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 obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a C6-C12 polybasic acid, and a C4-C18 monohydric alcohol or a C4-C18 monocarboxylic fatty acid, and (B) a polyol ester obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol, and a C4-C18 monocarboxylic fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to 95/5; and a hydrocarbon refrigerant having 3 or 4 carbon atoms, wherein a refrigerant dissolved viscosity, at a temperature of 80° C. and an absolute pressure of 1.5 MPa, is 1.0 mm.sup.2/s or more.

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 obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a C6-C12 polybasic acid, and a C4-C18 monohydric alcohol or a C4-C18 monocarboxylic fatty acid, and (B) a polyol ester obtainable by synthesis of from at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol, and a C4-C18 monocarboxylic fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to 95/5; and tetrafluoropropene as a refrigerant, wherein a refrigerant dissolved viscosity, at a temperature of 80° C. and an absolute pressure of 1.6 MPa, is 1.5 mm.sup.2/s or more.

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 obtainable by synthesis of at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane and pentaerythritol, a C6-C12 polybasic acid, and a C4-C18 monohydric alcohol or a C4-C18 monocarboxylic fatty acid, and (B) a polyol ester obtainable by synthesis of from at least one polyhydric alcohol selected from neopentyl glycol, trimethylolpropane, pentaerythritol and dipentaerythritol, and a C4-C18 monocarboxylic fatty acid, in a mass ratio of (A) the complex ester/(B) the polyol ester of 5/95 to 95/5; and tetrafluoropropene as a refrigerant, wherein a refrigerant dissolved viscosity, at a temperature of 80° C. and an absolute pressure of 1.6 MPa, is 1.5 mm.sup.2/s or more.

A rolling bearing that can prevent peeling on a surface of an iron-based metal member by hydrogen brittleness even under a severe environment is provided. The rolling bearing 1 has plural bearing elements formed of an iron-based metal, and a lubricant composition 7 that lubricates metal contact surfaces of the respective bearing elements, the lubricant composition 7 is a grease containing a base oil and alkanolamine and being free of alkali metal salts and alkaline earth metal salts of inorganic acids, the base oil is at least one oil selected from alkyl diphenyl ether oils, poly-α-olefin oils and ester oils, and the alkanolamine is contained by 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the base oil and a thickener.

A rolling bearing that can prevent peeling on a surface of an iron-based metal member by hydrogen brittleness even under a severe environment is provided. The rolling bearing 1 has plural bearing elements formed of an iron-based metal, and a lubricant composition 7 that lubricates metal contact surfaces of the respective bearing elements, the lubricant composition 7 is a grease containing a base oil and alkanolamine and being free of alkali metal salts and alkaline earth metal salts of inorganic acids, the base oil is at least one oil selected from alkyl diphenyl ether oils, poly-α-olefin oils and ester oils, and the alkanolamine is contained by 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of the base oil and a thickener.

A lubricating oil composition including: a lubricating base oil; (A) a first defoaming agent, the first defoaming agent being (A1) a first polymer, or (A2) a second polymer, or any combination thereof; and (B) a second defoaming agent, the second defoaming agent being a silicone defoaming agent, the (A1) first polymer including: a first polymer chain including a polysiloxane structure, the polysiloxane structure having a polymerization degree of 5 to 2000 and being represented by the following general formula (1); and a second polymer chain bonded with the first polymer chain, the second polymer chain including a repeating unit represented by the following general formula (2), the (A2) second polymer being a copolymer of a first monomer component and a second monomer component, the first monomer component represented by the general formula (7) or (8), the second monomer component represented by the general formula (9).

##STR00001##

A lubricating oil composition including: a lubricating base oil; (A) a first defoaming agent, the first defoaming agent being (A1) a first polymer, or (A2) a second polymer, or any combination thereof; and (B) a second defoaming agent, the second defoaming agent being a silicone defoaming agent, the (A1) first polymer including: a first polymer chain including a polysiloxane structure, the polysiloxane structure having a polymerization degree of 5 to 2000 and being represented by the following general formula (1); and a second polymer chain bonded with the first polymer chain, the second polymer chain including a repeating unit represented by the following general formula (2), the (A2) second polymer being a copolymer of a first monomer component and a second monomer component, the first monomer component represented by the general formula (7) or (8), the second monomer component represented by the general formula (9).

##STR00001##

A lubricating oil composition for hydraulic oils including 10 to 99% by mass of a lubricant base oil (A) with a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin prepared using a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, and having a kinematic viscosity at 100° C. of 10 to 300 mm.sup.2/s.

A lubricating oil composition for hydraulic oils including 10 to 99% by mass of a lubricant base oil (A) with a kinematic viscosity at 100° C. of 1 to 14 mm.sup.2/s, a viscosity index of 100 or more, and a pour point of 0° C. or lower, and 90 to 1% by mass of a liquid random copolymer (B) of ethylene and α-olefin prepared using a specific catalyst, wherein the total amount of (A) and (B) is 100% by mass, and having a kinematic viscosity at 100° C. of 10 to 300 mm.sup.2/s.

A lubricating oil composition for automobile transmissions including a lubricant base oil, and a liquid random copolymer of ethylene and α-olefin, the liquid random copolymer being produced using a specific catalyst, wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 4.0 to 7.5 mm.sup.2/s, and a Brookfield viscosity at −40° C. of 20,000 mPa.Math.s or less, and wherein the lubricant base oil consists of a mineral oil with a kinematic viscosity at 100° C. of 2 to 10 mm.sup.2/s, a viscosity index of 105 or more, and a pour point of −10° C. or lower, and/or a synthetic oil with a kinematic viscosity at 100° C. of 1 to 10 mm.sup.2/s, a viscosity index of 120 or more, and a pour point of −30° C. or lower.