JPH0432019A - Magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium such as a magnetic tape or a magnetic disk suitable for use in the audio field or the video field.

[Summary of the invention]

In the present invention, a first magnetic layer, which is a coated film of magnetic paint, and a second magnetic layer, which is made of metal magnetic 11IiW4, are sequentially laminated on a non-magnetic support. By interposing an intermediate layer made of a polymeric material between the two layers, an attempt is made to obtain a magnetic recording medium with excellent magnetic properties and electromagnetic conversion properties.

[Conventional technology]

As magnetic recording media such as magnetic tapes and magnetic disks,
A magnetic layer is formed by applying a magnetic paint prepared by mixing and dispersing magnetic powder, which is a fine powder of ferromagnetic material, a resin binder, an organic solvent, various additives, etc., onto a non-magnetic support such as a polyester film. So-called coating-type magnetic recording media are widely used.

Alternatively, with the increasing demand for high-density magnetic recording, magnetic materials made of metals or alloys such as Co-Ni alloys are being made using plating or vacuum thin film formation techniques (vacuum evaporation, sputtering, ion plating, etc.). A so-called vapor deposition type magnetic recording medium has been proposed in which a metal magnetic thin film is directly deposited on a non-magnetic support such as a polyester film.

This vapor-deposited magnetic recording medium has excellent coercive force, squareness ratio, electromagnetic conversion characteristics in short wavelength range, etc., and the thickness of the magnetic layer can be made extremely thin, so there is no thickness loss during recording demagnetization or reproduction. It has many advantages, such as being extremely small, and since the magnetic layer does not contain a non-magnetic material such as a binder, the packing density of the magnetic material can be increased.

Incidentally, in a magnetic recording medium used in, for example, a high-quality video tape recorder, it is required to be able to sufficiently obtain short-wavelength output such as a luminance signal as well as long-wavelength output such as an audio signal.

Therefore, a magnetic layer is formed by applying an acicular magnetic powder such as CO-containing 7 Fezes or an alloy powder (so-called metal powder) of Co, Fe, Ni, etc. together with a binder on a non-magnetic support. Co-Cr type or Co-Ni-0 on top
A technique has been proposed in which a magnetic layer having a two-layer structure is formed by depositing a metal magnetic thin film. According to this technology,
It is possible to obtain a magnetic recording medium that has both long wavelength output from the lower magnetic layer and short wavelength output from the upper metal magnetic thin film.

[Problem to be solved by the invention]

However, in the above method, when forming the upper gold RJ7A magnetic thin film, air or organic residual gas may be generated from the lower magnetic layer, or the binder, additives, etc. contained in this magnetic layer may be released. Since it is heated and gas is generated, it becomes difficult to stably grow the crystals of the upper layer metal magnetic thin film. As a result, although the properties of the lower magnetic layer can be secured to some extent, the properties of the upper metal magnetic thin film tend to be insufficient.

Therefore, the present invention has been proposed in view of the above-mentioned conventional situation, and provides a magnetic recording medium that eliminates the disadvantages of the above-mentioned two-layer structure and has excellent magnetic properties and i-magnetic conversion properties. The purpose is to provide.

[Means to solve the problem]

The inventors of the present invention have conducted extensive research over a long period of time in order to achieve the above-mentioned objective. As a result, the present inventors have discovered that the lower magnetic layer is formed by coating on a non-magnetic support, and the upper magnetic layer is composed of a metal magnetic IL film. By interposing an intermediate layer using a heat-resistant polymer material, metal magnetic l1 can be stably produced without being affected by the lower layer.
The inventors have discovered that it is now possible to grow crystals of II and ensure good output characteristics over a wide wavelength range.

The present invention was completed based on such findings, and includes coating a first magnetic layer mainly composed of magnetic powder and a binder on a non-magnetic support, and forming the first magnetic layer on a non-magnetic support. It is characterized in that an intermediate layer made of a polymeric material is formed on the layer, and a second magnetic layer made of a metal magnetic thin film is further deposited on the intermediate layer.

That is, the magnetic recording medium of the present invention, as shown in FIG.
It consists of a non-magnetic support (1), a first magnetic layer (2), an intermediate layer (3) and a second magnetic layer (4) formed on the non-magnetic support (1).

In the magnetic recording medium of the present invention, the first magnetic layer (2) is formed by applying a magnetic paint made by dispersing and kneading magnetic powder together with a binder and other additives onto the surface of the non-magnetic support (]). formed by. The magnetic material, binder and other additives used in the first magnetic layer (2) include:
Any conventionally known material can be used and is not limited in any way.

Further, the second magnetic layer (4) is formed by depositing a metal magnetic material using a vacuum thin film forming technique. The metal magnetic material used for this second magnetic layer (4) is also a conventionally known ferromagnetic metal material 1 such as Co-Cr, Co-
Ni, Co-Ni-0, C.

-N i -Cr, etc. can be used, and is not limited in any way.

On the other hand, these first magnetic layer (2) and second magnetic layer (4)
The intermediate layer (3) interposed therein is made of a polymeric material, preferably a heat-resistant polymeric material, and when forming the second magnetic layer (4), the intermediate layer (3) is This is provided to prevent the adverse effects of gases generated from

As the polymer material, polyesters such as polyethylene terephthalate, plastics such as polyimide, polyamide, polyurethane, nitrocellulose, etc. can be used. However, vinyl chloride or the like cannot be used because it generates chlorine-based gas when heated.

The thickness of this intermediate layer (3) is preferably about 0.05 to 1 μm. If the film thickness is too thick, the first magnetic layer (2
) and the second magnetic layer (4) are magnetically separated, making it particularly difficult to ensure sufficient characteristics of the first magnetic layer (2), which is the lower layer. On the other hand, if the intermediate layer (3) is too thin, sufficient effects cannot be obtained.

The intermediate layer (3) is formed on the first magnetic layer (2).

Methods for forming this intermediate layer (3) include a solution method in which the polymer material is dissolved in an appropriate organic solvent and applied, a melting method in which a molten polymer material is applied, and a vacuum method using vapor deposition or sputtering. can be mentioned.

The material for the non-magnetic support (1) used in the magnetic recording medium of the present invention may be any material used in ordinary magnetic recording media, and its forms include film, tape, and sheet disk. .

It may be a card, a drum, etc.

[Effect]

In the magnetic recording medium of the present invention, since the intermediate layer is formed between the first magnetic layer and the second magnetic layer formed on the non-magnetic support, when forming the second magnetic layer, In addition, gas generation from the underlying first magnetic layer is prevented by the intermediate layer. As a result, the crystal growth of the second magnetic layer is performed stably, and the original magnetic properties of the second magnetic layer are ensured.

〔Example〕

The present invention will be explained below based on specific experimental results, but it goes without saying that the present invention is not limited to these Examples.

A first magnetic layer was formed by applying a magnetic paint prepared using 1 m metal magnetic powder to a thickness of about 4 μm on a non-magnetic support. Then, polyethylene terephthalate was dissolved in a suitable organic solvent, and this solution was applied onto the magnetic layer to form an intermediate layer having a dry thickness of 0.2 μm. Furthermore, CO
e, e. A second magnetic layer having a thickness of 0.2 μm was formed on the intermediate layer by sputtering using Ni, 4° alloy as a target, thereby producing a magnetic tape.

mλ A magnetic tape was prepared in the same manner as in Example 1 except that the polyethylene terephthalate used in Example 1 was replaced with polyurethane to form an intermediate layer having a thickness of 0.5 μm.

This tim Example 1. A sample tape was produced in the same manner as in Example 1 except that the intermediate layer as in Example 2 was not formed.

The electromagnetic conversion characteristics of each magnetic tape produced as described above were investigated. The results are shown in Table 1.

The electromagnetic conversion characteristics are values obtained by measuring the reproduction output of each magnetic tape when a signal is recorded at a wavelength of 0.5 μm. Further, Table 1 shows relative values when the reproduction output of the magnetic tape of Comparative Example 1 is set to OdB.

From Table 1, it was found that the itM1 conversion characteristics were improved by interposing the intermediate layer between the first magnetic layer and the second magnetic layer. The reason for this is that when forming the second magnetic layer, the intermediate layer prevents the generation of gas from the first magnetic layer, which is the underlying layer, so that the crystal growth of the second magnetic layer can be performed stably. This is thought to be because the original characteristics of the second magnetic layer can be maintained.

(3) Intermediate layer [Effect of the invention] As is clear from the above explanation, in the magnetic recording medium of the present invention, an intermediate layer is interposed between the first magnetic layer and the second magnetic layer. This makes it possible to prevent the adverse effects of the gas ordered from the first magnetic layer when forming the second magnetic layer.

Therefore, the original characteristics of the second magnetic layer can be secured, and the long wavelength output of the first magnetic layer and the short wavelength output of the second magnetic layer can be secured, and magnetic recording with excellent magnetic conversion characteristics can be achieved. media can be provided.

(4)・ ・Second magnetic layer

Claims (1)

[Claims] A first film mainly consisting of magnetic powder and a binder is placed on a non-magnetic support.
a magnetic layer is formed by coating, an intermediate layer made of a polymeric material is formed on the first magnetic layer, and a second magnetic layer made of a metal magnetic thin film is further deposited on the intermediate layer. A magnetic recording medium characterized by: