Holographic media and photopolymers

1. A photopolymer composition comprising

a) an unsaturated glycidyl ether acrylate urethane of formula (1a), formula (1b), or mixtures thereof

wherein

n is an integer from 2 to 6;

R1 is a mono- or polynuclear organic radical comprising an aromatic group and from 4 to 36 carbon atoms;

R2 is an olefinically unsaturated radical comprising from 3 to 30 carbon atoms; and

R is an organic radical derived from an aliphatic or aromatic di- or polyisocyanate and comprises from 2 to 30 carbon atoms;

b) a binder system;

c) a photoinitiator system; and

d) optionally, a free radical stabilizer, a catalyst, and/or one or more further additives.

2. The photopolymer composition of claim 1 , wherein

R1 is oxyphenyl, oxybromophenyl, oxydibromophenyl, or oxynaphthyl;

R2 is derived from an acid R2-COOH, wherein R2-COOH is selected from the group consisting of acrylic acid, methacrylic acid, 3-acrylyloxypropionic acid, or an adduct of hydroxyethyl and hydroxybutyl acrylate with maleic anhydride; and

R is derived from an n-functional isocyanate R(NCO) n , wherein R(NCO) n , is selected from the group consisting of 2,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, isocyanatomethyl-1,8-octane diisocyanate, tris(p-isocyanatophenyl) thiophosphates, tris(4,4′- and/or 2,4′-) diisocyanatodicyclohexylmethane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane, diisocyanatodicyclohexylmethane 2,4- and/or 2,6-toluidene diisocyanate, and trimers of hexamethylene diisocyanate having an isocyanurate and/or iminooxadiazinetrione structure.

3. The photopolymer composition of claim 1 , wherein said unsaturated glycidyl ether acrylate urethane of a) has a refractive index at 405 nm of greater than 1.53.

4. The photopolymer composition of claim 1 , wherein said crosslinked binder is a two-component polyurethane system.

5. The photopolymer composition of claim 4 , wherein said two-component polyurethane system comprises, as the isocyanate component, oligo- and polyisocyanates of aliphatic diisocyanates comprising an isocyanurate, allophanate, biuret, uretdione, or iminooxadiazinedione structure, and the polyol component comprises polyethylene/polypropylene glycols having a polypropylene content of at least 70% and a functionality of from 1.9 to 2.5 and/or polyester-polyether-polyester block polyols based on polytetrahydrofurans having a number average molecular weight of from 400 to 1400 g/mol and s-caprolactone, wherein said polyester-polyether-polyester block polyols have a number average molecular weight of from 1500 to 4000 g/mol.

6. A process for producing a medium for recording visual holograms, comprising applying the photopolymer composition of claim 1 to a substrate or in a mould and curing said photopolymer composition.

7. The medium for recording visual holograms produced by the process of claim 6 .

8. An optical element or image comprising the medium of claim 7 .

9. A glycidyl ether acrylate urethane of formula (1a) or (1b)

wherein

n is an integer from 2 to 6;

R1 is a halogen- and/or alkylthio-, and/or arylthio-substituted oxyphenyl ring or is a halogen-, alkyl-, aryl-, alkylthio-, or arylthio-substituted oxynaphthyl, oxyanthracenyl, oxyphenantryl, N-carbazolyl, N-alkylcarbazolzyl, N-phthalimidyl, N-phenothiazinyl, N-alkylphenothiazinyl, or oxytriarylmethyl radical,

R2 is an olefinically unsaturated radical comprising from 2 to 30 carbon atoms;

R is an organic radical derived from an aliphatic or aromatic di- or polyisocyanate and comprising from 2 to 30 carbon atoms.