Prevention of oxidative degradation of ZnDTP by microcapsulation and verification of its antiwear performance

Prevention of oxidative degradation of zinc dialkyldithiophosphate (ZnDTP) is very important to prolong the antiwear performance of the engine oil. The microcapsulation of ZnDTP was attempted so as to isolate ZnDTP from peroxides in bulk lubricating oil during use. Microcapsulation allows for the isolation and protection of ZnDTP in bulk lubricating oil, and the ability to release control of ZnDTP at the contact surfaces. The protection of ZnDTP from oxidative degradation was evaluated by adding cumenhydroperoxide to the microcapsule-containing sample oil or by blowing NOx gas into the sample, followed by analysis with 31P NMR. The antiwear performance of the microcapsule-containing sample oil was studied using a 4-ball tribometer. It was confirmed that the microcapsulation of ZnDTP significantly reduced the oxidative degradation of ZnDTP additive, and antiwear performance was effectively maintained.