Process for preparing self-dispersible coloring agent using lewis acids and ink composition comprising the coloring agent

Abstract

A self-dispersible coloring agent represented by formula (II) below is prepared by incorporating a hydrophilic group into a coloring agent through a reaction of a hydrophilic group-containing halide represented by formula (I) below and the coloring agent in the presence of a Lewis acid catalyst:X-L-R  (I)(the coloring agent)-L-R  (II) wherein L represents a single bond or —C(═O)—; Ris selected from the group consisting of a substituted or unsubstituted C-Calkyl group containing a hydrophilic group, a substituted or unsubstituted C-Caryl group containing a hydrophilic group a substituted or unsubstituted C-Cheteroaryl group containing a hydrophilic group and a substituted or unsubstituted C-Carylalkyl group containing a hydrophilic group; and X is one of: —F, —Br, —I and —Cl. may be obtained conveniently through a one-step process. The ink composition containing the self-dispersible coloring agent provides effective long-term storage stability and dispersion stability using a one-step process.