Colour laser marking methods of security document precursors

Abstract

A method of color laser marking a security document precursor including at least: a transparent biaxially stretched polyethylene terephthalate foil; 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 a laser markable polymeric support or a laser markable layer for generating a black color; comprising the steps of: laser marking the colorless color forming layer through the transparent polymeric foil with a infrared laser used in continuous wave mode to generate a color different from black; and laser marking the laser markable polymeric support or the laser markable layer through the transparent polymeric foil with the same infrared laser but used in a pulsed mode to generate a black color.

Dependencies are inferred from the claim text.