JPS58121132A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To ensure the uniform magnetic properties over a wide area, by vapor depositing a ferromagnetic layer on a high polymer molded product substrate while moving this substrate along a rotary supporter and then taking up the substrate when the temperature of the substrate is set at a level lower than the glass transition point after cooling the supporter. CONSTITUTION:A high polymer substrate 1 of a polyethylene telephthalate film within a vacuum vapor depositing device is rewound by a shaft 3 and then moved along a rotary supporter 2 having 2m diameter and flowing a refrigerant of 5 deg.C. Then Co and Ni is vapor deposited obliquely on the substrate 1 from an evaporating source 5 via a mask 6. Thus a ferromagnetic layer is formed on the substrate 1. In this case, the supporter 2 is cooled down at 5 deg.C which is lower than the glass transition point 69 deg.C of the film substrate 1. Therefore the substrate 1 is cooled continuously down to a level lower than 69 deg.C until it is separated from a roller 7 at a point D3. As a result, a creep or a distortion due to a local deformation is not produced. Thus the output stability is improved without generation of noises for a magnetic recording medium.

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 has been expected to be a medium suitable for short wavelength recording since the early 1970s, but it took a long time to overcome issues such as durability and corrosion resistance, and in recent years it has not been put into practical use for some audio applications. That's where it was.

Attempts to use vapor-deposited tape for video applications are progressing, but
In terms of obtaining uniform properties in the longitudinal direction and width direction, although a practical level of axiality has been achieved in controlling the magnetic properties,
There are still points to be improved in terms of practical characteristics.

In other words, if you manufacture a large area recording medium in a batch process, make it into a tape, disk, etc., and examine its characteristics,
The two problems are that there are parts with poor output stability at short wavelengths and that the noise is different.

Therefore, in order to find out the cause of this, we thoroughly investigated the magnetic properties.
As a result, it was discovered that the cause was due to the surface properties of the medium, and countermeasures were investigated, leading to 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-mentioned 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 Tq after the vapor deposition is completed and before the substrate leaves the rotating support. can be solved.

The present invention will be explained below using the drawings.

The figure shows the main points of the apparatus for carrying out the present invention. As shown in figure 1, when the substrate 1 is moved along the rotating support 2 from the °C delivery shaft 3 to the winding shaft 4, the evaporation source 6 In the case of oblique deposition, the vapor flow is radiated by the vapor flow, and the incident angle is partially limited by the mask 6 during oblique vapor deposition. 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 the conditions for constant magnetic properties, and also plays the role of reducing the thermal effects of the polymer molded material with a low melting point. .

Here, the axial center of the rotating support 2 is assumed to be O, and the substrate 1
The starting point of vapor deposition at f:D is assumed to be Dl, and the point at which the substrate p1 leaves the rotating support 2 is assumed to be D3. Angle α (/
D OD ) and angle β (/D1oD3) can be arbitrarily selected.
However, since the design concept of maintaining the symmetry of the device is usually dominant, /β is almost never set to more than twice /a.

Although it varies somewhat depending on the manufacturing conditions, when measuring the substrate temperature at point D3, K can be lowered to below Tg by either increasing /β to more than twice /α or increasing the diameter of the rotating support. It was found that it was necessary to satisfy the

At the same time, by lowering the substrate temperature to below Tq, the characteristics can be stabilized, as will be clear from the explanation of Act 6 below.
It was confirmed that the bottleneck in practical application could be eliminated.

That is, the temperature of the roller 7 and the roller (not shown).

The temperature of the W elements in the winding systems such as expanders and rubber rollers increases over time, and when that temperature exceeds Tq, the substrate is locally deformed due to the tension, pressure, etc. received from these winding system elements. Conventionally, this has caused permanent deformation, but the present invention can prevent this.

Next, the present invention will be specifically explained in detail.

[Example 1] A cooling medium at 0°C was circulated through a rotating support having a diameter of 1.4 m, and a temperature of /α-6o0. /β-1200, polyethylene terephthalate film (rg=69'c, thickness 9
．． 61ttn) at an incident angle of 36% in an oxygen atmosphere of 2-5x 10-” Torr.
Electron beam evaporation was carried out at temperatures above 100°C. Vapor deposition thickness is 0.1μm
The moving speed of the substrate is 50 m/min.

The magnetic tape created in this way (tape width is 7 mm)
) The reproduction output fluctuation was investigated over the entire length of 3000 m.

Note that the recording wavelength is 0.65 μm.

As a result, the temperature at the point was 60°C±5°C, and the output fluctuation was 10.3dB, which was excellent.

In comparison, when /β=90°, the temperature of D3 is 7
8'・15℃, 1500/7Z~3000771
The output fluctuation between the two became tadB, and the dropout also increased by 2 to 4 times.

Conversely, /β-220° and the temperature at D3 is 35'
℃, the output fluctuation is the same at ±0.3 dB, and Tq
The following shows that the same effect can be obtained.

[Example 2] A cooling medium of 5°C was poured onto a rotating support with a diameter of 2 m, and a polyethylene terephthalate film (Tq=ea, ts°C,
Similarly, on a substrate having a coating layer with minute protrusions on both sides with a thickness of
o 100% io, electron beam evaporated to a thickness of 13 μm.

Note that the oxygen partial pressure was kept constant at 3-3×10-” Torr.

In this way, the tape was deposited over a length of 3300 tri, and the tape performance was compared under various conditions. Note that the tape width i
d 7 mm, and the recording wavelength is 0,6/J or
And so.

Here, the substrate speed, 1. Condition combination t + of a+ /β
11.

(8) Substrate speed $72zn/min, /α-55°,
/β=1000 (1yol) #
60' no Z/min, /a=66°/β=
900 (q 60m/min/
a = 56° O β 2 600 above (A), (B),
(The substrate temperature at point D3 under each Q condition is 29°±
3℃, 34±3℃, 59-t At 5℃, the output fluctuation is
(±0.34 dB for (to), 32 dB for (to)
, (C) tD case was 0.37 dB, which was good in all cases.

In comparison, when the temperature of the medium is 60°C and the temperature at D3 is 71±2°CK, the output fluctuation is ±3.0° for a tape equivalent to a total length of 960m out of a length of 33oOIη.
adB, the noise increase was 4 dB.

It is clear that the present invention does not limit the coating process in the post-process for completing magnetic tapes and disks.

Regarding the substrate, it does not depend on the type of film such as polyacetate, polyamide polyimide, thickness, surface properties, type of surface coating layer, and conditions, and the type and thickness of the magnetic layer.
Regardless of the type of evaporation method, the evaporation length is 300077.
It was confirmed over a distance of 1 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 large. .

[Brief explanation of the drawing]

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

Claims (1)

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