Printing ink
This invention relates to an ink-jet ink substantially free of water and volatile organic solvents comprising at least one monofunctional (meth)acrylate monomer, including phenoxyethyl acrylate; at least one monofunctional N-vinyl amide monomer, including N-vinyl caprolactam; 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; at least one monofunctional N-vinyl amide monomer, wherein said at least one monofunctional N-vinyl amide monomer is selected from the group consisting of N-vinyl caprolactam (NVC) and N-vinyl pyrrolidone (NVP); at least one radical photoinitiator; 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 1.1 to 2.0, 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 ink contains no more than 30 wt % of multifunctional monomers based on the total weight of the ink.
4. 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.
5. An ink-jet ink as claimed in claim 1 , wherein the at least one monofunctional (meth)acrylate is selected from the group consisting of phenoxyethyl acrylate (PEA), cyclic TMP formal acrylate (CTFA), isobornyl acrylate (IBOA), tetrahydrofurfuryl acrylate (THFA), 2-(2-ethoxyethoxy}ethyl acrylate, octa/decyl acrylate (ODA), tridecyl acrylate (TDA), isodecyl acrylate (IDA) and lauryl acrylate.
6. An ink-jet ink as claimed in claim 1 , wherein the at least one monofunctional (meth)acrylate is acyclic monofunctional (meth)acrylate.
7. An ink-jet ink as claimed in claim 1 , 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 2.0.
8. An ink-jet ink as claimed in claim 2 , wherein the total amount is at least 70 wt %.
9. An ink-jet ink as claimed in claim 8 , wherein the total amount is at least 80 wt %.
10. An ink-jet ink as claimed in claim 5 , wherein the ink contains a combination of monomers selected from the group consisting of THFA tetrahydrofurfuryl acrylate)/NVC (N-vinyl caprolactam), IBOA (isobornyl acrylate)/NVC (N-vinyl caprolactam), PEA(phenoxyethyl acrylate)/NVC(N-vinyl caprolactam), CTFA (cyclic TMP formal acrylate)/NVC(N-vinyl caprolactam), IBOA(isobornyl acrylate)/ACMO (N-acryloylmorpholine) and IBOA(isobornyl acrylate)/NVP(N-vinyl pyrrolidone).
11. An ink-jet ink as claimed in claim 6 , wherein the ink comprises at least one cyclic monofunctional (meth)acrylate as the sole monofunctional (meth)acrylate(s) present.
12. An ink-jet ink as claimed in claim 6 , wherein the ink contains a combination of monomers selected from the group consisting of THFA (tetrahydrofurfuryl acrylate)/NVC (N-vinyl caprolactam), IBOA (isobornyl acrylate)/NVC (N-vinyl caprolactam), PEA(phenoxyethyl acrylate)/NVC(N-vinyl caprolactam), CTFA (cyclic TMP formal acrylate)/NVC(N-vinyl caprolactam) , IBOA(isobornyl acrylate)/ACMO (N-acryloylmorpholine) and IBOA(isobornyl acrylate)/NVP(N-vinyl pyrrolidone.
13. An ink-jet ink as claimed in claim 6 , wherein the cyclic monofunctional (meth)acrylate is phenoxyethyl acrylate (PEA), cyclic TMP formal acrylate (CTFA), isobornyl acrylate (IBOA), tetrahydrofurfuryl acrylate (THFA), or mixtures thereof.
14. An ink-jet ink as claimed in claim 11 , wherein the cyclic monofunctional (meth)acrylate is phenoxyethyl acrylate (PEA), cyclic TMP formal acrylate (CTFA), isobornyl acrvlate (IBOA), tetrahydrofurfuryl acrylate (THFA), or mixtures thereof.
15. An ink-jet ink as claimed in claim 11 , wherein the ink contains a combination of monomers selected from the group consisting of THFA (tetrahydrofurfulyl acrylate)/NVC(N-vinyl caprolactam), IBOA (isobornyl acrylate)/NVC (N-vinyl caprolactam), PEA(phenoxyethyl acrylate)/NVC(N-vinyl caprolactam),CTFA (cyclic TMP formal acrylate)/NVC(N-vinyl caprolactam), IBOA(isobornyl acrylate)/ACMO (N-acryloylmorpholine) and IBOA(isobornyl acrylate)/NVP(N-vinyl pyrrolidone).
16. A method of ink-jet printing, comprising printing the ink-jet ink as claimed in claim 1 onto a substrate and curing the ink.
17. A substrate having the ink-jet ink as claimed in claim 1 printed thereon.
18. An ink-jet ink cartridge containing the ink-jet ink as claimed in claim 1 .