| 摘要 |
The lubricating oil composition of the invention comprises a lubricating oil base (A) and a copolymer (B) of ethylene and an alpha-olefin of 3 to 20 carbon atoms. The copolymer (B) of ethylene and an alpha-olefin of 3 to 20 carbon atoms is contained in the composition in an amount of 1 to 20 % by weight and has the following properties: (1) the ethylene content (E) is in the range of 40 to 77 % by weight, (2) the weight-average molecular weight (Mw) in terms of polystyrene, as measured by GPC, is in the range of 80,000 to 400,000, (3) Mw/Mn is not more than 2.4, (4) the melting point (Tm), as measured by DSC, is not higher than 60° C., (5) the ethylene content (E, % by weight) and the melting point (Tm, ° C.), as measured by DSC, satisfy the following relation (I): <paragraph lvl="0"><in-line-formula>3.31xE-186>=Tm (I),</in-line-formula>and (6) the intensity ratio, Salphabeta/Salphaalpha, measured by 13C-NMR spectrum is not more than 0.5.
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