JP2002114922A - Azo metal chelate coloring matter and optical recording medium made by using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium having a high recording sensitivity and suitable for high speed recording. SOLUTION: An azo metal chelate coloring matter is made from an azo compound represented by general formula (I) (wherein A is a nitrogenous heterocyclic aromatic ring which may be substituted or may be combined with other aromatic or aliphatic ring to form condensed rings; Z is a group having an active hydrogen atom; and R1 and R2 are each independently H or an alkyl group, provided that at least one of them is an alkyl group) and a metal. The optical recording medium has a recording layer containing the coloring matter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azo metal chelate dye of an azo compound and a metal and an optical recording medium having a recording layer containing the same.

[0002]

2. Description of the Related Art In recent years, optical recording using a laser has been actively developed in order to enable high-density information recording and storage and reproduction thereof. As a medium used for the recording, conventionally proposed optical recording media include a magneto-optical recording medium, a phase-change optical recording medium, an optical recording medium of chalcogen oxide, and an organic recording medium of an organic dye type.

Of these, organic dye-based optical recording media are considered to be significant in that they are inexpensive and the manufacturing process is simple. As an organic dye-based optical recording medium, a type in which a metal layer having high reflectivity is laminated on an organic dye layer is mass-produced as a recordable compact disc (CD-R).

[0004] Dyes used in the recording layer of the CD-R include:
Various dyes such as cyanine dyes, phthalocyanine dyes, and metal chelate dyes have been proposed and put into practical use.However, the present inventors have focused on metal chelate dyes that are excellent in light resistance and environmental resistance. Starting from the inventions described in JP-A-3-818057 and JP-A-6-65514, many optical recording media using this type of dye have been proposed.

[0005]

Recently, with the speeding up of computers, there is a demand in the market for a CD-R capable of writing at a speed eight times or more that of a conventional computer. The present inventors have already disclosed Japanese Patent Application Laid-Open No. 2000-52656 and Japanese Patent Application No. 11-125.
No. 645 and Japanese Patent Application No. 11-210397 have been proposed, but the azo metal chelate dye has been newly improved so that high-speed recording can be performed and the recording sensitivity is improved. It was found that an optical recording medium was obtained.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to meet the above-mentioned demands in the market, and as a result, the compound can be synthesized by using a compound represented by the following general formula (II) as a coupling component. By using an azo metal chelate dye formed from the compound represented by the general formula (I) and a metal for the recording layer, it has been found that a good optical recording medium having excellent recording sensitivity can be obtained, and the invention has been completed. General formula (II)

[0007]

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(Wherein Z represents a group having active hydrogen;
¹ and R ² each independently represent a hydrogen atom or an alkyl group. However, at least one of R ¹ and R ² is an alkyl group. General formula (I)

[0009]

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(Wherein ring A represents a nitrogen-containing heteroaromatic ring which may have a substituent and may be condensed with another aromatic or aliphatic ring, and Z is an active Represents a group having hydrogen, and R ¹ and R ² are the same as defined in the general formula (II).) That is, the present invention provides an azo metal chelate dye of an azo compound represented by the following general formula (I) and a metal; An optical recording medium provided with a recording layer capable of recording or reproducing information by a laser on a substrate, wherein the recording layer contains the azo metal chelate dye. General formula (1)

[0011]

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(Each symbol in the formula is as described above.)

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. An optical recording medium using an azo metal chelate dye formed from an azo compound and a metal of the present invention in a recording layer has the characteristics that light resistance, environmental resistance are good, and recording sensitivity is high. In the general formula (1), ring A represents an aromatic heterocyclic ring having at least one nitrogen atom which may have a substituent, and may be condensed with another aromatic or aliphatic ring. No problem. General formula (I) constituting the azo metal chelate dye of the present invention
Group in the azo compound represented by

[0014]

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[0015] For example, a 5-membered ring containing nitrogen or 6-membered ring
Examples include a membered aromatic heterocyclic group or a condensed ring group obtained by condensing one or two 5-membered and / or 6-membered rings with these. Specifically, the following are mentioned, for example.

[0016]

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(Wherein, D ^{1 to} D ⁴ are each independently a hydrogen atom; methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-
C1-C6 linear or branched alkyl group such as butyl group, n-pentyl group, n-hexyl group; trifluoromethyl group, pentafluoroethyl group, 2-fluoroethyl group, 2,2-difluoroethyl Group, 2,2,2-trifluoroethyl group, 2H-tetrafluoroethyl group, heptafluoro-n-propyl group, 3,3,3-trifluoropropyl group, 1H, 1H-pentafluoropropyl group, 1H, 1H, 3H-tetrafluoropropyl group, perfluoro-n-butyl group, 1H, 1H-heptafluorobutyl group, 1H, 1H, 3H-hexafluorobutyl group, perfluoro-n-pentyl group, 1H, 1H, 5H
A straight-chain fluorinated alkyl group having 1 to 6 carbon atoms such as -octafluoropentyl group, perfluoro-n-hexyl group, 2- (perfluorobutyl) ethyl group; 1- (trifluoromethyl) tetrafluoroethyl group , 1- (trifluoromethyl) -2,2,2-trifluoroethyl group, 1-
(Trifluoromethyl) ethyl group, 1- (difluoromethyl) -2,2-difluoroethyl group, 1- (fluoromethyl) -2-fluoroethyl group, perfluoro-1,
1-dimethylethyl group, 1,1-di (trifluoromethyl) ethyl group, 1- (trifluoroethyl) -1-methylethyl group, 1-methyl-1H-perfluoropropyl group, 1-methyl-1H- Perfluorobutyl group, 2,2
-Di (trifluoromethyl) propyl group, 2-methyl-
4,4,4-trifluorobutyl group, perfluoro-3
A branched alkyl fluoride group having 1 to 6 carbon atoms such as -methylbutyl group, 2- (perfluoro-1-methylethyl) ethyl group and 3- (perfluoro-1-methylethyl) propyl group; trifluoromethoxy group Pentafluoromethoxy group, 2-fluoroethoxy group, 2,2-difluoroethoxy group, 2,2,2-trifluoroethoxy group, 2H
-Tetrafluoroethoxy group, heptafluoro-n-propoxy group, 3,3,3-trifluoropropoxy group,
1H, 1H-pentafluoropropoxy group, 1H, 1
H, 3H-tetrafluoropropoxy group, perfluoro-n-butoxy group, 1H, 1H-heptafluorobutoxy group, 1H, 1H, 3H-hexafluorobutoxy group,
Perfluoro-n-pentyloxy group, 1H, 1H, 5
H-octafluoropentyloxy group, perfluoro-
C1-C6 linear fluorinated alkoxy group such as n-hexyloxy group, 2- (perfluorobutyl) ethoxy group; 1- (trifluoromethyl) tetrafluoroethoxy group, 1- (trifluoromethyl) -2,2,2-trifluoroethoxy group, 1- (trifluoromethyl) ethoxy group, 1- (difluoromethyl) -2,2-difluoroethoxy group, 1- (fluoromethyl) -2-fluoroethoxy group, Perfluoro-1,1-dimethylethoxy group, 1,1-di (trifluoromethyl) ethoxy group, 1
-(Trifluoroethyl) -1-methylethoxy group, 1
-Methyl-1H-perfluoropropoxy group, 1-methyl-1H-perfluorobutoxy group, 2,2-di (trifluoromethyl) propoxy group, 2-methyl-4,4,
1 to 6 carbon atoms such as a 4-trifluorobutoxy group, a perfluoro-3-methylbutoxy group, a 2- (perfluoro-1-methylethyl) ethoxy group, and a 3- (perfluoro-1-methylethyl) propoxy group. A cyclic fluorinated alkoxy group; a cyclic alkyl group having 3 to 6 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group; a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, and n- Butoxy group, tert-
C1-C6 alkoxy groups such as butoxy group, sec-butoxy group, n-pentyloxy group, n-hexyloxy group; acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, pivaloyl group , A hexanoyl group, a heptanoyl group or the like having 2 to 7 carbon atoms
An alkylcarbonyl group having 2 to 2 carbon atoms such as a vinyl group, a propenyl group, a butynyl group, a pentenyl group and a hexenyl group;
A linear or branched alkenyl group having 6; a cyclic alkenyl group having 3 to 6 carbon atoms such as a cyclopentenyl group and a cyclohexenyl group; a halogen group such as a fluorine atom, a chlorine atom and a bromine atom; a formyl group; a hydroxyl group; Group;
1 carbon atom such as hydroxymethyl group, hydroxyethyl group, etc.
To 6 hydroxyalkyl groups; methoxycarbonyl groups,
An ethoxycarbonyl group, an n-propoxycarbonyl group,
Isopropoxycarbonyl group, n-butoxycarbonyl group, tert-butoxycarbonyl group, sec-butoxycarbonyl group, n-pentyloxycarbonyl group, n
An alkoxycarbonyl group having 2 to 7 carbon atoms such as -hexyloxycarbonyl group; a nitro group; a cyano group; an amino group;
C1-C10 such as methylamino group, ethylamino group, n-propylamino group, n-butylamino group, dimethylamino group, diethylamino group, di-n-propylamino group and di-n-butylamino group Alkylamino group; methoxycarbonylmethyl group, methoxycarbonylethyl group, ethoxycarbonylmethyl group, ethoxycarbonylethyl group, n-propoxycarbonylethyl group, n-propoxycarbonylpropyl group, isopropoxycarbonylmethyl group, isopropoxycarbonylethyl group, etc. A methylthio group, an ethylthio group, an n-propylthio group, an isopropylthio group, an n-butylthio group, a tert-butylthio group, a sec-butylthio group, an n-pentylthio group, n
An alkylthio group having 1 to 6 carbon atoms such as a hexylthio group;
Trifluoromethylthio, pentafluoroethylthio, 2-fluoroethylthio, 2,2-difluoroethylthio, 2,2,2-trifluoroethylthio,
2H-tetrafluoroethylthio group, heptafluoro-
n-propylthio group, 3,3,3-trifluoropropylthio group, 1H, 1H-pentafluoropropylthio group, 1H, 1H, 3H-tetrafluoropropylthio group, perfluoro-n-butylthio group, 1H, 1H -Heptafluorobutylthio group, 1H, 1H, 3H-hexafluorobutylthio group, perfluoro-n-pentylthio group, 1H, 1H, 5H-octafluoropentylthio group, perfluoro-n-hexylthio group, 2- ( C1-C6 linear fluorinated alkylthio group such as perfluorobutyl) ethylthio group; 1- (trifluoromethyl) tetrafluoroethylthio group, 1- (trifluoromethyl) -2,2,2-tri Fluoroethylthio group, 1-
(Trifluoromethyl) ethylthio group, 1- (difluoromethyl) -2,2-difluoroethylthio group, 1-
(Fluoromethyl) -2-fluoroethylthio group, perfluoro-1,1-dimethylethylthio group, 1,1-di (trifluoromethyl) ethylthio group, 1- (trifluoroethyl) -1-methylethylthio Group, 1-methyl-
1H-perfluoropropylthio group, 1-methyl-1H
-Perfluorobutylthio group, 2,2-di (trifluoromethyl) propylthio group, 2-methyl-4,4,4-
1 to 6 carbon atoms such as a trifluorobutylthio group, a perfluoro-3-methylbutylthio group, a 2- (perfluoro-1-methylethyl) ethylthio group, and a 3- (perfluoro-1-methylethyl) propylthio group. Branched alkylfluorthio groups; methylsulfonyl, ethylsulfonyl, n-propylsulfonyl, isopropylsulfonyl, n-butylsulfonyl, tert-butylsulfonyl, sec-butylsulfonyl, n-pentylsulfonyl, an alkylsulfonyl group having 1 to 6 carbon atoms such as an n-hexylsulfonyl group; a trifluoromethylsulfonyl group, a pentafluoroethylsulfonyl group, a 2-
Fluoroethylsulfonyl group, 2,2-difluoroethylsulfonyl group, 2,2,2-trifluoroethylsulfonyl group, 2H-tetrafluoroethylsulfonyl group,
Heptafluoro-n-propylsulfonyl group, 3,3
3-trifluoropropylsulfonyl group, 1H, 1H-
Pentafluoropropylsulfonyl group, 1H, 1H, 3
H-tetrafluoropropylsulfonyl group, perfluoro-n-butylsulfonyl group, 1H, 1H-heptafluorobutylsulfonyl group, 1H, 1H, 3H-hexafluorobutylsulfonyl group, perfluoro-n-pentylsulfonyl group, 1H, A linear alkylsulfonyl fluoride group having 1 to 6 carbon atoms such as a 1H, 5H-octafluoropentylsulfonyl group, a perfluoro-n-hexylsulfonyl group, a 2- (perfluorobutyl) ethylsulfonyl group; Fluoromethyl) tetrafluoroethylsulfonyl group, 1- (trifluoromethyl) -2,
2,2-trifluoroethylsulfonyl group, 1- (trifluoromethyl) ethylsulfonyl group, 1- (difluoromethyl) -2,2-difluoroethylsulfonyl group,
1- (fluoromethyl) -2-fluoroethylsulfonyl group, perfluoro-1,1-dimethylethylsulfonyl group, 1,1-di (trifluoromethyl) ethylsulfonyl group, 1- (trifluoroethyl) -1- Methylethylsulfonyl group, 1-methyl-1H-perfluoropropylsulfonyl group, 1-methyl-1H-perfluorobutylsulfonyl group, 2,2-di (trifluoromethyl)
Propylsulfonyl group, 2-methyl-4,4,4-trifluorobutylsulfonyl group, perfluoro-3-methylbutylsulfonyl group, 2- (perfluoro-1-methylethyl) ethylsulfonyl group, 3- (perfluoro −
1 carbon atom such as 1-methylethyl) propylsulfonyl group
To 6 branched alkylfluorsulfonyl groups; an aryl group having 6 to 16 carbon atoms which may have a substituent; an arylcarbonyl group having 7 to 17 carbon atoms which may have a substituent; ⁵ ＣC (CN) D ⁶ (D ⁵ is a hydrogen atom or a carbon atom having the same meaning as defined above in D ^{1 to} D ⁴
And D ⁶ represents a cyano group or an alkoxycarbonyl group having 2 to 7 carbon atoms as defined in the above D ^{1 to} D ⁴ . ). Further, among D ^{1 to} D ⁴ , adjacent groups may be bonded to each other to form a ring fused to ring A. )

Of the ten types of rings exemplified above, more preferred are a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a pyridine ring, a benzothiazole ring and a benzimidazole ring, and the most preferred is a thiazole ring. , An imidazole ring, a pyrazole ring, an isoxazole ring, a benzthiazole ring and a benzimidazole ring.

In the general formula (1) of the present invention, R ¹ and R ²
Each independently represents a hydrogen atom or an alkyl group, but the alkyl group may be branched, and has 1 to 10, preferably 1 to 3, and more preferably a methyl group or an ethyl group. When R ¹ and R ² are alkyl groups, the dye formed is less likely to be oxidized than when it is a hydrogen atom, resulting in excellent light resistance and storage stability. Further, Z in the general formula (1) of the present invention is not particularly limited as long as it is a group having active hydrogen.
For example _{-OH, -SH, -COOH, -SO 3} H, -B
(OH) ₂ , —NH ₂ , —NHR, —NHCOH, —NH
COR (wherein, R represents a optionally substituted alkyl group or a phenyl group.), - NHSO ₂ R (wherein R,
Is the same as defined above). In the present invention, specific examples of the azo compound that forms a complex with a metal include, for example, preferably the following.

[0020]

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[0021]

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In the present invention, the azo compound which forms a complex with a metal may be a single compound or a mixture of two or more types. When a complex is formed, there is an advantage that the solubility of the obtained metal chelate compound in a coating solvent is improved. Specific examples of the mixture of azo compounds that form a complex with a metal in the present invention include the following.

[0023]

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[0024]

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For example, in the case of a mixture of two azo compounds as in the above combination examples (a) and (b),
The ratio is 1 to 99:99 to 1 with the total number of seeds being 100.
And in the case of a mixture of four types as in (c),
Assuming that the total number of species is 100, the ratio is 1 to 97, respectively. What is necessary is just to adjust suitably so that the sensitivity and solubility of a mixture may become a preferable value.

Examples of combinations (b) and (c)
As described above, the combination of the azo compounds present in the same alkyl group at different substitution positions is the most preferable as the combination of the azo compounds used in the present invention, because the preparation method is simple and the recording characteristics are good. . In the present invention, the metal that forms a chelate with an azo compound is not particularly limited as long as it is generally a metal capable of forming a complex with such an azo compound.
Transition elements such as o, Fe, Ru, Rh, Pd, Os, Ir, and Pt are preferable, and Ni and Co are particularly preferable. Next, a method for producing a metal chelate dye compound of an azo compound and a metal used in the optical recording medium of the present invention will be described. The metal chelate compound of the azo compound and the metal used in the present invention can be synthesized, for example, by the following method. General formula (III)

[0027]

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(Wherein ring A has the same meaning as in formula (I)), and the diazo component represented by formula (II) is diazotized by a known method.

[0029]

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(Each symbol in the formula is as described above) to give a compound of the general formula (I)

[0031]

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An azo compound represented by the formula (wherein each symbol is as described above) can be synthesized. The compound represented by the general formula (II) used as a coupling component can be synthesized, for example, by the following method. The quinaldine is reduced by a known method such as electrolytic reduction, formic acid reduction, hydrogenation using a catalyst such as Pd-carbon, Pt-carbon, etc., and the resulting 1,2,3,4-tetrahydroquinaldine is reduced to Organi
c Synthesis is performed by reacting 1-bromo-3-chloropropane with reference to the method described in Synthesis Col. Vol. By sulfonating this methyljulolidine with fuming sulfuric acid, a mixture of the following two compounds is obtained.

[0033]

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Here, when it is desired to finally obtain one kind of azo compound, the desired compound is separated by ordinary means,
The following steps are performed. In addition, if the mixture is used as it is without being separated, an azo compound corresponding to the above-mentioned two compounds is formed. Therefore, the complex prepared using the azo compound necessarily becomes a mixture. When used in the optical recording medium of the present invention, it is preferable to use a mixture. Therefore, it is preferable to use the mixture as it is without intentionally separating the two compounds (coupling components) at this stage.

Compounds in which R ¹ and R ² in the formula (II) are each independently a hydrogen atom or an alkyl group other than a methyl group (provided that at least one of R ¹ and R ² is an alkyl group) )), Quinoline substituted at the 2-position with a desired alkyl group may be used instead of quinaldine, or may be appropriately modified after formation of a julolidine ring. In order to form a mixture of the azo compounds obtained after the coupling reaction, a mixture containing a plurality of the compounds represented by the formula (III) may be used as the diazo component. The azo compound of the present invention is reacted with the azo compound obtained as described above and a metal salt in water and / or an organic solvent such as dioxane, tetrahydrofuran, acetone, N, N-dimethylformamide, methanol and ethanol. A metal chelate compound of an azo compound and a metal used for a recording medium can be produced. Examples of the anion of the metal salt used for producing the metal chelate compound include SCN ⁻ , SbF ₆ ⁻ , Cl ⁻ ,
_{^{Br -, F -, ClO 4}} -, BF 4 -, PF 6 -, CH 3 CO
_{^{O -, TiF 6 -, SiF}} 6 2-, ZrF 6 2-, PhSO 3 -,
B ^- (Ph) 1-valent or preferably a divalent anion, such as _4, particularly CH ₃ COO ^-, Cl ^- is preferred.

Next, the optical recording medium of the present invention will be described. The optical recording medium of the present invention is basically composed of a substrate and a recording layer containing the compound, and further includes an undercoat layer, a metal reflective layer, a protective layer, and the like on the substrate as necessary. It may be provided. An example of a preferable layer configuration is a medium having a high reflectance in which a metal reflective layer such as gold, silver, and aluminum and a protective layer are provided on the recording layer. Less than,
The optical recording medium of the present invention will be described with a medium having this structure as an example. The material of the substrate in the optical recording medium of the present invention may be basically any material as long as it is transparent at the wavelength of recording light and reproduction light.

Examples of such a material include resins such as acrylic resins, methacrylic resins, polycarbonate resins, polyolefin resins (particularly, amorphous polyolefins), polyester resins, polystyrene resins, epoxy resins, and the like. And a resin in which a resin layer made of a radiation-curable resin such as a photo-curable resin is provided on glass can be used. In terms of high productivity, cost, and moisture absorption resistance, injection molded polycarbonate is preferred. Amorphous polyolefin is preferred from the viewpoint of chemical resistance, moisture absorption resistance, and the like. Further, a glass substrate is preferable in terms of high-speed response and the like. A resin substrate or a resin layer may be provided in contact with the recording layer, and a guide groove or pit for recording / reproducing light may be provided on the resin substrate or the resin layer. Such guide grooves and pits are preferably provided at the time of forming the substrate, but may be provided using an ultraviolet curable resin layer on the substrate. If the guide groove is spiral,
Preferably, the groove pitch is about 0.5 to 1.2 μm.

A recording layer containing the compound of the present invention is formed on a substrate or, if necessary, on an undercoat layer.
Examples of the method for forming the recording layer include thin film forming methods generally used such as a vacuum evaporation method, a sputtering method, a doctor blade method, a casting method, a spin coating method, and an immersion method. The coating method is particularly preferred. In the case of film formation by spin coating, the number of rotations is 500
After the spin coating, a treatment such as heating or exposure to a solvent vapor may be carried out.

The coating solvent for forming the recording layer by a coating method such as a doctor blade method, a casting method, a spin coating method, and a dipping method is not particularly limited as long as it is a solvent which does not attack the substrate. For example, ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellosolve solvents such as methyl cellosolve and ethyl cellosolve; chain hydrocarbon solvents such as n-hexane and n-octane Cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, tert-butylcyclohexane and cyclooctane; tetrafluoropropanol, octafluoropentanol,
Perfluoroalkyl alcohol solvents such as hexafluorobutanol; and hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate and methyl isobutyrate.

The recording layer is composed of a transition metal chelate compound (eg, acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α) as a singlet oxygen quencher in order to improve the stability and light resistance of the recording layer. -A recording sensitivity improver such as a diketone) or a metal compound for improving the recording sensitivity. Here, the metal compound refers to a compound in which a metal such as a transition metal is contained in the compound in the form of an atom, an ion, a cluster, or the like. Dihydroxyazobenzene-based complex,
Dioxime complex, nitrosoaminophenol complex,
Organometallic compounds such as pyridyltriazine-based complexes, acetylacetonate-based complexes, metallocene-based complexes, and porphyrin-based complexes are exemplified. The metal atom is not particularly limited, but is preferably a transition metal.

Further, if necessary, other types of dyes can be used in combination. Other dyes are not particularly limited as long as they have appropriate absorption mainly in a recording laser wavelength range. Also, 620 ~ like DVD-R
An optical recording medium that can be used for recording with laser light in a plurality of wavelength ranges can be used in combination with a dye suitable for recording with a red laser selected from 690 nm.

Other dyes include metal-containing azo dyes,
Phthalocyanine dye, naphthalocyanine dye, cyanine dye, azo dye, squarylium dye, metal-containing indoaniline dye, triarylmethane dye,
Examples include merocyanine dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, xanthene dyes, oxazine dyes, and pyrylium dyes.

Further, if necessary, a binder, a leveling agent, an antifoaming agent and the like can be used in combination. Preferred binders include polyvinyl alcohol, polyvinylpyrrolidone, nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polystyrene resin, urethane resin, polyvinyl butyral, polycarbonate, polyolefin and the like. The thickness of the recording layer is
Although the suitable film thickness differs depending on the recording method and the like, it is not particularly limited, but is usually 50 to 300 nm.

A reflective layer may be formed on the recording layer, and its thickness is preferably 50 to 300 nm. As a material of the reflection layer, one having sufficiently high reflectance at the wavelength of the reproduction light, for example, Au, Al, Ag, Cu, Ti, Cr,
It is possible to use metals of Ni, Pt, Ta, Cr and Pd singly or as alloys. Among them, Au,
Al and Ag have high reflectance and are suitable as a material for the reflective layer. In addition to these as main components, the following may be included. For example, Mg, Se, Hf, V, Nb, R
u, W, Mn, Re, Fe, Co, Rh, Ir, Cu,
Zn, Cd, Ga, In, Si, Ge, Te, Pb, P
Metals and metalloids such as o, Sn, and Bi can be mentioned. Among them, those containing Ag as a main component are particularly preferable because they are inexpensive, easily reflect a high reflectance, and when a print receiving layer described later is provided, a beautiful white ground color can be obtained. Here, the main component has a content of 50
% Or more.

It is also possible to form a multilayer film by alternately stacking low-refractive-index thin films and high-refractive-index thin films with a material other than a metal and use it as a reflective layer. Examples of the method for forming the reflective layer include a sputtering method, an ion plating method, a chemical vapor deposition method, and a vacuum vapor deposition method. In addition, a known inorganic or organic intermediate layer for improving reflectance, improving recording characteristics, improving adhesion, etc. on the substrate or under the reflective layer,
An adhesive layer can also be provided.

The material of the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. Examples of the organic material include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. In addition, as the inorganic substance, SiO ₂ , Si
N ₄ , MgF ₂ , SnO _{2 and the} like can be mentioned.

The thermoplastic resin, thermosetting resin and the like can be formed by dissolving in a suitable solvent, applying a coating solution, and drying. The UV-curable resin can be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure the resin. As UV curable resin,
For example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used. These materials may be used singly or as a mixture, or may be used not only as a single layer but also as a multilayer film.

As a method of forming the protective layer, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used as in the case of the recording layer. Among them, the spin coating method is preferable. The thickness of the protective layer is generally 0.1 to
It is in the range of 100 μm, but in the present invention, it is 3 to 30 μm.
m is preferred.

Further, a substrate may be further bonded to the reflective layer surface, or two optical recording media may be bonded to each other with the reflective layer surfaces facing each other. An ultraviolet curable resin layer, an inorganic thin film, or the like may be formed on the mirror surface of the substrate for surface protection and prevention of adhesion of dust and the like. In addition, on a surface other than the incident surface of the recording / reproducing light, a print receiving layer capable of writing (printing) on various printers such as ink jet and thermal transfer, or various writing instruments may be provided.

[0050]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention unless it exceeds the gist of the invention. Example 1 1) Production example of metal chelate compound 25 g of 2-methyl-1,2,3,4-tetrahydroquinoline was added to 1-bromo-3-chloropropane, and the mixture was refluxed for 12 hours while stirring. After cooling, the obtained crystals were filtered, dispersed in 400 ml of water, and adjusted to pH 9 by adding sodium carbonate. This mixture is mixed with toluene 1
After extracting with 20 g and discarding the aqueous layer, the toluene layer was extracted with 54 g of concentrated sulfuric acid to obtain a sulfuric acid solution of methyljulolidine. 59 g of 60% fuming sulfuric acid
Into the solution at a temperature not exceeding 40 ° C, and
After stirring at 5 ° C for 2 hours, release into 224g of ice water,
An aqueous solution of 2-methyljulolidinesulfonic acid (a mixture of two compounds represented by the following structural formula) was obtained.

[0051]

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To this solution are added 180 ml of methanol, 0.93 g of urea and 4.55 g of sodium acetate. Further, 10% aqueous ammonia was added until the pH reached 3.5 to obtain a coupling solution. Next, 5.09 g of 2-amino-6-bromobenzothiazole was added to 46 g of acetic acid.
While stirring this mixture, 45 g of 75% phosphoric acid and 7.44 g of sulfuric acid were added thereto, and 7.0 g of a 43% nitrosyl sulfuric acid aqueous solution of sulfuric acid was added at 5 ° C or lower, and the mixture was stirred at 5 ° C or lower for 2 hours to obtain a diazo solution.

Next, the diazo solution was dropped into the coupling solution little by little. At this time, the pH is 3 to 3.
10% ammonia water is appropriately added so as to maintain the range of 5,
The temperature of the coupling solution was externally cooled so as not to exceed 5 ° C. After completion of the addition of the diazo solution,
After stirring for an hour, the mixture was further stirred for 1 hour at 15 to 25 ° C., and the obtained crystals were filtered. This crystal is 214m in water
, stirred at room temperature for 1 hour and filtered.
Brown crystals of an azo compound (mixture) represented by the following two types of structural formulas were obtained.

[0054]

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10 mmol of wet crystals of the obtained azo compound
The equivalent was added to 200 ml of methanol, and the mixture was stirred at room temperature for 1 hour, and then insolubles were removed by filtration. While stirring this at room temperature, a solution in which 1.37 g of nickel acetate tetrahydrate was dissolved in 14 ml of methanol was added dropwise. After stirring at room temperature for 1 hour, the formed crystals are filtered. The obtained crystals were washed with a small amount of methanol and dried to obtain 3.46 g of a target metal chelate compound of the present azo compound and a metal. This compound is considered to be a mixture of a plurality of chelating compounds, and its typical structural formula can be represented by the following formula (a). The maximum absorption wavelength of this compound in a chloroform solution is 690 nm and the molecular weight is 107
The molecular extinction coefficient assuming 1.6 was 1280. FIG. 1 shows the absorption spectrum in a chloroform solution. Structural formula (a)

[0056]

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2) Preparation of recording medium A 3% solution of octafluoropentanol of the nickel complex (a) of the azo compound obtained in the above 1) Preparation of metal chelate compound was prepared and filtered through a filter having a pore size of 0.22 μm. Thus, a dye solution was obtained. This dye solution was dropped onto an injection-molded polycarbonate resin substrate (120 mm in diameter) in which a guide groove was previously formed, applied by a spinner method, and dried at 80 ° C. for 5 minutes. The maximum absorption wavelength of the obtained coating film was 719 nm. FIG. 2 shows the absorption spectrum of the coating film. Next, an Ag film having a thickness of 1000 ° was formed on the coating film by a sputtering method to form a reflection layer.
Further, an ultraviolet-curable resin was spin-coated on the reflective film, and the resin was cured by irradiating it with ultraviolet light to form a protective layer having a thickness of 5 μm.

3) Evaluation Example While rotating the recording medium at 11.2 m / s, a laser beam having a center wavelength of 780 nm was irradiated at 17 mW which is the optimum recording power of the recording medium, and an EFM signal was recorded. Next, when the recorded portion was reproduced using a CD player having a center wavelength of 780 nm, a good reproduced signal was obtained. The light resistance (xenon fade meter accelerated test: 20 hours) and storage stability test (70 ° C., 85
(% RH: 100 hours) When the test was performed, no deterioration in sensitivity and recording characteristics was observed as compared with the initial stage, and the optical recording medium was extremely excellent.

COMPARATIVE EXAMPLE An optical recording medium was prepared under the same conditions as in the example by using the compound represented by the following structural formula (b), which was synthesized with substantially the same formulation as in the example. Structural formula (b)

[0060]

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While rotating the recording medium at 11.2 m / s, a laser beam having a center wavelength of 780 nm was irradiated at a recording power of 17 mW to record an EFM signal. Next, when this recording portion was reproduced using a CD player having a center wavelength of 780 nm, noise was large and reproduction was unstable. Further, while rotating this recording medium at 11.2 m / s,
A laser beam having a center wavelength of 780 nm was irradiated at 19 mW which is the optimum recording power of the recording medium, and an EFM signal was recorded. Next, when the recorded portion was reproduced using a CD player having a center wavelength of 780 nm, a good reproduced signal was obtained. As described above, since the example can perform good reproduction with a lower recording power than the comparative example, it can be seen that the optical recording medium of the present invention has good recording sensitivity and is suitable for high-speed recording.

[0062]

According to the present invention, it is possible to provide an optical recording medium having high recording sensitivity, which is very suitable for high-speed recording using a laser required in the market.

[Brief description of the drawings]

FIG. 1 is an absorption spectrum of an azo metal chelate dye of the present invention in a chloroform solution.

FIG. 2 is an absorption spectrum of a coating film containing the azo metal chelate dye of the present invention.

Claims (7)

[Claims] 1. An azo metal chelate dye of an azo compound represented by the following general formula (I) and a metal. General formula (I) (Wherein, ring A represents a nitrogen-containing heteroaromatic ring which may have a substituent and may be condensed with another aromatic or aliphatic ring, and Z has an active hydrogen R represents a group
¹ and R ² each independently represent a hydrogen atom or an alkyl group. However, at least one of R ¹ and R ² is an alkyl group. ) 2. An azo compound represented by the general formula (I):
Wherein R ¹ is an alkyl group and R ² is a hydrogen atom;
The azo metal chelate dye according to claim 1, wherein R ¹ is a hydrogen atom and R ² is an alkyl group. 3. The azo metal chelate dye according to claim ² , wherein R ¹ and R ² represent the same alkyl group. 4. In the formula, Z represents —SH, —SO ₂ H, —SO _{3
H, -NH 2, -NHR, -OH} , -COOH, -B
(OH) ₂ , —PO (OH) ₂ , —NHCOH, —NHC
4. The method according to claim _{1, wherein} OR or -NHSO2R (where R represents an aromatic ring or an alkyl group having 1 to 6 carbon atoms which may have a substituent). Azo metal chelate dyes. 5. The azo metal chelate dye according to claim 1, wherein the metal is a transition metal. 6. The metal is Ni, Co, Fe, Zn, Cu,
The azo metal chelate dye according to any one of claims 1 to 5, which is any one of Pd, Pt, Ru, Rh, and Os. 7. An optical recording medium provided with a recording layer on which information can be recorded or reproduced by a laser on a substrate, wherein the recording layer contains the azo metal chelate dye according to any one of claims 1 to 6. Optical recording medium.