JPH05242538A - Manufacturing method of magneto-optical recording medium - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a highly reliable magneto-optical recording body capable of preventing the attraction and contact of the flying head to the resin protective layer of the magneto-optical recording body as much as possible. [Structure] At least an optical recording layer and a resin protective layer are sequentially laminated on one main surface of a substrate, and then a local convex portion generated on the surface of the resin protective layer is ground to be flattened,
By making the surface of the resin protective layer a maximum height of 2 μm or less, adsorption of the flying head to the resin protective layer of the magneto-optical recording body and contact during flying of the head can be prevented as much as possible. It is possible to provide a highly reliable magneto-optical recording medium having stable flying characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magneto-optical recording body having at least an optical recording layer formed on one main surface of a substrate.

[0002]

2. Description of the Related Art At present, magneto-optical disks such as a write-once type in which recorded information can be written only once and a rewritable type in which information can be rewritten can be developed and put into practical use. These magneto-optical disks are usually used in which an optical recording layer and a protective layer for protecting the optical recording layer are sequentially laminated on a substrate.

Among such magneto-optical disks, in which a flying head is used for writing information, the flying head malfunctions when the flying head comes into contact with the surface of the protective layer when the magneto-optical disk starts and stops rotating. However, there is a problem that the optical recording layer is damaged due to scratches or cracks in the protective layer.

Therefore, it has been proposed that a lubricant or a filler be mixed into the resin layer as the protective layer to improve the surface hardness of the protective layer and to provide lubricity, thereby eliminating the problem caused by the contact of the flying head. (Japanese Patent Laid-Open No. 2-40
(See Publication No. 149). Further, it has been proposed that a roughened resin layer is laminated on a protective layer to prevent adsorption of a flying head and avoid sliding friction and impact of the flying head (see Japanese Patent Application Laid-Open No. 2-2323636).

[0005]

However, in any of the above proposals, foreign matter such as dust is mixed in when a resin layer is formed to locally generate projections (projections), or the size of the filler or its aggregation causes local protrusions. Since the flying head comes into contact with the convex portion due to the generation of the convex portion, a malfunction also occurs as in the conventional case and the reliability of information recording is lowered, which is a problem.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly reliable magneto-optical recording medium which solves the above problems and can prevent the flying head from adsorbing or coming into contact with the resin protective layer of the magneto-optical recording medium as much as possible.

[0007]

According to the method of manufacturing a magneto-optical recording medium of the present invention, at least an optical recording layer and a resin protective layer are sequentially laminated on one main surface of a substrate, and thereafter the resin protective layer is formed on the surface. The local convex portions are ground to be flattened so that the surface of the resin protective layer has a maximum height of 2 μm or less. Here, the optical recording layer means a layer including at least a magneto-optical recording layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail with reference to the drawings. The magneto-optical recording medium M shown in FIG. 1 is a disk-shaped substrate 1 (having a thickness of 1.2
mm) on one main surface, the optical recording layer 2 is formed by the sputtering method,
Further, the resin protective layer 3 is formed by spin coating.

Here, the optical recording layer 2 is composed of a first dielectric layer of amorphous yttrium sialon (thickness of about 100 nm) and amorphous Gd.
-Dy-Fe-based magneto-optical recording layer (about 20 nm thick), a second dielectric layer of amorphous yttrium sialon (about 30 nm thick), and a reflective layer of metallic aluminum (about 100 nm thick) are sequentially laminated. Is. Other materials for the first and second dielectric layers include silicon nitride, aluminum nitride, silicon carbide,
Cadmium sulfide, titanium nitride, zinc sulfide, magnesium fluoride, cadmium oxide, bismuth oxide and the like are used alone or in combination. Further, especially as the material of the magneto-optical recording layer, in addition to the Gd-Dy-Fe system, for example, Gd-Dy-Fe, Gd-Tb-Fe,
Tb-Fe-Co, Dy-Fe-Co, Gd-Tb-Dy-Fe, Gd-Tb-Fe-Co, Tb-Dy-Fe
-Co, Gd-Dy-Fe-Co, Nd-Gd-Dy-Fe, Nd-Dy-Fe-Co, Nd-Gd-Dy-F
An alloy system such as e-Co system is used. In addition, as the material of the reflective layer, Cr, Ti, Cu, Ag, SUS, etc. are used alone or in combination.

The resin protective layer 3 includes a lower layer 4 and an upper layer 5.
It consists of and. Here, the lower layer 4 is a urethane acrylate-based ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals; trade name)
SD-301) is applied and formed to a thickness of about 10 μm, and the upper layer 5 is a resin (Mitsubishi Rayon) in which silica filler (particle size 1 to 10 μm, average particle size 4 μm) is added to acrylic UV curable resin. (Made by the company) is applied and formed to a thickness of about 5 μm. As the material of the lower layer 4 and the upper layer 5, in addition to the above materials, for example, acrylic, epoxy, polyester,
Acrylic ester-based, urethane acryl-based, polyether-based, silicone-based, etc. ultraviolet curable types, heat curable types, anaerobic curable types, moisture curable types and the like can be used.

In addition to the above materials, the filler of the upper layer 5 may be a mixture of a resin with a ceramic such as Al ₂ O ₃ , Si ₃ N ₄ , SiC, CdS, ZnS or SiO. Some ceramics such as ITO (In ₂ O _{3 with} SnO ₂ added), Sb ₂ O
₃ , IrO ₂ , MoO ₂ , NbO ₂ , PtO ₂ , RuO ₂ , WO _{2 and} other oxides, MoC, NbC, TaC, TiC, WC and other carbides, NbN, Ta ₂ N, TiN, Zr
Nitride such as N and VN may be mixed.

Regarding the layer thickness of the protective layer 3, since the distance between the flying head and the optical recording layer 2 is actually 25 μm or less, the layer thickness of the lower layer 4 is required to be reliable for organic materials such as resin. The optimum value is 2 to 20 μm, preferably 4 to 15 μm. The upper layer 5 preferably has a particle size of 4 to 8 μm, depending on the particle size of the filler, and the film thickness at that time is 4 to 8 μm.
m is good.

The surface of the upper layer 5 is roughened by the filler, and the height of the convex portion locally generated by the agglomeration of the filler or foreign matters such as dust becomes unevenness of 4 to 10 μm. Next, using a vanishing head type grinding head generally used in hard disks, etc., the maximum height of the convex portion is 0.05 to 3.0 μm while rotating the magneto-optical recording medium M.
Many samples were prepared. The height was measured by measuring the height from the bottom to the apex of the protrusion with a stylus type surface roughness meter. Further, the upper layer 5 was formed by coating so that the surface roughness of each sample was about 100 nmRa in terms of centerline roughness.

A levitation test by the flying head 6 for each sample (rotational speed of the magneto-optical recording medium 3600 rpm,
When the flying head 6 was loaded with a load of 4 g), the flying head 6 contacted the magneto-optical recording medium M as shown in FIG. 2 when the maximum height of the protrusion was 2.5 μm or more. Also, when the maximum height of the convex portion is smaller than 0.1 μm, the flying head 6 is adsorbed and the surface roughness is about 10% of the initial value.
It was considerably reduced from 0 nmRa to about 10 nmRa. On the other hand, when the maximum height of the convex portion was 0.1 to 2.0 μm, no contact or adsorption of the flying head 6 to the magneto-optical recording medium M was observed, and the surface roughness maintained the initial value of about 100 nmRa. . The surface roughness is measured by a surface roughness meter, and the average value of the center line average roughness (measurement length = 2 mm) along the diameter direction of the magneto-optical recording material is calculated.

The surface roughness of the upper layer 5 is not limited to that in this embodiment, and the maximum height of the convex portion is 0.1 to 2.0.
In the case of μm, no contact or adsorption of the flying head 6 to the magneto-optical recording medium M was observed, and it was found that the surface roughness maintains the initial roughness. Further, the mode of the resin protective layer is not limited to the above-mentioned configuration, and may be appropriately changed and implemented as long as the surface is roughened by sandpaper or the like.

[0016]

As described above, according to the method for manufacturing a magneto-optical recording medium of the present invention, it is possible to prevent the flying head from adsorbing to the resin protective layer of the magneto-optical recording medium or contacting the head during flying. Thus, it is possible to provide a highly reliable magneto-optical recording body with stable flying characteristics of the flying head.

[Brief description of drawings]

FIG. 1 is a sectional view of a magneto-optical recording medium according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a magneto-optical recording body showing a state where a flying head is in contact with a resin protective layer.

[Explanation of symbols]

1 ・ ・ ・ Substrate 2 ・ ・ ・ Optical recording layer 3 ・ ・ ・ Resin protective layer 4 ・ ・ ・ Lower layer 5 ・ ・ ・ Upper layer 6 ・ ・ ・ Flying head M ・ ・ ・ Magneto-optical recording material

Claims (1)

[Claims] 1. An optical recording layer and a resin protective layer are sequentially laminated on one main surface of a substrate, and the surface of the resin protective layer is then flattened by grinding so that the surface of the resin protective layer has a maximum height. A method of manufacturing a magneto-optical recording material, which has a surface of 2 μm or less.