JP3115454B2 - Optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium such as an optical recording disk having a recording layer of a dye film.

[0002]

2. Description of the Related Art In recent years, various types of optical recording disks of the write-once type and the rewritable type have been receiving attention as large-capacity information carrying media. Some of such optical recording disks use a dye film containing a dye as a main component as a recording layer.
Conventionally, a so-called air sandwich structure in which an air layer is provided on a recording layer made of a dye film, which has been widely used, or a dye film that can be reproduced in compliance with the Compact Disc (CD) standard A structure having a structure in which a reflective layer is provided in close contact with a recording layer made of Nitrogen has been proposed (Nikkei Electronics, January 23, 1989, No. 4).
65, P107, Kinki Chemical Association Functional Dye Subcommittee, March 3, 1989, Osaka Science and Technology Center, PROC
EEDINGS SPIE-THE INTERNATIONAL SOCIETY FOR OPTICAL
ENGINEERINGVOL.1078 PP80-87, "OPTICAL DATA STORAGE
TOPICAL MEETING "17-19, JANUARY 1989 LOS ANGELES
etc).

[0003] Dyes used in such a recording layer include:
In view of heat resistance, water resistance and the like, indolenine-based cyanine dyes are preferably used (JP-A-59-24692).
No.).

However, such indolenine-based cyanine dyes have a disadvantage that, for example, in the case of a perchlorate having good solubility, reproduction deterioration due to repeated irradiation of reproduction light and light deterioration during storage in a bright room are likely to occur. . For this reason, it has been proposed to use a mixture of a dye and a metal complex quencher, which has been put to practical use (JP-A-59-59795). Among such metal complexes, particularly, bis (phenylenedithiol) -based Ni complexes and the like exhibit extremely excellent effects in terms of preventing reproduction deterioration and light deterioration of cyanine dyes.

However, the solubility is insufficient, and the alcohol system such as methanol has a solubility of 1% or less, and it is impossible to coat the recording layer using these solvents. Further, the absorption wavelength is 700 to 1000 nm, which affects the absorption of the dye, and as a result, the reflectance is reduced and the reproduction output is low.

Therefore, application of a dye excellent in light resistance by itself is desired.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium which is free from reproduction deterioration and light deterioration, has excellent light resistance, and can comply with the CD standard.

[0008]

This and other objects are attained by the present invention which is defined below as (1) and (2). (1) In an optical recording medium having a recording layer containing a dye on a substrate, the dye is composed of a dye cation and an anion of an inorganic atomic group containing vanadium represented by the following formula (3). An optical recording medium that is a renin-based cyanine dye.

[0009]

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[In the chemical formula 3, R ₁ and R ₂ each represent a hydrocarbon group, which may be the same or different. R ₃ and R ₄ each represent a hydrogen atom or a monovalent group bonded to the 4- to 7-positions of the indolenine ring, and may be the same or different, and when they are monovalent groups, R ₃ bonded to each other or R ₄ bonded to adjacent positions may be bonded to each other to form a ring. n represents 1, 2 or 3. X represents an anion of an inorganic atomic group containing vanadium, and m is a value necessary for neutralizing the charge of the dye cation. (2) The optical recording medium according to the above (1), wherein the recording layer further contains a quencher, and the quencher is a complex represented by Chemical Formula 4 or a dimer thereof.

[0011]

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[In the chemical formula 4, Cp represents cyclopentadiene. A represents C—R ² or N. R ¹ and R ² represent a hydrogen atom, an alkyl group, an aryl group, a cyano group, an ether group, an ester group, an acyl group, an alkylthio group, a sulfamoyl group, an alkylsulfonyl group, a heterocyclic group, a halogen atom or a nitro group, respectively. .
When A is C—R ² , R ¹ and R ² may combine with each other to form a ring. Y and Z are S, S, respectively
represents e, NR ³ or O. R ³ represents a hydrogen atom or an alkyl group. M represents a metal atom. ]

[0013]

[Specific Configuration] Hereinafter, a specific configuration of the present invention will be described in detail.

The optical recording medium of the present invention has a recording layer containing a dye on a substrate. The dye at this time is a dye represented by Chemical Formula 3, and is composed of a dye cation and an anion containing vanadium.

A dye having such an anion containing vanadium as a counter ion of the dye cation is excellent in light resistance, so that deterioration due to reproduction light of a medium and light deterioration due to storage in a bright room can be prevented. Therefore, although the solubility is good, the light resistance is remarkably improved as compared with a perchlorate or the like having poor light resistance.

The anion containing vanadium in the above is not particularly limited as long as it is an anion of an inorganic atomic group containing vanadium, and the valency of the anion is usually in the range of -4 to -1. The valence of vanadium is also +2 to +
5 may be used. Specifically, VO ₃ ⁻ , VO
₄ ^3- , V ₂ O ₇ ^4- , V ₄ O ₁₁ ^2- , VO ₂ (C ₂ O ₄ ) _{2
^{3-, VF 6 -, V 4}} O 9 2-, (VOF 4 (OH)
^{_{2) 2-, VO (C 2}} O 4) 2 2-, VO (SCN) 4 2-,
VO (SO ₄ ) ₂ ²⁻ , VF ₅ ²⁻ , V (SO ₄ ) ₂ ⁻ , V
^{_{(CN) 6 3-, V (}} CN) 6 4- , and the like. Of these, VO _3- ^{and the} like are particularly preferred.

In the present invention, an indolenine-based cyanine dye represented by Chemical Formula 3 is used.

Formula 3 will be described in more detail. R
₁ and R ₂ each represent a hydrocarbon group, and examples thereof include an alkyl group, a cycloalkyl group, and an aryl group. As the alkyl group, one having 1 to 4 carbon atoms is preferable, and examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the cycloalkyl group include a cyclohexyl group, and examples of the aryl group include a phenyl group. This may have a substituent, and examples of such a substituent include a halogen atom, an alkyl group, an aryl group, and an ether group. Of these, an unsubstituted alkyl group is preferable, and a methyl group and the like are particularly preferable.

R ₃ and R ₄ each represent ₄ of the indolenine ring
Represents a hydrogen atom or a monovalent group bonded to the 7th to 7th positions. As the monovalent group, a substituted or unsubstituted alkyl group, aryl group, alkoxy group, amino group or heterocyclic group,
Halogen atoms and the like can be mentioned, and among these monovalent groups, those that can be substituted may have a substituent. When it has a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, and a heterocyclic group.

When R ₃ and R ₄ are monovalent groups,
R ₃ bonded to adjacent positions or R ₄ bonded to adjacent positions may be bonded to each other to form a ring, and the formed ring is preferably a carbocyclic ring;
Particularly, a benzene ring is preferable.

N represents 1, 2 or 3, and particularly preferably 2.

It is preferred that R ₃ and R ₄ each form a hydrogen atom or a benzene ring formed by adjacent R ₃ or R ₄ .

X represents an anion of an inorganic atomic group containing vanadium, and examples thereof are the same as those described above. Particularly preferred is VO _3- ^{and the} like.

M is a value required to neutralize the charge of the dye cation, and depends on X and the valence of the dye cation.

In the dye represented by Chemical formula 3, substituents on the benzene ring of the indolenine ring, for example, R _{3 at the} adjacent position
When condensed by bonding together to form a benzene ring, the benzene ring is preferably condensed at the 4- and 5-positions.

Specific examples of the dye represented by Formula 3 are shown below.

[0027]

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[0028]

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[0029]

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[0030]

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In each of Chemical formulas 5 to 8, R ₁ , R
₂ , X and m have the same meanings as in Chemical formula 3. In the chemical formula 5, R ₁₃ and R ₁₄ may be the same or different, respectively, and each represents a hydrogen atom or R ₃ , R ₄
And the same as the monovalent group represented by, and both are preferably hydrogen atoms. R ₃₄ in Chemical Formula 7 and R ₄₃ in Chemical Formula 8 have the same meanings as R ₁₃ and R ₁₄ in Chemical Formula 5, respectively, and are preferably hydrogen atoms. R ₃₄ , R ₄₃
Is preferably a monovalent group, these groups are preferably bonded to the 5-position of the indolenine skeleton, and a hydrogen atom is preferably bonded to the 4-, 6-, and 7-positions. Preferred examples of the group include an alkyl group such as a methyl group. In Chemical Formulas 5 to 8, R
_1, also shown an example of combining R ₂ and the like. Note that R ₁₃ , R
_When all of the positions 4 to 7 are hydrogen atoms, each of ₁₄ , R ₃₄ and R ₄₃ is represented by H, and the exemplified compound (7-1) of Chemical formula 7
Indicates that R ₃₄ bonded to the 5-position is CH ₃ and H-positions 4, 6, and 7 are H.

The dye of formula (3) is synthesized by known methods such as halides (bromide, iodide, etc.), perchlorates, paratoluenesulfonates, tetrafluoroborates, and the like, followed by salting. It may be exchanged. The vanadium compound used for the salt exchange may be one corresponding to a desired anion. For example, when a VO ₃ salt is used, N
aVO ₃ , KVO _3, etc., when used as VO ₄ salt, NaVO
₄ or the like may be used. In the salt exchange, a saturated solution of a dye and a saturated solution of a vanadium compound such as NaVO ₃ may be mixed using a solvent such as methanol, and crystals may be precipitated and taken out. The solvent used for the saturated solution at this time is generally preferably the same, but may be different depending on the case. The capacitance ratio of the dye solution and the vanadium compound solution usually dye solution / vanadium compound solution (V ₁ / V ₂₎ may be such that the 1 / 5-5 / 1. The temperature at the time of preparing a saturated solution and at the time of mixing the two solutions is preferably 40 ° C. or less in consideration of the stability of the dye and the vanadium compound, and is usually 10 ° C. or less.
-30 ° C is preferred.

For example, the exemplified compound (6-1) of Chemical formula 6 is
A methanol-saturated solution of paratoluenesulfonic acid salt of the corresponding dye cation and a methanol-saturated solution of NaVO ₃ are prepared at 25 ° C., and these solutions are mixed to precipitate crystals.

Further, the exemplified compound (7-1) of Chemical formula 7 is obtained by converting the paratoluenesulfonic acid salt of the corresponding dye cation into bromide by a known method, and then converting the exemplified compound (6-).
It is obtained in the same manner as in 1).

The dye of Chemical Formula 3 has an absorption maximum of 600 to 900.
It is about nm. Accordingly, high reflection can be obtained at the wavelength of the semiconductor laser, which is suitable for use in an optical recording disk or the like compliant with the CD standard.

The dye of formula 3 may be used alone or in combination of two or more. Further, in the present invention,
It is preferable to use only the above dye, but in some cases, other dyes can be used in combination.

The content of the dye of formula 3 in the recording layer may be 10 to 100% by weight of the entire recording layer, and the recording layer may be coated using a coating solution containing the dye and an organic solvent. In particular, when coating the recording layer of an optical recording disc,
It is preferable to use a spin coating method in which a coating solution is spread and applied on a rotating substrate.

The organic solvent used in the coating solution for forming the recording layer may be appropriately selected from keto alcohols, ketones, esters, ethers, cellosolves, aromatics, alkyl halides and the like. In particular, it is preferable to use a keto alcohol (such as diacetone alcohol) or a cellosolve (such as methyl cellosolve or ethyl cellosolve). Considering the solubility of the dye, halogenated alcohols, particularly fluorinated alcohols (2, 2 , 2-
Trifluoroethanol, 2,2,3,3,3-pentafluoro-1-propanol, 2,2,3,3,4
4,4-heptafluoro-1-butanol, 2,2
It is also preferable to use 3,3-tetrafluoro-1-propanol and the like.

After spin coating, the coating film is dried if necessary. The thickness of the recording layer formed in this way is appropriately set according to the target reflectance and the like, but is usually about 1000 to 3000 A.

The content of the pigment in the coating solution is as follows.
The content is 5 to 15% by weight, preferably 1.8 to 10% by weight. Note that the coating liquid may appropriately contain a binder, a dispersant, a stabilizer and the like.

In the present invention, the quencher of Chemical Formula 4 can be used together with the dye of Chemical Formula 3. The quencher of Chemical formula 4 has a higher solubility in an organic solvent of a coating solution for forming a recording layer and has less influence on the absorption characteristics of the dye of Chemical formula 3 as compared with a conventionally used bisdithiol-based metal complex. Excellent.

The complex quencher represented by Chemical Formula 4
To explain, in the chemical formula 4, Cp is cyclopentadiene
It is. Cyclopentadiene has 1 to 5 substituents
May be substituted or unsubstituted
An alkyl group having 1 to 4 carbon atoms (-CH_Three , -C_Two H
_Five , -CF_Three , -C_Two F_Five Etc.), substituted or unsubstituted
An aryl group (such as a phenyl group), a cyano group,
Unsubstituted ether group (-OCH_Three , -OCF_Three Etc.), place
A substituted or unsubstituted ester group (—COOCH _Three , -C
OOC_Two H_Five Etc.), a substituted or unsubstituted acyl group (-
COCH_Three Etc.), substituted or unsubstituted alkylthio groups
(-SCH_Three , -SCF_Three Etc.), substituted or unsubstituted
Sulfamoyl group (-SO_Two NH_Two Etc.), replacement or
Unsubstituted alkylsulfonyl group (-SO_Two CH_Three , -S
O_Two CF_Three Etc.), halogen atoms (F, Cl, Br, I
Etc.), a nitro group and the like. Also these substitutions
Where possible, cycloalkanes (cyclohexyl)
To form a ring such as
It may be condensed.

Y and Z coordinated to the metal atom M may be the same or different from each other, and are S, Se, and N, respectively.
Represents R ³ or O. Among these, combinations of Y + Z include S + S, Se + Se, S + Se, and NR ³
A combination of + NR ³ , S + NR ³ , and S + O is preferable. R ³ represents a hydrogen atom or, preferably, an alkyl group having 1 to 4 carbon atoms.

A which forms a 5-membered ring together with M, X, Y and CR ¹ represents CR ² or N. R ¹ and R ² represent a hydrogen atom, an alkyl group, an aryl group, a cyano group, an ether group, an ester group, an acyl group, an alkylthio group, a sulfamoyl group, an alkylsulfonyl group, a heterocyclic group, a halogen atom or a nitro group. These R ¹
And R ² represent a halogen atom such as fluorine or chlorine, a nitro group, preferably an alkyl group having 1 to 4 carbon atoms, an aryl group, preferably an alkoxy group having an alkyl group having 1 to 4 carbon atoms, substituted or It may be further substituted with an unsubstituted amino group or the like.

Preferred examples of R ¹ and R ² include:
Hydrogen atom; an alkyl group having 1 to 4 carbon atoms (—CH ₃ ,
_{-C 2 H 5, -C 3 H} 7, -C 4 H 9, -CF 3 , etc.);
An ether group having an alkyl group having 1 to 4 carbon atoms (-
OCH _3, -OCF _3, etc.); an ester group having an alkyl group of 1 to 4 carbon atoms (-COOCH _3, -COOC
₂ H ₅ and the like); an acyl group having an alkyl group of 1 to 4 carbon atoms (-COCH _3, etc.); an alkylthio group (-SCH ₃ having an alkyl group of 1 to 4 carbon atoms, -SCF ₃
Etc.); a sulfamoyl group (-SO ₂ NH _2, etc.); an alkylsulfonyl group having an alkyl group of 1 to 4 carbon _{atoms, (- SO 2 CH 3,} -SO 2 CF 3 , etc.); NO _2;
CN; an aryl group having 6 to 12 carbon atoms (phenyl group,
a heterocyclic group (2-pyridine group, 3-pyridyl group, 4-pyridyl group; halogen atom (F, Cl, Br, etc.) and the like.

R ¹ and R ² are usually the same, but may be different from each other. R ¹ and R ² may combine with each other to form a ring, for example, an aromatic ring such as a benzene ring and a naphthalene ring. In addition, a substituent such as an alkyl group, an aryl group, a halogen, a substituted or unsubstituted amino group, or an alkoxy group may be further bonded to the ring.

Further, M is a metal atom, for example, Co, N
i, Pt, Zn, Cu, Rh, etc. The complex of Chemical formula 4 may be a dimer as shown in Chemical formula 9.

[0048]

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In Chemical Formula 9, Cp, M, Y, Z and R ¹ have the same meanings as in Chemical Formula 4.

Among the complex quencher of Chemical Formula 4, Chemical Formula 10
The complex quencher represented by is preferred. In the case of Chemical Formula 10, the degree of modulation is further increased.

[0051]

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In Chemical Formula 10, Cp represents cyclopentadiene as in Chemical Formula 4, and has the same meaning as in Chemical Formula 4. When the cyclopentadiene has a substituent, examples of the substituent include a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms (such as —CH ₃ , —C ₂ H ₅ , and —CF ₃ ); An ester group having an alkyl group having 1 to 4 carbon atoms (such as —COOCH ₃ ), an acyl group having a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms (—CO
CH ₃ etc.), a nitro group, a halogen atom and the like.

M ¹ represents Co, Ni or Rh, and particularly preferably Co.

Y ¹ and Z ¹ are each S or Se
And may be the same or different.

R ¹¹ and R ¹² each represent a hydrogen atom or a monovalent substituent having a Hammett sigma (σ) value of 0 or more. Specifically, among the compounds represented by R ¹ and R ² in Chemical Formula 4, those having a Hammett sigma (σ) value of 0 or more are represented by —CF ₃ , —CN, —OCF ₃ , and —COOCH.
_{3, -COOC 2 H 5, -SCF} 3, -NO 2, -SO
₂ NH ₂ , —SO ₂ CH ₃ , a halogen atom, a hydrogen atom, and the like are preferable. If possible, R ¹¹ and R ¹² may combine to form a ring.

In the complex quencher of Chemical formula 4,
Preferred are M, Y, Z, C, A, including those of
(In the chemical formula 10, the ring formed by M ¹ , Y ¹ , Z ¹ , C, C) has aromaticity. The aromatic character of the ring formed by these is confirmed from the ¹³ C chemical shift (δ) value of cyclopentadiene by ¹³ C NMR, the reduced half-wave potential (E ^r _1/2 ) value of the polarogram, and the like. .

For example, in a dithiol ring in which both Y (or Y ¹ ) and Z (or Z ¹ ) are S, the E ^r _1/2 value is −
1.8 to OV, and the ¹³ C δ value is 75 to 90 ppm. When the δ value is plotted against the E ^r _1/2 value, a linear relationship is shown, and the slope △ (δ / E ^r _1/2 ) is 2.0 to
It is in the range of 15.0 (ppm / V). In addition, E ^r _1/2 was measured using a reference electrode (A) using tetraethylammonium perchlorate (TEAP) as a supporting electrolyte in acetonitrile.
g | 0.1 mol dm ^{-3 (} AgClO ₄ )
It was determined by measuring at ° C.

In terms of light resistance, the substituent when Cp is substituted has a Hammett sigma (σ) value of 0.
The above are preferable, and further, R ¹ (or R ¹¹ ),
R ² (or R ¹² ) also preferably has a Hammett sigma (σ) value of 0 or more.

It is preferable to use a complex quencher of formula 4 having a maximum absorption of 600 nm or less, particularly 550 to 560 nm. By using such a wavelength region, the reflectance does not decrease and the reproduction output does not decrease.

Specific examples of the complex quencher of Chemical formula 4 are described in Japanese Patent Application Nos. 4-269449 and 5-60890 by the present applicant. Regarding the synthesis method, see Sugimori Akira, Ushika, 48,788 (199).
0) Akira Sugimori, OrganometallicsNews, 1990, No. 1, P2 H. Boennemann, B. Bogdanovic, W. Brijoux, R. Brinkman
n, M. Kajitani, R. Mynott, GSNatarajan and MGSan
son "Transition-Metal-Catalyzed Synthesis of Heter
ocyclic Compounds "in" Catalysis in Organic React
ions "ed. by JRKosak, Marcel Dekker, 1984, P31-
62. and the description in the above-mentioned application specification can be referred to.

In the present invention, the complex quencher represented by Chemical Formula 4 is usually used in an amount of 0.1 to 10 mol per mol of the dye. In addition, in addition to the quencher of Chemical formula 4, other known quencher may be used in combination.

When the complex quencher of Chemical formula 4 is used, the complex quencher of Chemical formula 4 may be added to the above-mentioned coating solution for forming a recording layer, and the content of the quencher in the coating solution is 0.5. 10 to 10% by weight, preferably 1 to 8% by weight.

FIG. 1 shows an example of the structure of an optical recording disk having such a dye film as a recording layer on a substrate serving as a base. FIG. 1 is a partial sectional view. The optical recording disk 1 shown in FIG. 1 is a contact-type optical recording disk having a reflective layer adhered on a recording layer and capable of reproducing data in compliance with the CD standard. As shown in the figure, the optical recording disk 1 has a recording layer 3 containing the above-mentioned dye as a main component on the surface of the substrate 2, and is in close contact with the recording layer 3 to form a reflective layer 4.
It has a protective film 5.

The substrate 2 is in the form of a disk. To enable recording and reproduction from the back side of the substrate 2,
Recording light and reproduction light (semiconductor laser light having a wavelength of about 600 to 900 nm, particularly about 770 to 900 nm,
80 nm), which is substantially transparent (preferably a transmittance of 88
% Or more) using a resin or glass. The size is about 64 to 200 mm in diameter and about 1.2 mm in thickness.

As shown in FIG. 1, a tracking groove 23 is formed on the surface of the substrate 2 on which the recording layer 3 is formed.
The groove 23 is preferably a spiral continuous groove, having a depth of 0.1 to 0.25 μm, a width of 0.35 to 0.50 μm, and a groove pitch of 1.5 to 0.5 μm.
It is preferably 1.7 μm. With such a configuration of the groove, a good tracking signal can be obtained without lowering the reflection level of the groove portion. In particular, it is important to limit the groove width to 0.35 to 0.50 μm. If the groove width is less than 0.35 μm, it is difficult to obtain a tracking signal of a sufficient size, and a slight offset of the tracking during recording. As a result, jitter tends to increase. 0.50μm
Exceeding the limit causes waveform distortion of the reproduced signal to occur easily, which causes an increase in cross stroke.

The material of the substrate 2 is preferably a 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 23 is preferably formed when the substrate 2 is formed. After the manufacture of the substrate 2, a resin layer having the groove 23 may be formed by a 2P method or the like. In some cases, a glass substrate may be used.

As shown in FIG. 1, the recording layer 3 provided on the substrate 2 is formed by using the above-mentioned dye-containing coating solution and preferably by the spin coating method as described above. The spin coating may be performed under normal conditions, for example, by adjusting the rotation speed from 500 to 5000 rpm from the inner circumference to the outer circumference.

The thickness of the recording layer 3 thus formed is 500 to 3000 A (50 to 300 n
m) is preferable. Outside this range, the reflectivity decreases, making it difficult to perform reproduction in compliance with the CD standard. At this time, the thickness of the recording layer 3 in the recording track in the groove 23 is set to 1000 A (100 nm) or more,
If it is 0 to 3000 A (150 to 300 nm), the modulation degree becomes extremely large.

The recording layer 3 formed in this manner has C
When recording a D signal, the extinction coefficient (imaginary part of the complex refractive index) k of the recording light and the reproduction light wavelength is 0.02 to 0.02.
It is preferably 0.05. When k is less than 0.02, the absorptivity of the recording layer decreases, and it is difficult to perform recording with normal recording power. On the other hand, if k exceeds 0.05, the reflectivity falls below 70%, making it difficult to perform reproduction according to the CD standard. Further, the refractive index (real part of the complex refractive index) n of the recording layer 3 is 2.0 to 2.6. When n <2.0, the reflectance is reduced, and the reproduced signal is reduced, so that the reproduction according to the CD standard tends to be difficult.

As shown in FIG. 1, on the recording layer 3,
The reflection layer 4 is provided in close contact with the substrate. The reflective layer 4 is preferably made of a high-reflectance metal or alloy such as Au or Cu. The thickness of the reflective layer 4 is preferably 500 A or more, and may be provided by vapor deposition, sputtering, or the like. The upper limit of the thickness is not particularly limited, but is preferably about 1200 A or less in consideration of cost, production operation time and the like. Thereby, the reflectance of the reflection layer 4 alone becomes 9
0% or more, the reflectance of the unrecorded portion of the medium through the substrate is:
60% or more, especially 70% or more, is obtained.

As shown in FIG. 1, on the reflective layer 4,
A protective film 5 is provided. The protective film 5 is made of, for example, various resin materials such as an ultraviolet curable resin, and is usually 0.5 to 100 μm.
It may be formed to a thickness of about m. The protective film 5 may be in the form of a layer or a sheet. The protective film 5 may be formed by an ordinary method such as spin coating, gravure coating, spray coating, dipping, or the like.

The optical recording disk of the present invention is not limited to a contact type optical recording disk as shown in the figure, but may be any optical disk having a recording layer containing a dye. Examples of such a disk include a pit-formed optical recording disk having an air sandwich structure, and similar effects can be obtained by applying the present invention.

[0073]

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

Example 1 First, on a glass substrate having a diameter of 50 mm and a thickness of 1.2 mm, a diacetone alcohol (DAA) solution containing 2 wt% of the exemplified compound (7-1) of Chemical Formula 7 was spin-coated. A sample No. 1 was obtained. The thickness of the dye film was 60 nm.

[0075] Also, in sample No. 1, exemplified compounds of the dye of 7 (7-1) Exemplified Compound from at (7-1) X = ClO ₄ ^- except for changing to what was in the same manner Sample No. 2 was produced.

Sample No. 1, No. For 2 was measured each initial transmission T _o. Further irradiate a xenon lamp of 80,000 lux, measure the transmittance T after irradiation,
To calculate the dye residual rate in the (100-T) × 100 / (100-T o).

The residual dye ratio was determined after 15 hours and after 40 hours. The results are as shown below.

Sample (counter ion) After 15 hours and after 40 hours No. 1 (VO ₃ ⁻ ) 75% 60% No. 2 (ClO ₄ ⁻ ) 72% 14% (colorless)

It can be seen that the dye of formula 3 is excellent in light resistance.

Next, an optical recording disk sample No. 1 having the structure shown in FIG. 1 was manufactured by using the dye used in the sample No. 1 for the recording layer. First, a recording layer containing a dye was formed on a polycarbonate resin substrate having a diameter of 120 mm and a thickness of 1.2 mm by a spin coating method. On this recording layer, a reflective layer was formed, and a protective film was further formed.

The coating solution used for forming the recording layer 3 was the same as the dye solution used in Sample No. 1 described above, and the dye content was 6 wt%. The thickness of the recording layer is 2
00 nm. The reflective layer was made of Au, and was formed to a thickness of 85 nm by a sputtering method. Then, a UV-curable acrylic resin protective film (5 μm thick) was formed thereon.

For the above disk sample No. 1, 7
The reflectance at 80 nm was measured. As a result, the reflectance is 67
%, Which is sufficient for the CD standard.

From the above, it can be seen that the use of the dye of formula (3) makes it possible to realize an optical recording disk whose light resistance is remarkably improved and which can sufficiently comply with the CD standard.

Example 2 A sample was prepared in the same manner as in Example 1 except that the dye was changed to the exemplified compound (6-1) of Chemical formula 6.
No. 21 was produced. Further, in the sample No. 21, exemplified compounds of the dye of 6 (6-1) Exemplified Compound from at (6-1) X = ClO ₄ ^- except for changing to what was in the same manner Sample No. 22 Was prepared.

With respect to Samples No. 21 and No. 22, the dye residual ratios after 10 hours and 50 hours were determined in the same manner as in Example 1. The results are shown below.

Sample (counter ion) 10 hours later 50 hours later No. 21 (VO ₃ ⁻ ) 82% 67% No. 22 (ClO ₄ ⁻ ) 70% 14% (decoloration)

It can be seen that the dye of formula 3 is excellent in light resistance.

Next, an optical recording disk sample No. 21 was prepared in the same manner as in Example 1 except that the dye used in the sample No. 21 was used for the recording layer. At this time, the dye content of the coating solution for the recording layer was 6 wt%.

With respect to the above disk sample No. 21,
When the reflectance at 780 nm was measured, the reflectance was 70%.
Met.

From the above, it can be seen that the use of the dye of formula 3 markedly improves the light fastness and sufficiently complies with the CD standard.

Example 3 In the sample No. 1 of Example 1, except for the dye,
Using the Co complex quencher of No. 1 and the dye and Co
Sample No. 31 was prepared in the same manner except that the total amount of the complex quencher was 2 wt%. The ratio between the dye and the Co complex quencher was such that the weight ratio of the dye / Co complex quencher was 85/15. This sample N
In o.31, it was confirmed that the light resistance was sufficient.

[0092]

Embedded image

Next, an optical recording disk sample No. 31 was prepared in the same manner as in Example 1 except that the dye and the Co complex quencher used in the sample No. 31 were used for the recording layer. However, the ratio of the dye to the Co complex quencher in the coating solution for the recording layer was the same as described above.

With respect to the above disk sample No. 31,
When the reflectance at 780 nm was measured, it was found that the reflectance was sufficient, and that it could sufficiently comply with the CD standard.

[0095]

According to the present invention, reproduction deterioration and light deterioration can be prevented, and light resistance is excellent. In addition, it is fully compatible with the CD standard.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an example of an optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 Substrate 23 Groove 3 Recording layer 4 Reflective layer 5 Protective film

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-216966 (JP, A) JP-A-1-234293 (JP, A) JP-A-2-663 (JP, A) JP-A-2- 39989 (JP, A) JP-A-6-309697 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/26 CAPLUS (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. An optical recording medium having a recording layer containing a dye on a substrate, wherein the dye comprises a dye cation and an anion of an inorganic atomic group containing vanadium represented by the following chemical formula 1. An optical recording medium that is an indolenine-based cyanine dye. Embedded image [In the chemical formula ₁ , R ₁ and R ₂ each represent a hydrocarbon group and may be the same or different.
R ₃ and R ₄ each represent 4 to 7 of the indolenine ring
Represents a hydrogen atom or a monovalent group bonded to the position, each may be the same or different, and when it is a monovalent group,
R ₃ bonded to adjacent positions or R ₄ bonded to adjacent positions may be bonded to each other to form a ring. n represents 1, 2 or 3. X represents an anion of an inorganic atomic group containing vanadium, and m is a value necessary for neutralizing the charge of the dye cation. ] 2. The optical recording medium according to claim 1, wherein the recording layer further contains a quencher, and the quencher is a complex represented by Chemical Formula 2 or a dimer thereof. Embedded image [In the chemical formula 2, Cp represents cyclopentadiene.
A represents C—R ² or N. R ¹ and R ² are
Each represents a hydrogen atom, an alkyl group, an aryl group, a cyano group, an ether group, an ester group, an acyl group, an alkylthio group, a sulfamoyl group, an alkylsulfonyl group, a heterocyclic group, a halogen atom or a nitro group. A is CR
^When it is ² , R ¹ and R ² may combine with each other to form a ring. Y and Z represent S, Se, NR ³ or O, respectively. R ³ represents a hydrogen atom or an alkyl group. M represents a metal atom. ]