JP2000265076A - Cyanine colorant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a colorant which is useful as a recording material for a recording layer of an information recording medium by selecting a cyanine colorant having a benzindolenine backbone. SOLUTION: This cyanine colorant is represented by the formula [wherein R1 is a (1-12C alkoxy-substituted) 1-12C alkyl; R2 and R3 are each H, a 1-12C alkyl, 1-12C alkoxy or halogen; R4 is H, a 1-12C alkyl, halogen or pyridyl; and X- is Cl-, Br-, I-, ClO-, BF6-, BF4-, CF3SO3-, p-toluenesulfonate or naphthalenedisulfonate]. An optical disk prepared by forming a recording layer from the cyanine colorant on a substrate and forming a reflection layer on the recording layer exhibits a high reflectance and is excellent in recording and reproduction characteristics such as recording sensitivity, C/N, etc.; that is, the recording layer formed from the colorant has a max. absorption wavelength at the short-wavelength side of about 710 nm and exhibits a relatively small light absorption when laser light having an oscillation wavelength of about 780 nm is used, remarkably enhancing the reflectance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel cyanine dye. The present invention particularly relates to a cyanine dye useful as a recording material for a recording layer in an information recording medium in which information can be written using a laser beam.

[0002]

2. Description of the Related Art In recent years, information recording media using a beam of high energy density such as laser light have been developed and put into practical use. This information recording medium is called an optical disk, and is used as a video disk, an audio disk, a large-capacity still image file, a large-capacity computer disk memory, and the like.

[0003] A DRAW (Direct Read After Write) type optical disk has, as its basic structure, a disk-shaped substrate made of glass, synthetic resin, or the like, and Bi, S provided thereon.
a recording layer made of a metal or semimetal such as n, In, Te, or the like; or a dye such as cyanine, metal complex, or quinone. In addition, on the substrate surface on the side where the recording layer is provided,
In order to improve the flatness of the substrate, the adhesion to the recording layer, or the sensitivity of the optical disc, an intermediate layer made of a polymer substance may be provided. Writing information on an optical disc is performed by irradiating the optical disc with a laser beam. The irradiated portion of the recording layer absorbs the light and locally raises the temperature, causing a physical or chemical change (for example, a pit). ) Occurs and information is recorded by changing its optical properties. Reading of information is also performed by irradiating an optical disk with a laser beam, and information is reproduced by detecting reflected light or transmitted light corresponding to a change in the optical characteristics of the recording layer.

As a recording material for forming a recording layer of such an information recording medium, metals and dyes are known as described above. An information recording medium using a dye has advantages in characteristics of the recording medium itself, such as higher sensitivity than a recording material such as a metal, and also has a manufacturing advantage that a recording layer can be easily formed by a coating method. Has great advantages. However, a recording layer made of a dye generally has disadvantages such as low reflectivity and low reproduction signal C / N, and disadvantages such as the dye recording layer being easily deteriorated with time by light irradiation. I have.

As a recording layer comprising a dye having improved reflectance and C / N, a cyanine dye having a benzoindolenine skeleton (a structure in which a benzene ring is condensed with an indolenine skeleton) is disclosed in JP-A-64-40382. An optical disc having a recording layer made of is disclosed. The above publication discloses a dicarbocyanine dye in which, among cyanine dyes having a benzoindolenine skeleton, a methine chain connecting two benzoindolenine skeletons has five unsubstituted methine groups. . However, according to the study of the present inventors, the information recording medium having such a dye recording layer is relatively good in C / N, but not satisfactory in reflectance and light resistance. Absent.

[0006] In order to increase the reflectance, it is common practice to further provide a reflective layer on the dye recording layer. An example of this is “Nikkei Electronics” (p. 107,
According to this, the dye used in the recording layer of the recording medium is unknown, but the recording method is such that the dye is absorbed by the dye recording layer by laser absorption. It is disclosed that the melting is performed, and the plastic substrate is heated in accordance with the melting, and the substrate is raised to the recording layer side to form pits. This reflection layer is a deposited film of gold. And EPC
Japanese Patent Publication No. 0353393 discloses that the cyanine dye having a benzoindolenine skeleton is used for the dye recording layer of the optical disk with a reflective layer.
Thereby, an optical disk having a relatively high C / N and an improved reflectance can be obtained.

[0007] Even in a DRAW type optical disc, in the case of high-density recording of a CD format signal (CD-DRAW), it is necessary to record the signal at a low constant speed of 1.2 to 1.4 m / sec. Record the recorded signal on a commercially available CD.
It is required to be played on a player. For reproduction on a CD player, it is preferable that the reflectivity of the optical disk is at least 70%. However, according to the study of the present inventors, even if a CD format signal is recorded on an optical disc having a recording layer of a cyanine dye having a benzoindolenine skeleton and a reflective layer, there are some CD players which cannot reproduce the CD format signal. . Further, in order to improve the light resistance of the recording layer, diimmonium, aminium, metal complex dyes may be added to the above-described dyes, and the reflectance of the recording layer at this time generally tends to decrease. It was found that it was difficult to obtain both high reflectance and excellent light resistance. Therefore, the CD-
It is desired that an optical disk having excellent recording / reproducing characteristics and a remarkably high reflectivity (about 80%) as a DRAW appears.

[0008]

An object of the present invention is to provide a cyanine dye having a novel benzoindolenine skeleton. The present invention also relates to an information recording medium having a recording layer and a reflective layer thereon, which is a novel benzoindolenine useful as a recording material for the recording layer of an information recording medium having significantly improved C / N and reflectance. An object is to provide a cyanine dye having a skeleton. Another object of the present invention is to provide an information recording medium using a cyanine dye represented by the general formula (I) as a recording material of a recording layer of an information recording medium having a recording layer and a reflective layer thereon. I do.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
The invention is achieved by the following inventions. (1) The following general formula (I):

Embedded image [In the formula, R ₁ represents an alkyl group having 1 to 12 carbon atoms. The alkyl group for R ₁ may be substituted with an alkoxy group having 1 to 12 carbon atoms. R ₂ and R ₃ each independently represent hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a halogen group. R ₄
Represents hydrogen, an alkyl group having 1 to 12 carbon atoms, a halogen group, or a pyridyl group. Then, X ^- is, Cl ^-, Br
^{_{-, I -, ClO 4 -}} , PF 6 -, BF 4 -, CF 3 S
O ₃ ⁻ , represents paratoluenesulfonate or naphthalenedisulfonate. And a cyanine-based dye having a benzoindolenine skeleton. (2) The cyanine dye according to the above (1), wherein R ₂ is hydrogen in the general formula (I). (3) The cyanine dye according to the above (1), wherein in the general formula (I), R ₃ is hydrogen.

(4) An information recording medium using the cyanine dye described in (1) above as a recording material for a recording layer of an information recording medium having a recording layer and a reflective layer thereon.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The novel cyanine dye of the present invention is a cyanine dye having a benzoindolenine skeleton represented by the above general formula (I), and its characteristics are higher than those of conventionally disclosed dyes. The point where the maximum absorption wavelength is a long wavelength. The novel cyanine dye is useful as a recording material for a recording layer of an information recording medium. In particular, it is useful as a recording material for an information recording medium having a basic structure in which a substrate, a recording layer thereon, and a reflective layer are further provided on the recording layer. The present inventors have sought a dye that can be used in the recording layer of the above-mentioned optical disk with a reflective layer, and that the obtained optical disk has excellent recording / reproducing characteristics such as high C / N and high reflectance. I have been studying hard. As a result, it has been found that the above can be realized by using a cyanine dye having a benzoindolenine skeleton represented by the above general formula (I) as a recording layer. That is, the cyanine dye of the present invention represented by the general formula (I) can change its absorption maximum to a short wavelength side or a long wavelength side by changing its structure.
Many of the above dyes have a high reflectance in a wavelength band around 780 nm, which is the oscillation wavelength of general laser light,
/ N and the degree of modulation were also high.

The information recording medium of the present invention can be manufactured by the following method. The substrate of the information recording medium of the present invention can be arbitrarily selected from various materials used as the substrate of the conventional information recording medium. Examples of the substrate material include glass; polycarbonate; acrylic resins such as polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer; epoxy resins; amorphous polyolefin and polyester; You may use them together. Note that these materials can be used in the form of a film or a rigid substrate.
Among the above materials, polycarbonate is preferred from the viewpoints of moisture resistance, dimensional stability, cost, and the like.

An undercoat layer may be provided on the surface of the substrate on which the recording layer is provided, for the purpose of improving flatness, improving adhesive strength, and preventing deterioration of the recording layer. Examples of the material of the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylolacrylamide, styrene / vinyltoluene copolymer, and chlorosulfonate. Polymeric substances such as polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, polycarbonate, etc .; and silane coupling agents And other organic substances. The undercoat layer is formed by dissolving or dispersing the above substances in an appropriate solvent to prepare a coating solution, and then applying the coating solution to the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating. can do.
The thickness of the undercoat layer is generally in the range of 0.005 to 20 μm, preferably in the range of 0.01 to 10 μm.

Further, it is preferable that irregularities representing information such as tracking grooves or address signals are formed on the substrate (or undercoat layer). This groove is preferably formed directly on the substrate at the time of injection molding or extrusion molding of a resin material such as polycarbonate. The groove may be formed by providing a pre-groove layer. As a material for the pregroove layer, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester and tetraester and a photopolymerization initiator can be used. For the formation of the pre-groove layer, for example, first, a mixed solution composed of the above-mentioned acrylate ester and the polymerization initiator was applied on a precisely formed master (stamper), and further, a substrate was placed on this coating solution layer. Thereafter, the coating layer is cured by irradiating ultraviolet rays through the substrate or the matrix to fix the substrate and the coating layer. Next, it can be obtained by peeling the substrate from the matrix. The thickness of the pregroove layer is generally in the range of 0.05 to 100 μm, preferably in the range of 0.1 to 50 μm.

The depth of the pre-groove provided on the substrate is in the range of 300 to 2000 °, and its half-value width is in the range of 0.2 to 2000 °.
A range of 0.9 μm is preferred. By setting the depth of the pre-groove in the range of 1500 to 2000 °, sensitivity can be improved without substantially lowering the reflectivity, which is particularly preferable. Accordingly, such an optical disk (having a recording layer and a reflective layer of the dye of the general formula (I) formed on a deep pre-groove substrate) has high sensitivity, so that recording can be performed with a low laser power. Thus, there are advantages that a less expensive semiconductor laser can be used, or the service life of the semiconductor laser can be extended.

A recording layer is provided on the substrate. The recording layer is characterized by containing a benzoindolenine skeleton represented by the following general formula (I) and a novel cyanine dye of the present invention.

[0017]

Embedded image

[In the formula, R ₁ represents an alkyl group having 1 to 12 carbon atoms. The alkyl group of R ₁ has 1 to 12 carbon atoms.
May be substituted with an alkoxy group. R ₂ and R
₃ independently represents hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a halogen group. R ₄ represents hydrogen, an alkyl group having 1 to 12 carbon atoms, a halogen group, or a pyridyl group. And, X ^- is,
^{Cl -, Br -, I -} , ClO 4 -, PF 6 -, BF 4
^-, CF ₃ SO ₃ ^-, represents paratoluene sulphonate or naphthalenedisulphonic Gandolfo sulfonate. ]

R_TwoAnd R_FourIs preferably hydrogen
New X^-Is ClO_Four ^-, BF_Four ^-Or PF₆ ^-so
Preferably, there is.

A recording layer is formed on a substrate using a specific cyanine dye having a benzoindolenine skeleton represented by the above general formula (I), and a reflective layer is further provided on the recording layer. The optical disc has high reflectivity and excellent recording / reproduction characteristics such as recording sensitivity and C / N. The recording layer of a cyanine-based dye having a benzoindolenine skeleton generally has a maximum absorption wavelength on the shorter wavelength side than around 710 nm, and emits light in a wavelength band around 780 nm, which is the oscillation wavelength of laser light used for recording or reproduction. Is relatively small, and when a reflective layer is provided on the recording layer, the reflectance of the obtained optical disk is remarkably improved. That is, in a wavelength band around 780 nm, light absorption is relatively small and transmittance is high.
Since the light transmitted through the recording layer is almost reflected by the reflective layer, it is estimated that the reflectivity of the optical disk is improved.

Examples of specific compounds represented by the above general formula (I) include compound No. I-1 shown in Table 1 below.
To I-51.

[0022]

[Table 1]

[0023]

[Table 2]

The cyanine dye having a benzoindolenine skeleton represented by the general formula (I) of the present invention is disclosed in
Although it is included in the general formula of the dye used for the recording layer of the optical disk described in JP-A-40-40382 and JP-A-64-40387, there is no description of the specific structure of the present invention. For general synthesis methods and chemical behaviors of the above dyes, refer to “Chemistry of heterocyclic compounds” (The Chemistry o
f Heterocyclic Compound) series `` Cyanine Dyes and Related Compounds,
John Wiley & Sons, New York, London; 1964)
It is described in. According to the above-mentioned literature, the general formula (I)
Among the cyanine-based dyes represented by the formula (1), preferred methods are described below because their synthesis methods are not described.

Synthesis Example 1 (Synthesis of Dye I-5) First, 2,3,3-trimethyl-6-methoxybenzoindolenine was synthesized according to the method described in JP-A-9-278753. That is, 3.93 g of benzophenone hydrazone, 5.93 g of 2-bromo-6-methoxynaphthalene, 20.09 g of Pd (OAc), 2,2′-
Bis (diphenylphosphino) -1,1'-binaphthyl 0.37 g, Cs ₂ CO ₃ 9.1 g, toluene 50 m
was placed in a 100 ml three-necked flask equipped with a stirrer and a condenser, and the air in the flask was replaced with nitrogen. After heating and refluxing in an oil bath for 16 hours, the mixture was cooled and the contents were
Dried to 0 ml. The insolubles are filtered, and the filtrate is toluene 100
Extracted in ml. Magnesium sulfate was added to the extract, dried and concentrated to obtain 3.8 g of a product (yield: 54%). 1.76 g of the obtained compound, 0.2 g of 2-methyl-3-butanone.
86 g, p-toluenesulfonic acid monohydrate 2.4
g and 30 ml of ethyl alcohol were placed in a 100 ml three-necked flask equipped with a stirrer and a condenser and heated and refluxed in an oil bath for 16 hours. After cooling the reaction solution, water 100m
Then, 50 ml of concentrated hydrochloric acid was added, and the by-product was extracted three times with 50 ml of toluene. The aqueous layer was neutralized with an aqueous sodium hydroxide solution and the precipitate was filtered off to obtain 0.94 g of 2,3,3-trimethyl-6-methoxybenzoindolenine (yield 78).
%).

From the 2,3,3-trimethyl-6-methoxybenzoindolenine thus obtained, 1
-Butyl-2,3,3-trimethyl-6-methoxybenzo [e] -3H-indolium paratoluenesulfonate was obtained. The obtained 1-butyl-2,3,3-trimethyl-6-methoxybenzo [e] -3H-indolium paratoluenesulfonate (11.7 g) and malonaldehyde dianilide (2.5 g) were dissolved in acetone (60 ml) to prepare triethylamine. After dripping 2 ml, acetic anhydride 2.2m
1 was slowly added dropwise. After stirring for one hour, ion-exchanged water 12
0 ml was added dropwise and the resulting powder was filtered off. The obtained crude product is dried and dissolved in 60 ml of methanol.
4.7 g of 0% aqueous solution was added and stirred for 1 hour. The obtained crystals were filtered and dried to obtain a purified product. Yield: 8.1 g Yield: 88.9% λmax: 694.6 nm (in MeOH) ε: 2.12 × 10 ⁵

Synthesis Example 2 (Synthesis of Dye I-50) In Synthesis Example 1, instead of 1-butyl-2,3,3-trimethyl-6-methoxybenzo [e] -3H-indolium paratoluenesulfonate. 1-butyl-2,
3,3-trimethyl-6-bromobenzo [e] -3H-
Dye I-50 was obtained in the same manner as in Synthesis Example 1 except that indolium paratoluenesulfonate was used. 1-butyl-2,3,3-trimethyl-6-bromobenzoindolenine was synthesized according to the method described in JP-A-9-278753, and 1-butyl-2,3,3-trimethyl-6 was synthesized.
-Brombenzo [e] -3H-indolium paratoluenesulfonate was synthesized according to a conventional method. Yield: 80.3% λmax: 683.1 nm (in MeOH) ε: 2.44 × 10 ⁵

In the formation of the recording layer, various dyes known as a so-called singlet oxygen quencher, such as the following general formulas (II) and (III), are used to improve the light resistance together with the dye of the present invention. ) Or (IV).

[0029]

Embedded image

(Where [Cat] ⁺ represents a nonmetallic cation such as tetraalkylammonium, M represents a transition metal atom such as Ni, Z and Z ′ represent an optionally substituted benzene ring, Represents an atomic group for completing a 5- or 6-membered aromatic or hetero ring such as a thioxo-1,3-dithiol ring)

[0031]

Embedded image

[Wherein R ₅ represents an alkyl group which may have a substituent, and Q represents the same anion as that represented by X in the general formula (I)]

[0033]

Embedded image

[Wherein R ₆ represents a group having the same meaning as R _{5 in} formula (III), and Q represents an anion having the same meaning as that of formula (II)]. Or as a specific example of the quencher represented by (IV), PA-1006
(Trade name of Mitsui Toatsu Fine Co., Ltd., equivalent to general formula (II)), IRG-023, IRG-022 and IRG-
003 (these are trade names of Nippon Kayaku Co., Ltd.
II), (III) and (IV))). The amount of the quencher to be added is preferably 5 to 30 parts by weight based on 100 parts by weight of the dye of the general formula (I).

The recording layer was formed by dissolving the above-mentioned dye and, if desired, the above-mentioned quencher and binder in a solvent to prepare a coating solution, and then applying this coating solution to the substrate surface to form a coating film. Thereafter, drying can be performed. Examples of the solvent for the dye layer coating solution include esters such as ethyl acetate, butyl acetate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; dimethylformamide Hydrocarbons such as cyclohexane; ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol, n-butanol and diacetone alcohol; 2,2,3,3-tetrafluoropropanol Fluorine solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether; It can be mentioned. The above solvents can be used alone or in combination of two or more kinds in consideration of the solubility of the dye to be used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution according to the purpose.

When a binder is used, examples of the binder include natural organic high-molecular substances such as gelatin, cellulose derivatives, dextran, rosin, and rubber; and hydrocarbon-based substances such as polyethylene, polypropylene, polystyrene, and polyisobutylene. Resin, polyvinyl chloride, polyvinylidene chloride, vinyl resin such as polyvinyl chloride / polyvinyl acetate copolymer, acrylic resin such as polymethyl acrylate, polymethyl methacrylate, polyvinyl alcohol, chlorinated polyethylene, epoxy resin, Synthetic organic polymers such as butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol / formaldehyde resins can be given. When a binder is used in combination as a material for the recording layer, the ratio of the dye to the binder is generally 0.01%.
~ 99% (weight ratio), preferably 1.0 ~
95% (weight ratio). The concentration of the coating amount thus prepared is generally 0.01 to 10% (weight ratio).
And preferably in the range of 0.1 to 5% (weight ratio).

The recording layer may be a single layer or a multilayer. The thickness of the recording layer is generally in the range of 200 to 3000 °, preferably in the range of 500 to 2500 °. The recording layer may be provided not only on one side of the substrate but also on both sides. Examples of the application method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method.

On the recording layer, a reflection layer is provided for the purpose of improving the reflectance at the time of reproducing information. The light-reflective substance as the material of the reflection layer is a substance having a high reflectance to laser light, and examples thereof include Mg, Se, Y,
Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W,
Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, I
r, Pt, Cu, Ag, Au, Zn, Cd, Al, G
a, In, Si, Ge, Te, Pb, Po, Sn, Bi
Metal and semimetal or stainless steel. Of these, preferred are Cr, N
i, Pt, Cu, Ag, Au, Al and stainless steel. These substances may be used alone, or in combination of two or more kinds, or as an alloy. The reflection layer can be formed on the recording layer by, for example, vapor deposition, sputtering, or ion plating of the above-mentioned light reflective substance. The thickness of the reflective layer is generally in the range from 100 to 3000 °.

Further, a protective layer may be provided on the reflective layer for the purpose of physically and chemically protecting the recording layer and the like. This protective layer may be provided on the side of the substrate on which the recording layer is not provided for the purpose of improving the scratch resistance and the moisture resistance. Examples of the material used for the protective layer include SiO, S
Examples include inorganic substances such as iO ₂ , MgF ₂ , SnO ₂ , and Si ₃ N ₄ , and organic substances such as a thermoplastic resin, a thermosetting resin, and a UV-curable resin. The protective layer can be formed, for example, by laminating a film obtained by extrusion of a plastic on the reflective layer and / or the substrate with an adhesive layer. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating. In the case of a thermoplastic resin or a thermosetting resin, they can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying. In the case of a UV curable resin, it can also be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure. Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose. The thickness of the protective layer is generally 0.1
１００100 μm.

The information recording medium may be a single plate having the above-described configuration, or two substrates having the above-described configuration may be faced to each other such that the recording layer is on the inside, and bonded using an adhesive or the like. By doing so, a laminated type recording medium can also be manufactured. Alternatively, an air sandwich type recording medium is manufactured by joining a substrate having the above configuration to at least one of the two disk-shaped substrates via a ring-shaped inner spacer and a ring-shaped outer spacer. You can also.

An information recording medium can be manufactured by the above method. The optical disk obtained in this manner, which has an extremely high reflectance and excellent recording and reproduction characteristics,
Even if a singlet quencher is added to improve light resistance, a desired reflectance can be maintained. That is, when the quencher is added, the reflectance of the optical disk generally decreases, but the reflectance of the information recording medium is 8%.
Since it is remarkably high at about 0%, high reflectance can be maintained even when a quencher is added, and the data can be reproduced on a commercially available CD player. Accordingly, an optical disk having high reflectance and excellent light resistance can be obtained. The optical information recording method is performed using the information recording medium, for example, as follows. First, recording light such as semiconductor laser light is irradiated from the substrate side while rotating the information recording medium at a constant linear velocity (1.2 to 1.4 m / sec in the case of a CD format) or a constant angular velocity. By this light irradiation, a cavity is formed at the interface between the recording layer and the reflective layer (the cavity is formed by deforming the recording layer or the reflective layer, or by deforming both layers), or the substrate is thinned. It is considered that information is recorded when the refractive index is changed due to deformation of the recording layer or discoloration of the recording layer or a change in the association state. As the recording light, a semiconductor laser beam having an oscillation wavelength in the range of 750 to 850 nm is generally used. Reproduction of the information recorded as described above can be performed by irradiating the semiconductor laser light from the substrate side while rotating the information recording medium at the same constant linear speed as above, and detecting the reflected light. .

Hereinafter, embodiments of the present invention will be described. However, these examples do not limit the present invention.

[0043]

EXAMPLES Example 1 1.6 g of the following compound A and 0.4 g of the cyanine dye represented by the general formula (I) (the dye I-5) synthesized in Synthesis Example 1 were used in 2, 2, 3,3-tetrafluoropropanol (structural formula: HCF ₂ CF ₂ CH
₂ OH) to prepare a dye layer coating solution. Disc-shaped polycarbonate substrate provided with a tracking guide (outer diameter: 120 mm, inner diameter: 15 mm, thickness: 1.2 mm, track pitch: 1.6 μm, half width of groove: 0.5 μm, depth of groove: 650 °) )
On top, the coating solution was spin-coated at a rotational speed of 1000 r.
pm and dried for 30 seconds to achieve a layer thickness of 100
A 0 ° recording layer was formed. Au is further added to the recording layer by D
A reflective layer having a layer thickness of 1300 ° is formed by C sputtering, and a UV curable resin (trade name: 3070, trade name, manufactured by Three Bond Co.) is used as a protective layer on the reflective layer by spin coating at a speed of 1500 rpm. After applying,
Layer thickness 3μm cured by irradiating ultraviolet rays with a high pressure mercury lamp
Was formed. In this way, the substrate, the recording layer,
An information recording medium comprising a reflective layer and a protective layer was manufactured.

[0044]

Embedded image

Example 2 In Example 1, 0.4 g of the cyanine dye of Dye I-50 synthesized in Synthesis Example 2 was used instead of 0.4 g of the cyanine dye of Dye I-5. An information recording medium was manufactured in the same manner as in Example 1 except that the recording medium was used.

Example 3 In Example 1, a diimmonium dye (I) was further added to the dye layer coating solution as a quencher.
An information recording medium was manufactured in the same manner as in Example 1 except that 0.2 g of RG-023 (manufactured by Nippon Kayaku Co., Ltd.) was added to prepare a dye coating solution.

Comparative Example 1 In Example 1, a dye coating solution was prepared using 2.0 g of Compound A as a dye, and an information recording medium was produced in the same manner as in Example 1.

The characteristics of the information recording media obtained in the above Examples and Comparative Examples were evaluated as follows.

1) C / N The information recording medium obtained above is irradiated with a semiconductor laser beam having a wavelength of 780 nm through an objective lens having an NA of 0.5 to focus on the recording layer of the medium and to track the groove in the groove. While the linear velocity was 5.2 m / sec and the recording power was 7.0 mW
, Modulation frequency 720 kHz (duty 33%)
Was recorded. And the recorded signal is 0.5 mW
And the C / N at the time of reproduction is measured with a spectrum analyzer (TR4135: manufactured by Advantest)
It measured using.

2) Reflectivity When tracking into an unrecorded groove with a reproduction power of 0.5 mW using the same optical system (apparatus) as in 1), the amount of reflected light (X) returning from the medium is measured by a photodetector. Was measured. Next, the medium was removed, and a photodetector was placed at a position where the medium was located, and the amount of incident light (Y) was measured. Then, (X / Y) × 100 (%) was defined as the reflectance.

3) Sensitivity 4.5 to 7.0 using the same optical system (apparatus) as in 1).
CD format EFM at a constant linear speed of 5.2 m / sec (4 times speed) while changing the recording power in 0.5 mW increments up to 0.5 mW
The signal was recorded. The recorded signal was reproduced with a reproduction power of 0.5 mW, and the number of C1 error frames generated per second was measured. The smallest recording power at which the number of C1 error frames was less than 30 was defined as the sensitivity. Table 3 shows the evaluation results of the dye-coated products obtained in the above Examples and Comparative Examples.

[0052]

[Table 3]

As is clear from Table 3, the information recording media having a specific cyanine dye recording layer of the present invention (Examples 1 to 3) have high sensitivity and a high level of C / N. I have.

[0054]

According to the present invention, a recording layer made of a specific cyanine dye having a benzoindolenine skeleton represented by the above general formula (I) is provided on a substrate, and a reflective layer made of a metal is laminated on the recording layer. The optical disk according to the present invention has a C /
Not only are the recording and reproduction characteristics such as N and the degree of modulation excellent, but also the sensitivity is high. In addition, the optical disk using the specific cyanine dye of the present invention has a remarkably high reflectance, so that even if a quencher or the like, which easily lowers the reflectance of the recording layer, is added in order to improve light resistance, a high level is obtained. The reflectance can be maintained. Therefore, it is possible to obtain an optical disk having excellent light resistance and high reflectance. Furthermore, the resulting optical disc has a remarkably high sensitivity,
Since the EFM signal of the format can be recorded and reproduced by a commercially available CD player, it is useful as a CD-DRAW.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuyoshi Yamakawa 210 No. Nakanuma, Minamiashigara-shi, Kanagawa Prefecture F-term in Fuji Photo Film Co., Ltd. (Reference) 2H111 EA03 EA12 EA22 EA25 EA33 EA37 EA39 FA01 FA12 FB43 4H056 CA02 CC08 CE03 DD03 FA06 5D029 JA04 JC20

Claims (4)

[Claims] 1. The following general formula (I): [In the formula, R ₁ represents an alkyl group having 1 to 12 carbon atoms. The alkyl group for R ₁ may be substituted with an alkoxy group having 1 to 12 carbon atoms. R ₂ and R ₃ each independently represent hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or a halogen group. R ₄
Represents hydrogen, an alkyl group having 1 to 12 carbon atoms, a halogen group, or a pyridyl group. Then, X ^- is, Cl ^-, Br
^{_{-, I -, ClO 4 -}} , PF 6 -, BF 4 -, CF 3 S
O ₃ ⁻ , represents paratoluenesulfonate or naphthalenedisulfonate. And a cyanine-based dye having a benzoindolenine skeleton. 2. The cyanine dye according to claim 1, wherein R ₂ is hydrogen in the general formula (I). 3. The cyanine dye according to claim 1, wherein R ₃ is hydrogen in the general formula (I). 4. An information recording medium using the cyanine dye according to claim 1 as a recording material for a recording layer of an information recording medium having a recording layer and a reflective layer thereon.