Patent ID: 8258203

Claim:
An ink set comprising: a first ink and a second ink, wherein said first ink is a black ink-jet ink consisting of a first aqueous vehicle, a polymeric dispersant and a carbon black pigment, wherein said carbon black pigment is stabilized to a carbon black dispersion in said first aqueous vehicle by said polymeric dispersant and wherein said polymeric dispersant is a block copolymer comprising an A block and a B block, wherein said A block consists of 2 to 8 units of methacrylic acid or salt form thereof; said B block comprises at least 2 units of methacrylic acid, or salt form thereof, and at least 16 units of benzylmethacrylate; said block copolymer has a number average molecular weight (Mn) of between about 3,000 and 16,000 Daultons and an acid number of between about 50 and 220; and wherein said second ink comprises a second aqueous vehicle and reactive species that can destabilize the carbon black dispersion of said first ink, and said first ink is underprinted with said second ink and has an optical density of equal to or greater than 1.30, provided that said second ink does not contain a nonionic dispersant.