JP2962033B2 - Fluorinated alcohol, method for producing the same, and magnetic recording medium having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing alcohol useful as a lubricant, a surfactant, a release agent, a rust inhibitor and the like for precision machines and precision parts requiring high-precision lubricity and its production. A method and a magnetic recording medium having the same.

[0002]

2. Description of the Related Art With the miniaturization and high precision of mechanical devices and parts, the lubrication mode of sliding parts thereof has also shifted from fluid lubrication to boundary lubrication. In particular, in the case of electronic devices and electronic components such as VTRs and magnetic disks, the use of a ferromagnetic metal thin film for the purpose of improving the recording accuracy enables high-precision lubrication for sliding between the magnetic tape or magnetic disk and the magnetic head. Is needed. For example, in the case of vapor-deposited tapes and hard disks, the lubricant layer on the surface of the magnetic layer has only a few lubricant layers in order to minimize the spacing loss between the magnetic recording medium and the magnetic head while increasing the output while ensuring durability and reliability. It is formed to have a thickness of 10 °. Therefore, development of an organic compound having excellent lubricity as a material for forming the lubricant layer is an important issue.

As a lubricant for a metal thin film type magnetic recording medium, a monocarboxylic acid having a fluoroalkyl ether group represented by the formula (3) is excellent in compatibility with a metal thin film.
Numerous proposals have been made (for example, see JP-A-58-41).
438, JP-A-59-127230 and JP-A-62-58414).

[0004]

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Here, R ₅ represents a fluoroalkyl ether group. Further, as a recent conventional example, there is a perfluoropolyether ester of a monocarboxylic acid represented by the following formula (4) (JP-A-2-49218).

[0006]

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Here, R ₆ represents a perfluoropolyether group, R ₇ represents an aliphatic alkyl group, and n is a natural number of 1 or more and 6 or less.

[0008]

However, the lubricant of a monoalkyl carboxylic acid having a fluoroalkyl ether group represented by the above chemical formula (3) has poor lubricity in a high-humidity environment. However, there is a problem that the lubricant of the perfluoropolyether ester of a monocarboxylic acid has reduced lubricity in a low humidity environment.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a substance which does not lose lubricity even in a low humidity environment.

[0010]

The substance of the present invention for achieving the above object is a fluorinated alcohol represented by the general formula (5).

[0011]

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Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl ether group, and n is 0 or 1.

[0013]

The fluorinated alcohol of the present invention has a fluoroalkyl ether group and an aliphatic hydrocarbon group, that is, an aliphatic alkyl group or an aliphatic alkenyl group, and a specific polar group in the same molecule. Number 100-3000
Because of the degree, the effect of the polar group is sufficiently exhibited, and the polar group strongly adheres to the surface of the metal thin film or the surface of the protective film and the surface of the magnetic head. Further, the fluoroalkyl ether group is exposed to the surface and contributes to lowering the energy of the surface, and forms a non-adhesive surface. Further, the aliphatic hydrocarbon group is a flexible carbon-carbon bond chain, and exhibits good lubricity because it is oriented by a moderate intermolecular interaction with the hydrocarbon chain of another adjacent molecule. And, due to the synergistic effect of each of these groups, good lubricity is exhibited in a low humidity environment.

[0014]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be specifically described.

The substance of this embodiment is represented by the following formula (Chemical formula 6), and its starting material is the one represented by the formula (Chemical formula 7). The substance represented by the formula (7) is synthesized from an alkyl succinic anhydride and a fluoroalkyl ether (Japanese Patent Application No. 2-337983).

[0016]

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[0017]

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[0018] (Formula 6) will be described in comparison with the general formula of the material (of 5), C ₁₈ aliphatic alkyl group R ₁
It has H ₃₇ (octadecyl) and has a fluoroalkyl ether group having 11 carbon atoms bonded to fluorine as R ₂ .

Next, a method for producing the substance represented by the formula (6) will be described. 100.1 g of an alkylcarboxylic acid having a fluoroalkyl ether group represented by the chemical formula (7) as a starting material
(0.10 mol) and 300 ml of anhydrous tetrahydrofuran in 1 lit. And then flowed with dried high-purity nitrogen for 1 minute.
mol / lit. Of borane tetrahydrofuran complex (catalyst) in tetrahydrofuran (THF) 300 ml
Was added dropwise in about 2 hours. Subsequently, stirring was continued for 5 hours under ice cooling to complete the reaction. After completion of the reaction, the reaction solution was hydrolyzed by carefully dropping 100 ml of distilled water under ice-cooling. Next, 100 ml of 3N hydrochloric acid was added, and the solution was repeatedly washed with distilled water until the pH reached 7, and then the solution was dried over anhydrous sodium sulfate. Next, THF was distilled off, and the reaction mixture was made into an propyl ether solution, and then cooled to 0 ° C. to remove a reaction by-product. Further, the reaction product was converted to Asahicycline AK in Freon solvent 225.
-225 (manufactured by Asahi Glass) solution was subjected to the same treatment to remove reaction by-products, and 35 g of a white solid having a melting point of 50 ° C. (yield 3
5%). This white solid was analyzed by infrared spectroscopy (IR),
Gel permeation chromatography (GPC) and organic mass spectrometry (FD-MS) revealed that the starting material was free from starting materials and by-products and was a fluorine-containing alcohol represented by the formula (Formula 6).

IR: 3330 cm of alcohol^-1Absorption pi
Appeared, 1705cm of carboxylic acid ^-1Absorption peak disappearance
Destruction.

GPC: no starting material detected. FD-M
S: Main peak at m / e 987.

(Embodiment 2) Next, a second embodiment of the present invention will be specifically described.

The substance of this example is represented by the following formula (Chem. 8), and its starting material is the one represented by the formula (Chem. 9).

[0024]

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[0025]

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Next, a method for producing the substance represented by the formula (8) will be described. Compound (109.2 g, 0.10 mol) of an alkylcarboxylic acid having a fluoroalkyl ether group represented by the following formula (Chem. 9) and 300 ml of anhydrous tetrahydrofuran were added to a 1 lit. After flowing high-purity nitrogen dried for 1 minute, 300 ml of a 1 mol / l borane tetrahydrofuran complex (catalyst) solution in 300 ml of tetrahydrofuran was added dropwise over about 2 hours while stirring under ice cooling. Subsequently, stirring was continued for 5 hours under ice cooling to complete the reaction. After completion of the reaction, the reaction solution was hydrolyzed by carefully dropping 100 ml of distilled water under ice-cooling. Next, 100 ml of 3N hydrochloric acid was added, and the solution was repeatedly washed with distilled water until the pH reached 7, and then the solution was dried over anhydrous sodium sulfate. Next, tetrahydrofuran was distilled off, and the reaction mixture was converted into an isopropyl ether solution, and then cooled to 0 ° C. to remove a reaction by-product. Further, the reaction product was used as a solution of a chlorofluorocarbon solution 225 to remove a reaction by-product by the same treatment, thereby obtaining 42 g (yield: 38%) of a white solid having a melting point of 40 ° C. By IR, GPC and FD-MS, this white solid was found to be a fluorinated alcohol represented by the formula (Formula 8) containing no starting materials and by-products.

IR: appearance of absorption peak at 3380 cm ^-1 for alcohol, disappearance of absorption peak at 1705 cm ^-1 for carboxylic acid.

GPC: no starting material detected. FD-M
S: Main peak at m / e 1078.

(Embodiment 3) Next, an embodiment of the magnetic recording medium of the present invention will be specifically described.

The non-magnetic support of the magnetic recording medium of the present embodiment has several granular projections (average height 70 °, diameter 1 μm) with a gentle gradient due to silica fine particles added in the polyester film per 100 μm ² surface. In addition, on the surface of the polyester film, in which relatively large protrusions due to the fine particles due to the polymerization catalyst residue are reduced as much as possible, steep mountain-like protrusions using silica colloid particles having a diameter of 150 mm as nuclei and an ultraviolet-curable epoxy resin as a binder. 1mm ² per
What was formed so that it might be × 10 ⁷ pieces was used. Then, a Co—Ni ferromagnetic film (Ni content: 20%, film thickness: 100%) is formed on the non-magnetic support by a continuous vacuum oblique deposition method.
0 °) was provided in the presence of trace amounts of oxygen. The oxygen content in the ferromagnetic film was 5% in atomic fraction.

Next, a fluorine-containing alcohol (formula 6) is applied on the ferromagnetic film so as to have an amount of 10 mg per 1 m ² to form a lubricant layer, and then cut into a predetermined width. Thus, a magnetic tape was produced. 5% of the magnetic tape at 23 ℃
Measure the output characteristics during repeated running on a commercially available VCR in an RH environment. The RF output is 3 dB from the initial value.
The number of times of running before the output decreased or the output began to change was determined.

(Example 4) A magnetic tape was prepared from the magnetic tape of Example 3 using (formula 8) instead of (formula 6), and the same test was performed.

(Embodiment 5) The magnetic tape of Embodiment 3
Therefore, instead of (Chem. 6), a known lubricant C ₇F_Fifteen
C_TwoH_FourNHC₁₄H₂₉Used a mixture of 2: 1 by weight.
A similar test was performed using a magnetic tape.

Table 1 shows the test results of the above examples. The lubricants of Conventional Examples 1, 2, 3 and 4 in the table are (Chem. 10), (Chem. 11), (Chem. 12) and (Chem. 1), respectively.
This is shown in 3).

[0035]

[Table 1]

[0036]

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[0037]

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[0038]

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[0039]

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From Table 1, it is clear that all of the magnetic tapes having the lubricant layer containing the fluorinated alcohol of the present invention have excellent repetition running durability in low humidity compared to the conventional example.

(Embodiment 6) Next, another embodiment of the magnetic recording medium of the present invention will be specifically described.

The non-magnetic support of the magnetic recording medium of the present embodiment is prepared by plating a surface of an Al alloy plate having a diameter of 95 mm and a thickness of 1.2 mm with a non-magnetic Ni-P alloy having a thickness of 25 μm, and performing texture processing to obtain an average. A projection having a roughness of 50 ° and a maximum height of 300 ° was used. 1300mm thick Cr by sputtering on non-magnetic Ni-P alloy plating
Forming a base and a ferromagnetic film of Co-Ni with a thickness of 600 °;
Further, a sample A in which a 200-mm-thick graphite protective film was formed on the ferromagnetic film by a sputtering method. A sample B was prepared by forming a diamond-like carbon protective film having a thickness of 50 ° by a plasma CVD method instead of the graphite protective film. Next, a fluorine-containing alcohol (Chemical Formula 6) was applied on the protective films of these samples so as to have an amount of 10 mg per 1 m ² , and a lubricant layer was provided to produce a magnetic disk. The magnetic disk was subjected to a CSS (contact start / stop) durability test under an environment of 23 ° C. and 5% RH, and the durability was determined by the number of CSSs when the friction coefficient exceeded 1.0 or the number of CSSs when a head crash occurred. Sex was determined.

(Example 7) A magnetic disk was prepared from the magnetic disk of Example 6 using (formula 8) instead of (formula 6), and the same test was performed.

(Embodiment 8) A magnetic disk was prepared from the magnetic disk of Example 6 using the same lubricant as in Example 5 instead of (Formula 6), and the same test was performed.

The test results of the above examples are shown in (Table 2). The lubricants of Conventional Examples 5, 6, 7 and 8 in the table are (Chemical Formula 10), (Chemical Formula 11), (Chemical Formula 12) and (Chemical Formula 1), respectively.
This is shown in 3).

[0046]

[Table 2]

From Table 2, it is apparent that all the magnetic disks having the lubricant layer containing the fluorinated alcohol of the present invention have better CSS durability in low humidity than the conventional example.

In the examples, a mixture of the substances of the formulas (6), (8) and (6) with a known lubricant has been described. However, the substances of the formulas (14) and (15) A similar effect can be obtained with a mixture of the above-mentioned substance and a known lubricant.

[0049]

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[0050]

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In the fluoroalkyl ether group R ₂ of the substances of the examples, the number of carbon atoms bonded to fluorine was 11 in (Chemical Formula 6) and 13 in (Chemical Formula 8). 5
It may be 50. Further, in the examples, R ₁ is an aliphatic alkyl group, but the same effect can be obtained when R ₁ is an aliphatic alkenyl group.

[0052]

As is apparent from the above description, the fluorinated alcohol of the present invention has a low humidity because it has a fluoroalkyl ether group, an aliphatic hydrocarbon group and a specific polar group in the same molecule. It shows an excellent effect that the lubricity does not decrease even under the above environment.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI G11B 5/71 G11B 5/71 // C10N 40:06 40:18 (56) References JP-A-62-92227 (JP, A JP-A-57-175323 (JP, A) JP-A-63-46619 (JP, A) JP-A-1-319589 (JP, A) JP-A-1-187088 (JP, A) 167973 (JP, A) European Patent Application Publication No. 473781 (EP, A1) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 69/675 C07C 67/31 C07C 67/317 C07C 69/73 C10M 105/40 G11B 5/71 CAPLUS (STN) REGISTRY (STN) WPIDS (STN)

Claims (3)

(57) [Claims] 1. A fluorine-containing alcohol represented by the general formula (1). Embedded image Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl ether group,
n is 0 or 1. 2. A ferromagnetic film is provided on a nonmagnetic support, and one or more fluorine-containing alcohols represented by the general formula (1) are directly or through a protective film on the ferromagnetic film. A magnetic recording medium provided with a lubricant layer. 3. A method of reacting a fluorinated alkyl carboxylic acid represented by the general formula (Chem. 2) with a tetrahydrofuran solution of borane tetrahydrofuran complex to reduce a carboxyl group. Production method. Embedded image Here, R ₃ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₄ represents a fluoroalkyl ether group,
n is 0 or 1.