JPH03111594A - Method for defoaming recovered washing liquid in coating system by electrodeposition and coating system by electrodeposition fitted with means to defoam recovered washing liquid - Google Patents

Abstract

PURPOSE:To vanish the foam on a recovered washing liq. and to automatically replenish the volatized thinner by forming a circulation path between a washing booth for washing a coated body and a tank and setting up a thinner sprayer in the tank. CONSTITUTION:A body 2 to be coated is coated with paint by electrodeposition in an electrodeposition vessel 1, sent to a washing booth 11 and washed by spraying with a liq. obtd. by filtering the paint in the vessel 1. At this time, the washing liq. foams up and is recovered in a tank 12. Thinner is sprayed from a sprayer 18 set up in the tank 12 on the foam layer on the washing liq. to vanish the foam and simultaneously the thinner is replenished.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention spray-cleans the object coated with paint in an electrodeposition tank, collects the cleaning liquid in a tank, and then uses the recovered cleaning liquid for spray cleaning. In an electrodeposition coating system in which excess paint is recovered by returning a portion of the paint to the electrodeposition tank while the paint is being used for general purpose purposes, bubbles generated in the tank during the spray washing process can be easily and reliably eliminated. The present invention relates to a defoaming method for recovered cleaning liquid in an electrodeposition coating system and an electrodeposition coating system equipped with a defoaming means for recovered cleaning liquid.

(Prior art) Electrodeposition coating has recently been widely used as a coating for electrical equipment storage boxes, etc. because it has the advantages of excellent film thickness uniformity, corrosion resistance, and throwing power. In electrocoating, there is a film of paint that physically adheres to the object being removed from the electrodeposition tank, in addition to the paint that is electrically attached to it. After that, the paint is passed through a water washing device to wash away excess paint, and after the paint is collected, it is returned to the electrodeposition bath, thereby making effective use of the paint.
(see publication). However, since the water washing equipment in this type of electrodeposition coating system normally uses recovered cleaning liquid to wash the object to be coated, foaming occurs, and the cleaning effect decreases due to the contamination of this foam, and the foam overflows from the tank. There have been various problems such as making cleaning work troublesome, deteriorating the working environment, and requiring wastewater treatment management (Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems. By solving the problem and eliminating the bubbles in the recovered cleaning solution during the washing process of electrocoating, we not only improved the cleaning effect, but also reliably prevented foam from overflowing from the tank. This was completed for the purpose of an electrodeposition coating system that is equipped with a defoaming method for the recovered cleaning liquid in an electrodeposition coating system that can replenish the thinner portion of the paint solvent in the deposition tank, and a means for defoaming the recovered cleaning liquid. .

(Means for Solving the Problems) The present invention, which has been made to solve the above-mentioned problems, uses a solution obtained by filtering the paint liquid in the electrodeposition tank to coat an object to be coated with a paint electrodeposited in an electrodeposition tank. In an electrodeposition coating system that performs spray cleaning and collects the cleaning liquid in a tank, and circulates and uses this recovered cleaning liquid for spray cleaning and returns a part of it to the electrodeposition tank, the surface of the recovered cleaning liquid in the tank is A first method for defoaming a recovered cleaning liquid in an electrodeposition coating system, which is characterized by spraying thinner to defoam floating foam in a tank and replenishing the thinner portion of the paint solvent in an electrodeposition tank. In an electrodeposition coating system for carrying out the first invention, a coating liquid obtained by filtering the paint liquid in the electrodeposition tank is applied to the object to be coated carried out from the electrodeposition tank in the latter stage of the electrodeposition tank. The washing equipment consists of a washing booth with a spray riser, a tank connected to this to collect the washing liquid, and a defoaming device that sprays thinner into the tank. A thinner spraying device and a circulation path for circulating the recovered cleaning liquid in the tank to the spray riser, and further, the required tank and the electrodeposition tank are configured to supply a part of the recovered cleaning liquid to the electrodeposition tank. A second invention provides an electrodeposition coating system equipped with a defoaming means for recovered cleaning liquid, which is connected by a conduit.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

(1) is an electrodeposition tank for electrodepositing paint on the object (2) to be painted, such as the body of an electrical storage box;
Electrodeposition of the paint is carried out using 2) as the negative electrode and the paint as the positive electrode, and the paint solvent contains about 3% thinner. (3) is a filtration machine connected to the electrodeposition tank (1), which feeds back the paint filtered by this filtration machine (3) to the electrodeposition tank (1), and sends the filtrate to the filtrate tank (4). ), and is then supplied through a pressure pump (5) to a washing device (6) at the last stage of a washing line arranged after the electrodeposition tank (1), where it is used as a washing liquid. (6) are three water washing devices that make up the water washing line, and the water washing device (6) is for step-by-step washing of the object to be coated (2) carried out from the electrodeposition bath (1). In the embodiment, there are three, first, second, and third. The third, second, and first water washing devices (6) are connected in series via an overflow pipe, and a pipe (6) connecting the first water washing device (6) and the electrodeposition tank (1) 7) is equipped with a pump (8), which circulates the recovered cleaning liquid for spray cleaning and returns a portion of it to the electrodeposition tank (1) to collect excess paint. Effective use is being made. As shown in FIG. 2, the water washing device (6) is a spray riser (1
The cleaning booth (11) is composed of a cleaning booth (11) provided with a cleaning solution (0) and a tank (12) for collecting cleaning liquid and circulating it to the spray riser (10).
The floor surface (13) and the tank (12) are connected by a pipe (15) with pulp (14), and the tank (12)
2) and the spray riser θω are also connected by a pipe (17) with a pump (16) to form a circulation path. Also,
Each tank (12) is equipped with a thinner spray device (18) that sprays thinner at a required concentration toward the surface of the recovered cleaning liquid.
is installed, and is configured to be activated at regular intervals by control of a timer (not shown), etc.
Function) With this structure, the paint is sequentially electrodeposited on the object to be coated (2) in the electrodeposition bath (1), and the electrodeposition is removed by the filtering device (3) and each washing device (6). The paint is efficiently collected and fed back into the electrodeposition bath (1) for effective use.In addition, in each water washing device (6), the object to be coated (2) is cleaned by the spray riser 0II). When this is carried out, the cleaning liquid foams and the cleaning liquid containing air bubbles is collected in the tank (12),
Although a bubble layer is formed on the surface of the recovered cleaning liquid, the bubbles are instantly extinguished by the thinner sprayed from the thinner spraying device (18), and the bubble layer on the surface of the recovered cleaning liquid can be eliminated. Moreover, since the thinner to be sprayed is the same as the thinner contained in the electrodeposition coating, the required tank (12) and the electrodeposition tank (1) are
When a part of the recovered cleaning liquid is replenished from the pipe (7) connecting the electrodeposition tank (1), the thinner content of the paint solvent in the electrodeposition tank (1) is continuously ejected and the diluted volatile matter is automatically removed. It will be possible to replenish the supply. In addition, by eliminating foaming in the recovered cleaning liquid in the tank (12), the valve (14) can be opened without any restrictions, and the cleaning booth (11)
This means that the accumulation of air bubbles on the floor surface (3) can be effectively prevented. Although three water washing devices (6) were installed in the example, it goes without saying that this number can be arbitrarily selected depending on the coating conditions. It is also possible to add a thinner spray device (18).
The type and concentration of the thinner used can be arbitrarily selected depending on the coating conditions.

(Effects of the Invention) As is clear from the above description, in the present invention, the cleaning booth and the tank are used as a circulation circuit, and a thinner spraying device is provided in the tank to eliminate foaming of the recovered cleaning liquid in the water washing device. This not only makes it possible to achieve high cleaning efficiency, it also reliably prevents foam from overflowing from the tank, making work management extremely easy. Even if the thinner contained in the paint solvent is volatilized and diluted by returning the part to the electrodeposition tank, this cyclic coating has the advantage of automatically replenishing this volatile content.

Therefore, the present invention contributes to the development of industry as an electrodeposition coating system that is equipped with a defoaming method for recovered cleaning liquid and a defoaming means for recovered cleaning liquid in an electrodeposition coating system that eliminates the problems in conventional electrodeposition coating systems. It is extremely large.

[Brief explanation of drawings]

Figure 1 is a schematic view showing an embodiment of the system of the present invention, and the second figure is a schematic cross-sectional view of the washing device. (1): Electrodeposition tank, (6): Washing device, (7): Electrodeposition Pipe line for supplying part of the recovered cleaning liquid to the tank, (10): Spray riser (
11): Washing booth, (12): Tank (18):
Thinner spray device.

Claims (1)

[Claims] 1. Spray cleaning the object to be coated with the paint electrodeposited in the electrodeposition tank using a liquid obtained by filtering the paint liquid in the electrodeposition tank, collect the cleaning liquid in the tank, and use the recovered cleaning liquid. In an electrodeposition coating system in which the cleaning liquid is recycled for spray cleaning and a portion is returned to the electrodeposition tank, thinner is sprayed onto the surface of the recovered cleaning liquid in the tank to defoam the foam floating in the tank. A defoaming method for a recovered cleaning liquid in an electrodeposition coating system, characterized in that the thinner portion of the paint solvent in the electrodeposition tank is replenished at the same time. 2. An appropriate number of water washing devices (6) are provided downstream of the electrodeposition tank (1) to spray wash the objects to be coated taken out from the electrodeposition tank (1) with a liquid obtained by filtering the coating solution in the electrodeposition tank. The water washing device (6) consists of a washing booth (11) with a spray riser (10), a tank (12) connected to this for collecting the washing liquid, and a spray riser (10) for collecting the recovered washing liquid.
a thinner spraying device (18) for defoaming that sprays thinner toward the circulation path that circulates through the tank (12) and the tank (12);
), and furthermore, the required tank (12)
and the electrodeposition tank (1) are connected to the electrodeposition tank (1) by a conduit (8) for supplying a part of the collected cleaning liquid. painting system.