Photopolymer formulation having triazine-based writing monomers
View Patent ↗The invention relates to a photopolymer formulation comprising polyurethane matrix polymers, writing monomers, and photoinitiators, wherein the writing monomers comprise compounds of formula (I), where R1, R2, R3 independent of each other are each a halogen atom or an organic radical, wherein at least one of the radicals is an organic radical comprising a radiation hardening group. The invention further relates to the use of the photopolymer formulation for producing holographic media.
1. A photopolymer formulation comprising polyurethane matrix polymers, writing monomers and photoinitiators, wherein the writing monomers comprise compounds of the formula (I)
wherein
R 1 , R 2 , R 3 are each independently OH, halogen or an organic radical, where at least one of the radicals is an organic radical having a radiation-curing group, wherein the organic radical(s) is/are bonded to the triazine ring via an oxygen atom, wherein the photopolymer formulation additionally comprises a urethane as plasticizers, where the urethane is substituted by at least one fluorine atom, and wherein the writing monomer is a colorless liquid and wherein the polyurethane matrix polymers are not substituted by fluorine.
2. The photopolymer formulation of claim 1 , wherein the radiation-curing group is an acrylate or methacrylate group.
3. The photopolymer formulation of claim 1 , wherein R 1 , R 2 , R 3 are each independently halogen and/or substituted or unsubstituted phenoxy, naphthloxy, 2-hydroxyethyl (meth)acrylate radicals, hydroxypropyl (meth)acrylate radicals and/or 4-hydroxybutyl (meth)acrylate radicals, where at least one of the R 1 , R 2 , R 3 radicals is a 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate radical.
4. The photopolymer formulation of claim 3 , wherein at least two of the R 1 , R 2 , R 3 radicals are each independently a 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and/or 4-hydroxybutyl (meth)acrylate radical.
5. The photopolymer formulation of claim 1 , wherein the photoinitiators comprise an anionic, cationic or uncharged dye and a coinitiator.
6. The photopolymer formulation of claim 1 , wherein the urethanes have the general formula (II)
in which n≧1 and n≦8 and R 4 , R 5 , R 6 are each independently hydrogen, linear, branched, cyclic or heterocyclic organic radicals which are unsubstituted or else optionally substituted by heteroatoms, where preferably at least one of the R 4 , R 5 , R 6 radicals is substituted by at least one fluorine atom, and R 4 is more preferably an organic radical with at least one fluorine atom.
7. The photopolymer formulation of claim 1 , wherein the writing monomers additionally comprise a further mono- or polyfunctional writing monomer, which may especially be a mono- or polyfunctional acrylate.
8. A holographic medium prepared from by recording a hologram in the photopolymer formulation of claim 1 .
9. The holographic medium of claim 8 , wherein said hologram is selected from the group consisting of inline holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms, Denisyuk holograms, off-axis reflection holograms, edge-lit holograms, and holographic stereograms.
10. The photopolymer formulation of claim 1 , wherein the polyurethane matrix polymer is obtained by reaction of an isocyanate component a) with an isocyanate-reactive component b), and wherein the isocyanate-reactive component b) is selected from the group consisting of polyester polyols, polyether polyols, polycarbonate polyols, poly(meth)acrylate polyols, polyurethane polyols, and aliphatic, araliphatic or cycloaliphatic di, tri or polyfunctional alcohols containing 2 to 20 carbon atoms.