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AssigneeHewlett-Packard Development Company, L.P.
InventorsJohn R Moffatt, Joseph W Tsang
Estimating the term…
A method for dispersing a pigment in an aqueous solution is provided. The method comprises: (a) providing the pigment, which is distinguished in having an azo group and either a β-diketo structure or a hydroxyl group, each conjugatively associated with the azo group; (b) treating a surface of the pigment with a base having sufficient strength (e.g., a pKa of at least 6) to generate a negative charge on the pigment; and (c) reacting the negatively charged pigment with either (1) a first hydrophilic molecule containing at least one functional group comprising a carbon—carbon double bond and a carbonyl that is alpha to the carbon—carbon double bond which reacts via addition to form a hydrophilic group on the pigment or (2) a second hydrophilic molecule containing at least one functional group selected from the group consisting of anionic functional groups, cationic functional groups, and zwitterionic functional groups and at least one suitable leaving group which reacts via substitution to form a hydrophilic group on the pigment. The treated pigment is rendered comparatively soluble in water-based inks, thereby eliminating the need for any dispersant to disperse the pigment.
A method for self-dispersing a pigment in an aqueous solution, said method comprising:
An inkjet ink comprising a vehicle and a colorant, said colorant comprising a base-stabilized pigment, said pigment distinguished in having an azo group and either a β-diketo structure or a hydroxyl group, each conjugatively associated with said azo group, said pigment further including at least one hydrophilic group covalently bonded thereto, comprising either (1) a first hydrophilic group comprising a carbon—carbon double bond and a carbonyl that is alpha to the carbon—carbon double bond attached to said pigment or (2) a second hydrophilic group containing at least one functional group selected from the group consisting of anionic functional groups, cationic functional groups, and zwitterionic functional groups attached to said pigment.
Dependencies are inferred from the claim text.