To obtain a dichroic dye-type polarizing film excellent in polarizing performances such as hue and excellent in durability under high-temperature high-humidity conditions by orienting a novel azo compound being a hey which covers a relatively long wavelength region and another organic dye on a polymer film base by adsorption.
An azo compound represented by the formula (Q1 is phenyl substituted with at least one sulfo or carboxyl group or naphthyl substituted with at least one sulfo group; R1 and R2 are each H, hydroxyl or amino) is used as a dye for a polarizing film. Desirably, Q1 is originated in e.g. 1- aminobenzene-4-sulfonic acid or 2-aminonaphthalene-6,8- or 5,7-disulfonic acid. Desirably, the compound of formula I is used in the form of a sodium salt. By using a combination of the azo compound of formula I with the organic dye, the hue can be corrected to attain improved polarizing performances. The base material used to make a polarizing film is exemplified by polyvinyl alcohol or a derivative thereof.
HAYASHI SHIGETOSHI
YOKOYAMA KANEO
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