PURPOSE: To obtain a soft high-structure carbon black having specific physical properties and capable of effectively decreasing the rolling resistance originated from a carcass part when compounded to a rubber composition for tire, especially for carcass part.
CONSTITUTION: This carbon black has the following physical properties. The nitrogen-adsorption specific surface area N2SA is 40-60m2/g, the dibutyl phthalate (DBP) absorption A0 is 160-220 ml/100g, the DBP absorption after compression 24M4DBPA A4 is 98-135 ml/100g, the ratio A1/A0 is 0.82-0.88 (A1 is DBP absorption after one compression treatment), the structure strength index calculated by the formula I (A20 is DBP absorption after 20 compression cycles; Ai is DBP absorption after (i) compression cycles) is 0.25-0.35, the number of pores N on the surface of the carbon black measured by mercury porosimetry is larger than the value calculated by the formula II and the Dst mode diameter which is the most frequent value of the carbon black aggregate diameter determined by centrifugal sedimentation analysis is larger than the value calculated by the formula III.
KOTAKE YASUTO
NIHEI KOICHI
