JPS6292115A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having a thin ferromagnetic metallic film which excels in magnetic characteristics and scratching resistance by using silicon alone or silicon alloy to form an underlying layer to be interposed between a substrate and the thin ferromagnetic metallic film. CONSTITUTION:This magnetic recording medium is constituted by forming the underlying film layer consisting of the silicon alone or silicon alloy on the substrate and further forming the thin ferromagnetic metallic film layer on the underlying film layer. The underlying film layer consisting of the silicon alone or silicon alloy in contact with the thin ferromagnetic metallic film is formed of the uniform silicon or silicon alloy and therefore, the dense underlying film layer having good smoothness is formed. The thin ferromagnetic metallic film which is uniform and has the excellent smoothness is thereby formed on the underlying film layer, by which the magnetic characteristics are improved and the scratching resistance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferromagnetic metal thin film magnetic recording medium, and more particularly to a ferromagnetic metal thin film magnetic recording medium that has excellent magnetic properties and IN scratch resistance.

[Conventional technology]

In recent years, in response to the increasing density of magnetic recording, polyester,
A ferromagnetic metal thin film type magnet in which a ferromagnetic metal thin film layer made of a ferromagnetic metal, its alloy, or a compound containing these metals is formed by vapor deposition on a base film made of a polymer molded product such as polyimide or polyamide. Recording media are being developed. This type of magnetic recording medium has characteristics that allow for high-density recording compared to conventional coated magnetic recording media in which magnetic powder is dispersed and coated in an organic binder.
The base film made of a polymer molded product has a fine crystalline structure consisting of a crystalline part and an amorphous part, and is essentially non-uniform. The presence of filler particles to adjust smoothness and the adsorption of contaminants make the surface even more uneven, and this unevenness of the base film surface causes deposits to be formed on it by vapor deposition, etc. The ferromagnetic metal thin film layer tends to be non-uniform, which increases the noise.
In addition, the output fluctuation becomes large, making it difficult to obtain a ferromagnetic metal thin film layer with desired magnetic properties in some cases.

Therefore, as a means to overcome these drawbacks, it has been proposed to interpose a single base film layer made of 5io2 under the ferromagnetic metal thin film layer.

[Problem that the invention seeks to solve]

However, although this base film layer has excellent adhesion to the substrate, the surface of the base film layer tends to become rough, making it impossible to obtain sufficiently satisfactory magnetic properties.

[Means for solving problems]

As a result of various studies to solve this problem, the present invention has been devised to improve magnetic properties and abrasion resistance by forming the underlayer between the substrate and the ferromagnetic fully refracting thin film from silicon alone or from a silicon alloy. The present inventors have discovered that a magnetic recording medium having a ferromagnetic metal thin film layer with excellent properties can be obtained, and have completed the present invention.

According to this invention, since the base film layer of simple silicon or silicon alloy in contact with the ferromagnetic metal thin film layer is formed of silicon or silicon alloy with uniform crystal growth, a dense base film layer with good smoothness is formed. Therefore, a uniform ferromagnetic metal thin film layer with excellent smoothness is formed on this base film layer, and the magnetic properties are improved, and the scratch resistance is also improved.

In this invention, the base film layer and the ferromagnetic metal thin film layer are formed on the substrate by means such as vacuum evaporation, ion blasting, sputtering, and plating. A base film made of a commonly used polymer molded material such as polyimide or polyamide is used.

As the material for forming the base film layer, silicon alone or an alloy containing silicon is preferably used, and since these elements have uniform crystal growth, a dense base film layer with good smoothness is formed. Therefore, the ferromagnetic metal thin film layer formed thereon is uniform and has excellent smoothness, and the magnetic properties are improved.

The layer thickness of the base film layer according to the present invention is set to 20 mm in order to exhibit a sufficient base film effect and to prevent minute cracks and thermal deformation of the base film layer due to the difference in thermal expansion coefficient between the substrate and the base film layer.
It is appropriate to have a range of 0 to 2000 people, and 400 to 70 people.
It is more preferable to set the number to 0 people.

The magnetic materials forming the ferromagnetic metal thin film layer include total bending elements such as cobalt, nickel, and iron, as well as alloys or oxidized materials such as cobalt-nickel, cobalt-iron, cobalt-chromium, and cobalt-nickel-chromium. material, and Co-
P, Co-Ni-P, etc. are preferably used.

When using a base film made of a polymer molded product as a substrate, there is some difficulty in adhesion between this base film and a base film layer made of simple silicon or a silicon alloy. Between Ti01Ti2
03, titanium oxide such as TiO2, silver oxide (Ago),
Aluminum Mide (Al□Oa), Sin, SiO, +
It is preferable to interpose an oxide layer such as silicon oxide or bismuth oxide (Bi203), etc. When these oxide layers are interposed, the adhesion between the base film and the base film layer made of simple silicon or silicon alloy is improved. More improved. In particular, when a silicon oxide layer, which is an oxide of the same element as the base film layer made of simple silicon or a silicon alloy, is interposed between the base film layer and the base film, not only adhesive properties but also magnetic properties and #It has much better scratch resistance and is recommended.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 Surface treatment (A
r gas, bombardment treatment), this is loaded into a vacuum evaporation device, and the first evaporated material shown in Table 1 below is evaporated under the respective conditions to form a first base film layer. The second evaporated material shown in the table is evaporated under the respective conditions.
A base film layer was formed.

Table 1 Next, under a residual gas pressure of 5 x 10-') oxygen pressure on the base film on which the base film layer of this two-layer structure was formed,
A ferromagnetic metal thin film layer was formed by depositing cobalt metal to a thickness of 2000 nm. For cobalt metal vapor deposition, continuous oblique incidence vapor deposition is performed by installing a deposition prevention plate in the vapor deposition equipment so that the angle between the incident direction of the cobalt metal vapor and the normal direction of the Haas film (incident angle) is 45°C or more. Ta.

Next, cut this into a specified width and attach magnetic tape.
It was.

Example 2 Implementation 1? In IJ 1, the first evaporation material was omitted to form a single base film layer, and the second evaporation material, Si, was deposited to a film thickness of 500 nm to form a single layer of Si evaporated base film layer. A magnetic tape was produced in the same manner as in Example 1 except for the formation.

Comparative Example 1 In place of the Si vapor deposit base film layer in Example 2, SiO□
A magnetic tape was produced in the same manner as in Example 2 except that the underlayer was formed.

The coercive force (Hc) and square shape (Br/8m) of the magnetic tapes obtained in each Example and each Comparative Example were measured, and the adhesive strength and scratch resistance were tested.

Adhesion strength was determined by cellotape i7.111iSlt test and diamond drawing test, and scratch resistance was determined by scratching with a degreased surface.

Table 2 below shows the results.

Table 2 C Effects of the Invention] As is clear from Table 2 above, the magnetic tapes (Examples 1 and 2) obtained by the present invention had a 5in2 lower t
Magnetic tape obtained by forming tt+ film layer (Comparative Example 1)
It can be seen that both have a large coercive force and excellent magnetic properties. In particular, SiO2-81 shown in Example 1
The magnetic tape consisting of two base film layers exhibits better properties in terms of coercive force and square shape, and also has better adhesion and tM (a) properties than conventional magnetic tapes. It can be seen that it is also excellent against scratches.

Claims (1)

[Claims] 1. A magnetic recording medium characterized in that a base film layer made of simple silicon or a silicon alloy is formed on a substrate, and a ferromagnetic metal thin film layer is further formed on this base film layer.