JP4183918B2 - Optical recording medium and optical recording method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-capacity write-once optical recording medium for data and an optical recording method.
[0002]
[Prior art]
a. Prior art of write-once recording media (WORM) (for information recording)
[0003]
(1) Using cyanine dye as a recording material
JP-A-57-82093, 58-56892, 58-12790, 58-1149889, 59-85791, 60-83236, 60-89842, 61-25886
[0004]
(2) Using phthalocyanine dye as a recording material
JP 61-150243, 61-177287, 61-154888, 61-24609, 62-39286, 63-37991, 63-39888
[0005]
b. Conventional technology of write-once compact disc (CD-R)
(1) Using a cyanine dye + metal reflective layer as a recording material
JP-A-1-159842, 2-42652, 2-13656, 2-168446
[0006]
(2) Using phthalocyanine dye + metal reflective layer as a recording material
JP-A-1-176585, 3-215466, 4-113886, 4-226390, 5-1272, 5-171052, 5-116456, 5-96860, 5-139044, 5-139044
[0007]
(3) Using azo metal chelate dye + metal reflective layer as recording material
JP-A-4-46186, 4-141489, 4-361808, 5-279580, 7-51673, 7-161069, 7-37272, 7-71867, 8-231866, 8-295811
[0008]
c. Conventional technology of large capacity write once compact disc (DVD-R)
[0009]
(1) Using a cyanine dye + metal reflective layer as a recording material
PIONEER R & D vol. 6 No. 2 (1996): Development of DVD-Recordable, basic development of DVD-R dye disk
ISOM / ODS '96 (1996): High density of recording on Dye material Disc profor for 4.7G
JP 10-235999 A
[0010]
(2) Azomethine dye + metal reflective layer used as a recording material
JP-A-8-198872, 8-209002, 8-283263, 10-273484
[0011]
(3) Using azo metal chelate dye + metal reflective layer as recording material
JP-B-5-67438, JP-A-7-161069, 8-156408, 8-231866, 8-332772, 9-58123, 9-175031, 9-193545, 9-274732, 9-277703, 10-6644, 10- 6650, 10-6651, 10-36693, 10-44606, 10-58828, 10-86519, 10-149584, 10-157293, 10-157300, 10-157301, 10-157302, 10-181199, 10-181201 10-181203, 10-181206, 10-188340, 10-188341, 10-188358, 10-208303, 10-214423, 10-228671, 11-12383, 11-28865, 11-42858, 11 134708,11-208111
[0012]
(4) Other dyes + metal reflective layer used as a recording material
JP-A-10-86517, 10-93788, 10-226172, 10-244752, 10-287819, 10-297103, 10-309871, 10-309872
[0013]
(5) Azo metal chelate dye + other dye + metal reflective layer used as a recording material
JP-B-7-51682, JP-A-11-34499, 11-48612, 11-105424
[0014]
[Problems to be solved by the invention]
Currently, DVD-R is being developed as a next generation large capacity optical disk. Development of recording materials for minimizing recording pits, adoption of image compression technology represented by MPEG2, and shortening of semiconductor laser wavelength for reading recording pits are necessary as elemental technologies for improving recording capacity. .
[0015]
Up until now, only 670 nm band AlGaInP laser diodes have been commercialized for bar code readers and measuring instruments as semiconductor lasers in the red wavelength range. It is being used in the optical storage market. In the case of a DVD drive, it is standardized with a wavelength of a laser diode in the 630 to 670 nm band as a light source. On the other hand, a read-only DVD-ROM drive is commercialized at a wavelength of about 650 nm.
[0016]
Under such circumstances, the most preferable DVD-R medium is a medium that can be recorded and reproduced at a wavelength of 630 to 670 nm. However, a recording material that has excellent light resistance and storage stability and can be recorded and reproduced with an optical pickup using a laser of 670 nm or less has not been developed yet.
[0017]
One of the recording layers of an optical recording medium for recording / reproducing with an optical pickup using a laser having a wavelength of 630 to 670 nm is a squarylium dye. However, this dye is significantly deteriorated in light and poor in stability. An azo metal chelate dye is a dye exhibiting high light resistance, but media using this dye in the recording layer have problems such as low reflectance.
[0018]
The present invention is a recording material in an optical recording medium applicable to a DVD-R disk system using a semiconductor laser having an oscillation wavelength at a shorter wavelength than the conventional system, in particular, an optical recording medium using a conventional squarylium dye. An object of the present invention is to provide a recording material excellent in light resistance and storage stability and a recording method using the recording material.
[0019]
[Means for Solving the Problems]
As a result of various investigations on means for solving the above problems, the present inventors have configured a recording layer mainly composed of a mixture of a squarylium dye and a dye having a specific structure, thereby forming a semiconductor laser having an oscillation wavelength of 670 nm or less. It has been found that an optical recording medium that can be applied to a next-generation large-capacity optical disk system to be used and that is excellent in light resistance and storage stability can be obtained.
[0020]
That is, the present invention provides an optical recording medium having a recording layer provided on a substrate, a squarylium compound in the recording layer, and the following general formula (I):
[Chemical 1]
[Where: A represents a 6 atom aromatic ring not containing N; B represents a residue which, together with the carbon atom to which it is attached, forms an optionally substituted aromatic ring or optionally substituted heterocycle, X is an active hydrogen An optical recording medium comprising at least one azo compound and an azo metal chelate compound comprising a metal, and the optical recording medium. It relates to a recording method.
[0021]
In the optical recording medium of the present invention, the recording layer contains at least one kind of squarylium compound and an azo metal chelate compound composed of an azo compound represented by the general formula (I) and a metal. An optical recording medium in which the compound is prevented from being photodegraded and excellent in light resistance can be obtained.
[0022]
Among the squarylium compounds used in the optical recording medium of the present invention, the following general formula (II)
[Chemical 7]
[In the formula, R ₁ And R ₂ Are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aryl group which may have a substituent. R ₁ And R ₂ May form a heterocyclic ring which may have a substituent together with the adjacent nitrogen atom. R _Three Represents the following general formula (III) or (IV):
[Chemical 8]
[Wherein R _Four And R _Five Are the same or different and each represents a hydrogen atom or an alkyl group, or R _Four And R _Five Together with the adjacent nitrogen atom forms an optionally substituted heterocyclic ring, R ₆ , R ₇ , R ₈ And R ₉ Are the same or different and each represents a hydrogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, a hydroxyl group or a halogen atom; _Four And R ₆ Or R _Five And R ₇ May form a heterocyclic ring containing a nitrogen atom together with adjacent N—C—C, and the heterocyclic ring may have a substituent.
[Chemical 9]
[Where Q ₁ Represents a carbon atom or a nitrogen atom, R _Ten And R ₁₁ Are the same or different and are a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent or a hydroxyl group (however, Q ₁ R is a nitrogen atom, R ₁₁ Is not present) and R ₁₂ Represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent or an aralkyl group which may have a substituent; ₁₃ And R ₁₄ Are the same or different and each represents a hydrogen atom, an optionally substituted alkyl group, an alkoxy group or a halogen atom, or R ₁₃ And R ₁₄ Together with two adjacent carbon atoms form an alicyclic hydrocarbon ring, an optionally substituted aromatic ring or an optionally substituted heterocycle. ]] Or a compound represented by the following general formula (V)
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[Where Q ₂ Represents a carbon atom or a nitrogen atom, R ₁₅ Represents a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent or a heterocyclic group which may have a substituent, and R ₁₆ Has a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents an aryl group, an amino group which may have a substituent, or a heterocyclic group which may have a substituent. R ₁₇ And R ₁₈ Are the same or different and each represents an optionally substituted alkyl group, or R represents ₁₇ And R ₁₈ May combine with adjacent carbon atoms to form an alicyclic hydrocarbon ring or heterocycle. However, Q ₂ R is a nitrogen atom, R ₁₈ Does not exist. R ₁₉ Represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent, R ₂₀ Is a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a trifluoromethyl group, a nitro group, a cyano group Or an alkoxy group which may have a substituent. n represents an integer of 0 to 4, and when n is 2 to 4, _{twenty one} May be the same or different, and two Rs adjacent to each other ₂₀ May form an aromatic ring which may have a substituent together with two adjacent carbon atoms.] Is preferable.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The mixing ratio of the squarylium compound and the azo metal chelate compound in the optical recording medium is 90:10 to 10:90, preferably 80:20 to 15:85, more preferably 80:20 to 30:70 by weight. is there. When the squarylium compound is in the above range, the azo metal chelate compound works effectively and high light resistance is obtained. Moreover, since a high reflectance is obtained when the squarylium compound is in the above range, it is preferable.
[0024]
Specific examples of A and B in the general formula (I) include residues that form a benzene ring, a naphthalene ring, a pyridine ring, a quinoline ring, and the like. These aromatic rings or heterocyclic rings may have a substituent. Specific examples of the substituent are independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxyl group, a carboxyl group, an amino group, a carbamoyl group, a mercapto group, an optionally substituted alkyl group, and a substituent. An aryl group which may have a group, a heterocyclic residue which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, An alkylthio group which may have a substituent, an arylthio group which may have a substituent, an alkylamino group which may have a substituent, an arylamino group which may have a substituent, An alkoxycarbonyl group which may have a substituent, an aryloxycarbonyl group which may have a substituent, an alkylcarboxamide group which may have a substituent, and may have a substituent. An arylcarboxamide group, an optionally substituted alkylcarbamoyl group, an optionally substituted arylcarbamoyl group, an optionally substituted alkenyl group, and an optionally substituted substituent Good alkylsulfamoyl groups and the like can be mentioned.
[0025]
Alkyl groups having 1 to 9 carbon atoms (straight or branched) and 3 to 14 (cyclic) are suitable, and specific examples thereof include methyl, ethyl, n-propyl, and n-butyl. Group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group and other linear alkyl groups, isobutyl group, isoamyl group, 2-methylbutyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 2-ethylbutyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2-ethyl Pentyl group, 3-ethylpentyl group, 2-methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 2-ethylhexyl group, 3-ethylhexyl group, i Propyl group, sec-butyl group, 1-ethylpropyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1-methylheptyl group, 1-ethylbutyl group, 1,3-dimethylbutyl group, 1,2- Dimethylbutyl group, 1-ethyl-2-methylpropyl group, 1-methylhexyl group, 1-ethylheptyl group, 1-propylbutyl group, 1-isopropyl-2-methylpropyl group, 1-ethyl-2-methylbutyl group 1-propyl-2-methylpropyl group, 1-ethylhexyl group, 1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl-2-methylbutyl group, 1-isopropyl-3-methylbutyl group, 1-methyloctyl Group, 1-propylhexyl group, 1-isobutyl-3-methylbutyl group, neopentyl group, tert-butyl Group, tert-hexyl group, tert-amyl group, branched alkyl group such as tert-octyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- (2 -Ethylhexyl) A cycloalkyl group such as a cyclohexyl group, a bornyl group, an isobornyl group (adamantyl group), and the like.
[0026]
The alkyl group is substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, an aryl group which may have a substituent, a heterocyclic residue which may have a substituent, or the like. Also good. Further, it may be substituted with the above alkyl group or aryl group through an atom such as oxygen, sulfur, or nitrogen.
[0027]
Examples of the alkyl group substituted through oxygen include methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group, butoxyethyl group, ethoxyethoxyethyl group, phenoxyethyl group, methoxypropyl group, ethoxypropyl group, etc. However, examples of the alkyl group substituted through sulfur include a methylthioethyl group, an ethylthioethyl group, an ethylthiopropyl group, a phenylthioethyl group, and the like, and examples of the alkyl group substituted through nitrogen include dimethyl An aminoethyl group, a diethylaminoethyl group, a diethylaminopropyl group, etc. are mentioned.
[0028]
Specific examples of the aryl group include a phenyl group, a naphthyl group, an anthranyl group, a fluorenyl group, a phenalenyl group, a phenanthryl group, a triphenylenyl group, and a pyrenyl group.
[0029]
The aryl group is substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, an aryl group which may have a substituent, a heterocyclic residue which may have a substituent, or the like. In addition, the above alkyl group may be substituted through an atom such as oxygen, sulfur, nitrogen or the like.
[0030]
Specific examples of the heterocyclic residue include furyl group, thienyl group, pyrrolyl group, benzofuryl group, isobenzofuranyl group, benzothienyl group, indolinyl group, isoindolinyl group, carbazolyl group, pyridyl group, piperidyl group, quinolyl group, Examples thereof include an isoquinolyl group, an oxazolyl group, an isoxazolyl group, a thiazolyl group, an isothiazolyl group, an imidazolyl group, a pyrazolyl group, a benzimidazolyl group, a pyrazyl group, a pyrimidinyl group, a pyridazinyl group, and the like.
[0031]
The heterocyclic residue is substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, an aryl group which may have a substituent, a heterocyclic residue which may have a substituent, or the like. It may be substituted with an alkyl group through an atom such as oxygen, sulfur, or nitrogen.
[0032]
Specific examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.
[0033]
The alkoxy group is not particularly limited as long as an alkyl group which may have a direct substituent is bonded to the oxygen atom, and specific examples of the alkyl group include the specific examples described above.
[0034]
The aryloxy group may be any group in which an aryl group which may have a direct substituent is bonded to an oxygen atom, and specific examples of the aryl group include the specific examples described above.
[0035]
The alkylthio group may be any group in which an alkyl group which may have a direct substituent is bonded to the sulfur atom, and specific examples of the alkyl group include the specific examples described above.
[0036]
The arylthio group only needs to be bonded to an aryl group which may have a substituent directly on the sulfur atom, and specific examples of the aryl group include the specific examples described above.
[0037]
The alkylamino group may be any group in which an alkyl group which may have a direct substituent is bonded to the nitrogen atom, and specific examples of the alkyl group include the above-described specific examples. In addition, alkyl groups may be bonded to each other to form a ring such as a piperidino group, a morpholino group, a pyrrolidinyl group, a piperazinyl group, an indolinyl group, an isoindolinyl group and the like including an oxygen atom and a nitrogen atom.
[0038]
The arylamino group may be any group in which an aryl group which may have a direct substituent is bonded to the nitrogen atom, and specific examples of the aryl group include the specific examples described above.
[0039]
The alkoxycarbonyl group may be any group in which an alkyl group which may have a direct substituent is bonded to the oxygen atom of O (C═O). Specific examples of the alkyl group include the specific examples described above. Can be mentioned.
[0040]
The aryloxycarbonyl group may be any group in which an aryl group which may have a direct substituent is bonded to the oxygen atom of O (C═O). Specific examples of the aryl group include the specific examples described above. Can be mentioned.
[0041]
The alkylcarboxamide group may be any group in which an alkyl group which may have a direct substituent is bonded to the carbon atom of carboxysamide. Specific examples of the alkyl group include the specific examples described above. it can.
[0042]
The aryl carboxamide group may be any group in which an aryl group which may have a direct substituent is bonded to the carbon atom of carboxysamide. Specific examples of the aryl group include the above-described specific examples. it can.
[0043]
The alkylcarbamoyl group may be any group in which an alkyl group that may have a direct substituent is bonded to the nitrogen atom of the carbamoyl group, and specific examples of the alkyl group may include the specific examples described above. . In addition, alkyl groups may be bonded to each other to form a ring such as a piperidino group, a morpholino group, a pyrrolidinyl group, a piperazinyl group, an indolinyl group, an isoindolinyl group and the like including an oxygen atom and a nitrogen atom.
[0044]
The arylcarbamoyl group may be any group in which an aryl group which may have a direct substituent is bonded to the nitrogen atom of the carbamoyl group, and specific examples of the aryl group can include the above-described specific examples. .
[0045]
The alkylsulfamoyl group may be any group in which an alkyl group which may have a direct substituent is bonded to the nitrogen atom of the sulfamoyl group, and specific examples of the alkyl group include the above-described specific examples. Can do.
[0046]
Specific examples of the substituent having an active hydrogen group of X include a hydroxyl group, a carboxyl group, an amino group, an alkylcarboxamide group, an arylcarboxamide group, an alkylsulfonamide group, an arylsulfonamide group, a carbamoyl group, an alkylcarbamoyl group, and an arylcarbamoyl group. Group, sulfo group, sulfino group, sulfeno group, sulfamoyl group, thiol group and the like.
[0047]
Specific examples of the alkylcarboxamide group, arylcarboxamide group, alkylcarbamoyl group, and arylcarbamoyl group include the above-described specific examples.
[0048]
Specific examples of the alkylsulfonamide group may be those in which an alkyl group that may have a direct substituent is bonded to the sulfur atom of the sulfonamide. Specific examples of the alkyl group include the specific examples described above. Can be mentioned.
[0049]
Specific examples of the arylsulfonamide group may be those in which an aryl group that may have a direct substituent is bonded to the sulfur atom of the sulfonamide, and specific examples of the aryl group include the specific examples described above. Can be mentioned.
[0050]
Specific examples of the metal atom include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, etc., manganese, cobalt, Nickel and copper azo metal chelate compounds have excellent optical properties as optical recording materials.
[0051]
In the optical recording medium of the present invention, it is preferable to use a laser beam having a wavelength of 600 to 720 nm for the recording / reproducing wavelength. From the optical characteristics at this wavelength, among the squarylium compounds, the general formula (II) or the general formula (V) The compounds represented are preferred.
[0052]
Next, the definition of group in general formula (II)-(V) is demonstrated.
In the definitions of the groups of the general formulas (II) to (V), the alkyl moiety in the alkyl group and alkoxy group is a linear or branched alkyl group having 1 to 6 carbon atoms or a cyclic alkyl group having 3 to 8 carbon atoms. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, 1-methylbutyl group, 2-methylbutyl group, Examples thereof include a tert-pentyl group, a hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
[0053]
As an aryl part of an aryl group and an aralkyl group, a phenyl group, a naphthyl group, an anthryl group etc. are mentioned, for example.
[0054]
Examples of the aralkyl group include an aralkyl group having 7 to 15 carbon atoms such as a benzyl group, a phenethyl group, a phenylpropyl group, a naphthylmethyl group, and a benzhydryl group.
[0055]
Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
[0056]
A heterocycle in a heterocycle group, and R ₁₃ And R ₁₄ Or R ₁₇ And R ₁₈ Examples of the heterocyclic ring formed by combining together with two (two) carbon atoms include an aromatic heterocyclic ring and an alicyclic heterocyclic ring.
[0057]
Examples of the aromatic heterocycle include a 5-membered or 6-membered monocyclic aromatic heterocycle containing at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom, and a condensed 2- to 8-membered ring. And a condensed aromatic heterocycle having at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and more specifically, a pyridine ring, a pyrazine ring, a pyrimidine ring, Pyridazine ring, quinoline ring, isoquinoline ring, phthalazine ring, quinazoline ring, quinoxaline ring, naphthyridine ring, cinnoline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiophene ring, furan ring, thiazole ring, oxazole ring , Indole ring, isoindole ring, indazole ring, benzimidazole ring, benzotriazole ring, Zochiazoru ring, benzoxazole ring, purine ring, carbazole ring.
[0058]
As the alicyclic heterocycle, for example, a 5- or 6-membered monocyclic alicyclic heterocycle containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and a 3- to 8-membered ring are condensed. A bicyclic or tricyclic condensed alicyclic heterocyclic ring containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and more specifically, a pyrrolidine ring, a piperidine ring, Examples include piperazine ring, morpholine ring, thiomorpholine ring, homopiperidine ring, homopiperazine ring, tetrahydropyridine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydrofuran ring, tetrahydropyran ring, dihydrobenzofuran ring, tetrahydrocarbazole ring and the like.
[0059]
R ₁ And R ₂ Or R _Four And R _Five A heterocycle formed together with adjacent nitrogen atoms, and R _Four And R ₆ Or R _Five And R ₇ Examples of the heterocyclic ring formed together with the adjacent N—C—C include an aromatic heterocyclic ring containing a nitrogen atom and an alicyclic heterocyclic ring containing a nitrogen atom.
[0060]
Examples of the aromatic heterocycle containing a nitrogen atom include a 5-membered or 6-membered monocyclic aromatic heterocycle containing at least one nitrogen atom, a bicyclic or tricyclic nitrogen condensed with a 3- to 8-membered ring, and nitrogen. Examples thereof include condensed aromatic heterocycles containing at least one atom, and more specifically, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, quinoline ring, isoquinoline ring, phthalazine ring, quinazoline ring, quinoxaline ring. Naphthylidine ring, cinnoline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, indole ring, isoindole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzothiazole ring, Examples thereof include a benzoxazole ring, a purine ring, and a carbazole ring.
[0061]
Examples of the alicyclic heterocycle containing a nitrogen atom include, for example, a 5-membered or 6-membered monocyclic alicyclic heterocycle containing at least one nitrogen atom, and at least one nitrogen atom fused with a 3- to 8-membered ring. And more specifically, pyrrolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, homopiperidine ring, homopiperazine ring, tetrahydropyridine ring, tetrahydroquinoline ring. , Tetrahydroisoquinoline ring, tetrahydrocarbazole ring and the like.
[0062]
R ₁₃ And R ₁₄ Or R ₁₇ And R ₁₈ Examples of the alicyclic hydrocarbon ring formed together with adjacent (two) carbon atoms include those having 3 to 8 carbon atoms, which may be saturated or unsaturated. Examples thereof include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a cyclopentene ring, a 1,3-cyclopentadiene ring, a cyclohexene ring, and a cyclohexadiene ring.
[0063]
R ₁₃ And R ₁₄ Examples of the aromatic ring formed together with two adjacent carbon atoms include those having 6 to 14 carbon atoms, such as a benzene ring, a naphthalene ring, and an anthracene ring.
[0064]
An aryl group, an aralkyl group, a heterocyclic group, an aromatic ring, a heterocyclic ring containing a nitrogen atom or a substituent of the heterocyclic ring may be the same or different and have 1 to 5 substituents, preferably 1 to 5 substituents, for example, , Hydroxyl group, carboxyl group, nitro group, alkoxy group, alkyl group, aralkyl group, cyano group, halogen atom, -N = N-Ar (Ar is substituted with a hydroxyl group, carboxyl group, nitro group, alkoxy group, or halogen atom) An alkyl group that may be substituted, or an aryl group that may be substituted with a substituent such as a cyano group or a halogen atom.), —CH═CH—Ar (Ar is as defined above) and the like. Can be mentioned. Examples of the alkyl group, alkoxy group, aralkyl group, aryl group and halogen atom are the same as those described above.
[0065]
The substituent for the alkyl group or alkoxy group may be the same or different and may be 1-substitutable number, preferably 1 to 3 substituents such as hydroxyl group, carboxyl group, nitro group, alkoxy group, aryl group, halogen atom, etc. Is mentioned. Examples of the alkoxy group, aralkyl group, aryl group and halogen atom are the same as those described above.
[0066]
Examples of the substituent of the amino group are the same or different and include 1 to 2 substituents such as an alkyl group and an aryl group. Examples of the alkyl group and aryl group are the same as those described above.
[0067]
Hereinafter, the method for producing the squarylium compound used in the present invention will be described by taking the compounds represented by the general formulas (II) and (V) as examples. Hereinafter, the compound represented by the general formula (II) or (V) may be expressed as the compound (II) or the compound (V), respectively. The same applies to the compounds of other formula numbers.
[0068]
Reaction formula (1-a)
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[0069]
Reaction formula (1-b)
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[0070]
Reaction formula (1-c)
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[0071]
Reaction formula (2-a)
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[0072]
Reaction formula (2-b)
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[0073]
Reaction formula (2-c)
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Compound (G) + R _Three -H (B) → Compound (II)
[0074]
[Wherein R ₁ , R ₂ And R _Three Are as defined above, and Y is a halogen atom such as chlorine or bromine, or OR. _{twenty one} (Wherein R _{twenty one} Represents an alkyl group. R _{twenty one} Examples of the alkyl group in the definition include those similar to the alkyl groups in the general formulas (II) to (V). ). ]
[0075]
Reaction formula (1-a)
Compound (C) comprises compound (A) and 0.4 to 2 moles of compound (B), if necessary, in the presence of 0.4 to 2 moles of a base in a solvent at room temperature for 1 to 4 hours. It is obtained by reacting.
Examples of the solvent include chloroform, dichloromethane, 1,2-dichloroethane, ethyl acetate, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, toluene, benzene, dimethylformamide, dimethyl sulfoxide and the like.
Examples of the base include organic bases such as quinoline, triethylamine and pyridine, and inorganic bases such as potassium hydrogen carbonate and sodium hydrogen carbonate.
[0076]
Reaction formula (1-b)
Compound (D) is compound (C) in 50 to 90 volume / weight% acetic acid aqueous solution at 90 to 110 ° C. for 1 to 7 hours, or 50 to 99 wt% trifluoroacetic acid aqueous solution or concentrated sulfuric acid. It is obtained by reacting at 40 to 60 ° C. for 1 to 3 hours.
[0077]
Reaction formula (1-c)
Compound (II) comprises compound (D) and 0.5 to 2 moles of compound (E), if necessary, in the presence of 1.0 to 2.0 moles of base at 80 to 120 ° C. It is obtained by reacting for ˜15 hours.
As the solvent, for example, only an alcohol solvent having 2 to 8 carbon atoms such as ethanol, propanol, isopropanol, butanol, octanol, or a mixed solvent of the alcohol solvent and benzene or toluene (alcohol 50 vol / vol% or more) Etc. are used.
As the base, for example, an organic base such as quinoline, triethylamine, pyridine, or an inorganic base such as potassium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, or the like is used.
[0078]
Reaction formula (2-a)
Compound (F) can be obtained by the same operation as in the above reaction formula (1-a) except that compound (E) is used instead of compound (B).
[0079]
Reaction formula (2-b)
Compound (G) can be obtained by the same operation as in the above reaction formula (1-b) except that compound (F) is used in place of compound (C).
[0080]
Reaction formula (2-c)
Compound (II) is operated in the same manner as in the above reaction formula (1-c) except that compound (G) is used instead of compound (D) and compound (B) is used instead of compound (E). Can be obtained.
[0081]
After the reaction, for example, the compound (II) is further purified by a method usually used in organic synthetic chemistry (column chromatography, recrystallization or washing with a solvent, etc.), if necessary, by evaporating or filtering the solvent. Is isolated and purified.
[0082]
Reaction formula (3-a)
Embedded image
[0083]
Reaction formula (3-b)
Embedded image
[0084]
Reaction formula (3-c)
Embedded image
[0085]
Reaction formula (4-a)
Embedded image
[0086]
Reaction formula (4-b)
Embedded image
[0087]
Reaction formula (4-c)
Embedded image
Compound (P) + Compound (Ha) or Compound (Hb) → Compound (V)
[0088]
[Where Q ₂ , R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ , R ₁₉ , R ₂₀ And n are as defined above, X represents a halogen atom such as chlorine, bromine or iodine, or a tosyl group or mesyl group, and Y has the same meaning as described above. ]
[0089]
Reaction formula (3-a)
Compound (J) comprises compound (A) and 1 to 2 moles of compound (Ha) or (Hb), optionally in the presence of 1 to 2 moles of a base, in a solvent at 0 ° C. to room temperature. It is obtained by reacting for min to 70 hours.
Examples of the solvent include chloroform, dichloromethane, 1,2-dichloroethane, ethyl acetate, diethyl ether, methyl tert-butyl ether, tetrahydrofuran, toluene, benzene, dimethylformamide, dimethyl sulfoxide and the like.
Examples of the base include organic bases such as quinoline, triethylamine and pyridine, and inorganic bases such as potassium hydrogen carbonate and sodium hydrogen carbonate.
[0090]
Reaction formula (3-b)
Compound (K) is compound (J) in a 50 to 90 volume / volume% acetic acid aqueous solution at 90 to 110 ° C. for 1 to 7 hours, or in a 50 to 99 wt% trifluoroacetic acid aqueous solution. It is obtained by reacting at 50 ° C. for 1 to 3 hours.
[0091]
Reaction formula (3-c)
Compound (V) comprises compound (K) and 0.5 to 2 moles of compound (L) in the presence of 0.5 to 2 moles of a base in the presence of a solvent at 80 to 120 ° C. For 1 to 15 hours.
As the solvent, for example, only an alcohol solvent having 2 to 8 carbon atoms such as ethanol, propanol, isopropanol, butanol, octanol, or a mixed solvent of the alcohol solvent and benzene or toluene (alcohol 50 vol / vol% or more) Etc. are used.
As the base, for example, an organic base such as quinoline, triethylamine, pyridine, or an inorganic base such as potassium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, or the like is used.
[0092]
Reaction formula (4-a)
Compound (M) can be obtained by the same procedure as in the above reaction formula (3-a) except that compound (L) is used in place of compound (Ha) or (Hb).
[0093]
Reaction formula (4-b)
Compound (P) can be obtained by the same operation as in the above reaction formula (3-b) except that compound (M) is used instead of compound (J).
[0094]
Reaction formula (4-c)
Compound (V) is the same as that in the above reaction formula (3-c) except that compound (P) is used instead of compound (K), and compound (Ha) or compound (Hb) is used instead of compound (L). It can be obtained by performing the same operation.
[0095]
After the reaction, for example, the compound (V) is further purified by a method usually used in organic synthetic chemistry (column chromatography, recrystallization or washing with a solvent, etc.), if necessary, by evaporating or filtering the solvent. Is isolated and purified.
[0096]
Next, optical characteristics are raised as items necessary for constituting the recording layer of the optical recording medium of the present invention.
As conditions necessary for the optical characteristics, it is preferable that the recording / reproducing wavelength has a large absorption band on the short wavelength side from 630 nm to 670 nm, and the recording / reproducing wavelength is in the vicinity of the long wavelength end of the absorption band. This means that it is preferable to have a large refractive index and extinction coefficient at a recording / reproducing wavelength of 630 nm to 670 nm.
[0097]
Specifically, the refractive index n of the recording layer single layer with respect to light in the wavelength region of the recording / reproducing wavelength ± 5 nm is 1.5 or more and 3.0 or less, and the extinction coefficient k is 0.02 or more and 0.3 or less. It is preferable to be in the range. When n is 1.5 or more, a sufficient optical change is obtained, which is preferable because the recording modulation degree is high. When n is 3.0 or less, the wavelength dependency is not high, and recording is performed. Even in the reproduction wavelength region, it is preferable that errors do not occur. Further, when k is 0.02 or more, it is preferable because the recording sensitivity is improved, and when k is 0.3 or less, it is preferable to easily obtain a reflectance of 50% or more.
[0098]
The substrate usually has guide grooves with a depth of 1000 to 2500 mm. The track pitch is usually 0.7 to 1.0 [mu] m, but 0.7 to 0.8 [mu] m is preferable for high capacity use. The groove width is preferably a full width at half maximum of 0.18 to 0.40 μm. A thickness of 0.18 μm or more is preferable because a sufficient tracking error signal intensity can be easily obtained. Further, when the thickness is 0.40 μm or less, it is preferable that the recording portion does not spread laterally when recording.
[0099]
Next, the configuration of the recording medium of the present invention will be described.
FIG. 1 is a diagram showing an example of a layer structure applicable to the recording medium of the present invention, which is an example of a write-once type optical disc. A recording layer 2 is provided on the substrate 1 via an undercoat layer 3 as necessary, and a protective layer 4 is further provided as necessary. Further, a hard coat layer 5 can be provided under the substrate 1 as necessary.
[0100]
FIG. 2 is a diagram showing another example of a layer structure applicable to the recording medium of the present invention, which is an example of CD-R media. A reflective layer 6 is provided on the recording layer 2 having the configuration shown in FIG.
[0101]
FIG. 3 is a diagram showing a layer configuration example of another type (for DVD-R) that can be applied to the recording medium of the present invention. In this case, an adhesive layer 8 and a protective layer are formed on the protective layer 4 having the configuration of FIG. A substrate 7 is provided.
[0102]
That is, the recording medium of the present invention can have an air sandwich structure in which the recording layer (organic thin film layer) having the configuration shown in FIGS. 1 and 2 is placed inside and sealed with another substrate through a space. Moreover, it can also be set as the bonding structure adhere | attached through the protective layer.
[0103]
As a configuration of the recording medium when the recording medium of the present invention is applied to a DVD-R, a first substrate and a second substrate (hereinafter sometimes referred to as a first substrate and a second substrate) are used as a recording layer. The basic structure is a structure bonded with an adhesive via The recording layer may be a single organic dye layer or a laminate of an organic dye layer and a metal reflective layer to enhance the reflective layer. The recording layer and the substrate may be formed through an undercoat layer or a protective layer, or may be laminated to improve the function. The most commonly used is the first substrate / organic dye layer / metal reflective layer / protective layer / adhesive layer / second substrate structure.
[0104]
<Board>
The necessary characteristics of the substrate must be transparent to the laser beam used only when recording / reproduction is performed from the substrate side, and the substrate does not need to be transparent when recording / reproduction is performed from the recording layer side. Therefore, in the present invention, when two substrates are used in a sandwich shape, for example, if only one substrate (second substrate) is transparent, the other substrate (first substrate) may be transparent or opaque. .
[0105]
As the substrate material, for example, plastic such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic, or metal can be used.
[0106]
If only one layer is used, a tracking guide groove or guide pit, and an address signal, etc. are recorded on the surface of the substrate. A format may be formed.
[0107]
<Recording layer>
The recording layer generates an optical change by irradiation with laser light, and information can be recorded by the change. In the recording layer, the dye mixture [squarylium compound and compound (I )), And the recording layer may be formed using the dyes characterized in the present invention one by one or in combination. Furthermore, in addition to the above-mentioned dyes that are the characteristics of the present invention, they may be mixed or laminated with other organic dyes for the purpose of improving optical characteristics, recording sensitivity, signal characteristics, and the like.
[0108]
Examples of such other organic dyes include polymethine dyes, naphthalocyanine, phthalocyanine, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, Tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based dyes, metal chelate compounds, and the like can be mentioned. These pigments may be used alone or in combination of two or more.
[0109]
In the dye, metal, metal compound, for example, In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, Cd, etc. can be used in the form of dispersion or lamination. Further, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or silane coupling agent may be dispersed and mixed in the dye. Alternatively, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, and the like can be used together for the purpose of improving characteristics.
[0110]
The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD or solution coating. When using a coating method, the above-mentioned dye or the like is dissolved in an organic solvent or the like, and a conventional coating method such as spraying, roller coating, dipping, or spin coating is used.
[0111]
Generally used organic solvents include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and sulfoxides such as dimethyl sulfoxide. , Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane, Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene, cellosolves such as methoxyethanol and ethoxyethanol, hexane, pentane and cyclohexane Hydrocarbons such as methylcyclohexane, and the like.
[0112]
The thickness of the recording layer is preferably 100 to 10 μm, more preferably 200 to 2000 μm.
[0113]
<Underlayer>
The undercoat layer comprises (a) improved adhesion, (b) a barrier such as water or gas, (c) improved storage stability of the recording layer, (d) improved reflectance, (e) a substrate from a solvent, It is used for the purpose of protecting the recording layer, (f) forming guide grooves, guide pits, preformats, and the like.
[0114]
For the purpose of (a), polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers and various other polymer substances, and silane coupling agents are used. For the purposes of (b) and (c), in addition to the polymer material, an inorganic compound such as SiO ₂ , MgF ₂ , SiO, TiO ₂ ZnO, TiN, SiN, and the like, and metals or semimetals such as Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, and Al can be used. For the purpose of (d), metals such as Al and Ag, and organic thin films having a metallic luster such as methine dyes and xanthene dyes can be used. For the purposes of (e) and (f) In contrast, an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.
[0115]
The thickness of the undercoat layer is preferably 0.01 to 30 μm, more preferably 0.05 to 10 μm.
[0116]
<Metal reflective layer>
Examples of the material for the metal reflective layer include metals that are high in reflectance and are not easily corroded, metalloids, and specific examples thereof include Au, Ag, Cr, Ni, Al, Fe, Sn, Cu, and the like. However, Au, Ag, Al, and Cu are most preferable from the viewpoint of reflectance and productivity, and these metals and metalloids may be used alone or in combination of two or more.
[0117]
Examples of the method for forming the metal reflective layer include vapor deposition and sputtering, and the film thickness is preferably 50 to 5000 mm, more preferably 100 to 3000 mm.
[0118]
<Protective layer, substrate surface hard coat layer>
The protective layer or substrate surface hard coat layer (a) protects the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., (b) improves the storage stability of the recording layer (reflection / absorption layer), (c ) Used for the purpose of improving the reflectance. For these purposes, the materials shown in the undercoat layer can be used. Also, inorganic materials such as SiO and SiO ₂ Can also be used as organic materials such as polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, natural rubber, styrene butadiene resin, chloroprene rubber Also, heat softening, heat melting resins, and ultraviolet curable resins such as waxes, alkyd resins, drying oils, and rosins can be used. Among these materials, the most preferable example of the protective layer or the substrate surface hard coat layer is an ultraviolet curable resin excellent in productivity.
[0119]
The film thickness of the protective layer or the substrate surface hard coat layer is preferably 0.01 to 30 μm, more preferably 0.05 to 10 μm.
[0120]
In the present invention, the undercoat layer, the protective layer, and the substrate surface hard coat layer are the same as in the recording layer, such as a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, and a plasticizer. Etc. can be contained.
[0121]
<Protection board>
When the protective substrate is irradiated with laser light from the protective substrate side, it must be transparent to the laser beam used, and when used as a simple protective plate, transparency is not an issue. The substrate material that can be used is exactly the same as the above-mentioned substrate material, and plastic, such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic, or metal is used. be able to.
[0122]
<Adhesive, adhesive layer>
Any material can be used as long as it can bond two recording media, and in view of productivity, an ultraviolet curable adhesive or a hot melt adhesive is preferable.
[0123]
【Example】
Examples of the present invention and comparative examples are shown below. The evaluation results of the optical recording media obtained in these examples and comparative examples are shown in Table 1 below. In addition, the compound example used by an Example and a comparative example is a thing of the following Tables 2-6.
[0124]
(Example 1)
A mixture of compound examples A-3 and B-4 on a 0.6 mm thick injection-molded polycarbonate substrate having guide grooves with a groove depth of 1700 mm, a half width of 0.23 μm and a track pitch of 0.74 μm 1) is dissolved in 2,2,3,3-tetrafluoropropanol, and the solution is spinner coated to form an organic dye layer having a thickness of 900 mm, and then a reflective layer of silver 1300 mm is provided by sputtering. A protective layer of 6 μm was provided on the top with an acrylic photopolymer. Further, an injection molded polycarbonate substrate having a thickness of 0.6 mm was bonded with an acrylic photopolymer to obtain an optical recording medium.
[0125]
(Examples 2 to 10)
Using the combination of dyes shown in Table 1, an optical recording medium was formed in exactly the same manner as in Example 1.
[0126]
(Comparative Example 1)
Using only the squarylium compound B-1, an optical recording medium was formed in exactly the same manner as in Example 1.
[0127]
<Recording conditions>
A semiconductor laser beam having an oscillation wavelength of 658 nm and a beam diameter of 1.0 μm is recorded on this optical recording medium, and an EFM signal (linear velocity of 3.5 m / second) is recorded while tracking. The reproduction waveform was observed with a power of 0.7 mW.
[0128]
<Weather resistance test conditions>
Light resistance test: 40,000 Lux, Xe light, 10 hours continuous irradiation
Storage test: 50 ° C, 80%, left for 600 hours
[0129]
[Table 1]
[0130]
[Table 2]
[0131]
[Table 3]
[0132]
[Table 4]
[0133]
[Table 5]
[0134]
[Table 6]
In Tables 2 to 6, Me is methyl, Et is ethyl, ⁿ Bu represents n-butyl, and Ph represents phenyl.
[0135]
【The invention's effect】
1) Claims 1 to 4 and 8
An optical recording medium which can be recorded and reproduced with a laser beam having a wavelength region of 670 nm or less and has excellent light resistance and storage stability can be provided. In particular, it has become possible to provide an optical recording medium having excellent light resistance as compared with the case where a squarylium compound is used alone.
2) Claims 5-6
In addition to the first effect, it is possible to provide an optical recording medium capable of recording / reproducing with a stable high reflectivity and high modulation degree.
3) Claim 7
In addition to the first effect, an optical recording medium capable of stable recording and reproduction can be provided.
4) Claim 9
An optical recording method capable of producing the first effect can be provided.
[Brief description of the drawings]
FIGS. 1A to 1D are schematic cross-sectional views showing the configuration of a normal write-once optical recording medium that can be applied to the recording medium of the present invention.
FIGS. 2A to 2C are schematic cross-sectional views showing the configuration of a high reflectance type (for CD-R) optical recording medium that can be applied to the recording medium of the present invention.
FIGS. 3A to 3C are schematic cross-sectional views showing the configuration of a large-capacity reflectance (for DVD-R) optical recording medium that can be applied to the recording medium of the present invention.
[Explanation of symbols]
1 Substrate
2 Recording layer (organic dye layer)
3 Underlayer
4 Protective layer
5 Hard coat layer
6 Metal reflective layer
7 Protection board
8 Adhesive layer

Claims (7)

In an optical recording medium having a recording layer provided on a substrate, a squarylium compound represented by the following general formula (II) or (V) in the recording layer and the following general formula (I)
[In the formula, A represents an aromatic ring of 6 atoms not containing N, and B has an aromatic ring or a substituent which may have a substituent together with the carbon atom to which it is bonded. And X represents a substituent having an active hydrogen group] and an azo metal chelate compound composed of a metal. A characteristic optical recording medium.
[Wherein, R ₁ and R ₂ are the same or different and have a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Represents an aryl group which may be substituted. R ₁ and R ₂ may be combined with an adjacent nitrogen atom to form a heterocyclic ring which may have a substituent. R ₃ represents the following general formula (III) or (IV):]
[Wherein, R ₄ and R ₅ are the same or different and each represents a hydrogen atom or an alkyl group, or R ₄ and R ₅ may have a substituent together with an adjacent nitrogen atom. Forming a heterocyclic ring, and R ₆ , R ₇ , R ₈ and R ₉ are the same or different and are a hydrogen atom, an alkyl group which may have a substituent, or an alkoxy which may have a substituent. Represents a group, a hydroxyl group, or a halogen atom, and R ₄ and R ₆ , or R ₅ and R ₇ together with adjacent N—C—C may form a heterocyclic ring containing a nitrogen atom, The heterocyclic ring may have a substituent. However, R ₆ , R ₇ , R ₈ and R ₉ are not all hydrogen atoms. ]
[Wherein, Q ₁ represents a carbon atom or a nitrogen atom, and R ₁₀ and R ₁₁ may be the same or different and each may have a hydrogen atom, an alkyl group which may have a substituent, or a substituent. Represents a good aryl group, an aralkyl group which may have a substituent, or a hydroxyl group (provided that when Q ₁ is a nitrogen atom, R ₁₁ does not exist), and R ₁₂ has a hydrogen atom or a substituent. Represents an optionally substituted alkyl group, an optionally substituted aryl group or an optionally substituted aralkyl group, and R ₁₃ and R ₁₄ are the same or different and represent a hydrogen atom, a substituent, Represents an optionally substituted alkyl group, an alkoxy group or a halogen atom, or R ₁₃ and R ₁₄ together with two adjacent carbon atoms have an alicyclic hydrocarbon ring and a substituent. It may have an aromatic ring or substituent To form a good heterocycle. ]
[Wherein Q ₂ represents a carbon atom or a nitrogen atom, and R ₁₅ has a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent or a substituent. R ₁₆ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aralkyl group that may be substituted, an aryl group that may have a substituent, an amino group that may have a substituent, or a heterocyclic group that may have a substituent. R ₁₇ and R ₁₈ are the same or different and each represents an optionally substituted alkyl group, or R ₁₇ and R ₁₈ together with an adjacent carbon atom represent an alicyclic hydrocarbon ring or A heterocycle may be formed. However, when Q ₂ is a nitrogen atom, R ₁₈ does not exist. R ₁₉ represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent, R ₂₀ represents a halogen atom, An alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a trifluoromethyl group, a nitro group, a cyano group, or a substituent Represents an alkoxy group which may have n represents an integer of 0 to 4, wherein when n is 2 to 4, R ₂₀ may be the same or different, and two adjacent R ₂₀ together with two adjacent carbon atoms May form an aromatic ring which may have a substituent]   2. The optical recording medium according to claim 1, wherein the squarylium compound and the azo metal chelate compound are in a weight ratio of 90:10 to 20:80.   3. The optical recording medium according to claim 1, wherein the metal atom of the azo metal chelate compound is at least one selected from the group consisting of manganese, cobalt, nickel and copper.   The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ k ≦ 0.3 with respect to light having a recording / reproducing wavelength of ± 5 nm. The optical recording medium according to claim 1.   The optical recording medium according to claim 1, further comprising a reflective layer, wherein the reflective layer is gold, silver, copper, aluminum, or an alloy of these metals.   6. The optical recording according to claim 1, wherein a track pitch on the substrate is 0.7 to 0.8 [mu] m, and a groove width is a half value width of 0.18 to 0.40 [mu] m. Medium. 7. An optical recording method for recording on the optical recording medium according to claim 1 at a recording wavelength of 600 to 720 nm.