JP2002370453A - Optical recording medium, optical recording method and optical recording device employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording material in an optical recording medium appli cable to an additional write type DVD system employing a semiconductor laser having an oscillating wavelength shorter than ever, the optical recording medium excellent in light resistance and storage stability especially when a squalilum compound is employed, and also to provide an optical recording method and an optical recording device employing thereof. SOLUTION: In the optical recording medium formed by providing a recording layer on a board, the recording layer includes at least each one kind of a squalilum metal chelate compound consisting of a squalilum compound and a metal, and of an azo metal chelate compound consisting of an azo compound represented by general formula I and a metal, wherein A represents a residue forming a heterocycle together with a carbon atom and a nitrogen atom combined therewith and being allowable to have a substituent, B represents a residue forming an aromatic cycle or a heterocycle together with two carbon atoms combined therewith and being allowable to have a substituent, and X represents a substituent having an active hydrogen group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly, to irradiating a light beam to cause an optical change in the transmittance and the reflectance of a recording material.
The present invention relates to an optical recording medium on which information can be recorded, reproduced, and additionally recorded.

[0002]

2. Description of the Related Art a. Conventional technology for write-once optical recording media (for information recording)

(1) Using a cyanine dye as a recording material JP-A-57-82093, JP-A-58-56892, JP-A-58-112790, JP-A-58-114989,
JP-A-59-85791, JP-A-60-83236, JP-A-60-89842, JP-A-61-25886

(2) Using a phthalocyanine dye as a recording material JP-A-61-150243, JP-A-61-17728
7, JP-A-61-154888, JP-A-61-2460
91, JP-A-62-39286, JP-A-63-3799
1, JP-A-63-39888

B. Conventional technology of write-once compact disc

(1) Using a cyanine dye / metal reflective layer as a recording material JP-A-1-159842, JP-A-2-42652, JP-A-2-13656, JP-A-2-168446

(2) Using a phthalocyanine dye (azaannulene dye) as a recording material JP-A-1-176585, JP-A-3-215466, JP-A-4-113886, JP-A-4-226390, JP-A-5-1272, Japanese Unexamined Patent Application Publication No. Hei.
116456, JP-A-7-268227, JP-A-7-3
14897

(3) Using an azo metal chelate dye as a recording material JP-A-4-46186, JP-A-4-141489, JP-A-4-36088, JP-A-5-279580, JP-A-7-51673, and JP-A-7-51673 -161069, JP-A-7-
37272, JP-A-7-71867, JP-A-8-231
866, JP-A-8-295811

C. Large capacity write-once compact disc (D
VD-R)

(1) Using Cyanine Dye / Metal Reflective Layer as Recording Material PIONEER R & D vol. 6 No. Two, one
996: Development of DVD-Recordable, DVD
Basic development of -R dye disk ISOM / ODS'96, 1996: High de
nsity of recording on Dye
material Disc approach f
or 4.7G

(2) Using a polymethine dye as a recording material JP-A-10-83577, JP-A-10-119434,
JP-A-10-149584, JP-A-10-18833
9, JP-A-10-278426

(3) Using a polymethine dye / light stabilizer as a recording material JP-A-10-109475, JP-A-10-10947
6, JP-A-10-134413, JP-A-10-1667
39

(4) Using an azo metal chelate dye / metal reflective layer as a recording material Japanese Patent Publication No. 5-67438, JP-A-7-161069, JP-A-8-156408, JP-A-8-231866, JP-A-8-332772. JP-A-9-58123, JP-A-9-58123
175031, JP-A-9-193545, JP-A-9-2
74732, JP-A-9-277703, JP-A-10-6
644, JP-A-10-6650, JP-A-10-665
1, JP-A-10-36693, JP-A-10-4460
6, JP-A-10-58828, JP-A-10-8651
9, JP-A-10-149584, JP-A-10-1572
93, JP-A-10-157300, JP-A-10-157
301, JP-A-10-157302, JP-A-10-18
1199, JP-A-10-181201, JP-A-10-1
81203, JP-A-10-181206, JP-A-10-
188340, JP-A-10-188341, JP-A-10-188
188358, JP-A-10-208303, JP-A-1
0-214423, JP-A-10-228671, JP-A-11-12483

(5) Using a tetraazaporphyrin (porphyrazine) dye / metal reflective layer as a recording material JP-A-9-267562, JP-A-9-309268, JP-A-10-856

(6) Using other dye / metal reflective layer as a recording material JP-A-10-86517, JP-A-10-93788, JP-A-10-226172, JP-A-10-244758,
JP-A-10-287819, JP-A-10-29710
3, JP-A-10-309871, JP-A-10-3098
72

(7) Using a cyanine dye / azo metal chelate dye (salt-forming dye) / metal reflective layer as a recording material JP-B-7-51682, JP-A-11-34499, WO
98/29257, JP-A-9-323478, JP-A-1
1-195242, JP-A-11-250505, JP-A-2
000-168237, JP-A-2000-190641,
JP-A-2000-190642, JP-A-2000-1982
73

(8) Formazan (metal chelate) dye /
JP-A-2791944, JP-A-8-295079, JP-A-9-95520, JP-A-9-193546, JP-A-10-337958

(9) Dipyrromethene (metal chelate) dye / using other dyes as recording materials JP-A-10-162430, JP-A-10-16673
2, JP-A-10-226172, JP-A-11-4285
8, JP-A-11-92682, JP-A-11-16546
5, JP-A-11-208111, JP-A-11-2273
32, JP-A-11-227333, JP-A-11-255
774, JP-A-11-256057

As seen above, many optical recording media have been proposed, and DVD-Rs are currently being developed as next-generation large-capacity optical disks. As elemental technologies for improving the recording capacity, it is necessary to develop recording materials for miniaturizing recording pits, adopt image compression technology represented by MPEG2, and shorten the wavelength of semiconductor laser for reading recording pits. It is.

Heretofore, as a semiconductor laser in the red wavelength region, 670 nm band Al has been used for bar code readers and measuring instruments.
Although only GaInP laser diodes have been commercialized, red lasers are being used in the optical storage market in earnest as the density of optical disks increases.

In the case of a DVD drive, 635 is used as a light source.
It is standardized at two wavelengths, a laser diode in the nm band and a laser diode in the 650 nm band. On the other hand, a read-only DVD-ROM
The drive is commercialized at a wavelength of about 650 nm. Under these circumstances, the most preferable DVD-R medium is a medium capable of recording and reproducing at a wavelength of 630 to 690 nm. A squarylium compound is one of the recording layers of an optical recording medium for recording and reproducing with an optical pickup using a laser having a wavelength of 630 to 690 nm. However, such a compound has poor light stability for use in an optical recording medium. An azo metal chelate compound is exemplified as a dye having high light resistance. However, when this dye is used alone, there has been a problem that a sufficient reflectance cannot be obtained.

[0022]

According to the present invention, a recording material, particularly a squarylium compound, in an optical recording medium applicable to a write-once DVD system using a semiconductor laser having an oscillation wavelength shorter than that of the conventional system is used. An object of the present invention is to provide an optical recording medium having excellent light resistance and storage stability when used, an optical recording method and an optical recording apparatus using the optical recording medium.

[0023]

As a result of investigations by the present inventors, it has been found that the squarylium compound is chelated with a metal to increase the light stability, and further mixed with an azo metal chelate compound having high light resistance to further increase the light stability. It has been found that it has become possible to provide an optical recording medium having high light resistance and high storage stability, and by chelating a squarylium compound with a metal, the absorption coefficient of the squarylium compound can be improved, and high reliability and high reliability can be achieved. It has become possible to provide an optical recording medium having low reflectance and low jitter. That is, according to the present invention, an optical recording medium having high reliability and high reflectance can be provided.

A first aspect of the present invention relates to a basic structure and a material structure of the present invention. In an optical recording medium having at least a recording layer provided on a substrate, a squarylium metal chelate compound comprising a squarylium compound and a metal in the recording layer. And an azo metal chelate compound composed of a metal and an azo compound represented by the following general formula (I).

Embedded image (In the formula, A represents a residue which forms a heterocyclic ring which may have a substituent together with a carbon atom and a nitrogen atom to which it is bonded, and B represents a group to which it is bonded. Represents a residue forming an aromatic ring which may have a substituent or a heterocyclic ring which may have a substituent together with two carbon atoms, and X represents a substituent having an active hydrogen group .)

The second aspect of the present invention relates to limiting the preferable range of the mixing ratio between the squarylium metal chelate compound and the azo metal chelate compound.
0:80 in the first optical recording medium.

A third aspect of the present invention relates to an optimum metal species of the azo metal chelate compound, 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. In the first and second optical recording media.

The fourth aspect of the present invention relates to the basic structure of the squarylium metal chelate compound, wherein the squarylium metal chelate compound is a compound represented by the following general formula (II): In the medium.

Embedded image [Wherein, R ₁ and R ₂ are the same or different substituents, and are a hydrogen atom, an alkyl group which may have a substituent,
Represents an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. M ₁ represents a metal atom having coordination ability. Z is an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or Y = CH- (Y
Represents a heterocyclic group which may have a substituent).
m1 represents an integer of 2 or 3. ]

A fifth aspect of the present invention relates to an optimum structure of the squarylium metal chelate compound, wherein Z in the general formula (II) is the following general formula (II-II): It is in.

Embedded image [Wherein, R ₃ and R ₄ are the same or different and each represents an alkyl group which may have a substituent, or R ₃ and R ₄ together with an adjacent carbon atom form an alicyclic group; R ₅ may form a hydrocarbon ring or a heterocyclic ring,
Represents 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, and R ₆ represents a halogen atom or a substituent. An alkyl group which may be substituted, an aralkyl group which may have a substituent, an aryl group which may have a substituent,
Represents a nitro group, a cyano group or an optionally substituted alkoxy group, and n represents an integer of 0 to 4, wherein
When n is 2 to 4, R ₆ may be the same or different;
Further, two adjacent R ₆ may be combined with two adjacent carbon atoms to form an aromatic ring which may have a substituent. ]

A sixth aspect of the present invention relates to the limitation of the optimum metal type of the squarylium metal chelate compound, and the fourth to fifth optical recording media, wherein M ₁ is aluminum.

The seventh aspect of the present invention relates to the limitation of the optimum optical constant of the recording layer, and the refractive index n of the recording layer single layer with respect to light in the wavelength range of recording / reproducing wavelength ± 5 nm is 1.5 ≦ n ≦ 3.0. Wherein the extinction coefficient k satisfies 0.02 ≦ k ≦ 0.3.

An eighth aspect of the present invention relates to the limitation of an optimum material when a reflective layer is used, which has a reflective layer, and the reflective layer is made of gold,
The first to seventh optical recording media are characterized by containing silver, copper, aluminum or an alloy of these metals.

The ninth aspect of the present invention relates to the limitation of the optimum shape of the guide groove of the optical recording medium, wherein the track pitch on the substrate is 0.7 to 0.7.
The groove width is in the range of 0.8 μm and the half width is 0.18 to
In the range of 0.40 μm.
8 optical recording medium.

A tenth aspect of the present invention resides in the first to ninth optical recording media, wherein recording is possible at a wavelength of 600 to 720 nm.

An eleventh aspect of the present invention relates to an optical recording method characterized in that recording is performed on any one of the first to tenth optical recording media at a wavelength of 600 to 720 nm.

The twelfth aspect of the present invention relates to an optical recording apparatus equipped with any one of the first to tenth optical recording media.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present specification, a compound represented by the general formula (I) is referred to as a compound (I). The same applies to compounds with other formula numbers. An azo metal chelate compound comprising the compound (I) and a metal is referred to as an azo metal chelate compound (I).

First, the description of compound (I) will be made. The definition of the substituent in the general formula (I) is as described above.

Specific examples of A in the general formula (I) include a thiazole ring, a benzothiazole ring, an imidazole ring, a benzimidazole ring, a thiadiazole ring, an oxazole ring, a benzoxazole ring, a triazole ring, a pyrazole ring, and an oxadiazole ring. Residues forming an azole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a quinoline ring and the like can be mentioned. These nitrogen-containing heterocycles may have a substituent.

Specific examples of the substituent include a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxyl group, a carboxyl group, an amino group, a carbamoyl group, an alkyl group which may have a substituent, Aryl group which may have a substituent, heterocyclic residue which may have a substituent, alkoxy group which may have a substituent, 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,
An arylcarboxamide group which may have a substituent,
An alkylsulfonamide group which may have a substituent,
Alkyl carbamoyl group which may have a substituent, aryl carbamoyl group which may have a substituent, alkenyl group which may have a substituent, alkyl sulfa which may have a substituent Moyl groups and the like.

Examples of the alkyl group include those having 1 to 15 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group,
n-hexyl group, n-heptyl group, n-octyl group, n
-Nonyl group, linear alkyl group such as n-decyl group, 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-ethylpentyl group, 3-ethylpentyl group, 2-methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 2-ethylhexyl group, 3-ethylhexyl group Isopropyl group, sec-butyl group, 1-ethylpropyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1-methylheptyl group, 1-ethylbutyl group,
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-methylheptyl group, 1-ethylhexyl group,
1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl-2-methylbutyl group, 1-isopropyl-3-methylbutyl group, 1-methyloctyl group, 1-ethylheptyl group, 1-propylhexyl group,
1-isobutyl-3-methylbutyl group, neopentyl group, tert-butyl group, tert-hexyl group, te
branched alkyl groups such as rt-amyl group and tert-octyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- (2-ethylhexyl) cyclohexyl group, and bornyl And cycloalkyl groups such as an isobornyl group and an adamantyl group. Among them, those having 1 to 8 carbon atoms are preferable.

Further, these linear and branched alkyl groups may have a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, or a specific substituent (for example, a halogen atom or a nitro group. (It may be substituted.) It may be substituted by an aryl group, a heterocyclic residue or the like. Further, it may be substituted with the above-mentioned alkyl group via an atom such as oxygen, sulfur, or nitrogen.

Examples of the alkyl group substituted via oxygen include a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a butoxyethyl group, an ethoxyethoxyethyl group, a methoxypropyl group and an ethoxypropyl group. As the alkyl group substituted via sulfur, a methylthioethyl group, an ethylthioethyl group, an ethylthiopropyl group, and the like, and as the alkyl group substituted via nitrogen, a dimethylaminoethyl group,
Examples thereof include a diethylaminoethyl group and a diethylaminopropyl group.

Specific examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a fluorenyl group, a phenalenyl group, a phenanthranyl group, a triphenylenyl group, a pyrenyl group and the like. Further, these aryl groups include an alkyl group, a hydroxyl group, a halogen atom, a nitro group,
A carboxyl group, a cyano group, an aryl group which may have a specific substituent (for example, may be substituted with a halogen atom or a nitro group), a heterocyclic residue, or the like; It may be substituted with the above-mentioned alkyl group via an atom such as oxygen, sulfur, or nitrogen.

Specific examples of the heterocyclic residue include a furyl group,
Thienyl, pyrrolyl, benzofuranyl, isobenzofuranyl, benzothienyl, indolinyl, isoindolinyl, carbazolyl, pyridyl, piperidyl, quinolyl, isoquinolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl Groups, imidazolyl groups, pyrazolyl groups, benzimidazolyl groups, pyrazinyl groups, pyrimidinyl groups, pyridazinyl groups, quinoxalinyl groups and the like. Further, these heterocyclic residues may have a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, or a specific substituent (for example, may be substituted with a halogen atom or a nitro group). It may be substituted with an aryl group, a heterocyclic residue, or the like, or may be substituted with the above-mentioned alkyl group via an atom such as oxygen, sulfur, or nitrogen.

Specific examples of the halogen atom include fluorine,
Examples include atoms of chlorine, bromine, iodine and the like.

The alkoxy group which may have a substituent may be any as long as an alkyl group which may have a substituent is directly bonded to an oxygen atom. Examples include the specific examples described above.

The aryloxy group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to an oxygen atom. Specific examples include the specific examples described above.

The alkylthio group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to a sulfur atom. Examples include the specific examples described above.

The arylthio group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to a sulfur atom. Examples include the specific examples described above.

The alkylamino group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to the nitrogen atom. Specific examples include the specific examples described above. Further, alkyl groups are bonded to each other, piperidino group, morpholino group, pyrrolidinyl group, piperazinyl group,
A ring may be formed like an indolinyl group and an isoindolinyl group.

The arylamino group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to the nitrogen atom. Specific examples include the specific examples described above.

The alkoxycarbonyl group which may have a substituent may be any one in which an alkyl group which may have a substituent is directly bonded to an oxygen atom. Specific examples include the specific examples described above.

The aryloxycarbonyl group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to an oxygen atom.
Specific examples of the aryl group and the substituent include the specific examples described above.

The alkylcarboxamide group which may have a substituent may be any one in which an alkyl group which may have a substituent is directly bonded to a carbon atom. Specific examples include the specific examples described above.

The arylcarboxamide group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to a carbon atom. Specific examples include the specific examples described above.

The alkylsulfonamide group which may have a substituent may be any as long as an alkyl group which may have a substituent is directly bonded to a carbon atom. Specific examples include the specific examples described above.

The alkylcarbamoyl group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to the nitrogen atom. Specific examples include the specific examples described above. Further, the alkyl groups may be bonded to each other to form a ring like a piperidino group, a morpholino group, a pyrrolidinyl group, a piperazinyl group, an indolinyl group, an isoindolinyl group, and the like.

The arylcarbamoyl group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to the nitrogen atom. Specific examples include the specific examples described above.

Specific examples of the alkylsulfamoyl group include those in which an alkyl group which may have a substituent is directly bonded to the nitrogen atom of the sulfamoyl group. Specific examples of the alkyl group and the substituent Examples include the specific examples described above.

Specific examples of the alkenyl group include those having 2 carbon atoms.
6 to vinyl, allyl, 1-propenyl, methacrylic, crotyl, 1-butenyl, 3-
Butenyl group, 2-pentenyl group, 4-pentenyl group, 2
-Hexenyl group, 5-hexenyl group and the like. Examples of the substituent of the alkenyl group include the same as the above-mentioned substituent of the alkyl group.

Specific examples of B include a residue forming a benzene ring, a naphthalene ring, a pyridine ring, a quinoline ring and the like. These aromatic rings or hetero rings may have a substituent. Specific examples of the substituent include the same substituents as those of A described above.

Specific examples of the substituent having an active hydrogen group represented by 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 and an alkylcarbamoyl group. , An arylcarbamoyl group, a sulfo group, a sulfino group, a sulfeno group, a sulfamoyl group, and the like.

Specific examples of the alkylcarboxamide group, arylcarboxamide group, alkylcarbamoyl group and arylcarbamoyl group include the specific examples described above.

Specific examples of the alkylsulfonamide group which may have a substituent may be any as long as an alkyl group which may have a substituent is directly bonded to a sulfur atom. Specific examples of the group and the substituent include those described above.

Specific examples of the arylsulfonamide group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to a sulfur atom. Specific examples of the group and the substituent include those described above.

Specific examples of the metal atom which forms the azo metal chelate compound (I) together with the above compound (I) include aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, Examples include zinc, zirconium, niobium, molybdenum, ruthenium, rhodium, and palladium. Among them, manganese, cobalt,
Nickel, copper, aluminum and vanadium are preferred,
Furthermore, the azo metal chelate compounds (I) of manganese, cobalt, nickel and copper have excellent optical properties as optical recording materials.

The azo metal chelate compound (I) of the present invention has excellent optical properties among the azo metal chelate compounds, and can provide an optical recording medium having high reflectance by mixing with the squarylium metal chelate compound.

Among the squarylium metal chelate compounds, compound (II) is preferred. Next, the compound (II) will be described. The general formula (II) or (II-II)
In the definition of the substituent in the alkyl group and the alkyl moiety in the alkoxy group, a linear or branched alkyl group having 1 to 6 carbon atoms or a cyclic alkyl group having 3 to 8 carbon atoms, and the like. Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, 1-methylbutyl, 2-methylbutyl, tert-pentyl, hexyl Group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group and the like.

Examples of the aralkyl group include aralkyl groups having 7 to 15 carbon atoms, such as benzyl, phenethyl, phenylpropyl, and naphthylmethyl.

Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group and an azulenyl group.

Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom and an iodine atom.

The substituents on the aralkyl group, the aryl group, the alkoxy group, the aromatic ring or the heterocyclic group may be the same or different and may have 1 to 5 substituents, for example, a hydroxyl group, a carboxyl group, a halogen atom, an alkyl group, Examples include an alkoxy group, a nitro group, a trifluoromethyl group, and an amino group which may have a substituent. Examples of the halogen atom, the alkyl group and the alkoxy group include the same as those described above.

Examples of the substituent of the alkyl group include the same or different and one to three substituents such as a hydroxyl group, a carboxyl group, a halogen atom and an alkoxy group.
Examples of the halogen atom and the alkoxy group include the same as described above.

Examples of the substituent for the amino group include the same or different and one to two alkyl groups, and the alkyl group in this case is the same as described above.

The metal atom (M ₁ ) having a coordinating ability includes, for example, aluminum, zinc, copper, iron, nickel, chromium, cobalt, manganese, iridium, vanadium, titanium and the like. aluminum,
Copper, nickel, and cobalt are preferred, and aluminum is more preferred.

Examples of the aromatic ring formed by two adjacent R ₆ , together with two adjacent carbon atoms, include a benzene ring.

Other than the heterocyclic group represented by Y in the general formula (II)
A heterocyclic ring in the heterocyclic group, or R _ThreeAnd R_FourBut adjacent charcoal
Heterocycles formed together with elementary atoms include
Are selected from nitrogen, oxygen and sulfur
5- or 6-membered monocyclic aroma containing at least one atom
Heterocyclic or aliphatic heterocyclic, 3- to 8-membered fused ring
Or tricyclic, from nitrogen, oxygen and sulfur
A condensed aromatic containing at least one selected atom
Or an aliphatic heterocyclic ring, and more specifically,
Ring, pyrazine ring, pyrimidine ring, pyridazine ring, quino
Phosphorus ring, isoquinoline ring, phthalazine ring, quinazoline
Ring, quinoxaline ring, naphthyridine ring, cinnoline ring,
Pyrrole ring, pyrazole ring, imidazole ring, triazo
Ring, tetrazole ring, thiophene ring, furan ring,
Azole ring, oxazole ring, indole ring, isoyne
Doll ring, indazole ring, benzimidazole ring,
Benzotriazole ring, benzothiazole ring, benzooxy
Sazol ring, purine ring, carbazole ring, pyrrolidine
Ring, piperidine ring, piperazine ring, morpholine ring, thio
Morpholine ring, homopiperidine ring, homopiperazine ring,
Tetrahydropyridine ring, tetrahydroquinoline ring, t
Trahydroisoquinoline ring, tetrahydrofuran ring,
Trahydropyran ring, dihydrobenzofuran ring, tetra
Hydrocarbazole ring and the like can be mentioned.

Examples of the heterocyclic group represented by Y in the general formula (II) include indoline-2-ylidene and benz [e] indoline-2
-Ylidene, 2-benzothiazolinylidene, naphtho [2,1-d] thiazole-2 (3H) -ylidene, naphtho [1,2-d] thiazole-2 (1H) -ylidene, 1,4-dihydro Quinoline-4-ylidene, 1,2
-Dihydroquinoline-2-ylidene, 2-benzoselenazolinylidene and the like.

Examples of the alicyclic hydrocarbon ring formed by R ₃ and R ₄ together with adjacent carbon atoms include those having 3 to 8 carbon atoms. Well, for example, cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring,
Examples include a cyclooctane ring, a cyclopentene ring, a 1,3-cyclopentadiene ring, a cyclohexene ring, a cyclohexadiene ring, and the like.

Now, a general method for producing the compound (II) will be described. Reaction formula (1-a)

Embedded image

Reaction formula (1-b)

Embedded image

Reaction formula (1-c)

Embedded image

Reaction formula (1-d)

Embedded image

In the above reaction formula, R ₁ , R ₂ , Z, M ₁ and m 1 are as defined above, Q represents a hydrogen atom, potassium, sodium and the like, and Me represents methyl.

In the above reaction formula (1-a), compound (V) is prepared by combining compound (III) and 0.5 to 2 moles of compound (IV) in a solvent, if necessary, in the presence of a base at room temperature. ~ 40
It is obtained by reacting at 30 ° C for 30 minutes to 15 hours.
As the base, for example, an inorganic base such as potassium carbonate, sodium carbonate, or potassium hydroxide or an organic base such as triethylamine or sodium methoxide is used.
As the solvent, for example, methanol, ethanol, dimethylformamide and the like are used.

In the above reaction formula (1-b), compound (VI) can be obtained by treating compound (V) in an alkaline solvent or an acidic solvent at room temperature to 40 ° C. for 30 minutes to 15 hours. As the alkaline solvent, for example,
An aqueous solution of potassium carbonate, an aqueous solution of sodium carbonate, an aqueous solution of potassium hydroxide, or the like is used. As the acidic solvent, for example, an aqueous dimethyl sulfoxide solution of 50% volume / volume of hydrochloric acid, an aqueous dimethylformamide solution of 50% volume / volume of hydrochloric acid and the like are used.

In the above reaction formula (1-c), compound (VII) is compounded with compound (VI) in 0.5 to 2 moles of ZH
And, if necessary, in the presence of 0.5 to 2 moles of a base in a solvent at 80 to 120 ° C for 1 to 15 hours. As the solvent, for example, only an alcoholic solvent having 2 to 8 carbon atoms such as ethanol, propanol, isopropanol, butanol, octanol, or a mixed solvent of the alcoholic solvent and benzene, toluene or xylene (alcohol 50 vol / vol%) that's all)
Are used. As the base, for example, an organic base such as quinoline, triethylamine, pyridine or the like, or an inorganic base such as potassium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate or the like is used.

In the above reaction formula (1-d), the compound (II) is compounded with the compound (VII) by 0.5 to 2 moles of M ₁ ^{m1 +}
And, if necessary, in the presence of 0.5 to 2 moles of acetic acid in a solvent at room temperature to 120 ° C. for 1 to 15 hours. As a raw material that gives M ₁ ^{m1 +} , for example, aluminum trisacetylacetonate, aluminum trisethylacetoacetate, aluminum isoproxide, aluminum sec-butoxide, aluminum ethoxide, aluminum chloride, copper chloride, copper acetate, nickel acetate, etc. are used. Can be Examples of the solvent include halogen solvents such as chloroform and dichloromethane, aromatic solvents such as toluene and xylene, ether solvents such as tetrahydrofuran and methyl-tert-butyl ether, and ester solvents such as ethyl acetate.

The optical recording medium of the present invention is characterized in that the recording layer contains at least one azo metal chelate compound (I) and one squarylium metal chelate compound. By adding the azo metal chelate compound (I) to the squarylium metal chelate compound, photodeterioration of the squarylium metal chelate compound is further suppressed,
An optical recording medium having excellent light resistance can be obtained.

In the optical recording medium of the present invention, the weight ratio of the squarylium metal chelate compound to the azo metal chelate compound (I) is preferably from 90:10 to 20:80, and more preferably from 80:20 to 30:70. More preferably, there is. It is preferable in the above range from the viewpoint of light resistance, reflectance and modulation degree.

The physical properties required for the recording layer material include optical properties, thermal properties, and light resistance.

As the optical characteristics, the recording / reproducing wavelength of a DVD-R or the like is 600 to 720 nm, preferably 630 to 720 nm.
It is preferable to have a large absorption band on the short wavelength side with respect to 690 nm, and to have the recording / reproducing wavelength near the long wavelength end of the absorption band. This is the recording / reproducing wavelength of 600 to 72.
At 0 nm, it means that the recording layer material has a large refractive index and a predetermined extinction coefficient.

More specifically, it is preferable that the refractive index n of the single recording layer in the wavelength region of ± 5 nm near the long wavelength end of the absorption band is 1.5 or more and 3.0 or less. , The extinction coefficient k is preferably in the range of 0.02 or more and 0.3 or less. When n is 1.5 or more, a sufficient optical change can be obtained, so that the reflectance and the recording modulation degree become higher. Therefore, when n is 3.0 or less, the wavelength dependency is high. However, it is preferable that a reproduction error does not easily occur with light in the recording / reproduction wavelength region. k is 0.0
The case of 2 or more is preferable because the recording sensitivity is improved,
When k is 0.3 or less, a reflectance of 50% or more is more easily obtained, which is preferable. The maximum absorption wavelength (λmax) measured in a chloroform solution state is 550 to 600 nm.
Is preferable, and since the refractive index n can be increased as the extinction coefficient increases, the log ε (ε
Preferably have a molar extinction coefficient of 5 or more.

As a thermal characteristic, the decomposition temperature is preferably in a specific temperature range. Specifically, the decomposition temperature is 350
C. or lower is preferable, and those in the range of 250 to 350C are more preferable. When the decomposition start temperature is 350 ° C. or lower, it is not necessary to increase the power of the recording laser beam, and when it is 250 ° C. or higher, it is preferable in terms of recording stability.

Further, as light resistance, it is preferable to have reproduction stability of 1,000,000 times or more of repetition and fastness to prevent fading when left indoors.

The substrate usually has a depth of 1,000 to 2,500
案 内 guide groove. Track pitch is usually
Although it is 0.7 to 1.0 μm, it is 0.1 μm for high capacity applications.
7 to 0.8 μm is preferred. Groove width is 0.18 in half width
０．４0.40 μm is preferred. If it is 0.18 μm or more, it is easy to obtain a sufficient tracking error signal intensity.
When the thickness is 40 μm or less, it is preferable because the recording portion hardly spreads laterally when recording.

1. Structure of Optical Recording Medium The optical recording medium of the present invention may be a structure of FIG. 1 which is a normal write-once optical disk (a so-called air sandwich in which two sheets of FIG. 1 are bonded, or a close bonding structure). ) As well as the structure of the CD-R medium shown in FIG.
A media structure for DVD-R shown in FIG. 3 may be used.

2. Necessary Characteristics of Each Layer and Examples of Constituent Materials The optical recording medium of the present invention has a basic structure in which a first substrate and a second substrate are bonded together with an adhesive via a recording layer.
The recording layer may be a single layer of an organic dye layer, or may be a laminate of an organic dye layer and a metal reflective layer to increase the reflectance. The recording layer and the substrate may be layered with an undercoat layer or a protective layer interposed therebetween, or may be formed by laminating them for improving the function. The most commonly used structure is a first substrate / organic dye layer / metal reflective layer / protective layer / adhesive layer / second substrate structure.

<< Substrate >> The substrate to be used must be transparent to the laser used only when recording / reproducing is performed from the substrate side. When recording / reproducing is performed from the recording layer side, the substrate need not be transparent. As a 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. Note that a guide groove for racking, a guide pit, and a preformat such as an address signal may be formed.

<< Recording Layer >> The recording layer causes some optical change by irradiation with a laser beam and records information by the change. The recording layer contains the compound of the present invention. According to the present invention, the recording layer is used in combination of two or more kinds in forming the recording layer.

Tables 1 to 4 below show specific examples of the azo metal chelate compound (I) used in the present invention. In the table, Et represents ethyl, Bu represents n-butyl, and tBu represents tert-butyl.

[0102]

[Table 1]

[0103]

[Table 2]

[0104]

[Table 3]

[0105]

[Table 4]

Tables 5 to 7 below show specific examples of the squarylium metal chelate compound (II) used in the present invention. In the table,
Et represents ethyl, nPr represents n-propyl, iPr represents isopropyl, nBu represents n-butyl, and tBu represents tert-butyl. However, in the table, II-16 is a squarylium compound for a comparative example.

[0107]

[Table 5]

[0108]

[Table 6]

[0109]

[Table 7]

Further, the above compounds used in the present invention may be mixed or laminated with other organic dyes, metals and metal compounds for the purpose of improving optical characteristics, recording sensitivity, signal characteristics and the like.

Examples of other organic dyes include (poly) methine dye, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, and triene. Examples include phenylmethane-based, azulene-based, tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based dyes, and metal complex compounds. Examples of other metals and metal compounds include In, Te, Bi, S
e, Sb, Ge, Sn, Al, Be, TeO ₂ , Sn
O, As, Cd and the like can be mentioned. These can be used in the form of dispersion mixing or lamination.

Further, a polymer material, for example, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or a silane coupling agent is dispersed and mixed with the compound used in the present invention. Alternatively, a stabilizer (for example, a transition metal complex), a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like can be used together for the purpose of improving properties.

The recording layer is formed by vapor deposition, sputtering, C
It can be carried out by usual means such as VD or solvent application. In the case of using a coating method, the above compound used in the present invention is dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, and spin coating.

As the organic solvent used for forming the recording layer, generally, alcohols such as methanol, ethanol, isopropanol, 2,2,3,3-tetrafluoropropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, N Amides such as N, N-dimethylformamide, N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, ethers such as tetrahydrofuran, dioxane, diethyl ether, ethylene glycol monomethyl ether;
Methyl acetate, esters such as ethyl acetate, chloroform, methylene chloride, dichloroethane, carbon tetrachloride, aliphatic halogenated hydrocarbons such as trichloroethane, benzene, xylene, monochlorobenzene, aromatics such as dichlorobenzene, methoxyethanol, Examples include cellosolves such as ethoxyethanol, and hydrocarbons such as hexane, pentane, cyclohexane, and methylcyclohexane.

The thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.

<< Undercoat Layer >> The undercoat layer improves the adhesiveness,
It is used for the purpose of improving the storage stability of the recording layer, improving the reflectivity, protecting the substrate from a solvent, forming guide grooves, guide pits, preformats, and the like.

For the above purpose, polymer materials such as ionomer resins, polyamide resins, vinyl resins,
Various polymer compounds such as natural resins, natural polymers, silicones, liquid rubbers, and silane coupling agents can be used. For the above purpose, inorganic compounds other than the above-mentioned polymer materials, for example, SiO, MgF
₂ , SiO ₂ , TiO ₂ , ZnO, TiN, SiN, and the like, and furthermore, a metal or metalloid such as Z
n, Cu, Ni, Cr, Ge, Se, Au, Ag, Al
Etc. can be used. Metals, for example, Al, Au, Ag, etc., and organic thin films having metallic luster, for example, methine dyes, xanthene dyes, etc. can be used for the above purpose. Cured resin, thermosetting resin, thermoplastic resin, or the like can be used.

The thickness of the undercoat layer is 0.01 to 30 μm.
m, preferably 0.05 to 10 μm.

<< Metal Reflective Layer >> The metal reflective layer is made of a metal, a semi-metal, or the like which is highly resistant to corrosion and can provide a high reflectance by itself. Examples of the material include Au, Ag, Cr, Ni, Al, and F.
Although e, Sn and the like can be mentioned, Au, Ag, and Al are most preferable in terms of reflectance and productivity, and these metals and metalloids may be used alone or as two kinds of alloys.
Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 5000５０, preferably 100 to 300Å.
0 ° is appropriate.

<< Protective Layer, Hard Coat Layer on Substrate Surface >> The protective layer and the hard coat layer on the substrate surface protect the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., and preserve the recording layer (reflection / absorption layer). It is used for the purpose of improving the stability and the reflectance. For these purposes, the materials shown in the undercoat layer can be used. In addition, as the inorganic material, SiO, SiO ₂ or the like can be used,
As organic materials, polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, natural rubber, styrene butadiene resin, chloroprene rubber,
A heat-softening resin such as a wax, an alkyd resin, a drying oil, and rosin, a hot-melt resin, and an ultraviolet-curable resin can also be used. The most preferable example of the above materials is an ultraviolet curable resin having excellent productivity.

The thickness of the protective layer or the hard coat layer on the substrate surface is suitably 0.01 to 30 μm, preferably 0.05 to 10 μm.

In the present invention, a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, and the like are provided on the undercoat layer, the protective layer, and the hard coat layer on the substrate surface in the same manner as the recording layer. Agents, plasticizers, and the like.

<< Protective Substrate >> When the protective substrate is irradiated with laser light from the protective substrate side, it must be transparent to the laser light used.
Transparency does not matter. Available materials are exactly the same as the substrate material, polyester, acrylic resin, polyamide,
Plastic such as polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, and polyimide, glass, ceramic, and metal can be used.

<< Adhesive, Adhesive Layer >> Any material capable of adhering two recording media may be used, and from the viewpoint of productivity, an ultraviolet-curable or hot-melt adhesive is preferable.

[0125]

EXAMPLES Examples and comparative examples of the present invention will be described below.
Table 8 below shows the evaluation results of the optical recording media obtained in these Examples and Comparative Examples. The compounds used in Examples and Comparative Examples are those described in Tables 1 to 7.

(Example 1) Compound examples I-1 and II- were formed on a 0.6 mm-thick injection-molded polycarbonate substrate having a guide groove with a groove depth of 1740 °, a half width of 0.36 µm and a track pitch of 0.74 µm. The mixture of Example 1 (for the mixing ratio, see Table 8 below) was dissolved in 2,2,3,3-tetrafluoropropanol, and the solution was applied with a spinner to a thickness of 90.
An organic dye layer of 0 ° was formed, and then a reflective layer of 1300 ° of gold was provided by a sputtering method, and a 6 μm protective layer of acrylic photopolymer was provided thereon. Furthermore, the thickness is 0.
A 6 mm injection molded polycarbonate substrate was bonded with an acrylic photopolymer to obtain an optical recording medium.

(Examples 2 to 10) Optical recording media were formed in exactly the same manner as in Example 1 using the raw materials having the combinations shown in Table 8 below.

(Comparative Example 1) An optical recording medium was formed in the same manner as in Example 1 except that only II-15, which was a squarylium metal chelate compound, was used.

(Comparative Example 2) An optical recording medium was formed in exactly the same manner as in Example 1 except that only II-16, which was a squarylium metal chelate compound, was used.

[0130]

[Table 8]

<Recording Conditions> A semiconductor laser beam having an oscillation wavelength of 658 nm and a beam diameter of 0.9 μm was used as the optical recording medium, and an EFM signal (linear velocity of 3.5 m / m) was obtained by an optimized multi-pulse strategy while tracking. Sec) was recorded and reproduced with continuous light (reproduction power 0.7 mW) of a semiconductor laser having an oscillation wavelength of 658 nm, and the reproduction waveform and jitter were measured.

<Weather resistance test conditions> Light resistance test: 40,000 Lux, Xe light, continuous irradiation for 20 hours Storage test: 60 ° C., 90% RH, left for 600 hours

[0133]

[Table 9]

[0134]

1) Claims 1 to 6, 10 An optical information recording medium capable of recording and reproducing with a laser beam in the wavelength range of 600 to 720 nm, and having excellent light resistance and storage stability was provided. In particular, it has become possible to provide an optical recording medium having excellent light resistance as compared with a single squarylium metal chelate compound. 2) Claims 7 to 9 In addition to the first effect, an optical recording medium capable of recording and reproducing with a stable high reflectance and a high degree of modulation can be provided. 3) Claim 11 There is provided an optical recording method having the effects of the optical recording medium of claims 1 to 10. 4) Claim 12 An optical recording medium having the effects of the optical recording medium of claims 1 to 10 and the optical recording method of claim 11 is provided.

[Brief description of the drawings]

FIGS. 1A to 1D are schematic cross-sectional views of a general write-once optical recording medium to which the optical recording medium of the present invention is applied.

FIGS. 2A to 2C are schematic cross-sectional views of a CD-R medium configuration to which the optical recording medium of the present invention is applied.

FIGS. 3A to 3C are schematic cross-sectional views of a DVD-R medium configuration to which the optical recording medium of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Hard coat layer 6 Metal reflective layer 7 Protective substrate 8 Adhesive layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G11B 7/24 516 G11B 7/24 522A 522 538E 538 561N 561 B41M 5/26 Y (72) Inventor Tatsuya Tomura Ricoh, Inc. 1-3-6 Nakamagome, Ota-ku, Tokyo (72) Inventor Tsutomu Tsutomu 1-3-6, Nakamagome, Tokyo, Ota-ku, Ricoh Co., Ltd. (72) Yasunobu Ueno, Inventor Ota-ku, Tokyo 1-3-6 Nakamagome, Ricoh Co., Ltd. (72) Inventor Mune Noguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Ricoh Co., Ltd. (72) Inventor Ikuo Shimizu Daikyocho, Yokkaichi City, Mie Prefecture 3-chome Kyowa Yuka Co., Ltd. Yokkaichi Research Laboratory (72) Inventor Motoharu Kinugasa 2-3-3 Daikyocho, Yokkaichi-shi, Mie Kyowa Yuka Co., Ltd.Yokkaichi Research Laboratory (72) Inventor Hiroshi Toyoda 2-3-3 Daikyocho, Yokkaichi City, Mie Prefecture Kyowa Yuka Co., Ltd. 3rd Street Kyowa Yuka Co., Ltd. Yokkaichi Research Laboratories F-term (reference) 2H111 EA03 EA12 EA22 EA39 EA40 FA01 FA12 FA23 FA31 FB30 FB42 FB48 4H056 CA01 CC02 CC08 CE01 CE03 CE06 DD03 DD06 EA16 FA06 5D029 JA04 JC WB05A03 CC01 CC14 KK06

Claims (12)

[Claims] 1. An optical recording medium comprising at least a recording layer provided on a substrate, a squarylium metal chelate compound comprising a squarylium compound and a metal, an azo compound represented by the following general formula (I) and a metal: And an azo metal chelate compound comprising at least one of the following. Embedded image (In the formula, A represents a residue which forms a heterocyclic ring which may have a substituent together with a carbon atom and a nitrogen atom to which it is bonded, and B represents a group to which it is bonded. Represents a residue forming an aromatic ring which may have a substituent or a heterocyclic ring which may have a substituent together with two carbon atoms, and X represents a substituent having an active hydrogen group .) 2. A squarylium metal chelate compound and an azo metal chelate compound in a weight ratio of 90:10 to 20: 8.
2. The optical recording medium according to claim 1, wherein 0 is set. 3. The method according to claim 1, wherein the metal atom of the azo metal chelate compound is
3. The optical recording medium according to claim 1, wherein the optical recording medium is at least one selected from the group consisting of manganese, cobalt, nickel, and copper. 4. The optical recording medium according to claim 1, wherein the squarylium metal chelate compound is a compound represented by the following general formula (II). Embedded image [Wherein, R ₁ and R ₂ are the same or different substituents, and are a hydrogen atom, an alkyl group which may have a substituent,
Represents an aralkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent. M ₁ represents a metal atom having coordination ability. Z is an aryl group which may have a substituent, a heterocyclic group which may have a substituent, or Y = CH- (Y
Represents a heterocyclic group which may have a substituent).
m1 represents an integer of 2 or 3. ] 5. Z in the general formula (II) is represented by the following general formula (II-
The optical recording medium according to claim 4, wherein the optical recording medium is (II). Embedded image [Wherein, R ₃ and R ₄ are the same or different and each represents an alkyl group which may have a substituent, or R ₃ and R ₄ together with an adjacent carbon atom form an alicyclic group; R ₅ may form a hydrocarbon ring or a heterocyclic ring,
Represents 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, and R ₆ represents a halogen atom or a substituent. An alkyl group which may be substituted, an aralkyl group which may have a substituent, an aryl group which may have a substituent,
Represents a nitro group, a cyano group or an optionally substituted alkoxy group, and n represents an integer of 0 to 4, wherein
When n is 2 to 4, R ₆ may be the same or different;
Further, two adjacent R ₆ may be combined with two adjacent carbon atoms to form an aromatic ring which may have a substituent. ] 6. The optical recording medium according to claim 4, wherein M ₁ is aluminum. 7. A recording layer having a refractive index n of 1.5 ≦ n ≦ 3.0 and a extinction coefficient k of 0.02 ≦ k ≦ 0 with respect to light in a wavelength range of ± 5 nm. The optical recording medium according to any one of claims 1 to 6, wherein 8. A reflective layer having a reflective layer, the reflective layer comprising gold, silver, copper,
8. The optical recording medium according to claim 1, comprising aluminum or an alloy of these metals. 9. The track pitch on the substrate is 0.7-0.
8 μm, and the groove width is 0.18 to 0.4 at half width.
The optical recording medium according to any one of claims 1 to 8, wherein the optical recording medium is in a range of 0 µm. 10. The optical recording medium according to claim 1, wherein recording is possible at a wavelength of 600 to 720 nm. 11. An optical recording method comprising recording on the optical recording medium according to claim 1 at a wavelength of 600 to 720 nm. 12. An optical recording apparatus comprising the optical recording medium according to claim 1.