JPH05143975A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent traveling property, wear resistance and durability by forming a magnetic layer and a carbon protective film on a nonmagnetic supporting body and then applying a lubricant comprising a perfluoropolyether amine having carboxyl groups at both ends or one end of the molecule expressed by specified formula. CONSTITUTION:On a nonmagnetic supporting body, a magnetic layer and a carbon protective film are successively formed. Then, a perfluoropolyether amine chloride expressed by formula I or II having carboxyl groups at both ends or one end of the molecule is applied as a lubricant. In formulae I and II, Rf is a chain of perfluoropolyether. R<1>, R<2>, R<3> and R<4> are hydrogen or hydrocarbon groups. Durability of the medium is largely improved even when the carbon film is made thin, however, deterioration of characteristics after repetition of traveling can not be prevented. By the interaction of the lubricant above described and the carbon film, excellent durability under various use conditions can be maintained and traveling property can be significantly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape and a magnetic disk, and more particularly to improvement of a lubricant exhibiting an excellent lubricating effect.

[0002]

2. Description of the Related Art For example, in a so-called metal thin film type magnetic recording medium in which a ferromagnetic metal material is deposited on a non-magnetic support by a technique such as vapor deposition and the magnetic layer is used as a magnetic layer, the surface of the magnetic layer is not smooth. Since it is extremely good, the substantial contact area with sliding members such as magnetic heads and guide rollers is large, so the friction coefficient is large and the adhesion phenomenon (so-called sticking) is likely to occur and running performance and durability are poor. There are many problems.

Therefore, use of various kinds of lubricants has been studied in order to improve these problems, and friction has been hitherto caused by top-coating a higher fatty acid or ester thereof on the magnetic layer of the magnetic recording medium. Attempts have been made to reduce the coefficient. By the way, the lubricant used for the magnetic recording medium is required to have extremely strict characteristics, and it is difficult to cope with the conventional lubricant.

That is, the lubricant used in the magnetic recording medium is (1) excellent in low temperature characteristics so as to ensure a predetermined lubricating effect when used in a cold region, and (2) a lubricant with a magnetic head. Since pacing becomes a problem, it is necessary to apply it extremely thinly, to exhibit sufficient lubrication characteristics even in that case, and (3) to endure long-term use or long-term use and maintain the lubrication effect. To be done.

However, conventionally used higher fatty acids and esters thereof are frozen and solidified under low temperature conditions such as 0 ° C. or lower, impairing the function as a lubricant, and long-term durability. Tend to lack.

[0006]

As described above, in the field of magnetic recording media, the lack of ability of the lubricant to be used leaves the practicality unsatisfactory in terms of running property and durability. .. Accordingly, the present invention provides a magnetic recording medium that maintains excellent lubricity under various conditions of use, has a long-lasting lubrication effect, and has excellent runnability, wear resistance, durability, and the like. It is intended.

[0007]

DISCLOSURE OF THE INVENTION In the present invention, as a result of earnest studies that cannot achieve the above-mentioned object, a carbon film is formed on the surface of a magnetic layer and a perfluoro group having a carboxyl group at the end is formed. The inventors have found that an excellent lubricating effect can be obtained by using an amine salt compound of polyether as a lubricant, and have completed the present invention.

That is, the present invention is a magnetic recording medium having at least a magnetic layer on a non-magnetic support, in which a carbon film is formed on the surface of the magnetic layer, and is represented by the following chemical formula 1. The present invention is characterized in that an amine salt compound of perfluoropolyether having carboxyl groups at both ends is retained as a lubricant. The present invention also provides a magnetic recording medium having at least a magnetic layer on a non-magnetic support, in which a carbon film is formed on the surface of the magnetic layer, and at least one of the following Chemical Formula 2 The present invention is characterized in that an amine salt compound of perfluoropolyether having a carboxyl group at the terminal is retained as a lubricant.

In the magnetic recording medium of the present invention, a magnetic layer and a protective film made of a carbon film are sequentially laminated on a non-magnetic support, and a perfluoropolycarbon having a carboxyl group at the end is used as a lubricant. Perfluoropolyether derivatives which are amine salt compounds of ethers are used.

When only the carbon film is formed on the surface of the magnetic layer, the durability can be greatly improved even if the carbon film is very thin, but the output characteristics are deteriorated after repeated running. I can't hold back. On the other hand, in the present invention, with the formation of this carbon film,
Characterized by using the above-mentioned perfluoropolyether derivative as a lubricant, the running property is remarkably improved while ensuring excellent durability under various usage conditions by the interaction between the carbon film and the perfluoropolyether derivative. Can be made

The above perfluoropolyether derivative is
It is a novel compound, and has the characteristics that it exhibits significantly better lubricity than the compounds that have been used as lubricants and that the lubricity is maintained for a long time.
Further, this perfluoropolyether derivative exhibits excellent lubricity even when used under severe conditions such as low temperature and low humidity or high temperature and high humidity, and becomes a very useful compound as a lubricant. Therefore, if this perfluoropolyether derivative is used as a lubricant for magnetic recording media,
Due to the excellent lubrication effect, the friction coefficient is reduced, and the running property, wear resistance, durability, etc. can be greatly improved. Further, since the perfluoropolyether derivative is dissolved in a solvent other than CFC (for example, ethanol), it is very advantageous in production.

This perfluoropolyether derivative is
It is a compound of a perfluoropolyether having a carboxyl group at the terminal and an amine. The perfluoropolyether having a carboxyl group at the terminal may have a carboxyl group at both terminals, or may have a carboxyl group at at least one terminal (one terminal), and is used regardless of its substitution position. be able to.

Among these perfluoropolyether derivatives, compounds of perfluoropolyether having carboxyl groups at both ends (hereinafter referred to as polyfunctional perfluoropolyether) and amine are represented by the following chemical formula 3. It is represented by a formula. A compound of a perfluoropolyether having a carboxyl group only at one end (hereinafter referred to as a monofunctional perfluoropolyether) and an amine is represented by the following general formula.

[0014]

[Chemical 3]

[0015]

[Chemical 4]

Any commercially available perfluoropolyether having a carboxyl group at the terminal can be used. For example, as the monofunctional perfluoropolyether, (a) F (CF ₂ CF ₂ CF ₂ O) _m CF ₂ CF ₂ COOH (b) CF ₃ [OCF (CF ₃ ) CF ₂ ] _j (OCF ₂ ) _k COOH and the like.

Examples of the above polyfunctional perfluoropolyether include (c) HOOCCF ₂ (OCF ₂ CF ₂ ) _p (OCF ₂ ) _q OCF ₂ COOH, but are not limited to these. .. In the chemical structural formula of the perfluoropolyether, m, j, k, p and q each represent an integer of 1 or more.

The molecular weight of the perfluoropolyether having a carboxyl group at the terminal thereof is not particularly limited, but practically about 600 to 5,000 is preferable, and 1,000 to 4,000 is more preferable.
When the molecular weight of perfluoropolyether becomes too large, the effect of the terminal group becomes small and the effect as an adsorbing group becomes weak. Further, it becomes difficult to dissolve in a solvent other than CFC, for example, a general-purpose solvent such as ethanol. On the other hand, if the molecular weight of perfluoropolyether is too small, the lubricating effect of the perfluoropolyether chain will be lost.

On the other hand, as the amine, a primary amine,
Both secondary amines and tertiary amines can be used, and quaternary ammonium compounds can also be used. The structure of the amine used is also arbitrary, and can be arbitrarily selected regardless of the branched structure, isomer structure, alicyclic structure, molecular weight, presence or absence of unsaturated bond, and the like. However, the amine preferably has an alkyl group, and particularly when the amine has an alkyl group having 6 or more carbon atoms, more preferably 10 or more carbon atoms, the effect is large.

In any of the above-mentioned perfluoropolyether derivatives, the perfluoropolyether chain may be partially hydrogenated. That is, some (50% or less) of the fluorine atoms in the perfluoropolyether chain may be replaced with hydrogen atoms. In this case, a partially hydrogenated perfluoropolyether may be used as the perfluoropolyether, which makes it possible to reduce the amount of fluorocarbon solvent used. An example of the structure of the partially hydrogenated perfluoropolyether is shown below, but the structure is not limited to this. (D) F (CF ₂ CF ₂ CF ₂ O) _a (CFHCF ₂ CF ₂ ) _b (CH ₂ CF ₂ CF ₂ O) _c
CF ₂ CF ₂ COOH (However, a, b, and c are integers of 1 or more.)

The perfluoropolyether derivative preferably has a molecular weight of 1400 to 4500.
When the molecular weight of the perfluoropolyether derivative is smaller than the above range, or conversely, when it is large, the friction coefficient cannot be sufficiently reduced, and good running properties and durability cannot be obtained, and magnetic recording The deterioration of the output characteristics becomes remarkable after the medium is repeatedly run.

Further, in this perfluoropolyether derivative, it is desirable that the molecular weight of the polar group portion represented by the following chemical formula 5 is 120 or less. When the molecular weight of the polar group portion is larger than 120, the interaction with the carbon film is weakened due to the steric hindrance of the hydrocarbon group contained in the polar group portion, and the effect as the adsorption group is reduced.

[0023]

[Chemical 5]

Such a perfluoropolyether derivative can be easily synthesized from the above-mentioned perfluoropolyether having a carboxyl group and an amine by the following method. That is, the above monofunctional perfluoropolyether (or polyfunctional perfluoropolyether)
It is possible to synthesize by mixing the amine with an amine and heating at a temperature above the melting point of the amine used (for example, 60 ° C. when stearylamine is used as the amine).

Alternatively, it can also be obtained by dissolving both the monofunctional perfluoropolyether (or polyfunctional perfluoropolyether) and the amine in an organic solvent (for example, Freon) and then removing the solvent. it can.
When the amine is a quaternary ammonium compound, a metal salt of perfluoropolyether (sodium salt, etc.) and a quaternary ammonium salt (chloride, iodide, sulfate, etc.) are mixed,
It can be obtained by extraction with an organic solvent.

Here, as the magnetic recording medium to which the present invention is applied, first, a magnetic coating film is formed as a magnetic layer by coating a magnetic coating on a non-magnetic support, so-called coating type magnetic recording. The medium may be mentioned. In the coating type magnetic recording medium, as the magnetic powder, resin binder, etc. constituting the non-magnetic support or the magnetic coating film, any of those known so far can be used without any limitation.

For example, as the non-magnetic support,
Polyesters, polyolefins, cellulose derivatives, vinyl resins, polyimides, polyamides, polymer supports formed of plastic materials typified by polycarbonate, aluminum alloys, metal substrates made of titanium alloys, etc., The ceramic substrate and glass substrate are made of alumina glass or the like. The shape is not limited at all, and may be any shape such as a tape shape, a sheet shape, and a drum shape. Furthermore, in order to control the surface property of the non-magnetic support,
Fine irregularities may be formed.

[0028] As the magnetic powder, γ-Fe ₂ O _3, ferromagnetic iron oxide particles such as cobalt coating γ-Fe ₂ O _3, ferromagnetic chromium dioxide based particles, Fe, Co, Ni and the like and these Examples thereof include ferromagnetic metal-based particles made of an alloy containing Fe, and hexagonal plate-shaped hexagonal ferrite fine particles. As the resin binder, vinyl chloride, vinyl acetate, vinyl alcohol, vinylidene chloride, acrylic acid ester, methacrylic acid ester, styrene, butadiene, acrylonitrile, or other polymers, or copolymers combining two or more of these, Examples thereof include polyurethane resin, polyester resin, epoxy resin, and cellulose derivative. A hydrophilic polar group such as a carboxyl group, a sulfonic acid group, a sulfuric acid ester group or a phosphoric acid ester group may be introduced into these binders in order to improve the dispersibility of the magnetic powder.

The present invention is also applicable to a so-called metal thin film type magnetic recording medium in which a continuous film of a ferromagnetic metal is formed as a magnetic layer on a non-magnetic support by a method such as vapor deposition and sputtering. Is possible. Of course, in the applied metal thin film type magnetic recording medium, the film structure and the like are arbitrary, and for example, a structure may be such that an underlayer is interposed between the non-magnetic support and the magnetic layer. A back coat layer may be formed on the surface opposite to the surface.

In this metal thin film type magnetic recording medium, the materials of the non-magnetic support, the metal magnetic thin film and the like are not limited in any way, and any conventionally known one can be used.

For example, as the non-magnetic support, the same one as the above-mentioned coating type magnetic recording medium can be used. At this time, when a rigid substrate such as an Al alloy plate or a glass plate is used as the non-magnetic support, an oxide film such as an alumite treatment or a Ni-P film is formed on the surface of the substrate to harden the surface. You may do so.

The metal magnetic thin film is formed as a continuous film by a PVD method such as plating, sputtering or vacuum deposition, and is made of a metal such as Fe, Co or Ni, or Co-Ni.
Alloys, Co-Pt alloys, Co-Pt-Ni alloys,
Fe-Co based alloy, Fe-Ni based alloy, Fe-Co-N
Examples are in-plane magnetization recording metal magnetic films and Co-Cr alloy thin films made of i-based alloys, Fe-Ni-B-based alloys, Fe-Co-B-based alloys, Fe-Co-Ni-B-based alloys, and the like. .

In particular, in the case of an in-plane magnetization recording metal magnetic thin film,
Bi-Sb, Pb, Sn, Ga, on the non-magnetic support in advance
An underlayer of a low-melting point non-magnetic material such as In, Ge, Si, Ti is formed in advance, and a magnetic metal material is vapor-deposited or sputtered from the vertical direction to diffuse the low-melting point non-magnetic material in the metal magnetic thin film. The orientation may be eliminated to secure the in-plane isotropic property, and the anti-magnetism may be improved.

In such a magnetic recording medium, sputtering is generally used as a method for forming a protective film made of a carbon film on the surface of the magnetic layer, but it is not particularly limited, and any method can be used. Is. In this case, the thickness of the carbon film is preferably 5 to 100 nm, more preferably 5 to 30 nm.

When the present invention is applied to a coating type magnetic recording medium as a method for retaining the perfluoropolyether derivative in the magnetic recording medium, the perfluoropolyether derivative is coated with a magnetic paint. Examples thereof include a method of internally adding to the magnetic layer formed as a film, a method of topcoating the surface of the magnetic layer or the surface of the protective film, or a method of using both of them together.

At this time, the amount of the perfluoropolyether derivative used is arbitrary, but when it is internally added to the magnetic layer, for example, it is 0.2 to 2 per 100 parts by weight of the resin binder.
It is preferably 0 part by weight. When topcoating the surface of the magnetic layer or the surface of the protective film, the coating amount is 0.5 to
It is preferably 100 mg / m ^2, and 1 to ²⁰ mg / m ^2.
More preferably, it is m ² .

As a method of retaining the above-mentioned perfluoropolyether derivative in the metal thin film type magnetic recording medium, there is a method of top-coating the surface of the metal magnetic thin film or the surface of the protective film. The coating amount of the polyether derivative is the same as in the case of the above coating type magnetic recording medium. Further, when the above-mentioned magnetic recording medium has a back coat layer, the perfluoropolyether derivative may be internally added as a lubricant into the back coat layer, or may be retained by a top coat. It may be internally added or top-coated both in the film (or in the metal magnetic thin film) and in the back coat layer, and various combinations are possible.

When the perfluoropolyether derivative is thus used as the lubricant, the one synthesized in advance by the above-mentioned method is not used, but the one obtained by adding and mixing the amine to the perfluoropolyether is used as the lubricant. You can also When the amine is added to and mixed with the perfluoropolyether as described above, the above-mentioned perfluoropolyether derivative is produced and the lubricating effect is exhibited.

Here, the mixing ratio of perfluoropolyether and amine may be set so that the carboxyl group and amine (amino group) constituting the polar group portion of the perfluoropolyether derivative are equimolar. However, particularly when it is used as a lubricant for a magnetic recording medium, an excellent lubricating effect is exhibited by setting the ratio such that the amine is slightly in excess. This is because when the lubricant is applied on the magnetic layer, perfluoropolyether, which shows acidity due to a carboxyl group, is preferentially adsorbed on the surface of the ferromagnetic metal thin film (magnetic layer) which is basic, and the amount of amine. It is thought that this is due to the lack of.

Therefore, when the perfluoropolyether derivative is used as a lubricant for a magnetic recording medium, the molar ratio of the carboxyl group to the amine (amino group) (amine / carboxyl group) is 3/7 to 40/1. It is good to

The above perfluoropolyether derivative may be used alone as a lubricant, or may be used in combination with a conventionally known lubricant or the like. Further, in the present invention, an extreme pressure agent may be used in combination at a weight ratio of about 30:70 to 70:30 in order to cope with more severe conditions and maintain the lubricating effect.

The above extreme pressure agent reacts with the metal surface by frictional heat generated when a metal contact is partially generated in the boundary lubrication region, and forms a reaction product film to prevent friction and wear. Any of a phosphorus-based extreme pressure agent, a sulfur-based extreme pressure agent, a halogen-based extreme pressure agent, an organic metal-based extreme pressure agent, a complex-based extreme pressure agent, etc. can be used.

Further, in the present invention, in addition to the above lubricant and extreme pressure agent, a rust preventive agent may be used in combination, if necessary. As the rust preventive, any rust preventive commonly used as a rust preventive for magnetic recording media of this type can be used, and examples thereof include phenols, naphthols, quinones, nitrogen atom-containing heterocyclic compounds, and oxygen atoms. And a heterocyclic compound containing a sulfur atom.

[0044]

The amine salt compound (perfluoropolyether derivative) of perfluoropolyether having a carboxyl group at both ends or one end exhibits a good lubricating action to reduce the friction coefficient. Further, the lubricating action of this perfluoropolyether derivative is not impaired even under severe conditions such as low temperature and low humidity.

Therefore, by forming a carbon film on the surface of the magnetic layer and using such a perfluoropolyether derivative as a lubricant, good durability is ensured and the running property is improved by the excellent lubricating effect. ..

[0046]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples. First, regarding the vapor deposition tape in which a lubricant layer is formed on the carbon film formed on the surface of the magnetic layer by using the perfluoropolyether derivative shown in the following Chemical formula 6 or Chemical formula 7, durability under various use conditions , The runnability was examined.

[0047]

[Chemical 6]

[0048]

[Chemical 7]

Experiment 1 First, a magnetic recording medium was prepared as follows using 14 kinds of perfluoropolyether derivatives (compounds 1 to 14). The type of main chain (perfluoropolyether chain having a carboxyl group at the terminal) constituting the perfluoropolyether derivative (compounds 1 to 14) used in this experiment and the hydrocarbon group contained in the polar group part (Or hydrogen group) and molecular weight are as shown in Tables 1 and 2 below.

[0050]

[Table 1]

[0051]

[Table 2]

That is, Co was deposited on the surface of a 14 μm thick polyethylene terephthalate film by the oblique evaporation method to form a ferromagnetic metal thin film having a film thickness of 200 nm. Then, a protective film made of a carbon film was formed on the surface of the metal magnetic thin film by sputtering so as to have a film thickness of 20 nm. Then, each of the compounds 1 to 14 dissolved in a mixed solvent of freon and ethanol was applied onto the protective film so as to have a coating amount of 5 mg / m ² to form a lubricant layer, and then the magnetic tape was applied. The sample tapes 1 to 14 were obtained by cutting into 8 mm width.

With respect to each of the sample tapes 1 to 14 thus prepared, the friction coefficient and the still durability under the conditions of temperature 25 ° C. and humidity 60%, temperature −5 ° C. and temperature 40 ° C. and humidity 80%. And shuttle durability were measured. The results are shown in Tables 4 and 5.

For comparison, a magnetic tape on which a carbon film was formed and which did not have a lubricant (Comparative Example 1), a perfluoropolyether having a carboxyl group at the terminal shown in Table 3 below as a lubricant, The same measurement was carried out for magnetic tapes (Comparative Examples 2 to 5) each using a perfluoropolyether having a hydroxyl group at the terminal, and magnetic tapes (Comparative Example 6) in which no carbon film was formed and only a lubricant layer was formed. The results are shown in Table 6.

[0055]

[Table 3]

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

In Tables 4 to 6, the still durability represents the time required for the output to decrease by -3 dB in the pause state. The shuttle durability represents the number of shuttles until the output drops by 3 dB when the shuttle travels for 2 minutes each time.

As is clear from Tables 4 to 6, a carboxyl group is added to the terminal as in this example, as compared with the case where a perfluoropolyether having a carboxyl group or a hydrogen group at the terminal is used alone as a lubricant. When the amine salt compound of perfluoropolyether was used, the friction coefficient was low, and good running property and durability were obtained.

Further, from the comparison between each of the sample tapes 1 to 14 and the comparative example 6, by forming a carbon film on the surface of the magnetic layer in accordance with the use of the above lubricant, it is possible to perform severe conditions such as low temperature or high temperature and high humidity. Friction coefficient, still durability,
It has been found that the shuttle durability shows very good results without deterioration.

Further, with respect to the sample tapes 1 to 14 and the comparative examples 1 to 6, the powder drop amount and the shuttle output decrease amount under the condition of the temperature of 25 ° C. and the humidity of 60% were measured, respectively. The results shown in are obtained. The amount of powder falling was evaluated by observing the surface of the magnetic layer with an optical microscope, and the amount of reduction in shuttle output was determined by the amount of reduction in output after 100 shuttle runs.

[0063]

[Table 7]

From Table 7, it is clear that in each of the sample tapes 1 to 14, the powder drop was small and the decrease in the output was very slight.

Experiment 2 First, on a surface of a base film made of polyethylene terephthalate having a thickness of 10 μm, isopropyl alcohol was used as a solvent, and a binder component containing acrylate as a main component and SiO ₂ particles (average particle diameter 18 nm) were dispersed and mixed. The coating was applied so that the density of the SiO ₂ particles would be 10 million particles / mm ² to provide surface protrusions.

Subsequently, a crucible arranged in a vacuum chamber was filled with a Co ₈₀ Ni ₂₀ (numerical value is% by weight) alloy, and this was heated and melted by a predetermined heating means while oblique vapor deposition was carried out by a usual method. Then, the magnetic material evaporated from the crucible was applied to the surface of the base film which was moved and run to form a metal magnetic thin film. At this time, oxygen gas was introduced into the surface of the base film at a rate of 300 cc / min, and the incident angle of the magnetic material with respect to the surface of the base film was set to change in the range of 40 to 90 °. The running speed of the base film was adjusted so that the thickness of the obtained metal magnetic thin film was 200 nm.

Then, a back coat layer containing urethane and carbon as main components was formed on the surface of the base film opposite to the surface on which the metal magnetic thin film was formed. Then, using a continuous winding type sputtering device, direct current magnetron sputtering was performed in an Ar gas atmosphere to form a carbon film on the surface of the metal magnetic thin film. In this sputtering, the degree of vacuum was set to 2 Pa, and the feeding speed of the magnetic tape was adjusted so that the resulting carbon film had a thickness of 20 nm. Also, the target has a width of 20
It was a square type with a length of 0 mm and a length of 150 mm, and the distance between the substrate and the target was 50 mm.

Further, this magnetic tape was cut into a width of 8 mm, and then the compound A or the compound B shown in Table 8 below was added to the Freon 113 at a concentration of 0.06% by weight, respectively.
Immerse in the lubricant that is dissolved in
A lubricant layer was formed on the surface of the carbon film to obtain sample tapes 15 and 16.

[0069]

[Table 8]

With respect to the sample tapes 15 and 16 thus produced, the still durability, shuttle durability and uneven wear amount were examined. The results are shown in Table 8 below. In addition, the still durability is -3d when output is -3d after running for 24 hours at normal temperature and humidity using a Sony VCR (brand name EV-S1 modified machine).
The time required to decrease B was examined. Shuttle durability is Sony VCR (product name EV-S900)
Evaluation was made based on the amount of attenuation of the output after 100 passes with respect to the output after 1 pass when repeatedly running for 60 minutes at room temperature and normal humidity. This shuttle durability is expressed by the following equation (1)
Represented by

[0071]

[Equation 1]

The uneven wear amount was evaluated by observing the step formed by forming an interference fringe with an optical microscope.

[0073]

[Table 9]

As is clear from Table 9, the use of an amine salt compound of perfluoropolyether having a carboxyl group at both ends or at one of the ends as a lubricant results in an uneven wear amount in each case. A small amount and good durability were obtained.

Experiment 3 First, a metal magnetic thin film was formed by depositing Co ₈₀ Ni ₂₀ (numerical value is% by weight) on the surface of a polyethylene terephthalate film having a thickness of 10 μm by a vacuum deposition method. At this time, oxygen gas was introduced into the surface of the base film at a rate of 250 cc / min, and the incident angle of the magnetic material with respect to the surface of the base film was set to 45 °.

Subsequently, sputtering was performed in an Ar gas atmosphere to form a carbon film on the surface of the metal magnetic thin film so as to have a film thickness of 20 nm. At the time of this sputtering, the Ar gas pressure was 300 ccM, and the magnetic tape feed rate was 1 m / min. Then, the magnetic tape was dipped at a speed of 1 m / min in a lubricant in which the compound C or the compound D shown in Table 9 was dissolved in Freon 113 at a concentration of 0.06% by weight, respectively. Then, a lubricant layer was formed on the surface of the carbon film to obtain each of the sample tapes 17 and 18.

With respect to each of the sample tapes 17 and 18 produced in this way, the still durability, shuttle durability, surface roughness and powder drop amount were examined. The results are shown in Table 10. The still durability is the time required for the output to drop by -3 dB when still running using a Sony VCR (trade name EV-S900), and the shuttle durability is the same as that of the above VCR. Represents the amount of output attenuation after 100 passes when the shuttle traveled for 2 minutes each time. In addition, the surface roughness was measured by Taristep (needle pressure 2 mg / mm ² ), and the powder drop amount was used by sliding the sample tapes 17 and 18 and the magnetic head into contact with each other and then using an optical microscope (magnification: 100 times). ), The surface of the magnetic head was observed and evaluated.

For comparison, a magnetic tape (comparative example 7) using a commercially available perfluoropolyether (trade name Z-DOL) instead of the compound C (or compound D) was also examined in the same manner, The results are also shown in Table 10.

[0079]

[Table 10]

As shown in Table 10, by using an amine salt compound of perfluoropolyether having a carboxyl group at the terminal as a lubricant, excellent durability can be obtained and powder drop can be very small. understood.

Therefore, the influence on the respective properties when the molecular weight of the perfluoropolyether derivative used as the lubricant was changed was examined. Experiment 4 After the metal magnetic thin film and the carbon film were sequentially formed on the base film in the same manner as in Experiment 3, various perfluoropolyether derivatives having different molecular weights were formed on the surface of the carbon film under the same conditions as in Experiment 3. A lubricant layer was formed by using the sample tapes 19 to 22. The molecular weight of the perfluoropolyether derivative used in this experiment is shown in Table 11 below.

With respect to each of the sample tapes 19 to 22 thus produced, the shuttle durability, the surface roughness and the friction coefficient were measured in the same manner as in Experiment 3, and the results are shown in Table 11.

[0083]

[Table 11]

As shown in Table 11, the molecular weight of the perfluoropolyether derivative used as the lubricant is 140
When it is in the range of 0 to 4500, the friction coefficient can be sufficiently suppressed, and good durability can be obtained.
It was possible to prevent powder falling. On the other hand, when the molecular weight of the perfluoropolyether derivative is smaller than the above range (Comparative Example 9) or conversely too large (Comparative Example 10), the decrease in output after repeated running becomes large. Not only that, but the amount of falling powder increased.

Next, the relationship between the molecular weight of the polar group portion of the above-mentioned perfluoropolyether derivative and various characteristics was examined. Experiment 5 After the metal magnetic thin film and the carbon film were sequentially formed on the base film in the same manner as in Experiment 2, three types of perfluoro having different polar groups were formed on the surface of the carbon film under the same conditions as in Experiment 2. Each of the sample tapes 23 to 2 was formed by forming a lubricant layer using a polyether derivative.
5 was produced. The perfluoropolyether derivative has polar groups at both ends, and the structure and molecular weight of the polar group portion are as shown in Table 12 below.

With respect to each of the sample tapes 23 to 25 thus produced, the shuttle durability and the uneven wear amount were measured in the same manner as in Experiment 2, and the results are shown in Table 12. However, in this experiment, a modified VCR EV-S1 (trade name) manufactured by Sony Corporation was used when performing the shuttle durability test. For comparison, when a perfluoropolyether derivative having a polar group portion having a molecular weight of more than 120 was used as a lubricant (Comparative Example 10 and Comparative Example 11), the same measurement was carried out, and the results are shown. It is also shown in Table 12.

[0087]

[Table 12]

As shown in Table 12, the output deterioration after repeated running tended to increase as the molecular weight of the polar group portion increased. Similar results were obtained for the amount of uneven wear. From this, it was found that it is necessary to suppress the molecular weight of the polar group portion to 120 or less in order to secure good durability.

The magnetic recording medium of the present invention as described above is
When applied to the system like, excellent running property, wear resistance
It has excellent durability and durability, and you can expect good results.
It A. Recording / playback device configuration The color video signal is digitized and recorded on a magnetic tape.
For digital VTRs recorded on recording media, for broadcasting stations
D1 format component type digital VT
R and D2 format composite type digital V
TR has been put to practical use.

The former D1 format digital VTR
Is 1 for the luminance signal and the first and second color difference signals.
After A / D conversion at a sampling frequency of 3.5 MHz and 6.75 MHz, a predetermined signal processing is performed and recording is performed on a magnetic tape. Since the sampling frequency of these component components is 4: 2: 2. 4: 2:
It is also called two methods.

On the other hand, in the latter D2 format digital VTR, the composite color video signal is sampled with a signal having a frequency four times the frequency of the color subcarrier signal, A / D-converted, and subjected to predetermined signal processing. , I record it on a magnetic tape.

In any case, these digital VTs are
Since R is designed on the premise that both are used for broadcasting stations, image quality is given the highest priority, and a digital color video signal in which one sample is A / D converted into, for example, 8 bits is substantially compressed. It is designed to record without doing anything. Therefore, for example, a D1 format digital VTR can obtain a reproduction time of at most about 1.5 hours even if a large cassette tape is used, which is unsuitable for use as a general domestic VTR.

Therefore, in this embodiment, for example, 5 μm
A signal having a shortest wavelength of 0.5 μm with respect to the track width is recorded, a recording density of 8 × 10 ⁵ bits / mm ² or more is realized, and the recorded information is compressed in a form with little reproduction distortion. When used together, the present invention is applied to a digital VTR capable of recording / reproducing for a long time even if a magnetic tape having a tape width of 8 mm or less is used.

The structure of this digital VTR will be described below.

A. Signal Processing Unit First, the signal processing unit of the digital VTR used in this embodiment will be described. FIG. 1 shows the entire structure on the recording side. The input terminals indicated by 1Y, 1U, and 1V are provided with three primary color signals R from a color video camera,
A digital luminance signal Y formed from G and B and digital color difference signals U and V are supplied. In this case, the clock rate of each signal is the same as the frequency of each component signal of the D1 format. That is, the respective sampling frequencies are 13.5 MHz and 6.75 MHz, and the number of bits per sample is 8 bits. Therefore, the input terminals 1Y, 1U, 1
The data amount of the signal supplied to V is about 216 Mb
ps. The data amount of the blanking time is removed from this signal, and the data amount is compressed to about 167 Mbps by the effective information extraction circuit 2 that extracts only the information of the effective area.

Then, the luminance signal Y of the output of the effective information extraction circuit 2 is supplied to the frequency conversion circuit 3, and the sampling frequency is converted from 13.5 MHz to 3/4 thereof. As the frequency conversion circuit 3, for example, a thinning filter is used so that aliasing distortion does not occur. The output signal of the frequency conversion circuit 3 is supplied to the blocking circuit 5, and the order of the luminance data is converted into the order of blocks. The block forming circuit 5 is provided for the block encoding circuit 8 provided in the subsequent stage.

FIG. 3 shows the structure of a block which is a coding unit. This example is a three-dimensional block, and for example, by dividing a screen across two frames, a large number of unit blocks of (4 lines × 4 pixels × 2 frames) are formed as shown in FIG. In addition, in FIG. 3, a solid line indicates an odd field line, and a broken line indicates an even field line.

Of the outputs of the effective information extraction circuit 2,
The two color difference signals U and V are supplied to the sub-sampling and sub-line circuit 4, and after the sampling frequencies are respectively converted from 6.75 MHz to half thereof, the two digital color difference signals are selected line by line from each other, Combined with the data. Therefore, a line-sequential digital color difference signal is obtained from the sub-sampling and sub-line circuit 4. FIG. 4 shows the pixel configuration of the signal subsampled and sublined by the subsampling and subline circuit 4. In Figure 4, ○
Indicates a sub-sampling pixel of the first color difference signal U, and Δ
Indicates the sampling pixel of the second dye signal V, and x indicates the position of the pixel thinned by the sub-sample.

The line-sequential output signal from the sub-sampling and sub-line circuit 4 is supplied to the blocking circuit 6. In the blocking circuit 6, one blocking circuit 5
Similarly, the color difference data in the scanning order of the television signal is converted into the data in the block order. Like the one blocking circuit 5, the blocking circuit 6 converts the color difference data into a block structure of (4 lines × 4 pixels × 2 frames). The output signals of the blocking circuit 5 and the blocking circuit 6 are supplied to the synthesizing circuit 7.

In the synthesizing circuit 7, the luminance signal and chrominance signal converted in the order of blocks are converted into 1-channel data, and the output signal of the synthesizing circuit 7 is supplied to the block coding circuit 8. As the block encoding circuit 8, an encoding circuit (referred to as ADRC) adapted to the dynamic range of each block and a DCT (Dis) will be described later.
A create cosine transform circuit or the like can be applied. The output signal from the block encoding circuit 8 is further supplied to the framing circuit 9 and converted into frame structure data. In the framing circuit 9, the pixel system clock and the recording system clock are changed.

Next, the output signal of the framing circuit 9 is supplied to the error correction code parity generation circuit 10 to generate the error correction code parity. The output signal of the parity generation circuit 10 is supplied to the channel encoder 11, and channel coding is performed so as to reduce the low frequency part of the recording data. Channel encoder 11
Output signal of the pair of magnetic heads 13 via recording amplifiers 12A and 12B and a rotary transformer (not shown).
It is supplied to A and 13B and recorded on the magnetic tape. The audio signal and the video signal are separately compression-coded and supplied to the channel encoder 11.

By the above-mentioned signal processing, the input data amount 216 Mbps is reduced to about 167 Mbps by extracting only the effective scanning period, and further it is reduced to 84 Mbps by the frequency conversion, the sub-sample and the sub-line. This data is compressed and encoded by the block encoding circuit 8 to be compressed to about 25 Mbps,
By adding additional information such as parity and audio signal after that, the recording data amount becomes 31.56 Mbps.

Next, the structure on the reproducing side will be described with reference to FIG. At the time of reproduction, as shown in FIG. 2, reproduction data from the magnetic heads 13A and 13B is first supplied to the channel decoder 15 via the rotary transformer and the reproduction amplifiers 14A and 14B. Channel decoder 15
At, the channel coding is demodulated, and the output signal of the channel decoder 15 is supplied to the TBC circuit (time base correction circuit) 16. In this TBC circuit 16, the time-axis fluctuation component of the reproduction signal is removed. The reproduction data from the TBC circuit 16 is supplied to the ECC circuit 17,
Error correction using the error correction code and error correction are performed. The output signal of the ECC circuit 17 is supplied to the frame decomposition circuit 18.

The frame decomposition circuit 18 separates the respective components of the block coded data from each other, and
The clock of the recording system is changed to the clock of the pixel system. The respective data separated by the frame decomposing circuit 18 are supplied to the block decoding circuit 19, the restored data corresponding to the original data is decoded for each block, and the decoding data is supplied to the distribution circuit 20. The distribution circuit 20 separates the decoded data into a luminance signal and a color difference signal. The luminance signal and the color difference signal are supplied to the block decomposition circuits 21 and 22, respectively. The block decomposing circuits 21 and 22 convert the decoding data in the order of blocks into the order of raster scanning, contrary to the blocking circuits 5 and 6 on the transmission side.

The decoded luminance signal from the block decomposition circuit 21 is supplied to the interpolation filter 23. In the interpolation filter 23, the sampling rate of the luminance signal is 3 fs to 4 fs.
(4fs = 13.5 MHz). The digital luminance signal Y from the interpolation filter 23 is taken out to the output terminal 26Y.

On the other hand, the digital color difference signal from the block decomposition circuit 22 is supplied to the distribution circuit 24, and the line-sequential digital color difference signals U and V are separated into the digital color difference signals U and V, respectively. The digital color difference signals U and V from the distribution circuit 24 are supplied to the interpolation circuit 25 and are interpolated. The interpolation circuit 25 interpolates the data of the thinned lines and pixels by using the restored pixel data, and the sampling rate from the interpolation circuit 25 is 2f.
s digital color difference signals U and V are obtained and output terminal 2
6U and 26V are taken out respectively.

B. Block Coding As the block coding circuit 8 in FIG.
(Adaptive Dynamic Range Co
ding) encoder is used. The ADRC encoder detects the maximum value MAX and the minimum value MIN of a plurality of pixel data included in each block, and detects the maximum value MA.
The dynamic range DR of the block is detected from X and the minimum value MIN, the coding adapted to this dynamic range DR is performed, and the requantization is performed with the number of bits smaller than the number of bits of the original pixel data. As another example of the block encoding circuit 8, pixel data of each block is converted into DCT (Discrete Cosine Tran).
After sform), the coefficient data obtained by this DCT may be quantized, and the quantized data may be run-length Huffman encoded and compression-encoded.

Here, an example of an encoder which uses an ADRC encoder and in which image quality does not deteriorate even when multi-dubbing is performed will be described with reference to FIG. In FIG. 5, a digital video signal (or digital color difference signal) in which one sample is quantized into 8 bits is input to the input terminal 27 from the synthesizing circuit 7 in FIG. Input terminal 2
Blocked data from 7 is maximum and minimum value detection circuit 2
9 and the delay circuit 30. The maximum value / minimum value detection circuit 29 determines the minimum value MIN and the maximum value MAX for each block.
To detect. From the delay circuit 30, the input data is delayed for the time required to detect the maximum value and the minimum value.
The pixel data from the delay circuit 30 is supplied to the comparison circuit 31 and the comparison circuit 32.

The maximum value MAX from the maximum / minimum value detection circuit 29 is supplied to the subtraction circuit 33, and the minimum value MIN is supplied to the addition circuit 34. The subtractor circuit 33 and the adder circuit 34 are supplied from the bit shift circuit 35 with a value of one quantization step width (Δ = 1 / 16DR) when non-edge matching quantization is performed with a fixed length of 4 bits. The bit shift circuit 35 is configured to shift the dynamic range DR by 4 bits so as to perform division by (1/16). The subtraction circuit 33 obtains a threshold value of (MAX-Δ), and the addition circuit 34 obtains a threshold value of (MIN + Δ). The threshold values from the subtraction circuit 33 and the addition circuit 34 are supplied to the comparison circuits 31 and 32, respectively. The value Δ defining this threshold is not limited to the quantization step width and may be a fixed value corresponding to the noise level.

The output signal of the comparison circuit 31 is the AND gate 3
6 and the output signal of the comparison circuit 32 is supplied to the AND gate 37. The input data from the delay circuit 30 is supplied to the AND gate 36 and the AND gate 37. The output signal of the comparison circuit 31 becomes high level when the input data is larger than the threshold value, and therefore the output terminal of the AND gate 36 has the pixel data of the input data included in the maximum level range of (MAX to MAX-Δ). Is extracted. On the other hand, the output signal of the comparison circuit 32 becomes high level when the input data is smaller than the threshold value. Therefore, the output terminal of the AND gate 37 is (MIN to MIN).
The pixel data of the input data included in the minimum level range of + Δ) is extracted.

The output signal of the AND gate 36 is supplied to the averaging circuit 38, and the output signal of the AND gate 37 is supplied to the averaging circuit 39. These averaging circuits 38, 39
Calculates the average value for each block, and the reset signal of the block period from the terminal 40 is averaged by the averaging circuits 38, 39.
Is being supplied to. From the averaging circuit 38, (MAX ~
The average value MAX ′ of the pixel data belonging to the maximum level range of (MAX−Δ) is obtained, and the averaging circuit 39 outputs (MIN).
The average value MIN ′ of the pixel data belonging to the minimum level range of ˜MIN + Δ) is obtained. The subtraction circuit 41 subtracts the average value MIN ′ from the average value MAX ′.
From the dynamic range DR '.

Further, the average value MIN 'is supplied to the subtraction circuit 42, and the average value MIN' is subtracted from the input data passed through the delay circuit 43 in the subtraction circuit 42 to form the data PDI after removal of the minimum value. .. The data PDI and the modified dynamic range DR ′ are used by the quantization circuit 44.
Is supplied to. In this embodiment, the number of bits n assigned to quantization is 0 bit (code signal is not transferred),
It is a variable length ADRC that is any one of 1 bit, 2 bits, 3 bits, and 4 bits, and is subjected to edge matching quantization. The allocated bit number n is determined for each block in the bit number determination circuit 45, and the data of the bit number n is supplied to the quantization circuit 44.

The variable length ADRC has a dynamic range D
Efficient encoding can be performed by reducing the number of allocated bits n in a block having a small R ′ and increasing the number of allocated bits n in a block having a large dynamic range DR ′. That is, the threshold values for determining the number of bits n are set to T1 to T4 (T1 <T2 <T3 <
T4), the code signal is not transferred to the block of (DR ′ <T1), only the information of the dynamic range DR ′ is transferred, and the block of (T1 ≦ DR ′ <T2) is (n = 1). The block of (T2 ≦ DR ′ <T3) is (n = 2), the block of (T3 ≦ DR ′ <T4) is (n = 3), and the block of (DR ′ ≧ T4) is The block is (n = 4).

In such variable length ADRC, the threshold values T1.about.
By changing T4, the generated information amount can be controlled (so-called buffering). Therefore, the variable length ADRC can be applied to a transmission line such as the digital video tape recorder of the present invention which requires that the amount of generated information per field or frame be a predetermined value.

In the buffering circuit 46 for determining the threshold values T1 to T4 for making the generated information amount a predetermined value, a plurality of threshold value groups (T1, T2, T3, T4), for example, 3 are set.
Two sets are prepared, and these sets of thresholds are distinguished by the parameter code Pi (i = 0, 1, 2, ... 31). The generated information amount is set to monotonically decrease as the number i of the parameter code Pi increases. However, the quality of the restored image deteriorates as the amount of generated information decreases.

Threshold value T from buffering circuit 46
1 to T4 are supplied to the comparison circuit 47, and the dynamic range DR ′ through the delay circuit 48 is supplied to the comparison circuit 47. The delay circuit 48 delays DR ′ by the time required for the buffering circuit 46 to determine the threshold set. In the comparison circuit 47, the dynamic range DR ′ of the block is compared with each threshold value, the comparison output is supplied to the bit number determination circuit 45, and the allocated bit number n of the block is determined. In the quantizing circuit 44, the data PDI after the minimum value removal via the delay circuit 49 is converted into the code signal DT by the edge matching quantization using the dynamic range DR ′ and the allocated bit number n. The quantization circuit 44 is composed of, for example, a ROM.

The modified dynamic range DR 'and average value MIN' are output via the delay circuits 48 and 50, respectively, and the parameter code Pi indicating the set of the code signal DT and the threshold value is output. In this example, the signal that has been non-edge-match quantized is edge-match quantized newly based on the dynamic range information, so that image deterioration when dubbing is small.

C. Channel Encoder and Channel Decoder Next, the channel encoder 11 and the channel decoder 15 of FIG. 1 will be described. As shown in FIG. 6, the channel encoder 11 is an adaptive scramble circuit to which the output of the parity generation circuit 10 is supplied, and a plurality of M-sequence scramble circuits 51 are prepared. The M-sequence is selected so that an output having a small number of components and DC components can be obtained. The precoder 52 for the partial response class 4 detection method performs arithmetic processing of 1 / 1-D ² (D is a unit delay circuit). The output of the precoder 52 is passed through the recording amplifiers 12A and 13A to the magnetic head 1
Recording and reproduction are performed by 3A and 13B, and reproduction output is amplified by reproduction amplifiers 14A and 14B.

On the other hand, in the channel decoder 15, as shown in FIG. 7, the arithmetic processing circuit 53 on the reproducing side of the partial response class 4 performs 1 + D arithmetic on the outputs of the reproducing amplifiers 14A and 14B. Also,
In the so-called Viterbi decoding circuit 54, decoding of data resistant to noise is performed by an operation using the correlation and the likelihood of the data with respect to the output of the operation processing circuit 53. The output of the Viterbi decoding circuit 54 is supplied to the descrambling circuit 55, the data rearranged by the scrambling process on the recording side is returned to the original series, and the original data is restored. With the Viterbi decoding circuit 54 used in this embodiment, the reproduction C / N conversion is improved by 3 dB as compared with the case of performing the decoding for each bit.

D. The traveling magnetic heads 13A and 13B are attached to the drum 76 in an integrated structure as shown in FIG. A magnetic tape (not shown) is obliquely wound around the peripheral surface of the drum 76 at a winding angle slightly larger than 180 ° or slightly smaller than 180 °.
A and the magnetic head 13B are configured to scan the magnetic tape at the same time.

Further, the directions of the gaps of the magnetic head 13A and the magnetic head 13B are inclined in opposite directions (for example, the magnetic head 13A is inclined + 20 ° with respect to the track width direction, and the magnetic head 13B is inclined -20 °. Are set so that the amount of crosstalk between adjacent tracks is reduced by so-called azimuth loss during reproduction.

9 and 10 show the magnetic heads 13A and 1A.
3B shows a more specific structure in the case where 3B is an integral structure (so-called double azimuth head), and for example, the magnetic head 13 integral with the upper drum 76 rotated at a high speed.
A and 13B are attached, and the lower drum 77 is fixed. Here, the winding angle θ of the magnetic tape 78 is 16
The drum diameter is 6 ° and the drum diameter φ is 16.5 mm.

Therefore, on the magnetic tape 78, one field of data is divided into five tracks and recorded. With this segment system, the length of the track can be shortened, and the error due to the linearity of the track can be reduced.

As described above, by performing the simultaneous recording by the double azimuth head, the error amount due to the linearity can be reduced as compared with the case where the pair of magnetic heads are arranged at the facing angle of 180 °. In addition, since the head-to-head distance is small, the pairing adjustment can be performed more accurately. Therefore, with such a traveling system, recording / reproducing can be performed on a narrow track.

[0125]

As is apparent from the above description, the magnetic recording medium of the present invention has a carbon film formed on the magnetic layer, on which a perfluoropolyether derivative having extremely excellent lubricity is formed. Since it is retained as a lubricant, it can maintain lubricity under any use conditions.
In addition, the lubricity can be maintained for a long period of time. Therefore, according to the present invention, it is possible to provide a magnetic recording medium having excellent running properties, wear resistance, and durability under various usage conditions.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration on a recording side of a signal processing unit of a digital VTR that compresses and records a digital image signal in a form such that reproduction distortion is small.

FIG. 2 is a block diagram showing a configuration on a reproduction side of a signal processing unit.

FIG. 3 is a schematic diagram showing an example of a block for block coding.

FIG. 4 is a schematic diagram for explaining subsampling and sublines.

FIG. 5 is a block diagram showing an example of a block encoding circuit.

FIG. 6 is a block diagram showing an outline of an example of a channel encoder.

FIG. 7 is a block diagram showing an outline of an example of a channel decoder.

FIG. 8 is a plan view schematically showing an example of the arrangement of magnetic heads.

FIG. 9 is a plan view showing a configuration example of a rotating drum and a winding state of a magnetic tape.

FIG. 10 is a front view showing a configuration example of a rotating drum and a winding state of a magnetic tape.

[Explanation of symbols]

 1Y, 1U, 1V ... Component signal input terminals 5, 6 ... Blocking circuit 8 ... Block coding circuit 11 ... Channel encoders 13A, 13B ... Magnetic head 22 .... Channel decoder 26 ... Block decoding circuit 28, 29 ... Block decomposition circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Sato 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Magne Products Co., Ltd. (72) Yuichi Arisaka 6-chome, Kita-Shinagawa, Shinagawa-ku, Tokyo No. 5 and 6 in Sony Magne Products Co., Ltd.

Claims (4)

[Claims] 1. A magnetic recording medium comprising at least a magnetic layer on a non-magnetic support, wherein a carbon film is formed on the surface of said magnetic layer, and at both ends represented by the following chemical formula 1. A magnetic recording medium comprising an amine salt compound of perfluoropolyether having a carboxyl group as a lubricant. [Chemical 1] 2. A magnetic recording medium having at least a magnetic layer on a non-magnetic support, wherein a carbon film is formed on the surface of the magnetic layer, and at least one end represented by the following chemical formula 2 A magnetic recording medium characterized by containing an amine salt compound of perfluoropolyether having a carboxyl group as a lubricant. [Chemical 2] 3. The molecular weight of the amine salt compound of perfluoropolyether having a carboxyl group at the terminal is 1400.
4. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is 4500. 4. The polar group moiety of the amine salt compound of perfluoropolyether having a carboxyl group at the terminal has a molecular weight of 120 or less.
The magnetic recording medium described.