JPH08255338A - Magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a magnetic recording medium satisfying GHT characteristics, having a low surface friction coefficient, excellent durability, and having a uniform lubricant layer, and a method for producing the same. A magnetic material according to the present invention comprising a support, a magnetic layer provided on the support, a protective layer provided on the magnetic layer, and a lubricant layer provided on the protective layer. The recording medium is characterized in that the lubricant layer is formed from a polymer obtained by vapor phase polymerization of a fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic disk having a low friction coefficient and excellent durability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a magnetic recording medium such as a magnetic disk is lubricated on a magnetic layer or a protective layer provided on the magnetic layer in order to improve its durability. It has been widely practiced to provide an agent layer, but with the recent increase in recording density and the like, there is a demand for a magnetic recording medium that satisfies the glide height (GHT) characteristics and has further improved durability. .

Therefore, various proposals have been made in order to satisfy the above requirements, for example, a fluorine-based polymer is directly formed on the surface of a magnetic recording medium such as a magnetic disk by surface polymerization using a laser beam. , A method of forming a lubricant layer fixed to the surface has been proposed. However, since the lubricant layer formed by the above method is entirely adhered to the surface of the magnetic recording medium, the adhesion of the lubricant layer is improved, but the mobility of molecules constituting the lubricant layer is improved. It fell and did not satisfy the required durability.

Further, in the above surface polymerization, the polymerization reaction proceeds on the surface. Therefore, when the surface is microscopically nonuniform, the polymerization reaction also proceeds nonuniformly, and it is difficult to form a uniform lubricant layer. There is also the problem that In particular, it was difficult to obtain a lubricant layer having a large film thickness (for example, about 50 Å).

On the other hand, the lubricant layer is composed of a fixed layer and a free layer.
A method of improving durability as a layer structure has also been proposed, and when the thickness of the free layer is increased, the durability is improved to a required level. However, in this case, the surface roughness of the disk must be made small in order to realize an extremely low GHT, and as a result, the coefficient of friction of the lubricant layer becomes high, and the magnetic head is not used against the magnetic head when the magnetic recording medium is used. There is a problem of head adsorption.

Accordingly, an object of the present invention is to provide a magnetic recording medium having a uniform lubricant layer, which has a low surface friction coefficient and excellent durability while satisfying the GHT characteristics, and a method for producing the same. is there.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies for solving the above problems, the present inventors have found that a magnetic layer having a lubricant layer of a specific structure formed by using a specific compound in the coexistence of water. It has been found that a recording medium can achieve the above object.

The present invention has been made on the basis of the above findings, and includes a support, a magnetic layer provided on the support, a protective layer provided on the magnetic layer, and a protective layer provided on the magnetic layer. A magnetic recording medium comprising a lubricant layer provided on
A magnetic recording medium characterized in that the lubricant layer is formed from a polymer obtained by vapor phase polymerization of a fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr. Is.

Further, the present invention, as a preferred method for producing the above magnetic recording medium, includes a step of forming a lubricant layer by vapor-phase polymerizing a fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr. The present invention provides a method of manufacturing a magnetic recording medium including the above.

The magnetic recording medium of the present invention is useful as a magnetic drum, a magnetic tape or the like, and particularly useful as a magnetic disk such as a fixed disk.

The magnetic recording medium of the present invention will be described in detail below. As described above, the magnetic recording medium of the present invention includes a support, a magnetic layer provided on the support, a protective layer provided on the magnetic layer, and a lubricant provided on the protective layer. And layers.

As the support used in the present invention, either a magnetic support or a non-magnetic support can be used, but a non-magnetic support is generally used.
As the non-magnetic support, for example, carbon such as glassy carbon, tempered glass, crystallized glass, aluminum and aluminum alloys, titanium and titanium alloys, ceramics, resins, and supports made of composite materials thereof are used. . Among these, the support made of glassy carbon is particularly excellent in heat resistance, light weight and the like, and can be particularly preferably used in the present invention.

If desired, the support may be subjected to various texture treatments. Examples of such a texture treatment include treatment using a polishing tape or abrasive grains, etching treatment with an acid, thermal oxidation or anodization treatment,
Examples thereof include a process of depositing a silicate compound on the surface by spin coating, a plasma ashing process, a surface roughening process using a sputter texture for forming unevenness on the surface by sputtering a metal, and a sputter process.

In the present invention, examples of the magnetic layer provided on the support include a metal thin film type magnetic layer formed by PVD (Physical Vapor Deposition) means. Examples of the material for forming the metal thin film type magnetic layer include CoCr, CoNi, CoCrX, and Co.
NiX, CoWX (where X is Ta, Pt, Au,
Ti, V, Cr, Ni, W, La, Ce, Pr, Nd,
Pm, Sm, Eu, Li, Si, B, Ca, As, Y,
Zr, Nb, Mo, Ru, Rh, Ag, Sb, and Hf are one or two or more kinds selected from the group consisting of) and the like, and a Co-based magnetic alloy containing Co as a main component is preferable. Among them, they can be used alone or as a mixture of two or more kinds. The thickness of the magnetic layer is preferably 20 to 50 nm, but is not limited to this range.

In the present invention, the protective layer provided on the magnetic layer is, for example, a layer formed by PVD, spin coating, or the like, and is formed of a material having high mechanical strength from the viewpoint of abrasion resistance. Is preferred. Examples of the material for forming the protective layer include Al, Si,
Oxides of metals such as Ti, Cr, Zr, Nb, Mo, Ta, W (silicon oxide, zirconium oxide, etc.); nitrides of the metal (boron nitride, etc.); carbides of the metal (silicon carbide,
Tungsten carbide and the like); one or more selected from the group consisting of carbon such as diamond-like carbon or boron nitride and the like is used. Among the above materials, carbon, silicon carbide, tungsten carbide, silicon oxide, zirconium oxide, boron nitride or a composite material thereof is preferable, carbon is more preferable, and diamond-like carbon is particularly preferable. The thickness of the protective layer is preferably 5 to 25 nm, but is not limited to this range.

Thus, the magnetic recording medium of the present invention is obtained by vapor phase polymerization of a fluorocarbon compound and oxygen in the presence of the lubricant layer provided on the protective layer in the presence of water of 1 to 10 Torr. It is characterized in that it is formed from the polymer.

During the above gas phase polymerization, the reaction system contains 1 to 10 To.
The coexistence of water of rr makes it possible to increase the film thickness of the lubricant layer formed, and also facilitates control of the film thickness, further improving productivity. The amount of water is 1 Tor
If it is less than r, the thickness of the film formed in one step is thin and inefficient, and if it exceeds 10 Torr, the film is excessively formed and the uniformity of the film thickness is deteriorated. The preferred amount of water is 2 to 6 Torr.

The ratio of the fluorocarbon compound to oxygen used is preferably the fluorocarbon compound / oxygen (molar ratio) of 1 / 0.5 to 1/100, more preferably 1/1.
˜1 / 10, most preferably ½˜1 / 8. If the use ratio is lower than 1/100, the absorption efficiency of laser light or the like decreases, and the polymerization cannot be said to be sufficient. It is preferable to set the inside.

The above-mentioned polymer of the fluorocarbon compound and oxygen is a polymer mainly having a-(CF ₂ O)-structural unit, and its molecular weight is preferably 500 to 3000.
0. Although the structure of the above polymer is not completely known, for example, a polymer represented by the following structural formula is estimated. X- (CF ₂ O) _l- (CF ₂ CF ₂ O) _m- (CF ₂ CF ₂ CF ₂ O) _n -X '[wherein l, m and n are the same or different positive integers] (Provided that l >> m, l >> n), X and X'represent the same or different CF ₃ O, CF ₃ or alcohol or an ether bond, an ester bond, a urethane bond, or the like. ]

The above-mentioned (-CF ₂ O) -in the above-mentioned polymer.
The content of the structural unit is preferably 70% or more in all structural units. For example, in the polymer represented by the above structural formula, [l / (l + m + n)] × 100 is 70% or more. Is preferred.

In the present invention, the lubricant layer preferably comprises a fixed layer fixed on the protective layer and a free layer formed on the fixed layer. Here, the fixed layer is a layer which is firmly fixed chemically or physically to the protective layer and which is not washed off even if it is washed with a fluorine-based solvent such as a trade name “CFC113”. The free layer is a layer that is washed away when washed with the fluorine-based solvent.

The thickness of the fixed layer and the thickness of the free layer depend on the number of times the gas phase polymerization is performed. Therefore, in order to obtain the fixed layer and the free layer having a desired thickness, the number of times of performing the gas phase polymerization may be adjusted. As for the ratio of the thickness (weight) of the fixed layer to the thickness (weight) of the free layer, the thickness (weight) of the free layer / the thickness (weight) of the fixed layer is preferably 1 / 10 to 10/1, more preferably 2/5 to 5/1
Is. The fixed layer preferably has a thickness of 5 to 30 Å. If the thickness is less than 5Å, the abrasion resistance is poor and the durability is poor, and if it exceeds 30Å, the structure of the film is disturbed and the abrasion resistance is deteriorated again. The thickness of the free layer is preferably 2 to 80Å. If the thickness is less than 2Å, durability is poor and
If it exceeds 0Å, the coefficient of friction increases, so it is preferable to set it within the above range.

As described above, when the lubricant layer in the magnetic recording medium of the present invention is composed of the fixed layer and the free layer, the thickness of the free layer is set to the conventional free layer (8 The thickness of the free layer in the present invention is larger than the thickness of the free layer in the conventional magnetic recording medium because the coefficient of friction of the surface of the magnetic recording medium does not increase even if the thickness is larger than 20 Å). can do.

The thickness of the lubricant layer (including the case where the lubricant layer is composed of the fixed layer and the free layer) is preferably 5 to 200 Å, but if it is 10 to 100 Å, the lubricating effect is high. It is particularly preferable because the spacing loss can be suppressed. It is more preferable that the thickness of the lubricant layer is 20 to 80 Å, particularly 20 to 50 Å because the above effect becomes remarkable. If the thickness exceeds 200Å, the spacing loss increases, and if the thickness is less than 5Å, the lubricating effect becomes poor. Therefore, it is preferably within the above range.

As the above-mentioned fluorocarbon compound, in particular,
It is preferable to use a compound having a carbon-carbon double bond, and above all, the fluorocarbon compound is represented by the following general formula (I).
Preferably selected from the group consisting of compounds represented by CF ₂ = CFR _f ¹ ... (I) (In the formula, R _f ¹ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, or perfluoroaryl. Group or a partially fluorinated aryl group) CF ₂ ═C (R _f ² ) (R _f ³ ) ... (II) (In the formula, R _f ² and R _f ³ are the same or different hydrogen atoms. , A fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group or a partially fluorinated aryl group) CF ₂ ═CFO (R _f ⁴ ) ... · (III) (In the formula, R _f ⁴ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group, a moiety. Represents a fluorinated aryl group or a perfluoroalkoxyalkyl group)

The above fluorocarbon compounds may be used alone or in admixture of two or more.
When two or more kinds are used, two or more kinds may be selected and used from any one of the general formulas (I) to (III), or among the general formulas (I) to (III). One or more types may be selected from at least two categories and used.

In the above general formula (I), preferable perfluoroalkyl groups are perfluoromethyl group (CF ₃ —) and perfluoroheptyl group (C ₅ F ₁₁ —).
And perfluorohexyl group (C ₆ F ₁₃ -) can be mentioned; Preferred perfluoroalkenyl group, perfluoro ethynyl group (CF ₂ = CF-) are exemplified; Preferred partially fluorinated alkyl group, 1H- perfluorobutyl group (C ₄ F ₈ H-) can be mentioned; preferred partially fluorinated alkenyl group, -CF ₂ -CF =
CH ₂ may be mentioned; a preferred perfluoroaryl group is a perfluorobenzyl group (—CF ₂ —C ₆ F ₅ ).
It can be mentioned; and Preferred partially fluorinated aryl group, -CFH-C ₆ F ₅ and -CF ₂ -C ₆ H ₅
Is mentioned.

Therefore, the compound represented by the general formula (I)
Of these, tetrafluoroethylene is preferable.
(CF₂= CF₂), Hexafluoropropene (CF₂=
CFCF₃), Perfluoroheptene-1 (CF₂= CF
C_FiveF₁₁), 6H-perfluorohexene-1 (CF₂
= CFC_FourF₈H), perfluorooctene-1 (CF
₂= CFC₆F₁₃), Hexafluoro-1,3-butadi
EN (CF₂= CF CF = CF₂), 3- (pentafluor
Rophenyl) pentafluoropropene-1 (CF₂= C
FCF₂C₆F_Five), CF₂= CFCHF-C₆F_Five, C
F₂= CFCF ₂-C₆H_Five, CF₂= CFCF₂CF
= CH₂Etc.

In the above general formula (II), preferred perfluoroalkyl groups include CF ₃ CF ₂ — in addition to those in the above general formula (I); preferred perfluoroalkenyl groups include the above general formula ( In addition to those in I), mention may be made of —CF ₂ —CF═CF ₂ ; preferred partially fluorinated alkyl groups are —CF ₂ H and —.
CF ₂ CF ₂ H is included; preferred partially fluorinated alkenyl groups include —CF═CH _{2 in} addition to those in the above general formula (I); and preferred perfluoroaryl groups and partially fluorinated aryl groups. as,
The same thing as the thing in the said General formula (I) is mentioned.

Therefore, the compound represented by the general formula (II)
Of these, CF is preferable. ₂= C (CF₃)₂,
CF₂= CH₂, CF₂= CHF, CF₂= CHC
F₃, CF₂= CHCF₂CF₃, CF₂= CHCF =
CF₂, CF₂= CHCF₂CF = CF₂, CF₂= C
HCF₂H, CF₂= CHCF₂CF₂H, CF₂= C
HCF₂CF = CH₂, CF₂= CHCF = CH₂, C
F₂= CHCFH-C₆F _Five, CF₂= CHCF₂-C
₆H_FiveEtc.

In the above general formula (III), preferable perfluoroalkyl groups and perfluoroalkenyl groups are the same as those in the above general formula (II); preferred partial fluorinated alkyl groups are:
CF ₂ H, —CF ₂ CF ₂ H and —C ₄ F ₈ H may be mentioned; preferred partially fluorinated alkenyl groups, perfluoroaryl groups and partially fluorinated aryl groups are those in the above general formula (II). like can be mentioned; and, as the preferred perfluoro alkoxyalkyl _{group, -CF 2 CF (CF 3)} OC 3 H 7 and the like.

Therefore, the compound represented by the general formula (III)
Of these, CF is preferable. ₂= CFOCF₃,
CF₂= CFOC_FiveF₁₁, CF₂= CFOC₆F₁₃, C
F₂= CFOCF₂CF₃, CF₂= CFOCF = CF
₂, CF₂= CFOCF₂CF = CF₂, CF₂= C_Four
F₈H, CF₂= CFOCF₂H, CF₂= CFOCF
₂CF₂H, CF₂= CFOCF₂-CF = CH₂, C
F₂= CFOCF = CH₂, CF₂= CFOCF₂-C
₆F_Five, CF₂= CFOCFH-C₆H_Five, CF₂= C
FOCF₂-C₆H_Five, CF₂= CFOCF₂CF (C
F₃) OC₃H₇Etc.

In the magnetic recording medium of the present invention, an underlayer may be formed between the support and the magnetic layer. The underlayer can be provided by PVD means such as sputtering using Cr, Ti, Al or alloys thereof. The thickness of the underlayer is preferably 10 to 100 nm, but is not limited to this range.

Next, a preferable method for manufacturing the magnetic recording medium of the present invention will be described. The magnetic recording medium of the present invention is 1
It is preferably produced by a method including a step of vapor-phase polymerizing a fluorocarbon compound and oxygen in the coexistence of water of 10 Torr to form a lubricant layer.

The gas phase polymerization is carried out in a system in which the fluorocarbon compound and oxygen are kept in a gas state in the gas state in the coexistence of water of 1 to 10 Torr, and the polymerization reaction is performed only in the gas phase. Means the polymerization method that results. As a method that can be adopted for the polymerization, for example, plasma polymerization or CVD such as photo CVD (chemical vapor deposition) can be adopted. In the present invention, vapor phase polymerization by photo-CVD is preferably used because the equipment and facilities are simple.

When the vapor phase polymerization is carried out by the photo-CVD, the surface of the object to be deposited (that is, the surface of the protective layer) is not directly irradiated with laser light, but is irradiated only in the raw material gas. Is preferred.

At this time, examples of the light source that can be used include ultraviolet rays and infrared rays. For the reasons described below, it is preferable to use ultraviolet rays. Specifically, for example, excimer laser light of 193 nm is preferably used. be able to. That is, the reaction by the infrared laser using the infrared light source is basically a reaction by vibrational excitation, and is essentially the same as the thermal reaction, and a side reaction occurs to generate a product other than the target product, It has a drawback that it is difficult to control the structure of the formed film. On the contrary,
An ultraviolet laser using an ultraviolet ray as a light source causes a polymerization reaction by electronic excitation, has good reaction selectivity, and further, since the involvement of a thermal reaction is extremely low, a side reaction is unlikely to occur. It has no such drawbacks.

The temperature of the support (provided with the protective layer) at the time of carrying out the gas phase polymerization is preferably set to 10 to 90 ° C., more preferably 15 to 50 ° C. If the content is out of the above range, the lubricant layer may not be formed. Therefore, the content is preferably in the above range.

The pressure of the fluorocarbon compound introduced into the system is preferably 0.5 to 50 Torr, more preferably 1 to 20 Torr. On the other hand, the pressure of oxygen introduced into the system is preferably 1 to 150 Torr, more preferably 3 to 70 Torr.

The above steps may be carried out only once, or may be carried out a plurality of times if necessary. Particularly preferably, as described below, at least two steps of the first polymerization step and the second polymerization step are performed.

That is, in the above manufacturing method, particularly preferably, a first polymerization step of forming a lubricant layer by vapor-phase polymerizing the fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr, After evacuating the reaction system, 1 to 10 To
The second polymerization step of vapor-phase polymerizing the fluorocarbon compound and oxygen in the presence of rr of water to form a lubricant layer is sequentially performed. By performing such a step, it becomes easier to form the lubricant layer including the fixed layer and the free layer.

Here, the first polymerization step is a step of mainly forming the fixed layer, and the second polymerization step is a step of mainly forming the free layer. That is, the free layer may be formed in the first polymerization step, and the fixed layer may be formed in the second polymerization step.

Next, the above first and second polymerization steps will be described more specifically with reference to FIG. Here, FIG. 1 is a schematic view showing a photoreaction chamber that is preferably used in manufacturing the magnetic recording medium of the present invention.

The photoreaction chamber 1 shown in FIG. 1 is provided with a laser transmission window 2 provided on both left and right side surfaces above it for transmitting laser light, and a magnetic disk support as a magnetic recording medium provided below the laser transmission window 2. 3 (provided up to the protective layer) is provided with a medium setting member 4 capable of standing upright at regular intervals, and a valve 5 provided on the upper part for decompressing the inside of the chamber and releasing the atmosphere.

In the first polymerization step, first, the valve 5 is opened and the chamber 1 is connected to a vacuum pump (not shown), and the inside of the chamber 1 is depressurized (preferably, preferably). After 1 × 10 ^{−5 to} 1 Torr, particularly preferably 1 × 10 ^{−2 to} 0.1 Torr, the chamber 1 is filled with 1 to 10 Torr (preferably 2 to 10 Torr).
Water of 6 Torr) is introduced, and further, the fluorocarbon compound (preferably 1 to 20 Torr) and oxygen (preferably 3 to 70 Torr) are introduced to make a vacuum condition. Next, excimer laser light or the like is irradiated in the direction of the arrow shown in FIG. 1 so as to pass through the center between the upper part of the magnetic disk support 3 and the chamber ceiling and not hit the magnetic disk support 3. Here, the vacuum condition is preferably 1 ×
10 ^{−5 to} 1 Torr (particularly preferably 1 × 10 ^{−2 to} 0.
It means a state in which 1 to 10 Torr (preferably 2 to 6 Torr) of water, the fluorocarbon compound (preferably 1 to 20 Torr) and oxygen (preferably 3 to 70 Torr) are introduced into a reaction vessel of 1 Torr). The pressure in the chamber 1 in this state is preferably 5 to 200 Torr, more preferably 10 to 10
It is 0 Torr. The medium mounting member 4 can rotate each magnetic disk support 3 in the circumferential direction (direction of arrow D in FIG. 1).

The above first polymerization step may be repeated several times.

Next, in the second polymerization step, after the completion of the first polymerization step, the chamber 1
The interior is evacuated and the reaction system is evacuated (preferably 1 × 10 ⁻⁵ to 1).
Torr, particularly preferably 1 × 10 ^{-2 to} 0.1 Tor
r) and then 1-10 Torr (preferably 2-6T)
orr) water is further introduced, and further the fluorocarbon compound (preferably 1 to 20 Torr) and oxygen (preferably 3 to 70 Torr) are introduced to make a vacuum condition, and the excimer laser light or the like is irradiated. Here, the “vacuum condition” in the second polymerization step is also the same as the “vacuum condition” in the first polymerization step.

The above second polymerization step may also be repeated several times. Furthermore, after the above second polymerization step,
It is possible to carry out the above first polymerization step again, or
It is also possible to carry out the third polymerization step, the fourth polymerization step, and the like.

The fluorocarbon compounds introduced into the chamber 1 in the first and second polymerization steps may be the same or different. Particularly, when the fluorocarbon compound used in the first polymerization step is a compound represented by the general formula (I), the fluorocarbon used in the second polymerization step is used. The system compound is also preferably a compound represented by the above general formula (I). Similarly, when the fluorocarbon compound used in the first polymerization step is a compound represented by the general formula (II) or (III), it is used in the second polymerization step. The above-mentioned fluorocarbon-based compound is also preferably a compound represented by the above general formula (II) or (III). Most preferably, the fluorocarbon-based compounds used in the first and second polymerization steps are the same.

In a particularly preferred method for producing the magnetic recording medium of the present invention, the magnetic recording medium having a lubricant layer formed on the magnetic layer by vapor phase polymerization is used in an amount of 30 to 100.
Let stand for 1 hour or more at 50 ° C. and 50 to 98% RH. By manufacturing a magnetic recording medium using such a method, the reduction in the thickness of the lubricant layer and the reduction in CSS durability were suppressed even when the magnetic recording medium was left under high temperature and low humidity, which is a severe environment for the magnetic recording medium. A magnetic recording medium is obtained. Furthermore, by forming the lubricant layer by photo-CVD, it is possible to further suppress the decrease in the thickness of the lubricant layer and the decrease in CSS durability.

The above method will be described in more detail. First, a magnetic recording medium in which a lubricant layer is formed on a magnetic layer by gas phase polymerization is manufactured. Then, the magnetic recording medium is set to 30 to 100.
An aging step is performed in which it is left at 50 ° C. and 50 to 98% RH for 1 hour or more. This makes it possible to suppress a decrease in the thickness of the lubricant layer even under high temperature and low humidity, which is a severe environment for the magnetic recording medium. If the temperature is lower than 30 ° C., only the same performance as that without aging can be obtained, and if it exceeds 100 ° C., a decrease due to scattering of the lubricant layer occurs during aging. Also, if the relative humidity is less than 50%, only the performance equivalent to that without aging is obtained, and 98%
If it exceeds, the water content will condense on the surface of the magnetic recording medium and the performance will be deteriorated. Further, if the time for leaving is less than 1 hour, the effect of aging may not be obtained, so it is preferable to leave for 1 hour or more.

Although there is no particular limitation on the standing time after the formation of the lubricant layer until the aging, it is preferable to perform the aging at an early stage, for example, within one week after the formation of the lubricant layer.

The atmosphere of the aging is not particularly limited. Generally, it is easy to perform aging in air. Aging is preferably performed in an atmosphere of an inert gas such as nitrogen or helium.

The aging is more preferably 40 to
It is carried out at 70 ° C. and 60 to 80% RH for 3 to 12 hours, and more preferably at 40 to 70 ° C. and 60 in an inert gas atmosphere.
Perform at -80% RH for 3-12 hours.

When performing the aging, the temperature and humidity are gradually raised from the ambient temperature and humidity to the target temperature and humidity, and when the target temperature and humidity are reached, they are left for a predetermined time. After standing for a predetermined time, it is preferable to gradually lower the temperature and the humidity and return to the ambient temperature and the humidity. In this case, the temperature increase and the humidity increase may or may not be linked. For example, only the temperature may first reach the target value, and then the humidity may reach the target value. Similarly, the drop in temperature and the drop in humidity may or may not be linked.

The aging may be carried out only once, or may be carried out a plurality of times if necessary.

With respect to the steps other than the formation of the lubricant layer, the same method as a conventionally known method for manufacturing a magnetic recording medium can be adopted without any particular limitation.

[0058]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 A support made of glassy carbon having a density of 1.5 g / cm ³ (size 1.8 inch, thickness 2)
5 mil) 11 is polished and the center line average roughness Ra is 1.0 n
It was set to m. After that, texture processing (Al-Si alloy sputtering) was performed to set the center line average roughness Ra to 15 Å. Then, the underlayer 12 made of Cr and having a thickness of 50 nm is formed in the Ar gas atmosphere by DC magnetron sputtering to form the support 1
1 and then a 40 nm thick CoCrTa-based magnetic layer 13 was provided. Subsequently, using a facing target type sputtering apparatus equipped with a glassy carbon target, the interior of the chamber was evacuated, and Ar gas was introduced so that the gas pressure was 2 mTorr, and sputtering was performed.
Protective layer 14 consisting of 200Å thick glassy carbon on top
And a magnetic disk support 3 was obtained.

Using the magnetic disk support 3 thus obtained,
As shown in FIG. 1, the photo-reaction chambers 1 shown in FIG. 1, which are photo-CVD apparatus, are arranged in parallel as shown in FIG. 1 at a predetermined interval, and the inside of the chamber 1 is 5 × 10 ⁻² Torr.
After exhausting to 2 torr, water was introduced at 2 Torr, then tetrafluoroethylene (CF ₂ = CF ₂ ) 10 Torr and oxygen 60 T
orr and the ArF excimer laser (wavelength 193
laser beam (power 150 mJ, repetition rate 2 Hz) from 1 nm) was irradiated for 1500 pulses over 12.5 minutes, and the first polymerization step was performed once. The laser light was irradiated in the direction of the arrow shown in FIG. 1 so as not to directly irradiate the magnetic disk support 3. The temperature of the magnetic disk support 3 was room temperature (22 ° C.) during the photo-CVD.

Then, the chamber 1 is evacuated to 5 × 1.
After a vacuum of 0 ^-2 Torr, the second polymerization step was performed once under the same conditions as the first polymerization step.

Thus, the magnetic disk as the magnetic recording medium 10 shown in FIG. 2, that is, the support 11, the underlayer 12 provided on the support 11, and the underlayer 12 are provided. The magnetic layer 13, the protective layer 14 provided on the magnetic layer 13, and the lubricant layer 15 provided on the protective layer 14, the lubricant layer 15 being the protective layer 14 of the protective layer 14. A fixed layer 15a having polymer molecules fixed to the surface by chemical bonds, and a free layer 15 formed on the fixed layer 15a.
A magnetic disk consisting of b and b was obtained.

The fact that the lubricant layer 15 is composed of the fixed layer 15a and the free layer 15b was confirmed by the following and. The above magnetic disk was ultrasonically cleaned with Freon 113 for 10 minutes and checked for weight change. After the above washing, ESCA (E manufactured by VG Science Co., Ltd.
SCALAB200C, using AlKα ray) was analyzed to confirm the presence or absence of residual molecules of the polymer on the surface of the magnetic disk. Also, according to ESCA analysis of the lubricant layer, Cls
A peak was observed around 294.7 eV, which is the C of the (CF ₂ O) _n unit in the database prepared using a commercially available purple oropolyether lubricant.
Since consistent with ls spectrum, lubricant molecules primarily - (CF ₂ O) _n - was found to be those having a structural unit. Incidentally, since the small peak in the vicinity 292,289eV is observed - believed also coexist small amounts structural units other than structural units of - (CF ₂ O) _n.

[Examples 2 to 17] Magnetic disks each having the structure shown in FIG. 2 were obtained in the same manner as in Example 1 except that the photo-CVD treatment of Example 1 was performed under the conditions shown in Table 1.

[0065]

[Table 1]

Comparative Example 1 A magnetic disk was manufactured according to Example 1 described in JP-A-4-186524. That is, the Ni-P plated Al support was subjected to the texture treatment according to Example 1 and the underlayer, the magnetic layer and the protective layer were formed to obtain a magnetic disk support 3. The magnetic disk support 3 is placed in a chamber and evacuated, and then a mixed gas of hexafluoropropene and oxygen (1:
1) was introduced at 100 Torr, and an ArF excimer laser (wavelength 193 nm) was directed toward the magnetic disk support 3.
Laser light (power 150mJ, repetition rate 2H
z) was irradiated to form a lubricant layer to obtain a magnetic disk.

Comparative Example 2 A magnetic disk was manufactured according to Example 5 described in JP-A-6-220185. That is, the Ni—P plated Al support was subjected to the texture treatment according to Example 1 and the underlayer, the magnetic layer and the protective layer were formed to obtain a magnetic disk support. This magnetic disk support was placed in a chamber, cooled to -50 ° C., and evacuated, and a mixed gas of CF ₂ CF = CF ₂ and oxygen (3: 1) was introduced at 100 Torr, or at 1 Torr.
Introducing a CF ₃ OCF _3, carbon dioxide laser (wavelength 1020-1
A laser beam (power: 300 mJ, repetition rate: 0.7 Hz) from 060 cm ⁻¹ ) was irradiated for 12 minutes to form a lubricant layer to obtain a magnetic disk.

Comparative Example 3 A magnetic disk was manufactured according to Example 3 described in Japanese Patent Laid-Open No. 5-174354. That is, the Ni—P plated Al support was subjected to the texture treatment according to Example 1 and the underlayer, the magnetic layer and the protective layer were formed to obtain a magnetic disk support. This magnetic disk support was used as a perfluoropolyether lubricant (“Fomblin AM200” manufactured by Montecatini Co.).
l ", trade name). After this, it was taken out, set in a box-shaped chamber equipped with a low-pressure mercury lamp (150 W), evacuated, then introduced with 10 Torr hexafluoroethane and 10 Torr fluorine, and further introduced with 3 Torr perfluoropropene, A laser beam (power 150 mJ, repetition rate 2 Hz) from an ArF excimer laser (wavelength 193 nm) was condensed and irradiated through a quartz lens, induction destruction was performed for 5 minutes, and radical treatment was performed to obtain a magnetic disk. During this period, the low pressure mercury lamp was turned on and the magnetic disk was directly irradiated.

[Comparative Example 4] A magnetic disk was manufactured in accordance with Example 1 described in JP-A-4-311812. That is, the magnetic disk support 3 similar to that of the first embodiment.
A solution of a perfluoropolyether-based lubricant (“DemunmSP”, trade name, manufactured by Daikin Industries, Ltd.) having an active group is applied by a dip coating method and then at 150 ° C. for 3 days.
Heat treatment was performed for 0 minutes. After cooling, ultrasonic cleaning was performed with a fluorine-based solvent for 10 minutes. After that, a chemically inert perfluoropolyether lubricant (“DeK” manufactured by Daikin Industries, Ltd.
mnumS-100 ", trade name) was applied by a dip coating method to form a lubricant layer, and a magnetic disk was obtained.

[Comparative Example 5] A magnetic disk was manufactured according to Example 1 described in JP-A-3-104015. That is, the Ni—P plated Al support was subjected to the same texture treatment as in Example 1 and the underlayer, magnetic layer and protective layer were formed to obtain a magnetic disk support. This was set in the chamber, and after vacuum evacuation, 5 Torr of tetrafluoromethane was introduced, carbon dioxide infrared laser light was condensed by a lens, and the magnetic disk support was irradiated to form a lubricant layer, I got a magnetic disk.

Comparative Example 6 A magnetic disk was manufactured according to Example 1 described in JP-A-2-81319. That is, the Ni—P plated Al support was subjected to the texture treatment according to Example 1 and the underlayer, the magnetic layer and the protective layer were formed to obtain a magnetic disk support. After setting this in the chamber and evacuating it, 0.05 Tor
r methane is introduced, and 10 is applied to the magnetic disk support.
A high frequency power source of 00 W was connected, ethylene tetrafluoride was introduced to achieve 0.3 Torr, and the voltage was drastically reduced to 5 W to form a lubricant layer to obtain a magnetic disk.

[Performance Evaluation] With respect to the magnetic disks obtained in Examples 1 to 17 and Comparative Examples 1 to 6, respectively,
The thickness of the lubricant layer and the thickness of the free layer and the thickness of the fixed layer were measured. The results are shown in Table 2. The CSS durability and GHT characteristics of the obtained magnetic disk were measured by the methods described below. The results are also shown in Table 2.

<CSS Durability> Using a thin film head manufactured by Yamaha Corporation, a head load of 3.5 g, a head flying height of 2.8 μ inches, movable for 5 seconds at 4500 rpm, and stopped for 5 seconds were repeated 20,000 times. The static friction coefficient at that time was measured.

<GHT characteristics>"MG" manufactured by PROQUIP
150T "and a 50% slider head were used for the test. In this case, a flying height of 1.2 μ inches having a passing rate of 90% or more was S, and a passing rate of 50 to 90% was A. And those having a passage rate of 40% or less were designated as B.

[0075]

[Table 2]

As is clear from the results shown in Table 2, the magnetic recording media of the present invention (Examples 1 to 17) satisfy the extremely strict GHT characteristic of 1.2 μ inch and C
It can be seen that it has excellent SS durability. That is, the magnetic recording medium of the present invention can reduce the spacing loss between the head and the magnetic layer, is excellent in electromagnetic conversion characteristics, and is also excellent in durability. On the other hand, it can be seen that the magnetic disk having the lubricant layer formed by CVD surface polymerization (Comparative Example 1) also has unevenness in the lubricant layer and has poor GHT characteristics. Further, in the magnetic disk in which the lubricant layer was formed without introducing water into the reaction system during the photo-CVD (Comparative Example 2), it was found that the lubricant layer had uneven thickness and the GHT characteristics were poor. Further, it is understood that the CSS durability is poor in the magnetic disk (Comparative Example 3) in which the lubricant layer is formed by applying a lubricant and then performing plasma treatment and ultraviolet irradiation. Further, it is found that even if the lubricant layer including the fixed layer and the free layer is formed, the magnetic disk having the lubricant layer formed by the immersion / plasma treatment method (Comparative Example 4) has poor CSS durability. Further, it can be seen that even the magnetic disks having the lubricant layer formed by treating the surface of the protective layer with fluorine radicals (Comparative Examples 5 and 6) have poor CSS durability.

[0077]

The magnetic recording medium of the present invention has a low surface friction coefficient and excellent durability while satisfying the GHT characteristics. Further, the lubricant layer having a large film thickness can be formed by one operation, and the film thickness can be easily controlled. Further, according to the method for manufacturing a magnetic recording medium of the present invention,
The magnetic recording medium of the present invention can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a schematic view showing a photoreaction chamber that is preferably used when manufacturing a magnetic recording medium of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of a magnetic recording medium of the present invention.

[Explanation of reference numerals] 1 chamber 2 laser transmission window 3 magnetic disk support 4 medium installation member 5 valve 10 magnetic recording medium 11 support 12 underlayer 13 magnetic layer 14 protective layer 15 lubricant layer 15a fixed layer 15b free layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C09D 127/12 PFH C09D 127/12 PFH 129/10 PFP 129/10 PFP G11B 5/84 7303-5D G11B 5/84 A

Claims (7)

[Claims] 1. A magnetic recording comprising a support, a magnetic layer provided on the support, a protective layer provided on the magnetic layer, and a lubricant layer provided on the protective layer. In the medium, the lubricant layer is formed from a polymer obtained by vapor phase polymerization of a fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr. 2. The magnetic recording medium according to claim 1, wherein the lubricant layer comprises a fixed layer fixed on the protective layer and a free layer formed on the fixed layer. Wherein said polymer is predominantly - (CF ₂ O)
The magnetic recording medium according to claim 1, which has a structural unit of-. 4. The magnetic recording medium according to claim 1, wherein the fluorocarbon compound is selected from the group consisting of compounds represented by the following general formulas (I) to (III). . CF ₂ = CFR _f ¹ ... (I) (In the formula, R _f ¹ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, or perfluoroaryl. Group or a partially fluorinated aryl group) CF ₂ ═C (R _f ² ) (R _f ³ ) ... (II) (In the formula, R _f ² and R _f ³ are the same or different hydrogen atoms. , A fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group or a partially fluorinated aryl group) CF ₂ ═CFO (R _f ⁴ ) ... · (III) (In the formula, R _f ⁴ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group, a moiety. Represents a fluorinated aryl group or a perfluoroalkoxyalkyl group) 5. The method of manufacturing a magnetic recording medium according to claim 1, wherein the fluorocarbon compound and oxygen are vapor-phase polymerized in the coexistence of water at 1 to 10 Torr to lubricate the medium. A method of manufacturing a magnetic recording medium, comprising the step of forming an agent layer. 6. A first polymerization step of forming a lubricant layer by vapor-phase polymerizing the fluorocarbon compound and oxygen in the coexistence of water of 1 to 10 Torr, and after evacuating the reaction system, 1
The method according to claim 5, wherein the second polymerization step of vapor-phase polymerizing the fluorocarbon compound and oxygen in the coexistence of water of 10 Torr to form a lubricant layer is performed sequentially. 7. The magnetic recording medium according to claim 1, wherein the fluorocarbon compound is selected from the group consisting of compounds represented by the following general formulas (I) to (III). . CF ₂ = CFR _f ¹ ... (I) (In the formula, R _f ¹ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, or perfluoroaryl. Group or a partially fluorinated aryl group) CF ₂ ═C (R _f ² ) (R _f ³ ) ... (II) (In the formula, R _f ² and R _f ³ are the same or different hydrogen atoms. , A fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group or a partially fluorinated aryl group) CF ₂ ═CFO (R _f ⁴ ) ... · (III) (In the formula, R _f ⁴ is a fluorine atom, a perfluoroalkyl group, a perfluoroalkenyl group, a partially fluorinated alkyl group, a partially fluorinated alkenyl group, a perfluoroaryl group, a moiety. Represents a fluorinated aryl group or a perfluoroalkoxyalkyl group)