Abstract: An apparatus for producing carbon black comprises a reaction chamber which consists of a tapered throat and a downstream extension of the throat having the same diameter as that of the narrowest portion of the throat and provided with a plurality of ribs on its inner wall which define a plurality of flits parallel to the axis of the reaction chamber. The reaction chamber is equipped, on the upstream side of the extension, with means for introducing the feedstock oil perpendicularly to the axis of the chamber.

Abstract: A carbon black of the category of hard carbon blacks having a nitrogen adsorption specific surface area (N.sub.2 SA) of 120 to 165 m.sup.2 /g and a DBP absorption number of 120 ml/100 g or more and satisfying requirements respectively represented by the following formulae (1) and (2):Dst.ltoreq.(4.35.times.dn)-10.0 (1) ##EQU1## In the formulae (1) and (2), dn is the arithmetic average diameter (nm) measured by electron microscopy, .DELTA.Dst (nm) is the difference between two Stokes diameters each obtained in a frequency of 50% of the maximum frequency in a distribution curve of the aggregate Stokes diameter, Dst (nm) is the Stokes diameter of the maximum frequency in the distribution curve of the aggregate Stokes diameter, N.sub.2 SA is the nitrogen adsorption specific surface area (m.sup.2 /g) and IA is the iodine adsorption number (mg/g).

Abstract: Carbon black for compounding into a tire tread rubber which has a nitrogen adsorption specific surface area (N.sub.2 SA) of 120 to 165 m.sup.2 /g and a dibutyl phthalate absorption of at least 120 ml/100 g which belong to the respective regions of hard grade of carbon black, and has such a value G defined by the following equation (1) as satisfying the following formula (2): ##EQU1## wherein [.DELTA.D.sub.st ] stands for a difference between two equivalent Stokes diameters at two points on the distribution curve of aggregates at which the absorbance is 50% of the maximum absorbance; [D.sub.st ] stands for an equivalent Stokes diameter (nm) at the maximum absorbance of the distribution curve of aggregates; [N.sub.2 SA] stands for a nitrogen adsorption specific surface area (m.sup.

Abstract: The present invention discloses a carbon black having an N.sub.2 SA of 75 to 105 m.sup.2 /g and a compressive DBP absorption of at least 110 ml/100 g and, at the same time, having the following selective characteristic values:true specific gravity.ltoreq.1.9080-0.0016.times.N.sub.2 SA;void diameter of particle aggregates (nm).gtoreq.62.2-0.236.times.N.sub.2 SA; andrange of aggregate size distribution [.DELTA.Dst (nm)].gtoreq.30.6+0.6118.times.Dst.

Abstract: The present invention discloses carbon black for a tire tread having a cetyltrimethyl ammonium bromide specific surface area (CTAB) of 120 to 160 m.sup.2 /g, a dibutyl phthalate absorption number of compressed sample (24M4) of 95 to 135 ml/100 g, and a tinting strength (Tint) of 100 to 150% and exhibits an M value defined by the following formula (1) and satisfying the following formula (2): ##EQU1## wherein IA is the iodine adsorption number (mg/g), N.sub.2 SA is the nitrogen adsorption specific surface area (m.sup.2 /g), Dst is the equivalent Stokes diameter (nm) at the maximum absorbance of the distribution curve of aggregates determined by the centrifugal classification method, and .DELTA.Dst is the difference (nm) between two equivalent Stokes diameters at two points on the distribution curve of aggregates at which the absorbance is 50% of the maximum absorbance.

Abstract: A rubber composition comprising 35 to 100 parts by weight of a carbon black per 100 parts by weight of a rubber component, the carbon black having a nitrogen adsorption specific surface area (N.sub.2 SA) within a range of 70 to 185 m.sup.2 /g and an aggregate characteristic which shows a first and a second modal diameters in the aggregate equivalent Stokes diameter distribution and has a difference between the two modal diameters L (nm) to be calculated from the following equation (1) which satisfies the following formula (2):L=Dst.sub.2 -Dst.sub.1 (1)20.ltoreq.L.ltoreq.110-0.3 (N.sub.2 SA) (2)wherein Dst.sub.1 and Dst.sub.2 respectively denote the first modal diameter (nm) and the second modal diameter (nm) in the aggregate equivalent Stokes diameter distribution detetermined by a centrifugal classification method.

Abstract: A carbon black for blending in rubber is disclosed, which has a BET specific surface area (N.sub.2 SA) within a range of 65 to 84 m.sup.2 /g, an a value to be obtained according to the following calculation formula, of at least 270 and a ratio of the BET specific surface area (N.sub.2 SA) to the iodine adsorption number (IA), N.sub.2 SA/AI, within a range of 1.10 to 1.35:a=(24M4DBP).sup.2 .times.(Blackness/IA ).sup.2 .times.(Dst).sup.2 .times.10.sup.