| 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 panicles in a film or a coaling layer of an elastic polymer. In a particular embodiment, the panicles arc optically variable pigment flakes, oriented in a position which is substantially different from an alignment in the plane of the film or coating layer. |
