Fluorourethane as an additive in a photopolymer formulation
View Patent ↗The invention relates to a photopolymer formulation comprising matrix polymers, writing monomers, and photoinitiators, to the use of the photopolymer formulation for producing optical elements, in particular for producing holographic elements and images, to a method for illuminating holographic media made of the photopolymer formulation, and to special fluorourethanes.
1. A photopolymer formulation comprising matrix polymers, writing monomers and photoinitiators, wherein the photopolymer formulation further comprises fluorourethanes as plasticizers, wherein the matrix polymers comprise polyurethanes and wherein the photopolymer formulation consists essentially of 15 to 79% by weight of matrix polymers, 5 to 50% by weight of acrylate writing monomers having a refractive index of n d 20 >1.50, 1 to 10% by weight of photoinitiators, between 5 and 40% by weight of fluorourethanes and 0 to 10% by weight of further additives, wherein the sum of the constituents being 100% by weight.
2. The photopolymer formulation according to claim 1 , wherein the fluorourethanes comprise compounds having the formula (II)
wherein
n is from 1 to 8 and
R 1 , R 2 , R 3 represent, independently of one another, hydrogen or linear, branched, cyclic or heterocyclic organic radicals which are unsubstituted or optionally also substituted by heteroatoms, at least one of the radicals R 1 , R 2 , R 3 being substituted by at least one fluorine atom.
3. The photopolymer formulation according to claim 2 , wherein R 1 represents an organic radical having at least one fluorine atom.
4. The photopolymer formulation according to claim 2 , wherein R 1 comprises 1-20 CF 2 groups and/or one or more CF 3 groups, R 2 comprises a C1-C20 alkyl radical or hydrogen, and R 3 comprises a C1-C20 alkyl radical or hydrogen.
5. The photopolymer formulation according to claim 2 , wherein R 1 comprises 1-10 CF 2 groups and/or one or more CF 3 groups, R 2 comprises a C1-C10 alkyl radical or hydrogen, and R 3 comprises a C1-C10 alkyl radical or hydrogen.
6. The photopolymer formulation according to claim 2 , wherein R 1 comprises 1-8 CF 2 groups and/or one or more CF 3 groups.
7. The photopolymer formulation according to claim 1 , wherein the fluorourethanes comprise uretdione, isocyanurate, biuret, allophanate, polyurea, oxadiazadione and/or iminooxadiazinedione structural elements and/or mixtures of these structural elements.
8. The photopolymer formulation according to claim 1 , wherein the fluorourethanes have a refractive index n 2 D of ≦1.4600.
9. The photopolymer formulation according to claim 1 , wherein the fluorourethanes have a refractive index n 20 D of ≦1.4300.
10. The photopolymer formulation according to claim 1 , wherein the fluorourethanes have a fluorine content of 10-80% by weight.
11. The photopolymer formulation according to claim 1 , wherein the fluorourethanes have a fluorine content of 17.5-65% by weight.
12. Holographic elements and images formed from the photopolymer formulation according to claim 1 .
13. A method for exposing holographic media comprising the photopolymer formulation according to claim 1 , wherein the method comprises selectively polymerizing the writing monomers with spatial resolution by electromagnetic radiation.