VISCOSITY MODIFIER FOR LUBRICATING OILS, ADDITIVE COMPOSITION FOR LUBRICATING OILS, AND LUBRICATING OIL COMPOSITIONS

摘要

A viscosity modifier for lubricating oils or an additive composition for lubricating oils, which is excellent in oil -thickening properties and can give lubricating oil compositions excellent in low-temperature characteristics and handleability at low temperature; and lubricating oil compositions excellent in low-temperature characteristics and handleability at low temperature. The viscosity modifier consists of an ethylene/a-olefin copolymer (B) which comprises (i) constituent units derived from ethylene, (ii) constituent units derived from a C<SUB>3-19</SUB> a-olefin, and (iii) constituent units derived from a C<SUB>4-20</SUB> higher a-olefin whose number of carbon atoms is larger than that of the a-olefin forming the units (ii) by at least one and which has the following characteristics (1) and (2): (1) the contents of the units (i), (ii) and (III) are 25-49 mole %, 15 to 55 mole %, and 9 to 40 mole % respectively (with the proviso that the total of the units (i), (ii) and (iii) is 100 mole %) and (2) the limiting viscosity [?] is 0.5 to 5.0 dl/g.