Advancement of Rubber Technology for Tires: Silica Compounds for Low Rolling Resistance

Abstract

Synopsis: Studies suggest that a fuel efficient tire can reduce as much as about 57kg of CO₂ emission compared with a conventional tire. One of the representing technologies for realizing such fuel efficient tires is silica compounding technology. The critical benefit of silica compound is to improve a balance of rolling resistance and wet skid resistance of a tire, which are usually in trade-off relationship. In order to maximize such benefit, one needs to disperse silica in rubbery matrix well enough. Numerous methods have been developed for this purpose. In addition to the use of ordinary silane coupling agents, critical improvements were achieved by molecular designs of dispersion aid chemicals and tailormade polymers for better silica dispersion and silica-polymer reinforcement. On the other hand, technologies for material characterization and property prediction at nano-scale are advancing thanks to rapid progresses of analytical and simulation tools that can handle nano-scale phenomena. We are about to capture hierarchical nature of nanostructure of a compound in quantitative manner, and deepening our understanding about the mechanism behind the hysteresis loss of rubber compounds. By utilizing these designed materials and analytical/modeling technologies, tires that deliver the maximum balance of wet skid resistance and low rolling resistance have been developed and put in the today’s market.