Ink set for inkjet printers

1. An ink set for an inkjet printer, comprising:

at least one first ink comprising:

at least one pigment for providing a first color of the first ink;

a first media comprising water;

at least one first non-ionic surfactant having a first HLB (Hydrophilic Lipophilic Balance) value;

at least one second ink comprising:

at least one second colorant for providing a second color of the second ink;

a second media comprising water; and

at least one second non-ionic surfactant having a second HLB value, wherein the first HLB value is smaller than or equal to the second HLB value.

2. The ink set of claim 1 , wherein the concentration of the at least one pigment ranges from 1 wt % to 15 wt %.

3. The ink set of claim 1 , wherein the average particle size of the at least one pigment is less than 1 μm.

4. The ink set of claim 1 , wherein the first media comprises at least one additive selected from the group consisting of an organic solvent, a humectant, a buffer and a biocide.

5. The ink set of claim 1 , wherein the concentration of the water in the first ink ranges from 50 wt % to 95 wt %.

6. The ink set of claim 1 , wherein the concentration of the first non-ionic surfactant ranges from 0.001 wt % to 10 wt %.

7. The ink set of claim 6 , wherein the concentration of the first non-ionic surfactant ranges from 0.001 wt % to 3.5 wt %.

8. The ink set of claim 1 , wherein the second colorant comprises a dye.

9. The ink set of claim 8 , wherein the concentration of the second colorant ranges from 0.5 wt % to 14 wt %.

10. The ink set of claim 1 , wherein the second media comprises at least one additive selected from the group consisting of an organic solvent, a humectant, a buffer and a biocide.

11. The ink set of claim 1 , wherein the concentration of the water in the second ink ranges from 50 wt % to 95 wt %.

12. The ink set of claim 1 , wherein the concentration of the second non-ionic surfactant ranges from 0.001 wt % to 10 wt %.

13. The ink set of claim 12 , wherein the concentration of the second non-ionic surfactant ranges from 0.001 wt % to 3.5 wt %.

14. The ink set of claim 1 , wherein the lightness of the first ink is lower than the lightness of the second ink.

15. The ink set of claim 1 , wherein the first color is black and the second color comprises at least one of cyan, magenta and yellow.

16. A printing method for reducing ink bleeding, comprising:

(a) providing an ink set in an inkjet printer, wherein the ink set comprises:

at least one first ink comprising:

at least one pigment for providing a first color of the first ink;

a first media comprising water;

at least one first non-ionic surfactant having a first HLB (Hydrophilic Lipophilic Balance) value;

at least one second ink comprising:

at least one second colorant for providing a second color of the second ink;

a second media comprising water; and

at least one second non-ionic surfactant having a second HLB value;

wherein the first HLB value is smaller than or equal to the second HLB value; and

(b) ejecting the ink set on a recording medium.

17. The method of claim 16 , wherein the concentration of the at least one pigment ranges from 1 wt % to 15 wt %.

18. The method of claim 16 , wherein the concentration of the first non-ionic surfactant ranges from 0.001 wt % to 10 wt %.

19. The method of claim 18 , wherein the concentration of the first non-ionic surfactant ranges from 0.001 wt % to 3.5 wt %.

20. The method of claim 16 , wherein the second colorant comprises a dye.

21. The method of claim 20 , wherein the concentration of the second colorant ranges from 0.5 wt % to 14 wt %.

22. The method of claim 16 , wherein the concentration of the second non-ionic surfactant ranges from 0.001 wt % to 10 wt %.

23. The method of claim 22 , wherein the concentration of the second non-ionic surfactant ranges from 0.001 wt % to 3.5 wt %.

24. The method of claim 16 , wherein the lightness of the first ink is smaller than the lightness of the second ink.

25. The method of claim 16 , wherein the first color is black and the second color comprises at least one of cyan, magenta and yellow.

26. An ink set for an inkjet printer, comprising:

at least one first ink comprising:

at least one first colorant for providing a black color of the first ink;

a first media comprising water; and

at least one first non-ionic surfactant having a first HLB (Hydrophilic Lipophilic Balance) value;

at least one second ink comprising:

at least one second colorant for providing a non-black color of the second ink;

a second media comprising water; and

at least one second non-ionic surfactant having a second HLB value,

wherein the first HLB value is no greater than the second HLB value.

27. The ink set of claim 26 , wherein the first colorant comprises pigment.

28. The ink set of claim 26 , wherein the first colorant comprises dye.

29. A printing method of reducing ink bleeding, comprising:

(a) providing an ink set in an inkjet printer, wherein the ink set comprises:

at least one first ink comprising:

at least one first colorant for providing a black color of the first ink;

a first media, comprising water;

at least one first non-ionic surfactant having a first HLB (Hydrophilic Lipophilic Balance) value;

at least one second ink comprising:

at least one second colorant for providing a non-black color of the second ink;

a second media comprising water; and

at least one second non-ionic surfactant having a second HLB value;

wherein the first HLB value is no greater than the second HLB value; and

(b) ejecting the ink set on a recording medium.

30. The method of claim 29 , wherein the first colorant comprises pigment.

31. The method of claim 29 , wherein the first colorant comprises dye.