JP2827005B2 - Cyanine dye - Google Patents

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 a disk-shaped substrate made of glass, synthetic resin, or the like, and a Bi, S provided thereon.
a recording layer comprising a metal or semimetal such as n, In, Te or the like; or a dye such as a cyanine-based, metal complex-based, or quinone-based dye. 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 reflectivity, it is common practice to further provide a reflective layer on the dye recording layer.
One such example is Nikkei Electronics (page 107, 1
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 accordingly, the plastic substrate is heated and the substrate rises to the recording layer side to form pits. This reflection layer is a deposited film of gold. And EP
Japanese Patent Publication No. 0353393 discloses that a cyanine dye having a benzoindolenine skeleton is used for a 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 disk, 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. The recorded signal is
Playback on a D player is required. 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%) be used as a DRAW.

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.

The present invention provides a compound represented by the following general formula (I):

[0010]

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[Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ each independently represent a methyl group or an ethyl group, Y represents a methyl group or a benzyl group, and, X ^- is, ClO ₄ ^- or PF
₆ ^- represents a. And a cyanine-based dye having a benzoindolenine skeleton.

Preferred embodiments of the above-mentioned cyanine dyes are as follows. 1) The above cyanine-based dye, wherein R ² and R ³ represent a methyl group. 2) Y is the above cyanine-based dye representing a methyl group.

[0013]

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). 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 use of a cyanine-based dye having a benzoindolenine skeleton represented by the above general formula (I) as a recording layer makes it possible to realize the above. 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. In many cases, it has been found that, in a wavelength band around 780 nm, which is the oscillation wavelength of general laser light, the reflectance is high, and the C / N and the degree of modulation are 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 pregroove provided on the substrate is in the range of 300 to 2000 °, and the half width thereof 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 in that the benzoindolenine skeleton represented by the following general formula (I) contains the novel cyanine dye of the present invention.

[0019]

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[Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ each independently represent a methyl group or an ethyl group, and Y represents a methyl group or a benzyl group. and, X ^- is, ClO ₄ ^- or
PF ₆ ^- represents a. ]

R ² and R ³ are preferably a methyl group. Y is preferably a methyl group.

An optical disk of the present invention in which 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 reflection layer is further provided on the recording layer. Shows high reflectance and
The recording / reproducing characteristics such as recording sensitivity and C / N are also excellent. The recording layer of the cyanine-based dye having the benzoindolenine skeleton generally has a maximum absorption wavelength of 710 nm.
In a wavelength band around 780 nm, which is an oscillation wavelength of laser light used for recording or reproduction, which has a shorter wavelength side than the vicinity, light absorption is relatively small, and is obtained when a reflective layer is provided on the recording layer. It has the characteristic that the reflectivity of the optical disk is significantly improved. That is, in the wavelength band around 780 nm, light absorption is relatively small and the transmittance is high, and light transmitted through the recording layer is almost reflected by the reflection layer. Therefore, it is estimated that the reflectance of the optical disk is improved.

Examples of specific compounds represented by the above general formula (I) include the following I-1 to I-17.

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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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 in the recording layer of the optical disk described in JP-A-4-40382 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 Chemistr
y of Heterocyclic Compound) series “Cyanine Dyes and Related Com”
pound, John Wiley & Sons, New York, London; 1964). Preferred literatures among the cyanine-based dyes represented by the general formula (I) of the present invention are not described in the above-mentioned documents, and their synthesis methods are not described.

Synthesis Example 1 (Synthesis of Dye I-1) 150 ml of pyridine was added to 40 g of 1,2,3,3-tetramethylbenzo [e] -3H-indolium paratoluenesulfonate, and 1,1 was heated under reflux. 37 g of 3,3,3-tetraethoxy-2-methylpropane were added dropwise. Then, after heating under reflux for 1 hour, the solvent was distilled off under reduced pressure, and 500 ml of methanol was added to the residue. After filtering the insoluble matter, 20 ml of a 60% aqueous solution of perchloric acid was added while stirring under ice cooling. The resulting crystals were collected by filtration to obtain 30 g of crude crystals of the dye I-1. After dissolving this in chloroform, it was diluted with methanol, and chloroform and methanol were distilled off to obtain crystals of Dye I-1. Yield: 25.5 g Melting point: 187-189 ° C

Synthesis Example 2 (Synthesis of Dye I-2) In Synthesis Example 1, 1,1,3,3-tetraethoxy-
Dye I-2 was obtained in the same manner as in Synthesis Example 1 except that 1,1,3,3-tetraethoxy-2-benzylpropane was used instead of 2-methylpropane. Melting point: 246-248 ° C

Synthesis Example 3 (Synthesis of Dye I-5) In Synthesis Example 1, 1-ethyl-2,1-ethyl-2,3-tetramethylbenzo [e] -3H-indolium Dye I-5 was obtained in the same manner as in Synthesis Example 1, except that 3,3-trimethylbenzo [e] -3H-indolium paratoluenesulfonate was used. Melting point: 221-233 ° C

Synthesis Example 4 (Synthesis of Dye I-6) In Synthesis Example 1, instead of 1,2,3,3-tetramethylbenzo [e] -3H-indolium paratoluenesulfonate, 1-propyl-2, Dye I-6 was obtained in the same manner as in Synthesis Example 1 except that 3,3-trimethylbenzo [e] -3H-indolium paratoluenesulfonate was used. Melting point: 230-234 ° C

Synthesis Example 5 (Synthesis of Dye I-7) In Synthesis Example 1, 1-butyl-2,2,3-tetramethylbenzo [e] -3H-indolium was used instead of paratoluenesulfonate. Dye I-7 was obtained in the same manner as in Synthesis Example 1 except that 3,3-trimethylbenzo [e] -3H-indolium iodide was used, and a small amount of ethanol was added in addition to pyridine as a solvent, followed by heating under reflux. I got Melting point: 198-199 ° C

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 in order to improve light resistance together with the dye of the present invention. ) Or (IV) is preferably used in combination.

[0036]

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(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)

[0038]

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

[0040]

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[In the formula, R represents a group having the same meaning as in the general formula (III), and Q represents an anion having the same meaning as the general formula (II).] In the above general formula (II), (III) or (IV), Specific examples of the quencher represented include PA-1006 (Mitsui Toatsu Fine Co., Ltd.), IRG-023, and IRG-02.
2 and IRG-003 (Nippon Kayaku Co., Ltd.) and the like. 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 reflective layer is provided for the purpose of improving the reflectivity during information reproduction. 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 may be used 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 it is in the range of 100-3000 °.

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. Also,
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-mentioned 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 lamination 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 method as described above. 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 formed. It is considered that information is recorded when the recording layer is deformed or the refractive index changes due to discoloration or change in the association state of the recording layer. As the recording light, a semiconductor laser beam having an oscillation wavelength in the range of 750 nm 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.

[0050]

【Example】

Example 1 2.0 g of a cyanine dye represented by the general formula (I) (the dye I-1) was added to 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, groove half width: 0.5 μm, groove depth: 900 mm) )
On top, the coating solution was spin-coated at a rotational speed of 1000 r.
pm and dried for 30 seconds to give a layer thickness of 200
A 0 ° recording layer was formed. Au is further added to the recording layer by D
A reflective layer having a thickness of 1300 ° was formed by C sputtering, and a UV-curable resin (trade name: 3070, manufactured by Three Bond Co.) was applied as a protective layer on the reflective layer by a spin coating method at a rotation speed of 1500 rpm. Thereafter, a protective layer having a layer thickness of 3 μm was formed by irradiating ultraviolet rays with a high-pressure mercury lamp to cure the layer. Thus, an information recording medium including the substrate, the recording layer, the reflective layer, and the protective layer was manufactured.

Example 2 The procedure of Example 1 was repeated, except that 2.0 g of the cyanine dye of the dye I-2 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in Example 1.

Example 3 The procedure of Example 1 was repeated except that 2.0 g of the cyanine dye I-5 was used instead of 2.0 g of the cyanine dye I-1. An information recording medium was manufactured in the same manner as in Example 1.

Example 4 The procedure of Example 1 was repeated, except that 2.0 g of the cyanine dye of the dye I-6 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in Example 1.

Example 5 The procedure of Example 1 was repeated, except that 2.0 g of the cyanine dye of the dye I-7 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in Example 1.

Example 6 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.

Example 7 The procedure of Example 6 was repeated, except that 2.0 g of the cyanine dye of the dye I-2 was used instead of 2.0 g of the cyanine dye of the dye I-1. In the same manner as in No. 6, an information recording medium was manufactured.

Example 8 The procedure of Example 6 was repeated, except that 2.0 g of the cyanine dye of the dye I-5 was used instead of 2.0 g of the cyanine dye of the dye I-1. In the same manner as in No. 6, an information recording medium was manufactured.

Example 9 The procedure of Example 6 was repeated except that 2.0 g of the cyanine dye of the dye I-6 was used instead of 2.0 g of the cyanine dye of the dye I-1. In the same manner as in No. 6, an information recording medium was manufactured.

Example 10 The procedure of Example 6 was repeated, except that 2.0 g of the cyanine dye I-7 was used instead of 2.0 g of the cyanine dye I-1. In the same manner as in No. 6, an information recording medium was manufactured.

Example 11 An information recording medium was manufactured in the same manner as in Example 6, except that a substrate having a groove depth of 1600 ° was used instead of the substrate having a groove depth of 900 °. did.

Example 12 The procedure of Example 11 was repeated, except that 2.0 g of the cyanine dye of the dye I-2 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in No. 11.

Example 13 The procedure of Example 11 was repeated except that 2.0 g of the cyanine dye I-5 was used instead of 2.0 g of the cyanine dye I-1. An information recording medium was manufactured in the same manner as in No. 11.

Example 14 The procedure of Example 11 was repeated, except that 2.0 g of the cyanine dye of the dye I-6 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in No. 11.

Example 15 The procedure of Example 11 was repeated, except that 2.0 g of the cyanine dye of the dye I-7 was used instead of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in No. 11.

Example 16 In Example 1, a substrate having a groove depth of 400 ° was used instead of the substrate having a groove depth of 900 °, and the solvent of the dye layer coating solution was 2,2.
An information recording medium was manufactured in the same manner as in Example 1, except that 100 cc of 2,3,3-tetrafluoropropanol was changed to 90 cc of 2,2,3,3-tetrafluoropropanol and 10 cc of propylene glycol monomethyl ether.

[Comparative Example 1] A dye coating solution was prepared in the same manner as in Example 1 except that the following dye A was used in place of 2.0 g of the cyanine dye of the dye I-1. An information recording medium was manufactured in the same manner as in Example 1 except that 2000 ° was changed to 1300 °. Dye A

[0067]

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[Comparative Example 2] The diimmonium dye (IR) was added to the dye layer coating solution of Comparative Example 1 as a quencher.
G-023, manufactured by Nippon Kayaku Co., Ltd.), and an information recording medium was manufactured in the same manner as in Comparative Example 1, except that 0.2 g of a dye layer coating solution was prepared.

Comparative Example 3 An information recording medium was manufactured in the same manner as in Comparative Example 1, except that 2.0 g of the following dye B was used instead of 2.0 g of the dye A to prepare a dye coating solution. did. Dye B

[0070]

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Comparative Example 4 An information recording medium was manufactured in the same manner as in Comparative Example 1, except that the thickness of the recording layer was changed from 1300 ° to 2000 °.

Comparative Example 5 An information recording medium was manufactured in the same manner as in Comparative Example 2, except that the thickness of the recording layer was changed from 1300 ° to 2000 °.

Comparative Example 6 An information recording medium was manufactured in the same manner as in Comparative Example 3, except that the thickness of the recording layer was changed from 1300 ° to 2000 °.

Comparative Example 7 An information recording medium was manufactured in the same manner as in Comparative Example 4, except that the groove depth of the substrate was changed from 900 ° to 1600 °.

Comparative Example 8 An information recording medium was manufactured in the same manner as in Comparative Example 5, except that the groove depth of the substrate was changed from 900 ° to 1600 °.

Comparative Example 9 An information recording medium was manufactured in the same manner as in Comparative Example 6, except that the groove depth of the substrate was changed from 900 ° to 1600 °.

Comparative Example 10 The procedure of Example 16 was repeated, except that 2.0 g of the dye A was used instead of 2.0 g of the cyanine dye of the dye I-1 to prepare a dye coating solution. To manufacture an information recording medium.

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. At a constant linear velocity of 1.3 m / sec and a recording power of 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) Reflectance The amount of reflected light (X) returning from the medium was measured with a photodetector when tracking was performed in an unrecorded groove with a reproduction power of 0.5 mW using the same optical system (apparatus) as in 1). . Next, the medium was removed, and the same photodetector was placed at a position in the medium, 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).
The CD format EFM signal was recorded at a constant linear velocity of 1.3 m / sec while changing the recording power by 0.5 mW in increments of mW. 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 1 shows the compositions of the dye layer coating liquids obtained in the above Examples and Comparative Examples and the above measurement results.

[0080]

[Table 1] Table 1 ──────────────────────────────────── Material name Layer thickness Groove depth Sensitivity Reflectance C / N Dye / quencher (Å) (Å) (mW) (%) (dB) ───────────────────────── ─────────── Example 1 1 / −− 2000 900 6 81 52 Example 2 2 / −− 2000 900 6 82 50 Example 3 5 / −− 2000 900 6 81 50 Example 4 6 / −2000 900 6 80 51 Example 5 7 / −− 2000 900 6 81 50 Example 6 1 / IRG023 2000 900 6 79 52 Example 7 2 / IRG023 2000 900 6 80 50 Example 8 5 / IRG023 2000 900 6 79 51 Example 9 6 / IRG023 2000 900 6 78 51 Example 10 7 / IRG023 2000 900 6 7951 Example 11 1 / IRG023 2000 1600 5 78 52 Example 12 2 / IRG023 2000 1600 5 79 50 Example 13 5 / IRG023 2000 1600 5 78 51 Example 14 6 / IRG023 2000 1600 5 78 50 Example 15 7 / IRG023 2000 1600 5 78 50 Example 16 1 / −− 2000 400 6 80 50 ─────────────────────────────────── ─ Comparative Example 1 A / −− 1300 900 6 73 50 Comparative Example 2 A / IRG023 1300 900 6 69 50 Comparative Example 3 B / −− 1300 900 6 73 50 Comparative Example 4 A / −− 2000 900 6 72 50 Comparative Example 5 A / IRG023 2000 900 6 68 49 Comparative Example 6 B / −− 2000 900 6 71 49 Comparative Example 7 A / −− 2000 1600 5.5 69 50 Comparative Example 8 A / IRG023 2000 1600 5.5 68 50 Comparative Example 9 B / − − 2000 1600 5.5 68 50 Comparative Example 10 A / −− 2000 400 6 70 49 ──────────────────────────────── ────

As is clear from Table 1, the information recording media having a specific cyanine dye recording layer of the present invention (Examples 1 to 16) have remarkably high reflectance and high C / N. Indicates the level. Therefore, even when a quencher was added to improve light resistance, Examples 6 to 1 were used.
5, high reflectivity can be maintained. Examples 11 to 1 using a substrate having a deep groove were used.
It can be seen that the optical disk No. 5 has further excellent recording sensitivity. On the other hand, optical disks (Comparative Examples 1 and 3) using dyes A and B having a benzoindolenine skeleton, which are generally known for their high reflectivity and excellent recording / reproducing characteristics, were compared with Examples. Then, the reflectance is low, and it cannot be said that the reflectance is sufficiently satisfactory for reproducing information with a CD player. Further, when a quencher was added to improve the light resistance (Comparative Example 2), the result was that the reflectance was lower than 70%. The optical disks of Comparative Examples 7 to 9 using a substrate having a deep groove have slightly higher sensitivity, but are inferior in both sensitivity and reflectivity to those of Examples 11 to 15 described above.

[0082]

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 of the present invention has a C /
Not only are recording and reproducing characteristics such as N and modulation degree excellent, but also the reflectivity is remarkably high. Further, since the optical disc of the present invention has a remarkably high reflectance, it is possible to maintain a high level of reflectance even when a quencher or the like that easily lowers the reflectance of the recording layer is added in order to improve light resistance. it can. Therefore, it is possible to obtain an optical disk having excellent light resistance and high reflectance. In addition, in particular, as described above,
When the dye layer of the present invention and the reflective layer are provided thereon on a substrate having a pregroove having a deep groove of 500 to 2000 °, the sensitivity can be improved without substantially lowering the reflectance. Furthermore, since the obtained optical disk has a remarkably high reflectance, it can be used as a CD-DRAW because an EFM signal in a CD format can be recorded and reproduced by a commercially available CD player.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Kubo 210 Nakanuma, Minamiashigara-shi, Kanagawa Fujisha Shin Film Co., Ltd. (56) References Kvantovaya Elektron. (Moscow), 6 (1), p31-7, 1979 (58) Fields investigated (Int. Cl. ⁶ , DB name) C09B 23/00 CA (STN)

Claims (3)

(57) [Claims] 1. The following general formula (I): [Wherein, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ each independently represent a methyl group or an ethyl group, Y represents a methyl group or a benzyl group, and X ^- is, ClO ₄ ^- or PF ₆ ^- represent. And a cyanine dye having a benzoindolenine skeleton. 2. In the general formula (I), R ² and R ³
It represents a methyl group, Y Wath Table methyl claim 1
3. The cyanine dye according to item 1. 3. The following chemical structural formula: Embedded image A cyanine dye represented by any one of the above.