JP2002367150A - Metal thin film type magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain downsizing of a metal thin film type magnetic recording medium without reducing the conventional mechanical strength thereof. SOLUTION: A reinforcing layer 3 the outermost surface of which has particles of average particle size a (3 nm<a<=50 nm) is interposed between a non-magnetic substrate 1 and a magnetic layer 2 of the metal thin film type magnetic recording medium 100. Thus, mechanical strength obtained by providing the reinforcing layer is remarkably enhanced so that generation of a crack on the surface of the reinforcing layer is substantially avoided and reduction of the film thickness of the metal thin film type magnetic recording medium is attained without costing the mechanical strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal thin-film magnetic recording medium, and more particularly, to a metal thin-film magnetic recording medium capable of achieving thinning without lowering its strength. The present invention relates to a metal thin film magnetic recording medium for high density magnetic recording suitable as a video tape or a large capacity tape streamer.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording tape such as an audio tape or a video tape, a magnetic powder such as an oxide magnetic powder or an alloy magnetic powder is coated on a non-magnetic support by a vinyl chloride-vinyl acetate copolymer, A so-called coating type magnetic recording medium obtained by applying and drying a magnetic paint prepared by dispersing in various binders such as polyester resin, urethane resin and polyurethane resin is widely known. With the increasing demand for high-density recording in recent years, metal magnetic materials such as Co-Ni-based alloys, Co-Cr-based alloys, and Co-O have been used for plating, vacuum evaporation, sputtering,
There has been proposed a so-called metal thin film type magnetic recording medium in which a magnetic layer is formed directly on a nonmagnetic support or via an extremely thin adhesive layer by a vacuum thin film forming technique such as an ion plating method.

[0003] Such a metal thin film type magnetic recording medium is excellent in coercive force and squareness ratio, and since the magnetic layer can be made extremely thin, it is excellent in electromagnetic conversion characteristics in a short wavelength region, and has good recording demagnetization and reproduction. The thickness loss at the time is remarkably small, and further, unlike the coating type magnetic recording medium, since the binder which is a nonmagnetic material is not mixed in the magnetic layer, various packing densities of the ferromagnetic metal particles can be increased. Has advantages.
Also, in order to improve the electromagnetic conversion characteristics and to obtain a larger output, a method of forming a magnetic layer by oblique evaporation, which is obliquely evaporated, has been proposed and put to practical use.

In the so-called metal thin film type magnetic recording medium as described above, a protective layer is formed on the magnetic layer or the main layer on the side opposite to the magnetic layer forming surface in order to improve durability and running properties. It is usual to form a back layer on the surface. Further, in the case of a metal thin-film type magnetic recording medium, the surface tends to be further smoothed in order to reduce spacing loss corresponding to high-density recording. However, when the surface of the magnetic layer becomes smooth, the contact area with the magnetic head increases, so that the frictional force increases and the shear force generated on the magnetic layer increases. In order to protect the magnetic layer from such severe sliding conditions, a protective layer may be formed on the magnetic layer.

[0005] The back layer reduces the electric resistance of the surface of the non-magnetic support, prevents running defects due to charging, improves the durability of the non-magnetic support, and generates scratches due to friction with the head during running. It has the function of protecting the magnetic tape from friction and the friction between the magnetic tapes. Conventionally, a polyethylene terephthalate film has been mainly used as a support for a metal thin-film magnetic recording medium. In particular, a polyethylene terephthalate film of about 7 to 10 μm is used as a support for a home video cassette tape, for example, an 8 mm tape, and a polyethylene terephthalate film of about 5 to 7 μm is used for a tape streamer for data backup of a computer. .

[0006]

In recent years, as for the magnetic recording media for video cassettes, with the miniaturization of the video cassettes, it is desired that the recording media be further contacted and recorded for a long time. Also, with the recent increase in the amount of information, it is desired to increase the capacity of tape streamers. To meet these demands, studies have been made to reduce the thickness of the magnetic recording medium. Especially for tape streamers, 2
The capacity is doubled every three years or so, and in order to cope with the increase in capacity, a thinner magnetic recording medium is increasingly required.

In order to reduce the thickness of the magnetic recording medium, it can be easily conceived to reduce the thickness of the support. However, when a polyethylene terephthalate film is used as the support, if the thickness is reduced, the strength in the length direction or the width direction is reduced. When the strength of the magnetic recording medium in the longitudinal direction is reduced, the magnetic recording medium is likely to be deformed when running on a video tape recorder or a drive. Also, when the magnetic recording medium has a reduced strength in the width direction, wrinkles and breaks are likely to occur,
Further, there is a problem that contact failure with the head is apt to occur. Therefore, the use of a polyethylene naphthalate film in addition to a polyethylene terephthalate film as a support for a magnetic recording medium has been studied and put to practical use.

[0008] The polyethylene naphthalate film is characterized by having a higher Young's modulus and heat resistance than a polyethylene terephthalate film. Therefore, a magnetic recording medium using this polyethylene naphthalate film as a support has a large Young's modulus as compared with a polyethylene terephthalate film, so that the thickness of the support can be reduced, and the length of the video cassette tape can be reduced. Attention has been paid to magnetic recording media that are capable of recording time and increasing the capacity of tape streamers. However, since the stiffness (hardness) is proportional to the cube of the thickness, for example, in order to obtain the same stiffness by halving the thickness of the support, the Young's modulus of the material of the support must be increased by eight times. Therefore, merely reducing the thickness of the support is insufficient in mechanical strength.

Further, polyamide films are more expensive than conventionally used polyethylene terephthalate or polyethylene naphthalate, and are not suitable for mass production and sale as a non-magnetic support material for magnetic tape.
Therefore, in view of the above problems, the present inventors have attempted to improve the recording density per unit volume by achieving a thinner magnetic layer and a thinner non-magnetic support, and to improve the mechanical strength of a magnetic tape. The present inventors have studied a metal thin-film type magnetic recording medium capable of realizing improvement at low cost, and have reached the present invention. An object of the present invention is to provide a thin metal thin film type magnetic recording medium which realizes thinning of a magnetic recording medium while maintaining the mechanical strength of the thin metal thin film type magnetic recording medium and has excellent running stability and running durability. Aim.

[0010]

According to the present invention, there is provided a metal thin film type magnetic recording medium having a magnetic layer formed on a non-magnetic support, wherein particles of the outermost surface are interposed between the non-magnetic support and the magnetic layer. A thin metal film magnetic recording medium having an average particle diameter a of 3 <a ≦ 50 nm and having a reinforcing layer made of a metal material selected from metals, metalloids and alloys, and oxides and composites thereof. It is.

Hereinafter, the present invention will be described in detail. In the present invention, the reinforcing layer having an average particle diameter a of the outermost surface particles of 3 <a ≦ 50 nm is located between the nonmagnetic support and the magnetic layer of the metal thin-film magnetic recording medium. This reinforcing layer is intended to reduce the thickness of the nonmagnetic support without substantially lowering the mechanical strength of the metal thin-film magnetic recording medium, and to reduce the size of the entire metal thin-film magnetic recording medium. That is, the conventional magnetic tape is usually made of polyester, and the non-magnetic support of the magnetic tape is usually set to a thickness of 5 to 15 μm to maintain mechanical strength and secure running stability. If the mechanical strength during running of the metal thin-film magnetic recording medium can be obtained by a method other than improving the strength of the magnetic support itself, the nonmagnetic support can be made thinner.

The presence of the reinforcing layer in the present invention is a means for obtaining a mechanical strength during running that is equal to or higher than that of the conventional one by using a thin metal film type magnetic recording medium thinner than the conventional one. Therefore, the rigidity of the reinforcing layer needs to be higher than the rigidity of the nonmagnetic support or the magnetic layer. However, according to the study of the present inventors, it is necessary to improve the mechanical strength sufficiently by simply inserting the reinforcing layer between the nonmagnetic support and the magnetic layer, in other words, to reduce the thickness of the nonmagnetic support. It was found that the average particle size of the outermost surface of the reinforcing layer greatly affected the improvement of the mechanical strength of the metal thin-film magnetic recording medium.

The relationship between the average particle size and the mechanical strength is strictly affected by the material and thickness of the non-magnetic support and the magnetic layer, and the material and thickness of the reinforcing layer itself. Range of the average particle size of the outermost surface is 3 <a ≦ 50 nm. If the average particle size is 3 nm or less, the mechanical strength of the reinforcing layer is weak, and the effect of inserting the reinforcing layer is not substantially obtained. This is because dropout increases. The average particle diameter of the particles inside the reinforcing layer can be estimated to be about 3 to 15 nm, and the average particle diameter of the particles on the outermost surface can be adjusted by increasing or decreasing the amount of oxygen supplied at the time of vapor deposition. Further, not only the average particle size but also the thickness of the reinforcing layer contributes to the improvement or maintenance of the rigidity of the nonmagnetic support. The thickness of the reinforcing layer is preferably set to 20 to 300 nm in view of improvement in rigidity and productivity, particularly 100 n.
m is preferable.

The bending rigidity of the non-magnetic support can be calculated from the Young's modulus and the thickness of the non-magnetic support. In the case where a reinforcing layer or a layer made of other various materials is formed on both sides of the non-magnetic support as well as on one side thereof, the bending rigidity and thickness of the non-magnetic support and the thickness of the layer to be formed The overall bending stiffness is calculated in consideration of the elasticity and Young's modulus. At this time, when a layer having high rigidity is formed on the outermost side, high bending rigidity can be obtained. The material constituting the reinforcing layer is Al
Besides, metals such as Cu, Zn, Sn, Ni, Ag, Co, Fe and Mn, semimetals such as Si, Ge, As, Sc, and Sb;
And their oxides can be used.

[0015] These alloys include Fe-Co, F
e-Ni, Co-Ni, Fe-Cu, Co-Cu, Co-A
u, Co-Y, Co-La, Co-Pr, Co-Gd, Co
-Sm, Co-Pt, Ni-Cu, Mn-Bi, Mn-S
b, Mn-Al, Fe-Cr, Co-Cr, Ni-Cr, F
e-Co-Cr, Ni-Co-Cr, and the like. These oxides such as metals can be easily obtained, for example, by introducing oxygen gas during vapor deposition. Compounds such as the above metals include Fe-Si-O, Si-C, Cu-Al-
O, Si-NO and Si-CO are exemplified. This reinforcing layer can be formed by a sputtering method, an ion plating method or the like in addition to the vacuum deposition, and is usually coated on a non-magnetic support, but may be coated on a magnetic layer.

According to the present invention, the thickness of the non-magnetic support for forming a thin film while maintaining the mechanical strength is desirably within a predetermined range. Since the rigidity (stiffness) of the film is proportional to the cube of the thickness, when the thickness of the nonmagnetic support exceeds a predetermined value, the mechanical strength becomes sufficient and the mechanical strength is maintained by inserting the reinforcing layer. Becomes unnecessary. When the thickness of the non-magnetic support is less than a predetermined value, the rigidity of the non-magnetic support itself is too low and the non-magnetic support constituting the metal thin-film type magnetic recording medium is added even if the rigidity is enhanced by the reinforcing layer. It is difficult to obtain sufficient rigidity for practical use. For example, when the nonmagnetic support is made of a polyester film such as polyethylene terephthalate, the preferred film thickness is 2 to 5 μm.

By providing the reinforcing layer in this manner, a metal thin film type magnetic material having a thin non-magnetic support having a thickness of 2 to 5 μm, which was conventionally realized only with an expensive and high stiffness material such as a polyamide film. The recording medium can be realized by an inexpensive material such as a polyethylene terephthalate film. The reinforcing layer is provided between the non-magnetic support and the magnetic layer. In addition, the reinforcing layer may be provided on the surface of the magnetic recording medium opposite to the magnetic layer. The mechanical strength of the body is enhanced. In this case, the mechanical strength can be improved without being substantially affected by the particle size of the outermost surface particles.

For the non-magnetic support, any known materials that can be used as ordinary magnetic tapes can be applied.
Polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytetramethylene phthalate, poly-1,4-cyclohexane dimethylene phthalate, polyethylene 2,6-naphthalenedicarboxylate, and polyethylene-p-oxobenzoate No. In particular, PET and PEN are preferable from the viewpoint of easy availability of materials and good workability. These polyesters may be homopolyesters or copolyesters.

The magnetic layer is coated on the reinforcing layer, or after the magnetic layer is coated with the reinforcing layer, and then integrated with the non-magnetic support. The material of the magnetic layer is a ferromagnetic metal material. As the ferromagnetic metal material, any of known metals and alloys can be used. For example, a ferromagnetic metal such as Fe, Co and Ni, CoN
i, FeCo, FeCoNi, FeCu, CoCu, CoA
u, CoPt, MnBi, MnAl, FeCr, CoCr, N
iCr, FeCoCr, CoNiCr and FeCoNiC
r and other ferromagnetic alloy materials. This magnetic layer may be a single-layer film or a multilayer film of the ferromagnetic metal material. In the case of a multilayer film, an intermediate layer of Cr or the like may be formed between the metal magnetic thin films in order to improve the adhesion between the layers and control the coercive force.

The vicinity of the surface of the magnetic layer may be converted to an oxide in order to improve corrosion resistance and the like. This magnetic layer
A vacuum evaporation method in which a ferromagnetic material is heated and evaporated in a vacuum and attached to a non-magnetic support, an ion plating method in which a ferromagnetic metal material is evaporated in a discharge, and a glow in an atmosphere containing argon as a main component. It can be formed by a so-called PVD technique such as a sputtering method in which atoms on the target surface are beaten by argon ions generated by the discharge. The protective layer that can be formed on the upper surface of the magnetic layer has a function of ensuring good corrosion resistance and running durability. The protective layer forming material is
Known materials generally used as a protective layer for a metal magnetic thin film can be used, for example, carbon, CrO ₂ , Al ₂ O
_3, BN, Co _{oxide, MgO, SiO 2, Si 3} O 4, SiN
_{x, SiC, SiNx-SiO 2} , ZrO 2, TiO 2, Ti
C, MoS, and the like.

This protective layer can be formed by a known vacuum film forming technique such as a CVD method. This CVD method
Hard carbon called diamond-like carbon, which has excellent wear resistance, corrosion resistance and surface coverage, has a smooth surface shape and high electrical resistance, is a technology that decomposes carbon compounds in plasma and forms a film. Can be formed stably to a thickness of In this case, as the carbon compound, known materials such as hydrocarbons, ketones, and alcohols can be used. Also, a high frequency bias voltage is used for decomposition in the plasma. Further during the plasma generation, as a gas for promoting the decomposition of the carbon compound may be introduced Ar and H _2.

In order to improve the film hardness and corrosion resistance of diamond-like carbon, carbon may be in a state of reacting with nitrogen or fluorine. The diamond-like carbon film may be a single layer or a multilayer. Is also good. At the time of plasma generation, a film such as a gas such as N ₂ , CHF ₃ , CH ₂ F ₂ or the like may be used alone or in an appropriate mixture in addition to the carbon compound. If the protective layer is too thick, the loss due to spacing increases, and if it is too thin, the abrasion resistance and corrosion resistance deteriorate. Therefore, it is desirable to form the protective layer to a thickness of about 4 to 15 nm.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the metal thin film type magnetic recording medium according to the present invention will be described with reference to the accompanying drawings. FIG. 1A is a schematic longitudinal sectional view showing one embodiment of a metal thin film magnetic recording medium according to the present invention, and FIG. 1B is a schematic longitudinal sectional view showing another embodiment of the same. In the metal thin-film magnetic recording medium 100 of the embodiment shown in FIG. 1A, the upper surface of the nonmagnetic support 1 made of a polyester resin such as polyethylene terephthalate having a thickness of about 2 to 5 μm
A metal reinforcing layer 3 having a thickness of 300 nm is covered by vacuum evaporation or the like. It is desirable to coat the upper surface of the reinforcing layer 3 with a lubricant or a rust inhibitor. As the lubricant to be used, those generally used for magnetic tape applications can be used. Particularly, the skeleton is preferably a fluorocarbon-based, alkylamine-based or alkylester-based skeleton.

A magnetic layer 2 made of a ferromagnetic metal material is coated on the reinforcing layer 3, and a protective layer 4 is further coated on the magnetic layer 2. The lower surface of the non-magnetic support 1 is desirably coated with the above-described coating. The back surface of the non-magnetic support 1 is coated with, for example, a polyurethane-based back coat paint to form a back layer. 5 are formed. In this metal thin-film magnetic recording medium 100, the reinforcing layer 3 sandwiched between the non-magnetic support 1 and the magnetic layer 2 improves the mechanical strength of the entire metal thin-film magnetic recording medium 100. The thickness of the non-magnetic support 1 can be made thinner than before without reducing the strength, and thus the overall size of the metal thin-film magnetic recording medium can be reduced.

In a metal thin film type magnetic recording medium 100A according to another embodiment shown in FIG. 1B, a reinforcing layer 3A is inserted between the nonmagnetic support 1 and the back layer 5 in addition to the reinforcing layer 3 of FIG. 1A. It is. In this embodiment, since the nonmagnetic support 1 is sandwiched between the pair of reinforcing layers 3 and 3A, the mechanical strength of the nonmagnetic support 1 is further improved, in other words, the thickness of the nonmagnetic support 1 is reduced. It can be thinner.

Next, an example of a vapor deposition device 10 that can form a magnetic recording medium for forming the magnetic layer 2 of the metal thin-film type magnetic recording medium 100 will be described with reference to FIG. In the vapor deposition apparatus 10, a feed roll 13 and a take-up roll 14 are provided in a vacuum chamber 11 evacuated from exhaust ports 21 and 22 to be in a vacuum state. Are sequentially driven. A cooling can 15 is provided between the feed roll 13 and the take-up roll 14 while the nonmagnetic support 1 is running. This cooling can
A cooling device (not shown) is provided at 15 to suppress thermal deformation and the like due to a temperature rise of the non-magnetic support 1 running on the peripheral surface.

The non-magnetic support 1 is sequentially sent out from a feed roll 13, passes through the peripheral surface of a cooling can 15, and is taken up by a take-up roll 14. A predetermined tension is applied to the non-magnetic support 1 by the guide rolls 16 and 17, so that the non-magnetic support 1 runs smoothly. A crucible 18 is provided below the cooling can 15 in the vacuum chamber 11, and the crucible 18 is filled with a magnetic metal material 19. On the other hand, on the side wall of the vacuum chamber 11, an electron gun 20 for heating and evaporating the metal magnetic material 19 filled in the crucible 18 is provided. The electron gun 20 is arranged at a position where the electron beam B emitted thereby irradiates the metal magnetic material 19 in the crucible 18. And this electron beam B
Is applied to the surface of the non-magnetic support 1 to form the magnetic layer 2.

In the vicinity of the cooling can 15 between the cooling can 15 and the crucible 18, a shutter 23 is arranged so as to cover a predetermined area of the nonmagnetic support 1 running on the peripheral surface of the cooling can 15, The metal magnetic material 19 evaporated by the shutter 23
Is obliquely deposited on the non-magnetic support 1 within a predetermined incident angle range. Further, when the magnetic layer 2 is deposited, oxygen gas is supplied to the surface of the non-magnetic support 1 by an oxygen gas introducing pipe 24 provided through the side wall of the vacuum chamber 11 so that the magnetic layer 2 Are improved in magnetic properties, durability and weather resistance. On the magnetic layer 2,
Usually, a protective layer 4 is required to ensure good corrosion resistance and running durability.
Are formed.

Although the procedure for forming the protective layer 4 has been described using the apparatus shown in FIG. 2, the reinforcing layer 3 may be formed using the apparatus shown in FIG. The crucible 18 is filled with a metal material constituting the reinforcing layer 3, for example, Al. The crucible 18 is irradiated with an electron beam B from an electron gun 20, and oxygen is introduced to thereby evaporate Al
An oxide of a metal material such as is adhered to the surface of the nonmagnetic support 1 to form the reinforcing layer 3. The above-mentioned protective layer 4 can be formed by a known vacuum film forming technique, and can be formed by a CVD method using, for example, a plasma CVD continuous film forming apparatus shown in FIG. 3 in addition to the apparatus shown in FIG. Plasma CV shown in FIG.
In the D continuous film forming apparatus 300, a feed roll 333 and a take-up roll 334 are provided in a vacuum chamber 331 that has been evacuated and evacuated from an evacuation system 330.
An object to be processed 340 having a magnetic layer formed on a non-magnetic support is run sequentially. A cylindrical rotatable counter electrode can 335 is provided while the object 340 is running from the feed roll 333 to the take-up roll 334.

The object to be processed 340 is sequentially sent out from the feed roll 333, passes through the peripheral surface of the opposing electrode can 335, and is taken up by the take-up roll 334. In addition, between the feed roll 333 and the counter electrode can 335,
Guide rolls 336 are arranged between the can 335 for counter electrode and the take-up roll 334, respectively.
Is applied with a predetermined tension so that the object to be processed 340 runs smoothly. A reaction tube 337 made of, for example, Pyrex (registered trademark) glass, plastic, or the like is provided below the counter electrode can 335.

The reaction tube 337 has an end penetrating through the bottom of the vacuum chamber 331, and a film forming gas is introduced into the reaction tube 337 from a discharge gas inlet 341 at the end. . An electrode 3 made of a metal mesh or the like is provided in the reaction tube 337.
38 are incorporated. This electrode 338 has a predetermined potential, for example, 500 to 2000 by a DC power supply 339 provided outside.
A voltage of V is applied. In the plasma CVD continuous film forming apparatus 300 having the above-described configuration, when a voltage is applied to the electrode 338, the electrode 338 and the counter electrode can 3
A glow discharge occurs between the glow discharge and the glow discharge. Then, the film forming gas introduced into the reaction tube 337 is decomposed by the generated glow discharge, and is deposited on the object to be processed 340. Although the film formation of the protective layer 4 by the apparatus of FIG. 3 has been described, the film may be formed by a magnetron sputtering apparatus shown in FIG.

In the magnetron sputtering apparatus 400 shown in FIG. 4, a supply roll 439 and a take-up roll 440 are provided in a chamber 431 that has been evacuated by a vacuum pump 432. An object 450 having a magnetic layer formed on a non-magnetic support is configured to run sequentially. While the object 450 is running on these rolls 439 and 440, a cylindrical rotatable cooling can 435 is provided. In addition, between the supply roll 439 and the cooling can 435, and between the cooling can 435 and the take-up roll.
Guide rolls 441 are arranged between 440 and
A predetermined tension is applied to the target object 450 so that the target object 450 runs smoothly.

At a position facing the cooling can 435 in the chamber 431, a target 436 is provided. The target 436 is a material for the protective layer 4 and is made of, for example, carbon. The target 436 is supported by a backing plate 437 that constitutes a cathode electrode, and a magnet 438 that forms a magnetic field is provided on the back surface of the backing plate 437. When forming the protective layer 4 using this magnetron sputtering apparatus 400,
After the pressure in the chamber 431 is reduced to about 10 ^-4 Pa by the vacuum pump 432, the valve 433 is evacuated to the vacuum pump 432 side.
To control the pumping speed. A from gas introduction pipe 434
The degree of vacuum is set to, for example, about 0.8 Pa by introducing r gas.

Then, an Ar gas is introduced from the gas introduction pipe 434, a voltage of about 3000 V is applied using the cooling can 435 as an anode and the backing plate 437 as a cathode, and a state in which a current of about 1.4 A flows is maintained. Then, by this voltage application, Ar gas is turned into plasma, and the ionized ions collide with the target 436, whereby atoms are ejected from the respective materials. At this time, a magnetic field is formed in the vicinity of the target 436 by the magnet 438 arranged on the back surface of the backing plate 437, so that the ionized ions are concentrated near the target 436.

The atoms ejected from the target 436 are fed out of the magnetic tape roll in the direction of the arrow shown in the figure, and run along the outer peripheral surface of the cooling 435.
Adheres to The object 450 on which the protective layer 4 has been formed in this manner is taken up by a take-up roll 440.

[0036]

EXAMPLES Next, examples and comparative examples relating to the metal thin film type magnetic recording medium according to the present invention will be described, but these do not limit the present invention.

(Preparation of Metal Thin Film Magnetic Recording Medium) As a non-magnetic support of the metal thin film magnetic recording medium shown in FIG.
A polyethylene terephthalate film having a thickness of 4 μm and a width of 150 mm was prepared. Using the vapor deposition apparatus shown in FIG. 2, a reinforcing layer was formed on a nonmagnetic support under the following vapor deposition conditions while introducing oxygen by a vacuum vapor deposition method.

(Evaporation conditions) Metal magnetic material: Al (aluminum) 100% by weight Incident angle: 45 ° to 10 ° Introduced gas: oxygen gas Oxygen introduction amount: 0 to 1.0 SLM Vacuum degree during evaporation: 2.0 × 10 ⁻² Pa Reinforcement layer thickness: 100 nm

Next, a magnetic layer was formed on the reinforcing layer using the vapor deposition apparatus shown in FIG. 2 under the following vapor deposition conditions. (Evaporation conditions) Metal magnetic material: 100% by weight of Co (cobalt) Incident angle: 45 ° to 10 ° Introduced gas: oxygen gas Oxygen introduction amount: 3.3 × 10 ⁻² m ³ / sec Vacuum degree during evaporation: 2.0 × 10 ^{− 2} Pa thickness of magnetic layer: 160 nm

Next, a diamond-like carbon protective layer was formed on the magnetic layer by a plasma CVD method under the following conditions for forming the protective layer. (Protective layer deposition conditions) Reactive gas: toluene Reactive gas pressure: 10 Pa Introduced power: DC current 1.5 kV Thickness of protective layer: 10 nm

Next, a lubricant was applied to the surface opposite to the surface on which the magnetic layer was formed. The lubricant used was "Demtam", a trade name of Daikin Industries, Ltd., whose main skeleton is fluorocarbon.
Is modified with a tertiary amine, dimethyldecylamine,
It was synthesized to have a salt structure. On the applied lubricant, a polyurethane-based back coat paint as a back material was applied to a thickness of 0.5 μm by a gravure roll method. Finally, the obtained metal thin film type magnetic recording medium was cut into a width of 6.35 mm, and a perfluoroether-based lubricant was applied to the surface of the magnetic layer to prepare a sample magnetic tape.

In the following Examples 1 to 3 and Comparative Examples 1 and 2, the amount of oxygen introduced during the formation of the reinforcing layer was changed to prepare magnetic tapes of samples in which the fine particles on the outermost surface of the reinforcing layer had different particle diameters. The other conditions were as described above. FIG. 5 shows an 80,000-fold scanning probe micrograph of the reinforcing layer of the magnetic tape of the sample obtained in Example 2.

Example 1 Oxygen introduction amount: 1.0 SLM Average particle size of fine particles: 20 nm

Example 2 Oxygen introduction amount: 0.6 SLM Average particle size of fine particles: 40 nm

Example 3 Oxygen introduction amount: 0.4 SLM Average particle size of fine particles: 50 nm

Comparative Example 1 Oxygen introduction amount: 3.0 SLM Average particle size of fine particles: 3 nm

Comparative Example 2 Oxygen introduction amount: 0 SLM Average particle size of fine particles: 60 nm

Comparative Example 3 A non-magnetic support having a thickness of 6 μm was prepared without forming a reinforcing layer.

Various physical properties and characteristics of the samples of Examples 1 to 3 and Comparative Examples 1 to 3 thus manufactured were measured as follows, and the obtained results are summarized in Table 1. As can be seen from Table 1, in Examples 1 to 3, the mechanical strength (Young's modulus) was improved by forming the reinforcing layer between the non-magnetic support and the magnetic layer, and the tape machine when using the thin non-magnetic support was used. Deterioration per head due to reduced strength, shuttle durability and still durability have been improved.

On the other hand, in Comparative Example 1 in which the average particle size of the fine particles was 3 nm, the effect of the provision of the reinforcing layer was not observed, and the mechanical properties of the magnetic tape were reduced, and the head contact was deteriorated.
The results of Comparative Example 1 show that the average particle size of the fine particles on the outermost surface of the reinforcing layer needs to be larger than 3 nm.
In Comparative Example 2 in which the average particle size of the fine particles is 60 nm, it can be seen that the particles on the outermost surface of the reinforcing layer are too large, cracks are generated on the surface of the magnetic layer, and the dropout is deteriorated. The results of Comparative Example 2 indicate that the average particle size of the fine particles on the outermost surface of the reinforcing layer needs to be less than 60 nm. In Comparative Example 3 in which the reinforcing layer was not formed, the mechanical properties of the magnetic tape were reduced, and the head contact was deteriorated.

[0051]

[Table 1]

Average particle size of fine particles on the outermost surface of the reinforcing layer The surface shape was observed and measured using a scanning probe microscope manufactured by Shimazu Corporation. Using a Young's modulus tensile strength tester, one end of a sample having a length of 100 mm was fixed, and another end was pulled at a pulling speed of 100 mm / min, and the load when the sample was elongated by 0.5% was measured. In the table, MD is a value in the length direction of the tape, and TD is a value in the width direction of the tape.

Evaluation of characteristics of magnetic recording medium DV deck DHR-1000 (trade name) manufactured by Sony Corporation
This was performed using a modified version. The dropout of 50 μs was counted for 10 minutes.

Contact Characteristics with Head The minimum value / maximum value (%) of the output signal (hit waveform) at the time of tape reproduction for one track was measured. Shuttle durability The amount of level reduction after 100 runs was measured. Still durability When the mode was changed to the still mode, the time until the output dropped by 3 dB was measured.

[0055]

According to the present invention, there is provided a metal thin-film type magnetic recording medium having a magnetic layer formed on a non-magnetic support, wherein an average particle diameter a of particles on the outermost surface is provided between the non-magnetic support and the magnetic layer. Is 3
<A ≦ 50 nm, and a metal thin-film magnetic recording medium characterized by having a reinforcing layer made of a metal material selected from metals, metalloids and alloys, and oxides and composites thereof. The average particle diameter a of the outermost surface particles is 3 <a ≦ 50n
When the reinforcing layer having a thickness of m is provided between the nonmagnetic support and the magnetic layer, the effect of improving the mechanical strength by the provision of the reinforcing layer is remarkably exhibited, and cracks can be substantially prevented from being generated on the surface of the reinforcing layer. It is possible to provide a metal thin-film magnetic recording medium capable of achieving a thin film without lowering the strength. If a reinforcing layer is provided on the other side of the non-magnetic support in addition to the space between the non-magnetic support and the magnetic layer, the non-magnetic support is sandwiched between the pair of reinforcing layers, thereby improving the mechanical strength. Becomes more noticeable.

[Brief description of the drawings]

FIG. 1A is a schematic longitudinal sectional view showing one embodiment of a metal thin film magnetic recording medium according to the present invention, and FIG. 1B is a schematic longitudinal sectional view showing another embodiment of the same.

FIG. 2 is a longitudinal sectional view showing an example of a vapor deposition apparatus that can be used for forming a magnetic layer and a reinforcing layer of a metal thin-film magnetic recording medium.

FIG. 3 is a longitudinal sectional view showing an example of a plasma CVD continuous film forming apparatus that can be used for forming a protective layer of a metal thin film type magnetic recording medium.

FIG. 4 is a longitudinal sectional view showing an example of a magnetron sputtering apparatus which can be used for forming a protective layer of a metal thin film type magnetic recording medium.

FIG. 5 is a diagram showing the surface state of the reinforcing layer produced in Example 2.
10,000 times scanning probe micrograph.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic support, 2 ... Magnetic layer, 3 and 3A ... Reinforcing layer, 4 ... Protective layer, 5 ... Back layer, 100, 100A ... Metal thin film type magnetic recording medium.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Kanagawa 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Yoshisumi Suzuki 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5D006 BB01 CA00 CA05 CB01 CC00 DA00

Claims (5)

[Claims] 1. In a metal thin-film magnetic recording medium having a magnetic layer formed on a non-magnetic support, an average particle diameter a of the outermost surface particles is 3 <a between the non-magnetic support and the magnetic layer. ≤50n
m, a metal thin-film magnetic recording medium comprising a reinforcing layer made of a metal material selected from metals, metalloids and alloys, and oxides and composites thereof. 2. The metal thin-film magnetic recording medium according to claim 1, wherein the nonmagnetic support is a polyester film, and the thickness thereof is 2 μm or more and 5 μm or less. 3. The metal thin-film magnetic recording medium according to claim 1, wherein the thickness of the reinforcing layer is 20 nm or more and 300 nm or less. 4. The metal thin-film magnetic recording medium according to claim 1, further comprising a protective layer outside the magnetic layer and a back layer outside the nonmagnetic support. 5. A metal thin-film magnetic recording medium having a magnetic layer formed on a non-magnetic support, wherein a metal or a semi-metal is provided between the non-magnetic support and the magnetic layer and on the other side of the non-magnetic support. And a metal thin-film magnetic recording medium having a reinforcing layer made of a metal material selected from the group consisting of a metal, an alloy, and an oxide and a composite thereof.