Esters from branched-chain acids and neopentylpolyols and phenols as base fluids for synthetic lubricants

Abstract

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.

エステルの自動酸化反応：ポリオールエステル系潤滑油の酸化劣化反応機構の解明に向けて

“…For example, Jensen et al found that hydrogen abstraction reactions on pentaerythrityl tetraheptanoate occur on the acyl groups 30) , particularly at the β and subsequent positions, a result in harmony with the work of Aldrich et al and Sniegoski who also investigated the relative rates of attack on different sites in the ester 31), 32) . Chao et al found that lengthening the chain in pentaerythrityl esters from pentanoate to octanoate reduced the induction period significantly 33) .…”

Esters of methylolcyclohexanols/ones as synthetic base lubricants

“…Lubricants of even greater stability than Type 2 are required for advanced aircraft engines such as those equipped for supersonic transports. Considerable research and development efforts have been carried out to search for lubricants which have better hightemperature characteristics than Type 2 lubricants but are less expensive than Type 3 lubricants (Chao et al, 1983).…”

Esters of oxypropylated trimethylolpropanes as synthetic lubricants

“…The re‐distribution phenomenon which occurs during the synthesis of the ester accounts for this flexibility. This phenomenon, however, is very difficult to define chemically because the analytical methods for determining the equilibrium compositions have been limited to relatively simple mixtures (Edmund, 1976; Chao et al , 1983).…”

“…Lubricants of even greater stability than Type 2 are required for advanced aircraft engines such as those equipped for supersonic transports. Considerable research and development efforts have been carried out to search for lubricants which have better high‐temperature characteristics than Type 2 lubricants but are less expensive than Type 3 lubricants (Chao et al , 1983). Furthermore, polyol esters show appealing tribological characteristics, in particular with respect to boundary and antiwear properties.…”