The present invention provides a working fluid composition for a refrigerating machine containing: a refrigerating machine oil containing, as a base oil, a mixed ester of (A) a complex ester synthesized from a polyhydric alcohol such as neopentyl glycol, a polybasic acid having 6 to 12 carbon atoms, a monohydric alcohol having 4 to 18 carbon atoms and the like, and (B) a polyol ester synthesized from a polyhydric alcohol such as neopentyl glycol and a monocarboxylic fatty acid having 4 to 18 carbon atoms, in a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to 95/5; and a refrigerant such as carbon dioxide.

The lubricating base oil of the present invention comprises an ester synthesized from: a first component that is at least one selected from polyhydric alcohols having 2 to 4 hydroxyl groups; a second component that is at least one selected from polybasic acids having 6 to 12 carbon atoms; and a third component that is at least one selected from monohydric alcohols having 4 to 18 carbon atoms and monocarboxylic acids having 2 to 12 carbon atoms. In addition, the refrigerating machine oil and the working fluid composition for a refrigerating machine of the present invention each comprise the above lubricating base oil.

Provided herein are grease compositions comprising at least one estolide compound of formula:

##STR00001##

in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 2; R.sub.1, independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R.sub.2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R.sub.3 and R.sub.4, independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided are methods of making estolide-based grease products.

Provided herein are grease compositions comprising at least one estolide compound of formula:

##STR00001##

in which n is an integer equal to or greater than 0; m is an integer equal to or greater than 2; R.sub.1, independently for each occurrence, is selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; R.sub.2 is selected from hydrogen and optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched; and R.sub.3 and R.sub.4, independently for each occurrence, are selected from optionally substituted alkyl that is saturated or unsaturated, and branched or unbranched. Also provided are methods of making estolide-based grease products.

A method for preparing an estolide compound and an estolide compound prepared thereby are disclosed. The method for preparing an estolide compound includes: converting biomass fat into a fatty acid; separating the fatty acid into a C.sub.16 saturated fatty acid and a C.sub.18 unsaturated fatty acid; preparing a linear internal olefin (LIO); increasing an amount of oleic acid through partial hydrogenation of the C.sub.18 unsaturated fatty acid; synthesizing an estolide polymer through cross metathesis of the oleic acid; capping the C.sub.16 saturated fatty acid onto the estolide polymer; and reacting the estolide polymer with the linear internal olefin.

The present invention relates to a lubricant base stock, a lubricant composition, a method of lubricating an object and the use of a lubricant base stock. The lubricant base stock comprises a first ester which is the reaction product of: a first polyol comprising at least 3 hydroxyl groups; a first mono-carboxylic acid comprising from 4 to 18 carbon atoms; and a poly-carboxylic acid comprising at least 2 carboxyl groups and comprising from 20 to 60 carbon atoms. The lubricant base stock also comprises a second ester which is the reaction product of: a second polyol comprising at least 3 hydroxyl groups; and a second mono-carboxylic acid comprising from 4 to 18 carbon atoms.

The present invention provides a working fluid composition for a refrigerating machine, comprising: a refrigerating machine oil comprising, as a base oil, a mixed ester of (A) a complex ester and (B) a polyol ester, wherein (A) is obtainable by synthesis from a specific polyhydric alcohol, a polybasic acid having 6 to 12 carbon atoms, and a monohydric alcohol having 4 to 18 carbon atoms or a monocarboxylic acid having 4 to 18 carbon atoms, wherein (B) is obtainable by synthesis from a specific polyhydric alcohol and a monocarboxylic acid having 4 to 18 carbon atoms, and wherein a mass ratio of (A)/(B) is 5/95 to 95/5; and difluoromethane used as a refrigerant, and the working fluid composition having a refrigerant dissolved viscosity of 5.5 mm.sup.2/s or more, at a temperature of 80 C. and an absolute pressure of 2.1 MPa.

A production method for a complex polyester composition includes obtaining a complex polyester composition by condensing polyhydric alcohol having three or more hydroxyl groups, a polycarboxylic acid having at least two carboxyl groups and carbon atoms of greater than or equal to 5, and monohydric alcohol having at least one oxyalkylene group in the absence of a solvent, wherein a component having a weight average molecular weight of less than or equal to 2000 in a GPC chart of the complex polyester composition is less than or equal to 43 area %.

The disclosure generally provides branched diester compounds having exceptional low-temperature and flow properties. The disclosure also provides uses of the branched diester compounds in lubricant compositions, for example, as a base oil, and in other applications where their low-temperature and flow properties can be employed beneficially. The disclosure also provides efficient and green methods for making the branched diester compounds.

In certain embodiments, a vegetable oil-based diester (1,6-hexyldioleate) was branched with propanoic acid (C3) using a green synthetic approach involving solvent-free and catalyst-free epoxide ring opening followed by in situ normal esterification. A total of three branched ester derivatives possessing varied numbers of internal protruding branched ester groups and hydroxyl groups were obtained. All of the pure branched derivatives were comprised of mixtures of positional isomers and/or stereoisomers. Differential scanning calorimetry (DSC) showed that regardless of the composition inhomogeneity of each branched derivative, crystallization was suppressed completely in all of the branched compounds, and they all demonstrated glass transitions below 65 C.

Without being bound by any theory, it is believed that this unique thermal behavior is attributed to the internal protruding branched moieties and hydroxyl groups, which dramatically slowed down mass transfer starting with the least branched compound (2-branched derivative). The viscosity of the branched compounds was one order of magnitude larger than that of the starting di ester due to the increased branching and increased resistance to flow associated with hydrogen bonding introduced by the OH groups. Overall, these branched diesters demonstrated superior low temperature and flow properties comparable to existing non-sustainable commercial lubricants and analogous biobased materials which makes them suitable alternatives for use in lubricant formulations particularly in high performance industrial gear and bearing lubricants.

Provided are a lubricant composition in which low friction and low abrasion are compatible in various temperatures and loads, and a manufacturing method of a lubricant composition. A lubricant composition of the present invention contains at least trivalent or more polyol a1; a mixture b1 of at least one of a polymerization reaction mixture of an unsaturated fatty acid having 18 to 22 carbon atoms which contains at least 75 mass % of a divalent carboxylic acid having 36 to 44 carbon atoms or a mixture obtained by performing hydrogenation with respect to the polymerization reaction mixture; and composite ester A containing polyester in which monool c1 represented by General Formula (1) described below is condensed, in which a feed ratio of the number of moles of a hydroxyl group of a1/the number of moles of a carboxylic acid of b1/the number of moles of a hydroxyl group of c1 is 1/1.5 to 2.0/0.7 to 1.5, and a content of the composite ester A is 0.1 to 5 mass % with respect to the total mass of the lubricant composition.

ROHGeneral Formula (1):