JPH103648A - Magnetic recording media - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a lubricative layer which exhibits a good lubricative effect over a long period of time and has an excellent traveling property, wear resistance, durability, etc., and more particularly a still characteristic and shuttle characteristic. SOLUTION: At least a magnetic layer 2 and the lubricative layer 3 are formed on the nonmagnetic base 1 of this recording medium. In such a case, the lubricative layer 3 is formed of a perfluoropolyether based lubricant and fluorine carbide based lubricant. In addition, the lubricative layer 3 is regulated to a prescribed range in the characteristic value derived from a spectral charge obtd. by subjecting the lubricative layer 3 to an X-ray photoelectric spectral analysis.

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 having a lubricating layer on its surface, such as a magnetic tape or a magnetic disk. In particular, the present invention relates to a magnetic recording medium having a lubricating layer exhibiting a good lubricating effect over a long period of time, and having excellent running properties, wear resistance, durability and the like.

[0002]

2. Description of the Related Art As one of magnetic recording media, there is known a metal thin film type in which a magnetic layer is formed by depositing a ferromagnetic metal material on a nonmagnetic support by a vapor deposition method or the like. In this type of magnetic recording medium, the surface of the magnetic layer is very smooth, so that a substantial contact area with a sliding member such as a magnetic head or a guide roller is increased. However, there is a drawback that running and durability are apt to occur.

[0003] For example, a magnetic tape inserted into an 8 mm video deck is kept at a constant tape tension (about 20 g) and a constant tape running speed (0.5 cm / sec) by a pinch roller and a capstan, and is kept at 1 cm.
While being in contact with zero or more stainless fixed guide pins, it is wound around a drum. Therefore, when the coefficient of friction of the tape surface increases, the tape causes a stick-slip, so-called tape squealing occurs, and the reproduction screen becomes tight. In addition, since the relative speed between the tape and the head is very high, high-speed contact is made at the same place, especially in a pause state, so that there is a problem that the magnetic layer is worn and the reproduction output is reduced. This problem becomes very serious in the case of a vapor-deposited tape having a very thin magnetic layer.

In a hard disk drive, C
An SS (contact start / stop) operation, that is, an operation in which the magnetic head comes into contact with the disk before rotation and flies by an air flow generated when the magnetic head starts rotating at high speed is performed. Therefore, at the time of starting or stopping, the medium is run by rubbing the medium, and an increase in friction at that time is a serious problem. In order to maintain specific product level reliability, C
It is desired that the friction coefficient after performing the SS operation 20,000 times is 0.5 or less. In addition, the problem of head crash between the head and the magnetic recording medium is also one of the problems in the thin-film magnetic recording medium because it rotates at a high speed.

[0005] In order to solve these problems, attempts have been made to topcoat various lubricants on the magnetic layer of the magnetic recording medium. With respect to the lubricant used for such a magnetic recording medium, the following (a) to (c)
The following characteristics are required: (a) having excellent low-temperature characteristics capable of securing an intended lubricating effect when used in a cold region; (b) minimizing the problem of spacing with a magnetic head as much as possible. In order to avoid this, the film can be formed extremely thin; and (c) the lubricating effect is maintained for a long time.

[0006] By the way, the lubricants conventionally used for forming the lubricating layer of the magnetic recording medium are roughly classified into three types: silicone-based lubricants, hydrocarbon-based lubricants and fluorine-based lubricants. .

[0007] Silicone-based lubricants are widely used in coating type magnetic recording media because of their excellent thermal stability and relatively low vapor pressure. However, when applied to a thin-film magnetic recording medium having very good surface properties, it is difficult to form an oriented lubricating film on the surface and to obtain satisfactory lubricating characteristics. That is, this lubricating layer does not show a sufficient lubricating effect, and has a defect that the lubricating properties in a pin-on-disc wear acceleration test or a CSS test are not sufficient.

[0008] Hydrocarbon-based lubricants are still used as mainstream lubricants in coating type magnetic recording media. However, in terms of thermal or chemical stability, hydrocarbon-based lubricants are generally not sufficient compared to silicone-based lubricants and fluorine-based lubricants. In addition, a frictional polymer is easily generated from the hydrocarbon-based lubricant by friction. When such a frictional polymer is generated, the friction coefficient of the lubricating layer is increased, which may cause a fatal defect in the magnetic recording medium. Further, in the case of hydrocarbon-based lubricants, since the vapor pressure is relatively high, the lubricants gradually evaporate from the surface of the magnetic recording medium, and there is a disadvantage that a stable lubricating effect cannot be obtained for a long period of time.

Fluorine-based lubricants are currently the most frequently used lubricants in thin-film magnetic recording media, and fluorocarbon-based lubricants and perfluoropolyether-based lubricants are known. Among them, perfluoropolyether-based lubricants are used more frequently than other fluorine-based lubricants because lubricating performance and surface protection are good. The reason is that the ether bond (—CF ₂ —O—CF ₂ —) of the partial structure in the perfluoropolyether-based lubricant is a flexible bond, so that the molecular weight is temporarily the same as that of other lubricants. This is probably because the viscosity is low and the viscosity does not change in a wide temperature range. Furthermore, it is chemically inert, has a low vapor pressure, and has excellent thermal or chemical stability.
Low surface energy, excellent boundary lubrication properties,
Furthermore, it has excellent water repellency.

Recently, it has been proposed to improve the adsorbability of a perfluoropolyether-based lubricant having such advantages to the surface of a magnetic recording medium, further reduce the coefficient of friction, and improve the useful life of the magnetic recording medium. , A polar group (eg, a hydroxyl group, a piperonyl group, etc.) at one or both ends of the molecule
Perfluoropolyether-based lubricants into which is introduced (Fomblim Z-DOL, Fomblim-AM2001, etc.) have also been developed.

[0011]

However, as described above, various improvements have been made to the lubricant. However, the above-mentioned required characteristics (a) of the lubricant for forming the lubricant layer of the magnetic recording medium have been described. The requirements of (c) to (c) are becoming increasingly higher. Therefore, when a lubricant capable of satisfying the requirements of even more stringent requirements has been developed and a lubricant layer is provided on a magnetic recording medium using the lubricant, It is required that the magnetic recording medium can realize particularly excellent still characteristics and shuttle characteristics, such as excellent running properties, wear resistance, and durability.

The present invention is intended to solve the problems of the prior art, and in particular, has a lubricating layer exhibiting a good lubricating effect over a long period of time, and has excellent running properties, wear resistance, durability and the like. In particular, it is an object of the present invention to provide a magnetic recording medium having excellent still characteristics and shuttle characteristics.

[0013]

Means for Solving the Problems The present inventors formed a lubricating layer of a magnetic recording medium from a mixture of a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant, and furthermore, formed the lubricating layer with an X-ray photoelectron. Spectroscopy ｛ESCA (Electron Spectr
oscopy for Chemical Analysis) The results obtained by processing the result of｝ based on a specific formula are found to be able to achieve the above-mentioned object by being included in a certain range. Reached.

That is, the present invention provides a magnetic recording medium comprising at least a magnetic layer and a lubricating layer formed on a nonmagnetic support, wherein the lubricating layer comprises a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant. Containing and lubricating layer ESCA
Then, the following equation (A)

[0015]

Z = [(C1 + C2) / (C1ref + C2ref)] / [(C3 + C4) / (C3ref + C4ref)] (A) (where C1 is -O-CF_TwoIn the partial structure represented by -O-
E obtained from an underlined single-bonded carbon atom
SCA spectral integrated intensity; C2 is -C-CF_Two-O
An underlined single bond carbon in the substructure represented by-
ESCA integrated intensity of the atom; C3 is -C-
CF_TwoUnderline single bond in the partial structure represented by -C-
Is the integrated intensity of the ESCA spectrum of the carbon atom in question; C4
Is -C-CF_ThreeUnderlined single bond in the substructure represented by
The integrated intensity of the ESCA spectrum of the carbon atom
C1ref has a thickness of at least 10 nm.
-When ESCA is applied to fluoropolyether lubricant
In addition, -O-CF_TwoSingle underline in the substructure represented by -O-
ESCA spectra obtained from the bonded carbon atoms
Vector integrated intensity; C2ref is at least 10 nm
Perfluoropolyether lubricant with a thickness of
In case of ESCA, -C-CF_TwoPartial structure represented by -O-
Obtained from underlined single-bonded carbon atoms during construction
ESCA spectral integrated intensity; C3ref
Fluorocarbon lubricants with a thickness of at least 10 nm
Is ESCA, -C-CF_TwoPart represented by -C-
Derived from underlined single-bonded carbon atoms in the structure
And the C4re
f is a fluorocarbon film deposited to a thickness of at least 10 nm
When ESCA is applied to the system lubricant, -C-CF_ThreeRepresented by
Derived from an underlined single-bonded carbon atom in a substructure
It is an ESCA spectrum integrated intensity obtained by the above. )
Characterized in that the value of Z defined is from 0.3 to 8.0.
A magnetic recording medium.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magnetic recording medium according to the present invention will be described in detail.

As an example of the magnetic recording medium of the present invention, a magnetic layer 2 is provided on a non-magnetic support 1 as shown in FIG.
A coating type magnetic recording medium having a structure in which a lubricant and a lubricating layer 3 are laminated by coating, or a non-magnetic support 1 as shown in FIG.
A thin-film magnetic recording medium having a structure in which a very thin magnetic layer 2, a protective layer 4 made of carbon or the like, and a lubricating layer 3 are laminated thereon by vapor deposition or the like.

In the magnetic recording medium of the present invention having such a structure, the lubricating layer 3 is formed of a mixture of a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant, and is defined by the above-mentioned formula (A). The value of Z is in the range of 0.3 to 8.0. The magnetic recording medium of the present invention having such characteristics is at least -5C to 40C.
Since it has a lubricating layer exhibiting good lubricity even under a wide range of severe conditions (80% relative humidity), it exhibits good running properties, abrasion resistance, durability, etc., still characteristics, and shuttle characteristics over a long period of time.

Next, the meaning of Z defined by the formula (A) will be described in detail.

FIG. 2 shows a spectrum chart obtained by a typical ESCA measurement of a lubricating layer formed from a mixture of a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant. According to the ESCA method, the type and chemical bonding state of the element near the surface of the sample can be analyzed from the energy spectrum of photoelectrons struck out of the atoms in the sample compound by irradiation with soft X-rays. Since it has a low photoelectron transmission capability, it has the characteristic that information within the range of 10 nm from the surface of the polymer base material, particularly the information on the extremely surface layer, can be obtained relatively strongly. In addition, as an example of specific conditions of ESCA measurement, X-ray intensity: 14 kV-300 W, X-ray anode type: Monochromator Al, Measurement X-ray: AlKα ray,
Measurement time: 15 minutes can be mentioned, and a spectrum is taken in a range of a binding energy of 299 eV to 289 eV of organic carbon bonded between carbon and fluorine activated by C1s. A specific device used for such a measurement is PHI5 manufactured by ULVAC-PHI.
A 400MC type can be used.

By dividing the spectrum chart of FIG. 2 according to the curve fitting method, it has the above-mentioned meaning.
C1, C2, C1ref, C2ref, C3, C4, C3ref and C4ref are obtained. Here, C1 and C2 are strongly affected by the abundance of the perfluoropolyether lubricant, and C3 and C4 are strongly affected by the abundance of the fluorocarbon lubricant. Also, [(C1
+ C2) / (C1ref + C2ref)] is the value of the perfluoropolyether-based lubricant in the lubricant layer in which the perfluoropolyether-based lubricant and the fluorocarbon-based lubricant and other known lubricants are mixed. Shows the ratio of the perfluoropolyether-based lubricant to the lubricating layer in which 100% of the lubricant is present at a thickness of at least 10 nm. Also, [(C3 + C4) / (C3re
f + C4ref)] is the value of the fluorocarbon lubricant in the lubricant layer in which the perfluoropolyether lubricant and the fluorocarbon lubricant and other known lubricants are mixed. The percentage of the lubricating layer that is 100% and has a thickness of at least 10 nm is shown.

Therefore, the larger the value of Z, the higher the proportion of the perfluoropolyether-based lubricant, indicating that Z
It means that the smaller the value of is, the larger the proportion of the fluorocarbon lubricant is, but in the present invention, the value of Z is 0.3 to
It is in the range of 8.0. This is because if the value of Z is less than 0.3, the wear resistance of the magnetic recording medium cannot be sufficiently improved, and if it exceeds 8.0, the still of the magnetic recording medium cannot be sufficiently reduced.

The value of Z can be adjusted as appropriate depending on the types and amounts of the perfluoropolyether-based lubricant and the fluorocarbon-based lubricant.

Next, the perfluoropolyether lubricant and the fluorocarbon lubricant used in the present invention will be described.

As the perfluoropolyether-based lubricant, a compound represented by the following formula (1), (2) or (3) can be preferably used. The compound represented by 4) can be preferably used.

[0026]

Embedded image ^{Rfe1-X-R 2 -Y-} R 1 (1) R 1 -Y-R 2 -X-Rfe2-X-R 2 -Y-R 1 (2) R 1 -X-Rfe2-X -R ¹ (3) in ^{R 1 -Y-R 2 -Rf (} 4) ( formula (1) ~ (4), Rfe1 is a perfluoropolyether group of monovalent, Rfe2 divalent perfluoropolyether An ether group, Rf is a monovalent fluorocarbon group,
R ¹ is a monovalent hydrocarbon group, and R ² is a divalent hydrocarbon group. X and Y are linking groups. ).

Here, preferred examples of the monovalent perfluoropolyether group of Rfe1 include those represented by formulas (5), (6) and (7).

[0028]

Embedded image F (CF ₂ CF ₂ CF ₂ O) _n- (5) CF ₃ (OCF (CF ₃ ) CF ₂ ) _m- (OCF ₂ ) _l- (6) F (CF (CF ₃ ) CF ₂ O) _k- (7) (where n, m, l, and k are integers of 1 or more). Here, the numerical values of n, m, l, and k are integers of 1 or more, but it is preferable to select a number such that the molecular weight of the monovalent perfluoropolyether group is 600 to 5000.

Preferred examples of the divalent perfluoropolyether group of Rfe2 include those represented by the formula (8)

[0030]

## STR00006 ##-(OC ₂ F ₄ ) _p (OCF ₂ ) _q- (8) (where p and q are integers of 1 or more). Here, the ratio of p / q is generally 0.5 to 2, but is not limited thereto.

Preferred examples of the monovalent fluorocarbon group for Rf include a perfluoroalkyl group. Among them. A perfluoroalkyl group having 4 to 6 carbon atoms is preferred.

The connecting groups X and Y are preferably flexible bonds such as -O-, -COO- and -CONH-.

A preferred example of the monovalent hydrocarbon group of R ¹ is a higher-valent hydrocarbon group having 10 or more carbon atoms in order to improve solubility in a solvent used when forming the lubricating layer 3 from a lubricant. Alkyl groups can be mentioned. Preferred examples of the divalent hydrocarbon group for R ² include lower alkylene groups such as methylene and ethylene.

If the lubricating layer 3 made of such a lubricant is too thin, a long-term lubricating effect cannot be obtained, and if it is too thick, the electromagnetic conversion characteristics of the magnetic recording medium are deteriorated. ５０50 nm.

In addition to the perfluoropolyether-based lubricant and the fluorocarbon-based lubricant, the lubricating layer 3 may include other conventionally known lubricants such as long-chain carboxylic acids or esters thereof, and long-chain carboxylic acids. Alcohol and the like can be appropriately used in combination.

Further, in order to achieve a desired lubricating effect even under more severe use conditions, a mixture of a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant is used in an amount of 30:
An extreme pressure agent of about 70 to 70:30 can be used in combination. Here, the extreme pressure agent causes frictional heat generated when metal contact (for example, metal contact between the metal layer of the metal tape and the metal guide of the VTR) occurs partially in the boundary lubrication region. Reacts with the metal surface to form a reaction product film, thereby lowering friction and preventing wear. The extreme pressure agent based on phosphorus, the extreme pressure agent based on sulfur,
Halogen-based extreme pressure agents, organometallic extreme pressure agents, composite extreme pressure agents, and the like can be used.

The lubricating layer 3 may further contain known rust preventives such as phenols, naphthols, quinones, nitrogen-containing heterocyclic compounds, oxygen-containing heterocyclic compounds, and the like. Sulfur-containing heterocyclic compounds and the like can be used.

In the magnetic recording medium of the present invention, as the non-magnetic support 1, a non-magnetic support used in a conventional magnetic recording medium can be used. For example, a plastic sheet such as polyethylene terephthalate, a glass substrate, etc. For example, an aluminum plate on which an insulating oxide film is formed can be used. If necessary, a surface cured film such as an NP film may be formed.

The magnetic layer 2 may be a metal magnetic thin film formed on the non-magnetic support 1 as a continuous film by a PVD method such as plating, sputtering, or vacuum evaporation, or a magnetic coating material containing a magnetic powder and a resin binder. On the non-magnetic support 1 and drying.

Here, as the metal magnetic thin film, Fe, C
o, Ni and other metals, Co-Ni alloys, Co-Pt alloys, Co-Pt-Ni alloys, Fe-Co alloys, Fe-C
In-plane magnetization recording metal magnetic films and Co-Cr-based alloy thin films made of o-Ni-based alloys, Fe-Ni-B-based alloys, Fe-Co-B-based alloys, Fe-Co-Ni-B-based alloys, etc. be able to. In particular, in the case of an in-plane magnetic recording metal magnetic thin film, Bi, Sb, Pb, Sn, Ga, In,
An underlayer of a low melting point non-magnetic material such as Ge, Si, Ti, etc. is formed, and a metal magnetic material is deposited or sputtered from a vertical direction to diffuse the low melting point non-magnetic material into the metal magnetic thin film. May be eliminated to ensure in-plane isotropy and improve coercivity.

As the magnetic powder used for forming the coating type magnetic film, the magnetic powder conventionally used for forming the magnetic layer of the coating type magnetic recording medium can be used. For example, ferromagnetic iron oxide particles, ferromagnetic CrO
₂ , fine particles of ferromagnetic cobalt ferrite (CoO—Fe ₂ O ₃ ), cobalt adsorbed oxide, ferromagnetic Fe—Co—Ni alloy, hexagonal barium ferrite, iron nitride and the like.

The ferromagnetic iron oxide fine particles are represented by the general formula F
When expressed as eOx, the value of x is 1.33 <x <1.5
1, maghematite (γ-Fe ₃
O ₄ , x = 4/3) and solid solutions thereof. Further, cobalt may be added to these ferromagnetic iron oxide resistant materials for the purpose of increasing coercive force.

The above-mentioned ferromagnetic CrO ₂ includes C
In addition to rO ₂ , Ru, Sn,
A material obtained by adding at least one of Te, Sb, Fe, Ti, V, and Mn to CrO ₂ can be used.

As the ferromagnetic alloy powder, Fe alloy powder,
Ni alloy powder, Fe-Co alloy powder, Fe-Ni alloy powder, Fe-Co-Ni alloy powder, Co-Ni alloy powder, F
e-Co-B alloy powder, Fe-Co-Cr-B alloy powder, M
n-Bi alloy powder, Mn-Bi alloy powder, Mn-Al alloy powder, Fe-Co-V alloy powder, or alloy powder of these with other metals can also be used.

As the resin binder and the solvent to be mixed with the magnetic powder, those conventionally used in magnetic paints can be used.

It should be noted that a back coat layer may be provided on the non-magnetic layer surface of the magnetic recording medium as required for the magnetic recording medium of the present invention. Further, in order to increase the adhesion strength between the magnetic layer and the non-magnetic support, an undercoat layer may be provided between the magnetic layer and the non-magnetic support.

The magnetic recording medium of the present invention can be manufactured by a known method. For example, in the case of the magnetic recording medium shown in FIG. 1A, a magnetic coating composed of a magnetic powder, a resin binder and a solvent is applied on the non-magnetic support 1 according to a known coating method and dried to form a magnetic layer. Form 2 A mixture comprising a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant is dissolved in a solvent, and the resulting solution is applied on a magnetic layer and dried to form a lubricant layer 3. Can be. In the case of the magnetic recording medium shown in FIG. 1B, a magnetic metal or an alloy is formed on the non-magnetic support 1 by a vapor deposition method or the like, and a carbon layer is further vapor-deposited as the protective layer 4. A mixture comprising a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant is dissolved in a solvent, and the resulting solution is applied on the magnetic layer 2 and dried to form the lubricant layer 3. Can be.

[0048]

The present invention will be described below in more detail with reference to examples.

Examples 1 to 7 and Comparative Examples 1 to 4 Cobalt was deposited to a thickness of 200 nm on a polyethylene terephthalate film having a thickness of 14 μm by oblique deposition to form a ferromagnetic metal thin film.

Next, the perfluoropolyether-based lubricant shown in Table 1 and the fluorocarbon-based lubricant shown in Table 2 were used in Table 3 or Table 4.
A toluene solution of a lubricant mixture mixed at the weight ratio shown in (1) above was applied onto the ferromagnetic metal thin film at a coating amount of 5 mg (solid content) / m
^A magnetic recording medium was prepared by coating so as to be ² . This medium was cut into a width of 8 mm to produce a sample tape.

[0051]

[Table 1] (Perfluoropolyether-based lubricant) lubricants No Rfe1 or Rfe2 R ² XYR ^{1 1} (formula _{(2)) -CF 2 (OC} 2 F 4) p (OCF 2) q OCF 2 - -C 2 H 4 - -O- -O- -C ₁₈ H ₃₇ 2 (Formula (3)) -CF ₂ (OC ₂ F ₄ ) _p (OCF ₂ ) _q OCF ₂ ---O---C ₁₂ H ₂₅ 3 (Formula ( 1)) CF ₃ (OCF (CF ₃ ) CF ₂ ) _p (OCF ₂ ) _q OCF ₂ --C ₂ H ₄ --O- -CONH- -C ₁₀ H ₂₁

[0052]

[Table 2] (Fluorocarbon lubricant) lubricants No Rf R ² XR ¹ 7 (formula _{(4)) CF 3 CF 2} CF 2 CF 2 CF 2 CF 2 - -CH 2 - -COO- -C 18 H 37 8 ( wherein _{(4)) CF 3 CF 2} CF 2 CF 2 CF 2 CF 2 - -C 2 H 4 - -O- -C 12 H 25 9 ( formula _{(4)) CF 3 CF 2} CF 2 CF 2 CF 2 - - C ₂ H ₄ --CONH- -C ₁₀ H ₂₁

[0053]

[Table 3]

[0054]

[Table 4]

For each of the obtained sample tapes,
The CA value was measured, and the Z value was calculated. The results are shown in Tables 3 and 4.

Under the conditions of a temperature of 25 ° C. and a humidity of 60%, a temperature of -5 ° C., and a temperature of 40 ° C. and a humidity of 80%, the friction coefficient before and after aging, still The durability and shuttle durability were measured. The results are shown in Tables 3 and 4.

Aging conditions The samples were left in a 60 ° C. atmosphere for one week without humidification.

Friction coefficient test Friction coefficient tester used: manufactured by Ryowa Denshi Co., Ltd. Temperature (relative humidity): 25 ° C. (60%); −5 ° C.
(−); 40 ° C. (80%) Shuttle speed: 5 mm / sec Moving distance: 50 mm Weight: 18 g Material of guide pin: SUS303 Surface roughness: 0.2 S The coefficient of friction is practically less than 0.3. It is desired.

Still durability test The decay time until the output decreased by 3 dB in the pause state was measured. Practically, it is desired that the decay time is 120 minutes or more.

For each shuttle durability test , the shuttle traveled for 2 minutes, and the output was 3
The number of shuttles until the decrease in dB was measured. In practice,
It is desired that the number of shuttles be 150 or more.

As can be seen from Tables 3 and 4, the magnetic recording medium of the present invention is excellent in friction coefficient, still durability and shuttle durability even under strictly conceivable use conditions from low temperature to room temperature to high temperature and high humidity. Showed the results.

On the other hand, in the case of the magnetic recording tape having no lubricating layer (Comparative Example 1), the friction coefficient, the still durability and the shuttle durability showed extremely insufficient results. In the case of a tape having a lubricating layer having a Z value of less than 0.3 (Comparative Example 2), the results other than the still durability and the shuttle durability before aging at 25 ° C. (60% humidity) were unsatisfactory. It was something. In the case of a tape having a lubricating layer having a Z value exceeding 8.0 (Comparative Examples 3 and 4), still durability before and after aging at 25 ° C. (60% humidity), shuttle durability before aging, and the like. -5
The results other than the friction coefficient after aging at 0 ° C were unsatisfactory.

[0063]

The magnetic recording medium of the present invention has a lubricating layer which exhibits a good lubricating effect over a long period of time under a wide range of temperature and humidity conditions. It has excellent characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic recording medium of the present invention (FIG.
(B)).

FIG. 2 shows a typical E of a lubricating layer formed from a mixture of a perfluoropolyether lubricant and a fluorocarbon lubricant.
It is a spectrum chart figure obtained by SCA measurement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nonmagnetic support 2 Magnetic layer 3 Lubrication layer 4 Protective layer

Claims (11)

[Claims] 1. A magnetic recording medium having at least a magnetic layer and a lubricating layer formed on a nonmagnetic support, wherein the lubricating layer contains a perfluoropolyether-based lubricant and a fluorocarbon-based lubricant, and When the lubricating layer is analyzed by X-ray photoelectron spectroscopy, the following equation (A) is obtained: Z = [(C1 + C2) / (C1ref + C2ref)] / [(C3 + C4) / (C3ref + C4ref) ] in (a) (wherein, C1 is, -O- C F ₂ -O- by X-ray photoelectron spectroscopy spectrum integral intensity obtained derived from a single bond to which carbon atoms underlined portion structure represented it is; C2 is, -C- C F ₂ -O-
Is the spectral integrated intensity of the carbon atoms in by single bonds underlined portion structure represented are; C3 is, -C- C F ₂ -C-
In some spectrum integral intensity of a single bond to which carbon atoms underlined portion structure represented; C4 is, -C- C F ₃ carbon atoms which are single bonds underlined portion structure represented C1ref is at least 10
nm of a perfluoropolyether lubricant was deposited to a thickness when X-ray photoelectron spectroscopy, -O- C F ₂ -O- by a single bond to which carbon atoms underlined portion structure represented is X-ray photoelectron spectroscopy spectrum integral intensity obtained derived from; C2ref, when at least 10nm of a perfluoropolyether lubricant was deposited to a thickness and X-ray photoelectron spectroscopy, -C- C F ₂ Is the integrated intensity of the X-ray photoelectron spectroscopy spectrum derived from the underlined single bonded carbon atom in the substructure represented by -O-; C3ref is
At least 10nm of a fluorocarbon-based lubricant was deposited to a thickness when X-ray photoelectron spectroscopy, -C- C F ₂ -C- singlet bonded to that carbon atom underlined portion structure represented by is X-ray photoelectron spectroscopy spectrum integrated intensity obtained by origin; and C4ref at least 10nm of a fluorocarbon-based lubricant was deposited to a thickness when X-ray photoelectron spectroscopy, tables in -C- C F ₃ X-ray photoelectron spectroscopy spectrum integrated intensity obtained from the underlined single-bonded carbon atom in the partial structure to be obtained. A) the value of Z defined in (3) is from 0.3 to 8.0. 2. A compound represented by the following formula (1), (2) or (3), wherein the perfluoropolyether-based lubricant is a compound represented by the following formula (4): the magnetic recording medium of claim 1, wherein it is: ## STR1 ## ^{Rfe1-X-R 2 -Y-} R 1 (1) R 1 -Y-R 2 -X-Rfe2-X-R 2 -Y-R 1 ^{(2) R 1 -X-Rfe2} -X-R 1 (3) in ^{R 1 -Y-R 2 -Rf (} 4) ( formula (1) ~ (4), Rfe1 monovalent perfluoropolyether group Rfe2 is a divalent perfluoropolyether group, Rf is a monovalent fluorocarbon group,
R ¹ is a monovalent hydrocarbon group, and R ² is a divalent hydrocarbon group. X and Y are linking groups. ). 3. The method according to claim 1, wherein the monovalent perfluoropolyether group is
Formula (5), (6) or (7) F (CF ₂ CF ₂ CF ₂ O) _n- (5) CF ₃ (OCF (CF ₃ ) CF ₂ ) _m- (OCF ₂ ) _l- (6) F (CF (CF 3) CF 2 O) k - (7) (. wherein, n, m, l, and k is 1 or more is an integer) and a magnetic recording according to claim 2, wherein Medium. 4. The magnetic recording medium according to claim 3, wherein the monovalent perfluoropolyether group has a molecular weight of 600 to 5,000. 5. The divalent perfluoropolyether group is
3. The magnet according to claim 2, wherein the formula (8) is-(OC ₂ F ₄ ) _p (OCF ₂ ) _q- (8), wherein p and q are integers of 1 or more. recoding media. 6. The magnetic recording medium according to claim 2, wherein the monovalent fluorocarbon group is a perfluoroalkyl group. 7. The perfluoroalkyl group having 4 to 4 carbon atoms.
7. The magnetic recording medium according to claim 6, wherein 8. X and Y each independently represent -O-, -C
3. The magnetic recording medium according to claim 2, which is OO- or -CONH-. 9. The magnetic recording medium according to claim 2, wherein R ¹ is a higher alkyl group. 10. The magnetic recording medium according to claim 2, wherein R ² is a lower alkylene group. 11. The magnetic recording medium according to claim 1, wherein the lubricating layer has a thickness of 0.5 to 10 nm.