KR20080045620A - Method of reactivating electrode for electrolysis - Google Patents

Abstract

A method of reactivating an electrode for electrolysis with reduced activity is provided to accomplish reactivation of the electrode for electrolysis in an electrode for electrolysis in which a thin film made of a metal or a metal alloy is formed, by vacuum sputtering, on a surface of an electrode substrate made of a valve metal or a valve metal alloy, and in which an electrode catalyst layer is formed to coat a surface of the thin film. A method of reactivating an electrode for electrolysis comprises successively performing an acid treatment step of dipping an electrode for electrolysis of which activity has reduced through electrolysis due to deposition of an electrode surface deposit containing a lead compound on a surface of the electrode for electrolysis into an aqueous solution containing 5 mass% to 30 mass% of nitric acid and 5 mass% to 20 mass% of hydrogen peroxide, and a high-pressure water cleaning step of performing high-pressure water cleaning under a pressure of 50 to 100 MPa to remove the electrode surface deposit containing lead, thereby reactivating the electrode for electrolysis of which activity has reduced. A method of reactivating an electrode for electrolysis comprises successively performing an alkali treatment step of dipping an electrode for electrolysis of which activity has reduced through electrolysis due to deposition of an electrode surface deposit containing a lead compound on a surface of the electrode for electrolysis into 5 mass% to 20 mass% of an aqueous alkali metal hydroxide solution, an acid treatment step of dipping the electrode for electrolysis into an aqueous solution containing 5 mass% to 30 mass% of nitric acid and 5 mass% to 20 mass% of hydrogen peroxide, and a high-pressure water cleaning step of performing high-pressure water cleaning under a pressure of 50 to 100 MPa to remove the electrode surface deposit containing lead and antimony, thereby reactivating the electrode for electrolysis of which activity has reduced.

Description

Reactivation of electrolytic electrode {METHOD OF REACTIVATING ELECTRODE FOR ELECTROLYSIS}

The present invention is due to the deposition of a lead compound or an electrode surface deposit containing a lead compound and antimony oxide on the surface of the electrode for electrolysis, for example, in copper foil production or copper electroplating. The present invention relates to a method of reactivating an electrolytic electrode whose activity is reduced through electrolysis, and in particular, a thin film of metal or metal alloy is formed on the surface of a valve metal or valve metal alloy electrode substrate by vacuum sputtering. The present invention relates to a method for reactivating an electrolytic electrode formed by vacuum sputtering and having an electrode catalyst layer formed thereon to apply a surface of a thin film.

For example, in the production of copper foil or electrolysis of industrial electrolysis such as copper plating, an electrode catalyst layer containing iridium oxide is directly formed to apply the surface of an electrode substrate made of a valve metal or valve metal alloy such as titanium and tantalum. Electrodes have been used so far.

However, in this type of oxygen generating electrode, when used for a predetermined period or more, the interface between a valve metal or valve metal alloy metal substrate such as titanium and tantalum and a metal catalyst layer such as iridium oxide is corroded and floating state. A passive-state layer is formed on the surface of the substrate. Therefore, it was difficult to achieve the reactivation treatment, and it was necessary to shave the substrate surface or to manufacture a new electrode substrate until a new surface was revealed.

On the other hand, a thin film made of a metal such as tantalum or niobium and having a thickness of 0.5 to 3 μm is formed on the surface of an electrode substrate made of a valve metal and a valve metal alloy such as titanium and tantalum by vacuum sputtering such as ion plating, and iridium oxide. When the electrode for electrolytic electrode which contains the electrode catalyst layer is formed and the surface of the thin film is used as an oxygen generating electrode, the interface between the electrode substrate and the catalyst layer was not corroded (see Patent Document 1, for example).

However, even in the electrode for oxygen generation described above, when used for electrolytic production in copper foil production or copper plating, on the surface of the electrode for electrolysis, a compound containing lead sulfate or lead sulfate and antimony oxide as a lead compound contained in the electrolyte is contained. In the case of copper foil manufacture, it deposits, and the compound containing lead oxide or lead oxide and antimony oxide as a lead compound contained in electrolyte is deposited in case of electrolyte copper plating. In electrolysis, lead contained in the electrolyte is deposited as lead oxide as a good conductor, while antimony is deposited as antimony oxide as a bad conductor. In addition, lead oxide, a good conductor, turns into lead sulfate, a poor conductor, at the time of stopping electrolysis. In addition, lead sulfate or lead oxide and antimony oxide, which are lead oxides, each of which is an electrode surface deposit, are separated from the surface of the electrode for electrolysis at the start or stop of electrolysis or during electrolysis. Therefore, the above-described oxygen generating electrode results in an uneven current distribution as the electrode for electrolysis, resulting in incomplete thickness of the foil; It has the disadvantage that it cannot be used continuously for a long time as an electrode for electrolysis.

In such a case, in the above-mentioned oxygen generating electrode, the surface of the electrolytic electrode that has been used for electrolysis is wiped with SCOTCH-BRITE (registered trademark), which is a polishing agent manufactured by Sumitomo 3M Co., Ltd., Lead compounds or electrode surface deposits containing lead compounds and antimony oxide were removed, and the electrolytic electrode was then reactivated.

However, in the above-mentioned oxygen generating electrode, when using it continuously for three months, reactivation of the electrode for electrolysis using the above-mentioned brightening agent was difficult.

Patent Document 1: Japanese Patent No. 2761751

Summary of the Invention

The object of the present invention is to solve the disadvantages of the method of the related art described above, and to deposit lead compounds or electrode surface deposits containing lead compounds and antimony oxides, for example, through electrolysis in industrial electrolysis, such as copper foil production or copper plating. The present invention provides a method for efficiently and easily removing an electrode surface deposit containing a lead compound or lead compound and antimony oxide, such as deposited on the surface of an electrolytic electrode having reduced activity due to In an electrolytic electrode in which an alloy thin film is formed by vacuum sputtering on a surface of a valve metal or valve metal alloy electrode substrate and an electrode catalyst layer is formed to apply the surface of the thin film, thereby reactivating the electrolytic electrode. .

In order to achieve the above object, the first aspect of the present invention provides a 5 mass of an electrolytic electrode having reduced activity through electrolysis due to deposition of an electrode surface deposit containing a lead compound on the surface of the electrolytic electrode. An acid treatment step of immersing in an aqueous solution containing% to 30% by mass of nitric acid and 5% to 20% by mass of hydrogen peroxide; And performing a high pressure water wash under a pressure of 50 to 100 MPa to continuously perform a high pressure water wash step to remove lead-containing electrode surface deposits, thereby reducing activity by two steps of an acid treatment step and a high pressure water wash step. It is to provide a method for reactivating an electrode for electrolysis.

The second aspect of the present invention includes the two steps of the acid treatment step and the high pressure water washing step described above, wherein the electrode surface deposit is an electrode surface deposit containing a lead compound and antimony oxide. To provide.

The third aspect of the present invention comprises the two steps of the acid treatment step and the high pressure water washing step described above, wherein the lead compound is a lead oxide.

A fourth aspect of the present invention is to provide a reactivation method comprising the above two steps of an acid treatment step and a high pressure water washing step, wherein the electrolysis is electrolytic for copper plating.

The fifth aspect of the present invention includes the two steps of the acid treatment step and the high pressure water washing step described above, wherein the electrolytic electrode comprises a valve metal or a valve metal alloy electrode made of a metal or metal alloy thin film. It is an electrolytic electrode formed by vacuum sputtering on the surface of a board | substrate and apply | coating the surface of a thin film with an electrode catalyst layer, The reactivation method characterized by the above-mentioned.

The sixth aspect of the present invention includes the two steps of the acid treatment step and the high pressure water washing step described above, wherein the thin film is one or more metals or alloys thereof selected from the group consisting of titanium, tantalum, niobium, zirconium and hafnium. It is to provide a reactivation method characterized in that the thin film.

A seventh aspect of the present invention is to provide a reactivation method comprising the above two steps of an acid treatment step and a high pressure water washing step, wherein the electrode catalyst layer is an electrode catalyst layer containing iridium oxide.

The eighth aspect of the present invention includes the two steps of the acid treatment step and the high pressure water washing step described above, and further comprising the step of forming an electrode catalyst layer after removing the electrode surface deposits. To provide.

In addition, a ninth aspect of the present invention is a method of reactivating an electrode for electrolysis, wherein the electrode surface deposit containing a lead compound is deposited on the surface of the electrode for electrolysis, and the electrode for electrolysis is reduced in electrolysis. An alkali treatment step of dipping in an aqueous alkali metal hydroxide solution of 5% by mass to 20% by mass; An acid treatment step of immersing in an aqueous solution containing 5% by mass to 30% by mass of nitric acid and 5% by mass to 20% by mass of hydrogen peroxide; And an electrolytic electrode material for reactivating the electrolytic electrode having reduced activity by continuously performing a high pressure water washing under a pressure of 50 to 100 MPa to remove electrode surface deposits containing lead and antimony. Provide an activation method.

A tenth aspect of the present invention includes the above three steps of an alkali treatment step, an acid treatment step and a high pressure water washing step, wherein the electrode surface deposit layer is an electrode surface deposit containing a lead compound and antimony oxide. It is to provide a reactivation method.

According to an eleventh aspect of the present invention, there is provided a reactivation method comprising the above three steps of an alkali treatment step, an acid treatment step and a high pressure water washing step, wherein the lead compound is lead sulfate.

The twelfth aspect of the present invention includes the three steps of the above-described alkali treatment step, acid treatment step and high pressure water washing step, wherein the electrolysis is electrolysis for copper foil production. To provide.

The thirteenth aspect of the present invention includes the above three steps of an alkali treatment step, an acid treatment step, and a high pressure water washing step, wherein the electrolytic electrode includes a metal thin film made of metal or a metal alloy, and a metal made of valve metal or a valve metal alloy. It is an electrolytic electrode formed by vacuum sputtering on the surface of a substrate and produced by applying a thin film to an electrode catalyst layer.

A fourteenth aspect of the present invention includes the three steps of the above-described alkali treatment step, acid treatment step and high pressure water washing step, wherein the thin film is at least one metal selected from the group consisting of titanium, tantalum, niobium, zirconium and hafnium. Or it provides a reactivation method characterized in that the alloy thin film.

A fifteenth aspect of the present invention includes the three steps of the above-described alkali treatment step, acid treatment step and high pressure water washing step, wherein the electrode catalyst layer is an electrode catalyst layer containing iridium oxide. It is.

The sixteenth aspect of the present invention includes the three steps of the above-described alkali treatment step, acid treatment step and high pressure water washing step, further comprising forming an electrode catalyst layer after removing the electrode surface deposits. It is to provide a reactivation method.

According to the present invention, lead hydroxide and antimony oxide can be dissolved and removed by an acid treatment step of an electrode surface deposit containing lead oxide or lead oxide and antimony oxide as a lead compound using an aqueous solution containing nitric acid and hydrogen peroxide. Can be; The lead oxide and antimony oxide may be physically removed by the high pressure water washing step of subjecting the remaining lead oxide and antimony oxide to the high pressure water wash. Further, when the lead compound is lead sulfate, an electrode surface deposit containing lead sulfate or lead sulfate and antimony oxide is converted to lead hydroxide by an alkali treatment step using an aqueous sodium hydroxide solution; Next, by the acid treatment step using an aqueous solution containing nitric acid and hydrogen peroxide, lead hydroxide and antimony oxide can be dissolved and removed; The lead and antimony can be physically removed by a high pressure water washing step that causes the remaining lead and antimony to undergo high pressure washing. Therefore, an electrode surface deposit containing a lead compound or lead compound and antimony oxide can be removed efficiently and easily, thereby facilitating reactivation of the electrode for electrolysis.

Detailed description of the invention

Hereinafter, the present invention will be described in detail.

For example, in electrolysis such as electrolytic for copper plating, electrode surface deposits containing lead oxide or lead oxide and antimony as lead compounds are deposited on the surface of the electrolytic electrode, and the activity of the electrolytic electrode is reduced. In such a case, in the present invention, first, as an acid treatment step, an electrolytic electrode having reduced activity is contained in an aqueous solution containing 5% by mass to 30% by mass of nitric acid and 5% by mass to 20% by mass of hydrogen peroxide. Dipping for 5 to 15 hours, whereby lead hydroxide and antimony oxide are dissolved and removed in an aqueous solution containing nitric acid and hydrogen peroxide. Next, as a high pressure water washing step, the electrolytic electrode undergoes high pressure water washing at a pressure of 50 to 100 MPa to physically remove the remaining lead and antimony compounds, thereby reactivating the electrolytic electrode whose activity is reduced. do.

On the other hand, in electrolysis such as electrolytic for copper foil production, electrode surface deposits containing lead sulfate or lead sulfate and antimony as lead compounds are deposited on the surface of the electrode for electrolysis, thereby reducing the activity of the electrode for electrolysis. In such a case, in the present invention, first, as an alkali treatment step, an electrolytic electrode having reduced activity is immersed in an aqueous solution of 5% by mass to 20% by mass of an alkali metal hydroxide for 1 to 3 hours to contain lead and antimony. Lead sulphate in the electrode surface deposits is converted to lead hydroxide by aqueous sodium hydroxide solution. Next, as an acid treatment step, the electrolytic electrode was immersed in an aqueous solution containing 5% by mass to 30% by mass of nitric acid and 5% by mass to 20% by mass of hydrogen peroxide for 5 to 15 hours, whereby lead hydroxide and antimony oxide were used. Silver is dissolved and removed in an aqueous solution containing nitric acid and hydrogen peroxide. In addition, in the high pressure water washing step, the electrolytic electrode undergoes high pressure water washing under a pressure of 50 to 100 MPa to physically remove the remaining lead and antimony compounds, thereby reactivating the electrolytic electrode having reduced activity.

In the acid treatment step, if the concentration of nitric acid exceeds 30 mass% in an aqueous solution containing nitric acid and hydrogen peroxide, or the concentration of hydrogen peroxide in an aqueous solution containing nitric acid and hydrogen peroxide exceeds 20 mass%, for example, titanium Not only does the substrate of the phosphorus electrolytic electrode start to corrode, but the electrode catalyst layer of the electrolytic electrode may be peeled off. On the other hand, when the concentration of nitric acid is less than 5% by mass or the concentration of hydrogen peroxide is less than 5% by mass, the reaction for dissolving lead hydroxide and antimony oxide is insufficient. For that reason, the concentration of nitric acid in an aqueous solution containing nitric acid and hydrogen peroxide is 5% by mass to 30% by mass; The concentration of hydrogen peroxide in the aqueous solution containing nitric acid and hydrogen peroxide is required to be 5% by mass to 20% by mass. In addition, the time for immersing the electrode for electrolysis in an aqueous solution containing nitric acid and hydrogen peroxide is required to be 5 hours or more, preferably 15 hours or more.

In the alkali treatment step, the alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide. When the concentration of the alkali metal hydroxide in the aqueous solution exceeds 20% by mass, the substrate of the electrolytic electrode, for example, titanium, starts to corrode, and therefore, the concentration of the alkali metal hydroxide in the aqueous solution is required to be 20% by mass or less. On the other hand, when the concentration of the alkali metal hydroxide in the aqueous solution is less than 5% by mass, the reaction for converting lead sulfate of the electrode surface deposit containing lead and antimony into lead hydroxide is not sufficient. Therefore, the concentration of the alkali metal hydroxide in the aqueous solution is required to be 5% by mass to 20% by mass. Further, when the time for immersing the electrolytic metal in the aqueous alkali metal hydroxide solution exceeds 3 hours, for example, the substrate of the electrolytic electrode, which is titanium, begins to corrode, and thus, the electrolytic metal is immersed in the aqueous alkali metal hydroxide solution. The time needs to be 3 hours or less.

In addition, in the high pressure water washing step, in order to physically remove the remaining lead and antimony compounds, the high pressure water washing needs to be performed under a pressure of 50 to 100 MPa. If the pressure for washing the high pressure water is less than 50 MPa, the removal efficiency is low, whereas if it exceeds 100 MPa, a hole is drilled in the substrate of the electrolytic electrode, for example, titanium.

Further, in the present invention, as described above, when the electrode catalyst layer is consumed after removal of the electrode deposit, the electrode catalyst layer is newly formed later by the above-described method.

A metal material is used for the electrode substrate of the electrode for electrolysis, and the material and shape are not particularly limited as long as it has conductivity and appropriate rigidity. Valve metals having good corrosion resistance, for example titanium, tantalum, niobium, and zirconium, or alloys thereof, are suitable. If the surface of an electrode base material is made corrosion-resistant efficiently by the amorphous layer which has corrosion-resistant coating, it is also possible to use the metal which has favorable electroconductivity, such as copper and aluminum, for example. If necessary, surface treatment is appropriately performed on the electrode substrate by physical or chemical pretreatment such as annealing, blasting, or the like, for example, surface cleaning by acid washing.

Next, a metal thin film is formed on the surface of the substrate. The metal which forms a thin film is not specifically limited as long as it has favorable electroconductivity and corrosion resistance, or a favorable adhesiveness with respect to a board | substrate or an electrode catalyst layer. Typical examples of materials are titanium, tantalum, niobium, zirconium, and hafnium, and their alloys, all of which have good corrosion resistance. These materials have particularly good adhesion to valve metal electrode substrates such as titanium, for example.

As a method of forming such a thin film on an electrode substrate, a thin film formation method by vacuum sputtering is adopted. According to the vacuum sputtering method, it is easy to obtain a thin film in a grainless amorphous form. In vacuum sputtering, various methods such as direct current sputtering, high frequency sputtering, arc ion plating, ion beam plating, and cluster ion beam methods are applicable. Thin films having desired physical properties can be obtained by appropriately setting conditions such as vacuum degree, temperature of the substrate, composition or purity of the target plate, and deposition rate (power to be applied). The thickness of the surface modifying layer due to the formation of the thin film is usually in the range of 0.1 to 10 mu m, and may be selected from practically useful viewpoints such as corrosion resistance and productivity. Therefore, an electrode substrate whose surface is modified by the formation of a thin film of a grain boundary amorphous layer can generate excellent characteristics for thermal oxidation of the substrate, that is, remarkable characteristics in the growth behavior of the oxide film. The titanium plate produced by degreasing commercially available pure titanium plate (TP2B) and cleaning the surface by acid washing, and each titanium plate produced by forming a thin film coating of pure titanium on the surface by vacuum sputtering, While using a titanium plate as a target, heat treatment was performed in an electric furnace having a uniform temperature distribution in an air atmosphere of 450 ° C. to 600 ° C. for 0 to 5 hours under conditions capable of forming a fine oxide film on titanium. As a result, compared to the original titanium plate, the later surface modified titanium plate is monotonous in color tone; No color irregularities such as spots were observed; The growth of the oxide film is very homogenous; The difference of the slow growth rate of the oxide film was shown. This effect of suppressing the growth of the oxide film is remarkable when the material composition of the amorphous layer is made of an alloy composition rather than a single metal. The homogenization and suppression effect of the surface modifying layer on thermal oxidation not only reduces the thermal effect in the electrode catalyst layer formation step but also the relaxation effect on electromechanical oxidation in electrolysis as described below, thereby improving the durability of the electrode. Contributes greatly.

Thereafter, the electrode substrate on which the thin film is formed is coated with an electrode catalyst layer to provide an electrode for electrolysis. As the electrode catalyst layer, various known materials can be applied according to the use, and the electrode catalyst layer is not particularly limited. For oxygen generating reactions that require durability, materials containing platinum group metal oxides such as iridium oxide are suitable. As a method for applying the electrode catalyst layer, various methods are known and can be appropriately applied. The thermal decomposition method is a common method. Salts of raw materials of the electrode coating layer component metals, such as chlorides, nitrides, alkoxides and resonates, for example, are dissolved in solvents such as hydrochloric acid, nitric acid, alcohols and organic solvents to form a coating liquid. The coating liquid is applied to the surface of the surface-modified substrate and heat-treated in a backing furnace after drying, for example in an oxidizing atmosphere such as air.

It is also possible to apply a thick film method, or a CVD method, in which a metal oxide is prepared in advance and an appropriate organic binder and organic solvent are added to form a paste and then printed and baked on the electrode substrate. In addition, the metal oxide layer may be provided as an intermediate layer by a method of thermally treating the surface-modified substrate described above before application to the electrode catalyst layer to form a very thin high temperature oxide layer as an intermediate layer, thermal decomposition, CVD method, or the like on the surface thereof. have. By this intermediate layer, the adhesive strength of the electrode catalyst layer is increased, and a protective effect against thermal or electrical oxidation of the substrate can be expected, and accordingly, the durability of the electrode for electrolysis as well as the essential effect of the above-mentioned by the thin film on the substrate can be expected. It is also possible to obtain further improvements of.

Example

Next, the present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto.

Example 1

The surface of the JIS grade 1 titanium plate was subjected to a dry blast treatment using an iron grid (# 120) and an acid wash treatment for 10 minutes in a 20% sulfuric acid aqueous solution (at 105 DEG C), thereby washing the electrode substrate. It was. The cleaned electrode substrate was set in an arc ion plating apparatus and subjected to sputtering application with pure titanium material. Application conditions are as follows.

Target: JIS Grade 1 titanium disc (back side is water-cooled)

Vacuum degree: 1.0 × 10 ^-2 Torr (argon gas is introduced and removed)

Applied Power: 500W (3.0kV)

Substrate temperature: 150 ℃ (at sputtering)

Time: 35 minutes

Coating thickness: 2 microns (calculated by weight increase)

As a result of the X-ray diffraction analysis performed after the sputtering application, a sharp crystal peak located in the substrate bulk and a wide pattern located in the sputtering application were observed, and the application was amorphous.

Next, iridium tetrachloride and tantalum pentachloride are dissolved in 35% hydrochloric acid to form a coating liquid, and then brush applied to the substrate on which the above-mentioned sputtering coating process is completed. After drying, the substrate is subjected to thermal decomposition application (for 20 minutes at 550 ° C.) in an air circulation electric furnace to form an electrode catalyst layer made of a solid solution of iridium oxide and tantalum oxide. The amount of the above-described coating liquid was set so as to be substantially 1.0 g / m ² with respect to the iridium metal with respect to the coating thickness of single brush application.

The application from baking to baking was repeated 12 times to produce an electrode for electrolysis. The electrolytic electrode thus produced was subjected to electrolysis under the following conditions.

Current density: 125 A / dm ²

Electrolytic Temperature: 60 ℃

Electrolyte: Simulated liquid for copper plating containing lead chloride

The electrolytic electrode used became inoperative after 6 months. Next, this electrolytic electrode went through the reactivation process under the following conditions.

An electrode surface deposit containing lead oxide was formed on the surface of the electrode. The electrolytic electrode having an electrode surface deposit containing lead oxide was immersed in an aqueous solution of 5 mass% nitric acid and 5 mass% hydrogen peroxide for 15 hours as an acid treatment step, and then as a high pressure water washing step, High pressure water washing under 50 MPa pressure. As a result, electrode surface deposits containing lead oxide deposited on the surface of the electrolytic electrode could be completely removed.

Then, the quantity of the iridium oxide of the electrode catalyst layer of the electrode for electrolysis was measured now. Application was added when the amount of IrO ₂ was less than 5 g / m ² , whereas when the amount of iridium oxide was 5 g / m ² or more, the electrolytic electrode was reused as it is.

Electrolysis was performed under the above-described electrolysis conditions. As a result, the electrolytic electrode could be used over six months, like a new article.

Example 2

In Example 1 described above, a simulation solution for copper plating containing lead chloride and antimony oxide was used as the electrolyte, and the same implementation was carried out under the same conditions as in Example 1. As a result, the same result as in Example 1 was obtained.

Example 3

The surface of the JIS grade 1 titanium plate was subjected to a dry blast treatment using an iron grid (# 120) and an acid wash treatment (at 105 ° C.) in a 20% sulfuric acid solution for 10 minutes, thereby cleaning the electrode substrate. It was done. The cleaned electrode substrate was set in an arc ion plating apparatus and subjected to sputtering application with pure titanium material. Application conditions are as follows.

Target: JIS Class 1 Titanium Disc (back side is water cooled)

Vacuum degree: 1.0 × 10 ^-2 Torr (argon gas is introduced and removed)

Applied Power: 500W (3.0kV)

Substrate temperature: 150 ℃ (at sputtering)

Time: 35 minutes

Coating thickness: 2 microns (calculated by weight increase)

As a result of the X-ray diffraction analysis performed after the sputtering application, a sharp crystal peak located in the substrate bulk and a wide pattern located in the sputtering application were observed, and the application was amorphous.

Next, iridium tetrachloride and tantalum pentachloride are dissolved in 35% hydrochloric acid to form a coating liquid, and then brush applied to the substrate on which the above-mentioned sputtering coating process is completed. After drying, the substrate is subjected to pyrolysis application (for 20 minutes at 550 ° C.) in an air circulation electric furnace to form an electrode catalyst layer made of a solid solution of iridium oxide and tantalum oxide. The amount of the above-described coating liquid was set so as to be substantially 1.0 g / m ² with respect to the iridium metal with respect to the coating thickness of single brush application.

The application from baking to baking was repeated 12 times to produce an electrode for electrolysis. The electrolytic electrode thus produced was subjected to electrolysis under the following conditions.

Current density: 125 A / dm ²

Electrolytic Temperature: 60 ℃

Electrolyte: Simulation solution for the production of copper foil containing lead sulfate

The electrolytic electrode used became inoperative after 6 months. Next, this electrolytic electrode went through the reactivation process under the following conditions.

As an alkali treatment step, an electrolytic electrode having an electrode surface deposit containing lead sulfate and antimony oxide on the surface was immersed in a 5 mass% sodium hydroxide aqueous solution for 3 hours, and as an acid treatment step, 5 mass% nitric acid and 5 It was immersed in an aqueous solution of mass% hydrogen peroxide for 15 hours, and then subjected to high pressure water washing under a pressure of 50 MPa as a high pressure water washing step. As a result, electrode surface deposits containing lead sulfate deposited on the electrolytic electrode could be completely removed.

Then, the quantity of the iridium oxide of the electrode catalyst layer of the electrode for electrolysis was measured now. Application was added when the amount of IrO ₂ was less than 5 g / m ² , whereas when the amount of iridium oxide was 5 g / m ² or more, the electrolytic electrode was reused as it is. Electrolysis was performed under the above-described electrolysis conditions. As a result, the electrolytic electrode could be used over six months, like a new article.

Example 4

An electrode as prepared in Example 3 was used at an electrolytic temperature of 55 ° C. and a current density of 80 A / dm ² . As a result, it became impossible to manufacture the foil after 10 months passed.

The electrode was immersed in 10 mass% sodium hydroxide aqueous solution for 1 hour, immersed in 10 mass% nitric acid and 10 mass% hydrogen peroxide aqueous solution for 15 hours, and then washed with high pressure water under pressure of 70 MPa. As a result, electrode surface deposits containing lead and antimony deposited on the surface of the electrolytic electrode could be completely removed, and the electrolytic electrode could be used for an additional 10 months.

Example 5

An electrode as prepared in Example 3 was used at an electrolytic temperature of 45 ° C. and a current density of 50 A / dm ² . As a result, it became impossible to manufacture the foil after 12 months.

The electrode was immersed in 20 mass% aqueous sodium hydroxide solution for 2 hours, immersed in 30 mass% nitric acid and 20 mass% hydrogen peroxide aqueous solution for 15 hours, and then washed under high pressure water under pressure of 100 MPa. As a result, electrode surface deposits containing lead and antimony deposited on the surface of the electrolytic electrode could be completely removed, and the electrolytic electrode could be used for an additional 12 months.

Example 6

In Example 3 mentioned above, the simulation liquid for copper foil containing lead sulfate and antimony oxide was used as electrolyte, and the same implementation was carried out under the same conditions as in Example 3. As a result, the same result as in Example 3 was obtained.

Comparative Example 1

On the other hand, when only nitric acid or hydrogen peroxide was used in place of an aqueous solution containing nitric acid and hydrogen peroxide, the efficiency of dissolution and removal reaction of the deposit was not good. Also, when sulfuric acid was used instead of nitric acid, the reaction efficiency was similarly very poor, and the electrolytic electrode could not be used. In addition, when hydrochloric acid was used instead of nitric acid, there was a disadvantage that the working environment worsened.

INDUSTRIAL APPLICABILITY The present invention is applicable to various reactivation methods of an electrode for electrolysis not only for the production of electrolytic copper powder or electrolytic copper foil or for copper plating but also for other uses.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope thereof.

This application is based on Japanese Patent Application Nos. 2006-313252 (filed November 20, 2006) and 2007-230379 (filed September 5, 2007), the contents of which are incorporated herein by reference. .

Claims (16)

As a method of reactivating the electrode for electrolysis, Electrolytic electrode having reduced activity through electrolysis due to the deposition of electrode surface deposits containing lead compounds on the surface of the electrolytic electrode, 5% by mass to 30% by mass of nitric acid and 5% by mass to 20% by mass An acid treatment step of immersing in an aqueous solution containing hydrogen peroxide; And A high pressure water washing step of performing high pressure water washing under a pressure of 50 to 100 MPa to remove the electrode surface deposits containing lead. The electrolytic electrode reactivation method which reactivates the electrolytic electrode whose activity was reduced by performing continuously. The method of claim 1, And the electrode surface deposit is an electrode surface deposit containing a lead compound and an antimony oxide. The method of claim 1, The lead compound is a lead electrode reactivation method characterized in that the lead oxide. The method of claim 1, The electrolytic electrode reactivation method characterized in that the electrolytic for copper plating. The method of claim 1, The electrode for electrolysis is formed by forming a metal or metal alloy thin film by vacuum sputtering on a surface of a valve metal or a valve metal alloy electrode substrate and applying the surface of the thin film to an electrode catalyst layer. Electrolytic electrode reactivation method characterized in that the electrode. The method of claim 5, The thin film is at least one metal selected from the group consisting of titanium, tantalum, niobium, zirconium and hafnium or an alloy thin film made of an alloy thereof. The method of claim 5, And the electrode catalyst layer is an electrode catalyst layer containing iridium oxide. The method of claim 1, Forming an electrode catalyst layer after removing the electrode surface deposits Electrolytic electrode reactivation method comprising a further. As a method of reactivating the electrode for electrolysis, Alkali treatment which immerses the electrode for electrolysis which reduced activity through electrolysis in 5 mass%-20 mass% aqueous alkali metal hydroxide aqueous solution because the electrode surface deposit containing a lead compound deposits on the surface of the said electrode for electrolysis step; An acid treatment step of immersing in an aqueous solution containing 5% by mass to 30% by mass of nitric acid and 5% by mass to 20% by mass of hydrogen peroxide; And High pressure water washing step under pressure of 50 to 100 MPa to remove the electrode surface deposits containing lead and antimony The electrolytic electrode reactivation method which reactivates the said electrolytic electrode whose activity was reduced by performing continuously. The method of claim 9, And the electrode surface deposit is an electrode surface deposit containing a lead compound and an antimony oxide. The method of claim 9, The lead compound is an electrolytic electrode reactivation method, characterized in that lead sulfate. The method of claim 9, The electrolysis is electrolytic electrode reactivation method, characterized in that for electrolytic copper foil production. The method of claim 9, The electrolytic electrode is an electrolytic electrode produced by forming a metal or metal alloy thin film by vacuum sputtering on a surface of a valve metal or valve metal alloy electrode substrate and applying the thin film to an electrode catalyst layer. Electrolytic electrode reactivation method. The method of claim 13, The thin film is at least one metal selected from the group consisting of titanium, tantalum, niobium, zirconium and hafnium or an alloy thin film made of an alloy thereof. The method of claim 13, And the electrode catalyst layer is an electrode catalyst layer containing iridium oxide. The method of claim 9, Forming an electrode catalyst layer after removing the electrode surface deposits Electrolytic electrode reactivation method comprising a further.