Coating processes – Direct application of electrical – magnetic – wave – or... – Plasma
Reexamination Certificate
1999-12-22
2002-01-22
Pianalto, Bernard (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Plasma
C427S131000, C427S249100, C427S249700, C427S250000, C427S255280, C427S255390, C427S255700, C427S294000, C427S404000
Reexamination Certificate
active
06340505
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a magnetic recording medium used in, for example, a magnetic disk apparatus, and to a production process for the medium.
BACKGROUND OF THE INVENTION
A conventionally used magnetic recording medium comprises a non-magnetic substrate on which a non-magnetic undercoat film and a magnetic film are formed, a protective film formed through sputtering on the magnetic film by use of a material such as carbon, and a lubrication film having a thickness of tens of Å, which is formed on the protective film by the application of a lubricant such as perfluoropolyether.
Recently, a magnetic recording medium of high recording density has been demanded, and a magnetic recording medium capable of reducing spacing loss has also been demanded.
However, when the thickness of a protective film and a lubrication film are reduced in order to decrease spacing loss, sliding durability may deteriorate. Therefore, at the present time, a magnetic recording medium having high sliding durability, wherein recording density can be sufficiently increased, is not attained.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention provides a magnetic recording medium having excellent durability and capable of increased recording density, and a production process for the medium.
The production process for a magnetic recording medium according to the present invention comprises forming a hydrogenated carbon protective film on a disk through a plasma CVD method making use of a reaction gas containing a hydrocarbon serving as a raw material, which disk comprises a non-magnetic substrate on which a non-magnetic undercoat film and a magnetic film are formed, and the protective film has a density of 2.2 g/cm
3
or more.
When the hydrogenated carbon protective film is formed, pulse direct-current bias is applied to the disk. The pulse direct-current bias has a mean voltage of −700 to −150 V, preferably −350 to −150 V, and a positive voltage peak value of 10 to 100 V, preferably 20 to 75 V.
In the process, a hydrocarbon source is selected from lower saturated hydrocarbons, lower unsaturated hydrocarbons, and lower cyclic hydrocarbons. Of these, one or more species are preferably used.
The magnetic recording medium according to the present invention comprises a non-magnetic substrate on which a non-magnetic undercoat film and a magnetic film are formed, and a hydrogenated carbon protective film which is formed on the magnetic film through a plasma CVD method making use of a reaction gas containing a hydrocarbon serving as a raw material, wherein the density of the protective film is 2.2 g/cm
3
or more.
The hydrogenated carbon protective film may be formed on the outermost surface of the magnetic recording medium.
The production process for a magnetic recording medium according to the present invention comprises forming a fluorinated carbon protective film on a disk through a plasma CVD method making use of a reaction gas containing an organic fluorine compound serving as a raw material, which disk comprises a non-magnetic substrate on which a non-magnetic undercoat film and a magnetic film are formed, and the protective film has a density of 2.0 to 2.6 g/cm
3
.
When the fluorinated carbon protective film is formed, pulse direct-current bias is imparted to the disk. The pulse direct-current bias has a mean voltage of −400 to −100 V, preferably −350 to −100 V, and a positive voltage peak value of 10 to 100 V, preferably 20 to 75 V.
In the process, a lower saturated organic fluorine compound, a lower unsaturated organic fluorine compound, or both are preferably used as the organic fluorine compound.
The magnetic recording medium according to the present invention comprises a non-magnetic substrate on which a non-magnetic undercoat film and a magnetic film are formed, and a fluorinated carbon protective film which is formed on the magnetic film through a plasma CVD method making use of a reaction gas containing an organic fluorinated compound serving as a raw material, wherein the density of the protective film is 2.0 to 2.6 g/cm
3
.
The fluorinated carbon protective film may be formed on the outermost surface of the magnetic recording medium.
REFERENCES:
patent: 5275850 (1994-01-01), Kitoh et al.
Miyamoto Noriyuki
Shimaoka Emi
Suzuki Mikio
Takagi Kimie
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