JPH07244841A - Magnetic recording medium, method and apparatus for manufacturing the medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium whose electrical conducting properties and running properties are improved and, further, which does not have a harmful warpage causing the deterioration of recording/reproducing. CONSTITUTION:A first metal magnetic film is provided on one of the surfaces of a supporter and a second metal magnetic film is provided on the other surface. The second metal thin film is composed of the deposited particles whose diameters are 5-100nm and its surface roughnesses Ra and Rz are 5-30nm and 80-400nm respectively.

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 type magnetic recording medium.

[0002]

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes are of a coating type in which a magnetic coating in which a magnetic powder or a binder is dispersed in a solvent is coated on a film which is a non-magnetic support.
There is a metal thin film type in which metal magnetic particles are deposited on a film without using a binder.

Among these, the metal thin film type magnetic recording medium is said to be suitable for high-density recording because the magnetic layer does not contain a binder and therefore has a high packing density of the magnetic material. By the way, the metal thin film magnetic recording media currently on sale or under development have the structure shown in FIG. In FIG. 2, 31 is a polyethylene terephthalate (PET) film having a thickness of 2 to 50 μm, and 32 is
For example, the thickness is 1500Å which is constructed by vacuum deposition method.
Is a Co-Ni (80% -20%) alloy magnetic film, 33 is a lubricant film, and 34 is a back coat layer. The back coat layer 34 is prepared by dispersing carbon black having a particle diameter of 10 to 100 nm and a binder resin in a paint, and using a gravure method, a reverse method or a die coating method, and a thickness after drying is 0.5. It is constituted by applying so as to have a thickness of ˜1 μm.

Here, the role of the back coat layer is as follows. (1) By having conductivity, antistatic is achieved,
Prevents adhesion of dust. (2) Surface stability (coefficient of friction) is improved to obtain running stability. (3) The front magnetic layer and the back magnetic layer are balanced to prevent warpage. Thus, even in the metal thin film type magnetic recording medium, the back coat layer is still a coating type.

By the way, when the back coat layer is first applied and then the magnetic layer is vacuum-deposited, degassing (generated from the solvent of the binder) is generated from the back coat layer in a vacuum system, the degree of vacuum is lowered, and vapor deposition is carried out. It does not work well, the magnetic film cannot be formed well, and a high-performance magnetic recording medium cannot be obtained.
Therefore, after forming the magnetic film in a vacuum, the magnetic film is taken out into the atmosphere and the back coat layer is applied.

However, this method has a problem that in the step of applying the back coat layer, the magnetic layer becomes dirty or dust is attached to increase the dropout.
Further, although the conductivity of carbon black is good, there is also a problem that the conductivity is lowered due to the large amount of binder and the antistatic effect is low.

[0007]

DISCLOSURE OF THE INVENTION In view of the above points, it has been attempted to form the back coat layer with a metal thin film like the metal thin film type magnetic layer. However, the metal thin film formed by the dry plating means such as the vacuum vapor deposition method (1) has conductivity to prevent the electrification,
Prevents adhesion of dust. (3) The front magnetic layer and the back magnetic layer are balanced to prevent warpage. However, (2) Surface property (friction coefficient) is improved and running stability is obtained. On the contrary, the features are worse, and they are never satisfactory.

For example, the surface roughness Ra of the metal thin film type back coat layer is 1 to 4 nm, the Rz is 10 to 50 nm, the friction coefficient is 0.4, and the running property is extremely poor. Treatment with an ion gun has been proposed for the purpose of improving the surface property, that is, for increasing the surface roughness.

However, the ion gun is expensive and has a problem in terms of processing capacity. The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic recording medium having improved conductivity and runnability, and further free from bad warpage that deteriorates recording and reproduction.

The object of the present invention is to provide a first surface on one side of the support.
Is a magnetic recording medium having a second metal thin film provided on the other surface thereof, wherein the second metal thin film is
Particles having a size of 100 nm are deposited, and the surface roughness Ra is 5 to 30 nm and Rz is 80 to 400 nm.
It is achieved by a magnetic recording medium characterized by

In this magnetic recording medium, in the second metal thin film, the reactive gas is made to collide with evaporated particles of metal or metalloid to coarsen the particles, and particles having a size of 5 to 100 nm are formed. It is preferably deposited. In particular, particles with a size of 7 to 20 nm are deposited and the surface roughness R
a is 5 to 30 nm (preferably about 10 to 30 nm), R
z is 80 to 400 nm (preferably about 100 to 200 n
It is more preferable that it is that of m).

A first metal magnetic film is provided on one surface of the support.
A method of manufacturing a magnetic recording medium having a second metal thin film provided on the other surface, wherein a reactive gas is caused to collide with evaporated particles of metal or metalloid to deposit particles having a size of 5 to 100 nm. The second metal thin film is constituted by the above method.

It is preferable that there are a plurality of reactive gas supply directions, all of which are directed toward the support, and these are in a direction intersecting with each other. Further, it is an apparatus for manufacturing a magnetic recording medium, which comprises a vacuum chamber, a container, and a non-magnetic support for evaporating a metal or metalloid metal material contained in the container and depositing the evaporated particles. So that the nozzle port for supplying the reactive gas to collide with the vaporized particles with the reactive gas faces the deposition surface of the support,
Further, it is achieved by an apparatus for manufacturing a magnetic recording medium, characterized in that a reactive gas supply means is provided so that the nozzle port is close to the container.

It is preferable that this manufacturing apparatus has a plurality of nozzle openings so that the directions of the reactive gas from the nozzle openings intersect. The present invention will be described below. The support of the magnetic recording medium used in the present invention is a non-magnetic one, and the support is polyester such as PET, polyamide, polyimide, polysulfone, polycarbonate, olefin resin such as polypropylene, cellulose resin, Polymer materials such as vinyl chloride resins and inorganic materials such as glass and ceramics are used.

A metal thin film type magnetic film is provided on one surface of the support by dry plating means such as vapor deposition means and sputtering means. Examples of the material of the magnetic particles forming the metal magnetic film include Co—Ni alloys, Co—Pt alloys, Co—Ni—P in addition to metals such as Fe, Co, and Ni.
t alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co
-Ni alloy, Fe-Co-B alloy, Co-Ni-Fe-
A B alloy, a Co-Cr alloy, or those containing a metal such as Al is used. Incidentally, it is preferable that an oxidizing gas or the like is supplied at the time of forming the metal magnetic film, and a protective layer made of an oxide film is formed on the surface layer of the metal magnetic film.

A so-called back coat layer (second metal thin film) is provided on the other surface side of the support. In the present invention, this back coat layer is a metal thin film formed by vapor deposition means. Examples of the material of the metal particles forming the back coat layer include Al, Zn, Sn, Ni, A
Metals such as g, Fe and Ti are used. Also, Cu-A
1-X (where X is one or more selected from the group consisting of Mn, Fe and Ni) based alloys, Al-Si based alloys, Ti alloys and the like are used. Incidentally, Cu-Al-X (where X is one selected from the group of Mn, Fe and Ni,
(Or two or more) -based alloy has a Cu content of 70-
90 at%, Al content is 8 to 25 at%, Mn content is 0.5 to 4 at%, Fe content is 0.4 to 5 at%.
And the Ni content is 0.4 to 4 at%, Mn, F
It is preferable that the total content of e and Ni is 1 to 6 at%. Further, the Al content in the Al-Si alloy is 15 to
It is preferable that the Si content is 70 at% and the Si content is 15 to 70 at%.

When the back coat layer is formed, the O element,
A reactive gas having a component such as N element or C element is supplied, and the metal thin film is partially transformed into an oxide, a nitride, or a carbide. Examples of such reactive gas include hydrocarbon gas such as oxygen, ammonia, methane, ethane, propane, ..., ethylene, ..., acetylene, etc., phosphine, silane, borane and the like.
Of these, oxygen is preferred.

That is, when the back coat layer is formed (during vapor deposition), the particles immediately after evaporation are irradiated (supplied) with a reactive gas such as oxygen and collided with the particles immediately after evaporation. Upon cooling, coalescence of particles occurs, coarsening of particles occurs, and particles having a size of 5 to 100 nm, particularly preferably particles having a size of 7 to 20 nm are deposited to form a back coat layer. Become. Therefore, the roughness of the back coat layer becomes appropriate, that is, the surface roughness R
a (center line average roughness) is 5 to 30 nm (preferably 10)
˜30 nm), Rz (10-point average roughness) is 80 to 400 n
m (preferably 100 to 200 nm), the friction coefficient is about 0.1 to 0.3, and the running property is excellent.

Here, when supplying a reactive gas such as oxygen, it is important to collide with particles immediately after evaporation. For example, even if the particles are made to collide with each other after vapor deposition on the support or immediately before vapor deposition, in this case, coalescence of particles cannot be expected, and it is not possible to achieve coarsening of the particles.
Ra of the backcoat layer is 5 to 30 nm and Rz is 8
It cannot be 0 to 400 nm.

That is, the reactive gas supply means may be provided so that the nozzle port for supplying the reactive gas faces the deposition surface of the support and the nozzle port is close to the evaporation source. It is preferable. Further, it was preferable that the direction of the reactive gas from the nozzle opening was set to intersect with each other because the roughness of the back coat layer could be increased. That is, when vapor deposition is performed as described above, it becomes as if a plurality of evaporation streams with different directions are formed, and when depositing on the surface of the support, irregularities are easily formed, and the roughness of the back coat layer is reduced. It can be made larger.

The supply amount of the reactive gas becomes too large,
When the backcoat layer is completely made into ceramic, the conductivity is lowered and vapor deposition becomes difficult, so that the supply amount of the reactive gas is limited. That is, as the supply amount of the reactive gas, the electric resistance value of the obtained back coat layer was 5 to 10 ⁵ Ω / sq. If it is such that the particles can be united with each other, or if vapor deposition is possible.

The relationship between the metal magnetic film provided on the surface of the support and the back coat layer is preferably such that the direction of stress exerted by the metal magnetic film and the direction of stress exerted by the back coat layer are the same. For example, when the stress generated by the metal magnetic film is of the tensile stress type, it is preferable to select the type (metal composition) and forming conditions of the backcoat layer so that the stress expressed by the backcoat layer is also of the tensile stress type. . When both films are of the tensile stress type, the absolute value of the stress produced by the back coat layer is designed to be larger than the stress produced by the metal magnetic film, whereby the curl rate is 0 to 15%. It is even more preferable to be 5 to 10%. When the stress generated by the metal magnetic film is of the compressive stress type, it is preferable to select the type (metal composition) and forming condition of the backcoat layer so that the stress expressed by the backcoat layer is also of the compressive stress type. . When both films are of the compressive stress type, the absolute value of the stress caused by the back coat layer is designed to be smaller than the stress caused by the metal magnetic film, whereby the curl rate is 0 to 15%. , Especially 5
More preferably, it is 10%.

The magnetic recording medium in which the back coat layer is formed by using such a metal material has (1) sufficient conductivity, antistatic property and dust adhesion are prevented. (2) The surface property is improved and running stability can be achieved. (3) Both sides of the support surface can be balanced and warpage can be prevented from occurring. That is the feature.

The back coat layer having such characteristics can be formed in the same manner as the metal magnetic film is formed.
Then, the formation of the back coat layer and the formation of the metal magnetic film may be performed simultaneously, the formation of the metal magnetic film may be performed after the formation of the back coat layer, or the back coating may be performed after the formation of the metal magnetic film. A layer may be formed. When performing the process separately, one thin film should be formed and wound on a roll, and then the roll should be taken out of the vacuum device into the atmosphere and loaded into another vacuum device to form the other thin film. However, there is no problem such as adhesion of dust.

The present invention will be described below with reference to specific examples.

[0026]

【Example】

[Embodiment 1] FIG. 1 is a schematic view of an apparatus for manufacturing a magnetic recording medium according to the present invention. In the figure, 1 is a vacuum container, 2 is a cooling can roll, 3a is a non-magnetic support (10 μm thick P
ET film) 4 supply side roll, 3b PET film 4 winding side roll, 5 MgO crucible, 6 electron gun, 7 shielding plate, 8a, 8b, 8c gas supply nozzles, PET A plurality of films 4 are arranged in parallel in the width direction of the film 4.

Then, using such a device, first,
For example, a Co—Ni alloy magnetic film is formed on the PET film 4. That is, the inside of the vacuum container 1 is 10 ⁻⁴ to 10 ⁻⁶ To.
After evacuation to a vacuum degree of about rr, electron beam heating of the electron gun 6 causes the magnetic metal (80% Co-
20% Ni) is evaporated, and a magnetic metal having a thickness of 0.04 to 1 μm, for example, 1800 Å is vapor-deposited on the PET film 4, whereby a metal thin film type magnetic recording medium is manufactured. The surface roughness R of the Co--Ni alloy magnetic film
a was 2 nm.

When forming this metal magnetic film, oxygen is supplied from the gas supply nozzle 8a to the vapor deposition portion to forcibly oxidize and oxidize the surface layer portion of the metal magnetic film to form a protective layer of an oxide film. The direction of the gas supply nozzle 8a is substantially parallel to the PET film 4 as shown in FIG.
Phase difference of 80 °).

After that, the take-up roll 3b is taken out and disposed on the support part of the supply-side roll so that the side on which the metal magnetic film is formed contacts the cooling can roll 2.
Then, the crucible 5 was filled with Al for constituting the back coat layer, the vacuum container 1 was evacuated to a vacuum degree of about 10 ⁻⁴ to 10 ⁻⁶ Torr, and then the crucible 5 was heated by an electron beam from the electron gun 6. The non-magnetic metal in the inside is evaporated, and 0.04 to 1 μm, for example, 3100Å on the other side of the PET film 4.
A non-magnetic metal Al is vapor-deposited.

When forming this Al film, air is supplied from the gas supply nozzles 8b and 8c (the supply amount is 120 sc).
cm). Therefore, oxygen molecules collide with the evaporated Al particles from the crucible 5 and the evaporated Al particles are cooled, whereby a coalescence phenomenon occurs, and the particles are larger than the particles immediately after evaporation. Moreover, since the gas supply nozzles 8b and 8c are oriented in the direction toward the PET film 4 and the gas supply nozzle 8b and the gas supply nozzle 8c are in the intersecting direction, a plurality of evaporative flows are generated. As it is formed, the surface roughness of the back coat layer (deposited Al film) becomes large. Furthermore, since the surface layer portion is oxidized, a protective layer made of an oxide film is formed, and the corrosion resistance is also improved.

After that, fluorine perfluoropolyether (grade: FOMBLIN ZDIAC carboxyl group modified, manufactured by Nippon Montedison Co., Ltd.) was added to a fluorine inert liquid (Fluorinert, FC-84, manufactured by Sumitomo 3M Co., Ltd.) so that the concentration of the perfluoropolyether became 0.1%. The diluted / dispersed paint is applied to the surface of the metal magnetic film by a die coating method so that the thickness after drying is about 20Å, dried at 90 ° C and slit into a predetermined width to obtain a magnetic tape. It was

[Embodiment 2] In Embodiment 1, Al used to form the back coat layer is Fe, and oxygen is supplied from the gas supply nozzles 8b and 8c (the supply amount is 100 sc).
cm) was similarly performed, and a magnetic tape was obtained. [Example 3] A magnetic tape was obtained in the same manner as in Example 1, except that Al used for forming the back coat layer was changed to Ti.

Example 4 In Example 1, Al used for forming the back coat layer was replaced with Cu-Al-Mn-
A Fe-Ni (80: 15: 2: 2: 1) alloy was used, and the same operation was performed except that the air supply amount was set to 200 sccm, to obtain a magnetic tape. [Example 5] A magnetic tape was obtained in the same manner as in Example 4, except that Al used for forming the back coat layer was changed to an Al-Si (65:35) alloy.

Comparative Example 1 A magnetic tape was obtained in the same manner as in Example 1, except that air was not supplied from the gas supply nozzles 8a, 8b, 8c when the back coat layer was formed. [Comparative Example 2] In Example 1, air was not supplied from the gas supply nozzles 8b and 8c when the back coat layer was formed, but the same operation was performed except that 120 sccm of air was supplied from the gas supply nozzle 8a. Got

[Characteristics] With respect to the magnetic tapes obtained in each of the above examples, the size of particles constituting the back coat layer, the surface roughness of the back coat layer, the friction coefficient, and the surface electric resistance were examined. Is shown in Table-1. Table-1 Particle size Surface roughness (nm) Friction coefficient Surface electric resistance (nm) Ra Rz (Ω / sq.) Example 1 7 7.4 84 0.27 2 × 10 ² Example 2 8 10. 5 95 0.21 5 × 10 ² Example 3 10 12.4 108 0.20 8 × 10 ² Example 4 15 25.2 173 0.18 6 × 10 ³ Example 5 16 26.7 215 0.16 4 × 10 ³ Comparative Example 1 1 1.5 18 0.41 1 or less Comparative Example 2 4 3.2 25 0.32 3 × 10 ² That is, when the backcoat layer is formed as described above, normal vacuum deposition is performed. The surface roughness was larger than that of the above, the friction coefficient was lowered, the running property was improved, and the recording / reproducing characteristics were improved.

Further, the antistatic effect was excellent, the adhesion of dust was prevented, the front and back surfaces were well balanced, and the contact with the magnetic head was good. By the way, compared to the conventional back coat layer with a coating type, the dropout is 3
It was about a few less. In addition, the dropout was reduced by about 20% compared to the case where the back coat layer was formed by a simple vacuum deposition method.

[0037]

According to the present invention, it is possible to obtain a magnetic recording medium which has a good running property, an excellent antistatic effect, a small dropout, an excellent reproducing characteristic, and a high recording capacity per volume.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a magnetic recording medium according to the present invention.

FIG. 2 is a schematic diagram of a magnetic recording medium.

[Explanation of symbols]

 1 Vacuum Container 2 Cooling Can Roll 3a Supply Side Roll 3b Winding Side Roll 4 PET Film 5 Crucible 6 Electron Gun 7 Shielding Plate 8a, 8b, 8c Gas Supply Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigemi Wakabayashi Inventor Shigemi Wakabayashi 2606 Akabane, Kaiga-cho, Haga-gun, Tochigi Kao Co., Ltd.Institute of Information Science (72) Inventor Akira Shiga 2606 Akabane, Kaiga-cho, Haga-gun, Tochigi Kao Company Information Science Laboratory

Claims (6)

[Claims] 1. A magnetic recording medium comprising a first metal magnetic film on one surface of a support and a second metal thin film on the other surface, wherein the second metal thin film has a thickness of 5 to 100 nm. Particles of a large size are deposited, and the surface roughness Ra is 5 to 30 nm and Rz is 80 to 400.
A magnetic recording medium having a thickness of nm. 2. The second metal thin film is formed by depositing particles having a size of 5 to 100 nm by causing a reactive gas to collide with evaporated particles of a metal or a semimetal to coarsen the particles. The magnetic recording medium according to claim 1, wherein: 3. A method for manufacturing a magnetic recording medium, comprising a first metal magnetic film on one surface of a support and a second metal thin film on the other surface, the method comprising reacting with evaporated particles of metal or metalloid. A method for manufacturing a magnetic recording medium, characterized in that the second metal thin film is formed by causing a reactive gas to collide to deposit particles having a size of 5 to 100 nm. 4. The production of a magnetic recording medium according to claim 3, wherein there are a plurality of reactive gas supply directions, all of which are directed toward the support, and these are in a direction intersecting with each other. Method. 5. A magnetic recording medium comprising: a vacuum chamber; a container; and a non-magnetic support for evaporating a metal or metalloid metal-based material contained in the container and depositing the evaporated particles. The device is such that a nozzle port for supplying a reactive gas for colliding the reactive gas with the vaporized particles faces the deposition surface of the support, and the nozzle port is close to the container. An apparatus for manufacturing a magnetic recording medium, characterized in that reactive gas supply means is provided. 6. The apparatus for manufacturing a magnetic recording medium according to claim 5, wherein a plurality of nozzle openings are provided so that the directions of the reactive gas from the nozzle openings intersect each other.