JPH0443097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing an ion exchanger in which an oxidatively polymerizable monomer is polymerized in an ion exchanger containing an oxidizing agent.

(Prior Art and Problems) Conventionally, various methods have been attempted in order to improve or reduce the selective ion permeability as a function of an ion exchange membrane, or to change the selective permeability between ions of the same sign. In addition, 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 be swollen by these vinyl monomers, resulting in a decrease in the mechanical strength of the membrane. There are problems that arise.
It has also been reported that condensation monomers can be condensed within an ion exchange membrane, but this often requires heat treatment to complete the condensation reaction.
Problems arise that impair the performance of the membrane.

(Means for Solving the Problems) In view of the above, the present inventors generally change the properties of an ion exchanger by forming a matrix of another polymer in the matrix of the ion exchanger, and Various studies have been conducted to see if it is possible to impart new functions to the ion exchanger. As a result, heterocyclic compounds such as pyrrole and its derivatives, thiophene and its derivatives have good affinity for ion exchangers, and are relatively easily polymerized within the membrane by oxidation reaction, resulting in the formation of ion exchangers. The present invention was developed based on the discovery that an ion exchanger with different properties and new useful functions can be obtained. That is, according to the present invention,
A method for producing an ion exchanger is provided, which comprises polymerizing an oxidatively polymerizable monomer in an ion exchanger containing an oxidizing agent.

The ion exchangers of the present invention are not limited to organic ion exchangers, but include inorganic ion exchangers themselves such as zirconium phosphate, and those obtained by pressurizing and heat molding these with suitable organic or inorganic binders. is also suitably used. An example of an organic ion exchanger is a polymeric ion exchanger, so-called styrene.
Divinylbenzene-based copolymers to which ion exchange groups are bonded, and ion exchangers such as condensed ion exchangers to which cation exchange groups and/or anion exchange groups are 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. Suitable for use regardless of the type of item.

In addition, the ion exchanger used in the present invention generally has a
It is not particularly limited as long as it has 15 milliequivalents of ion exchange group bonded thereto. 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, and tertiary perfluoroalcohol are used. Anion exchange groups include primary, secondary, and tertiary amines,
Onium bases such as quaternary ammonium, tertiary sulfonium, quaternary phosphonium, cobaltyranium and the like are preferred.

In addition, as the above-mentioned ion exchangers, various types of ion exchangers such as those in which the ion exchange groups are uniformly dispersed in the substrate, those in which the ion exchange groups are present biased to one side, and those in which there is a concentration gradient are suitable as required. 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 present at the same time, the two types of ion exchange groups may exist in a layered form over two or more layers, or may exist arbitrarily uniformly. 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 then there is another layer in which cation exchange groups exist, or Various types of ion exchangers are formed depending on the state of existence of various ion exchange groups, such as when there is a layer containing a layer containing a ion exchanger, or vice versa. Effectively applied in the method of 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. Further, the above-mentioned inorganic ion exchanger and organic ion exchanger are not limited to a single matrix, but a composite of both 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. 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, improved and useful ion exchangers can be obtained by using the various ion exchangers described above and selecting the oxidizing agent and oxidatively polymerizable monomer described below. . A schematic aspect thereof will be described below. for example,
(1) By using a cationic oxidizing agent for the anion exchanger and an anionic oxidizing agent for the cation exchanger, each takes advantage of the fact that it is difficult to uniformly contain the oxidizing agent in the ion exchanger. As a result, monomers that can be oxidatively polymerized only on one side can be easily polymerized.
An ion exchanger with an asymmetric structure can be obtained.
(2) On the other hand, when using an amphoteric ion exchanger, both cationic and anionic oxidizing agents are uniformly contained, so monomers that can be oxidatively polymerized are polymerized to form a uniform structure. ion exchanger can be easily obtained. (3) When using a bipolar type ion exchange membrane, since a monomer that can be oxidatively polymerized can be polymerized on only one side, it is possible to form a membrane with alternating conductive layers and insulating layers. It is possible to obtain substances. (4) When using a hydrocarbon-based ion exchanger with a crosslinked structure, the impregnation rate and amount of the oxidatively polymerizable monomer can be easily controlled, so the mechanical strength of the resulting ion exchanger can be improved. It has the advantage of being easy to hold. In particular, when an ion exchanger having a crosslinked structure and a reinforcing material is used, an ion exchanger having higher mechanical strength can be obtained.

In the present invention, the oxidizing agent to be present in the ion exchanger is not particularly limited as long as it is a conventionally known oxidizing agent. _For example, peroxides such as _{H2O2 ,} ( _C6H5CO ) _{2O2 ,} metal salts such _{as FeCl3} , _CuSO4 , _CuCl2 , _{RuCl3 , Na2S2O8 , Na2SO5} , (NH ₄ ) ₂ SO ₅ and other peroxo acids (salts), NaClO, NaBrO,
Examples include oxyacid salts such as _NaClO3 . In other words, metal ions whose charge changes by redox, such as trivalent iron ions, divalent copper ions, and trivalent ruthenium ions, and organic compounds or metal complex ions whose charge changes by redox. Cations such as ions, and oxidizing anions such as persulfate 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 bonded with a long-chain alkyl group or a naphthalene ring that can easily enter the pores of the ion exchanger. It is possible to use a compound in which a peracid group is bonded to a compound that does not have a peracid group.

In the present invention, oxidatively polymerizable monomers used include, for example, pyrrole and its derivatives such as N-methylpyrrole and 2-ethylpyrrole, thiophene and its derivatives, isothianactene and its derivatives, indole, azulene, furan, aniline, etc. , phenol, benzene, naphthalene and other derivatives. In particular, heterocyclic compounds such as pyrrole, indole, azulene, thiophene, furan and their derivatives are
It has good affinity for ion exchangers and is easily oxidatively polymerized to the ion exchangers, so it is suitably used.

The method of oxidative polymerization in the present invention is not particularly limited, and generally, ion exchange containing an oxidizing agent is carried out using an organic solvent such as acetonitrile, ethyl alcohol,
Alternatively, it may be immersed in an inorganic solvent such as water in which a monomer capable of oxidative polymerization is dissolved or dispersed. The immersion is carried out under cooling to the extent that the solvent does not freeze, or under heating to the extent that the solvent does not boil. Further, in the polymerization, the concentration of the monomer is not particularly limited and may range from 0.01% to a saturated solution of the monomer, and the polymerization may be carried out in a suspended state. The polymerization time varies depending on the type of monomer and the type of ion exchanger, and can be carried out by selecting an appropriate time generally from 1 minute to 72 hours.

(Actions and Effects of the Invention) The ion exchanger obtained by the present invention has a change in 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, electron conductivity can be imparted to the ion exchange membrane, turning it into a new functional substance such as a sensor.

Some specific examples are shown below.

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

(2) After drying the film-like material synthesized in (1) under reduced pressure, the electrical conductivity was measured, and the electrical resistance was 1 kΩ-cm ² or less. On the other hand, the membrane in which pyrrole was not polymerized had an electrical resistance of 20 MΩ-cm ² or more.

(3) When an anion exchange resin containing a pyridinium base as an anion exchange group was equilibrated in an ammonium persulfate solution to form a persulfate ion form and then immersed in an aqueous solution of pyrrole, pyrrole was selected as an anion exchange membrane. Polymerization was performed by adsorbed ion exchange. The pale yellow spherical resin turned black, but the acid,
No elution occurred even after repeated washing with alkali.

(4) A tubular ion exchanger with benzyltrimethylammonium ions as anion exchange groups was equilibrated in an ammonium persulfate solution to form a persulfate ion type, and then immersed in an aniline aqueous solution, whereupon aniline exchanged anions. The pale yellow tubular anion exchanger changed color to black due to impregnation polymerization in the body. When we measured the electrical conductivity of this, it showed an electrical resistance of less than 100Ω- ^cm2 , but the ion exchanger not impregnated with aniline had a resistance of 20MΩ.
There was an electrical resistance of -cm ² or more.

(5) When a pyridinium base type membrane anion exchanger was immersed in an aqueous ammonium persulfate solution and the anion exchange groups exchanged persulfate ions, aniline was added and polymerized. It polymerized in the liquid phase to form black polyaniline, and at the same time, it was impregnated into the film-like material and polymerized. When the film-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, chloride ions were
When an equivalent amount of sulfate ions permeated, 0.3 equivalents of sulfate ions permeated, whereas 0.01 equivalents of sulfate ions permeated through the polyaniline impregnation.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Ion exchange capacity with sulfonic acid group bonded is 2.3
Milliequivalents/g dry membrane cation exchange membrane (7.0
×7.0cm ² ) in a 5% aqueous solution of ferric chloride,
It was equilibrated and made into ferric ion form. Next, it was immersed in 500 c.c. of a 2% aqueous solution of pyrrole and stirred. 16
After standing for a while, it was taken out, washed with water, washed with ethanol, immersed in 1N hydrochloric acid, and the hydrochloric acid was replaced repeatedly. When iron absorption was observed using fluorescent X-rays, it was found that most of the iron had been removed from the film.

An acrylic cell was divided into two chambers using the membrane obtained above, and each chamber with an internal volume of 120 c.c. was filled with a solution of 0.25N NaCl and 0.25N CaCl ₂ . In addition, before incorporating the membrane into a two-chamber cell, this
A solution of 0.25N NaCl and 0.25N CaCl ₂ was fully equilibrated. 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 . When the amount of cations that permeated the membrane after 2 hours of current was applied, the current efficiency was 97%, and the amount of Ca ²⁺ that permeated the membrane when 1 equivalent of Na ⁺ permeated the membrane was
It was 0.2 equivalent.

On the other hand, for comparison, electrodialysis was performed under the same conditions as above using a normal sulfonic acid type cation exchange membrane that was not impregnated with pyrrole and polymerized, and the current efficiency was 98%, which was 1 equivalent. When Na ⁺ permeated through the membrane, the amount of Ca ²⁺ permeated through the membrane was 2.1 equivalents.

In addition, the electrodialyzed pyrrole-impregnated membrane was taken out and equilibrated with 1N hydrochloric acid, and then
After drying under reduced pressure, the electrical conductivity was measured and found to be 28 Ω-cm ² . On the other hand, the above cation exchange membrane in which pyrrole was not impregnated and polymerized had an electrical resistance of 20 MΩ-cm ² or more when measured under the same conditions.

The cation exchange membrane used above was produced by copolymerizing styrene and divinylbenzene, and the divinylbenzene content 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 ethylene, divinylbenzene and 4-vinylpyridine, and then benzoyl peroxide, which was a polymerization initiator, was added to form a viscous pasty mixture. 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 added to an alkylation bath consisting of a mixed solution of hexane and methyl iodide for 25 minutes.
C. for 24 hours to obtain an anion exchange membrane having a quaternary ammonium base as an anion exchange group.

This anion exchange membrane is made of ammonium persulfate.
After converting the ion exchange membrane into a persulfate ion type by immersing it in a 5% aqueous solution, it was immersed in an aqueous solution in which 5% aniline was dispersed and stirred at room temperature for 8 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 mirabilite and 0.25N common salt was electrodialyzed in the same manner as in Example 1 to obtain SO ₄ ^--.
The membrane permeability of Cl ^- was compared. As a result, 0.3 equivalents of SO ₄ -- per 1 equivalent of Cl ⁻ permeated through the membrane that was not impregnated with aniline and polymerized, but only 0.01 equivalent of ^SO ₄ ^-- permeated in the membrane in which aniline was polymerized within the membrane. It did not pass through the membrane.

The anion exchange membrane impregnated with aniline and polymerized after electrodialysis was dried under reduced pressure, and then the electrical conductivity was measured, and the electrical resistance was 12Ω-
It was warm in ^cm2 .

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 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 cation exchange capacity of the amphoteric ion exchange membrane thus obtained was 0.81 meq/g dry membrane, and the anion exchange capacity was 1.12 meq/g dry membrane. The following two treatments were performed using this amphoteric ion exchange membrane.

(a) When the membrane was immersed in an aqueous solution of ruthenium trichloride to convert it to the ruthenium ion type, then washed and dried with water, and then immersed in a 2% pyrrole aqueous solution, pyrrole was impregnated into the amphoteric ion exchange membrane. Polymerized. After washing with water and methanol, drying under reduced pressure, and measuring the electrical conductivity, the electrical resistance was 25Ω.
^-cm2 .

(b) After being immersed in a 5% aqueous solution of sodium persulfate to form a persulfate ion form, it is immersed in a 1% aqueous solution of aniline with stirring to polymerize, and this is washed with water.
After washing with methanol and drying under reduced pressure,
It showed an electrical conductivity of 19Ω-cm ² .

Furthermore, when both membranes were electrodialyzed with a 1:1 mixed solution of 0.25N hydrochloric acid and 0.25N table salt, the membrane impregnated with pyrrole had a current efficiency of 95%.
Thus, 21 equivalents of hydrogen ions per 1 equivalent of Na ⁺ permeated through the membrane. In addition, the membrane impregnated with polyaniline has a current efficiency of 97%, and hydrogen ions per equivalent of Na ⁺
30 equivalents passed through.

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, the styrene region, the butadiene region,
It was divided into N,N'-dimethylvinylbenzylamine regions. 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 exchange group regions, neutral regions, and anion exchange group regions are distributed in a mosaic pattern is immersed in an aqueous solution of iron trichloride to exchange iron ions into cation exchange groups. I let it happen. Next, when this was immersed in a 2% acetonitrile solution of pyrrole, pyrrole was impregnated mainly in the region where sulfonic acid groups were present and oxidatively polymerized.

When the permeability of table salt and sucrose was measured using the membrane-like material obtained above, it was found that the membrane impregnated with pyrrole and not undergoing oxidative polymerization had a permeability coefficient of 1/1 for sucrose compared to that of table salt.
81, but the permeability coefficient of the membrane impregnated with pyrrole and subjected to oxidative polymerization was reduced to 1/210. Also,
When we measured the conductivity of another membrane made in the same way by washing it with water and methanol and drying it under reduced pressure, we found that the membrane had conductivity in the thickness direction, but had no conductivity at all in the two-dimensional direction of the membrane. In other words, it was an anisotropically conductive film.

Example 5 A mixture of styrene and divinylbenzene is mixed with fine polyethylene powder to make a viscous paste 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 5% aqueous solution of ruthenium trichloride to form a ruthenium ion type, and then immersed in a 10% pyrrole ethyl alcohol solution for 16 hours, resulting in pyrrole impregnation and oxidation only in the sulfonic acid groups. Polymerized. When the conductivity was measured after washing with water, methanol, and drying under reduced pressure, it was found that only one side of the membrane was conductive in the two-dimensional direction, 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 react with chloromethyl groups. introduced on one side of the membrane. Next, this membrane was immersed in a water-acetone solution of trimethylamine to carry out an amination reaction, thereby producing a membrane having a sulfonic acid group on one side and a quaternary ammonium base on the other side. This membrane was immersed in a 5% aqueous solution of sodium persulfate to change the anion exchange group to a persulfate ion type.
% aniline in ethanol solution. After 10 hours, aniline had been polymerized at the anion exchange group. This part was found to be electrically conductive.

Next, this membrane was immersed in a 5% aqueous solution of ferric chloride to exchange iron ions into the cation exchange group, and after washing with water, it was immersed in a 2% ethanol solution of pyrrole, and the cation exchange group was removed. Pyrrole was polymerized in the area where is present, and when the conductivity was measured after washing with water and drying under reduced pressure, 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) After equilibrating a sulfonic acid type cation exchange resin with an aqueous solution of ferric chloride, it was immersed in a 10% aqueous solution of pyrrole and left to stand. When the slightly brown cation exchange resin turned black and polymerized.

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

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

All of the resins a), b), and c) above were found to have electrical conductivity as a result of measurement after being dried under reduced pressure.

Example 8 Polychloromethylstyrene was extruded through a nozzle to obtain a tubular polymer. This was contacted with a solution of aluminum chloride in carbon disulfide to form a crosslinking reaction with Friedelfurf's acid.
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 equilibrated in an aqueous ammonium persulfate solution and immersed in an aqueous solution of pyrrole.

When the electrical conductivity of the above-described tubular material was measured, no conductivity was observed in the tubular material in which pyrrole was not polymerized, but electrical conductivity was observed in the tubular material in which pyrrole was polymerized.

Example 9 Fine powder of a cation exchange resin obtained by sulfonating a copolymer of styrene and divinylbenzene was mixed with polyethylene and extruded from a nozzle in the same manner as in Example 8 to form a tubular cation exchanger. Synthesized. After boiling this in pure water, immersing it in an aqueous solution of iron trichloride to form an iron mold, immersing it in a 2% aqueous solution of thiophene, heating it to 50℃, and leaving it for 24 hours. did. 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 polymerizing a monomer capable of oxidative polymerization in an ion exchanger containing an oxidizing agent.