JPH0414619A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high reliability by washing the surface of a polymer film with jet flow of a solvent and then forming a ferromagnetic metal thin film thereon. CONSTITUTION:On a polymer film 1 such as polyethyleneterephthalate, polyethylenenaphthalate, etc., a fine particle coating layer 2 is formed by dispers ing a water-soluble polymer and fine particles, applying this dispersion liquid, drying and stretching. On the coating layer 2, one or more layers of ferromagnet ic metal thin films 3 such as Co-Ni, Co-Cr, etc., are formed by electron beam vapor deposition or sputtering into or more layers. Further on this metal thin film 3, a protective lubricating layer 4 comprising a combination of SiOx, TiOx, WCx, carbon or plasma polymn. film, and fatty acid and perfluoropolyether. Thereby, the obtd. medium is suitable for high-density recording/reproducing without signal dropout and with high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium having a magnetic recording layer made of a ferromagnetic metal thin film suitable for high-density magnetic recording.

Background of the Invention In recent years, recording density has improved dramatically, and ferromagnetic metal thin films have been increasingly used as magnetic recording layers [for example, IEE Transactions on Magnetics (IE
EE Transactions on Magnet
ics) Vol, MAG-20, ff15 PP82
4-826 (1984)], a magnetic tape in which Co--Ni is obliquely vapor-deposited on a polyethylene terephthalate film in an oxygen atmosphere has been put to practical use in video applications and is attracting attention.

Problems to be Solved by the Invention However, in the magnetic tape described above, since the ferromagnetic metal thin film has a thickness of only about 0.2 μm, the surface shape is directly reflected in the polymer film used. Therefore, it is of course necessary to form a polymer film without damaging the surface.
Post-processing also involves processing in a clean room and using ultrasonic energy to remove adhering dust.

However, since the overall technology has not yet reached a level that can ensure a high error rate with higher density recording, there is a desire for improvement in the technology for eliminating the causes of errors. The present invention was made in view of the above-mentioned circumstances, and provides a method for manufacturing a magnetic recording medium with a good error rate even when performing high-density recording.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a magnetic recording medium of the present invention is such that a ferromagnetic metal thin film is formed after solvent jet cleaning the surface of a polymer film. be.

Operation The method for manufacturing a magnetic recording medium of the present invention has the above-described structure, so that adhered foreign matter that has been difficult to remove in the past can be removed, and the nucleus of unnecessary protrusions that can cause errors can be reduced, resulting in a magnetic recording medium with fewer errors. Recording media can now be manufactured.

Example Examples of the present invention will be described in detail below.

E Example IJ FIG. 1 is an enlarged cross-sectional view of a typical magnetic recording medium manufactured according to the present invention. In FIG. 1, 1 is a polymer film such as polyethylene terephthalate, 2 polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyimide, etc., and 2 is a fine particle coating layer.
A mixture of a water-soluble polymer and fine particles mixed and dispersed and formed into a shape by coating, drying and stretching during film formation is often used, but it is not limited to this. Of course, it is also good.

3 is Co--Ni, Co--Cr, Co-0, Co--C formed by electron beam evaporation, sputtering, or the like.

Co-Ti, Co-Mo, Co-Pt, Co-B, C.

A ferromagnetic metal thin film such as Ni-0 is not limited to a single-layer structure, but may have a multi-layer structure, and the direction of the easy axis of magnetization can also be adjusted in particular to IIJ.
There are no limits. 4 is a protective lubricating layer, which is SiOx.

It is a suitable combination of TiOx, T1Cx, WCx, carbon, Brahma polymer film, fatty acids, perfluoropolyether, etc., and can be configured to be accessible on both sides by providing a back coat layer and the form of the magnetic tape or magnetic disk. Of course.

In manufacturing the magnetic recording medium having the above-described configuration according to the present invention, it is necessary to avoid the conventional methods of removing attached foreign matter using a clean air stream and performing auxiliary glue noning using a combination of ions and ultrasonic vibrations. It's not a thing.

Next, solvent jet cleaning will be explained in detail.

The solvent used for solvent jet cleaning is alcohol, which is achieved by spraying a solvent jet and, if necessary, drying air, while moving the film to be cleaned from the unwinding side to the winding side.

For ketones, fluorocarbons, etc., the injection pressure is 2 to 1° (kg
/ c! ) is preferred. Solvent recovery, combustion treatment, etc. may be performed using current or improved pollution prevention technology. The solvent injection jet is not limited to one stage, but may be multiple stages (of course, it is performed in a clean room).

Examples of the present invention will now be described in more detail in comparison with comparative examples.

When forming a film on a polyethylene terephthalate film with a thickness of 10 μm, S of 20 OA in diameter was added to the water-soluble polymer.
i After dispersing and applying O2 fine particles, it is dried and stretched, and in addition to the earthworm-like shape, particulate protrusions are formed on average at 20 (ke/μ2).
), a horizontally long nozzle (70 cm in length) with small holes of 0.15 mφ in diameter arranged at intervals was used as a solvent jet nozzle, and dry air was sprayed at 110°C for 2 hours.
Cleaning was performed by spraying at a rate of 0 i/min while changing the solvent conditions and the number of nozzle stages.

The solvent used was a 0.2 μrn final filter, and the dry air was filtered using a 0.3 μm final filter to remove foreign substances. Comparative examples used one treated with an ultrasonic ionic cleaner and one untreated.

In both Examples and Comparative Examples, a cylindrical can with a diameter of 1 m was cured, and Co-Ni (Co 80 wt%) was coated with a thickness of 15 μm.
, 8 X 10-5 (Torr) of oxygen at a minimum incident angle of 35 degrees, and on top of that, DuPont's (7) KRYTOX143AC was deposited at 35 (u/nf).
), and a polyurethane-based back coat layer containing 6% by weight of carbon with a diameter of 0.07 μm and 0.064 μm as a filler was provided to obtain a magnetic tape with a width of 8 mm. Each tape was recorded on a high band 8mm video (NiN EV-89
00) (7) Table 1 shows the results of comparing the error rates of PCM in LP mode.

(Margins below) [Example 21 Another means for solving the problem is to form a first ferromagnetic metal thin film on a polymer film, perform a burnishing treatment, and apply a second ferromagnetic metal thin film on top of the burnishing process. A thin metal film is formed. The method for manufacturing a magnetic recording medium of the present invention has the above-described structure, so that the ferromagnetic metal thin film does not have protrusions that cause errors (at the same time, the second ferromagnetic metal thin film suppresses the occurrence of pinholes). Compared to the conventional burnishing process performed after forming a ferromagnetic metal thin film, the source of error can be minimized.Hereinafter, embodiments of the present invention will be described in more detail.

A ferromagnetic metal thin film is formed on a polymer film such as polyethylene terephthalate or polyethylene naphthalate.

The ferromagnetic metal thin film may be formed by a high frequency sputtering method, an electron beam evaporation method, an ion blating method, etc. The thin film may be Co-0, Co-Ni, Co-Cr,
Co-Ta, Co-W, Co-Mo.

Co-Pt'-0, Co-Ni-0, Co-B-Pt-
Any value such as 0 is acceptable. Preferably, the thin film ranges from 500A to 150OA. After forming the thin film, use an abrasive to
A so-called vanishing process is performed. The processing atmosphere may be under reduced pressure or in the air (the abrasive material may be composed of your own, but if you use a commercially available abrasive material, it is best to use a finer material of 5000 or more. You can choose. After the vanishing treatment, the original film is formed. The film thickness, material, and manufacturing method can be selected from those mentioned above. Next, a protective lubricating layer and, if necessary, a back coat layer are applied. It may be processed into a tape or disk shape.

By using the above method, the second ferromagnetic metal thin film does not contain large protrusions that may cause errors, and the ferromagnetic metal thin film portion removed by burnishing becomes approximately 1/2 the thickness of the magnetic recording layer. This will result in fewer errors.

The second embodiment of the present invention will be described in more detail below in comparison with a comparative example.

20 pieces/μ2 of 5i02 particles with a diameter of 12OA were applied onto a polyethylene naphthalate film with a thickness of 81 μm, and Co-N was applied along a cylindrical can with a diameter of 1 m.
i (Co: 80wt%) with a minimum incident angle of 40 degrees, 8
Electron beam evaporation was performed in oxygen at X 10-5 (Torr) while changing film thickness conditions. After that, a burnishing process was performed using an abrasive. Condition A is the use of No. 9000 abrasive at a speed of 0.4 (m/win) and a pressure of 0.5 (kg/csf).
, contact area 50 cd, condition B is the same as condition A except that the abrasive of No. 15000 is used, and condition C is the same as condition B, with a pressing force of 0.7 (kg/cat) and a contact area of 80 cj.
In both cases, a film with a vapor-deposited film having a width of 40 (!II) was moved at a speed of 70 (m/-1n).
1 (Co: 80wt%) at a minimum incidence angle of 44 degrees, 6X10
Electron beam evaporation was performed in oxygen at -5 (Torr) with varying film thickness conditions, and then perfluoropolyether "Fomblin Z-25" manufactured by Montegisson was deposited at 35 (w)
/d) was coated, and a back coat layer of 0.45 μm in which 16 parts by weight of carbon black was applied to 100 parts by weight of polyester resin was arranged to form magnetic tapes each having a width of 8 mm.

In the comparative example, the burnishing treatment was performed after two vapor depositions, and the burnishing treatment was not performed. Table 2 shows the conditions and dropout in LP mode.

(Margins below) Of course, the data shown in Table 2 can be further improved by combining it with Example 1, and its effectiveness becomes clear when the density is increased.

Effects of the Invention As described above, the present invention has the excellent effect of providing a highly reliable magnetic recording medium with extremely few signal dropouts even when subjected to high-density recording and reproduction.

FIG.

1...Polymer film, 2...Fine particle coating layer, 3...Ferromagnetic metal thin film, 4...
・Protective lubricant layer.

Claims (2)

[Claims] (1) A method for producing a magnetic recording medium, which comprises forming a ferromagnetic metal thin film after cleaning the surface of a polymer film with a solvent jet. (2) A method for manufacturing a magnetic recording medium, which comprises forming a first ferromagnetic metal thin film on a polymer film, performing a burnishing treatment, and then forming a second ferromagnetic metal thin film thereon.