What is high temperature resistant powder coating

Update:25 Apr,2022
High temperature resistant powder coatings are mainly composed of high temperature resistant resins, high temperature resistant pigments, high temperature resistant fillers and special effect additives; they are widely used in chemical, petroleum, metallurgy, aviation and other industries due to their outstanding high temperature resistance. At present, heat-resistant powder coatings are still dominated by silicone powder coatings. The selection and control of each component in the indoor powder coating is the basis for the high temperature resistant silicone powder coating.

In high temperature powder coatings, silicone resins are indispensable. We know that silicone resins are mainly based on silicon-oxygen bonds. Due to their high bond energy, silicone resins have high oxidation stability and can be used in coating films A stable protective layer is formed on the surface. However, when silicone resin is used alone, the intermolecular force is relatively small, the adhesion is poor, and the price is relatively high. In the case of satisfying the correlation, it is generally necessary to add appropriate organic compounds to the resin. Silicone to solve the problem.

Silicone resin is an essential base material for high temperature resistant powder coatings. Silicone resin can be used alone as a base material or combined with polyester and epoxy resin to improve the high temperature resistance of the coating film. At the same time, high temperature resistant inorganic pigments and fillers and appropriate additives should also be selected in the formula. At present, the silicone resins used for high temperature powder coatings are mainly divided into the following two types:

Methyl polysiloxane, which is characterized by: good hardness; good hydrophobicity; low surface energy, non-stick effect; - good yellowing resistance at high temperature; but poor miscibility with other organic resins. Phenyl polysiloxane, good miscibility; good flexibility; gloss and color retention.

Generally, the curing temperature of silicone resin cannot be lower than 200 degrees. The temperature range between 270 and 350 °C is a sensitive range point for silicone high temperature powder coatings. Because at this time the silicone component has not been completely sintered, and the organic component has begun to burn and decompose.

In addition, the development of high Tg (glass transition temperature) silicone resins is also inevitable due to the caking problems encountered during storage and production and transportation of low Tg silicone resins. Now, the German Wacker Chemical Company has launched a Tg>65 silicone resin used in high temperature powder coatings, which has successfully solved the transportation and storage problems in high temperature weather.

Unlike organic resins, silicone resins used with appropriate pigments and fillers should have excellent long-term heat resistance (200 - 650 °C).

Additionally, for food contact applications, silicone resins should also comply with FDA 175.300 and BGVV – XV. Good heat and cold alternation. By immersing the hot plate directly in cold water, the coating film will not be damaged.