Lubricating oil compositions and methods of use

Abstract

This disclosure relates to a method for improving air release and water separation in a lubricating oil. The method involves formulating a composition comprising at least one lubricating oil base stock as a major component, and one or more lubricating oil additives, as a minor component. The one or more lubricating oil additives include a mixture of antifoam agents. The mixture of antifoam agents includes at least one polysiloxane and at least one acrylate polymer. During operation of a lubricating system containing the lubricating oil, release of entrained air in the lubricating oil is improved, as determined by ASTM D-3427-15, and water separation from the lubricating oil is improved, as determined by ASTM D-1401-18b, as compared to release of entrained air and water separation achieved using a lubricating oil containing other than the mixture of antifoam agents. This disclosure also relates to lubricating oils having a mixture of antifoam agents including at least one polysiloxane and at least one acrylate polymer.

What is claimed is: 
     
         1 . A lubricating oil having a composition comprising: at least one lubricating oil base stock as a major component; and one or more lubricating oil additives, as a minor component; wherein the one or more lubricating oil additives comprise a mixture of antifoam agents; wherein the mixture of antifoam agents comprises at least one polysiloxane and at least one acrylate polymer; wherein the polysiloxane has a kinematic viscosity (KV 25 ) less than about 20,000 cSt at 25° C. as determined by ASTM D-445-19; wherein the at least one polysiloxane is present in an amount from about 0.1 to less than about 30 ppm, calculated as content of Si; wherein the at least one acrylate polymer is present in an amount less than about 60 times the amount of the at least one polysiloxane, calculated as content of Si (ppm); wherein, during operation of a lubricating system containing the lubricating oil, release of entrained air in the lubricating oil is improved, as determined by ASTM D-3427-15, and water separation from the lubricating oil is improved, as determined by ASTM D-1401-18b, as compared to release of entrained air and water separation achieved using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         2 . The lubricating oil of  claim 1  wherein, during operation of a lubricating system containing the lubricating oil, the time required for entrained air content to fall to 0.2 volume percent, as determined by ASTM D-3427-15, is reduced at least 5%, as compared to the time required for entrained air content to fall to 0.2 volume percent using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         3 . The lubricating oil of  claim 1  wherein, during operation of a lubricating system containing the lubricating oil, the time required for complete water separation or emulsion reduction to 3 milliliters or less, as determined by ASTM D-1401-18b, is reduced at least 5%, as compared to the time required for complete water separation or emulsion reduction to 3 milliliters or less, using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         4 . The lubricating oil of  claim 1  wherein the polysiloxane has a kinematic viscosity (KV 25 ) less than about 12,500 cSt at 25° C. as determined by ASTM D-445-19. 
     
     
         5 . The lubricating oil of  claim 1  wherein the at least one polysiloxane is present in an amount from about 0.1 to less than about 20 ppm, calculated as content of Si; wherein the at least one acrylate polymer is present in an amount less than about 20 times the amount of the at least one polysiloxane, calculated as content of Si (ppm). 
     
     
         6 . The lubricating oil of  claim 1  wherein the weight ratio of the polysiloxane to the acrylate polymer is from about 5:1 to about 1:5. 
     
     
         7 . The lubricating oil of  claim 1  wherein the polysiloxane is polydimethylsiloxane. 
     
     
         8 . The lubricating oil of  claim 1  wherein the acrylate polymer is selected from the group consisting of a polyacrylate, a polymethacrylate, a dispersant polyacrylate, a dispersant polymethacrylate, and a mixture thereof. 
     
     
         9 . The lubricating oil of  claim 1  wherein the acrylate polymer has a weight average molecular weight from about 4,000 or less to about 150,000 or greater. 
     
     
         10 . The lubricating oil of  claim 1  wherein the one or more lubricating oil additives are selected from the group consisting of an antioxidant, antiwear agent, dispersant, corrosion inhibitor, ionic liquid, antistatic agent, pour point depressant, seal compatibility agent, extreme pressure agent, metal passivator, and one or more metals. 
     
     
         11 . The lubricating oil of  claim 1  wherein the one or more lubricating oil base stocks are present in an amount from about 75 to about 95 weight percent, based on the total weight of the lubricating oil. 
     
     
         12 . The lubricating oil of  claim 1  wherein the one or more lubricating oil additives are present in an amount from about 1 to about 15 weight percent, based on the total weight of the lubricating oil. 
     
     
         13 . A method for improving air release and water separation in a lubricating oil, said method comprising: formulating a composition comprising at least one lubricating oil base stock as a major component, and one or more lubricating oil additives, as a minor component; wherein the one or more lubricating oil additives comprise a mixture of antifoam agents; wherein the mixture of antifoam agents comprises at least one polysiloxane and at least one acrylate polymer; wherein the polysiloxane has a kinematic viscosity (KV 25 ) less than about 20,000 cSt at 25° C. as determined by ASTM D-445-19; wherein the at least one polysiloxane is present in an amount from about 0.1 to less than about 30 ppm, calculated as content of Si; wherein the at least one acrylate polymer is present in an amount less than about 60 times the amount of the at least one polysiloxane, calculated as content of Si (ppm); wherein, during operation of a lubricating system containing the lubricating oil, release of entrained air in the lubricating oil is improved, as determined by ASTM D-3427-15, and water separation from the lubricating oil is improved, as determined by ASTM D-1401-18b, as compared to release of entrained air and water separation achieved using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         14 . The method of  claim 13  wherein, during operation of a lubricating system containing the lubricating oil, the time required for entrained air content to fall to 0.2 volume percent, as determined by ASTM D-3427-15, is reduced at least 5%, as compared to the time required for entrained air content to fall to 0.2 volume percent using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         15 . The method of  claim 13  wherein, during operation of a lubricating system containing the lubricating oil, the time required for complete water separation or emulsion reduction to 3 milliliters or less, as determined by ASTM D-1401-18b, is reduced at least 5%, as compared to the time required for complete water separation or emulsion reduction to 3 milliliters or less, using a lubricating oil containing other than the mixture of antifoam agents. 
     
     
         16 . The method of  claim 13  wherein the polysiloxane has a kinematic viscosity (KV 25 ) less than about 12,500 cSt at 25° C. as determined by ASTM D-445-19 
     
     
         17 . The method of  claim 13  wherein the at least one polydsiloxane is present in an amount from about 0.1 to less than about 20 ppm, calculated as content of Si; wherein the at least one acrylate polymer is present in an amount less than about 20 times the amount of the at least one polysiloxane, calculated as content of Si (ppm). 
     
     
         18 . The method of  claim 13  wherein the weight ratio of the polysiloxane to the acrylate polymer is from about 5:1 to about 1:5. 
     
     
         19 . The method of  claim 13  wherein the polysiloxane is polydimethylsiloxane. 
     
     
         20 . The method of  claim 13  wherein the acrylate polymer is selected from the group consisting of a polyacrylate, a polymethacrylate, a dispersant polyacrylate, a dispersant polymethacrylate, and a mixture thereof. 
     
     
         21 . The method of  claim 13  wherein the acrylate polymer has a weight average molecular weight from about 4,000 or less to about 150,000 or greater. 
     
     
         22 . The method of  claim 13  wherein the one or more lubricating oil additives are selected from the group consisting of an antioxidant, antiwear agent, dispersant, corrosion inhibitor, ionic liquid, antistatic agent, pour point depressant, seal compatibility agent, extreme pressure agent, metal passivator, and one or more metals. 
     
     
         23 . The method of  claim 13  wherein the one or more lubricating oil base stocks are present in an amount from about 75 to about 95 weight percent, based on the total weight of the lubricating oil. 
     
     
         24 . The method of  claim 13  wherein the one or more lubricating oil additives are present in an amount from about 1 to about 15 weight percent, based on the total weight of the lubricating oil.