JP2000064094A - Electrodeposition coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and excellently electrodeposit a coating film on the outer surface of a material to be coated and on the intricately shaped part. SOLUTION: A material to be coated formed with an intricately shaped part is held by a holding electrode and dipped in a cleaning soln. stored in a cleaning tank, and then an ultrasonic vibration is transmitted from an ultrasonic vibrator dipped in the cleaning soln. to clean the material. The cleaned material is dried and subjected to electrodeposition coating. A solvent the same as a solvent contained in a soln. of a coating material for the material is incorporated into the cleaning soln. The material held by the holding electrode is dipped along with the holding electrode in the soln. of an electrodeposition coating material stored in the tank to a necessary level. A voltage is applied to the electrode inserted into the storage tank to supply a current to the material through the contact part with the holding electrode, and a coating film is electrodeposited on the material surface in a specified thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating method capable of satisfactorily coating even a complicated shape portion such as a bag hole, a groove or a through hole formed on an object to be coated.

[0002]

2. Description of the Related Art A rust preventive is applied to an article (painted object) such as a stator core of a motor, which may cause deterioration of durability or failure if rust is generated on its surface over time. For this reason, measures are generally taken to coat the surface of the article with a resin coating by an electrodeposition coating method.

In the above electrodeposition coating method, a solution in which an electrodeposition coating material (resin) is dissolved is stored in a storage tank at a required level, and an object to be coated held by a holding electrode is immersed in the solution. Then, by applying a predetermined voltage to the electrode facing the storage tank, the object to be coated is energized through the contact portion with the holding electrode, and the surface of the object to be coated is coated with a resin film with a predetermined thickness. Is electrodeposited.

[0004]

The photograph of FIG. 5 shows a state in which the article 10 to be coated has been subjected to electrodeposition coating. As shown in the photograph, the article 10 is covered with a bag hole, a groove or a groove. In the case where a complicated shape portion 12 (blank hole in the figure) such as a through hole is formed, the coating may not be electrodeposited on the complicated shape portion 12.
It is considered that this is because air bubbles or cleaning liquid in the cleaning process performed before coating remains on the complicated shape portion 12, or degreasing is not sufficiently performed in the complicated shape portion 12.

As a method for coping with the above problem, it has been proposed to apply ultrasonic vibration to the electrodeposition solution while the article to be coated 10 is immersed in the electrodeposition solution. That is, the ultrasonic waves are adhered to the complex-shaped portion 12 of the object to be coated 10 due to cavitation at the time of generation of ultrasonic waves from the ultrasonic vibrator immersed in the electrodeposition solution, particularly pressure and mechanical vibration when bubbles disappear. It is intended to separate and remove air bubbles and cleaning liquid. However, when ultrasonic vibration is applied during the electrodeposition coating, as shown in the photograph of FIG. 6, although the coating is electrodeposited on the complex shaped portion 12, a large number of dents are formed on the flat outer surface of the object to be coated 10. 14 was generated, and the background was exposed at the portion of the depression 14, which was a problem. It is considered that the above-mentioned cavitation at the time of generation of ultrasonic waves adversely affects the electrodeposition of the coating on the outer surface of the object to be coated 10.

[0006]

Accordingly, the applicant of the present application has conducted extensive studies to solve the above-mentioned problems, and as a result, degreasing complex shaped parts by ultrasonically cleaning an object to be coated before performing electrodeposition coating. It was carried out sufficiently, and it was discovered that bubbles and cleaning liquid did not remain adhered to the complex shaped portion due to this degreasing.

That is, the present invention has been proposed in view of the above-mentioned drawbacks inherent in the above-mentioned conventional technique, and has been proposed to suitably solve the above-mentioned drawbacks. It is an object of the present invention to provide an electrodeposition coating method capable of reliably and satisfactorily electrodeposition.

[0008]

[Means for Solving the Problems] Overcoming the above-mentioned problems,
In order to preferably achieve the intended purpose, the electrodeposition coating method according to the present invention is a method of applying an ultrasonic solution to a cleaning liquid in which an object to be coated is washed, and then cleaning the object to be coated with a solution of the electrodeposition coating solution. It is characterized in that it is dipped in the inside to perform electrodeposition coating.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the electrodeposition coating method according to the present invention will be described below with reference to preferred embodiments.

FIG. 1 is a flow chart showing the steps of the electrodeposition coating method according to the embodiment. First, as shown in FIG. 2, an object to be coated 10 on which a complex shaped portion 12 such as a bag hole is formed.
In a state of being immersed in the cleaning liquid 20 held by the holding electrode 16 used in the electrodeposition coating process and stored in the cleaning tank 18, ultrasonic vibration is oscillated from the ultrasonic vibrator 22 immersed in the cleaning liquid 20, The object to be coated 10 is ultrasonically cleaned. By this ultrasonic cleaning, degreasing of the complicated shape portion 12 is surely performed. After the object to be coated 10 that has been cleaned is dried with a dryer or the like, or is naturally dried, the cleaning liquid is drained, and then the electrodeposited coating process is performed. The cleaning liquid 20 is a mixed liquid of water and a solvent, and as the solvent,
The cellosolve-based solvent is blended at a ratio of 10 wt%. This cellosolvable solvent is the same as the solvent contained in the solution of the coating material to be coated on the article 10 in the electrodeposition coating process. That is, by making the solvent of the paint and the solvent of the cleaning liquid 20 the same, the wettability between the object to be coated 10 and the paint can be improved.

Next, the washed object 10 is subjected to electrodeposition coating. That is, as shown in FIG. 3, the object 10 to be coated held by the holding electrode 16 is dipped in a solution 26 of the electrodeposition coating material stored in a storage tank 24 together with the holding electrode 16 at a required level. Then, by applying a predetermined voltage to an electrode (not shown) facing the storage tank 24, electricity is applied to the object 10 to be coated through the contact portion with the holding electrode 16 to cause the object 10 to be coated. A coating is electrodeposited on the surface of 10 with a predetermined thickness. In this case, the object to be coated 10 is sufficiently degreased by the action of ultrasonic vibration during the cleaning in the previous step, and the wettability with the paint is improved, so that the complex shape part 12 is surely coated with the film. (See FIG. 4). The object 10 to be electroplated is washed and then baked and hardened in a furnace.

[0012]

[Test Example] As in the above-described embodiment, for the object to be coated (specifically, the stator core material) 10 that has been ultrasonically cleaned and then electrodeposition coated, the application time of ultrasonic vibration during cleaning and unpainted The following table shows the results of the inspection of the relationship with the defective rate. The test results are shown by the ratio of the number of unpainted parts to the whole of the five objects 10 to be coated on which the complicated shape parts 12 are formed. The ultrasonic vibration was performed under the conditions of a frequency of 40 kHz and an output of 300 W.

[0013]

That is, from this test result, by applying ultrasonic vibration for 10 seconds or more in the cleaning step,
It was revealed that the unpainted defective rate was significantly improved.
By applying ultrasonic vibration for 60 seconds or more,
It was confirmed that almost 100% of the unpainted part could be eliminated.

The frequency and output of ultrasonic vibration can be arbitrarily set according to the size and number of objects to be coated. The object to be coated is not limited to the stator core of the motor, but can be suitably used for all parts having a plurality of shapes. Further, the solvent to be mixed in the cleaning liquid may be any solvent contained in the solution of the electrodeposition coating composition, and is not limited to the cellosolvable solvent of the examples.

[0016]

As described above, according to the electrodeposition coating method of the present invention, the coating film is surely electrodeposited on the complicated shape portion such as the bag hole, groove or through hole formed on the object to be coated. be able to. Moreover, the coating can be uniformly electrodeposited on the entire surface of the object to be coated without causing defects such as dents on the flat outer surface.

[Brief description of drawings]

FIG. 1 is a flowchart showing steps of an electrodeposition coating method according to a preferred embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a step of ultrasonically cleaning an object to be coated.

FIG. 3 is an explanatory view showing a process of electrodeposition coating an object to be coated.

FIG. 4 is a photograph of an object to be coated which is electrodeposited by the electrodeposition coating method according to the embodiment.

FIG. 5 is a photograph of an object to be electrodeposition coated by an electrodeposition coating method according to a conventional technique.

FIG. 6 is a photograph of another object to be electrodeposited while applying ultrasonic vibration.

[Explanation of symbols]

10 Painted object 20 cleaning liquid 26 solutions

Claims (2)

[Claims] 1. A cleaning liquid (20) in which an article to be coated (10) is immersed is washed by applying ultrasonic vibration, and then the article to be coated (10) is immersed in a solution (26) of an electrodeposition coating composition. The electrodeposition coating method is characterized in that the electrodeposition coating is performed. 2. The cleaning solution (20) is a solution (2) of electrodeposition paint.
The electrodeposition coating method according to claim 1, wherein the solvent contained in 6) is mixed.