High temperature resistant powder coatings are mainly composed of high-temperature resistant resins, high-temperature resistant pigments, high-temperature resistant fillers, and special additives; Due to its outstanding high temperature resistance, it is widely used in industries such as chemical, petroleum, metallurgy, and aviation. At present, heat-resistant powder coatings are still mainly based on organic silicon powder coatings. The selection and control of various components in organic silicon powder coatings are the basis for making high-temperature resistant organic silicon powder coatings.
1. Application of Organic Silicon Resin in High Temperature Resistant Powder Coatings
The silicon oxygen bond is the main chain in silicone resin, which endows the silicone resin with high oxidation stability due to its high bond energy, and can generate a stable protective layer on the coating surface. However, when using silicone resin alone, the intermolecular forces are small, the adhesion is poor, and the price is also high; On the premise of meeting relevant performance requirements, it is generally recommended to add moderate amounts of silicone resin to the resin to solve the above problems.
The larger the amount of silicone resin added within a certain range, the longer the service life and heat resistance time of the coating film. 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 50 hours to 100 hours.
Of course, the actual dosage of different silicone resins needs to be determined experimentally.
2. Selection of color fillers
Due to the superior heat resistance of inorganic pigments compared to organic pigments, organic pigments are generally not considered in high-temperature resistant powder coatings, and suitable and stable performance are mainly selected from inorganic pigments; According to relevant literature, the impact resistance of the coating before baking in fillers is ranked from good to poor as follows: wollastonite, mica powder, kaolin>silicate>quartz. Mica powder is best after grilling, with little else.
In addition, the amount of pigment and filler also has a certain impact on the temperature resistance. The optimal range of its dosage is determined to be between 60% and 100% (compared to the resin problem) in the application of silicone resin heat-resistant powder coatings.
3. Selection of additives
Choosing appropriate additives is also an important part of improving the high temperature resistance and mechanical properties of high-temperature resistant powder coating coatings. Adding antioxidants, hardening agents, etc. to high-temperature resistant powders.