Wetting enhancement coating on intermediate transfer member (ITM) for aqueous inkjet intermediate transfer architecture

1. A method for transfix ink jet printing comprising:

coating a wetting enhancement coating on a transfer member, wherein the wetting enhancement coating comprises; water, a cationic starch, a humectant and a surfactant;

drying the wetting enhancement coating to form a film having a thickness of from about 0.05 microns to about 5 microns;

ejecting ink droplets to form an inkjet image on the film; and

transferring the inkjet image and the film onto a recording medium.

2. The method of claim 1 , wherein the cationic starch comprises more than 90 weight percent amylopectin having a positive charged moiety substituted for a hydroxyl group in the amylopectin.

3. The method of claim 2 , wherein the amylopectin is represented by:

wherein there is 1 α-1,6 linkage for every 12 to 30 α-1,4 linkages for a unit (C 6 H 12 O 6 ) m and where m equals 12 to 30.

4. The method of claim 2 , wherein the amylopectin having a positive charged moiety substituted is represented by:

wherein R 1 , R 2 and R 3 are hydrogen, alkyl, aryl and alkylaryl.

5. The method of claim 4 , wherein the nitrogen level in the positive charged moiety substituted cationic starch is from about 0.1 percent to about 0.6 percent.

6. The method of claim 1 , wherein a weight percent of the cationic starch in the wetting enhancement coating is from about 1 weight percent to about 10 weight percent.

7. The method of claim 1 , wherein the humectant in wetting enhancement coating is selected from the group consisting of glycerol, sorbitol, glycols and mixtures thereof.

8. The method of claim 1 , wherein a weight percent of the humectant in the wetting enhancement coating is from about 1 weight percent to about 8 weight percent.

9. The method of claim 1 , wherein a weight percent of the wetting enhancement coating further comprises a biocide in an amount of from about 0.1 weight percent to about 2 weight percent.

10. The method of claim 1 , wherein the transfer member has surface free energy from 16 to 30 mN/m.

11. The method of claim 1 , wherein the surfactant is selected from the group consisting of anionic surfactants, non-ionic surfactants and cationic surfactants from about 0.1 weight percent to about 2.0 weight percent of the wetting enhancement coating.

12. The method of claim 1 , wherein the viscosity of cationic starch is less than 500 cps at 10 percent solid weight percent at room temperature.

13. The method of claim 1 , wherein a weight ratio of humectant to cationic starch in wetting enhancement coating is from 1:1 to 5:1.

14. An ink jet printer comprising: a transfer member; a wetting enhancement coating station adjacent said transfer member that provides a wetting enhancement coating on the transfer member wherein the wetting enhancement coating comprises; water, a cationic starch, a humectant and a surfactant; a drying station adjacent said transfer member for drying the wetting enhancement coating to form a film on the transfer member; a print head adjacent said transfer member that ejects aqueous ink droplets onto the film; a transfixing station located adjacent said transfer member and downstream from said print head, the transfixing station having a transfixing roll forming a transfixing nip therewith at said transfixing station; a transporting device for delivering a recording medium to the transfixing nip wherein the ink image and film are transferred to the recording medium.

15. The inkjet printer of claim 14 , wherein the cationic starch comprises more than 90 weight percent amylopectin having a positive charged moiety substituted for a hydroxyl group in the amylopectin.

16. The inkjet printer of claim 14 , wherein the amylopectin is represented by:

wherein there is 1 α-1,6 linkage for every 12 to 30 α-1,4 linkages for a unit (C 6 H 12 O 6 ) m and where m equals 12 to 30.

17. The inkjet printer of claim 16 , wherein the amylopectin having a positive charged moiety substituted is represented by:

wherein R 1 , R 2 and R 3 are hydrogen, alkyl, aryl and alkylaryl.

18. The inkjet printer of claim 17 , wherein the nitrogen level in the positive charged moiety substituted cationic starch is from about 0.1 percent to about 0.6 percent.

19. The inkjet printer of claim 14 , wherein the amylopectin having a positive charged moiety substituted is represented by:

20. An ink jet printer comprising: a transfer member; a wetting enhancement coating station adjacent said transfer member that provides a wetting enhancement coating on the transfer member wherein the wetting enhancement coating comprises; water, a cationic starch, a humectant and a surfactant wherein the cationic starch comprises more than 90 weight percent amylopectin having a positive charged moiety substituted for a hydroxyl group in the amylopectin; a drying station adjacent said transfer member for drying the wetting enhancement coating to form a film on the transfer member; a print head adjacent said transfer member that ejects aqueous ink droplets onto the film; a transfixing station located adjacent said transfer member and downstream from said print head, the transfixing station having a transfixing roll forming a transfixing nip therewith at said transfixing station; a transporting device for delivering a recording medium to the transfixing nip wherein the ink image and film are transferred to the recording medium.