Azo compounds containing two 6-hydroxypyrid-2-one coupling component radicals the nitrogen atoms of which are linked by a biscationic radical

A compound of the formula ##STR58## or a mixture thereof, wherein each A is independently linear or branched C.sub.2-6 alkylene or linear or branched C.sub.3-6 alkylene substituted by hydroxy,

• each D is independently the radical of a diazo component of the benzene, azobenzene or naphthalene series,
• E.sub.1a is linear or branched C.sub.2-4 alkylene;
• linear or branched C.sub.3-4 alkylene monosubstituted by hydroxy;
• linear or branched C.sub.2-6 alkylene interrupted by --O--, --NR.sub.9 -- or ##STR59## or linear or branched C.sub.3-8 alkylene monosubstituted or disubstituted by hydroxy and interrupted by --O--, --NR.sub.9 -- or ##STR60## wherein R.sub.9 is hydrogen or C.sub.1-6 alkyl, and
• R.sub.10 is hydrogen, halo, C.sub.1-4 alkyl or C.sub.1-4 alkoxy,
• each R.sub.1 is independently hydrogen, C.sub.1-4 alkyl, cyclohexyl, phenyl or phenyl(C.sub.1-2 alkyl),
• each R.sub.2 is independently hydrogen, cyano, --COOR.sub.5, --CONR.sub.6 R.sub.7 or ##STR61## wherein R.sub.5 is hydrogen, C.sub.1-4 alkyl or phenyl(C.sub.1-2 alkyl),
• each of R.sub.6 and R.sub.7 is independently hydrogen or C.sub.1-4 alkyl,
• each R.sub.8 is independently C.sub.1-4 alkyl, and r is 0, 1, 2 or 3,
• each R.sub.3 is independently C.sub.1-4 alkyl or C.sub.1-4 alkyl monosubstituted by halo, cyano, hydroxy or phenyl,
• each R.sub.4 is independently hydrogen, C.sub.1-4 alkyl or C.sub.1-4 alkyl monosubstituted by halo, cyano, hydroxy or phenyl
• each An.crclbar. is a non-chromophoric anion, and
• n is , 1, 2, 3, 4, 5 or 6,
• with the proviso that the negative charges of the An.crclbar.'s balance the positive charge of each cationic group of the molecule not balanced by the negative charge of an anionic group of the molecule.