JPS639021A - Apparatus for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and running property by subjecting a roll coiling a magnetic recording medium of a substrate formed with a ferromagnetic metallic layer to a heat treatment in an atmosphere where oxygen and moisture exist and specifying the surface roughness and coiling tension at the time of coiling. CONSTITUTION:Slight spaces 13 are formed to respective stages of the magnetic recording media of the coiled roll 10 by adjusting the tension onto a base film 1 at the time of coiling and the tape-like magnetic recording media are held in multiple stages of proximity positions via such spaces 13. The roll is disposed in the atmosphere where the oxygen and moisture exist, by which the roll is heat-treated. The oxygen and moisture are uniformly infiltrated and diffused between the surfaces of the ferromagnetic metallic layers 12 of the magnetic recording media and the base films 1 in proximity to the front faces of the ferromagnetic metallic layers. The average surface roughness (Ra) of the substrate surface is, therefore, desired to be in a 0.001mum<=Ra<=0.05mum and the coiling tension T thereof to be in the following range: 1kg/mm<2>. The corrosion resistance and running property of the magnetic recording medium are thus improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for manufacturing a magnetic recording medium, and in particular, after forming a magnetic layer, an oxide film is formed on the magnetic layer while the substrate is wound into a roll. The present invention relates to an apparatus for manufacturing a magnetic recording medium.

[Conventional technology]

A magnetic recording medium in which a ferromagnetic metal layer such as cobalt or a cobalt alloy is formed on a nonmagnetic substrate such as a plastic film has excellent high-density recording characteristics. However, since the metal layer is exposed on the surface of the magnetic recording medium, its corrosion resistance is low, resulting in problems such as a decline in magnetic properties and the growth of corrosion products, which reduces the durability of the medium surface and causes poor running. be. For this reason, several methods have been proposed to prevent deterioration of magnetic properties and improve running performance.

First, in order to improve running performance, it has been proposed to form a protective layer made of a lubricant on the surface of a ferromagnetic metal layer. - When a practical test was carried out under the conditions of 40°C and 80% R9H1 with a magnetic tape in which a protective layer made of lubricant was directly formed on the ferromagnetic metal layer installed in a cassette on a ship, it was found that this magnetic tape After some time, it will cause poor running. When we investigated the cause of this, we found that the coefficient of friction increases, and in some cases, this coefficient of friction exceeds 1.0. In other words, it was found that the lubricating effect was lost in a short period of time due to the growth of corrosion products, and the friction coefficient increased over time.

In addition, in order to improve the wear resistance and corrosion resistance of magnetic recording media, the surface of the ferromagnetic metal layer is heated, thereby reducing the C020
4. Method for forming oxide films such as COx 03 and Coo (Japanese Patent Publication No. 49-29445), by treating a ferromagnetic metal layer in an atmosphere of appropriate temperature and humidity, Co, O, etc. can be formed as an oxide film. Method of forming
025), and furthermore, 1 to the surface of the ferromagnetic metal layer.
Spraying water vapor at 00°C or higher to form crystalline Coo on the surface of the layer.
Method for forming (OH) (JP-A-57-123533
Various methods and devices have been proposed.

[Problem that the invention seeks to solve]

In all of the above-mentioned techniques, a substrate on which a ferromagnetic metal layer is formed is placed in such a way that the surface of the ferromagnetic metal layer is exposed to a predetermined atmosphere. is supplied to the surface of this ferromagnetic metal layer more than necessary, and a Co(OH)z layer is formed on the surface of the ferromagnetic metal layer during or after the treatment, and the corrosion resistance and runnability cannot be significantly improved. In some cases, it may even make things worse.

[Means for solving problems]

The present invention was constructed in view of the above-mentioned problems, and involves winding up a magnetic recording medium as a base on which a ferromagnetic metal layer is formed.
This device is configured to heat-treat the wound magnetic recording medium in an atmosphere containing oxygen and moisture, and the winding tension and surface roughness of the magnetic recording medium are appropriately set when winding the magnetic recording medium. Accordingly, the structure is such that an oxide film can be formed satisfactorily on the ferromagnetic metal layer in the rolled state.

[Effect]

By appropriately setting the winding tension when winding the magnetic recording medium, the surface roughness of the magnetic recording medium, etc., it is possible to prevent excess or deficiency of oxidizing materials such as oxygen and moisture on the surface of the ferromagnetic metal layer of the wound magnetic recording medium. As a result, an oxide film is uniformly formed on the surface of the ferromagnetic metal layer, and sufficient corrosion resistance and runnability are obtained.

[Implementation row]

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, the state of formation of the ferromagnetic metal layer on the substrate will be explained with reference to FIG.

The substrate is a continuously formed film (hereinafter referred to as "base film") 1, which is wound as a raw roll 2. A predetermined tension is applied to the base film 1 unwound from the original roll 2 by a tension roller 3, and the base film 1 is wound around a cylindrical can 6 via guide rollers 4 and 5, and further passed through a guide roller 7.8 and a tension roller. 9 and then wound onto a take-up roll IO. During this time, a ferromagnetic metal made of, for example, a cobalt-nickel alloy is evaporated from the crucible 11, which is an evaporation source located below the can 6, and adheres to the surface of the base film, forming a ferromagnetic metal layer 12 on the base film 1. (See Figure 2). By supplying an oxidizing material such as water vapor to the ferromagnetic metal layer-forming base film wound up as a take-up roll, it is possible to improve the ferromagnetic metal layer as described in detail below. Forms an oxide film on the surface.

First, as the non-magnetic material for forming the base film, for example, in addition to plastic sheets such as polyethylene terephthalate resin, polyimide resin, and polyester resin, non-magnetic metal plates such as aluminum, glass, etc. can be used, and even plastics can be used. Composite materials in which inorganic substances such as carbon fibers are mixed into the substrate are also used.

Examples of ferromagnetic metals containing cobalt as a main component include simple cobalt, cobalt-nickel alloy, and cobalt-nickel alloy.
Cobalt alloys such as chromium alloy, cobalt-nickel+IJn alloy, cobalt-chromium alloy, cobalt-iron alloy, cobalt-phosphorous alloy, cobalt-nickel-chromium alloy, etc. are used.

In the case of the cobalt-nickel alloy, cobalt-nickel-phosphorus alloy, and cobalt-metal-chromium alloy, the nickel content is preferably about 40% by weight or less.

In the case of cobalt-chromium alloys, cobalt-iron alloys, and cobalt-phosphorus alloys, the chromium, iron, and phosphorus contents are preferably about 30% by weight or less.

As the lubricant, for example, a fatty acid-based organic compound, a fluorine-based organic compound, a silicon-based organic compound, etc. are used.

First, as the fatty acid-based organic compound, fatty acids, metal salts of fatty acids, fatty acid esters, fatty acid amides, etc. are used. Specific examples of the fatty acids include myristic acid, palmitic acid, oleic acid, stearic acid, and behenic acid. Examples of these metal salts include lithium salts, sodium salts, calcium salts, magnesium salts, aluminum salts, iron salts, cobalt salts, zinc salts, barium salts, and lead salts.

Examples of fatty acid esters include butyl stearate,
Examples include stearic acid monoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride, and pentaerythol tetrastearate.

Examples of fatty acid amides include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, methylene bisstearic acid amide, and the like.

Examples of fluorine-based lubricants include trichlorofluoroethylene, perfluoropolyether, and perfluoroalkyl polyether. Specific examples of commercially available products include Daiflon #20 manufactured by Daikin Corporation, Krytox M manufactured by DuPont, and Krytox H manufactured by DuPont. Silicone oil is also available as a silicone-based lubricant.

Note that the lubricant layer may be composed only of the above-mentioned lubricant, or the lubricant may be mixed with additives such as liquid paraffin or rust preventive to improve the corrosion resistance of the lubricant layer. It is also possible to do so. Further, the lubricant layer may be formed by coating directly on the oxide film, or may be formed on the oxide film by a transfer method or the like.

While the magnetic recording medium with the ferromagnetic metal layer formed on the base film according to the configuration specifically shown above is wound up into a roll, the nol is heat-treated in an atmosphere containing at least oxygen and moisture. When this is carried out, a cobalt hydrated oxide containing trivalent or higher cobalt is formed on the surface of the ferromagnetic metal layer, and Co(○H) on the surface of the ferromagnetic metal film is formed.
) It was confirmed that it is possible to obtain a magnetic recording medium that suppresses the formation of z, has high corrosion resistance, and has stable running characteristics even under high temperature and high pressure.

This will be explained in more detail below.

By winding a magnetic recording medium consisting of a base film on which a ferromagnetic metal layer is formed into a roll, the base film of the magnetic recording medium and the ferromagnetic metal layer are adjacent to each other in the radial direction of the roll, as shown in Figure 3. do. In this case, by adjusting the tension on the base film during winding, a slight gap 13 is formed between the magnetic recording media in each stage of the winding roll 10, and the tape-shaped magnetic recording medium is A state is reached in which multiple stages of media are located close to each other.

The roll is placed in an atmosphere containing oxygen (which may be atmospheric oxygen) and moisture and is heat treated. As a result, the oxygen and moisture are uniformly infiltrated and diffused between the surface of the ferromagnetic metal layer 12 of the magnetic recording medium and the base film 1 adjacent to the front side of the ferromagnetic metal layer. Therefore, the supply rate of oxygen, moisture, etc. and the reaction rate proceed in equilibrium. Note that this amount of diffusion can be controlled by the surface roughness of the base film serving as the substrate and the tension at the time of winding. in this case,
The average surface roughness (Ra) of the substrate surface is 0.001 μm≦R
a≦0.05μm, maximum surface roughness Rmax) is Rm
It is desirable that a x≦0.5 μm.

Ra<0.001. In Ijm, oxygen and moisture do not diffuse sufficiently in the rolled magnetic recording medium, and Ra>
At 0.05 μm or Rmax > 0.5 μm, the amount of water diffusion is too large, and Co(O
H) A z layer is formed. The smaller the substrate surface roughness, the smaller the tension when winding the substrate to maintain an appropriate gap between each magnetic recording medium, and the larger the substrate surface roughness, the greater the tension when winding. be able to. In this case, if the winding tension is too small, winding irregularities will occur1, whereas if it is too large, cracks or build-up will occur in the ferromagnetic metal layer, so the winding tension T should be within the following range. desirable.

1 kg/w" ≦T ≦5 kg/w" The heat treatment temperature and time vary depending on the heat conduction properties of the substrate, but the higher the temperature, the shorter the treatment time. When polyethylene terephthalate is used as the substrate, the processing temperature is 35°C.
-100°C, preferably 40°C - 90°C. 35℃
If the temperature is below 100° C., there will be no treatment effect, whereas if the temperature is higher than 100° C., the substrate will curl severely and the practicality of the magnetic recording medium after treatment will be extremely reduced.

The inventors have investigated the average surface roughness Ra of the substrate and the time until envelope disturbance occurs when the magnetic recording medium obtained based on the configuration shown above is exposed to temperatures of 40° C. and humidity of 80% R and H. Tests were conducted on the relationship between the winding tension of the substrate and the time until envelope disturbance occurs, and the results shown in the following table were obtained.

First, the relationship between the surface average roughness Ra of the substrate and the time until envelope disturbance occurs is as follows. At this time, the winding tension T of the substrate was 3 kg/mm2, and the processing time was 10
The treatment temperature was 60° C. for 0 hours.

Note that the humidity at this time was 10% R, H.

Table 1 Next, regarding the relationship between the winding tension of the substrate and the time until the occurrence of envelope disturbance, the following results were obtained.

In this case, the average surface roughness Ra was 0.03, the treatment time was 75 hours, and the treatment temperature was 80°C. Moreover, the humidity at this time was 8% R,H.

Table 2 Although the present invention has been explained above using as an example the treatment of a magnetic recording medium constructed by forming a ferromagnetic metal layer on a base film by vapor deposition, the present invention does not relate to any method of manufacturing a magnetic recording medium. It is possible to carry out this method, and it can be successfully carried out for magnetic recording media constructed by sputtering, plating, ion blating, etc. in addition to the above-mentioned vapor deposition method.

〔effect〕

As explained above, the present invention is configured so that a roll wound up with a magnetic recording medium as a base on which a ferromagnetic metal layer is formed is heat-treated in an atmosphere containing oxygen and moisture.
An oxide film can be satisfactorily formed on the ferromagnetic metal layer in the rolled state. In addition, by appropriately setting the winding tension during winding of the magnetic recording medium, the surface roughness of the magnetic recording medium, etc., the surface of the ferromagnetic metal layer of the magnetic recording medium to be wound can have an excess or deficiency of oxidizing materials such as oxygen and moisture. It is possible to form a good oxide film on the ferromagnetic metal layer. Therefore, the corrosion resistance and running characteristics of the magnetic recording medium can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magnetic recording medium manufacturing apparatus showing one embodiment of the present invention, FIG. 2 is a longitudinal section of a magnetic recording medium, and FIG.
The figure is a partial cross-sectional view of a magnetic recording medium wound into a roll. 1...Base film 2...Material roll 10.
... Winding roll 12 ... Ferromagnetic metal layer

Claims (3)

[Claims] (1) In a magnetic recording medium in which a magnetic metal layer is formed on a substrate and an oxide film is formed on the surface of the magnetic metal layer, the magnetic recording medium with the magnetic metal layer formed thereon is oxygenated. and a magnetic recording medium manufacturing apparatus, characterized in that the magnetic recording medium is placed in an atmosphere in which moisture is present, and a heating means is placed on the wound magnetic recording medium. (2) The average surface roughness Ra of the substrate is in the range of 0.002 μm to 0.05 μm, and the maximum surface roughness is 0.5 μm.
A magnetic recording medium manufacturing apparatus according to claim (1), characterized in that: (3) The magnetic recording medium according to claim 1 or 2, characterized in that the winding tension of the base is in the range of 1 kg/mm^2 to 5 kg/mm^2. Manufacturing equipment.