide acid is reacted with a polyamine, and then the sulfonyl halide group is hydrolyzed.
Although it is possible to produce a cation exchange membrane having an acid amide bond on one side of the membrane using this method, the reaction between acid halide groups and amino compounds, especially polyamino compounds, is generally extremely slow, and the reaction is slow. It takes a long time and that's why. When a low molecular weight amino compound is used, a thick layer of acid amide bonds is formed, and in some cases this may eventually extend to the back side of the membrane. The same can be said about high molecular weight amino compounds, although there are differences in degree since they are aggregates that include small to large molecules. There are no particular problems with this kind of membrane when using a cation exchange membrane in a strong alkaline atmosphere, but when using a cation exchange membrane for electrodialysis of neutral salts such as seawater or underground brine, a layer containing amide groups may be used. Because of the thick layer, when the layer containing amide groups is used for the liquid to be demineralized, it causes a neutral disturbance phenomenon and a rapid increase in the electrical resistance of the membrane. Furthermore, the presence of amide groups on the back surface of the membrane reduces the ability of cation exchange membranes to exclude anions, which is a characteristic characteristic of cation exchange membranes, resulting in a decrease in current efficiency. Therefore, in order to avoid such a neutral disturbance phenomenon, a rapid increase in the electrical resistance of the membrane, and a decrease in the current efficiency of the membrane, it is necessary to carry out the reaction under conditions that substantially prevent the formation of acid amide bonds on the back surface of the membrane. It is. As a specific means for stably obtaining such a membrane, the present invention involves carrying out a hydrolysis reaction of the acid halide group at an extremely high rate on one side of the cation exchange membrane matrix having the acid halide group to form the membrane. After essentially converting the acid halide groups present on one surface into a cation exchange membrane, an acid amide bond is formed on the other surface of the membrane and further hydrolysis is performed again, resulting in extremely excellent electrochemistry. It has now become possible to industrially produce a cation exchange membrane that has excellent performance and selectively transmits ions with a small charge. The content of the present invention will be explained in detail below. In the present invention, the means for treating the cation exchange membrane having acid halide groups, especially the order thereof, are important.

First, only one side of the membrane matrix is hydrolyzed using an alkaline solution to convert it into a cation exchange group (hereinafter also referred to as the first stage), and then an acid amide bond is applied to the other side to form a selective layer. (hereinafter referred to as the subsequent process). By following this sequence, a cation exchange membrane with extremely excellent electrochemical properties can be efficiently produced. The reason for this is that the hydrolysis reaction rate in the first step is very fast, and the thickness of the hydrolyzed layer is rate-limited by the diffusion of the alkaline solution, so appropriate alkali treatment conditions (concentration, temperature, time, etc.)
If you choose , the alkaline solution will not diffuse through the membrane and reach the surface layer on the opposite side, and therefore the acid halide groups on the front and back sides of the opposite side will exist stably, and once converted in the previous step. Cation exchange membranes are inert to primary and/or secondary amino compounds that are used as processing agents in later steps that require longer reaction times, making it easier to perform later steps that affect selectivity. It is from.

In other words, it is extremely easy to treat only the required surface by immersing it in a primary or (and) secondary amino compound solution without considering the alkali-treated surface (the surface converted to a cation exchange group). The point is that it is easy and efficient to work. Furthermore, in the present invention,
It is necessary to treat the membrane again with an alkaline solution to sufficiently hydrolyze the acid halide groups that are likely to remain inside the membrane.

At first glance, this two-stage hydrolysis seems to be disadvantageous from an industrial perspective, but only by the procedure of the present invention can a modified cation exchange membrane with extremely stable electrochemical performance be produced.
It has the great advantage of being extremely easy to obtain. The method for producing the polymer membrane in which the acid halide groups used in the present invention are present in a statistically uniform distribution is not particularly limited, but generally a compound having acid halide groups in the molecule is used as one component, Alternatively, a method in which an acid halide group is introduced after a polymer film is made using a compound that can be converted into an acid halide group through a reaction, or a method in which an exchange group in a cation exchange membrane is converted into an acid halide through a reaction. etc. will be adopted.

Examples of compounds having an acid halide group in the molecule include vinylsulfonyl halides, styrenesulfonyl halides, arylsulfonyl halides, perfluor 3 and 6
Examples include alkylvinylsulfonyl halides such as -dioxer-4-methyl-7-octensulfonyl halide, acrylic acid halides, methacrylic acid halides, halosulfonated polyethylene, halosulfonated polystyrene, and halosulfonated polyphenylene.

Compounds that can be converted into acid halide groups by reaction include styrene, vinylnaphthalene, vinyltoluene, chlorostyrene, hydroxylstyrene,
There are polystyrene, styrene non-butadiene rubber, polyphenylene, etc. These compounds are formed into a polymer membrane as one component and then halosulfonylated with a halosulfonic acid such as chlorosulfonic acid to produce a cation exchange membrane with acid halide groups. Make it the mother body. In addition, sulfuric acid, chloroform, carbon tetrachloride, 1.
It is also possible to use 2-dichloroethane or the like. Furthermore, in order to convert the exchange groups of the cation exchange membrane, ie, sulfonic acid groups, carboxylic acid groups, phosphoric acid groups, etc., into acid halide groups, it is necessary to react them with phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, thionyl chloride, etc. Bye.

At this time, carbon tetrachloride, 1,2-dichloroethane, chloroform, etc. may be used. Note that compounds in which the acid halide group is bonded to an aromatic ring are advantageous because the acid halide compound can be easily synthesized and an acid amide group can be formed under relatively mild conditions. In the present invention, it is necessary to introduce a cation exchange group onto only one side of the polymer membrane having acid halide groups.

Introduction of a cation exchange group can be easily carried out by contacting with a neutral, acidic, or alkaline solution and hydrolyzing it, but in the present invention, it is preferable to use an alkaline solution with a high hydrolysis rate. It is essential to use it. The method of bringing the polymer membrane into contact with an alkaline solution is not particularly limited as long as only one side of the membrane is brought into contact.

For example, two membranes are placed together in a tightening frame, tightened using rubber gaskets, and then immersed in an alkaline solution so that only the outer surfaces contact, or by applying an alkaline solution to only one side of the membrane with a brush or roll coater. by spraying the alkaline solution onto only one side of the membrane; by bringing one side of the membrane into contact with a solid surface wetted or covered by the alkaline solution; by placing only one side of the membrane in contact with the alkaline solution surface; Methods such as floating the membrane and stirring the alkaline solution below, or allowing the alkaline solution to flow down on one side of the membrane to prevent it from getting around to the other side, etc., are employed. Among these various methods, a method in which the solid surface wetted or covered with an alkaline solution is brought into contact with a polymer film having an acid halide group is the easiest way to carry out this step industrially. This is most preferred because it can be easily processed continuously and uniformly. An example of this aspect will be explained using figures. FIG. 1 is a schematic explanatory diagram, and FIG. 2 is a plan view thereof.

In the figure, 1 is a polymer film-like material having an acid halide group,
It is placed on a support feed roller 2. 3 is a container having a large number of holes 4 only on its upper surface, and the alkaline solution contained in the tank 5 is made to overflow from the holes 4 of the container 3 using a pump 6.

By doing so, the surface of the container 3 becomes uniformly wetted or covered with the alkaline solution, and comes into contact with the lower surface of the polymer film 1. In this method, continuous processing is possible by rotating the supporting and feeding roller 2 at a constant speed. Further, it is preferable that the width of the processing container 3 is slightly shorter than that of the polymer membrane material, since this prevents the alkaline solution from scattering and entering the other surface. The length of the processing container 3 to be brought into contact is arbitrary, but it is usually from 10C7n to 2m. It is preferable to use a length up to 100cm as it does not require space. The alkaline solution used to substantially hydrolyze the acid halide group on one side of the polymer membrane and introduce the cation exchange group is sodium hydroxide, potassium hydroxide, lithium hydroxide, barium hydroxide, etc. hydroxide, trimethylamine, triethylamine,
Tertiary amines such as triethanolamine and pyridine,
benzyltrimethylammonium hydroxide,
Alkali components such as quaternary amine hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide are mixed with water, methanol,
It is a solution dissolved in a solvent such as ethanol, propyl alcohol, or acetone in an arbitrary ratio.

The alkaline component in the solution is 0.1 to 50%, preferably 3
~25%. An alkaline solution having a temperature of 5 to 100°C is usually used. The contact time between one side of the membrane and the alkaline solution depends on the type of polymer membrane containing acid halide groups,
It varies depending on the composition of alkaline solution, temperature, and contact method.
If the concentration and temperature of the alkaline solution are increased and the contact time is increased, the thickness of the layer in which acid halide groups are converted to cation exchange groups will increase.

The thickness of the membrane-like material having acid halide groups is limited, and treatment conditions must be selected so that the acid halide group does not become a cation exchange group up to the surface layer of the other side 1. Therefore,
The treatment time for one side of the alkaline solution varies depending on the type of polymer membrane having acid halide groups, the composition of the alkaline solution, the temperature, and the contact method, but is usually selected from 10 seconds to 2 hours. In addition, in order to continuously perform single-sided alkaline solution treatment, a short time of 1 minute to 2 powders is preferable. In order to obtain such a short treatment time, it is preferable that the concentration of the alkali metal hydroxide be 10 to 40% and the temperature be 20 to 100°C. After replacing the acid halide groups on only one side of the polymer film having acid halide groups with cation exchange groups as described above, the membrane is immersed in an acidic solution such as hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid. , prevents the progress of hydrolysis of acid halide groups. Next, the polymer membrane with acid halide groups on one side as cation exchange groups is generally washed with water, and then subjected to a later step in which the acid halide groups remaining on the other side are converted to acid amide groups to form a selective layer. Ru.

Amino compounds and polymers having amino groups are used to convert acid halide groups into acid amide groups.

Specifically, the amino compound and the polymer having an amino group must have at least one primary or secondary amino group. Examples of these compounds and polymers include aniline, ethylenediamine, diethylenetriamine, triethylenetetramine, tetramethylenediamine, tetraethylenepentamine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, piperazine, and ethanol. Amines, diethanolamine, para-aminosalicylic acid or its sodium salt, meta-aminosalicylic acid or its sodium salt, amino acids (
Glutamic acid or sodium salt, histidine, valine, glycine, ornithine, tyrosine, leucine, cysteine, cystine, asparagine, aspartic acid, alanine, serine, diencholic acid, aminobutyric acid, threonine, norvaline, methionine, leucine, isoleucine, citrulline, phenylalanine , diiodotyrosine,
DL-, D-, L-type amino acids such as thyroxine, dioxyphenylalanine, dipromtyrosine, proline, oxyproline, tryptophan, arginine, lysine, canavanine, thiolhistidine), aminonaphthylene sulfonic acids, aminopicoline, aminopterin , aminoquinolines, aminophenols, aminomethylphenols, aminomethylthiazoles, aminobenzoic acids, amidol, aminoacetophenone, aminobenzophenone, vitamins having a primary or secondary amino group such as vitamin VIII, VIII, Iminodiacetic acid, 2●4 dinitrophenylhydrazine, 0-, m-, p-aminobenzoic acid, o-, m-, p-aminostyrene, ethyleneimine, o
-, m-, p-phenylene diamine, arsanilic acid, dicyandiamide, isonicotinic acid, hydrazide, phthalimide, phenylglycine, monoalkylamine, dialkylamine, Bismarck brown, auracin conc, madienta, chrysidein, crystal, etc. dyes, polyethyleneimine, polyvinylamine, polyaminostyrene, polyvinylimidazole, and some of the amino groups of the above-mentioned compounds having two or more amino groups in the molecule, such as methyl chloride, ethyl chloride, odor Alkyl halides such as methyl chloride, ethyl bromide, methyl iodide, ethyl iodide, benzyl chloride,
Partially alkylated with dimethyl sulfuric acid, epichlorohydrin, etc., polychloromethylstyrene, epichlorohydrin rubber, chloroprene rubber, epoxidized polybutadiene, etc. with ammonia and one or more primary amines, such as methylamine, ethylamine, propylamine, aniline, These are compounds that are partially aminated with arylamine, benzylamine, etc., and then subjected to an additional quaternary amination reaction with trimethylamine, triethylamine, triethanolamine, pyridine, etc. Of these compounds,
Molecular weight 50 or more, one or more primary molecules in the molecule or (and)
Compounds with secondary amines, such as polyethyleneimine, are particularly preferably used.

An amino compound or a polymer having an amino group is dissolved in a solvent selected from among solvents in which these compounds are dissolved and acid halide groups and amino groups do not easily react, such as water, methanol, ethanol, etc., to form a solution. Alternatively, the liquid version can be used as is.

The contact between the solution of these amino compounds or polymers having amino groups (hereinafter also simply referred to as amino compounds) and the membrane is as follows:
There is no need to take care not to contact the other side as in the case of conversion to the ion exchange group described above.

One side, into which an ion exchange group has already been introduced, will not cause any trouble even if it comes into contact with a solution of an amino compound or the like. Therefore, in the amide group forming reaction, it is common to adopt a mode in which the entire membrane is immersed. Further, since this reaction requires a relatively long time, it is easy to adopt the immersion method from this point of view as well as from the point of view of uniform formation of the selective layer. Other contact methods include methods such as applying to one side or spraying. The contact time is generally longer than the ion exchange group introduction treatment time in the previous step, and is about 30
It lasts for about 7 days.

The reaction may be carried out under normal pressure, increased pressure, or reduced pressure, but normal pressure is preferable. Further, the reaction temperature is from 10°C to the boiling point of the amino compound to be subjected to the reaction, but a temperature of 20°C to 70°C is usually preferred. In addition, in the reaction of converting an acid halide group into an acid amide group, a tertiary amine such as trimethylamine, triethylamine, triethanolamine, pyridine, benzyltrimethylammonium hydroxide, tetramethylammonium hydroxide, etc. is used as a dehydrochlorination agent to accelerate the reaction. Quaternary amine hydroxides such as hydroxide, tetraethylammonium hydroxide, and even sodium hydroxide,
Potassium hydroxide, lithium hydroxide, etc. may be added.

In the present invention, the degree of conversion to acid amide groups is preferably limited to the surface of the membrane or the so-called surface layer near the surface; if the inside of the membrane is converted to acid amide groups, the membrane resistance increases and This is undesirable because it causes sexual disturbance.

In general, the thickness of the acid amide base layer is 50μ or less, preferably 10μ
It is better to set it to less than μ. The thickness of the acid amide base layer can be controlled relatively easily by adjusting the reaction solution concentration, reaction temperature, reaction time, etc. A membrane whose surface layer has been converted to acid amide groups cannot be used as is because acid halide groups remain inside the membrane.

For this reason, hydrolysis takes place. Generally, the acid halide groups may be converted to cation exchange groups by immersing the membrane in an alkaline solution. The alkaline solution used here may be the same as that described above, and it is desirable that the immersion time be sufficient to completely hydrolyze the acid halide groups inside the membrane. Then, by immersing the membrane in an acidic solution to neutralize the alkaline components and washing it with water, a highly electrically conductive cation exchange membrane with a selective layer on one side, that is, a layer that allows cations with a small charge to pass through, is obtained. be able to. The cation exchange membrane obtained by the present invention can be used for various purposes. For example, an electrodialysis tank is constructed in which cation exchange membranes and anion exchange membranes are alternately arranged so that the side with the acid amide group of the cation exchange membrane faces the liquid to be desalinated, and an anode and a cathode are provided at both ends. Desalt using
Preferably used when performing concentration etc., when arranging multiple cation exchange membranes to separate ions or isotopes, similarly when arranging multiple cation exchange membranes for debasing, etc. be done. In particular, the cation exchange membrane obtained in the present invention has the advantages of high current efficiency for sodium and ion, high electrical conductivity of the membrane, and the ability to easily manufacture the membrane industrially. It can be effectively used in salt production using an ion exchange membrane method to obtain sodium chloride by concentrating seawater.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

The performance of the cation exchange membrane produced according to the present invention was measured by the following method.

(1) Membrane resistance R (unit: ΩCTI)
j The cation exchange membrane was sufficiently equilibrated with 0.5N sodium chloride at 25°C, and then measured using an AC bridge for 1000 cycles.

(2) Pure salt rate βNa+K (unit: percent) The surface of the cation exchange tetra-exchange membrane with the selective layer obtained in the present invention is directed toward the side to be desalted, and the anion exchange membrane is arranged alternately with the anion exchange membrane to obtain an effective Seawater was continuously concentrated using an electrodialysis tank with a membrane area.

Note that the seawater flow rate is 6CTnIsec1, the temperature is 30°C, and the current density is 3A1dd. After starting electrodialysis, when the concentrate reached equilibrium, the chloride ion concentration CCl, calcium ion, and magnesium ion concentration CCa+Mg were measured, and βNa+K was determined from the following formula.

Note that CNa+K is the concentration of sodium ions and potassium ions in the concentrate.

Furthermore, the pH of the concentrated solution was also measured at the same time.

(3) Current efficiency of chloride ions ηCI (unit: percent)
In order to investigate the extent to which chlorine ions, which are anions, leak from the cation exchange membrane during seawater concentration, the current efficiency of chlorine ions was measured.

The anion exchange membranes were all equipped with membranes with the same performance, and the same apparatus used in measuring the pure salt ratio in (2) was used. The current efficiency was determined from equation (3) from the amount v of the liquid overflowing from the concentration chamber during a certain amount of current Q after the concentrated liquid reached equilibrium and the chlorine ion concentration CCl. (4) Amount of sulfonic acid amide group ν1330/ν830I of 1330 cm-1 based on the sulfonic acid amide group which is one of the acid amide groups
The amount of sulfonic acid amide groups present in the membrane surface layer was simply investigated from the ratio of the absorption peak height ν1330 of the R spectrum and the absorption peak height ν830 of 830 cm-1 based on the aromatic ring substituted product. .

The membrane surface on which the sulfonic acid amide group was attempted to be formed was designated as the front, and the opposite membrane surface was designated as the back. And I.R.
A 10μ sample was scraped off from the front and back surfaces and measured using the KBr tablet method. Example 1, Comparative Examples 1 to 3 Example 1 Styrene Co., Ltd., 55% purity divinylbenzene 10
A viscous paste mixture consisting of 1 part of tributyl acetyl citrate, 1 part of finely divided polyvinyl chloride powder, and 1 part of benzoyl peroxide was applied to a polyvinyl chloride cloth, and the mixture was heated at a temperature of 110°C for 4 hours. Polymer film-like material was obtained by heating and polymerizing for a period of time.

Next, this membrane was immersed in a mixed solution of chlorosulfonic acid monosulfuric acid (1:1) for 40'Cl3 to form an acid halide.

Thereafter, the mixture was successively diluted with sulfuric acid and washed with water to obtain a polymer film having an acid halide group (chlorosulfonyl group). Furthermore, in order to convert the acid halide group on only one side into a cation exchange group, the membrane was brought into contact with the surface of a 30'CllO% sodium hydroxide aqueous solution for 2 minutes using the apparatus shown in Figure 1, and then IN hydrochloric acid Soaked in water and washed.

After directly drying a portion of this membrane under reduced pressure, the surface layer of the membrane was
μ was scraped off and the IR spectrum was examined.

No absorption at 1375 cm-1 due to chlorsulfone groups was observed on the surface in contact with sodium hydroxide, but there was a large absorption on the surface layer on the opposite side, which was comparable to the IR spectrum of the membrane immediately after chlorsulfonation. It was due to the absorption of Thereafter, the membrane was immersed in a 10% aqueous solution of the amino compound shown in Table 1 under the conditions shown in Table 1 to form acid amide groups, and the acid halide groups remaining inside were further removed by 10%.
It was immersed in an aqueous sodium hydroxide solution at room temperature for 2 hours for hydrolysis.

Thereafter, the cation exchange membrane of the present invention was obtained by washing with water and immersing in each aqueous solution of IN hydrochloric acid and 0.5N sodium chloride. When various properties such as the amount of sulfonic acid amide groups on the front and back sides of these membranes, membrane resistance, pure salt ratio, chlorine ion current efficiency, and pH of the concentrated solution were measured, the results shown in Table 1 were obtained. . Among various amino compounds, membranes using polyethyleneimine as a processing agent have low membrane resistance, extremely high pure salt ratio, and extremely high current efficiency, and exhibit very little performance deterioration even after continuous concentration for 6 months. Ta. Comparative Example 1 Two sheets of the polymer film having acid halide groups obtained in Example 1 were set in a stainless steel frame and tightened using a rubber gasket.

This frame was immersed in an aqueous solution of the amino compound of Example 1, and the same treatment as in Example 1 was performed to obtain a membrane of Comparative Example 1. The properties of these films are shown in Table 1. In films using relatively low molecular weight amino compounds such as ethylenediamine and diethylenetriamine as processing agents, amide groups are formed inside the film and even on the surface layer on the opposite side. As a result, the membrane resistance was extremely high, making it unsuitable for use as a cation exchange membrane for electrodialysis. In addition, the membrane using polyethyleneimine as a treatment agent had a higher membrane resistance than the membrane of Example 1, probably because the acid amide groups were formed deep inside the membrane, and the pH of the concentrated solution decreased slightly, resulting in a neutral disturbance phenomenon. was waking up.

Comparative Example 2 The polymer film having an acid halide group obtained in Example 1 was immersed in an aqueous solution of an amino compound shown in Table 1, and the same treatment as in Example 1 was carried out.

As shown in Table 1, the properties of the resulting membrane were such that, because acid amide groups were formed on both sides of the membrane, the membrane had a significantly low current efficiency for chlorine ions. Comparative Example 3 Various properties were also measured for a membrane obtained by directly hydrolyzing the entire surface of the polymer membrane having acid halide groups obtained in Example 1 with a 10% aqueous sodium hydroxide solution at room temperature for 2 hours.

This is also listed in Table 1. MW is the molecular weight of polyethyleneimine.

Example 2, Comparative Examples 4 to 5 Example 2 Styrene sulfonyl chloride was synthesized from potassium ballastyrene sulfonate and phosphorus pentachloride, and this 9(2), 1 divinylbenzene with a purity of 55%, 5 parts of styrene butadiene rubber, A viscous mixed solution consisting of 3 parts of benzoimenole peroxide was applied to a cloth made of polyvinyl chloride, and heated at 80°C for 8 hours.
Polymer film-like material was obtained by heating and polymerizing for a period of time.

One side of this membrane was coated with a solution of 10% sodium hydroxide aqueous solution to which 5% acetone was added using the apparatus shown in Figure 1.
The contact was made for 0 minutes.

Thereafter, it was immersed in 1N hydrochloric acid and washed with water. This membrane was immersed in a 10% amino compound aqueous solution shown in Table 2 to carry out an acid amide group formation reaction. After this, the acid halide groups remaining inside the membrane were hydrolyzed by immersion in a sodium hydroxide-water-methanol mixture at 60° C. for 5 hours. After this, wash with water,
The cation exchange membrane of the present invention was obtained by sequentially immersing it in IN hydrochloric acid and 0.5N sodium chloride aqueous solutions. The properties of these films are shown in Table 2. Comparative Examples 4 to 5 For comparison, Comparative Example 4 in which one side was not subjected to alkali treatment and both sides were immersed in the amino compound aqueous solution of Example 2, and Comparative Example 5 in which the polymer membrane of Example 2 was only subjected to hydrolysis treatment. A film was also obtained.

The properties of this film are also listed in Table 2. Example 3, Comparative Example 6 Example 3 Styrene (4) parts, 55% pure divinylbenzene 10
A paste mixture consisting of 1 (1) part of polyethylene fine powder, 25 parts of dioctyl phthalate, and 2 parts of benzoyl peroxide was applied to a polypropylene cloth, and
C. for 4 hours to obtain a polymer film.

This was heated at 60°C with 98% sulfuric acid. ．． 811r sulfonation, then sequentially diluted with sulfuric acid, and further washed with methanol and carbon tetrachloride. Thereafter, the membrane was immersed in a mixed solution of (9) parts of phosphorus oxychloride and m parts of carbon tetrachloride at 50°C for 16 hours to convert the sulfonic acid groups into acid halide groups.
Thoroughly washed with carbon chloride and methanol. A 20% aqueous potassium hydroxide solution was applied to one side of the membrane using a roll coater, and after 10 minutes, the membrane was immersed in hydrochloric acid and washed with water. Furthermore, this film was aminated with 5% of a compound obtained by aminating epoxidized polybutadiene BF-1000 (trade name; manufactured by Nippon Soda Co., Ltd.) with a 1:2 mixture of methylamine and trimethylamine.
It was immersed in an aqueous solution at 30°C for 4 hours. After that, it was immersed in a 10% potassium hydroxide aqueous solution at room temperature for 2 hours, and then diluted with hydrochloric acid and 0.5%.
The cation exchange membrane of the present invention was obtained by immersing it in each aqueous solution of 5N sodium chloride. When various properties of this film were measured, the results shown in Table 3 were obtained. Comparative Example 6 Two sheets of the polymer film having acid halide groups obtained in Example 3 were set in a stainless steel frame and tightened using a rubber packing.

This frame was immersed in an aqueous solution of the amino compound of Example 3, and the same treatment as in Example 3 was performed to obtain a membrane of Comparative Example 6. Various properties of this film are also shown in Table 3. Example 4, Comparative Example 7 Example 4 A paste-like mixture consisting of a scoop of methacrylic acid, 5 parts of styrene, 2 parts of divinylbenzene with a purity of 55%, 10 parts of fine polyethylene powder, 25 parts of dioctyl phthalate, and 2 parts of benzoyl peroxide. was coated on a polypropylene cloth, and then heated and polymerized at 110° C. for 4 hours to obtain a polymer film.

This was sulfonated with % sulfuric acid at 60° C. for 8 hours, successively diluted with sulfuric acid, and then washed with methanol and carbon tetrachloride. Next, this membrane was immersed in a mixed solution consisting of (4) parts of trichloride and 5 parts of carbon tetrachloride at 40° C. for 24 hours to convert the carboxylic acid groups to acid halide groups. Next, this membrane was washed with carbon tetrachloride and methanol, and then 20% sodium hydroxide was applied with a brush to one side of the membrane. After 5 minutes, it was immersed in hydrochloric acid and washed with water.

Then, 5% polyethyleneimine (NW3OOO~7
000) in an aqueous solution at 40°C for 2 days, and further
Immerse in 0% sodium hydroxide aqueous solution for 2 hours at room temperature,
The cation exchange membrane of the present invention was obtained by immersing it in each aqueous solution of N hydrochloric acid and 0.5N sodium chloride.

Table 4 shows the properties of this film. Comparative Example 7 Various properties of the membrane subjected to only sulfonation in Example 4 were also measured for comparison.

Claims (1)

[Claims] 1. One surface of a polymer membrane in which acid halide groups exist in a statistically uniform distribution is brought into contact with an alkaline solution to substantially hydrolyze the acid halide groups, and then the acid halide groups are substantially hydrolyzed. One aspect is characterized in that after reacting the membrane-like material with a primary or (and) secondary amino compound solution, it is further immersed in an alkaline solution to hydrolyze the acid halide groups remaining in the membrane. A method for producing a cation exchange membrane having only acid amide groups. 2. The method according to claim 1, wherein the primary or/and secondary amino compound has a molecular weight of 50 or more. 3. The method according to claim 1, wherein the acid halide group is bonded to an aromatic ring. 4. Claim 1, in which one surface of the film-like object is brought into contact with the alkaline solution by means of bringing the film-like object into contact with a solid surface wetted or covered with the alkaline solution.
The method described in section. 5. The method according to claim 1, wherein the amino compound is polyethyleneimine.