An ink comprises a coloring material and an aqueous medium wherein the coloring material contains a self-dispersing type carbon black, in which self-dispersing carbon black a hydrophilic group combines with the surface of a carbon black directly or through another atomic group, and which ink contains...http://www.google.es/patents/US6547381?utm_source=gb-gplus-sharePatente US6547381 - Ink, image recording process, ink cartridge, recording unit, ink set, crust-preventing method and image forming apparatus
