| 摘要 |
A lubricating composition comprises a major proportion of lubricating oil and a minor proportion, sufficient to increase the viscosity index of the composition, of a polymeric product obtained by exposing a homopolymer or copolymer of isobutylene to high-energy ionizing radiation so as to reduce its molecular weight. Isobutylene copolymers mentioned are polymers of isobutylene with isoprene, styrene, vinyl toluene, vinyl ethers, butadiene, maleic anhydride, vinyl trichlorosilane or acrylonitrile. The lubricating oil may be mineral (including hydrogenated or white oils), fatty (including animal, vegetable and fish oils and their polymerized or voltolized products) or synthetic, or mixtures of these. Synthetic oils mentioned are olefin polymers, oils obtained by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products, cracking-coil tar fractions, coal tar or shale oil distillates, esters of mono- or dicarboxylic acids, complex esters, polyglycol esters, halocarbon oils, polysiloxanes, sulphite or carbonate esters, mercaptals and formals. The lubricating composition may contain additional ingredients such as dyes, pour depressors, heat-thickened fatty oils, sulphurized fatty oils, organometallic compounds, soaps, sludge dispersers, foam-suppressing agents, antioxidants, thickeners, other viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized materials (viz. fats, waxes or mineral oils), colloidal solids (e.g. graphite or zinc oxide), solvents and assisting agents (e.g. esters, ketones, alcohols, thioalcohols, amines, aldehydes and halogenated or nitrated compounds). Specific additives mentioned include organic sulphides, phenyl alpha naphthylamine, polymerized lauryl methacrylate, sulphurized wax olefins, tricresyl phosphate, zinc dihexyl dithiophosphate, 2,6-di-tert. butyl-4-methyl-phenol, P2S5-treated calcium nonyl phenol sulphide and the reaction product of phenol with sulphurchloride-treated diisobutylene. The high-energy ionizing radiation used in degrading the isobutylene homopolymer or copolymer may comprise beta rays (e.g. from a van de Graaf electron accelerator), gamma rays or neutrons. The gamma rays may be produced by waste products from an atomic pile, by an atomic pile itself (which may also provide a neutron flux), by naturally occurring radioactive materials (e.g. radium or thorium) or by materials in which radioactivity has been induced by exposure to neutron radiation (e.g. cobalt 60, europium 152 or europium 154). In examples, mineral oil solutions of polyisobutylene or isobutylene/isoprene copolymers are irradiated with gamma rays. The irradiation of isobutylene/styrene copolymers with gamma rays in the absence of a solvent is also mentioned. |
