Generally speaking, after the injection molding of plastic parts is completed, surface treatment operations will be carried out, such as painting, screen printing and electroplating. These surface treatment operations are almost harsh on the appearance. Now I will give you a general description of some phenomena encountered in plastic painting for your understanding.

Phenomenon 1: Granulation

Cause: Dirt on the operation site and dust mixed with paint; The paint preparation time is too long, and copolymer particles are generated from the paint and curing agent; The oil output of the spray gun is too small and the air pressure is too high, resulting in poor paint atomization or the spray gun is too close to the object surface

2. Phenomenon: vertical flow

Cause: Too much thinner will make the paint viscosity too low and lose viscosity; The oil output is too large, too close to the object surface or the spraying operation is too slow; The amount of fuel injected each time is too much or too thick, or the interval of re injection is too short; Uneven surface, especially streamline, easy to flow

3. Phenomenon: orange peel

Cause: Too much curing agent will make the paint film dry too fast and react violently; The spraying air pressure is too high, and the paint film cannot wrinkle and level; The temperature at the operation site is too high to form paint film. 4. Phenomenon: Whitening

Cause: The temperature and humidity at the operation site are high, and the paint film reacts violently, which may combine with the moisture in the air and cause whitening; Too much curing agent and too thick at one time

5. Phenomenon: foaming

Original solid: compressed air and water are mixed on the paint film, the temperature of the operation site is high, and the paint dries too quickly; The material surface has high water content and high air humidity; One time spraying is too thick

6. Phenomenon: shrinkage

Cause: The primer or intermediate paint before the top coat is not completely dry

7. Phenomenon: wrinkling

Cause: the drying time is too short or the paint film is too thick; Improper selection of curing agent in primer or putty; Incomplete primer putty; When spraying the finish paint, one shot is too thick, the internal deep agent does not volatilize in time, and the exterior is dry, while the interior is not dry.