Patent ID: 8350015

Claim:
A cyanine dye which is represented by Formula 1 and which exhibits an absorption maximum at a wavelength of longer than 400 nm but not higher than 550 nm and efficiently absorbs visible radiation ranging from 400 nm to 550 nm in the violet to green region in a solution and has a molar absorption coefficient (ε) of at least 5×10 4 at the absorption maximum wavelength, and which has a residual dye rate (%) of at least 99.3% when determined on determining an optical transmittance (T 0 ) of said cyanine dye in the form of a thin membrane formed on a glass plate at an absorption maximum wavelength of about 450 nm, exposing said thin membrane to a 7.5 W xenon lamp with a light-irradiation energy of 180 w/m 2 on the surface of said glass plate for 5.5 hours in the ventilation of cooled air, determining an optical transmittance (T) at the absorption maximum wavelength, and calculating the residual dye rate (%) with the following equation: Residual ⁢ ⁢ dye ⁢ ⁢ rate ⁢ ⁢ ( % ) = × 100 = 100 - T 100 - T 0 × 100 wherein in Formula 1, Z 1 and Z 2 mean monocyclic, condensed carbocyclic or heterocyclic aromatic rings which are the same or different from each other, and R 1 to R 6 independently denote aliphatic hydrocarbon groups which optionally bear a substituent.