Defoaming agent and associated methods of use

Abstract

Defoaming agents comprising a silicone oil and silica particulates, lubricating oil compositions comprising the defoaming agent, methods of lubrication using a lubricating oil composition comprising the defoaming agent, and methods of reducing the foaming tendency/stability and/or improving the air release rates of non-aqueous fluids, such as lubricant oils, are provided.

1 . A lubricating oil composition comprising:
 a base oil; and   a defoaming agent comprising (a) a silicone oil and (b) silica particulates.   
     
     
         2 . The lubricating oil composition of  claim 1  wherein the silicone oil comprises polydimethylsiloxane. 
     
     
         3 . The lubricating oil composition of  claim 1  wherein the silica particulates comprise hydrophobic fumed silica. 
     
     
         4 . The lubricating oil composition of  claim 1  wherein the silicone oil comprises polydimethylsiloxane and the silica particulates comprise hydrophobic fumed silica. 
     
     
         5 . The lubricating oil composition of  claim 1  wherein the silicone oil is present in the lubricating oil composition at a concentration of from about 0.1 to 500 ppm. 
     
     
         6 . The lubricating oil composition of  claim 1  wherein the silica particulates are present in the lubricating oil composition at a concentration of from about 0.1 to 500 ppm. 
     
     
         7 . The lubricating oil composition of  claim 1  wherein the silica particulates have a particle size of from about 1 to 1000 nm. 
     
     
         8 . The lubricating oil composition of  claim 1  wherein the base oil is present in an amount of 50 to more than 99.99 wt. %, based on the total weight of the lubricating oil composition. 
     
     
         9 . A method comprising:
 applying a lubricating oil composition comprising a base oil; and a defoaming agent comprising (a) a silicone oil and (b) silica particulates to a surface in relative movement to another surface.   
     
     
         10 . The method of  claim 9  wherein the surface is a surface of a rotating member or a sliding member in a vehicle or industrial machine. 
     
     
         11 . The method of  claim 9  wherein the surface is in an engine, a gear mechanism, a speed-change gearbox, a bearing, a hydraulic apparatus or compression machinery. 
     
     
         12 . The method of  claim 9  wherein the surface is in an internal combustion engine. 
     
     
         13 . A method of decreasing the foaming tendency or foaming stability of a non-aqueous fluid comprising:
 providing a non-aqueous fluid having a first foaming tendency or foaming stability as measured according to ASTM D892; and   adding a defoaming agent comprising a silicone oil and silica to the non-aqueous fluid so as to reduce the first foaming tendency or foaming stability to a second foaming tendency or foaming stability.   
     
     
         14 . The method of  claim 13  wherein the non-aqueous fluid is a lubricating oil. 
     
     
         15 . The method of  claim 13  wherein the silicone oil comprises polydimethylsiloxane. 
     
     
         16 . The method of  claim 13  wherein the silica particulates comprise hydrophobic fumed silica. 
     
     
         17 . A method of improving the air release rate of a non-aqueous fluid comprising:
 providing a non-aqueous fluid having a first air release rate as measured according to ASTM D3427; and   adding a defoaming agent comprising a silicone oil and silica particulates to the non-aqueous fluid so as to increase the first air release rate to a second air release rate by reducing air release time.   
     
     
         18 . The method of  claim 17  wherein the non-aqueous fluid is a lubricating oil. 
     
     
         19 . The method of  claim 17  wherein the silicone oil comprises polydimethylsiloxane. 
     
     
         20 . The method of  claim 17  wherein the silica particulates comprise hydrophobic fumed silica.