JPH0740359B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film suitable for high density magnetic recording as a magnetic recording layer.

2. Description of the Related Art A magnetic recording medium using a ferromagnetic metal thin film suitable for high-density magnetic recording as a magnetic recording layer has a magnetic recording layer formed by an electron beam evaporation method,
After being formed by a sputtering method or the like, the top coat layer is provided by a solution coating method, a vacuum deposition method or the like and processed into a predetermined size [for example, the Institute of Electronics and Communication Engineers Magnetic Recording Research Group sample, MR81-2 (1981 ), JP-A-57-189331, JP-A-5
7-150136, JP-A-57-179948, JP-A-61-126627
No. 6, JP-A-61-1930, JP-A-61-151835, JP-A-Sho 6
References such as 1-151837).

The importance of the topcoat layer has recently been particularly recognized, and many proposals have been made for materials.

Especially for the purpose of improving durability, diamond-like carbon film,
Attention has been focused on plasma polymerized film, SiO ₂ sputtered film, MoS ₂ sputtered film and laminated type of lubricant.

Lubricant coating is often carried out by a wet solution coating method, which has better mass productivity than the organic vapor deposition method. In this method, optimization is attempted depending on the combination of the lubricant and solvent and the drying conditions.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned configuration, when repeatedly used in a high temperature and high humidity environment, the amount of lubricant decreases and the sufficient lubricating action disappears, so noise increases and the still characteristic deteriorates. Therefore, there is a problem that the dropout increases when stored at high temperature and high humidity for a long time after repeated use, and improvement is desired. The present invention has been made in view of the above circumstances, and provides a manufacturing method suitable for obtaining a magnetic recording medium having improved durability and weather resistance.

Means for Solving the Problems In order to solve the above-mentioned problems, in the method for producing a magnetic recording medium of the present invention, a lubricant is arranged on a ferromagnetic metal thin film arranged on a polymer film by a solution coating method. After that, ozone treatment is performed.

Action The method for producing a magnetic recording medium of the present invention has the above-described configuration, in which the lubricant and the ferromagnetic metal thin film undergo a reaction to firmly adhere to each other, and the degree of oxidation of the ferromagnetic metal thin film by the oxidizing action of ozone. Since it reinforces the weak portion, the weather resistance is also improved, and its action is considered to be accompanied by the reactive adhesion of the lubricant, so the degree of improvement is large.

Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings. The figure shows an ozone treatment apparatus used for carrying out the present invention. In FIG. 1, reference numeral 1 denotes a processing substrate in which a ferromagnetic metal thin film is arranged on a polymer film and a lubricant is arranged thereon by a solution coating method. Polymer films include polyethylene terephthalate, polyphenylene sulfide,
Polyimide, polycarbonate, etc. are suitable, and as the ferromagnetic metal film, Co-Cr, Co-Ti, Co having a thickness of about 0.05 to 0.2 μm formed by electron beam evaporation method, sputtering method or the like is used.
A high coercive force film such as -Mo, Co-O, Co-Ni, Co-Fe, Co-Cr-Nb, Co-Ni-O is used. The solution coating method is a method in which a lubricant is dissolved in a dispersant, which is then coated with a reverse roll coater, bar coater, etc., and dried. There is no special limitation, either alone or as a mixture.

Reference numeral 2 is a feeding shaft, 3 is a winding shaft, 4 is a coating head, and 5 is a drying furnace, and a hot air drying method is suitable. Reference numeral 6 is an ozone treatment tank, and 7 is an electron beam generator. 8 is a rotating roller, the ozone generation method, by accelerating the electron beam, taken out from the titanium foil into the atmosphere,
The method is not limited to the method of producing ozone from oxygen in the air, and there is no difference between the methods, such as by air discharge.

However, it is needless to say that the effect of electron beam irradiation can be added depending on the conditions, but the effect of ozone is large.

Examples will be described more specifically. On a polyethylene terephthalate film with a thickness of 12 μm, 2 × 10 ^-4 (To
rr) in oxygen, Co-Ni (Ni, 20wt%) with a minimum incident angle of 36
Obliquely deposited at a rate of 0.15 μm and a coercive force of 1000 (Oe) Co-Ni-
After placing the O film and drying the stearic acid dissolved in toluene,
A tape A was prepared by applying 4 mg / m ² and subjected to ozone treatment, and a tape B was prepared without ozone treatment.
The ozone treatment was carried out by extracting an electron beam accelerated to 200 KV from a 15 μm thick titanium foil at 0.04 mA / cm ² and exposing it to the generated ozone atmosphere at 50 m / min. The ozone concentration was 6000 ppm.

On a polyethylene naphthalate film with a thickness of 16 μm, 0.16 μm Co-Cr (Cr20.6
wt%) Perpendicular magnetic film [perpendicular coercive force 590 (Oe)] is placed, and methyl lignocerate dissolved in methyl isobutyl ketone is applied and dried to a dry amount of 6 mg / m ^2, and ozone treatment is applied to tape A. Tape C was treated under the same conditions as above, and tape D was an untreated product.

Tapes A to D were repeatedly recorded and reproduced with a commercially available 8 mm video. In the environment of 45 ° C. and 87% RH, the number of passes in which the screen was disturbed due to the increase in jitter was 68 in the case of tape B and 73 in the case of tape D.
It was not recognized at all even after repeated 0 passes.

Moreover, when the dopout was measured after storing at 60 ° C and 80% RH for 4 months, tape A was
2.2 times, Tape B 16.9 times, Tape C 1.8 times, Tape D
Was 24.5 times.

Also, tape that has been run 50 times at 50 ° C and 80% RH should be used at room temperature and humidity.
The C / N and still characteristics were compared with the initial values.

C / N is the signal-to-noise ratio of the luminance signal, and the head is a metal-in-gap type. Still output is 3 (dB) playback output
It is a comparison at a fixed price.

The C / N changes of the tapes A, B, C, D are O (dB), -3.9 (dB), O
(DB), -4.7 (dB), still characteristics are 98 minutes, 17 minutes, 95 minutes,
It was 21 minutes.

EFFECTS OF THE INVENTION As described above, according to the present invention, there are excellent effects such as use at high temperature and high humidity, and a large amount of magnetic recording media having improved storage characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an ozone treatment device used in an example of the present invention. 1 ... Processed substrate, 4 ... Coating head, 5 ... Drying furnace, 6 ... Ozone treatment tank.

Claims (1)

[Claims] 1. A method for producing a magnetic recording medium, which comprises arranging a activating agent on a ferromagnetic metal film on a polymer film by a solution coating method, followed by ozone treatment.