JP2001158895A - Lubricant, magnetic recording medium and magnetic head slider coated with the same, and magnetic recording device using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress abrasion of a protecting film caused by high speed contact sliding of a magnetic recording medium with a magnetic head slider. SOLUTION: Abrasions of a protection film of a magnetic recording medium and a magnetic head caused by high speed contact sliding are remarkably reduced by applying a lubricant film having a cross-linked structure in which adjacent perfluorpolyether molecules are intermolecularly lined by cross-linking molecules to bring the lubricant film to have a structure capable of absorbing energy by elastically deforming against the stress and diffusing deformation to surrounding to reduce locally given energy by dispersing and relaxing the contact stress generated by the contact sliding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant for preventing abrasion between a magnetic recording medium and a magnetic head slider, a magnetic recording medium and a magnetic head slider coated with the lubricant, and these magnetic recording media. And a magnetic recording apparatus using a magnetic head slider.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording apparatus, as a demand for an increase in recording capacity becomes remarkable, a higher recording density and
Technology development for speeding up is underway. Higher recording density and higher speed of the magnetic recording medium and the magnetic head slider are achieved by shortening the distance between the magnetic recording medium and the magnetic head and rotating the magnetic recording medium at high speed. In such a magnetic recording device, the problem of abrasion of the protective film of each of the magnetic recording medium and the magnetic head slider has become apparent because the probability of high-speed contact between the magnetic recording medium and the magnetic head slider has increased. These problems are the main cause of head crash.

Hitherto, in order to suppress such abrasion of the protective film, it has been considered effective to suppress the frictional force generated when the magnetic recording medium and the magnetic head slider are in sliding contact with each other. In order to suppress this frictional force, control the surface roughness and shape of the substrate, improve the protective film material,
Adjustment of the film thickness and the like have been studied and put to practical use.

For example, Japanese Patent Application Laid-Open No. 63-217519 discloses that the coefficient of friction between a magnetic recording medium and a magnetic head is determined by adding a metal such as Cr or Mn to graphite-like carbon of a protective film of a magnetic recording medium. There is disclosed an invention which is extremely small to improve running durability. Japanese Patent Application Laid-Open No. 62-42316 discloses that a lubricant is formed as a Langmuir-Blodgett film on a protective film to keep the coefficient of friction constant at 0.2 or less, thereby improving the lubricating film and the magnetic head. An invention for preventing wear is disclosed.

[0005]

However, in response to the further demand for higher recording density and higher speed in the future magnetic recording apparatus, a sufficient effect of suppressing the abrasion of the protective film is realized only by reducing the frictional force by the conventional technology. It is considered impossible.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lubricant capable of suppressing abrasion of respective protective films due to high-speed sliding of a magnetic recording medium and a magnetic head slider, as compared with the prior art. .

[0007]

Means for Solving the Problems The present inventor has conducted research on techniques for achieving such an object, and as a result,
The following findings were obtained. Rather than reducing friction,
It is more effective to attenuate the locally applied energy by dispersing and relaxing the contact stress generated at the time of contact between the magnetic recording medium and the magnetic head slider.
For this purpose, it is only necessary to realize a lubricating film having a structure that elastically deforms with respect to stress to absorb energy, or propagates the deformation to the surroundings to disperse energy. The present invention has been made based on this finding.

The lubricant according to the present invention includes, for example, a perfluoropolyether having any one of —CH ₂ OH, —COOH, and —NH ₂ groups at both ends independently, and a lubricant at both ends independently. -NX ₂ (X is _-CH 2 OH, -COO
H, -H, consisting of any one) fluorocarbon compound having 1 to 7 carbon atoms having the -NH ₂ group.

That is, a lubricating film having a crosslinked structure in which adjacent perfluoropolyether molecules (PFPE) are connected by a bridging molecule (Brdg) is provided on the surface of a magnetic recording medium or a magnetic head slider. Crosslinking is performed with the terminal groups provided at both ends of PFPE.
It is formed by connecting the terminal group of Brdg with a chemical bond. The type of chemical bond is a covalent bond, a hydrogen bond or an electrostatic bond.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of PFPE in the present invention is represented by, for example, the following general formula. General formula -CF _2- (O-CF ₂ -CF ₂ ) _p- (O-CF ₂ ) _q -O-CF ₂ -General formula -CF _2- (O-CF- (CF ₃ ) -CF ₂ ) _m -(O-CF ₂ ) _l -General formula-(O-CF ₂ -CF ₂ -CF ₂ ) _n -p, q, n, m, l represents an integer of 1 or more. However, the structure of the PFPE in the present invention is not limited to these. The molecular weight is not particularly limited, but the center molecular weight is preferably about 1,000 to 4,000.

The structure of Brdg connecting PFPEs is, for example, represented by the following general formula. General formula-(CF ₂ ) _n -General formula-(CF ₂ -CF (CF ₃ )) ₂ -n represents an integer of 1 to 7. However, Br in the present invention
The structure of dg is not limited to these.

In the magnetic recording medium according to the present invention, by applying the lubricant according to the present invention, the protective film is hardly worn even when high-speed contact sliding occurs frequently. Fig. 1 [1]
1 is a schematic sectional view showing an embodiment of a magnetic recording medium according to the present invention. Hereinafter, description will be made based on this drawing.

The magnetic recording medium 10 of the present embodiment comprises a substrate 1
1 (non-magnetic support), a base film 12, a magnetic film 13, a protective film 14, a lubricating film 15, and the like. Base film 12 on substrate 11
, A magnetic film 13 is formed, and a protective film 14 is formed thereon. The base film 12 may not be provided. Lubrication film 1
5 is applied on the protective film 14. The magnetic recording medium 10 comes into contact with or possibly has a magnetic head slider, and is, for example, a hard disk medium, a flexible disk medium, or a magnetic tape medium.

The substrate 11 is not limited except that it is non-magnetic. That is, in the case of a hard disk medium, aluminum, glass, plastic, carbon,
In the case of a flexible disk medium or a magnetic tape medium such as silicon, a synthetic resin such as polyacetate can be exemplified.

A base film 12 is provided between the substrate 11 and the magnetic film 13.
May be provided. There is no limitation on the material of the base film 12, and examples thereof include Cr and Ni-P.

The method and material for forming the magnetic film 13 are not limited. In other words, coating, plating,
Examples include vapor deposition, sputtering, and CVD. For the material, metals such as Fe, Co, Ni and their oxides, or Co-Ni, Co-Pt, Fe-Ni, Fe-Co-Ni, Co-Cr-Pt
Alloys such as -Ta can be exemplified.

The protective film 14 is not limited at all, and examples thereof include amorphous carbon, hydrogenated carbon, nitrogen-added carbon, fluorine-added carbon, various metal-added carbon, diamond-like carbon, and silicon dioxide film.

The method of applying the lubricant according to the present invention on the protective film 14 to form the lubricating film 15 and the thickness thereof are not particularly limited. In the case of a hard disk medium, a dipping method can be exemplified. In this case, the lubricating film 15
Has a thickness of about 1 to 100 [Å], preferably 1 to 10
[Å] degree.

In the magnetic head slider according to the present invention, by applying the lubricant according to the present invention, the protective film is hardly worn even when high-speed contact sliding occurs frequently. FIG.
[2] is a schematic sectional view showing an embodiment of a magnetic head slider according to the present invention. Hereinafter, description will be made based on this drawing.

The magnetic head slider 20 of this embodiment is
It comprises a base material 21, a protective film 22, a lubricating film 23, and the like. Substrate 2
The protective film 22 is formed on 1. The lubricating film 23 is applied on the protective film 22. The magnetic head slider 20 is in contact with or has a possibility of contacting the magnetic recording medium, and is specifically a magnetic head slider for a hard disk, a magnetic head slider for a flexible disk, or a magnetic head slider for a magnetic tape. A magnetic recording / reproducing element (not shown) is formed on the sliding surface 24 of the base 21.

The substrate 21 is not limited at all. That is, Al
Examples include ceramic materials such as ₂ O ₃ —TiC sintered bodies, metal oxides such as Al ₂ O ₃ , metal materials such as Ti, and non-metallic materials such as Si and C.

A protective film 22 is provided on the sliding surface 24. There is no limitation on the film forming method and material of the protective film 22. That is, examples of the film forming method include coating, vapor deposition, sputtering, and CVD. Examples of the material include plastic, amorphous carbon, hydrogen-added carbon, nitrogen-added carbon, fluorine-added carbon, various metal-added carbon, diamond-like carbon, and silicon dioxide film.

The method of applying the lubricant according to the present invention on the protective film 22 to form the lubricating film 23 and the thickness thereof are not particularly limited. As the method, a dipping method can be exemplified. In this case, the thickness of the lubricating film 23 is 1
About 100 [Å], preferably about 1 to 10 [Å].

FIG. 2 is a schematic diagram showing one embodiment of the magnetic recording apparatus according to the present invention. Hereinafter, description will be made based on this drawing.

The magnetic recording apparatus 30 of this embodiment includes the magnetic recording medium 10 of the above embodiment and a magnetic recording / reproducing element (not shown) for recording and reproducing information on and from the magnetic recording medium 10. Magnetic head slider 20
And an actuator (support spring 31, carriage 32, moving mechanism 33 and rotating mechanism 34) for positioning the magnetic head slider 20 on the magnetic recording medium 10, and a controller (not shown) for controlling the actuator and the magnetic recording / reproducing element. ).

Two magnetic recording media 10 are fixed at a certain interval. Each magnetic recording medium 10 is rotated by a rotation mechanism 34. In the vicinity of both sides of each magnetic recording medium 10, a total of four magnetic head sliders 20 are arranged so as to sandwich them. Each magnetic head slider 20 is supported by a carriage 32 via a support spring 31. The movement of the carriage 32 is controlled by a moving mechanism 33.

The magnetic recording device 30 is a magnetic disk device, the magnetic recording medium 10 is a magnetic disk medium, the magnetic recording / reproducing element is a composite type of a recording inductive element and a reproducing MR element, and a moving mechanism 33. Is a voice coil motor, the rotation mechanism 34 is a spindle motor, and the control unit is a microcomputer, its program, and its peripheral circuits.

It should be noted that a combination of the magnetic recording medium 10 and the conventional magnetic head slider or a combination of the conventional magnetic recording medium and the magnetic head slider 20 can provide a corresponding effect.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to demonstrate that a magnetic recording medium and a magnetic head slider coated with a lubricant according to the present invention are hard to wear their protective films even after prolonged high-speed contact sliding, a high-speed contact for 1000 hours was performed. The amount of wear of the protective film after sliding was measured and compared with the case of the conventional lubricant. Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

(Examples 1 to 7) PFPE having a terminal group (E _2-
The molecular structure of (PFPE) is OH-CH ₂ -CF _2- (O-CF ₂ -CF ₂ ) _p- (OC
F ₂ ) _q -O-CF ₂ -CH ₂ -OH (p, q is an integer of 1 or more), and the molecular structure of Brdg (E ′ ₂ -Brdg) having a terminal group is (HO) ₂ N- (CF ₂ ) _n -N
This is an example of a lubricant in which (OH) ₂ ; (n = 1 to 7).

1-1. Manufacture of magnetic recording media and head slider (1). Production of magnetic recording media for demonstration and magnetic head slider for demonstration

For the magnetic recording medium, a base film and a magnetic film were formed on a 2.5-inch glass substrate, and a carbon protective film was formed by a sputtering method. The thickness of the protective film was 10 [nm]. Regarding the magnetic head slider, 2.0 [nm] of Si is formed on the rail surface of the negative pressure pico slider made of Al ₂ O ₃ -TiC by CVD method, and a diamond-like carbon (DLC) protective film is formed on top of 8.0 [nm]. A film was formed. The total film thickness of Si and DLC film is 10 [n
m].

The communication between the magnetic recording medium and the magnetic head slider is performed.
A lubricant was applied by a usual dipping method. Dip
The solute of the solution is E_Two-PFPE and E '_Two-Brdg, against the former
The molar ratio of the latter (E '_Two-Brdg / E_Two-PFPE) was set to 1.0. Solute
The total concentration was 0.03 [%]. The solvent used was Perfluo
It is a low octane. The magnetic recording medium and the magnetic heads
Remove lid from dip solution and allow to dry at room temperature.
I let you. Such magnetic recording medium and magnetic head slider
7 kinds of samples for verifying the effect of were prepared. These sun
Pull is E '_TwoOnly the carbon number of the main chain of -Brdg differs. Sand
Chi, (HO)_TwoN- (CF_Two) _n-N (OH)_Two; (n = 1 to 7).

(2). Production of Reference Magnetic Recording Medium and Reference Magnetic Head Slider A reference magnetic recording medium and a reference magnetic head slider coated with a lubricant were produced in the same manner as in the above (1). However E _'2 -Brdg is not used, the dip solution is E ₂
-The concentration was set to 0.03 [%] only with PFPE.

1-2. Sliding test The magnetic recording medium and head slider manufactured by the above method 1-1 were slid in a state where they were in contact with each other, and the protective film thickness before and after sliding for 1000 hours was measured by ellipsometry. Then, the protective film wear amount {(film thickness before sliding) − (film thickness after 1000 hours of sliding)} was evaluated. In the sliding test, the magnetic recording medium to be evaluated is mounted on the spindle, the magnetic head slider is adjusted so as to press against the surface of the magnetic recording medium with a load of 2.5 [g], and the magnetic head slider is mounted in the outer or inner circumferential direction. It is fixed so that it does not move and the rotational speed of the magnetic recording medium is set to 10,000 [rp
m]. The linear velocity at this time was 2.6 [m / s].

1-3. Test Results Table 1 shows the results prepared by the method described in 1-1 above and tested by the method described in 1-2.

Table 1. The magnetic recording medium and n values medium protection sliding test results E _'2 -Bedg by the magnetic head slider film wear amount slider protective film wear amount of Example 1 1 0.6 were coated with a lubricant according to the present invention [nm] 0.8 [nm ] Example 2 2 0.5 [nm] 0.7 [nm] Example 3 3 0.5 [nm] 0.6 [nm] Example 4 4 ND 0.1 [nm] Example 5 5 0.7 [nm] 0.9 [nm] Example 6 6 0.8 [nm] 1.0 [nm] Example 7 7 0.8 [nm] 1.2 [nm] Reference − 7.5 [nm] 10 [nm] * ND = Measurement lower limit (0.05 [nm]) or less

From Table 1, it can be seen that the magnetic recording medium and the magnetic head slider coated with the lubricating film according to the present invention are more abrasion-resistant than the conventional ones (reference magnetic recording medium and magnetic head slider) with respect to the abrasion of the protective film due to sliding. The amount was found to be significantly reduced.

(Examples 8 to 14) The molecular structure of E ₂ -PFPE was
OH-CH ₂ -CF _2- (O-CF ₂ -CF ₂ ) _p- (O-CF ₂ ) _q -O-CF ₂ -CH _2-
OH (p, q is an integer of 1 or more), E 'molecular structure of ₂ -Brdg is (HOOC)
₂ is a _{N- (CF 2) n -N (} COOH) 2 (n = 1~7 integer) is an example of the lubricant.

2-1. Manufacture of magnetic recording media and head slider (1). Production of Magnetic Recording Medium for Demonstrating Effect and Magnetic Head Slider for Demonstrating Effect A magnetic recording medium and a magnetic head slider were produced in the same manner as the method described in 1-1 (1) above. Where E ₂ -PFPE
And E ′ ₂ -Brdg are those described in Examples 8 to 12, and E ′ ₂ −
Brdg / E ₂ -PFPE was 0.5. Also, after applying lubricant, 100
[° C], heated for 1 hour.

(2). Production of Reference Magnetic Recording Medium and Reference Magnetic Head Slider A magnetic recording medium was produced by a method similar to the method described in 1-1 (2) above. However, E ₂ -PFPE was used that of Example 8-12 according.

2-2. Sliding test A sliding test was performed in the same manner as described in 1-2.

2-3. Test Results Table 2 shows the results prepared by the method described in 2-1 and tested by the method described in 2-2.

Table 2. The magnetic recording medium and the sliding test result E _'2 n value of -Bedg medium protective film wear amount slider protective film wear amount Example 8 1 0.5 According to the magnetic head slider was coated with a lubricant according to the present invention [nm] 0.9 [ nm] Example 9 2 0.6 [nm] 0.7 [nm] Example 10 3 0.5 [nm] 1.0 [nm] Example 11 4 0.5 [nm] 0.2 [nm] Example 12 5 0.6 [nm] 1.2 [nm] Example 13 6 0.8 [nm] 1.3 [nm] Example 14 7 1.0 [nm] 1.4 [nm] Reference-9.5 [nm] 10 [nm]

(Examples 15 to 21) The molecular structure of E ₂ -PFPE was HOOC-CF _2- (O-CF- (CF ₃ ) -CF ₂ ) _m- (O-CF ₂ ) ₁ -COOH
(m = 1 or more integer), the molecular structure of E ′ ₂ -Brdg is (H ₂ N) ₂ N− (CF ₂
-CF (CF ₃₎₎ is an example for ₂ -N (NH _{2) 2} in which lubricant.

3-1. Manufacture of magnetic recording media and head slider (1). Production of Magnetic Recording Medium for Demonstrating Effect and Magnetic Head Slider for Demonstrating Effect A magnetic recording medium and a magnetic head slider were produced in the same manner as the method described in 1-1 (1) above. Where E ₂ -PFPE
And E _'2 -Brdg was used that of Example 15 to 21, wherein.
E ' ₂ -Brdg / E ₂ -PFPE is 0.01, 0.1, 1.0, 5.0, 10, 50, 10
0 was set. After the lubricant was applied, heating was performed at 120 ° C. for 2 hours.

(2). Production of Reference Magnetic Recording Medium and Reference Magnetic Head Slider A magnetic recording medium was produced by a method similar to the method described in 1-1 (2) above. However, E ₂ -PFPE was used that of Example 15 to 21, wherein.

3-2. Sliding test A sliding test was performed in the same manner as described in 1-2.

3-3. Test Results Table 3 shows the results of the test prepared by the method described in 3-1 and tested by the method described in 3-2.

Table 3. Sliding test results using a magnetic recording medium and a magnetic head slider coated with the lubricant according to the present invention E ′ ₂ -Brdg / E ₂ -PFPE Abrasion amount of medium protective film Abrasion amount of slider protective film Example 15 0.01 0.8 [nm] 1.9 [nm] Example 16 0.1 0.4 [nm] 1.7 [nm] Example 17 1.0 ND 0.2 [nm] Example 18 5.0 0.2 [nm] 0.2 [nm] Example 19 10 1.0 [nm] 1.5 [nm] Example 20 50 1.5 [nm] 2.3 [nm] Example 21 100 2.5 [nm] 3.4 [nm] Reference − 10 [nm] 10 [nm]

Table 3 shows that the magnetic recording medium and the magnetic head slider coated with the lubricating film according to the present invention are more abrasion-resistant than the conventional ones (reference magnetic recording medium and magnetic head slider). The amount was found to be significantly reduced.

[0052]

According to the lubricant, the magnetic recording medium, the magnetic head slider, and the magnetic disk drive of the present invention, the lubricant is elastically deformed with respect to stress to absorb energy or to transmit the deformation to the surroundings. By employing the lubricating film having the structure described above, the contact stress generated at the time of contact between the magnetic recording medium and the magnetic head slider can be dispersed and relaxed. Therefore, since the energy locally applied to the protective film below the lubricating film can be attenuated, abrasion of the protective film can be further suppressed as compared with the related art in which only the frictional force is reduced.

[Brief description of the drawings]

FIG. 1 [1] is a schematic sectional view showing an embodiment of a magnetic recording medium according to the present invention. FIG. 1B is a schematic cross-sectional view showing one embodiment of the magnetic head slider according to the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of a magnetic recording device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic recording medium 11 Substrate (nonmagnetic support) 12 Underlayer 13 Magnetic film 14 Protective film 15 Lubricating film 20 Magnetic head slider 21 Base material 22 Protective film 23 Lubricating film 30 Magnetic recording medium 31 Support spring (actuator) 32 Carriage ( Actuator) 33 Moving mechanism (actuator) 34 Rotation mechanism (actuator)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C10N 40:18 C10N 40:18

Claims (9)

[Claims] 1. A lubricant having a crosslinked structure in which adjacent perfluoropolyether molecules are connected by crosslinking molecules. 2. Both ends are independently -CH ₂ OH, -C
OOH, a perfluoropolyether having one of _a -NH ₂ group, _-NX independently on either side of the terminal 2 (X is _-CH 2 OH, -COOH, -H, any one of the -NH ₂ group And a fluorocarbon compound having 1 to 7 carbon atoms having 3. The lubricant according to claim 2, wherein a terminal group of said perfluoropolyether and a terminal group of said fluorocarbon compound are chemically bonded. 4. The ratio of the number of moles of the fluorocarbon compound to the number of moles of the perfluoropolyether is 0.0
The lubricant according to claim 2, wherein the lubricant is 1 to 100. 5. 5. A magnetic film is formed on a non-magnetic support, a protective film is formed on the magnetic film, and the lubricant according to claim 1, 2, 3 or 4 is applied on the surface of the protective film. Also, a magnetic recording medium. 6. A magnetic head slider, wherein the lubricant according to claim 1, 2, 3, or 4 is applied to a sliding surface on which a magnetic recording / reproducing element is provided. 7. A magnetic recording medium according to claim 5, a magnetic head slider having a magnetic recording / reproducing element for recording / reproducing information on / from the magnetic recording medium, and the magnetic head slider mounted on the magnetic recording medium. A magnetic recording device comprising: an actuator for positioning; and a control unit for controlling the actuator and the magnetic recording / reproducing element. 8. The magnetic head slider according to claim 6, further comprising a magnetic recording medium, and a magnetic recording / reproducing element for recording and reproducing information on and from the magnetic recording medium, and mounting the magnetic head slider on the magnetic recording medium. A magnetic recording device comprising: an actuator for positioning; and a control unit for controlling the actuator and the magnetic recording / reproducing element. 9. The magnetic head slider according to claim 6, further comprising a magnetic recording medium according to claim 5, and a magnetic recording / reproducing element for recording and reproducing information on and from the magnetic recording medium.
A magnetic recording apparatus comprising: an actuator for positioning the magnetic head slider on the magnetic recording medium; and a control unit for controlling the actuator and the magnetic recording / reproducing element.