JPS6151336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing a magnetic recording medium in which a magnetic layer having uniform magnetic properties is formed in the width direction of a base material.

Conventionally, magnetic recording media have been made by dispersing acicular magnetic powder such as iron oxide or chromium oxide or ultrafine powder of ferromagnetic metal in a resin binder and coating this on a non-magnetic base material. has been widely used.

However, in recent years, there has been a 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 mentioned above, the particle size of the ferromagnetic powder used has reached its limit as the smallest unit of the recording element, and it is necessary to further increase the recording density. Since this is impossible in principle, it has been difficult to meet the demand for higher density recording.

For this reason, recently, with the aim of dramatically increasing recording density, magnetic layers that do not use resin binders have been developed.
Thin-film (vapor-deposited) magnetic recording media made of 100% ferromagnetic material have been actively researched and developed using thin-film formation methods such as wet plating, vacuum evaporation, sputtering, and ion plating. is in practical use.

However, the magnetic recording media obtained by each of the above-mentioned thin film forming methods have their own drawbacks and have various practical problems.

In other words, thin-film magnetic recording media formed by wet plating or vacuum evaporation have extremely low adhesion strength between the magnetic layer and the base material. The disadvantage is that the magnetic layer is likely to peel off due to friction, or be easily damaged by friction.

In addition, thin film magnetic recording media formed by sputtering method or ion plating method are
Although the adhesion strength between the magnetic layer and the base material is improved,
Since this method uses DC glow discharge or high-frequency plasma in a low vacuum of 10 ^-3 Torr or more to form a thin film, the crystals of the ferromagnetic thin film layer may deteriorate due to the incorporation of residual gas or the mixing of impurities. The smaller the squareness ratio, the more disadvantageous the magnetic properties were. Furthermore, it has drawbacks such as variations and non-uniformity in film quality and magnetic properties due to non-uniformity of the discharge state, and these problems still need to be solved as a magnetic recording medium for high-performance, high-density recording. I left a lot of.

In addition, when manufacturing thin-film magnetic recording media by ion plating or the like, it is important to form a magnetic layer on a wide long film substrate by vapor deposition, and then cut it to the desired width, in terms of manufacturing efficiency. is preferable, but
Conventionally, it has been difficult to form a ferromagnetic thin film layer having uniform magnetic properties in the width direction of a wide film.

In view of the current state of manufacturing methods for conventional thin-film magnetic recording media as described above, the present invention has developed a wide ferromagnetic thin-film layer that has magnetic properties suitable for high-density recording and has excellent practical properties such as wear resistance. The purpose of this invention is to provide a method and apparatus for manufacturing a magnetic recording medium that can be deposited uniformly on a base material, particularly in a manner that the magnetic properties are uniform in the width direction. heats a closed crucible with a long slit under high vacuum,
The ferromagnetic metal supplied into the crucible is vaporized and ejected from the slit of the crucible to generate a band-shaped vapor flow, and by irradiating the band-shaped vapor flow with accelerated electrons, the vapor in the vapor flow is It is characterized by ionizing the particles and accelerating the ionized vapor particles in an electric field so that they are incident on the entire width direction of the surface of a long film-like base material to form a thin film layer of ferromagnetic metal on the surface of the base material. A method for producing a magnetic recording medium and a width of a long film-like base material in which a thin film layer of ferromagnetic metal is to be formed in a vacuum chamber that can be evacuated to a high vacuum of 8×10 ^-4 Torr or less A closed crucible having a long slit for steam ejection, the depth of which is greater than the gap between the slits, a heating means for the crucible, a filament for emitting thermionic electrons, and a plate-shaped electrode for accelerating electrons. An accelerated electron irradiation device comprising an accelerated electron irradiation device, a substrate transfer device for moving a long film-like substrate, and ionization in which ferromagnetic metal vapor particles are ionized by accelerated electron irradiation by the accelerated electron irradiation device. An apparatus for manufacturing a magnetic recording medium is characterized in that it is provided with an electrode for accelerating vapor particles with an electric field.

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

FIG. 1 is a schematic diagram showing an example of an apparatus used in the method of manufacturing a magnetic recording medium of the present invention, and these apparatuses are placed in a vacuum chamber (not shown) that can be evacuated to a high vacuum. has been done. Here, the high vacuum referred to in the present invention means a vacuum state with a degree of vacuum higher than 1×10 ^-3 Torr, and usually a vacuum degree of 8×10 ^-4 to 1×10 ¹⁰ Torr may be adopted. .

In the figure, 1 is a closed crucible having a long slit, and a ferromagnetic metal 11 is supplied into the crucible 1. As the ferromagnetic metal 11, single metals such as iron, nickel, and cobalt, and alloys or mixtures of these metals with other metals can be used.

Further, 2 is a filament for emitting thermionic electrons, and 3 is an electrode for accelerating electrons, and the filament 2 and the electrode 3 constitute an accelerated electron irradiation device.

Further, 4 is a wide long film-like base material,
The base material 4 is continuously transported in the direction indicated by the arrow in the longitudinal direction of the base material 4 by a base material transfer device composed of a supply roll 5, guide rolls 6 and 7, and a take-up roll 8. is being done. However, driving devices for these rolls 5, 8, etc. are not shown. As the material for the base material 4, any non-magnetic material that can be formed into a flexible film-like material can be used, but organic polymeric materials such as polyethylene terephthalate are preferably used. or,
Reference numeral 9 denotes an electrode for accelerating ionized vapor particles with an electric field, and the electrode 9 has the function of accelerating the ionized vapor particles with an electric field, and also has the function of supporting the base material 4 from the back side.

FIG. 2 is a partially cutaway view showing the crucible 1 in FIG. W indicates the width of the slit opening, and D indicates the depth of the slit.

The depth D of the slit means the shortest distance between the crucible inner open end _D1 and the outer open end _D2 of the slit opened at the top of the closed crucible.

Therefore, in the present invention, a crucible 1 having a long slit in which the length L of the slit is longer than the width of the base material 4 used is used, and the depth of the slit of the crucible 1 is usually The dimension D is larger than the width W of the slit, and
It is preferable that the mean free path of the vapor particles in the crucible 1 be larger than the mean free path of the vapor particles in the crucible 1 in order to make the vapor flow of the ferromagnetic metal vapor particles ejected from the slit into a band-shaped vapor flow with directionality. .

Further, the materials constituting the crucible 1 include graphite, boron nitride, alumina, magnesia,
Beryllium, zirconia, etc. are preferably used.

Next, in order to manufacture a magnetic recording medium by the method of the present invention, the ferromagnetic metal 11 to be deposited is supplied to the crucible 1 of the apparatus shown in FIG. 4. Set on roll 8 etc. for winding, and keep the vacuum chamber under high vacuum, preferably at an atmospheric pressure of 8×
Evacuate to maintain a high vacuum of 10 ^-4 Torr or less,
The crucible 1 is heated under high vacuum to vaporize the ferromagnetic metal 11. The heating is performed by a crucible heating means (not shown), and means such as ordinary heating, induction heating, and electronic bombardment heating are preferably employed as the heating means.

The vapor of the heated and vaporized metal 11 is ejected from the slit of the crucible 1 and becomes a vapor flow,
The vapor flow becomes a band-shaped vapor flow having a width corresponding to the slit size of the crucible 1.

In the accelerated electron irradiation device, an alternating current is applied to the conducting wires 21 and 22 connected to both ends of the filament 2 for emitting thermionic electrons to heat the filament 2, thereby emitting thermionic electrons.
By applying a negative DC voltage of 100 V to 800 V and grounding the electron acceleration electrode 3 through a conductive wire 31, the emitted thermoelectrons are accelerated by an electric field.

The band-shaped vapor stream ejected from the slit of the crucible 1 reaches the accelerated electron irradiation device, where the vapor particles collide with thermionic electrons accelerated by the electric field and are ionized. The electron current emitted from the filament 2 for ionization at this time is preferably in the range of 10 mA to 500 mA.

The vapor particles constituting the ionized band-shaped vapor flow are given high kinetic energy and accelerated by an electric field by applying a negative DC voltage of -100V to -10KV to the electrode 9 placed in front of them through the conductor 91. As a result, it is uniformly incident on the entire width of the surface of the base material 4, and is deposited on the surface of the base material 4 together with non-ionized neutral metal vapor to form a thin ferromagnetic film. In addition,
Generally, the base material 4 is transported at a constant speed in conjunction with the above operation, but it is also possible to transport the base material 4 intermittently over a constant width if necessary.

In addition, the positional relationship between the crucible 1 and the base material 4 in the present invention is such that the ionized band-shaped vapor flow is uniformly incident on the entire surface of the base material 4 in the width direction.
It is only necessary to arrange the long slits so that the longitudinal direction of the long slits and the longitudinal direction of the base material 4 are substantially perpendicular to each other, and as shown in FIG. By making the incidence oblique, it is possible to obtain a recording medium with particularly excellent magnetic properties such as squareness ratio.

The present invention is a manufacturing method as described above, in which a closed crucible having a long slit is used, and the crucible generates a band-shaped vapor flow with well-aligned ionized directions on the surface of the base material. Since the light is incident over the entire width direction, the formed thin film has good crystallinity and is uniform in the width direction of the base material, making it possible to make a recording medium formed using a wide long film as a base material even smaller. Even when cut into wide tapes, there is little variation in quality among the resulting tape-shaped recording media, and therefore, according to the present invention, vapor recording media can be efficiently produced.

Furthermore, in the present invention, a method is adopted in which vapor particles are ionized in a high vacuum, accelerated by an electric field, and made to impinge on the substrate surface. Problems such as performance deterioration, quality variations, and non-uniformity in steam characteristics caused by contamination of impurities and non-uniform discharge conditions have been resolved, and the product has steam characteristics suitable for high-density recording, as well as wear resistance. It is therefore possible to manufacture a recording medium with excellent practical characteristics.

[Brief explanation of the drawing]

FIG. 1 is a model diagram showing an example of an apparatus used in the present invention, and FIG. 2 is a partially cutaway perspective view showing an example of a crucible used in the present invention. DESCRIPTION OF SYMBOLS 1... Crucible, 2... Filament for thermionic emission, 3... Electrode for electron acceleration, 4... Long film-shaped base material, 5... Supply roll, 6, 7... Guide roll, 8... Winding roll, 9... Electrode for accelerating ionized vapor particles in an electric field, L... Slit length, W... Slit width, D... Slit depth.

Claims (1)

[Claims] 1. Under high vacuum, a closed crucible with a long slit is heated, and the ferromagnetic metal supplied into the crucible is vaporized and ejected from the slit of the crucible to form a band-shaped crucible. A vapor flow is generated, and the band-shaped vapor flow is irradiated with accelerated electrons to ionize the vapor particles in the vapor flow, and the ionized vapor particles are accelerated by an electric field to form a surface of a long film-like base material. 1. A method for manufacturing a magnetic recording medium, comprising forming a thin film layer of ferromagnetic metal on the surface of the base material by making it incident over the entire width direction. 2. A slit for steam ejection that is longer than the width of the long film-like base material on which a thin film layer of ferromagnetic metal is to be formed, in a vacuum chamber that can be evacuated to a high vacuum of 8 × ¹⁰ -4 Torr or less. an accelerated electron irradiation device comprising a closed crucible in which the depth of the slit is larger than the gap between the slits, a heating means for the crucible, a filament for emitting thermionic electrons, and a plate-shaped electrode for accelerating electrons; A base material transfer device for moving a long film-shaped base material and an electrode for accelerating ionized vapor particles in which ferromagnetic metal vapor particles are ionized by the accelerated electron irradiation by the accelerated electron irradiation device with an electric field are provided. 1. An apparatus for manufacturing a magnetic recording medium, characterized in that: