JPH02248434A - Improved cation exchanger - Google Patents

Abstract

PURPOSE:To obtain a cation exchange of excellent processability and high ion permselectivity from a cured mixture of a haloalkylated polysulfone polymer with a sulfonated polysulfone polymer. CONSTITUTION:This cation exchanger is formed from a cured mixture of a polysulfone polymer having at least one haloalkyl in the molecule with a polysulfone polymer having a sulfonic group and has an ion exchange capacity of 0.5-3.5 milliequivalents/g dry resin. A chloromethyl group (-CH2Cl) is desirable as the haloalkyl group. An aromatic polysulfone block copolymer of formula I is desirable as the polysulfone polymer. In formula I, Ar is formula II, formula III or the like; Y is a single bond, -Oor the like; Z is -O-, -S- or the like; R<1> to R<7> are 1-8C hydrocarbon groups which may be the same or different from each other; a-d are each 0-4; e is 0-3; (f+g) is 0-7; and m/n=100/1-1/10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion exchanger that adsorbs or permeates and separates specific components from a mixed fluid.

More specifically, we will introduce cation exchange thin membranes with low resistance useful for electrodialysis such as seawater concentration and battery separators, hollow fiber cation exchange membranes useful for dialysis, and porous cation exchange membranes with high permeability for polymer cations. It relates to cation exchangers with excellent processability, such as membranes.

[Prior Art] Many documents and patents have been reported as cation exchangers, but styrene is the most practical and useful one.
There are sulfonated cation exchangers of divinylbenzene copolymers. In addition to their chemical resistance and heat resistance, by changing the content of divinylbenzene, a crosslinking agent,
Since ion exchange properties and permselectivity can be controlled, a wide variety of products have been synthesized and developed for various uses.

However, the conventional styrene-divinylbenzene system cannot meet the needs of ultra-low resistance cation exchange membranes for new applications, such as seawater concentration to produce salt as inexpensive as industrial salt, and separators for Redok flow batteries and methanol batteries. There is a drawback that it cannot be done. In other words, to lower the resistance.

Although it is necessary to reduce the film thickness, styrene-divinylbenzene resin has mechanical strength, especially brittleness, so
Furthermore, styrene-divinylbenben resin has poor mechanical properties,
Processability is poor, and processed membranes such as hollow fiber type and porous cation exchange membranes cannot be obtained.

On the other hand, polysulfone membranes with excellent mechanical strength and processability are used in ultrafiltration membranes and reverse osmosis membranes, and sulfonated polysulfone membranes are being considered to improve their permeability.

For example, a sulfonated polysulfone whose repeating units are 1'Sl- and I'Is is described in USP 37
09841, and is published in JP-A-50-999.
73, Japanese Patent Publication No. 51-146379. Japanese Patent Publication No. 61-450
No. 5, etc., describes a semipermeable membrane in which such a sulfonated polysulfone is laminated on an anisotropic ultrafiltration membrane.

However, these sulfonated polysulfone membranes
Since it is non-crosslinked, the ion exchange capacity is 2.0 meq/
If the resin is more than g, it becomes water soluble, and even if the ion exchange capacity is low, the water absorption rate is high, so the ion selective permeability is low, and it cannot be used as a substitute for the conventional styrene-divinylbenzene-based cation exchange membrane.

[Problems to be Solved by the Invention] The present invention aims to solve the above-mentioned drawbacks of the prior art, and provides a novel cation exchanger with excellent processability and high ion permselectivity. The purpose is to provide

The purpose of the present invention is to provide a cation exchange membrane that can be used for energy-saving electrodialysis methods, battery separators, and hollow fiber dialysis modules that are compact and easy to maintain, which cannot be achieved with conventional technology. .

[Means for Solving the Problems] The above-mentioned object of the present invention is to provide a mixture of a polysulfone polymer having a small amount (both one or more haloalkyl groups) and a polysulfone polymer containing a sulfonic acid group in one molecule. It is made of a hardened polymer and has an ion exchange capacity of 0.5 to 3.
This is achieved with a cation exchanger that is 5 meq/g dry resin.

The cation exchanger of the present invention basically consists of a cured product of a polysulfone polymer having the above-mentioned specific functional group and a polysulfone polymer containing a sulfonic acid group, which is different from conventional cation exchangers. can provide a cation exchanger with significantly superior properties.

That is, as described in JP-A No. 61-4505, conventional sulfonated polysulfone polymers become water-soluble polymers due to non-crosslinking when their ion exchange capacity exceeds 2.0 milliequivalents/g resin. Therefore, it cannot be used as an ion exchanger.

Polysulfone resins with crosslinking sites are known to contain a 10H group or a -C:1iiCH group at the 7-terminus, but these crosslinking sites have low reactivity and the sulfonic acid group 320~4 above pyrolysis temperature
It requires high-temperature heat treatment at 00°C and is not suitable as a material for producing cross-linked polysulfone-based ion exchange membranes.

The present inventor conducted intensive research on cured products of sulfonated polysulfone polymers, and found that by using polysulfone polymers containing haloalkyl groups in the molecule, the cured products had excellent mechanical properties, moldability, and ion exchange properties. The inventors discovered that a cation exchanger can be produced and completed the present invention.

To explain the present invention in detail below, the polysulfone-based polymer containing a sulfonic acid group constituting the cation exchanger of the present invention includes hydrocarbon groups of general formulas 1 to 8, a - d
is O~4, e is O~3, (f+g) is O~7, (h+i
) represents O~5, R8°, R11 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and m/n JOO10 to 1/100.

), preferably a sulfonated compound of a polymer containing an aromatic polysulfone represented by the general formula -3Q, -, m/n
It can be obtained by sulfonation of an aromatic polysulfone polymer represented by =100/1 to 1/10.

As a method for sulfonating a polysulfone polymer, a method in which a solid polysulfone polymer is brought into contact with a sulfonating agent is also used, but it is preferable to dissolve the polysulfone in a solvent that is stable to the sulfonating agent and dissolves polysulfone. The reaction is preferably carried out using halogenated hydrocarbons such as trichloroethane, tetrachloroethane, etc. as such a solvent.

Further, as the sulfonating agent, concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, sulfuric anhydride, and sulfuric anhydride-triethyl phosphate complex can be used without limitation.

By adding a sulfonating agent to the polysulfone solution and conveniently selecting the reaction temperature and reaction time, a sulfonated polysulfone polymer having a desired ion exchange capacity can be obtained.
．． Below 5 milliequivalents/g resin, the membrane resistance is extremely high;
Furthermore, if the amount exceeds 3.5 milliequivalents/g of resin, a large amount of curing agent is required, resulting in a decrease in the ion exchange capacity of the cured film, and also a decrease in the mechanical strength, especially the toughness, of the resulting film. , preferably an ion exchange capacity of 0.5 to 3.
5 meq/g resin, especially 0.8 to 3.0 meq/g resin
g React to form a resin.

The polysulfone polymer containing a haloalkyl group constituting the cation exchanger of the present invention is a haloalkylated compound of an aromatic polysulfone polymer represented by the general formula, preferably a compound in the general formula, or a different single bond,
-o-, -s-, -so, -, -c- or R8゜hydrocarbon group with prime number 1-8, a-d is 0-4, e is O-
3, (f+g) is O~7, (h+i) is O~5, R1°, R11 is hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, m/n
=10 (indicates 110-1/100) It can be obtained by haloalkylation of an aromatic polysulfone polymer represented by -, m/n = 100/1 to 1/10.

The AD alkyl group is -(CHz) n Cl +
−((: Hz) n B r +−(CHs)n
Examples include F, -(CL)-I, but due to reactivity, -CH*
C1,-CHaBr is preferable, especially -CH
*C4 is preferably adopted.

Methods for introducing such chloromethyl groups include chloromethyl methyl ether, 1,4-bis(chloromethoxy)butane, 1-chloromethotoxy-4-chlorobutane, and nucleophilic chloromethyl such as formalin hydrogen chloride, paraformaldehyde, and hydrogen chloride. It can be obtained by bringing a curing agent into contact with a polysulfone polymer in the presence of a catalyst.

As a method for introducing one -cHs group into the above-mentioned polysulfone-based polymer, it is also possible to use a method in which the chloromethylating agent mentioned above is brought into contact with a particulate polymer or a film-like molded product, but this method is effective in improving the uniformity of the reaction and the ease of molding process. In order to obtain a polymer with good properties, it is preferable to dissolve it in a solvent that is stable against chloromethylating agents and dissolves polysulfone-based polymers, and to react in liquid form. As such solvents, halogenated hydrocarbons such as trichloroethane, tetrachloroethane, etc. are used. Thus, by adding a chloromethylating agent and a catalyst such as tin chloride to a polysulfone polymer solution and appropriately selecting the reaction temperature and reaction time, a chloromethylated polysulfone polymer having a desired chloromethyl group content can be obtained.

The chloromethyl group content of the chloromethylated sulfone polymer varies depending on the mixing ratio of the sulfonated polysulfone polymer and the ion exchange capacity of the sulfonated polysulfone polymer, but is 0.01 milliequivalent/g.
The amount of resin used is at least 0.1 meq/g resin, preferably at least 0.1 meq/g resin, particularly from 0.5 to 3.5 meq/g resin.

Thus, the chloromethylated polysulfone polymer constituting the cation exchanger of the present invention and the above-mentioned sulfonated polysulfone polymer are mixed, and the blending ratio is 1 to 1 of the ion exchange capacity of the sulfonated polysulfone polymer.
In order to obtain a cation exchanger with a large ion exchange capacity (high ion exchange capacity, excellent selectivity, and mechanical properties), it is preferable to blend the chloromethyl group to 200 equivalent %, especially 5 to 50 equivalent %. .

The method of mixing the chloromethylated polysulfone polymer and the sulfonated polysulfone polymer is not particularly limited, and any known mixing method may be applied, but preferably in a common solvent of the two types of polysulfone polymers constituting the present invention. , dissolving and mixing is preferable in order to obtain a cation exchange membrane having uniform physical properties.

Examples of such solvents include single solvents such as dimethylformamide, dimethylsulfoxide, and N-methylpyrrolidone, as well as water/acetone mixtures, methanol/tetrahydrofuran mixtures, tetrachloroethane/alcohol mixtures, and the like.

Thus, the solution of the chloromethylated polysulfone polymer and the sulfonated polysulfone polymer is cast into a desired shape, dried, and molded to obtain a cation exchanger, but the solution must be brought into contact with an acid before or after such molding. is preferred.

The above acids include A I C1B , S bCl s
+ F e Cl s + T e C1m *5n
C14, TiCl4. TeCl4. B1C1a, Z
Lewis acids such as nC1z and liver, HgSO4, hOs,
Protonic acids such as HsPO4 are exemplified, and a solution of a chloromethylated polysulfone polymer and a sulfonated polysulfone polymer is coexisted with at least one of the above acids, and then cast and dried, or a solution of a chloromethylated polysulfone polymer and a sulfonated polysulfone polymer is used. A molded article of polysulfone polymer can be brought into contact with the above acid.

In addition, as another suitable means for obtaining the cation exchanger of the present invention, by using the ion exchange group of the sulfonated polysulfone polymer as -3O,H, it is possible to simply combine the chloromethylated polysulfone polymer and the sulfonated polysulfone polymer. The molded product cast and dried from the combined solution is 180%
By heating at ~300°C, preferably 220-250°C, a cured cation exchanger that does not require a solvent can be obtained.

The cation exchanger of the present invention thus obtained is used by hydrating the ion exchange group with a convenient solution such as a saline solution. In particular, the present invention can be used as a separation membrane such as an electrodialysis membrane, a battery separator, a diffusion dialysis membrane, etc. in a membrane-shaped molded article in which the cation exchanger of the present invention has a diameter of 100 μm or less. As explained, the present invention includes
The present invention is not limited to such examples.

[Example] Example 1 In the same manner as the synthesis method described in JP-A-61-168629, 4,4'-diphenol and dihalodiphenylsulfone were reacted to obtain a precursor consisting of an aromatic polysulfone unit. and then reacting the precursor with dihalodiphenylsulfone and sodium sulfide,
An aromatic polysulfone-polythioethersulfone copolymer A represented by the following formula was obtained.

B3 K) w, @o (x public o).

+@;P-chaosoS). H (1) m/n = 1 / 1 Intrinsic viscosity 0.65 Next, the copolymer A was dissolved in 1,1,2-trichloroethane, and then a complex of sulfuric anhydride/triethyl phosphate in a local molar ratio was prepared. The copolymer A was brought into contact with a trichloroethane solution containing 2 equivalents of the complex per unit of copolymer A, and reacted at 25°C for 100 hours, followed by washing and drying. The ion exchange capacity of the resulting sulfonated copolymer was 2.05 meq/g resin.

On the other hand, after dissolving copolymer A in 1.1,2.2-tetrachloroethane, chloromethyl ether and anhydrous tin chloride were added and reacted at 108°C for 4 hours, followed by coagulation and washing with methyl alcohol. and the chloromethyl group content is 2.
A chloromethylated copolymer A at 2 meq/g resin was obtained.

75 parts by weight of the thus obtained sulfonated copolymer A and 25 parts by weight of the chloromethylated copolymer A were dissolved in -methylpyrrolidone to obtain a solution with a solid content concentration of 20% by weight.Then, the polymer solution was placed on a glass plate. 260℃1
A cation exchange membrane having a thickness of 25 μm was obtained by heat treatment for a period of time.

The cation exchange membrane thus obtained was 0.5N-NaC.
The AC resistance in one solution was 0.6 Ωcm'', and the Na'' transport number was 0.95. The membrane was soaked in N-methylpyrrolidone but did not dissolve.

Comparative Example 1 A cation exchange membrane was obtained in the same manner as in Example 1 except that the sulfonated copolymer was neutralized to Na type.

The membrane thus obtained had an AC resistance of 0.5ΩC11”,
Although the Na'' transport number was 0.94, it dissolved when the membrane was immersed in N-methylpyrrolidone.

[Effects of the Invention] The cation exchanger of the present invention is characterized by being composed of a crosslinked sulfonated polysulfone polymer. For this reason, depending on the type of curing agent, amount of curing agent, and curing conditions,
By controlling the fixed ion concentration, it is possible to obtain a cation exchange membrane with optimal permselectivity depending on the application, and the resistance to organic solvents is improved.

In addition, since the present invention is characterized by using a chloromethylated polysulfone copolymer as a crosslinking agent, the inherent moldability, mechanical strength, heat resistance, and chemical resistance of polysulfone polymers may be impaired. can be crosslinked without any In particular, when a block copolymer having units with different reactivities is used as a polysulfone polymer, the sulfonic acid group or the chloromethyl group at the crosslinking site is introduced into a specific site, resulting in a high ion exchange capacity and a high crosslinking density. It has the characteristic that a strong film with high mechanical strength can be obtained even if the film has a high mechanical strength.

Furthermore, since it can be cast from a solution containing a sulfonated copolymer and a curing agent, a thin ion exchange membrane can be obtained, and it can also be coated and dried on porous substrates or other polymer membranes. This method has the feature that a multilayer ion exchange membrane can be easily obtained.

Claims (5)

[Claims] (1) Consists of a cured mixture of a polysulfone polymer having at least one haloalkyl group in one molecule and a polysulfone polymer containing a sulfonic acid group, and has an ion exchange capacity of 0.5 to 3.5 meq/g
A cation exchanger characterized by being a dry resin. (2) Film thickness: 1 after casting and heat treatment from a solution containing a polysulfone polymer containing a haloalkyl group, a polysulfone polymer containing a sulfonic acid group, and a Lewis acid.
The cation exchanger according to claim 1, which is a cation exchange membrane with a diameter of 00 μm or less. (3) Patent claim (1) characterized in that the Lewis acid is -SO_3H of a polysulfone polymer containing a sulfonic acid group.
) or the cation exchanger of (2). (4) Patent claims (1) to 1, characterized in that the polysulfone-based polymer containing a haloalkyl group is a polysulfone-based polymer that has been converted to chloromethyl (-CH_2Cl).
(3) Any of the cation exchangers. (5) Polysulfone polymers have a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (However, Ar in the formula ▲ has a mathematical formula, chemical formula, table, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, Y is a single bond, -
O- or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, Z is -O-, -S
- or -SO_2-, R^1 to R^9 are the same or different hydrocarbon groups having 1 to 8 carbon atoms, a to d are 0 to 4, e is 0 to 3, (f+g) is 0 to 7, (h+i) is 0 to 5, R_1_0 and R_1_1 are hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, m/n=100/1 to 1/10. )
The cation exchanger according to claims (1) to (5), which is an aromatic polysulfone block copolymer represented by: