JPH0758544B2 - Magnetic recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having a ferromagnetic metal layer containing cobalt as a main component on a non-magnetic substrate. .

[Conventional technology]

A magnetic recording medium in which a ferromagnetic metal layer such as cobalt or a cobalt alloy is formed on a non-magnetic substrate such as a plastic film has excellent high density recording characteristics. On the other hand, however, the metal is exposed on the surface, so that the corrosion resistance is inferior, so that the magnetic properties are deteriorated, and the growth of corrosion products causes defective running of the magnetic recording medium.

Conventionally, it has been proposed to provide a protective layer made of various lubricants in order to improve runnability, but generally, a magnetic tape having a protective layer made of a lubricant directly on a ferromagnetic metal layer is used as a cassette. If a practical test is carried out under the condition of 40 ° C and 80% RH in the assembled condition, a running failure will occur after a few hours. As a result of investigating the cause, the coefficient of friction increases,
It was found that the larger one had a friction coefficient of 1.0 or more, the effect of the lubricant disappeared, and the friction coefficient increased with time.

Further, conventionally, in order to improve wear resistance and corrosion resistance of a magnetic recording medium, a method of heating the surface of a ferromagnetic metal layer to form Co ₃ O ₄ , Co ₂ O ₃ and CoO (Japanese Patent Publication No. 49-29445). ), The ferromagnetic metal layer is treated in an atmosphere of suitable temperature and humidity to form Co ₃ O.
₄ is formed on the surface (Japanese Examined Patent Publication No. Sho 42-20025), and further, steam of 100 ° C. or higher is sprayed on the surface of the ferromagnetic metal layer to form crystalline CoO (OH) on the surface (Patent Document 1) JP-A-57-123533) has been proposed.

[Problems to be solved by the invention]

However, these methods cannot improve the wear resistance of the magnetic recording medium, and cannot prevent the friction coefficient from increasing with time due to corrosion products. In the method for further generating a Co ₃ O ₄ by heat-treating ferromagnetic metal layer in an atmosphere of proper temperature and humidity as described above, Co ₃ of crystalline
It has a drawback that O ₄ is generated up to the deep part of the ferromagnetic metal layer and causes deterioration of magnetic characteristics.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a magnetic recording medium having excellent corrosion resistance and abrasion resistance.

[Means for solving problems]

In order to achieve the above-mentioned object, the first invention is a magnetic recording medium in which a ferromagnetic metal layer containing cobalt as a main component, for example, a cobalt-nickel alloy, is formed on a non-magnetic substrate by oblique vapor deposition. Coupling energy of Co _{2 P} spectrum in X-ray photoelectron spectroscopy of the surface layer of magnetic metal layer 780.0 ^{± 0.3} eV (2P3 /
2) and 795.6 ^{± 0.3} eV (2P1 / 2) both peaks of 780.0 ^{± 0.3} eV when the back ground is drawn with a straight line so as to contact the spectrum through the rising points on the low binding energy side. The peak height of 785.9 ^{± 0.3} eV is 100 or less, and the binding energy of its O _1S spectrum is 530.5 ^{± 2.5} eV.
When the background is drawn with a straight line so as to come into contact with the spectrum through the rising points on the low binding energy side and the rising point on the high binding energy side of the complex peak in Fig. 3, the peaks on the low binding energy side and the high binding energy side of this complex peak The ratio of the height of the side peaks is regulated in the range of 100 to 110 to 50, and the surface layer of the ferromagnetic metal layer is amorphous containing a hydroxyl group.

In order to achieve the above-mentioned object, a second aspect of the present invention provides a magnetic recording medium in which a ferromagnetic metal layer containing cobalt as a main component, such as a cobalt-nickel alloy, is formed on a non-magnetic substrate by oblique vapor deposition. Coupling energy of Co _{2 P} spectrum in X-ray photoelectron spectroscopy of the surface layer of ferromagnetic metal layer 780.0 ^{± 0.3} eV (2P3 /
2) and 795.6 ^{± 0.3} eV (2P1 / 2) both peaks of 780.0 ^{± 0.3} eV when the back ground is drawn with a straight line so as to contact the spectrum through the rising points on the low binding energy side. The peak height of 785.9 ^{± 0.3} eV is 100 or less, and the binding energy of its O _1S spectrum is 530.5 ^{± 2.5} eV.
When the background is drawn with a straight line so as to come into contact with the spectrum through the rising points on the low binding energy side and the rising point on the high binding energy side of the complex peak in Fig. 3, the peaks on the low binding energy side and the high binding energy side of this complex peak The side peak height ratio is regulated in the range of 100 to 110 to 50, and the surface layer of the ferromagnetic metal layer is amorphous containing hydroxyl groups. It is characterized in that a lubricant layer made of a fluorinated organic compound or a fluorinated organic compound is provided.

〔Example〕

In the present invention, the non-magnetic substrate is, for example, a plastic sheet of polyethylene terephthalate resin, polyimide resin, polyester resin or the like, a substrate of a composite material in which an inorganic substance such as carbon fiber or copper is mixed in the plastic substrate, or aluminum or the like. A non-magnetic metal plate, glass, or the like is used.

In the present invention, examples of the ferromagnetic metal containing cobalt as a main component include, for example, cobalt alone, or cobalt such as cobalt-nickel alloy, cobalt-chromium alloy, cobalt-iron alloy, cobalt-phosphorus alloy, and cobalt-nickel-phosphorus alloy. Alloys are used. In the case of the cobalt-nickel alloy and the cobalt-nickel-phosphorus alloy, the nickel content is preferably about 40% by weight or less.
In the case of cobalt-chromium alloy, cobalt-iron alloy, cobalt-phosphorus alloy, etc., the content of chromium, iron and phosphorus is preferably about 30% by weight or less.

In the present invention, as the lubricant, for example, a fatty acid organic compound, a fluorine organic compound, a silicon organic compound, or the like is used.

As the fatty acid-based lubricant, for example, fatty acid, metal salt of fatty acid, fatty acid ester, fatty acid amide and the like are used. Specific examples of the fatty acid include myristic acid, palmitic acid, oleic acid, stearic acid and behenic acid. Examples of these metal salts include lithium salt, sodium salt, calcium salt, magnesium salt, aluminum salt, iron salt, cobalt salt, zinc salt,
There are barium salt and lead salt.

Examples of the fatty acid ester include butyl stearate, stearic acid monoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride, and pentaerythritol tetrastearate.

Examples of the fatty acid amide include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, and methylenebisstearic acid amide.

Examples of fluorine-based lubricants include trichlorofluoroethylene, perfluoropolyether, and perfluoroalkylpolyether. Specific examples of commercially available products include Daiflon # 20 manufactured by Daikin Co., Ltd., Critex M, and Critex H manufactured by Dupont. Further, there is silicone oil as the silicone lubricant.

The lubricant layer may be composed of only the lubricant as described above, or the lubricant may be mixed with an additive such as a fluid paraffin or an anticorrosive to improve the corrosion resistance of the lubricant layer. It can also be improved.

Next, specific examples of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a vacuum vapor deposition apparatus according to an embodiment,
FIG. 2 is a sectional view of a magnetic recording medium manufactured by the method of the present invention, and FIGS. 3 and 4 are enlarged conceptual views of a ferromagnetic metal layer in the magnetic recording medium.

A base film 1 made of a polyethylene terephthalate film having a thickness of 12 μm, a roll 2 of the base film, and a vacuum deposition tank 3
Set inside. The base film 1 fed from the original roll 2 is wound around the peripheral surface of a cylindrical can 5 arranged in the center of the vacuum deposition tank 3 via a guide roller 4, and then wound up via the guide roller 4. It is wound up on a roll 6.

An evaporation source crucible 7 is disposed below the can 5, and a ferromagnetic metal 8 made of a cobalt-nickel alloy containing 20% by weight of nickel is set therein. A deposition preventive plate 9 is provided between the can 5 and the evaporation source crucible 7.

The decompression means 10 attached to the vacuum deposition tank 3 allows the inside of the tank to reach 5.0
After reducing the pressure to × 10 ^-6 Torr, oxygen gas is introduced into the tank from the oxygen gas supply pipe 11 at a flow rate of 180 ml / min. In such a state, the ferromagnetic metal 8 is vapor-deposited so that the ferromagnetic metal 8 is obliquely incident on the base film 1 moving along the peripheral surface of the can 5, and the ferromagnetic metal tank made of a cobalt-nickel alloy having a film thickness of 1500Å. 12 is formed and the winding roll 6 is continuously formed.
To be wound up. When the magnetic properties of the ferromagnetic metal layer 12 thus formed were measured, the coercive force was 1000 ersted and the squareness ratio was 0.7. As a result of Auger electron spectroscopy analysis, the average oxygen content concentration in the depth range from the surface layer to 100 Å was about 32 atomic%.

As described above, the ferromagnetic metal 8 is vapor-deposited so as to be obliquely incident, so that the columnar particles 13 are generated in an inclined state as shown in FIGS. 3 and 4. Since vapor deposition is performed in the presence of oxygen gas as described above, the intermediate layer 14 is formed around the columnar particles 13. The oxygen content concentration in the intermediate layer 14 is
It can be controlled by adjusting the amount of oxygen introduced. The method of blowing oxygen gas in the vacuum deposition tank will be described later in detail.

After the ferromagnetic metal layer 12 having a predetermined thickness is formed on the surface of the base film 1 as described above, the ferromagnetic metal layer 12 is taken out from the vacuum deposition tank 3 and heat-treated in the presence of at least oxygen gas and water. By this treatment, as will be described later in detail, the surface of the intermediate layer 14 is subjected to X-ray photoelectron spectroscopy analysis.
Coupling energy of Co ₂ p spectrum 780.0 ^{± 0.3} eV (2P3 /
2) and 795.6 when minus Batsukugurando a straight line so as to contact the low binding energy side rising point of the both peaks of ^{± 0.3} eV (2P1 / 2) to the through connexion spectrum, the peak height of 780.0 ^{± 0.3} eV 100 The peak height of 785.9 ^{± 0.3} eV is 40
It was as follows.

And the binding energy of its O ₁ s spectrum is 530.5 ^{± 2.5} eV
When the background is drawn with a straight line so as to come into contact with the spectrum through the rising points on the low binding energy side and the rising point on the high binding energy side of the complex peak in Fig. 3, the peaks on the low binding energy side and the high binding energy side of this complex peak The surface layer 15 is modified so that the ratio of the height of the side peaks is in the range of 100: 110-50 (Figs. 3 and 4).
See figure).

The formation state of the surface layer 15 depends on the heating and folding conditions when the surface layer 15 is formed, as shown in FIG.
May be formed on the entire periphery of the columnar particles, or may be formed only on the surface side portion of the columnar particles 13 as shown in FIG.

When the heat treatment is completed, the lubricant coating step is carried out, and the lubricant layer 16 is provided on the surface of the ferromagnetic metal layer 12 as shown in FIG. The thickness of the lubricant layer 16 is 30 to 1000Å
If the thickness is appropriate, and it is less than 30Å, it is difficult to exert the lubricating effect over a long period of time.On the other hand, if it is more than 1000Å, the electromagnetic conversion characteristics deteriorate, so the film thickness of the lubricant layer 16 is restricted to the above range. It is better to do.

The present inventors have studied a method of introducing an oxygen gas such as oxygen gas during oblique oblique deposition. As a result, if the oxidizing gas is blown toward the vapor stream of the ferromagnetic metal, the oxygen gas and the vapor stream collide with each other to cause scattering, and the incident angles of the vapor stream with respect to the base film are scattered. , Sufficient magnetic properties cannot be obtained. On the other hand, it was found that if the oxidizing gas is blown toward the base film passing through the lowest incident angle portion so as not to cross the vapor flow of the ferromagnetic metal, the above-mentioned problem is solved.

The method of introducing the oxidizing gas of the present invention is based on such knowledge. That is, when vapor deposition is performed by obliquely injecting a ferromagnetic metal vapor stream onto a base film that moves from a high-incidence bevel to a low-incidence bevel along the circumference of a cylindrical can, Oxidizing gas is blown from the upper side of the adhesion-preventing plate arranged below the can, so as to directly irradiate at least the base film passing through the minimum oblique angle. The angle of interaction between the oxidizing gas and the vapor flow of the ferromagnetic metal that is incident on this lowest incident angle portion does not exceed about 30 degrees, and the direct range of the oxidizing gas is higher than the lowest incident angle portion. The angle from the center of rotation of the cylindrical can in the direction of the incident angle should not exceed about 10 degrees.

By doing so, oxygen atoms can be reliably introduced into the intermediate layer between the columnar particle body of the columnar particles formed by oblique incidence vapor deposition and the surface layer, and the oxygen content concentration in the intermediate layer can be controlled. Is easy.

The surface layer of the columnar particles described in the present specification means a surface in which a ferromagnetic metal and oxygen are bonded, except for a contaminated layer on the surface where organic oxygen or oxygen in the air is bonded or attached. Means the part.

Next, the blowing of the oxidizing gas will be described with reference to the drawings.

As shown in FIGS. 1 and 5, a supply pipe 11 for introducing an oxidizing gas (oxygen gas) is installed inside the tip portion of the deposition-inhibitory plate 9. As shown in FIG. 5, the distance D from the gas outlet 11a of the supply pipe 11 to the lowest incident angle portion A of the base film 1 is within 15 cm, and the vapor flow of the ferromagnetic metal is directed at the lowest incident angle θ. The outlet 11a of the supply pipe 1 is provided at a position where the angle α with B is within about 30 degrees. Then, the oxidizing gas blown from the blowout port 11a is at an angle β with the rotation center O of the cylindrical can 5 as a base point in the direction from the lowest incidence angle portion A to the high incidence angle.
It is preferable to spray so as to directly hit within the range E which does not exceed the degree.

When the oxidizing gas is blown directly onto the base film 1 passing through at least the minimum incident angle portion A under such conditions, the oxidizing gas is the most near the minimum incident angle portion A. At the same time, in the vicinity of the maximum incident angle portion C, since the deposition rate of the ferromagnetic metal on the base film 1 is slow, the oxidizing gas is easily taken in. As a result, when nuclei of ferromagnetic particles are generated on the base film 1 near the maximum incident angle portion C, sufficiently small particles containing oxygen atoms are generated. Then, when the base film 1 passes through the minimum incident angle portion A, a large amount of oxidizing gas causes the particles to grow well.

Oxygen gas is suitable as the oxidizing gas, but a mixture of oxygen gas and other gas can also be used.

When the incident angle θ of the oblique incident vapor deposition of the ferromagnetic metal is larger than about 65 degrees, the vapor deposition efficiency is deteriorated and it is not suitable for mass production. Therefore, the incident angle θ is preferably 65 degrees or less.

Using the vacuum vapor deposition apparatus shown in FIG. 1, a base film 1 made of polyethylene terephthalate having a thickness of 12 μm
The original roll 2 is moved along the circumferential surface of the cylindrical can 5 having a diameter of 60 cm through the guide roller 4 to move the guide roller 4
Then, the evaporation source crucible 7 was set with a ferromagnetic metal 8 made of a cobalt-nickel alloy containing 20% by weight of nickel.

Then, the pressure inside the tank was reduced to 5.0 × 10 ⁻⁶ Torr by the pressure reducing means 10 to evaporate the ferromagnetic metal 8 by heating, and the minimum incident angle 50
At the same time, the oblique incident vapor deposition is started at a vapor deposition rate of 800 Å / sec, and at the same time, oxygen gas is blown from the supply pipe 11 to the base film 1 passing through the lowest incident angle portion A at various gas flow rates.
A ferromagnetic metal layer made of a cobalt-nickel alloy was formed on the base film 1.

The supply pipe 11 has a base film 1 wound around the cylindrical can 5 from its gas outlet 11a.
The distance to is 5 cm, and the angle α with the vapor flow directed at the minimum incident angle is 20 degrees. In addition, the oxygen gas blown out from the gas outlet 11a of the supply pipe 11 has an angle β with the rotation center of the cylindrical can 5 as the base point in the direction from the lowest incidence angle portion A to the high incidence angle.
It was made to be a direct shot at 10 degrees.

The magnetic recording medium thus obliquely incident and vapor-deposited is taken out of the vacuum vapor-deposition apparatus, heated at a treatment temperature of 60 ° C. and a relative humidity of 15% in a heat treatment tank for 100 hours while being kept at atmospheric pressure, and then subjected to a predetermined temperature. I made a magnetic tape by cutting it into widths.

As described above, when forming the ferromagnetic metal layer 12 on the base film 1, oxygen gas is blown at different flow rates to make magnetic tapes of various samples, and the oxygen content concentration and abrasion resistance of the intermediate layers in these various magnetic tapes are made. A test was conducted on the relationship with sex, and the results are shown in the following table.

The average oxygen content within 100 Å from the outermost surface of the magnetic tape is the average oxygen content measured from the surface to 100 Å from the surface by measuring the oxygen atom concentration while removing to a depth of 100 Å from the surface of the magnetic tape by etching. Turned into

In addition, the abrasion resistance test of the magnetic tape is 1/2 inch VHS
The still time was investigated using the method VTR.

As is clear from this table, when the oxygen content concentration in the intermediate layer is less than 20 atom%, the durability is poor, while when the oxygen content concentration is higher than 50 atom%, the wear resistance is deteriorated.
Therefore, the supply amount of oxidizing gas such as oxygen gas is controlled during the manufacturing process of the magnetic recording medium,
By controlling the average oxygen content concentration within 100Å within the range of 20 to 50 atomic%, a magnetic recording medium having abrasion resistance can be obtained.

Next, specific examples of the present invention will be described.

Example 1 As described above, 80 wt% of cobalt and 20 wt% of nickel were contained on the surface of the base film 1 made of polyethylene terephthalate, and the average oxygen concentration from the surface layer to 100 Å deep was 32 atom%. To form the ferromagnetic metal layer 12.

In this way, the base film 1 on which the ferromagnetic metal is obliquely incident and vapor-deposited is taken out from the vacuum vapor deposition tank 3 and treated in a heat treatment tank kept at atmospheric pressure at a treatment temperature of 60 ° C. and a relative humidity of 15%.
It was heat-treated for 100 hours, and after the treatment, it was cut into a predetermined width to prepare a magnetic tape.

Example 2 A magnetic tape was produced in the same manner as in Example 1 except that the treatment time was 200 hours.

Example 3 A magnetic tape was produced in the same manner as in Example 1 except that the treatment time was 500 hours.

Example 4 A magnetic tape was produced in the same manner as in Example 3 except that the treatment temperature was 40 ° C. and the relative humidity was 40%.

Example 5 A magnetic tape was produced in the same manner as in Example 1 except that the treatment temperature was 90 ° C., the relative humidity was 15%, and the treatment time was 50 hours.

Example 6 A magnetic tape was produced in the same manner as in Example 1 except that a lubricant layer of stearic acid, which is one kind of fatty acid, was formed on the high magnetic metal layer to a thickness of about 50Å after the heat treatment.

Example 7 A magnetic tape was produced in the same manner as in Example 4 except that a lubricant layer of stearic acid was formed on the ferromagnetic metal layer after the heat treatment to have a thickness of about 50Å.

Example 8 A magnetic tape was produced in the same manner as in Example 5 except that a lubricant layer of stearic acid was formed on the ferromagnetic metal layer to a thickness of about 50Å after the heat treatment.

Example 9 A lubricant layer of perfluoroalkylpolyether (product name: Clix H manufactured by Dyupon Co., Ltd.), which is one of fluorine-based organic compounds, was formed on the ferromagnetic metal layer after heat treatment to a thickness of about 50 Å. A magnetic tape was prepared in the same manner as in Example 1.

Example 10 A magnetic layer was formed in the same manner as in Example 4 except that after the heat treatment, a lubricant layer of perfluoroalkylpolyether (product name Critex H manufactured by Dyupon Co., Ltd.) was formed on the ferromagnetic metal layer to a thickness of about 50 Å. I made a tape.

Example 11 A magnetic layer was formed in the same manner as in Example 5 except that after the heat treatment, a lubricant layer of perfluoroalkylpolyether (product name Critex H manufactured by Dyupon Co., Ltd.) was formed on the ferromagnetic metal layer to a thickness of about 50 Å. I made a tape.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1 except that the heat treatment was omitted.

Comparative Example 2 A magnetic tape was produced in the same manner as in Comparative Example 1 except that the heat treatment was omitted and the lubricant layer of stearic acid was formed to a thickness of about 50Å.

Comparative Example 3 Except that heat treatment was performed at 60 ° C. and 90% RH for 50 hours,
A magnetic tape was produced in the same manner as in Example 1.

Comparative Example 4 A magnetic tape was prepared in the same manner as in Comparative Example 3 except that a lubricant layer of stearic acid was formed on the ferromagnetic metal layer to a thickness of about 50Å after the heat treatment.

Comparative Example 5 In a vacuum deposition tank, a cobalt (80% by weight) -nickel (20% by weight) alloy was obliquely incident and deposited on a base film to form a ferromagnetic metal layer. Then, the magnetic tape was taken out from the vacuum vapor deposition tank and heated steam of 100 ° C. or higher was blown onto the surface of the ferromagnetic metal layer to prepare a magnetic tape.

FIG. 6 is a diagram showing the change over time in the friction coefficient of the magnetic tapes obtained according to each of the examples and the comparative examples.
The friction coefficient was measured using a sliding dynamic friction coefficient measuring machine, and the initial friction coefficient and each magnetic tape were measured at 60 ° C and 90% RH.
The friction coefficient after storage for 1 week in a high temperature and high humidity atmosphere was measured. Line A in the figure is the magnetic tape obtained in Examples 1 to 5, line B is the magnetic tape obtained in Examples 6 to 8, and line C is the magnetic tape obtained in Examples 9 to 11. The obtained magnetic tape, line D is the magnetic tape obtained in Comparative Example 1, line E is the magnetic tape obtained in Comparative Example 2, and line F
Is the characteristic curve of the magnetic tape obtained by Comparative Example 3, line G is the magnetic tape obtained by Comparative Example 4, and line H is the characteristic curve of the magnetic tape obtained by Comparative Example 5.

As is clear from this figure, Comparative Examples 1, 2, 3, 4, 5
When stored in a high temperature and high humidity atmosphere for a long time, the friction coefficient tends to increase sharply. On the other hand, all the magnetic recording media according to the present invention show almost no change over time in the friction coefficient and have a stable and low friction coefficient at all times, so that the running property is very good. Further, since the average oxygen content concentration within 100Å from the outermost surface is regulated within the range of 20 to 50 atomic%, the initial wear resistance is retained even when stored in a high temperature and high humidity atmosphere. .

Next, XPS analysis of the surface of the ferromagnetic metal layer of the magnetic tape obtained in Example 1 was performed. VG Sc for XPS analysis
Using an analytical instrument with product name ESCALAB5 manufactured by ientific Limited, X-ray output is 10kV, 20mA, C ₁ s peak value is 284.6eV.
The analysis was performed by setting the escape angle to zero.

FIG. 7 is a spectrum diagram of Co ₂ p3 / 2 based on the XPS analysis,
FIG. 8 is a spectrum diagram of O ₁ s, and FIG. 9 is a spectrum diagram obtained by subtracting a back ground grain from the spectrum diagram of FIG.

As is clear from these figures, in the case of the magnetic recording medium obtained according to Example 1, the binding energy of the Co ₂ p spectrum in the X-ray photoelectron spectroscopy analysis of the surface layer of the ferromagnetic metal layer was 780.0 ^{± 0.3} eV (2P3 / 2) and 795.6 ^{± 0.3} eV (2
(P1 / 2) A straight line that touches the spectrum through the rising points on the low binding energy side of both peaks (P1 / 2).
When G is subtracted (see Fig. 7), the main peak (780.0
The peak height H2 of the satellite peak (785.9 ^{± 0.3} eV) is about 25, where the peak height H1 of ^{± 0.3} eV) is 100.

In addition, as shown in Fig. 8, the background is a straight line that is in direct contact with the spectrum through the rising points on the low and high binding energy sides of the combined peak at the binding energy 530.5 ^{± 2.5} eV of the O ₁ s spectrum. When BG is subtracted, the ratio of the height of the low binding energy side peak to the height of the high binding energy side peak (H3 to H4) of this complex peak is 100 to about 71, as shown in FIG.

The ferromagnetic metal layers are also heat-treated in the presence of oxygen and water in Comparative Examples 3 to 5, but as a result of X-ray photoelectron spectroscopy analysis, the value of H2 when H1 is 100 is that in Comparative Example 3. The values were 48, 47 in Comparative Example 4, and 51 in Comparative Example 5. Further, when H3 was set to 100, the value of H4 was 350 in Comparative Example 3, 400 in Comparative Example 4, and 500 in Comparative Example 5.

If the peak height H2 of the satellite peak when the above-mentioned peak height H1 is set to 100 is larger than 40, the corrosion resistance is insufficient and the runnability in high temperature and high humidity tends to deteriorate with time, so the main Peak (780.0 ^{± 0.3} eV) peak height H1
It is necessary to keep the peak height H2 of the satellite peak (785.9 ^{± 0.3} eV) set to 100 below 40.

Further, in the O ₁ s spectrum, the ratio of the peak height of the low binding energy side peak (attributed to the oxide oxygen) to the H3 high binding energy side peak (attributed to the hydroxyl group of oxygen) H4 is 10
If it is larger than 0/110, the running durability is poor even if the above-mentioned Co2P3 / 2 spectrum is within the above range. The reason for this has not been fully clarified, but it is thought that it is because cobalt exists in a state close to hydroxide having high viscosity.

On the other hand, in the region where the ratio of H3 / H4 is less than 100/50, it is considered that the formation of the surface layer undergoes a kind of dehydration process,
There is a problem in terms of productivity because long-term processing is required.

FIG. 7 to FIG. 9 show spectrum diagrams of the magnetic recording medium of Example 1. In the magnetic recording medium according to other Examples, the ratio of H1 to H2 in the X-ray photoelectron spectroscopic analysis was 10 as well.
It was confirmed by the above analysis that the ratio of 0:40 or less and H3: H4 falls within the range of 100: 50 to 110.

In the magnetic recording medium of the present invention, it is considered essential for the surface layer to contain a hydroxyl group for the corrosion resistance. This is because the surface layer has an amorphous network structure containing hydroxyl groups, which is considered to prevent the diffusion of cations. Therefore, in the present invention, it is necessary that the spectral characteristics of cobalt and oxygen are within the above-mentioned ranges, which provides both excellent durability and corrosion resistance.

〔The invention's effect〕

The present invention has the above-mentioned structure, and can provide a magnetic recording medium excellent in both corrosion resistance and abrasion resistance.

Further, since the amorphous layer formed on the surface of the ferromagnetic metal layer is extremely thin and does not develop to the deep part of the ferromagnetic metal layer, there is no concern about deterioration of magnetic characteristics as conventionally proposed.

Further, in the case where the lubricant layer is formed on the ferromagnetic metal layer, the ferromagnetic metal layer formed by applying the lubricant has a chemically stable amorphous layer formed on the surface of the ferromagnetic metal layer. The lubricant selection range can be expanded without having to consider the chemical influence on the lubricant. That is, when a lubricant of a weak organic acid such as fatty acid is used in the conventional magnetic recording medium, the ferromagnetic metal layer is chemically affected by the organic acid, and the friction coefficient significantly increases with time. This limits the types of lubricants that can be used. On the other hand, in the magnetic recording medium of the present invention, since the surface layer having resistance to weak acid is present in the surface side portion of the ferromagnetic metal layer, the selection range of the lubricant is smaller than that of the conventional one. It has the feature of being expandable.

BRIEF DESCRIPTION OF THE DRAWINGS All of the drawings are for explaining the present invention. FIG. 1 is a schematic configuration diagram of a vacuum vapor deposition apparatus used in Examples, FIG. 2 is an enlarged sectional view of a magnetic recording medium, and FIG. 4 and FIG. 4 are enlarged conceptual diagrams of the ferromagnetic metal layer, FIG. 5 is an explanatory diagram showing an example of blowing an oxidizing gas, and FIG. 6 is a characteristic diagram showing changes in friction coefficient of each sample tape. FIG. 7, FIG. 8 and FIG. 9 are spectrum diagrams by XPS analysis of the surface layer. 1 ... Base film, 3 ... Vacuum deposition tank, 8 ... Ferromagnetic metal, 11 ... Oxygen gas supply pipe, 12 ... Ferromagnetic metal layer,
13 …… Columnar particles, 14 …… Intermediate layer, 15 …… Surface layer, 16 ……
Lubricant layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Isoe 1-88 No. 1-Tora, Tora, Ibaraki-shi, Osaka Inside Hitachi Maxell Co., Ltd. (56) Reference JP-A-60-157728 (JP, A) 42-20025 (JP, B1)

Claims (4)

[Claims] 1. In a magnetic recording medium in which a ferromagnetic metal layer containing cobalt as a main component is formed on a non-magnetic substrate by oblique vapor deposition, a Co _{2 P} spectrum in an X-ray photoelectron spectroscopic analysis of the surface layer of the ferromagnetic metal layer is obtained. Binding energy 780.0 ^{± 0.3} eV (2P3 /
2) and 795.6 ^{± 0.3} eV (2P1 / 2) both peaks of 780.0 ^{± 0.3} eV when the back ground is drawn with a straight line so as to contact the spectrum through the rising points on the low binding energy side. The peak height of 785.9 ^{± 0.3} eV is 100 or less, and the binding energy of its O _1S spectrum is 530.5 ^{± 2.5} eV.
When the background is drawn with a straight line so as to come into contact with the spectrum through the rising points on the low binding energy side and the rising point on the high binding energy side of the complex peak in Fig. 3, the peaks on the low binding energy side and the high binding energy side of this complex peak A magnetic recording medium characterized in that the height ratio of side peaks is regulated within the range of 100 to 110 to 50, and the surface layer of the ferromagnetic metal layer is amorphous containing a hydroxyl group. 2. In a magnetic recording medium in which a ferromagnetic metal layer containing cobalt as a main component is formed on a non-magnetic substrate by oblique vapor deposition, a Co _{2 P} spectrum of an X-ray photoelectron spectroscopy analysis of the surface layer of the ferromagnetic metal layer is performed. Binding energy 780.0 ^{± 0.3} eV (2P3 /
2) and 795.6 ^{± 0.3} eV (2P1 / 2) both peaks of 780.0 ^{± 0.3} eV when the back ground is drawn with a straight line so as to contact the spectrum through the rising points on the low binding energy side. The peak height of 785.9 ^{± 0.3} eV is 100 or less, and the binding energy of its O _1S spectrum is 530.5 ^{± 2.5} eV.
When the background is drawn with a straight line so as to come into contact with the spectrum through the rising points on the low binding energy side and the rising point on the high binding energy side of the complex peak in Fig. 3, the peaks on the low binding energy side and the high binding energy side of this complex peak The side peak height ratio is regulated in the range of 100 to 110 to 50, the surface layer of the ferromagnetic metal layer is amorphous containing hydroxyl groups, and the lubricant layer is formed on the amorphous surface layer. A magnetic recording medium comprising: 3. In claim (2),
A magnetic recording medium, wherein the lubricant layer contains at least one fatty acid-based organic compound. 4. In the scope of claim (2),
A magnetic recording medium, wherein the lubricant layer contains at least one fluorine-based organic compound.