JPH09254543A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a write-once optical recording medium capable of being reproduced by two kinds of wavelengths. SOLUTION: A recording layer containing org. coloring matter satisfies conditions such that there is absorption max. B1 on a side of a wavelength shorter than a first recording reproducing wavelength λ1 (760-800nm) by 50-70nm (a), absorbancy within a wavelength range of λ1 ±5nm is 10% of absorbancy at B1 or less (b), there is second absorption max. B2 on a side of a wavelength shorter than a second reproducing wavelength λ2 (600-700nm) by 40-80nm (c) and absorbancy within a wavelength range of λ2 ±5nm is 10% of absorbancy at B2 or less (d).

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,
More specifically, the present invention relates to an optical recording medium on which recording can be performed by laser light.

[0002]

2. Description of the Related Art Recently, CD-ROMs and CDs have come into widespread use, and along with this, a write-once type CD, that is, a CD that can be recorded by a user.
-R demand is also growing. Furthermore, for high density recording,
Attention has been paid to shortening the oscillation wavelength of laser light.
There is a demand for an optical recording medium capable of recording and reproducing with a laser beam having a wavelength shorter than 830 nm. Under such circumstances, a type capable of reproducing with a shorter wavelength laser is desired for a CD-R medium that records and reproduces data at around 780 nm.

[0003]

In the above-mentioned prior art, the organic dye-based optical recording medium has been used as a CD-R medium because it is inexpensive and easy on the process.
Organic dyes have a disadvantage that they have a large wavelength dependence, unlike inorganic materials such as phase change and magneto-optical recording media. Conventionally used organic dyes for CD-R are mainly classified into two types. One having an absorption maximum in the vicinity of 600 nm to 700 nm and one having a small absorption band in this wavelength range. In the former type, when a portion recorded with a laser near 780 nm is reproduced with a short wavelength laser, a certain degree of modulation can be obtained, but due to the absorption, 600 nm
10% reflectance at short wavelength laser wavelength of ~ 700nm
Since it is far below the range, there are difficulties in reproduction such as tracking. In the latter type, since the absorption itself is small, a reflectance of about 20% to 30% is obtained when reproducing with the above short wavelength laser, and although there is no difficulty in reproduction, a sufficient degree of modulation is obtained because of the small refractive index. Absent. In order to solve such a problem, for example, JP-A-7-156550 and JP-A-8-31010 propose to mix two or more dyes. However, the reflectance at short wavelength is 30%
Conditions for obtaining good signal characteristics while obtaining sufficient reflectance at two wavelengths, such as parameter control below by the refractive index or extinction coefficient of the organic dye layer, which is extremely difficult to measure in reality Is not enough.

[0004]

Means for Solving the Problems The present inventors have intensively studied conditions for obtaining a sufficient reflectance at two wavelengths and obtaining good signal characteristics and a medium, and have reached the present invention. The gist of the present invention is an optical recording medium in which at least a recording layer containing an organic dye, a metal reflection layer, and a protective layer are laminated on a transparent substrate in this order, with the recording layer being a film on the transparent substrate. An optical recording medium characterized by satisfying the conditions (a) to (d).

(A) First recording / reproducing wavelength λ ₁ (760n
m to 800 nm), and has an absorption maximum B ₁ on the shorter wavelength side of 50 nm to 70 nm. (B) The absorbance at λ ₁ ± 5 nm is 10 times that at B _1.
% Or less. (C) Second reproduction wavelength λ ₂ (600 nm to 700 nm)
Second absorption maximum B on the shorter wavelength side of 40 nm to 80 nm than
Having _two . (D) The absorbance at wavelength λ ₂ ± 5 nm is 1 of the absorbance at B _2.
0% or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The recording layer in the present invention is reduced in temperature by increasing the temperature by absorbing the laser beam for recording, the film thickness is reduced, and the optical characteristics are changed, the phase of the return light is changed, and the reflectance is changed. However, the recording unit is used.

In the present invention, as the transparent substrate, a known one such as resin such as polycarbonate, polymethacrylate, amorphous polyolefin or glass is used, and it has a guide groove for servo. The groove has a depth of typically 10
0-200 nm, preferably 140-180 nm,
The groove width is usually 0.45 to 0.5 μm, and the track pitch is
Usually, it is 1 to 1.6 μm, and the groove shape is preferably a U-shaped groove. When the depth of the groove is less than 100 nm, a sufficient change does not occur during recording, and a sufficient recording modulation degree may not be obtained. If the thickness exceeds 200 nm, the reflectance difference between the groove and the groove is too large, and in the case of recording on the groove, the reflectance is too low, which is not good. If the groove width is less than 0.45 μm, it may be difficult to obtain a sufficient tracking error signal amplitude. On the other hand, if the groove width exceeds 0.5 μm, the recording portion tends to spread laterally during recording, which is not preferable. Track pitch is from 1.0 μm
1.6 μm is preferable. It should be noted that the optical measurement is performed using a He-Ne laser, or the profile is measured using STM or AFM. This case was determined by STM.

The recording layer is usually obtained by spin-coating a solution in which an organic dye or the like is dissolved in a solvent such as ethanol, 3-hydroxy-3-methyl-2-butanone, diacetone alcohol, or fluorine-based alcohol. As this solvent, a solvent having a boiling point of 100 to 150 ° C. and n of 3 or more, such as 1H, 1H, 3H-tetrafluoropropanol, 1H, 1H, 5H-octafluoropentanol, 1H. 1H, 3H-hexafluorobutanol and the like are preferably used. Boiling point is 10
If the temperature is lower than 0 ° C, the solvent evaporates quickly during spin coating, so that the coating liquid does not spread to the outer peripheral side of the disc radius of 40 mm, and the radial film thickness distribution becomes extremely large, and good characteristics can be obtained. It is not preferable because it may not exist. On the other hand, when the temperature exceeds 150 ° C., it takes time to evaporate and the solvent is likely to remain in the film, and in such a case, good recording jitter is often not obtained. The thickness of the film is preferably about 60 to 180 nm in the groove. If it is less than 60 nm, it may be too thin to obtain good recording sensitivity. On the other hand, when the thickness exceeds 180 nm, deformation of the recording portion in the horizontal direction and the scanning direction becomes large, so that crosstalk and jitter increase, which is not preferable. By the way, since the spin coating method is used to apply the organic dye, the ratio of the film thickness of the groove portion to the land portion is: groove depth, dye concentration, dye solution viscosity, substrate material / solvent wettability, film formation. It depends on a number of parameters such as rotation speed and wind speed. Therefore, if only the average film thickness of the land portion and the groove portion is used as a parameter as in JP-A-8-31010, it is difficult to obtain information on the actual film thickness of the groove portion that is related to the signal characteristics themselves. In particular, when the substrate is a polymer material such as polycarbonate, it is technically extremely difficult to cut out the cross section of the substrate, so that it is difficult to measure the actual film thickness of the recording layer in the groove portion and the land portion. What can be actually measured is the groove depth between the land portion and the coating film, and the film thickness of the groove portion can be calculated from these two values. In the present case, the groove depth of the coating film is 50 to 180 nm, and it is preferably U-shaped. If the groove depth is less than 50 nm, a sufficient tracking error signal amplitude cannot be obtained, and
If it exceeds 180 nm, the film thickness of the groove is too thin, and there is a possibility that sufficient recording modulation cannot be obtained.

In the present invention, when the film is formed on the substrate, the recording layer needs to satisfy the following conditions (a) to (d).
(A) Absorption maximum B ₁ on the shorter wavelength side of 50 to 70 nm than the recording / reproducing wavelength λ ₁ (760 to 800 nm),
(B) Absorbance at λ ₁ ± 5 nm is 10% of that at B _1.
The second reproduction wavelength λ ₂ (600-
The absorption maximum B ₂ should be 40 to 80 nm shorter than 700 nm), and (d) the absorbance at λ ₂ ± 5 nm should be 10% or less of the absorbance at B ₂ . The ratio of the absorbance at B ₁ to the absorbance at B ₂ is usually B ₁ : B ₂ = 1:
It is 9 to 9: 1, preferably 3: 7 to 9: 1, more preferably 3: 7 to 7: 3, and particularly preferably 5: 5 to 7: 3. A single dye may be used as long as it is an organic dye for optical recording satisfying such conditions, but usually two or more dyes are mixed and used as a recording layer.

Organic dyes used for optical recording include
Phthalocyanine dyes, cyanine dyes, metal-containing azo dyes, and dibenzofuranone-based and metal-containing indoaniline dyes have been proposed. Among them, in order to obtain high reflectance at 2 wavelengths, a wavelength of 760 nm to 800 nm is required. The recording / reproducing dye at λ ₁ (dye 1) and the reproducing organic dye at a wavelength of 600 nm to 700 nm λ ₂ (dye 2) have required characteristics. Dye 1 should not only provide the CD-R Orange Book satisfying properties, but also should be a dye that has a smaller half-width of absorption than conventional dyes for CD-R.

Specifically, in the state of a film of Dye 1 on a transparent substrate, it has an absorption maximum B ₁ on the shorter wavelength side than λ ₁ by 50 nm to 70 nm, and the absorbance at λ ₂ is the absorbance at B _1. It is preferably less than 5%. The requirement that the absorbance at λ ₂ is less than 5% is a different requirement from the conventional dye for CD-R. Whether the conventional dye is a cyanine dye or a phthalocyanine dye, the full width at half maximum of the absorption band is large because of its large association. In the present case, it is preferable to select the following phthalocyanine dye as the dye 1 from the viewpoint of easily providing a substituent that suppresses the association property, and specifically, the phthalocyanine-based dye represented by the following general formula [1] is mentioned. To be

[0012]

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(In the formula, A1 to A4 represent an alkyl group which may have a substituent, a phenyl group, a cyclohexyl group, an alkoxy group, a phenoxy group and a cyclohexyloxy group, and Z1 to Z4 represent a halogen atom and a nitro group. Represents a group.
n1-n4 represent the integer of 0-3. M represents a divalent metal atom, a trivalent or tetravalent substituted metal atom, a metal oxide or two hydrogen atoms. )

Among them, the halogen atom represented by Z1 to Z4 includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a bromine atom is particularly preferable. n1-n
4 is particularly preferably 0 or 1.

As an example of the divalent metal atom represented by M,
Is Cu, Ni, Co, Zn, Fe, Mn, Mg, P
d, Ru, Pt, Rh, Ca, Ba, Cd, Hg, P
b, Sn, Ti, Be, Cr and the like can be mentioned. 1 substitution 3
Examples of the valent metal atom include AlF, AlCl, AlB
r, AlI, GaF, GaCl, GaBr, GaI, I
nF, InCl, InBr, InI, TlF, TlC
1, TlBr, TlI and the like. 2-substituted tetravalent metal
For example, SiF_Two, SiCl_Two, SiBr_Two, SiI_Two,
GeF_Two, GeCl_Two, GeBr_Two, GeI_Two, SnF_Two, SnC
l_Two, SnBr_Two, SnI_Two, TiF_Two, TiCl_Two, TiBr_Two,
TiI_Two, ZrCl_Two, HfCl_Two, Si (OH)_Two, Ge (O
H)_Two, Sn (OH)_Two, Zr (OH)_Two, Hf (OH)_Two, S
iR_Two, GeR_Two, SnR_Two, TiR_Two(Where R has a substituent
It represents an optionally substituted alkyl group or aryl group. ),
Si (OR ')_Two, Ge (OR ')_Two, Sn (OR ')_Two, T
i (OR ') _Two(Wherein R'may have a substituent
Alkyl group, aryl group, acyl group, trialkylsilyl
Represents a luoxy group, a PO group, a CO group, and the like. ) Etc.
It is. Examples of metal oxides include VO, TiO, PbO, etc.
No. Examples of particularly preferred metal atoms include Pd,
Cu, Ni, Pb, SnCl_Two, Si (OR ')_Two, RA
1, VO and TiO.

Phthalocyanine dyes particularly suitable for the present invention are represented by formulas (3), (4), (5), (6) and (7) shown in Tables 1, 2, 3, 4 and 5, respectively.
The compound represented by these is mentioned.

[0017]

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[0018]

[Table 1]

[0019]

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[0020]

[Table 2]

[0021]

[Chemical 6]

[0022]

[Table 3]

[0023]

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[0024]

[Table 4]

[0025]

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[0026]

[Table 5]

On the other hand, the dye 2 also has an absorption maximum B ₂ at 40 nm to 80 nm longer than the wavelength λ ₂ in the same state as a film on a transparent substrate, and the absorbance at λ ₂ is 10 of the absorbance at B _2. % Or less. Organic dyes that satisfy such conditions include cyanine dyes, metal-containing azo dyes, dioxazine dyes,
There are various things such as quinone dyes, but especially storage stability,
A metal-containing azo dye is preferable from the viewpoint of excellent light resistance, and specific examples thereof include a metal-containing azo dye represented by the following general formula (2).

[0028]

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(In the formula, R ₅ and R ₆ are each independently
R ₅ represents a hydrogen atom, an optionally substituted alkyl group, an aryl group, an alkenyl group or a cycloalkyl group, and R ₅
And R ₆ may be cyclized to form a hydrocarbon ring or a heterocycle. The nitrogen-containing heterocycle A and the benzene ring B may have a substituent. X is a hydroxy group, a carboxylic acid group,
It represents a sulfonic acid group or a salt thereof. ) These dyes have particularly good absorption characteristics and refractive index at 600 to 700 nm.

In the general formula [2], R ₅ and R ₆ are
More specifically, each independently a hydrogen atom; methyl group, ethyl group, n-propyl group, isopropyl group, n-
Butyl group, tert-butyl group, sec-butyl group, n
-Pentyl group, n-hexyl group, n-heptyl group, n-
C1-C20 alkyl groups such as octyl group, n-decyl group, n-dodecyl group, and n-octadecyl group, preferably C1-C10 alkyl groups, more preferably C1-C6 alkyl groups. An aryl group having 6 to 12 carbon atoms such as a phenyl group, a tolyl group, a xylyl group and a naphthyl group; a vinyl group, a 1-propenyl group, an allyl group, an isopropenyl group, a 2-butenyl group, a 1,3-butadienyl group, It represents an alkenyl group having 2 to 10 carbon atoms such as a 2-pentenyl group; or a cycloalkyl group having 3 to 10 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group and a cyclooctyl group.
The alkyl group having 1 to 20 carbon atoms, the aryl group having 6 to 12 carbon atoms, the alkenyl group having 2 to 10 carbon atoms and the cycloalkyl group having 3 to 10 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, Isopropoxy group, n-butoxy group, tert-butoxy group, sec-butoxy group,
C1-C10 alkoxy groups such as n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-decyloxy group; methoxymethoxy group, ethoxymethoxy group, propoxymethoxy group , A methoxyethoxy group, an ethoxyethoxy group, a propoxyethoxy group, a methoxypropoxy group, an ethoxypropoxy group, a methoxybutoxy group, an ethoxybutoxy group and the like, an alkoxyalkoxy group having 2 to 12 carbon atoms; a methoxymethoxymethoxy group, a methoxymethoxyethoxy group, An alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms such as a methoxyethoxymethoxy group, a methoxyethoxyethoxy group, an ethoxymethoxymethoxy group, an ethoxymethoxyethoxy group, an ethoxyethoxymethoxy group, an ethoxyethoxyethoxy group; Ryloxy group; aryl group having 6 to 12 carbon atoms such as phenyl group, tolyl group, xylyl group and naphthyl group; aryloxy group having 6 to 12 carbon atoms such as phenoxy group, tolyloxy group, xylyloxy group and naphthyloxy group; cyano Group; nitro group, hydroxy group; tetrahydrofuryl group; methylsulfonylamino group, ethylsulfonylamino group, n-propylsulfonylamino group, isopropylsulfonylamino group, n-butylsulfonylamino group, tert-butylsulfonylamino group, sec- C1-C6 alkylsulfonylamino groups such as butylsulfonylamino group, n-pentylsulfonylamino group, n-hexylsulfonylamino group; halogen atoms such as fluorine atom, chlorine atom, bromine atom; methoxycarbonyl group, ethoxycarbonyl Base, -C2-C7 alkoxy such as propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, tert-butoxycarbonyl group, sec-butoxycarbonyl group, n-pentyloxycarbonyl group, n-hexyloxycarbonyl group Carbonyl group: methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, tert-butylcarbonyloxy group, sec-butylcarbonyloxy group, n-pentylcarbonyl group An oxy group, an alkylcarbonyloxy group having 2 to 7 carbon atoms such as an n-hexylcarbonyloxy group; a methoxycarbonyloxy, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group,
C2-C7 such as isopropoxycarbonyloxy group, n-butoxycarbonyloxy group, tert-butoxycarbonyloxy group, sec-butoxycarbonyloxy group, n-pentyloxycarbonyloxy group, n-hexyloxycarbonyloxy group It may be substituted with an alkoxycarbonyloxy group or the like.

R ₅ and R ₆ may be cyclized to form a hydrocarbon ring or a heterocycle. Of these, an alkyl group having 1 to 5 carbon atoms is particularly preferable. In the general formula [2], salts of the hydroxy group, carboxylic acid group, and sulfonic acid group represented by X include Na ⁺ , Li ⁺ , and K.
Inorganic cations such as ⁺ or P ⁺ (phenyl) ₄ , N ⁺
_{(C 2 H 5) 4,} N + (C 4 H 9 (n)) 4, ( phenyl -N ⁺⁾
It represents a cation such as an organic cation such as (CH ₃ ) ₃ .

The metal of the metal salt is not particularly limited as long as it is a metal capable of forming a chelate compound with an azo compound which is a ligand, but nickel, cobalt, iron, ruthenium, rhodium, palladium, copper, osmium. , Transition elements such as iridium, platinum and zirconium are preferable,
Nickel, cobalt and palladium are particularly preferable.

As the nitrogen-containing heterocycle A, a pyridine ring,
1,2,4-thiadiazole ring, 1,3,4-thiadiazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, isoxazole ring and the like, which may have a substituent, Such substituents include alkyl groups, alkoxy groups, thioalkoxy groups, arylthio groups, aryloxy groups, aralkyl groups, aryl groups, halogen atoms, cyano groups, nitro groups,
Examples thereof include an ester group, a carbamoyl group, an acyl group, an acylamino group, a sulfamoyl group, a sulfinic acid group, an amino group, a hydroxyl group, a phenylazo group, a pyridinoazo group, and a vinyl group, and these substituents further have a substituent. May be. Among these substituents, preferred are a hydroxyl group, a halogen atom, a cyano group, a nitro group, an optionally substituted alkyl group having 1 to 25 carbon atoms, and an alkoxy group having 1 to 25 carbon atoms. Group, carbon number 1 to
25 thioalkoxy group, C 6-30 arylthio group, C 1-25 alkylsulfamoyl group, C 6-30 phenylsulfamoyl group, C 1-
25 alkylsulfinic acid groups, C6-30 phenylsulfinic acid groups, C6-30 pyridinoazo groups, C2-26 ester groups, C2-26 alkylcarbamoyl groups, C6-C6 30 phenylcarbamoyl group, C2-C26 acyl group, C1-2
5 acylamino group, -NR ⁷ R ⁸ (R ⁷ and R ⁸ each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 25 carbon atoms or a phenyl group, R ⁷ and R ⁸ may combine with each other to form a 5- or 6-membered ring.), —CR ⁹ ═C (CN) R
¹⁰ (R ⁹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ¹⁰ represents a cyano group or an alkoxycarbonyl group having 2 to 7 carbon atoms) and the like, and more preferably a halogen atom and the like. And an optionally substituted alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a thioalkoxy group having 1 to 10 carbon atoms, and a halogen atom.

Ring B may have a substituent other than the --NR ⁵ R ⁶ group and the --X group, and such a substituent is an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms; alkoxy. A group, preferably an alkoxy group having 1 to 10 carbon atoms; a halogen atom and the like, and an alkyl group thereof,
The substituent such as an alkoxy group may further have a substituent such as a halogen atom.

As one embodiment of the preferred compounds in the present invention, compounds of the general formula [2] having a substituent as shown in Table 6 are mentioned, and the compounds of the general formulas [8], [9],
Examples thereof include the compounds represented by [10], [11], [12] and [13].

[0036]

[Table 6]

[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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[0042]

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Then, the recording layer is formed on the substrate by spin coating a solution in which at least one kind of the dye 1 and at least one kind of the dye 2 are mixed. As a result, the single recording layer satisfies the condition described in claim 1 above. absorption edge at λ ₁ ,
The absorbance of the absorption edge in the lambda _2, is a condition that the ratio against respective absorption maxima correspond to the range of preferred extinction coefficient of the recording layer, both of the ratio of absorbance at a wavelength and the absorption edge of the absorption maximum, the recording The conditions corresponding to the preferable range of the refractive index of the layer are shown. Refractive index of the recording layer, the wavelength lambda ₁ in 2-3, the wavelength lambda ₂ 1.7 to 2.3, the extinction coefficient, at lambda _1, .02-0.
08 and λ ₂ are 0.02 to 0.1. Absorbance, absorption maximum, refractive index, extinction is small outside this range, 2
It tends to be difficult to obtain a sufficient degree of modulation at the wavelength.

The metal reflection layer is a metal film that efficiently reflects the laser light transmitted through the recording layer, and is 600 nm to 70 nm.
Since the reflectance does not decrease at 0 nm, the recording / reproducing wavelength ± 5
It is preferable that the refractive index of light in the wavelength region of nm is 0.1 to 0.2 and the extinction coefficient is 3 to 5. Preferred examples of the metal reflection film include a metal reflection film containing gold as a main component and a metal reflection film containing silver as a main component. Particularly, a metal reflection film containing silver as a main component is preferable. Further, in order to improve weatherability, additional elements such as rhodium, palladium, platinum, titanium, molybdenum, zirconium, tantalum, tungsten and vanadium may be added to silver in a range of 5 atomic% or less.
The thickness of the metal reflective layer is preferably 80 nm or more, and is preferably such a thickness that the deformation of the recording layer is not excessively suppressed or the recording sensitivity is not excessively deteriorated.

In the optical recording medium of the present invention, a protective layer is laminated on the reflective layer, which has the effect of preventing the formation of holes in the metal reflective layer of the recording portion and suppressing the asymmetry of deformation. I have. As the protective layer, an ultraviolet curable resin is preferable. The thickness of the protective layer is usually 1 μm or more, preferably 3 μm or more, so that the suppression of curing by oxygen or the like does not occur.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. Example 1 Groove depth 180 nm, groove width (half-value width of groove) 0.45 μm
A phthalocyanine dye represented by the following structural formula [14] and a metal-containing azo dye represented by the following structural formula [15] at a weight ratio of 1: 1 were used as a solvent on a polycarbonate substrate having a V-shaped guide groove (track pitch: 1.6 μm). A coating liquid was prepared by dissolving 2.2 wt% of the total weight of the dye in (octafluoropentanol), and the coating liquid was applied to the above polycarbonate substrate to form 900
Spin coat at rpm, then 1 in 80 ° C oven
A time-annealed recording layer was formed.

[0047]

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[0048]

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A silver reflection layer having a thickness of 100 nm was formed thereon by sputtering, and a UV curable resin (“SD-318” manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated thereon for about 3 μm and cured with an ultraviolet lamp. As a protective layer, a disc was formed. This disk was applied to a semiconductor laser evaluation machine (DDU-1000) to measure the optical disk characteristics at 780 nm (λ ₁ ). As a result, the reflectance is 65%
The recording characteristics at 4.8 m / s (recording power: 9 mW) all satisfied the Orange Book standard.

When this recording portion was reproduced by a semiconductor laser evaluation machine (made by Pulstec) of 680 nm (λ ₂ ), a good eye pattern could be reproduced with a reflectance of 48% and a 3T jitter of 15%. The groove depth of the coating film is 100
was nm. As a result, the maximum absorption (B ₁ , B ₂ ) of each dye, λ ₁ with respect to the absorbance at B ₁ , B ₂ ,
The results of the ratio of absorbance at λ ₂ and the 3T jitter (%) at 680 nm are shown in Table 7.

Example 2 The same experiment as in Example 1 was carried out except that the metal-containing azo dye of Example 1 was replaced with the metal-containing azo dye of the following structural formula [16]. The results are shown in Table-7.

[0052]

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Example 3 The same experiment as in Example 1 was conducted except that the metal-containing azo dye of Example 1 was replaced with the metal-containing azo dye of the following structural formula [17]. The results are shown in Table-7.

[0054]

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Example 4 The same experiment as in Example 1 was carried out except that the metal-containing azo dye of Example 1 was replaced with the metal-containing azo dye of the following structural formula [18]. The results are shown in Table-7.

[0056]

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Example 5 Example 1 was repeated except that the phthalocyanine dye of Example 1 was replaced with a phthalocyanine dye of structural formula [19] and the gold-containing azo dye of Example 1 was replaced with a metal-containing azo dye of structural formula [20]. The same experiment was performed. The results are shown in Table-7.

[0058]

[Chemical 21]

[0059]

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Example 6 Example 5 was repeated except that the metal-containing azo dye of Example 5 was changed to the metal-containing azo dye of the structural formula [21] and λ ₂ was changed to 640 nm.
The same experiment was performed. The results are shown in Table-7.

[0061]

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Comparative Example 1 The concentration in the coating solution was 1.1 wt% without using the metal-containing azo dye.
The same experiment as in Example 1 was performed except that the percentage was changed. As a result, characteristics satisfying the Orange Book were obtained at 780 nm, but no eye pattern was visible at 680 nm. The results are shown in Table-7.

[0063]

[Table 7]

[0064]

According to the present invention, the conventional 780 nm, 83
At the same time as recording / reproducing about 0 nm, 600-700 nm
It is possible to provide an optical disk capable of suitably reproducing even at a short wavelength.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tohwa Horie 1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi Chemical Corporation Yokohama Research Institute

Claims (4)

[Claims] 1. An optical recording medium in which at least a recording layer containing an organic dye, a metal reflective layer, and a protective layer are laminated in this order on a transparent substrate, and the following recording layer is formed on the transparent substrate. An optical recording medium satisfying the conditions (a) to (d). (A) First recording / reproducing wavelength λ ₁ (760 nm to 800 n
Absorption maximum B ₁ on the shorter wavelength side of 50 nm to 70 nm than m)
Having (B) The absorbance at λ ₁ ± 5 nm is 10 times that at B _1.
% Or less. (C) Second reproduction wavelength λ ₂ (600 nm to 700 nm)
Second absorption maximum B on the shorter wavelength side of 40 nm to 80 nm than
Having _two . (D) The absorbance at wavelength λ ₂ ± 5 nm is 1 of the absorbance at B _2.
0% or less. 2. The recording layer comprises one or more phthalocyanine dyes having a structural formula represented by the following general formula [1] and one or more metal-containing azo dyes having a structural formula represented by the following general formula [2]. The optical recording medium according to claim 1, wherein the optical recording medium is formed by mixing Embedded image (In the formula, A1 to A4 are an alkyl group which may have a substituent, a phenyl group, a cyclohexyl group, an alkoxy group,
Represents a phenoxy group and a cyclohexyloxy group, Z1
Z4 represents a halogen atom or a nitro group. n1-n4 represent the integer of 0-3. M is a divalent metal atom, trivalent or 4
It represents a valent substituted metal atom, a metal oxide or two hydrogen atoms. ) (In the formula, R ₅ and R ₆ each independently represent a hydrogen atom, which may be substituted, an alkyl group, an aryl group, an alkenyl group or a cycloalkyl group, and R ₅ and R ₆ are cyclized and carbonized. A hydrogen ring or a heterocycle may be formed, the nitrogen-containing heterocycle A and the benzene ring B may have a substituent, X is a hydroxy group, a carboxylic acid group, a sulfonic acid group or a salt thereof. Represents.) 3. The optical recording medium according to claim 1, wherein the metal reflection layer contains silver as a main component. 4. The method according to claim 1, wherein the protective layer is made of an ultraviolet curable resin.
The optical recording medium according to any one of claims 1 to 3, wherein