JPH08108623A - Optical recording medium - Google Patents

Abstract

PURPOSE: To enable the reproduction of recording by near infrared laser or red laser by adding an azo compd. having absorption max. at a specific wavelength represented by specific formula to a recording layer. CONSTITUTION: A recording layer 2, a reflecting layer and a protective layer 4 are provided on a substrate 1. An azo compd. having absorption max. at a wavelength of 450-630nm represented by formula (R1 -R5 are independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a substituted or non-substituted alkyl group, an alkoxy group or an aryl group and R1 is not a nitro group, R6 -R11 are independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a sulfone group, a substituted or non- substituted alkyl group, an alkoxy group, an aryl group, an acyl group or an alkylcarboxyl group) is added to the recording layer 2. By this constitution, an optical recording medium enabling the reproduction of recording by near infrared laser with a wavelength of 780nm and red laser with a wavelength of 635nm or 680nm is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is capable of recording and / or reproducing with an optical recording medium, particularly with a red laser having a wavelength of 620 to 690 nm, and recording and / or reproducing with a near infrared laser having a wavelength of 770 to 830 nm. An optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium having a reflective layer on a substrate, a recordable or recordable CD corresponding to the compact disc (hereinafter abbreviated as CD) standard has been proposed [eg Nikkei Electronics, No. 465, P.I. 10
7, January 23, 1989]. This optical recording medium is shown in FIG.
The recording layer 2, the reflective layer 3, and the protective layer 4 are formed on the substrate 1 as shown in FIG.
Are formed in this order. When the recording layer of this optical recording medium is irradiated with a laser beam such as a semiconductor laser with high power, the recording layer undergoes a physical or chemical change,
Record information in the form of pits. Information on the pits can be reproduced by irradiating the formed pits with low-power laser light and detecting the reflected light. Generally, a wavelength of 770 to 830 nm is used for recording / reproducing of such an optical recording medium.
The near-infrared semiconductor laser is used and conforms to the CD standards of Red Book, Orange Book, etc., and therefore has the feature of being compatible with CD players and CD-ROM players.

Recently, development of semiconductor lasers having a wavelength shorter than 770 nm has progressed, and red semiconductor lasers having wavelengths of 680 nm and 630 nm have been put into practical use [eg Nikkei Electronics, No. 592, P.I. 65, 1993
October 11, issue]. By reducing the beam spot by shortening the wavelength of the recording / reproducing laser, a high-density optical recording medium becomes possible. Large-capacity optical recording media capable of storing moving images have been developed by shortening the wavelength of semiconductor lasers and data compression technology [eg, Nikkei Electronics, No. 589, P.P. 55, August 30, 1993]. Such a high-density optical recording medium can record a large amount of data such as a moving image, and is expected to be used for a video CD and the like [eg, Nikkei Electronics, No. 594, P.I. 169, November 8, 1993]. Further, in JP-A-2-278519, 68
780nm with high sensitivity recording with 0nm short wavelength laser
High-sensitivity and high-speed recording has been proposed by the method of reproducing by.

On the other hand, Japanese Patent Laid-Open No. 6-40162 proposes an optical recording medium capable of recording / reproducing with a short wavelength laser. This medium uses an indocarbocyanine dye in the recording layer, and a 630 nm semiconductor laser or He.
Recording is possible with a Ne laser. A 490 nm blue / green semiconductor laser having a wavelength shorter than 630 nm has also been studied, but has not yet reached the stage of practical application [eg, Applied Physics Letter,
P. 1272-1274, Vol. 59 (1991) and "Nikkei Electronics" No. 552, P.I. 90,1
April 27, 1992]. From such a background, the recording / reproducing wavelength of the optical recording medium tends to be shortened to around 630 nm. Therefore, it is necessary to develop an optical recording medium corresponding to this, and further, a compatible optical recording medium compatible with the conventional 780 nm is also desired.

[0005]

However, according to our study, in the conventional optical recording medium, the organic dye used in the recording layer has a large absorption at a wavelength of 620 to 690 nm and a small refractive index, so that the reflectance is low. It was found that reproduction with a red laser having a wavelength of 680 nm or 630 nm is impossible. The object of the present invention is to provide a wavelength of 680 or 63
Recording and / or reproduction is possible with a 0 nm red laser and a 780 nm near infrared laser (commercially available CD
It is intended to provide an optical recording medium that can be reproduced or recorded / reproduced by a player).

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have proposed the present invention.

That is, the present invention is an optical recording medium having a recording layer, a reflective layer and a protective layer on a substrate, and the wavelength of 450 to 630n represented by the formula (1)
An optical recording medium containing an azo compound having an absorption maximum at m,

[0008]

Embedded image [Wherein R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, an alkoxy group, or an allyl group. However, two or three of them are cyano groups, and R ₁ is not a nitro group. R ₆ , R ₇ , R ₈ , R ₉ ,
R ₁₀ and R ₁₁ are each independently a hydrogen atom, a halogen atom,
Hydroxy group, carboxyl group, sulfone group, substituted or unsubstituted alkyl group, alkoxy group, allyl group, acyl group, alkylcarboxyl group, aralkyl group, alkylcarbonylamino group, alkylsulfonamino group, alkylamino group, sulfonamide group Represents an amino group, an alkylcarbonyl group, an alkylsulfone group, and a phenyl group, and R ₇ and R ₁₀ , R ₉ and R _11, and R ₁₀ and R ₁₁ may form a ring via a linking group. ] In the recording layer, the compound represented by the formula (1) and a wavelength of 650 to 9
An optical recording medium containing a light absorbing compound having an absorption maximum at 00 nm, and an optical recording medium having a weight ratio of the light absorbing compound having an absorption maximum at a wavelength of 650 to 900 nm of 0.1 to 50%. In addition, wavelength 620 to 690 nm
The reflectance measured from the substrate side with respect to the light selected from the red laser is 20% or more, and the wavelength is 620 to 690n.
The optical recording medium is at least reproducible by a red laser having a wavelength of 620 to 690 nm and has a reflectance of 20% or more measured from the substrate side with respect to light selected from a red laser having a wavelength of 620 to 690 nm. It is an optical recording medium that can be recorded and / or reproduced by a red laser, and has a reflectance of 65 with respect to light selected from a near infrared laser having a wavelength of 770 to 830 nm, measured from the substrate side.
% Or more and an optical recording medium capable of recording and / or reproducing with a near infrared laser selected from 770 to 830 nm.

According to the present invention, the wavelength of 620 to 690 can be obtained by using the above-mentioned azo compound or a mixture of the azo compound and a compound having an appropriate light absorption in the recording layer.
nm red laser can record and / or reproduce, and
An optical recording medium capable of reproduction or recording / reproduction with a laser selected from 770 to 830 nm is realized.

Each constituent element of the present invention will be described in detail below. The optical recording medium of the present invention has a recording layer and a reflective layer on a substrate. The optical recording medium refers to both a read-only optical read-only medium in which information is recorded in advance and an optical recording medium in which information can be recorded and reproduced. However, here, as a suitable example, an optical recording medium capable of recording and reproducing the latter information, particularly an optical recording medium in which a recording layer, a reflective layer and a protective layer are formed in this order on a substrate will be described. This optical recording medium has a four-layer structure as shown in FIG. That is, the recording layer 2 is formed on the substrate 1, the reflective layer 3 is provided in close contact therewith, and the protective layer 4 further covers the reflective layer 3 thereon.

Basically, the material of the substrate should be transparent at the wavelengths of the recording light and the reproducing light. For example, a polymer material such as a polycarbonate resin, a vinyl chloride resin, an acrylic resin such as polymethylmethacrylate, a polystyrene resin, an epoxy resin, or an inorganic material such as glass is used. These substrate materials are formed into a disk shape by injection molding or the like. If necessary, grooves may be formed on the surface of the substrate.

The azo compound represented by the formula (1) (Chemical Formula 3) contained in the recording layer has a λmax of around 500 nm,
Since the refractive index at 620 to 690 nm is large and the absorbance is small, a large reflectance can be obtained. Also, 770-830n
Since the refractive index at m is large and the absorption is small, it can be reproduced by a CD player or a CD-ROM player equipped with a semiconductor laser of 770 to 830 nm which is currently used.

[0013]

Embedded image [Wherein R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, an alkoxy group, or an allyl group. However, two or three of them are cyano groups, and R ₁ is not a nitro group. R ₆ , R ₇ , R ₈ , R ₉ ,
R ₁₀ and R ₁₁ are each independently a hydrogen atom, a halogen atom,
Hydroxy group, carboxyl group, sulfone group, substituted or unsubstituted alkyl group, alkoxy group, allyl group, acyl group, alkylcarboxyl group, aralkyl group, alkylcarbonylamino group, alkylsulfonamino group, alkylamino group, sulfonamide group Represents an amino group, an alkylcarbonyl group, an alkylsulfone group, and a phenyl group, and R ₇ and R ₁₀ , R ₉ and R _11, and R ₁₀ and R ₁₁ may form a ring via a linking group. The halogen atom is fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine.

As the substituted or unsubstituted alkyl group,
Linear or branched alkyl group, alkoxyalkyl group,
Alkoxyalkoxyalkyl group, alkoxyalkoxyalkoxyalkyl group, alkoxycarbonylalkyl group, alkoxycarbonyloxyalkyl group, alkoxyalkoxycarbonyloxyalkyl group, hydroxyalkyl group, hydroxyalkoxyalkyl group, hydroxyalkoxyalkoxyalkyl group, cyanoalkyl group, acyloxyalkyl A group, an acyloxyalkoxyalkyl group and an alkyl halide.

The linear or branched alkyl group is a hydrocarbon group having 1 to 20 carbon atoms, and in consideration of workability by coating on a polycarbonate, acryl, epoxy, polyolefin substrate or the like, a methyl group, an ethyl group or a propyl group. ,
n-butyl group, n-hexyl group, 4-ethylpentyl group, 2-ethylhexyl group, n-octyl group, 3, 5,
Examples include 5-trimethylhexyl group, 2-methyl-1-iso-propylpropyl group, 3-methyl-1-iso-propylbutyl group, 3-methyl-1-iso-butylbutyl group and the like.

As the alkoxyalkyl group, a methoxymethyl group, an ethoxymethyl group, a propoxymethoxy group,
Butoxymethyl group, methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, n-hexyloxyethyl group, 4-methylpentoxyethyl group,
1,3-dimethylbutoxyethyl group, 2-ethylhexyloxyethyl group, n-octyloxyethyl group,
Carbon number 2 such as 3,5,5-trimethylhexyloxyethyl group, 2-methyl-1-iso-propyloxyethyl group, 3-methyl-1-iso-propylbutyloxyethyl group, 2-ethoxy-1-methylethyl group, 3-methoxybutyl group There are 20 types. Examples of alkoxyalkoxyalkyl groups include methoxyethoxyethyl group, ethoxyethoxyethyl group, propoxyethoxyethyl group, butoxyethoxyethyl group, hexyloxyethoxyethyl group, 1,2-dimethylpropoxyethoxyethyl group, 3-methyl-1-iso. -Butylbutoxyethoxyethyl group, 2-methoxy-1-methylethoxyethyl group, 2-butoxy-1-methylethoxyethyl group,
2- (2′-ethoxy-1′-methylethoxy) -1-methylethyl group and the like can be mentioned.

Examples of alkoxyalkoxyalkoxyalkyl include a methoxyethoxyethoxyethyl group, an ethoxyethoxyethoxyethyl group and a butoxyethoxyethoxyethyl group. Examples of the alkoxycarbonylalkyl group include a methoxycarbonylmethyl group, an ethoxycarbonylmethyl group, a butoxycarbonylmethyl group, a methoxycarbonylethyl group, an ethoxycarbonylethyl group, a butoxycarbonylethyl group, and the like. Examples of the alkoxycarbonyloxyalkyl group include a methoxycarbonyloxyethyl group, an ethoxycarbonyloxyethyl group, a butoxycarbonyloxyethyl group and the like. Examples of the alkoxyalkoxycarbonyloxyalkyl group include a methoxyethoxycarbonyloxyethyl group, an ethoxyethoxycarbonyloxyethyl group, a butoxyethoxycarbonyloxyethyl group, and the like.

Examples of the hydroxyalkyl group are 2-hydroxyethyl group, 4-hydroxyethyl group, 2-hydroxy-3-methoxypropyl group, 2-hydroxy-3-chloropropyl group, 2-hydroxy-3-ethoxypropyl group and 3-butoxy-2-hydroxy group. Examples thereof include a propyl group, a 2-hydroxy-3-phenoxypropyl group, a 2-hydroxypropyl group and a 2-hydroxybutyl group. Examples of the hydroxyalkoxyalkyl group include a hydroxyethoxyethyl group, 2- (2′-hydroxy-1′-methylethoxy) -1-methylethyl group and the like, and examples of the hydroxyalkoxyalkoxyalkyl group include a hydroxyethoxyethoxyethyl group, Examples thereof include a 2 '-(2 "-hydroxy-1" -methylethoxy) -1'-methylethoxy] ethoxyethyl group.

Examples of the cyanoalkyl group include 2-cyanoethyl group, 4-cyanoethyl group, 2-cyano-3-methoxypropyl group, 2-cyano-3-chloropropyl group, 2-cyano-3-ethoxypropyl group, 3-butoxy-2-cyanopropyl group and 2-cyano-3 group. -Phenoxypropyl group, 2-cyanopropyl group, 2-cyanobutyl group and the like.

Examples of the acyloxyalkyl group are acetoxyethyl group, propionyloxyethyl group, butyryloxyethyl group, valeryloxyethyl group, 1-ethylpentylcarbonyloxyethyl group, 2,4,4-trimethylpentylcarbonyl group. Oxyethyl group and the like, examples of the acyloxyalkoxyalkyl group, acetoxyethoxyethyl group, propionyloxyethoxyethyl group, valeryloxyethoxyethyl group,
Examples thereof include a 1-ethylpentylcarbonyloxyethoxyethyl group, a 2,4,4-trimethylpentylcarbonyloxyethoxyethyl group, and examples of the acyloxyalkoxyalkoxyalkyl group include an acetoxyethoxyethoxyethyl group and a propionyloxyethoxyethoxyethyl group. , A valeryloxyethoxyethoxyethyl group, a 1-ethylpentylcarbonyloxyethoxyethyl group, a 2,4,4-trimethylpentylcarbonyloxyethoxyethoxyethyl group, and the like.

Examples of halogenated alkyl groups include chloromethyl group, chloroethyl group, 2,2,2-trifluoroethyl group, trifluoromethyl group, bromomethyl group,
Examples thereof include methyl iodide group.

In addition, alkoxy group, allyl group, acyl group, alkylcarboxyl group, aralkyl group, carboalkylamino group, sulfoalkylamino group, alkylamino group, sulfonamide group, amino group, alkylcarbonyl group, phenyl group, etc. Also in the above, it is possible to have a substituent similar to the above-mentioned alkyl group.

Examples of R ₇ and R ₁₀ or R ₉ and R ₁₁ forming a ring via a linking group include the following [Chemical Formula 4].

[0024]

[Chemical 4] Examples of R ₁₀ and R ₁₁ forming a ring via a linking group include:
The following may be mentioned.

[0025]

Embedded image

The content of the azo compound used in the present invention in the recording layer is not particularly limited, but is usually about 30 to 100% by weight. Further, the azo compound of the present invention is A-NH ₂
The aromatic amine represented by (A represents a substituted or unsubstituted aromatic residue) is diazotized by a conventional method, and BN (R ')-
R "(B represents a substituted or unsubstituted aromatic residue, R ', R" represents a hydrogen atom, or a substituted or unsubstituted alkyl group.)
It can be easily obtained by coupling with an aromatic amine represented by

In the present invention, in order to improve the recording sensitivity for 620 to 690 nm and 770 to 830 nm,
It is also a preferred embodiment to further use a light absorbing compound having a maximum absorption wavelength of 50 to 900 nm. in this case,
The amount used is based on the azo compound specified in the present invention.
Mix at a weight ratio of 0.1 to 50% (based on the total amount of both, the same applies below). If this light absorbing compound is much more than this, it is 630 to 690 nm and 770 to 830 nm.
There is a possibility that the absorption coefficient of the dye film at the point of becomes large and the reflectance of the reproducing characteristic is lowered. Also, if the addition amount is much less than this, 620 to 690 nm and 770
Since the absorption coefficient of the dye film at ˜830 nm is too small, the effect of improving the recording sensitivity is not sufficient. However, 690-7
A light absorbing compound having a sharp absorption maximum at 40 nm can be mixed in a weight ratio of 0.1 to 150%.

The light absorbing compound used for such purpose in the present invention includes pentamethine cyanine dyes, heptamethine cyanine dyes, squarylium dyes, azo dyes, naphthoquinone dyes, anthraquinone dyes,
Indophenol dye, phthalocyanine dye, naphthalocyanine dye, pyrylium dye, thiopyrylium dye, azulenium dye, triphenylmethane dye, xanthene dye, indanthrene dye, indigo dye, thioindigo dye, There are merocyanine dyes, thiazine dyes, acridine dyes, oxazine dyes, etc., but in short, 650 nm to 900 nm
It suffices to have a maximum absorption wavelength at. Particularly, those which can be mixed with the azo compound are preferable. Further, a plurality of these dyes may be mixed and used.

Among them, 1,3,3,1 ', 3', 3 '= hexamethyl-
2,2 '-(4,5,4', 5'-Dibenzo) indodicarbocyanine perchlorate, 3,3'-diethyl-2,2 '-(6,7,6', 7'-
Dibenzo) -thiadicarbocyanine iodide, 3,3 '
-Diethyl-2,2'-thiadicarbocyanine iodide, 1,1'-diethyl-2,2'-quinodicarbocyanine iodide, 3,3'-diethyl-2,2'-selena dicarbocyanine Iodide, 1,3'-diethyl-4,2'-quinoxadicarbocyanine iodide, 3,3 ', 9-triethyl-
2,2 '-(4,5,4', 5'-Dibenzo) thiadicarbocyanine bromide, 1,1'-diethyl-2,4'-quinodicarbocyanine iodide, 1,3'-diethyl- Cyanine dyes such as 4,2'-quinothiadicarbocyanine iodide are preferred. Further, phthalocyanine dyes such as the following [Chemical formula 6] and [Chemical formula 7], naphthalocyanine dyes, and azo dyes can also be preferably used.

[0030]

[Chemical 6]

[0031]

[Chemical 7] If necessary, additives such as a quencher and an ultraviolet absorber can be mixed or introduced as a substituent to these compounds and dyes. For example, the additives include those represented by the following formulas (2) to (8) [Chemical formula 8] to [Chemical formula 14].

[0032]

Embedded image

[0033]

[Chemical 9]

[0034]

[Chemical 10]

[0035]

[Chemical 11]

[0036]

[Chemical 12]

[0037]

[Chemical 13]

[0038]

Embedded image (However, in the above formula, A and A ′ are an atomic group forming a benzene ring or a substituted benzene ring or forming a naphthalene ring or a substituted naphthalene ring, and may be the same or different. These substituents may be singular or plural, and examples thereof include an alkyl group, an alkoxy group, a hydroxy group, a carboxyl group, a halogen atom, an allyl group, an alkylcarboxyl group, an alkylalkoxyl group and an aralkyl group. , An alkylcarbonyl group, a sulfonate alkyl group bonded to a metal ion, a nitro group, an amino group, an alkylamino group,
Examples thereof include a phenyl group and a phenylethylene group. R ₁₂
To R ₃₄ are a substituted or unsubstituted alkyl group, alkoxy group, hydroxy group, carboxyl group, halogen atom, allyl group, alkylcarboxyl group, alkylalkoxyl group, aralkyl group, alkylcarbonyl group, sulfonate alkyl bonded to a metal ion. Group, nitro group, amino group, alkylamino group, phenyl group, phenylethylene group and the like are preferable. M is Ni,
Transition metals such as Co, Mn, Cu, Pd and Pt are shown. M may have a charge and may have a salt structure with a cation. a represents the valence of the ionic substance and is a positive integer including 0. Z represents a cation, a = bc, and a =
It will be clear that when 0, b · c = 0 and Z does not exist, and the compound becomes a neutral compound. )

In the present invention, the above-mentioned compound / dye has a thickness of 50 on the substrate by a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method or a vacuum vapor deposition method.
A recording layer of ˜500 nm, preferably 100-150 nm is formed. Particularly in the coating method, a coating solvent in which a dye is dissolved or dispersed is used, and it is preferable to select a solvent that does not damage the substrate. For example,
Alcohol solvents such as methanol, aliphatic hydrocarbon solvents such as hexane and octane, cyclic hydrocarbon solvents such as cyclohexane, aromatic hydrocarbon solvents such as benzene, halogenated hydrocarbon solvents such as chloroform, dioxane, etc. The ether solvent, the cellosolve solvent such as methyl cellosolve, the ketone solvent such as acetone, the ester solvent such as ethyl acetate, etc. are used alone or in combination. The recording layer is not limited to a single layer, and a plurality of compounds may be formed in a multi-layer, or the compound may be dispersed in a polymer thin film or the like, preferably about 50% or more. The recording layer containing the azo compound and the recording layer containing the light absorbing compound may be different multilayer recording layers. When a solvent that does not damage the substrate cannot be selected, sputtering, chemical vapor deposition, vacuum vapor deposition, etc. are effective.

In the present invention, next, a reflective layer having a thickness of 50 to 300 nm, preferably 100 to 150 nm is formed on the recording layer. As the material of the reflective layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, Au, Al, A
g, Cu, Ti, Cr, Ni, Pt, Ta, Cr and P
The metal of d can be used alone or as an alloy. Among these, Au and Al have a high reflectance and are suitable as a material for the reflective layer. Other than the above, the following may be included. For example, Mg, Se, Hf, V, Nb,
Ru, W, Mn, Re, Fe, Co, Rh, Ir, C
u, Zn, Cd, Ga, In, Si, Ge, Te, P
Mention may be made of metals and semi-metals such as b, Po, Sn and Bi. Further, a material containing Au as a main component is preferable because a reflective layer having a high reflectance can be easily obtained. Here, the main component means that the content rate is 50% or more.
It is also possible to stack a low refractive index thin film and a high refractive index thin film alternately with a material other than metal to form a multilayer film and use it as a reflective layer. As a method of forming the reflective layer, for example,
The sputtering method, the chemical vapor deposition method, the vacuum vapor deposition method, etc. are mentioned.
Further, a reflection amplification layer or an adhesive layer may be provided between the recording layer and the reflection layer in order to increase the reflectance or improve the adhesion.

The optical recording medium of the present invention thus obtained is a medium having a recording layer and a reflective layer formed on a substrate.
The reflectance from the substrate side with respect to light having a wavelength selected from the range of 620 to 690 nm is preferably 20% or more, more preferably 30% or more, and 770
The reflectance from the substrate side with respect to light having a wavelength selected from the range of nm to 830 nm is preferably 65% or more, more preferably 70% or more.
D) Standard and Orange Book (CD-R) standard reflectance are satisfied. If these standards are satisfied, it can be satisfactorily reproduced even by a CD player that has been commercially available in the past.

In the present invention, a protective layer may be further formed on the reflective layer. The material of the protective layer is not particularly limited whether it is an organic substance or an inorganic substance as long as it protects the reflective layer from external force. Examples of the organic substance include a thermoplastic resin, a thermosetting resin, a UV curable resin, and the like. Among them, UV curable resin is preferable. Further, as the inorganic substance, SiO ₂ , SiN ₄ ,
MgF _2, SnO ₂ and the like.

These thermoplastic resins, thermosetting resins and the like can be formed by dissolving them in a suitable solvent, applying a coating solution, and drying. UV curable resin is
It can be formed as it is or by dissolving it in a suitable solvent to prepare a coating solution, applying the coating solution, and irradiating with UV light to cure the coating solution. As the UV curable resin, for example, an acrylate resin such as urethane acrylate, epoxy acrylate, polyester acrylate can be used. These materials may be used alone or as a mixture, and may be used not only as a single layer but also as a multilayer film. As a method of forming the protective layer, a coating method such as a spin coating method or a casting method, a sputtering method, a chemical vapor deposition method, or the like is used as in the recording layer, and among them, the spin coating method is preferable.

The red laser used in the present invention is 620 to 620.
Any laser having a wavelength of 690 nm may be used.
For example, there are dye lasers capable of wavelength selection in a wide range of the visible region, helium neon lasers having a wavelength of 633 nm, and high-power semiconductor lasers having a wavelength of 680 nm that have been recently developed. However, semiconductor lasers are preferable in consideration of mounting on a device. Is. The near infrared laser is 770
Any laser with a wavelength of ~ 830 nm can be used,
Semiconductor lasers used in commercially available CD players and CD recorders are suitable.

[0045]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. [Example 1] 0.2 g of the azo compound (A) represented by the formula (1) and Table 1 and a trimethine cyanine dye NK2929 (1,3,3,1 ', 3', 3'-) as a light absorbing compound.
Hexamethyl-2,2 '-(4,5,4', 5'-dibenzo) indocarbocyanine perchlorate) [manufactured by Japan Photosensitive Dye Research Institute] 0.02 g was dissolved in 10 ml of diacetone alcohol (Tokyo Kasei). , Prepare a dye solution. The substrate is made of polycarbonate resin and has a continuous guide groove (track pitch: 1.6 μm) and a diameter of 120 m.
A disk-shaped one with mφ and a thickness of 1.2 mm was used. A dye solution was spin-coated on this substrate at a rotation speed of 1500 rpm and dried at 70 ° C. for 2 hours to form a recording layer. On this recording layer, a Balzers sputtering device (CDI-90
0) was used to sputter Au to form a reflective layer having a thickness of 100 nm. Argon gas was used as the sputtering gas. The sputtering conditions were sputtering power of 2.5 kW and sputtering gas pressure of 1.0 × 10 ^-2 Torr. Further, an ultraviolet curable resin SD-17 (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the reflective layer and then irradiated with ultraviolet rays to form a protective layer having a thickness of 6 μm. Optical disk evaluation device DDU-1000 and KENWOOD manufactured by Pulstec Industrial Co., Ltd. equipped with a 680 nm red semiconductor laser head.
Linear velocity of 5.6 m / s, using an EFM encoder manufactured by
Recording was performed with a laser power of 10 mW. 635n after recording
m A signal was reproduced using an evaluation device equipped with a red semiconductor laser head, and the reflectance was measured. In addition, as a result of performing reproduction evaluation of this recorded sample with a commercially available CD player having a reproduction wavelength of 780 nm, good recording characteristics were shown.

[Examples 2 to 9] Optical recording media were prepared in the same manner as in Example 1 except that the azo compounds (B) to (I) shown in the formula (1) and [Table 1] were used. . As with Example 1, the manufactured medium was equipped with a 680 nm red laser head, an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd., and an EFM manufactured by KENWOOD.
Recording was performed at a linear velocity of 5.6 m / s and a laser power of 10 mW using an encoder. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

[Example 10] In Example 1, the azo compound (J) represented by the formula (1) and [Table 1] and a heptamethine cyanine dye NK125 (1, 3, as a light absorber).
3,1 ′, 3 ′, 3′-hexamethyl-2,2′-indotricarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] was used in the same manner except that 0.02 g was used. . The produced medium was recorded at a linear velocity of 2.8 m / s and a laser power of 7 mW using an optical disc evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 780 nm near-infrared semiconductor laser head and an EFM encoder manufactured by KENWOOD. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

Example 11 In Example 1, the azo compound (K) represented by the formula (1) and [Table 1] and the pentamethinecyanine dye NK2627 as a light absorbing compound are used.
(3,3'-diethyl-2,2 '-(6,7,6',
7'-dibenzo) thiadicarbocyanine iodide)
An optical recording medium was prepared in the same manner except that [manufactured by Japan Photosensitive Dye Research Institute] was used. The manufactured medium is an optical disk evaluation device DDU-1000 and KENWO manufactured by Pulstec Industrial Co., Ltd., which is equipped with a 780 nm near infrared semiconductor laser head.
Using an EFM encoder manufactured by OD, a linear velocity of 1.4 m /
s, the laser power was recorded at 7 mW. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

[Example 12] An optical recording medium was prepared in the same manner as in Example 1 except that the azo compound (L) represented by the formula (1) and [Table 1] was used. The produced medium is equipped with a 680 nm red laser head in the same manner as in Example 1, and is an optical disk evaluation device DDU- manufactured by Pulstec Industrial Co., Ltd.
Recording was carried out at a linear velocity of 5.6 m / s and a laser power of 10 mW using an EFM encoder manufactured by 1000 and KENWOOD. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

[Example 13] In Example 1, the azo compound (M) represented by the formula (1) and [Table 1] and a heptamethine cyanine dye NK125 (1, 3, as a light absorber) were used.
3,1 ′, 3 ′, 3′-hexamethyl-2,2′-indotricarbocyanine iodide) [manufactured by Japan Photosensitive Dye Research Institute] was used in the same manner except that 0.02 g was used. . The produced medium was used in the same manner as in Example 11 by using an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 780 nm near infrared semiconductor laser head and an EFM encoder manufactured by KENWOOD, and a linear velocity of 2.8 m / s and a laser power of 8 mW. Recorded in. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

[Example 14] An optical recording medium was prepared in the same manner as in Example 1 except that the azo compound (N) represented by the formula (1) and [Table 1] was used. The produced medium is equipped with a 680 nm red laser head in the same manner as in Example 1, and is an optical disk evaluation device DDU- manufactured by Pulstec Industrial Co., Ltd.
Recording was carried out at a linear velocity of 5.6 m / s and a laser power of 10 mW using an EFM encoder manufactured by 1000 and KENWOOD. After recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown.

Example 15 On the dye layer formed of the azo compound (J) in Example 1, 0.8 g of the phthalocyanine dye represented by [Chemical Formula 7] was dissolved in 40 ml of dimethylcyclohexane (Tokyo Kasei). A dye film was formed under the same conditions by a spin coating method using the solution to prepare an optical recording medium composed of two recording layers. The produced medium was used in the same manner as in Example 11 by using an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 780 nm near infrared semiconductor laser head and an EFM encoder manufactured by KENWOOD, and a linear velocity of 2.8 m / s and a laser power of 8 mW. Recorded in. After recording, after recording, the same measurement as in Example 1 was performed, and as a result, good recording characteristics were shown. Furthermore, when a signal was reproduced using an evaluation device equipped with a 680 nm red semiconductor laser head, the reflectance was 30%.
Showed good recording characteristics.

Example 16 An optical recording medium was prepared in the same manner as in Example 1 except that only the azo compound (G) was used and the light absorbing compound was not mixed. The produced medium was mounted with a 680 nm red laser head in the same manner as in Example 1, and an optical disk evaluation device DDU-10 manufactured by Pulstec Industrial Co., Ltd.
00 and KENWOOD EFM encoder were used for recording at a linear velocity of 2.8 m / s and a laser power of 10 mW. After recording, the same measurement as in Example 1 was performed,
It showed good recording characteristics.

Comparative Example 1 The dye used in Example 1 was the pentamethine cyanine dye NK2929 (1, 3, 3, 3).
1 ', 3', 3'-hexamethyl-2,2 '-(4
An optical recording medium was prepared in the same manner except that 5,4 ′, 5′-dibenzo) indodicarbocyanine perchlorate) (manufactured by Japan Photosensitive Dye Research Institute) was used. An optical disk evaluation device D manufactured by Pulstec Industrial Co., in which the manufactured medium was mounted with a 680 nm red semiconductor laser head as in Example 1
Linear velocity of 5.6 m / s, laser power of 10 using DU-1000 and EFM encoder manufactured by KENWOOD
Recorded in mW. After recording, the same measurement as in Example 1 was performed.

Comparative Example 2 The dye used in Example 1 was the pentamethinecyanine dye NK2627 (3,3′-diethyl-2,2 ′-(6,7,6 ′, 7′-dibenzo) thiadicarbocyanine aio. An optical recording medium was prepared in the same manner except that Dyed) (manufactured by Japan Photosensitive Dye Research Institute) was used. The produced medium was recorded at a linear velocity of 5.6 m / s and a laser power of 10 mW by using an optical disk evaluation device DDU-1000 manufactured by Pulstec Industrial Co., Ltd. equipped with a 680 nm red semiconductor laser head and an EFM encoder manufactured by KENWOOD as in Example 1. did. After recording, the signal was reproduced using the same evaluation apparatus, and as a result, the reflectance was low at 8% and the waveform was distorted. In addition, the same measurement as in Example 1 was performed.

Comparative Example 3 The dye used in Example 1 was pentamethinecyanine dye NK1456 (1,1′-diethyl-2,2′-quinodicarbocyanine iodide).
An optical recording medium was prepared in the same manner except that [manufactured by Japan Photosensitive Dye Research Institute] was used. As in Example 11, the manufactured medium was equipped with a 780 nm near-infrared semiconductor laser head, and an optical disk evaluation device DDU-10 manufactured by Pulstec Industrial Co., Ltd.
00 and KENWOOD EFM encoder were used for recording at a linear velocity of 1.4 m / s and a laser power of 7 mW. After recording, the same measurement as in Example 1 was performed.

[Table 2] shows the measurement results of the reproduction reflectance and the reproduction reflectance / error ratio in a commercially available CD player having a reproduction wavelength of 780 nm when the above 635 nm red semiconductor laser is used.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

INDUSTRIAL APPLICABILITY According to the present invention, by using an azo compound having an absorption maximum at 450 to 630 nm in the recording layer, it is possible to record and reproduce with a conventionally used near-infrared laser of 780 nm, and in recent years. It is possible to provide a compatible optical recording medium capable of recording / reproducing even with a red laser having a recording / reproducing wavelength of 635 nm or 680 nm which is shifting.

[Brief description of drawings]

FIG. 1 is a cross-sectional structure diagram of an optical recording medium.

[Explanation of symbols]

 1 substrate 2 recording layer 3 reflective layer 4 protective layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Sumio Hirose 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemicals, Inc. (72) Denmi Misawa 1190 Kasama-cho, Sakae-ku, Yokohama, Kanagawa Mitsui Toatsu Within Chemicals Co., Ltd. (72) Inventor Keisuke Soma, 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemicals, Inc.

Claims (6)

[Claims] 1. An optical recording medium having a recording layer, a reflective layer and a protective layer on a substrate, wherein the recording layer has an absorption maximum at a wavelength of 450 to 630 nm represented by the formula (1) [Chemical formula 1]. An optical recording medium containing. Embedded image [Wherein R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ each independently represent a hydrogen atom, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted alkyl group, an alkoxy group, or an allyl group. However, two or three of them are cyano groups, and R ₁ is not a nitro group. R ₆ , R ₇ , R ₈ , R ₉ ,
R ₁₀ and R ₁₁ are each independently a hydrogen atom, a halogen atom,
Hydroxy group, carboxyl group, sulfone group, substituted or unsubstituted alkyl group, alkoxy group, allyl group, acyl group, alkylcarboxyl group, aralkyl group, alkylcarbonylamino group, alkylsulfonamino group, alkylamino group, sulfonamide group Represents an amino group, an alkylcarbonyl group, an alkylsulfone group, and a phenyl group, and R ₇ and R ₁₀ , R ₉ and R _11, and R ₁₀ and R ₁₁ may form a ring via a linking group. ] 2. The optical recording medium according to claim 1, wherein the recording layer contains a compound represented by the formula (1) and a light absorbing compound having an absorption maximum at a wavelength of 650 to 900 nm. 3. The optical recording medium according to claim 2, wherein the weight ratio of the light absorbing compound having an absorption maximum at a wavelength of 650 to 900 nm is 0.1 to 50%. 4. The reflectance measured from the substrate side with respect to light selected from a red laser having a wavelength of 620 to 690 nm is 2.
The optical recording medium according to any one of claims 1 to 3, which is 0% or more and is at least reproducible by a red laser having a wavelength of 620 to 690 nm. 5. The reflectance measured from the substrate side with respect to light selected from a red laser having a wavelength of 620 to 690 nm is 2.
The optical recording medium according to any one of claims 1 to 3, which is 0% or more and can be recorded and / or reproduced by a red laser having a wavelength of 620 to 690 nm. 6. The reflectance measured from the substrate side with respect to the light selected from the near infrared laser having a wavelength of 770 to 830 nm is 65% or more, and recording and / or recording is performed with the near infrared laser selected from 770 to 830 nm. It is reproducible.
5. The optical recording medium according to any one of 5 to 5.