JPS6173228A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease the signal drop-out rate in high-density magnetic recording by forming a thin ferromagnetic metallic film as a magnetic recording layer and maintaining the coefft. of dynamic friction in the tape side face part at a specific value or below. CONSTITUTION:The magnetic recording medium is constituted of a high-polymer substrate 1, a primer coating layer 2, a thin ferromagnetic metallic film 3, a lubricant layer 4 and a back coat layer 5. Polyester, polyolefin, cellulose, deriv., polyamide, etc. into which the pulverous particles such as MgF2, CaF2 and CaCO3 are incorporated to improve the coefft. of dynamic friction are used for the substrate 1. The layer 2 may be the resin alone or the resin layer contg. a filler. If the coefft. of dynamic friction is <=0.35, there is no increase in signal drop-out and large frictional force is not generated and therefore the traveling of the tape is extremely stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium suitable for high-density magnetic recording.

Conventional structure and its problems As recording density increases with short wavelength recording and narrow track recording, the effects of signal dropout become more serious, and in recent years ferromagnetic metal thin films, which are essentially suitable for heavy density recording, have been Since it is effective to increase the signal output by using the magnetic recording layer as a magnetic recording layer, development is active in various fields.

These magnetic recording media are generally made by forming a ferromagnetic metal thin film on a polymer film such as polyester or polyimide using electron beam evaporation or high frequency sputtering, and then disposing a lubricant layer on the top surface. When used as a tape-like recording medium, the error rate may increase when the track length becomes less than 10 μm even if a tracking method is used. Improvements are needed to increase the limits of recording.

OBJECTS OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic recording medium that has improved reliability against signal dropout phenomena and is capable of high-density magnetic recording.

Structure of the Invention The magnetic recording medium of the present invention is tape-shaped, and has a magnetic recording layer made of a ferromagnetic metal thin film characterized by a dynamic friction coefficient of 0.35 or less on the side surfaces of the tape, and has a magnetic recording layer that can withstand repeated use. Highly reliable magnetic recording without increasing the signal dropout phenomenon can be realized.

Description of examples The present invention will be described below with reference to the drawings.

Both FIG. 1 and FIG. 2 are enlarged sectional views of the magnetic recording medium of the present invention.

In FIG. 1, 1 is a polymer substrate, 2 is an undercoat layer, 3 is a ferromagnetic metal thin film layer, 4 is a lubricant layer, and 5 is a back coat layer.

In FIG. 2, 1.2 and 4.5 are considered to be common elements with those in FIG. 1, and are indicated by the same numbers. 6 is a soft magnetic layer, and 7 is a perpendicular magnetic film layer.

The polymer substrate used in the present invention is polyester, polyolefin, cellulose derivative, polyamide, polyamideimide, polyimide, etc., and in order to meet the requirements of the present invention, fine particles such as "JF2 + CaF2 + QaCO3" are forcibly mixed. It must have an improved coefficient of dynamic friction.

Due to this configuration, the average surface roughness tends to be extremely rough, and this tendency leads to surface loss in high-density magnetic recording, which is disadvantageous, so it is preferable to provide two subbing layers. The undercoat layer 2 may be a resin layer containing only a resin or a filler, and sometimes may be a vapor deposited layer of Ti, Mu1, or the like.

Other elements used in the present invention may be within the known range.

In addition, improvement in the coefficient of dynamic friction at the tape end can be achieved by treating the end with a pancake shape, but from the viewpoint of reliability, it is better to satisfy the requirements of the present invention with the cut end exposed. preferable.

The coefficient of dynamic friction was measured by stacking tapes and measuring the friction force during movement between a stainless steel post with a surface of 0.1 S or less, and the environment was 20 ± 5 ° C 160 ° C.
The RH was ±10%.

Under these conditions, if it is 0.35 or less, the critical significance of no increase in signal loss is not clear, but it is a natural friction phenomenon, and if it is 0.36 or less, mass transfer between opposing surfaces is If it is less than 0.35, no large frictional force will be generated, so the running of the tape will be extremely stable. Improvements were being made, but the recording density was extremely high, and the area of one signal was 0 crf.
When the friction on the sides of the tape is high,
Although the area of this part is small, it has a large impact on driving, and it is thought that it will eliminate the negative effects such as signal failures and costs.

A more specific example will be described below.

(Example) Polyethylene terephthalate with a thickness of 7 μm to 12 μm was prepared. A filler was added to the polyethylene terephthalate to lower the coefficient of friction. Using this film, a Go-Ni-0-based obliquely evaporated film was formed by electron beam evaporation.

On a film moving along a cylindrical can with a diameter of 1 m,
Vapor deposited in oxygen at 1X10 Torr with a minimum incident angle of 15 degrees, thickness 0-16 CtimJ, coercive force 1000 [Oe]
, the entire magnetic recording layer with a saturation magnetic flux density of 6300 (Gauss) was formed. The lubricant used was stearic acid applied to a dry thickness of 100 people and dried.

Each was slit into a width of 8f1, made into a tape, and the dynamic friction coefficient μk of the side surface was measured, and the signal was 0.66 μm.
Missing defects were measured using a recording wavelength of 9 μm and a track width of 9 μm. If the signal output was 10 dB or more lower during reproduction, it was considered to be missing.

The medium conditions and the properties obtained are summarized in Table 1.

(Left below) As is clear from the table above, the product of the present invention also has a low signal loss rate.
Moreover, it can maintain its performance stably even after repeated use, and can greatly improve reliability in high-density recording, making it extremely promising for the future trend of digitalization.

Effects of the Invention As described above, the magnetic recording medium of the present invention has a magnetic recording layer of a ferromagnetic metal thin film, and a dynamic friction coefficient of 0.3 for the tape side surface.
By setting the value to 5 or less, the signal dropout problem in high-density magnetic recording is greatly improved, and its practical effects are significant.

[Brief explanation of the drawing]

Both FIGS. 1 and 2 are enlarged sectional views of the magnetic recording medium of the present invention. 1... Polymer film, 3, 7... Magnetic recording layer.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer and having a dynamic friction coefficient of 0.35 or less at the tape side surface.