Method for the production of flexographic printing forms by means of electron beam cross-linking and laser engraving

1. A process for the production of flexographic printing plates by means of laser engraving, comprising the following steps:

a) application of at least one elastomeric relief layer to a dimensionally stable substrate, the relief layer comprising at least one elastomeric binder and at least one absorber for laser radiation,

b) uniform crosslinking of the relief layer,

c) engraving of a printing relief into the crosslinked relief layer by means of a laser,

wherein the uniform crosslinking is carried out by means of electron beams in a minimum total dose of 40 kGy.

2. A process as claimed in claim 1 , wherein, in a step (a′), an upper layer having a thickness of not more than 100 μm is furthermore applied, the upper layer comprising at least one polymeric binder.

3. A process as claimed in claim 1 , wherein the electron beams have an energy of at least 2 MeV.

4. A process as claimed in claim 1 , wherein the total dose of electron beams is distributed over two or more part-doses.

5. A process as claimed in claim 4 , wherein the irradiation is stopped for an irradiation pause after the administration of any part-dose.

6. A process as claimed in claim 4 , wherein the energy of the electron beam is identical for each of the administered part-doses.

7. A process as claimed in claim 4 , wherein the energy of the electron beam for at least one of the administered part-doses differs from that of the other part-doses.

8. A process as claimed in claim 4 , wherein the energy of the electron beam differs for all administered part-doses.

9. A process as claimed in claim 8 , wherein the initial part-dose is the one in which the electron beam has the highest energy, and the energy for each further part-dose decreases stepwise.

10. A process as claimed in claim 4 , wherein at least one of the part-doses has an energy of at least 2 MeV.

11. A process as claimed in claim 1 , wherein a total dose of 200 kGy is not exceeded.

12. A process as claimed in claim 1 , wherein a total dose of 150 kGy is not exceeded.

13. A process as claimed in claim 1 , wherein the irradiation is carried out using electrons in air.

14. A process as claimed in claim 1 , wherein the elastomeric binder has ethylenically unsaturated groups.

15. A process as claimed in claim 1 , wherein the elastomeric binder has functional groups crosslinkable under the action of electron beams.

16. A process as claimed in claim 15 , wherein the functional groups are protic groups.

17. A process as claimed in claim 1 , wherein the elastomeric binder has ethylenically unsaturated groups and functional groups crosslinkable under the action of electron beams.

18. A process as claimed in claim 1 , wherein a mixture of at least one elastomeric binder which has no functional groups with at least one further binder which has functional groups is used.

19. A process as claimed in claim 1 , wherein the relief layer furthermore comprises at least one low molecular weight or oligomeric compound crosslinkable by means of electron beams.

20. A process as claimed in claim 19 , wherein the low molecular weight compound is an ethylenically unsaturated monomer.

21. A process as claimed in claim 19 , wherein the low molecular weight or oligomeric compound is a compound having functional groups.

22. A process as claimed in claim 21 , wherein the functional groups are protic groups.

23. A process as claimed in claim 1 , wherein the elastomeric binder is a thermoplastic elastomeric binder and the relief layer is produced by extrusion followed by calendering.

24. A process as claimed in claim 1 , wherein the relief layer is opaque.

25. A process as claimed in claim 1 , wherein the laser engraving (c) is carried out using a laser having a wavelength of 600-2000 nm.

26. A process as claimed in claim 25 , wherein the laser engraving (c) is carried out using an Nd-YAG laser.

27. A flexographic printing plate obtainable as claimed in claim 1 .