ROTOGRAVURE PRINTING PROCESSES FOR PRODUCING OPTICALLY VARIABLE SECURITY FEATURES

摘要

The present invention is related to the filed of optically variable security elements comprising a region based on a single cured ink comprising a cholesteric liquid crystal polymer, said region having at least two, preferably at least three, patterns exhibiting, at at least one viewing angle, a different CIE (1976) color index parameter and/or a different position of the selective reflection band for protecting security documents against counterfeiting and/or illegal reproduction. In particular, the present invention relates to processes for manufacturing said features, when the processes comprises the steps of a) applying on a substrate by a rotogravure process with the use of a gravure cylinder having at least two, preferably at least three, different engravings a single cholesteric liquid crystal precursor composition, b) heating the applied composition to bring said composition to a cholesteric liquid crystal state, and c) curing the composition so as to form the region based on a single cured ink comprising a cholesteric liquid crystal polymer.

主权项

1. A process for manufacturing an optically variable security feature comprising a region based on a single cured ink comprising a cholesteric liquid crystal polymer, said region having at least two, preferably at least three, patterns exhibiting, at at least one viewing angle, a different CIE (1976) color index parameter and/or a different position of the selective reflection band, said process comprising the steps of:
a. applying on a substrate, by a rotogravure process with the use of a gravure cylinder having at least two, preferably at least three, different engravings, a single cholesteric liquid crystal precursor composition, b. heating the applied composition to bring said composition to a cholesteric liquid crystal state, and c. curing the composition so as to form the region based on a single cured ink comprising a cholesteric liquid crystal polymer.