JP2009270093A - Perfluoropolyether compound, lubricant containing the same, and magnetic disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound having reduced film thickness per one molecule and fluidity compatibly, to provide a lubricant using the compound, and to provide a magnetic disk. <P>SOLUTION: The compound is represented by formula (1), the lubricant uses the compound, and the magnetic disk uses the lubricant, formula (1): [HO-(CH<SB>2</SB>-R<SP>2</SP>-CH<SB>2</SB>O-A-O)<SB>n</SB>-CH<SB>2</SB>-R<SP>2</SP>-CH<SB>2</SB>-O-CH<SB>2</SB>]<SB>p</SB>-R<SP>1</SP>. In formula, n is an integer of 0-6, and A is a group represented by -CH<SB>2</SB>CH(OH)CH<SB>2</SB>-. R<SP>1</SP>is an aromatic group of C<SB>6</SB>H<SB>6-p</SB>, C<SB>6</SB>H<SB>5-q</SB>-O-C<SB>6</SB>H<SB>5-r</SB>, and C<SB>10</SB>H<SB>8-p</SB>. p is an integer of 3-6, q and r are respectively integers of 0 or more, and p=q+r. R<SP>2</SP>is -CF<SB>2</SB>O(CF<SB>2</SB>CF<SB>2</SB>O)<SB>x</SB>(CF<SB>2</SB>O)<SB>y</SB>CF<SB>2</SB>- or -CF<SB>2</SB>CF<SB>2</SB>O(CF<SB>2</SB>CF<SB>2</SB>CF<SB>2</SB>O)<SB>z</SB>CF<SB>2</SB>CF<SB>2</SB>-. x and y are respectively real numbers of 0-30, and z is a real number of 1-30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a perfluoropolyether compound having an aromatic group and a hydroxyl group, a lubricant containing the same, and a magnetic disk using the same.

  As the recording density of the magnetic disk increases, the distance between the magnetic disk, which is a recording medium, and the head for recording / reproducing information is reduced until it almost comes into contact. A carbon protective film and a lubricant film are provided on the surface of the magnetic disk for the purpose of suppressing wear during contact / sliding with the head and preventing contamination of the disk surface.

  The carbon protective film is generally formed by sputtering or CVD. Since the surface protection of the disk is carried out by both the carbon protective film and the lubricant film located in the upper layer, the interaction between the carbon protective film and the lubricant is important.

  As the lubricant, a perfluoropolyether having a functional group is generally used. Examples of the functional group include a hydroxyl group, an amino group, and a cyclophosphazene group. Specifically, Fomblin ZTETRAOL manufactured by Solvay Solexis as a lubricant having a hydroxyl group at the molecular end, PHOSFAROL A20H manufactured by Matsumura Oil Research Institute, which has a hydroxyl group at one end of the molecule and a cyclophosphazene group at the other end, etc. is there. Further, a lubricant having a hydroxyl group in the molecular chain in addition to the molecular end has been proposed (see Patent Document 1).

Fomblin ZTETRAOL exhibits good adsorptivity to the disk due to the hydroxyl groups located at both ends of the molecule, and does not scatter even when the disk rotates at high speed and can maintain the lubricant coating. In addition, PHOSFAROL A20H has a hydroxyl group that contributes to adsorption to the disk at one end of the molecule and a cyclophosphazene group that suppresses cleavage of the perfluoropolyether main chain by Lewis acid at the other end. The decomposition of the compound by Al ₂ O ₃ in the member is also suppressed, and the lubricant film can be maintained on the disk (see, for example, Patent Document 2).

  Further, Patent Document 1 describes the influence of the lubricant film thickness on the head and disk spacing. In order to reduce the spacing, it is effective to reduce the film thickness of one molecule of the lubricant, and the lubricant having a hydroxyl group in the molecular chain in addition to the molecular end increases the film thickness of one molecule of the lubricant. It has been proposed that it can be reduced. With this technique, the film thickness of one molecule of the lubricant can be kept low, and the lubricant can have a high molecular weight, and the lubricant can be prevented from evaporating.

  However, since the hydroxyl group of the lubricant forms hydrogen bonds with hydroxyl groups on the carbon protective film and covalent bonds with dangling bonds (unbonded hands) (for example, Non-Patent Document 1), The lubricant film made of a compound having a hydroxyl group is a film fixed to the carbon protective film. Fixing the lubricant film leads to a decrease in fluidity, which is a contradictory characteristic, and therefore there is a possibility that the sliding durability is greatly insufficient under low spacing conditions where the contact probability between the head and the disk is high.

JP 2006-70173 A US Pat. No. 6,608,090

IEEE Transactions on Magnetics, vol. 37, No. 2, March 2001

  An object of the present invention is to provide a compound that can contribute to a reduction in the spacing between the head and the disk, and that exhibits good fluidity on the disk surface, thereby exhibiting sliding durability.

The present invention relates to the following inventions.
1. The compound represented by Formula (1).
[HO— (CH ₂ —R ² —CH ₂ O—AO) _n —CH ₂ —R ² —CH ₂ —O—CH ₂ ] _p —R ¹ (1)
In the formula, n is an integer of 0 to 6, and A is a group represented by —CH ₂ CH (OH) CH ₂ —. R ¹ is _{C 6 H 6-p, C} 6 H 5-q -O-C 6 H 5-r, aromatic group _C 10 _{H 8-p.} p is an integer of 3-6. q and r are each an integer of 0 or more, and p = q + r. R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ — or —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —. x and y are real numbers of 0 to 30, respectively. z is a real number of 1-30.

2. A lubricant containing a compound of formula (1).
3. A magnetic disk having at least a recording layer and a protective layer formed on a support and having a lubricating layer on the surface thereof, wherein the lubricating layer contains a compound represented by the formula (1).

  The perfluoropolyether compound having an aromatic group and a hydroxyl group of the present invention is a lubricant that simultaneously solves two problems of film thickness reduction and fluidity per molecule. In addition, a magnetic disk using the compound of the present invention as a lubricant can reduce the spacing between the head and the disk, and has excellent durability even in sliding contact between the head and the disk.

It is a cross-sectional schematic diagram which shows the structure of the magnetic disk of this invention.

  The perfluoropolyether represented by the formula (1) of the present invention is a perfluoropolyether compound having an aromatic group and a hydroxyl group.

  The perfluoropolyether compound having an aromatic group and a hydroxyl group of the present invention represented by the formula (1) is synthesized, for example, by the following method.

Under an argon atmosphere, a perfluoropolyether having hydroxyl groups at both ends represented by HOCH ₂ —R ² —CH ₂ OH is heated and stirred together with t-butanol and t-butoxypotassium. The reaction temperature is 60 to 80 ° C, preferably 65 to 70 ° C. An epihalohydrin compound, for example, epibromohydrin is dropped here, and the heating and stirring are continued for 3 to 8 hours, preferably 4 to 6 hours. Thereafter, fractionation is performed by, for example, washing with water and column chromatography to obtain an intermediate compound. This is heated and stirred together with metallic sodium under an argon atmosphere. The reaction temperature is 50 to 100 ° C, preferably 60 to 80 ° C. The reaction time is 10 to 70 hours, preferably 20 to 50 hours. It is preferable to use 0.7 to 1 equivalent of metallic sodium based on perfluoropolyether. Subsequently, an aromatic compound having p halogen atoms represented by X ¹ _p -Y is added thereto. The reaction temperature is 50 to 100 ° C, preferably 60 to 80 ° C. The reaction time is 20 to 50 hours, preferably 30 to 40 hours. It is preferable to use 0.2 to 0.8 equivalent of an aromatic compound having p halogen atoms relative to perfluoropolyether. The reaction may be performed in a solvent. Thereafter, fractionation is performed by, for example, washing with water and column chromatography, and the target compound is obtained as a fraction.

As a perfluoropolyether having a hydroxyl group at both ends represented by HOCH ₂ —R ² —CH ₂ OH, for example, HOCH ₂ —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ and _{-CH 2 OH, HOCH 2 -CF 2} CF 2 O (CF 2 CF 2 CF 2 O) z CF 2 C
An example is F ₂ —CH ₂ OH. Here, x and y are each a real number of 0 to 30, preferably 0 to 25, more preferably 0 to 20, and still more preferably 0 to 15. z is a real number of 1 to 30, preferably 1 to 25, more preferably 1 to 20, and still more preferably 1 to 15. Both are compounds having a molecular weight distribution.

In the aromatic compound having a halogen atom represented by X ¹ _p -Y, X ¹ can be exemplified by chlorine, bromine and iodine, and further CH ₂ Cl, CH ₂ Br and CH ₂ I. Adding position of the X ¹ is ortho, meta, either para good. Here, p is a real number of 3-6. Y is, for example _{-C 6 H 6-p, -C} 6 H 5-q -O-C 6 H 5-r - ( where _{p = q + r), -} C 10 H 8-p to be exemplified.

  When the perfluoropolyether compound having an aromatic group and a hydroxyl group of the present invention represented by the formula (1) is used as a lubricant, n = 0 to 6 is preferable, and n = 0 to 3 is more preferable. Yes, more preferably n = 0-2.

  In order to apply the compound of the present invention to the surface of the magnetic disk, a method in which the compound is diluted with a solvent and applied is preferred. Examples of the solvent include 3M PF-5060, PF-5080, HFE-7100, HFE-7200, and DuPont Vertrel-XF. The concentration of the diluted compound is 1 wt% or less, preferably 0.001 to 0.1 wt%.

  In addition to using the compound of the present invention alone, for example, PHOSFAROLA 20H manufactured by Matsumura Oil Research Institute, Fomblin Zdol or Ztetraol, Zdol TX, AM manufactured by Solvay Solexis, Demnum manufactured by Daikin Industries, Krytox manufactured by Dupont, etc. It can also be used by mixing at a ratio.

The compound of the present invention can be used as a lubricant for realizing low spacing between the magnetic disk and the head in the magnetic disk apparatus and further improving the sliding durability. In addition, the compound of the present invention interacts with polar sites present in the carbon protective film due to hydroxyl groups at the molecular ends, and also with carbon unsaturated bonds present in the carbon protective film due to aromatic groups in the molecular chain. It is characterized by forming an action. Therefore, in addition to the magnetic disk, a magnetic head having a carbon protective film, a magneto-optical recording device, a magnetic tape, etc., a surface protective film of an organic material such as carbon fiber, carbon nanotube, and plastic, and further Si ₃ N ₄ , SiC It can also be applied as a surface protective film of inorganic materials such as SiO ₂ .

The magnetic disk of the present invention has at least one recording layer 2 on a support 1, a protective layer 3 thereon, and a lubricating layer 4 containing the compound of the present invention as an outermost layer. is there. FIG. 1 shows a schematic diagram of a cross section of a magnetic disk of the present invention.
Examples of the support include aluminum alloys, ceramics such as glass, polycarbonate, and the like.

The constituent material of the magnetic layer that is the recording layer of the magnetic disk is mainly an element capable of forming a ferromagnetic material such as iron, cobalt, nickel, etc., and an alloy obtained by adding chromium, platinum, tantalum, etc. to this, or oxidation thereof. Things. These are formed by plating or sputtering.
Examples of the material for the protective layer include carbon, SiC, and SiO ₂ . These are formed by sputtering or CVD.

  Since the thickness of the currently distributed lubricating layer is 30 mm or less, if a lubricant having a viscosity of about 100 mPa · s or more at 20 ° C. is applied as it is, the film thickness may be too large. Therefore, a solution dissolved in a solvent is used for coating. Whether the compound of the present invention is used alone as a lubricant or mixed with other lubricants, it is easier to control the required film thickness when dissolved in a solvent. However, the concentration varies depending on the application method, conditions, mixing ratio, and the like. The film thickness of the lubricant of the present invention is preferably 5 to 15 mm.

  In order to promote the adsorption of the lubricant to the underlayer, heat treatment or ultraviolet treatment can be performed. The heat treatment temperature is 60 to 150 ° C, preferably 80 to 150 ° C. In the ultraviolet treatment, it is preferable to use ultraviolet rays having wavelengths of 185 nm and 254 nm as main wavelengths.

The magnetic disk of the present invention is a magnetic disk drive equipped with a head for storing the disk and recording / reproducing / erasing information, a motor for rotating the disk, etc., and a control for controlling the drive. The present invention can be applied to magnetic disk devices composed of a system. Examples of the recording method of the magnetic disk device include in-plane magnetic recording, perpendicular magnetic recording, and heat-assisted magnetic recording. It can also be applied to a discrete track type magnetic disk and a bit patterned type magnetic disk.
Applications of the magnetic disk of the present invention and the magnetic disk device to which the magnetic disk is applied include an external memory such as an electronic computer and a word processor. It can also be applied to various devices such as navigation systems, games, mobile phones, PHS, and crime prevention of buildings, internal / external recording devices of management / control systems such as power plants.

Hereinafter, the present invention will be specifically described with reference examples, examples, and test examples, but the present invention is not limited to these examples. ¹⁹ F-NMR is a solvent; none, reference substance: OCF ₂ C F ₂ CF ₂ O contained as a main component or a trace impurity is set to −129.7 ppm, ¹ H-NMR is a solvent: none, reference substance: D _The measurement was performed under the condition of 2O.

Reference example 1
Synthesis of HO— (CH ₂ —R ² —CH ₂ O—CH ₂ CH (OH) CH ₂ —O) _n —CH ₂ —R ² —CH ₂ —OH (Intermediates 1, 2, 3) where R ² is —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —. Intermediate 1 has n = 1, Intermediate 2 has n = 2, and Intermediate 3 has n = 3.
Under an argon _{atmosphere, HOCH 2 -CF 2 CF 2 O} (CF 2 CF 2 CF 2 O) a perfluoropolyether represented by _z CF 2 CF 2 _-CH 2 OH and (42 g), t-butanol (18 g) and Stir at 70 ° C. with potassium t-butoxy (5.4 g). Epibromohydrin (3.3 g) is added dropwise and stirring is continued for 4-6 hours. Thereafter, it was washed with water and subjected to supercritical extraction to give 5 fractions. Intermediate 1 (15 g) as the second fraction, Intermediate 2 (26 g) as the third fraction, and Intermediate 3 (17 g) as the fourth fraction. )

Reference example 2
Synthesis of HO— (CH ₂ —R ² —CH ₂ O—CH ₂ CH (OH) CH ₂ —O) _n —CH ₂ —R ² —CH ₂ —OH (Intermediates 4, 5, 6) R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ —. Intermediate 4 has n = 1, Intermediate 5 has n = 2, and Intermediate 6 has n = 3.
Under an argon atmosphere, perfluoropolyether (42 g) represented by HOCH ₂ —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ —CH ₂ OH, t-butanol (18 g) and Stir at 70 ° C. with potassium t-butoxy (5.4 g). Epibromohydrin (3.3 g) is added dropwise and stirring is continued for 4-6 hours. Thereafter, it was washed with water and subjected to supercritical extraction to give 5 fractions, intermediate 4 (17 g) as the second fraction, intermediate 5 (24 g) as the third fraction, and intermediate 6 (13 g) as the fourth fraction. )

Example 1
Synthesis of [HO—CH ₂ —R ² —CH ₂ O—CH ₂ CH (OH) CH ₂ —O—CH ₂ —R ² —CH ₂ —O—CH ₂ ] ₃ —R ¹ (Compound 1) , R ¹ is a group represented by the following formula (a), and R ² is —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —.

Under an argon atmosphere, Intermediate 1 (15 g) obtained in Reference Example 1 is stirred with metal sodium (0.15 g) at 80 ° C. for 24 hours. Subsequently, 1,3,5-trisbromomethylbenzene (0.8 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 35 hours. Thereafter, the product was washed with water and subjected to 3 fractions by column chromatography to obtain Compound 1 (5 g) as a second fraction.
Compound 1 was a colorless and transparent liquid, and the density at 20 ° C. was 1.7 g / cm ³ . The identification result of the compound 1 performed using NMR is shown.

Compound 1
¹⁹ F-NMR
δ = −86.4 ppm
_{[18F, -C F 2 CF 2 CH} 2 OCH 2 CH (OH) CH 2 OCH 2 CF 2 C F 2 O -, - C F 2 CF 2 CH 2 OH ],
δ = −86.2 ppm
_{[6F, (- C F 2 CF} 2 CH 2 OCH 2) 3 -C 6 H 3 ],
δ = −83.7 ppm
[134F, —C F ₂ CF ₂ C F ₂ O—],
δ = -129.7 ppm
_{[67F, -CF 2 C F 2 CF} 2 O- ],
δ = -127.5 ppm
_{[6F, -CF 2 C F 2 CH} 2 OH ],
δ = −124.3 ppm
_{[12F, -CF 2 C F 2 CH} 2 OCH 2 CH (OH) CH 2 OCH 2 C F 2 CF 2 O- ],
δ = -123.6 ppm
_{[6F, (- CF 2 C F} 2 CH 2 OCH 2) 3 -C 6 H 3 ],
z = 5.6

¹ H-NMR
δ = 3.85 ppm
_{[6H, (- CF 2 CF 2} C H 2 OCH 2) 3 -C 6 H 3 ],
δ = 4.18 ppm
_{[6H, -CF 2 CF 2 C H} 2 OH ]
δ = 4.50 ppm
_{[24H, -CF 2 CF 2 C H} 2 OC H 2 CH (OH) C H 2 OC H 2 CF 2 CF 2 O- ],
δ = 4.63 ppm
_{[6H, (- CF 2 CF 2} CH 2 OC H 2) 3 -C 6 H 3 ],
δ = 7.37 ppm
_{[3H, (- CF 2 CF 2} CH 2 OCH 2) 3 -C 6 H 3 ],

Example 2
Synthesis of (HO—CH ₂ —R ² —CH ₂ —O—CH ₂ ) ₃ —R ¹ (Compound 2) where R ¹ is a group represented by the following formula (a), and R ² is — _{CF 2 CF 2 O (CF 2} CF 2 CF 2 O) z CF 2 CF 2 - is.

Under an argon atmosphere, perfluoropolyether (50 g) represented by HOCH ₂ —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —CH ₂ OH was added to metallic sodium (0.5 g). And stir at 80 ° C. for 24 hours. Subsequently, 1,3,5-trisbromomethylbenzene (2.7 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 48 hours. Then, it was washed with water and subjected to 3 fractions by column chromatography to obtain Compound 2 (17 g) as a second fraction.
Compound 2 was a colorless and transparent liquid, and the density at 20 ° C. was 1.6 g / cm ³ . The identification result of the compound 2 performed using NMR is shown.

Compound 2
¹⁹ F-NMR
δ = −86.4 ppm
[6F, —C F ₂ CF ₂ CH ₂ OH],
δ = −86.2 ppm
_{[6F, (- C F 2 CF} 2 CH 2 OCH 2) 3 -C 6 H 3 ],
δ = −83.7 ppm
[126F, —C F ₂ CF ₂ C F ₂ O—],
δ = -129.7 ppm
_{[63F, -CF 2 C F 2 CF} 2 O- ],
δ = -127.5 ppm
_{[6F, -CF 2 C F 2 CH} 2 OH ],
δ = -123.6 ppm
_{[6F, (- CF 2 C F} 2 CH 2 OCH 2) 3 -C 6 H 3 ],
z = 10.5

¹ H-NMR
δ = 3.85 ppm
_{[6H, (- CF 2 CF 2} C H 2 OCH 2) 3 -C 6 H 3 ],
δ = 4.18 ppm
_{[6H, -CF 2 CF 2 C H} 2 OH ]
δ = 4.63 ppm
_{[6H, (- CF 2 CF 2} CH 2 OC H 2) 3 -C 6 H 3 ],
δ = 7.37 ppm
_{[3H, (- CF 2 CF 2} CH 2 OCH 2) 3 -C 6 H 3 ],

Example 3
Synthesis of (HO—CH ₂ —R ² —CH ₂ —O—CH ₂ ) ₆ —R ¹ (Compound 3) Here, R ¹ is a group represented by the following formula (b), and R ² is — _{CF 2 CF 2 O (CF 2} CF 2 CF 2 O) z CF 2 CF 2 - is.

Under an argon atmosphere, perfluoropolyether (50 g) represented by HOCH ₂ —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —CH ₂ OH was added to sodium metal (0.9 g). And stir at 80 ° C. for 24 hours. Subsequently, 1,2,3,4,5,6-hexakisbromomethylbenzene (6.4 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 48 hours. Then, it refine | purified by water washing and column chromatography, and the compound 3 (13g) was obtained.
Compound 3 was a colorless and transparent liquid, and the density at 20 ° C. was 1.6 g / cm ³ . The identification result of the compound 3 performed using NMR is shown.

Compound 3
¹⁹ F-NMR
δ = −86.4 ppm
[12F, —C F ₂ CF ₂ CH ₂ OH],
δ = −86.2 ppm
_{[12F, (- C F 2 CF} 2 CH 2 OCH 2) 6 -C 6 ],
δ = −83.7 ppm
[144F, —C F ₂ CF ₂ C F ₂ O—],
δ = -129.7 ppm
_{[72F, -CF 2 C F 2 CF} 2 O- ],
δ = -127.5 ppm
_{[12F, -CF 2 C F 2 CH} 2 OH ],
δ = -123.6 ppm
_{[12F, (- CF 2 C F} 2 CH 2 OCH 2) 6 -C 6 ],
z = 6.0

¹ H-NMR
δ = 3.85 ppm
_{[12H, (- CF 2 CF 2} C H 2 OCH 2) 6 -C 6 ],
δ = 4.18 ppm
_{[12H, -CF 2 CF 2 C H} 2 OH ]
δ = 4.63 ppm
_{[12H, (- CF 2 CF 2} CH 2 OC H 2) 6 -C 6 ],

Example 4
Synthesis of [HO—CH ₂ —R ² —CH ₂ O—CH ₂ CH (OH) CH ₂ —O—CH ₂ —R ² —CH ₂ —O—CH ₂ ] ₃ —R ¹ (Compound 4) , R ¹ is a group represented by the following formula (a), and R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ —.

Under an argon atmosphere, Intermediate 4 (15 g) obtained in Reference Example 2 is stirred with metal sodium (0.15 g) at 80 ° C. for 24 hours. Subsequently, 1,3,5-trisbromomethylbenzene (0.8 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 35 hours. Thereafter, the product was washed with water and subjected to fractionation by column chromatography to obtain Compound 4 (5 g) as a second fraction.
Compound 4 was a colorless and transparent liquid, and the density at 20 ° C. was 1.7 g / cm ³ . The identification result of the compound 4 performed using NMR is shown.

Compound 4
¹⁹ F-NMR
δ = −52.1 ppm, −53.7 ppm, −55.4 ppm
[64F, -OC _F 2 O-],
δ = -77.9 ppm, -79.9 ppm
_{[6F, (- C F 2 CH} 2 OCH 2) 3 -C 6 H 3 ],
δ = −78.2, −80.2 ppm
[12F, —C F ₂ CH ₂ OCH ₂ CH (OH) CH ₂ OCH ₂ C F ₂ O—],
δ = −81.3 ppm, −83.3 ppm
[6F, —C F ₂ CH ₂ OH],
δ = −89.1 ppm, −90.7 ppm
_{[137F, -OC F 2 C F 2} O- ]
x = 5.7 y = 5.3

¹ H-NMR
δ = 3.85 ppm
_{[6H, (- CF 2 C H} 2 OCH 2) 3 -C 6 H 3 ],
δ = 4.18ppm
_[6H, -CF 2 _{C H} 2 OH]
δ = 4.50 ppm
_{[24H, -CF 2 C H 2 OC} H 2 CH (OH) C H 2 OC H 2 CF 2 O- ],
δ = 4.63 ppm
_{[6H, (- CF 2 CH 2} OC H 2) 3 -C 6 H 3 ],
δ = 7.37 ppm
_{[3H, (- CF 2 CH 2} OCH 2) 3 -C 6 H 3 ],

Example 5
Synthesis of (HO—CH ₂ —R ² —CH ₂ —O—CH ₂ ) ₃ —R ¹ (Compound 5) where R ¹ is a group represented by the following formula (a), and R ² is — _{CF 2 O (CF 2 CF 2} O) x (CF 2 O) y CF 2 - is.

In an argon atmosphere, perfluoropolyether (50 g) represented by HOCH ₂ —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ —CH ₂ OH was converted to metallic sodium (0.5 g). And stir at 80 ° C. for 24 hours. Subsequently, 1,3,5-trisbromomethylbenzene (2.7 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 48 hours. Thereafter, the product was washed with water and subjected to 3 fractions by column chromatography to obtain Compound 5 (14 g) as a second fraction.
Compound 5 was a colorless and transparent liquid, and the density at 20 ° C. was 1.7 g / cm ³ . The identification result of the compound 5 performed using NMR is shown.

Compound 5
¹⁹ F-NMR
δ = −52.1 ppm, −53.7 ppm, −55.4 ppm
[56F, —OC F ₂ O—],
δ = -77.9 ppm, -79.9 ppm
_{[12F, (- C F 2 CH} 2 OCH 2) 3 -C 6 H 3 ],
δ = −81.3 ppm, −83.3 ppm
[6F, —C F ₂ CH ₂ OH],
δ = −89.1 ppm, −90.7 ppm
[122F, —OC F ₂ C F ₂ O—]
x = 10.2 y = 9.3

¹ H-NMR
δ = 3.85 ppm
_{[6H, (- CF 2 C H} 2 OCH 2) 3 -C 6 H 3 ],
δ = 4.18ppm
_[6H, -CF 2 _{C H} 2 OH]
δ = 4.63 ppm
_{[6H, (- CF 2 CH 2} OC H 2) 3 -C 6 H 3 ],
δ = 7.37 ppm
_{[3H, (- CF 2 CH 2} OCH 2) 3 -C 6 H 3 ],

Example 6
Synthesis of (HO—CH ₂ —R ² —CH ₂ —O—CH ₂ ) ₆ —R ¹ (Compound 6) where R ¹ is a group represented by the following formula (b), and R ² is — _{CF 2 O (CF 2 CF 2} O) x (CF 2 O) y CF 2 - is.

In an argon atmosphere, perfluoropolyether (50 g) represented by HOCH ₂ —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ —CH ₂ OH was converted to metallic sodium (0.9 g). And stir at 80 ° C. for 24 hours. Subsequently, 1,2,3,4,5,6-hexakisbromomethylbenzene (6.4 g) and 3M HFE7300 are added dropwise thereto and stirred at 80 ° C. for 48 hours. Then, it refine | purified by water washing and column chromatography, and the compound 6 (10g) was obtained.
Compound 6 was a colorless and transparent liquid, and the density at 20 ° C. was 1.7 g / cm ³ . The identification result of the compound 6 performed using NMR is shown.

Compound 6
¹⁹ F-NMR
δ = −52.1 ppm, −53.7 ppm, −55.4 ppm
[65F, —OC F ₂ O—],
δ = -77.9 ppm, -79.9 ppm
_{[12F, (- C F 2 CH} 2 OCH 2) 6 -C 6 ],
δ = −81.3 ppm, −83.3 ppm
[12F, —C F ₂ CH ₂ OH],
δ = −89.1 ppm, −90.7 ppm
[134F, —OC F ₂ C F ₂ O—]
x = 5.6 y = 5.2

¹ H-NMR
δ = 3.85 ppm
_{[12H, (- CF 2 C H} 2 OCH 2) 6 -C 6 ],
δ = 4.18 ppm
_[12H, -CF 2 _{C H} 2 OH]
δ = 4.63 ppm
_{[12H, (- CF 2 CH 2} OC H 2) 6 -C 6 ],

Example 7
Measurement of Monomolecular Film Thickness and Diffusion Coefficient As described in Non-Patent Document 2, the monomolecular film thickness (film thickness per molecule) and the diffusion coefficient of the lubricant applied on the magnetic disk This is confirmed when the diffusion behavior of the lubricant is observed with an ellipsometer. The monomolecular film thickness is obtained as the film thickness of the terrace portion of the lubricant film. The diffusion coefficient is calculated from the following formula using the movement distance (L) of the lubricant after T time.

Journal of Tribology, October 2004, vol. 126, page 751

Diffusion coefficient (mm ² / s) = L ² / T

Specifically, the compounds 1 to 3 synthesized in Examples 1 to 3 are dissolved in Vertrel-XF manufactured by DuPont. The concentrations of compounds 1 and 3 in this solution are both 0.1% by weight. A part (about ¼) of a 2.5 inch diameter magnetic disk is immersed in this solution and pulled up at a speed of 4 mm / s, whereby a part where compounds 1 to 3 are applied as a lubricating layer and a part where it is not applied A disk made of The average film thickness of the applied part was 32 mm.
Immediately after producing the above disk, it is mounted on an ellipsometer, and the change in film thickness near the boundary between the coated part and the non-coated part is measured at a constant time under a temperature condition of 50 ° C. A monomolecular film thickness of the lubricant was obtained as the film thickness. Furthermore, the diffusion coefficient was obtained from the moving distance of the lubricating layer. For comparison, Compound 7 having a hydroxyl group in the molecular chain and at the molecular end was used.

HO— (CH ₂ —R ³ —CH ₂ O—E—O) _s —CH ₂ —R ³ —CH ₂ —OH (Compound 7)
E is a group represented by —CH ₂ —CH (OH) —CH ₂ —. R ³ is —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _t CF ₂ CF ₂ —. s is 5 and t is 6.0.

  Table 1 shows the number average molecular weight, monomolecular film thickness, and diffusion coefficient of Compounds 1 to 3 and 7. From these results, the perfluoropolyether compound having an aromatic group and a hydroxyl group of the present invention shows an equivalent monomolecular film thickness and is higher than that of the compound 7 having a hydroxyl group in the molecular terminal and molecular chain. It was confirmed to show a diffusion coefficient.

Example 8
Production of Magnetic Disk Compound 1 obtained in Example 1 is dissolved in Vertrel-XF manufactured by DuPont. The concentration of Compound 1 in this solution is 0.1% by weight. A 2.5 inch diameter magnetic disk was immersed in this solution for 1 minute and pulled up at a speed of 2 mm / s. Thereafter, it was dried at 150 ° C. for 10 minutes, and the film thickness of the applied compound was measured by FT-IR. As a result, a magnetic disk having the compound of the present invention showing a monomolecular film thickness comparable to that of a compound having a hydroxyl group in the molecular end and molecular chain capable of reducing the film thickness per molecule and having a high diffusion coefficient is produced. It was confirmed that it was possible.

  The present invention can provide a novel perfluoropolyether compound having an aromatic group and a hydroxyl group, a lubricant containing the compound, and a magnetic disk using the same.

DESCRIPTION OF SYMBOLS 1 Support body 2 Recording layer 3 Protective layer 4 Lubrication layer

Claims (6)

The compound represented by Formula (1).
[HO— (CH ₂ —R ² —CH ₂ O—AO) _n —CH ₂ —R ² —CH ₂ —O—CH ₂ ] _p —R ¹ (1)
In the formula, n is an integer of 0 to 6, and A is a group represented by —CH ₂ CH (OH) CH ₂ —. R ¹ is _{C 6 H 6-p, C} 6 H 5-q -O-C 6 H 5-r, aromatic group _C 10 _{H 8-p.} p is an integer of 3-6. q and r are each an integer of 0 or more, and p = q + r. R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ — or —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —. x and y are real numbers of 0 to 30, respectively. z is a real number of 1-30. The compound according to claim 1, wherein x and y are each 0 to 20, and z is 1 to 20. A lubricant containing a compound of formula (1).
[HO— (CH ₂ —R ² —CH ₂ O—AO) _n —CH ₂ —R ² —CH ₂ —O—CH ₂ ] _p —R ¹ (1)
In the formula, n is an integer of 0 to 6, and A is a group represented by —CH ₂ CH (OH) CH ₂ —. R ¹ is _{C 6 H 6-p, C} 6 H 5-q -O-C 6 H 5-r, aromatic group _C 10 _{H 8-p.} p is an integer of 3-6. q and r are each an integer of 0 or more, and p = q + r. R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ — or —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —. x and y are real numbers of 0 to 30, respectively. z is a real number of 1-30. The lubricant according to claim 3, wherein x and y are each 0 to 20, and z is 1 to 20. A magnetic disk having at least a recording layer and a protective layer formed on a support and having a lubricating layer on the surface thereof, wherein the lubricating layer contains a compound represented by the following formula (1).
[HO— (CH ₂ —R ² —CH ₂ O—AO) _n —CH ₂ —R ² —CH ₂ —O—CH ₂ ] _p —R ¹ (1)
In the formula, n is an integer of 0 to 6, and A is a group represented by —CH ₂ CH (OH) CH ₂ —. R ¹ is _{C 6 H 6-p, C} 6 H 5-q -O-C 6 H 5-r, aromatic group _C 10 _{H 8-p.} p is an integer of 3-6. q and r are each an integer of 0 or more, and p = q + r. R ² is —CF ₂ O (CF ₂ CF ₂ O) _x (CF ₂ O) _y CF ₂ — or —CF ₂ CF ₂ O (CF ₂ CF ₂ CF ₂ O) _z CF ₂ CF ₂ —. x and y are real numbers of 0 to 30, respectively. z is a real number of 1-30. 6. The magnetic disk according to claim 5, wherein x and y are each 0 to 20, and z is 1 to 20.

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