JPH0334610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium such as a vapor-deposited tape in which a metal ferromagnetic layer is disposed as a magnetic recording layer on a polymer molded substrate, and the present invention relates to a method for producing a magnetic recording medium such as a vapor-deposited tape, which has uniform characteristics over a large area. The purpose of the present invention is to provide a method for producing a medium that can be used in a variety of ways.

Vapor-deposited tape is a suitable medium for short wavelength recording
Although expectations have been high since the early 1970s, it took a lot of time to overcome issues such as durability and corrosion resistance.
In recent years, it has been put into practical use in some audio applications.

Attempts to use vapor-deposited tape for video applications are progressing, but although a practical level of accuracy has been achieved in controlling magnetic properties in order to obtain uniform properties in the longitudinal and width directions, There are still points to be improved.

In other words, if you manufacture large-area recording media in batches and examine their characteristics as tapes, disks, etc., you will find that there are parts with poor output stability at short wavelengths and differences in noise. be.

Therefore, in order to find out the cause of this, we investigated the magnetic properties in detail, and as a result, we found that the cause was due to the surface properties of the medium.We investigated countermeasures for this problem and arrived at the present invention.

That is, during vapor deposition, the polymer molded substrate is exposed to high temperature for a short time. Insufficient cooling at this time is associated with the creep phenomenon peculiar to polymer molded products and local deformation caused by the tension and pressure applied during winding.

Therefore, the above problem can be solved by performing vapor deposition while moving the substrate along the rotating support, and cooling the substrate to below its glass transition point Tg before the substrate leaves the rotating support after the vapor deposition is completed. It is possible.

The present invention will be explained below using the drawings. The figure shows the main parts of an apparatus for carrying out the invention. As shown in the figure, when the substrate 1 moves along the rotary support 2 from the delivery shaft 3 to the take-up shaft 4, the vapor flow emitted from the evaporation source 5 causes the mask 6 to be removed in the case of oblique evaporation. With some angle of incidence limited by
Deposited. In manufacturing media for perpendicular recording, the mask is different, but everything else is the same.

The rotating support 2 circulates a medium inside to keep the surface temperature constant, creating conditions for making the magnetic properties constant, and also plays the role of reducing the thermal effects of the low melting point polymer molding. .

Here, schematically, the axial center of the rotating support 2 is O, the starting point of vapor deposition on the substrate 1 is D ₀ , the end point is D ₁ , and the point where the substrate 1 leaves the rotating support 2 is D ₃ . Although a (∠D ₀ OD ₁ ) and angle β (∠D ₁ OD ₃ ) can be chosen arbitrarily, ∠β is usually set to more than twice ∠α because the design concept that maintains the symmetry of the device is dominant. There was very little to be done.

Although it varies somewhat depending on the manufacturing conditions, when measuring the substrate temperature at point D ₃ , in order to make it below Tg, one of the conditions is to make ∠β more than twice ∠α, or to increase the diameter of the rotating support. I realized that I needed to satisfy someone.

At the same time, it was confirmed that by controlling the substrate temperature below Tg, the characteristics could be stabilized and the bottleneck in practical application could be eliminated, as will be clear from the description of the examples below.

That is, the temperature of the roller 7 and the roller (not shown)
The temperature of winding system elements such as expanders and rubber rollers increases over time, and the temperature reaches Tg.
Conventionally, the substrate would be locally deformed due to the tension, pressure, etc. received from the winding system elements, resulting in permanent deformation, but the present invention can prevent this. It becomes.

Next, embodiments of the present invention will be specifically described.

Example 1 A cooling medium at 0°C was circulated through a rotating support with a diameter of 1.4 m, and ∠α = 60° and ∠β = 120°, and was placed on a polyethylene terephthalate film (Tg = 69°C, thickness 9.5 μm). , 80% Co and 20% Ni were deposited by electron beam at an incident angle of 35° or more in an oxygen atmosphere of 2.5×10 ^-5 Torr. The deposition thickness was 0.1 μm, and the substrate movement speed was 50 m/min.

Fluctuations in reproduction output were investigated over a total length of 3000 m of the magnetic tape thus prepared (tape width: 7 mm). Note that the recording wavelength is 0.65 μm.

As a result, the temperature at point _D3 was 50° C.±5° C., and the output fluctuation was ±0.3 dB, which was extremely good.

In comparison, when ∠β = 90°, the temperature of D ₃ is 78° ± 5°C, the output fluctuation is ±3 dB between 1500 m and 3000 m, and the dropout is 2 to 4 dB.
doubled.

Conversely, if ∠β=220°, the temperature at D ₃ is 35°±3
℃, the output fluctuation is the same at ±0.3dB, and Tg
The following shows that the same effect can be obtained.

Example 2 A cooling medium of 5°C was poured into a rotating support with a diameter of 2 m, and a polyethylene terephthalate film (Tg
= 68.5℃, thickness 11.5μm), the incident angle was
100% Co was electron beam evaporated to a thickness of 0.13 μm above 46°.

The oxygen partial pressure was kept constant at 3.3×10 ^-5 Torr.

In this way, it was deposited over a length of 3300m,
We compared tape performance under various conditions. Note that the tape width was 7 mm, and the recording wavelength was 0.6 μm.

Here, condition combinations of substrate speed, ∠α, and ∠β are listed.

(A) Substrate speed 72m/min, ∠α=55°, ∠β=
100° (B) Substrate speed 60m/min, ∠α=55°∠β=90° (C) Substrate speed 60m/min∠α=55°∠β=60° Above (A), (B), (C ) The substrate temperature at point _D3 under each condition is
At 29°±3℃, 34±3℃, and 59±5℃, respectively, the output fluctuation is ±0.34dB for (A) and ±0.3dB for (B).
It was 0.32 dB, and ±0.37 dB for (C), which was good in both cases.

Compared to these, when the temperature of the medium is 60℃, D ₃
When the temperature reached 71 ± 2 degrees Celsius, there was an output fluctuation of ± 3.8 dB and an increase in noise of 4 dB for the tape, which was equivalent to a total length of 950 m out of a length of 3,300 m.

It is clear that the present invention does not limit the coating process in the post-process to complete the magnetic tape or disk.

In addition, regarding the substrate, it does not depend on the type of film such as polyacetate, polyamide polyimide, thickness, surface property, type of surface coating layer, and conditions.
It was confirmed that the results were independent of the type and thickness of the magnetic layer and the type of evaporation method used over a deposition length of 3,000 m to 15,000 m.

As explained above, according to the present invention, it is possible to stably manufacture a magnetic recording medium with uniform characteristics over a wide area, high performance, and suitable for short wavelength recording, and its industrial value is extremely high. big.

[Brief explanation of drawings]

The figure is a diagram showing an example of a main part of a manufacturing apparatus for carrying out the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Rotating support body, 5... Evaporation source, 7... Roller.

Claims (1)

[Claims] 1 After forming a ferromagnetic layer by vapor deposition on a polymer molded substrate that moves along a support, when the temperature of the substrate is below Tg, where the glass transition point of the substrate is Tg. A method for manufacturing a magnetic recording medium, comprising separating the substrate from the support and winding it up.