JPH04168626A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To strengthen adherence of a carbon layer to a magnetic layer and to improve durability by emitting ions and electrons from an ion gun to the surface of the magnetic layer immediately before the carbon layer is formed. CONSTITUTION:A polymer film 1 formed with a magnetic layer is fed along the periphery of a cylindrical can 2 in a direction of an arrow A. Ions and electrons 4 from an ion gun 3 are first emitted to the surface of the layer on the film 1 with the layer, and subsequently a carbon layer is formed by an evaporation source 5. In this case, the can 2 can be heated, and the temperature of the film 1 with the layer during depositing can be controlled. Thus, the adhesive properties of the carbon layer to the magnetic layer become rigid, and durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the production of thin-film magnetic recording media with excellent durability and runnability, in which a carbon layer is formed on the surface of a thin-film magnetic layer after treatment. Regarding the method.

Conventional technology Conventionally, coated magnetic recording media have been used, in which magnetic powder is coated on a non-magnetic substrate such as a polymer film, but in order to achieve higher recording density, a non-magnetic substrate Thin film types, on which a thin metal film is formed by sputtering or vacuum evaporation, are being put into practical use. Among thin film magnetic recording media, magnetic recording media in which a CO-based magnetic thin film is formed as a magnetic layer are attracting attention because of their excellent short wavelength recording characteristics.

Thin-film magnetic recording media with excellent recording and reproducing characteristics,
Durability is an issue when forming layers. A protective layer is provided on the surface of the magnetic layer as a means to improve durability. A carbon layer is one of these protective layers. The carbon layer is made by vapor deposition.

It is formed by a sputtering method, a plasma CVD method, or the like. The formed carbon layer takes the form of graphite, amorphous, diamond, or a mixture of these depending on the manufacturing method and conditions. From an industrial standpoint, vapor deposition is suitable for mass production. In general, the carbon layer formed by the condensation method is a mixture of graphite and amorphous carbon. Such a carbon layer imparts excellent lubricity and durability to the magnetic recording medium.

Problems to be Solved by the Invention As mentioned above, carbon layers obtained by various methods have excellent characteristics depending on the manufacturing method, but a common problem is that the adhesion between the carbon layer and the magnetic layer is poor and peeling occurs. It's easy. If peeled off, the magnetic head may be damaged or recording/reproduction becomes unstable, which is a serious problem. Therefore, it is strongly desired to firmly laminate a carbon layer having excellent properties on the surface of a magnetic layer, and the present invention satisfies this demand.

Means for Solving the Problems The present invention realizes the above-mentioned needs, and when a carbon layer is formed in vacuum on the surface of one armpit type magnetic layer formed on a polymer film, the polymer film is This method is characterized in that the surface of the magnetic layer is irradiated with ions and electrons from an ion gun while the film is run along the circumferential surface of a cylindrical can to subsequently form the carbon layer.

Function: The present invention cleans and activates the surface of the magnetic layer by irradiating the surface of the magnetic layer with ions and electrons from an ion gun immediately before forming the carbon layer, thereby improving the adhesion between the carbon layer and the magnetic layer. becomes stronger and improves durability.

Example Examples will be described below.

First, the structure of a magnetic recording medium manufactured by the method of the present invention will be explained. FIG. 2 is a diagram schematically showing a cross-sectional structure of a magnetic recording medium. A magnetic layer 21 made of magnetic material is disposed on a polymer film 20, and a carbon layer 22 is formed thereon.

Furthermore, if necessary, a lubricant may be applied on the carbon layer 22 and a bank coat layer may be applied on the back surface of the polymer film 20. The polymer film 20 is made of polymer materials such as polyethylene terephthalate, polyethylene naphthalate, aromatic polyamide, and polyimide, which are generally used as substrates for magnetic recording media.

The magnetic layer 21 is made of metal dioxide or a mixture thereof, and is a single layer film or a multilayer film laminated in multiple layers. Furthermore, the magnetic layer 21 made of a magnetic thin film may have a plurality of underlayers, intermediate layers, and overlayers made of magnetic or nonmagnetic materials.

The carbon layer 22 has the magnetic layer 21 within a range having desired characteristics.
The thinner the film, the better.

Next, a method for forming the carbon layer will be explained.

FIG. 1 is a diagram schematically showing the internal structure of a vacuum bonding apparatus used in a method of manufacturing a magnetic recording medium in an embodiment of the present invention. A polymer film on which a magnetic layer is formed (hereinafter referred to as a polymer film with magnetic layer) 1 is a cylindrical can 2
Ions and electrons 4 from the ion gun 3 are irradiated onto the surface of the magnetic layer on the polymer film 1 with a magnetic layer. Subsequently, a carbon layer is formed by the evaporation source 5. 6 and 7 are a supply roll and a take-up roll for the magnetic layer-coated polymer film 1, respectively.

The temperature of the cylindrical can 2 can be increased, and the temperature of the magnetic layer-coated polymer film 1 during adhesion can be controlled.

As the evaporation source 5, a resistance heating evaporation source, an electron beam evaporation source, or the like, which heats and evaporates carbon rod by passing a large current through it, can be used.

An electron beam evaporation source is suitable for depositing carbon over a large area at high speed.

The ion gun 3 is similar to those commonly used in ion beam sputtering, ion milling, substrate pretreatment, and the like. The outline of the ion gun 3 is shown in FIG.
Accelerated ions 32 such as 2 and N2.02 come out. Generally, A is used. 31 is a neutralizer, and by passing a current through it, electrons 3
3 occurs.

4 in FIG. 1 is a mixture of ions 32 and electrons 33.

Specific examples will be described below.

Using the vacuum shrinkage apparatus shown in FIG. 1, a carbon layer was formed on the surface of a Co--Cr magnetic thin film as a magnetic layer with a thickness of 0.2 μm formed on a polyimide film with a film thickness of 8 μm. Note that the Co--Cr film is attracting attention as a high-density magnetic recording medium. As the evaporation source 5, an electron beam evaporation source was used.

Further, the surface of the polymer film is smooth and has not been subjected to any special surface treatment to create irregularities.

(Conventional Example) First, film formation was performed using a conventional method. That is, without operating the ion gun 3, the polyimide film was run at a speed of 10 m/min in the direction of arrow A to obtain a film thickness of 0.01 to 0.
．． A carbon layer of 0.05 μm was formed. Note that the temperature of the cylindrical can was room temperature.

(Example 1) Next, one method of the present invention was implemented to form a film. At this time, a Kaufmann type ion gun 3 is used, the acceleration voltage of the ion gun is -500μ, the ion current density is O,
1 mA/cd, the gas introduced into the ion gun was Ar(ilji
The amount of L was 10 cc/min), and a current was passed through the neutralizer 31 to generate electrons. The electron current density was set to 0.1 mA/cd, which is almost the same as the ion current density. The polyimide film was run in the direction of arrow A at a speed of 10 m/min to form a carbon layer with a thickness of 0.01 to 0.05 μm. Note that the temperature of the cylindrical can was room temperature.

(Example 2) Ar introduced into the ion gun under almost the same conditions as Example 1.
The experiment was carried out by adding CH4 gas to the gas.

Note that the composition ratio and amount of gas introduced are Ar:CH,-3
: 2 and 10 cc/min (total flow rate).

(Example 3) Under substantially the same conditions as in Example 1, the temperature of the cylindrical can was varied from room temperature to 300°C. Note that the thickness of the carbon layer was kept constant at 0.1 μm.

For the media obtained in the above 1 conventional example and 3 examples, the dynamic friction coefficient μ was evaluated by the drawing test method,
In addition, as a durability evaluation, still durability time was measured. The coefficient of dynamic friction μ8 is approximately 0.2 with almost no difference between samples.
It showed low values before and after.

The still durability times are summarized in Tables 1 and 2. Here, the still durability time is defined as the elapsed time when the reproduction output decreases by 3 dB from the initial reproduction output. A modified commercially available 8 mm VTR was used for the measurements. Note that the measurements were conducted without applying any lubricant or back coat layer. The results are shown in Tables 1 and 2 below.

(Margin below) As is clear from Table 1, Table 2, and Table 1, it can be seen that the durability is improved by implementing the present invention. It is significant that this improvement effect is more pronounced when the carbon layer is thinner than when it is thicker. The thinner the carbon layer is, the more desirable it is from the viewpoint of recording and reproducing characteristics, and excellent C/N characteristics can be achieved.

As is clear from Table 2, it can be seen that when the temperature of the cylindrical can when forming the carbon layer is 150° C. or higher, the durability is significantly improved.

As described above, the reason why the durability was significantly improved by implementing the present invention is not clear, but it is thought that it is due to the improvement in the adhesion between the carbon layer and the magnetic layer and the effect of modifying the carbon layer. The improvement in adhesion is thought to be due to cleaning and activation of the magnetic layer surface by ion irradiation. Electrons are also irradiated with ions in order to prevent trTH caused by ions to the film and various parts within the vacuum chamber. One of the effects of modifying the carbon layer is that by ionizing and irradiating carbon-containing gas, active carbon particles are firmly adsorbed to the surface of the magnetic layer and act as nuclei when forming the carbon layer. .

Another factor is the temperature of the cylindrical can during the formation of the carbon layer; at temperatures above I50'C, the carbon particles that have reached the magnetic layer become more mobile, resulting in the formation of a dense carbon layer. It will be done.

When forming a carbon layer at high temperatures, it is necessary to select a polymer film with sufficiently high heat resistance.

In the above examples, only the case where Co-CrM was formed as a magnetic layer on a polyimide film with a smooth surface was explained, but it is clear that the present invention is also effective for other polymeric materials or magnetic layers. . In addition, if fine protrusions or irregularities are provided on the surface of the polymer film that forms the magnetic layer, the durability will be further improved, according to fifi.
It has been certified.

In the examples, a vacuum evaporation method was used to form the carbon layer, but similar effects can be obtained by sputtering, plasma CVD, thermal decomposition, and the like.

Effects of the Invention As is clear from the above examples, according to the present invention, a carbon layer with excellent durability can be obtained even if the film thickness is thin.
A high-performance thin-film magnetic recording medium suitable for high-density recording can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically showing the internal structure of a vacuum evaporation apparatus used in a method for manufacturing a magnetic recording medium in an embodiment of the present invention;
FIG. 2 is a diagram schematically showing a cross section of a thin film magnetic recording medium manufactured in an embodiment of the present invention, and FIG. 3 is a diagram schematically showing an ion gun. 1... Polymer film on which a magnetic layer is formed, 2
......Cylindrical can, 3...Ion gun,
4...Ions and electrons, 5...1 source, 20...Polymer film, 21...
Magnetic layer, 22... Carbon layer. Name of agent: Patent attorney Yasuaki Kobe Haga 2 names Tsuru i Zurei 2 Kuku 3

Claims (3)

[Claims] (1) When forming a carbon layer in vacuum on the surface of a thin magnetic layer formed on a polymer film, the magnetic layer is A method of manufacturing a magnetic recording medium, comprising irradiating the surface of the magnetic recording medium with ions and electrons from an ion gun, and subsequently forming the carbon layer. (2) The method for manufacturing a magnetic recording medium according to claim 1, characterized in that the temperature of the cylindrical can is raised to 150° C. or higher. (3) The method for manufacturing a magnetic recording medium according to claim 1, characterized in that carbon-containing gas is ionized and irradiated with ions and electrons.