JP7072413B2 - How to manufacture an electrolytic cell - Google Patents

Description

The present invention relates to a method for manufacturing an electrolytic cell.

For electrolysis of alkali metal chloride aqueous solution such as saline solution and electrolysis of water (hereinafter collectively referred to as "electrolysis"), an electrolytic tank equipped with a diaphragm, more specifically, an ion exchange film or a microporous film is used. The method used is being used. This electrolytic cell often includes a large number of electrolytic cells connected in series inside the electrolytic cell. Electrolysis is performed by interposing a diaphragm between each electrolytic cell. In the electrolytic cell, the cathode chamber having a cathode and the anode chamber having an anode are arranged back to back through a partition wall (back plate) or via pressing by pressing pressure, bolt tightening, or the like.
The anode and cathode currently used in these electrolytic cells are fixed to the anode chamber and cathode chamber of the electrolytic cell by methods such as welding and folding, and then stored and transported to the customer. On the other hand, the diaphragm itself is stored in a state of being wound around a vinyl chloride pipe or the like and transported to the customer. At the customer's site, the electrolytic cells are arranged on the frame of the electrolytic cell, and the diaphragm is sandwiched between the electrolytic cells to assemble the electrolytic cell. In this way, the electrolytic cell is manufactured and the electrolytic cell is assembled at the customer's site. As a structure applicable to such an electrolytic cell, Patent Documents 1 and 2 disclose a structure in which a diaphragm and an electrode are integrated.

JP-A-58-048686 JP-A-55-148775

When the electrolysis operation is started and continued, each part deteriorates due to various factors, the electrolysis performance deteriorates, and each part is replaced at a certain point. The septum can be easily renewed by pulling it out from between the electrolytic cells and inserting a new septum. On the other hand, since the anode and cathode are fixed to the electrolytic cell, when the electrode is renewed, the electrolytic cell is taken out from the electrolytic cell, carried out to a dedicated renewal factory, fixed by welding, etc., and the old electrode is peeled off, and then the new electrode is used. There is a problem that very complicated work such as installing, fixing by a method such as welding, transporting to an electrolytic cell, and returning to an electrolytic cell is required. Here, it is conceivable to use the structure in which the diaphragm and the electrode described in Patent Documents 1 and 2 are integrated by thermocompression bonding for the above renewal, but the structure is relatively easy at the laboratory level. Even if it can be manufactured, it is not easy to manufacture it according to an actual commercial size electrolytic cell (for example, 1.5 m in length and 3 m in width). In addition, the electrolysis performance (electrolysis voltage, current efficiency, concentration of salt in caustic soda, etc.) and durability are extremely poor, and chlorine gas and hydrogen gas are generated on the electrodes at the interface with the diaphragm, so they are completely peeled off when used for long-term electrolysis. Therefore, it cannot be used practically.
The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for manufacturing an electrolytic cell, which can improve work efficiency at the time of electrode renewal in the electrolytic cell. ..

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved by integrating the electrolytic electrode and the new diaphragm at a temperature at which the diaphragm does not melt. We have found and completed the present invention.
That is, the present invention includes the following aspects.
[1]
For manufacturing a new electrolytic cell by arranging a laminate in an existing electrolytic cell provided with an anode, a cathode facing the anode, and a diaphragm arranged between the anode and the cathode. It ’s a method,
The step (A) of obtaining the laminate by integrating the electrode for electrolysis and the new diaphragm at a temperature at which the diaphragm does not melt.
After the step (A), the step (B) of exchanging the diaphragm in the existing electrolytic cell with the laminated body,
A method for manufacturing an electrolytic cell.
[2]
The method for manufacturing an electrolytic cell according to [1], wherein the integration is performed under normal pressure.

According to the method for manufacturing an electrolytic cell according to the present invention, it is possible to improve the work efficiency when renewing the electrodes in the electrolytic cell.

It is a schematic sectional view of an electrolytic cell. It is a schematic cross-sectional view which shows the state which two electrolytic cells are connected in series. It is a schematic diagram of an electrolytic cell. It is a schematic perspective view which shows the process of assembling an electrolytic cell. It is a schematic cross-sectional view of the reverse current absorber which an electrolytic cell can have. It is a schematic cross-sectional view of the electrode for electrolysis in one Embodiment of this invention. It is sectional drawing which illustrates one Embodiment of an ion exchange membrane. It is a schematic diagram for demonstrating the aperture ratio of the reinforced core material which constitutes an ion exchange membrane. It is a schematic diagram for demonstrating the method of forming the communication hole of an ion exchange membrane.

Hereinafter, embodiments of the present invention (hereinafter, also referred to as the present embodiment) will be described in detail with reference to the drawings as necessary. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. Further, the attached drawings show an example of an embodiment, and the embodiment is not limited to this. The present invention can be appropriately modified and carried out within the scope of the gist thereof. Unless otherwise specified, the positional relationship such as up, down, left, and right in the drawing is based on the positional relationship shown in the drawing. The dimensions and proportions of the drawings are not limited to those shown.

[Manufacturing method of electrolytic cell]
In the method for manufacturing an electrolytic cell according to the present embodiment, the laminated body is arranged in an existing electrolytic cell provided with an anode, a cathode facing the anode, and a diaphragm arranged between the anode and the cathode. This is a method for manufacturing a new electrolytic cell, and is a step of obtaining the laminated body by integrating the electrode for electrolysis and the new diaphragm at a temperature at which the diaphragm does not melt (A). ), And after the step (A), there is a step (B) of exchanging the diaphragm in the existing electrolytic cell with the laminated body.
As described above, according to the method for manufacturing an electrolytic cell according to the present embodiment, the electrode for electrolysis and the diaphragm can be integrated and used without using an impractical method such as thermocompression bonding, so that when the electrode is renewed in the electrolytic cell. Work efficiency can be improved.

In the present embodiment, the existing electrolytic cell includes an anode, a cathode facing the anode, and a diaphragm arranged between the anode and the cathode as constituent members, in other words, an electrolytic cell. Is included. The existing electrolytic cell is not particularly limited as long as it includes the above-mentioned constituent members, and various known configurations can be applied.

In the present embodiment, the new electrolytic cell further includes an electrode for electrolysis or a laminate in addition to a member already functioning as an anode or a cathode in the existing electrolytic cell. That is, the "electrolyzing electrode" arranged at the time of manufacturing a new electrolytic cell functions as an anode or a cathode, and is separate from the cathode and the anode in the existing electrolytic cell. In the present embodiment, even if the electrolytic performance of the anode and / or the cathode deteriorates due to the operation of the existing electrolytic cell, the anode and / or the cathode is provided by arranging a separate electrode for electrolysis. Performance can be updated. Further, since a new ion exchange membrane constituting the laminated body is also arranged, the performance of the ion exchange membrane whose performance has deteriorated due to operation can be updated at the same time. The term "updated performance" as used herein means that the performance is equal to or higher than the initial performance of the existing electrolytic cell before it is put into operation. ..

In the present embodiment, the existing electrolytic cell is assumed to be an "electrolytic cell that has already been put into operation", and the new electrolytic cell is assumed to be an "electrolytic cell that has not yet been put into operation". That is, once the electrolytic cell manufactured as a new electrolytic cell is put into operation, it becomes an "existing electrolytic cell in the present embodiment", and an existing electrolytic cell in which an electrolytic electrode or a laminate is arranged is "the present embodiment". It will be a new electrolytic cell in.

Hereinafter, an embodiment of an electrolytic cell will be described in detail, taking as an example a case where an ion exchange membrane is used as a diaphragm and salt electrolysis is performed. In the present specification, unless otherwise specified, the "electrolytic cell in the present embodiment" includes both the "existing electrolytic cell in the present embodiment" and the "new electrolytic cell in the present embodiment". be.

[Electrolytic cell]
First, an electrolytic cell that can be used as a constituent unit of the electrolytic cell in the present embodiment will be described. FIG. 1 is a cross-sectional view of the electrolytic cell 1.
The electrolytic cell 1 was installed in the anode chamber 10, the cathode chamber 20, the partition wall 30 installed between the anode chamber 10 and the cathode chamber 20, the anode 11 installed in the anode chamber 10, and the cathode chamber 20. The cathode 21 is provided. If necessary, the substrate 18a and the reverse current absorber 18b formed on the substrate 18a may be provided, and the reverse current absorber 18 installed in the cathode chamber may be provided. The anode 11 and the cathode 21 belonging to one electrolytic cell 1 are electrically connected to each other. In other words, the electrolytic cell 1 includes the following cathode structure. The cathode structure 40 includes a cathode chamber 20, a cathode 21 installed in the cathode chamber 20, and a reverse current absorber 18 installed in the cathode chamber 20, and the reverse current absorber 18 is shown in FIG. As shown, it has a base material 18a and a reverse current absorption layer 18b formed on the base material 18a, and the cathode 21 and the reverse current absorption layer 18b are electrically connected to each other. The cathode chamber 20 further includes a current collector 23, a support 24 that supports the current collector 24, and a metal elastic body 22. The metal elastic body 22 is installed between the current collector 23 and the cathode 21. The support 24 is installed between the current collector 23 and the partition wall 30. The current collector 23 is electrically connected to the cathode 21 via the metal elastic body 22. The partition wall 30 is electrically connected to the current collector 23 via the support body 24. Therefore, the partition wall 30, the support 24, the current collector 23, the metal elastic body 22, and the cathode 21 are electrically connected. The cathode 21 and the reverse current absorption layer 18b are electrically connected. The cathode 21 and the reverse current absorption layer may be directly connected, or may be indirectly connected via a current collector, a support, a metal elastic body, a partition wall, or the like. It is preferable that the entire surface of the cathode 21 is covered with a catalyst layer for a reduction reaction. Further, in the form of electrical connection, the partition wall 30 and the support 24, the support 24 and the current collector 23, the current collector 23 and the metal elastic body 22 are directly attached, and the cathode 21 is laminated on the metal elastic body 22. It may be in the form of being. As a method of directly attaching each of these constituent members to each other, welding or the like can be mentioned. Further, the reverse current absorber 18, the cathode 21, and the current collector 23 may be collectively referred to as the cathode structure 40.

FIG. 2 is a cross-sectional view of two adjacent electrolytic cells 1 in the electrolytic cell 4. FIG. 3 shows the electrolytic cell 4. FIG. 4 shows a process of assembling the electrolytic cell 4.

As shown in FIG. 2, the electrolytic cell 1, the cation exchange membrane 2, and the electrolytic cell 1 are arranged in series in this order. The ion exchange film 2 is arranged between the anode chamber of one electrolytic cell 1 and the cathode chamber of the other electrolytic cell 1 of the two adjacent electrolytic cells in the electrolytic cell. That is, the anode chamber 10 of the electrolytic cell 1 and the cathode chamber 20 of the electrolytic cell 1 adjacent thereto are separated by the cation exchange membrane 2. As shown in FIG. 3, the electrolytic cell 4 is composed of a plurality of electrolytic cells 1 connected in series via an ion exchange membrane 2. That is, the electrolytic cell 4 is a bipolar electrolytic cell including a plurality of electrolytic cells 1 arranged in series and an ion exchange membrane 2 arranged between adjacent electrolytic cells 1. As shown in FIG. 4, the electrolytic cell 4 is assembled by arranging a plurality of electrolytic cells 1 in series via an ion exchange membrane 2 and connecting them by a press device 5.

The electrolytic cell 4 has an anode terminal 7 and a cathode terminal 6 connected to a power source. The anode 11 of the electrolytic cell 1 located at the end of the plurality of electrolytic cells 1 connected in series in the electrolytic cell 4 is electrically connected to the anode terminal 7. Of the plurality of electrolytic cells 2 connected in series in the electrolytic cell 4, the cathode 21 of the electrolytic cell located at the opposite end of the anode terminal 7 is electrically connected to the cathode terminal 6. The current during electrolysis flows from the anode terminal 7 side toward the cathode terminal 6 via the anode and the cathode of each electrolytic cell 1. An electrolytic cell having only an anode chamber (anode terminal cell) and an electrolytic cell having only a cathode chamber (cathode terminal cell) may be arranged at both ends of the connected electrolytic cell 1. In this case, the anode terminal 7 is connected to the anode terminal cell arranged at one end thereof, and the cathode terminal 6 is connected to the cathode terminal cell arranged at the other end.

When electrolyzing salt water, salt water is supplied to each anode chamber 10, and pure water or a low-concentration sodium hydroxide aqueous solution is supplied to the cathode chamber 20. Each liquid is supplied to each electrolytic cell 1 from an electrolytic solution supply pipe (omitted in the figure) via an electrolytic solution supply hose (omitted in the figure). Further, the electrolytic solution and the product obtained by electrolysis are recovered from the electrolytic solution recovery tube (omitted in the figure). In electrolysis, sodium ions in salt water move from the anode chamber 10 of one electrolytic cell 1 to the cathode chamber 20 of the adjacent electrolytic cell 1 through the ion exchange membrane 2. Therefore, the current during electrolysis flows along the direction in which the electrolytic cells 1 are connected in series. That is, the current flows from the anode chamber 10 toward the cathode chamber 20 via the cation exchange membrane 2. With the electrolysis of salt water, chlorine gas is generated on the anode 11 side, and sodium hydroxide (solute) and hydrogen gas are generated on the cathode 21 side.

(Anode chamber)
The anode chamber 10 has an anode 11 or an anode feeder 11. The feeding body referred to here means a deteriorated electrode (that is, an existing electrode), an electrode without catalyst coating, or the like. When the electrode for electrolysis in the present embodiment is inserted to the anode side, the 11 functions as an anode feeder. When the electrode for electrolysis in the present embodiment is not inserted into the anode side, 11 functions as an anode. Further, the anode chamber 10 is arranged above the anode-side electrolytic solution supply section for supplying the electrolytic solution to the anode chamber 10 and the anode-side electrolytic solution supply section, and is arranged so as to be substantially parallel to or oblique to the partition wall 30. It is preferable to have a baffle plate and an anode-side gas-liquid separation portion which is arranged above the baffle plate and separates the gas from the electrolytic solution mixed with the gas.

(anode)
When the electrode for electrolysis in the present embodiment is not inserted into the anode side, the anode 11 is provided in the frame (that is, the anode frame) of the anode chamber 10. As the anode 11, a metal electrode such as a so-called DSA (registered trademark) can be used. DSA is an electrode of a titanium base material whose surface is coated with an oxide containing ruthenium, iridium, and titanium as components.
As the shape, any of punching metal, non-woven fabric, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting a metal wire, and the like can be used.

(Anode feeder)
When the electrode for electrolysis in the present embodiment is inserted into the anode side, the anode feeding body 11 is provided in the frame of the anode chamber 10. As the anode feeder 11, a metal electrode such as a so-called DSA (registered trademark) can be used, or titanium without a catalyst coating can be used. It is also possible to use DSA having a thin catalyst coating thickness. Furthermore, a used anode can also be used.
As the shape, any of punching metal, non-woven fabric, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting a metal wire, and the like can be used.

(Anode side electrolyte supply unit)
The anode-side electrolytic solution supply unit supplies the electrolytic solution to the anode chamber 10 and is connected to the electrolytic solution supply pipe. The anode-side electrolyte supply unit is preferably arranged below the anode chamber 10. As the anode-side electrolytic solution supply unit, for example, a pipe (dispersion pipe) having an opening formed on the surface can be used. More preferably, such pipes are arranged along the surface of the anode 11 and parallel to the bottom 19 of the electrolytic cell. This pipe is connected to an electrolytic solution supply pipe (liquid supply nozzle) that supplies the electrolytic solution into the electrolytic cell 1. The electrolytic solution supplied from the liquid supply nozzle is conveyed into the electrolytic cell 1 by a pipe, and is supplied to the inside of the anode chamber 10 through an opening provided on the surface of the pipe. By arranging the pipe along the surface of the anode 11 and parallel to the bottom 19 of the electrolytic cell, the electrolytic cell can be uniformly supplied to the inside of the anode chamber 10, which is preferable.

(Anode side gas-liquid separation part)
The anode-side gas-liquid separation portion is preferably arranged above the baffle plate. During electrolysis, the gas-liquid separation section on the anode side has a function of separating the generated gas such as chlorine gas and the electrolytic solution. Unless otherwise specified, "upper" means an upward direction in the electrolytic cell 1 of FIG. 1, and "downward" means a downward direction in the electrolytic cell 1 of FIG. 1.

During electrolysis, when the generated gas generated in the electrolytic cell 1 and the electrolytic solution become a mixed phase (gas-liquid mixed phase) and are discharged to the outside of the system, vibration is generated due to the pressure fluctuation inside the electrolytic cell 1, and the physical ion exchange membrane is physically formed. May cause damage. In order to suppress this, it is preferable that the electrolytic cell 1 in the present embodiment is provided with an anode-side gas-liquid separation portion for separating gas and liquid. It is preferable that a defoaming plate for eliminating air bubbles is installed in the gas-liquid separation portion on the anode side. When the gas-liquid multiphase flow passes through the defoaming plate, the bubbles burst, so that the electrolytic solution and the gas can be separated. As a result, vibration during electrolysis can be prevented.

(Baffle board)
It is preferable that the baffle plate is arranged above the anode-side electrolyte supply unit and is arranged substantially parallel to or diagonally to the partition wall 30. The baffle plate is a partition plate that controls the flow of the electrolytic solution in the anode chamber 10. By providing the baffle plate, the electrolytic solution (salt water or the like) can be internally circulated in the anode chamber 10 to make the concentration uniform. In order to cause internal circulation, the baffle plate is preferably arranged so as to separate the space near the anode 11 and the space near the partition wall 30. From this point of view, it is preferable that the baffle plate is provided so as to face each surface of the anode 11 and the partition wall 30. In the space near the anode partitioned by the baffle plate, the concentration of the electrolytic solution (concentration of salt water) decreases as the electrolysis progresses, and a generated gas such as chlorine gas is generated. As a result, a difference in the specific gravity of gas and liquid is generated between the space near the anode 11 partitioned by the baffle plate and the space near the partition wall 30. Utilizing this, the internal circulation of the electrolytic solution in the anode chamber 10 can be promoted, and the concentration distribution of the electrolytic solution in the anode chamber 10 can be made more uniform.

Although not shown in FIG. 1, a current collector may be separately provided inside the anode chamber 10. The current collector may have the same material and configuration as the current collector in the cathode chamber, which will be described later. Further, in the anode chamber 10, the anode 11 itself can function as a current collector.

(Septum)
The partition wall 30 is arranged between the anode chamber 10 and the cathode chamber 20. The partition wall 30 is sometimes called a separator and separates the anode chamber 10 and the cathode chamber 20. As the partition wall 30, a known separator for electrolysis can be used, and examples thereof include a partition wall obtained by welding a plate made of nickel on the cathode side and titanium on the anode side.

(Cathode chamber)
In the cathode chamber 20, when the electrolytic electrode of the present embodiment is inserted into the cathode side, 21 functions as a cathode feeder, and when the electrolytic electrode of the present embodiment is not inserted into the cathode side, 21 is Functions as a cathode. When the reverse current absorber is provided, the cathode or the cathode feeding body 21 and the reverse current absorber are electrically connected to each other. Further, it is preferable that the cathode chamber 20 also has a cathode side electrolytic solution supply unit and a cathode side gas-liquid separation unit, similarly to the anode chamber 10. Of the parts constituting the cathode chamber 20, the same parts as those constituting the anode chamber 10 will be omitted.

(cathode)
When the electrode for electrolysis in the present embodiment is not inserted into the cathode side, the cathode 21 is provided in the frame (that is, the cathode frame) of the cathode chamber 20. The cathode 21 preferably has a nickel base material and a catalyst layer that coats the nickel base material. The components of the catalyst layer on the nickel substrate include Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Examples thereof include metals such as Dy, Ho, Er, Tm, Yb and Lu, and oxides or hydroxides of the metals. Examples of the method for forming the catalyst layer include plating, alloy plating, dispersion / composite plating, CVD, PVD, thermal decomposition and thermal spraying. You may combine these methods. The catalyst layer may have a plurality of layers and a plurality of elements, if necessary. Further, the cathode 21 may be subjected to a reduction treatment if necessary. As the base material of the cathode 21, nickel, nickel alloy, iron, or stainless steel plated with nickel may be used.
As the shape, any of punching metal, non-woven fabric, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting a metal wire, and the like can be used.

(Cathode feeder)
When the electrode for electrolysis in the present embodiment is inserted to the cathode side, the cathode feeding body 21 is provided in the frame of the cathode chamber 20. The cathode feeder 21 may be coated with a catalyst component. The catalyst component may be one that was originally used as a cathode and remained. The components of the catalyst layer include Ru, C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Rh, Pd, Ag. , Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er , Tm, Yb, Lu and the like, and oxides or hydroxides of the metal. Examples of the method for forming the catalyst layer include plating, alloy plating, dispersion / composite plating, CVD, PVD, thermal decomposition and thermal spraying. You may combine these methods. The catalyst layer may have a plurality of layers and a plurality of elements, if necessary. Further, nickel, nickel alloy, iron or stainless steel without catalyst coating may be plated with nickel. As the base material of the cathode feeder 21, nickel, nickel alloy, iron, or stainless steel plated with nickel may be used.
As the shape, any of punching metal, non-woven fabric, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting a metal wire, and the like can be used.

(Reverse current absorption layer)
A material having a redox potential lower than the redox potential of the element for the catalyst layer of the cathode described above can be selected as the material of the reverse current absorption layer. For example, nickel and iron can be mentioned.

(Current collector)
The cathode chamber 20 preferably includes a current collector 23. As a result, the current collecting effect is enhanced. In the present embodiment, the current collector 23 is a perforated plate, and it is preferable that the current collector 23 is arranged substantially parallel to the surface of the cathode 21.

The current collector 23 is preferably made of an electrically conductive metal such as nickel, iron, copper, silver, or titanium. The current collector 23 may be a mixture, alloy or composite oxide of these metals. The shape of the current collector 23 may be any shape as long as it functions as a current collector, and may be plate-shaped or net-shaped.

(Metal elastic body)
By installing the metal elastic body 22 between the current collector 23 and the cathode 21, each cathode 21 of the plurality of electrolytic cells 1 connected in series is pressed against the ion exchange film 2, and each anode 11 and each. The distance between the cathode 21 and the cathode 21 is shortened, and the voltage applied to the entire plurality of electrolytic cells 1 connected in series can be reduced. By lowering the voltage, the amount of power consumption can be reduced. Further, by installing the metal elastic body 22, when the laminated body including the electrode for electrolysis in the present embodiment is installed in the electrolytic cell, the pressing pressure by the metal elastic body 22 stabilizes the electrode for electrolysis. Can be kept in place.

As the metal elastic body 22, a spiral spring, a spring member such as a coil, a cushioning mat, or the like can be used. As the metal elastic body 22, an appropriately suitable one can be adopted in consideration of the stress of pressing the ion exchange membrane and the like. The metal elastic body 22 may be provided on the surface of the current collector 23 on the cathode chamber 20 side, or may be provided on the surface of the partition wall on the anode chamber 10 side. Normally, both chambers are partitioned so that the cathode chamber 20 is smaller than the anode chamber 10. Therefore, from the viewpoint of the strength of the frame, the metal elastic body 22 is placed between the current collector 23 and the cathode 21 of the cathode chamber 20. It is preferable to provide it in. Further, the metal elastic body 23 is preferably made of a metal having electrical conductivity such as nickel, iron, copper, silver and titanium.

(Support)
The cathode chamber 20 preferably includes a support 24 that electrically connects the current collector 23 and the partition wall 30. This makes it possible to efficiently pass an electric current.

The support 24 is preferably made of a metal having electrical conductivity such as nickel, iron, copper, silver and titanium. The shape of the support 24 may be any shape as long as it can support the current collector 23, and may be rod-shaped, plate-shaped, or net-shaped. The support 24 is, for example, plate-shaped. The plurality of supports 24 are arranged between the partition wall 30 and the current collector 23. The plurality of supports 24 are arranged so that their faces are parallel to each other. The support 24 is arranged substantially perpendicular to the partition wall 30 and the current collector 23.

(Anode side gasket, cathode side gasket)
The anode-side gasket is preferably arranged on the surface of the frame constituting the anode chamber 10. The cathode side gasket is preferably arranged on the surface of the frame body constituting the cathode chamber 20. The electrolytic cells are connected to each other so that the anode-side gasket provided in one electrolytic cell and the cathode-side gasket of the electrolytic cell adjacent thereto sandwich the ion exchange membrane 2 (see FIG. 2). With these gaskets, when a plurality of electrolytic cells 1 are connected in series via the ion exchange membrane 2, airtightness can be imparted to the connection points.

The gasket is a seal between the ion exchange membrane and the electrolytic cell. Specific examples of the gasket include a frame-shaped rubber sheet having an opening formed in the center. The gasket is required to have resistance to a corrosive electrolytic solution, generated gas, and the like, and to be able to be used for a long period of time. Therefore, from the viewpoint of chemical resistance and hardness, a vulcanized product of ethylene / propylene / diene rubber (EPDM rubber), a vulcanized product of ethylene / propylene rubber (EPM rubber), a cross-linked peroxide product, or the like is usually used as a gasket. If necessary, use a gasket in which the region in contact with the liquid (contacting portion) is coated with a fluororesin such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). You can also. Each of these gaskets may have an opening so as not to obstruct the flow of the electrolytic solution, and the shape thereof is not particularly limited. For example, a frame-shaped gasket is attached with an adhesive or the like along the peripheral edge of each opening of the anode chamber frame constituting the anode chamber 10 or the cathode chamber frame constituting the cathode chamber 20. Then, for example, when two electrolytic cells 1 are connected via the ion exchange membrane 2 (see FIG. 2), each electrolytic cell 1 to which the gasket is attached may be tightened via the ion exchange membrane 2. As a result, it is possible to prevent the electrolytic solution, the alkali metal hydroxide, chlorine gas, hydrogen gas and the like generated by the electrolysis from leaking to the outside of the electrolytic cell 1.

[Laminate]
The electrode for electrolysis in this embodiment is used as a laminate with a diaphragm such as an ion exchange membrane or a microporous membrane. That is, the laminate in the present embodiment includes an electrode for electrolysis and a new diaphragm. The new diaphragm is not particularly limited as long as it is different from the diaphragm in the existing electrolytic cell, and various known diaphragms can be applied. Further, the new diaphragm may be the same as the diaphragm in the existing electrolytic cell in terms of material, shape, physical properties and the like. Specific examples of the electrode for electrolysis and the diaphragm will be described in detail later.

(Step (A))
In the step (A) of the present embodiment, the electrode for electrolysis and the new diaphragm are integrated at a temperature at which the diaphragm does not melt to obtain a laminated body.
The "temperature at which the septum does not melt" can be specified as a new softening point of the septum. The temperature may vary depending on the material constituting the diaphragm, but is preferably 0 to 100 ° C, more preferably 5 to 80 ° C, and even more preferably 10 to 50 ° C.
Further, it is preferable that the above integration is performed under normal pressure.

As a specific method of the above integration, any method other than a typical method of melting the diaphragm such as thermocompression bonding can be used, and the method is not particularly limited. As a preferable example, there is a method in which a liquid is interposed between the electrode for electrolysis and the diaphragm, which will be described later, and integrated by the surface tension of the liquid.

[Step (B)]
In the step (B) of the present embodiment, after the step (A), the diaphragm in the existing electrolytic cell is replaced with the laminated body. The method of replacement is not particularly limited, but for example, first, in an existing electrolytic cell, the fixed state of the adjacent electrolytic cell and ion exchange membrane by the press is released, and a gap is formed between the electrolytic cell and the ion exchange membrane. Then, a method of removing the existing ion exchange membrane to be renewed, then inserting the laminate into the void, and connecting the members again with a press device and the like can be mentioned. By such a method, the laminate can be arranged on the surface of the anode or cathode in the existing electrolytic cell, and the performance of the ion exchange membrane, anode and / or cathode can be updated.

[Electrode electrode for electrolysis]
In the present embodiment, the electrode for electrolysis is not particularly limited as long as it can be integrated with the new diaphragm as described above, that is, it can be integrated. The electrode for electrolysis may function as a cathode in an electrolytic cell, or may function as an anode. Further, as for the material and shape of the electrode for electrolysis, an appropriate one can be appropriately selected in consideration of the steps (A) and (B) in the present embodiment and the configuration of the electrolytic cell. Hereinafter, preferred embodiments of the electrolytic electrode in the present embodiment will be described, but these are merely examples of preferred embodiments for integration with a new diaphragm, and electrolytic electrodes other than the embodiments described later may be appropriately adopted. Can be done.

The electrode for electrolysis in the present embodiment has good handleability, and has good adhesion to a diaphragm such as an ion exchange film or a microporous film, a feeder (deteriorated electrode and an electrode not coated with a catalyst), and the like. From the viewpoint of having, the applied force per unit mass / unit area is preferably 1.6 N / (mg · cm ² ) or less, more preferably less than 1.6 N / (mg · cm ² ), and further. It is preferably less than 1.5 N / (mg · cm ² ), more preferably 1.2 N / mg · cm ² or less, and even more preferably 1.20 N / mg · cm ² or less. It is even more preferably 1.1 N / mg · cm ² or less, even more preferably 1.10 N / mg · cm ² or less, and particularly preferably 1.0 N / mg · cm ² or less, 1.00 N. It is particularly preferable that it is / mg · cm ² or less.
From the viewpoint of further improving the electrolytic performance, it is preferably more than 0.005 N / (mg · cm ² ), more preferably 0.08 N / (mg · cm ² ) or more, and further preferably 0.1 N / mg. -Cm ² or more, more preferably 0.14 N / (mg · cm ² ) or more. From the viewpoint of facilitating handling in a large size (for example, size 1.5 m × 2.5 m), 0.2 N / (mg · cm ² ) or more is even more preferable.
The applied force can be set within the above range by appropriately adjusting, for example, the pore size, the thickness of the electrode, the arithmetic mean surface roughness, etc., which will be described later. More specifically, for example, when the opening ratio is increased, the applied force tends to be small, and when the opening ratio is decreased, the applied force tends to be large.
In addition, good handleability is obtained, and it has good adhesive strength with diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes, and feeders without catalyst coating, and from the viewpoint of economic efficiency. The mass per unit area is preferably 48 mg / cm ² or less, more preferably 30 mg / cm ² or less, still more preferably 20 mg / cm ² or less, and further handleability and adhesiveness. From a comprehensive viewpoint including economic efficiency, it is preferably 15 mg / cm ² or less. The lower limit is not particularly limited, but is, for example, about 1 mg / cm ² .
The mass per unit area can be set within the above range by, for example, appropriately adjusting the pore size, the thickness of the electrode, and the like, which will be described later. More specifically, for example, if the thickness is the same, increasing the opening ratio tends to reduce the mass per unit area, and decreasing the opening ratio tends to increase the mass per unit area. be.

The force can be measured by the following method (i) or (ii), and the details are as described in Examples. The applied force is a value obtained by the measurement of the method (i) (also referred to as "applied force (1)") and a value obtained by the measurement of the method (ii) (also referred to as "applied force (2)"). Although they may be the same or different, it is preferable that the value is less than 1.5 N / mg · cm ² regardless of the value.

[Method (i)]
Inorganic particles and a binder were applied to both sides of a nickel plate (thickness 1.2 mm, 200 mm square) obtained by blasting with alumina of grain number 320 and a film of a perfluorocarbon polymer having an ion exchange group introduced therein. An ion exchange membrane (170 mm square, details of the ion exchange membrane referred to here are as described in Examples) and an electrode sample (130 mm square) are laminated in this order, and this laminate is made of pure water. After sufficient immersion, the excess water adhering to the surface of the laminate is removed to obtain a measurement sample. The arithmetic average surface roughness (Ra) of the nickel plate after the blast treatment is 0.5 to 0.8 μm. The specific calculation method of the arithmetic mean surface roughness (Ra) is as described in the examples.
Under the conditions of a temperature of 23 ± 2 ° C. and a relative humidity of 30 ± 5%, only the electrode sample in this measurement sample was raised vertically at 10 mm / min using a tensile compression tester to obtain an electrode sample. The weight when rising 10 mm in the vertical direction is measured. This measurement is performed three times to calculate the average value.
This average value is divided by the area of the overlapping portion of the electrode sample and the ion exchange membrane and the mass of the electrode sample of the portion overlapping with the ion exchange membrane, and the applied force per unit mass / unit area (1) (N). / Mg · cm ² ) is calculated.

The force (1) applied per unit mass / unit area obtained by the method (i) has good handleability, and is coated with a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode, and a catalyst coating. From the viewpoint of having good adhesion to a non-feeding body, it is preferably 1.6 N / (mg · cm ² ) or less, more preferably less than 1.6 N / (mg · cm ² ), and further. It is preferably less than 1.5 N / (mg · cm ² ), more preferably 1.2 N / mg · cm ² or less, and even more preferably 1.20 N / mg · cm ² or less. It is even more preferably 1.1 N / mg · cm ² or less, even more preferably 1.10 N / mg · cm ² or less, and particularly preferably 1.0 N / mg · cm ² or less, 1.00 N. It is particularly preferable that it is / mg · cm ² or less. Further, from the viewpoint of further improving the electrolytic performance, it is preferably more than 0.005 N / (mg · cm ² ), more preferably 0.08 N / (mg · cm ² ) or more, and further preferably 0. It is more preferably 1 N / (mg · cm ² ) or more, and more preferably 0.14 N / (mg) from the viewpoint of facilitating handling in a large size (for example, size 1.5 m × 2.5 m). -Cm ² ), more preferably 0.2 N / (mg · cm ² ) or more.

[Method (ii)]
A nickel plate (thickness 1.2 mm, 200 mm square, nickel plate similar to the above method (i)) obtained by blasting with alumina having a grain number of 320 and an electrode sample (130 mm square) are laminated in this order. After the laminate is sufficiently immersed in pure water, excess water adhering to the surface of the laminate is removed to obtain a measurement sample. Under the conditions of a temperature of 23 ± 2 ° C. and a relative humidity of 30 ± 5%, only the electrode sample in this measurement sample was raised vertically at 10 mm / min using a tensile compression tester to obtain an electrode sample. , Measure the weight when rising 10 mm in the vertical direction. This measurement is performed three times to calculate the average value.
Dividing this average value by the area of the overlapping portion of the electrode sample and the nickel plate and the mass of the electrode sample in the overlapping portion of the nickel plate, the unit mass / adhesive force per unit area (2) (N / mg)・ Calculate cm ² ).

The force (2) applied per unit mass / unit area obtained by method (ii) has good handleability, and is coated with diaphragms such as ion exchange membranes and microporous membranes, deteriorated electrodes, and catalyst coatings. From the viewpoint of having good adhesion to a non-feeding body, it is preferably 1.6 N / (mg · cm ² ) or less, more preferably less than 1.6 N / (mg · cm ² ), and further. It is preferably less than 1.5 N / (mg · cm ² ), more preferably 1.2 N / mg · cm ² or less, and even more preferably 1.20 N / mg · cm ² or less. It is even more preferably 1.1 N / mg · cm ² or less, even more preferably 1.10 N / mg · cm ² or less, and particularly preferably 1.0 N / mg · cm ² or less, 1.00 N. It is particularly preferable that it is / mg · cm ² or less. Further, from the viewpoint of further improving the electrolytic performance, it is preferably more than 0.005 N / (mg · cm ² ), more preferably 0.08 N / (mg · cm ² ) or more, and further preferably 0. It is 1 N / (mg · cm ² ) or more, more preferably 0. From the viewpoint of facilitating handling in a large size (for example, size 1.5 m × 2.5 m). It is 14 N / (mg · cm ² ) or more.

The electrode for electrolysis in the present embodiment preferably includes an electrode base material for electrolysis and a catalyst layer. The thickness (gauge thickness) of the electrode base material for electrolysis is not particularly limited, but good handleability is obtained, and a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (feeding body), and a catalyst coating are applied. It has good adhesion to the electrode (feeding body) that has not been used, can be rolled into a suitable roll, can be bent well, and can be easily handled in a large size (for example, size 1.5m x 2.5m). From the viewpoint, 300 μm or less is preferable, 205 μm or less is more preferable, 155 μm or less is further preferable, 135 μm or less is further preferable, 125 μm or less is further preferable, 120 μm or less is further preferable, and 100 μm or less is further preferable. From the viewpoint of handleability and economy, 50 μm or less is even more preferable. The lower limit is not particularly limited, but is, for example, 1 μm, preferably 5 μm, and more preferably 15 μm.

In the present embodiment, in order to integrate the new diaphragm and the electrode for electrolysis, it is preferable that a liquid is interposed between them. The liquid can be any liquid such as water and an organic solvent as long as it generates surface tension. The larger the surface tension of the liquid, the greater the force applied between the new diaphragm and the electrode for electrolysis. Therefore, a liquid having a large surface tension is preferable. Examples of the liquid include the following (the numerical value in parentheses is the surface tension of the liquid at 20 ° C.).
Hexane (20.44mN / m), Acetone (23.30mN / m), Methanol (24.00mN / m), Ethanol (24.05mN / m), Ethylene Glycol (50.21mN / m) Water (72.76mN) / M)
In the case of a liquid having a large surface tension, a new diaphragm and an electrode for electrolysis tend to be integrated (a laminate), and the electrode renewal tends to be easier. The amount of liquid between the new diaphragm and the electrode for electrolysis may be such that they stick to each other due to surface tension, and as a result, the amount of liquid is small. It does not affect the electrolysis itself.
From the viewpoint of practical use, it is preferable to use a liquid having a surface tension of 24 mN / m to 80 mN / m, such as ethanol, ethylene glycol, and water. In particular, water or an aqueous solution obtained by dissolving caustic soda, potassium hydroxide, lithium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium carbonate, potassium carbonate or the like in water to make it alkaline is preferable. Further, the surface tension can be adjusted by impregnating these liquids with a surfactant. By including the surfactant, the adhesiveness between the new diaphragm and the electrode for electrolysis is changed, and the handleability can be adjusted. The surfactant is not particularly limited, and either an ionic surfactant or a nonionic surfactant can be used.

The electrode for electrolysis in the present embodiment is not particularly limited, but good handleability is obtained, and a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (feeding body), and an electrode without catalyst coating (feeding) are obtained. From the viewpoint of having good adhesive strength with the body), the ratio measured by the following method (2) is preferably 90% or more, more preferably 92% or more, and further, a large size (large size (2)). For example, it is more preferably 95% or more from the viewpoint of facilitating handling in a size of 1.5 m × 2.5 m). The upper limit is 100%.

[Method (2)]
The ion exchange membrane (170 mm square) and the electrode sample (130 mm square) are laminated in this order. Under the conditions of a temperature of 23 ± 2 ° C. and a relative humidity of 30 ± 5%, the laminate was placed on a curved surface of a polyethylene pipe (outer diameter 280 mm) so that the electrode sample in the laminate was on the outside, and the laminate was placed. The pipe is sufficiently immersed in pure water to remove excess water adhering to the surface of the laminate and the pipe, and one minute later, the portion where the ion exchange membrane (170 mm square) and the electrode sample are in close contact with each other. Measure the percentage of the area of.

The electrode for electrolysis in the present embodiment is not particularly limited, but good handleability is obtained, and a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (feeding body), and an electrode without catalyst coating (feeding) are obtained. From the viewpoint that it has good adhesive strength to the body), can be appropriately rolled into a roll, and can be bent satisfactorily, the ratio measured by the following method (3) is preferably 75% or more. It is more preferably 80% or more, and further preferably 90% or more from the viewpoint of facilitating handling in a large size (for example, size 1.5 m × 2.5 m). The upper limit is 100%.
[Method (3)]
The ion exchange membrane (170 mm square) and the electrode sample (130 mm square) are laminated in this order. Under the conditions of a temperature of 23 ± 2 ° C. and a relative humidity of 30 ± 5%, the laminate was placed on a curved surface of a polyethylene pipe (outer diameter 145 mm) so that the electrode sample in the laminate was on the outside, and the laminate was placed. The pipe is sufficiently immersed in pure water to remove excess water adhering to the surface of the laminate and the pipe, and one minute later, the portion where the ion exchange membrane (170 mm square) and the electrode sample are in close contact with each other. Measure the percentage of the area of.

The electrode for electrolysis in the present embodiment is not particularly limited, but good handleability is obtained, and a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode (feeding body), and an electrode without catalyst coating (feeding) are obtained. It has a good adhesive force with the body), and from the viewpoint of preventing the retention of gas generated during electrolysis, it is preferably a porous structure having a porosity or a porosity of 5 to 90% or less. The opening rate is more preferably 10 to 80% or less, still more preferably 20 to 75%.
The opening rate is the ratio of the opening portion per unit volume. There are various calculation methods depending on whether the opening is also considered to the submicron order or only the visible opening. In the present embodiment, the opening ratio A can be calculated by the following formula by calculating the volume V from the values of the gauge thickness, width, and length of the electrode and further measuring the weight W.
A = (1- (W / (V × ρ)) × 100
ρ is the density of the electrode material (g / cm ³ ). For example, in the case of nickel, it is 8.908 g / cm ³ , and in the case of titanium, it is 4.506 g / cm ³ . The opening ratio can be adjusted by changing the area where the metal is punched out per unit area for punching metal, changing the SW (minor diameter), LW (major diameter), and feed values for expanded metal, or mesh. Changes the wire diameter and number of meshes of metal fibers, changes the pattern of the photoresist used for electroforming, changes the metal fiber diameter and fiber density for non-woven materials, and forms voids for foamed metals. It can be appropriately adjusted by a method such as changing the mold for making the metal.

Hereinafter, a more specific embodiment of the electrode for electrolysis in the present embodiment will be described.
The electrode for electrolysis according to the present embodiment preferably includes an electrode base material for electrolysis and a catalyst layer. The catalyst layer may be composed of a plurality of layers or may have a single layer structure as described below.
As shown in FIG. 6, the electrolysis electrode 100 according to the present embodiment includes an electrolysis electrode base material 10 and a pair of first layers 20 that cover both surfaces of the electrolysis electrode base material 10. The first layer 20 preferably covers the entire electrode base material 10 for electrolysis. This makes it easy to improve the catalytic activity and durability of the electrode for electrolysis. The first layer 20 may be laminated only on one surface of the electrode base material 10 for electrolysis.
Further, as shown in FIG. 6, the surface of the first layer 20 may be covered with the second layer 30. The second layer 30 preferably covers the entire first layer 20. Further, the second layer 30 may be laminated on only one surface of the first layer 20.

(Electrode substrate for electrolysis)
The electrolytic electrode base material 10 is not particularly limited, but for example, a valve metal typified by nickel, nickel alloy, stainless steel, titanium and the like can be used, and from nickel (Ni) and titanium (Ti). It preferably contains at least one element of choice.
Considering that iron and chromium elute when stainless steel is used in a high-concentration alkaline aqueous solution, and that the electrical conductivity of stainless steel is about 1/10 that of nickel, it can be used as an electrode base material for electrolysis. A substrate containing nickel (Ni) is preferred.
Further, it is also preferable that the electrode base material 10 for electrolysis is made of titanium having high corrosion resistance when used in a chlorine gas generating atmosphere in a salt solution having a concentration close to saturation.
The shape of the electrode base material 10 for electrolysis is not particularly limited, and an appropriate shape can be selected depending on the purpose. As the shape, any of punching metal, non-woven fabric, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting a metal wire, and the like can be used. Of these, punching metal or expanded metal is preferable. Electroforming is a technique for producing a metal thin film having a precise pattern by combining photoengraving and electroplating. This is a method of forming a pattern on a substrate with a photoresist and electroplating a portion not protected by the resist to obtain a thin metal.
Regarding the shape of the electrode base material for electrolysis, there are suitable specifications depending on the distance between the anode and the cathode in the electrolytic cell. Although not particularly limited, when the anode and the cathode have a finite distance, an expanded metal or punching metal shape can be used, and in the case of a so-called zero gap electrolytic cell in which the ion exchange film and the electrode are in contact with each other. Woven mesh woven with fine wires, wire mesh, foam metal, metal anode, expanded metal, punching metal, metal porous foil and the like can be used.
Examples of the electrode base material 10 for electrolysis include a metal porous foil, a wire mesh, a metal non-woven fabric, a punching metal, an expanded metal, and a foamed metal.
As the plate material before being processed into a punching metal or an expanded metal, a rolled plate material, an electrolytic foil or the like is preferable. It is preferable that the electrolytic foil is further plated with the same element as the base material as a post-treatment to make unevenness on one side or both sides.
Further, as described above, the thickness of the electrode base material 10 for electrolysis is preferably 300 μm or less, more preferably 205 μm or less, further preferably 155 μm or less, and further preferably 135 μm or less. It is more preferably 125 μm or less, further preferably 120 μm or less, further preferably 100 μm or less, and even more preferably 50 μm or less from the viewpoint of handleability and economy. preferable. The lower limit is not particularly limited, but is, for example, 1 μm, preferably 5 μm, and more preferably 15 μm.

In the electrode base material for electrolysis, it is preferable to relax the residual stress during processing by annealing the electrode base material for electrolysis in an oxidizing atmosphere. Further, in order to improve the adhesion to the catalyst layer coated on the surface of the electrode base material for electrolysis, unevenness is formed by using a steel grid, alumina powder, etc., and then the surface area is increased by acid treatment. It is preferable to increase it. Alternatively, it is preferable to perform plating treatment with the same element as the base material to increase the surface area.

It is preferable that the electrode base material 10 for electrolysis is subjected to a treatment for increasing the surface area in order to bring the first layer 20 and the surface of the electrode base material 10 for electrolysis into close contact with each other. Examples of the treatment for increasing the surface area include a blast treatment using a cut wire, a steel grid, an alumina grid, etc., an acid treatment using sulfuric acid or hydrochloric acid, a plating treatment using the same element as the base material, and the like. The arithmetic mean surface roughness (Ra) of the substrate surface is not particularly limited, but is preferably 0.05 μm to 50 μm, more preferably 0.1 to 10 μm, and even more preferably 0.1 to 8 μm.

Next, a case where the electrode for electrolysis in this embodiment is used as an anode for salt electrolysis will be described.
(First layer)
In FIG. 6, the first layer 20 which is a catalyst layer contains at least one kind of oxide among ruthenium oxide, iridium oxide and titanium oxide. Examples of the ruthenium oxide include RuO ₂ . Examples of the iridium oxide include IrO ₂ . Examples of the titanium oxide include TiO ₂ and the like. The first layer 20 preferably contains two types of oxides, ruthenium oxide and titanium oxide, or preferably contains three types of oxides, ruthenium oxide, iridium oxide and titanium oxide. As a result, the first layer 20 becomes a more stable layer, and the adhesion with the second layer 30 is further improved.

When the first layer 20 contains two types of oxides, a ruthenium oxide and a titanium oxide, the titanium oxidation contained in the first layer 20 is compared with 1 mol of the ruthenium oxide contained in the first layer 20. The substance is preferably 1 to 9 mol, more preferably 1 to 4 mol. By setting the composition ratio of the two types of oxides in this range, the electrode 100 for electrolysis exhibits excellent durability.

When the first layer 20 contains three types of oxides, ruthenium oxide, iridium oxide and titanium oxide, it is contained in the first layer 20 with respect to 1 mol of the ruthenium oxide contained in the first layer 20. The iridium oxide is preferably 0.2 to 3 mol, more preferably 0.3 to 2.5 mol. Further, the titanium oxide contained in the first layer 20 is preferably 0.3 to 8 mol, and more preferably 1 to 7 mol, with respect to 1 mol of the ruthenium oxide contained in the first layer 20. preferable. By setting the composition ratio of the three types of oxides in this range, the electrode 100 for electrolysis exhibits excellent durability.

When the first layer 20 contains at least two kinds of oxides selected from ruthenium oxide, iridium oxide and titanium oxide, these oxides preferably form a solid solution. By forming the oxide solid solution, the electrode 100 for electrolysis exhibits excellent durability.

In addition to the above compositions, various compositions can be used as long as they contain at least one of ruthenium oxide, iridium oxide and titanium oxide. For example, an oxide coating containing ruthenium, iridium, tantalum, niobium, titanium, tin, cobalt, manganese, platinum and the like, which is called DSA (registered trademark), can be used as the first layer 20.

The first layer 20 does not have to be a single layer and may include a plurality of layers. For example, the first layer 20 may include a layer containing three types of oxides and a layer containing two types of oxides. The thickness of the first layer 20 is preferably 0.05 to 10 μm, more preferably 0.1 to 8 μm.

(Second layer)
The second layer 30 preferably contains ruthenium and titanium. This makes it possible to further reduce the chlorine overvoltage immediately after electrolysis.

The second layer 30 preferably contains palladium oxide, a solid solution of palladium oxide and platinum, or an alloy of palladium and platinum. This makes it possible to further reduce the chlorine overvoltage immediately after electrolysis.

The thicker the second layer 30, the longer the period during which the electrolytic performance can be maintained, but from the economical point of view, the thickness of the second layer 30 is preferably 0.05 to 3 μm.

Next, a case where the electrode for electrolysis in this embodiment is used as a cathode for salt electrolysis will be described.
(First layer)
The components of the first layer 20 which is the catalyst layer include C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, and Ru. , Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb, Lu and the like, and oxides or hydroxides of the metal.
It may or may not contain at least one kind of an alloy containing a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and a platinum group metal.
When at least one of a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and an alloy containing a platinum group metal is contained, the platinum group metal, the platinum group metal oxide, the platinum group metal hydroxide, and the platinum group It is preferable that the metal-containing alloy contains at least one platinum group metal among platinum, palladium, rhodium, ruthenium and iridium.
The platinum group metal preferably contains platinum.
The platinum group metal oxide preferably contains ruthenium oxide.
The platinum group metal hydroxide preferably contains ruthenium hydroxide.
The platinum group metal alloy preferably contains an alloy of platinum with nickel, iron, and cobalt.
Further, it is preferable to contain an oxide of a lanthanoid element or a hydroxide as a second component, if necessary. As a result, the electrode 100 for electrolysis exhibits excellent durability.
The oxide or hydroxide of the lanthanoid element preferably contains at least one selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, and dysprosium.
Further, if necessary, it is preferable to include a transition metal oxide or a hydroxide as the third component.
By adding the third component, the electrolytic electrode 100 exhibits better durability and can reduce the electrolytic voltage.
Examples of preferred combinations are ruthenium only, ruthenium + nickel, ruthenium + cerium, ruthenium + lanthanum, ruthenium + lanthanum + platinum, ruthenium + lanthanum + palladium, ruthenium + placeodium, ruthenium + placeodium + platinum, ruthenium + placeodium + platinum + Palladium, ruthenium + neodym, ruthenium + neodym + platinum, ruthenium + neodym + manganese, ruthenium + neodym + iron, ruthenium + neodymium + cobalt, ruthenium + neodymium + zinc, ruthenium + neodymium + gallium, ruthenium + neodymium + sulfur, ruthenium + Neogym + lead, ruthenium + neodym + nickel, ruthenium + neodym + copper, ruthenium + samarium, ruthenium + samarium + manganese, ruthenium + samarium + iron, ruthenium + samarium + cobalt, ruthenium + samarium + zinc, ruthenium + samarium + gallium, Ruthenium + samarium + sulfur, ruthenium + samarium + lead, ruthenium + samarium + nickel, platinum + cerium, platinum + palladium + cerium, platinum + palladium + lanthanum + cerium, platinum + iridium, platinum + palladium, platinum + iridium + palladium, Examples include platinum + nickel + palladium, platinum + nickel + ruthenium, platinum-nickel alloys, platinum-cobalt alloys, platinum-iron alloys, and the like.
When an alloy containing a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, or a platinum group metal is not contained, it is preferable that the main component of the catalyst is a nickel element.
It is preferable to contain at least one of nickel metal, oxide and hydroxide.
A transition metal may be added as the second component. The second component to be added preferably contains at least one element of titanium, tin, molybdenum, cobalt, manganese, iron, sulfur, zinc, copper and carbon.
Preferred combinations include nickel + tin, nickel + titanium, nickel + molybdenum, nickel + cobalt and the like.
If necessary, an intermediate layer can be provided between the first layer 20 and the electrode base material 10 for electrolysis. By installing the intermediate layer, the durability of the electrolytic electrode 100 can be improved.
As the intermediate layer, those having an affinity for both the first layer 20 and the electrode base material 10 for electrolysis are preferable. As the intermediate layer, nickel oxide, platinum group metal, platinum group metal oxide, and platinum group metal hydroxide are preferable. The intermediate layer can be formed by applying and firing a solution containing a component forming the intermediate layer, or by heat-treating the substrate in an air atmosphere at a temperature of 300 to 600 ° C. to oxidize the surface. It is also possible to form a material layer. In addition, it can be formed by a known method such as a thermal spraying method or an ion plating method.

(Second layer)
The components of the first layer 30 which is the catalyst layer include C, Si, P, S, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, and Ru. , Rh, Pd, Ag, Cd, In, Sn, Ta, W, Re, Os, Ir, Pt, Au, Hg, Pb, Bi, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb, Lu and the like, and oxides or hydroxides of the metal.
It may or may not contain at least one kind of an alloy containing a platinum group metal, a platinum group metal oxide, a platinum group metal hydroxide, and a platinum group metal. Examples of preferable combinations of elements contained in the second layer include the combinations mentioned in the first layer. The combination of the first layer and the second layer may be a combination having the same composition but a different composition ratio, or a combination having different compositions.

As the thickness of the catalyst layer, the total thickness of the formed catalyst layer and the intermediate layer is preferably 0.01 μm to 20 μm. If it is 0.01 μm or more, it can sufficiently function as a catalyst. When the thickness is 20 μm or less, a strong catalyst layer can be formed with little loss from the substrate. More preferably, 0.05 μm to 15 μm. More preferably, it is 0.1 μm to 10 μm. More preferably, it is 0.2 μm to 8 μm.

The thickness of the electrode, that is, the total thickness of the electrode base material for electrolysis and the catalyst layer, is preferably 315 μm or less, more preferably 220 μm or less, further preferably 170 μm or less, and further preferably 150 μm or less from the viewpoint of handleability of the electrode. More preferably, 145 μm or less is particularly preferable, 140 μm or less is further preferable, 138 μm or less is further preferable, and 135 μm or less is further preferable. If it is 135 μm or less, good handleability can be obtained. Further, from the same viewpoint as above, it is preferably 130 μm or less, more preferably less than 130 μm, further preferably 115 μm or less, still more preferably 65 μm or less. The lower limit is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 20 μm or more from a practical point of view. The thickness of the electrode can be determined by measuring with a Digimatic Sixness Gauge (Mitutoyo Co., Ltd., minimum display 0.001 mm). The thickness of the electrode base material for electrodes is measured in the same manner as the electrode thickness. The catalyst layer thickness can be obtained by subtracting the thickness of the electrode base material for electrolysis from the electrode thickness.

In the present embodiment, from the viewpoint of ensuring sufficient electrolytic performance, the electrolytic electrodes are Ru, Rh, Pd, Ir, Pt, Au, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ag, Ta, W, Re, Os, Al, In, Sn, Sb, Ga, Ge, B, C, N, O, Si, P, S, La, Ce, Pr, It preferably contains at least one catalytic component selected from the group consisting of Nd, Pm, Sm, Eu, Gd, Tb and Dy.

In the present embodiment, when the electrode for electrolysis is an electrode having a wide elastic deformation region, better handleability can be obtained, and a diaphragm such as an ion exchange membrane or a microporous membrane, a deteriorated electrode, and a catalyst coating are not applied. From the viewpoint of having better adhesion to the feeder and the like, the thickness of the electrode for electrolysis is preferably 315 μm or less, more preferably 220 μm or less, further preferably 170 μm or less, further preferably 150 μm or less, and particularly preferably 145 μm or less. , 140 μm or less is more preferable, 138 μm or less is even more preferable, and 135 μm or less is even more preferable. If it is 135 μm or less, good handleability can be obtained. Further, from the same viewpoint as above, 130 μm or less is preferable, less than 130 μm is more preferable, 115 μm or less is further preferable, and 65 μm or less is further preferable. The lower limit is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 20 μm or more from a practical point of view. In the present embodiment, "the elastic deformation region is wide" means that the electrolytic electrode is wound to form a wound body, and after the wound state is released, warpage due to the winding is unlikely to occur. .. Further, the thickness of the electrode for electrolysis means the total thickness of the electrode base material for electrolysis and the catalyst layer when the catalyst layer described later is included.

(Manufacturing method of electrode for electrolysis)
Next, an embodiment of a method for manufacturing the electrolytic electrode 100 will be described in detail.
In the present embodiment, the first layer 20, preferably the second layer, is placed on the electrode substrate for electrolysis by a method such as firing (thermal decomposition) of the coating film in an oxygen atmosphere, ion plating, plating, or thermal spraying. By forming 30, the electrode 100 for electrolysis can be manufactured. In such a manufacturing method of the present embodiment, high productivity of the electrode 100 for electrolysis can be realized. Specifically, a catalyst layer is formed on the electrode substrate for electrolysis by a coating step of applying a coating liquid containing a catalyst, a drying step of drying the coating liquid, and a thermal decomposition step of performing thermal decomposition. Here, thermal decomposition means that a metal salt as a precursor is heated and decomposed into a metal or a metal oxide and a gaseous substance. Decomposition products differ depending on the type of metal used, the type of salt, the atmosphere in which thermal decomposition is performed, and the like, but in an oxidizing atmosphere, many metals tend to form oxides easily. In the industrial manufacturing process of electrodes, pyrolysis is usually carried out in air, often forming metal oxides or metal hydroxides.

(Formation of the first layer of the anode)
(Applying process)
In the first layer 20, a solution (first coating liquid) in which at least one metal salt of ruthenium, iridium and titanium is dissolved is applied to an electrode base material for electrolysis, and then thermally decomposed (baked) in the presence of oxygen. Can be obtained. The content of ruthenium, iridium and titanium in the first coating liquid is substantially the same as that of the first layer 20.

The metal salt may be in any form such as chloride salt, nitrate, sulfate, metal alkoxide and the like. The solvent of the first coating liquid can be selected depending on the type of the metal salt, but water, alcohols such as butanol, and the like can be used. As the solvent, water or a mixed solvent of water and alcohols is preferable. The total metal concentration in the first coating liquid in which the metal salt is dissolved is not particularly limited, but is preferably in the range of 10 to 150 g / L in consideration of the thickness of the coating film formed by one coating.

As a method of applying the first coating liquid on the electrode base material 10 for electrolysis, a dip method of immersing the electrode base material 10 for electrolysis in the first coating liquid, a method of applying the first coating liquid with a brush, and a first coating liquid. A roll method using a sponge-like roll impregnated with the above, an electrostatic coating method in which the electrode base material 10 for electrolysis and the first coating liquid are charged with opposite charges and spray sprayed are used. Among these, the roll method or the electrostatic coating method, which is excellent in industrial productivity, is preferable.

(Drying process, pyrolysis process)
After applying the first coating liquid to the electrode base material 100 for electrolysis, it is dried at a temperature of 10 to 90 ° C. and thermally decomposed in a firing furnace heated to 350 to 650 ° C. Temporary firing may be performed at 100-350 ° C., if necessary, between drying and pyrolysis. The drying, temporary firing and thermal decomposition temperatures can be appropriately selected depending on the composition of the first coating liquid and the solvent type. It is preferable that the time for each thermal decomposition is long, but from the viewpoint of electrode productivity, 3 to 60 minutes is preferable, and 5 to 20 minutes is more preferable.

The above cycle of coating, drying and thermal decomposition is repeated to form a coating (first layer 20) to a predetermined thickness. After forming the first layer 20, if necessary, firing is performed for a longer period of time and then heating is performed, so that the stability of the first layer 20 can be further enhanced.

(Formation of the second layer)
The second layer 30 is formed as needed, and for example, after applying a solution containing a palladium compound and a platinum compound or a solution containing a ruthenium compound and a titanium compound (second coating liquid) onto the first layer 20, the second layer 30 is formed. Obtained by thermal decomposition in the presence of oxygen.

(Formation of the first layer of the cathode by the thermal decomposition method)
(Applying process)
The first layer 20 is obtained by applying a solution (first coating liquid) in which various combinations of metal salts are dissolved to an electrode base material for electrolysis, and then thermally decomposing (baking) in the presence of oxygen. The content of the metal in the first coating liquid is substantially the same as that of the first layer 20.

The metal salt may be in any form such as chloride salt, nitrate, sulfate, metal alkoxide and the like. The solvent of the first coating liquid can be selected depending on the type of the metal salt, but water, alcohols such as butanol, and the like can be used. As the solvent, water or a mixed solvent of water and alcohols is preferable. The total metal concentration in the first coating liquid in which the metal salt is dissolved is not particularly limited, but is preferably in the range of 10 to 150 g / L in consideration of the thickness of the coating film formed by one coating.

As a method of applying the first coating liquid on the electrode base material 10 for electrolysis, a dip method of immersing the electrode base material 10 for electrolysis in the first coating liquid, a method of applying the first coating liquid with a brush, and a first coating liquid. A roll method using a sponge-like roll impregnated with the above, an electrostatic coating method in which the electrode base material 10 for electrolysis and the first coating liquid are charged with opposite charges and spray sprayed are used. Among these, the roll method or the electrostatic coating method, which is excellent in industrial productivity, is preferable.

(Drying process, pyrolysis process)
After the first coating liquid is applied to the electrode base material 10 for electrolysis, it is dried at a temperature of 10 to 90 ° C. and thermally decomposed in a firing furnace heated to 350 to 650 ° C. Temporary firing may be performed at 100-350 ° C., if necessary, between drying and pyrolysis. The drying, temporary firing and thermal decomposition temperatures can be appropriately selected depending on the composition of the first coating liquid and the solvent type. It is preferable that the time for each thermal decomposition is long, but from the viewpoint of electrode productivity, 3 to 60 minutes is preferable, and 5 to 20 minutes is more preferable.

The above cycle of coating, drying and thermal decomposition is repeated to form a coating (first layer 20) to a predetermined thickness. After forming the first layer 20, if necessary, firing is performed for a longer period of time and then heating is performed, so that the stability of the first layer 20 can be further enhanced.

(Formation of intermediate layer)
The intermediate layer is formed as needed, and is obtained, for example, by applying a solution containing a palladium compound or a platinum compound (second coating solution) onto a substrate and then thermally decomposing it in the presence of oxygen. Alternatively, the nickel oxide intermediate layer may be formed on the surface of the substrate simply by heating the substrate without applying the solution.

(Formation of the first layer of the cathode by ion plating)
The first layer 20 can also be formed by ion plating.
One example is a method of fixing a substrate in a chamber and irradiating a metallic ruthenium target with an electron beam. The evaporated metallic ruthenium particles are positively charged in the plasma in the chamber and deposited on the negatively charged substrate. The plasma atmosphere is argon and oxygen, and ruthenium is deposited on the substrate as ruthenium oxide.

(Formation of the first layer of the cathode by plating)
The first layer 20 can also be formed by a plating method.
As an example, when a substrate is used as a cathode and electrolytic plating is performed in an electrolytic solution containing nickel and tin, an alloy plating of nickel and tin can be formed.

(Formation of the first layer of the cathode by thermal spraying)
The first layer 20 can also be formed by a thermal spraying method.
As an example, by plasma spraying nickel oxide particles onto a substrate, a catalyst layer in which metallic nickel and nickel oxide are mixed can be formed.

Hereinafter, the ion exchange membrane according to one aspect of the diaphragm will be described in detail.
[Ion exchange membrane]
The ion exchange membrane is not particularly limited as long as it can be a laminate with an electrode for electrolysis, and various ion exchange membranes can be applied. In the present embodiment, an ion exchange membrane having a hydrocarbon-based polymer having an ion-exchange group or a membrane body containing a fluorine-containing polymer and a coating layer provided on at least one surface of the membrane body is used. Is preferable. Further, the coating layer contains inorganic particles and a binder, and the specific surface area of the coating layer is preferably 0.1 to 10 m ² / g. The ion exchange membrane having such a structure has little influence on the electrolysis performance due to the gas generated during electrolysis, and tends to exhibit stable electrolysis performance.
The film of the perfluorocarbon polymer into which the ion exchange group has been introduced is a sulfonic acid having an ion exchange group derived from a sulfo group (a group represented by _−SO3- , hereinafter also referred to as a “sulfonic acid group”). It comprises one of a layer and a carboxylic acid layer having an ion exchange group derived from a carboxyl group (a group represented by −CO _2- , hereinafter also referred to as a “carboxylic acid group”). From the viewpoint of strength and dimensional stability, it is preferable to further have a reinforced core material.
Inorganic particles and binders will be described in detail below in the description section of the coating layer.

FIG. 7 is a schematic cross-sectional view showing an embodiment of an ion exchange membrane. The ion exchange membrane 1 has a membrane body 10 containing a hydrocarbon-based polymer or a fluorine-containing polymer having an ion exchange group, and coating layers 11a and 11b formed on both sides of the film body 10.

In the ion exchange film 1, the film body 10 is derived from a sulfonic acid layer 3 having an ion exchange group derived from a sulfo group (a group represented by _−SO3- ^, hereinafter also referred to as a “sulfonic acid group”) and a carboxyl group. It is provided with a carboxylic acid layer 2 having an ion exchange group (a group represented by −CO _2- ^, hereinafter also referred to as a “carboxylic acid group”), and the strength and dimensional stability are enhanced by the reinforced core material 4. .. Since the ion exchange membrane 1 includes the sulfonic acid layer 3 and the carboxylic acid layer 2, it is suitably used as a cation exchange membrane.

The ion exchange membrane may have only one of a sulfonic acid layer and a carboxylic acid layer. Further, the ion exchange membrane does not necessarily have to be reinforced by the reinforced core material, and the arrangement state of the reinforced core material is not limited to the example of FIG. 7.

(Membrane body)
First, the membrane body 10 constituting the ion exchange membrane 1 will be described.
The film body 10 has a function of selectively permeating cations, and may contain a hydrocarbon-based polymer or a fluorine-containing polymer having an ion exchange group, and its composition and material are particularly limited. However, a suitable one can be appropriately selected.

The hydrocarbon-based polymer or fluorine-containing polymer having an ion-exchange group in the film body 10 is, for example, a hydrocarbon-based polymer or a fluorine-containing weight having an ion-exchange group precursor that can become an ion-exchange group by hydrolysis or the like. Can be obtained from coalescence. Specifically, for example, the main chain is made of a fluorinated hydrocarbon, has a group that can be converted into an ion exchange group by hydrolysis or the like (ion exchange group precursor) as a pendant side chain, and can be melted. After preparing a precursor of the membrane body 10 using a polymer (hereinafter, sometimes referred to as “fluorine-containing polymer (a)”), the ion exchange group precursor is converted into an ion exchange group to form a film. The main body 10 can be obtained.

The fluoropolymer (a) contains, for example, at least one monomer selected from the first group below and at least one monomer selected from the second group and / or the third group below. It can be produced by copolymerizing. Further, it can also be produced by homopolymerization of one kind of monomer selected from any of the following 1st group, the following 2nd group, and the following 3rd group.

Examples of the first group of monomers include vinyl fluoride compounds. Examples of the vinyl fluoride compound include vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoroalkyl vinyl ether and the like. In particular, when an ion exchange membrane is used as a membrane for alkaline electrolysis, the vinyl fluoride compound is preferably a perfluoromonomer, and is selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, and perfluoroalkylvinyl ether. Fluoromonomers are preferred.

Examples of the second group of monomers include vinyl compounds having a functional group that can be converted into a carboxylic acid type ion exchange group (carboxylic acid group). Examples of the vinyl compound having a functional group that can be converted into a carboxylic acid group include a monomer represented by CF ₂ = CF (OCF ₂ CYF) _s -O (CZF) _t -COOR (here). , S represent an integer of 0 to 2, t represents an integer of 1 to 12, Y and Z each independently represent F or CF ₃ , and R represents a lower alkyl group. , For example, an alkyl group having 1 to 3 carbon atoms.).

Among these, a compound represented by CF ₂ = CF (OCF ₂ CYF) _n -O (CF ₂ ) _m -COOR is preferable. Here, n represents an integer of 0 to 2, m represents an integer of 1 to 4, Y represents F or CF ₃ , and R represents CH ₃ , C ₂ H ₅ , or C ₃ H ₇ .

When the ion exchange film is used as the cation exchange film for alkaline electrolysis, it is preferable to use at least a perfluoro compound as the monomer, but the alkyl group of the ester group (see R above) is heavy at the time of hydrolysis. The alkyl group (R) does not have to be a perfluoroalkyl group in which all hydrogen atoms are substituted with fluorine atoms, as it is lost from coalescence.

Among the above, the monomers represented below are more preferable as the second group of monomers.
CF ₂ = CFOCF ₂ -CF (CF ₃ ) OCF ₂ COOCH ₃ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ COOCH ₃ ,
CF ₂ = CF [OCF ₂ -CF (CF ₃ )] ₂ O (CF ₂ ) ₂ COOCH ₃ ,
CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ COOCH ₃ ,
CF ₂ = CFO (CF ₂ ) ₂ COOCH ₃ ,
CF ₂ = CFO (CF ₂ ) ₃ COOCH ₃ .

Examples of the monomer of the third group include vinyl compounds having a functional group that can be converted into a sulfonic acid type ion exchange group (sulfonic acid group). As the vinyl compound having a functional group that can be converted into a sulfonic acid group, for example, a monomer represented by CF ₂ = CFO-X-CF ₂ -SO _2F is preferable (where X is a perfluoroalkylene group). Represents.). Specific examples of these include the monomers represented below.
CF ₂ = CFOCF ₂ CF ₂ SO ₂ F,
CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F,
CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ CF ₂ SO ₂ F,
CF ₂ = CF (CF ₂ ) ₂ SO ₂ F,
CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] ₂ CF ₂ CF ₂ SO ₂ F,
CF ₂ = CFOCF ₂ CF (CF ₂ OCF ₃ ) OCF ₂ CF ₂ SO ₂ F.

Of these, CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ CF ₂ SO ₂ F and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F are more preferable.

The copolymer obtained from these monomers can be produced by a polymerization method developed for homopolymerization and copolymerization of ethylene fluoride, particularly a general polymerization method used for tetrafluoroethylene. .. For example, in the non-aqueous method, an inert solvent such as perfluorohydrocarbon or chlorofluorocarbon is used, and in the presence of a radical polymerization initiator such as perfluorocarbon peroxide or an azo compound, the temperature is 0 to 200 ° C. and the pressure is 0. The polymerization reaction can be carried out under the condition of 1 to 20 MPa.

In the above-mentioned copolymerization, the type of the combination of the above-mentioned monomers and the ratio thereof are not particularly limited, and are selectively determined by the type and the amount of the functional group to be imparted to the obtained fluorine-containing polymer. For example, in the case of a fluorine-containing polymer containing only a carboxylic acid group, at least one monomer of each of the first group and the second group may be selected and copolymerized. Further, in the case of a fluorine-containing polymer containing only a sulfonic acid group, at least one monomer of each of the first group and third group monomers may be selected and copolymerized. Further, in the case of a fluoropolymer having a carboxylic acid group and a sulfonic acid group, at least one monomer is selected from the monomers of the first group, the second group and the third group, and the copolymer is used. It may be polymerized. In this case, the desired fluorocarbon-containing system can also be obtained by separately polymerizing the copolymer consisting of the first group and the second group and the copolymer consisting of the first group and the third group and then mixing them later. A polymer can be obtained. The mixing ratio of each monomer is not particularly limited, but when the amount of functional groups per unit polymer is increased, the ratio of the monomers selected from the second group and the third group may be increased. good.

The total ion exchange capacity of the fluorine-containing copolymer is not particularly limited, but is preferably 0.5 to 2.0 mg equivalent / g, and more preferably 0.6 to 1.5 mg equivalent / g. Here, the total ion exchange capacity refers to the equivalent number of exchange groups per unit weight of the dry resin, and can be measured by neutralization titration or the like.

In the film body 10 of the ion exchange film 1, a sulfonic acid layer 3 containing a fluorinated polymer having a sulfonic acid group and a carboxylic acid layer 2 containing a fluorinated polymer having a carboxylic acid group are laminated. There is. By forming the membrane body 10 having such a layered structure, the selective permeability of cations such as sodium ions can be further improved.

When the ion exchange film 1 is arranged in the electrolytic cell, the sulfonic acid layer 3 is usually arranged on the anode side of the electrolytic cell, and the carboxylic acid layer 2 is arranged on the cathode side of the electrolytic cell.

The sulfonic acid layer 3 is preferably made of a material having a low electrical resistance, and is preferably thicker than the carboxylic acid layer 2 from the viewpoint of film strength. The film thickness of the sulfonic acid layer 3 is preferably 2 to 25 times that of the carboxylic acid layer 2, and more preferably 3 to 15 times.

The carboxylic acid layer 2 preferably has a high anion exclusion property even if the film thickness is thin. The anion exclusion property referred to here refers to a property of hindering the invasion and permeation of anions into the ion exchange membrane 1. In order to enhance the anion exclusion property, it is effective to arrange a carboxylic acid layer having a small ion exchange capacity with respect to the sulfonic acid layer.

As the fluorine-containing polymer used for the sulfonic acid layer 3, for example, a polymer obtained by using CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F as the monomer of the third group can be used. Suitable.

As the fluorine-containing polymer used for the carboxylic acid layer 2, for example, a polymer obtained by using CF ₂ = CFOCF ₂ CF (CF ₂ ) O (CF ₂ ) ₂ COOCH ₃ as the second group monomer. Is preferable.

(Coating layer)
The ion exchange membrane preferably has a coating layer on at least one surface of the membrane body. Further, as shown in FIG. 7, in the ion exchange membrane 1, coating layers 11a and 11b are formed on both surfaces of the membrane body 10, respectively.
The coating layer contains inorganic particles and a binder.

The average particle size of the inorganic particles is more preferably 0.90 μm or more. When the average particle size of the inorganic particles is 0.90 μm or more, not only gas adhesion but also durability against impurities is extremely improved. That is, by increasing the average particle size of the inorganic particles and satisfying the above-mentioned specific surface area value, a particularly remarkable effect can be obtained. Irregular inorganic particles are preferred in order to satisfy such average particle size and specific surface area. Inorganic particles obtained by melting and inorganic particles obtained by crushing rough stone can be used. Inorganic particles obtained by pulverizing rough stones can be preferably used.

Further, the average particle size of the inorganic particles can be 2 μm or less. When the average particle size of the inorganic particles is 2 μm or less, it is possible to prevent the film from being damaged by the inorganic particles. The average particle size of the inorganic particles is more preferably 0.90 to 1.2 μm.

Here, the average particle size can be measured by a particle size distribution meter (“SALD2200”, Shimadzu Corporation).

The shape of the inorganic particles is preferably an irregular shape. More resistance to impurities. Further, the particle size distribution of the inorganic particles is preferably broad.

The inorganic particles may contain at least one inorganic substance selected from the group consisting of oxides of Group IV elements of the Periodic Table, nitrides of Group IV elements of the Periodic Table, and carbides of Group IV elements of the Periodic Table. preferable. More preferably, it is a zirconium oxide particle from the viewpoint of durability.

The inorganic particles are inorganic particles produced by crushing the rough particles of the inorganic particles, or by melting and purifying the rough stones of the inorganic particles, spherical particles having the same particle diameter are made into an inorganic substance. It is preferably particles.

The rough stone crushing method is not particularly limited, and examples thereof include a ball mill, a bead mill, a colloid mill, a conical mill, a disc mill, an edge mill, a milling mill, a hammer mill, a pellet mill, a VSI mill, a willy mill, a roller mill, and a jet mill. Further, it is preferable to wash after pulverization, and at that time, as a washing method, acid treatment is preferable. Thereby, impurities such as iron adhering to the surface of the inorganic particles can be reduced.

The coating layer preferably contains a binder. The binder is a component that holds inorganic particles on the surface of the ion exchange membrane to form a coating layer. The binder preferably contains a fluorine-containing polymer from the viewpoint of resistance to the electrolytic solution and products produced by electrolysis.

The binder is more likely to be a fluorine-containing polymer having a carboxylic acid group or a sulfonic acid group from the viewpoint of resistance to the electrolytic solution and products produced by electrolysis and adhesion to the surface of the ion exchange membrane. preferable. When a coating layer is provided on a layer (sulfonic acid layer) containing a fluoropolymer having a sulfonic acid group, it is more preferable to use a fluoropolymer having a sulfonic acid group as a binder for the coating layer. .. When a coating layer is provided on a layer (carboxylic acid layer) containing a fluoropolymer having a carboxylic acid group, a fluoropolymer having a carboxylic acid group may be used as a binder for the coating layer. More preferred.

The content of the inorganic particles in the coating layer is preferably 40 to 90% by mass, more preferably 50 to 90% by mass. The content of the binder is preferably 10 to 60% by mass, more preferably 10 to 50% by mass.

The distribution density of the coating layer in the ion exchange membrane is preferably 0.05 to 2 mg per 1 cm ² . When the ion exchange membrane has an uneven shape on the surface, the distribution density of the coating layer is preferably 0.5 to 2 mg per 1 cm ² .

The method for forming the coating layer is not particularly limited, and a known method can be used. For example, a method of applying a coating liquid in which inorganic particles are dispersed in a solution containing a binder by spraying or the like can be mentioned.

(Reinforced core material)
The ion exchange membrane preferably has a reinforced core material arranged inside the membrane body.

The reinforced core material is a member that enhances the strength and dimensional stability of the ion exchange membrane. By arranging the reinforcing core material inside the membrane body, it is possible to control the expansion and contraction of the ion exchange membrane in a desired range. Such an ion exchange membrane does not expand and contract more than necessary during electrolysis and the like, and can maintain excellent dimensional stability for a long period of time.

The structure of the reinforcing core material is not particularly limited, and for example, a yarn called a reinforcing yarn may be spun and formed. The reinforced yarn referred to here is a member constituting the reinforced core material, which can impart desired dimensional stability and mechanical strength to the ion exchange membrane, and can stably exist in the ion exchange membrane. It refers to a thread. By using the reinforced core material obtained by spinning such a reinforced yarn, it is possible to impart more excellent dimensional stability and mechanical strength to the ion exchange membrane.

The material of the reinforced core material and the reinforced yarn used therein is not particularly limited, but is preferably a material having resistance to acids, alkalis, etc., and is required to have long-term heat resistance and chemical resistance, and thus contains fluorine. Fibers made of a system polymer are preferable.

Examples of the fluoropolymer used for the reinforcing core material include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE). , Tetrafluoroethylene-hexafluoropropylene copolymer, trifluorochloroethylene-ethylene copolymer, vinylidene fluoride polymer (PVDF) and the like. Of these, from the viewpoint of heat resistance and chemical resistance, it is preferable to use fibers made of polytetrafluoroethylene.

The yarn diameter of the reinforcing yarn used for the reinforcing core material is not particularly limited, but is preferably 20 to 300 denier, and more preferably 50 to 250 denier. The weaving density (number of threads per unit length) is preferably 5 to 50 threads / inch. The form of the reinforced core material is not particularly limited, and for example, a woven fabric, a non-woven fabric, a knitted fabric, or the like is used, but the form of the woven fabric is preferable. The thickness of the woven fabric is preferably 30 to 250 μm, more preferably 30 to 150 μm.

As the woven fabric or knitted fabric, monofilaments, multifilaments or yarns thereof, slit yarns and the like can be used, and various weaving methods such as plain weave, entwined weave, knitted weave, cord weave and shear sacker can be used.

The weaving method and arrangement of the reinforced core material in the membrane body are not particularly limited, and can be appropriately arranged in consideration of the size and shape of the ion exchange membrane, the desired physical properties of the ion exchange membrane, the usage environment, and the like. ..

For example, the reinforcing core material may be arranged along a predetermined one direction of the membrane body, but from the viewpoint of dimensional stability, the reinforcing core material is arranged along a predetermined first direction, and the first one. It is preferred to place another reinforced core along a second direction that is substantially perpendicular to the direction. Longitudinal direction of the film body By arranging a plurality of reinforcing core materials so as to be substantially orthogonal to each other inside the film body, it is possible to impart more excellent dimensional stability and mechanical strength in multiple directions. For example, it is preferable to weave a reinforcing core material (warp and weft) arranged along the vertical direction and a reinforcing core material (weft) arranged along the horizontal direction on the surface of the membrane body. A plain weave in which warp and weft are alternately raised and lowered and woven, or a entangled weave in which two warps are twisted and woven with a weft, and two or several warp and weft are woven by driving the same number of weft into the warp. It is more preferable to use a slanted weft (Nanakoori) or the like from the viewpoint of dimensional stability, mechanical strength and ease of manufacture.

In particular, it is preferable that the reinforcing core material is arranged along both the MD direction (Machine Direction direction) and the TD direction (Transverse Direction direction) of the ion exchange membrane. That is, it is preferable that the plain weave is performed in the MD direction and the TD direction. Here, the MD direction refers to the direction (flow direction) in which the membrane body and various core materials (for example, reinforced core material, reinforced yarn, sacrificial yarn described later, etc.) are conveyed in the manufacturing process of the ion exchange membrane described later. The TD direction is a direction substantially perpendicular to the MD direction. The yarn woven along the MD direction is called an MD yarn, and the yarn woven along the TD direction is called a TD yarn. Usually, the ion exchange membrane used for electrolysis has a rectangular shape, and the longitudinal direction is often the MD direction and the width direction is often the TD direction. By weaving the reinforced core material which is an MD yarn and the reinforced core material which is a TD yarn, it is possible to impart more excellent dimensional stability and mechanical strength in multiple directions.

The arrangement interval of the reinforcing core material is not particularly limited, and can be appropriately arranged in consideration of the physical characteristics desired for the ion exchange membrane, the usage environment, and the like.

The aperture ratio of the reinforced core material is not particularly limited, and is preferably 30% or more, more preferably 50% or more and 90% or less. The aperture ratio is preferably 30% or more from the viewpoint of the electrochemical properties of the ion exchange membrane, and is preferably 90% or less from the viewpoint of the mechanical strength of the ion exchange membrane.

The aperture ratio of the reinforced core material is the total surface through which substances such as ions (electrolyte solution and cations contained therein (for example, sodium ions)) in the area (A) of the surface of either one of the membrane bodies can pass. It refers to the ratio (B / A) of the area (B). The total surface area (B) through which substances such as ions can pass is the total area of the region of the ion exchange membrane where cations, electrolytic solutions, etc. are not blocked by the reinforcing core material contained in the ion exchange membrane. can.

FIG. 8 is a schematic view for explaining the aperture ratio of the reinforcing core material constituting the ion exchange membrane. FIG. 8 is an enlargement of a part of the ion exchange membrane and shows only the arrangement of the reinforcing core materials 21 and 22 in the region, and the other members are not shown.

A region surrounded by the reinforced core material 21 arranged along the vertical direction and the reinforced core material 22 arranged in the horizontal direction, from the area (A) of the region including the area of the reinforced core material. By subtracting the total area (C) of the above-mentioned region (A), the total area (B) of the region through which a substance such as an ion can pass can be obtained. That is, the aperture ratio can be obtained by the following formula (I).
Aperture ratio = (B) / (A) = ((A)-(C)) / (A) ... (I)

Among the reinforced core materials, a particularly preferable form is a tape yarn containing PTFE or a highly oriented monofilament from the viewpoint of chemical resistance and heat resistance. Specifically, a tape yarn made by slitting a high-strength porous sheet made of PTFE into a tape shape or a highly oriented monofilament made of PTFE using 50 to 300 denier and having a weaving density of 10 to 50 pieces / It is more preferably a plain weave in inches and a reinforced core material having a thickness in the range of 50 to 100 μm. It is more preferable that the aperture ratio of the ion exchange membrane containing the reinforcing core material is 60% or more.

Examples of the shape of the reinforcing thread include a round thread and a tape-shaped thread.

(Communication hole)
The ion exchange membrane preferably has a communication hole inside the membrane body.

The communication hole means a hole that can be a flow path for ions and an electrolytic solution generated during electrolysis. The communication hole is a tubular hole formed inside the membrane body, and is formed by elution of the sacrificial core material (or sacrificial thread) described later. The shape and diameter of the communication hole can be controlled by selecting the shape and diameter of the sacrificial core material (sacrificial thread).

By forming communication holes in the ion exchange membrane, the mobility of the electrolytic solution can be ensured during electrolysis. The shape of the communication hole is not particularly limited, but according to the manufacturing method described later, the shape of the sacrificial core material used for forming the communication hole can be used.

The communication holes are preferably formed so as to alternately pass through the anode side (sulfonic acid layer side) and the cathode side (carboxylic acid layer side) of the reinforced core material. With such a structure, in the portion where the communication hole is formed on the cathode side of the reinforced core material, the ions (for example, sodium ion) transported through the electrolytic solution filled in the communication hole of the reinforced core material become the reinforced core material. It can also flow to the cathode side. As a result, the flow of cations is not blocked, so that the electrical resistance of the ion exchange membrane can be further reduced.

The communication holes may be formed along only one predetermined direction of the membrane body constituting the ion exchange membrane, but from the viewpoint of exhibiting more stable electrolytic performance, the communication holes may be formed in the vertical direction and the horizontal direction of the membrane body. It is preferable that they are formed in both directions.

〔Production method〕
Suitable methods for producing the ion exchange membrane include methods having the following steps (1) to (6).
(1) Step: A step of producing a fluorine-containing polymer having an ion exchange group or an ion exchange group precursor that can become an ion exchange group by hydrolysis.
(2) Step: If necessary, by weaving at least a plurality of reinforced core materials and a sacrificial yarn having a property of dissolving in an acid or an alkali and forming a communication hole, the adjacent reinforced core materials are woven together. The process of obtaining a reinforcing material with sacrificial threads placed between them.
(3) Step: A step of forming a film of the fluoropolymer having an ion exchange group or an ion exchange group precursor that can become an ion exchange group by hydrolysis.
(4) Step: A step of embedding the reinforcing material in the film as needed to obtain a film body in which the reinforcing material is arranged.
(5) Step: A step of hydrolyzing the membrane body obtained in the (4) step (hydrolysis step).
(6) Step: A step (coating step) of providing a coating layer on the film body obtained in the step (5).

Hereinafter, each step will be described in detail.

(1) Step: Step of producing a fluorinated polymer In the step (1), a fluorinated polymer is produced using the raw material monomers described in the first group to the third group. In order to control the ion exchange capacity of the fluorine-containing polymer, the mixing ratio of the raw material monomers may be adjusted in the production of the fluorine-containing polymer forming each layer.

(2) Process: Manufacturing process of reinforcing material The reinforcing material is a woven fabric or the like woven with reinforcing threads. The reinforcing material is embedded in the membrane to form a reinforcing core material. When the ion exchange membrane has communication holes, the sacrificial thread is also woven into the reinforcing material. In this case, the mixed weaving amount of the sacrificial yarn is preferably 10 to 80% by mass, more preferably 30 to 70% by mass of the entire reinforcing material. By weaving the sacrificial thread, it is possible to prevent the reinforced core material from shifting.

The sacrificial yarn has solubility in the membrane manufacturing process or in an electrolytic environment, and rayon, polyethylene terephthalate (PET), cellulose, polyamide and the like are used. Further, polyvinyl alcohol having a thickness of 20 to 50 denier and made of monofilament or multifilament is also preferable.

In the step (2), the aperture ratio, the arrangement of the communication holes, and the like can be controlled by adjusting the arrangement of the reinforcing core material and the sacrificial yarn.

(3) Step: Film formation step In the (3) step, the fluorine-containing polymer obtained in the above step (1) is formed into a film using an extruder. The film may have a single-layer structure, or may have a two-layer structure of a sulfonic acid layer and a carboxylic acid layer, or may have a multi-layer structure of three or more layers, as described above.

Examples of the method of making a film include the following.
A method for separately forming a fluorine-containing polymer having a carboxylic acid group and a fluorine-containing polymer having a sulfonic acid group.
A method of coextruding a fluorine-containing polymer having a carboxylic acid group and a fluorine-containing polymer having a sulfonic acid group to form a composite film.

In addition, a plurality of films may be used for each. Further, co-extruding different kinds of films is preferable because it contributes to increasing the adhesive strength at the interface.

(4) Step: Step of obtaining the film body In the step (4), the reinforcing material obtained in the step (2) is embedded in the film obtained in the step (3) to obtain the film body containing the reinforcing material. obtain.

As a preferable method for forming the film body, (i) a fluoropolymer having a carboxylic acid group precursor (for example, a carboxylic acid ester functional group) located on the cathode side (hereinafter, a layer made of this is referred to as a first layer). And a fluoropolymer having a sulfonic acid group precursor (for example, a sulfonylfluoride functional group) (hereinafter, the layer composed of this is referred to as a second layer) is formed into a film by a coextrusion method, and a heating source and a heating source as necessary. Using a vacuum source, a reinforcing material and a second layer / first layer composite film are laminated in this order on a flat plate or a drum having a large number of pores on the surface via a heat-resistant release paper having air permeability. A method of integrating while removing air between each layer by reducing the pressure at a temperature at which each polymer melts; (ii) Including a sulfonic acid group precursor in addition to the second layer / first layer composite film. A fluoropolymer (third layer) is formed into a film by itself in advance, and if necessary, a heating source and a vacuum source are used to make a flat plate having a large number of pores on the surface or a heat-resistant drum having air permeability. The third layer film, the reinforcing core material, and the composite film consisting of the second layer / first layer are laminated in this order via the release paper, and the air between the layers is removed by reducing the pressure at the temperature at which each polymer melts. However, there is a method of integrating.

Here, coextruding the first layer and the second layer contributes to increasing the adhesive strength at the interface.

Further, the method of integrating under reduced pressure has a feature that the thickness of the third layer on the reinforcing material is larger than that of the pressure pressing method. Further, since the reinforcing material is fixed to the inner surface of the membrane body, it has the ability to sufficiently maintain the mechanical strength of the ion exchange membrane.

The variation of the lamination described here is an example, and a suitable lamination pattern (for example, a combination of each layer) is appropriately selected in consideration of the desired layer structure and physical properties of the film body, and then coextruded. can do.

For the purpose of further enhancing the electrical performance of the ion exchange film, the first layer is composed of a fluoropolymer having both a carboxylic acid group precursor and a sulfonic acid group precursor between the first layer and the second layer. It is also possible to further interpose the four layers, or to use a fourth layer composed of a fluorine-containing polymer having both a carboxylic acid group precursor and a sulfonic acid group precursor instead of the second layer.

The method for forming the fourth layer may be a method in which a fluoropolymer having a carboxylic acid group precursor and a fluoropolymer having a sulfonic acid group precursor are separately produced and then mixed, or the carboxylic acid. A method using a copolymer of a monomer having a group precursor and a monomer having a sulfonic acid group precursor may also be used.

When the fourth layer is composed of an ion exchange membrane, a coextruded film of the first layer and the fourth layer is formed, and the third layer and the second layer are separately formed into a film, as described above. It may be laminated by a method, or the three layers of the first layer / the fourth layer / the second layer may be coextruded into a film at a time.

In this case, the direction in which the extruded film flows is the MD direction. In this way, the membrane body containing the fluorine-containing polymer having an ion exchange group can be formed on the reinforcing material.

Further, it is preferable that the ion exchange membrane has a protruding portion, that is, a convex portion made of a fluorine-containing polymer having a sulfonic acid group on the surface side made of a sulfonic acid layer. The method for forming such a convex portion is not particularly limited, and a known method for forming the convex portion on the resin surface can be adopted. Specifically, for example, a method of embossing the surface of the film body can be mentioned. For example, when the composite film and the reinforcing material are integrated, the convex portion can be formed by using a release paper that has been embossed in advance. When the convex portion is formed by embossing, the height of the convex portion and the arrangement density can be controlled by controlling the embossed shape (shape of the release paper) to be transferred.

(5) Hydrolysis step In the step (5), a step (hydrolysis step) of hydrolyzing the membrane body obtained in the step (4) to convert the ion exchange group precursor into an ion exchange group is performed.

Further, in the step (5), the elution pores can be formed in the membrane body by dissolving and removing the sacrificial yarn contained in the membrane body with an acid or an alkali. The sacrificial yarn may remain in the communication hole without being completely dissolved and removed. Further, the sacrificial yarn remaining in the communication hole may be dissolved and removed by the electrolytic solution when the ion exchange membrane is subjected to electrolysis.

The sacrificial yarn has solubility in an acid or an alkali in the manufacturing process of the ion exchange membrane or in an electrolytic environment, and the elution of the sacrificial yarn forms a communication hole at the site.

The step (5) can be performed by immersing the membrane body obtained in the step (4) in a hydrolysis solution containing an acid or an alkali. As the hydrolysis solution, for example, a mixed solution containing KOH and DMSO (Dimethyl sulfoxide) can be used.

The mixed solution preferably contains 2.5 to 4.0 N of KOH and 25 to 35% by mass of DMSO.

The hydrolysis temperature is preferably 70 to 100 ° C. The higher the temperature, the thicker the apparent thickness can be. More preferably, it is 75 to 100 ° C.

The hydrolysis time is preferably 10 to 120 minutes. The longer the time, the thicker the apparent thickness can be. More preferably, it is 20 to 120 minutes.

Here, a step of forming a communication hole by eluting the sacrificial yarn will be described in more detail. 9 (a) and 9 (b) are schematic views for explaining a method of forming a communication hole of an ion exchange membrane.

9 (a) and 9 (b) show only the communication hole 504 formed by the reinforcing thread 52, the sacrificial thread 504a, and the sacrificial thread 504a, and the other members such as the membrane body are not shown. ing.

First, the reinforcing yarn 52 that constitutes the reinforcing core material in the ion exchange membrane and the sacrificial yarn 504a for forming the communication hole 504 in the ion exchange membrane are used as a crochet reinforcing material. Then, in the step (5), the sacrificial yarn 504a is eluted to form the communication hole 504.

According to the above method, it is convenient because the method of knitting the reinforcing yarn 52 and the sacrificial yarn 504a may be adjusted according to the arrangement of the reinforcing core material and the communication holes in the membrane body of the ion exchange membrane.

FIG. 9A exemplifies a plain weave reinforcing material in which the reinforcing yarn 52 and the sacrificial yarn 504a are woven along both the vertical direction and the horizontal direction on the paper surface. And the arrangement of the sacrificial thread 504a can be changed.

(6) Coating step In the step (6), the coating liquid containing the inorganic particles obtained by crushing the rough stone or melting the rough stone and the binder is prepared, and the coating liquid is applied to the ion exchange membrane obtained in the step (5). A coating layer can be formed by applying and drying on the surface.

As a binder, a fluoropolymer having an ion-exchange group precursor is hydrolyzed with an aqueous solution containing dimethylsulfoxide (DMSO) and potassium hydroxide (KOH), and then immersed in hydrochloric acid to pair the ion-exchange groups. A binder in which ions are replaced with H ⁺ (for example, a fluoropolymer having a carboxyl group or a sulfo group) is preferable. This is preferable because it is easily dissolved in water or ethanol, which will be described later.

This binder is dissolved in a mixed solution of water and ethanol. The volume ratio of water to ethanol is preferably 10: 1 to 1:10, more preferably 5: 1 to 1: 5, and even more preferably 2: 1 to 1: 2. Inorganic particles are dispersed in the solution thus obtained with a ball mill to obtain a coating solution. At this time, the average particle size of the particles can be adjusted by adjusting the time and rotation speed at the time of dispersion. The preferable blending amount of the inorganic particles and the binder is as described above.

The concentration of the inorganic particles and the binder in the coating liquid is not particularly limited, but a thin coating liquid is preferable. As a result, it becomes possible to apply the ion exchange membrane uniformly to the surface.

Further, when dispersing the inorganic particles, a surfactant may be added to the dispersion liquid. As the surfactant, a nonionic surfactant surfactant is preferable, and examples thereof include NOF Corporation HS-210, NS-210, P-210, E-212 and the like.

An ion exchange membrane can be obtained by applying the obtained coating liquid to the surface of the ion exchange membrane by spray coating or roll coating.

[Microporous membrane]
As described above, the microporous membrane of the present embodiment is not particularly limited as long as it can be a laminated body with an electrode for electrolysis, and various microporous membranes can be applied.
The porosity of the microporous membrane of this embodiment is not particularly limited, but can be, for example, 20 to 90, preferably 30 to 85. The porosity can be calculated, for example, by the following formula.
Porosity = (1- (weight of membrane in dry state) / (volume calculated from thickness, width, length of membrane and weight calculated from density of membrane material)) x 100
The average pore size of the microporous membrane of the present embodiment is not particularly limited, but can be, for example, 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm. For the average pore diameter, for example, the film is cut perpendicularly in the thickness direction, and the cut surface is observed by FE-SEM. It can be obtained by measuring the diameters of the observed holes at about 100 points and averaging them.
The thickness of the microporous membrane of the present embodiment is not particularly limited, but can be, for example, 10 μm to 1000 μm, preferably 50 μm to 600 μm. The thickness can be measured using, for example, a micrometer (manufactured by Mitutoyo Co., Ltd.) or the like.
Specific examples of the microporous membrane as described above include Agfa's Zirfon Perl UTP 500 (also referred to as Zirfon membrane in the present embodiment), International Publication No. 2013-183584, International Publication No. 2016-203701. And so on.

In the present embodiment, it is preferable that the diaphragm includes a first ion exchange resin layer and a second ion exchange resin layer having an EW (ion exchange equivalent) different from that of the first ion exchange resin layer. .. Further, it is preferable that the diaphragm contains a first ion exchange resin layer and a second ion exchange resin layer having a functional group different from that of the first ion exchange resin layer. The ion exchange equivalent can be adjusted by the functional group to be introduced, and the functional groups to be introduced are as described above.

(Water electrolysis)
The electrolytic cell in the present embodiment, which is used for water electrolysis, has a configuration in which the ion exchange film in the electrolytic cell for performing salt electrolysis described above is changed to a microporous film. Further, it is different from the above-mentioned electrolytic cell in the case of performing salt electrolysis in that the raw material to be supplied is water. As for other configurations, the electrolytic cell for water electrolysis can adopt the same configuration as the electrolytic cell for salt electrolysis. In the case of salt electrolysis, chlorine gas is generated in the anode chamber, so titanium is used as the material of the anode chamber, but in the case of water electrolysis, oxygen gas is only generated in the anode chamber, so the cathode chamber. You can use the same material as. For example, nickel and the like can be mentioned. Further, as the anode coating, a catalyst coating for oxygen generation is suitable. Examples of catalyst coatings include platinum group metals and transition gold group metals, oxides, hydroxides and the like. For example, elements such as platinum, iridium, palladium, ruthenium, nickel, cobalt and iron can be used.

The present embodiment will be described in more detail with reference to the following examples and comparative examples, but the present embodiment is not limited to the following examples.

As the diaphragm, an ion exchange membrane b manufactured as described below was used.
As the reinforcing core material, a monofilament made of polytetrafluoroethylene (PTFE) and 90 denier was used (hereinafter referred to as PTFE yarn). As a sacrificial yarn, a yarn obtained by twisting 35 denier, 6-filament polyethylene terephthalate (PET) 200 times / m was used (hereinafter referred to as PET yarn). First, a woven fabric was obtained by plain weaving so that 24 PTFE yarns / inch and two sacrificial yarns were arranged between adjacent PTFE yarns in both the TD and MD directions. The obtained woven fabric was crimped with a roll to obtain a woven fabric having a thickness of 70 μm.
Next, the dry resin resins A and CF, which are copolymers of CF ₂ = CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ COOCH ₃ and have an ion exchange capacity of 0.85 mg equivalent / g. A dry resin resin B having an ion exchange capacity of 1.03 mg equivalent / g was prepared as a copolymer of ₂ = CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F.
Using these resins A and B, a two-layer film X having a thickness of the resin A layer of 15 μm and a thickness of the resin B layer of 104 μm was obtained by a coextrusion T-die method.
Subsequently, a release paper (conical embossing with a height of 50 μm), a reinforcing material, and a film X are laminated in this order on a hot plate having a heating source and a vacuum source inside and having micropores on the surface thereof. A composite film was obtained by heating and reducing the pressure for 2 minutes under the conditions of a hot plate surface temperature of 223 ° C. and a vacuum degree of 0.067 MPa, and then removing the release paper.
The obtained composite membrane was saponified by immersing it in an aqueous solution at 80 ° C. containing 30% by mass of dimethyl sulfoxide (DMSO) and 15% by mass of potassium hydroxide (KOH) for 20 minutes. Then, it was immersed in an aqueous solution containing 0.5 N of sodium hydroxide (NaOH) at 50 ° C. for 1 hour to replace the counterion of the ion exchange group with Na, and then washed with water. It was further dried at 60 ° C.
Further, 20% by mass of zirconium oxide having a primary particle size of 1 μm was added to a 5% by mass ethanol solution of the acid type resin of the resin B to prepare a dispersed suspension, and the above-mentioned composite was prepared by a suspension spray method. A coating of zirconium oxide was formed on the surface of the composite membrane by spraying on both sides of the membrane to obtain an ion exchange membrane A. The coating density of zirconium oxide was measured by fluorescent X-ray measurement and found to be 0.5 mg / cm ² . Here, the average particle size was measured by a particle size distribution meter (“SALD (registered trademark) 2200” manufactured by Shimadzu Corporation).

The following cathodes and anodes were used as electrodes.
As an electrode base material for cathode electrolysis, an electrolytic nickel foil having a gauge thickness of 22 μm was prepared. One side of this nickel foil was roughened by electrolytic nickel plating. The arithmetic average roughness Ra of the roughened surface was 0.95 μm. The surface roughness was measured under the same conditions as the surface roughness measurement of the blasted nickel plate.
A circular hole was punched in this nickel foil by punching to make a porous foil. The opening rate was 44%.
A coating liquid for forming an electrode catalyst was prepared by the following procedure. A ruthenium nitrate solution (Furuya Metal Co., Ltd.) and cerium nitrate (Kishida Chemical Co., Ltd.) having a ruthenium concentration of 100 g / L were mixed so that the molar ratio of ruthenium element and cerium element was 1: 0.25. This mixture was sufficiently stirred and used as a cathode coating solution.
A vat containing the above coating liquid was installed at the bottom of the roll coating device. A coating roll made of PVC (polyvinyl chloride) wrapped with closed cell type foamed EPDM (ethylene, propylene, diene rubber) rubber (Inoac Corporation, E-4088, thickness 10 mm) is always in contact with the coating liquid. Installed in. A coating roll around which the same EPDM was wound was installed on the upper part, and a PVC roller was installed on the coating roll. The electrode substrate was passed between the second coating roll and the uppermost PVC roller to coat the coating liquid (roll coating method). Then, drying at 50 ° C. for 10 minutes, calcination at 150 ° C. for 3 minutes, and firing at 350 ° C. for 10 minutes were carried out. A series of operations of coating, drying, temporary firing, and firing were repeated until a predetermined coating amount was reached. The thickness of the prepared electrode was 29 μm. The thickness of the catalyst layer containing ruthenium oxide and cerium oxide was 7 μm, which was obtained by subtracting the thickness of the electrode base material for electrolysis from the thickness of the electrode. The coating was also formed on the unroughened surface.

As the electrode base material for anode electrolysis, a titanium non-woven fabric having a gauge thickness of 100 μm, a titanium fiber diameter of about 20 μm, a basis weight of 100 g / m ² , and a pore size of 78% was used.
A coating liquid for forming an electrode catalyst was prepared by the following procedure. Ruthenium chloride solution with ruthenium concentration of 100 g / L (Tanaka Kikinzoku Kogyo Co., Ltd.), iridium chloride with iridium concentration of 100 g / L (Tanaka Kikinzoku Kogyo Co., Ltd.), titanium tetrachloride (Wako Pure Chemical Industries, Ltd.), ruthenium element And the ruthenium element and the titanium element were mixed so as to have a molar ratio of 0.25: 0.25: 0.5. This mixture was sufficiently stirred and used as an anode coating solution.
A vat containing the above coating liquid was installed at the bottom of the roll coating device. A coating roll made of PVC (polyvinyl chloride) wrapped with closed cell type foamed EPDM (ethylene, propylene, diene rubber) rubber (Inoac Corporation, E-4088, thickness 10 mm) is always in contact with the coating liquid. Installed in. A coating roll around which the same EPDM was wound was installed on the upper part, and a PVC roller was installed on the coating roll. The electrode substrate was passed between the second coating roll and the uppermost PVC roller to coat the coating liquid (roll coating method). After applying the above coating liquid to the titanium porous foil, it was dried at 60 ° C. for 10 minutes and fired at 475 ° C. for 10 minutes. After repeating the series of operations of coating, drying, temporary firing, and firing, firing was performed at 520 ° C. for 1 hour.

[Example 1]
(Example using a cathode-membrane laminate)
A wound body was prepared in advance as follows. First, an ion exchange membrane b having a length of 1.5 m and a width of 2.5 m was prepared by the method described above. Further, four cathodes having a length of 0.3 m and a width of 2.4 m were prepared by the method described above.
After immersing the ion exchange membrane b in a 2% baking soda solution for a whole day and night, the cathodes were arranged without gaps on the carboxylic acid layer side to prepare a laminate of the cathode and the ion exchange membrane b. When the cathode was placed on the membrane, the interfacial tension acted upon contact with the aqueous solution of baking soda, and the cathode and the membrane became one so as to stick to each other. No pressure was applied to this integration. The temperature at the time of integration was 23 ° C. This laminated body was wound around a polyvinyl chloride (PVC) pipe having an outer diameter of 76 mm and a length of 1.7 m to prepare a wound body. The temperature of 200 ° C. or higher was required to melt the ion exchange membrane b, and the ion exchange membrane did not melt when integrated in this embodiment.
Next, in the existing large electrolytic cell (electrolytic cell having the same structure as that shown in FIGS. 3 and 4), the fixed state of the adjacent electrolytic cell and ion exchange membrane by the press is released, and the existing diaphragm is taken out. There was a gap between the electrolytic cells. Then, the wound body was carried onto a large electrolytic cell. On the large electrolytic cell, the wound state was released so as to pull out the wound laminate from the state where the PVC pipe was erected. At this time, the laminate was maintained almost perpendicular to the ground, but the cathode did not come off. Next, after inserting the laminated body between the electrolytic cells, the electrolytic cells were moved and sandwiched between the electrolytic cells.
The electrodes and diaphragm could be replaced more easily than in the past. It was evaluated that electrode renewal and diaphragm replacement could be completed in about several tens of minutes per cell.

[Example 2]
(Example using an anode-membrane laminate)
A wound body was prepared in advance as follows. First, an ion exchange membrane b having a length of 1.5 m and a width of 2.5 m was prepared by the method described above. Further, four anodes having a length of 0.3 m and a width of 2.4 m were prepared by the method described above.
After immersing the ion exchange membrane b in a 2% baking soda solution for a whole day and night, the anodes were arranged on the sulfonic acid layer side without any gaps to prepare a laminate of the anode and the ion exchange membrane. When the anode was placed on the membrane, the interfacial tension acted on the contact with the aqueous solution of baking soda, and the anode and the membrane were integrated so as to be attracted. No pressure was applied when the anode and the membrane were integrated in this way. The temperature at the time of integration was 23 ° C. This laminated body was wound around a polyvinyl chloride (PVC) pipe having an outer diameter of 76 mm and a length of 1.7 m to prepare a wound body.
Next, in the existing large electrolytic cell (the same electrolytic cell as in Example 1), the fixed state of the adjacent electrolytic cell and the ion exchange membrane by the press is released, the existing diaphragm is taken out, and there is a gap between the electrolytic cells. I made it. Then, the wound body was carried onto a large electrolytic cell. On the large electrolytic cell, the wound state was released so as to pull out the wound laminate from the state where the PVC pipe was erected. At this time, the laminate was maintained almost perpendicular to the ground, but the anode did not come off. Next, after inserting the laminated body between the electrolytic cells, the electrolytic cells were moved and sandwiched between the electrolytic cells.
The electrodes and diaphragm could be replaced more easily than in the past. It was evaluated that electrode renewal and diaphragm replacement could be completed in about several tens of minutes per cell.

[Example 3]
(Example using an anode / cathode-membrane laminate)
A wound body was prepared in advance as follows. First, an ion exchange membrane b having a length of 1.5 m and a width of 2.5 m was prepared by the method described above. In addition, four anodes and four anodes each having a length of 0.3 m and a width of 2.4 m were prepared by the method described above.
After immersing the ion exchange membrane b in a 2% sodium bicarbonate solution for a whole day and night, the cathode was arranged on the carboxylic acid layer side and the anode was arranged on the sulfonic acid layer side without any gaps to prepare a laminate of the cathode, the anode and the ion exchange membrane b. When the cathode and anode were placed on the membrane, the interfacial tension acted upon contact with the aqueous solution of baking soda, and the cathode, anode and membrane were integrated so as to stick to each other. No pressure was applied to this integration. The temperature at the time of integration was 23 ° C. This laminated body was wound around a polyvinyl chloride (PVC) pipe having an outer diameter of 76 mm and a length of 1.7 m to prepare a wound body.
Next, in the existing large electrolytic cell (the same electrolytic cell as in Example 1), the fixed state of the adjacent electrolytic cell and the ion exchange membrane by the press is released, the existing diaphragm is taken out, and there is a gap between the electrolytic cells. I made it. Then, the wound body was carried onto a large electrolytic cell. On the large electrolytic cell, the wound state was released so as to pull out the wound laminate from the state where the PVC pipe was erected. At this time, the laminate was maintained almost perpendicular to the ground, but the anode did not come off. Next, after inserting the laminated body between the electrolytic cells, the electrolytic cells were moved and sandwiched between the electrolytic cells.
The electrodes and diaphragm could be replaced more easily than in the past. It was evaluated that electrode renewal and diaphragm replacement could be completed in about several tens of minutes per cell.

[Comparative Example 1]
As described below, a membrane electrode laminate in which the electrodes were thermocompression bonded to the diaphragm was prepared with reference to the examples of JP-A-58-48686.
Nickel expanded metal having a gauge thickness of 100 μm and a pore size of 33% was used as the electrode base material for cathode electrolysis, and electrode coating was performed in the same manner as in Example 1. The size of the electrodes was 200 mm × 200 mm, and the number of electrodes was 72. Then, one side of the electrode was subjected to the inactivation treatment according to the following procedure. A polyimide adhesive tape (Chukoh Chemical Industries, Ltd.) is attached to one side of the electrode, PTFE dispersion (Mitsui DuPont Fluorochemical Co., Ltd., 31-JR (trade name)) is applied to the other side, and dried in a muffle furnace at 120 ° C for 10 minutes. The polyimide tape was peeled off, and the sintering treatment was carried out in a muffle furnace set at 380 ° C. for 10 minutes. This operation was repeated twice to inactivate one side of the electrode.
A film formed by two layers of a perfluorocarbon polymer (C polymer) having a terminal functional group of "-COOCH ₃ " and a perfluorocarbon polymer (S polymer) having a terminal group of "-SO ₂ F" was produced. The thickness of the C polymer layer was 3 mils, and the thickness of the S polymer layer was 4 mils. The two-layer membrane was saponified, and the terminal of the polymer was hydrolyzed to introduce an ion exchange group. The C polymer terminal was hydrolyzed to a carboxylic acid group, and the S polymer terminal was hydrolyzed to a sulfo group. The ion exchange capacity as a sulfonic acid group was 1.0 meq / g, and the ion exchange capacity as a carboxylic acid group was 0.9 meq / g. The size of the obtained ion exchange membrane was the same as that of Example 1.
A hot press (thermocompression bonding) was performed with the inactivated electrode surface of the electrode facing the surface having a carboxylic acid group as an ion exchange group to integrate the ion exchange membrane and the electrode. That is, at a temperature at which the ion exchange membrane melts, 72 electrodes of 200 mm square were integrated with one ion exchange membrane having a length of 1500 mm and a width of 2500 mm. Even after thermocompression bonding, one side of the electrode was exposed, and there was no part where the electrode penetrated the film.
In the large size of 1500 mm × 2500 mm, the process of integrating the ion exchange membrane and the electrode by thermocompression bonding required more than one day. That is, it was evaluated that it took more time in Comparative Example 1 to renew the electrodes and replace the diaphragm than in Examples.

Explanation of reference numerals for FIGS. 1 to 5 1 ... Electrolytic cell, 2 ... Ion exchange film, 4 ... Electrolytic cell, 5 ... Press, 6 ... Cathode terminal, 7 ... Anodic terminal 10, ... Electrolytic cell, 11 ... Anosome, 12 ... Anodic gasket, 13 ... Cathode gasket, 18 ... Reverse current absorber, 18a ... Base material, 18b ... Reverse current Absorption layer, 19 ... bottom of anode chamber, 20 ... cathode chamber, 21 ... cathode, 22 ... metal elastic body, 23 ... current collector, 24 ... support, 30 ... .. partition wall, 40 ... Cathode structure for electrolysis.

Explanation of reference numerals with respect to FIG. 10 ... Electrode electrode base material for electrolysis, 20 ... First layer, 30 ... Second layer, 100 ... Electrode for electrolysis.

Explanation of reference numerals for FIGS. 7 to 9 1 ... ion exchange membrane, 2 ... carboxylic acid layer, 3 ... sulfonic acid layer, 4 ... reinforced core material, 10 ... film body, 11a, 11b ... coating layer, 21,22 ... reinforced core Material, 100 ... Electrolytic cell, 200 ... Anode, 300 ... Cathode, 52 ... Reinforcing thread, 504a ... Sacrificial thread, 504 ... Communication hole.

Claims (2)

For manufacturing a new electrolytic cell by arranging a laminate in an existing electrolytic cell provided with an anode, a cathode facing the anode, and a diaphragm arranged between the anode and the cathode. It ’s a method,
The step (A) of obtaining the laminate by integrating the electrode for electrolysis and the new diaphragm at a temperature at which the diaphragm does not melt.
After the step (A), the step (B) of exchanging the diaphragm in the existing electrolytic cell with the laminated body,
Have,
The electrode for electrolysis functions as an anode or a cathode, and is separate from the anode and the cathode in the existing electrolytic cell.
A method for manufacturing an electrolytic cell , wherein the integration is performed by an interfacial tension between the electrolytic electrode and the new diaphragm . The method for manufacturing an electrolytic cell according to claim 1, wherein the integration is performed under normal pressure.

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