Aqueous ionically stablized dispersions
First Claim
1. An inkjet ink set comprising a first ink and a second ink, said first ink comprising a pigment, a polymeric ionic dispersant and an aqueous vehicle, wherein:
- (a) the polymeric ionic dispersant is physically adsorbed to the pigment, (b) the polymeric ionic dispersant stably disperses the pigment in the aqueous vehicle, (c) the average particle size of the dispersed pigment is less than about 300 nm, (d) when three drops of the first ink is added to about 1.5 g of an aqueous salt solution of about 0.20 molar salt, the pigment precipitates out of the aqueous salt solution when observed 24 hours after the addition; and
, said second aqueous ink comprising a fixing agent capable of fixing the pigment in the first aqueous inkjet ink.
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Abstract
Ironically stabilized dispersions are described that are substantially free of steric stabilization of the pigment. These ionically stabilized dispersions are obtained from polymeric dispersants where the hydrophilic components are minimized. The dispersions can be utilized to prepare ink jet inks which when printed provide advantageous optical density and chroma. Inkjet inks comprising ionically stabilized dispersion are particularly well suited for use in combination with a fixer and the present invention is directed to an inks set with such a combination of inks and to a printing method using this ink set.
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Citations
12 Claims
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1. An inkjet ink set comprising a first ink and a second ink, said first ink comprising a pigment, a polymeric ionic dispersant and an aqueous vehicle, wherein:
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(a) the polymeric ionic dispersant is physically adsorbed to the pigment, (b) the polymeric ionic dispersant stably disperses the pigment in the aqueous vehicle, (c) the average particle size of the dispersed pigment is less than about 300 nm, (d) when three drops of the first ink is added to about 1.5 g of an aqueous salt solution of about 0.20 molar salt, the pigment precipitates out of the aqueous salt solution when observed 24 hours after the addition; and
,said second aqueous ink comprising a fixing agent capable of fixing the pigment in the first aqueous inkjet ink. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification