JP2018044189A - Electrolysis defatting method and electrolysis defatting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolysis defatting method capable of more surely removing contaminants such as an oil component from a surface of an objection to be cleaned without generating reattachment of removed contaminants to the object to be cleaned and an electrolysis defatting device using the same.SOLUTION: There are adopted an electrolysis defatting method for removing contaminants such as an oil component adhered to an object to be cleaned by using an alkaline electrolytic water, including arranging the object to be cleaned and an anode electrode in an alkaline electrolytic water and energizing them, cathode polarizing the object to be cleaned to form hydrogen bubbles with diameter of 20 nm to 10 μm on a surface of the object to be cleaned, and breaking the hydrogen bubbles in vicinity of the surface of the object to be cleaned to conduct removal of the contaminants adhered to the surface of the object to be cleaned by an impulse wave do to the breakage, the anode electrode has an electrode catalyst layer containing iridium oxide of 20 g/mon a surface thereof, and an electrolysis defatting device for conducting the method.SELECTED DRAWING: Figure 1

Description

  The invention according to the present application relates to an electrolytic degreasing method for removing contaminants attached to the surface of an object to be cleaned, and an electrolytic degreasing apparatus for carrying out the electrolytic degreasing method.

  Generally, when plating or painting treatment is performed on the surface of an industrial part, it is necessary to remove contaminants present on the surface to be treated. To remove the pollutants. Most of the pollutants are oils such as water-soluble oils and non-aqueous oils used in the production process. If these contaminants remain on the surface of industrial parts, it is impossible to form a plating or coating film, or even if a plating or coating film can be formed, Large variations will occur.

  Therefore, degreasing treatment has been conventionally employed as a pretreatment for performing plating treatment or coating treatment on the surface of industrial parts. Degreasing methods include alkali degreasing and electrolytic degreasing. Alkaline degreasing is performed by immersing an object to be treated in an alkaline degreasing solution mainly containing a hydroxide, various alkali compounds such as phosphates, silicates, and carbonates, and a surfactant. Similarly to alkaline degreasing, electrolytic degreasing uses an alkaline degreasing solution to electrolyze the object to be treated, and physically removes dirt by gas generated on the surface. When the object to be treated is a cathode, the surface is physically removed by hydrogen gas generated on the surface, and when the object to be treated is an anode, oxygen gas generated on the surface is used. The dirt on the surface is oxidized and decomposed to remove the dirt.

  For example, there is Patent Document 1 as a prior art employing an electrolytic degreasing method. In Patent Document 1, “a conductive member having foreign matters such as oil, rust, and dirt on its surface is used as a cathode, a metal electrode is used as an anode, and the anode and the cathode are immersed in an electrolytic solution; By applying a voltage between the anode and the cathode and causing a current to flow between the two electrodes to continuously generate bubbles on the surface of the conductive member, and mechanical agitation with the bubbles, And a step of removing the foreign matter from the surface of the conductive member. An electrolytic degreasing method for a conductive member is disclosed.

Japanese Patent Laid-Open No. 10-245700

  However, in Patent Document 1 as described above, the surface of the conductive member is subjected to mechanical stirring and cathode reduction with hydrogen gas generated from the surface of the conductive member serving as a cathode by electrolyzing an electrolytic solution that is an alkaline degreasing solution. Since the foreign matter is to be removed, the foreign matter of the conductive member having complicated fine irregularities on the surface could not be removed. This is because the hydrogen gas generated from the surface of the conductive member when the electrolytic solution containing the alkali compound and the surfactant is electrolyzed is relatively large, and there is a recess smaller than the bubbles on the surface of the conductive member. This is because the bubbles cannot enter the recess.

  Moreover, in patent document 1, since foreign substances, such as the oil component removed from the electroconductive member surface by electrolytic degreasing, are floating in electrolyte solution, when pulling up the electroconductive member from the electrolyte solution, the surface again There is a problem that the separated foreign matter adheres to the tank and the foreign matter is brought into the tank where the next process is performed. Furthermore, the electrolytic solution in which the concentration of the oil or the like is increased has a problem that wastewater treatment becomes complicated.

  From the above, it is possible to remove contaminants such as oil more reliably even if the object to be cleaned has complex fine irregularities on the surface. It has been desired to develop an electrolytic degreasing method and an electrolytic degreasing apparatus that can eliminate the inconvenience of being reattached to an object.

  Therefore, as a result of intensive studies, the inventors have come to the idea of adopting an electrolytic degreasing method and an electrolytic degreasing apparatus as described below.

Electrolytic degreasing method: The electrolytic degreasing method according to the present application is a degreasing method for removing contaminants such as oil adhering to the surface of an object to be cleaned using alkaline electrolyzed water, and the object to be cleaned in alkaline electrolyzed water. The anode to be cleaned is cathode-polarized to form a hydrogen bubble having a diameter of 20 nm to 10 μm on the surface of the object to be cleaned, and a hydrogen bubble near the surface of the object to be cleaned. was destroyed, which performs contaminant removal adhering to the surface of the cleaned object by shock waves (cavitation) accompanying such destruction, the anode ^{electrode, 10g / m 2 ~20g / m} 2 amount on the surface thereof And an electrode catalyst layer containing iridium oxide.

  In the electrolytic degreasing method according to the present application, the alkaline electrolyzed water is preferably an aqueous solution having a pH of 11 to 13 containing potassium carbonate and potassium hydroxide.

  In the electrolytic degreasing method according to the present application, the destruction of the hydrogen bubble near the surface of the object to be cleaned is preferably performed by irradiating the hydrogen bubble with ultrasonic waves in alkaline electrolytic water.

  In the electrolytic degreasing method according to the present application, the superoxide anion generated at the anode electrode being energized and the oil removed from the surface of the object to be cleaned are reacted in the alkaline electrolyzed water, and the oil is converted to carbon. It is preferable to decompose into carbon dioxide.

Electrolytic degreasing apparatus: The electrolytic degreasing apparatus according to the present application is an electrolytic degreasing apparatus for cleaning the surface of an object to be cleaned using the above-described electrolytic degreasing method, and a degreasing tank for storing alkaline electrolyzed water; The anode electrode disposed in the degreasing tank and the object to be cleaned are immersed in the alkaline electrolyzed water, and the object to be cleaned is cathode-polarized to have a diameter of 20 nm on the surface of the object to be cleaned. A circulating filtration means comprising: an energization means for forming a hydrogen bubble of 10 μm; a hydrogen bubble destruction means for destroying a hydrogen bubble near the surface of the object to be cleaned; and a circulating filtration means for the alkaline electrolyzed water. Is characterized in that the alkaline electrolyzed water overflowed from the degreasing tank is filtered by a filtering means and then returned to the lower part of the degreasing tank.

  In the electrolytic degreasing apparatus according to the present application, it is preferable to use an iridium oxide electrode as the anode electrode.

  In the electrolytic degreasing apparatus according to the present application, it is preferable that at least an inner surface of the degreasing tank is made of a material that can reflect ultrasonic waves, and the anode electrode includes a communication portion that can transmit ultrasonic waves.

  Further, in the electrolytic degreasing apparatus according to the present application, the hydrogen bubble destruction means is an ultrasonic irradiation means for irradiating ultrasonic waves in alkaline electrolytic water against hydrogen bubbles generated on the surface of the object to be cleaned. preferable.

  By using the electrolytic degreasing method and the electrolytic degreasing apparatus according to the present application, it is possible to effectively remove the contaminants attached to the surface of the object to be cleaned even if the object has a complicated and fine uneven surface shape. It becomes possible. Moreover, since the oil removed from the surface of the object to be cleaned can be decomposed into carbon and carbon dioxide in alkaline electrolyzed water, the removed oil does not reattach to the surface of the object to be cleaned. Therefore, according to the electrolytic degreasing method and the electrolytic degreasing apparatus according to the present application, it is possible to obtain a cleaning effect that is significantly superior to the conventional degreasing treatment method and the degreasing treatment apparatus.

It is a schematic explanatory drawing in one Embodiment of an electrolytic degreasing apparatus. It is a schematic explanatory drawing in another one Embodiment of an electrolytic degreasing apparatus.

  Hereinafter, the embodiment of the present invention will be described in the order of “form of electrolytic degreasing method” and “form of electrolytic degreasing apparatus”.

<About the electrolytic degreasing method according to the present application>
The electrolytic degreasing method according to the present application is to remove contaminants such as oil adhering to the surface of an object to be cleaned using alkaline electrolyzed water. Further, in the present invention, the object to be cleaned and the anode electrode are placed in the alkaline electrolyzed water and energized, so that the object to be cleaned is cathodically polarized and hydrogen having a diameter of 20 nm to 10 μm is formed on the surface of the object to be cleaned. A bubble is formed, hydrogen bubbles are destroyed in the vicinity of the surface of the object to be cleaned, and contaminants attached to the surface of the object to be cleaned are removed by a shock wave accompanying the destruction. Then, electrolytic degreasing method according to the present application is characterized by having an electrode catalyst layer containing iridium oxide in an amount surface of 10g ^/ m ² ~20g / m 2 of the anode electrode. Hereinafter, the electrolytic degreasing method according to the present application will be specifically described.

Alkaline electrolyzed water: “Alkaline electrolyzed water” used in the present invention is generally an aqueous solution exhibiting alkalinity obtained by subjecting water to which an electrolyte is added to electrolysis with a predetermined direct current in a membrane-type electrolytic layer. Considering the formation of hydrogen micro-nano bubbles on the surface of the object to be cleaned when the object to be cleaned and the anode electrode are placed in alkaline electrolyzed water and energized, the alkaline electrolyzed water is composed of potassium carbonate and hydroxide. It is preferable that potassium is added.

  Furthermore, considering that the oil removed from the surface of the object to be cleaned is decomposed into carbon and carbon dioxide in alkaline electrolyzed water, the alkaline electrolyzed water is preferably pH 11 to pH 13. Unless the alkaline electrolyzed water has a pH of 11 or more, the effect of alkaline degreasing is not sufficiently exhibited, and industrially required production efficiency cannot be obtained. On the other hand, using alkaline electrolyzed water exceeding pH 13 is not preferable because the alkaline degreasing effect is saturated and the chemical is wasted.

  In preparing the alkaline electrolyzed water, it is preferable to use “alkaline electrolyzed water having a purity of 99.9% by mass or more”. This is because when “alkaline electrolyzed water having a purity of less than 99.9% by mass” is used, degreasing performance may vary depending on trace elements contained in water.

Object to be cleaned: The object to be cleaned in the present invention is not particularly limited as long as it is an object that becomes a cathode electrode by immersing it in alkaline electrolyzed water and applying a voltage to the anode electrode. . Accordingly, the objects to be cleaned are “metal products having conductivity”, “plastic plating products having at least a surface layer having conductivity”, “conductive plastic products”, and the like. It should also be noted that there are no particular limitations on the shape, size, etc. of these objects to be cleaned.

Hydrogen bubble: In the present invention, an object to be cleaned and an anode electrode are placed in alkaline electrolyzed water, and the object to be cleaned is cathode-polarized by energizing between the object to be cleaned and the anode electrode. Hydrogen bubbles are formed on the surface of the object. The hydrogen bubbles at this time are preferably micro-nano bubbles having a bubble diameter of 20 nm to 10 μm. When the diameter of the bubbles is less than 20 nm, it is difficult to confirm the diameter of the bubbles, and is set as a temporary lower limit value. On the other hand, if the bubble diameter exceeds 10 μm, the surface of the object to be cleaned has a fine uneven shape, etc., and the bubble diameter is too large to make it difficult for the bubbles to enter the recess. This is not preferable because a degreasing effect cannot be obtained.

  Here, “micro / nano bubbles” will be described. “Micronano bubbles” is a term for indicating that “micro bubbles” and “nano bubbles” are present in a mixed state in a solution. “Microbubble” generally refers to fine bubbles having a diameter of 1 μm to 10 μm. The “nanobubble” is a finer bubble than a microbubble, and generally a nanobubble having a size of 1 μm or less is called a nanobubble. Since the bubbles at this time are extremely fine, even if they are generated, they cannot be confirmed with the naked eye, and appear to be transparent water.

  The technology for producing nanobubbles has not been completely established yet, “a method of generating by crushing microbubbles”, “a method of generating using SPG (shirasu porous glass) film”, “pressurized gas, A method of releasing from a film having a hole with a nano-level opening diameter is employed. On the other hand, in the case of the invention according to the present application, the alkaline electrolyzed water is electrolyzed by arranging the object to be cleaned and the anode electrode in the alkaline electrolyzed water and energizing the object to be cleaned and the anode electrode. “Micro-nano bubbles” including “hydrogen nano-bubbles” can be generated on the surface of the object to be cleaned which is treated and becomes a cathode electrode. In particular, by adding 2.8 g / L or more of potassium carbonate to alkaline electrolyzed water, more efficiently generating “micronanobubbles” including “hydrogen nanobubbles” on the surface of the object to be cleaned. I can do it.

  Furthermore, it is preferable to add potassium hydroxide to alkaline electrolyzed water in addition to this potassium carbonate. It is preferable that potassium carbonate and potassium hydroxide are combined and added to the alkaline electrolyzed water so that the total concentration thereof is 2.8 g / l to 5.6 g / l. When the total concentration of potassium carbonate and potassium hydroxide is less than 2.8 g / l, it is not possible to achieve a certain effect of hydrogen micro-nano bubble generation efficiency by adding the potassium carbonate and potassium hydroxide. On the other hand, when the total concentration of potassium carbonate and potassium hydroxide exceeds 5.6 g / l, the generation effect of hydrogen micro-nano bubbles is saturated and the chemical is wasted, which is not preferable.

Further, current conditions in the electrolysis ^process, it is preferable to use a current in the range of ^{5000mA / dm 2 ~15000mA / dm 2} . In the case of a current value of less than 5000 mA / dm ² , the degreasing speed is slow and the productivity required in industrial production is not satisfied, which is not preferable. On the other hand, when a current value exceeding 15000 mA / dm ² is adopted, if unevenness is present on the surface of the object to be cleaned, current concentration on the convex part becomes remarkable, and the surface of the object to be cleaned can be electrolytically degreased uniformly. Since it becomes difficult, it is not preferable.

  Furthermore, the treatment time of the electrolytic treatment is preferably in the range of 3 seconds to 5 seconds. Here, when the treatment time of the electrolytic treatment is less than 3 seconds, it is difficult to sufficiently perform electrolytic degreasing treatment on the surface of the object to be cleaned, which is not preferable. On the other hand, when the treatment time of the electrolytic treatment exceeds 5 seconds, the electrolytic degreasing ability is saturated, which is not preferable in view of the treatment efficiency.

Occurrence of cavitation phenomenon: In the case of the present invention, by destroying the above-mentioned hydrogen bubbles, a cavitation phenomenon accompanying the destruction of hydrogen bubbles occurs near the surface of the object to be cleaned, and the contamination adhered to the surface of the object to be cleaned Remove objects. First, a method for “destruction of hydrogen bubbles” will be described. As described above, in the case of hydrogen bubbles in a micro-nano bubble state, bubbles corresponding to “nano bubbles” do not disappear as they are unless there is an external factor such as an impact. Therefore, it is preferable to perform “destruction of hydrogen bubbles” by irradiating the hydrogen bubbles in the vicinity of the surface of the object to be cleaned with ultrasonic waves in alkaline electrolyzed water.

  When a hydrogen bubble breaks down, the removal efficiency of contaminants such as oil on the surface of the object to be cleaned increases dramatically due to the shock wave at the time of the break. By using the shock wave of hydrogen bubble destruction in this cavitation phenomenon, it becomes possible to efficiently remove contaminants regardless of the shape of the object to be cleaned and the surface properties of the object to be cleaned. .

Anode: in an electrolytic degreasing method according to the present application, the anode electrode of the above, has an electrode catalyst layer containing iridium oxide in an amount of 10g ^/ m ² ~20g / m 2 on its surface. Here, the anode electrode of the present application, by having the electrode catalyst layer containing iridium oxide in an amount of 10g ^/ m ² ~20g / m 2 on the surface thereof, improvement of durability is achieved, the electrolytic degreasing effect Can be realized stably for a long period of time. The anode electrode of the present application uses an iridium oxide electrode containing iridium oxide as a main component, thereby facilitating generation of hydrogen bubbles and decomposition of oil as described below, and realizing an excellent electrolytic degreasing effect.

  When this iridium oxide electrode is used as an anode electrode, “superoxide anion (active oxygen)” having an oxidizing action can be efficiently generated on the surface of the iridium oxide electrode. This “superoxide anion (active oxygen)” oxidizes the oil removed from the object to be cleaned and decomposes it into “carbon” and “carbon dioxide”. As a result, the oil component floating in the alkaline electrolyzed water disappears, and the removed oil component does not reattach to the surface of the object to be cleaned. At this time, since “carbon” is precipitated in alkaline electrolyzed water, it is preferable to circulate and filter the alkaline electrolyzed water to maintain a clean state.

<About the electrolytic degreasing apparatus according to the present application>
The electrolytic degreasing apparatus according to the present application is an electrolytic degreasing apparatus for cleaning an object to be cleaned using the electrolytic degreasing method described above, and a degreasing tank for storing alkaline electrolyzed water, and the degreasing tank. An anode electrode to be disposed; a current-carrying means for placing the object to be cleaned immersed in alkaline electrolyzed water and cathodic polarization; and a means for destroying a hydrogen bubble near the surface of the object to be cleaned Is. And in the electrolytic degreasing apparatus according to the present application, the circulation filtering means returns the alkaline electrolyzed water overflowed from the degreasing tank to the lower part of the degreasing tank after being filtered by the filtering means. . Hereinafter, the electrolytic degreasing apparatus according to the present application will be specifically described with reference to the drawings.

  In FIG. 1, the schematic explanatory drawing in one Embodiment of an electrolytic degreasing apparatus is shown. The object to be cleaned in the present embodiment is a rolled steel strip 20 on which contaminants such as oil remain on the surface. An electrolytic degreasing apparatus 1 employing the present invention includes a degreasing tank 10 for storing alkaline electrolyzed water, anode electrodes 11 and 11 immersed in the alkaline electrolyzed water, a rectifier 12 as an energizing means, and alkaline electrolyzed water. An ultrasonic irradiation device (ultrasonic irradiation means) 13 is provided as a hydrogen bubble destruction means in the vicinity of the surface of the rolled steel strip 20 to be immersed.

  In the degreasing tank 10, alkaline electrolyzed water is stored. The alkaline electrolyzed water in the present embodiment generally employs an electrolyzed water generating device that is used to generate alkaline electrolyzed water. Further, as the alkaline electrolyzed water, water used within at least 48 hours from the time of electrolyzed water generation is used, and potassium carbonate and potassium hydroxide are added to the alkaline electrolyzed water so as to have predetermined concentrations.

The anode electrode 11 is arranged and used in a state where at least two electrodes are opposed to each other with a predetermined dimension and are immersed in alkaline electrolyzed water. At this time, in the present embodiment, the anode electrodes 11 are arranged so as to face each other substantially in parallel. Each anode electrode 11 and 11, as in the case of electrolytic degreasing method described above, it is preferable to use the iridium oxide electrode mainly composed of iridium oxide in an amount of ^10g / ^{m 2 ~20g} / m 2 on its surface It is more preferable to have an electrode catalyst layer containing iridium oxide.

  Moreover, in the electrolytic degreasing apparatus according to the present application, it is preferable that the degreasing tank 10 includes at least an inner surface made of a material that can reflect ultrasonic waves, and the anode electrode 11 includes a communication portion that can transmit ultrasonic waves. . Here, the anode electrode 11 is provided with a communication part, so that the anode electrode 11 reflects the inside of the degreasing tank 10 without obstructing the path of the ultrasonic wave, and the hydrogen bubbles near the surface of the rolled steel strip 20 are destroyed. Will be promoted. For example, as illustrated in FIG. 2, the anode electrode 11 is formed in a mesh shape and includes a communication portion 11 a, or a punching hole is formed in a plate and includes the communication portion 11 a. This is preferable because the transmittance is increased. In particular, in the present invention, the anode electrode 11 is more preferably formed by a lath net and provided with the communication portion 11a, since the transmittance of ultrasonic waves can be further increased. Further, by making the inner surface of the degreasing tank 10 made of stainless steel, the ultrasonic wave irradiated in the alkaline electrolyzed water is effectively amplified, and the destruction of hydrogen bubbles near the surface of the object to be cleaned is further promoted. Will be.

  In the present embodiment, the rolled steel strip 20 is traveled from one direction (steering portion side) to the other direction (winding portion side) by an unillustrated unreeling portion and winding portion constituting the traveling means. It is. The rolled steel strip 20 fed out from the feeding portion travels between the anode electrodes 11 and 11 disposed in the alkaline electrolyzed water of the degreasing tank 10 and is then wound up by the winding portion. Therefore, the rolled steel strip 20 is positioned between the anode electrodes 11 and 11 facing each other in the alkaline electrolyzed water, and is disposed with a predetermined dimension with each anode electrode 11 and 11.

  Moreover, in order to ensure sufficient time for electrolytic degreasing treatment on the surface of the rolled steel strip 20, the degreasing tank 10 is preferably configured to be long in the traveling direction of the rolled steel strip 20, and similarly, the alkaline property in the degreased tank 10 is set. Each of the anode electrodes 11 and 11 immersed in the electrolytic water is preferably configured to be long in the traveling direction of the rolled steel strip 20. In FIG. 1, the schematic sectional drawing seen from the operation part side or the winding-up part side is shown.

  Then, a positive charge is applied to each anode electrode 11, 11 and a negative charge is applied to the rolled steel strip 20 by the rectifier 12 as the energizing means.

  Moreover, in this degreasing tank 10, the ultrasonic irradiation apparatus 13 is arrange | positioned corresponding to the downward direction of the position where the rolled steel strip 20 travels. This ultrasonic irradiation device 13 is means for irradiating the rolled steel strip 20 with ultrasonic waves of 35 Hz to 45 Hz toward hydrogen bubbles generated near the surface of the rolled steel strip 20, and this embodiment Then, an apparatus with an output of 100 W is adopted. Moreover, in this Embodiment, although the ultrasonic irradiation apparatus 13 is arrange | positioned in the bottom face of the degreasing tank 10, this arrangement | positioning position is not limited to this. Any position may be used as long as the ultrasonic wave can be irradiated toward the vicinity of the surface of the rolled steel strip 20 to which a negative charge is applied.

  Further, FIG. 1 shows that the degreasing tank 10 is provided with a circulating filtration mechanism (circulating filtration means) 30 for alkaline electrolyzed water. The circulation filtering mechanism 30 includes at least a filter 31 as a filtering unit and a pump 32 that conveys alkaline electrolyzed water in the degreasing tank 10 to the filter 31. In this Embodiment, the alkaline electrolyzed water collection | recovery part 16 for circulating and filtering the alkaline electrolyzed water in the degreasing tank 10 is formed in the height position near the water surface of the alkaline electrolyzed water in the degreasing tank 10, and the said A circulation pipe 34 is connected to the alkaline electrolyzed water recovery unit 16. The other end of the circulation pipe 34 is connected to a filter 31, and a pump 32 is connected to the filter 31 via a circulation pipe 35. The pump 32 is connected to an adjustment tank 33, and a circulation return port 15 for returning the alkaline electrolyzed water after filtration to the degreasing tank 10 is connected to the adjustment tank 33 through a circulation pipe 36. . In the present embodiment, the filter 31 is made of polypropylene.

  With the above configuration, the operation of the electrolytic degreasing apparatus 1 according to the present embodiment will be described. First, the traveling means is operated to cause the rolled steel strip 20 that is the object to be cleaned to travel from the feeding portion side toward the winding portion side. The rectifier 12 applies a positive charge to the anode electrodes 11 and 11 immersed in the alkaline electrolyzed water, and applies a negative charge to the rolled steel strip 20.

  Thereby, the alkaline electrolyzed water in the degreasing tank 10 is electrolyzed, and “micro-nano bubbles” including “hydrogen nano-bubbles” are generated on the surface of the rolled steel strip 20 serving as a cathode electrode. Here, ultrasonic waves are irradiated from the ultrasonic irradiation device 13 toward the vicinity of the surface of the rolled steel strip 20. As a result, the “hydrogen bubbles” including “micro-nano bubbles” formed in the vicinity of the surface of the rolled steel strip 20 are broken by ultrasonic waves, and a cavitation phenomenon occurs with the destruction of the hydrogen bubbles, and the rolled steel strip. The contaminant adhering to the surface of 20 is removed from the surface of the rolled steel strip 20.

  On the other hand, when the alkaline electrolyzed water in the degreasing tank 10 is electrolyzed, oxygen bubbles are generated from the surfaces of the anode electrodes 11 and 11. At this time, since the iridium oxide electrode is used as the anode electrode as described above, oxygen generated from the surface of the anode electrode 11 is decomposed and superoxide anions (active oxygen) are efficiently generated. In the vicinity of the surface of the anode 11, the generated superoxide anion (active oxygen) diffuses into the alkaline electrolyzed water in the degreasing tank 10 and reacts with contaminants such as oil separated and removed from the surface of the rolled steel strip 20. The oil is oxidized and decomposed into carbon and carbon dioxide.

  The decomposed carbon dioxide is released into the atmosphere as a gas and processed. On the other hand, by operating the pump 32 of the circulation filtration mechanism 30, the alkaline electrolyzed water containing carbon is formed in the alkaline electrolyzed water recovery unit 16 formed at a height near the surface of the alkaline electrolyzed water in the degreasing tank 10. To the filter 31 via the circulation pipe 34. The filter 31 adsorbs and removes the carbon in the alkaline electrolyzed water, and the alkaline electrolyzed water from which the carbon has been removed enters the degreasing tank 10 from the circulation return port 15 via the circulation pipe 35, the pump 32, and the adjustment tank 33. Will be returned.

  According to the electrolytic degreasing apparatus 1 of the present invention, hydrogen nanobubbles having a diameter of 20 nm to 10 μm are generated on the surface of the cathode steel-polarized rolled steel strip 20, so that even if the surface shape of the rolled steel strip 20 is complicated. In addition, hydrogen nanobubbles having a diameter of 20 nm to 10 μm can penetrate into the concave portion having the surface shape. The hydrogen nanobubbles that have penetrated into the recesses are destroyed by being irradiated with ultrasonic waves, and the contaminants such as oil adhering to the recesses can be effectively removed by the shock wave accompanying the destruction. Thereby, compared with the conventional alkali degreasing method, the cleaning effect outstandingly excellent can be acquired.

  Furthermore, according to the electrolytic degreasing apparatus 1 of the present invention, contaminants such as oil separated and removed from the surface of the rolled steel strip 20 are generated from the surface of the anode electrode during electrolysis of alkaline electrolyzed water. It is oxidized by “anions (active oxygen)” and decomposed into “carbon” and “carbon dioxide”. Since carbon precipitates in alkaline electrolyzed water, the electrolytic degreasing apparatus 1 of the present invention may include a precipitation filtration mechanism (not shown). In this case, the precipitated carbon is removed by the filtration treatment by the precipitation filtration mechanism, and the carbon dioxide is released from the alkaline electrolyzed water to the atmosphere. Thereby, contaminants such as oil components separated and removed from the surface of the rolled steel strip 20 are efficiently decomposed and removed, so that reattachment to the surface of the rolled steel strip 20 can be avoided.

  In the above-described embodiment, the long rolled steel strip 20 wound up in a roll shape is taken out from one direction and taken up from the other direction, but the object to be cleaned in the present invention is used. A thing is not limited to this. For example, as shown in FIG. 2, a plurality of suspension members 22 are provided at a predetermined interval on a conveyance line 21 that constitutes a traveling unit, and an object to be cleaned 23 is detachably attached to the lower end of each suspension member 22. May be. In addition, the object to be cleaned in the present invention may be a plate-like object that cannot be wound as long as it can travel from one direction to the other direction by the traveling means.

  According to the electrolytic degreasing method according to the present application, it is possible to effectively clean the surface of the object to be cleaned, and it is possible to satisfactorily perform the formation of a plating film performed thereafter. Applicable to all required products. In particular, it is suitable for cleaning the surface of a product for which a plating layer is to be formed. By using the electrolytic degreasing method according to the present application, it is possible to efficiently remove contaminants from the surface of the plating object having complex fine irregularities, and prevent the removed oil from being reattached to the surface of the object to be cleaned. A plating layer having good quality can be formed.

  And the electrolytic degreasing apparatus concerning this application does not require a special structure, and apparatus design is also easy. In addition, the electrolytic degreasing apparatus according to the present application can be easily incorporated into a continuous production line such as a plating line or a vacuum vapor deposition line, and can continuously manufacture an object to be cleaned.

DESCRIPTION OF SYMBOLS 1 Electrolytic degreasing apparatus 10 Degreasing tank 11 Anode electrode 11a Communication part 12 Rectifier (energization means)
13 Ultrasonic irradiation device (ultrasonic irradiation means. Hydrogen bubble destruction means)
15 Circulation return port 16 Alkaline electrolyzed water recovery part 20 Rolled steel strip (object to be cleaned)
21 Conveying line 22 Suspended member 23 Object to be cleaned 30 Circulation filtration mechanism (circulation filtration means)
31 Filter (filtering means)
32 Pump 33 Adjustment tank 34 Circulation piping 35 Circulation piping 36 Return piping

Claims (8)

A degreasing method for removing contaminants such as oil adhering to the surface of an object to be cleaned using alkaline electrolyzed water,
The object to be cleaned and the anode electrode are placed in the alkaline electrolyzed water and energized to cathodically polarize the object to be cleaned to form hydrogen bubbles with a diameter of 20 nm to 10 μm on the surface of the object to be cleaned. The hydrogen bubble is destroyed near the surface of the object, and the contaminants attached to the surface of the object to be cleaned are removed by the shock wave accompanying the destruction.
The anode electrode, electrolytic degreasing method characterized by having an electrode catalyst layer containing iridium oxide in an amount of 10g ^/ m ² ~20g / m 2 on its surface.   The electrolytic degreasing method according to claim 1, wherein the alkaline electrolyzed water uses an aqueous solution of pH 11 to pH 13 containing potassium carbonate and potassium hydroxide.   The electrolytic degreasing method according to claim 1 or 2, wherein the hydrogen bubbles near the surface of the object to be cleaned are destroyed by irradiating the hydrogen bubbles with ultrasonic waves in alkaline electrolyzed water.   The superoxide anion generated at the anode electrode being energized and the oil removed from the surface of the object to be cleaned are reacted in the alkaline electrolyzed water to decompose the oil into carbon and carbon dioxide. The electrolytic degreasing method according to claim 3. An electrolytic degreasing apparatus for cleaning the surface of an object to be cleaned using the degreasing method according to claim 1,
A degreasing tank for storing alkaline electrolyzed water;
An anode electrode disposed in the degreasing tank;
An energization means for disposing the object to be cleaned in the alkaline electrolyzed water and cathodicly polarizing the object to be cleaned to form hydrogen bubbles having a diameter of 20 nm to 10 μm on the surface of the object to be cleaned. When,
Hydrogen bubble destruction means for destroying hydrogen bubbles near the surface of the object to be cleaned;
A circulating filtration means for the alkaline electrolyzed water,
The electrolytic degreasing apparatus characterized in that the circulation filtering means returns the alkaline electrolyzed water overflowed from the degreasing tank to the lower part of the degreasing tank after being filtered by the filtering means.   The electrolytic degreasing apparatus according to claim 5, wherein an iridium oxide electrode is used as the anode electrode.   The electrolytic degreasing apparatus according to claim 5 or 6, wherein at least an inner surface of the degreasing tank is formed of a material capable of reflecting ultrasonic waves, and the anode electrode includes a communication portion that allows ultrasonic waves to pass therethrough.   The said hydrogen bubble destruction means is an ultrasonic irradiation means which irradiates an ultrasonic wave in alkaline electrolyzed water with respect to the hydrogen bubble generate | occur | produced on the surface of a to-be-cleaned target object. Electrolytic degreasing equipment.

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