Hot embossing of micrographic elements in polypropylene

Micrographic features generated by electron beam lithography have been hot embossed in biaxially-oriented polypropylene (BOPP). Each micrographic element consisted of a sub-field of 30 × 30 μm with a specific configuration of symbols, lettering and graphics. The micrographic elements were integrated with arrays of diffractive gratings in the form of an optically variable device. A high quality embossing of various micrographic elements has been demonstrated in features with a linewidth dimension ⩾365 nm and depth ⩾255 nm. The replication of arrays of micrographic elements was achieved uniformly over an area of 20 × 20 mm in the BOPP film by embossing at a temperature of 130 °C.