Formation of security paper e.g. banknote with colored marking involves providing photosensitive preparation comprising substance which produces colloidal metal particles under UV irradiation effect on a portion of the document

Hoffmann, P.Bret, T.Moreau, V.Hoffman, P.2009-07-202009-07-202009-07-202003https://infoscience.epfl.ch/handle/20.500.14299/41665A process for providing a security paper, in particular a banknote, with a coloured marking, comprising providing a photosensitive preparation on a portion of said document and submitting at least selected areas of said portion to a light beam, wherein said preparation is capable of forming a film on said portion and comprises a substance capable of producing colloidal metal particles under the effect of UV irradiation, and said areas are irradiated by means of an UV-light beam. <IMAGE>[NRG]Formation of security paper e.g. banknote with colored marking involves providing photosensitive preparation comprising substance which produces colloidal metal particles under UV irradiation effect on a portion of the documentpatentCA2533477AU2004261333US7514188DE602004010271DE602004010271EP1654126US2006197333EP1654126AU2004261333CA2533477WO2005011992EP150491733547829