Colour laser marking methods of security document precursors

摘要

A method of color laser marking a security document precursor including, in order, at least: a) a polymeric foil; b) at least one colorless color forming layer for generating a color different from black containing at least an infrared absorber, a color forming compound and a polymeric binder; and c) either a lasermarkable polymeric support or a lasermarkable layer for generating a black color; comprising the steps of: (1) laser marking a color different from black in the colorless color forming layer with an infrared laser used in continuous wave mode; and (2) laser marking a black color by carbonization in the lasermarkable polymeric support or the lasermarkable layer with the same infrared laser used in a pulsed mode; and wherein at least one of the polymeric foil and the lasermarkable polymeric support is transparent for the infrared light of the infrared laser.

主权项

1. A method of colour laser marking a security document precursor including, in order, at least:
a) a transparent polymeric foil; b) at least one colourless colour forming layer for generating a colour different from black containing at least an infrared absorber, a colour forming compound and a polymeric binder; and c) either a lasermarkable polymeric support or a lasermarkable layer for generating a black colour;comprising the steps of:(1) laser marking a colour different from black in the colourless colour forming layer with an infrared laser used in continuous wave mode; and(2) laser marking a black colour by carbonization in the lasermarkable polymeric support or the lasermarkable layer with the same infrared laser used in a pulsed mode; andwherein at least one of the transparent polymeric foil and the lasermarkable polymeric support is transparent for the infrared light of the infrared laser.