JPS5922225A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To enable the easy manufacture of a magnetic recording medium having virtually no curls by subjecting a substrate to heat shrinkage in the stage of vapor deposition thereby decreasing the curls and decreasing (lo-l)/lo to <=4%. CONSTITUTION:A vertically magnetized Co-Cr film having the axis of easy magnetization in the direction perpendicular to the film plane is formed on a film consisting of a heat resistant polymer material via a Ti film. The thickness of the Ti film in this case is 800Angstrom , the thickness of the Co-Cr film 2,000Angstrom and the thickness of the polymer film 12mum. The temp. on the circumferential side face of a can is 190 deg.C and the thermal shrinkage of the polymer film after left standing for 10min is 0.6%. The resulted magnetic recording medium is positively curled and the (lo-l)/lo thereof is 2%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetic magnetic layer in which a magnetic layer mainly composed of CO and Or is formed on a substrate made of a polymer material via a Ti film, a Per70 film, a T1 film, and a Permalloy film. This article relates to a recording medium and its manufacturing method, and its purpose is to prevent the occurrence of curls that adversely affect the running properties, winding properties, magnetic head touch, etc. of magnetic recording media.
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Conventionally, as magnetic recording media, coated media in which magnetic powder is coated on a non-magnetic substrate have been used.

Currently, there is a trend toward smaller size and higher density of magnetic recording/reproducing devices, but there is a limit to the higher density of coated media. Thin film media made of ferromagnetic metal thin films are attracting attention as a media that exceeds this limit.

As a thin film material, the one containing ■ as the main component is C.

It is the most excellent because it has a large magnetocrystalline anisotropy energy due to the hcp structure. In particular, a Go-Or film containing 10 to 30% of Or by weight can be a perpendicular magnetization film with excellent short wavelength recording and reproducing characteristics. A Co-Or film containing 10 to 30 parts by weight of Or has excellent corrosion resistance.

That is, a magnetic recording medium whose magnetic layer is an -Or film containing 10 to 30% of Or by weight can be said to be an ideal thin film medium because it is practical and has very excellent short wavelength recording and reproducing properties. Methods for producing thin film media made of ferromagnetic metal thin films include plating, sputtering, and vacuum evaporation, but vacuum evaporation is the most superior in terms of mass production and stability. In order to form a thin film medium with high productivity and stability using the vacuum evaporation method, as shown in FIG. What is necessary is to perform the vapor deposition while

Note that 3 and 4 are a supply roll and a take-up roll for the substrate 1, respectively, and 5 is an evaporation source.

However, when a thin film is formed by the above method, it generally curls so that the ferromagnetic metal thin film 6 shown in FIG. 2 is on the inside or outside. This causes a problem such as poor head touch. Hereinafter, the states shown in FIGS. 2(a) and 2(b) will be referred to as normal curl and reverse curl, respectively. For use as a magnetic recording medium, C6o g) / , e
It is necessary that o be 4 or less. However, e is the length in the curled state as shown in Figure 2,
10 is the length without curls. In order to satisfy the above conditions, either a non-magnetic layer is formed on the opposite side of the ferromagnetic metal thin film 6 in the magnetic recording medium as shown in FIG. It would be possible to shrink the substrate 1 by performing a treatment, but in any case, at least one additional step is required.

The method of the present invention reduces curl in a magnetic recording medium whose magnetic layer is a film mainly composed of [Ar] and Or by thermally shrinking the substrate during vapor deposition without increasing the number of steps. It is possible to make (lo-e)/llo less than 4. Note that the present invention has a film thickness of 6 to 1
A film with a thickness of 300 to 3
Although this is limited to the case where a Go-Or film is formed via a 000A Ti film, a permalloy film, or a T1 film and a permalloy film, such a substrate is selected as the substrate on which the Ch-Or film is formed. The reason lies in the following three points. First, the reason for selecting a substrate made of a polymeric material with a film thickness of 6 to 18 μm is that when the magnetic recording medium obtained by the method of the present invention is used as a magnetic tape, a substrate with a film thickness in the range of 6 to 18 μm is optimal. It's no good. That is, the film thickness is 6μ
Polymer substrates with less than m have too little stiffness,
It is difficult to stabilize tape running. Also, if the film thickness exceeds 18 μm, the stiffness will be too high.
Even if there is no curl, the head touch becomes poor. Next, the reason why it is better to insert a Ti film with a thickness of 300 to 3000 A between the polymer substrate and the -Or film is as follows.
This is because such a structure improves the magnetic properties of the [Ar]-Or film. Finally, 300~3QOO
The reason why it is better to insert the permalloy film in A or between the permalloy film and the Ti film is that if the -Or film is a perpendicularly magnetized film, by creating this structure, as is well known, the signal The recording and reproducing characteristics of the device are greatly improved. In addition, in the above, the film thickness is set to 3000A or less because an intermediate layer with a film thickness exceeding 3000A is formed,
Furthermore, if a Go-1r film is formed on top of the Go-1r film, the thickness of the metal thin film becomes too thick, resulting in poor running properties and cracks in the magnetic layer when used as a tape.

Generally, substrates made of polymeric materials undergo thermal contraction when heated, but the present invention heats the substrate by increasing the temperature of the can, and also increases the temperature of the substrate at the time of attachment of evaporated atoms. The material is heat-shrinked so that the amount of shrinkage is such that curl (eo -1,)/lo is a factor of 4 or less. As a result of experiments, deposition was carried out by setting the temperature of the circumferential side of the can to a temperature 100 degrees Celsius lower than the temperature at which the thermal shrinkage rate after leaving the substrate made of polymeric material for 10 minutes was 0.1 to 5 factors. It has become clear that when this is done, (6o-β)/lo becomes 4 or less. This heat shrinkage rate is 0.1
If the temperature of the circumferential side of the can is set to a temperature that is smaller than the
As shown in Figure (a) (7), it has a positive curl, (lo l
)/(l.

became more than 4%. Furthermore, if the temperature of the circumferential surface of the can is set to a temperature at which the thermal contraction rate is greater than 6 cm, the resulting magnetic recording medium will have the magnetic thin film 6 on the outside as shown in FIG. 2(b). It has reverse curls that look like this,
(no 11) /lo was 4% or more. FIG. 4 illustrates the above.

The vertical axis is C1o-(1)/go, and when it is positive, it is a positive curl, and when it is negative, it is a reverse curl. The horizontal axis represents the temperature of the circumferential side of the can as the thermal contraction rate of the polymer substrate. This result was almost independent of the thickness of the substrate and the thickness of the intermediate layer.

Next, examples of the present invention will be described.

Example 1 A Co-Cr perpendicularly magnetized film having an axis of easy magnetization in the direction perpendicular to the film surface was formed on a film made of a heat-resistant polymer material via a T1 film using the vacuum evaporation apparatus shown in Fig. 6. did. However, the thickness of the Ti film is 800A,G.

-The thickness of the Cr film is 200OAI The thickness of the film is 1
It is 2 μm. Also, the temperature of the circumferential side of the can is 190°C.
The heat shrinkage rate of the film after being left at 290°C for 10 minutes is 0°6. The magnetic recording medium has a positive curl, and its (lo l)/e.

was 2%.

Example 2 A Go--Cr perpendicularly magnetized film was formed on a film made of a heat-resistant polymer material via a Ti film and a permalloy film using the vacuum evaporation apparatus shown in FIG. The structure of this medium is the sixth
As shown in the figure. In the figure, 9 is a film made of a heat-resistant polymer material, 10 is a Ti film, 11 is a permalloy film, and 1 is a film made of a heat-resistant polymer material.
2 is a perpendicular magnetization film of -Or. The thickness of the Ti film, permalloy film, and Go-Cr film is 1.
It is 4 μm. The temperature of the peripheral side of the can is 230°C, and the heat shrinkage rate of the film after being left at 330'C for 10 minutes is 1.6. The obtained magnetic recording medium has a reverse curl, and its (, lo -6) /go is 0.
It was 7%.

In addition, in Examples 1 and 2, the curl of the substrate before forming the [with]-Or film was almost Q.

As described below, according to the method of the present invention, a magnetic recording medium with almost no curl can be easily produced.

[Brief explanation of drawings]

Figure 1 is a diagram showing an outline of the internal configuration of a general vacuum evaporation apparatus, and Figure 2 (a). (b) is a diagram showing a curled state of a magnetic recording medium, FIG. 3 is a perspective view of a magnetic recording medium in which curling is prevented by forming a thin film on the back surface, and FIG.
Figure 6 shows the relationship between the curl amount of the magnetic recording medium and the temperature of the peripheral side of the can expressed by the thermal contraction rate of the polymer substrate.
This figure is a diagram schematically showing the internal structure of a vacuum evaporation apparatus used in an embodiment of the present invention, and FIG. 6 is a sectional view of a magnetic recording medium also manufactured in an embodiment of the present invention. 1... Board, 2... Cylindrical can, 5
...Evaporation source, 6...Ferromagnetic thin film, 7...
...Nonmagnetic layer, 8...Mask, 1o...
...Ti film% 11... Permalloy film, 1
2... Perpendicular magnetization film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (CL) (b) Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) On a substrate with a thickness of θ ~ 18 μm made of a polymer material,
70 to 9% CO through a T1 film or permalloy film with a film thickness of 300 to 30 ooZ, or a T1 film and a permalloy film.
1. A magnetic recording medium 1, characterized in that it is provided with a magnetic layer mainly containing O and Or. (2) While running a 6418 μm thick substrate made of a polymeric material along the circumferential side of the cylindrical can, a Ti film or a permalloy film or a permalloy film with a thickness of 300 to 3000 A is deposited on the substrate by vacuum evaporation. C that forms a Ti film and a permalloy film and further contains 70 to 90% by weight of
When a magnetic layer containing O and Or as main components is formed and the substrate is run along the circumferential side of the can, the thermal shrinkage rate of the substrate after being left for 10 minutes is 0.1 to 0.1. A method of manufacturing a magnetic recording medium, characterized in that the temperature of the circumferential side of the can is set to a temperature 100'c lower than a temperature of 6%.