Food Grade Rotary Screw Compressor Lubricant

Abstract

Embodiments of the invention provide a food grade lubricant, such as one of synthetic or mineral oil origin, which can be used for the lubrication of rotary screw compressors. The lubricant composition can include a blend of incidental food contact authorized ester or a distilled, acetylated monoglyceride. The lubricant composition can also include an incidental food contact authorized polyether polyol having an average molecular weight number greater than about 1500. The blend can be compounded with additives including one or more of antioxidants, corrosion inhibitors, metal passivators, and anti-foam agents that are cleared for incidental food contact.

1 . A food grade lubricant composition for use with a rotary screw compressor, the lubricant composition comprising:
 about 5 to about 95 weight percent of a distilled, acetylated monoglyceride; and   about 95 to about 5 weight percent of at least one of
 a polyglycol with a minimum molecular weight of about 1500; 
 [alpha]-Butyl-omega-hydroxypoly(oxypropylene); 
 [alpha]-Butyl-omega-hydroxypoly(oxyethylene) poly(oxypropylene); and 
 [alpha]-Hydro-omega-hydroxypoly(oxyethylene) poly(oxypropylene). 
   
   
   
       2 . The lubricant composition of  claim 1  wherein the [alpha]-Butyl-omega-hydroxypoly(oxyethylene) poly(oxypropylene) is produced by random condensation of an approximately 1:1 mixture by weight of ethylene oxide and propylene oxide with butanol. 
   
   
       3 . The lubricant composition of  claim 1  wherein the [alpha]-Hydro-omega-hydroxypoly (oxyethylene) poly(oxypropylene) is produced by random condensation of mixtures of ethylene oxide and propylene oxide including about 25 to about 75 percent by weight of ethylene oxide. 
   
   
       4 . The lubricant composition of  claim 1  wherein any polyoxyalkylene glycols include homopolymers. 
   
   
       5 . The lubricant composition of  claim 1  wherein any polyoxyalkylene glycols include random copolymers. 
   
   
       6 . The lubricant composition of  claim 1  wherein any polyoxyalkylene glycols include block copolymers. 
   
   
       7 . The lubricant composition of  claim 1  and further comprising at least one of:
 an effective amount of at least one antioxidant;   an effective amount of at least one ferrous metal corrosion inhibitor;   an effective amount of a cuprous deactivator;   an effective amount of at least one anti-wear/lubricity additive; and   an effective amount of an antifoam agent.   
   
   
       8 . The lubricant composition of  claim 1  and further comprising at least one of:
 about 0.25% to about 2.0% weight percent of an aromatic amine antioxidant;   about 0.25% to about 2.0% weight percent of a phenolic antioxidant;   about 0.05% to about 2.0% weight percent of at least one ferrous metal corrosion inhibitor;   about 0.05% to about 0.10% weight percent of a cuprous metal deactivator;   about 0.25% to about 0.50% weight percent of at least one anti-wear and lubricity additive; and   about 20 parts per million to about 100 parts per million of a dimethylpolysiloxane antifoam additive.   
   
   
       9 . A method of lubricating a rotary screw air compressor wherein the compressor is continuously run for long time intervals without changing out the lubricant which comprises using as the lubricant the composition of  claim 7 . 
   
   
       10 . A method of lubricating a rotary screw air compressor wherein the compressor is continuously run for long time intervals without changing out the lubricant which comprises using as the lubricant the composition of  claim 8 .