The invention relates to ester compounds of the general formula (I) ##STR00001##
to a process for preparation thereof and to the use thereof. These ester compounds may contain a mixture of at least two compounds of the general formula (I).

The invention relates to ester compounds of the general formula (I) ##STR00001##
to a process for preparation thereof and to the use thereof. These ester compounds may contain a mixture of at least two compounds of the general formula (I).

A lubricating fluid comprising a base oil, which utilizes carboxylic esters of carboxyl di-end-capped-polyethylene glycols, or a mixture thereof with carboxylic esters of carboxyl di-end-capped-polytetramethylene glycols, to improve low temperature performance, as well as minimize elastohydrodynamic shear strength, and enables the production of high efficiency fluids with enhanced low temperature properties for machines or machine elements that operate in the elastohydrodynamic regime in lubrication.

A lubricating fluid comprising a base oil, which utilizes carboxylic esters of carboxyl di-end-capped-polyethylene glycols, or a mixture thereof with carboxylic esters of carboxyl di-end-capped-polytetramethylene glycols, to improve low temperature performance, as well as minimize elastohydrodynamic shear strength, and enables the production of high efficiency fluids with enhanced low temperature properties for machines or machine elements that operate in the elastohydrodynamic regime in lubrication.

Provided is a lubricating oil composition for air compressors containing a polyalkylene glycol-containing base oil (A) and a rust-preventive agent (B), wherein the content of the polyalkylene glycol is 65.0% by mass or more based on the total amount of the composition. The lubricating oil composition is excellent in oxidation stability and also in rust prevention and storage stability. Also provided are an air compressor lubricating method and an air compressor using the lubricating oil composition.

Provided is a lubricating oil composition for air compressors containing a polyalkylene glycol-containing base oil (A) and a rust-preventive agent (B), wherein the content of the polyalkylene glycol is 65.0% by mass or more based on the total amount of the composition. The lubricating oil composition is excellent in oxidation stability and also in rust prevention and storage stability. Also provided are an air compressor lubricating method and an air compressor using the lubricating oil composition.

A lubricating fluid comprising a base oil, which utilizes carboxylic esters of carboxyl di-end-capped-polyethylene glycols, or a mixture thereof with carboxylic esters of carboxyl di-end-capped-polytetramethylene glycols, to improve low temperature performance, as well as minimize elastohydrodynamic shear strength, and enables the production of high efficiency fluids with enhanced low temperature properties for machines or machine elements that operate in the elastohydrodynamic regime in lubrication.

A lubricating fluid comprising a base oil, which utilizes carboxylic esters of carboxyl di-end-capped-polyethylene glycols, or a mixture thereof with carboxylic esters of carboxyl di-end-capped-polytetramethylene glycols, to improve low temperature performance, as well as minimize elastohydrodynamic shear strength, and enables the production of high efficiency fluids with enhanced low temperature properties for machines or machine elements that operate in the elastohydrodynamic regime in lubrication.

Estolide esters obtainable by esterification of—hydroxycarboxylic acids having 12 to 24 carbon atoms, the hydroxycarboxylic acids comprising unsaturated hydroxycarboxylic acids having a)—monocarboxylic acids with 6 to 22 carbon atoms and—polyols with at least two hydroxy groups or b)—monoalcohols having 8 to 22 carbon atoms and—linear carboxylic acids having at least two carboxyl groups or c)—monocarboxylic acids having 6 to 22 carbon atoms and—monoalcohols having 8 to 22 carbon atoms.

Estolide esters obtainable by esterification of—hydroxycarboxylic acids having 12 to 24 carbon atoms, the hydroxycarboxylic acids comprising unsaturated hydroxycarboxylic acids having a)—monocarboxylic acids with 6 to 22 carbon atoms and—polyols with at least two hydroxy groups or b)—monoalcohols having 8 to 22 carbon atoms and—linear carboxylic acids having at least two carboxyl groups or c)—monocarboxylic acids having 6 to 22 carbon atoms and—monoalcohols having 8 to 22 carbon atoms.