Refrigerant composition comprising tetrafluoroethane refrigerant and lubricant having miscibility therewith at low temperature

A method for imparting lubrication properties to a tetrafluoroethane refrigerant for refrigeration equipment, which comprises adding to said refrigerant a lubricant oil which is miscible at temperatures below -10.degree. C. selected from the group consisting of a fluorine-containing compound (I) and a lubricating composition comprising said compound (I) in an amount of at least 25% by weight, based on said lubricating composition, said compound (I) being represented by the formula:

• ##STR112## wherein:
• X is a multiple bond-containing monovalent group selected from:
• (i) a carbonyl-containing group of the formula:
• ##STR113## wherein Y represents a hydroxyl group, an unsubstituted or partially substituted alkoxy group having form 1 to 300 carbon atoms, an unsubstituted or partially substituted aryloxy group having from 6 to 300 carbon atoms, an unsubstituted or partially substituted alkylthio group having from 1 to 300 carbon atoms, an unsubstituted or partially substituted arylthio group having from 6 to 300 carbon atoms, an unsubstituted or partially substituted amino group having from 0 to 300 carbon atoms, an unsubstituted or partially substituted monovalent aliphatic hydrocarbon residue having from 1 to 100 carbon atoms, or an unsubstituted or partially substituted monovalent aromatic hydrocarbon residue having from 6 to 100 carbon atoms;
• p is an integer of from 1 to 3;
• A represents an unsubstituted or partially substituted mono-, bi- or trivalent perfluorocarbon residue having from 1 to 15 carbon atoms, or an unsubstituted or partially substituted mono-, bi- or trivalent perfluoroether residue having from 2 to 15 carbon atoms, or an unsubstituted or partially substituted mono-, bi- or trivalent perfluoropolyether having from 3 to 15 carbon atoms;
• l is an integer of from 1 to 3;
• m is an integer of from 0 to 80;
• m' is 0 or 1;
• and
• n is an integer of from 1 to 4;
• wherein when said p and/or said m is not smaller than 2, the units of ( OC.sub.n F.sub.2n) are the same or different and are not replaced or are replaced with a unit or units of the formula:
• ##STR114## wherein B represents a bivalent perfluorocarbon residue having from 1 to 15 carbon atoms, a bivalent perfluoroether residue having from 2 to 15 carbon atoms, or a bivalent perfluoropolyether residue having form 3 to 15 carbon atoms,
• and X' has the same meaning as defined for X of formula (I), with the proviso that the number of unit or units or ( OC.sub.n F.sub.2n) replaced by a unit or units of the formula (IV) is not greater than 30% of the total number of said units of ( OC.sub.n F.sub.2n);
• and wherein when said p is not smaller than 2, said multiple bond-containing monovalent X group is the same or different.