JPS63308721A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a titled recording medium having excellent electromagnetic conversion characteristics and durability by consisting a protective film of an aggregate of columnar particles which consist of Ni or alloy essentially consisting of Ni and in which part thereof forms an oxide and forming these particles so as to continue to the columnar particles of a magnetic recording layer. CONSTITUTION:A polyimide film is used as a nonmagnetic substrate 4 and metal or alloy such as Co or Co-Ni or the oxide thereof is formed by a continuous diagonal vapor deposition method as the magnetic recording layer 11 which is a ferromagnetic metallic layer. The protective film 12 to be provided thereon is formed by continuous diagonal vapor deposition and is formed of the aggregate of the columnar particles which consist of Ni or the alloy essentially consisting of Ni and in which part thereof forms the oxide. The protective film 12 formed on the magnetic recording layer 11 consisting of the aggregate of the inclined columnar particles is also formed of the aggregate of the columnar particles and both these aggregates 11, 12 are made into the continuous structure. The incident angle of the particles at the time of the diagonal vapor deposition of the protective film 12 is preferably set slightly smaller than the incident angle at the time of the diagonal vapor deposition of the magnetic recording layer 11 for the above-mentioned purpose.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium in which a ferromagnetic metal layer and a protective film are sequentially formed on a nonmagnetic substrate.

(Prior art) Magnetic recording media in which a ferromagnetic metal layer such as cobalt or cobalt alloy is formed on a nonmagnetic substrate such as a plastic film have excellent high-density recording characteristics, but on the other hand, the metal is exposed on the surface. Because of this, it is corroded by moisture present in the atmosphere and corrosive gases such as SO, SO, NOT, etc., resulting in a decrease in the amount of saturation magnetization, and furthermore, corrosion products cause poor running of the magnetic recording medium.

Conventionally, in order to eliminate these drawbacks, (1) a protective film made of cobalt or nickel oxide was provided on the ferromagnetic metal layer (Japanese Unexamined Patent Publication No. 193536/1982);
, (forming a corrosion-resistant protective film of 21Ni or Ni alloy (JP-A-53-7205), (3) providing an oblique evaporation layer of nickel on the ferromagnetic metal layer at an incident angle of 60° or more ( Japanese Unexamined Patent Publication No. 54-21305) and the like have been proposed.

[The point that the invention attempts to solve]

However, since the magnetic recording medium (No. 11) has a non-magnetic protective film, there is a large spacing loss, and the formation of the protective fill reduces the reproduction output. If the thickness is too thin, the protective film cannot function for a long time.

Further, although the magnetic recording medium (2) prevents spacing loss due to the thickness of the protective film, it causes deterioration of the S/N ratio as an electromagnetic conversion characteristic, and furthermore, there is a problem of lack of durability. Furthermore, the magnetic recording medium (3) has a drawback of poor wear resistance.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a magnetic recording medium that has excellent corrosion resistance, wear resistance, and electromagnetic conversion characteristics.

[Means for solving problems]

The present inventors have improved corrosion resistance, especially resistance to corrosive gases such as sulfur dioxide gas, by using Ni or an alloy containing Ni as a main component for the protective film, and made part of this protective film an oxide. , and columnar particles that are continuous with the magnetic recording layer, improve the adhesion between the magnetic recording layer and the protective film, increase the rigidity of the protective film itself, eliminate strength distortion caused by the overall structure of the film, and improve durability. and corrosion resistance. Furthermore, by imparting magnetism to the protective film and forming it from columnar grains that are continuous with the magnetic recording layer, distortion of the magnetization distribution when recording signals is reduced, and the spacing is reduced without deteriorating the S/N ratio. We have found that losses can be minimized. The present invention was completed based on the above findings, and in order to achieve the above object, the present invention forms a magnetic recording layer consisting of an aggregate of inclined columnar particles on a non-magnetic substrate, In the case where a protective film is formed on the magnetic recording layer, the protective film is made of Ni.
or an aggregate of columnar particles made of an alloy containing Ni as a main component and at least a portion of which forms an oxide, and characterized in that the columnar particles are continuous with the columnar particles of the magnetic recording layer. It is something.

Furthermore, in order to achieve the above-mentioned object, the present invention is characterized in that a lubricating layer is provided on the above-mentioned protective film.

〔Example〕

In the present invention, examples of the nonmagnetic substrate include polyethylene terephthalate film, polyimide film,
In addition to commonly used plastic films such as polyester film, composite substrates mixed with or coated with inorganic substances such as carbon fiber, copper, and silicon, nonmagnetic metals such as aluminum, and glass may also be used.

Examples of materials for forming the ferromagnetic metal layer include C01C.
o-Ni, Co-Ti, Co-Fs.

Metals or alloys such as Co-Cr, Co-p, Co-Ni-Cr, or oxides thereof are used. As a means for forming this ferromagnetic metal layer, continuous diagonal seven-layer deposition is applied.

Further, as a means for forming the protective film, there is continuous oblique vapor deposition.

In the present invention, the magnetic recording layer consists of an aggregate of inclined columnar particles, and the protective film also consists of an aggregate of columnar particles, but these aggregates need to have a continuous structure. When the above-mentioned particle aggregates do not have a continuous structure, the electromagnetic conversion characteristics indicated by the S/N ratio deteriorate. In this case, the magnetic recording layer is formed by an oblique vapor deposition method and forms an aggregate of inclined particles. Therefore, in order to make the aggregate of particles constituting the retention fill continuous with respect to the magnetic recording layer, it is necessary to It is desirable to adopt a means for making the incident angle of particles on the protective film slightly smaller than the angle of incidence of particles on the recording layer during oblique vapor deposition.

In the present invention, the protection 1! It is even more effective if a lubricating layer is formed on the film. As the lubricant, for example, an aliphatic lubricant, a fluorine-based lubricant, a silicone-based lubricant, or a hydrocarbon-based lubricant is suitably used.

As the aliphatic lubricant, fatty acids, metal salts of fatty acids, fatty acid esters, fatty acid amides, aliphatic alcohols, etc. are used. Examples of the fatty acids used include uralic acid, myristic acid, palmitic acid, oleic acid, stearic acid, and behenic acid. Examples of these metal salts include magnesium salts, aluminum salts,
Lithium salts, sodium salts, calcium salts, iron salts, cobalt salts, zinc salts, barium salts and lead salts are used.

As the fatty acid ester, for example, butyl stearate, octyl myristate, stearic acid monoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride, etc. are used.

Examples of the fatty acid amide include caproic acid amide,
Capric acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, methylene bisstearic acid amide, etc. are used.

Examples of the aliphatic alcohol used include stearyl alcohol and myristyl alcohol.

In addition, chlorides such as trimethylstearylammonium chloride and stearoyl chloride, and amines such as stearylamine, stearylamine acetate, and stearylamine hydrochloride can also be used.

As the fluorine-based lubricant, for example, trichlorofluoroethylene, perfluoropolyether, perfluoroalkyl polyether, perfluoroalkyl carboxylic acid, etc. are used. Specific examples of these commercially available products include Guyfron 201 manufactured by Daikin Industries, Krytx M, Talytx H5 Vydax A and R manufactured by Duyupoff, and Fonprin Z manufactured by Montageson.

As the silicone lubricant, for example, silicone oil, modified silicone oil, etc. are used.

As the hydrocarbon lubricant, paraffin, squalane, wax, etc. are used, for example.

The lubricant layer may be composed of only a lubricant, or may contain an appropriate amount of an antidepressant.

Examples of the rust preventive include butylhydroxyanisole, dibutylhydroxytoluene, benzotriazole, benzotriazole laurylamine, hydroquinone, dimethylaminoethylene methacrylate, triphenylphosphite, tridecylphosphite, trilauryltrithiophosphite, trilauryltrithi Phenol type, amine type, phosphorus type, ionic type, organic acid type, quinone type, etc. are used, such as ofophosphite, butyl phosphate, dilauryl thiodipropionate, sorbitol, propylene glycol, and hydroquinone.

FIG. 1 is a schematic diagram of a vacuum evaporation apparatus for manufacturing a magnetic recording medium according to an embodiment of the present invention.

In the vacuum chamber 2 evacuated by the exhaust system 1, the substrate 4 made of a non-magnetic material is sent out from the delivery roll 3.
While moving along the cylindrical can 5, the incident angle of the vapor flow 7 of the evaporator B6 disposed at the bottom is determined by the deposition prevention plate 8, and the vapor is continuously and obliquely deposited on the substrate 4, and then rolled onto the take-up roll 9. be wound up.

Further, when Ni or Ni alloy is partially oxidized during the vapor deposition operation when forming the protective film, oxygen gas is introduced from the gas inlet 10. The gas introduced through the gas inlet 10 is preferably a gas obtained by mixing oxygen gas with an inert gas such as nitrogen gas, argon gas, or helium gas, in addition to oxygen gas.

When manufacturing the magnetic recording medium of the present invention, two vacuum evaporation apparatuses shown in FIG. 1 are installed, and one apparatus forms a magnetic recording layer on the substrate 4, and then the second apparatus It is also possible to apply binary vapor deposition or multistage vapor deposition to form a protective film on the magnetic recording layer 13.

Example 1 A commercially available polyethylene terephthalate film with a thickness of 9 μm was used as the substrate 4, and a commercially available polyethylene terephthalate film with a thickness of 9 μm was used as the magnetic recording layer.
Using a Co8O-Ni20 alloy as the evaporation source 6 and adjusting the deposition prevention plate 8 so that the incident angle is in the range of 55° to 90'', continuous oblique evaporation is performed while introducing oxygen gas from the gas inlet 10. , Co-N with a film thickness of 15 (11) people
A magnetic recording layer consisting of i-0 was formed.

Next, Ni was continuously deposited obliquely onto the magnetic recording layer using an evaporation source 6 while introducing oxygen gas at an incident angle of 55° to 40°, and Co-Ni was deposited on the substrate 4 as shown in FIG.
A magnetic recording medium was formed by forming a magnetic recording layer 11 of -0 with a thickness of 15 (11) thick, and further forming a protective film 12 of Ni-0 with a thickness of 2 (11) thick.

Example 2 Protect! In addition to using N1-20Fe as the evaporation source for the i-film,
In the same manner as in Example 1, a thickness of 2 (2) made of Ni-Fe-0 was
11) A protective film was formed to obtain a magnetic recording medium.

Comparative Example 1 In Example 1, the incident angle at the time of forming the protective film was set to 55°~
A magnetic recording medium as shown in FIG. 3 was formed in the same manner as in Example 1 except that the angle was 90°.

Comparative Example 2 A magnetic recording medium was formed in the same manner as in Example 1 except that the introduction of oxygen gas during the formation of the protective film was omitted.

The magnetic recording media obtained in Example 1.2 and Comparative Example 1.2 were evaluated for magnetic properties using SSM, and were tested using a recording and reproducing device prototyped using a commercially available VTR.
The electromagnetic conversion characteristics show the playback output when a 5MH2 signal is recorded and played back and the playback output of a comparative magnetic tape without a protective film is set to OdB, and the still time of the magnetic tape was measured using a VH3 VTR. The durability was evaluated by Corrosion resistance is 60℃, 90%RH high temperature and humid atmosphere and II)I)m 30w gas (35℃, 75%RH)
In the atmosphere, each was left undisturbed for 24 hours for 7 days,
It was expressed as the amount of decrease in saturation magnetization before and after standing still, and was also observed with the naked eye.

As is clear from Table 1, in the examples in which the protective film on the magnetic recording layer is made of aggregates of inclined columnar particles, these aggregates are made continuous, and Ni is the main component of 81M, both electromagnetic This shows that it has excellent effects in all aspects of conversion characteristics, durability, and corrosion resistance.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a magnetic recording medium that has excellent corrosion resistance, electromagnetic conversion characteristics, and durability.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of a vacuum evaporation apparatus for manufacturing a magnetic recording medium according to an embodiment of the present invention, Fig. 2 is a sectional view showing an embodiment of the present invention, and Fig. 3 is a comparative example. 1 is a cross-sectional view showing a magnetic recording medium of FIG. 2... Vacuum chamber, 4... Substrate, 6...
... Evaporation source, 7... Vapor flow, 8...
Anti-adhesion plate, 10...Gas inlet, 11...
-Magnetic recording layer, 12...protective film. Figure 1 Figure 2 Figure 3

Claims (12)

[Claims] (1) A magnetic recording layer consisting of an aggregate of tilted columnar grains is formed on a nonmagnetic substrate, and a protective film is formed on this magnetic recording layer, where the protective film contains Ni or Ni as a main component. What is claimed is: 1. A magnetic recording medium comprising an aggregate of columnar grains, at least a part of which forms an oxide, and the columnar grains are continuous with the columnar grains of the magnetic recording layer. (2) A magnetic recording medium according to claim (1), wherein the magnetic recording layer is made of cobalt alone or an alloy containing cobalt as a main component. (3) In claim (2), the alloy containing cobalt as a main component is Co-Ni, Co-Cr, Co-Ni, Co-Cr,
Co-Ni-Cr, Co-P, Co-Ti and Co-
A magnetic recording medium characterized in that it is an alloy selected from the group of Mn and Co-Fe. (4) In claim (1), the alloy containing Ni as a main component is Ni-Fe, Ni-Cr, Ni-A
1. A magnetic recording medium comprising one type of alloy selected from the group consisting of 1, Ni-Co, and Ni-Mn. (5) A magnetic recording layer made of an aggregate of tilted columnar grains is formed on a nonmagnetic substrate, and a protective film is formed on this magnetic recording layer, where the protective film contains Ni or Ni as a main component. The magnetic recording layer is composed of an aggregate of columnar particles, at least a part of which forms an oxide, and the columnar particles are continuous with the columnar particles of the magnetic recording layer, and a lubricant layer is provided on the protective film. A magnetic recording medium characterized by: (6) A magnetic recording medium according to claim (5), wherein the magnetic recording layer is made of cobalt alone or an alloy containing cobalt as a main component. (7) In claim (5), the alloy containing cobalt as a main component is Co-Ni, Co-Cr, Co-Ni, Co-Cr,
Co-Ni-Cr, Co-P, Co-Ti and Co-
A magnetic recording medium characterized in that it is an alloy selected from the group of Mn and Co-Fe. (8) In claim (5), the alloy containing Ni as a main component is Ni-Fe, Ni-Cr, Ni-A
1. A magnetic recording medium comprising one type of alloy selected from the group consisting of 1, Ni-Co, and Ni-Mn. (9) A magnetic recording medium according to claim (5), wherein the lubricant layer is made of an aliphatic lubricant. (10) A magnetic recording medium according to claim (5), wherein the lubricant layer is made of a fluorine-based lubricant. (11) A magnetic recording medium according to claim (5), wherein the lubricant layer is made of a silicone lubricant. (12) A magnetic recording medium according to claim (5), wherein the lubricant layer is made of a hydrocarbon lubricant.