Printing ink
Inks are disclosed which are used in ink-jet printing. The inks are cured by ultraviolet radiation, preferably free radical initiation. The inks contain a (meth)acrylate monomer, an α,β-unsaturated ether monomer and a photoinitiator. The inks exhibit a low viscosity and give tough printed images after curing.
1. An ink jet ink which is essentially free of water and/or volatile organic solvents, including at least one multifunctional (meth)acrylate monomer, at least one α,β-unsaturated ether monomer, at least one radical photoinitiator and at least one dispersible pigment, wherein the ink includes, by weight, from 2 to 15 parts of multifunctional (meth)acrylate monomer to 1 part of α,β-unsaturated ether monomer, the ink having a viscosity of less than 50 mPas at 25° C. and wherein the α,β-unsaturated ether monomer is present in an amount from 1 to 30% by weight of the ink.
2. An ink jet ink as claimed in claim 1 , wherein the multifunctional (meth)acrylate monomer is present in an amount from 50 to 95% by weight of the ink.
3. An ink jet ink as claimed in claim 1 or 2 , wherein the ink is essentially free from monofunctional (meth) acrylate monomers.
4. The ink jet ink of claim 2 wherein the multi-functional (meth) acrylate monomer is an alkaline glycol di(meth) acrylate and the α,β-unsaturated ether is a glycol divinyl ether and the dispersible pigment is present from 1 to 20% by weight of the ink.
5. The ink-jet ink of claim 4 which further comprises an oligomer.
6. An ink jet ink as claimed in claim 3 , wherein the photoinitiator is a free radical photoinitiator, selected from benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-(4-morpholinophenyl)butan-1-one, benzil dimethylketal, bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide or mixtures thereof.
7. An ink jet ink as claimed in claim 6 , wherein the photoinitiator is present from 1 to 20% by weight of the ink.
8. An ink-jet ink as claimed in claim 6 , wherein the dispersible pigment is present from 0.5 to 15% by weight of the ink.
9. An ink jet ink as claimed in claim 3 , wherein the photoinitiator is present from 1 to 20% by weight of the ink.
10. An ink-jet ink as claimed in claim 9 , wherein the dispersible pigment is present from 0.5 to 15% by weight of the ink.
11. An ink-jet ink as claimed in claim 3 , wherein the dispersible pigment is present from 0.5 to 15% by weight. of the ink.
12. A method of ink jet printing, wherein the method uses the ink jet ink as claimed in claim 3 .
13. An ink jet ink as claimed in claim 1 , wherein the vinyl ether is selected from triethylene glycol divinyl ether, diethylene glycol divenyl ether, 1,4-cyclohexanedimethanol divinyl ether, ethylene glycol monovinyl ether and mixtures thereof.
14. An ink jet ink as claimed in claim 13 , wherein the photoinitiator is a free radical photoinitiator, selected from benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-(4-morpholinophenyl)butan-1-one, benzil dimethylketal, bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide or mixtures thereof.
15. An ink jet ink as claimed in claim 13 , wherein the photoinitiator is present from 1 to 20% by weight of the ink.
16. An ink-jet ink as claimed in claim 13 , wherein the dispersible pigment is present from 0.5 to 15% by weight of the ink.
17. An ink jet ink as claimed in claim 1 , wherein the photoinitiator is a free radical photoinitiator, selected from benzophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-(4-morpholinophenyl)butan-1-one, benzil dimethylketal, bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide or mixtures thereof.
18. An ink jet ink as claimed in claim 1 , wherein the photoinitiator is present from 1 to 20% by weight of the ink.
19. An ink-jet ink as claimed in claim 1 , wherein the dispersible pigment is present from 0.5 to 15% by weight of the ink.