JPH0370856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film on a polymeric substrate.

The improvement in recording density in the field of magnetic recording has been remarkable, and some so-called metal thin film magnetic recording media, which are known as media with theoretically less loss than before, have been put into practical use for audio, and are also being put into practical use for video. It is said to be close.

What is important in obtaining a medium suitable for short wavelength recording is how to obtain a magnetic layer with a high coercive force and a good squareness ratio at high speed.

As far as is known so far, a practical method is to perform oblique vapor deposition in an oxygen atmosphere on a polymer molded substrate that moves along a rotating support.

As a result of research to further improve productivity based on such a method, the present invention has found that, after vapor deposition, if the magnetic layer is pressed almost isotropically with a roller on the same rotating support, performance can be improved. This was based on the discovery that a good magnetic layer could be obtained.

Although it is not always necessary to press on the same rotating support, there is a risk that cracks may occur if the pressure after vapor deposition is performed using separate rollers, and the speed of movement of the rotating support and the moving substrate may be affected. It can be said that pressing on the same rotating support is preferable in order to prevent problems such as scratches on the substrate surface on the side that contacts the rotating support, which sometimes occurs when the substrates are not the same.

FIG. 1 is a block diagram of the main parts of a winding vapor deposition apparatus used to carry out the present invention.

Along the rotary support 1 , the polymer molded substrate 2 is configured to move from a delivery shaft 3 to a winding shaft 4 . As the evaporation source 5, an electron beam evaporation source is used and schematically shown.

Steam flow 7 regulated by incident angle regulation mask 6
A ferromagnetic layer is thus formed.

8 is a point nip roller of the present invention.
The material is preferably silicone rubber or fluorocarbon rubber, and the surface roughness should be about 0.2S. θ is the angle that a line connecting the position of the nip roller 8 and the axis of the rotating support 1 makes with the vertically downward direction.

The pressing force is adjusted by the rubber hardness, spring pressure, etc., but as shown in FIG. 2, the effect of improving the characteristics of the ferromagnetic layer differs depending on the pressure.

More specific examples will be described below.

The experiment was conducted using two types of cylindrical rotating cans with diameters of 50 cm and 100 cm. Furthermore, regarding θ representing the position of the nip roller 8 in FIG. 1, θ ₁ =
It was investigated whether there was a difference between the three cases of 45°, θ ₂ =80°, and θ ₃ =180°. As a result, it was confirmed that the pressure is sufficient as long as it is at least a certain value, regardless of the can diameter or the position of the nip roller.

Figure 2 is in an oxygen atmosphere of 3×10 ^-5 Torr.
Thickness with 85% Co and 15% Ni evaporated at a minimum angle of incidence of 44°
The characteristics of a magnetic layer of 0.13 μm (substrate is polyethylene terephthalate film, thickness 11 μm) are shown.

In this case, if it is 300 g/cm ² or more, the squareness ratio will be 1, and the coercive force will be 18% compared to the case not according to the present invention.
We were able to achieve a much larger value.

This rate of change depends on the magnetic material and the minimum incident angle, but it can ensure an increase in coercive force of approximately 20%. Although the mechanism is not clear, since it is immediately after the thin film is formed, the alignment of the crystals This seems to be because the number of defects is significantly increased. To indirectly confirm this, after vapor deposition, the material was taken out into the atmosphere and the same pressure was applied, but the magnetic properties did not change at all.

On the other hand, although it is experimentally possible to achieve conditions such that the deposition takes place within 1 second using the apparatus shown in FIG. 1, it is not practical. (A vapor deposited film is formed on the nip roller, which may eventually peel off.) I haven't confirmed it, but
The expected effect in that case would be that the curve in FIG. 2 would simply shift to the side of lower pressure.

The effect shown in FIG. 2 was the same even when θ was between 45° and 180°. In practical terms, it is sufficient to set θ to about 120°.

As explained above, according to the present invention, characteristics can be improved when manufacturing at the same speed, and when obtaining the same characteristics, the minimum incident angle can be reduced to increase the vapor deposition efficiency.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the main part configuration of a winding vapor deposition apparatus used to carry out the present invention, and FIG. 2 is a diagram showing the relationship between the nip roller pressing force and the obtained magnetic properties. DESCRIPTION OF SYMBOLS 1... Rotating support body, 2... Substrate, 5... Evaporation source, 8... Nip roller.

Claims (1)

[Claims] 1. A magnetic layer is formed by vapor deposition on a polymer molded substrate that moves along a rotating support, and immediately after vapor deposition, the magnetic layer is applied with a roller along the rotating support at a pressure of 300 g/cm ² or more. 1. A method for manufacturing a magnetic recording medium, characterized in that a pressure treatment is carried out.