JPS6045933A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic tape having an excellent recording and reproducing characteristics from a low frequency region to a high frequency region by providing a coating type magnetic layer, a smooth surface resin layer burying the reggedness on the surface thereof and a thin film magnetic layer formed by vapor deposition of a ferromagnetic metal in this order on a base plate of a high polymer. CONSTITUTION:A coating type magnetic layer 11 dispersed with ferromagnetic powder in a binder is formed on a high polymer base plate 10 such as polyethylene terephthalate. A resin layer 12 subjected to a surface smoothing treatment by filling an urethane resin in order to fill the ruggedness on the surface of the layer 11 is formed. An extremely thin ferromagnetic metallic (may be alloy) layer 13 having about 0.1mu thickness is formed by diagonal vapor deposition on the layer 12. Even if the surface of the layer 12 is smooth and the layer 13 is thin, there is the layer 13 which is continuously formed and therefore even if the layer 13 is thin, there is no deficiency in the reproduced output of low frequency - middle frequency. The excellent tape suitable for high fidelity is obtd. by the combination thereof with the characteristics in the high frequency range of the layer 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording medium having a thin film magnetic layer formed thereon.

Conventional configurations and their problems Magnetic recording media used for magnetic recording are required to have a wide variety of characteristics, shapes, and dimensions depending on the purpose and method of use. Among these, the magnetic tape used in tape recorders is made by forming a magnetic layer on a long polymer molded substrate, and then forming a magnetic tape with a predetermined width.
Cut to length and use.

High-density recording has always been sought for magnetic tapes used in tape recorders, as well as magnetic recording devices. This high-density recording is also necessary for tape recorders to record faithfully to the original sound and for high-fidelity playback. In order to meet the general demand for high-density recording, magnetic recording devices require the development of amplifiers and recording/playback heads.

This was addressed through improvements and speaker improvements.

On the other hand, magnetic tape has been improved by improving the magnetic powder that forms the magnetic layer, increasing the magnetic material density, residual magnetic flux density, and squareness ratio in the magnetic layer, and forming a thin magnetic layer on the substrate using ferromagnetic material. I came. Among these, a thin magnetic layer using a ferromagnetic material has a magnetic density of almost 100%, and the magnetic layer can be extremely thin, so it has less demagnetizing field and thickness loss, and can be shortened as shown in curve 1 in Figure 1. A high-density magnetic tape suitable for wavelength recording can be obtained. However, since it is thin, the total number of magnetic fluxes is small, and the lack of output during playback at low and medium frequencies has been a problem as a magnetic tape for tape recorders. In addition, the coated magnetic tape commonly used in the past has low
As shown by curve 2 in FIG. 1, the reproduced output characteristics up to the middle range were good, but the frequency characteristics above 15 KHz were not sufficient. Therefore, a magnetic recording medium in which a thin magnetic layer is formed on a coated magnetic layer has been proposed as a magnetic tape for high-fidelity applications that requires faithful recording and reproduction of original sound over a wide frequency band from low to high frequencies. ing.

FIG. 2 shows a cross-sectional view of a magnetic tape having a multilayer structure in which a thin magnetic layer is formed on such a coating layer.

A coated magnetic layer 4 is formed on a long polymer molded substrate 3, and then a thin film magnetic layer 6 is formed.

FIG. 3 shows typical frequency characteristics of a magnetic tape with a multilayer structure of coated thin films. At an input level of -20 dB, a frequency characteristic shown by a broken line 7, which is almost the same as the curve (solid line) 6 for only the coated magnetic layer, is obtained, and at an input level of 0 dB, the frequency characteristic is compared to the curve for only the coated magnetic layer (solid line 8). A good curve 90 frequency characteristic shown by the broken line can be obtained. However, the frequency characteristics (7, 9) of the multilayered magnetic tape shown in Figure 3 are
As is clear from the comparison with the frequency characteristics of the thin film magnetic layer shown in the figure, there was a drawback in that the characteristics in the high range were not sufficient.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic recording medium having excellent frequency characteristics of both a coated magnetic layer and a thin film magnetic layer.

Structure of the Invention The present invention comprises a molded polymer substrate, a coated magnetic layer on which magnetic powder is fixed with a binder together with a dispersant, a hardening agent, etc., and a concave portion on the surface of the coated magnetic layer. A magnetic recording medium with excellent frequency characteristics that includes a buried resin layer and a thin magnetic layer made of ferromagnetic material formed on the surface of this resin layer by methods such as vacuum evaporation, ion blating, and sputtering. It is.

DESCRIPTION OF EMBODIMENTS The method for manufacturing a magnetic recording medium of the present invention is shown in the flowchart of FIG. 4, and one embodiment will be described below.

As shown in FIG. 6, a coated magnetic layer 11 is formed using co-gamma magnetic powder on a polyethylene terephthalate (PET) substrate 10 having a thickness of 12 .mu.m. Thereafter, urethane resin was filled in the concave portions of the surface of the coated magnetic layer 11, and the surface was smoothed to the extent that the concave portions were filled, thereby creating a thin film forming surface of the resin layer 12.

An extremely thin magnetic layer was then created on the surface using a vacuum evaporation method.

FIG. 6 shows an apparatus used for forming the thin film magnetic layer, and the forming method will be briefly explained. Exhaust device 16.1 inside the vacuum chamber 14
6 to 1o (Torr) or less, and the material container 1
Cobalt and nickel alloy 19 in 8 is melted by electron gun 2o and evaporated in atomic form. The elongated substrate 22 on which the coated magnetic layer is formed is extended from the unwinding shaft 23 and runs in close contact with the outer periphery of the cooling can 24 for vapor deposition, and is moved to the winding shaft 25 [
It is wound up. Free rollers, expanders, etc. (not shown) are used to move the substrate 22.

The thin magnetic layer is formed by so-called oblique evaporation, in which the low-incidence region is blocked by a mask 17 and the evaporated atomic group 210 is formed. Note that a trace amount of oxygen is supplied during the deposition. In this example, a thin film magnetic layer was formed with a substrate line speed of 1 oom/m:n, a thin film magnetic layer thickness of approximately 04 μllL coercive force yoo (os), and a residual magnetic flux density of 10,000 (Gauss).

2 with the coated magnetic layer and thin film magnetic layer obtained by the method described above.
When measuring the electrical resistance after slitting a layered magnetic recording medium to a width of 3.81 Nm, it was found that the electrical resistance of a conventional two-layered magnetic recording medium that did not undergo coated magnetic layer surface smoothing treatment was approximately 1 [KΩ]. ], whereas the electric resistance of the two-layer magnetic recording medium of this example was less than 6oO [Ω]. This is because the surface smoothing treatment of the coated magnetic layer allows a continuous thin film to be formed even if the thin magnetic layer is as thin as 0.1 (μm) or less.

The frequency characteristics of the magnetic recording medium of the present invention thus obtained are shown in FIG. The input level of the magnetic recording medium with only a coated magnetic layer is -20 dB, O (iBK), whereas the frequency characteristics for iBK are curves 6 and 8 shown by solid lines, respectively, the frequency characteristics of the magnetic recording medium of the present invention are shown by broken lines. Like-
20 (iB and OdB), respectively, as curves 261 and 28. That is, in the middle and low ranges, high output can be obtained by the coated magnetic layer, and in the high range, excellent reproducibility can be obtained by the thin film magnetic layer.

Although the above embodiments have been explained using specific materials and numerical values, the present invention is not limited to the above.

Furthermore, in the formation of the thin magnetic layer, a magnetic recording medium with similar characteristics can be obtained by using sputtering or ion blating in addition to vacuum evaporation, and the magnetic powder used for the coated magnetic layer can also be made of γ-Fe 205, metal, etc. The magnetic recording medium of the present invention having a two-layer structure of a coating and a thin film can be obtained using the above method.

Effects of the Invention The present invention provides a resin layer on a coated magnetic layer that fills in the unevenness of the surface.The smoothness of the surface of the resin layer can be easily increased, and the resin layer has a thickness It is possible to form a continuous thin film magnetic layer with a small resistance, and it is possible to obtain both the high output characteristics of a coated magnetic layer in the low and medium ranges and the frequency characteristics of a thin film magnetic layer in the high range. That is, the magnetic recording medium of the present invention has (1) excellent broadband frequency characteristics that exceed the frequency characteristics of conventional magnetic recording media.

(2) The surface smoothing treatment and the formation of the thin magnetic layer are industrially efficient and suitable for mass production.

(3) Due to the mass production effect, costs can be reduced and magnetic recording media with excellent frequency characteristics can be provided at low cost.

It has excellent effects such as:

[Brief explanation of drawings]

Fig. 1 is a frequency characteristic diagram of the coated magnetic layer and thin film magnetic layer alone, Fig. 2 is a cross-sectional view of a conventional two-layer structure magnetic recording medium, and Fig. 3 is a frequency characteristic diagram of the conventional example of Fig. 2. Fig. 4 is a process diagram for manufacturing the magnetic recording medium of the present invention, Fig. 6 is a cross-sectional view of this embodiment, Fig. 6 is a configuration diagram of the manufacturing apparatus, and Fig. 7 is a frequency characteristic diagram of this embodiment. It is. 10...Substrate, 11...Coated magnetic layer, 12...Resin layer, 13...Thin film magnetic layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 5-3 Figure 6 5 71! l

Claims (1)

[Claims] A coated magnetic layer made of magnetic powder provided on a polymer molded substrate, a smooth surface resin layer that fills in the irregularities on the surface of the coated magnetic layer, and a vacuum evaporation method, sputtering method, ion blating method, etc. on the surface of this resin layer. 1. A magnetic recording medium comprising a thin film magnetic layer made of a ferromagnetic material.