Patent ID: 7108897

Claim:
A polyvinyl alcohol polarizing film containing, in a substrate for the polarizing film, a water soluble dye represented by the following formula (1) in the form of a free acid: wherein A represents the following formula (2): B represents the following formula (4): n is 1, R 5 in the formula (4) represents an amino group or a hydroxyl group, R 1, R 2, R 3, R 4 each independently represents a hydrogen atom, methyl group, ethyl group, methoxy group, ethoxy group and acetyl amino group, or a copper complex salt dye thereof, with the proviso that the following compounds and copper complex salts thereof are excluded: (1) a compound wherein all of R 1 , R 2 , R 3 and R 4 are methyl groups, and R 5 in the formula (4) represents an amino group or a hydroxyl group, (2) a compound wherein all of R 1 , R 2 , R 3 and R 4 are methoxy groups and R 5 in the formula (4) represents an amino group or a hydroxyl group, and (3) a compound wherein R 1 and R 3 are methyl groups and R 2 and R 4 are methoxy groups, and R 5 in the formula (4) represents an amino group or a hydroxyl group.