| 摘要 |
The invention is concerned with security elements for security articles such as banknotes, cheques and the like.The invention further comprises a security element for use with security materials, said element comprising a first layer, to one side of which is applied at least one optically variable device, and on the other side of said first layer are applied indicia, and a thermochromic coating applied over the indicia, wherein the thermochromic coating comprises a thermochromic material which is coloured when the temperature of said thermochromic coating is below an activation temperature, which colour substantially obscures the indicia and enhances the visibility of the optically variable device, and wherein the thermochromic material becomes colourless at or above said activation temperature, to thereby reveal the indicia, and to render the optically variable device substantially invisible in reflected light. |
