| 摘要 |
The pH of furnace black is reduced from above 7 to a value between 2.9 and 7 by intimately contacting with a current of oxygen-containing gas at a temperature below 1,200 DEG F. The treatment also results in an increased hardness of pellets made from the black and in an increased scorch time of rubber compositions containing the black (see Group V). Treatment may be effected with a gas containing 2.5 to 10 per cent by volume of oxygen, preferably at a temperature of 650-1000 DEG F. or with ozonised air at 80-100 DEG F. Used gas may be mixed with the required amount of air and recycled. Pelleting of the black in a tumbling drum may be carried out before, during, or after the oxidising treatment. |
