JPH0950625A - Manufacturing method of magnetic recording medium - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a magnetic recording medium excellent in magnetic characteristics, durability and corrosion resistance. Kind Code: A1 A method of manufacturing a magnetic recording medium, comprising a step of providing a metal magnetic thin film on a support by dry plating, and a step of immersing the support provided with the metal magnetic thin film in an oleophilic liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium.

[0002]

In a magnetic recording medium such as a magnetic tape, a magnetic layer provided on a non-magnetic support is not a coating type using a binder resin because of a demand for high density recording. , A metal thin film type that does not use a binder resin has been proposed. That is, vacuum deposition,
It is well known that a magnetic recording medium having a magnetic layer formed by dry plating means such as sputtering or ion plating has been proposed. And since this kind of magnetic recording medium has a high packing density of the magnetic material,
This is suitable for high-density recording.

An apparatus for manufacturing a magnetic recording medium by such dry plating means is generally constructed as shown in FIG. In FIG. 2, 21 is a cooling can roll,
22a is a supply side roll of the polyethylene terephthalate (PET) film 23, 22b is a winding side roll of the PET film 23, 24 is a crucible, 25 is a magnetic metal, and 26 is a vacuum chamber. Then, after the vacuum chamber 26 is evacuated to a predetermined vacuum degree, the electron gun is operated to evaporate the magnetic metal 25 in the crucible 24, and the evaporated particles of the magnetic metal 25 are deposited on the PET film 23 ( A magnetic recording medium is manufactured by vapor deposition.

By the way, when manufacturing a metal thin film type magnetic recording medium with such an apparatus, it was attempted to supply oxygen to the vapor deposition portion of the magnetic particles to improve the magnetic characteristics. That is, it is proposed that oxygen be supplied in the direction opposite to the traveling direction of the PET film 23 (Japanese Patent Publication No.
1-56563). And this one is
It had some features.

However, it has gradually become clear that the above proposal is not satisfactory. That is, although the oxygen gas is blown, the amount of the oxygen gas blown cannot be increased in the film formation step in vacuum, and therefore the amount becomes sparse, and the portion where the oxide film is formed and the portion where it is not Since it is formed like spots and a uniform film is not formed, it has been found that the magnetic properties and durability are not uniform and are not as excellent as expected. When the amount of oxygen gas sprayed is increased, the oxygen concentration on the surface of the magnetic layer is high, the oxygen concentration is low on the side close to the PET film, a concentration gradient is created in the oxygen content, and diffusion of oxygen occurs over time, causing saturation. It has also been found that a decrease in magnetic flux density occurs.

[0006] As a result of earnestly carrying out research on such a point, it was possible to obtain a revelation that a uniform oxidation treatment may be possible by immersing in a lipophilic liquid and utilizing dissolved oxygen. As a result of attempting this technical idea, this was more successful than expected. The present invention has been achieved based on such findings, and has the magnetic characteristics,
An object of the present invention is to provide a magnetic recording medium having excellent durability and corrosion resistance.

[0007]

The object of the present invention is to provide a step of providing a metal magnetic thin film on a support by dry plating, and a step of immersing the support provided with the metal magnetic thin film in a lipophilic liquid. And a magnetic recording medium manufacturing method. As the liquid used in the present invention, for example, a liquid having a hydrocarbon group such as an alkyl group (aliphatic hydrocarbon group) such as benzene, toluene, methyl ethyl ketone, or a phenyl group (aromatic hydrocarbon group) is preferable.

The immersion time for immersion in a liquid varies depending on the type of liquid (particularly, the amount of dissolved oxygen), but is about 10 seconds to 50 hours, preferably about 30 minutes to 20 hours, and more preferably about 10 seconds. It is about 1 to 5 hours. Further, in the above invention, when the support provided with the metal magnetic thin film is immersed in a liquid, supplying an oxidizing gas into the liquid, applying an ultrasonic wave, and It is preferable to heat the liquid, for example, to about 15 ° C to 70 ° C.

It is preferable that the metal magnetic thin film is provided as described above, and after the immersion treatment, a protective film, for example, a carbon film (particularly, a diamond-like carbon film) is provided on the metal magnetic thin film. This protective film has high adhesion strength to the metal magnetic thin film that has been subjected to the immersion treatment, that is, the adhesion strength is higher than that of the protective film provided on the metal magnetic thin film without undergoing the immersion treatment, and it is highly durable. there were.

[0010]

1 is a schematic view of an apparatus for manufacturing a magnetic recording medium according to the present invention. In the figure, 1 is a cooling can roll, 2a is a supply side roll of the support 3, 2b is a winding side roll of the support 3, 4 is a protection plate, 5 is a crucible, 6 is a magnetic metal, 7 is oxygen gas The supply nozzle 8 is a vacuum chamber.

The support 3 may be magnetic or non-magnetic, but is generally non-magnetic. For example, polyester such as PET, polyamide, polyimide, polysulfone, polycarbonate, olefin resin such as polypropylene, cellulose resin, polymer material such as vinyl chloride resin, inorganic material such as glass or ceramic, aluminum alloy A metal material such as An undercoat layer for improving the adhesion of the magnetic layer (magnetic thin film) is provided on the surface of the support 3 as needed. That is, by appropriately roughening the surface roughness, the adhesion of the magnetic thin film formed by the oblique deposition method is improved, and the surface roughness of the magnetic recording medium surface is moderated to improve the running property. , For example, the thickness including particles such as SiO ₂ is 0.0
The undercoat layer is formed by providing a coating film having a thickness of 05 to 0.1 μm.

As the magnetic metal with which the crucible 5 is filled,
For example, in addition to metals such as Fe, Co, and Ni, a Co-Ni alloy, a Co-Pt alloy, a Co-Ni-Pt alloy, a Fe-C
o alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe
-Co-B alloy, Co-Ni-Fe-B alloy, Co-C
Examples thereof include r alloys and alloys containing a metal such as Al.

Reference numeral 9 denotes a liquid tank provided adjacent to the vacuum tank 8, and the support 3 is configured to meander in the liquid tank 9 so that it can travel. In the apparatus configured as described above, after the vacuum chamber 8 is evacuated to a vacuum degree of about 10 ⁻⁴ to 10 ⁻⁶ Torr, for example, 2 × 10 ⁻⁵ Torr, resistance heating, high frequency heating, electron beam heating, etc. To evaporate the magnetic metal (Co) 6 in the crucible 5 to 400 to 20000Å, for example 180 to the support 3 such as a PET film.
A metal thin film type magnetic recording medium is manufactured by depositing a 0 Å-thickness Co magnetic metal 6. A small amount of oxygen is blown from the oxygen gas supply nozzle 7 during the oblique deposition of the Co magnetic metal particles. As a result, a magnetic column is formed on the magnetic metal thin film. When the magnetic characteristics of the Co magnetic metal thin film thus obtained are examined, the coercive force Hc is 1200 Oe and the saturation magnetic flux density Bs is 7.
It was 000G.

In this way, the magnetic thin film is formed, and in the process of winding the magnetic thin film on the winding roll 2b, the support 3
The air (oxygen) is blown into the liquid tank 9 filled with toluene, and is made to run while meandering.
The liquid temperature is 15 to 7 over time (3 hours in this embodiment).
After being immersed in toluene at 0 ° C. (30 ° C. in this embodiment), it is taken out from the liquid tank 9, dried, and then wound around the winding side roll 2b.

After that, the winding roll 2b wound up was loaded into an ECR microwave CVD apparatus, and this apparatus was operated to deposit a diamond-like carbon film having a thickness of 60 Å using methane as a raw material source on the magnetic thin film. Form. After that, a back coat coating material in which carbon black having an average particle diameter of 20 nm and a binder resin composed of a vinyl chloride resin and a urethane prepolymer are dispersed is applied to the support 3 on the side opposite to the magnetic layer by a direct gravure method. It is applied to provide a back coat layer having a dry thickness of 0.5 μm.

Fluorine perfluoropolyether (grade: FOMBLIN ZDIAC carboxyl group modified, manufactured by Nippon Montedison Co., Ltd.) was diluted to 0.1% in a fluorine inactive liquid (Fluorinert, FC-84, Sumitomo 3M). -Apply the dispersed coating material on the magnetic surface by a die coating method so that the thickness after drying is about 20Å, and dry at 70 ° C.

After that, a magnetic tape (Example 1) was obtained by slitting to a predetermined width. Further, the magnetic tape (Example 2) was carried out according to the first embodiment except that the liquid temperature was 15 ° C. and the liquid residence time was 10 hours in the first embodiment.
I got In the first embodiment, the liquid temperature is 60
A magnetic tape (Example 3) was obtained in the same manner as in the first embodiment except that the temperature was held at 40 ° C. in the liquid for 40 minutes.

A magnetic tape (Example 4) was obtained in the same manner as in the first embodiment except that benzene was used instead of toluene in the first embodiment. In addition, the first
In the embodiment, according to the first embodiment except that oxygen is blown at a rate of 500 cc / min from the nozzle 10 provided for blowing air (oxygen) into the liquid tank 9 and the residence time in the liquid is 90 minutes. Then, a magnetic tape (Example 5) was obtained.

Further, in the first embodiment described above, oxygen is blown at a rate of 1000 cc / min from the nozzle 10 provided for blowing air (oxygen) into the liquid tank 9, except that the residence time in the liquid is set to 60 minutes. Is performed according to the first embodiment,
A magnetic tape (Example 6) was obtained. Further, in the above-described first embodiment, ultrasonic waves are applied to toluene in the liquid tank 9 using an ultrasonic oscillator of 20 kHz, and the residence time in the liquid is set to 2 hours. A magnetic tape (Example 7) was obtained.

In the first embodiment, when the Co magnetic metal thin film is obliquely deposited, the amount of oxygen from the oxygen gas supply nozzle 7 is adjusted so that the coercive force Hc is 1500 Oe and the saturation magnetic flux density Bs is 5000 G. did. After that, a magnetic tape (Comparative Example 1) was obtained by performing the process according to the first embodiment except that the step of dipping in toluene was omitted. Further, a magnetic tape (Comparative Example 2) was obtained by the same procedure as in the first embodiment except that ethanol (hydrophilic liquid) was used instead of toluene in the first embodiment.

[Characteristics] With respect to the magnetic tapes obtained in the above examples, coercive force, saturation magnetic flux density, durability, and corrosion resistance were examined. The results are shown in Table 1 below. Table-1 Coercive force Saturation magnetic flux density Durability Corrosion resistance (Oe) (G) (dB) (%) Example 1 1490 5600 -0.9 2 Example 2 1500 5550 -0.8 2 Example 3 1530 5520- 0.5 2 Example 4 1470 5600 -0.7 2 Example 5 1550 5500 -0.5 1.5 Example 6 1580 5470 -0.4 1.5 Example 7 1540 5500 -0.7 2 Comparative Example 1 1500 5000 -1.5 5 Comparative Example 2 1630 4360 -2.4 9 * Durability is indicated by a decrease in reproduction output after still reproduction for 3 hours. * Corrosion resistance is 30 at a temperature of 60 ° C and a humidity of 90% RH. This is indicated by the decrease in the saturation magnetic flux density after being left for a day. This shows that the magnetic properties can be improved when the magnetic thin film is immersed in a lipophilic liquid (hydrophobic liquid). And Also in durability and corrosion resistance are exhibited excellent features.

On the other hand, the features of the present invention have not been fully exhibited by the conventional method of only blowing oxygen during film formation. Further, the samples of Example 1 and Comparative Example 1 were examined by Auger electron spectroscopy immediately after the magnetic tape was manufactured and after the corrosion resistance test. The results are shown in FIGS.
5,6.

According to this, according to the present invention, as can be seen from the comparison between FIG. 3 (Auger electron spectroscopic analysis spectrum immediately after the magnetic tape is manufactured) and FIG. 4 (Auger electron spectroscopic analysis spectrum after the corrosion resistance test). , While no significant change in the oxygen distribution in the magnetic film is observed,
In Comparative Example 1, as can be seen from the comparison between FIG. 5 (Auger electron spectroscopic analysis spectrum immediately after magnetic tape production) and FIG. 6 (Auger electron spectroscopic analysis spectrum after corrosion resistance test), There is a large variation in the distribution. Even from now on, the present invention will be
It has excellent durability and corrosion resistance, and it can be seen that the deterioration of magnetic properties is small.

[0024]

According to the present invention, a high-performance magnetic recording medium can be obtained in which the effect of improving the magnetic characteristics and the effect of improving the durability and the corrosion resistance are remarkable.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a magnetic recording medium manufacturing apparatus according to the present invention.

FIG. 2 is a schematic explanatory diagram of a conventional magnetic recording medium manufacturing apparatus.

[Figure 3] Auger electron spectroscopy analysis spectrum

Fig. 4 Auger electron spectroscopy analysis spectrum

Figure 5: Auger electron spectroscopy spectrum

FIG. 6 Auger electron spectroscopy analysis spectrum

[Explanation of symbols]

 1 Cooling Can Roll 2a Supply Side Roll 2b Winding Side Roll 3 Support 5 Crucible 6 Magnetic Metal 7 Oxygen Gas Supply Nozzle 8 Vacuum Tank 9 Liquid Tank 10 Nozzle

Claims (5)

[Claims] 1. A magnetic recording medium comprising: a step of providing a metal magnetic thin film on a support by dry plating means; and a step of immersing the support provided with the metal magnetic thin film in an oleophilic liquid. Manufacturing method. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein an oxidizing gas is supplied into the liquid while the support provided with the metal magnetic thin film is immersed in the liquid. 3. The method for producing a magnetic recording medium according to claim 1, wherein ultrasonic waves are applied while the support provided with the metal magnetic thin film is immersed in the liquid. 4. The method of manufacturing a magnetic recording medium according to claim 1, wherein the liquid is heated while the support provided with the metal magnetic thin film is immersed in the liquid. 5. The method for producing a magnetic recording medium according to claim 1, wherein the liquid is a liquid having a hydrocarbon group.