JP2008140445A - Magnetic recording medium, magnetic head, and magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce wear of fullerene molecules used as the lubricant of a magnetic disk device, as regards a magnetic recording medium, a head slider, and a magnetic recording device. <P>SOLUTION: A lubricant layer 2 comprising nano-sized particles 3 composed of a material having solid lubricant properties and having 0.53 to 1.05 nm average particle diameter and a holding agent 4 containing the nano-sized particles 3 is provided to at least a part of an uppermost surface 1 of the magnetic recording medium. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium, a magnetic head, and a magnetic recording apparatus, and more particularly to a configuration for reducing wear in a magnetic recording medium or magnetic head using fullerene molecules as a protective layer or a lubricant layer. The present invention relates to a magnetic recording medium, a magnetic head, and a magnetic recording apparatus.

  In recent years, the demand for higher recording density for magnetic storage devices typified by magnetic disks and magnetic tape drives has unnecessarily increased, but in order to achieve higher recording densities for magnetic storage devices, It is necessary to reduce the magnetic gap between the head and the magnetic recording medium.

For this reason, for example, in a magnetic disk device, conventionally, the “flying amount” of a head slider that is a carrier of a magnetic head has been gradually decreased.
That is, the head slider uses the air flow generated by the rotation of the magnetic recording medium, and floats (approaches) just above the surface of the magnetic medium as if it were a kite. In recent products, this height is much less than 1 μm, and for example, has been designed as a value around 10 nm (= 0.01 μm).

  As described above, when the flying height is reduced, the possibility that the magnetic head and the magnetic recording medium come into contact with and slide with each other increases. Therefore, it is necessary to improve the friction resistance of the lubricant layer protecting the magnetic head or the magnetic recording medium. .

  Thus, for example, it has been proposed to use spherical carbon clusters collectively called fullerenes in conventional floating magnetic disk devices (see, for example, Patent Documents 1 to 4).

  Among these, Patent Document 1 proposes to use fullerene as a protective film for a magnetic medium or as a solid lubricating layer. In any case, fullerene molecules are a magnetic film or magnetic film serving as a base. It is thought that it adheres to the thermal oxidation layer.

In Patent Document 2, fullerene is deposited after the surface of the underlayer is cleaned.
In this case, since the bond strength with the surface can be estimated by the desorption temperature of fullerene, it is considered that the fullerene molecule is fixed to the base.

In Patent Document 3, fullerene molecules are attached to the disk by sublimation. In this case, it is considered that the fullerene molecules are also fixed to the base.
It has also been proposed to stack an amorphous carbon film on a fullerene molecule equivalent to 1/3 of a single layer deposited by spin coating on a magnetic layer, and to further apply a PFPE lubricant thereon. However, fullerene molecules in this case are incorporated in the carbon protective film.
In addition, this Patent Document 3 only mentions that “providing the lubricating film as an emulsion liquid or solution containing fullerene molecules” is “it is clear that those skilled in the art can conceive”. No disclosure has been made.

  Patent Document 4 discusses the relationship between the diameter of the fullerene molecule and the texture roughness of the disk, and the relationship between the diameter of the fullerene molecule and the flying height of the apparatus. However, it is assumed that the fullerene molecule is not located in the texture groove. Therefore, it is considered that the fullerene molecule is actually fixed to the base in this case as well.

  In addition, in order to further reduce the flying height from the present level, it has been screamed that it is necessary to give up the flying height of the head slider and quickly shift to a design that allows contact between the head slider and the magnetic medium.

For example, it has been proposed to use hollow nanocarbon, that is, fullerene molecules in a lubrication application in a contact-type magnetic disk device (see, for example, Patent Document 5).
Here, two methods are disclosed: using fullerene alone after being modified with a hydrophobic group to make it hydrophobic, and using a synthetic fluorine and fullerene together.

Furthermore, although it is disclosed that a “defect”, that is, a dangling bond is formed on the fullerene and fixed to the underlayer, “This fixing is not permanent, and when a force greater than the bonding force is applied. The bond is released, and the hollow nanocarbon moves over the protective layer. It is re-bonded and fixed at the stop position of the destination.
The dangling bond bond is generally a relatively strong bond, and it is estimated that a fairly strong external force is required to remove this strong bond. It is considered that the state is “close” to the ground.

  Incidentally, in a magnetic tape medium in which the magnetic head and the magnetic recording medium are always in contact and sliding, it has been proposed to use a fullerene deposited layer generated by a plasma polymerization method for protecting the magnetic tape medium (for example, (See Patent Document 6).

In this case, the fullerene deposited layer produced by the plasma polymerization method is excellent in mechanical strength, and is excellent in lubricity similarly to graphite due to the effect of π electrons, and fullerene is used as a solid lubricating layer. Therefore, it is considered that the fullerene molecule is fixed to the base also in this case.
Japanese Patent No. 2817502 JP 2004-519800 A Japanese Patent Application Laid-Open No. 07-235045 JP 2005-135565 A JP 2001-067644 A Japanese Patent Laid-Open No. 10-049855

  However, as described above, when the fullerene molecules are close to the “fixed” state with respect to the underlayer, the slip between the head slider and the magnetic recording medium occurs at a fixed point in the fullerene molecules. As a result, there is a problem that the wear of the fullerene molecule, that is, the deterioration of the disk device and the head contamination due to the destruction of the molecule are concerned.

  Accordingly, an object of the present invention is to reduce wear of fullerene molecules used as a lubricant in a magnetic disk device, particularly a contact-type magnetic disk device.

FIG. 1 is a block diagram showing the principle of the present invention, and means for solving the problems in the present invention will be described with reference to FIG.
In addition, the code | symbol 5 in a figure is a molecule | numerator of a retention agent.
See FIG. 1 In order to solve the above problems, the present invention provides a magnetic recording medium having an average particle diameter of 0.53 nm to 1.05 nm made of a material having solid lubricity on at least a part of the outermost surface 1. It has the lubricating layer 2 which consists of the holding agent 4 containing the nanosize particle 3 and the nanosize particle 3.

  In the contact-type magnetic disk device, when the lubricating layer 2 including the nano-sized particles 3 and the retaining agent 4 containing the nano-sized particles 3 is used, the nano-sized particles 3 are used when the nano-sized particles 3 are used for lubrication. Is used in a form that does not “adhere” to the outermost surface 1 serving as the underlayer, and in this case, the retaining agent 4 can have a function of preventing the nano-sized particles 3 from being detached.

Since the method using the thin film holding agent is a method using the physical adsorption phenomenon, the nano-sized particles 3 are compared with the desorption prevention method described in Patent Document 6 using dangling bonds. The rolling property is remarkably improved, and as a result, the bearing effect of the nano-sized particles 3 is exhibited.
The “magnetic recording medium” in the present invention is not limited to a magnetic disk but also includes a magnetic tape.

  The nano-sized particle 3 in this case is typically either a fullerene molecule or a fullerene derivative molecule, and C60 is typical as a fullerene, and a fullerene derivative molecule is a fullerene molecule. It means a molecule in which hydrogen or an alkyl group is bonded to the molecule, or a molecule containing a metal atom inside the fullerene molecule.

  In this case, it is confirmed that both the nano-sized particles 3 constituting the lubricating layer 2 and the organic substance molecules constituting the holding agent 4 are attached to at least a part of the surface of the magnetic recording medium. Important for rollability.

Further, when the surface free energy of the nano-sized particles 3 is γ _N , the surface free energy of the retaining agent 4 is γ _R , and the surface free energy of the underlayer of the lubricating layer 2 is γ _S ,
γ _N ≦ γ _R <γ _S
In the case of γ _N > γ _R , the aggregation of the nano-sized particles 3 occurs and the rolling property is lost. On the other hand, in the case of γ _R ≧ γ _S , the retaining agent 4 Aggregates and surface coverage decreases.

但し、γ＝γ₁ ^d ＋γ₁ ^h 及びγ＝γ₂ ^d ＋γ₂ ^h は夫々水の表面自由エネルギー及びジヨードメタンの表面自由エネルギーで、例えば、γ₁ ^d ＝２１．８ｍＮ／ｍ、γ₁ ^h ＝５１．０ｍＮ／ｍ、γ₂ ^d ＝４９．５ｍＮ／ｍ、及び、γ₂ ^h ＝１．３ｍＮ／ｍという値を用いて計算する。
なお、θ₁ は保持剤厚膜面、磁気記録媒体面、或いは、ヘッドスライダ面に対する水の接触角であり、また、θ₂ は保持剤厚膜面、磁気記録媒体面、或いは、ヘッドスライダ面に対するジヨードメタンの接触角であり、この場合の厚膜とは、測定に際して下地の固体の影響を受けない程に厚く塗布した状態を意味する。 Note that the surface free energy γ in the present application is obtained by the Fowke equation expressed by the following equations (1) and (2).
γ = γ ^d + γ ^h (1)

Where γ = γ ₁ ^d + γ ₁ ^h and γ = γ ₂ ^d + γ ₂ ^h are the surface free energy of water and the surface free energy of diiodomethane, for example, γ ₁ ^d = 21.8 mN / m, γ ₁ ^h = Calculations are made using values of 51.0 mN / m, γ ₂ ^d = 49.5 mN / m, and γ ₂ ^h = 1.3 mN / m.
Θ ₁ is the contact angle of water with respect to the retaining agent thick film surface, the magnetic recording medium surface, or the head slider surface, and θ ₂ is the retaining agent thick film surface, the magnetic recording medium surface, or the head slider surface. Is a contact angle of diiodomethane with respect to, and the thick film in this case means a state in which it is applied so thick that it is not affected by the solid of the base during measurement.

Therefore, the surface free energy γ _N of the nano-sized particle 3 is obtained from the above formula (2) by measuring the contact angle of water and diiodomethane with respect to the surface of the nano-sized particle 3, and the surface free energy γ of the retaining agent 4 _R is obtained from the above equation (2) by measuring the contact angle of water and diiodomethane to the surface of the retaining agent 4, and the surface free energy γ _S of the underlayer of the lubricating layer 2 is determined relative to the surface of the lubricating layer 2. It can be obtained from the above formula (2) by measuring the contact angle between water and diiodomethane.

Further, when the nano-sized particle 3 is a fullerene molecule, the surface free energy is estimated to be about 40 mN / m for γ _N.
40 mN / m ≦ γ _R <γ _S
It is desirable to have the relationship

Further, as the above-mentioned retaining agent 4, a hydrocarbon-based oil agent, a cyclic hydrocarbon-based oil agent, or a fluorocarbon-based oil agent is desirable, and some of them include an unsaturated hydrocarbon, an aromatic ring structure, a hydroxyl group, Or you may have an amine structure.
Furthermore, as the retaining agent 4 that satisfies the above-described conditions, there is an amine salt or a lithium salt.

  Further, the adhesion thickness of the retaining agent 4 is preferably not more than 3 times the single particle thickness of the nano-sized particles 3, and if it exceeds 3 times, the structure as a thin film of the lubricating layer becomes unstable. More preferably, it is desired not to exceed twice the single particle thickness of the nano-sized particles 3.

  Moreover, as a minimum of the adhesion thickness of the holding | maintenance agent 4, it is desirable that it is 1/2 or more of the single particle film thickness of the nanosize particle 3, and when it is less than 1/2 of the single particle film thickness of the nanosize particle 3 In this case, it becomes difficult for the retaining agent 4 to sufficiently wet the nano-sized particles 3.

  Further, according to the present invention, in a head slider provided with a magnetic head, nano-sized particles 3 and nano particles 3 having an average particle diameter of 0.53 nm to 1.05 nm made of a material having solid lubricity on at least a part of the surface of the head slider. It has a lubricating layer 2 made of a retaining agent 4 containing size particles 3.

  Also in the head slider, the nanosize particles 3 are used in such a form that the nanosize particles 3 are not “fixed” to the outermost surface 1 as an underlayer by using the lubrication layer 2 composed of the nanosize particles 3 and the retaining agent 4 containing the nanosize particles 3. In this case, the retaining agent 4 has a function of preventing the nano-sized particles 3 from being detached.

  In this case, the composition of the nano-sized particles 3 and the holding agent 4, the relationship between the surface free energy, the film thickness, and the like are the same as in the case of the magnetic recording medium.

Further, by mounting at least one of the above-described magnetic recording medium and the above-described head slider, it is possible to realize a highly reliable magnetic recording apparatus, particularly a contact-type magnetic recording apparatus, corresponding to an increase in recording density. it can.
The “magnetic recording device” in the present invention is not limited to a magnetic disk device, but also includes a magnetic tape device.

  According to the present invention, since a thin film holding agent is used, it becomes a method using a physical adsorption phenomenon, and the rolling property of fullerene molecules is remarkably improved as compared with a conventional solid lubricant using fullerene molecules. As a result, the bearing effect of fullerene molecules is effectively exhibited.

  On the other hand, the wear of fullerene molecules, that is, the deterioration of the magnetic recording device and the head contamination caused by the destruction of the molecule can be effectively suppressed, thereby improving the reliability of the magnetic recording device including the magnetic disk device. Can be improved.

  The present invention provides an outermost surface of a magnetic recording medium in which a magnetic recording layer is provided on a nonmagnetic substrate via an underlayer, an intermediate layer, etc., and a carbon film such as a DLC (Diamond Like Carbon) film is provided thereon as a protective film. The surface of the protective film is made of a material having solid lubricity and has an average particle size of 0.53 nm (0.75 times the monomolecular film thickness of C60) to 1.05 nm (1 of the monomolecular film thickness of C60). (.Times.5) nano-sized particles, typically provided with a lubricating layer composed of a retentive agent containing either fullerene molecules or fullerene derivative molecules.

C60 is typical as a fullerene in this case, but it is not necessary to be pure C60, and other fullerenes such as C70 may be contained in a number ratio of less than 10%.
In addition, examples of the molecule of the fullerene derivative include a molecule in which hydrogen or an alkyl group is bonded to the fullerene molecule, or a molecule containing a metal atom inside the fullerene molecule.

  Further, the fullerene may be a polymerized fullerene in which a plurality of fullerenes are polymerized in a uniaxial direction, and may be carbon nanotubes instead of fullerenes. Works.

  Note that the nano-sized particles constituting the lubricating layer and the organic substance molecules constituting the retaining agent are attached to at least a part of the surface of the magnetic recording medium because of the rolling property of the nano-sized particles. Become important.

In addition, when the surface free energy of the nano-sized particles is γ _N , the surface free energy of the retaining agent is γ _R , and the surface free energy of the base layer of the lubricating layer is γ _S ,
γ _N ≦ γ _R <γ _S
In particular, when the nano-sized particle 3 is a fullerene molecule, the surface free energy is estimated as γ _N of about 40 mN / m.
40 mN / m ≦ γ _R <γ _S
To satisfy the relationship.
In addition, each surface free energy is calculated | required from the above-mentioned Fowke equation.

Further, as the retaining agent, a hydrocarbon-based oil agent, a cyclic hydrocarbon-based oil agent, or a fluorocarbon-based oil agent is desirable.
In this case, as the hydrocarbon-based oil, typically stearic acid derivatives, lauryl alcohol derivatives, and as the cyclic-hydrocarbon-based oil, typically polycyclic condensed naphthene derivatives, MAC (multiplied acrylated cyclohexane) derivatives, fluorides Typical examples of the carbon oil include perfluoroalkane derivatives and perfluoropolyether derivatives. A chemical structure in which a plurality of hydroxyl groups and amino groups are contained in the derivative molecule is preferable.

Moreover, you may have unsaturated hydrocarbon, an aromatic ring structure, a hydroxyl group, or an amine structure in some hydrocarbon-type oil agents, cyclic hydrocarbon-type oil agents, or fluorocarbon-type oil agents.
In this case, those containing unsaturated hydrocarbons are typically oleic acid derivatives, oleylamine derivatives, sulfurized olefin derivatives, and those containing aromatic ring structures are typically benzothiophene derivatives, carbazole derivatives, hydroxyl groups. Examples of those containing diol are typically glycol derivatives, glycerol derivatives, and those containing amine structures typically include ethylenediamine derivatives and aniline derivatives.

  Furthermore, as the retention agent, an amine salt, typically a dilauryl alkylamine salt derivative, an alkylamine palmitate derivative or a lithium salt, typically a lithium stearate derivative, a lithium adipate derivative is used. It is good.

Further, the adhesion thickness t _R of the retaining agent is, when the single particle thickness of the nano-sized particles is t _c ,
t _c / 2 ≦ t _R ≦ 3t _c
More preferably, t _c / 2 ≦ t _R ≦ 2t _c
It is desirable that t _c ≈0.7 nm when the nano-sized particles are C60.

Further, as a head slider provided with a magnetic head, a holding agent containing nano-sized particles having an average particle diameter of 0.53 nm to 1.05 nm made of a material having solid lubricity on at least a part of the surface of the head slider. A lubricating layer is provided.
In this case, the composition of the nano-sized particles and the holding agent, the relationship between the surface free energy, the film thickness, and the like are the same as those of the above-described magnetic recording medium.

  Further, it is intended to store and / or retrieve and / or output data such as images, sounds, numerical values, and characters, and a magnetic recording medium for storing data and a signal to the magnetic recording medium A magnetic head for magnetically writing to and reading from the head, a head slider for positioning the magnetic head with respect to the magnetic recording medium, and an actuator for sending and positioning the head slider to a predetermined position on the magnetic recording medium; A magnetic storage device including a control circuit for driving an actuator and a signal processing circuit for writing and reading information signals using a magnetic head is used as a magnetic recording medium from a material having solid lubricity. A head slider equipped with a magnetic recording medium having a lubricating layer made of a holding agent containing nano-sized particles and adhered to a part of its surface It is obtained by mounting the head slider adhered lubricating layer comprising a retaining agent containing nano-sized particles composed of a material having a solid lubricating property on a part of the surface thereof.

Here, with reference to FIG.2 and FIG.3, the magnetic disk of Example 1 of this invention is demonstrated.
See Figure 2
First, using a DC magnetron sputtering apparatus on a glass substrate 11, a Ta underlayer 12 having a thickness of 5 to 10 nm, a CoZrNb backing layer 13 having a thickness of, for example, 200 nm, and a Ru intermediate having a thickness of, for example, 15 nm. The layer 14 and a CoCrPt magnetic recording layer 15 having a thickness of, for example, 15 nm are sequentially deposited.

Next, a protective film 16 made of DLC (diamond-like carbon) having a thickness of, for example, 4 nm is deposited by performing plasma CVD in an atmospheric gas mixed with N ₂ gas.
The surface free energy γ _S of the protective film 16 at this time is, for example, 62 mN / m, and the surface free energy can be arbitrarily controlled by controlling the N concentration and the plasma output in the atmosphere during plasma CVD.
Note that the surface energy increases as the N concentration increases, and the surface energy also increases as the plasma output increases.

Next, a mixture of the fullerene molecules 18 and the holding agent 19 was applied on the protective film 16, the lubricating layer 17 was applied, the adhesion thickness of the holding agent 19 was t _R , and the single particle thickness of the fullerene molecules 18 was t _c . If
t _c / 2 ≦ t _R ≦ 3t _c
More preferably,
t _c / 2 ≦ t _R ≦ 2t _c
The thickness is formed.

In this case, the lower limit of t _R (t _c / 2) is a condition for the retaining agent 19 to sufficiently wet the fullerene molecule 18, and the upper limit of t _R (3 t _c ) is at least one of the fullerene molecules 18. This is a condition for allowing the part to come out of the liquid surface of the holding agent 19 and contact the mating surface, typically the surface of the head slider.
When t _R exceeds 3t _c , the fullerene molecule 18 may have a four-layer structure, the film structure becomes unstable, and the distance between the magnetic recording layer and the magnetic head becomes too large.

In the case of Example 1, C60 is used as the fullerene molecule 18, but the single particle film thickness t _c of C60 is t _c ≈0.7 nm, so that the adhesion thickness t _R of the retaining agent 19 is 0.35 nm. By setting the thickness to about 2.1 nm, for example, about 0.6 nm, the basic configuration of the magnetic disk 10 according to the first embodiment of the present invention is completed.
Here, tetraol [Z-tetraol (trade name, manufactured by Fomblin)], which is a kind of fluorocarbon lubricant and has a surface free energy γ _R of 47.0 mN / m, is used as the retaining agent 19.
In addition, the coating thickness of each film | membrane is measured, for example with a FTIR apparatus.

In this case, the surface free energy γ _F of C60 is estimated to be the same as that of the C-plane of graphite having substantially the same molecular structure, and is set to 40 mN / m here.
Therefore, the relationship between the surface free energy of the fullerene molecule 18, the holding agent 19, and the protective film 16 is
γ _F (= 40 mN / m) <γ _R (= 42 mN / m) <γ _S (= 62 mN / m)
It becomes.
The surface free energy is evaluated by a contact angle when pure water is dropped on the surface of the protective film 16.

In such a relationship, since γ _R <γ _S , the holding agent 19 spreads thinly on the surface of the protective film 16, and C 60 does not aggregate because γ _F <γ _R. A thin lubricating layer 17 is formed in a state where fullerene molecules 18 are dispersed in the retaining agent 19.

As a result, since the fullerene molecules 18 are stably present between the sliding surfaces, the bearing effect of the fullerene molecules 18 can be sufficiently obtained, and low friction and low wear are realized.
Further, since γ _F <γ _R , C60 does not aggregate to form a cluster, and frictional vibration does not occur, which is suitable for the contact method.

In order to confirm the effect of Example 1, five comparative examples with different surface free energy relationships will be described.
(Comparative Example 1)
In Comparative Example 1, a DLC film with γ _S = 42 mN / m was used as the protective film by changing the film forming conditions, and the surface free energy γ _R was a kind of fluorocarbon lubricant as a retaining agent. AM3001 (trade name, manufactured by Augmont) of 27.4 mN / m is used.
In this case, the relationship between the surface free energy of the fullerene molecule, the holding agent and the protective film is
γ _R (= 27.4 mN / m) << γ _F (= 40 mN / m) <γ _S (= 42 mN / m)
It becomes.

Here, since γ _R << γ _F , the wettability of the fullerene molecules 18 to the holding agent 19 is low, and the fullerene molecules 18 are likely to aggregate together to form a cluster. As a result, the bearing of the fullerene molecules The effect cannot be obtained effectively, resulting in high friction and high wear with vibration.

This vibration is generated when the head slider rides irregularly on clusters of fullerene molecules 18 which are formed by aggregation of the fullerene molecules 18 and are unevenly distributed.
In addition, since aggregation of fullerene molecules 18 and formation of clusters hinder the reduction of the magnetic gap between the magnetic head and the magnetic recording medium, the combination is inappropriate for the contact method.

(Comparative Example 2)
In Comparative Example 2, a DLC film with γ _S = 42 mN / m was used as the protective film by changing the film formation conditions, and Z-dol (fomblin), which is a kind of fluorocarbon-based lubricant, was used as the holding agent. (Trade name made by company) and Z-tetraol (trade name made by Fomblin Co., Ltd.) and a mixed holding agent mixed at a volume ratio of 1: 1 is used.

In this case, the relationship between the surface free energy of the fullerene molecule, the holding agent and the protective film is
γ _R (= 38.5 mN / m) ≈γ _F (= 40 mN / m) <γ _S (= 42 mN / m)
It becomes.
In this case, γ _R ≈γ _F , but the tendency is the same as in Comparative Example 1 to some extent.

(Comparative Example 3)
In Comparative Example 3, a DLC film of γ _S = 42 mN / m was used as the protective film by changing the film formation conditions, and Z-tetraol (trade name, manufactured by Fomblin) was used as the retaining agent. Is used.
In this case, the relationship between the surface free energy of the fullerene molecule, the holding agent and the protective film is
γ _F (= 40 mN / m) <γ _S (= 42 mN / m) <γ _R (= 47.0 mN / m)
It becomes.

Here, since the relationship of γ _R > γ _S is satisfied, that is, the surface free energy γ _R of the holding agent 19 is larger than the surface free energy γ _S of the surface of the protective film 16, the holding agent 19 with respect to the protective film 16 Since the wettability deteriorates, the retaining agent 19 is likely to be locally aggregated, and the retaining agent 19 cannot spread thinly on the surface of the protective film 16.

As a result, the bearing effect of the fullerene molecule 18 cannot be obtained effectively, resulting in high friction and high wear with intense vibration.
This is because the retaining agent 19 covers the surface of the protective film 16 in a mottled manner, so that locally high-friction portions and low-friction portions occur, and as a result, the head slider generates intense frictional vibrations. It is because it will do.

  In addition, since this head vibration is derived from this intense vibration, the posture of the head slider also vibrates, and as a result, there is an action that hinders the reduction of the magnetic gap between the magnetic head and the magnetic recording medium. Becomes unsuitable for contact recording.

(Comparative Example 4)
In Comparative Example 4, a DLC film having the same γ _S = 62 mN / m as in Example 1 is used as the protective film, and AM3001 (trade name, manufactured by Augmont) is used as the retaining agent.
In this case, the relationship between the surface free energy of the fullerene molecule, the holding agent and the protective film is
γ _R (= 27.4 mN / m) << γ _F (= 40 mN / m) << γ _S (= 62 mN / m)
It becomes.

Here, since γ _R << γ _F is satisfied, aggregation of the fullerene molecules 18 occurs, and the bearing effect of the fullerene molecules 18 cannot be obtained.

(Comparative Example 5)
In Comparative Example 5, a DLC film having the same γ _S = 62 mN / m as that in Example 1 was used as the protective film, and Z-dol (trade name manufactured by Fomblin) and Z-tetraol (same as those in Example 2) were used as the retaining agent. Fomblin product name) and a mixed retention agent mixed at a volume ratio of 1: 1 is used.

In this case, the relationship between the surface free energy of the fullerene molecule, the holding agent and the protective film is
γ _R (= 38.5 mN / m) ≈γ _F (= 40 mN / m) <γ _S (= 62 mN / m)
It becomes.
In this case, γ _R ≈γ _F , and similar to Comparative Example 2, the tendency is similar to Comparative Example 1 to some extent.

See Figure 3
FIG. 3 summarizes the above comparison results. From the comparison results, the surface free energy between the fullerene molecule, the holding agent and the protective film is
γ _F <γ _R <γ _S
It can be seen that it is important to have the relationship
In addition, all the retaining agents used in Comparative Examples 1 to 5 including Example 1 are fluorocarbon lubricants, and these adjust the magnitude of the surface free energy by the difference in the terminal functional groups. Can do.

As described above, in Example 1 of the present invention, between the surface free energy of the fullerene molecule, the holding agent and the protective film,
γ _F <γ _R <γ _S
Since the lubricating layer is formed using a lubricant in which fullerene molecules satisfying the above relationship are dispersed in a holding agent, the bearing effect of fullerene molecules can be effectively exhibited, and in a contact type magnetic disk device Therefore, it is possible to prevent deterioration of the lubricating layer and prevent deterioration of the magnetic disk device, head contamination, and the like.

Next, a head slider according to a second embodiment of the present invention will be described with reference to FIG. 4. Here, the head slider will be described as having a low flying height or hardly flying.
See Figure 4
4 is a schematic plan view of an ABS (Air Bear Surface) surface of the head slider according to the second embodiment of the present invention. The head slider 20 has a size of 1 mm × 1.25 mm, for example, Al ₂ O _3. A positive pressure pad 23 is provided on the inflow side of the slider main body 21 made of -TiC (AlTiC) via the step portion 22 and a center pad 24 for generating positive pressure on the outflow side and side rails 25 on both sides thereof. , 26 are provided.
The positive pressure pad 23 and the center pad 24 have the same height.
A groove 28 is provided at the rear end of the center pad 24, and a magnetic head is provided in the groove 28.

Further, the step portion 22 lower by 0.195 μm, for example, than the positive pressure pad 23 is formed in a “U” shape by a deep groove portion 27 lower by 3.6 μm, for example, than the positive pressure pad 23 in the central portion. In addition, the negative pressure is made in the “U” shaped part.
Low padding is achieved by the above pad arrangement.

4 is a schematic cross-sectional view of the main part in the vicinity of the outflow side end along the alternate long and short dash line connecting AA 'in the above figure. The outflow side end of the slider body 21 has an Al ₂ O ₃ film 31, lower magnetic shield layer 32, lower gap layer 33, magnetoresistive effect element 34, upper gap layer 35, upper magnetic shield layer 36, Al ₂ O ₃ film 37, main magnetic pole 38, interlayer insulating film 39, write A thin film magnetic head including a coil 40, an auxiliary magnetic pole 41, and an Al ₂ O ₃ film 42 is provided.

A protective film 43 made of a DLC film is provided on the surfaces of the positive pressure pad 23 and the center pad 24 and on the end face of the thin film magnetic head.
At this time, the surface free energy γ _H of the protective film 43 is, for example, 62 mN / m.

The head slider 20 having such a configuration is immersed in a solvent solution in which the fullerene molecules 18 and the holding agent 19 are dispersed in exactly the same manner as in the above-described first embodiment, and then pulled up, and then the fullerene molecules 18 are formed on the surface of the head slider 20 by the Dip method. A lubricating layer 44 is formed.
In addition, Z-tetraol (trade name manufactured by Fomblin) is used as the retaining agent 19 in the same manner as in Example 1.
At this time, in the region where the protective film 43 made of the DLC film is not provided, the solvent solution does not adhere, and thus the lubricating layer 44 including the fullerene molecule 18 is not formed.

Further, in this case the density of the fullerene molecules 18 by the 1.3~2.1g / cm ³ specific gravity of the solution because it is about 1.5 g / cm ^3, the dispersibility in the solution of the fullerene molecule 18 And can achieve a uniform coating state.
In addition, since the density of the fluorinated solvent is generally larger than 1, if it is mixed with another organic solvent such as methanol or isopropyl alcohol as a dispersion solution, the density of the solvent can be adjusted as necessary. .

Also in this case, when the adhesion thickness of the retaining agent 19 is t _{R and} the single particle thickness of the fullerene molecule 18 is t _c ,
t _c / 2 ≦ t _R ≦ 3t _c
More preferably,
t _c / 2 ≦ t _R ≦ 2t _c
The thickness is formed.

In this case, the relationship between the surface free energy (γ _H ) of the fullerene molecule 18, the holding agent 19, and the protective film 43 is
γ _F (= 40 mN / m) <γ _R (= 42 mN / m) <γ _H (= 62 mN / m)
Therefore, exactly as in the first embodiment, the holding agent 19 spreads thinly on the surface of the protective film 43 which is the outermost surface of the head slider, and C60 aggregates because γ _F <γ _R. Therefore, the fullerene molecules 18 are dispersed in the holding agent 19 to form a thin film-like lubricating layer 44. As a result, the bearing effect of the fullerene molecules 18 is efficiently exhibited.

Next, a magnetic disk device according to a third embodiment of the present invention will be described with reference to FIG.
See Figure 5
FIG. 5 is a conceptual plan view of the magnetic disk device according to the third embodiment of the present invention. The magnetic disk 10 provided with the lubricating layer containing the fullerene molecules according to the first embodiment is attached to the rotation shaft of the spindle motor 51. , And is fixed by a disc clamp ring 52.

  Further, the magnetic head slider 20 provided with the lubricating layer containing the fullerene molecules of the above-described second embodiment is attached to the tip portion of the head arm 53 via the suspension 54 and performs a seek operation in the radial direction of the magnetic disk 10. Do.

As mentioned above, although each Example of this invention was described, this invention is not restricted to the structure, conditions, and numerical value which were shown in each Example, A various change is possible, for example in said Example 1 The lubricating layer is formed by a coating method, but it may be formed by the Dip method as in the second embodiment.
On the contrary, in the second embodiment, the lubricating layer is formed by the Dip method. However, the lubricating layer may be formed by the coating method as in the first embodiment.

  In Example 2 described above, when the lubricating layer is formed by the Dip method, the dispersibility is increased using an organic solvent such as methanol, but a homogenizer is used without using an organic solvent. It may be dispersed by an external force.

  In the third embodiment, the magnetic disk and the head slider, in which at least a part of the surface is coated with a lubricating layer containing fullerene molecules, are used as the magnetic disk and the head slider. Such a configuration is essential. Instead, it is sufficient that at least one of the magnetic disk and the head slider is covered with a lubricating layer containing fullerene molecules.

Here, referring to FIG. 1 again, the detailed features of the present invention will be described again.
Again see Figure 1
(Supplementary note 1) At least a part of the outermost surface 1 has nanosize particles 3 having an average particle size of 0.53 nm to 1.05 nm made of a material having solid lubricity, and a retaining agent 4 containing the nanosize particles 3. A magnetic recording medium having a lubricating layer 2 made of
(Supplementary note 2) The magnetic recording medium according to supplementary note 1, wherein the nano-sized particles 3 are either fullerene molecules or fullerene derivative molecules.
(Additional remark 3) Both the said nanosize particle | grains 3 which comprise the said lubricating layer 2, and the organic substance molecule | numerator which comprises the retainer 4 are adhering to at least one part of the surface of the said magnetic recording medium, It is characterized by the above-mentioned. The magnetic recording medium according to appendix 1 or 2.
(Supplementary Note 4) The surface free energy obtained from the Fowke equation of the nano-sized particles 3 is γ _N , the surface free energy obtained from the Fowke equation of the retaining agent 4 is γ _R , and the Fowke equation of the base layer of the lubricating layer 2 When the obtained surface free energy is γ _S , γ _N ≦ γ _R <γ _S
The magnetic recording medium according to any one of appendices 1 to 3, wherein the magnetic recording medium has the following relationship:
(Supplementary Note 5) When the surface free energy obtained from the Fowke equation of the retaining agent 4 is γ _R and the surface free energy obtained from the Fowke equation of the base layer of the lubricating layer 2 is γ _S , 40 mN / m ≦ γ _R <Γ _S
The magnetic recording medium according to any one of appendices 1 to 3, wherein the magnetic recording medium has the following relationship:
(Appendix 6) The magnetic recording medium according to any one of appendices 1 to 5, wherein the retaining agent 4 is a hydrocarbon-based oil.
(Supplementary note 7) The magnetic recording medium according to any one of supplementary notes 1 to 5, wherein the retaining agent 4 is a cyclic hydrocarbon oil.
(Supplementary note 8) The magnetic recording medium according to any one of supplementary notes 1 to 5, wherein the retaining agent 4 is a fluorocarbon oil.
(Supplementary note 9) The magnetic recording medium according to any one of supplementary notes 6 to 8, wherein the retaining agent 4 has an unsaturated hydrocarbon in a part thereof.
(Supplementary note 10) The magnetic recording medium according to any one of supplementary notes 6 to 9, wherein the retaining agent 4 has an aromatic ring structure in a part thereof.
(Supplementary note 11) The magnetic recording medium according to any one of supplementary notes 6 to 9, wherein the retaining agent 4 has a hydroxyl group in a part thereof.
(Supplementary note 12) The magnetic recording medium according to any one of supplementary notes 6 to 9, wherein the retaining agent 4 has an amine structure in a part thereof.
(Supplementary note 13) The magnetic recording medium according to any one of supplementary notes 6 to 9, wherein the retaining agent 4 is an amine salt.
(Supplementary note 14) The magnetic recording medium according to any one of supplementary notes 6 to 9, wherein the retaining agent 4 is a lithium salt.
(Supplementary note 15) The magnetic recording medium according to any one of supplementary notes 1 to 14, wherein the adhesion thickness of the retaining agent 4 does not exceed three times the single particle thickness of the nano-sized particles 3 .
(Supplementary note 16) The magnetic recording medium according to supplementary note 15, wherein the adhesion thickness of the retaining agent 4 does not exceed twice the single particle thickness of the nano-sized particles 3.
(Additional remark 17) Magnetic recording of any one of additional remark 1 thru | or additional remark 16 characterized by the adhesion thickness of the said retention agent 4 being 1/2 or more of the single particle film thickness of the said nanosized particle 3. Medium.
(Supplementary note 18) A head slider provided with a magnetic head, wherein at least a part of the surface of the head slider has nano-sized particles 3 having an average particle diameter of 0.53 nm to 1.05 nm made of a material having solid lubricity. A head slider having a lubricating layer 2 made of a retaining agent 4 containing the nano-sized particles 3.
(Supplementary note 19) The head slider according to supplementary note 18, wherein the nano-sized particles 3 are either fullerene molecules or fullerene derivative molecules.
(Supplementary note 20) The supplementary note, wherein both the nano-sized particles 3 constituting the lubricating layer 2 and the organic substance molecules constituting the retaining agent 4 are attached to at least a part of the surface of the head slider. The head slider according to 18 or 19.
(Supplementary Note 21) The surface free energy obtained from the Fowke equation of the nano-sized particles 3 is obtained from γ _N , the surface free energy obtained from the Fowke equation of the retaining agent 4 is obtained from γ _R , and obtained from the Fowke equation on the surface of the head slider. When the surface free energy is γ _H ,
γ _N ≦ γ _R <γ _H
21. The head slider according to any one of appendices 18 to 20, wherein the head slider has the following relationship.
(Supplementary Note 22) When the surface free energy obtained from the Fowke equation of the retaining agent 4 is γ _R and the surface free energy obtained from the Fowke equation of the surface of the head slider is γ _H ,
40 mN / m ≦ γ _R <γ _H
21. The head slider according to any one of appendices 18 to 20, wherein the head slider has the following relationship.
(Supplementary note 23) The head slider according to any one of supplementary notes 18 to 22, wherein the retaining agent 4 is a hydrocarbon-based oil.
(Supplementary note 24) The head slider according to any one of supplementary notes 18 to 22, wherein the retaining agent 4 is a cyclic hydrocarbon-based oil.
(Supplementary note 25) The head slider according to any one of supplementary notes 18 to 22, wherein the retaining agent 4 is a fluorocarbon oil.
(Supplementary note 26) The head slider according to any one of supplementary notes 23 to 25, wherein the retaining agent 4 has an unsaturated hydrocarbon in a part thereof.
(Supplementary note 27) The head slider according to any one of supplementary notes 23 to 26, wherein the retaining agent 4 has an aromatic ring structure in a part thereof.
(Supplementary note 28) The head slider according to any one of supplementary notes 23 to 26, wherein the retaining agent 4 has a hydroxyl group in a part thereof.
(Supplementary note 29) The head slider according to any one of supplementary notes 23 to 26, wherein the retaining agent 4 has an amine structure in a part thereof.
(Supplementary note 30) The head slider according to any one of supplementary notes 23 to 26, wherein the retaining agent 4 is an amine salt.
(Additional remark 31) The said slider 4 is a lithium salt, The head slider of any one of Additional remarks 23 thru | or 26 characterized by the above-mentioned.
(Supplementary note 32) The head slider according to any one of supplementary notes 18 to 31, wherein the adhesion thickness of the retaining agent 4 does not exceed three times the single particle thickness of the nano-sized particles 3.
(Additional remark 33) The head slider of Additional remark 32 characterized by the adhesion thickness of the said retaining agent 4 not exceeding twice the single particle film thickness of the said nanosized particle 3.
(Supplementary note 34) The head slider according to any one of supplementary notes 18 to 33, wherein an adhesion thickness of the retaining agent 4 is ½ or more of a single particle thickness of the nano-sized particles 3. .
(Supplementary Note 35) A magnetic recording apparatus comprising the magnetic recording medium according to any one of Supplementary Notes 1 to 17.
(Supplementary Note 36) A magnetic recording apparatus comprising the head slider according to any one of supplementary notes 18 to 34.
(Supplementary note 37) A magnetic recording apparatus comprising the magnetic recording medium according to any one of supplementary notes 1 to 17, and the head slider according to any one of supplementary notes 18 to 34.

  As an example of use of the present invention, a magnetic disk medium mounted on a perpendicular magnetic recording type magnetic disk apparatus corresponding to high recording density and a lubricant layer of a head slider are typical, but in-plane magnetization is used. The present invention is also applicable to a magnetic disk medium and a head slider mounted on a magnetic disk device of the in-plane magnetic recording type, and further applied to a magnetic tape or a lubricant layer of a magnetic head mounted on the magnetic tape device. Is.

It is explanatory drawing of the fundamental structure of this invention. 1 is a schematic cross-sectional view of a main part of a magnetic disk of Example 1 of the present invention. It is explanatory drawing of the relationship of the surface free energy of a fullerene molecule, a holding agent, and a protective film. It is explanatory drawing of the head slider of Example 2 of this invention. FIG. 6 is a conceptual plan view of a magnetic disk device according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outermost surface 2 Lubricating layer 3 Nanosize particle 4 Retaining agent 5 Retaining agent molecule 10 Magnetic disk 11 Glass substrate 12 Ta underlayer 13 CoZrNb backing layer 14 Ru intermediate layer 15 CoCrPt magnetic recording layer 16 Protective film 17 Lubricating layer 18 Fullerene molecule 19 Retaining Agent 20 Head Slider 21 Slider Body Part 22 Step Part 23 Positive Pressure Pad 24 Center Pad 25 Side Rail 26 Side Rail 27 Deep Groove Part 28 Groove Part 31 Al ₂ O ₃ Film 32 Lower Magnetic Shield Layer 33 Lower Gap Layer 34 Magnetoresistive Effect Element 35 Upper gap layer 36 Upper magnetic shield layer 37 Al ₂ O ₃ film 38 Main magnetic pole 39 Interlayer insulating film 40 Write coil 41 Auxiliary magnetic pole 42 Al ₂ O ₃ film 43 Protective film 44 Lubricating layer 51 Spindle motor 52 Disk clamp ring 53 Head Arm 54 suspension

Claims (6)

At least a part of the outermost surface has a lubricating layer made of nanosized particles having an average particle size of 0.53 nm to 1.05 nm made of a material having solid lubricating properties and a retaining agent containing the nanosized particles. Magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the nano-sized particles are either fullerene molecules or fullerene derivative molecules. When the surface free energy obtained from the Fowke equation of the retaining agent is γ _R and the surface free energy obtained from the Fowke equation of the base layer of the lubricating layer is γ _S ,
40 mN / m ≦ γ _R <γ _S
The magnetic recording medium according to claim 1, wherein the magnetic recording medium has the following relationship. A head slider provided with a magnetic head, wherein at least a part of the surface of the head slider has nano-sized particles having an average particle size of 0.53 nm to 1.05 nm made of a material having solid lubricity and the nano-sized particles. A head slider comprising a lubricating layer made of a contained retaining agent. When the surface free energy obtained from the Fowke equation of the holding agent is γ _R and the surface free energy obtained from the Fowke equation of the surface of the head slider is γ _H ,
40 mN / m ≦ γ _R <γ _H
The head slider according to claim 4, wherein: A magnetic recording apparatus comprising at least one of the magnetic recording medium according to any one of claims 1 to 3 and the head slider according to claim 4 or 5.

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