JPH03137836A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To prevent or to limit permeation of corrosive elements from a resin substrate by providing an intermediate layer containing no corrosive element and comprising such material that prevents permeation of corrosive elements between the resin substrate and a thin film layer. CONSTITUTION:The intermediate layer 2 is provided on side 1a where signal patterns are formed of the resin substrate 1, on which a thin film layer 3 containing at least a magneto-optical recording film is deposited. The substrate 1 consists of transparent resin material such as polycarbonate, polymethyl methacrylate, polymethylpentene, epoxy, etc. The intermediate layer 2 contains no corrosive element such as Cl, S, and F, and consists of such material that prevents permeation of these corrosive elements. Further, such a material, for example, tetrabutyl tin, that can easily make bonds with corrosive elements is added to the material of the intermediate layer 2 to trap the corrosive elements in the layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium, and particularly to a means for preventing corrosion of a magneto-optical recording film formed on a substrate.

[Conventional technology]

Conventionally, magneto-optical recording media have been proposed in which a thin film layer containing at least a magneto-optical recording film is formed on a signal pattern forming surface of a resin substrate.

The magneto-optical recording film is made of a magnetic material such as a rare earth-transition metal-based amorphous alloy, and is easily corroded. In addition, the film thickness of the magneto-optical recording film is 30 to 50 (n
m).

Easily damaged by the slightest impact. In order to prevent the problem of peeling, a protective film is usually applied to the surface of the magneto-optical recording film.

By the way, it has been recognized that the corrosion of the magneto-optical recording film is caused by water penetrating through the resin substrate and the protective film, so it has been recognized that the corrosion of the magneto-optical recording film is caused by water penetrating through the resin substrate and the protective film. Anti-corrosion treatments have been proposed.

A magneto-optical recording medium that has been subjected to waterproofing has a longer lifespan effect than a magneto-optical recording medium that has not been subjected to any waterproofing.

[Problem to be solved by the invention]

However, magneto-optical recording media are practically required to have a longer lifespan, and conventional corrosion protection measures are still insufficient.

As a result of research, the applicant of the present application has learned the following facts regarding the corrosion of magneto-optical a film.

■Magneto-optical recording films are easily corroded in high-temperature, high-humidity environments (but hardly corrode in high-temperature, low-humidity environments.

However, when a glass substrate is used, the magneto-optical recording film is less likely to corrode even in a high temperature and high humidity atmosphere.

■As a result of analysis, it was confirmed that the corroded magneto-optical recording film had become a hydroxide.

■Chlorine, sulfur, fluorine, etc. are released from the corroded magneto-optical recording film! 1 Corrosive elements detected.

■Corrosion of the magneto-optical recording film occurs from the interface with the substrate.

■Corrosive elements such as chlorine, sulfur, and fluorine are detected in resin substrates.

From these facts, the corrosion mechanism of magneto-optical recording film is
It is estimated that the following is true.

First, corrosive elements contained in the resin substrate cause a chemical reaction with metal elements in the magneto-optical recording film. The corrosive element is chlorine (
Taking as an example the case where the metal element of the magneto-optical recording medium that causes a chemical reaction with C1) is terbium (Tb; a divalent metal), this chemical reaction is explained using a chemical formula as follows.

T b + 3 CI-→TbCl3- +2 e・
・ ・ ・ ・(1) Next, the TbC14 generated by this reaction and the moisture that has entered from the outside through the protective film cause the following chemical reaction.

TbC1: i-+2820 1 + T b (OH) z +28 + 3 CI-
”・(2) Furthermore, C1− produced by this reaction
The chemical reaction of formula (1) occurs again, and corrosion progresses continuously.

Therefore, corrosion of the magneto-optical recording film can be prevented by preventing the intrusion of at least one of corrosive elements and moisture. However, resin substrates have some degree of water permeability, and it is difficult to completely prevent water permeability, and if treatments are applied to prevent this, the cost of the magneto-optical recording medium will increase significantly.

On the other hand, it is possible to prevent corrosive elements from entering the magneto-optical recording film relatively easily by forming an intermediate layer between the substrate and the thin film layer containing the magneto-optical recording film.

The present invention has been made based on this knowledge, and is capable of preventing corrosion of a magneto-optical recording film by preventing corrosive elements from entering the magneto-optical recording film, thereby providing a long-life magneto-optical recording medium. The purpose is to provide the following.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a magneto-optical recording medium in which a thin film layer including at least one magneto-optical recording film is formed on the signal surface of a resin substrate. An intermediate layer made of a substance that does not contain corrosive elements that corrode the magneto-optical recording film and prevents the permeation of corrosive elements was provided between the magneto-optical recording film and the thin film layer.

As the substance that does not contain any corrosive elements and prevents the corrosive elements from permeating, a substance to which the corrosive elements cannot penetrate at all may be used, or a substance that captures the corrosive elements that have invaded and transfers them to the thin film layer. It is also possible to use a substance that prevents the movement of.

[Effect]

By providing the above-mentioned intermediate layer between the resin substrate and the magneto-optical recording film, the corrosive elements in the resin substrate, which are the main cause of corrosion of the magneto-optical recording film, do not enter the magneto-optical recording film, and the optical Corrosion of the magnetic recording film is prevented. Therefore, it is possible to provide an optical information recording medium with excellent corrosion resistance and long life.

〔Example〕

FIG. 1 is a cross-sectional view of main parts showing the overall structure of a magneto-optical recording medium according to the present invention, in which an intermediate layer 2 is formed on a signal pattern forming surface 1a of a resin substrate 1, and on this intermediate layer 2 at least A thin film layer 3 including a magneto-optical recording film is laminated.

The resin substrate 1 is made of a transparent resin material such as polycarbonate (PC), polymethyl methacrylate (PMMA), polymethylpentene, or epoxy. One side of the resin substrate 1 has an uneven signal pattern such as a pre-group for guiding a recording/reproducing radiation beam (for example, a laser beam) and a pre-pit for displaying a pre-format signal (see Figs. 2 to 5). formed in the shape.

The signal pattern is formed by an appropriate method depending on the type of substrate material. For example, injection molding is suitable for thermoplastic resins such as PC and PMMA, and 12P method (photocurable resin method) and casting method are suitable for thermosetting resins such as epoxy. Furthermore, a casting method is suitable for ultraviolet curable resins.

The intermediate layer 2 is formed from a material that does not contain corrosive elements such as chlorine, sulfur, and fluorine and prevents the permeation of these corrosive elements. Specifically, silicon nitride (
SiiNx, however, 3≦X≦4), silicon oxide (Si
Examples include Ox (1≦X≦2), styrene plasma polymer, polyethylene, polyvinyl alcohol, cellulose nitrate, acrylate-based ultraviolet curing resin, and the like. Furthermore, it is also possible to add a substance that easily binds to a corrosive element, such as Te1-butyltin, to these substances, so that the intermediate layer 2 captures the corrosive element.

In order to protect the inner circumferential end 3a and outer circumferential end 3b of the thin film layer 3, the intermediate layer 2 is preferably formed over a wider area than the thin film WI3, as shown in FIG.

As a means for forming the intermediate layer 2, thin film forming means such as a sputtering method, a vacuum evaporation method, a plasma polymerization method, a spin coating method, etc. can be applied depending on the type of intermediate layer material.

The thin film layer 3 is composed of at least one magneto-optical recording film, and if necessary, a laminate of one or more thin films made of other materials and the magneto-optical recording film can also be used.

The film structure of the thin film layer 3 is illustrated in FIGS. 2 to 5.

In the magneto-optical recording medium of FIG. 2, the thin film layer 3 is arranged from the intermediate layer 2 side to the magneto-optic recording film 4 and the resin substrate
A dielectric film 5 formed of a dielectric having a higher refractive index than
It has a 3M structure consisting of a metal protective film 6. In this figure, 7 indicates a pre-group, and 8 indicates a pre-pit.

The magneto-optical recording film 4 is made of 1, for example, TbFeCo, TbFe, T
eCo, TbFe-GdTbFe, TbDyFe, Tb
DyFaCo, GdTbFa.

G d T b F e Co , Q d T b
F e G e , G d Co .

GdTbCo, TbFe/GdFe, TbFe/GdF
eCo, TbNiFe, DyFeGdCo.

It can be formed using any known magneto-optical recording material such as MnCuBi or (noble metal) -TbFe.

The dielectric film 5 causes multiple reflections of the reproduction light between the magneto-optical recording film 4 and the metal protective film 6, and apparently increases the above Kerr rotation angle to produce a reproduction signal with a high CN ratio. It is formed of a dielectric material whose refractive index is larger than that of the resin substrate 1. As a dielectric material,
Any material such as silicon oxide, silicon nitride, or aluminum nitride can be used, but non-oxide materials are particularly preferred in order to prevent corrosion of the magneto-optical recording film 4.

The metal protective film 6 is formed of a highly reflective metal material such as aluminum.

In the magneto-optical recording medium of FIG. 3, the thin film layer 3 is arranged from the intermediate layer 2 side to the magneto-optical recording film 4 and the resin substrate 1
A dielectric film 5 formed of a dielectric having a higher refractive index than
It has a four-layer structure consisting of a metal reflective film 9 and a resin protective film 10.

The metal reflective film 9 is formed of a metal material with high reflectance, such as aluminum.

Further, the resin protective film 10 can be formed using any resin material with low water permeability, but ultraviolet curable resin is particularly preferred because of its high productivity.

Other parts with the same reference numerals are formed in the same manner as in FIG. 2.

In the magneto-optical recording medium of FIG. 4, the thin film layer 3 includes, from the intermediate layer 2 side, a first dielectric film 11 formed of a dielectric material having a higher refractive index than the resin substrate l; a magnetic recording film 4; and a second dielectric film 12 made of the same material as the first dielectric film 11.

It has a four-layer structure consisting of a metal protective film 6.

The first dielectric film 11 and the second dielectric film 12 are
It is formed using the same material as the dielectric film 5 shown in the figure.

Other parts with the same reference numerals are formed in the same manner as in FIG. 2.

In the magneto-optical recording medium of FIG. 5, the thin film layer 3 includes, from the intermediate layer 2 side, a first dielectric film 11 formed of a dielectric material having a higher refractive index than the resin substrate 1; It has a five-layer structure consisting of a magnetic recording film 4, a second dielectric film 12 made of the same material as the first dielectric film 11, a metal reflective film 9, and a resin protective film 10. ing.

The material of each part constituting the magneto-optical recording medium of this example is the same as that explained in any of Figures 2 to 4, so to avoid duplication, the same reference numerals are used for the corresponding parts. will be displayed and the explanation will be omitted.

The thin film layer 3 is formed, for example, by a vacuum film forming method such as a vacuum evaporation method or a sputtering method.

Hereinafter, experimental examples of the present invention will be shown, and the effects of the present invention will be discussed.

<First Experimental Example> An intermediate layer made of 5i3Nx (3≦X≦4) was formed on the signal pattern surface of a polycarbonate substrate by RF sputtering. The film forming conditions are as shown in Table 1.

Next, a TbFeCo-based magneto-optical recording film was laminated on the intermediate layer. The film-forming conditions for this magneto-optical recording film are as shown in Table 2.

Second Example> An intermediate layer made of 5iOy (where 1≦y≦1) was formed on the signal pattern surface of a polycarbonate substrate by RF sputtering. The film forming conditions are as shown in Table 4.

Next, a silicon nitride film was laminated as a dielectric film on this magneto-optical recording film. The conditions for forming this dielectric film are as shown in Table 3.

Thereafter, in the same manner as in the first embodiment, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on the intermediate layer.

Finally, an aluminum alloy film was laminated as a metal protective film on this dielectric film to produce the magneto-optical recording medium shown in FIGS. 1 and 2.

Third Experimental Example> An intermediate layer made of 5iOx (1≦X≦2) was formed on the signal pattern surface of a polycarbonate substrate by electron beam evaporation. The film forming conditions are as shown in Table 5.

It is.

From Table 5 onwards, in the same manner as in the first embodiment, a magneto-optical recording film, a dielectric film and a metal protective film are laminated on the intermediate layer to produce the magneto-optical recording shown in FIGS. 1 and 2. A medium was prepared.

Fourth Experimental Example> An intermediate layer of a styrene plasma polymerized film was formed on the signal pattern surface of a polycarbonate substrate by plasma polymerization. The film forming conditions are as shown in Table 6. In the same manner as in the first embodiment, a magneto-optical recording film, a dielectric film and a metal protective film were laminated on the intermediate layer. The magneto-optical recording medium shown in the figure was manufactured.

<Fifth Experimental Example> A polyethylene intermediate layer was formed on the signal pattern surface of a polycarbonate substrate by resistance heating vapor deposition. The film forming conditions are as shown in Table 7.

Thereafter, in the same manner as in the first embodiment, a magneto-optical recording film, a dielectric film, and a metal protective film were laminated on the intermediate layer to produce the magneto-optical recording medium shown in FIGS. 1 and 2. did.

<Sixth Experimental Example> An intermediate layer made of polyvinyl alcohol was formed on the signal pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, polyvinyl alcohol powder with a degree of polymerization of 2000 and a degree of saponification of 88.0% was prepared, and decantation with water was repeated several times to remove sodium acetate contained in the polyvinyl alcohol.

Next, water was added to this polyvinyl alcohol, and 60~
The mixture was heated to 80° C. and stirred for about 2 hours to completely dissolve 2.5% by weight of polyvinyl alcohol in water.

Next, about 10% by weight of ammonium dichromate based on polyvinyl alcohol was added to this aqueous solution and completely dissolved.

Further, this aqueous solution was filtered through a 0.2 μm filter to remove foreign matter, and an aqueous solution of polyvinyl alcohol and ammonium dichromate for forming the base layer was prepared.

Next, the aqueous solution of polyvinyl alcohol and ammonium dichromate was spin coated on the signal pattern surface of the substrate.

Next, this film was irradiated with ultraviolet rays for several minutes using an ultra-high pressure mercury lamp to crosslink polyvinyl alcohol and ammonium dichromate to form a complex of the two. As a result, an intermediate layer made of the complex was formed to a thickness of about 80 nm on the signal pattern surface of the polycarbonate substrate.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

Seventh Experimental Example> An intermediate layer made of polyvinyl alcohol containing lead acetate was formed on the signal pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, the same aqueous solution of polyvinyl alcohol and ammonium dichromate was prepared by the method explained in the sixth experimental example.

Next, add about 5% of the polyvinyl alcohol to the aqueous solution of polyvinyl alcohol and ammonium dichromate.
% by weight of lead acetate powder was added and completely dissolved.

Next, this aqueous solution of polyvinyl alcohol, ammonium dichromate, and lead acetate was spin-coded onto the signal pattern surface of the substrate, and then ultraviolet rays were irradiated to coat it to a film thickness of about 80 mm.
An intermediate layer of 100 nm was formed.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

<Eighth Experimental Example> An intermediate layer made of cellulose nitrate was formed on the signal pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, cellulose nitrate having a molecular weight of 220,000 and containing about 30% by weight of isopropyl alcohol and methanol were prepared in a weight ratio of 15:985.

Next, cellulose nitrate was added to methanol and stirred for 10 hours to completely dissolve.

Next, this solution was filtered, and then spin-coated onto the signal pattern surface of a polycarbonate substrate.

Next, this thin film was air-dried to form an intermediate layer made of cellulose nitrate with a thickness of about 80 nm.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

Ninth Experimental Example> An intermediate layer made of cellulose nitrate containing tetrabutyltin was formed on the M pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, a methanol solution of cellulose nitrate identical to that described in the eighth experimental example was prepared.

Next, about 5% by weight of tetrabutyltin based on the cellulose nitrate was added to the methanol solution of cellulose nitrate and completely dissolved.

Next, this solution was filtered through a filter, and then spin-coated onto the signal pattern surface of a positive substrate.

Next, this thin film was air-dried to form an intermediate layer made of cellulose nitrate containing tetrabutyltin and having a thickness of about 80 nm.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

10th Experimental Example> An intermediate layer made of an acrylate ultraviolet curable resin was formed on the signal pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, an acrylate-based ultraviolet curing resin (for example, "ThreeBond 30X400J" manufactured by ThreeBond) was completely dissolved in isopropyl alcohol.

Next, this solution was filtered through a filter, spin-coated onto the signal pattern surface of a polycarbonate substrate, and baked at 80° C. for several minutes to remove the solvent remaining in the film.

Next, this thin film was irradiated with ultraviolet rays from a metal halide lamp to form an intermediate layer made of an acrylate ultraviolet curing resin with a thickness of about 1100 nm.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

<Eleventh Experimental Example> An intermediate layer made of an acrylate ultraviolet curing resin containing tetrabutyltin was formed on the signal pattern surface of a polycarbonate substrate by spin coating. A specific method for forming the intermediate layer is as follows.

First, the same acrylate-based ultraviolet curing resin solution was prepared by the method explained in the 10th experimental example.

Next, approximately 1% by weight of tetrabutyltin based on the acrylate-based ultraviolet curable resin was added to this solution and completely dissolved.

Next, in the same manner as in the 10th experimental example, spin coating,
Baking and ultraviolet irradiation were performed to form an intermediate layer made of an acrylate ultraviolet curable resin containing tetrabutyltin and having a thickness of approximately 1100 nm.

Finally, a magneto-optical recording film, a dielectric film, and a metal protective film were sequentially laminated on this intermediate layer under the same conditions as in the first embodiment, as shown in FIGS. 1 and 2. A magneto-optical recording medium was fabricated.

The magneto-optical recording medium of each of the above experimental examples according to the present invention and the magneto-optical recording medium without any anti-corrosion treatment were heated at 60°C x 9
An accelerated environmental test was conducted by leaving the sample in a 0% RH atmosphere. Figure 6 shows the results of this accelerated environmental test. The horizontal axis of this graph is the test time, and the vertical axis is the reflectance of the thin film layer.The solid line is the data for the magneto-optical recording medium according to the present invention, and the data for the magneto-optical recording medium according to the conventional example. The data is shown with a two-dot chain line. However, the wavelength of the measurement light is 780 nm.
The lines showing the measurement results are the average values of three samples of the same type.

As is clear from this graph, the reflectance of magneto-optical recording media whose resin substrates have not been subjected to any anti-corrosion treatment begins to decrease significantly after about 24 hours, whereas No decrease in reflectance was observed in any of the coated optical information recording media of this example even after 2000 hours. From the above test results, it was found that the magneto-optical recording medium of the present invention has a remarkable effect on improving the corrosion resistance of the thin film layer.

In each of the above experimental examples, a polycarbonate substrate was used as an example of the resin substrate, but similar effects can be obtained with other resin substrates such as epoxy resin, polymethyl methacrylate, polymethyl pentene, and polyolefin.

Furthermore, in each of the above experimental examples, explanations have been given by taking as an example a magneto-optical recording medium in which the thin film layer is formed in a three-layer structure consisting of a magneto-optical recording film, a dielectric film, and a metal protective film.
Similar effects can be obtained with magneto-optical recording media having other thin film structures as shown in the figure.

Further, in each of the above embodiments, only the influence of chlorine as a corrosive element has been described, but a similar effect is also exerted on corrosion of a metal layer caused by, for example, sulfur or fluorine.

The gist of the present invention is that an intermediate layer is formed between the resin substrate and the magneto-optical recording film using a material that is difficult for corrosive elements to pass through, but in addition to this, other anti-corrosion treatments may be combined. can be done arbitrarily. Other anticorrosion treatments include: (1) irradiating the substrate with energy such as oxygen plasma, sputter etching, glow discharge, electron beam, and ultraviolet rays; There are two methods: 1. Baking the substrate; 2. Selecting a material with a low content of corrosive elements as the substrate material.

Furthermore, a water-impermeable layer made of glass or the like and having a higher hardness than the resin substrate can be formed on the light beam incident surface of the resin substrate together with the intermediate layer.

In addition, measures such as laminating two magneto-optical recording media shown in the above embodiment to form a double-sided recording type magneto-optical recording medium, or attaching a hub for magnetic clamping to the magneto-optical recording medium may be provided as necessary. It can be adopted as appropriate.

〔Effect of the invention〕

As explained above, according to the present invention, seepage of corrosive elements from a resin substrate can be prevented or significantly restricted. Therefore, even if left in a high-temperature, high-humidity atmosphere, there is no chemical reaction between the magneto-optical recording film and corrosive elements.
Alternatively, the progress speed of these chemical reactions is slowed down, and the life of the magneto-optical recording medium can be significantly extended.

[Brief explanation of the drawing]

The figures are all for explaining the present invention, and FIG. 1 is a cross-sectional view showing an example of a magneto-optical recording medium, and FIGS. 2 to 5 are main part cross-sectional views showing various laminated structures of thin film layers. , FIG. 6 is a graph illustrating the invention in detail. 1...Resin substrate, 2...Intermediate layer, 3
...Thin film layer, 4... Magneto-optical recording film, 5
...Dielectric film, 6...Metal protective film,
7... Pre-group, 8... Pre-pit, 9... Metal reflective film, 10... Resin protective film, 11... First dielectric film, 12...
...Second dielectric film. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Exam time (H'')

Claims (9)

[Claims] (1) In a magneto-optical recording medium in which a thin film layer containing at least one magneto-optical recording film is formed on the signal surface of a resin substrate mixed with a corrosive element that corrodes the magneto-optical recording film,
A magneto-optical recording medium characterized in that an intermediate layer is provided between the resin substrate and the thin film layer and is made of a substance that does not contain the corrosive element and prevents the corrosive element from passing through. (2) The magneto-optical recording medium according to claim 1, wherein the intermediate layer does not contain at least one corrosive element selected from chlorine, sulfur, and fluorine, and is selected from chlorine, sulfur, and fluorine. 1. A magneto-optical recording medium characterized in that it is formed of a substance that prevents the transmission of at least one corrosive element. (3) In the magneto-optical recording medium according to claim 1, the intermediate layer is made of silicon nitride (Si_3Nx, where 3<x<
4), silicon oxide (SiOx, 1<x<2),
1. A magneto-optical recording medium characterized in that it is formed using at least one substance selected from styrene plasma polymer, polyethylene, polyvinyl alcohol, cellulose nitrate, and acrylate ultraviolet curing resin. (4) In the magneto-optical recording medium according to claim 1, in the intermediate layer, there is at least one element that easily combines with the corrosive element.
A magneto-optical recording medium characterized by adding various kinds of substances. (5) The magneto-optical recording medium according to claim 4, wherein at least one of tetrabutyltin and lead acetate is added to the intermediate layer as a substance that easily combines with the corrosive element. magneto-optical recording medium. (6) In the magneto-optical recording medium according to claim 1, the thin film layer includes, from the intermediate layer side, a magneto-optical recording film and a dielectric material having a higher refractive index than the resin substrate. A magneto-optical recording medium characterized by having a three-layer structure consisting of a film and a metal protective film. (7) In the magneto-optical recording medium according to claim 1, the thin film layer includes, from the intermediate layer side, a magneto-optical recording film and a dielectric material having a higher refractive index than the resin substrate. A magneto-optical recording medium characterized by having a four-layer structure consisting of a film, a metal reflective film, and a resin protective film. (8) In the magneto-optical recording medium according to claim 1, the thin film layer includes, from the intermediate layer side, a first dielectric film formed of a dielectric material having a higher refractive index than the resin substrate; A magneto-optical recording medium having a four-layer structure consisting of a magnetic recording film, a second dielectric film made of the same material as the first dielectric film, and a metal protective film. . (9) In the magneto-optical recording medium according to claim 1, the thin film layer includes, from the intermediate layer side, a first dielectric film formed of a dielectric material having a higher refractive index than the resin substrate; It has a five-layer structure consisting of a magnetic recording film, a second dielectric film made of the same material as the first dielectric film, a metal reflective film, and a resin protective film. magneto-optical recording medium.