A working fluid composition for a refrigerating machine, containing: a refrigerant containing trifluoroiodomethane; and a refrigerating machine oil containing a complex ester synthesized from a polyhydric alcohol, a polybasic acid, and at least one selected from a monohydric alcohol and a monocarboxylic fatty acid.

An aspect of the present invention provides a refrigerating machine oil containing an ester-based base oil, at least one epoxy compound selected from an alkyl glycidyl ether and an aryl glycidyl ether, and a phenol-based antioxidant, wherein a content of the epoxy compound is 0.7% by mass or more based on a total amount of the refrigerating machine oil, and the refrigerating machine oil is used with a refrigerant containing trifluoroiodomethane.

The present invention provides a refrigerating machine oil composition comprising an ester-based base oil, an epoxy compound, and a carbodiimide compound, the refrigerating machine oil composition being used with a refrigerant containing a fluoropropene in a refrigerating machine comprising a member containing polyethylene terephthalate and/or a member containing hydrogenated acrylonitrile butadiene rubber.

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 refrigerating machine oil containing a lubricating base oil, a dialkyl hydrogen phosphite having two alkyl groups having 1 to 12 carbon atoms in the molecule, and an epoxy compound.

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 refrigerating machine oil containing a lubricating base oil, a dialkyl hydrogen phosphite having two alkyl groups having 1 to 12 carbon atoms in the molecule, and an epoxy compound.

The present invention discloses with the development of ecofriendly and biodegradable lubricant formulation useful for micro electro mechanical systems and process thereof. The new generation Mineral oil free lubricant formulations were developed by esterification of polyols such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol, and aliphatic di carboxylic acids like adipic and azelaic and with mono alcohol, using heterogeneous catalyst Indion 140 with cation exchange properties. The said formulation has a viscosity in the range of 31 to 47 cSt at 40° C., a high viscosity index of 139-196, pour point of approximately <−39° C. with a multifunctional EP additive of recommended dose of 1.5-4%. These new generation lubricants exhibited excellent biodegradability, a high viscosity index, and a low pour point, a high flash point, good lubricity, good oxidative stability, very good protection, against wear, no evaporation loss, good adherence to metal, corrosion inhibiting characteristics and suitability for use with commercial additives. In addition the products are non toxic to the sewage bacteria.

The present invention discloses with the development of ecofriendly and biodegradable lubricant formulation useful for micro electro mechanical systems and process thereof. The new generation Mineral oil free lubricant formulations were developed by esterification of polyols such as 2,2-dimethyl, 1,3-Propanediol, 2,2-diethyl-1,3-propane diol, and aliphatic di carboxylic acids like adipic and azelaic and with mono alcohol, using heterogeneous catalyst Indion 140 with cation exchange properties. The said formulation has a viscosity in the range of 31 to 47 cSt at 40 C., a high viscosity index of 139-196, pour point of approximately <39 C. with a multifunctional EP additive of recommended dose of 1.5-4%. These new generation lubricants exhibited excellent biodegradability, a high viscosity index, and a low pour point, a high flash point, good lubricity, good oxidative stability, very good protection, against wear, no evaporation loss, good adherence to metal, corrosion inhibiting characteristics and suitability for use with commercial additives. In addition the products are non toxic to the sewage bacteria.

A working fluid filled in a refrigerant circulation system comprising a compressor, a condenser, an expansion mechanism, an evaporator, and an accumulator, the working fluid comprising: a refrigerant; and a refrigerating machine oil, wherein the refrigerant comprises a hydrocarbon refrigerant having 2 to 4 carbon atoms, the refrigerating machine oil has a mixed aniline point of 20 C. or higher and 50 C. or lower and a viscosity index of 110 or more, an amount of the refrigerant dissolved in the working fluid is 40% by mass or less under conditions of a temperature of 80 C. and an absolute pressure of 2.8 MPa, and the refrigerating machine oil has a kinematic viscosity at 10 C. of 200 mm.sup.2/s or more and 3000 mm.sup.2/s or less.