Rewritable heat-sensitive coloured image storage medium useful in e.g. label or magnetic card

摘要

Rewritable, heat-sensitive coloured image storage medium has a heat-sensitive layer of cholesteric liquid crystal compound (I) with a molecular weight /} 2000 and Tg >= 35 deg C, between a pair of opposite substrate plates, at least one of which is transparent. Also claimed is a method of storing a coloured image in a medium of this type. A coloured image is stored in the material by selectively changing the temperature of the layer from one value to another to form an image and giving the image by cooling the medium rapidly to a temperature below Tg, preferably at a rate >= 1 deg C/minute. The material preferably is heated with a laser ray, thermal head, hot roller or hot stamp or cooled with a cold roller or cold stamp.