JPH10255263A - Magnetic recording media - Google Patents

Abstract

(57) [Problem] To provide a vapor-deposited magnetic recording medium on which a protective film having excellent running properties and durability is formed. SOLUTION: When a carbon film is formed on a vapor-deposited magnetic recording medium by a CVD method, ethylene is used as a raw material,
By adding r gas, the practical characteristics are improved. The carbon protective film has an ethylene / Ar ratio of 2/1 to 1 /.
The film is formed in a molar ratio range of 6/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium in which a magnetic layer made of a metal magnetic thin film is formed on a non-magnetic support.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as an oxide magnetic powder or an alloy magnetic powder has been coated on a non-magnetic support by a vinyl chloride / vinyl acetate copolymer, a polyester resin, a urethane resin, or the like. 2. Description of the Related Art A coating type magnetic recording medium produced by applying and drying a magnetic coating material dispersed in an organic binder such as a polyurethane resin is widely used.

On the other hand, with the growing demand for high-density magnetic recording, Co-Ni alloys, Co-Cr alloys,
A metal magnetic material such as -O is directly non-deposited on a non-magnetic support such as a polyester film, a polyamide or a polyimide film by plating or vacuum thin film forming means (vacuum vapor deposition method, sputtering method, ion plating method, etc.),
A so-called metal magnetic thin film type magnetic recording medium has been proposed and attracts attention.

The magnetic recording medium of the metal magnetic thin film type is excellent in coercive force, squareness ratio, etc., and the thickness of the magnetic layer can be made extremely thin. In addition to excellent properties, the magnetic layer has a number of advantages such as a higher packing density of the magnetic material because there is no need to mix the binder, which is a non-magnetic material, into the magnetic layer. That is, the metal thin film medium is considered to be the mainstream of high density magnetic recording media because of its excellent magnetic properties.

Further, in order to improve the electromagnetic conversion characteristics of this type of magnetic recording medium and to obtain a larger output, when forming the magnetic layer of the magnetic recording medium, the magnetic layer must be inclined. The so-called oblique deposition for vapor deposition has been proposed and put to practical use.

[0006] In the future, magnetic recording media tend to be smoothed in order to reduce spacing loss from the trend of higher density. The frictional force between the head and the medium accompanying the smoothing of the magnetic recording medium increases, and the shear force generated on the medium increases. In such a situation where the sliding durability becomes severe, a technique of forming a protective film layer on the surface of the magnetic layer has been studied for the purpose of improving the durability.

As such a protective film, a carbon film, a quartz (SiO ₂ ) film, a zirconia (ZrO ₂ ) film and the like have been studied, and some hard disks have been put to practical use and produced. Particularly recently, a diamond-like carbon (DLC), which is a harder film, has been used as a carbon film.
The formation of a film such as a film has been studied, and it is a protective film that is expected to become mainstream in the future. As a method for forming the DLC film, a sputtering method and a CVD method are used.

[0008]

According to the sputtering method for forming a DLC film, first, a target atom is repelled by the kinetic energy of an inert gas such as an Ar gas using an electric or magnetic field. Then, the ejected atoms are deposited on the opposing substrate to form a target film. DLC by this process
The film formation speed is generally slow, and this is a film formation means having low productivity from an industrial point of view. On the other hand, the CVD method is a chemical process for forming a film by causing a chemical reaction such as decomposition and synthesis of a raw material gas by using energy of plasma generated by using an electric or magnetic field.

[0009] The carbon film formed by these methods is required to have stricter durability in the future, and further improvement is desired. An object of the present invention is to provide a vapor-deposited magnetic recording medium on which a protective film having excellent running properties and durability is formed.

[0010]

DISCLOSURE OF THE INVENTION The present invention is embodied in order to solve the above-mentioned problems, and ethylene is used as a raw material when forming a carbon film on a vapor-deposited magnetic recording medium by a CVD method. By using and further adding Ar gas, practical characteristics are improved. That is, the present invention is a magnetic recording medium in which a carbon protective film raw material is formed from ethylene and Ar gas in a deposited magnetic recording medium with a carbon protective film.

It is desirable that the protective film of the above-mentioned deposited magnetic recording medium of the present invention is formed by a CVD method. Further, the carbon protective film is formed in a range of a molar ratio of ethylene / Ar of 2/1 to 6/1. If the molar ratio of ethylene / Ar is less than 2/1, good characteristics cannot be obtained, and if it exceeds 6/1, the effect of adding Ar is lost and good characteristics cannot be obtained. There is a defect.

In the present invention, all magnetic media (disks, tapes, etc.) in which a magnetic recording layer is provided on a non-magnetic support and a carbon protective layer is further provided thereon are intended. On the other hand, the effect is great in a tape medium that requires severe environmental resistance.

On the non-magnetic support, a ferromagnetic metal material is directly applied to form a metal magnetic thin film as a magnetic layer, and this metal magnetic material is used for a general vapor deposition tape. Any object can be used. For example, ferromagnetic metals such as Fe, Co and Ni, Fe-Co, Co-Ni, Fe-Co-Ni,
Fe-Cu, Co-Cu, Co-Au, Co-Pt, M
n-Bi, Mn-Al, Fe-Cu, Co-Cu, Co
-Au, Co-Pt, Mn-Bi, Mn-Al, Fe-
Cr, Co-Cr, Ni-Cr, Fe-Co-Cr, C
Ferromagnetic alloys such as o-Ni-Cr and Fe-Co-Ni-Cr are exemplified. These may be a single layer film or a multilayer film. Furthermore, it may be between the nonmagnetic support and the metal magnetic thin film, or in the case of a multilayer film, between each layer. Furthermore, an underlayer or an intermediate layer may be provided between the nonmagnetic support and the metal magnetic thin film, or in the case of a multilayer film, for improving the adhesion between the layers and controlling the coercive force.

Means for forming a metal magnetic thin film include a vacuum evaporation method in which a ferromagnetic material is heated and evaporated under vacuum and deposited on a nonmagnetic support, and an ion plating method in which a ferromagnetic metal material is evaporated during discharge. A PVD technique such as a sputtering method or a sputtering method in which glow discharge is caused in an atmosphere containing argon as a main component to strike out atoms on the target surface with argon ions generated.

The magnetic tape according to the present invention is not limited to the above constitution, but may be modified without departing from the scope of the present invention, for example, forming a back coat layer as necessary, or using a non-magnetic support. There is no problem in forming an undercoat layer or a layer of a lubricant or the like thereon. In this case, any conventionally known materials can be used as the material contained in the non-magnetic pigment, resin binder or lubricant contained in the back coat layer.

[0016]

Embodiments of the present invention will be described below. Examples of the present invention and comparative examples will be described based on experimental results. The conditions for producing the deposition medium of the example and the comparative example are common and are as follows. Base: polyethylene teftate (10 μm thick, 150
Undercoat: Applying a water-soluble latex containing acrylic ester as a main component Density: 10 million pieces / mm ² Vapor deposition conditions Ingot: Co, Co80-Ni-20 wt% Incident angle: 45 to 90 degrees Tape speed: 0.17 m / sec. Magnetic layer thickness: 0.2 μm Oxygen introduction amount: 3.3 × 10 ^{−6 to} 4.0 × 10 ⁻⁶ m ³ / s
ec. Vacuum degree during vapor deposition: 7 × 10 ^-4 Pa Back coat: A mixture of carbon and urethane binder applied at a thickness of 0.6 μm

On the metal magnetic thin film formed by the above method,
A diamond-like carbon film was formed to a thickness of 10 nm by a CVD method. The film forming method will be described below. EXAMPLES Hereinafter, specific examples of the present invention will be described. First, a method for manufacturing a magnetic recording medium according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a main part configuration diagram of a plasma CVD continuous film forming apparatus used for forming a DLC film of the present embodiment.

A vacuum chamber 1 provided with a vacuum exhaust system 10
In FIG. 1, a workpiece 1 in which a partially oxidized ferromagnetic metal thin film is formed by depositing Co while introducing oxygen gas onto a PET film as a nonmagnetic support is fed from an unwinding roll 3 to a rotating support 2 and a drum. The paper is passed along the opposing electrode 9 and wound up on the winding roll 4. An electrode 6 is incorporated inside the reaction tube 5. Further, a potential of +500 V to 2000 V is applied to the electrode 6 by the DC power supply 7.
A gas containing a hydrocarbon as a main component is introduced into a discharge gas inlet 8 of the reaction tube 5. The reaction tube 5 is provided with a cylindrical rotatable counter electrode 9.

The object 1 is wound around the surface of the counter electrode 9, and a carbon film is formed on the surface of the object 1 inside the reaction tube 5 until a carbon film has a predetermined thickness. On the other hand, the plasma surface treatment chamber 12 has an electrode 13 and a gas inlet 14, a gas containing fluorine is introduced from the gas inlet 14, and a voltage is applied to the gas to convert the gas into a plasma state into the gas 1. The surface is treated by touching the carbon film. The conditions for forming the carbon film are described below. Introduced gas: ethylene + argon (Ar) Reaction pressure: 10 Pa DC power: DC 1.5 kV

Under these film forming conditions, the ethylene gas flow rate was kept constant, the ethylene / Ar ratio was 1: 1 (Comparative Example 1),
Films were formed at a ratio of 2: 1 (Example 1), 3: 1 (Example 2), 4: 1 (Example 3), and 6: 1 (Example 4). It is shown in FIG.

[Table 1]

The method of evaluating each practical characteristic is as follows. 1) Measurement of friction coefficient The friction coefficient was controlled by controlling 80% of 40 ° C in a constant temperature and high humidity bath.
I ran the 00 pass. The friction coefficients shown in Table 1 are values for the first and 100th shuttle runs. 2) Shuttle measurement In the shuttle measurement, in a normal temperature environment, after running 100 passes, the playback output was measured to what dB the initial output decreased. 3) Still measurement Still measurement was performed in a constant temperature bath at -5 ° C.
The time until the dB dropped was measured.

As can be seen from Table 1, Examples 1, 2, 3, and 4 of the Examples show characteristics superior in running property and durability as compared with Comparative Examples. Ethylene / Ar is 2/1 to 6/1
Excellent characteristics are obtained in the range of

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of a plasma CVD continuous film forming apparatus used for forming a DLC film according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Object to be processed 2 Rotary support body 3 Unwinding roll 4 Take-up roll 5 Reaction tube 6 Electrode 7 DC power supply 8 Discharge gas inlet 9 Counter electrode 10 Vacuum exhaust system 11 Vacuum chamber 12 Plasma surface treatment chamber 13 Electrode 14 Gas inlet

Claims (3)

[Claims] 1. A magnetic recording medium in which a carbon protective film material is formed from ethylene and Ar gas in a vapor deposited magnetic recording medium with a carbon protective film. 2. The magnetic recording medium according to claim 1, wherein the protective film of the deposited magnetic recording medium is formed by a CVD method. 3. The carbon protective film has an ethylene / Ar ratio of 2 /
3. The magnetic recording medium according to claim 2, wherein the film is formed in a molar ratio of 1 to 6/1.