Write-once optical discs having good reflectivity - comprise transparent substrate coated with penta:methin cyanine mixt., and reflective layer

摘要

Optical discs have a transparent substrate (I) coated with an organic dyestuff recording layer (II) and then a reflective layer (III). The novelty is that (II) contains a pentamethine cyanine mixt. contg. pentamethin cyanine(s) (IV) of the formula (I) where R = alkyl; W = H, aryl, an aromatic gp. or halogen; and X = I. (I) consists of polycarbonate, polymethyl methacrylate or polyolefin and pref. has a pre-address or pre-groove. (III) is a thin Al, Au, Cu or Ag film. ADVANTAGE - (II) is stable for long periods and has high reflectivity and a narrow absorption wavelength band. .