Copper phthalocyanine pigment composition and ink composition containing same

A usual ink composition can be expected to improve ink viscosity to a certain degree, but when used for a glycol ether-based ink recently required, an increase in viscosity in preparing the ink cannot be suppressed. In addition, there is unknown a copper phthalocyanine pigment composition which can satisfy both such an improvement in ink viscosity and resolubility as printability which is important for the glycol ether-based ink. In this situation, a problem to be solved by the present invention is to provide a copper phthalocyanine pigment composition having low viscosity and excellent resolubility in a glycol ether-based ink. It was found that when a copper phthalocyanine pigment is combined with a specified copper phthalocyanine acid derivative, a pigment composition having significantly low viscosity when formed into a glycol ether-based ink, and good familiarity with the ink can be produced, leading to the achievement of the present invention.