Photopolymer compositions as printable formulations

1. A polyurethane composition suitable for printing comprising

A) a polyisocyanate component, which comprises an NCO-terminated polyurethane prepolymer, wherein said NCO-terminated polyurethane prepolymer comprises NCO groups that are primarily aliphatically bonded and wherein said NCO-terminated polyurethane prepolymer is based on a hydroxy-functional compound having an OH functionality in the range of from 1.6 to 2.05;

B) an isocyanate-reactive polyetherpolyol;

C) a urethane acrylate and/or urethane methacrylate having at least one aromatic structural unit and a refractive index of greater than 1.50 at 405 nm, wherein said urethane acrylate and/or urethane methacrylate is free of NCO groups and OH groups;

D) a free radical stabilizer;

E) a photoinitiator comprising a borate salt and one or more dyes having absorption bands which at least partly cover the spectral range of from 400 to 800 nm;

F) optionally a catalyst; and

G) one or more auxiliaries and/or additives comprising a polyester-modified polydimethylsiloxane, a fluorine-modified polymer, a foam-destroying polysiloxane, a hydrophobic solid, a hydrophobic emulsifier, a polyether-modified polymethylalkylsiloxane, a non-ionic polyacrylate copolymer, or mixtures thereof.

2. The polyurethane composition of claim 1 , wherein the prepolymer in A) comprises a urethane or allophanate of an aliphatic isocyanate-functional compound and an oligomeric or polymeric isocyanate-reactive compound, and wherein the prepolymer has a number average molar mass of from 200 to 10,000 g/mol and an NCO functionality of from 1.9 to 5.0.

3. The polyurethane composition of claim 1 , wherein the isocyanate-reactive polyether polyol B) comprises a difunctional polyetherpolyol based on propylene oxide and ethylene oxide and has a proportion of less than 10% by weight, based on the total mass of the polyether polyol, of repeating units derived from ethylene oxide and a number average molar mass of from 2000 to 4200 g/mol.

4. The polyurethane composition of claim 1 , wherein the urethane acrylate C) comprises an adduct of an aromatic triisocyanate or a trimer of an aromatic diisocyanate with hydroxyethyl acrylate, hydroxypropyl acrylate, or 4-hydroxybutyl acrylate.

5. The polyurethane composition of claim 1 comprising

A) from 15 to 30% by weight of the polyisocyanate component;

B) from 30 to 56.96% by weight of the isocyanate-reactive polyetherpolyol;

C) from 20 to 35% by weight of the urethane acrylate and/or urethane methacrylate;

D) from 0.01 to 0.5% by weight of the free radical stabilizer;

E) from 1 to 3% by weight of the photoinitiator, of which is from 0.01 to 0.2% by weight of each of the blue-sensitive dye, the green sensitive dye, and the red sensitive dye;

F) from 0 to 1% by weight of the catalyst; and

G) from 7 to 20% by weight of the one or more auxiliaries and/or additives.

6. A process for printing on a substrate comprising printing a printing ink comprising the polyurethane composition of claim 1 to a support layer thereby forming a photopolymer layer on the support layer.

7. The process of claim 6 , wherein the support layer is based on a compound selected from the group consisting of polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, cellulose acetate, cellulose hydrate, cellulose nitrate, a cycloolefin polymer, polystyrene, a polyepoxide, polysulfone, cellulose triacetate, polyamide, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, polydicyclopentadiene, and mixtures thereof.

8. The process of claim 6 , wherein the support layer is in the form of a film laminate or coextrudate.

9. The process of claim 6 , wherein the photopolymer layer has a total layer thickness of from 3 to 100 μm.

10. The process of claim 6 , further comprising applying a covering layer to the photopolymer layer after the photopolymer layer is printed on the support layer.

11. The process of claim 6 , wherein the covering layer is based on the same material as the support layer.

12. A printed article obtained by the process of claim 6 .

13. A process for recording a visual hologram comprising exposing the printed article of claim 12 .

14. An optical element, image, or display comprising the printed article of claim 12 .

15. A media or holographic film obtained by the process of claim 13 .

16. The polyurethane composition of claim 1 , wherein the prepolymer in A) comprises a urethane or allophanate of an aliphatic isocyanate-functional compound and an oligomeric or polymeric isocyanate-reactive compound, and wherein the prepolymer has a number average molar mass of from 200 to 10,000 g/mol and an NCO functionality of from 1.9 to 5.0, wherein the isocyanate-reactive polyether polyol B) comprises a difunctional polyetherpolyol based on propylene oxide and ethylene oxide and has a proportion of less than 10% by weight, based on the total mass of the polyether polyol, of repeating units derived from ethylene oxide and a number average molar mass of from 2000 to 4200 g/mol, and wherein the urethane acrylate C) comprises an adduct of an aromatic triisocyanate or a trimer of an aromatic diisocyanate with hydroxyethyl acrylate, hydroxypropyl acrylate, or 4-hydroxybutyl acrylate.