JPH076354A - Magnetic recording medium and production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the ferromagnetic metallic thin film type magnetic recording medium capable of compatibly attaining high electromagnetic conversion characteristics and practicable reliability (traveling stability, durability and wheatherability) with higher order. CONSTITUTION:A ferromagnetic metallic thin film 3 is formed on a nonmagnetic substrate 1 and a hard carbon film 5 is formed on this ferromagnetic metallic thin film 3. A reforming surface 6 which contains carbon, nitrogen and oxygen, has >=0.8% atomic ratio of nitrogen to carbon and <3nm thickness is formed on this hard carbon film 5; further, a lubricant layer 7 is formed on this reforming surface 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic metal thin film type magnetic recording medium used in a VTR, a magnetic disk device, etc., and particularly to achieve a high degree of compatibility between electromagnetic conversion characteristics and practical reliability. The present invention relates to a magnetic recording medium in which a protective film and a lubricant layer are sequentially formed on a layer.

[0002]

2. Description of the Related Art In recent years, magnetic recording devices have been required to have a large capacity, a high speed, a high image quality and a high sound quality, a small size and a light weight. Accordingly, it is indispensable for the magnetic recording medium to achieve high-density recording, and the residual magnetic flux density (Br) of the magnetic layer is different from that of the conventional coating type magnetic recording medium in which a magnetic material is dispersed in a binder. And coercive force (Hc)
Both of them are large, the magnetic layer can be thinned, and a ferromagnetic metal thin film type magnetic recording medium which is optimal for super smoothing of the magnetic layer surface is actively developed and put to practical use.

However, the magnetic layer of the ferromagnetic metal thin film type magnetic recording medium has a low hardness and is easily plastically deformed. Therefore, when the magnetic layer of the VTR rotating at a high speed and the metal cylinder are directly contacted with each other, the magnetic layer is momentarily worn. There is a problem that the head is damaged and causes metal adhesion on the sliding surface of the head, resulting in deterioration of durability (a large decrease in recording / reproducing output due to repeated running, a marked decrease in still life, etc.). Further, although the surface of the magnetic layer is protected by forming an oxide film, there is a problem that the corrosion resistance in a high humidity environment is insufficient.

Therefore, conventionally, in order to improve the lubricity, wear resistance and corrosion resistance of a ferromagnetic metal thin film type magnetic recording medium, a base film having minute projections is used,
It has been proposed to form a protective film or a fluorine-containing lubricant layer having a slippery and water-repellent effect on the magnetic layer. Especially for the protective film, in order to reduce the spacing loss between the magnetic layer and the magnetic head, it is necessary to set the thickness of the protective film to a small value. There are many proposals for the structure to be formed (for example, described in JP-A-61-210518 and JP-A-63-98824).

Further, in JP-A-1-245417 and JP-A-2-158909, a diamond-like carbon film is formed on a magnetic layer, and a lubricant layer (fluorine-containing fatty acid layer) is further formed on the diamond-like carbon film. ) Is disclosed.

However, it is very difficult to provide a magnetic recording medium which is sufficiently satisfied in running stability and durability by using the method conventionally used, and various problems have occurred.

For example, when only the fluorine-containing lubricant layer is formed on the magnetic layer, the shearing force can be reduced, but the hardness of the medium surface is low and the medium is easily worn, so that the running stability is deteriorated. , The result is that the still life is reduced.

When only a hard protective film (for example, a diamond-like carbon film) is formed on the magnetic layer, the protective film itself causes brittle fracture due to direct contact with the magnetic head and the metal cylinder of the VTR rotating at a high speed. As a result, the still life is significantly reduced, and the stability of the reproduction output during repeated running cannot be ensured.

Further, even when a high hardness diamond-like carbon film and a lubricant layer are sequentially formed on the magnetic layer, the surface state of the diamond-like carbon film is chemically very inactive, so that Has insufficient adhesion,
There were problems such as seizure of a lubricant component on the head sliding surface during recording and reproduction, resulting in a significant reduction in output, and head clogging for a long time.

Therefore, recently, in order to improve the adhesion between the protective film and the lubricant layer, a hard carbon protective film, a nitrogen-containing plasma polymerized film, and a lubricant layer containing a fluorine-containing carboxylic acid are formed on the ferromagnetic metal thin film. Structure of sequentially forming
No. 7), a protective film layer made of an organic polymer compound containing at least carbon atoms and nitrogen atoms is provided on a ferromagnetic metal thin film layer, and a lubricant layer is further formed on this protective film layer (special feature (Kaisho 62-58416), a hard carbon thin film containing B or Ti or Si is formed on a ferromagnetic metal thin film, and then a lubricant layer having a reactive group is continuously disposed by a vacuum deposition method ( JP-A-1-184722), Mn, Mo, Nb, Ta, T on a magnetic metal thin film.
A structure in which a protective film containing, as a main component, graphite-like carbon containing at least one selected from i, V and W is provided, and then a lubricating layer containing an organic compound having a mercapto group as a main component is formed (Japanese Patent Laid-Open No. Sho 63-63). No. 177,312) has been proposed.

Further, Japanese Patent Laid-Open No. 2-126418 discloses that
A configuration is disclosed in which a hard carbon film is formed on a ferromagnetic metal thin film, the surface of the hard carbon film is subjected to glow discharge treatment with ammonia gas, and a lubricant layer containing a fluorine-containing carboxylic acid is further formed.

[0012]

However, even with the above structure, it is difficult to provide a magnetic recording medium having excellent electromagnetic conversion characteristics and durability, and there are still many problems.

For example, in the structure in which the nitrogen-containing plasma polymerized film is formed at the interface between the hard carbon protective film and the lubricant layer, the hardness of the nitrogen-containing plasma polymerized film is low and it is easily worn, so that the running stability and durability are sufficiently improved. Can't be satisfied. on the other hand,
When the film thickness of the nitrogen-containing plasma polymerized film is set to be large in order to improve the wear resistance, the spacing loss between the magnetic layer and the magnetic head increases, and the electromagnetic conversion characteristics deteriorate.

Further, in the structure in which the lubricant layer is formed on the protective film containing N, B, Ti, Si, metal or the like, the adhesion between the protective film and the lubricant is improved, but the hardness of the protective film itself. Therefore, there is a problem that durability such as still life deteriorates.

Further, in the structure in which the lubricant layer is formed after the surface of the hard carbon protective film is subjected to glow discharge treatment with ammonia gas, the surface of the hard carbon protective film is remarkably affected by the impact of charged particles generated from ammonia which is a non-polymerizable gas. Since it is damaged, it has a problem that durability and weather resistance are significantly deteriorated.

The present invention is intended to solve the above problems,
It is an object of the present invention to provide a ferromagnetic metal thin film type magnetic recording medium capable of achieving a high level of compatibility between electromagnetic conversion characteristics and practical reliability.

[0017]

To achieve the above object, the first invention is to form a ferromagnetic metal thin film on a non-magnetic substrate, and form a hard carbon film on the ferromagnetic metal thin film. A modified surface having a thickness of less than 3 nm containing carbon, nitrogen and oxygen and having an atomic ratio of nitrogen to carbon of 0.8% or more is formed on the hard carbon film, and a lubricant layer is further formed on the modified surface. Are formed.

In the second aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and the hard carbon film contains carbon, nitrogen and oxygen. ,
Thickness 3 where the atomic ratio of nitrogen to carbon is 0.8% or more and the nitrogen concentration decreases from the outermost surface in the depth direction.
A modified surface of less than nm is formed, and a lubricant layer is further formed on the modified surface.

According to a third aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate having protrusions, and a hard carbon film having an uneven surface corresponding to the protrusions is formed on this ferromagnetic metal thin film.
On this hard carbon film, an island-shaped modified surface containing carbon, nitrogen and oxygen and having an atomic ratio of nitrogen to carbon of 0.8% or more and a thickness of less than 3 nm is formed. A lubricant layer is formed on the base material.

According to a fourth aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, and a peak existing near 1380 cm ^-1 of Raman spectrum on this ferromagnetic metal thin film is (A), and 1550 cm. ^{The peak} existing near ^{-1 is} defined as (B), and the area of (A) when fitting the Gaussian curve to the peaks of (A) and (B) is divided by the area of (B). Value (area intensity ratio of Raman spectrum) is 0.8
To 3.0 and the density is 1.5 g / cm ³ or more, a hard carbon film is formed, and carbon, nitrogen, and oxygen are contained on the hard carbon film, and the atomic ratio of nitrogen to carbon is 0.8%. The modified surface having a thickness of less than 3 nm is formed, and the lubricant layer is further formed on the modified surface.

In the fifth aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, and a peak existing near 1380 cm ^-1 of the Raman spectrum on the ferromagnetic metal thin film is (A), and 1550 cm. ^{The peak} existing near ^{-1 is} defined as (B), and the area of (A) when fitting the Gaussian curve to the peaks of (A) and (B) is divided by the area of (B). Value (area intensity ratio of Raman spectrum) is 0.8
~ 3.0, the density is 1.5 g / cm ³ or more,
A hard carbon film having a Vickers hardness of 2000 kg / mm ² or more is formed, and a lubricant layer is further formed on the hard carbon film.

According to a sixth aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and the surface of the hard carbon film is treated with a nitrogen-containing organic gas. This is a method of manufacturing a magnetic recording medium in which a lubricant layer is formed after forming a modified surface by exposing it to glow discharge plasma with a mixed gas with an inorganic gas.

According to a seventh aspect of the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and the surface of the hard carbon film is treated with a nitrogen-containing organic gas. This is a method for producing a magnetic recording medium in which a lubricant layer is formed after forming a reformed surface by exposing it to glow discharge plasma with a mixed gas of a hydrocarbon-based gas and an inorganic gas.

[0024]

According to the first invention and the sixth invention,
Since a modified surface having a thickness of less than 3 nm containing a suitable amount of a nitrogen atom having a strong chemical affinity with a polar group introduced into a lubricant molecule is formed on a hard carbon film, Without reducing the hardness of the protective film consisting of the modified surface,
Moreover, the lubricant molecules can be firmly held on the tape surface without increasing the spacing loss between the ferromagnetic metal thin film and the magnetic head. Further, in order to form a modified surface on the hard carbon film, by applying a method of exposing the hard carbon film surface to glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured. Therefore, a synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, so that a magnetic recording medium excellent in electromagnetic conversion characteristics, running stability, durability, and weather resistance is provided. It becomes possible to do.

According to the second and seventh aspects of the present invention, modification having a thickness of less than 3 nm containing a proper amount of nitrogen atoms having a strong chemical affinity with the polar group introduced into the lubricant molecule. Since the surface is formed on the hard carbon film, it is possible to increase the spacing loss between the ferromagnetic metal thin film and the magnetic head without lowering the hardness of the protective film consisting of the hard carbon film and the modified surface. Without it, the lubricant molecules can be firmly held on the tape surface. Furthermore, since the nitrogen concentration on the modified surface decreases from the outermost surface in the depth direction (toward the interface with the hard carbon film), the internal stress of the modified surface itself is moderate. Can be relaxed to
Moreover, by applying a method of exposing the hard carbon film surface to a glow discharge plasma by a mixed gas of a nitrogen-containing organic gas, a hydrocarbon gas, and an inorganic gas in order to form a modified surface on the hard carbon film, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning the hard carbon film surface, it is possible to further improve the adhesion between the hard carbon film and the modified surface. Therefore, a synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, so that a magnetic recording medium excellent in electromagnetic conversion characteristics, running stability, durability, and weather resistance is provided. It becomes possible to do.

According to the third and sixth aspects of the present invention, island-like particles having a thickness of less than 3 nm containing a suitable amount of nitrogen atoms having a strong chemical affinity with the polar group introduced into the lubricant molecule. Since the modified surface is formed on the hard carbon film, the magnetic properties of the VTR rotating at a high speed without lowering the hardness of the protective film itself and without increasing the spacing loss between the magnetic layer and the magnetic head. Lubricant molecules can be firmly held at the tip of the tape protrusion that makes actual contact with the head, the metal cylinder, the guide post, and the like. Further, by applying a method of exposing the hard carbon film surface to glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas in order to form an island-shaped modified surface on the hard carbon film,
Since the chemically activated species (reactive species) in the plasma can be deposited while cleaning the surface of the hard carbon film, it is possible to secure good adhesion between the hard carbon film and the island-shaped modified surface. . Therefore, a synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, so that a magnetic recording medium excellent in electromagnetic conversion characteristics, running stability, durability, and weather resistance is provided. It becomes possible to do.

According to the fourth invention and the sixth invention, the hard carbon film formed on the ferromagnetic metal thin film is SP ³
It is a continuous film that has a high hardness and a dense structure mainly composed of bonds, and further contains a suitable amount of nitrogen atoms having a strong chemical affinity with the polar group introduced into the lubricant molecule, and has a thickness of less than 3 nm. Since the modified surface is formed on the hard carbon film described above, the hardness of the protective film composed of the hard carbon film and the modified surface is not reduced, and the spacing loss between the ferromagnetic metal thin film and the magnetic head is reduced. The lubricant molecules can be firmly held on the tape surface without increasing the temperature.
Further, in order to form a modified surface on the hard carbon film, by applying a method of exposing the hard carbon film surface to glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured. Therefore, a synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, so that a magnetic recording medium excellent in electromagnetic conversion characteristics, running stability, durability, and weather resistance is provided. It becomes possible to do.

According to the fifth aspect of the present invention, the hard carbon film formed on the ferromagnetic metal thin film is a continuous film mainly composed of SP ³ bonds and having a high hardness and a dense structure. It is possible to provide an excellent magnetic recording medium.

[0029]

【Example】

(Embodiment 1) Hereinafter, embodiments of the first and sixth aspects of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an enlarged sectional view showing the structure of the ferromagnetic metal thin film type magnetic tape of the first invention. In the figure, 1 is a non-magnetic substrate, and a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyamide or polyimide can be used, and the maximum height roughness (Rmax) is 10 nm on the substrate surface on the magnetic layer side. The minute protrusion layer 2 having a thickness of about 30 nm is formed. Reference numeral 3 is a ferromagnetic metal thin film, which is used to heat and evaporate a metal or alloy such as Co and Co-Ni with an electron beam in a vacuum atmosphere, and continuously inject it while introducing a slight amount of oxygen gas into the vacuum chamber. It is formed by the oblique evaporation method with the angle changed. The film thickness is 150 nm
~ 200 nm. 4 is a back coat layer, which is formed by applying and drying a paint containing carbon black, calcium carbonate, a polyester resin, and a nitrocellulose resin as main components. Its film thickness is about 500 nm. Reference numeral 5 is a hard carbon film, which can be formed by a plasma CVD method or the like, and its film thickness is optimally 8 nm to 15 nm in order to secure reproduction output in the short wavelength region. 6 is a modified surface, which is formed by exposing the surface of the hard carbon film 5 to glow discharge plasma of a mixed gas of a nitrogen-containing organic gas and an inorganic gas. Its thickness is less than 3 nm. Reference numeral 7 denotes a fluorine-containing lubricant layer having a polar group such as a carboxyl group introduced into the molecule, which is formed by a wet coating method or an organic vapor deposition method and has a film thickness of about 3 nm.

FIG. 2 shows a film forming apparatus for forming the hard carbon film 5 and the modified surface 6 which compose the ferromagnetic metal thin film type magnetic tape of the first invention by the plasma CVD method. It is a schematic diagram. In the figure, 8 is a vacuum tank, and the pressure inside the vacuum tank 8 is 10 ⁻⁴ using a vacuum pump 9.
Evacuation is performed so that a high vacuum state of torr to 10 ⁻⁵ torr is obtained. Reference numeral 10 denotes a metal thin film type magnetic tape stock in which a ferromagnetic metal thin film 3 and a back coat layer 4 are formed on a non-magnetic substrate 1, which is fed from an unwinding roll 11 and two pass rolls 12, 13 and a cylinder It is wound on the winding roll 15 via the outer peripheral surface of the cooling can 14. The cooling can 14 has a function of controlling rotation so that the metal thin film magnetic tape stock 10 can be conveyed at a constant speed.

Reference numeral 16 denotes a discharge tube (non-equilibrium plasma generating space) for forming the hard carbon film 5 on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape stock 10.
A pipe-shaped discharge electrode 17 is installed inside the unit 6. The pipe-shaped discharge electrode 17 is a power source 18 for plasma generation.
The plasma generating power source 18 is connected to
Method of applying only either DC voltage or AC voltage or method of applying DC voltage and AC voltage in a superimposed manner
Different types of discharge methods can be adopted. Reference numeral 19 is a raw material gas inlet for introducing a mixed gas (raw material gas) of a hydrocarbon type gas and an inorganic type gas such as argon into the discharge tube 16.

Reference numeral 20 denotes a discharge tube (non-equilibrium plasma generation space) for forming the modified surface 6 on the hard carbon film 5, and a punching metal discharge electrode 21 is installed inside the discharge tube 20. . The punching metal discharge electrode 21 is connected to a plasma generating power source 22. As the plasma generating power source 22, a method of applying only a DC voltage or an AC voltage or a method of superimposing a DC voltage and an AC voltage is used. It is possible to adopt three types of discharge methods of applying. Reference numeral 23 denotes a raw material gas inlet for introducing a mixed gas (raw material gas) of a nitrogen-containing organic gas and an inorganic gas into the discharge tube 20.

Example 1-1 Surface roughness analysis by a scanning tunneling microscope (STM) showed a maximum height roughness (R _max ) of 15 nm and a diameter of 200 n.
The micro-projection layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of CoNiO having a film thickness of 180 nm is formed on the surface of each of the polyethylene terephthalate films 1 having a thickness of 10 μm by the continuous incident angle changing vapor deposition method.
Form. After that, a back coat layer 4 is formed to a thickness of 500 nm on the opposite surface of the polyethylene terephthalate film 1 by a wet coating method.

Next, the metal thin film magnetic tape stock 10 is installed inside the vacuum chamber 8 of the film forming apparatus shown in FIG.
After evacuating the interior, hexane gas (hydrocarbon gas: C ₆ H ₁₄ ) and argon gas (inorganic gas: Ar) were introduced into the discharge tube 16, respectively, and the pressure ratio of hexane gas and argon gas was changed. 4: 1, total gas pressure 0.3 torr
The gas flow rate is adjusted to be r. In addition, the discharge tube 20
Pyridine gas (nitrogen-containing organic gas: C ₅ H ₅ N) and hydrogen gas (inorganic gas: H ₂ ) were introduced into the chamber, respectively, and the pressure ratio of pyridine gas and hydrogen gas was 3: 2, total gas pressure. The gas flow rate is adjusted so that is 0.1 torr. After that, the metal thin film type magnetic tape raw material 10 is 3 to 5 m / m.
By transporting at a traveling speed of in and applying a DC voltage of 1000 V to the pipe-shaped discharge electrode 17,
Non-equilibrium plasma is generated and a hard carbon film 5 is formed to a thickness of 13 nm on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape stock 10. Further punching metal discharge electrode 2
A non-equilibrium plasma is generated by applying a direct current voltage of 1500 V to 1 to form a modified surface 6 with a thickness of 1 nm on the surface of the hard carbon film 5 of the metal thin film magnetic tape stock 10.

Then, a fluorine-containing lubricant layer 7 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 6 by a wet coating method to a thickness of about 3 nm. , 8 mm width was slit to produce a metal thin film type magnetic tape for VTR of 8 mm.

The Vickers hardness of the hard carbon film 5 obtained in Example 1-1 was 2500 kg / mm ² .

Example 1-2 As a raw material gas for forming the modified surface 6, allylamine (nitrogen-containing organic gas: C ₃ H ₇ N) was used instead of pyridine.
8 mmV by the same method as in Example 1-1 except that the pressure ratio of allylamine gas and hydrogen gas is 1: 1.
A metal thin film type magnetic tape for TR was produced.

Example 1-3 The reforming surface 6 has a thickness of 2 with the pressure ratio of the pyridine gas, which is the source gas for forming the reforming surface 6, and the hydrogen gas being 1: 2 and the total gas pressure being 0.3 torr. A metal thin film magnetic tape for 8 mm VTR was produced in the same manner as in Example 1-1 except that the thickness was 0.5 mm.

Example 1-4 Argon (inorganic gas: Ar) was used instead of hydrogen as a raw material gas for forming the reformed surface 6, and the pressure ratio of the pyridine gas and the argon gas was set to 1: 3. Example 1 except
A metal thin film type magnetic tape for 8 mm VTR was produced by the same method as in -1.

Example 1-5 As a raw material gas for forming the reformed surface 6, allylamine was used instead of pyridine, ammonia (inorganic gas: NH ₃ ) was used instead of hydrogen, and allylamine gas and ammonia gas were mixed. Example 1-except that the pressure ratio is 1: 3
A metal thin film type magnetic tape for 8 mm VTR was produced by the same method as in 1.

Comparative Example 1-1 By the same method as in Example 1-1, except that benzene (hydrocarbon gas: C ₆ H ₆ ) was used instead of pyridine as a raw material gas for forming the reformed surface 6. , 8 mm VTR metal thin film type magnetic tape was produced.

Comparative Example 1-2 As the raw material gas for forming the reformed surface 6, a mixed gas of pyridine, benzene and hydrogen was used instead of the mixed gas of pyridine and hydrogen, and the pressure ratio was 1: 5: 1. A metal thin film type magnetic tape for 8 mm VTR was manufactured by the same method as in Example 1-1 except that the above was performed.

Comparative Example 1-3 Example 1-1 except that the thickness of the modified surface 6 is set to 4 nm.
A metal thin film magnetic tape for 8 mm VTR was produced by the same method as described in (1).

Comparative Example 1-4 8 m was prepared in the same manner as in Example 1-1, except that the Vickers hardness of the hard carbon film was 1300 kg / mm ^2.
A metal thin film type magnetic tape for mVTR was produced.

The chemical composition (atomic ratio) and the chemical bonding state of the modified surface 6 in Examples and Comparative Examples were determined by X-ray measurement using the metal thin film type magnetic tape stock 10 on which the fluorine-containing lubricant layer 7 was not formed. Surface analysis was performed by photoelectron spectroscopy (XPS), and the results are shown in (Table 1).

A hard carbon film having a thickness of 1 to 3 μm is formed on a silicon wafer instead of the metal thin film type magnetic tape stock 10.
Several kinds of samples having a thickness of about m were prepared, and the Vickers hardness of the above samples was measured using a micro hardness meter (micro hardness meter).
The Vickers hardness of the hard carbon film corresponding to m was calculated, and the value was set as the Vickers hardness value of the hard carbon film 5 in the examples and comparative examples. The film thickness of the hard carbon film in the above sample was a value measured by an ellipsometer. The results are shown in (Table 1).

[0048]

[Table 1]

Each 8 obtained in the above examples and comparative examples
The following measurements were performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) Head clogging, tape damage Using an 8 mm VTR modified for RF output measurement, 40 ° C
Under an environment of -80% RH, a video signal was recorded on each magnetic tape having a length of 60 minutes, and reproduction was performed for 300 passes. The time during which the reproduction output was continuously reduced by 6 dB or more during the durability test by the repeated running was accumulated, and the time was defined as the head clogging time. The tape damage was evaluated by observing the surface condition of the tape visually after the running durability test, and was evaluated in five levels. The evaluation was rated as 5 when there was no problem in practical use, and as 1 when there was a problem in practical use. (2) Change in friction coefficient (hereinafter referred to as μ _k change amount) Under normal temperature and normal humidity conditions, the friction coefficient on the magnetic layer forming surface side of each magnetic tape was measured before and after the running durability test, and the μ _k change amount was calculated. I asked. The measurement conditions are as follows.

A stainless steel (material: MH15) cylinder having a diameter of 4 mm and a surface roughness of 0.2 S was wound at a wrapping angle of 180 ° with the magnetic layer forming surface side of each magnetic tape inside, and the entrance tension was 10 g. The exit side tension Xg when the traveling speed is set to 14 mm / sec is measured, and the friction coefficient is calculated from the following equation.

[0051]

[Equation 1]

As the friction coefficient, the value measured on the 10th pass was adopted. (3) Weather resistance test As a weather resistance test, the magnetic tape was left for about 30 days in an environment of 40 ° C.-90% RH, and the state of occurrence of rust, peeling, etc. was observed with an optical microscope to perform a 5-level evaluation. . The evaluation was rated as 5 when there was no problem in practical use, and as 1 when there was a problem in practical use. (4) Dropout change (hereinafter referred to as DO change rate) Using an 8 mm VTR modified for dropout measurement,
Under normal temperature and normal humidity environment, each 60-minute long magnetic tape on which a video signal was recorded was measured for dropout (the number per minute at which an output decrease of 16 dB or more occurred for 15 μs). Furthermore, after the weather resistance test according to (3), the dropout was measured by the same method, and the D.O. change rate after the weather resistance test with respect to that before the weather resistance test was displayed as a magnification. (5) Environmental gas resistance test (H ₂ S gas, HCl gas) After leaving each magnetic tape in the air containing 1000 ppm of H ₂ S gas or HCl gas for 72 hours, the state of rust is observed with an optical microscope. Observation was carried out and the evaluation was carried out on a 5-point scale. The evaluation was rated as 5 when there was no problem in practical use, and as 1 when there was a problem in practical use.

Table 2 shows the evaluation results of the metal thin film magnetic tape for 8 mm VTR produced in each of the examples and comparative examples.

[0054]

[Table 2]

As is clear from (Table 1) and (Table 2),
The metal thin film magnetic tape of this example has a hard modified surface with a thickness of less than 3 nm that contains an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into a lubricant molecule. Since it is formed on the carbon film, the hardness of the protective film consisting of the hard carbon film and the modified surface is not reduced, and the spacing loss between the ferromagnetic metal thin film and the magnetic head is not increased, and the tape surface is not increased. Moreover, the lubricant molecules can be firmly held. Further, in order to form a modified surface on the hard carbon film, by applying a method of exposing the hard carbon film surface to glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured. Therefore, since the synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, running durability and weather resistance can be dramatically improved.

In Comparative Example 1-1, since the raw material gas for forming the modified surface on the hard carbon film does not contain the specific element (nitrogen atom) of the present invention in the molecule, Comparative Example 1-1 1
-2, since the atomic ratio of nitrogen to carbon and the atomic ratio of nitrogen to oxygen on the modified surface are below the appropriate range of the present invention, the adhesiveness between the hard carbon film and the fluorine-containing lubricant layer is low. Was not improved, resulting in deterioration of running durability and weather resistance.

In Comparative Examples 1-3, due to the chemical affinity between the nitrogen atom contained in the modified surface and the polar group (carboxyl group) introduced into the lubricant molecule, the modified surface was hardened with the intermediate layer as the intermediate layer. Although the carbon film and the lubricant layer adhere firmly, the thickness of the modified surface is too large, so the synergistic effect of the wear resistance of the hard carbon film and the low shearing force of the lubricant layer is fully exerted. However, the running durability was deteriorated.

In Comparative Example 1-4, the running durability was deteriorated because the Vickers hardness of the carbon film was low.

(Embodiment 2) A second embodiment of the present invention and a seventh embodiment of the present invention will be described in detail with reference to the drawings. The difference between this embodiment and Embodiment 1 is that the nitrogen concentration of the modified surface 6 decreases from the outermost surface in the depth direction (in the direction of the interface with the hard carbon film 5). It is in.

FIG. 3 is a schematic view of a film forming apparatus for forming the hard carbon film 5 and the modified surface 6 which compose the ferromagnetic metal thin film type magnetic tape of the second invention by the plasma CVD method. The figure is shown. In the figure, 8 is a vacuum chamber, and the pressure inside the vacuum chamber 8 is 10 ^-4 torr using a vacuum pump 9.
Evacuation is performed so as to obtain a high vacuum state of r to 10 ^-5 torr. Reference numeral 10 denotes a metal thin film type magnetic tape stock having a ferromagnetic metal thin film 3 and a back coat layer 4 formed on a non-magnetic substrate 1, which is fed from a winding roll 11
Book pass rolls 12 and 13 and a cylindrical cooling can 14
It is wound on the winding roll 15 via the outer peripheral surface of. The cooling can 14 has a function of controlling rotation so that the metal thin film magnetic tape stock 10 can be conveyed at a constant speed.

Reference numeral 16 denotes a discharge tube (non-equilibrium plasma generating space) for forming the hard carbon film 5 on the surface of the ferromagnetic metal thin film 3 of the metal thin film type magnetic tape raw sheet 10.
A pipe-shaped discharge electrode 17 is installed inside the unit 6. The pipe-shaped discharge electrode 17 is a power source 18 for plasma generation.
The plasma generating power source 18 is connected to
Method of applying only either DC voltage or AC voltage or method of applying DC voltage and AC voltage in a superimposed manner
Different types of discharge methods can be adopted. Reference numeral 19 is a raw material gas inlet for introducing a mixed gas (raw material gas) of a hydrocarbon type gas and an inorganic type gas such as argon into the discharge tube 16.

Reference numerals 24, 25 and 26 denote discharge tubes (non-equilibrium plasma generating space) for forming the modified surface 6 on the hard carbon film 5. Inside the discharge tubes 24, 25 and 26, punching metal is provided. Discharge electrodes 27, 28 and 29 are installed respectively. Punching metal discharge electrodes 27, 28, 2
Reference numeral 9 is connected to plasma generating power sources 30, 31, and 32, respectively. As the plasma generating power sources 30, 31, 32, a method of applying only a DC voltage or an AC voltage or a DC voltage and an AC voltage are used. It is possible to employ three types of discharge methods, in which the voltages are superimposed and applied. Three
3, 34 and 35 are nitrogen-containing organic gas, hydrocarbon gas,
Discharge tube 2 with mixed gas (raw material gas) consisting of inorganic gas
It is a source gas introduction port for introducing into 4, 25 and 26, respectively.

Example 2-1 Surface roughness analysis by a scanning tunneling microscope (STM) showed a maximum height roughness (R _max ) of 15 nm and a diameter of 200 n.
The micro-projection layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of CoNiO having a film thickness of 180 nm is formed on the surface of each of the polyethylene terephthalate films 1 having a thickness of 10 μm by the continuous incident angle changing vapor deposition method.
Form. After that, a back coat layer 4 is formed to a thickness of 500 nm on the opposite surface of the polyethylene terephthalate film 1 by a wet coating method.

Next, the metal thin film type magnetic tape stock 10 is placed inside the vacuum chamber 8 of the film forming apparatus shown in FIG.
After evacuating the interior, hexane gas (hydrocarbon gas: C ₆ H ₁₄ ) and argon gas (inorganic gas: Ar) were introduced into the discharge tube 16, respectively, and the pressure ratio of hexane gas and argon gas was changed. 4: 1, total gas pressure 0.3 torr
The gas flow rate is adjusted to be r. In addition, the discharge tube 24
N-propylamine gas (nitrogen-containing organic gas: C ₃
H ₉ N), methane gas (hydrocarbon-based gas: CH ₄ ) and hydrogen gas (inorganic-based gas: H ₂ ) are introduced, respectively, and the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas is 2: 7: 1. The gas flow rate is adjusted so that the total gas pressure becomes 0.1 torr. Next, n-propylamine gas, methane gas, and hydrogen gas were introduced into the discharge tube 25, respectively, and the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas was 4.5: 4.5: 1, total gas pressure. Is 0.1t
The gas flow rate is adjusted to be orr. Further, n-propylamine gas, methane gas, and hydrogen gas were introduced into the discharge tube 26, and the pressure ratio of n-propylamine gas, methane gas, and hydrogen gas was 7: 2: 1, and the total gas pressure was 0.1 torr. Adjust the gas flow rate so that
After that, the metal thin film type magnetic tape raw material 10 is 3 to 5 m /
While being conveyed at a traveling speed of min, a non-equilibrium plasma is generated by applying a DC voltage of 1000 V to the pipe-shaped discharge electrode 17, and the non-equilibrium plasma is generated on the surface of the ferromagnetic metal thin film 3 of the metal thin film magnetic tape stock 10. The hard carbon film 5 is formed to a thickness of 13 nm. Further, by applying a DC voltage of 2000 V to the punching metal discharge electrodes 27, 28, 29, non-equilibrium plasma is generated, and the nitrogen concentration on the surface of the hard carbon film 5 of the metal thin film type magnetic tape stock 10 is from the outermost surface. A modified surface 6 having a thickness of 2 nm is formed in the depth direction (toward the interface with the hard carbon film 5).

Next, a fluorine-containing lubricant layer 7 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) is formed on the surface of the modified surface 6 by a wet coating method to a thickness of about 3 nm. , 8 mm width was slit to produce a metal thin film type magnetic tape for VTR of 8 mm.

The Vickers hardness of the hard carbon film 5 obtained in Example 2-1 was 2500 kg / mm ² .

Example 2-2 As a raw material gas for forming the modified surface 6, dimethylformamide (nitrogen-containing organic gas:
8 mm by the same method as in Example 2-1 except that the modified surface 6 is formed to a thickness of 0.5 nm using C ₃ H ₇ NO).
A metal thin film type magnetic tape for VTR was produced.

Example 2-3 Example 2-1 except that the reformed surface 6 having a thickness of 2.5 nm in which the nitrogen concentration decreases from the outermost surface in the depth direction is formed on the surface of the hard carbon film 5. 8mmV by the same method as
A metal thin film type magnetic tape for TR was produced.

Example 2-4 The total gas pressure of the raw material gas for forming the modified surface 6 was set to 0.05 to
A metal thin film magnetic tape for 8 mm VTR was manufactured by the same method as in Example 2-1 except that the modified surface 6 was formed to have a thickness of 1 mm and the modified surface 6 was rr.

Example 2-5 As a raw material gas for forming the modified surface 6, pyridine (nitrogen-containing organic gas: C ₅ H ₅ N) was used instead of n-propylamine, and the total gas pressure was 0.05 torr. In the same manner as in Example 2-1, except that the modified surface 6 was formed to a thickness of 1 mm, a metal thin film magnetic tape for 8 mm VTR was produced.

Comparative Example 2-1 Example 2-Except that the fluorine-containing lubricant layer 7 was directly formed on the surface of the hard carbon film 5 without forming the modified surface 6 having the concentration gradient of nitrogen atoms. 8mm by the same method as 1
A metal thin film type magnetic tape for VTR was produced.

Comparative Example 2-2 As a raw material gas for forming the modified surface 6, instead of a mixed gas of n-propylamine, methane and hydrogen, n-propylamine, methane and oxygen (inorganic gas: O ₂ ). Using a mixed gas of, the pressure ratio is 2: 7: 1, 4.5: 4.5: 1,
A metal thin film magnetic tape for 8 mm VTR was produced by the same method as in Example 2-1 except that the ratio was 1: 7: 2.

Comparative Example 2-3 The same as Example 2-1 except that the modified surface 6 having a thickness of 4 nm in which the nitrogen concentration was decreased from the outermost surface in the depth direction was formed on the surface of the hard carbon film 5. 8mm VTR
A metal thin film type magnetic tape was produced.

Comparative Example 2-4 8 m was prepared in the same manner as in Example 2-1 except that the Vickers hardness of the hard carbon film was 1300 kg / mm ^2.
A metal thin film type magnetic tape for mVTR was produced.

(Above) Examples and Comparative Examples 2-3, 2-4
In the modified surface 6 formed on the surface of the hard carbon film 5, the nitrogen concentration decreases from the outermost surface in the depth direction. Angle-resolved X-ray photoelectron spectroscopy (Angl
It was confirmed by compositional analysis in the depth direction using e Resolved XPS).

The chemical composition (atomic ratio) and the chemical bonding state of the modified surface 6 in Examples and Comparative Examples were determined by X-ray using the metal thin film magnetic tape stock 10 on which the fluorine-containing lubricant layer 7 was not formed. Surface analysis was performed by photoelectron spectroscopy (XPS), and the results are shown in (Table 3).

A hard carbon film having a thickness of 1 to 3 μm is formed on a silicon wafer instead of the metal thin film type magnetic tape stock 10.
Several kinds of samples having a thickness of about m were prepared, and the Vickers hardness of the above samples was measured using a micro hardness meter (micro hardness meter).
The Vickers hardness of the hard carbon film corresponding to m was calculated, and the value was set as the Vickers hardness value of the hard carbon film 5 in the examples and comparative examples. The film thickness of the hard carbon film in the above sample was a value measured by an ellipsometer. The results are shown in (Table 3).

[0078]

[Table 3]

Each 8 obtained in the above examples and comparative examples
The same measurement as in (Example 1) was performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape).

Table 4 shows the evaluation results of the metal thin film magnetic tape for 8 mm VTR produced in each of the examples and comparative examples.

[0081]

[Table 4]

As is clear from (Table 3) and (Table 4),
The metal thin film magnetic tape of this example has a hard modified surface with a thickness of less than 3 nm that contains an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into a lubricant molecule. Since it is formed on the carbon film, the hardness of the protective film consisting of the hard carbon film and the modified surface is not reduced, and the spacing loss between the ferromagnetic metal thin film and the magnetic head is not increased, and the tape surface is not increased. Moreover, the lubricant molecules can be firmly held. Furthermore, since the nitrogen concentration on the modified surface decreases from the outermost surface in the depth direction (toward the interface with the hard carbon film), the internal stress of the modified surface itself is moderate. Can be relaxed to
Moreover, by applying a method of exposing the hard carbon film surface to a glow discharge plasma by a mixed gas of a nitrogen-containing organic gas, a hydrocarbon gas, and an inorganic gas in order to form a modified surface on the hard carbon film, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning the hard carbon film surface, it is possible to further improve the adhesion between the hard carbon film and the modified surface. Therefore, since the synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, running durability and weather resistance can be dramatically improved.

In Comparative Example 2-1, the modified surface was not formed on the hard carbon film, and in Comparative Example 2-2, the atomic ratio of nitrogen to carbon and the atomic ratio of nitrogen to oxygen on the modified surface were not formed. Since the ratio is within the appropriate range of the present invention, the adhesion between the hard carbon film and the fluorine-containing lubricant layer is not improved, resulting in deterioration of running durability and weather resistance. .

In Comparative Example 2-3, due to the chemical affinity between the nitrogen atom contained in the modified surface and the polar group (carboxyl group) introduced into the lubricant molecule, the modified surface was hard as an intermediate layer. Although the carbon film and the lubricant layer adhere firmly, the thickness of the modified surface is too large, so the synergistic effect of the wear resistance of the hard carbon film and the low shearing force of the lubricant layer is fully exerted. However, the running durability was deteriorated.

In Comparative Example 2-4, the running durability was deteriorated because the Vickers hardness of the carbon film was low.

In the above embodiment, the nitrogen concentration of the modified surface 6 gradually decreases from the outermost surface in the depth direction, but the nitrogen concentration continuously decreases. Also has the same effect.

(Third Embodiment) A third embodiment of the present invention and a sixth embodiment of the present invention will now be described in detail with reference to the drawings. The difference between this embodiment and Embodiment 1 is that the modified surface 6 has an island structure as shown in FIG.

Example 3-1 Surface roughness analysis by a scanning tunneling microscope (STM) showed a maximum height roughness (R _max ) of 20 nm and a diameter of 200 n.
The micro-projection layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of CoNiO having a film thickness of 180 nm is formed on the surface of each of the polyethylene terephthalate films 1 having a thickness of 10 μm by the continuous incident angle changing vapor deposition method.
Form. After that, a back coat layer 4 is formed to a thickness of 500 nm on the opposite surface of the polyethylene terephthalate film 1 by a wet coating method.

Next, the metal thin film type magnetic tape stock 10 is placed inside the vacuum chamber 8 of the film forming apparatus shown in FIG.
After evacuation of the inside, toluene gas (hydrocarbon gas: C ₇ H ₈ ) and argon gas (inorganic gas: Ar) are introduced into the discharge tube 16, respectively, and the pressure ratio between the toluene gas and the argon gas is changed. 4: 1, total gas pressure 0.2 torr
Adjust the gas flow rate so that Further, pyridine gas (nitrogen-containing organic gas: C ₅ H ₅ N) and oxygen gas (inorganic gas: O ₂ ) are introduced into the discharge tube 20, respectively, and the pressure ratio of pyridine gas and oxygen gas is 3: 2. , The total gas pressure is 0.
The gas flow rate is adjusted to be 1 torr. After that, the metal thin film type magnetic tape stock 10 is fed at 15 m / min.
While being transported at a traveling speed of 1, the non-equilibrium plasma is generated by applying a DC voltage of 1300 V to the pipe-shaped discharge electrode 17, and the metal thin film magnetic tape raw sheet 1 is produced.
A hard carbon film 5 on the surface of the ferromagnetic metal thin film 3 of 0
nm film is formed. Further, by applying a direct current voltage of 1200 V to the punching metal discharge electrode 21, non-equilibrium plasma is generated, and the island-shaped modified surface 6 is formed to a thickness of 2 nm on the hard carbon film 5 surface of the metal thin film type magnetic tape raw tape 10. Form.

Next, a fluorine-containing lubricant layer 7 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) was formed on the surface of the modified surface 6 by a wet coating method to a thickness of about 3 nm. , 8 mm width was slit to produce a metal thin film type magnetic tape for VTR of 8 mm.

The Vickers hardness of the hard carbon film 5 obtained in Example 3-1 was 2200 kg / mm ² .

Example 3-2 Pyridine and O _{2 were} used as source gases for forming the island-shaped reformed surface 6.
By the same method as in Example 3-1, except that a mixed gas of butylamine (nitrogen-containing organic gas: C ₄ H ₁₁ N) and ammonia (inorganic gas: NH ₃ ) is used instead of the mixed gas of , 8 mm VTR metal thin film type magnetic tape was produced.

Example 3-3 Pyridine and O _{2 were} used as source gases for forming the island-shaped reformed surface 6.
N-propylamine (nitrogen-containing organic gas: C ₃ H ₉ N) and argon (inorganic gas: Ar) instead of the mixed gas with
8 mm by the same method as in Example 3-1 except that the thickness of the island-shaped modified surface 6 is set to 1 nm by using a mixed gas of
A metal thin film type magnetic tape for VTR was produced.

Comparative Example 3-1 The same as Example 3-1 except that the fluorine-containing lubricant layer 7 was formed directly on the surface of the hard carbon protective film 5 without forming the island-shaped modified surface 6. By the method, a metal thin film type magnetic tape for 8 mm VTR was produced.

Comparative Example 3-2 Without forming the hard carbon film 5 on the surface of the ferromagnetic metal thin film 3,
A metal thin film magnetic tape for 8 mm VTR was manufactured by the same method as in Example 3-1 except that the directly modified island surface 6 was formed to a thickness of 10 nm.

Comparative Example 3-3 The same as Example 3-1 except that styrene (hydrocarbon gas: C ₈ H ₈ ) was used instead of pyridine as a raw material gas for forming the island-shaped reformed surface 6. 8mm VTR depending on the method
A metal thin film type magnetic tape was produced.

Comparative Example 3-4 Example 3 was repeated except that the thickness of the island-shaped modified surface 6 was set to 8 nm.
A metal thin film type magnetic tape for 8 mm VTR was produced by the same method as in -1.

Comparative Example 3-5 By the same method as in Example 3-1, except that the fluorine-containing lubricant layer 7 was formed after exposing the surface of the hard carbon film 5 to glow discharge plasma containing only pyridine gas. 8 mmV
A metal thin film type magnetic tape for TR was produced.

Comparative Example 3-6 A method similar to that in Example 3-1 was conducted except that the fluorine-containing lubricant layer 7 was formed after exposing the surface of the hard carbon film 5 to glow discharge plasma containing only O ₂ gas. , 8mm VTR
A metal thin film type magnetic tape was produced.

Comparative Example 3-7 8 m was prepared in the same manner as in Example 3-1, except that the Vickers hardness of the hard carbon film was 1200 kg / mm ^2.
A metal thin film type thin film tape for MVTR was produced.

In the above embodiment, the island-shaped modified surface 6 formed on the surface of the hard carbon film 5 is present more in the vicinity of the convex portion than in the vicinity of the concave portion of the surface of the hard carbon film 5 by the scanning tunneling microscope ( Maximum height roughness (R _max ) of the metal thin film type magnetic tape stock 10 before and after the island-shaped modified surface 6 is formed by STM)
And the two-dimensional analysis (area analysis) using a scanning Auger microprobe (SAM).

The chemical composition (atomic ratio) and the chemical bonding state of the island-shaped modified surface 6 in Examples and Comparative Examples are as follows: Fluorine-containing lubricant layer 7 is not formed.
0 was used for surface analysis by X-ray photoelectron spectroscopy (XPS), and the results are shown in (Table 5).

A hard carbon film having a thickness of 1 to 3 μm is formed on a silicon wafer instead of the metal thin film type magnetic tape stock 10.
Several kinds of samples formed with a thickness of about m were prepared, and the Vickers hardness of the above sample was measured using a micro hardness meter (micro hardness meter).
The Vickers hardness of the hard carbon film corresponding to m was calculated, and the value was set as the Vickers hardness value of the hard carbon film 5 in the examples and comparative examples. The film thickness of the hard carbon film in the above sample was a value measured by an ellipsometer. The results are shown in (Table 5).

[0104]

[Table 5]

Each 8 obtained in the above Examples and Comparative Examples
The following measurements were performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) Still life Using an 8mm VTR modified for still life measurement, 2
A video signal was recorded on each magnetic tape in an environment of 3 ° C.-10% RH, reproduction was performed in the still mode under the condition of a load of 30 g, and the time until the reproduction output dropped by 6 dB was shown. The measurement was terminated after a maximum of 180 minutes. (2) Head clogging Using an 8 mm VTR modified for RF output measurement, 40 ° C
Under an environment of -80% RH, a video signal was recorded on each magnetic tape having a length of 60 minutes, and reproduction was performed 300 passes. The time during which the reproduction output was continuously reduced by 6 dB or more during the durability test by the repeated running was accumulated, and the time was defined as the head clogging time. (3) Weather resistance test As a weather resistance test, the magnetic tape was left in an environment of 40 ° C-90% RH for about 30 days, and the occurrence state of coating unevenness, rust, crystals, peeling, etc. was observed with an optical microscope. A graded evaluation was performed. The evaluation was rated as 5 when there was no problem in practical use, and as 1 when there was a problem in practical use. (4) Stainless steel with a friction coefficient μ _k diameter of 4 mm and a surface roughness of 0.2 S (SUS4
20J2) The magnetic layer forming surface of each magnetic tape is in contact with the cylinder over 90 °.
Entry side tension is 30g, tape running speed is 0.5mm / se
The output side tension Xg when set to c was measured, and the friction coefficient was calculated from the following equation.

[0106]

[Equation 2]

The measurement environment was 25 ° C.-30% RH, and the friction coefficient was determined to be the value measured on the 30th pass.

Table 6 shows the evaluation results of the 8 mm VTR metal thin film magnetic tapes produced in the respective examples and comparative examples.

[0109]

[Table 6]

As is clear from (Table 5) and (Table 6),
The metal thin film type magnetic tape of this example is an island-shaped modified surface having a thickness of less than 3 nm, which contains an appropriate amount of a nitrogen atom having a strong chemical affinity with a polar group (carboxyl group) introduced into a lubricant molecule. Is formed on the hard carbon film, the magnetic head and the metal cylinder of the VTR that rotate at high speed without lowering the hardness of the protective film itself and without increasing the spacing loss between the magnetic layer and the magnetic head. In addition, the lubricant molecules can be firmly held at the tip portion of the tape protrusion that is in actual contact with the guide post or the like. Further, by applying a method of exposing the surface of the hard carbon film to glow discharge plasma by a mixed gas of a nitrogen-containing organic gas and an inorganic gas in order to form an island-shaped modified surface on the hard carbon film, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning the surface, it is possible to secure good adhesion between the hard carbon film and the island-shaped modified surface. Therefore, since the synergistic effect of the hard carbon film and the lubricant layer formed on the magnetic layer can be sufficiently exerted, the still life is remarkably improved, the head clogging is greatly improved, and the weather resistance is greatly improved. We were able to achieve driving stability at the same time.

In Comparative Example 3-1, the island-shaped modified surface was not formed on the hard carbon film, and in Comparative Example 3-3, the island-shaped modified surface was formed on the hard carbon film. Since the raw material gas does not contain the specific element (nitrogen) of the present invention in the molecule, the adhesion between the hard carbon film and the fluorine-containing lubricant layer is not improved, the still life is reduced, and the long time is prolonged. The result is that the head is clogged.

In Comparative Example 3-2, since the hardness of the island-shaped modified surface is lower than that of the hard carbon film, Comparative Example 3-4 is also used.
, The chemical affinity between the nitrogen atoms contained in the island-shaped modified surface and the polar groups (carboxyl groups) introduced into the lubricant molecule makes the island-shaped modified surface an intermediate layer for lubrication with the hard carbon film. Although it firmly adheres to the lubricant layer, the thickness of the island-shaped modified surface is too large, so the synergistic effect of the wear resistance of the hard carbon film and the low shearing force of the lubricant layer is not sufficiently exerted. , The running stability of the tape deteriorated and the still life became shorter.

In Comparative Example 3-5, since only the nitrogen-containing organic gas was used as the raw material gas for forming the island-shaped reformed surface, the hard carbon film surface was not cleaned and chemical species (reaction As a result, it is not possible to secure good adhesion between the hard carbon film and the island-shaped modified surface, resulting in a decrease in still life and occurrence of head clogging for a long time. The result was.

In Comparative Example 3-6, since the surface of the hard carbon film is significantly damaged by the impact of the charged particles generated from O ₂ which is an inorganic gas, the still life is remarkably reduced and the weather resistance is deteriorated. became.

In Comparative Example 3-7, the still life was shortened because the Vickers hardness of the carbon film was low.

The diameter of the island-shaped modified surface in this embodiment is preferably in the range of 1 nm to 100 nm, preferably 10 nm to
A range of 50 nm is desirable.

(Embodiment 4) The fourth embodiment of the present invention and the sixth embodiment of the present invention will be described in detail with reference to the drawings. The difference between this embodiment and Embodiment 1 is that the modified surface 6 is formed on the surface of the hard carbon film having specific properties.

Example 4-1 Surface roughness analysis by a scanning tunneling microscope (STM) showed a maximum height roughness (R _max ) of 15 nm and a diameter of 200 n.
The micro-projection layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of CoNiO having a film thickness of 180 nm is formed on the surface of each of the polyethylene terephthalate films 1 having a thickness of 10 μm by the continuous incident angle changing vapor deposition method.
Form. After that, a back coat layer 4 is formed to a thickness of 500 nm on the opposite surface of the polyethylene terephthalate film 1 by a wet coating method.

Next, the metal thin film type magnetic tape stock 10 is installed inside the vacuum chamber 8 of the film forming apparatus shown in FIG.
After evacuation of the inside, the temperature of the cylindrical cooling can 14 is set to 15 ° C. Next, methane gas (hydrocarbon-based gas: CH ₄ ) and argon gas (inorganic-based gas: Ar) are introduced into the discharge tube 16, respectively, and the pressure ratio of methane gas and argon gas is 4: 1, and the total gas pressure is 0. .25 torr
Adjust the gas flow rate so that Further, pyridine gas (nitrogen-containing organic gas: C ₅ H ₅ N) and hydrogen gas (inorganic gas: H ₂ ) are introduced into the discharge tube 20, respectively, and the pressure ratio of pyridine gas and hydrogen gas is 3: 2. , The total gas pressure is 0.
The gas flow rate is adjusted to be 1 torr. After that, the metal thin film type magnetic tape raw material 10 is applied at 3 to 5 m / mi.
While being conveyed at a traveling speed of n, a DC voltage of 800 V is applied to the pipe-shaped discharge electrode 17 to generate non-equilibrium plasma, and the metal thin film magnetic tape raw sheet 1
A hard carbon film 5 on the surface of the ferromagnetic metal thin film 3 of 0
nm film is formed. Further, by applying a DC voltage of 1000 V to the punching metal discharge electrode 21, non-equilibrium plasma is generated, and the island-shaped modified surface 6 is formed to a thickness of 1 nm on the hard carbon film 5 surface of the metal thin film type magnetic tape raw tape 10. Form.

Then, a fluorine-containing lubricant layer 7 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) was formed on the surface of the modified surface 6 by a wet coating method to a thickness of about 3 nm. , 8 mm width was slit to produce a metal thin film type magnetic tape for VTR of 8 mm.

The Raman spectrum of the hard carbon film 5 obtained in Example 4-1 is shown in FIG. From FIG. 5, the area intensity ratio of the Raman spectrum of the hard carbon film 5 was 0.94.

Further, the hard carbon film 5 obtained in Example 4-1
It was found from the measurement result by Rutherford backscattering analysis (RBS) that the density was 2.3 g / cm ³ .

Further, the hard carbon film 5 obtained in Example 4-1
Had a Vickers hardness of 2800 kg / mm ² .

Example 4-2 The pressure ratio of methane gas, which is the raw material gas for forming the hard carbon film 5, and argon gas was 3: 1, and the total gas pressure was 0.2 to.
A metal thin film magnetic tape for 8 mm VTR was produced by the same method as in Example 4-1 except that rr and the voltage applied to discharge were 1300 V DC.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 4-2 was 0.83, and the density was 2.7.
The g / cm ³ and Vickers hardness were 3200 kg / mm ² .

Example 4-3 The pressure ratio of methane gas, which is a raw material gas for forming the hard carbon film 5, and argon gas was 5: 1, and the total gas pressure was 0.3 to.
rr, Example 4 except that the discharge applied voltage is set to a DC voltage of 700 V, and the pressure ratio of pyridine gas, which is a raw material gas for forming the reforming surface 6, and hydrogen gas is set to 1: 3.
A metal thin film type magnetic tape for 8 mm VTR was produced by the same method as in 1.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 4-3 was 2.91 and the density was 1.5.
The g / cm ³ and Vickers hardness were 2000 kg / mm ² .

Example 4-4 The pressure ratio of methane gas as a raw material gas for forming the hard carbon film 5 to argon gas was 5: 1, and the total gas pressure was 0.3 to.
rr, the voltage applied to discharge is set to 700 V, and allylamine (nitrogen-containing organic gas: C ₃ H ₇ N) is used instead of pyridine as a raw material gas for forming the reformed surface 6, and hydrogen is used instead of hydrogen. Ammonia (inorganic gas: NH ₃ )
Was used to prepare a metal thin film magnetic tape for 8 mm VTR by the same method as in Example 4-1 except that the pressure ratio of pyridine gas and ammonia gas was 1: 3.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 4-4 was 2.91, and the density was 1.5.
The g / cm ³ and Vickers hardness were 2000 kg / mm ² .

Comparative Examples 4-1 to 4-3 In order to clarify the effect of this example, the pressure ratio of methane gas and argon gas, the total gas pressure, the temperature of the cylindrical cooling can 14, and the discharge applied voltage were set. Changed, other than Example 4-1
By the same method as, the area intensity ratio of Raman spectrum,
Three types of metal thin film magnetic tapes for 8 mm VTR having hard carbon films 5 having different densities and Vickers hardness were formed. Particularly in Comparative Example 4-3, benzene (hydrocarbon-based gas: C ₆ H ₆ ) was used in place of pyridine which is a raw material gas for forming the reformed surface 6, and the same method as in Example 4-1 except for the above. Thus, the modified surface 6 was formed.

The area intensity ratio, the density and the Vickers hardness of the Raman spectrum of the hard carbon film 5 obtained in Comparative Examples 4-1 to 4-3 are shown in (Table 7).

[0132]

[Table 7]

Comparative Example 4-4 As Example 4-1 except that tetramethyltin (tin-containing organic gas: C ₄ H ₁₂ Sn) was used instead of pyridine as a raw material gas for forming the modified surface 6. 8m by the same method
A metal thin film type magnetic tape for mVTR was produced.

The chemical composition (atomic ratio) and the chemical bonding state of the modified surface 6 in Examples and Comparative Examples were determined by X-ray measurement using the metal thin film magnetic tape stock 10 on which the fluorine-containing lubricant layer 7 was not formed. The surface was analyzed by photoelectron spectroscopy (XPS), and the results are shown in (Table 7).

In place of the metal thin film type magnetic tape raw material 10, a hard carbon film having a thickness of 1 to 3 μm is formed on a silicon wafer.
Several kinds of samples formed with a thickness of about m were prepared, and the Vickers hardness of the above sample was measured using a micro hardness meter (micro hardness meter).
The Vickers hardness of the hard carbon film corresponding to m was calculated, and the value was set as the Vickers hardness value of the hard carbon film 5 in the examples and comparative examples. The film thickness of the hard carbon film in the above sample was a value measured by an ellipsometer.

Each 8 obtained in the above Examples and Comparative Examples
The following measurements were performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) Still life Using an 8mm VTR modified for still life measurement, 2
A video signal was recorded on each magnetic tape in an environment of 3 ° C.-10% RH, reproduction was performed in the still mode under the condition of a load of 30 g, and the time until the reproduction output dropped by 6 dB was shown. The measurement was terminated after a maximum of 180 minutes. (2) Output reduction 23 ° C using an 8 mm VTR modified for RF output measurement
Under an environment of -10% RH, a video signal was recorded on each magnetic tape having a length of 60 minutes, and reproduction was performed 100 passes. As the definition of output reduction, the output of the first pass of reproduction was used as a reference (0 dB), and the value (minimum output value) at which the reproduction output was most decreased during the durability test by the repeated running was displayed in decibels. (3) Weather resistance test As a weather resistance test, the magnetic tape was left in an environment of 60 ° C-90% RH for about 10 days, and the occurrence state of coating unevenness, rust, crystals, peeling, etc. was observed with an optical microscope. A graded evaluation was performed. The evaluation was rated as 5 when there was no problem in practical use, and as 1 when there was a problem in practical use. (4) Stainless steel with a friction coefficient μ _k diameter of 4 mm and a surface roughness of 0.2 S (SUS4
20J2) The magnetic layer forming surface of each magnetic tape is in contact with the cylinder over 90 °.
Entry side tension is 30g, tape running speed is 0.5mm / se
The output side tension Xg when set to c was measured, and the friction coefficient was calculated from the following equation.

[0137]

[Equation 3]

The measurement environment was 25 ° C.-30% RH, and the friction coefficient was set to the value measured on the 30th pass.

Table 8 shows the evaluation results of the 8 mm VTR metal thin film magnetic tapes produced in the respective examples and comparative examples.

[0140]

[Table 8]

As is clear from (Table 7) and (Table 8),
In the metal thin film magnetic tape of this example, the modified surface having a thickness of less than 3 nm containing an appropriate amount of a nitrogen atom having a strong chemical affinity with the polar group (carboxyl group) introduced into the lubricant molecule is SP. ^Since it is formed on a hard carbon film that has a high hardness and a dense structure mainly composed of ³ bonds, it does not reduce the hardness of the protective film consisting of the hard carbon film and the modified surface, and is a ferromagnetic metal. Lubricant molecules can be firmly held on the tape surface without increasing the spacing loss between the thin film and the magnetic head. Further, in order to form a modified surface on the hard carbon film, by applying a method of exposing the hard carbon film surface to glow discharge plasma with a mixed gas of a nitrogen-containing organic gas and an inorganic gas, Since the chemically active species (reactive species) in the plasma can be deposited while cleaning, good adhesion between the hard carbon film and the modified surface can be ensured. Therefore, the synergistic effect of the hard carbon film formed on the magnetic layer and the lubricant layer can be sufficiently exerted, and the durability and weather resistance can be dramatically improved.

In Comparative Example 4-1, since the area intensity ratio of the Raman spectrum of the hard carbon film is large (the proportion of SP ³ bonds is small), the Vickers hardness is low, and the density is low, the durability and the weather resistance are low. However, the driving stability was deteriorated.

In Comparative Example 4-2, the area intensity ratio of the Raman spectrum of the hard carbon film was extremely small (because the proportion of SP ³ bonds was very large), so that the head sliding surface of the head sliding surface during the repeated running test was examined. The output reduction due to uneven wear between dissimilar materials increased.

In Comparative Example 4-3, the area intensity ratio of the Raman spectrum of the hard carbon film is large (the ratio of SP ³ bonds is small), the Vickers hardness is low, and the modified surface is formed on the hard carbon film. Since the raw material gas for containing does not contain the specific element (nitrogen atom) of the present invention in the molecule, since the adhesion between the hard carbon film and the fluorine-containing lubricant layer is not improved, durability, Weather resistance and running stability deteriorated.

In Comparative Example 4-4, tin contained in the modified surface 6 causes metal adhesion to the head sliding surface in a low humidity environment, resulting in a significant decrease in still life and a significant deterioration in output reduction. Became. Furthermore, there was a problem of poor weather resistance such as rusting on the surface of the metal thin film type magnetic tape.

Although the nitrogen concentration distribution in the modified surface 6 of this example was constant, the nitrogen concentration was changed from the outermost surface to the depth direction (the interface with the hard carbon film 5 as in Example 2). The same effect can be obtained even in the case of a structure in which the modified surface 6 has a decreasing structure (in the direction of 1) or in the case where the modified surface 6 has an island structure as in the third embodiment.

(Embodiment 5) A fifth embodiment of the present invention will be described in detail below with reference to the drawings. The difference between this embodiment and Embodiment 4 is that the modified surface 6 is not formed as shown in FIG.

Example 5-1 Surface roughness analysis by a scanning tunneling microscope (STM) showed a maximum height roughness (R _max ) of 15 nm and a diameter of 200 n.
The micro-projection layer 2 of about m is 10 ⁵ to 10 ⁹ per 1 mm ^2.
A ferromagnetic metal thin film 3 made of CoNiO having a film thickness of 180 nm is formed on the surface of each of the polyethylene terephthalate films 1 having a thickness of 10 μm by the continuous incident angle changing vapor deposition method.
Form. After that, a back coat layer 4 is formed to a thickness of 500 nm on the opposite surface of the polyethylene terephthalate film 1 by a wet coating method.

Next, the metal thin film type magnetic tape stock 10 is installed inside the vacuum chamber 8 of the film forming apparatus shown in FIG.
After evacuation of the inside, the temperature of the cylindrical cooling can 14 is set to 15 ° C. Next, methane gas (hydrocarbon-based gas: CH ₄ ) and argon gas (inorganic-based gas: Ar) are introduced into the discharge tube 16, respectively, and the pressure ratio of methane gas and argon gas is 4: 1, and the total gas pressure is 0. .25 torr
Adjust the gas flow rate so that After that, the metal thin film type magnetic tape raw material 10 is conveyed at a traveling speed of 3 to 5 m / min, and a DC voltage of 800 V is applied to the pipe-shaped discharge electrode 17 to generate non-equilibrium plasma, thereby generating a metal thin film. A hard carbon film 5 having a thickness of 10 nm is formed on the surface of the ferromagnetic metal thin film 3 of the master tape 10 for magnetic tape.

Next, a fluorine-containing lubricant layer 7 made of fluorine-containing carboxylic acid (C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH) was formed on the surface of the hard carbon film 5 by a wet coating method to a thickness of about 3 nm. , 8 mm width was slit to produce a metal thin film type magnetic tape for VTR of 8 mm.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 5-1 was 0.94.

The hard carbon film 5 obtained in Example 5-1
It was found from the measurement result by Rutherford backscattering analysis (RBS) that the density was 2.3 g / cm ³ .

The hard carbon film 5 obtained in Example 5-1
Had a Vickers hardness of 2800 kg / mm ² .

Example 5-2 The pressure ratio of methane gas, which is a raw material gas for forming the hard carbon film 5, and argon gas was 3: 1, and the total gas pressure was 0.2 to.
A metal thin film magnetic tape for 8 mm VTR was produced by the same method as in Example 5-1 except that rr and the voltage applied to discharge were 1300 V DC.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 5-2 was 0.83 and the density was 2.7.
The g / cm ³ and Vickers hardness were 3200 kg / mm ² .

Example 5-3 The pressure ratio of methane gas, which is a raw material gas for forming the hard carbon film 5, and argon gas was 4: 1, and the total gas pressure was 0.3 to.
A metal thin film magnetic tape for 8 mm VTR was produced by the same method as in Example 5-1 except that rr and the voltage applied to discharge were DC voltage of 700V.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 5-3 was 1.24, and the density was 2.1.
The g / cm ³ and Vickers hardness were 2500 kg / mm ² .

Example 5-4 The pressure ratio of methane gas, which is the raw material gas for forming the hard carbon film 5, and argon gas was 5: 1, and the total gas pressure was 0.3 to.
A metal thin-film magnetic tape for 8 mm VTR was manufactured by the same method as in Example 5-1 except that rr and the voltage applied to discharge were DC voltage 550V.

The area intensity ratio of the Raman spectrum of the hard carbon film 5 obtained in Example 5-4 was 2.93, and the density was 1.6.
The g / cm ³ and Vickers hardness were 2000 kg / mm ² .

Comparative Examples 5-1 to 5-4 In order to clarify the effect of this example, the pressure ratio of methane gas and argon gas, the total gas pressure, the temperature of the cylindrical cooling can 14, and the discharge applied voltage were set. Example 5-1 with other changes
By the same method as, the area intensity ratio of Raman spectrum,
Four kinds of 8 mm metal thin film magnetic tapes for VTRs having hard carbon films 5 having different densities and Vickers hardness were formed.

The Raman spectrum area intensity ratio, density and Vickers hardness of the hard carbon films 5 obtained in Comparative Examples 5-1 to 5-4 are shown in (Table 9).

[0162]

[Table 9]

Instead of the metal thin film type magnetic tape stock 10, several kinds of samples were prepared by forming a hard carbon film on a silicon wafer to a thickness of about 1 to 3 μm and using a micro hardness meter (micro hardness meter). The Vickers hardness of the above sample was measured, and the Vickers hardness of the hard carbon film corresponding to a film thickness of 10 nm was calculated by extrapolation from the film thickness dependence, and the value was calculated as the Vickers hardness of the hard carbon film 5 in Examples and Comparative Examples. The hardness value was used. The film thickness of the hard carbon film in the above sample was a value measured by an ellipsometer.

Each 8 obtained in the above Examples and Comparative Examples
The following measurements were performed on a metal thin film magnetic tape for mmVTR (hereinafter, simply referred to as a magnetic tape). (1) Still life Using an 8mm VTR modified for still life measurement, 2
A video signal was recorded on each magnetic tape in an environment of 3 ° C.-10% RH, reproduction was performed in the still mode under the condition of a load of 30 g, and the time until the reproduction output dropped by 6 dB was shown. The measurement was terminated after a maximum of 180 minutes. (2) Output reduction 23 ° C using an 8 mm VTR modified for RF output measurement
Under an environment of -10% RH, a video signal was recorded on each magnetic tape having a length of 60 minutes, and reproduction was performed 100 passes. As the definition of output reduction, the output of the first pass of reproduction was used as a reference (0 dB), and the value (minimum output value) at which the reproduction output was most decreased during the durability test by the repeated running was displayed in decibels.

Table 9 shows the evaluation results of the 8 mm VTR metal thin film magnetic tapes produced in the respective examples and comparative examples.

As is clear from (Table 9), in the metal thin film magnetic tape of this embodiment, the hard carbon film formed on the ferromagnetic metal thin film has a high hardness mainly composed of SP ³ bonds and is dense. Since it is a continuous film having a structure, it is possible to improve durability.

In Comparative Example 5-1 and Comparative Example 5-3, the area intensity ratio of the Raman spectrum of the hard carbon film was large (SP
^Since the proportion of ³ bonds is small) and the Vickers hardness is low, the durability deteriorated.

In Comparative Example 5-2, since the hard carbon film had a low density, the wear resistance was low and the durability was deteriorated.

In Comparative Example 5-4, since the area intensity ratio of the Raman spectrum of the hard carbon film is extremely small (because the ratio of the SP ³ bonds is very large), the head sliding surface of the head sliding surface during the repeated running test was examined. The output reduction due to uneven wear between dissimilar materials increased.

In the above embodiments, only the 8 mm VTR metal thin film type magnetic tape was explained, but the present invention is not limited to this, and other ferromagnetic metal thin film type magnetic tapes, magnetic recording media such as magnetic disks, etc. The same applies.

Further, in the above embodiment, as the raw material gas for generating the glow discharge plasma (that is, the raw material gas for forming the reformed surface) for irradiating the surface of the hard carbon film, the nitrogen-containing organic gas is pyridine, allylamine, n. Although -propylamine, dimethylformamide, and butylamine are used only, the present invention is not limited to these, and the same applies to any organic monomer gas containing a nitrogen atom in its molecule. For inorganic gases,
Although only the case of using H ₂ , Ar, NH ₃ , and O ₂ is shown, the present invention is not limited to these, and He and N ₂ other than the above gases can be similarly applied. Also, only the case where methane gas is used as one of the raw material gases for forming the reformed surface having the concentration gradient of nitrogen atoms is shown, but the same applies to other hydrocarbon-based gases.

In the above embodiment, the modified surface is treated with plasma C
Although only the method of applying only the DC voltage is shown as the discharge method when forming by the VD method, it is not limited to this method, and the method of applying the DC voltage and the AC voltage in a superimposed manner and only the AC voltage The method of applying a voltage can be similarly implemented.

Further, although the hard carbon film is formed by the plasma CVD method in the above embodiment, the present invention is not limited to this manufacturing method, and an ion beam evaporation method, an ion beam sputtering method, a laser evaporation method or the like may be used. It can be similarly implemented.

Further, in the above embodiment, only the method of applying only the DC voltage is shown as the discharge method when the hard carbon film is formed by the plasma CVD method, but the invention is not limited to this method and the DC voltage The method of superimposing and applying the AC voltage and the method of applying only the AC voltage can be similarly implemented.

Further, in the above-mentioned examples, only the fluorine-containing lubricant in which a carboxyl group is introduced into the molecule as a polar group is shown, but -OH, -SH, -NH ₂ , = NH, -NH.
_{NCO, -CONH 2, -CONHR, -CONR} 2, -
COOR, = PR, = PRO, = PRS, -OPO (O
H) ₂ , —OPO (OR) ₂ , —SO ₃ M (wherein R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal), and at least one polarity is selected. Any fluorine-containing lubricant having a group can be similarly applied.

Further, in the above-mentioned embodiments, only the case where the fluorine-containing lubricant layer is formed by the wet coating method has been shown, but the organic vapor deposition method can be similarly used.

[0177]

As described above, according to the present invention, a ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and carbon, nitrogen, A structure in which a modified surface containing oxygen and having an atomic ratio of nitrogen to carbon of 0.8% or more and a thickness of less than 3 nm is formed, and a lubricant layer is further formed on the modified surface, or on a non-magnetic substrate A ferromagnetic metal thin film is formed on the ferromagnetic metal thin film, a hard carbon film is formed on the ferromagnetic metal thin film, and carbon, nitrogen, and oxygen are contained on the hard carbon film, and the atomic ratio of nitrogen to carbon is 0.8% or more. A non-magnetic substrate having a structure in which a nitrogen concentration decreases from the outermost surface in the depth direction to form a modified surface having a thickness of less than 3 nm, and a lubricant layer is further formed on the modified surface. A ferromagnetic metal thin film is formed on top of this, and projections are formed on this ferromagnetic metal thin film. A hard carbon film having a corresponding uneven surface is formed, and carbon, nitrogen, and oxygen are contained on the hard carbon film, and the atomic ratio of nitrogen to carbon is 0.8% or more and the island-like modification with a thickness of less than 3 nm. Surface is formed, and then a lubricant layer is formed on the island-shaped modified surface, or a ferromagnetic metal thin film is formed on a non-magnetic substrate, and a Raman spectrum of about 1380 cm ^-1 is formed on this ferromagnetic metal thin film. The peak existing at 1550 cm ^{-1 is} defined as (A).
The area of (A) when fitting the Gaussian curve to the peaks of (A) and (B) is divided by the area of (B) (area intensity of Raman spectrum). Ratio) is 0.8 to 3.0 and the density is 1.5 g / cm ^3.
A hard carbon film as described above is formed, and a modified surface having a thickness of less than 3 nm, which contains carbon, nitrogen, and oxygen and has an atomic ratio of nitrogen to carbon of 0.8% or more, is formed on the hard carbon film.
Further, a lubricant layer is formed on the modified surface, or a ferromagnetic metal thin film is formed on a non-magnetic substrate, and a peak existing near 1380 cm ^-1 of Raman spectrum is formed on the ferromagnetic metal thin film. (A), the peak existing near 1550 cm ^-1 is (B), and the area of (A) when fitting the Gaussian curve to the peaks of (A) and (B) is ( The value (area intensity ratio of Raman spectrum) divided by the area of B) is 0.8 to 3.0, the density is 1.5 g / cm ³ or more, and the Vickers hardness is 200.
By forming a hard carbon film of 0 kg / mm ² or more and further forming a lubricant layer on the hard carbon film, a magnetic recording medium excellent in electromagnetic conversion characteristics, running stability, durability and weather resistance can be obtained. It is possible to provide it, and its practical value is great.

[Brief description of drawings]

FIG. 1 is a first example, a second example, and a fourth example of the present invention.
Enlarged sectional view showing the structure of the ferromagnetic metal thin film type magnetic tape

FIG. 2 is a schematic view of a film forming apparatus for forming a hard carbon film and a modified surface or an island-shaped modified surface forming the ferromagnetic metal thin film type magnetic tape of the present invention by using a plasma CVD method.

FIG. 3 is a schematic view of a film forming apparatus for forming a hard carbon film and a modified surface having a concentration gradient of nitrogen atoms, which constitute the ferromagnetic metal thin film type magnetic tape of the present invention, by using a plasma CVD method.

FIG. 4 is an enlarged cross-sectional view showing the structure of a ferromagnetic metal thin film type magnetic tape of Example 3 of the present invention.

FIG. 5 is a diagram showing a Raman spectrum of the hard carbon film of Example 4-1 according to the present invention.

FIG. 6 is an enlarged cross-sectional view showing the structure of a ferromagnetic metal thin film magnetic tape of Example 5 of the present invention.

[Explanation of symbols]

 1 Non-Magnetic Substrate 2 Micro Protrusion Layer 3 Ferromagnetic Metal Thin Film 4 Backcoat Layer 5 Hard Carbon Film 6 Modified Surface (or Island Modified Surface) 7 Fluorine-Containing Lubricant Layer 8 Vacuum Tank 9 Vacuum Pump 10 Metal Thin Film Type Raw tape for magnetic tape 11 Unwinding roll 12 Pass roll 13 Pass roll 14 Cooling can 15 Winding roll 16 Discharge tube 17 Discharge electrode 17 Pipe-shaped discharge electrode 18 Plasma generation power source 19 Raw material gas inlet port 20 Discharge tube 21 Punching metal discharge electrode 22 Plasma generation Power supply 23 Raw material gas inlet 24 Discharge tube 25 Discharge tube 26 Discharge tube 27 Punching metal discharge electrode 28 Punching metal discharge electrode 29 Punching metal discharge electrode 30 Plasma generation power supply 31 Plasma generation power supply 32 Plasma generation power supply 33 Raw material gas introduction Mouth 34 Raw material gas inlet 35 Raw material Be introduced ports

Front Page Continuation (72) Inventor Kiyoji Takahashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Person Mikio Murai, 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (27)

[Claims] 1. A ferromagnetic metal thin film is formed on a non-magnetic substrate,
A hard carbon film is formed on the ferromagnetic metal thin film, and the hard carbon film contains carbon, nitrogen, and oxygen, and the atomic ratio of nitrogen to carbon is 0.8% or more and the modified surface having a thickness of less than 3 nm. And a lubricant layer formed on the modified surface. 2. The atomic ratio of nitrogen to oxygen on the modified surface is 1.
The magnetic recording medium according to claim 1, wherein the content is 0% or more. 3. The total sum of nitrogen atoms, oxygen atoms and carbon atoms involved in the C—N bond and the C—O bond on the modified surface is 3.0 at.
% Or more, and the sum total of nitrogen atoms and oxygen atoms involved in the N—O bond is 1.0 at% or less, and the magnetic recording medium according to claim 1 or 2. 4. The magnetic recording medium according to claim 1, 2 or 3, wherein the nitrogen concentration of the modified surface decreases from the outermost surface in the depth direction. 5. The hard carbon film has a Vickers hardness of 2000 k.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a g / mm ² or more. 6. The lubricant layer is --COOH, --OH, --S.
_{H, -NH 2,> NH,} -CONH 2, -CONHR, -
CONR ₂ , -COOR,>PR,>PRO,> PR
_{S, -OPO (OH) 2,} -OPO (OR) 2, -SO 3
A fluorine-containing lubricant layer having at least one polar group selected from M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal). The magnetic recording medium according to claim 1, wherein the magnetic recording medium is a magnetic recording medium. 7. A ferromagnetic metal thin film is formed on a non-magnetic substrate having protrusions, a hard carbon film having an uneven surface corresponding to the protrusions is formed on the ferromagnetic metal thin film, and the hard carbon film is formed on the hard carbon film. An island-shaped reformed surface containing carbon, nitrogen and oxygen and having an atomic ratio of nitrogen to carbon of 0.8% or more and a thickness of less than 3 nm is formed, and a lubricant layer is further formed on the island-shaped reformed surface. A magnetic recording medium having the above structure. 8. The magnetic recording medium according to claim 7, wherein the atomic ratio of nitrogen to oxygen on the island-shaped modified surface is 10% or more. 9. The total sum of nitrogen atoms, oxygen atoms and carbon atoms involved in the C—N bond and the C—O bond of the island-shaped modified surface is 3.
9. The magnetic recording medium according to claim 7, wherein the content is 0 at% or more, and the total sum of nitrogen atoms and oxygen atoms involved in the N—O bond is 1.0 at% or less. 10. The island-shaped modified surface is present more in the vicinity of the convex portion than in the vicinity of the concave portion on the hard carbon film.
The magnetic recording medium according to any one of 1. 11. A hard carbon film having a Vickers hardness of 2000.
It is more than kg / mm < ² >, Claims 7 to 1 characterized by the above-mentioned.
0. The magnetic recording medium according to 0. 12. The lubricant layer is --COOH, --OH, --S.
_{H, -NH 2,> NH,} -CONH 2, -CONHR, -
CONR ₂ , -COOR,>PR,>PRO,> PR
_{S, -OPO (OH) 2,} -OPO (OR) 2, -SO 3
A fluorine-containing lubricant layer having at least one polar group selected from M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal). The magnetic recording medium according to claim 7, wherein the magnetic recording medium is a magnetic recording medium. 13. A ferromagnetic metal thin film is formed on a non-magnetic substrate, and a Raman spectrum of 138 is formed on the ferromagnetic metal thin film.
The peak existing near 0 cm ^{-1 is} defined as (A), and 1550
The peak existing in the vicinity of cm ^{-1 is} defined as (B), and the above (A)
And a value (Raman spectrum area intensity ratio) obtained by dividing the area of (A) by the area of (B) when fitting the peak of (B) with a Gaussian curve is 0.8 to 3.0. A hard carbon film having a density of 1.5 g / cm ³ or more, containing carbon, nitrogen, and oxygen on the hard carbon film, and having an atomic ratio of nitrogen to carbon of 0.8% or more. Three
A magnetic recording medium, characterized in that a modified surface of less than nm is formed, and a lubricant layer is further formed on the modified surface. 14. The magnetic recording medium according to claim 13, wherein the atomic ratio of nitrogen to oxygen on the modified surface is 10% or more. 15. The sum of nitrogen atoms, oxygen atoms and carbon atoms involved in the C—N bond and the C—O bond of the modified surface is 3.0.
15. The magnetic recording medium according to claim 13, wherein the total content of nitrogen atoms and oxygen atoms involved in the N—O bond is 1.0 at% or less, at least at%. 16. The magnetic recording medium according to claim 13, 14 or 15, wherein the nitrogen concentration of the modified surface decreases from the outermost surface in the depth direction. 17. The Vickers hardness of the hard carbon film is 2000.
It is more than kg / mm < ² >, It is characterized by the above-mentioned.
16. The magnetic recording medium according to any one of 16. 18. The lubricant layer is --COOH, --OH, --S.
_{H, -NH 2,> NH,} -CONH 2, -CONHR, -
CONR ₂ , -COOR,>PR,>PRO,> PR
_{S, -OPO (OH) 2,} -OPO (OR) 2, -SO 3
A fluorine-containing lubricant layer having at least one polar group selected from M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal). The magnetic recording medium according to any one of claims 13 to 16, which is characterized in that. 19. A ferromagnetic metal thin film is formed on a non-magnetic substrate, and a Raman spectrum of 138 is formed on the ferromagnetic metal thin film.
The peak existing near 0 cm ^{-1 is} defined as (A), and 1550
The peak existing in the vicinity of cm ^{-1 is} defined as (B), and the above (A)
And a value (Raman spectrum area intensity ratio) obtained by dividing the area of (A) by the area of (B) when fitting the peak of (B) with a Gaussian curve is 0.8 to 3.0. A hard carbon film having a density of 1.5 g / cm ³ or more and a Vickers hardness of 2000 kg / mm ² or more, and a lubricant layer formed on the hard carbon film. And a magnetic recording medium. 20. The lubricant layer is --COOH, --OH, --S.
_{H, -NH 2,> NH,} -CONH 2, -CONHR, -
CONR ₂ , -COOR,>PR,>PRO,> PR
_{S, -OPO (OH) 2,} -OPO (OR) 2, -SO 3
A fluorine-containing lubricant layer having at least one polar group selected from M (where R is a hydrocarbon group having 1 to 22 carbon atoms, M is hydrogen, an alkali metal or an alkaline earth metal). The magnetic recording medium according to claim 19, wherein the magnetic recording medium is a magnetic recording medium. 21. A ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and the surface of the hard carbon film is formed of a nitrogen-containing organic gas and an inorganic gas. A method of manufacturing a magnetic recording medium, comprising forming a modified layer by exposing it to glow discharge plasma with a mixed gas, and then forming a lubricant layer. 22. The method of manufacturing a magnetic recording medium according to claim 21, wherein at least one inorganic gas selected from Ar, He, H ₂ , N ₂ , O ₂ and NH ₃ is used. 23. The magnetic recording medium according to claim 21, wherein the partial pressure of the nitrogen-containing organic gas at the time of forming the modified surface is 20 to 90% of the total gas pressure. Manufacturing method. 24. A ferromagnetic metal thin film is formed on a non-magnetic substrate, a hard carbon film is formed on the ferromagnetic metal thin film, and the surface of the hard carbon film is covered with a nitrogen-containing organic gas and a hydrocarbon gas. A method of manufacturing a magnetic recording medium, which comprises forming a modified layer by exposing to a glow discharge plasma of a mixed gas with an inorganic gas, and then forming a lubricant layer. 25. A modified surface is formed by sequentially exposing the surface of the hard carbon film to glow discharge plasma by a mixed gas in which the ratio of the nitrogen-containing organic gas to the hydrocarbon gas is increased stepwise. 25. The method of manufacturing a magnetic recording medium according to claim 24. 26. The magnetic material according to claim 24, wherein at least one inorganic gas selected from Ar, He, H ₂ , N ₂ , O ₂ , and NH ₃ is used. Recording medium manufacturing method. 27. The magnet according to claim 24, 25 or 26, wherein the partial pressure of the nitrogen-containing organic gas at the time of forming the reformed surface is 20 to 90% of the total gas pressure. Recording medium manufacturing method.