Patent ID: 8052786
Filing Date: 2011-11-08
Classification: C09D

Abstract:
1. An inkjet ink set comprising: a first ink having either an acidic pH in the range of about 3 to 6.5 or an alkaline pH in the range of about 7.5 to 10, and comprising a self-dispersed pigment comprising an amphoteric dispersant having an isoelectric point which is between said acidic pH and said alkaline pH, wherein said amphoteric dispersant is chemically bound to the pigment; and a second ink comprising a colorant and having the other of said acidic or alkaline pH, which maintains said colorant in an oppositely charged state relative to said amphoteric dispersant in said first ink, wherein, when said first and second inks are deposited adjacent to each other on a print medium, said adjacent first and second inks interact such that the amphoteric dispersant approaches said isoelectric point whereupon said self-dispersed pigment becomes non-dispersed, thereby forming a boundary between said deposited inks and arresting bleeding of said first ink.