JP2000282074A - Lubricant, magnetic recording medium and production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant useful for producing a magnetic recording medium having excellent durability, abrasion resistance and practical reliability without impairing electromagnetic transducing properties by making the lubricant include a specific fluoropolyether-based compound. SOLUTION: This lubricant contains a fluoropolyether-based compound formula I (Ra is a perfluoroalkyl or a perfluoroalkenyl; Xa is a perfluoropolyether chain or the like; Za is F or a polar group; f is an integer of >=1; g is an integer of >=0), a fluoropolyether-based compound of formula II (Xb is a straight-chain perfluoropolyether chain containing one or more kinds of perfluoroalkylene oxide groups as a structural unit; Zb1 and Zb2 are each a polar group; i is an integer of >=1; h and j are each an integer of >=0) or a fluoropolyether-based compound containing >=3 repeating units of formula III (Rc is F or the like; Xc is a perfluoropolyether chain or the like; Zc is a polar group; u is an integer of >=0). Preferably a magnetic recording medium is prepared by using a lubricant-containing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant used for precision equipment or precision parts requiring a high degree of lubrication, and a magnetic recording exhibiting excellent lubrication properties for digital video tape recorders and hard disk drives. The present invention relates to a medium and a method for manufacturing the medium.

[0002]

2. Description of the Related Art In recent years, in the field of magnetic recording, with the advancement of digitalization, miniaturization, and prolonged use time of recording / reproducing devices, development of high-density magnetic recording media suitable therefor has been required. The metal thin-film magnetic recording medium, which is extremely advantageous for short-wavelength recording, has recently been put to practical use in place of the coating-type magnetic recording medium. In general, a metal thin film type magnetic recording medium refers to a tape, a disk, or the like in which a magnetic layer made of a ferromagnetic metal thin film is provided as a recording layer on a nonmagnetic substrate. In addition, recording of high-density magnetic recording media
Examples of the magnetic recording medium system used for reproduction include a digital video deck and a hard disk drive.

In a metal thin film type magnetic recording medium represented by a digital video tape, the magnetic layer has an extremely good surface property, that is, the magnetic layer has a small surface roughness, so that the contact area with the magnetic head is small. As a result, a large frictional force is applied during high-speed sliding with the magnetic head in the process of recording and reproducing a signal, so that the magnetic head is easily worn. The wear of the magnetic layer is
Since it greatly affects the running durability or still durability of the magnetic recording medium, reducing it is a major issue in research and development of a metal thin film magnetic recording medium.

[0004] Attempts have been made to reduce wear by providing a lubricant layer on the surface of the magnetic layer to improve running durability and still durability. In the case of providing a lubricant layer, in order to minimize output decrease due to spacing loss between the magnetic recording medium and the magnetic head and to increase output,
The lubricant layer on the surface of the magnetic layer is required to exhibit lubricating properties with a thickness of only a few nm.

[0005] In a general hard disk drive, a CSS (contact start / stop) system is adopted. In the CSS method, when the hard disk, which is a high-density magnetic recording medium, is stopped, the magnetic head contacts the disk, and when the hard disk starts rotating at high speed at start-up, the airflow generated by the magnetic head causes the magnetic head to rotate. In this method, recording / reproducing is performed while floating from the disk surface. When the disk stops, the rotation of the disk is reduced, and the magnetic head comes into contact with the hard disk again.

In the CSS system, the magnetic head runs by rubbing the surface of the hard disk when the operation of the disk is stopped or started, so that the frictional force applied at that time is a serious problem. In order to maintain the reliability of the hard disk drive, it is desired that the friction coefficient of the medium after the CSS running test is the same as that of the initial stage. However, for a magnetic disk with a high surface flatness, that is, a small roughness, this reliability is secured. Difficult to do. Another problem to be solved is the so-called head crash, in which the head collides with the medium when the hard disk is rotating at a high speed. One of the causes of the head crash is that the magnetic recording medium does not have an appropriate carbon film and lubricant layer.

Further, with the increase in recording density, it is necessary to consider a new technology such as mounting of an MR head and a GMR head and adoption of a contact recording method. It is necessary to further improve the characteristics.

Therefore, lubricant materials suitable for magnetic recording media have been widely studied. One of them is a fluorine compound. Since fluorine compounds show excellent lubrication properties,
The use of various compounds has been proposed, and among them, perfluoropolyether is widely used because it is superior in lubricating performance and surface protective action to other fluorine-based compounds. Perfluoropolyether can be used as an excellent lubricant because, due to the presence of an oxygen-containing ether bond in the molecule, its viscosity is lower than that of fluoroalkanes of the same molecular weight and a wide temperature range. And the viscosity characteristics do not change in the region. In addition, perfluoropolyethers are less reactive and chemically inert, have lower vapor pressure, higher thermal stability,
It has excellent chemical resistance, high chemical stability, low surface energy, and high water repellency, all of which are advantageous for use as a lubricant.

[0009] For example, in addition to a magnetic recording medium having a commercially available perfluoropolyether having a polar group as a lubricant layer, a commercially available ester derivative of perfluoropolyether is synthesized, and a compound obtained by purifying the ester derivative is used as a lubricant. A magnetic recording medium as a layer (see JP-A-9-291296);
Also, a magnetic recording medium using a perfluoropolyether-based lubricant purified using a good solvent and a poor solvent (see Japanese Patent No. 2677074) has been proposed or put into practical use.

[0010]

The properties of perfluoropolyether depend on its molecular structure. Currently, several types of perfluoropolyethers are commercially available, but they differ in molecular weight, main chain repeat units and / or end groups.

Commercially available perfluoropolyethers include, for example, Fomblin Z type and Fo type manufactured by Ausimont.
There is a mblin Y type, a Krytox type by Du-Pont, and a Demnum type by Daikin Industries. These commercially available perfluoropolyethers include a nonpolar type and a type having a polar group.When used as a lubricant, a perfluoropolyether having a polar group such as a hydroxyl group, a carboxyl group, an ester, or a piperonyl group is used. This has the advantage of increasing the adsorbing power of the lubricant layer on the carbon film.

Examples of perfluoropolyethers having a polar group include trade names Fomblin Z Dol (having a hydroxyl group as a polar group), Fomblin Z Diac (having a carboxyl group as a polar group), and Fomblin AM2001 (having a polar group) manufactured by Ausimont. And a product name of Demnum SA (having a hydroxyl group as a polar group) and Demnum SH (having a carboxyl group as a polar group) manufactured by Daikin Industries, Ltd. The molecular weight of these commercially available perfluoropolyethers is usually from 1,000 to 20,000
Within the range.

The difference in the molecular structure of these commercially available perfluoropolyethers is due to the difference in the synthesis method. Ausimont's Fomblin Z type reacts oxygen at −40 ° C. under ultraviolet irradiation on tetrafluoroethylene to form an unstable polyether containing peroxide,
This is obtained by heating and further treating with fluorine gas to decompose and synthesize peroxy bonds. Also, Fomblin Y
The type is obtained by using hexafluoropropylene instead of tetrafluoroethylene and synthesizing it by the same means as for the Z type. Krytox type manufactured by Du-Pont is obtained by ring-opening polymerization of hexafluoropropylene oxide with a fluorine ion catalyst to synthesize an oligomer having a polymerization degree of 2 to 50. Demnum type manufactured by Daikin Industries
It is obtained by fluorinating an oligomer obtained by ring-opening polymerization of 2,2,3,3-tetrafluorooxetane with a fluorinated ion catalyst with a fluorine gas and substituting and synthesizing a perfluoro compound.

A perfluoropolyether having a polar group can be obtained by modifying the terminal group to an acid halide, a carboxylic acid, or an alcohol using these various polyethers as starting materials.

As described above, since the commercially available perfluoropolyether is formed by polymerizing a predetermined fluoromonomer, its molecular structure is extremely limited. Although it is possible to carry out polymerization by changing the type of fluoromonomer molecule to obtain a perfluoropolyether having a desired molecular structure, it is often difficult to obtain a fluoromonomer molecule as a starting material in many cases. In some cases, the polymerization reaction does not proceed as expected. Therefore, it is generally extremely difficult to synthesize a fluoropolyether or perfluoropolyether having an arbitrary molecular structure, and therefore, such a compound has properties useful as a lubricant for forming a lubricant layer of a magnetic recording medium. I could not predict at all whether to show.

Further, commercially available perfluoropolyethers are formed by polymerization of monomer molecules, and therefore there are oligomers or polymers having different degrees of polymerization, and their molecular weights are not constant. Thus, a single molecular weight perfluoropolyether having the desired molecular weight or molecular structure,
Alternatively, a purification or distillation step is required to obtain a perfluoropolyether having a small molecular weight distribution. In particular, when introducing a polar group into perfluoropolyether,
The reaction yield is not always good, and unreacted impurities (perfluoropolyethers into which a predetermined amount of polar group has not been introduced) are often mixed in the product. Since such unreacted impurities cause deterioration of properties as a lubricant,
It is desirable to remove them. Therefore, as a method for purifying commercially available perfluoropolyether, a physical method such as distillation, a chemical method of extracting with a solvent, or a method using column chromatography using a column have been attempted. However, it is not appropriate considering efficiency and industrial efficiency.

As described above, a perfluoropolyether having a predetermined molecular structure is produced by polymerization of fluoromonomer molecules, and only a perfluoropolyether having a predetermined molecular weight or a predetermined molecular weight is obtained from commercially available perfluoropolyether. Is difficult to separate or purify.

In view of the above problems, the present invention provides a lubricating agent having a molecular structure different from that of a commercially available lubricant made of perfluoropolyether or a lubricant obtained by purifying a commercially available pofluoropolyether by a conventional method. By obtaining a fluoropolyether compound suitable for the agent by a specific method, and using this as a lubricant for a magnetic recording medium in particular,
It is an object of the present invention to provide a magnetic recording medium having excellent durability, lubricity, abrasion resistance and high practical reliability without impairing electromagnetic conversion characteristics, and to provide a method for manufacturing such a magnetic recording medium. I do.

[0019]

In order to solve the above problems, the lubricant of the present invention has the following general formulas (A) to (C):

Embedded image Wherein R ^a is a perfluoroalkyl group or a perfluoroalkenyl group, and X ^a is a linear perfluoroether chain or a perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit. Z ^a is a fluorine atom or a polar group, f is an integer of 1 or more, and g is an integer of 0 or more);

Embedded image (Wherein X ^b is a linear perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit, Z ^b1 and Z ^b2 are polar groups, and i is an integer of 1 or more. And h and j are integers greater than or equal to 0); or

Embedded image (Wherein, R ^c is a fluorine atom or a perfluoroalkyl group, X ^c is a linear perfluoroether chain or a perfluoropolyether chain, Z ^c is a polar group, and u is an integer of 0 or more. Which is a fluoropolyether compound represented by the formula:

In the compounds represented by the above general formulas,
By changing the type of perfluoroalkyl group or perfluoroalkenyl group, the type, number and arrangement of perfluoroalkylene oxide groups, the number of methylene groups, and / or the type of polar group, a conventional fluoropolyether is obtained. A fluoropolyether compound having a different molecular structure can be arbitrarily designed, and as a result, a lubricant exhibiting superior lubricating performance as compared with the case of using a conventional fluoropolyether compound can be obtained.

Such a perfluoropolyether compound having an arbitrary molecular structure is obtained not by polymerization of fluoromonomer molecules but by scavenging a hydrocarbon polyether compound having a predetermined main skeleton with hydrogen fluoride. It is manufactured by a manufacturing method including a step of fluorinating in the presence of an agent. Since a compound already in the form of a predetermined polyether is fluorinated, a fluoropolyether compound having a desired molecular structure can be surely obtained, and a compound obtained as compared with a case where a monomer is polymerized can be obtained. The purity is extremely high.

The lubricant of the present invention may further contain a fluorinated alkyl carboxylic acid monoester and / or a perfluoropolyether alkyl carboxylic acid diester.

The fluorinated alkyl carboxylic acid monoester has, for example, the following general formula (E):

Embedded image (Wherein, R ³ represents an alkyl group or an alkenyl group;
R ⁴ represents a fluoroalkyl group or a fluoroether group or a fluoropolyether group, and x is 0 or 1
And y is an integer of 0 to 20).

The perfluoropolyether alkyl carboxylic acid diester is, for example, represented by the following general formula (I):

Embedded image (Wherein, X is —OCOR ⁶ , wherein R ⁶ represents an alkyl group or an alkenyl group, r and s are integers of 1 or more, and t is an integer of 0 to 12). It is preferably at least one compound selected from the compounds.

The lubricant of the present invention is, for example, a magnetic recording medium in which a ferromagnetic metal thin film, a carbon film and a lubricant layer are formed in this order on a non-magnetic support (hereinafter simply referred to as a metal thin film type magnetic recording medium). When it is contained in the lubricant layer (which may be referred to as a recording medium), excellent lubrication properties are imparted to the magnetic recording medium, and a magnetic recording medium with high practical reliability is obtained.

The lubricant of the present invention may further contain at least one kind of an organic phosphorus compound. The organophosphorus compound acts as a rust inhibitor and / or an extreme pressure agent. For example, when this lubricant is contained in the lubricant layer of a magnetic recording medium, a gap between the lubricant layer and the carbon film is formed. Since it also plays a role of improving the adhesion strength of the magnetic recording medium, it is possible to further improve the lubrication performance and durability of the magnetic recording medium, and the practical reliability of the magnetic recording medium is further improved.

In the present invention, general formulas (J), (K),
(L), (M), (N), (O), (P), (Q), and (R):

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image (In the above general formulas (J) to (R), n is 8 to 20)
It is preferable to use an organic phosphorus compound selected from the group consisting of organic phosphorus compounds represented by the following formula:

When a lubricant layer of a metal thin-film magnetic recording medium is formed with a lubricant composition containing these specific organic phosphorus compounds, for example, the practical reliability of the magnetic recording medium is further improved.

The magnetic recording medium of the present invention is a magnetic recording medium comprising a ferromagnetic metal thin film provided on a non-magnetic support, and a lubricant layer provided on the ferromagnetic metal thin film via a carbon film. The lubricant layer is characterized by containing at least one kind of the lubricant of the present invention. According to this magnetic recording medium, the adhesion strength of the lubricant layer to the carbon film is improved,
In addition, good lubricating performance is obtained, and the synergistic effect improves practical reliability such as lubricity and durability without impairing electromagnetic conversion characteristics.

The method of manufacturing a magnetic recording medium according to the present invention is characterized by forming a lubricant layer. Other manufacturing steps may be steps conventionally used for manufacturing a magnetic recording medium. The step of forming a lubricant layer in the production method of the present invention includes applying a coating solution prepared by dissolving the above-mentioned lubricant in a mixed organic solvent of an alcohol solvent and a hydrocarbon solvent onto a carbon film, The method includes a step of drying the solvent. By using a mixed organic solvent of an alcohol-based solvent and a hydrocarbon-based solvent, a uniform thin lubricant layer with very little coating unevenness can be formed. Therefore, according to the manufacturing method of the present invention, it is possible to obtain a magnetic recording medium with high practical reliability.

In the above production method of the present invention, the mixing ratio of the alcohol solvent and the hydrocarbon solvent is 1: 1:
It is preferably in the range of 9 to 9: 1. Mixing both in this range makes it possible to minimize coating unevenness and is advantageous in terms of cost.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described, but the present invention is not limited thereto.

The first embodiment of the fluoropolyether compound contained in the lubricant of the present invention has the general formula (A):

Embedded image Wherein R ^a is a perfluoroalkyl group or a perfluoroalkenyl group, and X ^a is a linear perfluoroether chain or a perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit. And ^Za is a fluorine atom or a polar group, f is an integer of 1 or more, and g is an integer of 0 or more).

In the general formula (A), ^Ra is a perfluoroalkyl group or a perfluoroalkenyl group. The number of carbon atoms constituting ^Ra is preferably 1 to 12, more preferably 1 to 8.

X ^a is a linear perfluoroether chain or a perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit.
In the present specification, a perfluoroalkylene oxide group (that is, an oxyfluoroalkylene group) is-
_{(C w F 2 w O)} - (w is an integer of 1 or more) means a group represented by the. In formula (A), perfluoro alkylene oxide group constituting the X ^a is at least one. When there is one perfluoroalkylene oxide group, X ^a forms one ether bond,
In that case, ^Xa is referred to as a perfluoroether chain for convenience. If X ^a is composed of one perfluoro alkylene oxide group, to form a polyether having two ether linkages with the adjacent oxygen atom.

X ^a may be a perfluoropolyether chain having one type of perfluoroalkylene oxide group as a structural unit. That is, Xa ^is- ( _{CwF
2 w} O) - it may be comprised of having multiple repeating units one group represented by. In this case, the number of carbon atoms (corresponding to w) of the perfluoroalkylene oxide group is preferably from 1 to 7, and more preferably from 2 to 4, from the viewpoint of lubrication performance and stability of the compound.
When the number of carbon atoms is large, the number of ether bonds is smaller than that of a compound having the same molecular weight, so that lubricity tends to be inferior. The number of perfluoroalkylene oxide group constituting the X ^a is preferably 1 to 50.

X ^a may be a perfluoropolyether chain having two or more kinds of perfluoroalkylene oxide groups as structural units.

When X ^a has two or more kinds of perfluoroalkylene oxide groups as structural units, X ^a is a perfluoropolyether chain in which the perfluoroalkylene oxide groups form one block for each type. Is also good. That, X ^a is perfluoroalkylene oxide groups the q l is perfluoroalkylene oxide group number p and the number of carbon atoms of the k number of carbon atoms _{- (C k F 2k O)} p (C l F
_2lO ) _q- .
Alternatively, three kinds of perfluoroalkylene oxide groups each having k, l, and m carbon atoms are p
Number, q pieces, and the r _{exists, - (C k F 2k O} ) p (C l F
_{2l O) q (C m F} 2m O) r - may be those formed by arranging as. The same applies to the case where the number of perfluoroalkylene oxide groups is 4 or more.

When X ^a is a perfluoropolyether chain having two or more kinds of perfluoroalkylene oxide groups as structural units, X ^a has 2 to 7 carbon atoms.
It is preferable that the perfluoroalkylene oxide group is a perfluoropolyether chain formed by bonding three to three, more preferably two, types of perfluoroalkylene oxide groups to form 1 to 30 blocks, respectively, and connecting these blocks.

When two or more kinds of perfluoroalkylene oxide groups are used as the structural unit, the arrangement form is not limited to the above-mentioned form. For example, a perfluoroalkylene oxide group may form a block for each type, and the blocks may be arranged regularly or randomly.
Further, the perfluoroalkylene oxide groups may be arranged regularly or randomly, for example, alternately.

In the general formula (A), f is an integer of 1 or more, preferably 1 to 6. When f is large, the proportion of-(CF ₂ ) -chains in the whole molecule becomes large, so that the number of ether bonds becomes small as compared with a compound having the same molecular weight, and lubrication performance may be deteriorated.

In the general formula (A), g is preferably an integer of 1 to 10. That is, it is preferable that 1 to 10 methylene chains exist as recurring units in one molecule in order to ensure good solubility in general-purpose organic solvents. However, in the general formula (A), a methylene chain is not always necessary, and g may be 0. The absence of the methylene chain does not adversely affect the performance of the lubricant.

[0043] Z ^a in the general formula (A) is a fluorine atom or a polar group. The polar group serves to improve the ability of the lubricant to adsorb the lubricant to the carbon film. The polar group is specifically, a carboxyl group (—COOH), a hydroxyl group (—OH), an amino group (—NH ₂ ), an amide group (—C
ONH _2), a mercapto group (-SH), nitrile group (-
CN), a phosphone group (—P (O) (OH) ₂ ), an epoxy group, a halogen group and the like. Also, -COOR
An alkoxycarbonyl group represented by ¹ or -OCOR ²
May be an acyloxyl group represented by R ¹ and R ² are an alkyl group or an alkenyl group;
R ¹ and R ² preferably have 1 to 22 carbon atoms, more preferably 12 to 18 carbon atoms. In the present invention, the polar group is particularly preferably a carboxyl group or a hydroxyl group. When Za is ^a fluorine atom, the compound represented by the general formula (A) is a perfluoropolyether having no polar group.

In the general formula (A), the carbon skeleton structure of ^Ra can be determined in relation to the carbon skeleton structure of a perfluoroalkylene oxide group adjacent via an oxygen atom. For example, the carbon skeleton structure of ^Ra may be the same as the carbon skeleton structure of a perfluoroalkylene oxide group adjacent via an oxygen atom. That is, for example, when the perfluoroalkylene oxide group adjacent to R ^a via an oxygen atom is — (CF ₂ O) —, R ^a
May be CF ₃ . Alternatively, the carbon skeleton structure of ^Ra may be different from the carbon skeleton structure of the adjacent perfluoroalkylene oxide group via an oxygen atom. In that case, R ^a is preferably carbon atoms 1-2
It is preferable to have a carbon skeleton structure that is 0,
More preferably, it has a carbon skeleton structure having 1 to 8 carbon atoms. As an example, as in the compound represented by the chemical formula (13) used in the examples, In the general formula (A), the perfluoropolyether chain X ^a is only perfluoroalkylene oxide group having 3 carbon atoms and the structural unit And g is 2, and the carbon skeleton structure of ^Ra is n-
Examples thereof include fluoropolyether compounds which are not propyl groups, for example, n-heptyl groups.

The second embodiment of the fluoropolyether compound contained in the lubricant of the present invention has the general formula (B):

Embedded image (Wherein X ^b is a linear perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit, Z ^b1 and Z ^b2 are polar groups, and i is an integer of 1 or more. And h and j are integers of 0 or more).

In the general formula (B), X ^b is a linear perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit. Since the structure of perfluoroalkylene oxide groups are as described for earlier X ^a, where a detailed description thereof will be omitted.

[0047] X ^b is similar to X ^a, may be a perfluoropolyether chain of one perfluoroalkylene oxide groups and structural units. In that case, the number of carbon atoms in the perfluoroalkylene oxide group is preferably 1 to 7 from the viewpoint of lubrication performance and stability of the compound,
More preferably, it is 2 to 4. When the number of carbon atoms is large, the number of ether bonds is smaller than that of a compound having the same molecular weight, so that lubricity tends to be inferior. The number of perfluoroalkylene oxide groups constituting ^Xb is 2 to 5
It is preferably 0.

X ^b may be a perfluoropolyether chain having two or more kinds of perfluoroalkylene oxide groups as structural units. Such a perfluoropolyether chain may be, for example, a perfluoropolyether chain in which a perfluoroalkylene oxide group forms one block for each type. Specific structures of such perfluoropolyether chain, because as has been described in connection with the earlier X ^a, where a detailed description thereof will be omitted.

When X ^b is a perfluoropolyether chain having two or more kinds of perfluoroalkylene oxide groups as structural units, X ^b has 2 to 7 carbon atoms.
It is preferable that three, more preferably two, types of perfluoroalkylene oxide groups are formed by bonding 1 to 30 each to form a block. For example, 2
When a kind of perfluoroalkylene oxide group is used as a structural unit, at least one kind of perfluoroalkylene oxide group can have 3 or more carbon atoms.

When two or more kinds of perfluoroalkylene oxide groups are used as the structural units, their arrangement is not limited to the above-mentioned one. For example, a perfluoroalkylene oxide group may form a block for each type, and the blocks may be regularly arranged. An example of such a compound is shown in Example 16 described later (chemical formula (15)). Alternatively, such blocks may be randomly arranged. Further, the perfluoroalkylene oxide groups may be arranged regularly or randomly, for example, alternately.

In the general formula (B), i is an integer of 1 or more, preferably 1 to 6. When i is large, the proportion of-(CF ₂ )-chains in the whole molecule becomes large, so that the number of ether bonds becomes small as compared with a compound having the same molecular weight, and lubrication performance may be deteriorated.

In the general formula (B), h and j are 1 to
It is preferably an integer of 10. That is, it is preferable that 1 to 10 methylene chains exist as a repeating unit between the polar group and the perfluoropolyether chain in order to ensure good solubility in general-purpose organic solvents. However, in the general formula (B), a methylene chain is not always necessary, and h and / or j may be 0. The absence of the methylene chain does not adversely affect the performance of the lubricant. H and j may be the same or different.

Z ^b1 and Z ^b2 in the general formula (B) are polar groups. Since preferred polar group is as described with respect to Z ^a in the general formula (A) above, where a detailed description thereof will be omitted. Z ^b1 and Z ^b2 may be the same or different from each other.

The third embodiment of the fluoropolyether compound contained in the lubricant of the present invention has the general formula (C):

Embedded image (Wherein, R ^c is a fluorine atom or a perfluoroalkyl group, X ^c is a linear perfluoroether chain or a perfluoropolyether chain, Z ^c is a polar group, and u is an integer of 0 or more. ) Having three or more repeating units represented by the formula:

In the general formula (C), R ^c is a fluorine atom or a perfluoroalkyl group, and is preferably a fluorine atom in the present invention. When R ^c is a perfluoroalkyl group, it preferably has 1 to 7 carbon atoms, and more preferably 2 to 4 carbon atoms.

In the general formula (C), X ^c is a linear perfluoroether chain or a perfluoropolyether chain forming at least one ether bond. X ^c
In the above, it is preferable that the number of carbons constituting X ^c is 1 to 7.

X ^c may contain at least one kind of perfluoroalkylene oxide group. X ^c may contain one kind of perfluoroalkylene oxide group, in which case the number of carbon atoms of the perfluoroalkylene oxide group is preferably 1 to 7, and the number of perfluoroalkylene oxide groups is 1 to 12 It is preferred that Also, X ^c
Two or more perfluoroalkylene oxide groups,
One block may be formed and included for each type. Alternatively, two or more types of perfluoroalkylene oxide groups may form a block for each type, and the blocks may be arranged regularly or randomly. Further, two or more kinds of perfluoroalkylene oxide groups are
For example, they may be arranged regularly or alternately so as to be alternated.

In the general formula (C), u is preferably an integer of 1 to 10. That is, it is preferable that 1 to 10 methylene chains be present as a repeating unit in one repeating unit represented by the general formula (C) in order to ensure good solubility in a general-purpose organic solvent. However, in the general formula (C), a methylene chain is not always necessary, and u may be 0. The absence of the methylene chain does not adversely affect the performance of the lubricant.

Z ^c in the general formula (C) is a polar group. Z ^a in the general formula (A) Preferred polar groups like the previous
Has been described above, and a detailed description thereof will be omitted here.

[0060] In general formula (C) fluoropolyether compounds consisting of repeating units represented by the number of the repeating unit represented by the general formula (C) has a total compound according to the structure of X ^c is a suitable molecular weight And generally the molecular weight of the entire compound is from 500 to 50
It is preferable to make 00. Further, it is preferable that a fluorine atom is bonded to the repeating units located at both ends of the fluoropolyether compound. Examples of such compounds are shown in Examples 18 and 19 below (see chemical formulas (16) and (17)).

As described above, preferred embodiments of the fluoropolyether compound contained in the lubricant of the present invention are represented by the general formula (A):
Although shown in (B) and (C), the lubricant of the present invention may contain a fluoropolyether-based compound which is a modified form thereof. For example, the above general formulas (A) to
At least one fluorine atom bonded to a carbon atom constituting the fluoropolyether compound represented by (C) comprises a perfluoroalkyl group, a perfluoroalkenyl group, a perfluoroether group and a perfluoropolyether group It may be a perfluoropolyether compound substituted with a group selected from the group. In that case, the resulting perfluoropolyether compound is a compound having a structure in which a side chain is bonded to a fluoropolyether chain having a linear main skeleton.

The general formulas (A), (B) and (C)
Wherein at least one fluorine atom bonded to a carbon atom constituting the compound has the general formula (D):

Embedded image (Wherein, v is an integer of 0 or more, and Z ^d is a polar group). V in the general formula (D) is an integer of 0 or more, and preferably 1 to 10. However, a methylene chain is not always necessary, and v may be 0. The absence of the methylene chain does not adversely affect the performance of the lubricant. Z ^d is a polar group. Preferred polar groups and the like are those described above in the general formula (A).
^Since it is as described for a, a detailed description thereof will be omitted here.

The substituent represented by the general formula (D) may be bonded instead of at least one fluorine atom bonded to a carbon atom constituting the above-mentioned fluoropolyether compound, and the number thereof is 2 It may be the above. Also, Z
^d may be a polar group different from Z ^a , Z ^b1 and Z ^b2 , or Z ^c . For example, a substituent represented by the general formula (D) may be further bonded to a perfluoropolyether chain to the fluoropolyether compound represented by the general formula (B). The number of polar groups contained in one molecule is 3 or more. Also,
The repeating unit represented by the general formula (C) is represented by the general formula (D)
May be combined to form a repeating unit in which a plurality of polar groups are combined.

The molecular weight of any of the above-mentioned fluoropolyether compounds is preferably in the range of 200 to 20,000, more preferably in the range of 500 to 5,000. If the molecular weight is too small, there is a problem that the stability is poor, and if the molecular weight is too large, there is a problem that the lubricity is poor.

The above-mentioned fluoropolyether compound is
Instead of polymerizing a fluorinated monomer as in the prior art, it can be produced by a production method including a step of directly fluorinating a hydrocarbon polyether by a fluorination method in the presence of a hydrogen fluoride scavenger. . The fluorination is preferably a so-called perfluorination in which all the hydrogen of the hydrocarbon polyether is replaced by fluorine. According to this production method, a polyether having a predetermined main skeleton may be fluorinated, so that unlike a case where a fluorinated monomer is polymerized, a fluoropolyether having a predetermined molecular weight and a predetermined molecular structure is used. It can be obtained with high purity. Therefore, according to this production method, a purification step unlike the conventional fluoropolyether is not required.

The method of directly fluorinating a hydrocarbon polyether is described in detail in Japanese Patent Publication No. 7-64929, and the description can be referred to in actual production. The contents disclosed in this publication by this citation constitute a part of the present specification.

The hydrocarbon polyether to be fluorinated is, for example, polyoxyalkylene alkyl ether or polyoxyethylene polyoxyalkylene ether.

As a method for producing a perfluoropolyether having a polar group, for example, an alcohol such as polyoxyethylene glycol, polyoxyalkylene glycerin, or a modified erythritol having a plurality of alkylene oxide groups is used as a starting material. There is a method of subjecting this to a predetermined reaction after fluorination. For example, these alcohols are perfluorinated by a direct fluorination method to produce a perfluoropolyether compound whose terminal is modified to acid fluoride (—COF), and then hydrolyzed to convert the carboxyl group into a polar group. Is obtained. Perfluoropolyether carboxyl group Reduction of the compound -CH ₂ OH next having the carboxyl group, perfluoropolyether compound having a hydroxyl group is obtained.

When a perfluoropolyether compound having a carboxyl group is reacted with ammonia, the carboxyl group becomes -CONH ₂ and a perfluoropolyether compound having an amide group is obtained. Reduction of the perfluoropolyether compound having the amide group, amide group -CH ₂ NH _2, and the perfluoropolyether compound having an amino group is obtained.
When the perfluoropolyether compound having an amide group is dehydrated, a perfluoropolyether compound having a nitrile group is obtained.

The perfluoropolyether compound having an alkoxycarbonyl group can be obtained by subjecting a perfluoropolyether compound having a carboxyl group to a predetermined aliphatic alcohol by an esterification reaction. The perfluoropolyether compound having an acyloxyl group can be obtained by subjecting a perfluoropolyether compound having a hydroxyl group to a predetermined aliphatic carboxylic acid by an esterification reaction.

Further, by reacting a perfluoropolyether having a hydroxyl group with thionyl halide (SOX ₂ ; X is a halogen), a perfluoropolyether having a hydroxyl group replaced by a halogen and a polar group being a halogen group is used. A compound is obtained. Then, the perfluoropolyether compound having a halogen group is reacted with potassium hydrosulfide to obtain a perfluoropolyether compound having a mercapto group. Also,
A perfluoropolyether compound having a phosphonic group as a polar group can be produced by an esterification reaction between a perfluoropolyether compound having a hydroxyl group and phosphorus trichloride.

When a compound whose polar group is a hydroxyl group, an amino group, a halogen group or a mercapto group is obtained from an alcohol as a starting material by the method described above,
The polar group has a structure bonded to at least one methylene chain. Therefore, g in the general formula (A), h or j in the general formula (B), or u in the general formula (C) is an integer of 1 or more.

The fluoropolyether compound synthesized in this manner can be identified by gel permeation chromatography (GPC), infrared spectroscopy (IR), and organic mass spectroscopy (FD-MS). From these analyses, it can be seen that the fluoropolyether compound obtained by fluorination according to the predetermined method is higher in purity than a commercially available perfluoropolyether compound or a perfluoropolyether compound obtained by purifying a commercially available product.

The lubricant of the present invention comprises at least one kind of the above-mentioned fluoropolyether compound. Also,
A mixture of two or more of the above fluoropolyether compounds may be used as the lubricant. The lubricant of the present invention may be composed of only the above-mentioned fluoropolyether compound, but is a composition containing other lubricant components, a rust preventive, an extreme pressure agent and the like as appropriate. You may. In that case, the proportion of the above-mentioned fluoropolyether compound in the composition is preferably 40% by weight or more, more preferably 50% by weight or more. If the proportion of the above fluoropolyether compound is less than 40% by weight, for example, when a lubricant layer of a magnetic recording medium is formed with this composition, good lubricating properties cannot be imparted to the magnetic recording medium. There are cases.

As another lubricant component, for example, a fluorinated alkyl carboxylic acid monoester may be mixed. The fluorine-containing alkyl carboxylic acid monoester is, for example, represented by the following general formula (E):

Embedded image (Wherein, R ³ represents an alkyl group or an alkenyl group;
R ⁴ represents a fluoroalkyl group or a fluoroether group or a fluoropolyether group, and x is 0 or 1
And y is an integer of 0 to 20). The compound represented by the general formula (E) has one fluorine-containing terminal group, that is, a fluoroalkyl group or a fluoroether terminal group or a fluoropolyether terminal group, and one hydrocarbon terminal group, that is, an alkyl group in the same molecule. The structure has a terminal group or an alkenyl terminal group and one carboxyl group.

In the general formula (E), R ³ is an alkyl group or an alkenyl group, and preferably has 6 to 30 carbon atoms, more preferably 10 to 24 carbon atoms. When the number of carbon atoms is less than 6, or exceeds 30, the lubricity may be reduced.

When R ⁴ is a fluoroalkyl group, it preferably has 1 to 12 carbon atoms, more preferably 6 to 10 carbon atoms. Further, the fluoroalkyl group is preferably a perfluoroalkyl group.

When R ⁴ is a fluoroether group or a fluoropolyether group, the molecular weight is preferably about 200 to about 6000, and is preferably about 300 to about 40.
More preferably, it is 00. When the molecular weight is less than 200 or more than 6,000, lubricity and reliability may decrease. Further, the fluoroether group or the fluoropolyether group is preferably a perfluoroether group or a perfluoropolyether group.

When R ⁴ is a fluoroether group or a fluoropolyether group, R ⁴ has the general formula (F):
(G) and (H):

Embedded image (Where K is an integer of 1 or more)

Embedded image (Where P and Q are integers of 1 or more)

Embedded image (Wherein, R ⁵ represents a fluoroalkyl group, M is an integer of 1 to 6, and N is an integer of 1 to 30).

In the general formula (F), K is an integer of 1 or more, preferably 1 to 8.

In the general formula (G), P and Q are integers of 1 or more, both of which are preferably 1 to 30, more preferably 1 to 8.

R ⁵ in the general formula (H) is a fluoroalkyl group, preferably a perfluoroalkyl group;
It preferably has 1 to 30 carbon atoms, and more preferably 1 to 8 carbon atoms. M is usually an integer of 1 to 6. N is usually an integer of 1 to 30, more preferably 1
８8.

When K, P and Q, and M and N in the general formulas (F), (G) and (H) are out of these ranges, the lubricity and storage reliability of the magnetic recording medium decrease. There is.

The method for synthesizing the above-mentioned fluorine-containing carboxylic acid used in the present invention is described in US Pat.
No. 5, Japanese Patent Application No. 10-184790, and the contents described in these publications constitute a part of the specification of the present invention by this citation.

Alternatively, the lubricant of the present invention may further comprise, as a lubricant component, at least one fluoropolyether compound represented by any of the above general formulas (A) to (C).
It may contain a perfluoropolyether alkyl carboxylic acid diester. Here, the perfluoropolyether-based alkyl carboxylic acid diester refers to a perfluoropolyether-based compound having two ester bonds in one molecule in which a hydrogen atom of a carboxylic acid is substituted with an alkyl group.

In the present invention, the perfluoropolyether alkylcarboxylic diester is preferably represented by the following general formula (I):

Embedded image (Wherein, X is —OCOR ⁶ , wherein R ⁶ represents an alkyl group or an alkenyl group, r and s are integers of 1 or more, and t is an integer of 0 to 12). It is preferably at least one compound selected from the compounds.

In the compound represented by the general formula (I), h and j are limited to 0 to 12 in the general formula (B), and X ^b is (CF ₂ O) (C ₂ F ₄ O) _r ( CF ₂ O) _s , i
Is 1 and Z ^b1 and Z ^b2 are —OCOR ⁶ . Therefore, when the lubricant of the present invention contains the compound represented by the general formula (I) as another lubricant component, the lubricant includes the compound represented by the general formula (A) or the general formula (C), or And at least one compound represented by the general formula (B) but not the compound represented by the general formula (I).

X in the general formula (I) is an acyloxyl group —OCOR ⁶ . R ⁶ represents an alkyl group or an alkenyl group, and preferably has an integer of 1 to 24 carbon atoms, and more preferably 12 to 20 carbon atoms. r and s are integers of 1 or more, and both are preferably 1 to 30, and more preferably 1 to 8. t
Is an integer of 0 to 12, preferably 0 to 6.

The compound represented by formula (I) preferably has a molecular weight of about 1,000 to about 20,000, more preferably about 1,000 to about 4,000. Therefore, it is preferable that the number of carbon atoms constituting r ⁶ , and r, s, and t be selected so that the molecular weight of the compound is within this range.

The compound represented by the general formula (I) is
It is obtained by subjecting a conventionally known or commercially available perfluoropolyether compound to a predetermined chemical reaction, as long as X, r and s, t in the general formula (I) satisfy the above conditions. May be. For example, perfluoroether compounds having hydroxyl groups at both ends of the molecule (for example,
By subjecting Fomblin Z Dol (having a hydroxyl group as a polar group) produced by Ausimont to a carboxylic acid represented by R ⁶ COOH, a compound represented by the general formula (I) is obtained.

The lubricant of the present invention may contain both the alkyl carboxylic acid monoester and the perfluoropolyether alkyl carboxylic acid diester. In this case, the alkyl carboxylic acid monoester and the perfluoropolyether-based alkyl carboxylic acid diester are mixed at a weight ratio of 1: 9 to 9: 1. It is good to be included in the ratio of less than.

In the lubricant of the present invention, a commercially available perfluoropolyether lubricant is used as another lubricant component to be mixed with the fluoropolyether compounds represented by the general formulas (A) to (C). It can also be used. The commercially available perfluoropolyether that can be used here preferably has a molecular weight of about 1,000 to about 20,000, particularly preferably about 1,000 to about 4,000. Specifically, the perfluoropolyether compounds exemplified in the section of the prior art can be used.

The lubricant of the present invention may further contain an organic phosphorus compound. In the present invention, the above general formulas (J) to (J)
It is preferable to use at least one type of organic phosphorus compound selected from the group consisting of the organic phosphorus compounds represented by (R). In the organic phosphorus compounds represented by the general formulas (J) to (R), the number of carbon atoms n is preferably from 8 to 20, and more preferably from 12 to 18.
When the number of carbon atoms n is 21 or more, the solubility in general-purpose solvents such as hydrocarbon solvents and alcohol solvents described below tends to decrease. For example, when the lubricant layer of the magnetic recording medium is composed of a lubricant containing the same, the decrease in solubility in the general-purpose solvent may hinder the production of the magnetic recording medium by the production method of the present invention. When the carbon number n is 7 or less,
Lubrication performance of the lubricant may be reduced.

The mixing ratio of the total amount of the lubricant to the organic phosphorus compound is preferably in the range of 1: 1 to 1: 0.01 by weight, more preferably in the range of 1: 0.3 to 1: 0.02. Range. When the mixing ratio of the organophosphorus compound is too large, the lubricating performance deteriorates, and when it is too small, the action and effect of the organophosphorus compound cannot be sufficiently obtained.
The total amount of the lubricant means the total amount of the lubricant excluding the organic phosphorus compound, and includes a compound other than the above-mentioned predetermined fluoropolyether compound as a lubricating component in the lubricant. Quantity.

The magnetic recording medium of the present invention comprises a ferromagnetic metal film provided on a nonmagnetic support, and a lubricant layer provided on the ferromagnetic metal film via a carbon film. Wherein the lubricant layer comprises a lubricant containing the above-mentioned predetermined perfluoropolyether compound. In the present invention, the amount of the predetermined fluoropolyether-based compound contained in the lubricant layer is 1 m per surface of the lubricant layer.
It is preferably 0.1 to 50 mg per ² and 0.5
~ 5 mg is more preferred. In order for such a small amount of the compound to be uniformly present in the lubricant layer, the lubricant layer of the magnetic recording medium of the present invention is desirably formed by the following method.

The lubricant layer is formed on the carbon film after forming a ferromagnetic metal thin film and a carbon film on the non-magnetic support in this order using conventional materials and means. The step of forming a lubricant layer includes a step of applying a coating solution prepared by dissolving the lubricant of the present invention in a mixed solvent of a hydrocarbon solvent and an alcohol solvent on a carbon film, and a step of drying the mixed solvent. including. Finally, when the mixed solvent evaporates, the lubricant dissolved in the solvent remains on the carbon film to form a lubricant layer. Therefore, even when the coating liquid is applied thickly, the solvent evaporates, forming a uniform and very thin lubricant layer on the carbon film, that is, a lubricant layer in which a small amount of lubricant uniformly covers the carbon film. Is done.

The hydrocarbon solvents that can be used in the present invention include, for example, toluene, hexane, heptane, octane, nonane, xylene, and ketones. The alcohol solvents that can be used in the present invention include, for example, methyl alcohol, ethyl alcohol, and the like. It is a lower alcohol such as alcohol, propyl alcohol, isopropyl alcohol and butyl alcohol. If the proportion of the alcohol-based solvent is too large, coating unevenness tends to occur. On the other hand, if the proportion of the hydrocarbon-based solvent is too large, it is disadvantageous in terms of cost. Therefore, the mixing ratio of the two is 1: 9 to 9: 1, preferably 3: 7-7:
It is preferable to mix and use them so as to be in the range of 3. The concentration and the thickness of the coating solution are applied so that the lubricant layer formed on the carbon film after the solvent evaporates has a desired thickness. Generally, the concentration of the lubricant is 100 to 100.
It is preferable to apply a coating solution of 00 ppm so as to have a thickness of 10 to 100 μm.

The method of forming the lubricant layer using the above-mentioned mixed solvent includes a wet coating method such as a bar coating method, a gravure coating method, a reverse roll coating method, a die coating method, a dip coating method and a spin coating method, or an organic method. There is a vapor deposition method, and either method may be adopted.

After the application of the coating solution, the organic solvent is evaporated by a drying treatment to form a lubricant layer on the carbon film.
The drying treatment can be performed by heating or natural drying. Then, the thickness of the finally obtained lubricant layer is preferably about 3 to 5 nm. However, since there is an optimum range of the thickness of the lubricant layer depending on the composition of the lubricant, the thickness of the lubricant layer is not necessarily limited to this range.

As described above, by using a predetermined mixed organic solvent, a lubricant layer having a uniform thickness without coating unevenness can be obtained, and after the solvent is finally evaporated, a very thin lubricant layer of several nm is obtained. An agent layer can be formed. As a result, a highly reliable magnetic recording medium having excellent lubrication performance can be obtained.

As described above, the magnetic recording medium of the present invention can be formed by using conventional materials and means for layers other than the lubricant layer.

Examples of the nonmagnetic support include films made of polyethylene terephthalate, polyethylene naphthalate, aromatic polyamide or aromatic polyimide, vinyl resins such as polyvinyl chloride or polyvinylidene chloride, polycarbonate, aluminum substrates, and glass substrates. , A metal such as aluminum, copper, a light metal such as an aluminum alloy or a titanium alloy, single crystal silicon, paper, or the like. this house,
When a rigid substrate such as an aluminum alloy plate or a glass substrate is used as the nonmagnetic substrate, an oxide film such as alumite treatment or a Ni-P film may be formed on the substrate surface to harden the surface. . In order to achieve both practical reliability and good RF output value, the surface of the non-magnetic substrate, that is, the surface in contact with the ferromagnetic metal film, is subjected to a projection forming process with a diameter of 50 to 700 nm and a height of 5 to 70 nm. Is desirable.

The magnetic layer constituting the magnetic recording medium of the present invention is a ferromagnetic metal thin film formed by a method such as an ion plating method, a sputtering method, or an electron beam evaporation method. The thin film material is Co-Ni, Co-Ni-
O, Co, Co-O, Co-Cr and the like are appropriately selected. The thickness of the magnetic layer is generally between 30 nm and 300 nm.

The carbon film has a Vickers hardness of about 2500 kg.
/ Mm ² , preventing damage to the magnetic tape together with the lubricant layer. In consideration of the balance between practical reliability and output, the thickness is preferably 1 to 20 nm. This carbon film is preferably graphite-like carbon or diamond-like carbon formed by a plasma CVD method using only a hydrocarbon gas or a mixed gas of a hydrocarbon gas and an inert gas. Since diamond-like carbon has an appropriate hardness, it is the most preferable material because it can suppress damage to a magnetic recording medium and also prevent damage to a magnetic head.

More specifically, the carbon film is formed by introducing a hydrocarbon gas or a mixed gas of a hydrocarbon gas and an inert gas such as argon into a vacuum vessel, and adjusting the pressure in the vessel to 0.13 to 130.
Discharge is generated inside the vacuum vessel while maintaining Pa, and a plasma of hydrocarbon gas is generated to form a carbon film on the ferromagnetic metal thin film. The discharge type may be either an external electrode type or an internal electrode type, and the discharge frequency can be determined experimentally. Further, by applying a voltage of 0 KV to -3 KV to the electrode disposed on the non-magnetic substrate side, the hardness of the carbon film can be increased, and the adhesion between the carbon film and the ferromagnetic metal thin film can be improved. be able to. As hydrocarbon gas, methane, ethane, propane, butane,
Pentane, hexane, heptane, octane or benzene can be used.

In order to form a hard carbon film,
It is desirable to increase the discharge energy, and it is also desirable to keep the temperature of the non-magnetic substrate high. For example, as for the discharge energy, it is desirable that an alternating current, for example, a high-frequency current and a direct current are superimposed to have an effective value of 600 V or more.

In the present invention, it is preferable that a nitrogen-containing plasma polymerized film is formed on the surface of the carbon film, and the lubricant layer is formed on the nitrogen-containing plasma polymerized film of the carbon film. Amino groups are present in the surface layer of the carbon film due to the nitrogen-containing plasma polymerized film, and as a result, the adhesion strength between the lubricant layer and the carbon film is increased, and the durability of the magnetic recording medium is further improved. It will be. In combination with the inclusion of a specific fluorine-containing compound or the like in the lubricant layer, practical durability with improved running durability and still durability having excellent lubrication performance without impairing electromagnetic conversion characteristics. A high magnetic recording medium can be obtained.

The nitrogen-containing plasma polymerized film is obtained by gasifying and introducing an amine compound such as propylamine, butylamine, ethylenediamine, propylenediamine or tetramethylenediamine into a vacuum vessel and reducing the pressure in the vessel to 0.1.
With the pressure kept at 3 to 130 Pa, high-frequency discharge is performed inside the vacuum vessel to form the vacuum container. The thickness of the nitrogen-containing plasma polymerized film is 3 nm
If the nitrogen-containing plasma polymerized film is thicker than this, the protective effect of the carbon film is reduced. The method of forming the nitrogen-containing plasma polymerized film on the surface layer of the carbon film is as follows.
Nos. 5,540,957 and 5,637,393, the disclosures of which are hereby incorporated by reference.

In the case where a back coat layer is provided, the back coat layer is formed of one or more materials selected from polyurethane, nitrocellulose, polyester, carbon, calcium carbonate, and the like. preferable.

[0110]

EXAMPLES Next, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

(Example 1) The chemical formula of the substance of this example is represented by the following chemical formula (1).

Embedded image This is because C ₃ H ₇ O (C ₂ H ₄ O) ₄ H is
Perfluorination according to the method described in 29,
_{3 H 7 O (C 2 H} 4 O) 3 CF 2 after the acid fluoride represented by the COF, in which the terminal by reducing it obtained denatured to -CH ₂ OH.

A graph showing the GPC absorption peak of this compound is shown in FIG. As shown in FIG.
Only a single peak was detected, and no peak derived from compounds other than the fluoroalkylene oxide group-containing alkyl alcohol was not detected. This indicates that the purity of the obtained compound is high. In addition, matters obtained by performing infrared spectroscopy (IR) and FD-MS on the obtained compound are summarized below. IR; absorption peak of alcohol at 3,330 cm ^-1 . FD-MS; main peak at m / e 614.

Example 2 As a non-magnetic substrate, the thickness was 6.3 μm, the height was 30 nm, and the diameter was 20 μm.
A polyethylene terephthalate film having 10 ⁵ to 10 ⁹ protrusions of 0 nm per mm ² was used. The number of protrusions is a value measured by STM analysis. On the surface of the non-magnetic substrate, a 180 nm thick ferromagnetic metal thin film made of Co (80) -Ni (20) (the molar ratio in parentheses) was formed by oblique vacuum evaporation while introducing oxygen.

Then, on the back surface of the non-magnetic substrate, methyl ethyl ketone / toluene / toluene / solid 30% composed of polyurethane, nitrocellulose and carbon black was used.
The cyclohexanone solution was applied by a reverse roll coater to form a back coat layer having a thickness of about 500 nm after drying.

Next, plasma CVD is performed on the ferromagnetic metal thin film.
A carbon film having a thickness of 15 nm was formed by the method. The carbon film is
A gas in which hexane gas and argon gas are mixed at a ratio of 4: 1 (pressure ratio) is introduced into a vacuum vessel, and while maintaining the total gas pressure at 39 Pa, a frequency of 20 KHz and a voltage of 1500 are applied.
It was formed by superimposing an alternating current of V and a direct current of 1000 V and applying this to electrodes in the discharge tube. Further, a propylamine gas is introduced onto the carbon film, and a high-frequency plasma treatment of 10 KHz is performed while maintaining a pressure of 6.5 Pa to form a 2.5-nm-thick nitrogen-containing plasma polymerized film on the surface of the carbon film. did.

Next, a lubricant consisting of the compound represented by the chemical formula (1) was added to a mixed organic solvent in which isopropyl alcohol and toluene were mixed at a weight ratio of 1: 1.
A coating solution was prepared by dissolving so as to have a concentration of 2000 ppm. The coating solution was applied to a thickness of about 80 μm by a wet coating method using a reverse roll coater, and then dried. Finally, a lubricant layer containing 5 mg of lubricant per m ² was formed on the carbon film. The tape material prepared as described above was cut into a width of 8 mm with a slitter, and a magnetic tape sample of 8 mm width (total thickness 7 μm, 60
Length) was prepared.

(Examples 3 to 19) Instead of the compound represented by the chemical formula (1), the compounds represented by the chemical formulas (2) to (17) (Example 3)
To 19) were used as lubricants, except that magnetic tape samples were produced in the same manner as in Example 2. In Example 2, three kinds of compounds having different numbers (n) of perfluoroethylene oxides were separately manufactured, and they were added in a weight ratio of 1 to 1.
A mixture of (n = 2): 2 (n = 3): 1 (n = 4) was used.

[0118]

Embedded image (Where n is an integer of 2 to 4)

[0119]

Embedded image

[0120]

Embedded image

[0121]

Embedded image

[0122]

Embedded image

[0123]

Embedded image

[0124]

Embedded image

[0125]

Embedded image

[0126]

Embedded image

[0127]

Embedded image

[0128]

Embedded image

[0129]

Embedded image

[0130]

Embedded image

[0131]

Embedded image

[0132]

Embedded image

[0133]

Embedded image

[0134]

Embedded image

(Example 20) Lubrication in which the compound represented by the chemical formula (1) and the compound represented by the chemical formula (19) were mixed at a weight ratio of 1: 1 instead of the compound represented by the chemical formula (1) A magnetic tape sample was prepared in the same manner as in Example 2 except that the agent was used.

Embedded image

(Example 21) Lubrication in which the compound represented by the chemical formula (1) and the compound represented by the chemical formula (20) were mixed in a weight ratio of 1: 1 instead of the compound represented by the chemical formula (1) A magnetic tape sample was prepared in the same manner as in Example 2 except that the agent was used.

Embedded image

Example 22 Instead of the compound represented by the chemical formula (1), the compound represented by the chemical formula (1), the compound represented by the chemical formula (21), and the compound represented by the chemical formula (20) were added in a weight ratio. A magnetic tape sample was prepared in the same manner as in Example 2 except that a lubricant compounded at a ratio of 2: 1: 1 was used.

Embedded image

(Example 23) Instead of the compound represented by the chemical formula (1), the compound represented by the chemical formula (1) and (C ₁₂
A magnetic tape sample was prepared in the same manner as in Example 2, except that a lubricant containing an organophosphorus compound represented by H ₂₅ S) ₃ P at a weight ratio of 4: 1 was used.

Example 24 A magnetic tape sample was prepared in the same manner as in Example 2, except that the step of forming the nitrogen-containing plasma polymerized film on the surface portion of the carbon film was omitted.

(Example 25) A magnetic tape sample was prepared in the same manner as in Example 2 except that the weight ratio of the mixed organic solvent composed of isopropyl alcohol and toluene was changed from 1: 1 to 8: 1. .

Example 26 A magnetic tape sample was prepared in the same manner as in Example 2 except that the weight ratio of the mixed organic solvent composed of isopropyl alcohol and toluene was changed from 1: 1 to 1: 8. .

(Comparative Example 1) Instead of the compound represented by the chemical formula (1), the main skeleton is-(C ₂ F ₄ O) _p (CF ₂ O) _q-
(P and q are integers of 1 or more), and a commercially available perfluoropolyether-based lubricant having a hydroxyl group as a polar group at both ends of the molecule (Fomblin Z DOL, average molecular weight 200
0, manufactured by Ausimont) as a lubricant,
A magnetic tape sample was produced in the same manner as in Example 2.

(Comparative Example 2) The main skeleton was-(C ₂ F ₄ O) _p (CF ₂ O) _q- instead of the compound represented by the chemical formula (1).
(P and q are integers of 1 or more) and a commercially available perfluoropolyether-based lubricant (Fomblin Z Diac, average molecular weight 4000, manufactured by Ausimont) having a carboxyl group at both ends of the molecule as a polar group is disclosed in 9-291296
According to the method described in Japanese Patent Application Publication No. H07-163, a perfluoropolyether-based compound purified by esterifying a carboxyl group, extracting the ester compound with a good solvent, and hydrolyzing the ester compound to a carboxyl group is used as a lubricant. A magnetic tape sample was produced in the same manner as in Example 2 except that the magnetic tape sample was used.

(Comparative Example 3) Instead of the compound represented by the chemical formula (1), the main skeleton is-(C ₂ F ₄ O) _p (CF ₂ O) _q-
(P and q are integers of 1 or more), and a commercially available perfluoropolyether-based lubricant having hydroxyl groups as polar groups at both ends of the molecule (Fomblin Z DOL, average molecular weight 20)
00, manufactured by Ausimont) according to the method described in Japanese Patent No. 2677074, an ester solvent as a good solvent,
A magnetic tape sample was prepared in the same manner as in Example 2, except that a perfluoropolyether compound purified using an alcohol solvent as a poor solvent was used as a lubricant.

Comparative Example 4 A magnetic tape sample was prepared in the same manner as in Example 2 except that only isopropyl alcohol was used instead of the mixed organic solvent consisting of isopropyl alcohol and toluene.

Comparative Example 5 A magnetic tape sample was prepared in the same manner as in Example 2 except that only toluene was used instead of the mixed organic solvent consisting of isopropyl alcohol and toluene.

The above Examples 2 to 26 and Comparative Examples 1 to
The following evaluation tests (1) and (2) were performed on the magnetic tape samples having a width of 8 mm obtained in Example 5, and the results obtained in each test were shown in Tables 1 and 2 for Examples 2 to 26. 2 and Comparative Examples 1 to 5 are shown in Table 3.

(1) Running durability test Commercially available 8 mm VTR modified for RF (high frequency) output measurement
Using a Sony (EV-S900, manufactured by Sony Corporation), each 8 mm wide tape sample was subjected to 300 passes at 5 ° C. and 80% RH for 300 passes.
The change in RF output after repetitive reproduction for 00 hours was measured. Changes after the test compared to before the test are shown in decibels. The tape damage was evaluated in five stages by visually observing the tape sample and observing the state with a differential interference microscope. The evaluation criteria are as follows. 5: There is no problem in practical use. 4: There is no practical problem. 3: Practical, but needs improvement. 2: The tape is severely damaged and practically not practical. 1: The tape damage is too bad and there is no practicality at all.

(2) Still life test The initial still life was calculated using a commercially available 8 modified for still life measurement.
mmVTR (EV-S900, manufactured by Sony Corporation)
C. and 5% RH. In addition, the still life was represented by the time from the initial stage until the output decreased by 6 dB.
The post-storage still life was measured in the same manner as in the initial still life measurement after leaving it for one month in an environment of 40 ° C. and 80% RH.

[0150]

[Table 1] Reduction in running durability Still life output Tape still life Initial still life Still life after storage (dB) (Minutes) (Minutes) Example 2-1.15> 60 40 Example 3-1.05> 60 42 Example 4-1.25> 60 39 Example 5-1.35> 60 41 Example 6 -1.04> 6044 Example 7 -1.15> 60 35 Example 8 -1.05> 60 35 Example 9 -1.45> 60 40 Example 10 -1.25> 6044 Example 11-1.34> 6039 Example 12-1.34> 6039 Example 13-1.35> 6050

[0151]

[Table 2] Decrease in running durability still life output taper machine Initial still life Still life after storage (dB) (Minutes) (Minutes) Example 14 -1.35> 60 44 Example 15 -1.25> 60 40 Example 16 -1.45> 60 42 Example 17 -1.25> 60 39 Example 18 -1.24> 60 38 Example 19 -1.25> 60 41 Example 20 -1.15>60> 60 Example 21 -1.25>60> 60 Example 22 -1.0 5>60> 60 Example 23 -1.35>60> 60 Example 24 -2.05> 60 32 Example 25 -1.45> 60 60 Example 26 -1.05> 60 58

[0152]

[Table 3] Reduction of running durability still life output Tape still life Initial still life Still life after storage (dB) (Minutes) (Min) Comparative Example 1-6.6 1 14 1 Comparative Example 2 -7.8 1 15 1 Comparative Example 3 -3.5 4 5 4 Comparative Example 4 -4.3 2 259 Comparative Example 5 -3.9 3 335

As is clear from Tables 1 to 3, in comparison with Comparative Examples 1 to 5, the output drops of Examples 2 to 26 were small, and no problem of tape damage occurred. The remaining still lifes were all good.

Examples 2 to 3 in which a fluoropolyether compound having a predetermined molecular structure was used as a lubricant in a lubricant layer
The magnetic tape samples of Nos. 26 and 26 showed superior running durability and still life compared to the magnetic tape samples of Comparative Examples 1 to 3 in which the conventional lubricant or a refined conventional lubricant was contained in the lubricant layer. showed that.

Further, in addition to the fluoropolyether compound having a predetermined molecular structure, a fluorine-containing alkyl carboxylic acid monoester or perfluoropolyether alkyl carboxylic acid diester having a predetermined molecular structure is contained in the lubricant layer. In Examples 20 and 21, the still life was improved. In Example 22 in which both the fluorinated alkyl carboxylic acid monoester and the perfluoropolyether alkyl carboxylic acid diester having a predetermined molecular structure were contained in the lubricant layer, the still life was also improved.

In the magnetic tape sample of Example 23 in which the organic phosphorus compound was contained in the lubricant layer, the still life was improved, and although not particularly shown in Table 2, the initial still life was significantly improved. Was admitted. Further, since the still life of the sample of Example 24 after storage was inferior, it was found that the nitrogen-containing plasma polymerized film contributed to the improvement of the lubricating performance of the magnetic tape sample.

By comparing the performances of the samples of Examples 2, 25 and 26 and the samples of Comparative Examples 4 and 5, the magnetic recording media manufactured based on the manufacturing method of the present invention show excellent performance. I understand.

(Embodiment 27) An embodiment of another magnetic recording medium according to the present invention will now be described specifically. In this embodiment, the non-magnetic support of the magnetic recording medium has a diameter of 95 mm,
A non-magnetic Ni-P alloy plating having a thickness of 25 μm was applied to the surface of an Al alloy plate having a thickness of 1.2 mm, and projections having an average roughness of 5 nm and a maximum height of 30 nm were formed by texturing. On the non-magnetic Ni-P alloy plating of this support,
A 130 nm thick Cr underlayer and a 60 nm thick Co-Ni ferromagnetic metal thin film were formed by sputtering. Further, a diamond-like carbon carbon film having a thickness of 5 nm was formed on the ferromagnetic metal thin film by a plasma CVD method. Subsequently, a propylamine gas was introduced onto the carbon film, and a high-frequency plasma treatment at 10 KHz was performed while maintaining a pressure of 6.5 Pa, and a nitrogen-containing plasma polymerized film having a thickness of 2.5 nm was formed on the surface of the carbon film. Formed. Next, a lubricant composed of the compound represented by the chemical formula (1) is dissolved in a mixed organic solvent in which isopropyl alcohol and toluene are mixed at a weight ratio of 1: 1 so as to have a concentration of 2000 ppm, and applied. The liquid was adjusted. Then, apply this coating solution to about 8
After coating by a wet coating method (dip coating method) so as to have a thickness of 0 μm, it was dried. Finally, a magnetic disk sample was obtained in which a lubricant layer containing 5 mg of lubricant per m ² was formed on the carbon film.

(Examples 28 to 44) Compounds represented by chemical formulas (2) to (18) (corresponding to examples 28 to 44) were used as lubricants instead of the compound represented by chemical formula (1). Except for the above, magnetic disk samples were produced in the same manner as in Example 24.

(Example 45) A lubrication in which the compound represented by the chemical formula (1) and the compound represented by the chemical formula (19) were mixed at a weight ratio of 1: 1 instead of the compound represented by the chemical formula (1) A magnetic disk sample was prepared in the same manner as in Example 27 except that the agent was used.

(Example 46) A lubrication in which the compound represented by the chemical formula (1) and the compound represented by the chemical formula (20) were blended at a weight ratio of 1: 1 instead of the compound represented by the chemical formula (1) A magnetic disk sample was prepared in the same manner as in Example 27 except that the agent was used.

Example 47 Instead of the compound represented by the chemical formula (1), the compound represented by the chemical formula (1) and the compound represented by the chemical formulas (19) and (20) were in a weight ratio of 2: 1: A magnetic disk sample was prepared in the same manner as in Example 27 except that the lubricant compounded at a ratio of 1 was used.

Example 48 Instead of the compound represented by the formula (1), a compound represented by the formula (1) and (C ₁₂
A magnetic disk sample was produced in the same manner as in Example 27, except that a lubricant containing an organic phosphorus compound represented by H ₂₅ S) ₃ P at a weight ratio of 4: 1 was used.

Example 49 A magnetic disk sample was manufactured in the same manner as in Example 27 except that the step of forming a nitrogen-containing plasma polymerized film on the surface portion of the carbon film was omitted.

Example 50 A magnetic disk sample was produced in the same manner as in Example 27, except that the weight ratio of the mixed organic solvent composed of isopropyl alcohol and toluene was changed from 1: 1 to 8: 1. .

Example 51 A magnetic disk sample was prepared in the same manner as in Example 27 except that the weight ratio of the mixed organic solvent composed of isopropyl alcohol and toluene was changed from 1: 1 to 1: 8. .

Comparative Example 6 The procedure of Example 1 was repeated except that the same commercially available perfluoropolyether-based lubricant as used in Comparative Example 1 was used instead of the compound represented by the chemical formula (1). A magnetic disk sample was manufactured in the same manner as in No. 27.

Comparative Example 7 The same compound as in Comparative Example 2 and a perfluoropolyether compound obtained by using the purification method were used as a lubricant instead of the compound represented by the chemical formula (1). A magnetic disk sample was manufactured in the same manner as in Example 27.

(Comparative Example 8) In place of the compound represented by the chemical formula (1), the same compound as in Comparative Example 3 and a perfluoropolyether compound obtained by using the purification method were used as a lubricant. A magnetic disk sample was manufactured in the same manner as in Example 27.

Comparative Example 9 A magnetic disk sample was prepared in the same manner as in Example 27 except that only isopropyl alcohol was used instead of the mixed organic solvent consisting of isopropyl alcohol and toluene.

Comparative Example 10 A magnetic disk sample was prepared in the same manner as in Example 27 except that only toluene was used instead of the mixed organic solvent consisting of isopropyl alcohol and toluene.

The above Examples 27 to 51 and Comparative Example 6
5 ° C. for each magnetic disk sample obtained in
Under the environment of 10% RH, the environment of 40 ° C and 80% RH, and the environment of 5 ° C and 80% RH, CSS (contact
Start / stop) test and the friction coefficient is 1.0
The durability was determined by measuring the number of CSSs at the time of exceeding the threshold value or the number of CSSs at the time of occurrence of a head crash. The results obtained in this test are shown in Tables 4 and 5 for Examples 27 to 51, and in Table 6 for Comparative Examples 6 to 10.

[0173]

[Table 4] CSS frequency (times) Magnetic disk 5 ° C, 10% RH 40 ° C, 80% RH 5 ° C, 80% RH Example 27 50,000 or more 50,000 or more 50,000 Example 28 50,000 More than 50,000 or more 50,000 Examples 29 50,000 or more 50,000 or more 50,000 Examples 30 50,000 or more 50,000 or more 50,000 Examples 31 50,000 or more 50,000 or more 50,000 Examples 32 50,000 or more 50,000 or more 50,000 or more 50,000 Examples 33 50,000 or more 50,000 or more 50,000 Examples 34 50,000 or more 50,000 More than 50,000 Examples 35 50,000 or more 50,000 or more 50,000 Examples 36 50,000 or more 50,000 or more 50,000 Examples 37 50,000 or more 50,000 or more 50,000 Examples 38 or more 50,000 or more 50,000 or more 50,000

[0174]

[Table 5] CSS frequency (times) Magnetic disk 5 ° C, 10% RH 40 ° C, 80% RH 5 ° C, 80% RH Example 39 50,000 or more 50,000 or more 50,000 Example 40 50,000 More than 50,000 or more 50,000 Examples 41 50,000 or more 50,000 or more 50,000 Examples 42 50,000 or more 50,000 or more 50,000 Examples 43 50,000 or more 50,000 or more 50,000 Examples 44 50,000 or more 50,000 or more 50,000 or more 45 50,000 or more 50,000 or more 50,000 or more Examples 46 50,000 or more 50,000 or more 50,000 or more Example 47 50,000 or more 50,000 or more 50,000 or more Example 48 50,000 or more 50,000 or more 50,000 or more Example 49 50,000 50,000 or more 50,000 Example 50 50,000 or more 50,000 or more 50,000 Example 51 51 50,000 or more 50,000 or more 50,000

[0175]

[Table 6] CSS frequency (times) Magnetic disk 5 ° C, 10% RH 40 ° C, 80% RH 5 ° C, 80% RH Comparative example 6 5,000 8,000 5,000 Comparative example 7 18,000 * 5,000 5,000 * Comparative example 8 5,000 7,000 2,000 Comparative example 9 20,000 * 10,000 * 5,000 Comparative example 10 5,000 * 15,000 * 5,000 *

As is clear from Tables 4 to 6, in comparison with Comparative Examples 6 to 10, the CS of Examples 27 to 51
The S durability test results were all good.

Embodiment 45 In addition to a fluoropolyether compound having a predetermined molecular structure, a lubricant layer containing a fluorinated alkyl carboxylic acid monoester and a perfluoropolyether alkyl carboxylic acid diester having a predetermined molecular structure in a lubricant layer was used. In Nos. 46 and 46, the CSS durability in an environment of 5 ° C. and 80% RH was improved, and particularly excellent durability was exhibited. In Example 47 in which both the fluorinated alkyl carboxylic acid monoester and the perfluoropolyether-based alkyl carboxylic acid diester having a predetermined molecular structure were contained in the lubricant layer, the CSS durability was similarly improved.

The magnetic disk sample of Example 48 containing an organophosphorus compound in the lubricant layer also had a temperature of 5 ° C. and 80%
Improvement in CSS durability under RH environment was observed. Further, the CSS durability of the sample of Example 49 in an environment of 5 ° C. and 10% RH was inferior to those of the other examples.
It is understood that the nitrogen-containing plasma polymerized film contributes to the improvement of the lubrication performance of the magnetic disk sample.

By comparing the performance of the samples of Examples 27, 50 and 51 with the samples of Comparative Examples 9 and 10,
It can be seen that the magnetic recording medium manufactured based on the manufacturing method of the present invention shows excellent performance.

[0180]

The lubricant of the present invention contains a fluoropolyether compound having a molecular structure which has never been obtained by perfluorinating a hydrocarbon ether or a hydrocarbon polyether having a predetermined molecular structure, or a modified product thereof. And exhibit excellent lubrication performance. Therefore,
The lubricant of the present invention is useful as a lubricant for various machines, devices or parts.

Therefore, the lubricant of the present invention is contained in the lubricant layer of a magnetic recording medium in which a ferromagnetic metal thin film, a carbon film and a lubricant layer are provided in this order on a nonmagnetic support. The recording medium has excellent lubricity and durability,
In addition, the lubricity does not decrease in a wide range of environments from a low temperature and low humidity environment to a high temperature and high humidity environment. This magnetic recording medium is particularly suitable for use in digital video tape recorders and HDDs.

Further, the lubricant of the present invention is more excellent by containing a fluorinated alkyl carboxylic acid monoester and / or a perfluoropolyether alkyl carboxylic acid diester in addition to the above specific fluoropolyether compound. The lubrication performance can be improved.
Further, the lubricant of the present invention can exhibit more excellent lubricating performance by adding an organic phosphorus compound. Therefore, the magnetic recording medium of the present invention including these lubricants in the lubricant layer has better lubricity and durability.

By forming the carbon film of the magnetic recording medium of the present invention from diamond-like carbon, the effect of protecting the carbon film is improved, and the bonding force with the lubricant layer is also improved. Further, by forming a nitrogen-containing plasma polymerized film on the surface layer of the carbon film, the bonding force between the carbon film and the lubricant layer is improved, and a magnetic recording medium having more excellent durability can be obtained.

For the lubricant layer of the magnetic recording medium of the present invention, a lubricant is dissolved in a mixed solvent of a hydrocarbon solvent and an alcohol solvent to prepare a coating solution, and this coating solution is coated on a carbon film. Formed by Use of this mixed solvent suppresses coating unevenness and enables formation of a thin and uniform lubricant layer.

[Brief description of the drawings]

FIG. 1 is a graph showing GPC measurement results of the fluoropolyether obtained in Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/72 G11B 5/72 5/725 5/725 5/84 5/84 B // C10N 40:18 F-term (Reference) 4H104 BD06C BD07C BE04A BE11A BG13A BH02C BH03A BH03C BH06C CD04A CE19A CG09A CH09A LA20 PA16 5D006 AA01 AA02 AA06 5D112 AA07 BC02 BC05 CC01

Claims (33)

[Claims] 1. A compound of the general formula (A): Wherein R ^a is a perfluoroalkyl group or a perfluoroalkenyl group, and X ^a is a linear perfluoroether chain or a perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit. Wherein ^Za is a fluorine atom or a polar group, f is an integer of 1 or more, and g is an integer of 0 or more.) 2. The lubricant comprising a fluoropolyether compound according to claim 1, wherein X ^a is a perfluoroether chain or a perfluoropolyether chain having one type of perfluoroalkylene oxide group as a structural unit. . 3. A lubricant comprising the fluoropolyether compound according to claim 1, wherein the perfluoroalkylene oxide group has 2 to 4 carbon atoms. 4. The lubricant comprising a fluoropolyether compound according to claim 1, wherein X ^a is a perfluoropolyether chain having two or more perfluoroalkylene oxide groups as structural units. Carbon backbone structure wherein R ^a is the same as the carbon skeleton structure of perfluoroalkylene oxide group adjacent to R ^a via an oxygen atom (if the number of carbon atoms constituting the perfluoroalkylene oxide is 3 A lubricant comprising the fluoropolyether compound according to claim 2 or 3. Carbon backbone structure wherein R ^a is, through an oxygen atom include a fluoropolyether compounds according to claim 4 is the same as the carbon skeleton structure of perfluoroalkylene oxide group adjacent to R ^a Lubricant consisting. Carbon backbone structure 7. R ^a is fluoro polyether according to any one of claims 1 to 6, different from the carbon skeleton structure of perfluoroalkylene oxide group adjacent to R ^a via an oxygen atom A lubricant comprising a system compound. 8. The general formula (B): (Wherein X ^b is a linear perfluoropolyether chain having at least one kind of perfluoroalkylene oxide group as a structural unit, Z ^b1 and Z ^b2 are polar groups, and i is an integer of 1 or more. And h and j are integers of 0 or more). 9. A lubricant comprising the fluoropolyether compound according to claim 8, wherein X ^b has one kind of perfluoroalkylene oxide group as a structural unit. 10. A lubricant comprising the fluoropolyether compound according to claim 8, wherein the perfluoroalkylene oxide group has 2 to 4 carbon atoms. 11. The lubricant comprising a fluoropolyether compound according to claim 8, wherein X ^b is a perfluoropolyether chain having two or more types of perfluoroalkylene oxide groups as structural units. 12. The lubricant comprising the fluoropolyether compound according to claim 11, wherein X ^b has two types of perfluoroalkylene oxide groups as structural units. 13. The at least one kind of perfluoroalkylene oxide group has 3 or more carbon atoms.
A lubricant comprising the fluoropolyether-based compound described in 1 above. 14. The general formula (C): (Wherein, R ^c is a fluorine atom or a perfluoroalkyl group, X ^c is a linear perfluoroether chain or a perfluoropolyether chain, Z ^c is a polar group, and u is an integer of 0 or more. A lubricant comprising a fluoropolyether compound having three or more repeating units represented by the formula: 15. A lubricating oil comprising the fluoropolyether compound according to claim 14, wherein X ^c is a perfluoroether chain or a perfluoropolyether chain containing at least one kind of perfluoroalkylene oxide group. Agent. 16. The method according to claim 16, wherein the polar group is -COOH, -OH, -N
^{_{H 2, -CONH 2, -COOR 1}} (R 1 is an alkyl group or an alkenyl group), - OCOR ² (R ² is an alkyl group or an alkenyl group), - SH, -CN, P
A lubricant comprising the fluoropolyether compound according to any one of claims 1 to 15, selected from the group consisting of (O) (OH) ₂ , an epoxy group and a halogen group. 17. At least one fluorine atom bonded to a carbon atom constituting the fluoropolyether compound according to any one of claims 1 to 16, is a perfluoroalkyl group, a perfluoroalkenyl group, A lubricant comprising a fluoropolyether compound substituted with a group selected from the group consisting of a perfluoroether group and a perfluoropolyether group. 18. At least one fluorine atom bonded to a carbon atom constituting the fluoropolyether compound according to claim 1 is a compound represented by the general formula (D): (Wherein v is an integer of 0 or more and Z ^d is a polar group). A lubricant comprising a fluoropolyether compound substituted with a group represented by the formula: 19. A lubricant comprising the fluoropolyether compound according to claim 1, having a molecular weight of 200 to 20,000. 20. The method according to claim 1, wherein the fluoropolyether compound is produced by a production method including a step of fluorinating a hydrocarbon polyether in the presence of a hydrogen fluoride scavenger. The lubricant according to claim 1. 21. The lubricant according to claim 1, further comprising a fluorinated alkyl carboxylic acid monoester. 22. A fluorine-containing alkyl carboxylic acid monoester having the general formula (E): (Wherein, R ³ represents an alkyl group or an alkenyl group;
R ⁴ represents a fluoroalkyl group or a fluoroether group or a fluoropolyether group, and x is 0 or 1
And y is an integer of 0 to 20), wherein the lubricant is at least one compound selected from the group consisting of: 23. In the fluorine-containing alkyl carboxylic acid monoester represented by the general formula (E), R ⁴ is represented by the general formulas (F), (G) and (H): (Where K is an integer of 1 or more) (Wherein, P and Q are integers of 1 or more). (Wherein, R ⁵ represents a fluoroalkyl group, M is an integer of 1 to 6, and N is an integer of 1 to 30).
The lubricant described in 1. 24. The lubricant according to claim 1, further comprising a perfluoropolyether alkyl carboxylic acid diester. 25. The perfluoropolyether-based alkyl carboxylic acid diester has the general formula (I): (Wherein, X is —OCOR ⁶ , wherein R ⁶ represents an alkyl group or an alkenyl group, r and s are integers of 1 or more, and t is an integer of 0 to 12). The lubricant according to claim 24, wherein the lubricant is at least one compound selected from perfluoropolyether alkyl carboxylic acid diesters. 26. At least one compound selected from a fluorinated alkyl carboxylic acid monoester represented by the general formula (E) and a perfluoropolyether alkyl carboxylic acid diester represented by the general formula (I) The lubricant according to any one of claims 1 to 20, further comprising at least one compound to be used. 27. The lubricant according to claim 1, further comprising an organic phosphorus compound. 28. The organic phosphorus compound represented by the general formula (J):
(K), (L), (M), (N), (O), (P),
(Q) and (R): Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image (In the above general formulas (J) to (R), n is 8 to 20)
At least one member selected from the group consisting of:
28. The lubricant of claim 27, which is a class of compounds. 29. A magnetic recording medium comprising: a ferromagnetic metal thin film provided on a non-magnetic support; and a lubricant layer provided on the ferromagnetic metal thin film via a carbon film. A magnetic recording medium comprising at least one kind of the lubricant according to any one of claims 1 to 28. 30. The magnetic recording medium according to claim 29, wherein the carbon film is made of diamond-like carbon. 31. The carbon film has a nitrogen-containing plasma polymerized film on a surface layer portion thereof, and the lubricant layer is formed on the nitrogen-containing plasma polymerized film of the carbon film. 3. The magnetic recording medium according to claim 1. 32. The method for manufacturing a magnetic recording medium according to claim 29, wherein the step of forming the lubricant layer comprises the step of forming the lubricant layer using a mixed organic solvent of an alcohol solvent and a hydrocarbon solvent. A method for producing a magnetic recording medium, comprising a step of applying a coating solution prepared by dissolving a lubricant on a carbon film. 33. The method for producing a magnetic recording medium according to claim 32, wherein the mixing ratio of the alcohol solvent and the hydrocarbon solvent is in the range of 1: 9 to 9: 1 by weight.