Printing process

• US 8,764,177 B2
• Filed: 10/27/2010
• Issued: 07/01/2014
• Est. Priority Date: 10/30/2009
• Status: Expired due to Fees

• Current Assignee: FUJIFILM Imaging Colorants Limited (Fujifilm Holdings Corporation)
• Original Assignee: FUJIFILM Imaging Colorants Limited (Fujifilm Holdings Corporation)
• Inventors: Annable, Tom, Mayall, John
• Primary Examiner(s): MARTIN, LAURA E
• Application Number:
  US13/502,553
• Publication Number:
  US 20120212538A1
• Time in Patent Office: 1,343 Days
• Field of Search: 347/100
• US Class Current: 347/100
• CPC Class Codes: C09D 11/326 characterised by the pigment dispersant

Abstract

A process for printing an image on a substrate comprising the steps of: (a) applying an ink comprising polymer-encapsulated pigment particles and an aqueous medium to a substrate by means of an ink jet printer, wherein (i) the said particles are dispersed in the aqueous medium, and (ii) the said particles comprise a carboxy-functional dispersant crosslinked around a pigment core by a first crosslinking agent; and (b) crosslinking the polymer-encapsulated pigment particles with a second crosslinking agent. The process is particularly useful for printing polymeric substrates which come into contact with rubbing and/or moisture.

Claims

1. A process for printing an image on a substrate comprising the steps of:

(a) applying an ink comprising polymer-encapsulated pigment particles and an aqueous medium to a substrate by means of an ink jet printer, wherein

(i) the said particles are dispersed in the aqueous medium, and

(ii) the said particles comprise a carboxy-functional dispersant crosslinked around a pigment core by a first crosslinking agent; and

(b) crosslinking the polymer-encapsulated pigment particles with a second crosslinking agent, wherein the second crosslinking agent crosslinks the polymer-encapsulated pigment particles by the formation of permanent covalent bonds between the crosslinking agent and the polymer-encapsulated pigment particles.

2. The process according to claim 1 wherein the first crosslinking agent has at least two epoxy groups.

3. The process according to claim 2 wherein the dispersant, prior to crosslinking, has an acid value of from 135 to 250 mg KOH/g.

4. The process according to claim 1 wherein the ink further comprises the second crosslinking agent.

5. The process according to claim 4 wherein the second crosslinking agent has two or more groups selected from the group consisting of epoxy, oxetane, carbodiimide, hydrazide, oxazoline, aziridine, isocyanate, N-methylol, keteneimine and isocyanurate groups.

6. The process according to claim 1 wherein the first contact between the ink and the second crosslinking agent is (a) in flight as they are jetted from different nozzles onto the substrate;

or (b) on the substrate.

7. The process according to claim 1 wherein the crosslinking in step (b) is triggered by heat, by a change in pH, by evaporation of the aqueous medium, by the chemical nature of the substrate or by application of a chemical triggering agent which increases the reactivity of the second crosslinking agent.

8. The process according to claim 7 wherein the second crosslinking agent has two or more groups selected from the group consisting of epoxy, oxetane, carbodiimide, hydrazide, oxazoline, aziridine, isocyanate, N-methylol, keteneimine and isocyanurate groups.

9. The process according to claim 6 wherein the amount of crosslinking agent applied to the substrate exceeds the amount required to react with all carboxy groups present on the polymer-encapsulated pigment particles.

10. The process according to claim 1 which further comprises the step of heating the printed substrate.

11. The process according to claim 1 wherein the first crosslinking agent comprises a water-dispersing group and the second crosslinking agent is free from water-dispersing groups.

12. The process according to claim 1 wherein the second crosslinking agent has two or more groups selected from the group consisting of epoxy, oxetane, carbodiimide, hydrazide, oxazoline, aziridine, isocyanate, N-methylol, keteneimine and isocyanurate groups.

13. The process according to claim 1 wherein the substrate has been roughened or the substrate comprises an ink receptive coating.

14. The process according to claim 13 wherein the ink receptive coating comprises a hydrophilic polymer and a hydrophobic polymer.

15. An ink jet printer comprising

(a) a first chamber and an ink, wherein said ink is present in the first chamber;

and

(b) a second chamber comprising a pigment-free formulation comprising a crosslinking agent and an aqueous medium;

wherein the ink comprises polymer-encapsulated pigment particles and an aqueous medium wherein

(i) the said particles are dispersed in the aqueous medium; and

(ii) the said particles comprise a carboxy-functional dispersant crosslinked around a pigment core by a crosslinking agent.

16. The ink jet printer according to claim 15 which further comprises a means for heating a substrate to which the ink and the pigment-free formulation have been applied.

17. An ink jet printer cartridge comprising:

(a) a first chamber and an ink, wherein said ink is present in the first chamber; and

(b) a second chamber comprising a pigment-free formulation comprising a crosslinking agent and an aqueous medium;

wherein the ink comprises polymer-encapsulated pigment particles and an aqueous medium wherein

(i) the said particles are dispersed in the aqueous medium; and

(ii) the said particles comprise a carboxy-functional dispersant crosslinked around a pigment core by a crosslinking agent.