Photoinitiators for photopolymers
View Patent ↗The present invention relates to novel photopolymer formulation comprising a polyol component, a polyisocyanate component, a writing monomer and a photoinitiator comprising a dye of formula (I). The present invention further relates to a holographic medium which contains a photopolymer formulation of the present invention or is obtainable by using same, to the use of a photopolymer formulation of the present invention for producing holographic media and also to a process for producing a holographic medium by using a photopolymer formulation of the present invention.
1. A photopolymer formulation comprising a polyol component, a polyisocyanate component, a writing monomer and a photoinitiator, wherein the photoinitiator contains a dye of general formula (I),
wherein
A represents N,
E represents boron, and substituted with two halogen radicals or with one radical selected from oxygen and sulphur, and
R 1 and R 3 each independently represent an optionally substituted aromatic radical, and
R 2 represent hydrogen, halogen, cyano, nitro, optionally fluorinated alkoxy or an optionally substituted aromatic, aliphatic or araliphatic radical.
2. The photopolymer formulation according to claim 1 , wherein the dye has a water imbibition of ≦5%.
3. The photopolymer formulation according to claim 2 , wherein the dye has a water inhibition of ≦3%.
4. The photopolymer formulation according to claim 3 , wherein the dye has a water inhibition of ≦2%.
5. The photopolymer formulation according to claim 1 , wherein R 2 represent hydrogen, halogen, cyano, nitro, optionally fluorinated alkoxy or an optionally halogen-substituted aromatic, aliphatic or araliphatic radical.
6. The photopolymer formulation according to claim 5 wherein R 2 represent hydrogen or an optionally halogen-substituted aromatic radical.
7. The photopolymer formulation according to claim 1 , wherein the polyisocyanate component is an aliphatic and/or cycloaliphatic polyisocyanate or a prepolymer with primary NCO groups.
8. The photopolymer formulation according to claim 1 , wherein the polyol component is an at least difunctional polyether, polyester or a polyether-polyester block copolyester with primary OH functions.
9. The photopolymer formulation according to claim 1 , wherein the writing monomer comprises one or more than one monofunctional and/or multifunctional urethane(meth)acrylate.
10. The photopolymer formulation according to claim 1 , wherein the photoinitiator contains one or more than one coinitiator.
11. The photopolymer formulation according to claim 1 , additionally comprising a plasticizer.
12. The photopolymer formulation according to claim 11 , wherein the plasticizer conforms to general formula (III)
where m is ≧1 and ≦8 and R 6 , R 7 , R 8 are independently hydrogen, linear, branched, cyclic or heterocyclic unsubstituted or optionally heteroatom-substituted organic radicals.
13. The photopolymer formulation of claim 12 , wherein at least one of R 6 , R 7 , R 8 is substituted with at least a fluorine atom.
14. The photopolymer according to claim 13 , wherein R 6 is an organic radical comprising at least one fluorine atom.
15. A holographic medium containing a photopolymer formulation according to claim 1 , wherein the photopolymer formulation is coated on a substrate.
16. The holographic medium according to claim 14 , in the form of a film.
17. A method comprising providing a holographic medium according to claim 15 and recording an in-line, off-axis, full-aperture transfer, white light transmission, Denisyuk, off-axis reflection or edge-lit hologram, or an holographic stereogram in said holographic medium.
18. A method for producing a holographic medium comprising providing a photopolymer formulation according to claim 1 .