Patent ID: 6557991
Filing Date: 2003-05-06
Classification: B41J,C09D

Abstract:
An ink jet printing apparatus comprising:a container containing an ink containing an aqueous medium, a first pigment, a second pigment and a polymer dispersant, the first pigment being a self-dispersing pigment having at least one anionic group bound to the surface thereof directly or via another atomic group, the second pigment being a pigment which can be dispersed in the water-based medium with the polymer dispersant, the polymer dispersant comprising at least one of a nonionic polymer and an anionic polymer; a container containing a treating liquid that aggregates at least one of the pigments contained in the ink when the treating liquid and the ink are mixed on the printing medium in a liquid state, the treating liquid containing at least one of a multivalent metal cation and a salt thereof, an ink ejection portion for ejecting the ink; a treating liquid ejection portion for ejecting the treating liquid; and control means for controlling said ink ejection portion and said treating liquid ejection portion so as to eject the ink and the treating liquid, in this order, onto the printing medium so that the ink and the treating liquid are provided onto the printing medium from respective ejection portions and mixed with each other in a liquid state on the printing medium.