JPH1081888A - Lubricant and magnetic recording medium using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant which is excellent in lubricity and effective in removing brown stain adhering to a head by using a fatty acid ester compd. having a dialkylamino group and an arom. ring. SOLUTION: This lubricant comprises a fatty acid ester compd. represented by the formula (wherein R<1> is alkyl; R<2> is an alkylene group having an arom. ring introduced thereinto; and R<3> and R<4> are each a hydrocarbon group). The compd. is synthesized by the esterification of a long-chain carboxylic acid with an alcohol having a dialkylamino group and an arom. ring. The esterification is carried out by e.g. the dehydration in toluene or by converting the carboxylic acid into an acid chloride and esterifying the acid chloride in the presence of a base as the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant and a magnetic recording medium using the same, and more particularly to an improvement in running durability of the magnetic recording medium.

[0002]

2. Description of the Related Art In a so-called metal magnetic thin film type magnetic recording medium in which a magnetic layer is formed by depositing a ferromagnetic metal material on a nonmagnetic support by a method such as vapor deposition, the magnetic layer is made of a ferromagnetic material. Compared to a coating-type magnetic recording medium composed of powder and a binder, it has excellent magnetic properties, such as higher packing density of a magnetic material in a magnetic layer, and is used in various magnetic recording systems in recent years. It has become.

[0003] The magnetic recording medium of the metal magnetic thin film type has an extremely high smoothness on the surface of the magnetic layer, and therefore has a substantial contact area with a sliding member such as a magnetic head or a guide roller. Also becomes a large value. For this reason, there is a problem in that a sticking phenomenon (so-called sticking) easily occurs with these sliding members during running and the running property and durability are poor. For example, when applied to an 8 mm video deck or a hard disk drive, the following problems occur.

First, a tape inserted into an 8 mm video deck is guided by ten or more guide pins and wound around a head drum. At this time, the tape tension and the tape running speed are kept constant by a pinch roller and a capstan. Usually, the tension is set to about 20 g and the running speed is set to 0.5 cm / s.

[0005] The running system has a structure in which the magnetic layer side of the tape is in contact with a guide pin made of stainless steel. In such a case, if the coefficient of friction between the surface of the magnetic layer of the tape and the guide pins is large, the tape causes stick-slip, a phenomenon called tape squealing, and the reproduced image becomes cramped.

Further, the relative speed between the tape and the head is very high, and particularly in the pause state, the head slides at the same position on the tape at a high speed. This causes a problem of abrasion of the magnetic layer and a resulting reduction in reproduction output. In the above-described metal magnetic thin film type magnetic tape, the magnetic layer is very thin, so that the wear of such a magnetic layer is very serious.

On the other hand, in a hard disk drive,
The SS (contact start / stop) method is adopted. In the CSS method, when the disk is stopped, the magnetic head is in contact with the disk. When the disk is rotated at a high speed at the time of startup, the magnetic head floats from the surface of the disk due to the airflow generated thereby, and recording is performed in this state Playback is performed. When the operation is stopped, the rotation of the disk is further reduced, whereby the magnetic head comes into contact with the disk again. CSS like this
In the method, at the time of startup, from the start of disk rotation until the magnetic head floats, and at the time of operation stop, from the time the magnetic head contacts the disk until the disk stops rotating, The magnetic head slides on the disk. At that time, friction between the magnetic head and the disk becomes a major problem. C to maintain product level reliability
It is desirable that the friction coefficient after performing the SS operation 20,000 times is 0.5 or less, but it is difficult to satisfy this condition with a metal magnetic thin film type magnetic disk having high surface smoothness. Another problem to be solved is head crash caused by collision between the head and the disk.

[0008] In order to solve such problems, attempts have been made to suppress the friction coefficient by top-coating the magnetic layer with various lubricants such as higher fatty acids and esters thereof.

Here, the lubricant used for the magnetic recording medium is required to have the following extremely strict conditions for its use. However, conventionally used lubricants cannot be said to sufficiently satisfy such conditions.

That is, the lubricant used for the magnetic recording medium has (1) excellent low-temperature characteristics so as to ensure a predetermined lubricating effect when used in a cold region; (2)
It can be applied very thinly because spacing with the magnetic head is a problem, and sufficient lubrication performance can be exhibited even in that case. (3) It can withstand long-time use and maintain the lubrication effect for a long time. , Etc. are required.

That is, as a lubricant for a magnetic recording medium,
As well as having good lubrication performance against sliding with the head, it can be uniformly and firmly adhered to the surface of the magnetic layer, and the lubrication performance can be maintained for a long period of 10 years or more. Ideally, a film that can be applied as a thin film on the order of several nanometers on the order of a single molecule is ideal.

It is known that the lubricating performance of a lubricant depends on its molecular structure. However, as a lubricant for a magnetic recording medium, a large number of compounds have been developed so far. System, hydrocarbon system and fluorinated carbon system.

First, silicon-based lubricants are one of the lubricants widely used in coating type magnetic recording media because of their good thermal stability and low vapor pressure. However, when used for a magnetic recording medium of a metal magnetic thin film type with very good surface properties, not very good lubrication performance is obtained, and the durability specification in the pin-on-disk wear acceleration test or CSS test is Not satisfied. That is, it is difficult for a silicon-based lubricant to form a lubricating film oriented on the surface of a thin-film magnetic recording medium, which is currently the mainstream, and to satisfy required lubrication characteristics.

Hydrocarbon lubricants are still the mainstream lubricants in coating type magnetic recording media. However, this hydrocarbon-based lubricant is generally inferior in thermal or chemical stability as compared with a silicon-based or fluorinated carbon-based lubricant. Also, the friction reacts with the lubricant molecules to produce a frictional polymer. This frictional polymer is very troublesome, degrading lubricating properties and sometimes causing catastrophic failure. Another disadvantage is that the hydrocarbon-based lubricant has a high vapor pressure.
That is, the hydrocarbon-based lubricant exhibits excellent friction characteristics, but gradually evaporates due to its high vapor pressure. For this reason, in a magnetic recording medium of the metal magnetic thin film type in which the lubricant is held only by top-coating the lubricant, if the lubricant volatilizes from the surface, it is not replenished, and it is difficult to maintain the lubrication performance. is there.

Fluorine-based lubricants are currently the most frequently used lubricants in metal magnetic thin film type magnetic recording media. Among the fluorine-based lubricants, particularly, perfluoropolyether is widely used because of its better lubricating performance and surface protection effect as compared with other fluorine-based lubricants.
The perfluoropolyether has such good properties because of the flexibility of the CF ₂ —O—CF ₂ ether bond, the viscosity is lower than that of perfluoroalkane of the same molecular weight, and over a wide temperature range. This is because the viscosity does not change. In addition, it must be chemically inert, have low vapor pressure, have high thermal or chemical stability, have low surface energy,
The features include good boundary lubrication characteristics and high water repellency.

Here, the properties of the above perfluoropolyether very strongly depend on its molecular structure. Currently, several types of perfluoropolyethers are commercially available, but differ in molecular weight, main chain repeat units, and end groups.

[0017] For example, Fomb, trade name, manufactured by Ausimont
lin-Y is a random copolymer of CF (CF ₃ ) CF ₂ O and CF ₂ O, and the main chain repeating unit has a branched structure. On the other hand, the company's product name “Fombli”
n-Z is a homopolymer of CF ₂ CF ₂ O and CF ₂ O and has a linear structure. Due to this linear structure, the viscosity becomes low and the lubricating properties are superior to those of other types. Made by Daikin Industries, trade name demnum and made by Dupont, trade name K
rytox is a homopolymer of hexafluoropropylene oxide and hexafluoroisopropylene oxide, respectively. This type has a higher viscosity in comparison with Fomblin-Z, but has better chemical stability.

On the other hand, since perfluoropolyether is relatively inert chemically, it has a drawback that it lacks adsorption ability on the surface of a magnetic medium. Therefore, in order to improve the adsorptive power, a perfluoropolyether having polar groups introduced at both ends is available as Fomblin (trade name, manufactured by Ausimont)
Z-DOL (introducing a hydroxyl group as a polar group) and Fomblin AM2001 (trade name, a piperonyl group as a polar group) manufactured by the company have been developed. Of these, Fom
Blin AM2001 has a very strong immobilizing action, especially on metal and carbon surfaces. For this reason, when used as a lubricant, a large friction coefficient reduction effect is obtained compared to unmodified perfluoropolyether,
The service life of the media is improved.

[0019]

Although various studies have been made on lubricants as described above, they cannot be said to be satisfactory.

For example, with respect to the thermal and chemical stability required for a lubricant, in some magnetic recording systems, the relative speed between the medium and the magnetic head exceeds several meters, and the friction generated at the contact portion is large. The temperature of the medium surface may increase instantaneously but rapidly due to heat. The temperature at the contact is estimated to exceed several hundred degrees Celsius, although the exact method of measurement has not yet been established. Especially,
Under boundary lubrication conditions, such as in magnetic recording systems,
Since the reactive surface is exposed at the sliding portion, this is combined with the temperature rise at the above-mentioned contact point, thereby promoting the decomposition reaction of the lubricant molecules.

Here, the perfluoropolyether is stable in air even at a temperature of 350 ° C. or more, but is preferably a metal alloy such as iron or titanium alloy, or a Lewis acid or Lewis base such as AlCl ₃ , FeF ₃ or Al _2. Decomposition becomes easy in the presence of O ₃ .

When the relative speed between the head and the medium is increased in this way, seizures adhere to the sliding surface of the magnetic head on the magnetic recording medium. This burn-in product is called brown stain, and it is considered that the metal magnetic powder transferred from the magnetic layer to the head is attached as γ-Fe ₂ O ₃ . The brown stain causes a spacing loss between the head and the magnetic layer, and significantly deteriorates the reproduction output. Lubricants are also expected to have such an effect of removing brown stain, but at present, lubricating agents such as perfluoropolyether cannot provide such an effect.

Accordingly, the present invention has been proposed in view of such a conventional situation, and has an effect of exhibiting good lubricating performance even under severe use conditions and removing brown stain adhering to the head. It is an object to provide a lubricant having the same. It is another object of the present invention to provide a magnetic recording medium which is excellent in running durability by using such a lubricant, and in which a level decrease due to brown stain is suppressed.

[0024]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies and found that a fatty acid ester compound having a dialkylamino group and an aromatic ring is
It has been found that it has excellent lubrication performance and has an effect of removing brown stain attached to the head.

The present invention has been completed based on such findings. That is, the lubricant of the present invention is a fatty acid ester-based compound represented by Chemical Formula 3.

Further, the magnetic recording medium of the present invention is characterized in that the fatty acid ester compound represented by Chemical Formula 3 is held in a magnetic layer or a protective film.

[0027]

Embedded image

The fatty acid ester compound represented by Chemical Formula 3 exhibits good lubricating performance not only under normal temperature and normal humidity but also under severe environments such as high temperature, high humidity and low temperature. In particular, the introduction of an aromatic ring into the alkylene group forming between the ester bond and the dialkylamino group has an effect of removing brown stain attached to the head.

Therefore, when such a lubricant is held in the magnetic layer or the protective film of the magnetic recording medium, the running durability of the magnetic recording medium is improved, and the level reduction due to brown stain can be suppressed.

[0030]

Embodiments of the present invention will be described below.

The lubricant of the present invention is a fatty acid ester compound comprising a long-chain carboxylic acid and an alcohol having a dialkylamino group and an aromatic ring introduced therein, and is represented by the following general formula.

[0032]

Embedded image

In the chemical formula 4, the long-chain alkyl group R ¹ of the long-chain fatty acid portion preferably has 10 to 30 carbon atoms. If the number of carbon atoms is less than 10, sufficient lubrication performance cannot be obtained. On the other hand, when it exceeds 30, the production becomes difficult, and it is not practical.

[0034] R ³ of the amino group R ⁴ is important that a hydrocarbon group. When R ³ and R ⁴ are hydrogen, the amino group reacts with the hardener of the magnetic paint to deteriorate the paint properties. The molecular weight and carbon number of R ³ and R ⁴ are not particularly limited.
In addition, the presence or absence of a branched structure, unsaturated bond, aromatic ring, isomer type and alicyclic structure can be freely selected.

The region between the amino group and the ester group is constituted by an alkylene group into which an aromatic ring has been introduced. The alkylene group preferably has 1 to 12 carbon atoms. The alkylene group may be linear or have a branched structure. In particular, the lubricant exhibits an effect of removing brown stain attached to the head due to the introduction of the aromatic ring into the alkylene group. This aromatic ring may be a heterocyclic ring containing nitrogen, oxygen or sulfur, in addition to benzene, naphthalene and anthracene.
At least one aromatic ring is required, but 4
If more than one is introduced, the effect is not further increased, so it is appropriate to set it to 1 to 3. Further, the aromatic ring may be introduced adjacent to an ester group or an amino group, or may be introduced between alkylene groups. The position at which the alkylene group, ester group, or amino group is bonded to the aromatic ring is not particularly limited. For example, in a benzene ring, it may be any of the o-, m-, and p-positions.

Such a fatty acid ester compound is synthesized by subjecting a long-chain carboxylic acid to an esterification reaction of an alcohol having a dialkylamino group and an aromatic ring.

For this esterification, a method of dehydration in toluene or an acid chloride of carboxylic acid,
There is a method of esterification using a base as a catalyst.

The above-mentioned lubricant is retained in, for example, a magnetic layer of a magnetic recording medium. When this lubricant is held in the magnetic layer of the magnetic recording medium, good running durability can be obtained not only under normal temperature and normal humidity but also under severe environments such as high temperature, high humidity and low temperature. Further, since the brown stain adhering to the head is removed by the lubricant, the level reduction due to the brown stain is prevented.

A magnetic recording medium to which such a lubricant is applied has a magnetic layer formed by depositing a ferromagnetic metal material on a non-magnetic support by a vacuum thin film forming technique such as vapor deposition. Even in a thin film type magnetic recording medium, a magnetic layer is formed by applying a magnetic paint prepared by mixing a ferromagnetic powder and a binder together with an organic solvent on a non-magnetic support. May be used.

The following materials are used as constituent materials of the metal magnetic thin film type magnetic recording medium.

First, as the nonmagnetic support, polyesters such as polyethylene terephthalate, polyethylene,
Polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate; vinyl resins such as polyvinyl chloride and polyvinylidene chloride; plastics such as polycarbonate, polyimide, polyamide, and polyamideimide; paper; and aluminum. , Metal such as copper, aluminum alloy, light metal such as titanium alloy, ceramic,
Single crystal silicon, glass, or the like is used. When a rigid substrate such as an aluminum alloy plate or a glass plate is used, an oxide film such as alumite treatment or a Ni-P film may be formed on the substrate surface to make the surface hard. .

As the metal magnetic thin film, Fe, Co, Ni
Such as metals, Co-Ni alloys, Co-Pt alloys, Co
-Pt-Ni alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Ni-B alloy, Fe-Co-B alloy, Fe-Co-Ni-B An in-plane magnetization recording metal magnetic film made of a system alloy or the like and a perpendicular magnetization recording metal magnetic thin film made of a Co—Cr alloy or the like are exemplified.

These ferromagnetic metal materials are formed as a continuous film by a PVD technique such as plating, sputtering, or vacuum deposition.

In the case of the in-plane magnetization recording type metal magnetic thin film among the metal magnetic thin films thus formed, Bi, Sb, Pb, Sn,
An underlayer of a low-melting nonmagnetic material such as Ga, In, Ge, Si, or Ti may be formed. When a ferromagnetic metal material is vapor-deposited or sputtered from above on the underlayer, the low-melting non-magnetic material diffuses into the metal magnetic thin film, the orientation is eliminated, and the in-plane isotropy is secured. And the coercivity is improved.

In order to hold the above lubricant on such a metal magnetic thin film, a method of top-coating the lubricant on the surface of the metal magnetic thin film is used. In this case, the coating amount of the lubricant film is 0.5 to 100 mg / m ² , more preferably 1 to 20 mg / m ² .
mg / m ² is good. If the amount of the lubricant film applied is too small, a sufficient effect cannot be obtained. On the other hand, if the amount of the lubricant applied is too large, it may cause sticking to the head.

Although the above is the basic structure of the magnetic recording medium, the magnetic recording medium may be further provided with a protective film on a metal magnetic thin film. As the protective film, a hard protective film such as a diamond-like or amorphous carbon film, a chromium oxide film, a SiO ₂ film, and a ZrO ₂ film is provided. In this case, the lubricant is retained on the protective film. The method and conditions for retaining the lubricant in the protective film may be the same as those for retaining the lubricant in the metal magnetic thin film.

The above lubricant may be used in combination with a lubricant generally used in a magnetic recording medium. Examples of such lubricants include long-chain carboxylic acids or esters thereof, long-chain alcohols, long-chain amines, and the like.

In addition, it is also possible to use together with an extreme pressure agent and a rust inhibitor.

The extreme pressure agent reacts with the metal surface due to the frictional heat generated when partial metal contact occurs in the boundary lubrication region, and exhibits an action of preventing friction and wear by forming a reaction product film. Things. Examples of such extreme pressure agents include phosphorus extreme pressure agents, sulfur extreme pressure agents, halogen extreme pressure agents, organometallic extreme pressure agents, and complex extreme pressure agents. These extreme pressure agents are used in an amount of 30:70 to 7 with respect to the lubricant.
It is appropriate to use a weight ratio of 0:30.

As the rust preventive, those usually used as rust preventives for this type of magnetic recording medium, for example, phenols, naphthols, quinones, heterocyclic compounds containing a nitrogen atom, heterocyclic compounds containing an oxygen atom And heterocyclic compounds containing a sulfur atom.

The magnetic recording medium may further have an additional structure in which an undercoat layer is formed between the nonmagnetic support and the magnetic layer, or a metal magnetic thin film of the nonmagnetic support is formed. A back coat layer may be formed on the surface opposite to the opposite side. For example, the back coat layer is formed by dispersing a carbon-based fine powder for imparting conductivity or an inorganic pigment for controlling surface roughness in a resin binder. When this back coat layer is provided, a lubricant may be applied to this layer or may be internally added.

On the other hand, in a coating type magnetic recording medium, a magnetic layer is formed by applying a magnetic paint prepared by mixing a ferromagnetic powder and a binder together with an organic solvent on a non-magnetic support.

As the non-magnetic support, any of those exemplified for the metal magnetic thin film type magnetic recording medium can be used.

The following are used as the ferromagnetic powder and the binder constituting the magnetic layer.

First, as the ferromagnetic powder, γ-Fe
_{In addition to 2} O ₃ , Fe ₃ O ₄ , Co-modified iron oxide, synthetic fine powder containing iron as a main component, modified barium ferrite, modified strontium ferrite and the like are used.

As the binder, a modified or unmodified vinyl chloride resin, polyurethane resin or polyester resin can be used alone or as a mixture. Further, a cellulose resin, a phenoxy resin or a thermoplastic resin, a thermosetting resin, a reactive resin, or an electron beam irradiation curable resin may be used in combination.

The groups introduced for modifying the resin include -SO ₃ M,-for the purpose of improving the dispersibility of the magnetic powder.
_{OSO 3 M, -COOM, -PO (} OM') 2 ( However, M
Represents an alkali metal atom such as Na, and M ′ represents an alkali metal atom such as Na or an alkyl group).

The solvent for coating may be an organic solvent selected from ethers, esters, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, chlorinated hydrocarbons and the like.

The above-mentioned lubricant may be held in such a coating type magnetic layer by a method of top-coating the lubricant in the same manner as in the case of the metal magnetic thin film type magnetic recording medium. You may make it add internally by adding. When added internally, the amount of the lubricant is suitably from 0.1 to 10% by weight, preferably from 1 to 4% by weight, based on the ferromagnetic powder.

If necessary, a dispersant such as lecithin, a lubricant such as long-chain carboxylic acid, an antistatic agent such as carbon black, and an abrasive such as chromium oxide may be added to such a coating type magnetic layer. A rust inhibitor may be added. As the dispersant, the lubricant, the antistatic agent, and the rust preventive, any conventionally known materials can be used other than those exemplified above.

Also in this coating type magnetic recording medium, an undercoat layer is formed between the nonmagnetic support and the magnetic layer, or the nonmagnetic support is opposite to the side on which the magnetic layer is formed. A back coat layer may be formed on the side surface. Also in this case, a lubricant may be applied to the back coat layer or may be internally added.

[0062]

EXAMPLES Hereinafter, specific examples of the present invention will be described based on experimental results.

Synthesis of Lubricant C ₁₇ H ₃₅ COOCH ₂ CH ₂ PhN (CH
₃ ) A lubricant (compound 1) having a structure of ₂ was synthesized.

Dimethylaminophenylethanol and stearic acid chloride were esterified in the presence of triethylamine. After the completion of the reaction, the resultant was washed with water to remove the solvent. Then, the reaction product was purified by silica gel chromatography, and recrystallized from hexane. FIG. 1 shows the infrared absorption spectrum of the obtained product. This way the infrared absorption spectrum, the absorption peak absorption peak attributable to C-H stretching vibration appeared at around 2920 cm ^-1 and 2850 cm ^-1, attributable to carbonyl group 1740c
m ^-1 appears. From this, it was confirmed that the target ester compound was produced by this reaction.

Subsequently, R ¹ —COOR ² N (R ³ ) (R ⁴ )
In Table 1, various lubricants (compounds 2 to 6) having R ¹ , R ² , R ³ and R ⁴ shown in Table 1 were synthesized by reacting an alcohol having an amino group and an aromatic ring with acid chloride.

[0066]

[Table 1]

(However, Ph represents a benzene ring.) The characteristics of these lubricants were studied in Examples 1 to 12 and Comparative Examples 1 to 4 below.

Example 1 A 10 μm thick polyethylene terephthalate film was
Co was deposited by oblique deposition to form a 200 nm thick ferromagnetic metal thin film.

Next, on the surface of the metal magnetic thin film, Compound 1 was added.
Was dissolved in n-hexane at a coating amount of 5 mg / m ² and then cut into 8 mm width to prepare a sample tape.

Examples 2 to 6 Sample tapes were prepared in the same manner as in Example 1 except that Compounds 2 to 6 were used as lubricants.

Comparative Example 1 A sample tape was prepared in the same manner as in Example 1 except that butyl stearate was used as a lubricant.

Comparative Example 2 Example 1 except that stearic acid was used as a lubricant.
A sample tape was produced in the same manner as described above.

The coefficient of friction, still durability, and the like of the sample tape prepared as described above were measured under various conditions at a temperature of -5 ° C, a temperature of 25 ° C and a relative humidity of 60%, and a temperature of 40 ° C and a relative humidity of 80%. Shuttle durability was measured. The results are shown in Tables 2 and 3. The measurement conditions for the coefficient of friction, still durability, and shuttle durability are as follows.

Coefficient of friction: The coefficient of dynamic friction with respect to the stainless steel guide. This stainless guide has a surface roughness of 0.2 s and a diameter of 4 mm. The tape has a running speed of 5 mm / sec and a load of 50 g / 8 mm.

Shuttle durability: The tape was used for 2 cycles per cycle.
It was evaluated by counting the number of repetitions until the output decreased by 3 dB. The video deck used for the measurement was a SONY 8 mm VTR / EV-S55. The measurement signal is a color bar image signal and the output signal is RF
Output.

Still durability: Still reproduction was performed, and evaluation was performed by measuring the time until the output decreased by 3 dB.
The VCR, measurement signal and output signal used in the measurement are the same as those used in the evaluation of shuttle durability.

[0077]

[Table 2]

[0078]

[Table 3]

As can be seen from Tables 2 and 3, the sample tapes of Examples 1 to 6 in which a fatty acid ester compound having a dialkylamino group and an aromatic ring was used as a lubricant under any conditions Low coefficient, excellent in still durability and shuttle durability.

On the other hand, the sample tape of Comparative Example 1 using butyl stearate as a lubricant and the sample tape of Comparative Example 2 using stearic acid as a lubricant were compared with the sample tapes of these Examples. The coefficient of friction is large, and the still durability and shuttle durability are inferior particularly in a high temperature and high humidity environment or a low temperature environment.

From this, it was found that the fatty acid ester compound having a dialkylamino group and an aromatic ring was superior in lubricating performance as compared with other lubricants.

Example 7 Composition of Magnetic Paint Metal magnetic powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer 10.5 parts by weight Polyurethane resin 10.5 parts by weight Carbon (antistatic agent) 5 parts by weight Methyl ethyl ketone 150 parts by weight Methyl Isobutyl ketone 150 parts by weight After the above composition was mixed by a ball mill for 24 hours,
Passed through the filter. Subsequently, 4 parts by weight of Coronate L (a polyisocyanate manufactured by Nippon Polyurethane Industry Co., Ltd.) was added as a curing agent to the filtrate, and the mixture was stirred for 30 minutes to prepare a magnetic paint. This magnetic paint was applied on a polyethylene terephthalate base having a thickness of 12 μm so that the thickness after drying was 3 μm, and a magnetic field orientation treatment was performed. Next, the magnetic coating film was dried and wound up. Then, after subjecting the magnetic coating film to a calendering treatment, a lubricant solution obtained by dissolving Compound 1 in n-hexane is applied on the magnetic coating film at an application amount of 50 mg / m ² , and cut into 8 mm width. To prepare a sample tape.

Examples 8 to 12 Sample tapes were prepared in the same manner as in Example 7, except that Compounds 2 to 6 were used as lubricants.

Comparative Example 3 A sample tape was prepared in the same manner as in Example 1 except that butyl stearate was used as a lubricant.

Comparative Example 4 Example 1 except that stearic acid was used as a lubricant.
A sample tape was produced in the same manner as described above.

The sample tape prepared as described above was aged at a temperature of 40 ° C. and a relative humidity of 80%, and the friction coefficient, stick slip and dropout were measured before and after the aging. Also,
After the dropout measurement, the occurrence of brown stain was examined. The results are shown in Tables 4 and 5. Table 4 shows the measurement results before aging, and Table 5 shows the measurement results after aging. The coefficient of friction was measured under the conditions described above. The methods for measuring stick-slip, drop-out and brown stain are as follows.

Stick slip: Judgment was made based on whether or not the coefficient of static friction with the stainless steel guide pin exceeded 0.6. When the coefficient of static friction exceeds 0.6, x;
The case of 6 or less was indicated by ○.

Dropout: 3 μs occurring in 3 minutes,
The evaluation was made by measuring the number of times the output decreased by 10 dB or more. The VCR used for the measurement was the same as that used for the evaluation of shuttle durability.

Brown Stain: Evaluation was made by visually observing the sliding surface of the magnetic recording medium of the magnetic head (metal-in-gap head having Fe-Si-Al disposed near the gap) after the dropout measurement. When the metal part was not stained, ○ was shown, when some stain was found, Δ was shown, and when the metal part was more than half dirty, × was shown. When the metal portion was contaminated by half or more, a level reduction of 5 dB or more was observed.

[0090]

[Table 4]

[0091]

[Table 5]

As can be seen from Tables 4 and 5, the sample tapes of Examples 7 to 12 using a fatty acid ester compound having a dialkylamino group and an aromatic ring as a lubricant have a coefficient of friction even after aging. It is kept low, and the occurrence of stick-slip and dropout is suppressed. Also, almost no brown stain is observed.

On the other hand, the sample tape of Comparative Example 3 in which butyl stearate was used as a lubricant and the sample tape of Comparative Example 4 in which stearic acid was used as a lubricant had a high coefficient of friction before aging, and had a drop. Outs occur frequently and brown stains are also observed. Aging further increases the coefficient of friction and worsens dropout and brown stain. Then, stick-slip also occurs.

From this, it was found that the fatty acid ester-based compound having a dialkylamino group and an aromatic ring was superior in lubricating performance as compared with other lubricants, and also excellent in removing brown stain.

[0095]

As is clear from the above description, since the lubricant of the present invention is a fatty acid ester compound having a dialkylamino group and an aromatic ring, it can be used under normal temperature and normal humidity, high temperature and high humidity. Good lubrication performance can be obtained even in a severe environment such as low temperature, and the effect of removing brown stain attached to the head is exhibited.

Further, in the magnetic recording medium of the present invention, since such a lubricant is held on the surface of the magnetic layer or the protective film, good running durability can be obtained and the level reduction due to brown stain can be suppressed. Can be.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing an infrared absorption spectrum of a synthesized fatty acid ester compound having a dialkylamino group and an aromatic ring.

Claims (5)

[Claims] 1. A lubricant characterized by being a fatty acid ester compound represented by the following chemical formula 1. Embedded image 2. A magnetic recording medium comprising at least a magnetic layer on a non-magnetic support, wherein the magnetic layer holds a fatty acid ester-based lubricant represented by Chemical Formula 2. Embedded image 3. The magnetic layer according to claim 2, wherein the fatty acid ester-based lubricant is top-coated on the surface of the magnetic layer.
The magnetic recording medium according to the above. 4. The magnetic recording medium according to claim 2, wherein the fatty acid ester-based lubricant is internally added to the magnetic layer. 5. The magnetic recording medium according to claim 2, wherein a protective film is formed on the magnetic layer, and the surface of the protective film is top-coated with the fatty acid ester-based lubricant.