Flexible, scratch resistant radiation curable inkjet inks

1. A free radical radiation curable inkjet ink comprising:

a photoinitiator; and

polymerizable compounds including at least 45 wt % of a mixture of monomers consisting of:

a) 10 to 35 wt % of one or more cyclic monofunctional acrylates wherein a homopolymer thereof has a T g larger than 20° C.;

b) 10 to 30 wt % of a N-vinyl lactam and/or a vinylether acrylate; and

c) 10 to 30 wt % of an ethoxylated and/or propoxylated polyacrylate having a molecular weight of at least 450; wherein

all wt % are based on a total weight of the free radical radiation curable inkjet ink; and

the T g is determined by the DSC method in ISO 11357-2:1999.

2. The free radical radiation curable inkjet ink according to claim 1 , wherein the vinylether acrylate is 2-(vinyloxyethoxy)ethyl acrylate.

3. The free radical radiation curable inkjet ink according to claim 1 , wherein the N-vinyl lactam is N-vinyl caprolactam.

4. The free radical radiation curable inkjet ink according to claim 2 , wherein the N-vinyl lactam is N-vinyl caprolactam.

5. The free radical radiation curable inkjet ink according to claim 1 , wherein the one or more cyclic monofunctional acrylates are present in the free radical radiation curable inkjet ink in an amount between 15 wt % and 30 wt %.

6. The free radical radiation curable inkjet ink according to claim 1 , wherein the N-vinyl lactam and/or vinylether acrylate is present in the free radical radiation curable inkjet ink in an amount between 15 wt % and 25 wt %.

7. The free radical radiation curable inkjet ink according to claim 5 , wherein the N-vinyl lactam and/or vinylether acrylate is present in the free radical radiation curable inkjet ink in an amount between 15 wt % and 25 wt %.

8. The free radical radiation curable inkjet ink according to claim 1 , wherein the ethoxylated and/or propoxylated multifunctional acrylate is present in the free radical radiation curable inkjet ink in an amount between 15 wt % and 25 wt %.

9. The free radical radiation curable inkjet ink according to claim 7 , wherein the ethoxylated and/or propoxylated multifunctional acrylate is present in the free radical radiation curable inkjet ink in an amount between 15 wt % and 25 wt %.

10. The free radical radiation curable inkjet ink according to claim 1 , wherein an amount of all polymerizable compounds is higher than 80 wt % based on the total weight of the free radical radiation curable inkjet ink.

11. The free radical radiation curable inkjet ink according to claim 1 , wherein the free radical radiation curable inkjet ink has a viscosity of less than 20 mPa·s at 45° C. and at a shear rate of 1,000 s −1 .

12. The free radical radiation curable inkjet ink according to claim 1 , wherein the one or more cyclic monofunctional acrylates are selected from the group consisting of 4-tert.butylcyclohexylacrylate and isobornyl acrylate.

13. The free radical radiation curable inkjet ink according to claim 1 , further comprising a urethane acrylate.

14. The free radical radiation curable inkjet ink according to claim 1 , wherein the free radical radiation curable inkjet ink includes no organic solvent or water.

15. The free radical radiation curable inkjet ink according to claim 1 , wherein the free radical radiation curable inkjet ink is a colorless liquid.

16. A free radical radiation curable inkjet ink set comprising:

at least two different free radical radiation curable inkjet inks as defined by claim 1 .

17. An inkjet printing method comprising the steps of:

providing a substantially non-absorbing ink-receiver;

providing a free radical radiation curable inkjet ink as defined by claim 1 ; and

inkjet printing the free radical radiation curable inkjet ink on the substantially non-absorbing ink-receiver.