Radiation curable compositions

1. A radiation curable composition comprising a polymeric co-initiator comprising a dendritic polymer core with at least one co-initiating functional group as an end group, wherein said dendritic polymer core is a hyperbranched polymer core, and wherein said at least one co-initiating functional group is a co-initiating functional group selected from the group consisting of an aliphatic amine, an aromatic amine and a thiol.

2. The radiation curable composition of claim 1 , wherein said radiation curable composition is a radiation curable inkjet ink.

3. The radiation curable composition according to claim 1 , wherein said at least one co-initiating functional group is selected from the group consisting of tertiary amines, heterocyclic thiols, 4-dialkylamino-benzoic acid, and 4-dialkylamino-benzoic acid derivatives.

4. The radiation curable composition according to claim 1 , wherein said polymeric co-initiator includes at least five co-initiating functional groups as end groups on the dendritic polymer core.

5. The radiation curable composition according to claim 1 , wherein said polymeric co-initiator includes at least one other functional group as an end group.

6. The radiation curable composition according to claim 5 , wherein said one other functional group is a compatibilizing group which improves the compatibility of the polymeric co-initiator with a radiation curable composition.

7. The radiation curable composition according to claim 1 , wherein said hyperbranched polymer core has a polydispersity Mw/Mn of less than 3.

8. The radiation curable composition according to claim 1 , wherein said hyperbranched polymer core is a polyglycidol.

9. The process for polymerization of monomers, oligomers and/or prepolymers comprising the steps of:

a) providing a polymeric co-initiator, and

b) mixing the said polymeric co-initiator with monomers, oligomers and/or prepolymers, wherein said polymeric co-initiator comprises a dendritic polymer core with at least one co-initiating functional group as an end group, wherein said dendritic polymer core is a hyperbranched polymer core, and wherein said at least one co-initiating functional group is a co-initiating functional group selected from the group consisting of an aliphatic amine, an aromatic amine and a thiol.

10. The process for polymerization of monomers, oligomers and/or prepolymers according to claim 9 , wherein said hyperbranched polymer core has a polydispersity Mw/Mn of less than 3.

11. The process for polymerization of monomers, oligomers and/or prepolymers according to claim 10 , wherein said hyperbranched polymer core is a polyglycidol.

12. A process for providing an imaged article comprising the steps of:

a) providing a radiation curable inkjet ink, and

b) jetting said radiation curable inkjet ink on an ink jet recording element selected from the group consisting of paper, coated paper, polyolefin coated paper, cardboard, wood, composite boards, plastic, coated plastic, canvas, textile, metal, glasses, plant fibre products, leather, magnetic materials and ceramics,

wherein said imaged article comprises a polymeric co-initiator having a dendritic polymer core with at least one co-initiating functional group as an end group, and wherein said dendritic polymer core is a hyperbranched polymer core, and wherein said at least one co-initiating functional group is a co-initiating functional group selected from the group consisting of an aliphatic amine, an aromatic amine and a thiol.

13. The process for providing an imaged article according to claim 12 , wherein said hyperbranched polymer core has a polydispersity Mw/Mn of less than 3.

14. The process for providing an imaged article according to claim 13 , wherein said hyperbranched polymer core is a polyglycidol.