JP3193522B2 - Method for producing ion exchange membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ion exchange membrane, and more particularly to a method for producing an ion exchange membrane having good durability against high temperatures, acids, alkalis and organic solvents.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing an ion exchange membrane,
In general, a resin that functions as a matrix without introducing ion-exchange groups into a mixed solution containing a functional group suitable for introducing ion-exchange groups or a monomer having an ion-exchange group, a crosslinking agent and a polymerization initiator as main components ( A method in which a paste obtained by adding a matrix resin) is applied to a woven fabric of polyvinyl chloride, polyolefin, or the like, polymerized, and then ion-exchange groups are introduced as necessary (hereinafter, simply referred to as a matrix resin). Paste method) is widely used. Here, as the matrix resin, for example,
It is possible to use a polymer compound dispersible in the above monomer mixture such as ethylene-propylene copolymer and polybutylene, and a polymer compound soluble in the above monomer mixture such as polystyrene and styrene-butadiene copolymer. Are known.

[0003]

However, when a saturated aliphatic hydrocarbon polymer such as an ethylene-propylene copolymer or polybutylene is used as the matrix resin, the resin is a functional group suitable for introducing ion-exchange groups. Since the compatibility with the monomer having a group is not sufficient, the two do not mix well, and the resulting ion exchange resin becomes unsatisfactory in electrochemical performance, durability during use, and the like. On the other hand, when polystyrenes are used, the resin is inferior in flexibility, and the resulting ion exchange membrane is not satisfactory in flexibility and the like.

[0004] In this respect, the styrene-butadiene copolymer has good compatibility with a monomer having a functional group suitable for introducing an ion exchange group, and has good mechanical properties such as flexibility of a resin. Yes, it is suitably used as the matrix resin. However, the resin has an unsaturated bond in the molecule, so the chemical stability is not sufficient, and therefore, an ion exchange membrane using the resin as a matrix resin,
When used for a long period of time, especially under severe conditions such as contact with acids and alkalis, the ion exchange resin part is deteriorated, and the ion exchange resin part is partially peeled off from the substrate. Occurs.

[0005] From such a background, it has excellent electrochemical properties and mechanical properties such as flexibility, and is subjected to severe conditions such as exposure to high temperatures or contact with acids, alkalis or organic solvents. It has been desired to develop an ion-exchange membrane having good durability even when used in the field.

[0006]

Means for Solving the Problems The present inventors have intensively studied in view of the above problems. As a result, by using a copolymer of a specific monomer unit derived from an aliphatic hydrocarbon-based monomer and a monomer unit based on a styrene-based monomer as the matrix resin, the above-described problem is solved. The inventors have found that the present invention can be solved, and have completed the present invention.

That is, the present invention provides a monomer derived from a monomer having a functional group or an ion exchange group suitable for introducing an ion exchange group, a crosslinking agent, a polymerization initiator and an aliphatic hydrocarbon monomer. Unit, in a state where a copolymer is formed, a copolymer of a monomer unit having no unsaturated bond in the monomer unit and a monomer unit based on a styrene-based monomer. A method for producing an ion-exchange membrane, comprising adhering a mixture to a substrate and subjecting the mixture to polymerization polymerization, and then introducing an ion-exchange group as necessary.

In the production method of the present invention, the matrix resin is a monomer unit derived from an aliphatic hydrocarbon-based monomer, and in a state where a copolymer is formed, the monomer unit is contained in the monomer unit. A copolymer of a monomer unit having no unsaturated bond and a monomer unit based on a styrene monomer is used. Such a copolymer is excellent in compatibility, flexibility and the like with a monomer having a functional group suitable for introducing an ion exchange group, and has good chemical stability. The ion exchange membrane obtained as above has remarkably excellent durability in use, in addition to mechanical properties such as flexibility and electrochemical properties.

Here, the copolymer of the specific monomer unit derived from the aliphatic hydrocarbon-based monomer and the monomer unit based on the styrene-based monomer includes the above-mentioned constituent units. Known compounds are used without any restriction. As the styrene-based monomer constituting the copolymer, there are no restrictions on styrene or a styrene-substituted product obtained by introducing a substituent such as a halogen group, an alkyl group or a haloalkyl group into an aromatic ring or a vinyl group of the styrene. Used without. Examples of such a styrene-substituted product include vinyltoluene, vinylxylene, chlorostyrene, chloromethylstyrene, α-methylstyrene, α-halogenated styrene, α, β, β′-trihalogenated styrene and the like.

On the other hand, the aliphatic hydrocarbon-based monomer which is another component of the copolymer is an unsaturated aliphatic hydrocarbon, preferably an unsaturated aliphatic hydrocarbon having 2 to 9 carbon atoms. Is used without particular limitation. In that case, as the unsaturated aliphatic hydrocarbon, specifically, ethylene,
It is preferable to use olefins such as propylene and butylene and conjugated diolefins such as butadiene and isoprene.
In the present invention, the copolymer used as the matrix resin is a monomer unit derived from an aliphatic hydrocarbon-based monomer, in a state where the copolymer constitutes the monomer unit It has no unsaturated bond. Therefore, when an aliphatic hydrocarbon monomer having a plurality of unsaturated bonds such as the conjugated diolefin is used as a copolymer component, the copolymer is further subjected to a hydrogenation treatment after the copolymerization to give the monomer. It is necessary to eliminate the unsaturated bonds remaining in the base unit. In addition, as a form of copolymerization, a so-called A
Any type such as -B type diblock type, ABA type triblock type, or random type may be used.

In the present invention, a copolymer of a specific monomer unit derived from the aliphatic hydrocarbon-based monomer most preferably used and a monomer unit based on a styrene-based monomer is preferably used. , Copolymerizing styrene monomer and butadiene,
Examples of the resin include a resin obtained by further hydrogenating the obtained copolymer. When the copolymer having an unsaturated bond is subjected to a hydrogenation treatment, some unsaturated bonds may remain in the obtained copolymer. Usually, the number of such residual unsaturated bonds is preferably within 10%, preferably within 5% of the total number of unsaturated bonds before the hydrogenation treatment.

In the copolymer of the specific monomer unit derived from the aliphatic hydrocarbon-based monomer and the unit based on the styrene-based monomer, the content of each structural unit is particularly limited. However, considering the compatibility with the monomer having a functional group suitable for introducing an ion-exchange group and the flexibility of the obtained copolymer, the unit based on the styrene-based monomer is a copolymer. Is preferably 10 to 80% by weight based on the total weight of Although the molecular weight of the copolymer is not particularly limited, it is usually 1,000 to 1,000,000.
Preferably, it is in the range of 50,000 to 500,000.

Next, a monomer having a functional group or an ion exchange group suitable for introducing an ion exchange group, a crosslinking agent and a polymerization initiator, which are mixed with the matrix resin, will be described. First, as a monomer having a functional group or an ion exchange group suitable for introducing an ion exchange group used in the present invention, a monomer used in the production of a conventionally known ion exchange membrane is not particularly limited. used.
Specific examples include styrene, vinyl toluene, vinyl xylene, α-methyl styrene, acenaphthylene, vinyl naphthalene, α-halogenated styrene, α, β, β′-trihalogenated styrene, chlorostyrenes, and the like. Particularly in the case of a cation exchange membrane, α-halogenated vinyl sulfonic acid, α, β, β′-halogenated vinyl sulfonic acid, methacrylic acid, acrylic acid, styrene sulfonic acid, vinyl sulfonic acid, maleic acid, itaconic acid , Styrene phosphonylic acid, maleic anhydride, vinyl phosphoric acid, and the like, and salts and esters thereof. In the case of an anion exchange membrane, vinyl pyridine, methyl vinyl pyridine, ethyl vinyl pyridine, ethyl vinyl pyridine, vinyl pyrrolidone, vinyl carbazole,
Vinyl imidazole, aminostyrene, alkylaminostyrene, dialkylaminostyrene, trialkylaminostyrene, methyl vinyl ketone, chloromethylstyrene, acrylamide, acrylamide, oxime, vinylpyrrolidone, styrene, vinyltoluene and the like are used.

As the cross-linking agent, a conventionally known monomer used in the production of an ion exchange membrane is used without any particular limitation. Specific examples include divinyl compounds such as m-, p-, o-divinylbenzene, divinylsulfone, butadiene, chloroprene, isoprene, trivinylbenzenes, divinylnaphthalene, diallylamine, triallylamine, and divinylpyridines. .

Further, as the polymerization initiator, a conventionally known polymerization initiator is used without any particular limitation, and may be appropriately selected according to the base material of the ion exchange membrane to be used and the molding conditions. For example, in the case of using a polyvinyl chloride material as the substrate, in consideration of the melting point of the substrate, use a radical polymerization initiator having a decomposition temperature of 110 ° C. or lower to obtain a half-life of 10 hours, It is recommended to set the polymerization temperature below 80 ° C. Examples of the radical polymerization initiator having a decomposition temperature of 110 ° C. or lower for obtaining the above half-life of 10 hours include benzoyl peroxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexane peroxide, methyl cyclohexane peroxide, and isobutyl. Peroxide, 2,4-dichlorobenzoyl peroxide, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, p-chlorobenzoyl peroxide, 1,1-dioxide -Tert-butylperoxy-trimethylcyclohexane, 1,1-di-tert-butylperoxycyclohexane, 2,2
-Di- (tert-butylperoxy) -butane, 4,
4-di-tert-butylperoxyvaleric acid-n
-Butyl ester, 2,4,4-trimethylpentylperoxy-phenoxyacetate, α-cumylperoxyneodecanoate, tert-butylperoxyneodecanoate, tert-butylperoxypivalate, tert-butylpert Oxy-2-ethylhexanoate, tert-butylperoxy-isobutyrate, di-tert-butylperoxy-hexahydroterephthalate, di-tert-butylperoxyazelate, tert-butylperoxy-3,5,5 -Trimethylhexanoate, tert-butyl peroxyacetate, tert-butyl peroxybenzoate and the like are used.

On the other hand, when a polyolefin substrate is used, the decomposition temperature for obtaining a half-life of 10 hours is 110 ° C.
It is recommended to use a radical polymerization initiator having a temperature of from 170C to 170C and to set the polymerization temperature to 110C or more. The decomposition temperature for obtaining the above half life of 10 hours is 110 ° C. to 17 ° C.
Examples of the radical polymerization initiator at 0 ° C. include p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, α, α′-bis (tert-butylperoxy-m-isopropyl) benzene, di-ter
t-butyl peroxide, tert-butyl hydroperoxide, di-tert-amyl peroxide, ter
t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl 2,5-di (tert-butyl peroxy) hexane, 2,5-dimethyl 2,5-di (t
tert-butylperoxy) hexyne-3, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethyl 2,5-dihydroperoxyhexane, 2,5-dimethyl 2 , 5-dihydroperoxyhexine-3 and the like are used.

In the present invention, a mixture of a monomer having a functional group or an ion-exchange group suitable for introducing an ion-exchange group, a crosslinking agent, a polymerization initiator and the matrix resin described above may be used, if necessary. As a monomer having a functional group suitable for introducing the ion exchange group and a monomer copolymerizable with a crosslinking agent, for example, styrene, acrylonitrile,
Ethyl styrene, vinyl chloride, acrolein, methyl vinyl ketone, maleic anhydride, maleic acid, salts or esters thereof, itaconic acid, salts or esters thereof, and the like may be appropriately mixed. Further, a plasticizer such as dioctyl phthalate, dibutyl phthalate, tributyl phosphate, styrene oxide or an alcohol ester of an aliphatic acid or an aromatic acid, or a solvent for diluting the monomer may be appropriately added.

In the present invention, the mixing ratio of each component described above is not particularly limited, but generally, 100 parts by weight of a monomer having a functional group or an ion exchange group suitable for introducing an ion exchange group. To the crosslinking agent
Parts by weight, 2 to 200 parts by weight of a copolymer of a specific monomer unit derived from the aliphatic hydrocarbon-based monomer and a monomer unit based on the styrene-based monomer, A monomer copolymerizable with a monomer having a functional group suitable for introduction is in the range of 0 to 200 parts by weight, and the polymerization initiator is added in an amount of 0.1 to 100 parts by weight of the total monomer. It is preferred to mix in the range of 30 parts by weight.

In such a monomer mixture, the functional group of a monomer having a functional group suitable for introducing an ion-exchange group is a specific group derived from the aliphatic hydrocarbon-based monomer which is a matrix resin. When also contained in a copolymer of a monomer unit and a monomer unit based on a styrene-based monomer, specifically, a monomer having a functional group suitable for introducing the ion-exchange group When styrene is used as the body, on the other hand, when the unit based on the styrene-based monomer of the matrix resin is a unit based on styrene, etc., in the operation of introducing an ion exchange group into the membrane described below, the matrix resin is also used. The ion exchange group is introduced, and the durability of the obtained ion exchange membrane may be slightly reduced. Therefore, in such a case, styrene or various styrene nucleus substitutes are properly used as the styrene monomer, and an ion exchange group is hardly introduced into a unit based on the styrene monomer as a matrix resin. Is preferred.

The monomer mixture obtained as described above is adhered to a substrate and molded and polymerized. Here, as the substrate,
Conventionally used materials such as polyvinyl chloride, polyolefin and the like, which are conventionally used as base materials for ion exchange membranes, are used without any limitation. In order to obtain better durability as an ion exchange membrane, it is recommended to use a polyolefin substrate. As the base material made of polyolefin, a woven fabric made of polyethylene, polypropylene, polybutene, a copolymer thereof, a blend of these polymers, or the like is preferable. In addition, non-woven fabric, net,
Alternatively, those porous sheets and the like can be used without limitation. The single yarn of such a woven fabric may be either a monofilament or a multifilament. Also, the smaller the basis weight of the warp and the weft, the smaller the electrical resistance of the obtained ion exchange membrane can be. However, it is difficult to hold the woven fabric due to the yarn displacement, so that the number of the stitches per square inch is generally 10%.
The range of -500 is preferable. A woven fabric having a small number of stitches can be reduced to 1 by a method such as partial fusion at the intersection of single yarns.
A woven fabric having a small number of stitches can be used by fusing the polyethylene portion at the intersection with a composite filament having a core portion of polypropylene and a sheath portion of polyethylene, for example. The thickness of these substrates is not particularly limited, but is preferably in the range of 10 to 500 μm. In addition, calendering is performed on such a polyolefin substrate to improve the smoothness of the substrate surface by compressing the intersections of the warp and weft, or heat polymerization is performed by subjecting the substrate to heat treatment in advance. Processing such as suppression of dimensional change in the process may be performed. Furthermore, conventionally known surface treatment methods for polyolefin substrates such as corona discharge treatment and chlorosulfonic acid treatment,
It is recommended as a means to improve the adhesion between the base material and the ion exchange resin part.

When the monomer mixture is adhered to the above-mentioned base material and then subjected to molding polymerization, the temperature is generally raised from normal temperature under pressure, but the rate of temperature rise is not particularly limited. Instead, it may be appropriately selected. These polymerization conditions also depend on the type of polymerization initiator involved, the composition of the monomer mixture, and the type of base material, and cannot be determined unequivocally; It may be appropriately selected in consideration of mechanical properties. In addition, as a method of attaching the paste-like material to the cloth-like base material, a known method such as coating, impregnation, or dipping may be appropriately adopted.

The film-like polymer obtained by polymerization as described above may be converted, if necessary, into a known polymer such as sulfonate.
Chlorsulfonation, chloromethylation and amination, quaternary ammonium chlorination, quaternary pyridinium chlorination,
A desired ion exchange group can be introduced by a treatment such as phosphonium formation, sulfonium formation, or hydrolysis to form a cation exchange membrane or an anion exchange membrane. The introduction amount of these ion exchange groups is not particularly limited, but usually, the ion exchange capacity is preferably in the range of 0.1 to 20 meq / g-dry membrane, preferably 0.5 to 3 meq / g-dry membrane. is there. In addition, the thickness of the ion exchange membrane is a desired electric resistance,
It is also related to mechanical strength, transport number, durability, etc.
The range is preferably from 0 to 500 μm, preferably from 40 to 300 μm.

[0023]

According to the present invention, there is provided a method for producing an ion exchange membrane by a conventional paste method, wherein a monomer unit derived from an aliphatic hydrocarbon-based monomer and a copolymer is formed. By using a copolymer of a monomer unit having no unsaturated bond in the monomer unit and a unit based on a styrene-based monomer as the matrix resin, the matrix resin and the ion exchange resin or the base material Can significantly improve the adhesiveness of the resin, and can obtain an ion exchange membrane having extremely excellent durability especially against high temperatures, acids, alkalis and organic solvents.

The ion exchange membrane obtained by the present invention is extremely excellent in mechanical properties such as flexibility.
Furthermore, the electrical properties are also good, especially when a concentrated neutral salt, acid or alkali solution is subjected to electrodialysis or diffusion dialysis, or when used as a membrane for electrode reactions, and excellent properties in other systems using ion exchange membranes in general. Show.

[0025]

Hereinafter, Examples and Comparative Examples of the present invention will be described.
The present invention is not limited to these examples.

Example 1 70 parts by weight of 4-vinylpyridine, 5 parts by weight of styrene, 15 parts by weight of divinylbenzene, dicumyl peroxide 10 having a decomposition temperature of 117 ° C. for obtaining a half-life of 10 hours as a radical polymerization initiator A styrene-butadiene random copolymer having a styrene content of 30% by weight, a weight average molecular weight of 200,000, a hydrogenation rate of 98%, and hydrogenation as a part by weight and a matrix resin (trade name:
(Dynalon 1910P, manufactured by Nippon Synthetic Rubber) was added in an amount of 30 parts by weight to obtain a paste-like mixture.

Next, the above-mentioned paste-like mixture is applied to a calendered mesh made of high-density polyethylene and having a mesh number of 150 per square inch (trade name: Nip strong net, manufactured by NBC Industries, thickness: 150 μm), and polyester After coating the film as a release material, molding polymerization was performed by a paste method. The polymerization pattern was heated from 20 ° C. to 150 ° C. over 5 hours and kept at 150 ° C. for 5 hours. The thickness of the obtained film polymer was 150 μm.

Next, the obtained film-like polymer was treated with a methyl alcohol solution containing 50% by weight of methyl iodide,
A quaternization reaction of pyridine ring nitrogen at 16 ° C. for 16 hours,
It was further immersed in a 1N aqueous solution of sodium chloride at 30 ° C. for 1 hour to obtain a 170 μm thick anion exchange membrane. When the electric resistance of the obtained ion exchange membrane was measured in a 0.5 N aqueous solution of sodium chloride at 25 ° C., 6.9 Ω · c
m ² . When the ion exchange capacity was measured, it was 1.5 meq / g-dry membrane. Further, in order to evaluate the flexibility of the ion exchange membrane, a part of the ion exchange membrane was bent at an angle of 90 degrees, and the amount of water permeation under a pressure of 10 m water column was measured for the bent portion. Permeability was hardly observed.

Next, Nafion 324 manufactured by DuPont was simultaneously incorporated into a two-chamber electrodialyzer as the obtained anion exchange membrane and cation exchange membrane to concentrate nitric acid. The effective membrane area was 200 cm ² , and the initial concentration of the aqueous nitric acid solution was 0.1 N on both the lean side and the concentrated side. The operating conditions were a current density of 0.05 A / cm ² , a temperature of 80 ° C., and a solution flow rate of 10 liter / min. After the start of the operation, the concentration of the solution on the concentration side gradually increased, and reached 3.1 N after 3 hours. Thereafter, the concentration of the solution on the concentration side was kept at around 3.1N.

Six months after the operation was started, the operation of the electrodialysis apparatus was stopped, the electrodialysis apparatus was disassembled, and the state of the anion exchange membrane was observed. The appearance of the anion exchange membrane was not particularly changed.

When the ion exchange capacity of the anion exchange membrane in the portion where the current was supplied was measured, it was 1.5 meq / g-dry membrane, and the value was not changed from that before the electrodialysis.

Comparative Example 1 In Example 1, a styrene-butadiene rubber having a styrene content of 29% by weight and a weight average molecular weight of 200,000 (trade name: JSR-SL55) was used as a matrix resin.
7, manufactured by Nippon Synthetic Rubber Co., Ltd.) to obtain a 170 μm-thick anion exchange membrane in the same manner as in Example 1. The obtained anion exchange membrane has an electric resistance of 6.8 Ω · cm ^2.
And the ion exchange capacity was 1.5 meq / g-dry membrane. The flexibility of this anion exchange membrane was determined in Example 1.
When the evaluation was made in the same manner as in the above, almost no water permeation was recognized at the bent portion.

Next, nitric acid was concentrated by electrodialysis under the same conditions as in Example 1 except that the obtained anion exchange membrane was used. Six months after the operation was started, the operation of the electrodialysis device was stopped, the electrodialysis device was disassembled, and the state of the anion exchange membrane was observed. In the anion exchange membrane, a portion in which the ion exchange resin portion was missing from the base material to form a pinhole was observed.

When the ion exchange capacity of the energized portion of the anion exchange membrane was measured, the value was 1.1 meq.
/ G-dry film.

Example 2 70 parts by weight of chloromethylstyrene, 5 parts by weight of styrene,
Di-t having a decomposition temperature of 126 ° C. for obtaining a half-life of 10 hours as a radical polymerization initiator, 15 parts by weight of divinylbenzene having a purity of about 57%, 5 parts by weight of styrene oxide,
Hydrogenation of 15 parts by weight of tert-butyl peroxide and a matrix resin having a styrene content of 20% by weight and a weight average molecular weight of 200,000 (hydrogenation ratio 99%)
Styrene-isoprene triblock copolymer (trade name:
15 parts by weight of Septon 2005 (manufactured by Kuraray) were added to obtain a paste-like mixture. Then, using this paste-like mixture, a film-like polymer having a thickness of 152 μm was obtained in the same manner as in Example 1.

Then, the obtained membrane polymer was subjected to an amination reaction at 30 ° C. for 16 hours using an aqueous solution of 10% by weight of trimethylamine and 20% by weight of acetone to obtain an anion exchange membrane having a thickness of 170 μm. Was. The obtained anion exchange membrane had an electrical resistance of 3.7 Ω · cm ² and an ion exchange capacity of 1.8 meq / g-dry membrane. Also,
When the flexibility of the anion exchange membrane was evaluated in the same manner as in Example 1, almost no water permeation was observed at the bent portion.

Next, electrodialysis was performed in the same manner as in Example 1 except that the obtained anion exchange membrane was used, sodium hydroxide was used instead of nitric acid, and the current density was operated at 0.1 A / cm ^2. The alkali was concentrated. The concentration increase on the concentration side after the start of operation reached 3.5 N after 3 hours, and thereafter, the concentration of the solution on the concentration side was kept near this value.

Six months after the operation was started, the operation of the electrodialysis apparatus was stopped, the electrodialysis apparatus was disassembled, and the state of the anion exchange membrane was observed. The appearance of the anion exchange membrane was not particularly changed.

When the ion exchange capacity of the anion exchange membrane in the portion where the current was supplied was measured, it was 1.7 meq / g-dry membrane, and there was almost no change in the value before the electrodialysis.

Comparative Example 2 An anion exchange membrane having a thickness of 170 μm was obtained in the same manner as in Example 2 except that polystyrene having a weight average molecular weight of 200,000 was used as the matrix resin. . The obtained anion exchange membrane has an electric resistance of 3.8 Ω · cm ² and an ion exchange capacity of 1.8.
meq / g-a dry film. When the flexibility of this anion exchange membrane was evaluated in the same manner as in Example 1, the water permeability of the bent portion was 5.4 ml / hr. cm ² .
atm.

Next, nitric acid was concentrated by electrodialysis under the same conditions as in Example 1 except that the obtained anion exchange membrane was used. Six months after the operation was started, the operation of the electrodialysis device was stopped, the electrodialysis device was disassembled, and the state of the anion exchange membrane was observed. In the anion exchange membrane, a portion in which the ion exchange resin portion was missing from the base material to form a pinhole was observed.

When the ion exchange capacity of the energized portion of the anion exchange membrane was measured, the value was 1.5 meq.
/ G-dry film.

Example 3 70 parts by weight of chloromethylstyrene, 5 parts by weight of styrene,
5 parts by weight of styrene oxide, 15 parts by weight of divinylbenzene, 5 parts by weight of benzoyl peroxide having a decomposition temperature of 74 ° C. for obtaining a half-life of 10 hours as a radical polymerization initiator, and 40% by weight of polystyrene as a matrix resin. Hydrogenated (hydrogenated 99%) styrene-butadi entry block copolymer having a weight average molecular weight of 150,000 (trade name: Tuftec 105)
1, Asahi Kasei) was added to obtain a paste-like mixture.

Next, the thickness of polyvinyl chloride is 100 μm.
After the above-mentioned paste-like mixture was applied to a woven fabric having a thickness of m and covered with a polyester film as a release material, molding polymerization was performed by a paste method. Polymerization pattern is 20 ° C
To 70 ° C. over 2 hours and kept at 70 ° C. for 5 hours. The thickness of the obtained film polymer was 100 μm.

Next, the obtained film-like polymer was used in Example 2.
Amination was carried out in the same manner as in the above to obtain an anion exchange membrane having a thickness of 120 μm. The obtained ion exchange membrane has an electric resistance of 4.9 Ω · cm ² and an ion exchange capacity of 1.3 me.
q / g-a dry film. When the flexibility of the anion exchange membrane was evaluated in the same manner as in Example 1, almost no water permeation was observed at the bent portion.

Next, nitric acid was concentrated by electrodialysis under the same conditions as in Example 1 except that the obtained anion exchange membrane was used. Twelve months after the operation was started, the operation of the electrodialysis device was stopped, the electrodialysis device was disassembled, and the state of the anion exchange membrane was observed. The appearance of the anion exchange membrane was not particularly changed.

When the ion exchange capacity of the anion exchange membrane in the portion where the current was supplied was measured, the membrane was 1.3 meq / g-dry membrane, and the value was not changed from that before electrodialysis.

Example 4 65 parts by weight of 4-vinylpyridine, 15 parts by weight of styrene,
15 parts by weight of divinylbenzene, 13 parts by weight of tert-butyl hydroperoxide having a decomposition temperature of 167 ° C. for obtaining a half-life of 10 hours as a radical polymerization initiator, and a polystyrene content of 50 as a matrix resin.
% By weight, the content of each of polyethylene and polypropylene was 25% by weight, and the weight average molecular weight was 300,00.
20 parts by weight of a styrene-ethylene-propylene block copolymer, which is 0, was added to obtain a paste-like mixture. Then, using this paste-like mixture, an anion exchange membrane having a thickness of 170 μm was obtained in the same manner as in Example 1.

The obtained ion exchange membrane has an electric resistance of 5.
9 Ω · cm ² and an ion exchange capacity of 1.6 meq /
g-dry film. When the flexibility of the anion exchange membrane was evaluated in the same manner as in Example 1, almost no water permeation was observed at the bent portion.

Next, the obtained anion exchange membrane was incorporated into a two-chamber electrodialysis apparatus similar to that used in Example 1, and hydrochloric acid was concentrated in an aqueous solution containing 10% by weight of dioxane. Was. The effective membrane area was 200 cm ² , and the initial hydrochloric acid aqueous solution concentration was 0.1 N on both the lean side and the concentrated side. The operating conditions were a current density of 0.1 A / cm ² , a temperature of 50 ° C., and a solution flow rate of 10 liter / min. After the start of the operation, the concentration of the solution on the concentration side gradually increased, and reached 2.9 N after 3 hours. Thereafter, the solution concentration on the concentration side was 2.9.
It was kept near N.

Twelve months after the start of operation, the operation of the electrodialysis apparatus was stopped, the electrodialysis apparatus was disassembled, and the state of the anion exchange membrane was observed. The appearance of the anion exchange membrane was not particularly changed.

When the ion exchange capacity of the anion exchange membrane at the portion where the current was supplied was measured, it was 1.6 meq / g-dry membrane, and the value was not changed from that before electrodialysis.

Claims (1)

(57) [Claims] 1. A monomer unit derived from a monomer having a functional group or an ion exchange group suitable for introducing an ion exchange group, a crosslinking agent, a polymerization initiator and an aliphatic hydrocarbon monomer. In a state where the copolymer is constituted, a mixture comprising a copolymer of a monomer unit having no unsaturated bond in the monomer unit and a monomer unit based on a styrene-based monomer,
A method for producing an ion-exchange membrane, which comprises introducing an ion-exchange group as needed after adhering to a substrate and subjecting it to polymerization.