Influence of ZnO and Stearic Acid On the Hydrophobation Reaction of the Silica

The use of silica and silane in tire tread compounds gains more and more importance globally due to the upcoming tire regulations. The use of highly dispersible silica together with mercapto silanes like VP Si 363^® improves the rolling resistance by more than 10%. First investigations have shown that the mercapto-silanes react significantly differently with the silica compared to other silanes. The processing of such compounds becomes more difficult due to the required control of a chemical reaction during the mixing process. Therefore, optimum processing conditions have to be found to overcome these challenges.

This study was carried out to determine in detail the influence of ZnO and stearic acid as well as further rubber chemicals on the hydrophobation reaction of different silanes and especially of VP Si 363^®. The silica-silane reaction was investigated in a model system and compared with in-rubber results. The influence of the time of addition of ZnO and / or stearic acid on the hydrophobation reaction is one of the findings of this study.