IMPROVEMENTS IN SECURITY SHEETS COMPRISING SECURITY ELEMENTS

The present invention relates to a method of manufacturing a security sheet. The security sheet comprises a plastic substrate (40) extending between first and second outer surfaces (41, 42). A security element (11) extends through the plastic substrate and comprising at least one first region (17) at a first distance (D1) from the first outer surface and at least one second region at a second distance (D2) from the first outer surface. The first and second distances are different. The method comprises forming a core structure (10) having the security element therein by firstly forming at least one core layer (12) with at least one perforation (20) therein and subsequently inserting the security element into the at least one perforation.