Patent ID: 7637603

Claim:
A pigment ink for use in an ink jet recording apparatus in which ejection orifices for a pigment ink and ejection orifices for at least one type of reactive ink that destabilizes a dispersed state of pigment in the pigment ink are capped with an identical cap provided with a unit for removing an ink in the cap, wherein, when a mixed thickening ratio upon mixing the pigment ink and the reactive ink in equal volumes is represented by Y (%) and an ejection orifice-to-ejection orifice distance between the ejection orifice for the pigment ink and the ejection orifice for the reactive ink is represented by X (mm), provided that X>0, then Y and X in the pigment ink and the reactive ink the ejection orifices for which are capped with the identical cap satisfy a relationship represented by the following expression (A): Y ≦ 0.60 X+ 50.0 (A).