JPH02216618A - Production of 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 "Industrial Application Field" The present invention relates to a method for manufacturing a magnetic recording medium.More specifically, the present invention relates to a method for manufacturing a magnetic recording medium with improved runnability without damaging the kt magnetic metal thin film of the present invention. Regarding the method.

[Prior Art] Generally, magnetic powder is bound together with a binder component onto a substrate made of a plastic film such as polyester, or
Alternatively, a magnetic tape formed by depositing ferromagnetic metals or their alloys on a substrate by vacuum deposition etc.
The friction coefficient when the back side of the tape comes into sliding contact with the guide pin of the deck additional recording system is high, which causes wear and tear, resulting in unstable recording and reproducing characteristics and poor durability.

For this reason, a back coat layer is formed on the substrate surface opposite to the magnetic layer forming surface, which mixes and binds filler (powder), binder (binding agent), or lubricant. Attempts are being made to improve this.

[Problems to be Solved by the Invention] As one of the coating methods for the back coat layer, a gravure coating method as shown in FIG. 3 has been implemented.

However, a problem arose in that the magnetic metal thin film (not shown) on the base film 12 cracked or cracked due to the unevenness of the surface of the gravure roll 10. If the surface of the gravure roll is made smooth, no cracks or breaks will occur in the magnetic metal thin film, but the paint 14 cannot be applied.

Therefore, an object of the present invention is to provide a method for manufacturing a magnetic recording medium that does not cause problems such as cracks or cracks in the magnetic metal thin film due to irregularities on the surface of a gravure roll, which the prior art described above has.

[Means for Solving the Problems] As a means for achieving the above object, in the present invention, a magnetic metal thin i-layer is formed on one surface of a non-magnetic substrate, and the other surface of the non-magnetic substrate is coated by a gravure roll method. When applying paint, the surface irregularities of the gravure roll are (area of the part in contact with the non-magnetic substrate)/(area of the part facing the non-magnetic substrate) ≧0
．． A method of manufacturing a magnetic recording medium is provided, which is characterized in that a gravure roll formed to satisfy the relationship (1) is used.

[Function] As described above, in the method of manufacturing a magnetic recording medium of the present invention,
A gravure roll is used which is shaped so that the ratio of surface irregularities is (area of the part in contact with the non-magnetic substrate)/(area of the part facing the non-magnetic substrate)≧0.1. If this ratio is satisfied, the surface pressure of the gravure roll against the metal thin film is reduced, and the occurrence of defects such as cracks or cracks is suppressed.

If the ratio of the unevenness on the surface of the gravure roll is less than 0°1, cracks or cracks will occur in the magnetic metal thin film.

The higher this ratio is, the better it is for suppressing the occurrence of cracks and cracks.
Since the amount of paint transferred is also reduced, the limit on the ratio is determined by the desired thickness of the paint coating layer applied to the back surface of the non-magnetic substrate.

Gravure roll 1 that can be used in the method of the present invention
An example of the surface is shown in FIG. As shown,
The portion that comes into contact with the non-magnetic substrate, ie, the curved portion 2, is shaped like a base opening. The space between [1] constitutes the open portion 3.

Fig. 2 shows a sectional view taken along the line ■-■. The lower part of the curved portion 2 widens downward. Therefore, the cross section of the curved portion 2 has a substantially trapezoidal shape. If the area of the top surface of the curved part 2 is A, and the area of the top surface of the open part 3 is B, then A/A+8≧0
．． Relationship 1 must be satisfied. As the area of the top surface of the curved portion 2 increases, that is, the value of A increases, the area of the top surface of the open portion 3, that is, the value of B decreases (
Become. Therefore, the value of A/A+H approaches l.

The overall outer shape of the curved portion 2 is not limited to the shape of the base opening as shown in the drawings. If it satisfies the above ratio, it's straight! It can be formed into any shape such as a cane, spiral cane, or dot cane.

The paint that can be applied to the back surface of a nonmagnetic substrate by the method of the present invention is, for example, a paint for forming a back coat layer, a protective film, an anticorrosion layer, a lubricating layer, or the like. Of course, other paints can also be applied.

Although the thickness of the coating layer applied to the back surface of the non-magnetic substrate by the method of the present invention is not an essential characteristic of the present invention, it is within the range of 2,000 to 20,000 layers.

The nonmagnetic substrate used in the magnetic recording medium produced by the method of the present invention is preferably a polymer film such as polyimide, polyester, or polyethylene terephthalate. Therefore, the magnetic recording medium manufactured by the method of the present invention is a magnetic tape, a magnetic disk, etc. cut from a long polymer film nonmagnetic substrate. Magnetic tape is particularly preferred.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

A polyethylene terephthalate film with a thickness of 10 μm was set in a vacuum evaporation apparatus, and a coBONi2o alloy was obliquely evaporated to a thickness of 150'O. A bank coat was applied to the back side of this original fabric using a gravure roll coating device. The surface of the gravure roll used for this Yufu had a base-shaped opening as shown in FIG. As shown in Figure 1,
By keeping the dimension 100μm constant and changing the =J method a, the ratio of A/A+B shown in Figure 2 can be changed to 0.1゜0.
．． 2 and 0.3, and the CoNi magnetic metal thin film layer was examined for cracks and cracks.

A magnetic recording medium was produced as described in the above example except that the ratio ff1 A/A+B was 0.01 and 0.05, and the CoNi&II metal thin film layer was inspected for cracks and cracks. .

The test results for Examples 1 to 3 and Comparative Examples 1 to 2 are shown in Table 1 below.

By using a gravure roll shaped to satisfy conditions (1) and (1), a coating layer can be deposited on the back surface of a non-magnetic substrate without damaging the magnetic metal thin film.

This makes it possible to improve the running properties of the thin-film magnetic recording medium without damaging the magnetic metal thin film of the medium.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view showing an example of the surface of a gravure roll used in the present invention, and FIG.
3 is a cross-sectional view taken along the line -■, and FIG. 3 is a schematic diagram of a gravure coating method using a conventional gravure roll. 1... Gravure roll, 2... Song part, 3... Open part [Effects of the invention]

Claims (1)

[Claims] (1) In a method of manufacturing a magnetic recording medium having a magnetic metal thin film as a recording layer, when a paint is applied by a gravure roll method to the other side of a non-magnetic substrate on which a magnetic metal thin film layer is formed on one side. The gravure roll is characterized by using a gravure roll shaped so that its surface unevenness satisfies the relationship (area of the part in contact with the non-magnetic substrate)/(area of the part facing the non-magnetic substrate) ≧0.1. A method for manufacturing a magnetic recording medium.