JPH10286572A - Water electrolyzing tank - Google Patents

Abstract

(57) [Abstract] [Purpose] In water electrolysis, particularly in the production of acidic water or alkaline water by water electrolysis, the original function of acidic water or the like is impaired if a liquid leak, that is, a transfer of hydrogen ions or the like occurs. The present invention provides a water electrolyzer without such liquid leakage. A water electrolysis tank comprising an anode compartment frame, a cathode compartment frame, and a cation exchange membrane sandwiched between both frames, and a first ion exchange membrane between one of the two frames.
The sealing material 10 and the second sealing material 12 are respectively arranged between the two frames to ensure the prevention of liquid leakage by the double sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water electrolyzer having no liquid leakage, and more particularly, to a high-purity acidic water and alkali water free of metal contamination used for cleaning electronic devices such as semiconductors and liquid crystals. The present invention relates to an electrolytic cell for manufacturing.

[0002]

[Prior art and its problems] For manufacturing and cleaning electronic parts,
Conventionally, sulfuric acid, hydrofluoric acid, hydrogen peroxide, hydrochloric acid, ozone water and the like specially prepared for the use have been used.
These will be used in the future depending on the application, but they are obtained by specially refining products manufactured by the corresponding chemical processes, and the metal components mixed in from the catalyst etc. in the manufacturing process The operation is complicated to perform the removal and the like, resulting in an expensive product. Further, even if the refining operation is carefully performed, it is not always possible to sufficiently cope with the decrease in the allowable impurity amount accompanying the advancement of electronic devices, and a new alternative method is required.

[0003] As this alternative treatment liquid, there is so-called acidic water or super-acidic water. The acidic water usually has a pH of 3 or less, an oxidation-reduction potential (ORP) of 1.2 V or more, and has an oxidizing power. And has the effect of dissolving and removing metal precipitates, and has begun to be used for cleaning electronic devices. Simultaneously with the production of the acidic water, alkaline water having a pH of 10 or more and an ORP of 0 V or less is produced as a by-product in the cathode chamber of the electrolytic cell, and the use of the alkaline water for cleaning and the like has reached a practical stage.

[0004] These modified acidic water and alkaline water (electrolytically activated water or electrolytically ionic water) are used as high-purity acids,
A cleaning effect equivalent to that of a reagent such as alkali or hydrogen peroxide is obtained, and electrolytically activated water is extremely inexpensive, so that great cost savings can be achieved. During the electrolytic production of the acidic water and the alkaline water, usually, a two-chamber electrolytic cell partitioned into an anode chamber and a cathode chamber by an ion exchange membrane that is a diaphragm is used,
The acidic water and the alkaline water are produced by electrolyzing insulating water having an electric resistance of 18 MΩcm or more, which is generally called ultrapure water. The ultrapure water cannot be directly electrolyzed due to its insulating property, and uses an ion exchange membrane functioning as a solid electrolyte as an auxiliary electrolyte, and performs electrolysis by a so-called zero gap or SPE method. However, in the zero gap method in which the anode and the cathode are brought into close contact with the ion exchange membrane to perform electrolysis, hydrogen generated at the cathode may leak through the ion exchange membrane, and a phenomenon of shifting from the cathode side to the anode side may occur. The factor that the acidic water generated by the electrolysis shows the acidity is an electrolysis product of water or oxygen contained in the acidic water, and even a slight transfer of hydrogen causes the hydrogen to lower the oxidation-reduction potential of the acidic water,
There is a problem that the function as acidic water is greatly reduced.

For example, when an anion such as chlorine is contained in the electrolytic solution, the electrolytic reaction of the electrolytic solution is as follows: 2H ₂ O → O ₂ + 4H ⁺ + 4e: 2Cl ⁻ → Cl ₂ + 2e: _{Cl 2 + H 2 O → HClO} + H + + C
l ^-: a and acidic water is produced by oxidation due to the hypochlorous acid generated by the reaction, a low pH to generate hydrogen ions further by the water electrolysis side reactions. If there is no anions such as chlorine _{ions, 3H 2 O → O 3 +} 6H + +
It is said that acidic water is generated by the oxidizing property of ozone generated by the reaction 6e. However, it is known that ozone is unstable and generates active OH and O radicals by reaction with water, and these easily react with hydrogen and decompose. The decomposition by hydrogen can be avoided by preventing the transfer of the hydrogen.

There are several methods for this. For example, first, pressure is applied from the anode side to provide a pressure difference between the cathode and the cathode to prevent the transfer of hydrogen. Second, the thickness of the ion exchange membrane is increased or a plurality of thin ion exchange membranes are joined. This is a method for increasing the resistance to hydrogen transfer by using the ion exchange membrane as a single thick ion exchange membrane. Although the second method is effective and this method is practically employed, the first method also substantially joins a plurality of thin ion exchange membranes in order to impart pressure resistance to the ion exchange membrane. A thick ion exchange membrane or a thick ion exchange membrane formed from the beginning is used. Although the use of this thick ion exchange membrane increases the resistance to the transfer of hydrogen, on the contrary, there arises a problem in the sealing property between the ion exchange membrane and the electrode chamber frame which holds and fixes the ion exchange membrane. In other words, although the ion exchange membrane itself is a polymer compound, it is relatively hard and therefore cannot be expected to have a sealing property by itself. There is a problem that a liquid leak occurs only with the seal. In particular, when the ion exchange membrane is thicker, this tendency becomes stronger, and when a fluorine resin having no corrosion and corrosion elution is used as the sealing material, the fluorine resin has almost no elasticity. Since the liquid sealing is performed by the ion exchange membrane, the sealing is naturally insufficient, and the generated hydrogen and the electrolyte are more likely to leak.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water electrolysis tank which has solved the above-mentioned problems of the prior art, that is, can reliably seal even if a thick ion exchange membrane is used and can maintain a high oxidation-reduction potential of acidic water. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION The present invention provides an anode compartment frame having a concave anode compartment for accommodating an anode on the inner surface thereof.
A cathode chamber frame having a concave cathode chamber for accommodating a cathode on its inner surface, and a peripheral wall having a thickness of 100 μm or more and having an outer diameter smaller than that of both frames and larger than that of the anode chamber and the cathode chamber. In a water electrolysis tank comprising a cation exchange membrane sandwiched between the two frames, a first sealing material is arranged between a peripheral portion of the cation exchange membrane and the anode chamber frame or the cathode chamber frame, and A water electrolysis tank, wherein a second seal member is disposed between the anode chamber frame and the cathode chamber frame outside the ion exchange membrane, and the first seal contacting the electrolytic solution has a high corrosion resistance, for example, a fluorine resin. It is desirable that the second seal not in contact with the electrolyte be a rubber seal having excellent sealing properties.

Hereinafter, the present invention will be described in detail. A feature of the present invention is that a double seal is used to reliably seal the ion exchange membrane of a water electrolysis tank equipped with a thick ion exchange membrane of 100 μm or more. When an ion exchange membrane composed of a plurality of ion exchange membranes or a single thick ion exchange membrane is used as a diaphragm of a water electrolyzer, sufficient sealing properties can be obtained with a normal O-ring even if the O-ring is completely crushed. I can't. Particularly, in order to prevent deterioration by contact with acidic water and alkaline water generated by water electrolysis, the O-
This tendency is even more pronounced because the ring is usually molded from fluororesin or fluororesin-coated rubber with little elasticity.
It is difficult to achieve both chemical corrosion resistance and mechanical strength (elastic strength). Therefore, in the present invention, the seal is doubled in order to achieve both the chemical corrosion resistance and the mechanical strength, and one of the two seals has the chemical corrosion resistance and the other has the mechanical strength. It is intended to be able to balance strength.

[0010] Of the double seals, the inner seal seals between the ion exchange membrane and the anode chamber frame or the cathode chamber frame and fixes the ion exchange membrane. A first donut-shaped groove is formed on the contact surface of the frame with the ion exchange membrane, and the groove is filled with a first sealant such as an O-ring. Since the first sealing material is likely to come into contact with the electrolyte solution in the electrode chamber, for example, acidic water having a strong oxidizing property, a material having corrosion resistance even if the sealing property is sacrificed to some extent using the above-described fluororesin or the like. (For example, a fluororesin wrap ring, Kalrez of DuPont). Next, the second sealing material seals between the anode chamber frame and the cathode chamber frame outside the ion exchange membrane, and since the sealing material does not come into contact with the electrolytic solution, there is almost no need to consider corrosion resistance.
In consideration of only the sealing property, it can be molded from a material having excellent sealing property, for example, rubber. However, a fluororesin rubber such as Viton (trade name) manufactured by DuPont having excellent corrosion resistance and sealing property can also be used. The sealing material is formed with a second groove on the anode chamber frame or cathode chamber frame surface outside the first groove, and is filled therein. This second sealing material has a thick ion exchange membrane inside thereof,
If the thickness is the same as that of the first sealing material, the compression may be insufficient by the thickness of the ion exchange membrane and a problem may occur in the sealing performance. With such a thickness, when optimal tightening is performed on the first seal member, the tightening is almost nearly optimal with respect to the second seal member, which is convenient.

The anode used in the water electrolysis tank of the present invention is made of a metal such as a noble metal, titanium, tantalum or the like which is stable against oxidation, or a non-metallic conductive ceramic such as carbon or silicon carbide. Substances that are resistant to elution during the production of acidic water, that is, noble metals and noble metal oxides,
Specifically, platinum, ruthenium, iridium, rhodium,
Palladium, osmium, etc., and other conductive ceramics or diamonds are used, and the base material is coated on the base material to manufacture. The thickness of the anode material is not particularly limited,
1-50 μm is preferred. Also, the cathode uses a noble metal stable against reduction, a metal such as titanium, zirconium, tantalum, or a conductive ceramic such as carbon or silicon carbide as a base material in order to maintain the purity of the generated alkaline water.
Noble metals such as platinum, ruthenium, and iridium, conductive ceramics, diamond, and the like are coated on the base material as a cathode material to manufacture. The thickness of the cathode material is preferably 1 to 50 μm. Although the shape of these electrodes is not particularly limited, it is desirable to form them into a plate having an aperture ratio of 40 to 80% in order to smoothly progress the reaction. The anode chamber frame and the cathode chamber frame are preferably made of a material having a stable film such as quartz or PTFE resin formed on the surface.

FIG. 1 is an exploded longitudinal sectional view showing an example of the water electrolysis tank of the present invention. The electrolytic cell body 1 has an anode chamber frame 4 in which a concave portion 2 is formed on the inner surface and a porous anode 3 is accommodated in the concave portion, and a concave cathode 5 is formed in the inner surface and a porous cathode 6 is accommodated in the concave portion. A cathode chamber frame 7;
Between the anode 3 and the cathode 4
Is fixed so that the ion-exchange membrane 8 spread from the peripheral portion is sandwiched by both poles. A first groove 9 is formed in a donut shape at a position corresponding to a peripheral portion of the ion exchange membrane 8 of the cathode chamber frame 7, and a first sealing material 10 made of fluororesin is formed in the first groove 9. Is further accommodated, and a second concave groove 11 is formed in a donut shape at a position further outside the cathode chamber frame 7 in direct contact with the anode chamber frame 4. Of the second sealing material 12 are accommodated,
The sealing members 10 and 12 are deformed by pressing the anode chamber frame and the cathode chamber frame inward, and are elastically filled in the grooves 9 and 11. First sealing material 9
Is sealed between the cathode chamber frame 7 and the ion exchange membrane 8 to prevent leakage of the catholyte solution. Even if leakage occurs through the first seal material 9, the second seal existing outside is also provided. Lumber 12
Thus, liquid leakage outside the electrolytic cell is reliably prevented.

[0013]

EXAMPLE Next, an example of a liquid leakage test using a water electrolysis tank according to the present invention will be described, but the example does not limit the present invention.

[0014]

Example 1 A liquid leakage test was performed using the electrolytic cell shown in FIG. A porous anode made of titanium supporting an iridium oxide catalyst is supported on the anode side of a cation exchange membrane Nafion 117 (manufactured by DuPont) having a thickness of 120 μm and an outer diameter of 18 cm, and a platinum catalyst is supported on the cathode side. Each of the titanium porous cathodes was brought into close contact with each other. The outer diameter of both the anode compartment frame and the cathode compartment frame is 30 cm, and 6.5 mm from the periphery of the cathode compartment frame surface.
A donut-shaped first groove having a width of 5 mm and a depth of 3 mm is provided at a position of 5 cm, and a donut-shaped 5 mm width and a depth of 3 mm at a position 5 cm from the periphery.
Second concave grooves each having a thickness of mm were formed. A corrosion-resistant fluororesin wrap ring was fitted into the first inner groove, and a Viton ring was fitted into the second outer groove. The tank was filled with pure water and kept for 24 hours while applying a pressure of 0.3 MPa, but no liquid leakage was observed.

[0015]

Comparative Example 1 Except that the thickness of the cation exchange membrane was 50 μm, only the first concave groove of Example 1 was formed in the cathode chamber frame, and a fluororesin wrap ring was fitted into this concave groove. An electrolytic cell was constructed under the same conditions as in Example 1, filled with pure water, and kept for 24 hours while applying a pressure of 0.3 MPa.
No liquid leakage was observed.

[0016]

[Comparative Example 2] Two or three cation exchange membranes each having a thickness of 50 µm were superposed on each other, and the apparent thickness was 100 µm or 150 µm.
A liquid leakage experiment was performed under the same conditions as in Comparative Example 1 except that the cation exchange membrane was m. In the case of two sheets, only slight bleeding of the liquid was observed. In the case of stacking, the liquid leakage advanced to such an extent that dripping could be visually observed. As a result, it was found that a single seal was insufficient when the thickness of the ion exchange membrane exceeded 100 μm, and that a double seal was required as in the above embodiment.

[0017]

The present invention provides an anode chamber frame having a concave anode chamber for accommodating an anode on the inner surface thereof, a cathode chamber frame having a concave cathode chamber for accommodating a cathode on the inner surface thereof, and a thickness of 100 μm or more. Wherein the outer diameter of the water electrolysis tank is smaller than the two frames and larger than the anode chamber and the cathode chamber, and includes a cation exchange membrane whose periphery is sandwiched between the two frames. A first space between the peripheral portion of the exchange membrane and the anode chamber frame or the cathode chamber frame;
A water electrolysis tank, wherein a sealing material is arranged and a second sealing material is arranged between the anode chamber frame and the cathode chamber frame outside the cation exchange membrane.

In the present invention, the first (inner) seal between the ion exchange membrane and the frame surfaces of the two electrolysis chambers and the second (outer) seal between the two electrolysis chamber frame surfaces are double-sealed. Even if the electrolytic solution permeates through the first seal and leaks outward, the second seal is present, so that the liquid does not further leak outward. Further, in the present invention, it is preferable that the first seal is an O-ring made of fluororesin, and the second seal is an O-ring made of rubber. Therefore, the corrosion resistance is improved even at the expense of the sealability. Regarding the electrolyte passing through the first seal, it is not necessary to consider the corrosion resistance, and the second seal material, which can select the material by focusing only on the sealability, is surely provided. It is possible to provide a seal structure having both corrosion resistance and sealability by preventing liquid leakage.

[Brief description of the drawings]

FIG. 1 is an exploded longitudinal sectional view showing an example of a water electrolysis tank of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrolyzer main body 2 ... Concave part 3 ... Anode 4
... Anode chamber frame 5 ... Recess 6 ... Cathode 7 ... Cathode chamber frame 8 ... Ion exchange membrane 9 ... First concave groove 10 ...
1st sealing material 11 ・ ・ ・ 2nd groove 12 ・ ・ ・ 2nd sealing material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Shimune 2023-15 Endo, Fujisawa City, Kanagawa Prefecture Inside Permelec Electrode Co., Ltd. (72) Inventor Masashi Tanaka 2023-15 Endo, Fujisawa City, Kanagawa Prefecture Permelec Electrode Co., Ltd. (72) Inventor Yoshinori Nishiki 2023-15 Endo, Fujisawa City, Kanagawa Prefecture Inside Permelec Electrode Co., Ltd. (72) Inventor Naoya Hayami 33 Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Production Technology Research Institute, Inc.

Claims (2)

[Claims] 1. An anode chamber frame having a concave anode chamber accommodating an anode on its inner surface, a cathode chamber frame having a concave cathode chamber accommodating a cathode on its inner surface, and a thickness of 100 μm.
m or more, and the outer diameter thereof is smaller than the two frames, the diameter is larger than the anode chamber and the cathode chamber, and the periphery thereof has a cation exchange membrane sandwiched between the two frames. A first sealing material is disposed between the peripheral portion of the cation exchange membrane and the anode chamber frame or the cathode chamber frame, and a second sealing material is provided between the anode chamber frame and the cathode chamber frame outside the cation exchange membrane. A water electrolysis tank characterized by being arranged. 2. The method according to claim 1, wherein the first sealing material is made of O-
The water electrolysis tank according to claim 1, wherein the second sealing member is a rubber O-ring.