JPH08194933A - Magnetic recording medium, its manufacture and its manufacturing apparatus - Google Patents

Abstract

PURPOSE: To obtain a metal thin film type magnetic recording medium which facilitates the improvement of static noise generated during recording and reproduction as the improvement of the practical reliability and which facilitates the improvement of still durability after the exposure to a high temperature and high humidity atmosphere. CONSTITUTION: A ferromagnetic metal thin film 2, a diamond carbon film 4 and a lubricant layer 5 are successively formed on one of the surfaces of a nonmagnetic substrate 1. A back-coating layer 3 is formed on the other surface of the substrate 1 and a metal-containing thin film 6 whose thickness is 0.01-5.0nm and whose surface resistance is 10<2> -10<8> Ω/sq. is formed on the back- coating layer 3 by a sputtering method, a reactive deposition method or a plasma CVD method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic metal type magnetic recording medium, a manufacturing method thereof and a manufacturing apparatus thereof. In particular, the present invention relates to a magnetic recording medium having a thin film provided on a back coat layer used for improving practical reliability, particularly weather resistance, a method for producing the same, and an apparatus for producing the same.

[0002]

2. Description of the Related Art Ferromagnetic metal thin film type magnetic recording media are inherently superior to conventional coating type magnetic recording media due to their high packing density of the magnetic layer and low recording / reproducing loss due to thinning of the magnetic layer. It is suitable for high recording density, but since the magnetic layer (recording layer) is a metal thin film, it has a defect that it is easily scraped and rusted peculiar to metal. Therefore, in order to overcome these, improve durability, corrosion resistance, etc. by various methods,
Development has continued to improve practical reliability and put it into practical use. For example, a method of providing a carboxylic acid-based or phosphoric acid-based lubricant on the ferromagnetic metal thin film, a method of providing a non-magnetic metal protective film on the ferromagnetic metal thin film, and an oxide protective film such as silica. A method of providing is known.

Further, a diamond-like carbon film as a protective film and Japanese Patent Laid-Open No. 62-219314 with an organic lubricant, and a diamond-like carbon film (hard carbon film) and a plasma polymerized film as a protective film are provided. Kaihei 2-1371
No. 16 publication is disclosed, and it is known that the corrosion resistance is significantly improved.

However, since the diamond-like carbon film and the plasma polymerized film are chemically extremely stable, they have a weak affinity with the lubricant provided on them. Therefore, the lubricant migrates onto the back coat layer under a high temperature and high humidity environment, which causes a problem in durability.

As a means for solving these problems, there is JP-A-4-222922 in which a metal-containing plasma polymerized film is provided on a diamond-like carbon film. According to the present invention, the migration of the lubricant on the back coat layer is improved. Further, JP-A-4-48520 and the like in which a fluorine-containing plasma polymerized film is provided on the back coat layer are also known.

[0006]

However, in the conventional magnetic recording medium in which the metal-containing plasma polymerized film is provided on the diamond-like carbon film, the metal is present near the surface of the magnetic recording medium. By wearing, the still durability in a low humidity environment is extremely reduced. Therefore, as the practical performance of the video tape recorder, the still durability under a low humidity environment is significantly reduced.

Further, in the magnetic recording medium provided with the fluorine-containing plasma polymerized film on the back coat layer, some improvement in durability under high temperature and high humidity environment is recognized, but when left in the high temperature and high humidity environment, lubrication occurs. The agent still has a problem that the agent migrates onto the back coat layer, and particularly the still durability is lowered. In addition, when left in a high-temperature and high-humidity environment, not only the durability of the still image deteriorates, but also electrostatic noise is generated during recording and reproduction in a low-humidity environment.

In order to solve the above problems, the present invention holds a certain amount of a lubricant formed on a diamond-like carbon film on a back coat layer at the time of manufacturing a magnetic recording medium, and at the same time, on the diamond-like carbon film, With a structure that does not contain metal, as a practical performance for video tape recorders, it improves still durability under low humidity environment and still durability after left in high temperature and high humidity environment, and also improves surface resistance on the back coat layer. It is an object of the present invention to provide a magnetic recording medium that is optimized and has improved electrostatic noise during recording and reproduction, a method for manufacturing the same, and a manufacturing apparatus for the same.

[0009]

In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a ferromagnetic metal thin film, a diamond-like carbon film, and a lubricant layer sequentially provided on one surface of a non-magnetic substrate, A back coat layer is provided on the other surface, and a thin film containing metal atoms on the back coat layer (metal-containing thin film)
Is provided.

In the magnetic recording medium, the thin film containing metal atoms is preferably at least one substance selected from metal oxides, metal nitrides, metal carbides and metal borides.

In the magnetic recording medium, the thin film containing metal atoms is preferably a metal-containing organic compound. Further, in the magnetic recording medium, the surface resistance of the thin film containing metal atoms is preferably 10 ² to 10 ⁸ Ω / □.

In the magnetic recording medium, the thin film containing metal atoms preferably has a thickness of 0.01 to 5.0 nm. The method of manufacturing a magnetic recording medium of the present invention comprises forming a ferromagnetic metal thin film on one surface of a non-magnetic substrate, forming a back coat layer on the other surface, and then forming a plasma on the ferromagnetic metal thin film in a vacuum chamber. CVD (plasma chemical va
por deposition) to form a diamond-like carbon film,
Then, a thin film containing metal atoms is formed on the back coat layer.

In the method of manufacturing the magnetic recording medium of the present invention, the thin film containing the metal atoms is formed in the same vacuum chamber as the diamond chamber for forming the diamond-like carbon film, and then the diamond-like carbon film is formed. It is preferable to continuously form.

In the method of manufacturing the magnetic recording medium, it is preferable that the thin film containing the metal atom is formed by a sputtering method or a reactive vapor deposition method. Further, in the method of manufacturing the magnetic recording medium, it is preferable that the diamond-like carbon film is formed, and subsequently, a thin film containing metal atoms is continuously formed on the back coat layer by plasma CVD in the same vacuum chamber.

The magnetic recording medium manufacturing apparatus of the present invention is an apparatus for transferring a magnetic recording medium having a ferromagnetic metal thin film formed on one surface of a non-magnetic substrate and a back coat layer formed on the other surface. And plasma CVD on the ferromagnetic metal thin film.
A roller for supporting and transporting the magnetic recording medium for forming a diamond-like carbon film by a method, and a discharge tube,
A plasma CVD apparatus provided with an electrode and a gas inlet is provided, and a film forming apparatus for forming a thin film containing metal atoms on the back coat layer, and a transfer apparatus for transferring the magnetic recording medium to the film forming apparatus. When forming a thin film containing metal atoms, a roller for supporting and transferring the magnetic recording medium is provided in the same vacuum chamber, and the film forming apparatus is provided with a sputtering target and a gas introduction port. The sputtering apparatus, or the reactive vapor deposition apparatus provided with a crucible, a shutter, a deposition preventive plate, an evaporation material heating device, and a gas inlet.

In the magnetic recording medium manufacturing apparatus,
The film forming apparatus is preferably a plasma CVD apparatus equipped with a discharge tube, an electrode, and a gas inlet.

[0017]

According to the metal thin film type magnetic recording medium having the above-mentioned constitution of the present invention, the metal-containing thin film is provided on the back coat layer to have an optimum thickness, and the lubricant is provided on the diamond-like carbon film. Has a functional group with a high affinity for metals, it means that a certain amount is chemically retained on the surface of the backcoat layer, and even if it is left in a high temperature and high humidity environment, most of the lubricant is Without moving, there is almost no deterioration in still durability. Further, since no metal is present on the diamond-like carbon film that slides on the magnetic head, there is no adhesion phenomenon and the still durability in a low humidity environment is greatly improved. Further, it becomes possible to reduce the surface resistance of the surface on the back coat layer side, and it is also possible to improve electrostatic noise due to charging during recording and reproduction.

According to a preferred example of the magnetic recording medium, in which the metal of the thin film containing metal atoms is at least one substance selected from metal oxides, metal nitrides, metal carbides and metal borides, these metals are A certain amount can be easily retained on the surface of the back coat layer, and it will be chemically retained on the back coat layer, and even if left in a high temperature and high humidity environment, the lubricant hardly moves, A magnetic recording medium with reduced deterioration of still durability can be obtained.

According to a preferable example of the magnetic recording medium in which the thin film containing metal atoms is a metal-containing organic compound, a metal-containing thin film can be easily formed. In the magnetic recording medium, the metal atom of the thin film containing a metal is preferably chromium oxide. With such a structure, the magnetic recording is particularly easy to form, and the deterioration of the still durability is reduced in a wide range of film thickness. The medium can be obtained.

In the magnetic recording medium, the metal atom of the thin film containing metal atoms is preferably titanium.
With such a configuration, it is possible to form a metal-containing thin film that is less affected by the forming method.

According to a preferable example in which the magnetic recording medium has a surface resistance of a thin film containing metal atoms of 10 ² to 10 ⁸ Ω / □, the surface resistance of the surface on the backcoat layer side can be reduced, and recording Generation of electrostatic noise due to charging during reproduction can be improved.

Further, in the magnetic recording medium, the thickness of the thin film containing metal atoms is 0.01 to 5.0 nm, but according to the preferable example, the thin film containing metal can be easily formed and the surface thereof can be easily formed. The resistance can be set within a required range, and electrostatic noise due to charging during recording / reproduction can be improved.

According to the method of manufacturing a magnetic recording medium of the present invention, a ferromagnetic metal thin film is formed on one surface of a non-magnetic substrate, a back coat layer is formed on the other surface, and then a strong magnetic layer is formed in a vacuum chamber. A diamond-like carbon film is formed on the magnetic metal thin film by a plasma CVD method, and subsequently, a thin film containing metal atoms is formed on the back coat layer. Therefore, it is possible to obtain a highly reliable magnetic recording medium in which each thin film, particularly a metal-containing thin film, can be easily formed, a decrease in still durability is reduced, and electrostatic noise is improved.

In the method for producing a magnetic recording medium, a preferable example in which the thin film containing the metal is continuously formed in the same vacuum chamber as that for forming the diamond-like carbon film subsequent to the formation of the diamond-like carbon film. According to this, a metal-containing thin film can be easily formed at low cost, and as a result, a highly reliable magnetic recording medium with reduced deterioration of still durability, improved electrostatic noise, can be obtained at low cost. it can.

According to a preferred example of forming a thin film containing metal atoms by a sputtering method or a reactive vapor deposition method in the method of manufacturing a magnetic recording medium having the above-mentioned structure, a certain amount of metal atoms are retained on the surface of the back coat layer. In addition, a dense metal-containing thin film having a strong affinity for the lubricant can be easily formed at low cost. As a result, even if left in a high temperature and high humidity environment, the lubricant hardly moves, there is almost no deterioration in still durability, electrostatic noise is improved, and a highly reliable magnetic recording medium is manufactured at low cost. can do.

In the method of manufacturing a magnetic recording medium having the above-mentioned structure, a diamond-like carbon film is formed, and subsequently, a thin film containing metal atoms is continuously formed on the back coat layer by plasma CVD in the same vacuum chamber. According to a preferred example, a certain amount of metal is retained on the surface of the back coat layer,
It is possible to easily form a dense metal-containing thin film that does not intensify this movement even for a lubricant layer having a wide thickness range. As a result, even if left in a high temperature and high humidity environment, the lubricant hardly moves, and the durability of the steel is hardly deteriorated, and the magnetic recording medium with improved electrostatic noise can be manufactured at low cost. .

According to the magnetic recording medium manufacturing apparatus of the present invention,
An apparatus for transferring a magnetic recording medium having a ferromagnetic metal thin film formed on one surface of a non-magnetic substrate and a back coat layer formed on the other surface, and a plasma CVD method on the ferromagnetic metal thin film. To form a diamond-like carbon film,
A film forming apparatus for arranging a roller for supporting and transferring the magnetic recording medium, a plasma CVD apparatus having a discharge tube, an electrode, and a gas introduction port, and further forming a thin film containing metal atoms on the back coat layer. A transfer device for transferring the magnetic recording medium to a film forming apparatus, and a roller for transferring the magnetic recording medium while supporting the magnetic recording medium when forming a thin film containing metal atoms are provided in the same vacuum chamber, The film forming device is a sputtering target, a sputtering device equipped with a gas inlet, or a crucible, a shutter, a deposition preventive plate, an evaporation material heating device, and a reactive vapor deposition device equipped with a gas inlet. Since the thin film is continuously formed on the front and back sides in the same vacuum chamber as described above, it is possible to easily and inexpensively manufacture the high-quality magnetic recording medium as described above with a small apparatus. You can

Further, in the magnetic recording medium manufacturing apparatus of the present invention,
According to a preferable example in which the film forming apparatus is a plasma CVD apparatus including a discharge tube, an electrode, and a gas inlet, as described above,
A high-quality magnetic recording medium can be easily and inexpensively manufactured with a small device.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view showing the basic structure of a magnetic recording medium of the present invention. In FIG. 1, 1 is a non-magnetic substrate,
A ferromagnetic metal thin film 2 is provided on one surface of a non-magnetic substrate 1, a diamond-like carbon film 4 and a lubricant layer 5 are sequentially provided on the ferromagnetic metal thin film 2, and a back coat layer 3 is provided on the other surface.
The metal-containing thin film 6 is formed on this.

As the non-magnetic substrate 1, a plastic film of 2 to 20 μm polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide or the like, a metal substrate of aluminum or the like, or a glass substrate or the like is used.

The ferromagnetic metal thin film 2 has a thickness of 0.05 to 0.3 μm.
m-thickness of Co-Ni-O, Co-Ni-Cr, Co-
O or the like is used and is formed by a vacuum processing method such as a vacuum vapor deposition method or a sputtering method.

The back coat layer 3 is made of polyester resin or polyurethane resin, carbon, calcium carbonate,
It is formed by applying a mixture such as nitrocellulose.
The diamond-like carbon film 4 is formed into a film thickness of 5 to 20 nm by a plasma CVD method by introducing a mixed gas of an inert gas and a hydrocarbon. If the thickness is less than 5 nm, it is too thin and is easily scraped off, and durability cannot be secured. On the other hand, if it exceeds 20 nm, a spacing loss occurs, and the electromagnetic conversion characteristics of the magnetic recording medium cannot be maintained.

As the lubricant layer 5, a fluorine-containing carboxylic acid alone or a mixture with a fluorine-containing carboxylic acid ester is used, and the lubricant layer 5 is provided to have a film thickness of 10 to 80 nm. If the thickness is less than 10 nm, the magnetic head or the like scratches the surface and the durability is reduced. Further, if it exceeds 80 nm, an adsorption phenomenon occurs and running stability deteriorates.

The metal-containing thin film 6 is made of, for example, titanium, chromium,
A metal containing a metal atom such as manganese or iron, a metal oxide, a metal nitride, a metal carbide, a metal boride alone or a mixture, or a metal-containing organic compound is used, and a sputtering method, a reactive vapor deposition method, or plasma CVD is used. 0.01 by method
It is formed to a film thickness of ˜5 nm. When the thickness is less than 0.01 nm, the surface resistance is high, the electrostatic noise is not improved, and the transfer of the lubricant to the back surface is not improved. On the other hand, when the thickness exceeds 5 nm, the amount of the lubricant layer held on the back surface becomes too large, which is the same as the movement to the back surface.

FIG. 2 and FIG. 3 are schematic configuration diagrams of one embodiment of the manufacturing apparatus for explaining the manufacturing method and the manufacturing apparatus of the metal-containing thin film of the magnetic recording medium of the present invention. FIG. 2 is a schematic view showing an example of the apparatus configuration in the method of forming the metal-containing thin film 6 by the sputtering method.

In FIG. 2, reference numeral 21 denotes a feeding roller, which is a magnetic recording medium 2 having a ferromagnetic metal thin film 2 on one surface and a back coat layer 3 on the other surface on a non-magnetic substrate 1.
0 is mounted and the magnetic recording medium 20 is sent out while controlling the tension.

Pass rollers 22, 24 to 27 and 29 are in contact with the magnetic recording medium 20 and rotate. Reference numeral 23 is a first main roller, the surface temperature of which is kept constant, the rotation of which is controlled so that the magnetic recording medium 20 can be conveyed at a constant speed, and is insulated from the main body of the apparatus. A diamond-like carbon film 4 is formed on the ferromagnetic metal thin film 2 by plasma CVD on the first main roller 23.

28 is a second main roller, which has the same specifications as the first main roller 23,
Then, the metal-containing thin film 6 is formed on the back coat layer 3 by sputtering.

Reference numeral 30 denotes a take-up roller, which continuously forms the magnetic recording medium 20 in which the diamond-like carbon film 4 is formed on the ferromagnetic metal thin film 2 and the metal-containing thin film 6 is formed on the back coat layer 3. It is a device for winding up and the tension is controlled similarly to the feeding roller 21.

Reference numeral 31 denotes a vacuum tank, which is formed airtight so as to maintain a required degree of vacuum, and main constituent elements are arranged in the tank. 32 is a vacuum pump, and various pumps are used according to the required degree of vacuum and the exhaust speed.
Is evacuated.

Reference numeral 33 is a first discharge tube, and 34 is a first electrode. The voltage applied from the first power source 36 to the first electrode 34 and the first electrode
The introduction gas from the gas introduction port 35 generates plasma in the first discharge tube 33 between the ferromagnetic metal thin film 2 of the magnetic recording medium 20. The first discharge tube 33 is a means for containing the plasma, preventing the surfaces of the vacuum chamber 31 and the magnetic recording medium 20 from being exposed to the plasma, and effectively utilizing the plasma.

A maximum of 2 SLM (standard state liter / minute) of raw material gas is supplied to the first gas inlet port 5 at a rate of 5 to 0.0005.
It can be introduced with a partial pressure of Torr. The first power supply 36 is used for plasma CVD, and has a direct current or an alternating current (50 Hz to
300MHz) or their superposition of 0.05 to 7
A voltage of kV can be applied, and the capacity is 5 kW each.

Reference numeral 37 is a sputter target, and metal oxide, metal nitride, metal carbide, metal boride and the like are used. Reference numeral 38 denotes a second gas inlet, into which an inert gas such as Ar can be mainly introduced at a pressure of 5 to 0.0005 Torr.

Reference numeral 39 denotes a first adhesion preventing plate which prevents the sputtered metal compound molecules from excessively adhering to the inner wall of the vacuum chamber 31 and the magnetic recording medium 20 being transferred. Reference numeral 40 is a second power source, which is used for sputtering, and which is the first power source 36.
DC or AC (50Hz to 300MHz),
Alternatively, a voltage of −0.05 to −7 kV can be applied by superimposing them, and the capacity is 5 kw each.

FIG. 3 is a schematic diagram showing an example of an apparatus in a method for forming the metal-containing thin film 6 by the reactive vapor deposition method. 3 is different from FIG. 2 only in that the means for forming the metal-containing thin film 6 is changed from the sputtering apparatus to the reactive vapor deposition apparatus, and other configurations are the same as those in FIG. The parts corresponding to the parts are denoted by the same reference numerals and only the description of the changed parts is given, and the detailed description is omitted.

Reference numeral 51 is a crucible, and a heat resistant material such as zirconia or carbon is used. 52 is an evaporation material,
Cr, Ti, etc. are filled as the metal contained in the metal-containing thin film 6.

Reference numeral 53 is a third gas inlet, which has a maximum of 2 LS.
A gas containing M oxygen, nitrogen, carbon or boron can be supplied. Reference numeral 54 denotes a shutter, which is closed during melting of the evaporation material to prevent deterioration of the magnetic recording medium 20 due to radiant heat, and is opened when the evaporation material reaches a prescribed evaporation rate, and is a back coat layer of the magnetic recording medium 20. A thin film (metal-containing thin film 6) of a metal compound in which the evaporated metal and the supply gas have reacted is formed on the surface 3.

Reference numeral 55 denotes a second deposition-inhibitory plate, and the evaporated metal vapor is used for the inner wall of the vacuum chamber 31 and the magnetic recording medium 2 being transferred.
It is a means for preventing excessive attachment to 0. The third power source 56 is used for melting the evaporation material 52 and is an induction heating source or an electron beam generating source, and the maximum output is 100 k.
w.

The magnetic recording medium configured as described above, its manufacturing method, and its manufacturing apparatus will be described in detail, including its operation, with reference to FIGS. 1, 2 and 3. Polyethylene terephthalate having a width of 500 mm and a thickness of 7 μm and a surface on the side on which the ferromagnetic metal thin film 2 is to be formed with Rmax of 15 nm is used as the non-magnetic substrate 1, and oxygen is formed on one surface by the oblique vacuum deposition method. While introducing, a ferromagnetic metal thin film 2 made of Co is formed to a thickness of 100 nm, and then on the other surface, a solid content made of polyester resin, nitrocellulose, and carbon is dissolved in a solvent containing methyl ethyl ketone as a main component, and wet. The backcoat layer 3 was formed by a coating method so that the thickness after drying was about 0.5 μm.

Subsequently, the magnetic recording medium 20 having the ferromagnetic metal thin film 2 formed on one surface and the back coat layer 3 formed on the other surface of the non-magnetic substrate 1 as shown in FIG. After loading to the take-up roller 30, the vacuum chamber 31 is evacuated to a specified vacuum degree (1 × 10 ⁻⁵ Torr) by the vacuum pump 32.

In the vacuum chamber 31, the feeding roller 21
The magnetic recording medium 20 mounted on the recording medium 20 passes through the pass roller 22, the first main roller 23, the pass rollers 24 to 27, the second main roller 28 and the pass roller 29, and is about 3 kg.
It is continuously wound around the winding roller 30 under the control of the tension of f.

While passing the first main roller 23,
The diamond-like carbon film 4 is formed on the ferromagnetic metal thin film 2 facing the first electrode 34 corresponding to the position of the first discharge tube 33. Specifically, Ar gas and ethane gas are mixed at a ratio of 1: 3 from the first gas inlet port 35, and the pressure is 0.05 Torr.
It is introduced into the first discharge tube 33 at 100k from the first power source 36.
AC power of 2 kw and DC power of 1.5 kw are supplied to generate a plasma discharge between the ferromagnetic metal thin film 2 of the magnetic recording medium 20 and the first electrode 34 to decompose the source gas from the gas inlet and to generate a strong gas. A diamond-like carbon film 4 having a thickness of about 15 nm is formed on the magnetic metal thin film 2.

Further, in the vacuum chamber 31, the magnetic recording medium 20 passes through the pass rollers 24 to 27, travels on the second main roller 28 so that the back coat layer 3 is on the outer side, and on the back coat layer 3. The metal-containing thin film 6 is formed. The metal-containing thin film 6 is attached as the sputter target 37, and the second gas introduction port 3 of the sputter target 37 is attached.
Samples of various thicknesses were prepared by introducing Ar gas at a pressure of 0.03 Torr from 8 and supplying high frequency power having a frequency of 13.56 MHz from the second power supply 40 and adjusting the supplied power by the sputtering method. did. The metal-containing thin film 6
Examples of the material include CrO ₂ , TiN, TiC, Mn ₂ B
Was used. CrO ₂ has a film thickness of 0.01 to 5.0 nm
7 samples in the range of, and samples of TiN, TiC, and Mn ₂ B each having a film thickness of 1.0 nm were prepared.

A method of forming the metal-containing thin film 6 by the reactive vapor deposition method will be described with reference to FIG. Up to the point where the magnetic recording medium 20 runs on the second main roller 28 with the back coat layer 3 outside, the process is exactly the same as in the example shown in FIG. 2, so only the reactive vapor deposition portion will be described.

Cr is filled in the crucible 51 as the evaporation material 52, and while the Cr is melted and evaporated by the high frequency power from the third power source 56, about 0.5 oxygen is supplied from the third gas introduction port 53.
Three samples of the metal-containing thin film 6 were produced in a thickness range of 0.1 to 3.0 nm by supplying the SLM to generate CrO ₂ and adjusting the evaporation rate. As still another example, Ti is used as the evaporative emission material 52, and nitrogen gas of 0.
A sample was also prepared in which 2 SLM was supplied to generate TiN, the evaporation rate was adjusted, and the metal-containing thin film 6 having a thickness of 1.0 nm was formed.

Wet coating of the sample prepared as described above
Fluorine-containing carboxylic acid, C _FiveF₁₁(CH₂)_TenC
OOH is deposited on the diamond-like carbon film 4 to a thickness of about 3.0 nm.
To form the lubricant layer 5 to complete the magnetic recording medium 20.
Then, it is cut into 8 mm width with a slitter device and various physical properties are tested.
Tests and practical reliability were evaluated.

Next, various physical property tests and methods for measuring and evaluating practical reliability will be described. The surface resistance of the metal-containing thin film 6 was measured using a surface resistance meter HT-210 manufactured by Mitsubishi Yuka.

As a method of measuring the amount of the lubricant, F1s (1s orbit of fluorine) spectrum of the lubricant layer 5 on the diamond-like carbon film 4 was analyzed using ESCA-850 manufactured by Shimadzu Corporation, and the sensitivity was corrected. The peak height value was defined as the amount of lubricant. The peak height value analyzed immediately after production was set to 1, and 40 ° C 90% when wound about 10 m on an open reel.
R. H. (Relative Humidity) The peak height value after standing for 1 month in the environment was defined as the lubricant residual rate.

As a method of evaluating the practical reliability using a video tape recorder, the electrostatic noise is measured by using a commercially available H
The i-8 video tape recorder was used to judge by the frequency of output change due to charging during the recording / reproducing test under the environment of 40 ° C. and 5%, and was judged to be acceptable twice or less per hour.

Still durability was measured by measuring the magnetic recording medium 20.
Mounted on a cassette and using a commercially available Hi-8 video tape recorder at 40 ° C. 5% R.S. H. Under the environment, measure the still life immediately after completion with double load, and measure 40
90% R.C. H. After left in the environment for 1 month, the same measurement as that immediately after completion was performed. The still life was judged as a value at the time when the reproduction output was lowered by 3 dB from the initial measurement value.

The method for measuring the head clogging was as follows. The same video tape recorder used for measuring the still durability was used to mount the magnetic recording medium 20 having a length of 60 minutes in a cassette.
23 ° C. 70% R. H. After recording the signal under the environment, 1
The head clogging is defined as the case where the reproduction output decreases by 6 dB or more for a finite time during the reproduction for 00 passes (100 hours), and the total time is displayed in seconds.

Table 1 shows the preparation contents and evaluation results of each sample of Example 1 prepared as described above.

[0063]

[Table 1]

Example 2 In Example 2, after the diamond-like carbon film 4 was formed, the magnetic recording medium 20 was once taken out of the vacuum chamber and sputtered on the back coat layer 3 in another vacuum chamber. Only the point that the metal-containing thin film 6 was formed by the reactive vapor deposition method was different from that of Example 1, and a sample having the metal-containing thin film 6 of the same material and thickness as in Example 1 was prepared. A physical property test and evaluation of practical reliability were performed. Table 2 shows the manufacturing contents and evaluation results of each sample of this Example 2.

[0065]

[Table 2]

(Embodiment 3) FIG. 4 is a schematic view showing another example of the apparatus configuration of the method for manufacturing a magnetic recording medium of the present invention. In the present embodiment, the metal-containing thin film 6 is formed by the plasma CVD method, whereas the first embodiment is different in that it is formed by the sputtering apparatus.

Since the structure and operation of the plasma CVD apparatus of this embodiment are the same as those of Embodiment 1 shown in FIG. 2, only the sample preparation conditions will be described here.

In the second discharge tube 61, the fourth gas introduction port 63
Ferrocene 0.02To as a metal-containing organic compound
Introduced at a pressure of rr, frequency 500k from the fourth power supply 64
The power supply was adjusted in the range of 0.06 kW to 2 kW in Hz, and the metal-containing thin film 6 was formed into 7 samples in the range of 0.008 to 5.5 nm. Further, a sample was prepared in which the metal-containing thin film 6 was formed to a thickness of 1.0 nm by using tetraoctyltin or dibutylmethoxytin as the metal-containing organic compound.

The samples prepared as described above were evaluated for the same physical property tests and practical reliability as in Example 1 above. Table 3 shows the preparation contents and evaluation results of each sample.

[0070]

[Table 3]

Example 4 In this example, after the diamond-like carbon film 4 was formed, the magnetic recording medium 20 was once taken out of the vacuum chamber, and the back coating layer 3 was formed on the back coat layer 3 in another vacuum chamber by the plasma CVD method. A sample in which the metal-containing thin film 6 having the same material and thickness as in Example 3 was formed was prepared by making only the point of forming the metal-containing thin film 6 different from that in Example 3, and the same physical property test as in Example 1 was performed. And the practical reliability was evaluated.

(Comparative Example) In order to compare the effects of Examples 1 to 4, as Comparative Example 1, the diamond-like carbon film 4 and the back coat layer 3 were treated without any treatment. 4, a diamond layer 4 was provided with a lubricant layer 5, and a diamond-like carbon film 4 was prepared as Comparative Example 2.
A sample having a metal-containing plasma polymerized film with a thickness of 1.0 nm formed thereon was prepared, and a sample having a fluorine-containing plasma polymerized film with a thickness of 1.0 nm provided on the back coat layer 3 as Comparative Example 3. It was prepared, and the other processes and evaluations were performed in the same manner.

Table 4 shows the manufacturing contents and evaluation results of the samples of Example 4 and the comparative example.

[0074]

[Table 4]

As can be seen from Tables 1 to 4, the degree of improvement in the electrostatic noise as the practical reliability is obtained in the thick sample having the low surface resistance regardless of the forming method of the metal-containing thin film 6 and the constituent material. Is large, and it does not occur at 1.0 nm or more. In particular, a great improvement effect is recognized with respect to Comparative Example 3 in which the fluorine-containing plasma polymerized film is provided on the back coat layer 3. The reason for this is that the electric charge charged on the back coat layer 3 and the non-magnetic substrate 1 causes the metal-containing thin film 6 having a low surface resistance while the magnetic recording medium 20 in the video tape recorder is running.
It is considered that this is because it is easier to escape from the metal part of the running system of the video tape recorder.

40 ° C. 90% R. H. The still durability after being left in the environment for 1 month is slightly different depending on the method of forming the metal-containing thin film 6 and the range of the film thickness, and is 0.05 to 3.0 nm by the sputtering method and the reactive vapor deposition method. It is effective for the comparative example. The reason for this is that the lubricant and the metal-containing thin film 6 have a strong affinity, so that when the lubricant layer 5 is formed, a certain amount of lubricant is retained on the metal-containing thin film 6 on the back coat layer 3, and a certain amount of lubricant is retained. It is thought to be to stabilize at.

Further, the metal-containing thin film 6 formed by the plasma CVD method
It was found that the forming method of (1) has an improving effect in the film thickness range of 0.01 to 5.0 nm and is effective in a wide range. It is considered that the reason is that the thin film formed by the plasma CVD method is denser and more chemically stable, so that the range in which the movement of the lubricant can be balanced becomes wider.

Therefore, the thickness of the metal-containing thin film 6 is 0.01-.
5.0 nm is preferable, and 0.05 to 3.0 nm is more preferable. The surface resistance of the metal-containing thin film 6 is preferably in the range of 10 ² to 10 ⁸ Ω / □ in view of the balance between electrostatic noise and still durability after being left at high temperature and high humidity.

As for the head clogging, the method of forming the diamond-like carbon film 4 and the metal-containing thin film 6 in the same vacuum chamber in the first and third embodiments is more preferable than that in the second embodiment.
It was found that the method was improved over the method of forming the diamond-like carbon film 4 of Example 4, exposing it once to the atmosphere, and then forming the metal-containing thin film 6 with another vacuum device. The cause is that water in the atmosphere is once adsorbed to the back coat layer 3 when exposed to the atmosphere, the adhesion strength of the metal-containing thin film 6 is reduced, and part of the metal-containing thin film 6 falls off during traveling. Conceivable.

Further, as seen in Comparative Example 2, the still durability is not deteriorated immediately after the production. Still further,
In the first and third embodiments, the feeding roller 21
The same result was obtained when the winding roller 30 was manufactured by a manufacturing apparatus provided outside the vacuum chamber 31.

[0081]

As described above, according to the magnetic recording medium of the present invention, the metal-containing thin film is a lubricant containing a fluorine atom while optimizing the surface resistance of the back coating surface to reduce electrostatic noise. It is possible to hold an appropriate amount of carboxylic acid, and it is also possible to improve still durability in a low humidity environment after being left at high temperature and high humidity. Further, according to the method for producing a magnetic recording medium and the apparatus for producing the same of the present invention, a metal-containing thin film is formed on a back coat layer by a sputtering method, a reactive vapor deposition method or a plasma CVD method. The agent can be uniformly held, and the magnetic recording medium having the above quality can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a magnetic recording medium.

FIG. 2 is a schematic configuration diagram of an apparatus for continuously forming a metal-containing thin film by a sputtering method immediately after forming a diamond-like carbon film by a plasma CVD method in the same vacuum chamber.

FIG. 3 is a schematic configuration diagram of an apparatus for continuously forming a metal-containing thin film by a reactive vapor deposition method immediately after forming a diamond-like carbon film by a plasma CVD method in the same vacuum chamber.

FIG. 4 is a schematic configuration diagram of an apparatus for continuously forming a diamond-like carbon film and a metal-containing thin film by a plasma CVD method in the same vacuum chamber.

[Explanation of symbols]

 1 non-magnetic substrate 2 ferromagnetic metal thin film 3 back coat layer 4 diamond-like carbon film 5 lubricant layer 6 metal-containing thin film 20 magnetic recording medium 21 feeding roller 22, 24-27, 29 path roller 23 first main roller 28 second main Roller 30 Winding roller 31 Vacuum tank 32 Vacuum pump 33 First discharge tube 34 First electrode 35 First gas introduction port 36 First power supply 37 Sputter target 38 Second gas introduction port 39 First deposition plate 40 Second power supply 51 Crucible 52 Evaporation material 53 Third gas inlet 54 Shutter 55 Second deposition plate 56 Third power source 61 Second discharge tube 62 Second electrode 63 Fourth gas inlet 64 Fourth power source

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadayuki Okazaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenji Kuwahara, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co. 72) Inventor Mikio Murai 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yutaka Oda 1006 Kadoma, Kadoma City Osaka Prefecture Matsushita Electric Industrial

Claims (11)

[Claims] 1. A ferromagnetic metal thin film, a diamond-like carbon film, and a lubricant layer are sequentially provided on one surface of a non-magnetic substrate,
A magnetic recording medium, wherein a back coat layer is provided on the other surface, and a thin film containing metal atoms is provided on the back coat layer. 2. The magnetic recording medium according to claim 1, wherein the thin film containing metal atoms is at least one substance selected from metal oxides, metal nitrides, metal carbides, and metal borides. 3. The magnetic recording medium according to claim 1, wherein the thin film containing metal atoms is a metal-containing organic compound. 4. A surface resistance of a thin film containing a metal atom 10 ²
10. The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a resistance of 10 ⁸ Ω / □. 5. The thickness of the thin film containing metal atoms is 0.01 to.
The magnetic recording medium according to claim 1, which has a thickness of 5.0 nm. 6. A ferromagnetic metal thin film is formed on one surface of a non-magnetic substrate, a back coat layer is formed on the other surface, and then diamond-like carbon is formed on the ferromagnetic metal thin film in a vacuum chamber by plasma CVD. A method of manufacturing a magnetic recording medium, which comprises forming a film and then forming a thin film containing metal atoms on the back coat layer. 7. The magnetic recording medium according to claim 6, wherein the thin film containing the metal atoms is continuously formed following the formation of the diamond-like carbon film in the same vacuum chamber as that for forming the diamond-like carbon film. Manufacturing method. 8. The method of manufacturing a magnetic recording medium according to claim 6, wherein the thin film containing metal atoms is formed by a sputtering method or a reactive vapor deposition method. 9. The diamond-like carbon film is formed, and subsequently, a thin film containing metal atoms is continuously formed on the back coat layer by plasma CVD in the same vacuum chamber.
Or a method of manufacturing a magnetic recording medium according to 7. 10. A device for transporting a magnetic recording medium having a ferromagnetic metal thin film formed on one surface of a non-magnetic substrate and a back coat layer formed on the other surface, and a device for transporting the magnetic recording medium on the ferromagnetic metal thin film. A roller for supporting and transporting the magnetic recording medium for forming a diamond-like carbon film by a plasma CVD method, and a plasma CVD apparatus provided with a discharge tube, an electrode and a gas inlet are provided, and A film forming apparatus for forming a thin film containing metal atoms on the back coat layer, a transfer device for transferring the magnetic recording medium to the film forming apparatus, and a magnetic recording medium supporting the magnetic recording medium when forming a thin film containing metal atoms. The transfer roller is arranged in the same vacuum chamber, and the film forming apparatus is a sputtering target, a sputtering apparatus having a gas introduction port, or a crucible, a shutter, a deposition preventive plate, an evaporation material heating apparatus, a gas introduction port. An apparatus for manufacturing a magnetic recording medium, comprising a reactive vapor deposition apparatus comprising: 11. The magnetic recording medium manufacturing apparatus according to claim 10, wherein the film forming apparatus is a plasma CVD apparatus including a discharge tube, an electrode, and a gas inlet.