Esters providing greater oxidation resistance than neopentylpolyol esters of straight-chain acids were prepared and evaluated as base fluids for synthetic lubricants. Acids employed included 2,2-, 3,3-, and 4,4dimethylpentanoic acids, 4,4dimethylhexanoic acid, and acids having single branchings. Polyols and phenols employed included trimethylolpropane, pentaerythrltol, resorcinol, and dihydroxybenzophenones. As shown by oxygen absorption test, oxidation resistance of these esters was improved when both hydrogen atoms in a methylene group were replaced by methyl groups. This improvement is substantlated by Erdco bearing head tests showing lower viscosity increase, lower acid number, and reduced deposits. Further improvement in oxidation resistance was seen when the neopentylpolyols were replaced by polyhydric phenols. Esters of 2,2-and 3,3dimethylpentanoic acids with dihydric phenols have induction periods ten times those of Type 2 base fluids. However, most of them are deficient in low-temperature fluidii. Data showing variations of crltical physical properties and oxidation resistance with structure are presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.