JPH07114731A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium which produces less bit errors in high-density digital recording by depositing a ferromagnetic metal by evaporation with an electron beam on a moving film, then disposing magnetic fluid in the part where the film is pulled apart by a rotary supporting body. CONSTITUTION:A high-molecular compound film 1 consisting of polyester, etc., is taken up on a film take-up shaft 4 from a film delivery shaft 3 via the rotary supporting body 2 controlled to be at a specified temp. A vapor deposition device is provided with an evaporating source vessel 5, a material 6 for vapor deposition, an accelerated electron beam 7, vapor flow 8, a mask 9, an oxygen introducing nozzle 10 and a glow discharge electrode 11. The ferromagnetic metal is deposited by evaporation with the electron beam on the moving film 1 and thereafter, the magnetic fluid 12 is arranged in the part where the film 1 is pulled apart by the rotary supporting body 2, thereby, the static electricity on the film 1 is discharged through the magnetic fluid 12 or compensated and is apparently neutralized. The film 1 is thus transported under uniform tension. The surface defects, such as wrinkles, are thereby eliminated and the recording medium which produces the less bit errors in high-density digital recording with a narrow track recording is realized.

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).

A conventional method of manufacturing a magnetic recording medium will be described below. FIG. 3 is a configuration diagram of a main part of a vapor deposition apparatus used for manufacturing a conventional magnetic recording medium.

In FIG. 3, 1 is a polymer film such as polyester, 2 is a rotary support controlled to a constant temperature, 3 is a film feeding shaft, 4 is a film winding shaft, 5 is an evaporation source container, and 6 Is a vapor deposition material, 7 is an accelerated electron beam, 8 is a vapor flow, 9 is a mask, 10 is an oxygen introduction nozzle, and 11 is a glow discharge electrode. The method of manufacturing a magnetic recording medium using the apparatus of FIG. 3 is as follows. For example, set polyethylene terephthalate, polyethylene naphthalate, etc. having a grainy surface in a winding system, evacuate and evaporate the vapor deposition material such as Co and Co-Ni by accelerating electron beam to vapor deposit from the tangential direction. The vapor deposition is completed at an incident angle that is blocked by a mask (called the minimum incident angle), oxygen gas is introduced near the minimum incident angle at that time, and the formation of the magnetic recording layer consisting of a partial oxide film is rotatably supported. After being formed on a film that moves along the body, the film is manufactured by being separated from the rotary support, subjected to glow discharge treatment so as to apparently cancel static electricity, and then wound.

[0005]

However, in the above conventional structure, when the glow discharge treatment is strengthened in order to reduce the influence of static electricity by making the film thin, it becomes easy to wrinkle, and the adhesion phenomenon occurs on the smooth surface and the minute portion. However, there is a problem that only high density digital recording can produce a medium having an insufficient error occurrence rate.

The present invention solves the above-mentioned conventional problems, and provides a method of manufacturing a thin magnetic recording medium having both durability and high output characteristics, which enables narrow track high density digital recording. To aim.

[0007]

In order to achieve this object, a method of manufacturing a magnetic recording medium according to the present invention is designed such that a ferromagnetic metal is electron-beam evaporated on a moving film and then the film is separated from a rotary support. , A magnetic fluid is arranged.

[0008]

With this structure, after the magnetic layer is formed, the surface potential of the film charged from the rotary support is reduced by the phenomenon of discharge through the magnetic fluid, and its uniformity can be improved. Since a weak film can be wound with a uniform tension in the width direction, it is not necessary to perform excessive glow discharge treatment, microscopic adhesion phenomenon can be eliminated, and thin magnetic recording media can be manufactured with good reproducibility. .

[0009]

【Example】

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

In FIG. 1, elements having the same configuration as in FIG. 3 are given the same numbers. In FIG. 1, reference numeral 12 denotes a magnetic fluid, and the magnetic fine particles are preferably alloy particles having a particle size of 5 to 30 nm. Since the liquid substance is used in a vacuum, the vapor pressure is low, and when the rotary support is used by cooling It is preferable to design the kinematic viscosity at that temperature to be 5 Cst (20 ° C.) or less. Alloy particle concentration is 10-60%
However, when iron oxide is used instead of alloy particles, it is necessary to adsorb metal ions. Reference numeral 13 is a partition wall for localizing the magnetic fluid to a portion where the film is separated from the rotary support after processing, and is a partition wall composed of the magnet itself or a structure incorporating the magnet. 14 is a free roller.

In order to further clarify the effect of this embodiment, a magnetic recording medium will be concretely manufactured as a prototype, and the results of characteristics comparison with those obtained by the conventional method will be described in detail.

The thickness is 4.1 μm, the Young's modulus is 740,890 [Kg / mm ² ] in the longitudinal direction and the width direction, and the average roughness is 3
0Å polyethylene naphthalate film (diameter 150
Å SiO ₂ ultrafine particles with an average density of 20 / μm ² resin-fixed coating layer was used in advance) was used to wind oxygen along a rotary can of 1 m in diameter cooled to 20 ° C. Then, Co was electron-beam evaporated to form a magnetic layer of 0.18 μm. After vapor deposition, a magnetic fluid was placed in a portion where the film was separated, surrounded by a magnet.

As the magnetic fluid, fine particles of alloys such as iron and cobalt / iron used for magnetic tape are dispersed in natural oil having a low vapor pressure, synthetic oils such as higher alkylbenzene, higher alkylnaphthalene, and polybutene. No particular difference was found in any of the materials. There was no difference in the execution results between the case where a weak glow discharge was applied and the case where it was not applied after contact with the magnetic fluid. Two types of normal glow treatment were confirmed. A hard carbon film having a thickness of 15 nm was formed on each of them, and perfluorostearic acid was applied to have a thickness of 4 nm, and a back coat layer having a thickness of 0.5 μm was provided on the opposite surface.
A magnetic tape having a width of 6.35 mm was evaluated. Evaluation is 8 mm
The video deck was modified for the evaluation of a 6.35 mm wide magnetic tape, and the bit error rate was relatively compared at a bit length of 0.24 μm and a track pitch of 9 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 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).

[0014]

[Table 1]

As is clear from this (Table 1), the magnetic recording medium manufactured according to the present example has wrinkles in the conventional example, the bit error rate varies due to material transfer, and the average value is large. The excellent effect that high-density digital recording with narrow track recording and little bit error can be realized is obtained.

As described above, according to the manufacturing method of this embodiment,
After electron beam evaporation of a ferromagnetic metal on a moving film, by placing a magnetic fluid in the part that separates the film from the rotating support, static electricity on the film is discharged through the magnetic fluid or compensated for apparent appearance. Since they are combined and transported with uniform tension, surface defects such as wrinkles are eliminated even if the thickness becomes thin, and excellent effects such as high density digital recording with narrow bit recording and few bit errors can be obtained.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram of essential parts of a magnetic recording medium manufacturing apparatus 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. Reference numeral 15 is a magnetic fluid, 16 is a magnetic field generator for holding the magnetic fluid, 17 is a plasma generating container, 18 is a discharge electrode, and 19 is a power supply device. The inside of the plasma generating container is evacuated in advance, and the discharge gas can be introduced from the outside (which can be continuously evacuated if necessary). Since the discharge state becomes extremely stable by the above-mentioned structure, the physical properties of the obtained thin film are uniform and good.

The present invention was implemented by the apparatus having the above-mentioned configuration. The present invention will be specifically described in detail by comparing the characteristics of an actually manufactured magnetic recording medium with those of a conventional example and a comparative example.

SiO ₂ having an average particle diameter of 200 Å has an average density of 50 particles / μ ^{2 on} a polyimide film having a thickness of 6 μm (average roughness 20 Å, Young's modulus length 600, width 650 kg / mm ² ).
Was coated and fixed with, and methane gas was used to form a plasma polymerized film thereon with a thickness of 1 nm (2A) and 3 nm (2B). Plasma generating container (internal volume: 0.04m ³ ) and can (diameter 5
0 mm) was set to 2 mm as an initial setting, and an example was prepared in which the magnetic fluid was sealed and a comparative example was prepared without the magnetic fluid. 20 kHz, 1.2 to 2.1 kW for discharge electrode
Was applied, methane gas was introduced at 0.021 / min, and exhaust was performed at 51 / sec only in the example. Co-O perpendicular magnetization films were formed under the following conditions. Co is heated and evaporated by an accelerated electron beam in a magnesia container, and an oxygen gas introduction nozzle is arranged inside the mask having an incident angle in the range of 44 ° to 20 ° and an incident angle of 44 °.
n was introduced and 0.2 μm was vapor-deposited. A diamond-like hard carbon film was formed on the magnetic film by sputtering to 70 Å, and perfluoroarachidic acid was placed on 30 Å,
A magnetic coating tape having a width of 6.35 mm was prepared by providing a back coat layer having a thickness of μm. These tapes were digitally recorded with a 6 μ track and a bit length of 0.2 μ by a test video, and the error rates were compared with each other. The durability was also evaluated by the error rate after adding 100 passes history at 45 ° C. and 85% RH. The characteristics of the magnetic recording medium according to this example and the characteristics of the conventional magnetic recording medium are shown in comparison with each other (Table 2).

[0020]

[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.

Although the embodiment has described the effect of plasma deposition before forming the magnetic layer, the same is remarkable in the case of plasma depositing after forming the magnetic layer to form a carbon film, an oxide film and a plasma polymerized film. It goes without saying that there is a significant improvement effect.

As described above, according to the present embodiment, the magnetic recording medium manufactured by arranging the magnetic fluid in the gap between the plasma generating container and the film during plasma vapor deposition on the moving film has a narrow track condition. There is an excellent effect that high-density digital recording can be performed with a good error rate.

[0024]

As described above, according to the present invention, after the ferromagnetic metal is electron beam evaporated on the moving film, the magnetic fluid is arranged at the portion where the film is separated from the rotary support, so that the film on the film is moved. Since static electricity is discharged through a magnetic fluid or is compensated and apparently neutralized and conveyed with uniform tension, surface defects such as wrinkles are eliminated even if it becomes thin, and bits are used for high density digital recording in narrow track recording. It is possible to obtain an excellent effect that a product with few errors can be realized.

[Brief description of drawings]

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

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

FIG. 3 is an enlarged cross-sectional view of a main part of a vapor deposition apparatus used for manufacturing a conventional magnetic recording medium.

[Explanation of symbols]

 12 magnetic fluid 13 partition wall 15 magnetic fluid 16 magnetic field generator for holding

Claims (2)

[Claims] 1. A method of manufacturing a magnetic recording medium, which comprises subjecting a moving film to electron beam evaporation of a ferromagnetic metal, and then disposing a magnetic fluid in a portion where the film is separated from a rotary support. 2. A method of manufacturing a magnetic recording medium, wherein a magnetic fluid is arranged in a gap between a plasma generating container and the film when plasma-depositing on a film on which a moving magnetic metal is arranged.