Ink-jet ink comprising cross-linked pigment dispersion and a polymeric binder

1. An ink-jet ink comprising an aqueous ink vehicle, an aqueous pigment dispersion and a polymeric binder, wherein said aqueous pigment dispersion is prepared by dispersing a colorant with a polyurethane dispersant followed by cross-linking of said polyurethane dispersant, and said polymeric binder is non-reactive to said colorant, and wherein said polyurethane dispersant is comprised of a polymer with:

(a) an aqueous dispersing moiety, and

(b) a cross-linkable moiety that is cross-linked with a cross-linking agent after said polyurethane dispersant disperses said colorant to form said pigment dispersion, wherein said cross-linkable moiety is pendent to the polymer backbone and terminal to the polymer chain;

wherein the polyurethane dispersant prior to being cross-linked comprises at least one compound of the general structure of Formula I:

wherein each X is independently OH, SH, COOH or NHR 4 ;

each Y is independently O, S or NR 4 ;

each W is NH, O or S;

each R 1 is independently C 1 -C 20 alkylene, or C 6 -C 40 arylene;

R 2 is comprised of difunctional isocyanate reactants Z 1 , Z 2 and Z 3 , wherein there is at least one Z 1 , at least one Z 2 and at least one Z 3 ;

each R 3 is independently C 1 -C 20 alkylene;

each R 4 is independently —R 3 -A, H or C 1 -C 20 alkylene;

each A is OH, SH or COOH;

n is an integer from 2 to 30;

Z 1 is a difunctional isocyanate reactant substituted with an aqueous dispersing moiety;

Z 2 is a difunctional isocyanate reactant substituted with one or more cross-linkable moieties; and

Z 3 is a polyol with a weight average molecular weight of less than 3000.

2. The ink of claim 1 , wherein the polymeric binder is one or more members selected from the group consisting of polyurethane, acrylics, styrene acrylics, styrene butadienes, styrene butadiene acrylonitriles, neoprenes, ethylene acrylic acid copolymer, ethylene vinyl acetate, and mixtures thereof.

3. The ink of claim 2 , wherein the cross-linking agent is one or more members selected from the group consisting of epoxide, isocyanate, carbodiimide, N-methylol, oxazoline, silane, and mixtures thereof.

4. The ink of claim 3 , wherein Z 1 is a polyol substituted with the aqueous dispersing moiety.

5. The ink of claim 4 , wherein Z 2 is a polyol substituted with one or more cross-linkable moieties.

6. The ink of claim 5 , wherein the aqueous dispersing moiety consists of one or more carboxyl groups.

7. The ink of claim 6 , wherein the cross-linkable moiety consists of one or more carboxyl groups.

8. The ink of claim 7 , wherein Y is NR 4 .

9. The ink of claim 8 , wherein the polymeric binder is polyurethane.

10. The ink of claim 3 , wherein X is OH.

11. The ink of claim 10 , wherein Z 1 is a polyol substituted with the aqueous dispersing moiety.

12. The ink of claim 11 , wherein Z 2 is a polyol substituted with one or more cross-linkable moieties.

13. The ink of claim 12 , wherein the polymeric binder is polyurethane.

14. The ink of claim 3 , wherein X is NHR 4 .

15. The ink of claim 14 , wherein Z 1 is a polyol substituted with the aqueous dispersing moiety.

16. The ink of claim 15 , wherein Z 2 is a polyol substituted with one or more cross-linkable moieties.

17. The ink of claim 3 , wherein R 4 is —R 3 -A and the polymeric binder is polyurethane.

18. The ink of claim 17 , wherein each W is O.

19. The ink of claim 17 , wherein each W is NH.

20. The ink of claim 3 , wherein the mole ratio of the cross-linkable moiety to the cross-linking agent is from 15:1 to 1:1.5.