Introduction to the working principle of electrostatic plastic powder coating

Update:19 Feb,2021

1. What is electrostatic coating

The name of the static conductive paint is based on a series of national standards. The static conductive paint is used. From the industrial building and equipment design, the static conductive paint is used. From the function analysis of the paint, the paint can leak in a short time of 10-2 seconds. Accumulation of static voltage, to avoid accidents caused by electric discharge, fire alarm or destruction of electronic components, and the generation and accumulation of static electricity are objectively existing in nature, and there is no resistance skill. It is an antistatic agent product used for fabrics without measuring the theory of conduction leakage. , Can prevent the accumulation of static electricity in the clothing process.

2. Working principle of electrostatic coating

When working, the electrostatic spray gun or spray cup part is connected to the negative electrode, and the workpiece is connected to the positive electrode and grounded. Under the high voltage of the high-voltage electrostatic generator, the end of the spray gun (or spray plate, spray cup) and the workpiece are formed An electrostatic field. The electric field force received by the paint particles is directly proportional to the voltage of the electrostatic field and the charge amount of the paint particles, and inversely proportional to the distance between the spray gun and the workpiece. When the voltage is high enough, the area near the end of the spray gun forms an air ionization zone. Intense ionization and heat generate a dark red halo around the sharp edge of the spray gun or around the pole needle, which can be clearly seen in the dark. At this time, the air produces a strong corona discharge.

Most of the film-forming materials in coatings, such as resins and pigments, are composed of polymer organic compounds, which are mostly conductive dielectrics. In addition to film-forming materials, solvent-based coatings also include organic solvents, cosolvents, curing agents, electrostatic diluents, And other various additives and other substances.

Except for benzene, xylene, solvent gasoline, etc., most of these solvent substances are polar substances with low resistivity and certain conductivity. They can improve the charging performance of the coating. The molecular structure of dielectrics can be divided into polar molecules and non-polar molecules. A dielectric composed of polar molecules exhibits electrical properties when subjected to an external electric field; a dielectric composed of non-polar molecules exhibits electrical properties under an external electric field, thereby generating an affinity for external conductive charges, so that the dielectric is applied The outer surface can be locally charged in the electric field.

The paint is sprayed out after being atomized by the nozzle. When the atomized paint particles pass through the pole needle of the muzzle or the edge of the spray plate and spray cup, they are charged due to contact. When passing through the gas ionization zone generated by corona discharge, they will be Increase its surface charge density at one time. Under the action of the electrostatic field of these negatively charged paint particles, they move on the surface of the workpiece with guiding polarity and are deposited on the surface of the workpiece to form a uniform coating film.