JP3834053B2 - Optical recording medium - Google Patents

Description

  The present invention relates to an optical recording medium.

  With the advent of the multimedia era, optical recording media such as CD-R (write-once memory using a compact disk) and DVD-R (write-once memory using a digital video disk) are in the spotlight. The optical recording medium is composed of an inorganic optical recording medium comprising a recording layer using an inorganic substance such as tellurium, selenium, rhodium, carbon, hydrogen sulfide, and an organic constituting the recording layer by a light absorber mainly composed of an organic dye compound. The optical recording medium can be broadly classified.

  Among these, the organic optical recording medium is usually an organic dye compound such as a polymethine dye such as 2,2,3,3-tetrafluoro-1-propanol (hereinafter abbreviated as “TFP”). After dissolving in an organic solvent, applying the solution to a polycarbonate substrate and drying to form a recording layer, a reflective layer made of a metal such as gold, silver, copper, etc. It is produced by forming. Compared to inorganic media, organic optical recording media have the disadvantage that the recording layer is easily changed by ambient light such as reading light or natural light, but the light absorber is applied directly to the substrate as a solution. Thus, the recording layer can be configured, so that there is an advantage that an optical recording medium can be manufactured at a low cost. In addition, since the organic optical recording medium is mainly composed of an organic substance, it has an advantage that it is difficult to corrode even in an environment exposed to moisture or seawater, and the appearance of an organic heat-deformable optical recording medium has a predetermined value. Since information recorded in an optical recording medium in a format can be read using a commercially available read-only device, it is now becoming the mainstream of inexpensive optical recording media.

  An urgent problem in the organic optical recording medium is further densification to cope with the multimedia era. At present, the research on high density that is actively promoted in this field is mainly by shortening the wavelength of the laser beam used for writing information from the current 775 to 795 nm to 660 nm or less by the GaAlAs semiconductor laser, It aims to increase the recording capacity per side to 4.7 GB or more. However, for example, in DVD-R, which is expected as a high-density optical recording medium to replace CD-R, it is proposed to use laser light with a wavelength of 660 nm or less as writing light. Many of the developed organic dye compounds cannot substantially absorb such writing light on the long wavelength side of the absorption maximum, so when used for DVD-R, information cannot be properly written or read. Has been considered. Therefore, in this field, a wide variety of organic dye compounds that substantially absorb visible light having a wavelength of 660 nm or less on the long wavelength side of the absorption maximum have been experimentally produced and optical characteristics of DVD-R are being tested. However, when a new molecular design of an organic dye compound is made, a great deal of cost and labor are required to establish a method for producing the organic dye compound itself, in addition to tests for optical properties and stability.

  As described above, the present invention is an organic dye compound that is conventionally considered to be inapplicable to an optical recording medium, but substantially absorbs writing light on the short wavelength side of the absorption maximum. This is based on a unique finding that it can be used very advantageously as a light absorber that is a main component of forming pits on a substrate of a recording medium. The present invention uncovers the potential uses of organic dye compounds that were conventionally considered to be inapplicable to optical recording media, and therefore, optical recording media, and in particular, high-density optical recording media using writing light having a wavelength of 700 nm or less. In this case, the choice of the organic dye compound that mainly forms pits on the substrate is greatly expanded.

  In view of such circumstances, the object of the present invention is to discover potential uses of organic dye compounds that have been conventionally considered to be inapplicable to optical recording media, and thus organic dye compounds used in producing optical recording media The challenge is to expand the options.

  As a result of diligent research by the present inventors, even organic dye compounds that were conventionally considered to be inapplicable to optical recording media are those that substantially absorb writing light on the short wavelength side of the absorption maximum. The present inventors have found that the present invention is extremely useful as a light absorber that mainly forms pits on a substrate of a recording medium.

  That is, this invention includes the above-described problem, comprising a substrate and a recording layer provided on the substrate using an organic dye compound, and irradiating the recording layer with writing light to In the optical recording medium for recording information by forming pits on the substrate, the problem is solved by providing an optical recording medium in which the absorption maximum of the organic dye compound is longer than the wavelength of the writing light. .

  Furthermore, the present invention provides the above-described problem by including a substrate and a recording layer provided on the substrate using an organic dye compound, and irradiating the recording layer with writing light, In an optical recording method for recording information by forming pits on a substrate, an organic dye compound that substantially absorbs writing light on the short wavelength side of the absorption maximum as an organic dye compound that mainly forms pits This is solved by providing an optical recording method in which pits are formed on a substrate by irradiating writing light having a wavelength shorter than the absorption maximum wavelength.

  Furthermore, this invention solves the above-mentioned subject by providing the organic pigment | dye compound used for such an optical recording medium and an optical recording method.

  The embodiment of the present invention will be described. The organic dye compound in the present invention means all organic compounds having an atomic group that absorbs visible light in the molecule, and the organic dye compound has a covalent bond between atoms. Even if it couple | bonds by only, it may couple | bond together through a covalent bond and noncovalent bonds, such as an ionic bond and a coordination bond, for example. In this invention, as long as it is an organic dye compound that satisfies such requirements and that substantially absorbs writing light on the short wavelength side of the absorption maximum, it has a specific chemical structure or preparation method. However, the present invention can be used very advantageously. Note that the absorption maximum in the present invention refers to the absorption maximum in a thin film state unless otherwise specified.

  The organic dye compound used in the present invention has one or more substituents at both ends of a polymethine chain such as a monomethine chain or dimethine chain, trimethine chain, tetramethine chain, pentamethine chain, hexamethine chain, and heptamethine chain which may have one or more substituents. Or an imidazoline ring, an imidazole ring, a benzimidazole ring, an α-naphthimidazole ring, a β-naphthimidazole ring, an indole ring, an isoindole ring, an indolenine ring, an isoindolenin ring, Benzoindolenin ring, pyridinoindolenin ring, oxazoline ring, oxazole ring, isoxazole ring, benzoxazole ring, pyridinooxazole ring, α-naphthoxazole ring, β-naphthoxazole ring, selenazoline ring, selenazole ring, benzoselena Ring, α-naphthselenazole ring, β-naphthselenazole ring, thiazoline ring, thiazole ring, isothiazole ring, benzothiazole ring, α-naphthothiazole ring, β-naphthothiazole ring, tellrazoline ring, tellurazole ring, Benzotelrazole ring, α-naphthotelrazole ring, β-naphthotelrazole ring, acridine ring, anthracene ring, isoquinoline ring, isopyrrole ring, imidanoxaline ring, indandione ring, indazole ring, indarin ring, oxadiazole Ring, carbazole ring, xanthene ring, quinazoline ring, quinoxaline ring, quinoline ring, chroman ring, cyclohexanedione ring, cyclopentanedione ring, cinnoline ring, thiodiazole ring, thiooxazolidone ring, thiophene ring, thionaphthene ring, thiobarbitu Luric acid ring, thiohydantoin ring, tetrazole ring, triazine ring, naphthalene ring, naphthyridine ring, piperazine ring, pyrazine ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, pyrazolone ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, Pyrylium ring, pyrrolidine ring, pyrroline ring, pyrrole ring, phenazine ring, phenanthridine ring, phenanthrene ring, phenanthroline ring, phthalazine ring, pteridine ring, furazane ring, furan ring, purine ring, benzene ring, benzoxazine ring, benzopyran ring Polymethine colors such as cyanine dyes, merocyanine dyes, oxonol dyes, azulenium dyes, squarylium dyes, pyrylium dyes, thiopyrylium dyes, phenanthrene dyes, which are formed by bonding of cyclic nuclei such as morpholine and rhodanine rings In addition to acridine, azaannulene, azo metal complex, anthraquinone, indigo, indanthrene, oxazine, xanthene, dioxazine, thiazine, thioindigo, tetrapyraporphyrazine, triphenylmethane And dyes based on triphenothiazine, naphthoquinone, phthalocyanine, benzoquinone, benzopyran, benzofuranone, porphyrin, and rhodamine.

  A particularly desirable organic dye compound is a metal complex of a cyanine dye, a styryl dye or an azo compound represented by any one of the general formulas 1 to 3, having an absorption maximum at a wavelength shorter than 850 nm, and optical recording. When used as a medium, it substantially absorbs writing light having a wavelength of 700 nm or less, particularly writing light having a wavelength of 390 to 450 nm or wavelengths of 630 to 680 nm on the short wavelength side of the absorption maximum.

Through the general formulas 1 and 2, Z1 to Z3 represent aromatic rings such as benzene ring, naphthalene ring, pyridine ring, quinoline ring, quinoxaline ring, etc., and these aromatic rings have one or more substituents. It may be. Examples of the substituent include, for example, methyl group, trifluoromethyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. , Tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, hexyl group, isohexyl group, 5-methylhexyl group, heptyl group, octyl group and other aliphatic hydrocarbon groups, cyclopropyl group, cyclobutyl group, Cyclopentyl group, cyclohexyl group and other alicyclic hydrocarbon groups, phenyl group, biphenylyl group, o-tolyl group, m-tolyl group, p-tolyl group, xylyl group, mesityl group, o-cumenyl group, m-cumenyl group , Aromatic hydrocarbon group such as p-cumenyl group, methoxy group, trifluoromethoxy group, ethoxy , Propoxy group, isopropoxy group, butoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, phenoxy group, benzoyloxy group and other ether groups, methoxycarbonyl group, trifluoromethoxycarbonyl group, ethoxycarbonyl group, Ester groups such as propoxycarbonyl group, acetoxy group, benzoyloxy group, halogen groups such as fluoro group, chloro group, bromo group, iodo group, thio groups such as methylthio group, ethylthio group, propylthio group, butylthio group, phenylthio group, Sulfides such as methylsulfamoyl, dimethylsulfamoyl, ethylsulfamoyl, diethylsulfamoyl, propylsulfamoyl, dipropylsulfamoyl, butylsulfamoyl, and dibutylsulfamoyl Amoyl group, primary amino group, methylamino group, dimethylamino group, ethylamino group, diethylamino group, propylamino group, dipropylamino group, isopropylamino group, diisopropylamino group, butylamino group, dibutylamino group, piperidino Group such as amino group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group, dipropylcarbamoyl group and the like, and further, hydroxy group, carboxy group, cyano group, nitro group, A sulfino group, a sulfo group, a mesyl group, etc. are mentioned. In the general formula 1, Z ₁ and Z ₂ may be the same or different from each other.

Y _{1 to} Y ₃ in General Formula 1 and General Formula 2 represent a carbon atom or a hetero atom. Examples of the hetero atom include a periodic table such as a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. And group 15 and group 16 atoms. The carbon atom in Y _{1 to} Y ₃ may be an atomic group mainly composed of two carbon atoms such as ethylene group and vinylene group. Y ₁ and Y ₂ in general formula 1 may be the same or different from each other.

In the general formulas 1 and 2, R ₁ and R ₂ and R _{7 to} R ₉ represent an aliphatic hydrocarbon group. Examples of aliphatic hydrocarbon groups include, for example, methyl, ethyl, propyl, isopropyl, isopropenyl, 1-propenyl, 2-propenyl, butyl, isobutyl, sec-butyl, tert -Butyl group, 2-butenyl group, 1,3-butadienyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, 2-pentenyl group, hexyl group, Examples thereof include an isohexyl group, a 5-methylhexyl group, a heptyl group, an octyl group, and the like. Such an aliphatic hydrocarbon group may have one or more substituents similar to those in Z _{1 to} Z ₃ . Note that R ₁ and R _{2 in the} general formula ₁ and R _{7 to} R ₉ in the general formula 2 may be the same as or different from each other.

R _{3 to} R ₅ and R ₁₀ and R ₁₁ in the general formula 1 and the general formula 2 each independently represent a hydrogen atom or an appropriate substituent in each general formula. Examples of the substituent include, for example, methyl group, trifluoromethyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. , Tert-pentyl group, 1-methylpentyl group, 2-methylpentyl group, hexyl group, isohexyl group, 5-methylhexyl group, heptyl group, octyl group and other aliphatic hydrocarbon groups, methoxy group, trifluoromethoxy group , Ethoxy group, propoxy group, butoxy group, tert-butoxy group, ether group such as pentyloxy group, phenoxy group, benzoyloxy group, halogen group such as fluoro group, chloro group, bromo group, iodo group, and Group, carboxy group, cyano group, nitro group and the like. In General Formula 1 and General Formula 2, when Y _{1 to} Y ₃ are heteroatoms, a part or all of R _{3 to} R ₆ in Z ₁ and Z ₂ , and R ₁₀ and R ₁₁ in Z ₃ are used. One or both of them will not exist.

L ₁ and L ₂ in Formula 1 and Formula 2 represents a polymethine chain, the L ₁ in the general formula 1, for example, trimethine chain, pentamethine chain, such as heptamethine chain, formed by continuous odd number of methine groups from the polymethine chain, and as the L ₂ in formula 2, for example, dimethine chain, Tetoramechin chain, such as hexamethine chain, an even number of methine groups selected from polymethine chains comprising continuous. Such a polymethine chain may have a substituent and / or a cyclic group. Examples of the substituent include a methyl group, a trifluoromethyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. Group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, aliphatic hydrocarbon group such as tert-pentyl group, methoxy group, trifluoromethoxy group, ethoxy group, propoxy group, butoxy group, Ether groups such as tert-butoxy group, halogen groups such as fluoro group, chloro group, bromo group and iodo group, amino groups such as diphenylamino group and p-methoxydiphenylamino group, nitro group, cyano group and the like Examples of the cyclic group include a cyclopentene ring and a cyclohexene ring. That. Incidentally, as the light absorber in the optical recording medium using the writing light having a wavelength of around 660 nm, an organic dye compound represented by the general formula 1 in which L ₁ is a heptamethine chain is desirable. Further, when the organic dye compound represented by the general formula 1 or 2 is applied to an optical recording medium using a writing light having a wavelength of around 405 nm, L ₁ and L ₂ are respectively a trimethine chain and a dimethine. Those having a chain are desirable.

X ₁ and X ₂ in the general formula 1 and formula 2 is a counter ion may be as appropriate taking into account the stability in solubility and glass state of the organic dye compound in an organic solvent, usually, fluorine ions , Chlorine ion, bromine ion, iodine ion, perchlorate ion, periodate ion, hexafluorophosphate ion, hexafluoroantimonate ion, hexafluorostannate ion, nitrate ion, phosphate ion, borofluoride Inorganic acid anions such as acid ion and tetrafluoroborate ion, salicylic acid, p-hydroxysalicylic acid, thiocyanate ion, benzenesulfonate ion, naphthalenesulfonate ion, naphthalene disulfonate ion, p-toluenesulfonate ion, alkylsulfonic acid Ion, benzenesulfonate ion, alkylcarboxylate ion, trihaloalkylcarboxylic acid Organic acid anions such as ions, alkyl sulfate ions, trihaloalkyl sulfate ions, nicotinate ions, azo, bisphenyldithiol, thiocatechol chelate, thiobisphenolate chelate, bisdiol-α-diketone, etc. Selected from cations such as trimethylammonium ion and triethylammonium ion.

Explaining the general formula 3, Z ₄ and Z ₅ represent the same or different aromatic hydrocarbon or heterocyclic group, and examples of the aromatic hydrocarbon group include a phenyl group, a biphenylyl group, a naphthyl group, and the like. Examples of the heterocyclic group include pyridyl group, quinolyl group, isoxazolyl group, isothiazolyl group, imidazolyl group, oxazolyl group, thiodiazolyl group, pyrazolyl group and the like. Such an aromatic hydrocarbon group and heterocyclic group may have one or more substituents, and examples of the substituent include, for example, the same as in Z _{1 to} Z ₃ of General Formula 1 and General Formula 2. The substituent of this is mentioned. R ₁₂ in the general formula 3 represents an acidic group such as a phenolic hydroxy group, a carboxy group, a sulfino group, or a sulfo group, and these acidic groups may be in the form of a salt with an inorganic base or an organic base. .

  The azo compound represented by the general formula 3 is usually used in the form of a metal complex in which one or more of them are coordinated to a metal (center atom). The metal serving as the central atom is usually a metal element belonging to Group 3 to Group 12 in the periodic table, and is, for example, an atom, an oxide, or a halide such as fluoride, bromide, or iodide. There are the following. Examples of such metal elements include scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium. Nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury and the like.

A metal complex having a divalent metal (M) as a central atom is desirable, and in particular, a metal complex represented by the general formula 4. In General Formula 4, Az is an azo compound represented by General Formula 3, and m represents the number of azo compounds as a ligand (A _z ) coordinated to M, and is usually 1 or 2. . D suitably represents a counter ion, and n is the number of D for maintaining the charge balance in the complex. The azo metal complex used in the present invention usually takes a -2, 0, or monovalent charge, but when the charge is zero, n is zero, and therefore D does not exist. Examples of the counter ion D include hexafluorophosphate ion, fluorate ion, bromate ion, iodate ion, nitrate ion, phosphate ion, perchlorate ion, periodate ion, hexafluoroantimonate ion, six Fluorostannate ion, borofluoride ion, tetrafluoroborate ion, thiocyanate ion, benzenesulfonate ion, naphthalenesulfonate ion, benzenecarboxylate ion, alkylcarboxylate ion, trihaloalkylcarboxylate ion, alkyl Examples include anions such as sulfate ion, trihaloalkylsulfate ion, and nicotinate ion, and cations such as ammonium ion and tetraalkylammonium ion.

  In the organic dye compounds represented by the general formulas 1 to 3, when there is an isomer such as a cis / trans isomer in the structure, any isomer is included in the present invention. To do.

  Examples of the organic dye compound used in the present invention include those represented by chemical formulas 1 to 38. Among these, those represented by chemical formulas 1 to 19 are optical recording media using writing light having a wavelength of 630 to 680 nm, and those represented by chemical formulas 20 to 38 are those having a wavelength of 390 to 450 nm. This is extremely useful in an optical recording medium using incident light. Any of the organic dye compounds represented by Chemical Formula 1 to Chemical Formula 38 substantially absorbs the writing light as described above on the short wavelength side of the absorption maximum. That is, all of the organic dye compounds represented by Chemical Formulas 1 to 19 have an absorption maximum at a wavelength longer than 680 nm, and substantially write light having a wavelength of 630 to 680 nm on the short wavelength side of the absorption maximum. Absorb. The organic dye compounds represented by the chemical formulas 20 to 38 all have an absorption maximum at a wavelength longer than 450 nm, and substantially write light having a wavelength of 390 to 450 nm on the short wavelength side of the absorption maximum. Absorb. Incidentally, the organic dye compound represented by Chemical Formula 2 shows a visible absorption spectrum as shown in FIG. 1 in a thin film state. Obviously from the visible absorption spectrum of FIG. 1, the organic dye compound represented by the chemical formula 2 has an absorption maximum near wavelengths of 730 nm and 820 nm, respectively, and writing light near a wavelength of 660 nm is emitted on the short wavelength side of these absorption maximums. Absorbs substantially. Any of the compounds represented by Chemical Formulas 1 to 38 can be obtained in a desired amount according to a known method or according to a known method for preparing an analogous compound.

  As described above, the present invention includes a substrate and a recording layer provided on the substrate using an organic dye compound. The recording layer is irradiated with writing light to form an organic dye compound. The main application target is an optical recording medium that records information by forming pits on a substrate.

  Such an optical recording medium can be produced according to a conventionally known optical recording medium by using the organic dye compound of the present invention. As a general method, for example, the organic dye compound as described above and one of the other dye compounds having sensitivity to visible light, if necessary, in order to adjust the light reflectance and light absorption rate in the recording layer, or Add one or more general light resistance improvers, binders, dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc., and then dissolve in an organic solvent. After forming a thin film to be a recording layer by uniformly applying to one side of the substrate by spraying, dipping, roller coating, spin coating, etc. and drying, if necessary, the light reflectance is 45% or more Desirably, gold, silver, copper, platinum, aluminum, cobalt, tin, nickel, iron, chromium, vacuum deposition method, chemical vapor deposition method, sputtering method, ion plating method etc. In order to protect the recording layer from scratches, dust, dirt, etc., with a flame retardant, stable A protective layer that adheres to the reflective layer is formed by applying an ultraviolet curable resin, a thermosetting resin, or the like containing an agent, an antistatic agent, or the like, and curing by irradiation with light or heating. Thereafter, if necessary, the pair of substrates on which the recording layer, the reflective layer, and the recording layer are formed as described above are bonded with the protective layers facing each other with, for example, an adhesive or an adhesive sheet, or A protective plate of the same material and shape as in the substrate is attached to the protective layer. The method for forming the recording layer should not be limited to the method of applying the organic dye compound as a solution. For the organic dye compound having a sublimation property, other methods such as vacuum deposition, A thin film of an organic dye compound may be formed directly on the substrate by a method such as vapor deposition or atomic layer epitaxy.

  Examples of the light resistance improver include nitroso compounds such as nitrosodiphenylamine, nitrosoaniline, nitrosophenol, nitrosonaphthol, tetracyanoquinodimethane compounds, diimmonium salts, bis [2′-chloro-3-methoxy-4- ( 2-methoxyethoxy) dithiobenzyl] nickel (trade name “NKX-1199” manufactured by Hayashibara Biochemical Laboratories Co., Ltd.), metal complexes such as azo metal complexes and formazan metal complexes are used. Are used in appropriate combination. Desirable light fastness improving agents are those comprising a nitroso compound or a formazan metal complex, and particularly desirable is Japanese Patent Application No. 11-88983 (name of the invention "phenylpyridylamine derivative") by the same patent applicant. Or a pyridine ring at position 5 in the formazan skeleton disclosed in Japanese Patent Application No. 11-163036 (name of invention “formazan metal complex”). And a formazan compound in which a pyridine ring or a furan ring is bonded to the position 3 or a tautomer thereof, for example, nickel, zinc, cobalt, iron, It comprises a metal complex with copper, palladium or the like. When used in combination with such a light fastness improver, the organic dye compound by exposure to reading light, ambient light, etc. without reducing the solubility of the organic dye compound in the organic solvent or substantially impairing the desired optical properties Undesirable changes such as deterioration, discoloration, discoloration, and modification can be effectively suppressed. As a compounding ratio, usually, a light fastness improver is contained in an amount of 0.01 to 5 mol, preferably 0.1 to 2 mol, with respect to 1 mol of the organic dye compound.

  As an organic solvent for applying an organic dye compound to a substrate, TFP frequently used in the production of optical recording media, or hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, isopropylcyclohexane, tert-butylcyclohexane, Hydrocarbons such as octane, cyclooctane, benzene, toluene, xylene, carbon tetrachloride, chloroform, 1,2-dichloroethane, 1,2-dibromoethane, trichloroethylene, tetrachloroethylene, chlorobenzene, bromobenzene, α-dichlorobenzene, etc. Halide, methanol, ethanol, 2,2,2-trifluoroethanol, 2-methoxyethanol (methyl cellosolve), 2-ethoxyethanol (ethyl cellosolve), 2 Isopropoxy-1-ethanol, 1-propanol, 2-propanol, 1-ethoxy-2-propanol, 1-ethoxy-2-propanol, 1-butanol, 1-methoxy-2-butanol, 3-methoxy-1-butanol , 4-methoxy-1-butanol, isobutyl alcohol, pentyl alcohol, isopentyl alcohol, cyclohexanol, diethylene glycol, triethylene glycol, propylene glycol, glycerin, diacetone alcohol, phenols, benzyl alcohol, cresol and other alcohols and phenols , Diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, anisole, 1,2-dimethoxyethane, diethylene glycol di Ethers such as methyl ether, dicyclohexyl-18-crown-6, methyl carbitol, ethyl carbitol, furfural, acetone, 1,3-diacetylacetone, ethyl methyl ketone, ketones such as cyclohexanone, ethyl acetate, butyl acetate, Esters such as ethylene carbonate, propylene carbonate and trimethyl phosphate, amides such as formamide, N-methylformamide, N, N-dimethylformamide and hexamethylphosphoric triamide, nitriles such as acetonitrile, propionitrile, succinonitrile and benzonitrile , Nitro compounds such as nitromethane, nitrobenzene, amines such as ethylenediamine, pyridine, piperidine, morpholine, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, etc. Select sulfur-containing compounds from the general-purpose organic solvents other than TFP including, if necessary, or a mixture of them.

  The substrate may be a general-purpose one, and usually an appropriate material is obtained by an extrusion molding method, an injection molding method, an extrusion injection molding method, a photopolymer method (2P method), a thermosetting integral molding method, a photocuring integral molding method, or the like. Depending on the final application, for example, it is formed into a disk shape having a diameter of 12 cm and a thickness of 0.6 mm or 1.2 mm, and this is used as a single plate, or it is used by suitably bonding with an adhesive sheet, an adhesive or the like. The material of the substrate is not particularly limited as long as it is substantially transparent and has a transmittance of 80% or more, preferably 90% or more with respect to light in the wavelength range of 400 to 800 nm. . Examples of the individual materials include glass, ceramic, polymethyl methacrylate, polycarbonate, polystyrene (styrene copolymer), polymethylpentene, polyetherimide, polyethersulfone, polyarylate, polycarbonate / polystyrene-alloy, Plastics such as polyester carbonate, polyphthalate carbonate, polycarbonate acrylate, amorphous polyolefin, methacrylate copolymer, diallyl carbonate diethylene glycol, and epoxy resin are used, and polycarbonate is usually used frequently. In the case of a plastic substrate, the sync signal and the recess for displaying the track and sector addresses are usually transferred to the track inner circumference during molding. Although there is no particular limitation on the shape of the concave portion, it is desirable that the average width is in the range of 0.1 to 0.8 μm and the depth is in the range of 20 to 300 nm.

  When the recording layer is formed by applying the organic dye compound to the substrate, the organic dye compound is made into a solution having a concentration of 0.5 to 5% (w / w) in the organic solvent as described above, and after drying. The recording layer is uniformly coated on the substrate so that the thickness of the recording layer is 10 to 1,000 nm, preferably 50 to 500 nm. Prior to the application of the solution, an undercoat layer may be provided on the substrate as necessary for the purpose of protecting the substrate and improving adhesion. Examples of the material of the undercoat layer include ionomer resins. , Polymer materials such as polyamide resin, vinyl resin, natural resin, silicon, and liquid rubber. When using a binder, cellulose esters such as nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose palmitate, cellulose acetate / propionate, methyl cellulose, ethyl cellulose, propyl cellulose, Cellulose esters such as butyl cellulose, polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl acetal, polyvinyl butyral, polyvinyl formal, polyvinyl alcohol, polyvinyl pyrrolidone and other vinyl resins, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-butadiene -Acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, maleic anhydride copolymer Copolymer resins such as polymethyl methacrylate, polymethyl acrylate, polyacrylate, polymethacrylate, polyacrylamide, polyacrylonitrile and other acrylic resins, polyethylene terephthalate and other polyesters, polyethylene, chlorinated polyethylene, polypropylene and other polyolefins In addition, the polymer such as is used alone or in combination and is used in a weight ratio of 0.01 to 10 times that of the organic dye compound.

  The method of using the optical recording medium according to the present invention will be described. A high-density optical recording medium such as a DVD-R according to the present invention is, for example, a GaN-based, AlGaInP-based, GaAsP-based, GaAlAs-based, InGaP-based, InGaAsP-based or InGaAlP-based Or a laser beam having a wavelength of 680 nm or less, particularly 390 to 450 nm, or a Nd-YAG laser combined with a second harmonic generation element (SHG element) such as a distributed feedback type or a Bragg reflection type, Various kinds of information can be written with high density using laser light of 630 to 680 nm. For reading, a laser beam having the same wavelength as that for writing or slightly higher wavelength is used. Regarding the laser output at the time of writing and reading, although it depends on the kind and blending amount of the light fastness improver used in combination with the organic dye compound in the present invention, the optical recording medium according to the present invention is used for writing information. It is desirable to set the output of the laser beam to be relatively stronger than the threshold value of energy for forming pits, while the output when reading written information is set to be relatively weaker than the threshold value. Generally, writing is performed in a range exceeding 4 mW and not exceeding 50 mW, and reading is adjusted in a range of 0.1 to 4 mW. The recorded information is read by detecting a change in the amount of reflected light or the amount of transmitted light at a portion where no pit is formed on the recording surface of the optical recording medium by an optical pickup.

  Thus, in the optical recording medium according to the present invention, by using a pickup with a laser beam having a wavelength of 700 nm or less, a track pitch of less than 1.6 μm employed in the current standard CD-R is 0.834 μm. / It is possible to form minute pits having a pit length below the pit with high density. Therefore, for example, when a disk-shaped substrate having a diameter of 12 cm is used, the recording capacity that cannot be easily achieved by the current standard CD-R exceeds 0.682 GB on one side (usually 4 on one side). .7 GB or more), an extremely high density optical recording medium capable of recording images and sounds for about two hours can be realized.

  The optical recording medium according to the present invention can record character information, image information, audio information, and other digital information with high density, so that it can be used for recording and managing documents, drawings, data, computer programs, etc. In addition, it is extremely useful as a business recording medium. Examples of individual industries that can use the optical recording medium according to the present invention and the form of information include, for example, construction and civil engineering drawings in construction and civil engineering, maps, road and river accounts, aperture cards, architectural sketches, disaster prevention materials, and wiring diagrams. , Layout drawings, newspaper / magazine information, regional information, construction reports, etc., manufacturing drawings, composition tables, prescriptions, product specifications, product price lists, parts lists, maintenance information, accident / failure cases, complaint cases Collection, manufacturing process table, technical data, drawings, details, in-house collection, technical report, inspection report, etc., customer information in sales, business partner information, company information, contract, newspaper / magazine information, sales report, Corporate credit surveys, inventory lists, financial company information, stock price records, statistical materials, newspaper / magazine information, contracts, customer lists, various applications / reports / licenses / licensing documents, operations Medical records such as notifications, real estate / transport property information, building sketches, maps, regional information, power / gas wiring / piping diagrams, disaster prevention materials, work standards tables, survey materials, technical reports, etc. Medical history / case files, medical charts, textbooks, problem collections, educational materials, statistical materials, etc., academic papers, academic records, monthly research reports, research data, literature and literature indexes, etc. , Survey data in information, papers, patent gazettes, weather maps, data analysis records, customer files, legal precedents, tourism information in tourism, traffic information, etc. Index of in-house publications in the media / publishing, newspaper / magazine information , People files, sports records, telop files, broadcast scripts, maps related to government offices, roads and rivers Ledger, fingerprint files, resident card, various types of application and notification and licensing, licensing documents, statistical data, such as public documents, and the like. In particular, the optical recording medium of the present invention, which can be written only once, must not have the recorded information altered or erased. For example, in addition to record storage of medical records and official documents, such as museums, libraries, museums, broadcasting stations, etc. It is extremely useful as an electronic library.

  The optical recording medium according to the present invention has some special applications such as a compact disk, digital video disk, laser disk, MD (information recording system using a magneto-optical disk), CDV (laser disk using a compact disk), DAT (magnetic). Information recording system using tape), CD-ROM (read-only memory using compact disc), DVD-RAM (writable read memory using digital video disc), digital photograph, movie, video software, audio Examples include editing, proofreading of software, computer graphics, publications, broadcast programs, commercial messages, game software, etc., as well as large computer and external program recording means for car navigation.

  Hereinafter, embodiments of the present invention will be described based on examples.

<Optical recording medium>
As a light absorber, an organic dye compound represented by any one of Chemical Formula 20, Chemical Formula 23, Chemical Formula 26, Chemical Formula 30 or Chemical Formula 35 having an absorption maximum at a wavelength longer than 405 nm is added to TFP at a concentration of 2% (w / w). Furthermore, a nitroso compound represented by the chemical formula 39 as a light fastness improving agent is added to a concentration of 0.5% (w / w), heated for a while, and then applied with ultrasonic waves. Dissolved. According to a conventional method, this solution is subjected to membrane filtration, and then a polycarbonate disk-shaped substrate (diameter: 12 cm, thickness: 0.6 mm) in which a recess indicating the sync signal and the track and sector addresses is transferred to the track inner periphery. ) Was uniformly spin-coated on one side and dried to form a recording layer having a thickness of 120 nm. Thereafter, a reflective layer that adheres to the recording layer is formed by sputtering silver to a thickness of 100 nm on the substrate, and a known ultraviolet curable resin (trade name “Dicure Clear SD1700”, Dainippon, Japan) is formed on the reflective layer. Ink Chemical Industry Co., Ltd.) is uniformly applied by spin coating, and after forming a protective layer that adheres to the reflective layer by irradiating with light, it is adhered to the protective layer to form a disk-shaped protective plate made of polycarbonate (diameter 12 cm, thickness 0) .6 mm) was attached to produce an optical recording medium.

  All of the optical recording media of this example have a recording capacity exceeding 15 GB, and a large amount of document information, image information, audio information, and other digital information can be collected at high density by using a laser element having an oscillation wavelength of about 405 nm. Can be written on. When the recording surface of the optical recording medium of the present example in which information was written using a semiconductor laser element having an oscillation wavelength of 405 nm was observed with an electron microscope, minute pits less than 1 μm / pit were formed at a high density with a track pitch less than 1 μm. It had been.

  As described above, the present invention is an organic dye compound that is conventionally considered to be inapplicable to an optical recording medium, but substantially absorbs writing light on the short wavelength side of the absorption maximum. This is based on a unique finding that it can be used very advantageously as a light absorber that is a main component of forming pits on a substrate of a recording medium. The present invention uncovers the potential uses of organic dye compounds that were conventionally considered to be inapplicable to optical recording media, and therefore, optical recording media, and in particular, high-density optical recording media using writing light having a wavelength of 700 nm or less. In this case, the choice of the organic dye compound that mainly forms pits on the substrate is greatly expanded.

  It can be said that this invention having such remarkable effects is a very significant invention that contributes to the world.

It is a visible absorption spectrum in the thin film state of the organic pigment | dye compound used by this invention.

Claims (1)

In an optical recording medium comprising a recording layer containing an organic dye compound, and recording information by irradiating the recording layer with laser light having a wavelength of about 405 nm as the writing light, the organic dye compound contains the writing light. An optical recording medium, which has a maximum absorption at a wavelength longer than the wavelength, substantially absorbs writing light, and is a compound represented by any one of the following general formulas 1 to 3 .
In General Formula 1, Z ₁ and Z ₂ represent the same or different aromatic rings, and these aromatic rings may have a substituent. Y ₁ and Y ₂ each independently represents a carbon atom or a hetero atom. R ₁ and R ₂ represent an aliphatic hydrocarbon group, and these aliphatic hydrocarbon groups may have a substituent. R _{3 to} R ₆ each independently represent a hydrogen atom or an appropriate substituent, and when Y ₁ and Y ₂ are heteroatoms , part or all of R _{3 to} R ₆ does not exist. L ₁ represents a methine chain, and the methine chain may have a substituent and / or a cyclic group. X ₁ represents an appropriate counter ion.
In General Formula 2, Z ₃ represents an aromatic ring, and the aromatic ring may have a substituent. Y ₃ represents a carbon atom or a hetero atom. R _{7 to} R ₉ represent the same or different aliphatic hydrocarbon groups, and these aliphatic hydrocarbon groups may have a substituent. R ₁₀ and R ₁₁ each independently represent a hydrogen atom or an appropriate substituent, and when Y ₃ is a hetero atom, R ₁₀ and / or R ₁₁ does not exist. L ₂ represents a methine chain, and the methine chain may have a substituent and / or a cyclic group. X ₂ represents an appropriate counter ion.
In General Formula 3, Z ₄ and Z ₅ represent the same or different aromatic hydrocarbon group or heterocyclic group, and these aromatic hydrocarbon group and heterocyclic group may have a substituent. R ₁₂ represents an acidic group.