JPH0832962B2 - Method for manufacturing electrolysis bonded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a joined body for solid polymer electrolyte electrolysis (hereinafter referred to as SPE electrolysis).

[Conventional technology]

The electrolysis joined body is a joined thin film and a metal to be an electrode, and its importance is increasing in the SPE electrolysis method practiced in the fields of water electrolysis, hydrochloric acid or salt electrolysis. The most commonly used electrolyzing junction is a cation exchange membrane with some kind of metal layer joined to both sides.

As such an electrolysis joined body, the electrical resistance is small, the metal layer joined to the cation exchange membrane has flexibility, and the adhesiveness between the cation exchange membrane and the metal layer is good. There is a demand for properties such as exfoliation of the metal layer during electrolysis and excellent durability.

Conventionally, as a method for producing a joined body for electrolysis, Japanese Patent Publication No. 56-
As described in Japanese Patent No. 36873, a metal salt solution and a reducing agent solution are arranged through an ion exchange membrane, and the reducing agent ions are allowed to permeate the ion exchange membrane to form a metal layer on the metal salt solution side membrane. There is a way.

This method is called the permeation method, and as shown in FIG. 2, an ion exchange membrane 0 is formed at the center of the cell 03 having the inner chambers 01 and 02.
4 is placed, and the target metal salt solution is placed in the inner chamber 02.
Pour the reducing agent solution into. When the reducing agent solution is injected into the inner chamber 02, the reducing agent penetrates through the film and reaches the metal salt solution side of the inner chamber 01, a reduction reaction occurs on the metal salt solution side film surface, and metal is deposited on the film. .

After the predetermined metal layer is obtained on one side of the ion exchange membrane 04, the cell 03 is washed with water and the target metal salt solution and the reducing agent solution are injected into the opposite inner chambers 02 and 01, respectively, and the same operation is performed. A predetermined metal layer is deposited on the surface.

[Problems to be Solved by the Invention]

Table 1 shows the experimental results when platinum was bonded to the ion exchange membrane "NAF ION 117: trade name" by the method described in JP-B-56-36873.

In Table 1, No. A is the surface that was first plated, B
Shows the back side of its A side, and is a reducing agent NaBH ₄ (sodium borohydride), metal salt H ₂ PtCl ₆ · 6H ₂ O (chloroplatinic acid 6
The concentration of water salt) is in% by weight.

Regarding the adhesion of the matte to the film, it was judged that when the joined body was bent 180 ° and cracked and peeling occurred, it was poor, and when it did not occur, it was good.

In addition, using two L-type acrylic pipes (inner diameter 16 mm) having a flange with an inner diameter of 16 mm and an outer diameter of 50 mm, align the flange parts,
Nafion 11 with a diameter of 30 mm by packing silicon rubber
A methexel was assembled with 7 membranes (manufactured by Dyupon Co., Ltd.) between them.
Nafion membrane is washed with acetone and water before joining.
It was boiled in 2N-HCl for 30 minutes, washed with water, and then boiled in water for 30 minutes, stored in water, and set in a wet state before use.

From the results shown in Table 1, (1) If both sides A and B have the same plating time, B
The surface adheres more.

(2) The attachment of Pt to the periphery of the A side is particularly bad. On the other hand, the B side has relatively little unevenness.

(3) Adhesion is poor on both A and B sides.

It turned out that there is a tendency.

[Means for solving the problem]

The above problem may be due to a difference in permeability between the presence and absence of Pt when the reducing agent permeates into the membrane. When only the naphtho ion film was immersed in a 1% NaBH ₄ aqueous solution and observed, it was found that in the naphtho film without Pt bonding, a large number of bubbles, which are thought to be generated by the self-decomposition of NaBH ₄ , were attached to the entire surface. On the other hand, in the Pt-naphtho ion-bonded body, although the bubbles were intensely generated from the Pt portion, the adhesion of the bubbles to the surface was not observed. Considering these results and the tendency of Japanese Patent Publication No. 56-36873 in (1), (2), and (3) above, the reducing agent NaBH ₄ permeates due to adhesion of bubbles to the surface during A-side plating. As a result, the growth rate of the wood spatter is slow and uneven. On the other hand, when the B side is plated, the reducing agent NaBH
_{4 Although} self-decomposition is promoted and the amount of gas generated increases, bubbles do not adhere and NaBH ₄ permeation proceeds smoothly and uniformly over the entire membrane, so it is considered that the rate of growth of the rate of growth is high and the rate of variation is relatively low. .

 Based on this idea, as a method for improving the defects, (i) the reducing agent solution is stirred to remove bubbles.

(Ii) Pt thinly beforehand.

I tried two methods. In the case of (i), although the bubbles could be removed, the permeation rate of the reducing agent increased, the reaction occurred in the aqueous chloroplatinate solution, and Pt was not smeared on the film itself.

In the method of (ii), before placing the naphthaion membrane on the metexel, soak it in the reducing agent NaBH ₄ aqueous solution for 20 minutes to allow the membrane to sufficiently contain NaBH ₄ , then place it on the metexel, and place it on the A surface. The plating was carried out to such an extent that thin Pt was deposited, and after washing with water, the metal salt solution and the reducing agent solution were poured into the opposite inner chambers, respectively, and ordinary Pt was deposited on the B surface. After a predetermined metal layer is obtained on the B side, the cell is washed with water, and then a metal salt and a reducing agent solution are injected into the opposite inner chambers, respectively, and a predetermined metal layer is deposited on the A side by the same operation. Then, the metal ion was adsorbed and adsorbed on the A surface of the Ronafion membrane, and then a thin metal layer was deposited on the inner surface of the membrane by treating with a reducing agent solution. The reducing agent solution is injected into the B side with a metal salt solution, a predetermined metal layer is deposited on the B side, and then the cell is washed with water, and the metal salt and the reducing agent solution are injected into the opposite inner chambers by the same operation. Two methods, namely a method of depositing a predetermined metal layer on the A surface, were examined.

As a result, it was confirmed that a bonded body with less unevenness and good adhesion was obtained by both methods.

The present invention has been completed based on this finding. That is, in the present invention, after forming a thin metal layer on one surface of an ion exchange membrane, a metal salt solution is placed on the opposite surface of the thin metal layer across the ion exchange membrane, and reduction is performed from the thin metal surface. The agent solution is permeated to deposit a metal layer on the surface of the ion exchange membrane, and then the metal salt solution and the reducing agent solution are arranged in reverse,
This is a method for producing a junction for electrolysis, which comprises depositing a metal layer on the surface of a thin metal layer formed first by a similar operation.

In the present invention, the metal of the thin layer initially formed on the ion exchange membrane and the metal to be laminated thereafter may be the same metal or different metals.

As the metal bonded to both sides of the ion exchange membrane, Pt, I
Noble metals such as r, Rh, Ru, Pd and their alloys, Ni, Co, Cu
Base metals such as, but corrosion resistance and oxygen, hydrogen,
Precious metals that excel in chlorine generation are often used. The alloys can be joined by subjecting the mixed solution to a reduction treatment.

Examples of the reducing agent solution include alkali borohydride such as sodium borohydride, organic borohydride compounds such as dimethylamine borane, and hydrazine hydrate, sulfate or hydrochloride. Generally, sodium borohydride, which has a large reducing power, is often used.

〔Example〕

One embodiment of the present invention will be described with reference to FIG. 1, and the results are shown in Table 2.

In Table 2, No. 10 and No. 20 are the thin metal layer deposition methods to be formed first, and the Nafion 117 membrane 1 of FIG. 1 was immersed in a 1% sodium borohydride solution for 20 minutes and then the inner diameter 16
It is sandwiched between the flanges 2a and 3b of the L-shaped Metxell 2,3 of 3 mm, and the chloroplatinate H ₂ PtCl ₆ .6H ₂ O 3% aqueous solution is placed on the A side and the sodium borohydride 1% aqueous solution is placed on the B side. This is an example of using an ion-exchange membrane in which a thin metal layer is formed on one surface after injection and plating treatment for 3 minutes. On the other hand, No. 30 and No. 40 are metal thin layer deposition methods, in which tetraammine platinum (II) salt solution (50 mg / 100 ml as Pt) is brought into contact with the A surface of Nafion 117 membrane 1 and left for 2 hours to adsorb platinum. Then, this is an example of using an ion exchange membrane in which a thin layer of platinum was deposited on one side by contacting with a 0.05% aqueous solution of sodium borohydride and reducing for 2 hours.

After these treatments, the L-shaped meshel with an inner diameter of 16 mm shown in Fig. 1
Inject a 1% aqueous solution of sodium borohydride on the A side and a 3% aqueous solution of chloroplatinic acid on the B side by sandwiching it between 2 and 3 to deposit a predetermined metal layer on the B side, and then to form L-type Metexel 2, 3 was washed with water, and a 3% aqueous solution of chloroplatinic acid was injected into the A surface and a 1% aqueous solution of sodium borohydride was injected into the B surface to deposit a predetermined metal layer on the A surface.

As shown in Table 2, in all cases, a bonded body having no unevenness of plating and no cracking or peeling of the platinum layer and having excellent adhesion was obtained.

In this example, platinum was used as the thin metal layer that was first formed on the ion exchange membrane and promotes the self-decomposition of the reducing agent, but the same effect was obtained when other metals were used.

[Advantages of the Invention] According to the present invention, there can be obtained a bonded body which is free from cracks, peeling and the like and has excellent adhesiveness, and its industrial value is remarkable.

[Brief description of drawings]

FIG. 1 is a schematic view for explaining an embodiment of the present invention,
FIG. 2 is a schematic diagram for explaining one aspect of a method for producing a conventional electrolysis bonded body.

Claims (1)

[Claims] 1. A thin metal layer is formed on one surface of an ion exchange membrane, and a metal salt solution is placed on the opposite surface of the thin metal layer across the ion exchange membrane to reduce the metal thin layer surface. The agent solution is permeated to deposit the metal layer on the surface of the ion exchange membrane, and then the metal salt solution and the reducing agent solution are arranged in reverse, and the metal layer is deposited on the thin metal layer surface initially formed by the same operation. A method for producing a joined body for electrolysis, comprising: