Selection method for additives in photopolymers
The invention relates to a method for selecting compounds which can be used as additives in photopolymer formulations for producing light holographic media, and to photopolymer formulations which contain at least one softener which are selected according to the claimed method. The invention also relates to the use of photopolymer formulations for producing holographic media.
1. A method for preparing a photopolymer formulation comprising providing at least one plasticizer, wherein the at least one plasticizer has a volatility TGA95 of >100° C. and a refractive index n D 20 of ≤1.4600, and wherein the at least one plasticizer comprises urethanes of 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, wherein at least one of the radicals R 1 , R 2 , R 3 is substituted by at least one fluorine atom,
providing a matrix polymer, a writing monomers and a photoinitiator, and preparing the photopolymer formulation by incorporating the at least one plasticizer into the photopolymer formulation.
2. The method according to claim 1 , wherein the plasticizer has a volatility TGA95 of >120° C. and the refractive index thereof nD is ≤1.4300.
3. A photopolymer formulation comprising matrix polymers, writing monomers and photoinitiators, wherein the photopolymer formulation is prepared by the method according to claim 1 and wherein the matrix polymers comprise polyurethanes and wherein the at least one plasticizer comprises urethanes of 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, wherein at least one of the radicals R 1 , R 2 , R 3 is substituted by at least one fluorine atom, urethanes, and wherein the urethane is optionally substituted by at least one fluorine atom.
4. The photopolymer formulation according to claim 3 , wherein the photoinitiators comprise an anionic, cationic or neutral dye and a coinitiator.
5. The photopolymer formulation according to claim 3 , wherein R1 represents an organic radical having at least one fluorine atom.
6. The photopolymer formulation according to claim 3 , wherein the writing monomers comprise a monofunctional acrylate of the formula (IV)
wherein
R 7 , R 8 , independently of one another, represent hydrogen or linear, branched, cyclic or heterocyclic organic radicals which are unsubstituted or optionally also substituted by heteroatoms.
7. The photopolymer formulation according to claim 3 , wherein the writing monomers comprise a polyfunctional writing monomer.
8. The photopolymer formulation according to claim 3 , wherein, the writing monomers comprise a polyfunctional acrylate.