JP2002275484A - Lubricant containing phosphazene compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant for a hard disk having excellent CSS durability. SOLUTION: This lubricant contains phosphazene compounds represented by general formulas (1) A-OCH2 CF2 O(CF2 CF2 O)p (CF2 O)q CF2 CH2 O-A and (5) A-[OCH2 CF2 O(CF2 CF2 O)p (CF2 O)q CF2 CH2 OH]6-z composed of a sequence in which a perfluoroxyalkylene unit selected from -CF2 O- and -CF2 CF2 O- is randomly distributed and which contains functional terminal group A's [A is a group represented by formula (a) ; R is a hydrogen atom, a 1-4C alkyl, a 1-4C alkoxy, a 1-4C haloalkyl, an aryl, a substituted aryl, an aryloxy or a substituted aryloxy; p and q are each a real number of 1-30; and z is an integer of 1-5].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a lubricant containing a phosphazene compound. More specifically, the present invention relates to a lubricant for a recording medium such as a hard disk as a large-capacity recording medium or a metal-deposited tape used for an 8 mm video tape recorder or a digital video cassette.

[0002]

2. Description of the Related Art With the spread of the Internet, intranets, local area networks, and the like, information can be easily retrieved simply by accessing a network. One of the things that support the multimedia age is an external storage device. As an existing large-capacity external storage device, a recording medium layer is provided on a high-strength circular substrate (hard disk), and the hard disk is rotated at high speed to operate a recording / reproducing element (head), that is, a so-called CSS system. A hard disk includes a fixed magnetic disk, an optical disk, a magneto-optical disk, and the like. The most popular of these is an apparatus using a fixed magnetic disk.

[0003]

In order to increase the capacity without changing the size of these external storage devices, it is necessary to increase, for example, the areal recording density of a recording medium layer. To do this,
It is necessary to reduce the bit size and move the head as close to the recording medium as possible. In order to reduce the distance between the head and the disk, the irregularities on the disk surface must be reduced. For example, to reduce the distance to 100 nm or less, the irregularities must be reduced to 10 nm or less. When the smoothness of the disk surface is improved, on the other hand, the head is more easily attracted to the disk surface. Also, in order to obtain high-speed response, it is necessary to increase the bit transfer speed and, consequently, the rotation speed of the disk. For example, the maximum rotation speed of a 3.5-inch hard disk needs to be 5400 to 7200 rpm, and the head passing speed around the disk reaches 125 km / hr. However, any of the above changes greatly increases the probability of contact between the disk and the head, abrasion, etc., and lowers reliability.

To cope with these problems and protect the disk surface and the head, it is easiest to increase the amount of lubricant applied to the disk protective film surface. However, when the amount of the applied lubricant is increased, not only the sliding resistance of the lubricating film is increased, but also the action of adsorbing the lubricant is increased, and the spindle motor stops and burns. If a low-viscosity lubricant is used to reduce the sliding resistance, the lubricant moves and disappears from the protective film when the disk rotates at a high speed, causing contact between the disk and the head and breakage.

[0005] The lubricant can be formed very simply by forming a lubricant film having a uniform molecular thickness on a protective film provided on the hard disk so that the lubricant can be used when the hard disk rotates and when the apparatus is started up.
Friction and abrasion generated at the time of stopping are reduced. To protect the disk and head, the sliding resistance is low, the bonding strength with the protective film is large, the coefficient of friction is low, the chemical stability, thermal stability, corrosion resistance are large, and the temperature is low at -10 ° C or lower. A lubricant having a lubricating ability and capable of forming an ultrathin film at a low vapor pressure is required. The hard disk lubricant has a CSS durability of 50,000 times or more and has no change in friction coefficient. That is, in the CSS repetition test, it is required that there is no abnormality such as burn-in of the head and scratches on the disk at least up to 50,000 times.

For protecting the surface of the current hard disk, a diamond-like carbon (DLC) protective film is used from the viewpoints of chemical stability, strength, ultrathinness, smoothness and the like. As is apparent from the structure, the protective film is mostly composed of carbon, and therefore has a low chemical bonding property and a small adhesive force such as hydrogen bonding with hydrogen and nitrogen atoms and van der Waals force. There is nothing else due to the interaction.

Therefore, as a lubricant, a perfluoroalkyl polyether oligomer (hereinafter abbreviated as “PFPE”) is generally used (Monthly Tribology, No. 99,
November, pp. 37-38, 1995). PFPE has low surface energy, chemical inertness, low vapor pressure, and thermal stability derived from fluorocarbon, but because of its low surface energy, the bonding force with the protective film surface is weak, and the lubricant is generated by the centrifugal force of disk rotation. However, there is a drawback that they move and disappear from the protective film. In order to suppress this, an additive of the second component is used (US Pat. No. 4,871,625), but due to the low compatibility derived from fluorocarbon of PFPE, phase separation is caused and sufficient effect is not obtained at present. is there.
Therefore, in order to impart a binding property to PFPE, a functional group such as a hydroxyl group or an acylamide group is introduced into the end or the center of the PFPE main chain (Aushimont, FOMBLIN, Inc.).
Z derivative), but these functional groups having active hydrogen may reduce chemical stability due to friction with the head.

Further, a perfluoroalkoxy phosphazene compound is disclosed as a treating agent for a magnetic recording medium (Japanese Patent Application Laid-Open No. 63-103428). Since the CSS durability cannot be obtained, a new lubricant is desired.

An object of the present invention is to provide, for example, a hard disk lubricant having good CSS durability.

[0010]

The present invention provides -CF ₂ O-,
The following formulas (1) and (5) comprising a sequence in which perfluorooxyalkylene units selected from —CF ₂ CF ₂ O— are randomly distributed and further having a functional terminal group A.
The present invention relates to a lubricant containing a phosphazene compound represented by the formula: A-OCH ₂ CF ₂ O (CF ₂ CF ₂ O) p (CF ₂ O) qCF ₂ CH ₂ O-A (1) A- [OCH ₂ CF ₂ O (CF ₂ CF ₂ O) p (CF ₂ O ) qCF ₂ CH ₂ OH] _{6 -z} (5) wherein A is a group represented by the following formula (a). Here, R represents a hydrogen _{atom, C 1 to 4 alkyl,} a _{C 1 to 4 alkoxy,} a _{C 1 to 4} haloalkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, p and q are 1 A real number of 30 and z is an integer of 1 to 5. ]

[0011]

Embedded image

[0012]

DETAILED DESCRIPTION OF THE INVENTION Here, the alkyl C _{1 to 4} for example, can be exemplified by methyl, ethyl, propyl, butyl and the like. Examples of C _1-4 alkoxy include methoxy, ethoxy, propoxy, butoxy and the like. The haloalkyl of C _{1 to 4} for example, fluoromethyl, trifluoromethyl, chloromethyl, fluoroethyl, trifluoroethyl, bromoethyl, iodopropyl, fluoro butyl, chlorobutyl, can be exemplified bromobutyl like. Examples of aryl include phenyl,
Examples include naphthyl. Examples of aryloxy include phenoxy, naphthoxy and the like. Examples of the substituent of the substituted aryl and the substituted aryloxy include the above-mentioned C _1-4 alkyl, C _1-4 alkoxy, C _1-4
And the like.

In the present invention, the phosphazene compound of the above formula (1) is a novel compound not described in the literature. For example, a phosphonitrile halide oligomer and a phenol or an alcohol having hydroxyl groups introduced at both ends of the PFPE main chain can be used. It is a manufactured substance. Here, examples of the oligomer of phosphonitrile halide include a cyclic trimer of phosphonitrile chloride, a cyclic tetramer of phosphonitrile chloride, and a mixture thereof. Examples of phenols include haloalkoxyphenols such as phenol and meta-trifluoromethylphenol, and alkoxyphenols such as meta-methoxyphenol. Further, as the alcohol having hydroxyl groups introduced at both ends of the PFPE main chain, a perfluoroalkyl polyether oligomer having an average molecular weight of the following formula (b) of 400 to 6000 (Zu derivative of Asimont Corporation)
Can be exemplified. HOCH ₂ CF ₂ O (CF ₂ CF ₂ O) r (CF ₂ O) sCF ₂ CH ₂ OH (b) [r = 1 to 30, s = 1 to 30]

The compound (1) of the present invention is produced, for example, as follows. That is, as described in JP-A-62-53996, alcohols and phenols are previously reacted with sodium or the like to form alcoholates and phenolates, and then reacted with a cyclic oligomer of phosphonitrile halide. . More specifically, phenols are dissolved in a solvent such as diethyl ether, diisopropyl ether, toluene or the like, and less than the equivalent required to convert all the phenols to phenolate, preferably 85 to 95% equivalent of metal sodium, hydrogen By reacting a base such as sodium chloride at the reflux temperature of the solvent until all of these bases have reacted,
Obtain the phenolate. 15-2 of the obtained phenolate
Reaction with 5% equivalents, preferably 18-21% equivalents, of the cyclotrimer of the phosphonitrile halide gives the aryloxy-substituted tricyclophosphonitrile halide. Separately,
An alcohol having a hydroxyl group introduced into both ends of PFPE (hereinafter abbreviated as “PFPE-DOH”) and a base selected from the above bases are added in the same equivalent amount, and solidified at room temperature to 120 ° C., preferably 40 to 100 ° C. The reaction is continued until the base is no longer visible.

The aryloxy-substituted tricyclophosphonitrile halide obtained above and the alcoholated PFP
E-DOH is reacted in an ether solvent such as diethyl ether, diisopropyl ether, perfluorohexyl methyl ether or the like for 1 to 10 days, preferably 2 to 5 days, from room temperature to the reflux temperature of the solvent.
The reaction mixture obtained in this reaction is added to an ether solvent solution containing a phenolate separately prepared by the above method, and the mixture is heated from room temperature to the reflux temperature of the solvent, preferably at the reflux temperature.
The reaction is allowed to complete for 5 to 15 days until no partially halogenated tricyclophosphonitrile is detected. After washing the reaction mixture several times with water,
After dehydration and drying, the solvent used is removed by distillation under reduced pressure. When the unreacted phenols, PFPE-DOH and hexaaryloxy-substituted tricyclophosphonitrile are present from the obtained reaction mixture, these compounds are distilled off by molecular distillation to remove the above compound ( 1) is manufactured.

In the present invention, in addition to the compound of the formula (1), compounds having a high molecular weight such as the following formulas (2) and (3) may be present in the reaction system. A small amount of such a compound may be present in the lubricant of the present invention. Here, B is a group represented by the formula (4).

[0017]

Embedded image

—CH ₂ CF ₂ O (CF ₂ CF ₂ O) r (CF ₂ O) sCF ₂ CH ₂ — (4) [r = 1 to 30, s = 1 to 30]

The synthesis of the compound of formula (1) is carried out as described above.
Because it takes time, complete the reaction when considering economics.
Instead, it may be stopped at an appropriate place. In this case,
A compound such as formula (5) may optionally contain, for example, 5%
Although such a compound may occur as described above, such a compound (1)
The object of the present invention is inhibited even if coexisting with
And not. The ratio of compound (1) to compound (5) is within a wide range.
Box, for example, former / latter (weight ratio) = 5-9
5 / 95-5, preferably 20-80 / 80-20.
An example can be given. A- [OCH₂CF₂O (CF₂CF₂O) p (CF₂O) qCF₂CH₂OH] _6-z (5) wherein A, p, q and z are the same as above.

The compounds of the present invention are suitable for uses such as nonflammable lubricating oils and hydraulic oils, and particularly for recording medium lubricants.
When the phosphazene compound of the present invention is used for a lubricant, the phosphazene compound may be used as a lubricant as it is, or may be used after being dissolved in an appropriate organic solvent. Examples of the organic solvent include toluene, aromatic hydrocarbons such as xylene, methylene chloride, chloroform,
1,1,1-trichloroethane, 1,1,2-trichloroethane, trichlorotrifluoroethane (CFC 11
3), perfluorohexyl methyl ether (HFE-
Halogenated hydrocarbons such as 7100), ethers such as diethyl ether, dimethoxyethane, dioxane and tetrahydrofuran; esters such as ethyl acetate, butyl butyrate and amyl acetate; alicyclic hydrocarbons such as cyclohexane, cycloheptane and cyclooctane; Examples thereof include formamide, dimethyl sulfoxide, and a mixed solvent of two or more of these.

When the lubricant of the present invention is used as a lubricant for a recording medium, the total concentration of the compounds of the formulas (1) and (5) may be at least 0.1% by weight, usually 0.1 to 100% by weight. ,
Preferably 10 to 100% by weight, more preferably about 20%
About 100% by weight. In the present invention, the compounds of the formulas (1) and (5) and the formula (b) have an average molecular weight of 40.
0 to 6000 perfluoroalkyl polyether oligomers may be used in combination. HOCH ₂ CF ₂ O (CF ₂ CF ₂ O) r (CF ₂ O) sCF ₂ CH ₂ OH (b) [r = 1 to 30, s = 1 to 30]

In the present invention, the compounds of formulas (1) and (5) can be used in combination with the following perfluoroalkyl polyether oligomer (c). _{X-CF 2 O (CF 2} CF 2 O) m (CF 2 O) nCF 2 -Y (c) [X, Y is _{HO (CH 2 CH 2 O)} tCH 2 -, HO
It represents at least one group selected from CH ₂ CH (OH) CH ₂ OCH ₂ —, HOOC— and a piperonyl group.
m = 1-80, n = 1-80, t = 1-30] Examples of the oligomer (c) include FOMBLIN
ZDol-TX, Z-TETRAOL, Z-DIAC,
AM3001 (both manufactured by Ausimont) and the like.

In the present invention, the compounds of formulas (1) and (5) can be used in combination with the following perfluoroalkyl polyether oligomer (d). F [CF (CF ₃ ) CF ₂ O] uCF (CF ₃ ) COOH (d) [u = 1-60] As an example of the oligomer (d), KRYTOX 1
57FS (DuPont) and the like.

In the present invention, the compounds of the formulas (1) and (5) can be used in combination with the following phosphazene compound (e). [N = P {OCH ₂ CF ₂ CF ₃ } a {OCH ₂ (CF ₂ CF ₂ ) xH} b] y (e) wherein a and b are real numbers from 0 to 2 and a + b = 2 , X is 1, 2, 3 or 4, and y is 3 or 4. Examples of the phosphazene compound (e) include Moresco phosphalol NF-100, NF-46 (Matsumura Petroleum Institute Co., Ltd.) and the like.

When the compounds (b), (c), (d) and (e) are used in combination, the concentration of each compound is preferably at least 0.1% by weight, usually about 10 to 90% by weight. Further, at least two kinds of the compounds (b), (c), (d) and (e) can be used in combination.

[0026]

The present invention will be described in more detail with reference to the following examples, but it should not be construed that the invention is limited thereto. The reactions described below were all performed in an argon gas atmosphere.

EXAMPLE 1 282.1 g (1.74 mol) of meta-trifluoromethylphenol was placed in a two-liter four-necked flask equipped with a reflux condenser, an argon gas inlet, a thermometer and a stirrer, and dried, dehydrated and distilled. 1.2 L of purified diisopropyl ether
While stirring, remove small pieces of metallic sodium into 36.
5 g (1.59 mol) was added and reacted at a temperature at which diisopropyl ether was refluxed for 2 days. After confirming that all the sodium metal had been consumed, cyclotrimer of phosphonitrile chloride was added while stirring the reaction mixture. 107.7 g (0.31 mol) was added and reacted at reflux temperature for 3 days to obtain about 1300 g of reaction mixture. After the reaction mixture was washed 5 times with about 500 ml of purified water, the diisopropyl ether layer was separated, dehydrated with molecular sieves, and the diisopropyl ether was removed under reduced pressure.
Distillation and removal were performed using a rotary evaporator to obtain a brown transparent liquid. Assume this.

In the same flask as above, PFPE-DO
H ｛A diol having an average molecular weight of 2000, in which the average values of r and s in the above formula (b) are 10.8 and 9.7, respectively｝ 302 g (0.151 mol) and small pieces of metallic sodium 3 0.5 g (0.151 mol)
After reacting at 0 ° C. for 12 days, it was confirmed that all the metallic sodium was consumed in the reaction, and 450 g of perfluorohexyl methyl ether was added to lower the viscosity of the reaction product. A solution obtained by dissolving 150.5 g of the compound in 140 g of diisopropyl ether was gradually added dropwise thereto, and the mixture was stirred at a reflux temperature for 3 days and then cooled to room temperature. Let the obtained reaction mixture be.

In the same manner as in the above preparation, meta-trifluoromethylphenol (192.7 g, 1.19 mol)
In a solution containing 1.19 mol of meta-trifluoromethylphenolate and 700 g of diisopropyl ether separately prepared from 24.8 g (1.08 mol) of small pieces of sodium and metallic sodium, the entire amount of the above reaction mixture was mixed with perfluorohexylmethyl. The mixture was quantitatively added using 230 g of ether, and reacted by stirring at the reflux temperature of the solvent for 9 days. In this reaction mixture, it was confirmed by capillary gas chromatography that the cyclotrimer of phosphonitrile in which only the meta-trifluoromethylphenoxy group and the chlorine atom were both substituted in a mixed state, that is, no reaction intermediate was present. Thereafter, the contained solvent was distilled off from the reaction mixture under reduced pressure by a rotary evaporator, and the obtained residue was dissolved in 200 g of diethyl ether. This diethyl ether solution was washed three times with 200 g of a 1% aqueous nitric acid solution, and further washed four times with 200 g of purified water. After these operations, the diethyl ether layer was dehydrated and dried with molecular sieves, and the diethyl ether was evaporated under reduced pressure by a rotary evaporator to obtain 350 g of a slightly turbid oily liquid.

After removing the cyclotrimer (by-product) of phosphonitrile substituted with 6 meta-trifluoromethylphenoxy groups from the reaction mixture by washing with toluene, 270 g of a transparent yellow liquid was obtained. This liquid was extracted with supercritical carbonic acid to give 60 g of compound (1-a) (0.015 g).
Mol) and 80 g (0.027 mol) of compound (5-a).

(CF₃C₆H₄O)₅P₃N₃OCH₂CF₂(OCF₂CF₂)_11.6(OCF ₂ )_10.6OCF₂CH₂ON₃P₃(OC₆H₄CF₃)₅ [Compound (1-a)] (CF₃C₆H₄O)₅P₃N₃OCH₂CF₂(OCF₂CF₂)_11.6(OCF ₂ )_10.6OCF₂CH₂OH [compound (5-a)]

400 MHz proton NMR and F-NM
According to R, the obtained substance is compound (1-a)
PE-DOH is a compound having a phosphonitrile cyclotrimer in which five meta-trifluoromethylphenoxy groups are substituted at both terminals, and compound (5-a) is PF
It was a compound having a phosphonitrile cyclotrimer substituted with five meta-trifluoromethylphenoxy groups at one end of PE-DOH.

Example 2 Meta-phenoxyphenol was used in place of meta-trifluoromethylphenol described in Example 1, and meta-phenoxy was added to both ends of PFPE-DOH by the same reaction as in Example 1. Compound (1-b) having cyclotrimer of phosphonitrile substituted with five phenoxy groups
35 g and 65 g of a compound (5-b) having a phosphonitrile cyclotrimer in which five meta-phenoxyphenoxy groups were substituted at one end of PFPE-DOH were obtained.

EXAMPLE 3 18.3 g (0.11 mol) of meta-trifluoromethylphenol was dried and dehydrated in a 0.5-liter four-necked flask equipped with a reflux condenser, an argon gas inlet, a thermometer and a stirrer. And diisopropyl ether 0.1
Then, 2.3 g (0.1 mol) of a small piece of metallic sodium was added with stirring, and reacted at reflux temperature for 2 days. After confirming that all metallic sodium was consumed, the reaction mixture was added. While stirring, 10.8 g (0.03 mol) of cyclotrimer of phosphonitrile chloride was added and reacted at reflux temperature for 3 days to obtain about 25 g of a reaction mixture. After washing the reaction mixture 5 times with about 50 ml of purified water, the diisopropyl ether layer was separated, dehydrated with molecular sieves, and the diisopropyl ether was distilled off under reduced pressure using a rotary evaporator to obtain a brown transparent liquid. Assume this.

In the same flask as above, 20 g (0.01 mol) of the PFPE-DOH used in Example 1 and 0.23 g (0.01 mol) of a small piece of metallic sodium were placed, and the mixture was heated at 50 ° C. to 100 ° C. for 12 days. After the reaction, it was confirmed that all the metallic sodium had been consumed in the reaction, and 45 g of perfluorohexyl methyl ether was added to lower the viscosity of the reaction product. A solution prepared by dissolving 2.2 g of this compound in 14 g of diisopropyl ether was gradually added dropwise thereto, and the mixture was stirred at a reflux temperature for 3 days and then cooled to room temperature. The obtained reaction mixture was washed with a 1% aqueous nitric acid solution, purified water, and toluene to obtain 18 g of a compound.

400 MHz proton NMR and F-NM
The material obtained by R and FT-IR was PFPE
A compound having a phosphonitrile cyclotrimer in which an average of three meta-trifluoromethylphenoxy groups were substituted at only one terminal of -DOH. This compound is referred to as compound (5-c).

Comparative Example 1 (Compound described in JP-A-6-220077) C ₃ F ₇ O (C) was placed in a 1-liter four-necked flask equipped with a reflux condenser, an argon gas inlet pipe, a thermometer and a stirrer.
_{F 2 CF 2 O) 2 CF} 2 CH 2 OH 41.3g (0.08
3 liters), 0.5 liters of diisopropyl ether dried and dehydrated and purified by distillation, and while stirring, 1.73 g (0.075 mol) of small pieces of metallic sodium were added.
After reacting all the metal sodium at 6.degree. C., 6.95 g (0.02 mol) of cyclotrimer of phosphonitrile chloride and diisopropyl ether
40 ml was added and reacted at 60-70 ° C. for 2 days.
Let the obtained reaction mixture be.

In the same manner as described above, phenol 18.
8 g (0.198 mol) and 4.14 g of metallic sodium
(0.18 mol) in 250 ml of diisopropyl ether
For 5 days to obtain a solution of sodium phenolate in diisopropyl ether. This solution is used.

In a flask containing the entire amount of the solution,
After charging at room temperature for about 5 minutes and reacting at 70 ° C. for 10 days, the diisopropyl ether solution of the reaction mixture was washed with an aqueous sodium hydroxide solution, then washed four times with an aqueous nitric acid solution, and further washed six times with purified water. Washed. The diisopropyl ether solution obtained by these washings was dehydrated and dried with molecular sieves, and the diisopropyl ether was distilled off under reduced pressure by a rotary evaporator to obtain 23.3 g of a pale yellow liquid [compound (D)]. Table 1 shows the physical properties of the compounds.
Shown in

[0040]

[Table 1]

Test Example 1 Using the compounds obtained in Examples 1 to 3 and Comparative Example 1, a performance test of a lubricant was performed. 1 g of the test compound was added to perfluorohexyl methyl ether (HFE-7100) 100
After the hard disk was immersed in a solution dissolved in 0 ml, it was taken out and dried at 120 ° C. for 30 minutes to form a film having a thickness of 10 ° on the hard disk. This was subjected to the following test. The performance test of the lubricant was carried out by measuring the change in the coefficient of friction by a CSS repetition test using an actual drive modified so that the coefficient of friction could be measured from the force applied to the head. The CSS cycle starts with the head in contact with the disk surface, and after reaching a predetermined number of times 7200 rpm with the head floating, performs a process until the head stops again with the head in contact with the disk surface in 33 seconds. This was one cycle. The hard disk is DLC of 100-200Å on a recording medium prepared by 3.5 inch sputtering by plasma CVD.
A protective film was prepared, and no texture was applied to enhance the surface smoothness. Head is monolithic MIG
The load was 7.5 g in (metal in gap). The quality of the CSS test was determined based on the number of cycles (CSS life) until the head and the disk adhere (crash), the state of the disk (whether or not worn) and the degree of contamination of the head after the test. The test results are shown in Tables 2 to 4. In the head dirt shown in the table,-; no dirt ±; slightly present +; slightly present ++; solid matter attached.

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

From the table, the compounds (1-a), (5-a),
Even if (1-b), (5-b), and (5-c) are used alone, they show sufficiently excellent performance for the purpose of the present purpose. It has been found that not only the life but also the dirt on the head is reduced. For example, with the compound (1-a) alone, head staining was observed after the test, but the compound (1-a) and the compound (5-a) and (5-b)
In the case where was added, head contamination could be reduced.

This is believed to be related to the relative amount of hydroxyl groups in the mixture. Compound (5-a) has more hydroxyl groups in the molecule than compound (1-a),
It is presumed that the bonding force with the DLC protective film was high, and as a result, the transfer of the lubricant to the head was reduced. A compound having relatively few hydroxyl groups has an adsorptivity to the DLC protective film,
It is considered that the film is relatively weak, so that it is easily detached from the DLC protective film and easily transferred to the head. But CSS
It is also clear that a compound having a relatively small number of hydroxyl groups {for example, compound (1-a)} has a longer life. In order to maintain relative performance, it is necessary to maintain the relative performance of the compound constituting the lubricant. It became clear that the quantitative balance of hydroxyl groups was important. The compound (D) having no hydroxyl group originally has C
The SS life was a result unsuitable for practical use. As described above, it has been clarified that the use of the mixture according to the present invention as a lubricant can improve the CSS durability of a magnetic recording medium.

[0047]

According to the present invention, for example, a hard disk lubricant having good CSS durability can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C10N 20:04 C10N 20:04 30:06 30:06 40:18 40:18 (72) Inventor Eiyoshi Kobayashi 10-33, Ashihara-cho, Nishinomiya-shi, Hyogo Pref. In Matsumura Oil Research Laboratory Co., Ltd. (72) Inventor Rie 10-33, Ashihara-cho, Nishinomiya-shi, Hyogo Pref. EA03A LA03 PA16 5D006 AA01

Claims (6)

[Claims] 1. A _{-CF 2 O -, - CF 2} CF 2 O-,
A lubricant containing a phosphazene compound represented by the following formulas (1) and (5), which has a sequence in which perfluorooxyalkylene units selected from the above are randomly distributed and further has a functional terminal group A. A-OCH ₂ CF ₂ O (CF ₂ CF ₂ O) p (CF ₂ O) qCF ₂ CH ₂ O-A (1) A- [OCH ₂ CF ₂ O (CF ₂ CF ₂ O) p (CF ₂ O ) qCF ₂ CH ₂ OH] _{6 -z} (5) wherein A is a group represented by the following formula (a). Here, R represents a hydrogen _{atom, C 1 to 4 alkyl,} a _{C 1 to 4 alkoxy,} a _{C 1 to 4} haloalkyl, aryl, substituted aryl, aryloxy, substituted aryloxy, p and q are 1 A real number of 30 and z is an integer of 1 to 5. ] 2. The lubricant according to claim 1, further comprising a perfluoroalkyl polyether oligomer of the formula (b) having an average molecular weight of 400 to 6000. HOCH ₂ CF ₂ O (CF ₂ CF ₂ O) r (CF ₂ O) sCF ₂ CH ₂ OH (b) [r = 1 to 30, s = 1 to 30] 3. The lubricant according to claim 1, further comprising a perfluoroalkyl polyether oligomer of the formula (c). _{X-CF 2 O (CF 2} CF 2 O) m (CF 2 O) nCF 2 -Y (c) [X, Y is _{HO (CH 2 CH 2 O)} tCH 2 -, HO
_{CH 2 CH (OH) CH 2} OCH 2 -, represents at least one group selected from HOOC- or piperonyl group.
m = 1-80, n = 1-80, t = 1-30] 4. The lubricant according to claim 1, further comprising a perfluoroalkyl polyether oligomer of the formula (d). _{F [CF (CF 3) CF} 2 O] uCF (CF 3) COOH (d) [u = 1~60] 5. The lubricant according to claim 1, further comprising a phosphazene compound of the formula (e). [N = P {OCH ₂ CF ₂ CF ₃ } a {OCH ₂ (CF ₂ CF ₂ ) xH} b] y (e) wherein a and b are real numbers from 0 to 2 and a + b = 2 , X is 1, 2, 3 or 4, and y is 3 or 4. ] 6. The lubricant according to claim 1, wherein the lubricant is a lubricant for a recording medium.