Yokohama Rubber Unveils Nano-Level Steel Cord Rubber Bonding Mechanism for Next-Generation Tires

The Yokohama Rubber Co Ltd announced on June 30 that it has achieved a significant research milestone through a joint study with Japan's Tohoku University Institute of Multidisciplinary Research. The collaborative work clarified the nano-level mechanism responsible for steel cord-rubber bonding and deterioration reduction for the first time in the world. The company considers these findings an important step toward developing next-generation tires with enhanced durability, stronger structural integrity, and improved long-term performance under demanding operating conditions.

Steel cords act as critical reinforcement within tires, making reliable bonding with rubber essential for maintaining strength throughout a tire's service life. To achieve strong initial adhesion while improving long-term resistance to environmental degradation, manufacturers commonly add metal catalysts such as cobalt stearate to the rubber compound. The research team focused on understanding the underlying nano-scale interactions responsible for these performance improvements without altering established tire manufacturing principles.

The researchers directly observed the presence of cobalt sulfide at the bonding interface following the vulcanization process. This observation provides valuable scientific evidence explaining how the bonding mechanism functions at the nano level. The discovery offers deeper insight into material behavior during tire production and establishes a clearer understanding of the interface that connects steel reinforcement with the surrounding rubber compound.

The study further demonstrated that cobalt sulfide enhances both adhesion and degradation resistance by suppressing the leaching of brass-plating components from the steel cord into the rubber. In addition, it helps prevent the formation of voids within the brass itself. Together, these effects contribute to maintaining bond integrity over time, supporting longer-lasting tire performance while reducing deterioration caused by environmental exposure.

Frequently Asked Questions

What did Yokohama Rubber discover about steel cord-rubber bonding?
Yokohama Rubber, working with Tohoku University Institute of Multidisciplinary Research, clarified the nano-level mechanism responsible for steel cord-rubber bonding and deterioration reduction for the first time in the world. The research directly observed cobalt sulfide at the bonding interface after vulcanization and showed that it improves adhesion while reducing degradation by limiting brass-plating component leaching from steel cords and preventing void formation within the brass, supporting the development of more durable next-generation tires.