JPH1128865A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium excellent in the lightfastness and the recording/reproducing characteristics for the light having wavelength of 680 nm or less and exhibiting a sufficient solubility to a coating solvent which does not corrode a polycarbonate substrate. SOLUTION: The optical recording medium having a recording and/or reproducing wavelength of 680 nm or less has a recording layer containing an azo dye shown by a formula (where Q1 represents an atomic group for forming an aromatic ring of 5 or 6 members which may have a fused ring, Q2 represents an atomic group for forming an aromatic ring which may have a fused ring, R1 represents an alkyl group, and X<-> represents a pair anion) wherein the complex refractive index at 635 nm has a real part (n) of 2.0-2.8 and an imaginary part (k) of 0.4 or less.

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 reflection layer and forming pits by irradiating a laser. In particular, it relates to an optical recording medium having a recording / reproducing wavelength of 600 to 680 nm.

[0002]

2. Description of the Related Art The inventors of the present invention have proposed a C (Compact Disc) standard as a recordable optical recording medium conforming to the CD (Compact Disk) standard.
D-R (write-once compact disc) has been developed.
As a dye used for the CD-R, a cyanine dye has been widely used due to its solubility, wavelength characteristics and the like. However, cyanine dyes have the disadvantage of poor lightfastness. To solve this, quencher addition, Ni, Cu
Salt formation with a dithiolene metal complex has been attempted. These methods have problems such as poor light resistance and poor solubility, resulting in poor productivity.

The cationic azo dye is disclosed in JP-A-8-244352, in which the real part (N) of the refractive index at 780 nm is at least 1.
8, and the imaginary part (k) is 0.01 to 0.15. When such a dye is used, 680 to 60
In recording / reproducing at 0 nm, the reflectance is too small to be used.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium having excellent light resistance, sufficient solubility in a coating solvent which does not attack a polycarbonate substrate, and excellent recording / reproducing characteristics at a wavelength of 680 nm or shorter. Is to provide a medium.
In particular, it is an object of the present invention to provide an optical recording medium in which a recording layer can be formed using a dye having sufficient solubility in a fluorinated alcohol-based solvent or a cellosolve-based solvent capable of improving the tact time.

[0005]

This and other objects are achieved by the following (1) and (2). (1) In an optical recording medium having a recording and / or reproducing wavelength of 680 nm or less, the following formula (I) is used.
The real part n of the complex refractive index at 5 nm is 2.0 to 2.8, and the imaginary part k
An optical recording medium comprising a recording layer containing an azo dye having a value of 0.4 or less.

[0006]

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[In the formula (1), Q ₁ represents an atomic group for forming a 5- or 6-membered nitrogen-containing aromatic ring, and may have a condensed ring. Q ₂ represents an atom group for forming an aromatic ring, and may have a condensed ring. R ₁ represents an alkyl group. X ^- represents a counter anion. Optical recording medium of the counter anion represented by is an anion of an organic metal complex (1) ^- (2) (I) in the X.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The optical recording medium of the present invention has a recording layer having a recording and / or reproducing wavelength of 680 nm or less and containing a cationic azo dye represented by the formula (I).

The real part (n) of the complex refractive index at a wavelength of 635 nm of such an azo dye is 2.0 to 2.8,
The imaginary part (k) is 0.4 or less. Such n and k
By using such a material, a sufficient reflectance and a sufficient degree of modulation of a signal can be obtained, and recording and / or reproduction with light having a wavelength of 680 nm or less, particularly 600 to 680 nm can be favorably performed. On the other hand, when n is less than 2.0, the degree of modulation of the signal becomes small, and when k exceeds 0.4, a sufficient reflectance cannot be obtained. Further, it is practically impossible to synthesize a dye in which n exceeds 2.8.

The dyes n and k are determined by forming a dye film on a predetermined transparent substrate to a thickness of about the recording layer of an optical recording medium, for example, about 40 to 100 nm under the same conditions as the recording layer. To prepare a measurement sample, and then measure the reflectance and transmittance at 635 nm of the measurement sample,
From these measured values, for example, it is calculated according to Kyoritsu Zensho "Optics" Kozo Ishiguro, pages 168 to 178. The reflectance is the reflectance of the measurement sample through the substrate or the reflectance from the dye film side, and is measured by specular reflection (about 5 °).

The azo dye represented by the formula (I) used in the recording layer of the optical recording medium of the present invention will be described. Describing the formula (I), Q ₁ represents an atomic group for forming a 5- or 6-membered nitrogen-containing aromatic ring, and may further have a condensed ring. Q ₂ represents an atom group for forming an aromatic ring, and may further have a condensed ring. R ₁ represents an alkyl group, and X ⁻ represents a counter anion.

The nitrogen-containing aromatic ring completed in Q ₁ includes:
It may be a single ring, a condensed polycyclic ring or a polycyclic ring. Examples of such an aromatic ring include a pyridine ring, a thiazole ring, a benzothiazole ring, an oxazole ring, a benzoxazole ring, a quinoline ring, an imidazole ring, a pyrazine ring, and a pyrrole ring. Among them, a thiazole ring, an imidazole ring, a pyridine ring, a quinoline ring and the like are preferable.

The alkyl group represented by R ₁ preferably has 1 to 6 carbon atoms, and may be linear or branched, but may be a straight-chain alkyl group having 1 to 4 carbon atoms. Alkyl groups are particularly preferred. Further, the alkyl group may have a substituent such as an alkoxy group (methoxy, ethoxy, etc.).

The nitrogen-containing aromatic ring completed by Q ₁ is R ₁
May further have a substituent. Examples of such a substituent include an alkyl group, an alkoxy group, a halogen atom, and a nitro group.

The aromatic ring completed by Q ₂ includes:
It may be a carbocyclic or heterocyclic ring, a monocyclic ring, a condensed polycyclic ring or a polycyclic ring assembly. Examples of such an aromatic ring include a benzene ring, a naphthalene ring, an indole ring, a pyridine ring, a thiazole ring, a benzothiazole ring, an oxazole ring, a benzoxazole ring, a quinoline ring, an imidazole ring, a pyrazine ring, and a pyrrole ring. Among them, a benzene ring, a pyrrole ring, an indole ring and the like are preferable.

The aromatic ring completed in Q ₂ may further have a substituent. Examples of such a substituent include an alkyl group, an aryl group, an amino group (particularly, a dialkylamino group), an alkoxy group, and a halogen atom. Atom, nitro group and the like. Among these, when the aromatic ring completed by Q ₂ is a benzene ring, it preferably has a dialkylamino group at the p-position of the bonding position of -N = N- in the benzene ring.

[0017] X ^- include anions represented by, specifically a halide ion ^{(Cl -, Br -, I} - , etc.), C
_{^{lO 4 -, BF 4 -,}} PF 6 -, VO 3 -, VO 4 3-, WO
_{^{4 2-, CH 3 SO 3 -}} , CF 3 COO -, CH 3 COO
_{^{-, HSO 4 -, CF 3}} SO 3 -, PO 4 · 12WO 3 3-,
Examples thereof include p-toluenesulfonic acid ion (PTS ⁻ ) and p-trimethyl phenylsulfonic acid ion (PFS ⁻ ). Among them, ClO ₄ ⁻ , BF ₄ ^{− and the} like are preferable.

Further, an anion of an organometallic complex is mentioned as a preferable example. Such organometallic complexes include those known as metal complex quenchers. Specific examples include an anion of a metal complex such as an acetylacetonate type, a bisdithiol type such as a bisdithio-α-diketone type or a bisphenylenedithiol type, a thiocatechol type, a salicylaldehyde oxime type, or a thiobisphenolate type. Can be Among them, an anion of a bisphenylenedithiol-based metal complex is preferable. The anion of the bisphenylenedithiol-based metal complex is preferably an anion represented by the following formula (A-1).

[0019]

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In the formula (A-1), M represents a central metal, and Ni, Cu, Co, Pd, Pt
And the like, and Ni, Cu and the like are preferable. R represents an alkyl group, an alkoxy group, an alkyl-substituted amino group or a halogen atom. n is an integer of 1 to 4.

The alkyl group represented by R may be linear or branched, and preferably has 1 to 4 carbon atoms, and is preferably methyl, ethyl, n-propyl, isopropyl or n-alkyl. Butyl, isobutyl, sec-butyl, t-
Butyl and the like. The alkoxy group has 1 carbon atom
To methoxy, ethoxy and the like. As the alkyl-substituted amino group, those substituted with an alkyl group having 1 to 4 carbon atoms are preferable, di-substituted products are preferable, and dibutylamino and the like can be mentioned. Examples of the halogen atom include Cl and the like.

N is an integer of 1 to 4, and is particularly preferably an integer of 1 to 3.

Specific examples of the anion represented by the formula (A-1) are shown below, but the present invention is not limited thereto. Here, according to the expression such as the formula (A-1a), M, R
It is indicated by a combination such as ⁰¹ .

[0024]

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Further, there may be mentioned an anion of a phenylazophenyl metal complex, and those represented by the following formula (A-2) are preferred.

[0026]

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In the formula (A-2), R ^{1 to} R ⁴ each represent a nitro group, a halogen atom, an amino group, a sulfamoyl group, an alkyl group or an alkoxy group, and t to w are each an integer of 0 to 4. . M ¹ represents cobalt or nickel. However, t, u, v and w do not become 0 at the same time, and t + u + v + w is 1-16.

The formula (A-2) will be further described.
The halogen atoms represented by R ^{1 to} R ⁴ include F, C
l, Br, I and the like.

The amino groups represented by R ^{1 to} R ⁴ include
It may have a substituent such as an alkyl group, an alkoxy group, or an acyl group, and these substituents may be further substituted with a halogen atom (Cl, Br, I, or the like), a hydroxy group, an alkoxy group, or the like. . As the amino group represented by R ^{1 to} R ⁴ , specifically, an amino group, a methylamino group,
Examples include a dimethylamino group, an acetylamino group, and a benzylamino group. The total carbon number of such an amino group is preferably from 0 to 8.

The sulfamoyl group represented by R ^{1 to} R ⁴ may have a substituent such as an alkyl group or an alkoxy group, and these substituents may be further substituted with a halogen atom (Cl, Br, I, etc.). ) Or a hydroxy group or an alkoxy group. As the sulfamoyl group represented by R ^{1 to} R ⁴ , specifically, a sulfamoyl group,
N-methylsulfamoyl group, N, N-dimethylsulfamoyl group, N, N-diethylsulfamoyl group,
N-methylhydroxyethylsulfamoyl group, N, N
-Methoxyethylsulfamoyl group, N-methoxyethylsulfamoyl group and the like. The total carbon number of such a sulfamoyl group is preferably 0 to 10.

The alkyl group represented by R ^{1 to} R ⁴ is preferably an alkyl group having 1 to 4 carbon atoms, which may be linear or branched and having a substituent (for example, a halogen atom , An alkoxy group, etc.), specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group,
Examples include a t-butyl group and a methoxyethyl group.

As the alkoxy group represented by R ^{1 to} R ⁴ , those having 1 to 4 carbon atoms in the alkyl portion are preferable.
It may have a substituent (for example, a halogen atom or the like),
Specific examples include a methoxy group and an ethoxy group.

Each of t to w is an integer of 0 to 4 and these are not simultaneously 0, and t + u + v + w is 1 to 1
6. When t, u, v, and w are integers equal to or greater than 2, each R ¹ , each R ² , each R ³ , and each R ⁴ may be the same or different, and are adjacent to each other. The compounds may be combined with each other to form a condensed ring (such as a benzene ring). t, u, v, w are preferably 0, 1, 2 under the above conditions, and particularly preferably 1.

In the equation (A-2), t = u = v = w
= 1, R ¹ = R ³ , and R ² = R ⁴ .

In the formula (A-2), M ¹ is Co or Ni, particularly preferably Co.

Specific examples of the anion represented by the formula (A-2) are shown below, but the present invention is not limited thereto. Here, R ^{11 in the} formulas (A-2a) and (A-2b)
When R ^{11 to} R ^{14 and the} like are all H, they are H, and when R ^{11 to} R ¹⁴ are substituents, they are only shown and H is omitted.

[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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As the anion, an anion of an organometallic complex is particularly preferred.

Hereinafter, the general formula (I) used in the present invention will be described.
However, the present invention is not limited to these. Here, it is shown according to the display of formulas (I-1) to (I-5), and when X ⁻ is an organometallic complex anion, it is shown according to the display exemplified above.

[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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The azo dye of the general formula (I) is, for example, of the formula (I-
The compound of 1) can be synthesized according to the following scheme A.

[0050]

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Also, Topics in Applied Chemistry: The
Chemistry and Application of Dyes, DRWaring and
G. Hallas, Eds., Plenum Press, New York, Chap. 5. (1990)
The synthesis can be performed by the method described in (1).

[0052] Further, in order to obtain an azo dye having an anion of organometallic complex, ClO ₄ ^- salt, BF ₄ ^- After synthesizing the salt, depending on the anion of organometallic complex of interest, the organometallic complex salt Anions may be exchanged using (for example, the following compounds B1 and B2) according to a known method.

[0053]

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[0054]

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The azo dye of the present invention has a melting point (mp) of 220.
３５０350 ° C., and λmax (measured with a 50 nm thick dye thin film) is in the range of 480 to 630 nm.

With respect to the above exemplified compounds, λ max, n,
k.

[0057]

[Table 1]

The azo dyes of the present invention may be used alone or in combination of two or more as dyes for the recording layer.

These dyes are excellent in light resistance, have sufficient solubility in organic solvents, and have high solubility in coating solvents which do not attack polycarbonate resin (PC) which is widely used as a substrate material for optical recording media. Become.

The recording layer using these dyes is particularly preferably used for a write-once optical recording disk (DVD-R). Such a recording layer can be formed using a dye-containing coating solution. In particular, it is preferable to use a spin coating method in which the coating solution is spread and applied on a rotating substrate. In addition, gravure coating, spray coating, dipping, or the like may be used.

After the spin coating as described above, the coating film is dried if necessary. The thickness of the recording layer formed in this way is appropriately set according to the target reflectance and the like, but is usually 500 to 3000 A.

The content of the dye in the coating solution is usually preferably 0.05 to 10% by weight. Since the azo dye of the present invention has good solubility, it is easy to easily prepare a coating solution having such a content. Specifically,
The azo dye of the present invention mainly shows good solubility in polar solvents, and alcohols and cellosolves or alkoxy alcohols, keto alcohols such as diacetone alcohol,
It is dissolved in a ketone such as cyclohexane or a fluorinated alcohol such as 2,2,3,3-tetrafluoropropanol in an amount of 0.5 to 10% by weight. Dissolve 1% by weight or more in ethyl cellosolve or 2,2,3,3-tetrafluoropropanol, which is a suitable coating solvent especially when applying to a polycarbonate disk, and form a good quality spin coat film in a short time. Is possible.

The coating liquid may contain a binder, a dispersant, a stabilizer and the like as appropriate.

The recording layer of the optical recording medium of the present invention may contain another type of light absorbing dye in addition to the dye of the present invention. Examples of such a dye include a cyanine dye, a metal complex dye different from the above, a styryl dye, a porphyrin dye, an azo dye different from the above, and a formazan metal complex. In such a case, the recording layer may be formed by including such a dye in the coating solution.

Examples of the coating solvent used in the present invention include alcohols (including alkoxy alcohols such as keto alcohols and ethylene glycol monoalkyl ethers), aliphatic hydrocarbons, ketones, and esters. System, ether system, aromatic system, alkyl halide system and the like.

Of these, alcohols and aliphatic hydrocarbons are preferred. Among alcohols, alkoxy alcohols and keto alcohols are preferred.
In the alkoxy alcohol system, the alkoxy moiety preferably has 1 to 4 carbon atoms, and the alcohol moiety has 1 to 5 carbon atoms, more preferably 2 to 5 carbon atoms, and the total carbon atom is 3 To 7 is preferable.
Specifically, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (also referred to as ethyl cellosolve, ethoxyethanol), butyl cellosolve, 2-isopropoxy-1-
Ethylene glycol monoalkyl ether (cellosolve) such as ethanol, 1-methoxy-2-propanol, 1-methoxy-2-butanol, 3-methoxy-1
-Butanol, 4-methoxy-1-butanol, 1-ethoxy-2-propanol and the like. Examples of keto alcohols include diacetone alcohol.
Furthermore, a fluorinated alcohol such as 2,2,3,3-tetrafluoropropanol can also be used.

Examples of the aliphatic hydrocarbons include n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, dimethylcyclohexane, n-octane, iso-propylcyclohexane,
T-butylcyclohexane and the like are preferable, and among them, ethylcyclohexane and dimethylcyclohexane are preferable.

The ketones include, for example, cyclohexanone.

In the present invention, alkoxy alcohols such as ethylene glycol monoalkyl ether are particularly preferable. Among them, ethylene glycol monoethyl ether, 1-methoxy-2-propanol and 1-methoxy-
2-butanol and the like are preferable, and a mixed solvent thereof may be used. Examples thereof include a combination of ethylene glycol monoethyl ether and 1-methoxy-2-butanol. Further, fluorine alcohol is also preferably used.

FIG. 1 shows an example of the configuration of a write-once digital video disc (DVD-R) for recording / reproducing at short wavelengths of about 635 nm and 650 nm, which is a preferred embodiment of the optical recording medium of the present invention. FIG. 1 is a partial sectional view.

As shown in FIG. 1, the optical recording disk 10
Is an optical recording disk conforming to the DVD standard, which is formed by bonding two protective films 15 and 25 of the same structure to each other. The thickness of the adhesive layer 50 is 1
It is about 0 to 200 μm. In this case, the thickness of one substrate (usually, polycarbonate resin) is 0.6 mm, and the recording layer 13 is formed on the substrate 12 having the groove 123.
The reflection layer 14 and the protection film 15 are sequentially formed,
Recording layer 23 and reflection layer 2 on a substrate 22 having
4. A protective film 25 is formed and obtained by bonding as described above. As a bonding method, a hot melt adhesive, a slow-acting UV adhesive, a pressure-sensitive adhesive sheet, or the like can be used.

The substrate 12 or 22 is disk-shaped, and includes recording light and reproduction light (wavelengths of 600 to 680) to enable recording and reproduction from the back side of the substrate 2.
nm, furthermore, a wavelength of about 630 to 680 nm, especially about 635 to 680 nm laser light, especially 635 nm
Or 650 nm) is preferably formed using a resin or glass which is substantially transparent (preferably at a transmittance of 88% or more). The size is about 64 to 200 mm in diameter and about 0.6 mm in thickness.

The recording layer 13 or 2 of the substrate 12 or 22
As shown in FIG. 1, tracking grooves 123 or 223 are formed on the surface on which the third member 3 is formed. Groove 12
Preferably, 3 or 223 is a spiral continuous groove having a depth of 0.05 to 0.20 μm (5
00 to 2000 A), the width is preferably 0.20 to 0.40 μm, and the groove pitch is preferably 0.65 to 0.85 μm. By making the groove like this,
A good tracking signal can be obtained without lowering the reflection level of the groove. In particular, the groove width is set to 0.
It is important to regulate the thickness to 20 to 0.40 μm. If the groove width is less than 0.2 μm, it is difficult to obtain a sufficiently large tracking signal, and a slight offset of tracking during recording causes an increase in jitter. Cheap. Also, as the groove width increases, waveform distortion tends to occur.

The material of the substrate 12 or 22 is preferably a resin, and various thermoplastic resins such as polycarbonate resin, acrylic resin, amorphous polyolefin, TPX, and polystyrene resin are suitable. And it can manufacture according to well-known methods, such as injection molding, using such a resin. The groove 123 or 223 is preferably formed when the substrate 12 or 22 is formed. After manufacturing the substrate 12 or 22, 2P
A resin layer having grooves 123 or 223 may be formed by a method or the like. In some cases, a glass substrate may be used.

As shown in FIG. 1, the substrate 12 or 2
The recording layer 13 or 23 provided in No. 2 is preferably formed by the spin coating method as described above using the above-mentioned dye-containing coating solution. Spin coating is performed under normal conditions, with a rotation speed of 500 from the inner circumference to the outer circumference.
It may be performed by adjusting the speed between 5000 rpm and the like.

The recording layer 13 or 23 thus formed has a thickness of 50 to 300 nm (500 to 3000).
A), and the complex refractive index at the recording light and reproduction light wavelengths is real part n = 2.0 to 2.8 and imaginary part k = 0.4 or less.

If the thickness is outside the above range, the reflectivity decreases, and it becomes difficult to perform good reproduction.

Further, by controlling n and k as described above, good recording and reproduction can be performed. If k exceeds 0.4, a sufficient reflectance cannot be obtained. If n is less than 2.0, the degree of modulation of the signal is too small. Although the upper limit of n is not particularly limited, it is usually about 2.8 for convenience in the synthesis of the dye compound.

The recording layers n and k can be determined by preparing a recording sample on a predetermined transparent substrate to a thickness of, for example, about 40 to 100 nm under actual conditions, and preparing a measurement sample. The reflectance is determined by measuring the reflectance of the measurement sample through the substrate or the reflectance from the recording layer side. In this case, the reflectance is measured by specular reflection (about 5 °) using the recording / reproducing light wavelength (635 nm or 650 nm). Also, the transmittance of the sample is measured. Then, from these measured values, n and k may be calculated in accordance with, for example, Kyoritsu Zensho “Optics” Kozo Ishiguro P168-178.

As shown in FIG. 1, a reflective layer 14 or 24 is provided on the recording layer 13 or 23 in close contact with the recording layer. As the reflection layer 14 or 24, Au, Cu,
It is preferable to use a metal or alloy having a high reflectance such as Al, Ag, AgCu, or the like. The thickness of the reflection layer 14 or 24 is 50 nm
(500 A) It is preferable that the thickness be equal to or more than that, and the layer be formed by vapor deposition, sputtering or the like. The upper limit of the thickness is not particularly limited.
It is preferably about 20 nm (1200 A) or less.
Thereby, the reflectance of the reflective layer 14 or 24 alone is:
The reflectance is 90% or more, and the reflectance of the unrecorded portion of the medium through the substrate is sufficient.

As shown in FIG. 1, a protective film 15 or 25 is provided on the reflective layer 14 or 24. The protective film 15 or 25 may be formed of various resin materials such as an ultraviolet curable resin, for example, and usually has a thickness of about 0.5 to 100 μm. The protective film 15 or 25 may be in the form of a layer or a sheet. Protective film 15 or 25
May be formed by an ordinary method such as spin coating, gravure coating, spray coating, dipping, or the like.

For recording or additional recording on the optical recording disk 1 having such a configuration, for example, 635 nm or 650 nm
The recording light of nm is irradiated in a pulse shape through the substrate 12 or 22 to change the light reflectance of the irradiated portion. When the recording light is irradiated, the recording layer 13 or 23 absorbs the light and generates heat, and at the same time, the substrate 12 or 22 is also heated. As a result, in the vicinity of the interface between the substrate 12 or 22 and the recording layer 13 or 23, the material of the recording layer such as a dye is melted or decomposed, and the interface between the recording layer 13 and the substrate 12 or the interface between the recording layer 23 and the substrate 22 is formed. Pressure may be applied and deform the bottom and side walls of the groove.

[0083]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention together with comparative examples.

Example 1 Dye I-1-1 was used as a dye for an optical recording layer, and had a pregroove (depth 0.12 μm, width 0.30 μm, groove pitch 0.74 μm), a diameter of 120 mm and a thickness of 0. A recording layer containing a dye was formed on a 0.6 mm polycarbonate resin substrate by spin coating at 1000 A (10 A).
0 nm). As a coating solution in this case,
A 1.0 wt% 2,2,3,3-tetrafluoropropanol solution was used. Next, an Au reflective layer was added to this recording layer.
A transparent protective film (thickness: 5 μm) of an ultraviolet curable acrylic resin was formed by sputtering to a thickness of 50A. Two disks formed in the same manner were adhered with an adhesive with the protective films facing inward to produce a disk (see FIG. 1).

This is designated as Sample No. 1.

In the sample No. 1, the dye for the recording layer was replaced by the dye I-2 instead of the dye I-1-1.
Samples were prepared in the same manner except that -1 and I-3-1 were used. Sample No.
Signals were recorded at a linear velocity of 3.5 m / s using a laser beam of 635 nm on the sample Nos. 1, 2, and 3 produced in this manner. 65 of 5m / s
Reproduction was performed with a 0 nm laser beam, and the characteristics were evaluated. Note that the lens aperture diameter NA was 0.60. Characteristics include reflectance at 650 nm, degree of modulation (14 TMod.), And jitter (Jitt).
er) and the optimum recording power (P0) at 635 nm.

The results are shown below.

Sample No. P0 (mW) Reflectivity (%) Modulation degree (%) Jitter (%) 1 12 50 65 8 2 11 51 60 7.8 3 12 50 63 8

From the above, it can be seen that the reflectance, the degree of modulation, and the jitter are all good.

Further, the light resistance of the samples Nos. 1, 2 and 3 was examined. A light resistance of 40,000 xenon lamp (Shimadzu xenon fade meter) with 80,000 lux.
It was examined by measuring the jitter of the disk after irradiation for a period of time. The jitter did not change for any of the samples. In addition, a reliability test was performed at 80 ° C. and 80% RH for 100 hours, and there was no deterioration in characteristics.

Example 2 As a dye for an optical recording layer, a dye I-1-1 obtained from the dye I-1-1 and the above-mentioned metal complex B1 (Na salt of the exemplified anion A-2a-1). 4 and a pre-groove (depth 0.14 μm, width 0.35 μm, groove pitch 0.7)
A recording layer containing a dye was formed to a thickness of 1000 A (100 nm) on a polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm having a thickness of 4 μm) by spin coating. As a coating liquid in this case, 1.2 wt% of 2,
A 2,3,3-tetrafluoropropanol solution was used. Next, an Au reflection layer was formed on this recording layer to a thickness of 850 A by a sputtering method, and a transparent protective film (thickness: 5 μm) of an ultraviolet curable acrylic resin was formed. Two disks formed in the same manner were adhered with an adhesive with the protective films facing inward to produce a disk (see FIG. 1).

This is designated as Sample No. 4.

In sample No. 4, the dye for the recording layer was changed to dye I-2-4 instead of dye I-1-4.
1 and the aforementioned metal complex B2 (an example of the anion A-1a-1)
Dye I obtained from
A sample was prepared in the same manner except that -2-2 was used. These samples were designated as sample No. 5. Signals were recorded at a linear velocity of 3.5 m / s using laser light of 635 nm on samples Nos. 4 and 5 produced in this manner. Reproduction was performed with a 650 nm laser beam at a speed of 3.5 m / s, and the characteristics were evaluated. Note that the lens aperture diameter NA =
0.60. Characteristics include reflectance at 650 nm, degree of modulation (14 TMod.), Jitter (Jitter), 63
The optimum recording power (P0) at 5 nm was evaluated.

The results are shown below.

Sample No. P0 (mW) Reflectivity (%) Modulation (%) Jitter (%) 4 9.5 47 65 7.5 5 9.0 45 67 8.2

From the above, it can be seen that the reflectance, the degree of modulation, and the jitter are all good.

Further, the light resistance of the samples Nos. 4 and 5 was examined. The light fastness was determined by irradiating a xenon lamp of 80,000 lux (Xenon fade meter manufactured by Shimadzu Corporation) for 40 hours and then measuring the jitter of the disk. The jitter did not change for any of the samples. In addition, a reliability test was performed at 80 ° C. and 80% RH for 100 hours, and there was no deterioration in characteristics.

In the samples of Examples 1 and 2, Dye I
-1-2, I-1-3, I-1-5 to 7, I-2-3 to
6, I-3-2-4, I-4-1-4, I-5-1-4
When the characteristics were examined in the same manner as described above, the same results as in Examples 1 and 2 were obtained depending on the anion of the azo dye.

Comparative Example 1 A disk sample was prepared in the same manner as in Example 1 except that the cyanine dye T1 (described below) was used. In the evaluation of the manufactured sample, sufficient light resistance was not obtained, and the jitter was largely deteriorated. Also in the reliability test, the degree of modulation and the deterioration of jitter were large.

[0100]

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Comparative Example 2 Azo Dye T disclosed in JP-A-8-244352 shown below
Disc samples were prepared and evaluated in the same manner as in Example 1 except that No. 2 (Dye 4 in Example 1 of the above publication) was used. N, k at 635 nm of this dye T2
Were 1.8 and 0.53. Regarding the disk characteristics, the reflectance was 10% or less, the degree of modulation was 30%, and the jitter was poor.

[0102]

Embedded image

[0103]

According to the present invention, by using a cationic azo dye excellent in solubility, light resistance and reliability as the light absorbing layer, the recording sensitivity, the reflectance and the modulation degree are excellently balanced, and the recording sensitivity is improved. An optical recording medium having excellent characteristics such as high jitter and small jitter can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an example of an optical disk of the present invention.

[Explanation of symbols]

 Reference Signs List 10 optical recording disk 12, 22 substrate 123, 223 groove 13, 23 recording layer 14, 24 reflection layer 15, 25 protective layer 50 adhesive layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C07D 277/50 C07D 277/50 417/12 207 417/12 207

Claims (2)

[Claims] 1. A recording and / or reproducing wavelength of 680 nm.
The following optical recording medium contains an azo dye represented by the following formula (I) wherein the real part n of the complex refractive index at 635 nm is 2.0 to 2.8 and the imaginary part k is 0.4 or less. An optical recording medium, comprising: a recording layer. Embedded image [In the formula (1), Q ₁ represents an atomic group for forming a 5- or 6-membered nitrogen-containing aromatic ring, and may have a condensed ring. Q ₂ represents an atom group for forming an aromatic ring,
It may have a condensed ring. R ₁ represents an alkyl group.
X ^- represents a counter anion. ] 2. The optical recording medium according to claim 1, wherein the counter anion represented by X ⁻ in the formula (I) is an anion of an organometallic complex.