Radiation-crosslinking and thermally crosslinking PU systems based on isocyanate-reactive block copolymers
View Patent ↗The present invention provides polyurethane systems which cure by radiation and thermal action with crosslinking, and use thereof for the production of holographic media. The polyurethane compositions of the invention comprise A) polyisocyanates, B) isocyanate-reactive block copolymers, C) compounds having groups which react on exposure to actinic radiation with ethylenically unsaturated compounds with polymerization, D) optionally free radical stabilizers and E) photoinitiators.
1. A polyurethane system comprising
A) one or more oligomers of aliphatic and/or cycloaliphatic di- or triisocyanates,
B) one or more isocyanate-reactive block copolymers,
C) one or more compounds selected from the group consisting of α,β-unsaturated carboxylic acid derivatives, vinyl ethers, propylene ether, allyl ether, compounds containing cyclopentadienyl units, olefinically unsaturated compounds, epoxy acrylates and vinyl aromatics,
D) optionally one or more free radical stabilizers, and
E) one or more photoinitiators.
2. The polyurethane system of claim 1 , wherein said one or more isocyanate-reactive block copolymers comprise polyester, polyether, polycarbonate, poly(meth)acrylate, and/or polyurethane segments arranged blockwise.
3. The polyurethane system of claim 1 , wherein said one or more isocyanate-reactive block copolymers are based on polycarbonate-, polyether- or polyester-based dihydroxyfunctional compounds as the internal block, the hydroxyl groups of which are subjected to a blockwise addition reaction with lactones to give three- or multi-block copolymers.
4. The polyurethane system of claim 3 , wherein said dihydroxyfunctional compounds are based on polyether diols which are based on ethylene oxide, propylene oxide, and/or tetrahydrofuran.
5. The polyurethane system of claim 3 , wherein said lactones are selected from the group consisting of butyrolactone, ε-caprolactone, methyl-ε-caprolactone, γ-phenyl-ε-caprolactone, ε-decanolactone, and mixtures thereof.
6. The polyurethane system of claim 3 , wherein said one or more isocyanate-reactive block copolymers are based on polyether-based dihydroxyfunctional compounds as the internal block, wherein said internal polyether block has a number average molar mass in the range of from 250 g/mol to 2000 g/mol.
7. The polyurethane system of claim 3 , wherein the lactone blocks are based on ε-caprolactone and each have a number average molar mass in the range of from 114 g/mol to 700 g/mol.
8. The polyurethane system of claim 1 , wherein said one or more isocyanate-reactive block copolymers comprise linear poly (ε-caprolactone)-block-poly(tetrahydrofuran)-block-poly(ε-caprolactone)polyols having terminal hydroxyl groups and a number average molar mass of from 500 g/mol to 5000 g/mol, wherein the average mass fraction of the poly(tetrahydrofuran) block, based on the number average block copolymer, is in the range of from 0.2 to 0.9 and the average mass fraction of the two poly(ε-caprolactone) blocks, based on the number average block copolymer, is in the range of from 0.1 to 0.8.
9. The polyurethane system of claim 1 , wherein the molar ratio of the NCO to the OH groups of the components of said system is in the range of from 0.90 to 1.25.
10. The polyurethane system of claim 1 , wherein said one or more compounds of component C) are selected from the group consisting of 9-vinylcarbazole, vinylnaphthalene, bisphenol A diacrylate, tetrabromobisphenol A diacrylate, 1,4-bis(2-thionaphthyl)-2-butyl acrylate, pentabromophenyl acrylate, naphthyl acrylate, and propane-2,2-diylbis[(2,6-dibromo-4,1-phenylene)oxy(2-{[3,3,3-tris(4-chlorophenyl)propanoyl]oxy}propane-3,1-diyl)oxyethane-2,1-diyl]diacrylate.
11. A polymeric plastic prepared from the polyurethane system of claim 1 .
12. The polymeric plastic of claim 11 , wherein said polymeric plastic is a layer or a molding.
13. The polymeric plastic of claim 11 , wherein said polymeric plastic has a glass transition temperature of less than −40° C.
14. A holographic media prepared from the polyurethane system of claim 1 .
15. A holographic media comprising at least one polymeric plastic of claim 11 .
16. A polyurethane system comprising
A) one or more polyisocyanates,
B) one or more isocyanate-reactive block copolymers,
C) one or more compounds selected from the group consisting of α,β-unsaturated carboxylic acid derivatives, vinyl ethers, propylene ether, allyl ether, compounds containing cyclopentadienyl units, olefinically unsaturated compounds, epoxy acrylates and vinyl aromatics,
D) optionally one or more free radical stabilizers, and
E) one or more photoinitiators
wherein said one or more isocyanate-reactive block copolymers comprise linear poly (ε-caprolactone)-block-poly(tetrahydrofuran)-block-poly(ε-caprolactone)polyols having terminal hydroxyl groups and a number average molar mass of from 500 g/mol to 5000 g/mol, wherein the average mass fraction of the poly(tetrahydrofuran) block, based on the number average block copolymer, is in the range of from 0.2 to 0.9 and the average mass fraction of the two poly(ε-caprolactone) blocks, based on the number average block copolymer, is in the range of from 0.1 to 0.8.
17. A polymeric plastic prepared from the polyurethane system of claim 16 .
18. The polymeric plastic of claim 17 , wherein said polymeric plastic is a layer or a molding.
19. A holographic media prepared from the polyurethane system of claim 16 .
20. A holographic media comprising at least one polymeric plastic of claim 17 .