Enhancement of ink jet image waterfastness with overprinting

• US 20030092796A1
• Filed: 10/23/2002
• Published: 05/15/2003
• Est. Priority Date: 05/16/2000
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Tsao, Yi-Hua, Doumaux, Howard A.
• Granted Patent: US 6,830,326 B2
• Time in Patent Office: Days
• US Class Current: 523/160
• CPC Class Codes: B41J 11/0015 for treating before, during or after printing or for uniform coating or laminating the copy material before or after printing selective coating B41J2/2114
• 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

Abstract

In a four pen ink jet printer comprising cyan, yellow, magenta, and black inks, a clear liquid is applied to printed ink on a print medium via a fifth pen, thereby fixing the colorants, which in turn improves the durability of the printed ink. The clear fixer fluid comprises at least one organic acid and, optionally, a salt of at least one polymeric acid.

Claims

1. A clear fixer fluid for fixing printed ink printed by an ink jet printer, said printed ink comprising an ink composition that would precipitate or flocculate at a pH of about 6 or less, said fixer fluid comprising at least one organic acid and, optionally, a salt of at least one polymeric acid.

2. The fixer fluid of claim 1 wherein said organic acid is selected from the group consisting of mono-functional, di-functional, and poly-functional organic acids.

3. The fixer fluid of claim 2 wherein said organic acid is present in said fixer fluid in a concentration within a range of about 1 to 15 wt %.

4. The fixer fluid of claim 3 wherein said organic acid is present in said fixer fluid in a concentration within a range of about 2 to 7 wt %.

5. The fixer fluid of claim 2 wherein said organic acid is selected from the group consisting of acetic, glycolic, malonic, malic, maleic, ascorbic, succinic, glutaric, fumaric, citric, tartaric, lactic, sulfonic, and ortho-phosphoric acid and derivatives thereof.

6. The fixer fluid of claim 5 wherein said organic acid is selected from the group consisting of succinic acid, citric acid, and glycolic acid.

7. The fixer fluid of claim 1 wherein said polymeric acid is selected from the group consisting of polyacrylic acid, polyvinyl phosphonic acid, polymers with phosphate groups, polystyrene sulfonic acid, and polymers containing sulfonate or carboxylate groups.

8. The fixer fluid of claim 7 wherein said salt comprises a cation associated with said polymeric acid and wherein said cation is selected from the group consisting of sodium, ammonium, and potassium.

9. The fixer fluid of claim 1 wherein polymeric acid is present in said fixer fluid in a concentration within a range of about 1 to 10 wt %.

10. The fixer fluid of claim 1 wherein said fixer fluid has a pH within a range of about 2 to 5.

11. A method of fixing a printed ink printed by an ink jet printer, said printed ink comprising an ink composition that would precipitate or flocculate at a pH of about 6 or less, said method comprising:

(a) printing at least one ink on a print medium, said at least one ink containing a pigment to form a pigment-based ink; and

(b) overprinting said ink with a clear fixer fluid comprising at least one organic acid and, optionally, a salt of at least one polymeric acid.

12. The method of claim 11 wherein said organic acid is selected from the group consisting of mono-functional, di-functional, and poly-functional organic acids.

13. The method of claim 12 wherein said organic acid is present in said fixer fluid in a concentration within a range of about 1 to 15 wt %.

14. The method of claim 13 wherein said organic acid is present in said fixer fluid in a concentration within a range of about 2 to 7 wt %.

15. The method of claim 12 wherein said organic acid is selected from the group consisting of acetic, glycolic, malonic, malic, maleic, ascorbic, succinic, glutaric, fumaric, citric, tartaric, lactic, sulfonic, and ortho-phosphoric acid and derivatives thereof.

16. The method of claim 15 wherein said organic acid is selected from the group consisting of succinic acid, citric acid, and glycolic acid.

17. The method of claim 11 wherein said polymeric acid is selected from the group consisting of polyvinyl phosphonic acid, polymers with phosphate groups, polystyrene sulfonic acid, and polymers containing sulfonate or carboxylate groups.

18. The method of claim 17 wherein said salt comprises a cation associated with said polymeric acid and wherein said cation is selected from the group consisting of sodium, ammonium, and potassium.

19. The method of claim 11 wherein polymeric acid is present in said fixer fluid in a concentration within a range of about 1 to 10 wt %.

20. The method of claim 11 wherein said fixer has a pH within a range of about 2 to 5.

21. The method of claim 11 wherein said ink jet printer includes four pens, each containing an ink, at least one of said inks containing said pigment and a fifth pen containing said clear fixer fluid.

22. The method of claim 21 wherein said overprinting is performed by over-printing said at least one pigment-based ink with said fixer fluid by advancing said print medium a few dot rows per print swath and either

(i) applying said fixer fluid to said at least one pigment-based ink on an N^th pass where said fixer fluid pen trails said at least one ink-printing pen, or

(ii) printing an additional swath without an advance of said print medium with said fixer fluid where said fixer fluid pen leads said at least one ink-printing pen.