JP6862232B2 - A method for manufacturing a diaphragm and a method for manufacturing an electrode unit using the diaphragm. - Google Patents

Description

An embodiment of the present invention relates to a method for producing a diaphragm used for electrolysis and a method for producing an electrode unit using the same.

As an electrolyzer that produces alkaline ionized water, ozone water, hypochlorous acid water, or the like, an electrolyzer having a three-chamber type electrolytic cell is used. In the three-chamber type electrolytic cell, the electrolytic cell is divided into an anode chamber, an intermediate chamber, and a cathode chamber by a cation exchange membrane such as Nafion and an anion exchange membrane having a quaternary ammonium salt or a quaternary phosphonium salt. Be done. An anode and a cathode having a penetrating porous structure are arranged in the anode chamber and the cathode chamber, respectively.

In such an electrolyzer, for example, a saline solution is passed through the intermediate chamber, water is passed through the left and right cathode chambers and the anode chamber, and the saline solution in the intermediate chamber is electrolyzed by the cathode and the anode, thereby generating the anode chamber. Hypochlorite water is produced from chlorine gas, and sodium hydroxide water is produced in the cathode chamber. The generated hypochlorous acid water is used as sterilizing water, and the sodium hydroxide water is used as washing water.

In such a three-chamber type electrolytic cell, the anion exchange membrane is easily deteriorated by chlorine and hypochlorous acid. Therefore, an overlap or a notch is made between the porous anode prepared by punching or the like and the anion exchange membrane. There was a technique to reduce deterioration due to chlorine by inserting a non-woven fabric. Further, it is known that a porous membrane is arranged so as not to block a large number of perforated electrodes.

However, with the above structure, deterioration of the electrolytic cell was unavoidable due to operation for a very long period of time.

Japanese Unexamined Patent Publication No. 2012-172199 Japanese Unexamined Patent Publication No. 2006-322053 Japanese Unexamined Patent Publication No. 11-100688

An object to be solved by the present invention is to provide a highly efficient and long-life diaphragm manufacturing method and an electrode unit manufacturing method.

According to the embodiment, a step of immersing a hydrophobic porous film containing a fluorine atom in a hydroalcohol-containing dispersion of alumina hydrate particles, and
The step of removing the porous membrane from the dispersion and
A step of heating the porous membrane coated with the dispersion liquid to form a hydrophobic alumina hydrate layer on the surface of the porous membrane, and a step of forming the hydrophobic alumina hydrate layer.
Provided is a method for producing a diaphragm, which comprises a step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution to make it hydrophilic.

FIG. 1 is a flow chart showing a method for manufacturing a diaphragm according to the first embodiment. FIG. 2 is a schematic view of the electrode unit according to the second embodiment. FIG. 3 is a flow chart showing a method of manufacturing the electrode unit according to the second embodiment. FIG. 4 is a flow chart showing a method of manufacturing the electrolyzed water generator according to the third embodiment. FIG. 5 is a schematic view showing an electrolyzed water generator according to an embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

It should be noted that the same reference numerals are given to common configurations throughout the embodiment, and duplicate description will be omitted. In addition, each figure is a schematic view for facilitating the understanding of the embodiment, and the shape, dimensions, ratio, etc. thereof may differ from those of the actual device, but these are based on the following explanation and known techniques. The design can be changed as appropriate.

(First Embodiment)
FIG. 1 shows a flow chart showing a method for manufacturing a diaphragm according to the first embodiment.

As shown in FIG. 1, the method for producing a diaphragm according to the embodiment includes a step (BL11) of immersing a porous membrane containing a fluorine atom in a hydrous alcohol dispersion of alumina hydrate particles and dispersing the porous membrane. A step of taking out from the liquid (BL12), a step of heating the porous membrane coated with the dispersion liquid to form an alumina hydrate layer on the surface of the porous membrane (BL13), and an alumina hydrate layer were formed. It has a step (BL14) of immersing the porous membrane in an acidic aqueous solution.
In BL11, the hydrophobic porous membrane is brought into contact with the hydrophobic alumina hydrate particles dispersed in the hydroalcohol. The hydroalcohol-containing dispersion of alumina hydrate particles has good dispersibility and is difficult to gel, so that it is easy to handle. In BL12, a coating layer of a hydrous alcohol dispersion of hydrophobic alumina hydrate particles is formed on the surface of a hydrophobic porous film. In BL13, the alumina hydrate particles in the coating layer are fused by heating to form an alumina hydrate coating layer that is difficult to peel off. In BL14, the hydrophobic group of the alumina hydrate particles is removed to become hydrophilic and stabilized. A porous diaphragm containing a fluorine atom coated with the alumina hydrate according to the first embodiment can be obtained.

By using the method according to the embodiment, the hydrophobic porous membrane can be easily and uniformly coated with alumina hydrate, and hydrophilicity can be easily achieved. As a result, the permeability of chlorine ions can be improved and the permeation of sodium ions can be suppressed. Therefore, according to the embodiment, electrolysis can be performed efficiently, and a porous diaphragm can be obtained with a long life.

The porous membrane used in the embodiment is a membrane having a plurality of through holes, and it is also possible to have an opening that does not penetrate.

The hydrous alcohol dispersion used in the embodiment can be obtained, for example, by dispersing an alumina hydrate particle gel in an alcohol solution or an alcohol aqueous solution. The water content of the hydrous alcohol dispersion can be, for example, 0.1% to 80%.

Boehmite or pseudo-boehmite can be used as the alumina hydrate. Further, the alumina hydrate particles can be coated with a hydrophobic group.
Alumina hydrate can be represented by the composition formula Al ₂ O ₃ · (H ₂ O) _x (x = 1-2).

Preferably, x = 1 to 1.5, and more preferably x = 1 to 1.3. The closer x is to 1, the greater the ratio of boehmite.

The composition can determine the amount as _{Al 2} O ₃ by measuring the content of aluminum by elemental analysis.

Specifically, a part of the porous membrane is boiled in a mixed solution of hydrochloric acid and nitric acid to completely dissolve aluminum. The aluminum content is quantified by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy). Next, the water that is weakly adsorbed on a part of the porous membrane under a vacuum at room temperature is removed. Next, the value of x can be determined by analyzing the amount of water desorbed at 130 to 1000 ° C. with a thermal analyzer and measuring with a mass spectrometer or a gas chromatograph.

It can have a step of heating with hot water or steam. When treated with hot water of 70 ° C or higher, boehmite tends to be the main component. More preferably, it is 80 ° C. or higher, and even more preferably 100 ° C. or higher. If the temperature exceeds 100 ° C., pressurization can be performed. Boehmite fine particles also include pseudo-boehmite fine particles. Pseudo-boehmite has a higher water content than boehmite and easily becomes boehmite by heating. The heating is preferably 80 ° C. or higher and 300 ° C. or lower, more preferably 120 ° C. or higher, still more preferably 150 ° C. or higher.

In the method for producing a diaphragm according to the embodiment, the porous membrane can be surface-treated in advance by performing plasma treatment, electron beam treatment, or UV ozone treatment. By these treatments, hydrophilic groups such as hydroxyl groups and carboxyl groups are introduced on the surface of the porous film, the bond with the alumina hydrate coating layer becomes stronger, and the peeling becomes more difficult.

As the acidic aqueous solution, 0.1% by weight to 10% by weight of hydrochloric acid can be used.
If the acidic aqueous solution is less than 0.1% by weight, it tends to take time to remove the hydrophobic group, and if it exceeds 10% by weight, the treatment time tends to be saturated.

Polyvinylidene difluoride or polyvinylidene fluoroethylene can be used as the porous membrane. These are chemically stable and easily form a porous membrane.

The pulling method can be used as a step of taking out into the air. When the pulling method is used, both sides can be coated in the same manner, so that more uniform coating is possible.

The average pore size of the porous membrane can be 100 nm to 300 nm. If the average pore size is smaller than 100 nm, the amount of ion permeation tends to be too small when coated with alumina hydrate, and if it is larger than 300 nm, the amount of ion permeation tends to be too large.
The major axis of the primary particles of alumina hydrate can be 10 nm to 100 nm. If the major axis is smaller than 10 nm, the coating on the porous membrane tends to be insufficient, and if it is larger than 100 nm, the ion transmittance is too large and it tends to be easily peeled off.

The heating step can be 130 ° C. or higher. The heating temperature is limited to the base material, but if it is 130 ° C. or higher, the bond between the alumina hydrates becomes strong and it becomes difficult to peel off. It is preferably 150 ° C. or higher, more preferably 200 ° C. or higher. The upper limit of the heating temperature can be 300 ° C. If it exceeds 300 ° C., dehydration proceeds too much and the film tends to become brittle.

After the step of immersing the porous membrane in an acidic aqueous solution (BL14), a step of immersing the porous membrane in an aqueous solution of sodium chloride having a concentration of 3% by weight or more and then drying it can be further provided.

By impregnating the porous diaphragm containing a fluorine atom coated with the hydrophilic alumina hydrate in BL14 with sodium chloride, the start-up during the electrolytic operation can be accelerated.

If the concentration is less than 3% by weight, the amount of sodium chloride remaining on the film is small, and the start-up of the device tends to be delayed. More preferably, it is 10% by weight or more, more preferably 15% by weight or more, but if it exceeds 20% by weight, sodium chloride attached to the surface of the porous diaphragm tends to be easily peeled off, and handling tends to be difficult.

The film thickness on the surface of the alumina hydrate coating layer can be 0.1 to 10 μm. If it is smaller than 0.1 μm, the effect on ion permeability tends to be small, and if it is larger than 10 μm, the film tends to peel off easily. It is more preferably 1 to 8 μm, still more preferably 2 to 6 μm.

The film thickness of the porous diaphragm can be 10 to 200 μm. If the film thickness is thinner than 10 μm, the mechanical strength of the film is weakened and the film tends to break easily. If it is thicker than 200 μm, the ion permeability tends to decrease and the electrolysis efficiency tends to decrease. The film thickness is preferably 30 to 150 μm, more preferably 40 to 120 μm.

(Second Embodiment)
FIG. 2 shows a schematic view showing an example of the configuration of the electrode unit used in the embodiment.

As shown in the figure, the electrode unit 20 according to the embodiment has a porous electrode substrate 21 having a porous structure including a plurality of openings and through holes, and a counter electrode 22, and a porous diaphragm 23 arranged between them. Have. A diaphragm 24 on the counter electrode 22 side and an electrolyte holding portion 25 can be further provided.

FIG. 3 shows an example of a method for manufacturing the electrode unit according to the second embodiment.

As shown in the figure, the method for manufacturing the electrode unit according to the second embodiment includes a step of hydrophilizing a porous film containing a fluorine atom coated with alumina hydrate to form a porous diaphragm (BL31). In a state where the porous diaphragm contains water, the porous electrode substrate is arranged between a porous electrode substrate having a plurality of through holes and a counter electrode, and an electrode unit is assembled (BL32).

The step of immersing the porous diaphragm containing a fluorine atom coated with alumina hydrate in an acidic aqueous solution to make it hydrophilic is, for example, similar to the method for producing a diaphragm according to the first embodiment, containing a fluorine atom. A step of immersing the porous film in a hydroalcohol-containing dispersion of alumina hydrate particles, a step of removing the porous film from the dispersion, and heating the porous film coated with the dispersion to surface the surface of the porous film with alumina. It includes a step of forming a hydrate layer and a step of immersing the porous film in an acidic aqueous solution. Preferably, after the step of immersing the porous membrane in the acidic aqueous solution, a step of washing the porous membrane to remove the acidic aqueous solution can be further included.

In BL31, the alumina hydrate coating and the porous membrane containing fluorine atoms can be immersed in an acidic aqueous solution to make them hydrophilic to obtain a porous diaphragm.

In BL32, the initial operation start-up time can be shortened by incorporating the hydrophilic porous diaphragm into the electrode unit while containing water.

According to the embodiment, by using a porous diaphragm coated with alumina hydrate and containing a fluorine atom, electrolysis can be performed efficiently and an electrode unit having a long life can be obtained.

As the acidic aqueous solution, 0.1% by weight to 10% by weight of hydrochloric acid, nitric acid, sulfuric acid and the like can be used.

For cleaning the porous membrane, for example, water or saline solution can be used.

As the base material of the porous electrode substrate, titanium, chromium, aluminum, stainless steel, an alloy thereof, or the like can be used. Titanium or stainless steel can be preferably used.

A catalyst layer can be formed on the electrode surface of the porous electrode substrate. When the porous electrode substrate is used as the anode, a noble metal catalyst such as platinum or an oxide catalyst such as iridium oxide can be used as the catalyst. The amount of catalyst applied to the porous electrode substrate per unit area can be different on both sides of the electrode. As a result, side reactions and the like can be suppressed.

The substrate can have a planar roughness of 0.01 μm to 3 μm.

Below 0.01 μm, the parenchymal surface area of the electrode tends to decrease. If it exceeds 3 μm, the stress on the porous film tends to be easily concentrated on the convex portion of the electrode.

The through holes of the electrodes can have a rectangle or circle with rounded ends, an ellipse or a rhombus with rounded corners. If the edges are rounded, the non-uniformity of the load can be reduced in contact with the porous membrane. When increasing the opening area, a rectangle with a rounded end can be used. On the other hand, a circle can be used to reduce the opening area.

A taper or a curved surface that widens the outside can be formed in the opening of the porous electrode substrate. By forming a taper or a curved surface that widens the outside of the opening, the contact angle between the porous diaphragm and the hole becomes obtuse, and the stress concentration on the porous diaphragm tends to be reduced. As for the opening number density, the larger the porous diaphragm side, the better the diffusion of the substance tends to be.

(Third Embodiment)
FIG. 4 shows a diagram showing an example of a method for manufacturing the electrode unit according to the third embodiment.

In the method for producing an electrode unit according to the third embodiment, a porous electrode substrate containing a fluorine atom, which is coated with alumina hydrate and impregnated with sodium chloride, is provided with a porous electrode substrate having a plurality of through holes. It includes a step of assembling the electrode unit by arranging it between the counter electrode and the electrode unit (BL41), a step of assembling the electrolyzed water generator by incorporating the electrode unit (BL42), and a step of performing a preliminary operation of the electrode unit (BL43).

The method for forming a porous diaphragm coated with the alumina hydrate particles used in the embodiment and containing a fluorine atom containing sodium chloride is, for example, the same as the method for producing a diaphragm according to the first embodiment. In addition, a step of immersing the porous membrane containing a fluorine atom in a hydrous alcohol dispersion of alumina hydrate particles, a step of removing the porous membrane from the dispersion, and heating the porous membrane coated with the dispersion. , A step of forming an alumina hydrate layer on the surface of the porous membrane, a step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution to make it hydrophilic, and further making the porous membrane hydrophilic. It includes a step of immersing the membrane in an aqueous solution of sodium chloride having a concentration of 3% by weight or more and drying it.

In BL41, a porous diaphragm having a sodium chloride and alumina hydrate coating on the electrode unit and containing a fluorine atom can be incorporated into the electrode unit.

Further, in BL42, a porous diaphragm having a coating of sodium chloride and alumina hydrate and containing a fluorine atom can be incorporated into an electrolyzed water generator.

Further, in BL43, by performing the preliminary operation of the electrode unit, the electrolyte can be present in the porous diaphragm, and the start of operation from the next time can be accelerated. Further, the electrode unit can be removed and incorporated into another electrolyzed water generator, and in this case as well, a long-time preliminary operation is not required.

As described above, according to the embodiment, electrolysis can be efficiently performed, and an electrode unit having a long life can be obtained.

FIG. 5 is a cross-sectional view schematically showing an example of the configuration of an electrolyzed water generator to which the diaphragm according to the first embodiment and the electrode units according to the second embodiment and the third embodiment can be applied.

The electrolyzed water generator 50 includes a three-chamber type electrolytic cell 508 and an electrode unit 507. The electrolytic cell 508 is formed in a flat rectangular box shape, and the inside thereof is partitioned by a partition wall 509 and an electrode unit 507 into three chambers, an anode chamber 510, a cathode chamber 511, and an intermediate chamber 506 formed between the electrodes. Has been done.

The electrode unit 507 includes a first electrode 503 located in the anode chamber 510, a second electrode (counter electrode) 504 located in the cathode chamber 511 and having a plurality of predetermined through holes, and a first electrode 503. It has a first porous diaphragm (electrolyte film) 501 on the surface on the two electrode side. A second porous diaphragm 502 can be provided on the surface of the second electrode 504 on the side of the first electrode. The first electrode 503 and the second electrode 504 face each other in parallel with a gap, and form an intermediate chamber (electrolyte solution chamber) 506 for holding the electrolytic solution between the porous diaphragms 501 and 502. .. A holding body (not shown) for holding the electrolytic solution may be provided in the intermediate chamber 506. The first electrode 503 and the second electrode 504 may be connected to each other by a plurality of insulating bridges (not shown).

The electrolyzed water generator 50 includes a power supply 514 for applying a voltage to the first and second electrodes 503 and 504 of the electrode unit 507, and a control device 513 for controlling the power supply 514. An ammeter 516 and a voltmeter 515 can be provided between the power supply 514 and the first and second electrodes 503 and 504. The ammeter 516 and the voltmeter 515 can be connected to the control device 513.

A liquid flow path can be provided in the anode chamber 510 and the cathode chamber 511. From the line L1 for introducing the electrolyte solution containing chloride ions into the intermediate chamber 506, the electrolyte solution tank 517 connected to the line L1, the line L3 for supplying water from the water supply source to the anode chamber 510 and the cathode chamber 511, and the anode chamber 510. A line L4 for taking out acidic electrolyzed water and a line L5 for taking out alkaline electrolyzed water from the cathode chamber 511 can be further provided. Further, a line L2 for recovering the excess electrolyte solution containing chloride ions from the intermediate chamber 506 and circulating the excess electrolyte solution in the electrolyte solution tank 517 may be provided, or the electrolyte solution containing chloride ions may be provided instead of the line L2. A line can be provided to discharge the water. As a water quality sensor, a conductivity sensor 518 can be attached to the line L4 for taking out acidic electrolyzed water, and a pH sensor 519 can be attached to the line L5 for taking out alkaline electrolyzed water.

As the first porous diaphragm (electrolyte membrane) 501, the porous diaphragm according to the first embodiment can be used. Alternatively, as the electrode unit 507, the electrode unit according to the second or third embodiment can be used.

(Example 1)
A diaphragm similar to the diaphragm 20 shown in FIG. 2 is produced.

First, a polyvinylidene fluoride porous membrane having a film thickness of 100 μm and an average pore diameter of 200 nm is prepared. Using alumina hydrate particles (pseudo-boehmite) having a particle size of 10 to 50 nm (average particle size 20 nm) and having the surface hydrophobicized with a silane coupling agent, a 10% by weight hydrous ethanol dispersion (ethanol 95%). ) Is prepared. After immersing the porous membrane in the obtained dispersion, it is taken out and heated at 130 ° C. for 5 minutes in the air.

Next, it is immersed in boiling water in the air for 5 minutes, then taken out and dried in the air at 100 ° C.

Next, the mixture is immersed in 1% by weight hydrochloric acid for 10 minutes and then washed with water to prepare a hydrophilic porous diaphragm having an alumina hydrate layer formed on the surface.

(Example 2)
An electrode unit similar to the electrode unit shown in FIG. 2 is manufactured.

The electrode base material is made of flat titanium having a diameter of 0.5 mm, and holes having a diameter of 2 mm are punched in a staggered manner at a pitch of 3 mm. This electrode is treated in a 10 wt% oxalic acid aqueous solution at 80 ° C. for 1 hour.

After iridium chloride _(IrCl 3 · _nH 2 O) in 1-butanol, the catalyst solution Ir concentration was adjusted added to a 0.25M, it was applied to the surface of the small opening of the electrode substrate, drying and baking do. In this case, drying is carried out at 80 ° C. for 10 minutes, and firing is carried out at 450 ° C. for 10 minutes. An electrode base material prepared by repeating coating, drying and firing of a catalyst solution 5 times to prepare an iridium oxide catalyst is cut into a reaction electrode area of 3 cm × 4 cm and used as a porous electrode substrate (anode).

A counter electrode (cathode) is produced in the same manner as the porous electrode substrate except that platinum is sputtered instead of applying the iridium oxide. Nafion (registered trademark) 117, which is an ion exchange membrane, is used as the porous membrane on the counter electrode side.

In a state where both the porous diaphragm and the Nafion 117 membrane are moistened as in Example 1, a porous polystyrene having a thickness of 5 mm is used as a structure for holding both electrodes and the electrolytic solution, and the two porous membranes and these are silicone-sealed. The electrode unit 507 (20) is formed by stacking them with an agent and a screw.

Using this electrode unit 507, the electrolyzer 50 shown in FIG. 5 is manufactured.

An anode chamber 510 and a cathode chamber 511 made of vinyl chloride having a straight flow path formed therein, and a container 517 for supplying saturated saline to porous polystyrene are connected to the electrode unit 507. A control device 513, a power supply 514, a voltmeter 515, and a current meter 516 are installed, and a pipe L3 for supplying tap water to the anode chamber 510 and the cathode chamber 511, a pump (not shown), and a saturated saline solution are circulated and supplied to the porous polystyrene. A saturated saline reservoir 517, a pipe L1, and a pump (not shown) are installed.

Using this electrolyzer 50, electrolysis is performed at a voltage of 8 V before the electrode unit dries, and hypochlorous acid water is produced on the anode side and sodium hydroxide water is produced on the cathode side. The initial efficiency of electrolysis is 84%. The amount of sodium ions mixed in the hypochlorite water is about 80 ppm. The operation is stopped, the liquid in the electrolyzer 50 is drained, and the mixture is dried for one week. After that, when the operation is performed again, the efficiency becomes 85% within 10 minutes, and the efficiency is stable at 82% even after 1000 hours of continuous operation.

(Example 3)
A hydrous ethanol dispersion of alumina hydrate particles (pseudo-boehmite) whose surface is hydrophobicized with a silane coupling agent as in Example 1 using a polytetrafluoroethylene porous membrane having a film thickness of 60 μm and an average pore size of 100 nm. After immersing in, take out and heat in air at 250 ° C. for 5 minutes.

Next, it is immersed in boiling water in the air for 5 minutes, then taken out and dried in the air at 100 ° C.

Next, the mixture is immersed in 5% by weight hydrochloric acid for 20 minutes and then washed with water to prepare a hydrophilic porous diaphragm having an alumina hydrate layer formed on the surface.

An electrolyzer is produced in the same manner as in Example 2.

Using this electrolyzer, electrolysis is performed at a voltage of 8 V before the electrode unit dries, and hypochlorous acid water is produced on the anode side and sodium hydroxide water is produced on the cathode side.

The initial efficiency of electrolysis is 80%. The amount of sodium ions mixed in the hypochlorite water is about 50 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 80% within 10 minutes, and the efficiency is stable at 79% even after 1000 hours of continuous operation.

(Example 4)
The same porous diaphragm as in Example 1 is washed with water, immersed in a 15 wt% sodium chloride aqueous solution without drying, taken out into the atmosphere, and dried as it is to contain sodium chloride on the surface and inside the pores. To make two.

The electrode is produced in the same manner as in Example 2. As a structure for holding both electrodes and the electrolytic solution, porous polystyrene with a thickness of 5 mm is used, two porous membranes are placed on both sides of the porous polystyrene in a dry state, and the electrode unit is overlapped with a silicone sealant and a screw. And.

An electrolyzer is produced in the same manner as in Example 2 except that the electrode unit in a dry state is used. Pre-electrolysis of the electrode unit is performed at a voltage of 8 V, and the current gradually increases and becomes steady in about 30 minutes. Hypochlorite water is produced on the anode side, and sodium hydroxide water is produced on the cathode side.

The initial efficiency of electrolysis is 78%. The amount of sodium ions mixed in the hypochlorite water is about 80 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 79% within 10 minutes, and the efficiency is stable at 78% even after 1000 hours of continuous operation.

(Example 5)
A polyvinylidene fluoride porous membrane having a film thickness of 100 μm and an average pore diameter of 300 nm is prepared. A 15 wt% dispersion is prepared with a 30 wt% aqueous ethanol solution using alumina hydrate fine particles (pseudo-boehmite) (particle size 50 to 100 nm). The porous membrane is immersed in the obtained dispersion, taken out into the air, and heated at 130 ° C. for 5 minutes in the air. This is repeated twice.

Next, it is immersed in boiling water in the air for 5 minutes, then taken out and dried in the air at 100 ° C.

Next, the mixture is immersed in 1 wt% hydrochloric acid for 10 minutes and then washed with water to prepare a hydrophilic porous diaphragm having an alumina hydrate layer formed on the surface.

An electrolyzer is produced in the same manner as in Example 2.

Using this electrolyzer, electrolysis is performed at a voltage of 8 V before the electrode unit dries to produce hypochlorous acid water on the anode side and sodium hydroxide water on the cathode side.

The initial efficiency of electrolysis is 85%. The amount of sodium ions mixed in the hypochlorite water is about 100 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 84% within 10 minutes, and the efficiency is stable at 84% even after 1000 hours of continuous operation.

(Example 6)
A polyvinylidene fluoride porous membrane having a film thickness of 50 μm and an average pore diameter of 80 nm is prepared. A 10 wt% dispersion is prepared with a 30 wt% aqueous ethanol solution using alumina hydrate fine particles (pseudo-boehmite) (particle size 10 to 30 nm). Take out into the air and heat in the air at 130 ° C. for 5 minutes. This is repeated twice.

Next, it is immersed in boiling water in the air for 5 minutes, then taken out and dried in the air at 100 ° C.

Next, the mixture is immersed in 1 wt% hydrochloric acid for 10 minutes and then washed with water to prepare a hydrophilic porous diaphragm having an alumina hydrate layer formed on the surface.

An electrolyzer is produced in the same manner as in Example 2.

Using this electrolyzer, electrolysis is performed at a voltage of 8 V before the electrode unit dries, and hypochlorous acid water is produced on the anode side and sodium hydroxide water is produced on the cathode side.

The initial efficiency of electrolysis is 75%. The amount of sodium ions mixed in the hypochlorite water is about 10 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 75% within 10 minutes, and the efficiency is stable at 73% even after 1000 hours of continuous operation.

(Example 7)
Instead of immersing in boiling water for 5 minutes in the air, a porous diaphragm is prepared in the same manner as in Example 1 except that it is exposed to steam at 130 ° C. for 10 minutes.

An electrolyzer is produced in the same manner as in Example 2.

Using this electrolyzer, electrolysis is performed at a voltage of 8 V before the electrode unit dries, and hypochlorous acid water is produced on the anode side and sodium hydroxide water is produced on the cathode side.

The initial efficiency of electrolysis is 83%. The amount of sodium ions mixed in the hypochlorite water is about 80 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 83% within 10 minutes, and the efficiency is stable at 82% even after 1000 hours of continuous operation.

(Example 8)
A porous diaphragm is prepared in the same manner as in Example 1 except that a polyvinylidene difluoride porous membrane having a film thickness of 120 μm and an average pore diameter of 330 nm is used.

An electrolyzer is produced in the same manner as in Example 2.

Using this electrolyzer, electrolysis is performed at a voltage of 8 V before the electrode unit dries, and hypochlorous acid water is produced on the anode side and sodium hydroxide water is produced on the cathode side.

The initial efficiency of electrolysis is 80%. The amount of sodium ions mixed in the hypochlorite water is about 120 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week. After that, when the operation is performed again, the efficiency becomes 80% within 10 minutes, and the efficiency is stable at 81% even after 1000 hours of continuous operation.

(Example 9)
The electrode unit and the electrolyzer are produced in the same manner as in Example 2 except that they are not immersed in boiling water for 5 minutes.

The initial efficiency of electrolysis is 80%. The amount of sodium ions mixed in the hypochlorite water is about 70 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 80% within 10 minutes, and the efficiency is relatively stable at 75% even after 1000 hours of continuous operation.

(Example 10)
The electrode unit and the electrolyzer are manufactured in the same manner as in Example 2 except that the electrode unit and the electrolyzer are immersed in water at 60 ° C. instead of being immersed in boiling water in the air.

The initial efficiency of electrolysis is 81%. The amount of sodium ions mixed in the hypochlorite water is about 80 ppm.

The operation was stopped, the liquid was drained, and the mixture was dried for one week.

After that, when the operation is performed again, the efficiency becomes 80% within 10 minutes, and the efficiency is relatively stable at 76% even after 1000 hours of continuous operation.

(Comparative Example 1)
An electrode unit and an electrolyzer are produced in the same manner as in Example 2 except that the porous polyvinylidene fluoride membrane having an average pore size of 200 nm is not treated with alumina hydrate and is immersed in ethanol and washed with water. The initial electrolysis efficiency is as high as 80%, but sodium ions are mixed in the hypochlorite water at a high concentration of 1000 ppm or more.

(Comparative Example 2)
The electrode unit and the electrolyzer are manufactured in the same manner as in Example 2 except that they are not heated at 130 ° C. in the air. The initial electrolysis efficiency is as high as 83%, but the alumina hydrate is easily exfoliated and the efficiency drops to 50% after 1000 hours of continuous operation.

(Comparative Example 3)
Even if an electrode unit and an electrolyzer are to be manufactured in the same manner as in Example 2 except that the treatment with hydrochloric acid is not performed, it is difficult to moisten the porous diaphragm.

(Comparative Example 4)
When water-dispersed alumina hydrate fine particles containing no alcohol are used, the polytetrafluoroethylene porous membrane is difficult to get wet with the aqueous dispersion, and the inside of the porous membrane cannot be coated with alumina hydrate.

(Comparative Example 5)
Even if an electrode unit and an electrolyzer are to be manufactured in the same manner as in Example 2 except that the treatment with hydrochloric acid is not performed, it is difficult to moisten the porous diaphragm.

(Comparative Example 6)
An electrolyzer is produced in the same manner as in Example 4 except that it is not immersed in a 15 wt% sodium chloride aqueous solution. Preliminary electrolysis is performed at a voltage of 8 V using this electrolyzer, and the current gradually increases, but it takes more than 2 hours to become steady.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
Hereinafter, the inventions described in the claims of the present invention will be added.
[1] A step of immersing a porous film containing a fluorine atom in a hydroalcoholic dispersion of alumina hydrate particles, and
The step of removing the porous membrane from the dispersion and
A step of heating the porous membrane coated with the dispersion liquid to form an alumina hydrate layer on the surface of the porous membrane, and
A method for producing a diaphragm, which comprises a step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution.
[2] The method for producing a diaphragm according to claim 1, wherein the alumina hydrate particles are boehmite or pseudo-boehmite.
[3] The method for producing a diaphragm according to claim 1 or 2, wherein the alumina hydrate particles are coated with a hydrophobic group.
[4] The production of the diaphragm according to any one of claims 1 to 3, further comprising a step of heating the porous membrane with hot water or steam before the step of immersing the porous membrane in an acidic aqueous solution. Method.
[5] The method for producing a diaphragm according to any one of claims 1 to 4, wherein the acidic aqueous solution is 0.1% by weight to 10% by weight of hydrochloric acid.
[6] The method for producing a diaphragm according to any one of claims 1 to 5, wherein the porous membrane is polyvinylidene difluoride or polyvinylidene fluoroethylene.
[7] The method for producing a diaphragm according to any one of claims 1 to 6, wherein the step of taking out the porous membrane is a pulling method.
[8] The method for producing a diaphragm according to any one of claims 1 to 7, wherein the porous membrane has an average pore size of 100 nm to 300 nm.
[9] The method for producing a diaphragm according to any one of claims 1 to 7, wherein the major axis of the primary particles of the alumina hydrate particles is 10 nm to 100 nm.
[10] The method according to any one of claims 1 to 9, wherein the step of heating the porous membrane includes heating at a temperature of 130 ° C. or higher.
[11] The method according to any one of claims 1 to 10, further comprising a step of immersing the porous membrane in an acidic aqueous solution, then immersing the porous membrane in an aqueous solution of sodium chloride having a concentration of 3% by weight or more, and drying the membrane. How to make a diaphragm.
[12] A step of hydrophilizing a porous membrane containing fluorine atoms coated with alumina hydrate to form a porous diaphragm, and
A method for manufacturing an electrode unit, which comprises a step of arranging the porous diaphragm between a porous electrode substrate having a plurality of through holes and a counter electrode in a state of containing water and assembling the electrode unit.
[13] The step of hydrophilizing a porous membrane containing fluorine atoms coated with alumina hydrate to form a porous diaphragm is
A step of immersing a porous film containing fluorine atoms in a hydroalcoholic dispersion of alumina hydrate particles,
The step of removing the porous membrane from the dispersion liquid,
A step of heating the porous membrane coated with the dispersion liquid to form an alumina hydrate layer on the surface of the porous membrane.
The method for manufacturing an electrode unit according to claim 12, further comprising a step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution and a step of washing the porous membrane to remove the acidic aqueous solution. ..
[14] A porous diaphragm containing a fluorine atom coated with alumina hydrate and impregnated with sodium chloride is arranged between a porous electrode substrate having a plurality of through holes and a counter electrode, and an electrode unit is provided. A method for manufacturing an electrode unit, which includes a step of assembling the electrode unit, a step of assembling the electrolyzed water generator by incorporating the electrode unit, and a step of performing a preliminary operation of the electrolyzed water generator.
[15] The formation of a fluorine atom-containing porous diaphragm coated with the alumina hydrate and impregnated with sodium chloride is
A step of immersing a porous film containing fluorine atoms in a hydroalcoholic dispersion of alumina hydrate particles,
The step of removing the porous membrane from the dispersion liquid,
A step of heating the porous membrane coated with the dispersion liquid to form an alumina hydrate layer on the surface of the porous membrane.
A claim including a step of immersing the porous film on which the alumina hydrate layer is formed in an acidic aqueous solution to make it hydrophilic to form a porous diaphragm, and a step of immersing the porous diaphragm in an aqueous sodium chloride solution and drying it. Item 14. The method for manufacturing an electrode unit according to Item 14.

20 ... Electrode unit, 21 ... Porous electrode substrate, 22 ... Counter electrode, 23 ... Porous diaphragm, 24 ... Counter electrode side diaphragm, 25 ... Electrolyte holding means, 50 ... Electrolyte device, 501 ... Porous containing alumina hydrate Membrane diaphragm, 502 ... 2nd porous, 503 ... 1st electrode, 504 ... 2nd electrode, 507 ... electrode unit, 508 ... electrolytic cell, 509 ... partition wall, 510 ... anode chamber, 511 ... cathode chamber, 513 ... Control device, 514 ... power supply, 515 ... voltage meter, 516 ... current meter, 517 ... salt water tank, 518 ... conductivity sensor, 516 ... pH sensor,

Claims (13)

A step of immersing a hydrophobic porous film containing fluorine atoms in a hydroalcohol dispersion of alumina hydrate particles, and
The step of removing the porous membrane from the dispersion and
A step of heating the porous membrane coated with the dispersion liquid to form a hydrophobic alumina hydrate layer on the surface of the porous membrane, and a step of forming the hydrophobic alumina hydrate layer.
A method for producing a diaphragm, which comprises a step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution to make it hydrophilic. The method for producing a diaphragm according to claim 1, wherein the alumina hydrate particles are boehmite or pseudo-boehmite. The method for producing a diaphragm according to claim 1 or 2, wherein the alumina hydrate particles are coated with a hydrophobic group. The method for producing a diaphragm according to any one of claims 1 to 3, further comprising a step of heating the porous membrane with hot water or steam before the step of immersing the porous membrane in an acidic aqueous solution. The method for producing a diaphragm according to any one of claims 1 to 4, wherein the acidic aqueous solution is 0.1% by weight to 10% by weight of hydrochloric acid. The method for producing a diaphragm according to any one of claims 1 to 5, wherein the porous membrane is polyvinylidene difluoride or polyvinylidene fluoroethylene. The method for producing a diaphragm according to any one of claims 1 to 6, wherein the step of taking out the porous membrane is a pulling method. The method for producing a diaphragm according to any one of claims 1 to 7, wherein the porous membrane has an average pore size of 100 nm to 300 nm. The method for producing a diaphragm according to any one of claims 1 to 7, wherein the major axis of the primary particles of the alumina hydrate particles is 10 nm to 100 nm. The production method according to any one of claims 1 to 9, wherein the step of heating the porous membrane includes heating at a temperature of 130 ° C. or higher. The diaphragm according to any one of claims 1 to 10, further comprising a step of immersing the porous membrane in an acidic aqueous solution, followed by a step of immersing the porous membrane in an aqueous solution of sodium chloride having a concentration of 3% by weight or more and drying it. Production method. A step of immersing a hydrophobic porous film containing fluorine atoms in a hydroalcohol dispersion of alumina hydrate particles, and
The step of removing the porous membrane from the dispersion and
A step of heating the porous membrane coated with the dispersion liquid to form a hydrophobic alumina hydrate layer on the surface of the porous membrane, and a step of forming the hydrophobic alumina hydrate layer.
A step of immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution to make it hydrophilic.
A step of washing the porous membrane to remove the acidic aqueous solution to form a porous diaphragm, and
Wherein the porous membrane in a state containing water, and the porous electrode substrate having a plurality of through holes, disposed between the counter electrode, the manufacturing method of an electrode unit and a step of assembling the electrode unit. A step of immersing a hydrophobic porous film containing fluorine atoms in a hydroalcohol dispersion of alumina hydrate particles, and
The step of removing the porous membrane from the dispersion and
A step of heating the porous membrane coated with the dispersion liquid to form a hydrophobic alumina hydrate layer on the surface of the porous membrane, and a step of forming the hydrophobic alumina hydrate layer.
A step of hydrophilized, to form a porous membrane by immersing the porous membrane in which the alumina hydrate layer is formed in an acidic aqueous solution,
A step of forming a fluorine atom-containing porous diaphragm coated with the alumina hydrate and impregnated with sodium chloride by immersing the porous diaphragm in an aqueous solution of sodium chloride and drying it.
A fluorine atom-containing porous diaphragm coated with the alumina hydrate and impregnated with sodium chloride is placed between a porous electrode substrate having a plurality of through holes and a counter electrode to assemble an electrode unit. Process and
The process of assembling the electrolyzed water generator by incorporating the electrode unit and
Method of manufacturing an electrode unit and a step of performing a preliminary operation of the apparatus for producing electrolyzed water.

Images