JP3026264B1 - Gas diffusion electrode-edge material assembly and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a gas diffusion electrode-edge material assembly capable of forming a large-sized oxygen cathode having good handleability as an electrode plate, easy sealing, and no liquid leakage, and a method for manufacturing the same. SOLUTION: A gas diffusion electrode-edge material assembly obtained by joining a metal edge material to an outer peripheral portion of the gas diffusion electrode. As the metal rim material, use is made of a metal selected from the group consisting of silver, silver alloy, gold, platinum, and palladium, or a material obtained by coating the selected metal with nickel or a nickel-based alloy material. A metal rim is brought into contact with an outer peripheral portion of a gas diffusion electrode formed by laminating a reaction layer sheet, a gas supply layer sheet, and a current collector sheet, and the reaction layer sheet and / or the gas supply layer sheet are rimmed. The material is hot-pressed at a temperature of 400 ° C. or lower and a pressing pressure of 5 kg / cm ² or higher and the edge material is bonded to a gas diffusion electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas diffusion electrode-edge material assembly and a method for producing the same, and more particularly, to a gas diffusion electrode used for salt electrolysis and the like, when a gas diffusion electrode is attached to an electrode pan, a power supply function and a liquid supply operation. The present invention relates to a gas diffusion electrode-edge material assembly capable of improving a sealing action and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the salt electrolysis industry, when a gas diffusion electrode is used for an oxygen cathode, the gas diffusion electrode is sandwiched together with a packing in an electrolytic cell frame to prevent leakage of the electrolyte and decomposition gas from the cathode portion. Was. However, in a practical electrolytic cell, the cathode is
It becomes a large electrode plate of 1.2 mx 2.4 m. If the size of the electrode plate is larger than 1 m ² , it is practically difficult to make a single piece, and the gas diffusion electrode has low mechanical strength and is easily deformed due to its own weight, making it difficult to handle. Turned out to happen.

[0003]

Therefore, when selecting a method of attaching a plurality of small divided electrode plates to the electrode pan, for example, a net of a current collector is protruded around the gas diffusion electrode, and the laser is connected to the electrode pan with a laser. We are studying a structure in which a sealing material is filled around the gas diffusion electrode from above the welded net by welding. However, even if such a method is adopted, there is no seal material that exhibits a long-term stable action in high-temperature, high-concentration caustic soda, which is an electrolytic condition, so that liquid leakage will inevitably occur during long-term operation. Occurs. If liquid leakage occurs, the electrolytic performance will be reduced. Not only that,
It also causes the life of the electrode to be shortened. In order to eliminate this liquid leakage, it has been desired to realize a means which is firmly joined to the gas diffusion electrode and which facilitates current collection and sealing. An object of the present invention is to provide a gas diffusion electrode assembly which has good handleability as an electrode plate, is easy to seal, and has no liquid leakage, and a method for manufacturing the same.

[0004]

SUMMARY OF THE INVENTION The present inventor has proposed a fluorine-containing
An edge material made of a metal such as silver is brought into contact with an outer peripheral portion of the gas diffusion electrode to be sealed using a fat, and a temperature not lower than the melting point of the fluororesin used and not higher than 400 ° C., and a pressing pressure of 5 kg / cm ^{2 is used.} When heated and pressurized under the above conditions, the contact portion between the rim material and the gas diffusion electrode is firmly joined, the resulting assembly of the gas diffusion electrode has good handling properties, and the gas diffusion electrode, the electrolytic cell and No liquid leakage from the seal part. The joined body of the gas diffusion electrodes is structurally a gas diffusion electrode with a rim material, and when the rim material is of a shape surrounded by a frame, the gas diffusion electrode becomes a framed gas diffusion electrode, and It is easy to eliminate liquid leakage from the seal portion with the tank.

That is, the present invention has achieved the above object by the following means. (1) A gas diffusion electrode-edge material assembly obtained by bonding a metal edge material to an outer peripheral portion of the gas diffusion electrode. (2) The metal rim should be made of a metal selected from the group consisting of silver, silver alloy, gold, platinum, and palladium, or be a material obtained by coating the selected metal with nickel or a nickel alloy material The gas diffusion electrode-edge material assembly according to the above (1), which is characterized in that: (3) A metal edge material is brought into contact with an outer peripheral portion of a gas diffusion electrode using a fluororesin, which is formed by laminating a reaction layer sheet, a gas supply layer sheet, and a current collector sheet, and the reaction layer sheet and / or the gas supply layer sheet and the edge material and the fluoride <br/> containing resin melting point or higher, 400 ° C. or less of the temperature, the press pressure 5k
A method for producing a gas diffusion electrode-edge material assembly, wherein the edge material is joined to the gas diffusion electrode by hot pressing under a condition of g / cm ² or more.

[0006] In the gas diffusion electrode-edge material assembly (hereinafter sometimes also referred to as "gas diffusion electrode assembly") according to the present invention, the range covered by the metal edge material is the outer peripheral portion of the gas diffusion electrode. This is because, when the gas diffusion electrode is supported by the frame of the electrolytic cell, only the outer peripheral portion thereof comes into contact with the frame of the electrolytic cell, and a force is applied to that portion. For this reason, the metal edge material is usually formed in a frame shape corresponding to the outer peripheral portion of the gas diffusion electrode. However, due to structural reasons, for example,
Only two of the four sides may be used. In addition, when the shape of the metal rim is not limited to a frame-like size that abuts on the outer peripheral portion of the gas diffusion electrode, and is set to a size protruding outward from an outer end of the gas diffusion electrode, the overhang is required. If it is made to abut on the frame of the electrolytic cell at the portion, the force at the time of fixing to the electrolytic cell can be received by the overhang portion, and the force is applied to the outer peripheral portion of the gas diffusion electrode, that is, the gas diffusion electrode itself. The gas diffusion electrode can be prevented from being hung, and the problem of destroying the gas diffusion electrode which is weak in strength is reduced. Furthermore, since the metal rim covers the central portion of the gas diffusion electrode, the electrolytic surface becomes narrower. Therefore, it is preferable that the portion overlapping with the gas diffusion electrode be as small as possible, so that the ratio to the area of the gas diffusion electrode is reduced. It is preferred that

[0007]

Embodiments of the present invention will be described below, but the present invention is not limited thereto. In the embodiment of the present invention, a conventional ordinary gas diffusion electrode 1 using a silver mesh as a current collector can be applied as a form thereof. Hereinafter, description will be made with reference to the drawings. FIG. 2 is a diagram showing a cross section of a conventional gas diffusion electrode 1 using a silver net as a current collector. A silver mesh 4 is interposed between the upper and lower gas supply layers 3a and 3b having the same ends, and the gas supply layers 3a and 3b are provided on the upper surface of the gas supply layer 3a.
The reaction layer 2 is laminated by aligning the end with b. Silver net 4
Is protruded outward from one end of the gas supply layers 3a and 3b with a width of 5 mm. FIG. 1 is a cross-sectional view of one example of the gas diffusion electrode-edge material assembly of the present invention. The same gas diffusion electrode 1 as the gas diffusion electrode 1 shown in FIG. 2 is used, and the silver mesh 4 in a range protruding from one end of the gas supply layer 3 is formed.
It is bent so as to overlap the reaction layer 2.

In the present invention, the edge material 5 is used. Edge material 5
For example, 10 mm in length and width from the size of the gas diffusion electrode 1
Prepare a 0.2mm thick silver plate and expand the gas in the middle.
Open a window about 10 mm smaller than the vertical and horizontal sides of the scattering electrode 1
You. As shown in FIG. 1, this edge material 5 with the window opened
Part (inner part) overlaps the bent silver mesh 4
And put it at 250 ° C where it overlaps
Surface pressure 100kg / cm ^TwoHot press with a frame
Is joined to the gas diffusion electrode 1. I understand from this
Thus, in the case of FIG. 1, the outer peripheral portion 8 has a width of 5 mm,
Bonding is performed at this portion. Just over the reaction layer 2
It corresponds to the portion of the silver net 4 that is bent like this.

The current collector of the gas diffusion electrode 1 is preferably a silver mesh, a porous silver material, a silver-plated nickel mesh or a silver-plated nickel porous material. The silver plate used for the edge material is 0.05 to 0.3 mm
Good thickness. The material is desirably pure silver, but various silver alloys can be used under high temperature and high pressure. Gold, platinum, palladium and the like can also be used as long as they are corrosion-resistant and extensible metals. In addition, silver or nickel plating on nickel or nickel base alloy material, and further in the form of clad material,
A silver nickel clad plate may be used. That is, if a soft silver mesh or the like is interposed on the bonding surface with the gas diffusion electrode 1, the bonding can be performed. The hot pressing conditions are preferably such that the temperature ranges from the melting temperature of the used fluororesin to 400 ° C. or less. 20
If the temperature is lower than 0 ° C., the bonding strength is small, and if the temperature is higher than 400 ° C., decomposition of PTFE starts, which is not preferable. If the pressure is low, the joining force is small, so the larger the better. Practical pressure is 20kg / cm ² ~100kg / cm ² approximately. The joining edge material 5 is a metal frame, that is, the gas diffusion electrode 1.
May be formed in a frame shape on the entire circumference, or may be joined as a current collector to a part of the outer periphery of the gas diffusion electrode. Such a joined body can be firmly fixed by forming a welded portion 10 by laser welding to the cathode pan, that is, the electrode pan 8.
FIG. 7 is a cross-sectional view of an electrode assembly in which such a joined body is fixed to the cathode pan 9 by welding at a welding portion 10. The above-mentioned joining can be performed by means such as resistance compression bonding, heat compression bonding, and caulking in addition to laser welding.

[0010]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1 Hydrophobic carbon black (denka black, average particle size: 390 angstroms, manufactured by Denki Kagaku Kogyo) was added to 200 parts (weight, the same applies hereinafter) of 4% triton (surfactant).
Add parts and stir to disperse. The carbon black dispersion was dispersed for 5 minutes by an ultrasonic disperser (500 W, manufactured by Branson) while cooling with water. As a result, the average particle size was 1.6 microns. This dispersion is mixed with silver colloid (produced by Tanaka Kikinzoku Co., Ltd., average particle size 0.1 micron)
Add 10 parts and stir and mix. Further, 1.5 parts of PTFE dispersion D-1 (average particle size: 0.3 micron, manufactured by Daikin Industries, Ltd.) is added and mixed with stirring. 300 parts of isopropyl alcohol is added to this dispersion, self-organized, and filtered to obtain a reaction layer raw material.

A sheet in which the reaction layer 2 (see FIG. 1) and the gas supply layer 3a are laminated by a roll method is manufactured, dried at 80 ° C. for 3 hours, and the surfactant is removed by an ethanol extraction device.
After drying at 0 ° C. for 5 hours, a reaction layer gas diffusion layer bonding sheet was obtained. This reaction layer gas diffusion layer bonding sheet is 11 cm × 21
Cut into a cm rectangle. A gas supply layer sheet 3b similarly prepared from hydrophobic carbon black and PTFE (40%) is also cut to the same size. Wire diameter 0.1 mm, 5
A silver mesh of 0 mesh is cut into a rectangle of 12 cm × 22 cm. As shown in FIG. 1, the reaction layer gas diffusion layer bonding sheet, the silver mesh 4, and the gas supply layer sheet 3b are stacked in this order, and 50 k
The gas diffusion electrode 1 was obtained by pressing at 350 ° C. for 60 seconds at g / cm ² . The silver mesh 4 around the gas diffusion electrode 1 is bent toward the reaction layer 2 side.

A rectangular silver plate having a thickness of 0.2 mm and a size of 13 cm × 23 cm is prepared.
It was cut out in a size of 0 cm × 20 cm to form a silver frame to be the edge material 5. A silver frame is superimposed on the outer peripheral portion 8 of the gas diffusion electrode 1, hot pressing is performed on the overlapped portion at a surface pressure of 100 kg / cm ² and a temperature of 260 ° C., and the silver frame as shown in the sectional views of FIGS. To obtain a bonded body of gas diffusion electrode plates. Next, as shown in FIG. 7, an electrode assembly obtained by joining the gas diffusion electrode-joint to the frame of the electrode pan 9 was obtained by laser welding to the electrode pan 9. It was confirmed that the electrode assembly was capable of performing stable electrolysis without liquid leakage. Salt electrolysis was performed using this electrode assembly as an oxygen cathode. 1.9 at 90 ° C., 32% NaOH, 30 A / dm ²
An electrolytic cell voltage of 7 V was obtained.

Embodiment 2 FIG. 3 is a sectional view showing an example of a joined body of gas diffusion electrode plates according to the present invention. In Example 1, after the gas diffusion electrode 1 was hot-pressed, the gas diffusion electrode 1 was joined to a silver plate 5 (here, "silver plate 5" because a "silver plate" was used as an edge material). As shown in FIG. 3, the reaction layer gas supply layer joining sheet, the silver mesh 4, the silver plate 5, and the gas supply layer sheet 3b are superimposed in this order, and pressed at 350 ° C. and 50 kg / cm ² for 60 seconds to form a silver edge material. A gas diffusion electrode assembly was obtained.
This example has a structure in which an edge material is provided between the gas supply layer sheet 3a and the gas supply layer sheet 3b.

Example 3 Using the same laminated sheet of the reaction layer gas diffusion layer bonding sheet and the gas supply layer sheet 3b as in Example 1, a 0.1 mm thick silver was formed on the outer periphery of these sheets as shown in FIG. 3-5 mm for plates 5-7
Sandwiched by width, laminated in the same manner as in Example 2, and
By pressing at 350 ° C. for 60 seconds at cm ² , a gas diffusion electrode plate assembly with edge material as shown in FIGS. 5 and 6 was obtained. FIG. 5 is a plan view of the obtained gas diffusion electrode assembly with silver edges as viewed from the reaction layer side. FIG. 6 is a sectional view thereof. The gas-diffusion electrode assembly with a silver edge obtained in Example 3 had higher breaking strength than Examples 1 and 2. Here, the silver plate 5 is interposed between the reaction layer gas diffusion layer joining sheet and the gas supply layer sheet 3b, but actually, any one of the surface of the reaction layer 2 and the surface of the gas supply layer sheet 3b is provided. It may be superimposed on the surface.

[0016]

According to the present invention, the gas diffusion electrode and the metal edge material can be firmly joined without liquid leakage and gas leakage at the outer peripheral portion of the gas diffusion electrode. It has become possible to carry out through the edge material. as a result,
Normal metal processing becomes possible, and it can be joined to the electrode pan or the power feeder joined to the electrolytic cell by laser welding, resistance crimping, heat crimping, caulking, or the like. Moreover, even after the electrolysis is carried out for a long period of time after being mounted in the electrolytic cell, an extremely stable oxygen cathode having a low power supply resistance and no liquid leakage can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one example of a joined body of gas diffusion electrode plates of the present invention.

FIG. 2 shows a cross-sectional view of a conventional gas diffusion electrode.

FIG. 3 is a cross-sectional view of a gas diffusion electrode plate-edge material assembly of Example 2.

FIG. 4 is a cross-sectional view of a gas diffusion electrode plate / edge material assembly according to a third embodiment.

FIG. 5 shows a plan view of a gas diffusion electrode assembly with a silver border.

FIG. 6 is a cross-sectional view of the gas diffusion electrode assembly with a silver rim material of FIG. 5;

FIG. 7 is a cross-sectional view of an electrode assembly obtained by welding and bonding a gas diffusion electrode plate-edge material assembly to an electrode pan.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas diffusion electrode 2 Reaction layer 3 Gas supply layer 4 Silver mesh 5 Edge material (silver plate) 6 Edge material (silver plate) 7 Edge material (silver plate) 8 Outer peripheral part 9 Electrode pan (cathode pan) 10 Welded part

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Choichi Furiya 2-14 Nakamuracho, Kofu City, Yamanashi Prefecture (56) References JP-A-7-207482 (JP, A) JP-A-2-30784 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C25B 1/00-15/08

Claims (3)

(57) [Claims] 1. A gas diffusion electrode / edge material assembly obtained by joining a metal edge material to an outer peripheral portion of a gas diffusion electrode. 2. The metal rim is made of a metal selected from the group consisting of silver, silver alloy, gold, platinum, and palladium, or a metal or nickel-based alloy coated with the selected metal. The gas diffusion electrode-edge material assembly according to claim 1, wherein: 3. A metal edge member is brought into contact with an outer peripheral portion of a gas diffusion electrode using a fluororesin, which is formed by laminating a reaction layer sheet, a gas supply layer sheet, and a current collector sheet. Layer sheet and / or gas supply layer sheet and edge material
The gas diffusion electrode is bonded to the gas diffusion electrode by hot pressing at a temperature not lower than the melting point of the fluororesin, not higher than 400 ° C. and a pressing pressure of 5 kg / cm ² or higher. Manufacturing method of joined body.