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US 10,329,244 B2Granted
Moisture-stable holographic media
AssigneeCovestro Deutschland AG
InventorsThomas Fäcke, Friedrich-Karl Bruder, Thomas Rölle, Dennis Hönel
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Abstract
The invention relates to novel compounds which are especially suitable for use as writing monomers in holographic media. The invention further provides a photopolymer and a holographic medium comprising the inventive compounds, and an optical display, a security document and a holographic optical element comprising an inventive holographic medium.
Claims13
A photopolymer comprising matrix polymers, writing monomers and photoinitiators, wherein the writing monomers comprise compound of formula (I)
- in which
- R1 is an aliphatic hydrocarbyl radical having 1-8 carbon atoms;
- R2 is hydrogen or methyl;
- Ar is an aromatic radical of the formula (II)
- in which
- R3 are independently radicals selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl, branched or unbranched alkyl, branched or unbranched alkylthiyl, halogen, where at least one of the R3 radicals is a radical selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl;
- n=1 to 5;
- or Ar is an aromatic radical of the formula (III)
- in which
- R3 are independently radicals selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl, branched or unbranched alkyl, branched or unbranched alkylthiyl, halogen, where at least one of the R3 radicals is a radical selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl;
- o=1 to 3;
- p=1 to 4,
- wherein the compound of the formula (I) has only one radiation-curing group, and wherein a reflection hologram comprising the photopolymer has a refractive index modulation of Δn>0.025 and value of ΔTmin(1) of <2 nm and a value ΔTmin(2) of <5 nm, wherein ΔTmin(1) is determined by first obtaining Tmin(1), the resonance frequency (in nm) in the transmission spectrum at the lowest transmission from a sample stored at 100° C. in an oven for two days and cooled within 2 minutes, subsequently obtaining Tmin(2) from a sample stored at about 20° C. and 40%-50% relative humidity for 7 days, and taking the difference in the peak wavelengths of the two measurements Tmin(1) and Tmin(2), and wherein ΔTmin(2) is determined by first obtaining Tmin(3) the resonance frequency (in nm) in the transmission spectrum at the lowest transmission from a sample stored at 60° C./95% relative air humidity for two days and cooled within 2 minutes, subsequently obtaining Tmin(4) from a sample stored at about 20° C. and 40%-50% relative humidity for 7 days, and taking the difference in the peak wavelengths of the two measurements Tmin(3) and Tmin(4).
10 more elements
A photopolymer comprising matrix polymers, writing monomers, monomeric fluorourethanes, and photoinitiators, wherein the writing monomers comprise compound of formula (I)
- in which
- R1 is an aliphatic hydrocarbyl radical having 1-8 carbon atoms;
- R2 is hydrogen or methyl;
- Ar is an aromatic radical of the formula (II)
- in which
- R3 are independently radicals selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl, branched or unbranched alkyl, branched or unbranched alkylthiyl, halogen, where at least one of the R3 radicals is a radical selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl;
- n=1 to 5;
- or Ar is an aromatic radical of the formula (III)
- in which
- R3 are independently radicals selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl, branched or unbranched alkyl, branched or unbranched alkylthiyl, halogen, where at least one of the R3 radicals is a radical selected from the group of substituted or unsubstituted phenyl, substituted or unsubstituted phenylthiyl;
- o=1 to 3;
- p=1 to 4,
- wherein the compound of the formula (I) has only one radiation-curing group and wherein a hologram comprising the photopolymer has a refractive index modulation of Δn>0.025 and value of ΔTmin(1) of <2 nm and a value ΔTmin(2) of <5 nm, wherein ΔTmin(1) is determined by first obtaining Tmin(1), the resonance frequency (in nm) in the transmission spectrum at the lowest transmission from a sample stored at 100° C. in an oven for two days and cooled within 2 minutes, subsequently obtaining Tmin(2) from a sample stored at about 20° C. and 40%-50% relative humidity for 7 days, and taking the difference in the peak wavelengths of the two measurements Tmin(1) and Tmin(2), and wherein ΔTmin(2) is determined by first obtaining Tmin(3) the resonance frequency (in nm) in the transmission spectrum at the lowest transmission from a sample stored at 60° C./95% relative air humidity for two days and cooled within 2 minutes, subsequently obtaining Tmin(4) from a sample stored at about 20° C. and 40%-50% relative humidity for 7 days, and taking the difference in the peak wavelengths of the two measurements Tmin(3) and Tmin(4).
10 more elements
Dependencies are inferred from the claim text.