JPH0855335A - Method of manufacturing magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve electrical conductivity and running performance by depositing metal particles by vacuum deposition in a specified vacuum atmosphere on the back surface of a magnetic recording medium raw sheet on which a metal thin film magnetic film is formed. CONSTITUTION:A metal thin film-type back coating film of 0.04-1mum thickness is formed on the back surface of a magnetic recording medium raw sheet 3 by vapor deposition in a vapor deposition device. The device consists of a vacuum chamber 7 which houses a cooling can roll 1, supply/winding rolls 2a, 2b, crucible 5 and the like. The back coating film is, for example, a Cu-Al-X alloy containing 70-90 at% Cu and 8-20at% Al and X is one or more elements selected from Mn, Fe and Ni. The film is formed by keeping the atmosphere of the vacuum chamber 7 to 5X10 to 9X10<-2>Torr vacuum degree with >50% partial pressure of water and 5m/min travelling rate of the raw sheet 3. By this method, the surface roughness of the back coating film is made rather large, and the obtd, medium has a small coefft. of friction of 0.2 to 0.3 during running and has excellent running performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium.

[0002]

BACKGROUND OF THE INVENTION In a magnetic recording medium such as a magnetic tape, due to a demand for high density recording, a binder resin is not used as a magnetic layer provided on a non-magnetic support, instead of a coating type using a binder resin. A metal thin film type that is not used has been proposed. That is, it is well known that a magnetic recording medium having a magnetic layer formed by a dry plating means such as vacuum deposition, sputtering or ion plating has been proposed. Since the magnetic recording medium of this type has a high packing density of magnetic material, it is suitable for high-density recording.

By the way, the metal thin film type 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, 32
Has a thickness of, for example, 150 using a vacuum deposition method.
0ÅCo-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 the magnetic layer becomes dirty or dust adheres in the step of applying the back coat layer, and dropout increases.
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 deposition method is (1)
By having conductivity, it is possible to prevent static electricity and prevent dust from adhering. (3) The front magnetic layer and the back magnetic layer are balanced to prevent warpage. Although it can exhibit the features of (2), it improves the surface property (friction coefficient),
Get driving stability. 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 film is 1 to 4 nm, the Rz is 10 to 50 nm, the friction coefficient is 0.5, and the running property is extremely poor. The present invention has been made in view of the above points, and a first 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. Is.

A second object of the present invention is to provide a magnetic recording medium which has an appropriate surface roughness after film formation and which is excellent in running property, even if the surface roughening work with a polishing tape is not carried out. It is to provide a technology that can be obtained at a cost. An object of the present invention is a method for producing a magnetic recording medium in which flying metal particles are attached / deposited on a support to provide a metal thin film, and the adhesion / deposition of the metal particles is from 5 × 10 ^-2 to 9x
This is achieved by a method for manufacturing a magnetic recording medium, which is performed in a vacuum atmosphere of 10 ^-2 Torr.

Particularly, when the partial pressure of water is 50% or more, 5 × 10 5
^-2~ 9 × 10^-2Attaching metal particles under a vacuum atmosphere of Torr
Achieved by a magnetic recording medium manufacturing method that deposits and deposits
Be done. In addition, such a manufacturing method is performed by using the vapor deposition apparatus as shown in FIG.
It can be performed using a table. That is, in the device of FIG.
The atmosphere in the vacuum chamber 7 is set to 5 × 10.^-2~ 9 × 10 ^-2
Torr, especially 5 × 10 when the partial pressure of water is 50% or more^-2~
9 x 10^-2All you have to do is set the vacuum atmosphere in Torr.
Yes. Therefore, the vacuum atmosphere is set to 5 × 10.^-2~ 9 × 10 ^-2To
rr, especially when the partial pressure of water is 50% or more, 5 × 10^-2~ 9x
10^-2It only needs to be controlled by Torr, and conventional equipment can be used.
It can be used as it is and can be implemented at an extremely low cost. So
The surface roughness of the metal film thus obtained is moderate.
It has a rough surface. That is, under the above conditions
When deposited on a support, the average of the metal particles flying in
The free path is short and the growing metal particles are relatively large.
And large metal particles will adhere and accumulate.
Therefore, it is considered that the surface roughness will be increased.
Therefore, the friction coefficient during running is about 0.2 to 0.3
Therefore, the running property is excellent. Therefore, in durability
A magnetic recording medium that is rich and has excellent recording and playback characteristics
can get.

As the support for the magnetic recording medium used in the present invention, for example, polyester such as PET, polyamide, polyimide, polysulfone, polycarbonate,
An olefin resin such as polypropylene, a cellulose resin, a polymer material such as a vinyl chloride resin, or an inorganic material such as glass or ceramic is used. A metal such as Al, Zn, Sn, Ni, Ag, Fe or Ti is used for the metal thin film (so-called back coat film) provided on the support. Also, Cu-Al-X (where X is M
One or more selected from the group consisting of n, Fe and Ni) based alloys, Al-Si based alloys, Ti alloys and the like are used. Cu-Al-X (where X is Mn, Fe,
One or two or more selected from the group of Ni) -based alloy has a Cu content of 70 to 90 at%, an Al content of 8 to 25 at%, and a Mn content of 0.5 to 4 at%.
It is preferable that the Fe content is 0.4 to 5 at%, the Ni content is 0.4 to 4 at%, and the total content of Mn, Fe, and Ni is 1 to 6 at%. Also, Al-Si
The Al content in the system alloy is preferably 15 to 70 at%, and the Si content is preferably 15 to 70 at%.

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

[0013]

【Example】

Example 1 The vapor deposition device shown in FIG. 1 is used.
In FIG. 1, 1 is a cooling can roll, 2a is a supply side roll, 2b is a take-up side roll, 3 is a magnetic recording medium roll, 4
Is a shielding plate, 5 is a crucible, 6 is a metal (Cu-Al alloy), 7 is a vacuum chamber, and 8 is an oxidizing gas supply nozzle.

In the apparatus of FIG. 1, the inside of the vacuum chamber 7 is
Once evacuated to a vacuum degree of about 1 × 10 ^-6 Torr,
The exhaust of the cryopump is stopped, and the exhaust system of the rotary pump and the mechanical booster pump is used to generate 6 × 10.
A vacuum atmosphere of ^-2 Torr (partial pressure of water: 50%) was used. Then, the metal (Cu-Al alloy) 6 in the crucible 5 is melted and vaporized by the heating means of the induction heating system, and is run (speed 5 m / min) by being attached to the cooling can roll 1 from the supply side roll 2a. Roll of magnetic recording medium (PET
0.04 to 1 μm, for example 0.2 μm, with respect to the back surface (the surface on which the metal thin film type magnetic film is not formed) of the support 3 such as a film on which the metal thin film type magnetic film is formed)
After being vapor-deposited in a thickness of m, the film was wound on a winding roll 2b to manufacture a metal thin film type magnetic recording medium.

[Embodiment 2] The back coat in Embodiment 1
Film forming conditions (6 × 10 with 50% water partial pressure) ^-2To
vacuum atmosphere of rr), with a partial pressure of water of 55%, 7 × 10
^-2The same procedure was performed except that the vacuum atmosphere was Torr. [Embodiment 3] A film for forming a back coat film in Embodiment 1
Case (partial pressure of water is 50%, 6 × 10 ^-2Torr vacuum atmosphere
Atmosphere), the partial pressure of water is 55%, 8 × 10^-2Torr
The same operation was performed except that a vacuum atmosphere was used.

[Embodiment 4] The back coating in Embodiment 1
Film forming conditions (6 × 10 with 50% water partial pressure) ^-2To
(vacuum atmosphere of rr), with a partial pressure of water of 75%, 5 × 10
^-2The same procedure was performed except that the vacuum atmosphere was Torr. [Embodiment 5] A film for forming a back coat film in Embodiment 1.
Case (partial pressure of water is 50%, 6 × 10 ^-2Torr vacuum atmosphere
Atmosphere), the partial pressure of water is 85%, 5 × 10^-2Torr
The same operation was performed except that a vacuum atmosphere was used.

[Sixth Embodiment] The back coating in the first embodiment.
Film forming conditions (6 × 10 with 50% water partial pressure) ^-2To
(vacuum atmosphere of rr), with a partial pressure of water of 95%, 5 × 10
^-2The same procedure was performed except that the vacuum atmosphere was Torr. [Embodiment 7] A film for forming a back coat film in Embodiment 1.
Case (partial pressure of water is 50%, 6 × 10 ^-2Torr vacuum atmosphere
Atmosphere), the partial pressure of water is 95%, 9 × 10^-2Torr
The same operation was performed except that a vacuum atmosphere was used.

[Comparative Example 1] The back coat in Example 1
Film forming conditions (6 × 10 with 50% water partial pressure) ^-2To
(vacuum atmosphere of rr), with a partial pressure of water of 80%, 5 × 10
^-FiveThe same procedure was performed except that the vacuum atmosphere was Torr. [Comparative Example 2] A film for forming a back coat film in Example 1
Case (partial pressure of water is 50%, 6 × 10 ^-2Torr vacuum atmosphere
Atmosphere), the partial pressure of water is 40%, 2 × 10^-3Torr
The same operation was performed except that a vacuum atmosphere was used.

[Characteristics] The friction coefficient of the magnetic tape obtained in each of the above examples was examined, and the results are shown in Table 1. According to this, by setting the vacuum atmosphere at the time of film formation as in the present invention, the surface roughness of the film formed becomes relatively large, and as a result, the friction coefficient during running is 0. 2 to 0.3, the running characteristics are good and the recording / reproducing characteristics are excellent.

On the other hand, under the conditions of Comparative Example 1 and Comparative Example 2, the surface roughness of the formed film was small, and as a result, the friction coefficient during running was 0.4 or more, and the sticking Etc., the running characteristics are poor, the durability is low, and the recording / reproducing characteristics are also inferior.

[0021]

[Effect] It is possible to obtain a high-performance magnetic recording medium which is excellent in running property and rich in durability at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a magnetic recording medium.

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

[Explanation of symbols]

 1 Cooling Can Roll 2a Supply Side Roll 2b Winding Side Roll 3 Raw Material of Magnetic Recording Medium 5 Crucible 6 Metal 7 Vacuum Tank

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

Claims (2)

[Claims] 1. A method of manufacturing a magnetic recording medium in which a metal thin film is provided by depositing and depositing flying metal particles on a support, wherein the depositing and depositing of the metal particles is 5 × 10 5.
^A method for manufacturing a magnetic recording medium, which is performed in a vacuum atmosphere of ^{−2 to} 9 × 10 ⁻² Torr. 2. The partial pressure of water is 50 for adhesion and deposition of metal particles.
% Or more, 5 × 10 ^-2~ 9 × 10^-2Torr vacuum atmosphere
The magnetic recording medium according to claim 1, wherein
Production method.