Powder coatings after high temperature baking or sunlight will occur aging, yellowing and other phenomena seriously affect the appearance and performance of the product, in order to prevent or reduce the occurrence of this trend, usually use the addition of antioxidants or heat stabilizer to achieve. Although there are many factors that affect the aging of the coating film, such as the quality and type of resins, pigments, additives, coating formulation design, production process, temperature, atmosphere, humidity and other natural factors, the application of appropriate additives does reduce the occurrence of this trend.

Antioxidants are substances that inhibit or delay the oxidative degradation of polymers.

There are many varieties of antioxidants, and their effects are not the same, which can be divided into two categories according to their mechanism:

A. called chain-terminating antioxidants, such antioxidants react with free radicals produced in polymers to interrupt the growth of the chain, also known as main antioxidants;

B. Preventive antioxidants, which can inhibit or slow down the generation of free radicals in the initiation process, also known as auxiliary antioxidants. The main antioxidants are hindered phenols, pararylamines, auxiliary antioxidants are phosphite esters, metal dithiocarbamate salts and so on.