Aqueous ionically stabilized dispersions
First Claim
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1. An aqueous pigment dispersion comprising a pigment and a polymeric, ionic dispersant in an aqueous vehicle, wherein:
- (a) the 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 dispersion is less than about 300 nm, and (d) when the aqueous pigment dispersion is added to about 1.5 g of an aqueous salt solution of about 0.20 molar salt, in an amount of (i) one drop for pigment dispersions of about 10 wt% or more solids (based upon the total weight of the dispersion), (ii) two drops for pigment dispersions of about 5-10 wt% solids (based upon the total weight of the dispersion), and (iii) three drops for pigment dispersions of about 5 wt% or less solids (based upon the total weight of the dispersion), the pigment precipitates out of the aqueous salt solution when observed 24 hours after the addition.
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Abstract
Tonically 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. These stabilized dispersions can be utilized to prepare ink jet inks which when printed result in improved optical density and chroma. The stability of the ionically stabilized dispersions are sufficient for ink jet inks.
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25 Claims
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1. An aqueous pigment dispersion comprising a pigment and a polymeric, ionic dispersant in an aqueous vehicle, wherein:
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(a) the 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 dispersion is less than about 300 nm, and (d) when the aqueous pigment dispersion is added to about 1.5 g of an aqueous salt solution of about 0.20 molar salt, in an amount of (i) one drop for pigment dispersions of about 10 wt% or more solids (based upon the total weight of the dispersion), (ii) two drops for pigment dispersions of about 5-10 wt% solids (based upon the total weight of the dispersion), and (iii) three drops for pigment dispersions of about 5 wt% or less solids (based upon the total weight of the dispersion), the pigment precipitates out of the aqueous salt solution when observed 24 hours after the addition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An aqueous pigment dispersion comprising a pigment and a polymeric, ionic dispersant in an aqueous vehicle, wherein:
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(a) the ionic dispersant is physically adsorbed to the pigment, (b) the polymeric ionic dispersant stably disperses the pigment in the aqueous vehicle via ionic stabilization with substantially no steric stabilization, and (c) the average particle size of the dispersion is less than about 300 nm. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification