JPS6326825A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease noise even at the time of high-density magnetic recording by cooling a cylindrical can with a refrigerant and consisting a heat transmission path of copper coated with a diamond-like hard carbon coating film at the time of forming a magnetic layer by a sputtering method or the like while moving a high-polymer film along the cylindrical can. CONSTITUTION:The diamond-like hard carbon coating layer 16 is provided on the side of the outside cylinder 15 constituted of Cu where the cylinder contacts the high- polymer film 14 and the surface of the Cu is roughened to increase the contact area on the side where the cylinder contacts the refrigerant 18. The inside cylinder 17 is constituted of a nonmagnetic stainless steel and is applied with the vapor flow 19 which is limited in the min. incident angle by a mask 20. A polyethylene terephthalate film having 11mum thickness is moved along the cylindrical can formed by using the outside cylinder 15 having 50cm outside diameter, finishing the surface of the Cu having 10mm wall thickness to 0.06S roughness and forming the diamond-like hard carbon coating film thereon to 100mu thickness while 'NAIBURAIN(R)' cooled to -20 deg.C is circulated at 1.4m<3>/min in said can, then Co-Ni (N=20wt%) is deposited thereon by electron beam evaporation to 0.6mum in low-pressure oxygen at 40 deg. min. incident angle.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium whose magnetic recording layer is a ferromagnetic thin film suitable for high-density magnetic recording.

Conventional technology In the field of magnetic recording, higher densities are being achieved through shorter wavelengths and narrower tracks, and thin film media with high coercive force and low demagnetization are strongly desired. 2. Description of the Related Art A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film obtained by oblique vapor deposition using a vapor deposition method, a so-called vapor-deposited tape (hereinafter referred to as ME tape), has been attracting attention.

FIG. 2 is a schematic diagram of a vapor deposition apparatus used for manufacturing conventional ME tape. In Figure 2, 1 is a polymer film, 2 is a feeding shaft, 3 is a winding shaft, 4 is a cylindrical can,
6 is an outer cylinder, 6 is an inner cylinder, 7 is a refrigerant circulation path, 8 is an evaporation source container, 9 is a vapor deposition material, 1o is a mask that defines the minimum incident angle for oblique evaporation, 11 is a vacuum exhaust system, 12 is a free roller, and 13 is a vacuum container.

A method for producing a vapor deposition tape using the vapor deposition apparatus shown in FIG. 2 will be outlined. The inside of the vacuum container 13 is maintained in a vacuum by the evacuation system 11, but if necessary, oxygen gas or the like is intentionally introduced from the outside to provide an equilibrium pressure.

The vapor deposition material 9 is vaporized by electron beam heating, and the mask 1
It is subjected to oblique evaporation with a minimum incident angle defined as 0. Oblique deposition is performed on the polymer film 1 along the cylindrical can 4. In order to protect the low melting point polymer film from thermal damage, a concentric cylinder made of non-magnetic stainless steel is used. A large amount of cooling refrigerant is circulated through the refrigerant circulation path between 5° and 6°, and the polymer film is cooled by contact conduction.

Problems to be Solved by the Invention However, with the above configuration, the deposition rate increases to 0.5 μ/sec or more, and when polyethylene terephthalate is used as the polymer film, modulation noise of the resulting magnetic recording medium increases. There is a problem in that the shorter the wavelength, the greater the variation, and an improvement has been desired.

The present invention has been made in view of the above-mentioned circumstances, and provides a method for manufacturing a magnetic recording medium that can produce a large amount of media with improved modulation noise when subjected to high-density magnetic recording.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a magnetic recording medium of the present invention employs an electron beam evaporation method or a sputtering method while moving a polymer film along a cylindrical can. When forming the magnetic layer, the cylindrical can is cooled with a refrigerant.
At the same time, the heat transfer path is made of copper coated with diamond-like hard carbon.

Effect The present invention has the above-described configuration, so that the cooling effect is uniform,
In addition, since the cooling surface is made of copper and a diamond-like hard carbon coating that has extremely good heat transfer, the temperature gradient can be reduced, so the temperature rise of the polymer film can be suppressed and controlled in the longitudinal direction as well. In addition, the surface is made of diamond-like hard carbon, which has good wear resistance, and the roughness of the cooling surface can be maintained constant, so heat transfer is constant from that point of view, so the magnetism of the magnetic recording medium is Characteristics can be made uniform, modulation noise can be improved, and the effects can be obtained over a large area.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged view of a vapor deposition apparatus used to carry out the present invention. In FIG. 1, 14 is a polymer film, 15 is an external cylinder made of copper, and a diamond-shaped hard carbon coating layer 16 is arranged on the side in contact with the polymer film, and the contact area is on the side in contact with the refrigerant 18. The copper surface is made rough so as to increase the Reference numeral 17 indicates an inner cylinder made of non-magnetic stainless steel, and reference numeral 19 indicates a vapor flow whose minimum incident angle is limited by a mask 2o.

The outer diameter of the outer cylinder is 601, the surface of copper with a wall thickness of 10H is finished to a roughness of 0.063, and a 100 μm diamond-like hard carbon coating is formed on the cylindrical can.
1.4nl/win of knife line cooled to 20°C
While circulating the polyethylene terephthalate film with a thickness of 11 μm,
-Ni (Ni2o wt%) at 1,6X
0.16 μm electron beam evaporation was performed at a rate of 2 μm/sea in oxygen at 10 (Torr).

The polyethylene terephthalate film used had a width of 5
Q CM, 4500m long, was tape-recorded and the modulation noise at 100 randomly selected locations was compared.

In order to clarify the effects of the present invention, magnetic tape was similarly constructed using a conventional manufacturing equipment configuration in which only the cylindrical can was made of stainless steel with hard chrome plating, with the same dimensions. Manufactured. Regarding this as well, modulation noise was measured at 100 arbitrary locations. Relative speed 3.
Recording a 6MHz signal at 8m/Be, band 9M
In the magnetic recording medium according to this embodiment, the modulation noise at l-[z is -75(dB) when the signal output is o (dB).
B) It is stable in the range of 1 to 2 (dB), while the comparative example ranges from -75,9 (dB) to -75,9 (dB).
There was wide variation.

As another comparison, six rolls of 5oα width x 4500m length were prepared, magnetic tapes were manufactured using the manufacturing method of the present invention and the conventional method, and the modulation noise was similarly arbitrarily extracted.
When measurements were taken at 100 points per roll, the magnetic tape according to the present invention had a variation of 5.7 inches between rolls, while the conventional method had a variation of 37 inches between rolls.

In the above examples, polyethylene terephthalate was used as the polymer film, but polypropylene,
Polycarbonate, polyethylene naphthalate, polyamideimide, polyimide.

The same effect can be obtained using polyphenylene sulfide or the like.

It is also suitable for forming a perpendicularly magnetized film such as Go--Cr by sputtering instead of electron beam evaporation, and for forming an in-plane magnetized film such as Go--Ni by sputtering. This is particularly effective when speeding up sputtering.

Effects of the Invention As described above, the manufacturing method of the present invention has the excellent effect that magnetic recording media with less modulation noise can be obtained in large quantities during high-density magnetic recording.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part of an example of a vapor deposition apparatus used for carrying out the present invention, and FIG. 2 is a schematic configuration diagram of an example of a vapor deposition apparatus used for manufacturing a vapor deposition tape. 14...Polymer film, 15...External cylinder (copper), 16...Diamond-shaped hard carbon broken layer. Name of agent: Patent attorney Toshio Nakao and one other attorney
ri θ 1″′″ − Mamoru ■

Claims (1)

[Claims] When forming a magnetic layer by electron beam evaporation or sputtering while moving a polymer film along a cylindrical can, the cylindrical can is cooled with a refrigerant and the heat transfer path is coated with diamond-like hard carbon. A method for manufacturing a magnetic recording medium, characterized in that it is made of copper.