JPH03274298A - Method for controlling electrolyte in diaphragm-electrode device - Google Patents

Abstract

PURPOSE:To clean the periphery of a diaphragm and to efficiently and stably form a high quality coating film by keeping the conductivity of an electrolyte in a diaphragm-electrode structure at a specified value while a power is supplied to the electrode and at a value higher than the specified value when the power supply is stopped. CONSTITUTION:While electrodeposition coating is applied to an automobile body, etc., in a electrodeposition tank 1, the flow control valves 24 and 25 for the acetic acid supply tank 22 and pure water supply tank 23 are controlled by the setting device 26 of an electrolyte control unit 20 to keep the conductivity of the electrolyte in an electrolyte tank 21 at 300-800mus/cm, and the electrolyte is supplied inside the diaphragm 11 through a pipeline 30 and passed from the upper part of an electrode 18 to the lower part to form a coating film on a work. Meanwhile, when the line is stopped, the supply of the electrolyte from the unit 20 to the diaphragm-electrode structure 10 is stopped, and a concd. aq. acetic acid soln. is injected from the tank 41 of a concd. soln. injection means 40 through a pipeline 43 until the conductivity of the electrolyte in the structure 10 is controlled to >=1000mus/cm. Consequently, the concd. soln. flows from the inside of the diaphragm 11 toward its outside, the deposit is easily dropped, and the periphery of the diaphragm 11 is cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for managing polar fluid in a diaphragm electrode device.More specifically, the present invention relates to a method for managing polar fluid in a diaphragm electrode device. It cleans the surface.

[Prior Art 1] Fig. 2 shows an electrodeposition coating system equipped with a diaphragm electrode device.

In the figure, 1 is a T-tank, 2 is a workpiece such as an automobile body,
3 is a transport device, and 5 is a power supply device.

The electrodeposition tank 1 contains an electrodeposition paint liquid, and this electrodeposition paint liquid has a solvent composition consisting of a cationic paint and an acetic acid aqueous solution. Therefore, by connecting the power supply device 5 between the work 2, which is one electrode, and the electrode 18, a coating film can be formed on the surface of the work.

Here, the spacer III electrode device (10, 20+) is provided to remove metal ions eluted from the electrode 18, and has a structure as disclosed in, for example, Japanese Utility Model Application No. 61-53767.

That is, the diaphragm electrode device includes an electrode 18 and a diaphragm ifa structure (upper support member 12, diaphragm body 11.
It consists of a diaphragm electrode structure 10 consisting of a lower support member 13 (see FIG. 3) and an electrolyte management unit 20, which maintains the electrolyte properties within the diaphragm electrode structure 10 constant during electrodeposition coating operation. The properties of the hexaelectrode liquid formed with the device are generally maintained at a conductivity of 300 to 800 μc/cm from the viewpoint of improving electrode efficiency and preventing corrosion of equipment components such as pumps and piping. be.

[Problem to be solved by the invention] By the way, if we pay attention to the inside and outside of the diaphragm IlI body 11 during electrosurgical coating, based on its principle, cations flow from the inside to the outside as shown in FIG. Anions, such as acetate groups (CH, COO-), etc., flow from the inside to the inside by electroosmosis. Therefore, the paint is cationically charged and adsorbed to the workpiece 2.

However, since the composition of the electrodeposition coating liquid is delicate and complex, anionically charged coatings may be contained or appear in the composition.

Then, these paints etc. 100 are applied to the electrode 1 according to the above principle.
It either flows in eight directions or cannot pass through the diaphragm body 11 consisting of an ion exchange membrane or a neutral membrane.

Therefore, it adheres to the outer circumferential surface of the diaphragm 11, causing problems such as lowering the scraping efficiency, inhibiting smooth coating, and deteriorating the quality of the coating film.

Such a problem is being pointed out as an important issue that cannot be ignored these days when it is desired to improve the quality of the negative layer.

The purpose of the present invention is to solve the above-mentioned problems, and to provide a method for managing polar liquid in a diaphragm electrode device that can easily clean the outer circumferential surface of the diaphragm electrode device, thereby stably guaranteeing high-quality coating with high efficiency. It is about providing.

[Means for Solving the Problems] The present invention focuses on the properties of the polar liquid and the solvent for electrodeposition coating, and achieves a diffusion effect without adversely affecting the electrodeposition coating liquid etc. and without making any major changes to the equipment. This is an &R management method that allows you to quickly and easily clean the outer peripheral surface of the diaphragm body.

That is, a method for managing a polar fluid in a diaphragm electrode device comprising a diaphragm electrode structure in which electrodes are arranged in a elliptical space a, and a polar fluid management unit that circulates the polar fluid within this diaphragm electrode structure, comprising: The electrical conductivity of the polar liquid in the diaphragm electrode structure is maintained at 300 to 800 μs/cm while power is being supplied to the electrode, and is increased to 1000 μs/cm or more when power supply is stopped. ] According to the present invention, the electrolytic strength of the electrolyte while power is being supplied to the electrode, that is, during the electric @ painting operation, is 300, which is set from the electrode efficiency etc.
Since the speed is maintained at ~800 μs/cm, predetermined electrodeposition coating can be performed. On the other hand, when the power supply is stopped, that is, when the electrodeposition line is stopped, the polar liquid type conductivity is increased to 1000 μs/cm. Then, the acetic acid groups flow into the tank through the diaphragm due to the diffusion effect of the polar liquid components, so that foreign substances such as paint attached to the outer peripheral surface can be removed.

At this time, since there is no electricity acting on the paint etc., it can be easily removed, and since the polar liquid component and the solvent are the same component, repainting operation can be started without causing any other chemical or other inconveniences.

[Actual knee example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of a diaphragm electrode device suitable for carrying out the present invention.

This diaphragm electrode device consists of a diaphragm electrode structure 10, an electrolyte management unit 20, and a piping system 30 that connects both 10. The configuration includes a highly concentrated liquid injection means 40 for injecting a high concentration liquid.

Therefore, in order to clarify the usefulness of this polar liquid management method,
First, the configuration of the diaphragm electrode device itself will be explained.

First, the diaphragm electrode 'W4 10 is disposed in the electrodeposition tank 1 (only one unit is shown in FIG. 1), and forms a counter electrode for an electrode (workpiece) not shown.

Its structure consists of a tubular diaphragm body 11 formed by injecting a certain type of polymeric material into a tubular shape supported by an upper support member 12 and a lower support member 13, and a cylindrical electric current held within this diaphragm body 11. ! 18 and the upper support material 121111! :
By providing the polar liquid supply pipe 14 and connecting the 'JFfl liquid discharge pipe 15 to the hole 13A of the lower support member 13, a unidirectional flow of the polar liquid from the top to the bottom is formed. By allowing the polar liquid to flow in one direction, even if a corrosion hole 18h occurs in the electrode 18, for example, bypass (short-pass) flow can be blocked and stagnation of the polar liquid in the diaphragm electrode structure 10 can be prevented.

Further, the polar liquid discharge pipe 15 is raised upward, has a horizontal portion 15H, and has a discharge port 15L open to the atmosphere. Therefore, even if a siphon effect occurs in the electrolyte supply pipe 14 due to a failure of the check valve 32 in the piping system 30, for example, the electrolyte in the structure 10 will not flow backwards, so the external pressure of the electrodeposited liquid will cause the diaphragm to This eliminates the need to worry about the body 11 being damaged. In order to eliminate the backflow, the supply port 14A of the polar liquid supply pipe 14 is provided above the liquid level in the diaphragm electrode structure 10 that regulates the horizontal portion 15H. Furthermore, in this embodiment, the rising part of the polar liquid discharge pipe 15 is loosely fitted into the through hole 17 in order to absorb the expansion and contraction of the diaphragm 11 in the electrodeposition liquid while making the flow of the polar liquid unidirectional. Supported. That is, it is supported by the bracket 16 so as to be relatively movable in the vertical direction.

Next, f! The liquid management unit 20 is a means for keeping the properties (conductivity) of the fi liquid constant. Since the electrodeposition paint in this example is cationic, the concentration of the acetic acid aqueous solution is controlled. The electroconductivity of the polar liquid during electrocoating operation is maintained at 300-800 μs/cm.

In other words, the polar liquid management unit 20 has the polar liquid tank 21
．． Acetic acid supply tank 22. It is composed of a pure water supply tank 23, a pair of flow rate adjustment valves (24, 25), a conductivity detection sensor 27, and a setting device 26. Each flow rate adjustment valve 2425 is controlled based on the set value of the setting device 26, and the polar liquid is The electroconductivity of the polar fluid in the tank 21 is kept constant (3,00~800 μs
/' cm ).

Both 10.20 and 31.20 are the piping 31. Pump 35, check valve 32, etc., and liquid receiver 33. They are connected by a piping system 30 that includes a return pipe 34 and the like, thereby forming an electrolyte circulation system.

Further, a drain valve 36 is provided upstream of the pump 35. [4] This is to discharge some or all of the polar liquid into the pit 37 when adjusting the level in the tank 21, replacing the polar liquid, etc. Note that 38 is a filter.

In an embodiment with such a configuration, when a predetermined conductivity is set in the setting device 26, both flow rate regulating valves 2425 are controlled and the electroconductivity of the electrolyte in the electrolyte tank 21 is maintained constant.

Here, the diaphragm electrode structure 10 has a set conductivity of 300 to 8.
00 μs/cm of polar liquid is supplied. Then, the polar liquid becomes a unidirectional flow from above to below within the diaphragm body 11 inside and outside the electrode 18, and M! The liquid discharge pipe 15 is reached. The electrode 18 is thus cooled by the polar fluid flow. Therefore, a predetermined current value (for example, !A/'dm2) can be stably passed between the electrode 18 and the electrode (workpiece) in the electrodeposition bath 1.
Can form high quality coatings.

At this time, the expansion and contraction of the tubular diaphragm 11 is absorbed by the relative displacement between the bracket 16 with the through hole 17 and the km discharge pipe 15. On the other hand, the polar liquid in the diaphragm electrode structure 10 is regulated to a certain extent by the horizontal portion 15H, and the discharge port L5L is opened to the atmosphere, and the polar liquid supply port 14A of the polar liquid supply pipe 14 is
Since the diaphragm body 18 is disposed above the diaphragm 18, even if a siphon effect is applied to the polar liquid supply pipe 14 due to a malfunction of the check valve 32, the possibility that the polar liquid in the diaphragm body 11 becomes empty is eliminated. .

Even if the diaphragm electrode structure 10 etc. is installed horizontally to enable high-efficiency operation and high-quality coating film formation from all angles, if anionized paint or the like adheres to the outer peripheral surface of the diaphragm body 11, It is impossible to expect it to be effective.

Here, this apparatus is provided with the above-mentioned high concentration liquid injection means 40. This means 40 has a conductivity of 1000 μs/
A tank 41 containing a high 4 degree acetic acid aqueous solution of cm or more, a control valve 42 which is opened by a control means (not shown) at an appropriate time when the electrode 8 is not supplied with electricity, that is, the electrodeposition coating operation is stopped, and the tank 41 and the diaphragm electrode. Piping 4 connecting with structure 10
It is formed from 3. Since the conductive dust of the highly concentrated acetic acid aqueous solution is higher than that of the normally used polar liquid, a valve 47 is provided so that the polar liquid tank 21 can be replenished with the acetic acid aqueous solution.

On the other hand, the interval 1 used for cleaning! The highly concentrated liquid in the extremely horizontal remains 10 is removed from the valve 49. By opening and closing the valve 48, it can be discharged to the pit 39, or a part or all of it can be returned to the polar liquid tank 21.

In addition, the pump 46° valve 45. shown by the two-dot chain line in FIG.
The piping is for recirculating the highly concentrated liquid back to the tank 41.

Next, the polar liquid management method of this embodiment will be explained.

(Electrodeposition Coating Operation) The polar fluid management unit 20 causes the polar fluid to continuously flow through the diaphragm electrode structure 10 . Fi! The conductive dust in the liquid is set by the setting device 26.
It is set at 300 to 800 μS/cm.

Here, electric [! When power is supplied to 18, a coating film is formed on the workpiece, and the acetate groups (CH, C00-) in the electrodeposition chamber q solution are separated by electroosmotic action n! ! Flow is included within the electrode structure 10.

At this time, some kind of paint 100 adheres to the outer peripheral surface of the diaphragm 11 as shown in FIG. Therefore, this deposit 1
If 00 is left to accumulate, the electrode efficiency will decrease and it will be impossible to stably form a high quality coating film.

(Line stop) The tili liquid management unit 20 is stopped and the diaphragm electrode structure 1
The polar fluid within 0 stagnates. Naturally, no power is supplied to the electrode 18.

Now, open the control valve 42 and close the electrode!
A highly concentrated liquid is injected into the S remains 10 from the tank 41.

The polar liquid type conductivity in the diaphragm electrode structure 10 is 1000 S/c.
Inject until it reaches m or more. It can be done manually or automatically.

Then, the polar liquid type conductivity in the diaphragm electrode structure 10 is 1000.
tt s/cm or more, which is much higher than that during operation, and since it is cut off from the 'tL pole single pole magnetic 8 source device), the electroosmotic action acts as a diffusion action. That is, the acetic acid groups of the highly concentrated aqueous acetic acid solution flow out through the diaphragm 11 into the electrodeposition tank. In this case, the attachment 100 attached to the outer circumferential surface of the diaphragm body II is not electrically attracted but merely mechanically hooked.Here, the diaphragm body 11
Due to the flow of # acid groups in %R from the inside to the outside ■,
Since the deposit 100 can be easily removed, the outer circumferential surface of the diaphragm 11 can be cleaned while the electrodeposition line is stopped.

(Restart) The highly concentrated liquid in the diaphragm electrode structure 10 is collected into the tank 41 by the pump 46 or transferred to the pit 3 by the valve 48.
You can discharge it to 9.

At this time, it is efficient to start the bong 135 and replenish the #1 liquid from above.

This replaces the polar liquid type conductivity within the diaphragm electrode structure 10 to the usual 300-800 μs/cm.

According to this solid line example, the polar liquid type conductivity within the diaphragm electrode structure 10 is increased to 100% higher than usual during the electrodeposition line stoppage.
The deposit 10 on the diaphragm body 11 is maintained at 0 μs/cm.
Since this is an extremely liquid management method that can eliminate 0 using its diffusion effect, the diaphragm 11 can be easily cleaned without any equipment modification, and it can be used as a high-quality coating that maintains maximum electrode efficiency. Film formation operation can be performed stably.

In addition, since this cleaning is performed while the electrodeposition line is stopped, it may interfere with the production plan, and since the electrode 18 is not supplied with electricity, there is no adhesion.

can be easily made to fall off.

In addition, since the highly concentrated liquid injected is a #acid aqueous solution that is equivalent to the polar solution and the solvent in the electrodeposition coating solution, it does not cause any chemical changes to the entire device, and there is little inconvenience that would cause changes in the quality of the coating. It does not cause any problems and is low cost.

Furthermore, since this cleaning is carried out in the electrodeposition solution, no damage is caused to the diaphragm body 11, which would require the work of pulling the diaphragm electrode structure 10 out of the tank. It can be extended and is economical.

In addition, in the above example, 1000 conductive dust was collected during the power supply stop.
In order to increase the polarity to LLs/cm, it was assumed that a high concentration liquid was injected from the high concentration liquid injection means 40, or by stopping the flow of the polar liquid in the diaphragm electrode 10 for a short time before stopping the power supply to 1000 μS/cm. It is also possible to increase the value even higher. Further, the electrodeposition paint is cationic, and the high concentration liquid is an acetic acid aqueous solution, which is the same as the solvent, or if the solvent is a formic acid aqueous solution, the high concentration liquid can be used as an #i acid aqueous solution.

Furthermore, if the electrodeposition coating material is anionic, it can be carried out as it is, for example by using a highly concentrated amine solution.

[Effects of the Invention] According to the present invention, the polar liquid type conductivity within the diaphragm electrode structure is maintained at 300 to 800 μS/cm while power is being supplied to the electrode, and is increased to 1000 μS/cm or more while power supply is stopped. Since it is a liquid management method, it can be easily cleaned to remove deposits such as paint adhering to the outer peripheral surface of the diaphragm, and has the excellent effect of forming a high-quality paint film efficiently and stably. play.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing an example of a diaphragm electrode device suitable for implementing the present invention, Fig. 2 is a schematic diagram showing a conventional 1gF coating equipment, and Fig. 3 is a conventional electrode management method. FIG. DESCRIPTION OF SYMBOLS 1... Electrodeposition bath, 2... Workpiece, 5... Power supply device, 10... Electrode diaphragm structure, 11... Diaphragm body, 18... Pole, 20... [! Liquid management unit, 30... Piping, 40... High concentration liquid injection means, 41... Tank, 42... Control valve, 43... Piping. 13 Figure Figure

Claims (1)

[Claims] (1) A method for managing polar fluid in a diaphragm electrode device comprising a diaphragm electrode structure in which an electrode is disposed within the diaphragm structure and a polar fluid management unit that circulates the polar fluid within the diaphragm electrode structure, the diaphragm electrode comprising: A method for managing an electrolyte in a diaphragm electrode device, characterized in that the electrical conductivity of the electrolyte in the structure is maintained at 300 to 800 μs/cm while power is being supplied to the electrode, and is increased to 1000 μs/cm or more when the power supply is stopped. .