Nigrosine dyes and process for preparing same

Abstract

A novel substituted nigrosine dye represented by the formula D-R).sub.n wherein D is a nigrosine dye residue, R is C.sub.3 -C.sub.18 alkyl or alkenyl which may be straight or branched, or aralkyl or aralkenyl which may have a C.sub.1 -C.sub.8 alkyl substituent on the aryl moiety, the R in each case being the same as or different from the others, and n is a number of 1 to 4. The novel nigrosine dye is prepared by reacting a corresponding unsubstituted nigrosine dye with an alkyl halide, alkenyl halide, aralkyl halide, or aralkenyl halide, or with a mixture thereof, to form the substituted nigrosine dye. The novel dye has a high solubility in and compatability with organic solvents and/or resins and is oleophilic and stable and particularly useful for ink compositions and as a charge control agent for the toners of electrophotographic or electrostatic image developers.