Cleveland Ohio Powder Coating: Thermoset Powder Coating

Thermoset materials are used for the majority of powder coating processes because they can provide a surface layer that is both durable and decorative. Most thermoset powders have a molecular weight lower than that of thermoplastic materials and higher than that of liquid coatings. Thermosets are solid resins that, when heated, melt, flow, and—unlike thermoplastics—can crosslink with one another or other reactive substances to form compounds with higher molecular weights. After curing, a thermoset coating remains thermally stable, meaning it cannot be melted back into a liquid from further heating.

In a powder coating system, the more brittle thermoset resins can be broken up into a very fine powder that can then be fabricated into an exceptionally thin, paint-like film. This film exhibits chemical and physical properties comparable to those of liquid-based coatings. In addition, advancements in thermoset technology have continuously increased the versatility of this material group, allowing for more customization options. Many standard thermoset materials can now be chemically altered to provide the specific characteristics required for a given application.

Thermoset Powder Coating Properties
The most commonly used thermoset powder coating resins derive from the epoxy, hydroxyl or carboxyl, acrylic, and silicone groups. They generally require lower curing temperatures than thermoplastics, and manufacturers often introduce additives to accelerate or delay the curing reaction. It is important to subject a powder-coated product to thorough heating and allow the thermoset to flow evenly over the targeted surface because once the thermoset powder has completed crosslinking, it cannot be reflowed to correct any flaws in the coating. To achieve successful coating results, it also necessary to match the thermoset formulation with the product’s intended corrosion resistance, curing cycle, texture, and aesthetic properties.

One of the most significant developments in thermoset powder coating involves the capacity to engineer resin types with variable properties designed to complement metal finishing treatments. This broader range of characteristics has led to an increase in specialized roles for thermoset powders, with polyesters and acrylics finding greater use in the automotive and appliance industries despite the traditional reliance on epoxy-based coatings. Most thermoset powders can provide a high level of corrosion, temperature, and impact resistance. They can also be designed with a wide range of colors, glosses, and surface finishes. Coating texture can be wrinkled, smooth, or matte, while film thickness is highly adjustable.

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