Laser-markable substrate, and associated manufacturing method

Abstract

The present invention relates to a laser-markable substrate, comprising at least one material capable of forming a colored mark under laser irradiation and at least one tamper-proof agent producing an irreversible visible coloration when an attempt is made to chemically erase the mark.

1 . A laser-markable substrate, comprising:
 at least one material able to form a colored mark under laser irradiation; and   at least one antitampering agent producing an irreversible visible coloration when an attempt is made to chemically remove the colored mark.   
     
     
         2 . The substrate as claimed in  claim 1 , the antitampering agent being incorporated into the thickness of the substrate by impregnation, facing, coating or spraying. 
     
     
         3 . The substrate as claimed  claim 1 , the antitampering agent making it possible to prevent chemical removal of the mark containing at least one of the following compounds:
 an oxidizing agent;   a strong or weak base;   a strong or weak acid; or   a polar or nonpolar solvent.   
     
     
         4 . The substrate as claimed in  claim 1 , the antitampering agent making it possible to prevent chemical removal of the mark using oxidizing agents and being chosen from:
 derivatives of manganese, nickel, cobalt or cerium;   pp-diaminodiphenyl, its sulfate derivatives or its phosphate derivatives;   vanadium derivatives;   4,4′-diaminodinaphthyl (1,1′);   S,N-orthophenylene isothiourea;   primuline;   guanidine derivatives; or   derivatives of thiazole, benzothiazole or aminonaphthothiazole.   
     
     
         5 . The substrate as claimed in  claim 1 , the antitampering agent making it possible to prevent chemical removal using strong and/or weak bases and being chosen from:
 derivatives of manganese, nickel, cobalt or cerium;   colored indicators.   
     
     
         6 . The substrate as claimed in  claim 1 , the antitampering agent making it possible to prevent chemical removal of the mark using weak and/or strong acids and being chosen from:
 a colored indicator;   ferric chloride added to potassium ferrocyanide; or   a thiazole derivative, benzothiazole or aminonaphthothiazole.   
     
     
         7 . The substrate as claimed in  claim 1 , the antitampering agent making it possible to prevent chemical removal with polar and/or nonpolar solvents and being chosen from dyes that are insoluble in water but soluble in oils and solvents. 
     
     
         8 . The substrate as claimed in  claim 1 , the antitampering agent being a manganese derivative. 
     
     
         9 . The substrate as claimed in  claim 1 , the at least one material able to form a colored mark under laser irradiation being incorporated into the thickness of the substrate by impregnation, facing, coating or spraying. 
     
     
         10 . The substrate as claimed in  claim 1 , the at least one material being able to be marked by a UV laser or by an infrared laser, in particular a CO2 laser and/or a YAG laser. 
     
     
         11 . The substrate as claimed in  claim 1 , said colored mark having a relief. 
     
     
         12 . The substrate as claimed in  claim 1 , the at least one material able to form a mark being chosen from derivatives of mica, molybdates, tungstates and vanadates. 
     
     
         13 . The substrate as claimed in  claim 1 , further comprising a mineral filler absorbent in the infrared. 
     
     
         14 . The substrate as claimed in  claim 1 , further comprising polyvinyl alcohol (PVA). 
     
     
         15 . The substrate as claimed in  claim 1 , wherein the substrate is based on cellulose fibers. 
     
     
         16 . The substrate as claimed in  claim 1 , wherein the substrate is a plastic substrate. 
     
     
         17 . The substrate as claimed in  claim 1 , further comprising at least one authenticating and/or identifying security element. 
     
     
         18 . The substrate as claimed in  claim 1 , wherein the concentration of material able to form a colored mark lying between 0.1 and 10% by dry weight relative to the weight of the substrate. 
     
     
         19 . The substrate as claimed in  claim 1 , wherein the concentration of the at least one antitampering agent lying between 0.01 and 5% by dry weight relative to the weight of the substrate. 
     
     
         20 . A security document and/or a security article, comprising:
 a laser-markable substrate, comprising:
 at least one material able to form a colored mark under laser irradiation, and 
 at least one antitampering agent producing an irreversible visible coloration when an attempt is made to chemically remove the colored mark. 
   
     
     
         21 . A method of manufacturing a laser-markable substrate as claimed in  claim 1 , comprising:
 introducing into the thickness of the substrate, by impregnation or by facing during manufacture of the substrate in a paper machine, material of the substrate able to form a colored mark under laser irradiation.