JP2005193413A - Optical recording material and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording material and an optical recording medium which can achieve all at a high level the recording/reproducing characteristics, light resistance and film forming properties of a recording layer with a good balance. <P>SOLUTION: In the optical recording medium 1 capable of recording information by the radiation of light, a recording layer 3 containing a chelate compound comprising an azo compound and a metal expressed by formula (1) and formula (2) is provided on a substrate 2 (wherein, A and B express atomic groups constituting an aromatic ring; X<SP>1</SP>expresses a residue after removing two activated hydrogen atoms from a functional group having two or more activated hydrogen atoms; X<SP>2</SP>expresses a residue after removing one activated hydrogen atom from a functional group having one or more activated hydrogen atoms; and Y<SP>1</SP>expresses a substituent). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording medium for recording information by light irradiation and an optical recording material used therefor.

  An optical recording medium generally records information by irradiating a recording layer with a laser and changing the shape, magnetic domain, phase change, etc. of the recording layer. As such an optical recording medium, there is a write-once type optical recording medium having a recording layer containing an organic dye such as an azo dye (see, for example, Patent Documents 1 and 2), a CD-R (write-once compact disc), Widely used as a DVD-R (recordable digital video disk).

  In recent years, there has been a demand for higher density in optical recording media, and in order to meet such demands, the wavelength of recording / reproducing light has been shortened. For example, the wavelength of the current recording / reproducing light of CD-R is 780 nm, but in the next generation CD-R and DVD-R, the wavelength is shortened to 635-680 nm. In such an optical recording medium with a short wavelength, various characteristics such as light resistance and recording sensitivity with respect to the recording / reproducing wavelength required for the dye used are almost the same as those for the current dye. In addition, since the recording layer containing an organic dye is usually formed by a coating method, the organic dye is desirably soluble in the solvent of the coating solution. However, when the organic dyes described in Patent Documents 1 and 2 are used, it is difficult to satisfy all of the above characteristics in a balanced manner.

Therefore, the present applicant has developed an optical recording medium in which a chelating compound having an azo compound substituted with a functional group having active hydrogen as a ligand is contained in the recording layer, and disclosed in Patent Documents 3 and 4, for example.
JP-A-8-108623 JP-A-8-156408 Japanese Patent Laid-Open No. 2000-190641 JP 2000-190642 A

  The chelate compounds described in Patent Documents 3 and 4 are excellent in light resistance and exhibit solubility in a solvent used in a coating solution, and an optical recording medium using the chelate compound is excellent in a specific wavelength. Recording / reproducing characteristics. However, even in this case, there is room for further improvement of various characteristics.

  For example, at the same time as the above-described increase in density, it is desired to increase the recording speed of information on an optical recording medium, and the optical recording medium is required to have higher sensitivity and high speed response. In addition, since high-power laser light is used for speeding up, light resistance to the laser light and the ability to form accurate recording pits even under high temperature conditions by laser light irradiation are required.

  Further, in the case of the chelate compounds described in Patent Documents 3 and 4, the solubility is not necessarily sufficient depending on the type of functional group having active hydrogen. From the viewpoint of improving the film formability of the recording layer and more reliably preventing bleeding out of the chelate compound in the recording layer, it is desirable to further increase the solubility of the chelate compound.

  The present invention has been made in view of such circumstances, and an optical recording material capable of achieving all of recording / reproduction characteristics, light resistance, and film-forming properties of a recording layer at a high level in a balanced manner, and its optical An object of the present invention is to provide an optical recording medium using a recording material.

  As a result of intensive studies to achieve the above object, the present inventors have found that an organic dye containing a chelate compound of an azo compound having a specific structure and a metal exhibits high solubility in a recording layer coating liquid, and organic It has been found that recording / reproducing characteristics and light resistance of an optical recording medium are improved by incorporating a dye in the recording layer, and the present invention has been completed.

  That is, the optical recording material of the present invention is an optical recording material used for an optical recording medium capable of recording information by light irradiation, and an azo compound represented by the following general formula (1) or (2): It contains a chelate compound with a metal.

  The optical recording medium of the present invention is an optical recording medium capable of recording information by light irradiation, and comprises a chelate compound of an azo compound and a metal represented by the following general formula (1) or (2). It is characterized by comprising a recording layer.

[In the formulas (1) and (2), A and B may be the same or different and each represents an atomic group constituting an aromatic ring, and X ¹ is a functional group having two or more active hydrogen atoms. Represents a residue obtained by removing two active hydrogen atoms, X ² represents a residue obtained by removing one active hydrogen atom from a functional group having one or more active hydrogen atoms, and Y ¹ represents a substituent. In the formula (2), two X ¹ and two Y ¹ may be the same or different. ]
In the chelate compound according to the present invention, the linking group —X ¹ H—Y ¹ when the azo compound coordinates with the metal is a site having an active hydrogen atom as shown in the general formula (1) or (2) -X ¹ H- is arranged on the organic dye matrix side, and a monovalent substituent Y ¹ is arranged on the terminal side of the linking group. Here, the organic dye matrix means a structural unit exhibiting characteristics as an azo dye, and more specifically, a part obtained by removing the linking group from the general formula (1) or (2). By using such a chelate compound having a linking group, the solubility in the recording layer coating liquid can be improved while maintaining the light resistance and recording / reproducing characteristics at a high level. Therefore, by including such a chelate compound in the recording layer, even when recording / reproducing information by recording / reproducing light with a short wavelength, the film-forming property, light resistance and recording / reproducing characteristics of the recording layer are improved. An optical recording medium achieved at a high level and in a well-balanced manner can be realized.

In the present invention, X ¹ in the general formula (1) or (2) is preferably a residue obtained by removing two active hydrogen atoms from one selected from an amino group, an amide group, and a sulfonamide group. .

Further, it is preferable that Y ¹ in the general formula (1) or (2) is one selected from an alkyl group, a sulfonic group and an acyl group.

  Further, the azo compound of the chelate compound preferably has a structure represented by the following general formula (3) or (4).

[In Formulas (3) and (4), X ¹ represents a residue obtained by removing two active hydrogen atoms from a functional group having two or more active hydrogen atoms, and X ² represents one or more active hydrogen atoms. Represents a residue obtained by removing one active hydrogen atom from a functional group having R ¹ , Y ¹ represents a substituent, R ¹ and R ² may be the same or different, and each represents an alkyl group, an aryl group, an acyl group Group, alkoxy group, alkenyl group, halogen atom, hydroxy group, carboxyl group, carboxylic acid ester group, sulfone group, sulfonic acid ester group, sulfamoyl group, sulfonamido group, carbamoyl group, amide group, amino group and nitro group M and n may be the same or different, each represents an integer of 0 to 4, and two or more R ¹ or R ² are bonded to adjacent carbon atoms of the benzene ring. When they are combined, R ¹ or R ² may be linked to form a ring, and two X ¹ and two Y ¹ in formula (9) may be the same or different. Good. ]
The metal of the chelate compound is preferably cobalt or nickel.

  The recording layer of the optical recording material of the present invention and the optical recording medium of the present invention preferably further contains a cyanine dye. The chelate compound according to the present invention has an excellent quencher function, and particularly when used in combination with a cyanine dye, regeneration degradation due to oxidative deterioration of the dye can be effectively suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the optical recording material and optical recording medium which can achieve recording / reproduction characteristics, light resistance, and the film-forming property of a recording layer with a high level with sufficient balance are provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as the case may be.

(Optical recording material)
The optical recording material of the present invention contains a chelate compound of a dye and a metal represented by the following general formula (1) or (2).

  In the general formulas (1) and (2) indicating an azo compound, A and B may be the same or different and each represents an atomic group constituting an aromatic ring. That is, the atomic groups A and B each form an aromatic ring together with two carbon atoms involved in the double bond. Specific examples of the aromatic ring include a benzene ring, naphthalene ring, pyridine ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, quinoline ring, imidazole ring, pyrazine ring, pyrrole ring, and indolenine ring. Benzoindolenine ring and the like, among which benzene ring is preferable.

Aromatic ^above, -X ¹ -Y ^1, it may have another substituent of ^-X 2 -Y ² or ^-X 1 -H. Such substituents include alkyl groups, aryl groups, aralkyl groups, acyl groups, alkoxy groups, alkenyl groups, halogen atoms, hydroxy groups, carboxyl groups, carboxylic acid ester groups, sulfone groups, sulfonic acid ester groups, sulfamoyl groups, sulfones. Examples include an amide group, a carbamoyl group, an amino group, an amide group, an alkylthio group, an alkylazomethine group, and a nitro group. When two or more R ¹ or R ² are bonded to adjacent carbon atoms of the aromatic ring, the substituents may be linked to form a ring.

  Of the substituents on the aromatic ring, the alkyl group is preferably an alkyl group having 1 to 12 carbon atoms. The alkyl group may be linear or branched and may be a combination of two or more thereof. In addition, a substituent such as a halogen atom or an alkoxy group may be bonded to the alkyl group.

  Examples of the aryl group include a phenyl group and a tolyl group. The total number of carbon atoms in the aryl group is preferably 6-10. The aryl group may be substituted or unsubstituted.

  Examples of the acyl group include an acetyl group, a propionyl group, and a butyryl group. The total carbon number of the acyl group is preferably 2-5.

  Examples of the aralkyl group include a benzyl group, a hydroxybenzyl group, and a methylbenzyl group. The total number of carbon atoms in the aralkyl group is preferably 7-10.

  As an alkoxy group, a C1-C4 thing is preferable and a methoxy group, an ethoxy group, a propoxy group, a pentafluoropropoxy group etc. are mentioned.

  The alkenyl group may be linear or branched, and specific examples include a vinyl group, an allyl group, a propenyl group, a butenyl group, and a pentenyl group. Those having a total carbon number of 2 to 10 are preferred.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

  The carboxylic acid ester group preferably has 2 to 10 carbon atoms in total, and examples thereof include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, and an acetoxycarbonyl group.

The sulfone group preferably has 1 to 10 carbon atoms in total, and examples thereof include a methylsulfonyl group, a benzenesulfonyl group, an ethylsulfonyl group, and an n-propylsulfonyl group.
As the sulfonic acid ester group, those having 1 to 10 carbon atoms are preferable, and examples thereof include methoxysulfonyl, ethoxysulfonyl, propoxysulfonyl, butoxysulfonyl and the like.

  The sulfamoyl group may have a substituent and is preferably one having a total carbon number of 0 to 10, and includes a sulfamoyl group, a methylsulfamoyl group, an ethylsulfamoyl group, an n-propylsulfamoyl group, an iso -Propyl sulfamoyl group etc. are mentioned.

  As the sulfonamide group, those having 1 to 10 carbon atoms are preferable, and examples thereof include a methylsulfonamide group, an ethylsulfonamide group, and an n-propylsulfonamide group.

  The carbamoyl group may have a substituent and is preferably a group having 1 to 10 carbon atoms in total, such as carbamoyl group, methylcarbamoyl group, ethylcarbamoyl group, n-propylcarbamoyl group, iso-propylcarbamoyl group, and the like. Can be mentioned.

  As the amino group, those having a substituent are preferable, and as the substituted amino group, a dialkylamino group is particularly preferable. In this case, the alkyl part of the dialkylamino group preferably has 1 to 12 carbon atoms, and may be linear or branched.

  The amide group preferably has 2 to 10 carbon atoms in total, and examples thereof include an acetamide group, a propionylamide group, a butyrylamide group, and a benzamide group.

  The alkylthio group preferably has 1 to 4 carbon atoms in total, and examples thereof include a methylthio group, an ethylthio group, an n-propylthio group, and an iso-propylthio group.

  As the alkylazomethine group, those having 2 to 5 carbon atoms are preferable, and examples thereof include a methylazomethine group, an ethylazomethine group, and an n-propylazomethine group.

X ¹ represents a residue obtained by removing two active hydrogen atoms from a functional group having two or more active hydrogen atoms. As the functional group having two or more active hydrogen atoms, an amino group (—NH ₂ ), an amide group (—CONH ₂ ) and a sulfonamide group (—SO ₂ NH ₂ ) are preferable, and an amino group is particularly preferable. Accordingly, X ¹ is preferably —NH—, —CONH—, or —SO ₂ NH—, and particularly preferably —NH—. In addition, two X ¹ and two Y ¹ in Formula (2) may be the same or different.

X ² represents a residue obtained by removing one active hydrogen atom from a functional group having one or more active hydrogen atoms. Examples of the functional group having one or more active hydrogen atoms include a hydroxyl group (—OH), a thiol group (—SH), an amino group (—NH ₂ ), a carboxy group (—COOH), an amide group (—CONH ₂ ), and a sulfone. Amide groups (—SO ₂ NH ₂ ) and sulfo groups (—SO ₃ H) are preferred, and hydroxyl groups are particularly preferred. Accordingly, X ² is preferably —O—, —S—, —NH—, —COO—, —CONH—, —SO ₂ NH— or —SO ₃ —, and particularly preferably —O—.

Y ¹ represents a substituent bonded to X ¹ . Specific examples of Y ¹ include alkyl groups, aryl groups, acyl groups, alkoxy groups, halogen groups, hydroxy groups, carboxyl groups, carboxylic acid ester groups, sulfone groups, sulfamoyl groups, sulfonamido groups, carbamoyl groups, amide groups, Examples thereof include an amino group, an alkenyl group, a cyano group, a nitro group, a mercapto group, a thiocyano group, an alkylthio group, an alkylazomethine group, and an aralkyl group. Among these, an alkyl group, a sulfone group (—SO ₂ —R; R represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group), an acyl group (—CO—R; R represents a substituted or unsubstituted group) Represents a substituted alkyl group or a substituted or unsubstituted aryl group). When R of the sulfone group and the acyl group is an alkyl group, the alkyl group preferably has 1 to 6 carbon atoms.

  Among the azo compounds having the above configuration, an azo compound having a structure represented by the following general formula (3) or (4) is preferable.

Formula (3), (4) ^X 1, ^{X 2} and ^{Y 1} each formula in (1), the same meaning as ^X 1, ^{X 2} and ^{Y 1} in (2). R ¹ and R ² may be the same or different, and are each an alkyl group, aryl group, acyl group, alkoxy group, alkenyl group, halogen atom, hydroxy group, carboxyl group, carboxylic ester group, sulfone group, Represents a monovalent group selected from a sulfonate group, a sulfamoyl group, a sulfonamido group, a carbamoyl group, an amide group, an amino group and a nitro group, and m and n may be the same or different, Represents an integer. When R ¹ or R ² of two or more adjacent carbon atoms of the benzene ring is bonded, R ¹ s or R ² together may form a ring, 2 in the formula (9) The X ¹ and the two Y ¹ may be the same or different.

  Preferable examples of the azo compound according to the present invention include compounds represented by the following formulas (5) to (37).

  In addition, as the metal (central metal) of the chelate compound, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony , Tungsten, rhenium, osmium, iridium, platinum, gold and the like, among which cobalt and nickel are preferable.

  In the chelate compound according to the present invention, a coordinate bond between a tridentate ligand in which two active hydrogen atoms are eliminated from the azo compound represented by the general formula (1) or (2) and a metal is formed. The For example, when the metal is cobalt (Co), as shown in the following formula (38) or (39), two tridentate ligands coordinate with one cobalt atom to form a chelate compound.

Z ⁺ in the general formulas (38) and (39) represents a counter cation. As the counter cation, alkali metal ions such as Na ⁺ , Li ⁺ and K ⁺ , ammonium ions, and the like are preferably used. Further, salt formation may be performed using a light-absorbing dye having a positive charge described later as a counter cation.

  The method for synthesizing the chelate compound according to the present invention is not particularly limited, and can be synthesized according to a conventional method (see, for example, Furukawa, Anal. Chem. Acta., 140, 289 (1982)).

  When the chelate compound according to the present invention is contained in the recording layer of the optical recording medium, the chelate compound may be used alone as a dye, or another light absorbing dye may be used in combination. When the chelate compound according to the present invention is used in combination with other dyes, the excellent quencher function of the chelate compound according to the present invention can further improve various characteristics such as light resistance and electric characteristics of the disc. . Examples of the dye used in combination include a cyanine dye, a hydrazine metal complex, a styryl dye, a porphyrin dye, a rhodamine dye, a triphenylmethane dye, a formazan metal complex, an azo dye other than the above, and a cyanine dye is preferable.

Among the dyes used in combination, a dye having a positive charge is used as the counter cation Z ⁺ in the general formula (38) or (39), and as a salt-forming dye between the chelate compound and a dye having a positive charge. Also good. Examples of positively charged dyes include cyanine dyes such as trimethine cyanine dyes, rhodamine dyes, and triphenylmethane dyes. Among them, cyanine dyes are preferable, and trimethine cyanine dyes are particularly preferable.

  The trimethine cyanine dye preferably used in the present invention is represented by the following general formula (40).

In the general formula (40), Q ¹ and Q ² may be the same or different and each represents an atomic group for forming a 5-membered nitrogen-containing heterocyclic ring which may have a condensed ring. . Examples of such a heterocyclic ring include an indolenine ring, a benzoindolenine ring, an oxazoline ring, a thiazoline ring, a selenazoline ring, and an imidazoline ring, and among them, an indolenine ring and a benzoindolenine ring are preferable. Further, these nitrogen-containing heterocycles may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an alkoxy group, an aryl group, an acyl group, an amino group, and a nitro group.

R ³ and R ⁴ each represents an aliphatic hydrocarbon group, preferably an alkyl group. The alkyl group may have a substituent, and the carbon number is preferably 1 to 5. Examples of the substituent include a halogen atom, an alkyl group, and an ether group.

R ⁵ represents a hydrogen atom, a monovalent substituent such as a halogen atom or an alkyl group.

  Among the trimethine cyanine dyes represented by the general formula (40), compounds represented by the following formulas (41) to (74) are particularly preferable.

  The compounding ratio of the chelate compound according to the present invention and the other dye is not particularly limited, but the chelate compound: other dye = 5: 1 to 1: 3 in a molar ratio including the case of the salt-forming dye. Is preferred.

(Optical recording medium)
FIG. 1 is a partial sectional view showing a preferred embodiment of an optical recording disk according to the optical recording medium of the present invention. An optical recording disk 1 shown in FIG. 1 is a write-once optical recording compact disk corresponding to the CD standard, and is capable of recording / reproducing with light having a short wavelength of 630 to 685 nm.

  The optical recording disk 1 has a laminated structure in which a recording layer 3, a reflective layer 4, and a protective plate are provided in close contact with each other on a substrate 2.

  The substrate 2 has a disk shape with a diameter of about 64 to 200 mm and a thickness of about 1.2 mm. In order to enable recording and reproduction from the back side (the side opposite to the recording layer 3) of the substrate 2, the substrate 2 is preferably substantially transparent to the recording light and the reproduction light, more specifically. The transmittance of the substrate 2 with respect to recording light and reproducing light is preferably 88% or more. As the material of the substrate 2, a resin or glass that satisfies the above-described conditions regarding the transmittance is preferable, and among them, a thermoplastic resin such as a polycarbonate resin, an acrylic resin, an amorphous polyethylene, TPX, or a polystyrene resin is particularly preferable.

  Further, a tracking groove 23 is formed on the surface of the substrate 2 where the recording layer 3 is formed, as shown in FIG. The groove 23 is preferably a spiral continuous groove, and has a depth of 0.1 to 0.25 μm, a width of 0.35 to 0.60 μm, and a groove pitch of 1.5 to 1.7 μm. Is preferred. By configuring the groove in this way, a good tracking signal can be obtained without reducing the reflection level of the groove. The groove 23 can be formed at the same time when the substrate 2 is formed by injection molding or the like using the above resin. However, after the substrate 2 is manufactured, a resin layer having the groove 23 is formed by the 2P method or the like, and the substrate 2 and the resin are formed. It is good also as a composite substrate with a layer.

  The recording layer 3 is formed by including the chelate compound according to the present invention, and preferably further contains another dye.

  The recording layer 3 can be formed by applying a coating solution containing the chelate compound according to the present invention on the substrate 2 and drying the coating film as necessary. Specific examples of the solvent for the coating liquid include alcohol solvents (including alkoxy alcohols such as keto alcohols and ethylene glycol monoalkyl ethers), aliphatic hydrocarbon solvents, ketone solvents, and ester solvents. , Ether solvents, aromatic solvents, alkyl halide solvents and the like. Among them, alcohol solvents and aliphatic hydrocarbon solvents are preferable.

  As the alcohol solvent, an alkoxy alcohol system, a keto alcohol system, or the like is preferable. In the alkoxy alcohol solvent, the alkoxy moiety preferably has 1 to 4 carbon atoms, the alcohol moiety preferably has 1 to 5 carbon atoms, more preferably 2 to 5 carbon atoms, and the total number of carbon atoms. It is preferable that it is 3-7. Specifically, ethylene glycol monoalkyl ether (cellosolve) such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (also referred to as ethyl cellosolve, ethoxyethanol), butyl cellosolve, 2-isopropoxy-1-ethanol, etc. And 1-methoxy-2-propanol, 1-methoxy-2-butanol, 3-methoxy-1-butanol, 4-methoxy-1-butanol, 1-ethoxy-2-propanol and the like. Examples of keto alcohols include diacetone alcohol. Furthermore, fluorinated alcohols such as 2,2,3,3-tetrafluoropropanol can also be used.

  As the aliphatic hydrocarbon solvent, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, dimethylcyclohexane, n-octane, iso-propylcyclohexane, t-butylcyclohexane and the like are preferable. Cyclohexane and the like are preferable.

  Moreover, cyclohexanone etc. are mentioned as a ketone type | system | group.

  In the present invention, an alkoxy alcohol system such as an ethylene glycol monoalkyl ether system is particularly preferable, and ethylene glycol monoethyl ether, 1-methoxy-2-propanol, 1-methoxy-2-butanol and the like are particularly preferable. A solvent may be used individually by 1 type, or 2 or more types of mixed solvents may be sufficient as it. For example, a mixed solvent of ethylene glycol monoethyl ether and 1-methoxy-2-butanol is preferably used.

  In addition to the chelate compound and other pigments according to the present invention, the coating liquid may appropriately contain a binder, a dispersant, a stabilizer, and the like. The content of the chelate compound in the coating solution is preferably 0.05 to 10 wt%.

  As a coating method of the coating liquid, a spin coating method, a gravure coating method, a spray coating method, a dip coating method, or the like can be applied, and among these, the spin coating method is preferable.

  The thickness of the recording layer 3 thus formed is preferably 50 to 300 nm in terms of a dry film thickness. Outside this range, the reflectivity decreases and it becomes difficult to perform reproduction in accordance with the CD standard. Further, when the thickness of the recording layer 3 located above the groove 23 is 100 nm or more, particularly 130 to 300 nm or more, the degree of modulation becomes extremely large.

  Further, the extinction coefficient (imaginary part k of the complex refractive index) of the recording layer 3 with respect to the recording light and the reproducing light is preferably 0 to 0.20. When the extinction coefficient exceeds 0.20, sufficient reflectance tends not to be obtained. The refractive index of the recording layer 3 (real part n of the complex refractive index) is preferably 1.8 or more. When the refractive index is less than 1.8, the degree of signal modulation tends to be small. The upper limit of the refractive index is not particularly limited, but is usually about 2.6 for the convenience of organic dye synthesis.

  The extinction coefficient and refractive index of the recording layer 3 can be obtained according to the following procedure. First, a measurement sample is prepared by providing a recording layer on a predetermined transparent substrate at about 40 to 100 nm, and then the reflectance of the measurement sample through the substrate or the reflectance from the recording layer side is measured. Desired. In this case, the reflectance is measured by specular reflection (about 5 °) using the wavelength of the recording / reproducing light. Further, the transmittance of the sample is measured. From these measured values, the extinction coefficient and the refractive index can be calculated according to the method described in, for example, Kyoritsu Zensho “Optics”, Kozo Ishiguro, pages 168 to 178.

  On the recording layer 3, the reflective layer 4 is provided in close contact with the recording layer 3. The reflective layer 4 can be formed by performing vapor deposition, sputtering, or the like using a highly reflective metal or alloy. Examples of such metals and alloys include gold (Au), copper (Cu), aluminum (Al), silver (Ag), and AgCu. The thickness of the reflective layer 4 thus formed is preferably 50 to 120 nm.

  On the reflective layer 4, a protective layer 5 is provided in close contact with the reflective layer 4. The protective layer 5 may be a layer or a sheet. For example, the protective layer 5 is formed by applying a coating liquid containing a material such as an ultraviolet curable resin on the reflective layer 4 and drying the coating film as necessary. Is possible. In such coating, spin coating, gravure coating, spray coating, dip coating, or the like can be applied. The thickness of the protective layer 5 thus formed is preferably 0.5 to 100 μm.

  When recording or additional recording is performed on the optical recording disk 1 having the above-described configuration, recording light having a predetermined wavelength is irradiated in a pulsed manner from the back surface of the substrate 2 to change the light reflectivity of the irradiation unit. At this time, according to the optical recording disk 1 provided with the recording layer 3 containing the chelate compound according to the present invention, even when information is recorded / reproduced by a short wavelength recording / reproducing light, The film formability, light resistance, and recording / reproducing characteristics can be achieved at a high level in a well-balanced manner.

  In the above embodiment, an optical recording disk having one recording layer 3 has been described. However, a plurality of recording layers may be provided and different organic dyes may be contained in each layer. Thereby, information can be recorded / reproduced by a plurality of recording / reproducing lights having different wavelengths.

  FIG. 2 is a partial sectional view showing a preferred embodiment of an optical recording disk according to the optical recording medium of the present invention. An optical recording disk 10 shown in FIG. 2 is a write-once digital video disk corresponding to the DVD standard, and performs recording / reproduction with light having a short wavelength of 635 nm.

  The optical recording disk 10 is obtained by bonding two optical recording disks having the same structure as the optical recording disk 1 shown in FIG. 1 with an adhesive so that their protective layers face each other. That is, the optical recording disk 10 is viewed from one side, the substrate 12, the recording layers 13. The reflective layer 14, the protective layer 15, the adhesive layer 50, the protective layer 25, the reflective layer 24, the recording layer 23, and the substrate 22 are stacked in this order.

  As a material of the adhesive layer 50, a thermosetting resin or the like is preferably used. The thickness of the adhesive layer 50 is about 10 to 200 μm.

  The configurations of the substrates 12 and 22, the recording layers 13 and 23, the reflective layers 14 and 24, and the protective layers 15 and 25 are the same as those of the optical recording disk 1 shown in FIG. In this case, the thickness of each of the substrates 12 and 22 is about 0.6 μm. Grooves 123 and 223 are formed on the recording layer 13 formation surface of the substrate 12 and the recording layer 24 formation surface of the substrate 23, respectively. The grooves 123 and 223 have a depth of 60 to 200 nm and a width of 0. .2 to 0.5 .mu.m and the groove pitch is 0.6 to 1.0 .mu.m. The thickness of each of the recording layers 13 and 23 is 50 to 300 nm, and the complex refractive index for light of 635 nm is n = 1.8 to 2.6, and k = 0.02 to 0.20.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

(Synthesis Example 1)
A chelate compound of an azo compound represented by the above formula (20) and cobalt was synthesized according to the following procedure.

  First, 50.0 g (240 mmol) of N, N-dimethyl-1,3-phenylenediamine hydrochloride was dissolved in 500 mL of dichloromethane under an argon stream, and 100.0 g of trifluoromethanesulfonic acid anhydride was stirred at 5 ° C. or lower. (350 mmol) was added dropwise. The reaction product was purified by washing 3 times with distilled water and 4 times with hexane, and N- (3-dimethylamino-phenyl) -C, C, C-trifluoro-methane represented by the following formula (76). 34.1 g (130 mmol) of sulfonamide was obtained.

  On the other hand, 1.54 g (10 mmol) of 2-amino-4-nitrophenol was dissolved in 2 ml of water and 20 ml of ethanol, and stirred at 0 to 5 ° C., 0.69 g (10 mmol) of sodium nitrite dissolved in 15 ml of water. Was gradually added to diazotize to obtain a diazonium salt.

Next, N- (3-dimethylamino-phenyl) -C, C, C-trifluoro-methanesulfonamide 2.68 g (10 mmol), sodium acetate 4.1 g (50 mmol), urea 0.6 g (10 mmol) was added to methanol. The solution was dissolved in 100 ml, and the diazonium salt was gradually added to the solution for coupling. After completion of the reaction, suction filtration was performed, and the obtained crystals were vacuum-dried to obtain 4.48 g (9.4 mmol) of Na ⁺ salt of the azo compound (20).

Furthermore, 0.10 g of sodium hydroxide, 10 g of water and 20 g of methanol were added to 0.95 g (2 mmol) of the Na ⁺ salt of the azo compound (20), and reacted at 95 ° C. for 16 hours with 0.25 g (1 mmol) of cobalt acetate. I let you. After completion of the reaction, suction filtration was performed, and the resulting crystals were vacuum dried. Thus, 0.87 g (9.2 mmol) of a chelate compound of the azo compound represented by formula (20) and cobalt (the following formula (77)) was obtained.

In this way, PF ₆ birds cyanine dye represented by the obtained chelate compound of formula (67) ^- and salts, the molar ratio is mixed so that the 40:60, to give the desired dye mixture .

(Synthesis Example 2)
Similar to Synthesis Example 1 except that 34 g (240 mmol) of methyl iodide was used instead of 100.0 g (350 mmol) of trifluoromethanesulfonic anhydride, the azo compound represented by formula (5) and cobalt A chelate compound was synthesized.

(Synthesis Example 3)
In the same manner as in Synthesis Example 1 except that 49.0 g (240 mmol) of iodobenzene was used instead of 100.0 g (350 mmol) of trifluoromethanesulfonic anhydride, the azo compound represented by formula (9) and cobalt The chelate compound was synthesized.

In this way, PF ₆ birds cyanine dye represented by the obtained chelate compound of formula (60) ^- and salts, the molar ratio is mixed so that the 40:60, to give the desired dye mixture .

(Synthesis Example 4)
In the same manner as in Synthesis Example 1 except that 33 g (288 mmol) of methanesulfonic acid chloride was used instead of 100.0 g (350 mmol) of trifluoromethanesulfonic anhydride, the azo compound represented by formula (15) and cobalt The chelate compound was synthesized.

In this way, PF ₆ birds cyanine dye represented by the obtained chelate compound of formula (63) ^- and salts, the molar ratio is mixed so that the 40:60, to give the desired dye mixture .

(Synthesis Example 5)
In the same manner as in Synthesis Example 1 except that 50 g (283 mmol) of p-toluenesulfonic acid chloride was used instead of 100.0 g (350 mmol) of trifluoromethanesulfonic anhydride, the azo compound represented by the formula (25) A chelate compound with cobalt was synthesized.

In this way, PF ₆ birds cyanine dye represented by the obtained chelate compound of formula (65) ^- and salts, the molar ratio is mixed so that the 40:60, to give the desired dye mixture .

(Synthesis Example 6)
Chelate of azo compound represented by formula (31) and cobalt in the same manner as in Synthesis Example 1 except that 40 g (285 mmol) of benzoyl chloride was used instead of 100.0 g (350 mmol) of trifluoromethanesulfonic anhydride. The compound was synthesized.

In this way, PF ₆ birds cyanine dye represented by the obtained chelate compound of formula (71) ^- and salts, the molar ratio is mixed so that the 40:60, to give the desired dye mixture .

(Synthesis Example 7)
In the same manner as in Synthesis Example 2, an azo compound represented by formula (5) was synthesized, and a salt-forming dye composed of the obtained azo compound and a trimethine cyanine dye (42) represented by formula (42) was synthesized. . Furthermore, PF ₆ birds cyanine dye represented by a salt forming dye of the formula (42) ^- and salts, the molar ratio is mixed so that the ratio of 50:50 to obtain the desired dye mixture.

(Synthesis Example 8)
In the same manner as in Synthesis Example 2, an azo compound represented by the formula (5) was synthesized, and a salt-forming dye composed of the obtained azo compound and the trimethine cyanine dye represented by the formula (42) was synthesized. Furthermore, PF ₆ birds cyanine dye represented by a salt forming dye of the formula (63) ^- and salts, the molar ratio is mixed so that the ratio of 50:50 to obtain the desired dye mixture.

(Example 1)
First, a polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm having a pre-groove (depth 0.12 μm, width 0.30 μm, groove pitch 0.74 μm) on one side was prepared. Meanwhile, a recording layer coating solution was prepared by adding the dye mixture obtained in Synthesis Example 1 to 2,2,3,3-tetrafluoropropanol so that the content thereof was 1.0 wt%. The obtained coating solution was applied on the surface of the polycarbonate resin substrate on which the pregroove was formed, and dried to form a recording layer (thickness: 100 nm). Next, an Ag reflection layer (thickness 85 nm) is formed on the recording layer by sputtering, and a transparent protective layer (thickness 5 μm) made of an ultraviolet curing acrylic resin is formed on the Ag reflection layer. A laminated structure was obtained. Two such laminated structures were produced and bonded with an adhesive so that their protective layers were on the inside, and an optical recording disk having the structure shown in FIG. 2 was obtained.

(Example 2)
An optical recording disk was produced in the same manner as in Example 1 except that the chelate compound obtained in Synthesis Example 2 was used instead of the dye mixture obtained in Synthesis Example 1.

(Examples 3 to 8)
In Examples 3 to 8, an optical recording disk was prepared in the same manner as in Example 1 except that the dye mixture obtained in Synthesis Example 3 to 8 was used instead of the dye mixture obtained in Synthesis Example 1. Produced.

(Comparative Example 1)
An optical recording disk was produced in the same manner as in Example 1 except that an azo compound represented by the following formula (78) was used instead of the dye mixture obtained in Synthesis Example 1.

(Comparative Example 2)
Example 1 was used except that an equimolar mixture of the azo compound represented by the above formula (78) and the ClO ₄ salt of trimethine cyanine dye (53) was used instead of the dye mixture obtained in Synthesis Example 1. Similarly, an optical disk was produced.

(Comparative Example 3)
Instead of the dye mixture obtained in Synthesis Example 1, the same procedure as in Example 1 was used except that a salt-forming dye of an azo metal complex represented by the following formula (79) and a trimethine cyanine dye (53) was used. An attempt was made to produce an optical disk. However, the recording layer could not be formed because the solubility of the salt-forming dye was insufficient.

(Comparative Example 4)
In the same manner as in Example 1 except that a dye represented by the following formula (80), which is a salt-forming dye of an azo metal complex and a rhodamine dye, was used instead of the dye mixture obtained in Synthesis Example 1. A recording disk was produced.

(Comparative Example 5)
Similar to Example 1 except that a salt-forming dye of an azo compound represented by the following formula (81) and a cyanine dye represented by formula (49) was used instead of the dye mixture obtained in Synthesis Example 1. Thus, an optical recording disk was produced.

(Evaluation of recording / playback characteristics)
Next, for each of the optical recording disks of Examples 1 to 8 and Comparative Examples 1, 2, 4, and 5, a signal was sent at a linear velocity of 3.5 m / s or 28.0 m / s using a laser beam having a wavelength of 655 nm. Recorded. Next, reproduction was performed at a linear velocity of 3.5 m / s using laser light having a wavelength of 655 nm. The lens hole diameter NA was 0.60. The characteristics at this time were evaluated based on reflectance (R _top ), modulation degree (Mod.), Jitter (Jitter), and optimum recording power (P ₀ ). Table 1 shows the results when recorded at a linear velocity of 3.5 m / s, and Table 2 shows the results when recorded at a linear velocity of 28.0 m / s.

表１、２に示した通り、実施例１〜８の光記録ディスクは、線速３．５ｍ／ｓ及び２８．０ｍ／ｓのいずれの場合においても、良好な記録・再生特性を示し、高速記録に十分適応可能であることがわかった。

As shown in Tables 1 and 2, the optical recording disks of Examples 1 to 8 showed good recording / reproducing characteristics at both linear speeds of 3.5 m / s and 28.0 m / s, and high speed. It was found that it can be adapted to the recording sufficiently.

  In contrast, in the optical recording disks of Comparative Examples 1 and 2, a significant increase in jitter and an increase in optimum recording power were observed at both linear speeds of 3.5 m / s and 28.0 m / s. . Further, the optical recording disk of Comparative Example 4 could not be recorded due to insufficient sensitivity at both linear speeds of 3.0 m / s and 28.0 m / s. Furthermore, the optical recording disk of Comparative Example 5 showed a slightly large value for the optimum recording power at both linear speeds of 3.5 m / s and 28.0 m / s.

(Evaluation of light resistance)
The light resistance of each optical recording disk of Examples 1 to 8 was evaluated. Specifically, the jitter of the disc after 40 hours of irradiation with an 80,000-lux xenon lamp (Xenon Fade Meter manufactured by Shimadzu Corporation) was measured. As a result, no change in jitter was observed in any of the optical recording disks of Examples 1 to 8.

(Reliability evaluation)
Each optical recording disk of Examples 1 to 8 was subjected to a reliability test for 100 hours under the conditions of 80 ° C. and 80% RH. As a result, no deterioration of the characteristics was observed in any of the optical recording disks of Examples 1 to 8.

1 is a partial cross-sectional view showing a preferred embodiment of an optical recording disk according to an optical recording medium of the present invention. 1 is a partial cross-sectional view showing a preferred embodiment of an optical recording disk according to an optical recording medium of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,10 ... Optical recording disk 2, 12, 22 ... Substrate 3, 13, 23 ... Recording layer 4, 14, 24 ... Reflective layer 5, 15, 25 ... Protective layer, 23, 123, 223 ... Groove 50 ... Adhesive layer.

Claims (12)

An optical recording material used for an optical recording medium capable of recording information by light irradiation,
An optical recording medium comprising a chelate compound of an azo compound represented by the following general formula (1) or (2) and a metal.

[In the formulas (1) and (2), A and B may be the same or different and each represents an atomic group constituting an aromatic ring, and X ¹ is a functional group having two or more active hydrogen atoms. Represents a residue obtained by removing two active hydrogen atoms, X ² represents a residue obtained by removing one active hydrogen atom from a functional group having one or more active hydrogen atoms, and Y ¹ represents a substituent. In the formula (2), two X ¹ and two Y ¹ may be the same or different. ] X ¹ in the general formula (1) or (2) is a residue obtained by removing two active hydrogen atoms from one selected from an amino group, an amide group, and a sulfonamide group, Item 4. The optical recording material according to Item 1. The optical recording material according to claim 1, wherein Y ¹ in the general formula (1) or (2) is one selected from an alkyl group, a sulfone group, and an acyl group. The optical recording material according to any one of claims 1 to 3, wherein the azo compound has a structure represented by the following general formula (3) or (4).

[In Formulas (3) and (4), X ¹ represents a residue obtained by removing two active hydrogen atoms from a functional group having two or more active hydrogen atoms, and X ² represents one or more active hydrogen atoms. Represents a residue obtained by removing one active hydrogen atom from a functional group having R ¹ , Y ¹ represents a substituent, R ¹ and R ² may be the same or different, and each represents an alkyl group, an aryl group, an acyl group Group, alkoxy group, alkenyl group, halogen atom, hydroxy group, carboxyl group, carboxylic acid ester group, sulfone group, sulfonic acid ester group, sulfamoyl group, sulfonamido group, carbamoyl group, amide group, amino group and nitro group M and n may be the same or different, each represents an integer of 0 to 4, and two or more R ¹ or R ² are bonded to adjacent carbon atoms of the benzene ring. When they are combined, R ¹ or R ² may be linked to form a ring, and two X ¹ and two Y ¹ in formula (9) may be the same or different. Good. ] The optical recording material according to claim 1, wherein the metal is cobalt or nickel. The optical recording material according to claim 1, further comprising a cyanine dye. An optical recording medium capable of recording information by light irradiation, comprising a recording layer containing a chelate compound of an azo compound represented by the following general formula (1) or (2) and a metal Optical recording medium.

[In the formulas (1) and (2), A and B may be the same or different and each represents an atomic group constituting an aromatic ring, and X ¹ is a functional group having two or more active hydrogen atoms. Represents a residue obtained by removing two active hydrogen atoms, X ² represents a residue obtained by removing one active hydrogen atom from a functional group having one or more active hydrogen atoms, and Y ¹ represents a substituent. In the formula (2), two X ¹ and two Y ¹ may be the same or different. ] X ¹ in the general formula (1) or (2) is a residue obtained by removing two active hydrogen atoms from one selected from an amino group, an amide group, and a sulfonamide group, Item 8. The optical recording medium according to Item 7. 9. The optical recording medium according to claim 7, wherein Y ¹ in the general formula (1) or (2) is one selected from an alkyl group, a sulfone group, and an acyl group. The optical recording medium according to claim 7, wherein the azo compound has a structure represented by the following general formula (3) or (4).

[In Formulas (3) and (4), X ¹ represents a residue obtained by removing two active hydrogen atoms from a functional group having two or more active hydrogen atoms, and X ² represents one or more active hydrogen atoms. Represents a residue obtained by removing one active hydrogen atom from a functional group having R ¹ , Y ¹ represents a substituent, R ¹ and R ² may be the same or different, and each represents an alkyl group, an aryl group, an acyl group Group, alkoxy group, alkenyl group, halogen atom, hydroxy group, carboxyl group, carboxylic acid ester group, sulfone group, sulfonic acid ester group, sulfamoyl group, sulfonamido group, carbamoyl group, amide group, amino group and nitro group M and n may be the same or different, each represents an integer of 0 to 4, and two or more R ¹ or R ² are bonded to adjacent carbon atoms of the benzene ring. When they are combined, R ¹ or R ² may be linked to form a ring, and two X ¹ and two Y ¹ in formula (9) may be the same or different. Good. ] The optical recording medium according to claim 7, wherein the metal is cobalt or nickel. The optical recording medium according to claim 7, wherein the recording layer further contains a cyanine dye.

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