JP2003082089A - Perfluoropolyether-based compound, lubricant comprising the same and recording medium using the lubricant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant for recording media retaining excellent lubricity under various application conditions, maintaining lubricant effect for a long time and having excellent tracking ability, abrasion resistance, durability and the like. SOLUTION: For example, an HOC2H4(CH3)2NHOOC-Rf-COOHN(CH3)2C2H4 OH (Rf expresses a fluoropolyether group having 2,000 average molecular weight) is used as the lubricant for magnetic recording media.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perfluoropolyether compound, a recording medium lubricant comprising the compound, and a recording medium on which a lubricating layer containing the lubricant is formed.

[0002]

2. Description of the Related Art A conventional recording medium, for example, a magnetic recording medium, is a so-called metal thin film type magnetic recording in which a ferromagnetic metal material is deposited on a non-magnetic support by a method such as vapor deposition and the magnetic layer is used as a magnetic layer. In a so-called coating type magnetic recording medium in which a medium or a magnetic coating material containing very fine magnetic particles and a resin binder is coated on a non-magnetic support, and the magnetic layer is used as a magnetic layer, the smoothness of the magnetic layer surface is Since it is extremely good, the substantial contact area with sliding members such as magnetic heads and guide rollers is large, so the friction coefficient is large and the adhesion phenomenon (so-called sticking) tends to occur, resulting in poor running performance and durability. There are many points. Therefore, use of various kinds of lubricants has been studied in order to improve these problems, and higher fatty acids and esters thereof have been conventionally added to the magnetic layer of the magnetic recording medium or top coated. Therefore, attempts have been made to suppress the coefficient of friction.

However, the lubricant used for the magnetic recording medium is required to have very strict characteristics due to its properties.
It is the current situation that it is difficult to deal with the conventional lubricants.

That is, the lubricant used for the magnetic recording medium is (1) excellent in low temperature characteristics so as to ensure a predetermined lubricating effect when used in cold regions, and (2) a lubricant with a magnetic head. As pacing becomes a problem, it is necessary to be able to apply it extremely thinly, to exhibit sufficient lubrication characteristics even in that case, and (3) to endure long-term use or long-term use and to maintain the lubrication effect. To be done.

[0005]

As described above, in the field of magnetic recording media, due to the lack of the ability of the lubricant used, the practical characteristics such as the level reduction of the reproduction output in the shuttle running test are unsatisfactory. Is left. Therefore, the present invention, while maintaining excellent lubricity under various use conditions, the lubricating effect is maintained for a long time, running property,
It is an object of the present invention to provide a magnetic recording medium having excellent wear resistance and durability.

[0006]

That is, the present invention provides the following general formula (1):

[0007]

[Chemical 4]

(In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, and R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. . N represents an integer of 1 to 20.)
The present invention provides a perfluoropolyether compound represented by: The present invention also has the following general formula (1):

[0009]

[Chemical 5]

(In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, and R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. . N represents an integer of 1 to 20.)
The present invention provides a lubricant for a recording medium, which comprises a perfluoropolyether compound represented by Furthermore, the present invention is a recording medium comprising at least a recording layer and a lubricant layer made of a lubricant formed on a support, wherein the lubricant has the following general formula (1):

[0011]

[Chemical 6]

(In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, and R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. . N represents an integer of 1 to 20.)
A recording medium comprising a perfluoropolyether compound represented by

The perfluoropolyether compound of the present invention is a novel substance, and when used as a lubricant for recording media, especially for magnetic recording media, excellent lubricity is maintained under various conditions of use. , Long-lasting lubrication effect, excellent runnability, wear resistance,
It is possible to provide a recording medium having durability and the like.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the case where the compound of the present invention is used as a lubricant for a magnetic recording medium will be described as an example.

In the perfluoropolyether compound of the present invention, R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group, and have a branched structure, an isomer structure, It can be arbitrarily selected regardless of the alicyclic structure, the molecular weight, the presence or absence of an unsaturated bond. However, when it contains a large amount of fluorinated carbon or when the chain length of the hydrocarbon group is short, it is necessary to use a fluorine-based solvent from the viewpoint of the solubility of the lubricant when forming the lubricating film on the magnetic recording medium. There is. Specifically, when R1 and R2 are hydrogen or have a carbon number of 7 or less, there is no problem when using a fluorine-based solvent, but the solubility in an organic solvent such as toluene decreases.
On the other hand, when it is 7 or more, it is difficult to dissolve in a fluorine-based solvent, but the solubility in an organic solvent such as toluene increases, which is effective for application to a coating type magnetic recording medium and the like. Also, n is 1 to 2
0 is suitable, and when it is more than 0, the solubility in the solvent decreases, and similarly, it becomes difficult to form a lubricating film on the tape surface. If the optimum solvent is used and the lubricating layer is formed with the balance of Rf, R1, R2 and n, there is no problem in terms of characteristics.

The average molecular weight of Rf is suitably 500 to 6000, preferably 1000 to 4000. If the average molecular weight is less than 500, the perfluoropolyether group is too short and the friction coefficient is large, and the average molecular weight is 6000. When it is larger than the above range, the solubility in the organic solvent decreases, and it becomes impossible to form a lubricating film on the tape surface using the organic solvent.

The perfluoropolyether compound of the present invention includes, for example, a compound containing a perfluoroether group (Rf) in the general formula (1) and R in the general formula (1).
It is easy to remove impurities and unwanted substances by mixing 1, 1 and amine compounds containing R2, heating at 100 ℃ and reacting to remove impurities and unnecessary substances by washing with an organic solvent and washing with a separating funnel. Can be synthesized.

As the compound containing the perfluoropolyether group (Rf) in the general formula (1), commercially available compounds can be used. Examples include Z-diac 2000 and Z-diac 4000 manufactured by Ausimont Co., Ltd. The Z-diac 2000 is HOOC (CF2CF2O) as a structural formula.
It is a compound having an average molecular weight of 2000 having m (CF2O) nCOOH (Z-diac 4000 is a compound having the same structural formula as Z-diac 2000, but the average molecular weight is 4000).

Further, as described above, the perfluoropolyether compound of the present invention can be preferably used as a lubricant for recording media, especially magnetic recording media (Japanese Patent Laid-Open Nos. 61-155345 and 61-61345). -113126, JP-A-62-270019, JP-A-2-101626).

In the magnetic recording medium to which the present invention is applied, a magnetic layer is formed by a coating film of a magnetic coating material containing a binder and a ferromagnetic powder as main components and an organic lubricant on a non-magnetic support. Applied to a coated magnetic recording medium or a metal thin film magnetic recording medium in which a metal magnetic thin film and a lubricant layer containing an organic lubricant are formed on the nonmagnetic support. It is possible. Further, both can be applied not only to tape but also to floppy disk (registered trademark) or hard disk.

Examples of the method for forming the lubricant layer include a dipping method, a spin coating method, a magnetic layer, and an internal addition method in the back layer. The coating amount of the lubricant is, for example, 0.
5 to 100 mg / m ² is preferable, and 1 to 20 mg / m ² is more preferable. For application, a lubricant dissolved in an organic solvent such as hexane can be used. When a rust preventive agent or the like is used, it may be combined with a lubricant, but if the rust preventive agent is applied on the carbon film and then the lubricant is applied to provide two or more layers, the rust preventive effect is obtained. Is preferred, which is preferable.

By the way, as the other materials forming the non-magnetic support, the magnetic layer and the like in the magnetic recording medium, any conventionally known materials can be used and are not particularly limited. In the case of a coating type magnetic recording medium, for example, as the non-magnetic support, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate,
Polyolefins such as polypropylene, celluloses such as cellulose triacetate and cellulose diacetate, vinyl resins, polyimides, polyamides, polycarbonates, films made of a polymer material typified by polyphenylene sulfide are preferably used. is there. The thickness of such a non-magnetic support is 1.0 to 200 μm, preferably 2.0 to 100 μm.
It is suitable as m.

When the magnetic recording medium has a coating type magnetic layer, the magnetic layer is formed by coating a magnetic paint mainly containing magnetic powder and a binder. , Γ-Fe2 O3, Fe3 O4, γ-
Betride compound of Fe2 O3 and Fe3 O4, Co
Containing γ-Fe2 O3, Co-containing Fe3 O4, Co-containing γ-Fe2 O3 and Fe3 O4 beltride compound, CrO2 containing one or more metal elements such as Te, Sb, Fe, Bi Examples of the oxide include: Furthermore, metals such as Fe, Co, and Ni, Fe
-Co, Fe-Ni, Fe-Co-Ni, Fe-Co-
B, Fe-Co-Cr-B, Mn-Bi, Mn-Al,
Fe-Co-V, Fe-Al, Fe-Ni-Al, Fe
-Al-P, Fe-Ni-Si-Al, Fe-Ni-S
i-Al-Mn, Fe-Mn-Zn, Fe-Ni-Z
n, Co-Ni, Co-P, Fe-Co-Ni-Cr,
Examples include alloys such as Fe-Co-Ni-P, and ferromagnetic metal powders such as iron carbide and iron nitride.

Such ferromagnetic metal powder can be obtained by reducing the oxides, hydrous oxides, inorganic salts, organic acid salts, etc. of the above metal elements in the gas phase with a reducing gas, or by the wet reduction method. Can be obtained by In producing the ferromagnetic metal powder, an appropriate amount of a light metal element such as Al, Si, P, B may be added for the purpose of preventing sintering during reduction or maintaining the shape. After the reduction, the surface is thin by a method of impregnating with an organic solvent and drying, a method of soaking in an organic solvent and blowing an oxidizing gas to dry it, and a method of blowing an oxidizing gas with a partial pressure adjusted without using an organic solvent. An oxide film is formed to provide oxidative stability. The oxide film formed on the surface is not limited to the constituent elements of the above-mentioned metal or alloy, but also Al, Si, Ca, Mg, Sr, Ba,
B, S, Ti, Zn, Na, Zr, K, Y, La, C
e, Pr, Nd, Sm, Gd, Ge, Sn, Ga, etc. may be contained.

Further, as the magnetic powder, in addition to the above oxides and ferromagnetic metal powders, hexagonal plate-shaped ferrite can be used. Examples of the hexagonal plate-shaped ferrite include M-type, W-type, Y-type, Z-type barium ferrite, strontium ferrite, calcium ferrite, lead ferrite, and the like, and Co- Ti, Co-Ti-Zn, Co-Ti-N
b, Co-Ti-Zn-Nb, Cu-Zr, Ni-Ti
It is also possible to use those to which etc. are added.

These magnetic powders may be used alone or in combination of two or more kinds.
It is desirable that the sizes of these magnetic powders are as follows. First, the specific surface area is preferably 35 m ² / g or more. Magnetic powder with a specific surface area in this range is
The particles are extremely fine, and by using such fine magnetic powder, high density recording is possible and noise is reduced. Further, particularly when the magnetic powder is acicular particles, the major axis length is preferably 0.05 to 0.50 μm and the axial ratio is preferably 2 to 15. If the major axis length is less than 0.05 μm,
Dispersion of magnetic powder in paint becomes difficult and the major axis length is 0.5
If it exceeds 0 μm, noise may increase. On the other hand, if the axial ratio is less than 2, the orientation of the magnetic powder is reduced and the output is reduced. On the contrary, when the axial ratio exceeds 15, the short wavelength signal output decreases.

On the other hand, when the magnetic powder is plate ferrite, the plate diameter is 0.01 to 0.5 μm and the plate thickness is 0.001 to 0.001.
It is preferably 0.2 μm. The major axis lengths, axial ratios, plate diameters and plate thicknesses of the magnetic powders shown above are calculated by randomly selecting 100 or more samples from transmission electron micrographs and calculating the average value thereof.

The binder contained in the magnetic layer may be a known thermoplastic resin, thermosetting resin, reactive resin or the like which has been conventionally used as a binder for magnetic recording media.
The number average molecular weight is preferably 5,000 to 100,000. As the thermoplastic resin, vinyl chloride, vinyl acetate,
Vinyl propionate, vinyl alcohol, maleic acid,
Acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, vinylidene chloride, acrylonitrile, methacrylonitrile, styrene, methylstyrene, butadiene, ethylene, vinyl acetal, vinyl butyral, vinyl ether, a polymer containing vinylpyrrolidone or the like as a structural unit or A copolymer is mentioned. Specifically, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinyl chloride-
Vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer,
Methacrylic acid ester-vinyl chloride copolymer, methacrylic acid ester-ethylene copolymer, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, styrene butadiene copolymer and the like can be mentioned. In addition, polyvinyl fluoride, polyamide resin, and further cellulose derivatives such as cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, and nitrocellulose, polyurethane resin, polyester resin, amino resin, synthetic rubber, etc. To be

Examples of the thermosetting resin or reactive resin include phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, polyamine resin and urea formaldehyde resin. .

A polar functional group may be introduced into all of these binders for the purpose of improving the dispersibility of the pigment component. As the polar functional group, -SO3M, -OSO3
M, -COOM, -P = O (OM) 2 (provided that M represents a hydrogen atom or an alkali metal such as lithium, potassium or sodium) and the like. Also, -NR1R
A side chain amine having a terminal group of 2, -NR1R2R3 + X-,
Alternatively, a main chain amine represented by> NR1R2 + X- (provided that R1, R2 and R3 represent a hydrogen atom or a hydrocarbon group, X- represents a halogen element ion such as fluorine, chlorine, bromine or iodine, or an inorganic substance). Ion or organic ion). Furthermore, as a polar functional group, -OH, -S
H, —CN, an epoxy group and the like can be mentioned. Although the above binders are used in the magnetic layer, these binders may be used alone or in combination of two or more kinds.

The magnetic powder and the binder as described above are dispersed in a solvent to form a magnetic coating material.
Acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and other ketone solvents, methanol, ethanol, propanol, butanol, isopropanol and other alcohol solvents, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, ethyl lactate, ethylene glycol Ester solvent such as acetate, diethylene glycol dimethyl ether, ether solvent such as 2-ethoxyethanol, tetrahydrofuran, dioxane, aromatic hydrocarbon solvent such as benzene, toluene, xylene, methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, Examples thereof include halogenated hydrocarbon solvents such as chlorobenzene and water.

A lubricant, an abrasive, a curing agent, a dispersant, an antistatic agent, an anticorrosive agent, etc. may be added to the magnetic paint as required. As the dispersant, the lubricant, the antistatic agent and the rust preventive, any conventionally known material can be used, and the dispersant is not limited at all. As the abrasive, aluminum oxide (α, β, γ), silicon carbide, chromium oxide, iron oxide, corundum, diamond, silicon nitride, titanium carbide, titanium oxide (rutile, anatase),
Examples include garnet, emery and boron nitride. These abrasives preferably have a Mohs hardness of 4 or more, preferably 5 or more and a specific gravity of 2 to 6, preferably 3 to.
The range of 5 is good. The average particle size is 0.5μ
m or less, preferably 0.3 μm or less. The average particle size is 100 at random from the transmission electromagnetic micrograph.
The average value is calculated by selecting more than the samples. The amount of these abrasives added is 20 parts by weight or less, preferably 10 parts by weight or less, relative to 100 parts by weight of the magnetic powder.

Carbon black is preferably used as the antistatic agent, and the strength of the coating film can be improved by adding carbon black. Further, as the dispersant, various surfactants or various coupling agents can be used.

As the curing agent, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and other alkylene diisocyanates,
Examples thereof include bifunctional isocyanate compounds such as xylene diisocyanate, naphthalene diisocyanate, and isophorone diisocyanate, or a reaction product of a polymer of these diisocyanates or a polyhydric alcohol. The amount of these curing agents added is 5 to 80 parts by weight per 100 parts by weight of the binder.
The amount is preferably 10 parts by weight, more preferably 10 to 50 parts by weight.

To prepare a magnetic paint, the above materials are made into a paint by a kneading step, a mixing step and a dispersing step. A roll mill, a ball mill, a sand mill, an agitator, a kneader, an extruder, a homogenizer, an ultrasonic disperser, or the like is used for the dispersing device and the kneading device. The magnetic coating material thus prepared is applied onto the non-magnetic support by an arbitrary method such as spraying or roll coating, and dried to form the magnetic layer.
After that, the magnetic layer may be introduced into a calendering device and subjected to surface smoothing treatment.

Here, the magnetic layer has a dry thickness of 0.1.
˜50 μm, preferably 1.0 to 30 μm. The mixing ratio of the binder and the magnetic powder is 1 to 10 parts by weight of the magnetic powder, preferably 3 to 9 parts by weight, relative to 1 part by weight of the binder. When the amount of the binder is too large, the ratio of the magnetic powder in the magnetic layer becomes relatively small, and the output decreases. Further, when the magnetic head and various sliding members are repeatedly slid on the drive, plastic flow easily occurs in the magnetic layer, and the running durability of the medium deteriorates. If the amount of the binder is too small, the magnetic layer becomes brittle, and the running durability of the medium deteriorates.

Further, in the case of a metal thin film type magnetic recording medium, for example, the same nonmagnetic support as the above-mentioned coating type magnetic recording medium can be used. In this case, when a rigid substrate such as an Al alloy plate or a glass plate is used as the non-magnetic support, an oxide film such as alumite treatment or a Ni-P film is formed on the substrate surface to harden the surface. You may do it. The metal magnetic thin film is formed as a continuous film by a PVD method such as plating, sputtering or vacuum deposition, and is made of a metal such as Fe, Co or Ni or Co-
Ni-based alloys, Co-Pt-based alloys, Co-Pt-Ni-based alloys, Fe-Co-based alloys, Fe-Ni-based alloys, Fe-Co
-Ni system alloy, Fe-Ni-B system alloy, Fe-Co-B
Examples include in-plane magnetization recording metal magnetic films and Co-Cr alloy thin films made of a system alloy, Fe-Co-Ni-B alloy, and the like.

In particular, in the case of in-plane magnetization recording metal magnetic thin film,
Bi, Sb, Pb, Sn, Ga, on the non-magnetic support in advance
An underlayer of a low melting point non-magnetic material such as In, Ge, Si, and Tl is formed in advance, and a metal magnetic material is vapor-deposited or sputtered from the vertical direction to diffuse the low melting point non-magnetic material in the metal magnetic thin film. The orientation may be eliminated to secure the in-plane isotropic property, and the coercive force may be improved.

As a method for forming the carbon film on the surface of the magnetic recording medium, sputtering is generally used, but the method is not particularly limited, and any method can be used. In this case, the thickness of the carbon film is preferably 2 to 100 nm, more preferably 5 to 30 nm.

As a method for holding the lubricating film structure on the carbon film on the surface of the magnetic recording medium, there may be mentioned a method of top-coating a lubricant layer on the surface of the carbon film.
In this case, the applied amount of the lubricant is 0.5 to 10
0 mg / m ² is desirable, 1-20 mg / m ²
Is more preferable. Further, the above lubricant may be used in combination with a rust preventive agent, if necessary. As the rust preventive, any rust preventive commonly used as a rust preventive for magnetic recording media of this type can be used, and examples thereof include phenols, naphthols, quinones, nitrogen atom-containing heterocyclic compounds, and oxygen atoms. And a heterocyclic compound containing a sulfur atom. The rust preventive agent may be used in combination with the lubricant, but the rust preventive agent layer is applied on the carbon film and then the lubricant agent layer is applied, so that the rust preventive agent is applied in two or more layers. Then the effect is high.

The perfluoropolyether compound of the present invention is preferably used as a lubricant for recording media, especially magnetic recording media as described above. However, the lubricant of the present invention can be applied not only to magnetic recording media but also to optical recording media, and its support is not limited to tapes and can be used for recording media such as disk media such as magnetic disks and optical disks. .

[Function] In the conventional lubricant, a compound having a relatively large polarity such as a carboxylic acid or an amine has a small friction coefficient, but the still durability tends to be poor.
A compound having a relatively small polarity such as ester is excellent in still durability, but has a large friction coefficient. The perfluoropolyether compound of the present invention has a strongly polar carboxylic acid amine salt, and has a hydroxyl group at the terminal portion, so that the carbon film surface has a strong adsorption force, a small friction coefficient, and a still It has excellent durability and shuttle durability. It has been known from previous studies that the amine salt of carboxylic acid contained in the structure has a strong intermolecular cohesive force and forms an aggregate at the molecular level. It has been clarified that such a material having a strong cohesiveness does not cause sticking of the tape and has a wide optimum amount range in which the durability can be sufficiently secured, and is an advantageous material from the industrial viewpoint of manufacturing control. . Furthermore, since it contains a hydroxyl group in the molecule,
Particularly when applied to a hard disk, a heat treatment is performed to chemically bond with the substrate and form a strong fixing layer. By having two different types of functional groups in the molecule in this way, a function that cannot be performed by itself can be exhibited.

Further, while a fluorine-based solvent is essential for applying a conventional fluorine-containing lubricant, the perfluoropolyether-based compound of the present invention can be formed by extending the alkyl chain length of R1 or R2. Since it can be coated with a hydrocarbon solvent such as toluene or acetone, the load on the environment is small. Therefore, it becomes possible to internally add to the magnetic layer or the back layer in the coating type magnetic recording medium which does not use a fluorine-based solvent, which is advantageous in terms of cost.

As described above, the magnetic recording medium using the perfluoropolyether compound of the present invention as a lubricant maintains excellent lubricity under various conditions of use, and has a long-lasting lubrication effect. It is possible to provide excellent runnability, wear resistance, durability and the like.

[Examples] The present invention is applied to a metal thin film type magnetic recording medium and will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples. Example of synthesis of perfluoropolyether compound of the present invention

[0046]

[Chemical 7]

Z-diac2000 is used as the compound containing the perfluoropolyether group (Rf) in the general formula (1), and 2-Dimethylaminoethanol is used as the amine compound containing R1 and R2 in the general formula (1). The perfluoropolyether compound of was synthesized (formula (2)). The synthetic procedure is shown below.

2-Dimethylaminoethanol 3.5 g and Z-di
30 g of ac2000 was mixed and refluxed at 100 ° C. for 3 hours. After completion of the reaction, the mixture was placed in a separating funnel, 200 ml of Fluorinate (3M) and 200 ml of hexane were added, and liquid separation washing was performed. Unreacted 2-Dimethylaminoe soluble in hexane
The thanol was removed, and the fluorinate layer in which the target substance was dissolved was collected and concentrated to obtain the target substance. The collected product was IR analysis, peaks disappeared completely by carboxyl group which has been observed near 1780 cm ^-1, the absorption of the carboxylic acid amine salt was confirmed in the vicinity of 1690 cm ^-1, the formula (2) It was found to be a perfluoropolyether compound. The recovered product was 30.1 g, and the recovery rate was about 92%.

If a method similar to the above is adopted, any perfluoropolyether group (R
The perfluoropolyether compound of the present invention can be synthesized by arbitrarily setting f) and R1 and R2 groups. Specific examples thereof are shown in Table 1 below.

[0050]

[Table 1]

Examples 1 to 16 Perfluoropolyether compounds of the present invention were synthesized by using the raw materials shown in Table 2 below in the same procedure as in the above-described synthesis example, and the compounds were used as lubricants in the following tests.

[0052]

[Table 2]

Comparative Examples 1 to 5 The compounds having the structures shown in Table 3 below were used as lubricants and subjected to the following tests.

[0054]

[Table 3]

Preparation of sample tape Co was adhered to a 7.0 μm thick polyethylene terephthalate film by the above-mentioned oblique vapor deposition method to give a film thickness of 180 n.
m metal magnetic thin film was formed. Then, a carbon protective film having a thickness of about 8 nm was formed on the metal magnetic thin film by using the magnetron sputtering device described above. Then, a 0.5 μm thick back coat layer made of carbon and polyurethane resin was formed on the surface of the polyethylene terephthalate film opposite to the surface on which the metal magnetic thin film was formed.
Next, a solution obtained by dissolving the compounds shown in Tables 1 or 2 and 3 in toluene or HFE 7200 (3M Company) was applied to the surface of the carbon protective film so that the coating amount was 5 mg / m ² . . The obtained magnetic recording medium was cut into a width of 6.35 mm to prepare a sample tape as an example.

<Evaluation of Durability and Runnability> Using each of the sample tapes produced as described above, a temperature of 40
The friction coefficient was measured under conditions of temperature of 80 ° C and humidity of 80%, still durability was measured under conditions of temperature of -5 ° C, and shuttle durability was measured under conditions of temperature of 40 ° C and humidity of 20%. The results are shown in Table 4.
In the evaluation by the present inventors, the environmental conditions for each measurement were determined because the above environmental conditions are the most severe environmental conditions. For measuring still durability and shuttle durability, a commercially available digital video camcorder (VX manufactured by Sony
1000) was used.

(1) Friction coefficient measuring method The friction coefficient was measured in a constant temperature bath at a temperature of 40 ° C. and a humidity of 80%.
The sample tape was run for 100 passes under the control of RH and measured. The numerical value at the 100th pass of friction running is shown in the table as a friction coefficient. (2) Still Durability Measurement Method The still durability was measured in a constant temperature bath at -5 ° C, and the time until the reproduction output dropped by 3 dB was measured. (3) Shuttle durability measurement method Shuttle durability is measured at a temperature of 40 ° C and a humidity of 20% R in a constant temperature bath.
The sample tape was controlled to H, the sample tape was run for 60 minutes on a 100-path shuttle, and after the 100-path was run, how much dB the reproduction output dropped from the initial output was measured.

[0058]

[Table 4]

From the above results, by using the perfluoropolyether compound of the present invention as a lubricant for magnetic recording media, the friction coefficient and the still durability under various use conditions such as high temperature and high humidity, high temperature and low humidity, and low temperature. It can be seen that very good results were obtained with very little deterioration in the durability or shuttle durability.

[0060]

The perfluoropolyether compound of the present invention is particularly useful as a lubricant for magnetic recording media. In addition, a ferromagnetic metal material is deposited on the non-magnetic support by a method such as vapor deposition, and the non-magnetic support is used as a magnetic layer to form a so-called metal thin film type magnetic recording medium or a very fine magnetic recording medium. By applying a magnetic coating material containing particles and a resin binder onto a non-magnetic support and using the perfluoropolyether compound as a lubricant in a so-called coating type magnetic recording medium having this as a magnetic layer. It is possible to obtain a magnetic recording medium capable of maintaining excellent lubricity under various conditions, maintaining a lubricating effect for a long time, and providing excellent running properties, abrasion resistance, durability and the like.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10N 30:06 C10N 30:06 40:18 40:18 (72) Inventor Ken Kobayashi Kita-Shinagawa, Shinagawa-ku, Tokyo 6,7-35, Sony Corporation (72) Inventor Hiroshi Iwamoto 6-7, Kita-Shinagawa, Shinagawa-ku, Tokyo 6-35, Sony Corporation (72) Inventor Toshinori Tsuboi 6, Kita-Shinagawa, Shinagawa-ku, Tokyo No. 7-35 F term in Sony Corporation (reference) 4H104 BD07A CD04A LA03 LA20 PA16 4J005 BA00 BD05 5D006 BA09

Claims (4)

[Claims] 1. The following general formula (1): (In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. And an integer of 1 to 20.). 2. The following general formula (1): (In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. A lubricant for a recording medium comprising a perfluoropolyether compound represented by the formula (1 to 20). 3. A recording medium comprising a support and at least a recording layer and a lubricant layer made of a lubricant, wherein the lubricant is represented by the following general formula (1): (In the formula, Rf represents a perfluoropolyether group having an average molecular weight of 500 to 6000, R1 and R2 represent hydrogen, a hydrocarbon group, a partially fluorinated hydrocarbon group, or a fluorocarbon group. A recording medium containing a perfluoropolyether compound represented by the formula (1 to 20). 4. The recording medium according to claim 3, wherein the recording layer is a magnetic layer, and the recording medium is a magnetic recording medium.