JPH10157301A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high density optical recording medium capable of providing excellent recording property when a small pit is formed, by specifying a pitch of a groove of a substrate and the width of the groove, and using an azo compound to be expressed by a specified formula or its metal complex as a coloring matter to be contained in a recording layer. SOLUTION: An optical recording medium such as DVD comprises a recording layer and a reflecting layer on a transparent substrate with a groove. When a diameter of a record beam to be expressed by λ/NA (wherein λ represents a record wavelength and NA represents a numerical aperture of an objective lens) is (r), the pitch of the groove of the substrate is P(μm), and the width of the groove is Wg(μm), Wg and P are decided so as to satisfy an expression 0.24r<=Wg<=0.35r and 0.68r<=P<=0.83r. For a coloring matter to be contained in the recording layer, an azo compound to be expressed by a separately described general formula or its metal complex is used. In the formula, R1 and R2 represent a hydrogen atom and an alkyl group, R3 -R7 represent a hydrogen atom and a halogen atom, X represents a sulfur atom and the like, and Y represents a nitrogen atom and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium having a recording layer containing a dye and a reflective layer on a transparent substrate, and more particularly to an optical recording medium capable of recording at high density.

[0002]

2. Description of the Related Art A recordable optical recording medium in which a dye is used as a recording layer and a metal reflective layer is provided on the recording layer in order to increase the reflectance is disclosed in, for example, Optical Data Storage 1989.
Technical Digest Series Vol. 1, 45 (1989), a medium using a cyanine dye or a phthalocyanine dye in the recording layer is marketed as a CD-R medium.

[0003] These media can be recorded with a 780 nm semiconductor laser, and a commercially available CD player or CD-RO equipped with a 780 nm semiconductor laser is used.
It has the feature that it can be played on M players.

[0004] However, these media have a capacity of only about 650 MB, and when recording large-capacity information such as digital moving pictures, the recording time is as short as 15 minutes or less. In addition, if the size of the conventional medium is reduced in order to cope with a situation where the size of the device is reduced, the capacity becomes insufficient. The conventional CD-R described above
Recording and reproduction were performed using a semiconductor laser having a wavelength of about 780 nm as a medium.
Semiconductor lasers have been developed for higher density recording and / or
Or the reproduction became possible. At present, an optical recording medium that records a high-quality moving image of about 2 hours on a medium having a diameter of 120 mm,
It has been developed as a DVD. However, this medium has a recording capacity of 4.7 GB / side, but is a read-only medium made by transferring pits to a substrate. for that reason,
There is a need for a recordable optical recording medium having a large capacity close to the recording capacity of a read-only DVD as described above.

Generally, to increase the recording capacity of a recordable medium, the recording laser beam may be reduced. As the wavelength of the laser used is shorter and the numerical aperture (NA) of the objective lens is larger, the beam diameter becomes smaller, which is preferable for high-density recording. There is a limit. For example, the beam diameter of the DVD is not small compared to the conventional CD in comparison with the recording density. Therefore, pits smaller than the beam diameter must be accurately formed at the time of recording as compared with the case of CD-R. However, as the size of the pits becomes smaller, there arises a problem that thermal interference and crosstalk between the pits at the time of recording become larger, the degree of modulation of the shortest pit becomes smaller, and the jitter and error rate become larger. Therefore, there is a demand for a medium that can accurately form thin and small pits without sacrificing the degree of modulation during recording.

Optical recording media using a metal complex of an azo compound having a nitrogen-containing heterocycle as a recording layer are disclosed in Japanese Patent Publication Nos. 5-67438 and 07-71868. However, it does not disclose the heterocycle used in the present invention, but only describes recording at a conventional near-infrared laser wavelength, but does not disclose various conditions for increasing the recording capacity. Not.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide good recording characteristics when a smaller pit is formed than in the prior art, in which crosstalk is small even if the track pitch is reduced with respect to the recording beam diameter. An object of the present invention is to provide a high-density optical recording medium.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and have found that the recording beam diameter,
The present invention was completed by making non-trivial choices for track pitch, groove shape and dye.

That is, the present invention relates to a recording layer containing a dye absorbing laser light, directly or through another layer, on a transparent substrate having a groove, In an optical recording medium having a metal reflective layer via a layer, the diameter of a recording beam represented by λ / NA is represented by r [where λ is a recording wavelength (μm), N
A represents the numerical aperture of the objective lens], when the groove pitch (track pitch) of the substrate is P (μm), and the width of the groove is Wg (μm), Wg and P satisfy the following expressions: .24r ≦ Wg ≦ 0.35r 0.68r ≦ P ≦ 0.83r and the dye contained in the recording layer is an azo compound represented by the following formula (1) or a metal complex thereof. A high-density optical recording medium,

[0010]

Embedded image [Wherein, R ₁ and R ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfone group, a sulfonamide group, an amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted Acyl group, substituted or unsubstituted alkylcarboxyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted alkylcarbonylamino group, substituted or unsubstituted alkylsulfonamino group, substituted or unsubstituted alkylamino group, substituted Or an unsubstituted alkylsulfone group,
Represents a substituted or unsubstituted alkenyl group (here, when forming a metal complex, one of R ₃ and R ₅ is a hydroxy group, a carboxyl group, an amino group, a substituted or unsubstituted alkyl carboxyl group, Or an unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonamino group, a substituted or unsubstituted alkylamino group, and the other is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfonamide group, an amino group A substituted or unsubstituted aryl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted alkylcarboxyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkyl Sulfonamino group, substituted or unsubstituted alkylamino group, Is an unsubstituted alkylsulfone group,
Represents a substituted or unsubstituted alkenyl group. ), R ₁ and R
₄ , R ₂ and R ₆ and R ₁ and R ₂ may form a ring via a linking group, and R ₇ is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfone group, a sulfonamide group, an amino group. Group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryl group, substituted or unsubstituted acyl group, substituted or unsubstituted alkylcarboxyl group, substituted or unsubstituted aralkyl group A substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted alkylsulfone group, a substituted or unsubstituted alkenyl group, a cyano group, Nitro, mercapto, thiocyano, chlorosulfone, substituted or unsubstituted alkylthio, substituted or unsubstituted Alkyl azomethine group, a substituted or unsubstituted alkyl amino sulfone group, X
Represents a sulfur atom or N—R ₈ (where R ₈ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group,
Represents a substituted or unsubstituted alkenyl group. ), Y represents a nitrogen atom or C—R ₉ (where R ₉ has the same meaning as R ₇ ). However, when X is a sulfur atom, Y is a nitrogen atom, and when X is N—R ₈ , Y is C—R ₉ . The dye contained in the recording layer is represented by the following formula (2):
A high-density optical recording medium according to the above, which is a metal complex of an azo compound represented by

[0011]

Embedded image [Wherein R ₁ , R ₂ , R ₄ , R ₅ and R ₆ have the same meaning as in formula (1), R ₈ represents a hydroxy group or a carboxyl group, and R ₉ represents a hydrogen atom or a halogen atom. Represent. Λ is 0.630 to 0.655 μm and NA is 0.60
The high-density optical recording medium according to or described above, wherein ± 0.05.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical recording medium of the present invention comprises a recording layer containing a dye absorbing at least laser light on a transparent substrate, and a metal reflective layer. This enables high-density recording with reduced crosstalk without sacrificing the degree of modulation even if the track pitch is reduced. One example of a sectional view of the optical recording medium of the present invention is shown in FIG. 1 and FIG. As shown in FIG. 1, a four-layer structure in which a substrate 1, a recording layer 2, a reflective layer 3, and a protective layer 4 are sequentially laminated, or a substrate 1 ', a recording layer 2', and a reflective layer as shown in FIG. Some have a structure in which a layer 3 'is sequentially laminated, and a substrate 5' is bonded thereon via an adhesive layer 4 '.

When a dye is used for the recording layer, the recording layer can be formed by spin coating. When a recording layer is formed by a spin coating method on a substrate having a groove,
The thickness of the recording layer in the groove portion is usually larger than the thickness of the recording layer in the portion between the grooves (lands).

Usually, the recording sensitivity depends on the thickness of the recording layer.
Especially in the case of a medium provided with a metal reflective layer on the recording layer,
Heat is diffused into the reflective layer and the recording sensitivity is reduced. The smaller the thickness of the recording layer, the greater the influence of this thermal diffusion, and the lower the sensitivity. That is, a large difference occurs in the recording sensitivity between the groove and the land. Therefore, a thin pit can be formed even if the beam diameter of the recording laser beam is large, and recording with small crosstalk can be performed.

However, no matter how thin pits can be recorded, the track pitch cannot be reduced.
This is because, even if the track pitch is reduced indefinitely, if the diameter of the laser beam at the time of reproduction is large, not only the degree of modulation becomes small, but also the crosstalk becomes too large to make reproduction possible. Crosstalk is related to the beam diameter and track pitch during reproduction, and the width of the recorded pits.Because the beam diameter during recording and reproduction is usually the same, the track pitch should be reduced and the narrow pits should be used. This is because even when recording with small crosstalk can be performed, crosstalk increases during reproduction.

In the present invention, λ / NA [λ is the recording wavelength (μm), and NA is the numerical aperture of the objective lens, in order to reduce the crosstalk without sacrificing the degree of modulation at the time of reproduction. Let r be the recording beam diameter represented by the following expression: pitch of the groove of the substrate (track pitch) (P)
From 0.68r to 0.83r, and the width of the groove (W
g) is preferably from 0.24r to 0.35r. Here, the width of the groove means a half width. If the track pitch is less than 0.68r, the crosstalk becomes too large and the modulation is small, and the jitter and error rate are undesirably large. If it exceeds 0.83r, the radial recording density is large. And the desired recording capacity cannot be obtained. On the other hand, if the width of the groove is less than 0.24r, the degree of modulation is small, and if it exceeds 0.35r, the crosstalk is undesirably large.

The beam diameter at the time of recording and reproduction in the present invention becomes smaller as the wavelength of the laser used becomes shorter and the numerical aperture (NA) of the objective lens becomes larger, which is preferable for high-density recording. As a high-output laser usable for recording, a semiconductor laser of 0.630 to 0.655 μm is preferable, and 0.630 to 0.640 μm Is most preferred. Further, the NA of the lens is 0.60 ± 0.05 from the viewpoint of thickness unevenness of the substrate and aberration due to the inclination of the substrate.

The transparent substrate used in the optical recording medium of the present invention preferably has a transmittance of light for recording and reading signals of 85% or more and a small optical anisotropy. For example, a known resin substrate such as an acrylic resin, a polycarbonate resin, and a polyolefin resin may be used.

These substrates may be plate-shaped or film-shaped, and may be circular or card-shaped. The surfaces of these substrates have grooves and / or pits indicating recording positions. Such grooves and pits are preferably provided at the time of molding the substrate, but may also be provided by providing an ultraviolet curable resin layer on the substrate. Although the track (groove) pitch and the groove width are described above, the groove depth is preferably about 70 to 180 nm.

In the present invention, the recording layer contains a dye, and the dye used in the recording layer is one of the important factors for obtaining good recording sensitivity, reflectance and modulation. Among them, the characteristics of the dye species are particularly effective for the degree of modulation. In high-density recording, a dye having a large modulation degree when pits of the same size are formed and having excellent threshold characteristics is particularly preferable. From this point, the dye is represented by the above formula (1). An azo compound, a metal complex of the compound, and a metal complex of the compound represented by the formula (2) are preferable.

In the substituents of formulas (1) and (2), the halogen atom is fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine.

The substituted or unsubstituted alkyl group includes
Linear, branched or cyclic alkyl group, alkoxyalkyl group, alkoxyalkoxyalkyl group, alkoxyalkoxyalkoxyalkyl group, alkoxycarbonylalkyl group, alkoxycarbonyloxyalkyl group,
Alkoxyalkoxycarbonyloxyalkyl group, hydroxyalkyl group, hydroxyalkoxyalkyl group, hydroxyalkoxyalkoxyalkyl group, cyanoalkyl group, acyloxyalkyl group, acyloxyalkoxyalkyl group, acyloxyalkoxyalkoxyalkyl group, halogenated alkyl group, sulfonealkyl group, It is selected from an alkylcarbonylaminoalkyl group, an alkylsulfonaminoalkyl group, a sulfonamidoalkyl group, an alkylaminoalkyl group, an aminoalkyl group, and an alkylsulfonalkyl group.

Here, the straight-chain, branched or cyclic alkyl group is a hydrocarbon group having 1 to 15 carbon atoms. Considering the workability by coating on a polycarbonate, acrylic, epoxy, polyolefin substrate or the like, methyl is preferred. Group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-
Butyl, t-butyl, n-pentyl, iso-pentyl, 2-methylbutyl, 1-methylbutyl, neo-pentyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, cyclo -Pentyl, n-hexyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3,3-dimethylbutyl, 2,3-dimethylbutyl, 1 , 3-dimethylbutyl, 2,2-dimethylbutyl, 1,2-dimethylbutyl, 1,1-dimethylbutyl, 3-
Ethylbutyl, 2-ethylbutyl, 1-ethylbutyl, 1,2,2-trimethylbutyl, 1,1,2-trimethylbutyl, 1-ethyl-2-methylpropyl, cyclo-hexyl, n- Heptyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2,
4-dimethylpentyl group, n-octyl group, 2-ethylhexyl group, 2,5-dimethylhexyl group, 2,5,5-trimethylpentyl group, 2,4-dimethylhexyl group, 2,2,4-trimethylpentyl Group, n-nonyl group, n-decyl group, 4-ethyloctyl group, 4-ethyl-4,5-methylhexyl group, n-undecyl group, n-dodecyl group, 1,3,5,7-tetraethyloctyl Group,
4-butyloctyl group, 6,6-diethyloctyl group, n-tridecyl group, 6-methyl-4-butyloctyl group, n-tetradecyl group, n-pentadecyl group, 3,5-dimethylheptyl group,
2,6-dimethylheptyl group, 2,4-dimethylheptyl group, 2,
2,5,5-tetramethylhexyl group, 1-cyclo-pentyl-2,2
-Dimethylpropyl group, 1-cyclo-hexyl-2,2-dimethylpropyl group and the like.

Examples of the alkoxyalkyl group include methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl, n-hexyloxyethyl, and the like. 4-methylpentoxyethyl group,
1,3-dimethylbutoxyethyl group, 2-ethylhexyloxyethyl group, n-octyloxyethyl group, 3,5,5-trimethylhexyloxyethyl group, 2-methyl-1-iso-propylpropoxyethyl group, 3- Methyl-1-iso-propylbutyloxyethyl group, 2-ethoxy-1-methylethyl group, 3-
Examples thereof include those having 2 to 15 carbon atoms such as a methoxybutyl group, a 3,3,3-trifluoropropoxyethyl group, and a 3,3,3-trichloropropoxyethyl group.

Examples of the alkoxyalkoxyalkyl group include methoxyethoxyethyl, ethoxyethoxyethyl, propoxyethoxyethyl, butoxyethoxyethyl, hexyloxyethoxyethyl, 1,2-dimethylpropoxyethoxyethyl, 3- Methyl-1-iso-
Butylbutoxyethoxyethyl group, 2-methoxy-1-methylethoxyethyl group, 2-butoxy-1-methylethoxyethyl group, 2- (2'-ethoxy-1'-methylethoxy) -1-methylethyl group, 3 A 3,3,3-trifluoropropoxyethoxyethyl group and a 3,3,3-trichloropropoxyethoxyethyl group.

Examples of the alkoxyalkoxyalkoxyalkyl group include a methoxyethoxyethoxyethyl group,
Examples thereof include an ethoxyethoxyethoxyethyl group, a butoxyethoxyethoxyethyl group, a 2,2,2-trifluoroethoxyethoxyethoxyethyl group, and a 2,2,2-trichloroethoxyethoxyethoxyethyl group.

Examples of the alkoxycarbonylalkyl group include methoxycarbonylmethyl, ethoxycarbonylmethyl, butoxycarbonylmethyl, methoxycarbonylethyl, ethoxycarbonylethyl, butoxycarbonylethyl, 2,2,3,3- Examples thereof include a tetrafluoropropoxycarbonylmethyl group and a 2,2,3,3-tetrachloropropoxycarbonylmethyl group.

Examples of the alkoxycarbonyloxyalkyl group include a methoxycarbonyloxyethyl group, an ethoxycarbonyloxyethyl group, a butoxycarbonyloxyethyl group, a 2,2,2-trifluoroethoxycarbonyloxyethyl group, a 2,2,2 -Trichloroethoxycarbonyloxyethyl group and the like.

Examples of the alkoxyalkoxycarbonyloxyalkyl group include a methoxyethoxycarbonyloxyethyl group, an ethoxyethoxycarbonyloxyethyl group, a butoxyethoxycarbonyloxyethyl group,
Examples thereof include a 2,2-trifluoroethoxyethoxycarbonyloxyethyl group and a 2,2,2-trichloroethoxyethoxycarbonyloxyethyl group.

Examples of the hydroxyalkyl group include a 2-hydroxyethyl group, a 4-hydroxyethyl group, a 2-hydroxy-3-methoxypropyl group, a 2-hydroxy-3-chloropropyl group, and a 2-hydroxy-3-ethoxy group. Propyl group, 3-butoxy-2-hydroxypropyl group, 2-hydroxy-3-phenoxypropyl group, 2-hydroxypropyl group, 2-hydroxybutyl group and the like.

Examples of the hydroxyalkoxyalkyl group include a hydroxyethoxyethyl group, 2- (2'-hydroxy-
1'-methylethoxy) -1-methylethyl group, 2- (3'-fluoro-2'-hydroxypropoxy) ethyl group, 2- (3'-chloro-2'-hydroxypropoxy) ethyl group and the like. Examples of the hydroxyalkoxyalkoxyalkyl group include a hydroxyethoxyethoxyethyl group, [2′-
(2'-hydroxy-1'-methylethoxy) -1'-methylethoxy] ethoxyethyl group, [2 '-(2'-fluoro-1'-hydroxyethoxy) -1'-methylethoxy] ethoxyethyl group,
[2 '-(2'-chloro-1'-hydroxyethoxy) -1'-methylethoxy] ethoxyethyl group and the like.

Examples of cyanoalkyl groups include 2-cyanoethyl, 4-cyanobutyl, 2-cyano-3-methoxypropyl, 2-cyano-3-chloropropyl, 2-cyano-3
-Ethoxypropyl, 3-butoxy-2-cyanopropyl, 2-cyano-3-phenoxypropyl, 2-cyanopropyl, 2-cyanobutyl and the like.

Examples of the acyloxyalkyl group include an acetoxyethyl group, a propionyloxyethyl group, a butyryloxyethyl group, a valeryloxyethyl group, a 1-ethylpentylcarbonyloxyethyl group, a 2,4,4-trimethylpentylcarbonyl Oxyethyl group, 3-fluorobutyryloxyethyl group, 3-chlorobutyryloxyethyl group and the like.Examples of acyloxyalkoxyalkyl group include acetoxyethoxyethyl group, propionyloxyethoxyethyl group, valeryloxyethoxy group. Ethyl group, 1-ethylpentylcarbonyloxyethoxyethyl group, 2,4,4-trimethylpentylcarbonyloxyethoxyethyl group, 2-fluoropropionyloxyethoxyethyl group, 2-chloropropionyloxyethoxyethyl group, and the like. Examples of the oxyalkoxyalkoxyalkyl group include an acetoxyethoxyethoxyethyl group, a propionyloxyethoxyethoxyethyl group, a valeryloxyethoxyethoxyethyl group, a 1-ethylpentylcarbonyloxyethoxyethoxyethyl group, and a 2,4,4-trimethylpentyl group. Examples thereof include a carbonyloxyethoxyethoxyethyl group, a 2-fluoropropionyloxyethoxyethoxyethyl group, and a 2-chloropropionyloxyethoxyethoxyethyl group.

Examples of the halogenated alkyl group include a chloromethyl group, a chloroethyl group, a 2,2,2-trifluoroethyl group, a trifluoromethyl group, a bromomethyl group and a methyl iodide group. Examples of the sulfonealkyl group include a sulfonemethyl group, a sulfoneethyl group, a sulfonepropyl group, and the like.

Examples of the alkylcarbonylaminoalkyl group include a methylcarbonylaminoethyl group, an ethylcarbonylaminoethyl group, a propylcarbonylaminoethyl group, a cyclohexylcarbonylaminoethyl group, a succiniminoethyl group and the like. Examples of the alkylsulfonaminoalkyl group include a methylsulfonaminoethyl group, an ethylsulfonaminoethyl group, a propylsulfonaminoethyl group, and the like.

Examples of the sulfonamidoalkyl group include:
Examples include a sulfonamidomethyl group, a sulfonamidoethyl group, and a sulfonamidopropyl group. Examples of the alkylaminoalkyl group include N-methylaminomethyl group, N, N-dimethylaminomethyl group, N, N-diethylaminomethyl group, N, N-dipropylaminomethyl group, N, N-dibutylaminomethyl Groups, and the like. Examples of the aminoalkyl group include an aminomethyl group, an aminoethyl group, an aminopropyl group and the like.

Examples of the alkylsulfonalkyl group include methylsulfonmethyl, ethylsulfonmethyl, butylsulfonmethyl, methylsulfonethyl, ethylsulfonethyl, butylsulfonethyl, 2,2,3,3- Examples thereof include a tetrafluoropropylsulfonemethyl group and a 2,2,3,3-tetrachloropropylsulfonemethyl group.

Examples of the substituted or unsubstituted alkoxy group are alkoxy groups having the same substituents as the above-mentioned alkyl groups, preferably methoxy, ethoxy, n-propoxy, iso-propoxy. Group, n-butoxy group, iso-butoxy group, sec-butoxy group, t-butoxy group,
Lower alkoxy groups such as n-pentoxy group, iso-pentoxy group, neo-pentoxy group and 2-methylbutoxy group are exemplified.

Examples of the substituted or unsubstituted aryl groups are aryl groups having the same substituents as the above-mentioned alkyl groups, preferably phenyl, nitrophenyl, cyanophenyl, hydroxyphenyl and the like. , A methylphenyl group, a trifluoromethylphenyl group, a naphthyl group, a nitronaphthyl group, a cyanonaphthyl group, a hydroxynaphthyl group, a methylnaphthyl group, a trifluoromethylnaphthyl group and the like.

Examples of the substituted or unsubstituted acyl groups include acyl groups having the same substituents as the above-mentioned alkyl groups, and preferably formyl, methylcarbonyl, ethylcarbonyl, n-propyl Carbonyl group, iso-propylcarbonyl group, n-butylcarbonyl group, iso-butylcarbonyl group, sec-butylcarbonyl group, t-butylcarbonyl group, n-pentylcarbonyl group,
Examples include an iso-pentylcarbonyl group, a neo-pentylcarbonyl group, a 2-methylbutylcarbonyl group, and a nitrobenzylcarbonyl group.

Examples of the substituted or unsubstituted alkyl carboxyl group include alkyl carboxyl groups having the same substituents as the above-mentioned alkyl groups, preferably methyl carboxyl group, ethyl carboxyl group, and n-carboxyl group.
Propyl carboxyl, iso-propyl carboxyl, n-butyl carboxyl, iso-butyl carboxyl, sec-butyl carboxyl, t-butyl carboxyl, n-pentyl carboxyl, iso-pentyl carboxyl, neo-pentyl carboxyl And a lower alkylcarboxyl group such as a 2-methylbutylcarboxyl group.

Examples of the substituted or unsubstituted aralkyl groups are aralkyl groups having the same substituents as the above-mentioned alkyl groups, preferably benzyl, nitrobenzyl, cyanobenzyl, hydroxybenzyl , Methylbenzyl, trifluoromethylbenzyl, naphthylmethyl, nitronaphthylmethyl, cyanonaphthylmethyl, hydroxynaphthylmethyl, methylnaphthylmethyl, trifluoromethylnaphthylmethyl and the like.

Examples of the substituted or unsubstituted alkylcarbonylamino group include an alkylcarbonylamino group having the same substituent as the above-mentioned alkyl group, preferably a methylcarbonylamino group, an ethylcarbonylamino group, n-propylcarbonylamino group, iso-propylcarbonylamino group, n-butylcarbonylamino group, iso-butylcarbonylamino group, sec-butylcarbonylamino group, t-butylcarbonylamino group, n-pentylcarbonylamino group, iso And lower alkylcarbonylamino groups such as -pentylcarbonylamino group, neo-pentylcarbonylamino group, 2-methylbutylcarbonylamino group, cyclohexylcarbonylamino group, and succinimino group.

Examples of the substituted or unsubstituted alkylsulfonamino group include an alkylsulfonamino group having the same substituent as the above-mentioned alkyl group, preferably a methylsulfonamino group, an ethylsulfonamino group, n-propyl sulfone amino group, iso-propyl sulfone amino group, n-butyl sulfone amino group, iso-butyl sulfone amino group, sec-butyl sulfone amino group, t-butyl sulfone amino group, n-pentyl sulfone amino group, is
and lower alkylsulfonamino groups such as o-pentylsulfonamino group, neo-pentylsulfonamino group, 2-methylbutylsulfonamino group, and cyclohexylsulfonamino group.

Examples of the substituted or unsubstituted alkylamino group include an alkylamino group having the same substituent as the above-mentioned alkyl group, preferably an N-methylamino group or an N, N-dimethylamino group. And lower alkylamino groups such as N, N-diethylamino group, N, N-dipropylamino group and N, N-dibutylamino group.

Examples of the substituted or unsubstituted alkylsulfone group include an alkylsulfone group having the same substituent as the above-mentioned alkyl group, preferably a methylsulfone group, an ethylsulfone group, or an n-propylsulfone group. Group, iso-propylsulfone group, n-butylsulfone group, is
o-butyl sulfone group, sec-butyl sulfone group, t-butyl sulfone group, n-pentyl sulfone group, iso-pentyl sulfone group, neo-pentyl sulfone group, 2-methylbutyl sulfone group, 2-hydroxyethyl sulfone group, And lower alkylsulfone groups such as a 2-cyanoethylsulfone group.

Examples of the substituted or unsubstituted alkenyl groups are alkenyl groups having the same substituents as the above-mentioned alkyl groups, and are preferably a propenyl group, a 1-butenyl group, an iso-butenyl group, -Pentenyl group, 2-pentenyl group, 2-methyl-1-butenyl group, 3-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2,2-dicyanovinyl group, 2-cyano-2- And lower alkenyl groups such as a methylcarboxylvinyl group and a 2-cyano-2-methylsulfonevinyl group.

Examples of the substituted or unsubstituted alkylthio groups are the alkylthio groups having the same substituents as the above-mentioned alkyl groups, preferably a methylthio group,
Ethylthio, n-propylthio, iso-propylthio, n-butylthio, iso-butylthio, sec-butylthio, t-butylthio, n-pentylthio, iso-pentylthio, neo-pentylthio, 2- And lower alkylthio groups such as methylbutylthio group and methylcarboxylethylthio group.

Examples of the substituted or unsubstituted alkylazomethine group include an alkylazomethine group having the same substituent as the above-mentioned alkyl group, preferably a methylazomethine group, an ethylazomethine group, an n-propylazomethine group. Group, iso-propylazomethine group, n-butylazomethine group, iso-butylazomethine group, sec-butylazomethine group, t-butylazomethine group, n-pentylazomethine group, iso-pentylazomethine group, neo-pentylazomethine group, And lower alkylazomethine groups such as a 2-methylbutylazomethine group and a hydroxyethylazomethine group.

Examples of the substituted or unsubstituted alkylaminosulfone group include an alkylaminosulfone group having the same substituent as the above-mentioned alkyl group, and preferably an N-methylaminosulfone group or an N-ethyl group. Aminosulfone group, N- (n-propyl) aminosulfone group, N- (iso-
Propyl) aminosulfone group, N- (n-butyl) aminosulfone group, N- (iso-butyl) aminosulfone group, N- (sec
-Butyl) aminosulfone group, N- (t-butyl) aminosulfone group, N- (n-pentyl) aminosulfone group, N- (iso
-Pentyl) aminosulfone group, N- (neo-pentyl) aminosulfone group, N- (2-methylbutyl) aminosulfone group, N- (2-hydroxyethyl) aminosulfone group, N- (2
-Cyanoethyl) lower alkylaminosulfone group such as aminosulfone group.

Examples of the case where R ₁ and R ₄ or R ₂ and R ₆ form a ring via a linking group include —CH ₂ CH ₂ — and —CH ₂ CH ₂ CH ₂ —
, -CH ₂ CH (Cl)-, -CH ₂ C (= O) CH _2- , -CH ₂ C (= O)-, -CH ₂ C
H ₂ C (= O) —, —CH ₂ CH (F) —, or —CH ₂ CH (OH) —.

Examples of the case where R ₁ and R ₂ form a ring via a linking group include -CH ₂ CH ₂ OCH ₂ CH _2- , -CH ₂ CH ₂ NHCH ₂ CH ₂ -,-
CH ₂ CH ₂ N (CH ₃ ) CH ₂ CH ₂ --CH ₂ C (= O) OC (= O) CH _2- , -CH ₂ C (= O)
NHC (= O) CH _2- , -CH ₂ C (= O) N (CH ₃ ) C (= O) CH _2- , or -CH ₂ C
H ₂ CH ₂ CH ₂ CH _2- and the like.

The azo compound of the present invention represented by the formula (1) is produced by a known method as follows. That is, the amine component represented by the formula (3) [formula 5] is diazotized, added to a solution of the coupling component represented by the formula (4) [formula 5], subjected to a coupling reaction, and subjected to a coupling reaction represented by the formula (1). Is obtained.

[0054]

Embedded image [In the above formula, R _{1 to} R ₇ , X and Y have the same meanings as in formula (1). ]

In the present invention, the method for producing the metal complex of the azo compound is a known method, for example, Furukawa;
ytica Chimica Acta 140 (1982) 281-289. As the metal forming the metal complex of the azo compound, for example, metals such as nickel, cobalt, iron, ruthenium, rhodium, palladium, copper, osmium, iridium, platinum, zinc, magnesium and manganese are preferable, and particularly nickel, cobalt,
Copper, palladium, iron, zinc and manganese are preferred. These are used in the form of acetates, halides, BF4 ^- salts and the like at the time of production, and Ni2 ⁺ , Co2 ⁺ , Co3 ⁺ , Cu2 ⁺ , Pd2 ⁺ ,
It is obtained as a complex coordinated to an azo compound as Fe ²⁺ , Fe ³⁺ , Zn ²⁺ , Mn ²⁺ or the like. The metal complex of the azo compound may be used alone or as a mixture of a plurality of compounds. Further, a quencher such as a dithiol complex may be mixed.

In the present invention, a recording layer containing the above-described dye is provided directly on the substrate or via another inorganic or organic layer (undercoat layer). The method for providing the recording layer includes, for example, a spin coating method, a dipping method, a spraying method, and a vapor deposition method, and the spin coating method is preferable.

The coating solvent for forming a film by spin coating is not particularly limited as long as it does not damage the substrate. Preferred solvents include, for example, ethyl alcohol, propyl alcohol, butyl alcohol,
Examples include alcohol solvents such as furfuryl alcohol, ethylene glycol monomethyl ether, and tetrafluoropropanol.

When forming the recording layer, a binder may be used together if necessary. Preferred binders include nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polyvinyl butyral, polycarbonate, polyolefin and the like. Further, other dyes can be added for improving recording characteristics and the like. Although the thickness of the recording layer affects the degree of modulation and the reflectance, in the present invention, the thickness is 40 nm to 300 nm, preferably 60 nm to 20 nm.
0 nm.

When the recording layer is formed on the substrate, a layer made of an inorganic substance or a polymer may be provided on the substrate in order to improve the solvent resistance, the reflectance, the recording sensitivity and the like of the substrate.

In the present invention, a reflective layer is provided on the recording layer. As the reflective layer, metals such as gold, silver, aluminum, copper and platinum and alloys containing these metals are used. In terms of reflectance and durability, gold, aluminum, silver, or an alloy containing these metals as a main component is preferable. The thickness of the reflective layer is usually 40 nm to 300 nm, preferably 60 nm to 200 nm. The method for forming the reflective layer is as follows:
For example, a vacuum deposition, a sputtering method, an ion plating method and the like can be mentioned.

In the present invention, a light interference layer may be provided between the recording layer containing the dye and the reflective layer in order to improve the characteristics such as the reflectance and the degree of modulation. Examples of a material for forming the light interference layer include an inorganic dielectric, a polymer, and a dye.

In the present invention, since the numerical aperture of the objective lens is large, the thickness of the substrate is set to 0.5 to reduce aberration.
It is preferably about 0.8 mm. At this time, in order to improve the strength and mechanical properties of the medium, two sheets may be attached to each other using an adhesive. In bonding, the bonding can be performed without forming a protective layer on the reflective layer, or after forming the protective layer. UV-curable acrylic resin, UV-curable epoxy resin,
A silicone hard coat resin or the like is used. In addition, as an adhesive for bonding, an ultraviolet curable acrylic resin, an ultraviolet curable epoxy resin, a hot melt adhesive, or the like is used.

The optical recording medium of the present invention thus obtained can perform recording and reproduction at a much higher density than the beam diameter by focusing the laser beam on the recording layer. As a signal at the time of recording, for example, a modulation signal used for a CD, a DVD, or the like is preferable for achieving the effects of the present invention.

[0064]

EXAMPLES The present invention will be described below in more detail with reference to examples, but embodiments of the present invention are not limited thereto. Example 1 Spiral groove having a thickness of 0.6 mm and a diameter of 120 mm (depth 100 nm, width 0.28 μm, pitch 0.
While rotating the resin substrate on the grooved surface of an injection-molded polycarbonate substrate having a thickness of 80 μm), the azo dye Ni complex represented by the following formula (5)
A 5% by weight solution of 2,2,3,3-tetrafluoro-1-propanol was added dropwise to form a recording layer consisting essentially of a dye on the substrate. The thickness of the recording layer was 100 nm.

[0065]

Embedded image

A 80 nm thick reflective layer was formed on this recording layer.
After forming a gold thin film by sputtering, an ultraviolet curing adhesive was applied on the reflective layer. The same 0.6 mm substrate as described above was overlaid on this adhesive, rotated at a high speed to remove excess adhesive, and then irradiated with ultraviolet rays to produce an optical recording medium bonded thereto.

This optical recording medium is put on a turntable,
While rotating at a linear speed of 2.8 m / s, an optical disk evaluation device (DDU-1000) manufactured by Pulstec Industrial equipped with an optical head composed of a semiconductor laser having an oscillation wavelength of 640 nm and an objective lens having an NA of 0.6, and manufactured by KENWOOD Using an EFM encoder, while controlling the laser beam to focus on the recording layer on the groove through the substrate, the minimum pit length is 0.4 μm while changing the recording laser power.
After recording the EFM modulated signal, the recorded signal was read using the same apparatus at a laser output of 0.5 mW. Note that an equalization process was performed when reading. When the recording power is 8.0 mW laser output, the error rate is the smallest (optimum recording power), the byte error rate is 5 × 10 ^-4 , and the jitter at that time is both the rise and fall of the pit and the channel bit. Clock
7.0%. The reflectance of the unrecorded area is 52%, the modulation degree of the shortest pit (I3 / I11: the ratio of the shortest pit amplitude to the longest pit amplitude) is 26%, and the crosstalk is 61%.
Extremely good recording and reproduction were achieved. Almost no distortion was observed in the reproduced waveform. In this case, Wg is 0.
26r and P were 0.75r.

Example 2 The medium prepared in Example 1 was replaced with
A semiconductor laser with an oscillation wavelength of 633 nm and NA of 0.
Evaluation was performed in the same manner as in Example 1 except that an optical disk evaluation apparatus (DDU-1000) manufactured by Pulstec Industrial equipped with an optical head having 63 objective lenses was used. Recording power is 8.
When the laser output is 2 mW, the error rate is the smallest (optimum recording power), the byte error rate is 3 × 10 ^-4 ,
The jitter at that time was 7.3% of the channel bit clock at both the rising and falling of the pit. The reflectance of the unrecorded area is 50%, and the modulation degree of the shortest pit (I3 / I11:
Ratio of shortest pit amplitude to longest pit amplitude)
30% and crosstalk were 58%, and extremely good recording and reproduction were possible. Almost no distortion was observed in the reproduced waveform. In this case, Wg is 0.28r and P is 0.80r.
Met.

(Examples 3 to 6 and Comparative Examples 1 to 3) A medium was prepared and evaluated in the same manner as in Example 1 except that a groove-shaped substrate shown in Table 1 was used.
The results are summarized in [Table 2]. As is apparent from Table 2, extremely good recording and reproduction were achieved in the example of the present invention, but in the comparative example, the crosstalk was large, the modulation degree of the shortest pit was small, and the error rate and the jitter were small. And good recording and reproduction could not be performed.

[0070]

[Table 1]

[0071]

[Table 2]

(Examples 7 to 10) As a dye used in the recording layer, an azo compound represented by the following formulas (6) to (8) or a metal complex shown in [Table 3] of the azo compound was used. Used, track pitch 0.8 μm, groove width 0.
A medium was prepared and evaluated in the same manner as in Example 1 except that a substrate having a thickness of 32 μm and a depth of 100 nm was used. The results are summarized in [Table 3]. In this case, Wg is 0.30r and P is 0.75r.
Met.

[0073]

Embedded image

[0074]

[Table 3]

[0075]

As is clear from the examples and comparative examples of the present invention, in the present invention, in an optical recording medium having a recording layer containing at least a dye and a reflective layer on a substrate, the recording layer By including a specific dye and defining the track pitch and groove width with respect to the recording beam diameter represented by λ / NA (λ is the recording wavelength, NA is the numerical aperture of the objective lens), crosstalk is possible. Can be as small as possible,
High-density recording is possible.

[Brief description of the drawings]

FIG. 1 is a structural sectional view showing an example of a layer configuration of an optical recording medium of the present invention.

FIG. 2 is a structural sectional view showing an example of a layer configuration of the optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Reflective layer 4 Protective layer 1 'Substrate 2' Recording layer 3 'Reflective layer 4' Adhesive layer 5 'Substrate

Claims (3)

[Claims] 1. A recording layer containing a dye that absorbs laser light, directly or through another layer, on a transparent substrate having a groove, and directly or through another layer on the recording layer. In an optical recording medium having a metal reflective layer, the diameter of the recording beam represented by λ / NA is r [where λ is the recording wavelength (μm), NA is the numerical aperture of the objective lens], and the groove of the substrate is When the pitch (track pitch) is P (μm) and the width of the groove is Wg (μm), Wg and P satisfy the following formula: 0.24r ≦ Wg ≦ 0.35r 0.68r ≦ P ≦ 0.83r A high density optical recording medium characterized in that the dye contained in the recording layer is an azo compound represented by the following formula (1) or a metal complex thereof. Embedded image [Wherein, R ₁ and R ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfone group, a sulfonamide group, an amino group, a substituted or unsubstituted aryl group, a substituted or unsubstituted Acyl group, substituted or unsubstituted alkylcarboxyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted alkylcarbonylamino group, substituted or unsubstituted alkylsulfonamino group, substituted or unsubstituted alkylamino group, substituted Or an unsubstituted alkylsulfone group,
Represents a substituted or unsubstituted alkenyl group (here, when forming a metal complex, one of R ₃ and R ₅ is a hydroxy group, a carboxyl group, an amino group, a substituted or unsubstituted alkyl carboxyl group, Or an unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonamino group, a substituted or unsubstituted alkylamino group, and the other is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfonamide group, an amino group A substituted or unsubstituted aryl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted alkylcarboxyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkyl Sulfonamino group, substituted or unsubstituted alkylamino group, Is an unsubstituted alkylsulfone group,
Represents a substituted or unsubstituted alkenyl group. ), R ₁ and R
₄ , R ₂ and R ₆ and R ₁ and R ₂ may form a ring via a linking group, and R ₇ is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, a sulfone group, a sulfonamide group, an amino group. Group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryl group, substituted or unsubstituted acyl group, substituted or unsubstituted alkylcarboxyl group, substituted or unsubstituted aralkyl group A substituted or unsubstituted alkylcarbonylamino group, a substituted or unsubstituted alkylsulfonamino group, a substituted or unsubstituted alkylamino group, a substituted or unsubstituted alkylsulfone group, a substituted or unsubstituted alkenyl group, a cyano group, Nitro, mercapto, thiocyano, chlorosulfone, substituted or unsubstituted alkylthio, substituted or unsubstituted Alkyl azomethine group, a substituted or unsubstituted alkyl amino sulfone group, X
Is a sulfur atom or N-R ₈ (wherein, R ₈ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group,
Represents a substituted or unsubstituted alkenyl group. ), Y represents a nitrogen atom or C—R ₉ (where R ₉ has the same meaning as R ₇ ). However, when X is a sulfur atom, Y is a nitrogen atom, and when X is N—R ₈ , Y is C—R ₉ . ] 2. The high-density optical recording medium according to claim 1, wherein the dye contained in the recording layer is a metal complex of an azo compound represented by the following formula (2). Embedded image [Wherein R ₁ , R ₂ , R ₄ , R ₅ and R ₆ have the same meaning as in formula (1), R ₈ represents a hydroxy group or a carboxyl group, and R ₉ represents a hydrogen atom or a halogen atom. Represent. ] 3. λ is 0.630 to 0.655 μm, NA
Is 0.60 ± 0.05.
Or a high-density optical recording medium according to 2.