JP3367989B2 - Magneto-optical recording medium and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium capable of recording, reproducing and erasing information by a light beam, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, an optical memory such as an optical disk has been actively developed and commercialized as a large-capacity information recording means, and in particular, a magneto-optical recording medium capable of erasing and rewriting information has attracted attention.

However, in the conventional magneto-optical recording medium, when the recorded information is rewritten, two steps such as erasing the recorded old information and recording the new information are necessary, and the data transfer rate is required. There was a problem in terms of speeding up. Then, in order to solve such a problem, when rewriting information, a magnetic field modulation method that does not require erasing old information, that is, while continuously irradiating a magneto-optical recording medium with laser light of a constant intensity, A method of recording by modulating with an information signal has been proposed.

When the above magnetic field modulation method is used for recording information on the magneto-optical disk, in order to increase the switching speed in the direction of the external magnetic field and improve the transfer speed, the magnetic head has a low inductance. Although it is necessary, the magnetic field sensitivity is reduced accordingly, and therefore it is preferable that the magnetic head be as close to the magneto-optical recording layer as possible (see FIG. 8).

However, in this case, at the start of rotation of the disk,
When the magnetic head is stopped, the magnetic head slides on the protective layer provided on the magneto-optical recording layer, so that the magnetic head and the protective layer cause electrostatic attraction, which makes it difficult to drive the magnetic head and the magneto-optical disk. was there.

In order to solve such a problem, the applicant of the present invention discloses in JP-A-4-64939 that a conductive inorganic filler such as tin oxide is dispersed in the protective layer to reduce the surface electric resistance of the protective layer. Therefore, it is proposed to prevent electrostatic attraction of the magnetic head and the protective layer.

However, although such a structure is effective in preventing the magnetic head and the protective layer from adsorbing, the recording sensitivity of the magneto-optical disk tends to decrease, and the shape of the recording pit becomes non-uniform, so that the reproduction signal of the recorded information is not reproduced. There was a problem that C / N was lowered.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to prevent electrostatic attraction between a magnetic head and a protective layer and to reduce recording sensitivity and C
An object of the present invention is to provide a magneto-optical recording medium capable of suppressing a decrease in / N ratio.

Another object of the present invention is to provide a method of manufacturing a magneto-optical recording medium which can prevent electrostatic attraction between a magnetic head and a protective layer, and have a very small reduction in recording sensitivity and C / N ratio. To aim.

As a result of studying the above-mentioned problems with respect to such an object, the present inventors have found that the decrease in recording sensitivity and the decrease in C / N ratio are dispersed in order to impart conductivity to the protective layer. The inventors have found that this is due to non-uniform temperature diffusion of the protective layer due to the high thermal conductivity of the inorganic filler, and have completed the present invention.

[0011]

That is, a magneto-optical recording medium of the present invention has a magneto-optical recording layer and a resin protective layer on a substrate,
In a magneto-optical recording medium for recording information by applying a magnetic field to the recording layer from the protective layer side and irradiating a light beam to the recording layer through the substrate, The protective layer has a first surface on the side facing the magnetic field generating means and a second surface on the side facing the recording layer, and the first surface of the protective layer is 1 × 10 ¹⁰ Ω / □ or less. And the second surface of the protective layer has a thermal conductivity of 10 W / mK
It is characterized by the following.

[0012]

[0013]

The method of manufacturing the magneto-optical recording medium of the present invention comprises:
A magneto-optical recording layer and a resin protective layer are provided on a substrate, and a magnetic field is applied to the recording layer from the protective layer side by a magnetic field generating means, and a light beam is applied to the recording layer through the substrate. In the method of manufacturing a magneto-optical recording medium for recording information by using the above method, at least one surface has a surface resistivity of 1 × 10 ¹⁰
A resin sheet of Ω / □ or less is adhered to the magneto-optical recording layer via an adhesive layer having a thermal conductivity of 10 W / m · K or less so that the surface faces the magnetic field generating means, The method further comprises the step of forming a protective layer on the magneto-optical recording layer.

According to the present invention, a region provided on the magneto-optical recording layer side of the resin protective layer and having a thermal conductivity of 10 W / m · K or less serves as a thermal barrier for the magneto-optical recording layer, and thus the resin protective layer is protected from heat. The effect of increasing the temperature diffusivity of the resin protective layer or imparting non-uniform temperature diffusivity to recording / reproduction due to imparting conductivity can be mitigated.

Next, the present invention will be described in detail with reference to the drawings.

In the present invention, for example, as shown in FIG.
1) A magneto-optical recording layer (12) and a protective layer (13) are provided in this order on the substrate, and a magnetic field is applied to the recording layer from the protective layer side by a magnetic field generating means (14) and the substrate is formed. The present invention relates to a magneto-optical recording medium used in a method of recording information by irradiating a light beam (15) to the recording layer through a magnetic recording medium, the protective layer being opposed to the magnetic field generating means of the protective layer. The first surface of the protective layer is 1 × 10 ¹⁰ when the first surface is the surface facing the recording layer and the second surface is the surface facing the recording layer.
The surface resistivity of the protective layer is Ω / □ or less, and the thermal conductivity of the protective layer from the second surface to the first surface is 10 W / m · K or less, preferably 5 W / m · K or less, and particularly preferably. Is 1W
By using a protective layer having a region of / m · K or less, it is possible to prevent electrostatic attraction with the protective layer of the magnetic head, and to suppress lowering of recording sensitivity and lowering of C / N ratio.

FIG. 2 is a schematic sectional view showing an embodiment of the magneto-optical recording medium according to the present invention.
1) an inorganic dielectric layer (2) as a magneto-optical recording layer (12)
1), a laminated film of a magnetic layer (22) and an inorganic dielectric layer (23) is formed, and a first protective layer (24) is provided as a resin protective layer (13) on the magneto-optical recording layer (12). ) And the second
The protective layer (25) has a laminated film formed thereon.
The second protective layer is made of a resin composition containing conductive particles, whereby the surface of the second protective layer on the side facing the magnetic head (14) has a surface resistivity of 1 × 10 ¹⁰ Ω.
/ □ or less, and the first protective layer is made of a resin composition having a thermal conductivity of 10 W / m · K or less.

In the present embodiment, as the conductive particles contained in the second protective layer, the surface resistivity of the surface of the second protective layer facing the magnetic head is set to a predetermined value. Inorganic particles or organic particles can be used as long as they can be used. Examples of the inorganic particles include C
metal particles such as u, Ni, Al, etc. or conductive ceramic particles,
Specifically, TiO, TiO ₂ , ZnO, K ₂ O.TiO
Sb on ceramics such as ₂ , 9Al ₂ O ₂ · 2B ₂ O ₃
Ceramic particles or SnO which has been subjected to a conductive treatment by doping with a different element such as Al and then reducing or firing, or by depositing a conductive substance, such as Al, Ni, Sb, etc. on the surface.
₂ and so on can be used. Further, among the above-mentioned conductive ceramic particles, the one using the ceramic particles containing Ti can impart excellent conductivity to the protective layer and reduce the change in conductivity of the protective layer with time. It is possible and preferable.

The inorganic particles used in the present invention include:
It is preferable to use the above ceramics. That is, the specific gravity of the conductive ceramic particles is smaller than that of the metal particles, so that the conductive ceramic particles have good dispersibility in the second protective layer and rarely cause undesirable temperature diffusion unevenness in the second protective layer. However, when the inorganic particles are used, the thermal conductivity of the inorganic particles is higher than that of the organic particles.
It is preferable that the thickness of the protective layer is 1 μm or more, particularly 1.5 μm or more, and further 2 μm or more to further improve the barrier effect of the first protective layer against heat transfer from the magneto-optical recording layer to the second protective layer.

When inorganic particles are used, the surface resistivity of the surface of the second protective layer opposite to the magnetic head is 1 × 10 ³ to 1 × 10 ¹⁰ Ω / □, particularly 1 ×
Within the range of 10 ⁷ to 1 × 10 ¹⁰ Ω / □, electrostatic attraction to the surface of the second protective layer of the magnetic head can be effectively prevented, and the sensitivity and C / N ratio of the magneto-optical recording medium are lowered. This is preferable because it can suppress an increase in the temperature diffusivity of the second protective layer, which causes

The content of the inorganic particles in the second protective layer is such that the surface resistivity of the second protective layer is 1 × 10 ¹⁰ Ω.
It may be contained so that it becomes less than or equal to □, but the weight ratio is 40
% Or less, particularly 20 wt% or less, and further preferably 15 wt% or less.

That is, when the amount of the inorganic filler added to the protective layer is within the above range, the strength of the protective layer is lowered, the protective layer is scratched when it comes into contact with the magnetic head, and the filler is aggregated and the protection associated therewith is generated. It is possible to avoid the problem that protrusions composed of aggregates of filler are formed on the layer surface.

Further, as the particle size of the inorganic particles,
When the average particle diameter is 0.1 to 5 μm, and particularly 0.5 to 3 μm, the aggregation of particles in the second protective layer and the uneven temperature diffusion of the second protective layer due to the aggregation do not occur, which is preferable.

When the above-mentioned conductive ceramic particles are used as the conductive particles, it is preferable to use acicular or scaly particles having an aspect ratio of 5 or more, particularly 10 or more and 50 or less.

The aspect ratio is the ratio b of the length b of the particles in the longitudinal direction to the length a in the lateral direction thereof.
It is represented by / a.

That is, when needle-shaped or scale-shaped conductive ceramic particles having an aspect ratio of 5 or more are used, high conductivity is obtained even when the amount added to the second protective layer is small, for example, 15% by weight or less. Since it can be imparted, it is possible to suppress an increase in the temperature diffusivity of the second protective layer, which causes a decrease in the recording sensitivity and C / N ratio of the magneto-optical recording medium, and the thickness of the first protective layer is also The resin protective layer (12) can be made thinner than when using metal particles or ordinary conductive ceramic particles.
The overall film thickness can be reduced, and the magnetic head (14) can be brought closer to the magneto-optical recording layer (12). Further, since the amount of particles added to the second protective layer can be suppressed, it is possible to prevent the mechanical strength of the second protective layer, such as head crush resistance, from decreasing.

Further, it is possible to suppress aggregation of particles.
When the above-mentioned acicular or scale-like particles are used, those having an average length in the longitudinal direction of 0.5 to 5 μm, particularly 1 to 4 μm are preferably used in consideration of their dispersibility.
Next, in the present embodiment, as the organic conductive particles,
Particles composed of a conductive polymer compound or a charge transfer complex can be used, and examples of the conductive polymer compound include a polymer having para-phenylene or a derivative thereof such as thiophene, furan, or a pyrrole-based hetero 5-membered ring as a monomer unit. A polymer having as a monomer unit can be used, and further, a conductive polymer obtained by complexing polypyrrole and polyanion at the molecular level can also be used. Further, as the charge transfer complex, for example, a tetracene compound represented by the following formula (I), which has a small change in electric resistance even under a high temperature and high humidity environment and has excellent dispersibility in a resin composition, can be used. It is preferably used.

[0029]

[Outer 1]

In the present embodiment, the organic conductive particles such as the conductive polymer compound and the charge transfer complex described above almost always change the temperature diffusivity of the second protective layer depending on the addition amount thereof. Since it is not present, it is preferable to add the organic conductive particles so that the surface resistivity of the surface of the second protective layer on the magnetic head side is 1 × 10 ¹⁰ Ω / □ or less. In addition, when the above-mentioned organic conductive particles alone cannot impart a predetermined conductivity to the second protective layer, the above-mentioned inorganic conductive particles may be used in combination.
In order to prevent the degree of temperature diffusion of the protective layer from increasing, it is preferable to minimize the addition amount of inorganic particles, and if the predetermined surface resistivity can be obtained with only organic conductive particles, it is preferable to use inorganic particles. It is not necessary to add system particles.

Next, various synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene and polybutylene are used as the resin component of the second protective layer in the present embodiment, which serves as the matrix of the inorganic and / or organic conductive particles. Although terephthalate or natural resin can be used, a cross-linking polymer compound capable of forming a resin layer having excellent abrasion resistance particularly when sliding with a magnetic head and low moisture permeability, specifically JIS- A polymer compound that gives a resin layer having a water vapor transmission rate of 100 g / m ² · 24 hr or less based on the regulation of Z-0208, and a polymer that gives a lubricating surface to the resin layer can be preferably used.

As the above-mentioned cross-linkable polymer compound, those cross-linked by heat or radiation (light, electron beam, etc.) are used, and photo-curable resin is preferably used because it is particularly excellent in productivity. And as the photocurable resin compound,
For example, a product obtained by polymerizing an acrylate-based resin composition that can effectively prevent the permeation of oxygen and water into the magneto-optical recording layer is used. For example, the ultraviolet-curable acrylate-based resin composition is usually (A) It is composed of a mixed composition of a polymer component, (B) a reactive diluent component, and (C) a photopolymerization initiator component. Examples of the (A) component include polyol polyacrylate, polyester acrylate, urethane acrylate and epoxy acrylate. To be An acrylic ester of a polyhydric alcohol is used as the component (B). As the component (C), any known photopolymerization initiator can be used, but one having good storage stability after blending is preferable. For example, benzoin alkyl ether type,
Examples thereof include acetophenone type, propiophenone type, anthraquinone type, thioxanthone type and the like. These may be used alone or as a mixture of two or more kinds at any ratio.

Examples of the polymer compound that provides the moisture-proof resin layer include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymer, and the like. Of these, polyvinylidene chloride and vinyl chloride-vinylidene chloride copolymers are particularly preferable because of their low moisture permeability. The composition is not limited to the above composition as long as it has a water vapor permeability equal to or lower than that of the composition.

Further, as the polymer compound which gives the lubricous resin layer, those obtained by polymerizing a lubricating monomer such as fluorinated acrylate and siliconized acrylate are preferably used. Among the lubricating monomers, an ultraviolet curable resin composition having an acrylic group or a methacrylic group is preferably used. In addition, a fluorinated acrylate oligomer or a siliconized acrylate oligomer (weight average molecular weight 200 to 5000) is added to an ultraviolet curable resin composition such as urethane acrylate, epoxy acrylate, polyester acrylate, and polyether acrylate, and the amount of the fluorinated acrylate oligomer or the siliconized acrylate oligomer is 5 to the ultraviolet curable resin. You may mix | blend-about 20 weight%. Fluorine-based polymers are also preferably used. Further, a liquid fluorine-based lubricant may be blended with the above ultraviolet curable resin composition. Further, a radiation curable resin composition which is cured by an electron beam, light or the like, and a resin composition in which a lubricating filler is mixed in an amount of 2 to 30% by weight, preferably 5 to 20% by weight is also suitably used.

As the lubricating filler, graphite,
Inorganic fillers such as molybdenum disulfide and 60,000 crystal BN, and organic fillers such as silicon resin and fluorine resin can be mentioned. The particle size of the lubricating filler is 0.1 to 20 μm,
It is particularly preferably 0.5 to 5 μm.

Next, as the resin used for the first protective layer in the present embodiment, the thermal conductivity of the first protective layer is 10 W / m.
The various resins described above can be used as long as they can be K or less, preferably 5 W / mK or less, and particularly preferably 1 W / mK or less. For example, the curable polymer described above. Compounds and the like are preferably used.

In the present embodiment, the thickness of the first protective layer depends on the thermal characteristics of the conductive particles added to the second protective layer to record / reproduce information on / from the magneto-optical recording layer. Is preferably set to such a thickness as to function as a heat insulating layer so as not to deteriorate. For example, 0.5 μm or more, particularly 1.0 μm or more, and further 2 μm or more
The function of the protective layer as the heat insulating layer can be made more reliable.

Next, as a method of forming the resin protective layer of the magneto-optical recording medium of the present embodiment, the first protective layer and the second protective layer can be formed from the liquid resin composition or the liquid resin precursor in the first The protective layer material is formed on the magneto-optical recording layer (12) by a well-known film forming method such as spin coating or dipping, and the coating film is dried and solidified or cured by a predetermined method, for example, light irradiation, or The second protective layer material containing the conductive particles is formed by the above-mentioned film forming method without performing these treatments, and the second protective layer or the first protective layer and the second protective layer are cured. Alternatively, it can be formed by drying and solidifying.

Further, the second protective layer is formed in a sheet shape in advance, and the first protective layer functions as an adhesive layer so that the second protective layer is formed on the magneto-optical recording layer (12) via the first protective layer. May be fixed.

This method is a method of solidifying or curing the coating film of the protective layer material on the magneto-optical recording layer, in which stress is applied to the substrate due to shrinkage accompanying the solidification or curing of the coating film.
As a result, the problem that the magneto-optical recording medium is easily warped can be solved, and when the protective layer is formed on the magneto-optical recording layer by wet coating, the thickness of the protective layer may differ due to uneven coating. Is a preferable method because it is possible to avoid such a problem by using a resin layer which is molded in a sheet shape in advance.

Further, since the resin sheet can be easily formed into a uniform one even if it has a relatively thin film thickness (for example, 2 μm), it is a preferable protective layer for bringing the magnetic head and the magneto-optical recording layer close to each other. This method is suitable for thinning.

When the first protective layer functions as an adhesive layer for fixing the sheet-shaped second protective layer on the magneto-optical recording layer, other than the resin composition described above as a material for the first protective layer. Materials commonly used as adhesives and adhesives,
For example, an adhesive resin containing acrylic acid, acrylic ester, maleic acid or the like as a main constituent monomer (specifically, ethylene-acrylic acid copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene -Methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, etc.) and rubber-based adhesives / adhesives having a thermal conductivity of 10 W / mK or less. Can be preferably used. Here, the rubber-based adhesive / adhesive includes, for example, a rubber component having a diene bond as a rubber component and holding tack in the presence of a tackifier (tackifier) component, Examples of such a rubber component include a block-shaped thermoplastic elastomer. In the magneto-optical recording medium of the present embodiment, when the first protective layer is formed of an adhesive containing the block-shaped plastic elastomer, the viscoelastic behavior of the adhesive causes the inside of the magneto-optical recording medium to be changed. This is preferable because the stress can be relaxed with time and peeling of the magneto-optical recording layer from the substrate can be suppressed even under high temperature and high humidity conditions.

Examples of the block-shaped thermoplastic elastomer include AB, ABAA and BAAB.
(However, A is a polystyrene polymer block, B is a polymer block consisting of polybutadiene, polyisoprene, or ethylene butylene copolymer), and one or two or more mixtures of block-like plastic elastomers, In addition to other synthetic rubbers, polyolefins, and polyolefin-based copolymers.

As the tackifier component used here, those composed of rosin-based resins, terpene-based resins, petroleum resins such as aliphatic, alicyclic and aromatic resins are used. Further, the method for curing the liquid pressure-sensitive adhesive composition includes a method of blending a conventionally known radical polymerization initiator and heating, a method of blending a photopolymerization initiator and irradiating with UV light,
A method of irradiating with an electron beam can be applied.

In the present embodiment, when a resin sheet formed in advance as a sheet is used as the second protective layer and a resin protective layer is formed using an adhesive layer as the first protective layer, By forming the protective pressure-sensitive adhesive sheet integrally including the second protective layer and the first protective layer by such a method, the resin protective layer can be formed on the magneto-optical recording layer very easily. That is, as shown in FIG. 4 (a), a first supporting film (41) such as a polyester film is coated with a predetermined method, for example, a material for the second protective layer to a predetermined thickness, and then heated or irradiated with ultraviolet rays. Then, the second protective layer (25) is formed by being cured by irradiation with an electron beam or the like.

On the other hand, an adhesive layer (24) serving as a first protective layer is formed on the second support film (42), and then the first support film and the second support film are attached to the second protection layer. (25) and the pressure sensitive adhesive (24) are laminated so as to be in contact with each other to form a protective pressure sensitive adhesive sheet 43.

The method of forming a resin protective layer on the magneto-optical recording layer using this protective adhesive sheet 43 is as follows.
As shown in (a), the second support film (42) was peeled off from the protective pressure-sensitive adhesive sheet, and then the magneto-optical recording layer (12).
Pasting on top (FIG. 5 (b)) Finally, peeling off the first support film 41 completes (FIG. 5 (c)).

As another method for producing the protective pressure-sensitive adhesive sheet,
The pressure-sensitive adhesive layer serving as the first protective layer may be directly applied onto the resin sheet serving as the second protective layer formed in advance in the form of a sheet.

In the present embodiment, the thermal conductivity of the second protective layer is 10 W / mK or less, and the surface resistivity of one surface of the second protective layer is 1 × 10 ¹⁰ Ω / □ or less. If so, the first protective layer can be omitted as shown in FIG.
The process for forming the resin protective layer can be further simplified.

As a method of supporting the above two physical properties on the second protective layer, for example, the second protective layer is composed of the above-mentioned conductive polymer compound or a polymer in which a charge transfer complex is dispersed in the polymer. In particular, polypyrrole represented by the following formula (II) and the following formula (II)
0.3 to 2 wt% of the tetracene derivative represented by the general formula (I) in a polymer obtained by complexing the phenoxy resin-based polyanion represented by I) as shown in the following formula (IV) or a polymer such as a polycarbonate resin. , Especially 1-1.
A polymer in which 5 wt% is dispersed is a preferable material for the second protective layer.

When the conductive polymer compound or the polymer in which the charge transfer complex is dispersed is used as the second protective layer, a resin precursor (prepolymer or the like) constituting the second protective layer on the magneto-optical recording layer is used. ) Or a solution of the polymer by a spin coating method or a dipping method, and then cross-linked or dried by a solvent. It can also be formed by fixing the polymer formed in the form of a sheet beforehand on the magneto-optical recording layer via the above-mentioned adhesive layer. Further, the above-mentioned protective pressure-sensitive adhesive sheet may be formed by using the polymer formed into a sheet, and the resin protective layer may be formed using the polymer. In this case, the material used for the adhesive layer has a thermal conductivity of 1
It is preferably 0 W / m · K or less, but the thickness of the adhesive layer is not particularly limited as long as it is a thickness that functions as an adhesive layer.

[0052]

[Outside 2]

In the present invention, the thickness of the resin protective layer is preferably 3 to 15 μm, more preferably 5 to 10 μm. If it is less than 3 μm, it is not preferable from the viewpoint of preventing scratches on the surface, and if it exceeds 15 μm, the distance between the magnetic head slider and the magnetic recording layer becomes large, low magnetic field recording cannot be performed, and the power consumption of the drive is also reduced. I can't.

Further, in the structure of the magneto-optical recording medium to which the present invention can be applied, there is no limitation on the structure other than the resin protective layer (13), and a known structure such as an inorganic dielectric layer on a substrate,
A structure in which a magneto-optical recording layer composed of a laminated film of a magnetic layer and an inorganic dielectric layer is laminated, and further Al, Ti
It can be applied to all media such as a structure provided with a metal thin film such as.

Further, regarding each of the individual elements, the substrate may be a transparent substrate such as glass, polycarbonate resin or acrylic resin, and the inorganic dielectric film may be ZnS or S.
iO ₂ , AlN, Si ₃ N ₄ , Al ₂ O ₃ , In ₂ O ₃
And the like. Further, as the magnetic layer, Tb
FeCo, TbFeGd, NdFeCo, NdDyFe
A typical example is a magnetic film made of an alloy of a rare earth element such as Co and a transition metal element. These inorganic dielectric films,
The magnetic layer, the metal thin film and the like are formed by a physical film forming method such as a sputtering method.

In the present invention, the surface resistivity of the resin protective layer is measured according to JIS K6911, 5 and 13. That is, the surface electrode is placed on a test piece, and the resistance after charging for 1 minute is measured with a super-insulator using DC 100V to 1000V.

[0057]

[Outside 3] D: Inner diameter of surface annular electrode d: Outer diameter of surface annular electrode R _S : Surface resistance (MΩ)

The thermal conductivity of the resin protective layer is JIS-A-
According to 1412, the temperature of the sample is increased (σT) when the sample is put in a sample container incorporating a heater and a direct current of current I and voltage V is passed through the heater for t seconds.
To measure. Next, the heat capacity (C) is calculated by the following formula. C = (I · V · t) / σT ... Next, the thermal conductivity (λ) is calculated by the following formula. λ = (C · σT) / A (dt / dl) (where A is the cross-sectional area of the sample and dt / dl is the temperature gradient)

[0059]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Example 1-01) First, a urethane acrylate-based UV curable resin composition having the following composition was prepared. Urethane acrylate oligomer 18 wt%, dicyclopentadiene acrylate 65 wt%, trimethylol propane triacrylate 12 wt%, photoinitiator 5 wt% (trade name: Irgacure 184; Japan Chibagai formic chromatography Co.)

Next, the above resin composition was added with an average particle size of 0.5.
After dispersing 20 μm of SnO ₂ of μm, the resin composition was applied on the first supporting film as shown in FIG. 4A, and then UV lamp (233 W / cm ² on irradiation surface, wavelength 365 nm). Was irradiated for 7 seconds to form a first protective layer having a thickness of 6 μm.

Next, as shown in FIG. 4 (b), a polystyrene-polybutadiene block copolymer (trade name: Califlex, TR1107; manufactured by Shell Chemical Co., Ltd.) 100 is formed on the second support film. Parts by weight, modified wood rosin 5
0 part by weight and 1 part by weight of a stabilizer are mixed to obtain a thermal conductivity of 0.
A 2N / mK rubber adhesive is applied to a thickness of 2 μm to form a second protective layer, and then a first protective layer is formed as shown in FIG. 4 (c).
The first and second support films were laminated so that the protective layer and the second protective layer were in contact with each other to prepare a protective pressure-sensitive adhesive sheet.

On the other hand, a polycarbonate disk substrate having a pregroup and prepits (diameter 86 mm
φ, thickness 1.2 mm) by sputtering method
1000 Å thick SiN film, 200 Å thick amorphous Tb
A magneto-optical recording layer composed of a laminated film of a FeCoCr magnetic layer and a SiN film having a thickness of 400Å and an Al-Cr film having a thickness of 600Å were formed thereon.

Next, as shown in FIGS. 5A to 5C, the second supporting film of the protective pressure-sensitive adhesive sheet is peeled off from the first protective layer, and Al-Cr is formed on the Al-Cr film prepared above. After laminating and pressing so that the film and the first protective layer are in contact with each other, the first supporting film is peeled off, and a magneto-optical disk having a resin protective layer including a first protective layer and a second protective layer is prepared. did.

Example 1-02 In the same manner as in Example 1-01 except that the content of SnO ₂ in the second protective layer was changed to 25% by weight in Example 1-01. Made a disc.

Comparative Example 1-01 First, an acrylate-based UV curable resin composition having the following composition was prepared.・ Urethane acrylate oligomer 18wt% ・ Dicyclopentadiene diacrylate 65wt% ・ Trimethylolpropane triacrylate 12wt
% ・ Photopolymerization initiator (trade name: Irgacure 184; manufactured by Nippon Ciba-Geigy Co., Ltd.) 5 wt%

Next, 50% by weight of Sb-coated TiO ₂ particles having an average particle size of 1.5 μm was added to the above ultraviolet curable resin composition.
Dispersed.

Further, a magneto-optical recording layer and an Al--Cr film were sequentially laminated on the optical disk substrate in the same manner as in Example 1-01.

Next, as shown in FIG. 6, the ultraviolet curable resin composition was applied onto the substrate by spin coating so as to cover the outer Al-Cr thin film and the magneto-optical recording layer, and the film thickness was 8 μm.
After forming the resin layer of UV lamp (233mW on the irradiation surface
/ Cm, wavelength 365 nm) for 7 seconds to cure the resin and form a resin protective layer to obtain a magneto-optical disk.

(Comparative Example 1-02) Light was emitted in the same manner as in Comparative Example 1-01 except that the content of the conductive TiO ₂ particles was 40 wt% and the film thickness was 6 μm in Comparative Example 1-01. A magnetic disk was produced.

(Comparative Example 1-03) In the above-mentioned Example 1-01, SnO ₂ in the second protective layer was formed into TiO ₂ particles having an average particle size of 1.5 μm and coated with Sb. A magneto-optical disk was prepared in the same manner as in Example 1-01 except that the amount was 10 wt%.

(Comparative Example 1-04) A magneto-optical disk was prepared in the same manner as in Comparative Example 1-01 except that 20 wt% of SnO ₂ was contained as the conductive particles in Comparative Example 1-01.

With respect to the magneto-optical disk thus obtained, the following physical properties and characteristics were measured or evaluated. The results are shown in Table 101. Surface resistivity of the second protective layer of the magneto-optical disk Electrostatic voltage recording / reproducing characteristics of the second protective layer of the magneto-optical disk (noise level and C / N ratio) Head crush test under low humidity environment Under high temperature and high humidity environment Mechanical shape characteristics (tilt angle) of the disc before and after being left to stand. The above-mentioned measurement and evaluation were carried out as follows.

The surface resistivity super-insulator (trade name: SM-8205; manufactured by Toa Denpa Kogyo Co., Ltd.) of the second protective layer of the magneto-optical disk and the surface resistance measuring electrode thereof were used for the above-mentioned JIS- The measurement was performed with an applied voltage of 100 to 1000 V according to the regulations.

The magneto-optical disk prepared in Example or Comparative Example was mounted on a magneto-optical disk recording / reproducing device (manufactured by Canon) equipped with an electrostatic voltage floating magnetic head of the second protective layer of the magneto-optical disk, and the disk was prepared. Was rotated at 3000 rpm, and the magnetic head was levitated on the resin protective layer for 10 seconds (flying amount 1.6 μm) as shown in FIG. 1, and the electrostatic voltage on the surface of the resin protective layer was measured by an electrostatic voltage measuring device ( Product name: Statiron M-1000; manufactured by Shishido Denki Co., Ltd.
Was measured using.

Recording / reproducing characteristics As shown in FIG. 1, a magneto-optical disk recording / reproducing inspection apparatus (commercial name, LN52A; Shibasoku Co., Ltd.) in which a floating magnetic head is arranged on the resin protective layer side of each magneto-optical disk The recording noise of the magneto-optical disk was measured by recording the information and reproducing the information.
However, the recording and reproducing conditions were as follows.

Rotation speed 2400 rpm, magnetic field strength 2000
e, frequency 6 MHz, recording power 10 mW, reproducing power 1.0 mW recording / reproducing light wavelength 830 nm, head crush test, 30 ° C., 30% Rh under low humidity environment, the magneto-optical disks of Examples and Comparative Examples were rotated at 3000 rpm. Sometimes, the gap between the magnetic head slider and the protective layer is 1.6 μm
Using a magneto-optical recording / reproducing apparatus (manufactured by Canon Inc.) adjusted so that the medium is rotated at 3000 rpm for 3 seconds and then stopped for 3 seconds, a series of operations is repeated C
It was observed whether or not charge adsorption occurred on the resin protective layer of the head when the SS test was performed 100,000 times.

Mechanical Shape Characteristics (Tilt Angle) Immediately after making each magneto-optical disk and at 80 ° C. and 90 °
The warp (tilt angle) of the disc after being left for 2000 hours under high temperature and high humidity conditions of% RH was measured using a tilt angle measuring device (trade name: LM-100; manufactured by Ono Sokki Co., Ltd.). .

[0079]

[Table 1]

(Example 2-01) In Example 1-01, the TiO ₂ particles obtained by coating the surface with antimony having an aspect ratio of 5 and an average length in the longitudinal direction of 1.5 μm as conductive particles were prepared. (A) 10 parts by weight (b) 20 parts by weight (c) 30 with respect to the ultraviolet curable resin composition
Three types of magneto-optical disks of Examples 2-01 (a) to (c) were prepared in the same manner as in Example 1-01 except that the weight part was added.

(Examples 2-02 to 2-08) Example 2-
The conductive particles in the second protective layer in No. 01 are shown in Table 201 below.
A magneto-optical disk was prepared in the same manner as in Example 2-01, except that the magneto-optical disk was changed as shown in FIG.

[0082]

[Table 2]

(Example 2-09) A magneto-optical recording layer and Al-C were formed on a disk substrate in the same manner as in Example 1-01.
r films were sequentially laminated.

Then, the above-mentioned Example 1 was formed on the Al--Cr film.
The UV curable resin composition prepared in No. 01 was applied by the spin coating method, and then UV lamp (on the irradiation surface, 233 mW
/ Cm ² , wavelength 365 nm) for 7 seconds to cure the resin to form a first protective layer having a thickness of 6 μm and a thermal conductivity of 0.1 to 0.3 mW.

Next, 10 parts by weight of (a) Sb-coated TiO ₂ particles (aspect ratio = 15, average length in the longitudinal direction of 2 μm) were added to the ultraviolet curable resin composition used for forming the first protective layer, ( After b) 20 parts by weight and (c) 30 parts by weight are applied onto the first protective layer by spin coating, UV is applied.
It was irradiated with a lamp to be cured, and a second protective layer having a thickness of 8 μm was formed to obtain three types of magneto-optical disks of Examples 2-09 (a) to (c).

Comparative Example 2-01 A magneto-optical disk was prepared in the same manner as in Example 2-09 except that the second protective layer was not formed in Example 2-09.

The magneto-optical disks of Examples 2-01 to 2-09 and Comparative Example 2-01 were evaluated in the same manner as in Example 101. The results are shown in Table-202.

[0088]

[Table 3]

From Table-202 above, the effect of setting the aspect ratio of the conductive particles in the second protective layer to 5 or more is that, for example, in Examples 2-01 and 2-2 using Sb-coated TiO ₂ as the conductive particles. In -02 and 2-03, even when the content of Sb-coated TiO ₂ in the second protective layer was 10 parts by weight (about 9 wt%) relative to 100 parts by weight of resin, the surface resistivity was 1 × 10 ^10. Ω / □ or less is maintained, and no charge adsorption occurs in the head crash test, while Sb-coated TiO _{2 with} an average particle size of 1.5 μm and an aspect ratio of 1
In the case of Comparative Example 1-03 using, the surface resistivity is
It was 1.0 × 10 ¹¹ Ω / □, which is also apparent from the fact that electrostatic attraction occurred in the head crash test.

Example 3-01 First, an acrylate-based UV curable resin having the following composition was prepared.・ Urethane acrylate oligomer 18wt% ・ Dicyclopentadiene diacrylate 65wt% ・ Trimethylolpropane triacrylate 12wt
% ・ Photopolymerization initiator (trade name: Irgacure 184; manufactured by Ciba-Gaiki Co., Ltd.) 5 wt%

Next, 5 wt% of the charge transfer complex represented by the following structural formula (V) was dispersed in the ultraviolet curable resin composition so that the resin had a thermal conductivity of 0.1 to 0.3 W / mK. An ultraviolet curable resin composition for forming a protective layer was prepared.

Further, in the same manner as in Example 1-01, the magneto-optical recording layer and the Al-Cr film were sequentially laminated on the optical disk substrate.

Next, as shown in FIG. 6, the ultraviolet curable resin composition was applied onto the substrate by a spin coating method so as to cover the Al--Cr thin film and the magneto-optical recording layer, and the film thickness was 4 μm.
After forming the resin layer of UV lamp (233mW on the irradiation surface
/ Cm, wavelength 365 nm) for 7 seconds to cure the resin and form a resin protective layer to obtain a magneto-optical disk.

[0094]

[Outside 4]

Example 3-02 In Example 3-01, the charge transfer complex is represented by the following structural formula (V
A magneto-optical disk was produced in the same manner as in Example 3-01 except that the resin layer thickness was changed to 6 μm instead of I).

[0096]

[Outside 5]

Example 3-03 A polycarbonate disc substrate (diameter: 9 cm, thickness: 1.2 mm) having pregroups and prepits formed thereon was formed by a sputtering method using a SiN film having a thickness of 1000 Å and an amorphous film having a thickness of 200 Å. TbFeCoCr magnetic layer and SiN of 400 Å thickness
Magneto-optical recording layer composed of laminated films and a thickness of 60 thereon
A 0Å Al-Cr film was formed.

On the other hand, the resin protective layer was prepared by the following method. First, using pyrrole as a supporting electrolyte (n-B
u) ₄ NBF ₄ was dissolved in nitrobenzene containing 0.1 mol.

Next, a pair of platinum electrodes were immersed in this solution, and electrolytic polymerization was performed under conditions of a current density of 10 mA / cm ² and a voltage of 4 V to obtain a thermal conductivity of 0.6 to 0.7 W / m · K. A 4 μm polypyrrole film was prepared.

Next, the above-mentioned polypyrrole film was adhered onto the magneto-optical recording layer prepared above through an adhesive layer to prepare a magneto-optical disk.

However, as the adhesive, a two-component curing type acrylic adhesive (trade name: Olivine BPS4089-5; manufactured by Toyo Ink Mfg. Co., Ltd.) was used, and the thickness of the adhesive layer was 2 μm.
m. The thermal conductivity of the adhesive is 0.15 W / m.
It was K.

Example 3-04 A magneto-optical disk was prepared in the same manner as in Example 3-03, except that the resin protective layer was replaced by polypyrrole and a polytiphene film having a thickness of 6 μm was used. It was made.

(Example 3-05) In Example 3-03, a film having a polypyrrole content of 14 wt% (composed of a composite of polypyrrole having a thickness of 6 μm and a phenoxy resin-based polyanion instead of polypyrrole as the resin protective layer) Product name; SEC film; Nippon Ciba-Geigy Co., Ltd.)
A magneto-optical disk was produced in the same manner as in Example 3-03 except that the above was adopted.

(Example 3-06) A film having a polypyrrole content of 18 wt% which is a composite of polypyrrole having a thickness of 6 μm and a phenoxy resin-based polyanion instead of polypyrrole as the resin protective layer in Example 3-03. A magneto-optical disk was produced in the same manner as in Example 3-03 except that (trade name: SEC film; manufactured by Ciba-Geigy Co., Ltd.).

(Example 3-07) As a resin protective layer in Example 3-03, a film having a thickness of 6 μm in which 1 wt% of the charge transfer complex represented by the above structural formula (V) was dispersed in a polycarbonate resin was used. A magneto-optical disk was produced in the same manner as in Example 3-03 except that it was used.

(Example 3-08) In Example 3-03, a resin protective layer having a thickness of 4 μm was obtained by dispersing 1.5 wt% of the charge transfer complex represented by the structural formula (VI) in a polycarbonate resin. Example 3 except that a film was used
A magneto-optical disk was produced in the same manner as in 03.

The magneto-optical disks of Examples 3-01 to 3-08 described above were evaluated in the same manner as in Example 1-01.
The results are shown in Table-301.

[0108]

[Table 4]

Example 4-01 In Example 1-01, a silicone oligomer (trade name: AK-5; Toa Gosei) was added to the urethane acrylate-based UV-curable resin composition constituting the second protective layer. Chemical Co., Ltd.
A magneto-optical disk was produced in the same manner as in Example 1-01, except that 10% by weight of the resin composition was blended and the cured product was used as the second protective layer.

The magneto-optical disk thus obtained was mounted on a magneto-optical disk recording / reproducing apparatus equipped with the sliding magnetic head (71) shown in FIG. 7, and information was recorded and reproduced under the following conditions. Rotation speed: 800 rpm Magnetic field intensity: 150 Oe Frequency: 6 MHz Recording / reproducing beam wavelength: 830 nm Recording beam intensity: 5 mW Reproducing beam intensity: 1 mW As a result, C / N of 47 dB could be secured.

(Example 4-02) Sn was used as conductive particles.
Fluorinated acrylate resin sheet with a thickness of 4 μm containing 20 wt% O ₂ (trade name: KAYARAD INC
20631F, manufactured by Nippon Kayaku Co., Ltd.).
The pressure-sensitive adhesive used in 1 was applied to a thickness of 2 μm to prepare a protective pressure-sensitive adhesive sheet. This was pressure-bonded to an Al-Cr film formed on a substrate in the same manner as in Example 1-01 to produce a magneto-optical disk.

(Example 4-03) Sn as conductive particles
The pressure-sensitive adhesive used in Example 1-01 was applied onto a silicone acrylate resin (trade name: SPC-112S, manufactured by Nippon Kayaku Co., Ltd.) having a thickness of 6 μm containing 20 wt% of O ₂ and having a thickness of 2
μm was applied to prepare a protective pressure-sensitive adhesive sheet. This is an Al-Cr film formed on the substrate in the same manner as in Example 1-01.
A magneto-optical disk was produced by pressure-bonding and joining on the film.

(Example 4-04) In Example 1-01, a fluorine-based lubricant (trade name; Fomblin Z-25, manufactured by Montevideo Co., Ltd.) was used in the resin composition for forming the second protective layer. A magneto-optical disk was prepared in the same manner as in Example 1-01 except that 5% of) was added.

The magneto-optical disks of Examples 4-02 to 4-04 thus obtained were subjected to recording / reproduction using a sliding magnetic head in the same manner as in Example 4-01.
A value of 47 to 49 dB was obtained for the / N ratio.

(Example 5-01) Polyvinylidene chloride (trade name: KF-25, manufactured by Kureha Chemical Co., Ltd.) was coated on the first surface of a polyethylene terephthalate film having a thickness of 2 μm to a thickness of 2 μm, and further coated thereon. In Example 1
The UV curable resin containing SnO ₂ prepared in No. 01 was coated to a thickness of 2 μm and cured. Next, a pressure-sensitive adhesive was applied to the second surface of the film to a thickness of 2 μm to prepare a protective pressure-sensitive adhesive sheet. This was pressure-bonded to an Al-Cr film formed on the disk substrate in the same manner as in Example 1-01 to prepare a magneto-optical disk.

(Example 5-02) Vinyl chloride was formed on the first surface of a polyethylene terephthalate film having a thickness of 2 μm.
A vinylidene chloride copolymer (trade name; KF-35, manufactured by Kureha Chemical Co., Ltd.) is coated to a thickness of 2 μm, and the SnO ₂ -containing UV-curable resin prepared in Example 1-01 is further coated thereon. It was coated and cured to a thickness of 2 μm.

Then, Example 1 was applied to the second surface of the film.
The pressure-sensitive adhesive used in No. 01 was applied to a thickness of 2 μm to prepare a protective pressure-sensitive adhesive sheet. In the same manner as in Example 5-01, A
A magneto-optical disk was prepared by pressure bonding on the l-Cr film.

Example 5-03 A film having a thickness of 2 μm was prepared by using the ultraviolet curable resin prepared in Example 1-01. Then, the first surface of this film was coated with a vinyl chloride-vinylidene chloride copolymer to a thickness of 4 μm, and the SnO ₂ prepared in Example 1-01 was further formed thereon.
An ultraviolet curable resin containing the above was coated to a thickness of 2 μm and cured. Then, the adhesive used in Example 1-01 was applied on the second surface of the film to a thickness of 2 μm,
A protective adhesive sheet was created. This was pressure-bonded onto the Al—Cr film in the same manner as in Example 5-01 to prepare a magneto-optical disk.

Example 5-04 A protective pressure-sensitive adhesive sheet was prepared in the same manner as in Example 5-03 except that polyvinylidene chloride was used instead of the vinylidene chloride-vinylidene chloride copolymer. It was made.

(Example 5-05) The ultraviolet curing resin prepared in Example 1-01 was applied to the first surface of a polyvinylidene chloride film having a thickness of 2 μm to a thickness of 2 μm and cured.
On the second surface of the film, the UV curable resin containing SnO ₂ prepared in Example 1-01 was formed to a thickness of 2 μm.
m was applied and cured. Further, Example 1-01 was formed on the cured film of the ultraviolet curable resin formed on the first surface of the film.
The pressure-sensitive adhesive used in 2 was applied to a thickness of 2 μm to prepare a protective pressure-sensitive adhesive sheet. This was treated in the same manner as in Example 5-01 with Al-
A magneto-optical disk was prepared by pressure bonding on the Cr film.

(Example 5-06) A protective pressure-sensitive adhesive sheet was prepared in the same manner as in Example 5-04 except that a vinyl chloride-vinylidene chloride copolymer was used instead of polyvinylidene chloride, to prepare a magneto-optical disk. did.

With respect to the magneto-optical discs prepared in Examples 5-01 to 5-06, the byte error rate (B,
E, R) changes over time were measured. The results are shown in Table-501.
Shown in.

The measurements of B, E and R were carried out by a magneto-optical recording / reproducing inspection apparatus (trade name: LM31A, manufactured by Shibasoku Co., Ltd.). The measurement conditions are as follows: recording laser power 6 mW at innermost radius r = 24, recording laser power 8 mW at outermost radius r = 40, erase power 8 mW, reproduction power 1
mW and erasing / recording magnetic field was 300 Oe.

[0124]

[Table 5]

[0125]

As described above, according to the present invention, it is possible to obtain a magneto-optical recording medium capable of preventing the electrostatic attraction between the magnetic head and the protective layer and suppressing the deterioration of the recording / reproducing characteristics. .

Further, according to the present invention, by setting the aspect ratio of the conductive particles to be added to the resin protective layer to 5 or more, the protective layer is provided with the prescribed conductivity without lowering the strength of the resin protective layer. Can be granted.

Further, according to the present invention, by using an organic conductive compound for the protective layer, the electric resistance value of the surface can be lowered without increasing the thermal conductivity of the resin protective layer. A single layer can be formed, and the manufacturing process of a high-quality magneto-optical recording medium can be further simplified.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a method of recording information on an optical disc of the present invention.

FIG. 2 is a schematic sectional view of an embodiment of a magneto-optical disk of the present invention.

FIG. 3 is a schematic cross-sectional view of another embodiment of the magneto-optical disk of the present invention.

FIG. 4 is an explanatory view of a method for manufacturing a protective pressure-sensitive adhesive sheet according to the present invention.

FIG. 5 is an explanatory view of a method for manufacturing a magneto-optical recording medium according to the present invention.

FIG. 6 is a radial cross-sectional view of one embodiment of the magneto-optical disk of the present invention.

FIG. 7 is a schematic explanatory diagram of a recording method on a magneto-optical disk using a sliding magnetic head.

FIG. 8 is a correlation diagram showing an example of the relationship between the magnetic field strength in the magnetic layer and the distance between the magnetic layer and the magnetic head.

[Explanation of symbols]

11 board 12 Magneto-optical recording layer 13 Resin protective layer 14 Flying magnetic head 15 laser beam 21 Inorganic dielectric layer 22 Magnetic layer 23 Inorganic dielectric layer 24 First protective layer 25 Second protective layer 41 First Support Film 42 Second support film 43 Adhesive protection sheet 71 Sliding magnetic head

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 11/105

Claims (21)

(57) [Claims] 1. A magneto-optical recording layer and a resin protective layer are provided on a substrate, and a magnetic field is applied to the recording layer from the protective layer side by a magnetic field generating means and the recording layer is applied to the recording layer via the substrate. In a magneto-optical recording medium for irradiating a light beam to record information, the protective layer has a first surface facing the magnetic field generating means,
A second surface on the side facing the recording layer, the first surface of the protective layer has a surface resistivity of 1 × 10 ¹⁰ Ω / □ or less, and the second surface of the protective layer is heat-resistant. A magneto-optical recording medium having a conductivity of 10 W / m · K or less. 2. The magneto-optical recording medium according to claim 1, wherein the protective layer has a laminated structure of two layers, and only the protective layer on the recording layer side satisfies the thermal conductivity. 3. The magneto-optical recording medium according to claim 2, wherein the protective layer on the magnetic field generating means side contains conductive particles. 4. The magneto-optical recording medium according to claim 3, wherein the conductive particles are conductive ceramic particles. 5. The magneto-optical recording medium according to claim 4, wherein the conductive ceramic particles are acicular or scaly particles having an aspect ratio of 5 or more. 6. The magneto-optical recording medium according to claim 5, wherein the acicular conductive ceramic particles are antimony-modified potassium titanate particles. 7. The surface resistivity of the first surface of the protective layer is 1 ×
The magneto-optical recording medium according to claim 1, having a resistivity of 10 ³ to 1 × 10 ¹⁰ Ω / □. 8. The magneto-optical recording medium according to claim 3, wherein the conductive particles are made of an organic compound. 9. The magneto-optical recording medium according to claim 8, wherein the conductive particles made of the organic compound are particles made of a conductive polymer compound. 10. The magneto-optical recording medium according to claim 8, wherein the conductive particles made of the organic compound are particles made of a charge transfer complex. 11. The magneto-optical recording medium according to claim 10, wherein the charge transfer complex is a tetracene compound. 12. The magneto-optical recording medium according to claim 2, wherein the protective layer on the recording layer side is made of a curable polymer compound. 13. The magneto-optical recording medium according to claim 1, wherein the protective layer contains a conductive polymer compound. 14. The conductive polymer compound is a composite of a conjugated conductive polymer compound and a polyanion.
3. The magneto-optical recording medium of 3. 15. The magneto-optical recording medium according to claim 1, wherein the protective layer contains a charge transfer complex. 16. The magneto-optical recording medium according to claim 15, wherein the charge transfer complex is a derivative of tetracene. 17. The magneto-optical recording medium according to claim 1, wherein the resin protective layer has a thickness of 3 to 15 μm. 18. The magneto-optical recording medium according to claim 2, wherein the thickness of the protective layer on the recording layer side is at least 0.5 μm or more. 19. The protective layer contains acicular or scaly conductive particles having an aspect ratio of 5 or more.
Magneto-optical recording medium. 20. A magneto-optical recording layer and a resin protective layer are provided on a substrate, and a magnetic field is applied to the recording layer from the protective layer side by a magnetic field generating means, and the recording layer is provided through the substrate. In a method of manufacturing a magneto-optical recording medium for irradiating a light beam on a surface to record information, the surface resistivity of at least one surface is 1 × 10 ¹⁰ Ω /
□ The resin sheet below is adhered onto the magneto-optical recording layer through an adhesive layer having a thermal conductivity of 10 W / m · K or less so that the surface faces the magnetic field generating means, A method of manufacturing a magneto-optical recording medium, which comprises the step of forming a protective layer on the magneto-optical recording layer by the method. 21. The method of manufacturing a magneto-optical recording medium according to claim 20, wherein the adhesive layer has a thickness of 0.5 μm or more.