High conductivity fluid for air compressor applications

Abstract

The disclosed technology relates to a lubricant composition containing a polyalkylene glycol in which greater than 50% of the repeating units in the polyalkylene glycol contain an alkylene oxide derived moiety comprising a C4 or greater alkyl group. The lubricant compositions are particularly useful in compressors, such as a reciprocating rotary vane, scroll, or rotary screw air compressor.

1 . A lubricant composition comprising:
 (a) at least one oil of lubricating viscosity, and   (b) at least one C 4  or greater polyalkylene glycol, wherein greater than 50% of the repeating units in said at least one C 4  or greater polyalkylene glycol contain an alkylene oxide derived moiety comprising C 4  or greater alkyl.   
     
     
         2 . The lubricant of  claim 1 , wherein less than 50% of the repeating units in said at least one C 4  or greater polyalkylene glycol contain an alkylene oxide derived moiety comprising at least one C 1 , C 2 , C 3  alkyl group or combinations thereof. 
     
     
         3 . The lubricant of  claim 1 , wherein said C 4  or greater polyalkylene glycol of component (b) is soluble in the oil of lubricating viscosity. 
     
     
         4 . The lubricant of clami  1 , wherein said C 4  or greater polyalkylene glycol of component (b) is present at 5 percent by weight or greater. 
     
     
         5 . The lubricant of  claim 1 , further comprising at least one C 1  to C 3  polyalkylene glycol, wherein greater than 50% of the repeat units in said at least one C 1  to C 3  polyalkylene glycol contains an alkylene oxide derived moiety comprising at least one of a C 1 , C 2 , or C 3  alkyl group or combination thereof. 
     
     
         6 . The lubricant of  claim 5 , wherein the ratio of the at least one C 4  or greater polyalkylene glycol to the at least one C 1  to C 3  polyalkylene glycol is from about 1:1 to about 10:1 by weight. 
     
     
         7 . The lubricant of  claim 1  wherein the oil of lubricating viscosity comprises a mineral oil base oil. 
     
     
         8 . The lubricant of  claim 1  wherein the oil of lubricating viscosity comprises an ester base oil. 
     
     
         9 . The lubricant of  claim 8 , wherein the ester base oil comprises at least one of esters of dicarboxylic acids; esters made from C 5  to C 12  monocarboxylic acids and polyols, C 5  to C 12  monocarboxylic acids and polyol ethers, C 5  to C 12  monocarboxylic acids and vegetable oil esters, or mixtures thereof. 
     
     
         10 . The lubricant of  claim 1  wherein the oil of lubricating viscosity comprises a polymerized and/or interpolymerized olefin base oil. 
     
     
         11 . The lubricant of  claim 10 , wherein the polymerized and/or interpolymerized olefin base oil is a polyalphaolefin base oil 
     
     
         12 . The lubricant of  claim 1 , further comprising (d) other additives. 
     
     
         13 . The lubricant of  claim 12 , wherein the other additive comprises at least one (i) antioxidant, (ii) corrosion inhibitor, (iii) metal deactivator, or (iv) combinations thereof. 
     
     
         14 . The lubricant of  claim 13 , wherein the other additives comprises at least one antioxidant present from about 0.005 to about 5 wt. %. 
     
     
         15 . The lubricant of  claim 13 , wherein other additives comprises at least one corrosion inhibitor present form about 0.005 to about 5 wt. % 
     
     
         16 . The lubricant of  claim 13 , wherein other additives comprises at least one metal deactivator present from about 0.001 to about 0.5 wt. %. 
     
     
         17 . The lubricant of  claim 13 , wherein the lubricant composition comprises from about 0.01 to about 10 wt. % of the at least one C 4  or greater polyalkylene glycol; an additive package comprising from about 0.005 to about 5 wt. % of at least one antioxidant, from about 0.005 to about 5 wt. % of at least one corrosion inhibitor, and from about 0.001 to about 0.5 wt. % of at least one metal deactivator; and
 the balance of at least one base oil.   
     
     
         18 . A method of operating an air compressor comprising lubricating said air compressor with a lubricant composition comprising (a) at least one oil of lubricating viscosity, and (b) at least one C 4  or greater polyalkylene glycol, wherein greater than 50% of the repeating units in said at least one C 4  or greater polyalkylene glycol contain a C 4  or greater alkylene oxide moiety. 
     
     
         19 . A method of maintaining the conductivity of a compressor lubricant through multiple heat cycles, comprising lubricating said air compressor with a lubricant composition comprising (a) at least one oil of lubricating viscosity, and (b) at least one C 4  or greater polyalkylene glycol, wherein greater than 50% of the repeating units in said at least one C 4  or greater polyalkylene glycol contain a C 4  or greater alkylene oxide moiety. 
     
     
         20 . (canceled) 
     
     
         21 . (canceled)