JPH07258436A - Double layer ion exchange resin membrane and its production - Google Patents

Abstract

PURPOSE:To obtain a double layer ion exchange membrane, excellent in mechanical strength, diffusion dialytic properties and performance stability without losing the hydrophilicity even for a system containing an oxidizing substance by laminating a specific ion exchanger layer to a hydrophilic porous material layer. CONSTITUTION:This double layer ion exchange resin membrane is obtained by laminating (A) an ion exchanger layer containing a polymer having an aromatic ring in the main chain of an aromatic polymer, etc., prepared by introducing a sulfonate group, a primary to a tertiary amino or a quaternary ammonium salt group into a polymer containing a recurring unit expressed by the formula I-X-Ar-Y {X and Y each is O or S; Ar is a group expressed by formula II (R1 is a 1-8C hydrocarbon group; a is 0-3), formula III [W is X or a group expressed by formula IV (R6 and R7 each is H or a 1-6C hydrocarbon group); R2 and R3 each is R1; b+c is 0-7] as a base polymer to (B) a hydrophilic porous material layer obtained by applying a fluorine-containing sulfonic acid polymer having 0.6-2.5mequiv./g resin ion exchange capacity to a porous material membrane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer ion exchange membrane and a method for producing the same, and more particularly to a multi-layer ion exchange membrane having excellent diffusion dialysis performance and a diffusion dialysis performance having such excellent performance. The present invention relates to a method for producing a multi-layer ion exchange membrane, which can produce a multi-layer ion exchange membrane without elution of a low-molecular substance as an impurity at the time of use with a simple device and without causing damage to a porous membrane.

[0002]

BACKGROUND OF THE INVENTION Many documents and patents have been reported on ion exchange membranes, but the most practical and useful ones are sulfonated cations of styrene-divinylbenzene copolymers. Examples include exchange membranes and amination anion exchange membranes of chloromethylated polymers. In addition to having excellent chemical resistance and heat resistance, they can control ion exchange characteristics and selective permeability by changing the content of divinylbenzene, which is a cross-linking agent. Various varieties have been synthesized and developed.

However, in contrast to conventional ultra-low resistance ion exchange membranes useful for new applications such as seawater concentration for producing inexpensive salt equivalent to industrial salt, and separators for redox flow batteries and methanol batteries, conventional styrene-divinylbenzene-based compounds are used. There is a drawback that the above polymer cannot be used.

That is, in order to reduce the resistance, it is necessary to reduce the film thickness, but since the styrene-divinylbenzene resin has mechanical strength, particularly brittleness, it is necessary to form an ion exchange membrane of 100 μm or less. I can't. further,
The styrene-divinylbenzene-based resin has not only good mechanical properties but also poor processability, so that it cannot be formed into a membrane such as a hollow fiber type or a porous ion exchange membrane.

Therefore, we have proposed a styrene-divinylbenzene-based anion exchange membrane as a membrane that exhibits high permeation performance by compensating for those drawbacks, as disclosed in JP-A-2-265929. An ion exchange membrane is presented, which is a multilayer of an ion exchange membrane using a ring-containing polymer and a hydrophilized porous membrane of polyolefin or fluoropolyolefin. This ion exchange membrane is
From the viewpoint of corrosion resistance and heat resistance, it has characteristics superior to conventional styrene-divinylbenzene-based membranes, and also has a high mechanical strength of the ion exchanger and that it is laminated on a porous membrane having a relatively small pore size. By this, the ion exchanger layer can be made thinner and a membrane having higher acid permeability than the conventional membrane can be obtained.

However, when the ion exchange membrane is used in a system containing a substance having a high oxidizing power such as hydrofluoric acid, nitric acid, hydrogen peroxide, and an oxidizing metal, the hydrophilic substance in the ion exchange membrane deteriorates due to oxidation. Are eluted from the ion exchange membrane, which significantly reduces the hydrophilicity of the ion exchange membrane. As a result, air bubbles adhere to the surface of the ion exchange membrane and its performance deteriorates, or if the ion exchange membrane is once dried for some reason such as trouble, the liquid will not penetrate into the ion exchange membrane thereafter. There are drawbacks.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art. The object of the present invention is to say that the hydrophilicity of the support porous membrane is not lost even in a system containing a substance having a high resistance, a low resistance and a high permeability, a stable performance, and a high oxidizing power. It is to provide an ion exchange membrane having excellent performance. The object of the present invention can be clarified by the following description or documents submitted by the applicant after the application of the present application, such as a written opinion.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention is directed to an ion exchanger layer containing a polymer having an aromatic ring in its main chain as a base polymer, and a porous membrane having an ion exchange capacity of 0. A multi-layered ion-exchange membrane characterized by being laminated with a hydrophilized porous body layer obtained by adhering a fluorine-containing sulfonic acid polymer of 6 to 2.5 meq / g resin. Ion exchange capacity of body membrane is 0.6-2.5
Fluorine-containing sulfonic acid polymer of milliequivalent / g resin is attached to form a hydrophilized porous layer, and the hydrophilized porous layer is laminated with an ion-exchange layer made of a polymer having an aromatic ring in the main chain. And a method for producing a multilayer ion exchange membrane.

In principle, the present invention comprises depositing a specific fluorinated sulfonic acid polymer on a specific ion-exchanger layer and a porous membrane having a polymer having an aromatic ring in the main chain as a base polymer. Which is a combination of a specific hydrophilized porous material layer, the ion selectivity, for example, cation selectivity or anion selectivity, depends on the ion exchanger layer, and the hydrophilized porous material layer exclusively uses the ion exchanger layer. Based on the idea of supporting and reinforcing.

In a preferred embodiment of the present invention, the ion-exchange layer having a high electric resistance is prepared to have a minimum thickness necessary for exhibiting selective ion permeability, and the ion-exchange layer has a low electric resistance. In addition, it is based on the principle that it is supported by a porous layer having high mechanical strength. In this case, since the porous body layer is hydrophobic in itself, if this multi-layered ion exchange membrane is used in an aqueous solution system, it is necessary to hydrophilize the porous body layer. However, when a multilayer ion-exchange membrane having a porous body layer that has been subjected to a hydrophilic treatment with an ordinary hydrophilic polymer substance is used in a system containing a substance with high oxidizing power, the hydrophilic polymer causes deterioration due to oxidation. Elute from the multilayer ion exchange membrane. Therefore, in the present invention, the hydrophilic treatment of the porous layer is performed using a specific hydrophilic polymer, that is, a fluorinated sulfonic acid polymer having a specific ion exchange capacity.

The ion exchange layer in the present invention is not particularly limited as long as a polymer having an aromatic ring and having an ion exchange group is used as a base polymer. A polymer having a linking group and having an ion exchange group introduced therein is preferable.

Examples of the ion exchange layer include a copolymer of styrene, chloromethylstyrene and divinylbenzene, a vinylpyridine polymer, a vinylaniline polymer, a vinylimidazole polymer, a polyphenylene oxide, a polyetherimide. , Engineering materials such as polyetherketone, polyetheretherketone, polyethersulfone, and polysulfone are used as base polymers, and sulfonic acid groups in the aromatic ring are
A polymer in which at least one ion exchange group selected from the group consisting of a tertiary amino group and a quaternary ammonium salt group is introduced can be given.

In addition to the above, the preferable ion exchanger layer has an aromatic ring in the main chain from the viewpoint of excellent mechanical properties, heat resistance, chemical resistance and thin film formability, and At least one repeating unit has the general formula (Formula 2)

[0014]

[Chemical 2]

In the aromatic polymer represented by the formula (1), at least one ion exchange group selected from the group consisting of a sulfonic acid group, a primary to tertiary amino group and a quaternary ammonium base is introduced into the aromatic ring. The polymer obtained can be mentioned.

When the ion-exchange layer is an aromatic block copolymer composed of a segment having an ion-exchange group introduced therein and a segment having no ion-exchange group substantially introduced therein, the multi-layer structure according to the present invention. It is preferable because the ion exchange membrane has excellent mechanical properties and can be made into a thin film, and thus has high ion permeability.

As the aromatic block copolymer,
Having an aromatic ring in the main chain and having at least one repeating unit represented by the general formula (Formula 3)

[0018]

[Chemical 3]

An aromatic block copolymer represented by

As the aromatic block copolymer, for example, polyphenylene oxide / polyether sulfone block copolymer, polyphenylene sulfide / polyether sulfone block copolymer, polyaryl ether ether sulfone / polyether sulfone block copolymer. , Polyaryl ether arylate / polyacrylate block copolymers, and polyaryl ether sulfone / polythioether sulfone block copolymers.

Among the above ion-exchanger layers, the general formula (Formula 4) is preferable.

[0022]

[Chemical 4]

An aromatic block copolymer represented by the following formula, in which at least one ion exchange selected from the group consisting of a sulfonic acid group, a primary to tertiary amino group and a quaternary ammonium base is present in the aromatic ring. Examples thereof include polymers having a group introduced.

The ion-exchanger layer having such an aromatic block copolymer is excellent in chemical resistance, ion selectivity, moldability and mechanical properties, can be formed into a thin film, and has low resistance. It has the excellent characteristics of being present.

A method of introducing a sulfonic acid group into at least a part of aromatic rings in a polymer having aromatic rings, 1 to 3.
The method of introducing a primary amino group and / or a quaternary ammonium salt group is described in JP-A 1-215348 by the applicant of the present invention.
It is described in Japanese Patent Application Laid-Open No. 2-212157 and Japanese Patent Application Laid-Open No. 5-228344.

More specifically, in order to introduce a primary to tertiary amino group and / or a quaternary ammonium base into at least a part of the aromatic ring in the polymer having an aromatic ring, (a) an aromatic ring such as A method of introducing an aminoalkyl group into a benzene ring or a naphthalene ring and converting it into a quaternary ammonium salt by reacting with an alkyl halide if necessary, (b) substituting a haloalkyl group for hydrogen on an aromatic ring such as a benzene ring or a naphthalene ring And NH ₃ , 1
~ A method of reacting with a secondary amine or a tertiary amine,
(C) When an alkyl group is introduced into an aromatic ring such as a benzene ring or a naphthalene ring, a method of converting the alkyl group into a haloalkyl group and then reacting with an amine can be mentioned.

Among these various methods, the reaction proceeds easily, the ion exchange capacity can be easily adjusted, and the crosslinking can be introduced by utilizing the reactivity of the haloalkyl group. (B) Method and (c)
The method utilizing the haloalkylation-amination reaction of is preferable.

As a method of introducing a haloalkyl group,
(B) a method comprising chloromethyl methyl ether,
A method utilizing electrophilic substitution reactive chlormethylation reaction using 1,4-bis (chloromethoxy) butane, 1-chloromethoxy-4-chlorobutane, formalin-hydrogen chloride, paraformaldehyde-hydrogen chloride, and the like, and c) a method of directly halogenating an alkyl group with chlorine or bromine, a method of brominating in the presence of light using N-bromosuccinimide, and a method of halogenating in the presence of a phase transfer catalyst Etc. can be mentioned.

Thus, a haloalkylated, eg chloromethylated polymer, ie a haloalkylated polymer, is
Preferably, a multilayer ion exchange membrane can be prepared by the following method.

(A) A haloalkylated polymer such as a chloromethylated polymer is dissolved in a solvent, and an amine is added to the resulting solution to introduce an amino group. (B) A haloalkylated polymer such as a chloromethylated polymer is dissolved in a solvent, the resulting solution is cast to form a film, and then NH ₃ or 1-
Contact with a tertiary amine. (C) A haloalkylated polymer such as a chloromethylated polymer is dissolved in a solvent, a part of the haloalkyl group such as a chloromethyl group, for example, 20 to 80% of a tertiary amine is added to obtain an anion exchange resin solution, which is cast. Then, after forming a film, the remaining haloalkyl group, for example, chloromethyl group, is heat-treated, brought into contact with a Lewis acid, or reacted with an amine having at least two or more amino groups to introduce a crosslinked structure.

As a method of introducing a sulfonic acid group into at least a part of the aromatic ring in the polymer having an aromatic ring, (1) any one of the above-mentioned various polymers having an aromatic ring in the main chain, or its Form two or more in a predetermined shape,
Method of sulfonation after curing, (2) after molding any one or two or more of the various polymers having an aromatic ring in the main chain into a predetermined shape, sulfonation, then curing And (3) a method of sulfonating any one or more of the various polymers having an aromatic ring in the main chain, followed by molding and curing. Among these, the above (3) is preferable because it is easy to control the sulfonation reaction and the curing reaction.

The above description extends to the introduction of a sulfonic acid group into a polymer having an aromatic ring in the main chain and the formation of an ion exchanger formed by introducing a sulfonic acid group. In order to introduce a sulfonic acid group into a polymer having an aromatic ring in the main chain or a cured product thereof, a method of contacting a film material of the polymer having an aromatic ring in the main chain with a sulfonating agent is not effective. However, the polymer having an aromatic ring in the main chain and the sulfonating agent can be dissolved in a solvent that can dissolve the polymer having an aromatic ring in the main chain and is stable to the sulfonating agent. It is preferable to react these in liquid form.

Examples of the solvent in this case include halogenated hydrocarbons such as trichloroethane and tetrachloroethane.

As the sulfonating agent, concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, sulfuric anhydride, sulfuric anhydride-triethylphosphate complex and the like can be used without limitation.

In this way, for example, a sulfonic acid group can be introduced by reacting a polymer having an aromatic ring in the main chain with a sulfonating agent in a solvent, and the concentration of the reactant and the reaction temperature can be controlled. By appropriately setting the reaction time, an ion exchanger having a desired ion exchange capacity can be obtained.

The ion exchange capacity of the ion exchange layer comprising a polymer having an aromatic ring in the main chain is usually 0.5 to 3.5 meq / g dry resin, preferably 1.0 to 3.0 meq. / G dry resin, more preferably 1.5 to 2.5 meq / g dry resin. Also, this ion exchange capacity is
The range from the minimum ion exchange capacity of the ion exchanger layers adopted in the examples of this specification to the maximum ion exchange capacity of the ion exchanger layers adopted in other examples is a suitable ion exchange capacity. It can also be a range. In some cases, the maximum ion exchange capacity of the ion exchanger layers used in the examples of the present specification is set as the upper limit value, and 0.5
The range of ion exchange capacity having a lower limit value of meq / g dry resin, 1.0 meq / g dry resin or 1.5 meq / g dry resin is set as a preferable range, or in the examples of this specification. With the minimum ion exchange capacity of the adopted ion exchanger layers as the lower limit value, the above-mentioned 3.5 meq / g dry resin, 3.0 meq / g dry resin or 2.5 meq / g dry resin is used. The range of the upper limit value can be set as a preferable range of the ion exchange capacity. Generally speaking, when the ion exchange capacity is smaller than 0.5 meq / g dry resin, the membrane resistance sharply increases, and when the ion exchange capacity is smaller than the lower limit value of each ion exchange capacity, the membrane resistance may suddenly increase in some cases. , And generally higher than 3.5 meq / g dry resin, the selectivity and mechanical strength sharply decrease,
If it is larger than the upper limit value of each ion exchange capacity described above, the selectivity and mechanical strength may suddenly decrease.

The thickness of this ion exchanger layer is usually 1 to 3.
It is 0 μm, preferably 5 to 25 μm, and more preferably 7 to 20 μm. Further, the film thickness of this ion exchanger is from the minimum film thickness of the ion exchange layers adopted in the examples of this specification to the maximum film thickness of the ion exchange layers adopted in other examples. It is also possible to set the range up to 1 to a suitable film thickness range. In some cases, the maximum film thickness of the ion-exchanger layers employed in the examples of the present specification is set as the upper limit value, and the film thickness range having the lower limit value of 1 μm, 5 μm, or 7 μm is set as the preferable range. Alternatively, the minimum film thickness of the ion-exchanger layers employed in the examples of this specification is set as the lower limit value, and the range having the upper limit value of 30 μm, 25 μm, or 20 μm is set as the preferable film thickness range. You can also Generally speaking, if the film thickness is less than 1 μm, it is difficult to form a pinhole-free dense film and the selectivity is lowered.
In some cases, it is difficult to form a pinhole-free dense film, which reduces the selectivity. Generally speaking, it is 30 μm.
If it is thicker, the film resistance will be increased and the permeability will be lowered. If it is larger than the upper limit value of each film thickness, the film resistance will be increased and the permeability will be decreased, which is not preferable.

The porous membrane for laminating the ion exchange layer may be polyethylene, polypropylene, polybutene,
Poly-4-methylpentene-1, ethylene copolymer of ethylene and C3 or more olefin, especially C3-6 olefin, propylene copolymer of propylene and C4 or more olefin, especially C4-6 olefin , And polyolefin such as ethylene-vinyl acetate copolymer, polyvinylidene fluoride, polyvinyl fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, hexafluoropropylene / tetrafluoro Ethylene copolymer, ethylene / tetrafluoroethylene copolymer, tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, chlorotrifluoroethylene / ethylene copolymer, fluoroolefin monomer / Fluoro polyolefin such as olefin-based monomer copolymer can be exemplified.

Among the above-mentioned polyolefins, olefin homopolymers such as polyethylene, polypropylene, polybutene and poly-4-methylpentene-1 are preferable, and olefin homopolymers obtained from olefins having 2 to 4 carbon atoms are more preferable, and polypropylene is more preferable. Is particularly preferable.

The molecular weight of the preferred polyolefin is
50,000 to 200,000 for polyethylene
0, 100,000 to 300,000 for polypropylene
0, poly-4-methylpentene-1 has a melt index value of 20 to 200 g / 10 minutes (ASTM-D1238, 260 ° C., 5 kg), which is an index of molecular weight.

Among the above-mentioned fluoropolyolefins, polyvinylidene fluoride, polyvinyl fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, hexafluoropropylene / tetrafluoroethylene copolymer, Ethylene / tetrafluoroethylene copolymers, tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether copolymers, chlorotrifluoroethylene / ethylene copolymers are preferable, and polytetrafluoroethylene and the like are particularly preferable.

The molecular weight of a suitable fluoropolyolefin is 50,000 to 1 for polyvinylidene fluoride.
20,000, 2,0 for polytetrafluoroethylene
0,000 to 80,000,000, 100,000 to 5,000,000 for polychlorotrifluoroethylene
0, hexafluoropropylene / tetrafluoroethylene copolymer 100,000 to 500,000, ethylene / tetrafluoroethylene copolymer 500,0
It is 00 to 1,000,000.

The pore size of the porous membrane in the present invention is usually 0.01 to 5 μm, preferably 0.02 to 3 μm, more preferably 0.04 to 2 μm. Further, the pore size of this porous body membrane is preferably in the range from the minimum pore diameter of the porous body membranes adopted in the examples of this specification to the maximum pore diameter of the porous body membranes adopted in other examples. It is also possible to set a range of film thickness. In some cases, the maximum pore size of the porous membranes used in the examples of the present specification is set as the upper limit value, and the range of the pore size is 0.01 μm, 0.02 μm, or 0.04 μm as the lower limit value. The preferred range, or
It is also possible to set the minimum pore diameter of the porous membranes used in the examples of this specification as the lower limit value and the range of 5 μm, 3 μm, or 2 μm as the upper limit value as the preferable pore diameter range.

The porosity (also referred to as porosity) of the porous membrane in the present invention is usually 30 to 90%, preferably 4
0 to 85%. In addition, the porosity of this porous body membrane is from the minimum porosity of the porous body membranes adopted in the examples of this specification to the maximum porosity of the porous body membranes adopted in other examples. The range up to the porosity can be set as a suitable range of the porosity. In some cases, the maximum porosity of the porous membranes used in the examples of this specification is set as the upper limit, and
% Or 40% as the lower limit of the porosity range is set as a preferable range, or the minimum porosity of the porous membranes adopted in the examples of this specification is set as the lower limit, and the above 90%
Alternatively, a range having an upper limit value of 85% can be set as a preferable range of porosity.

The thickness of the porous film in this invention is usually 1
The thickness is 0 to 200 μm, preferably 25 to 160 μm, and more preferably 40 to 140 μm. Further, the thickness of this porous body film, from the minimum film thickness of the porous body film adopted in the examples of this specification to the maximum film thickness of the porous body film adopted in other examples The range can be a suitable film thickness range. In some cases, the maximum film thickness of the porous film used in the examples of the present specification is set as the upper limit value, and 10
The range of the film thickness having a lower limit value of μm, 25 μm, or 40 μm is set as a preferable range, or the minimum film thickness of the porous film used in the examples of the present specification is set as the lower limit value,
The range having the upper limit of 200 μm, 160 μm, or 140 μm can be set as a preferable range of the film thickness.

The pore diameter of the porous film is smaller than 0.01 μm, the porosity is lower than 30%, or the film thickness is 200 μm.
If the thickness is thicker, the resistance of the membrane increases and high permeability cannot be obtained. If the pore diameter is larger than 5 μm, the ion exchange membrane laminated thereon cannot be made thin and high permeability cannot be obtained, and the porosity is high. If it is higher than 90% or the film thickness is thinner than 10 μm, the strength of the film is lowered, which is not preferable.

There are various methods for producing the porous body membrane, and the stretch opening method is used as a preferable method. The stretch-opening method is a method in which a polymer is molded into a hollow fiber or a film and then stretched to open the pores to form a porous structure.
In the stretch-opening method, a porous membrane can be obtained by a physical means, and the pore diameter is relatively small, so that the surface smoothness and porosity are high, and a membrane having high mechanical strength can be obtained. Therefore, it is suitable as a method for producing the porous membrane used in the present invention.

As a method of laminating the ion exchange layer on such a porous membrane, a method of melting and laminating the ion exchange layer and the porous body, a method of coating the ion exchange polymer solution on the porous body, an ion exchange polymer A method of laminating the ion exchange layer and the porous body with the solution as an adhesive, followed by drying, a method of polymerizing or grafting after applying a monomer, and the like are conceivable, but a method of coating the ion exchange polymer solution on the porous body membrane. The method of laminating and drying the ion exchange layer and the porous membrane using the ion exchange polymer solution as an adhesive is preferably used in the present invention because a dense thin film can be formed.

As a method of hydrophilizing the porous membrane which is the support of the multi-layered ion exchange membrane, it may be considered to physically adsorb a hydrophilic polymer substance to the porous membrane. Also,
There is also a method of physically adsorbing a hydrophilic low molecular weight substance on the porous body membrane, but this is not preferable because the hydrophilic low molecular weight substance is easily eluted during use. There is also a method of immobilizing a hydrophilic substance with radiation such as an electron beam or an ultraviolet ray, and a method of hydrophilizing the porous membrane itself by surface modification with fuming sulfuric acid, chlorosulfonic acid, chromic acid, plasma gas, ozone gas and the like. However, the size of the device becomes large and the porous membrane is damaged, which is not preferable.

Examples of the hydrophilic macromolecular substance preferable in the present invention include fluorinated sulfonic acid polymers. Even if a hydrophilic polymer substance other than the fluorine-containing sulfonic acid polymer is used, the object of the present invention cannot be achieved.

[0051]

[Chemical 1]

The perfluorosulfonic acid polymer represented by is excellent in oxidation resistance and is suitable for use in the present invention.

Among the fluorine-containing sulfonic acid polymers represented by the above (Chemical formula 1), the T _Q value which is an index of the average molecular weight (1 mm in length and 1 in diameter by a flow tester device)
When a polymer is extruded from a nozzle of mm with a load of 30 kg, the temperature at which the polymer is extruded at a rate of 0.1 ml / sec) is 120 to 350 ° C. (JIS K-72).
10, L / D = 1, 30 kg), especially 150 to 2
It is preferably 50 ° C. In other words, in the fluorine-containing sulfonic acid polymer represented by the above (Chemical formula 1), p in the above (Chemical formula 1) is 60 to 95 mol%, particularly 75
To 90 mol%, q is 5 to 40 mol%, particularly 10 to
A fluorine-containing sulfonic acid polymer having a content of 25 mol%, r of 0 to 1, s of 1 to 5, and particularly 1 to 3 is preferable. X is a hydrogen atom or an alkali metal atom (for example, N
a, K, etc.) or an alkaline earth metal atom.

The polymer solution coating method is a preferable method for adsorbing the above hydrophilic polymer substance to the porous membrane because a dense thin film can be formed on the surface of the porous body. In this invention, the ion-exchange membrane and the porous membrane are laminated using a solution, or the ion-exchange solution is cast on the porous membrane to form a membrane. Since the hydrophilic polymer may be partially eluted depending on the solvent at this time, it is preferable to perform the hydrophilic treatment after forming the laminated film in order to stably exhibit the performance.

[0055]

The present invention will now be described with reference to examples, but the present invention is not limited to these examples.

(Example 1) In the same manner as the synthesis method described in JP-A-61-168629, 0.36 mol of 4,4'-diphenol and 0.39 of dichlorodiphenyl sulfone were added.
6 mol was reacted to synthesize 0.36 mol of a precursor m = 10 composed of an aromatic polysulfone unit,
Next, 0.36 mol of the precursor, 0.324 mol of dichlorodiphenyl sulfone and 0.378 mol of sodium sulfide.
Aromatic polysulfone-polythioether sulfone copolymer 2 represented by the following formula by reacting with
20 g was obtained.

[0057]

[Chemical 5]

(However, m / n is 1/1. The intrinsic viscosity of the aromatic polysulfone-polythioether sulfone copolymer is 0.50.) 75 g of the obtained copolymer is 1,1, It was dissolved in 1,020 ml of 2,2-tetrachloroethane, 400 g of chloromethyl methyl ether and 4.5 g of anhydrous tin chloride were added, and the mixture was reacted at 110 ° C. for 4 hours. After the reaction, it was precipitated with 5,000 ml of methyl alcohol and washed to obtain 85 g of a chloromethylated copolymer.

50 g of the obtained chloromethylated copolymer was dissolved in 300 ml of N, N-dimethylformamide to prepare 1
A 5 wt% solution was prepared. While cooling and stirring, 115 ml of a 1N trimethylamine N, N-dimethylformamide solution was slowly added dropwise at -10 ° C, and a predetermined amount of 2 was added after the addition.
-Methoxyethanol was added. In this way, 520 ml of N, N-dimethylformamide solution A of quaternary aminated polymer having an ion exchange capacity of 2.0 meq / g.
Got

30 ml of aminated polymer solution A was cast on a polyester film to form an ion exchange layer B having a thickness of 7 μm.

Further, 30 ml of aminated polymer solution A was diluted with 42 ml of N, N-dimethylformamide, and 72 ml of aminated polymer adhesive solution C having a polymer concentration of 5% by weight.
Got

The aminated polymer adhesive liquid C was coated on the ion-exchanger layer B so that the liquid film thickness was 20 μm, and was prepared by a stretch opening method. Is 50 μm and the pore size is 0.1.
A polypropylene porous film D having a thickness of μm and a porosity of 50% was attached. Then, a multilayer film E was obtained by drying at 50 ° C. for 2 hours. The molecular weight of polypropylene forming the porous film D was 200,000.

On the other hand, using azobisisobutyronitrile as an initiator, 0.2 mol of tetrafluoroethylene and CF ₂ =
CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ SO ₂ F
Copolymerization with 0.045 mol was carried out under polymerization conditions of a polymerization temperature of 70 ° C. and a polymerization time of 5 hours to obtain a fluorinated polyolefin copolymer having an ion exchange capacity of 1.1 meq / g. This is hydrolyzed in a 20% KOH aqueous solution at 90 ° C. for 16 hours, immersed in 1N hydrochloric acid at room temperature for 16 hours to be converted into an acid form, and dissolved in ethanol to make a hydrophilic solution having a concentration of 1%. F1,500 ml was obtained.

The hydrophilic film F was coated on the porous film side of the multilayer film E. The film thickness of the coated liquid was 100 μm. Then, it was dried at a temperature of 50 ° C. for 30 minutes for hydrophilic treatment to obtain a multilayer ion exchange membrane.

The hydrophilized multi-layered ion exchange membrane was sandwiched between dialysis cells, and an aqueous solution containing 3M sulfuric acid and 0.5M iron sulfate was brought into contact with one surface and ion exchanged water was brought into contact with the other surface. It was The initial acid permeation coefficient and selectivity of this multi-layered ion exchange membrane were determined from the amounts of sulfuric acid and iron ions transferred to the ion exchanged water side at this time. The results are shown in the column of initial acid diffusion dialysis performance in Table 1.

Further, this multi-layered ion exchange membrane was mixed with 9% of 3M hydrofluoric acid, 3M nitric acid and their mixed aqueous solution, respectively.
It was immersed at 0 ° C. for 1 month. After the immersion, the multilayer ion exchange membrane was taken out, dried, and then floated on the water surface. It was confirmed that the liquid did not enter the porous membrane and the hydrophilicity was not lost even when the dipping treatment was performed with any of the acids. Further, after dipped in a mixed water solution of hydrofluoric acid and nitric acid at 90 ° C. for 1 month, the diffusion dialysis performance of the dried membrane was measured by the same method as above. The measured values are shown in the column of acid diffusion dialysis performance after immersion drying in Table 1.

Example 2 In Example 1, 1N trimethylamine in N, N-dimethylformamide solution 11 was used.
By changing 5 ml to 69 ml of a 1N trimethylamine N, N-dimethylformamide solution, 475 ml of a quaternary aminated polymer N, N-dimethylformamide solution A having an ion exchange capacity of 1.2 meq / g was obtained.
Instead of the polypropylene porous body membrane D having a pore size of 0.1 μm, a porosity of 50% and a film thickness of 50 μm, the pore size of 1 μm prepared by the stretch opening method. A multilayer film E was obtained in the same manner as in Example 1, except that the polytetrafluoroethylene porous film D having a porosity of 80% was used as the porous film.

The obtained multilayer film E was treated with 5N N, N, N ',
It was immersed in an ethanol solution of N′-tetramethyl-1,3-diaminopropane at 50 ° C. for 16 hours to crosslink the chloromethyl groups remaining in the ion-exchange layer to obtain a crosslinkable multilayer membrane Ea. This multilayer film Ea is used in the first embodiment.
The same hydrophilic treatment as in Example 1 was performed with the same hydrophilic treatment as in Example 1.

The multi-layered ion exchange membrane after the hydrophilization treatment was sandwiched between dialysis cells, and an aqueous solution containing 3M sulfuric acid and 0.5M iron sulfate was brought into contact with one surface and ion exchanged water was brought into contact with the other surface. It was The acid permeation coefficient and selectivity of this multi-layered ion exchange membrane were determined from the amounts of sulfuric acid and iron ions moving to the ion exchanged water side at this time.

Further, the multi-layered ion exchange membrane was mixed with 3M hydrofluoric acid, 3M nitric acid, and a mixed aqueous solution thereof, respectively.
It was immersed at 0 ° C. for 1 month. After the immersion, the multilayer ion exchange membrane was taken out, dried, and then floated on the water surface. It was confirmed that the liquid did not enter the porous membrane and the hydrophilicity was not lost even when the dipping treatment was performed with any of the acids. Further, the diffusion dialysis performance of the membrane immersed in a mixed water solution of hydrofluoric acid and nitric acid was measured by the following method. Table 1 shows the measured values of the diffusion dialysis performance.

Comparative Example 1 A laminated multi-layer ion exchange membrane was prepared in the same manner as in Example 1 except that 1% polyvinyl alcohol water / methanol solution was used as the hydrophilizing solution F. .

With respect to the prepared laminated multilayer ion exchange membrane, the acid diffusion dialysis performance measurement and the immersion test of the membrane were carried out in the same manner as in Example 1. In any of the immersion tests, the liquid did not penetrate into the porous membrane and the hydrophilicity was lost. Table 1 shows the measured values of the diffusion dialysis performance.

Comparative Example 2 A laminated ion-exchange membrane was prepared in the same manner as in Example 2 except that 1% polyethyleneimine in water / methanol was used as the hydrophilic solution F. With respect to the prepared laminated ion exchange membrane, the acid diffusion dialysis performance measurement and the immersion test of the membrane were carried out in the same manner as in Example 1. In any of the immersion tests, the liquid did not penetrate into the porous membrane and the hydrophilicity was lost. Table 1 shows the measured values of the diffusion dialysis performance.

Example 3 A laminated ion-exchange membrane was prepared in the same manner as in Example 2 except that the porous membrane was laminated after the hydrophilic treatment. With respect to the prepared laminated ion exchange membrane, the acid diffusion dialysis performance measurement and the immersion test of the membrane were carried out in the same manner as in Example 1. In the immersion test, in the case of the mixed solution of hydrofluoric acid and nitric acid, there was a part where the solution did not enter the porous membrane. Table 1 shows the measured values of the diffusion dialysis performance.

[0075]

[Table 1]

From the results of Examples 1, 2 and 3 and Comparative Examples 1 and 2, the polymer having an aromatic ring in the main chain was used as the base polymer as the ion exchanger layer made of the polymer having the aromatic ring in the main chain. And especially aromatic polysulfone
Using a polythioether sulfone copolymer as a base polymer and using an ion exchange layer obtained by introducing ion exchange groups such as amino groups into the base polymer, a polyolefin membrane, particularly polypropylene or fluoropolyolefin, especially polypolyolefin is used as a porous membrane. It is tetrafluoroethylene and has a film thickness of 10 to 200 μm, especially 40 to 1
40 μm, pore diameter 0.01 to 5 μm, especially 0.04 to 2
Using a porous membrane having a micrometer and a porosity of 30 to 90%, especially 40 to 85%, the chemical formula 1 is shown, and the ion exchange capacity is 0.6 to 2.5 meq / g dry. Fluorine-containing sulfonic acid polymer which is a resin, especially tetrafluoroethylene and CF having an ion exchange capacity of 0.9 to 1.2 meq / g dry resin centered on 1.1 meq / g dry resin ₂ = CF ₂ OCF (CF ₃ ) _j O (CF ₂
) _K SO ₂ F (where j is 0 to 1 and k is 1 to
It is 5. When a fluorine-containing sulfonic acid polymer obtained by copolymerizing with) is used for the hydrophilization treatment, the obtained multilayer ion-exchanger has a high acid permeability coefficient and selectivity, and is immersed in a strong acid for a long time. It is understood that its hydrophilicity is not lost, and therefore it is also excellent in oxidation resistance and there is no elution by strong acid.

Comparing the above-mentioned Examples and Comparative Examples, the porous membrane which has not been subjected to the hydrophilization treatment is laminated on the ion-exchange layer whose base polymer is a polymer having an aromatic ring in the main chain, and then hydrophilized. The multilayer ion-exchange membranes obtained by the treatment (Examples 1 and 2) are based on the hydrophilized porous membrane obtained by hydrophilizing the porous membrane and the polymer having an aromatic ring in the main chain. It is more excellent in hydrophilicity retention than the multilayer ion-exchange membrane (Example 3) obtained by laminating the ion-exchange layer.

[0078]

EFFECTS OF THE INVENTION According to the present invention, the hydrophilized multi-layered ion-exchange membrane is an ion having excellent acid permeation performance and oxidation resistance on a porous membrane having a high mechanical strength and a relatively small pore size. Since it is obtained by laminating exchange thin films and hydrophilizing the originally hydrophobic porous body layer with a hydrophilic polymer having excellent oxidation resistance, low resistance, high permeability and stable performance are exhibited, Moreover, it is possible to provide an ion exchange membrane having excellent performance without losing the hydrophilicity of the porous support membrane even for a system containing a substance having a high oxidizing power, and a simple production method thereof.

Claims (7)

[Claims] 1. An ion-exchange layer comprising a polymer having an aromatic ring in the main chain as a base polymer and a fluorine-containing sulfonic acid having an ion exchange capacity of 0.6 to 2.5 meq / g resin in a porous membrane. A multi-layered ion exchange membrane, which is in a laminated state with a hydrophilized porous body layer formed by adhering a polymer. 2. The porous membrane has a thickness of 10 to 200 μm,
The multilayer ion-exchange membrane according to claim 1, comprising a polyolefin and / or a fluorinated polyolefin having a pore size of 0.01 to 5 µm and a porosity of 30 to 90%. 3. The ion exchanger layer comprises: Wherein at least one ion-exchange group selected from the group consisting of a sulfonic acid group, a primary to tertiary amino group, and a quaternary ammonium base is introduced into an aromatic polymer containing a repeating unit represented by The multilayer ion-exchange membrane described in 1 or 2. 4. The ion exchanger layer comprises: Wherein at least one ion exchange group selected from the group consisting of a sulfonic acid group, a primary to tertiary amino group and a quaternary ammonium base is introduced into an aromatic block copolymer containing a repeating unit represented by The multi-layer ion exchange membrane according to claim 1. 5. The ion exchanger layer comprises: In the polysulfone-polysulfone thioether copolymer containing the repeating unit represented by
The multi-layer ion exchange membrane according to any one of claims 1 to 5, wherein at least one ion exchange group selected from the group consisting of a primary amino group and a quaternary ammonium base is introduced. 6. The porous membrane has an ion exchange capacity of 0.6 to
A fluorinated sulfonic acid polymer of 2.5 meq / g resin is adhered to form a hydrophilized porous layer, and the ion exchange layer is made of the hydrophilized porous layer and a polymer having an aromatic ring in the main chain. A method for producing a multi-layered ion exchange membrane, which comprises laminating and 7. An ion exchange layer having a polymer having an aromatic ring in the main chain as a base polymer and a porous membrane are laminated and integrated, and then the ion exchange capacity is 0.6 to 2.5 meq / m.
A method for producing a multi-layered ion exchange membrane, which comprises subjecting a fluorine-containing sulfonic acid polymer of a g resin to a hydrophilic treatment.