JPH05194970A - Lubricant and magnetic recording medium coated therewith - Google Patents

Abstract

PURPOSE:To obtain a lubricant which can exhibit excellent lubricating properties under various conditions of use by esterifying a perfluoropolyether terminated with hydroxyl or like groups with a long-chain carboxylic acid or the like. CONSTITUTION:A lubricant comprising an ester of formula I or II (wherein R1 is a perfluoropolyether chain; and R alkyl or fluoroalkyl) which is a compound of a perfluoropolyether terminated with hydroxyl groups with a long-chain carboxylic acid. Alternatively, a lubricant comprising an ester of a perfluoropolyether terminated with carboxyl groups with a long-chain alcohol of formula III or IV (wherein R1 and R2 are as defined above). These lubricants can exhibit excellent lubricating properties under any condition of uses, can retain their effects for a long time, and can improve markebly the running properties and durability of the medium, when applied to the surface of a magnetic layer as lubricants.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant in a magnetic recording medium such as a magnetic tape or a magnetic disk and a magnetic recording medium using the same.

[0002]

2. Description of the Related Art For example, in a so-called metal magnetic thin film type magnetic recording medium in which a ferromagnetic metal material is deposited on the surface of a non-magnetic support by a technique such as vapor deposition and the magnetic layer is used as a magnetic layer, the surface of the magnetic layer is smoothed. Since it has extremely good properties, the substantial contact area with sliding members such as magnetic heads and guide rollers is large, and therefore the friction coefficient is large and the adhesion phenomenon (so-called sticking) is likely to occur and running performance and durability are lacking. There are many problems.

Therefore, use of various kinds of lubricants has been studied in order to improve these problems, and friction has been hitherto caused by top-coating a higher fatty acid or ester thereof on the magnetic layer of the magnetic recording medium. Attempts have been made to reduce the coefficient.

By the way, the lubricant used in the magnetic recording medium is required to have very strict characteristics, and it is difficult at present to deal with the conventional lubricant.

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. Since pacing becomes a problem, it is necessary 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 maintain the lubrication effect. To be done.

However, conventionally used higher fatty acids and esters thereof are frozen and solidified under low temperature conditions such as 0 ° C. or lower, impairing the function as a lubricant, and long-term durability. Tend to lack. Further, a method of using perfluoropolyethers as a lubricant has also been proposed, but perfluoropolyether is a material which is not always preferable in terms of environmental problems, etc., since it shows solubility only in a fluorocarbon solvent. I can't say that there is.

[0007]

As described above, in the field of magnetic recording media, practical properties such as running performance and durability are unsatisfactory due to lack of ability of the lubricant used. Therefore, the present invention is intended to provide a lubricant that exhibits excellent lubricity under various use conditions, and to provide a magnetic recording medium excellent in running property, wear resistance, durability, and the like. is there.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies as a means to achieve the above-mentioned object, and as a result, have found that a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid or a fluorinated alkyl group are used. By using an ester compound with a carboxylic acid having, or an ester compound of a perfluoropolyether having a carboxyl group at the terminal and an alcohol having a long-chain alcohol or a fluorinated alkyl group as a lubricant, an excellent lubricating effect can be obtained. The present invention has been completed and the present invention has been completed.

That is, the lubricant according to the first to fourth inventions of the present application is an ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid or a carboxylic acid having a fluorinated alkyl group, or a terminal compound. And a perfluoropolyether having a carboxyl group and an ester compound of a long-chain alcohol or an alcohol having a fluorinated alkyl group.

Further, the magnetic recording medium according to the fifth to eighth inventions of the present application is a magnetic recording medium having at least a magnetic layer on a non-magnetic support, wherein the surface of the magnetic layer has the above-mentioned first feature. The present invention is characterized by containing the lubricant according to the fourth invention.

The lubricant according to the first or second invention of the present application comprises an ester compound of a perfluoropolyether having a hydroxyl group or a carboxyl group at the terminal and a long-chain carboxylic acid or a long-chain alcohol. The lubricant according to the third to fourth inventions of the present application is an ester compound of a perfluoropolyether having a hydroxyl group or a carboxyl group at the terminal and a carboxylic acid having a fluorinated alkyl group or an alcohol having a fluorinated alkyl group. It consists of These ester compounds are
Alternatively, it exhibits excellent lubricity even when used under severe conditions such as high temperature and high humidity, and its effect is maintained for a long time.

Therefore, if these ester compounds are used as lubricants for magnetic recording media, the friction coefficient can be reduced due to the excellent lubrication effect, and the running property, abrasion resistance, durability, etc. can be greatly improved. it can. Further, since the above ester compound is soluble in organic solvents other than CFC-based solvents (for example, n-hexane and ethanol), it is possible to reduce the amount of CFC-based solvent used or eliminate it. It is also convenient in terms of problems.

First, in the first invention of the present application, the ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid is, for example, a catalyst of perfluoropolyether having a hydroxyl group at the terminal and a carboxylic acid chloride base. Is obtained by reacting as.

The perfluoropolyether having a hydroxyl group at the terminal used when synthesizing this ester compound may be one having a hydroxyl group at at least one terminal (one terminal) (monofunctional perfluoropolyether), Those having hydroxyl groups at both ends (polyfunctional perfluoropolyether) may be used and can be used regardless of the substitution position.

Specific examples include monofunctional perfluoropolyethers represented by the following formulas (1) and (2), and polyfunctional perfluoropolyethers include: Examples thereof include, but are not limited to, those represented by the formula (3).

[0016]

[Chemical 21]

However, in the above equations (1) to (3), p, q,
l, m, and n each represent an integer of 1 or more. The molecular weight of the perfluoropolyether having a hydroxyl group at its terminal is not particularly limited, but it is practically 6
It is preferably about 00 to 5000. If the molecular weight is too large, the effect of the terminal group as an adsorbing group is diminished, and at the same time, the amount of CFC used is increased due to the larger perfluoropolyether chain. On the other hand, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a hydroxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated. That is, a part (50% or less) of the fluorine atoms of the perfluoropolyether chain may be replaced with hydrogen atoms. In this case, a partially hydrogenated perfluoropolyether may be used as the perfluoropolyether, which makes it possible to reduce the amount of fluorocarbon solvent used.

On the other hand, as the carboxylic acid chloride base, either a commercially available product or a synthetic product can be used.

The thus synthesized ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid is represented by the following general formula (4) or (5). _{R f -CH 2 OCOR ··· (4} ) RCOOCH 2 -R f -CH 2 OCOR ··· (5) where (4) to (5), the R _f, the perfluoropolyether chain Represent R represents an alkyl group.

The long-chain carboxylic acid may have any structure such as a branched structure, an isomer structure, an alicyclic structure, or an unsaturated bond.
Further, the molecular weight is also arbitrary, but it is preferable that the alkyl group has at least 10 carbon atoms because it becomes difficult to dissolve in an organic solvent other than CFC as the molecular weight becomes smaller.

In the second invention of the present application, the ester compound of a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol may be, for example, a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol. For example, it is obtained by reacting in anhydrous toluene with p-toluenesulfonic acid or concentrated sulfuric acid as a catalyst.

The perfluoropolyether having a carboxyl group at the terminal used when synthesizing this ester compound may be a monofunctional perfluoropolyether or a polyfunctional perfluoropolyether, and its substitution position is It can be used independently.

Specific examples thereof include monofunctional perfluoropolyethers represented by the following formulas (6) to (7) and the like, and polyfunctional perfluoropolyethers include the following. Examples thereof include those represented by the formula (8), but are not limited thereto.

[0025]

[Chemical formula 22]

However, in the above equations (6) to (8), p, q,
l, m, and n each represent an integer of 1 or more. The molecular weight of the perfluoropolyether having a carboxyl group at its terminal is not particularly limited, but is practically preferably about 600 to 5,000. If the molecular weight is too large, the effect of the terminal group as an adsorbing group is diminished, and at the same time, the amount of CFC used is increased due to the larger perfluoropolyether chain. On the other hand, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a carboxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated as in the case of the first invention of the present application.

On the other hand, as the above long-chain alcohol, either a commercial product or a synthetic product can be used. Further, as the molecular weight becomes smaller, it becomes more difficult to dissolve in an organic solvent other than CFC, so that it is preferable that at least one of the alkyl groups has 6 or more carbon atoms.

The thus synthesized ester compound of a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol is represented by the following general formula (9) or (10). _Rf- COOR ... (9) ROOC- _Rf- COOR ... (10) However, in said Formula (9)-(10), _Rf represents a perfluoropolyether chain. R represents an alkyl group. The structure of the alkyl group R is arbitrary and can be selected regardless of the presence or absence of a branched structure, an isomer structure, an alicyclic structure and an unsaturated bond. Further, the molecular weight thereof is also optional, but in consideration of the solubility in organic solvents other than CFC, the carbon number is preferably 6 or more.

In the third invention of the present application, the ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a carboxylic acid having a fluorinated alkyl group is, for example, a perfluoropolyether having a hydroxyl group at the terminal (FR).
_f- CH ₂ OH or HOCH ₂ -R _f -CH ₂ OH) and a corresponding acid chloride derived from a carboxylic acid (RCOOH) having a fluoroalkyl group in an equimolar amount with the hydroxyl group contained in the perfluoropolyether. It is obtained by mixing with (RCOCl).

The synthetic reaction of this ester compound is represented by the following formula (11) or (12). FR _f -CH ₂ OH + RCOCl → FR _f -CH ₂ OCOR + HCl ・ ・ ・ (11) HOCH ₂ -R _f -CH ₂ OH + 2RCOCl → RCOOCH ₂ -R _f -CH ₂ OCOR + 2HCl ・ ・ ・ (12)

The perfluoropolyether having a hydroxyl group at the terminal used when synthesizing this ester compound may be a monofunctional perfluoropolyether or a polyfunctional perfluoropolyether, and depending on its substitution position. Can be used without.

As a specific example, as the monofunctional perfluoropolyether, the following (13) to (15)
Examples of the polyfunctional perfluoropolyether include those represented by the following formulas (16) to (18), but are not limited thereto.

[0034]

[Chemical formula 23]

However, in the above equations (13) to (18), i,
j, k, l, and m each represent an integer. The molecular weight of the perfluoropolyether having a hydroxyl group at its terminal is not particularly limited, but practically 600
It is preferably about 5,000. If the molecular weight is too large, the effect of the terminal group as an adsorbing group is diminished, and at the same time, the amount of CFC used is increased due to the larger perfluoropolyether chain. On the other hand, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a hydroxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated as in the case of the first invention of the present application.

On the other hand, as the carboxylic acid having a fluorinated alkyl group, one having a general formula represented by the following formula (19) is used. RCOOH (19) However, in the above formula (19), R represents a fluorinated alkyl group having 7 to 30 carbon atoms. Further, in the carboxylic acid having a fluorinated alkyl group, its structure and the like are arbitrary and can be selected regardless of the presence or absence of a branched structure, a cyclic group, an aromatic ring, or an unsaturated bond.

The ester compound of the perfluoropolyether having a carboxyl group at the terminal and the carboxylic acid having a fluorinated alkyl group synthesized as described above is represented by the following general formula (20) or (21). expressed. _{R f -CH 2 OCOR ··· (20} ) RCOOCH 2 -R f -CH 2 OCOR ··· (21) However, the above-mentioned (20) to (21), the R _f, the perfluoropolyether chain Represent R represents a fluorinated alkyl group.

Further, in the fourth invention of the present application, the ester compound of a perfluoropolyether having a carboxyl group at a terminal and an alcohol having a fluorinated alkyl group is, for example, a perfluoropolyether having a carboxyl group at a terminal (FR). _f -COOH or HOOC-R _f -COOH) corresponding acid chloride (FR _f -COCl or ClOC-R _f -C)
OCl 2) and an alcohol (ROH) having a fluorinated alkyl group in an equimolar amount with the carboxyl group contained in the perfluoropolyether.

The synthetic reaction of this ester compound is represented by the following formula (22) or (23). FR _f -COCl + ROH → FR _f -COOR + HCl ・ ・ ・ (22) ClOC-R _f -COCl ＋ 2ROH → ROOC -R _f -COOR ＋ 2HCl ・ ・ ・ (23)

The perfluoropolyether having a carboxyl group at the terminal used when synthesizing this ester compound may be a monofunctional perfluoropolyether or a polyfunctional perfluoropolyether, and at its substitution position. It can be used independently.

As a specific example, as the monofunctional perfluoropolyether, the following (24) to (26)
Examples of the polyfunctional perfluoropolyether include those represented by the following formulas (27) to (29), but the polyfunctional perfluoropolyethers are not limited thereto.

[0043]

[Chemical formula 24]

However, in the equations (24) to (29), i,
j, k, l, and m each represent an integer. The molecular weight of the perfluoropolyether having a carboxyl group at its terminal is not particularly limited, but is practically preferably about 600 to 5,000. If the molecular weight is too large, the effect of the end group as an adsorbing group is weakened, and at the same time,
The amount of CFC used increases as the perfluoropolyether chain becomes larger. On the other hand, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a carboxyl group at its terminal, the perfluoropolyether chain may be partially hydrogenated as in the case of the first invention of the present application.

On the other hand, as the alcohol having a fluorinated alkyl group, one having a general formula represented by the following formula (30) is used. ROH (30) However, in the above formula (30), R represents a fluorinated alkyl group having 7 to 30 carbon atoms. The structure of the alcohol having a fluorinated alkyl group is arbitrary and can be selected regardless of the presence or absence of a branched structure, a cyclic group, an aromatic ring, or an unsaturated bond.

The ester compound of the perfluoropolyether having a carboxyl group at the terminal and the alcohol having a fluorinated alkyl group synthesized in this manner is represented by the general formula shown in the following formula (31) or (32). To be done. _{R f -CH 2 OCOR ··· (31} ) RCOOCH 2 -R f -CH 2 OCOR ··· (32) However, the above-mentioned (31) to (32), the R _f, the perfluoropolyether chain Represent R represents a fluorinated alkyl group.

Further, the magnetic recording medium according to the fifth to eighth inventions of the present application has the above-mentioned ester compound according to the fifth to eighth inventions of the present application as a lubricant on the surface of the magnetic layer. ..

The magnetic recording medium to which the present invention is applied is not particularly limited, but in the present invention, a metal magnetic thin film as a magnetic layer is formed on the surface of a non-magnetic support by a method such as vapor deposition or sputtering. It is effective when applied to a so-called metal magnetic thin film type magnetic recording medium formed by deposition.
Of course, in the magnetic recording medium to which the present invention is applied, the film configuration and the like are arbitrary, and for example, an underlayer may be interposed between the non-magnetic support and the magnetic layer.

In this metal magnetic thin film type magnetic recording medium, the types of non-magnetic support, metal magnetic thin film and the like are not limited in any way, and any conventionally known one can be used. For example, as the non-magnetic support, for example, a polymer support formed of a plastic material represented by polyesters, polyolefins, cellulose derivatives, vinyl resins, polyimides, polyamides, polycarbonates, etc. Or aluminum alloy,
Any of a metal substrate made of titanium alloy or the like, a ceramic cook substrate made of alumina glass or the like, a glass substrate or the like can be used. Of these, when a rigid substrate such as an Al alloy plate or a glass plate is used, an oxide film such as an alumite treatment or a Ni-P film is formed on the substrate surface to harden the surface. Good.

The shape of the non-magnetic support is not limited to any particular shape, and may be any shape such as tape, sheet or drum. Furthermore, fine irregularities may be formed on the non-magnetic support in order to control its surface property.

The above-mentioned metal magnetic thin film is formed as a continuous film by a vacuum thin film forming technique such as plating, sputtering or vacuum deposition. For example, metals such as Fe, Co and Ni, Co--Ni type alloys and Co--Pt are used. Series alloy, Co-Pt-
Ni-based alloy, Fe-Co-based alloy, Fe-Ni-based alloy, F
e-Co-Ni system alloy, Fe-Ni-B system alloy, Fe-
It is possible to use an in-plane magnetization recording metal magnetic film or a Co-Cr alloy thin film made of a Co-B alloy, an Fe-Co-Ni-B alloy, or 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, Ti is formed in advance, and a magnetic metal 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 anti-magnetism may be improved.

When a rigid substrate (hard disk) is used as a constituent material of the non-magnetic support as described above, for example, a carbon film, a diamond-like or amorphous carbon film is formed on the surface of the metal magnetic thin film. A hard protective film such as a chromium oxide film or a SiO ₂ film may be formed.

In such a magnetic recording medium, the above-mentioned first
Through a method of retaining the lubricant of the fourth invention,
A method of top-coating a lubricant layer on the surface of the magnetic layer formed of the metal magnetic thin film or the like or the surface of the protective film may be mentioned. In this case, the applied amount of lubricant used is
It is preferably 0.5 to 100 mg / m ² , and
It is more preferably 20 mg / m ² .

The ester compound used as a lubricant in the present invention may be used alone as a lubricant for a magnetic recording medium, or may be used in combination with a conventionally known lubricant.

Further, an extreme pressure agent may be used in combination in a weight ratio of about 30:70 to 70:30 in order to cope with more severe conditions and maintain the lubricating effect. This extreme pressure agent
When a metal contact is partially generated in the boundary lubrication region, frictional heat associated with the metal contact reacts with the metal surface to form a reaction product film, thereby performing a friction and wear preventing action. Any of an extreme pressure agent, a sulfur type extreme pressure agent, a halogen type extreme pressure agent, an organometallic type extreme pressure agent, a composite type extreme pressure agent and the like can be used.

In the magnetic recording medium of the present invention,
In addition to the above-mentioned lubricant and extreme pressure agent, a rust preventive agent may be used in combination, 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.

By the way, in the above-mentioned magnetic recording medium of the metal magnetic thin film type, a back coat layer, an undercoat layer and the like may be formed, if necessary, in addition to the metal magnetic thin film which is the magnetic layer.

For example, the back coat layer controls the carbon-based fine powder for imparting conductivity and the surface roughness to the resin binder similar to the magnetic coating film used in the so-called coating type magnetic recording medium. Add an inorganic pigment for
Although it is obtained by coating and forming this, in the present invention, a lubricant comprising the above ester compound may be internally added or contained in the back coat layer by a top coat.

Further, in the present invention, a lubricant comprising the above ester compound may be internally added to or top coated on the magnetic coating film, the metal magnetic thin film, the back coat layer and the like, and various combinations are possible. is there.

[0062]

[Function] An ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid or a carboxylic acid having a fluorinated alkyl group, a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol or fluorinated alkyl Lubricants composed of ester compounds with group-containing alcohols have good lubricity, and exhibit this effect even under severe conditions such as low temperature and low humidity, or high temperature and high humidity, and in the long term. Lubricity does not decrease over time.

Therefore, in the magnetic recording medium, by retaining the lubricant on the surface of the magnetic layer, the friction coefficient is reduced by the excellent lubrication effect of the lubricant,
Driving performance and durability are improved.

[0064]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples. -Experiment 1-In this experiment, a so-called metal magnetic thin film is used in which an ester compound of perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid is used as a lubricant, and the lubricant is applied to the surface of the magnetic layer. The type magnetic tape was examined for durability and runnability under various usage conditions.

Synthesis of Ester Compound First, HOCH ₂ CF ₂ (OC ₂ F ₄ ) p (OCF ₂ ) qOCF ₂ C having a molecular weight of 2000 was obtained as a perfluoropolyether having a hydroxyl group at the terminal.
H ₂ OH (provided that p and q each represent an integer of 1 or more) was dissolved in perfluoropolyether and triethylamine in a molar ratio of 2 times, and the moles thereof were added to the solution. Two times the equivalent amount of stearic acid chloride was added dropwise over 30 minutes.

After completion of dropping, the mixture was stirred for 1 hour and then heated and refluxed for 30 minutes. Then, after cooling, it was washed with distilled water and a dilute hydrochloric acid aqueous solution in this order, and again with distilled water until the washing liquid became neutral. Then, the organic solvent was removed, and the obtained compound was purified by silica gel column chromatography.

Here, the infrared absorption spectrum of the purified compound 1 was examined. The result is shown in FIG. As shown in FIG. 1, along with stretching vibration of C-H bonds appears at 2920 cm ^-1 and 2850 cm ^-1, stretching vibration of the carbonyl group 1765Cm ^-1, and from 1350 cm ^-1 1000
Stretching vibrations of the C—F bond appear over cm ⁻¹ ,
On the other hand, since the absorption derived from the hydroxyl group near 3690 cm ^-1 has disappeared, this compound 1 was used as stearic acid ester of perfluoropolyether C ₁₇ H ₃₅ COOCH ₂ CF ₂ (OC ₂ F ₄ ).
p (OCF ₂ ) qOCF ₂ CH ₂ OOCC ₁₇ H ₃₅ (provided that p and q each represent an integer of 1 or more).

Next, in the same manner as in the above-mentioned compound 1, various ester compounds (compounds 2 to 14) of perfluoropolyether having hydroxyl groups at both ends and a long-chain carboxylic acid as shown in the following Table 1 were prepared. Synthesized. In addition, in Table 1,
p, q, l, m, and n each represent an integer of 1 or more.

[0069]

[Table 1]

Compounds 1 to 1 synthesized as described above
Using 4 as a lubricant, 14 types of sample tapes were prepared according to the following procedure.

Preparation of Sample Tape Co was adhered to a 14 μm thick polyethylene terephthalate film by the oblique evaporation method to form a metal magnetic thin film having a film thickness of 100 nm. Next, compounds 1 to 14 shown in Table 1 above were dissolved in a mixed solvent of freon and ethanol, and the coating amount was 5 mg / m ^{2 on} the surface of the metal magnetic thin film.
Was applied so that

Then, the obtained magnetic tape was cut into 8 mm width to obtain sample tapes 1 to 14.

Evaluation of Durability and Runnability Each of the sample tapes 1 to 14 produced as described above
The friction coefficient, the still durability and the shuttle durability were measured under various operating conditions at a temperature of 25 ° C. and a humidity of 60%, a temperature of −5 ° C. and a temperature of 40 ° C. and a humidity of 30%. For comparison, a blank tape containing no lubricant (referred to as Comparative Example 1) and a perfluoropolyether having a hydroxyl group at the end shown in Table 2 below as a lubricant (in Table 2, p , Q, l, m, n is 1
Each of the above integers is represented. ) Was also used for sample tapes (Comparative Examples 2 to 4) used alone. The results are shown in Tables 3 to 5 below.

In Tables 3 to 5, the still durability represents the time required for the output to decrease by 3 dB in the pause state, and the shuttle durability represents the shuttle running time of 2 minutes at a time. It represents the number of shuttles until the output drops by 3 dB.

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

[Table 4]

[0078]

[Table 5]

As shown in Tables 3 to 5, as compared with the case where a perfluoropolyether having a hydroxyl group at the terminal was used alone as a lubricant, when it was used as an ester compound with a long-chain carboxylic acid, Even under various usage conditions such as high humidity or low temperature and low humidity, the friction coefficient, still durability, and shuttle durability were extremely little deteriorated, and very good results were obtained.

Experiment 2-In this experiment, an ester compound of a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol is used as a lubricant, and this lubricant is applied to the surface of the magnetic layer. About magnetic tape of metal magnetic thin film type,
The durability and running property under various usage conditions were examined.

Synthesis of Ester Compound First, HOOCCF ₂ (OC ₂ F ₄ ) p (OC having a molecular weight of 2000 was obtained as a perfluoropolyether having a carboxyl group at the terminal.
F ₂ ) qOCF ₂ C0OH (provided that p and q each represent an integer of 1 or more), and a 2-fold equimolar amount of stearyl alcohol in molar ratio with this perfluoropolyether was used in anhydrous toluene. -Toluenesulfonic acid and concentrated sulfuric acid were used as catalysts and heated to reflux. At this time, it was performed while removing the generated water.

After completion of the reaction, toluene was removed, and the obtained compound was purified by silica gel column chromatography.

Here, the infrared absorption spectrum of the purified compound 15 was examined. The result is shown in FIG. As shown in FIG. 2, C-H at 2920 cm ^-1 and 2850 cm ^-1
With bond stretching vibration appears, stretching vibration of the carbonyl group of 1760 cm ^-1 is moved to 1790 cm ^-1, also appear stretching vibration of C-F bonds, each over a period of from 1300 cm ^-1 to 1060 cm ^-1, whereas 3600cm around ^-1 Since the absorption derived from the hydroxyl group of the compound has disappeared, this compound 15 was used as a stearic acid ester of perfluoropolyether C ₁₇ H ₃₅ OOCCF ₂ (OC ₂ F ₄ ) p (OCF ₂ ) qOCF ₂ COOC ₁₇ H ₃₅ ( However, p and q each represent an integer of 1 or more).

Next, various ester compounds (compounds 16 to 28) of perfluoropolyether having carboxyl groups at both ends and long chain alcohols (compounds 16 to 28) as shown in Table 6 below were prepared in the same manner as in the above compound 15. Synthesized. In Table 6, p, q, l, m, and n each represent an integer of 1 or more.

[0085]

[Table 6]

Preparation of Sample Tapes Various sample tapes 15 to 28 were prepared in the same manner as in Experiment 1 except that the compounds 15 to 28 synthesized as described above were used as lubricants.

Evaluation of Durability and Runnability Each of the sample tapes 15 to 2 produced as described above
8, the friction coefficient, the still durability, and the shuttle durability were measured under various operating conditions in the same manner as in Experiment 1 above. For comparison, a blank tape containing no lubricant (referred to as Comparative Example 5) and a perfluoropolyether having a carboxyl group at the terminal shown in Table 7 below as a lubricant (in Table 7, p, q, l, m, n
Each represents an integer of 1 or more. ) Was used alone, and the sample tapes (Comparative Examples 6 to 8) were similarly measured. The results are shown in Tables 8 to 10 below.

[0088]

[Table 7]

[0089]

[Table 8]

[0090]

[Table 9]

[0091]

[Table 10]

As shown in Tables 8 to 10, as compared with the case where a perfluoropolyether having a carboxyl group at the terminal was used alone as a lubricant, the temperature was higher when used as an ester compound with a long chain alcohol. Even under various usage conditions such as high humidity or low temperature and low humidity, deterioration of friction coefficient, still durability, shuttle durability is extremely low,
Very good results have been obtained.

-Experiment 3-In this experiment, an ester compound of perfluoropolyether having a hydroxyl group at the terminal and a carboxylic acid having a fluorinated alkyl group was used as a lubricant, and this lubricant was applied to the surface of the magnetic layer. The so-called metal magnetic thin film type magnetic tape thus obtained was examined for durability and running property under various usage conditions.

Synthesis of Ester Compound First, a perfluoropolyether having a hydroxyl group at the terminal and a corresponding acid chloride derived from a carboxylic acid having a fluoroalkyl group in an equimolar amount with the hydroxyl group contained in the perfluoropolyether. Table 11 below
To various ester compounds (compounds 29 to 3)
8) was synthesized. In Table 11, l, m, and n each represent a positive integer.

[0095]

[Table 11]

Preparation of Sample Tapes Various sample tapes 29 to 38 were prepared in the same manner as in Experiment 1 except that the compounds 29 to 38 synthesized as described above were used as lubricants.

Evaluation of Durability and Runnability Each of the sample tapes 29 to 3 produced as described above
8, the friction coefficient, the still durability, and the shuttle durability were measured under various operating conditions in the same manner as in Experiment 1 above. For comparison, a blank tape containing no lubricant (referred to as Comparative Example 9) was similarly measured. The results are shown in Table 12 below.

[0098]

[Table 12]

As shown in Table 12, by using an ester compound of a perfluoropolyether having a hydroxyl group at the terminal and a carboxylic acid having a fluorinated alkyl group as a lubricant, the friction coefficient, the still durability and the shuttle durability were obtained. As for the properties, very good results were obtained without deterioration under various conditions.

-Experiment 4-In this experiment, an ester compound of perfluoropolyether having a carboxyl group at the terminal and alcohol having a fluorinated alkyl group was used as a lubricant, and this lubricant was applied to the surface of the magnetic layer. The so-called metal magnetic thin film type magnetic tape thus obtained was examined for durability and running property under various usage conditions.

Synthesis of Ester Compound First, a corresponding acid chloride derived from a perfluoropolyether having a carboxyl group at the terminal and an alcohol having a fluoroalkyl group in an equimolar amount to the carboxyl group contained in this perfluoropolyether. And were mixed to synthesize various ester compounds (Compounds 39 to 48) as shown in Table 13 below. In addition, in Table 13,
l, m, and n each represent a positive integer.

[0102]

[Table 13]

Preparation of Sample Tapes Various sample tapes 39 to 48 were prepared in the same manner as in Experiment 1 except that the compounds 39 to 48 synthesized as described above were used as lubricants.

Evaluation of Durability and Runnability Each of the sample tapes 39 to 4 produced as described above
8, the friction coefficient, the still durability, and the shuttle durability were measured under various operating conditions in the same manner as in Experiment 1 above. For comparison, a blank tape containing no lubricant (referred to as Comparative Example 10) was also measured in the same manner. The results are shown in Table 14 below.

[0105]

[Table 14]

As shown in Table 14, by using an ester compound of a perfluoropolyether having a carboxyl group at the terminal and an alcohol having a fluorinated alkyl group as a lubricant, the friction coefficient, the still durability, and the shuttle durability were obtained. As for the properties, very good results were obtained without deterioration under various conditions.

[0107]

As is apparent from the above description, in the present invention, a perfluoropolyether having a hydroxyl group or a carboxyl group at the terminal and a long-chain carboxylic acid or a long-chain alcohol, which have extremely excellent lubricity, Alternatively, since an ester compound with a carboxylic acid or alcohol having a fluorinated alkyl group is used as a lubricant, excellent lubricity can be exhibited under any conditions of use, and the effect is maintained over a long period of time. can do. Therefore, if the ester compound is retained as a lubricant in the magnetic recording medium on the surface of the magnetic layer, the running property and durability can be significantly improved.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing an infrared absorption spectrum of an example of a lubricant to which the present invention is applied.

FIG. 2 is a characteristic diagram showing an infrared absorption spectrum of another example of the lubricant to which the present invention is applied.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Koichi Tanaka 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (12)

[Claims] 1. A lubricant comprising a compound of a perfluoropolyether having a hydroxyl group at the terminal and a long-chain carboxylic acid, and comprising an ester compound represented by the following chemical formula 1 or chemical formula 2. [Chemical 1] [Chemical 2] 2. A compound of a perfluoropolyether having a carboxyl group at the terminal and a long-chain alcohol,
A lubricant comprising an ester compound represented by the following chemical formula 3 or chemical formula 4. [Chemical 3] [Chemical 4] 3. A compound of a perfluoropolyether having a hydroxyl group at the terminal and a carboxylic acid having a fluorinated alkyl group represented by the following Chemical formula 5, which is represented by the following Chemical formula 6 or Chemical formula 7
A lubricant comprising an ester compound represented by: [Chemical 5] [Chemical 6] [Chemical 7] 4. A compound of a perfluoropolyether having a carboxyl group at a terminal and an alcohol having a fluorinated alkyl group represented by the following chemical formula 8, which is represented by the following chemical formula 9.
Alternatively, a lubricant comprising an ester compound represented by Chemical formula 10. [Chemical 8] [Chemical 9] [Chemical 10] 5. A magnetic recording medium having at least a magnetic layer on a non-magnetic support, which is a compound of a perfluoropolyether having a hydroxyl group at the terminal on the surface of the magnetic layer and a long-chain carboxylic acid, A magnetic recording medium containing a lubricant comprising an ester compound represented by the following chemical formula 11 or chemical formula 12. [Chemical 11] [Chemical 12] 6. The surface of the magnetic layer is coated with 0.5 to 1 of the lubricant.
The magnetic recording medium according to claim 5, wherein the magnetic recording medium is applied at a rate of 00 mg / m ² . 7. A magnetic recording medium having at least a magnetic layer on a non-magnetic support, which is a compound of a long-chain alcohol and a perfluoropolyether having a terminal carboxyl group on the surface of the magnetic layer, A magnetic recording medium containing a lubricant comprising an ester compound represented by the following Chemical formula 13 or Chemical formula 14: [Chemical 13] [Chemical 14] 8. The surface of the magnetic layer is coated with 0.5 to 1 of the lubricant.
The magnetic recording medium according to claim 7, wherein the magnetic recording medium is applied at a rate of 00 mg / m ² . 9. A magnetic recording medium comprising at least a magnetic layer on a non-magnetic support, wherein the surface of the magnetic layer is a perfluoropolyether having a terminal hydroxyl group and an alkyl fluoride represented by the following chemical formula 15. A compound with a carboxylic acid having a group,
Alternatively, a magnetic recording medium containing a lubricant comprising an ester compound represented by Chemical formula 17 is provided. [Chemical 15] [Chemical 16] [Chemical 17] 10. The lubricant is applied to the surface of the magnetic layer in an amount of 0.5 to 0.5.
The magnetic recording medium according to claim 10, wherein the magnetic recording medium is applied at a rate of 100 mg / m ² . 11. A magnetic recording medium comprising at least a magnetic layer on a non-magnetic support, wherein a perfluoropolyether having a terminal carboxyl group on the surface of the magnetic layer and a fluorinated compound represented by the following chemical formula 18: A magnetic recording medium, which is a compound with an alcohol having an alkyl group and which holds a lubricant composed of an ester compound represented by the following Chemical formula 19 or Chemical formula 20. [Chemical 18] [Chemical 19] [Chemical 20] 12. The surface of the magnetic layer is coated with 0.5 to 0.5 of the lubricant.
The magnetic recording medium according to claim 11, wherein the magnetic recording medium is applied at a rate of 100 mg / m ² .