JPH10134413A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve the light resistance of org. dyestuff by combining the nitrosodiphenyl amine deriv. and bisphenyl dithiol complex having specific chemical formulas as additives to a recording layer having the org. dyestuff. SOLUTION: The optical recording medium which has the recording layer contg. the org. dyestuff on a substrate and to and from which information is recorded and reproduced by photoirradiatiom contains the nitrosodiphenyl amine deriv. and bisphenyl dithiol deriv. in the recording layer. The compd. expressed by [formula I] (where; R<2> is an alkyl group, etc.) is used as the nitrosodiphenyl amine deriv. and the compd. expressed by [formula II] (where, R<1> is an alkyl group, etc., M is a transition metal) is used as the bisphenyl dithiol complex. The compd. expressed by the [formula II] well acts as the singlet oxygen quencher of the recording layer formed by using the org. dyestuff as the compd. is used in combination with the nitrosodiphenyl amine deriv. expressed by the [formula I].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a recording layer containing an organic dye, and more particularly, to a high-sensitivity write-once optical recording medium having excellent light resistance and storage stability.

[0002]

2. Description of the Related Art In recent years, with the development of information technology, an optical recording medium which is a small and large-capacity recording medium has been used. Such optical recording media are classified into read-only media such as CDs (compact discs) and DVDs, write-once recording media that can be written only once, and rewritable media represented by magneto-optical discs. Among these, a write-once recording medium using an organic dye for the recording layer is known.

Japanese Patent Application Laid-Open No. 2-168446 discloses a write-once type CD having a high reflectance and capable of obtaining an output signal conforming to the CD format for information reproduction, that is, a CD-R (Compact Disc Recordable). ) Is disclosed. This write-once CD has a structure in which a recording layer composed of an organic dye, a reflective layer, and a protective layer are sequentially laminated on a substrate surface on which a preformat pattern is formed. Irradiating the recording layer with laser light, the thermal energy of the laser light alters the organic dyes that make up the recording layer and changes their optical characteristics, and also deforms a part of the transparent substrate that is the base of the recording section. Make a record.

A cyanine dye is known as an organic dye used in the recording layer of the write-once type optical recording medium as described above (Japanese Patent Application Laid-Open No. 58-112790, etc.).

[0005]

However, the cyanine dye layer is generally liable to be degraded by light such as sunlight or a reproduction laser. Causes of this deterioration include autoxidation and cleavage of the dye molecules by ultraviolet rays, but mainly in the organic dye layer, oxygen is excited to a singlet electronic state, and this singlet oxygen is unsaturated in the dye molecules. It is thought to be due to reacting with the group. An optical recording medium in which a singlet oxygen quencher is added to the recording layer to improve the light resistance of the organic dye constituting the recording layer has been proposed in JP-A-59-55795 and the like. Not enough yet.

[0006] In Japanese Patent Application Laid-Open No. 2-300288,
A technique for improving the light fastness and storage stability of an optical recording medium by including a nitrosodiphenylamine derivative as a deterioration inhibitor in an organic dye material of the optical recording medium has been disclosed, but the light fastness was not sufficient. .

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an organic dye recording excellent in light resistance and storage stability in an optical recording medium for recording / reproducing using laser light. An object of the present invention is to provide an optical recording medium having a layer.

[0008]

Means for Solving the Problems The present inventors have intensively studied and examined additives for improving the light fastness of a dye in a recording layer, particularly a cyanine dye, and found that a nitrosodiphenylamine derivative and a bisphenyldithiol complex were used. It has been found that when used in combination in the recording layer, the light resistance is remarkably improved.

That is, according to the present invention, a recording layer containing an organic dye is provided on a substrate, and information is recorded / recorded by light irradiation.
The optical recording medium to be reproduced is provided, wherein the recording layer contains a nitrosodiphenylamine derivative and a bisphenyldithiol complex in a recording layer.

As the nitrosodiphenylamine derivative, a compound represented by the following general formula (1) is preferred. When the compound represented by the general formula (1) is used in combination with a bisphenyldithiol complex described later, it works particularly well as a singlet oxygen quencher containing a recording layer containing an organic dye.

[0011]

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In the formula, R ² represents a hydrocarbon group, a hydrogen atom or a halogen atom. When R ² is a hydrocarbon group, for example, an alkyl group such as a methyl group, and an aromatic hydrocarbon group such as a dialkylamino group and an aryl group are preferable.

As the above bisphenyldithiol complex,
Compounds represented by the following general formula (2) are preferred. The compound represented by the general formula (2) works particularly well as a singlet oxygen quencher in a recording layer using an organic dye when used in combination with the nitrosodiphenylamine derivative represented by the aforementioned general formula (1). I will do it.

[0014]

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In the formula, R ¹ may be the same or different and represents a hydrocarbon group or hydrogen. When R ¹ is a hydrocarbon group, it can be, for example, an alkyl group such as a methyl group or an aromatic hydrocarbon group such as an aryl group. In the formula, M is N
Indicates transition metals such as i and Fe.

As the organic dye contained in the recording layer, a cyanine dye, a phthalocyanine dye, a naphthalocyanine dye, an azulenium dye, a naphthoquinone dye, and an anthraquinone dye can be used. In the present invention, a cyanine dye is preferable. It is. As the cyanine dye, a cyanine compound represented by the following general formula (3) is particularly preferable as a recording layer of a write-once optical recording medium.

[0017]

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In the formula, R ³ may be the same or different and represents an alkyl group, an annealing group, a dialkylamino group, a hydrogen atom or a halogen atom. When R ³ is a hydrocarbon, it can be, for example, an aromatic hydrocarbon group such as a methyl group, an alkyl group, and an aryl group. In the formula, X ⁻ represents an anion, a halogen ion such as I ⁻ , Cl ⁻ , ClO ^4- , BF
^{4- and the} like. In the formula, Z and Z ′ each represent an aromatic group;
Cyanine dyes having an aromatic group represented by the following formulas (a) to (f) are particularly preferable as a recording layer of a write-once optical recording medium. In the formula, Z and Z ′ may be the same or different.

[0019]

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In the formula, R ′ may be the same or different and represents an alkyl group, an anneal group, a dialkylamino group, a hydrogen atom or a halogen atom. Where Y is S, C
(CH ₃ ) ₂ , O, Se and the like.

The reason why the light fastness of the cyanine dye is remarkably improved by adding a nitrosodiphenylamine derivative and a bisphenyldithiol complex to the recording layer at present is not clear, but these additives are incompatible with the cyanine dye. This is considered to be due to the fact that the cyanine dye is electrically coupled and thereby stabilized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments and examples of the optical recording medium of the present invention will be specifically described with reference to the drawings, but the present invention is not limited thereto.

FIGS. 1 and 2 are a sectional view and a plan view, respectively, of a main part of a write-once optical recording medium according to the present invention. The optical recording medium 10 has a transparent substrate 1 on which a preformat pattern is formed as prepits 6 and guide grooves 5 on one side, a dye layer (recording layer) 2 formed on the preformat pattern surface of the transparent substrate 1, and a dye layer 2. A reflective layer 3 laminated thereon;
It basically comprises a protective layer 4 on the reflective layer 3.

The transparent substrate 1 is made of, for example, polycarbonate, polymethine methacrylate, polymethylpentene,
By injection molding a transparent resin material such as epoxy,
Alternatively, a method of forming a replica layer of a photocurable resin on one surface of a transparent ceramic plate such as glass (so-called
It is formed into a disk shape having a center hole 7 at the center by P method). The transparent substrate 1 can be manufactured by using any known method without being limited to the above-described manufacturing method. In the following examples, a polycarbonate substrate 1 was used.

As shown in the plan view of FIG. 2, the preformat pattern includes a guide groove 5 for making a recording / reproducing laser beam follow, a recording track 8 determined by the guide groove 5, an address and a reference clock. The pre-pit 6 shown in FIG. The guide groove 5 is formed in a spiral or concentric shape concentric with the center of the center hole 7. Various information can also be detected from the wobble by using the guide groove as a wobble groove. Further, the guide groove 5 and the pre-pit 6 can be formed at different depths.

The dye layer 2 includes a dye such as a cyanine dye,
In addition to a mixture of a nitrosodiphenylamine derivative and a bisphenyldithiol complex, a singlet oxygen quencher,
A deterioration inhibitor such as an ultraviolet absorber, an infrared absorber, an antioxidant, and a reducing agent may be added. Further, a resin such as an acrylic resin, a polycarbonate resin, a polyester resin, or polyvinyl alcohol may be added as needed. The dye layer 2 can be formed by a dry process such as vacuum deposition or sputtering. A mixture of the cyanine dye, the nitrosodiphenylamine derivative, and the bisphenyldithiol complex of the present invention can be formed using an alcohol such as methanol or ethanol, methylcell, or the like. It is more preferable to use a wet process of dissolving 1 to 10% in a solvent of a cell solvent such as Solve, ethyl cell solvent or the like, or a ketone solvent such as acetone or methyl ethyl ketone and forming a film by a spin coating method. The components of the dye layer are composed of 60 to 90% by weight of a cyanine dye, 1 to 39% by weight of a nitrosodiphenylamine derivative, and 1 to 1% of a bisphenyldithiol complex.
Desirably, it is 39% by weight. The thickness of the dye layer is 30
0-3000A (angstrom) is preferable, and 500-2000A is more preferable.

The reflective layer 4 can be made of any reflective material such as gold, silver, copper, and aluminum, or an alloy containing these materials as a main component.

The protective layer 5 can be made of an inorganic material such as SiO, SiN or AlN, or an organic material such as a photocurable material.

Example 1 12 parts by weight of a cyanine dye represented by the following structural formula (4):
A mixed solvent of 4 parts by weight of a nitrosodiphenylamine derivative represented by the following structural formula (5) and 4 parts by weight of a bisphenyldithiol complex represented by the structural formula (6), 240 parts by weight of 1,2-dichloroethane and 240 parts by weight of ethylcellosolve Was dissolved. After the obtained solution was filtered with a 0.5 μm filter, the solution was applied by spin coating to a polycarbonate substrate having a preformatted pattern formed on one side in an uneven shape to form a dye layer (recording layer) having a thickness of 100 nm. Gold is laminated on the dye layer by sputtering, and the film thickness is 80n.
A m reflective layer was formed. A protective layer having a thickness of 3 μm was formed on the reflective layer using an ultraviolet curable resin, and a write-once optical disk was obtained (optical disk A).

[0030]

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[0031]

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[0032]

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Example 2 14 parts by weight of the cyanine dye of the formula (4) used in Example 1, 3 parts by weight of the nitrosodiphenylamine derivative of the formula (5) and 3 parts by weight of a bisphenyldithiol complex of the formula (6) A write-once optical disc was produced in the same manner as in Example 1 except that the above-mentioned parts were dissolved in a mixed solvent of 240 parts by weight of 1,2-dichloroethane and 240 parts by weight of ethyl cellosolve (optical disc B).

Example 3 16 parts by weight of the cyanine dye of the structural formula (4) used in Example 1, 2 parts by weight of the nitrosodiphenylamine derivative of the structural formula (5) and 2 parts by weight of the bisphenyldithiol complex of the structural formula (6) A write-once optical disc was produced in the same manner as in Example 1 except that the above-mentioned parts were dissolved in a mixed solvent of 240 parts by weight of 1,2-dichloroethane and 240 parts by weight of ethyl cellosolve (optical disc C).

COMPARATIVE EXAMPLE 1 Except that 20 parts by weight of the cyanine dye represented by the structural formula (4) used in Example 1 was dissolved in a mixed solvent of 240 parts by weight of 1,2-dichloroethane and 240 parts by weight of ethyl cellosolve.
A write-once optical disk was manufactured in the same manner as in Example 1 (optical disk D).

Comparative Example 2 16 parts by weight of the cyanine dye of structural formula (4) used in Example 1 and 4 parts by weight of the nitrosodiphenylamine derivative of structural formula (5) were combined with 240 parts by weight of 1,2-dichloroethane and ethyl cell. A write-once optical disc was produced in the same manner as in Example 1 except that the solvent was dissolved in 240 parts by weight of Solvent (optical disc E).

Comparative Example 3 16 parts by weight of the cyanine dye of the structural formula (4) used in Example 1 and 4 parts by weight of the bisphenyldithiol complex of the structural formula (6) were combined with 240 parts by weight of 1,2-dichloroethane and ethyl Except that it was dissolved in 240 parts by weight of Cellsolve,
A write-once optical disk was manufactured in the same manner as in Example 1 (optical disk G).

The additives (nitrosodiphenylamine derivative and / or bisphenyldithiol complex) used for manufacturing the recording layers (dye layers) of the write-once optical disks A to G obtained as described above and the contents of the recording layers Table 1 summarizes the weight percentages of the additives. In Table 1, NDA indicates a nitrosodiphenylamine derivative, and BPD indicates a bisphenyldithiol complex.

Next, these optical discs A to G were left for 100 hours in an environment of a temperature of 65 ° C., a relative humidity of 80% and an illuminance of 50,000 Lx (xenon lamp). After exposure for 100 hours, the protective film and the reflective layer of the disks were peeled off, and the disks were irradiated with white light to measure the absorbance of each disk at a wavelength of 680 nm. Table 2 shows the rate of change in absorbance (change rate) before and after exposure of each disk for 500 hours.

[Table 1] Disc No. Additive Additive Content Example 1 A NDA + BPD 40% Example 2 B NDA + BPD 30% Example 3 C NDA + BPD 20% Comparative Example 1 D None 0% Comparative Example 2 E NDA 20% Comparative Example 3 F BPD 20%

[Table 2] Disk No. Additive content absorbance change rate (%) Example 1 A 40% 8.2 Example 2 B 30% 10.4 Example 3 C 20% 25.0 Comparative Example 1 D 0% 95.0 Comparative Example 2 E 20 % 51.7 Comparative Example 3 F 20% 72.6

As is clear from Table 2, the optical discs of Examples 1 to 3 have a smaller rate of change in absorbance than Comparative Examples 1 and 2, and can withstand long-time light irradiation.
In particular, it can be seen that the optical disc C of Example 3 has significantly improved light resistance of the recording layer as compared with Comparative Examples 2 and 3, as compared with the case where the nitrosodiphenylamine derivative and the bisphenyldithiol complex were used alone.

[0043]

According to the optical recording medium of the present invention, a combination of a nitrosodiphenylamine derivative and a bisphenyldithiol complex is used as an additive for a recording layer having an organic dye. It is an optical recording medium that can be improved and therefore has excellent storage stability and durability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical recording medium according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical recording medium according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 Substrate 2 Dye layer 3 Reflective layer 4 Protective layer 5 Guide groove 6 Pit 7 Center hole 8 Track 10 Optical recording medium

Claims (3)

[Claims] 1. An optical recording medium having a recording layer containing an organic dye on a substrate and recording / reproducing information by light irradiation, wherein the recording layer contains a nitrosodiphenylamine derivative and a bisphenyldithiol complex. The optical recording medium described above. 2. The optical recording medium according to claim 1, wherein the nitrosodiphenylamine derivative is represented by the following general formula (1), and the bisphenyldithiol complex is represented by the following general formula (2). . Embedded image (In the formula, R ² represents an alkyl group, an annealing group, a dialkylamino group, a hydrogen atom or a halogen atom.) (Wherein, R ¹ may be the same or different,
An alkyl group, an annealing group, a dialkylamino group, a hydrogen atom or a halogen atom, and M represents a transition metal) 3. The optical recording medium according to claim 1, wherein the organic dye is a cyanine dye.