Carbon blacks modified with organosilicon compounds, method of their production and their use in rubber mixtures

Carbon blacks which are chemically modified with at least one organosilicon compound selected from the group consisting of

• [R.sup.1.sub.n (RO).sub.3-n Si-(Alk).sub.m -(Ar).sub.p ]q [B](I)
• R.sup.1.sub.n (RO).sub.3-n Si-(Alkyl) (II)
• R.sup.1.sub.n (RO).sub.3-n Si-(Alkenyl) (III)
• in which
• B represents --SCN, --SH, --Cl, --NH.sub.2 (if q=1) or --Sx--(if q=2),
• R and R.sup.1, which may be the same or different, represent an alkyl group containing 1 to 4 carbon atoms or the phenyl group,
• q represents 1 or 2,
• n represents 0, 1 or 2,
• Alk represents a bivalent straight or branched hydrocarbon group containing 1 to 6 carbon atoms,
• m represents 0 or 1,
• Ar represents an arylene group containing 6 to 12 carbon atoms,
• p represents 0 or 1 provided that p and n do not simultaneously signify 0,
• x represents a number from 2 to 8,
• Alkyl represents a monovalent straight or branched unsaturated hydrocarbon group containing 1 to 20 carbon atoms,
• alkenyl represents a monovalent straight or branched unsaturated hydrocarbon group containing 2 to 20 carbon atoms,
• and on the surface of which blacks 0.1 to 15 % by weight of one or more of the named organosilicon compounds are bonded in such a manner that they can not be extracted with organic solvents.