Explanation of high temperature resistant powder coatings

Update:02 Mar,2022
High temperature resistant powder coatings generally refer to coatings that do not change color or drop when the coating film is above 200 °C, and can still maintain proper physical properties. Under normal circumstances, 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, kerosene, metallurgy, aviation and other majors because of their outstanding high temperature resistance. Now heat-resistant powder coatings are still dominated by silicone powder coatings.

Silicon-oxygen bond is the main chain in silicone resin, because of its higher bond energy, it gives silicone resin higher oxidation stability, and can form a stable protective layer on the surface of the coating film. The use of silicone resin alone has small intermolecular force, poor adhesion, and high cost; under the condition that the relevant functions are met, a moderate amount of silicone resin is usually added to the resin to deal with the temperature resistance problem.

High temperature resistant powder coatings, within certain limits, the greater the amount of silicone resin added, the longer the application life of the coating film and the longer the response to heat resistance. It is mentioned in the literature that when the dosage of a certain silicone resin is increased from 0.1 to 0.3, the heat resistance time of the coating film increases from about 50h to 100h.

The heat source of industrial high temperature environment is mainly the combustion of various fuels (such as coal, kerosene, natural gas, gas, etc.), and the rolling debate of machines (such as electric machines, machine tools, grinding wheels, chainsaws, etc.), so that the machine can generate heat and partial heat. hot chemical reaction. Generally speaking, the material is resistant to heat above 250 ℃. At this time, the material cannot be used and protected very well, and the obstruction of thermal energy explosion will be inestimable.

The formula composition of high temperature resistant powder coatings is mainly as follows: resin and its curing agent, which is the base for coating film formation; additives, used to improve the appearance or performance of the coating; pigments, which impart concealment and color to the coating; fillers , the most important thing is to play the role of physical enhancement.

When the commonly used saturated polyester resin, epoxy resin and other materials are above 350 ℃, the carbon-oxygen bond will be broken and disassembled very quickly, and the coating will be pulverized and scattered. Silicone resin has high oxidative stability due to its high bond energy due to its silicon-oxygen bond as the main chain, and is a good 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 stability 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-based materials, which are mainly because their phosphate groups 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 guarantees heavy metals will not exceed the standard.