JP7104533B2 - Laminate - Google Patents

Description

The present invention relates to a laminate.

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 provided with a diaphragm, more specifically, an ion exchange membrane or a microporous membrane 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 with a diaphragm interposed between the electrolytic cells. 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 (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 diaphragm can be easily renewed by removing it from between the electrolytic cells and inserting a new diaphragm. 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 electrolysis factory, and returning to an electrolysis tank occurs. 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, salt concentration 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. Therefore, it cannot be used practically.
The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to improve the work efficiency at the time of electrode renewal in the electrolytic cell, and further, to exhibit excellent electrolysis performance even after the renewal. It is an object of the present invention to provide a laminate capable of producing.

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved by a laminate in which the diaphragm and the electrode for electrolysis are partially fixed, and complete the present invention. It came to.
That is, the present invention includes the following aspects.
[1]
With the diaphragm,
An electrode for electrolysis fixed to at least one region on the surface of the diaphragm,
Have,
A laminate in which the proportion of the region on the surface of the diaphragm is greater than 0% and less than 93%.
[2]
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, From Re, Os, Al, In, Sn, Sb, Ga, Ge, B, C, N, O, Si, P, S, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb and Dy The laminate according to [1], which contains at least one catalyst component selected from the group.
[3]
The laminate according to [1] or [2], wherein at least a part of the electrode for electrolysis is fixed through the diaphragm in the region.
[4]
The laminate according to any one of [1] to [3], wherein at least a part of the electrode for electrolysis is located and fixed inside the diaphragm in the region.
[5]
The laminate according to any one of [1] to [4], further comprising a fixing member for fixing the diaphragm and the electrode for electrolysis.
[6]
The laminate according to [5], wherein at least a part of the fixing member grips the diaphragm and the electrode for electrolysis from the outside.
[7]
The laminate according to [5] or [6], wherein at least a part of the fixing member magnetically fixes the diaphragm and the electrode for electrolysis.
[8]
The diaphragm contains an ion exchange membrane containing an organic resin in the surface layer.
The laminate according to any one of [1] to [7], wherein the organic resin is present in the region.
[9]
Any one of [1] to [8], wherein the diaphragm includes a first ion exchange resin layer and a second ion exchange resin layer having an EW different from that of the first ion exchange resin layer. The laminate described in.
[10]
Any one of [1] to [8], wherein the diaphragm includes 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 laminate according to the section.

According to the laminate of the present invention, it is possible to improve the work efficiency at the time of electrode renewal in the electrolytic cell, and further, it is possible to exhibit excellent electrolysis performance even after the renewal.

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 the schematic 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. FIG. 5A is a schematic cross-sectional view of a laminated body illustrating an embodiment in which at least a part of an electrode for electrolysis is fixed through a diaphragm. FIG. 5B is an explanatory diagram showing a process for obtaining the structure of FIG. 5A. FIG. 6A is a schematic cross-sectional view of a laminated body illustrating an embodiment in which at least a part of an electrode for electrolysis is located and fixed inside a diaphragm. FIG. 6B is an explanatory diagram showing a process for obtaining the structure of FIG. 6A. 7A to 7C are schematic cross-sectional views of a laminated body illustrating an embodiment in which a thread-like fixing member is used as a fixing member for fixing the diaphragm and the electrode for electrolysis. It is a schematic cross-sectional view of the laminated body which illustrates the aspect of fixing using an organic resin as a fixing member for fixing a diaphragm and an electrode for electrolysis. FIG. 9A is a schematic cross-sectional view of a laminated body illustrating a mode in which at least a part of the fixing member grips and fixes the diaphragm and the electrode for electrolysis from the outside. FIG. 9B is a schematic cross-sectional view of a laminated body illustrating a mode in which at least a part of the fixing member fixes the diaphragm and the electrode for electrolysis by a magnetic force. It is a schematic cross-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 explanatory drawing which shows the laminated body in Example 1. FIG. It is explanatory drawing which shows the laminated body in Example 2. FIG. It is explanatory drawing which shows the laminated body in Example 3. FIG. It is explanatory drawing which shows the laminated body in Example 4. FIG. It is explanatory drawing which shows the laminated body in Example 5. It is explanatory drawing which shows the laminated body in Example 6.

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 the embodiment, and the embodiment is not construed as being limited to this. The present invention can be appropriately modified and implemented 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 ratios of the drawings are not limited to those shown.

[Laminated body]
The laminate of the present embodiment has a diaphragm and an electrode for electrolysis fixed to at least one region (hereinafter, also simply referred to as “fixed region”) of the surface of the diaphragm, and is located on the surface of the diaphragm. , The proportion of the region is more than 0% and less than 93%. Since it is configured in this way, the laminate of the present embodiment can improve the work efficiency at the time of electrode renewal in the electrolytic cell, and can further exhibit excellent electrolysis performance even after the renewal.
That is, according to the laminate of the present embodiment, when the electrode is renewed, the electrode is renewed by a simple operation similar to the renewal of the diaphragm without complicated work such as peeling off the existing electrode fixed to the electrolytic cell. Therefore, work efficiency is greatly improved.
Further, according to the laminated body of the present embodiment, the electrolytic performance of the existing electrolytic cell can be maintained or improved at the same level as the performance at the time of a new product. Therefore, the electrodes fixed to the existing electrolytic cell and functioning as the anode and the cathode need only function as the feeder, and the catalyst coating can be significantly reduced or reduced to zero. The feeding body referred to here means a deteriorated electrode (that is, an existing electrode), an electrode that is not coated with a catalyst, or the like.

[Electrode for electrolysis]
The electrode for electrolysis in the present embodiment is not particularly limited as long as it is an electrode used for electrolysis, but the area of the surface of the electrode for electrolysis facing the diaphragm (corresponding to the area S2 of the energizing surface described later) is 0. It is preferably 01 m ² or more. The “surface facing the diaphragm” means the surface of the surface of the electrode for electrolysis on the side where the diaphragm is present. That is, the surface of the electrode for electrolysis facing the diaphragm can be said to be a surface in contact with the surface of the diaphragm. When the area of the surface of the electrode for electrolysis facing the diaphragm is 0.01 m ² or more, sufficient productivity can be ensured, and in particular, sufficient productivity tends to be obtained for performing industrial electrolysis. be. As described above, from the viewpoint of ensuring sufficient productivity and practicality as a laminate used for renewal of the electrolytic cell, the area of the facing surface of the electrode for electrolysis with the diaphragm is 0.1 m ² or more. More preferably, 1 m ² or more is further preferable. Such an area can be measured, for example, by the method described in Examples.

The electrode for electrolysis in the present embodiment has good handleability and has good adhesion to a diaphragm such as an ion exchange membrane or a microporous membrane, 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, further preferably 20 mg / cm ² or less, and further, handleability and adhesiveness. From a comprehensive viewpoint that combines economic efficiency, it is 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.

Such a force can be measured by the following method (i) or (ii), and is obtained by the value obtained by the measurement of the method (i) (also referred to as "applied force (1)") and the measurement of the method (ii). The given value (also referred to as "applied force (2)") may be the same or different, but any value shall be less than 1.5 N / mg · cm ² . Is preferable.

[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. The ion exchange membrane (170 mm square) and the electrode sample (130 mm square) are laminated in this order, and after the laminate is sufficiently immersed in pure water, excess water adhering to the surface of the laminate is removed. Obtain a sample for measurement. The arithmetic mean 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 in the vertical direction at 10 mm / min using a tensile compression tester to obtain an electrode sample. The weight when the temperature is raised by 10 mm in the vertical direction is measured. 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 ion exchange membrane and the mass of the electrode sample of the portion overlapping the ion exchange membrane, the applied force per unit mass / unit area (1) (N) / Mg · cm ² ) is calculated.

The applied force (1) 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 ), even 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 sample for measurement. 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 in the vertical direction at 10 mm / min using a tensile compression tester to obtain an electrode sample. , Measure the weight when it rises 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 adhesive force per unit mass / unit area (2) (N / mg)・ Calculate cm ² ).

The applied force (2) per unit mass / unit area obtained by the method (ii) 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 ), even 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 is not 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.

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 (body). 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 is placed on the curved surface of a polyethylene pipe (outer diameter 280 mm) so that the electrode sample in the laminate is on the outside. And the pipe are 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 film (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 is placed on a curved surface of a polyethylene pipe (outer diameter 145 mm) so that the electrode sample in the laminate is on the outside. And the pipe are 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 film (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 pore size or void ratio 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 portion is also considered to the submicron order or only the visible opening is considered. In the present embodiment, the volume V is calculated from the values of the gauge thickness, width, and length of the electrode, and the weight W is actually measured to calculate the pore opening ratio A by the following formula.
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 pore size can be adjusted by changing the area where the metal is punched per unit area for punching metal, changing the SW (minor diameter), LW (major diameter), and feed values for expanded metal. 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. Change the mold to make

Hereinafter, one embodiment of the electrode for electrolysis in this 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. 1, 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 easier 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. 1, 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 electrode base material 10 for electrolysis is not particularly limited, but for example, a valve metal typified by nickel, nickel alloy, stainless steel, titanium or 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 base material containing nickel (Ni) is preferable.
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 intended purpose. As the shape, any of punching metal, non-woven metal, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting 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 in which a pattern is formed on a substrate with a photoresist, and a portion not protected by the resist is electroplated 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 non-woven fabric, expanded metal, punching metal, perforated metal foil and the like can be used.
Examples of the electrode base material 10 for electrolysis include perforated metal foil, wire mesh, metal non-woven fabric, punching metal, expanded metal, and foamed metal.
As the plate material before being processed into punching metal and expanded metal, a rolled plate material, an electrolytic foil and the like are 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 one side or both sides uneven.
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. 1, 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, ruthenium oxide and titanium oxide, titanium oxidation contained in the first layer 20 is compared with 1 mol of 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 amount of iridium oxide is preferably 0.2 to 3 mol, more preferably 0.3 to 2.5 mol. Further, the amount of 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 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 an 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, etc., 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. As a result, the chlorine overvoltage immediately after electrolysis can be further reduced.

The second layer 30 preferably contains palladium oxide, a solid solution of palladium oxide and platinum, or an alloy of palladium and platinum. As a result, the chlorine overvoltage immediately after electrolysis can be further reduced.

The thicker the second layer 30, the longer the period during which the electrolytic performance can be maintained, but from the viewpoint of economy, 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 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 a 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, if necessary, it is preferable to contain an oxide or a hydroxide of a lanthanoid element as the second component. 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 electrode 100 for electrolysis exhibits better durability and the electrolysis voltage can be reduced.
Examples of preferred combinations are ruthenium only, ruthenium + nickel, ruthenium + cerium, ruthenium + lantern, ruthenium + lanthanum + platinum, ruthenium + lanthanum + palladium, ruthenium + placeodium, ruthenium + placeodium + platinum, ruthenium + placeodium + platinum + Palladium, ruthenium + neodymium, ruthenium + neodymium + platinum, ruthenium + neodymium + manganese, ruthenium + neodymium + iron, ruthenium + neodymium + cobalt, ruthenium + neodymium + zinc, ruthenium + neodymium + gallium, ruthenium + neodymium + sulfur, ruthenium + Neodim + 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 + lantern + cerium, platinum + iridium, platinum + palladium, platinum + iridium + palladium, Examples include platinum + nickel + palladium, platinum + nickel + ruthenium, platinum-nickel alloy, platinum-cobalt alloy, platinum-iron alloy, 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, the main component of the catalyst is preferably 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, a nickel oxide, a platinum group metal, a platinum group metal oxide, and a platinum group metal hydroxide are preferable. The intermediate layer can be formed by applying and firing a solution containing the components forming the intermediate layer, or the base material is heat-treated at a temperature of 300 to 600 ° C. in an air atmosphere 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 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 of 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. If it is 20 μm or less, a strong catalyst layer can be formed with little loss from the base material. 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 even more preferable. If it is 135 μm or less, good handleability can be obtained. Further, from the same viewpoint as described 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 electrolysis performance, the electrolysis 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 adhesive force with 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 described 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. .. 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 electrode 100 for electrolysis will be described in detail.
In the present embodiment, the first layer 20, preferably the second layer, is placed on the electrode base material 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 base material 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, etc., 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 solution) 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 contents of ruthenium, iridium and titanium in the first coating liquid are substantially the same as those in the first layer 20.

The metal salt may be in any form of chloride salt, nitrate, sulfate, metal alkoxide, and the like. The solvent of the first coating liquid can be selected according to the type of 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 to 350 ° C., if necessary, between drying and thermal decomposition. The drying, pre-baking and thermal decomposition temperatures can be appropriately selected depending on the composition of the first coating liquid and the solvent type. The time for each thermal decomposition is preferably long, but from the viewpoint of electrode productivity, 3 to 60 minutes is preferable, and 5 to 20 minutes is more preferable.

The coating (first layer 20) is formed to a predetermined thickness by repeating the above cycle of coating, drying and thermal decomposition. 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) on 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 metal content in the first coating liquid is substantially equal to that of the first layer 20.

The metal salt may be in any form of chloride salt, nitrate, sulfate, metal alkoxide, and the like. The solvent of the first coating liquid can be selected according to the type of 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 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 to 350 ° C., if necessary, between drying and thermal decomposition. The drying, pre-baking and thermal decomposition temperatures can be appropriately selected depending on the composition of the first coating liquid and the solvent type. The time for each thermal decomposition is preferably long, but from the viewpoint of electrode productivity, 3 to 60 minutes is preferable, and 5 to 20 minutes is more preferable.

The coating (first layer 20) is formed to a predetermined thickness by repeating the above cycle of coating, drying and thermal decomposition. 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 liquid) on 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 base material simply by heating the base material 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 base material in a chamber and irradiating a metal 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 a 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 base material 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.

The electrode for electrolysis in this embodiment can be used integrally with a diaphragm such as an ion exchange membrane or a microporous membrane. Therefore, the laminate of the present embodiment can be used as a membrane-integrated electrode, and the work of replacing the cathode and the anode when renewing the electrodes becomes unnecessary, and the work efficiency is greatly improved.
Further, according to the electrode integrated with the diaphragm such as an ion exchange membrane or a microporous membrane, the electrolytic performance can be equal to or improved from the performance at the time of a new product.

Hereinafter, the ion exchange membrane 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 the electrode for electrolysis, and various ion exchange membranes can be applied. In the present embodiment, an ion exchange membrane having a membrane body containing a hydrocarbon-based polymer or a fluorine-containing polymer having an ion-exchange group 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. An 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 includes either a layer or 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. 2 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 polymer having an ion exchange group or a fluorine-containing polymer, 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 preferably 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.

(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 polymer having an ion exchange group or a fluorine-containing polymer, 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 polymer 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 composed of fluorinated hydrocarbons, 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 melt-processed. A polymer (hereinafter, sometimes referred to as "fluorine-containing polymer (a)") is used to prepare a precursor of the membrane body 10, and then the ion exchange group precursor is converted into an ion exchange group to form a film. The main body 10 can be obtained.

The fluorine-containing polymer (a) contains, for example, at least one monomer selected from the first group below and at least one monomer selected from the second group below and / or the third group below. It can be produced by copolymerizing. It can also be produced by homopolymerization of one type of monomer selected from any of the following first group, the following second group, and the following third 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 alkali 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 represents 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 alkali 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 they are lost from coalescence.

Among the above, the monomers represented by the following 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 sulfone-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 ₂ F 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 copolymers 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 kind of monomer may be selected from the monomers of the first group and the third group and copolymerized. Further, in the case of a fluorine-containing polymer having a carboxylic acid group and a sulfonic acid group, at least one kind of monomer is selected from each of the first group, second group and third group monomers and co-produced. 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 increasing the amount of functional groups per unit polymer, the ratio of the monomers selected from the second group and the third group can 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 amount of the exchange group 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 fluorine-containing polymer having a sulfonic acid group and a carboxylic acid layer 2 containing a fluorine-containing 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 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 that tends to prevent 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. 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 monomer of the second group. 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. 2, 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 preferable in order to satisfy such average particle size and specific surface area. Inorganic particles obtained by melting and inorganic particles obtained by crushing rough stones can be used. Preferably, the inorganic particles obtained by pulverizing the rough stone 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. A binder is a component that holds inorganic particles on the surface of an 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 products obtained by electrolytic solution and electrolysis and adhesion to the surface of the ion exchange film. preferable. When a coating layer is provided on a layer containing a fluorinated polymer having a sulfonic acid group (sulfonic acid layer), it is more preferable to use a fluorinated polymer having a sulfonic acid group as a binder for the coating layer. .. When a coating layer is provided on a layer containing a fluorinated polymer having a carboxylic acid group (carboxylic acid layer), a fluorinated polymer 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 reinforcing yarn referred to here is a member constituting the reinforcing 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 a reinforced core material obtained by spinning such a reinforcing yarn, it is possible to impart more excellent dimensional stability and mechanical strength to the ion exchange membrane.

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

Examples of the fluorine-containing polymer 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 lines / 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 reinforced core material may be arranged along a predetermined one direction of the membrane body, but from the viewpoint of dimensional stability, the reinforced 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 reinforced 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 film body. A plain weave in which warps and wefts 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 warps are woven by driving the same number of wefts into a warp. It is more preferable to use a warp and weft 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, reinforcing core material, reinforcing yarn, sacrificial yarn described later, etc.) are conveyed in the manufacturing process of the ion exchange membrane described later. The TD direction means 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 desired physical properties of 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 surface area (A) 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 ion exchange membrane where cations, electrolytes, etc. are not blocked by the reinforcing core material contained in the ion exchange membrane. can.

FIG. 3 is a schematic view for explaining the aperture ratio of the reinforcing core material constituting the ion exchange membrane. FIG. 3 is an enlargement of a part of the ion exchange membrane and shows only the arrangement of the reinforcing core members 21 and 22 in the region, and the other members are not shown.

It is 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, and the reinforced core material is taken 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 of 50 to 300 denier is used, and a weave density is 10 to 50 pieces /. It is more preferable that the plain weave is an inch and the thickness thereof is in the range of 50 to 100 μm. The aperture ratio of the ion exchange membrane containing the reinforcing core material is more preferably 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 is a hole that can serve as 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 the 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 the film is formed in both directions.

〔Production method〕
As a preferable method for producing the ion exchange membrane, a method having the following steps (1) to (6) can be mentioned.
(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 at least weaving a plurality of reinforcing core materials and a sacrificial yarn having a property of dissolving in an acid or an alkali and forming a communication hole, the adjacent reinforcing core materials can be connected to each other. The process of obtaining a reinforcing material with sacrificial threads placed between them.
(3) Step: A step of forming a film of the fluorine-containing polymer 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 inside.
(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 fluorine-containing polymer In the step (1), a fluorine-containing polymer is produced using the raw material monomers described in the first to third groups. In order to control the ion exchange capacity of the fluorinated polymer, the mixing ratio of the raw material monomers may be adjusted in the production of the fluorinated 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 yarn 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 being misaligned.

The sacrificial yarn has solubility in the manufacturing process of the membrane 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 thread.

(3) Step: Film formation step In the (3) step, the fluorine-containing polymer obtained in the above step (1) is filmed using an extruder. The film may have a single-layer structure, a two-layer structure of a sulfonic acid layer and a carboxylic acid layer, or 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 of 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, each of a plurality of films may be used. Further, it is preferable to co-extrude different kinds of films 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 fluorine-containing polymer 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 sulfonyl fluoride 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 if necessary, a heating source and a heating source and 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 the polymers while removing air between the layers 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. The fluoropolymer (third layer) is made 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 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 through 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 lamination variation 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 fluorine-containing polymer 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 fluorine-containing polymer having a carboxylic acid group precursor and a fluorine-containing polymer 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, which is described above. It may be laminated by a method, or the three layers of the first layer / fourth layer / 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 film body containing the fluorine-containing polymer having an ion exchange group can be formed on the reinforcing material.

Further, the ion exchange membrane preferably 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 or the like 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 and arrangement density of the convex portion 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 when the sacrificial yarn elutes, a communication hole is formed at the site.

The step (5) can be carried out by immersing the membrane body obtained in the step (4) in a hydrolyzed solution containing an acid or an alkali. As the hydrolyzed 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 takes 20 to 120 minutes.

Here, the step of forming the communication holes by eluting the sacrificial yarn will be described in more detail. 4 (a) and 4 (b) are schematic views for explaining a method of forming a communication hole of an ion exchange membrane.

In FIGS. 4A and 4B, only the communication hole 504 formed by the reinforcing thread 52, the sacrificial thread 504a, and the sacrificial thread 504a is shown, 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 the crochet reinforcing material. Then, the communication hole 504 is formed by elution of the sacrificial thread 504a in the step (5).

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

FIG. 4A 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 (6) step, 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 (5) step. A coating layer can be formed by applying and drying on the surface.

As a binder, a fluorine-containing polymer 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 fluorine-containing polymer 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.

The 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 by 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 uniformly apply it to the surface of the ion exchange membrane.

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 laminate with the electrode for electrolysis, and various microporous membranes can be applied.
The porosity of the microporous membrane of the present embodiment is not particularly limited, but can be, for example, 20 to 90, preferably 30 to 85. The porosity can be calculated by, for example, the following formula.
Porosity = (1- (weight of membrane in dry state) / (volume calculated from thickness, width, and 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 size, 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 about 100 points of observed hole diameters 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 Zircon Perl UTP 500 manufactured by Agfa (also referred to as Zircon membrane in the present embodiment), International Publication No. 2013-183584, International Publication No. 2016-203701. And so on.

In the present embodiment, the diaphragm preferably 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 includes 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 that can be introduced are as described above.

[Fixed area]
In the present embodiment, the electrode for electrolysis is fixed to at least one region on the surface of the diaphragm, and in the present specification, this one or more regions is also referred to as a fixed region. The fixed region in the present embodiment has a function of suppressing the separation of the electrolytic electrode and the diaphragm, and is not particularly limited as long as it is a portion for fixing the electrolytic electrode to the diaphragm. For example, the electrolytic electrode itself is the fixing means. In some cases, a fixed region is formed, and in some cases, a fixing member, which is a separate body from the electrode for electrolysis, serves as a fixing means to form a fixed region. The fixed region in the present embodiment may exist only at a position corresponding to the energized surface during electrolysis, or may extend to a position corresponding to the non-energized surface. The "energized surface" corresponds to a portion designed so that the electrolyte moves between the anode chamber and the cathode chamber. Further, the “non-energized surface” means a portion other than the energized surface.
Further, in the present embodiment, the ratio of the fixed region on the surface of the diaphragm (hereinafter, also simply referred to as “ratio α”) is more than 0% and less than 93%. The above ratio can be obtained as the ratio of the area of the fixed region (hereinafter, also simply referred to as “area S3”) to the area of the surface of the diaphragm (hereinafter, also simply referred to as “area S1”). In the present embodiment, the “surface of the diaphragm” means the surface of the surface of the diaphragm on the side where the electrode for electrolysis is present. The area of the portion of the surface of the diaphragm described above that is not covered with the electrode for electrolysis is also counted as the area S1.
From the viewpoint of making the diaphragm and the electrode for electrolysis more stable, the ratio α (= 100 × S3 / S1) is more than 0%, preferably 0.00000001% or more, and more preferably 0.000000001. % Or more. On the other hand, as in the prior art, when the entire surface of the contact surface between the diaphragm and the electrode is firmly adhered by a method such as thermocompression bonding (that is, when the above ratio is 100%), the contact surface in the electrode. The entire surface of the sill will be sunk into the diaphragm and physically adhered. Such an adhesive portion hinders the movement of sodium ions in the film, and the voltage rises significantly. In the present embodiment, from the viewpoint of sufficiently securing a space in which ions can freely move, the above ratio is less than 93%, preferably 90% or less, more preferably 70% or less, still more preferably. It is less than 60%.

In the present embodiment, from the viewpoint of obtaining better electrolytic performance, the area of the portion of the fixed region area (area S3) corresponding only to the energized surface (hereinafter, also simply referred to as “area S3'”) is adjusted. It is preferable to do so. That is, it is preferable to adjust the ratio of the area S3'(hereinafter, also simply referred to as "ratio β") to the area of the energized surface (hereinafter, also simply referred to as "area S2"). The area S2 can be specified as the surface area of the electrode for electrolysis (details will be described later). Specifically, in the present embodiment, the ratio β (= 100 × S3'/ S2) is preferably more than 0% and less than 100%, more preferably 0.000000001% or more and less than 83%, and further preferably 0. It is 0.0001% or more and 70% or less, and more preferably 0.00001% or more and 25% or less.

The above-mentioned ratios α and β can be measured, for example, as follows.
First, the area S1 on the surface of the diaphragm is calculated. Next, the area S2 of the electrode for electrolysis is calculated. Here, the areas S1 and S2 can be specified as the area when the laminate of the diaphragm and the electrode for electrolysis is viewed from the electrode side for electrolysis (see FIG. 15).
The shape of the electrode for electrolysis is not particularly limited, but it may have an opening, and it may be a case where the shape has an opening such as a mesh, and (i) the opening. If the rate is less than 90%, the perforated portion of S2 is also counted in the area S2, while (ii) if the perforation rate is 90% or more, sufficient electrolytic performance is ensured. Therefore, S2 is calculated by the area excluding the opening portion. The hole-opening ratio referred to here is a numerical value (%) obtained by dividing the total area S'of the hole-opened portion of the electrolytic electrode by the area S'of the electrolytic electrode obtained by counting the hole-opened portion as the area. ; 100 × S'/ S'').
The area of the fixed region (area S3 and area S3') will be described later.
As described above, the ratio α (%) of the region on the surface of the diaphragm can be obtained by calculating 100 × (S3 / S1). Further, the ratio β (%) of the area of the portion corresponding only to the energizing surface of the fixed region to the area of the energizing surface can be obtained by calculating 100 × (S3'/ S2).
More specifically, it can be measured by the method described in Examples described later.

The area S1 of the surface of the diaphragm specified as described above is not particularly limited, but is preferably 1 time or more and 5 times or less, more preferably 1 time or more and 4 times or less of the area S2 of the current-carrying surface. More preferably, it is 1 time or more and 3 times or less.

In the present embodiment, the fixed structure in the fixed region is not limited, but for example, the fixed structure illustrated below can be adopted. In addition, each fixed structure may adopt only one kind, or may adopt two or more kinds in combination.

In the present embodiment, it is preferable that at least a part of the electrode for electrolysis is fixed through the diaphragm in the fixed region. Such an embodiment will be described with reference to FIG. 5A.
In FIG. 5A, at least a part of the electrode 2 for electrolysis penetrates and is fixed to the diaphragm 3. As shown in FIG. 5A, a part of the electrode 2 for electrolysis penetrates the diaphragm 3. FIG. 5A shows an example in which the electrode 2 for electrolysis is a porous metal electrode. That is, although a plurality of parts of the electrode 2 for electrolysis are shown independently in FIG. 5A, they are connected and represent a cross section of an integral metal porous electrode (the same applies to FIGS. 6 to 9 below). .).
In such an electrode structure, for example, when the diaphragm 3 at a predetermined position (position that should be a fixed region) is pressed against the electrolytic electrode 2, the surface of the electrolytic electrode 2 is formed into an uneven structure or a hole structure. A part of the diaphragm 3 enters, and the concave portion on the electrode surface and the convex portion around the hole penetrate the diaphragm 3, and preferably, as shown in FIG. 5A, penetrate to the outer surface 3b of the diaphragm 3.

As described above, the fixed structure of FIG. 5A can be manufactured by pressing the diaphragm 3 against the electrode 2 for electrolysis. In this case, the diaphragm 3 is thermocompression-bonded and heat-sucked in a state of being softened by heating. As a result, the electrode 2 for electrolysis penetrates the diaphragm 3. Alternatively, the diaphragm 3 may be melted. In this case, in the state shown in FIG. 5B, it is preferable to suck the diaphragm 3 from the outer surface 2b side (back side) of the electrolytic electrode 2. The region where the diaphragm 3 is pressed against the electrode 2 for electrolysis constitutes the “fixed region”.

The fixed structure shown in FIG. 5A can be observed with a magnifying glass (loupe), an optical microscope, or an electron microscope. Further, since the electrode 2 for electrolysis penetrates the diaphragm 3, the fixed structure of FIG. 5A is obtained by conducting a continuity test using a tester or the like between the outer surface 3b of the diaphragm 3 and the outer surface 2b of the electrode 2 for electrolysis. It is possible to guess.

In FIG. 5A, it is preferable that the electrolytic solution in the anode chamber and the cathode chamber partitioned by the diaphragm does not permeate the penetrating portion. Therefore, it is preferable that the pore diameter of the penetrating portion is small enough to prevent the electrolytic solution from permeating. Specifically, when an electrolytic test is carried out, it is preferable that the performance equivalent to that of a diaphragm having no penetrating portion is exhibited. Alternatively, it is preferable to carry out processing to prevent the permeation of the electrolytic solution in the penetrating portion. It is preferable to use a material that does not elute or decompose due to the anode chamber electrolyte, the product generated in the anode chamber, the cathode chamber electrolyte, or the product generated in the cathode chamber in the penetrating portion. For example, EPDM and fluorine-based resins are preferable. A fluororesin having an ion exchange group is more preferable.

In the present embodiment, it is preferable that at least a part of the electrode for electrolysis is located and fixed inside the diaphragm in the fixed region. Such an embodiment will be described with reference to FIG. 6A.

As described above, the surface of the electrolysis electrode 2 has an uneven structure or a hole structure. In the embodiment shown in FIG. 6A, a part of the electrode surface penetrates and is fixed to the diaphragm 3 at a predetermined position (position to be a fixed region). The fixed structure shown in FIG. 6A can be manufactured by pressing the diaphragm 3 against the electrode 2 for electrolysis. In this case, it is preferable to form the fixed structure of FIG. 6A by thermocompression bonding and heat suction in a state where the diaphragm 3 is softened by heating. Alternatively, the diaphragm 3 can be melted to form the fixed structure of FIG. 6A. In this case, it is preferable to suck the diaphragm 3 from the outer surface 2b side (back side) of the electrolytic electrode 2.

The fixed structure shown in FIG. 6A can be observed with a magnifying glass (loupe), an optical microscope, or an electron microscope. In particular, a method of preparing a cross section by a microtome and observing the sample after embedding the sample is preferable. In the fixed structure shown in FIG. 6A, since the electrode 2 for electrolysis does not penetrate the diaphragm 3, continuity is confirmed by a continuity test between the outer surface 3b of the diaphragm 3 and the outer surface 2b of the electrode 2 for electrolysis. Not done.

In the present embodiment, it is preferable to further have a fixing member for fixing the diaphragm and the electrode for electrolysis. Such an embodiment will be described with reference to FIGS. 7A to 7C.

The fixing structure shown in FIG. 7A uses a fixing member 7 that is separate from the electrolysis electrode 2 and the diaphragm 3, and the fixing member 7 is fixed through the electrolysis electrode 2 and the diaphragm 3. .. The electrolytic electrode 2 does not necessarily have to be penetrated by the fixing member 7, and may be fixed by the fixing member 7 so as not to be separated from the diaphragm 2. The material of the fixing member 7 is not particularly limited, and as the fixing member 7, for example, a material made of metal, resin, or the like can be used. In the case of metal, nickel, nichrome, titanium, stainless steel (SUS) and the like can be mentioned. These oxides may be used. Examples of the resin include fluororesins (for example, PTFE (polytetrafluoroethylene), PFA (polymer of tetrafluoroethylene and perfluoroalkoxyethylene), ETFE (polymer of tetrafluoroethylene and ethylene), and the following. (Material of diaphragm 3), PVDF (polyfluorovinylidene), EPDM (ethylene / propylene / diene rubber), PP (polyethylene), PE (polypropylene), nylon, aramid and the like can be used.
In the present embodiment, for example, a thread-like fixing member (thread-like metal or resin) is used, and as shown in FIGS. 7B and 7C, a predetermined position between the outer surfaces 2b and 3b of the electrolytic electrode 2 and the diaphragm 3 is used. It can also be fixed by sewing (the position that should be the fixed area). The thread-like resin is not particularly limited, and examples thereof include PTFE threads and the like. It is also possible to fix the electrolytic electrode 2 and the diaphragm 3 by using a fixing mechanism such as a tacker.

In FIGS. 7A to 7C, it is preferable that the electrolytic solutions in the anode chamber and the cathode chamber partitioned by the diaphragm do not permeate the penetrating portion. Therefore, it is preferable that the pore diameter of the penetrating portion is small enough to prevent the electrolytic solution from permeating. Specifically, when an electrolytic test is carried out, it is preferable that the performance equivalent to that of a diaphragm having no penetrating portion is exhibited. Alternatively, it is preferable to carry out processing to prevent the permeation of the electrolytic solution in the penetrating portion. It is preferable to use a material that does not elute or decompose due to the anode chamber electrolyte, the product generated in the anode chamber, the cathode chamber electrolyte, or the product generated in the cathode chamber in the penetrating portion. For example, EPDM and fluorine-based resins are preferable. A fluororesin having an ion exchange group is more preferable.

The fixed structure shown in FIG. 8 is a structure in which an organic resin (adhesive layer) is interposed and fixed between the electrode 2 for electrolysis and the diaphragm 3. That is, in FIG. 8, the organic resin as the fixing member 7 is arranged at a predetermined position (position that should be a fixing region) between the electrolysis electrode 2 and the diaphragm 3 and fixed by adhesion. For example, the organic resin is applied to the inner surface 2a of the electrolytic electrode 2, the inner surface 3a of the diaphragm 3, or both or one of the inner surfaces 2a and 3a of the electrolytic electrode 2 and the diaphragm 3. Then, by laminating the electrolysis electrode 2 and the diaphragm 3, the fixed structure shown in FIG. 8 can be formed. The material of the organic resin is not particularly limited, but for example, a fluororesin (for example, PTFE, PFA, ETFE), a resin similar to the material constituting the diaphragm 3 described above, or the like can be used. In addition, a commercially available fluorine-based adhesive, PTFE dispersion, or the like can be used as appropriate. Furthermore, general-purpose vinyl acetate adhesives, ethylene vinyl acetate copolymer adhesives, acrylic resin adhesives, α-olefin adhesives, styrene butadiene rubber latex adhesives, vinyl chloride resin adhesives, chloroprene adhesives Agents, nitrile rubber adhesives, urethane rubber adhesives, epoxy adhesives, silicone resin adhesives, modified silicone adhesives, epoxy / modified silicone resin adhesives, silylated urethane resin adhesives, cyanoacrylate It is also possible to use a system adhesive or the like.
In the present embodiment, an organic resin that dissolves in the electrolytic solution or dissolves and decomposes during the electrolysis may be used. The organic resin that dissolves in the electrolytic solution or dissolves and decomposes during electrolysis is not limited to the following, but for example, vinyl acetate adhesive, ethylene vinyl acetate copolymer adhesive, acrylic resin adhesive, α-. Olefin adhesive, styrene butadiene rubber latex adhesive, vinyl chloride resin adhesive, chloroprene adhesive, nitrile rubber adhesive, urethane rubber adhesive, epoxy adhesive, silicone resin adhesive, modified silicone Examples thereof include based adhesives, epoxy / modified silicone resin based adhesives, silylated urethane resin based adhesives, and cyanoacrylate based adhesives.
The fixed structure shown in FIG. 8 can be observed with an optical microscope or an electron microscope. In particular, a method of preparing a cross section by a microtome and observing the sample after embedding the sample is preferable.

In the present embodiment, it is preferable that at least a part of the fixing member grips the diaphragm and the electrode for electrolysis from the outside. Such an embodiment will be described with reference to FIG. 9A.
The fixed structure shown in FIG. 9A is a structure in which the electrode 2 for electrolysis and the diaphragm 3 are gripped and fixed from the outside. That is, the outer surface 2b of the electrolytic electrode 2 and the outer surface 3b of the diaphragm 3 are sandwiched and fixed by the gripping member 7 as the fixing member 7. The fixed structure shown in FIG. 9A also includes a state in which the gripping member bites into the electrode 2 for electrolysis and the diaphragm 3. Examples of the gripping member include tapes, clips and the like.
In this embodiment, a gripping member that dissolves in the electrolytic solution may be used. Examples of the gripping member that dissolves in the electrolytic solution include PET tapes and clips, PVA tapes, and clips.

Unlike FIGS. 5 to 8, the fixed structure shown in FIG. 9A does not join the interface between the electrolytic electrode 2 and the diaphragm 3, and the inner surfaces 2a and 3a of the electrolytic electrode 2 and the diaphragm 3 are It is only in a state of being in contact with or facing each other, and by removing the gripping member, the fixed state of the electrode 2 for electrolysis and the diaphragm 3 can be released and separated.
Although not shown in FIG. 9A, the electrolytic electrode 2 and the diaphragm 3 can be fixed to the electrolytic cell by using a gripping member.
For example, a PTFE tape can be folded back and fixed so as to sandwich the diaphragm and the electrode.

Further, in the present embodiment, it is preferable that at least a part of the fixing member fixes the diaphragm and the electrode for electrolysis by a magnetic force. Such an embodiment will be described with reference to FIG. 9B.
The fixed structure shown in FIG. 9B is a structure in which the electrode 2 for electrolysis and the diaphragm 3 are gripped and fixed from the outside. The difference from FIG. 9A is that a pair of magnets are used as the gripping member as the fixing member. In the aspect of the fixed structure shown in FIG. 9B, after the laminated body 1 is attached to the electrolytic cell, the gripping member may be left as it is or may be removed from the laminated body 1 when the electrolytic cell is in operation.
Although not shown in FIG. 9B, the electrolytic electrode 2 and the diaphragm 3 can be fixed to the electrolytic cell by using a gripping member. When a magnetic material that adheres to a magnet is used as a part of the material of the electrolytic cell, one gripping material is installed on the diaphragm surface side, and the electrolytic cell, the electrode 2 for electrolysis, and the diaphragm 3 are sandwiched. It can also be fixed.

It should be noted that a plurality of fixed areas can be provided. That is, 1, 2, 3, ... n fixed regions can be arranged from the contour side of the laminated body 1 toward the inside. n is an integer of 1 or more. Further, the m-th (m <n) fixed region and the L-th (m <L ≦ n) fixed region can be formed by different fixed patterns.

The fixed region formed in the energized portion preferably has a line-symmetrical shape. As a result, stress concentration tends to be suppressed. For example, assuming that the two orthogonal directions are the X direction and the Y direction, one is arranged in each of the X direction and the Y direction, or a plurality of ones are arranged in each of the X direction and the Y direction at equal intervals to form a fixed region. can do. The number of fixed regions in the X and Y directions is not limited, but it is preferably 100 or less in each of the X and Y directions. Further, from the viewpoint of ensuring the surfaceness of the energized portion, the number of fixed regions in the X direction and the Y direction is preferably 50 or less, respectively.

When the fixed structure shown in FIGS. 5A and 7 is provided in the fixed region of the present embodiment, a sealing material is provided on the film surface of the fixed region from the viewpoint of preventing a short circuit due to contact between the anode and the cathode. It is preferable to apply. As the sealing material, for example, the material described in the above adhesive can be used.

When the fixing member is used, when the area S3 and the area S3'are obtained, the overlapping portion is not counted in the area S3 and the area S3'for the portion where the fixing member overlaps. For example, when the above-mentioned PTFE yarn is fixed as a fixing member, the portion where the PTFE yarn intersects with each other is not counted as an overlapping portion in the area. Further, when the above-mentioned PTFE tape is fixed as a fixing member, the portion where the PTFE tapes overlap with each other is not counted as an overlapping portion in the area.
Further, when the above-mentioned PTFE thread or adhesive is fixed as a fixing member, the area existing on the back side of the electrode for electrolysis and / or the diaphragm is also counted in the area S3 and the area S3'.

As described above, the laminate in the present embodiment may have various fixed regions at various positions, but in particular, in a portion where the fixed region does not exist (non-fixed region), the electrode for electrolysis is described above. It is preferable that the "force applied" is satisfied. That is, it is preferable that the force applied per unit mass / unit area of the electrode for electrolysis in the non-fixed region is less than 1.5 N / mg · cm ² .

[Electrolytic cell]
The electrolytic cell of the present embodiment includes the laminate of the present embodiment. 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.

[Electrolytic cell]
FIG. 10 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. It includes a cathode 21 and. If necessary, the base material 18a and the reverse current absorbing layer 18b formed on the base material 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, 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. The entire surface of the cathode 21 is preferably coated with a catalyst layer for the 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. 11 is a cross-sectional view of two adjacent electrolytic cells 1 in the electrolytic cell 4. FIG. 12 shows the electrolytic cell 4. FIG. 13 shows a process of assembling the electrolytic cell 4. As shown in FIG. 11, 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 a cation exchange membrane 2. As shown in FIG. 12, 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. 13, 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 to 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 to 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. When the electrode for electrolysis in the present embodiment is inserted into 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 unit that supplies the electrolytic solution to the anode chamber 10 and the anode-side electrolytic solution supply unit, 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 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 a titanium-based electrode whose surface is coated with an oxide containing ruthenium, iridium, and titanium as components.
As the shape, any of punching metal, non-woven metal, foamed metal, expanded metal, perforated metal foil formed by electroforming, so-called woven mesh made by knitting 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 feeding body 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 reduced catalyst coating thickness. Furthermore, a used anode can also be used.
As the shape, any one such as punching metal, non-woven metal, foamed metal, expanded metal, perforated metal foil formed by electroforming, and so-called woven mesh made by knitting a metal wire 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 electrolyte 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 solution 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. 10, and "downward" means a downward direction in the electrolytic cell 1 of FIG.

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 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 specific gravity between gas and liquid is created 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. 10, a current collector may be separately provided inside the anode chamber 10. The current collector may have the same material and structure 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 electrode for electrolysis in the present embodiment is inserted into the cathode side, 21 functions as a cathode feeder, and when the electrode for electrolysis in 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 respective parts constituting the cathode chamber 20, the same parts as those constituting the anode chamber 10 will not be described.

(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 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, a nickel alloy, iron, or stainless steel plated with nickel may be used.
As the shape, any one such as punching metal, non-woven metal, foamed metal, expanded metal, perforated metal foil formed by electroforming, and so-called woven mesh made by knitting a metal wire can be used.

(Cathode feeder)
When the electrode for electrolysis in the present embodiment is inserted into the cathode side, the cathode feeding body 21 is provided in the frame of the cathode chamber 20. The cathode feeding body 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, which is not catalyst-coated, may be plated with nickel. As the base material of the cathode feeding body 21, nickel, a nickel alloy, iron, or stainless steel plated with nickel may be used.
As the shape, any one such as punching metal, non-woven metal, foamed metal, expanded metal, perforated metal foil formed by electroforming, and so-called woven mesh made by knitting a metal wire 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 membrane 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 according to the present embodiment is installed in the electrolytic cell, the electrode for electrolysis is stabilized by the pressing pressure by the metal elastic body 22. Can be maintained 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 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 has, for example, a plate shape. 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 surfaces 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 body 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 included in one electrolytic cell and the cathode-side gasket of the electrolytic cell adjacent thereto sandwich the ion exchange membrane 2 (see FIGS. 10 and 11). 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 seals 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 corrosive electrolytes, generated gases, 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 crosslinked 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 (contact 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 forming the anode chamber 10 or the cathode chamber frame forming the cathode chamber 20. Then, for example, when two electrolytic cells 1 are connected via an ion exchange membrane 2 (see FIG. 11), each electrolytic cell 1 to which a 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 electrolysis from leaking to the outside of the electrolytic cell 1.

(Ion exchange membrane 2)
The ion exchange membrane 2 is as described in the above section of the ion exchange membrane.

(Water electrolysis)
The electrolytic cell of 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 evolution 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.

(1) Electrolysis evaluation (voltage (V), current efficiency (%))
The electrolysis performance was evaluated by the following electrolysis experiment.
A titanium anode cell (anode terminal cell) having an anode chamber in which an anode was installed and a cathode cell having a nickel cathode chamber (cathode terminal cell) in which a cathode was installed were faced to each other. A pair of gaskets were placed between the cells, and an ion exchange membrane was sandwiched between the pair of gaskets. Then, the anode cell, the gasket, the ion exchange membrane, the gasket and the cathode were brought into close contact with each other to obtain an electrolytic cell.
The anode was prepared by applying a mixed solution of ruthenium chloride, iridium chloride, and titanium tetrachloride on a titanium substrate that had been blasted and acid-etched as a pretreatment, dried, and fired. The anode was fixed to the anode chamber by welding. As the cathode, those described in each Example and Comparative Example were used. Nickel expanded metal was used as the current collector in the cathode chamber. The size of the current collector was 95 mm in length × 110 mm in width. As the metal elastic body, a mattress woven with fine nickel wire was used. A mattress, which is a metal elastic body, was placed on the current collector. A nickel wire having a diameter of 150 μm was plain-woven with a 40-mesh opening, and the four corners of the Ni-mesh were fixed to the current collector with a string made of Teflon (registered trademark). This Ni mesh was used as a feeding body. In this electrolytic cell, the repulsive force of the mattress, which is a metal elastic body, was used to form a zero gap structure. As the gasket, a rubber gasket made of EPDM (ethylene propylene diene) was used. The following ion exchange membrane was used as the diaphragm.
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. 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 ₂ ) OCF ₂ CF ₂ SO ₂ F.

Using these resins A and B, a two-layer film X having a resin A layer thickness of 15 μm and a resin B layer thickness 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 depressurizing for 2 minutes under the conditions of a hot plate surface temperature of 223 ° C. and a depressurization 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 counter ion 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 an average particle size (primary particle size) of 1 μm was added to a 5% by mass ethanol solution of the acid-type resin of resin B to prepare a dispersed suspension, and a suspension spray method was performed. Then, spraying was performed on both sides of the above composite film to form a zirconium oxide coating on the surface of the composite film to obtain an ion exchange film. The coating density of zirconium oxide was measured by fluorescent X-ray measurement and found to be 0.5 mg / cm ² . The average particle size was measured by a particle size distribution meter (for example, "SALD (registered trademark) 2200" manufactured by Shimadzu Corporation).

The salt was electrolyzed using the above electrolytic cell. The salt water concentration (sodium chloride concentration) in the anode chamber was adjusted to 205 g / L. The sodium hydroxide concentration in the cathode chamber was adjusted to 32% by mass. The temperatures of the anode chamber and the cathode chamber were adjusted so that the temperature in each electrolytic cell was 90 ° C. Salt electrolysis was performed at a current density of 6 kA / m ² , and the voltage and current efficiency were measured. Here, the current efficiency is the ratio of the amount of caustic soda produced to the flowing current, and when the flowing current causes impurity ions or hydroxide ions to move through the ion exchange membrane instead of sodium ions, the current Efficiency is reduced. The current efficiency was determined by dividing the number of moles of caustic soda produced in a certain period of time by the number of moles of electrons of the current flowing during that period. The number of moles of caustic soda was determined by collecting the caustic soda produced by electrolysis in a plastic tank and measuring its mass.

(2) Handleability (sensitivity evaluation)
(A) The above-mentioned ion exchange membrane (diaphragm) was cut to a size of 170 mm square, and the electrodes obtained in Examples and Comparative Examples described later were cut to 95 × 110 mm. The ion exchange membrane and the electrode were laminated and statically placed on a Teflon (registered trademark) plate. The distance between the anode cell and the cathode cell used in the electrolysis evaluation was set to about 3 cm, and the static laminated body was lifted and inserted and sandwiched between them. When performing this operation, it was confirmed while operating whether the electrodes did not shift or fall.

(B) The laminate was statically placed on a Teflon (registered trademark) plate in the same manner as in (A) above. The two adjacent corners of the film portion of the laminate were held by hand and lifted so that the laminate was vertical. From this state, the two corners held by hand were moved so as to come close to each other so that the film became convex and concave. This operation was repeated once more, and the followability of the electrode to the film was confirmed. The results were evaluated on a scale of 1 to 4 based on the following indicators.
1: Good handling 2: Possible to handle 3: Difficult to handle 4: Almost impossible to handle Here, as described later, the handleability of the samples of Examples 4 and 6 was evaluated even if they were the same size as the large electrolytic cell. The evaluation results of Examples 4 and 6 were used as an index for evaluating the difference between the evaluations of (A) and (B) above and the large size. That is, when the results of evaluating the small laminated body were "1" and "2", it was evaluated that the handleability was good even when the large size was used.

(3) Ratio of fixed region The area of the surface of the ion exchange membrane facing the electrode for electrolysis (the total of the portion corresponding to the energized surface and the portion corresponding to the non-energized surface) was calculated as the area S1. Next, the area of the electrode for electrolysis was calculated as the area S2 of the current-carrying surface. The areas S1 and S2 were specified by the area when the laminate of the ion exchange membrane and the electrode for electrolysis was viewed from the electrode side for electrolysis (see FIG. 15). The shape of the electrode for electrolysis was less than 90% even if it had holes, so the electrode for electrolysis was regarded as a flat plate (the holes are also counted in the area). did).
The area S3 of the fixed region was also specified as the area when the laminated body was viewed from above as shown in FIG. 15 (the same applies to the area S3'of the portion corresponding only to the energized surface). When the PTFE tape, which will be described later, is fixed as a fixing member, the overlapping portion of the tape is not counted in the area. Further, when the PTFE thread or adhesive described later was fixed as a fixing member, the area was counted including the area existing on the back side of the electrode and the diaphragm.
As described above, 100 × (S3 / S1) was calculated as the ratio α (%) of the area of the fixed region to the area of the surface of the ion exchange membrane facing the electrode for electrolysis. Further, 100 × S3 ′ / S2 was calculated as the ratio β of the area of the portion corresponding only to the energizing surface of the fixed region to the area of the energizing surface.

[Example 1]
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 mean roughness Ra of the roughened surface was 0.96 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 further installed on the coating roll. The electrode base material was applied between the second coating roll and the uppermost PVC roller (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 electrode produced in Example 1 was 24 μm. The thickness of the catalyst layer containing ruthenium oxide and cerium oxide was 8 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.
The electrode produced by the above method was cut into a size of 95 mm in length and 110 mm in width for electrolytic evaluation. The roughened surface of the electrode was placed at a position substantially at the center of the ion exchange membrane (size 160 mm × 160 mm) equilibrated with a 0.1 N NaOH aqueous solution on the carboxylic acid layer side so as to face each other. Using a PTFE tape (manufactured by Nitto Denko), as shown in FIG. 15 (however, FIG. 15 is only a schematic diagram for explanation and the dimensions are not always accurate. The same applies to the following figures). The four sides were fixed so as to sandwich the exchange membrane and the electrode. In Example 1, the PTFE tape was a fixing member, the proportion α was 60%, and the proportion β was 1.0%.
Even if the four corners of the membrane part of the membrane-integrated electrode in which the membrane and the electrode are integrated are pinched so that the electrode is on the ground side and the membrane-integrated electrode is hung parallel to the ground, the electrode may peel off or shift. I didn't do it. Further, even if both ends of one side were pinched and the membrane-integrated electrode was hung so as to be perpendicular to the ground, the electrode did not peel off or shift.
The membrane-integrated electrode was sandwiched between the anode cell and the cathode cell so that the surface to which the electrode was attached was on the cathode chamber side. As for the cross-sectional structure, a zero gap structure is formed by arranging a current collector, a mattress, a nickel mesh feeding body, an electrode, a film, and an anode in this order from the cathode chamber side.
The obtained electrodes were evaluated. The results are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also relatively good at "2".

[Example 2]
As shown in FIG. 16, the evaluation was carried out in the same manner as in Example 1 except that the area of the PTFE tape overlapping the electrolytic surface was increased. That is, in Example 2, since the area of the PTFE tape was increased in the in-plane direction of the electrode for electrolysis, the area of the electrolysis surface in the electrode for electrolysis was smaller than that in Example 1. In Example 2, the proportion α was 69% and the proportion β was 23%. The results of the evaluation are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also good at "1".

[Example 3]
As shown in FIG. 17, the evaluation was carried out in the same manner as in Example 1 except that the area of the PTFE tape overlapping the electrolytic surface was increased. That is, in Example 3, since the area of the PTFE tape was increased in the in-plane direction of the electrode for electrolysis, the area of the electrolysis surface in the electrode for electrolysis was smaller than that in Example 1. In Example 3, the proportion α was 87% and the proportion β was 67%. The results of the evaluation are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also good at "1".

[Example 4]
The same electrodes as in Example 1 were prepared and cut into a size of 95 mm in length and 110 mm in width for electrolysis evaluation. The roughened surface of the electrode was placed at a position substantially at the center of the ion exchange membrane (size 160 mm × 160 mm) equilibrated with a 0.1 N NaOH aqueous solution on the carboxylic acid layer side so as to face each other. As shown in FIG. 18, the ion exchange membrane and the electrode were sewn so as to extend vertically on the left side of the electrode using a thread made of PTFE. A PTFE thread is passed from the back side to the front side of the paper surface in FIG. 18 from a portion 10 mm vertically and 10 mm horizontally from the corner of the electrode, and is penetrated from the front side to the back side of the paper surface at a portion 35 mm vertically and 10 mm horizontally. The thread was penetrated from the back side to the front side of the paper again at the portion of 60 mm in length and 10 mm in width, and was penetrated from the front side to the back side of the paper surface in the portion of 85 mm in length and 10 mm in width. In the portion where the thread penetrates the ion exchange membrane, a copolymer of CF ₂ = CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₂ ) OCF ₂ CF ₂ SO ₂ F has an ion exchange capacity of 1.03 mg equivalent / A solution in which the acid type resin S of the resin of g was dispersed in ethanol so as to be 5% by mass was applied.
As described above, in Example 4, the ratio α was 0.35% and the ratio β was 0.86%.
Even if the four corners of the membrane part of the membrane-integrated electrode in which the membrane and the electrode are integrated are pinched so that the electrode is on the ground side and the membrane-integrated electrode is hung parallel to the ground, the electrode does not fall. Even if both ends of one side were pinched and the membrane-integrated electrode was hung so as to be perpendicular to the ground, the electrode did not fall.
The obtained electrodes were evaluated. The results are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also relatively good at "2".

Further, in Example 4, an ion exchange membrane and an electrode changed to a large size were prepared. Four ion exchange membranes having a length of 1.5 m and a width of 2.5 m and four cathodes having a length of 0.3 m and a width of 2.4 m were prepared. The cathodes were arranged without gaps on the carboxylic acid layer side of the ion exchange membrane, and the cathode and the ion exchange membrane were adhered with PTFE yarn to prepare a laminate. In this example, the proportion α was 0.013% and the proportion β was 0.017%.
The operation of mounting the membrane-integrated electrode, in which the membrane and the electrode were integrated, into a large electrolytic cell was carried out, but the mounting was successful.

[Example 5]
The same electrodes as in Example 1 were prepared and cut into a size of 95 mm in length and 110 mm in width for electrolysis evaluation. The roughened surface of the electrode was placed at a position substantially at the center of the ion exchange membrane (size 160 mm × 160 mm) equilibrated with a 0.1 N NaOH aqueous solution on the carboxylic acid layer side so as to face each other. The ion exchange membrane and the electrode were fixed using the polypropylene fixing resin shown in FIG. That is, it is installed at one place 20 mm vertically and 20 mm horizontally from the corner of the electrode, and one more place 20 mm vertically and 20 mm horizontally from the corner located below it, for a total of two places. did. The same solution as in Example 4 was applied to the portion where the fixing resin penetrated the ion exchange membrane.
As described above, in Example 5, the fixing resin and the resin S served as the fixing members, and the ratio α was 0.47% and the ratio β was 1.1%.
Even if the four corners of the membrane part of the membrane-integrated electrode in which the membrane and the electrode are integrated are pinched so that the electrode is on the ground side and the membrane-integrated electrode is hung parallel to the ground, the electrode does not fall. Even if both ends of one side were pinched and the membrane-integrated electrode was hung so as to be perpendicular to the ground, the electrode did not fall.
The obtained electrodes were evaluated. The results are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also relatively good at "2".

[Example 6]
The same electrodes as in Example 1 were prepared and cut into a size of 95 mm in length and 110 mm in width for electrolysis evaluation. The roughened surface of the electrode was placed at a position substantially at the center of the ion exchange membrane (size 160 mm × 160 mm) equilibrated with a 0.1 N NaOH aqueous solution on the carboxylic acid layer side so as to face each other. As shown in FIG. 20, the ion exchange membrane and the electrode were fixed using a cyanoacrylate adhesive (trade name: Aron Alpha, Toagosei Co., Ltd.). That is, five places (all at equal intervals) on one vertical side of the electrode and eight places (all at equal intervals) on one horizontal side of the electrode were fixed with an adhesive.
As described above, in Example 6, the adhesive became a fixing member, the ratio α was 0.78%, and the ratio β was 1.9%.
Even if the four corners of the membrane part of the membrane-integrated electrode in which the membrane and the electrode are integrated are pinched so that the electrode is on the ground side and the membrane-integrated electrode is hung parallel to the ground, the electrode does not fall. Even if both ends of one side were pinched and the membrane-integrated electrode was hung so as to be perpendicular to the ground, the electrode did not fall.
The obtained electrodes were evaluated. The results are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also relatively good at "1".

Further, in Example 6, an ion exchange membrane and an electrode changed to a large size were prepared. Four ion exchange membranes having a length of 1.5 m and a width of 2.5 m and four cathodes having a length of 0.3 m and a width of 2.4 m were prepared. The four cathodes were formed into one large cathode (1.2 m in length and 2.4 m in width) by connecting the edges of one side to each other with the above-mentioned adhesive. This large cathode was adhered to the central portion of the ion exchange membrane on the carboxylic acid layer side with Aron Alpha to prepare a laminate. That is, as in FIG. 20, 5 places (all at equal intervals) on one vertical side of the electrode and 8 places (all at equal intervals) on one side of the electrode were fixed with an adhesive. In this example, the proportion α was 0.019% and the proportion β was 0.024%.
The operation of mounting the membrane-integrated electrode, in which the membrane and the electrode were integrated, into a large electrolytic cell was carried out, but the mounting was successful.

[Example 7]
The same electrodes as in Example 1 were prepared and cut into a size of 95 mm in length and 110 mm in width for electrolysis evaluation. The roughened surface of the electrode was placed at a position substantially at the center of the ion exchange membrane (size 160 mm × 160 mm) equilibrated with a 0.1 N NaOH aqueous solution on the carboxylic acid layer side so as to face each other. The same solution as in Example 4 was applied to fix the ion exchange membrane and the electrode. That is, it is installed at one place 20 mm vertically and 20 mm horizontally from the corner of the electrode, and one more place 20 mm vertically and 20 mm horizontally from the corner located below it, for a total of two places. (See FIG. 19).
As described above, in Example 7, the resin S served as a fixing member, the ratio α was 2.0%, and the ratio β was 4.8%.
Even if the four corners of the membrane part of the membrane-integrated electrode in which the membrane and the electrode are integrated are pinched so that the electrode is on the ground side and the membrane-integrated electrode is hung parallel to the ground, the electrode does not fall. Even if both ends of one side were pinched and the membrane-integrated electrode was hung so as to be perpendicular to the ground, the electrode did not fall.
The obtained electrodes were evaluated. The results are shown in Table 1.
It showed low voltage and high current efficiency. The handleability was also relatively good at "2".

[Comparative Example 1]
The evaluation was carried out in the same manner as in Example 1 except that the area of the PTFE tape overlapping the electrolytic surface was increased. That is, in Comparative Example 1, since the area of the PTFE tape was increased in the in-plane direction of the electrode for electrolysis, the area of the electrolysis surface in the electrode for electrolysis was smaller than that in Example 1. In Comparative Example 1, the ratio α was 93% and the ratio β was 83%. The results of the evaluation are shown in Table 1.
The voltage was high and the current efficiency was low. The handleability was as good as "1".

[Comparative Example 2]
The evaluation was carried out in the same manner as in Example 1 except that the area of the PTFE tape overlapping the electrolytic surface was increased. The results of the evaluation are shown in Table 1. That is, in Comparative Example 2, the area of the PTFE tape was increased in the in-plane direction of the electrode for electrolysis.
In Comparative Example 2, the ratio α and the ratio β were 100%, and since the entire electrolytic surface was a fixed region covered with PTFE, the electrolytic solution could not be supplied and electrolysis could not be performed. The handleability was as good as "1".

[Comparative Example 3]
The evaluation was carried out in the same manner as in Example 1 except that the PTFE tape was not used, that is, the ratio α and the ratio β were 0%. The results of the evaluation are shown in Table 1.
It showed low voltage and high current efficiency. On the other hand, since the fixed region of the diaphragm and the electrode did not exist, the diaphragm and the electrode could not be handled as a laminated body (integral body), and the handleability was "4".

The evaluation results of Examples 1 to 7 and Comparative Examples 1 to 3 are also shown in Table 1 below.

Explanation of reference numerals with respect to FIG. 1 10 ... Electrode electrode base material for electrolysis, 20 ... First layer, 30 ... Second layer, 100 ... Electrode for electrolysis.

Description of Reference numerals for FIGS. Material, 100 ... Electrolytic cell, 200 ... Anode, 300 ... Cathode, 52 ... Reinforcing thread, 504a ... Sacrificial thread, 504 ... Communication hole 504.

Explanation of reference numerals with respect to FIGS. 5 to 9 1 ... Laminated body, 2 ... Electrolytic electrode, 2a ... Inner surface of electrolytic electrode, 2b ... Outer surface of electrolytic electrode, 3 ... Septum 3, 3a ... Inner surface of the diaphragm, 3b ... Outer surface of the diaphragm, 7 ... Fixing member.

Explanation of reference numerals with respect to FIGS. 10 to 14 1 ... Electrolytic cell, 2 ... Ion exchange film, 4 ... Electrolytic cell, 5 ... Press, 6 ... Cathode terminal, 7 ... Anode terminal 10, 10 ... Anode chamber, 11 ... Anode, 12 ... Anode 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 ... Anode structure for electrolysis.

Claims (10)

With the diaphragm,
An electrode for electrolysis fixed to at least one region on the surface of the diaphragm,
Have,
The ratio α of the area S3 of the region to the area S1 of the surface of the diaphragm is more than 0% and less than 93% as 100 × S3 / S1 .
A laminated body in which the ratio β of the area S3'of the portion of the region corresponding only to the current-carrying surface to the area S2 of the current-carrying surface is 0.000001% or more and 70% or less as 100 × S3'/ S2 . 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, From Re, Os, Al, In, Sn, Sb, Ga, Ge, B, C, N, O, Si, P, S, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb and Dy The laminate according to claim 1, which comprises at least one catalyst component selected from the group. The laminate according to claim 1 or 2, wherein at least a part of the electrode for electrolysis is fixed through the diaphragm in the region. The laminate according to any one of claims 1 to 3, wherein at least a part of the electrode for electrolysis is located and fixed inside the diaphragm in the region. The laminate according to any one of claims 1 to 4, further comprising a fixing member for fixing the diaphragm and the electrode for electrolysis. The laminate according to claim 5, wherein at least a part of the fixing member grips the diaphragm and the electrode for electrolysis from the outside. The laminate according to claim 5 or 6, wherein at least a part of the fixing member magnetically fixes the diaphragm and the electrode for electrolysis. The diaphragm contains an ion exchange membrane containing an organic resin in the surface layer.
The laminate according to any one of claims 1 to 7, wherein the organic resin is present in the region. The invention according to any one of claims 1 to 8, wherein the diaphragm includes a first ion exchange resin layer and a second ion exchange resin layer having an EW different from that of the first ion exchange resin layer. Laminated body. The invention according to any one of claims 1 to 8, wherein the diaphragm includes 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 laminate described.

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