Method for the propagation of cholesteric reflective bands of photopolymerised cholesteric liquid crystals and optical elements produced by this method

摘要

A process for the broadening of cholesteric reflection bands of photopolymerisable cholesteric liquid crystals (I) comprises (1) partial polymerisation of a layer containing (I) by illumination for a short defined duration at a defined temperature; (2) stopping for a defined time without illumination (dark phase) at a defined temperature; and (3) fixing of the resulting layer by illumination with actinic light at a defined temperature. Also claimed are (i) a process for the production of a photostructured cholesteric filter and reflector with broadened reflection bands of (I), by carrying out steps (1)-(3) through a mask followed by replacement of the mask by a second mask and repeating steps (1)-(3) with a change in at least one of the parameters in steps (1) or (2) such that a non-illuminated part of the material is irradiated; (ii) the photopolymerisable cholesteric liquid crystal (I) having reflection bands broadened by at least 10 nm in comparison with a conventionally prepared cholesteric liquid crystal; (iii) an optical element containing at least a layer of (I); and (iv) a device containing the optical element.