| 摘要 |
PROBLEM TO BE SOLVED: To enhance a recording density and to improve reliability for a long period by incorporating at least one of cyanine dye represented by a formula as one main component as an organic dye film dealing with a short wavelength laser beam in a recording layer. SOLUTION: Cyanine dye represented by a formula is used for a recording layer 2. The dye has absorbing and reflecting wavelength in about 500 to 700 nm in the case of reducing its film thickness, and has sufficient sensitivity and reflectivity for laser wavelength (about 600 to 680 nm). Particularly, when substituents R1 , R2 are respectively allyl vinyl, allylidene, allyleoxy, crotonoyl, styryl, vinylidene, vinylene, methylidyne, acrylxy, methacryloxy, isopropenyl, ethynyl, or butenyl, compatibility between film formability and a surface of a board is satisfactory. Number of carbons is preferably 3 to 18, and more preferably about 3 to 9. In addition, when substituents of Y1 and Y2 are introduced asymmetrically, edition or association of dyes can be suppressed. |
