Process for preparing alkyl phenol-sulfur condensate lubricating oil additives

摘要

Additives for improving the low temperature flow properties and oxidative stability of hydrocarbon oils are disclosed, which comprise the alkylation of a phenol in the presence of a dipolar aprotic cosolvent to produce an essentially linear alkylated phenol which is condensated with a sulphurizing agent to produce the low temperature flow improver wherein: (a) the polymer composition has a number average molecular weight of at least about 3,000 and a molecular weight distribution of at least about 1.5; (b) in the alkylated phenol reactant the alkyl groups (i) are essentially linear; (ii) have between 6 and 50 carbon atoms; and (iii) have an average number of carbon atoms between about 12 and 26; and (c) not more than about 10 mole percent of the alkyl groups on the alkylated phenol have less than 12 carbon atoms and not more than about 10 mole percent of the alkyl groups on the alkylated phenol have more than 26 carbon atoms. The additives may also be produced in a branched backbone form in which monomer reactants are copolymerized with certain tri- or tetrafunctional comonomers. Blends of these additives with various hydrocarbon oils, and particularly various middle distillates and lubricating oil compositions, whose low temperature flow properties and oxidative stability are significantly improved thereby, are also disclosed.