Process for protecting a document, protective device comprising an adhesive layer and document

A protective device for a document having variable inscriptions to be protected, said protective device comprising:

• at least one transparent film bearing at least one adhesive layer comprising at least one thermoplastic polymer,
• wherein said thermoplastic polymer is chosen from the group made up of thermoplastic polymers having a hydroxyl number, measured according to the standard DIN 53 240/2, of between 3 mg of KOH/g and 60 mg of KOH/g, thermoplastic polymers having an acid number, measured according to the standard DIN EN ISO 2114, of between 2 mg of KOH/g and 150 mg of KOH/g, copolymers thereof and blends thereof,
• wherein said thermoplastic polymer has a glass transition temperature, measured by differential scanning calorimetry, between 40° C. and 110° C., and
• wherein adhesive layer also comprises at least one crosslinking agent, each crosslinking agent chosen from the group of aliphatic compounds comprising between 4 and 50 carbon atoms, having on average at least 2.8 functions, chosen from the group made up of isocyanates, carbodiimides, aziridines and alkoxysilanes, per molecule of crosslinking agent.

A document comprising:

• a base sheet;
• variable inscriptions associated with said base sheet;
• and
• at least one adhesive layer comprising at least one thermoplastic polymer, said adhesive layer extending in contact with an extreme layer of said base sheet,
• wherein said thermoplastic polymer is chosen from the group made up of thermoplastic polymers having a hydroxyl number, measured according to standard DIN 53 240/2, of between 3 mg of KOH/g and 60 mg of KOH/g, thermoplastic polymers having an acid number, measured according to the standard DIN EN ISO 2114, of between 2 mg of KOH/g and 150 mg of KOH/g, copolymers thereof and blends thereof,
• wherein said thermoplastic polymer has a glass transition temperature, measured by differential scanning calorimetry, of between 40° C. and 110° C., and
• wherein said adhesive layer also comprises at least one crosslinking agent, each crosslinking agent:
• being chosen from the group of aliphatic compounds comprising between 4 and 50 carbon atoms, having on average at least 2.8 functions, chosen from the group made up of isocyanates, carbodiimides, aziridines and alkoxysilanes, per molecule of crosslinking agent.