Can a liquid electrostatic spray gun be used on plastic products? Why?
First, we need to know why we choose an electrostatic spray gun?
The liquid electrostatic spray gun uses the force of an electrostatic field to make negatively charged paint particles stick to the surface of the workpiece. Compared to traditional spraying, this helps the paint adhere better to plastic surfaces, improving the coating’s adhesion and durability. At the same time, the electrostatic effect allows the paint to evenly cover complex shapes and curved plastic parts, resulting in a
smooth and uniform coating that effectively enhances the appearance and overall look of plastic products.
Overall benefits better meet production needs. The paint usage rate of liquid
electrostatic spray guns can reach 70%-90%, which can greatly reduce paint waste and lower the production cost of plastic coating. At the same time, it reduces paint mist dispersal and lessens environmental pollution, making it more in line with eco-friendly production requirements.
Note: Plastic itself is an insulator, so when using a liquid electrostatic spray gun to coat plastic products, you need to pre-treat the workpiece to make it conductive and ensure it's properly grounded (ground resistance less than 1 megaohm). At the same time, adjust the voltage,
spraying distance, and other process parameters according to the type of coating, and you can get a stable spraying result.
What conditions are needed for electrostatic liquid spray coating on plastic products?
1. Substrate and Conductive Pretreatment Conditions
First, perform an antistatic process. Use a corona discharge antistatic device to neutralize uneven charges on the plastic surface caused by friction, preventing static electricity from interfering with the coating process.
After conductive treatment, reduce the surface resistance of the plastic to <10⁸Ω by dipping, spraying, or rinsing with a conductive agent, or by applying a conductive primer, plasma surface treatment, etc. This establishes a stable electrostatic conductive path while ensuring the workpiece is well grounded, with a ground resistance of less than 2MΩ.
Also, make sure the surface is clean in advance—completely remove oil, dust, mold release agents, and other contaminants from the workpiece surface to avoid affecting coating adhesion.
2. Coating Performance Conditions
The paint's own resistance needs to be controlled within 10⁷Ω to ensure the paint spray particles can be properly charged. The application viscosity should be slightly lower than normal air spraying, which can be achieved by heating the paint to 40°C–60°C to reduce viscosity, improve atomization, and help the mist evenly deposit along the electric field.
3. Equipment and Environmental Conditions
Spray guns, workpieces, personnel, and the floor must all be securely grounded. Operators should wear conductive shoes, with body-to-ground resistance less than 1–2MΩ to prevent charge buildup and safety hazards.
The spray booth airspeed should be controlled at 0.5–0.7 m/s; too high a speed can interfere with electrostatic attraction. Also, ensure proper paint mist exhaust and explosion-proof facilities are in place.
