The formula composition of powder coatings is mainly as follows: resin and its curing agent, which are the basis for coating film formation; additives, which are used to improve the appearance or performance of the coating; pigments, which contribute to the concealment and color of the coating; fillers, which are important It is the benefit of physical strengthening.
When the commonly used saturated polyester resin, epoxy resin and other materials are above 350 ℃, the carbon-oxygen bond will be broken very quickly. Because of its main chain of silicon-oxygen bond, silicone resin has high oxidative stability due to its high bond energy, and is the first choice for the main resin of high temperature resistant powder coatings.
Pigments and fillers are the links that affect the performance of high temperature resistant coatings. The fillers should be selected with high solidity and can react with the siloxane functional group of the silicone resin. Therefore, silicate fillers are the first choice, such as mica powder, silicon powder, etc. . In addition, there are silicate materials, which are mainly because their phosphate radicals can react with metals, thereby ensuring the adhesion between the coating and the substrate. In terms of pigments, most conventional pigments cannot withstand high temperatures above 500 °C. Titanium dioxide can be used for white, and iron oxide black, iron-manganese black, red, yellow and blue can be used for black. It is recommended to use packaged products. The overall formula is guaranteed Heavy metals will not exceed the standard.
High temperature resistant powder coating production process control
The production process of high temperature resistant powder coatings is not much different from ordinary products. The production process is in the table below. The most important place to control the process parameters is in the melt extrusion stage. Due to the low softening point of the silicone resin, it is necessary to control the proper extrusion. The temperature of the machine can ensure the uniformity of mixing in the melt extrusion stage. In the destruction stage, it is necessary to ensure that the particle size index is narrow, because the coating of the high temperature resistant powder coating will stretch to a certain extent when heated. The better the uniformity in the coating, the lower the possibility of stretch damage.
The function of high temperature resistant powder coating
Since the high temperature resistant powder coating is a functional coating, it is important to pay attention to its high temperature resistance performance. The high temperature resistance performance test adopts two methods to test. One is to determine the temperature test, and use a muffle furnace to subject the experimental board to a certain period of temperature. After baking, the effect of the board surface and the adhesion force are tested. The second is the actual use test, in which the paint is applied to the workpiece in use and tested for a certain period of time under actual use conditions.
High temperature resistant powder coating salt spray resistance
On the one hand, products such as barbecue grills and braziers require the coating to have temperature resistance, and on the other hand, they also need to have sufficient anti-erosion effect. In fact, consumers do not want to see rust and mottled when using. Therefore, the salt spray resistance of high temperature resistant powder coatings is also a key indicator.