Lubricant composition comprising:

at least one base oil; and

0.1 to 30% by weight of an imidazoline compound of formula (A):

##STR00001##

defined such that:

R.sup.1 represents a linear or branched alkyl or alkenyl group comprising 1 to 16 carbon atoms, optionally substituted at the end of the chain by a group selected from among NH.sub.2, OH or SH; and

R.sup.2 represents a linear or branched alkyl or alkenyl group comprising 1 to 36 carbon atoms.

A fluorine-containing ether compound represented by the formula (1) is provided. The fluorine-containing ether compound is represented by the following formula (1). R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4 (1) (R.sup.3 is a perfluoropolyether chain; R.sup.1 is the formula (2), a in the formula (2) is an integer of 2 or 3, R.sup.5 and R.sup.6 are the same or different substituents. R.sup.5 and R.sup.6 may form a ring structure together with a nitrogen atom; R.sup.2 is the formula (3), b in the formula (3) is an integer of 1 to 3; R.sup.4 is a terminal group having two or three polar groups, in which individual polar groups bond to different carbon atoms and the carbon atoms to which the polar groups bond are bonded to each other through a linking group having a carbon atom to which the polar groups do not bond.)

##STR00001##

A fluorine-containing ether compound represented by a formula (1) shown below.

R.sup.1—(O(CH.sub.2).sub.a).sub.b-[A]-[B]—O—CH.sub.2—R.sup.2—CH.sub.2—R.sup.3  (1)

(In the formula (1), R.sup.1 is an alkyl group which may have a substituent, or an organic group having at least one double bond or triple bond. Further, a represents an integer of 2 to 4, and b is 0 or 1. [A] is represented by a formula (2): —(OCH.sub.2CH(OH)CH.sub.2).sub.c— (wherein c is 1 or 2). [B] is represented by a formula (3): —(O(CH.sub.2).sub.eCH(OH)CH.sub.2).sub.d— (wherein d is 0 or 1, and e represents an integer of 2 to 4). However, the sum of c in the formula (2) and d in the formula (3) is 2. R.sup.2 is a perfluoropolyether chain. R.sup.3 is represented by a formula (4): —(OCH.sub.2CH(OH)CH.sub.2).sub.2—O—CH.sub.2(CH.sub.2).sub.fOH (wherein f represents an integer of 2 to 5).

The invention provides a fullerene compound; a lubricant that is for a magnetic recording medium and that contains the fullerene compound; and a magnetic recording medium. The fullerene compound is an ionic liquid that is represented by general formula (1) and is formed from a Bronsted acid (H.sub.n1X) and a Bronsted base ([R.sub.2R.sub.3)N—].sub.m1—R.sub.1); wherein one of the Brønsted acid and the Broønsted base contains a group having a fullerene; and the other contains a perfluoroalkyl chain. ##STR00001##

Disclosed is a method of lubrication including a step of lubricating a machine with a lubricating composition, the lubricating composition including 20-100% ionic liquid or of a mixture of several ionic liquids. The ionic liquid or the mixture is selected from at least: an anion A.sup.− chosen from sulfonylimides, the substituent(s) of which is (are) independently chosen from a fluoroalkyl, fluoroether, perfluorinated alkyl or perfluoroether group; and a cation C.sup.+ including a nitrogen-containing heterocycle or a quaternary ammonium, the substituent(s) of which is (are) independently chosen from: a hydrogen atom or alkyl, alkoxy, fluorinated alkyl, perfluorinated alkyl, alkylsilane, alkyl alcohol, vinyl, alkyl allyl, ether or polyether groups having a linear or branched chain having 1-3 carbon atoms. The deposition start temperature in thin film of the ionic liquid or of the mixture of ionic liquids is at least equal to 330° C. The lubricating composition reduces deposits formed in the machine.

An antifriction coating formulation composition comprising (a) a soluble resin, (b) an insoluble polymer, (c) optionally a solid lubricant, and (d) a solvent.

The invention provides a fullerene compound; a lubricant that is for a magnetic recording medium and that contains the fullerene compound; and a magnetic recording medium. The fullerene compound is an ionic liquid that is represented by general formula (1) and is formed from a Bronsted acid (H.sub.n1X) and a Bronsted base ([R.sub.2R.sub.3)N—].sub.m1—R.sub.1); wherein one of the Brønsted acid and the Broønsted base contains a group having a fullerene; and the other contains a perfluoroalkyl chain.

##STR00001##

A lubricant, which includes an ionic liquid including a conjugate base and a conjugate acid including 2 or more cations in a molecule of the conjugate acid, wherein the conjugate acid includes a monovalent group including a straight-chain hydrocarbon group having 6 or more carbon atoms, and an acid that is a source of the conjugate base has a pKa in acetonitrile of 10 or less.

A fluorine-containing ether compound represented by the formula (1) is provided. The fluorine-containing ether compound is represented by the following formula (1). R.sup.1R.sup.2CH.sub.2R.sup.3CH.sub.2R.sup.4 (1) (R.sup.3 is a perfluoropolyether chain; R.sup.1 is the formula (2), a in the formula (2) is an integer of 2 or 3, R.sup.5 and R.sup.6 are the same or different substituents. R.sup.5 and R.sup.6 may form a ring structure together with a nitrogen atom; R.sup.2 is the formula (3), b in the formula (3) is an integer of 1 to 3; R.sup.4 is a terminal group having two or three polar groups, in which individual polar groups bond to different carbon atoms and the carbon atoms to which the polar groups bond are bonded to each other through a linking group having a carbon atom to which the polar groups do not bond.) ##STR00001##

A lubricant including: an ionic liquid, which includes a conjugate acid (B.sup.+) and a conjugate base (X.sup.), and is protic, wherein the ionic liquid is represented by the following general formula (1), and wherein the conjugate base is a conjugate base of sulfonic acid, a conjugate base of sulfonimide, or a conjugate base of trisulfonylmethide: ##STR00001##
where R.sup.1 and R.sup.2 each represent a hydrogen atom or R.sup.1 and R.sup.2 form a benzene ring together with carbon atoms to which R.sup.1 and R.sup.2 are bonded, R.sup.3 represents a to straight-chain hydrocarbon group having 10 or more carbon atoms, and R.sup.4 represents a hydrogen atom or a hydrocarbon group in the general formula (1).