Hot foil transfer: a novel approach

摘要

The current use of optically variable devices (OVDs) is based on the well-known technology of hot-foil stamping that allows security features to be transferred to documents. Different types of OVDs such as holograms, kinegrams, pixelgrams or blazed gratings can be applied by this way. In spite of progress in creation computer-driven hot-foil transfer machines based on dot-matrix thermoprinting, the most typical technique utilizes presses with special stamps. A novel approach to hot-foil transfer involves the application of foil without temperature sensitive adhesive. Such an adhesive is distributed imagewise directly on the embossed hot-foil surface. A simple flat stamp or a laminator can be used for the application of different foil images. The said method gives more flexibility to customers in creating their own security features. The features may contain variable information: numbers, text, pictures and drawings of any kind. One of the main problem of traditional hot-foil transfer is the restricted resolution that strongly depends from stamp quality. The described process simply needs a flat stamp and its resolution mainly depends from initial adhesive distribution. The currently achieved resolving power is about 250 dpi and this figure can be further improved.