Method for manufacturing a multilayer data medium with reflecting metallised inscriptions

Method of manufacturing a multilayer data medium by hot rolling under pressure of a stack of a plurality of superimposed layers comprising at least one layer of at least one thermoplastic material, said multilayer data medium having inscriptions, named reflecting metallised inscriptions, having a metallic appearance, being at least partially reflective and visible from at least one outer surface of said multilayer data medium, said hot rolling being effected in a temperature range, named rolling temperature range, wherein:

• one surface, named impression surface, of at least one transparent layer, named impression layer, of said stack is imprinted thereon with a varnish composition in a pattern, named the basic pattern, selected to be able to receive said reflecting metallised inscriptions, said varnish composition being selected in order—after curing—to be transparent and to have:
• a surface tension of more than 40 dynes/cm and a smooth surface condition with specular reflection of more than 50% measured according to the ISO 2813 standard at an angle of 60°,
• no glass-transition temperature in the rolling temperature range,
• said reflecting metallised inscriptions are imprinted in contact with said basic pattern of said impression layer with a composition of metallised ink comprising a curable binder incorporating discrete particles, named the reflecting metallised particles, in the general form of platelets dispersed in the curable binder having a grain size selected to form pigments having a metallic, at least partially reflecting, appearance,
• then said stack is formed, comprising said impression layer, said impression surface being opposite to said outer surface and having said reflecting metallised inscriptions applied thereto in contact with another adjacent layer of the stack,
• then this stack is hot rolled under pressure.