JPH08156408A - Optical recording medium - Google Patents

Abstract

PURPOSE: To obtain an optical recording medium enabling recording and reproduction by using light with a specific wavelength and enabling reproduction or recording and reproduction by using light with a specific shorter wavelength by adding a complex of an azo compd. represented by a specific formula and a metal and a dye having large absorption with respect to a specific wavelength to a recording layer. CONSTITUTION: A recording layer containing coloring matter, a reflecting layer and a protective layer are successively laminated on a transparent substrate to obtain an optical recording medium enabling recording and reproduction by light of 770-880nm and enabling reproduction or recording and reproduction by light of 620-690nm. The recording layer contains a complex of an azo compd. represented by formula and a metal and coloring matter having large absorption with respect to a wavelength of 720-850nm. In the formula, X is a residue forming a heterocyclic ring together with the nitrogen and carbon atoms bonded to X, Y is a residue forming an aromatic or heterocyclic ring together with two carbon atoms bonded to Y and Z is a group having active hydrogen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-plate type optical recording medium having a recording layer containing a dye, a reflecting layer and a protective layer on a transparent substrate, and particularly a recordable compact disc (CD-R).
Satisfies the Orange Book standard (ie, 7
Recording and reproduction is possible with light of 70 to 800 nm), and 620 to 69
The present invention relates to an optical recording medium capable of reproduction, recording and reproduction with 0 nm visible laser light.

[0002]

2. Description of the Related Art As an example of a single-plate type optical recording medium, a dye is used as a recording layer, and a metal reflective layer is provided on the recording layer to increase the reflectance, and a protective layer is further provided on the reflective layer. Optical recording media include, for example, Optical Data Storage 1989
Technical Digest Series Vol.1 45 (1989), JP-A-2-
132656, JP-A-2-168446, JP-A-3-215466, etc., and they are put on the market as a CD-R medium. This medium is characterized in that it can be recorded by a 780 nm semiconductor laser and can be reproduced by a commercially available CD player or CD-ROM player equipped with a 780 nm semiconductor laser.

However, the recording time for recording a large amount of information such as a digital moving image is as short as 15 minutes or less. Further, the capacity of the conventional medium becomes insufficient if the size of the conventional medium is reduced as the size of the device is further reduced. In the conventional CD-R medium, recording and reproducing were performed by using a semiconductor laser having a wavelength of around 780 nm, but recently, a semiconductor laser of 620 to 690 nm was developed, which enables recording and / or reproducing at higher density. , Development of a player for high-density media is under consideration.

At this time, it is desired that the conventional CD-R medium can be reproduced by a player compatible with at least a high density medium from the viewpoint of compatibility. The high-density player should be compatible with CDs, CD-ROMs and high-density media produced by the same method as the read-only media using Al (aluminum) as a reflective layer, which are currently on the market. The CD-R media is 620-
20% or more reflectance for 690nm light, preferably 25%
It is desired to have the above.

However, when the recorded conventional CD-R medium is reproduced by a semiconductor laser of 620 to 690 nm, the reflectance is as small as about 10%, the modulation degree is small, and the reflectance of the recording portion increases. High record (By the way,
High-to-low recording that reduces the reflectance of the recording area when reproduced with 780 nm light). Furthermore, a large distortion is observed in the recorded waveform. Due to these numerous drawbacks, conventional CDs
The -R medium was said to be difficult to reproduce with light at 620 to 690 nm. In addition, the reproduction light stability is also poor, for example
Even if the reproduction is performed with an output of 0.5 mW, there is a problem that the recording signal is deteriorated after being reproduced several times.

The reason is that the dye used in the recording layer of the above-mentioned conventional CD-R medium has a large absorption at 620 to 750 nm when measured with the film formed.
The reflectance at 620 to 690 nm is small, the degree of modulation is also small, and conversely the stability of the reproducing light is poor. The reason for waveform distortion is that the optical path length of the recording pit is 620 to 690 nm.
The present inventors presume that it is not uniform with respect to the light.

Japanese Patent Publication No. 5-67438 discloses a medium in which a metal complex of an azo compound of the present invention is used in a recording layer.
However, the medium is not intended for CD-R, and is intended for recording and reproduction with light of one wavelength, and satisfies the Orange Book, which is the characteristic effect of the present invention, Moreover, it is not possible to reproduce or record and reproduce even with light of 620 to 690 nm. For example, the medium described in Example 1 of the publication does not satisfy Orange Book because the recording layer has an absorption maximum near 800 nm. Also, the media of Examples 13 to 15 can record and reproduce with 633 nm light, but cannot record with 780 nm light.

On the other hand, WO 91/18950 discloses a medium in which a mixed dye of a cyanine dye and an azo metal chelate compound is used as a recording layer. The publication discloses that a dicarbocyanine (pentamethinecyanine) dye is used as a cyanine dye, and that the medium has absorption at 600 to 800 nm and is excellent in light resistance and moisture resistance. However, this medium is intended for recording and reproduction with a semiconductor laser of 780 nm, and when reproduced with light of 620 to 690 nm, the reflectance is small and the degree of modulation is small. In addition, the reproduction light stability is poor. The reason is that this uses a dicarbocyanine dye in the first place,
This is because it has a large absorption at ~ 720 nm. When dicarbocyanine dye is used, decreasing the blending ratio increases the reflectance for light of 620 to 690 nm,
In addition, the stability of the reproducing light is improved, but the recording sensitivity to the light of 780 nm is lowered and it cannot be put to practical use in any case.

[0009]

DISCLOSURE OF THE INVENTION The present inventors have found that 780 nm
It is possible to record and reproduce by using the light of 620 ~ 690nm
As a result of various studies to develop a medium capable of reproducing or recording and reproducing even with light, the present invention was achieved by controlling the absorption characteristics of the recording layer over a wide wavelength range, and by finding a dye that is easy to control. completed.

[0010]

According to the present invention, a recording layer containing a dye, a reflective layer and a protective layer are sequentially laminated on a transparent substrate, and recording and reproduction are possible with light of 770 to 800 nm. And an optical recording medium capable of reproducing or recording and reproducing even with light of 620 to 690 nm, the recording layer comprising a complex with a metal of an azo compound represented by the following general formula (1) An optical recording medium characterized by containing a dye having a large absorption at 720 to 850 nm, and

[0011]

Embedded image [In the formula (1), X represents a residue which forms a heterocycle with the nitrogen atom and carbon atom to which it is bonded,
Y represents a residue which forms an aromatic ring or a heterocycle together with the two carbon atoms to which it is bonded, and Z represents a group having active hydrogen. ] It is an optical recording medium having an absorption peak wavelength of 620 nm or less in a state where a metal complex film of an azo compound is formed, and has a reflectance of 65% or more for 780 nm light measured through a substrate and 680 nm and / or The reflectance for 635 nm light is
It is an optical recording medium whose content is 20% or more, and 680 nm and /
Or an optical recording medium having a reflectance of 25% or more for 635 nm light, and a dye having a large absorption at 720 to 850 nm is a dye selected from a cyanine dye, a phthalocyanine dye and a naphthalocyanine dye. And
In addition, the dye having a large absorption at 720 to 850 nm is an optical recording medium in which a tricarbocyanine dye is used.
Phthalocyanine is a dye with large absorption at ~ 850 nm.
An optical recording medium that is a naphthalocyanine dye.

The present invention will be described in detail below. The transparent substrate used in the optical recording medium of the present invention has a light transmittance of 85% or more for recording and reading signals,
Further, those having small optical anisotropy are preferable. Examples thereof include resin substrates known per se such as acrylic resins, polycarbonate resins, and polyolefin resins. These substrates may be plate-shaped or film-shaped, and may be circular or card-shaped. The surfaces of these substrates may have guide grooves or pits indicating recording positions. Such guide grooves and pits are preferably provided at the time of molding the substrate, but can be provided by providing an ultraviolet curable resin layer on the substrate.

In the general formula (1) used in the present invention,
In the represented azo compound, X is attached to it
Forms a heterocycle with carbon and nitrogen atoms
Represents a residue, specifically thiazole ring, benzothiazo
Ring, pyridobenzothiazole ring, benzopyridothiazo
Ring, pyridothiazole ring, pyridine ring, quinoline ring
Etc. are mentioned. These heterocycles are
It may have a substituent, and specific examples of the substituent include:
Alkyl group, halogenated alkyl group, aryl group, alcohol
Xy group, halogenated alkoxy group, aryloxy group,
Alkylthio group, halogenated alkylthio group, aryl
Thio group, aralkyl group, halogen atom, cyano group, nit
B group, ester group, carbamoyl group, acyl group, acyl
Amino group, sulfamoyl group, sulfonamide group, amine
Group, hydroxyl group, phenylazo group, pyridinoazo
Group, vinyl group, etc., and these substituents are further substituted
It may have a group. Preferred among the substituents on the heterocycle
The optional substituent has 1 to 25 carbon atoms which may have a substituent.
Alkyl group, which may have a substituent, has 1 to 25 carbon atoms
Fluoroalkyl group, carbon number 1 which may have a substituent
~ 25 alkoxy groups, halogen atoms, cyano groups, nitro
Group, alkyl having 1 to 25 carbon atoms, which may have a substituent
Thio group, C1-C25 fluorine which may have a substituent
Low alkylthio group, C1 which may have a substituent
~ 25 alkylsulfamoyl group, even if it has a substituent
Good C6-C30 phenylsulfamoyl group, substituent
Optionally having a phenylazo group, having a substituent
May be pyridinoazo group, ester group having 2 to 26 carbon atoms,
Carbamoyl group having 2 to 26 carbon atoms, acyl having 2 to 26 carbon atoms
Group, an acylamino group having 1 to 25 carbon atoms, a sulfur amino group having 1 to 25 carbon atoms
Lefonamide group, -NR ¹R²(R¹And R²Are each
Independently hydrogen atom, 1 to 2 carbon atoms which may have a substituent
5 alkyl groups or phenyl which may have a substituent
Represents a radical, R¹And R²Are together 5 membered ring or 6
A member ring may be formed), a hydroxyl group, -CR
³= C (CN) R^Four(R³Is a hydrogen atom or a C1-6
Represents an alkyl group, R^FourIs a cyano group or having 2 to 7 carbon atoms
(Representing an alkoxycarbonyl group) and the like.

In the azo compound represented by the general formula (1), Y represents a residue which, together with the two carbon atoms to which it is bonded, forms an aromatic ring or a heterocyclic ring. Include a residue forming a benzene ring, a naphthalene ring, a pyridine ring, a pyridone ring, a tetrahydroquinoline ring, a pyrazole ring, or the like. These aromatic rings or heterocycles may have a substituent, and as such a substituent, an alkyl group, a halogenated alkyl group, an aryl group, an alkoxy group, a halogenated alkoxy group, an aryloxy group, an alkylthio group, Halogenated alkylthio group, arylthio group, aralkyl group, halogen atom, cyano group, nitro group, ester group, carbamoyl group, acyl group, acylamino group, sulfamoyl group, sulfonamide group, amino group, hydroxyl group, phenylazo group, pyridinoazo group , Vinyl group, etc., and these substituents may further have a substituent. Among these substituents on the aromatic ring or the heterocycle, preferable substituents are an alkyl group having 1 to 25 carbon atoms which may have a substituent and a carbon number 1 which may have a substituent. ~ 25 fluoroalkyl group, an alkoxy group having 1 to 25 carbon atoms which may have a substituent, a fluoroalkoxy group having 1 to 25 carbon atoms which may have a substituent, a halogen atom, a cyano group, Nitro group, C1 to C25 fluoroalkylthio group which may have a substituent, C1 to C25 alkylsulfamoyl group which may have a substituent, and which may have a substituent Good C6-C30 phenylsulfamoyl group, optionally substituted phenylazo group, optionally substituted pyridinoazo group, C2-26 ester group, C2-C2 26 carbamoyl group, 2 to 26 carbon acyl group, 1 to 25 carbon atom Shiruamino group, a sulfonamido group having 1 to 25 carbon atoms, -N
R ¹ R ² (R ¹ and R ² are the same as defined above), hydroxyl group, —CR ³ ═C (CN) R ⁴ (R ³ and R ⁴ are the same as defined above) and the like.

In the azo compound represented by the general formula (1), Z is not particularly limited as long as it is a group having active hydrogen, but preferable ones are --OH, --COOH,
—SO ₃ H, —B (OH) ₂ , —NHSO ₂ R ⁵ (R ⁵ may have a hydrogen atom, an optionally substituted alkyl group having 1 to 25 carbon atoms, or a substituted group. represents a phenyl _{group), - CONH 2, -SO 2} NH 2, -NH 2 , and the like, particularly preferred are -OH, -COO
_{H, -SO 3 H, -NHSO 2} R 5 (R 5 is as defined above) can be mentioned. In addition, Z is -OH, -COOH, -S
When it is a group capable of dissociating into an anion such as O ₃ H, it may be used as it is when forming an azo metal complex compound, or may be used in the form of a salt with a cation. . Examples of such cations include inorganic cations such as Na ⁺ , Li ⁺ and K ⁺ , P ⁺ (C ₆ H ₅ ) ₄ and N ⁺ (C _{2
^{H 5) 4, N + (}} C 4 H 9) 4, C 6 H 5 N + (CH 3)
Organic cations such as ₃ are mentioned.

In the present invention, the azo compound is a metal.
Used as a complex of. Forms a complex with an azo compound
Examples of the metal having the capability include nickel and cobalt.
G, iron, ruthenium, rhodium, palladium, copper, male
Transition metals such as Mium, Iridium and Platinum are preferred and
In addition, nickel, cobalt, copper and palladium are preferable.
These are acetates, halides, BF_Four ^-Salt, etc.
Used in the form of Ni ²⁺, Co²⁺, Co³⁺, Cu²⁺, P
d²⁺Obtained as a complex coordinated to an azo compound as
It The metal complex of the azo compound used in the present invention is, for example,
Furukawa; Analytica Chimica Acta 140 (1982) 281-289
It can be formed according to the method described.

Preferred specific examples of the metal complex of the azo compound used in the present invention include the compounds shown in Tables 1 to 9 of JP-B-5-67438 and WO91 / 18950. In the present invention, when the metal complex of the azo compound is used alone in the recording layer, the recording sensitivity and the sensitivity to 780 nm light are increased.
There is a trade-off relationship between the reflectance of 35 and / or 680 nm light, and both cannot be satisfied. High reflectance and high sensitivity for 780nm light, and 635 and / or 6
In order to secure a reflectance of 20% or more, preferably 25% or more for 80 nm light, the absorption peak wavelength of the metal complex of the azo compound is 620 nm or less (when there are two or more absorption peaks, the longest A peak having a wavelength side) is preferable, and a dye having a large absorption at 720 to 850 nm is used in addition to the metal complex of the azo compound. Specific examples of the dye having a large absorption at 720 to 850 nm include cyanine dye, phthalocyanine dye, naphthalocyanine dye, benzoquinone dye, anthraquinone dye, and dithiol metal complex. In the above-mentioned dye, the absorption wavelength can greatly vary depending on the kind of the substituent and the metal, but in the present invention, it has a large absorption (maximum absorption or absorption close to maximum absorption) at 720 to 850 nm, Further, a dye having excellent compatibility with the metal complex of the azo compound is preferable.
Preferred examples include tricarbocyanine dyes, phthalocyanine dyes, and naphthalocyanine dyes. The absorption characteristics of the dye differ depending on the association state of the molecules, and the absorption characteristics differ depending on the solution, solid (membrane) and concentration, but the maximum absorption wavelength in the present invention is the value measured in the state where the membrane is formed by the dye alone. And As a typical example of the above-mentioned tricarbocyanine dye, the following general formula (2)
The indolenine tricarbocyanine dye represented by

[0018]

Embedded image (In the formula, P and P ′ each independently represent a residue forming a benzene ring or a naphthalene ring which may have a substituent, and A represents a linear or cyclic group which may have a substituent. Represents a linking group for forming tricarbocyanine of
R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , and R ¹¹ are each independently an optionally substituted alkyl group, an optionally substituted aryl group, an optionally substituted alkenyl group, or a substituted group. which may have been represents an cycloalkyl group, Q ^-
Represents an anion. As a specific example of A in the general formula (2), any one of the following general formulas (2a) to (2d) [Chemical Formula 4] is preferable.

[0019]

[Chemical 4] (In the formula, T represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, a cyano group, or a halogen atom). Further, specific examples of Q ^{+ in} the general formula (2) include I ⁻ and Br.
^-, Cl ^-, etc. a halogen anion, ClO ₄ ^-, BF ₄
^-, B (R) ₄ ^- or dithiol metal complex anion are preferred.

More specific examples of such indolenine type cyanine dyes are disclosed, for example, in JP-A-58-112790 and JP-A-58-114989.
And JP-A-59-85791 and JP-A-60-83236. Further, such a dye can be synthesized according to the method described in the above-mentioned patent. Representative examples of the above-mentioned phthalocyanine and naphthalocyanine dyes include dyes represented by the following general formula (3) [Chemical formula 5].

[0021]

Embedded image (In the formula, L ¹ , L ² , L ³ and L ⁴ each independently have a benzene ring which may have a substituent or a substituent together with the two carbon atoms to which it is bonded. Represents a residue that may form a naphthalene ring, as the substituent, an alkyl group which may have a substituent, an aryl group,
Examples thereof include an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a halogen atom, a hydroxyl group, a carboxyl group and a salt thereof, an ester group, a sulfonamide group, an amino group, an ammonium group, a sulfonic acid group and a salt thereof. M is metal, metal oxide, metal halide,
Representing a metal having a substituent) The absorption wavelengths of the phthalocyanine and naphthalocyanine dyes described above vary greatly depending on the type of substituents on the benzene ring or naphthalene ring and the type of central metal (M), but show a large absorption at 720 to 850 nm. Substituents and central metals (M) can be readily selected to have.

Specific examples of such phthalocyanine and naphthalocyanine dyes are described in, for example, JP-A-61-154888 and JP-A-61-1.
97280, JP 61-246091, JP 63-25092, JP 63
-57287, JP-A-63-57288, JP-A-63-57289, JP-A-63-5
7290, JP-A-63-62794 and the like. Further, these dyes can be synthesized by the method disclosed in the above patent.

In the present invention, a metal complex of an azo compound and
The weight ratio of the dye having a large absorption at 720 to 850 nm is preferably 99: 1 to 60:40. If the amount of the metal complex of the azo compound used is too large, the recording sensitivity at 780 nm is lowered, and if it is too small, the reflectance at 780 nm is less than 65%, which is not preferable. This recording sensitivity and 780nm
From the viewpoint of reflectance, the use ratio of the dye is 95: 5.
˜70: 30 is more preferable.

In the present invention, a mixture of the above-mentioned metal complex of an azo compound and a dye having a maximum absorption at 700 to 850 nm is contained directly on a substrate or through an inorganic or organic undercoat layer. A recording layer is provided. The method for providing the recording layer includes, for example, a spin coating method, a dipping method, a spraying method, a vapor deposition method and the like, but the spin coating method is simple and preferable. As a coating solvent for forming a film by the spin coating method, tetrafluoropropanol, octafluoropentanol,
Tetrachloroethane, bromoform, dibromoethane,
Diacetone alcohol, methyl cellosolve, ethyl cellosolve, methyl lactate, 3-hydroxy-3-methyl-2-butanone, octane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane and the like are preferable. When forming the recording layer, a binder may be used together if necessary. Preferred binders are polyvinyl alcohol, polyvinylpyrrolidone, nitrocellulose,
Examples thereof include cellulose acetate, ketone resins, acrylic resins, polyvinyl butyral, and polycarbonate. The thickness of the recording layer is usually 50 nm to 1 μm, preferably 70 nm to 500 nm
Is.

In the present invention, a reflective layer is provided on the recording layer containing the above dye. As the reflective layer, gold,
Metals such as silver, aluminum, copper and platinum and alloys containing these metals are used. The thickness of the reflective layer is usually 40 nm ~
It is 300 nm, preferably 60 nm to 200 nm. Further, a known inorganic or organic intermediate layer may be provided between the recording layer and the reflective layer to improve the reflectance and the recording characteristics. Furthermore,
In the present invention, in order to protect the recording layer and the reflective layer,
A protective layer may be provided on the reflective layer. As a protective layer,
An ultraviolet curable acrylic resin, an ultraviolet curable epoxy resin, a silicone hard coat resin, etc. are used.
Further, an ultraviolet curable resin, an inorganic thin film, or the like may be formed on the mirror surface side of the substrate to protect the surface and prevent adhesion of dust and the like.

The optical recording medium of the present invention thus obtained can be used for recording and reproduction by focusing laser light on the recording layer. The medium of the present invention can be recorded with a laser beam of 780 nm and has a reflectance of 65%.
As described above, the Orange Book standard, which is the standard for CD-R, is satisfied. Furthermore, the reflectance for light of 620 to 690 nm is
20% or more is obtained, and it can be played back even with the next-generation high-density optical disc player equipped with a 620 to 690 nm laser. The wavelength of light used for the next high-density player is 620 to 690 nm, and the wavelength of laser for practical use is, for example, around 635 nm or 680 nm.

[0027]

EXAMPLES The present invention will be described in detail below with reference to examples, but these are merely examples and the technical scope of the present invention is not limited thereto. Example 1 An azo compound shown below was formed in the center of the grooved surface of an injection-molded polycarbonate substrate having a spiral groove (depth 140 nm, width 0.4 μm, pitch 1.2 μm) having a thickness of 1.2 mm and a diameter of 120 mm. The Ni complex of (A ₁ ) and the tricarbocyanine dye (B ₁ ) [Chemical Formula 6] are used in a weight ratio of 90: 1.
A 3.5 wt% octafluoropentanol solution of the formulation of 0 was dropped, and the resin substrate was rotated to form a recording layer on the resin substrate. Then, a gold thin film having a thickness of 80 nm was formed as a reflective layer on the recording layer by sputtering.

Further, an ultraviolet curable resin (S
D-17, manufactured by Dainippon Ink Co., Ltd.) was spin-coated and irradiated with ultraviolet rays to form a protective layer having a film thickness of 5 μm, thereby manufacturing an optical recording medium. Incidentally, the azo metal complex of (A ₁ ) has an absorption peak wavelength of 580 nm in the state of forming a film and has a large absorption at 500 to 600 nm, and the cyanine dye of (B ₁ ) has an absorption peak wavelength of 800 nm. It has a large absorption at 720 to 850 nm.

[0029]

[Chemical 6] A drive equipped with a semiconductor laser having an oscillation wavelength of 780 nm while placing this optical recording medium on a turntable and rotating at a linear velocity of 2.8 m / s (Philips CDD-521).
While controlling the laser beam to focus on the recording layer on the groove through the substrate, while recording the FM modulation signal while changing the recording laser power, the laser output was set to 1 mW using the same device. The recorded signal was read. The error rate was the smallest at the laser output of 9 mW (optimum recording power), which was 3 × 10 ^-3 . Also, it was confirmed that the unrecorded portion had a reflectance of 70%, a jitter of 24 ns, and a sufficiently large degree of modulation (details are summarized in [Table 2]), so that extremely good recording and reproducing could be performed. or,
Almost no distortion was observed in the reproduced waveform.

Next, a signal was reproduced from this recorded medium by a high density player equipped with a 635 nm semiconductor laser. The reflectance was 30%, the degree of modulation was large, and the reflectance of the recording portion was high to low recording.
In addition, both the error rate and the jitter were small, very good reproduction was possible, and there was no problem in reproduction light stability. Furthermore,
When reproduced with a player equipped with a 680 nm semiconductor laser, the reflectance of the unrecorded part was 26%, high to low recording, the degree of modulation was large, and the error rate and jitter were small and very good reproduction was possible.

Examples 2 to 7 Azo compounds (A) (A _{1 to} A ₅ ) described in [Table 1]
Metal (M) dye having a large absorption in the complex and _{700~850nm (B) (B 1 ~B} 4), making the medium in accordance with Example 1 except for using [Formula 7], and evaluated. 780nm and 635n
The results of regeneration at m are summarized in [Table 2]. All of the media recorded at high to low, had a small error rate and a small jitter at 780 nm and 635 nm, were capable of excellent reproduction, and had no problem in reproduction light stability.

[0032]

[Chemical 7] Comparative Example 1 A medium was prepared according to Example 5 of WO 91/18950 (a metal complex of an azo compound and a dicarbocyanine dye were used at a ratio of 40:60) and evaluated in the same manner as in Example 1. Recording and playback at 780nm was very good, but 6
In the reproduction at 35 nm, the reflectance was as small as 9%, the modulation was hardly obtained, and the reproduction was impossible. The maximum absorption wavelength of the film of the dicarbocyanine dye formed is 690 nm, which has a large absorption at 600 to 720 nm.

Comparative Example 2 A medium was prepared and evaluated in the same manner as in Comparative Example 1 except that the metal complex of the azo compound and the dicarbocyanine dye in Comparative Example 1 were used in a weight ratio of 25:75. The reflectance of the unrecorded portion at 635 nm was 30%, but at 780 nm, almost no recording was possible even when the recording power was 15 mW.

Comparative Examples 3 and 4 Medium according to Example 1 except that the metal (M) complex of the azo compound (A) shown in Table 1 and the dye (B) having a large absorption at 700 to 850 nm were used. Was made and evaluated. The results are summarized in [Table 2] together with other examples. The medium of Comparative Example 3 could not be recorded even at a recording power of 780 nm and a recording power of 15 mW. Although the medium of Example 4 had high sensitivity, it had a low reflectance at 780 nm and could not be reproduced by a CD-ROM player.

[0035]

[Table 1] * Usage ratio: Metal complex of azo compound: Additive dye (B)

[0036]

[Table 2] It should be noted that the degree of modulation is usually 0.6 or more.

Example 8 Using the medium of Example 1, recording and reproduction were carried out using a drive equipped with a 680 nm semiconductor laser and a drive equipped with a 630 nm He-Ne laser. Good recording and playback were possible with both drives.

[0038]

DESCRIPTION OF THE INVENTION In the present invention, as is clear from the description of the embodiments and the comparative examples, the optical recording comprising a recording layer containing a dye, a reflective layer and a protective layer are sequentially laminated on a substrate. In the medium, 720-
By using a dye that has an absorption maximum at 850 nm,
Recording and reproduction is possible with 80 nm light (satisfies the Orange Book standard), and reproduction or recording and reproduction is possible using a 620-690 nm laser.

(72) Inventor Sumio Hirose, 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Keisuke Soma, 1190, Kasama-cho, Sakae-ku, Yokohama, Kanagawa (72) Inventor Misawa Denmi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (7)

[Claims] 1. A transparent substrate on which a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated, and 770 to 800 n
Recording and reproduction is possible with m light and 620-690nm
In the optical recording medium capable of reproducing or recording and reproducing even with the light, the recording layer has a large absorption at 720 to 850 nm with a complex of a metal of an azo compound represented by the following general formula (1) [Chemical formula 1]. An optical recording medium containing a dye having Embedded image [In the formula (1), X represents a residue which forms a heterocycle with the nitrogen atom and carbon atom to which it is bonded,
Y represents a residue which forms an aromatic ring or a heterocycle together with the two carbon atoms to which it is bonded, and Z represents a group having active hydrogen. ] 2. The optical recording medium according to claim 1, which has an absorption peak wavelength of 620 nm or less when a film of a metal complex of an azo compound is formed. 3. The optical recording medium according to claim 2, wherein the reflectance for light of 780 nm measured through the substrate is 65% or more, and the reflectance for light of 680 nm and / or 635 nm is 20% or more. 4. The optical recording medium according to claim 3, which has a reflectance of 25% or more for light of 680 nm and / or 635 nm. 5. The optical recording medium according to claim 1, wherein the dye having a large absorption at 720 to 850 nm is a dye selected from a cyanine dye, a phthalocyanine dye and a naphthalocyanine dye. 6. The optical recording medium according to claim 1, wherein the dye having a large absorption at 720 to 850 nm is a tricarbocyanine dye. 7. The optical recording medium according to claim 1, wherein the dye having a large absorption at 720 to 850 nm is a phthalocyanine or naphthalocyanine dye.