JP2003019867A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable good recording and reproduction even when a blue semiconductor laser having a short oscillation wavelength is used by using a dye having appropriate optical characteristics and chemical characteristics for a recording layer. I do. SOLUTION: In an optical recording medium having at least a recording layer capable of recording and reproducing information by a laser beam on a substrate, the recording layer contains a compound represented by the following general formula (1). . . . . General formula (1) (In the above general formula (1), ring A represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring which may have a substituent;
Represents an oxygen atom or a sulfur atom, and R _{1 to} R ₅ each independently represent a hydrogen atom or an arbitrary substituent. Where R ₁
Any two or more of R ₄ to R ₄ may combine to form a ring. )

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a write-once type optical recording medium compatible with recording / reproducing of information by blue laser light.

[0002]

2. Description of the Related Art Conventionally, as a recording medium (hereinafter referred to as an optical recording medium) for optically recording / reproducing information, a magneto-optical recording medium, a phase change recording medium, a chalcogen oxide optical recording medium,
Organic dye-based optical recording media and the like have been proposed. Among them, the organic dye-based optical recording media are considered to have superiority in that they are inexpensive and the manufacturing process is easy. There is.

At present, this organic dye-based optical recording medium has a structure in which a metal layer having high reflectance is laminated on the organic dye layer, and is a compact disc (hereinafter abbreviated as CD).
CD-R, which is a write-once optical recording medium conforming to the standard
(CD-Recordable) has been mass-produced and widely spread. However, the recording capacity of the CD-R is 0.65
Since it is only about GB, the demand for higher density and large capacity optical recording media is increasing with the dramatic increase in the amount of information.

In such an optical recording medium, a laser beam having a short wavelength is used for recording / reproducing information to record / reproduce information.
Since the beam spot of the laser light at the time of reproduction can be made small and high-density optical recording becomes possible, in recent years,
Development of a semiconductor laser having an oscillation wavelength of a shorter wavelength is in progress.

At present, an oscillation wavelength (68 nm) shorter than the wavelength (780 nm) of laser light used for CD-R is used.
Digital versatile disk (hereinafter referred to as "D") that has realized the high density recording of high density by using a red semiconductor laser of 0 nm, 650 nm, 635 nm, etc.
VD), and DVD-R (DVD-Recordable), which is an additionally recordable optical recording medium of the same standard, have already been put to practical use.

Further, a shorter oscillation wavelength (wavelength 350 nm
The development of a blue semiconductor laser, which is a laser having a wavelength of up to 530 nm), is rapidly progressing, and it is expected that higher density recording / reproduction will be possible by using this. Therefore, it is expected that the need for an optical recording medium capable of recording / reproducing with this blue semiconductor laser will increase in the future.

[0007]

A write-once type optical recording medium has a structure in which a recording layer containing a dye is formed in a thin film on a substrate. At the time of recording information, the recording layer is irradiated with high energy laser light. The dye in the recording layer absorbs this laser light to decompose and generate heat, thereby causing a physical change or a chemical change in the recording layer or the substrate, thereby forming a pit corresponding to the recorded information. On the other hand, at the time of reproducing information, this recording layer is irradiated with low energy laser light. When the laser light is reflected by the reflective film formed on the side of the recording layer opposite to the substrate, the reflectance of the laser light differs between the part where the pit is formed and the part other than that. It is common to reproduce the information corresponding to.

Here, in order to form and detect good pits, the dye used in the recording layer is required to exhibit an appropriate absorbance at the wavelength of the laser light used. As the laser light for recording / reproduction, those having almost the same wavelength are usually used, but the dye having too low absorbance at the wavelength of the laser light is difficult to be sufficiently decomposed and heated by irradiation of the laser light, It becomes difficult to form pits with sufficient sensitivity. On the other hand, dyes that have too high absorbance at this wavelength have a large effect on the pits and in the radial direction due to intense decomposition and heat generation, making reliable pit formation difficult, and irradiating sufficient laser light. Since it is not reflected by the pits, it is difficult to detect pits when reproducing information.

However, in general, CD-R and DVD-
The dye used in the R recording layer does not have optical characteristics suitable for recording / reproduction with a blue semiconductor laser having a short wavelength. When information is recorded / reproduced on / from a conventional CD-R medium or DVD-R medium using a blue semiconductor laser having a short oscillation wavelength, the refractive index of the recording layer is low and the extinction coefficient is an appropriate value. Since there is no such
Good recording / playback is not possible.

Therefore, in order to prepare an optical recording medium suitable for high density recording using a blue semiconductor laser, it is necessary to select a compound having appropriate optical characteristics as a dye used in the recording layer. is there.

Furthermore, when manufacturing an optical recording medium, it is necessary to form a recording layer containing a dye in the form of a thin film on a substrate. Therefore, the dye used in the recording layer is required to have the chemical properties that, in addition to the above-mentioned optical properties, the thin film formability in a state of being dissolved in a solvent is excellent.

According to the present invention, by using a dye having appropriate optical characteristics and chemical characteristics in the recording layer, good recording and reproduction are possible even when a blue semiconductor laser having a short oscillation wavelength is used. An object is to provide an organic dye-based optical recording medium.

[0013]

The present inventors have studied the optical and chemical properties of various organic dyes showing high sensitivity at the oscillation wavelength of blue semiconductor lasers.
The compound represented by the general formula (1) described later has excellent optical characteristics at the oscillation wavelength of the blue semiconductor laser, and also has excellent chemical characteristics at the time of layer formation. The present invention has been achieved by recognizing that it can be suitably used for a recording layer of an optical recording medium to be performed.

That is, the gist of the present invention is an optical recording medium having at least a recording layer capable of recording and reproducing information by laser light on a substrate, the recording layer being represented by the following general formula (1). An optical recording medium is characterized by containing a compound.

[Chemical 3] ． ． ． General formula (1) (In the general formula (1), ring A represents an aromatic hydrocarbon ring or an aromatic heterocycle which may have a substituent, and X
Represents an oxygen atom or a sulfur atom, and R _{1 to} R ₅ each independently represent a hydrogen atom or an optional substituent. However, R ₁
Any two or more groups of R ₄ to R ₄ may be bonded to form a ring. )

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The optical recording medium of the present invention has at least a recording layer capable of recording and reproducing information by laser light on a substrate, and this recording layer is represented by the following general formula (1) as a dye. Compound (hereinafter referred to as compound (1))
It is characterized by containing.

[0016]

[Chemical 4] ． ． ． General formula (1)

In the above general formula (1), ring A represents an aromatic hydrocarbon ring or aromatic heterocycle which may have a substituent, X represents an oxygen atom or a sulfur atom, and R ₁ ~ R ₅
Each independently represent a hydrogen atom or an optional substituent. However, any two or more groups of R _{1 to} R ₄ may be bonded to form a ring. Of these, those in which the ring A represents an aromatic hydrocarbon ring in the general formula (1) are preferable,
Further, it is preferable that X represents an oxygen atom.

In particular, the recording layer is a compound represented by the following general formula (2) (hereinafter, referred to as one embodiment of the compound (1)).
The compound (2) is preferably contained.

[Chemical 5] ． ． ． General formula (2)

First, the compound (1) and the compound (2) contained in the recording layer of the optical recording medium of the present invention will be described.

In the above general formula (1) or (2), R
_{1 to} R ₁₀ each independently represent a hydrogen atom or an optional substituent. It should be noted that any two or more groups of R _{1 to} R ₁₀ may be bonded to each other to form a ring.

As the substituent, various substituents which do not impair the characteristics of the compound (1) and compound (2) aimed at in the present invention can be selected, and specific examples are as follows. A linear or branched alkyl group having 1 to 18 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-heptyl group; cyclopropyl Group 3 to 3 carbon atoms such as cyclopentyl group, cyclohexyl group and adamantyl group
18 cyclic alkyl group; linear or branched alkenyl group having 2 to 18 carbon atoms such as vinyl group, propenyl group and hexenyl group; cyclic alkenyl group having 3 to 18 carbon atoms such as cyclopentenyl group and cyclohexenyl group; 2 -Thienyl group, 2
-Heterocyclic groups such as pyridyl group, 4-piperidyl group and morpholino group; phenyl group, tolyl group, xylyl group, mesityl group and other C6-18 aryl groups; benzyl group, phenethyl group and other aralkyl groups; methoxy Group, ethoxy group,
a linear or branched alkoxy group having 1 to 18 carbon atoms such as n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group; propenyloxy group, butenyloxy group, pentenyloxy group, etc. A linear or branched alkenyloxy group having 3 to 18 carbon atoms; methylthio group, ethylthio group, n-propylthio group, n-butylthio group, sec-butylthio group, ter
C1-C18 linear or branched alkylthio group such as t-butylthio group; halogen atom such as fluorine atom, chlorine atom, bromine atom; nitro group; cyano group; isocyano group; cyanato group; isocyanato group; thiocyanato group ; isothiocyanato group; a mercapto group; hydroxy group; a hydroxyamino group; a formyl group; a sulfonic group; a carboxyl group; -NR ₁₁ group represented by R _12, -NHCOR ₁₃
An acylamino group represented by -NHCOOR ₁₄ , a carbamate group represented by -COOR ₁₅ , a carboxylic acid ester group represented by -COOR ₁₅ , a carbamoyl group represented by -CONR ₁₆ R ₁₇ , an acyl group represented by -COR _18. , And an acyloxy group represented by OCOR ₁₉ , a sulfonyl group represented by —SO ₂ R ₂₀ , a sulfamoyl group represented by —SO ₂ NR ₂₁ R ₂₂ , and a sulfonate ester group represented by —SO ₃ R _23. ,
A sulfonamide group represented by —NHSO ₂ R ₂₄ , and the like. Of these substituents, a chain or cyclic alkyl group,
A part of the chain alkoxy group and the chain thioalkyl group may be further substituted with a substituent described below.
The position of the substituent is not particularly limited, and the number of the substituent is also 1 to 10
It is possible in the range of individual pieces. When it has a plurality of substituents, it may be the same or different.

Note that R₁₁~ R_{twenty four}As a hydrogen atom,
Optionally substituted hydrocarbon group or optionally substituted hetero group
A ring group is mentioned. Preferably R₆, R₉, R_Ten,
R₁₁, R ₁₂, R₁₅, R₁₈, R₁₉, R₂₀, R_{twenty three}, R_{twenty four}Is
Optionally substituted hydrocarbon group or optionally substituted hetero group
Represents a ring group, R₇, R₈, R₁₃, R₁₄, R₁₆, R₁₇, R
_{twenty one}, R_{twenty two}Is a hydrogen atom, an optionally substituted hydrocarbon group,
Represents any of the heterocyclic groups which may be replaced.

The hydrocarbon group represented here is a linear or branched alkyl group, a cyclic alkyl group, a linear or branched alkenyl group, a cyclic alkenyl group, an aralkyl group or an aryl group. These alkyl chain moieties may be substituted with those described below, and the aryl group moieties may be substituted with the same substituents as R _{1 to} R ₁₀ . Among these, preferred are linear or branched alkyl groups, aralkyl groups,
It is an aryl group.

Further, the heterocyclic group is a saturated heterocycle such as 4-piperidyl group, morpholino group, 2-morpholinyl group, piperazyl group, 2-furyl group, 2-pyridyl group, 2-thiazolyl group, 2-quinolyl group. It may be an aromatic heterocycle such as a group. These may contain a plurality of hetero atoms, may further have a substituent, and the bonding position is not limited. Preferred heterocycles are 5- or 6-membered saturated heterocycles, 5- or 6-membered monocycles, and their two condensed aromatic heterocycles.

In the compound (1), the ring formed by combining any two or more groups among R _{1 to} R ₄ does not impair the characteristics of the compound (1) intended in the present invention. If it is saturated or unsaturated, various ones may be mentioned, and among them, a 5- to 8-membered hydrocarbon ring or a heterocycle is preferable. The position and number of R _{1 to} R ₄ are not limited as long as they are formed by any two or more groups, but those formed by two adjacent groups are preferable. Furthermore, a part of the ring may be further substituted with a substituent described below.

Further, the substituents of the aromatic hydrocarbon ring or aromatic heterocycle represented by ring A may be bonded by any two or more adjacent groups to form a ring. As the rings, various rings can be used regardless of whether they are saturated or unsaturated as long as the characteristics of the compound (1) are not impaired, but a saturated 5- or 6-membered heterocyclic ring is preferable. Further, a part of the ring formed by these may be substituted with a substituent described later.

Further, in the compound (2), the ring formed by the bonding of any two or more groups among R _{1 to} R ₄ and R _{6 to} R ₁₀ is the compound (the object of the present invention) As long as the characteristics of 2) are not impaired, various ones may be mentioned regardless of whether they are saturated or unsaturated. Among them, R _{1 to} R ₄
If it is, a 5- to 8-membered ring is preferable, and if it is R _{6 to} R ₁₀ , a 5- or 6-membered hydrocarbon ring or a heterocycle is preferable. The position and number of R _{1 to} R ₄ and R _{6 to} R ₁₀ are not limited as long as they are formed by any two or more groups, but those formed by two adjacent groups are not limited. preferable. Furthermore,
A part of the ring may be further substituted with a substituent described below.

The compound (1) is the R in the general formula (1).
_When it does not have a ring formed by combining any two or more groups of _{1 to} R _10, the polycyclic skeleton (flavone skeleton) whose structure is represented by the general formula (1) is a compound ( As the base of 1), the compound (1) becomes a flavone compound.

On the other hand, the compound (1) has a ring formed by bonding any two or more groups among R _{1 to} R ₁₀ in the general formula (1), and the ring has the flavone skeleton. When condensed, the polycyclic skeleton represented by the following formula, for example, constitutes the matrix of compound (1).

[Chemical 6]

Of the above-mentioned examples of R _{1 to} R ₁₀ , preferred are a hydrogen atom, an optionally substituted chain or cyclic alkyl group, an optionally substituted chain alkoxy group, and an optionally substituted chain. Good chain thioalkyl group, halogen atom, nitro group, cyano group, hydroxy group, carboxyl group,-
An amino group represented by NR ₁₁ R ₁₂ , an acylamino group represented by —NHCOR ₁₃ , a carbamate group represented by —NHCOOR ₁₄ , a carboxylic ester group represented by —COOR ₁₅ , and a group represented by —CONR ₁₆ R ₁₇ . A carbamoyl group,
Examples thereof include an acyl group represented by COR ₁₈ and an acyloxy group represented by OCOR ₁₉ . It should be noted that any two or more groups of R _{1 to} R ₁₉ may be bonded to each other to form a ring. Among them, it is preferable that any two or more groups of R _{1 to} R ₁₀ are bonded to form a ring.

Among them, preferred is a hydrogen atom,
A chain alkyl group which may be substituted, a chain alkoxy group which may be substituted, a chain thioalkyl group which may be substituted, a halogen atom, a nitro group, a hydroxy group, -NR ₁₁
An amino group represented by R ₁₂ , an acylamino group represented by —NHCOR ₁₃ , a carboxylic ester group represented by —COOR ₁₅ , an acyloxy group represented by —OCOR ₁₉ , or an acyl group represented by COR _18. Is mentioned. Also R ₁ ~
Any two or more groups of R ₁₀ may combine to form an aromatic hydrocarbon ring or a saturated heterocycle. Particularly preferably, R ₅ and R ₈ are electron donating groups such as a hydroxy group and an amino group.

As described above, the ring formed by combining the chain and cyclic alkyl groups, chain alkoxy groups, chain acyl groups, aryl groups and R _{1 to} R ₁₀ further has a substituent. May be. Examples of this substituent include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, and a tert-group.
Alkoxy group having 1 to 10 carbon atoms such as butoxy group; methoxymethoxy group, ethoxymethoxy group, propoxymethoxy group, ethoxyethoxy group, propoxyethoxy group, alkoxyalkoxy group having 2 to 12 carbon atoms such as methoxybutoxy group; methoxymethoxy C3 to C15 alkoxyalkoxyalkoxy groups such as methoxy group, methoxymethoxyethoxy group, methoxyethoxymethoxy group, methoxymethoxyethoxy group, ethoxyethoxymethoxy group; allyloxy group; phenyl group, tolyl group, xylyl group, etc. 6 to 12 aryl groups (these may be partially substituted with a substituent); a phenoxy group,
Aryloxy group having 6 to 12 carbon atoms such as tolyloxy group, xylyloxy group and naphthyloxy group; alkenyloxy group having 2 to 12 carbon atoms such as allyloxy group and vinyloxy group; cyano group; nitro group; hydroxyl group; amino group; An alkylamino group having 1 to 10 carbon atoms such as N, N-dimethylamino group and N, N-diethylamino group; having 1 to 6 carbon atoms such as methylsulfonylamino group, ethylsulfonylamino group and n-propylsulfonylamino group Alkylsulfonylamino group; halogen atom such as fluorine atom, chlorine atom, bromine atom; carboxyl group; methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl and the like having 2 to 2 carbon atoms 7 alkoxycarbonyl group; methylcarbonylo Shi, ethyl carbonyloxy group,
C2-C7 alkylcarbonyloxy groups such as n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group; methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propoxycarbonyloxy group, isopropoxy Examples thereof include a carbonyloxy group and an alkoxycarbonyloxy group having 2 to 7 carbon atoms such as an n-butoxycarbonyloxy group.

In the compound (1), the ring A represents an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring or an anthracene ring, or an aromatic heterocycle such as a pyrrole ring, a furan ring, a pyridine ring or a quinoline ring. . These may have a substituent as shown in R _{1 to} R ₁₀ described above.

The preferred structure of ring A is a benzene ring or a naphthalene ring as the aromatic hydrocarbon ring, and a 5- or 6-membered monocyclic ring or two condensed rings thereof as the aromatic carbon heterocycle. Of these, particularly preferred is a benzene ring or a naphthalene ring.

In the compound (1), X represents an oxygen atom or a sulfur atom. It is preferably an oxygen atom. X
Comparing the case where is an oxygen atom and the case where it is a sulfur atom, in general, when X is an oxygen atom, the maximum absorption wavelength tends to shift to the shorter wavelength side.

The compound represented by the general formula (1) has a molecular weight of preferably 1,000 or less, particularly preferably 70.
It is a compound of 0 or less.

Preferred examples of the compound (1) include compounds represented by the following structural formulas. However, in the following structural formula, i-Pr is an isopropyl group, t-B
u represents a tert-butyl group, respectively.

[0038]

[Chemical 7]

[0039]

[Chemical 8]

[0040]

[Chemical 9]

[0041]

[Chemical 10]

[0042]

[Chemical 11]

[0043]

[Chemical 12]

Many of the compounds (1) are present in a relatively short wavelength region where the maximum absorption wavelength (λ _max ) when formed into a thin film is about 330 to 380 nm, and the peak shape of the absorption spectrum is relatively large. It has excellent optical characteristics for recording and reproducing using a blue semiconductor laser, such as being sharp and having a molar absorption coefficient of 20,000 or more. Here, the maximum absorption wavelength is usually a wavelength of 300n.
It means the maximum absorption wavelength at m or more. Further, since it is excellent in thin film formability in a state of being dissolved or dispersed in a solvent, it also satisfies the chemical characteristics required when manufacturing an optical recording medium. Therefore, the compound (1) can be used very suitably in the recording layer of the optical recording medium for recording / reproducing by using the blue semiconductor laser.

Next, the optical recording medium of the present invention will be described. The optical recording medium of the present invention comprises at least a substrate and a recording layer containing the compound (1). Furthermore,
If necessary, an undercoat layer, a reflective layer, a protective layer, etc. may be provided.

An example of a preferable layer structure is a medium having a high reflectance in which a recording layer is provided on a substrate and a reflective layer and a protective layer are further laminated in this order on the recording layer. in this case,
Information is recorded / reproduced by irradiating a laser beam from the substrate side.

The optical recording medium of the present invention will be described below by taking a medium having such a structure as an example. In the following description, for convenience of explanation, the side where the protective layer is present and the side where the substrate is present are regarded as the upper side and the lower side, respectively, and each surface of each layer corresponding to these directions is the upper surface of each layer. And the lower surface.

The substrate in the optical recording medium of the present invention may be made of various materials as long as it is basically transparent to the wavelengths of recording light and reproducing light.
Specifically, for example, acrylic resin, methacrylic resin, polycarbonate resin, polyolefin resin (particularly amorphous polyolefin), polyester resin, polystyrene resin, epoxy resin or other resin substrate, glass substrate, glass Examples thereof include a substrate on which a resin layer made of a radiation curable resin such as a photocurable resin is provided.

Of these, an injection molded polycarbonate substrate is preferable from the viewpoints of high productivity, cost, moisture absorption resistance and the like. From the viewpoint of chemical resistance and moisture absorption resistance,
Substrates made of amorphous polyolefin are preferred. Further, from the viewpoint of high-speed response, a glass substrate is preferable.

When a resin substrate is used, or when a resin layer is provided on the side in contact with the recording layer (upper side), the recording / reproducing light is recorded on the resin substrate or the upper surface of the resin layer. The guide grooves and pits may be formed. Examples of the shape of the guide groove include a concentric shape and a spiral shape with the center of the optical recording medium as a reference. When forming a spiral guide groove, the groove pitch is 0.2 to 1.2.
It is preferably about μm.

A recording layer containing the compound (1) is formed directly on the substrate or on an undercoat layer or the like provided on the substrate, if necessary. Examples of the method for forming the recording layer include various commonly used thin film forming methods such as a vacuum vapor deposition method, a sputtering method, a doctor blade method, a casting method, a spin coating method and a dipping method. From the viewpoint of mass productivity and cost, the spin coating method is preferable, and from the viewpoint of obtaining a recording layer having a uniform thickness, the vacuum vapor deposition method or the like is preferable to the coating method. In the case of film formation by the spin coating method, the rotation speed is preferably 500 to 15000 rpm. In some cases, heating is performed after spin coating,
You may perform processing, such as applying to solvent vapor.

When the recording layer is formed by a coating method such as a doctor blade method, a casting method, a spin coating method, or a dipping method, the coating solvent used for dissolving the compound (1) and coating it on the substrate is There is no particular limitation as long as it is a solvent that does not corrode. Specifically, for example, a ketone alcohol solvent such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; a cellosolve solvent such as methyl cellosolve and ethyl cellosolve; n-hexane,
Chain hydrocarbon solvents such as n-octane; cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t
cyclic hydrocarbon solvents such as ert-butylcyclohexane and cyclooctane; perfluoroalkyl alcohol solvents such as tetrafluoropropanol, octafluoropentanol, and hexafluorobutanol; methyl lactate, ethyl lactate, methyl 2-hydroxyisobutyrate, etc. Examples thereof include hydroxycarboxylic acid ester solvents.

When the vacuum vapor deposition method is used, for example, the compound (1) and, if necessary, recording layer components such as other dyes and various additives are put in a crucible placed in a vacuum container, The inside of this vacuum vessel is 10 ^-2 to 10 with an appropriate vacuum pump.
After evacuating to about ⁻⁵ Pa, the crucible is heated to evaporate the components of the recording layer and vapor-deposited on the substrate placed facing the crucible to form the recording layer.

In addition to the compound (1), a transition metal chelate compound (for example, acetylacetonate chelate, bisphenyldithiol chelate) as a singlet oxygen quencher is added to the recording layer in order to improve stability and light resistance. , Salicylaldehyde oxime, bisdithio-α-diketone, etc.) and a recording sensitivity improver such as a metal compound for improving recording sensitivity. Here, the metal-based compound refers to a compound in which a metal such as a transition metal is contained in the compound in the form of atoms, ions, clusters, etc., and examples thereof include ethylenediamine-based complexes, azomethine-based complexes, phenylhydroxyamine-based complexes, and phenanthroline-based complexes. , Dihydroxyazobenzene-based complexes, dioxime-based complexes, nitrosoaminophenol-based complexes, pyridyltriazine-based complexes, acetylacetonate-based complexes, metallocene-based complexes, and porphyrin-based complexes. The metal atom is not particularly limited, but a transition metal is preferable.

If necessary, a plurality of kinds of compounds (1) may be used in combination in the recording layer. Furthermore, in the recording layer,
In addition to the compound (1), dyes of other systems can be used in combination, if necessary. The other type of dye is not particularly limited as long as it has a suitable absorption mainly in the oscillation wavelength range of the recording laser. Further, it is used for CD-R and the like, a dye suitable for recording / reproducing using a near infrared laser having an oscillation wavelength in the wavelength band of 770 to 830 nm, and used for DVD-R and the like, the wavelength of 620 to 690 nm. A plurality of types of laser light belonging to different wavelength bands were used by incorporating a dye or the like suitable for recording / reproduction using a red laser having an oscillation wavelength in the band into the recording layer in combination with the compound (1). It is also possible to manufacture an optical recording medium compatible with recording and reproduction.

Examples of dyes other than the compound (1) include metal-containing azo dyes, benzophenone dyes, phthalocyanine dyes, naphthalocyanine dyes, cyanine dyes, azo dyes, squarylium dyes and metal-containing indo dyes. Aniline dye, triarylmethane dye, merocyanine dye, azurenium dye, naphthoquinone dye, anthraquinone dye, indophenol dye,
Examples include xanthene dyes, oxazine dyes, pyrylium dyes, and the like.

Furthermore, if necessary, a binder, a leveling agent, an antifoaming agent and the like can be used in combination. Preferred binders include polyvinyl alcohol, polyvinylpyrrolidone, nitrocellulose, cellulose acetate, ketone resins, acrylic resins, polystyrene resins, urethane resins, polyvinyl butyral, polycarbonate, polyolefins and the like.

The film thickness of the recording layer is not particularly limited because the suitable film thickness depends on the recording method and the like, but it is usually 50 to 300 nm.

A reflective layer is formed on the recording layer. The film thickness is preferably 50 to 300 nm.

The material of the reflective layer is a material having a sufficiently high reflectance at the wavelength of the reproduction light, such as Au, Al,
Metals such as Ag, Cu, Ti, Cr, Ni, Pt, Ta and Pd can be used alone or as an alloy.
Among these, Au, Al, and Ag have a high reflectance and are suitable as a material for the reflective layer. In addition to these metals as the main component, other materials may be contained in addition to them. Here, the main component means one having a content rate of 50% or more. Examples of materials other than the main component include Mg, Se, and H
f, V, Nb, Ru, W, Mn, Re, Fe, Co, R
h, Ir, Cu, Zn, Cd, Ga, In, Si, G
Mention may be made of metals and semi-metals such as e, Te, Pb, Po, Sn and Bi. Among them, those containing Ag as a main component are particularly preferable because they are low in cost, are likely to have a high reflectance, and have a beautiful background color when a print receiving layer described later is provided. For example, Ag for Au,
AgPdCu alloy containing 0.1 to 5 atomic% of one or more selected from Pd, Pt, Cu and Nd, A
gCuAu alloy, AgCuAuNd alloy, AgCuNd
Alloys and the like are preferable because they have high reflectance, high durability, high sensitivity, and low cost. As a material other than metal, it is also possible to alternately stack low-refractive index thin films and high-refractive index thin films to form a multilayer film, and use this as a reflective layer.

As a method of forming the reflective layer, for example,
A sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method and the like can be mentioned. Further, a known inorganic or organic intermediate layer or adhesive layer may be provided on the substrate or below the reflective layer in order to improve reflectance, recording characteristics, adhesion, and the like.

The material of the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. Examples of the material of the organic substance include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, a UV curable resin and the like. Further, as inorganic substances, SiO ₂ , Si ₃
N _4, MgF _2, SnO ₂ and the like.

When a thermoplastic resin, a thermosetting resin or the like is used, a protective layer can be formed by coating a coating solution prepared by dissolving in a suitable solvent on the reflecting layer and drying. . When a UV curable resin is used, it can be applied on the reflective layer as it is, or by applying a coating solution prepared by dissolving it in a suitable solvent onto the reflective layer and irradiating it with UV light to cure it. A protective layer can be formed.
As the UV curable resin, for example, an acrylate resin such as urethane acrylate, epoxy acrylate, polyester acrylate can be used. These materials may be used alone or in combination of two or more. The protective layer may be formed as a single layer or a multilayer.

As the method for forming the protective layer, similar to the recording layer, a coating method such as a spin coating method or a casting method, or a method such as a sputtering method or a chemical vapor deposition method can be used, but the spin coating method is preferable. The thickness of the protective layer is generally in the range of 0.1 to 100 μm, but in the present invention, it is preferably 3 to 30 μm.

As described above, as the layer structure of the optical recording medium, the substrate,
Although the structure in which the recording layer, the reflective layer, and the protective layer are laminated in this order has been described as an example, other layer structures may be adopted as described above.

For example, another substrate may be attached to the upper surface of the protective layer in the layer structure of the above example, or to the upper surface of the reflective layer by omitting the protective layer from the layer structure of the above example. The substrate at this time may be the substrate itself without any layer provided, or may have an arbitrary layer on the bonding surface or the opposite surface. Similarly, two optical recording media having the layer structure of the above example or an optical recording medium in which the protective layer is omitted from the layer structure of the above example are provided with the upper surfaces of the respective protective layers and / or reflective layers facing each other. You may stick together.

Further, as an example of a preferable layer structure of the optical recording medium of the present invention, there is a medium in which a reflective layer is provided on a substrate, and a recording layer and a protective coating are further laminated in this order. In this case, laser light is irradiated through the protective film to record / reproduce information.

The protective coating may be a film or sheet which may be laminated with an adhesive, or a material similar to that of the above-mentioned protective layer may be used and a coating liquid for film formation may be applied and cured or dried. You may form by this. The thickness of the protective coating is usually about 0.1 μm to 300 μm, preferably about 0.1 μm to 200 μm.

Also in such a layer structure, each layer such as the recording layer and the reflection layer can be usually the same as described above.
However, in this layer structure, the substrate does not need to be transparent, and therefore, in addition to the materials described above, an opaque resin, ceramic,
A substrate made of metal (including alloy) or the like can be used.

Also in such a layer structure, any layers may be provided between the above-mentioned layers as needed, as long as the characteristics of the present invention are not impaired.

By the way, as one means for increasing the recording density of the optical recording medium, there is increasing the numerical aperture of the objective lens. This makes it possible to miniaturize the light spot focused on the information recording surface.

On the other hand, if the numerical aperture of the objective lens is increased, when a laser beam is irradiated for recording / reproducing, the aberration of the light spot due to the warp of the optical recording medium is apt to be large, so that good recording is possible. The reproduced signal may not be obtained stably.

In order to reduce such aberrations, it is preferable to use the optical recording medium having a basic layer structure consisting of the substrate, the reflection layer, the recording layer and the thin protective film, and to record / reproduce through the protective film. .

Alternatively, in an optical recording medium having a basic layer structure consisting of a transparent substrate, a recording layer, a reflective layer and a protective layer, the thickness of the transparent substrate through which the recording / reproducing laser beam passes is 50 to 30.
It is preferable to reduce the thickness to about 0 μm.

After the formation of the other layers, an ultraviolet curable resin layer or an inorganic thin film is formed on the incident surface of the recording / reproducing laser beam (usually the lower surface of the substrate) for the purpose of protecting the surface and preventing adhesion of dust and the like. May be formed into a film, and the surface is not the incident surface of the recording / reproducing laser beam (usually the upper surface of the reflective layer or protective layer).
In addition, a print receiving layer that can be filled in and printed by using various printers such as inkjet and thermal transfer, or various writing instruments may be provided.

In the optical recording medium of the present invention, the laser light used for recording / reproducing information is preferably shorter in wavelength from the viewpoint of realizing high-density recording, but the wavelength of 3 is particularly preferable.
Laser light of 50 to 530 nm is preferable. As typical examples of such laser light, center wavelengths of 405 nm and 410 n
m, 515 nm laser light can be mentioned.

The laser light of 350 to 530 nm is 40
It can be obtained by using a high-power semiconductor laser of 5 nm, 410 nm blue, or 515 nm blue-green. In addition, for example, (a) the fundamental oscillation wavelength is 740.
˜960 nm continuous oscillating semiconductor laser, and (b) a solid-state laser that is excited by the semiconductor laser and has a fundamental oscillating wavelength of 740 to 960 nm continuous oscillating laser light.
It can also be obtained by wavelength conversion according to G).

The above SHG may be any piezoelectric element that lacks inversion symmetry, but KDP,
ADP, BNN, KN, LBO, compound semiconductor and the like are preferable. As a specific example of the second harmonic, the fundamental oscillation wavelength is 8
In the case of a 60 nm semiconductor laser, it is 430 nm, which is a harmonic of the fundamental oscillation wavelength, and in the case of a solid-state laser excited by a semiconductor laser, Cr-doped LiSrA.
4 of harmonics from 1F ₆ crystal (fundamental oscillation wavelength 860 nm)
30 nm etc. are mentioned.

When information is recorded on the optical recording medium of the present invention, the recording layer (usually from the substrate side through the substrate) is normally focused to about 0.4 to 0.6 μm. Irradiate the laser light. The portion of the recording layer irradiated with laser light undergoes thermal deformation such as decomposition, heat generation, and dissolution by absorbing the energy of the laser light, so that the optical characteristics change. When the recorded information is reproduced, the recording layer is irradiated with laser light having a lower energy (usually from the same direction as during recording).
In the recording layer, information is reproduced by reading the difference between the reflectance of the portion where the optical characteristics have changed (that is, the portion where information has been recorded) and the reflectance of the portion where no change has occurred. Be done.

[0080]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1

[Chemical 13]

3-hydroxyflavone represented by the above structural formula [I] (manufactured by Tokyo Chemical Industry Co., Ltd.-λ in ethanol)
_max = 344 nm, molar extinction coefficient 1.7 × 10 ⁴ )
It was dissolved in propyl lactate and adjusted to 1.0% by weight. The solution prepared by filtering this is dropped on a substrate made of an injection-molded polycarbonate resin having a diameter of 120 mm and a thickness of 0.6 mm, and the solution is applied by a spinner method, and then 100 ° C.
And dried for 30 minutes. The maximum absorption wavelength (λ
_max ) was 346.5 nm. 1 and 2 each contain 5 mg / l of the dye represented by the structural formula [I].
The absorption spectrum in an ethanol solution and a coating film is shown.

Example 2

[Chemical 14]

Fisetin represented by the above structural formula [II] (manufactured by Tokyo Kasei Co., Ltd.-λ _{max in} ethanol = 364.5)
nm, molar extinction coefficient 2.3 × 10 ⁴ ) was dissolved in propyl lactate and adjusted to 1.0 wt%. The solution prepared by filtering this was dropped on an injection molded polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λ _max ) of this coating film is 369n.
It was m.

Example 3

[Chemical 15]

Morin hydra represented by the above structural formula [III]
te (manufactured by Aldrich. λ _max = 36 in ethanol)
6.5 nm, molar extinction coefficient 1.1 × 10 ⁴ ) was dissolved in methyl lactate and adjusted to 1.0 wt%. The solution prepared by filtering this is 120 mm in diameter and 0.6 m in thickness.
m was dropped on an injection-molded polycarbonate resin substrate, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λ _max ) of this coating film is 374 n
It was m.

Example 4

[Chemical 16]

Quercetin represented by the above structural formula [IV]
(Tokyo Kasei Co., Ltd.-λ _{max in} ethanol = 375
nm, molar extinction coefficient 1.9 × 10 ⁴ ) was dissolved in diacetone alcohol to adjust to 2.0% by weight. The solution produced by filtering this is 120 mm in diameter and 1.2 m in thickness.
m was dropped on a substrate made of an injection-molded polycarbonate resin, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λ _max ) of this coating film is 3
It was 75 nm. 3 and 4 show the above structural formula [IV].
5 shows absorption spectra of the dye represented by the above in a 5 mg / l ethanol solution and a coating film, respectively.

Example 5

[Chemical 17]

30 g of potassium hydroxide and 50 m of methanol
2-hydroxyacetophenone 2.7 represented by the above structural formula [V] while being dissolved in 25 ml of 1 + water and stirred.
2 g and 4.08 g of p-anisaldehyde represented by the above structural formula [VI] were added dropwise. The reaction solution was stirred at room temperature for 2 days and then poured into a solution of 32 g of acetic acid / 300 ml of water to precipitate a solid. The precipitated solid was separated by filtration, recrystallized with ethanol, and dried under reduced pressure, and the following structural formula [VI
4.42 g of the compound represented by [I] was obtained (yield 86.9).
%).

[0091]

[Chemical 18]

Then, 3 g of potassium hydroxide was dissolved in 30 ml of dimethyl sulfoxide + 12 ml of water, and 2.54 g of the above compound [VII] was dissolved in this solution, and the mixture was cooled to 0 ° C. in an ice bath. Then add 31% hydrogen peroxide to this solution.
12 ml of the aqueous solution was slowly added dropwise, and the mixture was stirred for 7.5 hours while returning to room temperature. The reaction solution is acetic acid 15 ml / water 150
It was poured into ml to precipitate a solid, which was separated by filtration, washed with water, and dried under reduced pressure to obtain 2.03 g of a compound represented by the following structural formula [VIII] (yield 75.7%).

[0093]

[Chemical 19]

The compound represented by the above structural formula [VIII] (λ _max = 355 nm in ethanol, molar absorption coefficient: 2.1 × 10 ⁴ ) was dissolved in methyl lactate to obtain 1.0% by weight.
Adjusted to. The diameter of the dissolved solution prepared by filtering this is 12
After being dropped on a substrate made of injection-molded polycarbonate resin having a thickness of 0 mm and a thickness of 1.2 mm and applied by a spinner method,
It was dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λ _max ) of this coating film was 355.5 nm.

Example 6 A compound represented by the following structural formula [IX] was obtained by the same synthetic method as in Example 5 except that p-dimethylaminobenzaldehyde was used instead of p-anisaldehyde.

[0096]

[Chemical 20]

The compound represented by the above structural formula [IX] (λ _max = 408 nm in ethanol, molar extinction coefficient: 2.
8 × 10 ⁴ ) was dissolved in 3-hydroxy-3-methyl-2-butanone and adjusted to 1.0% by weight. A solution obtained by filtering this was dropped on a substrate made of an injection molded polycarbonate resin having a diameter of 120 mm and a thickness of 1.2 mm, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λ _max ) of this coating film is 410.5.
was nm.

In Examples 1 to 6 above, a silver film, for example, is formed on the coating film by a sputtering method or the like to form a reflection layer, and then, for example, an ultraviolet curable resin is spin-coated or the like. An optical recording medium can be prepared by coating and curing by UV irradiation to form a protective layer. This optical recording medium has a central wavelength of 4 from the value of λ _max of the coating film.
It is apparent that recording / reproducing with a semiconductor laser of 05 to 410 nm is possible.

[0099]

According to the optical recording medium of the present invention, a substance exhibiting excellent optical characteristics at the oscillation wavelength of a blue semiconductor laser and excellent chemical characteristics at the time of layer formation is used as a dye for the recording layer. Therefore, good recording and reproduction can be performed even when a blue semiconductor laser having a short oscillation wavelength is used.

[Brief description of drawings]

FIG. 1 is an absorption spectrum of a dye represented by the structural formula [I] used in Example 1 in a 5 mg / l ethanol solution.

FIG. 2 is an absorption spectrum of a coating film of the dye represented by the structural formula [I] used in Example 1.

FIG. 3 is an absorption spectrum of a dye represented by the structural formula [IV] used in Example 4 in a 5 mg / l ethanol solution.

FIG. 4 is an absorption spectrum of a dye represented by the structural formula [IV] used in Example 4 in a coating film.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiro Kameyama             1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa             Within Mitsubishi Chemical Corporation F term (reference) 2H111 EA03 EA12 EA22 EA48 FB42                 4H056 DD04 DD06 DD07 DD12 DD15                       DD16 DD19 DD23 DD29 DD30                       EA13 EA14 EA16 FA06                 5D029 JA04 JB47

Claims (8)

[Claims] 1. An optical recording medium having at least a recording layer capable of recording and reproducing information by laser light on a substrate, wherein the recording layer contains a compound represented by the following general formula (1). An optical recording medium characterized by: [Chemical 1] ． ． ． General formula (1) (In the general formula (1), ring A represents an aromatic hydrocarbon ring or an aromatic heterocycle which may have a substituent, and X
Represents an oxygen atom or a sulfur atom, and R _{1 to} R ₅ each independently represent a hydrogen atom or an optional substituent. However, R ₁
Any two or more groups of R ₄ to R ₄ may be bonded to form a ring. ) 2. The optical recording medium according to claim 1, wherein ring A in the general formula (1) represents an aromatic hydrocarbon ring. 3. The optical recording medium according to claim 1, wherein in the general formula (1), X represents an oxygen atom. 4. The optical recording medium according to claim 1, wherein the recording layer contains a compound represented by the following general formula (2). [Chemical 2] ． ． ． General formula (2) (In the general formula (2), R _{1 to} R ₁₀ each independently represent a hydrogen atom or any substituent. Provided that any two or more of R _{1 to} R ₁₀ are They may combine with each other to form a ring.) 5. In the general formula (1) or (2),
R _{1 to} R ₁₀ are each independently a hydrogen atom, an optionally substituted chain or cyclic alkyl group, an optionally substituted chain alkoxy group, an optionally substituted chain thioalkyl group, a halogen atom, a nitro group , Cyano group, hydroxy group, carboxyl group, amino group represented by —NR ₁₁ R ₁₂ , —NHCO
An acylamino group represented by R ₁₃ , a carbamate group represented by —NHCOOR ₁₄ , a carboxylic acid ester group represented by —COOR ₁₅ , a —CONR ₁₆ a carbamoyl group represented by R ₁₇ , and a represented by —COR _18. Acyl group, and -OCO
Any of the acyloxy groups represented by R ₁₉ (provided that R is
_{11 to} R ₁₉ each independently represent a hydrogen atom, an optionally substituted hydrocarbon group, or an optionally substituted heterocyclic group. Further, any two or more groups of R _{1 to} R ₁₉ may be bonded to each other to form a ring. ) Is represented, The optical recording medium of any one of Claims 1-4 characterized by the above-mentioned. 6. In the general formula (1) or (2),
R _{1 to} R ₁₀ are each independently a hydrogen atom, an optionally substituted chain or cyclic alkyl group, an optionally substituted chain alkoxy group, an optionally substituted chain thioalkyl group, a halogen atom, a nitro group , Cyano group, hydroxy group, carboxyl group, amino group represented by —NR ₁₁ R ₁₂ , —NHCO
An acylamino group represented by R ₁₃ , a carbamate group represented by —NHCOOR ₁₄ , a carboxylic acid ester group represented by —COOR ₁₅ , a —CONR ₁₆ a carbamoyl group represented by R ₁₇ , and a represented by —COR _18. Acyl group, and -OCO
Any of the acyloxy groups represented by R ₁₉ (provided that R is
₁₃ , R ₁₄ , R ₁₅ , R ₁₈ , and R ₁₉ each independently represent a hydrocarbon group which may be substituted or a heterocyclic group which may be substituted, and R ₁₁ , R ₁₂ , R ₁₆ , R ₁₇ Each independently represent a hydrogen atom, an optionally substituted hydrocarbon group, or an optionally substituted heterocyclic group. Further, any 2 of R _{1 to} R ₁₀
The above groups may be bonded to each other to form a ring. ) Is represented, The optical recording medium of any one of Claims 1-4 characterized by the above-mentioned. 7. In the general formula (1) or (2),
R _{1 to} R ₁₀ are each independently a hydrogen atom, a chain alkyl group which may be substituted, a chain alkoxy group which may be substituted,
A chain thioalkyl group which may be substituted, a halogen atom,
Nitro group, hydroxy group, an amino group represented by -NR ₁₁ R _12, an acylamino group represented by -NHCOR _13, -C
Carboxylate group represented by OOR ₁₅ , -OCOR
Any of an acyloxy group represented by ₁₉ and an acyl group represented by -COR ₁₈ (provided that any two or more groups among R _{1 to} R ₁₀ are bonded to each other to form an aromatic hydrocarbon ring or a saturated hydrocarbon group). 7. The optical recording medium according to claim 6, which represents a heterocycle). 8. The optical recording medium according to any one of claims 1 to 7, wherein information can be recorded and reproduced by a laser beam selected from a wavelength range of 350 nm to 530 nm.