JPH04195944A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To assure durability and traveling property at the time of sliding a magnetic head by forming a wear resisting protection film on a surface on the opposite side of a transparent base and carrying out a cleaning process of the surface of the wear resisting protection film. CONSTITUTION:The wear resisting protection film 7 is formed on the surface on the opposite side of a transparent base 4 and the cleaning process is carried out on the surface of the protection film for abrasion 7. Therefore, by carrying out recording while sliding the magnetic head 3 against the magneto-optical recording medium 1, distance at a recording magnetic layer 8 is made smaller and the magnetic flux being generated by the magnetic head 3 can be a small one. Furthermore, since the wear resisting protection film 7 is formed on the sliding surface with the magnetic head 3, little abrasion or damage is reduced, and since the protection film 7 has its surface cleaning processed, stuck matter on the surface is eliminated, and the damage to the magneto-optical recording medium 1 and the magnetic head 3 can be prevented. Thus, the durability and traveling property while sliding the magnetic head is secured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magneto-optical recording medium used in a magneto-optical recording method in which recording is performed by sliding a magnetic head on the magneto-optical recording medium. be.

[Summary of the invention]

The present invention provides a magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate, by forming an abrasion-resistant protective film on the surface opposite to the transparent substrate and cleaning the surface. The purpose is to prevent damage to the magneto-optical recording medium or the magnetic head even when the magnetic head is slid, and to ensure sufficient durability and runnability.

[Conventional technology]

In the magneto-optical recording method, the temperature of a part of a magnetic thin film is raised above the Curie point or temperature compensation point, and the coercive force in this part is extinguished to reverse the direction of magnetization in the direction of the externally applied recording magnetic field. The basic principle is that optical file systems, computer external storage devices, audio,
It is being put into practical use in video information recording devices and the like.

The magneto-optical recording medium used in this magneto-optical recording method has a recording magnetic layer on one main surface of a transparent substrate made of polycarbonate or the like, which has an axis of easy magnetization perpendicular to the film surface and has a large magneto-optic effect. (For example, a rare earth-transition metal alloy amorphous thin film), a reflective layer, and a dielectric layer are stacked to form the recording section, and the signal is read by irradiating laser light from the transparent substrate side. Are known.

[Invention or problem to be solved]

By the way, magneto-optical recording systems can be broadly divided into optical modulation systems and magnetic field modulation systems, and since overriding is possible, expectations for the magnetic field modulation systems are increasing.

The above magnetic field modulation method writes information signals in a magnetic thin film by reversing the applied magnetic field at high speed, and the application of the magnetic field is usually performed by a magnetic head that includes magnetic field generating means.

In this case, a magnetic head that applies a high-speed switching magnetic field can only generate a very small magnetic field due to various restrictions, and it is necessary to move the magnetic head as close to the recording magnetic layer as possible. For example, in the case of a magneto-optical disk for data recording, the distance between the magneto-optical disk surface and the magnetic head must be 0.1 or less.

When the distance between the magneto-optical disk and the magnetic head decreases in this way, it is necessary to improve the dimensional accuracy of the magneto-optical disk to suppress surface runout in order to prevent crashes of the magnetic head.

However, with magneto-optical disks made of substrates or polycarbonate, there is a limit to the suppression of surface wobbling, and it is difficult to keep the distance between the magnetic head and the magneto-optical disk constant, such as in the force surfer of an optical pickup. You have no choice but to apply servo or use a so-called flying head like a node disk.

However, especially in low-speed rotation systems of about 300 to 600 rpm, flying heads cannot be used, and complex servos are required to control the distance.

In addition, in the case of a high-speed rotation system with a rotation speed of about 3600 rpm, it is necessary to use a flying head in which the magnetic head floats via an air bearing, or to avoid the problem of crashes during start and stop.

Furthermore, even when using servo to maintain a constant distance from the disk, or when using a flying head, the distance between the magnetic head and the magneto-optical disk must be maintained. Also on the magneto-optical disk side, the recording magnetic layer must be a magnetic thin film that can only be written with a low magnetic field.

Therefore, a magneto-optical recording method may be considered in which recording is performed by sliding a magnetic head against a magneto-optical recording medium, but in this case, an important issue is how to ensure durability and runnability.

The present invention was proposed to solve this problem, and has sufficient durability even when the magnetic head is slid.
An object of the present invention is to provide a magneto-optical recording medium that can ensure running performance.

[Means to solve the problem]

In order to achieve the above object, the magneto-optical recording medium of the present invention is a magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate, in which a wear-resistant protection is provided on the surface opposite to the transparent substrate. It is characterized in that a film is formed and the surface of the wear-resistant protective film is subjected to a cleaning treatment.

[Effect]

If recording is performed without the magnetic head sliding against the magneto-optical recording medium, the distance to the recording magnetic layer will be sufficiently small, and the magnetic field generated by the magnetic head will be small. Furthermore, no special servo mechanism is required for the magnetic head, and problems such as crashes are eliminated.

However, in this case, an increase in error rate due to wear and damage to the magneto-optical recording medium becomes a problem, but in the magneto-optical recording medium of the present invention, a wear-resistant protective film is formed on the sliding surface of the magnetic head. This ensures sufficient durability against wear and damage.

Further, since the surface of the wear-resistant protective film has been subjected to a cleaning treatment, deposits on the surface are removed, and damage to the magneto-optical recording medium and the magnetic head is prevented.

〔Example〕

Embodiments to which the present invention is applied will be described in detail below with reference to the drawings.

First, FIG. 1 shows a schematic configuration of a magneto-optical recording device for recording information signals on a magneto-optical disk No. 2 of this embodiment.
1) and insert the optical pickup (2) and magnetic head (3) between them.
) are arranged facing each other, and signals are recorded while a magnetic head (3) is slid against the magneto-optical disk (1).

As shown in FIG. 2, the magneto-optical disk (1) of this embodiment used in such a recording device has a recording section (5) laminated on the -main surface of a substrate (4), and this recording section The surface of (5) is coated with ultraviolet curing resin layer (6) and wear-resistant protective film (7).
).

The substrate (4) is a disk-shaped transparent substrate with a thickness of about several liters (for example, 1,2 mm), and its material is a plastic material such as acrylic resin, polycarbonate resin, polyolefin resin, or epoxy resin. Other materials such as glass are also used.

In addition, on the surface of this substrate (4) on the side where the recording section (5) is provided, there are usually guide grooves and addresses having a depth of approximately one-fourth of the wavelength of the laser light used during reproduction. A code pit etc. (all illustrations are omitted) is provided.

The recording section (5) includes a recording magnetic layer (8), a dielectric layer (9),
(10) and a reflective layer (11), a first dielectric layer (9), a recording magnetic layer (
8), the second dielectric layer (10), and the reflective layer (11).

Among these, can oxides, nitrides, etc. be used for the first dielectric layer (9) and the second dielectric layer (10)? Nitride is more preferable because oxygen may have an adverse effect on the recording magnetic layer (8), and silicon nitride or aluminum nitride is preferable as a material that does not transmit oxygen and moisture and can sufficiently transmit the laser beam used. is suitable.

The recording magnetic layer (8) is an amorphous magnetic thin film having an easy magnetization direction perpendicular to the film surface, and has not only excellent magneto-optical properties but also a large coercive force at room temperature. , and it is desirable to have a Curie point near 200°C. Recording materials that meet these conditions include rare earth-transition metal alloy amorphous thin films, among which T
bFeC.

A non-crystalline thin film is preferred. This recording magnetic layer (8) may contain an additive element such as Cr for the purpose of improving corrosion resistance.

The reflective layer (11) is preferably composed of a film with a high reflectance that reflects 70% or more of the laser beam at the boundary with the second dielectric layer (10), and is preferably a vapor-deposited film of a non-magnetic metal. be. Further, it is desirable that this reflective layer (moon) be a good thermal conductor, and aluminum is suitable in consideration of ease of availability and ease of film formation.

Each of these layers is formed by a so-called vapor plating technique such as vapor deposition or sputtering. At this time, the thickness of each layer can be set arbitrarily, but is usually set to about several hundred to several thousand λ. It is preferable that these film thicknesses be determined not only by the optical properties of each layer alone, but also by taking into account the effects of the combination.

For example, when the thickness of the recording magnetic layer (8) is thinner than the wavelength of the laser beam, multiple interference occurs between the laser beam and the light that passes through the recording magnetic layer (8) and is reflected at the boundaries of each layer. This is because the effective optical and magneto-optical properties of the recording magnetic layer (8) vary greatly depending on the combination of thicknesses.

The ultraviolet curing resin layer (6) is provided for the purpose of flattening and protecting the surface of the recording section (5), but may be omitted depending on the case. The thickness of this ultraviolet curable resin layer (6) is about 3 to 5 μm, and acrylic ultraviolet curable resin or the like is usually used.

The above is the basic configuration of the magneto-optical disk (1),
In the magneto-optical recording medium of the present invention, in order to perform magnetic field modulation recording while sliding the magnetic head (3) on the disk surface, A wear-resistant protective film (7) is provided directly on the magnetic head (3) to suppress wear caused by sliding and ensure running performance of the magnetic head (3). Below, this wear-resistant protective film (7
) will be explained.

First, the wear-resistant protective film (7) formed on the sliding surface of the magnetic head of the magneto-optical disk (1) is basically a resin-cured film made of thermosetting resin, electron beam curing resin, ultraviolet curing resin, etc. or a resin cured film partially blended with electron beam curing resin or ultraviolet curing resin.

For example, by irradiating an electron beam-curable oligomer with an electron beam and curing it to form a wear-resistant protective film (7), a magneto-optical disk that is less likely to be damaged when a magnetic head comes into contact with it can be obtained. In this case, the molecular weight of the oligomer used is 2
000 or less is preferable.

Similarly, a strong film can be formed by blending an ultraviolet curable resin into the wear-resistant protective film (7) and curing it by irradiating it with ultraviolet rays immediately after forming the protective film (7).

Alternatively, when forming the wear-resistant protective film (7), a curing agent may be added internally to improve the film strength and increase durability. In this case, the molecular structure and type of the curing agent used are arbitrary, and it is also possible to use multiple types of curing agents. The amount of curing agent added depends on the type of curing agent used, but is usually 0.00 parts by weight per 100 parts by weight of the resin.
It is preferable to use 1 to 50 parts by weight. In addition, the curing temperature is arbitrary, and curing at room temperature is possible, or the curing speed is slow, so create a predetermined temperature environment (e.g. above the glass transition point) in a thermostatic oven and harden by placing it in that temperature for a certain period of time. It is preferable to increase the speed.

The heat curing treatment is advantageous not only in shortening the reaction time (but also in terms of removing residual solvent and moisture, and improving film hardness). It can be hardened and improve durability.

When the cured resin film is used as the abrasion-resistant protective film (7) as described above, suitable methods for forming it include a doctor blade method, a spin cord method, and the like.

For example, by placing paint uniformly on the flattening adapter between the doctor blade and the magneto-optical disk (1) and moving the doctor blade toward you, a coating film with a uniform thickness is formed. Alternatively, by attaching the magneto-optical disk (1) to the motor rotating shaft and supplying the paint onto the magneto-optical disk (1) while it is not rotating, a coating film with an even thickness can be formed. Ru. These methods not only facilitate film formation, but also ensure uniform film thickness.
Furthermore, it is possible to control surface roughness and film thickness by manipulating the solid content and viscosity of the paint.

In addition, when mass production is considered, a gravure method, a sandblast transfer method, an offset method, etc. are also suitable.

In the gravure method, for example, a magneto-optical disk (1) is mounted on the outer peripheral surface of a disk holder with the magnetic head side surface facing outward, paint is supplied from a paint nozzle between an inkneri roll and a gravure roll, and the disc holder is The paint on the surface of the gravure roll is transferred to the magnetic head side surface of the magneto-optical disk (1) by running the gravure roll while pushing it with a back roll. When transferring paint, the thickness can be controlled by the position of the back roll and the pattern depth of the gravure roll. After the paint is transferred, it is flattened and dried with a dryer to form a paint film. Note that the back roll does not necessarily have to be cylindrical, and may be configured to serve as a conveyor belt of a disc holder. Furthermore, the positions and rotations of the ink dispensing roll and the paint nozzle for supplying paint are arbitrary.

The sandblast transfer method transfers paint using a sandblast roll whose surface has been roughened by sandblasting, and the basic device configuration is the same as the gravure method described above. However, inkneri roll is not necessary,
Film thickness is controlled by the position of the back roll, peripheral speed of the sandblasting roll, and surface roughness.

The offset method has the same equipment configuration as the gravure method, except that it uses an offset roll with a flat surface, and the film thickness is controlled by the position of the back roll, the circumferential speed of the offset roll, and the distance between the offset roll and the inkness roll.

These methods are excellent in terms of uniform film thickness, ease of thickness control, reproducibility, and surface roughness, and the coating speed can be set to 100 m per minute or more, making it easy to mass-produce. It is very advantageous in this respect.

Of course, the wear-resistant protective film (7) is not limited to the above-mentioned cured film, for example, AI! , those made of wear-resistant materials such as Ni by plating, vapor deposition, sputtering, etc.
It may also be a coating of a lubricating polymeric material such as polytetrafluoroethylene or a non-woven fiber such as silk. Polytetrafluoroethylene is widely used as a solid lubricant, and methods for forming a film include directly rubbing it on the disk surface, vapor deposition, and spin-coding after dissolving it in a solvent. The non-woven fiber has a fiber diameter of 500
It is preferable that the fiber be made of fibers with a diameter of μm or less, and the type of fiber may be natural or synthetic. Furthermore, it is also possible to use an abrasive-based nonmagnetic film or a lubricant film, and it is also possible to form the film by depositing lubricant powder. In this case, as the lubricant, any known lubricant such as fatty acids and fatty acid esters can be used, and the type and composition do not matter. As the lubricating powder, powder of a substance with a small coefficient of friction such as carbon or polytetrafluoroethylene may be used, or it is preferable that the hardness of the powder is lower than that of the substrate (4). The particle size of the lubricating powder used is approximately #8 to #200,000.

Moreover, the above-mentioned wear-resistant protective film (7) does not necessarily have to be a single layer, but can also be multilayered. In this case, by selecting the type of resin and the type of additives for each layer, it becomes possible to meet various demands. Alternatively, when the wear-resistant protective film (7) is made of a metal material, the lower layer is made of a hard metal film (or a non-metal film such as ceramics may be used), and the upper layer is made of Au, Ag, etc.
It is also possible to use a soft metal film, such as Pb, to create a structure that reduces impact and wl friction.

Furthermore, a solid filler such as lubricating powder or abrasive material is added to the above-mentioned wear-resistant protective film (7) to improve running performance.

The durability may be further improved.

The type of lubricating powder and abrasive material does not matter; carphone (carbon black, graphite powder, etc.) is the lubricating powder.
or polytetrafluoroethylene powder (so-called Teflon powder), etc., and alumina, chromium oxide (so-called green), etc. are suitable as the abrasive material. It is also possible to add multiple types at the same time.

The above-mentioned solid filler is generally added internally to the wear-resistant protective film (7), and in this case, the particle size is preferably within twice the film thickness at most. It is also possible to apply the solid filler mixed with a small amount of binder or just the solid filler to the wear-resistant protection H(7) surface, in which case the maximum particle size is Protective film (7)
It must be equal to or less than the M thickness of .

Furthermore, lubricants, extreme pressure agents, coupling agents, etc., which are widely used in the field of magnetic recording media, etc., are added or applied to the wear-resistant protective film (7) to prevent damage when the magnetic head comes into contact with it. It may be possible to prevent this.

All kinds of lubricants can be used as lubricants, such as higher fatty acids such as oleic acid and fatty acid esters, and extreme pressure agents include phosphorus-based extreme pressure agents, inert-based extreme pressure agents, and halogen-based extreme pressure agents. Any conventionally known agent can be used, such as an agent, an organometallic extreme pressure agent, or a composite extreme pressure agent. As the coupling agent, various coupling agents can be used, such as a Nolan coupling agent, a titanium coupling agent, and a zylfarminate coupling agent. By using these coupling agents, the resin constituting the wear-resistant protective film (7) and the substrate, as well as the powder components such as abrasives, are chemically bonded, increasing the strength of the film and its adhesion to the substrate. Is possible.

Other products include γ-Fezes acicular magnetic powder, Co-impregnated (doped) γ-Pesos acicular magnetic powder, Co-coated γ-FetOz acicular magnetic powder, metal magnetic powder, C
It is also possible to use magnetic powder such as ry, magnetic powder, barium ferrite, etc. as the abrasive. The magnetic coating film containing these magnetic powders has been proven to be highly durable when used with magnetic tapes, etc., and due to its high magnetic permeability, it is possible to apply a sufficient magnetic field to the recording section (5) even with a small magnetic field. It's sexual.

When these magnetic powders are dispersed in the wear-resistant protective film (7), the orientation direction of the magnetic powders is non-oriented, circumferential direction (including cases where the magnetic powder is oriented obliquely to the film surface), and radial direction. (one direction within the plane), vertical direction, etc., or
Various advantages can be obtained by selecting the orientation direction.

For example, in the case of non-oriented magnetic powder, the magnetic powder is oriented in random directions even at the same position within the plane of the magneto-optical disk (1).
The magnetic influence exerted on the recording magnetic layer (8) is considered to be the same in all parts, and the influence of bit length, noise, etc. is eliminated. Even when oriented in the circumferential direction, magneto-optical disks (
1) has the same orientation in any part of the recording magnetic layer (8
), there are few factors that give local magnetic anisotropy;
There is no change in bit length, noise, etc. depending on location.

On the other hand, in the case of vertical orientation, the magnetization direction of the recording magnetic layer (8) coincides with the easy axis of magnetization of the magnetic powder, and since the magnetic permeability in this direction is high, a larger magnetic field is applied to the recording magnetic layer (8).
8), making it possible to record with a small magnetic field.

As the orientation method, any method used for magnetic recording media can be applied. For example, to achieve non-orientation, a pair of orientation magnets may be arranged in opposite directions of the magnetic poles or perpendicular to each other within the film surface of the coating film. However, an alternating current voltage may be applied to each of these orientation magnets before the coating film dries.

For circumferential orientation, both widthwise edges must be N
Using a long magnet with poles and south poles, one longitudinal end of this magnet is placed at the center of the magneto-optical disk (1), and the magnet is rotated in the circumferential direction of the disk around this one end. That's fine. When oriented in the radial direction, the N and S poles are placed on both sides in the radial direction, respectively.
It is sufficient to use a long magnet with poles and move it in parallel in the width direction of the magnet over the magneto-optical disk (1).

In the case of vertical alignment, a DC magnet may be arranged so that magnetic flux passes perpendicularly to the disk surface of the magneto-optical disk (1), and the magneto-optical disk (1) may be rotated.

In addition, in the above-mentioned abrasion-resistant protective film (a), by imparting color by selecting pigments, etc., it is possible to ensure durability and at the same time give designability and increase commercial value.

In the wear-resistant protective film (7) having the above configuration,
In order to perform good magnetic field modulation recording, it is necessary to set the film thickness to an appropriate value.

That is, the thickness of the wear-resistant protective film (7) determines the distance between the magnetic head (3) and the recording section (5). The distance between the recording magnetic layers (8) of the recording section (5) must be such that the minimum magnetic field required for recording can reach the recording magnetic layer (8) of the recording section (5). From the magnetic head (3) side, the distance must be such that the recording current can be made sufficiently small to apply the same magnetic field to the recording magnetic layer (8). for example,
In order to generate a magnetic field of ±200 Oe in the recording magnetic layer (8), the distance between the magnetic head (3) and the recording magnetic layer (8) is 0.4 mm (400 μm).
While a recording current of approximately ±IA is required, if the distance is 0.04 mm (40 μm), approximately ±IA is required.
A recording current of 0.5 A is sufficient.

As for the lower limit, it is sufficient that the film thickness is sufficient to ensure durability, and it should also be within a range that will not damage the recording section (5) even if the wear-resistant protective film (7) is slightly scratched. do it.

In view of these points, the thickness of the wear-resistant protective film (7) is preferably 0.01 to 50 μm. If the film thickness exceeds 50 μm, the strength of the magnetic field reaching the recording magnetic layer (8) will be small, and a large recording current will be required during recording. On the other hand, if the film thickness is less than 0.01 μm, it will be difficult to ensure sufficient durability, and there is a risk that the recording section (5) will be damaged by scratches or the like.

By the way, in the above-mentioned wear-resistant protective film (7), various problems will occur if there are deposits on the surface. For example, if dust with a certain degree of hardness adheres to the surface of the wear-resistant protective film (7), there is a risk of damaging the magneto-optical disk (1) or the magnetic head (3) when the magnetic head comes into contact with it. be.

Therefore, in this embodiment, the surface of the wear-resistant protective film (7) is subjected to a cleaning treatment to remove the deposits and thereby eliminate the above-mentioned disadvantages.

As a method for cleaning the surface of the wear-resistant protective film (7), physical means, chemical means, and electrical means can be considered, and any of them may be adopted. Specifically, electrostatic dust collection processing, contact dusting processing, adhesive roll processing, vacuum processing, liquid cleaning processing, clean air processing,
Examples include ultrasonic clean treatment and knife treatment.

The electrostatic dust collection process is performed by setting the magneto-optical disk (1) on the negative side electrode, arranging the positive side electrode as a dust collection electrode facing each other, and applying a high voltage to electrostatically collect the dust on the negative side. The dust on the magneto-optical disk (1) side is attracted to the dust collecting electrode. In this case, the power supply is
Either direct current or alternating current may be used, and the applied voltage is 1-10
It may be set to 00,000 kV.

Contact dusting treatment uses diameters of 0.5 to 100O10.
The dusting paper is brought into contact with a 000t contact roll, and the dust is scraped off by the dusting paper by rotating the magneto-optical disk (1). The dusting paper can be made of either woven or non-woven fabric. In addition, magneto-optical disks (
The rotation direction, dusting paper feeding speed, feeding direction, etc. of 1) are arbitrary.

Adhesive roll treatment is a method of removing dust by pressing an adhesive roll against it, and uses an adhesive roll whose surface is coated with an adhesive substance. The adhesive roll materials include natural rubber, nitrile rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber, butyl rubber, styrene rubber,
Urethane rubber, Hypalon rubber, fluororubber, etc. are optional.

In the vacuum treatment, dust is sucked out by vacuum reduction, and a vacuum duct is disposed near the wear-resistant protective film (7), and the dust is removed by evacuating the air in the duct. In this case, the vacuum pressure is 70
It does not matter whether it is preferable to be less than 0au++Hg or the shape of the duct. Moreover, this vacuum treatment is even more effective when used in combination with other methods.

Liquid cleaning treatment is a method of washing away dust by using a liquid such as alcohol, Freon, or pure water that does not attack the wear-resistant protective film, and by spraying at high pressure, using ultrasonic waves, roll transfer, etc. .

The clean air treatment is a method in which clean air from which dust has been removed to a degree of cleanliness of 100 or less is applied with pressure (a static pressure of 10 mmHg or more) and blown out from a nozzle at an arbitrary angle to blow off the dust.

The ultrasonic cleaning process involves using an ultrasonic oscillator to vibrate the air and the wear-resistant protective film (7) to float dust, which is then sucked up using a vacuum. The ultrasonic vibration is 5000) (z or higher), the vacuum pressure only needs to be lower than the surrounding atmospheric pressure, and the arrangement of the ultrasonic oscillator and the vacuum device is arbitrary.

Knifetsu treatment involves applying a knife with a certain width evenly to the wear-resistant protective film (7) of the magneto-optical disk (1), and removing dust with the knife's edge by rotating the magneto-optical disk (+). It is something to do. Here, it is preferable that the blade edge angle of the knife used is set to 1 to 150 degrees, and the rotation speed of the magneto-optical disk (1) is set to about 30 to 10,000 times/min. The direction of rotation etc. does not matter.

Next, a magneto-optical disk was actually created, its surface was cleaned, and the magnetic head was slid to perform recording, and its characteristics were evaluated.

Example 1 The recording portion of the produced magneto-optical disk had a four-layer structure, and the film thickness was as follows.

First dielectric layer: Si, N = 1000 people Recording magnetic layer: Tb-Fe-Co-Cr230 people Second dielectric layer + 5izN4 500 people Reflective layer: Af 700 people Ultraviolet curing resin layer: 3 μm The above configuration A wear-resistant protective film was formed on the ultraviolet curable resin layer of the magneto-optical disk by the following method.

Composition of paint Carbon (average particle size 200μ)...100 parts by weight Vinyl chloride-vinyl acetate copolymer...100 parts by weight Vinyl chloride-vinyl acetate-vinyl alcohol copolymer
...400 parts by weight The above composition was kneaded with a mixed solvent of methyl ethyl ketone/toluene/cyclohexanone (1:1:1) in a ball mill for 40 hours.

Next, 20 parts by weight of a thermosetting agent (trade name Coronate) and 1.5 parts by weight of an aliphatic hydrocarbon lubricant (olive oil) were added and stirred for 20 minutes.

This was applied onto the above ultraviolet curable resin layer using a transfer roll at a coating speed of 5 m/min and dried.

The thickness of the coating film after drying was 20 μm.

Next, the surface of this wear-resistant protective film was applied with a voltage of 3000V.
Electrostatic precipitate treatment was performed.

Example 2 A magneto-optical disk similar to Example 1 was prepared, and a dusting paper was brought into contact with the surface of the wear-resistant protective film. During the treatment, the dusting paper was fed at a speed of 1 min/min, and the magneto-optical disk was rotated at 1 Orpm.

Example 3 A magneto-optical disk similar to Example 1 was prepared, and an adhesive roll made of urethane rubber was brought into contact with the surface of the wear-resistant protective film. The diameter of the adhesive roll used was 10 mm, and the rotation speed of the magneto-optical disk during contact was 10 rpm.

Example 4 A magneto-optical disk similar to that in Example 1 was prepared, and the surface of the wear-resistant protective film was vacuum-treated at a static pressure of 500 mmHg.

Example 5 A magneto-optical disk similar to Example 1 was prepared, and ethyl alcohol was sprayed at high pressure onto the surface of the wear-resistant protective film.
Washed for seconds.

Example 6 A magneto-optical disk similar to that in Example 1 was prepared, placed in a container filled with ethyl alcohol, and subjected to ultrasonic cleaning.

Example 7 A magneto-optical disk similar to Example 1 was prepared, and air with a cleanliness level of class 500 was applied to the surface of the wear-resistant protective film at a static pressure of 5.
It was sprayed with 00 guaHg and treated with clean air.

Example 8 A magneto-optical disk similar to that of Example 1 was prepared, and the surface of the wear-resistant protective film was vacuum-vacuumed while applying ultrasonic vibrations with an ultrasonic oscillator, and subjected to ultrasonic cleaning treatment. The feeding speed of the magneto-optical disk during processing was 1 m/min.

Example 9 A magneto-optical disk similar to that of Example 1 was prepared, and a knife with a cutting edge angle of 60° was applied to the surface of the wear-resistant protective film, and the magneto-optical disk was rotated 10 times for knife treatment.

All of the magneto-optical disks obtained as described above had significantly less deposits on the surface, and almost no scratches were observed even after 10' passes.

〔Effect of the invention〕

As is clear from the above explanation, in the magneto-optical recording medium of the present invention, since a wear-resistant protective film is formed on the surface, it is possible to significantly suppress wear caused by sliding of the magnetic head. Therefore, it is possible to ensure durability. Furthermore, since the surface of the wear-resistant protective film is cleaned to remove surface deposits, it is possible to eliminate damage to the magnetic head and magneto-optical recording medium caused by the surface deposits. .

On the other hand, if the magneto-optical recording medium of the present invention is used, the distance between the magnetic head and the recording magnetic layer can be stably maintained at a small value without the need for complicated servos, etc. by sliding the magnetic head against the magneto-optical recording medium. I can do something. Therefore, a magnetic field modulation magnetic head can be used even if the generated magnetic field is small, and if it has the ability to generate a large magnetic field, it is possible to reduce the applied current and save power. be. Furthermore, it becomes possible to ensure the frequency characteristics of the magnetic head up to a high frequency range, and it becomes possible to achieve a high transfer rate and high density.

In addition, when viewed from the magneto-optical recording medium side, it is no longer necessary to have a recording magnetic layer with high magnetic field sensitivity, and if the recording magnetic layer is a film that can be recorded in a low magnetic field, it is necessary to have a wide margin against the magnetic field. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining a sliding type magneto-optical recording system to which the magneto-optical recording medium of the present invention is applied. FIG. 2 is an enlarged sectional view of a main part showing an example of the configuration of a magneto-optical recording medium to which the present invention is applied. l...Magneto-optical disk 2...Optical pickup 3...Magnetic head 5...Recording section 7...Wear-resistant protective film

Claims (1)

[Claims] A magneto-optical recording medium in which a recording magnetic layer is formed on a transparent substrate, wherein a wear-resistant protective film is formed on a surface opposite to the transparent substrate, and the wear-resistant protective film A magneto-optical recording medium characterized in that the surface of the film has been subjected to a cleaning treatment.