Inkjet inks with improved bleed performance

• US 20070252880A1
• Filed: 04/27/2006
• Published: 11/01/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Vasudevan, Sundar
• Granted Patent: US 7,479,180 B2
• Time in Patent Office: Days
• US Class Current: 347/100
• CPC Class Codes: C09D 11/40 Ink-sets specially adapted for multi-colour inkjet printing

Abstract

Inkjet ink formulations, and ink sets and methods using the same, with improved performance, wherein the inks are formulated to work as an ink set having different polarities.

Claims

1. An inkjet ink set, comprising:

a. A plurality of inks including at least a first and a second ink, each ink comprising an aqueous vehicle;

b. a first pigmented colorant dispersed in the first ink and having a pre-determined first polarity; and

c. a second pigmented colorant being different than the first colorant and dispersed in the second ink and having a pre-determined second polarity opposite that of the first polarity of the first ink;

wherein at least one of the colorants of either the first or the second ink is substantially achromatic and the other is substantially chromatic.

2. An ink set according to claim 1 wherein, the second ink initially has an initial polarity similar to that of the first ink and the second polarity is achieved by the addition of a surfactant to the second ink in sufficient amount to reverse the second ink'"'"'s initial polarity from the initial polarity to the second polarity.

3. An ink set according to claim 1 wherein, the second ink has a first zeta potential at the initial polarity and a second zeta potential opposite that of the first zeta potential.

4. An ink set according to claim 3 wherein, the first zeta potential goes through a zero point before reversing its path to the second zeta potential in a direction opposite that of the first polarity.

5. An ink set according to claim 1 wherein, the first ink includes a substantially achromatic pigment.

6. An ink set according to claim 1 wherein, the second ink includes a substantially chromatic color pigment.

7. An ink set according to claim 1 wherein, the first ink includes a substantially chromatic color pigment.

8. An ink set according to claim 1 wherein, the second ink includes a substantially achromatic pigment.

9. An ink set according to claim 1 wherein, at least one of the pigmented colorants is a self dispersing pigment.

10. An ink set according to claim 1 wherein, the pigmented colorants in both inks independently are associated with counterions selected from the group consisting of Na⁺, Li⁺, K⁺, and NH₄⁺.

11. An ink set according to claim 1 wherein, the pigmented colorants in both inks are independently associated with counterions selected from the group consisting of acetate, formate, chloride, gluconate, succinate, tartrate, glutarate, malonate, carboxylate, fumarate, malate, sebacate, adipate, stearate, oleate, laurate, benzoate, and citrate.

12. An ink set according to claim 1 wherein, the ink including a substantially chromatic color pigment is one of cyan, magenta, or yellow.

13. An ink set according to claim 2 wherein, the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.01 to about 5.0%;

by weight, based on the total weight of the ink.

14. An ink set according to claim 2 wherein, the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.2 to about 2.0;

by weight, based on the total weight of the ink.

15. An ink set according to claim 2 wherein, the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.4 to about 1.5%;

by weight, based on the total weight of the ink.

16. An ink set according to claim 10 wherein, the ink further comprises a secondary surfactant which will not interfere with the primary surfactant and is added in an amount ranging from about 0.01 to about 2.5%;

by weight, based on the total weight of the ink.

17. A method for enhancing bleed performance using an inkjet printer, comprising:

a. ejecting at least one drop of a first inkjet ink comprising a first pigmented colorant dispersed in the first ink and having a pre-determined first polarity, and;

b. ejecting at least one drop of a second inkjet ink comprising a second pigmented colorant being different than the first colorant and dispersed in the second ink and having a pre-determined second polarity opposite that of the first polarity of the first ink;

wherein at least one of the colorants of either the first or the second ink is substantially achromatic and the other is substantially chromatic.

18. A method according to claim 17 wherein, the second ink initially has an initial polarity similar to that of the first ink and the second polarity is achieved by the addition of a surfactant to the second ink in sufficient amount to reverse the second ink'"'"'s initial polarity from the initial polarity to the second polarity.

19. A method according to claim 17 wherein, the second ink has a first zeta potential at the initial polarity and a second zeta potential opposite that of the first zeta potential.

20. A method according to claim 19 wherein, the first zeta potential goes through a zero point before reversing its path to the second zeta potential in a direction opposite that of the first polarity.

21. A method according to claim 18 wherein the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.01 to about 5.0%;

by weight, based on the total weight of the ink.

22. A method according to claim 18 wherein, the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.2 to about 2.0;

by weight, based on the total weight of the ink.

23. A method according to claim 18 wherein, the surfactant added to the second ink to reverse the polarity from a first to a second polarity is a primary surfactant added in an amount ranging from about 0.4 to about 1.5%;

by weight, based on the total weight of the ink.