A method for preparing a high viscosity index poly-α-olefin subjects α-olefin to a polymerization reaction in the presence of a metallocene catalyst to obtain a poly-α-olefin. The polymerization reaction is carried out in the absence of a solvent, and the metallocene catalyst is formed of, or is formed by interaction between, a metallocene compound and an activator.

The invention relates to a lubricant composition comprising: at least one base oil for coming into contact with food, selected from the groups II, III or V according to the categories defined in the API classification or the equivalents thereof according to the ATIEL classification; at least one hydrogenated polyisobutylene; and at least one ester polymer.

According to one aspect of the present invention, an organic fluorine compound is represented by a general formula
(R-π-E-CH.sub.2-A-CH.sub.2-E′).sub.n-π′-G  (1B) (where n is an integer of 2 to 5, A is a divalent perfluoropolyether group, π is an arylene group or a single bond, R is an alkenyl group or an alkynyl group, and E and E′ are each independently an ether bond or an ester bond or a group that is represented by a chemical formula
—O—CH.sub.2CH(OH)CH.sub.2O—
π′ is a group in which n+1 hydrogen atoms are separated from benzene, G is an organic group containing a fullerene skeleton, the n number of groups each of which is represented by a general formula
R-π-E-CH.sub.2-A-CH.sub.2-E′-
may be the same or different, and at least one π among the n number of π is an arylene group).

A composite material comprising a plurality of polymer chains fixed to a base and swelled with a mixture which contains a salt and a hydrogen bond-donating compound and has a melting point maintained at 100° C. or less.

The invention is directed to a zinc-free lubricating composition for an internal combustion engine containing a phosphorus anti-wear agent, an ashless antioxidant, and a metal-free basic detergent. The lubricating composition provides wear protection, deposit control, and improved acid control with reduced levels of metal-containing additives.

Disclosed is an internal combustion engine lubricating oil composition for reducing corrosion in the engine of a hybrid vehicle. Reduction of corrosion can be determined by the JIS K2246 test method. Also disclosed are methods for using said lubricating oil composition for reducing corrosion in the engine of a hybrid vehicle.

Disclosed is an internal combustion engine lubricating oil composition for reducing corrosion in the engine of a hybrid vehicle. Reduction of corrosion can be determined by the JIS K2246 test method. Also disclosed are methods for using said lubricating oil composition for reducing corrosion in the engine of a hybrid vehicle.

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

C.sub.6H.sub.6-n—[O—R.sup.1—O—CH.sub.2—R.sup.2—CH.sub.2—R.sup.3].sub.n  (1)

(in the formula (1), n is an integer of 2 or 3, R.sup.1 is any one of —CH.sub.2CH.sub.2—, —CH.sub.2CH.sub.2CH.sub.2— and —CH.sub.2CH(OH)CH.sub.2—, R.sup.2 is a perfluoropolyether chain, R.sup.3 is —OCH.sub.2CH(OH)CH.sub.2O(CH.sub.2).sub.mOH (m in the formula is an integer of 2 to 4)).

The present disclosure relates to methods of lubricating an electric or a hybrid-electric transmission using a lubricant including a solvent system with a blend of one or more base oils with a branched diester and one or more poly(meth)acrylate copolymers, transmissions therefor, and lubricating compositions suitable for such applications that exhibit good lubricant properties, good electrical properties, and good cooling efficiency at the same time.

An object is to provide a viscosity index improver composition that is capable of properly regulating the HTHS viscosity in the effective temperature range of a lubricating oil composition to a lower range, and a lubricating oil composition containing the viscosity index improver composition, and the viscosity index improver composition contains a comb-shaped polymer (A) containing a structural unit derived from a macromonomer (α) and a structural unit derived from a particular monomer (A1), the macromonomer (α) having a (meth)acryloyl group at one end, and having a structural unit derived from a monomer (α1) selected from butadiene and hydrogenated butadiene.