JPH02148414A - Production of perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To form the excellent magnetic recording medium without wrinkles by allowing a magnetic layer to travel along a heating roller to form an oxide layer thereon and forcibly cooling the layer on the inlet or outlet side of the heating roller or both sides thereof. CONSTITUTION:The oxide layer is formed by allowing the magnetic layer to travel along the heating roller 13 and a high-polymer substrate is forcibly cooled on the inlet or outlet side of th heating roller 13 or both sides thereof. Namely, cooling air flow is blown from the inlet and outlet sides of the heating roller 13 provided with cooling nozzles 11 on both sides of the roller 13 to cool the substrate. The wrinkling occurring in the abrupt thermal deformation of the high-polymer substrate is prevented in this way and, therefore, the perpendicular magnetic recording medium having excellent magnetic characteristics and practicable characteristics is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a perpendicular magnetic recording medium for forming an excellent magnetic recording medium without wrinkles.

BACKGROUND OF THE INVENTION With the advancement of high-density magnetic recording technology, magnetic recording media are shifting from conventional coating-type recording media to thin-film type recording media. Furthermore, in recent years, consideration has been given to changing the recording method itself, that is, moving from the conventional longitudinal magnetic recording method to the perpendicular magnetic recording method.

The perpendicular magnetic recording medium is a CoCr perpendicular magnetic anisotropic film (hereinafter referred to as C
Research and development is being carried out mainly on oCr film (abbreviated as oCr film).

Co(,+) films can be formed by either sputtering or vacuum evaporation, but vacuum evaporation is particularly suitable for mass production because it can achieve a high film deposition rate of 1 μm/sec or more. That is, as shown in FIG.
A CoCr film can be mass-produced by evaporating CoCr from the evaporator R9 at the front end of the mask 8 while the film is traveling along the circumferential surface of the cylindrical can 7, and then winding it up onto the take-up roll 10.

On the other hand, in order to realize high-density magnetic recording, it is essential to improve the magnetic properties of the magnetic recording medium as well as to ensure practical properties as typified by the head-medium interface. In the case of a CoCr film, the interface is particularly important because the magnetic layer is made purely of metal, and surface oxidation treatment of the medium has been proposed as a means to solve this problem (Honda et al. (IEEE)). Trans, on Magn.
Nov. 1988). That is, by running a vapor-deposited medium along a heating roller in the atmosphere, for example, as shown in FIG. 4, an oxidized layer is formed on the surface of the medium, and this oxidized layer lowers the dynamic friction coefficient of the medium and increases the scratch strength. This leads to an increase in the mechanical durability of the medium during recording and reproduction.

Problem to be Solved by the Invention However, when oxidation treatment is performed using a heating roller, wrinkles tend to form in the polymer substrate on the entrance or exit side of the roller. These wrinkles are thought to be caused by thermal deformation accompanying rapid temperature deformation of the polymer substrate, and the higher the temperature of the heating roller, the more likely the wrinkles will appear. Further, in order to realize high-density recording, the surface properties of polymer substrates are becoming smoother, but the smoother the substrate surface, the more easily the aforementioned wrinkles appear.

The present invention aims to solve similar problems of the prior art.

Means for Solving the Problems The present invention provides a magnetic layer containing at least CO and Cr, or CO, Cr, and Ni as main components, which is formed directly or via an underlayer on a polymer substrate, and the magnetic layer In a method for producing a perpendicular magnetic recording medium, the surface of which is covered with an oxide layer formed by the heating treatment, the oxide layer is formed by running the magnetic layer along a heating roller, and This method of manufacturing a perpendicular magnetic recording medium is characterized by forcibly cooling the entrance or exit side of the roller or both thereof.

According to the present invention, since the medium is cooled on the entry side and/or the exit side of the temperature raising roller, it is possible to prevent wrinkles caused by rapid thermal deformation of the polymer substrate.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an embodiment of the present invention, which differs from FIG. 3 which shows a conventional example in that cooling nozzles 11 are provided on both sides of a heating roller 13. In the oxidation treatment of a perpendicular magnetic recording medium in which a C0CrN film with a thickness of 250 nm was provided on a polyimide substrate with a thickness of 107 zm, the temperature of the heating roller during the oxidation treatment was 320'C, the medium running speed was 1 m/min, and the entrance and exit sides of the heating roller were A stream of cold air was blown from the side. The cold air flow was generated using a refrigerator. When the temperature and air volume of the cold air flow were changed, if the substrate temperature measured by the temperature measurement sticker attached to the medium in advance was 200'C or less near the entry side of the heating roller, wrinkles would occur on the entry side of the heating roller. Similarly, if the substrate temperature was 250'C or less near the exit side of the heating roller, wrinkles did not occur on the exit side of the heating roller.

FIG. 2 shows another embodiment of the present invention, which differs from FIG. 4 which shows the conventional example in that cooling nip rollers 12 are provided on both sides of the heating roller 13.

In the oxidation treatment of a perpendicular magnetic recording medium in which a CoCr layer with a thickness of 250 nm is provided on a polyimide substrate with a thickness of 10 μm, the heating roller entry side and The temperature of the nip roller on the exit side was changed. When the temperature of the entry side nip roller exceeded 200'C, the wrinkles on the heating roller entry side did not disappear, but when the temperature of the entry side nip roller was set to 200'C or less, no wrinkles were generated on the heating roller entry side.

Similarly, for the exit nip roller, set its temperature to 2506.
C or less, it was possible to eliminate wrinkles on the exit side of the heating roller.

Effects of the Invention As described above, according to the method for manufacturing a perpendicular magnetic recording medium of the present invention, wrinkles that occur during surface oxidation treatment can be prevented, so that a perpendicular magnetic recording medium having excellent magnetic properties and practical properties can be formed. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the oxidation treatment step in an embodiment of the method for manufacturing a perpendicular magnetic recording medium of the present invention, and FIG. 2 is another example of the oxidation treatment step in the method for manufacturing a perpendicular magnetic recording medium of the present invention. FIG. 3 is a diagram showing a method of depositing a magnetic layer by a continuous deposition method, and FIG. 4 is a diagram showing a conventional example of surface oxidation treatment. l...exhaust system, 2...vacuum chamber, 3...rotation direction,
4... Unwinding roll, 5... Polymer substrate, 6...
Guide roller, 7... Gyan, 8... Mask, 9.
... Evaporation source, 10... Winding roll, 11... Cooling nozzle, 12... Cooling nip roller, 13...
・Heating roller, 1/L: Vapor-deposited medium. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1 Figure 2 Figure Figure

Claims (5)

[Claims] (1) A magnetic layer containing at least Co and Cr, or Co, Cr, and Ni as main components is formed directly or through an underlayer on a polymer substrate, and the surface of the magnetic layer is formed by heat treatment. In a method for manufacturing a perpendicular magnetic recording medium covered with an oxide layer, the oxide layer is formed by running the magnetic layer along a temperature raising roller, and A method for manufacturing a perpendicular magnetic recording medium, characterized in that the polymer substrate is forcibly cooled on both sides. (2) The method for manufacturing a perpendicular magnetic recording medium according to claim 1, characterized in that a cold air stream is used as the cooling means. (3) The method for manufacturing a perpendicular magnetic recording medium according to claim 1, characterized in that a nip roller is used as the cooling means. (4) The method for manufacturing a perpendicular magnetic recording medium according to claim 1, 2 or 3, wherein the substrate temperature on the entry side of the heating roller is 200° C. or less. (5) The method for manufacturing a perpendicular magnetic recording medium according to claim 1, 2 or 3, wherein the substrate temperature on the exit side of the temperature raising roller is 250° C. or less.