Why Synthetic Ester? Performance of Synthetic Ester Oil

Synthetic ester oils mainly include diesters, polyol esters, and Complex esters.

 

For example:
Diesters are esters obtained by reacting binary carboxylic acids with monohydric alcohols, or by reacting binary alcohols with monohydric carboxylic acids.
Diesters have two ester groups, and their chemical structure formula is:

 

R 'is the alkyl group of an alcohol, and R is the alkyl group of a dicarboxylic acid.

Performance of Synthetic Ester Oil

 

1. Viscous temperature performance

The viscosity-temperature performance of synthetic ester oil is good, with a high viscosity index, generally exceeding 120 and even reaching 180.

 

For example, Chorus has a synthetic ester Trimethylolpropane Trioleate (TMPTO) Ester Oil with a viscosity index of 169

When the main chain of ester oil molecules becomes longer, the viscosity increases, and the viscosity index also increases; When the main chain structure is the same, molecules with branched chains have higher viscosity, but their viscosity index decreases; When the branched chain contains cyclic structures such as aromatic groups, the viscosity index is lower.

 

2. thermal-oxidation stability

Generally speaking, compared with mineral oils, synthetic ester oils have higher flash points, spontaneous ignition points, thermal decomposition temperatures, and thermal oxidation stability, but they also differ due to their different structures.
Ester oil, as a high-temperature lubricating material, often operates under harsh conditions of high temperature and strong oxidation. Therefore, in actual use, a series of functional additives need to be added

 

Thermal decomposition temperature of ester oils
Esters	Decomposition Temperature (°C)
Methyl octanoate	>193
Glycerol tristearate methyl ester	221
dioctyl sebacate	282
2-ethylhexyl sebacate	284
Neopentyl alcohol dilaurate	322
Trihydroxymethylpropane triheptanyl ester	317
Pentaerythritol tetrahexyl ester	307

3. Lubricity

Due to the easy adsorption of ester oil molecules on the metal surface of the friction pair to form a stable oil film, and the high strength of the formed oil film, the friction coefficient is effectively reduced. Therefore, the lubrication performance of ester oils is generally better than that of mineral oils with the same viscosity

4. Thermal conductivity

The thermal conductivity and specific heat capacity of synthetic ester oil are relatively high, so ester oil works under high temperature conditions and has good heat dissipation, which can effectively reduce the temperature of the friction system.

5. Low toxicity and biodegradability

 

Synthetic ester oils have low toxicity and can generally be considered as non-toxic compounds.
Synthetic ester oils have excellent biodegradability. The biodegradation rate of diesters and polyol esters used for compressor oil can reach over 90%, significantly reducing pollution to the ecological environment.

6. Sensitivity of additives

The sensitivity of additives refers to the sensitivity of the base oil to additives. Adding a small amount of additives can cause significant changes in the performance of the base oil, which is called good sensitivity.
Synthetic ester molecules with polarity have a strong ability to dissolve additive molecules, therefore their sensitivity to additives is good, making it easier to add various additives to improve the comprehensive performance of base oil.