KR20190101921A - Electro-deposition coating method and electro-deposition coating equipment - Google Patents

Abstract

The present invention relates to an electro-deposition coating method comprising steps of: applying a first current to a subject by passing a conductor between an anode portion and a first cathode portion connected to an external power source in an electrically connected state with the first cathode portion; and applying a second current to the subject by passing the subject between the anode portion and a second cathode portion connected to the external power source in an electrically connected state with the second cathode portion, wherein the first current is controlled by an amount of current through a resistor provided between the external power source and the first cathode portion, and the first current has a lower current amount than the second current.

Description

Electrodeposition coating method and electrodeposition coating device {ELECTRO-DEPOSITION COATING METHOD AND ELECTRO-DEPOSITION COATING EQUIPMENT}

The present invention relates to an electrodeposition coating method and an electrodeposition coating apparatus capable of forming a coating film having a low pinhole generation and having a uniform thickness.

After a vehicle body is completed, a typical automobile body performs a painting process to prevent surface corrosion of the vehicle body and to enhance aesthetics with improved sound insulation. In the painting process, the electrode body is typically subjected to pre-treatment, followed by electroplating to improve adhesion and smoothness, and to coat the vehicle to be half-painted for aesthetic appearance. Thereafter, it is common to coat a clear coat layer to protect the color of the top coat, improve the appearance, and protect the coat from the outside.

The electrodeposition coating is a coating method of immersing a subject in an electrodeposition coating liquid and electrically depositing a coating film on the surface of the subject through a direct current between the subject and the counter electrode, also referred to as electrophoretic coating, electrodeposition coating, and ED coating. Conventional electrodeposition coating apparatus is an electrodeposition tank containing the electrodeposition coating solution, an anolyte tank in which the anolyte solution is stored, a diaphragm electrode receiving the anolyte solution from the anolyte tank, and a bus bar for applying current and voltage to the subject. It includes.

Specifically, in Japanese Patent No. 2,718,736 (Patent Document 1), a plurality of stages of electrodes are disposed from the entry side of the electrodeposition tank to the output side, and the voltage applied from the electrode on the side of the electrodeposition side is higher than the voltage applied from the electrode on the side of the electrodeposition side. A low multi-stage electrified electrodeposition coating device is disclosed. However, when multi-stage energization is performed using a plurality of power sources, such as the electrodeposition coating apparatus of Patent Literature 1, there is a disadvantage in that the economy is inferior.

Therefore, it is necessary to develop and develop an electrodeposition coating method and an electrodeposition coating apparatus capable of forming a coating film having a low thickness and having a uniform thickness on the surface by using a single power source.

Japanese Patent No. 2,718,736 (Published: August 6, 1990)

Accordingly, the present invention does not require the operation of moving the diaphragm electrode even when electrodeposition coating of a subject having a sensitive reaction to high-voltage current exposure, and prevents the voltage shock applied to the object entering the electrodeposition tank, thereby reducing the occurrence of pinholes. An electrodeposition coating method and an electrodeposition coating apparatus capable of forming a coating film of uniform thickness are provided.

The present invention includes the steps of applying a first current to the subject by passing the conductor between the anode portion and the first cathode portion connected to an external power source in an electrically connected state with the first cathode portion; And

Applying a second current to the subject by passing the conductor between the anode portion and the second cathode portion connected to the external power source in an electrically connected state with the second cathode portion; As an electrodeposition coating method,

The first current is adjusted in the amount of current through a resistor provided between an external power source and the first cathode,

The first current provides an electrodeposition coating method in which the amount of current is lower than that of the second current.

The present invention also includes an electrodeposition paint bath, an anode portion, a first cathode portion and a second cathode portion,

A voltage by the same external power source is applied between each of the first cathode portion and the second cathode portion and the anode portion,

At least one resistor is connected between the first cathode and the external power source,

The first current applied to the subject through the first cathode portion provides an electrodeposition coating device having a lower current amount than the second current applied to the subject through the second cathode portion.

The electrodeposition coating method of the present invention can also be coated without the action of moving the diaphragm electrode, even if the subject showing a sensitive reaction to the high-voltage current, and prevents the pinhole generated by preventing voltage shock applied to the object entering the electrodeposition tank. At the same time, a coating film of uniform thickness can be produced.

In addition, the electrodeposition coating apparatus of the present invention has the advantage that the life span of the diaphragm electrode disposed in the portion where the subject enters the electrodeposition is suppressed is suppressed. Furthermore, the electrodeposition coating apparatus according to the present invention uses the same external power supply and regulates the amount of current applied to the subject, thereby suppressing pinhole generation of the coating film and forming a thin film of uniform thickness, and at the same time suppressing pinhole generation through voltage regulation. More economical.

1 and 2 is an embodiment of the electrodeposition coating apparatus and a coating method using the same according to the present invention.

Hereinafter, the present invention will be described in detail.

Electrodeposition coating equipment

1 and 2 is a schematic view showing an example of the electrodeposition coating apparatus and coating method using the same of the present invention.

1 and 2, the electrodeposition coating apparatus according to the present invention includes an electrodeposition coating tank 100, an anode part 300, a first cathode part 210, and a second cathode part 220. Hereinafter, the configuration of the electrodeposition coating apparatus will be described in detail with reference to FIG. 1.

Electrodeposition Paint tank (100)

The electrodeposition paint bath 100 is a space in which the object is accommodated and the overall process of electrodeposition coating of the object is performed, and may be, for example, an electrodeposition tank.

The electrodeposition paint solution 110 is accommodated in the electrodeposition paint bath 100.

The electrodeposition coating liquid 110 is not particularly limited as long as it is a coating liquid usually used in an electrodeposition coating process. For example, the electrodeposition coating liquid 110 may be an aqueous solution containing a drug or paint.

First Cathode (210)

Referring to FIG. 1, the first cathode unit 210 is connected to an external power source 10 and is energized by a cathode (−). In addition, at least one resistor 400 for controlling an amount of current is connected between the first cathode unit 210 and the external power source 10.

The first cathode portion 210 serves to conduct a DC current to the conductor A, and may be a power supply bar connected to an external power source 10 and energized by a cathode (−).

In addition, a first current applied to the object A through the first cathode part 210 is greater than a second current applied to the object A through the second cathode part 220. low. That is, in the electrodeposition coating apparatus according to the present invention, the current applied to the object A in the electrodeposition coating tank 100 may gradually increase as the object A is advanced. As described above, the current applied to the object A on the output side of the electrodeposition coating tank 100 is higher than that on the entry side of the electrodeposition coating bath 100, thereby reducing the coating failure rate of the subject having a reaction sensitive to high current exposure. In addition, by controlling the amount of current applied to the object A as described above, there is an advantage in that the electrodeposition phenomenon of the diaphragm electrode disposed at the portion where the object enters the electrodeposition tank is suppressed and the life is long.

Specifically, the first current may be 0.2 to 0.5 times, or 0.25 to 0.4 times the amount of current of the second current, for example, the first current may be 1 to 25 A, or 2 to 15 A. When the multiple between the first current and the second current is within the above range, there is a slow start effect similar to the two-stage energizing effect.

For example, resistors 400, 401, and 402 for controlling the amount of current may be included between the first cathode unit 210 and the external power source 10. As described above, by controlling the amount of current applied to the object A through the resistors 400, 401, and 402, the coating film having a uniform composition can be manufactured and the pinhole generation of the manufactured coating film can be suppressed. One resistor 400 for controlling the amount of current may be mounted between the first cathode unit 210 and the external power source 10, or a plurality of resistors may be used to facilitate current control for the workpiece. 401 and 402 may be mounted.

The resistors 400, 401, and 402 may generate a resistance to lower the amount of current applied to the object A. FIG. In addition, the resistors 400, 401, and 402 may be 0.5 to 30 Ω, 1 to 20 Ω, or 1 to 10 Ω. The resistance values of the resistors 400, 401, and 402 may be adjusted according to the moving speed and the area of the conductor A. FIG.

Specifically, as shown in FIG. 1, when the resistor is one, the resistor 400 may be 0.5 to 30 Ω, 1 to 20 Ω, or 1 to 10 Ω. In addition, as shown in FIG. 2, when there are a plurality of resistors, the resistors may have the same or different resistance values. For example, the first resistor 401 and the second resistor 402 may each have the same or different resistance values. Specifically, the resistance of the first resistor 401 is 0.5 to 10 Ω, and the second resistor 401 may have a resistance value. The resistance of the resistor 402 may be 0.5 to 10 Ω.

Referring to FIG. 1, the length n of the first cathode part 210 may be shorter than the length m of the second cathode part. That is, when the object A passes through the electrodeposition paint bath 100 at a constant speed, the object A passes through the second cathode portion 220 rather than the time when the object A passes through the first cathode portion 210. The time for which the second current is applied may be longer than that for which the first current is applied to the object A.

Specifically, the length n of the first cathode portion 210 may be 0.01 to 0.3 times the length m of the second cathode portion. When the multiple between the length n of the first cathode portion 210 and the length m of the second cathode portion is within the above range, there is a two-stage conduction effect.

In addition, a voltage by the same external power source 10 is applied between each of the first cathode portion 210 and the second cathode portion 220 and the anode portion 300. That is, the first cathode unit 210, the second cathode unit 220, and the anode unit 300 are connected to the same external power source 10. That is, the same voltage is applied to the conductor A in the electrodeposition paint bath 100. As described above, the electrodeposition coating apparatus according to the present invention uses the same external power supply 10 and adjusts the amount of current applied to the subject A through the resistor, thereby suppressing the pinhole generation of the coating film and forming a uniform thickness film. At the same time, it is more economical than the pinhole generation suppression method using voltage regulation.

2nd Cathode (220)

Referring to FIG. 1, the second cathode unit 220 is connected to an external power source 10 and is energized to the cathode (−).

The second cathode unit 220 serves to conduct a DC current to the conductor A, and may be a power supply bar connected to an external power source 10 and energized by a cathode (−).

For example, a second current is applied to the object A through the second cathode part 200. In this case, the second current may be 10 to 50 A, or 12 to 30 A. When the amount of current of the second current is within the above range, a coating film having a uniform thickness and composition can be produced.

Anode (300)

Referring to FIG. 1, the anode part 300 includes at least one diaphragm electrode. In addition, the anode part 300 is connected to the external power source 10 and is energized to the anode (+).

The diaphragm electrode may be disposed in the electrodeposition paint bath 100 and retain the anolyte solution. Specifically, the diaphragm electrode serves to conduct a DC current between the subject A and the diaphragm electrode by filtering the cations of the anolyte solution retained by the electrodeposition paint solution 110 of the electrodeposition paint bath 100. It may be a diaphragm electrode having a conventional structure in which an ionic membrane is passed through the external power supply 10 to the anode (+) and cations pass and anions are filtered.

For example, referring to FIG. 1, the diaphragm electrode is disposed in the electrodeposition paint bath 100, and at least one portion of the diaphragm electrode in the electrodeposition paint part 100 is immersed in the electrodeposition paint solution 110. May be in a closed state. That is, the diaphragm electrode is a state in which a plurality of at least a portion of the diaphragm electrode is immersed in the electrodeposition paint solution 110 accommodated in the electrodeposition paint bath 100 may be spaced apart from each other.

As another example, the anode part 300 may further include an anolyte storage part (not shown) in which an anolyte is accommodated. In addition, the anolyte solution is accommodated in the anolyte storage unit, and the anolyte storage unit may be, for example, an anolyte tank.

In addition, the anode part 300 may further include a supply line (not shown) and a recovery line (not shown). Specifically, the supply line may supply the anolyte contained in the anolyte storage to the diaphragm electrode, and the recovery line may recover the anolyte in the diaphragm electrode to the anolyte storage. That is, the anolyte may circulate through the anolyte storage unit and the diaphragm electrode.

As an example, the supply line may be provided with an anolyte pump (not shown) for supplying the anolyte contained in the anolyte storage unit to the diaphragm electrode. Specifically, the anode unit 300 includes a supply line, a recovery line and an anolyte pump, the supply line supplies the anolyte solution contained in the anolyte storage unit to the diaphragm electrode with an anolyte pump, and the recovery line is The anolyte in the diaphragm electrode can be recovered back to the anolyte storage.

In addition, the electrodeposition coating apparatus may further include a control unit (not shown) for adjusting the supply of the anolyte. In detail, the controller (not shown) may control supplying the anolyte solution to the diaphragm electrode.

In the electrodeposition coating apparatus of the present invention as described above, the electrodeposition phenomenon of the diaphragm electrode disposed in the portion where the subject A enters into the electrodeposition coating tank 100 is suppressed, and thus the life may be long.

Electrodeposition method

Electrodeposition method according to the present invention comprises the steps of applying a first current to the subject; And applying a second current to the subject. Hereinafter, the electrodeposition coating method will be described in more detail with reference to FIG. 1.

On the subject  Applying a first current

Referring to FIG. 1, in this step, the conductor A is electrically connected to the first cathode portion 210 between the anode portion 300 and the first cathode portion 210 connected to the external power source 10. By passing through the connected state, a first current is applied to the object A. FIG.

The amount of current is controlled by the resistor provided between the external power source 10 and the first cathode unit 210. The resistor is as defined in the electrodeposition coating apparatus.

In addition, the first current and the first cathode portion 210 are as defined in the electrodeposition coating apparatus.

Further, the first current may have a lower current amount than the second current, for example, the first current may be 0.2 to 0.5 times the second current. In this case, the first current and the second current are as defined in the electrodeposition coating apparatus. When the first current is lower than the second current, the voltage A applied to the electrode A to enter the electrodeposition paint tank 100 is prevented, thereby lowering the defective rate and having a sensitive response to high current exposure. The coating may proceed without moving the diaphragm electrode to the rear of the electrodeposition paint bath 100, and the transfer phenomenon of the diaphragm electrode disposed at the portion where the object A enters the electrodeposition paint bath 100 is suppressed. It has the advantage of long life.

The time for which the second current is applied to the subject may be longer than the time for which the first current is applied to the subject. That is, the time for which the second current is applied to the subject may be two to five times the time for which the first current is applied.

In this step, the first coating layer may be formed on the surface of the object A by allowing the object A to pass between the anode part 300 and the first cathode part 210.

In addition, the diaphragm electrode is disposed in the electrodeposition paint bath 100 and holds the anolyte solution.

The diaphragm electrode may be disposed in a state in which at least a portion of the diaphragm electrode is immersed in the electrodeposition paint solution 110 accommodated in the electrodeposition paint bath 100, and when there are a plurality of diaphragm electrodes, they may be spaced apart from each other.

Specifically, the conductor A is electrically connected to the first cathode portion 210 to be energized by the cathode (-), and the conductor A energized by the cathode (-) retains the anolyte solution to the anode ( When passing through the diaphragm electrode energized with (+), the electrodeposition coating liquid 110 in the electrodeposition coating liquid is transferred between the object A and the diaphragm electrode by the principle of electrolysis, electrophoresis, electroprecipitation, and electricity penetration. The first coating layer may be formed on the surface of the object A by being stuck to the surface of (A).

On the subject  Applying a second current

Referring to FIG. 1, in this step, the conductor A is connected to the second cathode portion 220 between the anode portion 300 and the second cathode portion 220 connected to the external power source 10. The second current is applied to the to-be-contained object A by passing it in the electrically connected state.

As an example, the second coating film layer is formed on the first coating film layer by passing the object A on which the first coating film layer is formed to pass the second cathode portion 220 disposed in the electrodeposition coating bath 100. Can be formed.

The second coating layer may be formed on the first coating layer by passing the object A on which the first coating layer is formed and passing through the diaphragm electrode. Specifically, the conductor A is electrically connected to the second cathode portion 220 and is energized to the cathode (-), and the diaphragm electrode to which the conductor A is energized to the anode is energized to the anode (+). When passing, the paint in the electrodeposition coating liquid adheres to the surface of the subject A by the principle of electrolysis, electrophoresis, electroprecipitation, and electricity penetration between the subject A and the diaphragm electrode. The second coating layer may be formed on the second coating layer.

The electrodeposition coating method according to the present invention may include the step of entering the subject into the electrodeposition coating bath.

Subjects  Electrodeposition By painting  Entry step

In this step, the subject A is introduced into the electrodeposition paint bath 100 in which the electrodeposition paint solution 110 is accommodated.

The electrodeposition paint bath 100 is a space in which the object A is accommodated and the overall process of electrodeposition coating of the object A is performed. For example, the electrodeposition paint tank 100 may be an electrodeposition tank.

The electrodeposition coating liquid 110 is not particularly limited as long as it is a coating liquid usually used in an electrodeposition coating process. For example, the electrodeposition coating liquid 110 may be an aqueous solution containing a drug or paint.

The subject A introduced into the electrodeposition paint bath 100 may be in a state where a pretreatment process is performed. In addition, the subject A may be a vehicle body of an automobile.

For example, the object A may enter the electrodeposition paint bath 100 through the conveyor rail.

In the electrodeposition coating method, the current applied to the object A may be gradually changed. Specifically, the electrodeposition coating method may gradually increase the current applied to the object (A). That is, when the conductor A sequentially passes through the first cathode portion 210 and the second cathode portion 220, after the first current is applied to the object A, a second current is applied and the first Since the current is lower than the second current, the current applied to the object A may gradually increase.

The electrodeposition coating method according to the present invention as described above can also be coated without the action of moving the diaphragm electrode even if the conductor that is sensitive to high-voltage current exposure, and prevents the voltage shock applied to the object entering the electrodeposition tank At the same time, it is possible to form a coating film having a uniform thickness, and to reduce the failure rate of the diaphragm electrode disposed at the portion where the subject enters the electrodeposition paint bath, thereby prolonging the service life. In addition, the electrodeposition coating method uses the same external power source and by controlling the amount of current applied to the object, it has an improved economy than the pinhole generation suppression method through the voltage control.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are only for the understanding of the present invention, and the scope of the present invention in any sense is not limited to these examples.

[ Example ]

Example  One.

Electrodeposition coating was performed using the electrodeposition coating method shown in FIG.

The length n of the first cathode portion was 1 m, the length m of the second cathode portion was 13 m, the external power supply was constantly supplied at 250 V, and a current of 16 A was set to flow.

Two 2Ω resistors were provided between the first cathode portion and the external power source, so that a current of 4 A was applied to the subject through the first cathode portion and 16 A of a current was applied to the subject through the second cathode portion. At this time, the electrodeposition coating condition of the car body to be coated was 1,580 ㎲ / cm electrical conductivity was applied for 3 minutes, KCO ECO 2200 Black was used as the coating liquid.

Example  2.

As a resistor, a first resistor having a resistance of 1Ω and a second resistor having a resistance of 2Ω are provided, except that a current of 5.3 A is applied to the subject through the first cathode portion and 16 A of a current is applied to the subject through the second cathode portion. Then, electrodeposition coating was carried out in the same manner as in Example 1.

Example  3.

A first resistor having a resistance of 1Ω and a second resistor having a resistance of 0.5Ω are installed between the first cathode portion and the external power supply, so that a current of about 10.7A is applied to the subject through the first cathode portion and 16A through the second cathode portion. Electrodeposition was carried out in the same manner as in Example 1 except that a current was applied.

Example  4.

Except that two resistors of 4Ω are provided between the first cathode portion and the external power source, except that a current of 2 A is applied to the subject through the first cathode portion and a current of 16 A is applied through the second cathode portion. Electrodeposited coating was carried out in the same manner as in 1.

Comparative example  One.

In the electrodeposition paint method shown in FIG. 1, except that a resistor is not provided between the first cathode portion and the external power supply, the current amount applied to the object through the first cathode portion and the second cathode portion is equal to 16A. Electrodeposition coating was performed by the same method as Example 1.

Comparative example  2.

Electrodeposition coating was performed in the same manner as in Comparative Example 1 except that the voltage 125 V applied to the first cathode portion was adjusted to 0.5 times the voltage 205 V applied to the second cathode portion.

Experimental Example

The number of pinholes generated for 120 vehicle bodies painted in Examples and Comparative Examples was visually measured and shown in Table 1 below.

division Pinhole occurrences Example 1 One Example 2 Three Example 3 5 Example 4 7 Comparative Example 1 18 Comparative Example 2 5

As shown in Table 1, in the to-be-painted body (car body) coated in Examples 1 to 4, there were very few targets having pinholes. The fact that such pinholes do not occur much is determined as a result of preventing the voltage shock applied to the object entering the electrodeposition tank. In particular, Examples 1 and 2 had a significantly smaller number of pinholes.

On the other hand, the coated object in Comparative Example 1 markedly had 18 pinholes. In addition, although the number of the pinholes generated in the conductive material coated in Comparative Example 2 was small, there was a limit in economic efficiency when performing a plurality of stages of energization using a plurality of power sources.

10: external power A: conductor
100: electrodeposition coating bath 110: electrodeposition coating liquid
210: first cathode portion 220: second cathode portion
300: anode part 400, 401, 402: resistor
n: length of first cathode portion m: length of second cathode portion

Claims (6)

Applying a first current to the subject by passing the subject between the anode portion and the first cathode portion connected to an external power source in an electrically connected state with the first cathode portion; And
Applying a second current to the subject by passing the conductor between the anode portion and the second cathode portion connected to the external power source in an electrically connected state with the second cathode portion; As an electrodeposition coating method,
The first current is adjusted in the amount of current through a resistor provided between an external power source and the first cathode,
And the first current has a lower current amount than the second current. The method according to claim 1,
And the first current is 0.2 to 0.5 times the second current. The method according to claim 1,
The electrodeposition coating method in which the time which the said 2nd electric current is applied to the to-be-conducted body is longer than the time which the said 1st electric current is applied to the to-be-conducted body. Including an electrodeposition paint bath, an anode portion, a first cathode portion and a second cathode portion,
A voltage by the same external power source is applied between each of the first cathode portion and the second cathode portion and the anode portion,
At least one resistor is connected between the first cathode and the external power source,
The electrodeposition coating apparatus in which the 1st electric current applied to the to-be-conducted body through the said 1st cathode part is lower than a 2nd electric current applied to the to-be-conducted body through the said 2nd cathode part. The method according to claim 4,
The electrodeposition coating apparatus of Claim 1 whose length of a said 1st cathode part is shorter than the length of a 2nd cathode part. The method according to claim 4,
The electrodeposition coating device including a plurality of resistors between the first cathode portion and the external power source.

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