Powder coatings are finely ground plastic particles consisting of resin,
crosslinker in thermoset powders, pigments & extenders, and various
flow additives and fillers to achieve specific properties. When they are
heated, these plastic particles melt to form a continuous film, typically
a very durable and chemical resistant film.
Powder coatings are applied as a dry material and they contain very
little, if any, Volatile Organic Compounds (VOC). The raw material is
literally a powder, mixed dry, extruded, and ground into the final material.
An environmentally safe coating that can provide a variety of
high quality finishes makes powder a popular alternative in the ecologically sensitive climate that we live in today.
Powder materials may be thermoplastic or thermoset.
Thermoplastic powders do not chemically react in a cure phase. They are typically used for functional applications and applied in thick films, typically 6–12 mils. They are used for a wide range of applications that require a tough finish with impact resistance and/or chemical resistance.
Thermoset powder coatings are applied and then cured in an oven at
a certain temperature for a certain time. The cure process will cause a
chemical crosslinking to take place, changing the powder into a continuous film that will not remelt.
Thermoset powders are used for a variety of functional and decorative applications and usually applied in thinner films, typically in a film thickness of 1.5 to 4 mils.
Powders can be formulated to meet a variety of appearance or performance characteristics. This would include the film thickness, gloss, texture, color, and performance (hardness, chemical resistance, U.V. Resistance, high temperature resistance, etc.) of the coating.
Powders are available with very smooth finishes, hammertones, wrinkles, and metallics.
A typical thermoset powder will have a resin as the primary film forming
component, several pigments for color, flow aids, and a cure agent.
The dry ingredients are blended at high speed to create a homogenous
mixture and then fed into an extruder for melt mixing.
The taffy-like extrudate is cooled and chipped. The chips are ground to a very specific particle size distribution and packaged for shipment.
The particle size is important to the performance and appearance of
the coating. Particle size can affect the application and appearance
characteristics of the coating.
Powder Coater's Manual 1/98
August 2, 2006