JPS6026497B2 - Manufacturing method of cation exchange membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing cation-exchanged pus.

Electrolysis of an aqueous alkali metal chloride solution using a cation exchange membrane has overcome the drawbacks of the conventional techniques such as the mercury method and the corneal membrane method, and has developed as a new energy-saving technology.

There is no risk of pollution, product purity is excellent, and the total energy cost (combined electricity and steam) is said to already exceed the mercury method and diaphragm method. However, although they are energy-saving types, electricity costs account for a large proportion of manufacturing costs, and the need for technological development to reduce power consumption is increasing as energy costs rise. Several attempts have been made to lower the electrolysis voltage in electrolysis methods using intestinal ion exchange membranes. Reducing the distance between the anode and cathode and reducing the amount of liquid and gas present in that area is considered an effective method for lowering the voltage. 50-10
This is disclosed in Ban No. 99 Publication. However, in these methods, although the distance between the anode and the intestinal ion exchange membrane is shortened, the distance between the cathode and the intestinal ion exchange membrane is still large and the voltage drop is insufficient. Hakama Kaisho 54-147877
The publication proposes mechanically bringing the negative and positive electrodes into close contact with the cation exchange membrane using the force of a spring, etc.
Due to the manufacturing precision of the electrodes and the standpoint of high protection, the distance between the electrodes cannot be made too small, and the voltage drop is insufficient.

In addition, as electrolyzers in which the inter-electrode distance is further shortened, there are Japanese Patent Laid-Open Nos. 52-78788 and 53-52597.

For these, devices have been proposed in which an anode is embedded in one surface of the membrane and a cathode is embedded in the other surface. In this method, the distance between the electrodes is only the thickness of the cation exchange membrane, so if this method is applied to the electrolysis of alkali metal chloride salts, although a voltage drop can certainly be expected, there are the following disadvantages: be. 1. The electrolytic voltage decreases in a range where the current density is low, but as the current density increases, it tends to increase due to m-loss of the electrode itself.

2 For this reason, it is necessary to use an expensive device as a so-called current collector for the current supply device to both electrodes.

3. If the contact between the current collector and the electrode is not ensured, the contact resistance will increase, so it is necessary to bring the current collector and the electrode into contact using mechanical force such as a spring.

This mechanical force tends to damage the membrane. 4. Difficult to apply to large industrial electrolytic cells. 5. If either the electrode or membrane is damaged, it will be impossible to continue electrolysis.

6 The current efficiency tends to decrease as the current density increases, and at the anode, water decomposition tends to occur due to insufficient supply of alkali metal chloride, and the oxygen gas content in the chlorine gas increases compared to the conventional method. .

In other words, this method has great promise in reducing voltage drops, but there are many mechanical and equipment problems that need to be solved as mentioned above, and it is difficult to achieve stability in operation and equipment, which is the most important industrially. This is problematic and, in practice, extremely difficult.

Further, Tokukan Sho 55-164086 discloses a method in which a cathode is fixed to the cathode side surface of a cation exchange membrane and electricity is applied to the cathode to perform electrolysis. This method is improved in several respects compared to the method in which electrodes are fixed to the cathode and anode surfaces, but in order to supply current to the cathode, a porous support and an elastic laminate are required. Requires a device to ensure contact between the current collector and the cathode and the current collector;
The industrially important problems mentioned above have hardly been solved. In other words, in electrolysis using a conventional electrolytic cell with an anode and a cathode installed with an intestinal ion exchange membrane in between, the structure of the cell is simple, so the operating conditions, operation, and maintenance are easy and the operation is safe. Although it has excellent properties, it has the disadvantage of high fog* pressure due to the liquid and bubbles existing between the electrode and the membrane.

On the other hand, when the positive and negative electrodes are fixed to the membrane and electrolysis is carried out by passing current through the fixed electrodes, a large or medium voltage reduction can be expected. Even if the above-mentioned problems are solved, the dew tank price, operation, and maintenance costs are higher than the conventional method, so it is not an economically advantageous method. hard. One of the inventors of the present invention has made extensive studies to develop an industrially and economically superior electrolysis method that eliminates the drawbacks of both and has only the advantages of both, and has developed They discovered that a significant reduction in electrolytic voltage could be achieved by using a membrane with fixed metals in a conventional electrolytic cell, and completed and proposed the invention.

According to such a method, the durability of the chemical plating layer applied to the intestinal ion exchange membrane is an important requirement.

Generally, cation exchange membranes for salt electrolysis are designed so that the carboxylic acid base layer faces the cathode side from the viewpoint of current efficiency. However, when such a carboxylic acid base layer is chemically plated, some problems arise in its durability. Therefore, the inventors of the present invention have continued intensive studies to solve this problem, and as a result, have achieved the object of the present invention. That is, in a cation exchange membrane having a carboxylic acid base layer on the cathode side, a layer containing a sulfonic acid group is formed on the layer to a thickness of 0.01 μm to 5 μm, and then a layer containing a sulfonic acid group is formed on the layer. The present invention provides a method for manufacturing an intestinal ion exchange membrane with a durable metal bonded to it by chemical plating.

Examples of monomers used in the production of the cation exchange membrane used in the present invention include those represented by the following general formula.

[However, R = CF3, -CF2-○-CF o n = 0 or 1 to 5 m; 0 or 1 o = 0 or l p = 1 to 6 x = S02F2, S02CI, COOR, (R, = 1 to
5 alkyl group) CN, COF] Specific examples of the polymer used in the production of the intestinal ion exchange membrane produced using the above monomer include the following polymers.

(Group A) The polymer shown in Group A is a perfluorocarbon polymer having a group that can become a sulfonic acid group, and has an exchange group capacity of 0.5 to 1. enemy heg
/g dry resin can be used.

The polymer shown in Group B is a perfluorocarbon polymer having a group that can become a carboxylic acid group, and has an exchange group capacity of 0.6 to 1. shoes eg/
A range of dry resins can be used.

The cation exchange membrane used in the present invention is, for example, I
After laminating a film of the polymer shown in Group A and a film shown in Group B, they were hydrolyzed and the carboxylic acid groups in a predetermined layer of the carboxylic acid base layer were converted with iodine.
Processed as 2nd prize.

2. Apply the polymer shown in Group A on the film of the polymer shown in Group B, or laminate the film together.

3 After hydrolyzing a film of the polymer shown in Group A, converting the sulfonic acid groups into sulfonyl halide in a predetermined layer, then hydrolyzing the sulfonyl halide layer into a predetermined layer, and further oxidizing. agent or reduction treatment.

It can be obtained by means such as.

Of course, the cation exchange membranes used in the present invention are not limited to these.

The cation exchange membrane used in the present invention is 50 μm to 5 μm.
It is generally used with a thickness of 00A, and an appropriate thickness is selected in consideration of specific conductivity and current efficiency. The thickness of the sulfonic acid base layer formed on the carboxylic acid base layer varies depending on the membrane used, but it should be within a range that does not reduce current efficiency. The range is 0.01mm to 5mm. The metal to be fixed to the sulfonic acid base layer formed on the carboxylic acid base layer of the intestinal ion exchange membrane is not particularly limited as long as it has sufficient catalytic activity for the cathode reaction, but platinum, palladium, etc. are usually used. Platinum group metals such as ruthenium and iridium and nickel or mixtures thereof are used.

These metals are fixed to the membrane by chemical plating. However, the chemical plating method itself is a normal method and there are no particular restrictions. For example, a metal salt solution to be plated is placed on the cathode side of a cation exchange membrane, and a reducing solution is placed on the anode side to control the permeation rate into the membrane. Method of plating using difference (Samurai Seki Sho 55-So No. 934) The membrane is immersed in a metal salt solution, the pus is impregnated with the metal salt, and then immersed in a reducing agent to improve the membrane surface. A method of precipitating a metal, a method of using a non-electrostatic coating liquid, etc. can be selected as appropriate, and the above methods may be combined. Further, the electrical conductivity of the fixed electrode should be IQ-1 clause-1 or higher to achieve the purpose, and this conductivity can be easily achieved by chemical plating. Some of the effects will be specifically shown below.

Note that the present invention is not limited in any way by these specific examples. Example 1 The monomer with 1,1,2-trichloro-1,2,2-
After obtaining a copolymer using perfluoropropionyl peroxide as an initiator in trifluoroethane,
It was molded into a film with a size of 0.

Next, 2 skin t% KOH-methanol (weight ratio = 1/1)
By hydrolyzing at 90 pm, the exchange capacity is 0.
．． An intestinal ion exchange membrane of 91 meg/g dry resin was obtained. The membrane was treated with hydrochloric acid to convert S03K to S03 day. The membrane thus treated was treated with phosphorus pentachloride-phosphorus oxychloride (
React only on one side in 1/1 weight ratio), SQH 150
A film of S02CIIOO was obtained.

Next, only the S02CI side of the film was coated with 2 K% KOH.
- methanol (weight ratio 1/1) to convert the layer of S02C1 to S03H' with a thickness of 0.5〃. Next
Treated with hydrogen uride at 85°C for 5 days, then 2 skin t%
- S02CI in the film was converted to COOK by hydrolysis with methanol (1/1 weight ratio).

Next, the surface of the S03K layer on the COOK layer was impregnated with platinum salt, and then reduced using NaB, and then dimethylamine borane (hereinafter referred to as DMAB) was impregnated with platinum salt.

) was chemically plated with a platinum electroless finishing liquid.
Titanium expanded metal coated with ruthenium oxide was used as the anode, and expanded metal made of iron was used as the cathode. Two legs were used between the intestinal cathodes, and the level at which fresh salt water was extracted from the anode chamber was set 20 arcs higher than the liquid level in the cathode chamber so that the platinum-fixed surface of the membrane was in contact with the cathode. Saturated salt solution in the anode chamber and 34w of caustic soda in the cathode chamber.
Electrolytic density 3 at 90qo while controlling to t%
Electrolyzed at ship/dm2. Voltage after 3 months of operation is 3.2V
Current efficiency was 93%.

The cell was disassembled, the intestinal ion exchange membrane was taken out, and the chemically plated layer was examined, but no ``peeling'' was observed.
Comparative Example 1 Instead of the cation exchange membrane used in Example 1, a cation exchange membrane without an SQK layer was used on the COOK layer, and chemical plating was applied in the same manner as in Example 1. I drove.

After three months of operation, the voltage was 3.4V and the current efficiency was 93%.

When the cell was disassembled, the cation exchange membrane was taken out, and the chemically plated layer was examined, some ``peeling'' had occurred. Comparative Example 2 The cation exchange membrane used in Example 1 was operated in the same manner as in Example 1 without chemical plating.

After three months of continuous operation, the voltage was 3.6V and the current efficiency was 93%.

Example 2 Tetrafluoroethylene and CF2=CFOCF2CF(CF3)OCF2CF2C
OOCH3 was copolymerized in 1,1,2-trichloro-1,2,2-trifluoroethane using perfluoropropionyl peroxide as an initiator in a stainless steel autoclave.

The obtained product was press-molded at 250 qo to obtain a transparent raw film (1) of 200 qo. This film-like raw film (1) was mixed with 10% KOH-methanol (50/50).
After hydrolysis in V/V), the carponate content was determined to be 1.2 heg/g dry resin by titration. These two raw films (1) were sandwiched between acrylic resin frames using Teflon packing, and each frame was coated with 2% Na.
It was immersed in an OH aqueous solution at room temperature, and only the surface layer on one side was hydrolyzed. This film is referred to as a raw film (0).

When Harakoshi (0) was stained with crystal violet, about 1.0 micron of the surface layer on one side was stained.

The source membrane (D) was immersed in IN-AgN03 aqueous solution and one side 1
．． After converting -COONa present in the layer of Mt.

A film-like material in which the 1.0〃 layer on one side was substituted with Ag salt was reacted at 180° C. for 1 hour in the presence of 12. After washing with methanol and drying, examining the surface infrared spectrum reveals -COOAg 1
The peak at 650-1 completely disappeared, and the peak at 91 at CF21
A new peak of 0-1 appeared.

This film is referred to as a raw film (m). The raw film (handled) was immersed in a suspension in which Zn powder and acetic acid steel had been reacted in anhydrous dimethyl sulfoxide under a N2 atmosphere to form a Zn-Cu couple, and S02 was bubbled therein. The reaction was carried out at a temperature of 400°C for 6 hours.

After the reaction, the membrane was taken out and soaked in methanol in which CI2 was dissolved at 30q0 for 1 hour. After thoroughly washing with methanol, drying and examining the surface infrared spectrum, -CF21 9
The peak of 10g-, almost disappeared, and a new peak of 1420
A peak that appeared to be due to CF2S02CI appeared on the skin.

This film is referred to as a raw film (W).

The raw film (W) was diluted with 10% KOH-methanol (50/50V
/V) at 60° C. for 1 hour for hydrolysis.

Next, the S03K layer on the COOK layer was impregnated with platinum salt, and then reduced using a NaB ratio, and then chemically plated with a platinum electroless finishing solution containing DMAB. Titanium expanded metal coated with ruthenium oxide was used as the anode, and expanded metal made of iron was used as the cathode.

There was a gap between the anode and cathode, and the level of fresh salt water drawn from the anode chamber was set 2 times higher than the liquid level in the cathode chamber so that the platinum-fixed surface of the membrane was in contact with the cathode. While controlling the saturated saline solution in the anode chamber and the caustic soda in the cathode chamber to 32%, electrolysis was carried out at 90 qo and a current density of 3 M/dm2. After 3 months of operation, the electric reed is 3.4V and the current efficiency is 95%.
Met.

The cell was disassembled, the cation exchange membrane was taken out, and the chemically plated layer was examined, but no peeling was found. Comparative Example 3 Instead of the cation exchange membrane used in Example 2, an intestinal ion exchange membrane without an SQK layer was used on the COOK layer, and chemical plating was performed in the same manner as in Example 2. I drove.

After three months of continuous operation, the voltage was 3.7V and the current efficiency was 95%.

When the cell was disassembled, the intestinal ion exchange membrane was removed, and the chemically plated layer was examined, some ``peeling'' had occurred. Comparative Example 4 The cation exchange membrane used in Example 2 was operated in the same manner as in Example 2 without chemical plating.

The voltage after 3 months of operation is 4. The current efficiency was 96%.

Example 3 The same machine as in Example 1 was operated except that nickel salt was used in place of the platinum salt used in Example 1.

After three months of continuous operation, the voltage was 3.3V and the current efficiency was 93%.

Claims (1)

[Claims] 1. In a cation exchange membrane having a carboxylic acid base layer,
A method of forming a layer containing sulfonic acid groups on the layer with a thickness ranging from 0.01 μm to 5 μm, and then chemically plating the layer to fix the metal. A method for manufacturing an ion exchange membrane. 2. The method according to claim 1, wherein the cation exchange membrane having a carboxylic acid base layer is a cation exchange membrane having a multilayered structure of a carboxylic acid base layer and a sulfonic acid base layer. 3. The method according to claim 1, wherein the cation exchange membrane having a carboxylic acid base layer is a cation exchange membrane consisting only of a carboxylic acid base layer. 4. The method according to claim 1, 2 or 3, wherein the metal to be fixed is selected from platinum, palladium, ruthenium, iridium, nickel or a mixture thereof.