JPS62205553A - Optical disk - Google Patents

Abstract

PURPOSE:To improve peeling resistance and reliability by providing a transparent contact layer consisting of fluororesin between a transparent resin substrate and a protective layer consisting of a transparent inorganic dielectric substrate and forming a recording layer on the protective layer. CONSTITUTION:As a translucent resin substrate 1, a polycarbonate substrate having a guide groove of phi 120mm and 1.2mmt is used and the transparent contact layer 2 consisting of the fluororesin (tetrafluoro ethylene) is formed on the substrate 1. Then, the first interference layer 3 composed of a Si3N4 film, the recording layer 4 composed of a TbCo film, the second interference layer 5 composed of the Si3N4 film and a light reflecting layer 6 composed of an Al film 6. Thus, the separation resistance is improved and the reliability of the optical disk can be improved.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an optical disk on which information is recorded and reproduced by irradiation with a light beam such as a laser beam. The present invention relates to the same technology as above for reliability of an optical disc having a protective interference layer consisting of a carrier and a recording layer formed with a VC thereon.

[Technical background of the invention and its problems]

An optical information recording medium, a so-called optical disk, records and extracts information by being irradiated with a light beam from a semiconductor laser, etc. (1) The recording area per bit is the spot diameter of the light beam (~1 μmφ). (2) Information is recorded and reproduced without contact, so there is no wear on the medium.

(3) It is highly anticipated as a next-generation peripheral memory because of its advantages such as high-speed access of several hundred msec or less.

Such optical discs basically consist of a disc-shaped substrate,
and a recording layer that undergoes some optical change upon irradiation with a light beam. Here, optical changes in the recording layer include: (a) The part irradiated with the light beam is deformed (formation of bits or bubbles), and the light reflectance of the deformed part changes.

(b) The light beam irradiation section undergoes phase change, and the light reflectance of the phase change section changes.

(c) The magnetization of the light beam irradiation section is reversed, and the polarization state of the magnetization reversal section is changed.

Examples of such phenomena include:

Optical disc Vζ that utilizes nine deviations of these optical changes
Even in this case, it is practical to irradiate the recording layer with a recording/reproducing light beam through the substrate.

This is because dirt and dust adhere to the 4-output side of the recording layer, so writing and reading errors will increase if the light beam is irradiated from the exposed side. However, if sufficient care is taken, dust can be prevented from adhering, and since the light beam is defocused on the surface of the substrate opposite to the recording layer, dust adhering to this surface is unlikely to cause errors. This is due to two reasons:

This is a method of irradiating the original beam through the substrate.
In case A, the substrate of the optical disk is naturally required to be translucent (transparent), and furthermore, in order to lower the noise level, it is required to be made of a material with as low a birefringence as possible. In addition, in order to quickly move the optical head to a predetermined position on the disk surface and achieve high-speed access, a group (guide groove) is required to guide the optical head.
It is far more advantageous from the standpoint of recording layer forming technology to provide this guide groove in advance over the width of the substrate than to provide it on the recording layer.

These three basic requirements (translucency, low birefringence).

The substrate materials that also satisfy the moldability of the guide groove are polymethyl methacrylate and polycarbonate.

It is a translucent ml resin material typified by epoxy and the like.

-10,000, The recording layer material can be a carbon-based material typified by spiropyran dye, a medium oxide-based material typified by Te-C, a metal-metal compound mixed system typified by TeOx, or a semi-drying material typified by In-5b. Although a wide variety of metal systems, including rare earth-transition gold and 4-amorphous ferrimagnetic alloys (hereinafter abbreviated as RE-TM), have been put into practical use or researched and developed, it is unlikely that they will be put to practical use as original memory. There are very few materials that have a sufficient memory life with a single recording layer, and in such cases a protective film is used. When using a glass substrate, it is sufficient to provide a protective film only on the surface of the recording layer that is exposed to the air. However, when using a practical resin substrate, the outside air passes through the substrate, so In such a case, the protective film must be transparent and dense, usually 5iOz, SiO, A#, 5i3N4s.
A spackle film made of a non-porous dielectric material such as ZnS is used. However, in most cases, the adhesion between the resin substrate and the protective layer made of non-electrical material is extremely poor, resulting in the problem of the protective layer peeling off from the substrate due to the temperature and humidity history of accelerated deterioration environmental tests. There was a point. For example, the %RE-TM film is currently being developed in various places as the most practical recording material for erasable optical discs, but the above-mentioned peeling problem is one of the obstacles preventing its practical use.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned technical background and problems, and includes fluorine 6°j (fat free) between the transparent negative side substrate and the transparent protective layer made of a non-staining material. The purpose of this is to improve the peeling resistance and reliability of the optical disc by providing an adhesive layer containing the compound.

[Summary of the invention]

The optical disc of the present invention comprises a transparent protective layer made of an inorganic dielectric material and a recording layer formed on the protective layer on a transparent resin substrate, and fluorine is provided between the resin substrate and the protective layer. It is characterized by being provided with a transparent adhesive layer containing resin.

The material of the recording layer is not particularly limited, but it is effective for metal-based materials that require a protective layer, especially for RE-TM films that are sensitive to oxidation. In addition, the transparent adhesive layer contains fluorine 11
11 (Those with C-F bond) In addition to those consisting of 100 chips, a mixture of fluororesin and inorganic dielectric material, or a mixture of fluororesin and inorganic dielectric material in the thickness direction of the adhesive layer. The mixture ratio may be changed, and its formation is as follows:
This can be achieved by sputtering a tetrafluoroethylene target, simultaneously sputtering a tetrafluoroethylene target and an inorganic dielectric target, or plasma polymerizing a Freon gas.

〔Effect of the invention〕

According to the optical disc of the present invention, the fluororesin adhesive layer allows the resin substrate to be made of polymethyl methacrylate, polycarbonate, epoxy, etc., which is practical as an optical disc;
Recording materials with particularly poor corrosion resistance (for example) because the adhesion with the transparent inorganic dielectric that protects the recording layer is significantly improved? E
- The reliability of optical discs using TM films can be greatly improved.

In addition, since the fluorine-fingered adhesion layer has a high transmittance, the optical properties of the original disk (for example, in the case of WE-7M film, the reflectance from the substrate side and the Kerr rotation angle) may be slightly lost. There isn't. Furthermore, the fluororesin adhesive layer can be formed using a dry fist process, so compared to spin cord methods, etc.
The shape of the tracking φ group provided on the substrate is rarely specified.

[Embodiments of the invention]

The present invention will now be described in detail. : FIG. 1 is a sectional view of an optical disc according to an embodiment of the present invention, in which a transparent adhesive layer 3 containing a fluorocarbon resin and a transparent adhesive layer 3 are formed on a transparent resin substrate 1. A recording In 4 is formed on the recording layer 4, and a second protective layer f1!5 and a light reflective layer 6 are roughly formed on the recording layer 4.
are formed in sequence.

It is assumed that a polycarbonate substrate, for example, is used as the transparent resin substrate 1, and a guide groove is formed on the surface thereof. Adhesion 1 and 2 contain, for example, tetrafluoroethylene as the fluorine compound. The recording layer 4 is made of, for example, a TbCo film (E-7M film). The protective layers 3 and 5 are made of, for example, a Si3N4 film, and the light reflecting layer 5 is made of an M film.

FIG. 2 shows an example of the configuration of a sputtering apparatus used for manufacturing this optical disk, in which 11 is a sputtering chamber, 12 is a substrate holder that holds the transparent resin substrate 1 shown in FIG. 1, and 13 is a rotation of the substrate holder 12. jig, 14 is an RF power supply, 15 is a sputtering source for magnetron sputtering, 16 is a first source for sputtering, 17 is a shutter, 18 is a shield member, 19 is a sputtering gas supply system, 20 is an exhaust system, 21 is a substrate installation It is a jig for use.

Hereinafter, specific embodiments of the optical disc manufacturing process according to the present invention will be described.

<Example 1> Using the sputtering apparatus shown in FIG. 2, an optical disk having the structure shown in Fig. N1 was manufactured in the following procedure. As the translucent resin substrate 1, a polycarbonate substrate with a guide groove of 12011 m in diameter and 1.2 ffllt was prepared. The sample was obtained by manufacturing a stubble from a master disk obtained by exposing and developing photoborea with an Ar ion laser, and using this stumbling block to injection mold polycarbonate. This substrate was subjected to ultrasonic cleaning for 5 minutes in a neutral detergent bath solution, washed with pure water, dried with N2 blow drying, and dried in a desiccator. I stopped it. The jig 21 is heated to 1J to seal the sputtering chamber 11, and the exhaust system 2o is operated to reduce the pressure inside the sputtering chamber 1 to 5 X I F5 Torr.
A with a purity of 99.999 from the gas supply system 19.
r gas is supplied, and the gas pressure in the sputtering chamber 11 is increased to 5
It was maintained at 10'' Torr. Next, the substrate holder] 2 is rotated at 6 Orpm using the jig 13, and with one of the shutters 17 closed, the sputtering source 15 (containing a 5-inch φ tetrafluoroethylene target) is placed under the VC4. An RF power of 150 W was applied from the power source 16. 5 minutes pre-sputter (shutter 17
After cleaning the target surface, the shutter 17 is fully opened as described above, sputtering is performed for about 20 minutes, the power source 16 is turned off, and the inside of the sputtering chamber is turned off to the atmosphere. After returning to
The substrate 1 on which was formed was taken out. At the same time, the substrate holder 12
Small pieces of glass, polymethyl methacrylate, polycarbonate, and epoxy installed in
As a result of evaluating the film quality of the adhesive layer 2 formed by the above method using m), the film thickness was 1oooX and the light transmittance was 931T.
(IjL length 830 nm, polymethyl methacrylate substrate), chemical resistance was good to the extent that no deterioration occurred even after ultrasonic cleaning during ascent for 30 minutes.

Adhesion to the substrate was strong enough that polymethyl methacrylate, polycarbonate, epoxy, and glass did not peel off from the substrate in a beer-off test using adhesive tape, and it was also rated at 65°C - 90SR.

Even after 4 cycles of 24Hrs in a high humidity atmosphere of Ho, 24Hrs in a normal temperature atmosphere, and 4 cycles of recycled accelerated deterioration tests, no peeling occurred from any of the above-mentioned 4 types of substrates, and Tetraflow There was no deterioration (change in light transmittance) of the loethylene film itself.

Next, targets of Si, 'rb, and CogAl are installed in the four sputtering sources 15 in FIG.
A recording layer 4 made of a film, a second interference layer 5 made of a Si3N4 film, and a light reflection layer F? made of an M film. A6 is formed by screwing the polycarbonate substrate on which the adhesive layer 2 is formed and the polycarbonate substrate on which the adhesive layer 2 is not formed for comparison to the equal plate holder 12, and lowering the jig 21 into the sputtering chamber. 11 inside the exhaust system 20V 5X10-6T
After exhausting with orr-4, a N2-Ar mixed gas with a partial pressure of N2 of 3% was introduced, and the gas pressure in the sputtering water 11 was increased to 5%.
Maintaining the temperature at X 1O-3 Torr, apply 300 WORF power from the 15Vc power supply 16 of the sputtering source for the Sl target, perform blur sputtering (target cleaning performed in the next state with the shutter closed) for 5 minutes, and then close the shutter. Open S by reactive sputtering
An i3N4 film was formed for 20 minutes, with a thickness of approximately 1000% on the adhesive layer 2 and the substrate l. A thick S13N4 film (first capture layer 3) was formed.

Next, the inside of the sputtering chamber 11 is again pumped through the exhaust system 20 by 5X
Exhaust to 10-'Torr and release gas from gas supply system 19 to 9
Ar gas with a purity of 9.999% is introduced into the sputtering chamber 11.
Using a trowel that maintained a gas pressure of 5XIO TorrK, the RF power supply 14 was turned on and the surface of the Si 3N4 film was heated at 300W (1
) Cleaned by sputter etching using RF power for 5 minutes.

Next, with the shutters 17 corresponding to the sputtering sources 15 for the Tb target and the Co target being closed, DC' power is supplied from the power source 16 to the sputter #15 of both targets, and 0.5 A is applied to the Tb target, and 0.5 A is applied to the Co target. <1.
The surface of each target was cleaned by press sputtering for 5 minutes using a discharge current of 5 A. Open at the same time and spread for 35 seconds F) TbCo
A recording layer 4 made of a TbCo film with a thickness of approximately 250 mm was formed, and the power source 16 was turned off.

Next, the gas is raised to N2-Ar mixed gas with a partial pressure of N2 of 3%, and the sputtering source 15 of the Sl target is heated at tS16 for 30 minutes.
0WI/) After applying RF power and performing press sputtering for 5 minutes, sputter film formation was performed for 5 minutes to form a second protective layer 5 made of a Si3N4 film with a thickness of about 250X on the recording layer 4.
was formed.

Next, the gas was changed to pure Ar gas, and 300 W of RF power was applied from the power source 16 to the sputtering source 15 of the AI METAT, and after 5 minutes of press sputtering, sputtering film formation was performed for 10 minutes.hSi3N4! A light reflection layer 1-6 made of an Al film with a thickness t) of about 100 OA is formed on the interference layer 5 made of
Turn off the direct image 16 and stop the rotation of the substrate 10,
The sputtering chamber 11 was returned to the atmosphere, the substrate 1 was raised by the holder 21, and the optical disk shown in Fig. 6FfJ1 was taken out.

On the other hand, glass, polymethyl methacrylate, polycarbonate, polymethyl methacrylate, polycarbonate,
Each piece of epoxy, and without the dense 11 layer installed for comparison. As a result of evaluating the performance immediately after film formation using a similar small piece, it was found that the light reflectance R and Kerr rotation angle θ measured by irradiating a laser beam from a He-Ne laser from the substrate surface side differed from that of a polymethyl methacrylate substrate. The sample with a 1° tetrafluoroethylene adhesive layer on top has R = 20%.
, θ = 0.45 deg%, and R = 25% for the sample without an adhesive layer.

θ = 0.45 deg, and it was confirmed that the structure V having the tetrafluoroethylene-dense PJ layer according to the present invention had a practically sufficient regeneration performance index (product of RXθ).

In addition, the results of the beer-off test using adhesive tape showed that samples with tetrafluoroethylene were closely immersed in glass and polymethyl methacrylate.

While no peeling occurred in either polycarbonate or epoxy, in the sample without m adhesion layer, all b:l except for the glass substrate peeled off. Also, this 11th
These small pieces and the original disk with the above-mentioned φ120fim polycarbonate board with guide 4 /11 were heated at 65°C.
To 90%, H, 24 Hrs, ←→ room temperature I Hr, -+
It was subjected to an accelerated deterioration test injection at 65°C and 90% R,i (48Iirs), and the presence or absence of peeling was investigated. Figure 3 shows the surface condition of one disc according to the present invention after this accelerated deterioration test. It is a microscopic photograph of a metal grommet dragon showing , (a) is a magnification of 10
(b) tr1 magnification of 1000 times. It is clear that no peeling is observed through the surface with the guide groove (striped portion) and the grooved surface. On the other hand, in conventional disks without an adhesive layer, a phenomenon was observed in which the film peeled off from the substrate due to accelerated deterioration.

<Example 2> In Example 1, tetrafluoroethylene was formed by adhesion #'& sputtering, but tetrafluorenathane 'I! fi appetizer 1=# can also be obtained by plasma polymerization of Freon gas. FIG. 3 is a diagram illustrating an example of the configuration of a plasma polymerization apparatus used for forming a deposited layer of tetrafluoroethylene. In FIG. 3, 41 is a polymerization chamber;
Reference numeral 42 denotes a substrate holder, which holds j#l]'iI substrate 1, for example, a polymethyl methacrylate substrate (φr2o, '@with inner groove). 43 is a coil.

44 is an RF a source, 45 is a gas supply system, and 46 is an exhaust system.

Using this plasma polymerization apparatus, a tetrafluoroethylene adhesive layer was formed through the following steps.

First, the polymerization chamber 41 is 5×10-6
After exhausting to Torr, CF4 is supplied from the gas supply system 45.
lj st10 secm, Ar gas is supplied at the same time as lO105c, RFvtm44t on rc, :=li
(Le 431C200Wr/) Supply RF power,
A CF4-Ar mixed gas plasma was excited in the polymerization chamber 41, and a plasma direct synthesis film was formed on the substrate 1 for 30 minutes, and then taken out. The film quality of this glazma-polymerized tetrafluoroethylene film was slightly inferior to that of the sputtered tetrafluoroethylene film in terms of chemical resistance, but was otherwise as good in vfi as the sputtered tetrafluoroethylene film. Further, on this plasma-polymerized tetra-70-loethylene film, a first protection layer made of Si3N4 film, a recording layer made of TbCo film, a second protection layer made of Si3N4 film, and When a light reflecting layer made of an Al film was sequentially formed and subjected to the υ11 speed deterioration test in the same manner as in Example 1, no peeling of the film occurred and no deterioration of the guide groove shape was observed.

<Example 3> In Example 1 and Example 2, a case was explained in which the adhesive layer was formed only from fluorine gel (tetrafluoroethylene), but the adhesive layer in the present invention was formed from fluorine navy blue. In addition to fat, it may contain an inorganic material having translucency. Examples thereof are shown below.

A polycarbonate substrate with a guide groove similar to that of Leprosy Example 1 was prepared as the translucent grout substrate 1, subjected to ultrasonic cleaning VC in a neutral detergent solution for 5 minutes, rinsed with supplementary water, then dried with N2 blow drying in a desiccator. After drying, the sputtering chamber 11
and screwed it to the substrate holder 12. Jig 21'
I'/JO is performed to seal the sputtering chamber 11, and the exhaust system 20 is operated 4+ to remove the IFtle in the sputtering chamber 11.
After the 5X10 'I'orrnf has passed, 3% N2-N2-Ar gas is supplied from the gas supply system 19 to increase the gas pressure in the sputtering chamber 11 to 5X10-3Torr.
IC! I went to Kaiji Temple.

Next, the substrate holder 12 is rotated at 60 rpm using the jig 13, and with the two shutters 170 closed, the sputtering source 15 (5 inch φ Tetra 70-
t50 W, 12
A power of 0W (D) was applied.Break sputtering was performed for 5 minutes (sputtering due to the mistake of closing the shutter 17).
After pre-cleaning the target surface, the two 7-layers 17 were fully opened, sputter film formation was performed for about 10 minutes, the power supply 16 was turned off, and the inside of the sputtering chamber 11 was returned to the atmosphere. Raise the jig 21 and add 75 vol of tetrafluoroethylene, % Si3N425 vo
The substrate 1 on which the adhesion I2 of 1.1% was formed was taken out. At the same time, the film quality of the bonding layer 2 was formed using the above method using small pieces of glass, polymethyl methacrylate, polycard, and epoxy (approximately 15 mm x 25 mm) placed on the substrate holder 12. As a result of evaluation, the film thickness was 1000X,
The light transmittance is 91% (wavelength 830 nm + polymethyl methacrylate substrate), the chemical resistance is good with no deterioration after 30 minutes of ultrasonic cleaning in acetone, and the adhesion to the substrate was determined by the beer off test using adhesive tape. Polymethyl methacrylate, polycarbonate, epoxy, and glass are strong enough to not peel off from the substrate, and can be used in a high-temperature, high-humidity atmosphere of roughly 65"C-90mm R, H, 24 hours.
Hrs, ← IHrcQ under room temperature atmosphere? Even after 4 cycles of the cycle accelerated deterioration test, it did not peel off from any of the four types of substrates mentioned above, and there was no deterioration (change in light transmittance) of the tetrafluoroethylene film itself. As described above, in the present invention, even when the adhesion layer is made of a mixture of H11 fat and an inorganic material, substantially the same effects as in the case of using fluororesin alone can be obtained.

Fruit turtle example 4> rM In accommodation example 3, tetrafluoroethylene and Si3N4
We have explained the case where the mixing ratio of tetrafluoroethylene in the adhesion layer consisting of a mixture of It has been found that the reliability of an adhesive layer made of such a mixture is improved by varying the mixing ratio of the fluorocarbon resin in the thickness direction of the adhesive layer. In this case, the way to change the fluoro-fat mixing ratio x is as follows:
In order to make the difference between adhesion, ■, thermal expansion coefficient and water absorption expansion coefficient between the substrate and the recording layer as close as possible, the average value of × in the thickness direction is ×, and on the side closer to the substrate
, it is appropriate that X<X on the side closer to the recording layer.

Figure 4 shows how the adhesion layer is formed by changing the mixture ratio of fluorine and fat in the thickness direction. This is a method of changing.

The adhesion layer having a change in mixing ratio as shown in FIGS. 4(a) and 4(b) can be formed by sputtering, for example, as shown in FIG. 2.

It can be formed by temporally changing the input power ratio to the tetrafluoroethylene target and the SL metal in the programming apparatus. On top of these adhesive layers, a first barrier made of 513N4 film was applied as in Example 1.
A recording layer made of TbCo film, a second layer made of Si3N4
A base disk with Q layers of light reflecting layers made of protection layer Al film was manufactured, and a mixture of tetrafluoroethylene and Si3N4 with a uniform mixing ratio of 75 vo 10% of tetrafluoroethylene as explained in Example 3 was manufactured. 80°C-90SR, H, 24H with an optical disc having an adhesive layer made of a mixture.
rs, (--) Room temperature IHr, 4 cycles → 80°C-
It was subjected to an accelerated deterioration test of 90SR-H, 96Hrs, which was more severe than that of Example 3.

The optical disk having an adhesive layer with a uniform tetrafluoroethylene mixing ratio was prepared using the 65゛C-90CHR,
In the cycle accelerated deterioration test under H, no peeling was observed on the entire surface of the disk, but under 8
It was found that a longer cycle accelerated deterioration test at 0°C-90SR,H caused local streak-like peeling. A similar phenomenon was also observed in the optical disk described in Example 1 in which an adhesive layer made of tetrafluoroethylene alone was formed.

On the other hand, in optical discs that have an adhesive layer with a step-like mixture ratio change, peeling occurs only on a small part of the surface without guide grooves, and the adhesive layer has a gradient-like mixture ratio change. It was found that no peeling occurred at all in the optical disc having the following. Therefore, in an environment such as an office, sufficient reliability can be expected even with an adhesive layer with a uniform mixing ratio, but when storing an optical disc for a long time in a harsher environment, it is necessary to Higher reliability can be obtained with the adhesion layer in which the mixing ratio of Fluorine 1 and V) is changed.

In addition, when forming an adhesion layer having a step-like mixture ratio change as shown in FIG. 4(a) IIC and including a layer of 100% tetrafluoroethylene,
100% tetrafluoroethylene layer V is CF
Formation is also possible by the Glazma Liao method using 4 gases. A layer of a mixture of tetrafluoroethylene and an inorganic material can also be formed by simultaneous plasma polymerization of CF4 gas and sputtering of an inorganic material target, but since the manufacturing conditions are difficult, it is possible to form a layer of a mixture of tetrafluoroethylene and an inorganic material. - Simultaneous sputtering of a target and an inorganic material target is preferable.

Broadly speaking, the present invention can take various embodiments as described below. For example, in the above embodiments, a ThCo film that utilizes the magneto-optical effect was used as the recording layer, but other Rw
-TM film, or an optical disk having an outer recording layer outside the RE-TM film, such as a CuAl film that uses a shape memory effect, or a 5eTe K film that uses a change in crystal structure.
The adhesion layer according to the present invention can also be applied to an optical disk having a recording layer made of an InSb film or the like, and the same effects as in the previous Jinoike example can be expected.

In addition, in Example 3, Si3N4 was shown as a translucent inorganic material to be mixed with fluorocarbon resin (tetrafluoroethylene), but inorganic materials other than Si3N4, such as SiO2,
SiO, A717N, ZnS, CaF2. A similar effect can be obtained by using ITO or the like. In fact, using targets made of these inorganic materials, sputtering was performed at the same time as a tetrafluoroethylene Φ target, and an adhesive layer made of a mixture of these materials was deposited on a four-layer substrate of polymethyl methacrylate, polycarbonate, epoxy, and glass. When formed and subjected to a beer-off test, the adhesion layer with a uniform mixing ratio in the thickness direction had a tetrafluoroethylene mixing ratio of 50 vol.

No peeling occurred from any of the substrates, and no peeling was observed at all in the adhesive layer where the mixture ratio varied in a gradient manner.

In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[Brief explanation of drawings]

FIG. 1 shows an optical information recording medium (
FIG. 2 is a block diagram of a sputtering device as an example of the device used for manufacturing the optical disk of the present invention, and FIG. 3 is a cross-sectional view of another device used for manufacturing the original disk of the present invention. A block diagram of a plasma polymerization apparatus as an example, FIG. It is a figure which shows the example of a change of a mixing ratio. 1... Transparent ml fat substrate 2... Adhesive layer 3... First protective layer 4... Recording layer 5... Second protective layer 6... Light reflection 1j Agent Patent attorney Shi Nori Kinsho Yudo Takehana Kikuo 1st figure false 2 figure 3f! iii Inkstone layer Figure 4

Claims (2)

[Claims] (1) In an optical disc comprising a protective layer made of a transparent inorganic dielectric material on a transparent resin substrate and a recording layer formed on the protective layer, fluorine is added between the transparent resin substrate and the protective layer. An optical disc characterized by being provided with a transparent adhesive layer made of resin. (2) Claim 1, wherein the recording layer is made of a rare earth-transition metal amorphous ferrimagnetic alloy thin film.
Optical disc described in section.