Pigment dispersants and pigment compositions containing the same

A pigment dispersant comprising a compound represented by the following formula (I) or (II) or a metal, ammonium or amine salt thereof:

• wherein X1 is a hydrogen atom, a halogen atom, or an alkyl or acylamino group which may be unsubstituted or substituted by at least one atom or group selected from the group consisting of halogen atoms, alkyl groups and an acylamino group, Y1 is an anthraquinonylamino, phenylamino, naphthylamino or phenoxy group which may be unsubstituted or substituted by at least one atom or group selected from the group consisting of halogen atoms, alkyl groups and an acylamino group, R1 is a hydrogen atom or a substituted or unsubstituted alkyl or phenyl group, and R2 is a substituted or unsubstituted alkylene, phenylene or naphthylene group;
• or
• wherein X2 is a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group, R3 is a hydrogen atom or a substituted or unsubstituted alkyl or phenyl group, R4 is a substituted or unsubstituted phenyl or naphthyl group, and n means an average number of sulfonic acid groups introduced in said compound and stands for a number of from 0.5 to 2.