Azo compound and salt thereof, and dye-based polarizing film and polarizing plate containing the same

A dye-based polarizing film containing in a raw film for a polarizing film, an azo compound and/or a salt thereof, which is represented by the following formula (7):

• in the formula (7), A represents a naphthyl group having a substituent;
• R1 to R6 each independently represent a hydrogen atom, an alkyl group having a carbon atom number of 1 to 5, an alkoxy group having a carbon atom number of 1 to 5, a sulfo group or an alkoxy group having a sulfo group and a carbon atom number of 1 to 5, X represents a phenylamino group, a phenylazo group, or a naphthotriazole group,
• wherein A is a naphthyl group represented by the following formula (6):
• in the formula (6), R13 represents a hydrogen atom, a sulfo group, a hydroxy group, or an alkoxy group having a sulfo group and a carbon atom number of 1 to 5, and n represents 1 to 3;
• wherein the phenylamino group is represented by the following formula (2):
• in the formula (2), R7 and R8 each independently represent a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group or a substituted amino group;
• wherein the phenylazo group is represented by the following formula (5):
• in the formula (5), R10 to R12 each independently represent a hydrogen atom, a hydroxy group, an alkyl group having a carbon atom number of 1 to 5, an alkoxy group having a carbon atom number of 1 to 5, an amino group or a substituted amino group;
• and
• wherein the naphthotriazole group is represented by the following formula (4):
• in the formula (4), m represents 1 or 2.