JPH0668446A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the magnetic recording medium with which recording and reproducing can be executed by a narrow gap ring type magnetic head improved in magnetic saturation by solving the unbalance between the reliability and electromagnetic conversion characteristics of the magnetic recording medium formed with a ferromagnetic metallic film as a magnetic layer of a magnetic tape to be used for magnetic recording and reproducing apparatus. CONSTITUTION:A vapor deposited layer 7 consisting of columnar particles is disposed on a high-polymer film 6. The magnetic recording layer and a cleaning layer are formed continuously so that the directions of respective columnar particles are varied. As a result, the magnetic recording medium with which the high-density recording and reproducing are repetitively executed while the surface for sliding with a head is maintained in a good state 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. Development of magnetic tapes is becoming popular. Although many proposals have been made, magnetic recording media such as magnetic tapes and magnetic disks having a magnetic layer of a ferromagnetic metal thin film typified by a Co—Ni—O oblique deposition film and a Co—O perpendicular magnetization film are promising. is there. The conventional magnetic tape will be described below. FIG. 3 shows an enlarged cross section of a conventional magnetic tape. In FIG. 3, reference numeral 1 denotes a polymer film such as polyethylene terephthalate or polyethylene naphthalate, and a so-called fine particle coating layer in which inorganic ultrafine particles such as SiO ₂ , Al ₂ O ₃ or organic ultrafine particles such as polyimide or polyester are dispersed and applied. Often used. Two
Is C formed by oblique vapor deposition with a continuously changing incident angle
a single or multi-layered ferromagnetic metal thin film of o-Ni-O,
Oblique vapor deposition (often assisted by ions) film of Fe in N ₂ gas or ammonia gas, Co-Cr, Co-O
A magnetic layer such as a perpendicular magnetization film formed by tilted vapor deposition of 3 is a protective film such as an oxide film, a nitride film, and a plasma polymerization film, 4 is a fatty acid,
A lubricating layer made of fluorine oil or the like, and 5 is a back coat layer having good smoothness, which is often seen in thin magnetic tapes.
The operation of the magnetic tape having the above structure will be described below. For example, a long magnetic tape is stored as it is stored in a cassette, and when access is required, a part of the cassette is unsealed and pulled out.
It moves at a constant speed and is used for recording and playback. The magnetic tape is pulled out by a ring-type magnetic head mounted on a rotating cylinder that rotates at high speed to convert an electric signal into a residual magnetization pattern, which is then recorded on the magnetic layer and reproduced by reverse conversion. Since the principle is used, it is required to endure repeated sliding to secure a high-speed relative speed between the magnetic head and the tape. Therefore, various protective lubrication systems have been proposed for the purpose of mitigating friction with a sliding partner in order to prevent adhesive wear of a magnetic layer made of a ferromagnetic metal thin film. Among them, a carbon film having an increased hardness (Japanese Patent Laid-Open No. 53-1430).
No. 26) has attracted attention, and an amorphous carbon film is provided through a SiO ₂ film in order to improve the adhesion with a ferromagnetic metal thin film and to improve the still durability as a video tape ( Japanese Patent Laid-Open No. 61-242323
Japanese Patent Laid-Open No. 64-79932, which has an amorphous carbon film disposed through an organic plasma polymerized film (Japanese Patent Application Laid-Open No. 62-167616), and which has a carbon film disposed through a boron carbide film. Etc. have been proposed. The one with such improvements is also used in combination with many magnetic recording / reproducing devices, so that different materials are burned on the sliding surface of the magnetic head, and the step between head constituent materials is recorded or reproduced. Since either or both of them cause a problem that the converted signal output is lowered, a method of rejuvenating the sliding surface of the magnetic head by a so-called magnetic head cleaning tape having a high polishing force is adopted.

[0003]

However, the rejuvenation by the magnetic head cleaning tape is not always sufficient for the recovery of the recording / reproducing characteristics of the ring type magnetic head having a narrow gap, and the S / N ratio in the short wavelength region in magnetic recording. There was a problem that it would be difficult to secure. The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic tape which enables high density recording in a narrow track and which can stably obtain durability and high output characteristics.

[0004]

In order to achieve this object, the magnetic tape of the present invention has a structure in which a cleaning layer and a magnetic recording layer are continuous, and the directions of columnar particles of the cleaning layer and the magnetic recording layer are different. Have

[0005]

According to this structure, the head surface is revived while the magnetic head surface is little changed by the cleaning layer at the start end or the end when the magnetic tape is used, so that the S / N ratio in high density recording can be secured. It will be easier. Further, since the cleaning layer is configured so that the direction of the columnar particles is different from that of the magnetic recording layer, the contact state between the head and the tape hardly changes, but the polishing property is opposite to that of the magnetic recording layer due to the different crystal planes. The head surface can be revived in a sufficiently short time.

[0006]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 6 is a polymer film of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, aramid, polyimide, etc., which has fine irregularities formed by internal particles as necessary, has a fine particle coating layer, or has two layers. It may have a composite structure formed by extrusion, and the thickness is 3 to 10 μm.
Within this range, the surface roughness and mechanical strength may be appropriately set to values obtained by optimization studies. Reference numeral 7 denotes a vapor-deposited layer composed of columnar particles, in which the angles of the growth directions of the columnar particles with respect to the film surface of the magnetic recording layer portion A and the cleaning layer portion B are different from each other, and the layer C is a transition portion. The direction of the columnar particles is such that the direction of the columnar particles in the cleaning layer portion B is set depending on, for example, the recording layer portion A formed by oblique vapor deposition or the vapor deposition with almost vertical components. Both layers may have a laminated structure. Needless to say, in order to complete the magnetic recording medium, the protective lubricating layer, the back coat layer and the like can be provided by a conventionally known technique.

The effects of the present embodiment will be clarified below by further comparing the specific example with the conventional example. A polyethylene terephthalate film having a thickness of 8 μm, a Young's modulus of 550,590 [kg / mm ² ] in the longitudinal direction and a width direction of 7 to 10 [pieces / μ ² ] with a height of 160Å, and a cooling can with a diameter of 50 cm. While moving along with, 90 degrees from the minimum incident angle 25 degrees (Tape A), 42 degrees (Tape B),
Co (99.99% purity) Co was vapor-deposited by 0.24 μm in the range up to 60 degrees (Tape C). Oxygen gas is introduced from the inside of the shield that limits the minimum incident angle during vapor deposition,
The magnetic recording layer and the cleaning layer are switched by the movement of the shield, and both start vapor deposition in the opposite incident direction.
Deposition was completed at 33 degrees, and the amount of oxygen introduced was increased so that the cleaning layer became non-magnetic. However, the film thickness was the same as that of the magnetic recording layer. Further, commonly, a hard carbon film is formed by a sputtering method to 100 Å, about 30 Å perfluoropolyether as a lubricant is arranged, a 0.4 μm back coat layer is arranged, and smoothing treatment is applied to an 8 mm wide magnetic tape. processed. Each of the high-band 8 mm video was modified to include a metal-in-gap type magnetic head (head a) in which a sendust sputter film with a gap length of 0.18 μm was arranged near the gap, and a Co-based amorphous alloy film with a thickness of 0.17 μm was Si.
Recording and reproduction were repeated under the recording conditions of a recording wavelength of 0.46 μm and a track pitch of 9 μm using a laminated magnetic head (head b) laminated with an O ₂ film interposed therebetween. In the conventional example, the cleaning layer was separated and wound into a cassette, and a commercially available cleaning tape was used as the cleaning tape.

The length of the magnetic tape was 120 m, and 6 rolls were randomly selected and displayed as an average value of 6 rolls. The characteristics of the magnetic recording medium according to this example and the characteristics of the conventional magnetic recording medium are shown in comparison with (Table 1).

[0009]

[Table 1]

As is clear from (Table 1), the magnetic recording medium according to the present embodiment has an excellent effect that it is possible to realize durability and a high S / N ratio in high density recording in narrow track recording. .

As described above, according to this embodiment, the cleaning layer and the magnetic recording layer are continuous with each other, and the direction of the columnar particles of the cleaning layer and the magnetic recording layer are different from each other, whereby the magnetic head slides. The surface can be maintained in a good state, and an excellent S / N ratio can be realized in high density recording.

(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 main part of a magnetic tape showing a second embodiment of the present invention.
In FIG. 2, reference numeral 8 denotes a polymer film which may be a polyethylene terephthalate, polyethylene naphthalate, aramid film or the like having fine irregularities due to internal particles. Reference numeral 9 is a fine particle coating layer in which ultrafine particles such as SiO ₂ and polysulfone are dispersed, which is obtained by stretching the film after coating the particles to transform the coating into a mountain range or by utilizing the difference in evaporation rate of the mixed solvent. It is also possible to use the obtained one having similar irregularities. Reference numeral 10 is a thin film, and the magnetic recording layer portion A has a film thickness of t ₁ and is composed of a ferromagnetic composition such as Co—O or Co—Ni—O. It has a protrusion 11 that is determined by the conditions. The cleaning layer portion B has a film thickness t ₂ , and the ratio of t ₂ to t ₁ is preferably in the range of 1.5 to 3 times. If it is 1.5 times or less, the polishing action is weak as described later, and the restriction of 3 times is due to the characteristics and manufacturing. If it is 3 times or more, the mechanical strength of the thin film becomes too strong and the sliding surface of the magnetic head becomes This is because the flattening has an adverse effect on the output during reproduction. The cleaning layer portion B can be selected not only as to thickness but also as to whether or not it has magnetism by changing the oxygen introduction conditions and masking position. However, when viewed from the tape usage, a more transparent oxide state optically detects the start and end. It is preferable for control. However, the range of implementation is not limited to that, and even with respect to the uniformity of the film thickness, the basic operational effect can be secured even if the film thickness is inclined within the above range, and strict control is not necessary in this respect as well. is there. The components other than those described above, such as the protective lubricating layer and the back coat layer, can be widely selected, including those described in Example 1.

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

An average of 25 ultrafine particles of SiO ₂ having an average particle diameter of 150Å were arranged on a polyimide film having a thickness of 5 μm on an average of 25 / μ ² and a Co—Cr (CR; 21 atomic%) perpendicular magnetization film was used as a magnetic recording layer. 2μ is formed, the transition part is 1cm, and the cleaning layer is 0.3μm of Co-C of the same composition.
r film (tape 2A), 0.4 μm Co—Cr film of the same composition (tape 2B), and a magnetic recording layer along a rotating can (20 ° C.) with a diameter of 1 m.
Saturation magnetic flux density of the magnetic recording layer was increased by increasing the amount of oxygen as a cleaning layer by electron beam vapor-depositing Co in an oxygen atmosphere in an incident angle range of 0 degrees to a minimum of 40 degrees to form a 0.1 μm Co-O layer. Almost half of the Co-O film is 0.15
We arrange μm (tape 2C), 0.3μm (tape 2D),
A diamond-like hard carbon film was placed 140 Å on each of the graphite targets by the high frequency magnetron sputtering method, and perfluorostearic acid was further added in a dry thickness conversion of 4
It is applied by the solution application method so that it becomes 0Å, and 0.4 μm
The magnetic tape having a width of 8 mm was prepared by arranging the back coat layer. As a comparative example, a tape having the same structure as the tapes 2C and 2D was prepared except that a cleaning layer was a Co—O layer having a thickness of 0.4 μm. For the evaluation, a metal-in-gap type magnetic head (head a) in which a 8 mm video was modified and a sendust sputtered film with a gap length of 0.15 μm was arranged near the gap,
Laminate type magnetic head (head b) in which 0.14 μm Co-based amorphous alloy films are laminated via a SiO ₂ film
Recording wavelength 0.43 μm, track pitch 9 μ
Recording and reproduction were repeated under the recording condition of m. In the conventional example, an independent cleaning tape was used in combination with a magnetic tape, and a commercially available cleaning tape was used. The length of the magnetic tape was 120 m, and 6 rolls were randomly selected and displayed as an average value of 6 rolls. The characteristics of the magnetic recording medium according to this example and the characteristics of the conventional magnetic recording medium are shown in comparison with each other (Table 2).

[0015]

[Table 2]

As is clear from (Table 2), the magnetic recording medium according to the present embodiment can repeatedly use signals with few errors in high density recording.

As described above, according to this embodiment, the cleaning layer and the magnetic recording layer are continuous with each other, and the protrusion of the cleaning layer portion is formed larger than the protrusion of the magnetic recording layer portion by increasing the film thickness. The slidable surface can be efficiently polished and maintained in a good state, an excellent S / N ratio can be realized in high density recording, and recording / reproduction can be repeated with a good error.

Although the first and second embodiments are both magnetic tapes, they may be magnetic disks, in which case either the inner peripheral surface side or the outer peripheral surface side adjacent to the recording portion or It suffices to dispose the polishing portions on both sides, and in that state, excellent recording characteristics and high durability in high density recording can be obtained in a well-balanced manner regardless of whether it is hard or flexible.

[0019]

As described above, according to the present invention, the cleaning layer and the magnetic recording layer are continuous with each other, and the direction of the columnar particles of the cleaning layer and the magnetic recording layer are different from each other. It is possible to realize a magnetic recording medium capable of maintaining an excellent moving surface and supplying an excellent S / N ratio in high density recording.

[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]

 7 Vapor Deposition Layer Composed of Columnar Particles 9 Fine Particle Coating Layer 10 Thin Film 11 Protrusion

Claims (2)

[Claims] 1. A magnetic recording medium in which a cleaning layer and a magnetic recording layer are continuous and the directions of columnar particles of the cleaning layer and the magnetic recording layer are different. 2. A magnetic recording medium in which a cleaning layer and a magnetic recording layer formed on a substrate having granular projections are continuous, and the thickness of the cleaning layer is larger than that of the magnetic recording layer.