JP2507881Y2 - Optical recording disc - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is directed to a document file represented by a magneto-optical recording medium for recording and reproducing information by using a laser beam,
The present invention relates to an optical recording disk suitable for use in image files, computer memory, sound recording, and the like.

<Problems to be Solved by Conventional Techniques and Inventions> As one of optical recording media, a medium for a magneto-optical memory is known.As a recording layer of the medium for a magneto-optical memory, for example, GdFe, Rare earth such as TbFe, TdFeCo, GdFeCo-
An amorphous magnetic thin film layer of a transition metal or the like is used. These thin film layers are usually formed on a transparent disc-shaped substrate by using a method such as a vacuum deposition method or a sputtering method, and are configured as an optical recording disc.

In this case, recording and reproduction are carried out from the back side of the substrate, but in the case of a single-sided recording type optical recording disk, it is disclosed in JP-A-60
-121549 and JP-A-61-21113 disclose that a polymer layer is formed on the surface of a recording layer provided on one side of a substrate, or on both sides of this recording layer and the substrate (in the figure, the entire surface of the disc is formed. It is disclosed that a moisture-proof polymer layer is formed. However, when the polymer layer is provided only on the recording layer, the moisture-proof effect is not sufficient as a matter of course. On the other hand, when the polymer layer is formed on the entire surface of the disc, the moisture-proof effect is improved. When forming the, when using the spin coating method, it takes a lot of time and labor to work, or a special spin coating machine must be used, and when using the dip method, the surface becomes rough, The recording / reproducing characteristics are deteriorated, and the accuracy of the outer diameter is not improved as expected, which causes a problem in the drive.

On the other hand, in the case of an optical recording disk of double-sided recording type, a pair of substrates each having a recording layer as shown in JP-A-58-108044 and JP-A-61-217944, for example. Are adhered to each other such that their recording layers are sealed.

However, in a magneto-optical recording disk using a rare earth-transition metal amorphous thin film as a recording layer, when the magnetic thin film layer is stored in a state of being in contact with the atmosphere, it may be affected by oxygen and moisture in the atmosphere. , Rare earths selectively corrode or oxidize.

This corrosion phenomenon occurs due to the invasion of the atmosphere from the bonding portion between the substrate and the recording layer, particularly the outer peripheral side thereof, but when this phenomenon occurs, it becomes impossible to record or reproduce the information.
It is a big problem in practical use. Problems like this
It occurs in a magneto-optical disk having a recording layer composed of another composition layer and also in an optical recording disk having a so-called phase transition type recording layer.

Therefore, a proposal has been made to solve this problem. For example, in the technique disclosed in Japanese Patent Laid-Open No. 63-837, the recording layers formed on a pair of substrates are brought into close contact with each other, and then only the peripheral portions of both substrates are joined with a high-viscosity adhesive, Proposals have been made to prevent atmospheric invasion by fixing.

However, in this method, as shown in FIG. 1 and FIG. 2 of the publication, a thick adhesive layer is formed on the outer peripheral side surface of the disk, and as a result, the accuracy of the external dimensions is poor. The drawback is that it tends to become a problem and interferes with the drive of the disk.

Further, this method can naturally be used only for an optical recording disc of a type in which two discs are bonded together.

<Problems to be Solved by the Invention> An object of the present invention is to eliminate this drawback and provide an optical recording disk having excellent corrosion resistance and weather resistance, and having a high bonding strength between the coating layer and the substrate. To do.

Another object of the present invention is to provide a highly accurate optical recording disk having a dimensional accuracy of the outer diameter of the disk.

<Means for Solving the Problems> Such an object is achieved by the present invention of the following (1) to (3).

(1) The outer peripheral surface of the disk-shaped substrate having a circular hole in the center is in contact with the annular layered body including the recording layer, and the outer diameter of the layered body forming surface is outside the surface not in contact with this layered body. The layered body is formed on a side surface of a truncated cone smaller than the diameter, and the layered body is arranged on the substrate in a state where annular inner and outer layered body non-arranged portions are left on the inner peripheral portion and the outer peripheral portion. Along with that, an annular recording area is provided in the central portion in the radial direction, and the inner peripheral portion and the outer peripheral portion thereof are non-recording areas, and the layered body is from an inner peripheral layered body non-arranged portion of the substrate,
An optical recording disk which is covered with a waterproof coating layer extending along the layered structure and extending to the side surface of the truncated cone, and the coating layer further covers the entire side surface of the truncated cone.

(2) The optical recording disk according to (1), wherein the entire coating layer is disposed inside the outer diameter of the surface that does not contact the layered body.

(3) An optical recording disc in which the two optical recording discs of (1) or (2) above are adhered to each other in such a manner that the respective layered bodies are contained therein.

Further, the waterproof coating layer is preferably a radiation-curable compound that is cured by, for example, ultraviolet rays or electron beams.

<Operation / Effect> The operation of the present invention is such that the outer peripheral surface of the substrate is a truncated cone side surface, that is, the joint length with the coating layer is made large by inclining, so that moisture in the atmosphere can be absorbed by the recording layer. It is to prevent the layered body including, especially the end surface thereof from reaching the layered body, and to increase the bonding strength.

Further, the corrosion resistance of the recording area is further improved by providing the inner and outer peripheral annular non-recording areas of the annular recording layer and the annular layered body non-arranging portions on the inner and outer circumferences of the substrate, respectively.

Further, the optical recording disk having the above-mentioned structure may be a double-sided recording type optical recording disk by closely bonding with an adhesive in a form in which the respective recording layers are included.

Furthermore, by making the outer peripheral surface of the substrate a truncated cone side surface, the protective layer provided on this truncated cone side surface can be arranged only inside the larger outer diameter of the substrate. Determined by the diameter (larger diameter), the dimensional accuracy is higher.

<Embodiment> Hereinafter, the present invention will be described in detail based on a basic embodiment when the present invention is applied to a magneto-optical recording disk.

In FIG. 1, a magneto-optical recording disk 1 which is a typical example of the present invention has a disk-shaped substrate 2 whose outer peripheral surface is formed as a truncated cone side surface 2a having a maximum diameter of about 50 to 300 mm. . By providing the truncated cone side surface 2a, the coating layer 5 described later can be provided over almost the entire area of the truncated cone side surface 2a, and the length of the joint surface between the coating layer 5 and the truncated cone side surface 2a is increased. Therefore, it is possible to prevent moisture in the atmosphere from penetrating into the inside from the boundary surface between the truncated cone side surface 2a and the coating layer 5, and further, it is possible to enhance the bonding strength between the both.

Therefore, the inclination angle of the truncated cone side surface 2a is set in consideration of the occurrence of these effects and the width of the recording area, and is preferably set within the range of about 5 to 45 °. In this case, if the tilt angle is less than 5 °, the above-mentioned effect is lost, and if it exceeds 45 °, the recording area becomes too narrow.

On the other hand, this substrate 2 is made of glass or resin (preferably acrylic resin, polycarbonate resin, epoxy resin, polymethylpentene resin, etc.), has a thickness of about 0.5 to 5 mm, and has a hole in the center. It is manufactured in a shape having a part 3. Then, on the surface (substrate main surface) 2b located on the smaller diameter side of the truncated cone side surface 2a of the substrate 2, a layered body 4 having a layer configuration as described later is formed in an annular inner ring on the inner and outer peripheral portions of the substrate 2. It is formed with the peripheral and outer peripheral layered body non-arranged portions provided.

The layered body 4 is, for example, a first protective layer that is in close contact with the substrate 2.
41, a four-layer structure including an intermediate layer 42 formed on the protective layer 41, a recording layer 43 formed on the intermediate layer 42, and a second protective layer 44 which is the uppermost layer. Is configured as. The layered body 4 is formed in a wide annular region from a position inwardly of about 1 to 5 mm from the outer peripheral edge of the substrate main surface 2b to an arbitrary position close to the central hole 3. . The central portion of the annular area serves as the recording area, and the narrow annular area having a width of 1 to 5 mm on the outer peripheral side and the small annular area close to the inner peripheral area serve as the non-recording area 45.

In this case, the corrosion resistance is improved by the annular non-recording area existing on the inner and outer circumferences, particularly on the outer circumference side.

Further, in the recording area on the main surface 2b of the substrate, various groups,
Pits or sector marks can be formed.

Now, the magnetic thin film layer used as the recording layer 43 in the layered body 4 is for magnetically recording the input information by the modulated heat beam or the modulated magnetic field,
The recorded information is reproduced by utilizing the magnetic-optical conversion effect, but the material is not particularly limited.

However, for example, rare earth metals such as Gd, Tb, Dy, and Nd and Fe,
An alloy of a transition metal such as Co is preferably used as an amorphous film formed by sputtering, vapor deposition or the like.
The layer thickness is preferably about 100 to 10000Å.

The other material used for the recording layer 43 is a so-called phase transition type material, for example, a chalcogen-based material disclosed in Japanese Patent Publication No. 54-41902, Japanese Patent No. 1004835, or JP-A-58. -54338 publication, Te dispersed in the Te oxide disclosed in Patent 974257, or Patent No. 974258, tellurium oxide system disclosed in Patent 974257, or, Ge-Sn, Si-Sn and other alloys that produce amorphous-crystalline transitions, or Ag-Zn, Ag-
There are alloys such as Al-Cu and Cu-Al that cause a color change due to a change in crystal structure, and alloys such as In-Sb that cause a change in crystal grain size.

In addition, the first protective layer 41 and / or the second protective layer 44
It is preferable to use an inorganic thin film of various oxides, carbides, nitrides, sulfides, or a mixture thereof of about 300 to 3000 liters, and the corrosion resistance is improved by such a constitution.

Further, as the intermediate layer 42, it is preferable to use various dielectric material layers having a thickness of about 300 to 1500 Å, and the C / N ratio can be improved by providing such a layer.

Further, the layered body 4 is covered with a waterproof coating layer 5 that extends from the inner peripheral layered body non-arranged portion of the substrate 2 along the layered body and extends to the truncated cone side surface. . The thickness of the coating layer 5 is preferably set to, for example, about 1 to 200 μm. As the waterproof coating material used for this purpose, an appropriate material can be mentioned, but for example, a material which cures a radiation-curable compound with ultraviolet rays or electron beams is preferable.

Due to the presence of the coating layer 5, corrosion of the layered body 4 caused by moisture penetrating from the boundary surface between the truncated cone side surface 2a of the substrate 2 and the coating layer 5 can be prevented extremely well. When the coating layer 5 is coated, if the substrate 2 after forming the layered body 4 is rotated and a necessary thickness of, for example, the composition is applied and then the composition is photocured, the accuracy of the external dimensions is extremely good. Will be things.

The magneto-optical recording disk 1 of the illustrated example having such a configuration
Then, a magnetic field is applied from the outside of the main surface side of the substrate (upper side of the figure), and light is emitted from the opposite direction (lower side of the figure) to perform recording or reproduction. In this case, this single-sided recording disc
If necessary, a protective plate may be attached to the side facing the magnetic head (not shown).

FIG. 2 shows an embodiment in which a double-sided recording type magneto-optical recording disk is constructed by using two magneto-optical recording disks shown in FIG.

In this double-sided recording type magneto-optical recording disk 1, two optical recording disks 1 having the structure shown in FIG. 1 are adhered to each other with an adhesive 6 so that each recording layer 43 is enclosed. It is configured by

In this case, the layer thickness of the adhesive 6 is set to about 1 to 200 μm, and as the adhesive used for this, a known appropriate adhesive such as a hot melt adhesive, a thermosetting adhesive, or an anaerobic adhesive is used. Various materials such as a UV-curable adhesive can be used.

 FIG. 3 shows another embodiment of the present invention.

In this magneto-optical recording disk 1, a protective coat 7 having a thickness of about 1 to 150 μm is formed on the upper surface of the layered body 4 and the side surfaces on the inner peripheral side and the outer peripheral side, and the coating layer 5 is formed thereon. Is coated.

As a material for the protective coat 7, various organic substances can be used, but a radiation-curable compound having an acrylic double bond cured with radiation such as electron beam or ultraviolet ray is used. Is preferred. By providing such a protective coat 7, the corrosion resistance is further improved.

As described above, in various optical recording disks, the presence of the coating layer 5 causes the truncated cone side surface 2a of the substrate 2 to be formed.
Corrosion of the layered body 4 caused by moisture penetrating from the boundary surface between the coating layer 5 and the coating layer 5 can be prevented extremely well.

Next, the results of experiments conducted to confirm the effect of the present invention will be shown.

[Experimental example] The first protective layer 41 of borosilicate glass was formed on the substrate 2 made of bisphenol A-based optical disc grade polycarbonate resin having a diameter of 130 mm, a hole diameter of 15 mm and a thickness of 1.2 mm by high frequency magnetron sputtering to a film thickness of 400 Å. Then, an intermediate layer 42 (Si ₃ N ₄ ) was further formed thereon by a high frequency magnetron sputtering so as to have a film thickness of 800 Å.

On such a first protective layer 41 and an intermediate layer 42, 21
An at% Tb, 68 at% Fe, 7 at% Co, 4 at% Cr alloy thin film was sputtered to a thickness of 800 Å to form a magnetic thin film recording layer 43.

Further, the second protective layer 44 of borosilicate glass described above was deposited on the recording layer 43 by high-frequency magnetron sputtering so as to have a film thickness of 1000 Å to form a layered body 4. The recording layer 43 was formed in an annular region with a radius of 21 to 63 mm from the center of the substrate.

Then, as the radiation-curable compound used for the coating layer 5 that covers the upper surface and the side surface of the layered body 4, a coating composition containing a polyfunctional oligoester acrylate and a photosensitizer is used, and the composition is spinner-coated. Layered. The layering area of the coating layer 5 was from a position 2 mm closer to the hole 3 direction from the inner peripheral surface of the layering body 4 to a position near the end of the substrate main surface 2b. After applying such a coating composition, ultraviolet rays are
It was irradiated for 2 seconds to be crosslinked and cured to obtain a cured film having a film thickness of 20 μm.

The optical recording disk thus manufactured is bonded to obtain a comparative sample A.

Next, an optical recording disk sample B of the present invention was produced using the basic configuration example of FIG.

In this case, the diameter 13 of the large diameter portion of the truncated cone side surface 2a of the substrate 2
It was set to 0 mm, and the side surface 2a of the truncated cone was set to have an inclination of 16 °. The element conditions other than this were set to be the same as those of the sample A to manufacture.

Then, in Sample B, as the coating layer 5, the binder containing the above-mentioned polyfunctional oligoester acrylate and the photosensitizer was used, and coating was performed according to the above-mentioned procedure, and in the case of Comparative Sample A while rotating. Cured as well.

The sample B produced in this way is the disc 1
There was no protrusion of the coating material 5 on both the outer peripheral side and the inner peripheral side, and the outer diameter and inner diameter accuracy was 0.6 mm or less. In Samples A and B, the recording layer 43 is 30 mm or less inside and outside.
The non-recording area was 61.4 mm or more. Further, an optical recording disc sample C for comparison was prepared in the same manner as the sample B except that the non-recording area of the layered body was deleted from the optical recording disc sample B.

A weather resistance test was conducted on the samples A, B and C thus produced.

The test conditions were 80 ° C., 80% relative temperature, 800 hours of storage, and immersion in a 0.2N hydrochloric acid aqueous solution for storage. The bit error rate of the EFM signal was measured at the outer edge of the recording area after the storage and at the initial stage.

 The results are shown in Table 1.

As shown in Table 1, it becomes clear that a remarkable effect is obtained when using the present invention.

Although several embodiments have been described above, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.
For example, the generatrix on the side surface of the truncated cone is not limited to a straight line but may be set to an appropriate curve, and the generatrix can be applied to various optical recording disks.

[Brief description of drawings]

FIG. 1 is a sectional structural view showing a basic embodiment of an optical recording disk according to the present invention, and FIG. 2 is a double-sided recording type optical recording disk using two optical recording disks shown in FIG. FIG. 3 is a sectional configuration diagram showing an example in which a protective coat is provided between the layered body and the coating layer of the optical recording disk shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Magneto-optical recording disk 2 ... Substrate 2a ... Frustum side surface 2b ... Substrate main surface 3 ... Hole 4 ... Layer body 41 ... First protective layer 42 ... Intermediate layer 43 ... Recording layer 44 ... Second Protective layer 5 ... coating layer 6 ... adhesive 7 ... protective coat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Takayama 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (56) References JP-A-63-48631 (JP, A) JP-A-60 -121549 (JP, A) JP 61-21113 (JP, A) JP 63-837 (JP, A)

Claims (3)

(57) [Scope of utility model registration request] 1. A surface in which an outer diameter of a layered body forming surface in which an outer peripheral surface of a disk-shaped substrate having a circular hole in a central portion is in contact with an annular layered body including a recording layer is not in contact with this layered body. Is formed on a side surface of a truncated cone smaller than the outer diameter of the layered body, and the layered body is arranged on the substrate in a state where annular inner and outer layered body non-arranged portions are left in the inner peripheral portion and the outer peripheral portion. In addition, an annular recording area is provided in the central portion in the radial direction, and the inner peripheral portion and the outer peripheral portion thereof are non-recording areas, and the layered body is formed from the inner peripheral layered body non-arranged portion of the substrate, An optical recording disk, which is covered with a waterproof coating layer extending along the layered structure and extending to the side surface of the truncated cone, and the coating layer further covers the entire side surface of the truncated cone. 2. The optical recording disk according to claim 1, wherein the entire covering layer is arranged inside the outer diameter of the surface not in contact with the layered body. 3. An optical recording disc in which two optical recording discs according to claim 1 or 2 are adhered to each other in such a manner that the respective layered bodies are contained therein.