Organic fluorine compound, lubricant, and processing method of magnetic recording medium

Abstract

According to one aspect of the present invention, an organic fluorine compound is represented by a general formula
(R-π-E-CH.sub.2-A-CH.sub.2-E′).sub.n-π′-G  (1B) (where n is an integer of 2 to 5, A is a divalent perfluoropolyether group, π is an arylene group or a single bond, R is an alkenyl group or an alkynyl group, and E and E′ are each independently an ether bond or an ester bond or a group that is represented by a chemical formula
—O—CH.sub.2CH(OH)CH.sub.2O—
π′ is a group in which n+1 hydrogen atoms are separated from benzene, G is an organic group containing a fullerene skeleton, the n number of groups each of which is represented by a general formula
R-π-E-CH.sub.2-A-CH.sub.2-E′-
may be the same or different, and at least one π among the n number of π is an arylene group).

Claims

1. An organic fluorine compound that is represented by a general formula
{(R-π-E-CH.sub.2-A-CH.sub.2-E′).sub.n-π′}.sub.2-G  (1B) where n is an integer of 2 to 5, A is a divalent perfluoropolyether group, π is an arylene group or a single bond, R is an alkenyl group or an alkynyl group, and E and E′ are each independently an ether bond or an ester bond or a group that is represented by a chemical formula
—O—CH.sub.2CH(OH)CH.sub.2O— π′ is a group in which n+1 hydrogen atoms are separated from benzene, G is an organic group containing a fullerene skeleton, the n number of groups each of which is represented by a general formula
R-π-E-CH.sub.2-A-CH.sub.2-E′- may be the same or different, and at least one π among then number of π is an arylene group, wherein the organic flourine compound is a compound that is represented by a chemical formula ##STR00010## each of the p and q being an average degree of polymerization and an order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

2. The organic fluorine compound according to claim 1, wherein a carbon number of the A is 1 to 100.

3. The organic fluorine compound according to claim 1, wherein an average formula weight of the A is in a range of 250 to 6000.

4. A lubricant containing the organic fluorine compound according to claim 1.

5. A processing method of a magnetic recording medium comprising: applying the lubricant according to claim 4 to the magnetic recording medium; and irradiating the lubricant applied to the magnetic recording medium with ultraviolet light.

6. The organic fluorine compound according to claim 1, wherein a formula weight of the R.sub.f.sup.1 is approximately 1300.

Description

EXAMPLES

(1) The present invention will be specifically described based on examples in the following. However, the present invention is not limited to the following examples.
(.sup.1H-NMR)

(2) A sample (approximately 10 mg to 30 mg) was dissolved in a CDCl.sub.3/hexafluorobenzene mixed solvent (approximately 0.5 mL) and it was placed in an NMR sample tube having a diameter of 5 mm. Thereafter, .sup.1H-NMR spectrum was measured using a Fourier Transform Nuclear Magnetic Resonance System JNM-EX270 (manufactured by JEOL, Ltd.) at room temperature. At this time, to the CDCl.sub.3/hexafluorobenzene mixed solvent, tetramethylsilane was added as a reference material.

Example 1

(3) Organic fluorine compounds according to the present embodiment were synthesized according to the following synthesis examples.

Synthesis Example 1

Synthesis of Compound 1 (C2) and Compound 2 (C2): [Reaction Formula (7)]

(4) An organic fluorine compound FOMBLIN Zdol whose number average molecular weight (Mn) is approximately 1300 (manufactured by Solvay Specialty Polymers) (3.9 g, 3 mmol), copper (I) iodide (72 mg, 0.38 mmol), ethyl 2-cyclohexanonecarboxylate (0.12 g, 0.71 mmol), and 4-allyliodobenzene (0.62 g, 2.6 mmol) were mixed, thereafter, while stirring, cesium carbonate (3.7 g, 11 mmol) was added and stirring was conducted at 100° C. for 18 hours. Next, the reaction mixture was separated by dilute hydrochloric acid (20 mL) and a fluorine-based solvent AK-225 (manufactured by Asahi Glass Co., Ltd) (20 mL), and the aqueous phase was extracted twice by AK-225 (20 mL). After water washing the organic phase, magnesium sulfate was added and it was dried and filtered. Next, the filtrate was concentrated by a rotary evaporator to obtain a crude product (4.5 g) as an orange brown oily substance.

(5) Next, through purification by silica gel column chromatography (developing solvent:hexane-ethyl acetate (9:1 to 5:1)), a compound 2 (C2) was obtained as a colorless oily substance (0.96 g, 0.68 mmol, yield 22%).

(6) ##STR00004##

(7) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(8) It was confirmed by the peaks of .sup.1H-NMR spectrum that the colorless oily substance was the compound 2.

(9) (Compound 2)

(10) Peaks of .sup.1H-NMR spectrum δ[ppm]: 2.01 (s, 1H), 3.34 (d, 2H), 3.93 (br, 2H), 4.31 (br, 2H), 5.02-5.08 (m, 2H), 5.87-6.02 (m, 1H), 6.86 (d, 2H), 7.13 (d, 2H)

Synthesis Example 2

Synthesis of Compound 3 (C3): [Reaction Formula (8)]

(11) The compound 2 (0.32 g, 0.23 mmol) obtained in Synthesis Example 1 and pyridine (36 mg, 0.46 mmol) were added to dichloromethane (25 mL). Thereafter, a dichloromethane (5 mL) solution of trifluoromethanesulfonic anhydride (86 mg, 0.30 mmol) was added dropwise and stirring was conducted at room temperature for 15 hours. Next, the reaction mixture was washed once with pure water (30 mL) and once with a saturated aqueous sodium carbonate solution (30 mL), and then the organic phase was filtered. Next, the filtrate was concentrated with a rotary evaporator to obtain a compound 3 (C3) (0.35 g, 0.22 mmol, yield 96%) as a colorless oily substance.

(12) ##STR00005##

(13) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(14) It was confirmed by the peaks of .sup.1H-NMR spectrum that the colorless oily substance was the compound 3 (C3).

(15) Peaks of .sup.1H-NMR spectrum δ[ppm]: 3.34 (d, 2H), 4.31 (br, 2H), 4.66 (br, 2H), 5.02-5.08 (m, 2H), 5.86-6.02 (m, 1H), 6.86 (d, 2H), 7.13 (d, 2H)

Synthesis Example 3

Synthesis of Compound 4 (C4): [Reaction Formula (9)]

(16) The compound 3 (0.30 g, 0.19 mmol) obtained in Synthesis Example 2 and 2,4,6-trihydroxybenzaldehyde (12 mg, 78 μmol) were added to N,N-dimethylformamide (15 mL). Thereafter, cesium carbonate (88 mg, 0.27 mmol) was added and stirring was conducted at 70° C. for 16 hours. Next, the reaction mixture was cooled to room temperature, concentrated with a rotary evaporator, and then separated using pure water (20 mL) and a fluorine-based solvent AK-225 (manufactured by Asahi Glass Co., Ltd) (20 mL). Next, the aqueous phase was extracted twice with a fluorine-based solvent AK-225 (Asahi Glass Co., Ltd.) (20 mL). After water washing the organic phase, magnesium sulfate was added and it was dried and filtered. Next, the filtrate was concentrated by a rotary evaporator to obtain a reddish brown oily crude product (0.35 g). Next, through purification by silica gel column chromatography (developing solvent:hexane-ethyl acetate (9:1)), a compound 4 (C4) was obtained as a colorless oily substance (0.11 g, 25 μmol, yield 39%).

(17) ##STR00006##

(18) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(19) It was confirmed by the peaks of .sup.1H-NMR spectrum that the colorless oily substance was the compound 4 (C4).

(20) Peaks of .sup.1H-NMR spectrum δ(ppm): 3.34 (d, 6H), 4.28-4.46 (m, 12H), 5.00-5.08 (m, 6H), 5.88-6.01 (m, 3H), 6.82-6.91 (m, 6H), 7.17-7.22 (m, 6H), 10.34 (s, 1H)

Synthesis Example 4

Synthesis of Compound 5 (C5): [Reaction Formula (10)]

(21) The compound 4 (0.11 g, 25 μmol) obtained in Synthesis Example 4 and N-methylglycine (15 mg, 0.17 mmol) were added to hexafluorotetrachlorobutane (6 mL). Thereafter, a o-dichlorobenzene (12 mL) solution of C.sub.60 fullerene (11 mg, 15 μmol) was quickly added. Next, after attaching a Dimroth condenser, it was heated in a hot water bath set at 180° C. and refluxed with stirring for 3 hours. Next, the reaction mixture was cooled to room temperature and then concentrated by a rotary evaporator. Next, it was dissolved in an appropriate amount of tetradecafluorohexane and then filtered. Next, the filtrate was concentrated with a rotary evaporator to obtain a black oily crude product (0.19 g).

(22) Then, after the crude product was placed in a stainless steel pressure container (20 mm in inner diameter×200 mm in depth) having an inlet and an outlet, while keeping the temperature in the pressure vessel at 60° C., using a supercritical phase chromatography pump PU 2086-CO2 (manufactured by JASCO Corporation), supercritical carbon dioxide was fed to the pressure vessel at a flow rate of 5 mL/min. in terms of liquefied carbon dioxide. Next, the pressure in the pressure container was varied in the range of 9 MPa to 16 MPa, and by-products with three or more pyrrolidine rings formed on the fullerene skeleton were extracted and removed. Next, the pressure in the pressure container was increased to 24 MPa and the compound 5 (C5) was extracted as 39 mg of the black oily material (27% yield). Note that under these conditions, a compound in which one pyrrolidine ring is formed on the fullerene skeleton was not extracted.

(23) ##STR00007##

(24) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(25) It was confirmed by the peaks of .sup.1H-NMR spectrum that the black oily substance was the compound 5.

(26) Peaks of .sup.1H-NMR spectrum δ(ppm): 2.72 (brs, 6H), 3.31 (brd, 12H), 4.30 (br, 12H), 4.44 (br, 12H), 4.99-5.08 (m, 12H), 5.88-6.03 (m, 6H), 6.90 (br, 12H), 7.15 (br, 12H)

Example 2

(27) A protective layer made of DLC (Diamond-Like Carbon) was formed on a 2.5-inch glass plank for magnetic disk by a high-frequency magnetron sputtering method using carbon as a target in an Ar gas atmosphere, and a simulated disk was made.

(28) Here, the content of nitrogen atoms in the protective layer of each simulated disk was measured using a scanning X-ray photoelectron spectrometer (XPS/ESCA) PHI Quantera II™ (manufactured by ULVAC-PHI, Inc.), and only simulated disks, which were guaranteed that the content of nitrogen atoms in the protective layer was 1 atom %, were used.

(29) Next, as the lubricant, the compound 5 was dissolved in PF-5060 (tetradecafluorohexane) (manufactured by the 3M Company) and a lubricant solution of 0.01% by mass was prepared.

(30) The lubricant solution was then applied onto the protective layer of the simulated disk using a dipping method. That is, the lubricant solution was applied on the protective layer of the simulated disk by immersing the simulated disk in the lubricant solution placed in the immersion tank of a dipping coating machine and pulling up the simulated disk from the immersion tank. Next, after the surface coated with the lubricant solution was dried, ultraviolet light having wavelengths of 185 nm and 254 nm was irradiated for 2 seconds using a low-pressure mercury lamp EUV200 US-A2 (manufactured by SEN LIGHTS CORPORATION) to form a lubricant layer.

(31) (Average Thickness of Lubricant Layer)

(32) Using a Fourier transform infrared spectrometer Nicolet iS50 (manufactured by Thermo Fisher Scientific K.K), by a high sensitivity reflection method, the average thickness of the lubricant layer was obtained by measuring the intensity of an absorption peak corresponding to a stretching vibration energy of a C—F bond of the infrared absorption spectrum. Here, thicknesses at four points were measured for the lubricant layer, and an average value of these was determined as the average thickness.

(33) (Bonded Ratio of Lubricant Layer)

(34) The simulated disk, whose average thickness of the lubricant layer had been measured, was immersed in an immersion tank containing Vertrel (registered trademark) XF (1,1,1,2,3,4,4,5,5,5,5,5-decafluoropentane) (manufactured by Dupont-Mitsui Fluorochemicals Co., Ltd.) for 10 minutes. Thereafter, the simulated disk was pulled up to wash away lubricant that was not fixed to the protective layer of the simulated disk. Then, after the simulated disk was dried, the average thickness of the lubricant layer was determined in a manner similar to the above.

(35) The ratio of the average thicknesses of the lubricant layer before and after the above process was determined as the bonded ratio.

Comparative Example 1

(36) The average thicknesses and the bonded ratio of the lubricant layer were evaluated similarly to Example 2 with the exception of using an organic fluorine compound FOMBLIN Ztetraol whose number average molecular weight (Mn) is approximately 2000 (manufactured by Solvay Specialty Polymers) (see the chemical formula (4)) instead of the compound 5.

Comparative Example 2

(37) The average thicknesses and the bonded ratio of the lubricant layer were evaluated similarly to Example 2 with the exception of using, instead of the compound 5, a compound 13 (C13) that is represented by the following chemical formula.

(38) ##STR00008##

(39) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(40) Note that the compound 13 was synthesized using a S.sub.N2 reaction from an organic fluorine compound FOMBLIN Zdol whose number average molecular weight (Mn) is approximately 1300 (manufactured by Solvay Specialty Polymers) (see the chemical formula (3)) and allyl bromide.

Comparative Example 3

(41) The average thicknesses and the bonded ratio of the lubricant layer were evaluated similarly to Example 2 with the exception of using, instead of the compound 5, a compound 14 (C14) that is represented by the following chemical formula.

(42) ##STR00009##

(43) Here, p and q are an average degree of polymerization and the order of (CF.sub.2O) and (CF.sub.2CF.sub.2O) in R.sub.f.sup.1 is arbitrary.

(44) Note that the compound 14 was synthesized using a method similar to that of the synthesis example 1 from an organic fluorine compound FOMBLIN Zdol whose number average molecular weight (Mn) is approximately 1300 (manufactured by Solvay Specialty Polymers) (see the chemical formula (3)) and iodobenzene.

(45) Table 1 indicates the evaluation result of the average thicknesses of the lubricant layers and the bonded ratios.

(46) TABLE-US-00001 TABLE 1 AVERAGE THICKNESS OF LUBRICANT LAYER [nm] BEFORE AFTER ORGANIC BEING BEING BONDED FLUORINE PRO- PRO- RATIO COMPOUND CESSED CESSED [%] Example 2 COMPOUND 1.23 1.08 88 5 Comparative CHEMICAL 0.47 0.12 26 Example 1 FORMULA (4) Comparative COMPOUND 0.34 0.22 65 Example 2 13 Comparative COMPOUND 0.75 0.32 43 Example 3 14

(47) From Table 1, it can be seen that the compound 5 used in Example 2 can form a lubricant layer having a sufficient thickness on a protective layer that has not been subjected to a nitriding process and can increase the bonded ratio of the lubricant layer. At this time, it is considered that fixing of the lubricant layer is promoted by irradiating a compound having an alkenyl group or an alkynyl group with ultraviolet light.

(48) In contrast, because the compound that is represented by the chemical formula (4) and the compound 13 used in Comparative Examples 1 and 2 do not have an aromatic ring in the molecule, a lubricant layer having a sufficient thickness cannot be formed on a protective layer to which a nitriding process is not applied.

(49) Note that, from the bonded ratios of the lubricant layers of Comparative Example 1 and Comparative Example 2, it is suggested that fixing of the lubricant layer is promoted by irradiating the compound 13 having an allyl group with ultraviolet light.

(50) In the compound 14 used in Comparative Example 3, the bonded ratio of the lubricant layer is a low value because an alkenyl or an alkynyl group is not directly attached to a phenyl group.

(51) This result shows adsorption of a molecular structure containing an aryl group, in which an alkenyl group or an alkynyl group is directly attached on an aromatic ring, included in the compound 5 used in Example 2 on a protective layer to which a nitriding process is not applied, and the effect of fixing of the lubricant layer by irradiation with ultraviolet light.

INDUSTRIAL APPLICABILITY

(52) According to an organic fluorine compound according to the present embodiment, with respect to a substrate having a protective layer to which a nitriding process is not applied, a lubricant layer having a sufficient thickness can be formed by a dipping method, and by irradiating the lubricant layer with ultraviolet light, fixing of the lubricant layer can be promoted, and as a result, the bonded ratio of the lubricant layer can be increased.

(53) The present international application is based on and claims priority to Japanese Patent Application No. 2017-128567, filed on Jun. 30, 2017, the entire contents of Japanese Patent Application No. 2017-128567 are hereby incorporated herein by reference.