Abstract: The present invention provides a refrigerating machine oil comprising: a lubricating base oil; and 40 mass % or less of a polymer, based on a total amount of the refrigerating machine oil, the polymer having a structural unit represented by the following formula (I) and a weight average molecular weight of from 500 to 100000. [In formula (I), Ra, Rb and Rc each independently represents a hydrogen atom or a hydrocarbon group, and Rd represents an oxygen-containing organic group or a C1-18 hydrocarbon group.

Abstract: The present invention provides a working fluid composition for a refrigerating machine containing: a refrigerating machine oil containing: a first ester that is a polyol ester of dipentaerythritol and at least one fatty acid selected from fatty acids having 4 to 10 carbon atoms, and has a kinematic viscosity at 100° C. of 7.0 mm2/s or more; and a second ester that is a complex ester of a polyhydric alcohol containing at least one selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a polybasic acid having 6 to 12 carbon atoms, and a monohydric alcohol having 4 to 18 carbon atoms or a fatty acid having 4 to 18 carbon atoms; and a refrigerant containing difluoromethane.

Abstract: The present invention provides a refrigerating machine oil comprising a base oil; a sulfide compound; and an orthophosphoric acid ester, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the orthophosphoric acid ester is 0.1 to 5.0% by mass, based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: The present invention provides a refrigerating machine oil containing an ester base oil obtained from pentaerythritol and mixed fatty acids of a fatty acid having 8 carbon atoms and a fatty acid having 9 carbon atoms, wherein a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, of the ester base oil is 1.06 to 1.20, and used with a mildly flammable hydrofluorocarbon refrigerant.

Abstract: The present invention provides a refrigerating machine oil comprising: a lubricating base oil; and 40 mass % or less of a polymer, based on a total amount of the refrigerating machine oil, the polymer having a structural unit represented by the following formula (I) and a weight average molecular weight of from 500 to 100000. [In formula (I), Ra, Rb and Rc each independently represents a hydrogen atom or a hydrocarbon group, and Rd represents an oxygen-containing organic group or a C1-18 hydrocarbon group.

Abstract: The present invention provides a refrigerating machine oil comprising a polyvinylether having a structural unit represented by the following formula (1): wherein R1, R2, and R3 may be the same or different from each other and each represent a hydrogen atom or a hydrocarbon group, R4 represents a divalent hydrocarbon group or an ethereal oxygen-containing divalent hydrocarbon group, R5 represents a hydrocarbon group, m represents an integer of 0 or more, and in the case where m is 2 or more, a plurality of R4 may be the same or different from each other, a number average molecular weight Mn is 500 or more and 2000 or less, a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.10 or more and 1.25 or less, and the refrigerating machine oil is used with a mildly flammable hydrofluorocarbon refrigerant.

Abstract: The present invention provides a working fluid composition for a refrigerating machine containing: a refrigerating machine oil containing: a first ester that is a polyol ester of dipentaerythritol and at least one fatty acid selected from fatty acids having 4 to 10 carbon atoms, and has a kinematic viscosity at 100° C. of 7.0 mm2/s or more; and a second ester that is a complex ester of a polyhydric alcohol containing at least one selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a polybasic acid having 6 to 12 carbon atoms, and a monohydric alcohol having 4 to 18 carbon atoms or a fatty acid having 4 to 18 carbon atoms; and a refrigerant containing difluoromethane.

Abstract: The present invention provides a refrigerating machine oil comprising a base oil; a sulfide compound; and an orthophosphoric acid ester, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the orthophosphoric acid ester is 0.1 to 5.0% by mass, based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: The present invention provides a refrigerating machine oil comprising, as a base oil, at least one oxygen-containing oil having a carbon/oxygen molar ratio of 2.5 or more and 5.8 or less, wherein the refrigerating machine oil is used with a refrigerant comprising 15% by mass or more of difluoromethane, 15% by mass or more of pentafluoroethane, 15% by mass or more of 2,3,3,3-tetrafluoropropene and 15% by mass or more of 1,1,1,2-tetrafluoroethane based on the total amount of the refrigerant.

Abstract: The present invention provides a refrigerating machine oil comprising a base oil; a sulfide compound; and an orthophosphoric acid ester, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the orthophosphoric acid ester is 0.1 to 5.0% by mass, based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: The present invention provides a refrigerating machine oil comprising, as a base oil, at least one oxygen-containing oil having a carbon/oxygen molar ratio of 2.5 or more and 5.8 or less, wherein the refrigerating machine oil is used with a refrigerant comprising 15% by mass or more of difluoromethane, 15% by mass or more of pentafluoroethane, 15% by mass or more of 2,3,3,3-tetrafluoropropene and 15% by mass or more of 1,1,1,2-tetrafluoroethane based on the total amount of the refrigerant.

Abstract: The present invention provides a refrigerating machine oil containing an ester base oil obtained from pentaerythritol and mixed fatty acids of a fatty acid having 8 carbon atoms and a fatty acid having 9 carbon atoms, wherein a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, of the ester base oil is 1.06 to 1.20, and used with a mildly flammable hydrofluorocarbon refrigerant.

Abstract: 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.

Abstract: The present invention provides a refrigerating machine oil comprising a polyvinylether having a structural unit represented by the following formula (1): wherein R1, R2, and R3 may be the same or different from each other and each represent a hydrogen atom or a hydrocarbon group, R4 represents a divalent hydrocarbon group or an ethereal oxygen-containing divalent hydrocarbon group, R5 represents a hydrocarbon group, m represents an integer of 0 or more, and in the case where m is 2 or more, a plurality of R4 may be the same or different from each other, a number average molecular weight Mn is 500 or more and 2000 or less, a ratio of a weight average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.10 or more and 1.25 or less, and the refrigerating machine oil is used with a mildly flammable hydrofluorocarbon refrigerant.

Abstract: 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.

Abstract: The present invention provides a refrigerating machine oil comprising: a base oil; a sulfide compound; and a gallate, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the gallate is 10 to 500 ppm by mass based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: The present invention provides a refrigerating machine oil comprising a base oil; a sulfide compound; and an orthophosphoric acid ester, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the orthophosphoric acid ester is 0.1 to 5.0% by mass, based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

Abstract: The present invention provides a refrigerating machine oil comprising: a base oil; a sulfide compound; and a gallate, wherein a content of the sulfide compound is 0.01 to 2.0% by mass and a content of the gallate is 10 to 500 ppm by mass based on a total amount of the refrigerating machine oil, and the refrigerating machine oil having a kinematic viscosity at 40° C. of 3 to 500 mm2/s.

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 present invention provides a working fluid composition for a refrigerator machine comprising a base oil comprising an ether-based compound, a carbodiimide compound, and an unsaturated fluorinated hydrocarbon refrigerant. The present invention also provides a refrigerating machine oil comprising a base oil containing an ether-based compound and a carbodiimide compound, the refrigerating machine oil being used together with an unsaturated fluorinated hydrocarbon refrigerant.