JP2633846B2 - Manufacturing method of optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing an optical recording medium that can be additionally recorded by using a focused beam of a semiconductor laser, and more particularly, to a computer external memory, an image,
The present invention relates to a method for manufacturing an optical recording medium used for recording various information such as audio.

(Prior art)

As the above-mentioned write-once optical recording medium, tellurium, tellurium alloy, a recording medium having an inorganic recording layer of a thin film of a low melting point metal such as a bismuth alloy, and, for example, US Patent No. 4,298,975
A recording medium using a phthalocyanine dye film as a recording layer as disclosed in the above publication has been proposed.

However, these recording media have low productivity because the recording layer needs to be formed in a vacuum such as vacuum evaporation and sputtering, and the medium having an inorganic recording layer has a large thermal conductivity of the recording layer. Therefore, there is a limit in terms of recording density.
In addition, since toxic substances such as tellurium are used, there is concern about toxicity. On the other hand, a medium having a phthalocyanine dye as a recording layer performs a process of exposing a recording film obtained by vapor deposition to heat or vapor of an organic solvent, that is, shifting, because the optical characteristics of the recording layer do not match the oscillation wavelength of the semiconductor laser. This shifting process is complicated, and requires a long process of 1 to 72 hours, so that it is not practically used.

In order to solve the above-mentioned problems, a medium in which a recording film is formed by a coating method using a soluble organic dye has been proposed. For example, a method of applying an organic dye soluble in an organic solvent and having an absorption in a semiconductor laser region, such as a diol metal complex, a polymethylene dye, a squarium dye or a naphthoquinone dye, by a spin coating method has been developed and has been partially put into practical use. . However, among the dyes proposed so far, a medium having a recording layer of, for example, a cyanine dye or a squarium dye has a drawback that the durability is poor. Further, since the reflectance of the dye film alone is essentially low as in the case of the dithiol metal complex, there is a problem that a reflective layer made of an inorganic compound such as a metal thin film or a metal oxide thin film is separately required.

Also, for example, U.S. Pat.No. 4,492,750 relates to a medium using an alkyl-substituted naphthalocyanine dye.In this patent, a reflective layer of Al or the like is provided on a glass or polymethyl methacrylate substrate, and a reflective layer such as Al is provided thereon. There is disclosed an optical recording medium provided with an optical recording layer composition in which alkyl-substituted naphthalocyanine dye particles having a particle diameter of 0.005 μm to 0.1 μm and subjected to an organic solvent vapor treatment are dispersed in a resin binder. As described above, the recording layer made of an organic dye cannot be directly formed on the substrate, and the reflection layer made of an inorganic compound such as Al is separately formed on the substrate separately from the recording layer by a vacuum process such as evaporation. The inability to obtain this makes the manufacturing process of the optical recording medium more complicated. Another problem is that organic dye films have low thermal conductivity, so that high recording sensitivity can be expected.However, metal or inorganic materials with high thermal conductivity are expected. When a reflective layer is provided, thermal energy generated by a writing laser beam applied to the recording layer is dissipated through the metal reflective layer due to the high thermal conductivity of the metal-based reflective layer, resulting in pits (signals). Since it is not effectively used for forming the corresponding irregularities, the recording sensitivity is greatly reduced. Further, when a reflective layer made of an inorganic compound such as Al is provided, when a laser beam for recording or reading a signal is irradiated from the substrate side, it is natural that even if the substrate itself is transparent, The laser beam is blocked by a metal reflective layer that does not substantially transmit light and does not reach the recording layer. Therefore, when a reflective layer is provided, recording / reproduction of a signal cannot necessarily be performed using a substrate or the like, and must be performed from the recording layer side. In such a case, even a small amount of dust or scratches on the surface of the recording layer greatly interferes with normal recording and reproduction of a signal having irregularities. Therefore, for practical use, an overcoat or the like is required as a protective layer on the recording layer. If recording and reproduction of signals can be performed by irradiating a laser beam through a transparent substrate, the presence of dust and scratches on the side where the laser beam is incident, that is, on the medium surface before the laser beam is focused Since the distance corresponding to the thickness of the signal does not substantially affect the recording / reproduction of a signal, a protective layer is not required.

However, in putting the optical recording medium into practical use,
Usually, the recording position is controlled optically, but in order to control the recording position optically, irregularities such as groups (guide grooves), wobble pits and pits for format signals are previously provided on the substrate on which the recording layer is provided. It is common to keep. Then, a dye liquid is applied on the substrate having the irregularities to form a recording film. However, the above-mentioned dithiol metal complex, polymethylene dye, squarium dye, naphthoquinone dye and the like can form the recording film itself by the coating method, but the guide groove (group) for controlling the recording position as described above. When applied to a thermoplastic resin substrate that has irregularities of the pre-format signal or the preformat signal (the irregularities are also made of thermoplastic resin), according to what we have examined, the tracking error signal often causes abnormalities, It has been found that there is a serious problem that the control and control of the signal may not be performed well, and the recording and reading of the signal may not be performed, or the pre-pit signal of the pre-format portion may not be read well. The group may have some sort of abnormality caused by the solvent used for It is but the details of which are of course unknown).

Therefore, in the case of the conventional organic dye described above, a flat thermoplastic resin substrate is formed separately on the substrate by forming irregularities such as guide grooves and preformat signals separately using a thermosetting resin such as an ultraviolet curable resin. Means for applying a dye solution has been employed.

However, forming irregularities using a thermosetting resin such as an ultraviolet curable resin as described above requires additional steps and is complicated, which is not preferable in terms of productivity and economy. From this point, when forming a recording film by a coating method, when forming a substrate, use of a thermoplastic resin substrate (substrate having a concave / convex portion also made of a thermoplastic resin) which is simultaneously provided with irregularities using a stamper or the like. There has been a strong demand for the development of a method that makes this possible.

[Basic idea]

The present inventors have conducted intensive studies to improve the above-mentioned drawbacks of an optical recording medium having an organic dye film as a recording layer. As a result, an organic recording medium comprising a specific phthalo / naphthalocyanine dye and a specific organic solvent was used. By using a dye solution, a recording layer can be formed by directly applying to a transparent thermoplastic resin substrate having guide grooves and irregularities for preformatting that could not be realized with conventional organic dyes, and the obtained results were obtained. In addition to the excellent durability of the optical recording medium, the recording layer itself has the function of a reflective layer, and thus it is possible to form an optical recording medium that does not require a separate reflective layer made of an inorganic compound as in the related art. Completed the invention.

[Disclosure of the Invention]

That is, the present invention relates to a method for manufacturing an optical recording medium capable of recording and reading out a signal with a light beam through a transparent substrate, wherein (a) the following general formula (I) [Wherein, M represents a metal or metalloid, -Y represents an organic substituent, n represents an integer of 1 or 2, L ₁ , L ₂ ,
L ₃ and L _{4 each} represent an unsubstituted or benzene ring or naphthalene ring skeleton having at least one substituent —Z. (B) a saturated aliphatic hydrocarbon, an unsaturated aliphatic hydrocarbon, a saturated alicyclic hydrocarbon, an unsaturated alicyclic hydrocarbon and a chain having a solubility parameter of less than 8.5; A solution dissolved in an organic solvent selected from ether is brought into contact with a transparent thermoplastic resin substrate having guide grooves and irregularities for a preformat signal,
Forming a recording layer containing a phthalo / naphthalocyanine dye represented by the general formula (I) on an uneven surface of the resin substrate, wherein a signal is formed without having a reflective layer made of an inorganic compound. Provided is a method for manufacturing an optical recording medium capable of performing recording and reading.

 Hereinafter, the present invention will be described in detail.

The transparent substrate used in the present invention preferably has a light transmittance of at least 85% for writing and reading signals and has a small optical anisotropy. This is because it is preferable to record and read out the signal with a light beam passing through the transparent resin substrate because the cover is less susceptible to dust and scratches. These transparent resin substrates have guide grooves for position control at the time of recording and reading, and irregularities for a preformat signal such as an address signal and various marks. It is preferable that the substrate is formed by using a stamper or the like at the time of molding (injection, compression, etc.) the substrate using a thermoplastic resin. The thickness of these resin substrates is not particularly limited, and may be plate-like or film-like, but usually about 50 μm to 5 mm is used. The shape may be circular or card-like, and its size is not particularly limited.

In the present invention, specific examples of the resin used for the transparent resin substrate include, for example, an acrylic resin, a polycarbonate resin, a polystyrene resin, a polyester resin, a polyamide resin, a vinyl chloride resin, a polyvinyl ester resin, and a polyolefin. Examples of preferable resins include thermoplastic resins such as a resin such as poly-4-methylpentene and a polyethersulfone resin. Among these, polycarbonate-based resins, acrylic-based resins, and polyolefin-based resins are particularly preferable in terms of the mechanical properties and optical properties of the substrate.

In the present invention, the following general formula (a) and the following general formula (I) [Wherein, M represents a metal or metalloid, -Y represents an organic substituent, n represents an integer of 1 or 2, L ₁ , L ₂ ,
L ₃ and L _{4 each} represent an unsubstituted or benzene ring or naphthalene ring skeleton having at least one substituent —Z. ) A solution obtained by dissolving the hetaro / naphthalocyanine dye shown in the above in an organic solvent having a solubility parameter of less than 8.5 is brought into contact with a transparent thermoplastic resin substrate having guide grooves and irregularities for a preformat signal by placing the liquid on the substrate. A recording layer comprising a phthalo / naphthalocyanine dye is provided.

In the present invention, the organic substituent represented by -Y in the phthalo / naphthalocyanine dye represented by the general formula (I) used in the recording layer includes carbon such as an aliphatic hydrocarbon group or an aromatic hydrocarbon group. A group comprising hydrogen; carbon and an enzyme other than hydrogen and carbon or hydrogen, including elements such as sulfur, nitrogen, silicon, halogen, boron, and phosphorus, such as an alkyloxy group, an aryloxy group, an alkylthioether group, and an arylthioether group , An alkylsiloxy group, an alkoxysiloxy group, an arylsiloxy group, an aryloxysiloxy group, a silyl group, an acyl group, a carboxylic ester group, a carboxylic amide group, an amino group, a sulfonamide group, an alkoxyalkyl group, and an aryloxyalkyl group , Halogenated alkyl group, halogenated aryl group, epoxy group, vinyl Organic substituent such; and polyether group, a polyamide group, a polyester group, polyurethane group, polysiloxy group, organic substituents, etc. of the polymer, such as poly epoxy group.

As more specific examples of the organic substituent -Y, examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a sec-butyl group, -Butyl group, iso-butyl group,
n-pentyl group, iso-pentyl group, sec-pentyl group,
tert-pentyl group, n-hexyl group, iso-hexyl group, 1-methyl-1-ethylpropyl group, 1,1-dimethylbutyl group, n-heptyl group, iso-heptyl group, sec
-Heptyl group, tert-heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group, cyclohexyl group, saturated aliphatic hydrocarbon group such as methylcyclohexyl group, allyl group, butene group, hexene Groups, octene groups, dodecene groups, cyclohexene groups, and unsaturated aliphatic hydrocarbon groups such as methylcyclohexene groups; and the aromatic hydrocarbon groups include phenyl, methylphenyl, ethylphenyl, dimethylphenyl, butylphenyl, Examples include a hexylphenyl group, a benzyl group, a phenylethyl group, a phenylhexyl group, a naphthalene group, a substituted naphthalene group, and an anthracene group.

Examples of the alkyloxy group and the aryloxy group include a methoxy group, an ethoxy group, a butoxy group, an octoxy group, a deteganoxy group, an allyloxy group, a phenoxy group, a dimethylphenoxy group, and a benzyloxy group; and the alkylthioether group and the arylthioether group include methylthio Group, ethylthio group, butylthio group,
Octylthio, dodecylthio, phenylthio, naphthylthio; alkylsiloxy, alkoxysiloxy, arylsiloxy and aryloxysiloxy groups include
Trimethylsiloxy group, triethylsiloxy group, tributylsiloxy group, trioctylsiloxy group, triphenylsiloxy group, trimethoxysiloxy group, triethoxysiloxy group, tributoxysiloxy group, trioctoxysiloxy group, triphenoxysiloxy group, dimethylmethoxy Siloxy, butyldimethoxysiloxy, diphenylmethoxysiloxy; silyl as trimethylsilyl, triethylsilyl, trioctylsilyl, triphenylsilyl; sulfonamide as dimethylsulfonamide, diethylsulfonamide Group, dibutylsulfonamide group, dioctylsulfonamide group, didodecylsulfonamide group, diphenylsulfonamide group, etc .; As the acyl group, acetyl group, ethylcarbonyl group Butyl group, an octyl group, a dodecyl group, a benzoyl group; Examples of the carboxylic acid ester group, a methoxycarbonyl group, an ethoxycarbonyl group, butoxycarbonyl group, octoxy group, dodecyloxy carbonyl group,
Benzoyloxy group and the like; Carboxyamide group includes a carboxamide group such as methyl carboxamide group, ethyl carboxamide group, butyl carboxamide group, octyl carboxamide group, dodecyl carboxamide group and phenyl carboxamide group; amino group Are dimethylamino, diethylamino, dibutylamino, dioctylamino, didodecylamino, diphenylamino, piperidine, piperazine, dimethylaminoethyl, dibutylaminoethyl, diphenylaminoethyl, etc .; alkoxyalkyl Groups and aryloxyalkyl groups such as methoxymethyl group, methoxyethyl group, ethoxyethyl group, butoxyethyl group, phenoxyethyl group, etc .; Chloromethyl group, chloroethyl group, chlorobutyl group, chlorooctyl group, chlordodecyl group, chlorophenyl group, chloronaphthalene group, polychloroalkyl group,
Polychloronaphthalene group, bromoethyl group, bromooctyl group, bromophenyl group, fluoroalkyl group, fluoroaryl group, polyfluoroalkyl group, polyfluoroaryl group and the like.

On the other hand, in the phthalo / naphthalocyanine dye represented by the general formula (I), the benzene ring or naphthalene ring represented by L ₁ , L ₂ , L ₃ or L ₄ may or may not have a substituent. As a specific example of the substituent -Z in the case where there is a substituent, for example, all the substituents -Y described above as specific examples of the organic substituent -Y are appropriate as specific examples of -Z. . In addition, as -Z, in addition to the organic substituent, a halogen, a hydroxyl group, a mercapto group, or the like may be further used.

On the other hand, M in the phthalo / naphthalocyanine dye represented by the general formula (I) is a trivalent or higher metal or metalloid, and specific examples thereof include II such as Al, Ga, In, and Tl.
Group I metal; Group IV metal such as Si, Ge, Sn, Pb, Ti, Zr, Hf; S
Group V metals such as b, Bi, V, Nb, Ta; Se, Te, Cr, Mo, W
Group VI metal such as Mn, Tc, etc .; Fe, Co, Ru, Rh, P
Group VIII metals such as d, Os, Ir, and Pt are included.

In the present invention, the phthalo represented by the general formula (I)
The naphthalocyanine dye is used by dissolving it in an organic solvent having a solubility parameter of less than 8.5. From the viewpoint of solubility in this organic solvent, it is represented by -Y in one molecule of the phthalo / naphthalocyanine dye of the general formula (I). The total number of organic substituents and all the substituents in the benzene ring or naphthalene ring represented by L ₁ , L ₂ , L ₃ and L ₄ -Z is 16
The above is preferable, 20 or more is more preferable, and 24 or more is particularly preferable. The upper limit of the total number of carbon atoms is not particularly limited, but is preferably 120 or less from the optical characteristics of the obtained recording film.

In the case of having a substituent -Z, there is no particular limitation on the method of introduction, and for example, even if it is contained in four benzene rings / or naphthalene rings of the phthalo / naphthalocyanine dye on average, One or more benzene rings or naphthalene rings may be introduced. There is no particular limitation on the bonding position. Further, the types of the substituents may be the same or different.

In the phthalo / naphthalocyanine dye of the present invention,
The expression “phthalo / naphthalo” refers to a specific combination of L ₁ , L ₂ , L ₃ and L _{4 in} the general formula (I), for example, when all are benzene rings [ie, the following general formula (II) )), When all are naphthalene rings [that is, the following general formula (III):
Or a combination of a mixture of a benzene ring and a naphthalene ring [for example, a phthalo / naphthalocyanine dye comprising two benzene rings and two naphthalene rings (in this case, particularly phthalo- A naphthalocyanine dye)),
It is meant to include all of these.

In addition, to make sure, the phthalo-naphthalocyanine dye represented by the general formula (IV) has already been proposed as an “asymmetric phthalo-naphthalocyanine dye” (for example, as filed on December 2, 1986) )

In the present invention, the phthalo represented by the general formula (I)
The naphthalocyanine dyes can be used alone or as a mixture of two or more.

Incidentally, the phthalonitrile / naphthalocyanine dye used in the present invention include, for example, JP 60-23451 Patent and Zn.Obs.Khim, 4
2 , 696-699 (1972) and the like, and can be easily synthesized according to known methods.

Next, the organic solvent used for dissolving the phthalo / naphthalocyanine dye described above in the present invention is preferably an organic solvent having a solubility parameter of less than 8.5. When an organic solvent with a solubility parameter of 8.5 or more is used, it depends on the type of organic solvent, application conditions, guide groove for recording position control, and the shape of the unevenness of the preformat signal. Can not do,
Preformatted signal cannot be read well,
Signal recording and reading may not be performed well, which is not preferable. It is presumed that some damage will probably occur to the group of substrates during application.

The solubility parameter in the present invention is represented by δ =
[(ΔH _^V -RT) / ^V _L] to a value determined by the equation (wherein [delta]: solubility parameter, [Delta] H ^V:: heat of vaporization, ^{V L.} Representing the molar volume), the boiling point by the [Delta] H ^V is Hildebrand rule Calculated ▲ ΔH ^V ₂₉₈ ▼ = 23.7Tb + 0.020Tb ² −
2950 (Tb: boiling point). Therefore, the solubility parameter is also set to a value of 298 ° K. Specific examples of the solubility parameter obtained from the boiling point by Hildebrandrule are, for example, Teruzo Asahara, Kodansha Publishing, Solvent Handbook 62-63
Partially described on the page. Also, Hindebrand rul
For the method of calculating the solubility parameter by e, see J.
H. Hildebrand, Solubility of Nonelectrolytes 424-4
27 (1950), and those described in Reinhold Publishing Co. and the like can be used.

Specific examples of the organic solvent having a solubility parameter of less than 8.5 used in the present invention include, for example, pentane, n-hexane, isohexane, 3-methyl-pentane, neohexane, 2,3-dimethylbutane, n-heptane, 2- Methyl hexane, 3-methyl hexane, 3-ethyl pentane, 2,2-dimethyl pentane, 2,3 dimethyl pentane, 2,
4-dimethylpentane, 3,3-dimethylpentane, 2,2,3
Saturated aliphatic hydrocarbons such as trimethylbutane, n-octane, isooctane and other isomers, nonane and its isomers, decane and its isomers, undecane and dodecane; pentene, hexene and its isomers, hexadiene and Unsaturated aliphatic carbons such as isomers, hexatriene, heptene and isomers, heptadiene and its isomers, heptatriene, octene and its isomers, octadiene, octatriene, nonene, nonadiene, nonatriene, decene, undecene, dodecene, etc. hydrogen;
Cyclopentane, methylcyclopentane, dimethylcyclopentane, ethylcyclopentane, cyclohexane,
Saturated alicyclic hydrocarbons such as methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, isopropylcyclohexane and cycloheptane; cyclopentene;
Cyclopentadiene, cyclohexene, methylcyclohexene, dimethylcyclohexene, ethylcyclohexene, cyclohexadiene, methylcyclohexadiene,
Unsaturated alicyclic hydrocarbons such as cycloheptene; terpene hydrocarbons; chain ethers such as diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, dipentyl ether;
Trichlorotrifluoroethane, propyl chloride and the like, among which saturated fatty acid hydrocarbons, unsaturated aliphatic hydrocarbons, saturated alicyclic hydrocarbons, unsaturated alicyclic hydrocarbons and chain ethers are preferred. Among them, those having a boiling point of 180 ° C. or lower are particularly preferable in view of ease of forming a recording layer. These solvents may be used alone or in combination of two or more.

The lower limit of the solubility parameter is not particularly limited, but is preferably 6.8 or more from the viewpoint of solubility in phthalo / naphthalocyanine dyes.

In the present invention, the above-mentioned solubility parameter is 8.5.
It is essential to use an organic solvent selected from less than saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, saturated alicyclic hydrocarbons, unsaturated alicyclic hydrocarbons and chain ethers. May be mixed with other solvents. For example,
A solvent having a solubility parameter of 8.5 or more may be used as a mixture with a solvent having a solubility parameter of less than 8.5. Specific examples of the solvent having a solubility parameter of 8.5 or more that can be used as a mixture include, for example, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; ethyl acetate, butyl acetate, amyl acetate, and ethylene glycol monoethyl ether acetate. Ester solvents such as acetone; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, and other ketone solvents; ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol;
Alcohol solvents such as ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, and benzyl alcohol; chloroform, carbon tetrachloride, methylene chloride, methyl chloroform, trichlene, tetrachloroethylene, dichloroethylene, dichloroethane, tetrachloroethane, tetrahydrofuran, dioxane; Diglyme, dimethylformamide and the like. Of course, when these solvents are used in combination with a solvent having a solubility parameter of 8.5 or more, the solubility parameter of the obtained mixed solvent is 8.
Needless to say, the mixing ratio must be adjusted so as to be less than 5.

In the present invention, in the case of using a mixture of solvents, the solubility parameter of the mixed solvent is determined by the sum of the product of the volume fraction of the mixed multiple solvents and the solubility parameter of each solvent, that is, the solubility parameter is obtained by the following formula (I). Value.

δ = V ₁ δ ₁ + V ₂ δ ₂ + V ₃ δ ₃ +... + V _n δ _n ... (1) where V ₁ , V ₂ , V ₃ ,..., V _n : each solvent in the mixed solvent Δ ₁ , δ ₂ , δ ₃ ,..., Δ _n : solubility parameter of each solvent in the mixed solvent The concentration of the dye solution in the present invention varies depending on the type of the solvent and the coating method, but is usually 0.1 to It is 10% by weight, preferably 0.3% to 5% by weight. At this time, in the present invention, in order to increase the reflectance of the recording film or to improve the sensitivity, other soluble dyes are not added to the dye solution in a range that does not impair the effects of the present invention. Mixing can be used within the range. Examples of the dyes that can be used in combination include known aromatic or unsaturated aliphatic diamine metal complexes, aromatic or unsaturated aliphatic dithiol metal complexes, polymethylene dyes, squarium dyes, naphthoquinone dyes, and anthraminone dyes. Soluble phthalo / naphthalocyanine dyes having no organic substituent on the dye or central metal are mentioned. When these dyes are added, a solvent that can dissolve both the dye and the dye of the present invention must be selected.

In the present invention, the phthalo / naphthalocyanine dye of the present invention and, if necessary, the phthalo / naphthalocyanine dye are used in order to enhance the smoothness of the recording film when forming the recording film and to reduce defects such as pinholes. Soluble resin such as nitrocellulose, ethylcellulose, acrylic resin, polystyrene, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinyl butyral, polyester resin, dimer acid polyamide, etc. An additive such as an agent may be added. However, when a large amount of these resins and additives are added, the reflectance of the recording layer is reduced, or the dye is not uniformly dissolved in the recording film to be in a dispersed state, and the recording sensitivity is reduced. descend. From these points, the addition amount of the resin and the additive is less than 20% by weight, preferably 10% by weight or less, more preferably 5% by weight or less in the recording film. In other words, in the present invention, the total amount of the phthalo / naphthalocyanine dye in the recording layer and the dye which can be used by mixing as described above is at least 80% by weight to 100% by weight, preferably 90% by weight. -100% by weight, more preferably 95-100% by weight.

In the method for manufacturing an optical recording medium of the present invention, for fixing (forming) a recording layer on a transparent substrate, for example, the dye solution comprising the above-mentioned phthalo / naphthalocyanine dye and an organic solvent is brought into contact with the substrate to apply the dye on the substrate. Can be established. More specifically, for example, after flowing down the dye solution on the substrate, or removing the excess liquid while rotating the substrate after pulling up after contacting the substrate surface with the interface of the dye solution, There is a method of causing the dye solution to flow down onto the substrate while rotating the substrate. At this time, the organic solvent used for dissolving the phthalo / naphthalocyanine dye in the recording layer depends on the kind of the organic solvent used, but since the thickness of the recording layer is very thin, the excess amount due to rotation or the like usually occurs. Conveniently substantially volatilizes upon removal of the liquid. However, if the volatilization of the solvent is insufficient, forcible drying may be performed thereafter.

In the optical recording medium manufactured by the method of the present invention, as described above, it is preferable to record and reproduce signals by using a laser light beam (a light beam irradiated from above the substrate) through a transparent substrate. In such a case, if the thickness of the recording layer is too large, the light for writing is absorbed as it passes through the thick recording layer and is considerably attenuated, so that the recording layer surface (the surface in contact with air) Does not reach enough. Therefore, the amount of light on this surface is insufficient, the temperature rise is insufficient, and it is not possible to satisfactorily form irregularities corresponding to signals. As a result, even if the sensitivity is lowered or the recording is managed, the S / N value (ratio of signal to noise) at the time of reading out the signal is too small to be practical.

On the other hand, if the thickness of the recording layer is too small, as described later, the reflectance of the recording layer cannot be sufficiently obtained due to light interference, and thus a large S / N value cannot be obtained.

Therefore, it is necessary to form a recording layer of an appropriate thickness, the thickness of the recording layer in the optical recording medium of the present invention is preferably 50 to 300 nm as a guide, more preferably 60 nm.
250250 nm.

There are various methods for measuring the film thickness, and it is quite difficult to obtain an accurate measurement value.However, in practicing the present invention, a value obtained by measuring a cross section of an ellipsometer or a medium with a microscope is used. It is preferred to use. Although it is particularly difficult to measure the film thickness when there is a guide groove on the substrate, it is sufficiently possible to substitute the film thickness of a portion of the same substrate having no pregroove such as the guide groove.

One feature of the present invention is that a recording layer can be formed by directly applying a dye or the like to a thermoplastic resin substrate having irregularities such as pregrooves and prepits.

Conventionally, when a recording film is formed by applying a dye solution, it is necessary to use a substrate provided with a thermosetting resin such as an ultraviolet curable resin for unevenness such as pregrooves and prepits. Adding irregularities such as pre-grooves and pre-pits using a thermosetting resin not only increases the number of steps but also increases the error rate, which is the most important performance for displaying the characteristics of the memory medium, by increasing the number of steps. It goes without saying that the present invention has a tremendous significance in this respect.

Yet another feature of the present invention is that the recording layer thus formed has a considerably high reflectance by itself, and therefore, the recording layer itself simultaneously serves as a reflection layer. It also has a function.

Therefore, the optical recording medium produced by the method of the present invention, when recording or reading a signal without providing a reflective layer made of an inorganic compound such as a metal thin film or a metal oxide or a metal alloy film, in particular, as in the past, This makes it possible to control the focus of the laser beam and the track of the signal writing position.

Generally, to write a signal on an optical recording medium, the recording layer is focused and irradiated with a laser beam. The dye in the recording layer of the irradiated portion absorbs the laser beam and generates heat, so that the recording layer is deteriorated, irregularities are formed, and the reflectance changes, whereby writing is performed. A signal is read out by detecting the change in the reflectance with laser beam light. Generally, if the change in the reflectance is small, the signal-to-noise ratio (S / N) is small, which is not preferable.

It should be noted here that the manner of change (mode) of the reflectivity of the optical recording medium when recording is performed, that is, the manner of change of the reflectivity when irregularities are formed, depends on the optical recording medium. This is completely different depending on the configuration of the recording layer of the medium. For example, in the case of a medium composed of two layers, a light reflection layer and a light absorption layer, as disclosed in U.S. Pat. No. 4,219,826, the medium was covered with the light absorption layer by forming irregularities in the light absorption layer. The reflective layer is exposed, and therefore, after recording, the reflectance of the uneven portion increases. Therefore, in such a case, it is sufficient that the initial reflectance (that is, before the unevenness is formed) is such that the laser beam can be controlled. On the other hand, in the case of an optical recording medium having a so-called monolayer in which a recording layer has both a light reflectance and a light absorption layer without a reflective layer as in the present invention, the situation is completely reversed, and the formation of unevenness causes the situation to be completely reversed. The reflectivity of the part decreases. That is, the reflectance of the uneven portion is lower than the initial reflectance originally possessed by the recording layer. In such a case, in order to obtain a large S / N ratio value, the original reflectance through the substrate is at least 10% or more, preferably 15% or more, more preferably 20% or more before the signal is written. That is all. The reflectance of 10% or more, preferably 15% or more, more preferably 20% or more uses the dye of the present invention and appropriately selects the thickness of the recording layer (the reflectance is measured from the front and back of the recording layer). It varies depending on the film thickness due to interference due to reflected light, etc.).

The reflectance in the present invention is the same as the oscillation wavelength of a semiconductor laser used for recording and reading (for example, 830 nm).
m) Using a light source and fixing the recording layer on a transparent substrate that has no irregularities such as guide grooves, the value measured through a transparent substrate using a spectrophotometer equipped with 5 ゜ regular reflection accessory equipment Shall mean.

The medium of the present invention has a sufficient reflectance in the oscillation wavelength region of the semiconductor laser and a large absorption in the wavelength region, as described above, using only the dye single-layer film as the recording layer.

As disclosed in U.S. Pat. No. 4,492,750, in the region where the amount of the resin binder is as high as 40 to 99% by weight, preferably 60 to 90% by weight, the dye is not uniformly dissolved in the binder and the dye particles are dispersed. If the organic solvent vapor treatment is not performed, the spectral characteristics of the dye will not match the laser oscillation wavelength. On the other hand, in a region where the amount of the resin binder is much less than 2 to 20% by weight as in the present invention, the organic solvent vapor treatment is not performed despite the fact that a similar dye is used unexpectedly. However, we have found that it has large absorption in the laser oscillation wavelength range. The reason for this is not exactly known, but it is considered that the association state or crystal structure between the dye molecules is likely to vary greatly depending on the amount of the resin binder.

In the present invention, as a further significant feature, it is possible to form a recording layer substantially using only a phthalo / naphthalocyanine dye without substantially using a resin binder (binder). Usually, when a film of an organic dye alone is prepared by vacuum deposition or the like, the obtained film is inferior in mechanical strength. Therefore, a large amount of resin was added to the organic dye as a binder to improve the mechanical strength of the dye film.
Certain dyes of the present invention have substantially less phthalo /
A recording film made of a naphthalocyanine dye alone often has sufficient mechanical strength to be used as an optical recording medium.
It is considered that the reason is that by using an organic solvent having a solubility parameter of less than 8.5, the surface of the thermoplastic resin substrate was affected by the solvent and the adhesion between the dye and the substrate was improved.

In putting the optical recording medium of the present invention into practical use, an antireflection layer is provided to improve the S / N value, or an ultraviolet curable resin or the like is applied on the recording layer for the purpose of protecting the recording layer. Alternatively, a protective sheet may be attached to the recording layer surface, or two sheets may be attached to each other with the recording layer surface inside. It is preferable to provide an air gap on the recording layer when bonding.

In the present invention, the laser light used for recording and reading is 730 to 870 nm, preferably 780 to 850
A semiconductor laser having an oscillation wavelength in nm. For example, when recording at 5 m / s, the laser output on the substrate surface may be about 4 mW to 12 mW, and the read output may be about 1/10 of the recording time, about 0.4 mW to 1.2 mW. It is.

[Preferred embodiment for carrying out the invention]

Hereinafter, examples of preferred embodiments of the present invention will be described with reference to examples.

Example 1 (1) A surface having a guide groove of a polycarbonate resin plate provided with a spiral guide groove (depth 70 nm, width 0.6 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 130 mm at the time of injection molding of a substrate. A solution consisting of 3.0 parts by weight of tetra-tert-amyl-naphthalocyanine-phenylindium dye and 97 parts by weight of octane (solubility parameter 7.54) was dropped at the center, and the polycarbonate resin plate was rotated at a speed of 1000 rpm for 10 seconds. Next, this polycarbonate resin plate
After drying in an atmosphere at 40 ° C. for 10 minutes, a recording layer consisting essentially of only tetra-tert-amyl-naphthalocyanine-phenylindium dye was fixed on the polycarbonate resin plate.
The thickness of this recording layer was 100 nm as measured on a cross section with a microscope. The reflectance of light having a wavelength of 830 nm through the polycarbonate resin plate was 27%.

Next, a substrate (recording plate) on which the recording layer is fixed and a protective plate (a polycarbonate resin substrate having a diameter of 130 mm, a thickness of 1.2 mm, a convex portion having a width of 3 mm and a height of 500 μm at a position of an outermost periphery and a radius of 15 mm). An adhesive was applied to the protruding portion of the protective plate with the dye film side facing inward to produce an optical recording medium having an air gap structure.

(2) The optical recording medium thus produced is placed on a turntable with the substrate (recording plate) on which the recording film is fixed facing down,
Using an optical head equipped with a semiconductor laser having an oscillation wavelength of 830 nm and an output of 8 mW on the substrate surface while rotating at a speed of 900 rpm, a laser beam is focused on the recording layer from the lower side of the optical recording medium through the polycarbonate resin plate. 1MHz pulse signal (duty50
%) Was recorded. Next, using the same apparatus, the output of the semiconductor laser was set to 0.7 mW on the substrate surface, and the recorded signal was reproduced in the same manner. At this time, the signal-to-noise ratio (S / N) was 53 dB, so that extremely good signal writing and reading could be performed.

(3) In order to examine the durability of this optical recording medium, a temperature of 60 ° C. and 90 ° C.
After being left for four months in an atmosphere of% RH, signals were recorded on the unrecorded portion in the same manner as described above, and a signal recorded before the durability test and a signal recorded after the durability test were reproduced. However, S / N ratios of 51 and 52 dB were obtained, respectively, and the change in the durability test was sufficiently small.

(4) The shape of the pits in the signal recording area after the durability test was observed with a scanning electron microscope. The pits recorded before and after the durability test had substantially the same shape. It is considered that the thermal conductivity is large in an optical recording medium having a recording layer of an inorganic thin film such as a Te-based material, and the rise of the pit edge which causes noise is hardly seen in the case of the present medium. It was confirmed that the pit shape was very clean.

Comparative Example 1 An optical recording medium was produced in the same manner as in Example 1 except that carbon tetrachloride (solubility parameter 8.6) was used instead of octane. The thickness of the recording layer of this medium,
The reflectance was almost the same as that of the medium of Example 1. Next, a recording / reproducing test was performed using this medium in the same manner as in Example 1. However, there was a part where the track servo at the time of recording could not be performed properly and the recording could not be performed, and the tracking error signal of the part was monitored. It was very disturbed.

Example 2, Comparative Example 2 Using the polycarbonate resin substrate used in Example 1,
Using a naphthalocyanine dye having four substituents, M and -Y and an organic solvent shown in Table 1, an optical recording medium was prepared in the same manner as in Example 1, and the reflectance and S / N value were examined. The results are summarized in Table 1.

As is clear from Table 1, in the example of the present invention, recording and reading of signals were sufficiently performed, and the S / value was obtained at 48 db or more. There was a portion where recording was not possible, and the tracking error signal in that portion was disturbed.

Example 3 Phthalo / naphthalocyanine dyes shown in Table 2
An optical recording medium was prepared and evaluated in the same manner as in Example 1 except that a laser having the oscillation wavelength shown in the table was used for recording and reading. The phthalo / naphthalocyanine dyes in Table 2 are represented as “substituent-phthalo (l) / substituent-naphthalo (m) cyanine.Y (n) -M”, and 1 and m Represents the number of benzene rings and naphthalene rings contained in one phthalo / naphthalocyanine molecule, respectively. Therefore, it is natural that l + m = 4. M represents a central metal or semimetal, Y represents a substituent of M (central metal or semimetal), and n represents its number.

Example 4 and Comparative Example 3 A medium was prepared and evaluated in the same manner as in Example 1 except that the organic solvents shown in Table 3 were used. The results are summarized in Table 3.
As is clear from Table 3, in the case of a mixed solvent system, when a solvent having a solubility parameter of less than 8.5 was used as in the example of the present invention, signal recording and reading could be performed well, and large S Although a / N value could be obtained, when a solvent having a solubility parameter of 8.5 or more was used, there was a portion where a signal could not be recorded as in Comparative Example 1.

〔The invention's effect〕

As described above, in the present invention, a recording layer can be formed by directly applying a dye solution to a thermoplastic resin substrate having irregularities. Further, the optical recording medium of the present invention thus manufactured performs writing and reading of signals without providing a reflective layer of a metal thin film or a metal compound thin film since the recording layer itself has a sufficient reflectance. Can be big
The S / N value is obtained. Further, the optical recording device produced according to the present invention The recording medium is stable against heat and humidity and can be used for a long time.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-122787 (JP, A) JP-A-61-197281 (JP, A) JP-A-62-64597 (JP, A) JP-A 62-122597 233288 (JP, A) JP-A-63-39388 (JP, A) JP-A-63-94893 (JP, A) JP-A-63-119036 (JP, A)

Claims (6)

(57) [Claims] 1. A method of manufacturing an optical recording medium capable of recording and reading a signal by a light beam passing through a transparent substrate, comprising: (a) the following general formula (I): [Wherein, M represents a metal or metalloid, -Y represents an organic substituent, n represents an integer of 1 or 2, L ₁ , L ₂ , L
₃ and L ₄ represent an unsubstituted or benzene ring or naphthalene ring skeleton having one or more substituents -Z. Here, the substituent -Z represents an organic substituent -Y, a halogen, a hydroxyl group or a mercapto group. (B) a saturated aliphatic hydrocarbon, an unsaturated aliphatic hydrocarbon, a saturated alicyclic hydrocarbon, an unsaturated alicyclic hydrocarbon and a chain having a solubility parameter of less than 8.5; A solution dissolved in an organic solvent selected from ether is brought into contact with a transparent thermoplastic resin substrate having guide grooves and irregularities for a preformat signal, and the surface of the resin substrate having irregularities is represented by the general formula (I). A method for producing an optical recording medium capable of recording and reading signals without having a reflective layer made of an inorganic compound, comprising forming a recording layer containing a phthalo / naphthalocyanine dye represented as above. 2. In the phthalo / naphthalocyanine dye represented by the general formula (I), the number of carbon atoms in all the organic substituents -Y contained in one molecule and L ₁ , L ₂ , L ₃ , L ₄ The method according to claim 1, wherein the total number of carbon atoms in all the substituents -Z in the benzene ring or naphthalene ring represented by the formula is 16 to 120. 3. In the phthalo / naphthalocyanine dye represented by the general formula (I), the number of carbon atoms in all organic substituents -Y contained in one molecule and L ₁ , L ₂ , L ₃ , L ₄ 3. The method according to claim 2, wherein the total number of carbon atoms in all the substituents -Z in the benzene ring or naphthalene ring represented by the formula is 20 to 120. 4. In the phthalo / naphthalocyanine dye represented by the general formula (I), the number of carbon atoms in all the organic substituents -Y contained in one molecule and L ₁ , L ₂ , L ₃ , L ₄ 4. The method according to claim 3, wherein the total number of carbon atoms in all the substituents -Z in the benzene ring or naphthalene ring represented by the formula is from 24 to 120. 5. The method according to claim 1, wherein the unevenness of the resin substrate is formed by a thermoplastic resin. 6. The method according to claim 5, wherein said irregularities are formed simultaneously when forming the substrate.