JPH0833993B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferromagnetic metal thin film type magnetic recording medium, and in particular, it significantly reduces defects in a protective layer and a top coat layer provided for improving practical performance after forming a magnetic layer. The present invention relates to a method for manufacturing a magnetic recording medium.

Conventional technology Co, Ni, Fe or alloys containing them as the main component are formed by a vacuum deposition method, a sputtering method, a film formation method in vacuum such as ion plating, or a polymer film such as a polyimide film or a non-magnetic metal. The ferromagnetic metal thin film type magnetic recording medium formed on the substrate made of, for example, can dramatically improve the recording density as compared with the conventional coating type magnetic recording medium.

By the way, the conditions for increasing the recording density are:
In addition to reducing recording and reproduction defects as much as possible,
It is important to reduce spacing loss between magnetic recording media as much as possible, and it is also necessary for magnetic recording to have durability. In order to satisfy these conditions, it is conventionally known to form a protective layer after forming a magnetic layer and further provide a lubricant layer as a top coat layer.

FIG. 4 shows a cross section of a magnetic recording medium in which a protective film by a conventional plasma CVD method and a lubricant layer by a wet coating method are formed, 1 is a substrate, and 2 is a ferromagnetic metal thin film layer formed by a vacuum film forming method. 3 is a back coating layer, 4 is a diamond-like carbon film formed by a plasma CVD method, and 5 is a lubricant layer formed by a wet coating method.

An example of the conventional method and apparatus for manufacturing the above-described magnetic recording medium will be described below with reference to FIGS. 4 and 5.

First, an apparatus for applying the diamond-like carbon film 4 by the conventional plasma CVD method will be described with reference to FIG. Reference numeral 10a denotes a magnetic recording medium before the formation of the protective layer 4, which is wound around the feeding roller 11. Numerals 12 and 14 are pass rollers, which are in contact with the ferromagnetic thin film layer 2 of the magnetic recording medium 10 and are rotating. A main roller 13 is insulated from the main body of the apparatus, and applies a voltage between the main roller and the ferromagnetic metal thin film layer 2 to convey them while closely contacting each other. A take-up roller 15 continuously takes up the magnetic recording medium 10b having the protective layer 4 formed thereon. Reference numeral 16 is a plasma generating nozzle, 17 is an electrode, 18 is a gas inlet, and 19 is a plasma power source. These various constituent elements 16 to 19 form a processing unit for forming the protective layer 4. A bias power source 40 applies a voltage between the main roller 13 and the ferromagnetic metal thin film layer 2 of the magnetic recording medium 10, and is provided outside the vacuum chamber together with the plasma power source 19.

Next, a method of manufacturing a magnetic recording medium by the conventional plasma CVD method using the apparatus configured as described above will be described.

The magnetic recording medium 10a before the formation of the protective layer 4 that has been fed from the feeding roller 11 passes through the pass roller 12 and then is applied to the main roller 13 with a voltage applied between the main roller 13 and the ferromagnetic metal thin film layer 2. It is closely and continuously sent.
On the other hand, the ion current of the plasma for forming the protective layer 4 is generated by the reaction gas from the gas introduction port 18 and the applied voltage from the plasma power source 19, and is sent from the plasma nozzle 16 to the ferromagnetic metal thin film layer 2 of the magnetic recording medium 10a. And the diamond-like carbon film 4 is formed. Then, the magnetic recording medium 10b having the protective layer 4 formed thereon is wound around the take-up roller 15 via the pass roller 14.

The magnetic recording medium having the diamond-like carbon film 4 formed by the plasma CVD method is loaded / unloaded from the plasma CVD apparatus at once, and the lubricant layer is formed by the wet coating apparatus.

However, according to the above-mentioned conventional method, active species, ions, etc., which are deviated from the plasma nozzle at the time of forming the diamond-like carbon film 4, adhere weakly to the ferromagnetic metal thin film layer 2 of the magnetic recording medium 10a, The back coating surface adheres when wound up. In addition, active species, ions, and the like that have leaked from the nozzle are scattered throughout the vacuum chamber and adhere to the magnetic recording medium. Contaminants such as these deposits and water weaken the bond between the diamond-like carbon film and the lubricant layer, and the deposits themselves are wound up after the lubricant layer is formed, and also when traveling by VTR, Transfer and dropouts occur, and especially during reproduction with a VTR, the adhered matter adheres to the head, causing not only output fluctuation but also head clogging, which causes a serious defect as a magnetic recording medium.

In view of the above problems, the present invention reduces the transfer of adherents with weak binding force due to leakage of active species and ions during formation of the protective layer, particularly, the transfer to the back coating surface during winding, thereby regenerating on a VTR. It is an object of the present invention to provide a method for manufacturing a magnetic recording medium in which head adhesion is reduced and output fluctuations and head clogging are significantly reduced.

Means for Solving the Problems In order to solve the above problems, the method of manufacturing a magnetic recording medium of the present invention is a method of manufacturing a magnetic recording medium having a ferromagnetic metal thin film formed on a non-magnetic substrate, while performing the above-mentioned strong process by a plasma CVD method. It is characterized in that a diamond-like carbon film is formed on the magnetic metal thin film, a lubricant layer is continuously formed on the diamond-like carbon film in the same vacuum chamber by a vacuum evaporation method, and the lubricant layer is wound on a roller.

Effect According to the present invention, by forming the lubricant layer by vacuum deposition immediately after forming the protective layer on the magnetic recording medium by the plasma CVD method, the protective layer is covered with the lubricant layer before the magnetic recording medium is wound up. Since the molecules of the protective layer are wrapped in the lubricant and maintain a stable state, the deposits generated during the formation of the protective layer are
Since it is hardly transferred to the back coating surface during winding and does not adhere to the head, output fluctuation and head clogging are prevented.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an outline of a device configuration in an embodiment of the present invention. The basic structure of the magnetic recording medium 20 manufactured in this embodiment is the same as that of the conventional one shown in FIG.
A film is used as the substrate 1, a ferromagnetic metal thin film layer is formed on the surface by oblique vapor deposition of a Co-Ni alloy of 0.1 to 0.2 μm, and a back coating layer made of a mixture of resin and carbon is formed on the back surface to improve runnability. 3 is a magnetic recording medium 20 on which the diamond-like carbon film 4 is formed on the ferromagnetic metal thin film layer 2.
And the lubricant layer 5 is formed.

In FIG. 1, reference numeral 20a denotes a magnetic recording medium before the diamond-like carbon film 4 and the lubricant layer 5 are formed. The magnetic recording medium 20a is wound around a feeding roller 21 and the tension of the feeding roller 21 is controlled to 0.5 to 20 Kgf in terms of a width of 500 mm. It has been sent out. Numerals 22 and 24 are pass rollers which rotate in close contact with the magnetic recording medium 20. Reference numeral 23 is a main roller, on the surface of which a dielectric film is provided. A voltage of DC-0.05 to 3 KV is applied to the main body of the roller 23 from the bias power source 30, while the roller 23 is rotationally controlled so as to convey the magnetic recording medium 20 at a constant speed (0.1 to 200 m / min). Reference numeral 25 is a roller for continuously winding up the magnetic recording medium 20b after forming the protective layer 4 and the lubricant layer 5, the tension is controlled to 0.5 to 20 Kgf in terms of a width of 500 mm, and the taper tension can be controlled. Reference numeral 26 is a plasma nozzle for forming the diamond-like carbon film 4, 27 is a plasma generating electrode, which is connected to a plasma generating power supply 29. This plasma generating power source 29 can apply a voltage of effective value 0.05 to 7 KV by DC, AC, RF or superposition thereof. Reference numeral 28 is a gas inlet, which is a reactive gas such as H ₂ Ar or CH or a vaporized gas such as ketone or alcohol which is 0.5 to 0.001 Torr.
It is introduced with a partial pressure of. 31 is an evaporation source, and is filled with a fatty acid, a fatty acid ester, a fatty acid amide, etc. as a lubricant. Reference numeral 32 denotes an evaporation source heating device for melting and evaporating the lubricant of the evaporation source 31, and the heating intensity thereof is controlled by detecting the temperature of the evaporation source. 33 is a protective plate,
Evaporated particles of the lubricant prevent contamination of the magnetic recording medium in the vacuum chamber or the component parts carrying it. The evaporation rate monitor 34 detects the evaporation amount of the lubricant particles and controls the temperature of the evaporation source. Reference numeral 35 denotes a shutter, which is opened after reaching a predetermined evaporation rate to start vapor deposition of the lubricant on the protective layer of the magnetic recording medium.

The operation of the method and apparatus for manufacturing the magnetic recording medium of the present invention configured as described above will be described with reference to FIG.

The magnetic recording medium 20a before the formation of the protective layer and the lubricant layer is in close contact with the main roller 23 to which a voltage is applied from the bias power source 30 on the back surface of the ferromagnetic metal thin film layer 2, and is directed from the feeding roller 21 to the winding roller 25. It is being transported continuously. On the other hand, the ion current of the plasma for forming the diamond-like carbon film 4 is generated by the reactive gas from the gas inlet port 28 and the voltage applied from the plasma power supply 29, and the plasma nozzle 26 for forming the diamond-like carbon film 4 is generated. Reaching the ferromagnetic metal thin film layer 2 of the magnetic recording medium 20a facing each other,
The diamond-like carbon film 4 is formed. The lubricant layer 5 is formed immediately after the protection layer 4 is formed on the main roller 23. The lubricant for forming the lubricant layer 5 is filled in the evaporation source 31, is heated and melted by the heating device 32, and when the evaporation rate monitor 34 reaches the specified evaporation rate, the shutter is released.
35 is released, and the lubricant layer 5 is formed immediately after the protective layer 4 is formed on the ferromagnetic metal thin film layer 2. As described above, by forming the lubricant layer immediately after forming the protective layer, the magnetic recording medium
Since the protective layer 4 is covered with the lubricant layer 5 before the 20 is taken up by the take-up roller 25, most of the deposits due to leakage of active species and ions when the protective layer 4 is formed are transferred to the back coating layer 3 surface. The protective layer 4 and the lubricant layer 5 can be formed without using them.

Next, the effects of the above-described embodiment will be described with reference to FIGS.
This will be described with reference to the drawings.

2 and 3, a diamond-like carbon film having a thickness of about 100Å is used as a protective film according to the method of the present invention and the conventional example. Gas introduction pressure 0.1 Torr Applied voltage is 1 KV in total with bias.
The magnetic recording media 10 and 20 formed with a stearic acid film as a lubricant layer with a thickness of about 30Å show the head clogging and the degree of head contamination when recording and reproducing using a video tape recorder. is there. As a specific condition, a magnetic recording medium 10 or 20 with a length of about 90 minutes and a width of 8 mm is
Run at 14mm / sec, relative speed 3.8m / sec, track pitch approx.
It shows the data when a video signal was recorded with a rotating cylinder type video tape recorder at 20 μm and reproduced for about 200 hours. FIG. 2 shows the integrated value of the head clogging time, and FIG. 3 shows the contamination degree of the head. The head clogging time is the accumulated time when the reproduction output is reduced by 6 dB for a finite time, and the head contamination degree means that the lubricant layer 5, the back coating layer 3, etc., which are missing from the magnetic recording medium on the head surface or the periphery. It is an index of the amount of adhering and staying.

It was confirmed from Fig. 2 that the head clogging after running for 100 hours or more was significantly reduced (1/10 or less) and that the practical limit could be cleared with a margin. Further, in the magnetic recording medium manufactured by the method of the conventional example, the output fluctuation appears from around the time when the head clogging occurs and increases, and the amplitude increases with the number of running times and the increase.

As shown in FIG. 3, the head contamination saturates after running about ten times and is extremely stable thereafter. However, with the method of the conventional example, it increased to about 100 times, and then increased and decreased repeatedly.

As is clear from the above experimental results, according to the present invention, the deposits deposited on the protective layer 4 during film formation on the protective layer 4 are transferred to the back coating surface at the time of winding, and this is transferred at the time of running on the video tape recorder. Since the phenomenon of gradual chipping, sticking to the head, and finally clogging of the head is prevented, a large output fluctuation does not occur within the practical limit. In this case, the transfer or loss of the adhered matter adhered on the protective layer is prevented because it is considered that the adhered matter has a very small number of molecules, so that the lubricant is wrapped in the lubricant during the formation of the lubricant layer, and stable It is thought that this is because the state is maintained.

EFFECTS OF THE INVENTION As described above, according to the present invention, after forming a metal thin film of a magnetic recording medium, a method of forming a lubricant layer immediately after forming a protective layer on a ferromagnetic metal thin film allows back coating of deposits during formation of the protective layer. It is possible to prevent transfer to the surface and adhesion to the head,
In addition, the diamond-like carbon film and the lubricant layer are chemically strongly bonded to each other, and an extremely clean lubricant layer is formed, which significantly reduces head clogging during recording / reproduction with a video tape recorder, which causes a problematic output. Since the occurrence of fluctuations is eliminated, good recording / reproducing characteristics can be obtained for a longer time.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a device configuration in one embodiment of the present invention, FIG. 2 is a comparison diagram between a conventional example and an embodiment of the present invention regarding the number of times of running and head clogging, and FIG. 3 is the number of times of running. And FIG. 4 is a cross-sectional view showing the structure of the magnetic recording medium, and FIG. 5 is a schematic view showing a magnetic recording medium manufacturing apparatus by a conventional protective layer forming method. 1 ... Non-magnetic substrate, 2 ... Ferromagnetic metal thin film layer, 4 ... Diamond-like carbon film, 5 ... Lubricant layer, 20 ... Magnetic recording medium, 21 ... Delivery roller, 22,24 ... Pass roller, twenty three
...... Main roller, 25 ...... Winding roller, 27 ...... Plasma generation electrode, 28 ...... Gas inlet, 29 ...... Plasma power supply, 31 ...... Evaporation source, 32 ...... Heating device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-259831 (JP, A) JP-A-62-219330 (JP, A) JP-A-63-34728 (JP, A)

Claims (1)

[Claims] 1. A diamond-like carbon film is formed on the ferromagnetic metal thin film by a plasma CVD method while running a magnetic recording medium having a ferromagnetic metal thin film formed on a non-magnetic substrate,
Further, in the same vacuum chamber, a lubricant layer is continuously formed on the diamond-like carbon film by a vacuum vapor deposition method, and the lubricant layer is wound around a roller.