JPH1180073A - Magnetic recording medium provided with a fluorinated alkyl carboxylic acid and a lubricant layer containing the fluorinated alkyl carboxylic acid - Google Patents

Abstract

(57) [Problem] To provide a substance whose lubricity does not decrease in a high temperature environment. SOLUTION: The fluorinated alkyl carboxylic acid represented by the following chemical formula having an absorption peak of 1,700 cm- ¹ of carboxylic acid. Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl group or a perfluoropolyether group, R ₃ represents —O— or —S—, and a
Is an integer of 0 to 20, and b is 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a precision machine, a lubricant for a precision part, a surfactant,
The present invention relates to a magnetic recording medium provided with a fluorine-containing compound useful as a release agent and a rust preventive, and a lubricant layer containing the fluorine-containing compound.

[0002]

2. Description of the Related Art With the miniaturization and high precision of mechanical devices and parts, the lubrication mode of these sliding parts 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 provides high-precision lubrication for sliding between a magnetic tape or a magnetic disk and a magnetic head. It has become necessary.

[0003] For example, in the case of a vapor-deposited tape or a hard disk, the surface loss of a magnetic layer must be minimized in order to increase the output while minimizing the spacing loss between the magnetic recording medium and the magnetic head while ensuring durability and reliability. Is formed to have a thickness of only several tens of millimeters.

[0004] Therefore, development of an organic compound having excellent lubricity as a material for forming the lubricant layer has become an important issue.

Conventionally, as a lubricant for a metal thin-film type magnetic recording medium, there is a fluorine-containing alkyl carboxylic acid monoester represented by the following formula (Formula 14) (Japanese Patent Application No. 8-7600).
issue).

[0006]

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[0007]

However, the formula (Formula 1)
The fluorine-containing alkyl carboxylic acid monoester lubricant described in 4) has a problem that lubricity is reduced in a high temperature environment.

The present invention has been made in order to solve such a conventional problem, and has excellent running performance, durability, and weather resistance, and can maintain practical reliability under high temperature environment conditions. It is intended to provide a recording medium.

[0009]

According to the magnetic recording medium of the present invention, a ferromagnetic metal film is provided on a nonmagnetic support, and a fluorine-containing alkylcarboxylic acid is coated on the ferromagnetic metal film via a protective film. It is characterized in that a lubricant layer to be contained is provided.

The fluorinated alkyl carboxylic acid used in the present invention is represented by the following general formula (Formula 15), and one fluorinated terminal group, ie, a fluoroalkyl group or a perfluoropolyether terminal group, in the same molecule. It has a group, one aliphatic hydrocarbon terminal group, that is, an aliphatic alkyl terminal group or an aliphatic alkenyl terminal group, and a carboxyl group.

[0011]

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However, R ₁ is an aliphatic alkyl group or an aliphatic alkenyl group, and has 6 to 30 carbon atoms, preferably 10 to 30 carbon atoms.
~ 24 is suitable, when the carbon number is less than 6 or more than 30,
Lubricity decreases. R ₂ is a fluoroalkyl group or a perfluoropolyether group. If it is a fluoroalkyl group, it preferably has 1 to 12 carbon atoms. If it is a perfluoropolyether group, the following formula (Formula 16) (Formula 17), (Formula 1
8) is suitable, the molecular weight of the perfluoropolyether group is about 200 to 6,000, preferably 300 to 4,000, and the molecular weight is out of the range. , Lubricity and storage reliability decrease. R ₃
Is -O- or -S-, a is an integer of 0 to 20, preferably 0 to 10, and b is 0 or 1.

[0013]

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[0014]

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[0015]

Embedded image R ₄ (OC _m F _2m ) _n O (CF ₂ ) _m-1 — wherein R ₄ represents a fluoroalkyl group having 1 to 30, preferably 1 to 8 carbon atoms, and m represents 1 to It is an integer of 6, and n is an integer of 1 to 30, preferably 1 to 8, and if it is out of these ranges, lubricity and storage reliability will be reduced.

This lubricant layer is formed by adding a fluorinated alkyl carboxylic acid represented by the general formula (Formula 15) or a fluorinated alkyl carboxylic acid and another lubricant, a rust preventive, an extreme pressure agent 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 content of the fluorinated alkyl carboxylic acid is less than 40 mol%, it is difficult to obtain the effects of the present invention. Moreover, its abundance, the surface 1 m ² per 0.05 to 100 mg, preferably 0.1~50mg
The range is suitable. Further, as the above-mentioned other lubricants and rust preventives, the following formulas (Formula 19), (Formula 20), (Formula 21), (Formula 22),
The use of the organic phosphorus compound represented by any one of the formulas (Chemical Formula 23), (Chemical Formula 24), (Chemical Formula 25), (Chemical Formula 26), and (Chemical Formula 27) further improves the lubricating performance and improves the durability of the recording medium Is improved.

[0017]

Embedded image HP (O) (OC _n H _{2n + 1} ) ₂

[0018]

Embedded image P (OC _n H _{2n + 1} ) ₃

[0019]

_{Embedded image} P (SC _n H _{2n + 1} ) ₃

[0020]

Embedded image O = P (OC _n H _{2n + 1} ) ₃

[0021]

Embedded image S = P (OC _n H _{2n + 1} ) ₃

[0022]

Embedded image O = P (SC _n H _{2n + 1} ) ₃

[0023]

Embedded image S = P (SC _n H _{2n + 1} ) ₃

[0024]

_{Embedded image} (C _n H _{2n + 1} O) ₂ P (O) OH

[0025]

Embedded image is preferably a carbon number n of _{(C n H 2n + 1 O} ) P (O) (OH) 2 The organophosphorus compound is 8 to 20, the carbon number n is 21 or more, When the solubility in a general-purpose solvent decreases and the number of carbon atoms n is 7 or less, the lubricity of the recording medium decreases. The addition amount is suitably in the range of 0 to 60%, preferably 0 to 40%. If the content of the fluorinated alkyl carboxylic acid is less than 40%, it is difficult to obtain the effects of the present invention.

The protective film is formed by sputtering or plasma CV.
D or the like, a carbon thin film in an amorphous state, a graphite state, a diamond state, or a mixed state or a laminated state of them can be applied, and the thickness thereof is preferably 50 to 500 °.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine-containing alkylcarboxylic acid used in the present invention is represented by the following general formula (Formula 28):
One fluorinated terminal group, i.e., a fluoroalkyl group or a perfluoropolyether terminal group, and one aliphatic hydrocarbon terminal group, i.e., an aliphatic alkyl terminal group or an aliphatic alkenyl terminal group; And a structure having a group.

[0028]

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Here, R ₁ is an aliphatic alkyl group or an aliphatic alkenyl group and has 6 to 30 carbon atoms, preferably 10 to 30 carbon atoms.
~ 24 is suitable, when the carbon number is less than 6 or more than 30,
Lubricity decreases. R ₂ is a fluoroalkyl group or a perfluoropolyether group. If it is a fluoroalkyl group, it preferably has 1 to 12 carbon atoms. If it is a perfluoropolyether group, the following formula (Formula 29) (Formula 30), (Formula 3
The structure represented by any of 1) is suitable, and the molecular weight of the perfluoropolyether group is about 200 to 6,000, preferably 300 to 4,000, and if the molecular weight is out of these ranges, lubrication occurs. And storage reliability are reduced. R ₃
Is -O- or -S-, a is an integer of 0 to 20, preferably 0 to 10, and b is 0 or 1.

[0030]

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[0031]

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[0032]

Embedded image R ₄ (OC _m F _2m ) _n O (CF ₂ ) _{m-1 wherein} R ₄ represents a fluoroalkyl group having 1 to 30, preferably 1 to 8 carbon atoms, and m represents 1 to It is an integer of 6, and n is an integer of 1 to 30, preferably 1 to 8, and if it is out of these ranges, lubricity and storage reliability will be reduced.

In the first method for producing a fluorinated alkyl carboxylic acid used in the present invention, a fluorinated alkyl carboxylic acid ester is synthesized by mixing and stirring an α-mercapto carboxylic acid alkyl ester and a fluorinated alkyl halide, The fluorinated alkyl carboxylic acid ester is subjected to ester hydrolysis in a basic catalyst to obtain a fluorinated alkyl carboxylic acid.

The reaction between the α-mercaptocarboxylic acid alkyl ester and the fluorinated alkyl halide proceeds conveniently when heated and stirred in the presence of methyl ethyl ketone and methyl isobutyl ketone as solvents. Heating temperature is 60
When the temperature is lower than this range at 100 to 100 ° C., preferably 70 to 90 ° C., unreacted substances tend to remain, and when the temperature is higher, by-products tend to be formed.

Examples of the usable α-mercaptocarboxylic acid alkyl ester include α-mercaptododecyl acid alkyl ester, α-mercaptotridecyl acid alkyl ester, α-mercaptotetradecyl acid alkyl ester, α-mercaptopentadecyl acid alkyl ester,
α-mercaptohexadecyl acid alkyl ester, α-
Alkyl mercaptoheptadecylate, α-mercaptooctadecylate, α-mercaptononadesylate, α-mercaptoicosanilate, α-mercaptohenicosanilate, α-mercaptodocosanyl There are acid alkyl esters.

Further, as the fluorine-containing alkyl halide,
Perfluoropentyl alkyl bromide, perfluorohexyl alkyl bromide, perfluoroheptyl alkyl bromide, perfluorooctyl alkyl bromide, perfluorononyl alkyl bromide, perfluorodecyl alkyl bromide, perfluoroundecyl alkyl bromide, perfluorododecyl alkyl bromide, per Fluoropolyether bromide, perfluoropentyl alkyl iodide, perfluorohexyl alkyl iodide, perfluoroheptyl alkyl iodide, perfluorooctyl alkyl iodide, perfluorononyl alkyl iodide, perfluorodecyl alkyl iodide, perfluoroun Decylalkyl iodide, perfluorododecyl Le Killua iodide, there perfluoropolyether iodide.

The molar ratio between the α-mercaptocarboxylic acid alkyl ester and the fluorine-containing alkyl halide is equimolar, and the reaction proceeds conveniently when the α-mercaptocarboxylic acid alkyl ester and equimolar anhydrous potassium carbonate are added.

In order to isolate the target compound from the thus obtained mixture, the solvent is removed by distillation under reduced pressure, and the residue is extracted with an organic solvent to obtain a compound-containing alkylcarboxylic acid. This compound was found to be a fluorinated alkylcarboxylic acid by infrared spectroscopy (I
R), gel permeation chromatography (GPC)
And organic mass spectrometry (FD-MS).

In the second method for producing a fluorinated alkyl carboxylic acid used in the present invention, an α-halo-carboxylic acid alkyl ester and a fluorinated alkyl alcoholate are mixed and stirred to form a fluorinated alkyl carboxylic acid ester. After the synthesis, this fluorine-containing alkylcarboxylic acid ester is subjected to ester hydrolysis in a basic catalyst to obtain a fluorine-containing alkylcarboxylic acid.

The reaction between the α-halo-carboxylic acid alkyl ester and the fluorinated alkyl alcoholate proceeds conveniently when heated and stirred in the presence of methyl ethyl ketone and methyl isobutyl ketone as solvents. Heating temperature is 60
When the temperature is lower than this range at 100 to 100 ° C., preferably 70 to 90 ° C., unreacted substances tend to remain, and when the temperature is higher, by-products tend to be formed.

Examples of the usable α-halo-carboxylic acid alkyl ester include α-bromo-dodecyl acid alkyl ester, α-bromo-tridecyl acid alkyl ester,
α-bromo-tetradecyl acid alkyl ester, α-bromo-pentadecyl acid alkyl ester, α-bromo-
Hexadecyl acid alkyl ester, α-bromo-heptadecyl acid alkyl ester, α-bromo-mercaptooctadecyl acid alkyl ester, α-bromo-mercaptononadecylic acid alkyl ester, α-bromo-mercaptoicosanilic acid alkyl ester, α-bromo -Alkyl mercaptohenicosanilic acid, alkyl α-iodo-mercaptodocosanilic acid, alkyl α-iodo-dodecyl acid, alkyl α-iodo-tridecylate, alkyl α-iodo-tetradecylate, α- Alkyl iodo-pentadecylate, α-iodo-hexadecylate, α-iodo-heptadecylate,
α-Iodo-mercaptooctadecyl acid alkyl ester, α-iodo-mercaptononadecyl acid alkyl ester, α-iodo-mercaptoicoicanilic acid alkyl ester, α-iodo-mercaptohenicosanilic acid alkyl ester, α-iodo- There are alkyl mercaptodocosanilates.

Examples of the fluorinated alkyl alcoholate include perfluoropentyl alkyl alcoholate, perfluorohexyl alkyl alcoholate, perfluoroheptyl alkyl alcoholate, perfluorooctyl alkyl alcoholate, perfluorononyl alkyl alcoholate, perfluorodecyl alkyl alcoholate, and perfluoroalkyl alcoholate. There are undecyl alkyl alcoholates, perfluorododecyl alkyl alcoholates, and perfluoropolyether alcoholates.

The molar ratio between the α-halo-carboxylic acid alkyl ester and the fluorinated alkyl alcoholate is equimolar.

In order to isolate the target compound from the thus obtained mixture, the solvent is removed by distillation under reduced pressure, and the residue is extracted with an organic solvent to obtain a compound-containing alkylcarboxylic acid. This compound can be identified as a fluorinated alkyl carboxylic acid by IR, GPC and FD-MS.

In a third method for producing a fluorinated alkyl carboxylic acid used in the present invention, a fluorinated alkyl halide is reacted with magnesium to form a fluorinated alkyl magnesium halide, which is converted to an α-halo-carboxylic acid. In this method, a fluorine-containing alkylcarboxylic acid ester is synthesized by mixing and stirring with an alkyl ester, and then the fluorine-containing alkylcarboxylic acid ester is subjected to ester hydrolysis in a basic catalyst to obtain a fluorine-containing alkylcarboxylic acid.

The reaction between the α-halo-carboxylic acid alkyl ester and the fluorine-containing alkylmagnesium halide proceeds conveniently when heated and stirred in the presence of anhydrous diethyl ether and anhydrous diisopropyl ether as solvents. The heating temperature is 20 to 70 ° C., preferably 30 to 50 ° C. If the temperature is lower than this range, unreacted substances tend to remain, and if the temperature is high, by-products tend to be formed.

Examples of the usable α-halo-carboxylic acid alkyl ester include α-bromo-dodecyl acid alkyl ester, α-bromo-tridecyl acid alkyl ester,
α-bromo-tetradecyl acid alkyl ester, α-bromo-pentadecyl acid alkyl ester, α-bromo-
Hexadecyl acid alkyl ester, α-bromo-heptadecyl acid alkyl ester, α-bromo-mercaptooctadecyl acid alkyl ester, α-bromo-mercaptononadecylic acid alkyl ester, α-bromo-mercaptoicosanilic acid alkyl ester, α-bromo -Alkyl mercaptohenicosanilic acid, alkyl α-iodo-mercaptodocosanilic acid, alkyl α-iodo-dodecyl acid, alkyl α-iodo-tridecylate, alkyl α-iodo-tetradecylate, α- Alkyl iodo-pentadecylate, α-iodo-hexadecylate, α-iodo-heptadecylate,
α-Iodo-mercaptooctadecyl acid alkyl ester, α-iodo-mercaptononadecyl acid alkyl ester, α-iodo-mercaptoicoicanilic acid alkyl ester, α-iodo-mercaptohenicosanilic acid alkyl ester, α-iodo- There are alkyl mercaptodocosanilates.

Examples of the fluorinated alkyl magnesium halide include perfluoropentyl alkyl magnesium halide, perfluorohexyl alkyl magnesium halide, perfluoroheptyl alkyl magnesium halide, perfluorooctyl alkyl magnesium halide, perfluorononyl alkyl magnesium halide, and perfluoroalkylmagnesium halide. There are decyl alkyl magnesium halide, perfluoroundecyl alkyl magnesium halide, perfluorododecyl alkyl magnesium halide, and perfluoropolyether magnesium halide.

The molar ratio between the α-halo-carboxylic acid alkyl ester and the fluorine-containing alkyl magnesium halide is equimolar. In order to isolate the target compound from the thus obtained mixture, the solvent is removed by distillation under reduced pressure, and the residue is extracted with an organic solvent to obtain a fluorine-containing alkylcarboxylic acid compound. This compound may be a fluorine-containing alkyl carboxylic acid,
And FD-MS.

[0050]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be specifically described. The substance of this example is represented by the following formula (Formula 32).

[0051]

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The substance represented by the formula (Formula 32) is converted into a compound represented by the formula (Formula 2)
Explaining in comparison with 8), R ₁ is a hexadecyl group having 16 carbon atoms, R ₂ is a fluoroalkyl group having 7 carbon atoms bonded to fluorine, R ₃ is -S-, a is 1 and b is 1. It is.

Next, a method for producing the substance represented by the formula (Formula 32) will be described.

The starting material is α represented by the following formula (Formula 33).
34.4 g (0.10 mol) of ethyl mercaptostearate and 51.0 g (0.10 mol) of perfluoroheptylmethyl iodide represented by the following formula (Formula 34).

[0055]

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[0056]

Embedded image C ₇ F ₁₅ CH ₂ I A raw material represented by the formula (Formula 33) and the formula (Formula 34), 9.9 g (0.10 mol) of anhydrous potassium carbonate, and 500 ml of methyl ethyl ketone were added to a reactor equipped with a stirring blade. To a liter flask,
The reaction was performed at 70 ° C. for 24 hours. After the completion of the reaction, methyl ethyl ketone and potassium hydrogen carbonate were removed, and the reaction mixture was dissolved in hexane.
-The ethyl mercaptostearate was removed.

Further, the same treatment was carried out using the reaction mixture as a methanol solution to remove unreacted perfluoroheptylmethyl iodide and perfluoroheptylmethyl derivative to obtain 72.6 g of a transparent liquid. It was found by IR, GPC and FD-MS that the transparent liquid was a substance represented by the following formula (Chemical formula 35) which did not contain starting materials and by-products.

[0058]

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The substance represented by the formula (Formula 35) was collected in a 1-liter flask equipped with a stirring blade, and a 90 vol.% Ethanol solution (40% distilled water containing 40 g of caustic soda) was dissolved therein.
vol.%) and reflux for 18 hours. And
The solution is cooled and 300 ml of 4N hydrochloric acid is added while stirring.
, And the solution is stirred at 70 ° C. for 2 hours.
The reaction product was filtered under reduced pressure, dissolved in 500 ml of ethyl acetate, and the solution was washed repeatedly with distilled water until the pH became 7, and dried over anhydrous sodium sulfate.

Next, the ethyl acetate was distilled off, and the reaction product was recrystallized at 0 ° C. as an ethanol solution to obtain 69.8 g of a white semi-solid. This white semi-solid is a substance represented by the formula (Formula 32) containing no starting materials and by-products.
R, GPC and FD-MS revealed. FIG. 1 shows an IR spectrum of this compound by IR.

IR: disappearance of absorption peak of ester at 1,735 cm- ¹ and absorption peak of alcohol at 3,330 cm- ¹ and appearance of absorption peak of carboxylic acid at 1,700 cm- ¹ . GPC: appearance of fluorinated alkyl carboxylic acid. α-mercaptostearic acid ethyl ester, perfluoroheptylmethyl iodide Not detected. FD-MS: main peak at m / e 698.

In this example, R ₁ in the general formula (Chemical Formula 28) is a hexadecyl group having 16 carbon atoms, R ₂ is a fluoroalkyl group having 7 carbon atoms bonded to fluorine, and R ₃ is -S-, a Is 1,
Although the production method in the case where b is 1 has been described, even in the case where the production method is different from this, the starting material is an α-mercaptocarboxylic acid alkyl ester, for example, the following formula (Formula 3)
By using the starting material represented by the formula (6) or the formula (Formula 37), the substance represented by the following formula (Formula 38) or the formula (Formula 39) can be similarly produced.

Further, by using a substance represented by the following formula (Formula 40) or Formula (Formula 41) as a starting material as a fluorine-containing alkyl halide, similarly, the following formula (Formula 42) or Formula (Formula 42) The substance represented by Chemical formula 43) can be produced.

[0064]

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[0065]

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[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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[0071]

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(Embodiment 2) Hereinafter, a second embodiment of the present invention will be specifically described. The substance of this example is represented by the following formula (Formula 44).

[0073]

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The substance represented by the formula (Formula 44) is represented by the following formula (Formula 2)
Explaining in comparison with 8), R ₁ is a dodecyl group having 12 carbon atoms, R ₂ is a perfluoropolyether group, and R ₃ is —O
-, A is 1 and b is 1.

Next, a method for producing the substance represented by the formula (Formula 44) will be described.

The starting material is α represented by the following formula (Formula 45).
33.5 g (0.10 mol) of ethyl bromo-myristate and 105.2 g (0.10 mol) of sodium perfluoropolyether methoxide represented by the following formula (Formula 46).

[0077]

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[0078]

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A raw material represented by the formula (Formula 45) and the formula (Formula 46),
500 ml of methyl ethyl ketone was collected in a 1-liter flask equipped with a stirring blade, and reacted at 70 ° C. for 24 hours. After completion of the reaction, methyl ethyl ketone was distilled off, and the reaction mixture was dissolved in hexane and cooled to -10 ° C to remove unreacted α-bromo-myristate ethyl ester.

Further, the same treatment was performed using the reaction mixture as a methanol solution, and unreacted perfluoropolyether sodium methoxide and perfluoropolyether derivative were removed to obtain 128.4 g of a transparent liquid. This transparent liquid was a substance represented by the following formula (Chemical Formula 47) containing no starting materials and by-products, and was determined by IR, GPC and FD-M.
Found by S.

[0081]

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The substance represented by the formula (Formula 47) was collected in a 1-liter flask equipped with a stirring blade, and 40 g of caustic soda was dissolved in a 90 vol.% Ethanol solution (distilled water 1).
500 ml (containing 0 vol.%) And reflux for 18 hours. Then, the solution is cooled, and 4N hydrochloric acid 30
After slowly adding 0 ml, the solution was stirred at 70 ° C. for 2 hours, the reaction product was filtered under reduced pressure, dissolved in 500 ml of ethyl acetate, and the solution was washed repeatedly with distilled water until the pH became 7. , And dried over anhydrous sodium sulfate.

Next, ethyl acetate was distilled off, and the reaction product was recrystallized at 0 ° C. as an ethanol solution to obtain 125.6 g of a white semi-solid. This white solid is a substance represented by the formula (Formula 44) containing no starting materials and by-products.
R, GPC and FD-MS revealed.

IR: disappearance of absorption peak of ester at 1,735 cm- ¹ and appearance of absorption peak of carboxylic acid at 1,700 cm- ¹ . GPC: appearance of fluorinated alkyl carboxylic acid. α-Bromo-myristic acid ethyl ester, perfluoropolyether sodium methoxide Not detected. FD-MS: Main peak at m / e 1,256.

In this example, R ₁ in the general formula (Formula 15) is a dodecyl group having 12 carbon atoms, R ₂ is a perfluoropolyether group, R ₃ is —O—, a is 1 and b is 1 Although the production method in the case of was described, even in the case of a different case, the starting material is, for example, an α-halo-carboxylic acid alkyl ester, and By using the same, a substance represented by the following formula (Formula 50) or Formula (Formula 51) can be similarly produced.

Further, by using a substance represented by the following formula (Formula 52) or (Formula 53) as a starting material, for example, as a fluorine-containing alkyl alcoholate, the following formula (Formula 54)
Alternatively, a substance represented by the formula (Formula 55) can be produced.

[0087]

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[0088]

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[0089]

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[0090]

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[0091]

Embedded image C ₁₀ F ₂₁ C ₂ H ₄ ONa

[0092]

Embedded image C ₆ F ₁₃ C ₄ H ₈ ONa

[0093]

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[0094]

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(Embodiment 3) Hereinafter, a third embodiment of the present invention will be specifically described. The substance of this example is represented by the following chemical formula (Formula 56).

[0096]

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The substance represented by the formula (Formula 56) is converted to a compound represented by the formula (Formula 2)
Explaining in comparison with 8), R ₁ is a hexadecyl group having 16 carbon atoms, R ₂ is a fluoroalkyl group having 7 carbon atoms bonded to fluorine, a is 4 and b is 0.

Next, a method for producing the substance represented by the formula (Formula 56) will be described.

The starting material is α represented by the following formula (Formula 57)
-Bromostearic acid ethyl ester 39.1 g (0.10 mol)
And 52.9 g (0.10 mol) of perfluoroheptylbutylmagnesium bromide represented by the following formula (Formula 58).

[0100]

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[0101]

C ₇ F ₁₅ (CH ₂ ) ₄ MgBr The raw materials represented by the formulas (Formula 57) and (Formula 58) and 500 ml of anhydrous diethyl ether are collected in a 1-liter flask equipped with a stirring blade. And reacted at 40 ° C. for 24 hours. After completion of the reaction, diethyl ether methyl was removed, the reaction mixture was dissolved in hexane, and cooled to −10 ° C. to remove unreacted α.
-Bromo-stearic acid ethyl ester was removed.

Further, the same treatment was performed using the reaction mixture as a methanol solution to remove unreacted perfluoroheptylbutylmagnesium bromide.
I got This transparent liquid is a substance represented by the following formula (Formula 59) containing no starting materials and by-products.
GPC and FD-MS revealed.

[0103]

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The substance represented by the formula (Chemical Formula 59) was collected in a 1-liter flask equipped with a stirring blade, and 40 g of caustic soda was dissolved in a 90 vol.% Ethanol solution (distilled water 1).
500 ml (containing 0 vol.%) And reflux for 18 hours. Then, the solution is cooled, and 4N hydrochloric acid 30
After slowly adding 0 ml, the solution was stirred at 70 ° C. for 2 hours, the reaction product was filtered under reduced pressure, dissolved in 500 ml of ethyl acetate, and the solution was washed repeatedly with distilled water until the pH became 7. , And dried over anhydrous sodium sulfate.

Next, ethyl acetate was distilled off, and the reaction product was recrystallized at 0 ° C. as an ethanol solution to obtain 70.8 g of a white semi-solid. This white solid was found to be a substance of the formula (Formula 56) containing no starting materials and by-products.
R, GPC and FD-MS revealed.

[0106] IR: absorption peak disappearance of 1,735cm ~ ¹ of the ester, absorption peak appearance of 1,700cm ~ ¹ of a carboxylic acid. GPC: appearance of fluorinated alkyl carboxylic acid. α-Bromo-stearic acid ethyl ester, perfluoroheptylbutylmagnesium bromide Not detected. FD-MS: Main peak at m / e 708.

In this example, R ₁ in the general formula (Chemical Formula 15) is a hexadecyl group having 16 carbon atoms, R ₂ is a fluoroalkyl group having 7 carbon atoms bonded to fluorine, a is 4 and b is 0. Although the production method in a certain case has been described, even in a case different from this, a starting material is used as an α-halo-carboxylic acid alkyl ester, for example, using a material represented by the following formula (Chemical Formula 60) or Formula (Chemical Formula 61). Thus, similarly, the following equation
The compound represented by the formula (Formula 62) or the formula (Formula 63) can be produced.

The starting material is a fluorinated alkylmagnesium halide, for example, represented by the following formula (Chem. 64) or (Chem. 6)
Similarly, by using the substance represented by 5), a substance represented by the following formula (Formula 66) or Formula (Formula 67) can be produced.

[0109]

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[0110]

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[0111]

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[0112]

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[0113]

Embedded image C ₃ F ₇ O (C ₂ F ₄ O) ₃ CF ₂ CH ₂ MgBr

[0114]

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[0115]

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[0116]

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(Embodiment 4) Next, an embodiment of the magnetic recording medium of the present invention will be specifically described. In addition, the present invention
It is not limited to these embodiments.

The non-magnetic support in the magnetic recording medium of this embodiment has a gentle gradient of 70 ° and a diameter of 1 μm due to silica fine particles added into the polyester film.
There are several granular projections per 100 μm ^{2 on the} surface, and a relatively large projection due to fine particles due to the polymerization catalyst residue has been reduced to a minimum on the polyester film surface.
Steep mountain-like projections with 0 mm silica colloid particles as nuclei and UV-curable epoxy resin as binder are 1 × 1 per 1 mm ²
Those formed such that 0 ⁷ was used. Then, on the non-magnetic support, a continuous vacuum oblique vapor deposition method is used.
A Co—Ni ferromagnetic film having an i content of 20% and a thickness of 1,000 Å was provided in the presence of a trace 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 mm by the method D, a fluorine-containing alkyl carboxylic acid represented by the formula (Formula 32) is applied on the protective film so as to have an amount of 10 mg per 1 m ^2. Then, after forming a lubricant layer, it is cut into a predetermined width to produce a magnetic tape.

The magnetic tape was mounted on a commercially available VCR at 40 ° C. and 80% RH, and the output characteristics during repeated running were measured. The RF output was reduced by 3 dB from the initial value. Or the number of runs before the output fluctuation occurred.

(Example 5) In the magnetic tape of the fourth example, instead of the substance represented by the formula (Formula 32), the formula (Formula 44) was used.
A magnetic tape was produced using the substance indicated by the above formula, and the same test was conducted.

(Example 6) In the magnetic tape of the fourth example, instead of the substance represented by the formula (Formula 32), the formula (Formula 32)
And a conventionally known lubricant C ₁₇ H ₃₃ COOC ₂
A similar test was conducted by producing a magnetic tape using a substance in which H ₄ C ₈ F ₁₇ was mixed at a weight ratio of 1: 1.

(Example 7) In the magnetic tape of the fourth example, instead of the substance represented by the formula (Formula 32), the formula (Formula 32) was used.
A magnetic tape was prepared using a substance obtained by mixing a substance represented by the following formula and a rust inhibitor (C ₁₂ H ₂₅ S) ₃ P at a weight ratio of 2: 1, and the same test was performed.

The test results according to the above examples are shown in the following (Table 1). The lubricant of Conventional Example 1 in (Table 1) is represented by the formula
It is a fluorine-containing alkyl carboxylic acid monoester represented by the following formula (14).

[0125]

[Table 1]

From Table 1, it is clear that all the magnetic tape samples provided with the lubricant layer containing the fluorinated alkylcarboxylic acid of the present invention have excellent lubricity in a high temperature environment.

On the other hand, it is apparent that the lubricating property of the conventional magnetic tape provided with the lubricant layer consisting of only the lubricant is reduced in a high temperature environment.

In the examples, the material represented by the formula (Formula 32), the material represented by the formula (Formula 44), the material represented by the formula (Formula 32) and a conventionally known lubricant or rust inhibitor are used. The mixture with was described, but the formulas (38), (39), (50),
(Formula 51), Formula (Formula 56), Formula (Formula 62), Formula (Formula 63), Formula (Formula 66), Formula
The same effect can be obtained with a mixture of each of the substances shown in (Chemical formula 67) and these substances and a conventionally known lubricant or rust inhibitor.

(Embodiment 8) Next, an embodiment of another magnetic recording medium of the present invention will be specifically described. Note that the present invention is not limited to these examples.

The non-magnetic support in the magnetic recording medium of this embodiment has a thickness of 95 mm and a thickness of 1.2 mm on an Al alloy plate.
A projection was formed by applying a non-magnetic Ni-P alloy plating of 25 μm and forming a projection having an average roughness of 50 ° and a maximum height of 300 ° by texturing. Then, on the nonmagnetic Ni-P alloy plating, a thickness of 1,300 mm is formed by a sputtering method.
The sample A was formed by forming a Cr underlayer and a 600 ° -thick Co—Ni ferromagnetic film, and forming a 200 ° -thick graphite protective film on the ferromagnetic film by sputtering. I do.

A sample B was prepared by forming a 50-mm-thick diamond-like carbon protective film by a plasma CVD method in place of the graphite protective film.

Next, on the protective films of samples A and B,
A magnetic disk was prepared by applying a fluorine-containing alkylcarboxylic acid represented by the following formula (Formula 32) in an amount of 10 mg per 1 m ² and providing a lubricant layer.

The magnetic disk was subjected to a CSS (contact start / stop) test in an environment of 40 ° C. and 80% RH, and the number of CSSs when the friction coefficient exceeded 1.0 or the CSS at the time of head crash occurred The durability was determined by the number of times.

(Embodiment 9) In the magnetic disk of the eighth embodiment, instead of the substance represented by the formula (Formula 32), the formula (Formula 4)
A magnetic disk using the substance shown in 4) was manufactured, and a similar test was performed.

(Embodiment 10) In the magnetic disk of the eighth embodiment, instead of the substance represented by the formula (Formula 32), a material represented by the formula (Formula 32) is used in the same manner as in the sixth embodiment. A magnetic disk using a substance obtained by mixing a conventionally known lubricant C ₁₇ H ₃₃ —COOC ₂ H ₄ C ₈ F ₁₇ at a weight ratio of 1: 1 was manufactured, and the same test was performed.

(Embodiment 11) In the magnetic disk of the eighth embodiment, instead of the substance represented by the formula (Formula 32), a material represented by the formula (Formula 32) is used in the same manner as in the seventh embodiment. Rust inhibitor (C
A magnetic disk using a substance in which ₁₂ H ₂₅ S) ₃ P was mixed at a weight ratio of 2: 1 was prepared, and a similar test was performed.

The test results of the above examples are shown in the following (Table 2). The lubricant of Conventional Example 2 in (Table 2) is represented by the formula
It is a fluorine-containing alkyl carboxylic acid monoester represented by the following formula (14).

[0138]

[Table 2]

From Table 2, it can be seen that all magnetic disks provided with a lubricant layer containing at least one kind of fluorine-containing alkylcarboxylic acid of the present invention have excellent CSS durability under a high temperature environment. It is clear.

On the other hand, it is apparent that a conventional magnetic disk provided with a lubricant layer consisting of only a lubricant has poor CSS durability in a high temperature environment.

In the examples, the material represented by the formula (Formula 32), the material represented by the formula (Formula 44), the material represented by the formula (Formula 32), and a conventionally known lubricant or rust inhibitor are used. The mixture with was described, but the formulas (38), (39), (50),
(Formula 51), Formula (Formula 56), Formula (Formula 62), Formula (Formula 63), Formula (Formula 66), Formula
The same effect can be obtained also with a mixture of the substances represented by the chemical formulas (67) and these substances and a conventionally known lubricant or rust inhibitor.

[0142]

As is apparent from the above description, the magnetic recording medium of the present invention includes a ferromagnetic metal thin film provided on a nonmagnetic support, and a ferromagnetic metal thin film provided on the ferromagnetic metal thin film via a protective film. A lubricant layer containing at least one kind of a fluorine-containing alkylcarboxylic acid is provided.
One fluorinated terminal group, i.e., a fluoroalkyl group or a perfluoropolyether terminal group, and one aliphatic hydrocarbon terminal group, i.e., an aliphatic alkyl terminal group or an aliphatic alkenyl terminal group; And a structure having a group.

The fluorine-containing 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, and contributes to lowering the energy of those surfaces to form a surface to be adhered.

The aliphatic hydrocarbon end group is a flexible carbon-carbon bond chain, and thus exhibits good lubricity.

Furthermore, the carboxyl 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, since the lubricant of the present invention has no ester bond in the molecule, it has excellent stability even in a high temperature environment.

In addition, due to the synergistic effect of these terminal groups, the magnetic recording medium provided with a lubricant layer containing at least one kind of the fluorinated alkyl carboxylic acid of the present invention does not deteriorate its lubricity in a high temperature environment. An excellent effect is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of infrared spectroscopic analysis of the fluorinated alkylcarboxylic acid shown in Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // (C10M 111/02 105: 54 105: 74) C10N 40:18

Claims (6)

[Claims] 1. A fluorine-containing alkyl carboxylic acid represented by the following general formula (1). Embedded image Here, R ₁ represents an aliphatic alkyl group or an aliphatic alkenyl group, R ₂ represents a fluoroalkyl group or a perfluoropolyether group, R ₃ represents —O— or —S—, and a
Is an integer of 0 to 20, and b is 0 or 1. 2. The perfluoropolyether group of the fluorinated alkylcarboxylic acid has a structure represented by any of the following formulas (2), (3) and (4). Item 4. The fluorine-containing alkyl carboxylic acid according to Item 1. Embedded image Here, k is an integer of 1 or more. Embedded image Here, p and q are integers of 1 or more. Embedded image R ₄ (OC _m F _2m ) _n O (CF ₂ ) _{m-1 wherein} R ₄ represents a fluoroalkyl group, m is an integer of 1 to 6, and n is an integer of 1 to 30 It is. 3. A lubricant comprising: a ferromagnetic metal film provided on a nonmagnetic support; and a lubricant containing at least one kind of the fluorinated alkylcarboxylic acid according to claim 1 via a protective film on the ferromagnetic metal film. A magnetic recording medium comprising a layer. 4. A ferromagnetic metal film is provided on a non-magnetic support, and the fluorine-containing alkylcarboxylic acid according to claim 1 and an organic phosphorus compound are mixed via a protective film on the ferromagnetic metal film. A magnetic recording medium comprising a lubricant layer provided thereon. 5. An organophosphorus compound represented by the following formula:
(Formula 6), (Formula 7), (Formula 8), (Formula 9), (Formula 10), (Formula 11),
5. The magnetic recording medium according to claim 4, wherein the magnetic recording medium is represented by any one of (Chemical Formula 12) and (Chemical Formula 13) and has 8 to 20 carbon atoms. Embedded image HP (O) (OC _n H _{2n + 1} ) ₂ embedded image P (OC _n H _{2n + 1} ) _{3 embedded image} P (SC _n H _{2n + 1} ) ₃ embedded image ＰP (OC _n H _{2n + 1} ) ₃ S = P (OC _n H _{2n + 1} ) ₃ O = P (SC _n H _{2n + 1} ) ₃ S = P _{(SC n H 2n + 1)} 3 embedded image _{(C n H 2n + 1 O} ) 2 P (O) OH embedded image _{(C n H 2n + 1 O} ) P (O) (OH) 2 6. The magnetic recording medium according to claim 3, wherein said protective film is made of diamond-like carbon.