JPH0479045A - Magneto-optical disk and production thereof - Google Patents

Abstract

PURPOSE:To facilitate mass production by consisting the outermost layer of the magneto-optical disk of a photosetting resin layer formed with fine physical ruggedness on a surface layer. CONSTITUTION:A recording film of a single layer or multilayered recording films 2 consisting of a dielectric film, recording film, reflecting film, etc., are formed by vapor deposition or sputtering on a transparent substrate consisting of glass, polycarbonate, etc., and further, a protective layer 3 consisting of a UV curing type resin is applied thereon for the purpose of protecting these films. A resin of an acrylate type, for example, urethane acrylate, etc., are used as the UV curing type resin 4 for forming texture consisting of the material different from the material of the protective layer 3. The texture treatment of the magneto-optical disk is executed in large quantity in this way.

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to a magneto-optical disk used in a magneto-optical recording and reproducing device using a floating head and a method for manufacturing the same, and further relates to a method for surface treatment thereof. It is related to.

(b) Conventional technology The magneto-optical recording method is a recording medium in which a perpendicularly magnetized film made of a metal magnetic material is formed on a substrate made of glass, plastic, ceramics, etc., and recording is performed using the following method.
It performs regeneration.

That is, when recording, the recording medium is first initialized by a strong external magnetic field, etc., and the direction of magnetization is set in one direction (upwards,
or downward). After that, a laser beam is irradiated onto the recording area to heat the temperature of the medium to above the Curie point or near the compensation point, and the coercive force (He) of that area is reduced to zero or almost zero. Then, an external magnetic field (bias magnetic field) opposite to the initialization direction of magnetization is applied to reverse the magnetization direction. When the laser beam irradiation is stopped, the recording medium returns to room temperature, so the recording medium is reversed, the f-co magnetization is fixed, and information is recorded magnetically.

During reproduction, a different linearly polarized laser beam is irradiated onto the recording medium, and the phenomenon (magnetic Kerr effect, magnetic Faraday effect) is utilized that the rotation of the polarization plane of reflected light and transmitted light differs depending on the direction of magnetization. and read out optically.

The magneto-optical recording method described above is attracting attention as a rewritable large-capacity memory element, but there are two ways to rewrite information on the recording medium: 1) re-initializing the recording medium; There are two methods: 11) a method in which the recording medium is overridden by modifying the external magnetic field generator, that is, a method in which the information is directly rewritten without performing an erasing operation.

Among them, method 1) requires an initialization device or two heads, which leads to an increase in cost. Second, if only one head is provided and this is used for erasing, it will take the same amount of time for erasing as for recording, which is inefficient.

On the other hand, in the method of devising a recording medium that satisfies (l),
It is difficult to control the composition, film thickness, etc. of the recording medium. Therefore, the most practical method is to devise an external magnetic field generator in step 11), that is, to keep the laser beam constant and record by reversing the direction of the external magnetic field by high-speed switching.

By the way, in order to quickly reverse the direction of the external magnetic field, it is necessary to make the coil and coil core in the external magnetic field generating device extremely small, and in that case, the area where the magnetic field is generated becomes small. Therefore, it is necessary to place the magnetic head and the recording medium close to each other, so generally, as shown in FIG.
The external magnetic field generator is a slider-type floating head It that can slide on a recording medium (not shown), and this floating head F
' The magnetic head part 13 is attached to the slider part 12 in 11.
At the same time, the floating head 11 is placed in suspension I.
The floating head 11 is supported by O and biased toward the recording medium, and as the recording medium rotates, the flying head 11 is made to float above the surface of the recording medium. 9 is a base that supports the suspension 10.

The flying head 11 maintains a constant flying height by balancing the upward flying blade generated by the air flow between the slider section 12 and the recording medium and the downward biasing force of the suspension 10. This type of floating head is also used in existing node disks,
The flying height in a hard disk is on the order of submicrons.

On the other hand, when the recording medium is a magneto-optical disk, due to its portability, the rate of dust adhering to the disk increases, and if the disk is placed too close to the disk, crashes may occur.Secondly, the hard disk It is necessary to increase the flying height compared to the case of 1. In this case, the flying height is required to be 5 to 15 μm.

Furthermore, fine physical irregularities (hereinafter referred to as texture) are formed on the surface of the magneto-optical disk on the flying head side so that the disk surface and the surface of the flying spatula 11I do not attract each other. This texture is shown in Figure 6 (
As shown in a) and (b), the textured tape 15 having minute irregularities on the surface is pressed onto the magneto-optical disk I4 by the tape pressing roll 16, and the tape 15 is pressed onto the magneto-optical disk I4.
is formed by moving the magneto-optical disk 14 in the direction of arrow C and rotating the magneto-optical disk 14. In this case, disk 1
4 and the feeding direction of the tape 15, the resulting texture has a direction as shown by the two-dot chain line in FIG. It is formed like this.

(c) Invention or problem to be solved By the way, as mentioned above, in order to form a texture, it is necessary to process the texture tape by pressing it onto each disk one by one, which increases the cost and is not suitable for mass production. Oh ni. Furthermore, during processing, unnecessary stress is applied to the magneto-optical disk, and dust and dirt may adhere to the disk, contributing to a decrease in quality.

The present invention has been made in consideration of the above circumstances, and includes a magneto-optical disk and a method for manufacturing the same, which form retexture by curing a photocurable resin in two stages and which are easy to mass produce. This is what we are trying to provide.

(D) Means for Solving the Problems The present invention provides a magneto-optical disk characterized in that it is comprised of a photo-curing resin layer having minute physical irregularities formed on its outermost layer or surface layer. A photocurable resin is applied to the surface of a substrate on which a recording film is formed, and the photocurable resin is irradiated with light to harden only the surface layer, and then the wavelength of the light is shortened and the irradiation is performed. This method of manufacturing a magneto-optical disk is characterized in that the inner layer of the photocurable resin is cured to form fine physical irregularities on the surface layer of the photocurable resin.

As the photo-curable resin layer in the present invention, for example, a UV-curable resin layer can be used, and this is cured in two stages using light and UV light.

The physical irregularities in the present invention may be rough on the inner circumferential portion of the surface layer of the photocurable resin layer and may be finer on the outer circumferential portion than the inner circumferential portion.

2. Physical irregularities: They can be formed by varying the amount of light irradiation between the outer and inner peripheries. By forming physical irregularities in this manner, the flying height of the flying head is kept constant.

(E) Effects According to the present invention, it is possible to carry out a large amount of texture processing on magneto-optical disks, and furthermore, the flying height of the flying head does not change significantly.

(f) Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following examples.

Embodiment 1 FIG. 1 shows a sectional view of a magneto-optical disk having a textured shape according to the present invention.

(2) is a transparent substrate made of glass, polycarbonate, polymethyl methacrylate, or amorphous polyolefin, on which is a single-layer recording film or dielectric film;
A multilayer recording film 2 consisting of a recording film, a reflective film, etc. is formed by vapor deposition or sputter linking, and a protective f
A protective layer 3 made of a U-curing resin is coated thereon. 4 is a texture-forming UV curable resin made of a material different from that of the protective layer 3. Note that the protective layer 3 does not necessarily need to be coated, and the texture-forming UV curable resin 4 may also serve as the protective layer 3. As the texture forming UV curable resin 4, acrylate resin such as urethane acrylate,
Epoxy acrylate, polyol acrylate, etc. can be used.

Next, a method for manufacturing a magneto-optical disk according to the present invention will be explained using FIG.

5 is a magneto-optical disk body on which a recording film 2 is formed;
The upper side in the figure shows the side on which the protective film 3 is formed. (, i) in Figure 2 is the resin coating process, for example, RAY
A texture-forming UV curable resin 4 made of screen printing ink such as VEX 5C82F (trade name, Dainippon Ink Chemicals (Aji)) is applied.

(b) and (c) in Fig. 2 are UV curing processes, in which a textured shape is formed by performing surface curing and internal curing in two stages (the magneto-optical method of the present invention The disc uses Union Carbide's UCC PhotoCure Nostem). That is, first, the texture-forming UV curable resin 4 is irradiated with UV light having a long wavelength, for example, UV light L1 having a high energy output at a wavelength of 300 to 400 nm, to harden only the surface layer thereof. Then U
UV light with a shorter wavelength than V light L1, for example, wavelength 200-3
UV light L2 with a large energy output at 00 nm is irradiated to cure the entire texture-forming UV curable resin 4 including the internal layers. This creates a physical irregularity or texture in the surface layer due to the difference in cure shrinkage between the previously cured surface layer and the subsequently cured inner layer.

In addition, when irradiating the Uv light Ll, in order to help cure only the surface layer, N2 gas is added at a rate of, for example, 10.0 m3/h.
It's even better if you let it flow a little.

Embodiment 2 Another embodiment of the present invention will be described below with reference to FIG. 3.4.

In FIG. 3, UV curable resin for texture formation 7
, which differs from that of Example 1 described above, has coarse physical irregularities formed on its inner circumferential portion, and finer physical irregularities formed on its outer circumferential portion than the inner circumferential portion. The configuration other than this is the same as the first embodiment.

The processing method of this embodiment also forms a textured shape by performing surface hardening and internal hardening in two stages. First, as shown in (2L) in Figure 4,
A texture-forming UV curable resin 7 is applied onto the surface of the magneto-optical disk body 5, which is a magneto-optical recording medium, on the side where the protective film is formed. Next, (b) in Figure 4
As shown in FIG. 2, a mask g is placed on the texture-forming UV curable resin 7 so as to substantially shield the outer periphery of the disk from light, and then UV light L3 is irradiated. Furthermore, as shown in FIG. 4(c), the mask 8 is removed and the U
The V light L4 is irradiated onto the TjV curable resin 7 for forming a texture.

By the above method, unevenness is formed on the inner circumference of the magneto-optical disk because the UV-curable resin for texture formation is cured in two steps, and on the outer circumference, almost no unevenness is formed because it is cured in one step. As a result, a magneto-optical disk is formed in which coarse physical irregularities with a maximum height of 1 (10 to 2,500 μm) are formed on the inner circumference, and fine physical irregularities with a maximum height of 200 μm or less are formed on the outer circumference.

(G) Effects of the Invention According to the present invention, physical irregularities are formed by irradiating the photocurable resin with light at different wavelengths and irradiation amounts, which makes it possible to produce in large quantities and at low cost. A magneto-optical disk and a method for manufacturing the same are obtained. Furthermore, it is also possible to keep the flying height of the flying head constant.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing the structure of Embodiment 1 of the present invention, and FIG.
3 is a longitudinal sectional view showing the structure of Example 2 of the present invention. FIG. 4 is a process diagram showing the manufacturing process according to Example 2. 6 is a perspective view showing the structure of a flying head, FIG. 6 is a process diagram showing the manufacturing process in a conventional example, and FIG. 7 is a plan view showing the structure of unevenness in a conventional magneto-optical disk. 5'WJ ■...Transparent substrate, 2...Recording film, 3...
- Protective layer, 4.7... UV curing resin for texture formation, 5... - Magneto-optical disk body, 8... Mask. \

Claims (1)

[Scope of Claims] 1. A magneto-optical disk, the outermost layer of which is comprised of a photocurable resin layer on which fine physical irregularities are formed on the surface layer. 2. The magneto-optical disk according to claim 1, wherein the physical irregularities are rougher on the inner circumference of the surface layer of the photocurable resin layer and finer on the outer circumference than in the inner circumference. 3. Apply a photocurable resin to the surface of the substrate on which the recording film is formed, irradiate the photocurable resin with light to harden only the surface layer, and then shorten the wavelength of light and irradiate the photocurable resin. A method for producing a magneto-optical disk, which comprises curing the inner layer of the photocurable resin to form fine physical irregularities on the surface layer of the photocurable resin. 4. Apply a photocuring resin to the surface of the substrate on which the recording film is formed, and change the amount of light irradiation on the outer and inner peripheries to create physical irregularities that are rough on the inner periphery and finer on the outer periphery than the inside. 1. A method for manufacturing a magneto-optical disk, the method comprising: forming a magneto-optical disk;