Method for impressing directly on paper holograms, kinetic holograms, diffraction patterns or microengravings producing other optical effects

摘要

A method for impression microengravings, which reproduce holograms, kinetic holograms, or diffraction patterns, directly on paper through an embossing process. Paper is subjected to a humidification step to give it a degree of humidity between 60 and 80% of relative humidity. The humidified paper is then passed through an embossing group, consisting of an embossing cylinder carrying the microengravings and a counterthrust cylinder, at a temperature and a pressure on the paper within the ranges of 90-220 C. and 20-120 kg/mm.sup.2, respectively.