JPS62185243A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve repetitive durability and to uniformly obtain the performance by disposing vapor deposited films on both faces of a high-polymer film, forming a thin ferromagnetic metallic film on one face thereof, immersing the film into a lubricant soln. and drying the same. CONSTITUTION:The film to be treated which is the high-polymer film 1 disposed with the vapor deposited films 3 on both faces thereof and is formed with the thin ferromagnetic metallic film 2 on at least one face is so constituted as to be maintained in the curvature state of a 2-5mm range and to be immersed in the lubricant film 8 then to be dried. A web 7A to be treated consists of the high-polymer film 1, the thin ferromagnetic metallic film 2 and the vapor deposited film 3. Spaces are formed by bending stress in the fine crystals constituting the vapor deposited film 3 and the lubricant soln. 8 is substantially intruded into such spaces and therefore, the magnetic recording layer having the good self-recovering characteristic of the lubricant is obtd. Mass production of the magnetic recording medium having the improved durability is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium using a ferromagnetic metal thin film as a magnetic recording layer.

BACKGROUND OF THE INVENTION In recent years, with the increasing demand for higher density magnetic recording media, there has been a trend toward tape-shaped and disk-shaped magnetic recording media that have a magnetic recording layer made of a ferromagnetic metal thin film.

A method for manufacturing a magnetic recording medium of this type includes forming a magnetic recording layer on a polymer film by electron beam evaporation, forming a protective lubricant layer on the magnetic recording layer by a solution coating method, a vacuum evaporation method, etc. Generally, a back layer is applied as needed and processed into a predetermined shape.

In particular, unlike coating-type magnetic layers, a lubricant cannot be included in the magnetic layer, so surface treatment is required to improve the wear resistance and runnability of the ferromagnetic metal thin film and to reduce changes over time such as oxidation. is important.

Therefore, methods have been devised to improve the purity of the organic solvent used for coating, such as freon, methyl ethyl ketone, 3-methylhexane, etc., and to perform corona treatment before coating. [For example, Japanese Unexamined Patent Publication No. 59-113527] Problems to be Solved by the Invention However, the above-mentioned configuration does not have sufficient performance in terms of durability for repeated recording and reproduction when using an alloy head. cannot be obtained uniformly over a large area, and improvements are desired. The present invention has been made in view of the above-mentioned circumstances, and provides a manufacturing method suitable for mass-producing magnetic recording media with improved repeat durability.

Means for Solving the Problems In order to solve the above problems, the method for producing a magnetic recording medium of the present invention includes disposing vapor deposited films on both sides of a polymer film, and forming a ferromagnetic metal thin film on at least one surface. The film to be processed is kept in a curvature state ranging from 2 to 6H, immersed in a lubricant solution, and dried.

Function: In the method of manufacturing a magnetic recording medium of the present invention, the microcrystals forming the deposited films form gaps due to bending stress, and the lubricant solution sufficiently penetrates into the gaps, so that the self-healing property of the lubricant is improved. A magnetic recording layer with good quality can be obtained, and magnetic recording media with improved durability can be produced in large quantities.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of a magnetic recording medium that can be obtained by the manufacturing method of the present invention. In FIG. 1, 1 is a polymer film, 2 is a ferromagnetic metal thin film, 3 is a vapor deposited film, and 4.
5 is a lubricant layer.

FIG. 2 shows a lubricant dipping device. In Figure 2, 6 is a roller with a radius of 2 to 4 cuts, 7A is the web to be processed, and the first
In the cross-sectional view of the figure, 7A consists of 1.2°3. 7B is provided with 4,4. 8 is a lubricant solution, and e is a lubricant solution tank.

FIG. 3 is an explanatory diagram of the present invention. , the amount of infiltration into the gaps between the columnar crystals 10 is negligible.In comparison, in the example of the present invention shown in FIG. 14 is infiltrated.

This situation is the same for the other vapor deposited layer. 1
5.16 indicates a polymer film 〇 If the radius of the roller is less than 21fi1, the bending stress will become too large and cracks will occur in the ferromagnetic metal thin film, creating a risk of forming parts that will deteriorate durability. Therefore, a radius of 2 km or more is preferable, and if the radius is 611 II+ or more, the phenomenon of penetration into the gap becomes uneven, and as a result, uniform durability cannot be obtained as described later.

Therefore, it can be said that a preferable value for the radius of the roller is in the range of 2mm to 6fi.

The details will be described below with specific numerical values.

Go was electron beam evaporated onto a polyethylene terephthalate film with a thickness of 7.6 prn along a cylindrical can with a diameter of 1 m at a minimum incident angle of 43 degrees in oxygen at 4 x 10 = (Torr) to a thickness of 0.6 prn. A ferromagnetic metal thin film of 16 μm and a coercive force of 1060 (Oe) is formed, and a SiO film of 0.15/l1 m is formed on the other side with a diameter of ω (7).
A web to be treated was prepared by electron beam evaporation with a nearly vertical component within an incident angle of 10 degrees along a cylindrical can.
Prepare 12 rollers each of 6+a+ and 10 yen, place the conveyance system in a tank containing a lubricant solution 901, and immediately after exiting the 0 tank treated at a feed rate of 1204 and n, the temperature is 110°C.
It was dried with. The solution concentration was kept constant at 1300 pI)m (alcohols, ketones, etc. were used as the solvent), and the liquid temperature was kept constant at 40°C. In addition, as a conventional method, two rollers with a radius of 80 wm were prepared and a comparative experiment was conducted.

The tape obtained by slitting the tape from 16mm wide and 100mm long to a width of 8#II+ was arbitrarily extracted from 10 rolls of 50m, and the stell life was measured using an 8mm video tape recorder. For still measurement, 10 arbitrary tape positions were selected. The table below shows the average value, maximum, and minimum values organized by type of lubricant and radius as a parameter. Still condition is tension 20
y, environment: 10°C, 16% RH.

As is clear from the table above, when processing is performed using a roller system with a radius of 2 to 5 m, there is almost no variation in still life, but at 6 m or more, the variation increases and the average value decreases. It can be seen that there is a trend.

The stability of the coefficient of dynamic friction was investigated using tapes Nos. 2 and 6 as representative examples. In the repeated driving mode on the deck,
The coefficient of dynamic friction after 300 passes and 6oo passes was 1.2 times and 1.33 times the initial value for No.2, but N
o, 6, the increase was 2.3 times and 5.9 times.

In addition, when recording and reproducing using a composite ring head with ferrite that has a sendust sputter section only near the gear, the critical number of passes at which the output fluctuates by 3 dB or more is observed at 20°C and 6o%RH. No. 2 is 820 passes,
No. 6 is 290 passes.

At 40℃90%RH, No.2 passes 776 times, pJo
.

6 was 248 passes.

As described above, the tape obtained by the method of the present invention has excellent durability and good uniformity. Also, the tape has a radius of 1.5 mm.
A similar tape was constructed using a roller system, but this one
Although the dynamic friction coefficient showed stability close to that of the present invention, the signal-to-noise ratio deteriorated with repeated use, and the variation in still life tended to increase.

In addition, although the Go-Ni-0 obliquely deposited film was used in the example, Go-Or, Co-0, Co-Cr-
Nb, Go-W.

It may be a perpendicularly magnetized film such as Co--Mo, or another obliquely deposited film.

In addition, even if it is in the form of a disk instead of a magnetic tape, the lubricant immersion effect on the ferromagnetic metal thin film side remains, so the practicality can be sufficiently increased. Since it slides on the alloy-based magnetic head, durability is required, and an improvement effect can be seen in this respect. It has the excellent effect of improving performance and achieving uniform performance.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of a magnetic recording medium that can be obtained by the method of the present invention, FIG. 2 is a schematic diagram of the configuration of an apparatus used to carry out the present invention, and FIG. 01...Polymer film, 2...Ferromagnetic metal thin film, 3... Enlarged cross-sectional view of the recording medium.
Vapor deposition layer, 4, 5...Lubricant layer, 6...Roller, 8...Lubricant solution.

Claims (1)

[Claims] A film to be treated with a vapor-deposited film on both sides of the polymer film and a ferromagnetic metal thin film on at least one side is 2mm to 5mm thick.
A method for producing a magnetic recording medium, which comprises maintaining the curvature in a range of mm, immersing it in a lubricant solution, and drying it.