Print speed, print quality, bleed, and waterfastness with cationic black pigments and underprinting with anionic dyes

• US 6,386,695 B1
• Filed: 09/11/2000
• Issued: 05/14/2002
• Est. Priority Date: 09/11/2000
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Kowalski, Mark H.
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Shah, Manish S.
• Application Number:
  US09/660,551
• Time in Patent Office: 610 Days
• Field of Search: 347/100, 347/101, 347/96
• US Class Current: 347/100
• CPC Class Codes: B41J 2/2107 characterised by the ink properties supplying ink in a solid state B41J2/17593
• CPC Class Codes: B41M 5/0017 Application of ink-fixing material, e.g. mordant, precipitating agent, on the substrate prior to printing, e.g. by ink-jet printing, coating or spraying
• CPC Class Codes: B41M 5/0023 Digital printing methods characterised by the inks used inks per se C09D11/00
• CPC Class Codes: B41M 7/0018 using ink-fixing material, e.g. mordant, precipitating agent, after printing, e.g. by ink-jet printing, coating or spraying
• CPC Class Codes: C09D 11/40 Ink-sets specially adapted for multi-colour inkjet printing

Abstract

A method of printing an ink onto a print medium is provided. In the method, two inks are employed, a first ink that includes at least one water-soluble color dye that has a first charge, e.g., anionic, and a second ink that includes at least one black pigment that has a second and opposite charge, e.g., cationic. The method comprises: (a) providing the first ink, which contains at least one water-soluble, anionic color dye and at least one surfactant; (b) providing the second ink, which contains at least one cationic black pigment; (c) printing in a first pass across the print medium the first ink; (d) printing the second ink over the first ink, totally covering and overlapping the first ink, whereby the cationic black pigment(s) reacts with the anionic color dye(s) to form an insoluble complex on the print medium, and the surfactant draws the vehicle into the print medium, thereby improving print speed, print quality, bleed, and waterfastness of the ink. A printed ink set is also provided. The printed ink set comprises the cationic black pigment-based ink printed over the anionic color dye-based ink.

Claims

1. A method of printing a black ink onto a print medium, said black ink containing at least one black pigment, said method comprising:

(a) providing a color ink containing at least one water-soluble color dye having a first charge and at least one surfactant;

(b) providing said black ink, said at least one black pigment having a second and opposite charge;

(c) printing in a first pass across said print medium said color ink; and

(d) printing said black ink over said color ink, totally covering and overlapping said color ink such that said black ink is underprinted by said color ink, whereby said at least one black pigment reacts with said at least one color dye to form an insoluble complex on said print medium due to the presence of the opposite charges, thereby improving print speed, print quality, bleed, and waterfastness of said black ink.

2. The method of claim 1 wherein said color dye is selected from the group consisting of cyan, yellow, and magenta.

3. The method of claim 2 wherein cyan ink is printed in one pass in a first direction prior to printing said black ink thereon and magenta ink is printed in an opposite pass in a second direction prior to printing said black ink thereon.

4. The method of claim 1 wherein said surfactant is present in said color ink in a concentration ranging from about 0.2 to 5 wt %.

5. The method of claim 4 wherein said concentration is about 2 wt %.

6. The method of claim 4 wherein said color ink has a surface tension within a range of about 15 dynes/cm up to that of said black ink.

7. The method of claim 1 wherein said black ink has a surface tension of at least that of said color ink.

8. The method of claim 1 wherein said color ink is printed in said first pass and said black ink is subsequently printed in said first pass, in either direction.

9. The method of claim 1 wherein said color ink is printed in said first pass and said black ink is subsequently printed in a second pass.

10. The method of claim 1 wherein said at least one water-soluble color dye in said color ink is anionic and wherein said at least one black pigment in said black ink is cationic.

11. The method of claim 1 wherein one volume of said color ink is printed in an area in said first pass and wherein from five to nine volumes of said black ink are printed over said area.

12. The method of claim 11 wherein six volumes of said black ink are printed over said area.

13. A method of improving print speed, print quality, bleed, and waterfastness of a black ink containing at least one black pigment, said method comprising:

(a) providing a color ink containing at least one water-soluble color dye having a first charge and at least one surfactant;

(b) providing said black ink, said at least one black pigment having a second and opposite charge;

(c) printing in a first pass across said print medium said color ink; and

(d) printing said black ink over said color ink, totally covering and overlapping said color ink such that for every one volume of said color ink printed in an area, from five to nine volumes of said black ink are printed in said area,

whereby said at least one black pigment reacts with said at least one color dye to form an insoluble complex on said print medium due to the presence of the opposite charges.

14. The method of claim 13 wherein said color dye is selected from the group consisting of cyan, yellow, and magenta.

15. The method of claim 14 wherein cyan ink is printed in one pass in a first direction prior to printing said black ink thereon and magenta ink is printed in an opposite pass in a second direction prior to printing said black ink thereon.

16. The method of claim 13 wherein said surfactant is present in said color ink in a concentration ranging from about 0.2 to 5 wt %.

17. The method of claim 16 wherein said concentration is about 2 wt %.

18. The method of claim 16 wherein said color ink has a surface tension within a range of about 15 dynes/cm up to that of said black ink.

19. The method of claim 13 wherein said black ink has a surface tension of at least that of said color ink.

20. The method of claim 13 wherein said color ink is printed in said first pass and said black ink is subsequently printed in said first pass, in either direction.

21. The method of claim 13 wherein said color ink is printed in said first pass and said black ink is subsequently printed in a second pass.

22. The method of claim 13 wherein said at least one water-soluble color dye in said color ink is anionic and wherein said at least one black pigment in said black ink is cationic.

23. The method of claim 13 wherein six volumes of said black ink are printed over said area.