Major technical challenges with rCB, says Cabot Corp. exec

Recycled carbon black (rCB) is an effective alternative filler in tyre compounds – however, there are significant limitations associated with replacing virgin carbon black with reclaimed pyrolysis carbon. Current technology produces a material that is not homogeneous due to the many different tyre types and different carbon black grades in its various rubber compounds used in a pyrolysis batch.

Bart Kalkstein, President of Reinforcement Materials at Cabot Corporation (Cabot), a leading producer of carbon black, said a different carbon material could compromise tyre safety and performance if used in more than a fractional amount.

He added that the end-product has a surface that is chemically quite different from carbon black and “contains a variable but significant amount of ash — due to the growing use of silica in tread compounds.

Kalkstein explains: “While rCB can be used today in small loadings as a filler or low-end colorant, it cannot currently serve as a substitute for rubber-grade carbon black as it does not offer the same level of performance.”

Despite this, Cabot sees a future role for reclaimed carbon, along with other recycled materials,and will continue to research this area.