JPS5939805B2 - magnetic recording tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a magnetic recording tape having a magnetic thin film as a magnetic layer, and particularly has improved running properties.

In magnetic recording tapes, in which a magnetic thin film is formed on a plastic film by plating, vacuum deposition, sputtering, etc., the magnetic thin film is harder than the substrate film, compared to ordinary coated tapes in which magnetic powder is coated with a binder. Because it is also brittle, 1. the tape is too stiff and easily lifts off the magnetic head while running; 2. the impact force at the start and stop of running can cause large cracks in the magnetic thin film, causing dropouts. , the three heads had large wear, and other disadvantages.

As a solution to these drawbacks, it has been proposed to generate many fine cracks in the magnetic thin film and fill the gaps with a material with good adhesiveness and slipperiness. The present invention is partially related to this proposal, and particularly aims to improve the running properties of the tape by regulating the direction in which cracks are formed.

That is, in order to improve the above-mentioned defect 1, it is proposed to create anisotropy in the stiffness of the tape (weaken the stiffness in the tape length direction, but leave the stiffness in the tape width direction as it was). . When the tape runs, the position of the tape is not regulated by the guide in the tape width direction, but if the tape is weak, it is likely to bend at the end of the tape when it comes into contact with the guide. Therefore, it is desirable that the tape has strong stiffness in the tape width direction. On the other hand, in the longitudinal direction of the tape, it is desirable that the tape has a weak stiffness from the viewpoint of adhesion to the head. 5 The present invention:
This is proposed based on these reasons, and specifically, it is proposed that the magnetic material layer be made of a magnetic thin film in which there are 100 or more cracks per 1 cm in the tape length direction that extend almost parallel to the tape width direction. The present invention relates to a magnetic recording tape characterized by the following configuration.

To explain the method for manufacturing the tape of the present invention, first, a magnetic thin film is formed on a substrate such as a polyester film or acetate film by plating, vacuum evaporation, sputtering, etc. using a conventional method.

At this time, the thickness of the magnetic thin film in step 5 is set to the final required thickness, or may be made thinner than that. Next, this material is stretched in the length direction of the tape at a low magnification of 0.5 to 5%. At this time, many cracks are formed in the magnetic thin film extending in a direction perpendicular to the stretching direction. Occurrence density of crack “0” (
The number of cracks per unit length in the stretching direction depends on the thickness and mechanical properties of the magnetic thin film, the adhesion state between the magnetic thin film and the base film, the surface shape of the base film, the mechanical properties of the base film, stretching conditions, etc. Varies depending on Magnetic thin film and base pool! When a combination of 5 mm is determined, the crack density changes mainly depending on the thickness of the magnetic thin film and the stretching conditions. In general, as the thickness of the magnetic thin film decreases,
Furthermore, the higher the stretching ratio, the higher the crack density. In order to obtain the crack density required for the tape of the present invention, ie, 100 cracks/cm, by ordinary stretching, the thickness of the magnetic thin film is required to be 0.2 μm or less, preferably 0.1 μm or less. Therefore, if a film thickness greater than this limit is required, it is necessary to generate cracks, form a thin film on top of the cracks, and then stretch the film again to extend the cracks that have formed in the lower layer of the film to the surface. I need to take it. By repeating this process over and over again, it is possible to obtain a crack density of 100 cracks/cm or more even in a relatively thick thin film of 1 to 2 .mu.m. After generating cracks in this manner, a desired magnetic tape can be obtained by forming a thin layer of various synthetic resins, lubricants, antistatic agents, etc. thereon as required. The reason why the crack density is set to 100 cracks/Cm or more is that as a result of experiments conducted by the present inventors, when the crack density is less than 100 cracks/Cm,
It has become clear that image quality and sound quality deteriorate due to enlargement of the total crack gap and irregular enlargement of the crack gap during tape running, especially when repeated rewinding and playback operations. It is something.

Examples of the present invention will be described below along with comparative examples. Example A cobalt magnetic thin film was formed on a polyester film with a thickness of 20 μm by vacuum evaporation, and then the film was passed through parallel metal rolls at different speeds so that the length direction was perpendicular to the roll axis direction at 100°C. After stretching by 2% in the longitudinal direction, it was heat-treated at 160°C.

This series of operations was repeated as necessary to form a magnetic thin film having a desired crack density. Specifically, it was as follows. Sample 1 A crack was generated after forming a magnetic thin film with a thickness of 0.6 μm.

The crack density was approximately 40 cracks/Crrl. Sample 2 After forming a magnetic thin film with a thickness of 0.3 μm, cracks were generated, and then a magnetic thin film with a thickness of 0.3 μm was formed and cracks were generated.

The crack density was approximately 80 cracks/cm. Sample 3 After forming a magnetic thin film with a thickness of 0.1μ, a crack is generated, then a magnetic thin film with a thickness of 0.2μ is formed, a crack is generated, and then a magnetic thin film with a thickness of 0.3μ is formed on top of the crack. A thin film was formed and cracks were generated.

The crack density was about 100 cracks/cm. A dilute solution of stearic acid was applied to the surface of each of these samples to form a thin film of stearic acid (about 0.5 μm in thickness) on the surface, and then slit to a predetermined width to obtain a magnetic tape. As a result of rewinding these tapes using a commercially available video playback device and repeating the playback operation, the tapes obtained from Samples 1 and 2 (comparative example) showed a decrease in image quality within 20 repetitions. However, in the tape obtained from Sample 3 (Example), no deterioration in image quality was observed even after repeated operations 100 times or more.

Comparative Example When preparing Sample 3 in Example, the stretching operation was changed and the metal roll was set and stretched so that the length direction of the film and the roll axis direction were about 45 mm. A tape was made in the same manner as in the example using a sample with a crack of about 45 la.
When this was rewound using a video reproducing device and the reproducing operation was repeated, the tape was bent in the width direction at the guide roll portion at about the 10th time, and the tape became unable to run.

As is clear from the above, the magnetic recording tape of the present invention is of a thin film type and has very good running properties, and therefore has great industrial utility.

Claims (1)

[Claims] 1. A magnetic recording tape characterized in that the magnetic layer is made of a magnetic thin film in which 100 or more cracks extending substantially parallel to the tape width are present per 1 cm in the tape length direction.