JPS6344316A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability by providing an amorphous protective film layer on a magnetic layer by the combination of respective atoms; carbon atom, oxygen atom, hydrogen atom, and fluorine atom, and depositing the protective film layer securely onto the magnetic layer. CONSTITUTION:The amorphous protective film layer 11 which consists of the respective atoms; carbon atom, oxygen atom and hydrogen atom or said atoms and the fluorine atoms or the respective atoms; carbon atom, oxygen atom and fluorine atom, and contains the oxygen atom at the ratio higher in the boundary layer with the magnetic layer 10 than in the surface layer is formed. The protective film layer 11 formed in such a manner is satisfactorily improved in the adhesiveness to the magnetic layer by the oxygen atom contained much in the boundary layer and the protective film layer 11 is securely deposited on the magnetic layer 10, by which the durability is additionally improved without generating the worn powder by the defective adhesion and the exfoliation, etc., of the protective film layer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium with excellent durability.

[Conventional technology]

Generally, metals or their alloys are deposited on a base film by vacuum evaporation, sputtering, etc.
Alternatively, magnetic recording media made by bonding magnetic powder together with a binder component onto a base film are susceptible to abrasion of the magnetic layer due to violent sliding contact with a magnetic head etc. during recording and reproduction. Although the magnetic metal thin film layer has characteristics suitable for high-density recording, it has a large coefficient of friction with the magnetic head and is susceptible to wear and damage.

For this reason, durability has traditionally been improved by providing various protective film layers on the magnetic layer. A film layer is provided on the magnetic layer (JP-A-53-143206, JP-A-59-1)
No. 27232) has been proposed.

[Problem that the invention seeks to solve]

However, such a protective film layer mainly composed of carbon has poor adhesion to the magnetic layer, and when used for a long period of time, abrasion particles are generated and the protective film layer peels off from the magnetic layer. Sufficient durability has not been achieved.

[Means for solving problems]

This invention was made as a result of extensive research in view of the current situation, and it was discovered that carbon atoms, oxygen atoms, and hydrogen atoms, or these atoms and fluorine atoms, or carbon atoms and oxygen atoms, or carbon atoms and oxygen atoms, By providing an amorphous protective film layer consisting of fluorine atoms and fluorine atoms, and with a higher content of oxygen atoms in the interface layer with the magnetic layer than in the surface layer, the adhesiveness of the protective #i film layer to the magnetic layer is improved. The magnetic layer has improved properties and a protective film layer is firmly adhered to the magnetic layer to sufficiently improve durability.

In this invention, the protective film layer deposited on the magnetic layer is first treated with a hydrocarbon compound 7-mer gas in a treatment tank.
Alternatively, a monomer gas of a fluorine-based organic compound, a mixed gas thereof, or a mixed gas of these and fluorine gas, etc., is introduced together with oxygen gas into a glow discharge using high frequency waves or microwaves, etc., and a decomposition or polymerization reaction is caused. Carbon, oxygen, and hydrogen atoms are deposited on the magnetic layer, or sputtered with graphite, Teflon, etc. in a mixed gas atmosphere of rare gas and oxygen gas, and deposited on the magnetic layer. An amorphous protective film layer is formed of atoms, or these atoms and fluorine atoms, or carbon atoms, oxygen atoms, and fluorine atoms, and contains a relatively large amount of oxygen atoms, and then,
A protective film layer is formed in a similar manner without using oxygen gas, and an amorphous protective film layer that does not contain or contains a small amount of oxygen atoms is laminated. The content of oxygen atoms in the interface layer between the protective film layer and the magnetic layer formed in this way can be adjusted by adjusting the gas flow rate and gas pressure of oxygen gas, and by adjusting the power of high frequency or microwave during glow discharge. controlled by controlling.

In this way, if the surface layer is composed of carbon atoms, oxygen atoms, and hydrogen atoms, or these atoms and fluorine atoms, or carbon atoms, oxygen atoms, and fluorine atoms, and the content of oxygen atoms is In comparison, when an amorphous protective film layer is formed, which has a large number of atoms at the interface with the magnetic layer, the adhesion with the magnetic layer is sufficiently improved due to the oxygen atoms contained in the interface layer, and the protective film layer is formed on the magnetic layer. firmly adhered to,
Durability is further improved without generation of abrasion powder due to poor adhesion or peeling of the protective film layer.

Examples of hydrocarbon compound gases used to form such a protective film layer by glow discharge include CH4, C2H4, C2H5, C3He, C
S Hs etc. are preferably used, and as the fluorine-based organic compound 7mer gas, for example, C
F4, c2F4, C2Fs, C3F6, etc. are preferably used. In addition, mixed gases of these gases and mixed gases of these gases and hydrogen gas or fluorine gas are also preferably used.

Furthermore, graphite, Teflon, and the like are preferably used as targets for forming by sputtering. This sputtering is usually
It is carried out in a rare gas such as argon gas or neon gas, and when oxygen atoms are contained, oxygen gas is mixed with these rare gases.

In this way, when forming the protective film layer by glow discharge, the gas pressure and the high frequency or microwave power are set within the range of 0.001 to 1 Torr, and the high frequency power per square senna is set at 0.001 Torr. Preferably, the microwave power is within the range of 0.05 to 2 W/CIII, the gas pressure is 0.005 to 0.05 Torr, and the high frequency power per square centimeter is within the range of 0.05 to 2 W/CIII. 0.1~IW
/cd, the microwave power is 0.1 to IW/
More preferably, it is within the range of cd.

In addition, when forming a protective film layer by sputtering, the gas pressure and high frequency power are 0.005~
Preferably, the high frequency power per square centimeter is within the range of 0.05 to 2 W/ant, the gas pressure is 0.01 to 0.1 Torr, and the high frequency power per square centimeter is within the range of 0.05 to 2 W/ant. It is more preferable that the high frequency power is within the range of 0.1 to IW/c+d.

The thickness of the protective film layer formed in this way is 20~
It is preferably within the range of 1,000 people; if it is too thin, the durability improvement effect of this protective film layer will not be fully exhibited, and if it is too thick, the spacing loss will increase, which will have a negative impact on the electromagnetic conversion characteristics. There is a risk. In addition, oxygen atoms, which are more abundant in the interface layer with the magnetic layer than in the surface layer, are as follows: The atomic ratio is 0.
It is preferable that the content is 0.5 times or more. Further, the content of carbon atoms in this protective film layer is 0.4 to 0.0 in atomic ratio with respect to the total amount of all atoms constituting the protective film layer.
The hydrogen atom content is within the range of 9 times, and the hydrogen atom content is 0.05 to 0 in atomic ratio with respect to the total amount of all atoms constituting the protective film layer.
．． It is preferable that the content of fluorine atoms is within the range of 3 times, and the content of fluorine atoms is within the range of 0.03 to 0.2 times in atomic ratio with respect to the total amount of all atoms constituting the protective film layer. is preferred.

The magnetic layer formed on the substrate is made of r-Fe203 powder, F
e3O4 powder, Co-containing r-Fe203 powder, Co-containing Fe3O4 powder, Fe powder, CO powder, Fe-Ni
Magnetic powder such as powder is coated on a substrate together with a binder component and an organic solvent and dried, or Co, Fe
, Ni, Co-Ni alloy, Go-Cr alloy, Co-P
It is formed by depositing a ferromagnetic material such as alloy, Co--N1--P alloy, etc. on the substrate by means such as vacuum evaporation, ion blasting, sputtering, plating, or the like.

In addition, as magnetic recording media, polyester film,
Various types of structures that come into sliding contact with magnetic heads, such as magnetic tapes based on synthetic resin films such as polyimide films, magnetic disks and magnetic drums based on disks and drums made of synthetic resin films, aluminum plates, glass plates, etc. includes.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10 μm was placed in a vacuum evaporation apparatus, and 20 μm of oxygen gas was added under a vacuum of 1X10-5 torr.
Cobalt was introduced at a flow rate of 0 seconds and then heated to evaporate to form a ferromagnetic metal thin film layer of 1000 nm thick on the polyester film. Then the first
Using the glow discharge treatment apparatus shown in the figure, a polyester film 1 on which a ferromagnetic metal thin film layer was formed was set in a treatment tank 2 so as to be wound up from a supply roll 3 to a take-up roll 4. Next, while running the polyester film 1 at a speed of 5 m/min, CH4 gas was introduced at a flow rate of 100 seconds and oxygen gas was introduced at a flow rate of 53 seconds from the gas introduction pipe 5 attached to the processing tank 2 to bring the total gas pressure down. 0.
005 toll, and a 13.56 MHz
A high frequency wave was applied at a power density of 0.2 W/cJ to generate a glow discharge to form a protective film layer with a thickness of 30 mm. Next, the polyester film 1 with this protective film layer formed thereon is moved from the take-up roll 4 to the supply roll 3 side for 3 m.
CH4 from the gas introduction pipe 5 while running at a speed of /min.
Gas was introduced at a flow rate of 30 sec, and the gas pressure was set to 0.00.
5 I made it to Thor. and 13.56 M to the lower electrode 6
Hz high frequency with a power density of 0.5W/CIl! Apply with
A glow discharge was generated to form a protective film layer with a thickness of 70 μm, making the total thickness of the protective film layer 100 μm. After that,
A ferromagnetic metal thin film layer 10 and a protective H* layer 1 are placed on a polyester film 1 cut to a predetermined width as shown in FIG.
A magnetic tape A was prepared by sequentially laminating the magnetic tapes 1 and 2. In FIG. 1, 7 is an upper electrode disposed directly above the polyester film 1 moving between the supply roll 3 and the take-up roll 4, 8 is an exhaust system for reducing the pressure inside the processing tank 2, and 9 is an exhaust system. This is a high frequency power source for applying high frequency to the lower electrode 6. When the protective film layer on the magnetic tape thus obtained was examined by high-sensitivity reflection infrared absorption spectroscopy, the property of the protective film layer was found to be amorphous. In addition, while etching the elemental composition of this protective film layer with Ar ions, ESC
When investigated by A and SIMS, on the outermost surface,
The atomic ratio of C:0:H is 1:0.02:0.0
8, and C:O:H is 20 at the interface with the magnetic layer.
: It was 0.12.

Example 2 A ferromagnetic metal was deposited on a polyester film in the same manner as in Example 1. #A film layer is formed, and then, using the glow discharge treatment apparatus shown in FIG. , and was set so as to be wound onto a winding roll 15 disposed in the other processing tank 14.

Next, while running the polyester film 1 at a speed of 4 m/min, the gas introduction pipe 16 attached to the processing tank 12 is
02F4 gas was introduced at a flow rate of 100 sec, and oxygen gas was introduced at a flow rate of 20 sec, and the total gas pressure was reduced to 0.0.
1 to the lower electrode 17 disposed directly under the polyester film 1 running in the processing tank 12.
．． 56 MHz high frequency power density 0.3W/CI+1
was applied to generate a glow discharge. At the same time, processing tank 1
Inject 200% CH4 gas from the gas introduction pipe 18 attached to 4.
A gas of 13.56 MH was introduced at a flow rate of 13.56 secm, and the gas pressure was set to 0.04 1-rel, to the lower mold i19 disposed directly below the polyester film 1 running in the processing tank 14.
z high frequency with a power density of 0.6W/cn! Apply with
A glow discharge was generated to form a protective film layer with a thickness of 110 mm. Thereafter, it was cut to a predetermined width to produce magnetic tape A as shown in FIG. In addition, 20.21 in Figure 3
22.23 is an upper electrode disposed directly above the polyester film 1 moving between the supply roll 13 and the take-up roll 15, 22.23 is an exhaust system for reducing the pressure inside the processing tank 12.14, and 24.25 is an exhaust system. This is a high frequency power source for applying high frequency to the lower electrodes 17 and 19. When the protective film layer of magnetic tape A thus obtained was examined by high-sensitivity reflection infrared absorption spectroscopy, the property of the protective film layer was amorphous. Furthermore, when the elemental composition of this protective film layer was investigated in the same manner as in Example 1, the atomic ratio of C:0:H on the outermost surface was 1:0.03:0.07, which was similar to that of the magnetic layer. At the interface, C:O:F is l: 0.25
: It was 0.07.

Example 3 In forming the protective film layer in Example 1, instead of introducing CH4 gas, a graphite target was placed on the upper electrode 7, and Ar gas and oxygen gas were introduced from the gas introduction tube 5 at flow rates of 50 sc+n and 30 sccra, respectively. A high frequency of 13.56 MHz was applied to the upper electrode 7 at a power density of 0.7 W/c.
Sputtering was performed by applying a voltage of d to form a protective film layer with a thickness of 30 mm. Next, the polyester film 1 on which the protective film layer was formed was run at a speed of 4 m/min from the take-up roll 4 to the supply roll 3 side, and Ar gas was introduced from the gas introduction pipe 5 at a flow rate of 101005e. pressure to 0
．． 01 toll and 13.56 M to the upper electrode 7
Sputtering was performed by applying H2 high frequency at a power density of 0.9 W/cd to form a protective film layer with a thickness of 70 nm, making the total thickness of the protective film layer 100 nm. Thereafter, it was cut to a predetermined width to produce magnetic tape A as shown in FIG. When the protective film layer of magnetic tape A thus obtained was examined by high-sensitivity reflection infrared absorption spectroscopy, the property of the protective film layer was amorphous. Further, when the elemental composition of this protective film layer was investigated in the same manner as in Example 1, it was found that on the outermost surface, the atomic ratio of C:O:H was 1:0.02.
: 0.01, and at the interface with the magnetic layer, C:○:H was InO,10:0.04.

Example 4 Same as Example 1 except that in forming the protective film layer in Example 1, the same amount of mixed gas of CH and CF gas mixed at a volume ratio of 1:1 was used instead of CH gas. Magnetic tape A was produced by forming amorphous protective film layers with a total thickness of 70 and 30 and 40 layers, respectively. When the elemental composition of the protective film layer of the magnetic tape A, which had been thickened by one layer in this manner, was investigated in the same manner as in Example 1, the atomic ratio of C:O:H:F was x:o, o2 on the outermost surface.
: 0.04: 0.04, and at the interface with the magnetic layer, C:○:H:F is 1: 0.10: 0.20.
: It was 0.20.

Example 5 α-Fe @ powder 600 parts by weight S-LEC CN (manufactured by Ta Mizu Kagaku Kogyo 80, vinyl chloride)
(Vinyl acetate copolymer) Bandesox T-5250 (30% manufactured by Nippon Ink Chemical Industries, Ltd., urethane elastomer) Coronate Shiku Nippon Polyurethane 10% manufactured by Nippon Ink Industries, Ltd.
Trifunctional low molecular weight isocyanate compound) Methyl isobutyl ketone 400〃Toluene
400 This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint, and this magnetic paint was applied onto a polyester film with a thickness of 10 μm to a dry thickness of 4 μm, and dried to form a magnetic layer. did.

Next, an amorphous protective film layer was formed thereon in the same manner as in Example 1 to produce a magnetic tape.

Comparative Example 1 In the formation of the protective film layer in Example 1, the traveling speed of the polyester film 1 on which the ferromagnetic metal thin film layer was formed from the supply roll 3 to the take-up roll 4 side was set at 4 m/min.
The gas introduced from the gas introduction pipe 5 was changed from a mixed gas of CH4 gas and oxygen gas to CH4 gas, and the gas was introduced at a flow rate of 3Q sccm, and the gas pressure was reduced to 0.
．． 005 I made it to Thor. Also, the lower electrode 6 has 13.5
6 MHz high frequency with power density 0, 5 W/ci
was applied to generate a glow discharge to form an amorphous protective film layer with a thickness of 70 mm, and the polyester film 1 with this protective film layer formed thereon was run reversely from the winding roll 4 to the supply roll 3 side. A magnetic tape was produced by forming a protective film layer in the same manner as in Example 1, except that the formation of the protective film layer was omitted. When the elemental composition of the protective film layer of the magnetic tape thus obtained was investigated in the same manner as in Example 1, it was found that both the outermost surface and the interface with the magnetic layer had an atomic ratio of C:
O:H was 1:0.02:0.08.

Comparative Example 2 In forming the protective film layer in Example D113, the gas introduced from the gas introduction pipe 5 was changed from a mixed gas of Ar gas and oxygen gas to Ar gas, and the gas was introduced at a flow rate of 101005e, and the gas pressure was set to 0. 01 Thor and upper electrode 7 1
3.56 MHz high frequency with power density 0.9W/cnl
A magnetic tape was produced in the same manner as in Example 3, except that an amorphous protective film layer having a thickness of 70 mm was formed by applying an electric current at 100 nm and performing sputtering. When the elemental composition of the protective film layer of the magnetic tape thus obtained was investigated in the same manner as in Example 1, the atomic ratio of C:O:H was 1:0 both on the outermost surface and at the interface with the magnetic layer. .02: 0.01
Met.

Regarding the magnetic tapes obtained in each example and comparative example,
The still life was measured using a commercially available 8 mm VTR device, a still test was conducted, and the durability was evaluated.

The table below shows the four antagonists.

〔Effect of the invention〕

As is clear from the above table, the magnetic tapes obtained in this invention (Examples 1 to 5) are the same as Comparative Examples 1 and 2.
This shows that the magnetic recording medium obtained by the present invention has a longer still life than the magnetic tape obtained by the present invention.

[Brief explanation of drawings]

Figure 1 shows a glow discharge treatment device used to form a protective film layer made of an amorphous organic polymer compound.
A schematic cross-sectional view showing an example, FIG. 2 is a partially enlarged cross-sectional view of a magnetic tape obtained by the manufacturing method of the present invention, and FIG. 3 is used when forming a protective film layer made of an amorphous organic polymer compound. FIG. 2 is a schematic cross-sectional view showing another example of a glow discharge treatment apparatus. DESCRIPTION OF SYMBOLS 1... Polyester film (substrate), 10... Ferromagnetic metal thin film layer (magnetic material), 11... Protective film layer, A...
・Magnetic tape (magnetic recording medium) Patent applicant Hitachi Maxell Ltd. Figure 1

Claims (1)

[Claims] 1. A magnetic layer is formed on a substrate, and on this magnetic layer, a magnetic layer consisting of carbon atoms, oxygen atoms, and hydrogen atoms, or these atoms and fluorine atoms, or carbon atoms, oxygen atoms, and fluorine atoms is formed. , and an amorphous protective film layer in which the content of oxygen atoms is greater in the interface layer with the magnetic layer than in the surface layer.