Sulfonyloxy substituted tris-azoaryl dyes and copper complex salts thereof and polarizing films dyed therewith

A water-soluble dye composition comprising an azo dye represented by the following formula (1) or a copper complex salt dye obtained by complexing the azo dye with copper and represented by the following formula (7):

• ##STR113## wherein A means a benzene or naphthalene ring having a sulfonic acid group or a salt thereof, Y and Z individually denote a group of the following formula (a):
• ##STR114## and Z.sup.2 denotes a group of the following formula (b):
• ##STR115## wherein R.sup.2 is a hydrogen atom, a methyl group, a methoxyl group or an ethoxyl group and R.sup.3 is a methyl, methoxyl or ethoxyl group,
• R.sup.1 represents an amino, C.sub.1-4 alkylamino, C.sub.2-4 alkylcarboxyamino, benzoylamino or phenylamino group bonded to the 6 or 7 position of the naphthalene ring, and X denotes a hydrogen, sodium, potassium or lithium atom, with the proviso that Y and Z are different but, when both R.sup.2 s are hydrogen atoms and both R.sup.3 s are methoxyl groups, Y and Z may be the same, and the formula (1) is not complexed with copper when R.sup.3 in Z is a methyl group.