The silicone resin powder
coating is a 100% solid powder coating. It is different from general solvent-based coatings and waterborne coatings. Instead of using a solvent or water as a dispersion medium, it uses air as a dispersion medium. It has the characteristics of no volatiles, easy to clean, no solvent, less damage to operators, high utilization rate of spraying and excellent performance. With the increasing global attention to environmental protection, the application of powder coatings is becoming more widespread. The use of powder coatings in China has exceeded 1 million tons.
Silicone resin high temperature resistant powder coatings are special functional coatings. Silicone resin high temperature resistant powder coatings are generally classified into 200 ° C, 300 ° C, 350 ° C, 400 ° C, 500 ° C and above depending on the temperature to which they are subjected. Silicone resin high temperature resistant powder coatings are widely used in barbecue ovens, crucible furnaces, heating machines, heating pipes, silencers, ovens, exhaust pipes for vehicles, chimneys and other equipment. Because of the advantages of high temperature resistant powder coatings in terms of environmental protection, safety, and utilization, it will gradually replace traditional high temperature paints. In recent years, due to the trend of "paint-to-powder", the market demand for temperature resistance of 500 ° C and above is increasing. In the application scenario of 500 ° C and above, the coating is directly subjected to the burning of an open flame, and the minimum requirement of the coating is to achieve no powdering and no falling off.
Formulation of silicone resin high temperature resistant powder coating
The formulation of powder coatings is mainly as follows: resin and its curing agent, which is the basis of coating film formation. Additive is to improve the appearance or performance of the coating. A pigment is that imparts opacity and color to the coating. The filler is mainly used for physical reinforcement.
When the commonly used saturated polyester resin, epoxy resin and other materials are above 350 °C, the carbon-oxygen bond will soon break and decompose, and the coating will be powdered and peeled off. Because of its silicon-oxygen bond as the main chain, silicone resin gives the silicone resin high oxidative stability due to its high bond energy, and is the first choice for high temperature powder coating host resin.
Fillers are the key to the performance of high temperature coatings. The filler should be selected for high stability and can react with the siloxane functional groups of the silicone resin. Therefore, silicate fillers are preferred, such as mica powder, silicon micropowder and so on. The other is the silicate material. They are mainly because their phosphates react with metals to ensure adhesion between the coating and the substrate. In terms of pigments, most conventional pigments cannot withstand temperatures above 500 °C. White can use titanium dioxide, black can be iron oxide black, iron manganese black, red yellow blue and other colors. It is recommended to use a package type product. The overall formulation ensures that heavy metals do not exceed the standard.
Production Process Control of Silicone Resin High Temperature Powder Coatings
The production process of high temperature resistant powder coatings is not much different from ordinary products. The process parameters need to be controlled mainly in the melt extrusion stage. Since the softening point of the silicone resin is low, it is necessary to control the proper extruder temperature to ensure the uniformity of the mixing during the melt extrusion stage. In the crushing stage, it is necessary to ensure that the particle size index is as narrow as possible. Because the coating of the high temperature resistant powder coating will have a certain degree of expansion when heated. The uniformity inside the coating is better, the possibility of expansion damage is lower.