JPH0757254A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium stably maintaining a high S-N ratio by forming a diamondlike hard carbon film on a partially oxidized ferromagnetic metallic thin film, subjecting the surface of the carbon film to plasma treatment with vapor of a lubricant and then vacuum-depositing the lubricant. CONSTITUTION:A partially oxidized ferromagnetic metallic thin film is stuck on a polymer film of a resulting medium to be treated and a diamondlike hard carbon film is formed on the thin film. The temp. condition of the resulting medium to be treated 1 is regulated on a rotating support 2 and the medium 1 is wound around a winding shaft 4. During running on the support 2, the medium 1 is subjected to plasma treatment with vapor generated from a lubricant 7 in an evaporating source vessel 6 by means of a discharge electrode 5 in a high-frequency electric field. A natural lubricant such as carboxylic acid, ester, amide or amine or a synthetic lubricant is used as the lubricant 7. Deposition preventing plates 8, 9 are arranged and an opening 10 for passing vapor is previously pierced in the plate 9. The size and position of the opening 20 and conditions in electric discharge are made optimum at the time of the plasma treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnetic recording medium having a magnetic layer of a ferromagnetic metal thin film suitable for high density magnetic recording and having excellent durability and recording characteristics.

[0002]

2. Description of the Related Art With the progress of information society, the amount of information to be recorded is remarkably increasing, and it is required to increase the recording density of magnetic recording as much as possible. Development of magnetic recording media has been brisk. Although many proposals have been made, the one currently put to practical use is a structure in which the surface of columnar fine particles is coated with an oxide of a ferromagnetic metal itself as disclosed in JP-A-53-58206. It has a well-balanced improvement in recording characteristics and durability, and its constituent elements consist of Co, Ni, and O (JP-A-56-15014), and these magnetic recording layers are formed by oxygen gas. C while intervening
A typical method is electron beam evaporation of o, Co-Ni, and there are some proposals for introducing oxygen, but in the vicinity of the substrate,
A position close to the part for controlling the incident angle is often used (Japanese Patent Laid-Open No. 54-19199, Japanese Patent Laid-Open No. 58-322).
34 publication). Further, while a protective film is being studied in order to improve practical performance, a carbon film with increased hardness (Japanese Patent Application Laid-Open No. 53-143026) and other thin layer inclusions have been used for further improvement. (For example, JP-A-61-2
42323, JP-A-62-167616). These films are applied by a predetermined film thickness after the ferromagnetic metal thin film is formed by vapor deposition by a plasma-applied sputtering method, an ion beam deposition method, a plasma CVD method or the like. Further, a lubricant is arranged by a solution coating method or a vacuum deposition method, and after necessary treatment, it is processed into a tape shape or a disk shape and used.

[0003]

However, in the above-mentioned conventional structure, it is necessary to increase the amount of oxygen introduced to increase the thickness of the surface oxide film, and to increase the hardness of the carbon film and also increase the thickness thereof. There is a large spacing loss,
There is a problem that it is difficult to obtain S / N characteristics sufficient to improve high density recording.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a thin magnetic recording medium having both durability and high output characteristics, which enables narrow track high density recording. And

[0005]

In order to achieve this object, a method of manufacturing a magnetic recording medium according to the present invention comprises forming a diamond-like hard carbon film on a partially oxidized ferromagnetic metal thin film, and forming a plasma of a lubricant vapor on the surface. After the treatment, the lubricant is vacuum-deposited.

[0006]

With this structure, the extremely active lubricant component generated by the plasma on the surface of the diamond-like hard carbon film on the surface of the partially oxidized ferromagnetic metal thin film is enhanced in the binding force and adheres to it. The original lubricant can be strongly bonded, and even if the non-magnetic part that causes space loss is reduced, the durability can be maintained, so durability and high S
It becomes possible to reproducibly manufacture a thin magnetic recording medium having an A / N ratio.

[0007]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a raw material for processing, in which a partially ferromagnetic metal thin film is arranged on a polymer film, and diamond-like hard carbon is formed on it, and 2 is a rotary support and temperature control conditions. Insulation retention and the like can be appropriately selected. Reference numeral 3 is a delivery shaft, and 4 is a winding shaft. Reference numeral 5 is a discharge electrode for performing the plasma treatment of the lubricant vapor, and it is preferable to use a high frequency electric field. Reference numeral 6 is an evaporation source container, and 7 is a naturally occurring lubricant such as carboxylic acid, ester, amide, amine, etc., or a molecularly synthesized lubricant. Reference numerals 8 and 9 denote anti-adhesion plates, and 9 is provided with an opening 10 for passing vapor used for plasma treatment. Reference numeral 11 is a vapor flow used for plasma treatment of the lubricant vapor, and 12 is a vapor flow used for forming a lubricating layer. The heating energy for evaporation is not particularly limited, such as accelerated electron beam and Joule heat. The conditions of the plasma treatment may be optimized by appropriately optimizing the size and position of the opening, the condition of the discharge electrode and the condition of the high frequency electric field.

In order to further clarify the effect of this embodiment, a magnetic recording medium will be made by using the apparatus having the above-mentioned constitution, and the result of the characteristic comparison with that obtained by the conventional method will be described in detail. .

A thickness of 6 μm, 54 in the longitudinal direction and 54 in the width direction, respectively.
Young's modulus of 0,590 [Kg / mm ² ] and average roughness of 3
0Å polyethylene naphthalate film (diameter 150
Å SiO ₂ ultrafine particles with an average density of 20 particles / μm ² resin-fixed coating layer was used in advance) was wound up along a rotary can cooled to 20 ° C. with a diameter of 1 m to collect oxygen. Then, Co was electron beam evaporated to form a magnetic layer of 0.18 μm. The oxygen gas introduction nozzle has a minimum incident angle of 40 degrees, and the mask for determining the incident angle has a 0.8 mm diameter stainless pipe at the tip of which a 0.2 mm diameter hole is arranged at a pitch of 15 mm. / Min It controlled and introduced. The oxide layer on the surface was 110 to 115Å. Then, methane gas was discharged and decomposed by plasma CVD to form a diamond-like hard carbon film of 70Å. The film in this state was used as the raw fabric A, the raw fabric A was divided in the longitudinal direction, and perfluorostearic acid was selected as the lubricant, and the tape formation was advanced so that the example and the conventional example could be compared. In the conventional example, the opening portion 10 of the deposition preventive plate was closed and the lubricant was deposited. In the example, the radiation angle α of the vapor flow shown in FIG. 1 is expressed as positive in the clockwise direction and negative in the counterclockwise direction, and is 60 to 75 degrees for plasma treatment and 30 to 30 for vapor deposition.
A trial was made by combining two conditions of -30 degrees (1a), 60 to 66 degrees for plasma processing, and 20 to -10 degrees (1b) for vapor deposition, and plasma processing conditions. The lubricant was adjusted to have a uniform thickness of 40Å.

Further, a backcoat layer having a thickness of 0.45 μm was formed, and a magnetic tape having a width of 8 mm was manufactured as a prototype and its characteristics were compared. The characteristics of the magnetic tapes are compared with each other by modifying the high-band 8 mm video deck to have a recording wavelength of 0.47 μm and a track pitch of 9
Relative comparison was performed after the recording / reproducing was repeated 130 times at the initial S / N ratio of 40 ° C. and 80% RH in μm.
The length of the magnetic tape was 100 m, 5 rolls were randomly selected, and the average value of 5 rolls was displayed. The still characteristics were compared at 40 ° C. and 5% RH by increasing the tension to 25 g.
The characteristics of the magnetic recording medium according to this example and the characteristics of the magnetic recording medium of the comparative example are shown in comparison with each other (Table 1).

[0012]

[Table 1]

As is clear from Table 1 above, the magnetic recording medium manufactured according to the present example has an excellent effect of achieving durability and high S / N ratio in high density recording in narrow track recording. It is understood that is an excellent manufacturing method.

As described above, according to the manufacturing method of this embodiment, the diamond-like hard carbon film is formed on the partially oxidized ferromagnetic metal thin film, the surface is plasma-treated with the lubricant vapor, and then the lubricant is vacuum-deposited. By doing so, a large number of magnetic recording media can be obtained with good reproducibility, which can stably maintain an excellent S / N ratio in high density recording with a narrowed track even after repeated use.

(Second Embodiment) A second embodiment of the present invention will be described below.

FIG. 2 is a block diagram of the essential parts of a magnetic recording medium manufacturing apparatus used for carrying out the method of manufacturing a magnetic recording medium according to the second embodiment of the present invention. In FIG. 2, the same components as those in FIG. 1 are given the same numbers. Thirteen
Is a laser light source such as carbon dioxide gas or excimer laser,
14 is a laser beam. Reference numeral 15 is a deposition preventive plate. By applying a laser beam at the same time as depositing a lubricant with this device, the effects described below can be obtained.
The vapor deposition area and the laser beam irradiation area do not have to overlap exactly, but the beam needs to be irradiated on the vapor deposition start side. This is because it is presumed that laser activation when the lubricant molecules first contact the diamond-like hard carbon film strongly aids the lubricant deposition.

Further, in order to clarify the effect of this embodiment, a magnetic recording medium is prototyped using the apparatus having the above-mentioned constitution, and the result of the characteristic comparison with that obtained by the conventional method will be described in detail. .

It has a thickness of 5.3 μm, and is in the longitudinal and width directions, respectively.
940, 1050 [Kg / mm²] Young's modulus, average
Polyimide film with a roughness of 25Å (Si with a diameter of 150Å
O₂Average particle density of 20 / μm²Fixed with resin
The coating layer used in advance was used) with a diameter of 1 m.
Wind along the rotary can heated to 200 ℃.
Oxygen is introduced and Co is electron beam evaporated to form a magnetic layer.
0.18μ was formed. The minimum incident angle for the oxygen gas introduction nozzle
Set to 20 degrees and place it directly on the tip of the mask that determines the angle of incidence.
A hole with a diameter of 0.2 mm is made in a stainless pipe with a diameter of 8 mm.
0.8 from the oxygen gas introduction nozzle arranged at 15 mm pitch
It was introduced by controlling to 1 / min. Maximum incident angle is 42 degrees
The surface of the Co-O film with the easy axis of magnetization in the vertical direction
The chemical conversion layer was 120 to 125Å. Methane gas on this
80Å diamond shape by plasma CVD method using
A hard carbon film was formed and a back coat layer was arranged at 0.5 μm.
The raw material B was prepared. Carbon using raw fabric B
Gas laser 1kW / cm ²・ While irradiating for sec
Perfluoroarachidic acid was deposited. Conventional example is laser
The lubricant was deposited without irradiation. 8 mm wide magnets each
Processed into tape. 8 millis modified from these tapes
Digi with 5μ track and bit length of 0.2μ
Tal recording was performed and relative error rates were compared. Durable
After adding 100 pass history at 5 ℃ and 85% RH
The error rate was evaluated. Magnetic recording medium according to this embodiment
The characteristics of the body and the characteristics of the conventional magnetic recording medium are compared in (Table 2).
Is shown.

[0019]

[Table 2]

As is clear from (Table 2), the magnetic recording medium manufactured according to this example has an excellent effect that high-density digital recording under a narrow track condition can be performed with a good error rate. is there.

As described above, according to this embodiment, after the diamond-like hard carbon film is formed on the partially oxidized ferromagnetic metal thin film, the vapor deposition of the lubricant is carried out while the laser beam treatment is performed. The surface becomes extremely active, it adheres strongly to the lubricant, the durability of the lubricating performance is dramatically improved, and the hardness of the hard carbon film is also large because defects near the surface are removed. Therefore, it becomes possible to manufacture a thin magnetic recording medium which can be made thin and has both durability and a high S / N ratio with good reproducibility.

[0022]

As described above, according to the present invention, a diamond-like hard carbon film is formed on a partially oxidized ferromagnetic metal thin film, the surface of the film is plasma-treated with a lubricant vapor, and then the lubricant is vacuum-deposited. Thus, a large number of magnetic recording media can be obtained with good reproducibility, which can stably maintain an excellent S / N ratio in high density recording with a narrowed track even after repeated use.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a processing apparatus used for manufacturing a magnetic recording medium according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of a processing apparatus used for manufacturing a magnetic recording medium according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Processing Fabric 5 Discharge Electrode 7 Lubricant 13 Laser Light Source 14 Laser Beam

Claims (2)

[Claims] 1. A method of manufacturing a magnetic recording medium, comprising forming a diamond-like hard carbon film on a partially oxidized ferromagnetic metal thin film, subjecting the surface to plasma treatment with a lubricant vapor, and then vacuum-depositing the lubricant. . 2. A method of manufacturing a magnetic recording medium, comprising forming a diamond-like hard carbon film on a partially oxidized ferromagnetic metal thin film and then performing a vapor deposition of a lubricant while performing a laser beam treatment.