JPH0120490B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a magnetic recording medium using a ferromagnetic metal thin film layer as a magnetic recording layer. Conventionally, magnetic recording media have been widely used in which acicular magnetic powder such as iron oxide or chromium oxide or ultrafine powder of ferromagnetic metal is dispersed in a resin binder and coated on a non-magnetic base material. has been used. However, in recent years, as a result of the strong demand for high-density recording of information on magnetic recording media,
Various improvements have been made, but in the conventional coating-type magnetic recording media described above, there is a limit to the size of the ferromagnetic powder particles used as the smallest unit of the recording element, and it is necessary to increase the recording density beyond that limit. Since this is theoretically impossible, it was difficult to meet the request for high-density recording. For this reason, recently, with the aim of dramatically increasing recording density, magnetic recording media that do not use a resin binder and have a ferromagnetic metal thin film layer as a magnetic recording layer have been developed using wet plating methods, vacuum evaporation methods, sputtering methods, ion plating methods, etc. Research and development has been carried out vigorously using thin film formation methods such as the Teing method, and some of them have been put into practical use. However, the ferromagnetic metal thin film layer has a fatal defect as a recording storage medium in that it is easily oxidized even under normal storage conditions, and its magnetic performance deteriorates over time. In addition, even if the surface is touched with fingers, the portion will rapidly corrode, and furthermore, during recording and reproduction, the magnetic layer is likely to peel off, wear out, be damaged, fall off, etc. due to contact scanning with the head. There was a drawback. In order to improve the above drawbacks, various proposals have been made to provide various protective layers on the surface of the ferromagnetic metal thin film. For example, a polymer film can be formed by a solution coating method, a metal film can be formed by a wet plating method such as electrolytic plating or electroless plating method, or a metal film can be formed by a chromic acid treatment using an aqueous solution such as chromic acid. Although many methods have been proposed, such as forming a reaction film or forming an oxide film on the surface of a ferromagnetic metal thin film by heating the recording medium at high temperature in an oxidizing atmosphere, there is still no sufficient protective layer. However, the method for forming the same has many problems that need to be solved. That is, the method of forming a polymer film by coating requires a coating process, requires large-scale incidental equipment for solvent recovery or pollution prevention, and also requires sufficient corrosion resistance. This requires a film thickness of several microns or more, which has the disadvantage of lowering the recording density. Furthermore, the method of forming a film by chromic acid treatment has the same drawbacks as above in wastewater treatment due to the toxicity of hexavalent chromium.
In the method of forming a corrosion-resistant metal coating by wet plating, the resulting coating has low wear resistance and is easily damaged. Attempts have been made to form the above-mentioned corrosion-resistant metal coating by vacuum evaporation, but this method has the drawback of insufficient wear resistance. Furthermore, in the method of forming an oxide film by subjecting the recording medium to high temperature heat treatment in an oxidizing atmosphere, recording media whose base material is a polymeric material such as polyethylene terephthalate,
It has the disadvantage that it undergoes thermal deformation, and the ferromagnetic metal thin film itself also undergoes a change in crystal structure and other properties due to heat treatment, resulting in changes in its magnetic properties. An object of the present invention is to eliminate the above-mentioned drawbacks and provide a method for manufacturing a magnetic recording medium that is excellent in wear resistance, corrosion resistance, and magnetic properties. B, C,
Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni,
It is characterized by imparting kinetic energy in the range of 10eV to 15KeV to ions of an element selected from the group of Cu, Ag, Mo, Au, and Sm, and making them incident together with neutral evaporated particles of the material forming the protective layer. A method of manufacturing a magnetic recording medium is provided. In the present invention, conventionally known vapor deposition methods such as vacuum vapor deposition, sputtering, ion plating, and cluster ion beam methods are employed to provide a ferromagnetic metal thin film on a base material made of nonmagnetic material by vapor deposition. However, in order to increase the adhesion strength with the base material and maintain good magnetic properties,
Particularly preferred is the ion plating method or the cluster ion beam method, which is carried out under a high vacuum at a pressure lower than 10 ^-4 torr. The base material made of non-magnetic material used in the present invention includes polyvinyl chloride, polyvinyl fluoride, cellulose acetate, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polycarbonate, polyimide, polyether sulfon, Polymer materials such as polyvalabanic acid, non-magnetic metal materials such as aluminum, copper, and copper-zinc alloys, ceramic materials such as sintered materials, porcelain, earthenware, and glass are used. In the present invention, the shape of the base material made of the non-magnetic material may be appropriately determined depending on the usage method of the magnetic recording medium, and for example, it may be a tape, a film, a
Used in the form of disks, drums, etc. Examples of the ferromagnetic metal in the present invention include single metals such as iron, 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,
Alloys with copper, nickel, manganese, gold, titanium, yttrium, samarium, bismuth, etc.; Alloys of nickel include alloys with nickel, copper, zinc, manganese, etc.; As a mixture with other elements,
Examples include mixtures in which the other element is one or more of phosphorus, chromium, copper, zinc, gold, titanium, yttrium, samarium, bismuth, and the like. As the ferromagnetic metal, it is preferable to use cobalt or a ferromagnetic material containing cobalt. Also, the thickness of the ferromagnetic metal thin film layer to be formed is
The range of 200 Å to 50000 Å is preferable, more preferably
It ranges from 500 Å to 5000 Å. In the present invention, a protective layer is formed on the magnetic thin film made of the above-mentioned ferromagnetic metal, and materials for forming the protective layer include noble metals such as platinum and gold, and passive materials such as aluminum, nickel, and chromium. metals, aluminum, silicon, chromium,
Oxides and nitrides such as titanium are used, and to form the protective layer, neutral evaporated particles obtained by evaporating these protective layer forming materials under vacuum conditions are deposited on the magnetic thin film. It will be done. In the present invention, in addition to the neutral evaporated particles of the protective layer forming material, B (boron), C (carbon), Si (silicon), P (phosphorus), Ti (titanium), V
(vanadium), Cr (chromium), Mn (manganese), Fe
(iron), Co (cobalt), Ni (nickel), Cu (copper),
High-speed ions of an element selected from the group consisting of Ag (silver), Mo (molybdenum), Au (gold), and Sm (samarium) are charged with kinetic energy in the range of 10 eV to 15 KeV onto the magnetic thin film. A protective layer is formed by allowing the light to enter the room. By forming a protective layer on the surface of the ferromagnetic metal thin film as described above, it is possible to obtain a magnetic recording medium which not only has excellent wear resistance and corrosion resistance, but also has excellent basic magnetic properties, particularly coercive force. At present, it is not clear how the irradiation of high-velocity ions of the above-mentioned specific elements will affect the fine structure of the ferromagnetic metal thin film and the protective layer during the formation of the protective layer, but the ion implantation effect and continuous ion bombardment during vapor deposition may affect the deposited film. It is thought that the fine structure suitable for a magnetic recording medium was brought about by the influence of nucleation on nucleation and film growth, the migration effect on the surface of the deposited object, etc. Next, the present invention will be explained in more detail using the drawings. FIG. 1 is a diagram showing an example of a method for manufacturing a magnetic recording medium according to the present invention. The inside of the vacuum chamber 1 is heated to 10 ^-7 torr by a non-gas system device (consisting of an oil rotary pump, an oil diffusion pump, etc., not shown) connected to the exhaust port 2.
It is designed so that it can be evacuated to high vacuum levels. Inside the vacuum chamber 1, there is an electron beam evaporation source 3 supplied with the main material for forming the protective layer by vapor deposition, a vapor shielding plate 4, an ion source 5 for irradiating accelerated ions of a specific element, and a negative evaporation source 3 for accelerating the ions. An accelerating electrode 6 to which a DC high voltage is applied and its power source 7, a film 8 on which a ferromagnetic metal thin film is deposited, a supply roll 9 for the film, a take-up roll 10, and guide rolls 11 and 12 are arranged. . However, the power supply circuit for operating the electron beam evaporation source 3 and the ion source 5 and the roll drive system required for running the film 8 are not shown. Electron beam evaporation source 3 is 180
It is composed of a deflection E gun 13, a crucible 14, and a material 15 for forming a protective layer. FIG. 2 is a cross-sectional view showing the configuration of the ion source 5, which consists of an evaporation source section 15 for generating atomic particles with uniform directionality and an ionization section 16 for ionizing the evaporated particles. ing. The evaporation source part 15 is a heater crucible 1 that is heated by electricity.
7. It consists of an electrode 19 with a water cooling jacket 18 and an evaporation material 20 fed into the crucible 17. The evaporation source section 15 is operated by applying a low voltage AC power source 21 installed outside the vacuum chamber 1. The ionization unit 16 includes a filament 22 for emitting thermionic electrons, a mesh electrode 23 for accelerating the emitted electrons with an electric field, and a guard 24 for controlling the electric field.
It is made up of. The operation of the ionization section 16 is performed by the filament 22 by the low voltage AC power supply 25.
is heated to emit thermoelectrons, and the electrons are accelerated by an electric field formed by applying a negative potential to the filament 22 by the DC high-voltage power supply 26 and grounding the mesh electrode 23, and generated in the evaporation source section 15. This is done by colliding with vapor particles and ionizing them. Next, an example of a method for manufacturing a magnetic recording medium according to the present invention will be described. First, cobalt is evaporated under a vacuum condition higher than 10 ^-5 Torr, and the evaporated particles are bombarded with accelerated electrons. Using the high-vacuum ion plating method, in which the ionized particles are accelerated by an electric field and made incident on the substrate surface, a vapor deposition tape with a 1500 Å thin cobalt film layer on a 15 μ thick polyethylene terephthalate film is created. This is prepared as a film 8 and wound onto the supply roll 9 shown in FIG. 1, and set as shown in the same figure. Next, the material for forming the protective layer is placed in crucible 1.
4, and an evaporation material made of an element selected from the group specified in the present invention is supplied to the heater crucible 17 shown in FIG. 2 of the ion source 5, and each is arranged as shown in FIG. do. Next, the inside of the vacuum chamber 1 is pumped 8× using the exhaust system device from the exhaust port 2.
Evacuate to high vacuum in the range of 10 ^-4 Torr to 10 ^-8 Torr. When the degree of vacuum is stabilized, the ion source 5, evaporation source 3, and accelerating electrode 6 are operated while the film 8 is traveling in the direction from the guide rolls 11 to 12.
An evaporation source 3 is placed on the ferromagnetic metal magnetic thin film of the film 8.
It is generated from the ion source 5 along with neutral evaporated particles generated from the
A protective layer is formed by injecting ions of a specific element that have been accelerated to have a kinetic energy in the range of . In the illustrated embodiment, the ion source 5 is located approximately in front of the surface of the film 8, and the evaporation source 3 is located obliquely to the surface of the film 8. However, the present invention is not limited to this, and the angle at which the ion source 5 and the evaporation source 3 are arranged with respect to the surface of the film 8 can be freely selected. Thus, the magnetic recording medium obtained according to the present invention has improved abrasion resistance among the protective layer functions, and especially improved coercive force among the basic magnetic properties, compared to one in which a protective layer is simply formed by vapor deposition. This results in a magnetic recording medium with improved properties. Examples and comparative examples of the present invention will be described below. Example While running a polyethylene terephthalate tape with a thickness of 15μ at a constant speed, cobalt evaporation particles ionized by accelerated electron collisions were applied to the tape surface under electric field acceleration in a high vacuum of 5×10 ^-6 Torr. A vapor deposition tape having a cobalt vapor deposition layer with a thickness of 1500 Å was prepared by making the light incident on the cobalt film. A protective layer with a thickness of about 500 Å was formed on the vapor-deposited tape using the apparatus shown in FIG. The types of neutral evaporation particles and ions used at that time were
The table shows the conditions for ion deposition: ion kinetic energy: 1KeV, ion current:
It was set to 150μA. The thus obtained magnetic tape was tested for coercive force, corrosion resistance, and abrasion resistance, and the results shown in Table 1 were obtained. In addition, for comparison, the vapor deposition tape prepared above without any protective layer (Comparative Example 1) and the vapor deposition tape prepared above were coated with approximately 500 Å by operating only the electron beam evaporation source 3 of the apparatus shown in FIG. The above test results are also listed in Table 1 for the product with a chromium vapor deposited layer (Comparative Example 2).

[Table] However, coercive force is measured by a DC magnetization measuring device (BH curve tracer), and corrosion resistance is evaluated by the presence or absence of corrosion when left for 250 hours at a temperature of 60°C and a relative humidity of 100%. In addition, wear resistance is determined by whether or not there are any peeling points in a peel test with Sellotape, and whether scratches remain in a test using a Sapphire ball (diameter 0.1 mm) under a load of 30 g. and evaluated by the rate of decrease in playback output after passing an endless tape sample through the head of a commercially available cassette tape recorder 1000 times.
Displaying these results.

[Brief explanation of drawings]

FIG. 1 is a mode diagram showing one example of the method of the present invention, and FIG.
The figure is a cross-sectional view of the ion source 5 of FIG. 1. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 3... Electron beam evaporation source, 5... Ion source, 6... Accelerating electrode, 8... Film, 15... Evaporation source part, 16... Ionization part.

Claims (1)

[Scope of Claims] 1. A magnetic thin film made of a ferromagnetic metal provided by a vapor deposition method on a base material made of a nonmagnetic material, containing B,
C, Al, Si, P, Ti, V, Cr, Mn, Fe, Co,
Imparting kinetic energy in the range of 10 eV to 15 KeV to ions of an element selected from the group of Ni, Cu, Ag, Mo, Au, and Sm, and making them incident together with neutral evaporated particles of the material forming the protective layer. A method of manufacturing a magnetic recording medium characterized by: 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the ferromagnetic metal is Co or a ferromagnetic material containing Co.