1. US6391824 - Process for the preparation of coated continuous sheets to be printed by impact-free heat printers, and sheet thus obtained

A non-impact, thermal transfer printing sheet having a base sheet of fibrous paper or synthetic with or without a security device, coated with a composition comprising (1) lactone, spiropyrane coloration, or an iron metallic complexes that reacts with weak an organic acid to produce coloration when the sheet is heated via a thermal head, (2) an activator to accelerate the reaction, (3) absorbent materials to absorb the resulting products of the reaction, and (4) an inorganic phosphorescent ZnS:Cu pigment having a particle size sufficient to produce phosphorescence in a predetermined time and wave-length and a process of making thereof are disclosed. The sheet is capable of being printed using a thermal transfer printing head and providing phosphorescence when activated by ultraviolet light containing wavelengths of between 440 and 640 nm.