JPH0443098B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion exchanger containing an oxidatively polymerizable monomer, which is characterized in that the monomer is oxidatively polymerized. Relating to a manufacturing method.

[Prior art and its problems]

Conventionally, various methods have been attempted to improve or reduce the ion-selective permselectivity of ion exchange membranes, or to change the permselectivity between ions of the same sign. Furthermore, various attempts have been made to impart new functions to ion exchange membranes by impregnating and polymerizing polymerizable vinyl monomers into cation exchange membranes or anion exchange membranes. This has led to a decrease in the amount of acid, an increase in the transfer number, a decrease in the amount of acid leakage, and a decrease in the amount of base leakage. However, these methods generally polymerize vinyl monomers within the membrane, and the ion exchange membrane itself may swell with these vinyl monomers.
There is a problem in that the mechanical strength of the membrane decreases. Also,
Although it has been reported that condensation monomers are condensed within an ion exchange membrane, heat treatment is often required to complete the condensation reaction, resulting in problems that impair membrane performance.

[Means for solving problems]

In view of the above problems, the present inventors generally form a matrix of another polymer in the matrix of an ion exchanger to change the properties of the ion exchanger and to add new functions to the ion exchanger. We have repeatedly considered whether it would be possible to provide an endowment. As a result, oxidatively polymerizable heterocyclic compounds, such as pyrrole, thiophene, and their derivatives, have good affinity for ion exchangers and are relatively easily polymerized within the membrane by oxidation reactions, allowing the ion The inventors have discovered that the characteristics of the exchanger can be changed and that an ion exchanger having new useful functions can be obtained, leading to the provision of the present invention. That is, according to the present invention, there is provided a method for producing an ion exchanger, which comprises oxidatively polymerizing an oxidatively polymerizable monomer in an ion exchanger containing the monomer.

The ion exchangers of the present invention are not limited to organic ones, but also inorganic ion exchangers themselves such as zirconium phosphate, and those obtained by pressurizing and heat-molding these with suitable organic or inorganic binders are also suitable. used for. Examples of organic ion exchangers include polymeric ion exchangers, so-called styrene-divinylbenzene copolymers with ion exchange groups bonded to them, and condensation ion exchangers with cation exchange groups and/or anions. Those to which an ion exchange group is bonded are preferably used. As such an ion exchanger, conventionally known homogeneous or heterogeneous ion exchangers can be used, and the substrate of the ion exchanger may be hydrocarbon-based, carbon fluoride-based, or perfluorocarbon-based. It is preferably used without any restrictions.

The above-mentioned ion exchanger used in the present invention is not particularly limited as long as it generally has 0.1 milliequivalent or more and 15 milliequivalent or less of exchange groups per 1 g of the dry ion exchanger. As the ion exchange group, conventionally known cation exchange groups such as sulfonic acid, carboxylic acid, phosphoric acid, phosphorous acid, sulfonic acid ester, phenolic hydroxyl group, thiol group, tertiary perfluoroalcohol, etc. are used. As the anion exchange group, onium bases such as primary, secondary, and tertiary amines, quaternary ammonium, tertiary sulfonium, quaternary phosphonium, and cobaltyranium are suitable.

In addition, various types of ion exchange groups according to the present invention are suitable as required, such as those in which the ion exchange groups are uniformly dispersed in the substrate, those in which the ion exchange groups are present concentrated on one side, and those in which a concentration gradient exists. used for. The ion exchange groups present in such an ion exchanger include cases where only a cation exchange group is present, cases where only an anion exchange group is present, and cases where both ion exchange groups are present simultaneously. When both ion exchange groups are present at the same time, the two types of ion exchange groups may be present in a layered form over two or more layers, or arbitrarily uniformly present. In addition, there is a layer in which cation exchange groups exist, a layer in which cation exchange groups and anion exchange groups are arbitrarily distributed, and a layer in which cation exchange groups exist, or an anion exchange group. Various ion exchangers are formed depending on the state of existence of various ion exchange groups, such as when there is a layer or vice versa, but all of these forms of ion exchangers are
Each is effectively applied in the method of the present invention. Note that the above-mentioned cation exchange group and anion exchange group do not mean the same type of cation exchange group and anion exchange group, but different cation exchange groups such as a carboxylic acid group and a sulfonic acid group. However, it is often particularly effective when different types are used. Furthermore, the above-mentioned inorganic ion exchanger and organic ion exchanger are not limited to a single matrix, but a composite of the two may also be suitably used. Specifically, fine powder of an inorganic ion exchanger is molded into an appropriate shape using a thermoplastic organic ion exchanger, or a polymer electrolyte or an inert polymer is dissolved in an appropriate solvent. However, by dispersing an inorganic ion exchanger therein and scattering the solvent, an ion exchanger having a desired shape can be obtained.
Furthermore, the ion exchanger used in the present invention may be in various shapes such as granular, powder, fibrous, and tubular materials in addition to membrane-like materials.

In the present invention, the oxidatively polymerizable monomer contained in the above-mentioned ion exchanger includes pyrrole and its derivatives, such as N-methylpyrrole, 2
- Ethylpyrrole, etc., thiophene and its derivatives, isothianaphthene and its derivatives, indole, azulene, furan, aniline, phenol,
One or more derivatives of benzene, naphthalene, etc. are preferably used. In particular, heterocyclic compounds such as pyrrole, indole, azulene, thiophene, furan, and their derivatives have good affinity with ion exchangers and are preferably used because they undergo ion exchange and are uniformly dispersed in the ion exchanger. The method of incorporating these oxidatively polymerizable monomers into an ion exchanger generally involves adding the monomers to a solution of water or an organic solvent such as alcohol or acetonitrile to an appropriate concentration of 0.01% to saturation. A method of immersing the ion exchanger is easily adopted. The immersion time varies depending on the type of oxidatively polymerizable monomer and the type of ion exchanger used, and can be generally selected from an appropriate time of 1 minute or more and up to 72 hours.

Next, in the present invention, the desired ion exchanger can be easily obtained by oxidatively polymerizing the oxidatively polymerizable monomer contained in the above-mentioned ion exchanger. Oxidative polymerization in the present invention can generally be easily achieved by immersing an ion exchanger containing an oxidatively polymerizable monomer in a solution such as an aqueous solution of an oxidizing agent. As the oxidizing agent, conventionally known oxidizing agents are appropriately used, such as H ₂ O ₂ ,
Peroxides such _as ( _C6H5CO ) _{2O2 , FeCl3} , _CuSO4 ,
Metal salts such as CuCl ₂ and RuCl ₃ , Na ₂ S ₂ O ₈ , Na ₂
Puroxo acids (salts) such as SO ₅ , (NH ₄ ) ₂ SO ₅ ,
Examples include oxyacid salts such as NaClO, NaBrO, and _NaClO3 . In other words, metal ions whose charge changes by redox, such as trivalent iron ions, divalent copper ions, and trivalent ruthenium ions, as well as organic compounds or metal complex cations whose charge changes by redox. Cations such as ions, and oxidizing anions such as persulfate ions, perborate ions, and perchlorate ions are preferably used. These cations and anions are suitable because they undergo ion exchange with the exchange groups of the ion exchanger in an oxidized state and are uniformly dispersed within the ion exchanger. Note that when it is desired to carry out the oxidative polymerization reaction of the present invention only in the surface layer of the ion exchanger, a peracid or a naphthalene ring bonded with a long-chain alkyl group cannot easily enter the pores of the ion exchanger. It is preferable to use a compound in which a peracid group is bonded to such a compound.

Some specific examples of the present invention will be shown below.

(1) When a cation exchange membrane crosslinked with styrene-divinylbenzene is immersed in an aqueous solution of pyrrole and then immersed in an aqueous solution of iron chloride, the pyrrole polymerizes. The membrane thus obtained was thoroughly washed with water, thoroughly conditioned with 1N hydrochloric acid and 0.5N saline to remove Fe ⁶⁺ , and then treated with 0.25N hydrochloric acid and 0.25N saline. When a solution containing hydrogen is subjected to electrodialysis, hydrogen ions selectively permeate through the membrane.

(2) When the electrical conductivity of the film synthesized in (1) was measured after drying under reduced pressure, it was found to have an electrical resistance of 1 KΩ·cm ² or less. On the other hand, the membrane in which pyrrole is not polymerized has an electrical conductivity of 20 MΩ·cm ² or more.

(3) An anion exchange resin having a pyridium base as an anion exchange group was immersed in an aqueous solution of pyrrole, and then immersed in an ammonium persulfate solution for polymerization. The resin did not dissolve even after repeated washing with acid and alkali.

(4) When a tubular ion exchanger having benzyltrimethylammonium ion as an anion exchange group was immersed in an aqueous solution of aniline and then in an aqueous ammonium persulfate solution, aniline impregnated and polymerized into the anion exchanger, resulting in a pale ion exchanger. The yellow tubular anion exchanger turned black. When the electrical conductivity of this was measured, it was found to be less than 100 Ω·cm, whereas the ion exchanger not impregnated with aniline had an electrical conductivity of more than 20 MΩ·cm.

(5) A pyridinium base type membrane anion exchanger was immersed in an aqueous aniline solution, and then immersed in an aqueous ammonium persulfate solution, resulting in polymerization to form black polyaniline. When the membrane-like material was taken out and the selective permeability of sulfate ions and chloride ions was measured, it was found that when polyaniline was not present, when 1 equivalent of chlorine ions permeated, 0.3 equivalents of sulfate ions permeated. , and those impregnated with polyaniline were 0.01.

〔Effect of the invention〕

The ion exchanger obtained in the present invention has different ion permeability, especially selective permeability between ions of the same sign,
In general, the permeation of highly charged ionic species and ionic species with a small hydrated ion radius is blocked.
Furthermore, depending on the method of oxidative polymerization of monomers, an electron conductive function can be imparted to the ion exchange membrane, turning it into a new functional substance such as a sensor.

〔Example〕

EXAMPLES Hereinafter, the content of the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 Ion exchange capacity with sulfonic acid group bonded is 2.3
milliequivalent/gram dry membrane cation exchange membrane (7.0×
7.0 cm ² ) was immersed in 500 c.c. of a 2% aqueous solution of pyrrole to achieve equilibrium, then immersed in a 5% aqueous solution of ferric chloride and stirred. After leaving it for 16 hours, I took it out, washed it with water, washed it with ethanol, immersed it in 1N hydrochloric acid, changed the hydrochloric acid repeatedly, and looked at the absorption of iron using fluorescent X-rays. Iron had been removed from

Using the membrane obtained above, an acrylic cell was divided into two chambers, each having an internal volume of 120 c.c., and filled with 0.25N NaCl and 0.25N CaCl ₂ solutions. The membrane was sufficiently equilibrated with this solution of 0.25N NaCl and 0.25N CaCl ₂ before being incorporated into the two-chamber cell. This cell was equipped with silver and silver chloride electrodes in both chambers, and electrodialysis was carried out through these electrodes at a current density of 1 A/dm ² . The effective current carrying area was 0.1 ^dm2 . 2
When the amount of cations permeated through the membrane after electricity was applied for a certain period of time was determined, the current efficiency was 97%, and when 1 equivalent of Na ⁺ permeated through the membrane, the amount of Ca ²⁺ permeated through the membrane was 0.2 equivalent.

On the other hand, for comparison, an ordinary sulfonic acid type cation exchange membrane impregnated with pyrrole and not polymerized was used for electrodialysis under the same conditions as above, and the current efficiency measured was 98%, indicating that Na ⁺ When 1 equivalent of Ca ²⁺ passed through the membrane, 2.1 equivalents of Ca 2+ passed through the membrane.

Further, the electrodialyzed pyrrole impregnated polymer membrane was taken out, equilibrated with 1N-hydrochloric acid, dried under reduced pressure, and then the electrical conductivity was measured and found to be 28 Ω·cm. On the other hand, an ordinary cation exchange membrane that was not impregnated with pyrrole and polymerized had an electrical conductivity of 20 MΩ·cm or more when measured under the same conditions. The cation exchange membrane used was made by copolymerizing styrene and divinylbenzene.
The content of divinylbenzene was 5%. Further, the electrical conductivity was measured by applying silver paste on a film with a width of 1 cm with a gap of 1 cm, drying it, measuring it with a conductivity meter, and calculating the specific electrical conductivity by converting it to the thickness of the film. The same thing was done in the following examples.

Example 2 Polyvinyl chloride fine powder was added to a mixture of styrene, divinylbenzene and 4-vinylpyridine, and then benzoyl peroxide as a polymerization initiator was added to form a viscous paste mixture, which was then made into polyvinyl chloride. The mixture was coated on a cloth, both sides covered with cellophane, and polymerized by heating at 70°C in a nitrogen atmosphere to obtain a polymer film. This was placed in an alkylation bath consisting of a mixed solution of hexane and methyl iodide at 25°C.
An anion exchange membrane having a quaternary ammonium base as an anion exchange group was obtained.

The anion exchange membrane obtained above was sufficiently immersed in an aqueous solution in which 5% aniline was dispersed, then immersed in a 10% aqueous solution of ammonium persulfate, and then heated at room temperature for 60 minutes.
Stir for hours. The film-like substance turned pale yellow to black.

After taking this out and conditioning it with 1N hydrochloric acid and 0.5N ammonia water, a 1:1 mixed solution of 0.25N sodium sulfate and 0.25N table salt was used for electrodialysis in the same manner as in Example 1. _SO4-- ^{and Cl-}
The membrane permeability of the two was compared. As a result, the membrane impregnated with aniline and not polymerized has a permeation rate of 1 equivalent of Cl ^-
Although 0.3 equivalents of SO ₄ ^-- permeated through the membrane, only 0.01 equivalents permeated through the membrane in which aniline was polymerized within the membrane.

In addition, after drying the aniline-impregnated and polymerized anion exchange membrane after electrodialysis described above under reduced pressure,
When the conductivity was measured, it was 12Ω·cm.

Example 3 Benzoyl peroxide was added to a paste mixture obtained by adding fine powder of polyvinyl chloride to a mixture of styrene, 4-vinylpyridine, and divinylbenzene, and this was applied to a polypropylene nonwoven fabric and heated. It was polymerized to form a film. this
It was immersed in 97% sulfuric acid and gently sulfonated for 3 days. Next, this was once immersed in 0.1N caustic soda and then immersed in a bath consisting of hexane and methyl iodide to alkylate the pyridine ring. The thus obtained amphoteric ion exchange membrane had a cation exchange capacity of 0.81 meq/g dry and an anion exchange capacity of 1.12 meq/g dry.

The following two treatments were performed using this amphoteric ion exchange membrane.

(a) When the membrane was immersed in a 2% aqueous pyrrole solution and then in an aqueous solution of ruthenium trichloride, pyrrole impregnated and polymerized in the amphoteric ion exchange membrane. After washing with water and methanol, it was dried under reduced pressure and its conductivity was measured to be 25 Ω·cm.

(b) immersed in a 1% aqueous solution of aniline and then immersed in a 5% aqueous solution of sodium persulfate to polymerize;
When this was washed with water and methanol and then dried under reduced pressure, it showed an electrical conductivity of 19Ω·cm.

Furthermore, when both membranes were electrodialyzed with a 1:1 mixed solution of 0.25N hydrochloric acid and 0.25N common salt, the membrane impregnated with pyrrole had a current efficiency of 95.
%, 21 equivalents of hydrogen ions per 1 equivalent of Na ⁺ permeated the membrane.

Furthermore, the membrane impregnated with polyaniline had a current efficiency of 97%, and 30 equivalents of hydrogen ions per 1 equivalent of Na ⁺ permeated.

Example 4 A block copolymer was synthesized by living anionic polymerization of styrene, butadiene and N,N'-dimethylvinylbenzylamine. When this was casted on a flat plate to form a film and observed under an electron microscope, a phase-separated structure was formed. That is, it was divided into a styrene region, a butadiene region, and an N,N'-dimethylvinylbenzylamine region. This film was sulfonated with sulfuric acid to introduce a sulfonic acid group, then substituted with methanol, and then treated with methyl iodide to introduce a quaternary ammonium base.

The thus obtained membrane in which cation exchanger regions, neutral regions, and anion exchanger regions are distributed in a mosaic pattern is immersed in a 2% solution of pyrrole in acetonitrile, and then in an aqueous solution of iron trichloride. When immersed in water, pyrrole was oxidatively polymerized mainly in the region where sulfonic acid groups were present.

When we measured the permeability of this membrane to table salt and recommended sugar, we found that the membrane impregnated with pyrrole and not subjected to oxidative polymerization had a permeability coefficient of recommended sugar of 1/81 compared to that of table salt, but it was 1/210. It was decreasing.

Furthermore, when another membrane made in the same way was washed with water and methanol and dried under reduced pressure, its conductivity was measured, and it was found that it was conductive in the thickness direction, but not at all in the two-dimensional direction of the membrane. There was no degree. In other words, it was an anisotropically conductive film.

Example 5 Fine powder of polyethylene is mixed with a mixture of styrene and divinylbenzene to make a viscous paste-like mixture, and this is applied to a polypropylene cloth. Only one side was sulfonated with concentrated sulfuric acid to introduce sulfonic acid groups.

Next, this was immersed in a 10% ethyl alcohol solution of pyrrole for 16 hours, and then immersed in a 5% aqueous solution of ruthenium trichloride, whereupon only the pyrrole in the sulfonic acid group was oxidatively polymerized.

After washing it with water, washing it with methanol, and drying it under reduced pressure, its conductivity was measured, and it was found that only one side of the membrane was conductive in two-dimensional directions, and the back side was an insulator.

Example 6 The membrane that had been sulfonated on only one side in Example 5 was again incorporated into a reaction device capable of reacting on only one side, and the unreacted side was brought into contact with a carbon tetrachloride solution of chloromethyl ether and tin tetrachloride to remove chloromethyl groups. introduced on one side of the membrane. Next, this membrane was immersed in a water-acetone solution of trimethylamine to perform an amination reaction, so that one side of the membrane had a sulfonic acid group and the other side had a quaternary group.
We created a membrane with grade ammonium base.

This membrane was immersed in a 5% aniline solution in ethanol and then in a 5% aqueous solution of sodium persulfate. After 10 hours, aniline had been polymerized at the anion exchange group. This part was found to be electrically conductive.

Next, when this membrane was immersed in a 2% ethanol solution of pyrrole and then in a 5% aqueous solution of ferric chloride, pyrrole polymerized in the areas where cation exchange groups were present, and was washed with water and depressurized. When the conductivity was measured after drying, conductivity was also observed on this surface.

Example 7 Commercially available cation exchange resins, anion exchange resins, and amphoteric ion exchange resins were each subjected to the following treatments.

(a) When a sulfonic acid type cation exchange resin was immersed in a 10% pyrrole aqueous solution and then immersed in a ferric chloride aqueous solution, the cation exchange resin turned black.

(b) When a resin having a quaternary ammonium base type anion exchange group was immersed in a 10% aqueous solution of pyrrole and then in a 10% aqueous solution of ammonium persulfate, it became a black spherical resin.

(c) A spherical amphoteric ion exchange resin containing a quaternary ammonium base and a sulfonic acid group is
% aqueous solution, then 5% of ferric chloride.
When immersed in an aqueous solution, the spherical resin similarly turned black and pyrrole was oxidatively polymerized.

The resins obtained in (a), (b), and (c) above were all found to have electrical conductivity after being dried under reduced pressure.

Example 8 Polychloromethylstyrene was extruded from a nozzle to obtain a tubular polymer. This was contacted with a solution of aluminum chloride in carbon disulfide to form a crosslinking reaction via a Friedel-Crafts reaction. Next, this was immersed in a mixed solution of trimethylamine, water, and acetone for amination treatment to obtain a tubular anion exchanger having a quaternary ammonium base.

This was immersed in an aqueous solution of pyrrole and then in an aqueous ammonium persulfate solution to obtain a tubular material of the present invention. As a result of measuring the electrical conductivity of this material, no electrical conductivity was observed in the material in which pyrrole was not polymerized, but electrical conductivity was observed in the material in which pyrrole was polymerized.

Example 9 A fine powder of a cation exchange resin obtained by sulfonating a copolymer of styrene and divinylbenzene was mixed with polystyrene and extruded from a nozzle in the same manner as in Example 8 to form a tubular cation exchanger. Synthesized.

After boiling this with pure water, thiol 2
% aqueous solution, then immersed in an aqueous solution of iron trichloride, heated to 50°C, and left for 24 hours. Next, this tubular ion exchanger was taken out, washed with water, dried under reduced pressure, and its electrical conductivity was measured, and it was found to have electrical conductivity.

Claims (1)

[Claims] 1. A method for producing an ion exchanger, which comprises oxidatively polymerizing an oxidatively polymerizable monomer in an ionexchanger containing a monomer capable of oxidatively polymerizing.