JP2000118145A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical recording medium, having record reproducing characteristics such as a sufficient solubility in a coating solvent, not invading a polycarbonate substrate, and a good jitter, shown under a specified wavelength, and the like, by a method wherein a specified coloring matter is contained in a recording layer, in an optical recording medium. SOLUTION: A heat mode system optical recording medium, containing a xanthene coloring matter shown by a formula and having the wavelength of recording and reproducing light of lower than 680 nm, is constituted in a recording layer. In the formula, A shows as atomic group forming a complicated ring together with bonded two carbon atoms, and Y shows a carbonic acid group or the like. R1, R2, R5, R6, R9 and R10 show hydrogen atom, halogen atom and the like independently and respectively. R3, R4, R7, and R8 show hydrogen atom, halogen atom, alyl group and the like independently and respectively. R1 and R2, R2 and R3, R3 and R4, R4 and R5, R6 and R7, R7 and R8, R8 and R9 as well as R9 and R10 can form a ring respectively by bonding with each other. X shows resistance to anion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a reflective layer, and preferably forming pits by irradiating a laser. In particular, the recording / reproducing wavelength is 600 to
It relates to a 680 nm optical recording medium.

[0002]

2. Description of the Related Art A recording method of an optical recording medium which is currently put into practical use is a heat mode recording method in which an irradiation laser beam is used as a heat source to cause evaporation or decomposition of a recording layer to form optically detectable concave pits. It is.

[0003] On the other hand, as another recording method which has not been put into practical use yet, there are many problems, and a recording layer having various phosphors is irradiated with light to perform physical and chemical changes for recording. A photon mode recording method characterized by detecting the emission of light is proposed in JP-A-2-308439 and JP-A-8-6204. Here, the dye used in the recording layer of the disclosed optical recording medium is rhodamine 6
G, rhodamine B and the like.

Conventionally, as an organic dye-based recording layer of an optical recording medium in a heat mode, a cyanine dye is mentioned as one of them, but light deterioration is remarkable and stability is poor. In addition, azo dyes may be mentioned, but they have high light resistance, but have problems such as low reflectance. Further, Japanese Patent Application Laid-Open No. 10-97732 discloses an optical recording medium in which a specific xanthene dye such as rhodamine B is contained in a recording layer. However, the optical recording medium has a short light absorption wavelength, a reflectance (Rtop) and a modulation degree. There is a problem that can not be balanced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to have excellent recording and reproducing characteristics such as having sufficient solubility in a coating solvent which does not attack the polycarbonate substrate and exhibiting a good jitter at a wavelength of 680 nm or less. It is to provide an optical recording medium. Another object is to provide an optical recording medium having excellent light resistance.

[0006]

This and other objects are achieved by the following (1) to (4). (1) The recording and reproducing light has a wavelength of 680 nm or less, has a recording layer containing a dye on a substrate, has a reflective layer on the recording layer, and forms pits by irradiating light. An optical recording medium for performing recording, wherein the recording layer contains a dye represented by the following formula (I).

[0007]

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[In the formula (I), A represents an atomic group forming a heterocyclic ring together with two carbon atoms to which it is bonded, Y represents a carboxylic acid group, a carboxylic acid ester group, Represents a carbamoyl group, a sulfonic group, a sulfonic ester group or a sulfamoyl group. R ₁ , R ₂ ,
R ₅ , R ₆ , R ₉ and R ₁₀ each independently represent a hydrogen atom, a halogen atom, an amino group, a sulfonamide group, an amide group,
Represents a carbamoyl group, a nitro group, a sulfonic ester group, a carboxylic ester group, a nitrile group, or an alkyl group, an alkoxy group or an alkenyl group having 16 or less carbon atoms. R ₃ , R ₄ , R ₇ and R ₈ each independently represent a hydrogen atom,
Halogen atom, aryl group, heterocyclic group or carbon number 16
Represents the following alkyl groups or alkoxy groups. R ₁ and R _2, R ₂ and R _3, R ₃ and R _4, R ₄ and R _5, R ₆ and R _7, R ₇ and R _8, R ₈ and R _9, R ₉ and R ₁₀ are each It may combine with each other to form a ring. X ^- represents a counter anion. Optical recording medium of the counter anion represented by is an anion of an organic metal complex (1) ^- (2) (I) in the X. (3) The above (1) wherein A in the formula (I) forms a pyridine ring together with the two carbon atoms to which it is bonded.
Or the optical recording medium of (2). (4) The optical recording medium according to any one of (1) to (3), wherein the recording layer further contains a dye of an organometallic complex.

JP-A-10-97732 discloses a heat mode type optical recording medium in which a specific xanthene dye such as rhodamine B is contained in a recording layer.
However, the xanthene dye disclosed herein, unlike the dye represented by the formula (I) of the present invention, does not have a structure in which a heterocyclic group is bonded to the 9-position (center carbon) of the xanthene ring.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The optical recording medium of the present invention is a heat mode system in which recording and reproducing light has a wavelength of 680 nm or less, has a reflective layer on a recording layer, and performs recording by forming small holes called pits by light irradiation. Wherein the recording layer contains a xanthene dye represented by the formula (I).

In the formula (I), A represents an atomic group forming a heterocyclic ring together with two carbon atoms to which it is bonded, and Y represents a carboxylic acid group, a carboxylic ester group, or a carbamoyl group. A sulfonic acid group, a sulfonic acid ester group or a sulfamoyl group. R ₁ , R ₂ , R ₅ ,
R ₆ , R ₉ and R ₁₀ each represent a hydrogen atom, a halogen atom,
Represents an amino group, a sulfonamide group, an amide group, a carbamoyl group, a nitro group, a sulfonic acid ester group, a carboxylic acid ester group, a nitrile group, or an alkyl group, an alkoxy group or an alkenyl group having 16 or less carbon atoms. R ₃ ,
R ₄ , R ₇ and R ₈ each represent a hydrogen atom, a halogen atom,
Represents an aryl group, a heterocyclic group, or an alkyl group or an alkoxy group having 16 or less carbon atoms. Adjacent ones of R _{1 to} R ₁₀ may be bonded to each other to form a ring. X ^- represents a counter anion.

The heterocyclic ring completed by A may be a single ring or a ring having a condensed ring, and is preferably an aromatic nitrogen-containing 6-membered heterocyclic ring, and specific examples include a pyridine ring and a quinoline ring. Can be Among them, a pyridine ring and a quinoline ring are preferable, and a pyridine ring is particularly preferable. The pyridine ring and the quinoline ring are preferably bonded to the 9-position (center carbon) of the xanthene ring in the formula (I) at the 2-, 3-positions.

These heterocycles may have a substituent other than Y and a xanthenyl group. Examples of such a substituent include an alkyl group, a halogenated alkyl group, an aryl group, an alkoxy group and a halogenated alkyl group. Alkoxy group, aryloxy group, alkylthio group, arylthio group, aralkyl group, halogen atom, cyano group, nitro group, ester group, carbamoyl group, acyl group, acylamino group, sulfamoyl group, sulfonamide group, and the like,
These substituents may further have a substituent.

Among these substituents on the heterocyclic ring, preferred substituents are those having 1 to 5 carbon atoms which may have a substituent.
Examples include an alkyl group up to 8, an alkoxy group having 1 to 8 carbon atoms, a nitro group, and a halogen atom.

Y represents a carboxylic acid group, a carboxylic acid ester group, a carbamoyl group, a sulfonic acid group, a sulfonic acid ester group, or a sulfamoyl group. The carboxylic acid ester group preferably has 2 to 4 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, and acetoxy. The carbamoyl group preferably has 1 to 10 carbon atoms and may have a substituent, and examples thereof include carbamoyl, methylcarbamoyl, dimethylcarbamoyl, diethylcarbamoyl, and dipropylcarbamoyl. The sulfonic acid ester group preferably has 1 to 4 carbon atoms, for example, methoxysulfonyl, ethoxysulfonyl, propoxysulfonyl,
Butoxysulfonyl and the like. The sulfamoyl group preferably has 0 to 10 carbon atoms and may have a substituent, for example, sulfamoyl, methylsulfamoyl, ethylsulfamoyl, n-propylsulfamoyl, iso-propylsulfamoyl and the like. Is mentioned. The carboxylic acid group and the sulfonic acid group may form a salt.

As Y, a carboxylic acid group is preferable.

The halogen atom represented by R _{1 to} R ₁₀ includes F, Cl, Br, I and the like.

The alkyl group having 16 or less carbon atoms, preferably _{1 to} 16 carbon atoms represented by R _{1 to} R ₁₀ may be linear or branched, and specifically, methyl, Ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl. It may have a substituent,
Examples of such a substituent include an alkoxy group such as methoxy and ethoxy, an alkoxycarbonyl group, a hydroxy group, a hydroxyoxy (hydroperoxy) group, and a halogen atom. Even when it has a substituent, the carbon number is 1 to 1
6 is preferable.

The alkoxy group represented by R _{1 to} R ₁₀ and having 16 or less carbon atoms, preferably _{1 to} 16 carbon atoms, may have a linear or branched alkyl moiety. Specific examples include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, s-butoxy, t-butoxy, n-pentyloxy, n-hexyloxy and the like. Unsubstituted ones are preferred, but may further have substituents. Also when it has a substituent, it preferably has 1 to 16 carbon atoms.

The amino group represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ , and R ₁₀ preferably has 0 to 6 carbon atoms, and may have a substituent. Methylamino, dimethylamino and the like can be mentioned.

The sulfonamide group represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ , and R ₁₀ is preferably a sulfonamide group having 1 to 6 carbon atoms. Sulfonamide, benzenesulfonamide and the like can be mentioned.

The amide group represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ and R ₁₀ preferably has 1 to 10 carbon atoms.
It may have a substituent, and examples thereof include amide, acetamide, and benzamide.

The carbamoyl group represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ , and R ₁₀ is preferably a group having 1 to 10 carbon atoms, and may have a substituent. Methylcarbamoyl, phenylcarbamoyl and the like can be mentioned.

The sulfonic ester groups represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ and R ₁₀ are preferably those having 1 to 4 carbon atoms, and may have a substituent. Examples include methoxysulfonyl, ethoxysulfonyl, propoxysulfonyl, butoxysulfonyl and the like.

The carboxylic acid ester groups represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ and R ₁₀ are preferably those having 2 to 4 carbon atoms, and may have a substituent. Methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, acetoxy and the like can be mentioned.

The alkenyl group having 16 or less carbon atoms, preferably 2 to 16 carbon atoms, represented by R ₁ , R ₂ , R ₅ , R ₆ , R ₉ , and R ₁₀ may have a substituent. It may be linear or branched, and examples thereof include vinyl, allyl, propenyl, and butenyl.

The aryl group represented by R ₃ , R ₄ , R ₇ and R ₈ may have a single ring or a condensed ring, and examples thereof include phenyl and naphthyl.

The heterocyclic group represented by R ₃ , R ₄ , R ₇ and R ₈ may be a single ring or a fused ring, and is preferably an aromatic nitrogen-containing 6-membered heterocyclic group. And quinolinyl.

These aryl groups and heterocyclic groups may have a substituent. Examples of such a substituent include an alkyl group, a halogenated alkyl group, an alkoxy group, a halogenated alkoxy group, a halogen atom, and a cyano group. Group, nitro group,
Examples thereof include an ester group, a carbamoyl group, an acyl group, an acylamino group, a sulfamoyl group, a sulfonamide group, and the like. These substituents may further have a substituent.

The aryl group and the heterocyclic group including such substituents preferably have 6 to 20 carbon atoms for the aryl group and 5 to 19 carbon atoms for the heterocyclic group.

In such a case, it is preferable that one of R ₃ and R ₄ and one of R ₇ and R ₈ be an aryl group or a heterocyclic group.

R ₁ , R ₂ , R ₅ , R ₆ , R ₉ and R ₁₀ are preferably a hydrogen atom or an alkyl group having 1 to 16 carbon atoms.
₃ , R ₄ , R ₇ , and R ₈ are preferably a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, or an aryl group.

Adjacent ones of R _{1 to} R ₁₀ are:
R ₂ and R ₃ , R ₃ and R ₄ , R ₄ and R ₅ , R ₆ and R ₇ , R ₇ and R ₈ , R ₈ and R ₉ may be combined with each other to form a ring. Are preferably combined with each other to form a nitrogen-containing heterocyclic ring, particularly preferably a 6-membered ring, and may further have a substituent such as an alkyl group.

[0034] X ^- include counter anion represented by, specifically a halide ion ^{(Cl -, Br -, I} - , etc.),
ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , VO ₃ ⁻ , VO ₄ ³⁻ , WO ₄
^2- , CH ₃ SO ₃ ⁻ , CF ₃ COO ⁻ , CH ₃ COO
_{^{-, HSO 4 -, CF 3}} SO 3 -, PO 4 · 12WO 3 3-,
Examples thereof include p-toluenesulfonic acid ion (PTS ⁻ ) and p-trimethyl phenylsulfonic acid ion (PFS ⁻ ). Among ^{them, Cl -, Br -, ClO} 4 -, BF
_4- ^{and the} like are preferred.

Further, an anion (anion) of an organometallic complex is mentioned as a preferable example. Such organometallic complexes include those known as metal complex quenchers. Specifically, acetylacetonate type, bisdithiol type such as bisdithio-α-diketone type and bisphenylenedithiol type, thiocatechol type,
Examples include anions of metal complexes such as salicylaldehyde oxime and thiobisphenolate. Among them, an anion of a bisphenylenedithiol-based metal complex is preferable. As the anion of the bisphenylenedithiol-based metal complex, an anion represented by the following formula (A) is preferable.

[0036]

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

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

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

Specific examples of the anion represented by the formula (A) are shown below, but the present invention is not limited thereto. Here, in accordance with the expression (A-a) or the like, the combination is represented by M, ^R01, or the like.

[0041]

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Further, an anion of a phenylazophenyl metal complex may be mentioned, and an anion of a metal complex of an azo compound represented by the following formula (BI) and a metal is preferable. In addition,
The metal complex having the azo compound of the formula (BI) as a ligand has a quencher function. Q ₁ -N = NQ ₂ (BI) In the formula (BI), Q ₁ and Q ₂ each represent an aromatic ring group having a group having active hydrogen at a position adjacent to the diazo group.

The formula (BI) will be described in more detail. The aromatic ring in the aromatic ring group having a group having an active hydrogen represented by Q ₁ or Q ₂ may be a carbocyclic or heterocyclic ring. May be a single ring, a condensed polycyclic ring or a polycyclic ring assembly. As such an aromatic ring,
Benzene ring, naphthalene ring, pyridine ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, quinoline ring, imidazole ring, pyrazine ring, pyrrole ring and the like, among which benzene ring,
A naphthalene ring and a pyrrole ring are preferred, and a benzene ring is particularly preferred.

The combination of Q ₁ and Q ₂ is preferably a combination of benzene rings, a benzene ring and a naphthalene ring, a benzene ring and a pyrrole ring, and more preferably a combination of benzene rings.

The bonding position of the group having active hydrogen in Q ₁ and Q ₂ in the aromatic ring is adjacent to the diazo group, and the groups having active hydrogen include —OH, —SH, and —NH.
_{2, -COOH, -CONH 2, -SO} 2 NH 2, -S
O ₃ H and the like are mentioned, and —OH is particularly preferable.

The aromatic ring represented by Q ₁ and Q ₂ may further have a substituent in addition to an azo group and a group having active hydrogen. A halogen atom (eg, a chlorine atom, a bromine atom, etc.), a carboxyl group, a sulfo group, a sulfamoyl group (preferably having 0 to 4 carbon atoms, such as sulfamoyl, methylsulfamoyl, etc.), an alkyl group (preferably having 1 to carbon atoms) And 4, for example, methyl) and an amino group.

When Q ₁ and Q ₂ are a combination of benzene rings, one of the benzene rings preferably has a nitro group or a halogen atom (preferably a chlorine atom or a bromine atom) as a substituent. Groups are preferred. Such a nitro group and a halogen atom are preferably present at the meta-position or the para-position of the diazo group, particularly preferably at the meta-position. Two or more substituents may be present,
In such a case, the substituents may be the same or different. In addition, the other benzene ring preferably has an amino group as a substituent, and the amino group may be an unsubstituted amino group, but is particularly preferably a dialkylamino group, and is preferably a dialkylamino group. The total carbon number is preferably 2 to 8, and examples include dimethylamino, diethylamino, methylethylamino, methylpropylamino, dibutylamino, hydroxyethylmethylamino and the like. The substitution position of such an amino group is preferably the para position of the diazo group.

The central metal of the metal complex having the azo compound of the formula (BI) as a ligand may be any one as long as the formed metal complex becomes an anion without a counter ion. The central metal is Co, vanadyl (V = O) or the like, and such a central metal and an azo compound ligand (ligand):
A complex of metal = 2: 1 is formed. In this case, the ligands may be the same or different.

It should be noted, based on the anion having an active hydrogen in the formula (B-I) (group having active hydrogen is when the -OH -O ^-) coordinated to the central metal in the form of.

Specific examples of the anion represented by the formula (BI) are shown below, but the present invention is not limited thereto. Here, a combination of an azo compound and a central metal is shown, where ligand: metal = 2: 1. Each of the specific examples is a monovalent anion, and those having two kinds of central metals are a mixture of anions of a metal complex having each metal as a central metal. Me, Et, and Bu in the specific examples represent methyl, ethyl, and butyl, respectively.

[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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

Among the anions of these organometallic complexes, the anion of a phenylazophenyl complex is particularly preferred for obtaining the optical constant required for the characteristics of the optical recording medium.

The xanthene dyes of the formula (I) used in the present invention are shown below, but the present invention is not limited to these. Here, some are shown according to the notation of the formula (Ia), and when X ⁻ is an anion of an organometallic complex, it is shown according to the notation exemplified above. Me, Et, iPr, and Bu are methyl, ethyl,
Indicates isopropyl.

[0059]

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[0060]

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[0061]

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[0062]

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Some of the xanthene dyes of the formula (I) are commercially available and can be synthesized by known methods.

[0064] Further, in order to obtain a xanthene dye having an anion of organometallic complex, ClO ₄ ^- salt, BF ₄ ^- After synthesizing the salt, depending on the anion of organometallic complex of interest,
Anions may be exchanged using a salt of an organometallic complex according to a known method.

The melting point (mp) of the xanthene dye of the present invention
Is 220 to 350 ° C., and λmax (measured with a dye thin film having a thickness of 50 nm) is in the range of 500 to 610 nm.

The real part (n) of the complex refractive index at a wavelength of 635 nm or 650 nm is 2.0 to 2.50, and the imaginary part (k) is 0.03 to 0.40.

The dyes n and k are determined by forming a dye film on a predetermined transparent substrate to a thickness of about the recording layer of an optical recording medium, for example, about 40 to 100 nm under the same conditions as the recording layer. Then, a measurement sample was prepared, and then the reflectance and transmittance at 635 nm or 650 nm of the measurement sample were measured. From these measured values, for example, according to Kyoritsu Zensho “Optics” Kozo Ishiguro P168-178, It is calculated. The reflectance is the reflectance of the measurement sample through the substrate or the reflectance from the dye film side, and is measured by specular reflection (about 5 °).

The xanthene dye of the present invention may be used alone or as a combination of two or more dyes for the recording layer.

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

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

After the spin coating as described above, the coating film is dried if necessary. The thickness of the recording layer formed in this manner is appropriately set according to the target reflectance and the like, but is usually 500 to 3000 A (50 to 3000 A).
300 nm).

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

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

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

As such a dye, preferably, a salt of an anion of the above-mentioned organometallic complex serving as a counter anion is exemplified. Regarding the salt of the anion of the formula (A), examples of the counter cation when forming the salt include ammonium ions such as tetrabutylammonium ion, Na ⁺ ,
Alkali metal ions such as K ⁺ are preferred.

Specific examples of the organometallic complex which is the salt of the formula (A) are shown below.

[0077]

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Further, there may be mentioned an anion salt of a metal complex having an azo compound of the formula (BI) as a ligand. In this case, the counter cation may be an inorganic salt such as Na ⁺ , Li ⁺ , K ^{+ and the} like. System cation, R ¹¹ R ¹² R ¹³ R ¹⁴ N ⁺ (where R
¹¹ , R ¹² , R ¹³ and R ¹⁴ each represent a hydrogen atom, an alkyl group, an alkoxy group or the like), R ¹¹ R ¹² R ¹³ N ⁺ -(CH ₂ ) _k -N ⁺ R
¹³ R ¹² R ¹¹ (where R ¹¹ , R ¹² and R ¹³ each represent a hydrogen atom, an alkyl group, an alkoxy group or the like, and k is 5 to 10).

Specific examples of such organometallic complexes which are salts of the formula (BI) are shown below.

[0080]

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Further, a compound of the formula (B-II) similar to the formula (BI)
A metal complex having an azo compound represented by the formula (1) as a ligand is also preferable. Q ₃ -N = N-Q ₄ (B-II) In the formula (B-II), Q ₃ represents an aromatic ring group having a group having active hydrogen adjacent to the diazo group, and Q ₄ represents a metal atom. It represents a nitrogen-containing heteroaromatic group having a coordinable N at a position adjacent to the carbon atom to which the diazo group in the ring is bonded.

The formula (B-II) will be described in more detail. The aromatic ring group having a group having an active hydrogen represented by Q ₃ has the same meaning as Q ₁ and Q ₂ in the formula (BI). belongs to.

The nitrogen-containing heteroaromatic ring in the nitrogen-containing heteroaromatic group having N in the ring, which can be coordinated to the metal atom represented by Q ₄ , may be a monocyclic ring or a condensed polycyclic ring. Good. Specific examples of such a nitrogen-containing heteroaromatic ring include a pyridine ring, a thiazole ring, a benzothiazole ring, an oxazole ring, a benzoxazole ring, a quinoline ring, an imidazole ring, a pyrazine ring, and a pyrrole ring. , A quinoline ring and a thiazole ring are preferred. The position of N in the ring is adjacent to the carbon atom to which the azo group is bonded. These may have a substituent similarly to Q ₁ and Q ₂ .

The combination of Q ₃ and Q ₄ is preferably a combination of a benzene ring and a pyridine ring, a benzene ring and a thiazole ring, a benzene ring and a quinoline ring, and the like.

The central metal in these metal complexes is C
o, vanadyl, Ni, Cu and the like are preferable.

These metal complexes are compounds that have no charge by themselves, or compounds that have a positive charge depending on the central metal or the like. When the compound has a positive charge, the counter ion is Cl ⁻ , Br ⁻ , I
^And the same counter anions as those represented by X ^{− in} the formula (I), such as halide ions such as ^— , ClO ₄ ⁻ and BF ₄ ^— .

The other points are the same as in the case of the formula (BI).

Hereinafter, specific examples of these metal complexes will be shown in combination with an azo compound and a central metal.

[0089]

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[0090]

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Each of the above metal complexes is a compound having a quencher function.

These compounds may be used alone or in combination of two or more.

In particular, the addition of such an organometallic complex is effective for further improving light resistance when the counter anion of the dye of the formula (I) is not an anion of the organometallic complex.

The mixing ratio of the dye of the formula (I) and the organometallic complex is 5: 1 in terms of molar ratio.
１ ： 1: 3 is preferred.

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

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

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

The ketones include cyclohexanone.

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

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

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

The substrate 12 or 22 is a disk-shaped one. In order to enable recording and reproduction from the back side of the substrate 12 or 22, recording light and reproduction light (wavelength 6
Laser light of about 00 to 680 nm, furthermore, about 630 to 680 nm, especially about 635 to 680 nm,
In particular, it is preferable to use a resin or glass which is substantially transparent (preferably at a transmittance of 88% or more) for 635 nm or 650 nm. The size is 64 in diameter.
The thickness is about 200 mm and the thickness is about 0.6 mm.

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

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

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

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

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

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

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

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

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

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

[0113]

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

Example 1 Dye I-1 was used as a dye for an optical recording layer, and had a pregroove (depth 0.12 μm, width 0.30 μm, groove pitch 0.74 μm) having a diameter of 120 mm and a thickness of 0.6.
A recording layer containing a dye is formed on a polycarbonate resin substrate having a thickness of 1000 A (100 nm) by a spin coating method.
It was formed in thickness. As a coating liquid in this case, 1.0 wt.
% 2,2,3,3-tetrafluoropropanol solution was used. Next, an Au reflection layer was formed on this recording layer to a thickness of 850 A by a sputtering method, and a transparent protective film (thickness: 5 μm) of an ultraviolet curable acrylic resin was formed. Two disks formed in the same manner were adhered with an adhesive with the protective films facing inward to produce a disk (see FIG. 1).

This is designated as Sample No. 1.

A sample was prepared in the same manner as in Sample No. 1 except that the dye or dye mixture shown in Table 1 was used instead of the dye I-1 as the dye for the recording layer. 1).

The samples Nos. 10 and 13 in Table 1
Reference numeral 15 denotes a combination shown in Table 1, in which a mixture of the dye of the formula (I) and the organometallic complex in a molar ratio of the dye of the formula (I): the organometallic complex = 7: 3 was used. Things.

[0118] For the sample thus produced,
A signal was recorded at a linear velocity of 3.5 m / s using a laser beam of 635 nm, and the disc was then recorded at a linear velocity of 3.5 m / s at 650 n
m Reproduced with laser light and evaluated for characteristics. Note that the lens aperture diameter NA was 0.60. Characteristics include reflectance at 650 nm, degree of modulation (14 TMod.), And jitter (Jitter).
r), the optimum recording power (P0) at 635 nm was evaluated.

The results are shown in Table 1.

[0120]

[Table 1]

From the results shown in Table 1, it is understood that the reflectance, the degree of modulation, and the jitter are all good.

Further, the light resistance of the samples Nos. 1 to 15 was examined. The light fastness was determined by irradiating a xenon lamp of 80,000 lux (Xenon fade meter manufactured by Shimadzu Corporation) for 40 hours and then measuring the jitter of the disk.

As a result, in Sample Nos. 1 to 15, the change in jitter was small. Sample No.1
Sample Nos. 6 to 12,
Although the change of the jitter was larger than that of the sample No. 14, the level was improved compared to the sample using the trimethine cyanine dye shown in Comparative Example 1 below. In particular, good results were obtained in Samples Nos. 6 to 12 and 14 using a salt-forming dye, and a dye having a counter anion having a preferable structure (I-6
To I-8, I-10, I-12, I-14), the jitter did not change at all.

Further, the above samples No. 1 to 15 were subjected to a reliability test at 80 ° C. and 80% RH for 100 hours.

As a result, the characteristics of Sample Nos. 6 to 12 and 14 were not deteriorated. Sample No.1
As for the samples Nos. 5, 13 and 15, the deterioration of the characteristics was larger than that of the above sample, but the level was improved as compared with the sample using the trimethine cyanine dye shown in Comparative Example 1 below.

Comparative Example 1 A disk sample was prepared in the same manner as in Example 1 except that the cyanine dye T1 (described below) was used. In the evaluation of the manufactured sample, sufficient light resistance was not obtained, and jitter during reproduction was greatly deteriorated. Modulation degree, reliability test,
Jitter deterioration was great.

[0127]

Embedded image

Comparative Example 2 A disk sample was prepared in the same manner as in Example 1 except that rhodamine dye R1 (described below) was used. In the evaluation of the prepared sample, recording was not possible due to poor sensitivity.

[0129]

Embedded image

[0130]

According to the present invention, by using a xanthene-based dye having excellent solubility as the light absorbing layer, it is possible to obtain an excellent balance between recording sensitivity, reflectance and modulation, and to provide high recording sensitivity and small jitter. An optical recording medium having excellent characteristics can be obtained. In particular, when a salt-forming dye of a xanthene dye cation and an anion of an organometallic complex is used as the xanthene dye, light resistance and reliability are improved.

[Brief description of the drawings]

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

[Explanation of symbols]

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

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Kadota 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation F term (reference) 2H111 EA03 EA12 EA22 EA25 EA33 EA37 EA39 EA43 EA44 FA01 FA12 FA37 FB42 FB63 2H123 AE07 4H056 BA02 BB05 BC01 BC04 BD01 BD03 BD05 FA05 5D029 JA04 JC17 JC20

Claims (4)

[Claims] 1. A recording and reproducing light having a wavelength of 680 nm or less, a recording layer containing a dye on a substrate, a reflective layer on the recording layer, and irradiating light to form pits. An optical recording medium for performing recording according to claim 1, wherein the recording layer contains a dye represented by the following formula (I). Embedded image [In the formula (I), A represents an atomic group forming a heterocyclic ring together with two carbon atoms to which it is bonded, Y represents a carboxylic acid group, a carboxylic ester group, a carbamoyl group, Represents a sulfonic acid group, a sulfonic acid ester group or a sulfamoyl group. R ₁ , R ₂ , R ₅ , R ₆ , R ₉
And R ₁₀ are each independently a hydrogen atom, a halogen atom, an amino group, a sulfonamide group, an amide group, a carbamoyl group, a nitro group, a sulfonic acid ester group, a carboxylic acid ester group, a nitrile group, or an alkyl group having 16 or less carbon atoms. , An alkoxy group or an alkenyl group. R ₃ ,
R ₄ , R ₇ and R ₈ each independently represent a hydrogen atom, a halogen atom, an aryl group, a heterocyclic group, or an alkyl or alkoxy group having 16 or less carbon atoms. R ₁ and R ₂ , R ₂
And R ₃ , R ₃ and R ₄ , R ₄ and R ₅ , R ₆ and R ₇ , R ₇ and R ₈ , R ₈
And R ₉ and R ₉ and R ₁₀ may be bonded to each other to form a ring. X ^- represents a counter anion. ] 2. The optical recording medium according to claim 1, wherein the counter anion represented by X ⁻ in the formula (I) is an anion of an organometallic complex. 3. The compound of formula (I) wherein A is 2
3. The optical recording medium according to claim 1, wherein the carbon atom forms a pyridine ring together with the two carbon atoms. 4. The optical recording medium according to claim 1, wherein the recording layer further contains a dye of an organometallic complex.