The differences in powder coating come down to two chemical categories: thermoplastic and thermoset. Throughout this article, we will compare the two powder coating finishes discovering their respective pros and cons.
Thermoset powder coating is the most popular style in the industry, but thermoplastic is gaining popularity due to its performance and more environmentally friendly attributes. However, depending on the performance needed, thermoset’s thin and durable color may be more attractive compared to thermoplastic’s price and difficult application.
Thermoplastic.
Thermoplastic powder coating finishes become liquid and very soft when heated. This finish does not chemically bond to surfaces during the drying process. Rather, the coating is “fused” to the product using heat. This process makes the powder coating both reversible and reusable.
Some of the most common methods of applying thermoplastic coatings include:
Electrostatic Spray Application: The powder coating is electrically charged and is attracted to the metal product’s surface. The dry film and coated material are then heated in an oven, causing the powder to melt and flow.
Preheat Spray Application- The metal part is preheated. Then, powder coating is applied through a spray nozzle. The dry coating immediately melts and flows upon coming into contact with the heated surface.
Fluidized Bed Application (or dip coating)- Preheated parts are immersed in a hopper with a fluidized thermoplastic powder coating. The powder coating is attracted to and subsequently fuses to the preheated surface.
Thermoplastic coatings tend to be thicker, and hence more durable compared to thermoset coatings. For this reason, they can be used for a plethora of things from metal, auto parts, and even refrigerators. One of the most defining characteristics of thermoplastic coatings is their ability to be reheated, remolten, and re-solidified. Thus, allowing coating applicators to remove flaws that may have developed during the initial application.
Thermoset.
Thermoset powder is quite different in the fact that it forms chemical bonds once cured, making it safe from chips and crack, but impossible to recycle. This is because the bond prevents the coating from melting away. Likewise, thermoset coatings cannot be reworked, instead they burn when reheated.
Thermosets are solid resins that, when heated, melt, flow, and can crosslink with one another or other reactive substances to form compounds. During the thermoset powder coating process, the products surface is first heated to the desired temperature. Then, the powder coating is applied. Finally, the cooling process causes the coating to harden and gain strength.
One of the most significant developments in thermoset technology involves the capacity to engineer resin types with variable properties. This increased versatility provides more specific characteristics to each project including a range of colors, glosses, and surface finishes. Coating texture can be wrinkled, smooth, or matte, while film thickness is highly adjustable.
A Quick Pro & Con List.
While writing this article, many resources were used including Pinnacle’s powder coating experts. Other literature resources include: Corrosionpedia and Thomas Net.
