Urethanes used as additives in a photopolymer formulation
View Patent ↗The invention relates to a photopolymer formulation comprising matrix polymers, writing monomers and photo initiators, to a method for producing said photopolymer formulation, a photopolymer formulation obtained according to said method, a sheeting, a film, a layer, a layer structure or a moulded body made from said photopolymer formulation and to the use of said photopolymer formulation for producing optical elements, in particular for producing holographic elements and images.
1. A photopolymer formulation comprising matrix polymers, writing monomers and photoinitiators, wherein the photopolymer formulation further comprises urethanes as plasticizers, wherein the urethanes have a molecular weight of less than or equal to 250 g/mol, wherein the matrix polymers comprise polyurethanes and wherein the urethanes consists of aliphatic urethanes having the formula (I),
Wherein R 1 and R 2 are independent of one another, represent a linear or branched (C 1 -C 20 )-alkyl radical and R 3 is hydrogen.
2. The photopolymer formulation according to claim 1 , wherein the polyurethanes are obtained by reacting an isocyanate component and an isocyanate-reactive component.
3. The photopolymer formulation according to claim 1 , wherein the writing monomers comprise acrylates.
4. The photopolymer formulation according to claim 1 , wherein the writing monomers comprise urethane acrylates.
5. The photopolymer formulation according to claim 1 , wherein the urethanes have a molecular weight of less than or equal to 200 g/mol.
6. The photopolymer formulation according to claim 1 , wherein the urethanes have a molecular weight of less than or equal to 190 g/mol.
7. The photopolymer formulation according to claim 1 , wherein R 1 represents a linear or branched (C1-C8)-alkyl radical and/or R 2 represents a linear or branched (C1-C8)-alkyl radical.
8. The photopolymer formulation according to claim 1 , wherein R 1 represents a linear or branched (C1-C4)-alkyl radical and/or R 2 represents a linear or branched (C1-C6)-alkyl radical.
9. The photopolymer formulation according to claim 1 , wherein the urethanes have substantially no free NCO groups.
10. The photopolymer formulation according to claim 1 , wherein the photopolymer formulation consists essentially of 15 to 79% by weight of matrix polymers, 5 to 50% by weight of writing monomers, 1 to 10% by weight of photoinitiators and 5 to 50% by weight of urethanes and 0 to 10% by weight of further additives, wherein the sum of the constituents being 100% by weight.
11. The photopolymer formulation according to claim 1 , wherein the photopolymer formulation consists essentially of 30 to 60% by weight of matrix polymers, 10 to 40% by weight of writing monomers, 1 to 3% by weight of photoinitiators and 10 to 40% by weight of urethanes and 0 to 10% by weight of further additives, wherein the sum of the constituents being 100% by weight.
12. A process for the preparation of the photopolymer formulation according to claim 1 , wherein the process comprises mixing the matrix polymers, writing monomers, photoinitiators and urethanes as plasticizers to foam a photopolymer formulation.
13. A sheet, film, layer, layer structure or moulding comprising the photopolymer formulation according to claim 1 .
14. Holographic elements and/or images formed from the photopolymer formulation according to claim 1 .