The electrostatic fluidized bed dipping method is a coating method that combines the fluidized bed dipping method and the electrostatic powder spraying method. The basic principle of coating is shown in Figure 5-7. Many electrodes are installed under the porous plate of the fluidized bed in the fluidized bed dip coating method. When the high-voltage direct current is connected to the electricity, the air in the fluidized bed is charged due to ionization. When the charged air ions collide with the powder coating, a transfer of charge occurs to charge the powder coating. At this time, the powder coating is negatively charged, and the object to be coated is grounded to be positively charged. Due to the electrostatic attraction, the powder coating is adsorbed to the object to be coated. When the object to be coated is machine-baked, it is sprayed with thermoplastic powder coating, which only needs to be melted and leveled; The particle size distribution of the powder used in electrostatic fluidized bed dip coating requires 20~100μm, and the voltage range used is 30-l20KV.
The electrostatic fluidized bed dip coating method has the following advantages:
① The object to be coated does not need to be preheated, and can be directly dip-coated by electrostatic fluidized bed;
② The loss of paint during painting is very small, and the utilization rate of paint is very high;
③ The investment in coating equipment is very small; no powder coating recovery equipment is required;
④Easy to realize automatic continuous coating;
⑤ The thickness of the coating film is easy to control, and it is suitable for the coating of thin coating films below 150 μm. The electrostatic fluidized bed dipping method has the following disadvantages:
①The coating voltage is very high, and the safety is poor;
②It is not suitable for painting large objects to be coated, but only suitable for painting small objects;
③Not applicable to the coating of coating film over 150µm.
Powder coatings suitable for electrostatic fluidized bed immersion coating include epoxy, polyethylene, polypropylene, cellulose acetate, chlorinated polyether, polyphenylene sulfide and other powder coatings. This coating method is mainly used in the mass production of small items, such as the coating of small motors, capacitors, resistors, metal wires, metal meshes, springs, etc.
