| 摘要 |
PURPOSE:To provide the title carbon black which has a specified particle size range, a specified specific surface area and a specified pH and can reduce volume resistivity by using a small quantity thereof, by thermally decomposing acetylene gas with a gas mixture of oxygen and steam and firing the resulting carbon black in two stages. CONSTITUTION:Acetylene gas or a mixture thereof with an unsaturated hydrocarbon is thermally decomposed with a gas mixture of oxygen and steam. The resulting carbon black is partially oxidized at 500 deg.C or above and then fired at 800 deg.C or above to obtain the desired carbon black for use in the production of semiconductive layers of power cables, whose primary particle has an average particle size of 25nm or below and which has a specific surface area of 500-1,100m<2>/g and a pH of 4-9. Since volume resistivity can be lowered by using a small quantity of said carbon black, power cables obtd. by using said carbon black scarcely cause lowering in the characteristics of resins and have good durability.
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