Patent ID: 7704309

Claim:
A process for printing an image on a substrate comprising applying to the substrate by means of an ink jet printer an ink comprising a compound of Formula (1) or salt thereof: wherein: R 4 , R 5 , R 6 and R 7 are each independently H or an optionally substituted substituent or R 4 and R 5 and/or R 6 and R 7 together with the carbon atoms to which they are attached form an optionally substituted aryl or heterocyclic ring; X and Z are each independently H or an optionally substituted substituent; R 1 is H or optionally substituted C 1-4 -alkyl; R 2 and R 3 are each independently H, C 1-4 -alkyl, —CONR 8 R 9 , SO 2 NR 8 R 9 or aryl groups; wherein R 8 and R 9 are each independently H, optionally substituted C 1-8 -alkyl, an optionally substituted aryl or heterocyclic ring, or R 8 and R 9 together with the nitrogen atom to which they are attached form an optionally substituted 5- or 6-membered ring; G and G′ are each independently a sulfonic acid group, carboxylic acid group or phosphonic acid group; n and m are each independently is 0, 1, 2, 3, 4 or 5; and a and b are each independently 0, 1 or 2.