JP2018154909A - Method for producing diaphragm and method for producing electrode unit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods of producing a diaphragm and en electrode unit with high efficiency and a long life.SOLUTION: A method of producing a diaphragm according to an embodiment comprises: a step of immersing a porous membrane comprising a fluorine atom in an alcohol-containing dispersed liquid containing alumina hydrate particles; a step of taking the porous membrane out to the air; a step of heating; and a step of immersing the porous membrane in an acidic aqueous solution.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a method of manufacturing a diaphragm used for electrolysis and a method of manufacturing an electrode unit using the same.

  As an electrolytic device that generates alkaline ionized water, ozone water, hypochlorous acid water, or the like, an electrolytic device having a three-chamber electrolytic cell is used. The three-chamber type electrolytic cell is divided into three chambers, 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. It is done. In the anode chamber and the cathode chamber, an anode and a cathode having a penetrated porous structure are arranged, respectively.

  In such an electrolyzer, for example, salt solution is flowed in the intermediate chamber, water is flowed in the left and right cathode chambers and the anode chamber, and the salt solution in the intermediate chamber is electrolyzed at the cathode and anode, thereby generating in the anode chamber. Hypochlorous acid water is generated from chlorine gas, and sodium hydroxide water is generated in the cathode chamber. The produced hypochlorous acid water is used as sterilizing / disinfecting water, and sodium hydroxide water is used as washing water.

  In such a three-chamber electrolytic cell, the anion exchange membrane is easily deteriorated by chlorine or hypochlorous acid, so that an overlap or a cut is made between the porous anode prepared by punching or the like and the anion exchange membrane. There was a technology to reduce deterioration due to chlorine by inserting a non-woven fabric. It is also known to arrange a porous film so as not to block a hole in an electrode having a large number of holes.

  However, in the above structure, deterioration of the electrolytic cell is inevitable due to a very long operation.

JP 2012-172199 A JP 2006-322053 A Japanese Patent Application Laid-Open No. 11-1000068

  The problem to be solved by the present invention is to provide a method for producing a highly efficient and long-life diaphragm and a method for producing an electrode unit.

According to the embodiment, the step of immersing the porous film containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles;
Removing the porous membrane from the dispersion;
Heating the porous membrane coated with the dispersion to form an alumina hydrate layer on the surface of the porous membrane;
And a step of immersing the porous membrane in which the alumina hydrate layer is formed in an acidic aqueous solution.

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

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

  In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. In addition, each drawing is a schematic diagram for promoting the embodiment and its understanding, and its shape, dimensions, ratio, etc. are different from the actual device, but these are considered in consideration of the following description and known techniques. The design can be changed as appropriate.

(First embodiment)
FIG. 1 is a flowchart showing a method for manufacturing a diaphragm according to the first embodiment.

As shown in FIG. 1, the method for manufacturing a diaphragm according to the embodiment includes a step (BL11) of immersing a porous membrane containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles, and dispersing the porous membrane. A step of removing from the liquid (BL12), a step of heating the porous membrane coated with the dispersion to form an alumina hydrate layer on the surface of the porous membrane (BL13), and an alumina hydrate layer were formed 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 alumina hydrate particles having hydrophobicity dispersed with hydrous alcohol. A hydrous alcohol dispersion of alumina hydrate particles is easy to handle because it has good dispersibility and is difficult to gel. In BL12, a coating layer of a hydrous alcohol dispersion of hydrophobic alumina hydrate particles is formed on the surface of a hydrophobic porous membrane. In BL13, the alumina hydrate particles in the coating layer are fused to form an alumina hydrate coating layer that hardly peels off. In BL14, the hydrophobic group of the alumina hydrate particles is removed to become hydrophilic and stabilized. A porous membrane containing fluorine atoms coated with alumina hydrate according to the first embodiment is obtained.

  When the method according to the embodiment is used, it becomes possible to easily and uniformly coat a hydrophobic porous membrane with alumina hydrate, and it is easy to make it hydrophilic. Thereby, the permeability | transmittance of a chlorine ion can be improved and permeation | transmission suppression of a sodium ion is possible. For this reason, according to the embodiment, electrolysis can be efficiently performed, and a porous diaphragm can be obtained with a long lifetime.

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

  The hydrous alcohol dispersion used in the embodiment can be obtained, for example, by dispersing 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 pseudoboehmite can be used as the alumina hydrate. In addition, 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 to 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 be determined as the amount of Al ₂ O ₃ by measuring the aluminum content 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 Spectrometry). Next, the moisture that weakly adsorbs a part of the porous membrane under 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 gas chromatograph.

  A step of heating with hot water or steam can be included. When treated with hot water of 70 ° C. or higher, boehmite tends to be the main. More preferably, it is 80 degreeC or more, More preferably, it is 100 degreeC or more. When exceeding 100 degreeC, it can pressurize and can carry out. The boehmite fine particles include pseudo boehmite fine particles. Pseudoboehmite has a higher hydration amount than boehmite and easily becomes boehmite by heating. Heating is preferably 80 ° C. or higher and 300 ° C. or lower, more preferably 120 ° C. or higher, and further preferably 150 ° C. or higher.

  In the method of manufacturing a diaphragm according to the embodiment, the porous film 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 membrane, and the bond with the alumina hydrate coating layer is strengthened and is more difficult to peel off.

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

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

  A pulling-up method can be used as the step of taking out into the air. When the pulling method is used, both surfaces can be coated in the same manner, so that more uniform application is possible.

The average pore diameter of the porous membrane can be from 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. If the major axis is larger than 100 nm, the ion permeability tends to be too large and it tends to peel off.

  The heating step can be performed at 130 ° C. or higher. The heating temperature is limited to the base material, but if it is 130 ° C. or higher, the bonds between the alumina hydrates become strong and are difficult to peel off. Preferably it is 150 degreeC or more, More preferably, it is 200 degreeC or more. The upper limit of the heating temperature can be 300 ° C. When 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 in a sodium chloride aqueous solution having a concentration of 3% by weight or more and then drying can be further provided.

  By impregnating sodium chloride into the porous diaphragm containing fluorine atoms coated with the hydrated alumina hydrate in BL14, the start-up during the electrolysis operation can be accelerated.

  If the concentration is less than 3% by weight, the amount of sodium chloride remaining in the membrane is small, and the start-up of the apparatus tends to be slow. More preferably, it is 10% by weight or more, and further preferably 15% by weight or more. However, when it exceeds 20% by weight, sodium chloride attached to the surface of the porous diaphragm tends to be 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 the ion permeability tends to be reduced, and if it is larger than 10 μm, the film tends to be peeled off. More preferably, it is 1-8 micrometers, More preferably, it is 2-6 micrometers.

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

(Second Embodiment)
In FIG. 2, the schematic showing an example of a structure of the electrode unit used for embodiment is shown.

  As illustrated, the electrode unit 20 according to the embodiment includes 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 disposed therebetween. Have. A diaphragm 24 and an electrolyte holding part 25 on the counter electrode 22 side can be further provided.

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

  As shown in the figure, the electrode unit manufacturing method according to the second embodiment includes a step of hydrophilizing a porous membrane containing fluorine atoms coated with alumina hydrate to form a porous diaphragm (BL31). And a step (BL32) of assembling an electrode unit by disposing the porous diaphragm between a porous electrode substrate having a plurality of through holes and a counter electrode in a state containing moisture.

  The step of hydrophilizing the porous membrane containing fluorine atoms coated with alumina hydrate by immersing it in an acidic aqueous solution contains, for example, fluorine atoms, as in the method for producing a membrane according to the first embodiment. The step of immersing the porous membrane in a hydrous alcohol dispersion of alumina hydrate particles, the step of removing the porous membrane from the dispersion, heating the porous membrane coated with the dispersion, and the surface of the porous membrane with alumina A step of forming a hydrate layer, and a step of immersing the porous membrane in an acidic aqueous solution. Preferably, after the step of immersing the porous membrane in the acidic aqueous solution, the method may further include a step of washing the porous membrane to remove the acidic aqueous solution.

  In BL31, a porous membrane can be obtained by immersing an alumina hydrate coating and a porous membrane containing fluorine atoms in an acidic aqueous solution to make it hydrophilic.

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

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

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

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

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

  A catalyst layer can be formed on the electrode surface of the porous electrode substrate. When a porous electrode substrate is used for the anode, a noble metal catalyst such as platinum or an oxide catalyst such as iridium oxide can be used as the catalyst. It is also possible that the amount per unit area of the catalyst applied to the porous electrode substrate is different on both sides of the electrode. Thereby, a side reaction etc. can be suppressed.

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

  If it is less than 0.01 μm, the substantial surface area of the electrode tends to decrease. If it exceeds 3 μm, stress on the porous film tends to concentrate on the convex portion of the electrode.

  The through hole of the electrode may have a rectangular shape with a round end, a circle, an ellipse, or a rhombus with rounded corners. If the ends are round, the load non-uniformity can be reduced in contact with the porous membrane. When the opening area is increased, a rectangle having a rounded end can be used. On the other hand, a circle can be used to reduce the opening area.

  The opening of the porous electrode substrate can be formed with a taper or curved surface whose outside is widened. By forming a taper or curved surface whose outside is widened in 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 the numerical aperture density is larger on the porous diaphragm side, the material diffusion tends to be better.

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

  A method for producing an electrode unit according to a third embodiment includes a porous diaphragm containing fluorine atoms, coated with alumina hydrate and impregnated with sodium chloride, a porous electrode substrate having a plurality of through holes, It includes a step (BL41) of assembling an electrode unit by arranging it between the counter electrodes, a step of assembling this electrode unit to assemble an electrolyzed water generating device (BL42), and a step of performing a preliminary operation of the electrode unit (BL43).

  The method of forming a porous membrane containing fluorine atoms coated with alumina hydrate particles used in the embodiment and containing sodium chloride is the same as, for example, the manufacturing method of the membrane according to the first embodiment. In addition, a step of immersing a porous film containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles, a step of removing the porous film from the dispersion, and heating the porous film coated with the dispersion Including a step of forming an alumina hydrate layer on the surface of the porous membrane, a step of hydrophilizing the porous membrane formed with the alumina hydrate layer by immersing the porous membrane in an acidic aqueous solution. A step of immersing the membrane in a sodium chloride aqueous solution having a concentration of 3% by weight or more and drying the membrane is included.

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

  In BL42, a porous diaphragm containing sodium chloride and alumina hydrate coating and containing fluorine atoms can be incorporated into the electrolyzed water generating apparatus.

  Furthermore, by performing preliminary operation of the electrode unit at BL43, 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 in another electrolyzed water generating apparatus, and in this case, a long-time preliminary operation is not necessary.

  Thus, 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 illustrating an example of a configuration of an electrolyzed water generating apparatus to which the diaphragm according to the first embodiment and the electrode units according to the second and third embodiments can be applied.

  The electrolyzed water generating apparatus 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 into three chambers, an anode chamber 510, a cathode chamber 511, and an intermediate chamber 506 formed between electrodes by a partition 509 and an electrode unit 507. It has been.

  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. A first porous diaphragm (electrolyte membrane) 501 is provided on the surface of the two electrodes. A second porous diaphragm 502 can be provided on the first electrode side surface of the second electrode 504. The first electrode 503 and the second electrode 504 face each other in parallel with a gap therebetween, and form an intermediate chamber (electrolyte chamber) 506 for holding an electrolyte solution between the porous diaphragms 501 and 502. . A holding body (not shown) that holds 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 bridges (not shown) having insulating properties.

  The electrolyzed water generating device 50 includes a power source 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 source 514. An ammeter 516 and a voltmeter 515 can be provided between the power source 514 and the first and second electrodes 503 and 504. An ammeter 516 and a voltmeter 515 can be connected to the control device 513.

  A liquid channel can be provided in the anode chamber 510 and the cathode chamber 511. From the line L1 for introducing an 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, from the anode chamber 510 A line L4 for taking out the acidic electrolyzed water and a line L5 for taking out the alkaline electrolyzed water from the cathode chamber 511 can be further provided. Further, a line L2 for recovering an excess electrolyte solution containing chloride ions from the intermediate chamber 506 and circulating it to the electrolyte solution tank 517 may be provided. Instead of the line L2, an electrolyte solution containing chloride ions may be provided. A line for discharging can be provided. A conductivity sensor 518 can be attached to the line L4 for taking out the acidic electrolyzed water as a water quality sensor, and a pH sensor 519 can be attached to the line L5 for taking out the alkaline electrolyzed water.

  As the first porous membrane (electrolyte membrane) 501, the porous membrane 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 film having a film thickness of 100 μm and an average pore diameter of 200 nm is prepared. Alumina hydrate particles (pseudo boehmite) having a particle size of 10 to 50 nm (average particle size of 20 nm) and having a surface hydrophobized with a silane coupling agent are used, and a 10% by weight aqueous ethanol dispersion (ethanol 95% ) Is prepared. The porous membrane is immersed in the obtained dispersion, taken out, and heated in air at 130 ° C. for 5 minutes.

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

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

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

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

After applying a catalyst solution prepared by adding 1-butanol to iridium chloride (IrCl ₃ .nH ₂ O) so that the Ir concentration becomes 0.25 M on the surface of the small opening of the electrode substrate, drying and firing do. In this case, drying is performed at 80 ° C. for 10 minutes, and baking is performed at 450 ° C. for 10 minutes. The electrode base material on which the iridium oxide catalyst is produced by repeating the application, drying and firing of the catalyst solution five times is cut into a reaction electrode area of 3 cm × 4 cm, and this is used as a porous electrode substrate (anode).

  A counter electrode (cathode) is prepared 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.

  As a structure for holding both electrodes and the electrolyte solution in a state where both the porous diaphragm and the Nafion 117 membrane similar to those of Example 1 are contained, 5 mm thick porous polystyrene is used, and two porous membranes and these are sealed with silicone. An electrode unit 507 (20) is formed by overlapping with an agent and a screw.

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

  A positive electrode chamber 510 and a negative electrode chamber 511 in which straight channels are formed, and a container 517 for supplying saturated saline to porous polystyrene are connected to the electrode unit 507. A control device 513, a power source 514, a voltmeter 515, and an ammeter 516 are installed, and a saturated salt solution is circulated and supplied to the porous polystyrene and a pipe L3 for supplying tap water to the anode chamber 510 and the cathode chamber 511, a pump (not shown). A saturated saline reservoir 517, a pipe L1, and a pump (not shown) are installed.

  Using the electrolyzer 50, electrolysis is performed at a voltage of 8V before the electrode unit is dried, 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%. Mixing of sodium ions into hypochlorous acid water is about 80 ppm. The operation is stopped, the liquid in the electrolyzer 50 is drained and dried for one week. After that, when the operation is resumed, 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 (pseudoboehmite) using a polytetrafluoroethylene porous membrane having a film thickness of 60 μm and an average pore size of 100 nm and having a surface hydrophobized with a silane coupling agent in the same manner as in Example 1. After being dipped in, it is taken out and heated in the atmosphere at 250 ° C. for 5 minutes.

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

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

  An electrolysis apparatus 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 is dried, 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%. Mixing of sodium ions into hypochlorous acid water is about 50 ppm.

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

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

Example 4
A porous membrane similar to that in Example 1 was washed with water, immersed in a 15% by weight sodium chloride aqueous solution without drying, taken out into the atmosphere, and dried as it was, so that the surface and pores contained sodium chloride inside. Make two.

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

  An electrolysis apparatus is produced in the same manner as in Example 2 except that a dry electrode unit is used. Preliminary 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. 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 78%. Mixing of sodium ions into hypochlorous acid water is about 80 ppm.

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

  After that, when the operation is resumed, 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 thickness of 100 μm and an average pore size of 300 nm is prepared. Using alumina hydrate fine particles (pseudo boehmite) (particle size 50-100 nm), a 15 wt% dispersion is prepared with a 30 wt% water-containing ethanol aqueous solution. This porous film is immersed in the obtained dispersion, taken out into the air, and heated in air at 130 ° C. for 5 minutes. Repeat this twice.

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

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

  An electrolysis apparatus 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 is dried, 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 85%. The mixing of sodium ions into hypochlorous acid water is about 100 ppm.

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

  After that, when the operation is resumed, 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 thickness of 50 μm and an average pore size of 80 nm is prepared. Using alumina fine hydrate particles (pseudo boehmite) (particle size 10-30 nm), a 10 wt% dispersion is prepared with a 30 wt% water-containing ethanol aqueous solution. Remove to atmosphere and heat in air at 130 ° C. for 5 minutes. Repeat this twice.

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

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

  An electrolysis apparatus 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 is dried, 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 mixing of sodium ions into hypochlorous acid water is about 10 ppm.

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

  Thereafter, 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)
A porous diaphragm is prepared in the same manner as in Example 1 except that it is exposed to water vapor at 130 ° C. for 10 minutes instead of being immersed in water boiled in the air for 5 minutes.

  An electrolysis apparatus 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 is dried, 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%. Mixing of sodium ions into hypochlorous acid water is about 80 ppm.

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

  After that, when it is operated 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 produced in the same manner as in Example 1 except that a polyvinylidene difluoride porous membrane having a thickness of 120 μm and an average pore size of 330 nm is used.

  An electrolysis apparatus 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 is dried, 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 mixing of sodium ions into the hypochlorous acid water is about 120 ppm.

  The operation was stopped and the liquid was drained and dried for one week. Thereafter, 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
An electrode unit and an electrolysis device are produced in the same manner as in Example 2 except that it is not immersed in water boiled in the atmosphere for 5 minutes.

  The initial efficiency of electrolysis is 80%. The mixing of sodium ions into hypochlorous acid water is about 70 ppm.

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

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

(Example 10)
An electrode unit and an electrolysis device are produced in the same manner as in Example 2 except that it is immersed in water at 60 ° C. instead of being immersed in water boiled in the atmosphere.

  The initial efficiency of electrolysis is 81%. Mixing of sodium ions into hypochlorous acid water is about 80 ppm.

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

  Thereafter, when the operation is resumed, 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 electrolytic device are produced in the same manner as in Example 2 except that a polyvinylidene fluoride porous membrane having an average pore size of 200 nm is not treated with alumina hydrate but is immersed in ethanol and washed with water. Although the initial electrolysis efficiency is as high as 80%, sodium ions are mixed into hypochlorous acid water at a high concentration of 1000 ppm or more.

(Comparative Example 2)
An electrode unit and an electrolysis device are produced in the same manner as in Example 2 except that heating is not performed at 130 ° C. in the atmosphere. The initial electrolysis efficiency is as high as 83%, but the alumina hydrate tends to peel off, and the efficiency decreases to 50% after 1000 hours of continuous operation.

(Comparative Example 3)
Except for not performing the treatment with hydrochloric acid, even if an electrode unit and an electrolysis apparatus are produced in the same manner as in Example 2, it is difficult to hydrate the porous diaphragm.

(Comparative Example 4)
If water-dispersed alumina hydrate fine particles not containing alcohol are used, the polytetrafluoroethylene porous membrane is difficult to wet with the aqueous dispersion and the inside of the porous membrane cannot be coated with alumina hydrate.

(Comparative Example 5)
Except for not performing the treatment with hydrochloric acid, even if an electrode unit and an electrolysis apparatus are produced in the same manner as in Example 2, it is difficult to hydrate the porous diaphragm.

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

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 20 ... Electrode unit, 21 ... Porous electrode board | substrate, 22 ... Counter electrode, 23 ... Porous diaphragm, 24 ... Diaphragm by the side of a counter electrode, 25 ... Electrolyte holding means, 50 ... Electrolytic apparatus, 501 ... Porous containing alumina hydrate Membrane diaphragm, 502 ... second porous, 503 ... first electrode, 504 ... second electrode, 507 ... electrode unit, 508 ... electrolytic cell, 509 ... partition wall, 510 ... anode chamber, 511 ... cathode chamber, 513 ... Control device, 514 ... power source, 515 ... voltmeter, 516 ... ammeter, 517 ... salt water tank, 518 ... conductivity sensor, 516 ... pH sensor,

Claims (15)

Immersing a porous film containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles;
Removing the porous membrane from the dispersion;
Heating the porous membrane coated with the dispersion to form an alumina hydrate layer on the surface of the porous membrane;
Immersing the porous membrane on which the alumina hydrate layer is formed in an acidic aqueous solution.   The method for producing a diaphragm according to claim 1, wherein the alumina hydrate particles are boehmite or pseudoboehmite.   The manufacturing method of the diaphragm of Claim 1 or 2 with which the said alumina hydrate particle | grain is coat | covered with the 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 wt% to 10 wt% hydrochloric acid.   The method for producing a diaphragm according to any one of claims 1 to 5, wherein the porous film is polyvinylidene difluoride or polyterafluoroethylene.   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 said porous membrane is a manufacturing method of the diaphragm of any one of Claim 1 to 7 which has an average hole diameter of 100 nm to 300 nm.   The method for producing a diaphragm according to any one of claims 1 to 7, wherein a major axis of primary particles of the alumina hydrate particles is 10 nm to 100 nm.   The method according to claim 1, 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 and then immersing the porous membrane in an aqueous sodium chloride solution having a concentration of 3% by weight or more and drying. Production method. Hydrophilizing a porous membrane containing fluorine atoms coated with alumina hydrate to form a porous membrane;
A method of manufacturing an electrode unit, comprising the step of assembling an electrode unit by disposing the porous diaphragm between a porous electrode substrate having a plurality of through holes and a counter electrode in a state containing moisture. The step of hydrophilizing a porous membrane containing fluorine atoms coated with alumina hydrate to form a porous membrane,
Immersing a porous film containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles,
Removing the porous membrane from the dispersion;
Heating the porous membrane coated with the dispersion to form an alumina hydrate layer on the porous membrane surface;
The method for producing an electrode unit according to claim 12, comprising a step of immersing the porous membrane in 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. .   A process of assembling an electrode unit by disposing a porous membrane containing fluorine atoms coated with alumina hydrate and impregnated with sodium chloride between a porous electrode substrate having a plurality of through holes and a counter electrode And a step of assembling the electrolyzed water generating device by incorporating the electrode unit and a step of performing a preliminary operation of the electrolyzed water generating device. Formation of a porous membrane containing fluorine atoms, coated with alumina hydrate and impregnated with sodium chloride,
Immersing a porous film containing fluorine atoms in a hydrous alcohol dispersion of alumina hydrate particles,
Removing the porous membrane from the dispersion;
Heating the porous membrane coated with the dispersion to form an alumina hydrate layer on the porous membrane surface;
A step of immersing the porous membrane formed with the alumina hydrate layer in an acidic aqueous solution to make it hydrophilic to form a porous membrane, and a step of immersing the porous membrane in an aqueous sodium chloride solution and drying it. Item 15. A method for producing an electrode unit according to Item 14.

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