JPH097172A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE: To obtain a magnetic recording medium having excellent durability and satd. magnetic flux density (Bs) by forming recessed parts on the front surface of a base film and depositing a magnetic metal by evaporation thereon and a production method therefor. CONSTITUTION: The base film 1 is used as the base of the magnetic recording medium of a vapor deposition type and the recessed parts 2 are formed by ion beam etching on its front surface. Columns 3, 3' of a magnetic layer where the columns 3' varying in length are formed at places on the surface of the base film having such recessed parts 2 formed. Thereby, the bondability of the base film 1 and the columns 3, 3' is improved and the packing property of the metal crystal is improved and, therefore, the durability and Bs are improved. Further, the recessed parts are formed on the front surface of the magnetic layer as well and, therefore, the magnetic recording medium having a small coefft. of friction and good traveling stability is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor-deposited magnetic recording medium and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a magnetic recording medium, an evaporation type in which a magnetic layer made of a metal thin film containing no binder is attached on a non-magnetic base film by a vacuum evaporation method in which a magnetic metal is evaporated on a base film in a vacuum. Magnetic recording media are known. In recent years, magnetic recording is in the direction of high-density recording, and a vapor-deposited magnetic recording medium is promising for high-density recording because the magnetic layer does not contain a binder and therefore the density of the magnetic material can be increased. Has been done.

Generally, in the manufacture of a magnetic recording medium by a vacuum vapor deposition method, a magnetic film such as Fe, Co and Ni, a Co-Ni system or C is formed on a base film continuously running in a vacuum atmosphere.
An o-Cr magnetic alloy is deposited by vapor deposition to form a magnetic layer. As a base film, polyethylene terephthalate (PE) having a thickness of about 3 to 50 μm is used.
Polyesters such as T) and the like, polyolefins such as polyethylene and polypropylene, and plastics such as polycarbonate and polyamide are used.

[0004]

Conventionally, the base film was bombarded to activate the surface of the film before the vapor deposition step, and the magnetic metal was vapor-deposited thereon. According to this method, a magnetic layer column 22 having the same shape as shown in FIG. 2A is formed on a substantially uniform film 21 surface as shown in FIG. 2B.
Is formed.

However, in the ordinary vapor deposition method, since the film is formed at the interface between the film and the magnetic layer in the region where the amount of metal vapor is small (the initial stage of vapor deposition), the amount of metal adhesion is small, and the binding force and crystallinity of the film and column are low. It is inferior to the upper part of the column. Therefore, the durability and running stability tended to be insufficient. Further, the saturation magnetic flux density (Bs) was insufficient because the packing property of the columns was not sufficient.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, formed a recess on the surface of the base film by ion beam etching or the like.
By evaporating a magnetic metal thereon, the binding property between the magnetic layer and the film is improved and the durability is excellent, and the packing property between columns is improved, so that a magnetic recording medium excellent in Bs can be obtained. The present invention has been completed and the present invention has been completed.

That is, the present invention relates to a method of manufacturing a magnetic recording medium including a step of depositing a magnetic metal in a vacuum to form a magnetic layer on a base film. A method of manufacturing a magnetic recording medium, comprising depositing a magnetic metal on the surface.

Further, according to the present invention, in a method for manufacturing a magnetic recording medium including a step of depositing a magnetic metal in vacuum to form a magnetic layer on a base film, concave portions are uniformly formed on the surface of the base film. Then, the present invention provides a method for manufacturing a magnetic recording medium, which comprises depositing a magnetic metal on the surface of the base film in vacuum to form a magnetic layer. In this method, the formation of the concave portion of the base film and the vapor deposition can be continuously performed.

The present invention also provides a magnetic recording having a base film having a concave portion formed on its surface by ion beam etching, and a magnetic layer formed by depositing a magnetic metal on the surface of the base film having the concave portion. A method for manufacturing a medium is provided.

As shown in FIG. 1B, the magnetic recording medium of the present invention is one in which a magnetic metal is vapor-deposited on the surface of the base film 1 in which the recesses 2 are formed by ion beam etching. As shown in a), it has a structure in which columns 3'having different lengths are mixed in places. As a result, the binding property between the film 1 and the columns 3, 3'is improved, and the packing property of the metal crystals is improved.
The durability and Bs are improved. Further, since the concave portion is formed on the surface of the magnetic layer, the magnetic recording medium has a small friction coefficient.

In the present invention, the recess on the surface of the base film may be formed by any method, but it is preferably formed by ion beam etching. Ion beam etching is a process for producing a uniform ion beam by an extraction electric field of about 1 kilovolt (kV) from a low-pressure discharge ion source, and physical processing of an object mainly using kinetic energy of ions. , Directional processing is possible. Also in the present invention, the ion beam etching method may be carried out according to a conventionally known method, and specifically, a method of irradiating an ion beam from an ion gun toward the surface of the base film moving in a vacuum can be mentioned. . Kaufman type ion gun is generally used as the ion gun, and argon gas is supplied as the gas.
Examples thereof include nitrogen gas and oxygen gas. The accelerating voltage of the ion gun is about 1 kV, although it depends on the type of gas and the degree of recesses formed in the base film. It is also possible to use a known ECR type or other known device as the ion etching means.

The recesses formed on the surface of the base film may be formed uniformly, but are preferably formed at intervals of 20 to 600 nm (L in FIG. 1 (b)). It is more preferable that the recesses are formed at such intervals in terms of the binding property between the magnetic layer and the film and the column formation of the magnetic layer.
The depth of the recess is 30 to 300 nm, and the shape is not limited, but the diameter
A circular shape of 20 to 300 nm is common. The degree of formation of the recess is not limited to this range, and may be appropriately determined depending on the material of the base film, the type of magnetic metal, and the like.

In carrying out the method of manufacturing a magnetic recording medium of the present invention, after the base film 31 is previously ion-beam etched by the ion gun 32 in the vacuum chamber 30 by the apparatus as shown in FIG. Alternatively, the magnetic layer may be separately formed by an ordinary vacuum vapor deposition apparatus, or ion beam etching and vapor deposition may be continuously performed by an apparatus as shown in FIG. In FIG. 4, the chamber
Ions such as argon ions are radiated from the ion gun 44 toward the base film 43 running on the can roll 42 in the 40 to form a recess on the surface of the base film 43, and then the base film 43 moves to the chamber 41 and moves to the can roll. Magnetic metal is vapor-deposited on 45. The base film is passed through a bombarding device 46 as it moves from chamber 40 to chamber 41. As a result, the magnetic recording medium of the present invention having the structure as shown in FIG.

In the present invention, examples of the magnetic material forming the magnetic layer include ferromagnetic metal materials used in the production of ordinary metal thin film type magnetic recording media, such as Co, Ni,
Ferromagnetic metals such as Fe, Fe-Co, Fe-Ni, Co-Ni, Fe
-Co-Ni, Fe-Fh, Fe-Cu, Co-Cu, Co-Au, Co-Y,
Co-La, Co-Pr, Co-Gd, Co-Sm, Co-Pt, Ni-Cu, Mn
-Bi, Mn-Sb, Mn-Al, Fe-Cr, Co-Cr, Ni-Cr, Fe-
Ferromagnetic alloys such as Co-Cr and Ni-Co-Cr are exemplified. The magnetic layer is preferably a thin film of iron or a thin film of a ferromagnetic alloy mainly composed of iron, and particularly preferably a ferromagnetic alloy mainly composed of iron, cobalt and nickel, and at least one selected from nitrides and carbides thereof. . The thickness of the magnetic layer is not limited, but is about 500 to 3000Å.

For high density recording, the magnetic layer of the magnetic recording medium is preferably formed on the substrate by oblique vapor deposition. The method of oblique vapor deposition is not particularly limited and is based on a conventionally known method. The degree of vacuum during vapor deposition is about 10 ⁻⁴ to 10 ⁻⁷ Torr. The magnetic layer formed by vapor deposition may have either a single-layer structure or a multi-layer structure, and in particular, the durability can be improved by introducing an oxidizing gas to form an oxide on the surface of the magnetic layer.

In the present invention, a protective layer may be provided on the magnetic layer. The protective layer is formed by depositing carbon or carbide, nitride, oxide, particularly diamond-like carbon, diamond, boron carbide, silicon carbide, boron nitride, silicon nitride, silicon oxide, aluminum oxide, etc. on the magnetic layer. It is preferable to form the protective layer made of diamond-like carbon, and it is most preferable to form the protective layer. These protective layers are preferably formed in vacuum by an ECR method using microwaves or a method using high frequency (RF). The thickness of the protective layer is not particularly limited, but is appropriately 10 to 300 Å, preferably 30 to 150 Å.

Further, in the present invention, a lubricant layer may be formed on the magnetic layer or the protective layer. The lubricant layer may be formed by dissolving a suitable lubricant in a solvent and coating it in the air by a conventional method, or by spraying the lubricant in a vacuum. A back coat layer may be formed on the surface of the base film opposite to the surface on which the magnetic layer is formed. The back coat layer may be formed by applying a liquid in which carbon black or the like is dispersed in a suitable solvent, or by vapor-depositing a metal or a metalloid by a physical vapor deposition method (PVD), particularly a thermal evaporation method or a sputtering method. You may let me. The thicknesses of these lubricant layer and back coat layer are not limited.

The base film constituting the magnetic recording medium of the present invention includes polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate and cellulose diacetate; polycarbonates; polychlorination. Vinyl; polyimide; plastics such as aromatic polyamide are used. In particular, polyethylene terephthalate is preferable from the operation of forming a recess by ion beam etching. The thickness of these base films is about 3 to 50 μm.

[0019]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A magnetic recording medium was manufactured by continuously performing ion beam etching and vapor deposition using the apparatus shown in FIG. That is,
A PET film 43 with a thickness of 10 μm and a width of 15 cm on the unwinding roll 48.
Is set, the can roll 42 in the chamber 40 is run at a running speed of 10 m / min, and the surface of the film 43 is irradiated with an ion beam from an ion gun 44. At this time, the gas supplied to the ion gun 44 is argon gas, and the base film 43 is generated by generating argon ions at a pressurizing voltage of 1 kV.
To the surface of the base film 43 with a diameter of 50 nm,
Holes having a depth of 100 nm were formed at 100 nm intervals. The chamber 40 has a vacuum degree of 5 × 10 ⁻³ by a vacuum means (not shown).
I kept it at Torr.

Next, the base film 43 having holes formed on the surface by ion beam etching is used in a bombarding apparatus.
After passing through 46, it was moved to the chamber 41, cobalt contained in the crucible 47 was vapor-deposited, and a magnetic layer having a thickness of 1600Å was formed on the surface of the base film 43 where the concave portion was formed. The chamber 41 has a degree of vacuum of 2 by a vacuum means (not shown).
It was kept at × 10 ^-5 Torr.

After the base film having the magnetic layer formed thereon is wound up by a winding roll 49, a backcoat layer made of carbon black having a thickness of 5000Å and a binder resin made of a vinyl chloride resin and a urethane prepolymer by a conventional method. Was formed on the surface of the base film opposite to the magnetic layer, and a lubricant layer made of perfluoropolyether having a thickness of 20Å was formed on the magnetic layer by a conventional method.

The obtained film was cut to a width of 8 mm and loaded into a cassette case to obtain an 8 mm cassette tape. About this 8mm cassette tape, static magnetic characteristics,
The still durability property and the friction coefficient on the magnetic layer side were measured. Table 1 shows the results. In addition, each evaluation was performed as follows.

(1) Magnetostatic characteristics Coercive force (Hc) VSM (measured with a vibrating sample magnetometer. Saturation magnetic flux density (Bs) VSM (measured with a vibrating sample magnetometer. (2) Still durability characteristic 8 mm cassette Set the tape on a commercially available 8 mm VTR and output 3 dB under the conditions of 20 ° C / 50% (temperature / humidity).
The still mode time until it decreased was measured. (3) Friction body (diameter 5 m under the condition of friction coefficient 20 ° C / 50% (temperature / humidity)
m, made of stainless steel, surface roughness 0.2 S) 14.3 m
The value when a tension of 20 g was applied so that the wrap angle was 115 ° at a speed of m / sec was measured by a friction coefficient measuring device.

Example 2 An 8 mm cassette tape was manufactured in the same manner as in Example 1. However, the holes formed by ion beam etching were provided at intervals of 500 nm. Others were the same as in Example 1, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

Comparative Example 1 In Example 1, a magnetic layer was formed on the base film which was not subjected to the ion beam etching treatment. Others were the same as in Example 1, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

[0027]

[Table 1]

[0028]

According to the present invention, a magnetic recording medium having improved durability and Bs and a small friction coefficient can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a magnetic recording medium of the present invention.

FIG. 2 is a schematic diagram showing the structure of a conventional vapor deposition type magnetic recording medium.

FIG. 3 is a schematic view of a main part of an apparatus for performing an ion beam etching process on a base film.

FIG. 4 is a schematic view of a main part of an apparatus for manufacturing a magnetic recording medium of the present invention.

[Explanation of symbols]

 1 base film 2 recesses 3 and 3'column of magnetic layer

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H01F 41/20 H01F 41/20 (72) Inventor Hirohide Mizunoya 2606 Akabane, Kaicho, Haga-gun, Tochigi Prefecture Kao Stock Company Research In-house (72) Katsumi Sasaki Katsumi Sasaki 2606 Akabane, Kaicho, Haga-gun, Tochigi Prefecture Kao Institute of Stock Companies (72) Inventor Yuzo Matsuo 2606 Akabane, Kai-cho, Haga-gun, Tochigi Prefecture (72) Inventor Akira Shiga 2606 Akabane, Kaigamachi, Haga-gun, Tochigi Prefecture Kao Institute of Stock Research

Claims (6)

[Claims] 1. A method of manufacturing a magnetic recording medium, comprising the step of depositing a magnetic metal in a vacuum to form a magnetic layer on a base film, wherein the surface of the base film has recesses formed uniformly on the surface. A method of manufacturing a magnetic recording medium, which comprises depositing a magnetic metal. 2. A method of manufacturing a magnetic recording medium, comprising the step of depositing a magnetic metal in a vacuum to form a magnetic layer on a base film, wherein recesses are uniformly formed on the surface of the base film, and then in a vacuum. 2. A method of manufacturing a magnetic recording medium, wherein a magnetic metal is deposited on the surface of the base film to form a magnetic layer. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the recess is formed by ion beam etching. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the ion beam etching is performed with argon ions. 5. The method for manufacturing a magnetic recording medium according to claim 1, wherein the interval between the recesses is 20 to 600 nm. 6. A magnetic recording medium having a base film having concave portions uniformly formed on the surface thereof, and a magnetic layer formed by depositing a magnetic metal on the surface of the base film.