Method for producing a holographic film

1. A process for producing holographic films comprising

i) providing a photopolymer formulation comprising:

A) matrix polymers as amorphous network,

B) a combination of a monofunctional writing monomer and a polyfunctional writing monomer,

C) a photoinitiator system,

D) optionally a non-photopolymerizable component, and

E) optionally catalysts, free radical stabilizers, solvents, additives and other auxiliaries and/or additives

ii) determining the plateau modulus G 0 of the photopolymer formulation by measuring the curing of the matrix in an oscillation rheometer, as follows:

Oscillation measuring mode at a constant circular frequency ω 0 of 10 rad/s and a regulated deformation amplitude of 1%;

Temperature 50° C., normal force regulation set at 0 Newton

Recording of the storage modulus G′ over the measuring time up to a constant value Gmax of G′ was reached or for not more than 3 hours; this value is taken as plateau modulus G 0 ;

iii) applying the photopolymer formulation as a film extensively to a substrate, and

iv) drying the film,

wherein the photopolymer formulation has a plateau modulus G 0 of ≧0.03 MPa.

2. The process according to claim 1 , wherein the photopolymer formulation has a plateau modulus of from 0.03 to 1 MPa.

3. The process according to claim 1 , wherein the photopolymer formulation has a plateau modulus of from 0.05 to 1 MPa.

4. The process according to claim 1 , wherein the photopolymer formulation has a plateau modulus of from 0.1 to 1 MPa.

5. The process according to claim 1 , wherein the photopolymer formulation has a plateau modulus of from 0.1 to 0.6 MPa.

6. The process according to claim 1 , wherein the process further comprises applying a laminating film to the film after drying in step iii).

7. The process according to claim 6 , wherein the film is rolled up together with the laminating film.

8. The process according to claim 1 , wherein the matrix polymers comprise polyurethanes.

9. The process according to claim 1 , wherein the writing monomers comprise acrylates and/or meth(acrylates).

10. The process according to claim 1 , wherein the monofunctional writing monomer has the formula (III)

wherein

R 2 , R 3 , R 4 , R 5 , in each case independently of one another, represent hydrogen or halogen atom or a C1-C6-alkyl, trifluoromethyl, C1-C6-alkylthio, C1-C6-alkylseleno, C1-C6-alkyltelluro or nitro group, with the proviso that at least one substituent of the group R 1 , R 2 , R 3 , R 4 , R 5 is not hydrogen,

R 6 , R 7 , in each case independently of one another, represent hydrogen or a C1-C6-alkyl group and

A represents a saturated or unsaturated or linear or branched C1-C6-alkyl radical or a polyethylene oxide radical or a polypropylene oxide radical having in each case 2-6 repeating units in the polymer chain.

11. The process according to claim 10 , wherein the monofunctional writing monomer has a glass transition temperature T G of <0° C. and a refractive index of >1.50 at 405 nm.

12. The process according to claim 1 , wherein the polyfunctional writing monomer has a refractive index of >1.50 at 405 nm.

13. The process according to claim 1 , wherein the photopolymer formulation comprises urethanes as a plasticizer.

14. The process according to claim 13 , wherein the urethanes are substituted by at least one fluorine atom.

15. The process according to claim 14 , wherein the urethanes have the formula (V)

wherein

n is from 1 to 8 and

R 10 , R 11 , R 12 independently of one another, represent hydrogen or linear, branched, cyclic or heterocyclic organic radicals which are unsubstituted or optionally also substituted by heteroatoms.

16. The process according to claim 1 , wherein the photoinitiator system comprises an anionic, cationic or neutral dye and a coinitiator.

17. The process according to claim 1 , wherein in step ii) plate spacing is set to 250 μm.