JPH0221052B2 - - 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 of a ferromagnetic metal is continuously formed on a long polymer film by an ion plating method.

In recent years, with the aim of dramatically increasing recording density, magnetic recording media such as magnetic tape, which does not use a resin binder and has a ferromagnetic metal thin film as a magnetic recording layer on a non-magnetic base material, have been developed using vacuum evaporation methods and sputtering methods. ,
Vigorous research and development has been conducted using thin film formation methods such as ion plating and cluster ion beam methods, and some of them have even reached the point of being put into practical use.

In particular, magnetic recording media formed by the ion plating method performed in a high vacuum with a degree of vacuum of the order of 10 ^-4 Torr or lower (for example, magnetic recording by the method proposed in Japanese Patent Application No. 55-30807) The medium) has good magnetic performance, high density strength with the base material, and excellent wear resistance of the magnetic layer, making it suitable for the method of manufacturing magnetic recording media such as magnetic tapes.

At the same time, the ion plating method
The following problems have been encountered in manufacturing long magnetic recording media on an industrial scale.

That is, since this method forms a magnetic layer by continuously injecting high-energy ions onto the surface of a polymer film such as polyethylene terephthalate, which is a dielectric material, When the film base material runs in contact with metal bodies such as film cooling drums, cooling plates, accelerating electrodes, and guide rolls, electrostatic adsorption occurs, resulting in excessive film tension. This has the problem of causing wrinkles on the film, and if the wrinkles are severe, it becomes difficult to run the film.

Furthermore, as a result of the non-uniform running of the film due to the electrostatic adsorption phenomenon, there is a problem in that the film is thermally deformed by the action of the latent heat of vaporization of the deposited material and the radiant heat from the evaporation source.

The present invention reduces the film tension by alleviating the electrostatic adsorption phenomenon described above, thereby stably and continuously forming a magnetic layer on a long polymer film without causing wrinkles or thermal deformation of the film. An object of the present invention is to provide an industrially superior method for manufacturing a magnetic recording medium that can be formed by an ion plating method. That is, the gist of the present invention is to continuously run a long polymer film in a high vacuum, and to inject evaporated particles of ferromagnetic metal containing ions accelerated by an electric field onto the surface of the film. When forming the magnetic layer, the formed magnetic layer is brought into contact with a metal body that is applied to approximately the same potential as an accelerating electrode that is provided for electric field acceleration of ions and that the polymer film runs in contact with. A method of manufacturing a magnetic recording medium is provided.

The polymer film in the present invention is made from polymer materials such as polyvinyl chloride, polyvinyl fluoride, cellulose acetate, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polycarbonate, polyimide, polyether sulfon, polyparabanic acid, etc. A long film made of polyethylene terephthalate is particularly preferably used.

Further, the thickness of the polymer film is not particularly limited, but a thickness in the range of 3μ to 20μ is usually used.

In the present invention, an ion plating method is employed to form a magnetic layer on the surface of the polymer film, and a high vacuum ion plating method, which is performed without using plasma, is particularly suitable.

The above-mentioned high vacuum ion plating method is a method proposed in Japanese Patent Application No. 55-30807.
A ferromagnetic metal material is supplied to an open crucible in a vacuum chamber evacuated to a high vacuum level of 10 ^-4 Torr or less, and then subjected to resistance heating, electron beam heating, electron bombardment heating, and induction heating. heating the metal material to vaporize it, then accelerating electrons emitted from an electron radiation source with an electric field and colliding with the vapor particles to ionize them,
Furthermore, the ionized vapor particles are accelerated by an electric field effect, imparting high energy of about 1ev to 10Kev, and collided with the surface of the substrate to form a thin film.

The ferromagnetic metals used in the present invention include iron,
Examples include single metals such as nickel and cobalt, and alloys or mixtures containing one or more metals selected from the group of iron, nickel, and cobalt. Iron alloys include iron and cobalt, nickel, manganese, chromium, copper, gold, and titanium, and cobalt alloys include cobalt and phosphorus.
Chromium, copper, nickel, manganese, gold, titanium,
Examples of alloys with yttrium, samarium, bismuth, etc. and alloys with nickel include alloys with nickel, copper, zinc, manganese, etc.;
As a mixture of iron, cobalt, nickel and other elements, the other elements may be phosphorus, chromium, copper, zinc,
Examples include mixtures of one or more of gold, titanium, yttrium, samarium, bismuth, and the like.

Next, the method for manufacturing a magnetic recording medium according to the present invention will be explained in more detail.

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention.

The inside of the vacuum chamber 1 is brought to a high vacuum of up to 1×10 ^-7 Torr by an exhaust system device (consisting of an oil rotor, a pump, an oil diffusion pump, etc., not shown) connected to an exhaust port 2. It is designed so that it can be exhausted.

Inside the vacuum chamber 1 are an ion source 3, a polymer film 4, a supply roll 5 for the film, a take-up roll 6, guide rolls 7, 8, steam shielding plates 9, 10,
11. Ion accelerating electrode/film cooling plate 12,1
3. A metal roll 14 and a rubber pinch roll 15 that are applied with approximately the same potential as the accelerating electrodes 12 and 13.
is located.

Further, a DC power supply 16 for applying a negative high potential to the accelerating electrodes 12, 13 and the metal roll 14 is installed outside the vacuum chamber.

FIG. 2 is a schematic diagram showing the structure of the ion source 3 in FIG. 1.

In FIG. 2, 40 is an electron beam evaporation source, which consists of a 180° eccentric E gun 43, a water-cooled copper hearth 44, and an evaporation source material 45 (however, the power supply etc. are not shown). 46 is a baffle plate for steam shielding, and the steam flow 47 that has advanced as shown in the figure is ionized in an ionization section 48. The ionization section 48 is composed of a filament 49 for emitting thermionic electrons, a mesh electrode 50 for accelerating electrons with an electric field, and a guard 53 for controlling the electric field.

In the ion source 3, the evaporation source material 45 is heated and evaporated by the E gun 43, and the filament 49 is electrically heated by the power supplies 54 and 55 disposed outside the vacuum chamber 4 to emit thermoelectrons, and a negative DC voltage is applied. is applied to accelerate the electrons in an electric field, thereby ionizing the vapor particles.

Next, to manufacture the magnetic recording medium, a long polymer film 4 is set as shown in FIG ^.
A high vacuum of less than Torr is created, and the ion source 3 is started to vaporize the ferromagnetic metal supplied to the electron beam evaporation source 40, and a part of the vapor is transferred to the ionization section 48.
A negative potential for accelerating the ions is applied to the ion accelerating electrodes and film cooling plates 12 and 13, and the polymer film 4 is ionized and released by driving the supply roll 5, take-up roll 6, etc. By running the film 4 at a constant speed while being in contact with the ion accelerating electrode/cooling plates 12 and 13, evaporated particles of ferromagnetic metal containing ions accelerated by an electric field are incident thereon to form a magnetic layer on the surface of the film 4. However, in the present invention, film 4
In the embodiment shown in FIG. 1, a metal roll 14 is used, which is placed in contact with the magnetic layer formed on the surface of the accelerating electrode/cooling plate. A negative voltage of approximately the same potential as that applied to 12 and 13 is applied.

The point at which the metal body comes into contact with the magnetic layer on the film surface may be after the magnetic layer has been formed as a continuous layer on the film surface, even during vapor deposition, or immediately after vapor deposition. It's okay to be hot.

In the present invention, as described above, a metal body is used so as to be in contact with the magnetic layer formed on the film surface, and since the metal body is applied to approximately the same potential as the accelerating electrode, This prevents the film from being electrostatically attracted to the accelerating electrode that it runs in contact with, making it possible to produce a magnetic recording medium with excellent performance without wrinkles or thermal deformation of the film.

Examples of the present invention will be described below.

Example A supply roll 5 wound with polyethylene terephthalate film having a thickness of 15μ and a width of 500mm was set, and as shown in FIG. 1, a guide roll 7, a cooling plate 12, a metal roll 14, a cooling plate 13, and a guide roll 8 The film was arranged so as to be wound up on a winding roll 6 through the winding process. Electron beam evaporation source 40 of ion source 3
Supplied 200g of cobalt metal ingot (99.5% purity) to
The minimum angle of incidence of the ion beam from the ion source 3 onto the film surface (the angle with the film surface normal) is
The ion source 3 and the shielding plates 9, 10 are aligned at an angle of 60°.
We made adjustments to the placement of the

Next, after evacuating the inside of the vacuum chamber 1 to 1 x 10 ^-6 Torr, the roll drive system (consisting of a motor, gears, etc., not shown) is operated so that the film feeding speed becomes 50/min. did. At this time, the sliding resistance between the cooling plate 12 and the film 4, which was obtained by measuring the torque applied to the metal roll 14, was about 700 g.

Next, the ion source 3 was operated, and a beam consisting of cobalt neutral vapor and cobalt ions was incident on the film surface to start vapor deposition. At this time, -100V is applied to the cooling plates 12 and 13 by the power supply 16.
When the film tension was measured when a DC voltage was applied and the film was deposited without applying the DC voltage to the metal roll 14, it reached 50 kg or more and the cooling plate 1
2. Numerous vertical wrinkles appeared between the metal rolls 4 and between the cooling plate 13 and the guide roll 8, and the wrinkles caused uneven deposition, and the film broke after 5 minutes.

Next, in the same manner as above, the metal roll 14 is
When vapor deposition was performed by applying a DC voltage of 1000 V, the film tension stabilized at 4.0 kg, and no wrinkles or thermal deformation were observed. Regarding the obtained magnetic recording medium, the adhesion strength between the base material and the magnetic layer, and between the magnetic layer and the protective layer was examined by a peel test using a cellophane tape, and no peeling occurred at all.

Furthermore, using a commercially available oven-reel type tape recorder, an abrasion test was conducted on the ferromagnetic thin film layer of the magnetic recording medium, which was made into an endless tape, at a running speed of 9.5 cm/sec and in the playback state.
Even after repeated playback 100 times, no clear wear marks were observed with the naked eye.

Furthermore, as a result of measuring the magnetic properties of the magnetic recording medium using a DC magnetization measuring device, the coercive force was 700.
Oersted residual magnetic velocity density 9000 Gauss, squareness ratio
0.90, and a magnetic recording medium with high coercive force and high squareness ratio required for high-density recording was obtained.

[Brief explanation of drawings]

FIG. 1 is a model diagram showing an example of an apparatus used in the present invention, and FIG. 2 is a model diagram showing the structure of the ion source 3 shown in FIG. 1. 1... Vacuum chamber, 2... Exhaust port, 3... Ion source, 4...
Polymer film, 5... Supply roll, 6... Winding roll, 7, 8... Guide roll, 9, 10, 11...
Steam shielding plate, 12, 13... Ion accelerating electrode and film cooling plate, 14... Metal roll, 15... Pinch roll, 16... Electrode, 40... Electron beam evaporation source, 4
7... Steam flow, 48... Ionization section.

Claims (1)

[Claims] 1. While a long polymer film is continuously running in a high vacuum, evaporated particles of ferromagnetic metal containing ions accelerated by an electric field are incident on the surface of the film. When forming the magnetic layer, the formed magnetic layer is brought into contact with a metal body that is applied to approximately the same potential as an accelerating electrode that is provided for electric field acceleration of ions and that the polymer film runs in contact with. A method of manufacturing a magnetic recording medium characterized by: 2. The manufacturing method according to item 1, wherein the metal body is a guide roll for holding and guiding the polymer film on which the magnetic layer is formed.