Patent ID: 7876666
Filing Date: 2011-01-25
Classification: G11B

Abstract:
1. A write-once information recording medium comprising: a transparent resin substrate having a concentrically or spirally shaped groove and a land formed thereon; and a recording film formed on the groove and the land of the transparent resin substrate, wherein the groove has a width ranging from 1.05 to 1.5 when the land has a width of 1, and the recording film has a recording mark formed thereon by emission of short wavelength laser light whose wavelength is about 405 nm, a light reflectivity of the recording mark formed by the emission of the short wavelength laser light being higher than a light reflectivity of the recording film on which no recording mark is formed by emission of short wavelength laser light, and wherein the recording film has an absorbance in a range of about 0.3 to 0.5 while in a recording wavelength range of about 405 nm, wherein the recording film includes an organic coloring matter whose maximum absorption wavelength region exists on a wavelength side which is longer than a wavelength of the short wavelength laser light; the organic coloring matter has a coloring matter portion which is made of a coloring matter represented by general formula 3 and has an anion portion that is a mixed color matter of a first coloring matter which is made of an organic metal complex that is mainly composed of metal such as cobalt and represented by general formula 4 and a second coloring matter which is made of C wherein exactly one of R in general formula 3, Z1 and Z2 represent mutually same or different aromatic rings, and these aromatic rings each may have a substituent; Y11 and T12 each represent a carbon atom or a hetero atom, independently; R11 and R12 represent aliphatic hydrocarbon groups, and these aliphatic hydrocarbon groups each may have a substituent; and R13, R14, R15, and R16 each represent a hydrogen atom or a proper substituent, independently, and when Y11 and T12 are hetero atoms, part or all of R13, R14, R15, and R16 are absent, and in general formula 4, M represents cobalt; A and A′ represent mutually same or different complex ring groups of five rings to ten rings, containing one or more hetero atoms selected from a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom, such as a furyl group, a thienyl group, a pyridyl group, a piperidino group, a piperidyl group, a quinolyl group, and an iso-oxazolyl group; Y21 and Y22 are mutually same or different hetero atoms selected from the elements of group XVI in the periodic table, such as an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom; R21 to R24 each represents a hydrogen atom, or halogen groups such as a fluoro group, a chloro group, a bromo group and an iodo group, or aliphatic hydrocarbon groups such as a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methyl pentyl group, a 2-methyl pentyl group, a hexyl group, an isohexyl group and a 5-methyl hexyl group, or alicyclic hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and a 1-cyclohexenyl group, or an ether group, or a carbonyl group, or an acetoxy group, or an ester group, or an alkyl sulfamoyl group, or a sulfoamino group, or a cyano group, or a nitro group; and an azo compound is prepared by reaction between a diazonium salt having R21, R22, or R23, R24 corresponding to the general formula, and a complex ring compound having an active methylene group adjacent to a carboxyl group in the molecule, for example, an iso-oxazolone compound, an oxazolone compound, a thionaphthene compound, a pyrazolone compound, a barbituric acid compound, a hydantoin compound, and a rhodanine compound.