JPH0319620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing a magnetic recording medium in which the magnetic recording layer is a ferromagnetic layer deposited on a polymer molded substrate.

In magnetic recording, the value of using a ferromagnetic metal thin film as a magnetic recording layer for short wavelength recording is well known, and such media can also be produced using wet plating and wet plating methods on a laboratory scale.
They have been manufactured using vacuum evaporation methods, sputtering methods, ion plating methods, etc., and some of them have been put into practical use for low-speed audio, and practical use for video applications is on the horizon. Efforts are being made on all fronts.

In general, magnetic recording media often belong to one of several configurations shown in FIGS. 2a to 2d. Note that illustration of the back coat layer is omitted in the figure.

FIG. 2a shows a case where one ferromagnetic layer 23 is provided on the substrate 22, and FIG.
is arranged on a substrate 24 and a ferromagnetic layer 26 is provided thereon; FIG.
8, 30, and ferromagnetic layers 29, 31 are arranged alternately to form a multilayer structure. FIG. In addition, the ferromagnetic layer 26 (or 3
1) Of course, modifications such as disposing a protective layer thereon are also possible.

The object of the present invention is to solve the problems that occur when manufacturing magnetic recording media on an industrial scale as shown in FIGS. 2b, 2c, and d, respectively.

Of course, even in the magnetic recording medium shown in FIG. 2a, a similar problem occurs when the magnetic layer is divided and constructed by repeated vapor deposition, and the surface is actively treated after vapor deposition, so the structure of the medium It is not important to select a material, but whether or not it is a target of the present invention is determined by the manufacturing process adopted.

Note that vapor deposition here refers to a process of forming a thin film in a vacuum, including vacuum vapor deposition, ion plating, and sputtering.

In the present invention, when a protective layer is deposited after forming a ferromagnetic layer on a polymer molded substrate, one type of ferromagnetic layer is deposited in a predetermined manner, for example, by oblique deposition using two or more rotating cans. We have conducted detailed studies on the problem of cracks in the magnetic layer that occur when the process is treated as a continuous process, such as when repeated evaporation is performed until a certain thickness is reached, or when the surface is oxidized after forming a ferromagnetic layer.
This was achieved as a result of improvements.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a vapor deposition apparatus according to the present invention.

Although FIG. 1 shows a case where there are two rotary cans, the concept is the same when there are three or more rotary cans.
Further, although FIG. 1 shows the case where the vacuum chamber 7 is divided into three chambers, it is not limited to this, and it may be further divided for glow treatment, but this is sufficient to explain the basic requirements of the present invention in detail. We are trying to simplify the process.

Now, as shown in FIG. 1, the upper chamber 10 is mainly provided with a winding system, and the vapor deposition chamber is divided into 8 and 9. In this case, an example of a combination of electron beam evaporation and sputtering has been cited, but as mentioned above, the combination is not limited to this. A first can 5 and an evaporation source 2 are arranged to face each other, and a spatter source 4 is arranged to face a second can 6. The rooms 10, 9, 8 are evacuated by independent exhaust systems 13, 11, 12, respectively.

The substrate 1 is rolled up from the feed shaft 14 via the first can 5 and the second can 6 onto the winding shaft 15. 16 is a free roller, and the expander roller is not shown. A roller 17 is provided to absorb variations in circumferential speed between each can, and is connected to the fulcrum 19 by a lever, for example, so as to apply a constant tension to the film. Note that this configuration is just an example, and the rotation shaft of the roller 17 may simply be slid up and down. 3 is a mask for oblique vapor deposition, 20 and 21 are walls, and the gas introduction part is not shown.

Note that the function of the roller 17 will be explained here. When winding is performed using a plurality of cans, there is almost no slippage between the substrate 1 and the cans because of the vacuum. On the other hand, the rotational speed of the rotating can is maintained constant by controlling the electric motor, but controlling the peripheral speed variation to less than 0.2% is necessary, for example, if the dead weight of a rotating can with a diameter of 1 m is 500 mm wide.
1000 kg for those used for transporting film.
I can tell because it's close to. Further, since the cause of circumferential speed fluctuations is also due to mechanical loss, it is not possible to make the circumferential speeds of each can completely the same even if the cans are finished in the same shape. Therefore, for example, the first can 5 and the second can 6
Even if the relationship is made constant, a displacement corresponding to the above-mentioned fluctuation will occur in the film, and when the magnetic layer is subjected to such fluctuation after forming the magnetic layer, cracks will occur in the vapor deposited layer in a part of the long side, and this will occur due to the short wavelength. The roller 17 is a limiting cause of noise during recording and must be prevented.
This can be completely prevented by absorbing .

Next, embodiments of the present invention will be described in more detail.

Example 1 A polyethylene terephthalate film (reinforced stretched type, thickness 12 μm,
Oxygen was introduced from the outside at 0.2/min onto the surface (width 500 mm), and a vapor flow ^of 100% Co obtained by electron beam heating at a vacuum degree of 3 formed a layer. The film thickness is
It was 0.2 μm. Next, N ₂ gas was introduced at 0.1/min, and magnetron sputtering was performed using Si ³ N ₄ as a target at 1×10 ⁻³ Torr to form a protective layer with a thickness of 0.02 μm.

The above steps were carried out in the case where the weight of the roller 17 in FIG. 1 was set to 4 kg and in the conventional method in which the roller 17 was bypassed. The winding speed was 30 m/min, and the fluctuations in the first can 5 and the second can 6 were ±0.15% and ±0.22%, respectively.

The noise was investigated on the magnetic tape produced by heat-treating the substrate on which the ferromagnetic layer and protective layer were formed as described above, applying a resin coating to the back surface of the substrate to impart lubricity, and slitting it into 1/4 inch pieces. .

As a result, the magnetic tape manufactured by the present invention was able to achieve uniform and low noise over a length of 1000 m, whereas the magnetic tape manufactured by the conventional method achieved low noise within a length of 1000 m. There was an area of 180 m where the value was 4 to 6 dB higher.

When we observed that area, we found that cracks had formed in a direction almost perpendicular to the direction of movement of the substrate. Since the occurrence position is not regular, it is necessary to inspect the entire length for practical use, but such an inspection cannot be performed in the actual process, so this tape cannot be used for practical use.

Example 2 Co90% Cr10% was applied 1× on a polyamide film (thickness 8 μm) along a can with a diameter of 500 mm.
A ferromagnetic layer is formed by oblique deposition to a thickness of 0.28 μm at an incident angle of 45° or more in a vacuum of 10 ^-5 Torr, and then a ferromagnetic layer with a diameter of 500 mm is formed.
Surface treatment was carried out using high-frequency glow discharge at an oxygen partial pressure of 0.03 Torr under the following conditions. The film winding speed was 25 m/min, and the peripheral speed fluctuations of the two cans were each ±0.21%. Comparison of noise similar to that in Example 1 over a length of 850 m of magnetic tape manufactured by applying a tension of 25 kg by the roller 17 to absorb circumferential speed fluctuations and by bypassing the roller 17 using the conventional method. I went there.

As a result, for products manufactured using conventional methods, the area with high noise of 8dB to 12dB was a total of 90m long.
Moreover, compared to the 140m high area with 3 to 5 dB, the noise produced by the present invention was uniform and low over the entire length. This did not change even when the weight of the roller 17 was changed from 3 kg to 7 kg.

Example 3 After forming a permalloy layer with a thickness of 1 μm by electron beam evaporation on a polyimide film (thickness 25 μm) along the first rotation can (diameter 500 mm),
A tension of 9 kg was applied with the roller 17, and Co85% Cr15% was deposited to a thickness of 0.33 μm by electron beam evaporation with perpendicular incidence in the second can (diameter 500 mm) to produce a medium for perpendicular recording. did. For comparison, a media was produced in which roller 17 was bypassed.

Film winding speed is 10m/min to 30m/min,
We investigated cases where the circumferential speed fluctuation of each can was ±0.3% and ±0.27%, but it was found that
No cracks were observed over an area of 1300m.

In contrast, those manufactured using conventional methods,
A total of 470 meters of cracks were observed. Even in perpendicular recording, the noise caused by these cracks has the disadvantage of reducing resolution, and the present invention is highly effective.

In addition, polyethylene terephthalate 5.5 μm ~
Using 27 μm thick polyamide films, 3.8 μm to 9.7 μm thick polyamide films, and 25 μm to 190 μm thick polyimide films as substrates, Cr0.2 μm thick films were coated with Co80%Ni20%,
Co70%Ni25%Cr5%, Co95%Pt5%, Co95%W5
% etc. was formed to a thickness of 0.1 μm to 0.3 μm according to the present invention, but similarly no cracks were observed.

In the apparatus shown in FIG.
When moving to the winding shaft 15, Co80%Ni20% is obliquely evaporated at an incident angle of 70° or more in each can (0.05μm thick in each can), and then Co80%Ni20% is deposited at a thickness of 70% in each can. No cracks were observed in the magnetic tape produced by electron beam evaporation at an incident angle of 0.2 μm or more, and a magnetic layer with a total thickness of 0.2 μm was formed on the substrate according to the present invention, and uniform and low noise was achieved. .

The effect of the present invention on preventing cracks caused by displacement of the film caused by sudden changes in circumferential speed was also confirmed in many other examples. Exactly the same effect was confirmed in the case of manufacturing using a device with three cans, two cans with a diameter of 500 mm and one can with a diameter of 1000 mm.

As is clear from the above description, the medium obtained by the present invention is excellent without detracting from the advantages of short wavelength recording, and the present invention has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a manufacturing apparatus according to the present invention, and FIGS. 2a, b, c, and d are sectional views each showing an example of the structure of a magnetic recording medium. 1, 22, 24, 27, 32... board, 2...
Evaporation source, 3...mask, 4... spatter source, 5,
6... Can, 7... Vacuum chamber, 14... Feeding shaft, 15... Winding shaft, 16, 17... Roller, 20, 21... Scratching wall, 23, 25, 26,
29, 31, 33... ferromagnetic layer.

Claims (1)

[Claims] 1. When forming a ferromagnetic layer by vapor deposition on a polymer molded substrate that moves along a plurality of rotation cans whose peripheral speed is controlled at a constant speed by individual motors arranged in series, A method for manufacturing a magnetic recording medium, comprising applying tension to the substrate between adjacent rotating cans. 2. A plurality of rotating rollers whose circumferential speed is controlled at a constant speed are arranged in series to move the polymer molded substrate on which a ferromagnetic layer is to be formed by vapor deposition along the circumferential surface, and the above-mentioned adjacent rollers are arranged in series. An apparatus for manufacturing a magnetic recording medium, comprising means for applying tension to the substrate while it is being moved between rotating cans.