Abstract: The present invention provides a lubricating oil composition comprising a lubricating base oil, and at least one ester additive selected from a first ester that is a fatty acid 3,4-epoxycyclohexyl alkyl ester and a second ester that is a 3,4-epoxycyclohexyl carboxylic acid alkyl ester, wherein a content of the ester additive is 0.01 to 5.0% by mass based on the total mass of the lubricating oil composition.

Abstract: A working fluid composition for a refrigerating machine comprises a refrigerant comprising monofluoroethane and a refrigerating machine oil comprising, as a base oil, at least one selected from a mineral oil having % CN in an n-d-M ring analysis of 10 to 60 and a pour point of ?15° C. or lower and a synthetic hydrocarbon oil having a pour point of ?15° C. or lower, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: 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.

Abstract: A working fluid composition for a refrigerating machine comprising: a refrigerating machine oil containing at least one lubricating base oil selected from a mineral oil and a synthetic oil, and at least one phosphorus compound selected from a mono(alkylphenyl) diphenyl phosphate having a C3-C5 alkyl group and a di(alkylphenyl) phenyl phosphate having two C3-C5 alkyl groups, wherein a content of the phosphorus compound is 0.01 to 5% by mass based on a total amount of the refrigerating machine oil; and a hydrocarbon refrigerant having 2 to 4 carbon atoms.

Abstract: The working fluid composition for a refrigerating machine of the present invention comprises a mixed refrigerant comprising a hydrofluoroethane represented by the following formula (A), difluoromethane and tetrafluoropropene, and a refrigerating machine oil comprising at least one selected from a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as a base oil, wherein a carbon/oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less. C2HnF6-n??(A) [n represents 1 or 2.

Abstract: The working fluid composition for a refrigerating machine of the present invention comprises a refrigerant comprising monofluoroethane, and a refrigerating machine oil comprising at least one selected from a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as a base oil, wherein a carbon/oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less.

Abstract: The working fluid composition for a refrigerating machine of the present invention comprises a refrigerant comprising a first refrigerant component and a second refrigerant component, and having a global warming potential (GWP) of 500 or less, wherein the first refrigerant component is at least one selected from difluoromethane and tetrafluoropropene, and the second refrigerant component is at least one selected from carbon dioxide and a hydrocarbon having 3 to 4 carbon atoms; and a refrigerating machine oil comprising at least one selected from a polyol ester, a polyvinyl ether and a polyalkylene glycol compound as a base oil, wherein a carbon/oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less.

Abstract: A refrigerating machine oil composition comprising at least one ester additive selected from tetraesters of pentaerythritol and one selected from fatty acids having 5 to 18 carbon atoms and hexaesters of dipentaerythritol and one selected from fatty acids having 5 to 18 carbon atoms, and a base oil that is an ester other than the ester additive, in which the content of the ester additive is 2 to 20 mass % based on the total amount of the refrigerating machine oil composition, and the kinematic viscosity of the refrigerating machine oil composition at 40° C. is 3 to 500 mm2/s.

Abstract: A working fluid composition for a refrigerating machine of the present invention comprises: a refrigerating machine oil comprising a complex ester as a base oil; and a hydrocarbon refrigerant having 2 to 4 carbon atoms, the complex ester being obtainable by further esterifying, with at least one selected from a monohydric alcohol having 1 to 20 carbon atoms and a fatty acid having 2 to 20 carbon atoms, an ester intermediate obtained by reacting a neopentyl polyol with a dibasic acid, and having an acid value of 0.5 mgKOH/g or less, the refrigerating machine oil having a kinematic viscosity at 100° C. of 2 to 50 mm2/s.

Abstract: The working fluid composition for a refrigerating machine of the present invention comprises: a refrigerating machine oil comprising a mineral oil and an alkylbenzene in a mass ratio, the mineral oil/the alkylbenzene, of 85/15 to 15/85, wherein the mineral oil has a % CN by n-d-M ring analysis of 20 to 60, a pour point of ?15° C. or less and a kinematic viscosity at 40° C. of 1.5 to 15 mm2/s; and a hydrocarbon refrigerant having 2 to 4 carbon atoms, wherein the refrigerating machine oil having a kinematic viscosity at 40° C. of 2 to 12 mm2/s and a flash point of 120° C. or more.

Abstract: A working fluid composition for a refrigerating machine of the invention comprises a refrigerant comprising difluoromethane and an unsaturated fluorinated hydrocarbon wherein a mass of the difluoromethane/the unsaturated fluorinated hydrocarbon is 95/5 to 10/90, and a refrigerating machine oil comprising at least one base oil selected from among polyol esters with a carbon/oxygen molar ratio of 3.2 to 5.8 and polyvinyl ethers with a carbon/oxygen molar ratio of 3.2 to 5.8.