LONDON—There are major technical challenges to overcome before recycled carbon black can be used as an effective alternative filler in tire compounds, according to Bart Kalkstein, president of reinforcement materials at Cabot Corp.
It is important to consider all available opportunities for tire recycling, Kalkstein said out in a Q&A interview. When asked about the potential role of rCB, he said there are significant limitations associated with replacing virgin carbon black with reclaimed pyrolysis carbon.
For starters, he said, the productis not actually a carbon black.
"It is a different carbon material (and) could compromise tire safety and performance if used in more than a small, fractional amount."
Today's technology produces a material that is not homogeneous, Kalkstein said. This is due "to most tires having several different carbon black grades in the various rubber compounds in a tire and many different tire types used in a pyrolysis batch." Moreover, he added, the end-product "contains a variable but significant amount of ash—due to the silica used in tread compounds—and has a surface that is chemically quite different to carbon black.
"While (rCB) can be used today in small loadings as a filler or low-end colorant, it cannot currently serve as a substitute for virgin carbon black as it does not offer the same level of performance," Kalkstein said.
SKalkstein sees a role for reclaimed carbon along with other recycled materials in the future, and Cabot continuing to research this area. But, he concluded, "today there are better uses for this material than as a substitute raw material for rubber grade carbon black."