JPH10204033A - Fluorine-containing alkylsuccinic acid diester and magnetic recording medium having the diester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject new compound useful for a magnetic recording medium, etc., which is excellent in traveling, durability and weather resistance, at the same time, capable of holding reliability even under widely ranged environments and free from the loss of lubricity under an environment of low temperature. SOLUTION: A compound of formula I [R<1> is an aliphatic alkyl, etc.; R<2> is a fluoroalkyl; R<3> is O or S; R<4> is S or SC2 H4 S; (m) is an integer of 1-6; (n) is an integer of 1-30; R<5> is an aliphatic alkyl, etc.; R<6> is O or S; (a) is 0, 1; (b) is 0, 1], e.g. a compound of formula II. A compound of formula I is obtained by reacting an alkylsuccinic anhydride such as dodecylsuccinic anhydride with an aliphatic alcohol at 60-100 deg.C under heating and stirring, further reacting the reaction product with a fluoroalkylene oxide-containing fluoroalcohol of formula III (R<2> is a fluoroalkyl; R<3> is O or S), etc., in the presence of a solvent such as normal octane at 60-100 deg.C under heating and stirring, and extracting the residue of reduced pressure distillation of the reaction mixture with an organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel fluorine-containing compound useful as a lubricant for a precision machine, a precision part, a surfactant, a release agent, a rust inhibitor, etc., which require high precision lubrication. The present invention relates to 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 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 density allows sliding between a magnetic recording medium such as a magnetic tape or a magnetic disk and a magnetic head. Has required high-precision lubrication. 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 mm. 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 long-chain carboxylic acid fluoroalkyl ester represented by the following chemical formula (for example, JP-A No. 62-46431) or a chemical formula (4) is used. There is a fluoroalkyl succinate (for example, JP-A-5-128498).

[0004]

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[0005]

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[0006]

However, the above-mentioned (Formula 3)
The lubricant of a long-chain fluoroalkyl carboxylate represented by the formula (1) or the lubricant of a fluoroalkyl succinate represented by the formula (4) has a problem that lubricity is reduced in a low temperature environment.

The present invention solves the above-mentioned conventional problems, and provides a magnetic recording medium which is excellent in running properties, durability and weather resistance, and which can be practically used under a wide range of environmental conditions and maintain its reliability. Aim.

[0008]

In order to achieve the above object, a magnetic recording medium of the present invention comprises a ferromagnetic metal thin film provided on a nonmagnetic support, and a protective film provided on the ferromagnetic metal thin film. And a lubricant layer containing at least one fluorine-containing alkyl succinic diester of the present invention.

The fluorine-containing alkyl succinic acid diester used in the present invention is represented by the following general formula (Chemical Formula 5), wherein the fluoroalkyl terminal group having one fluoroalkylene oxide chain in the same molecule is formed on the surface of the metal thin film or It is exposed on the surface of the protective film and the surface of the magnetic head, contributing to lowering the energy of the surface and forming a non-adhesive surface. Further, the fluoroalkylene oxide chain in the fluorine-containing alkyl succinic diester molecule has a protective effect on the surface of the metal thin film and the surface of the magnetic head.

Further, the fluoroalkylene oxide chain has the effect of softening the rigid fluorine-containing hydrocarbon terminal chain due to the presence of the ether linking group, so that it exhibits good lubricity and achieves both non-adhesiveness and lubricity. .

In addition, the aliphatic hydrocarbon terminal group has a good lubricating property due to its flexible carbon-carbon bonding chain. And, due to the synergistic effect of each of these terminal groups, the magnetic recording medium provided with the lubricant layer containing the fluorine-containing alkyl succinic diester of the present invention has an excellent effect that lubricity does not decrease in a low temperature environment. Can be

[0012]

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Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl group, R ₃ represents —O— or —S—, and R ₄ represents —S— or —S. S
C ₂ H ₄ S—, m is an integer of 1 to 6, and n is 1
R ₅ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₆ represents —O— or —S—, a is 0 or 1, and b is 0 or 1. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine-containing alkyl succinic diester used in the present invention includes a fluoroalkyl terminal group represented by the above general formula (Formula 5) and having one fluoroalkylene oxide chain in the same molecule; The structure has two aliphatic hydrocarbon end groups, ie, an aliphatic alkyl end group or an aliphatic alkenyl end group.

Here, R ₁ in the above (Chemical Formula 5) is suitably a carbon number of 6 to 30, preferably 10 to 24, and if the carbon number is less than 6 or more than 30, the lubricity is reduced. R ₂
Is a fluoroalkyl group having 1 to 30, preferably 1 to 8 carbon atoms, m is an integer of 1 to 6, n is an integer of 1 to 30, and preferably 1 to 8; , N are out of these ranges, the lubricity and storage reliability decrease. R ₃ is —O— or —S—, and R ₄ is
-S- or -SC ₂ H ₄ is S-, carbon atoms as R ₅ is 6 to 30, preferably is suitably 10 to 24, lubricity is lowered when the number of carbon atoms exceeds 6, or less than 30 . As R _6-
O- or -S-, a is 0 or 1, b is 0
Or 1.

This fluorine-containing alkyl succinic diester is represented by the following general formula (Formula 6) using a fluoroalkyl alcohol having a fluoroalkylene oxide group or a fluoroalkyl thiol having a fluoroalkylene oxide group as a starting material, wherein R ₂ is a carbon atom. Is 1 to 30, preferably 1 to
A fluoroalkyl group of 8; m is an integer of 1 to 6;
Is an integer of 1 to 30, preferably 1 to 8, and R ₃ is —O— or —S—.

[0017]

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[0018] wherein R ₂ represents a fluoroalkyl group, R ₃
Represents -O- or -S-, m is an integer of 1 to 6,
n is an integer of 1 to 30.

This lubricant layer is prepared by adding a fluorinated alkyl succinic diester represented by the general formula (5) or a fluorinated alkyl succinic diester and other lubricants, rust preventives, extreme pressure agents and the like. On the layer. The mixing ratio is suitably at least 40 mol%, preferably at least 60 mol%, based on the total amount of the mixture. If the amount of the fluorinated alkyl succinic diester is less than 40 mol%, the effect of the present invention is hardly obtained. Its abundance surface 1 m ² per 0.05 to 100 mg, preferably suitable range of 0.1 to 50 mg. As the other lubricant and rust preventive, a fluorine-containing compound is preferable, and a liquid fluorine-containing compound is more preferable. The addition amount is preferably in the range of 0 to 60%, preferably 0 to 40%.
If the content of the fluorinated alkyl succinic diester is less than 40%, it is difficult to obtain the effects of the present invention.

As the protective film, a carbon thin film in an amorphous state, a graphite state, a diamond state, a mixed state thereof, or a laminated state obtained by a method such as sputtering or plasma CVD can be applied.
50-500 ° is preferred.

The process for producing the fluorinated alkyl succinic diester used in the present invention includes alkyl succinic anhydride or alkenyl succinic anhydride or alkylthio succinic anhydride or alkenylthio succinic anhydride and an aliphatic alcohol, ie, an alkyl alcohol or alkenyl thiol or An aliphatic thiol, that is, an alkyl thiol or an alkenyl thiol is mixed and heated and stirred.
The heating temperature is 60 to 100 ° C, preferably 80 to 90 ° C. If it is lower than this range, unreacted substances tend to remain, while if it is higher, by-products tend to be formed.

Examples of the alkyl succinic anhydride or alkenyl succinic anhydride or alkylthio succinic anhydride or alkenylthio succinic anhydride that can be used include dodecyl succinic anhydride, tridecyl succinic anhydride, tetradecyl succinic anhydride, pentadecyl succinic anhydride, and hexadecyl anhydride. Succinic acid, heptadecyl succinic anhydride, octadecyl succinic anhydride, nonadecyl succinic anhydride, icosyl succinic anhydride, henicosyl succinic anhydride, docosyl succinic anhydride, dodecenyl succinic anhydride, tridecenyl succinic anhydride, tetradecenyl succinic anhydride, pentadecenyl anhydride Succinic acid, hexadecenyl succinic anhydride, heptadecenyl succinic anhydride, octadecenyl succinic anhydride, nonadecenyl succinic anhydride, icosenyl succinic anhydride, henicocenyl Water succinic, docosenyl succinic anhydride, dodecylthio succinic anhydride, tridecylthio succinic anhydride, tetradecylthio succinic anhydride, pentadecyl thio succinic anhydride, hexadecylthio succinic anhydride,
Heptadecylthio succinic anhydride, otacdecylthio succinic anhydride, nonadecyl succinic anhydride, icosylthio succinic anhydride, henicosylthio succinic anhydride, docosylthio succinic anhydride, dodecenylthio succinic anhydride, tridecenylthio succinic anhydride, tetradecenyl succinic anhydride, pentadecenyl succinic anhydride Ruthiosuccinic anhydride, hexadecenylthiosuccinic anhydride, heptadecenylthiosuccinic anhydride,
There are octadecenylthio succinic anhydride, nonadecenylthio succinic anhydride, icosenylthio succinic anhydride, henicocenylthio succinic anhydride, and docosenylthio succinic anhydride.

Examples of the aliphatic alcohol that can be used include butanol, propanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol and octadecanol. , Nonadecanol.

Next, the fluorinated alkyl succinic acid diester is mixed with a fluoroalkyl alcohol having a fluoroalkylene oxide group or a fluoroalkyl thiol having a fluoroalkylene oxide group, and the mixture is heated and stirred. The heating temperature is 60 to 100 ° C, preferably 80 to 90 ° C. If it is lower than this range, unreacted substances tend to remain, while if it is higher, by-products tend to be formed.

Alkyl succinic anhydride or alkenyl succinic anhydride or alkylthio succinic anhydride or alkenylthio succinic anhydride and an aliphatic alcohol, ie, alkylthio succinic anhydride or alkenylthio succinic anhydride and an aliphatic alcohol, ie, alkyl alcohol or alkenyl alcohol or fatty acid The reaction with the group thiol, i.e., alkyl thiol or alkenyl thiol, conveniently proceeds with heating and stirring in the presence of a solvent.
The solvent includes normal octane and normal heptane.

The fluoroalkylene alcohol with a fluoroalkylene oxide group or the fluoroalkyl thiol with a fluoroalkylene oxide group to be used includes perfluoro-3,7,11-trioxahexadecylmethanol,
Perfluoro-2,5,8,11,14,17,20-heptaoxaheptacosylmethanol, perfluoro-4,9,14-
Trioxatetrasilmethanol, perfluoro-3
7,11-trioxahexadecylmethylthiol, perfluoro-2,5,8,11,14,17,20-heptaoxaheptacosylmethylthiol, perfluoro-4,9,14-
There is trioxatetrasylmethylthiol. The reaction between the fluorinated alkyl succinic diester and the fluoroalkylene oxide-containing fluoroalkyl alcohol or fluoroalkylene oxide-containing fluoroalkylthiol proceeds conveniently when heated and stirred in the presence of a solvent.

The solvent includes normal octane and normal heptane. The molar ratio of the alkyl succinic anhydride, alkenyl succinic anhydride, alkylthio succinic anhydride, or alkenylthio succinic anhydride to the fluoroalkylene oxide-containing fluoroalkyl alcohol or fluoroalkylene oxide-containing fluoroalkylthiol is equimolar.

In order to isolate the target compound from the obtained mixture, the solvent is first removed by evaporation under reduced pressure, and the residue is extracted with an organic solvent to obtain a compound-containing alkyl carboxylic acid diester. This compound can be identified by infrared spectroscopy (IR), gel permeation chromatography (GPC) and organic mass spectroscopy (FD-MS).

[0029]

The embodiments of the present invention will be specifically described below.

Example 1 The chemical formula of the substance of Example 1 is
It is shown by (Formula 7).

[0031]

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The compound of formula (7) will be explained in comparison with the general formula of formula (5). R ₁ is a dodecyl group having 12 carbon atoms and R ₂ is a fluoroalkyl having 5 carbon atoms bonded to fluorine. Wherein m is 3, n is 2, R ₃ is —O—, and R ₅ is
Wherein R ₆ is —O—, a is 0, and b is 0.

Next, a method for producing the substance represented by the formula (7) will be described.

The starting materials are 26.8 g (0.10 mol) of dodecyl succinic anhydride represented by (Chem. 8) and 18.6 g (0.10 mol) of dodecanol represented by (Chem. 9).

[0035]

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[0036]

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The above raw materials and 500 ml of benzene were collected in a 1 liter flask equipped with a stirring blade, and reacted at 80 ° C. for 24 hours. After completion of the reaction, benzene was distilled off, the reaction mixture was dissolved in hexane, and cooled to -10 ° C to remove unreacted dodecyl succinic anhydride. The reaction mixture was further treated as a methanol solution to remove unreacted dodecanol and obtain 45.4 g of a white solid.

Next, 22.7 g of this carboxylic acid monoester was used.
(0.05 mol), 0.9 g of paratoluenesulfonic acid (PTS) (1.5% based on the weight of the raw material) and 300 ml of normal heptane
37.4 g (0.05 mol) of the fluoroalkylenefluxol having a fluoroalkylene oxide group represented by 10) was collected in a 1-liter flask equipped with a water separator and a stirring blade, and the mixture was refluxed.
The reaction was performed for 24 hours.

[0039]

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After completion of the reaction, the reaction solution was repeatedly washed with distilled water until the pH reached 7, and then dried over anhydrous sodium sulfate. Next, normal heptane is distilled off, the reaction mixture is dissolved in methanol, and the mixture is cooled to -10 ° C to remove unreacted carboxylic acid monoester and unreacted fluoroalkylene oxide group-containing fluoroalkyl alcohol, and are colorless and transparent. 59 g of a liquid was obtained. This colorless and transparent liquid was subjected to infrared spectroscopy (IR), gel permeation chromatography (G
PC) and organic mass spectrometry (FD-MS), it was found to be a substance represented by the formula (Chemical formula 7) which does not contain starting materials and by-products. The results of infrared spectroscopy (spectrum) of this compound are shown in FIG. 1, where the horizontal axis represents wavelength (cm- ¹ ) and the vertical axis represents transmittance (%).

IR: Absorption peak of acid anhydride at 1,775 cm- ¹ and absorption peak of alcohol at 3,330 cm- ¹ disappeared, and absorption peaks of esters at 1,735 cm- ¹ and 1,760 cm- ¹ appeared. GPC: Dodecanol, fluoroalkyl alcohol with fluoroalkylene oxide group, dodecyl succinic anhydride and carboxylic acid monoester were not detected. FD-MS; main peak at m / e1,202.

In Example 1, the compound represented by the general formula (Formula 7)
R ₁ is a dodecyl group having 12 carbon atoms, R ₂ is a fluoroalkyl group having 5 carbon atoms bonded to fluorine, m is 3,
The production method in the case where n is 2, R ₃ is —O—, R ₅ is a dodecyl group having 12 carbon atoms, _Ra is —O—, a is 0, and b is 0 has been described, In the case where the structure is different from this, the starting material is replaced with a fluoroalkylene oxide-containing fluoroalkyl alcohol, for example, (Chemical Formula 11) or (Chemical Formula 12)
(Formula 13) or (Formula 14) can be similarly produced by using

Further, dodecanol was used as the aliphatic alcohol, but the starting material was changed, for example,
By using (Chemical Formula 16), (Chemical Formula 17) or (Chemical Formula 18) can be similarly produced. Also, dodecyl succinic anhydride was used as the aliphatic alkyl succinic anhydride, but the starting material was changed to an aliphatic alkenyl succinic anhydride, for example,
(Chemical Formula 20) as an aliphatic alkylthio succinic anhydride, for example, (Chemical Formula 21) as an aliphatic alkenylthio succinic anhydride,
For example, by using (Chemical formula 22), (Chemical formula 23) or (Chemical formula 24) or (Chemical formula 25) or (Chemical formula 26) can be similarly produced.

[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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Embodiment 2 Next, embodiments of the magnetic recording medium of the present invention will be described specifically, but the present invention is not limited to these embodiments.

In the non-magnetic support of the magnetic recording medium of this example, there are 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, the relatively large protrusions due to fine particles due to the polymerization catalyst residue are reduced as much as possible on the surface of the polyester film.
Of silica colloid particles as nuclei and steep mountain-like projections using an ultraviolet-curable epoxy resin as a binder were formed so as to be 1 × 10 ⁷ per 1 mm ² . Then, a Co—Ni ferromagnetic thin film (Ni content: 20%, film thickness: 1000 ° C.) was provided on the nonmagnetic support by continuous vacuum oblique deposition in the presence of a small amount of oxygen. The oxygen content in the ferromagnetic film was 5% in atomic fraction.

Next, a plasma CV is formed on the ferromagnetic film.
After forming a diamond-like carbon protective film having a thickness of 50 ° by the method D, the fluorine-containing alkyl succinic diester represented by the formula (7) is formed on the protective film in an amount of 10 mg per 1 m ^2. And a lubricant layer was formed, and then cut to a predetermined width to produce a magnetic tape.

The magnetic tape was placed on a polyacetal resin roller having a diameter of 3 mm in an environment of 5 ° C. and 80% RH.
Reciprocate 300mm length 200mm 300 times at a speed of mm / sec, measure the coefficient of friction of the magnetic tape, and then hang the magnetic tape on a commercially available VCR at 5 ° C and 80% RH. The regeneration life was measured. Still playback life is R
The time was taken until the F output decreased by 10 dB from the initial value.

(Example 3) A magnetic tape was prepared from the magnetic tape of Example 2 using (Formula 13) instead of (Formula 7), and the same test was performed.

(Example 4) In the magnetic tape of Example 2, (Chem. 7) was used instead of (Chem. 7), and a conventionally known lubricant C ₁₇ H _{33 was used.}
A similar test was conducted by preparing a magnetic tape using a mixture of COOC ₂ H ₄ C ₈ F ₁₇ at a weight ratio of 1: 1.

(Example 5) In the magnetic tape of Example 2, a mixture of (Chem. 7) in place of (Chem. 7) and a rust inhibitor (C ₁₈ H ₃₅ O) ₃ P at a weight ratio of 2: 1 was used. The same test was performed using the magnetic tape used.

Table 1 shows the test results of Examples 2 to 5 described above. The lubricants of Conventional Examples 1 and 2 in the table are (Chemical Formula 3),
It is shown in (Formula 4).

[0068]

[Table 1]

From Table 1, it can be seen that all the magnetic tape samples provided with the lubricant layer containing the fluorinated alkyl succinic diester of the present invention have a low coefficient of friction and a more stable running property under a low temperature environment. It is clear that the obtained still life is longer and stable and the lubricity is excellent. On the other hand, it is clear that the magnetic tapes provided with the lubricant layers consisting only of the lubricants of Conventional Examples 1 and 2 have an increased friction coefficient and a reduced still characteristic.

In the examples, (Formula 7), (Formula 13) and (Formula 7)
And a conventionally known lubricant and a mixture of (Chemical formula 7) and a rust preventive agent were described, but (Chemical formula 14), (Chemical formula 17), (Chemical formula 18),
Similar effects can be obtained with the substances of the formulas (24), (25), (26), and (27), and mixtures of these substances with conventionally known lubricants and rust inhibitors.

[0071]

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In the examples, phosphite was described as a rust preventive, but hydrogen phosphite, trithiophosphite, phosphate, thiophosphate,
Similar effects can be obtained with dithiophosphate, trithiophosphate, tetrathiophosphate, phosphonate, and phosphoric amide.

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

The non-magnetic support of the magnetic recording medium of this embodiment has a thickness of 25 μm on a surface of an Al alloy plate having a diameter of 95 mm and a thickness of 1.2 mm.
A non-magnetic Ni-P alloy plating having an average roughness of 50 ° and a maximum height of 300 ° formed by texturing was used. 1300mm thick Cr underlayer and 600mm thick C on non-magnetic Ni-P alloy plating by sputtering.
Sample A was formed by forming a ferromagnetic film of o-Ni and further forming a 200-mm-thick graphite protective film on the ferromagnetic film by a sputtering method. A sample B was prepared by forming a 50-mm-thick diamond-like carbon protective film by a plasma CVD method instead of the graphite protective film. Next, on the protective film of these samples
A fluorine-containing alkyl succinic diester represented by the formula (Formula 7) was applied 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 friction coefficient of the magnetic disk was measured by a drag test in an environment of 5 ° C. and 80% RH, and the magnetic disk was subjected to a CSS (contact start / stop) test in an environment of 5 ° C. and 70% RH. Was performed, and the durability was determined based on the number of CSSs when the friction coefficient exceeded 1.0 or the number of CSSs when a head crash occurred.

Example 7 A magnetic disk was prepared from the magnetic disk of Example 6 using (Formula 13) instead of (Formula 7), and the same test was performed.

(Embodiment 8) A magnetic disk using the same lubricant as that of Embodiment 4 in place of (Chemical Formula 7) was prepared from the magnetic disk of Embodiment 6, and a similar test was performed.

(Example 9) A magnetic disk was prepared from the magnetic disk of Example 6 using the same rust preventive as in Example 5 instead of (Chemical Formula 7), and the same test was performed.

Table 2 shows the test results of Examples 6 to 9 described above. The lubricants of Conventional Examples 3 and 4 in the table are (Chemical Formula 3), respectively.
It is shown in (Formula 4).

[0080]

[Table 2]

From Table 2, it can be seen that all magnetic disks provided with a lubricant layer containing at least one fluorine-containing alkyl succinic diester of the present invention have a low coefficient of friction and a more stable running under a low temperature environment. And at the same time,
It is clear that CSS has excellent durability. On the other hand, it is apparent that the friction coefficient of a magnetic disk provided with a lubricant layer comprising only a conventional lubricant increases, and that the durability of CSS is inferior.

In the examples, (Formula 7), (Formula 13), and (Formula 7)
And a mixture of a conventionally known lubricant and (Chemical Formula 7) a rust preventive agent have been described, but (Chemical Formula 14), (Chemical Formula 17), (Chemical Formula 18),
Similar effects can be obtained with the substances of the formulas (24), (25), (26), and (27), and mixtures of these substances with conventionally known lubricants and rust inhibitors.

In the examples, phosphite has been described as a rust preventive. However, hydrogen phosphite, trithiophosphite, phosphate, thiophosphate, dithiophosphate, trithiophosphate, tetrathiophosphate, phosphonate, and phosphoric amide are similarly used. The effect of is obtained.

[0084]

As described above, the magnetic recording medium of the present invention has a ferromagnetic metal thin film provided on a non-magnetic support,
A lubricant layer containing at least one fluorine-containing alkyl succinic diester of the present invention is provided on the ferromagnetic metal thin film via a protective film.

The fluorinated alkyl succinic diester has a fluoroalkyl terminal group having one fluoroalkylene oxide chain in the same molecule and two aliphatic hydrocarbon terminal groups, that is, an aliphatic alkyl terminal group or an aliphatic alkenyl group. It is a structure having a terminal group.

The fluoroalkyl terminal group is exposed on the surface of the metal thin film, the surface of the protective film, or the surface of the magnetic head to contribute to lowering the energy of the surface, and forms a non-adhesive surface. Further, the fluoroalkylene oxide chain in the fluorine-containing alkyl succinic diester molecule exerts a protective effect on the surface of the metal thin film and the surface of the magnetic head. further,
Fluoroalkylene oxide chains exhibit good lubricity because they have the effect of softening the rigid fluorine-containing hydrocarbon end chains due to the presence of the ether linking group, and achieve both non-adhesiveness and lubricity.

In addition, the aliphatic hydrocarbon terminal group has good lubricity because it is a flexible carbon-carbon bond chain. And, due to the synergistic effect of each of these terminal groups, the magnetic recording medium provided with the lubricant layer containing the fluorine-containing alkyl succinic diester of the present invention has an excellent effect that lubricity does not decrease in a low temperature environment. Can be

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of infrared spectroscopic analysis of the fluorine-containing alkyl succinic diester shown in Example 1.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Sachiko Aiuchi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Mikio Murai 1006 Okadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Inside

Claims (4)

[Claims] 1. A fluorine-containing alkyl succinic diester 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 group, R ₃ represents —O— or —S—, and R ₄ represents —S— or —SC ₂ H. ₄ S-, m is an integer of 1 to 6, n is an integer of 1 to 30, R ₅ is an aliphatic alkyl group or an aliphatic alkenyl group, and R ₆ is -O- or -S A is 0 or 1 and b is 0 or 1. 2. The fluorine-containing alkyl according to claim 1, wherein a fluoroalkylene oxide-containing fluoroalkyl alcohol or a fluoroalkylene oxide-containing fluoroalkylthiol represented by the following general formula is used as a starting material. Succinic diester. Embedded image Here, R ₂ represents a fluoroalkyl group, and R ₃ represents —O— or
Represents -S-, m is an integer of 1 to 6, and n is 1 to 30
Is an integer. 3. A lubricating material comprising a ferromagnetic metal film provided on a non-magnetic support, and one or more of the fluorine-containing alkyl succinic diesters according to claim 1 interposed therebetween through a protective film. A magnetic recording medium characterized by comprising an agent layer. 4. The magnetic recording medium according to claim 3, wherein the protective film is made of diamond-like carbon.