Process for preparing colored pigments

Abstract

The present invention relates to a process for preparing surface-modified colored pigments. The process includes the steps of: preparing a reaction batch comprising a treating agent and a diazotizing agent; adding a colored pigment to the batch; and mixing the colored pigment and the batch under high shear conditions to form a reaction product comprising a surface-modified colored pigment. The treating agent has an organic group which comprises at least one diazotizable group. In a preferred embodiment the diazotizable group comprises a) at least one aromatic group or at least one C1-C20 alkyl group, and b) at least one ionic group, ionizable group, nonionic group, or a mixture thereof. The surface-modified colored pigments prepared by the process of the present invention have been found useful in aqueous or solvent based compositions and particularly in ink jet ink compositions.

Dependencies are inferred from the claim text.