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 medical device, an elastically deformable functional part for a medical device, and a method for sterilizing and/or for establishing sterilization resistance of a medical device or an elastically deformable functional part. The elastically deformable functional part has an openable slit arrangement that widens or opens upon elastic deformation of the elastically deformable functional part and recloses upon cessation of the elastic deformation. The slit wall faces of the slit arrangement are coated with a composition that includes a silicone oil and a thickener.

A medical device, an elastically deformable functional part for a medical device, and a method for sterilizing and/or for establishing sterilization resistance of a medical device or an elastically deformable functional part. The elastically deformable functional part has an openable slit arrangement that widens or opens upon elastic deformation of the elastically deformable functional part and recloses upon cessation of the elastic deformation. The slit wall faces of the slit arrangement are coated with a composition that includes a silicone oil and a thickener.

A grease composition includes a base oil and a thickener. The thickener contains a urea compound and a styrene-based polymer. A content of the styrene-based polymer is 2% by mass or more and 30% by mass or less as to a total amount of the urea compound and the styrene-based polymer. In the thickener, an average value of diameter of particles with a diameter of 0.2 ?m or more is 0.2 ?m or more and 1.0 ?m or less.

A grease composition includes a base oil and a thickener. The thickener contains a urea compound and a styrene-based polymer. A content of the styrene-based polymer is 2% by mass or more and 30% by mass or less as to a total amount of the urea compound and the styrene-based polymer. In the thickener, an average value of diameter of particles with a diameter of 0.2 ?m or more is 0.2 ?m or more and 1.0 ?m or less.

A viscosity index improver containing, in diluent oil, one or more optionally functionalized linear block copolymers having at least one block derived from alkenyl arene covalently linked to at least one block derived from diene in an amount that is greater than the critical overlap concentration (c.sub.h*), in mass %, for the linear block copolymers in the diluent oil; and ester base stock and/or at least one star (or radial) polymer, the star polymer being present in an amount such that the c/c.sub.h* value of the star polymer in the concentrate falls within the range of from 0.01 to about 1.6, wherein c is the concentration in mass % of star polymer in the concentrate and c.sub.h* is the critical overlap concentration in mass % for the star polymer in the diluent oil used to form the concentrate.

A lubricant grease composition is disclosed, the lubricant grease composition including a base oil and a thickener. The thickener includes an aluminum-based complex soap and a polyurea thickener, wherein the lubricant grease is configured for lubrication of surfaces of components in which an upper use temperature of the lubricant grease composition is at least 90 C.

A lubricant grease composition is disclosed, the lubricant grease composition including a base oil and a thickener. The thickener includes an aluminum-based complex soap and a polyurea thickener, wherein the lubricant grease is configured for lubrication of surfaces of components in which an upper use temperature of the lubricant grease composition is at least 90 C.

A method for preparing a final grease product comprising steps of: (a) mixing a polymeric thickener, which comprises a polymer of propylene, and a lubricating base oil at a temperature above the melting point of the polymeric thickener, wherein the polymeric thickener is present in an amount of 11.5-15.5 wt %, based on the total weight of the mixture so obtained; (b) cooling the mixture as obtained in step (a); (c) subjecting the cooled mixture as obtained in step (b) to a first mechanical treatment, to obtain an intermediate grease; (d) subjecting the intermediate grease as obtained in step (c) to a second mechanical treatment, carried out at a temperature in the range of from 50-90 C., to obtain the final grease product. The method can be applied to manufacturing of a grease.

A grease composition includes a base oil and a thickener. The thickener contains a urea compound and a styrene-based polymer. A content of the styrene-based polymer is 2% by mass or more and 30% by mass or less as to a total amount of the urea compound and the styrene-based polymer. In the thickener, an average value of diameter of particles with a diameter of 0.2 m or more is 0.2 m or more and 1.0 m or less.