JPH1112483A - Metal chelate compound and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal chelate compd. which has improved light and heat stability by forming it from an azoic compd. and a metal. SOLUTION: This metal chelate compd. is formed from an azoic compd. of formula I and a transition metal (e.g. Ni or Co). In the formula, A is a residue which, together with carbon and nitrogen atoms bonded thereto, forms a heterocycle; ring B is arom.; X is an active hydrogen group; and R is alkyl or aryl. The heterocycle-forming residue is represented by formula II, wherein ring D may be substd. by 1-6C alkyl, alkoxy, etc.; and Q is H, 1-6C alkyl, cyano, nitro, halogen, etc. The optical recording medium comprises a transparent substrate (e.g. a plastic), a recording layer having a thickness of 10-5,000 nm and contg. the metal chelate compd., a reflection layer having a thickness of 50-200 nm and reflecting light coming through the substrate, and a protective layer formed on the reflection layer. Writing and/or reading information with a laser is done at the recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal chelate compound and an optical recording medium, and more particularly to a novel metal chelate compound having excellent light stability and heat stability, and an optical recording medium containing the metal chelate compound in a recording layer. About.

[0002]

2. Description of the Related Art An optical recording medium (optical disk) on which information can be written and / or read by a laser has a larger recording capacity and a random access than conventional recording media. It is used as a recording medium in fields such as computer software, game software, and electronic publishing. In particular, a write-once compact disc (CD-WO) shows the same reflectance as a read-only compact disc, so that after recording,
It has the characteristic that it can be played back on a read-only compact disc player or drive.

For example, in the above-mentioned CD-WO, usually, a light absorbing layer made of an organic dye, a light reflecting layer made of a metal, and a protective layer made of an ultraviolet curable resin are sequentially formed on a transparent substrate having a guide groove (groove). Is provided. Then, the recording is performed by a dedicated recorder at 1.2 to 1.4 m / sec.
c range, or twice the speed of any speed within the range, 4
This is performed as follows while rotating the disk at a constant speed such as double speed or six times speed. That is, a servo is applied to the groove, and a recording pit is formed by using a laser beam narrowed down to about 1 μm and deforming or altering the light absorbing layer and the layer adjacent thereto in the heat mode.

Heretofore, many proposals have been made on the above organic dyes, in addition to phthalocyanine dyes and cyanine dyes, as well as complexes of monoazo compounds with metals. However, each of the above dyes cannot sufficiently satisfy sensitivity, storage stability, light fastness, and spin coating properties. The present applicant has previously proposed a metal chelate compound of an azo compound represented by a specific general formula and a metal as an organic dye satisfying the above properties (Japanese Patent Laid-Open No. 6-655).
No. 14).

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metal chelate compound having improved light stability (light resistance) and heat stability, and an optical recording medium containing the metal chelate compound in a recording layer. Is to do.

[0006]

As a result of various studies, the inventors of the present invention have developed a novel azo compound disclosed in JP-A-6-65514, which is structurally improved to introduce an aryl group. It has been found that the azo compound can easily achieve the above object.

The present invention has been completed based on the above findings, and a first gist thereof lies in a metal chelate compound comprising an azo compound represented by the following general formula (I) and a metal.

[0008]

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In the general formula (I), A represents a residue forming a heterocyclic ring together with the carbon atom and nitrogen atom to which it is bonded, ring B represents an optionally substituted aromatic ring, X Represents a group having an active hydrogen, and R represents an optionally substituted alkyl group or an optionally substituted aryl group.

A second aspect of the present invention is to provide an optical recording medium having a recording layer on at least one surface of a light-transmitting substrate, on which information can be written and / or read by a laser. An optical recording medium comprising a metal chelate compound comprising an azo compound represented by the general formula (I) and a metal.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
First, the metal chelate compound of the present invention will be described.
The metal chelate compound of the present invention comprises the azo compound represented by the general formula (I) and a metal.

In the above general formula (I), A represents a residue which forms a heterocyclic ring together with the carbon atom and nitrogen atom to which it is bonded, and specific examples thereof include the following general formula: Heterocyclic-forming residues as shown in (a) to (i).

[0013]

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In the above general formulas (a) to (i), the ring D may be substituted, and the substituent may be an alkyl group, an alkoxy group, a halogen atom, an alkylsulfonyl group, an alkylcarbonyl group, a formyl group. Group, nitro group, trifluoromethyl group, trifluoromethoxy group, cyano group, alkylthio group and the like. In addition, the carbon number of alkyl in these composite groups is usually 1 to 6.
In the general formulas (a) to (i), Q represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyalkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, or a halogen atom. .

In the general formula (I), X represents a group having active hydrogen, and specific examples thereof include -NH ₂ , -B
_{(OY) 2, -OY, -COOY} , -SO 3 Y, -NYS
O ₂ Z (where Y represents a hydrogen atom or a cation, and Z represents a linear or branched alkyl group having 1 to 6 carbon atoms which may be substituted) and the like.

In the general formula (I), examples of the substituent on the ring B include the same substituents as those on the ring D in the general formulas (a) to (i).

In the general formula (I), R represents an alkyl group which may be substituted or an aryl group which may be substituted, and these substituents are the same as those in the ring D described above. Substituents. Examples of the alkyl include an alkyl group having 1 to 6 carbon atoms, and examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group.

In the present invention, preferred azo compounds are compounds represented by the following general formula (II).

[0019]

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In the general formula (II), A and X have the same meanings as A and X in the general formula (I), and R1 and R2 each represent a linear or branched alkyl group having 1 to 6 carbon atoms.

Specific examples of the azo compound in the present invention are as shown in the following formulas (1) to (10).

[0022]

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[0023]

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In the present invention, the metal forming the chelate compound with the azo compound is not particularly limited as long as it is generally a metal capable of forming the chelate compound with the azo compound. , R
Transition metals such as u, Rh, Pd, Os, Ir, and Pt, and more preferably Ni or Co.

The general synthesis of the metal chelate compounds of the present invention is described, for example, in Furukawa; Analytica Chemical.
a Acta 140 (1982) 281-289. For example, the case of the metal chelate compound composed of the azo compound shown in the above (1) will be described as follows.

First, an amino compound represented by the following formula (III) is diazotized according to a conventional method,
The azo compound shown in the above (1) is obtained by coupling with a phenol compound represented by the following formula, and then the azo compound is reacted with a metal salt in water and / or an organic solvent.

[0027]

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The phenol compound represented by the above formula (IV) can be easily obtained according to the following reaction route.

[0029]

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In the reaction between the azo compound and the metal salt,
Solvents include, for example, methanol, ethanol,
Seton, dioxane, tetrahydrofuran, etc. are used.
And as the anion of the metal salt, for example,
SCN^-, SbF ₆ ^-, Cl^-, Br^-, F^-, Cl
O _Four ^-, BF_Four ^-, PF ₆ ^-, CH_ThreeCOO^-, Ti
F ₆ ^2-, SiF ₆ ^2-, ZrF ₆ ^2-, Ph-SO _Three ^-, C
H_Three-Ph-SO _Three ^-, B^--(Ph)_FourEtc. monovalent or
A divalent anion is used. Among these,
CH_ThreeCOO^-Is preferred. In the above equation, Ph is a base.
Represents a Zensen ring.

Next, the optical recording medium of the present invention will be described. The optical recording medium of the present invention is basically a recording layer (B) containing a translucent substrate (A) and a metal chelate compound comprising a metal and an azo compound represented by the general formula (I). It is composed of The recording layer (B) is usually provided on one surface of the light-transmitting substrate (A), but may be formed on both surfaces of the light-transmitting substrate (A) for higher recording density. Then, writing and / or reading of information with a laser is performed by the recording layer (B).

In the optical recording medium of the present invention, an undercoat layer can be provided on the surface of the light-transmitting substrate (A), if necessary. A preferred embodiment of the present invention is an optical recording medium in which a reflective layer (C) for reflecting light transmitted through a light-transmitting substrate is formed on a recording layer (B). In the case of such an optical recording medium, usually, a protective layer (D) is provided on the surface of the reflective layer.

As the light-transmitting substrate (A), glass and plastic can be mentioned, but plastic is preferably used. As such a plastic, a polycarbonate resin is preferably used. The reflection layer (C) is usually
It is composed of metals such as gold, silver and aluminum,
It is preferred to be composed of silver. In addition, the protective layer (D)
Is not particularly limited, and various ultraviolet curable resins are appropriately used.

The formation of the recording layer (B) is usually carried out by a spin coating method of a coating solution containing a metal chelate compound comprising an azo compound represented by the general formula (I) and a metal. In preparing the coating solution, a binder can be used as necessary. Such binders include polyvinyl alcohol, polyvinyl pyrrolidone,
Ketone resin or the like is used. Examples of the coating solvent include ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolve solvents such as methyl cellosolve and ethyl cellosolve, and perfluoro solvents such as tetrofluoropropanol and octafluoropentanol. Alkyl alcohol solvents, hydroxyethyl solvents such as methyl lactate and methyl isobutyrate are preferably used.

The recording layer (B) is composed of a metal chelate compound comprising an azo compound represented by the general formula (I) and a metal, and has excellent light stability (light resistance) and heat stability. However, in order to further improve these characteristics, the recording layer (B) may contain a transition metal chelate compound as a singlet oxygen quencher. Such transition metal chelate compounds include, for example, acetylacetonate,
Bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone and the like can be mentioned.

On the other hand, the reflection layer (C) is formed by a sputtering method using a target material made of the above-mentioned metal.

Usually, the thickness of the recording layer (B) is from 10 to 500
0 nm, and the thickness of the reflection layer (C) is 50 to 200 nm.

In the optical recording medium of the present invention having a reflective layer, writing (recording) and / or reading (reproduction) of information is performed by a laser beam converged to about 1 μm. That is, recording is performed by melting, evaporation, sublimation, deformation, denaturation, or the like occurring in the laser beam irradiated portion (recording portion) of the recording layer. Reproduction is performed by reading the difference in reflectance between the laser light irradiated part and the non-irradiated part by using the laser light. As the laser light, a semiconductor laser light is preferably used.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 (Production of metal chelate compound) 1.5 g (13.1 mmol) of 2-amino-4-methylthiazole represented by the above formula (III) was added to a mixed solution of 3 ml of acetic acid and 7 ml of concentrated sulfuric acid. Then, 11 m of water was added, and the mixture was stirred with ice cooling. Then, sodium nitrite 910m
g (13.2 mmol) was dissolved in 5 ml of water. Then, the above solution was gradually dropped into an aqueous solution of sodium nitrite under ice cooling to obtain a diazotized solution. On the other hand, 3.8 g (13.1 mmol) of 3- (N, N-di- (4-methyl) phenylamino) phenol represented by the formula (IV) in a mixed solvent of acetic acid: methanol (1: 2) 210 ml. Was dissolved and cooled to 5 ° C.

The above diazotized solution was gradually dropped into the above phenol solution under vigorous stirring to carry out a coupling reaction. After completion of the reaction, the reaction solution was neutralized with an aqueous sodium hydroxide solution, and the organic layer was extracted with chloroform and water. Next, the obtained organic layer is washed with water, and the solvent is distilled off. The residue is separated into individual products by column chromatography (silica gel, developing solvent: 0.5% ethyl acetate / chloroform). After crystallization, the above formula (1)
602 g of a brown crystalline diazo compound shown in the following was obtained. The yield was 32%. Λ _max (in methanol) of this compound was 512 nm, and the NMR measurement results were as follows.

¹ H NMR (300 MHz, CDCl / T
MS): d (ppm): 7.20 (d, 4H, J = 8.
46 Hz, ArHe), 7.13 (t, 1H, J = 4.
41 Hz, ArHd), 6.46 (d, 1H, J = 9.
18 Hz, ArHb), 6.44 (d, 1H, J = 2.
22Hz, ArHa), 6.21 (dd, 1H, J =
9.36, 2.40 Hz, ArHe), 3.97 (s,
_{3H, CH 3), 2.37 (} s, 6H, C 6 H 4 CH 3)

Next, 100 mg of the above diazo compound was dissolved in 25 ml of ethanol, and NiCl 2 .6H 2 O 3.
After adding 812 g (4 ml of an aqueous solution of water),
Stir for 15 minutes. Thereafter, the solvent was distilled off under reduced pressure, and the precipitated crystals were separated by filtration to obtain 67 mg of a brown nickel chelate compound. The λ _max (in chloroform) of this compound was 614 nm (ε = 6.3 × 10 ⁴ ). FIG. 1 shows the visible absorption spectrum of this compound in a chloroform solution.

Example 2 (Production of Optical Recording Medium) 0.15 g of the metal chelate compound obtained in Example 1 was dissolved in 7.5 g of otafluoropentanol, and 0.22 μm
To obtain a solution. Then the depth 70
The solution was dropped onto an injection-molded polycarbonate resin substrate (diameter: 5 inches) having a groove of 0 ° and a width of 0.7 μm, and the solution was applied by a spin coating method at a rotation speed of 500 rpm. After the application, it was dried at 60 ° C. for 10 minutes. The maximum absorption wavelength of the coating film was 631 nm. FIG. 2 shows the absorption spectrum of the coating film.

Next, a silver film having a thickness of 2000 ° (200 nm) was formed on the above-mentioned coating film by a sputtering method to form a reflection layer. Then, a UV-curable resin was spin-coated on the reflective layer and then cured to form a protective layer having a thickness of 10 μm (10000 nm), thereby obtaining an optical disk of the present invention.

While rotating the optical disk at 1.4 m / s, a semiconductor laser beam having a center wavelength of 780 nm was irradiated at a recording power of 6.6 mW to record an EFM signal.
Thereafter, the recording section was reproduced by a CD player equipped with a semiconductor laser having the same wavelength as the above, and as a result, a good reproduction signal was obtained.

The above optical disk was tested for light resistance (xenon fade meter acceleration test: 60 hours) and storage stability (70 ° C., 85% RH: 500 hours). No deterioration of the reproduced signal was observed, and the optical disk was excellent.

[0048]

According to the present invention described above, a metal chelate compound having further improved light stability (light resistance) and thermal stability and an optical recording medium containing the metal chelate compound in a recording layer are provided.

[Brief description of the drawings]

FIG. 1 is a visible absorption spectrum of a metal chelate compound according to Example 1 in a chloroform solution.

FIG. 2 is a visible absorption spectrum of a coating film of a metal chelate compound according to Example 1.

Claims (6)

[Claims] 1. A metal chelate compound comprising an azo compound represented by the following general formula (I) and a metal. Embedded image (In the general formula (I), A is a residue which forms a heterocyclic ring together with the carbon atom and the nitrogen atom to which it is bonded,
Ring B represents an optionally substituted aromatic ring, X represents a group having active hydrogen, and R represents an optionally substituted alkyl group or an optionally substituted aryl group. ) 2. The metal chelate compound according to claim 1, wherein the azo compound is a compound represented by the following general formula (II). Embedded image (In formula (II), A has the same meaning as A in formula (I), _{X, -NH 2, -B (OY)} 2, -OY, -
_{COOY, -SO 3 Y, -NYSO 2} Z ( where, Y represents a hydrogen atom or a cation, Z is optionally substituted good having 1 to 6 carbon atoms straight-chain or branched alkyl group), R1 and R2 are Represents a linear or branched alkyl group having 1 to 6 carbon atoms. ) 3. An optical recording medium in which a recording layer on which information can be written and / or read by a laser is provided on at least one surface of a translucent substrate, wherein the recording layer is represented by the general formula (I). An optical recording medium comprising a metal chelate compound comprising an azo compound and a metal. 4. The optical recording medium according to claim 3, wherein the azo compound is a compound represented by the general formula (II). 5. The optical recording medium according to claim 3, wherein a reflection layer for reflecting light transmitted through the light-transmitting substrate is formed on the recording layer. 6. The optical recording medium according to claim 5, wherein the reflection layer is made of silver.