JPH01107319A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics and weatherability by forming a magnetic layer by an electron beam radiated from a hollow cathode electron gun. CONSTITUTION:An evaporation source 5 for a magnetic material or alloy is installed to face the surface of a base material 3 and the hollow cathode electron gun 4 is disposed toward the evaporation source, then the magnetic layer is formed by a hollow cathode discharge method. Namely, the atoms or molecules (evaporated metal 51) of the ferromagnetic metal (alloy) evaporated from the evaporation source 5 by the electron beam radiated from the electron gun 4 advance toward the surface of the base material 3 and are ionized by colliding against the electrons 46 during the process of such advance. The evaporated metal 52 which is ionized is accelerated by the electric field formed near the base material 3 toward the surface of the base material and is securely stuck to the surface of the base material, by which said metal is deposited on the base material and a magnetic layer is formed. The magnetic characteristics such as coercive force and squareness ratio as well as weatherability (corrosion resistance) are thereby improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing magnetic recording media such as magnetic tapes and magnetic disks, and in particular to a method for forming a ferromagnetic metal film with excellent characteristics on the surface of a substrate. It is something.

(Prior art) This type of magnetic recording medium has a ferromagnetic metal film provided on the surface of, for example, a polyester base material, and the formation of the ferromagnetic metal film involves the following steps:
Conventionally, vacuum evaporation, sputtering, or ion blating methods have been used (e.g.,
-128027 [G11B5/84]).

(Problem to be solved) Vacuum deposition has the advantage of a simple manufacturing process and a high deposition rate, but it does not provide sufficient adhesion strength between the base material and the magnetic layer. There's a problem. In addition, the conventional sputtering method and ion blating method eliminate the drawbacks of the vacuum evaporation method, but in order to stabilize the high frequency plasma or glow discharge, an inert gas is sealed in the discharge vessel. It is necessary to form a film in a low vacuum atmosphere of about 10-3 to 10-" Torr. Therefore, the inert gas becomes an impurity and the evaporated metal emitted from the evaporation source to the surface of the base material. As a result, magnetic recording media manufactured by these methods have problems in terms of magnetic properties such as coercive force and squareness ratio, or weather resistance (corrosion resistance). there were.

(Means for Solving the Problems) An object of the present invention is to solve the above problems and provide a method for manufacturing a magnetic recording medium that provides better magnetic properties and weather resistance than conventional methods.

The inventors of the present invention have repeatedly conducted research to achieve the above object, and have discovered the hollow cathode discharge method, which has been used exclusively for forming carbide and nitride films (for example, in the "Nikkei New Materials" September 20, 1985 issue). , pzt~24) was found to be effective in forming a ferromagnetic metal film, leading to the completion of the present invention.

In the method for manufacturing a magnetic recording medium according to the present invention, an evaporation source (5) of a magnetic material or alloy is installed opposite to the surface of a base material (3), and a hollow cathode electron gun is directed toward the evaporation source. (4), and a magnetic layer is formed by a hollow cathode discharge method.

(Function) As shown in FIG. 2, the electron beam emitted from the electron gun (4) is emitted toward the evaporation source and heats the evaporation source. As a result, ferromagnetic gold B (
Atoms or molecules of the metal alloy (hereinafter referred to as evaporated metal (51)) pass through the flow of the electron beam and proceed toward the surface of the base material (3). The evaporated metal (51) collides with the electrons (46) as it travels through the electron beam and is ionized. The ionized evaporated metal (52) is accelerated toward the surface of the base material (3) by an electric field formed near the base material (3),
It firmly adheres to the surface of the base material and is deposited to form a magnetic layer.

(Effects of the Invention) Since the method for manufacturing a magnetic recording medium according to the present invention applies the hollow cathode discharge method, the degree of vacuum in the vacuum container (1) can be increased to about 10"" 10-5 Torr, Therefore, the amount of ions of the inert gas introduced into the vacuum container (1) from the hollow cathode of the electron gun (4) is very small compared to the amount of ions of the evaporated metal. As a result, the conventional problems caused by inert gas are solved, and a magnetic layer with excellent characteristics is formed.

(Example) FIG. 1 shows an example in which the method for manufacturing a magnetic recording medium according to the present invention was applied to manufacturing a magnetic tape for an 8 mm VTR.

An exhaust device (8) is connected to the vacuum container (1), and the degree of vacuum inside the container is set at 10-4 to 10-5 Torr.

A supply roll (21) and a take-up roll (24) wound with a tape base material (3) of polyethylene terephthalate having a thickness of 9 μm are provided inside the vacuum container (1), and the base material (3) between the two rolls is disposed. ) is a pair of guide rolls (22) (23
), the cooling can with a diameter of 400 mm (2)
is wrapped around the circumferential surface over a predetermined angular range.

The moving speed of the base material (3) is set to 10°, On/win.

Below the cooling can (2) is Co, which serves as an evaporation source (5).
and Ni alloy (Co: 80wt%, Ni: 20wt%
%) is placed in the crucible (7).

A hollow cathode electron gun (4) is placed facing the evaporation source (5). A gas is supplied to the electron gun (4) from an Ar gas introduction tube (41).

Along the circumferential surface of the cooling can (2), a mask (9) for blocking evaporated metal is placed at a position facing the evaporation source (5), and a mask (9) for blocking evaporated metal and accelerating the evaporated metal and metal ions to adhere to the base material (3). An accelerating electrode (6) for accelerating is arranged in parallel.

A DC voltage of -1.5 kV is applied to the accelerating electrode (6).

The hollow cathode electron gun (4) has an insulator (
An anode (44) having a plurality of through holes is arranged through the hollow cathode (43), and Ar gas is introduced into the hollow cathode (42) from the Ar gas supply section (45).
42) and the anode (44). Hollow cathode (42) and anode (44)
The partial pressure of Ar gas between is approximately 0. It is adjusted so that it becomes ITorr.

In the hollow cathode electron gun (4), once an arc discharge occurs, ions are extracted from the plasma of the arc discharge and collide with the hollow cathode (42). This heats the hollow cathode (42) and releases a large amount of electrons toward the anode (44) as shown.

The electrons (46) that have passed through the through hole of the anode (44) are deflected and focused by a magnet (not shown), and become an electron beam as shown in FIG. 2, which irradiates the evaporation source (5).

As mentioned above, the evaporated metal (51) from the evaporation source (5) is ionized by passing through the electron beam, and the ionized evaporated metal (52) is accelerated by the accelerating electrode (6) and is attached to the base material ( 3) will be obliquely deposited on the surface as shown in the figure.

Note that it is also possible to further increase the adhesion force to the base material (3) by adjusting the potential of the accelerating electrode (6) and setting the collision energy of the evaporated metal to an appropriate level.

In the manufacturing method according to the present invention, since the container in which vapor deposition is performed is set at a high vacuum degree of 10-4 to 10-5 TorrO, the amount of ions in the inert gas is lower than that of conventional sputtering or ion blating methods. Therefore, magnetic properties such as coercive force and squareness ratio, and weather resistance (corrosion resistance) are significantly improved.

In order to compare the performance of the magnetic tape manufactured using the apparatus shown in Figure 1 and the magnetic tape manufactured using the conventional vacuum evaporation method, the comparison was made in a harsh atmosphere with an air temperature of 60°C and a relative humidity of 90%. An experiment was conducted to examine the relationship between the elapsed time and saturation magnetization, which indicates the degree of corrosion progress, by leaving two magnetic tapes undisturbed.

The results are shown in FIG.

In FIG. 4, the horizontal axis shows the standing time, and the vertical axis shows the saturation magnetization ratio, that is, the ratio of the saturation magnetization at an arbitrary time to the saturation magnetization when the standing time is O.

The solid line in the figure shows the measurement result of the magnetic tape according to the manufacturing method of the present invention, and the broken line shows the measurement result of the magnetic tape according to the conventional method.

From this result, it is clear that the present invention improves the corrosion resistance of the magnetic tape.

Furthermore, an experiment was conducted to examine the decrease in reproduction output when still images are repeatedly reproduced on a magnetic tape for an 8 mm VTR. From this result, it was found that the life span from the start of the experiment until the playback output decreases by 3 dB according to the present invention is more than 10 times longer than that of the conventional method. This means that the adhesion strength between the tape base material and the magnetic layer has increased significantly.

Incidentally, the present invention can also be implemented in the manufacture of magnetic disks.

It goes without saying that the configuration of each part of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the claims.

For example, accelerated type! Instead of providing (6), a negative potential may be applied to the substrate itself to accelerate the ionized vaporized metal.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a manufacturing apparatus that implements the method for manufacturing a magnetic recording medium according to the present invention, FIG. 2 is a diagram explaining the principle of the hollow cathode discharge method, and third is a schematic diagram of a hollow cathode electron gun. FIG. 4, an enlarged cross-sectional view showing the structure, is a graph showing the degree of progress of corrosion. (1)...Vacuum container (2)...Cooling can (3)...Base material (5)...Evaporation source (4
)... Hollow cathode electron gun procedure amendment [Rules 1. Indication of the case: Japanese Patent Application No. 1983-2660532, Title of the invention: Method for manufacturing magnetic recording media 3, Person making the amendment
Applicant (188) Sanyo Electric Co., Ltd. 5. Date of procedural amendment order: January 26, 1985 (shipment date) 6. Brief description of drawings in the specification subject to amendment

Claims (1)

[Claims] [1] In a method for manufacturing a magnetic recording medium by forming a magnetic layer made of a ferromagnetic material or alloy on the surface of a polymeric base material (3), the vacuum container (1) Inside, an evaporation source of a ferromagnetic material or alloy is installed facing the surface of the base material (3), and a hollow cathode electron gun (4) is provided facing the evaporation source. The evaporation source is heated by an electron beam emitted from the evaporation source, and the evaporated metal from the evaporation source passes through the electron beam, thereby ionizing the evaporated metal.
A method for manufacturing a magnetic recording medium, which comprises accelerating toward the surface of the substrate (3) by an electric field formed in the vicinity of the substrate (3), and causing the magnetic recording medium to adhere to the surface of the substrate. [2] Magnetic recording according to claim 1, in which a negative potential is applied to the base material (3) itself with respect to the evaporation source to accelerate the ionized evaporated metal toward the surface of the base material. Method of manufacturing media. [3] A patent in which an electrode (6) to which a negative potential is applied relative to the evaporation source is provided near the surface of the base material (3) to accelerate ionized evaporated metal toward the surface of the base material. A method for manufacturing a magnetic recording medium according to claim 1. [4] Vacuum container (1) is 10^-^4 to 10^-^5T
A method for manufacturing a magnetic recording medium according to any one of claims 1 to 3, wherein the degree of vacuum is maintained at a degree of vacuum of orr.