The present invention relates to a novel process for the synthesis of (per)fluoropolyether polymers and to certain novel (per)fluoropolyether polymers. The present invention also relates to the use the (per)fluoropolyether polymers thus obtained, as intermediate compounds for the manufacture of further polymers suitable for use as lubricants, notably for magnetic recording media (MRM).

A camera module includes a lens module including a lens, and a base module configured to accommodate the lens module therein. A fluorinated lubricant is disposed on a portion of at least one of the lens module and the base module, the fluorinated lubricant includes a fluorescent material capable of emitting fluorescent light when illuminated with ultraviolet (UV) light.

A lubricant composition includes a base oil and melamine cyanurate. The base oil includes a perfluoropolyether oil having a straight chain structure. The lubricant composition is for one of a resin-resin sliding section and a resin-metal sliding section. A melamine cyanurate content is within a range of 1-20% by mass with respect to a sum of the base oil and melamine cyanurate.

A lubricant composition includes a perfluoropolyether as a base oil, a fluororesin as a thickener, and a polyol ester, a urea grease and a zinc dialkyldithiophosphate as additives, wherein a mass ratio of content of the perfluoropolyether to total content of the polyol ester and the urea grease ranges from 78/22 to 95/5, a mass ratio of content of the perfluoropolyether to content of the polyol ester ranges from 90/10 to 96.5/3.5, a mass ratio of content of the polyol ester to content of the urea grease ranges from 40/60 to 65/35, content of the fluororesin ranges from 15 mass % to 24 mass % based on a total amount of the lubricant composition, and content of the zinc dialkyldithiophosphate ranges from 0.5 mass % to 4 mass % based on the total amount of the lubricant composition.

Grease composition contains (A) a straight-chain perfluoropolyether having a kinematic viscosity of 2-110 mm.sup.2/s at 40 C., (B) a branched perfluoropolyether having a kinematic viscosity of 2-100 mm.sup.2/s at 40 C., and (C) a fluorocarbon resin powder having a primary particle size of 1 m or less, wherein the contained amount of the fluorocarbon resin powder is 25-40 wt % with respect to the weight of the grease composition, and the weight ratio of the straight-chain perfluoropolyether (A) to the branched perfluoropolyether (B) is 15:85 to 70:30.

A fluorine-containing ether compound represented by the following formula (1).
R.sup.1R.sup.2CH.sub.2R.sup.3CH.sub.2R.sup.4(1)
(R.sup.1 is an organic group having an alicyclic structure having 3 to 13 carbon atoms; R.sup.2 is represented by the following formula (2), and a in the formula (2) is an integer of 1 to 3; R.sup.3 is a perfluoropolyether chain; and 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##

The present invention relates to a phosphazene compound [compound (L)] comprising a cyclophosphazene central core wherein each phosphorus atom of said core bears a substituent independently selected from: a) a chain (A), said chain (A) comprising a (per)fluoropolyether chain [chain (R.sub.f)], one or more aromatic or heteroaromatic moieties [moiety/ies (Ar.sup.m)] and, optionally, one or more hydroxy groups and b) a chain (B), said chain (B) comprising a (per)fluoropolyether chain [chain (R.sub.f)] and one or more hydroxy groups with the proviso that at least one phosphorous atom of the central core is substituted with chain (A) and to mixtures of compounds (L). The invention further relates to methods for preparing compounds (L), to lubricant compositions comprising compounds (L) and to methods for lubricating magnetic recording media comprising applying a compound (L) or a lubricant compositions containing them to the surface of said medium.

The invention provides a grease composition for lubrication of a sliding surface made of resin, including a fluorine-based base oil and a synthetic hydrocarbon oil as a base oil; a fluorine-based thickener, and a lithium soap thickener or a lithium complex soap thickener as a thickener; and an extreme pressure additive as an additive. The invention also provides a sliding member including a sliding surface made of a resin wherein the grease composition for lubrication is applied to the sliding surface made of a resin.

A lubricant for a magnetic recording medium capable of forming a lubricant layer having excellent adhesion to a protective layer is provided. A lubricant for a magnetic recording medium contains a fluorine-containing ether compound in which a group having an ethylenic carbon-carbon double bond is disposed at one or both terminals of a perfluoroalkyl polyether chain. It is preferable that the group having the ethylenic carbon-carbon double bond is disposed at one terminal of the perfluoroalkyl polyether chain, and a hydroxyl group is disposed at other terminal. It is preferable that the lubricant for a magnetic recording medium contains a compound in which one or more functional groups selected from a hydroxyl group, an amino group, an amido group and a carboxyl group is disposed at one or both terminals of a perfluoroalkyl polyether chain.

A fluorine-containing ether compound represented by the following formula (1) is provided.

R.sup.2CH.sub.2R.sup.1CH.sub.2OCH.sub.2CH(OH)(CH.sub.2).sub.nCH(OH)CH.sub.2OCH.sub.2R.sup.1CH.sub.2R.sup.2(1)

(in the formula (1), n is an integer of 2 to 6, R.sup.1 is a perfluoropolyether chain, R.sup.2 is OCH.sub.2CH(OH)CH.sub.2O(CH.sub.2).sub.mOH (m in the formula is an integer of 2 to 4)).