JPH0586497A - Electrodeposition coating method - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an electrodeposition coating method for preventing so-called unpainting due to air pockets in so-called full-dip type electrodeposition coating. [Composition] In an electrodeposition coating method in which a vehicle body is immersed in an electrodeposition tank for electrodeposition coating, a blowout nozzle is provided inside the electrodeposition tank to blow paint toward an air reservoir of the vehicle body, Coating is performed while moving air reservoirs formed on the lower surface, the lower surface of the hood, the inner surface of the roof, and the like by the blowout flow from the blowout nozzle. Also, by installing this blow-out nozzle on the outlet side, the unpainted part will be coated after a sufficient coating film has been formed on the part other than the air reservoir, and the local part that flows to the unpainted part Coating film is formed in a short time by electric current

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called full-dip type electrodeposition coating method, which relates to an electrodeposition coating method for preventing unpainting due to air pockets.

[0002]

2. Description of the Related Art Conventionally, for example, in automobile coating, electrodeposition coating is performed in which the vehicle body is immersed in an electrodeposition tank and the electrodeposition paint in the electrodeposition tank is electrically attached and coated. In other words, the electrodeposition coating has a uniform coating film and can be effectively applied to the edges, welding seams, seams, etc., and the coating film formed on the surface has a low water content, which causes dripping. Since it has advantages such as no accumulation and the like, it is widely applied as a method suitable for painting a vehicle body. Then, for example, the vehicle body conveyed along the conveyer is immersed in a long electrodeposition tank along the conveying direction to run in a submerged state, and the coating film is attached while advancing for a certain period.

[0003]

However, in the case of the conventional electrodeposition coating, air pockets are formed on the inner surface of the roof of the body, the lower surface of the floor, the lower surface of the hood, or the like while the vehicle body is immersed in the electrodeposition tank. There is a problem that a so-called air reservoir is generated and this portion does not come into contact with the electrodeposition paint until the end of immersion, so that a coating film cannot be formed.

[0004]

In order to solve such a problem, the present invention provides a blow-out nozzle for blowing paint toward an air reservoir of the vehicle body on the vehicle body outlet side in the electrodeposition tank,
The air reservoir formed on the lower surface of the vehicle body or the like is moved while being moved by the blowout flow from the blowout nozzle.

[0005]

[Function] The position of the air reservoir is changed by the flow of air from the paint blowing nozzle and the same part is brought into contact with the electrodeposition paint. Has already formed a sufficient coating film and has become non-conductive, and the coating film is formed in a short time by the local current flowing in the newly contacted portion.

[0006]

Embodiments of the electrodeposition coating method of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall view of the electrodeposition tank of the present invention, and FIG. 2 is an enlarged view of the inside of the electrodeposition tank showing a main part of the present invention.

As shown in FIG. 1, in the case of, for example, cationic electrodeposition coating, an overhead conveyor 2 of a cathode of different polarity is provided along the carrying path above the electrodeposition tank 1 charged to the anode. On the hanger 3 of the overhead conveyor 2,
The body W is installed.

[0008] The cathode of the overhead conveyor 2 is electrically connected to the body W, and the body W is dipped in the electrodeposition tank 1 for a predetermined section. Approaching the electrodeposition tank 1.

The inside of the electrodeposition tank 1 is filled with a solution of a cationic electrodeposition coating containing, for example, an amino-modified epoxy resin, carbon, an acetic acid additive, etc., and the bottom surface and side wall surface of the electrodeposition tank 1 are filled. A riser pipe 4 is arranged in the upper part. The riser pipe 4 is connected with an electrodeposition paint blowing nozzle 5 and also with a paint circulation system 6 for circulating the electrodeposition paint in the electrodeposition tank 1.

The paint circulation system 6 is used to circulate the electrodeposition paint in the electrodeposition tank 1 by the pressure feed pump 8 via the filter 7, and the blowing nozzle 5 connected to the circulation pipe 9.
Is equipped with. The blowing nozzles 5 are oriented in the same direction, thereby forming a circulating flow around the fixed direction in the electrodeposition tank 1 to prevent sedimentation and retention of the paint.

By the way, according to the present invention, a separate electrodeposition coating material supply system 10 is constructed inside the outlet side of the electrodeposition tank 1. That is, the electrodeposition paint in the electrodeposition tank 1 is sucked through the filter 11 and is blown out from the blowout nozzles 14a and 14b by the pressure feed pump 12 through the paint supply pipe 13.

The blow-off nozzle 14a on the lower side is
As shown in FIG. 2, the opening is directed upward, and the blowing nozzle 14b along the upper wall surface is opened obliquely upward in the horizontal direction.

That is, air is formed on the floor of the immersed body W, the lower surface of the hood, or the inner surface of the roof, but the blowout nozzle 14a below is directed toward the air accumulated on the lower surface of the floor and the hood. The upper blowing nozzle 14b is directed toward the air accumulated on the inner surface of the roof.

The body W is placed in the electrodeposition tank 1 thus constructed.
As the solution enters and advances, colloids or emulsion particles such as rust-preventive pigments which are charged in the solution are deposited on the surface of the body W to form a coating film. At this time, the adhered coating particles lose their electric charge, and water is circulated into the solution to become insoluble and become an electric resistor. When the coating film is applied to a certain film thickness of, for example, about 20 μm, it becomes Will not conduct electricity and will not be applied anymore.

When the body W approaches the outlet side, the above-mentioned blowing nozzles 14a, 14b of the electrodeposition coating material supply system 10 will be described.
The blowout flow of the electrodeposition paint blown out from is blown toward the air accumulated on the floor lower surface of the body W, the hood lower surface, and the roof inner surface, and moves the position of the air reservoir. For this reason, the electrodeposition paint comes into contact with the air reservoir which has not been contacted until now.

At this point, a coating film of a predetermined thickness has already been formed on the portion other than the air reservoir, and the current locally flows to the portion newly contacted with the electrodeposition coating material, which is applied in a short time. A film is formed.

In this embodiment, the blowing nozzles 14a and 14b of the electrodeposition coating material supply pipe 10 are provided at only one position on the outlet side, but a plurality of them may be provided, or they may be provided in a staggered manner. Is also good.

[0018]

As described above, the electrodeposition coating method of the present invention is
In the coating performed by immersing the car body in the coating liquid by the so-called full dip method, the air pool that occurs during immersion is
Since coating is performed while moving by the blowing flow of the paint blowing nozzle, the unpainted portion is eliminated and the coating quality can be improved. Therefore, for example, the effect of enhancing the rust prevention effect is exhibited.

[Brief description of drawings]

FIG. 1 is an overall view of an electrodeposition tank of the present invention

FIG. 2 is an enlarged view of the inside of the electrodeposition tank showing the main part of the present invention.

[Explanation of symbols]

 1 Electrodeposition tank 10 Electrodeposition paint supply system 14a, 14b Ejection nozzle W body

Claims (1)

[Claims] 1. A method of electrodeposition coating in which a vehicle body is immersed in an electrodeposition tank for electrodeposition coating, wherein paint is blown toward the air reservoir of the vehicle body toward the outlet side of the vehicle body in the electrodeposition tank. An electrodeposition coating method, characterized in that a blowing nozzle is provided, and an air pool formed on a lower surface of a vehicle body or the like is moved while being moved by a blowing flow from the blowing nozzle.