JPS63106927A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a weather resistant characteristic and preserving stability by providing a thin magnetic metal or alloy film by a roll-up vapor deposition method on a flexible substrate, then coating an oxidizing agent or the diluent thereof on the thin film and/or the substrate surface on the side opposite from the thin film and drying the coating. CONSTITUTION:The thin magnetic metal or alloy film is provided by the roll-up vapor deposition method on the flexible substrate and thereafter, the oxidizing agent or the diluent thereof is coated on the thin film or the substrate surface on the side opposite from the thin film and is dried. The flexible substrate is plastic substrates consisting mainly of PE terephthalate, polyimide, polyamide, PVC, cellulose triacetate, polycarbonate, PE naphthalate, etc. Chlorates such as; for example, potassium chlorate and sodium chlorate or perchlorates such as; for example, potassium perchlorate, sodium perchlorate and ammonium perchlorate are usable as the oxidizing agent. The thin metallic film type magnetic recording medium having the improved weatherability is thereby uniformly produced.

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 with excellent weather resistance.

[Conventional technology]

As magnetic recording media, so-called "coating type" magnetic recording media, in which a powdered magnetic material is coated on a non-magnetic substrate together with an organic binder and dried, have been widely used.

However, the recent demand for high-density recording has become extremely steep, and there are some aspects that conventional magnetic recording media cannot meet. 2. Description of the Related Art As a medium having sufficient electromagnetic conversion characteristics even under high-density recording conditions, an r-metal thin film type magnetic recording medium having a large amount of foundation flux is being developed.

However, metal thin film magnetic recording media have problems with weather resistance, which is the biggest barrier to full-scale practical use. Specifically, there is a phenomenon in which the total amount of magnetic flux φm decreases over time. There is also the problem that rust is generated by repeating the process of dew condensation and drying in an atmosphere of corrosive gas such as sulfur dioxide gas. If rust occurs to the extent that it is visible to the naked eye, the recording/reproducing head may become clogged, which poses a major practical problem.

Various methods have been proposed to improve the weather resistance of the metal thin film type magnetic recording media, but most of them are not sufficiently effective in improving weather resistance, or require large-scale equipment. They are facing problems such as low productivity. It has been desired to develop a simpler and more effective method for improving weather resistance.

[Purpose of the invention]

The present invention was developed in view of the above circumstances, and relates to a method for manufacturing a metal thin film type magnetic recording medium having excellent 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 forming an alloy thin film, and then coating and drying an oxidizing agent or a diluted solution thereof on the thin film or the surface of the substrate opposite to the thin film.

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.

The rolled vapor deposition product of the present invention is produced, for example, using the rolled vapor deposition apparatus shown in FIG. What is shown in FIG. 1 is a conventional take-up vapor deposition apparatus for oblique vapor deposition, in which a flexible substrate 7 is sent out from a delivery roll 6, a magnetic metal thin film is deposited in a vapor deposition chamber 3, and then the flexible substrate 7 is wound up. It is wound up into roll/2. Depending on the scale of the apparatus, etc., a predetermined length of the vapor-deposited product is wound onto a take-up roll/J.

In the present invention, an oxidizing agent or a diluted solution thereof is applied and dried on the vapor-deposited film of the rolled vapor-deposited product obtained as described above or on the surface of the substrate opposite to the vapor-deposited film. Here, as the oxidizing agent, chlorates such as potassium chlorate, sodium chlorate, etc., or perchlorates such as potassium perchlorate, sodium perchlorate, ammonium perchlorate, etc. can be used. In the case of, for example, these are dissolved in warm water, then coated and dried at the desired concentration. Also possible are nitrates such as ammonium nitrate and sodium nitrate, or permanganates such as potassium permanganate. Most preferred oxidizing agents include hydrogen peroxide and methyl ethyl ketone peroxide (MEKPO).
).

Hydrogen peroxide is diluted with water to the specified concentration, applied, and dried. Methyl ethyl ketone peroxide (MEKP)
O) can be diluted with alcohol, ether, MEK, etc., or applied as an undiluted solution and dried. The oxidizing agent coated and dried on the surface of the rolled vapor-deposited product can be left in the form of a "wound roll" for a certain period of time. (9) To accelerate the reaction, the substrate can be left in the following high-temperature atmosphere to an extent that the substrate is not damaged by heat. The above-mentioned fixed time varies depending on the film width and winding tension, but is preferably 12 hours or more.

This means can be used to stabilize the deposited film and then provide the surface with known groups, liquid lubricant layers, and retention layers. In addition, if necessary, packs and
Providing a coat layer is also optional.

Further explanation will be given below based on the implementation.

[Example, comparative example]

Using the winding vapor deposition apparatus shown in Fig. 1, an oblique vapor deposition method was performed on a polyethylene terephthalate substrate with a thickness of 13 μm f).
A magnetic thin film was formed by vapor deposition (Cog5Ni15ratomy). The film width is 700%, and the transport speed is jO
m/min, minimum incidence angle Jj', film thickness 200X, and vapor deposition is performed while introducing 02 gas from IO so that z x i O-' Tor r is achieved. For the rolled vapor-deposited product thus obtained, use commercially available hydrogen peroxide solution! After diluting it thoroughly and applying it on the vapor deposition surface, it was wound up again into a "wound roll" (this will be referred to as sample A).

Also, methyl ethyl ketone peroxide (ME
KPO) was applied and rolled up, and this is called sample B). Furthermore, for comparison, a sample was prepared that was subjected to only the above-mentioned rolling vapor deposition without any post-treatment (this was referred to as sample C). These roles A and B.

C is each full length cooom. In this state, it was left at room temperature and humidity for 3 days. After that, 1 from these 3 samples
Three samples were cut out at 110m x 7j at intervals of 000m (A/~A3, B/-Bj, C/-
Let's call it C.J. The ones with the lowest numbers were cut out at a position close to the core. ) The above desamples were left in a t00c 90% RH atmosphere for a week, and the total magnetic flux amount φm (Mx
/crIL) -Δφm/φm was measured. The results are shown in the table below (the numbers are disappointing).

It can be judged that the smaller the value of this rate of change -Δφmlφm, the better the weather resistance. It can be seen that sample A and sample B have improved weather resistance compared to sample C, which is a comparative example.

〔Effect of the invention〕

By the method of the present invention, metal thin film magnetic recording media with improved weather resistance can be manufactured easily and uniformly.

[Brief explanation of the drawing]

FIG. 1 shows a winding vapor deposition apparatus. ／・・・・・・Vacuum chamber t...Feeding roller t... Cooling drum T... Evaporation source 10...Gas inlet Lco...Take-up roller

Claims (2)

[Claims] (1) After a magnetic metal or alloy thin film is provided on a flexible substrate by a winding vapor deposition method, an oxidizing agent or its diluted solution is applied and dried on the thin film and/or the surface of the substrate opposite to the thin film. 1. A method of manufacturing a magnetic recording medium, the method comprising: (2) The method for manufacturing a magnetic recording medium according to claim (1), wherein the oxidizing agent is hydrogen peroxide or methyl ethyl ketone peroxide.