Powder coatings have a tendency to agglomerate at a certain temperature, which is mainly caused by the softening of materials such as resins and leveling agents in the coating when heated. Thermosetting powder coatings are organic polymers with low molecular weight resins.
This kind of resin itself has a physical property. At a lower temperature, a hard and brittle glass state will appear. When the temperature rises to a certain level, the resin will transform into a state with certain elasticity and adhesion. , Below this temperature, the resin returns to the glass state, and the temperature at which the glass state and the viscoelastic state of the resin transform each other is called the glass transition temperature of the resin.
When the powder coating is sprayed, the input air pressure should not be too large, and it is generally better to control it at 0.5-1.5kg/cm2. Too much air pressure will cause poor pattern definition or some pitting. The electrostatic voltage should not be too high, generally controlled at around 60-70Kv.
If the voltage is too high, the powder attached to the surface of the workpiece will rebound and cause pitting. Defects such as poor leveling. When spraying powder, pay attention to ensure the thickness of the coating film. Generally, it can be controlled between 70-100 μm to form obvious patterns and larger patterns. Defects such as exposed bottom.
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