LUBRICATING OIL ADDITIVES

摘要

It is known to add polymethacrylates and other polyolefins to lubricating oils to improve their temperature-viscosity properties and lower their pour point. However, the effective treatment with polymethacrylates is expensive and polyolefin additives do not lower the pour point. The present invention seeks to overcome these drawbacks by providing a process for the preparation of lubricating oil additives, which additives comprise a solution in a lubricating oil of a polymer composition prepared from (A) at least one olefin selected from ethylene, prolylene, butylene and isobutylene, and (B) at least one methacrylate ester wherein the alcohol moiety contains 8 to 18 carbon atoms and, if desired at least one further copolymerisable monomer in a minor amount based on the total weight of (B); the polymer composition comprising 20 to 50% by weight of monomer units of (A) and 50 to 80% by weight of monomer units of (B) the polymer composition being present in the said solution in an amount of 20 to 55% by weight of the solution; the process comprising polymerising monomer(s) (B) in a solution in lubricating oil of a homopolymer of copolymer of the said at least one olefin as defined under (A) wherein the initial viscosity of the solution, prior to polymerisation, does not exceed 15,000 centistokes at 100.degree.C, and subsequently adding to the solution a further amount of a homopolymer or copolymer of at least one olefin as defined under (A) which olefin(s) may be the same as or different from to the olefin(s), the homopolymer or copolymers of which was initially present in the solution, the further amount of the homopolymer or copolymer being added in sufficient quantity to provide a polymer composition having the above-defined proportions of monomer units of (A) and (B).