INK SET INCLUDING A PRE-TREATMENT FIXING FLUID AND A FIXABLE, UV CURABLE INK

• US 20160304734A1
• Filed: 01/28/2014
• Published: 10/20/2016
• Est. Priority Date: 01/28/2014
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Keane, Daniel Vincent, Feng, Yi, Bi, Yubai, Emamjomeh, Ali
• Granted Patent: US 9,777,179 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 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 7/0081 using electromagnetic radiation or waves, e.g. ultraviolet radiation, electron beams
• CPC Class Codes: C09D 11/101 Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing
• CPC Class Codes: C09D 11/102 containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
• CPC Class Codes: C09D 11/326 characterised by the pigment dispersant
• CPC Class Codes: C09D 11/36 based on non-aqueous solvents
• CPC Class Codes: C09D 11/40 Ink-sets specially adapted for multi-colour inkjet printing
• CPC Class Codes: C09D 11/54 Inks based on two liquids, one liquid being the ink, the other liquid being a reaction solution, a fixer or a treatment solution for the ink

Abstract

An ink set includes a pre-treatment fixing fluid including at least two metal salts and a fixable, ultraviolet (UV) curable ink. The UV curable ink includes an aqueous ink vehicle, a pigment dispersed in the aqueous ink vehicle, and a dispersant. A polyurethane polymer dispersion is suspended as droplets within the aqueous ink vehicle. The polyurethane polymer dispersion includes a polyurethane polymer selected from the group consisting of a polyether-based polyurethane, a polyester-based poly-urethane, a polycarbonate-based polyurethane, and mixtures thereof. The polyurethane polymer has i) an acid number ranging from 0 mg/g to less than 20 mg/g and ii) a glass transition temperature of less than 0 C. A water soluble or water dispersible photoinitiator is present in the pre-treatment fixing fluid or in the fixable, UV curable ink.

Claims

1. An ink set, comprising:

a pre-treatment fixing fluid including at least two metal salts; and

a fixable, ultraviolet (UV) curable ink including;

an aqueous ink vehicle;

a pigment dispersed in the aqueous ink vehicle;

a dispersant; and

a polyurethane polymer dispersion suspended as droplets within the aqueous ink vehicle, the polyurethane polymer dispersion including a polyurethane polymer selected from the group consisting of a polyether-based polyurethane, a polyester-based polyurethane, a polycarbonate-based polyurethane, and mixtures thereof, and the polyurethane polymer having i) an acid number ranging from 0 mg/g to less than 20 mg/g and ii) a glass transition temperature of less than 0°

C.;

wherein a water soluble or water dispersible photoinitiator is present in the pre-treatment fixing fluid or in the fixable, UV curable ink.

2. The ink set as defined in claim 1 wherein:

an amount of the pigment in the fixable, UV curable ink ranges from about 1 wt % to about 5 wt % of a total wt % of the fixable, UV curable ink; and

an amount of the polyurethane polymer ranges from about 3 wt % to about 20 wt % of the total wt % of the fixable, UV curable ink.

3. The ink set as defined in claim 1 wherein the polyurethane polymer has a weight average molecular weight ranging from about 1000 to about 10,000.

4. The ink set as defined in claim 1 wherein the fixable, UV curable ink further includes a sufficient amount of a base to render a pH of the fixable, UV curable ink from about 7.5 to about 9.5.

5. The ink set as defined in claim 1 wherein the photoinitiator is present in the fixable, UV curable ink an amount of 2 wt % or less of a total wt % of the fixable, UV curable ink.

6. The ink set as defined in claim 1 wherein the pigment is selected from the group consisting of Pigment Yellow 74, quinacridone-based magenta pigments, Pigment Blue 15:

3, and carbon black.

7. The ink set as defined in claim 1 wherein the aqueous ink vehicle consists of:

a co-solvent selected from the group consisting of N-(2-Hydroxyethyl)-2-pyrrolidone, 2-Methyl-1,3-Propanediol, 2-pyrrolidone, a mixture of 2-Methyl-1,3-Propanediol and isopropanol, and combinations thereof;

a non-ionic surfactant;

an anti-kogation agent;

a buffer;

optionally a biocide; and

a balance of water.

8. The ink set as defined in claim 1 wherein the pre-treatment fixing fluid includes:

calcium propionate and calcium pantothenate as the at least two metal salts;

tetraethylene glycol;

a surfactant;

a biocide;

an acid in an amount sufficient to render a pH of the pre-treatment fixing fluid from about 4.0 to about 7.0; and

a balance of water.

9. The ink set as defined in claim 1 wherein the polyurethane polymer is less reactive than the pigment with components in the pre-treatment fixing fluid.

10. A method, comprising:

applying onto a medium a pre-treatment fixing fluid including at least two metal salts;

while the pre-treatment fixing fluid is still wet on the medium, depositing a fixable, UV curable ink onto the medium, the fixable, UV curable ink including;

an aqueous ink vehicle;

a pigment dispersed in the aqueous ink vehicle;

a dispersant; and

a polyurethane polymer dispersion suspended as droplets within the aqueous ink vehicle, the polyurethane polymer dispersion including a polyurethane polymer selected from the group consisting of a polyether-based polyurethane, a polyester-based polyurethane, a polycarbonate-based polyurethane, and mixtures thereof, and the polyurethane polymer having i) an acid number ranging from 0 mg/g to less than 20 mg/g and ii) a glass transition temperature of less than 0°

C.;

wherein a water soluble or water dispersible photoinitiator is present in the pre-treatment fixing fluid or in the fixable, UV curable ink;

drying the applied pre-treatment fixing fluid and the deposited fixable, UV curable ink; and

exposing the dried, deposited fixable, UV curable ink to UV radiation, thereby cross-linking the polyurethane polymer.

11. The method as defined in claim 10 wherein prior to the depositing, the method further comprises forming the fixable, UV curable ink by:

adding additional water to the polyurethane polymer dispersion, which includes water and the polyurethane polymer dispersed therein;

adding any of a co-solvent, an anti-kogation agent, a non-ionic surfactant, or a biocide to the diluted polyurethane dispersion;

adding a pigment dispersion to the diluted polyurethane dispersion, thereby forming the fixable, UV curable ink, the pigment dispersion including the pigment and the dispersant dispersed in water; and

adjusting a pH of the fixable, UV curable ink.

12. The method as defined in claim 10 wherein the exposing is accomplished with a UV light emitting diode (LED) lamp.

13. The method as defined in claim 10 wherein:

the applying of the pre-treatment fixing fluid includes jetting, with a thermal inkjet printer, the pre-treatment fixing fluid from a first inkjet ink cartridge; and

the depositing of the fixable, UV curable ink includes jetting, with the thermal inkjet printer, the ink from a second inkjet ink cartridge.

14. A fixable, ultraviolet (UV) curable ink, consisting of:

an aqueous ink vehicle including water and a co-solvent;

a pigment;

a neutralized acrylic acid dispersant;

a polyurethane polymer dispersion suspended as droplets within the aqueous ink vehicle, the polyurethane polymer dispersion including a polyurethane polymer selected from the group consisting of a polyether-based polyurethane, a polyester-based polyurethane, a polycarbonate-based polyurethane, and mixtures thereof, and the polyurethane polymer having i) an acid number ranging from 0 mg/g to less than 20 mg/g and ii) a glass transition temperature of less than 0°

C.;

a water soluble or water dispersible photoinitiator; and

optionally an additive selected from the group consisting of a biocide, a non-ionic surfactant, an anti-kogation agent, a buffer, and combinations thereof.

15. The fixable, UV curable ink as defined in claim 14 wherein:

an amount of the pigment in the fixable, UV curable ink ranges from about 1 wt % to about 5 wt % of a total wt % of the fixable, UV curable ink; and

an amount of the polyurethane polymer ranges from about 3 wt % to about 20 wt % of the total wt % of the fixable, UV curable ink.