The present invention relates to a lubricant comprising a liquid ethylene copolymer which comprises in polymerized form 20 to 60 wt % of ethylene; and at least 20 wt % of an acrylate, which is selected from C1-C22 alkyl (meth)acrylate. It further relates to the liquid ethylene copolymer; and to a method for reducing friction between moving surfaces comprising the step of contacting the surfaces with the lubricant or with the ethylene copolymer.

A sliding material composition comprising a polymer component comprising (A) a high-density polyethylene and (B) an olefin block copolymer; and (C) a silane coupling agent; wherein the Si content is 0.1 to 15% by mass based on the mass of the entire sliding material composition. The sliding material composition has the same level of slidability as a resin to which particles are added.

A sliding material composition comprising a polymer component comprising (A) a high-density polyethylene and (B) an olefin block copolymer; and (C) a silane coupling agent; wherein the Si content is 0.1 to 15% by mass based on the mass of the entire sliding material composition. The sliding material composition has the same level of slidability as a resin to which particles are added.

A lubricating oil composition for industrial gears, including 10 to 90% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 100 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 10% by mass of a liquid random copolymer (B) of ethylene and α-olefin, the liquid random copolymer (B) being prepared by means of a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, the lubricating oil composition for industrial gears having a kinematic viscosity at 40° C. of 100 to 10,000 mm.sup.2/s.

A lubricating oil composition for industrial gears, including 10 to 90% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 100 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 10% by mass of a liquid random copolymer (B) of ethylene and α-olefin, the liquid random copolymer (B) being prepared by means of a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, the lubricating oil composition for industrial gears having a kinematic viscosity at 40° C. of 100 to 10,000 mm.sup.2/s.

A grease composition including 10 to 98% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, 89 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin produced by using a specific catalyst, and 1 to 30% by mass of a thickener (C) (note that the sum total of (A) to (C) is 100% by mass), wherein the lubricant base oil (A) and the copolymer (B) are mixed in such a ratio that the mixture of the lubricant base oil (A) and the ethylene-α-olefin copolymer (B) has a kinematic viscosity at 100° C. of 1 to 500 mm.sup.2/s and a viscosity index of 120 or more.

A grease composition including 10 to 98% by mass of a lubricant base oil (A) having a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, 89 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin produced by using a specific catalyst, and 1 to 30% by mass of a thickener (C) (note that the sum total of (A) to (C) is 100% by mass), wherein the lubricant base oil (A) and the copolymer (B) are mixed in such a ratio that the mixture of the lubricant base oil (A) and the ethylene-α-olefin copolymer (B) has a kinematic viscosity at 100° C. of 1 to 500 mm.sup.2/s and a viscosity index of 120 or more.

A lubricating oil composition for internal combustion engines, including a lubricant base oil and a liquid random copolymer of ethylene and an α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 12.5 mm.sup.2/s or more, but less than 26.1 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 95 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

A lubricating oil composition for internal combustion engines, including a lubricant base oil and a liquid random copolymer of ethylene and an α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 12.5 mm.sup.2/s or more, but less than 26.1 mm.sup.2/s, and wherein the lubricant base oil consists of a mineral oil having a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 95 or more and a pour point of −10° C. or lower, and/or a synthetic oil having a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more and a pour point of −30° C. or lower.

A lubricating oil composition for hydraulic oils including 10 to 99% by mass of a lubricant base oil (A) with a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin prepared using a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, and having a kinematic viscosity at 100° C. of 10 to 300 mm.sup.2/s.