SECURITY DEVICE USING LIQUID CRYSTALS

摘要

The invention generally relates to optically variable devices, methods of preparation and applications or uses therefor. In particular, the invention includes trigger molecules employed as a dopant for a liquid crystal material. The liquid crystal material contains helical elements having a natural twist. The dopant is effective to change the natural twist of the helical elements when the dopant is addressed with incident light. Suitable dopants are selected from binaphthalene and derivatives thereof.

主权项

1. A dopant for a liquid crystal material which contains helical elements having a natural twist, the dopant effective to change the natural twist of the helical elements when addressed with incident light, the dopant comprising at least one trigger molecule having a structure selected from the group consisting of Formulas A, A1, A2, A3, 1, 2, 3 and mixtures thereof: wherein each of R1, R2 and R3 is independently H, aryl or alkyl, linked directly or as ethers or esters, to confer solubility and modulate twisting power, each of X and Y is independently O, O(CH2)3 O—, O(CH2)4 O— or O(CH2)6 O—, and P is acrylate, methacrylate or styrene.