Liquid-crystalline medium for use in a switching element
AssigneeMerck Patent GmbH
InventorsPaul Verbunt, Ties De Jong, Michael Junge, Mila Fischer
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Abstract
Liquid-crystalline media containing one or more mesogenic compounds, one or more chiral compounds, and one or more polymerizable mesogenic compounds, wherein the media exhibit a pitch of 0.55 μm or more and a clearing point of 80° C. or more and wherein the one or more polymerizable mesogenic compounds are contained in an amount, based on the overall contents of the media, of 5% by weight or less, are suitable as modulation materials. Such modulation materials can be used in switching layers and window elements.
Claims21
A window element, which is operable in and electrically switchable between an optically transparent state and a scattering state and which comprises a switching layer containing a material which comprises
- a liquid-crystalline medium comprising one or more mesogenic compounds and one or more chiral compounds, wherein the liquid-crystalline medium has a clearing point of 95° C. or more, and
- a polymeric component comprising one or more polymeric structures obtained by polymerization of one or more polymerizable mesogenic compounds in the liquid-crystalline medium, wherein the polymeric component is contained in the liquid-crystalline material in an amount, based on the overall contents of the material, of 5% by weight or less,
- wherein the polymeric component comprises a polymer network in the liquid-crystalline medium, and
- wherein in the optically transparent state the window element has a haze, determined according to ASTM D 1003, of less than 10%.
A liquid-crystalline medium, comprising
- one or more mesogenic compounds,
- one or more chiral compounds,
- one or more polymerizable mesogenic compounds in an amount, based on the overall contents of the medium, of 5% by weight or less,
- wherein the medium exhibits a pitch of 0.55 μm or more and a clearing point of 95° C. or more, and
- wherein the medium comprises a compound having the formula
A modulation material, comprising
- a liquid-crystalline medium comprising one or more mesogenic compounds and one or more chiral compounds, wherein the liquid-crystalline medium has a clearing point of 95° C. or more and exhibits a pitch of 0.55 μm or more, and
- a polymeric component comprising one or more polymeric structures obtained by or obtainable from polymerization of one or more polymerizable mesogenic compounds, wherein the polymeric component is contained in the material in an amount, based on the overall contents of the material, of 5% by weight or less,
- wherein the polymeric component comprises a polymer network,
- wherein the liquid-crystalline medium exhibits a positive dielectric anisotropy Δε and an optical anisotropy Δn, determined at 20° C. and 589 nm, of 0.13 or more, and
- wherein the one or more chiral compounds contained in the liquid-crystalline medium have an absolute value of the helical twisting power of 5 μm−1 or more.
Dependencies are inferred from the claim text.