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Published online by Cambridge University Press: 01 February 2011
The hot embossing of grating-based optically variable devices has been demonstrated in biaxially-oriented polypropylene (BOPP). The embossing of several types of optically variable device has been examined including portrait, non-portrait and 3 dimensional images. The images embossed into BOPP have displayed a novel optically variable effect when viewed in transmitted light. Embossing of the grating structures was examined over a range of temperatures (80-155 °C) at 135 kN force. High quality replication was achieved over a full embossing area of 80 x 80 mm at temperatures > 120 °C.