ELECTROLYTIC DEVICE AND ELECTRODE

Abstract

According to one embodiment, an electrolytic device includes an electrolytic cell including a first electrode, a second electrode opposing the first electrode and a diaphragm provided between the first electrode and the second electrode. The first electrode is formed of a plate including a first surface opposing the diaphragm, a second surface located on an opposite side to the diaphragm, and first recess portions formed in the first surface with a first pattern. The first recess portions include a bottom surface apart from the first surface and through-holes opening to the second surface of the first electrode and to a part of the bottom surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of PCT Application No. PCT/JP2015/075626, filed Sep. 9, 2015 and based upon and claiming the benefit of priority from Japanese Patent Application No. 2014-191565, filed Sep. 19, 2014, the entire contents of all of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an electrolytic device and an electrode used for the electrolytic device.

BACKGROUND

As an electrolytic device, an electrolyzed-water production device for producing ionized alkaline water, ozone water, aqueous hypochlorous acid or the like is conventionally known. As the electrolyzed-water production device, a device comprising a three-chamber electrolytic tank (electrolytic cell) has been proposed. The three-chamber cell includes an electrolytic container divided into three chambers, that is, an anode chamber, an intermediate chamber and a cathode chamber by diaphragms. In such an electrolytic device, for example, salt water is introduced into the intermediate chamber, and water is introduced into the cathode chamber and the anode chamber on the right and left sides. Thus, the salt water in the intermediate chamber is electrolyzed by the anode and the cathode to produce aqueous hypochlorous acid from gaseous chlorine produced in the anode chamber and sodium hydroxide solution in the cathode chamber. Hypochlorous acid thus produced can be utilized as sterilizing solution and sodium hydroxide solution as a cleaning solution.

However, an electrolytic device having such a three-chamber cell involves reactions in a complicated way around the anode, which proceed from chlorine ions to gaseous chloride and then to hypochlorous acid. Here, if the reaction system does not take place appropriately, competitive gaseous oxygen is produced and thus the productivity of hypochlorous acid is reduced. Further, gaseous chloride and hypochlorous acid produced here are strong oxidizers, which may cause deterioration of diaphragms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically showing an electrolytic device according to a first embodiment.

FIG. 2 is an exploded perspective view showing an electrolytic cell of the electrolytic device according to the first embodiment.

FIG. 3 is a sectional view of the electrolytic cell.

FIG. 4 is an expanded perspective view showing a first electrode and an anode cover of the electrolytic cell.

FIG. 5 is a perspective view showing a first surface side of the first electrode.

FIG. 6 is a perspective view showing a second surface side of the first electrode.

FIG. 7 is a partially expanded perspective view showing the first electrode.

FIG. 8 is a plan view of the first electrode as viewed from the first surface side.

FIG. 9 is a sectional view of the first electrode and an anion-exchange membrane, taken along line A-A of FIG. 8.

FIG. 10 is a sectional view of the first electrode and the anion-exchange membrane, taken along line B-B of FIG. 8.

FIG. 11 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a first modification.

FIG. 12 is a plan view of the first electrode according to the first modification as viewed from the first surface side.

FIG. 13 is a sectional view of the first electrode and an anion-exchange membrane, taken along line C-C of FIG. 12.

FIG. 14 is a sectional view of the first electrode and an anion-exchange membrane, taken along line D-D of FIG. 12.

FIG. 15 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a second modification.

FIG. 16 is a plan view of the first electrode according to the second modification as viewed from the first surface side.

FIG. 17 is a sectional view of the first electrode and an anion-exchange membrane, taken along line E-E of FIG. 16.

FIG. 18 is a sectional view of the first electrode and an anion-exchange membrane, taken along line F-F of FIG. 16.

FIG. 19 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a third modification.

FIG. 20 is a plan view of the first electrode according to the third modification as viewed from the first surface side.

FIG. 21 is a sectional view of the first electrode and an anion-exchange membrane, taken along line G-G of FIG. 20.

FIG. 22 is a sectional view of the first electrode and an anion-exchange membrane, taken along line H-H of FIG. 20.

FIG. 23 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a fourth modification.

FIG. 24 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a fifth modification.

FIG. 25 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a sixth modification.

FIG. 26 is a partially expanded perspective view showing a first electrode of an electrolytic device according to a seventh modification.

FIG. 27 is a plan view of the first electrode according to the seventh modification as viewed from the first surface side.

FIG. 28 is a sectional view of the first electrode and an anion-exchange membrane, taken along line I-I of FIG. 27.

FIG. 29 is a partially expanded perspective view showing a first electrode of an electrolytic device according to an eighth modification.

FIG. 30 is a plan view of the first electrode according to the eighth modification as viewed from the first surface side.

FIG. 31 is a sectional view of the first electrode and an anion-exchange membrane, taken along line J-J of FIG. 30.

DETAILED DESCRIPTION

Various embodiments will be described below with reference to the accompanying drawings. In general, according to one embodiment, an electrolytic device comprises an electrolytic cell comprising a first electrode, a second electrode opposing the first electrode and at least one diaphragm provided between the first electrode and the second electrode. The first electrode is formed of a plate comprising a first surface opposing the diaphragm, a second surface located on an opposite side to the diaphragm, and first recess portions formed in the first surface with a first pattern. The first recess portions include a bottom surface apart from the first surface and through-holes each opening to the second surface of the first electrode and to a part of the bottom surface.

Throughout the embodiments, common structural members are designated by the same reference symbols, and the explanation therefor will not be repeated. Further, the drawings are schematic diagrams designed to assist the reader to understand the embodiments easily. Thus, there may be sections where the shape, dimensions, ratio, etc. are different from those of the actual devices, but they can be re-designed as needed with reference to the following explanations and publicly known techniques.

First Embodiment

FIG. 1 is a diagram briefly showing an electrolytic device according to the first embodiment. In this embodiment, the electrolytic device 10 is constituted as an electrolysis water production device. The electrolytic device 10 comprises, as shown in FIG. 1, a three-chamber electrolytic cell 11. The electrolytic cell 11 is formed into a flat rectangle box, inside of which is divided by an anion-exchange membrane 16 as a first diaphragm and a cation-exchange membrane 18 as a second diaphragm into an intermediate chamber 15a, and also an anode chamber 15b and a cathode chamber 15c located on both sides of the intermediate chamber 15a. A first electrode (anode) 14 is provided in the anode chamber 15b so as to oppose the anion-exchange membrane 16. A second electrode (cathode) 20 is provided in the cathode chamber 15c so as to oppose the cation-exchange membrane 18.

The electrolytic device 10 comprises an electrolyte supplier 19 which supplies an electrolyte, for example, saturated salt water, to the intermediate chamber 15a of the electrolytic cell 11, a water supplier 21 which supplies a solution to be electrolyzed, for example, water, to the anode chamber 15b and the cathode chamber 15c and a power supply 23 that applies positive and negative voltages respectively to the first and second electrodes 14 and 20.

The electrolyte supplier 19 comprises a salt water tank 25 to produce saturated salt water, a supply pipe 19a which conveys saturated salt water from the salt water tank 25 to a lower portion of the intermediate chamber 15a, a liquid feed pump 29 provided in the supply pipe 19a and a drainage pipe 19b which sends the electrolyte which has flowed through the inside of the intermediate chamber 15a from an upper portion of the intermediate chamber 15a to the salt water tank 25.

The water supplier 21 comprises a water supply source (not shown) which supplies water, a water supply pipe 21a which guides water to lower portions of the anode chamber 15b and the cathode chamber 15c from the water supply source, a first drainage pipe 21b to discharge the water which has flowed through the anode chamber 15b from an upper portion of the anode chamber 15b, a second drainage pipe 21c to discharge the water which has flowed through the cathode chamber 15c from an upper portion of the cathode chamber 15c and a gas-liquid separator 27 provided in the second drainage pipe 21c.

The operation of the electrolytic device 10 configured as described above, which actually electrolyzes salt water to produce an acidic solution (aqueous hypochlorous acid and hydrochloric acid) and alkaline water (sodium hydroxide) will now be described.

As shown in FIG. 1, the liquid feed pump 29 is operated to supply saturated salt water to the intermediate chamber 15a of the electrolytic cell 11, and water to the anode chamber 15b and the cathode chamber 15c. At the same time, a positive voltage and a negative voltage are applied to the first electrode 14 and the second electrode 20, respectively, from the power supply 23. Sodium ions electrolytically dissociated in the salt water which has flowed into the intermediate chamber 15a are attracted towards the second electrode 20, pass through the cation-exchange membrane 18 and flow into the cathode chamber 15c. Then, in the cathode chamber 15c, water is electrolyzed by the second electrode 20 and gaseous hydrogen and an aqueous solution of sodium hydroxide are obtained. The aqueous solution of sodium hydroxide and gaseous hydrogen thus produced flow out of the cathode chamber 15c into the second drainage pipe 21c, and are then separated into an aqueous solution of sodium hydroxide and gaseous hydrogen by the gas-liquid separator 27. The aqueous solution of sodium hydroxide (alkaline water) is discharged through the second drainage pipe 21c.

Meanwhile, chlorine ions electrolytically dissociated in the salt water in the intermediate chamber 15a are attracted towards the first electrode 14, pass through the anion-exchange membrane 16 and flow into the anode chamber 15b. Then, the chlorine ions give electrons to the anode with the first electrode 14 to produce gaseous chlorine. After that, the gaseous chlorine reacts with water in the anode chamber 15b to produce hypochlorous acid and hydrochloric acid. The acidic solution thus produced (aqueous hypochlorous acid and hydrochloric acid) is discharged from the anode chamber 15b through the first liquid drainage pipe 21b.

Next, the structure of the electrolytic cell 11 will now be described in more detail. FIG. 2 is an exploded perspective view of the electrolytic cell, and FIG. 3 is a sectional view thereof. As shown in FIGS. 2 and 3, the electrolytic cell 11 comprises an intermediate frame 22 of a rectangular frame shape, which functions as a diaphragm, an anode cover (first cover member) 24 of a rectangular plate shape having outer dimensions substantially equal to those of the intermediate frame 22, which covers one side surface of the intermediate frame, and a cathode cover (second cover member) 26 of a rectangular plate shape having outer dimensions substantially equal to those of the intermediate frame 22, which covers the other side surface of the intermediate frame.

The anion-exchange membrane 16 is disposed between the intermediate frame 22 and the anode cover 24, as a first diaphragm to separate the intermediate chamber 15a and the anode chamber 15b from each other, and the first electrode (anode plate) 14 is disposed near the anion-exchange membrane 16 in the anode chamber 15b. The cation exchange membrane 18 is disposed between the intermediate frame 22 and the cathode cover 26, as a second diaphragm to separate the intermediate chamber 15a and the cathode chamber 15c from each other, and the second electrode (cathode) 20 is disposed near the cation-exchange membrane 18 in the cathode chamber 15c.

A first inlet 34 communicating with the intermediate chamber 15a is formed in a lower end of the intermediate frame 22 and a first outlet 36 communicating with the intermediate chamber 15a is provided in an upper end thereof. The supply pipe 19a and the drainage pipe 19b are connected to the first inlet 34 and the first outlet 36, respectively.

As shown in FIGS. 2 to 4, a plurality of linear ribs 33 are provided on an inner surface of the anode cover 24, to extend in, for example, the vertical direction (the second direction Y). The ribs 33 are arranged parallel to each other while keeping a predetermined gap between adjacent ones. Between each adjacent pair of the ribs 33, a circulation groove 32a is provided to extend in the vertical direction. Further, a pair of upper and lower side grooves by which ends of each circulation groove 32a communicate are formed in the inner surface of the anode cover 24. The anode chamber 15b is defined by the circulation grooves 32a, the side grooves and the anion-exchange membrane 16. In addition, the circulation grooves 32a and the side grooves form flow paths for water.

A second inlet 37 communicating with the lower end of the circulation grooves 32a is formed in a lower portion of the anode cover 24, and a second outlet 38 communicating with the upper end of the circulation grooves 32a is formed in an upper portion of the anode cover 24. The supply pipe 21a and the first drainage pipe 21b are connected to the second inlet 37 and the second outlet 38, respectively.

A plurality of ribs 35, circulation grooves 32b, and side grooves are each formed on an inner surface of the cathode cover 26 so as to extend in the perpendicular direction (the second direction Y). The circulation grooves 32b, the side grooves and the cation-exchange membrane 18 defines the cathode chamber 15c. Further, the circulation grooves 32b and the side grooves form a flow path for water to flow.

A third inlet 39 communicating with the lower end of the circulation grooves 32b is formed in a lower portion of the cathode cover 26, and a third outlet 41 communicating with the upper end of the circulation grooves 32a is formed in an upper portion thereof. The supply pipe 21a and the second drainage pipe 21c are connected to the third inlet 39 and the third outlet 41, respectively.

As shown in FIGS. 2 and 3, frame-shaped sealing materials 40 for preventing leakage are disposed respectively between structural components, that is, between the peripheral portion of the anode cover 24 and the peripheral portion of the first electrode 14; between the peripheral portions of the first electrode 14 and the anion-exchange membrane 16 and the intermediate frame 22; between the intermediate frame 22 and the peripheral portions of the second electrode 20 and the cation-exchange membrane 18; and between the peripheral portion of the second electrode 20 and the peripheral portion of the cathode cover 26.

A plurality of fixing bolts 50 are inserted through the peripheral portions of these structural components from, for example, the anode cover 24 side and the tip portions project from the cathode cover 26. A nut 52 is screwed into the tip portion of each fixing bolt 50. With the fixing bolts 50 and the nuts 52 as fastening components, the peripheral portions of the structural components are fastened respectively with each other to maintain the water tightness of the intermediate chamber 15a, the anode chamber 15b and the cathode chamber 15c.

As shown in FIGS. 2 and 3, the anion-exchange membrane 16 and the cation-exchange membrane 18 are each formed into a thin rectangular plate having an outer size substantially equal to that of the intermediate frame 22 and a thickness of about 100 to 200 μm. The anion-exchange membrane 16 and the cation-exchange membrane 18 each have characteristics of passing only specific ions. A plurality of through-holes through which the fixing bolts 50 are inserted are formed in the peripheral portions of the anion-exchange membrane 16 and the cation-exchange membrane 18.

The anion-exchange membrane 16 is disposed to oppose one surface side of the intermediate frame 22, and the peripheral portion thereof is tightly attached to the intermediate frame 22 through the sealing material 40. Similarly, the cation-exchange membrane 18 is disposed to oppose the other surface side of the intermediate frame 22 and the peripheral portion thereof is tightly attached to the intermediate frame 22 through the sealing material 40. Note that the first diaphragm and the second diaphragm may be formed from not only an ion-exchange membrane but a porous membrane having water permeability.

The first electrode 14 and the second electrode 20 are each formed from a metal plate having a thickness of about 1 mm, formed into a rectangular shape having an outer size substantially equal to that of the intermediate frame 22. The first electrode 14 and the second electrode 20 each have a central portion (effective region) where micro-through-holes for passing liquid are formed, and a peripheral portion in which a plurality of through-holes through which fixing bolts 50 are inserted are formed. The first electrode 14 includes a contact terminal 14b projecting from a side edge thereof. Similarly, the second electrode 20 includes a contact terminal 20b projecting from a side edge thereof.

The first electrode 14 is arranged to oppose to and be tightly contact with the anion-exchange membrane 16. The second electrode 20 is arranged to oppose to and be tightly contact with the cation-exchange membrane 18.

Next, the structure of the first electrode (anode) 14 will be described in detail as a typical example of the electrodes.

FIG. 4 is an expanded perspective view of the first electrode and the anode cover. FIG. 5 is a perspective view of the first surface side of the first electrode. FIG. 6 is a perspective view of the second surface side of the first electrode. FIG. 7 is a partially expanded perspective view of the first electrode. FIG. 8 is a plan view of the first electrode as viewed from the first surface side. FIG. 9 is a sectional view of the first electrode and the anion-exchange membrane, taken along line A-A of FIG. 8. FIG. 10 is a sectional view of the first electrode and the anion-exchange membrane, taken along line B-B of FIG. 8.

As shown in FIG. 4 to FIG. 7, the first electrode 14 has, for example, a porous, mesh structure in which a great number of recesses and through-holes are made in a matrix 17 of a rectangular metal plate. The matrix 17 includes a first surface 17a and a second surface 17b opposing substantially parallel to the first surface 17a. The distance between the first surface 17a and the second surface 17b, that is, the plate board thickness T, is, for example 0.8 mm. The first surface 17a opposes the first diaphragm 16 and the second surface 17b opposes the anode cover 24. The matrix 17 may be made from a metal such as titanium.

In the first surface 17a of the matrix 17, a first recess R1 having a first pattern is formed over the entire surface. In the second surface 17b of the matrix 17, a second recess R2 having a second pattern different from the first pattern is formed over the entire surface.

In this embodiment, the first recess R1 of the first pattern comprises a plurality of thin linear first recess portions 42 formed in the first surface 17a of the matrix 17 and the first recess portions 42 are each opened in the first surface 17a. Each of the first recess portions 42 includes a bottom surface (bottom portion) 42a which is apart from the first surface 17a, that is, recessed from the first surface 17a by a predetermined depth. The second recess R2 of the second pattern comprises a plurality of thick or coarse linear second recess portions 44 formed in the second surface 17b of the matrix 17 and the second recess portions 44 are each opened to the second surface 17b. The first recess portions 42 and the second recess portions 44 are formed in the entire rectangular effective region excluding the peripheral portion of the matrix 17. A plurality of first recess portions 42 communicate with one second recess 44 and each of the communicating portions forms a through-hole 46. Each of the through-holes 46 opens to a part of the bottom surface 42a of the first recess portion 42 and opens to the second surface 17b of the matrix 17. The entire surface of the first electrode 14 is covered with an iridium oxide catalyst. The iridium oxide catalyst produces a lower overvoltage in the gaseous chlorine production than in the competitive gaseous oxygen production, and if there are a certain number of chlorine ions around the anode, gaseous chlorine is selectively produced.

As shown in FIGS. 4 to 10, in this embodiment, the first recess portions 42 are each formed into straight lines extending in the first direction X, for example, a horizontal direction. The first recess portions 42 are arranged to be parallel to one another. The first recess portions 42 are each formed to be longer than an opening width W3 of the second recess portions 44, which will be described later. In this embodiment, the first recess portions 42 each extend continuously from one end to the other end of the effective region of the first surface 17a (central region of the rectangular shape, excluding the peripheral portion on the first surface). An opening width W1 of the first recess portions 42 is, for example, 0.4 mm, a pitch P1 of the first recess portions 42 in the arranging direction Y is 0.5 mm, a depth D1 of the first recesses 42 is less than a half of the thickness T of the matrix 17, more specifically, for example, 0.1 to 0.2 mm. In this embodiment, the first recess portions 42 are each formed so as to widen from the bottom portion (bottom surface 42a) side toward the first surface 17a, more specifically, to have substantially a trapezoidal shape in cross section. The both side surfaces which define each first recess 42 extend while inclining with respect to the first surface 17a. With this structure, some of the first recess portions 42 communicate with a plurality of second recess portions 44 by a through-width W2 of 0.2 mm.

In this embodiment, the second recess portions 44 on the second surface 17b side are formed in a straight line extending in a direction crossing the first direction X, that is, for example, a second direction Y orthogonal to the direction X. The second recess portions 44 are arranged to be parallel to each other. The second recess portions 44 each extend from one end to the other end of the effective region (central region of the rectangular shape, excluding the peripheral portion on the second surface) of the second surface 17b. An opening width W3 of the second recess portions 44 is sufficiently larger than the opening width W1 of the first recess portions 42, for example, 2.4 mm, a pitch P2 of the second recess portions 44 in the arranging direction X is 3 mm, and a depth D2 of the second recess portions 44 is greater than a half of the thickness T of the matrix 17, more specifically, 0.6 to 0.7 mm. In this embodiment, the second recess portions 44 are each formed so as to widen from the bottom side toward the second surface 17b, more specifically, to have substantially a trapezoidal shape in cross section. The both side surfaces which define each second recess 44 42 extend while inclining with respect to the second surface 17b. With this structure, the second recess portions 44 communicate with a plurality of first recess portions 42 by a through-width W4 of 1.2 mm.

The first electrode 14 configured as above can be produced by the following procedure, for example. That is, the first surface 17a and the second surface 17b of the matrix 17 are etched to be partially cut out, thus forming the first recess R1 of the first pattern and the second recess R2 of the second pattern. The cross-sections of the first recess portions 42 and the second recess portions 44 may be various shapes, more specifically, not only a trapezoidal but also rectangular, semicircular, elliptical, arc-like and the like. Further, the angle made by the first recess portions 42 and the second recess portions 44 crossing therewith is not limited to right-angles, but may be any other angles.

With the structure, the first recess portions 42 and the second recess portions 44 of the first electrode 14 communicate respectively with each other at intersections to form a great number of through-holes 46. The first surface 17a opposing the first diaphragm 16 includes the most, more specifically, 80% of the surface opened by the first recess portions 42, and the area opened and made to communicate is set as low as 16% of the surface area of the electrode. Further, in consideration of the collection of bubbles from the through-holes 46, the water flow is set in the width direction (the second direction Y) of the through-holes 46. As described, in this electrode, the matrix 17 is etched from both sides, namely, the first and second surfaces 17a and 17b, and therefore it is possible to change the open aperture ratio in each surface. Thus, this electrode can exhibit a function which cannot be attained with the conventional electrode having the same open aperture ratio in both surfaces, manufactured by, for example, a die cut process. It is preferable here that the open area ratio of the through-holes 46 formed by the first recess portions 42 and the second recess portions 44 communicating with each other with respect to the entire area of the first surface 17a be no more than a half of the open area ratio of the first recess portions 42 to the entire area of the first surface.

Note that in this embodiment, the second electrode (cathode) 20 is similar in structure to the first electrode 14.

As shown in FIGS. 3 and 4, the first electrode 14 is disposed in a direction where the extending direction Y of the second recess portions 44 and the extending direction of the circulation grooves (flow paths) 32a of the anode cover 24 substantially coincide with each other. The second surface 17b of the first electrode 14 opposes the inner surface of the anode cover 24 and is in contact with the tip end surfaces of the ribs 33. With this structure, water supplied to the anode chamber 15b flows along the circulation grooves 32a and the second recess portions 44 of the first electrode 14, that is, in a direction crossing the first recess portions 42 of the first electrode 14.

Further, as shown in FIGS. 3, 9 and 10, the first surface 17a of the first electrode 14 opposes and is tightly attached to the first diaphragm 16. Here, since the first recess portions 42 are formed in about 80% of the effective region of the first surface 17a, the bottom surfaces 42a of the first recess portions 42 are apart from the first diaphragm 16 and the first surface of the first electrode 14 by a depth of the first recess portion 42, which is 0.1 to 0.2 mm. As shown in FIG. 10, the main reaction occurs at the bottom surfaces (bottom portions) 42a of the first recess portions 42, slightly apart from the first diaphragm 16, and hypochlorous acid, which is a produce, is collected from the tiny gaps made by the first recess portions 42 through the through-holes 46 into the anode chamber 15b. Thus, it is possible to achieve high production efficiency and prevention of degradation of the diaphragm both at the same time.

According to the electrolytic device 10 of the first embodiment, which employs the first electrode 14 having the above-described structure, an outstanding advantageous effect can be obtained as compared to the case of employing a conventional electrode formed by stamping (punching process) or expanding after making nicks (expand/lath processing). In other words, a great number of first recess portions 42 are formed in the first surface 17a which opposes the first diaphragm 16 of the first electrode 14 and therefore the first electrode 14 and the first diaphragm 16 can be set apart from each other by a slight distance without providing a separate member such as a spacer. With this structure, it is possible to improve the high production efficiency and the anti-degradation of the diaphragm both at the same time.

With the conventional stamping process, an electrode is basically formed to include only through-holes made from the first to second surfaces 17a and 17b with the same open area. Therefore, if the first electrode 14 and the first diaphragm 16 are attached tightly to each other, the main reaction occurs on the first surface 17a which opposes the first diaphragm 16. Here, the first surface is tightly attached to the first diaphragm, a problem may arise, in which the diaphragm 16 is degraded by reaction products. Further, when the first surface and the first diaphragm are tightly attached, another problem may arise, in which products produced by the electrolytic reaction cannot be collected, thus degrading the efficiency.

In this embodiment, the first recess portions 42 (first recess R1) are formed in the first surface 17a, which is the main reaction field, at an area ratio of high as 80%. With this structure, reaction products are quickly collected through a slight gap D1 (first recess portion 42) and through-holes 46 into the circulation grooves 32a, thereby making it possible to suppress degradation of the first diaphragm 16.

It is ideal that the first recess portions 42 have an open area occupying ratio as high as possible, but in practice, the above-described effect can be sufficiently exhibited if they occupy 60% or more of the effective region of the first surface 17a. Further, it is more effective if the pitch P1 of arrangement of the first recess portions 42 is finer to collect the products from the portions thereof which are in contact with the first diaphragm 16. In practice, the effect can be sufficiently exhibited if the pitch P1 is 0.8 mm or less. It is ideal that the depth D1 of the first recess portions 42 is less as possible, but in practice, the above-described effect can be sufficiently exhibited if it is 0.5 mm or less. Further, if the minimum width of the region in the first surface 17a of the first electrode 14 is formed, is set to 0.3 mm or less, that is, the value obtained by subtracting the opening width W1 of the first recess portions 42 from the arrangement pitch P1 of the first recesses 42 is 0.3 mm or less, it becomes easy to collect the substances produced by the electrolytic reaction from the first surface 17a tightly attached to the diaphragm. Thus, the above-described effect can be exhibited.

One of the functions of the second recess portions 44 of the first electrode 14 is to form the through-holes 46 for collecting the products from the first recess portions 42 formed shallow at high precision to the anode chamber 15b side. Another function of the second recess portions 44 is to collect the current electrolyzed by the first recess portions 42 at lower resistance. To achieve this, the second recess portions 44 are formed to be coarse linear dent portions which cross the first recess portions 42. By crossing the first recess portions 42 and the second recess portions 44 perpendicularly with each other, the intersections of the first recess portions 42 and the respective second recess portions 44 communicate with each other to extract hypochlorous acid or the like, produced in the first recess portions 42 from the through-holes 46 to the anode chamber 15b side. Note that the area ratio of the through-holes 46 with respect to the area of the first electrode 14 is set as low as 16%. This is because the region of the first recess portions 42, lost by the through-holes 46 should be made as small as possible. As the area of the through-holes 46 becomes larger, the number of chlorine ions lost by diffusion through the through-holes 46 increases. For this reason, the area of the through-holes 46 should desirably be set within 30% of the area of the electrode.

Further, in this embodiment, the first recess portions 42 and the second recess portions 44 are formed into a linear shape, whose longitudinal directions cross each other orthogonally. With this structure, one first recess portion 42 communicate with a plurality of second recess portions 44 to form a through-hole 46, thereby improving the drainage of the first recess portions 42 better than the case where the first recess portions 42 and the second recess portions 44 communicate with each other one to one. That is, a plurality of through-holes 46 are provided in one second recess 44 without making a dead end, thus forming such a structure for reaction products, especially, air bubbles to easily pass through. The linear second recess portions 44 are arranged to intersect perpendicularly with the first recess portions 42 at a coarse pitch so as to set the ratio of the area of the through-holes to as low as 16% while keeping the ratio of the open area of the first recesses 42 as high as 80%. Thus, the lowering of the concentration, which is caused by the diffusion of the electrolyte from the through-holes 46, can be prevented without the first diaphragm 16 being degraded by the reaction products.

The second recess portions 44 are arranged at a coarse pitch P2 of several millimeters, for example, 3 mm, so that the volume of the matrix 17 remains at large and the current produced by electrolysis can be supplied at lower resistance. Further, the intensity of the electrode itself can be maintained. In practice, the pitch P2 is set to 1 mm or more to obtain a sufficient feed resistance.

As described above, according to the first embodiment, it is possible to provide a long-life and efficient electrolytic device and an electrode, in which degradation of the diaphragm can be suppressed.

Next, the electrodes of electrolytic devices according to various modifications will be described.

Note that in the modifications described below, the elements which are identical to those of the first embodiment are denoted by the same reference symbols, and parts different from those of the first embodiment will be mainly described in detail.

(First Modification)

FIG. 11 is a partially expanded perspective view of the first electrode according to the first modification. FIG. 12 is a plan view of the first electrode as viewed from the first surface side. FIG. 13 is a sectional view of the first electrode and the anion-exchange membrane, taken along line C-C of FIG. 12. FIG. 14 is a sectional view of the first electrode and the anion-exchange membrane, taken along line D-D of FIG. 12.

As shown in FIG. 11 or FIG. 14, according to the first modification, the basic specification of the first electrode 14 is the same as that of the first embodiment shown in FIGS. 4 to 10 except that the second recess portions 44 of the second recess portions R2 are formed thin to have an arrangement pitch P2 of 3 mm, as in the first embodiment, but an opening width W3 of 1.6 mm and a through-width W4 of 0.4 mm.

With the above-described structure, the area ratio of the through-holes 46 is decreased to low as about 5%, thereby making it possible to further suppress the chlorine ions having passed through the first diaphragm 16 to diffuse in the circulation grooves 32a. Thus, the chlorine ion concentration in the first surface 17a of the first electrode 14 is increased to suppress the production of gaseous oxygen, thereby improving the production efficiency of acidic solution.

(Second Modification)

FIG. 15 is a partially expanded perspective view of the first electrode according to the second modification. FIG. 16 is a plan view of the first electrode as viewed from the first surface side. FIG. 17 is a sectional view of the first electrode and the anion-exchange membrane, taken along line E-E of FIG. 16. FIG. 18 is a sectional view of the first electrode and the anion-exchange membrane, taken along line F-F of FIG. 16.

As shown in FIGS. 15 to 18, according to the second modification, a plurality of second recess portions 44 which constitute the second recess R2 formed in the second surface 17b of the first electrode 14 each extend in the second direction Y which intersects the first direction X perpendicularly, but are divided into a plurality of sections without being continuous in the second direction. In other words, the second recess portions 44 of each row contain a plurality of segments of second recess portions 44 arranged in the second direction Y at a predetermined gap. The length of each segment of the second recess portions 44 in the second direction Y is equal to or greater than a total of widths of two or more of the first recess portions 42. Further, the length of the first recess portions 42 is greater than the width W3 of the second recess portions 44. With this configuration, the intersections of the first recess portions 42 and the second recess portions 44 communicate with each other to form a plurality of through-holes 46. A plurality of first recess portions 42 communicate with one segment of the second recess portions 44.

According to the second modification having the above-described structure, the second recess portions 44 of each row is divided into a plurality of segments so that wide linear portions remain between adjacent pairs of the segments of each second recess. With this structure, the mechanical strength is improved in all plane directions of the first electrode 14, and also the anisotropy of the feed resistance of the first electrode can be relaxed.

Note that in the first embodiment described above, the second recess portions 44 are formed concurrently with the circulation grooves 32a, but the first electrode 14 may be placed in the direction in which the second recess portions 44 intersect perpendicularly with the circulation grooves 32a.

(Third Modification)

FIG. 19 is a partially expanded perspective view of the first electrode according to the third modification. FIG. 20 is a plan view of the first electrode as viewed from the first surface side. FIG. 21 is a sectional view of the first electrode and the anion-exchange membrane, taken along line G-G of FIG. 20. FIG. 22 is a sectional view of the first electrode and the anion-exchange membrane, taken along line H-H of FIG. 20.

According to the third modification, the first electrode 14 comprises a large number of first recess portions 42 formed in the first surface 17a, which constitute the first recess R1. The second recesses formed in the second surface 17b of the first electrode 14 are formed from the through-holes 47. That is, the through-holes 47 are opened in the first surface 17a and the second surface 17b of the matrix 17. The through-holes 47 each have, for example, a circular shape whose diameter is larger than the width W1 of the first recess portions 42. In other words, the opening length of the through-holes 47 in the second direction Y is grater than the width W1 of the first recess portions 42. A plurality of first recess portions 42 communicate with one through-hole 47.

Since high precision is required, the first recess portions 42 of the first electrode 14 are formed by etching or photolithography, but the through-holes 47 as the second recesses are not so highly precise and may be formed by the conventional punch process.

(Fourth Modification)

FIG. 23 is a partially expanded perspective view of the first electrode according to the fourth modification. According to the fourth modification, a plurality of first recess portions 42 which constitute the first recess R1 formed in the first surface 17a of the first electrode 14 each extend in the first direction X, but are divided into a plurality of sections without being continuous in this direction. In other words, the first recess portions 42 of each row contain a plurality of segments of first recess portions 42 arranged in the first direction X at a predetermined gap. The length of each segment of the first recess portions 42 is greater than the width W3 of the second recess portions 44. With this configuration, the intersections of the first recess portions 42 and the second recess portions 44 communicate with each other to form a plurality of through-holes 46. A plurality of segments of first recess portions 42 communicate with a respective second recess portion 44.

According to the fourth modification having the above-described structure, the first recess portions 42 of each row is divided into a plurality of segments so that linear portions remain between adjacent pairs of the segments of each first recess. With this structure, the mechanical strength is improved in all plane directions of the first electrode 14, and also the anisotropy of the feed resistance of the first electrode can be relaxed.

(Fifth Modification)

FIG. 24 is a partially expanded perspective view of the first electrode according to the fifth modification. The shape of the first recess portions 42 formed in the first surface 17a of the first electrode 14 is not limited to linear, but may be in some other shape. According to the fifth modification, the first recess portions 42 formed in the first surface 17a of the first electrode 14 are not linear, but extend along the direction X while being bent at two or more locations.

(Sixth Modification)

FIG. 25 is a partially expanded perspective view of the first electrode according to the fifth modification. According to the fifth modification, the first recess portions 42 which formed in the first surface 17a of the first electrode 14 and constitute the first recess R1 extending along the first direction X to be curved or waved at two or more locations.

(Seventh Modification)

FIG. 26 is a partially expanded perspective view showing the first electrode according to the seventh modification. FIG. 27 is a plan view of the first electrode as viewed from the first surface side. FIG. 28 is a sectional view of the first electrode and the anion-exchange membrane, taken along line I-I of FIG. 27.

As shown in FIGS. 26 to 28, according to the seventh modification, the first recess R1 formed in the first surface 17a of the first electrode 14 include a plurality of third recess portions 45 in addition to the first recess portions 42. The third recess portions 45 are formed by forming a notch in at least one part of a wall portion which separates adjacent pairs of first recesses 42 from each other. The third recess portions 45 are each opened in regions other than the through-holes 46 in the first surface 17a, so as to make adjacent pairs of first recess portions 42 communicate with each other. In this modification, the third recess portions 45 each extend over the most of the region between two through-holes 46 adjacent in the first direction X.

According to the seventh modification having the above-described structure, the area on the first surface 17a which is brought into in contact with the diaphragm can be further reduced by providing the third recess portions. Further, the main reaction region of the electrode is the lower surfaces of the first recesses R1 and the area of the reaction region can be expanded by the third recess portions.

(Eighth Modification)

FIG. 29 is a partially expanded perspective view showing the first electrode according to the eighth modification. FIG. 30 is a plan view of the first electrode as viewed from the first surface side.

FIG. 31 is a sectional view of the first electrode and the anion-exchange membrane, taken along line J-J of FIG. 30.

As shown in FIGS. 29 and 30, according to the eighth modification, the basic structure of the first electrode 14 is the same as that of the seventh modification described above except that the third recess portions 45 are intermittently formed at two or more locations in the first direction X in the region between two through-holes 46 adjacent in the first direction X. That is, the third recess portions 45 are formed so that the wall portion which separates the adjacent first recess portions 42 from each other remain partially. In this modification, for example, four of the third recess portions 45 are formed in the region between two through-holes 46 adjacent in the first direction X. Further, the third recess portions 45 are formed in one row along the second direction Y.

In the eighth modification having the above-described structure, the third recess portions are provided intermittently, i.e., the length or width of each third recess portion is reduced, and thus the amount of deformation of the diaphragm which may warp along the first recesses R1 can be reduced. Therefore, it is possible to set the positions of the diaphragm and the electrode more precisely.

Moreover, according to the eighth modification, as shown in FIG. 31, the first electrode 14 comprises a catalytic layer 54 formed on the first recess R1 except for the first surface 17a. In other words, the catalyst is formed on the entire first electrode 14 but the first surface 17a, which is a region brought into contact with the diaphragm. With this structure, the electrolytic reaction is prohibited on the first surface in contact with the diaphragm, thereby making it possible to prolong the life of the diaphragm.

Note that the eighth modification is described for the case where the third recess portions are arranged in line along the second direction Y, but the arrangement is not limited to this. The third recess portions may as well be arranged to be shifted from each other in the first direction, or, for example, in a staggered manner.

The present invention is not limited to the embodiments and modifications described above but the constituent elements of the invention can be modified in various manners without departing from the spirit and scope of the invention. Various aspects of the invention can also be extracted from any appropriate combination of a plurality of constituent elements disclosed in the embodiments and modifications. Some constituent elements may be deleted in all of the constituent elements disclosed in the embodiments. The constituent elements described in different embodiments may be combined arbitrarily.

For example, the first electrode and the second electrode are not limited to rectangular shapes, but various other forms may be selected. Further, the material of each structural component is not limited to that employed in the embodiments or modifications discussed, but various other materials may be selected as needed. The electrode structure discussed above may be applied not only to the first electrode but also to the second electrode (cathode). The electrolytic cell of the electrode device is not limited to a three-chamber type, but it may as well be applied to a two-chamber- or single-chamber type or any electrolytic cells with electrodes in general. The electrolytes and product are not limited to salt or hypochlorous acid, but may be developed into various electrolytes and products.

Claims

1. An electrolytic device comprising:

an electrolytic cell comprising a first electrode, a second electrode opposing the first electrode and at least one diaphragm provided between the first electrode and the second electrode,

wherein the first electrode is formed of a plate comprising a first surface opposing the diaphragm, a second surface located on an opposite side to the diaphragm, and first recess portions formed in the first surface with a first pattern,

the first recess portions include a bottom surface apart from the first surface and through-holes each opening to the second surface of the first electrode and to a part of the bottom surface.

2. The electrolytic device of claim 1, wherein an area of the first recess portions opened in the first surface of the first electrode is 60% or larger than an area of the first surface.

3. The electrolytic device of claim 1, wherein an open aperture ratio of the through-holes is 30% or less of the area of the first surface of the first electrode.

4. The electrolytic device of claim 1, wherein an open area ratio of the through-holes with respect to an area of the entire first surface is a half or less, of an opening area ratio of the first recess portions with respect to the area of the entire first surface.

5. The electrolytic device of claim 1, wherein a depth of the first recess portions is less than a half of a thickness of the first electrode.

6. The electrolytic device of claim 5, wherein the depth of the first recess portions is within 0.5 mm.

7. The electrolytic device of claim 1, wherein each of the first recess portion includes a plurality of through-holes each opening to the second surface and to a part of the bottom surface of the first recess portion.

8. The electrolytic device of claim 1, wherein the first electrode comprises second recess portion formed in the second surface with a second pattern different from the first pattern, and a plurality of parts of each second recess portion communicate with a respective one of the first recess portions to form the plurality of through-holes.

9. The electrolytic device of claim 8, wherein the first recess portions extend in a first direction, respectively, and the second recess portions open to the second surface and include an opening dimension in the first direction, greater than a width of the first recess portions, and

a length of the first recess portions in the first direction is longer than a width of the second recess portions in the first direction, and a plurality of the first recess portions communicate with a respective one of the second recess portions to form the through-holes.

10. The electrolytic device of claim 9, wherein the first recess portions are arranged in a width direction thereof at a first pitch, and the second recess portions are arranged in a width direction thereof at a second pitch greater than the first pitch.

11. The electrolytic device of claim 10, wherein the first pitch of the first recess portions is 0.8 mm or less.

12. The electrolytic device of claim 10, wherein the second pitch of the second recess portions is 1 mm or greater.

13. The electrolytic device of claim 10, wherein a value obtained by subtracting the opening width W1 of the first recess portions from an arrangement pitch P1 of the first recess portions is 0.3 mm or less.

14. The electrolytic device of claim 9, wherein a depth of the second recess portions is greater than a half of the thickness of the first electrode.

15. The electrolytic device of claim 9, wherein the second recess portions extend in a second direction different from the first direction.

16. The electrolytic device of claim 15, wherein a plurality of the second recess portions communicate with a respective one of the first recess portions to form respective ones of the through-holes.

17. The electrolytic device of claim 14, wherein the first recess portions extend continuously in the first direction from one end to an other end of an effective region of the first electrode and the second recess portions extend continuously in the second direction from one end to the other end of the effective region of the first electrode.

18. The electrolytic devices of claim 17, wherein the first recess portions and the second recess portions extend linearly.

19. The electrolytic device of claim 17, wherein each of the first recess portions is divided into plurality with gaps formed in the first direction.

20. The electrolytic device of claim 18, wherein the second recess portions are each divided into plurality with gaps formed in the second direction.

21. The electrolytic device of claim 9, wherein the second recess portions are constituted by through-holes penetrating the first electrode.

22. The electrolytic device of claim 1, wherein the first recess portions include a plurality of third recess portions which make each adjacent pair of the first recess portions to communicate with each other.

23. The electrolytic device of claim 1, wherein the first electrode comprises a catalytic layer formed on the first recess portions except for the first surface.

24. An electrode for use in an electrolytic device, formed in a plate-shape, the electrode comprising:

a first surface opposing a diaphragm;

a second surface located on an opposite side to the first surface; and

first recess portions formed in the first surface with a first pattern;

wherein the first recess portions include a bottom surface apart from the first surface and through-holes each opening to the second surface and to a part of the bottom surface.

25. The electrode of claim 24, wherein an area of the first recess portions opened in the first surface is 60% or larger than an area of the first surface.

26. The electrode of claim 24, wherein an open aperture ratio of the through-holes is 30% or less of an area of the first surface.

27. The electrode of claim 24, wherein an open area ratio of the through-holes with respect to an area of the entire first surface is a half or less, of an opening area ratio of the first recess portions with respect to the area of the entire first surface.

28. The electrode of claim 24, wherein a depth of the first recess portions is less than a half of a thickness of the electrode.

29. The electrode of claim 28, wherein the depth of the first recess portions is within 0.5 mm.

30. The electrode of claim 24, further comprising second recess portions formed in the second surface with a second pattern different from the first pattern, a plurality of locations of the second recess portions communicate with the first recess portions to form the through-holes.

31. The electrode of claim 24, wherein the first recess portions open to the first surface and extend in a first direction, and the second recess portions open to the second surface and having an opening length greater than a width of the first recess portions in a second direction crossing the first direction, and

a length of the first recess portion in the first direction is greater than a width of the second recess portions in the first direction and a plurality of the first recess portions are communicated with a respective of one of the second recess portions to form the through-holes.

32. The electrode of claim 24, wherein the first recess portions include a plurality of third recess portions which make each adjacent pair of the first recess portions to communicate with each other.

33. The electrode of claim 24, further comprising a catalytic layer formed on the first recess portions except for the first surface.