JPH0366022A - Thin film-type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the high-quality recording medium which is not creased when the film is formed by using a film having a specified static friction coefficient when a stainless steel column under specified conditions is placed on the film and slid at a specified temp. as a substrate. CONSTITUTION:A polymeric film is placed on a heated stainless steel sheet, and a stainless steel column having 0.1mum surface roughness on the center line, 0.4mum maximum surface roughness, 12mm diameter and 20kg weight is placed thereon. When the film is heated to 150-300 deg.C and the column is slid on the film, the static friction coefficient is controlled to <= 0.6, and such a film is used as the substrate. The substrate 4 is inserted between reels 1 and 3 through a roll 2, and the Co and Cr as the vaporization source 6 are vaporized by an electron beam to vacuum-deposit a perpendicular magnetic film on the substrate 4. Consequently, a high-quality recording medium which is not creased when the film is formed is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic recording medium. More specifically,
The present invention relates to thin film magnetic recording media having improved substrate films.

[Prior Art] Magnetic recording media that have been widely used in the past are coating-type media in which a magnetic layer is formed by coating a magnetic coating mainly consisting of acicular magnetic powder and a polymeric binder on a non-magnetic substrate. This is a magnetic recording medium.

Currently, there is a trend toward higher density magnetic recording and reproducing devices, and there is a demand for magnetic recording media with excellent short wavelength recording characteristics.

However, there are limits to the improvement of short wavelength recording characteristics in coated magnetic recording media. On the other hand, C such as CoCr
A metal thin film type magnetic self-recording medium in which a ferromagnetic material mainly composed of O is deposited on a non-magnetic substrate by a so-called physical vapor deposition method such as vacuum evaporation, sputtering, or ion blating, has Since no non-magnetic binder is mixed in, it is possible to achieve extremely high residual magnetic flux density, and because the magnetic outer layer can be formed extremely thin, it is said to have high output and excellent short wavelength response. has advantages. Due to this feature, thin film magnetic recording media have recently become the -E type of magnetic media.

[Problems to be Solved by the Invention] In recent years, with the increase in the density of magnetic recording, research on thin-film perpendicular magnetic recording systems has been actively conducted. In order to use this thin-film type perpendicular magnetic recording medium to produce a medium using a polymer film as a substrate, such as a magnetic tape or a floppy disk, it is necessary to form a film while winding a long thin film with a roller.

However, the technology for winding such thin films is extremely difficult, and wrinkles will occur if the tension becomes even slightly uneven.

In particular, perpendicular magnetic recording has a large effect on spacing.
Since it is necessary to use a film with extremely good surface properties, wear and sticking between the film and roller will be large.
Wrinkles are likely to occur.

Furthermore, in order to produce a Co--Cr perpendicularly magnetized film having good perpendicular magnetic properties, it is necessary to heat the substrate or increase the energy of the deposited particles. In any case, the substrate film becomes hot at times during film production. As described above, when the film is heated to a high temperature, wrinkles are more likely to occur and a flat medium cannot be obtained.

It is an object of the present invention to eliminate the drawback of the above-mentioned prior art, which is the occurrence of wrinkles in the deposited film, and thereby provide a thin film magnetic recording medium with excellent reliability.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides a thin film magnetic recording medium having a polymer film as a substrate, in which a stainless steel (SUS) deck on which the polymer film is heated is used. E, and the center line surface roughness Ra is 0.
When a SUS cylinder with a diameter of 121h and a weight of 20g is placed and the film slides on the bottom of the cylinder, the coefficient of static friction is the film temperature of 150. Provided is a thin film type magnetic recording medium characterized in that it has a hardness of 0.6 or more at a temperature of 0.degree. C. to 300.degree.

The thin film magnetic recording medium is, for example, a Co-Cr perpendicular magnetic recording medium.

It is preferable that the center line average roughness Ra of the polymer film is 100 Å or less, and the maximum height Rmax of surface roughness is 200 Å or less.

[Operation] In the production of thin-film magnetic recording media, the occurrence of wrinkles becomes a particular problem when the temperature during film formation is relatively high. For example, the film temperature during the production of a co-Cr perpendicularly magnetized film instantaneously reaches a high temperature of 150° C. to 300° C. due to substrate heating or impact from high-energy particles.

The inventor of the present invention has developed the film-3US under such high temperature conditions.
It has been found that when a substrate film with a static friction coefficient of 0.6 or less is used, wrinkles that occur in the film during vapor deposition can be eliminated.

This is thought to be because when the film is heated and expanded, if the friction is large, the film and roller do not slip, and the expanded film lifts up and becomes wrinkled. In addition, considering the spacing dependence of perpendicular magnetic recording, the surface roughness Ra is 100 Å or less, and the maximum height RIla
If a polymer film with a thickness of 200 Å is used, a high quality thin film magnetic recording medium can be obtained.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Co-C using a vacuum evaporator as shown in Figure 1
An r-perpendicular magnetic recording medium was manufactured. The film substrate 4 sent out from the supply roll 1 is wound onto a take-up roll 3 via a heating roll 2. At this time, Go and Cr in the evaporation source 6 located at the bottom of the heating roll are heated and melted by the electron beam from the electron gun 5, and a Co--Cr1: directly magnetized film is formed.

As the substrate film 4, a polyimide film having a thickness of 20 μm and having a coefficient of static friction shown in FIG. 2 was used. Co-
The thickness of the Cr film is 2000 Å, and the composition is Co:
Cr=80:20. The deposition rate is 1000^
/sec, the film feed speed was 2 m/mtn, and the temperature of the heating roll was 250°C.

Practical Principle 14 Using a sputtering device as shown in Fig. 3,
A Cr perpendicular magnetic recording medium was manufactured. The film substrate 14 sent out from the supply roll 10 is wound onto a take-up roll 13 via a heating roll 12 . At this time, a Co--Cr perpendicularly magnetized film is formed by high-frequency magnetron sputtering from the target 15 located at the bottom of the heating roll. During the sputtering process, Ar gas was introduced into the reaction chamber from the gas inlet 16.

As the substrate film, a polyimide film having a thickness of 10 μm and having a coefficient of static friction shown in FIG. 4 was used. Co-C
The thickness of the r film is 2000 Å, and the composition is Co:C by weight.
r=80:20. Film formation speed is 50/5
The ecs film feeding speed was 15 mm/win, and the temperature of the first heating roll was 150°C.

Example 1 except that a polyimide film with a thickness of 20 μm and having a coefficient of static friction shown in FIG. 5 was used as the retaining upper substrate film.
A Co--Cr perpendicular magnetization film was produced in the same manner.

Comparison 1 A Co--Cr perpendicular magnetization film was prepared in the same manner as in Example 2, except that a 10 μm thick polyimide film having a coefficient of static friction shown in FIG. 6 was used as the substrate film.

During the production of each Co--Cr perpendicularly magnetized film, wrinkles were observed in the polyimide film with the naked eye.

The observation results are summarized in Table 1 below.

(Left below) Table - As is clear from the above results, when a polymer film with a static friction coefficient of 0.6 or less is used as a substrate, wrinkles do not occur on the substrate film during film formation, and excellent quality magnetic properties can be obtained. A recording medium is obtained.

Although the present invention has been described above with respect to a polyimide film, the polymer film that can be used in the present invention is not limited thereto, and any polymer film having a coefficient of static friction of 0.6 or less at 150°C to 300°C can be used. and other films such as polyphenylene sulfide film,
Polyamide films and the like can also be suitably used.

Further, the film forming method is not limited to vacuum evaporation and sputtering, but any vapor deposition method used for manufacturing thin film magnetic recording media can be used.

The ferromagnetic material used in the production of direct magnetic recording media is also Co
The material is not limited to -Cr, and Fe, Ni, or alloys thereof can also be used.

In addition, not only perpendicular magnetic recording media, but also when the temperature during film formation is 15
Even in the production of thin-film magnetic recording media with obliquely deposited films at temperatures of 0° C. to 300° C., by using the polymer film substrate of the present invention, it is possible to obtain high-quality magnetic recording media free from wrinkles.

[Effects of the Invention] As explained above, by using a polymer film with a static friction coefficient of 0.6 or less at 150°C to 300°C as a substrate, high quality thin film magnetic recording without wrinkles occurring during film formation can be achieved. A medium, particularly a perpendicular magnetic recording medium, can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a vacuum evaporation apparatus used for producing the magnetic recording medium of the present invention, and FIG. 2 is a schematic diagram showing an example of a vacuum evaporation apparatus used for producing the magnetic recording medium of Example 1 of the present invention. FIG. 3 is a characteristic diagram showing the relationship between temperature and static friction coefficient of a polyimide film; FIG. 3 is a schematic diagram showing an example of a sputtering apparatus used for producing the magnetic recording medium of the present invention;
The figure is a characteristic diagram showing the relationship between the temperature and the coefficient of static friction of the polyimide film used in the production of the magnetic recording medium of Example 2 of the present invention, and FIG. FIG. 6 is a characteristic diagram showing the relationship between the temperature and static friction coefficient of the polyimide film obtained in Comparative Example 2.
FIG. 2 is a characteristic diagram showing the relationship between temperature and static friction coefficient of a polyimide film used in the production of a magnetic recording medium in FIG. 1.11... Supply roll 2.12... Heating roll 3.13... Take-up roll 4.14... Polymer film substrate 5... Electron gun 6... Evaporation head 15...・Target 16...Gas introduction [1

Claims (4)

[Claims] (1) In a thin-film magnetic recording medium using a polymer film as a substrate, the polymer film is placed on a heated stainless steel (SUS) flat plate, and the center line surface roughness Ra is 0.1 μm. Maximum surface height Rmax
has a surface roughness of 0.4 μm, a diameter of 12 mm, and a weight of 2
The coefficient of static friction when a 0g SUS cylinder is placed on it and the film and the bottom of the cylinder slide is at a film temperature of 150°C to 30°C.
A thin film magnetic recording medium characterized in that the temperature is 0.6 or less at 0°C. (2) The thin film magnetic recording medium according to claim 1, which is a Co--Cr perpendicular magnetic recording medium. (3) The center line average roughness Ra of the polymer film is 10
3. The thin film magnetic recording medium according to claim 1, wherein the thickness of the thin film magnetic recording medium is 0 Å or less. (4) Maximum height Rma of surface roughness of the polymer film
3. The thin film magnetic recording medium according to claim 1, wherein x is 200 Å or less.