Ester oil is a kind of high-end synthetic lubricating oil that is always popular, but do you know? Ester oil is a kind of synthetic lubricating oil with good comprehensive performance and early development and application. At present, almost all jet engine lubricating oils in the world are used ester oil. The molecules of ester oil contain ester functional group - COOR '. According to the number and position of ester groups in the molecules, ester oil can be divided into diester, polyol ester and compound ester.
Advantages of ester lubricating oil:
In terms of performance, esters>PAO>three types of base oils, such as XHVI, MSDW and VHVI. The low temperature performance is good. The diester with branched alcohol usually has a low freezing point. The freezing point of commonly used sebacic acid ester and azelaic acid ester is below - 60 ° C; The low temperature viscosity of esters of the same type increases with the increase of molecular weight. The low temperature viscosity of esters will increase significantly if the esterification is not complete and some hydroxyl groups exist.
The thermal stability is good. From the point of view of the thermal synthesis temperature alone, the diester oil is generally about 280 degrees, and the alcohol ester exceeds 300 degrees. This is related to its molecular structure. The synthesis temperature of the fully inhibited ester esterified by neopentyl polyol is higher.
Strong sensitivity to additives. It can be well integrated and coordinated with anti-oxidation, anti-wear and other additives. Active adsorption oil film and passive adhesion oil film in work During the lubrication process, the formation of thick oil film between the friction parts of lubricating oil is critical to the lubrication effect, and compounds containing polar groups are more likely to be adsorbed on the friction interface to form an effective ductile oil film.
Defects of ester lubricating oil:
The advantages of ester oil lie in its hydrolytic stability and material compatibility. Ester oil is easy to absorb moisture because it contains polar groups. The stability of polyester to pure water is fairly good, and it is unstable in acid and alkali environment.
Because there are many additives containing phosphorus and sulfur in the engine oil, and there will be fine metal particles worn down during the working process, the additives will produce acidic substances under the metal catalysis, further catalyzing the hydrolysis of esters, and the performance will be greatly reduced. Although this disadvantage can be treated by adding corresponding additives, the ester oil with special additives will inhibit its performance.