Aqueous resin based inkjet inks
An inkjet ink includes a) an aqueous medium; and b) capsules composed of a polymeric shell surrounding a core; wherein the capsules are dispersed in the aqueous medium using a dispersing group covalently bonded to the polymeric shell; wherein the core contains a photoinitiator and one or more chemical reactants capable of forming a reaction product upon application of UV light; wherein the capsules have an average particle size of no more than 4 μm as determined by dynamic laser diffraction; and wherein the photoinitiator is a diffusion hindered photoinitiator selected from the group consisting of multifunctional photoinitiators, oligomeric photoinitiators, polymeric photoinitiators and polymerizable photoinitiators.
1. An inkjet ink comprising:
an aqueous medium; and
capsules including a polymeric shell surrounding a core; wherein
the aqueous medium includes one or more surfactants selected from the group consisting of fatty acid salts, ester salts of a higher alcohol, alkylbenzene sulphonate salts, sulphosuccinate ester salts and phosphate ester salts of a higher alcohol, ethylene oxide adducts of a higher alcohol, ethylene oxide adducts of an alkylphenol, ethylene oxide adducts of a polyhydric alcohol fatty acid ester, and acetylene glycol adducts and ethylene oxide adducts thereof;
the capsules are dispersed in the aqueous medium by a dispersing group covalently bonded to the polymeric shell;
the core includes a photoinitiator and one or more chemical reactants that form a reaction product upon application of UV light;
the capsules have an average particle size of no more than 4 μm as determined by dynamic laser diffraction;
the photoinitiator is a diffusion hindered photoinitiator selected from the group consisting of multifunctional photoinitiators, oligomeric photoinitiators, polymeric photoinitiators, and polymerizable photoinitiators; and
the dispersing group is selected from the group consisting of a carboxylic acid or salt thereof, a sulfonic acid or salt thereof, a phosphoric acid ester or salt thereof, a phosphonic acid or salt thereof, an ammonium group, a sulfonium group, and a phosphonium group.
2. The inkjet ink according to claim 1 , wherein the polymeric shell includes a polymer selected from the group consisting of a polyamide, a melamine based polymer, a poly(urea-urethane) polymer, and copolymers thereof.
3. The inkjet ink according to claim 1 , wherein the one or more chemical reactants include a monomer, oligomer, or polymer that is curable by free radical polymerization or by cationic polymerization.
4. The inkjet ink according to claim 3 , wherein the monomer, oligomer, or polymer includes at least one acrylate group as a polymerizable group.
5. The inkjet ink according to claim 1 , wherein the photoinitiator is a polymeric photoinitiator or a polymerizable photoinitiator.
6. The inkjet ink according to claim 5 , wherein the photoinitiator includes a polymeric or polymerizable thioxanthone.
7. The inkjet ink according to claim 1 , further comprising an optothermal converting agent.
8. The inkjet ink according to claim 7 , wherein the optothermal converting agent is an infrared dye.
9. The inkjet ink according to claim 1 , further comprising a colorant.
10. The inkjet ink according to claim 1 , wherein the aqueous medium includes a polymeric latex particle.
11. The inkjet ink according to claim 1 , wherein the polymeric shell is crosslinked.
12. An inkjet printing method including the steps of:
jetting an inkjet ink according to claim 1 on a substrate; and
applying UV light to the inkjet ink jetted on the substrate to form a reaction product from the one or more chemical reactants in the capsules.
13. The inkjet printing method according to claim 12 , wherein the substrate is a textile, leather, glass, pharmaceutical packaging, or food packaging.
14. The inkjet printing method according to claim 13 , wherein the step of applying UV light is performed using UV LEDs with a wavelength larger than 360 nm.