Lubricating oil for flon refrigerant

Abstract

A lubricating oil for a flon refrigerant, containing a polyglycol compound having a kinematic viscosity at 40° C. of at least 30 cSt, a viscosity index of at least 150 and a water content of not more than 200 ppm as a main component. The lubricating oil of the present invention has good stability in the presence of a flon refrigerant, does not cause the copper plating phenomenon and has good compatibility with not only flon-11 and flon-12 but also sparingly soluble refrigerants such as hydrogen-containing flon compounds and perfluoroalkane.

What is claimed is:  
     
         1 . A lubricating oil for a flon refrigerant, containing a polyglycol compound having a kinematic viscosity at 40° C. of at least 30 cSt, a viscosity index of at least 150 and a water content of not more than 200 ppm as a main component.  
     
     
         2 . The lubricating oil as claimed in    claim 1    wherein the polyglycol compound is represented by the general formula:  
       R 1 O—R 2  n OR 3   
       (wherein R 1  and R 3  are each hydrogen, an alkyl group having 1 to 20 carbon atoms, or an acyl group, R 2  is a straight or branched alkylene group having 2 to 4 carbon atoms, and n is a number of at least 10).  
     
     
         3 . The lubricating oil as claimed in    claim 1    wherein water content of the polyglycol compound is not more than 100 ppm.  
     
     
         4 . The lubricating oil as claimed in    claim 1    wherein a flon refrigerant is fluorine-containing alkane selected from the group consisting of trichloromonofluoromethane, dichlorodifluoromethane, 1,1-dichloro-2,2,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1-difluoroethane, trifluoromethane, monochlorodifluoromethane, 1,1,1,2,2,2-hexafluoroethane and tetrafluoromethane.