JPH10337959A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical recording medium excellent in long term reliability by employing an organic coloring matter thin film principally comprising a cyanine based coloring matter shown by a specific formula applicable to short wavelength laser light. SOLUTION: The optical recording medium comprises a recording layer 2 of an organic coloring matter thin film applicable to short wavelength laser light principally comprising a cyanine based coloring matter shown by a formula [where, X represents an ion of iodide, bromide, perchloric acid, fluoroboric acid, tetrafluorophosphate, or tetrafluoroantimonate, one of R1 , R2 represents a substituent of 2-18C having unsaturated linkage and the other represents an alkyl group or an aryl group, Y1 , Y2 represents a hydrogen or halogen atom, an alkyl, aryl, alkoxy, nitro, hydroxyl, carboxyl, -OCF2 , -R3 OH, -R3 COOR4 , -CH=CHN, -COOR4 , -R3 COOH, or -COR3 group (R3 is an alkylene group of 1-9C and R4 is an alkyl group of 1-9C), n, m is an integer of 1-4, and (Y1 )n , (Y2 )m exhibits asymmetric structure in a cyanine based coloring matter molecule].

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 for performing high-density recording and reproduction using short-wavelength laser light, and more particularly, to using an organic dye thin film whose light reflectance changes by short-wavelength laser light to reduce spot light. And a write-once optical recording medium conforming to DVD, which is excellent in sensitivity, reliability, etc., capable of recording and reproducing information at high density.

[0002]

2. Description of the Related Art Recordable optical information recording media are widely used. The optical recording medium has a feature that the recording (recording) or reading (reproducing) head is not in contact, so that the recording medium does not deteriorate due to wear. By making the spot diameter of the light beam smaller, large-capacity information can be obtained. It is attracting attention as a carrier and is being developed.

For example, a laser beam is focused on a recording layer, converted into thermal energy, and the properties of the recording film are changed by melting, decomposing, removing, or the like to form a deformed layer pit. The reproduction can be performed by the change in the amount of reflected light. As a recording layer, a chalcogenide-type metal film typified by tellurium was initially put to practical use, but it was harmful, the film formation was a dry method, the need for higher density and the need for higher manufacturing costs Due to the need to reduce the cost, proposals and reports on media using a recording layer containing an organic dye as a main component instead of tellurium have increased. The reason is that the reflectance is lower than metal,
(1) The recording layer can be formed into a thin film by a wet method typified by a spin coating method; (2) it is excellent in oxidation resistance and is not corroded; Local heating can be performed without exerting the influence of heat on the peripheral portion, and (4) many excellent properties such as high sensitivity can be achieved.

Conventionally, a so-called air sandwich structure in which an air layer is provided on a recording layer made of a dye film, which has been widely used, and an optical information recording medium capable of obtaining a reproduction signal conforming to the CD standard are known. Proposed. These are described in JP-B-3-759343, JP-A-2-87341, JP-A-5-67352 and the like, and Nikkei Electronics No. 469, p107, January 23, 1989.

[0005] As an optical recording disk conforming to the CD standard, a light absorbing layer made of an organic dye is formed on a translucent resin substrate, and a high reflectance of 65% or more can be obtained with the organic dye film alone. It is known that a light reflection layer typified by Au is formed directly or via a hard layer, and a resin protective layer is formed thereon. When this disc is irradiated with laser light, the organic dye layer absorbs the light and melts or decomposes, and at the same time, softens the substrate, and the dye and the substrate mix at the interface to form recording pits whose interface is finally deformed. Is done. In the deformed layer pits formed in this manner, the light reflectance changes due to the optical phase difference as in the case of the CD, so that reading can be performed.

The organic dyes used in these are squarylium dyes (JP-A-56-46221, JP-A-63-621).
-218398, JP-A-1-178494, JP-A-5-139047, JP-A-7-449
04), naphthoquinone dyes (JP-A-61-2)
90092, JP-A-62-432, JP-A-63-168201, JP-A-1-13947), azo dyes (JP-A-7-16069,
JP-A-7-251567, JP-A-8-99467
), Phthalocyanine dyes (JP-A-57-820)
No. 94, JP-A-57-82095 and JP-A-7-82095.
JP-156550, JP-A-7-16068,
JP-A-7-52544) and the following general formula (II
Cyanine dyes represented by the formula (I) (JP-A-59-2469);
No. 2, JP-A-6-199045, JP-A-7-1990
262611, JP-A-6-338059,
JP-A-6-320869, JP-A-2-87341
Gazette, Japanese Patent Application Laid-Open No. 62-201288,
No. 4981).

[0007]

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[In the general formula (III), S ₁ and S ₂ each represent an alkyl group, an aryl group or an alkoxyl group, and W ₁ and W ₂ represent a halogen atom, a hydrogen atom, an alkyl group, an alkoxyl group, an aryl group, Z represents an alkoxysulfonyl group, a sulfonylalkyl group, or a cyano group;
₁ and Z ₂ each represent a sulfur atom, an oxygen atom, a selenium atom, ethylene, or the like. Among the above-mentioned dyes, cyanine dyes represented by the general formula (III) are mainly used in terms of sensitivity, S / N ratio, C / N ratio, thermal properties, ease of thinning, and the like. Generally, a dye having an absorption and a reflectance around 780 nm to 830 nm from the semiconductor laser wavelength. In order to conform to the CD, the number of methylene chains at the center of the molecular structure is 2 (q is 2 in the general formula (III)).
Is common. However, cyanine dyes having 2 methylene chains cannot cope with short-wavelength lasers.
Further, the cyanine dyes represented by the general formula (III) are said to have problems in reproduction deterioration, long-term stability of the film, jitter components and the like. The above-mentioned causes are that heat accumulation occurs in the recording layer due to exposure with the reading light for a long time, and the dye itself deteriorates and fades. At the boundary surface, melting or thermal deformation occurs gradually,
Further, the same heat accumulation causes the contours of the deformed layer pits to be deformed and overlapped. Thus, C / N
The ratio decreases and the jitter component increases. Deterioration of the cyanine dye due to natural light and oxygen is also a cause of the change in the absorptivity of the dye, and association and aggregation of the dyes due to oxygen, moisture and the like are also considered to be the causes of the change in the absorptivity and the generation of noise. Various proposals have hitherto been made to solve this problem.
For example, JP-A-62-201288, JP-A-62-22012
2012289, JP-A-57-66541,
JP-A-59-124894, JP-A-59-203
247, JP-A-62-133173, JP-A-63-198096, and JP-A-59-21339.
JP-A-57-11090, JP-A-60-11090
44389, JP-A-60-71296, JP-A-63-1594, JP-A-57-11090, JP-A-5-38879, JP-A-7-262
No. 611, Japanese Patent Application Laid-Open No. 7-4981, etc. disclose the disclosure. However, it has not yet been fully resolved.

On the other hand, an optical disk having a high recording density conforming to the DVD has been developed as a high-density optical memory.
Since the spot diameter is expressed by wavelength (λ) / numerical aperture (N) of the objective lens, the wavelength of the semiconductor laser is shorter than that of the current CD and is set to about 600 to 680 nm, and further, an SHG element or the like is used. There is a method of shortening the wavelength of light, narrowing down to the laser diffraction limit with an objective lens, and reducing the beam spot diameter to increase the recording density, and a recording medium corresponding to this method is required.

Further, cyanine dyes for short wavelengths have been proposed as improvements of CD-compatible cyanine dyes represented by the general formula (III) (JP-A-6-199045 and JP-A-7-186530). JP-A-8-306
No. 074, JP-A-5-38879, JP-A-6-38879
-40162 publication etc.).

[0011]

However, sensitivity or film stability (reliability) corresponding to the target wavelength cannot be obtained, and the density is included in the reproduced signal due to thermal interference between adjacent pits when the density is increased. Many problems, such as an increased jitter component, have not been solved. The present invention has been made in view of the above points, and its object is to provide high sensitivity to short-wavelength semiconductor laser light having a wavelength of 500 to 700 nm, as well as chemical, photochemical,
By finding a recording film mainly composed of a cyanine-based organic dye with good physical and thermal stability, a DVD-compliant optical recording medium with high recording density, low jitter component and excellent long-term reliability has been developed. To provide.

[0012]

Means for Solving the Problems The present inventor has conducted intensive studies on various cyanine dyes in order to solve the above-mentioned problems. As a result, the number of methylene groups connecting two indole nuclei of the cyanine dye is one. Found that the substituent attached to the nitrogen atom of the indole nucleus has an unsaturated group, and that the molecular symmetry of the substituent or residue attached to the two benzene rings of the indole nucleus affects the above properties. The present invention has been accomplished based on this finding.

According to the first aspect of the present invention, there is provided a recording layer, a metal reflection layer, and a light-transmitting substrate which supports the recording layer and the metal reflection layer on a main surface having a groove. In the optical recording medium formed by using the recording medium, the recording layer is achieved by using an organic dye thin film containing at least one cyanine dye represented by the following general formula (I) as a main component.

[0014]

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[In the general formula (I), X ^- represents an iodide ion, a bromide ion, a perchlorate ion, a fluoroborate ion, a tetrafluorophosphate ion, a tetrafluoroantimonate ion, a methyl sulfate ion, or a methyl ion. It represents a benzene sulfonate ion, a substituent having 3 to 18 carbon atoms where one of R _1, R ₂ has an unsaturated bond and the other represents an alkyl group, an aryl group or an alkoxyl group,, Y _1, Y ₂ is a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group, a halogen atom, a nitro group, a hydroxyl group, a carboxyl group, a —OCF ₃ group, —R ₃ OH
Group, -R ₃ COOR ₄ group, -CH = CHCN group, -COO
R ₄ group, —R ₃ COOH group, —COR ₃ group (wherein R ₃ is an alkylene group having 1 to 9 carbon atoms, and R ₄ is a 1 to 9 carbon atoms)
9) or a residue forming a naphthalene ring which may be substituted by condensing with a benzene ring, n and m are integers of 1 to 4, (Y ₁ ) _n and (Y ₂ ) _m are cyanine It shows asymmetry within the dye molecule. In the first invention, the cyanine dye represented by the general formula (I) is a composite system of two or more kinds, and in the first and second inventions, the recording layer contains 1% or more of oxygen quencher. That is, in the first to third inventions, the metal reflection layer has a high melting point, and has a light reflectance of 5 to a short wavelength laser beam.
5% or more of Al, Au, Ag, Cu, Ni, Ti or a thin film of a metal selected from the group of chalcogenide-based metals;
In the first to fourth inventions, a recording layer and a metal reflection layer are sequentially laminated on a substrate, and a protective layer is further laminated, and the recording layer is formed on a substrate formed with grooves in the first to fourth inventions. And a metal reflective layer are sequentially laminated, and a one-sided substrate on which a protective layer is further laminated and a non-groove substrate are bonded with an adhesive, and in the first to fourth inventions, the recording layer and the metal are formed on the substrate. A two-sided type in which a reflective layer is sequentially laminated and a protective layer is further laminated, and a two-sided type is bonded to each other with a protective layer interposed therebetween. It is effective to use a double-sided type in which a groove is formed and a recording layer and a metal reflection layer are sequentially laminated on the main surface, and a protective layer is further laminated.

As shown in the cyanine dye of the general formula (I), the methylene group has 1 chain, and the substituent R ₁ having 3 to 18 carbon atoms and having an unsaturated bond at the nitrogen atom of the indole nucleus.
When R ₂ is bonded and the substituents or residues bonded to the two benzene rings of the indole nucleus show mutual asymmetry, the cyanine dye is highly sensitive to short wavelengths (500 to 700 nm), And good photochemical, physical and thermal stability.

The oxygen quencher prevents deterioration of the cyanine dye due to ultraviolet light, laser light, and the like, and improves the light stability of the cyanine dye. Metal reflective layer is Al, Au, Ag, Cu, N
A thin film of a metal selected from the group consisting of i, Ti and chalcogenide-based metals has a large light reflectance to laser light. The sticking type is manufactured using a one-sided optical recording medium.

The double-sided type is easily manufactured using a substrate having grooves formed on two main surfaces.

[0019]

FIG. 1 is a schematic sectional view showing a single-sided optical recording medium according to an embodiment of the present invention. FIG. 2 is a schematic sectional view showing a one-sided optical recording medium according to another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a sticking type optical recording medium according to another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a double-sided optical recording medium according to still another embodiment of the present invention. The substrate 1 has, for example, a disc shape, and tracking pre-pits or pre-grooves are formed concentrically or spirally on one principal surface (one-sided and sticking type) or two principal surfaces (two-sided surface) of the substrate. Is done. The substrate having such pre-pits or pre-grooves is made of an injection-molded resin from the viewpoint of productivity and the like, and is preferably substantially used for recording light and reproduction light (semiconductor laser light of about 500 to 700 nm, particularly 600 to 680 nm). A transparent resin (having a laser beam transmittance of 85% or more) is used. 1 to 4 is about 1.0 to 1.5 mm. In the case of the sticking type, the one having a thickness of about 0.5 to 0.65 mm is bonded. In the double-sided mold, pre-pits or pre-grooves are simultaneously formed on two main surfaces. All have a diameter of about 54 to 120 mm, and the resin constituting the substrate is not particularly limited. However, thermoplastic resin such as polycarbonate resin, polyacryl resin, polyester resin, amorphous olefin resin, TPX, arton resin, etc. Resin is used. The track pitch is 0.7 to 1.6 μm. The depth of the groove is
It is used for tracking control and information retention depending on the phase of the laser light.
It is about 0 to 200 nm. If the groove is too shallow, the deformation rate of the groove bottom surface and the influence on the metal reflection layer are likely to be large, and the distortion of the reproduced signal is likely to be induced, which causes the jitter to increase and the modulation degree to decrease. On the other hand, if the groove is too deep, the amount of deformation of the groove bottom surface of the recording mark portion becomes unstable, and the jitter increases. Therefore, the wavelength dependence of the reproduction signal and the tracking signal increases. Therefore, the depth of the groove is important depending on the wavelength of the semiconductor laser beam at the time of high-density recording, and it is necessary to optimize the depth, shape, and the like according to the characteristics and film forming properties of the recording film.

For the recording layer 2, a cyanine dye represented by the general formula (I) is used. Each of the cyanine dyes of the present invention has an absorption / reflection wavelength at 500 to 700 nm when formed into a thin film, and has sufficient sensitivity and reflectance to a target laser wavelength (600 to 680 nm). Particularly, among the substituents, R
₁ , R ₂ is allyl, vinyl, arylidene, aryleoxy,
Each group such as crotonoyl, styryl, vinylidene, vinylene, methylidine, acryloxy, methallyloxy, isopropenyl, ethynyl, and butenyl can be exemplified, and the compatibility between the film and the substrate surface is good. The number of carbon atoms is 3 to 18, preferably 3 to 9 position. If the number of carbon atoms is too large, molecular association tends to occur, which may cause noise.

In the present invention, by introducing the substituents of Y ₁ and Y ₂ asymmetrically with the introduction of R ₁ and R ₂ , the aggregation and association phenomena of the dye can be suppressed. With the above effects, a recording layer having excellent film formation stability and reliability can be obtained. The cyanine dye represented by the general formula (I) can be synthesized by a known synthesis method (for example, USP 2,734,900, USP 2,112,139, USP
No. 2,887,479, USP 3,410,848, USP 2,112,
140, etc.). A specific example is shown below.

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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The cyanine dye of the present invention may be used alone, but by combining two or more kinds thereof, the spectral properties (absorption of laser light, light reflectance, etc.) can be adjusted and the thin film in an amorphous state can be formed. Stability is improved, sensitivity is increased, jitter components and noise are reduced, and long-term storage is improved. The recording layer 2 may contain an oxygen quencher (light stabilizer) in an amount of 1% or more together with the cyanine dye. Preferably it is about 1 to 20% (more preferably 3 to 20%). This quencher captures radicals generated by the deterioration of the cyanine dye due to ultraviolet light, laser light, or the like, and stops the chain reaction. Improves light stability and particularly prevents fading due to reproduction light. Thus, the recording layer of the present invention can suppress the flow of the film due to light generation, as well as the long-term storage properties, and can suppress the generation of noise and the rise of jitter. The following are specific examples of the oxygen quencher used together with the dye. [Metal complex type] Q1: bis (4-tetra-butyl-1,2-dithiophenolate) M-tetra-n-butylammonium M is Cu, Co, Ni, Fe, etc. (BBT manufactured by Sumitomo Seika Co., Ltd.) Series
Q2: bis [4- (diethylamino) -α, β-stilbene dithiolate] nickel (NKX-114 manufactured by Japan Photographic Dye Laboratories, Inc.) Q3: bis [3-methoxy-4- (2-methoxyethoxy) ) -2'-Chloro-α, β-stilbene dithiolate]
Nickel (NKX-1199 manufactured by Japan Photographic Dye Laboratories) Q4: 1.2-benzenedithiol-nickel complex (PA-1006 manufactured by Mitsui Toatsu Chemicals, Inc.) [Amine / ammonium salt system] Q5: Bisiminium salt (Japan Q6: N, N, N ', N "-tetrakis (p-dibutylaminophenyl) p-phenylenediamine (NIR-AM1 manufactured by Teikoku Chemical Co., Ltd.) Q7: 4-Nitroso -4 '-(dimethylamino) diphenylamine (NKX-1549, manufactured by Japan Photosensitive Dye Laboratories Co., Ltd.) Although not particularly limited, it may be added alone or in combination.

The above-mentioned cyanine dye is an oxygen quencher
With a coating solvent that does not attack the substrate, such as methyl cellosolve, ethyl cellosolve, methanol, ethanol, isopropanol, diacetone alcohol, dimethylformamide, cyclohexanone, acetylacetone, tetrafluoropropanol, dichloroethane, dioxane, etc. A film is formed on a substrate made of the above resin and having grooves formed thereon by a common means such as.

The thickness of the recording layer 2 is about 50 to 500 nm, preferably about 50 to 300 nm. If it is less than 50 nm, recording sensitivity and light reflectance are insufficient, and ideal recording cannot be performed. On the other hand, if the value exceeds 300 nm, a tracking signal cannot be obtained, and pits may overlap. For this reason, jitter increases, waveform distortion of a reproduced signal is apt to occur, and causes an increase in crosstalk. It is important that this film thickness is adjusted in consideration of film forming conditions, dye concentration and groove shape.

The metal reflective layer 3 has a higher melting point than the recording layer 2 and an Al, Au, Ag, Cu, Ni, Ti or chalcogenide based material having a light reflectance of 55% or more, preferably 65% or more with respect to the laser beam. It is a metal thin film selected from metals and has a thickness of 30 to 150 nm, preferably about 50 to 100 nm. For this thin film forming method, sputtering, vacuum deposition, ion plating, or the like is used.

The protective layer 4 is generally formed by applying an ultraviolet curable resin by a spin coating method, a spray coating method, a gravure coating method or the like, and then irradiating ultraviolet rays to cure the coating film. , Acrylic resin, silicone resin and the like are used. It may be in the form of a sheet. The double-sided protective layer 4 may be the above-described protective layer, or an inorganic film such as SiOX may be formed by sputtering, vapor deposition, or the like. Alternatively, a polymer film obtained by polymerizing a resin such as parylene, polyamide, or polyimide by vapor deposition, plasma, or the like may be used. This film thickness is about 0.5 to 50 μm.

The sticking type optical recording medium is a high-density optical recording medium that can be recorded / reproduced on one side and on both sides by laminating with an adhesive such as hot melt, ultraviolet ray / visible curing type or adhesive tape. This optical recording medium has a structure in which a recording layer mainly containing a cyanine dye having a specific structure is provided on a substrate, and has a sufficient sensitivity and light reflectance corresponding to a short wavelength laser of 500 to 700 nm. In addition, high-density recording with low jitter and excellent long-term reliability without reproduction deterioration is achieved.

[0038]

【Example】

Example 1 As a substrate used, a polycarbonate substrate having a thickness of 6 mm and a track pitch of a groove of 0.75 μm was used. A cyanine-based dye represented by the chemical formula (I-2) as a laser-absorbing dye, and a mixture of the above-mentioned Q3 and Q6 at a weight ratio of 2: 1 (7% by weight based on the laser-absorbing dye) as an oxygen quencher were ethyl cellosolve. / Ethanol / diacetone alcohol mixed solvent (mixed at a weight ratio of 5: 3: 2)
In the solution, the concentration was adjusted to 6% by weight and dissolved sufficiently using ultrasonic waves. After filtration with a filter, the substrate was coated on the substrate by spin coating to obtain a uniform recording layer 2 having a thickness of 60 nm. Subsequently, Al was formed to a thickness of 70 nm by a sputtering method to obtain a metal reflection layer 3. Furthermore, a protective layer 4 was obtained by applying and curing a multifunctional epoxy acrylate-based ultraviolet curable paint by a spin coat method. The thickness is about 6 μm.

In order to obtain an adhesive optical recording medium, two single-sided optical recording media are heated and pressed at a low temperature using a hot-melt type adhesive, and the protective layers are adhered to each other to form a desired optical recording medium. Obtained. Example 2 A cyanine-based dye represented by the chemical formula (I-2) and the chemical formula (I-
An optical recording medium was prepared in the same manner as in Example 1 except that the cyanine dye shown in 13) was compounded at a weight ratio of 2: 1. Example 3 A cyanine-based dye represented by the chemical formula (I-2) and the chemical formula (I-
An optical recording medium was prepared in the same manner as in Example 1 except that the cyanine dye shown in 9) was compounded at a weight ratio of 2: 1 and Q1 and Q7 were mixed at a weight ratio of 2: 1 as an oxygen quencher. Prepared. Example 4 A cyanine-based dye represented by the chemical formula (I-13)
An optical recording medium was prepared in the same manner as in Example 1, except that the cyanine dye shown in -24) was compounded at a weight ratio of 1: 1. Example 5 A dye system in which the dye represented by the chemical formula (-28) and the dye represented by the chemical formula (-35) were combined at a weight ratio of 1: 1 and Q1 and Q6 were mixed at a weight ratio of 1: 1 as an oxygen quencher. The resulting solution (10% by weight based on the laser absorption dye) was sufficiently dissolved in tetrafluoropropanol to a concentration of 2% by weight using ultrasonic waves. After the solution was filtered with a filter, a recording layer 2 having a thickness of 80 nm was formed on the substrate by spin coating, and then an Al-Ti alloy was formed to a thickness of 70 nm by sputtering to form a metal reflective layer 3. Obtained. Furthermore, a protective layer 4 was obtained by applying and curing a multifunctional epoxy acrylate-based ultraviolet curable paint by a spin coating method.
The thickness is about 1.2 mm. Example 6 Au was formed to a thickness of 890 nm on a metal reflective film by a sputtering method using the same recording layer 2 as in Example 4, and an optical recording medium was obtained in the same manner as in Example 4. Comparative Example 1 An optical recording medium was prepared in the same manner as in Example 1 except that a cyanine dye represented by the chemical formula (II-1) was used as a laser absorbing dye. Comparative Example 2 An optical recording medium was prepared in the same manner as in Example 1, except that a cyanine dye represented by the chemical formula (II-2) (NK4288 manufactured by Japan Photosensitive Dye Laboratories) was used as a laser absorbing dye. Comparative Example 3 As a laser absorbing dye, a cyanine dye represented by the chemical formula (II-2) and a cyanine dye represented by the chemical formula (II-3) (NK4400 manufactured by Japan Photographic Dye Laboratories) were used at a weight ratio of 2:
An optical recording medium was prepared in the same manner as in Example 1 except that the optical recording medium was used as a composite.

[0040]

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With respect to the obtained optical recording medium, the light reflectance and reproduction signal characteristics (C / N ratio, jitter, and error rate) were measured. The reproduction signal characteristic is a linear velocity of the disc of 3.3 m / s,
Using a semiconductor laser beam having a wavelength of 635 nm, the light was condensed at a numerical aperture (NA) of the objective lens of 0.60, recorded with recording Pw, and evaluated by an evaluation device. Initial characteristic test and reproduction deterioration characteristic test (after 1 × 10 ⁴ times) and high temperature and high humidity (70 ° C., 8
(0% relative humidity, 24 hours).

With respect to the initial characteristics, the optical recording medium of Comparative Example 1 was insensitive to semiconductor laser light of 635 nm and could not be evaluated. The initial characteristic of other optical recording media is that the light reflectance is 55%.
Larger, the S / N ratio was greater than 52 dB, and the error rate was less than 1 × 10 ⁻⁵ . The jitter of the optical recording media of Examples 1 to 4 was about 12%, while the optical recording media of Comparative Examples 2 and 3 showed values larger than 20%.

Tables 1 and 2 show the characteristic change rate after the reproduction deterioration and the characteristic change rate after the high temperature / high humidity weather test.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

According to the present invention, since the cyanine dye represented by the general formula (I) is used in the recording layer of the optical recording medium, the short wavelength (500 to 700 nm) compatibility of the cyanine dye and the chemical, Due to photochemical and thermal stability, the optical recording medium has sufficient sensitivity and light reflectance for short wavelength laser light,
In addition, the thermal interference between the pits and the heat accumulation in the high-density recording are prevented, the jitter component contained in the reproduction signal is small, the high-density recording is possible, the reproduction deterioration is small, and the long term reliability is excellent.
An optical recording medium conforming to the VD standard can be obtained.

In the above invention, since the oxygen quencher is contained in the recording layer in an amount of 1% or more, photodegradation of the cyanine dye due to ultraviolet light, laser light, or the like is prevented, and the light stability of the cyanine dye is increased. Thus, an optical recording medium having excellent long-term reliability can be obtained. Further, the optical recording medium using the cyanine dye represented by the general formula (I) for the recording layer is a thin film of a metal selected from the group consisting of Al, Au, Ag, Cu, Ni, Ti and chalcogenide metals on the metal reflective layer. Therefore, an optical recording medium having a high light reflectance for short wavelength light and a high sensitivity using short wavelength laser light can be obtained.

Further, since the optical recording medium using the cyanine dye represented by the general formula (I) for the recording layer has a one-sided, sticking or double-sided structure, it is easy to produce and has high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a one-sided optical recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a single-sided optical recording medium according to another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a sticking type optical recording medium according to another embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a double-sided optical recording medium according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Metal reflective layer 4 Protective layer 5 Adhesive layer 6 Deformation layer pit Non-groove substrate

Claims (8)

[Claims] 1. An optical recording medium formed mainly using a recording layer, a metal reflection layer, and a light-transmitting substrate that supports the recording layer and the metal reflection layer by being laminated on a main surface having a groove. In the optical recording medium, the recording layer is mainly composed of at least one of a cyanine-based dye represented by the following general formula (I) and is an organic dye thin film compatible with short-wavelength laser light. Embedded image [In the general formula (I), X ⁻ represents an iodide ion, a bromide ion, a perchlorate ion, a fluoroborate ion, a tetrafluorophosphate ion, a tetrafluoroantimonate ion, a methyl sulfate ion, or a methylbenzenesulfonic acid. Y ₁ represents an ion, _one of R ₁ and R ₂ represents a substituent having 3 to 18 carbon atoms having an unsaturated bond, and the other represents an alkyl group, an aryl group, or an alkoxyl group;
₁ and Y ₂ represent a hydrogen atom, an alkyl group, an aryl group, an alkoxyl group, a halogen atom, a nitro group, a hydroxyl group, a carboxyl group, a —OCF ₃ group, a —R ₃ OH group, a —R ₃ CO
OR ₄ group, -CH = CHCN group, -COOR ₄ group, -R ₃
COOH group, —COR ₃ group (wherein R ₃ is an alkylene group having 1 to 9 carbon atoms, R ₄ is an alkyl group having 1 to 9 carbon atoms) or a naphthalene ring which may be substituted by condensing with a benzene ring N and m are integers of 1 to 4, and (Y ₁ ) _n and (Y ₂ ) _m have mutually asymmetric structures in the cyanine dye molecule. ] 2. The optical recording medium according to claim 1, wherein the cyanine dye represented by the general formula (I) is a complex of two or more kinds. 3. The optical recording medium according to claim 1, wherein the recording layer contains 1% or more of an oxygen quencher. 4. A metal reflection layer having a high melting point and having an optical reflectance of 55% or more with respect to a short-wavelength laser beam, such as Al, Au, Ag, Cu, and N.
4. The optical recording medium according to claim 1, which is a thin film of a metal selected from the group consisting of i, Ti, and a chalcogenide-based metal. 5. A one-sided type wherein a recording layer and a metal reflective layer are sequentially laminated on a substrate, and a protective layer is further laminated.
An optical recording medium according to claim 1. 6. A one-sided substrate in which a recording layer and a metal reflective layer are sequentially laminated on a grooved substrate, and a protective layer is laminated, and a grooveless substrate is bonded with an adhesive. 5. The optical recording medium according to any one of items 1 to 4. 7. A sticking type in which a recording layer and a metal reflective layer are sequentially laminated on a substrate, and a two-sided type in which a protective layer is further laminated is laminated via a protective layer. Optical recording medium. 8. A double-sided type wherein a groove is formed on two main surfaces of a substrate which is a substrate, a recording layer and a metal reflective layer are sequentially laminated on the main surface, and a protective layer is further laminated. 5. The optical recording medium according to 4.