There are two types of powder coatings—thermoplastic and thermosetting. When we apply thermoplastic powder coating ,it melts and flows when heat is applied but continues to have the same chemical composition after it cools and solidifies. So thermoplastic powders have excellent chemical resistance, flexibility and toughness and other characterristics . They are applied mainly by the fluidized bed application technique, in which heated parts are dipped into a vat where the powder is fluidized by air and are used in many thick film applications.
Thermosetting powder coatings are based on lower molecular weight solid resins which melt when exposed to heat. After they flow into a uniform thin layer, however, they chemically cross-link within themselves or with other reactive components to form a reaction materials of much higher molecular weight,which are heat stable and, unlike the thermoplastic products after curing, will not soften back to the liquid phase when heated. Thermosetting powders are derived from three generic types of resins:acrylic , polyester and epoxy. From these resin types, several coating systems are derived. Resins used in thermosetting powders can be ground into fine particles necessary for spray application and a thin film finish. Most of the advanced technology in recent years have been with thermosetting powders.
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