JPS6262430A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good magnetic characteristics and excellent electromagnetic conversion characteristic with high output and low noise by forming a vapor-deposited non-magnetic film consisting of tin and/or tin oxide as underlying film by a diagonal incident vapor deposition method at >=40 deg. incident angle. CONSTITUTION:This magnetic recording medium is constituted by providing the underlying vapor-deposited non-magnetic film 12 on a suitable non-magnetic substrate 11 and further providing a thin vapor-deposited magnetic film 13 thereon. The diagonal incident vapor deposition is executed by depositing by evaporation a vapor deposition material 27 from a crucible 26 at the incident angle controlled by a mask 25 to deposit the vapor thereof on a substrate 23 while running the substrate along a cylindrical can 24. The min. value of the incident angle theta min. is preferably maintained at >=40 deg., more particularly preferably >=55 deg. and the max. value theta max. is maintained at 70-90 deg. in the stage of depositing the tin and/or tin oxide by evaporation as the underlying film. The vapor-deposited non-magnetic film consisting of the tin or/and tin oxide and the vapor-deposited magnetic film are preferably formed by the diagonal incident vapor deposition from the same direction with regard to the normal of the surface of the non-magnetic substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to magnetic recording media. More specifically, the present invention relates to a non-ζ-inder type magnetic recording medium used as a video tape, computer memory, digital audio tape, etc.

(Prior Art) Conventionally, coating-type recording media have been used as magnetic recording media, in which magnetic powder such as γ-F6203 is dispersed in an organic binder, and this is coated on a non-magnetic substrate and dried. There is. However, in recent years, the demand for high-density recording has increased, and magnetic iron oxide coating type recording media can no longer meet the above demand.

In magnetic recording media, the guidelines for responding to high-density recording are making the magnetic layer thinner, achieving high residual magnetic flux density, and high coercive force. The type magnetic recording medium can be said to be an ideal medium.

Among these non-binder type magnetic recording media, a medium in which a cobalt-based material is deposited using an oblique incidence deposition method has been developed as a medium for use in so-called RR mm video.
For example, it achieves a high S/N compared to metal powder-coated tape, and is expected to be the ultimate longitudinal recording type magnetic recording medium. However, simply providing a vapor-deposited magnetic film on a non-magnetic substrate poses some problems in terms of practical characteristics or production, so it is common to provide a pack layer, underlayer, intermediate layer, overcoat layer, etc. Various proposals have been made to provide an organic layer or an inorganic layer as the underlayer.
-1j No. 703: Improvement of film adhesion by silicon oxide film, JP-A-4-74! Ta, Cr, Mo
, Improvement of coercive force by oxide and nitride films such as Mn and Si, JP-A-Sho! Noise reduction by Bi2O3 film on co/j3≠or issue, JP-A-Sho! No. 3-23601: Improvement of coercive force by a composite underlayer film with controlled crystallinity, JP-A No. 3-23601.
1 France No. 772 has T 1% Ags CuXCrXA1, etc., which has a large ionization tendency, and the corrosion resistance is improved by a base film. Improvement of coercive force by geomembrane, JP-A-Sho Jr-4
2r21 improves coercive force with a base film formed by forming an island-like Bi film on a silicon or silicon oxide film, improves magnetic properties with a Bi film in JP-A Shoj Tartiz, JP-A Shoj Tar//24cλ7 The issue discloses improvement in still durability using a Bi film on a TiXCr film. Furthermore, in JP-A No. 2, Sho≠r-311107 describes the improvement of adhesion of a magnetic thin film by providing a ferrite magnetic film on a tin oxide film.
- Preventing cracks in magnetic thin films using a low-boiling metal base film such as Sn in the iozror issue, JP-A-Sho! J-A/J10
The No. 1 discloses a method for manufacturing a magnetic recording medium with relatively good coercive force by providing a vapor-deposited magnetic film not by oblique-incidence vapor deposition on an oblique-incidence vapor-deposited base film of Sn or the like with an incident angle of 30' or more. ing.

However, these methods lack magnetic properties suitable for systems with narrow tracks and short recording wavelengths such as r mm video.
Furthermore, electromagnetic conversion characteristics could not be obtained, and improvements were strongly desired.

(Objective of the Invention) An object of the present invention is to provide a magnetic recording medium having good magnetic characteristics and excellent electromagnetic conversion characteristics with high output and low noise.

(Structure of the Invention) The present invention provides a method for manufacturing a magnetic recording medium by providing a non-destructive vapor deposited film as an underlayer on a non-magnetic support and then forming a magnetic thin film by oblique incidence deposition. The present invention relates to a method of manufacturing a magnetic recording medium, characterized in that a nonmagnetic vapor deposited film made of tin and/or tin oxide is formed by an oblique incidence vapor deposition method with an incident angle of 306 or more. Here, it is preferable that the nonmagnetic deposited film and the magnetic deposited film are formed by an oblique incidence deposition method from the same direction with respect to the normal to the surface of the nonmagnetic support.

As a result of extensive research into a vapor-deposited metal thin film type magnetic recording medium provided with an underlying vapor-deposited film, the present invention has revealed that a magnetic thin film is formed by oblique-incidence vapor deposition on an underlying film made of tin and/or tin oxide by oblique-incidence vapor deposition. It has been discovered that the magnetic recording medium obtained by this method has excellent magnetic properties and electromagnetic conversion properties.

FIG. 7 shows the structure of a mountain recording medium manufactured according to the present invention. The magnetic recording medium obtained according to the present invention comprises a non-magnetic base deposited film /3 provided on a suitable non-magnetic support 11, and a deposited magnetic thin film /3 provided thereon.

The base film /2 provided on the non-magnetic support 11 is characterized by being made of tin and/or tin oxide, and there are no particular limitations on their relative proportions. However, the effects of the present invention are more pronounced when tin oxide is included. Non-magnetic supports include plastic supports such as polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, polyethylene naphthalate, etc.
I.

A metal or alloy support such as Ti1 stainless steel is used. The thickness of the base film /2 is preferably 2j to 2j O-OA. The effects of the present invention are more pronounced when the base film 4- is formed by oblique evaporation with an incident angle of 40° or more, particularly preferably jj' or more. In the present invention, the oblique incidence evaporation method is a method in which an evaporation beam is made incident on the support surface at a certain incident angle θ with respect to the normal to the support surface. During oblique incidence vapor deposition, the incident angle θ may be constant during film formation by vapor deposition, or may be changed continuously or intermittently. FIG. 1 shows a method for carrying out oblique incidence deposition. A delivery roll 211 and a take-up roll 22 are disposed within the vacuum container, and the flexible magnetic support 3 is delivered and taken up. To perform oblique incidence vapor deposition, the vapor deposition material 27 is vapor-deposited from the crucible 2t while the support member 3 is placed along the cylindrical can 2 while controlling the incident angle using the mask 2j.

The vapor deposition material 27 is heated by an electronic beam column. In FIG. 2, the incident angle continuously changes from the maximum value θmax to the minimum value θmin. In the present invention, when tin and/or tin oxide is vapor-deposited as a base film, it is preferable that θmint'' is 00 or more, particularly preferably !!0 or more, and θmax is 70'' to 20°.

The ferromagnetic thin film in the present invention is particularly characterized in that it is an alloy thin film containing cobalt as a main component or an alloy thin film containing iron as a main component. Co/9 alloys include pure cobalt, cobalt-nickel alloys, cobalt-chromium alloys, etc. Various elements may optionally be added as necessary, for example, for the purpose of improving corrosion resistance. The iron alloy may be pure iron, an iron/carbon alloy, an iron/nickel alloy, an iron/chromium alloy, or an iron nitride thin film with excellent corrosion resistance. The thickness of this magnetic film is desirably between 0.8 µm and 2 µm in order to obtain high output and high S/N. Further, this ferromagnetic thin film is preferably provided by an oblique incidence deposition method with a minimum incidence angle of 200 or more. This is desirable in order to impart coercive force suitable for high-density recording to the magnetic recording medium of the present invention.

Furthermore, it is also possible to form this ferromagnetic thin film while introducing oxygen gas, nitrogen gas, or various rare gases, for example.

According to the present invention, when forming a magnetic thin film by oblique incidence evaporation on tin or/and tin oxide formed by oblique incidence evaporation, the film made of tin or/and tin oxide is It is preferable that the magnetic vapor deposited film and the magnetic vapor deposited film are deposited with oblique incidence from the same direction.

Furthermore, it is also possible to apply a known lubricant, rust preventive, etc. on this ferromagnetic thin film, or provide a known protective layer.

A magnetic film may be provided on both sides of the non-magnetic support, or a so-called check layer may be provided on the opposite side of the non-magnetic support.

(Examples) Next, the present invention will be specifically explained using Examples, but the present invention is not limited thereto.

(Example L) A magnetic tape was prepared using the apparatus shown in FIG. 3, and after slitting it into a width of if m/m, its magnetic properties and electromagnetic conversion properties were measured.

FIG. 3 shows an example of an apparatus for carrying out the present invention,
Right chamber 3 for forming a non-magnetic deposited film inside the vacuum container 30
1 and three left ventricles for forming a magnetic thin film. The flexible non-magnetic support 33 is formed from a delivery roll 3μ to a cylindrical can 3! After passing through, it enters the left ventricle 32 from the guide roller 36.

Next, after passing through a guide roller 37 and a cylindrical can 3t, it is wound onto a winding roll 3. The material for forming the non-magnetic deposited film is evaporated from the evaporation source Hiroshi O, and the mask 4! The film is deposited by oblique incidence onto the nonmagnetic support 33 moving along the cylindrical can 3j through the cylindrical can 3j. The magnetic thin film is formed by evaporating a magnetic material from an evaporation source μλ and obliquely depositing it through a mask 43 onto a non-magnetic support 33 moving along a cylindrical can 3r. Mask≠1
．． 173 is provided with a gas inlet for introducing a desired gas such as oxygen during vapor deposition.

A polyethylene terephthalate film having a thickness of /2.1 μm was used as a support and was fed out from the feed roll shown in FIG. 3 to prepare a medium as described below. Degree of vacuum in the right ventricle
X/0-5 TOrr, the minimum incident angle was 7j, and the evaporation source was charged with Japanese knotweed and r*sn, and the evaporation was performed using a Pierce 2 E/B gun. The deposition rate and deposition thickness were monitored using a crystal oscillator monitor. After a base film was provided in the right ventricle, a ferromagnetic base film was provided in the left ventricle. Vacuum degree/ , Ox/ 0-
'TOrr incident angle 2!0, 1C of knotweed as evaporation material
A ferromagnetic film was created using an oBONi2o alloy by adjusting the power of the E/B so that the film thickness was 1000 mm.

The produced magnetic tape was slit into a width of lf m/m, and then its magnetic properties and electromagnetic conversion properties were measured. A vibrating sample magnetometer (VSM) was used to measure the magnetic properties. Further, the electromagnetic conversion characteristics were determined by incorporating an f m / m tape into a cassette, recording and reproducing with a 1 m / m video camera recorder FUJI-1, and measuring the S/N with an S / N meter.

For comparison, we used the apparatus shown in Figure 3 to create a magnetic film on a tape with no base film and while oxygen gas was introduced from the gas inlet at 1/000 CC/M during CoaoNizo deposition in the left ventricle. Prepared.

Table 1 shows the measurement results. Sample No. 1 has no base film and only a ferromagnetic film. φ, ≠ 3 is the same magnetic film as +/ provided on top of tin + tin oxide underlayer. In addition, φ≠ indicates that no base film was provided and oxygen gas was introduced at a rate of /000”/y1 during the production of the magnetic film.In samples ÷2 and ÷3, the coercive force Hc increased to the same level as φ≠, and the noise was further increased. It can be seen that the medium has an extremely good S/N ratio.

Table 1 (Example-2) Using the same equipment as in Example 1, the base film thickness was 1000^
The influence of the minimum incident angle during base film deposition was investigated (Table 2). When the angle of incidence is small, the effect of the present invention is small;
Especially when the angle of incidence is 40° or more! It can be seen that 30 or more is preferable.

Table 2 (Example-3) Using the same apparatus as in Example 1, an iron film was provided as a ferromagnetic film. The conditions for forming the base film were the same as in Example-1. In the left ventricle, polygonum and touch iron were used as evaporation materials, and the incident angle was set to t0. Also, during magnetic film deposition, the left ventricular pressure was
, 2 x 70-4 Torr. Table 3 shows the measurement results. By installing a base film, high coercive force can be obtained even with iron-based films.

Table 3 As described above, when an obliquely evaporated magnetic film is provided on an obliquely evaporated base film of tin and/or tin oxide, the magnetic properties and electromagnetic conversion characteristics are improved.

The above effect could not be obtained with a base film such as Al1% Cr % Z n % P b.

(Effects of the Invention) As described above, the magnetic recording medium produced by the method of the present invention has excellent magnetic properties, a high S/N%, and an excellent noise reduction effect.

[Brief explanation of drawings]

FIG. 1 shows the structure of a magnetic recording medium manufactured according to the present invention. FIG. 2 shows one method of carrying out oblique incidence deposition, and FIG. 3 shows an example of an apparatus for carrying out the invention. ll: support, 12: base film, 13: magnetic film, 2/, 3
4t: Delivery roll 22.3 Take-up roll 23.33: Non-magnetic support 2≠, 3s, 3t: Cylindrical can 2, Hiro/, ≠3: Maskco 6, ≠O, lI-coni evaporation Source 31. 37: Guide roller Hiro≠,≠yo: Gas inlet Patent applicant Fuji Photo Film Co., Ltd. Figure 1 Figure 2

Claims (2)

[Claims] (1) In a method of manufacturing a magnetic recording medium by providing a non-magnetic evaporated film as a base film on a non-magnetic support and then forming a magnetic thin film by oblique incidence deposition, the base film may contain tin and/or oxide. A vapor-deposited film made of tin is deposited at an incident angle of 40
A method for manufacturing a magnetic recording medium, characterized in that the magnetic recording medium is formed by an oblique incidence evaporation method with an angle of at least 100°C. (2) The non-magnetic deposited film and the magnetic deposited film are formed by an oblique incidence deposition method from the same direction with respect to the normal to the surface of the non-magnetic support. A method for manufacturing a magnetic recording medium.