JP2009242931A - Electrolytic cleaning device and electrolytic cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic cleaning device and an electrolytic cleaning method which can enhance a cleaning effect. <P>SOLUTION: The electrolytic cleaning device 1 and the electrolytic cleaning method comprise immersing an anode 10 and a cathode 20 holding a cleaning object M in an electrolytic cleaning liquid and applying a current between the anode 10 and the cathode 20 to subject the cleaning object to electrolytic cleaning. The anode 10 comprises anodes 10 in which currents are variable with respect to the cathode 20, and is controlled to vary the current with time between the anode 10 and the cathode 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrolytic cleaning apparatus and an electrolytic cleaning method, and more specifically, without corroding or dissolving metal parts such as precision molds made of Fe, steel, stainless steel, Ni, Ti, rare metals, The present invention relates to an electrolytic cleaning apparatus and an electrolytic cleaning method capable of suitably removing adhered dirt such as resin, glass, rubber, abrasive, and smut, metal oxides such as rust and oxide film, and dirt such as discoloration.

  If resin molding is repeated using a mold at high temperature and high pressure, the gas generated by the thermal decomposition of the resin and additives will burn into the mold, or burnt resin may adhere, and in some cases, corrosion will occur. In some cases, an oxide film containing an active substance is formed. If this is left without proper maintenance, the mold may be corroded and damaged. Conventionally, metal parts such as molds with such dirt attached are often maintained by a method of manually polishing and removing them or by ultrasonic cleaning. However, these methods are troublesome, and the stains with strong binding force cannot be removed sufficiently.

  Therefore, as a cleaning method that can effectively remove such a stain having a strong binding force, a cleaning method using electrolysis has been proposed (for example, Patent Document 1, Patent Document 2, and Patent Document 3). .

  The basic principle of electrolytic cleaning is to push up the dirt with gas generated when the electrolytic cleaning solution is electrolyzed and peel it off. In general, additives such as chelating agents are added to the electrolytic cleaning solution, and these additives coordinate and block the metal ions dissolved in the electrolytic cleaning solution, so that the metal ions are cleaned. This prevents damage such as burning and discoloration.

  However, these additives are gradually decomposed and consumed by the electrolytic reaction, and when the cleaning liquid components are decomposed and consumed more than a certain amount, the function of sequestering metal ions as described above is rapidly lost, and cleaning is performed. The object becomes damaged. Therefore, the period from the state before use to this state is the life of the electrolytic cleaning solution. It is known that the life of the electrolytic cleaning solution and the energization amount are in an inversely proportional relationship according to Faraday's law of electrolysis (for example, Non-Patent Document 1). That is, if the energization amount is increased, the life is shortened, and conversely if the energization amount is decreased, the life is lengthened.

JP-A-11-128853 JP 7-214570 A JP-A-9-164533 “Plastics” Japan Plastics Federation, 58 (December 2007), p55-57

  Until now, it has been considered that the cleaning effect and the energization amount are in a proportional relationship. Therefore, in order to increase the cleaning effect, a method of increasing the energization amount has been adopted.

  However, in electrolytic cleaning, there is a case where the possibility of causing damage such as burning or discoloration to the object to be cleaned increases rapidly when a certain amount of energization is exceeded, and there is a limit to the amount of energization that can be increased. Therefore, a method different from the conventional method for simply increasing the energization amount is required as a method for enhancing the cleaning effect.

  Then, an object of this invention is to provide the electrolytic cleaning apparatus and the electrolytic cleaning method which can improve a cleaning effect.

  The electrolytic cleaning apparatus according to the present invention is an electrolytic cleaning apparatus for electrolytically cleaning an object to be cleaned by immersing an anode and a cathode holding an object to be cleaned in an electrolytic cleaning liquid, and applying a direct current between the positive and negative electrodes. It is configured to be controllable so that the energization amount between the positive and negative electrodes changes with time.

  In addition, the electrolytic cleaning method according to the present invention is an electrolytic cleaning method in which an anode and a cathode holding an object to be cleaned are immersed in an electrolytic cleaning liquid, and the object to be cleaned is electrolytically cleaned by applying a direct current between the positive and negative electrodes. The amount of current flowing between the positive and negative electrodes is controlled to change with time.

  According to the electrolytic cleaning apparatus and the electrolytic cleaning method configured as described above, the cleaning effect can be improved as compared with the conventional electrolytic cleaning apparatus and the electrolytic cleaning method in which the amount of current flowing between the positive and negative electrodes is always constant. One of the reasons why such an effect is exhibited is that the gas generation state in the object to be cleaned held by the cathode constantly changes because the amount of current constantly changes, so that the cleaning action such as the peeling action is the object to be cleaned. It is conceivable that it can be effectively added to dirt attached to an object.

  Further, it is preferable that the energization amount is controlled by a voltage applied between the positive and negative electrodes.

  In this way, since the amount of energization can be controlled by controlling the voltage, the amount of energization can be easily controlled.

  Further, in the above configuration, it is preferable that a plurality of voltages having different magnitudes can be applied between the positive and negative electrodes, and the plurality of voltages are alternately switched every predetermined time.

  In this way, the energization amount can be easily numerically controlled.

  In addition, the structure set so that the time average value of the voltage applied between the said positive and negative electrodes may be 3.25V or more and 6.25V or less is preferable.

  In this way, the lifetime of the electrolytic cleaning liquid can be maintained longer.

  The anode is preferably formed using Fe, Pt, Pd, Ir, Ru, or an alloy thereof.

  Alternatively, the anode may be formed by coating an anode body made of Ti with Pt, Pd, Ir, Ru, or an alloy thereof.

  The electrolytic cleaning apparatus preferably includes an ultrasonic generator that ultrasonically vibrates the electrolytic cleaning liquid.

  In this way, the electrolytic cleaning liquid can vibrate ultrasonically, thereby facilitating the removal of dirt attached to the object to be cleaned.

  The electrolytic cleaning solution contains at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and sodium citrate as an electrolyte, and carboxy as a chelating agent. Contains a chelating agent that coordinates a metal ion with a rate group (COO-) and a nitrogen (N) atom, and a gluconate, and as a surfactant, a neutral surfactant, an amphoteric surfactant, an anionic interface A configuration containing at least one of the activators is preferable.

  As described above, according to the present invention, the cleaning effect can be improved. Therefore, since the electrolytic cleaning can be performed in a short cleaning time, it is possible to use the electrolytic cleaning liquid for a long time, so that the running cost can be reduced, and the frequency of waste liquid generation is reduced and the environment is reduced. This can also reduce the load.

  Embodiments of an electrolytic cleaning apparatus and an electrolytic cleaning method according to the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the electrolytic cleaning apparatus 1 according to the first embodiment immerses the anode 10 and the cathode 20 holding the object to be cleaned M in an electrolytic cleaning solution, and between the anode 10 and the cathode 20. The object to be cleaned M is electrolytically cleaned by flowing a direct current. In the following, first, a schematic description will be given of the configuration of the electrolytic cleaning apparatus 1 itself. The electrolytic cleaning apparatus 1 includes, in addition to the anode 10 and the cathode 20, a housing 2, a cleaning tank 3 that is disposed on the top of the housing 2 and stores an electrolytic cleaning liquid, and a positive cathode (anode 10 and cathode 20). A controllable power source 4 is provided inside the housing 2 so that power can be supplied by changing the energization amount between them.

  The anode 10 is provided such that a metal discharge portion 12a, which will be described later, is located inside the cleaning tank 3, and the discharge portion 12a is immersed in an electrolytic cleaning solution during electrolytic cleaning. Specifically, as shown in FIG. 2, the anode 10 is suspended from the opening at the upper end of the cleaning tank 3.

  The anode 10 is disposed so that the discharge portion 12a is positioned on a plane along a horizontal plane. Specifically, the anode 10 includes the anode body 12 having the discharge portion 12a and a support body 13 that supports the anode body 12. It is prepared for. The anode 10 is a member as shown in FIG. 3A, and has a plurality (for example, 4 to 10) of anode bodies 12. As the anode body 12, a disk-shaped metal (diameter 36 mm) having a circular plane portion is used. The anode bodies 12 are provided in pairs. Further, as shown in FIG. 3B, the anode body 12 is covered with an insulator 12b such as a resin at the outer periphery of the portion immersed in the electrolytic cleaning liquid except for the discharge portion 12a.

  The anode body 12 is configured such that the height position relative to the support body 13 can be adjusted, and is fixed at an arbitrary height direction position. Moreover, the anode body 12 is arrange | positioned so that the space | interval of the metal discharge part 12a and the upper end surface of the cleaning target M may be 20-50 mm, and 30 mm is especially preferable. If it does in this way, it can wash suitably, without generating damage, such as a burn and discoloration, to washing object M.

  The anode 10 (that is, the anode body 12) is formed using Fe. Since Fe is inexpensive, the cost of the electrolytic cleaning apparatus 1 can be reduced. However, since accumulation of metal ions in the electrolytic cleaning liquid increases the possibility of adsorption to the cleaning object M by changing to oxides or the like, from the viewpoint of preventing this, the anode 10 (that is, the anode body 12) is , Pt, Pd, Ir, Ru, or the like, or a platinum group metal having a low ionization tendency, or an alloy thereof is preferably used. Furthermore, the anode body 12 may be formed by covering an anode body made of Ti with Pt, Pd, Ir, Ru, or an alloy thereof. In this way, the amount of expensive platinum group metal used can be reduced, which is economical.

  As shown in FIGS. 2, 4, and 5, the cathode 20 includes a support member 21 that supports the cleaning object M in a state of being electrically connected to the cleaning object, and a suspension that suspends the support member 21. The lower member 22 is provided. The support member 21 has a metal conductive portion 21 a configured to come into contact with the cleaning object M. Further, the support member 21 has a space 23 that communicates between both surfaces of the support member 21. In this way, since the electrolytic cleaning liquid can flow through the space portion 23 formed in the support member 21, the consumed electrolytic cleaning liquid stays in the gap between the support member 21 and the cleaning object M, and the electrolytic cleaning liquid It is possible to suitably prevent the decomposition component from being seized on the cleaning object M.

  More specifically, as shown in FIG. 4, the support member 21 includes a plurality of rod bodies 24 and a frame body 25 that surrounds the plurality of rod bodies 24. The plurality of rod-like bodies 24 are arranged in parallel at intervals. However, the cathode is not limited to those described above, and may be provided as a tray or basket made of metal such as stainless steel. The support member 21 has an opening upper end portion (specifically, an upper end portion of the frame body 25) bordered by an insulator 21b such as a resin. The suspension member 22 is covered with an insulator 22c such as a resin except for the connection portion 22a to the support member 21 and the connection portion 22b to the power source 4.

  Further, the cathode 20 is particularly suitable for holding a flat object to be cleaned M, and specifically includes a fixing member 30 for fixing the object to be cleaned M as shown in FIG. . The fixing member 30 includes an attachment portion 31 that is detachably attached to the support member 21 and a fixing portion 32 that fixes the cleaning object M. The fixing portion 32 attaches the cleaning object M to the support member 21. It is comprised so that it may be pinched | interposed between.

  The attachment portion 31 includes a contact portion 33 a that contacts the lower surface of the support member 21, and a lower member 33 that includes a screw portion formed on the outer peripheral surface thereof and an insertion portion 33 b that is inserted into the space portion 23 of the support member 21. The upper member 34 has an insertion hole through which the insertion portion 33b of the lower member 33 is inserted, and is in contact with the upper surface of the support member 21, and the lower member 33 and the upper member 34 sandwich the support member 21. And a nut 35 for fixing in a closed state. The fixing portion 32 has an insertion hole through which the insertion portion 33b of the lower member 33 is inserted, and is fixed to the attachment portion 31 side by a nut 36 while being inserted into the insertion portion 33b.

  In addition to the electrolytic cleaning, the electrolytic cleaning apparatus 1 includes an ultrasonic generator (not shown) for ultrasonically cleaning the object to be cleaned by ultrasonically vibrating the electrolytic cleaning liquid. The ultrasonic generator is provided in the lower part of the cleaning tank 3. The ultrasonic cleaning can be performed simultaneously with the electrolytic cleaning or alternately, but is preferably performed simultaneously with the electrolytic cleaning.

  In this way, it is possible to promote the peeling of dirt adhered to the cleaning object M by ultrasonic vibration of the electrolytic cleaning liquid. Specifically, cavitation is generated by ultrasonic vibration, which promotes peeling of dirt and activates the electrolytic reaction. Therefore, a high cleaning effect can be exerted even on a portion not facing the anode body 12 or a recessed portion.

  Further, the electrolytic cleaning apparatus 1 preferably includes a heating device (not shown) for heating the electrolytic cleaning liquid. In addition, as for the liquid temperature which performs electrolytic cleaning, 20-70 degreeC is preferable, In this case, it can wash | clean suitably, without the washing | cleaning target object M producing a burn or discoloration. Furthermore, when the liquid temperature is 50 to 60 ° C., the object to be cleaned M is also damaged by mold stains having relatively strong bonds such as metal oxide film, rust, resin deposits, and gas burn. And can be cleaned most efficiently in a short time.

  Further, the electrolytic cleaning apparatus 1 includes a circulation mechanism (not shown) that discharges the electrolytic cleaning liquid from the cleaning tank 3, removes impurities, and throws the electrolytic cleaning liquid into the cleaning tank 3 again. Here, the circulation mechanism will be specifically described. The cleaning tank 3 is configured such that the electrolytic cleaning liquid is supplied from the bottom, and when the cleaning tank 3 is full, the electrolytic cleaning liquid overflows from a discharge portion provided at a predetermined height. Yes. When electrolytic cleaning is performed, foreign substances such as deposits and bubbles peeled off from the cleaning object M are generated. By overflowing the electrolytic cleaning liquid, these foreign substances and bubbles are also washed with the electrolytic cleaning liquid in the cleaning tank 3. Discharged from. The discharged electrolytic cleaning liquid is purified by a known method such as filtration using a filter, and the cleaned electrolytic cleaning liquid is supplied to the cleaning tank 3 again.

  The cleaning object M to be cleaned by the electrolytic cleaning apparatus 1 is, for example, a gold for injection molding a light guide plate or a sheet-like optical lens of a flat panel display, an ultra-small and precise camera lens of a mobile phone, a vehicle reflector, or the like. It is a type.

  In addition, as the electrolytic cleaning liquid, one containing an electrolyte, a chelating agent, and a surfactant is used. The electrolyte preferably contains at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and sodium citrate. As the chelating agent, those containing a chelating agent that coordinates a metal ion with a carboxylate group (COO-) and a nitrogen (N) atom, and a gluconate are preferable. As the surfactant, those containing at least one of a neutral surfactant, an amphoteric surfactant and an anionic surfactant are preferable, and an amphoteric surfactant is particularly preferable. The electrolytic cleaning liquid is an alkaline aqueous solution having a pH of 8 to 14, and the higher the pH value, the higher the cleaning effect. Further, if cleaning is performed in this pH range, corrosion of the cleaning object made of Fe, steel, stainless steel, Ni, Ti, or rare metals can be ignored.

  In the above electrolytic cleaning solution, the chelating agent coordinates and blocks the metal ions dissolved in the electrolytic cleaning solution, so that it is possible to suitably prevent discoloration of the cleaning object derived from the metal ions. In addition, since the surfactant reduces the surface tension of the electrolytic cleaning liquid, it can increase the permeability with respect to the gaps in the dirt and enhance the cleaning effect. Moreover, since bubbles are generated on the surface of the electrolytic cleaning liquid by the surfactant, it is possible to suitably prevent the alkaline mist generated when the gas generated by the electrolytic cleaning is repelled on the liquid surface.

  Furthermore, if the electrolytic cleaning is performed for a long time, the amount of the liquid decreases due to the evaporation of the electrolytic cleaning liquid or the electrolysis of water. Therefore, the replenisher is appropriately replenished in order to maintain the liquid amount at the start of the electrolytic cleaning. The replenisher may be water, but preferably contains an electrolyte, a chelating agent, and a gluconate, and more preferably contains a surfactant. As with the above-described electrolytic cleaning solution, the electrolyte contains at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and sodium citrate. preferable. The chelating agent preferably contains a chelating agent that coordinates a metal ion with a carboxylate group (COO-) and a nitrogen (N) atom. As the surfactant, those containing at least one of a neutral surfactant, an amphoteric surfactant and an anionic surfactant are preferable, and an amphoteric surfactant is particularly preferable.

  Next, control of voltage (energization amount), which is a characteristic part of the electrolytic cleaning apparatus 1 and the electrolytic cleaning method according to the present embodiment, will be described.

As shown in FIG. 6, the electrolytic cleaning apparatus 1 is configured to be controllable so that the energization amount between the anode 10 and the cathode 20 changes with time. Specifically, the energization amount is controlled by a voltage applied between the anode 10 and the cathode portion 20.

  The electrolytic cleaning apparatus 1 is configured to be able to apply a plurality of voltages of different sizes between the anode 10 and the cathode 20, and a voltage applied between the anode 10 and the cathode 20 is between these voltages. It can be switched alternately. In the electrolytic cleaning apparatus 1, the voltage applied between the anode 10 and the cathode 20 is switched every predetermined time.

  Note that when the applied voltage falls below about 2 V (so-called overvoltage), the current stops flowing and the electrolytic gas cannot be generated. Therefore, the maximum value of the applied voltage that varies over time is set to at least the overvoltage or more. The Further, when the applied voltage is increased, the energization is excessive, the life of the electrolytic cleaning solution is rapidly shortened, and the cleaning target M is easily damaged or burned. Therefore, the voltage applied between the anode 10 and the cathode 20 is preferably set so as not to exceed at least 12V, and more preferably does not exceed 10V.

  By the way, since the electrolytic cleaning liquid is generally expensive and has a high ratio to the running cost, there is a problem that the running cost becomes high if the life is short. Also, it is not preferable to frequently discard the used electrolytic cleaning liquid because the environmental load is increased by increasing the amount of waste liquid. Furthermore, if the replacement frequency is high, there is a problem that the working efficiency of the entire electrolytic cleaning is lowered. Therefore, it is preferable that the lifetime of the electrolytic cleaning liquid can be maintained long. For this reason, the electrolytic cleaning apparatus 1 is set such that the time average value of the voltage applied between the positive and negative electrodes is 3.25V or more and 6.25V or less.

  Hereinafter, the present invention will be described in more detail with reference to test examples. However, the present invention is not limited to the description of only these test examples, and can be appropriately changed within the scope of the object of the present invention.

<Test Example 1>
In Test Example 1, using an experimental apparatus as shown in FIG. 7, a test was performed in which a sample S in which a circular (φ6 mm) resin R was adhered to four locations on the surface of the Fe plate 41 was electrolytically cleaned. In addition, since the sample S used for the detergency evaluation has a difference in ease of peeling depending on the adhesion state (size and shape) of the resin R, in order to accurately evaluate the detergency, a homogeneous sample is obtained by the following method. Produced. First, an Fe plate (length 100 mm, width 25 mm, thickness 0.25 mm) was degreased and washed by cathodic electrolysis in a 5 wt% aqueous sodium hydroxide solution for several seconds, washed with water and dried. Next, a masking tape having 6 mm diameter holes provided at four intervals at intervals of 10 mm is applied to the Fe plate, and an acrylic silicon resin (an oily supercoat manufactured by Asahi Pen Co., Ltd.) is applied on the masking tape. Was peeled off and dried at room temperature and normal pressure for 14 hours or more.

  Then, as shown in FIG. 7, the sample S (Fe plate 41 with the resin attached) was used as a cathode, the Fe plate 42 with nothing attached was used as an anode, and the anode and the cathode were separated from each other by 50 mm. In a state, it was placed in a 100 mL beaker containing 100 mL of electrolytic cleaning solution.

  As an electrolytic cleaning solution, an alkaline aqueous solution containing 4.5 wt% sodium hydroxide, 5 wt% ethylenediaminetetraacetic acid / tetrasodium, 2% sodium gluconate, and a trace amount (for example, 1 wt% or less) of an amphoteric surfactant is used. An electrolytic cleaning solution (pH 13.6) was used.

  Then, a first voltage E1 and a second voltage E2 are set as voltages to be applied to the Fe plate 42 serving as the anode, and these two voltage values are switched and applied at a predetermined ratio within a predetermined time T. did. The application time at the second voltage E2 was X% with respect to the predetermined time (that is, the period T). (Therefore, the application time at the first voltage E1 is 100% −X% with respect to the period T.) The time average of the applied voltage is Ea = E1 × (100% −X%) + E2 × X% Can be obtained. The liquid temperature was maintained at 25 to 35 ° C.

  And the time when it was confirmed that the resin R adhering to the Fe plate 41 was peeled was measured. The peeling time of the resin R was the average of the time when the four resins R were peeled. Specifically, as shown in Table 1, the settings of the first voltage E1, the second voltage E2, and the period T were changed to be test examples 1a to 1q. These are shown in Table 1.

<Comparative Example 1>
Comparative Example 1 is basically the same as Test Example 1 except for the voltage applied to the Fe plate 42 as the anode. In Comparative Example 1, a constant voltage was always applied without changing the applied voltage. And the time when it was confirmed that the resin R adhering to the Fe plate 41 was peeled was measured. Specifically, the setting of the voltage to be applied was changed to be Comparative Examples 1a to 1d. These are shown in Table 1.

  As a result of the above measurement, it was confirmed that the electrolytic cleaning power of Test Example 1 was higher than that of Comparative Example 1. In particular, although the time average of the applied voltage of Test Example 1b and the applied voltage of Comparative Example 1b are the same value (6V) (that is, the energization amount is the same), Test Example 1b has the resin peeling time. Was short (that is, the cleaning effect was high).

<Test Example 2>
Test Example 2 is basically the same as Test Example 1 except for those related to the electrolytic cleaning solution. In Test Example 2, 10 wt% potassium carbonate was used as the electrolyte contained in the electrolytic cleaning solution. The pH of the electrolytic cleaning solution was 12.3. Specifically, as shown in Table 2, the settings of the first voltage E1, the second voltage E2, and the cycle T were changed to be Test Examples 2a to 2h.

<Comparative Example 2>
In Comparative Example 2, various conditions are basically the same as in Test Example 1 except for the voltage applied to the Fe plate 42 as the anode. In Comparative Example 1, the applied voltage is not changed. A constant voltage was always applied. And in these Test Example 2 and Comparative Example 2, the time when it was confirmed that the resin adhered to the Fe plate 41 was peeled was measured. Specifically, the setting of the voltage to be applied was changed to be Comparative Examples 1a to 1d. These are shown in Table 2.

  As a result of the above measurement, it was confirmed that the electrolytic cleaning power was higher in Test Example 2 than in Comparative Example 2. In particular, although the time average of the applied voltages of Test Example 2b and Test Example 2d and the applied voltage of Comparative Example 2b are the same value (6 V) (that is, the energization amount is the same), Test Example 2b and Test Example It was confirmed that 2d had a shorter resin peeling time (that is, a higher cleaning effect).

<Test Example 3>
Test Example 3 is basically the same as Test Example 1a except for those relating to the electrolytic cleaning solution. In Test Example 3, the electrolyte shown in Table 3 was used as the electrolyte contained in the electrolytic cleaning solution. Specifically, as shown in Table 3, while changing the electrolyte contained in the electrolytic cleaning solution, the settings of the first voltage E1, the second voltage E2, and the period T were changed, and Test Examples 3a to 3j did. The test example 3e and the test example 2a, and the test example 3j and the test example 2b have the same experimental conditions.

<Comparative Example 3>
Comparative Example 3 was basically the same as Comparative Example 1 except for those related to the electrolytic cleaning solution. In Comparative Example 1, a constant voltage was constantly applied without changing the applied voltage. . The comparative example 3e and the comparative example 2a have the same experimental conditions. And in these Test Example 2 and Comparative Example 2, the time when it was confirmed that the resin adhered to the Fe plate 41 was peeled was measured. Specifically, as shown in Table 3, the electrolytes contained in the electrolytic cleaning solution were changed to Comparative Examples 3a to 3e. These are shown in Table 3.

  As a result of the above measurement, it was confirmed that the higher the pH, the higher the electrolytic cleaning power. In addition, when the test examples 3a to 3e and the test examples 3f to 3j are compared, the test examples 3f to 3j are applied even though the average value of the applied voltage is smaller than 6V (that is, the energization amount is small). It was confirmed that the peeling time was shorter (that is, the cleaning effect was higher) than in Test Examples 3a to 3e where the average value of the voltage was 6.25V.

<Test Example 4>
In Test Example 4, the electrolytic cleaning apparatus 50 shown in FIG. 8 was used. The anode 51 is composed of a disc-shaped anode body (diameter 36 mm), and the cathode 52 is composed of a stainless steel basket having a mesh structure. As the cleaning object M, a steel material (width 30 mm, length 30 mm, height 10 mm) used as a material for a mold or a metal part was used. Then, the object to be cleaned M is placed on the cathode 52, and 1 L of electrolytic cleaning liquid is accommodated in a state where the discharge portion of the anode 51 and the upper end surface of the object to be cleaned M face each other so as to be 30 mm. Placed in a 1 L beaker.

  As an electrolytic cleaning solution, an alkaline aqueous solution containing 4.5 wt% sodium hydroxide, 5 wt% ethylenediaminetetraacetic acid / tetrasodium, 2% sodium gluconate, and a trace amount (for example, 1 wt% or less) of an amphoteric surfactant is used. An electrolytic cleaning solution (pH 13.6) was used.

  Then, a first voltage E1 and a second voltage E2 were set for the anode, and these two voltage values were switched and applied at a predetermined ratio within a predetermined time T. Specifically, the application time at the second voltage E2 is set to X% with respect to the predetermined time (that is, the period T). (The application time at the first voltage E1 is 100% −X% with respect to the period T.) The time average of the applied voltage is obtained by Ea = E1 × (100% −X%) + E2 × X%. be able to. The liquid temperature was maintained at 50-60 ° C.

  Then, every hour, it is verified whether or not the cleaning object M is damaged (specifically, burnt or discolored), and the time until the cleaning object M is confirmed to be damaged is measured. did. For verification, the object to be cleaned M is taken out from the electrolytic cleaning apparatus 50, washed with running water to remove the electrolytic cleaning liquid, then blown and dried with argon gas, and using the naked eye and an optical microscope in a bright environment with illumination or the like. Work to check for damage (specifically, burns and discoloration). Specifically, as shown in Table 1, the settings of the first voltage E1, the second voltage E2, and the period T were changed to be Test Examples 4a to 4p. These are shown in Table 4.

<Comparative example 4>
Comparative Example 4 is basically the same as Test Example 1 except for the voltage applied to the anode. In Comparative Example 4, a constant voltage was always applied without changing the applied voltage. Specifically, the setting of the voltage to be applied was changed to be Comparative Examples 4a to 4e. These are shown in Table 4.

  In all the test examples 4a to 4p, it was confirmed that the lifetime was longer than that of the comparative example 4d having the shortest lifetime. Moreover, as a result of the above measurement, it was confirmed that when the time average of the applied voltage was 6.25 V or less, the life was longer than when it was greater than 6.5 V. In addition, it was confirmed that the lifetime was longer when the time average of the applied voltage was 3.75 V or more than when it was less than 3.5 V. Therefore, it was confirmed that the time average of the applied voltage is preferably set to 3.75V or more and 6.25V or less.

<Test Example 5>
Test Example 5 is basically the same as Test Example 4 except for those related to the electrolytic cleaning solution. In Test Example 5, 10 wt% potassium carbonate was used as the electrolyte contained in the electrolytic cleaning solution. The pH of the electrolytic cleaning solution was 12.3. In Comparative Example 5, various conditions are basically the same as in Test Example 5 except for the voltage applied to the anode. In Comparative Example 5, a constant voltage is applied without changing the applied voltage. Was constantly applied. And the time until it was confirmed that the cleaning target M was damaged was measured. These are shown in Table 5.

<Test Example 6>
As the cleaning object M, a steel material (width 30 mm, length 30 mm, height 10 mm) used for a mold or a metal part was used. In the measurement, four cleaning objects M were used.

  In Test Example 6, the electrolytic cleaning apparatus 1 shown in FIG. 1 was used. Specifically, the anode 10 has six disc-shaped anode bodies 12 (diameter 36 mm). And the said washing | cleaning target object M was put side by side on the said tray, and was set to the electrolytic cleaning apparatus. The anode was arranged so that the distance between the metal discharge portion and the upper end surface of the cleaning object M was 30 mm.

  As an electrolytic cleaning solution, an alkaline aqueous solution containing 4.5 wt% sodium hydroxide, 5 wt% ethylenediaminetetraacetic acid / tetrasodium, 2% sodium gluconate, and a trace amount (for example, 1 wt% or less) of an amphoteric surfactant is used. An electrolytic cleaning solution (pH 13.6) was used. The cleaning tank 3 of the electrolytic cleaning apparatus 1 has a capacity of 10 L, and 9 L of this electrolytic cleaning liquid was charged into the cleaning tank.

  Since the electrolytic cleaning solution decreased during the electrolytic cleaning, water was appropriately supplemented as a replenisher. The amount of replenisher replenished by the end of the measurement was about 1500 mL. Moreover, 40 kHz ultrasonic waves were irradiated simultaneously with the electrolytic cleaning. The liquid temperature was maintained at 45-60 ° C.

  Then, every hour, it is verified whether or not the cleaning object M is damaged (specifically, burnt or discolored), and the time until the cleaning object M is confirmed to be damaged is measured. did. As a verification, the object to be cleaned M is taken out from the electrolytic cleaning apparatus, washed with running water to remove the electrolytic cleaning liquid, blown and dried with argon gas, and using the naked eye and an optical microscope in a bright environment with illumination. Work was done to check for damage (specifically, burns and discoloration). The results are shown in Table 6.

<Comparative Example 6>
In Comparative Example 6, various conditions are basically the same as those in Test Example 2 except for the voltage applied to the anode. In Comparative Example 6, a voltage of 5 V was constantly applied without changing the voltage applied to the anode. The amount of replenisher (water) replenished by the end of the measurement was about 1500 mL. The results are shown in Table 6.

  Moreover, the following tests were conducted as reference examples.

<Reference Example 1>
The same steel material and stainless steel (25 mm in width, 25 mm in length, 2 mm in height) as those used in Test Example 4 were used as samples, and the effects when immersed in an acidic aqueous solution were verified. Specifically, 100 mL of a 10 wt% hydrochloric acid aqueous solution containing 2 wt% aniline was added to a 100 mL beaker, the temperature was kept at 40 ° C., and changes in the surface of each sample were observed. As a result, it was confirmed that hydrogen gas was generated from the surfaces of both the steel material and the stainless steel at about 10 minutes after immersion. Further, when the material was taken out after being immersed for about 60 minutes and observed with the naked eye and an optical microscope, it was confirmed that both the steel material and the stainless steel were corroded and turned light gray.

<Reference Example 2>
An electrolytic cleaning device 50 (see FIG. 8) similar to that used in Test Example 4 was prepared, and a constant DC voltage of 5 V was applied to the sample similar to that used in Test Example 4 as an example for electrolysis. Washing was performed. As a result, the surface of the steel material changed to blackish brown 30 minutes after the start of electrolytic cleaning. The surface of the stainless steel basket used as the cathode also turned black brown.

  From these results, it was found that steel and stainless steel are hardly corroded and dissolved in an acidic aqueous solution for a relatively short time. Moreover, since stainless steel gradually corroded only by making it contact with this acidic aqueous solution, when the washing tank of the washing | cleaning apparatus was made from stainless steel, since the washing tank was gradually corroded, it turned out that handling is difficult.

  As described above, according to the electrolytic cleaning apparatus 1 and the electrolytic cleaning method according to the present embodiment, the cleaning effect can be improved. Therefore, since the electrolytic cleaning can be performed in a short cleaning time, it is possible to use the electrolytic cleaning liquid for a long time, so that the running cost can be reduced, and the frequency of waste liquid generation is reduced and the environment is reduced. This can also reduce the load.

  That is, according to the electrolytic cleaning apparatus 1 and the electrolytic cleaning method according to the present embodiment, the cleaning effect is greater than in the case of the conventional electrolytic cleaning apparatus and electrolytic cleaning method in which the energization amount between the anode 10 and the cathode 20 is always constant. Can be improved. One of the reasons why such an effect is exhibited is that the amount of current flowing between the anode 10 and the cathode 20 with respect to the cathode 20 constantly changes, so that the state of gas generation in the cleaning object M held by the cathode 20 is always constant. Since it changes, it can be considered that a cleaning action such as a peeling action can be effectively applied to dirt adhering to the cleaning object M.

  Further, when the energization amount is changed from a large state to a small state, the generation of gas is suppressed. Here, the electrolytic cleaning liquid is in a state of being constantly stirred by the flow by the circulation means, the vibration by the ultrasonic vibration, the convection generated by the temperature difference, the convection generated by the rising of the gas, or the like. Accordingly, since the gas is removed from the surface of the cleaning object M by stirring the electrolytic cleaning liquid while the generation of gas is suppressed, the electrolytic cleaning liquid can be suitably supplied to the surface of the cleaning object M. The cleaning effect is further enhanced.

  In addition, the amount of energization can be suppressed as compared with the case where a constant voltage is constantly applied, and the life of the electrolytic cleaning solution can be extended accordingly. Moreover, since the amount of heat generated from the anode 10 is reduced by reducing the energization amount, a rapid temperature rise of the electrolytic cleaning liquid can be suppressed. Therefore, it is possible to easily control the temperature of the electrolytic cleaning liquid, and it is also possible to suitably prevent excessive generation of bubbles due to the surfactant added to the electrolytic cleaning liquid.

  Further, since the energization amount can be controlled by controlling the voltage applied between the anode 10 and the cathode 20, the energization amount can be easily controlled.

  The electrolytic cleaning apparatus 1 is configured to be able to apply a plurality of voltages having different sizes between the anode 10 and the cathode 20, and a voltage applied between the anode 10 and the cathode 20 between the plurality of voltages. Are switched alternately. Accordingly, the energization amount can be easily numerically controlled.

  In particular, according to the configuration in which the time average value of the voltage applied between the anode 10 and the cathode 20 is set to be 3.25V or more and 6.25V or less, the life of the electrolytic cleaning solution can be maintained longer. Can do.

  The electrolytic cleaning apparatus and the electrolytic cleaning method according to the present invention are not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

  For example, the waveform of the voltage applied between the positive and negative electrodes can be exemplified as shown in FIG. 9 in addition to that shown in FIG. The configuration shown in FIG. 9A is configured such that three voltages having different magnitudes can be applied between the positive and negative electrodes, and the voltage applied between the positive and negative electrodes is alternately switched between these three voltage values. is there. In the case shown in FIG. 9B, the applied voltage value is not constant, but continuously fluctuates from a low state to a high state. The voltage applied between the positive and negative electrodes may change instantaneously. For example, the voltage shown in FIG. 9C is a voltage that rises instantaneously and then decreases continuously. FIG. 9D shows a case where the voltage falls instantaneously after the voltage continuously rises. In the case of FIG. 9E, the voltage constantly changes without being kept constant. In FIG. 9 (F), the voltage rapidly changes from a low constant value through a maximum value to a value lower than the maximum value, then maintains that value for a predetermined time, and then suddenly decreases to the low constant value. It will change to.

  In the above embodiment, the energization amount is controlled by the voltage applied between the positive and negative electrodes. However, the energization amount between the anode and the cathode can be controlled to change with time. As long as it is a thing, it will not be limited to this, For example, you may change an electric current. Therefore, in principle, the items described as being achieved by changing the voltage, such as the waveform, can also be achieved by a method of changing the energization amount.

  In the above embodiment, the ultrasonic cleaning is performed together, the electrolytic cleaning liquid is circulated, the electrolytic cleaning liquid is filtered, and the replenishing liquid is replenished during the electrolytic cleaning. However, the present invention is not limited to this. Rather, these incidental operations may not be performed during the electrolytic cleaning, and some of these incidental operations may be performed.

The top view of the electrolytic cleaning apparatus which concerns on embodiment of this invention is shown. Sectional drawing of the electrolytic cleaning apparatus which concerns on the same embodiment is shown. The anode of the electrolytic cleaning apparatus which concerns on the embodiment is shown, (A) shows the perspective view of the whole anode, (B) shows the perspective view of the anode body of an anode. The perspective view of the cathode of the electrolytic cleaning apparatus concerning the embodiment is shown. The figure explaining the fixing member with which the cathode of the electrolytic cleaning apparatus which concerns on the embodiment is equipped is shown, (A) is a front view of the state which fixed the washing | cleaning target object to the cathode using the fixing member, (B) is fixing. The top view of the lower member which comprises a member, (C) is a front view of a lower member, (D) shows the side view of a lower member. In the electrolytic cleaning apparatus and the electrolytic cleaning method which concern on the same embodiment, the graph of the waveform of the voltage applied to an anode is shown. The experimental apparatus which concerns on the test example for verifying the effect of this invention is shown. The electrolytic cleaning apparatus which concerns on the test example for verifying the effect of this invention is shown. In the electrolytic cleaning apparatus and the electrolytic cleaning method which concern on other embodiment of this invention, the graph of the waveform of the voltage applied between positive and negative electrodes is shown.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electrolytic cleaning apparatus, 2 ... Housing | casing, 3 ... Cleaning tank, 4 ... Power supply, 10 ... Anode, 12 ... Anode body, 12a ... Discharge part, 12b ... Insulator, 13 ... Support body, 20 ... Cathode, 21 ... Support member, 21a ... conductive portion, 21b ... insulator, 22 ... suspension member, 22a ... connection portion with support member, 22b ... connection portion with power source, 22c ... insulator, 23 ... space portion, 24 ... rod-shaped body 25 ... Frame, 30 ... Fixing member, 31 ... Mounting part, 32 ... Fixing part, 33 ... Lower member, 33a ... Abutting part, 33b ... Insertion part, 34 ... Upper member, 35 ... Nut, 36 ... Nut 41 ... Fe plate as cathode, 42 ... Fe plate as anode, 50 ... electrolytic cleaning device, 51 ... anode, 52 ... cathode, E1 ... first voltage, E2 ... second voltage, M ... object to be cleaned , R ... resin, S ... sample, T ... period

Claims (12)

An electrolytic cleaning apparatus in which an anode and a cathode holding an object to be cleaned are immersed in an electrolytic cleaning liquid, and the object to be cleaned is electrolytically cleaned by applying a direct current between the positive and negative electrodes,
An electrolytic cleaning apparatus configured to be controllable so that an energization amount between the positive and negative electrodes changes with time.   The electrolytic cleaning apparatus according to claim 1, wherein the energization amount is controlled by a voltage applied between the positive and negative electrodes. A plurality of voltages having different sizes are configured to be applied between the positive and negative electrodes,
The electrolytic cleaning apparatus according to claim 2, wherein the plurality of voltages are alternately switched every predetermined time.   4. The electrolytic cleaning apparatus according to claim 2, wherein a time average value of a voltage applied between the positive and negative electrodes is set to be 3.25V or more and 6.25V or less.   5. The electrolytic cleaning apparatus according to claim 1, wherein the anode is formed using Fe, Pt, Pd, Ir, Ru, or an alloy thereof.   5. The electrolytic cleaning apparatus according to claim 1, wherein the anode is formed by coating an anode body made of Ti with Pt, Pd, Ir, Ru, or an alloy thereof.   The electrolytic cleaning apparatus according to claim 1, further comprising an ultrasonic generator that ultrasonically vibrates the electrolytic cleaning liquid. An electrolytic cleaning method in which an anode and a cathode holding an object to be cleaned are immersed in an electrolytic cleaning liquid, and the object to be cleaned is electrolytically cleaned by applying a direct current between the positive and negative electrodes,
An electrolytic cleaning method, wherein the amount of current flowing between the positive and negative electrodes is controlled to change with time.   9. The electrolytic cleaning method according to claim 8, wherein a plurality of voltages having different magnitudes are alternately switched and applied between the positive and negative electrodes every predetermined time.   The electrolytic cleaning method according to claim 9, wherein a time average value of a voltage applied between the positive and negative electrodes is 3.25 V or more and 6.25 V or less.   The said electrolytic cleaning liquid consists of alkaline aqueous solution, The electrolytic cleaning method as described in any one of Claims 8-10 characterized by the above-mentioned. The electrolytic cleaning liquid is
As an electrolyte, it contains at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium citrate,
As a chelating agent, a chelating agent that coordinates a metal ion with a carboxylate group (COO-) and a nitrogen (N) atom, and a gluconate,
The electrolytic cleaning method according to claim 11, wherein the surfactant contains at least one of a neutral surfactant, an amphoteric surfactant, and an anionic surfactant.

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