Silicone resin--Zinc-rich primer
  Metals include ferrous metals (such as steel) and non-ferrous metals (such as aluminum alloys, etc.). In order to prevent rust, they must be surface treated. There are many surface treatment methods, and cathodic protection surface treatment is a commonly used method. In the cathodic protection process, a zinc-rich primer is used. Zinc powder is a chemically active material. The electrode potential of zinc is 0.7628V, and the electrode potential of iron is 0.409V. In the paint film, the zinc powder contacts with each other and with steel to conduct electricity. Therefore, when the steel structure coated with zinc-rich primer is corroded, because the electrode potential of metallic zinc in a wide temperature range is negative than that of iron, zinc is the anode and is corroded, and iron is the cathodic protection and acts as a sacrificial anode. Cathodic protection. At the same time, the product of zinc powder corrosion can fill the pores of the coating film, seal the damaged part of the coating film, and play the role of shielding the corrosive medium. Therefore, although the coating of zinc-rich paint is relatively thin, it still has a good anti-rust effect and a long service life.
The film-forming base of zinc-rich primers often uses organic resins, such as epoxy resins, chlorinated rubbers, vinyl resins, and polyurethanes. As early as 1962, it was discovered that a zinc-rich primer prepared using a partial hydrolysate of alkoxysilane (such as ethyl orthosilicate) or a mixture of alkali metal silicate and zinc powder can provide a good effect on iron substrates. The cathodic protection performance is better than the organic resin-based zinc-rich primer. However, the disadvantage of this technology is the short shelf life of the paint and the short pot life during use. After 12 years, it was discovered that the stability and overall performance of the zinc-rich primer obtained through the transesterification reaction of silicate and organic polyols (such as ethylene glycol or glycerol) were greatly improved. This innovation was one of the most widely cited silicone inventions from 1964 to 1985, and has been cited 34 times. Because the zinc-rich primer introduces Si-O bond polymer, it has good corrosion resistance and adhesion; excellent weather resistance and heat resistance.