JPH0327034B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an optical information recording medium and a manufacturing method thereof. Conventional technologies and problems Optical information recording media have attracted attention because their recording density is one to two orders of magnitude higher than that of conventional magnetic recording media. is being studied. Manufacturing methods for optical information recording media include PVD sputter deposition, vacuum deposition,
A method of forming a thin film by ion beam evaporation, etc.
Research has been conducted into methods of forming thin films using the CVD method, and currently research is centered on manufacturing using the PVD method, and some of these have been put into practical use. In this PVD method, it is necessary to form a thin film under vacuum, which makes continuous production of recording media impossible, and it is necessary to precisely control vacuum conditions in order to form a good thin film. There is a problem. Furthermore, the PVD method has a problem in that even if magnetic field control and ion control are performed, the yield of forming a vapor-deposited film of raw material elements is very low. On the other hand, JP-A-50-46318 describes the use of a thin film containing tellurium oxide and vanadium oxide for an optical recording member. However, as described in the above-mentioned publication, this film is produced using a vacuum evaporation method, so decomposition occurs, and although it is superior to non-oxide glass materials, it still does not have a sufficient contrast ratio. I can't get it. For this reason, despite progress in research into the fundamental mechanisms of optical information recording systems, such as recording methods, playback methods, erasing methods, etc., there are still problems with recording media and their manufacturing methods in terms of media materials, costs, etc. Problem not resolved. Means for Solving the Problems The inventor of the present invention has conducted various studies in view of the above-mentioned points, and has found that the general formula (V ₂ O ₅ ) _1- x (MmOn) x (where MmOn is Li ₂ O, MgO, TiO ₂ , Ta ₂ O ₃ ,
_Cr2O3 , _MoO3 , _MnO2 , _{Co2O3 , NiO} , ZnO,
Indicates one or more oxides selected from B ₂ O ₃ , SiO ₂ , GeO ₂ , Bi ₂ O ₃ , and Fe ₂ O ₃ . However, O≦X≦0.85
It is. ) has a very large solubility compared to crystalline substances,
By coating a solution of the amorphous substance on a substrate and removing the solvent, an amorphous thin film can be easily obtained, and the thin film is significantly more stable and less likely to decompose than those obtained by vacuum evaporation, sputtering, etc. It was found that the film did not cause any oxidation and had a high transmittance. The present invention is based on this knowledge. That is, the present invention provides the general formula (V ₂ O ₅ ) _1- x
(MmOn) x (In the formula, MmOn and The present invention relates to a method for manufacturing an optical information recording medium, and an optical information recording medium comprising an amorphous thin film having a composition represented by (wherein MmOn and X are the same as above) formed by coating on a substrate. The amorphous substance used in the present invention is
Shown as V ₂ O ₅ alone or V ₂ O ₅ and MmOn
Li ₂ O, MgO, TiO ₂ , Ta ₂ O ₃ , Cr ₂ O ₃ , MoO ₃ ,
MnO ₂ , Co ₂ O ₃ , NiO, ZnO, B ₂ O ₃ , SiO ₂ ,
It consists of one or more oxides selected from GeO ₂ , Bi ₂ O ₃ , and Fe ₂ O ₃ . In the latter case, the content of MmOn is
Appropriately, it is about 85 mol% or less, preferably about 70 mol% or less, and if the V ₂ O ₅ content is too low, a good amorphous film cannot be formed on the substrate. In the latter case, the oxide represented by MmOn to be used is appropriately selected depending on the purpose, and can be effectively used singly or in combination of two or more. In the present invention, by using the above metal oxide together with V ₂ O ₅ , it is possible to increase the optical sensitivity, increase the thermal absorption effect, facilitate the conversion to a crystal stable phase, and improve the amorphous amorphous phase. It has effects such as stabilizing the state, affecting the interfacial tension in the molten state, increasing optical reflectance, increasing optical absorption, and changing optical transmittance. An appropriate oxide can be used depending on the purpose. Specifically, for example, oxides of Bi, Ti, Ge, Cr, and Fe improve optical sensitivity, and oxides of Cr, Mo, Fe, Co, Ti,
Oxides of Ni and Bi provide optical effects, and oxides of Bi and Zn have effects such as phase conversion at low energy. The method for obtaining such an amorphous material may be any known method, and a method in which the melt of the target material is sprayed onto the surface of a high-speed rotating roll and ultra-quenched to form an amorphous material is advantageous in terms of production cost. Specific examples of methods for producing amorphous substances include Japanese Patent Application No. 55-152562, Japanese Patent Application No. 55-160193,
Patent application 1982-142197, Patent application 1982-211444, Patent application 1982
-220916, patent application 1982-210434, patent application 1982-
212061, Japanese Patent Application 1986-64273, Japanese Patent Application 1987-67463, Japanese Patent Application 1986-65083, Japanese Patent Application 1987-65003, Japanese Patent Application 1987-
66685, Japanese Patent Application 1986-67462, Japanese Patent Application 1986-69640, Japanese Patent Application 1987-69641, Japanese Patent Application 1986-66684, Japanese Patent Application 1986-
65004, Japanese Patent Application No. 58-68962, Japanese Patent Application No. 169208-1982, Japanese Patent Application No. 79736-1982, Japanese Patent Application No. 79739-1987, and the like. An example of a method for amorphizing a composition made of a metal oxide represented by V ₂ O ₅ and MmOn will be specifically explained below. First, V ₂ O ₅ as raw material
and MmOn are mixed and calcined at a temperature near the melting point to obtain the composition (V ₂ O ₅ ) _1- x (MmOn) x. Next, this composition is filled into a crucible, heated and melted in the atmosphere at a temperature 50 to 200°C higher than the melting point, and the melt is blown onto a high-speed rotating roll using compressed air.
A ribbon-like amorphous material is obtained by ultra-rapid cooling at a cooling rate of 10 ⁴ to ^{10 7} °C/sec. In the present invention, the obtained amorphous material is then coarsely ground and dissolved in water or an aqueous solvent.
At this time, the solubility of the amorphous substance is much higher than that of the crystalline substance, so a highly concentrated solution can be obtained. The aqueous solvent used in the present invention refers to water to which a water-soluble solvent or water-soluble polymer is added to control evaporation and adjust viscosity. and determine its use as appropriate. Typical examples of water-soluble solvents include:
CH ₃ OH, C ₂ H ₅ OH, C ₃ H ₇ OH, n-C ₄ H ₉ OH,
Examples include alcohols such as iso-C ₄ H ₉ OH, ketones such as (CH ₃ ) ₂ CO, polar solvents such as DMF and DMSO, and glycols such as ethylene glycol and propylene glycol. Examples of water-soluble polymers include polyvinyl alcohol, polyacrylamide, polyacrylic acid, and the like. Next, a solution in which the amorphous substance is dissolved is applied to the optical information recording substrate. This substrate is usually made of glass, synthetic resin, metal, or the like, and has a thin film with high optical absorption or a thin film with high optical reflectance formed thereon. After applying the amorphous substance solution, these substrates are heat-treated at 50 to 300°C in air or vacuum to completely remove moisture, thereby obtaining an amorphous thin film layer. The thin film thus obtained is a thin film of uniform thickness and excellent durability. An optical information recording material can be obtained by laminating a glass or synthetic resin plate with good optical transparency and a low refractive index on this amorphous thin film. A cross-sectional view of an example of such a recording material is shown in FIG.
In the figure, 1 is a substrate, 2 is an optical reflection layer or an optical absorption layer, 3 is an amorphous layer, and 4 is a transparent protective layer. Furthermore, by using a metal tape, synthetic resin tape, etc. as the substrate, an optical information tape can be obtained in a similar manner. For recording on the optical information recording medium of the present invention,
As a light source for reproduction and erasing, He−Ne, He−
Cd, Ar, Kr, _CO2 , _N2 , HF-DF, _CD3OH-
Gas lasers such as 13CH ₃ F, CO, KrF-XeF,
Solid-state lasers such as YAG and ruby glass, GaA
Semiconductor lasers such as As, InGaAsP, PbSnTe-PbSSe, and CdSeInSb can be used, and light sources such as mercury lamps, xenon lamps, and tungsten lamps can also be used. The recording method of the recording material of the present invention is to use a combination of an amorphous material, that is, V ₂ O ₅ , and a metal oxide to dig pits or form grooves in the recording layer by irradiation with an energy beam of optical heating. Alternatively, a method of causing a phase transition between an amorphous phase and a crystalline phase in the recording layer using an energy beam is possible, and in the case of the latter method, erasing after recording is also possible. Examples of recording media that can be used in the recording pit forming method obtained in the present invention include V ₂ O ₅ , V ₂ O ₅ −
SiO ₂ , V ₂ O ₅ −GeO ₂ , V ₂ O ₅ −Li ₂ O, V ₂ O ₅ −
B ₂ O ₃ , V ₂ O ₅ −Fe ₂ O ₃ , etc., and examples of recording media that can be used in the phase change method include V ₂ O ₅ −
MgO, V ₂ O ₅ −ZnO, V ₂ O ₅ −Cr ₂ O ₃ , V ₂ O ₅ −
NiO, V ₂ O ₅ −Co ₂ O ₃ , V ₂ O ₅ −Bi ₂ O ₃ , V ₂ O ₅ −
Examples include _TiO2 . Effects of the Invention According to the method of the present invention, it is possible to easily and inexpensively form an optical recording medium of any thickness and excellent durability, regardless of the type of substrate. Since the recording medium of the present invention is an oxide, its thermal conductivity and expansion coefficient are very small, so by writing information with a low-energy laser, it is possible to form sharp pits or sharp phase boundaries. . Furthermore, the recording capacity per single area is approximately 120 to 200% higher than that of the PVD system currently on the market, and the S/N ratio is also increased. In addition, the electrical conductivity of the coating film of the present invention is 0.1 to 1.0 (Ω cm) ^-1 , which is a very good value.
It also has the effect of preventing static electricity on the disk itself, improving durability and reducing noise. Examples Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 15 With a two-component composition using V ₂ O ₅ (purity 99.9%) as a matrix, by ultra-quenching method using high-speed rotating rolls,
An amorphous ribbon material was obtained. The composition and manufacturing conditions are shown in Table 1. The obtained amorphous material has a particle size of 30 to 40 μm,
It was ground to a thickness of 5 to 10 μm, 300 mg was added to 10 cc of pure water, and after shaking for 30 minutes, it was left standing at room temperature for 3 days to dissolve. Undissolved amorphous substances were separated from this solution by filtration, and the liquid was applied to an optical information recording material substrate. After drying this at 50℃ for 30 minutes, 50-300℃
The adsorbed water was completely removed in the air at a temperature of 2.times.10.sup. ^-2 Torr or in a vacuum of about 2.times.10.sup.-2 Torr, and a recording medium layer was provided on the substrate. The structure of the recording medium layer formed on this substrate was analyzed by X-ray diffraction, and it was found to have an amorphous structure. In addition, the film thickness and formation state were observed using a scanning electron microscope.
It had a thickness of 5 μm and a smooth surface. An example of an X-ray diffraction diagram is shown in FIG. Regarding these materials,
The recording performance was measured using an optical writing device using a He--Ne laser beam. Table 2 shows the recording medium layer forming conditions and the laser recordability test results. Furthermore, Table 3 shows the results of measuring changes in recording pattern width due to changes in releaser output value. Microscopic photographs of the surface condition of the recording medium on which writing was performed are shown in reference figures. The reference drawing has _a composition of (V ₂ O _{5 ) 0.75}・(Li _{2 O} ) _{0.25 and was} recorded using the pit formation method. Based on the formation method, the reference drawing is (V ₂ O ₅ −) _0.67・
The reference drawing is an electron micrograph of one with a composition of (V ₂ O ₅ ) _0.70・(Cr _{2 O 3} ) _0.30 and a phase transition method. This is an optical micrograph of a pit pattern with a composition of V ₂ O ₅ ) _0.5 ·(GeO ₂ ) _0.5 written at 1 KHz using a pulsed laser. Comparative Example 1 A substrate was coated with an aqueous solution of a crystalline structure substance having the same composition as in Examples 1 to 15, and after drying, the surface was observed. As a result, the surface state was not smooth, and air bubbles, hair cracks, and fine crystal particles were mixed, and a thin film that could be used as an optical information recording medium could not be obtained.

【table】

【table】

【table】

【table】

[Table] * Items that can be recorded are indicated by a circle.

[Table] Comparative Example 2 A thin film recording medium containing tellurium oxide and vanadium oxide was produced by a vacuum evaporation method according to the example of JP-A-50-46318. The performance of this recording medium and the recording media obtained in Examples 3, 6, 11, and 13 was compared by measuring optical recording characteristics. The measurements were performed using a 488 nm argon gas laser capable of high-density recording. The results are shown in Table 4 as a contrast ratio based on the ratio of transmittance before and after recording. As a result, it can be seen that the product of the present invention has a low optical density before recording even at short wavelengths, so that a large contrast can be obtained.

[Table] Reference example 1 (V ₂ O ₅ ) x (MmOn) _1- Amorphous substances and crystalline substances represented by
It was ground to a thickness of 5 to 10 μm, 300 mg was added to 10 cc of pure water, and after shaking for 30 minutes, it was left standing at room temperature for 3 days to dissolve. Figure 3 shows the results of analyzing the amount of vanadium in the solution by atomic absorption spectrometry. The horizontal axis of the graph is the value of x for the substance represented by the general formula (V ₂ O ₅ ) x (MmOn) _1- x, and the symbols in the graph are the chemical formula of the metal element represented by M, and the solid line Circles indicate amorphous substances, and circles with broken lines indicate crystalline substances. Further, in the case of x=0.75, the change in the amount of dissolved V ₂ O ₅ over time was measured using a method similar to the method described above, and the results are shown in FIG. The symbols in the figure have the same meanings as those described above. It is clear from FIGS. 3 and 4 that amorphous substances have high solubility. Reference example 2 (V ₂ O ₅ ) x・(MgO) _1- x and (V ₂ O ₅ ) x・
(ZnO) The results of measuring the change over time in the amount of dissolution of the substance represented by _1- x in the same manner as in Reference Example 1 are shown in Figures 5 to 8. In the figure, ○ indicates the amount dissolved after 0.5 hours, △ indicates the amount dissolved after 1 hour, □ indicates the amount dissolved after 3 hours, and ◇ indicates the amount dissolved after 24 hours.
The solid line shows the amount of dissolved amorphous material, and the broken line shows the amount of dissolved crystalline material. The horizontal axis of the graph is the value of x, and the vertical axis is the amount of dissolved V ₂ O ₅ , MgO, or ZnO. In addition, Figure 9 shows the solution of (V ₂ O ₅ ) x (MgO) _1- x whose dissolved amount was measured by the method described above.
This is a graph recording changes in PH value. The horizontal axis of the graph shows the value of x, ○ means after 0.5 hours, △ means 1
After time, □ indicates the PH value after 3 hours, ◇ indicates the PH value after 24 hours, the solid line is the PH value of the amorphous substance, and the broken line is the PH value of the crystalline substance. From FIG. 9, it can be seen that the pH value of the amorphous substance solution shows little change and is stable for a long time. Reference Example 3 X-ray diffraction diagram of a thin film formed by the method of the present invention using a water-soluble colloid of an amorphous substance with (V ₂ O ₅ ) _0.83・(MgO) _0.17 after drying at room temperature and 30
The X-ray diffraction diagram after the thermal treatment is shown in FIG. In the figure, 9 is the X-ray diffraction diagram after drying at room temperature, and 10 is the 450
It is an X-ray diffraction diagram after heat treatment at ℃ for 30 minutes. From FIG. 10, it can be seen that a thin film made of an amorphous material with (V ₂ O ₅ ) _0.83 and (MgO) _0.17 is crystallized by heat treatment. Further, FIG. 11 shows the results of differential thermal analysis and thermogravimetric analysis of a thin film formed from an amorphous material of (V ₂ O ₅ ) _0.70 ·(Cr ₂ O ₃ ) _0.30 . In the figure, 11 is the result of differential thermal analysis, and 12 is the result of thermogravimetric analysis. The heat generation of 326°C in the differential thermal analysis is thought to be due to crystallization. From Figures 10 and 11 (V ₂ O ₅ ) _0.83・
It is clear that a thin film made of an amorphous material with (MgO) _0.17 and a thin film made of an amorphous material with (V ₂ O ₅ ) _0.70 /(Cr ₂ O ₃ ) _0.30 undergo a phase transition when heated, and this property can be used to create a laser beam. It can be seen that information can be written using the following methods.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of an optical information recording material. FIG. 2 is an X-ray diffraction diagram of the recording medium produced in the example. FIG. 3 is a graph showing the relationship between composition and amount of V ₂ O ₅ dissolved. FIG. 4 is a graph showing the change over time in the amount of V ₂ O ₅ dissolved. Figure 5 is a graph showing the relationship over time between the composition of a substance represented by (V ₂ O ₅ ) x (MgO) _1- x and the amount of dissolved V ₂ O ₅ , and Figure 6 is a graph showing ( V ₂ O ₅ ) x・
(MgO) _1- is a graph showing the relationship between the composition of x and the amount of dissolved MgO over time, and Figure 7 is (V ₂ O ₅ ).
x・(ZnO) _{1- This} is a graph showing the relationship over time between the composition of x and the amount of dissolved _{V 2} O _{5 ,} and FIG.
2 is a graph showing the relationship between the composition of x·(ZnO) ₁₋ x and the amount of dissolved ZnO over time. FIG. 9 is a graph showing the relationship between the composition of (V ₂ O ₅ ) x (MgO) _1- x and PH over time. Figure 10 is (V ₂ O ₅ )
It is an X-ray diffraction diagram of an amorphous material of _0.83 ·(MgO) _0.17 . FIG. 11 is a graph showing the results of differential thermal analysis and thermogravimetric analysis of an amorphous material with (V ₂ O ₅ ) _0.70 ·(Cr ₂ O ₃ ) _0.30 . In addition, in the figure, 1 is a substrate, 2 is an optical reflection layer or an optical absorption layer, 3 is an amorphous layer, and 4
is a transparent protective layer. Also, 5 is (V ₂ O ₅ ) _0.75・
(ZnO) _0.25 , 6 is (V ₂ O ₅ ) _0.67・(MgO) _0.33 , 7 is (V ₂ O ₅ ) _0.50・(Li ₂ O) _0.50 , 8 is (V ₂ O ₅ ) _0.70・
(Cr ₂ O ₃ ) It is an X-ray diffraction diagram of a recording medium having a composition of _0.30 . 9 is the X-ray diffraction diagram of the (V ₂ O ₅ ) _0.83 (MgO) _0.17 amorphous thin film after drying at room temperature, and 10 is the (V ₂ O ₅ ) _0.83 (MgO) _0.17 amorphous thin film at 450°C.
It is an X-ray diffraction diagram after heat treatment for 30 minutes. 11 is the differential thermal analysis result of an amorphous thin film of (V ₂ O ₅ ) _0.70・(Cr ₂ O ₃ ) _0.30 , and 12 is the result of (V ₂ O ₅ ) _0.70・
(Cr ₂ O ₃ ) _0.30 amorphous amorphous thin film thermogravimetric analysis results.

Claims (1)

[Claims] 1 General formula (V ₂ O ₅ ) _1- x·(MmOn) x (wherein MmOn is Li ₂ O, MgO, TiO ₂ , Ta ₂ O ₃ ,
_Cr2O3 , _MoO3 , _MnO2 , _{Co2O3 , NiO} , ZnO,
Indicates one or more oxides selected from B ₂ O ₃ , SiO ₂ , GeO ₂ , Bi ₂ O ₃ , and Fe ₂ O ₃ . However, O≦X≦0.85
It is. 1. A method for producing an optical information recording medium, which comprises dissolving an amorphous substance having the composition shown in () in water or an aqueous solvent, coating the solution on a substrate, and then drying the solution. 2. The optical system according to claim 1, wherein the amorphous substance is obtained by ultra-quenching its melt, vapor, or charged vapor in the atmosphere, vacuum, or inert gas. A method for manufacturing an information recording medium. 3 General formula (V ₂ O ₅ ) _1- x・(MmOn)x formed by coating on the substrate (where MmOn is Li ₂ O, MgO, TiO ₂ , Ta ₂ O ₃ ,
_Cr2O3 , _MoO3 , _MnO2 , _{Co2O3 , NiO} , ZnO,
Indicates one or more oxides selected from B ₂ O ₃ , SiO ₂ , GeO ₂ , Bi ₂ O ₃ , and Fe ₂ O ₃ . However, O≦X≦0.85
It is. ) An optical information recording medium comprising an amorphous thin film having a composition shown in 4. The optical information recording medium according to claim 3, which is formed on a metal thin film with high optical reflectance or a blackbody thin film with high optical absorption. 5. The optical information recording medium according to claim 3, wherein the substrate material is glass, metal, or synthetic resin.