JP2992164B2 - Information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium provided with a recording layer made of a dye to which information can be written by a laser.

[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. A general write-once type (DRAW type) information recording medium has a disc-shaped transparent substrate made of plastic, glass or the like as a basic structure, and Bi, S provided thereon.
and a recording layer made of a metal or semimetal such as n, In, or Te. Writing of information on the recording medium is performed, for example, by irradiating the recording medium with a laser beam, and the irradiated portion of the recording layer absorbs the light and locally rises in temperature, resulting in physical changes such as pit formation. Alternatively, information is recorded by causing a chemical change such as a phase change to change its optical characteristics. Reading of information from the optical disk is also performed by irradiating the optical disk with a laser beam, and the information is reproduced by detecting reflected light or transmitted light corresponding to a change in the optical characteristics of the recording layer.

When the above-mentioned low melting point metal or metalloid is used as the recording layer, there are drawbacks such as insufficient recording sensitivity and storage stability, and high production cost. In recent years, it has been proposed and practiced to use a dye layer whose physical properties can be changed by light having a relatively long wavelength for the recording layer. As a laser beam used for recording and reproducing information from such a recording layer, a semiconductor laser is generally used. The wavelength of the laser light emitted by the semiconductor laser is in the near infrared region or a wavelength region in the vicinity thereof (700 to 900 nm).
Exists.

As a typical example of such a dye having an absorption region on the long wavelength side, a cyanine dye is well known. In general, a cyanine dye easily absorbs light near the near infrared region and has excellent recording / reproducing characteristics such as C / N.
The reflectivity cannot be said to be sufficiently high as 30 to 40%, which hinders expansion of applications and further improvement of characteristics.

Among cyanine dyes, imidazo [4,5-
b] Cyanine compounds having a quinoxaline skeleton have attracted attention because of their particularly high reflectance when used in the recording layer of an optical disc. Optical discs using such compounds for the recording layer are disclosed in JP-A-2-572 and JP-A-2-8.
No. 9683, and the like. An information recording medium in which such a cyanine compound having an imidazo [4,5-b] quinoxaline ring is formed on a substrate generally shows good recording / reproducing characteristics, and further employs a production method such as forming an association state. By selecting it, the reflectance for light having a wavelength around 780 mm to 830 mm is 60%.
It can be set to a remarkably high value as described above. By setting the reflectivity to be high as described above, reading can be performed even when the output of the laser is low at the time of reproduction, so that it can be easily applied to various drives and read durability is improved.

However, in the information recording medium having a high reflectance as described above, the state of the dye recording layer to be formed is liable to fluctuate depending on coating conditions and other working conditions, so that an optical disk having a high reflectance has a high yield. In addition, there is a problem that it is difficult to manufacture an optical disc having excellent storage stability because the obtained recording layer is easily deteriorated with time.

According to the study of the present inventors, among such cyanine dyes, according to the study of the present inventors, the cyanine dye has five methine chains, and a six-membered ring formed by a trimethylene bridging group at positions 2 and 4 of the methine chain. And a cyanine dye in which the 2-position of the 6-membered ring is substituted with two substituents (see JP-A-2-134290) does not have an imidazole ring, but has a relatively high reflection when used as a recording layer. Rate. However, it has been clarified that it is difficult to stably produce such an optical disk even when a dye exhibiting a high reflectance does not have sufficient other properties or a high reflectance can be obtained.

[0008]

As a result of further studies by the present inventors, a cyanine dye represented by the following general formula (I) in which the 2-position of the above 6-membered ring is substituted by only one alkyl group or aryl group is described. It has been clarified that the use of the recording layer makes it possible to obtain an optical disk excellent not only in reflectivity but also in productivity. The reason is as described in 6 above.
Since only one of the 2-positions of the member ring is substituted, the dye is asymmetric at the center of the molecule, so that when the dye layer is formed, the dye is likely to be stably aggregated, whereby a high reflectance can be obtained. Guessed. In addition, the stability of characteristics when mass-produced is assured or more than that of conventional cyanine dyes.

Accordingly, the present invention provides an information having a dye recording layer having high reflectance and excellent recording / reproducing characteristics and having improved production stability such that such a high quality product can be produced stably. It is intended to provide a recording medium.

[0010]

An object of the present invention is to provide an information recording medium in which a recording layer made of a dye on which information can be written by a laser beam is provided on a substrate.
The following general formula (I):

[0011]

Embedded image Wherein R ¹ represents an alkyl group, an aryl group or a heterocyclic group; Q ¹ and Q ² represent a methylene group;
L ¹ , L ² , L ³ , L ⁴ and L ⁵ represent a methine group, n represents 0 or 1, m represents 0 or 1, and Z ¹ represents N ⁺ = (L ² − L ³⁾ _n = represents an atomic group necessary for forming a nitrogen-containing heterocyclic 5- or 6-membered with C, Z ²
Represents an atomic group necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring together with C = (L ⁴ -L ⁵ ) _m = N, and R ² and R ³
Represents an alkyl group, X represents a charge neutralizing counter ion, and p represents a positive number necessary for X to neutralize the charge in the molecule, provided that X is a neutralizing charge in the molecule. This can be achieved by an information recording medium comprising a cyanine dye represented by the formula:

Preferred embodiments of the information recording medium of the present invention are as follows. 1) The information recording medium as described above, wherein R ¹ represents an alkyl group having 1 to 3 carbon atoms, a phenyl group or a naphthyl group.

2) The information recording medium as described above, wherein Q ¹ and Q ² each represent an unsubstituted methylene group.

3) L ¹ , L ² , L ³ , L ⁴ and L ⁵ are
The above information recording medium, which represents an unsubstituted methine group.

4) Z ¹ represents an atomic group necessary for forming a benzothiazole ring, a naphthothiazole ring, a benzoxazole ring or a naphthoxazole ring together with N ⁺ = (L ² -L ³ ) _n = C. The above-mentioned information recording medium characterized by the above-mentioned.

5) Z ² represents an atomic group necessary for forming a benzothiazole ring, a naphthothiazole ring, a benzoxazole ring or a naphthoxazole ring together with C = (L ⁴ -L ⁵ ) _m = N. The above information recording medium characterized by the above-mentioned.

6) The information recording medium as described above, wherein R ² and R ³ represent an alkyl group having 1 to 5 carbon atoms.

7) The above cyanine dye is represented by the following general formula (II):

[0019]

Embedded image [However, R ¹ , R ² and R ³ have the same meanings as in the above general formula (I), and W ¹ and W ² represent -S- and -O, respectively.
— Or —Se—, Z ³ and Z ⁴ each represent a hydrogen atom, a chlorine atom, a benzene ring or a naphthalene ring which may be substituted with a methyl group, a methoxy group or a propoxy group, and these substituents are May form a dioxolane, and X ₁ represents a charge neutralizing counter ion].

[Detailed Description of the Invention] The information recording medium of the present invention has a basic structure in which a dye recording layer on which information can be written by a laser is provided on a substrate.

The information recording medium of the present invention can be manufactured, for example, by the following method. The substrate used in the present invention can be arbitrarily selected from various materials used as a substrate of a conventional information recording medium. Examples of the substrate material include glass such as soda-lime glass; acrylic resin such as polymethyl methacrylate; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer; epoxy resin; and polycarbonate. Among these, polymethyl methacrylate, polycarbonate, epoxy resin and glass are preferable from the viewpoints of dimensional stability, transparency and flatness.

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 for the undercoat layer include high molecular substances such as polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, nitrocellulose, polyethylene, polypropylene, and polycarbonate; organic substances such as silane coupling agents; and inorganic oxides. (SiO ₂ , Al ₂ O _3, etc.) and inorganic fluorides (MgF ₂ ). In the case of a glass substrate, a hydrophilic group such as a styrene / maleic anhydride copolymer and / or maleic anhydride is used in order to prevent the recording layer from being adversely affected by alkali metal ions and alkaline earth metal ions released from the substrate. It is desirable that an undercoat layer made of a polymer having a group be provided. The undercoat layer can be formed, for example, by dissolving or dispersing the above substance in an appropriate solvent, and then applying this coating solution to the substrate surface by a coating method such as spin coating, dip coating, or extrusion coating.

A pre-groove layer may be provided on the substrate for the purpose of forming irregularities representing information such as tracking grooves or address signals. As the material of the pregroove layer, acrylic acid monoester, diester,
A mixture of at least one monomer (or oligomer) of a triester and a tetraester and a photopolymerization initiator can be used. The pre-groove layer is formed by first applying a mixed solution composed of the above-mentioned acrylate and a polymerization initiator on a precisely formed master (stamper), and then placing a substrate on the coating solution layer. The liquid layer is cured by irradiating ultraviolet rays through the substrate or the matrix to fix the substrate and the liquid phase. Next, the substrate provided with the pre-groove layer is obtained by peeling the substrate from the matrix. The thickness of the pre-groove layer is generally 0.0
In the range of 5-100 μm, preferably 0.1-50
in the range of μm. In the case of a plastic substrate, a pre-groove may be provided directly on the substrate surface at the time of molding the substrate.

The information recording medium of the present invention may be provided on a substrate (optionally via an undercoat layer and / or a pre-groove layer).
An intermediate layer may be provided. The formation of the intermediate layer on the substrate surface can be performed by a known coating method. Examples of known coating methods include a spin coating method and a dip coating method. In addition, examples of the intermediate layer formed by the coating method include an adhesive layer, a heat insulating layer, a reflective layer,
A sensitivity enhancement layer (gas generation layer) and the like can be mentioned.
When the intermediate layer is a heat insulating layer, for example, polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide copolymer, styrene sulfonic acid copolymer Copolymer, styrene / vinyl toluene copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, polyethylene, polypropylene, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer And a polymer such as polycarbonate, and a coating solution in which a polymer such as a silane coupling agent is dissolved in a solvent. Alternatively, the intermediate layer may be formed by performing vapor deposition such as sputtering on a fluororesin such as polytetrafluoroethylene. Preferably, it is an intermediate layer made of chlorinated polyethylene or fluororesin. As a result, it is possible to reduce the loss of thermal energy due to laser beam irradiation due to heat conduction from the recording layer to the substrate, etc., and it is easy to form pits by generating gas from the irradiated portion of the intermediate layer, Therefore, it is possible to increase the recording sensitivity and reduce the reading error (bit error rate). The thickness of the intermediate layer is
Generally, it is in the range of 1 to 100 nm, preferably 10 to 100 nm.
It is in the range of 50 nm.

On the above-mentioned substrate (optionally on the undercoat layer, pre-groove layer and / or intermediate layer), a recording layer comprising the dye of the following general formula (I) of the present invention is provided. General formula (I):

[0026]

Embedded image Wherein R ¹ represents an alkyl group, an aryl group or a heterocyclic group; Q ¹ and Q ² represent a methylene group;
L ¹ , L ² , L ³ , L ⁴ and L ⁵ represent a methine group, and Z ¹ forms a 5- or 6-membered nitrogen-containing heterocyclic ring with N ⁺ = (L ² -L ³ ) _n = C It represents an atomic group necessary for, Z ²
Represents an atomic group necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring together with C = (L ⁴ -L ⁵ ) _m = N, and R ² and R ³
Represents an alkyl group; n represents 0 or 1;
Represents 0 or 1, X represents a charge neutralizing counter ion, and p represents a positive integer necessary for X to neutralize the charge in the molecule (provided that neutralization in the molecule is excluded). When there is no charge to be represented, 0)]

The alkyl group for R ¹ generally has 1 carbon atom.
To 18 alkyl groups, preferably an alkyl group having 1 to 7 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. Examples of unsubstituted alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, octyl, dodecyl, and octadecyl. Examples of the substituted alkyl group include an aralkyl group (eg, a benzyl group,
2-phenylethyl group), hydroxyalkyl group (eg,
2-hydroxyethyl group, 3-hydroxypropyl group), carboxyalkyl group (eg, 2-carboxyethyl group, 3-carboxypropyl group, 4-carboxybutyl group, carboxymethyl group), alkoxyalkyl group (eg, 2- Methoxyethyl group, 2- (2-methoxyethoxy) ethyl group), sulfoalkyl group (eg, 2-sulfoethyl group, 3-sulfopropyl group, 3-sulfobutyl group, 4-sulfobutyl group, 2- [3-sulfopropoxy) ] Ethyl group, 2-hydroxy-3-sulfopropyl group, 3-sulfopropoxyethoxyethyl group), sulfatoalkyl group (eg, 3-sulfatopropyl group, 4-
Sulfatobutyl group), heterocyclic-substituted alkyl group (eg, 2
-(Pyrrolidin-2-one-1-yl) ethyl group, tetrahydrofurfuryl group, 2-morpholinoethyl group), 2
-Acetoxyethyl group, carbomethoxymethyl group, 2-
Mention may be made of methanesulfonylaminoethyl and allyl groups.

Examples of the unsubstituted aryl group include a phenyl group, a 2-naphthyl group and a 1-naphthyl group. Examples of the substituted aryl group include a 4-carboxyphenyl group, a 4-sulfophenyl group, a 3-chlorophenyl group, and a 3-methylphenyl group.

Examples of the unsubstituted heterocyclic group include a 2-pyridyl group, a 2-thiazolyl group, a 2-furyl group and a 2-thiophenyl group. Examples of the substituted heterocyclic group include a 4-methyl-2-pyridyl group and a 4-phenyl-2-thiazolyl group.

R ¹ is an alkyl group having 1 to 3 carbon atoms,
It is preferably a phenyl group or a naphthyl group.

Q ¹ and Q ² are an unsubstituted methylene group or a substituted methylene group. Examples of the substituent of the substituted methylene group include a carboxy group, a sulfo group, a cyano group, a halogen atom (eg, a fluorine atom, a chlorine atom, and a bromine atom), a hydroxy group, and an alkoxycarbonyl group having 8 or less carbon atoms (eg,
Methoxycarbonyl group, ethoxycarbonyl group, phenoxycarbonyl group, benzyloxycarbonyl group), alkoxy group having 8 or less carbon atoms (eg, methoxy group, ethoxy group, benzyloxycarbonyl group), 1 carbon atom
5 or less monocyclic aryloxy groups (eg, phenoxy group,
p-tolyloxy group), acyloxy group having 8 or less carbon atoms (acetyloxy group, propionyloxy group), acyl group having 8 or less carbon atoms (acetyl group, propionyl group, benzoyl group), carbamoyl group (eg, carbamoyl group) , N, N-dimethylcarbamoyl group, morpholinocarbonyl group, piperidinocarbonyl group), sulfamoyl group (eg, sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfonyl group, piperidinosulfonyl group) and carbon An aryl group having 15 or less atoms (eg,
Phenyl group, 4-chlorophenyl group, and 4-methylphenyl group). Q ¹ and Q ² are preferably an unsubstituted methylene group.

L ¹ , L ² , L ³ , L ⁴ and L ⁵ represent an unsubstituted methine group or a substituted methine group. Examples of the substituent of the substituted methine group include a substituted or unsubstituted alkyl group (eg, methyl group, ethyl group, 2-carboxyethyl group) and a substituted or unsubstituted aryl group (eg, phenyl group, o-carboxyphenyl group) ), Halogen atoms (eg,
Chlorine atom, bromine atom), alkoxy group (eg, methoxy group, ethoxy group), amino group (N, N-diphenylamino group, N-methyl-N-phenylamino group, N-methylpiperazino group). L ¹ , L ² , L
³ , L ⁴ and L ⁵ are preferably an unsubstituted methine group or a methyl-substituted methine group.

Z ¹ is formed with N ⁺ = (L ² -L ³ ) _n = C and a 5- or 6-membered nitrogen-containing heterocycle and Z ² is formed with C = (L ⁴ -L ⁵ ) _m = N Examples of the 5- or 6-membered nitrogen-containing heterocyclic ring include the following. Thiazole ring ｛thiazole ring (eg,
Thiazole, 4-methylthiazole, 4-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole), benzothiazole ring (eg, benzothiazole, 4-chlorobenzothiazole, 5-chlorobenzothiazole, 6- Chlorobenzothiazole, 5-nitrobenzothiazole, 4-methylbenzothiazole,
5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 5-iodobenzothiazole, 5-phenylbenzothiazole, 5-methoxybenzothiazole,
6-methoxybenzothiazole, 5-ethoxybenzothiazole, 5-ethoxycarbonylbenzothiazole,
5-carboxybenzothiazole, 5-phenethylbenzothiazole, 5-fluorobenzothiazole, 5-chloro-6-methylbenzothiazole, 5,6-dimethylbenzothiazole, 2,6-dimethoxybenzothiazole, 5-hydroxy-6 Methylbenzothiazole, tetrahydrobenzothiazole, 4-phenylbenzothiazole), naphthothiazole ring (eg, naphtho [2,1-
d] thiazole, naphtho [1,2-d] thiazole, naphtho [2,3-d] thiazole, 5-methoxynaphtho [1,2-d] thiazole, 7-ethoxynaphtho [2,
1-d] thiazole, 8-methoxynaphtho [2,1-
d] thiazole, 5-methoxynaphtho [2,3-d] thiazole)},

Thiazoline ring (eg, thiazoline, 4-methylthiazoline, 4-nitrothiazoline), oxazole ring ｛oxazole ring (eg, oxazole, 4-methyloxazole, 4-nitrooxazole, 5-methyloxazole, 4-phenyloxazole) , 4,5-diphenyloxazole, 4-ethyloxazole), a benzoxazole ring (eg, benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole,
5-bromobenzoxazole, 5-fluorobenzoxazole, 5-phenylbenzoxazole, 5-methoxybenzoxazole, 5-nitrobenzoxazole, 5-trifluoromethylbenzoxazole,
-Hydroxybenzoxazole, 5-carboxybenzoxazole, 6-methylbenzoxazole, 6-
Chlorobenzoxazole, 6-nitrobenzoxazole, 6-methoxybenzoxazole, 6-hydroxybenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5-ethoxybenzoxazole), naphthoxazole ring (example) , Naphtho [2,1-d] oxazole, naphtho [1,2-d] oxazole, naphtho [2,3-d] oxazole, 5-nitronaphtho [2,1-d] oxazole},

Oxazoline ring (eg, 4,4-dimethyloxazoline), selenazole ring ｛selenazole ring (eg,
4-methyl selenazole, 4-nitro selenazole, 4
-Phenyl selenazole), benzo selenazole ring (eg, benzo selenazole, 5-chlorobenzo selenazole, 5-nitro benzo selenazole, 5-methoxy benzo selenazole, 5-hydroxy benzo selenazole, 6-nitro benzo selen Zole, 5-chloro-6-
Nitrobenzoselenazole, 5,6-dimethylbenzoselenazole), naphthoselenazole ring (eg, naphtho [2,1-d] selenazole, naphtho [1,2-d] selenazole)}, selenazoline ring (eg, selenazoline) ,
4-methylselenazoline), a tellurazole ring, a tellurazole ring (eg, tellurazole, 4-methyltellurazole,
4-phenyltellurazole), benzotellurazole ring (eg, benzotellurazole, 5-chlorobenzotellurazole, 5-methylbenzotellurazole, 5,6-dimethylbenzotellurazole, 6-methoxybenzotellurazole), naphtho Tellurazole ring (eg, naphtho [2,1-
d] tellurazole, naphtho [1,2-d] tellurazole,｝,

Terrazoline ring (eg, tellurazoline, 4-
Methyltellrazolin), 3,3-dialkylindolenine ring (eg, 3,3-dimethylindolenine, 3,3-diethylindolenine, 3,3-dimethyl-5-cyanoindolenine, 3,3-dimethyl- 6-nitroindolenine, 3,3-dimethyl-5-methoxyindolenine,
3,3,5-trimethylindolenine, 3,3-dimethyl-5-chloroindolenine),

Imidazole ring ｛imidazole ring (eg, 1
-Alkylimidazole, 1-alkyl-4-phenylimidazole, 1-arylimidazole), benzimidazole ring (eg, 1-alkylbenzimidazole,
1-alkyl-5-chlorobenzimidazole, 1-alkyl-5,6-dichlorobenzimidazole, 1-alkyl-5-methoxybenzimidazole, 1-alkyl-5-cyanobenzimidazole, 1-alkyl-5
-Trifluoromethylbenzimidazole, 1-alkyl-6-chloro-5-cyanobenzimidazole, 1-
Alkyl-6-chloro-5-trifluoromethylbenzimidazole, 1-allyl-5,6-dichlorobenzimidazole, 1-allyl-5-chlorobenzimidazole, 1-arylbenzimidazole 1-aryl-5
-Chlorobenzimidazole, 1-aryl-5,6-
Dichlorobenzimidazole, 1-aryl-5-methoxybenzimidazole, 1-aryl-5-cyanobenzimidazole), naphthobenzimidazole ring (eg, 1-alkylnaphtho [1,2-d] imidazole, 1-arylnaphtho [ 1,2-d] imidazole); the alkyl group shown in the above example of the imidazole ring is
With 1 to 8 carbon atoms, for example, methyl, ethyl,
Unsubstituted alkyl groups such as propyl, isopropyl, and butyl, or hydroxyalkyl groups (eg, 2-hydroxyethyl, 3-hydroxypropyl) are preferred, and methyl and ethyl groups are particularly preferred. The aryl group represents phenyl, a halogen atom (eg, chlorine atom) substituted phenyl, an alkyl (eg, methyl) substituted phenyl, an alkoxy (eg, methoxy) substituted phenyl.

A pyridine ring (eg, 2-pyridine, 4-pyridine, 5-methyl-2-pyridine, 3-methyl-4-pyridine), a quinoline ring (eg, a quinoline ring (eg, 2-quinoline, 3-methyl-2 -Quinoline, 5-ethyl-2-quinoline, 6-methyl-2-quinoline, 6-nitro-2-quinoline, 8-fluoro-2-quinoline, 6-methoxy-
2-quinoline, 6-hydroxy-2-quinoline, 8-chloro-2-quinoline, 4-quinoline, 6-ethoxy-4
-Quinoline, 6-nitro-4-quinoline, 8-chloro-
4-quinoline, 8-fluoro-4-quinoline, 8-methyl-4-quinoline, 8-methoxy-4-quinoline, 6-
Methyl-4-quinoline, 6-methoxy-4-quinoline,
6-chloro-4-quinoline), isoquinoline ring (eg, 6
-Nitro-1-isoquinoline, 3,4-dihydro-1-
Isoquinoline, 6-nitro-3-isoquinoline)}, imidazo [4,5-b] quinoxaline ring (eg, 1,3-diethylimidazo [4,5-b] quinoxaline, 6-chloro-1,3-diallylimidazo [4,5-b] quinoxaline), oxadiazole ring, thiadiazole ring, tetrazole ring and pyrimidine ring. Among these, the nitrogen-containing heterocycle is preferably a benzothiazole ring, a naphthothiazole ring, a benzoxazole ring or a naphthoxazole ring.

R ² and R ³ are each generally an alkyl group having 1 to 18 carbon atoms, and examples of the unsubstituted alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and the like. Hexyl, octyl, dodecyl and octadecyl groups can be mentioned. Examples of the substituent of the substituted alkyl group include a carboxy group, a sulfo group, a cyano group, a halogen atom (eg, a fluorine atom, a chlorine atom, and a bromine atom), a hydroxy group, an alkoxycarbonyl group having 8 or less carbon atoms (methoxycarbonyl group). , Ethoxycarbonyl, phenoxycarbonyl, benzyloxycarbonyl), an alkoxy group having 8 or less carbon atoms (eg, methoxy, ethoxy, benzyloxy, phenethyloxy), a monocyclic aryloxy group having 15 or less carbon atoms (eg, phenoxy , P-tolyloxy), an acyloxy group having 8 or less carbon atoms (eg, acetyloxy,
Propionyloxy), an acyl group having 8 or less carbon atoms (eg, acetyl, propionyl, benzoyl), a carbamoyl group (eg, carbamoyl, N, N-dimethylcarbamoyl, morpholinocarbonyl, piperidinocarbonyl), a sulfamoyl group (sulfamoyl, N, N-dimethylsulfamoyl, morpholinosulfonyl, piperidinosulfonyl), aryl groups having 15 or less carbon atoms (eg, phenyl, 4-chlorophenyl, 4-methylphenyl, α-naphthyl) and 18 or less carbon atoms (E.g., methylthio, ethylthio).

Of these, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms is preferable. Further, the unsubstituted alkyl group includes methyl, ethyl, propyl, isopropyl, butyl and isobutyl; Preferred are 2-methoxyethyl, 3-methoxypropyl and ethoxyethyl as groups; methylthioethyl and methylthiopropyl as alkylthio-substituted alkyl groups; and 2-acetoxyethyl and 3-acetoxypropyl as alkoxy-substituted alkyl groups.

Each of n and m is preferably 0.

(X) _p represents a cation or an anion required to neutralize the ionic charge of the dye molecule. When the dye molecule other than (X) _p is neutral, Since p is not necessary, p becomes p is generally 1 or 1 /
2. Typical cations are ammonium ions,
It is an alkali metal ion. On the other hand, the anion may be an inorganic anion or an organic anion, for example,
Halogen anion (fluorine ion, chloride ion, bromine ion, iodine ion), substituted arylsulfonate ion (p-toluenesulfonate ion, p-chlorobenzenesulfonate ion), aryldisulfonate ion (eg, 1,3- Benzenesulfonic acid ion, 1,5-naphthalenedisulfonic acid ion, 2,6-naphthalenedisulfonic acid ion), alkyl sulfate ion (eg, methyl sulfate ion), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate Acid ion, picrate ion, acetate ion, trifluoromethanesulfonic acid ion, hexafluorophosphate ion, hexafluoroantimonate ion, tungstophosphate ion and bis (benzene-1,2-dithiolite) nickelate (II) ion Can be mentioned.

The cyanine dye represented by the general formula (I) is represented by the following general formula (II):

[0044]

Embedded image [However, R ¹ , R ² and R ³ have the same meanings as in the above general formula (I), and W ¹ and W ² represent —S— and —O
- or represents a -Se-, Z ³ and Z ⁴ are each a hydrogen atom, a chlorine atom, a methyl group, represents a benzene ring or a naphthalene ring optionally substituted with methoxy or propoxy group, these substituents X ₁ may represent a charge-neutralizing counter ion, and a cyanine dye represented by the formula:

Next, specific examples of the cyanine-based dye represented by formula (I) of the present invention will be described. Of course, the scope of the present invention is not limited only to these.

[0046]

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The compound represented by the general formula (I) of the present invention (that is, a methine chain having a 6-membered ring formed by a trimethylene bridging group at positions 2 and 4 and an alkyl or aryl group at the position 2) Compound with a structure substituted by only one)
Are already described as sensitizing dyes in U.S. Pat. No. 2,481,022. The compounds of the present invention described in the examples of the above-mentioned US patents can be synthesized according to the description. Compounds of the present invention not specifically described in the above-mentioned U.S. patents can also be easily synthesized based on the examples and examples of the above-mentioned U.S. patents.

Further, British Patent Nos.
Nos. 5784, 595785, 604217, U.S. Pat. Nos. 2,481,022 and 2,756,227, Sensitization Science and Photochemical (p. 39, 1987), Journal of Imaging Science (Journal of Imaging S)
cience, 32, 81, 1988), or FM Hamer, Heterocylclic Compounds-Cyanine dyes.
and related compounds-)], John Wiley & Sons, Inc.-New York, London, 1964;
(DMSturmer), Heterocyclic Compounds-Special Topics in Heterocyclic Chemistry-
opics in heterocyclic chemistry-) ", Chapter 8, Chapter 4
, Pages 482-515, John Wiley & Sons, Inc.-New York, London, 1977, and the like.

Next, the synthesis method will be described with reference to synthesis examples of the compound represented by the general formula (I) of the present invention. Synthesis Example 1 (Synthesis of Dye 25) 6.0 g of the following compound (T-1) and the following compound (M-
1) 2.0 g of the mixture was stirred for 10 hours while heating to 180 ° C. After cooling, the reaction solution was purified by silica gel chromatography (eluent: dichloromethylene / methanol) to obtain a paratoluenesulfonic acid compound (S-
1) was obtained. (S-1) 1.6 g of methanol in 50 ml
And a solution of 1.5 g of sodium iodide in 30 ml of methanol was added at room temperature with stirring.
The precipitated crystals were separated by filtration, washed with 20 ml of methanol, and dried to obtain 1.4 g of the desired dye. Yield: 22% λ _max : 649.9 nm (methanol) ε: 1.74 × 10 ⁵ Melting point: 186 ° C

[0050]

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Synthesis Example 2 (Synthesis of Dye 26) 3.0 g of the following compound (T-1) and the following compound (M-
2) 0.8 g of the mixture was stirred for 1 hour while heating to 140 ° C. After cooling the reaction solution, 10 ml of acetonitrile and 1.0 ml of triethylamine were added, and the mixture was heated under reflux for 1 hour. After cooling the reaction solution, 50 ml of a solution of 2.0 g of sodium iodide dissolved in methanol was added, and the precipitated crystals were separated by filtration. The obtained crude crystals were dissolved in a dichloromethane / methanol mixed solution, and the solvent was distilled off under reduced pressure to recrystallize, thereby obtaining 1.70 g of a desired dye. Yield: 53% λ _max : 645.5 nm (methanol) ε: 1.83 × 10 ⁵ Melting point: 242 ° C.

[0052]

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In the present invention, the above-mentioned general formula (I) of the present invention
May be used alone or in combination of two or more. Further, any dye conventionally known as a recording material for an information recording medium may be used in combination. For example, other than the dyes used in the present invention, cyanine dyes, phthalocyanine dyes, pyrylium / thiopyrylium dyes, azulenium dyes, squarylium dyes, metal complex salt dyes such as Ni and Cr, naphthoquinone / anthraquinone dyes And indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium / diimmonium dyes, and nitroso compounds.

Further, in order to improve the light fastness, various dyes known as a so-called singlet oxygen quencher, for example, a compound represented by the following general formula (III) or (IV) may be used in combination.

[0055]

Embedded image (However, [Cat] ⁺ represents a nonmetallic cation such as tetraalkylammonium, M represents a transition metal atom such as Ni, and A and A ′ are an optionally substituted benzene ring, 2-thioxo-1 Represents a group of atoms for completing a 5- or 6-membered aromatic or heterocyclic ring such as a 1,3-dithiol ring)

[0056]

Embedded image [Wherein R represents an alkyl group which may have a substituent, and Y represents the same anion as that represented by X in the general formula (I)]. The above general formula (III) or (IV) Specific examples of the quencher represented by
(Mitsui Toatsu Fine Co., Ltd.) and IRG-023 (Nippon Kayaku Co., Ltd.).

The recording layer is formed by dissolving the above dye, and if desired, the above quencher and the following binder in a solvent to prepare a coating solution, and then applying this coating solution to the substrate surface to form a coating film. After forming, it can be carried out by drying. In the present invention, a cation of the dye,
A conjugate with the anion of the quencher can also be used. The quencher is generally used at 0.
It is used in an amount of from 05 to 12 mol, preferably from 0.1 to 1.2 mol.
The quencher is preferably contained in the dye thin film recording layer, but may be contained in a layer different from the recording layer.

The recording layer is formed by dissolving the dye (optionally adding the quencher and the binder) in an organic solvent to prepare a coating solution, and then coating the coating solution on the substrate surface. It can be performed by drying after forming the film. As the solvent for the dye coating solution preparation,
Ester such as ethyl acetate, butyl acetate, cellosolve acetate, ketone such as methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, dichloromethane,
Halogenated hydrocarbons such as 1,2-dichloroethane and chloroform; ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol and n-butanol; amides such as dimethylformamide; ,
3. Fluorinated solvents such as tetrafluoropropanol.

When the dye recording layer of the present invention is provided, it is preferable to use a fluorinated solvent as an organic solvent to be added to the coating solution, thereby promoting the association formation of the dye monomer and efficiently and easily. A dye recording layer having an absorption maximum at a wavelength (preferably, at least 70 nm longer than the absorption maximum wavelength of an ethanol solution of the dye) can be formed.

Examples of the fluorinated solvent (fluorine-containing compound) used in the present invention include fluorinated alcohols, fluorinated ketones, fluorinated esters, fluorinated carboxylic acids, fluorinated amides, fluorinated benzenes, fluorinated alkanes and the like. Fluorinated ethers can be mentioned. The fluorine-based solvent (fluorine-containing compound) is disclosed in
No. 3-159090 (U.S. Pat. No. 4,832,992)
No.).

As the fluorinated alcohol, for example, a compound represented by the general formula (V): A-CH ₂ OH (V) (where A is F (C _n F _2n ) or H (C _n F _2n ), and n is 1 Which is an integer of from 1 to 6), and A may be linear or branched. Specific examples thereof include the following compounds.

H-CF ₂ -CF ₂ -CH ₂ OH, H-CF ₂ -CF ₂ -CF ₂ -CF ₂ -CH
_{2 OH, CF 3 -CH 2 OH} , F-CF 2 -CF 2 -CH 2 OH, F-CF 2 -CF 2 -CF
₂ -CF ₂ -CH ₂ OH, the concentration of the dye in the coating solution is based on the total weight of the coating solution.
0.1-20% by weight is preferred, and particularly preferred is 1-5
% By weight.

Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added to the coating solution according to the purpose.

When a binder is used, the binder may be
For example, gelatin, nitrocellulose, cellulose derivatives such as cellulose acetate, dextran, rosin, natural organic high molecular substances such as rubber; and hydrocarbon resins such as polyethylene, polypropylene, polystyrene and polyisobutylene, polyvinyl chloride, polyvinylidene chloride, Vinyl resins such as polyvinyl chloride / polyvinyl acetate copolymers,
Synthetic organic polymers such as acrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl alcohol, chlorinated polyolefins, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol and formaldehyde resins Substances can be mentioned.

Examples of the coating 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. 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 to 9%.
9% (weight ratio), preferably 1.0 to 95%
% (Weight ratio).

In the recording layer or in a layer adjacent thereto,
In order to prevent the deterioration of the dye, an antioxidant or an anti-fading agent may be present. The recording layer may be a single layer or a multilayer, but the layer thickness is generally in the range of 0.01 μm to 2 μm,
Preferably it is in the range of 0.02 to 0.8 μm. The recording layer may be provided not only on one side of the substrate but also on both sides.

When the dye recording layer of the present invention is provided, the formation of dye association is promoted by using a fluorine-based solvent as the organic solvent as described above to efficiently and easily form a long wavelength (preferably an ethanol solution of the dye). 70 nm from the absorption maximum wavelength indicated by
It is preferable to form a dye recording layer having an absorption maximum at a longer wavelength (above long wavelength) because light absorption becomes large in the oscillation wavelength region of a laser used during recording or reproduction.

As a method for forming a dye recording layer so as to have an absorption maximum at a longer absorption maximum wavelength, for example, after preparing a coating solution containing the above dye and a fluorine-based solvent, the coating solution is formed on a substrate. This is performed by applying and drying a coating solution. That is, it is extremely effective to apply a dye coating solution containing a fluorine-based solvent (and appropriately containing another organic solvent and a binder) to form a dye recording layer comprising an association of the dye monomer. It means there is. Since such an association state of the dye is presumed to be easily formed near a critical point at which the dye can be dissolved,
Although a coating solution containing no fluorine-based solvent may be formed in some cases, the use of a fluorine-based solvent has the advantage that the preparation of the coating solution is extremely easy and the associated state is easily formed. In addition, the method of applying the dye after stretching the substrate in a certain direction or rubbing the surface, forming a layer on the substrate by vapor deposition of silver halide or the like before applying the dye, A method of promoting the alignment of the dye, a method of increasing the concentration of the coating solution to associate the dye monomer in the coating solution, a method of adding a salt or a resin to the coating solution, or a method of forming a dye layer and then mechanically applying the dye layer. For example, a method of applying a thermal or thermal stimulus to change the dye monomer into an associated state can be used.

Further, in the information recording medium of the present invention, a reflective layer may be provided on the above-mentioned recording layer for the purpose of improving the C / N and the reflectivity 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,
Ni, 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 10 to 300 nm.

Further, a recording layer and the like are physically placed on the reflective layer.
Protective layer is provided for the purpose of protecting chemically and chemically
Good. This protective layer is not provided with the recording layer of the substrate
It may be provided on the side for the purpose of enhancing scratch resistance and moisture resistance.
No. Examples of the material used for the protective layer include SiO, S
iO_Two , MgF_Two , SnO _Two , Si_Three N_Four Inorganic substances such as
Quality: Thermoplastic resin, thermosetting resin, UV curable resin, etc.
Organic substances can be mentioned. The protective layer
The film obtained by the extrusion of the plastic is passed through the adhesive layer.
On the recording layer (or silver halide layer or reflective layer) and / or
Or by laminating on a substrate
Can be. Or vacuum deposition, sputtering, coating, etc.
May be provided by the above method. Also, thermoplastic resin,
In the case of thermosetting resins, dissolve them in a suitable solvent.
After preparing the coating solution, apply the coating solution and dry it.
Can also be formed. UV curable tree
In the case of fat, dissolve as it is or in a suitable solvent
After preparing the coating liquid, apply this coating liquid and irradiate it with UV light.
Can also be formed by curing
You. In these coating solutions, antistatic agent, antioxidant
Various additives such as UV absorbers and UV absorbers
Is also good. The thickness of the protective layer is generally 0.1 to 100 μm.
In range.

In the present invention, the information recording medium may be a single plate having the above-described structure, or two substrates having the above-described structure may be faced so that the recording layer is on the inside, and an adhesive or the like may be used. By using the bonding method, a bonding type recording medium can 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.

A method for recording and reproducing information using the information recording medium is performed, for example, as follows. First, 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, recording light such as a semiconductor laser beam is irradiated from the substrate side. By irradiating this light, the information is changed by changing the associated state of the recording layer made of the dye which is in the associated state when the laser power is low (usually, the laser irradiation makes the associated state more dense and changes to a state closer to a crystal). Is recorded. When the laser power is large, information is recorded by forming a concave portion (pit) in a recording layer made of a dye in an associated state. However, when a reflective layer or a protective layer is formed on the recording layer, it is difficult to form a concave portion. Generally, a semiconductor laser beam having an oscillation wavelength in the range of 750 nm to 850 nm is used as the recording light. Reproduction of information can be performed by irradiating a laser beam having the same oscillation wavelength as above from the substrate side while rotating the information recording medium at the same constant linear speed as above, and detecting the reflected light. .

[0073]

EXAMPLES Examples of the present invention will be described below. However, these examples do not limit the present invention.

Example 1 Cyanine dye (the above dye 2
5) 2.3 g of 2,2,3,3-tetrafluoro-1-
1. Dissolve in propanol (structural formula: HCF ₂ CF ₂ CH ₂ OH)
A dye coating solution having a concentration of 3% by weight was prepared. 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 depth: 80 n
m) On top of this, the coating solution was spin-coated at 180 rpm.
After coating at 0 rpm, the coating was dried for 100 seconds to form a recording layer having a layer thickness of 130 nm. Thus, an information recording medium including the substrate and the recording layer was manufactured. Similarly, a total of 100 information recording media were prepared.

Example 2 An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 26. Similarly, a total of 100 information recording media were prepared.

Example 3 An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 27. Similarly, a total of 100 information recording media were prepared.

Example 4 An information recording medium was manufactured in the same manner as in Example 1, except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 28. Similarly, a total of 100 information recording media were prepared.

Example 5 An information recording medium was manufactured in the same manner as in Example 1, except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 29. Similarly, a total of 100 information recording media were prepared.

Example 6 An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 33. Similarly, a total of 100 information recording media were prepared.

Example 7 An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared by changing the cyanine dye (the dye 25) to the dye 34. Similarly, a total of 100 information recording media were prepared.

[Comparative Example 1] In Example 1, a cyanine-based dye (the aforementioned dye 25) was replaced with a dye A having the following structural formula.
An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared in place of the above. Dye A:

[0082]

Embedded image Similarly, a total of 100 information recording media were prepared.

[Comparative Example 2] In Example 1, a cyanine-based dye (the aforementioned dye 25) was replaced with a dye B having the following structural formula.
An information recording medium was manufactured in the same manner as in Example 1 except that a dye coating solution was prepared in place of the above. Dye B:

[0084]

Embedded image Similarly, a total of 100 information recording media were prepared.

The information recording medium thus obtained was evaluated as follows. [Evaluation of Information Recording Medium] 1) Reflectivity Using a spectrophotometer (manufactured by Hitachi, Ltd.), 100 pieces of information recording media obtained in each example were irradiated with light having a wavelength of 780 nm from the substrate side. And the reflectance was measured. The average is shown.

2) Standard Deviation The reflectance was measured for the 100 information recording media obtained in each example as described above, and the standard deviation was obtained.

3) C / N The 100 information recording media obtained above were subjected to a wavelength of 780
1.3m constant linear velocity using semiconductor laser light
/ S at a recording power of 7.0 mW and a modulation frequency of 196 k
Hz (duty 45%) signal was recorded. Then, the recorded signal is reproduced with a reproduction power of 0.5 mW,
The C / N at the time of reproduction is measured using a spectrum analyzer (TR41).
35: manufactured by Advantest Corporation). The average is shown.

Table 1 shows the measurement results.

[0089]

TABLE 1 TABLE 1 ──────────────────────────── dye reflectance standard deviation C / N No. (%) ( dB) ──────────────────────────── Example 1 25 52 0.41 49 Example 2 26 55 0.53 48 Example 3 27 54 0.46 50 Example 4 28 53 0.51 49 Example 5 29 52 0.63 49 Example 6 33 52 0.56 48 Example 7 34 51 0.74 48} {Comparative Example 1 A 51 6.28 32 Comparative Example 2 B 27 3.13 48} ───────────────

[0090]

According to the present invention, the recording layer of the information recording medium comprises a cyanine dye having five methine chains and two or four methine chains.
A 6-membered ring formed by a trimethylene bridging group at the 1-position, and the 2-position of the 6-membered ring is substituted by an alkyl group or an aryl group to form a cyanine dye represented by the above general formula (I). . By using the cyanine dye, the obtained information recording medium has a high reflectance and a high level of recording / reproducing characteristics, and such a product can be manufactured stably (at a high yield). This is because, since only one of the 2-positions of the 6-membered ring is substituted, the dye is asymmetric at the center of the molecule, so that when the dye layer is formed, the dye is easily aggregated and the aggregation state is stable. It is assumed that a high reflectance can be obtained stably. Thus, the information recording medium of the present invention
Since it has a high reflectivity, it can be read with low power during reproduction, so that it can be easily applied to various drives, and has the advantage that the read durability is also improved. Further, excellent recording and reproducing characteristics are easily obtained.
In other words, an optical disc having excellent characteristics can be stably manufactured at a high yield, so that it can be said that the information recording medium is excellent in productivity.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-146966 (JP, A) JP-A-3-274183 (JP, A) JP-A-3-207693 (JP, A) 502120 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/26 G11B 7/24 516 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. An information recording medium provided with a recording layer made of a dye on which information can be written by a laser beam on a substrate, wherein the recording layer has the following general formula (I): Wherein R ¹ represents an alkyl group, an aryl group or a heterocyclic group; Q ¹ and Q ² represent a methylene group;
L ¹ , L ² , L ³ , L ⁴ and L ⁵ represent a methine group, n represents 0 or 1, m represents 0 or 1, and Z ¹ represents N ⁺ = (L ² − L ³⁾ _n = represents an atomic group necessary for forming a nitrogen-containing heterocyclic 5- or 6-membered with C, Z ²
Represents an atomic group necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring together with C = (L ⁴ -L ⁵ ) _m = N, and R ² and R ³
Represents an alkyl group, X represents a counter ion for neutralizing a charge, and p represents a positive number (however, 0 when there is no charge to neutralize in the molecule). An information recording medium comprising a cyanine dye represented by the formula: