JPH01122022A - High-density floppy disk - Google Patents

Abstract

PURPOSE:To lower a coefft. of thermal and moisture expansion and to obtain a high-density recording floppy disk by coating magnetic layers via thin nonmagnetic metallic films on a substrate. CONSTITUTION:The surfaces of a substrate film consisting of polyester, etc., are activated by a glow discharge, etc., and thereafter, the thin nonmagnetic metallic film are formed on both faces of the film in a vacuum. A separately prepd. magnetic coating compd. is then coated on both faces of the film and the coatings are subjected to stages such as surface treating, curing, blanking and surface polishing, by which the floppy disk is completed. The coefft. of thermal and moisture expansion of the substrate 1 is kept small by the intervention of the thin films 3 consisting of nonmagnetic metal Ti or Cu and having about 0.2mum thickness and, therefore, track deviations are decreased and the track density is improved. The high-density recording floppy disk is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-density recording magnetic disk in which a magnetic layer is formed by applying magnetism to a substrate such as a polyester film.

2. Description of the Related Art In recent years, floppy magnetic disks have been widely used for external storage in personal computers and the like. This floppy disk is made by applying magnetic paint to a base material such as polyester, treating the surface, hardening it, beating it into a disc shape, and polishing the surface.
It is manufactured in a predetermined case.

Problems to be Solved by the Invention Floppy disks are required to have high density and large capacity, but because the temperature and humidity expansion coefficient of the disk itself is determined by the temperature and humidity expansion coefficient of the polyester etc. used as the base material, the floppy disk is extremely large. , so the amount of off-track increases,
The problem was that the track density could not be increased.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic disk of the present invention is characterized in that a non-magnetic metal thin film is provided on a substrate made of polyester or the like before the magnetic paint is applied.

Effect The present invention has the above-described structure, so that the temperature-humidity expansion coefficient of the floppy disk, which largely depends on the base material such as polyester, can be reduced.
By keeping it small, it is possible to obtain a high recording density floppy disk with small track deviation and improved track density.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 2 shows a sectional view of a conventional floppy disk.

A magnetic coating film 2 is provided on a base film 1 such as a polyester film by applying magnetic paint.

FIG. 1 shows a cross section of the floppy disk of the present invention. Since the metal thin film 3 is provided on the base film 1 before applying the magnetic paint, the metal thin film layer 3 exists between the base 1 and the magnetic coating film 2.

As a specific example, the thickness is 33 μm and 6211 m.
After activating the surface of a 76 μm polyester film using laglow discharge, etc., a thin metal film was placed on the film (on both sides) in a vacuum, and then a separately prepared magnetic paint was applied onto this film and calendered. Cured.

The contents of these Examples and their temperature/humidity expansion coefficients are shown in the table below.

Next, as a comparative example, the temperature-humidity expansion coefficient of a floppy disk in which magnetic paint was applied on a conventional substrate was also described below and compared with the example.

It can be seen that the comparative example uses a conventional floppy disk and has a higher coefficient of thermal and humidity expansion than the example.

This is thought to be because the metal thin film provided on the surface acts to suppress the expansion of the base, and the fact that the elastic modulus of the metal is significantly larger than that of the base is effective.

Additionally, hydroxyl groups exist on metal surfaces due to reaction with moisture in the air, and these hydroxyl groups improve the adhesion of magnetic coatings, and the metal thin film can also be expected to reduce the light transmittance of floppy disks.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, according to the present invention, the temperature-humidity expansion coefficient of a floppy disk can be reduced, and a high-density recording floppy disk with improved track density can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional floppy disk. 1... Base film, 2... Magnetic coating film, 3... Metal thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A high-density floppy disk characterized by forming a non-magnetic metal thin film on a base and coating a magnetic layer on top of it.