JPH0362308A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent generation of wrinkles in the process of film forming and to obtain a high-guality Co-Cr perpendicular magnetic recording medium having a polymer film as a substrate by specifying the tensile elasticity of the polymer film at specified temp. CONSTITUTION:In the Co-Cr perpendicular magnetic recording medium having the polymer film substrate, the polymer film is specified to have the tensile elasticity of >=150kg/mm2 at 150 - 300 deg.C. Temp. of the polymer film during the process of film forming elevate temporarily to 150 - 300 deg.C because of heating of the substrate or of an impact by high-energy particles. The elasticity of the film decrease with elevation of temp. and at 300 deg.C the elasticity becomes less than half of that at room temp. By using such a film that has >=150 kg/mm2 elasticity at high temp, and more preferably, >=350 kg/mm2, generation of wrinkles in the film during vapor deposition can be prevented. Moreover, by using a polymer film having the surface roughness Ra of <=100 A and the maximum roughness height Rmax of 200 Angstrom from the viewpoint of spacing property for recording, the obtd. medium has higher qualities.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media. More particularly, the present invention relates to magnetic recording media with improved substrate films.

[Prior Art] In recent years, with the increase in the density of magnetic recording, research on perpendicular magnetic recording systems has been actively conducted. One of the media suitable for such a perpendicular magnetic recording system is a Co--Cr1 direct magnetic recording medium manufactured by a method such as a vacuum evaporation method or a sputtering method.

In order to use this Co-Cr-1 direct magnetic recording medium to produce media with polymer film as a substrate, such as magnetic tapes and floppy disks, it is necessary to form a film while winding a long, thin film with a roller. be. However, the technology for winding such thin films is extremely difficult, and wrinkles may 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 area, wear and sticking between the film and roller will be large.
Wrinkles are likely to occur.

Further, in order to produce a Co--Cr perpendicular magnetization film having good vertical magnetic properties, it is necessary to heat the substrate or increase the energy of the deposited particles. In either case, the substrate film becomes temporarily hot 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.

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the disadvantage of the generation of wrinkles in the deposited film, which the prior art described above, and thereby provide a magnetic recording medium with excellent reliability. .

[Means for Solving the Problems] 1) In order to achieve the 11th object, the present invention provides a Co--Cr perpendicular magnetic recording medium having a polymer film as a substrate, in which the polymer film is heated at 150°C to 300°C. Provided is a magnetic recording medium having a tensile modulus of elasticity of 150 kg/mm2 or more at °C.

The tensile modulus of the polymer film at 150 to 300°C is preferably 350 kg/a+n+2 or more.

In addition, the center line average roughness Ra of the polymer/film is 100
It is preferable that the maximum height Rn+ax of the surface roughness is 200 Å or less at the input f.

[The film temperature during the production of the working film is 150°C or more due to substrate heating or impact from high-energy particles.
The temperature reaches 300℃. The elastic modulus of a polymer film decreases as the temperature rises, and at 300° C. it becomes less than half of that at room temperature. The inventor has determined that the elastic modulus at such high temperatures is 15
0kg/I! 1I112 or more, more preferably 350
It has been found that when a substrate film of kg/mm2 or more is used, wrinkles generated in the film during vapor deposition can be eliminated. This is thought to be because when the elastic modulus is low, the film is less likely to deform, and furthermore, the contact area with the roller is reduced, resulting in less wear.

Also, considering the spacing dependence of perpendicular magnetic recording,
Surface roughness Ra is 100 Å or less, maximum height Rmax is 2
High quality magnetic recording media can be obtained using 00 Å polymer films.

[Example] Hereinafter, the present invention will be explained in detail using Example f1.

Co-C using a vacuum evaporation apparatus 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, Co and Cr in the evaporation source 6 located below the heating roll are heated and melted by the electron beam from the electron gun 5, forming a C0-Cr perpendicular magnetization film.

As the substrate film 4, a polyimide film with a thickness of 20 μm and having a tensile modulus shown in FIG. 2 was used. Co-
The thickness of the Cr film is 2000 Å, and the composition is Co:
Cr=80:20. Vapor deposition speed is 1ooo/Sec% Film feeding speed is 2m/mains
The temperature of the heating roll was 250°C.

Using a sputtering device like the one shown in Figure 3, Co-
A Cry direct 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 directly magnetized Co--Cr film is formed from the target 15 in the heating roll section by high-frequency magnetron sputtering. During the sputtering process, Ar gas was introduced into the reaction chamber from the gas inlet 16.

A polyimide film with a thickness of 10 μm and having a tensile modulus shown in FIG. 4 was used as the substrate film. Co-C
The thickness of the r film is 2000 Å, and the composition is Co:C by weight.
r=80:20. Film formation rate is 50'/
The feeding speed of the 5ec1 film was 15C/ll1n, and the temperature of the heating roll was 150°C.

A Co--CrI: directly magnetized film was prepared in the same manner as in Example 1, except that a polyimide film having a thickness of 20 μm and having an elastic modulus shown in FIG. 5 was used as the flexible upper plate film.

Film thickness 1 having the elastic modulus shown in Figure 6 as αL and substrate film
A Co-CrI direct decomposition film was prepared in the same manner as in Example 2 except that a 0 μm polyimide film was used.

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.

As is clear from the above results, 150°C to 300°C
When a polymer film having a tensile modulus of elasticity of 150 kg/ram2 or more is used as a substrate, wrinkles do not occur in the substrate film during film formation, and a magnetic recording medium of excellent quality can be 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.
Other films such as polyester films and polyethylene terephthalate films can also be suitably used as long as they have a tensile modulus of g/mm2 or higher.

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 mounted magnetic recording media is also co
The material is not limited to -Cr, but Fe, Ni, or alloys thereof can also be used.

Furthermore, if the polymer film substrate of the present invention is used in the production of not only perpendicular magnetic recording media but also thin-film magnetic recording media with in-plane magnetized films, it is possible to obtain high-quality magnetic recording media that do not generate wrinkles. .

[Effects of the Invention] As explained below, by using a polymer film with a tensile modulus of 150 kg/mm2 or more at 150°C to 300°C as a substrate, a high quality film with no wrinkles during film formation can be achieved. magnetic recording media 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 a polyimide film used for producing the magnetic recording medium of Example 1 of the present invention. FIG. 3 is a schematic diagram showing an example of a sputtering apparatus used for producing the magnetic recording medium of the present invention, and FIG. 4 is a characteristic diagram showing the relationship between temperature and tensile modulus of 5 is a characteristic diagram showing the relationship between temperature and tensile modulus of the polyimide film used in the production of the magnetic recording medium of Example 2, and FIG. FIG. 6 is a characteristic diagram showing the relationship between temperature and tensile modulus of the polyimide film used in the production of the magnetic recording medium in Comparative Example 2. . l, 11... Supply roll 2.12... Heating roll 3.13... Take-up roll 4.14... Polymer film substrate 5... Electron gun 6... Evaporation source 15...・Target 16...Gas inlet

Claims (4)

[Claims] (1) In a Co-Cr perpendicular magnetic recording medium using a polymer film as a substrate, the temperature of the polymer film is 150°C to 3°C.
A magnetic recording medium having a tensile modulus of elasticity of 150 kg/mm^2 or more at 00°C. (2) The magnetic recording medium according to claim 1, wherein the polymer film has a tensile modulus of elasticity of 350 kg/mm^2 or more at 150°C to 300°C. (3) The center line average roughness Ra of the polymer film is 10
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a thickness of 0 Å or more. (4) Maximum height R_m of surface roughness of the polymer film
3. The magnetic recording medium according to claim 1, wherein _a_x is 200 Å or less.