Technical Notebook: High surface area, highly dispersible silica for tire tread applications

Precipitated silica use is known to improve tire performance by increasing wet traction and reducing rolling resistance, while maintaining wear life. Balancing these properties called the “magic triangle” requires using high-performance materials and optimizing rubber compound mixing.

A highly dispersible silica (HDS) is one key ingredient. We previously commercialized a CTAB ~160 m2/g surface area HDS for passenger car radial (PCR) tire treads: Eecosil-brand350MG. The current need is for a silica for high performance passenger car, truck/bus and electric vehicle tire treads.

Now, we have commercialized the high surface area (HSA) Eecosil 230MG highly dispersible silica that was developed in our pilot plant, scaled up into production to form Eecosil 230G, and successfully transferred to the highly dispersible finishing line equipment. Compounds were evaluated in our new rubber mixing and testing lab established to complement our comprehensive silica testing facility.

In a model PCR tread, Eecosil 230MG performs equivalent to commercial HSA HDS products. The M300/M100 reinforcement index value, which serves as one indicator of the effectiveness of the silica-silane hydrophobation and polymer coupling reactions is increased 10 percent by using Eecosil 230MG.

Dynamic mechanic testing shows tan delta values @0°C and @60°C (lab predictors of wet traction and rolling resistance) are improved 3 percent and 6 percent, respectively. SEM @100X magnification using ImageJ software analysis shows excellent dispersion of Eecosil230MG into desirable reinforcing aggregates with no agglomerates >23 microns, a result potentially important to improving tire wear life.

Current development efforts are to extend our reinforcing silicas for tire treads by beginning with rice husk ash instead of the traditional crystalline sand.