JPH07254125A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain high output and to improve CSS durability by laminating a film, ferromagnetic metal thin film, hard carbon film and lubricant layer on a nonmagnetic substrate. CONSTITUTION:An Al-alloy nonmagnetic substrate 5 is subjected to surface polishing but not to anodizing treatment. A polyester film 6 has a fine particle coating layer having dispersion of fine particles in a resin in 1-10mum thickness. A ferromagnetic metal thin film 7 of Co-base alloy consists of aggregation of columnar fine particles showing good magnetic separation among the columnar particles. The hard carbon film 8 has <=100Angstrom thickness and has excellent durability, and is formed by sputtering a graphite target or plasma CVD method with methane gas or the like. A lubricant layer 9 is formed by wet coating or vapor deposition. The substrate 5 and the film 6 are adhered with an adhesive 9. By this method, the polymer film 6 absorbs the stress from a head to prevent damages, so that even when the diamond-like hard carbon film 8 is made thin, durability can be maintained and high output is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a magnetic layer of a ferromagnetic metal thin film suitable for high density magnetic recording.

[0002]

2. Description of the Related Art With the progress of information society, the amount of information to be recorded is remarkably increasing, and it is required to increase the recording density of magnetic recording as much as possible. The development of magnetic recording media has continued, and the density of magnetic disks has been increased approximately 20 times in 10 years.

Particularly, in the state of the art, a magnetic recording medium has been developed in which a sputtered magnetic thin film has a large coercive force, and a hard carbon film and a lubricating layer are further arranged on the sputtered magnetic thin film. The conventional magnetic recording medium will be described below.

FIG. 3 shows an enlarged cross section of a conventional magnetic recording medium. In FIG. 3, reference numeral 1 denotes a polished Al-Mg alloy, a film of alumite, Ni-
A non-magnetic substrate provided with a P coating, 2 is Ni-Co, Co
A ferromagnetic metal thin film such as -Cr-Ta, 3 is a protective film such as a sputtered carbon film or a zirconium oxide film, and 4 is a lubricant such as perfluoropolyether.

[0005]

However, in the above-mentioned conventional structure, if the CSS characteristics in a high humidity environment are sufficient, there is a problem that the protective film becomes thick and the recording performance is impaired in the high density region. Was.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic recording medium having both durability and high output characteristics, which enables narrow track high density recording.

[0007]

In order to achieve this object, a magnetic recording medium of the present invention comprises a film on a non-magnetic substrate,
It is formed by laminating a ferromagnetic metal thin film, a hard carbon film, and a lubricant layer.

[0008]

With this structure, the stress caused by the so-called head crush, which is received from the magnetic head, is relieved by the polymer film, and the durability can be ensured even if the hard carbon film as the protective film is thinned. Thus, it is possible to realize a magnetic recording medium having a high level of balance between durability and durability.

[0009]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 5 denotes a non-magnetic substrate which is made of an aluminum alloy or the like and which requires surface polishing but does not require texture processing or the like and does not require alumite treatment. 6 is a film such as a polyester film or a polysulfone film, which may be a film having a fine particle coating layer in which ultrafine particles are dispersed and fixed with a resin, or a composite structure formed by two-layer extrusion, and the thickness is in the range of 1 to 10 μm. The surface roughness and the mechanical strength may be appropriately set to values obtained by optimization study. Reference numeral 7 denotes a ferromagnetic metal thin film made of a Co-based alloy, which is not particularly limited in the direction of the easy axis of reinforcement, the number of constituent layers, the forming method, etc., but the structure is an aggregate of columnar fine particles, and the magnetic separation between the respective columnar fine particles is performed. Is preferable. Although the manufacturing method is not limited, it is preferable to use a film wound and manufactured by electron beam evaporation.

Reference numeral 8 is a hard carbon film, and it is necessary to prepare it by a method and conditions capable of forming it with excellent durability at 100 Å or less. For forming the hard carbon film, sputtering using graphite as a target and plasma CVD using methane gas or the like are suitable. Reference numeral 9 denotes a lubricating layer, which may be natural or synthetic, and may be formed by either wet coating or vacuum deposition. 10 is an adhesive.

The effects of this embodiment will be clarified below by further comparing the specific example with the conventional example. With a thickness of 1.8 μm,
Longitudinal direction and width direction 500,560 [Kg / mm ² ]
Young's modulus of 8 to 10 [pieces / μ
² ] Use the polyethylene aphthalate film
It moves along a rotary can with a diameter of 50 cm (temperature 150 to 280 ° C), at which time the oxygen atom has a minimum incident angle (37 degrees).
While irradiating from the portion, Co is electron beam evaporated at an incident angle of 64 degrees to 37 degrees to form a perpendicularly magnetized film having a thickness of 0.2 μm, and methane gas and argon gas are used for 10 K.
2mm thick aluminum with 8nm diamond-like hard carbon film deposited by high frequency plasma CVD method of Hz, 4nm of perfluoroarachidic acid coated on it, processed into a disk of 5 inch diameter and polished with epoxy adhesive. It was bonded to an alloy substrate and finished into a magnetic disk.

In the comparative example, a surface of a polished aluminum alloy plate is anodized and textured, and then a Cr underlayer of 0.15 μm is formed by a high frequency sputtering method. Further, the same magnetic characteristic Co—O perpendicular magnetization as that of the example is formed thereon. The film is 0.22 μm by high frequency magnetron sputtering method.
Formed, targeting graphite, 25 nm
A magnetic disk was used in which (Comparative Example A) and 10 nm (Comparative Example B) hard carbon films were arranged, and 4 nm of perfluoropolyether was applied. The recording linear density is 100KFRPI, the track density is 3KTPI, and the characteristics compared with the Mn-Zn ferrite head are summarized in (Table 1).

[0014]

[Table 1]

As is clear from (Table 1), the magnetic recording medium according to the present embodiment has an excellent effect that durability and high output can be realized in high density recording in narrow track recording.

As described above, according to the present embodiment, the magnetic recording medium is constructed by laminating the film, the ferromagnetic metal thin film, the hard carbon film, and the lubricant layer on the non-magnetic substrate, so that the stress from the head is reduced. Since the polymer film absorbs less damage and the diamond-like hard carbon film becomes thinner, durability can be ensured, and high output and important CSS durability are balanced at a high level. A magnetic recording medium can be realized.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is an enlarged sectional view of a magnetic recording medium showing a second embodiment of the present invention. In FIG. 2, the same components as those in FIG. 1 are shown with the same numbers. Reference numeral 11 is a ferromagnetic metal thin film having a protrusion 12 when viewed from the magnetic head side and a minute recess 13 when viewed from the opposite side. The protrusion 12 is a ferromagnetic metal even if a hard carbon film 8 and a lubricant 9 are provided. It goes without saying that the density and number of thin films are maintained.

The method of manufacturing the magnetic recording medium having the above structure is as follows.
It is as follows. Inorganic fine particles or organic fine particles (10 to 35 nm in diameter is desirable, but in some cases, spherical field may be used with a water-soluble polymer such as gum arabic as an adhesive on a smooth (average roughness: 4 nm) polyethylene terephthalate film having a thickness of 10 to 20 μm. Is not necessary), and is applied and fixed at a density of 3 to 30 pieces per 1 micrometer square, and Co-O, Co-Cr, Co-Ni-Ta, etc.
After forming a thin film with a thickness of 3 to 0.3 μm by an electron beam vapor deposition method, and further disposing a diamond-like hard carbon film with a thickness of 7 to 20 nm by a sputtering method, an ion beam vapor deposition method, a plasma CVD method, etc. , A polymer film with water containing warm water or alcohol, etc., adhered to a substrate such as a ferromagnetic metal thin film, an aluminum alloy obtained by polishing a laminated body of diamond-like hard carbon film, and a perfluorocarboxylic acid by a spin coating method, A magnetic recording medium is obtained by applying perfluoropolyether or the like.

The magnetic recording medium manufactured by the manufacturing method having the above-described structure will be described in detail with reference to more specific examples.

On a polyethylene terephthalate film having a thickness of 16 μm and an average surface roughness of 3 nm, SiO ₂ fine particles having a height of 120 Å are fixed with 8 to 10 [pieces / μ ² ] casein, and a rotary can (temperature: 50 cm) is placed thereon. 150-2
80 ° C.), while irradiating oxygen atoms from the minimum incident angle (27 degrees) portion, Co at an incident angle of 44 °
0.12μm by electron beam evaporation in the range of 27 to 27 degrees
Magnetic layer is formed, and the surface oxide layer is 60 to 80Å, Co ₃ O ₄
Was obtained under the condition of 94%. A 13 nm thick diamond-like hard carbon film was placed thereon by a plasma CVD method using methane gas (15 KHz; 1.22 KW), flattened by heat treatment, and cut into 3 inches. In that state, the casein was dissolved by immersing it in warm water (55 ° C.), and the laminated body of the magnetic layer and the diamond-like hard carbon film was adhered to the 1.6 mm aluminum alloy substrate with epoxy resin. A magnetic recording medium was manufactured by applying ether.

In the comparative example, a surface of a polished aluminum alloy plate was treated with an alumite coating and textured, and then a Cr underlayer of 0.15 μm was formed by a high frequency sputtering method.
Furthermore, a Co—O perpendicularly magnetized film having the same magnetic characteristics as that of the embodiment was further formed thereon by a high frequency magnetron sputtering method to 0.12
25 μm with graphite as the target
A magnetic disk having a hard carbon film of m (Comparative Example A) and 10 nm (Comparative Example B) disposed thereon and coated with 4 nm of perfluoropolyether was used. The recording linear density is 140 KFRP, the track density is 4 KTPI, and the characteristics compared with the Mn-Zn ferrite head are summarized in (Table 2).

[0023]

[Table 2]

As is clear from (Table 2), the magnetic recording medium according to the present example has an excellent effect of achieving durability and high output in high density recording in narrow track recording.

As described above, according to this embodiment, a water-soluble polymer having protrusions is arranged on a polymer film, and a laminated body of a ferromagnetic metal thin film and a hard carbon film is formed on the substrate, and The magnetic recording medium obtained by peeling the laminated body consisting of the ferromagnetic metal thin film and the hard carbon film from the substrate and adhering it to the non-magnetic substrate has the protrusions supported by the resin, and The protrusion absorbs the stress to prevent damage, and the durability can be secured even if the diamond-like hard carbon film is thinned.
It is possible to realize a magnetic recording medium in which S durability is balanced at a high level.

[0026]

As described above, according to this embodiment, a magnetic recording medium is constructed by laminating a film, a ferromagnetic metal thin film, a hard carbon film, and a lubricant layer on a non-magnetic substrate, and The polymer film absorbs the stress of the above to prevent damage and the durability can be secured even if the diamond-like hard carbon film is thinned, and high output and important CSS durability are balanced at a high level. The magnetic recording medium can be realized.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a magnetic recording medium according to a second embodiment of the present invention.

FIG. 3 is an enlarged sectional view of a conventional magnetic recording medium.

[Explanation of symbols]

 5 Non-magnetic Substrate 6 Film 7 Ferromagnetic Metal Thin Film 8 Hard Carbon Film 10 Adhesive 12 Projection 13 Micro Recess

Claims (3)

[Claims] 1. A magnetic recording medium in which a film, a ferromagnetic metal thin film, a hard carbon film, and a lubricant layer are laminated on a non-magnetic substrate. 2. A magnetic recording medium comprising a non-magnetic substrate and a laminated body of a ferromagnetic metal thin film having protrusions, a hard carbon film, and a lubricant layer bonded to each other. 3. A water-soluble polymer having protrusions is arranged on a polymer film, and a laminated body of a ferromagnetic metal thin film and a hard carbon film is formed on the substrate, and then the ferromagnetic metal thin film and the hard carbon are formed on the substrate. A method of manufacturing a magnetic recording medium, wherein a laminate composed of films is peeled off and adhered to a non-magnetic substrate.