JP2505024B2 - Method and apparatus for manufacturing magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a ferromagnetic metal thin film type magnetic recording medium, and in particular, protection for improving practical performance after forming a magnetic layer. The present invention relates to a method and an apparatus for manufacturing a magnetic recording medium capable of significantly reducing layer defects.

[Prior art] Co, Ni, Fe or alloys containing them as the main component are formed into a polymer film such as a polyester film or a polyimide film by a vacuum deposition method such as vacuum deposition method, sputtering, or ion plating. The ferromagnetic metal thin film type magnetic recording medium formed on a substrate made of magnetic metal or the like can dramatically improve the recording density as compared with the conventional coating type magnetic recording medium.

By the way, as a condition for increasing the recording density, it is important to reduce recording / reproducing defects as much as possible and also reduce spacing loss between the magnetic head and the recording medium as much as possible. In addition, it is necessary that the recording medium also has durability. Conventionally, in order to satisfy these conditions, a protective layer is formed after forming the magnetic layer, and a plasma CVD method or a sputtering method is known as a forming method thereof.

FIG. 7 shows the structure of a magnetic recording medium having a protective layer formed by these conventional methods. Reference numeral 1 is a substrate, 2 is a ferromagnetic metal thin film layer formed by a vacuum film formation method, and 3 is a back surface. The coating layer 4 is a protective layer formed by a plasma CVD method or a sputtering method, and 5 is a lubricating layer formed after the protective layer 4 is formed.

An example of the conventional method and apparatus for manufacturing the above-described magnetic recording medium will be described below with reference to the plasma CVD method with reference to FIGS. 7 and 8.

First, a conventional manufacturing apparatus using the plasma CVD method will be described with reference to FIG. Reference numeral 10a denotes a magnetic recording medium before formation of a protective layer, which is wound around a feeding roller 11. Numerals 12 and 14 are pass rollers which are in contact with the ferromagnetic metal 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 a voltage is applied between the main roller and the ferromagnetic metal thin film layer 2.
They are transported while closely contacting each other. A winding roller 15 continuously winds up the magnetic recording medium 10b on which the protective layer has been formed. 16 is a plasma nozzle, 17 is an electrode, 18 is a gas inlet, 19 is a power source for plasma, each of these components 16 ~
A processing unit for forming a protective layer is formed by 19. 40 is a power source for bias and applies a voltage between the main roller 13 and the ferromagnetic metal thin film layer 2 of the magnetic recording medium 10.
It is provided outside the vacuum chamber together with the plasma power supply 19.

Subsequently, a method of manufacturing a magnetic recording medium by a 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, which is fed from the feeding roller 11, passes through the pass roller 12 and then the main roller 1
With a voltage applied between 3 and the ferromagnetic metal thin film layer 2,
It is fed in close contact with the main roller 13 and continuously. On the other hand, the ionic current of the plasma for forming the protective layer is generated by the reaction gas from the gas inlet 18 and the applied voltage from the plasma power source 19, and is ferromagnetic of the magnetic recording medium 10a sent from the plasma nozzle 16. The metal thin film layer 2 is reached and the protective layer 4 is formed. Then, the magnetic recording medium 10b having the protective layer 4 formed thereon is taken up by the take-up roller 15 via the pass roller 14.

On the other hand, the structure of the conventional manufacturing apparatus by the general sputtering method is different from the processing unit having the plasma nozzle 16 shown in FIG. 8 in that it protects metals, carbides, fluorides, etc. for releasing sputtering molecules. The plasma described above is different except that a processing apparatus having a sputtering target made of a layer forming material is provided and that a bias power source is not present.
It is the same as the manufacturing equipment by the CVD method. Further, in the conventional general manufacturing method by the sputtering method, the protective layer 4 of the magnetic recording medium 10 is formed by attaching target material molecules from the sputtering target to the ferromagnetic metal thin film layer 2 and the protective layer. 4 is different from the ferromagnetic metal thin film layer 2 in that power is not supplied to the ferromagnetic metal thin film layer 2.
This is the same as the manufacturing method by the plasma CVD method described above.
Therefore, detailed description of the conventional manufacturing apparatus and manufacturing method by the sputtering method is omitted. In forming the protective layer 4 using the sputtering method, the ferromagnetic metal thin film layer 2
Although a method of performing power supply to a device and a device having a power supply therefor have been developed by the present inventors and applied for a patent, they are not generally known.

[Problems to be Solved by the Invention] The ion current of plasma and the film formation rate are in a substantially proportional relationship, and the ion current is increased under conditions such as increasing the applied voltage for plasma generation. By increasing the voltage applied to the ferromagnetic metal thin film layer of the recording medium 10a, the film formation rate is improved. However, in the conventional main roller 13, when the applied voltage is increased, local current concentration occurs due to defects in the main roller 13 or the magnetic recording medium, and not only the growth of pinholes is promoted, but also the magnetic recording medium. Current concentration that penetrates through the substrate is also generated, which leads to cutting of the magnetic recording medium. Further, if the applied voltage between the magnetic recording medium 10a and the main roller is reduced to prevent local current concentration, the film forming speed is reduced and the adhesion between the substrate 1 of the magnetic recording medium and the main roller 13 is reduced. Not only will the temperature of the substrate 1 rise and the quality of the film will deteriorate, but also the cutting of the magnetic recording medium due to heat loss will be promoted, so that the film formation speed can be improved, the film chamber can be stabilized, and long processing can be achieved. It did not hold. Further, as a magnetic recording medium, not only dropout and head clogging increase, but also the still life is shortened and the corrosion resistance is deteriorated, so that the magnetic recording medium has serious defects.

In view of the above problems, the present invention makes it possible to process a protective layer having a strong adhesion strength over a long length while improving the film formation rate, and as a magnetic recording medium, with dropout and reduction of head clogging, An object of the present invention is to provide a method and an apparatus for manufacturing a magnetic recording medium capable of improving still durability and corrosion resistance.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the above-mentioned ferromagnetic material is added to a magnetic recording medium 20 in which a ferromagnetic metal thin film layer 2 is formed on a substrate 1 made of a non-magnetic material. The protective layer 4 is formed on the metal thin film layer 2 by a vacuum CVD method such as a plasma CVD method or a sputtering method.
In forming the magnetic recording medium 20, a main roller 23 having a dielectric film having a relative dielectric constant of 2 or more and having a thickness of 0.01 to 3 mm is formed on the surface of the magnetic recording medium 20 while the magnetic recording medium 20 is conveyed in close contact with the main roller 23. The film is formed while power is supplied to the magnetic metal thin film layer 2.

[Function] By providing a dielectric film on the surface of the main roller that conveys closely while feeding power to the magnetic recording medium, prevention of pinholes due to local current concentration, current concentration penetrating the substrate, and substrate temperature It is possible to prevent the substrate from being cut due to heat loss due to the rise, to form a stable protective layer while improving the film formation rate, and to perform long processing.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus used for a method of forming a protective layer by a plasma CVD method as a vacuum film forming method which is a first embodiment of the present invention. Since the basic structure of the magnetic recording medium 20 manufactured in the present embodiment is the same as that of the conventional example, a description will be given with reference to FIG. The PET film is used as the substrate 1, the ferromagnetic metal thin film layer 2 is formed on the surface by oblique vapor deposition of Co-Ni alloy of 0.1 to 0.2 μm, and the back surface is made of a mixture of resin and carbon to improve the running property. The back coating layer 3 is formed. In this magnetic recording medium 20, a protective layer 4 and a lubricant layer 5 are formed on the ferromagnetic metal thin film layer 2.

In FIG. 1, reference numeral 20a denotes a magnetic recording medium before formation of a protective layer, which is wound around a feeding roller 21, and the tension from the feeding roller 21 is about 0.5 to 20 in terms of a width of 500 mm.
It is sent out under the control of kgf. Numerals 22 and 24 are pass rollers which rotate in close contact with the magnetic recording medium 20a. Reference numeral 23 is a main roller, and as shown in FIG. 2, the surface has a thickness of 0.01 to 3 mm.
The dielectric film 23a is provided. The dielectric film 23a is formed by coating Al ₂ O ₃ , ZrO ₂ SiC, SiO ₂ , BaTiO ₄ , an inorganic substance of diamond-like carbon, or a resin such as PET, nylon, or polyimide having a relative permittivity of 2 or more, The surface is finished to 2S or less. Further, the main roller 23 is applied with a voltage of DC −0.05 to −3 KV from the bias power source 30 to the main body thereof, while keeping the magnetic recording medium 20a at a constant speed (0.1 to
The rotation is controlled so that it is transported at 200 m / min). 25 is
The roller is a roller that continuously winds up the magnetic recording medium 20b after the formation of the protective layer, and its tension is controlled to 0.5 to 200 kgf in terms of a width of 500 mm, and the taper tension can also be controlled. Reference numeral 26 is a plasma nozzle for forming a protective layer, and 27 is an electrode for plasma generation, which is connected to a power source 29 for plasma generation. The plasma generating power supply 29 can apply a voltage of an effective value of 0.05 to 7 KV by DC, AC, RF, or superposition thereof. Reference numeral 28 denotes a gas inlet, which introduces a reactive gas such as H ₂ or CH or a vaporized gas such as ketone or alcohol at a partial pressure of 0.5 to 0.001 Torr.

Next, a method of manufacturing the magnetic recording medium 20 using the manufacturing apparatus configured as described above will be described with reference to FIG. 1 together with the operation of the manufacturing apparatus.

The magnetic recording medium 20a before forming the protective layer is a bias power source 30.
The back surface of the ferromagnetic metal thin film layer 2 is in close contact with the main roller 23 to which a higher voltage is applied, and while the voltage is applied via the main roller 23, it continues from the feeding roller 21 toward the winding roller 25. Will be transported. On the other hand, the ion current of the protective layer forming plasma is generated by the reactive gas from the gas introduction port 28 and the voltage applied from the plasma power source 29, and the magnetic recording is located opposite to the protective layer forming plasma nozzle 26. Upon reaching the ferromagnetic metal thin film layer 2 of the medium 20a, the protective layer 4 is formed. At this time, the main roller 23
Since the dielectric film 23a having a thickness of 0.01 to 3 mm is provided on the surface of, the local current concentration is small and the current concentration penetrating the substrate 1 is completely eliminated, so that the applied voltage of the bias power supply 30 can be increased. It is possible to improve the film forming speed, the adhesion between the main roller 23 and the magnetic recording medium 20 is strengthened, the temperature rise of the substrate 1 is reduced due to the cooling effect, and the magnetic recording medium 20 is cut due to heat loss. Disappeared,
The protective layer 4 having high adhesion strength and few defects can be formed. The magnetic recording medium 20b having the protective layer 4 formed in this manner is wound up by the winding roller 25 via the pass roller 24.

When the thickness of the dielectric film 23a provided on the surface of the main roller 23 is 0.01 mm or less, pinholes are often generated during coating, which is not practical. Further, when the thickness is 3 mm or more, the adhesion force due to the electrostatic force with the magnetic recording medium 20 has a relative permittivity of 2 and even if the applied voltage to the main roller 23 is 3 KV, it is 1 Kg.
It becomes less than W, leading to cutting due to heat loss of the substrate 1. Fourth
The figure shows the thickness of the dielectric film 23a, the main roller 23 and the substrate 1.
FIG. 7 is a diagram showing the strength of the adhesion force due to the electrostatic force between and with the applied voltage as a parameter when the relative permittivity is constant. According to Coulomb's law, if the electrostatic force of the main roller 23 is F, then F = Q · E = ε _S ε _O AV ² / l ² .

Here, Q is the electric charge, E is the strength of the electric field, ε _S is the relative permittivity, ε _O is the vacuum permittivity, A is the contact area, V is the applied voltage, and 1 is the thickness of the dielectric film.

Fig. 4 shows that ε _S = 2, ε _O = 8.855 × 10 ^-12 (F / m), A = 0.75 in the above formula.
(M ² ): [When a magnetic recording medium with a width of 500 mm is wound around 180 ° around a main roller with a diameter of 1000 mm], V = 0.2, 1.0, 3.0 KV This is a graph of the power calculated.

When the protective layer 4 is actually formed, the magnetic recording medium
The lower limit of the adhesion force between the main roller 23 and the main roller 23 is slightly different depending on the applied voltage, but an electrostatic force of 2.5 to 3 KgW is required for a width of 500 mm, and as is clear from FIG. The film thickness of the dielectric film 23a is limited to about 0.5 mm.

Similarly, as is clear from FIG. 4, when the applied voltage is 3 KV, the film thickness of the dielectric film 23a is limited to 1.5 mm, but if the relative dielectric constant of 5 or more is selected, even if the film thickness of 3 mm or more is adhered. Power can be secured. However, in this case, current concentration is likely to occur because the applied voltage during film formation is high. Further, if the dielectric film 23a is made thicker, defects are more likely to occur at the time of coating the film, and the coating cost is significantly increased. Therefore, the upper limit of the thickness of the dielectric film 23a is about 3 mm.

As described above, according to this embodiment, when the protective film 4 is formed by the plasma CVD method as the vacuum film forming method, the dielectric film 23a is provided on the surface of the main roller 23 to form the substrate 1 By eliminating the concentration of penetrating current and enhancing the adhesion between the magnetic recording medium 20 and the main roller 23, the protective layer 4 with high adhesion strength and few defects can be formed over a long length while improving the deposition rate. It is possible, and it becomes industrially practical. Further, as the magnetic recording medium 20, not only dropout as a recording / reproducing defect and head clogging are reduced, but also the still life and the corrosion resistance are remarkably improved.

Subsequently, a second embodiment using a sputtering method as a vacuum film forming method for forming the protective layer 4 will be described with reference to FIG. 3 of the drawings.

The manufacturing apparatus of this embodiment shown in FIG. 3 differs from that of the apparatus of the first embodiment in that the plasma nozzle 26 for forming the protective layer is used for forming a film by a sputtering method as a vacuum film forming method. Instead, only the sputtering target 31 connected to the sputtering power source 32 is provided, and a metal, a carbide, a fluoride, or the like is used as the material for forming the protective layer. Since the other configurations are the same as those in the first embodiment, the corresponding components will be denoted by the same reference numerals, and detailed description will be omitted.

Hereinafter, the manufacturing method of this embodiment will be described together with the operation of the manufacturing apparatus.

The magnetic recording medium 20a on which the protective layer has not been formed has a feeding roller 21.
Is guided to the main roller 23 through the pass roller 22 and the bias power source 30 and the ferromagnetic metal thin film layer 2 and the main roller 23.
Voltage is applied between the main roller 23 and
The sheet is conveyed toward the pass roller 24 and the take-up roller 25 while closely adhering to. On the other hand, the protective layer forming sputtered molecules are released by the ions generated by the sputtering power source 32,
Magnetic recording medium 20 positioned corresponding to sputtering target 31
It collides with the ferromagnetic metal thin film layer 2 of a, and thereby the protective layer 4
Is formed. At this time, 0.01
By providing the dielectric film 23a of ~ 3 mm, the local current concentration is small and the current concentration penetrating the substrate 1 is completely eliminated, so that the voltage applied from the bias power source 30 to the main roller 23 can be increased. The film-forming speed is improved, the adhesion between the main roller 23 and the magnetic recording medium 20 is strengthened, the temperature rise of the substrate 1 is reduced due to the cooling effect, and the magnetic recording medium 20 is cut due to heat loss. Since there is nothing, it is possible to form the protective layer 4 having high adhesion strength and few defects. The magnetic recording medium 20 having the protective layer 4 thus formed passes through the pass roller 24 and the winding roller.
It is rolled up to 25.

As described above, according to the present embodiment, when the protective layer 4 is formed by using the sputtering method as the vacuum film forming method,
By providing the dielectric film 23a on the surface of the main roller 23, not only the same effect as in the first embodiment can be obtained, but also
There is an advantage that deterioration of the vacuum apparatus due to the reactive gas is not reduced and the sputtering method is used, so that a wide range of materials for forming the protective layer can be used.

Next, the details of the effects of each of the above-described embodiments are shown in Table-
This will be described with reference to FIGS. 1 and 4 and 5.

Table 1 shows the main rollers 13, 23 and the magnetic recording media 10, 20 for the plasma CVD method (1) and the sputtering method (2) in the first, second and conventional examples of the present invention. 9 is a table showing a processable length when the applied voltage between the ferromagnetic metal thin film layers 2 and the film formation rate are changed. According to the method of each embodiment of the present invention, the film formation rate is significantly improved. It can be understood that both the improvement of the processable length is compatible.

FIG. 5 shows two samples in the case where the protective layer 4 was formed at 30 m / min under the conditions of the applied voltage to the main roller 23 of -0.2 KV and -0.5 KV in the first embodiment, and as a representative of the conventional example, By the plasma CVD method, the applied voltage to the main roller 13
A sample having a protective layer 4 formed at 5 m / min at 0.1 KV was compared with a magnetic recording medium 10 or 20 provided with a lubricant layer 5 of stearic acid at a thickness of about 30 Å, and the still life and tension were set at 3 points. It was done. Compared with the conventional example, in the first embodiment of the present invention, an improvement of more than twice is recognized. this is,
This is because both the film quality and the adhesion strength of the protective layer 4 in the first embodiment are improved.

FIG. 6 is a diagram comparing the corrosion resistance of the magnetic recording media 10 and 20 manufactured under the same conditions as in FIG. 5 when left in an environment of a temperature of 60 ° C. and a humidity of 90%. Judging from the extent to which rust (corrosion) contaminates the head during running on a video tape recorder, the first embodiment shows an improvement of about three times that of the conventional example. It should be noted that the correlation between the degree of contamination of the head of the video tape recorder and the life of the magnetic recording media 10 and 20 has been confirmed in other experiments. This is because the voltage applied to the main rollers 13 and 23 rises, the substrate temperature stabilizes due to the improved adhesion, and so on, resulting in extremely stable film formation conditions, greatly reducing local current concentration, and reducing pinholes. Is reduced.

It goes without saying that dropout and head clogging as recording / reproducing defects are reduced. Also, regarding the still life and corrosion resistance, regarding the plasma CVD method,
Although explained with reference to FIGS. 6 and 6, substantially the same effect was confirmed in the sputtering method.

As described above, according to the present invention, when the ferromagnetic metal thin film of the magnetic recording medium is formed, the protective layer is continuously formed on the ferromagnetic metal thin film layer by the plasma CVD method or the sputtering method. By providing the dielectric film on the surface of the roller that closely conveys the magnetic recording medium in the processing area,
By reducing pinholes by reducing local current concentration, eliminating current concentration penetrating the substrate, and strengthening the adhesion with the roller, a protective layer with high adhesion strength and few defects can be obtained while improving the film deposition rate. Can be formed. As a magnetic recording medium, not only dropout and head clogging are reduced, but also improvement in still life and corrosion resistance are recognized.

In addition, the protective layer formed by the method of the present invention can be practically used as a magnetic recording medium with a sufficient margin, and can be industrially practically used because it can simultaneously improve the film formation rate and strengthen and stabilize the film quality. It is possible to realize this, and it will be a great advantage in production.

[Brief description of drawings]

FIG. 1 is a schematic view showing a manufacturing apparatus for forming a protective layer by a plasma CVD method as a first embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view of a main roller of the apparatus, Three
The drawing is a schematic view showing a manufacturing apparatus in the case of using the sputtering method as the second embodiment. FIG. 4 shows the adhesion strength of the substrate to the main roller, and FIG. 5 shows the magnetic recording medium prepared by the method of the first embodiment and the magnetic recording medium prepared by the method of the conventional example. The still life comparison chart, Fig. 6 shows the fifth chart.
FIG. 7 is a comparative diagram of the corrosion resistance of each magnetic recording medium prepared in the same manner as FIG. 7, FIG. 7 is a sectional view showing the structure of the magnetic recording medium,
FIG. 8 is a diagram showing a conventional apparatus for manufacturing a magnetic recording medium by the plasma CVD method. 20 ... Magnetic recording medium, 20a ... Magnetic recording medium before protective layer formation 20b ... Magnetic recording medium with protective layer formation, 22,24 ... Pass roller 23 ... Main roller, 23a .. Dielectric film 26 ... Protection Layer forming plasma nozzle 27 …… Plasma generating electrode, 28 …… Gas inlet, 29 ……
Plasma generation power supply, 30 …… Bias power supply 31 …… Sputtering target, 32 …… Sputtering power supply

Claims (4)

(57) [Claims] 1. A magnetic recording medium having a ferromagnetic metal thin film layer formed on a non-magnetic substrate is transported while being supported by a plurality of rollers, and power is supplied to the ferromagnetic metal thin film layer through one of the rollers. In the method of continuously forming a protective layer on the ferromagnetic metal thin film layer by a vacuum film formation method, the surface of the ferromagnetic metal thin film layer is 0.01 to 3 mm and the relative dielectric constant is 2 or more. A method for manufacturing a magnetic recording medium, characterized in that a protective layer is formed by a film formation method in a vacuum while supplying power through a roller provided with a dielectric film. 2. A magnetic recording medium having a ferromagnetic metal thin film layer formed on a non-magnetic substrate is transported while being supported by a plurality of rollers, and power is supplied to the ferromagnetic metal thin film layer through one of the rollers. In the method of continuously forming a protective layer on the ferromagnetic metal thin film layer by a vacuum film formation method, the surface of the ferromagnetic metal thin film layer is 0.01 to 3 mm and the relative dielectric constant is 2 or more. A method for manufacturing a magnetic recording medium, which comprises forming a protective layer by a plasma CVD method while supplying power through a roller provided with a dielectric film. 3. A magnetic recording medium having a ferromagnetic metal thin film layer formed on a non-magnetic substrate is transported while being supported by a plurality of rollers, and power is supplied to the ferromagnetic metal thin film layer via one of the rollers. In the method of continuously forming a protective layer on the ferromagnetic metal thin film layer by a vacuum film formation method, the surface of the ferromagnetic metal thin film layer is 0.01 to 3 mm and the relative dielectric constant is 2 or more. A method of manufacturing a magnetic recording medium, characterized in that a protective layer is formed by a sputtering method while feeding power through a roller provided with a dielectric film. 4. A plurality of rollers for transferring a magnetic recording medium having a ferromagnetic metal thin film layer formed on a non-magnetic substrate in a certain direction, and a vacuum provided so as to correspond to one of these rollers. A processing device for forming a protective layer on the ferromagnetic metal thin film layer by a film forming method, and for supplying power to the roller to supply power to the ferromagnetic metal thin film layer through a roller corresponding to the processing device. In a magnetic recording medium manufacturing apparatus equipped with a power source, a dielectric film having a thickness of 0.01 to 3 mm and a relative permittivity of 2 or more is provided on the surface of a roller which is fed at a position corresponding to the processing apparatus. An apparatus for producing a characteristic magnetic recording medium.