JPH0376239B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention utilizes changes in reflectance or transmittance that occur when the energy ray irradiated portion of the recording layer is deformed or removed by melting or the like by irradiating energy rays such as laser light. The present invention relates to a recording medium suitable for optically recording and reproducing information. The properties required of optical recording media such as optical disks include high recording sensitivity in the wavelength range of the laser used as the recording light source, high signal-to-noise ratio of the reproduced signal, high recording density, and storage stability. It has excellent properties and low toxicity. In so-called heat mode recording media, in which the recording layer melts and forms pits due to the temperature rise of the laser beam irradiation area, in order to increase the recording sensitivity, the recording layer must have a high spectral absorption rate, melting point, specific heat It is also necessary that the recording layer has low thermal conductivity, and it is desirable that the recording layer be thin. In order to increase the signal-to-noise ratio of the reproduced signal, it is necessary to make sure that the pits have the same shape and size, and that there is no disturbance around the pits.If reflected light is used for reproduction, it is necessary to In addition, in order to increase the recording density, the thermal conductivity is required to be low.
Furthermore, in order to obtain a recording medium with excellent storage stability, the recording layer is required to have high oxidation stability and moisture resistance. The best recording medium for lasers at present is one in which a thin film of tellurium or a tellurium alloy such as a tellurium-arsenic alloy is formed as a recording layer on a glass or plastic substrate. Tellurium and tellurium alloy thin films have high light absorption in the visible to near-infrared wavelength region, low thermal conductivity, and low melting point, so they have high recording sensitivity, and the shape and size of the pits are easy to match, and the visible to near infrared wavelength range is high. It has an appropriate reflectance in the near-infrared wavelength region, so it can be easily detected by reflected light.
It has properties suitable for heat mode laser recording media, such as the ability to obtain reproduced signals with a high signal-to-noise ratio. However, tellurium thin films and tellurium-arsenic alloy thin films have drawbacks such as low oxidation stability and high toxicity. Attempts have been made to improve oxidation stability by adding selenium to tellurium or tellurium-arsenic alloys, or by using low tellurium oxides.
To date, sufficient quantities have not been obtained, and no effective measures have been found regarding toxicity. Advantages compared to tellurium-based recording media in terms of toxicity include glass or plastic substrates;
Alternatively, there is a recording medium in which a dye or a layer in which a dye is dispersed in a polymer is formed on a reflective layer made of aluminum or the like provided on the substrate. However, the absorption wavelength of dyes is generally on the shorter wavelength side than red light, and dyes are stable dyes that exhibit large absorption in the 750 nm to 850 nm oscillation wavelength region, which is the oscillation wavelength range of semiconductor lasers, which are expected to become the mainstream of recording light sources in the future. Since a dye cannot be obtained, a practical dye-based recording medium using a semiconductor laser as a recording light source has not been obtained. The inventors of the present invention have carried out intensive research with the aim of completing an optical recording medium with low toxicity, excellent oxidation stability, and water resistance. Energy rays such as ultraviolet rays are irradiated, and a recording layer consisting of a composite layer in which metal or semiconductor fine particles are dispersed in a metal oxide thin film, or a metal or semiconductor thin film and a metal oxide thin film is formed on the ultraviolet irradiated surface. The inventors have discovered that by forming alternately laminated recording layers, it is possible to obtain an optical recording medium that is highly sensitive, has an extremely high signal-to-noise ratio, is stable, and has low toxicity, and has thus arrived at the present invention. The gist of the present invention is an optical recording device characterized in that a recording layer made of a metal or a semiconductor and a metal oxide is provided on the energy ray irradiated surface of an organic polymer layer irradiated with energy rays. It lies in the mechanism and composition of the medium. FIG. 1 shows an example of the layer structure of the optical recording medium of the present invention. In FIG. 1, a recording layer 1 made of a metal or a semiconductor and a metal oxide is provided on a surface 4 of an organic polymer layer 2 formed on a substrate 3 and irradiated with energy rays such as ultraviolet rays. In this optical recording medium, energy rays such as laser beams incident from the substrate side or the opposite side to the substrate are absorbed by the recording layer, and the generated heat melts or fluidizes the recording layer, forming pits. The resulting light reflectance of the recording layer portion of the medium that is irradiated with energy rays and the recording layer portion that is not irradiated with energy rays,
Recording and reproduction are performed using changes in optical properties such as transmittance. The organic high molecular weight material used in the optical recording medium of the present invention has a property that a part of the main chain is easily cut off by irradiation with energy rays such as ultraviolet rays, and the average molecular weight decreases. Methyl methacrylate, a copolymer of methyl methacrylate and a vinyl monomer copolymerizable with it, polystyrene, a copolymer of styrene and a vinyl monomer copolymerizable with it, polyacrylonitrile,
Examples include acrylonitrile and copolymers of vinyl monomers copolymerizable with acrylonitrile. In particular, when a methyl methacrylate polymer or a styrene polymer is used, an optical recording medium with high sensitivity and a high signal-to-noise ratio can be obtained. Examples of vinyl monomers that can be copolymerized with methyl methacrylate include acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, and methacrylic acid alkyl esters such as ethyl methacrylate, propyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. Esters, aromatic vinyl monomers such as styrene, α-methylstyrene and p-chlorostyrene, unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, dimethyl fumarate, dibutyl fumarate, dimethyl maleate, Dialkyl esters of unsaturated dicarboxylic acids such as dibutyl maleate,
Examples include vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, and chlorine-containing vinyl monomers such as vinyl chloride and vinylidene chloride. Examples of vinyl monomers that can be copolymerized with styrene include alkyl esters of methacrylic acid or acrylic acid such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methyl acrylate, and ethyl acrylate, and acrylonitrile. , unsaturated nitrile monomers such as methacrylonitrile, α-methylstyrene, m-methylstyrene, p-methylstyrene, o-chlorostyrene, m-chlorostyrene,
Examples include aromatic vinyl monomers such as p-chlorostyrene, unsaturated carboxylic acids such as maleic anhydride, and the like. The thickness of the organic polymer layer needs to be 500 Å or more. The thickness of the organic polymer layer is 500
If it is less than Å, an optical recording medium with high sensitivity and high signal-to-noise ratio cannot be obtained. Examples of energy rays irradiated to the organic polymer layer of the optical recording medium of the present invention include:
Examples include ultraviolet rays, electron beams, and X-rays, but especially when irradiated with ultraviolet rays with a wavelength of 190 to 420 nm at a dose of 10 mJ/cm ² or more, an optical recording medium with excellent sensitivity and signal-to-noise ratio can be obtained. Examples of metals or semiconductors used in the recording layer of the optical recording medium of the present invention include Sn, In,
Ge, Sb, Pb, Al, Zn, Cu, Ag, Au, Bi, Se,
Examples of preferred metals or semiconductors from the viewpoint of low toxicity are Sn, In, Ge, Sb, Pb, Al,
Examples include Zn, Cu, Ag, Au, and alloys containing these as main components. The characteristics of the above metals or semiconductors include high reflectance in the oscillation wavelength range of semiconductor lasers, low melting point, low toxicity, and high stability in air, so these metals or semiconductors are the main components. When using such an alloy, care must be taken not to lose the above characteristics. The metal oxide used in the recording layer of the optical recording medium of the present invention must have excellent chemical stability and low thermal conductivity. Preferred examples include Sn, In, Al, Examples include Zr and Zn oxides, but especially Sn or In oxides have excellent stability in air and provide high sensitivity and reproduction signal.
A recording medium with a high SN ratio can be obtained. Examples of Sn or In oxides include the chemical formulas SnO ₂ , InO ₃ and
Low oxides such as SnO _2-x , In ₂ O _3-x , Sn _1-y M _y O ₂ ,
Examples include SnO ₂ such as In _2-Z N _Z O ₃ and In ₂ O ₃ doped with a different metal. Here x and z are
0.5 or less, y is a positive number of 0.25 or less, M is Sb, In,
N represents a metal such as Sn, Ge, Pb, or Zn. The recording layer in the optical recording medium of the present invention is made of a composite layer in which the metal or semiconductor fine particles are dispersed in the metal oxide thin film, or a laminated film of the metal or semiconductor thin film and the metal oxide thin film. However, especially when a composite layer in which the metal or semiconductor fine particles are dispersed in the metal oxide thin film is used in the recording layer, an optical recording medium with high sensitivity and a high signal-to-noise ratio can be obtained. The filling rate of metal or semiconductor fine particles in the composite layer is preferably 0.3 or more and 0.95 or less. If the filling rate is less than 0.3,
There is a tendency that the absorption coefficient of the composite layer for energy rays such as laser light decreases, and the temperature at which the composite layer melts and fluidizes increases, resulting in a decrease in the recording sensitivity of the resulting optical recording medium. When the filling factor exceeds 0.95, contact between the metal or semiconductor particles dispersed in the composite layer begins, and the particle size of the metal or semiconductor increases, resulting in irregularities in the size and shape of the recording pits, resulting in SN There is a tendency for the ratio to decrease,
Furthermore, since the thermal conductivity of the composite layer also increases, recording sensitivity tends to decrease. In the optical recording medium of the present invention, when a composite layer in which the above-mentioned metal or semiconductor fine particles are dispersed in a metal oxide is used in the recording layer, for the purpose of increasing the sensitivity and the contrast between the recording part and the end recording part. The recording layer can also be formed by laminating composite layers of different types of metals, semiconductors, and oxides, or by laminating the composite layer and a thin film of the metal or semiconductor. In the optical recording medium of the present invention, the thickness of the recording layer is
The thickness is preferably 50 Å or more, preferably 2000 Å or more. When the thickness of the recording layer exceeds 2000 Å, the volume of the area of the recording layer irradiated with energy rays increases, which reduces the density of energy absorbed when irradiated with energy rays, resulting in a decrease in the recording sensitivity of the recording medium. Furthermore, the shape around the formed pit becomes easily disordered, making it difficult to increase the signal-to-noise ratio. When the thickness of the recording layer is 50 Å or less, the difference in reflectance or transmittance between the recording part and the end recording part of the recording medium becomes small.
Since the contrast is low, it is difficult to increase the signal-to-noise ratio. When the optical recording medium of the present invention is used in a reflective optical disk, a more preferable thickness range of the recording layer is 100 Å or more and 1000 Å or less. In one embodiment of the optical recording medium of the present invention, an organic polymer layer is provided on a substrate, and after irradiating the organic polymer layer with energy rays such as ultraviolet rays, the organic polymer layer is exposed to energy rays such as ultraviolet rays. A recording layer is formed on the irradiation side surface. The substrate may be a metal plate such as aluminum, a glass plate, methyl methacrylate polymer, styrene polymer, polyvinyl chloride, polycarbonate, polyethylene terephthalate, polybutylene terephthalate,
Polyamide and epoxy resins, diallyl phthalate polymers, diethylene glycol bisallyl carbonate polymers, polyphenylene sulfide,
A sheet or film of thermoplastic or thermosetting resin such as polyphenylene oxide or polyimide is used. In particular, the substrate may contain organic polymers such as polymethyl methacrylate, a copolymer of methyl methacrylate and a vinyl monomer copolymerizable with it, polystyrene, or a copolymer of styrene and a vinyl monomer copolymerizable with it. When using a molecular weight material, after irradiating the surface of this substrate with energy rays such as ultraviolet rays, a recording layer is formed on the surface of the substrate that has been irradiated with energy rays, and an organic polymer layer is then used. The optical recording medium of the present invention having the structure shown in FIG. 2 can be obtained without any process. Furthermore, when using an organic high molecular weight material as described above for the substrate, a substrate having pre-groups on the surface is manufactured by performing cast polymerization, compression molding or injection molding using a mold or stamper, and then the pre-groups of the substrate are produced. The optical recording medium of the present invention can be obtained by irradiating energy rays such as ultraviolet rays onto the surface where the groups are formed and then forming a recording layer on the irradiated surface. When the optical recording medium of the present invention is used as an optical disk in which recording light and reproduction light are incident through a substrate, the substrate may be a glass plate, or a methyl methacrylate polymer, a styrene polymer, or a polychloride polymer. It is necessary to use a sheet of transparent plastic such as vinyl, diethylene glycol bisallyl carbonate polymer, or epoxy resin. The method for manufacturing a recording medium of the present invention will be explained below using exemplary diagrams of the layer structure. In the recording medium having the structure shown in FIG. 1, an organic polymer layer 2 is coated on a substrate 3, and then energy rays such as ultraviolet rays are irradiated from above the figure, and a recording layer is formed on the surface 4 irradiated with the energy rays. It can be obtained by forming 1. In order to coat the substrate 3 with the organic polymer layer 2, the organic polymer may be dissolved in a solvent or emulsion-formed using a method such as spin coating, roll coating or dip coating, physical vapor deposition, A method such as plasma polymerization is used. After coating the organic polymer layer 2,
This layer is irradiated with energy rays. As a specific example, a xenon-mercury lamp, a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, etc. are used as the energy source,
Irradiate at least 10 mJ/cm ² of ultraviolet light with a wavelength of 190 to 420 nm. The intensity of ultraviolet rays is determined by the surface of the organic polymer layer.
It is desirable that it is 10 mw/cm ² or more. When using ultraviolet rays as energy rays as mentioned above,
In particular, if a xenon-mercury lamp, high-pressure mercury lamp, or the like, which has a wavelength of 300 nm or less and has a large spectral output, is used as a radiation source, an optical recording medium with excellent recording sensitivity and signal-to-noise ratio can be obtained.
Furthermore, when substances generally called photopolymerization initiators and photosensitizers are added to the organic polymer layer, 300 nm
Even when using a radiation source with a small spectral output at the following wavelengths, it is possible to obtain an optical recording medium with excellent recording sensitivity and signal-to-noise ratio. Examples of the photopolymerization initiator and photosensitizer include benzoin isobutyl ether,
Benzoin alkyl ethers such as benzoin isopropyl ether, 2,2-dimethoxy-2,
Benzyl ketals such as phenylacetophenone, acetophenone derivatives such as diethoxyacetophenone, benzophenone, benzyl, methyl-
Examples include ketones such as o-benzoin benzoate. The amount of UV irradiation should be 10mJ/ ^cm2 or more,
Although there is no particular upper limit, when manufacturing an optical recording medium with the structure shown in Figure 2 using an organic high molecular weight material such as polymethyl methacrylate for the substrate, the mechanical strength of the substrate may decrease due to ultraviolet irradiation. Care must be taken to avoid deformation due to heat. In this case, by using a xenon-mercury lamp or a high-pressure mercury lamp as the radiation source and selecting the irradiation dose appropriately, recording with high sensitivity and high signal-to-noise ratio can be achieved without reducing the mechanical strength or deforming the substrate. A medium is obtained. The optical recording medium of the present invention can be obtained by irradiating an organic polymer layer provided on a substrate with energy rays as described above, and then forming a recording layer on the surface irradiated with energy rays. To form the recording layer, a vacuum deposition method, an ionization deposition method, an ion plating method, a cluster ion beam deposition method, a sputtering method, etc. are used. When using a composite layer in which fine metal or semiconductor particles are dispersed in a metal oxide as a recording layer, the metal or semiconductor and the metal oxide are placed in separate crucibles and placed in a vacuum of 1 x 10 ^-3 mmHg or less. evaporation and deposition at the same time. It is also possible to use an ion plating method in which ionized particles are accelerated by applying a DC voltage to the substrate side at the same time as ionization. Composite layers can also be formed by simultaneous sputtering using a metal or edge conductor target and a metal oxide target. In any case, when forming a composite layer, a composite layer having a predetermined metal or semiconductor filling rate and thickness can be obtained by separately controlling the vapor deposition rate and sputtering rate of the metal or semiconductor and metal oxide. When using a recording layer in which thin films of metal or semiconductor and thin films of metal oxide are alternately laminated, the metal or semiconductor and metal oxide are alternately deposited or sputtered using the same method as when forming a composite layer. By doing so, a recording layer is formed. The recording layer in the optical recording medium of the present invention is extremely stable under normal environments, and there is no need to provide a protective layer, but protection against mechanical shock, etc.
A protective layer can be provided on the recording layer for the purpose of preventing problems in recording and reproduction due to adhesion of dust and the like. As a protective layer, SiO ₂ ,
Inorganic materials and organic polymer materials such as Al ₂ O ₃ and TiO ₂ are used. In the optical recording medium of the present invention shown in FIGS. 1 and 2, when the organic polymer layer 2 and the substrate 3 are transparent, the recording light and the reproducing light are incident from above the diagram. The light may also be incident from below. The optical recording medium of the present invention has low toxicity and high sensitivity,
Excellent stability in air and SN
It is characterized by an extremely high ratio. Although the reason why the optical recording medium of the present invention exhibits the above-mentioned excellent characteristics is not necessarily clear at present, it can be estimated as follows. When the organic polymer layer in the optical recording medium of the present invention is irradiated with energy rays such as ultraviolet rays, the main chain is cut, especially near the surface irradiated with the energy rays, and the molecular weight is reduced. The surface energy decreases as the surface energy decreases. On the other hand, recording pits are formed by moving the recording layer that has been melted or fluidized by irradiation with energy rays such as laser light. Since the surface energy of the organic polymer layer is low, the difference in surface energy between this layer and the melted or fluidized recording layer becomes large.
It is thought that the melted or fluidized recording layer moves smoothly. Alternatively, when the recording layer is irradiated with laser light, if the energy of the laser light melts the portion of the organic polymer layer whose molecular weight has been reduced by energy ray irradiation, the laser light irradiation may melt or fluidize the part. It is also conceivable that the particles may move together with the deposited recording layer and become susceptible to pit formation. As a result, pits with uniform shape and size are formed with low irradiation energy, resulting in an optical recording medium with high sensitivity and high signal-to-noise ratio. Furthermore, since the metals, semiconductors, metal oxides, etc. used in the recording layer of the optical recording medium of the present invention are all stable in air and water and have low toxicity, the optical recording medium of the present invention
As an optical disk for recording and reproduction, it can be used not only as an image file, document file, data file, and external memory of a computer, but also as a tape, card, microfiche, etc. that can be directly recorded and reproduced with laser light. The details of the present invention will be described below using examples, but the present invention is not limited to these examples. Example 1 Polymethyl methacrylate (Acrycon manufactured by Mitsubishi Rayon) was deposited on a glass disc-shaped substrate with a thickness of 1.2 mm, an outer diameter of 300 mm, and an inner diameter of 35 mm using a spinner.
A methyl ethyl ketone solution was applied and dried to form a polymethyl methacrylate layer with a thickness of 3 μm. The resulting substrate with the polymethyl methacrylate layer was heated to a wavelength of 450 nm or less using a condensing irradiation device equipped with a high-pressure mercury lamp with a lamp output of 80 W/cm.
The polymethyl methacrylate layer was irradiated with ultraviolet light having an energy of 120 mJ/cm ² by passing through an area of 30 mW/cm ² using a belt conveyor. The glass substrate having the polymethyl methacrylate layer irradiated with ultraviolet rays obtained as described above was attached to the chamber of a vacuum evaporation device, and each of the two crucibles of the evaporation device was filled with Sn (Furuuchi Chemical Co., Ltd.,
20φ×10mmt, purity 99.99%) and SnO ₂ (manufactured by Furuuchi Chemical, 18φ×5mmt, purity 99.99%), and while rotating the substrate at a speed of 20 rpm, the vacuum was 2×.
At 10 ^-6 mHg, Sn and SnO ₂ were irradiated with electron beams from separate electron guns, and vapor deposition was performed while controlling the evaporation rate of Sn and SnO ₂ onto the ultraviolet irradiated surface of the polymethyl methacrylate layer. An optical recording medium having the structure shown in FIG. 1 was manufactured, having a recording layer having a thickness of 270 Å and consisting of a composite layer in which Sn fine particles with a Sn filling factor of 0.8 were dispersed in SnO ₂ . While rotating the obtained disk-shaped optical recording medium at a speed of 1800 revolutions per minute, the frequency of
The oscillation light of a semiconductor laser (HLP-1600 manufactured by Hitachi, oscillation wavelength 830 nm) modulated to a pulse width of 100 nsec is focused and irradiated onto the recording layer to a beam diameter of 1 μm through the collimator lens, condensing lens, and substrate. When recording was carried out using this method, the laser beam intensity on the recording surface of the disk required to form pits with a minor axis of approximately 1 μm was 6 mW. In addition, the recorded signal was reproduced using the same semiconductor laser used for recording at a laser light intensity of 1 mW, and the CN ratio was measured with a spectrum analyzer under the conditions of a reference signal of 5 MHz and a band width of 30 KHz.
It was 52dB. Comparative Example 1 A glass disk-shaped substrate similar to that used in Example 1 was attached to the chamber of a vacuum evaporation device,
Using electron beam evaporation at a substrate rotation speed of 20 rpm and a vacuum level of 2 x 10 ^-6 mmHg, the same procedure as in Example 1 was carried out.
Sn and SnO ₂ were co-deposited on the surface of the glass substrate while adjusting the deposition rate, and Sn was deposited to a thickness of 260 Å.
A sample was fabricated in which a composite layer of Sn dispersed in SnO ₂ with a filling factor of 0.8 was formed on a glass substrate. The obtained disk-shaped sample was subjected to repeated 100 nm treatment at a frequency of 5 MHz in the same manner as in Example 1.
An attempt was made to record with a semiconductor laser beam modulated to a pulse width of sec, but it was not possible to form pits even at a laser beam intensity of 12 mW on the recording surface of the disk. As shown above, Sn fine particles are formed on the glass substrate.
It is clear that the sensitivity of the sample in which the composite layer dispersed in SnO ² was directly formed is significantly lower than that of the optical recording medium of the present invention. Comparative Example 2 A polymethyl methacrylate layer with a thickness of 3 μm was provided on a glass disc-shaped substrate similar to that used in Example 1 in the same manner as in Example 1, and a substrate with the obtained polymethyl methacrylate layer was obtained. was attached to the chamber of a vacuum evaporation device, and Sn and SnO ₂ were co-evaporated under the same conditions as in Example 1 to form a polymethyl methacrylate layer with a thickness of 270 Å and a Sn filling rate of 0.8.
A sample was fabricated in which a composite layer was formed in which fine Sn particles were dispersed in SnO ₂ . The obtained disk-shaped sample was repeatedly heated for 100 ns at a frequency of 5 MHz in the same manner as in Example 1.
When recording was performed with a semiconductor laser beam modulated to a pulse width of to the reference signal
The CN ratio measured with a spectrum analyzer under the conditions of 5 MHz and 30 KHz band width was 41 dB. As shown above, a sample obtained by directly forming a recording layer on a polymethyl methacrylate layer provided on a glass substrate without irradiating energy rays such as ultraviolet rays can be used in the optical recording medium of the present invention. In comparison, the recording sensitivity is low and the CN ratio is also low. Example 2 An organic polymer layer with a thickness of 3 μm shown in Table 1 was formed on a disk-shaped glass substrate similar to that used in Example 1 using the same method as in Example 1. The polymer layer was irradiated with ultraviolet rays having an energy of 120 mJ/cm ² using the same method as in Example 1. Using the same method as in Example 1, fine particles of the metals shown in Table 1 were dispersed in the metal oxides also shown in Table 1 on the organic polymer layer obtained as above and irradiated with ultraviolet rays. and metal filling rate 0.85, thickness
An optical recording medium with a 280 Å composite recording layer was fabricated. When recording and reproducing the obtained disc-shaped optical recording medium under the same conditions as in Example 1, the laser light intensity on the recording surface of the disc necessary to form pits with a short axis of approximately 1 μm, The CN ratio is shown in Table 1.

[Table] Example 3 Five disc-shaped sheets made of polymethyl methacrylate made by the casting method with a thickness of 1.2 mm, an outer diameter of 300 mm, and a diameter of 35 mm were prepared, and four of these disc-shaped sheets were heated to a high voltage with a lamp output of 80 W/cm. Light intensity at a wavelength of 450 nm or less using a condensing irradiation device with a mercury lamp
The polymethyl methacrylate sheet was irradiated with ultraviolet rays having the energies shown in Table 2 by passing through an area of 30 mW/cm ² at different speeds using a belt conveyor. The four polymethyl methacrylate sheets obtained as described above and irradiated with ultraviolet rays were attached to the chamber of a vacuum evaporation apparatus, and the ultraviolet irradiated surface of the polymethyl methacrylate sheet was An optical recording medium having the structure shown in FIG. 2 was fabricated, having a recording layer having a thickness of 300 Å and consisting of a composite layer in which Sn fine particles with a Sn filling factor of 0.85 were dispersed in SnO ₂ . When recording and reproducing was performed on the obtained disc-shaped optical recording medium under the same conditions as in Example 1, the laser light intensity on the recording surface of the disc required to form pits with a short axis of approximately 1 μm was determined. , CN ratio is shown in Table 2. For comparison, the recording and reproducing characteristics of a sample in which the recording layer was directly formed on the surface of the remaining polymethyl methacrylate sheet without UV irradiation are also shown in Table 2 as sample number 3-5. show.

[Table] Example 4 Nine polymethyl methacrylate sheets similar to those used in Example 3 were prepared, and these sheets were exposed to 90 mJ/cm ² using the same ultraviolet irradiation device as in Example 3. irradiated with ultraviolet rays of energy. Using the same method as in Example 1, fine particles of the metals or semiconductors shown in Table 3 were deposited on the ultraviolet irradiated surface of the polymethyl methacrylate sheet that had been irradiated with the ultraviolet rays obtained as described above. An optical recording medium having a recording layer consisting of a composite layer having metal or semiconductor filling ratios and film thicknesses shown in Table 3 was produced. When recording and reproducing the obtained disc-shaped optical recording medium under the same conditions as in Example 1, the laser light intensity on the recording surface of the disc necessary to form pits with a short axis of approximately 1 μm, Table 3 shows the CN ratio.

[Table] Example 5 A sheet of polymethyl methacrylate similar to that used in Example 3 was irradiated with ultraviolet rays with an energy of 90 mJ/cm ² using the same ultraviolet irradiation device as in Example 3. . The polymethyl methacrylate sheet obtained as above and irradiated with ultraviolet rays was heated to a diameter of 200 mm.
It was attached to the chamber of a sputtering device equipped with SnO ₂ and Sb targets (both made by Furuuchi Chemical, purity 99.9%), and while rotating the polymethyl methacrylate sheet, a 30 Å thick layer was first placed on the ultraviolet irradiated surface of the sheet. A thin Sb layer is formed, and then a 20 Å thick SnO ₂ layer is formed on this Sb layer. Repeat this operation 5 times, and finally
By forming a 30 Å thick Sb layer, 30
6 layers of Sb with a thickness of Å, and a layer of 20 Å sandwiched between the Sb layers
An optical recording medium having a recording layer with a stacked thickness of 280 Å consisting of 5 SnO ₂ layers with a thickness of 280 Å was fabricated. When recording and reproducing was performed on the obtained disc-shaped optical recording medium under the same conditions as in Example 1, the laser light intensity on the recording surface of the disc required to form pits with a short axis of approximately 1 μm was determined. 10mW,
The CN ratio was 48dB. Example 6 A sheet of polymethyl methacrylate similar to that used in Example 3 was irradiated with ultraviolet light having an energy of 90 mJ/cm ² using the same ultraviolet irradiation device as in Example 3. The polymethyl methacrylate sheet that had been exposed to the ultraviolet irradiation device obtained above was attached to the chamber of a vacuum evaporation device, and each of the three crucibles of the evaporation device was filled with Sn (manufactured by Furuuchi Chemical Co., Ltd., 20φ×10mm).
t, purity 99.99%), SnO ₂ (manufactured by Furuuchi Chemical, 18φ
×15mmt, purity 99.99%), Ge (manufactured by Furuuchi Chemical,
30φ×10mmt, purity 99.999%), and while rotating this sheet at a speed of 30 rpm,
Using electron beam evaporation method under the condition of 10 ⁶ mmHg,
Ge was first vapor-deposited to a thickness of 40 Å on the ultraviolet irradiated surface of the polymethyl methacrylate sheet, and then Sn
By irradiating electron beams on and SnO ₂ from separate electron guns and performing co-evaporation while controlling the evaporation rate of Sn and SnO ₂ , a film thickness of 180 mm was obtained with a Sn filling rate of 0.8.
A composite layer in which Sn fine particles of Å are dispersed in SnO ₂ is formed on the Ge layer, and finally a layer of 40 Å thick is formed on this composite layer again.
A disk-shaped optical recording medium having a recording layer with a thickness of 260 Å was fabricated by forming a Ge layer of 260 Å. When recording and reproducing was performed on the obtained disc-shaped optical recording medium under the same conditions as in Example 1, the laser beam intensity on the recording surface of the disc required to form pits with a short axis of approximately 1 μm was determined. teeth
A value of 6mW and CN ratio of 57dB was obtained. In addition, when the disc-shaped optical recording medium recorded in Examples 1 to 6 above was placed in a constant temperature and humidity layer at 60°C and 95% RH, and a 120-day moisture and heat resistance test was conducted, the CN ratio changed. was not recognized.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of the optical recording medium of the present invention. In each figure, 1 is a recording layer, 2 is an organic polymer layer, 3 is a substrate, and 4 is an energy beam irradiated surface of 2.

Claims (1)

[Claims] 1. Energy amount is 10 mj/cm ² or more and wavelength 190
Consisting of an organic polymer layer whose main chain has been partially cut by irradiation with ultraviolet light of 420 nm, and a recording layer made of a metal or semiconductor and a metal oxide provided on the organic polymer layer. optical recording media. 2. The organic polymer according to claim 1, wherein the organic polymer is at least one selected from polymethyl methacrylate, a copolymer containing methyl methacrylate as a main component, or polystyrene or a copolymer containing styrene as a main component. optical recording medium. 3 The metal or semiconductor is Sn, In, Sb, Pb, Al,
The optical recording medium according to claim 1, which is at least one selected from Zn, Cu, Ag, Au, and Ge. 4. The optical recording medium according to claim 1, wherein the metal oxide is at least one selected from oxides of Sn, In, Al, Zr, and Zn. 5. The optical recording medium according to claim 1, wherein the recording layer is a composite layer in which fine particles of metal or semiconductor are dispersed in a thin film of metal oxide.