Aqueous inkjet ink sets and inkjet printing methods

1. A pigmented aqueous inkjet ink set for manufacturing decorative panels, the pigmented aqueous inkjet ink set consisting of:

a red aqueous inkjet ink including at least about 2.0 wt % of a red pigment selected from the group consisting of C.I. Pigment Red 254, C.I. Pigment Red 176, and mixed crystals thereof;

a yellow aqueous inkjet ink including at least about 2.0 wt % of C.I Pigment Yellow 150 or a mixed crystal thereof;

a black aqueous inkjet ink including at least about 2.0 wt % of a carbon black pigment; and

optionally, a cyan aqueous inkjet ink including at least about 2.0 wt % of a copper phthalocyanine pigment;

wherein each of the aqueous inkjet inks includes less than about 1 wt %, based on the total weight of the aqueous ink, of a surfactant;

wherein the viscosity of the aqueous inkjet inks at a temperature of about 32° C. is between about 5 and about 12 mPa/s at a shear rate of 1,000 s −1 ; and

wherein the static surface tension of the aqueous inject inks at a temperature of about 25° C. is between about 19.0 mN/m and 27.0 mN/m.

2. The pigmented aqueous inkjet ink set as claimed in claim 1 , wherein the surfactant is a fluoro surfactant.

3. The pigmented aqueous inkjet ink set as claimed in claim 1 , wherein the red pigment is C.I. Pigment Red 254 or a mixed crystal thereof.

4. The pigmented aqueous inkjet ink set as claimed in claim 1 , wherein a hue angle H* of the yellow aqueous inkjet ink is higher than 85°.

5. An inkjet printing method for manufacturing decorative panels comprising:

providing a paper substrate including at least one ink receiving layer;

jetting a color image with the pigmented aqueous inkjet ink set as claimed in claim 1 on the at least one ink receiving layer of the paper substrate; and

drying the color image that has been jetted onto the at least one ink receiving layer;

wherein the pigmented aqueous inkjet ink set is jetted at a temperature between about 25° C. and about 35° C.; and

wherein the at least one ink receiving layer is coated on the paper substrate by a coating technique selected from the group consisting of dip coating, knife coating, extrusion coating, spin coating, slide hopper coating, curtain coating, and combinations thereof.

6. The inkjet printing method as claimed in claim 5 , wherein the step of jetting the color image is performed in a multi-pass mode.

7. The inkjet printing method as claimed in claim 5 , wherein the color image includes a wood motif including wood nerves extending in a direction substantially corresponding to an inkjet printing direction.

8. The inkjet printing method as claimed in claim 5 , wherein the at least one ink receiving layer includes a plurality of ink receiving layers; and

an outermost ink receiving layer contains no inorganic pigment or an amount of inorganic pigment less than that of any ink receiving layer located between the paper substrate and the outermost ink receiving layer.

9. The inkjet printing method as claimed in claim 5 , wherein the at least one ink receiving layer includes an inorganic pigment selected from the group consisting of alumina hydrates, aluminum oxides, aluminum hydroxides, aluminum silicates, and silicas.

10. The inkjet printing method as claimed in claim 5 , wherein the at least one ink receiving layer includes a polymeric binder selected from the group consisting of polyvinylalcohol, a vinylalcohol copolymer, or modified polyvinyl alcohol.

11. A method for manufacturing decorative panels comprising the inkjet printing method as claimed in claim 5 ; wherein

after the steps of jetting and drying the color image, impregnating the paper substrate with a thermosetting resin.

12. The method for manufacturing decorative panels as claimed in claim 11 , further comprising:

heat pressing the impregnated paper substrate between a core layer and a protective layer; and

cutting the heat pressed impregnated paper substrate into a decorative panel selected from the group consisting of flooring, kitchen, furniture, and wall panels.

13. The method for manufacturing decorative panels as claimed in claim 12 , wherein the decorative panel includes a tongue and groove mechanical joint that requires no glue.

14. The pigmented aqueous inkjet ink set as claimed in claim 1 , comprising the cyan aqueous inkjet ink.