JPS63106926A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a weather resistant characteristic and preserving stability by preserving a rolled and vapor deposited article formed by providing a thin magnetic metal or alloy film by a roll-up vapor deposition method on a flexible substrate in a pressurized atmosphere of >=2atm and <=20atm contg. oxidative gas. CONSTITUTION:The rolled and vapor deposited article formed by providing the thin magnetic metal or alloy film by the roll-up vapor deposition method on the flexible substrate is preserved in the pressurized atmosphere of >=2atm and <=20atm contg. oxidative gas. The pressure at the time of pressurization is further preferably >=5atm and <=20atm. The flexible substrate is plastic consisting mainly of plastics such as PE terephthalate, polyimide, polyamide, PVC, cellulose triacetate, polycarbonate, and PE naphthalate. The recording medium having the excellent weather resistance characteristic and preserving stability is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly to a method for manufacturing a metal thin film type magnetic recording medium having excellent weather resistance and storage stability.

[Conventional technology]

As magnetic recording media, so-called "coating type" magnetic recording media, in which a powdered magnetic material is coated and dried together with an organic binder or the like on a non-magnetic substrate, have been widely used. However, in the current trend toward higher densities with shorter wavelengths and narrower tracks, there is active development of "metal thin film type" magnetic recording media that have a large amount of magnetic flux and are suitable for high-density recording. It is being done. These include, for example, a so-called vapor deposition tape using an oblique vapor deposition method of a Co-based material, or a perpendicular magnetization type tape or disk using a CoCr alloy material.

However, such metal thin films, especially magnetic alloys and metals with magnetic properties suitable as magnetic recording materials, have poor weather resistance, and this is one of the biggest obstacles to practical application. In other words, weather resistance is a phenomenon in which, for example, when left in a high temperature and high humidity environment for a certain period of time, the total amount of magnetic flux decreases by 10% or more. This is a serious problem considering the original purpose of the recording medium, which is to preserve records. Furthermore, due to repeated dew condensation and drying processes, visible rust appears on the surface of the media.
As a result, the recording head becomes clogged. Although a number of methods have been proposed to improve the weather resistance of these metal thin film magnetic recording media, most of them are either insufficiently effective or sacrifice other properties in order to obtain weather resistance. . Others require large-scale equipment and have poor productivity. Therefore, there has been a desire for a simpler and more effective improvement in weather resistance.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its object is to provide a method for manufacturing a metal thin film magnetic recording medium with improved weather resistance and storage stability.

[Structure of the invention]

The present invention produces magnetic metal on a flexible substrate by a winding vapor deposition method.
The present invention relates to a method for producing a magnetic recording medium, which comprises storing a rolled vapor-deposited product provided with an alloy thin film in a pressurized atmosphere containing an oxidizing gas of 2 atm or more and 20 atm or less.

The flexible substrate of the present invention is mainly made of polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride,
The substrate is made of plastic such as cellulose triacetate, polycarbonate, or polyethylene naphthalate.

A roll-deposited product is one obtained by a roll-deposition apparatus as shown in FIG. 1 in Example E. FIG. 1 shows a winding vapor deposition apparatus having a λ chamber configuration, in which a flexible substrate 7 is a delivery roll 6.
It is fed out, moves along the cooling drum 2, and is wound up on a winding roll 13. The lower chamber 3 is a vapor deposition chamber, and the vapor flow from the crucible 12 is deposited on the substrate to form a thin film.

FIG. 1 shows a means for forming a magnetic film by oblique deposition, in which a part of the incident vapor flow is regulated by a mask. It is also possible to use means such as controlling the magnetic properties by introducing an oxidizing gas or the like through the gas inlet t1)0.

Figure 1 shows several gas inlet ports t lined up in the vertical direction, but it is possible to create a magnetic film with a desired thickness distribution by appropriately changing the amount of gas introduced from these gas inlet ports. is possible. A rolled vapor-deposited product is obtained in which a magnetic film is vapor-deposited on the winding roll 13 corresponding to the length of the substrate initially set on the delivery roll.

The thus obtained rolled vapor-deposited product is stored in a pressurized atmosphere containing an oxidizing gas for a certain period of time or longer. It is also optional to introduce a rewinding process before storage. The oxidizing gas here is generally oxygen, but it may also be ozone gas or a mixed gas of oxygen and ozone. The pressure during pressurization is 2 atm or more and 20 atm or less, more preferably! It is desirable that the pressure is not less than atmospheric pressure and not more than λθ atmospheric pressure. Below 2 atm, it is difficult to obtain the effects of the present invention, and at fF-20 atm or above, the apparatus becomes large-scale, but not much effect can be expected.

The above-mentioned fixed time varies depending on the film width and winding tension, but is preferably 12 hours or more. It is also possible to apply heat at the same time as pressurization, and similar effects can be seen. However, especially when using a substrate with poor heat resistance such as a polyester substrate, the upper limit of the temperature of the heating treatment is limited.

〔Example〕

Using the vapor deposition apparatus shown in Figure 1,! Co was deposited on a polyethylene terephthalate substrate with a thickness of μm using an oblique evaporation method.
9. Form a deposited magnetic thin film of 5oNi2o atoms. The substrate used was a film @100♂ with a total length of l. Conveyance speed 2.1m1 minute, incident angle θmin”2
j°, film H2oooλ, and 02 gas is introduced from the gas inlet r, 10 at a vacuum degree of j, 0x10 T in the deposition chamber.
Vapor deposition was carried out while introducing an equal amount so that the amount of Here, for the l gas inlet, the one at the top, that is, the most
Only the inlet close to the max section was used. Two rolled vapor-deposited products were created under these conditions. One was left in the atmosphere at room temperature and humidity for 3 days (1) and this was designated as Sample A). The other seven tubes were placed under a pressurized atmosphere of 10 atm.
Save it for 1 day and fc (this is Sample O).

The oxygen atmosphere gas was air compressed by a compressor, and the pressurized container was a partially modified high-pressure test device manufactured by Hirata Seisakusho ■.

From the above-mentioned co-samples thus obtained, μ samples with a size of 10% x 7j% were cut out at intervals of j00 m (referred to as A/~Kahiro and Otsu/~Otsuhiru). The smaller number corresponds to the middle of the roll. More than r samples, t
o Leave in a 0c 04RH atmosphere for one week, and the rate of change in the total magnetic flux φp (Mx/yen) before and after that - Δφm/φm
was measured.

The results are shown in the table below. C value is 4) It can be judged that the smaller the value of this rate of change -Δφm/φm, the better the weather resistance properties are. Sample B shows almost the same low values over all Z/~B≠, and is clearly better than Sample A.

〔Effect of the invention〕

As described above, by using the method of the present invention, a nine-metal thin film magnetic recording medium with excellent weather resistance and storage stability can be easily and uniformly produced.

[Brief explanation of the drawing]

FIG. 7 shows a winding vapor deposition apparatus. l...Vacuum chamber B......feeding roller Ta... Cooling drum r, 10...Gas inlet 13...Take-up roller 12... Evaporation source

Claims (2)

[Claims] (1) Roll-deposited products, in which a thin film of magnetic metal or alloy is provided on a flexible substrate by the roll-deposition method, must be stored in a pressurized atmosphere containing oxidizing gas at a pressure of 2 atm or more and 20 atm or less. A method for manufacturing a magnetic recording medium. (2) The method for manufacturing a magnetic recording medium according to claim (1), wherein the oxidizing gas is oxygen gas.