Method for manufacturing a multilayer data medium with security marking which can be marked by laser

Method for manufacturing a multi-layer data medium by hot rolling under pressure of a stack of a plurality of superimposed layers comprising at least one layer made of at least one thermoplastic material, able to be marked under the effect of laser radiation applied to at least one outer surface (11) of said data medium, wherein:

• at least one layer, named covering layer (21, 22):
• which is transparent to marking laser radiation,
• extending between said outer surface (11) and a layer, named laser marking sub-layer (20), sensitive to this laser radiation, so as to permit the production of a marking in the marking sub-layer (20) under the effect of this laser radiation passing through each covering layer (21, 22),
• incorporating at least one marking (13) with optically variable effect disposed with respect to the laser marking sub-layer so that said outer surface (11) has a portion with optically variable effect optically superimposed on at least one part of the laser marking sub-layer (20) and a portion (16) without marking with optically variable effect optically superimposed on at least one part of the laser marking sub-layer (20),
• wherein:
• said at least one covering layer (21, 22) also incorporates at least one marking agent which is sensitive to said laser radiation so as to permit the production of a marking in said at least one covering layer (21, 22) under the effect of this laser radiation,
• said portion (16) without marking with optically variable effect and said portion with optically variable effect are produced with contents of at least one marking agent which is sensitive to said laser radiation, between said outer surface (11) of the medium and said laser marking sub-layer (20), which are different.

Multi-layer data medium comprising at least one layer made of at least one thermoplastic material, able to be marked under the effect of laser radiation applied to at least one outer surface (11) of this data medium, comprising:

• at least one layer, named covering layer (21, 22):
• which is transparent to marking laser radiation,
• extending between said outer surface (11) and placed covering a layer, named laser marking sub-layer (20), sensitive to this laser radiation, so as to permit the production of a marking in the marking sub-layer (20) under the effect of this laser radiation through each covering layer (21, 22),
• incorporating at least one marking (13) with optically variable effect disposed with respect to the laser marking sub-layer so that said outer surface (11) has a portion with optically variable effect optically superimposed on at least one part of the laser marking sub-layer (20) and a portion (16) without marking with optically variable effect optically superimposed on at least one part of the laser marking sub-layer (20),
• wherein:
• said at least one covering layer (21, 22) also incorporates at least one marking agent which is sensitive to said laser radiation so as to permit the production of a marking in said at least one covering layer (21, 22) under the effect of this laser radiation, said portion (16) without marking with optically variable effect and said portion with optically variable effect have contents of at least one marking agent which is sensitive to said laser radiation, between said outer surface (11) of the medium and said laser marking sub-layer (20), which are different.