METHOD FOR MAKING SECURE VALUABLE DOCUMENTS

摘要

The invention concerns a method for making secure valuable documents, comprising steps which consists in: incorporating in each document, upon its production, at least one active substance irreversibly changing colour under the effect of an external microwave radiation, said colour change rendering said documents useless and legally identifiable. The invention is characterized in that the external microwave radiation induces an irreversible chemical modification of the active substance by creating an extended p-conjugated system. The invention also concerns a valuable document comprising at least one active substance shifting into an extended p-conjugated system under the effect of an external microwave radiation.