Printing ink
This invention relates to an ink-jet ink comprising at least one monofunctional (meth)acrylate monomer; at least one monofunctional N-vinyl amide monomer; at least one radical photoinitiator; and at least one coloring agent. The ink has a viscosity of less than 100 mPas at 25° C., and the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is from 1.0 to 6.0.
1. An ink-jet ink substantially free of water and volatile organic solvents comprising at least one monofunctional (meth)acrylate monomer, wherein said at least one monofunctional (meth)acrylate monomer comprises phenoxyethyl acrylate; at least one monofunctional N-vinyl amide monomer, wherein said at least one monofunctional N-vinyl amide monomer comprises N-vinyl caprolactam; at least one radical photoinitiator; and at least one colouring agent; wherein the ink has a viscosity of less than 100 mPas at 25° C., and wherein the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is from 1.2 to 4.0, and further wherein said ink-jet ink has a higher cure speed than a cure speed of an ink-jet ink which comprises only one of the at least one monofunctional (meth)acrylate monomer and the at least one monofunctional N-vinyl amide monomer.
2. An ink-jet ink as claimed in claim 1 , wherein the total amount of the at least one monofunctional (meth)acrylate monomer and the at least one monofunctional N-vinyl amide monomer is at least 60 wt % based on the total weight of the ink.
3. An ink-jet ink as claimed in claim 1 , wherein the upper limit in the ratio is 3.5 or less.
4. An ink-jet ink as claimed in claim 1 , wherein the lower limit in the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is 1.3 or more.
5. An ink-jet ink as claimed in claim 1 , wherein the monofunctional (meth)acrylate monomers present are exclusively cyclic.
6. An ink-jet ink as claimed in claim 1 , wherein the ink contains no more than 30 wt % of multifunctional monomers based on the total weight of the ink.
7. An ink-jet ink as claimed in claim 1 , wherein the ink contains at least one multifunctional monomer and one or more of the multifunctional monomers is a multifunctional (meth)acrylate monomer.
8. An ink-jet ink as claimed in claim 2 , wherein the lower limit in the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is 1.3 or more.
9. An ink-jet ink as claimed in claim 2 , wherein the total amount is at least 70 wt %.
10. An ink-jet ink as claimed in claim 9 , wherein the total amount is at least 80 wt %.
11. An ink-jet ink as claimed in claim 9 , wherein the lower limit in the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is 1.3 or more.
12. An ink-jet ink as claimed in claim 10 , wherein the lower limit in the molar ratio of the at least one monofunctional (meth)acrylate monomer to the at least one monofunctional N-vinyl amide monomer is 1.30 or more.
13. A method of ink-jet printing, comprising printing the ink-jet ink as claimed in claim 1 on to a substrate and curing the ink.
14. A substrate having the ink-jet ink as claimed in claim 1 printed thereon.
15. An ink-jet ink cartridge containing the ink-jet ink as claimed in claim 1 .