JPH0827936B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

The present invention relates to a method for producing a magnetic recording medium in which a metal magnetic thin film is formed as a magnetic layer on a non-magnetic support by oblique vapor deposition, and particularly to a surface treatment of the magnetic layer. It is about the method.

[Outline of Invention]

According to the present invention, when polishing a magnetic layer of a magnetic recording medium in which a metal magnetic thin film is formed by oblique vapor deposition on a non-magnetic support, polishing is performed along the growth direction of the columnar structure of the metal magnetic thin film. The present invention aims to reduce the dropout of a ferromagnetic metal thin film type magnetic recording medium and prevent the occurrence of so-called scratches due to surface treatment.

[Conventional technology]

Conventionally, as a magnetic recording medium, γ has been formed on a non-magnetic support.
-Fe ₂ O ₃ , Co containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co containing F
e ₃ O ₄ , γ-Fe ₂ O ₃ and Fe ₃ O ₄ beltride compounds, B-containing compound containing Co, oxide ferromagnetic powder such as CrO ₂ or Fe, Co, Ni as the main component Coating type magnetic produced by coating and drying a magnetic paint in which a powder magnetic material such as alloy magnetic powder is dispersed in an organic binder such as vinyl chloride-vinyl acetate copolymer, polyester resin, polyurethane resin, etc. Recording media are widely used.

On the other hand, with the increasing demand for high-density magnetic recording, a ferromagnetic metal material such as a Co-Ni alloy is coated with polyester by a plating or vacuum thin film forming technique (vacuum deposition method, sputtering method, ion plating method, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a film or a polyimide film, has been proposed and has attracted attention. This ferromagnetic metal thin film type magnetic recording medium is excellent not only in coercive force and squareness ratio but also in electromagnetic conversion characteristics in short wavelength recording, and it is possible to make the thickness of the magnetic layer extremely thin, thereby reducing the recording loss. It has a number of advantages such as extremely small thickness loss during magnetism and reproduction, and higher packing density of magnetic material because it is not necessary to mix an organic binder that is a non-magnetic material in the magnetic layer. .

By the way, when the ferromagnetic metal thin film type magnetic recording medium is manufactured, in order to directly deposit a ferromagnetic metal material such as a Co--Ni alloy as a magnetic layer on a non-magnetic support, the coercive force or the rectangular shape of the magnetic layer is used. In order to improve the magnetic properties such as the ratio, the deposition is generally performed by the oblique vapor deposition method.

[Problems to be solved by the invention]

However, as described above, when the ferromagnetic metal material is left deposited on the non-magnetic support by the oblique deposition method, its surface property is poor and so-called dropout easily occurs, which deteriorates the magnetic characteristics of the magnetic recording medium. Etc. is not preferable. Therefore, it is necessary to improve the surface property of the ferromagnetic metal thin film and reduce the occurrence of dropout.

Therefore, it is an object of the present invention to provide a method of manufacturing a magnetic recording medium capable of reducing the dropout of a ferromagnetic metal thin film type magnetic recording medium and preventing the occurrence of scratches due to surface treatment.

[Means for solving problems]

The present invention has been proposed in order to achieve the above-mentioned object, and after forming a metal magnetic thin film on a non-magnetic support by oblique vapor deposition, the metal magnetic thin film is formed along the growth direction of its columnar structure. It is characterized by polishing in the normal direction.

[Action]

Since the polishing treatment is performed along the growth direction of the columnar structure of the metal magnetic thin film, the surface treatment of the ferromagnetic metal thin film type magnetic recording medium can be performed satisfactorily without stroking the columnar structure, and the occurrence of scratches is prevented. Also, dropout is reduced favorably.

〔Example〕

An embodiment of a method of manufacturing a magnetic recording medium to which the present invention is applied will be described below with reference to the drawings.

The magnetic recording medium to which the present invention is applied is a ferromagnetic metal thin film type magnetic recording medium, particularly a magnetic recording medium on which a ferromagnetic metal thin film is formed by oblique deposition.

Therefore, as shown in FIG. 1, in order to manufacture a magnetic recording medium, first of all, Co-- is applied to the surface of the non-magnetic support (1).
Vacuum-deposit a ferromagnetic metal material such as Ni alloy from an oblique direction,
A magnetic layer (2) made of a ferromagnetic metal thin film is formed.

Here, as the ferromagnetic metal material obliquely deposited, Co-
Other than Ni alloy, Co-Pt alloy, Co-Ni-Pt alloy, Fe-Co alloy, F
e-Ni alloy, Fe-Co-Ni alloy, Fe-Co-B alloy, Co-Ni-Fe
-B alloy or the like can be used, and not limited to this, any ferromagnetic metal material used for this type of medium can be used.

The magnetic layer (2) is formed by the oblique vapor deposition method in order to impart magnetic anisotropy to the ferromagnetic metal thin film and increase the coercive force. Therefore, when the film structure is observed, as schematically shown in FIG. 2, for example, a columnar structure oblique to the right side in the drawing is exhibited.

In the present invention, as a measure for reducing dropout, the magnetic layer (2) is subjected to a polishing treatment using a wrapping tape or the like. However, in a magnetic recording medium in which a ferromagnetic metal thin film is obliquely vapor-deposited, the columnar structure of the ferromagnetic metal thin film forming the magnetic layer has directionality. If it is done, not only the dropout cannot be reduced, but also problems such as scratches on the surface of the magnetic layer occur.

Therefore, the inventors of the present invention, in a magnetic recording medium having a ferromagnetic metal thin film deposited by the oblique vapor deposition method as described above, a method of surface treatment for preventing dropout of the magnetic recording medium, particularly a lapping tape. Various studies were made on the traveling direction of the.

As a result, since the columnar structure of the ferromagnetic metal thin film deposited and formed by the oblique deposition method is formed obliquely with a certain predetermined angle with respect to the non-magnetic support (1), Forward direction with respect to the structure (direction of arrow A in FIG. 2,
Hereinafter, it is referred to as the A direction. It was found necessary to run a wrapping tape on). As described above, when the lapping tape is run in the A direction with respect to the columnar crystals of the ferromagnetic metal thin film, the dropout can be remarkably reduced, and further, the magnetic layer (2) is not damaged. Predetermined surface treatment can be performed without generation.

On the other hand, when the lapping tape is run in the reverse direction (the arrow B direction in FIG. 2, hereinafter referred to as B direction) with respect to the columnar structure of the ferromagnetic metal thin film during the polishing treatment, Not only did the dropout decrease, but scratches were generated on the magnetic layer (2).

That is, using a scratch tape, the magnetic layer (2)
In order to carry out the surface polishing treatment, the lapping tape does not have the effect of polishing treatment and the dropout cannot be reduced unless the lapping tape is run in the A direction (forward direction) with respect to the columnar structure of the ferromagnetic metal thin film. .

Based on the above-mentioned findings, the surface treatment with the lapping tape was actually performed using the ferromagnetic metal thin film type magnetic recording medium.

First, a magnetic alloy of Co ₈₀ Ni ₂₀ (the numerical values indicate the composition ratio of each component in atomic%) is deposited on a 12 μm-thick polyethylene terephthalate base film by oblique vapor deposition from 1500 to 500 The magnetic layer was formed with a thickness of 1600Å.

A wrapping tape was run in the direction A in FIG. 2 on the magnetic recording medium to perform surface treatment of the magnetic layer.

As a result, scratches and the like did not occur on the surface of the magnetic layer, and dropout was significantly reduced.
Good surface treatment was performed.

On the other hand, when the magnetic recording medium prepared in the same manner was used to run the lapping tape in the direction B in FIG. 2 to perform the surface treatment of the magnetic layer, many scratches were generated on the surface of the magnetic layer. There was no reduction in dropouts.

The surface treatment with the wrapping tape can also be applied to a magnetic recording medium having a back coat layer (3) on the back surface of the non-magnetic support (1) as shown in FIG. In the magnetic recording medium having such a back coat layer (3), after the magnetic layer (2) is polished, it is wound up once, so that the magnetic layer (2) and the back coat layer (3) are Will be in direct contact. In this case, even if only the magnetic layer (2) is surface-treated, it may be adversely affected by coming into contact with the back coat layer (3) which is not surface-treated at all. Therefore, it is necessary to polish both the magnetic layer (2) and the back coat layer (3). In that case, the back coat layer (3) is first subjected to a polishing treatment, and then the magnetic layer (2) is subjected to a polishing treatment. By processing in this way,
Since it comes into contact with the back coat layer (3) that has already been surface-treated, it is possible to prevent adverse effects caused by coming into contact with the untreated back coat layer (3). Further, by performing surface treatment on both the magnetic layer (2) and the back coat layer (3), the number of times the lapping tape runs on the magnetic layer (2) is reduced as compared with the case where only the magnetic layer (2) is surface treated. It is possible to prevent the adverse effect on the ferromagnetic metal thin film. Further, the surface treatment can be easily performed.

As is apparent from the above-described examples, when the surface treatment of the magnetic layer is performed by the lapping tape, the lapping tape is run in the direction A (that is, the forward direction) in FIG. 2 with respect to the columnar crystals of the ferromagnetic metal thin film. By doing so, dropout can be reduced and the occurrence of scratches can be prevented.

〔The invention's effect〕

When a magnetic layer of a magnetic recording medium formed by obliquely vapor-depositing a metal magnetic thin film on a non-magnetic support is subjected to polishing treatment for improving magnetic properties such as coercive force and squareness, the columnar structure of the metal magnetic thin film is By causing the lapping tape to run along the growth direction and performing the polishing treatment, it is possible to reduce the dropout of the magnetic recording medium and prevent the occurrence of scratches.

By surface-treating the magnetic layer in this manner, the dropout of the ferromagnetic metal thin film type magnetic recording medium is reduced,
It is possible to provide a method for producing a magnetic recording medium capable of preventing the occurrence of scratches.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing one structural example of a magnetic recording medium surface-treated by the method of the present invention. FIG. 2 is a schematic diagram schematically showing the columnar structure of the ferromagnetic metal thin film of the magnetic recording medium shown in FIG. FIG. 3 is an enlarged sectional view of an essential part showing another example of the structure of a magnetic recording medium which is surface-treated by the method of the present invention. 1 ... Non-magnetic support 2 ... Magnetic layer 3 ... Back coat layer

Claims (1)

[Claims] 1. A magnetic recording medium, comprising: forming a metal magnetic thin film on a non-magnetic support by oblique vapor deposition; and polishing the metal magnetic thin film in a normal direction along the growth direction of its columnar structure. Manufacturing method.