Patent ID: 8921012

Claim:
A process for the production of exposed, holographic media comprising a photopolymer formulation having a modulus G UV of between 0.1 to 160 MPa and a Δn≧0.008, wherein the process comprises: i) providing a photopolymer formulation comprising: A) matrix polymers as an amorphous network, B) a combination of a monofunctional writing monomer and a polyfunctional writing monomer, C) a photoinitiator system, D) optionally a non-photopolymerisable component, and E) optionally catalysts, free radical stabilisers, solvents, additives and other auxiliaries and/or additives is provided; ii) forming a media which comprises the photopolymer formulation; iii) subjecting the media to a holographic exposure procedure in order to record the hologram; and iv) exposing the medium as a whole to UV radiation for at least 15 min in order to fix the hologram, and wherein, while exposing the medium to UV, the modulus G UV of the exposed photopolymer formulation is determined by measuring the curing of the matrix in an oscillation rheometer as follows: oscillation measuring mode at a constant angular frequency ω 0 of 62.8 rad/s and a controlled logarithmic deformation amplitude ramp deformation amplitude of 0.01%-0.001% temperature 50° C., normal force regulation set at 0 Newton recording of the storage modulus G′ during the UV exposure over the measuring time for at least 15 minutes or until a constant value of G′ was reached; this value is taken as G UV , wherein the writing monomers comprise acrylate- and/or methacrylate-functionalised compounds, wherein the total content of writing monomers in the photopolymer formulation is from 30% to 45% by weight, wherein the unexposed photopolymer formulation has a modulus G 0 of <0.7 MPa, wherein the modulus G 0 is determined by measuring the curing of the matrix in an oscillation rheometer as follows: plate spacing 250 μm, plate diameter 12 mm oscillation measuring mode at a constant angular frequency ω 0 of 62.8 rad/s and a controlled logarithmic deformation amplitude ramp of 10%-0.01% temperature 50° C., normal force regulation set at 0 Newton recording of the storage modulus G′ over the measuring time for at least 2 hours or until a constant value of G′ was reached; this value is referred to as G 0 , and the modulus G UV of the exposed photopolymer formulation is adjusted in the intended range of between 0.1 and 160 MPa via the ratio of the relative proportion of the monofunctional writing monomer to the relative proportion of the polyfunctional writing monomer, based on the total writing monomer content, in such a way that a high modulus is realised by a high relative proportion of the polyfunctional writing monomer and a low modulus by a high relative proportion of the monofunctional writing monomer, based on the total writing monomer content, and wherein the Δn of individual exposed, holographic media having different proportions of monofunctional and polyfunctional writing monomers varies by less than 55%, the variation being calculated as follows: (Δn max −Δn min )/Δn min ·100%.