JPH01296A - Electrodeposition coating method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electrodeposition coating method.

(Prior art) In the conventional electrodeposition coating method, the object to be coated is immersed in a paint tank to serve as an anode or a cathode, and a counter electrode is provided in the paint tank, or
Alternatively, painting is performed by forming a coating film by energizing the paint tank itself as a counter electrode.

(Problem to be solved by the invention) With the above method, a coating film is formed on the entire dipped coated product, so it is very difficult to partially coat the product. When it is necessary to paint, methods of immersing only a portion of the object to be painted in a paint tank or masking methods are considered, as described in JP-A No. 61-243196. .

However, in the method of dipping a part of the object to be coated, although it is possible to paint only the dipped part, it is not possible to paint the desired part at will. For example, it is not possible with this method to paint only the back side of the bumper. Furthermore, the method of applying masking is time-consuming and extremely difficult, especially when a large area of a large-sized painted product must be masked.

In addition, the conventional electrodeposition coating method requires a paint tank large enough to immerse the object to be coated, so when painting a thick object, a fairly large paint tank is required. Another problem is that a large facility space is required to install the device. Furthermore, when such a large paint tank is used, a large amount of paint is required, resulting in an increase in painting costs. For example, length 1m70c
When painting a m bumper using the conventional electrodeposition coating method, 2 m x 1 with approximately 100 z of paint applied.
There was a problem that a paint tank of m x 0.5 m was required, a large equipment space was required, and a large amount of paint was consumed, and an improvement was desired.

In addition, areas where corrosion resistance is partially poor due to residual oxide film, such as welded parts of shock absorbers, require a thicker coating to improve corrosion resistance, but conventional With the electrodeposition coating method, a coating film with a uniform thickness is formed over the entire object to be coated, so it has been impossible to thicken only a portion of the coating film.

Further, even when obtaining a coated product with a thick coating film overall, there is a problem in that it is necessary to extend the energization time, change the voltage, etc.

The present invention solves the above-mentioned problems, and even when painting a large product, partial painting is possible without requiring a large paint tank or a large amount of paint. The object of the present invention is to provide an electrodeposition coating method that allows coating to be thick.

(Means for Solving the Problems) In order to achieve the above object, the electrodeposition coating method of the present invention uses the object to be coated placed outside the paint tank as an anode or a cathode,
A coating film is formed by providing a counter electrode in the paint tank or by applying the paint in the paint tank to the object while applying electricity using the paint tank as a counter electrode.

The paint is supplied from the paint tank through the paint hose to the location of the object to be painted, and is applied to the area to be painted while electricity is applied to form a paint film. The paint hose preferably communicates with the paint tank via a valve.

Preferably, means is provided for collecting paint that has fallen off the painted surface after painting. More preferably, means for automatically returning and circulating the collected paint to the paint tank by means such as a pump is provided.

Coating by the method of the present invention involves wiring a cathode to the object to be coated, energizing it, opening the pulp and letting the paint flow out from the paint hose.
This paint is applied to the object to be painted, then washed with water and baked.

When partially painting, it is sufficient to apply the paint only to the desired area of the object.

When coating only one part to be thick, it is sufficient to apply the partial coating to the area where a thick coating is required, and then apply the entire coating using a normal electrodeposition coating method, that is, a full-deep coating method.

(Function) The electrodeposition coating method of the present invention coats the object by applying the paint outside the paint tank, so it is possible to partially coat the object, and only the negative part is thicker. It is also possible to apply a coating that looks like this.

(Examples) Hereinafter, the present invention will be explained in more detail based on Examples.

Embodiment 1: FIG. 1 is a diagram showing a coating apparatus 1 used in the coating method of this embodiment. The coating device 1 is equipped with a ball valve 3 at the bottom of a 50 x 50 x 30 cn+ vinyl chloride paint tank 2 placed at a height of 1.5 m from the floor. A paint hose 4 made of vinyl chloride with a diameter of 10 m is connected to supply the paint to the paint tank 2, and a SUS anode 5 of 20 CO+X20 CO1 is installed inside the paint tank 2. In the paint tank 2, 502 cationic electrodeposition paint (Ptu-80 black manufactured by Nippon Paint Co., Ltd.) is prepared.

Using the above coating equipment, the length lr is coated using the following method.
The back side of the r179cm chrome plated bumper 6 was painted. First, wire the cathode to the chrome-plated bumper 6,
A paint film was formed by applying a voltage of 250 V to the back of the chrome-plated bumper 6 by causing the paint to flow out of the paint hose while being energized.
It went for seconds. Thereafter, it was washed with water and baked at 170°C for 20 minutes. The coating film formed had a thickness of 3.15±5 μm.

Salt spray test (JISZ23) on painted bumpers
71) was carried out. For comparison, an unpainted bumper was used. After 240 hours, no red rust was observed on the bumper painted according to this example, but red rust occurred on the entire back side of the unpainted bumper.

Example 2: Shock absorber 7 was coated so that only the coating at the welded portion was thick.

First, as shown in Figure 2, the size of the anode 5° is loc
+++ Using the same coating apparatus 1' as in Example 1 except that the width was 10 cm, the absorber-lower seat weld 8 of the shock absorber 7 was coated by the following method. That is, first, 502 cationic electrodeposition paint (Ptu-80 black manufactured by Nippon Paint) was prepared in the paint tank 2, a cathode was wired to the shock absorber 7, and the voltage was set to 250V.
A paint film 9 was formed on the absorber-lower sheet welded portion 8 by applying the paint to the absorber-lower sheet welded portion 8 while applying a voltage of . Electricity was applied for about 60 seconds per location.

Thereafter, the entire shock absorber 7 was coated to a size of 50 x 50 x 75 cm using a conventional electrodeposition coating method.

It was immersed in a cationic electrocoating paint (Ptu-80 black) prepared in a paint tank (not shown) with a capacity of 1502 mm as a cathode, and a 30 cm x 30 cm SO5 anode was used as a counter electrode, and a voltage of 220 V was applied for 120 seconds. By applying electricity, a coating film was formed on the entire surface. After that, wash with water, 170
Bake at °C for 20 minutes. The thickness of the coating film formed is
As shown in Figure 3, only the welded part is thick, and the welded part is 20μ
m, and the other portions were 12 μm. For comparison, a coated product was manufactured in which the absorber-lower seat welded portion 8 was not partially coated, but only the entire body was dip coated using the above coating method. A salt spray test similar to that in Example 1 was conducted on the measured height and the comparative product, and the result was 8.
After 40 hours, no red rust occurred in the height measurement, but
Red rust occurred in the welded parts of the comparison product.

(Effects of the Invention) As described above, the electrodeposition coating method of the present invention involves painting while supplying the paint from a paint hose connected to a tank. Therefore, since a large paint tank and a large amount of paint are not required, the cost of painting can be reduced and the space of the painting equipment can be saved. In addition, because it is possible to apply partial coating or to apply a coating that is thicker in only one area, it has become possible to apply electrodeposition coating to objects that could not previously be applied with electrodeposition coating methods.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a coating device and an object to be coated used in one embodiment of the coating method of the present invention, and Fig. 2 is a diagram showing a coating device and an object to be coated in another embodiment of the invention. 3 is a diagram showing a coated article coated by this coating method. In the diagram, 1.1? ...Painting equipment 2...Paint tank 3...
Valve 4...Paint hose 5.5'...
・Anode 6...Bumper 7...Spot absorber 1st cause 2nd figure 3rd figure

Claims (1)

[Claims] The object to be coated placed outside the paint tank is used as an anode or cathode, and a counter electrode is provided inside the paint tank, or the paint in the paint tank is applied to the object while electricity is applied with the paint tank as the counter electrode. An electrodeposition coating method characterized by forming.