JP2001214300A - Cathodic electrodeposition coating method - Google Patents

Abstract

(57) [Summary] (Problem corrected) [Problem] To provide a cationic electrodeposition coating method capable of obtaining a coating film having no defective appearance in a cationic electrodeposition coating method in which a drying oven is provided in a line but is not used. I do. SOLUTION: In the cation electrodeposition coating method of performing rinsing by immersing a surface-treated base material 2 in a water tank and then immersing the base material in an electrodeposition bath 5 to perform cation electrodeposition. Is performed and water is sprayed several times before immersion in the electrodeposition bath.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cationic electrodeposition coating method, and more particularly to a cationic electrodeposition coating method in a factory line.

[0002]

2. Description of the Related Art Cathodic electrodeposition coating is applied to an automobile outer panel for anticorrosion properties. This cationic electrodeposition coating
Usually, it is performed on a substrate that has been subjected to a surface treatment, but in a factory, these are lined.

[0003] In the previous cation electrodeposition coating line, a surface-treated substrate was immersed in a water tank, washed with water, heated in a drying furnace to dry the substrate, and then subjected to an electrodeposition bath. For cationic electrodeposition coating. However, in recent years, from the viewpoint of energy saving, in such a line, a substrate washed with water has been immersed in an electrodeposition bath without using a drying furnace.

[0004]

In a line in which such a drying furnace is not used, but is left as it is, the time from rinsing with water to immersion in an electrodeposition bath is long, so that the surface of the substrate is The evaporation of a part of the water causes uneven drying. When the electrodeposited coating is applied to the substrate on which the drying unevenness has occurred, the appearance of the resulting electrodeposited coating film may be poor depending on the type of the surface treatment agent used. This problem is particularly remarkable on a substrate having many horizontal surfaces such as a bonnet.

[0005] On the other hand, in order to remove garbage and the like attached between the time of washing with water and the time of immersion in the electrodeposition bath,
A method of spraying water immediately before immersing a substrate in an electrodeposition bath is known. However, even if water is sprayed on the substrate on which the drying unevenness has occurred, the appearance defect of the electrodeposition coating film cannot be solved.

[0006] The present invention provides a cationic electrodeposition coating method capable of obtaining a coating film having no defective appearance in a cationic electrodeposition coating method in which a drying furnace is provided in a line but is not used.

[0007]

In the cationic electrodeposition coating method of the present invention, the surface-treated base material is washed by immersing the base material in a water tank, and then the base material is immersed in an electrodeposition bath. In the cationic electrodeposition coating method for performing electrodeposition, water is sprayed a plurality of times after washing with water and before immersion in an electrodeposition bath.

[0008] Here, one of the multiple sprays of water is performed.
The round can be performed immediately before immersion in the electrodeposition bath. Also,
The time from rinsing to immersion in the electrodeposition bath is, for example, 10 minutes or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the cationic electrodeposition coating method of the present invention, a surface-treated substrate is immersed in a water bath, washed with water, and then immersed in an electrodeposition bath to carry out cationic electrodeposition. In the cationic electrodeposition coating method, water is sprayed a plurality of times after rinsing and before immersion in the electrodeposition bath. Hereinafter, description will be made with reference to FIG.

FIG. 1 is a schematic diagram of the cationic electrodeposition coating method of the present invention. On the cationic electrodeposition coating line 10, there is a surface-treated substrate 2 which is an object to be coated, and it proceeds in the direction of arrow 1. Here, an unused drying furnace 4 is installed between the water tank 3 and the electrodeposition bath 5.

The substrate 2 having been subjected to the surface treatment is first immersed in a water tank 3 so that unnecessary components adhered in the surface treatment step are washed with water. Next, the substrate 2 comes out of the water tank 3,
It enters the drying oven 4 which is not used. In the cationic electrodeposition coating method of the present invention, before the substrate 2 enters the drying furnace 4,
It is preferable to spray water. This is because once the substrate 2 has entered the drying furnace 4, it becomes difficult to spray water. This spraying of water, for example,
Can be performed. Water spraying conditions can be set arbitrarily, for example, 0.5 to 1.0 L
/ Min. By spraying the water in this manner, it is possible to prevent the occurrence of uneven drying.

The substrate 2 having passed through the drying furnace 4 is subsequently immersed in an electrodeposition bath 5 filled with a cationic electrodeposition paint.
It is preferable to spray water again immediately before immersion in the electrodeposition bath 5. This spraying of water is mainly performed for the purpose of removing dust and the like adhering to the base material 2. The spraying of water here can be performed, for example, by the shower 7 under the same conditions as the above spraying.
The substrate 2 thus washed is immersed in an electrodeposition bath 5 and subjected to cationic electrodeposition coating under ordinary conditions.

In the above description, water is sprayed twice, but a shower can be further provided between the water tank 3 and the electrodeposition bath 5, if necessary. In the present invention, since the base material 2 that has exited from the water tank 3 and is immersed in the electrodeposition bath 5 is sprayed with water a plurality of times, drying unevenness does not occur.

[0014]

EXAMPLES The line speed was 0.75 m / min and the time required to reach the electrodeposition bath after leaving the water tank was about 8 minutes. In the cationic electrodeposition coating line using No. 20, showers were installed at points where the base material passed about 5 minutes after leaving the water tank and immediately before the electrodeposition bath. The condition of spraying water by each shower was set to 0.5 to 1.0 L / min.

In this line, cationic electrodeposition coating is carried out using a bonnet of an automobile as a base material,
Bake for 0 minutes. No abnormal appearance was confirmed in the obtained cationic electrodeposition coating film.

Comparative Example A cationic electrodeposition coating film was obtained by the same procedure as in the example except that a shower at a point where the substrate passed about 5 minutes after leaving the water tank was not used on the same line as the example. Was. This coating film was visually confirmed to have a film thickness difference due to uneven drying of water.

[0017]

According to the cationic electrodeposition coating method of the present invention, water is sprayed a plurality of times after washing with water and before immersion in the electrodeposition bath. No poor appearance of the coating film. The cationic electrodeposition coating method of the present invention is effective when a drying oven is provided in the line but is not used, or when the substrate is a bonnet having many flat surfaces.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cationic electrodeposition coating method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Progress direction of line 2 ... Surface treated base material 3 ... Water tank 4 ... Dry oven not used 5 ... Electrodeposition bath 6 ... Shower 7 ... Shower 10 ... Cation electrodeposition coating line

Claims (3)

[Claims] 1. A cationic electrodeposition coating method in which a surface-treated substrate is rinsed by immersing the substrate in a water bath, and then the substrate is immersed in an electrodeposition bath to perform cationic electrodeposition. Water is sprayed a plurality of times from the time of performing to the time of immersion in the electrodeposition bath. 2. The cationic electrodeposition coating method according to claim 1, wherein one of said plurality of water sprays is performed immediately before immersion in said electrodeposition bath. 3. The cationic electrodeposition coating method according to claim 1, wherein the time from the water washing to immersion in the electrodeposition bath is 10 minutes or more.