POLYMER COMPOSITIONS HAVING IMPROVED PROPERTIES AS VISCOSITY INDEX IMPROVERS AND USE THEREOF IN LUBRICATING OILS

摘要

Polymer compositions for use as viscosity modifiers comprising at least two ethylene-based copolymer components are provided. The polymer composition comprises (a) a first ethylene-alpha-olefin copolymer and (b) a second ethylene-alpha-olefin copolymer. The first ethylene-alpha-olefin copolymer (a) has an ethylene content from about 60 to about 80 wt % and the second ethylene-alpha-olefin copolymer (b) has an ethylene content of less than about 60 wt %. The first ethylene-alpha-olefin copolymer (a) has a Melt Flow Rate Ratio (MFRR), defined as the ratio of the MFR measured at 230° C./21.6 kg and at 230° C./2.16 kg, of greater than 30 and optionally also has a Melt Flow Rate (MFR) of at least about 1.5 g/10 min, measured by ASTM D 1238 condition L (230° C./2.16 kg). The present disclosure is also directed to lubricant compositions comprising a lubricating basestock and a polymer composition of the present disclosure and is further directed to reducing gelation in the lubricant compositions.