PIEZOCHROMIC SECURITY ELEMENT

摘要

The invention discloses a reversibly piezochromic security element for the forgery-protection of value documents, the security element being characterized in that it comprises a collection of optically contrasting pigment particles in a film or a coating layer of an elastic polymer. In a particular embodiment, the particles are optically variable pigment flakes, oriented in a position which is substantially different from an alignment in the plane of the film or coating layer.