The invention relates to the technology of lubricating oil, and aims at providing a lubricating
oil viscosity index improver. The lubricating
oil viscosity index improver is highly branched
polyethylene with a branching degree of 84-124 branched-chains / 1000 carbons, a
glass transition temperature of -59 DEG C to -67 DEG C, a weight average molecular weight of 64,000-374,000, and a molecular
weight distribution index of 1.7-1.9. According to the invention, the highly branched
polyethylene molecular structure does not contain unsaturated
double bond, and has stable
chemical property,
oxidation resistance and excellent shearing resistance due to a unique topological structure. The branched
polyethylene is adopted as the lubricating
oil viscosity index improver. When the lubricating oil
viscosity index improver is added into lubricating oil
base oil, the highly branched polyethylene has high
solubility in the lubricating oil
base oil, such that in a preparation process, long-time heating is not required, and the preparation process of lubricating oil is simplified; the lubricating oil
viscosity index improver has good thickening performance; the
raw material cost is lower than that of existing
viscosity index improver; the
glass transition temperature of the lubricating oil
viscosity index improver is low, such that
cold resistance is good.