Race Tires Adopt Recycled Carbon

Event Focus: Recycled Carbon Black Debuts in Racing Tires

Sumitomo Rubber will be in the spotlight at the fourth round of the 2025 Autobacs Super GT, taking place in Shizuoka Prefecture, Japan, from August 2nd to 3rd. The company will introduce recycled carbon black (rCB) in some of its racing tires for the first time.

This innovative move, the result of a close collaboration between Sumitomo Rubber and Mitsubishi Chemical since January of this year, promises a new dawn of change in the tire material industry.

R&D Core: Transforming Waste into Recycled Carbon Black

Since the beginning of 2025, Sumitomo Rubber and Mitsubishi Chemical Corporation have been committed to the research and development of sustainable carbon black. Focusing on rubber waste and used tires generated during tire manufacturing, they have successfully obtained recycled carbon black through advanced chemical recycling methods and pyrolysis technology.

This groundbreaking material is not simply a substitute, but rather a partial replacement for traditional virgin materials in tire compounds, opening up new resource utilization opportunities for the tire manufacturing industry.

Technical Challenges: Overcoming Impurity Removal

The collaborative team faced numerous challenges throughout the R&D process. Scrap tires are complex, containing impurities such as steel wire, fiber, and various additives. Efficiently removing these impurities was a primary challenge in obtaining high-quality recycled carbon black.

After repeated experiments, experts from Sumitomo Rubber and Mitsubishi Chemical employed a series of advanced raw material pretreatment technologies, including magnetic separation and air separation, to significantly reduce impurities in scrap tires, reducing the ash content from approximately 15% to below 5%, significantly improving the purity of the recycled carbon black.

Process Optimization: Low-Temperature Pyrolysis Improves Carbon Black Quality

Optimizing the pyrolysis process is also crucial. Traditional thermal pyrolysis typically operates at temperatures around 600°C. Such high temperatures not only consume significant energy but also easily lead to coking, compromising carbon black quality.

To address this, the collaborative team boldly experimented with low-temperature catalytic pyrolysis technology, similar to the continuous thermal pyrolysis process used by Germany's Pyrum, cleverly lowering the pyrolysis temperature to 450°C. This adjustment has had a significant impact, not only reducing coking problems but also significantly increasing the surface activity of carbon black, with its DBP absorption reaching 120-130 mL/100 g, laying a solid foundation for its future application in tires.

Application Promotion: Expanding from Racing to Passenger Cars

From a perspective of application prospects, the introduction of recycled carbon black in racing tires is just the beginning. Sumitomo Rubber plans to further expand this innovation to selected passenger car tires by 2025. This initiative is expected to not only reduce tire production's reliance on virgin materials but also play a positive role in reducing CO2 emissions.

According to Sumitomo Rubber, this system enables the resource recycling of rubber waste and used tires, previously burned solely as a heat source, and is expected to effectively reduce CO2 emissions and contribute to the achievement of global sustainable development goals.

Performance Potential: Adapting to Diverse Tire Needs

Recycled carbon black also demonstrates significant potential in high-performance tire formulations. For example, in ATV tire tread compound, when 20 parts of high-quality recycled carbon black replaces 15 parts of conventional carbon black N330, the compound's processing, vulcanization, and mechanical properties are comparable to the original formula, while also reducing rolling resistance and heat generation.

New energy vehicle tires have specific requirements for low rolling resistance and high wear resistance. The development of a composite reinforcement system of recycled carbon black and silica can improve wet grip and increase range, perfectly aligning with the development trend of new energy vehicles.

Industry Impact: Setting a Benchmark for Sustainable Development

The collaboration between Sumitomo Rubber and Mitsubishi Chemical in the field of recycled carbon black has set a new benchmark for sustainable development in the tire industry, leading the industry towards green and circular development. The future is promising.