JPS6194239A - Preparation of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a magnetic characteristic by using at least two electron beams to scan an electron beam scan area on an evaporation source for magnetic material set in parallel to the width direction of a nonmagnetic substrate, and making the scan frequencies of both electron beams different in phase. CONSTITUTION:A scan area 19 is formed approximately in parallel to the width direction of a tape type nonmagnetic substrate 12 which moves along the surface of a cooling can 11. The electron beams 17 and 18 delivered from electronic guns 15 and 16 have scan frequencies set at different phases. These beams are controlled so as not to irradiate the same part of the area 19 at a time. The phase of the electron beam is shifted by 360 deg./n when the number of beams irradiating the area 19 is set at (n). Then the moving speed of the substrate 12 is set at upsilon(m/min) together with the scan width of the area 19 set at omega(m) respectively. Under such conditions, the scan frequency of the electron beam is set at 2omegaupsilon/n(Hz) or more. A magnetic recording medium thus produced excels in magnetic characteristic and also can be used as an excellent magnetic record ing medium of a vapor-deposited thin film type.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a magnetic recording medium by forming a magnetic thin film on a tape-shaped nonmagnetic substrate such as a moving polymer molded article by vacuum deposition.

Furthermore, the present invention relates to a method of manufacturing a magnetic recording medium with improved magnetic properties and electromagnetic conversion properties.

[Prior art]

Conventionally, as a magnetic recording medium, r-F
e203s Co-doped r-Fe203, Fe
Fl doped with 5Oa, Co! 304% r-Fe2
Powder magnetic materials such as bertolide compounds of 0s and Fe3O4, co-doped belt 2ide compounds, oxide magnetic powders such as CrO2, or alloy magnetic powders whose main components are l'e, Co, Ni, etc., are made of vinyl chloride. Coating-type materials have been widely used, in which they are dispersed in an organic binder such as vinyl acetate copolymer, styrene-butadiene copolymer, epoxy resin, or polyurethane resin, coated, and dried.

In recent years, with the demand for high tb for high-density magnetic recording, ferromagnetic metal thin films formed by methods such as vacuum evaporation, sputtering, and ion plating have become so-called metal thin-film type magnetic recording that does not use a binder. It has attracted attention as a medium and has been put into practical use. Conventional coating-type magnetic recording media mainly use metal oxides with low saturation magnetization as magnetic materials.
'Since the volume content of the magnetic material in the magnetic layer is only 30 to ZOS, it has reached its limit as a high-output, high-density recording medium. Furthermore, the manufacturing process is complicated and requires large incidental equipment for solvent recovery and pollution prevention.Metal thin film magnetic recording media have a larger saturation magnetization than oxide magnetic materials. It has the advantage of being able to form extremely thin films of ferromagnetic metals without intervening non-magnetic substances such as organic binders.With the trend toward higher density magnetic recording, the gap length of recording/reproducing magnetic heads is now less than 7.0 μm. However, the recording depth in the magnetic recording layer also tends to become shallower, and metal thin film magnetic recording media, in which the entire thickness of the magnetic film can be used to record magnetic signals, are extremely difficult to use as high-power, high-density recording media. Among metal thin film magnetic recording media, the method of forming a film by vacuum evaporation has the advantages of a fast film formation speed, a simple manufacturing process, and a dry process that does not require drainage treatment. Among these, the oblique incidence vacuum evaporation method, in which the evaporation beam of a magnetic metal is incident obliquely on the surface of a non-magnetic substrate, is relatively simple in terms of process and equipment structure. This method is excellent in practical use because a film with good magnetic properties can be obtained.

When manufacturing a magnetic tape by forming a magnetic thin film on a tape-shaped non-magnetic substrate by vapor deposition, the method disclosed in Japanese Patent Application Laid-Open No.
No. 0, JP-A-3-17706, a method is used in which a vapor flow of a magnetic material evaporated by irradiation and heating with an electron beam is directly deposited on a moving tape-shaped nonmagnetic substrate. It will be done. The vapor-deposited magnetic recording medium produced in this manner has a higher output than conventional coating-type magnetic recording media, and is therefore extremely promising as a magnetic tape for J'mm VTRs or a magnetic tape for digital audio. In vapor deposition type magnetic recording media, a method is used in which oxidizing gas such as oxygen is introduced during vapor deposition of magnetic material in order to reduce noise and further improve S/N. Since the characteristics, especially K(dH)max, have deteriorated, improvements have been desired. Further, in the conventional evaporation type magnetic recording medium using the electron beam heating method, the envelope of the recording/reproducing wave especially for high frequency signals such as video signals is insufficient, and improvements in this regard have been desired.

[Purpose of the invention]

The object of the present invention is to provide a magnetic thin film type magnetic recording medium using a vapor deposition method that improves the above-mentioned drawbacks.
An object of the present invention is to provide a method for manufacturing an improved magnetic thin film type magnetic ax recording medium. A further object of the present invention is to provide a method for manufacturing a magnetic thin film type magnetic recording medium using a vapor deposition method that has excellent electromagnetic conversion characteristics, particularly the envelope of a reproduced signal.

[Structure of the invention]

In the present invention, a magnetic thin film is deposited on a tape-shaped non-magnetic substrate that moves continuously in a vacuum atmosphere, and the vapor of a magnetic material evaporated by scanning heating with an electron beam is directed onto the non-magnetic substrate to form a magnetic thin film. In a method for manufacturing a medium, an electron beam scanning area on a magnetic material evaporation source that is substantially parallel to the width direction of the non-magnetic substrate is scanned with at least one electron beam, and the phase of the scanning frequency of each electron beam is set to be different from K. The present invention relates to a method of manufacturing a magnetic recording medium, characterized in that:

FIG. 1 shows an example of an apparatus for carrying out the method of manufacturing a magnetic recording medium according to the present invention. A tape-shaped nonmagnetic substrate is conveyed along a cylindrical cooling can disposed in a vacuum chamber (not shown) equipped with a suitable evacuation system. A crucible /4t for heating and vaporizing the magnetic material /3 is placed below the cooling can //, and the magnetic material /3 is equipped with two electron guns /! , /1 are heated by irradiation with electron beams /7, /♂. The vapor flow of the heated and evaporated magnetic material reaches the surface of the tape-shaped differential member moving along the surface of the cooling can, forming a deposited magnetic thin film. 2 electron guns/! , /electron beam from /7,
/I is designed to scan and irradiate the scanning area /3 of the magnetic material /3 inside the crucible /4. 7. The scanning area is a tape-shaped non-magnetic material that moves along the surface of the cooling can.
It is approximately parallel to the width direction of 2. 2 electron guns/j1
The electron beams /7, // from /6 are set so that the phases of their scanning frequencies are different, and the - electron beams /2, /r do not simultaneously irradiate the same part of the scanning area /2. It looks like this. It is particularly preferred that the phases of the electron beams are shifted by 360', where n is the number of electron beams irradiating the scanning area. Furthermore, when the moving speed of the tape-shaped non-magnetic substrate is υ (m/min) and the scanning width of the scanning area is ω (m), the scanning frequency of the electron beam is ωυ n (Hz) or more, Particularly preferably, it is -V (Hz) or higher. As a result of various studies on vapor deposition by electron beam scanning, the present inventors found that a magnetic recording medium manufactured by scanning at least one electron beam with a shifted phase has excellent magnetic properties and has excellent electromagnetic conversion properties. Discovered that it was a thin film magnetic recording medium,
This led to the present invention.

When manufacturing a magnetic recording medium by the method of the present invention, the ferromagnetic metal used to form the magnetic thin film is Fe5C.
o, metals such as Ni or Fe-C to Fe-Ni, Co
-Ni, Fe-Co-Ni, Fe-Rh, Fe-Cu,
Fe-8i, Co-Cu, Co-Au, Co-Y, Co
-La, Co-Pr, Co-Gd.

Co-8m, Co-PL, Co-8i, Co-Mn.

Co-PXNi-CuSMn-Bi, Mn-5b.

Mn-A, CFe-Cr5Co-Cr, Ni-Cr.

Fe-P, N1-PXCo-Ni-P, Co-N1-B
, Co-Ni-Ag, Co-Ni-Cr, Fe-Co-
Cr, Fe-Co-Ni-Cr, Co-Ni
Ferromagnetic alloys such as -Zn, Co-N1-W, Fe-Co-N1-P, etc. are used. The thickness of the magnetic film is generally from 0.02 μm because it needs to be thick enough to provide sufficient output as a magnetic recording medium and thin enough to provide sufficient space for high-density recording! , θμm1 preferably θ, Ojpm
2.0 μm.

Note that a gas such as 02% CO2, N2, NHs, or styrene may be introduced during vapor deposition to cause elements such as O, N, and C to be contained in the magnetic thin film.

Examples of tape-shaped nonmagnetic substrates include polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate, polyethylene sulfide, and other zoystic bases, or AlXAl! Metal strips such as alloys, Ti, Ti alloys, stainless steel are used.

To replenish the evaporated magnetic material/3 from the crucible/4t, place linear, granular, band-shaped, and rod-shaped magnetic materials into the crucible/4t.
A mechanism may be provided for supplying water continuously or intermittently from above, below or from the side.

Furthermore, when using the oblique incidence vacuum evaporation method in which the vapor flow of the magnetic material is obliquely incident on the surface of the tape-shaped substrate, the incident angle is set to 30.
It is preferable to set it in the range of ° to 00.

Furthermore, in the present invention, an underlayer made of an organic or inorganic material may be provided on the tape-shaped nonmagnetic substrate. The magnetic thin films may be multilayered, or an intermediate layer made of organic or inorganic material may be provided between each magnetic film.

Further, a protective layer made of organic or inorganic material may be provided on the magnetic film.

〔Example〕

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example/A ferromagnetic thin film was formed on a 72 μm thick polyethylene terephthalate film using the apparatus shown in FIG. 7 to produce a magnetic recording medium. Co-Ni (
Ni 2i (wt%) was charged in a crucible and heated and evaporated by electron beam irradiation from one electron gun at an acceleration voltage of J j kV.

The scanning width of the electron beam is θ, jm, and the scanning frequency is 30Hz.
, the moving speed of polyethylene terephthalate film is 1
0m7 minutes. During vapor deposition, oxygen was introduced near the vapor flow, and a magnetic thin film was formed with IICL and a film thickness of 0-/Jpm so that the degree of vacuum was /,♂X70''-'Torr, and a magnetic tape was manufactured. .

Electron gun/! Sample magnetic tape obtained using chisel/
A magnetic tape obtained using only an electron gun/g was used as a sample. Furthermore, both of the two electron guns /j and /l are used, and the phase difference of the scanning frequency is set to θ°, 90°, and 90°, respectively.
/100 magnetic tapes were used as samples j, g,
I made it j.

We measured the magnetic characteristic B-H curve of the magnetic tape obtained in this way, and the envelope characteristics when a jMHz signal was recorded and played back with a VTR with a tape and head relative speed of 3.7 J-m7 seconds. It was as shown in the table below.

@(1) B-H characteristics were measured using a vibrating magnetometer by applying an external magnetic field j 000 Ce, (dH) ma
x was determined as a relative value.

(2) The envelope is next! Judgment was made on a graded basis.

◎ Very Good O Good Δ Average It was confirmed that the D value was improved and excellent envelope characteristics were exhibited.

Example λ In a device similar to Example/, three electron guns are installed. K on μm thick polyimide film
A magnetic recording medium was manufactured by forming a ferromagnetic thin film composed of CoCr (Cr: jw t To ). Vacuum degree/, jX10-8 TorrK and film thickness O, Co! A magnetic thin film was formed to have a thickness of μm. The scanning width of the electron beam is 082 m.

The scanning frequency was j)Hz, and the moving speed of the polyimide film was 10 ml/min. Sample 4 is a magnetic tape obtained using only seven electron beams, and the phase value of the scanning frequency is o O1Δ00, /20° using all three electron guns.
The magnetic tapes obtained as
It was ta. The 7max value and envelope characteristics of these samples were measured in the same manner as in Example, and the results were as shown in the table below.

It was confirmed that the vapor-deposited magnetic tape obtained by changing the phases of the scanning frequencies of the three electron beams in this way has an improved (H)max value and exhibits excellent envelope characteristics.

〔Effect of the invention〕

According to the method of manufacturing a magnetic recording medium using the vapor deposition method of the present invention, it is possible to obtain a magnetic recording medium with improved magnetic characteristics and electromagnetic conversion characteristics.

In high-density recording, as the recording wavelength becomes smaller, the self-demagnetization loss increases, so it is necessary to increase the value of Hmax. According to the method of the present invention, a magnetic recording medium suitable for this purpose can be manufactured.

In order to obtain even better VTR reproduced images, it is necessary to have an excellent envelope, and according to the present invention, it is possible to obtain a magnetic thin film type magnetic recording medium with an improved envelope.

[Brief explanation of drawings]

FIG. 7 shows an example of an apparatus for implementing the method of manufacturing a magnetic recording medium according to the present invention. l/Rainbow cylinder-shaped cooling can lλ: Tape-shaped non-magnetic substrate/3: Magnetic material/Mite M source crucible/! , lgo:electron gun/7, //:electron beam/ri:scanning area

Claims (1)

[Claims] A vapor flow of a magnetic material evaporated by scanning heating of an electron beam is directed onto a tape-shaped nonmagnetic substrate that moves continuously in a vacuum atmosphere, and a magnetic thin film is formed on the nonmagnetic substrate to form a magnetic recording medium. In the method of manufacturing the non-magnetic substrate, an electron beam scanning area on a magnetic material evaporation source substantially parallel to the width direction of the non-magnetic substrate is scanned by at least two electron beams, and the scanning frequency of each electron beam is set to have a different phase. A method of manufacturing a magnetic recording medium, characterized in that: