JP2008106268A - Metal-chelate azo dye and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-chelate azo dye suitable for a recording layer for an optical recording medium and to provide an optical recording medium. <P>SOLUTION: The metal-chelate azo dye comprises an azo dye compound represented by formula (1) and a metal. In the formula, R<SB>1</SB>is a linear or branched alkyl group which may be substituted or a cycloalkyl group which may be substituted; R<SB>2</SB>and R<SB>3</SB>are each independently a hydrogen atom, a linear or branched alkyl group which may be substituted, an aryl group which may be substituted or a heterocyclic group which may be substituted; R<SB>4</SB>, R<SB>5</SB>, R<SB>6</SB>, R<SB>7</SB>and R<SB>8</SB>are each independently a hydrogen atom or a linear or branched alkyl group which may be substituted, provided that R<SB>4</SB>and R<SB>5</SB>, R<SB>4</SB>and R<SB>6</SB>, or R<SB>5</SB>and R<SB>7</SB>may be bonded together to form a ring; and Y is a linear or branched alkyl group substituted with at least two fluorine atoms. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an azo metal chelate dye having a high reflectance and an optical recording medium using the same for a recording layer, and more specifically, an optical recording medium capable of high-speed recording, and a recording layer of an optical recording medium having a plurality of recording layers. And an optical recording medium (hereinafter, sometimes referred to as “disk” or “optical disk”).

  In recent years, the size of data that can be handled has increased with the increase in the speed of computers and the increase in hard disk capacity. In order to cope with this, DVD-R has been developed as a large capacity recording medium. Various dyes such as cyanine and metal chelate dyes have been proposed for use in the recording layer of DVD-R. Among these dyes, many optical recording media using metal chelate dyes having excellent recording properties such as light resistance and durability have been proposed (see Patent Documents 1 to 3).

  Moreover, as a pigment | dye used for an optical recording medium, the compound which has a pyrimidine ring as a diazo component as described in patent document 4-patent document 6 is proposed. However, the compounds described in Patent Document 4 and Patent Document 5 can be recorded with a laser having a wavelength of 635 nm called authoring, but are difficult to record with a laser having a wavelength of 650 nm generally used for DVD-R. It turned out to be. Also, Patent Document 6 reports an example in which a compound having a pyrimidine ring as a diazo component is used for an optical recording medium and is recorded at 1 × speed, but the recording sensitivity is poor.

Japanese Patent Laid-Open No. 03-268994 JP 11-166125 A JP 2000-309722 A JP-A-10-157300 Japanese Patent Laid-Open No. 10-181203 JP 2002-029441 A

Recently, with the further increase in the amount of data, increasing the recording speed for recording information on an optical recording medium is emphasized. For example, in DVD-R, the normal recording speed is about 3.5 m / s (hereinafter sometimes referred to as 1X), but it is about 28 m / s (hereinafter sometimes referred to as 8X), which is eight times this. There is a demand for optical recording media capable of recording information at a high speed.
However, when recording is performed at such a high speed, the amount of light used for recording (laser power in the case of a laser) is relatively reduced. Accordingly, there is a demand for a dye that can be recorded even with a weak laser power.

On the other hand, multilayer recording media having two or more recording layers have been proposed as means for increasing the capacity of optical recording media. In the case of an optical recording medium having multiple recording layers on one side, the light used for recording / reproduction is incident from one side, but the laser power applied to the recording layer far from the incident surface is low. It will be a thing. Therefore, there is a need for a high-sensitivity dye capable of recording with a weak laser power, even in a multilayer recording medium, and a high-reflectance dye with low absorption so that recording light can efficiently reach a recording layer far from the incident surface. ing.
However, the present condition is that the pigment | dye which fully satisfies the above requirements has not yet been clarified.

In view of the above problems, an object of the present invention is to provide an azo metal chelate dye that can be applied to an optical recording medium capable of recording at a high speed of 8 times or more, and a recording layer of a multilayer recording medium having two or more recording layers. There is to do.
Another object of the present invention is to provide an optical recording medium using the above-mentioned azo metal chelate dye.

  The present inventors aimed to obtain an azo metal chelate dye having high sensitivity and high reflectance characteristics. Specifically, the inventors have found that the above problem can be solved by introducing a specific structure into an azo and metal chelate dye having a pyrimidine ring as a diazo component, and the present invention has been completed.

  Thus, according to the present invention, there is provided an azo metal chelate dye comprising an azo dye compound represented by the following general formula (1) and a metal.

(In the general formula (1), R ₁ is an optionally substituted linear or branched alkyl group or an optionally substituted cycloalkyl group. R ₂ and R ₃ are each independently R ₄ , R ₅ , R ₆ , R ₇ are a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. And R ₈ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R ₄ and R ₅ , R ₄ and R _6, R ₅ and R ₇ are bonded to each other And Y may be a linear or branched alkyl group substituted with at least two fluorine atoms, a metal from which a proton is eliminated from the compound of the above general formula (1), and a metal. To form a chelate dye.)

  Moreover, it is preferable that the said metal is either Ni, Co, Cu, or Pd.

  The present invention also provides an azo metal chelate dye comprising an azo dye compound represented by the following general formula (2) and Ni.

(In General Formula (2), R ₁₁ is an optionally substituted linear or branched alkyl group or an optionally substituted cycloalkyl group. R ₁₂ and R ₁₃ are each independently, hydrogen atom, a linear optionally substituted or branched alkyl group, optionally substituted aryl group, or is an optionally substituted heterocyclic group .R ₁₄ is good linear substituted R _{15 to} R ₂₀ each independently represents a hydrogen atom or an optionally substituted straight chain or branched alkyl group, from the compound of the above general formula (2) to a proton. The chelate dye is composed of the metal from which the is desorbed and the metal.)

In the azo dye compound represented by the general formula (2), R ₁₁ is a linear or branched alkyl group having 1 to 4 carbon atoms, R ₁₂ is an unsubstituted or halogen-substituted alkyl group or aryl group, R _It is preferable that ₁₃ is a hydrogen atom, R ₁₄ is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 8 carbon atoms, and R _{15 to} R ₂₀ are hydrogen atoms.

Next, according to the present invention, there is provided a recording layer containing an azo metal chelate dye composed of the azo dye compound represented by the general formula (1) or the general formula (2) and a metal. An optical recording medium is provided.
Here, the optical recording medium to which the present invention is applied has two or more recording layers, and at least one recording layer is composed of an azo dye compound represented by the general formula (1) or the general formula (2) and a metal. It is preferable to contain the azo metal chelate pigment | dye which becomes.
The optical recording medium is preferably capable of recording at 8 × speed or higher.

  ADVANTAGE OF THE INVENTION According to this invention, the azo metal chelate pigment | dye and optical recording medium suitable for the optical recording medium which can record at high speed, and the recording layer of the optical recording medium which has a recording layer in multiple layers are provided.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment of the present invention) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

Hereinafter, the azo metal chelate dye to which this embodiment is applied will be described.
The azo metal chelate dye to which this embodiment is applied is formed by chelate bonding between an azo dye compound represented by the following general formula (1) and a metal.
The azo dye compound represented by the general formula (1) is formed by combining a coupler component having a pyrimidine ring as a diazo component and having at least a fluorine-substituted alkylsulfonylamino group and an amino group. The optical recording medium containing the azo metal chelate dye having such a structure in the recording layer is excellent in weather resistance, and the reflectance is improved due to the high absorption coefficient of the dye. Furthermore, since the pyrimidine ring of the diazo component is substituted with an ester group, the light resistance is excellent. This is presumably because the electron withdrawing group was replaced with a pyrimidine ring, which decreased the electron density of the pyrimidine ring and stabilized the electron back-donation from the chelating metal.

(In the general formula (1), R ₁ is a linear or branched alkyl group which may be substituted or a cycloalkyl group which may be substituted, and R ₂ and R ₃ are each independently R ₄ , R ₅ , R ₆ , R ₇ represents a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. And R ₈ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R ₄ and R ₅ , R ₄ and R _6, R ₅ and R ₇ are bonded to each other Y may be a linear or branched alkyl group substituted with at least two fluorine atoms, and a metal from which a proton is eliminated from the compound of the general formula (1). To form a chelate dye.)

In General Formula (1), R ₁ is a linear or branched alkyl group which may be substituted, or a cycloalkyl group which may be substituted. R ₁ is, for example, an unsubstituted linear or branched alkyl group, or an unsubstituted cycloalkyl group, a linear or branched alkyl group substituted with fluorine, a linear chain substituted with an alkoxy group, or Branched alkyl groups are preferred.

R ₁ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms such as ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, sec-butyl, etc .; cyclopropyl A cycloalkyl group having 3 to 8 carbon atoms such as a group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.
Particularly preferably, from the reason that the steric hindrance is small, a linear alkyl group having 1 to 2 carbon atoms such as a methyl group or an ethyl group; a cycloalkyl group having 3 to 6 carbon atoms such as a cyclopentyl group or a cyclohexyl group. Is mentioned.
Examples of the substituent for the alkyl group or cycloalkyl group represented by R ₁ include a halogen atom, a substituent containing a typical element such as oxygen, nitrogen, and sulfur, and the like, but is preferably unsubstituted.

R ₂ and R ₃ each independently represent a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. . Here, examples of the linear or branched alkyl group which may be substituted include the same groups as those described above for R ₁ .
Examples of the aromatic ring as the aryl group include benzene and naphthalene. Examples of the heterocyclic ring as the heterocyclic group include unsaturated heterocycles such as pyridine, pyrimidine, thiophene, and furan; , Saturated heterocyclic rings such as pyridone, piperidine, morpholine, and tetrahydrofuran.

Examples of the substituent substituted on the aryl group or heterocyclic group include an alkyl group, an alkoxy group, an amino group, and a halogen atom.
Among them, as R ₂ and R ₃ , alkyl groups such as hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, and isobutyl group; halogen-substituted alkyl groups such as trifluoromethyl group and pentafluoroethyl group; An aromatic ring such as a phenyl group and a naphthyl group; a halogen-substituted aromatic ring such as a pentafluorophenyl group; and an unsaturated heterocyclic ring such as pyridine and pyrimidine are preferred.

As a specific compound of the diazo component in which the pyrimidine ring in the general formula (1) is substituted with CO ₂ R ₁ , those having the following structures are preferable examples.

In the coupler component in the general formula (1), the benzene ring is substituted with NHSO ₂ Y. Here, Y is a linear or branched alkyl group substituted with at least two fluorine atoms. As the alkyl group, a linear or branched alkyl group having 1 to 6 carbon atoms is more preferable. The alkyl group for Y is more preferably a linear alkyl group having 1 to 3 carbon atoms. The number of fluorine atoms to be substituted is usually 2 or more, and is usually 7 or less, preferably 5 or less, more preferably 3 or less. Specific examples of Y include difluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluoropropyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, and the like. Can be mentioned. Y is particularly preferably a trifluoromethyl group or a 2,2,2-trifluoroethyl group.

R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom or a linear or branched alkyl group which may be substituted. R ₄ , R ₅ , R ₆ , R ₇ and R ₈ include, for example, hydrogen atom; carbon such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, etc. A linear alkyl group having 1 to 6 carbon atoms; a branched alkyl group having 3 to 8 carbon atoms such as isopropyl group, sec-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclopropyl group, cyclohexylmethyl group, etc. Can be mentioned.

  These linear and branched alkyl groups may be further substituted. Examples of the substituent of the linear or branched alkyl group include a halogen atom, an alkoxy group, an alkoxycarbonyl group, an alkylcarbonyloxy group, an alkylcarbonyl group, a dialkylamino group, and the like, for example, fluorine, chlorine, bromine, iodine, etc. A halogen atom of: methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, cyclopropyloxy group, cyclohexylmethyl An alkoxy group having 1 to 8 carbon atoms such as an oxy group and a 2-ethylhexyloxy group; a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an isopropoxycarbonyl group, an n-butoxycarbonyl group, an isobutoxycarbonyl group, sec -Butoxycarbo An alkoxycarbonyl group having 2 to 9 carbon atoms, such as a methyl group, a t-butoxycarbonyl group, an n-pentyloxycarbonyl group, a cyclopropyloxycarbonyl group, a cyclohexylmethoxycarbonyl group, a 2-ethylhexyloxycarbonyl group; a methylcarbonyloxy group; Ethylcarbonyloxy group, n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, isobutylcarbonyloxy group, sec-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, An alkylcarbonyloxy group having 2 to 9 carbon atoms such as cyclopropylcarbonyloxy group, cyclohexylmethylcarbonyloxy group, 2-ethylhexylcarbonyloxy group; acetyl group, propio Alkyl having 2 to 9 carbon atoms, such as a ruthel group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylbutyryl group, pivaloyl group, hexanoyl group, cyclopropylcarbonyl group, cyclohexylmethylcarbonyl group, 2-ethylhexylcarbonyl group Carbonyl group; dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di-t-butylamino group, dihexylamino group, ethylmethylamino group, butylpentylamino group, etc. A dialkylamino group having 2 to 16 carbon atoms; and the like.

R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are preferably a hydrogen atom or a linear alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. It is. The alkyl group is preferably unsubstituted.

R ₄ and R ₅ , R ₄ and R _{6, and} R ₅ and R ₇ may be bonded to each other to form a ring. The ring to be formed is not limited, and examples thereof include a saturated or unsaturated 3-membered to 8-membered carbocycle or heterocycle. As a preferable ring, R ₄ and R ₆ or R ₄ and R ₅ are bonded to each other to form a 5-membered ring to a 7-membered ring, and all the atoms other than the nitrogen atom shown in the general formula (1) are formed of carbon. A saturated ring. The ring to be formed may have a substituent. Most preferably, R ₄ and R ₆ are bonded to each other to form a 5-membered ring to a 7-membered ring, and a saturated ring in which all of the nitrogen atoms other than the nitrogen atom shown in the general formula (1) are all formed of carbon. This is the case when it is substituted or substituted with 1 to 3 methyl groups.

  Among the azo dye compounds represented by the general formula (1), preferred compounds include compounds represented by the following general formula (2).

(In the general formula (2), R ₁₁ is a linear or branched alkyl group which may be substituted or a cycloalkyl group which may be substituted, and R ₁₂ and R ₁₃ are each independently R ₁₄ represents a hydrogen atom, a linear or branched alkyl group which may be substituted, an aryl group which may be substituted, or a heterocyclic group which may be substituted; A chain or branched alkyl group, and R _{15 to} R ₂₀ each independently represents a hydrogen atom or an optionally substituted linear or branched alkyl group, from the compound of the above general formula (2) to a proton; The chelate dye is composed of the metal and the metal from which

In the general formula (2), R ₁₁ is a linear or branched alkyl group which may be substituted or a cycloalkyl group which may be substituted. Specifically, R ₁₁ in the general formula (1) and It is the same.

R ₁₂ and R ₁₃ are each independently a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocycle; Specifically, it is the same as R ₂ and R ₃ in the general formula (1). Among them, it is particularly preferable that R ₁₂ is an unsubstituted or halogen-substituted alkyl group or aryl group, and R ₁₃ is a hydrogen atom.

R ₁₄ is a linear or branched alkyl group which may be substituted. As R ₁₄ , for example, a straight-chain alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group; isopropyl group, sec-butyl group, isobutyl group, t- Examples thereof include branched alkyl groups having 3 to 8 carbon atoms such as a butyl group, 2-ethylhexyl group, cyclopropyl group, and cyclohexylmethyl group. These alkyl groups may be substituted. Examples of the substituent include a halogen atom, an alkoxy group, an alkoxycarbonyl group, an alkylcarbonyloxy group, an alkylcarbonyl group, a dialkylamino group, and the like, for example, a halogen atom such as fluorine, chlorine, bromine, iodine; methoxy group, ethoxy Group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, cyclopropyloxy group, cyclohexylmethyloxy group, 2-ethylhexyloxy group An alkoxy group having 1 to 8 carbon atoms such as methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, t -Butoki C2-C9 alkoxycarbonyl groups such as carbonyl group, n-pentyloxycarbonyl group, cyclopropyloxycarbonyl group, cyclohexylmethoxycarbonyl group, 2-ethylhexyloxycarbonyl group; methylcarbonyloxy group, ethylcarbonyloxy group N-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, isobutylcarbonyloxy group, sec-butylcarbonyloxy group, t-butylcarbonyloxy group, n-pentylcarbonyloxy group, cyclopropylcarbonyloxy Group, cyclohexylmethylcarbonyloxy group, 2-ethylhexylcarbonyloxy group, etc., C2-C9 alkylcarbonyloxy group; acetyl group, propionyl group C2-C9 alkylcarbonyl such as butyryl, isobutyryl, valeryl, isovaleryl, 2-methylbutyryl, pivaloyl, hexanoyl, cyclopropylcarbonyl, cyclohexylmethylcarbonyl, 2-ethylhexylcarbonyl, etc. Group: carbon such as dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di-t-butylamino group, dihexylamino group, ethylmethylamino group, butylpentylamino group, etc. Examples thereof include dialkylamino groups having 2 to 16 carbon atoms.

Among these, R ₁₄ is preferably an unsubstituted linear alkyl group having 1 to 6 carbon atoms or an unsubstituted branched alkyl group having 3 to 8 carbon atoms. When an unsubstituted linear alkyl group is used, the carbon number is preferably 5 or less, more preferably 4 or less. The total carbon number of R ₁₄ is preferably 7 or less, more preferably 6 or less, still more preferably 5 or less, and particularly preferably 4 or less. R ₁₄ is particularly preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or an isobutyl group.

R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ , R ₁₉ and R ₂₀ each independently represent a hydrogen atom or an optionally substituted linear or branched alkyl group. As the linear or branched alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, and an alkyl group having 1 or 2 carbon atoms is particularly preferable. When R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ , R ₁₉ and R ₂₀ are alkyl groups having 1 to 2 carbon atoms, the hydrogen atom bonded to the carbon atom is replaced with other substituents (for example, halogen atoms). ), But is preferably an unsubstituted alkyl group, and examples thereof include a methyl group and an ethyl group. From the viewpoint of ease of synthesis and three-dimensional structure, hydrogen atoms are most preferable as R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ , R ₁₉ and R ₂₀ .

  The molecular weight of the azo dye compound represented by the general formula (1) is usually 2,000 or less. Among them, an azo dye compound having a molecular weight of 1,500 or less is preferable because solubility in a solvent is increased and a dye excellent in light resistance, weather resistance, and high reflectance can be obtained. Among the azo dye compounds represented by the general formula (1), specific examples of the compounds include the following.

  There are no particular restrictions on the azo metal chelate dye other than the chemical structure. However, from the viewpoint of use in an optical recording medium that can be recorded and reproduced with a short-wavelength laser beam that will be increasingly required in the future, a dye having an absorption maximum at a wavelength of 700 nm or less when measured for a dye monolayer film is more. A dye having an absorption maximum at a wavelength of 650 nm to 500 nm is more preferable.

  In the azo metal chelate dye of the present invention, the metal that forms a chelate with the azo dye compound represented by the general formula (1) is not limited, but is preferably any one of Ni, Co, Cu, and Pd. Is preferred. By using the above metal as the metal, the light resistance, weather resistance, and the like of the azo metal chelate dye are improved. Since these metals can form a complex of two tridentate ligands and a hexacoordinate octahedral structure, the azo metal chelate dye of the present invention is considered to be an extremely stable recording material.

The valence of the metal forming the chelate is not particularly limited. In the case where the positive charge of the metal and the negative charge of the azo dye compound as the ligand are not balanced, an appropriate counter anion or cation may be prepared. However, the valence of the metal is preferably +2 in order to form a hexacoordinate octahedral complex with two ligands of the present application.
As the azo metal chelate dye of the present invention, a chelate compound comprising an azo dye compound represented by the general formula (2) and Ni is particularly preferable.
Examples of the method for forming the azo metal chelate dye of the present invention include a method of mixing a ligand and a metal salt in a solvent. In the chelate formation, the azo dye compound represented by the general formula (1) or the general formula (2) forms a chelate with a metal, so that protons are eliminated. The proton to be eliminated may be any proton in the structure of the azo dye compound, but a hydrogen atom at the amide site is preferred. If necessary, a base such as an amine or an alkoxide may be used to promote proton elimination.

The optical recording medium will be described below.
The optical recording medium to which this embodiment is applied contains an azo metal chelate dye composed of an azo dye compound represented by the general formula (1) and a metal in the recording layer. The configuration of the optical recording medium is not limited, but a layer configuration in which a substrate is usually provided and an undercoat layer, a reflective layer, a protective layer, or the like is provided as necessary may be used. As an example of a preferable layer configuration, for example, an optical recording medium in which a recording layer, a reflective layer, and a protective layer are provided on a substrate can be mentioned.

Hereinafter, the optical recording medium to which the present embodiment is applied will be described by taking the optical recording medium having such a layer structure as an example.
The substrate material in the optical recording medium to which the present embodiment is applied basically has only to be transparent at the wavelengths of recording light and reproducing light. For example, polycarbonate resins, vinyl chloride resins, acrylic resins such as polymethyl methacrylate, polystyrene resins, epoxy resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, polyimide resins, amorphous Polymer materials such as polyolefin and inorganic materials such as glass are used. It is preferable to use a polycarbonate resin from the viewpoints of high productivity, cost, moisture absorption resistance, and the like.

  These substrates are formed into a disk shape by injection molding or the like. If necessary, guide grooves and pits may be formed on the surface of the substrate. Such guide grooves and pits are preferably provided when the substrate is molded, but can also be provided on the substrate using an ultraviolet curable resin layer. When the guide groove is spiral, the groove pitch is preferably about 0.4 μm or more and 1.2 μm or less, particularly preferably about 0.6 μm or more and 0.9 μm or less.

  The groove depth is an AFM (Atomic Force Microscope) measurement value, and is usually 100 nm or more and 200 nm or less. In particular, in order to be able to record in a range from low speed 1X to high speed 8X or more, the groove depth is It is preferable to set it to about 150 nm or more and 180 nm or less. When the groove depth is larger than the above lower limit value, the degree of modulation tends to be obtained at a low speed, and when the groove depth is smaller than the above upper limit value, it is easy to ensure a sufficient reflectance. The groove width is a value measured by AFM (atomic force microscope) and is usually 0.20 μm or more and 0.40 μm or less. For high-speed recording applications, the groove width is more preferably 0.28 μm or more and 0.35 μm or less. When the groove width is larger than the above lower limit value, the push-pull signal amplitude is easily obtained. Further, the deformation of the substrate greatly affects the recording signal amplitude. For this reason, if the groove width is made larger than the lower limit, it becomes easy to suppress the influence of thermal interference and obtain good bottom jitter when recording at a high speed of 8 × or more. Furthermore, the recording power margin is widened and the tolerance for fluctuations in the laser power is increased, so that the recording characteristics and recording conditions are improved. When the groove width is smaller than the above upper limit value, thermal interference in the recording mark can be suppressed in low-speed recording such as 1X, and a good bottom jitter value can be easily obtained.

  Information such as address information, medium type information, recording pulse conditions, and optimum recording power can be recorded on the optical recording medium to which the present embodiment is applied. As a form for recording such information, for example, the LPP or ADIP format described in the DVD-R and DVD + R standards may be used.

  In the optical recording medium to which the present embodiment is applied, a recording layer containing the above-described azo metal chelate dye is formed on a substrate or, if necessary, an undercoat layer or the like. A recording layer containing such an azo metal chelate dye is required to have high sensitivity and high reflectance, but the recording layer containing the azo metal chelate dye of the present invention can satisfy this. In particular, it is possible to realize an optical recording medium capable of recording at a high speed of 8X or more, and a multilayer medium having two or more recording layers described later.

Conventionally, in order to obtain a recording layer compatible with high-speed recording (to increase the sensitivity of the dye), the absorption amount at the recording wavelength has been increased by increasing the absorption wavelength. However, such a method has a problem that although the amount of absorption increases, the reflectance decreases. In particular, a multilayer medium is more difficult because it requires a higher reflectance than a single layer medium.
On the other hand, if the recording layer containing the azo metal chelate dye of the present invention is used, both high sensitivity and high reflectance can be achieved. Since the azo metal chelate dye of the present invention has an extremely high extinction coefficient compared to conventional azo metal chelate dyes, the refractive index can be improved, so that it exceeds the decrease in reflectivity due to the longer absorption wavelength. It is thought that the reflectance is improved.
The azo metal chelate dye of the present invention can also be used for an optical recording medium capable of recording at 12X or more and 16X or more. In that case, combined use with another pigment | dye is preferable.

  As a method for forming a recording layer in an optical recording medium to which the present embodiment is applied, a thin film forming method that is generally performed such as a vacuum deposition method, a sputtering method, a doctor blade method, a casting method, a spin coating method, an immersion method, etc. Is mentioned. The spin coating method is particularly preferable from the viewpoint of mass productivity and cost.

In the case of film formation by spin coating, the rotation speed is preferably 500 rpm to 10,000 rpm. After spin coating, in some cases, treatment such as heating or solvent vapor may be performed. 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, or a dipping method may be any solvent that does not attack the substrate and is not particularly limited. Examples of the coating solvent include ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellosolv solvents such as methyl cellosolve and ethyl cellosolve; chains such as n-hexane and n-octane. Cyclic hydrocarbon solvents: Cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t-butylcyclohexane, cyclooctane; tetrafluoropropanol, octafluoropentanol, hexafluorobutanol, etc. Perfluoroalkyl alcohol solvents; hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate and methyl isobutyrate;
In the present invention, the content of the azo metal chelate dye of the present invention in the recording layer is not particularly limited as long as the effects of the present invention can be obtained, but is usually 0.1 to 100% by weight, preferably 10%. -100% by weight, more preferably 40-100% by weight.

  When forming the recording layer, an additive such as a quencher, an ultraviolet absorber, or an adhesive may be mixed with the above dye as necessary. Alternatively, substituents having various effects such as quencher effect and ultraviolet absorption effect can be introduced into the dye. Singlet oxygen quenchers added to improve the light resistance and durability of the recording layer include bisdithiols such as acetylacetonate, bisdithio-α-diketone and bisphenyldithiol, thiocatechol, and salicylaldehyde oxime. And metal complexes such as thiobisphenolate are preferred. Amine compounds are also suitable.

  Further, other dyes may be used in combination for improving the recording characteristics. Furthermore, the azo metal chelate dye to which the present embodiment is applied may be used in combination with a dye for low-speed recording so that both high-speed recording and low-speed recording can be achieved. However, the blending ratio is less than 60%, preferably 50% or less, more preferably 40% or less, based on the weight of the azo metal chelate dye. On the other hand, when the low-speed recording dye is used in combination, the blending ratio is usually 0.01% or more. When the blending ratio of the dye for low-speed recording is excessively large, the recording sensitivity necessary for high-speed recording of 8 × or more may not be sufficiently obtained. The azo metal chelate dye of the present invention may be used in combination with other high-speed recording dyes.

  Examples of the dye that can be used in combination include an azo dye compound of the same type as the azo dye compound represented by the general formula (1). In addition, the dyes that can be used in combination include azo dyes or azo metal chelate dyes, cyanine dyes, squarylium dyes, naphthoquinone dyes, anthraquinone dyes of the same type as the azo metal chelate dyes having the specific characteristics or structures described above. Dyes, porphyrin dyes, tetrapyraporphyrazine dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, triphenylmethane dyes, xanthene dyes, indanthrene dyes, indigo dyes, Examples include thioindigo dyes, merocyanine dyes, bispyromethene dyes, thiazine dyes, acridine dyes, oxazine dyes, indoaniline dyes, and other dyes. Examples of the dye thermal decomposition accelerator include metal compounds such as metal anti-knock agents, metallocene compounds, and acetylacetonato metal complexes.

  Furthermore, a binder, a leveling agent, an antifoaming agent, etc. can also be used together as needed. Preferable binders include polyvinyl alcohol, polyvinyl pyrrolidone, nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polystyrene resin, urethane resin, polyvinyl butyral, polycarbonate, polyolefin and the like.

  The film thickness of the recording layer (dye layer) is not particularly limited, but is preferably 10 nm or more and 300 nm or less. When the film thickness of the dye layer is larger than the lower limit, the influence of thermal diffusion can be suppressed, and good recording is easy. In addition, since the recording signal is hardly distorted, the signal amplitude can be easily increased. When the film thickness of the dye layer is smaller than the above upper limit value, it is easy to increase the reflectance and to improve the reproduction signal characteristics.

  The groove thickness of the recording layer is usually 30 nm or more and 180 nm or less, preferably 50 nm or more and 90 nm or less, and the film thickness between the grooves is usually 10 nm or more and 100 nm or less, preferably 30 nm or more and 70 nm or less. . When the groove film thickness or the groove film thickness is larger than the above lower limit value, the amplitude of the address information (LPP or ADIP) can be increased, and the occurrence of errors can be easily suppressed. When the groove film thickness or the groove film thickness is smaller than the above upper limit value, it is possible to suppress the influence of heat storage in the recording mark and the increase in crosstalk, and the bottom jitter tends to be good.

  The optical recording medium to which the present embodiment is applied has a reflectivity obtained by combining a recording layer containing an azo metal chelate dye having the specific characteristics or structure described above and a groove shape provided in the substrate. It can be 40% or more. For this reason, for example, a DVD-R that is reproduction-compatible with a DVD-ROM (there are two DVD-Rs and DVD + Rs in the standard, but these are hereinafter collectively referred to as DVD-R) can be realized. . The reflectance is measured with a disk player (for example, DVD player, DVD-ROM inspection machine, DVD drive) in which a laser having a wavelength range of 650 nm + 10 nm-5 nm is mounted on the pickup when tracking is performed on the groove of the optical disk. Say the reflectance.

  Next, a reflective layer having a thickness of 50 nm to 300 nm is preferably formed on the recording layer. As a material for the reflective layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, a metal of Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta and Pd is used alone or as an alloy. Is possible. Among these, Au, Al, and Ag have high reflectivity and are suitable as a material for the reflective layer. In particular, Ag and an Ag alloy are preferable because of their high reflectivity and high thermal conductivity. In addition to these metals, the following may be included. For example, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Mention may be made of metals such as Bi and metalloids. Among these, those containing Ag as a main component are low in cost, tend to improve reflectance when combined with an azo metal chelate dye, and have a ground when a print receiving layer described later is provided. This is particularly preferable from the viewpoint of obtaining a white and beautiful color. Here, the main component means one having a content of 50% or more. Since the azo metal chelate dye of the present invention has a small physical and chemical interaction with Ag, even if a reflective layer using Ag is used, the life (stability over time) of the optical recording medium is long. It is also possible to form a multilayer film by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal, and use it as a reflective layer.

  Examples of the method for forming the reflective layer include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition. In addition, a known inorganic or organic intermediate layer or adhesive layer may be provided on the substrate or under the reflective layer in order to improve reflectivity, improve recording characteristics, and improve adhesion.

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. For example, examples of the organic substance include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. Examples of the inorganic substance include SiO ₂ , SiN ₄ , MgF ₂ , SnO _{2 and the} like. A thermoplastic resin, a thermosetting resin, or the like can be formed by dissolving in an appropriate 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 a suitable solvent, and then applying the coating solution and curing it by irradiating with UV light. Examples of the UV curable resin include acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate. These materials may be used alone or in combination, and may be used not only as a single layer but also as a multilayer film.

  As a method for forming the protective layer, a coating method such as a spin coating method and a casting method, a sputtering method, a chemical vapor deposition method, and the like are used as in the recording layer. Among these, a spin coating method is preferable. The thickness of the protective layer is usually in the range of 0.1 μm or more and 100 μm or less. In the present embodiment, the thickness of the protective layer is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 20 μm or less.

  In addition, this Embodiment is not limited to said aspect, A various deformation | transformation can be carried out. For example, the optical recording medium may have two or more recording layers. Alternatively, a so-called dummy substrate having no groove on the reflective layer surface may be bonded, or two optical recording media facing each other with the reflective layer surfaces facing each other may be used. An ultraviolet curable resin, an inorganic thin film, or the like may be formed on the mirror surface side of the substrate in order to protect the surface and prevent the adhesion of dust. Furthermore, a print receiving layer can be further formed on a protective layer provided on the reflective layer or on a substrate bonded to the reflective layer surface.

(Multilayer media)
As an optical recording medium to which the present embodiment is applied, a multilayer medium having two or more recording layers can be preferably applied. The multilayer medium may be a medium that performs recording and reproduction by irradiating light from both sides of the optical recording medium, or a medium that performs recording and reproduction by irradiating light from one side of the optical recording medium. Especially, it can use suitably for the type of medium which records and reproduces by irradiating light from one side. This is because the recording layer containing the azo metal chelate dye of the present invention has high sensitivity and high reflectance.

The number of recording layers is not limited as long as the multilayer medium to which this embodiment is applied has two or more recording layers, but it is usually 2 to 5 layers, preferably 2 to 3 layers. The layer structure is not limited, but usually, each recording layer exists via another layer such as an intermediate layer. In addition, each recording layer preferably has a layer structure in combination with a reflective layer.
An example of the layer structure of a multilayer medium having two recording layers and recording and reproducing by irradiating light from one side is as follows: substrate / first recording layer / first reflective layer / intermediate layer / second recording A configuration of layer / second reflective layer / protective layer is exemplified, and other layers may be appropriately provided between these layers.

  The azo metal chelate dye of the present invention is preferably used for the recording layer (first recording layer) closest to the substrate. Since the dye of the present invention has a small amount of light absorption at the recording laser wavelength, when it is used for a recording layer close to the laser incident side, the light intensity transmitted to the recording layer on the far side relatively increases, As a result, a decrease in laser power required for recording on the far side layer can be reduced.

In the multilayer medium, the intermediate layer for interposing two or more recording layers may be composed of a single layer film or a multilayer film. The intermediate layer is usually made of a resin that is transparent and capable of forming a guide groove and has a high adhesive force. Furthermore, it is preferable to use a resin having a small shrinkage ratio at the time of curing and bonding because of high shape stability of the medium.
The intermediate layer is preferably made of a material that does not damage the adjacent recording layer. Examples of the material constituting the intermediate layer include curable resins such as thermoplastic resins, thermosetting resins, and radiation curable resins. In addition, the material of an intermediate | middle layer may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.
Among the materials for the intermediate layer, a radiation curable resin is preferable, and an ultraviolet curable resin is preferable among them. Examples of the ultraviolet curable resin include a radical (radical polymerization type) ultraviolet curable resin and a cationic (cation polymerization type) ultraviolet curable resin, both of which can be used.

  As the radical ultraviolet curable resin, for example, a composition containing an ultraviolet curable compound (radical ultraviolet curable compound) and a photopolymerization initiator as components is used. As a radical type ultraviolet curable compound, monofunctional (meth) acrylate and polyfunctional (meth) acrylate can be used as a polymerizable monomer component, for example. These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Here, acrylate and methacrylate are collectively referred to as (meth) acrylate.

  Although there is no restriction | limiting in a photoinitiator, For example, the thing of a molecular cleavage type or a hydrogen abstraction type is preferable. In the present invention, it is preferable to obtain an intermediate layer by curing an uncured ultraviolet curable resin precursor mainly composed of a radical polymerization type acrylic ester.

On the other hand, examples of the cationic ultraviolet curable resin include an epoxy resin containing a cationic polymerization type photoinitiator. Examples of the epoxy resin include bisphenol A-epichlorohydrin type, alicyclic epoxy, long chain aliphatic type, brominated epoxy resin, glycidyl ester type, glycidyl ether type, and heterocyclic type. As the epoxy resin, it is preferable to use a resin having a low content of free chlorine and chlorine ions. The amount of chlorine is preferably 1% by weight or less, more preferably 0.5% by weight or less.
Examples of the cationic polymerization type photoinitiator include sulfonium salts, iodonium salts, diazonium salts, and the like.

In the intermediate layer, a guide groove is usually formed in the same manner as the substrate described above. The shape of the guide groove formed on the substrate and the shape of the guide groove formed on the intermediate layer may be the same or different.
Although the film thickness of an intermediate | middle layer is not limited, Usually, it is 5 micrometers or more, Preferably it is 10 micrometers or more, and is 100 micrometers or less normally, Preferably it is 70 micrometers or less. The film thickness of the intermediate layer is desirably uniform.

There is no restriction | limiting in the formation method of an intermediate | middle layer, However, Usually, it forms as follows.
For the intermediate layer using a thermoplastic resin, a thermosetting resin, or the like, a coating solution is prepared by dissolving the thermoplastic resin or the like in an appropriate solvent. And an intermediate | middle layer can be formed by apply | coating this coating liquid and drying (heating).
On the other hand, an intermediate layer using a radiation curable resin can be formed by preparing a coating solution as it is or by dissolving in a suitable solvent, applying the coating solution, and irradiating and curing with a suitable radiation. it can.

In addition, there is no restriction | limiting in the coating method, For example, methods, such as coating methods, such as a spin coat method and a casting method, are used. Among these, the spin coat method is preferable. In particular, the intermediate layer using a high-viscosity resin can be applied and formed by screen printing or the like.
In the multilayer medium to which this embodiment is applied, the azo metal chelate dye of the present invention may be used in any recording layer.
In the present invention, the content of the azo metal chelate dye of the present invention in the multilayer recording layer is not particularly limited as long as the effects of the present invention can be obtained. It is 1 to 100% by weight, preferably 10 to 100% by weight, and more preferably 40 to 100% by weight.

  Recording on the optical recording medium obtained as described above is usually performed by irradiating a recording layer provided on both sides or one side of the substrate with laser light. In general, thermal deformation of the recording layer such as decomposition, heat generation, and melting due to absorption of laser light energy occurs in the portion irradiated with the laser light. The recorded information is normally reproduced by reading the difference in reflectance between a portion where thermal deformation has occurred and a portion where it has not occurred due to laser light.

  There is no particular limitation on the laser used for recording / reproducing, but for example, a dye laser capable of selecting a wavelength in a wide range of visible region, a helium neon laser having a wavelength of 633 nm, and a recently developed wavelength around 680 nm, 660 nm, 650 nm, and 635 nm. Examples include a high-power semiconductor laser, a blue laser near 400 nm, and a harmonic conversion YAG laser having a wavelength of 532 nm. Among these, a semiconductor laser is preferable in terms of lightness, ease of handling, compactness, cost, and the like. The optical recording medium to which the present embodiment is applied can perform high-density recording and reproduction at one wavelength or a plurality of wavelengths selected from these. The preferred wavelength range of the semiconductor laser for the azo metal chelate dye of the present invention is from 600 nm to 700 nm, more preferably from 630 nm to 680 nm, and even more preferably from 640 nm to 680 nm.

Hereinafter, the present embodiment will be specifically described by way of examples. However, this embodiment does not limit the present embodiment unless it exceeds the gist.
(Example 1)
(A) Compound production example (diazo coupling)
4.3 g of the compound represented by the structural formula 1b was dissolved in 11 ml of ethanol, and 3.5 g of acetic acid, 0.04 g of iodine and 2 g of the compound represented by the structural formula 1a were added. Further, 30% hydrogen peroxide solution dissolved in 11 ml of ethanol was added dropwise at room temperature. The precipitated solid was filtered and purified to obtain 1.7 g of an azo compound represented by the following structural formula 1c.

(Mounting)
1.6 g of the azo compound represented by the structural formula 1c was dissolved in 16 ml of tetrahydrofuran, and 0.44 g of nickel acetate tetrahydrate dissolved in 4 ml of methanol was added dropwise at room temperature. The precipitated solid was filtered and dried to obtain 1.5 g of an azonickel chelate dye.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 581 nm, the Gram extinction coefficient was 160 L / g · cm, and the absorption maximum wavelength of the coating film was 596 nm.

(B) Recording Example A 1.5% by weight TFP (2,2,3,3-tetrafluoro-1-propanol (hereinafter referred to as TFP)) solution of the azo metal chelate dye prepared as described above was added to a track pitch of 0. It spin-coated on the transparent polycarbonate substrate in which the guide groove | channel of 74 micrometers, groove depth 160nm, and groove width 0.32micrometer was formed, and it dried at 80 degreeC for 20 minutes. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm. On this recording layer, 120 nm of silver was sputtered, and then an ultraviolet curable resin was spin-coated with a thickness of 3 μm. Further, a transparent polycarbonate substrate having no groove was bonded after spin-coating an adhesive to produce an optical recording medium. did.

For this optical recording medium, a DVD-R Specification for General Ver. ERM plus modulation random signal recording with recording speed of 28.0m / s (equivalent to 8X of DVD-R: 8X) and shortest mark length of 0.4μm, using recording pulse strategy conditions compliant with 2.1 went.
Then, the signal of the recorded part was reproduced | regenerated at 3.5 m / s (equivalent to 1 time of DVD-R) using the same evaluation machine, and the bottom jitter (data to clock jitter) was measured. Further, the reflectance was measured as a value obtained by converting the voltage value output from the evaluation machine (the reflectance and the voltage are proportional). The bottom jitter value is preferably less than 9.0%, more preferably less than 8.0%. A higher reflectance is preferred.
As a result of the measurement, the 8X recording sensitivity was 34.0 mW, and the bottom jitter was good at 6.1%. Moreover, the reflectance was as high as 52%, which was good.

(Example 2)
The compound represented by Structural Formula 1b in Example 1 was changed to the following Structural Formula 2b and reacted in the same manner as in Example 1 to thereby react the azo nickel chelate of the azo compound represented by Structural Formula 2c and nickel. A dye was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 583 nm, the Gram extinction coefficient was 168 L / g · cm, and the absorption maximum wavelength of the coating film was 598 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 34.0 mW, the bottom jitter at the time of 1X reproduction was 6.2%, and the reflectance was 52%.

(Example 3)
The compound represented by the structural formula 1b in Example 1 was changed to the following structural formula 3b and reacted in the same manner as in Example 1, whereby an azo nickel chelate of the azo compound represented by the following structural formula 3c and nickel. A dye was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 584 nm, the Gram extinction coefficient was 165 L / g · cm, and the absorption maximum wavelength of the coating film was 598 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 33.0 mW, the bottom jitter during 1X reproduction was 6.3%, and the reflectance was 50%, which was a favorable result.

Example 4
The compound represented by Structural Formula 1b in Example 1 was changed to the following Structural Formula 4b and reacted in the same manner as in Example 1, whereby an azonickel chelate of an azo compound represented by Structural Formula 4c and nickel was used. A dye was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 586 nm, the gram extinction coefficient was 161 L / g · cm, and the absorption maximum wavelength of the coating film was 600 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 34.0 mW, the bottom jitter during 1X reproduction was 6.1%, and the reflectance was 51%, which were good results.

(Example 5)
The compound represented by Structural Formula 1a in Example 1 is changed to the following Structural Formula 5a, the compound represented by Structural Formula 1b in Example 1 is changed to Structural Formula 2b, and reacted in the same manner as in Example 1. Thus, an azo nickel chelate dye of an azo compound represented by the following structural formula 5c and nickel was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 579 nm, the Gram extinction coefficient was 205 L / g · cm, and the absorption maximum wavelength of the coating film was 598 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 36.0 mW, the bottom jitter at the time of 1X reproduction was 6.0%, and the reflectance was 54%.

(Example 6)
The compound represented by the structural formula 1a in Example 1 is changed to the following structural formula 6a, the compound represented by the structural formula 1b in Example 1 is changed to the structural formula 2b, and reacted in the same manner as in Example 1. As a result, an azo nickel chelate dye of an azo compound represented by the following structural formula 6c and nickel was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 582 nm, the Gram extinction coefficient was 185 L / g · cm, and the absorption maximum wavelength of the coating film was 597 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 38.0 mW, the bottom jitter during 1X reproduction was 6.5%, and the reflectance was 51%, which were good results.

(Example 7)
By changing the compound represented by Structural Formula 1a in Example 1 to Structural Formula 6a, changing the compound represented by Structural Formula 1b in Example 1 to Structural Formula 4b, and reacting in the same manner as in Example 1 Then, an azo nickel chelate dye of an azo compound represented by the following structural formula 7c and nickel was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 586 nm, the Gram extinction coefficient was 183 L / g · cm, and the absorption maximum wavelength of the coating film was 600 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 38.0 mW, the bottom jitter during 1X reproduction was 6.4%, and the reflectivity was 50%, which were good results.

(Comparative Example 1)
The compound represented by Structural Formula 2b in which the compound represented by Structural Formula 1a in Example 1 was changed to the compound represented by Structural Formula 8a below, and the compound represented by Structural Formula 1b in Example 1 was used in Example 2 And an azo nickel chelate dye of an azo compound represented by the following structural formula 8c and nickel was obtained by reacting in the same manner as in Example 1.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 568 nm, the Gram extinction coefficient was 180 L / g · cm, and the absorption maximum wavelength of the coating film was 585 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction was performed on this disc under the same conditions as in Example 1. At this time, the 8X recording sensitivity was 43.0 mW, the bottom jitter during 1X reproduction was 6.5%, and the reflectance was 50%. Although the reflectivity and the bottom jitter were good, the recording sensitivity was poor compared to the examples.

(Comparative Example 2)
In the same manner as in Example 1, the compound represented by Structural Formula 1a in Example 1 was changed to the following Structural Formula 9a, the compound represented by Structural Formula 1b in Example 1 was changed to the following Structural Formula 9b. By reacting, an azo nickel chelate dye of an azo compound represented by the following structural formula 9c and nickel was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 522 nm, the Gram extinction coefficient was 146 L / g · cm, and the absorption maximum wavelength of the coating film was 561 nm.

An optical recording medium was prepared under the same conditions as in Example 1 except that the above dye was used. This recording layer had a groove thickness of 40 nm and a groove thickness of 85 nm, which was almost the same as the dye of Example 1.
Next, recording / reproduction of this disk was attempted under the same conditions as in Example 1. However, even if 55 mW, which is the upper limit power of the tester, was applied, recording at 8X was not possible at all. Therefore, when only the reflectance was measured, it was 60%.

  The results in Examples 1 to 7 and Comparative Examples 1 and 2 are shown in Table 1. From the results shown in Table 1, it can be seen that Examples 1 to 7 are excellent in recording sensitivity as compared with Comparative Example 1 and Comparative Example 2.

(Example 8)
A two-layer medium was prepared and the recording characteristics of Layer 0 were evaluated. Here, Layer0 means a recording layer (first recording layer) closer to the substrate, and Layer1 means a recording layer (second recording layer) far from laser incidence.
Layer 0 is a mixture of the azo nickel chelate dye represented by the structural formula 2c and the azo zinc chelate dye of the following structural formula 10c and zinc mixed at 50:50 (weight ratio). Using. As Layer 1, an azo zinc chelate dye of an azo compound represented by the following structural formula 10c and zinc was used.

Further, AgBi _1.0 alloy is formed with a thickness of 20 nm as the first reflective layer, Ag is formed with a thickness of 120 nm as the second reflective layer, and an ultraviolet curable resin is formed with a thickness of 50 μm as the intermediate layer. did. The track pitch was 0.74 μm, the groove depth was 170 nm, and the groove width was 0.31 μm. Layer 0 groove thickness was 30 nm and groove thickness was 70 nm. In addition, Layer 1 has a groove thickness of 35 nm and a groove thickness of 75 nm.

A recording speed of 46.1 m / s (DVD + R) was applied to the optical recording medium using a recording pulse strategy condition in accordance with DVD + R 8.5 Gbytes Basic Format Specification version 1.1 with a recording / reproducing apparatus having a wavelength of 650 nm and a numerical aperture of 0.65. EFM plus modulation random signal recording with a shortest mark length of 0.44 μm was performed. Thereafter, the signal of the recorded part was reproduced at 3.84 m / s using the same evaluator, and the bottom jitter (data to clock jitter) was measured.
As a result of the evaluation, the 12X recording sensitivity of Layer 0 was 53.0 mW, the bottom jitter during 1X reproduction was 7.5%, and the reflectance was 17%, which was a favorable result.

  ADVANTAGE OF THE INVENTION According to this invention, the azo metal chelate pigment | dye and optical recording medium suitable for the optical recording medium which can record at high speed, and the recording layer of the optical recording medium which has a recording layer in multiple layers are provided.

Claims (7)

An azo metal chelate dye comprising an azo dye compound represented by the following general formula (1) and a metal.

(In the general formula (1), R ₁ is an optionally substituted linear or branched alkyl group or an optionally substituted cycloalkyl group. R ₂ and R ₃ are each independently R ₄ , R ₅ , R ₆ , R ₇ are a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group. And R ₈ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R ₄ and R ₅ , R ₄ and R _6, R ₅ and R ₇ are bonded to each other Y may be a linear or branched alkyl group substituted with at least two fluorine atoms, and a proton is eliminated from the compound of the general formula (1). Chelate dye is composed of metal.)   The azo metal chelate dye according to claim 1, wherein the metal is any one of Ni, Co, Cu, and Pd. An azo metal chelate dye comprising an azo dye compound represented by the following general formula (2) and Ni.

(In General Formula (2), R ₁₁ is an optionally substituted linear or branched alkyl group or an optionally substituted cycloalkyl group. R ₁₂ and R ₁₃ are each independently, R ₁₄ is a hydrogen atom, an optionally substituted linear or branched alkyl group, an optionally substituted aryl group, or an optionally substituted heterocyclic group, and R ₁₄ is an optionally substituted R _{15 to} R ₂₀ each independently represents a hydrogen atom or an optionally substituted straight chain or branched alkyl group, from the compound of the above general formula (2) to a proton. The chelate dye is composed of the metal from which the is desorbed and the metal.) In the general formula (2), R ₁₁ is a linear or branched alkyl group having 1 to 4 carbon atoms, R ₁₂ is an unsubstituted or halogen-substituted alkyl group or aryl group, R ₁₃ is a hydrogen atom, and R ₁₄ is carbon number. 4. The azo metal chelate dye according to claim 3, wherein the linear alkyl group having 1 to 6 or the branched alkyl group having 3 to 8 carbon atoms and R _{15 to} R ₂₀ are hydrogen atoms.   An optical recording medium comprising a recording layer containing the azo metal chelate dye according to any one of claims 1 to 4.   6. The optical recording medium according to claim 5, wherein the optical recording medium has two or more recording layers, and at least one recording layer contains the azo metal chelate dye.   7. The optical recording medium according to claim 5, wherein recording at 8 times speed or higher is possible.