These antioxidants are mainly alkyl thiophosphates and carbamates of various metals (such as copper, zinc, molybdenum and antimony, etc.), which have certain antioxidant capacity. They are mostly used in internal combustion engine oils, mainly acting as anti-wear, anti-friction, anti-oxygen and extreme pressure. In particular, zinc dialkyl dithiophosphate (ZDDP) has good anti-oxygen and anti-corrosion properties and certain anti-wear and anti-extreme pressure properties. Since its inception, has been an essential component of engine oil and industrial oil, it can effectively prevent engine bearing corrosion, can inhibit the high temperature oxidation caused by the oil viscosity growth, thus in lubricating oil additives occupy an important position.
The antioxidant properties of different ZDDP (T202, T203, T204 and T205) injected into base oil with 0.25% mass fraction were investigated by rotating oxygen bomb method (SH/T0193). It can be seen that ZDDP series antioxidant has a good antioxidant effect in 125N base oil. T204 has good antioxidant effect in HVIW H150 base oil. In synthetic oil PAO6, ZDDP series of antioxidants have a good antioxidant effect. There are many kinds of organic copper salts, including organic copper carboxylate, copper thiophosphate, copper thiocarbamate, copper sulfide borate and so on. For example, dialkyl 2