Patent ID: 6346364
Filing Date: 2002-02-12
Classification: G11B,Y10S,Y10T

Abstract:
An optical information recording medium comprising:i) a light transmitting substrate, a light absorptive layer containing at least one light absorbing substance formed on the substrate and a light reflective layer made of a metal film formed on the light absorptive layer, wherein the imaginary part kabs at 780 nm of the complex refractive index of the light absorptive layer is 0.001&lE;kabs&lE;0.2 and wherein the light absorbing substance in the light absorptive layer is at least one cyanine dye represented by the formula: â€ƒwherein each of A and Aâ€² which may be the same or different is a group of atoms forming a naphthalene ring or a substituted naphthalene ring, B is pentamethylene (â€”C&boxH;CHâ€”CH&boxH;CHâ€”CH&boxH;), of which each hydrogen atom may be substituted by a halogen atom, an alkyl group, an alkoxy group or a diphenylamino group, or which may have a substituted or unsubstituted cyclic side chain bridging a plurality of carbon atoms, each of R1 and R1â€² which may be the same or different is a substituted or unsubstituted alkyl, alkoxy, alkylhydroxy, aralkyl, alkenyl, alkylcarboxyl or alkylsulfonyl group, or a substituted or unsubstituted alkylcarboxyl or alkylsulfonyl group bonded to an alkali metal ion or an alky group, and X1âˆ’ is an anion selected from the group consisting of a halogen atom, perchloric acid, borofluoric acid, benzenesulfonic acid, toluenesulfonic acid, an alkylsulfonic acid, a benzenecarboxylic acid, an alkylcarboxylic acid and a trifluoromethylcarboxylic acid, provided that when R1 and R1â€² have a group bonded to an alkali metal ion, X1âˆ’ may be not present.