Tire rubber is a complex mixture of polymers, including natural and synthetic rubber, and filler. Traditionally, makers have reinforced their tire rubber with carbon black, which adds material strength. More recently, they began incorporating silica, which has the ability to enhance fuel efficiency and wet grip at the same time. Today silica is a common filler ingredient in fuel-efficient tires.
However silica's hydrophilic properties make it difficult to blend with rubber, which is primarily lipophilic, and this has imposed a limit on the amount of silica that can be added to tire rubber. Moreover, if the silica is not evenly blended in the rubber, deformation of the tire during operation can cause silica particles to rub against one another, producing heat from friction and negating the fuel efficiency benefits.
To address this challenge, Kao joined forces with Bridgestone, uniting our expertise in interface control with Bridgestone's NanoPro-Tech polymer technology to develop a new silica dispersion improver that dramatically improves affinity between the rubber and the silica. This agent allows uniform micro-dispersion of larger amounts of silica in the tire rubber for tires that combine advanced fuel efficiency with superior wet-grip performance. In addition, since the new silica dispersant is made from 100% plant-derived ingredients, it contributes to sustainable sourcing of raw materials.
This new technology is already being used in Bridgestone's Ecopia EX20 tire, resulting in a 12% improvement in wet-braking performance without any loss of fuel efficiency.* As the use of this technology gradually spreads to other products, it will contribute further to the development of a sustainable automotive society.