| 摘要 |
Polymers which may be considered to have been obtained by the polymerization of monoolefinically unsaturated compounds consisting at least partly of monovinyl unsaturated aromatic compounds having an unbranched saturated hydrocarbon chain of at least 18 carbon atoms (such chains being referred to as long hydrocarbon chains) are added to a wax-containing distillate fuel consisting at least partly of a heavy distillate obtained in the distillation at reduced pressure of an atmospheric distillation residue and containing waxes at least a proportion of which have a melting point above 35 DEG C. and a boiling point above 350 DEG C. The polymers generally have an average molecular weight of 1,000-1,000,000 and when added in an amount of 0.001-2.0% by weight are effective in depressing the pour point of the fuel. Suitable polymers have a main chain of carbon atoms which carries at least one long hydrocarbon side chain attached to the main chain either directly or indirectly via one or more other atoms, such as carbon, oxygen, sulphur, nitrogen and phosphorus atoms. Polymers in which this side chain is indirectly attached to the main chain via at least two carbon atoms forming part of an aromatic ring system are preferred. The polymers may be prepared by (a) polymerizing mono-olefinically unsaturated compounds which at least partly consist of monovinyl aromatic compounds having a long hydrocarbon chain such as alkylstyrenes, acylstyrenes, hydroxyalkylstyrenes, alkylcarboxystyrenes, alkyloxystyrenes, alkylamidostyrenes, alkylvinylnaphthalenes and acylivinylnaphthalenes and may be homopolymers or copolymers prepared by copolymerizing vinyl aromatic compounds, vinyl esters of saturated monocarboxylic acids, alkyl esters of unsaturated mono- and dicarboxylic acids, alkyl vinyl ethers and mono-olefins with the aforesaid long hydrocarbon chain compounds; or (b) polymerizing mono-olefinically unsaturated compounds, which at least partly consist of monovinyl aromatic compounds but which, however, have no long hydrocarbon chains, and subsequently introducing long hydrocarbon side chains into the polymer, which may be, for example, a homo- or copolymer of styrene or of a substituted styrene, by, for example, alkylation or acylation. Polar groups may be incorporated in the polymer by adding monomers containing, for example, hydroxyl, carboxyl, acid-anhydride, or nitrogen-containing groups, to the polymerization reaction to give the polymer a dispersant effect. |
