JPS61240436A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled magnetic recording medium having stabilized magnetic characteristics and form by treating a substrate with glow discharge immediately before the substrate begins to contact a cylindrical can when a metallic thin film magnetic layer is formed by vacuum deposition. CONSTITUTION:A substrate 1 of a high molecular material is treated with glow discharge by a glow discharge electrode 6 immediately before the substrate begins to contact a can 2. The glow discharge electrode 6 is arranged so that the glow discharge is exerted on the part of the substrate 1 which begins to contact the cylindrical can 2. The surface conditions of the substrate 1 are made uniform by the passage of the substrate 1 through a gas under the influence of the glow discharge and the electrification of the substrate 1 is removed. Consequently, the sticking of the substrate 1 on the can 2 is made uniform, a magnetic recording medium without any creases and having uniform characteristics can be obtained. Ar or N2 is preferably used as a gas to be introduced into a vacuum vessel in consideration of its stability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a magnetic recording medium in which a metal thin film magnetic layer is formed on a substrate made of a polymeric material either directly or via an underlayer.

Conventional technology Conventionally, coated magnetic recording media have been used, in which magnetic powder is coated on a non-magnetic substrate, but in order to achieve higher recording density, metal thin films are coated on the non-magnetic substrate. Thin film types formed by vacuum evaporation are being put into practical use.

Metal* is produced using a vacuum evaporation method on a substrate made of polymeric material.
The best method for forming the m-magnetic layer is to steam the substrate while running it along the circumferential surface of a cylindrical can. FIG. 3 schematically shows the internal structure of a vacuum evaporation apparatus using such a method. Substrate 1 made of polymer material
travels along the circumferential surface of the cylindrical can 2 in the direction of the arrow. A magnetic layer is formed on this substrate 1 by an evaporation source 5 .

3.4 are the supply roll and take-up roll of the substrate 1, respectively. Problems to be Solved by the Invention When a magnetic layer is formed on a substrate made of a polymeric material using a vacuum evaporation apparatus as shown in FIG. The characteristics vary in the width direction and length direction of the substrate 1, making it difficult to obtain a stable film. To explain this with an example, a Co-Cr perpendicular magnetic anisotropy film, which is well known as a perpendicular magnetic recording medium, is fabricated using the vacuum evaporation apparatus shown in Fig. 3. When we measured the longitudinal distribution of coercive force, we found a significant change as shown in Figure 4. Also in the width direction, the coercive force in the vertical direction changed as shown in FIG. The cause of this is the temperature of the substrate 1 caused by the non-uniformity of the surface condition of the substrate and the uneven adhesion of the substrate 1 to the can 2, resulting in the formation of parts of the substrate 1 that are in close contact with the can 2 and parts that are not. There may be some unevenness.

In addition to the fact that the magnetic properties are not uniform, especially when the temperature of the can is raised to 150°C or higher, it is very easy to wrinkle (and it is difficult to create a medium with stable magnetic properties and shape). Have difficulty.

An object of the present invention is to provide a method for manufacturing a metal thin film magnetic recording medium having stable magnetic properties and shape.

Means for Solving the Problems The method of manufacturing a magnetic recording medium of the present invention involves running a polymer material substrate along the same surface of a cylindrical can, and depositing a metal thin film magnetic material on the substrate directly or through an underlayer. The present invention is characterized in that when the layer is formed by vacuum evaporation, the substrate is subjected to a glow discharge treatment immediately before the substrate comes into contact with the cylindrical can.

According to this configuration, the glow discharge treatment is applied to the substrate just before the substrate starts contacting the can (immediately here includes the part where the substrate starts contacting the can), so that the surface condition of the substrate becomes uniform. In addition, due to the neutralizing effect of the glow discharge, the charge on the substrate is removed and the substrate uniformly adheres to the can, resulting in a wrinkle-free magnetic recording medium with uniform characteristics.

EXAMPLE Hereinafter, the manufacturing method of the present invention will be explained based on a specific example.

FIG. 1 shows a vacuum evaporation apparatus for carrying out the manufacturing method of the present invention. Components having the same functions as those in FIG. The only difference from FIG. 3 is that a glow discharge treatment is performed by a glow discharge electrode 6. By supplying power to the glow discharge electrode 6 and adjusting the degree of vacuum, glow discharge is generated near the electrode. Note that the glow discharge electrode 6 is arranged so that the glow discharge also extends to the portion where the substrate 1 begins to come into contact with the cylindrical can 2. By passing the substrate 1 through the gas in this glow discharge state, the surface condition of the substrate 1 becomes uniform and the charge on the substrate 1 is removed.

As a result, the adhesion of the substrate 1 to the can 2 becomes uniform, and a wrinkle-free magnetic recording medium with uniform characteristics is obtained.

There are various types of glow discharge, including direct current, alternating current, high frequency, and magnetron type, and any of these types may be used. As the gas introduced into the vacuum chamber to generate glow discharge, A or N2 is preferable from the viewpoint of stability.

In addition, as shown in FIG. 5, the glow discharge electrode is attached to the substrate 1.
If it is installed away from the vicinity of the entrance to the can 2, the above-mentioned effect will be significantly reduced. This is thought to be because the substrate 1 that has undergone the glow discharge treatment comes into contact with the gas in the vacuum chamber and the free roller 7 before it starts contacting the can 2, so that the effect of the glow discharge treatment is weakened.

Further, even if the glow discharge treatment is applied only to one side of the substrate 1, a considerable effect can be recognized, but as shown in FIG. 1 (it is preferable to apply it to both sides of the substrate 1).
The interior of the vacuum chamber 9 is divided into a glow discharge processing section B and a vapor deposited film forming section C by a partition plate 8, and the vacuum degree of the vapor deposited film forming section C is maintained at a higher degree of vacuum than that of the glow discharge processing section B. The magnetic properties of the layer are improved. In Figure 2, 10
is the exhaust pump.

Further, by applying a voltage between the magnetic layer and the circumferential surface of the can 2, the adhesion of the substrate 1 to the can 2 is improved, and a more stable medium can be obtained.

Note that the effects of the present invention are more significant when the peripheral surface temperature of the can 2 is 150° C. or higher. Co-Cr! 1! When producing a perpendicular magnetic anisotropic film using a vacuum evaporation method, the peripheral surface temperature of the can 2 needs to be 150"C or higher, more preferably 200"C or higher. This is particularly effective when producing an anisotropic film.

Next, more specific experimental examples of the present invention will be explained.

[Experiment example] In the vacuum evaporation apparatus shown in Fig. 2, a polyimide film with a thickness of 10 μm was used as the substrate 1, and a Co-Cr perpendicular magnetic anisotropic film with a thickness of 300 OA was formed thereon as a magnetic layer. . Here, the temperature of the circumferential surface of can 2 was set to 230°C. A high frequency power source of 13.6 MHz was used as the glow discharge power source, and the glow discharge electrode 6 was installed just before the polyimide film began to come into contact with the cylindrical can. In order to generate glow discharge, A' is introduced from near the glow discharge electrode, and the degree of vacuum near the glow discharge part is set to 0.01 Torr.
And so.

In this state, the degree of vacuum near the deposited film formation area is 1.2×1O
-4T Orr. In addition, the peripheral surface of can 2 and co
-Cr! ! A voltage of 120 volts was applied between the film and the direct magnetic anisotropic film.

The film thus formed had no wrinkles, had uniform properties in the length direction and width direction, and had excellent properties as a perpendicular magnetic recording medium. On the other hand, when the glow discharge treatment was not performed, a film with uniform characteristics in the length and width directions could not be obtained. Furthermore, as mentioned above, a similar effect is observed when a co-Cr film is formed via an underlying layer such as an oxide film instead of directly forming a co-Cr film on a polyimide film. Ta.

As described in the detailed description of the invention, in the method for manufacturing a magnetic recording medium of the present invention, immediately before the polymeric material substrate starts to come into contact with the cylindrical can, the substrate is subjected to a glow discharge treatment, and the substrate is treated with glow discharge along the circumferential surface of the cylindrical can. In order to vacuum-deposit a thin magnetic layer of gold onto a moving polymer substrate directly or through an underlayer, it is deposited immediately before the substrate starts contacting the can (immediately here includes the part where the substrate starts contacting the can). ) When the substrate is treated with glow discharge, the surface condition of the substrate becomes uniform, and the static electricity removal effect of the glow discharge removes the charge on the substrate, allowing it to adhere uniformly to the can, resulting in a completed magnetic recording medium. The magnetic layer had no wrinkles on the polymer material substrate and had uniform characteristics in the length and width directions.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a vacuum evaporation apparatus for carrying out the manufacturing method of the present invention, FIG. 2 is a configuration diagram of another embodiment of FIG. 1, and FIG. 3 is a configuration diagram of a conventional vacuum evaporation apparatus. Figure 4 is an explanatory diagram showing the unevenness of coercive force when a magnetic layer is deposited by the conventional method, and Figure 5 shows the arrangement of the glow discharge electrode in Figure 1.
It is an explanatory diagram of the installation position. 1... Polymer material substrate, 2... Cylindrical can, 3.
... Supply roll, 4... Winding roll, 5... Evaporation source, 6... Glow discharge electrode, 8... Partition plate, 9
...Vacuum chamber, B...Glow discharge processing section, C...Vapour-deposited film forming section agent Yoshihiro Morimoto Figure 7 Ya. 5-5 Exercises Figure 3 Figure 4 Iha]

Claims (1)

[Claims] 1. When a polymer material substrate is run along the circumferential surface of a cylindrical can and a metal thin film magnetic layer is formed on the substrate directly or via a base layer by vacuum evaporation, A method for manufacturing a magnetic recording medium, wherein the substrate is subjected to glow discharge treatment immediately before the substrate starts contacting the cylindrical can. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein glow discharge treatment is performed on both sides of the substrate. 3. A method for manufacturing a magnetic recording medium according to claim 1, characterized in that the glow discharge treatment and the deposition of the magnetic layer are performed in separate chambers having a pressure difference between the two chambers in a vacuum chamber. . 4. The method of manufacturing a magnetic recording medium according to claim 1, characterized in that the potentials of the magnetic layer and the circumferential surface of the cylindrical can are made different. 5. The method for manufacturing a magnetic recording medium according to claim 1, characterized in that Ar or N_2 is used as the gas for glow discharge. 6. The method of manufacturing a magnetic recording medium according to claim 1, characterized in that a Co--Cr perpendicular magnetic anisotropic film is used as the magnetic layer.