Thermochromic liquid crystalline medium
AssigneeMerck Patent GmbH
InventorsDavid Coates, David Bishop, Robert Hammond-Smith
Life of this patent
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Abstract
The invention relates to a thermochromic liquid crystalline medium comprising a liquid crystalline host component and an active component, to a thermochromic ink comprising such a thermochromic liquid crystalline medium encapsulated in a light transmissive polymeric material, to the use of a thermochromic medium or ink in decorative applications like pigments, inks and paints, cosmetics, thermodiagnostic applications like medical thermography, thermometry, optical and electrooptical applications, and security applications and devices, to a security marking or device comprising a thermochromic liquid crystalline medium or thermochromic ink and to a document of value comprising such a security marking.
Claims22
A thermochromic liquid crystalline medium comprising a liquid crystalline host mixture and an optically active component, wherein the liquid crystalline host mixture has a smectic—nematic phase transition temperature in the range from 0 to 60° C and the optically active component comprises at least one chiral dopant with a helical twisting power (HTP) of at least 20 μm−1.
Dependencies are inferred from the claim text.