Method of minimizing visible coloration of substrate

Abstract

A method of minimizing visible coloration of a substrate having an IR-absorbing dye disposed thereon. The method includes preselecting the dye such that it includes a moiety for reducing intermolecular interactions between adjacent dye molecules.

1 . A method of minimizing visible coloration of a substrate having an IR-absorbing dye disposed thereon, said method comprising preselecting said dye such that it includes a moiety for reducing intermolecular interactions between adjacent dye molecules. 
   
   
       2 . The method of  claim 1 , wherein said dye is disposed in the form of a coded data pattern. 
   
   
       3 . The method of  claim 1 , wherein said coded data pattern is a position-coding pattern. 
   
   
       4 . The method of  claim 1 , wherein said substrate comprises an interface surface and wherein the coded data is disposed over a substantial portion of said interface surface. 
   
   
       5 . The method  claim 1 , wherein said substrate is a paper sheet, a label, a tag, a packaging material or a product item. 
   
   
       6 . The method of  claim 1 , wherein said dye is an IR-absorbing metal-dithiolene dye of formula (II): 
     
       
         
         
             
             
         
       
     
     wherein:
 M is selected from Ni, Pd or Pt (preferably Ni); 
 j is selected from 1, 2, 3 or 4; 
 k is selected from 1, 2, 3 or 4; 
 n is 0, 1, 2 or 3; 
 W is selected from: a substituent comprising an ammonium group; a substituent comprising an acid group, including salts thereof, or a substituent comprising a sulfonamide group; 
 up to three —(CH 2 )— groups in the carbocycle are optionally replaced by a group independently selected from —C(O)—, —NH—, —S—, —O—; 
 up to three —CH— groups in the carbocycle may be optionally replaced by —N—; and 
 up to four H atoms in the carbocycle may be optionally replaced by a group independently selected from C 1-6  alkyl, C 1-6  alkoxy, C 5-12  aryl, C 5-12  arylalkyl, halogen, hydroxyl or amino. 
 
   
   
       7 . The method of  claim 6 , wherein M is Ni. 
   
   
       8 . The method of  claim 6 , wherein j is 1 and k is 2. 
   
   
       9 . The method of  claim 6 , wherein n is 1. 
   
   
       10 . The method of  claim 9 , wherein W is a substituent comprising a group of formula —CO 2 Z, —SO 3 Z, —OSO 3 Z, —PO 3 Z or —OPO 3 Z, wherein Z is H or a water-soluble cation. 
   
   
       11 . The method of  claim 9 , wherein W is of formula —(CH 2 ) t —SO 3 Z, wherein t is 0 or an integer from 1 to 6, and Z is H or a water-soluble cation. 
   
   
       12 . The method of  claim 9 , wherein W is of formula —CH 2 SO 3 H, —CH 2 SO 3 Na or —CH 2 SO 3 K.