PCB Blog - Electrostatic spray coating service

Electrostatic spraying is a spraying method that utilizes a high-voltage electrostatic field to cause negatively charged coating particles to move in the opposite direction of the electric field and adsorb the coating particles on the surface of the workpiece. One coat can obtain a thicker coating. The spraying equipment consists of a spray gun, a spray cup, and a high-voltage power supply for electrostatic spraying.

operational principle

When working, the spray gun spray disc or spray cup for electrostatic spraying is connected to the negative electrode of the coating particles, and the workpiece is connected to the positive electrode and grounded. Under the high voltage of the high-voltage power supply, an electrostatic field is formed between the end of the spray gun (or spray disc or spray cup) and the workpiece. The electric field force received by coating particles is directly proportional to the voltage of the electrostatic field and the charged amount of the coating particles, and inversely proportional to the distance between the spray gun and the workpiece. When the voltage is high enough, an air ionization zone is formed near the end of the spray gun, causing intense ionization and heating of the air, forming a dark red halo around the sharp edge or electrode of the spray gun, which can be seen in the dark. At this time, the air generates a strong corona discharge.

The film-forming substances in coatings, such as resins and pigments, are mostly composed of polymer organic compounds and are mostly conductive dielectrics. In addition to film-forming substances, solvent-based coatings also contain organic solvents, cosolvents, curing agents, electrostatic diluents, and other various additives. These types of solvent substances, except for benzene, xylene, solvent gasoline, etc., are mostly polar substances with low electrical resistivity and certain conductivity, which can improve the charging performance of coatings.

The molecular structure of dielectrics can be divided into two types: polar molecules and non-polar molecules. A dielectric composed of polar molecules exhibits electrical properties when subjected to an external electric field; The dielectric composed of nonpolar molecules is external.

The coating is sprayed out after being atomized by a nozzle, and the atomized coating particles are charged due to contact when passing through the electrode needle or the edge of the spray disc or cup. When passing through the gas ionization zone generated by corona discharge, it will once again increase its surface charge density. Under the action of the electrostatic field of these negatively charged coating particles, the polarized workpiece surface moves and is deposited on the workpiece surface to form a uniform coating film.

Application area 

1. Coating field: Electrostatic spraying is a common industrial spraying method widely used in industries such as automobiles, aviation, and motorcycles. This spraying method can improve spraying efficiency, save raw materials, have high coating quality, and have strong reliability.

2. Spray powder field: Electrostatic spraying can be used for spraying surface coatings on metal products, wood products, and other related products. It can spray various types of powder coatings, such as polyester, polyurethane, epoxy resin, acrylic acid, etc. This spraying method can increase the service life of the product and improve the appearance quality.

3. Pharmaceutical field: Electrostatic spray can be used in the pharmaceutical industry to prepare fine particles, nanoparticles, etc. This technology can improve the efficiency of drug absorption and improve treatment effectiveness.

4. Optoelectronics field: Electrostatic spraying can spray anti-corrosion coatings on electronic components such as transistors and circuit boards to the surface. This method can improve the service life of electronic products and protect the functionality of electronic components.

5. Other industries: Electrostatic spraying can also be used for coating work in industries such as wallpaper, daily necessities, toys, and medical devices. This technology can improve the aesthetics, service life, and performance of products.

Electrostatic spraying is a new type of spraying technology that uses an electric field to guide static charges onto coating particles, causing them to present the same charge, and then adsorbing it onto the sprayed object to form a uniform and smooth coating. Compared with traditional coating methods, electrostatic spraying has the advantages of fast speed, energy and material conservation, and high coating quality, which has been widely used in many industries.