JPS6038769B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal thin film type magnetic recording medium in which a thin film of ferromagnetic metal is formed on a plastic film. This is due to improved adhesion strength.

In recent years, with the progress and development of magnetic recording media, metal thin film type media have begun to attract attention instead of the conventional coating type.

This is because metal thin film type magnetic recording media, which have a thinner and higher density magnetic layer, are superior in recording density than coated type magnetic recording media. However, care must be taken that the magnetic layer may be scraped off by contact with magnetic heads, rollers, etc. As a countermeasure to this problem, the surface of the substrate is activated by corona discharge treatment or glow discharge treatment before forming the magnetic metal thin film, or an underlayer is provided between the metal magnetic layer and the substrate, but industrially When carried out on a production scale, it was not possible to obtain a bond strength sufficient for practical use. The inventor of the present invention has conducted intensive research into a processing method that can be used on an industrial production scale with the aim of improving the adhesion strength between a magnetic metal thin film and a plastic film.
We have found that if heat treatment is performed under the conditions within the shaded area in the figure, the adhesion strength can be improved to such an extent that there is no practical problem.

And the conditions in the shaded area in Figure 1 are as follows: 22<壬×1pi<32 Vines.

The condition is to satisfy gt + 25 × pi < vine increase t + 3o (where t is the heat treatment time [hours] and T is the heat treatment temperature [K]).

The present invention will be described below with reference to an embodiment of a metal thin film type magnetic recording medium formed by vacuum evaporation, but it can also be applied to thin film techniques such as ion plating, sputtering, and plating.

Example 1 Polyethylene terephthalate (polyester) film with a thickness of 6 mm (Surface roughness: average surface roughness Ra = 0.025
(maximum surface roughness Rm = 0.25 mm) with AI of 0.0
Co-Ni alloy (Nj quantity: 2 sheets t%) was deposited on top of it in an oxygen atmosphere of 5 × 10-5 rr.
Deposited.

Within one hour after this sample was taken out into the atmosphere, it was run while being brought into close contact with the surface of a heated roller, and heat treated under various conditions. Note that the processing temperature indicates the surface temperature of the heat roller, and the processing time is the time during which the sample was in close contact with the heat roller, and was adjusted by the running speed of the film and the distance between the heat roller and the film. Example n A sample deposited in the same manner as in Example 1 was taken out into the atmosphere and rolled so that the hardness reached 80 to 95 degrees (measured with cedar on a Shimadzu rubber hardness meter of 20) within 1 hour. It was re-wound and heat treated for various times in a constant temperature bath set at 4000, 60, and 8000.

In addition, since the curl was strong even after the above heat treatment, the flattening treatment was performed after the above heat treatment. The results of the above examples are shown in the following table.

In addition, the evaluation of adhesion strength was performed as follows.

{1) Scratch test As shown in Figure 2, the ferrite head 2, which is kept horizontally by a balancer, is pressed with a weight 3 against the scratched surface 5' of the sample 5 fixed to the glass plate 4, and the glass plate 4 and Sample 5 was moved and pulled at a rate of 10 Q/min, and the weight of weight 3 required to scrape off the deposited film to the extent that light could be transmitted through visual observation was determined.

[2) Peel off. As shown in Fig. 3, the vapor deposition surface 5' of sample 5 and the metal support 6 were adhered with Aron Alpha (trade name of Toagosei Kagaku Kogyo ■), and the film of sample 5 (
(substrate) side and another support 7 with Scotch grip #46.
93 (trade name of Sumitomo 3M) was pulled at a rate of 2 cm/min to measure the force required to separate the deposited film from the substrate.

[3' Endurance test cassette deck RS-678U (product of the applicant) 2
The degree to which the saturation output (1st generation) after repeating the recording and playback 00 times decreased compared to before driving was determined.

As is clear from the above table, if the heat treatment is performed under the conditions indicated by the shaded area in FIG. 1, a metal thin film type magnetic recording medium having practically sufficient adhesion strength can be obtained.

In other words, under conditions of 40 qC or lower and above straight line A in Figure 1, almost no results can be obtained from heat treatment;
Above oo, the polyester film will undergo thermal deterioration,
Under conditions below straight line B in FIG. 1, problems such as flocking, thermal deterioration, reverse curling due to excessive thermal contraction of the substrate, and wrinkles occur. In addition, when placing the sample in a rolled state in a constant salt bath as in Example 0, if the rolling hardness is soft, horizontal wrinkles will occur, whereas if the rolling hardness is hard, blocking and vertical wrinkles will easily occur, so roll the sample before placing it in the constant temperature bath. The hardness should be adjusted to 80-95 degrees. In addition, when a plastic film with a rough surface is used, high tensile strength can be obtained due to the slipperiness that does not require the heat treatment of the present invention, but high recording density is impaired due to spacing loss. It gets lost.

Therefore, the heat treatment of the present invention is performed on a plastic film (R
It is effective when using (a mi 0.03 french, Rm≦0.3 french). As described above, the present invention makes it possible to obtain a metal thin film type magnetic recording medium having adhesion strength to the extent that it does not pose a problem in practical use, by performing heat treatment at a predetermined temperature and time immediately after forming a magnetic metal thin film. It is possible.

Further, by applying the heat treatment of the present invention, dimensional stability as a magnetic tape can also be ensured, and its industrial efficiency is great.

[Brief explanation of drawings]

Figure 1 is a diagram for determining heat treatment conditions for magnetic recording media, Figure 2 is a front view of an apparatus for performing scratch tests on magnetic recording media, and Figure 3 is an apparatus for performing peel tests. FIG. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. After forming a magnetic metal thin film on a plastic film, the following two equations 22<1/T×10^4<32 3/2logt+25<1/T×10^4<3/2lo
A method for manufacturing a magnetic recording medium, characterized in that heat treatment is performed under conditions that satisfy gt+30 (where t is heat treatment time [hours] and T is heat treatment temperature [°K]). 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the plastic film is a film containing at least a polyester film. 3. The plastic film has a surface roughness that satisfies the following two formulas: Ra≦0.03μ, Rm≦0.3μ (where Ra is the average surface roughness and Rm is the maximum surface roughness). A method for manufacturing a magnetic recording medium according to claim 1, characterized in that: