JPH05135351A - Magnetic recording medium and manufacture thereof and sliding member - Google Patents

Abstract

PURPOSE:To improve the still life and corrosion resistance by providing a lubricant layer consisting of a monomer incorporating a long chain alkyl group on a protective film constituting of a magnetic recording medium or a sliding member and irradiating the lubricant layer by free radicals, atomic gas or electron beams. CONSTITUTION:After a lubricant layer 5 consisting of a ferromagnetic metallic thin film 2, a protective film 4 and monomer is successively formed, a part of the monomer in the lubricant layer 5 is formed a graft polymer as the protective film 4 is a backbone by the free radicals, atomic gas or electron beams. Thus, while the strength of the protective film 4 is maintained without any damage on the protective film 4 by the ions at the graft polymer forming time, the graft polymer can be formed. Hence a reactive group partially separated from the monomer bonds chemically with the protective film 4, so that the lubricant adheres strongly and then clogging of a head of a magnetic recording medium is reduced and the corrosion resistance is greatly improved.

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 and a sliding member, and more particularly to a synergistic effect of a protective film and a lubricant layer provided after the formation of a magnetic layer or on the sliding member substrate for improving practical performance. The present invention relates to a magnetic recording medium that significantly improves practical performance by its effect, a manufacturing method thereof, and a sliding member.

[0002]

2. Description of the Related Art Polymer films such as polyester, polyimide, etc., formed by depositing Co, Ni, Fe or an alloy containing them as a main component in a vacuum such as a vacuum deposition method, a sputtering method and an ion plating method. And a ferromagnetic metal type magnetic recording medium formed on a substrate made of non-magnetic metal,
It is possible to dramatically improve the recording density as compared with the conventional coating type magnetic recording medium. By the way, as a condition for increasing the recording density, it is important to reduce recording / reproducing defects as much as possible and to reduce spacing loss between the magnetic head and the magnetic recording medium as much as possible.

Further, it is necessary for the magnetic recording medium to have durability. Conventionally, there is known a magnetic recording medium in which a protective film and a lubricant layer are provided after forming a magnetic layer in order to satisfy these conditions (for example, JP-A-2-158909). Also, a method of providing an oxide layer and a lubricant layer after forming the protective film (for example, Japanese Patent Laid-Open No. 11382/1993).
5), and a magnetic disk (US Pat. No. 4,960,609) in which a lubricant layer made of fluoroether is formed on a protective film made of carbon and then plasma-treated with an inert gas such as nitrogen. ..

Further, the sliding member is required to maintain wear resistance and low friction characteristics for a long time. In order to satisfy these performances, a magnetic recording / reproducing drum or sliding member provided with a diamond-like carbon film or a hard carbon film as a protective film on a metal substrate (for example, JP-A-2-126456 and JP-A-2-158690). No. gazette) is known.

[0005]

However, in the magnetic recording medium provided with the lubricant layer after the formation of the protective film as the conventional method, the bonding between the protective film and the lubricant becomes insufficient, and the practical performance in a video tape recorder is not improved. The lubricant is scraped off by the head, which causes clogging of the head.
In addition, when a forced oxidation layer is provided on the protective film and a lubricant layer is provided and plasma treatment is performed with an inert gas after the lubricant layer is provided on the protective film, defects such as pinholes occur in the protective film itself due to plasma ion damage. However, the corrosion resistance is reduced.

Further, the method of providing the protective film on the metal substrate improves the wear resistance in a short time, but not only abrades the sliding counterpart, but also increases the friction coefficient, which results in a sliding member. As a result, the wear itself rapidly progresses with the lapse of time, and the function as the sliding member is lost.

In order to solve the above-mentioned problems, the object of the present invention is to strengthen the bond between the protective film and the lubricant layer, to exert the synergistic effect of the protective film and the lubricant, and to prevent head clogging as a practical performance in a video tape recorder. It is an object of the present invention to provide a magnetic recording medium having a significantly reduced corrosion resistance and a significantly improved corrosion resistance, a manufacturing method thereof, and a sliding member capable of maintaining wear resistance and low friction characteristics over a long period of time.

[0008]

In order to solve the above-mentioned problems, a magnetic recording medium and a sliding member of the present invention have a ferromagnetic metal thin film formed on a non-magnetic substrate, and the ferromagnetic metal thin film or the sliding member is formed. A lubricant in which a protective film is formed on a member base, and a monomer containing a long-chain alkyl group and a graft polymer containing a long-chain alkyl group and having the protective film as a trunk are mixed on the protective film. It is characterized in that a layer is provided. Further, the method for producing a magnetic recording medium of the present invention comprises the steps of forming a ferromagnetic metal thin film on a non-magnetic substrate, forming a protective film on the ferromagnetic metal thin film, and sequentially forming a lubricant layer made of a monomer. The graft layer is formed by irradiating the lubricant layer with a free radical or an atomic gas, or an electron beam.

[0009]

According to the present invention, a ferromagnetic metal thin film, a protective film, and a lubricant layer made of a monomer are sequentially formed in a magnetic recording medium, and a protective film is formed on a metal or non-metal substrate in a sliding member. After forming a lubricant layer composed of a monomer, a part of the monomer of the lubricant layer is converted into a graft polymer having a protective film as a trunk by a free radical or an atomic gas or an electron beam, thereby grafting The graft polymer can be formed while maintaining the strength of the protective film without any damage to the protective film by ions during polymer formation. Therefore, the reactive group partially separated from the monomer chemically bonds to the protective film, so that the lubricant is firmly attached.
Further, since the graft polymer protects the monomer, a certain amount of lubricant is always present on the protective film.

Therefore, in the magnetic recording medium, the head clogging is reduced and the corrosion resistance is greatly improved as practical performance when used in a video tape recorder. Further, in the sliding member (for example, a magnetic head, a tape fixing guide for a video tape recorder, and a recording / reproducing drum), abrasion resistance and low friction characteristics can be maintained, and the practical performance is greatly improved.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

(Embodiment 1) (FIG. 1) shows a basic structure of a magnetic recording medium in an embodiment of the present invention. In FIG. 1, a polyester (PET) film having a thickness of 3 to 20 μm is used as the non-magnetic substrate 1, and Co—having a thickness of 0.1 to 0.2 μm is formed on the surface.
This is a magnetic recording medium 20 in which a ferromagnetic metal thin film 2 made of a Ni alloy is formed by oblique vapor deposition, and a back coating layer 3 made of a mixture of resin and carbon or the like is formed on the back surface in order to improve runnability. A protective film 4 is provided on the magnetic metal thin film 2. The protective film 4 is a diamond-like carbon film which is a typical example of an amorphous carbon film and is formed by a mixed gas of argon and a hydrocarbon gas by a plasma CVD method. Further thereon, a lubricant layer 5 made of a monomer containing a long-chain alkyl group and a graft polymer containing a long-chain alkyl group and having the protective film 4 as a trunk is formed.

As a method of forming a part of the monomer of the lubricant layer 5 into a graft polymer having the protective film 4 as a trunk, free radicals or atomic gas generated during plasma discharge is used (claim) An outline of an apparatus configuration of a manufacturing method corresponding to items 1) to 10 is shown in FIG.

In FIG. 2, reference numeral 20a is a magnetic recording medium on which a lubricant layer 5 made of a monomer is formed, which is wound around a feeding roller 21 and is fed under controlled tension.
Reference numerals 22 and 24 denote pass rollers, which come into contact with the magnetic recording medium 20 and rotate. Reference numeral 23 is a main roller, the surface temperature of which is controlled and the rotation of which is controlled so that the magnetic recording medium 20 can be conveyed at a constant speed. Reference numeral 25 denotes a winding roller for continuously winding the magnetic recording medium 20b having the lubricant layer 5 containing the graft polymer, and the tension thereof is controlled similarly to the feeding roller 21.

Reference numeral 26 is a discharge tube, and 27 is a discharge excitation coil, which generates plasma in the discharge tube 26 by a voltage from a power source 30. 28 is a slit for taking out free radicals or atomic gas from the plasma generated in the discharge tube. Reference numeral 29 is a gas inlet for supplying a raw material gas that is a source of free radicals or atomic gas. These, discharge tube 26, excitation coil 27, slit 28, gas inlet 29
The power source 30 constitutes a source of free radicals and atomic gas. It should be noted that the raw material gas was supplied to the gas introduction port 29 in the amount of
It can be introduced at a partial pressure of 5 to 0.0005 Torr. Power supply 3
0 has a maximum frequency of 10k at a frequency of 10kHz to 5GHz.
A voltage of V can be generated. 31 is a vacuum tank, 32 is a vacuum pump.

A method of manufacturing the magnetic recording medium having the above structure will be described with reference to FIG.

First, the vacuum chamber 31 is evacuated by a vacuum pump 32 to reach a specified degree of vacuum (5 × 10 ^-4 Torr), and then the surface temperature of the main roller 23 is controlled to be constant.
Magnetic recording medium 20a having a lubricant layer 5 made of a monomer
Is in close contact with the main roller 23 and is continuously fed from the feeding roller 21 toward the winding roller 25. On the other hand, in the device for generating free radicals and atomic gas, plasma is generated in the discharge tube 26 by the voltage from the power source 30 and the raw material gas from the gas introduction port 29.

In the plasma generated in the discharge tube 26, the pressure of the raw material gas is set as high as 0.1 Torr.
When the ion ratio becomes 20% or less, the ions in the plasma are further cut by the slit 28, and the magnetic recording medium 20
Is reached in the state of free radicals or atomic gases, and by these actions, a part of the protective film 4 and a part of the elements constituting the monomer of the lubricant layer 5 are reached. It chemically bonds to form a graft polymer having a protective film as a trunk. Therefore, a strong bond between the protective film 4 and the lubricant layer 5 can be obtained. In addition, as practical performance in a video tape recorder, head clogging is reduced, and still life and corrosion resistance are improved.

[0019]

[Table 1]

In Table 1, a lubricant layer was formed by the method of (Example 1) using monomers having different numbers of carbons and fluorines, and the power supply, the source gas and its flow rate, the irradiation time and The number of carbon atoms in each graft polymer and the ratio of the graft polymer to the entire lubricant layer 5 are shown for each magnetic recording medium 20 produced by changing the ion ratio and the like.

The number of C in the graft polymer described in (Table 1) is adjusted by the supply power (applied voltage and current) from the power source 30 and the supply amount of the raw material gas for generating free radicals or atomic gas. By doing so, various values can be obtained. In this case, each sample was manufactured by keeping the flow rate of the raw material gas constant and changing the power supply per unit area of the magnetic recording medium 20. The ratio of the graft polymer to the entire lubricant layer 5 can be adjusted to various values by adjusting the time of irradiating the lubricant layer made of a monomer with a free radical or an atomic gas.

Specifically, each sample was manufactured by changing the conveying speed of the magnetic recording medium 20. Next, with respect to the kind of the raw material gas, the experiment was conducted mainly on nitrogen, and the experiment was conducted on the other raw material gas only under the condition that the best result was obtained in the nitrogen. Further, the ratio of ions to free radicals or atomic gas is determined by slit 2
Various values can be obtained by adjusting the slit width and thickness of No. 8. In addition, sample No. of (Table 1). Two
Except for 5, 26, the ion ratio was 7% or less. The ion ratio was measured using a plasma spectroscopy analyzer (MCPD-1000) manufactured by Otsuka Electronics Co., Ltd.

(Example 2) A part of the monomer of the lubricant layer 5 was
As a method for forming a graft polymer having the protective film 4 as a trunk, free radicals or atomic gases generated during corona discharge are used (claim 1) to (claim 9) and (claim 1).
The apparatus configuration of the manufacturing method corresponding to 1) is shown in FIG.

This example differs greatly from Example 1 in that the graft polymer is formed in the atmosphere. In FIG. 3, reference numeral 20a denotes a magnetic recording medium on which the lubricant layer 5 made of a monomer is formed, which is wound around the payout roller 21 in the same manner as in (Example 1), and is magnetized by the main roller 23 and the press roller 33. The recording medium 20 is conveyed at a constant speed,
It is wound by the winding roller 25. Further, 34 is a discharge chamber and 35 is a discharge electrode. Corona discharge is generated between the ground electrode 36 and the voltage from the corona power source 39 and the source gas from the gas purge port 38.

Numeral 37 is a free radical blowing port formed in a slit shape for taking out free radicals and atomic gas generated during corona discharge. The corona power supply 39 can generate a voltage of up to 30 kV at a frequency of 1 to 100 kHz. These, discharge chamber 34, discharge electrode 35, earth electrode 3
6. A processing device for taking out the free radicals and the atomic gas from the corona discharge by the free radical blowing port 37, the gas purging port 38, and the corona power source 39 is formed.

A method of manufacturing the magnetic recording medium having the above structure will be described with reference to FIG.

The magnetic recording medium 20a on which the lubricant layer 5 made of a monomer is formed has a main roller 23 and a press roller 33.
By this, it is controlled to a constant speed and is continuously fed from the feeding roller 21 toward the winding roller 25. On the other hand, in the device for generating free radicals and atomic gas, corona discharge is generated in the discharge chamber 34 by the voltage from the corona power source 39 and the source gas from the gas purge port 38.

Ions, free radicals, and atomic gas generated during this corona discharge are irradiated onto the magnetic recording medium 20 in a state where the ions are cut by the free radical jet 37, and by these actions, the protective film 4 is protected. Part and lubricant layer 5
A part of the elements composing the monomer is chemically bonded to form a graft polymer having a protective film as a trunk. Therefore, a strong bond between the protective film 4 and the lubricant layer 5 can be obtained. In this case, the monomer itself constituting the lubricant layer 5 is irradiated with free radicals or atomic gas in a very stable state in the atmosphere, so that head clogging is greatly reduced.

[0029]

[Table 2]

According to the method of (Example 2) in Table 2, a lubricant layer is formed by using monomers having different numbers of carbons and fluorines, and the power supplied from the corona power source 39 and the source gas are supplied. The number of carbons in each graft polymer and the ratio of the graft polymer to the entire lubricant layer 5 are shown for each magnetic recording medium 20 produced by varying the amount and irradiation time.

The number of C in the graft polymer described in (Table 2) is the power supplied from the corona power source 39 (applied voltage and current).
Various values can be obtained by adjusting the supply amount of the raw material gas for generating free radicals or atomic gas.

In this case, the source gas was used, the flow rate was kept constant, and the power supply was changed. The ratio of the graft polymer to the entire lubricant layer 5 can be adjusted to various values by adjusting the time for irradiating the lubricant layer made of a monomer with electron free radicals or atomic gas. Specifically, the transport speed of the magnetic recording medium 20 was changed. Furthermore, in this case, the ratio of ions to free radicals or atomic gas is 7% or less.

(Example 3) As a method for forming a graft polymer having a part of the monomer of the lubricant layer 5 as the trunk of the protective film 4, an electron beam is used (claim 1) to (claim 6). ), (Claim 12) and (Claim 13), an example of an apparatus configuration of a manufacturing method is shown in FIG.

This example is different from (Example 1) in that the method for forming a graft polymer having the protective film 4 as a trunk uses an electron beam. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and detailed description thereof is omitted.

In FIG. 4, reference numeral 20a denotes a magnetic recording medium on which a lubricant layer 5 made of a monomer is formed. As in (Example 1), the feeding roller 21 is in close contact with the main roller 23 at a constant speed. It is continuously conveyed toward the winding roller 25. Further, 40 is an electron generating filament, and 41 is a device for preventing scattering of electrons generated by the electron beam keeper. A power source 42 for generating an electron beam is capable of generating an electron beam and accelerating toward the magnetic recording medium 20.

The electron beam generating filament 40, the electron beam keeper 41, and the electron beam generating power source 42 constitute an electron beam generator. Further, an inert gas such as Ar can be introduced into the electron beam keeper 41.

A method of manufacturing the magnetic recording medium having the above structure will be described with reference to FIG.

Similar to (Example 1), after reaching a specified vacuum degree, the surface temperature of the main roller 23 is controlled to be constant while the lubricant layer 5 made of a monomer is formed on the magnetic recording medium 2.
0a is conveyed from the feeding roller 21 toward the winding roller 25. On the other hand, in the electron beam generator, the electron beam power source 42 generates and accelerates the electron beam to generate the magnetic recording medium 20.
Reaching a point where a part of the monomer of the protective film 4 or the lubricant layer 5 is separated, and a graft polymer having the protective film 4 as a trunk can be formed. Further, since an electron beam is used, the effect is great when a monomer containing a double bond is used as the lubricant layer 5. In this case, since the protective film 4 and the lubricant layer 5 are less damaged, the corrosion resistance of the magnetic recording medium 20 is further improved.

[0039]

[Table 3]

According to the method of (Example 3) in Table 3, a lubricant layer is formed by using monomers having different numbers of carbons and fluorines, and the power supplied from the electron beam generating power source 42 and the pass roller are used. Magnetic recording medium 2 manufactured by variously changing the accelerating voltage applied to the magnetic recording medium 20 via 24 and the irradiation time.
The number of carbon atoms of each graft polymer and the ratio of the graft polymer to the entire lubricant layer 5 are shown for each 0.

The number of carbon atoms in the graft polymer shown in Table 3 is adjusted by adjusting the power supplied from the electron beam generating power source 42 (applied voltage and current) and the acceleration voltage applied to the magnetic recording medium 20. Can obtain various values. In this case, the electron beam generation power was changed for monomers having different numbers of carbons, and the acceleration voltage was changed for those having the same number of carbons. Further, the ratio of the graft polymer to the entire lubricant layer 5 can be various values by adjusting the time of irradiating the lubricant layer made of a monomer with an electron beam. Specifically, the transport speed of the magnetic recording medium 20 was changed.

(Example 4) In the same vacuum chamber, formation of the lubricant layer 5 made of a monomer and formation of the graft polymer having the protective film 4 as a trunk are continuously carried out by utilizing free radicals or atomic gases. As a processing method, (claim 1) to (claim 9) and (claim 11), (claim 14), (claim 1)
An example of the apparatus configuration in the manufacturing method corresponding to 5) is shown in FIG.

This example differs from (Example 1) in that an apparatus for forming the lubricant layer 5 made of a monomer is provided in the same vacuum chamber. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and detailed description thereof is omitted. In FIG. 5, 20c is a magnetic recording medium in which the lubricant tank 5 made of a monomer is not formed yet, and the feeding roller 21 to the main roller 23 are the same as in (Example 1).
It is transported in close contact with. 43 is a lubricant heating device, 44
Is an evaporation source, 45 is an adhesion preventive plate, 46 is a shutter, and 47 is a lubricant, and these constitute a device for forming the lubricant layer 5 made of a monomer.

A method of manufacturing the magnetic recording medium having the above structure will be described with reference to FIG.

Similar to (Example 1), after reaching the specified vacuum degree, the magnetic recording medium 20c on which the lubricant layer 5 is not yet formed while controlling the temperature of the main roller 23 at a constant temperature is set in the lubricant layer forming region. Transport. In the area where the lubricant layer 5 is formed, the evaporation source 44
The lubricant 47 made of the monomer filled in is heated by the lubricant heating device 43, and the shutter 46 is opened when the prescribed evaporation rate is reached, and the lubricant layer 5 is formed on the protective film of the magnetic recording medium 20c. To be done. Also, the evaporated lubricant particles
A deposition preventive plate 45 is provided to prevent the constituent elements of the device from being contaminated. The magnetic recording medium 20 on which the lubricant layer 5 is formed is further conveyed to the graft polymer forming area,
A graft polymer having the protective film 4 as a trunk is formed in the same manner as in (Example 1). In this case, since the lubricant layer 5 is not exposed to the atmosphere after being formed, the lubricant layer 5 does not adsorb water at all and head clogging is further reduced.

[0046]

[Table 4]

In Table 4, according to the method of Example 4, a lubricant layer was formed by using monomers having the numbers of carbons and fluorines, the results of which were good in Example 1, and a power supply, The ratio of the graft polymer to the entire lubricant layer 5 is shown for each magnetic recording medium 20 manufactured by changing the irradiation time while keeping the raw material gas, its flow rate and the ion ratio constant.

The number of C in the graft polymer described in (Table 4) is adjusted by the supply power (applied voltage and current) from the power source 30 and the supply amount of the raw material gas for generating free radicals or atomic gas. By doing so, various values can be obtained. The ratio of the graft polymer to the entire lubricant layer 5 can be variously adjusted by adjusting the time for irradiating the lubricant layer made of a monomer with electron free radicals or atomic gas. Specifically, a sample was manufactured under the same conditions as those for which good results were obtained in (Example 1). Furthermore, the ratios of ions to free radicals and atomic gases are all described in this case to be 7% or less.

(Example 5) As a method of continuously treating the formation of the lubricant layer 5 made of a monomer and the formation of the graft polymer in the same vacuum chamber using an electron beam (claim 1) (Claim 6) and (Claim 13), (Claim 14), (Claim 16) An example of the device composition in the manufacturing method corresponding to (Claim 16) is shown in (Drawing 6).

This embodiment has a structure in which the lubricant layer 5 forming apparatus of (Example 3) and (Example 4) are combined (FIG. 6).
In addition, the same reference numerals are given to the respective constituent elements, and the detailed description and the operation will not be described. In this case, damage to the protective film 4 and the lubricant layer 5 is small, and since the film is not exposed to the air, head clogging is further reduced.

Further, according to the method of this embodiment, samples were manufactured for the protective films 4 having different Vickers hardnesses.

[0052]

[Table 5]

According to the method of (Example 5) in (Table 5),
In Example 2, a lubricant layer was formed by using monomers having the numbers of carbons and fluorines, the results of which were good, and the electron beam generating power source 4 was used.
2. The magnetic recording medium 20 produced by changing the accelerating voltage applied to the magnetic recording medium 20 through the pass roller 24 and the irradiation time while keeping the supply power from 2 constant, the carbon number of each graft polymer, the lubricant The ratio of graft polymer to the entire layer 5 is shown.

Further, it has been described that the ratio of the graft polymer is constant and the protective film has different Vickers hardness.

The number of carbon atoms in the graft polymer shown in Table 5 is adjusted by adjusting the power supplied from the electron beam generating power source 42 (applied voltage and current) and the acceleration voltage applied to the magnetic recording medium 20. Can obtain various values. Further, the ratio of the graft polymer to the entire lubricant layer 5 can be various values by adjusting the time of irradiating the lubricant layer made of a monomer with an electron beam. Specifically, a sample having good results in (Example 3) was manufactured under the same conditions as in (Example 3).

The method for measuring the number of carbon atoms in the graft polymer described in (Table 1) to (Table 5) corresponding to (Example 1) to (Example 5) was carried out by infrared absorption spectroscopy. It was obtained from. The method of calculating the ratio of the graft polymer to the entire lubricant layer 5 is as follows. The magnetic recording medium 20 is washed with isopropyl alcohol or the like which dissolves the lubricant layer 5 most well, and then the amount of the lubricant remaining on the protective film 4 is calculated. The value was divided by the amount of lubricant before washing. The amount of lubricant was defined by the number of fluorine atoms counted by X-ray photoelectron spectroscopy.
Further, the measurement of the ion ratio was calculated by the ratio of the peak value of the absorption wavelength by plasma spectroscopic analysis.

The specifications of the magnetic recording medium 20 manufactured by the methods of (Example 1) to (Example 5) are as follows: a ferromagnetic metal thin film 2 containing Co as a main component and having a thickness of about 1800Å is provided and protection is performed thereon. As the film 4, as a typical example of an amorphous carbon film, a diamond-like carbon film having a Vickers hardness of about 2300 kg / mm ² and a thickness of about 100 A is used, and a lubricant layer made of various monomers is used. After being provided, the lubricant layer 5 in which the monomer and the graft polymer having the protective film 4 as a trunk are mixed is formed.

(Example 5) Sample No. Nos. 79 to 83 are different in hardness of the diamond-like carbon film.

[0059]

[Table 6]

(Comparative Example 1) for comparison in Table 6
As (Comparative Example 5), a lubricant layer 5 made of a monomer is provided on the protective film 4, and the lubricant used in (Comparative Example 3) as (Comparative Example 6) is forcibly oxidized on the protective film 4. On lubricant layer 5
And (Comparative Example 7) to (Comparative Example 10), the lubricant used in (Comparative Example 3) is provided as the lubricant layer 5, and the plasma treatment is performed. (Comparative Example 7), (Comparative Example 8) and each 50 mW / cm ² and 25 mW / cm ² plasma processing power and 0.1Torr the inert gas pressure, (Comparative Example 9), (Comparative Example 10), the gas pressure To 0.0
5 Torr, processing power of 50 mW / cm ² each
And a sample was prepared at 25 mW / cm ² . At this time, the ferromagnetic metal thin film 2 and the protective film 4 of the magnetic recording medium 20 are exactly the same as in the embodiment.

[0061]

[Table 7]

[0062]

[Table 8]

[0063]

[Table 9]

[0064]

[Table 10]

[0065]

[Table 11]

[0066]

[Table 12]

[0067]

[Table 13]

[0068]

[Table 14]

Tables 7 to 14 show the magnetic recording medium 20 manufactured by the method of the present invention and the comparative example, when the practical performance was evaluated using a video tape recorder, the head clogging, the still life, and the low humidity. The still life and corrosion resistance under the environment are shown.

First, a method of evaluating practical performance will be described.
As a specific method for evaluating the head clogging, the magnetic recording medium 20 cut into a length of about 90 minutes and a width of 8 mm is set to 14 m.
2 heads with a relative speed of 3.8 m / sec, a track pitch of about 20 μm, and a protrusion of 30 μm are run.
A video signal is recorded in a rotating cylinder type video tape recorder with an outer diameter of 40 mm in an environment of 23 ° C and 70%, and head clogging time is 100 hours when reproduced for approximately 200 hours in an environment of 23 ° C and 10%. It is converted to per hit. Here, the head clogging time is defined as the clogging time when the reproduction output reduction of 6 dB or more occurs over a finite time.

Further, the still life was measured by recording in the environment of 23 ° C. and 70% using the above-mentioned video tape recorder.
The magnetic recording medium 2 was measured under an environment of 23 ° C. 70% and 23 ° C. 10% under a load that is about three times that of normal running.
The life was defined as the time when scratches were generated up to the ferromagnetic metal thin film 2 of 0 and the output was completely lost. Furthermore, regarding the evaluation of the corrosion resistance, the magnetic recording medium 20 recorded by the same video tape recorder as that at the time of measuring the still life was left as it was at 40 ° C.
The sample was left in a 90% environment and the still life was measured every week under a load of about twice as much as 23 ° C. and a 10% environment. (Table 7) to (Table 14) show a week. The measured value for each is shown.

Subsequently, regarding the effects of the embodiments described in (Table 7) to (Table 13), the relationship between each embodiment and the limited range described in each claim will be sequentially described.

First, in (Example 1), (Comparative Example 1)-
Compared with (Comparative Example 10), it is clear that head clogging, still life, and corrosion resistance were significantly improved in the same number of carbons and fluorine in the monomer. is there.

The number of carbon atoms contained in the monomer is effective when the number is in the range of 10 to 100. Especially 20-5
The effect is large in the range of about 0.

Even if the number of fluorine contained in the monomer is less than 10% or more than 100% of the number of carbon, head clogging is increased, and the effect of irradiation with free radicals or atomic gas is very small. ..

If the ratio of the graft polymer to the entire lubricant layer 5 is less than 10%, there is almost no effect on the corrosion resistance, and as the ratio increases, the corrosion resistance improves, but an increase in head clogging and a decrease in still life are observed. The limit is about 90%.

The number of carbon atoms in the graft polymer is up to several times the number of carbon atoms in the monomer, and if it is more than that, head clogging increases.

As for the source gas of free radical or atomic gas, hydrogen, oxygen, argon or a source gas containing them is effective, but they have little effect on the corrosion resistance and nitrogen is used. Greatly effective on all items.

Regarding the ratio of ions to free radicals or atomic gas, if it exceeds 20%, not only the corrosion resistance is deteriorated but also the still life is shortened, but if it is 20% or less, there is no problem.

It was confirmed that in Example 2, the effect on the still life and corrosion resistance was smaller than that in Example 1, but the effect on head clogging was particularly large. In this case, considering the corrosion resistance, the ratio of the graft polymer to the entire lubricant layer 5 is somewhat narrower than that of (Example 1) and is about 10 to 80%.

In (Example 3), especially when the number of carbons and fluorines in the monomers of (Example 1) and (Example 2) is about twice, and moreover, there is a double bond, the corrosion resistance is It was confirmed that it was further improved as compared with (Example 1).

It was confirmed that the head clogging is further reduced in (Example 4) and (Example 5) as compared with (Example 1) and (Example 2), respectively.

In addition, the sample No. of (Example 5). 79-
In No. 83, the Vickers hardness of the protective film 4 is 1000 kg /
There is no effect unless it exceeds mm ² , 1000 kg / m
It was confirmed that the effect started to appear when it exceeded m ² .

From the above results, the protective film 4 having a hardness equal to or higher than a certain threshold value is provided, and the lubricant layer made of a monomer containing a long-chain alkyl group is provided thereon, and the monomer and the protective film 4 are provided.
By forming the lubricant layer 5 in which the graft polymer having a skeleton as a backbone is mixed, the protective film 4 and the lubricant layer 5 are strongly bonded by a chemical bond, and not only the head clogging is reduced but also the protective film is formed by the graft polymer. It is considered that No. 4 is protected by the lubricant layer 5, and the synergistic effect of them improves the still life and the corrosion resistance significantly.

Further, as a method for forming a graft polymer,
It is considered that the most effective method is to form a graft polymer by utilizing free radicals or atomic gas or electron beam as a condition that does not damage the protective film 4.

That is, a protective film 4 having a hardness not to be shaved in a short time by sliding on the head, and a long-chain alkyl group that hardly adheres to the head and a monomer containing a fluorine compatible therewith. By providing the lubricant layer 5 in which the graft polymer having an effect on the corrosion resistance is mixed in an appropriate ratio, as a practical performance of the magnetic recording medium 20, head clogging, a still life, and a high-dimensional balance of corrosion resistance are secured. It is thought to be possible.

In the above-mentioned embodiment, the case where a diamond-like carbon film is used as the protective film 4 has been described, but even if a protective film such as silicon dioxide, alumina or silicon nitride is used, the corrosion resistance is almost the same. However, when the head-like clogging is hardly improved, a diamond-like carbon film is used as the protective film 4, which provides the best balance for each performance.

In addition, (Example 1), (Example 3), (Example 4), (Example 5), at positions corresponding to the rollers,
The case where a device for irradiating a free radical, an atomic gas, or an electron beam is arranged has been described, but similar results are obtained in the cases where the roller is not used in each of the examples. When a roller is used, heat loss due to close contact with the roller can be prevented, and cracks can be prevented from occurring in the ferromagnetic metal thin film 2 itself.

(Embodiment 6) (FIG. 7) is a metal-in-gap head (hereinafter referred to as MIG head) corresponding to (Claim 17) to (Claim 23) as an example of the sliding member in the embodiment of the present invention. The basic configuration of (referred to) will be shown.

In FIG. 7, reference numeral 51 denotes a core, which is made of single crystal ferrite or the like. Reference numeral 52 denotes a coil, which is wound into a predetermined number of turns after being assembled into a predetermined structure. Reference numeral 53 is a high magnetic flux density magnetic material (hereinafter referred to as high Bs magnetic material), which is formed by a sputtering method or the like using a material in which several kinds of elements having Co or Fe as a base material are mixed.
Reference numeral 54 is a gap, which is made of an insulating material such as silicon oxide.

Reference numeral 4 is a protective film, which is a diamond-like carbon film which is a typical example of an amorphous carbon film formed by a plasma CVD method or an ionization vapor deposition method using argon and hydrocarbon as raw materials. The protective film 4 is formed after processing the sliding surface of the core 51 with the medium into a predetermined shape.
A lubricant layer 5 is composed of a mixture of a monomer containing a long-chain alkyl group and a graft polymer containing a long-chain alkyl group and having the protective film 4 as a trunk.

Further, (FIG. 8) is an example of a sliding member in the embodiment of the present invention (claim 17) to (claim 23).
The basic configuration of a thin film magnetic head corresponding to is shown.

In FIG. 8, reference numeral 1 is a non-magnetic substrate, which is mainly composed of a ceramic material. 55 is a lower magnetic body, and 56 is a head element together with the coil of the upper magnetic body 52. Reference numeral 57 denotes a protective substrate, which is adhered by an adhesive glass 58 to form a sliding portion with respect to the medium. After the sliding portion is processed into a predetermined shape (FIG. 7), the protective film 4 and the lubricant layer 5 are formed.

[0094]

[Table 15]

In Table 15, for this example, a graft polymer having the protective film 4 as a trunk was formed by the same method as in (Example 1) by irradiating with free radicals or atomic gas in plasma discharge. About MIG head, commercially available M for 8 mm
The measurement results of the output reduction due to the uneven wear of the head after running the P tape for 100 hours in an environment of 10 ° C. and 80% were described.

Sample No. In Nos. 101 to 114, the hardness of the protective film 4 was made constant, and the lubricant layer 5 was formed using monomers having different numbers of carbon and fluorine. In this case, nitrogen gas was used to change the supply power, irradiation time, etc. variously to prepare samples having different graft polymer ratios, and the output reduction was measured. Sample No. For Nos. 115 to 117, samples having the same number of monomers containing carbon and fluorine and the same proportion of the graft polymer were prepared for magnetic heads having different hardnesses of the protective film, and the output reduction was measured.

For comparison, a sample in which the protective film 4 is not provided as (Comparative Example 11), a sample in which only the protective film 4 is provided as (Comparative Example 12), and a protective film 4 and a unit amount as (Comparative Example 13) The same measurement was performed on a sample that was provided with a lubricant layer and was plasma-treated with nitrogen gas.

Next, a method of measuring the output reduction will be described.
Only the magnetic head of the video tape recorder used in (Example 1) to (Example 5) was replaced, and a commercially available 8 mm MP tape was used. With the output of recording / reproducing for about 1 minute set to 0 dB, the MP tape was run for 100 hours in an environment of 10 ° C. and 80% after being initialized so that the highest output was obtained, and then the same MP tape was used. About 1
The ratio to the value of the output when recording and reproducing for a minute was defined as the output decrease. The magnetic head used for measurement has a core width of about 1
00 μm, track width about 20 μm, head protrusion amount about 30 μm, relative speed between tape and head is about 3.8 m
/ Sec. The protective film 4 has a thickness of about 300A, and the lubricant layer 5 has a thickness of about 30A.

As shown in the results of (Table 15), in comparison with (Comparative Example 11), the number of carbon atoms in the monomer is 10 or more, and the number of fluorine atoms is about 10% of the number of carbon atoms. Begin,
The number of carbon is about 20, and the number of fluorine is 50 of the number of carbon.
%, And the ratio of the graft polymer is about 50%, the effect is clear. Also (Comparative Example 12),
(Comparative Example 13) had an even worse result than the one without the protective film.

Further, the hardness of the protective film is 1000 k.
It was also confirmed that the effect was obtained at g / mm ² or more.

Further, the same measurement was carried out for the thin film magnetic head and the laminated magnetic head, and the same result was confirmed. From the above results, in the case of the magnetic head, the number of carbons contained in the monomer is 10 or more, and the number of fluorine is effective from 10% or more of the number of carbons to about the same number.
Considering the overall performance as a magnetic head, especially the head clogging, the number of carbons contained in the monomer is 20 to 1
The range of 00, the number of fluorine is 25% to 100 of the number of carbon
The range of% is more preferable. The ratio of the graft polymer is preferably in the range of 10% to 90% with respect to the entire lubricant layer. Further, the hardness of the protective film is preferably 1000 kg / mm ² or more. Summarizing the above results, magnetic heads, especially MIG heads in which different kinds of materials are exposed on the sliding surface of the medium, stacked heads. For thin-film type heads, materials with different altitudes slide on the media sliding surface, which causes wear compared to low-grade materials, increasing the spacing with the media near the head gap, and making the media sufficiently magnetized during recording. However, the magnetization signal from the medium cannot be read sufficiently during reproduction, resulting in a decrease in output. Therefore, by providing a protective film having a certain hardness or more and providing a lubricant layer that firmly adheres to this protective film, wear resistance and low friction characteristics are maintained for a long time, and a predetermined shape is maintained,
It is considered that the decrease in output is greatly reduced.

Particularly, in the case where only the protective film is provided or the case where the lubricant layer is provided on the protective film and the plasma treatment is performed, when only the protective film having high hardness is used, the friction coefficient is increased or the plasma treatment is performed. It is considered that due to the damage of the protective film, the contact pressure is biased due to the traveling of the medium, so that a part of the wear selectively progresses, the spacing near the gap increases, and the output decrease increases.

(Embodiment 7) (FIG. 9) is a tape fixing for a video tape recorder corresponding to (Claim 17) to (Claim 22) and (Claim 24) as a sliding member in the embodiment of the present invention. The basic structure of the guide is shown below.

In FIG. 9, reference numeral 59 is a metal substrate, which is made of stainless steel or the like. Further, 60 is a sliding medium. Other configurations are the same as those in (Example 6), and the method for producing the protective film and the lubricant layer is exactly the same, and therefore detailed description thereof is omitted.

(Embodiment 8) (FIG. 10) is a sliding member according to an embodiment of the present invention (claim 17) to (claim 2).
2) The basic structure of a recording / reproducing drum for a video tape recorder corresponding to (25) is shown.

In FIG. 10, 61 is a fixed drum base and 62 is a rotating drum base, which are made of hard aluminum alloy or the like. Other configurations and manufacturing methods are the same as those in (Example 6), and detailed description thereof will be omitted.

[0107]

[Table 16]

As (Example 7) and (Example 8) in Table 16, a protective film and a lubricant layer made of a monomer are provided in the same manner as in (Example 6), and the protective film is formed by the same method. The rate of increase in the coefficient of friction was described for the sample with the greatest effect of forming a graft polymer as the trunk. For comparison (Comparative Example 14), (Comparative Example 17), a sample not provided with a protective film, (Comparative Example 15), (Comparative Example 18), a sample provided with only a protective film, (Comparative Example 16), As (Comparative Example 19), the same description was made for a sample in which a lubricant layer was provided on a protective film and plasma-treated.

The method of measuring the friction coefficient is as follows:
This was taken as the initial value, based on the coefficient of friction in the state in which was not slid at all. Sliding medium 60 used at this time
Is a commercially available MP tape for 8 mm. The measurement conditions are approximated to the actual running conditions of the video tape recorder, the load is 10 gf, and the running speed of the sliding medium is about 15 mm / sec.
And The tape fixing guide and the recording / reproducing drum whose initial values had been measured were attached to a video tape recorder, and the commercially available 8 mm MP tape was run (slipped) for 1000 hours. Is measured
The ratio with the initial value is shown.

From the results shown in Table 16, it is clear that the ratio of the friction coefficient to the initial value is significantly smaller than that of each comparative example, that is, the increase in the friction coefficient is small.

The reason for this is as follows.
Since it is considered to be almost the same as (Example 6), detailed description will be omitted.

In addition, in (Example 6) to (Example 8),
As a method of forming a graft polymer having a protective film as a trunk after forming a lubricant layer made of a monomer, only a sample prepared by irradiating a free radical or atomic gas in plasma discharge was explained, Similar to the magnetic recording media of Examples 1) to (Example 5), a method of irradiating a free radical or an atomic gas in a corona discharge, an electron beam, a lubricant layer made of a monomer in the same vacuum chamber, and protection. It was confirmed that the same effect can be obtained by adjusting the respective production conditions in the method of continuously forming the graft polymer having the membrane as the trunk.

Finally, the effects of the embodiment will be described in comparison with a method of plasma treatment after forming the lubricant layer.

After the formation of the lubricant layer, the plasma treatment was carried out (Comparative Example 7) to (Comparative Example 10). As shown by the results, the particles were protected by collision with charged particles centering on the ions during the plasma treatment. Defects such as pinholes occur in the film itself, especially when left at high temperature and high humidity, moisture penetrates from the defect part, which causes rust in the ferromagnetic metal thin film, and the adhesion strength between the ferromagnetic metal thin film and the protective film. And the still life is reduced.

In the method of forming a lubricant layer on the protective film of the present invention and then irradiating it with a free radical or an atomic gas, plasma is generated in a low vacuum (10 ^-1 to 10 ^-2 Torr), so that charged particles are mixed with each other. Collide with each other and lose the charge, and most of the neutral free radicals or atomic gases remain in the discharge tube, and these are in a high vacuum region (10 ^{-4 -10 -6} Torr) from the slit provided at the tip during discharge. Jumps out and reaches the magnetic recording medium or sliding member according to the mean free path,
A graft polymer having a protective film as a trunk is formed. Therefore, since the charged particles hardly reach the magnetic recording medium or the sliding member directly, the damage to the protective film is very small,
Since the lubricant itself also adheres strongly to the protective film, it is particularly resistant to corrosion in magnetic recording media and wear resistant to sliding members.
Low friction characteristics are improved.

In the method of irradiating with an electron beam, the electrons themselves are charged particles, but since the mass is at least 1 / 10,000 or less of the atomic gas of nitrogen, the action of charged particles and low damage are extremely compatible. It is a method of forming a graft polymer having an effective protective film as a trunk.

[0117]

As described above, according to the present invention, a lubricant layer composed of a monomer containing a long-chain alkyl group is provided on a protective film constituting a magnetic recording medium or a sliding member, and free radicals or atomic groups are provided. By irradiating the lubricant layer with a gas or an electron beam, it is possible to form a lubricant layer in which the monomer and the graft polymer having the protective film as a trunk are mixed. Therefore, the protective film and the lubricant layer are chemically bonded, and in the magnetic recording medium, as a practical performance in a video tape recorder, head clogging is significantly reduced and still life and corrosion resistance are further improved. Further, in the sliding member, the wear resistance and the low friction property can be maintained for a long time, and the practical reliability is greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a magnetic recording medium.

FIG. 2 is a schematic diagram of an apparatus configuration corresponding to a production method using free radicals or atomic gas in plasma discharge as a method for forming a graft polymer.

FIG. 3 is a schematic diagram of an apparatus configuration corresponding to a production method using free radicals or atomic gas in corona discharge as a method for forming a graft polymer.

FIG. 4 is a schematic diagram of an apparatus configuration corresponding to a manufacturing method using an electron beam as a method for forming a graft polymer.

FIG. 5 shows a method for continuously forming a lubricant layer made of a monomer and a graft polymer in the same vacuum chamber.
Schematic diagram of the apparatus configuration corresponding to the manufacturing method using free radicals or atomic gas in plasma discharge

FIG. 6 shows a method for continuously forming a lubricant layer made of a monomer and a graft polymer in the same vacuum chamber.
Schematic diagram of the device configuration corresponding to the manufacturing method using an electron beam

FIG. 7 is a sectional view showing the basic configuration of an MIG head.

FIG. 8 is a sectional view showing the basic structure of a thin film magnetic head.

FIG. 9 is a cross-sectional view showing the basic configuration of a tape fixing guide for a video tape recorder.

FIG. 10 is a sectional view showing the basic structure of a recording / reproducing drum for a video tape recorder.

[Explanation of symbols]

 1 Non-Magnetic Substrate 2 Ferromagnetic Metal Thin Film 3 Back Coating Layer 4 Protective Film 5 Lubricant Layer 20 Magnetic Recording Medium 21 Feeding Roller 22, 24 Pass Roller 23 Main Roller 25 Winding Roller 26 Discharge Tube 27 Excitation Coil 28 Slit 29 Gas Inlet 30 Power source 31 Vacuum tank 32 Vacuum pump 33 Press roller 34 Discharge chamber 35 Discharge electrode 36 Earth electrode 37 Free radical outlet 38 Gas purge port 39 Corona power source 40 Electron beam generating filament 41 Electron beam keeper 42 Electron beam generating power source 43 Lubricant heating device 44 evaporation source 45 anti-sticking plate 46 shutter 47 lubricant 51 core 52 coil 53 high Bs magnetic body 54 gap 55 upper magnetic body 56 lower magnetic body 57 protective substrate 58 adhesive glass 59 metal base 60 sliding medium 61 fixed drum base 62 Rolling drum base

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Ueda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (25)

[Claims] 1. A ferromagnetic metal thin film is formed on a non-magnetic substrate,
A protective film is formed on the ferromagnetic metal thin film, and a monomer containing a long-chain alkyl group and a graft polymer having a long-chain alkyl group as a backbone are mixed on the protective film. A magnetic recording medium provided with a lubricant layer. 2. The magnetic recording medium according to claim 1, wherein the protective film is an amorphous carbon film. 3. The Vickers hardness of the protective film is 1000 kg /
The magnetic recording medium according to claim 1, wherein the magnetic recording medium has a size of ² mm ² or more. 4. The monomer is 10 to 100% of the carbon number.
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium contains fluorine. 5. The magnetic recording medium according to claim 1, wherein the graft polymer having a protective film as a trunk contains fluorine having 10 to 100% of carbon atoms. 6. The magnetic recording medium according to claim 1, wherein the ratio of the graft polymer to the entire lubricant layer is 10 to 90%. 7. A ferromagnetic metal thin film is formed on a non-magnetic substrate,
A protective film is formed on the ferromagnetic metal thin film, a lubricant layer made of a monomer is sequentially formed, and then a free radical or atomic gas is irradiated to the lubricant layer to form a graft polymer. And a method for manufacturing a magnetic recording medium. 8. A free radical or atomic gas for irradiating the lubricant layer is a single element selected from hydrogen, oxygen and nitrogen, or a material gas containing at least one of them.
8. The method of manufacturing a magnetic recording medium according to claim 7, wherein the magnetic recording medium is produced from an inert gas or the like. 9. The method for producing a magnetic recording medium according to claim 7, wherein the amount of ions irradiated is 7% or less with respect to the free radicals and the atomic gas with which the lubricant layer is irradiated. 10. The method for producing a magnetic recording medium according to claim 9, wherein free radicals or atomic gases generated in plasma are used as a source of free radicals or atomic gases. 11. The method for producing a magnetic recording medium according to claim 9, wherein free radicals or atomic gases generated during corona discharge are used as a source of free radicals or atomic gases. 12. A ferromagnetic metal thin film is formed on a non-magnetic substrate, a protective film is formed on the ferromagnetic metal thin film, and a lubricant layer made of a monomer is sequentially formed, and then an electron beam is applied to the lubricant layer. A method for producing a magnetic recording medium, characterized in that a graft polymer is formed by irradiating the magnetic recording medium. 13. The method for producing a magnetic recording medium according to claim 12, wherein a lubricant made of a monomer having multiple bonds is used. 14. A ferromagnetic metal thin film is provided on a non-magnetic substrate,
After forming a protective film on the ferromagnetic metal thin film, a lubricant layer made of a monomer and a graft copolymer are continuously treated in the same vacuum chamber. Production method. 15. The method for producing a magnetic recording medium according to claim 14, wherein free radicals or atomic gases generated in plasma are used as the method for forming the graft polymer. 16. The method for producing a magnetic recording medium according to claim 14, wherein the graft polymer is formed by irradiating an electron beam. 17. A graft layer comprising a protective film formed on a metal or non-metal substrate, a monomer containing a long-chain alkyl group on the protective film, and a graft film having a long-chain alkyl group as a trunk. A sliding member provided with a lubricant layer mixed with a united body. 18. The sliding member according to claim 17, wherein the protective film is an amorphous carbon film. 19. The Vickers hardness of the protective film is 1000 kg.
/ Mm ² or more, the sliding member according to claim 17. 20. The monomer has 10 to 100 carbon atoms.
18. The sliding member according to claim 17, wherein the sliding member contains% fluorine. 21. The sliding member according to claim 17, wherein the graft polymer having a protective film as a trunk contains fluorine having 10 to 100% of the number of carbon atoms. 22. The sliding member according to claim 17, wherein the ratio of the graft polymer to the entire lubricant layer is 10 to 90%. 23. The metal or non-metal substrate is a magnetic head, as set forth in claim 17, 18, 19, 20.
23. The sliding member according to either 21 or 22. 24. The sliding member according to claim 17, wherein the metal or non-metal substrate is a fixed guide for a video tape recorder. 25. The sliding member according to claim 17, wherein the metal or non-metal substrate is a recording / reproducing drum for a video tape recorder.