Non-aqueous pigment dispersions containing specific dispersion synergists

摘要

A non-aqueous pigment dispersion comprising a colour pigment, a polymeric dispersant, and a dispersion synergist characterized in that the molecular weight of the anionic part of the dispersion synergist containing at least one carboxylate anion is smaller than the molecular weight of the colour pigment and that the anionic part of the dispersion synergist has a similarity coefficient SIM of at least 0.5 with the similarity coefficient defined by: SIM = t . C S + P - C wherein, S represents the number of atoms in the anionic part of the dispersion synergist; P represents the number of atoms in the colour pigment; C represents the largest number of atoms in common between the anionic part of the dispersion synergist and the colour pigment as one continuous structure; and t is an integer representing the number of times that the largest number of atoms in common C fits into the organic colour pigment, without using atoms of the colour pigment twice.