Abstract: The present invention relates to an azo compound represented by the following formula (1): wherein A denotes a phenyl group having 1 to 3 substituents such as sulfonic acid group, amino group, lower alkyl groups and lower alkoxyl groups, or a naphthyl group, B denotes hydrogen atom, sulfonic acid group, a lower alkyl group, a lower alkoxyl group or the like, each of R1 to R4 independently denotes hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or the like, D denotes —NHCO—, —N?N— or —NH—, E denotes hydrogen atom, a lower alkyl group or a phenyl group having 1 to 3 substituents such as hydroxyl group and amino group, n denotes 0 or 1, and m denotes 0 or 1, or a salt thereof, or a copper complex compound of either of them, which is used for a polarizing plate having excellent polarization performance and durability and furthermore little color leakage in visible light range.

Abstract: A polarizing film or polarizing plate containing, as a dichroic dye, an azo compound whose free acid form is represented by the following formula (1): wherein R1 and R2 each independently represents sulfo, carboxy, lower alkyl, or lower alkoxy; R3 represents lower alkyl, lower alkoxy, or acetylamino; R4 to R6 each independently represents hydrogen, lower alkyl, lower alkoxy, or acetylamino; and R7 represents hydrogen, amino, or hydroxy. The polarizing film and plate are excellent in polarizing performance and durability and are highly reduced in color leakage in the visible light region.

Abstract: The present invention relates to an azo compound represented by the following formula (1): wherein A denotes a phenyl group having 1 to 3 substituents such as sulfonic acid group, amino group, lower alkyl groups and lower alkoxyl groups, or a naphthyl group, B denotes hydrogen atom, sulfonic acid group, a lower alkyl group, a lower alkoxyl group or the like, each of R1 to R4 independently denotes hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxyl group or the like, D denotes —NHCO—, —N?N— or —NH—, E denotes hydrogen atom, a lower alkyl group or a phenyl group having 1 to 3 substituents such as hydroxyl group and amino group, n denotes 0 or 1, and m denotes 0 or 1, or a salt thereof, or a copper complex compound of either of them, which is used for a polarizing plate having excellent polarization performance and durability and furthermore little color leakage in visible light range.