JPH07192312A - Optical recording medium - Google Patents

Abstract

PURPOSE:To improve adhesion of a protecting layer to a UV curing resin layer and to prevent penetration of water from a end surface of an outer edge part. CONSTITUTION:The subject medium has at least a UV curing resin layer 12 and recording layer 14 on a disk-shaped substrate 11, and this recording layer 14 is formed on more inside than the outer edge part in the radial direction of this UV curing resin layer 12. This recording layer 14 is preferably formed on more inside, at least >=1mm than the outer edge part in the radial direction of a resin forming region of this UV curing resin layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium capable of recording / reproducing / erasing information by using light.

[0002]

2. Description of the Related Art Among optical recording media capable of recording / reproducing / erasing information by using light, recording films used especially for optical disks include rare earth-transition metal alloy thin films and amorphous. Known are reducing oxide thin films, organic dye-based thin films, and the like, which utilize a phase change from crystalline to crystalline. Among them, the magneto-optical recording medium composed of a rare earth-transition metal alloy thin film is considered to be superior to other mediums in terms of film formability, recording sensitivity and reproduction signal quality. Examples of media belonging to this type include polycrystalline thin films such as MnBi, GdCo, and GdF.
e, TbFe, GdTbFe, GdFeCo, TbFe
Such as Co.

A transparent disk made of glass or a synthetic resin material has been used as a substrate. Of these, in glass and some resin substrates, the guide groove is not directly formed in the substrate, but an ultraviolet curable resin layer in which the groove is transferred from a stamper is formed on the surface. On the other hand, other synthetic resin material substrates have grooves formed during injection molding.

[0004]

However, in the case of the conventional optical recording medium, an amorphous magnetic material containing a rare earth element generally has a property of being easily corroded, and is corroded when exposed to the atmosphere or water vapor. There is a problem that the characteristics are deteriorated. In addition, characteristic deterioration due to oxidation is also observed in the reducing oxide thin film and the organic dye-based recording film that utilize the phase change.

Therefore, conventionally, in order to solve such a problem, measures such as forming an inorganic protective film on the recording layer formed of an amorphous magnetic alloy thin film, and further forming an organic protective film are taken. Has been applied. In addition, in the pasting type disc, an air sandwich structure in which the recording layer is sealed with an inert gas or a close pasting structure in which the entire surface is adhered with a resin has been adopted. However, if the inert gas is completely sealed by the air sandwich structure, there is a problem that if the atmospheric pressure is lowered during transportation, the volume of the internal gas increases and the disk is destroyed. For this reason, it is necessary to provide a ventilation hole at the outer edge of the adhesive layer, and the outside atmosphere intrudes from there, so that the oxidation of the recording film cannot be completely suppressed.

Further, in the case of a close-bonded structure disc using a resin substrate, atmospheric air may pass through the substrate or enter from the outer edge of the adhesive portion, so that oxidative deterioration may occur in the entire recording film when used for a long period of time. Was unavoidable. Further, in the case of a glass substrate disk, since the atmosphere does not pass through the inside of the substrate, the oxidation deterioration is suppressed as compared with the resin substrate disk, but the oxidation due to the water entering from the outer edge of the adhesive portion cannot be suppressed. Therefore, in order to improve the reliability of the disk, how to suppress the intrusion of water from the end surface of the outer edge portion has been a problem.

The present invention has been made in view of the above circumstances, and solves the drawbacks of the conventional optical recording medium, improves the adhesion, and suppresses the intrusion of water from the end surface of the outer edge portion. It is an object of the present invention to provide an improved new optical recording medium that can be used.

[0008]

In order to solve the above problems, the present invention provides an optical recording medium having at least an ultraviolet curable resin layer and a recording layer on a disk-shaped substrate, wherein the recording layer is the ultraviolet curable resin layer. An optical recording medium is formed on the inner side of the outer edge portion in the radial direction of (1).

According to the present invention, the recording layer is formed at least 1 mm inside the outer edge of the resin forming region of the ultraviolet curable resin layer in the radial direction (claim 2). The protective layer is sealed by a protective layer (Claim 3), the protective layer is a dielectric protective layer and / or an organic protective layer (Claim 4), and the outer edge portion in the radial direction of the ultraviolet curable resin layer is The aspect is that it is formed at least 1 mm inside from the outer edge portion in the radial direction of the substrate.

[0010]

A magneto-optical recording disk will be described as an example of the present invention. For example, as shown in FIG. 1, the magneto-optical disk (1) comprises a disk-shaped glass substrate (11) and a tracking on it. The ultraviolet curable resin layer (12) formed with the groove for use, the dielectric film (13) provided thereon, the recording film (14) provided on the dielectric film (13), and the recording film ( Two single plate disks formed by a dielectric film (15) provided on the dielectric film (15) and an organic protective film (16) provided on the dielectric film (15) are bonded via an adhesive agent 17. Are joined together.

In this case, the total thickness of the glass substrate (11) and the groove-formed UV curable resin layer (12) is usually about 0.5 mm to 2.0 mm. Glass substrate (1
As for 1), the one whose surface is chemically strengthened can be used if necessary. The thickness of the reinforcing layer is 1 to 100 μm.
Further, the end face of the outer edge portion is chamfered as necessary. Further, in order to improve the adhesion between the glass substrate (11), the ultraviolet curable resin (12) formed thereon, and the organic protective film (16) formed later, the substrate surface is treated with a silane coupling agent or the like. It is also effective to process them.

The ultraviolet curable resin layer (12) has a thickness of 10 to 50 μm and is formed on a flat portion inside the chamfered portion.
It is preferable that the outer peripheral portion of the formation region is formed at least 1 mm or more inside the outer edge portion of the substrate. UV curable resin layer (1
The dielectric film (13) formed on 2) is, for example, Z
nS, SiO, SiO ₂ , SiN _x , AlN, AlO
It is made of a dielectric material such as N or CaF ₂ . Transmembrane pressure is 5
0 to 150 nm.

The recording film (14) formed on the dielectric film (13) is, for example, GdFe, TbFe, DyF.
e, GdFeCo, TbFeCo, DyFeCo, Gd
TbFe, GdTbFeCo, TbDyFe, TbDy
It is formed from a magneto-optical recording material such as FeCo, MnBi, MnCuBi, or GdlG. Such recording film (14)
Has a thickness of 15 to 200 nm. Further, as other materials to which the present invention is applied, there are known known materials capable of optical recording. For example, Te-based pit-forming recording material or A
s-Te-Ge system, Sn-Te-Se system, TeOX system,
A recording material such as Sb ₂ Se ₃ by a phase change may be used.

A dielectric film (15) is formed on the recording film (14).
Is provided. ZnS, SiO, SiO ₂ , SiN _x ,
It is formed of a material such as AlN, AlON, or CaF ₂ .
The membrane pressure is 50 to 150 nm. The present invention is characterized in that the dielectric films (13) and (15) and the recording film (14) have an innermost and outermost peripheral portion of at least 1.0 mm or more from the outer peripheral portion of the formation region of the ultraviolet curable resin (12). It is formed so as to form.

The organic protective film (16) formed on the dielectric film (15) is made of an ultraviolet curable resin such as an ultraviolet curable epoxy acrylate, urethane acrylate or polyester acrylate. These can be applied by spin coating and then cured by UV irradiation. The membrane pressure is 1 to 20 μm. The inner peripheral side of the formation region is outside the ultraviolet curable resin (12) and inside the recording film (14) and the dielectric film (13) and (15) formation regions. The outer peripheral side is up to the outer edge of the substrate (11). By limiting the formation region of the organic protective film (16) in this way, the organic protective film (16) is formed outside the region where the dielectric films (13), (15) and the recording film (14) are formed. A region where the UV curable resin (12) is directly bonded is secured, and high adhesion durability can be obtained.

On the organic protective film (16), an adhesive (1
7) is applied, and the other disk is attached with the organic protective films facing each other. Examples of the adhesive in this case include hot-melt adhesives, thermosetting adhesives, and ultraviolet / heat combined curing adhesives. As a coating method, an appropriate method such as a roll coating method or a method of coating a liquid resin with a dispenser is adopted.

Of course, the present invention has been described above by taking the bonded type disk as an example, but it goes without saying that the present invention is also effective when used in a state where the bonded type disks are not bonded. As described above, in the optical recording medium of the present invention, a region where the organic protective layer (16) and the ultraviolet curable resin (12) are bonded is secured within a range of 1.2 mm or more in the outer circumference of the recording film forming region. When the disc is exposed to a water-rich environment for a long time, peeling occurs in the region directly bonded to the glass substrate (11), but peeling is observed in the region bonded to the ultraviolet curable resin layer (12). Absent. Therefore, in the vicinity of the recording film formation region, the moisture protection function of the organic protective film is maintained. In the case of a magneto-optical recording medium, in order to obtain durability equivalent to 10 years in an actual use environment, the organic protective film and the ultraviolet curable resin layer should be formed at least 1.2 mm or more from the outer circumference of the recording film forming area. Must be glued.

Further, if the ultraviolet curable resin layer is formed too much on the inner periphery, the peeled region of the organic protective film spreads, and a large amount of moisture enters from the outside, which accelerates the oxidation of the recording film. . In order to obtain durability equivalent to 10 years of actual use environment, it is desirable that the ultraviolet curable resin layer is formed from the outer edge of the substrate, and when a virtual circle is drawn 1.3 mm inside, the outer circumference is It must be formed so that it is not inside. As a result, the area where the organic protective film and the glass substrate are bonded is narrowed, and it is possible to minimize the intrusion of water due to peeling.

The present invention will be described in more detail below with reference to examples. Of course, the present invention is not limited to the following examples.

[0020]

Example 1 A glass substrate surface having a diameter of 12 inches and a thickness of 1.2 mm was prepared.
A 1% isopropyl alcohol solution of silane coupling agent KBM403 manufactured by Shin-Etsu Chemical was applied, dried at room temperature for 5 minutes, and then heat-treated at 150 ° C. for 20 minutes. Next, 50 parts of 2-ethylhexyl acrylate, 27 parts of butanediol diacrylate, and 2 parts of trimethylolpropane triacrylate on the stamper surface where the information track is present.
Ultraviolet curable liquid resin consisting of 1 part and 2 parts of benzoin isobutyl ether is applied in a concentric circle around a radius of 100 mm, a glass substrate is put on this and the upper part of the substrate is pushed so that the resin spreads isotropically at the same speed. It was

When the liquid resin reaches the outermost peripheral portion and the innermost peripheral portion, leaving the chamfered portion of the substrate, the pressing of the substrate is stopped, and the pressure of about 1000 is applied from the substrate side in a nitrogen atmosphere with a 2 kw medium pressure mercury lamp.
It was irradiated with mJ ultraviolet rays. After that, when the substrate was peeled off from the stamper, an ultraviolet curable resin layer on which information tracks of the stamper were transferred was formed on the substrate surface. In the portion where the liquid resin spreads the slowest, the tip of the spread was at a position of 1.0 mm to the outermost peripheral portion of the substrate. The thickness of the ultraviolet curable resin layer was 40 to 50 μm.

Next, a dielectric protective film and a recording film were formed on this substrate by sputtering. At this time, the inner and outer peripheral portions of the sputtered film forming area are about 1.0 mm larger than the ultraviolet curable resin layer forming area.
I made it narrower. The formed films are the SiN film 70 nm and the TbFeCo film 100 n in order from the substrate.
and the SiO ₂ film was 50 nm. An organic protective film was formed on the SiO ₂ film. After applying a UV curable liquid resin (SD301 manufactured by Dainippon Ink and Chemicals) with a spin coater, the resin was cured by irradiating about 1000 mJ of UV light with a high pressure mercury lamp under a nitrogen gas stream. The innermost circumference of the organic protective film forming area was in the middle of the ultraviolet curable resin layer forming area and the recording film forming area, and the outermost circumference was the outer peripheral end surface of the substrate.

The two prepared single-disks were coated with a hot-melt adhesive (XW30 manufactured by Toagosei Kagaku Co., Ltd.) in a thickness of about 30 μm on the surface on which the organic protective film was formed, and then pressure-bonded. . When the magneto-optical disk thus prepared was left in an environment of 85 ° C. and 90% humidity for 1000 hours, no corrosion was observed on the entire surface of the recording film forming area. Comparative Example A part of the ultraviolet curable resin region was 4.0 from the outer periphery of the flat portion of the substrate.
The inorganic protective film and the recording film are formed so as to reach the inner side up to mm.
A disk was prepared in the same manner as in the example except that the disk was formed so as to have a thickness of 3.5 mm to 3.5 mm. When this disc was left in an environment of 85 ° C. and 90% humidity for 1000 hours, corrosion occurred in the recording film at the place where the recording film was formed up to the outer periphery of the ultraviolet curable resin layer.

[0024]

According to the present invention, in an optical recording medium having at least an ultraviolet curable resin layer, a recording layer, a dielectric layer and an organic protective layer on a substrate, the recording layer is provided more than the outer edge portion of the ultraviolet curable resin forming area. When the protective layer is formed on the inner side of 1.2 mm or more and then sealed with the protective layer, the adhesion between the protective layer and the ultraviolet curable resin layer is improved, and it is possible to suppress the intrusion of water from the end face of the outer edge portion. Further, the outer edge of the ultraviolet curable resin layer forming region is 1.3
By forming it so that the position is within mm, the adhesiveness between the organic protective layer and the substrate is improved, and it becomes possible to suppress moisture intrusion from the end face of the outer edge portion.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view illustrating the structure of a magneto-optical disk according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 11 Substrate 12 UV curable resin layer 13 Dielectric film 14 Recording film 15 Dielectric film 16 Organic protective film 17 Adhesive

Claims (5)

[Claims] 1. An optical recording medium having at least an ultraviolet curable resin layer and a recording layer on a disk-shaped substrate,
The optical recording medium, wherein the recording layer is formed inside an outer edge portion of the ultraviolet curable resin layer in the radial direction. 2. An optical recording medium, wherein the recording layer according to claim 1 is formed at least 1 mm or more inside the outer edge portion in the radial direction of the resin forming region of the ultraviolet curable resin layer. 3. An optical recording medium, wherein the recording layer according to claim 1 or 2 is sealed by a protective layer. 4. An optical recording medium, wherein the protective layer according to claim 3 is a dielectric protective layer and / or an organic protective layer. 5. The medium of claim 1, claim 2, claim 3, or claim 4, wherein the outer edge portion of the ultraviolet curable resin layer in the radial direction is formed at least 1 mm or more inward from the outer edge portion of the substrate in the radial direction. An optical recording medium characterized by being provided.