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Powder coating have two major categories: thermosetting and thermoplastic. Thermosetting
varieties incorporated into the formulation of crosslinking agent. When the powder is
baked, it is reacted with other chemical groups in the powder to improve the performance.
Thermoplastic variety does not accept any additional reaction in the baking process, but
only flows out to the final coating. The most common polymers are used for polyester,
polyurethane, polyester, epoxy resin (hybrid), epoxy resin (epoxy) and acrylic acid.
Electrostatic spraying is the main adsorption force of electrostatic force, the rate of
powder powder depends mainly on the number of charged particles. The charged amount of
powder is proportional to the square of the particle size of the powder. Increase the
particle size, increase the amount of charged powder, the powder rate increased. But the
powder particle size should not be too big, the particle size is too large, large granular
powder of gravity over air dynamic and static electricity, powder coating in flight
process, due to the gravity effect did not reach the surface of the workpiece have already
fallen. On the contrary, powder rate is reduced. Powder is too fine charged to reduce the
efficiency of coating construction will fall, ultra-fine powder (particle diameter <10 m)
is basically not charged, while the powder is too fine to increase the difficulty of the
production of powder.
Most powder coating particle size ranges from 30 to 50 microns and TG
to about 200 degrees C. For such a powder coating, the film thickness greater than 50
microns of the UPS may be required to obtain an acceptable smooth film. This is considered
desirable or acceptable to the surface texture depending on the final product. Many
manufacturers actually want to have a certain degree of orange peel, because it has help to
hidden metal, in manufacturing defects occurred in the process, and the resulting coating
is not easy to show the fingerprint.
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