A fluorine-containing ether compound of the present invention is represented by the following General Formula (1). (In the General Formula (1), X is a trivalent atom or a trivalent atom group, A is a linking group including at least one polar group, B is a linking group having a perfluoropolyether chain, and D is a polar group or a substituent having a polar group at the end.)
[Chem. 1]
XA-B-D).sub.3  (1)

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. In the formula (1), R.sup.1 is represented by the following formula (2), R.sup.2 is represented by the following formula (3), R.sup.3 is a perfluoropolyether chain, and R.sup.4 is an organic end group different from R.sup.1—R.sup.2— and contains two or three polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are bonded to one another via a linking group containing a carbon atom to which the polar group is not bonded. In the formula (2), r is 1 to 3. In the formula (3), w is 2 or 3. ##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).

An ionic liquid comprising: a cation (or conjugate acid), wherein the cation (or conjugate acid) is represented by General Formula (A) below or General Formula (B) below or General Formula (C) or General Formula (D) below or General Formula (E) below: ##STR00001## wherein R.sub.1 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or an alkyl chain CH.sub.3, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; R.sub.2 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or a hydrogen atom H, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; and R.sub.3 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7.

Provided is a compound which allows realization of a lubricant having high adsorbability and a high covering property with respect to a magnetic disk, particularly a carbon protective film. A perfluoropolyether compound in accordance with an aspect of the present invention has a naphthyl group or a phenoxyphenyl group at any one of terminals thereof.

An object of an aspect of the present invention is to provide: a lubricant excellent in adsorbability on the surface of a magnetic disk and in contamination resistance; and a magnetic disk which uses the lubricant and which is excellent in durability. The lubricant in accordance with an aspect of the present invention contains a fluoropolyether compound having, at a terminal thereof, a hydroxyalkenyl group or a hydroxyalkynyl group.

Provided is a fluorine-containing ether compound that can be suitably used as a material for a lubricant for a magnetic recording medium, capable of forming a lubricant layer having excellent chemical substance resistance and wear resistance even when the thickness is small. A fluorine-containing ether compound represented by the following formula (1):
R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4—R.sup.5  (1) In the formula (1), R.sup.3 is a perfluoropolyether chain. R.sup.2 and R.sup.4 are divalent linkage groups having a polar group, and may be the same or different. R.sup.1 and R.sup.5 are terminal groups bonded to R.sup.2 or R.sup.4, which may be the same or different, and at least one of R.sup.1 and R.sup.5 is an organic group having 1 to 8 carbon atoms wherein one or more hydrogen atoms of the organic group is substituted with a cyano group.

A lubricant including an ionic liquid including a conjugate base and a conjugate acid, wherein the conjugate acid is represented by General Formula (A) below, and wherein a pKa of an acid that is a source of the conjugate base in acetonitrile is 10 or less,

##STR00001##

where, in General Formula (A), R is a group including a straight-chain hydrocarbon group having 6 or greater carbon atoms, and R.sub.1 and R.sub.2 are each independently a hydrocarbon group.

Bearing device comprising: —a first bearing surface and a second bearing surface which are moveable relative to one another and which face one another, wherein the first bearing surface and second bearing surface are separated by a bearing gap filled with a lubricant, wherein the lubricant comprises a carrier fluid and particles which respond to magnetic or electric fields, wherein said particles are suspended in the carrier fluid in the absence of magnetic or electric fields, —one or more field generators which are embedded in the first or second bearing surface, wherein the field generators are magnetic or electric field generators configured to generate a localized magnetic or electric field which is configured to locally remove the particles from suspension by exerting a field force on the particles, thereby forming a local flow obstruction on at least one of the bearing surfaces in the form of an agglomerate of previously suspended particles, wherein the local flow obstruction is configured to locally obstruct a flow of the lubricant through the bearing gap in an obstruction zone.

Provided is a lubricant composition including a bicyclic liquid crystal of formula (1), and a tricyclic liquid crystal compound of formula (2), and having a mixing mass ratio of the bicyclic liquid crystal compound and tricyclic liquid crystal compound of 95:5 to 15:85. The composition is suitable for use in a clean environment, under a high vacuum, under high temperature and a bearing.

##STR00001##

R.sup.1 and R.sup.2 are the same or different from each other, and each is —OCH.sub.2CH.sub.2CH(R′)CH.sub.2CH.sub.2OR

##STR00002##

R.sup.11 and R.sup.21 are the same or different from each other, and each is —OR. R.sup.12, R.sup.13, R.sup.22 and R.sup.23 are the same or different from each other, and each is hydrogen or —OR. R is a linear or branched C.sub.nH.sub.2n+1, 1≤n≤20 and R′ is methyl or ethyl.