JPH02166128A - Bipolar membrane manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a simple method for producing a Bygate membrane that can decompose water, particularly at low voltage.

[Conventional technology]

The Bygate membrane has a structure in which a cation exchange membrane and an ion exchange membrane are bonded together9, and various methods for manufacturing it have been proposed. For example, cation exchange membrane and anion exchange membrane,
A method of laminating and curing adhesive using a mixture of polyethyleneimine and epichlorohydrin (Japanese Patent Publication No. 32-3962).

Method of adhering a cation exchange membrane and an anion exchange membrane with an ion exchange adhesive (Special Publication No. 34-3961), 11!
A method in which an ion exchange membrane and an anion exchange d% membrane are bonded together by applying a paste F-state compound of a finely powdered ion exchange resin anion or cation exchange resin and a thermoplastic substance (Special Publication Publication No. 1973).
-14531J)), A method of manufacturing by applying a glue-like substance consisting of a vinylpyridine polymer and an oxidation compound to the surface of a III ion exchange membrane and irradiating it with radiation (Japanese Patent Publication No. 38-16633), A method of attaching a sulfonic acid type polymer electrolyte and an allylamine compound to the surface of an ion exchange membrane and then irradiating and crosslinking with ionizing radiation (Japanese Patent Publication No. 51-4113), which has opposite charges on the surface of the ion exchange membrane. Dispersion system of ion exchange resin and mother polymer 371
No. 90), a sheet material made by impregnating and polymerizing polyethylene film with styrene and divinylbenzene is sandwiched between stainless steel frames, and after sulfonating one side, remove the sheet and fold it into the remaining part. Examples include chloromethylation and amination methods (US Pat. No. 3,562,139).

[Problem that the invention seeks to solve]

However, in the bipolar family obtained by the above-mentioned method, when trying to decompose water, a voltage much higher than the theoretical electrolysis voltage of water is applied, which requires high power consumption, and there are problems with bipolar membranes. There was also a misunderstanding that it was not easy to manufacture.

[Means for solving problems]

In view of the above-mentioned problems, the present inventors have conducted extensive research and found that a bipolar membrane with a small increase in water decomposition voltage and high water electrolysis efficiency can be easily obtained, and has therefore proposed the present invention. It's absolutely amazing. Therefore, the present invention is a method for producing a bipolar group, which is characterized in that a cation exchange group is introduced into the surface of an anion exchange membrane in advance, and then the cation exchange membrane is bonded.

The anion exchange membrane in the present invention is not particularly limited, and any known anion exchange membrane can be used.

For example, an anion exchange membrane having an ion exchange group such as a quaternary ammonium base or a pyridinium base can be used, but an anion exchange membrane having an alkali-resistant quaternary ammonium base is desirable for bipolar applications. Also,
Anion exchange membranes are of polymer type, condensation type, homogeneous type, and non-uniform type.

Alternatively, any kind or model of the anion exchange membrane may be used depending on the presence or absence of a reinforcing core/material and the manufacturing method.

Next, as a method for previously introducing a cation exchange group onto the surface of an anion exchange membrane, there are generally the following two methods. That is, a cation exchange group is introduced in advance into a membrane-like polymer material having a functional group that can be converted into an anion exchange group or a functional group that can be converted into a cation exchange group. A method in which a cation exchange group is first introduced on the surface of the membrane polymer and then an anion exchange group is introduced inside the membrane polymer. There is a method of introducing an anion exchange group into a material and then introducing a cation exchange group onto its surface.

In the method (1) above, for example, chloromethylstyrene,
A film-like polymer whose main component is divinylbenzenestyrene is prepared, and its surface is first sulfonated with, for example, sulfuric acid to introduce cation exchange groups, and then the chloromethyl groups present inside are reacted with trimethylamine. Then, a quaternary ammonium base is introduced as an anion exchange group, and a cation exchange group is previously introduced onto the surface of the anion exchange membrane of the present invention.

In method (2) above, for example, a film-like polymer whose main components are 4-vinylpyridine, divinylbenzene, and styrene is prepared, and pyridyl groups are converted into pyridinium groups, which are quaternary salts, using methyl iodide. Then, a cation exchange group is introduced into the benzene ring of styrene on the surface of the membrane using sulfuric acid, thereby introducing a cation exchange group into the surface of the anion exchange membrane in advance.

The cation exchange group may be introduced on both sides of the anion exchange membrane, but it is preferable to introduce the cation exchange group on one side, and it is necessary to introduce the cation exchange group on at least the interface with the cation exchange membrane. Furthermore, if the thickness of the cation exchange base layer placed on the surface of the anion exchange membrane becomes too thick, it becomes an amphoteric membrane or a cation exchange membrane, and if it is too thin, the resulting bipolar membrane cannot exhibit its voltage reduction effect. Therefore, the thickness of the cation exchange base layer on the surface of the anion exchange membrane is generally suitable for O,OX to 10 μm, preferably 0.1 to 5 μm.
It is an inn.

The cation exchange membrane to be joined in the present invention is not particularly limited, and any known cation exchange membrane can be used.

For example, an ion exchange membrane having an ion exchange group such as a sulfonic acid group, a carboxylic acid group, or an M acid ester group can be used. In addition, cation exchange membranes are of polymer type, condensation type, and uniform type.

Any type of cation exchange membrane may be used, such as a non-uniform type, the presence or absence of a reinforcing core material, and the type and type of cation exchange membrane derived from the manufacturing method.

In the present invention, a known method is employed to bond the anion exchange membrane and the cation exchange membrane, each of which has a cation exchange group introduced into its surface in advance, but generally an adhesive is used. . If you use such an adhesive, you get it! A hydrophilic adhesive is preferred in order not to increase the electrical resistance of the ls (joint portion). Examples of hydrophilic adhesives include starch and alginic acid.

Glue, gum arabic, gelatin, glycerinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylic acid, polyethylene oxide, polymaleic acid copolymer, polyethyleneimine, copolymer of styrene sulfone and acrylic acid, M, M, H-trimethylammonium ethyl, copolymer of acrylate and acrylic acid, 2-acrylamide-2-methylpropanesulfone=
These include copolymerized electrokinetics of CinnaF and acrylic acid. Furthermore, in order to firmly adhere the anion exchange membrane and the cation exchange membrane, it is preferable that the joint portion has a three-dimensional network structure. Therefore, in order to form such a three-dimensional network structure, the cross-linking agent is used as an adhesive as described above! − is selected and used as appropriate.

The crosslinking agent is generally a reactive methylol group.

A/Compounds having a plurality of functional groups such as mexyl group, anono group, aldehyde group, dimexy group, haloalkyl group, or compounds having two or more of the above functional groups are used, for example, trimethyl a- methylated acid, ethylene glycol, glycerin, maleic acid* "e p-'tal L 7-talic anhydride, pyromellitic anhydride, ethylenediamine, diethylene)tuamine, meta-7aa nylenediamine, glutaraldehyde, formaldehyde, epichlorohydrin, bis71 Nol A diglycidyl ether,
1.4-dibromobutane.

1,6-dibromohexane, etc. Note that the method of bonding an anion exchange membrane and a cation exchange membrane using such an adhesive is generally to sandwich the adhesive between the anion exchange membrane and the cation exchange membrane and press, or as necessary. Measures are taken to heat the material. At this time, the anion exchange membrane and the anion exchange membrane may be in a water-containing state, a solvent-containing state, or a dry state, respectively.

[Effect]

Although the mechanism of action of the present invention is not yet fully clear, it is possible to introduce cation exchange groups onto the surface of the anion exchange membrane! Therefore, the boundaries between the cation exchange groups and anion exchange groups of the bipolar membrane obtained by joining are quite close or mixed, making it difficult to form a non-conductive water layer at the boundary. Therefore, it is presumed that the voltage during water splitting becomes lower. On the other hand, in a conventional bi-pouch membrane in which a cation exchange membrane and an anion exchange membrane are bonded together, a layer of water is likely to form at the interface of the joint, which is thought to increase the voltage during water splitting.

〔effect〕

As explained above, according to the manufacturing method of the present invention, a bipolar membrane with a low water decomposition voltage can be obtained in a container. Therefore, water electrolysis using the bipolar membrane of the present invention contributes to the effect that the electric power consumption can be significantly reduced. Particularly recently, salt, which is the product of neutralization between acid and alkali, is being dumped into the open ocean due to stricter wastewater regulations, and there is a strong desire to regenerate this salt into acid and alkali once again. The bipolar membrane of the present invention is extremely useful in methods for producing salts and alkalis from aqueous solutions of such salts.

(Example) The present invention will be described below with reference to Examples, but the present invention is not limited thereto. The properties of the bipolar membrane were measured as follows. That is, 1 IM-hydrochloric acid aqueous solution was placed on the cation exchange membrane side of the bipolar membrane with an effective membrane area of 1001.
QQd, IM-sodium hydroxide was placed on the anion exchange membrane side, and at a current density of IOA/(lIl', 4~
After applying electricity for 16 hours, by measuring the amount of each 5IIi, the current efficiency of hydrogen iodine and hydroxide ions (ηII, yo
u) and current efficiency of chloride ion and sodium ion (io4
ηMa) was determined.◎ Also, the voltage drop due to the bipolar membrane at that time was also measured.

Example 1 Vinylbenzyl chloride 50s, 35 parts of styrene, 15 parts of divinylbenzene with a purity of 50%.

2 parts of benzoyl peroxide, 2 parts of styrene oxide and 5s of acrylonitrile-butadiene rubber
A viscous polymer solution was prepared consisting of: This polymer solution was placed between glass plates at 70°C in a nitrogen atmosphere for 1 hour.
A polymer film was obtained by heating and polymerizing for 6 hours. Next, this polymer membrane was immersed in 96% sulfuric acid at 60° C. for a predetermined time to introduce sulfonic acid groups onto the surface of the membrane. Furthermore, in a mixed aqueous solution of 7 tons of trimethylene
C. for one day to introduce anion exchange groups into the membrane, thereby obtaining an anion exchange membrane. In addition, for a comparative example, an anion exchange membrane was obtained which was treated only with trimethylamine without introducing sulfonic acid groups into the surface of the polymer membrane.

A mixture consisting of equal amounts of 5% polyvinyl alcohol and 5% glutaraldehyde was applied between each of the 2m type anion exchange membranes obtained above and the cation exchange membrane (aM-1) manufactured by Tokuyama Soda Co., Ltd., Heat pressing was performed at 50° C. for 1 hour to bond and form a bipolar film. Table 1 shows the performance of the obtained bipolar membranes of Examples and Comparative Examples.

From the above Table 1, it can be seen that water splitting occurs at low voltages in the bipolar membranes of Examples, which were manufactured by using anion exchange membranes whose surfaces were sulfonated.

Example 2 Styrene 85 parts, 50% purity divinylbenzene 1
A 100 μm thick polyethylene film was immersed in a mixed solution of 5 parts of benzoyl peroxide, 2 parts of benzoyl peroxide, and 20 parts of dioctyl phthalate at 60°C for 1 hour, then covered on both sides with vinylon film, and then placed in an autoclave. Polymerization was performed at 80° C. for 10 hours to obtain a film-like polymer. Thereafter, sulfonation was performed at 40° C. for 1 hour in a mixed solution of chlorosulfonic acid and sulfuric acid to obtain a cation exchange membrane.

This cation exchange membrane and the two types of anion exchange membranes manufactured in Example 1 were mixed with a mixed solution consisting of equal amounts of 5% polyvinyl alcohol and 5% maleic acid aqueous solution as a surrounding agent. The two films were sandwiched and bonded with a heating press at 90° C. for 1 hour to obtain bipolar films. Table 2 shows the performance of the obtained bipolar membranes of Examples and Comparative Examples.

Table 2

Claims (1)

[Claims] 1) A method for producing a bipolar membrane, which comprises introducing a cation exchange group into the surface of the anion exchange membrane in advance and then bonding the cation exchange membrane.