Zinc-rich primer metals include ferrous metals (such as steel) and non-ferrous metals (such as aluminum alloy), which need to be surface treated in order to prevent rust.
There are many methods of surface treatment, among which cathodic protection surface treatment is a common one.
In the cathodic protection process, zinc rich primer is used.
Zinc powder is a kind of chemical active raw material. The electrode potential of zinc is -0.7628V, and that of iron is -0.409V. In the paint film, the zinc powder contacts with each other and conducts electricity by contacting with steel.
Therefore, when the steel structure coated with zinc-rich primer is corroded, because the electrode potential of zinc metal is negative than that of iron in a wide temperature range, zinc is the anode, which is corroded, while iron is the cathode, which plays the cathodic protection role of sacrificing the anode.
At the same time, the products after zinc powder corrosion can fill the pores of the film, close the damaged part of the film, and play a role in shielding the corrosive medium.
Therefore, although the coating of zinc rich coating is relatively thin, it still has a good antirust effect and a long service life.
Film-forming substrates for zinc-rich primers often use organic resins such as epoxies, chlorinated rubbers, vinyl resins and polyurethane.
As early as 1962, it was found that zinc-rich primers prepared using partial hydrolysates of alkoxy silane (e.g., ethyl orthosilicate) or mixtures of alkali silicate and zinc powder provided better cathodic protection for iron substrates than organic resin-based zinc-rich primers.
However, the drawback of this technology is the short storage and application life of the paint.
After 12 years, it was found that the stability and overall performance of the zinc-rich primers were greatly improved by transesterification of silicate with organic polyols such as ethylene glycol or glycerol.
This innovation was one of the most widely cited organosilicon inventions of the period 1964-1985, having been cited 34 times.
The zinc-rich primer has excellent corrosion resistance and adhesion due to the introduction of Si - O bonding polymers.
Excellent weather resistance and heat resistance.
Acid ester, EPDM for ethylene propylene diene rubber, SBR for general purpose synthetic rubber.