| abstract |
An ink composition comprising an oxygen sensitive dye capable of fluorescing, such as a dye comprising ruthenium (II), osmium (II), iridium (III), rhodium (III) and chromium ions with a ligand, such as a a-diimine ligand, such as 2,2'-bipyridine, 1,10-phenanthroline, 4,7-diphenyl-1-10-phenanthroline, 4,7-disulphonated-diphenyl-1,10-phhenathroline, 5 -bromo-1,10-phenathroline or 5-chloro- 1,10-phenanthroline, an example is tris(2.2' - bipyridine)ruthenium(II) salt, tris(1,10-phenanthroline)ruthenium (II) salt or tris(4,7-diphenyl-1-10-phenanthroline)ruthenium (II) salt; and a polymer matrix for the dye wherein the polymer matrix comprises a copolymer of an acrylic monomer or oligomer and an ethylenically unsaturated containing one or more sulphonic acid or phosphonic acid groups. Also disclosed is a substrate printed or coated with the ink composition. |