JPS62183080A - Magnetic disk - Google Patents

Abstract

PURPOSE:To eliminate corrosion, and to obtain excellent durability by using a methanol extract whose pH exceeds a specified value, as a liner of a case. CONSTITUTION:As for a magnetic disk, a disk body 10 is contained in a case 20. As for the body 10, a polyethylene terephthalate film is a base body, and on both its faces, a soft magnetic metal thin layer 12, a vertical magnetic recording layer 13, and a protective layer consisting of an inorganic matter are laminated. The case 20 uses a liner 21, and as for the liner 21, pH of its methanol extraction is >=4. This pH is a value obtained by measuring an extract which is eliminated a solvent, by extracting the liner 21 by methanol. A corrosion of the disk body is caused by a strong acid component being a low pH substance contained in the liner, and accordingly, by setting the pH of a methanol extract of the liner to >=4, the corrosion is eliminated, and the magnetic disk whose durability is excellent can be obtained.

Description

[Detailed Description of the Invention] Field of Application] The present invention relates to a magnetic disk in which a flexible disk body is rotatably housed in a case. The present invention relates to a magnetic disk using a disk body.

[Prior Art] The above-mentioned magnetic disk is well known as a floppy disk and a micro disk, and is used as an auxiliary memory for computers.
It is often used as a place.

In recent years, the demand for high-density recording has become increasingly high.
As an alternative to the conventional coating type using a binder,
A magnetic recording layer using a ferromagnetic gold RFfJ film, or a metal such as one using a cobalt-based alloy We having perpendicular magnetic anisotropy as disclosed in Japanese Patent Publication No. 58-91, etc.; A thin-film magnetic recording medium has been proposed.

However, when such a metal thin film is used as the magnetic recording layer, the friction between the magnetic recording head and the F! Due to its high A resistance, it is susceptible to wear and scratches and lacks durability.

For this reason, conventionally, ferromagnetic metal thin films were used as protective layers such as polymers, high hardness metals, etc. Various types of devices equipped with Lamix, etc. have been proposed.

In a magnetic disk using a sliding type magnetic recording medium with these protective layers (I1), its wear resistance, that is, the SFi of the magnetic recording medium when it is repeatedly run on a VTI head, is higher than that of the conventional coated type ( Although inferior to magnetic disks using aerodynamic recording media, 1Q magnetic disks are being developed that are close to the actual level.

[Problem to be Solved by the Invention 1] In order to further improve the current situation, the present inventors have also developed a thin film type magnetic recording medium provided with a protective layer made of an inorganic material. Various tests have been conducted on the durability and reliability of a magnetic disk in which a known perpendicular magnetic recording medium is rotatably housed in a case with a liner similar to a conventional floppy disk. As a result, the above-mentioned thin-film magnetic disk has improved wear resistance and
Endurance! Although the operational life such as A scratch resistance is greatly improved, if it is stored unused for a long period of several months or more, corrosion will occur in the part that is thought to have been in contact with the liner of the magnetic recording medium. It was discovered that the surface of most of the spots was swollen, which was a serious problem with its durability.

The present invention was made in order to solve the problem of corrosion peculiar to magnetic disks in which a thin-film magnetic recording medium is housed in a case with a liner. The purpose is chino.

[Configuration 1 of the invention The above objects are achieved by the invention as follows.

That is, the present invention provides a magnetic disk in which a flexible disk body having a recording layer made of a magnetic metal thin film is rotatably housed in a case, in which the methanol extract of the liner of the case has a methanol extract of 4 or more days. This is a magnetic disk characterized by the following.

The above-mentioned present invention was made as follows.

When we observed the corrosion-prone areas on the disk body, we found stains that appeared to have been transferred from the liner to most of the areas. Therefore, it is thought that the corrosion is caused by this dirt and is caused by strong acid components, which are low pl-1 substances such as oils contained in the liner, and as a result of various investigations, the present invention was conceived.

The present invention will be explained in detail below.

The disk body of the present invention is a thin film type perpendicular magnetic recording medium whose practical use is long-awaited due to its high-density recording characteristics. It is clear that it can be done. That is, a thin film magnetic recording medium in which a magnetic recording layer made of a thin magnetic metal film is formed on a non-magnetic support, and if necessary, a protective layer made of an inorganic material is further formed on the recording layer by a thin film forming method such as physical vapor deposition. are all applicable. For example, a polymer film such as polynisdel may be used as the support, and Go
-P type, Co type, co-Fe type.

Known materials such as Go-JJi, GO-Qr, and Fe-Ni can be used in a single layer or in combination in multiple layers.

The inorganic protective layer that improves the lifespan of motion includes metals such as AM, Si, Co, Cu, and Cr.

Examples include Ni, Rh, Pd, PI, and alloys thereof, and examples of ceramics include carbides, nitrides, M oxides, etc. of various metals and alloys. Among these inorganic substances, those in which the present invention is more effective are metal oxides, specifically oxides of aluminum, cobalt, cobalt-chromium alloys, and the like.

The case of the present invention has a liner on the inner surface, and plastic such as vinyl chloride resin can be used. The wall thickness of the case is not particularly limited, and it may be a flexible case or a hard case that does not easily deform.

The liner of the present invention cleans fine particles such as dust adhering to the surface of the disk body and abrasion particles generated by sliding between the magnetic head and the disk body. It eliminates the harmful effects of recording and reproducing, and any known material can be used regardless of its form or material as long as it has this cleaning effect.

For example, the forms include cloth-like materials such as woven fabrics, raised fabrics, and non-woven fabrics, and the materials include natural fibers such as cotton, recycled fibers such as rayon, semi-synthetic fibers such as acetate, etc.
Polypropylene, polyspur.

71S can be made from synthetic fibers such as nylon. A thickness of 50 to 1000 μm is usually used.

Preferably, the liner is impregnated with a lubricant. Any known lubricant can be used as is.

Such lubricants preferably have a pl-1 of 4 or more, and include, for example, lubricants mainly composed of highly fluorinated alkyl polyethers disclosed in Japanese Patent Publication No. 55-2666, nonionic surfactants, and the like.

What is important in the rffi of the present invention is that the above-mentioned liner has a pl-1 of methanol extract of 4 or more. When the liner is impregnated with a lubricant, it goes without saying that the above-mentioned of-1 should be 4 or more in the impregnated state. This liner can be easily realized by selecting the material and lubricant. Here, the pH of the present invention is a value measured by extracting the liner with methanol, removing the solvent by evaporation, applying the extract to a pH test paper, adding water dropwise as necessary, and measuring the color change. .

To make the magnetic disk of the present invention described above, a magnetic recording layer is formed on a non-magnetic support such as a polynisdel film by a thin film forming method such as electroplating, chemical plating, vacuum evaporation, sputtering, or ion plating. A magnetic disk main body is made by punching to a predetermined size, and the magnetic disk is inserted into a case with a liner having a methanol extract rll-1 of 4 or more pasted on the inner surface.

When providing a protective layer on the magnetic recording layer, it can be provided in the same manner as the magnetic recording layer, or the magnetic recording layer, once formed, can be ion bombarded in an oxidizing atmosphere to form a magnetic metal oxide layer. The outer surface layer can be provided by a method of increasing the degree of oxidation of the outer surface layer than the inside of the recording layer. When using the above magnetic disk of the present invention,
The magnetic recording layer is in partial contact with the liner, the magnetic disk body rotates, while the case remains stationary, and the magnetic recording head contacts the rotating disk to perform recording and reproduction.

The effects of the present invention will be specifically illustrated below with reference to Examples.

[Embodiment] FIG. 1 shows a configuration example of the present invention, which is a magnetic disk in which a disk body 10 made of a flexible double-sided perpendicular magnetic recording medium is housed in a case 20.

The disk body 10 has a diameter of 5.25 inches and a thickness of 50μ.
The substrate 11 is a polyethylene terephthalate film with a thickness of 1.5 mm, and on both sides thereof a thin soft magnetic metal layer 12 with a high magnetic permeability made of a nickel-iron alloy of 0.4 μm and an alloy thin film of cobalt chromium (chromium: 20 wt%) with a thickness of 0.4 μm. A perpendicular magnetic recording layer 13 consisting of the above is sequentially laminated by the facing target sputtering method as in JP-A-57-100627, and then reactive sputtering in an oxidizing gas atmosphere using cobalt metal as a target is applied. A protective layer 14 of 200 cobalt oxide CO3O4 was laminated by the magnetron sputtering method, and a protective layer 14 of 200 alumina AU303 was laminated by the magnetron sputtering method. The protective layer was analyzed using Auger deuteron spectroscopy (8ES) and X-ray diffraction (Dx).
This was done by

A case 20 having a liner 21 was prepared.

One is 1) l-1 of methanol extract consisting of 200 μm thick rayon (80%) and polypropylene (20%).
is a nonwoven fabric (rayon lpO type) with a pH of 5, and the pH of the methanol extract made of rayon is 3, with other properties being the same.
Nonwoven fabric (rayon type), and nonwoven fabric with pH 3 of methanol extract consisting of polyester (polyester type)
It is. Note that the EIH of the liner was measured as described above. Specifically, the liner was extracted with methanol, and the extract after evaporation of the solvent was extracted with I) H test paper (all-purpose 1 manufactured by Toyo Roshi).
-1 test paper 1) l-11, 0 to 1) l-111, Q) was coated, water was dropped, and the color tone change was measured.

The various disk bodies 10 described above were housed in these cases 20 to form magnetic disks, and the following corrosion properties were evaluated.

That is, after each sample of the magnetic disk was allowed to stand in an atmosphere of 60° C. and 90% RH for one week, the surface of the disk body 10 of each sample was observed with a microscope at a magnification of 50 to 100 (3) to determine the corrosion point. The evaluation results are shown in Table 1.

Table 1 From Table 1, in Examples 1 and 2.3 in which the liner was made of a nonwoven fabric with a pl-1 of 5, no corrosion occurred at all, and the present invention produced a thin film type magnetic disk with excellent corrosion resistance. I understand that.

In addition, Example 2. Comparative example 3. Exactly the same results were obtained for the sample of Comparative Example 4 in a long-term corrosion evaluation test in which it was left in a storage rack in a normal city without air conditioning for about one year without being touched. The effectiveness of the test was confirmed.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a magnetic disk according to an embodiment of the present invention. 10: Disk body. 11: Substrate. 12: Soft magnetic metal thin layer. 13: Perpendicular recording layer. 14: Protective layer. 20 Nibra Stick Case. 21: Liner

Claims (1)

[Claims] 1. A magnetic disk in which a flexible disk body having a recording layer made of a magnetic metal thin film is rotatably housed in a case, wherein the pH of the methanol extract in the liner of the case is 4 or more. A magnetic disk characterized by: 2. The magnetic disk according to claim 1, wherein the disk body has a protective layer made of an inorganic substance on the recording layer. 3. Claim 2, wherein the protective layer is a metal oxide.
Magnetic disk described in section. 4. The magnetic disk according to claim 1, 2, or 3, wherein the disk body has recording layers on both sides.