JPH0364934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic layer mainly composed of Co and Cr, the axis of easy magnetization of which is perpendicular to the film surface, is formed on a substrate made of a polymeric material. The purpose of this is to remove curls that occur during the manufacturing process of magnetic recording media and have an adverse effect on the running performance, winding performance, magnetic head touch, etc. of the media.

As a magnetic recording method with excellent short wavelength recording characteristics,
There is a perpendicular recording method. This method requires a perpendicular recording medium whose axis of easy magnetization is perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented perpendicular to the film surface of the medium, so the shorter the signal wavelength, the smaller the demagnetizing field within the medium.
Excellent playback output can be obtained.

If a magnetic layer mainly composed of Co and Cr is formed by sputtering or vacuum evaporation (including methods such as ion plating that ionizes some of the evaporated atoms), it can be easily magnetized in the direction perpendicular to the film surface. It is known that a perpendicularly magnetized film with an axis can be obtained, but in order to obtain a perpendicularly magnetized film with excellent properties and high coercive force, it is necessary to raise the substrate temperature to a high temperature during thin film formation in any method. is necessary. In other words, in the sputtering method, approximately
The temperature needs to be 100°C or higher, or about 180°C or higher in the case of vacuum evaporation. Although this level of substrate temperature is not a problem when using a substrate made of a non-magnetic metal such as Al, it cannot be used with a substrate made of a polymeric material with poor heat resistance such as polyethylene terephthalate because it causes heat loss. Therefore, when using a substrate made of a polymer material, it is limited to a heat-resistant substrate such as polyamide or polyimide.
Co-Cr was actually deposited on a substrate made of polyamide-based polymer material by vacuum evaporation at a substrate temperature of 200°C.
A film was formed, but the coercive force perpendicular to the film surface was
A perpendicular magnetization film of 800 Oe was obtained. However, as shown in FIG. 1, the obtained medium is curled so that the Co--Cr perpendicular magnetization film 1 is on the inside, and when this medium is used as a magnetic recording medium, the above-mentioned problems occur. Note that 2 is a substrate made of a polyamide-based polymer material. Even if it is made by sputtering method, it is the first
A curled medium as shown in the figure is obtained. In order to use it as a magnetic recording medium, when the amount of curl is expressed as t/l using t and l shown in FIG. 1, it is necessary that t/l is 10% or less.
In order to satisfy this condition, the substrate 2 may be shrinked by heat treatment after the thin film is formed, but in order to shrink a substrate made of a heat-resistant polymer material such as polyamide, it is necessary to heat the substrate 2 at a high temperature of 300°C or higher. There must be. Further, as a result of experiments, it has become clear that preferable results can be obtained by performing the treatment at as high a temperature as possible (but below the temperature at which the polymeric material decomposes) and in a short time. Conventionally, this type of treatment was carried out by running the medium along the circumferential side of a high-temperature cylindrical can, but it was difficult to raise the temperature of the cylindrical can to over 300°C. However, there was a problem in that curls could not be removed during the process of forming the magnetic layer by vacuum deposition or the like. The present invention attempts to remove curls generated on the substrate during the process of forming the magnetic layer by easily increasing the substrate temperature to 300°C or higher and performing treatment in a short time even after the magnetic layer is formed. The present invention will be explained using the drawings.

FIG. 2 shows an example of the manufacturing method according to the present invention.
In the figure, numerals 3 and 4 are a supply roll and a take-up roll for a recording medium 5 made of a heat-resistant polymer substrate 2 on which a perpendicularly magnetized film is formed, respectively.
Reference numeral 6 denotes a light source such as a halogen lamp or a xenon lamp, and the light emitted from the light source is collected by a condenser 7 to irradiate and heat the polymer substrate 2. Since the substrate 2 has a metal thin film as a perpendicularly magnetized film, it can be heated to a temperature of 300° C. or higher easily and in an extremely short time using focused light. Therefore, the heat-resistant polymer substrate undergoes thermal shrinkage and curls generated on the substrate 2 during the manufacturing process can be removed. Note that the amount of curl removal is adjusted based on the irradiation range and intensity of light, which can be adjusted by the feeding speed of the medium, the power supplied to the light source, the distance between the substrate and the light source, and the like. Note that the curl removal treatment shown in FIG. 2 in the manufacturing method of the present invention can also be performed at atmospheric pressure.

Next, examples will be described. A Co-Cr film with a thickness of 1500 Å was deposited on a substrate made of polyamide polymer material with a thickness of 12 μm at a substrate temperature of 200°C by vacuum evaporation method.
When a perpendicularly magnetized film is formed, a curl with a t/l of about 80% occurs. This substrate was subjected to curl removal treatment using the apparatus shown in FIG. However, a 500 W halogen lamp was used as the light source, the substrate feeding speed was 5 m/min, and the distance between the substrate and the lamp was 8 cm. The magnetic recording medium obtained through such treatment had a curl amount t/l of about 3%.

Although FIG. 2 shows the simplest example in which the substrate 2 runs not along a support, there is no problem even if the board 2 runs along a support such as a cylindrical can.

As described above, according to the present invention, curls generated on the substrate can be removed by irradiating the substrate with focused and narrowly focused light and heating it, so magnetic recording with almost no curls can be achieved. Medium can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the state of curl in a magnetic recording medium, and FIG. 2 is a first example of the manufacturing method according to the present invention.
It is a figure which shows an example. 1... Perpendicular magnetization film, 2... Substrate, 6... Light source,
7... Light collector.

Claims (1)

[Claims] 1 Co and Cr whose easy axis of magnetization is perpendicular to the film surface
A magnetic recording medium characterized in that a substrate made of a polymeric material on which a magnetic layer containing as a main component is formed is heated by being focused by a condenser and irradiated with narrowly narrowed light. manufacturing method.