JP2003306797A - Electrodeposition coating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method effective to prevent cratering in an electrodeposi tion system. <P>SOLUTION: In the electrodeposition system, a part of a water based solvent from at least a part of vessels in which the water based solvent is stayed is treated with an oil magnet filter and is returned to the vessels. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrodeposition coating system. In particular, the present invention relates to an electrodeposition coating system having a high cissing prevention effect.

[0002]

2. Description of the Related Art Electrodeposition coating can be applied to every detail even if it has a complicated shape, and it can be applied automatically and continuously. It is widely used as an undercoating method for objects to be coated, which has a complicated shape and requires high rust prevention. Further, compared with other coating methods, the use efficiency of the paint is extremely high, which is economical and is widely used as an industrial coating method.

The properties required for a coating film obtained by electrodeposition coating are:
That is, the coating film is smooth and has no surface defects such as pits and dents called cratering, and has high adhesion to the coating film formed thereon, and does not adversely affect smoothness and gloss. The defects called cissing are considered to be caused by volatile components and oils on the surface of the coating film or in the coating film, and they are caused by bumping at the time of baking or by forming through holes in the coating film when it volatilizes. There is.

In order to avoid the cissing phenomenon, the volatile components or oils that cause the cissing phenomenon should not be allowed to enter the coating film or the object to be coated, or the coating material itself should be modified by the materials or additives to be added to the coating material. The method by However, it is not possible to avoid the entry or mixing of the causative substance because various processes are required before coating, or because the coated product has a complicated shape and the oil content is unavoidable. is there. Various methods are being sought such as improvement of the material of the paint itself and examination of additives.

[0005]

The inventors of the present invention have improved the coating material itself and examined additives as described above.
In parallel with this, we have been studying a system for preventing cissing, including improving workability in an electrodeposition coating system.

Until now, an apparatus has been used for the purpose of removing the oil which causes cissing in the electrodeposition coating bath.
In the apparatus, as shown in FIG. 3, the paint overflowed from the electrodeposition coating bath 1 flows into the bubble removing tank 5, and the oil component floating on the upper surface of the electrodeposition coating material is collected in the bubble removing tank 5, where the oil absorbing material is collected. The oil floating on the surface was removed by using the above. The oil-removed paint is pumped for reuse in the electrodeposition bath 1.
I was returning it in the electrodeposition bath. Garbage mixed from the outside,
It was removed by a general filter provided on the way of returning it to the electrodeposition bath 1 by the pump 11. In addition, 2 in the figure shows an article to be coated.

According to this method, only a part of the oil component floating on the upper surface of the electrodeposition paint can be removed, and the removal efficiency is poor. Moreover, since the oil absorption is removed by floating an oil absorbing material such as a mat, it is labor intensive and the workability is poor. In the present invention, an alternative method has been found.

[0008]

That is, the present invention is characterized in that, in an electrodeposition coating system, a part of an aqueous solvent is applied to an oil magnet filter and then returned from at least a part of a tank in which the aqueous solution is retained. Regarding electrodeposition coating system.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 is a view schematically showing a mode in which an electrodeposition coating bath is passed through an oil magnet filter in the electrodeposition coating system of the present invention.

FIG. 2 is a schematic view showing steps of a general electrodeposition coating system.

FIG. 3 is a schematic diagram showing a method of removing oil from an electrodeposition coating bath that has been generally performed conventionally.

In the present invention, in any part of the electrodeposition coating system, at a part where the aqueous solution is retained, a part of the aqueous solution is passed through an oil magnet filter to remove oil. As shown in FIG. 2, an electrodeposition coating system generally consists of a pretreatment step in which several steps are combined, and basically four steps of an electrodeposition coating step, a water washing step and a baking step. The pretreatment step usually consists of steps of degreasing, washing with water, surface conditioning, chemical conversion treatment and washing with water. Of course I'm not stuck with this. In any of these steps, the treatment with the oil magnet filter of the present invention may be performed, but from the viewpoint of preventing cissing on the electrodeposition coating film, the most efficient is the electrodeposition coating step. Or a water washing step after the electrodeposition step. The oil magnet filter treatment of the electrodeposition bath during the electrodeposition coating step will be described below with reference to FIG. 1, but as described above, the oil magnet filter treatment may be added in various steps.

FIG. 1 is a diagram schematically showing a state in which an oil magnet filter is applied to the electrodeposition coating bath of the electrodeposition coating system of the present invention.

In the figure, 1 indicates an electrodeposition bath containing an electrodeposition paint. Reference numeral 2 denotes an object to be coated, which moves in the direction of the arrow and is immersed in an electrodeposition bath for electrodeposition coating, and then the process proceeds to the next step. Part of the electrodeposition paint flows into the bubble-removing tank 5 provided at the exit of the electrodeposition bath. The defoaming tank 5 is originally provided to collect and remove the foam generated in the electrodeposition bath 1. A part of the defoaming tank 5 is sent to the oil magnet filter (OMF) 3 by the pump 4. After processing, return to the electrodeposition bath. The oil magnet filter has a function of removing dust in the electrodeposition bath as well, but normally, as shown in FIG. 1, a general filter 6 is provided in parallel with the oil magnet filter to remove dust and the like. Is preferred.

The oil magnet filter is not particularly limited in its material as long as it has a purpose of adsorbing oil, but a back type such as a polyethylene material is preferable. As a product, UNIVERSAL FILTER, IN
C. The product number OS-29 of the company and WOSEP (trade name) [manufactured by Toray Industries, Inc.] are suitable.

The total circulation amount of the electrodeposition coating material on the oil magnet filter is approximately 1 when the electrodeposition bath is 100 tons.
It is sufficient to make a turnover in 6 to 10 times per hour. When the magnet filter becomes dirty due to use as described above, it is necessary to replace the filter. The replacement time may be a time when the repellency is increasing, but specifically, it may be considered to be 1 to 3 months.

[0015]

EXAMPLES The present invention will be described in more detail by way of examples. Example 1 An electrodeposition bath was constructed in the laboratory. A known amount of oil was put in the electrodeposition bath, electrodeposition coating was performed, and washing and baking were performed to cause cissing. The same paint was applied via the pump to the UNIVERSAL FILTER, INC.
4 for the oil magnet filter of the company's product number OS-29
Circulation was started at a rate of 1 L / min of L paint. The occurrence of cissing was reduced 0.5 hours after the start of circulation. After 1 hour, the cissing was very small.

[0016]

As is clear from the above examples, it can be understood that cissing can be effectively prevented by circulating the electrodeposition paint through the oil magnet filter of the present invention.
Of course, the method of the present invention can effectively prevent cissing by providing not only the electrodeposition coating bath, but also the water washing step before that or the step where the aqueous solution stays in any step of the electrodeposition coating system. it can.

[Brief description of drawings]

FIG. 1 is a view schematically showing a mode in which an electrodeposition coating bath is passed through an oil magnet filter in the electrodeposition coating system of the present invention.

FIG. 2 is a schematic view showing steps of a general electrodeposition coating system.

FIG. 3 is a schematic diagram showing a method of removing oil from an electrodeposition coating bath that has been generally performed conventionally.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrodeposition bath, 2 ... Coated object, 3 ... Oil magnet filter, 4 ... Pump, 5 ... Defoaming tank, 6 ... General filter.

Claims (5)

[Claims] 1. The electrodeposition coating system, wherein a part of the aqueous solvent is attached to an oil magnet filter and then returned from at least a part of a tank in which the aqueous solution is retained. 2. The electrodeposition coating system comprises pretreatment, electrodeposition coating,
The electrodeposition coating system according to claim 1, wherein the steps of washing with water and baking are performed in this order. 3. The pretreatment process includes degreasing, washing with water, surface conditioning,
The electrodeposition coating system according to claim 2, wherein the steps are chemical conversion treatment and water washing. 4. The electrodeposition coating system according to claim 1, wherein the aqueous solution applied to the oil magnet filter is an electrodeposition coating used in the electrodeposition coating process. 5. The electrodeposition coating system according to claim 1, wherein the aqueous solution applied to the oil magnet filter is washing water in a washing step after the electrodeposition coating.