JPH11161954A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a magnetic recording medium of a metallic thin film type having a good envelope and cutting and an excellent head touch characteristic. SOLUTION: This process for producing the magnetic recording medium of the metallic thin film type having >=1 layer of magnetic layers consists in evaporating a metallic material to be deposited by evaporation by an electron beam from an electron gun 7 and depositing this material by evaporation on a base 4, thereby executing deposition. In this process for producing the magnetic recording medium of the metallic thin film type, the deposition is executed to satisfy the equation 0.04<=log(300.VL.P)/T<=0.05 when the line speed of the base 4 is defined as VL(m/min), the tension of the base 4 as T(kg/m) and the output of the electron gun 7 as P(kW).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly, to a metal thin film type magnetic recording medium having excellent head touch properties.

[0002]

2. Description of the Related Art A deposition type magnetic recording medium in which a metal thin film is formed on a support by electron beam heating has a high filling ratio of a magnetic substance, and is therefore a coating type magnetic recording medium. Compared to the above, the thin film has a larger saturation magnetization and coercive force, and is used in various application fields as a material suitable for high-density recording.

However, since the metal thin film type magnetic layer does not contain a binder like the coating type magnetic layer, the metal thin film type magnetic layer has high rigidity and is not necessarily sufficient in terms of head touchability. This tendency becomes remarkable when the magnetic layer is thickened.

For example, cupping (curvature in the width direction of the tape) due to different coefficients of thermal expansion and thermal shrinkage and stress remaining in a support made of a polymer film due to the influence of heat received in the manufacturing process of a magnetic recording medium. Occurs. If an appropriate cupping is not secured, it is not possible to perform a normal head touch (head touch property) during the recording and playback processes on the VCR, and noise is generated.
Problems such as out of synchronization occur.

[0005] As described above, there is a demand for a metal thin film type magnetic recording medium having a good envelope and cupping and excellent head touch properties.

Accordingly, it is an object of the present invention to provide a method of manufacturing a metal thin film type magnetic recording medium having a good envelope and cupping and excellent head touch properties.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the line speed and tension of the support and the output of the electron gun when forming a magnetic layer by depositing a deposited metal material on the support. It has been found that the above object can be achieved when there is a certain relationship between.

The present invention has been made based on the above findings. At least one or more magnetic layers formed by evaporating an evaporated metal material by an electron beam from an electron gun, depositing the evaporated metal material on a support, and forming a film. In the method for producing a metal thin-film magnetic recording medium having
_L (m / min), T (kg / m)
And when the output of the electron gun is P (kW), a film is formed so as to satisfy the following expression (1): 0.04 ≦ log (300 · V _L · P) /T≦0.05 (1) And a method of manufacturing a magnetic recording medium.

As described above, in the method for manufacturing a magnetic recording medium of the present invention, the line speed of the support is set at V
_L (m / min) and T (kg /
m), when the output of the electron gun is P (kW), the following formula (1) may be satisfied: 0.04 ≦ log (300 · V _L · P) /T≦0.05 (1) is necessary. The above log (300 V
_{When the} value given by (LP) / T (hereinafter sometimes abbreviated as A) is less than 0.04 or more than 0.05, it is inferior to both the envelope and the cupping, and the head touch property is deteriorated. I do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the drawings. In the method for manufacturing a magnetic recording medium of the present invention, the magnetic layer is formed by a vacuum evaporation method. The vapor deposition apparatus used here is not particularly limited, and a conventionally known apparatus can be used. However, it is preferably produced by a continuous vacuum vapor deposition apparatus having oblique vapor deposition means as shown in FIG.

In the apparatus shown in FIG. 1, a support 4 is conveyed from an unwinding roll 2 to a winding roll 3 via a cooling can roll 5 in a chamber 1 to be evacuated. A crucible 6 is disposed below the cooling can roll 5, and an electron beam is emitted from the electron gun 7 to the deposited metal material accommodated therein to evaporate the deposited metal material, and is supported on the cooling can roll 15. An evaporated metal film is deposited on the body 4. Thus, at least one or more magnetic layers are formed on the support.

Here, a shielding plate 8 is provided in order to limit a region where the vapor of the vapor-deposited metal material is deposited. Reference numeral 9 denotes a nozzle for supplying an oxidizing gas at the time of vapor deposition. By introducing an oxidizing gas such as oxygen, the coercive force is increased and the C / N characteristics are improved.

Here, the line speed of the support 4 (V
_L ) is 30 to 120 m / min, tension (T) is 0.25
It is desirably about 0.35 kg / m. The output (P) of the electron gun is desirably 70 to 300 kW.

In the present invention, as described above, it is necessary to satisfy the following expression (1): 0.04 ≦ log (300 · V _L · P) /T≦0.05 (1) . In order to set the value given by the above equation (1) in such a range, the line speed (V _L ) and tension (T) of the support 4 and the output (P) of the electron gun in the above range are appropriately adjusted. It is obtained by adjusting.

Here, the tension (T) of the support 4 is obtained by averaging the forces (F) applied to the unwinding portion and the rewinding portion before and after the can roll, and dividing the result by the width (W) of the support. That is, T (kg / m) = F (kg) / W (m).

In the method of manufacturing a magnetic recording medium according to the present invention, it is desirable that the line speed (V _L ) of the support and the output (P) of the electron gun satisfy the following expression. (−0.0009P ² + 0.6179P−5.315
8) ≦ V _L ≦ (−0.0018P ² + 1.2357P−)
10.632)

FIG. 2 shows a preferable range of the line speed (V _L ) of the support and the output (P) of the electron gun. In FIG. 2, a hatched portion is a preferable range. By setting the shaded region, an appropriate film thickness can be easily obtained.

Examples of the nonmagnetic material constituting the support include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polycyclohexylene dimethylene terephthalate and polyethylene bisphenoxycarboxylate; polyethylene, polypropylene and the like. Polyolefins; cellulose derivatives such as cellulose acetate butyrate and cellulose acetate propionate; vinyl resins such as polyvinyl chloride and polyvinylidene chloride; and plastic materials such as polyamide and polycarbonate. Among them, polyethylene terephthalate is particularly preferably used. The form may be any of a film, tape, sheet, disk, drum and the like. The support composed of these materials may be subjected to uniaxial or biaxial stretching treatment, corona discharge treatment, plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment, bombardment treatment, or the like, if necessary. Good. The preferred thickness of the support is 1
３００300 μm.

The number of layers is not particularly limited as long as the magnetic layer formed as described above is composed of one or more layers.
As a material of the deposited metal film forming the magnetic layer, for example, in addition to metals such as Fe, Co, and Ni, a Co-Ni alloy,
Co-Pt alloy, Co-Ni-Pt alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-C
An o-B alloy, a Co-Ni-Fe-B alloy, a Co-Cr alloy, or the like is used. Further, Fe-N, Fe-NO, F
e-C, Fe-CO, etc. are also used. Note that it is preferable that an oxidizing gas be supplied at the time of forming the above-described deposited metal film to form a protective layer made of an oxide film on the surface of the deposited metal film. Note that, as the oxidizing gas, for example, oxygen, air, or the like is used, but oxygen is preferable.

In the case where the magnetic layer has a plurality of layers, the material constituting each deposited metal film may be the same or different. Preferably, the material forming each of the above-described deposited metal films is the same.

The total thickness of the magnetic layer is 0.1 to
0.5 μm, preferably 0.12 to 0.3 μm
m is more preferable. If the thickness is less than 0.1 μm, the durability of the magnetic layer may not be sufficient.
If it exceeds 5 μm, self-demagnetization may increase.
It is preferable to be within the above range.

Prior to the formation of the magnetic layer, an undercoat layer for improving the adhesion of the magnetic layer may be provided on the surface of the support. Such an undercoat layer has a thickness of, for example, 0.02 including particles such as SiO _2.
It consists of a coating of 5 to 0.5 μm. By using such an undercoat layer, the surface of the support is appropriately roughened,
For example, it is possible to improve the adhesion of the magnetic layer formed by the oblique vapor deposition method and to improve the running property by making the surface roughness of the magnetic layer appropriate.

As described above, the magnetic recording medium obtained by the manufacturing method of the present invention has the above-described support and a magnetic layer formed on the support and composed of one or more deposited metal films.
That is, in the magnetic recording medium of the present invention, a magnetic layer may be provided directly on the support, or an arbitrary layer (for example, the above-described undercoat layer) may be provided between the support and the magnetic layer. ) May be interposed. Furthermore, in the magnetic recording medium of the present invention, a protective layer for protecting the magnetic layer may be provided on the magnetic layer, or a lubricant layer for improving durability may be provided on the protective layer. Good. Hereinafter, such a protective layer and a lubricant layer will be described below.

The above-mentioned protective layer is formed on the above-mentioned magnetic layer, generally in a vacuum, by carbon or carbide, nitride, especially diamond-like carbon, diamond, boron carbide, silicon carbide, boron nitride, silicon nitride, silicon oxide, aluminum oxide, etc. Is formed by forming a film. The protective layer may be formed by any of a chemical vapor deposition (CVD) method and a PVD method. In the CVD method, an ECR (Electron Cyclotron Resonance) method using a microwave and a method using a high frequency (RF) are particularly effective. CVD
When forming the protective layer by a method, any of gaseous, liquid and solid materials may be used.

The protective layer is preferably made of diamond-like carbon. In this case, when forming a protective layer made of diamond-like carbon using a gaseous raw material, a mixed gas of methane and argon, a mixed gas of ethane and hydrogen, or a mixed gas of methane and hydrogen as the gaseous raw material is used. It is preferable to use a mixed gas of Also,
When the protective layer made of diamond-like carbon is formed using a liquid material, it is preferable to use an alcohol or an unsaturated hydrocarbon as the liquid material. Further, when a protective layer made of diamond-like carbon is formed using a solid material, it is preferable to use naphthalene or higher paraffin as the solid material.
In this case, the solid may be heated or ultrasonic waves may be applied.

The PVD method includes a thermal evaporation method, a sputtering method, an ion plating method and the like, and any of them can be used. Of these methods, the sputtering method is particularly effective. When a protective layer made of diamond-like carbon is formed by a sputtering method, it is preferable to perform sputtering in a mixed gas of methane and argon or a mixed gas of methane and hydrogen using a graphite target. When a protective layer made of silicon nitride is formed by a sputtering method, a mixed gas of argon and nitrogen, a mixed gas of argon and ammonia, a nitrogen gas, an ammonia gas, or a mixture of ammonia and monosilane (silicon target) are used. It is preferable to perform sputtering in a mixed gas with SiH ₄ ). In the case where a protective layer made of aluminum oxide is formed by a sputtering method, it is preferable to perform sputtering in a mixed gas of argon and oxygen using an aluminum target.

The degree of vacuum when forming the protective layer is preferably about 10 ^-1 to 10 ^-5 Torr in the case of the CVD method, and is preferably about 10 ^-4 to 10 ^-7 Torr in the case of the PVD method. . The thickness of the protective layer is not particularly limited, but is preferably 1 to 30 nm, and more preferably 3 to 15 nm.

Next, the lubricant layer will be described. The lubricant layer is provided with a sprayer equipped with an ultrasonic oscillator (hereinafter, referred to as a sprayer).
It is preferable that the lubricant is formed by spraying a lubricant onto the magnetic layer (when the protective layer is formed on the magnetic layer, on the protective layer) using an “ultrasonic sprayer”. More specifically, the ultrasonic atomizer includes a supply unit for the lubricant, a unit (ultrasonic oscillator) for applying an ultrasonic wave to the lubricant supplied from the supply unit to atomize the lubricant, and And a nozzle for spraying the lubricant. Also,
A nozzle type spraying device may be used. As the nozzle type spraying device, a device generally called a one-fluid nozzle can be used.

Since the lubricant can be sprayed as fine particles using an ultrasonic atomizer, the lubricant layer is weak at high temperatures (200 ° C. or higher) and has a low vapor pressure. It is possible to spray the formed fluorine-based lubricant such as perfluoropolyether in a vacuum. In addition, as in the conventional method, in the atmosphere,
The lubricant may be applied using a gravure method, a reverse method, or a die coating method.

As the above perfluoropolyether,
Those having a molecular weight of 2,000 to 5,000 are suitable. For example, "FOMBLIN Z DIAC" (carboxyl group-modified, manufactured by Audimont Co., Ltd.), "FOMBLIN Z DOL" (alcohol-modified,
Audimont Co., Ltd.] can be used. Since these have a hydroxyl group or a carboxyl group at the terminal, they can enhance the binding between the lubricant and the magnetic layer, and are therefore preferably used.

In addition to the above lubricants, benzene rings,
A fluorine-based lubricant containing a double bond, a branched chain, or the like, a fatty acid-based lubricant, and other lubricants can also be used. Of these, the above-mentioned fluorine-based lubricants are preferably used because they improve not only durability but also corrosion resistance as compared with fatty acid-based lubricants.

In spraying the lubricant, the lubricant is mixed with a fluorinated inert solvent (for example, a perfluorocarbon such as "Fluorinert" manufactured by Sumitomo 3M Ltd.)
About 0.001 to 10% by weight dissolved in an appropriate solvent such as an aromatic hydrocarbon solvent such as "Garden" manufactured by Ausimont Co., Ltd.), an aromatic hydrocarbon solvent such as toluene, an alcohol solvent, or a ketone solvent. , Especially 0.02 to 2.
It is preferably used as a 0% by weight solution. When perfluoropolyether is used as the lubricant, perfluorocarbon can be used as the solvent, and the concentration in that case is about 0.001 to 1.0% by weight, particularly 0.05 to 1.0% by weight.
0.2% by weight is preferred. The spray amount of the lubricant may be appropriately determined in consideration of the use of the magnetic recording medium, the type of the lubricant, and the like.
It is preferable to adjust so as to be about 5 to 20 nm.

Further, in the magnetic recording medium of the present invention, a back coat layer may be formed on the surface of the support 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 an appropriate solvent, or by depositing a metal or metalloid by physical vapor deposition (PVD), particularly thermal evaporation or sputtering. It may be formed by vapor deposition.

When the back coat layer is formed by coating, carbon black having a particle size of 10 to 100 nm is used.
Dispersed in a binder such as vinyl chloride, urethane or nitrified cotton, and the thickness after drying is preferably 0.4 to 1.0 by a gravure method, a reverse method or a die coating method.
Apply to a thickness of μm.

When the back coat layer is formed by vapor deposition, it is preferable to use aluminum or silicon as the metal or metalloid material. In this case, the thickness of the back coat layer is preferably 0.05 to 1.0.
μm.

A top coat layer may be provided on the back coat layer for the purpose of further improving runnability, durability and the like.

FIG. 3 is a schematic diagram showing the structure of a magnetic recording medium obtained by the manufacturing method of the present invention having such a structure.
Shown in The magnetic recording medium 11 shown in FIG. 3 includes a nonmagnetic support 12 and a magnetic layer 13 provided on one surface of the support 12.
And a back coat layer 16 arbitrarily provided on the other surface side of the support 12. Then, the magnetic layer 13
A protective layer 14 and a lubricant layer 15 are optionally provided thereon.
In FIG. 1, the magnetic layer 13 has a one-layer structure, but may have a one-layer structure or a two-layer structure or more.

The magnetic recording medium obtained by the present invention is used in the form of tapes, disks, drums, sheets, and other forms, and is particularly preferably used in the form of magnetic tapes, and particularly, recording by a ring head. -It is suitably used for reproduction.

[0039]

EXAMPLES Hereinafter, the magnetic recording medium of the present invention will be described in more detail with reference to examples. Note that such examples do not limit the scope of the present invention in any way.

Example 1 A magnetic layer was formed by the vacuum evaporation apparatus shown in FIG. That is, the vacuum chamber 1 is 2 ×
The vessel was evacuated to 10 ^-5 Torr, and Co was used as a metal deposition material.
I put it in. An electron beam was irradiated from the electron gun 7 at an output of 75 kW to form a vapor deposition atmosphere. A polyethylene terephthalate (PET) film 4 having a thickness of 6.3 μm was run from the unwinding roll 2 to the winding roll 3 at 37 m / min. The film tension at this time was 0.25 kg /
m. And coefficient A was 0.042. At the same time, oxygen gas is supplied from the oxygen nozzle 9 for 230 S.
CCM was introduced and the magnetic layer was formed to have a thickness of 180 nm.

Thereafter, a protective layer (DLC film) of 10 nm is formed on the magnetic layer using benzene as a raw material gas by using an ECR-CVD apparatus. A back coat paint mixed with black was applied (gravure coat) to a dry thickness of 0.5 μm and dried to form a back coat layer. Next, a fluorine-based lubricant was applied to a thickness of 2 nm on the protective layer (DLC film) to form a lubricant layer.

Next, the PET film was slit to obtain a magnetic tape, and the obtained magnetic tape was loaded into a DVC cassette case to obtain a DVC cassette.

[Examples 2 to 16 and Comparative Examples 1 to 7] As conditions for forming the magnetic layer, the line speed (V _L ), tension (T), output (P) of the electron gun and log (300 · V
_L / P) / T and the thickness of the magnetic layer are as shown in Table 1, and a magnetic tape was obtained in the same manner as in Example 1 except that the magnetic layer was formed. And

<Evaluation of Characteristics> Examples 1 to 16 and Comparative Example 1
Envelopes and cuppings of the magnetic tapes obtained in Nos. 1 to 7 were measured by the following methods according to the following methods. The results are shown in Table 1.

(Envelope) A commercially available DVC camera (S
A model VX-1000 (manufactured by ONY) was modified, and the output was connected to an oscilloscope to observe the envelope.
Here, the maximum value a of the envelope (output waveform)
The ratio (b / a) of the minimum value b with respect to is expressed in% (FIG. 4).
reference). An evaluation standard exceeding 85% was acceptable.

(Cupping) The magnetic tape loaded in the DVC cassette was pulled out, cut out into a length of 30 cm, and placed on a flat plate. As shown in FIG. 5, the flying height (α) from the plane was determined, and this was calculated as the amount of cupping. And the curvature (%) was calculated. The smaller the amount of cupping, the better, and less than 10% was acceptable as an evaluation standard.

[0047]

[Table 1]

As is clear from the results in Table 1, Examples 1 to
It can be seen that the magnetic tape obtained in No. 14 has better envelope and cupping than the magnetic tapes obtained in Comparative Examples 1 to 7, and has excellent head touch properties.

[0049]

As described in detail above, the production method of the present invention has a good envelope and cupping,
A metal thin film type magnetic recording medium having excellent head touch properties can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a continuous vacuum deposition apparatus used in a production method of the present invention.

FIG. 2 is a graph showing a preferable range of a line speed (V _L ) of a support and an output (P) of an electron gun in the manufacturing method of the present invention.

FIG. 3 is a schematic diagram showing an example of a structure of a magnetic recording medium obtained by a manufacturing method of the present invention.

FIG. 4 is a schematic diagram showing a method for measuring an envelope.

FIG. 5 is a schematic diagram showing a method for measuring cupping.

[Explanation of symbols]

 Reference Signs List 1 chamber 2 unwind roll 3 take-up roll 4 support 5 cooling can roll 6 crucible 7 electron gun

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Miyamura 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Prefecture Inside the Kao Corporation Research Institute

Claims (2)

[Claims] 1. Production of a metal thin film type magnetic recording medium having at least one or more magnetic layers formed by evaporating a vapor-deposited metal material by an electron beam from an electron gun, evaporating the metal material on a support, and forming a film. In the method, the line speed of the support is V _L (m / min), the tension of the support is T (kg / m), and the output of the electron gun is P.
Magnetic recording characterized by satisfying the following expression (1): 0.04 ≦ log (300 · V _L · P) /T≦0.05 (1) The method of manufacturing the medium. 2. The method according to claim 1, wherein the line speed (V _L ) of the support and the output (P) of the electron gun satisfy the following expression. (−0.0009P ² + 0.6179P−5.315
8) ≦ V _L ≦ (−0.0018P ² + 1.2357P−)
10.632)