Introduction of electrostatic coating process parameters

During electrostatic painting, the performance of the sprayed coating has certain special requirements. For example, the resistance value of the coating should be controlled within a certain range (generally 5~50Ma). Well, at the coating construction site, it is generally necessary to measure the resistance value and electrostatic atomization characteristics of the coating.

1. Determination of resistance value

In electrostatic painting, in order to ensure good atomization and high painting efficiency, it is very important to check the resistance of the diluted paint. By measuring the resistance of the paint, it is controlled within the range required by electrostatic painting. In order to ensure a good atomization effect and coating efficiency during electrostatic coating, the method of measuring the resistance value is to use a resistance value measuring instrument. When measuring, insert the two electrodes into the adjusted coating according to the instrument instruction manual. Depth, when the power is turned on, the resistance value can be read directly from the dial, and the resistance between the two poles inserted in the paint can be directly measured with an insulation resistance meter (揺meter). The measured resistance value is volume resistance, and its unit is a/cm.

2. Determination of electrostatic atomization characteristics

Electrostatic atomization characteristics refer to the atomization performance and applicability of liquid coatings relying on electrostatic repulsion during electrostatic coating. It is related to the electrical characteristics and viscosity of coating. The instrument for measuring the characteristics of electrostatic atomization is called electrostatic atomization Tester, and its working principle is shown in Figure 3_2_6.

(1) Test process

Pour the paint to be tested into the cup, open the screw needle valve, and then the paint will pass through; the 0.1mm small hole will flow out in the shape of 11 quotients or protrude in a semicircle at the small hole. Turn on the high-voltage power supply, that is, form a high-voltage electrostatic field between the conical cup and the metal plate. Under the action of the electrostatic field, the paint droplets are atomized and attracted to the grounded metal base plate. According to the photocopy size and shape of the paint coated on the metal plate, the performance of the electrostatic atomization can be judged.

(2) Test conditions

The voltage is 40kv, and the time is 4s.

(3) Evaluation method

If the diameter of the photocopy reaches 30~40mm, the electrostatic atomization characteristics of the coating are considered qualified; if the diameter of the photocopy is small or the shedding paint is in a line shape, the electrostatic atomization characteristics of the coating are considered unqualified.