JP2833444B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art With the development of the information-oriented society, the amount of information to be recorded has increased remarkably, and it has been required to increase the recording density of magnetic recording as much as possible. The development of magnetic recording media has become active. Although many proposals have been made, the one currently in practical use has 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 improved recording characteristics and durability in a well-balanced manner. The constituent elements are composed of Co, Ni, and O (Japanese Patent Application Laid-Open No. 56-15014), and these magnetic recording layers are formed by oxygen gas. C with intervening
The method of e-beam evaporation of o, Co-Ni is typical, and there are several proposals for the introduction of oxygen.
A position close to the part for controlling the incident angle is often used (Japanese Patent Application Laid-Open Nos. 54-19199 and 58-322).
No. 34).

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

In FIG. 3, 1 is a polymer film of polyester or the like, 2 is a rotary support controlled at a constant temperature, 3 is a film feed shaft, 4 is a film winding shaft, 5 is an evaporation source container, 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. A method of manufacturing a magnetic recording medium using the apparatus of FIG. 3 is as follows. For example, polyethylene terephthalate, polyethylene naphthalate, etc. having a granular surface are set in a winding system, evacuated, and a vapor deposition material such as Co or Co-Ni is heated and evaporated by an accelerated electron beam, and is vapor-deposited from a tangential direction. The vapor deposition is completed at the angle of incidence (called the minimum angle of incidence) that is cut off by the mask. At that time, oxygen gas is introduced near the minimum angle of incidence, and the formation of the magnetic recording layer consisting of the partial oxide film is supported by rotation. After the film is moved along the body, the film is separated from the rotating support, is subjected to a glow discharge treatment so as to apparently cancel static electricity, and is wound.

[0005]

However, in the above-mentioned conventional structure, when the glow discharge treatment is strengthened to reduce the influence of static electricity by reducing the thickness of the film and making it wrinkle, the adhesion phenomenon occurs between the smooth surface and the minute portion. As a result, there has been a problem that only a medium having an insufficient error rate can be manufactured in high-density digital recording.

An object of the present invention is to provide a method for manufacturing a thin magnetic recording medium having both durability and high output characteristics, which enables high-density narrow-track digital recording. Aim.

[0007]

In order to achieve the above object, a method of manufacturing a magnetic recording medium according to the present invention comprises the steps of: depositing a ferromagnetic metal on a moving film by an electron beam; , And a magnetic fluid.

[0008]

With this structure, after the formation of the magnetic layer, the surface potential of the film charged from the rotating support is reduced by the discharge phenomenon through the magnetic fluid, and the 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 an excessive glow discharge treatment, and a microscopic adhesion phenomenon can be eliminated, so that a thin magnetic recording medium 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, the same elements as those shown in FIG. 3 have the same reference numerals. In FIG. 1, reference numeral 12 denotes a magnetic fluid, and magnetic fine particles are preferably alloy particles having a particle diameter of 5 to 30 nm. Since the liquid substance is used in a vacuum, the liquid substance has a low vapor pressure and is used when the rotating support is cooled and used. 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 denotes a partition wall for localizing the magnetic fluid to a portion where the film is separated from the rotating support after the processing is completed, and is composed of a magnet itself or a structure having a built-in magnet. 14 is a free roller.

Hereinafter, in order to clarify the effect of the present embodiment, a magnetic recording medium is experimentally manufactured, and the results of comparison of characteristics with those obtained by a conventional method will be described in detail.

The thickness is 4.1 μm, the Young's modulus is 740 and 890 [Kg / mm ² ] in the longitudinal and width directions, respectively, and the average roughness is 3
0Å polyethylene naphthalate film (diameter 150
( ₂ ) Ultrafine particles of SiO ₂ (preliminarily provided with a coating layer having a resin fixed at an average density of 20 / μm ² ) were wound along a 1 m diameter rotating can cooled at 20 ° C. to remove oxygen. Then, Co was deposited by electron beam evaporation to form a magnetic layer of 0.18 μm. After vapor deposition, a magnetic fluid was placed around the part where the film was separated by a magnet.

The magnetic fluid used was a dispersion of fine particles of an alloy of iron, cobalt, iron or the like used for a magnetic tape in a natural oil having a low vapor pressure or in a higher oil such as a higher alkylbenzene, a higher alkylnaphthalene or a polybutene which is a synthetic oil. No difference was found in any of the materials. After touching the magnetic fluid, there was no difference in the execution results between the case where a weak glow discharge was applied and the case where the weak glow discharge was not applied. Two types of normal glow processing were confirmed. A hard carbon film having a thickness of 15 nm is formed on each of them by a plasma CVD method, 4 nm of perfluorostearic acid is further applied, and a 0.5 μm-thick back coat layer is provided on the opposite surface.
A magnetic tape having a width of 6.35 mm was evaluated. Evaluation is 8mm
The VCR was modified for evaluation of a 6.35 mm-wide magnetic tape, and the bit length was 0.24 μm and the track pitch was 9 μm. The length of the magnetic tape was 100 m, and five volumes were randomly selected and displayed as an average value of five volumes. Table 1 shows the characteristics of the magnetic recording medium according to the present embodiment and the characteristics of the magnetic recording medium of the comparative example.

[0014]

[Table 1]

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

As described above, according to the manufacturing method of this embodiment,
After depositing the ferromagnetic metal on the moving film by electron beam evaporation, the magnetic fluid is placed on the part that separates the film from the rotating support, so that the static electricity on the film is discharged through the magnetic fluid or compensated, and apparently medium Since the sheets are summed and conveyed with a uniform tension, an excellent effect of eliminating surface defects such as wrinkles even when thinned and achieving high-density digital recording in narrow track recording with few bit errors can be obtained.

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

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

On a polyimide film having a thickness of 6 μm (average roughness: 20 °, Young's modulus: 600, width: 650 Kg / mm ² ), SiO ₂ having an average particle diameter of 200 ° was applied at an average density of 50 / μ ^2.
And a plasma-polymerized film was formed thereon by using methane gas at 1 nm (2A) and 3 nm (2B). Plasma generation vessel (internal volume; 0.04 m ³ ) and can (diameter 5)
(0 cm) was set to 2 mm as an initial setting and sealed with a magnetic fluid, and a comparative example in which a magnetic fluid was not provided and a prototype was prepared. 20 kHz, 1.2 to 2.1 kW for the discharge electrode
Was applied, methane gas was introduced at a rate of 0.021 / min, and exhaust was performed at a rate of 51 / sec only in the examples. A Co-O perpendicular magnetization film was formed under the following conditions. Co is heated and evaporated by an accelerating electron beam in a magnesia container, and an oxygen gas introduction nozzle is arranged inside a mask having an incident angle of 44 degrees from an incident angle of 44 to 20 degrees, and 0.71 / mi.
n was introduced and 0.2 μm was deposited. A diamond-like hard carbon film was formed on the magnetic film by sputtering at 70 °, and perfluoroarachinic acid was distributed at 30 ° to obtain
A backcoat layer of μm was arranged and processed into magnetic tapes each having a width of 6.35 mm. These tapes were digitally recorded on a 6 μ track and a bit length of 0.2 μ with a test video, and the error rates were compared relatively. The durability was also evaluated based on the error rate after adding 100 passes at 45 ° C. and 85% RH. Table 2 shows the characteristics of the magnetic recording medium according to the present embodiment and those of the conventional magnetic recording medium.

[0020]

[Table 2]

As is apparent from Table 2, the magnetic recording medium manufactured according to the present embodiment 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 case where plasma deposition is performed after the formation of the magnetic layer to form a carbon film, an oxide film, and a plasma polymerized film is also remarkable. It goes without saying that there is a significant improvement effect.

As described above, according to this embodiment, the magnetic recording medium manufactured by disposing the magnetic fluid in the gap between the plasma generating container and the film when performing the plasma deposition on the moving film can be used in 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, a ferromagnetic metal is deposited on a moving film by electron beam evaporation, and then a magnetic fluid is disposed on a portion where the film is separated from the rotating support. Static electricity is discharged through the magnetic fluid, or compensated and apparently neutralized and transported with uniform tension.Therefore, even when thinner, surface defects such as wrinkles are eliminated and high-density digital recording with narrow track recording is performed. An excellent effect that an error-free one can be realized is obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged 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 a main 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 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)

(57) [Claims] 1. A method for manufacturing a magnetic recording medium, comprising: depositing a ferromagnetic metal on a moving film by electron beam, and then disposing a magnetic fluid at a portion where the film is separated from a rotating support. 2. A method of manufacturing a magnetic recording medium, comprising: disposing a magnetic fluid in a gap between a plasma generating container and a film when performing plasma deposition on a film on which a moving magnetic metal is disposed.