The present invention provides a grease composition or a lubricating oil composition which is capable of effectively preventing hydrogen brittleness-caused peeling from occurring on a rolling surface of a rolling bearing, is excellent in durability in a high temperature and speed operation, and can be used for a long time. A grease-packed bearing (1) has an inner ring (2), an outer ring (3), and a plurality of rolling elements (4). A sealing member (6) for sealing a grease composition (7) is provided at openings (8a) and (8b) disposed at both axial ends of the inner ring (2) and the outer ring (3). The grease composition (7) includes a base grease composed of a base oil and a thickener and an additive added to the base grease. The additive contains at least one compound selected from among plant-derived polyphenolic compounds and compounds formed by decomposition thereof. The above-described compounds include tannin, gallic acid, ellagic acid, chlorogenic acid, caffeic acid, curcumin, quercetin, and quinic acid.

The present invention is able to provide a lubricating oil composition for compression refrigerating machine having excellent thermal/chemical stability even when used for a compression refrigerating machine using a saturated fluorinated hydrocarbon refrigerant having a low carbon number and a low global warming potential, by using a refrigerant containing a saturated fluorinated hydrocarbon having from 1 to 3 carbon atoms, which uses, as a base oil, an oxygen-containing organic compound composed of at least one member selected from a polyoxyalkylene glycol, a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol and a polyvinyl ether, a copolymer of a poly(oxy)alkylene glycol monoether and a polyvinyl ether, and a polyol ester, each having a hydroxyl value of not more than 15 mgKOH/g.

A refrigeration cycle apparatus includes refrigerant circuits in which a high pressure shell compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected; a mixed refrigerant containing 1,1,2-trifluoroethylene and a refrigerant other than 1,1,2-trifluorothylene and circulating through the refrigerant circuits; and a refrigerating machine oil enclosed in the refrigerant circuits and adjusted such that 1,1,2-trifluoroethylene will be more soluble therein than the other refrigerant is.

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.

The present invention provides a refrigerating machine oil comprising: a base oil comprising an ester of a polyhydric alcohol and a fatty acid comprising 20 to 100% by mol of a branched fatty acid having 4 to 9 carbon atoms; and 0.2 to 0.5% by mass of a phenol-based antioxidant based on a total amount of the refrigerating machine oil, and the refrigerating machine oil being used with trifluoroethylene refrigerant.

Compositions, systems and methods for introducing lubricants, and additives, that are designed to work with environmentally friendly refrigerants into vehicle heat management systems including passenger compartment air conditioning (A/C) systems are disclosed. Methods for charging lubricants and specific additives using environmentally desirable (low GWP) refrigerant or refrigerant blend compositions into an environmentally friendly system, such as a system that uses HFO-1234yf, are also disclosed.

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 % C.sub.N 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 mm.sup.2/s.

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 relates to specific derivatives of dimer fatty acids, compositions comprising them and a method to reduce pour points.

A composition for a heat cycle system having less influence over the ozone layer, a low global warming potential, and excellent stability and durability is provided. A heat cycle system using the composition is also provided. The composition contains a working fluid and a phosphoric acid ester. The working fluid contains trifluoroethylene and difluoromethane. An interaction distance (Ra) between the working fluid and the phosphoric acid ester as determined from the Hansen solubility parameters is at most 15.