| abstract |
This refers to an ink composition that contains (a) a compound of the formula: Lm-Ln3 + (Ch-) n in which Ln represents a lanthanide, Ch- is a negatively charged ligand containing at least one double bond UV absorber, n denotes 3 or 4, m denotes a number from 1 to 4, in the case where n is 3, m denotes a number from 1 to 4 and L is a neutral ligand absorber of UV, monodentate or polydentate containing nitrogen, oxygen or sulfur, with the exception of 2,2'-bipyridyl or, in the case where n is 4, m denotes 1 and L is a single-charge cation; and (b) a carrier of liquid ink, which can be used to apply hidden marks on objects, which can only be disclosed under UV exposure. |