The present invention is directed to the use of poly(polyisobutylenemethacrylate) as viscosity index improving component in lubricating oil compositions. The invention is further related to lubricating oil compositions comprising poly(polyisobutylenemethacrylate) with enhanced shear stability.

A comb polymer can be used for reducing a Noack evaporation loss of a lubricant composition, especially of an engine oil composition. Application of the comb polymer to the lubricant composition can bring about the desired reduction. The comb polymer can include specified amounts of macromonomer and alkyl acrylates. Resulting lubricant compositions can include the comb polymer.

This invention is directed to intramolecular crosslinked polymer chains, commonly known also as single-chain polymer nanoparticles (SCPNs), with high resistance to mechanochemical bond scission and to uses thereof in solution.

This invention provides a lubricating oil composition for automobile transmission that includes: as low-viscosity base oils: (i) between 45 and 95 mass % of a Fischer-Tropsch synthetic low-viscosity base oil with a 100° C. kinematic viscosity of between 1 mm.sup.2/s and 2 mm.sup.2/s, and between 0 and 25 mass % of other than a Fischer-Tropsch synthetic low-viscosity base oil with a 100° C. kinematic viscosity of between 1 mm.sup.2/s and 2 mm.sup.2/s, and (ii) between 0 and 35 mass % of a base oil wherein the 100° C. kinematic viscosity is greater that 2 mm.sup.2/s and no greater than 5 mm.sup.2/s; and (iii) between 5 and 55 mass % of an olefin polymer or copolymer, as a high-viscosity base oil, wherein the 100° C. kinematic viscosity is between 100 and 800 mm.sup.2/s. A lubricating oil composition for an automatic transmission wherein the 100° C. kinematic viscosity of this composition is between 3.8 and 5.5 mm.sup.2/s, the viscosity index is no less than 190, the flashpoint is no less than 140° C., and the reduction ratio of the 100° C. kinematic viscosity after shear stability testing, at 60° C. for 20 hours, is maintained at no greater than 3%.

A viscosity index improver containing a copolymer (A) whose essential constituent monomer is a monomer (a) having a number average molecular weight of 800 to 4,000 represented by the following formula (1), the copolymer (A) having a solubility parameter in the range of 9.00 to 9.40: ##STR00001##
wherein R.sup.1 is a hydrogen atom or a methyl group; —X.sup.1— is a group represented by —O—, —O(AO).sub.m—, or —NH—, AO is a C2-C4 alkyleneoxy group, m is an integer of 1 to 10, each AO may be the same or different when m is 2 or more, and the (AO).sub.m moieties may be randomly bonded or block-bonded; R.sup.2 is a residue after removal of one hydrogen atom from a hydrocarbon polymer whose essential constituent monomer is butadiene in which the butadiene is present in a proportion of 50% by weight or more based on the weight of R.sup.2, or after removal of one hydrogen atom from a polymer formed by partial hydrogenation of the hydrocarbon polymer; and p represents a number of 0 or 1.

A viscosity index improver comprising a copolymer having a unit (a) derived from a maleimide monomer and a unit (b) derived from a macromonomer, wherein viscosity measured by the following method is 8000 mPa.Math.s or less. Viscosity measurement method: A solution composed of 78 mass % of a Group III base oil (viscosity index: 122, kinematic viscosity at 40° C.: 19.6 mm.sup.2/s) on the American Petroleum Institute (API) classification and 22 mass % of the copolymer is measured with a viscometer (TVB-10 manufactured by Toki Sangyo Co., Ltd., rotor: SPINDLE No. M3, rotation speed: 6 rpm) at 25° C.

A lubricating oil composition includes an ethylene/α-olefin copolymer (A) having 70 to 90 mole % of structural units derived from ethylene and an intrinsic viscosity [η] of 0.3 to 1.0 dl/g.

A bicycle chain lubricant that may be applied as a coating on a bicycle chain is a crystalline solid at ambient temperatures, yet when the chain is in motion the forces around internal components locally transforms the coating to a lubricous fluid. This increases chain efficiency in the drive train and reduces ware by limiting water and dirt access to chain internal components.

The invention relates to a poly alkyl(meth)acrylate polymer comprising a combination of polybutadiene-based monomers having different average molecular weight, lubricant compositions comprising the polymer, a method for manufacturing the polymer and the use of the polymer as a viscosity index improver in a lubricating oil composition.

Provided is a lubricant composition having small shear rate dependence of its apparent viscosity. The lubricant composition includes a perfluoropolyether as a base oil, and fluorine resin particles as a thickener. The lubricant composition further includes a fluorine-containing polymer having a tetrafluoroethylene structure under a state in which the polymer is dissolved in the perfluoropolyether.