JP2001063211A - Optical information recording medium containing bispyridinium compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording method of high reflectance, high sensitivity and high modulation factor. SOLUTION: In an information recording medium with a recording layer whereon information can be recorded by emitting laser beams of 550 nm or less wavelength on a base, the recording layer is an information recording medium containing a bispyridinium compound represented by a formula. In the formula, R1 and R2 represent independently substituents, R3 and R4 represent respectively alkyl, alkenyl, alkynyl, aralkyl, aryl or heterocyclic group, and R1 can be connected with R2, R1 can be connected with R3, R2 can be connected with R4, or R3 can be connected with R4 respectively to form rings, and (r) and (s) represent respectively 0-4 integers, and in the case (r) and (s) represent 2 or more, R1 and R2 forming a plurality can be same or different. -Xp- represents anions, (p) represents an integer of 1 or more, and (q) represents a number required for balancing the electric charge.

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 on which information can be written by using a laser beam having a high energy density, and more particularly to a compound which can be advantageously used for producing an information recording medium.

[0002]

2. Description of the Related Art An information recording medium (optical disk) on which information can be recorded only once by a laser beam has been known. The information recording medium is a write-once CD (a so-called CD-
R), a smaller amount of CD compared to the conventional CD production
Is affordable and can be quickly provided, and the demand for personal computers has been increasing with the recent spread of personal computers. A typical structure of a CD-R type information recording medium is one in which a recording layer made of an organic dye, a reflective layer made of a metal such as gold, and a protective layer made of a resin are further laminated in this order on a transparent disk-shaped substrate. It is. Recording of information on the optical disk is performed using laser light in the near infrared region (normally 780 nm).
This is performed by irradiating a laser beam having a nearby wavelength) to locally generate and deform the recording layer. On the other hand, reading (reproducing) information is usually performed by irradiating a laser beam having the same wavelength as the recording laser beam to reflect a portion where the recording layer is heated and deformed (recorded portion) and a portion where the recording layer is not deformed (unrecorded portion). It does this by detecting differences in rates.

In recent years, an information recording medium having a higher recording density has been demanded. To increase the recording density, it is effective to reduce the diameter of the laser beam to be irradiated, and it is theoretically known that laser light having a shorter wavelength can be reduced to a smaller diameter, which is advantageous for increasing the density. Have been. Therefore, the development of an optical disc for recording and reproducing using a laser beam having a wavelength shorter than 780 nm, which has been conventionally used, has been advanced.

On the other hand, Japanese Patent Application Laid-Open No. 63-209959 discloses a CD-R type information recording medium in which a recording layer comprising an oxonol dye is provided on a substrate. It is described that by using this dye compound, stable recording / reproducing characteristics can be maintained for a long period of time. The publication describes an oxonol dye compound in which ammonium is introduced in the form of a salt in the molecule.

[0005]

As a result of various studies, the present inventors have found that if a bispyridinium compound is used as the compound for the recording layer, the bis-pyridinium compound is used for the CD-R.
Laser light having a wavelength much shorter than 0 nm (for example, wavelength 5
It has been found that a recording pit can be formed without any problem even by a laser beam having a wavelength of 50 nm or less, and a sufficient reflectance can be obtained practically. Accordingly, a main object of the present invention is to provide an information recording medium capable of suitably recording and reproducing information by irradiating a laser beam having a wavelength of 550 nm or less, and an information recording method using the information recording medium. It is to provide.

[0006]

According to the present invention, by using the bispyridinium compound represented by the general formula (I-1) for the recording layer, excellent recording / reproducing characteristics with respect to laser light having a wavelength of 550 nm or less are obtained. Has been found. The problem has been solved by the following (1) to (3). (1) In an information recording medium in which a recording layer capable of recording information by irradiating a laser beam having a wavelength of 550 nm or less on a substrate is provided, the recording layer is represented by the following general formula (I-1). An information recording medium comprising a bispyridinium compound represented by the formula:

[0007]

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[Wherein R ₁ and R ₂ each independently represent a substituent, and R ₃ and R ₄ each independently represent an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group or a heterocyclic ring. R ₁ and R ₂ , R ₁ and R ₃ , R ₂ and R _4, or R ₃ and R ₄ may be connected to each other to form a ring, and r and s each independently represent 0 to And when r and s are 2 or more, a plurality of R ₁ and R ₂ may be the same or different from each other.
^Xp- represents an anion, p represents an integer of 1 or more, and q represents a number necessary for balancing electric charges. (2) The information recording medium according to (1), wherein a reflective layer is provided on the recording layer. (3) The information recording medium according to (1) or (2), wherein the wavelength of the laser light is 390 to 450 nm.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The information recording medium of the present invention is characterized in that the recording layer contains a bispyridinium compound represented by the following general formula (I-1).

[0010]

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The bispyridinium compound according to the present invention comprises
It is composed of a bispyridinium component having a cationic property (hereinafter simply referred to as a cation part) and a component having an anionic property (hereinafter simply referred to as an anion part). First, the cation portion will be described in detail.

In the formula, R ₁ and R ₂ each independently represent a substituent, and R ₃ and R ₄ each independently represent an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group or a heterocyclic group. R ₁ and R ₂ , R ₁ and R ₃ , R ₂ and R ₄ or R ₃ and R ₄ may be mutually connected to form a ring, and r and s each independently represent 0 to 4 Represents the integer of
When r and s are 2 or more, a plurality of R ₁ and R ₂
May be the same or different from each other.

The alkyl group represented by R ₃ and R ₄ is preferably a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. is there. These may be linear, branched, or cyclic. Examples of these include methyl, ethyl, n-propyl, isopropyl, n
-Butyl, isobutyl, t-butyl, n-hexyl, neopentyl, cyclohexyl, adamantyl, cyclopropyl and the like.

Examples of the substituent of the alkyl group include the following. A substituted or unsubstituted alkenyl group having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms) (eg vinyl); 2 to 18 carbon atoms (preferably 2 carbon atoms)
To 8) substituted or unsubstituted alkynyl groups (eg, ethynyl); substituted or unsubstituted aryl groups having 6 to 10 carbon atoms (eg, phenyl, naphthyl); halogen atoms (eg,
F, Cl, Br and the like); a substituted or unsubstituted alkoxy group having 1 to 18 carbon atoms (preferably 1 to 8 carbon atoms) (eg,
Methoxy, ethoxy); a substituted or unsubstituted aryloxy group having 6 to 10 carbon atoms (eg, phenoxy, p-methoxyphenoxy); substituted or unsubstituted having 1 to 18 carbon atoms (preferably 1 to 8 carbon atoms). Alkylthio group (eg,
Methylthio, ethylthio); a substituted or unsubstituted arylthio group having 6 to 10 carbon atoms (eg, phenylthio);
A substituted or unsubstituted acyl group having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms) (eg, acetyl, propionyl);

C1-18 (preferably C1-18)
8) a substituted or unsubstituted alkylsulfonyl group or arylsulfonyl group (eg, methanesulfonyl, p-
A substituted or unsubstituted acyloxy group having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms) (eg, acetoxy, propionyloxy);
18 (preferably 2 to 8 carbon atoms) substituted or unsubstituted alkoxycarbonyl group (eg, methoxycarbonyl,
Ethoxycarbonyl); a substituted or unsubstituted aryloxycarbonyl group having 7 to 11 carbon atoms (eg, naphthoxycarbonyl); an unsubstituted amino group, or 1 to 1 carbon atom
18 (preferably 1 to 8 carbon atoms) substituted amino group (eg,
Methylamino, dimethylamino, diethylamino, anilino, methoxyphenylamino, chlorophenylamino, pyridylamino, methoxycarbonylamino, n-
Butoxycarbonylamino, phenoxycarbonylamino, methylcarbamoylamino, ethylthiocarbamoylamino, phenylcarbamoylamino, acetylamino, ethylcarbonylamino, ethylthiocarbamoylamino, cyclohexylcarbonylamino, benzoylamino, chloroacetylamino, methylsulfonylamino);

C1 to C18 (preferably C1 to C18)
8) substituted or unsubstituted carbamoyl group (eg, unsubstituted carbamoyl, methylcarbamoyl, ethylcarbamoyl, n-butylcarbamoyl, t-butylcarbamoyl, dimethylcarbamoyl, morpholinocarbamoyl, pyrrolidinocarbamoyl); unsubstituted sulfamoyl group Or 1 to 18 carbon atoms (preferably 1 to 18 carbon atoms)
8) a substituted sulfamoyl group (eg, methylsulfamoyl, phenylsulfamoyl); a cyano group; a nitro group;
Carboxy group; hydroxyl group; heterocyclic group (eg, oxazole ring, benzoxazole ring, thiazole ring, benzothiazole ring, imidazole ring, benzimidazole ring, indolenine ring, pyridine ring, pyrimidine ring, piperidine ring, pyrrolidine ring, morpholine ring , Sulfolane ring, furan ring, thiophene ring, pyrazole ring, pyrrole ring, chroman ring, coumarin ring).

The alkenyl group represented by R ₃ and R ₄ is preferably a substituted or unsubstituted alkenyl group having 2 to 18 carbon atoms, more preferably a substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms. Yes, for example, vinyl,
Allyl, 1-propenyl, 1,3-butadienyl and the like can be mentioned. As the substituent for the alkenyl group, those mentioned above as the substituent for the alkyl group are preferable.

The alkynyl group represented by R ₃ and R ₄ is preferably a substituted or unsubstituted alkynyl group having 2 to 18 carbon atoms, more preferably a substituted or unsubstituted alkynyl group having 2 to 8 carbon atoms. Yes, for example, ethynyl, 2-propynyl and the like. As the substituent for the alkynyl group, those described above as the substituent for the alkyl group are preferable.

The aralkyl group represented by R ₃ and R ₄ is preferably a substituted or unsubstituted aralkyl group having 7 to 18 carbon atoms, such as benzyl and methylbenzyl. Examples of the substituent of the aralkyl group include those described above as the substituent of the alkyl group.

The aryl group represented by R ₃ and R ₄ is preferably a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, such as phenyl and naphthyl. As the substituent of the aryl group, those described above as the substituent of the alkyl group are preferable. In addition to these, an alkyl group (eg, methyl, ethyl, etc.) is also preferable.

The heterocyclic group represented by R ₃ and R ₄ is
It is a 5- or 6-membered saturated or unsaturated heterocyclic ring composed of a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and examples thereof include an oxazole ring, a benzoxazole ring, a thiazole ring, and a benzothiazole. Ring, imidazole ring, benzimidazole ring, indolenine ring,
Examples include a pyridine ring, a pyrimidine ring, a piperidine ring, a pyrrolidine ring, a morpholine ring, a sulfolane ring, a furan ring, a thiophene ring, a pyrazole ring, a pyrrole ring, a chroman ring, and a coumarin ring. The heterocyclic group may be substituted, and in this case, the substituent is preferably those exemplified as the substituent for the alkyl group.

The substituents represented by R ₁ and R ₂ have the same meanings as those described above for the alkyl group. In addition to these, alkyl groups (eg, methyl, ethyl, etc.)
Can also be mentioned. In the present invention, R ₁ and R
_The substituent represented by ₂ is preferably a hydrogen atom or an alkyl group. Particularly preferred is a hydrogen atom.

In formula (I-1), the cation moiety is particularly preferably represented by the following formula (I-2) or (I-3).

[0024]

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Where R_FiveAnd R₆Are respectively described above
R₁And R_TwoHas the same meaning as the substituent represented by
The preferred ranges are the same for each. R₇Passing
And R ₈Is the above-mentioned R_ThreeAnd R_FourThe position represented by
Synonymous with a substitution group, and for each, its preferred
Are the same. r and s are each independently 0 to 4
Represents an integer, and when r and s are 2 or more,
R_FiveAnd R₆Are different from each other even if they are the same
Is also good.

[0026]

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In the formula, R ₉ and R ₁₀ have the same meanings as the substituents represented by R ₁ and R ₂ described above, respectively, and the preferred ranges thereof are also the same. It is also preferred that R ₉ and R ₁₀ are connected to each other to form a carbocyclic or heterocyclic ring, and it is particularly preferable that R ₉ and R ₁₀ be a condensed aromatic ring with a pyridine ring to which R ₉ and R ₁₀ are respectively bonded. . r and s each independently represent an integer of 0 to 4,
When r and s are 2 or more, a plurality of R ₉ and R ₁₀
May be the same or different from each other.

Next, the anion portion will be described in detail. X ^p-
May be either an inorganic anion or an organic anion, for example, a halogen anion (for example, a fluorine ion, a chloride ion, a bromine, an iodine ion), a sulfonate ion (for example, methane sulfone) Acid ion, trifluoromethanesulfonic acid ion, methyl sulfate ion, p-toluenesulfonic acid ion, p-
Chlorobenzenesulfonic acid ion, 1,3-benzenedisulfonic acid ion, 1,5-naphthalenedisulfonic acid ion, 2,6-naphthalenedisulfonic acid ion, etc.),
Examples thereof include sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, picrate ion, acetate ion, phosphate ion (for example, hexafluorophosphate ion), and oxanol dye. .

P represents an integer of 1 or more (preferably 1 to 4), q represents a number (0 or more, preferably 0 to 4) necessary for balancing electric charge, and forms a salt in the molecule. In this case, it is 0. The bispyridinium compound represented by the general formula (I-1) may form a bis-type structure by linking two kinds on any carbon atom.

The bispyridinium compound represented by the general formula according to the present invention (I-1) is 2,2'-bipyridyl or 4,4 ^'- Menschutkin reaction of a halogen compound having the desired substituent bipyridyl ( For example, JP-A-61
-148162) or JP-A-51-1
It can be easily obtained by an arylation reaction according to the method described in JP-A-6675 / 1994 and JP-A-1-96171.

The bispyridinium compound represented by the general formula (I-1) according to the present invention may be used alone,
Alternatively, two or more kinds may be used in combination. Alternatively, the bispyridinium compound according to the present invention may be used in combination with a dye compound conventionally known as a dye compound for an information recording medium. Examples of these include oxono-
Dyes, cyanine dyes, azo metal complexes, phthalocyanine dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, squarylium dyes, naphthoquinone dyes, triphenylmethane dyes, triallylmethane dyes, etc. Can be mentioned.

Specific examples of the bispyridinium compound represented by formula (I-1) used in the present invention are described below.

[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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The recording layer preferably contains various anti-fading agents in order to improve the light resistance of the recording layer. Generally, a singlet oxygen quencher is used as an anti-fading agent. As the singlet oxygen quencher, those described in publications such as publicly known patent specifications can be used. A specific example thereof is disclosed in Japanese Patent Laid-Open No. 58-1756.
No. 93, No. 59-81194, No. 60-18387
Nos. 60-19586, 60-19587, 60-35054, 60-36190, 60-
No. 36191, No. 60-44554, No. 60-445
No. 55, No. 60-44389, No. 60-44390
JP-A-60-54892, JP-A-60-47069, JP-A-63-209995, JP-A-4-25492, JP-B-1-38680, and JP-A-6-26028, and German Patent 350399. And pages 1141 of the Journal of the Chemical Society of Japan, October 1992, and the like. Preferred examples of the singlet oxygen quencher include a compound represented by the following general formula (II). General formula (II)

[0046]

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(However, R ²¹ represents an alkyl group which may have a substituent, and Q ⁻ represents an anion.)

In the general formula (II), R ²¹ is generally an optionally substituted alkyl group having 1 to 8 carbon atoms, preferably an unsubstituted alkyl group having 1 to 6 carbon atoms. Examples of the substituent of the alkyl group include a halogen atom (eg, F, Cl),
Alkoxy group (eg, methoxy, ethoxy), alkylthio group (eg, methylthio, ethylthio), acyl group (eg,
Acetyl, propionyl), acyloxy group (eg, acetoxy, propionyloxy), hydroxy group, alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl), alkenyl group (eg, vinyl), aryl group (eg, phenyl, naphthyl) Can be mentioned.
Among these, a halogen atom, an alkoxy group, an alkylthio group and an alkoxycarbonyl group are preferred. Preferred examples of the anion of Q ⁻ include ClO ⁴⁻ , AsF ⁶⁻ , BF ⁴⁻ , and SbF ⁶⁻ . Table 1 shows examples of the compound represented by the general formula (II).

[0049]

[Table 1]

The optical information recording medium of the present invention has a structure in which a recording layer, a light reflecting layer and a protective layer are provided in this order on a disk-shaped substrate on which pregrooves having a fixed track pitch are formed, or a light reflecting layer is formed on the substrate. It is preferable that the structure has a layer, a recording layer, and a protective layer in this order. In addition, two laminates in which a recording layer and a light reflection layer are provided on a transparent disc-shaped substrate on which a pre-groove having a constant track pitch is formed are joined so that each recording layer is on the inside. The above configuration is also preferable.

The optical information recording medium of the present invention has a higher recording density than a CD-R or DVD-R in order to achieve a higher recording density.
It is possible to use a substrate on which pre-groups with a smaller track pitch are formed. In the case of the optical information recording medium of the present invention, the track pitch is preferably 0.3 to 0.8 μm, more preferably 0.4 to 0.6 μm.

The optical information recording medium of the present invention can be manufactured, for example, by the following method. The substrate of the optical information recording medium can be arbitrarily selected from various materials used as the substrate of the conventional optical information recording medium. As the substrate material, for example, glass, polycarbonate, acrylic resin such as polymethyl methacrylate,
Examples thereof include polyvinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymer, epoxy resins, amorphous polyolefins and polyesters, and these may be used in combination if desired. 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 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-methylol acrylamide, styrene / vinyl toluene copolymer, and chlorosulfonation. 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 the like. 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.

The recording layer is formed by dissolving the bispyridinium compound and, if desired, a dye, a quencher, a binder and the like in a solvent to prepare a coating solution, and then applying the coating solution to the substrate surface to form a coating film. After forming, it can be carried out by drying. Solvents for the coating solution of the bispyridinium compound-containing layer include esters such as 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 and n-butanol diacetone alcohol;
Fluorinated solvents such as 2,3,3-tetrafluoropropanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether; The above solvents can be used alone or in combination of two or more in consideration of the solubility of the bispyridinium compound 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 amount of the binder used is generally in the range of 0.01 times to 50 times (by weight) the bispyridinium compound, and preferably 0.1 times. It is in the range of twice to five times (weight ratio). The concentration of the coating solution thus prepared is generally in the range of 0.01 to 10% by weight, preferably in the range of 0.1 to 5% by weight.

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. The recording layer may be a single layer or a multilayer. The thickness of the recording layer is generally in the range from 20 to 500 nm, preferably in the range from 50 to 300 nm.

It is preferable to provide a light reflection layer on the recording layer for the purpose of improving the reflectance at the time of reproducing information.
The light-reflective substance, which is the material of the light-reflective layer, is a substance having a high reflectance with respect to a laser.
e, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, M
o, W, Mn, Re, Fe, Co, Ni, Ru, Rh,
Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, A
1, Ga, In, Si, Ge, Te, Pb, Po, S
Metals such as n and Bi and semimetals or stainless steel can be mentioned. Preferred of these are:
Cr, Ni, Pt, Cu, Ag, Au, Al and stainless steel, more preferably Ag and Au, and particularly preferably Ag. These substances may be used alone, or in combination of two or more kinds, or may be used as an alloy. The light reflecting layer can be formed on the recording layer by, for example, vapor deposition, sputtering or ion plating of the above light reflecting substance. The thickness of the light reflecting layer is generally in the range of 10 to 300 nm, preferably in the range of 50 to 200 nm.

It is preferable to provide a protective layer on the light reflecting layer for the purpose of physically and chemically protecting the recording layer and the like. Note that, in the same manner as in the case of manufacturing a DVD-R type optical information recording medium, that is, when two substrates are bonded together with the recording layer inside, it is not always necessary to provide a protective layer. Examples of the material used for the protective layer include SiO, SiO ₂ , MgF ₂ , SnO ₂ , and Si ₃ N.
_And organic substances such as thermoplastic resins, thermosetting resins, and UV curable resins. The protective layer can be formed, for example, by laminating a film obtained by extrusion of a plastic on the reflective layer via an adhesive. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating. In the case of a thermoplastic resin or a thermosetting resin, they can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying.
In the case of a UV-curable resin, it can also be formed by preparing a coating solution as it is or by dissolving it in an appropriate solvent, applying the coating solution, and irradiating with UV light to cure. Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose. The thickness of the protective layer is generally 0.1 to
It is in the range of 100 μm. Through the above steps, a laminate in which the recording layer, the light reflecting layer, and the protective layer are provided on the substrate can be manufactured.

The optical information recording method of the present invention can be performed, for example, as follows, using the above optical information recording medium. First, the optical information recording medium is set at a constant linear velocity (for the CD format, 1.
2-14 m / sec) or rotating at a constant angular speed,
A recording light such as a semiconductor laser is irradiated from the substrate side or the protective layer side. By this light irradiation, a cavity is formed at the interface between the recording layer and the reflective layer (the cavity is formed by deforming the recording layer or the reflective layer, or by deforming both layers), or the substrate is thinned. It is considered that information is recorded when the refractive index is changed due to deformation of the recording layer or discoloration of the recording layer or a change in the association state. In the present invention, a semiconductor laser having an oscillation wavelength in the range of 390 to 550 nm is used as the recording light. As a preferred light source, a blue-violet semiconductor laser having an oscillation wavelength in the range of 390 to 415 nm, a blue-green semiconductor laser having a center emission wavelength of 515 nm, and an infrared semiconductor laser having a center emission wavelength of 850 nm were halved using an optical waveguide element. A blue-violet SHG laser with a center oscillation wavelength of 425 nm is used, and a blue-violet semiconductor or an SHG laser is particularly preferable in terms of recording density. Reproduction of the information recorded as described above is performed by irradiating the semiconductor laser from the substrate side or the protective layer side while rotating the optical information recording medium at the same constant linear speed as above, and detecting the reflected light. It can be carried out.

[0060]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 The compound of the present invention was prepared as 2,2
It was dissolved in 3,3-tetrafluoropropanol to obtain a coating liquid for forming a recording layer (concentration: 1% by weight). Spiral pre-groove (track pitch: 0.
6 μm, groove width: 0.3 μm, groove depth:
0.15 μm) is spin-coated on the surface on the pre-groove side of a polycarbonate substrate (diameter: 120 mm, thickness: 0.6 mm) formed by injection molding, and a recording layer (thickness (within the pre-groove): about 120 nm) ) Formed. Next, silver is sputtered on the recording layer to a thickness of about 100 n.
m light reflection layers were formed. Further, a UV curable resin (SD318, manufactured by Dainippon Ink and Chemicals, Inc.) was applied on the light reflecting layer, and irradiated with ultraviolet rays to form a protective layer having a thickness of 7 μm. According to the above steps, the optical information recording media 1 to
10 was obtained. Optical information recording for comparison was carried out in exactly the same manner as above except that compounds A, B, C and D for comparison (the compound weight was equivalent to that of the sample of the invention) were used instead of the compound of the invention. Media C-1 to C-4 were obtained.

[Evaluation of Optical Information Recording Medium] A 14T-EFM signal was recorded on the produced optical information recording medium at a linear velocity of 3.5 m / s with a blue-violet semiconductor laser having a wavelength of 408 nm.
The recording characteristics were measured. For recording and recording characteristics evaluation, DDU1000 manufactured by Pulstec was used. Table 2 shows the compounds used for the recording layer of each sample and the evaluation results obtained.

[0063]

[Table 2]

The structural formulas of Compounds A to D used in Comparative Examples are shown below.

[0065]

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From the results shown in Table 2, the recording media 1 to 10 comprising the recording layer containing the compound of the present invention showed that Comparative Examples C
It shows higher sensitivity, higher reflectivity, and higher degree of modulation than those of Nos. 1 to 4, indicating that a high signal intensity can be obtained with high sensitivity.

[0067]

By using the bispyridinium compound of the present invention, an optical information recording medium having high reflectance, high sensitivity and high modulation can be obtained. Especially CD-R and DV
Since the above-mentioned effects are obtained by using a laser having a shorter wavelength than in the case of DR, a higher-density information recording medium and a recording / reproducing method can be provided.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Noboru Komori 2-12-1 Ogimachi, Odawara-shi, Kanagawa Prefecture Fuji Photo Film Co., Ltd. F-term (reference) 2H111 EA03 EA12 EA22 EA32 FA01 FA12 FB42 5D029 JA04 JB28 JC02 JC20

Claims (3)

[Claims] 1. An information recording medium comprising a substrate on which a recording layer capable of recording information by irradiating a laser beam having a wavelength of 550 nm or less is provided, wherein the recording layer has the following general formula (I-1): An information recording medium comprising a bispyridinium compound represented by the formula (1): Embedded image [Wherein, R ₁ and R ₂ each independently represent a substituent;
₃ and R ₄ each independently represent an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group or a heterocyclic group; R ₁ and R ₂ , R ₁ and R ₃ , R ₂ and R ₄ or R
₃ and R ₄ may be linked to each other to form a ring;
And s each independently represent an integer of 0 to 4, and when r and s are 2 or more, a plurality of R ₁ and R ₂ may be the same or different from each other. ^Xp- represents an anion, p represents an integer of 1 or more, and q represents a number necessary for balancing electric charges. ] 2. The information recording medium according to claim 1, wherein a reflection layer is provided on the recording layer. 3. The wavelength of a laser beam is 390 to 450 nm.
The information recording medium according to claim 1, wherein: