Modified pigment containing inkjet ink compositions having a reduced conductivity increase
AssigneeCabot Corporation
InventorsTianqi Liu, Robert J. Nick
Life of this patent
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Abstract
The present invention relates to a modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof, as well as to dispersions and inkjet ink compositions comprising such modified pigments. Preferably the salt comprises a quaternary ammonium counterion.
Claims43
An inkjet ink composition comprising
- a) a liquid vehicle,
- b) an optional cosolvent, and
- c) at least one modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof having a corresponding quaternary ammonium counterion having the structure NR′4+, wherein R′, which can be the same or different, is a C2-C6 alkyl group,
- and wherein the quaternary ammonium counterion has at least 6 total carbons.
An inkjet ink composition comprising
- a) a liquid vehicle,
- b) a cosolvent in an amount of from 10% to 40% by weight based on the total weight of the inkjet ink composition, and
- c) at least one modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof having a corresponding quaternary ammonium counterion having the structure NR′4+, wherein at least one R′, which can be the same or different, is a C2-C6 alkyl group, and wherein the quaternary ammonium counterion has at least 6 total carbons,
- wherein the inkjet ink composition has a conductivity of less than or equal to 1000 microsiemens/cm at a modified pigment content of from 10% to 15% by weight and further has a conductivity of less than or equal to 1000 microsiemens/cm after 4 weeks at 60° C. at a modified pigment content of from 10% to 15% by weight.
A modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof having a corresponding quaternary ammonium counterion having the structure NR′4+, wherein at least one R′, is a C2-C6 alkyl group, and wherein the quaternary alkyl ammonium counterion has at least 6 total carbons.
A method of reducing the conductivity increase of an aqueous modified pigment dispersion comprising the steps of:
- i) providing an aqueous dispersion of a modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof having a corresponding counterion,
- ii) ion exchanging the counterion of the modified pigment to form an aqueous dispersion of a modified pigment comprising a pigment having attached at least one salt of a geminal bisphosphonic acid group or partial esters thereof having a corresponding quaternary ammonium counterion having the structure NR′4+, wherein R′, which can be the same or different, is H, a C1-C6 alkyl group, an aryl group, or form a ring, and wherein the quaternary ammonium counterion has at least 6 total carbons, and
- iii) optionally heat aging the aqueous dispersion of step ii) at a temperature of from 50° C. to 100° C. for a time between 0.5 and 5 days to form an aqueous dispersion of a modified pigment further comprising desorbed ions, and removing the desorbed ions;
- to form the aqueous modified pigment dispersion having a reduced conductivity increase.
Dependencies are inferred from the claim text.