Microencapsulation of lubricant additives

Abstract

Provided is a lubricating oil including a nonpolar lubricating oil base stock as a major component and microcapsules as a minor component. The microcapsules includes (i) a core containing a polar solvent and one or more polar lubricating oil additives having solubility in the polar solvent, and (ii) optionally a shell or membrane enclosing the core. The solubility of the polar lubricating oil additives in the nonpolar lubricating oil base stock is improved as compared to solubility achieved using a lubricating oil containing polar lubricating oil additives in a nonpolar lubricating oil base stock and not containing the microcapsules. A method of improving solubility of polar lubricating oil additives in a nonpolar lubricating oil base stock is also provided. The lubricating engine oils of this disclosure can be useful in automotive, marine, aviation, and industrial engine and machine components.

What is claimed is: 
     
         1 . A lubricating oil comprising a nonpolar lubricating oil base stock as a major component and microcapsules as a minor component; wherein said microcapsules are dispersed in said nonpolar lubricating oil base stock; and wherein said microcapsules comprise (i) a core containing a polar solvent and one or more polar lubricating oil additives having solubility in said polar solvent, and (ii) optionally a shell or membrane enclosing said core; wherein the solubility of the polar lubricating oil additives in the nonpolar lubricating oil base stock is improved as compared to solubility achieved using a lubricating oil containing polar lubricating oil additives in a nonpolar lubricating oil base stock and not containing said microcapsules. 
     
     
         2 . The lubricating oil of  claim 1  wherein the nonpolar lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         3 . The lubricating oil of  claim 1  wherein the one or more polar solvents are selected from the group consisting of glycols, alcohols, esters, ethers, carboxylic acids, amines, and organic compounds containing one or more polar functional groups. 
     
     
         4 . The lubricating oil of  claim 1  wherein the one or more polar lubricating oil additives are selected from the group consisting of dispersants, detergents, corrosion inhibitors, rust inhibitors, metal deactivators, antioxidants, anti-wear agents and/or extreme pressure additives, anti-seizure agents, wax modifiers, viscosity index improvers, viscosity modifiers, fluid-loss additives, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, antifoam agents, and pour point depressants. 
     
     
         5 . The lubricating oil of  claim 1  wherein the nonpolar lubricating oil base stock is present in an amount from 70 weight percent to 95 weight percent, and the microcapsules are present in an amount from 0.1 weight percent to 10 weight percent or greater, based on the total weight of the lubricating oil. 
     
     
         6 . The lubricating oil of  claim 1  wherein the shell or membrane is polymeric. 
     
     
         7 . The lubricating oil of  claim 6  wherein the polymer is selected from the group consisting of polystyrenes, polyesters, polyurethanes, polyamides, polyureas, and copolymers thereof; polyacrylonitriles, vinyl resins and aminoplast resins. 
     
     
         8 . The lubricating oil of  claim 1  wherein the microcapsules have a diameter of between 0.01 μm and 50 μm. 
     
     
         9 . A lubricating oil comprising a nonpolar lubricating oil base stock as a major component and microcapsules as a minor component; wherein said microcapsules are dispersed in said nonpolar lubricating oil base stock; and wherein said microcapsules comprise (i) a core containing a polar solvent and one or more polar lubricating oil additives having solubility in said polar solvent, and (ii) optionally a shell or membrane enclosing said core; wherein surface performance in an engine is improved as compared to surface performance in an engine using a lubricating oil containing polar lubricating oil additives in a nonpolar lubricating oil base stock and not containing said microcapsules. 
     
     
         10 . The lubricating oil of  claim 9  wherein surface performance comprises increasing thickness of a lubricating film at contacts requiring elastohydrodynamic lubrication (EHL) in said engine. 
     
     
         11 . A method of improving solubility of polar lubricating oil additives in a nonpolar lubricating oil base stock, said method comprising providing a lubricating oil comprising a nonpolar lubricating oil base stock as a major component and microcapsules as a minor component; wherein said microcapsules are dispersed in said lubricating oil base stock; wherein said microcapsules comprise (i) a core containing a polar solvent and one or more polar lubricating oil additives having solubility in said polar solvent, and (ii) optionally a shell or membrane enclosing said core; wherein the solubility of the polar lubricating oil additives in the nonpolar lubricating oil base stock is improved as compared to solubility achieved using a lubricating oil containing polar lubricating oil additives in a nonpolar lubricating oil base stock and not containing said microcapsules. 
     
     
         12 . The method of  claim 11  wherein the nonpolar lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         13 . The method of  claim 11  wherein the one or more polar solvents are selected from the group consisting of glycols, alcohols, esters, ethers, carboxylic acids, amines, and organic compounds containing one or more polar functional groups. 
     
     
         14 . The method of  claim 11  wherein the one or more polar lubricating oil additives are selected from the group consisting of dispersants, detergents, corrosion inhibitors, rust inhibitors, metal &activators, antioxidants, anti-wear agents and/or extreme pressure additives, anti-seizure agents, wax modifiers, viscosity index improvers, viscosity modifiers, fluid-loss additives, seal compatibility agents, friction modifiers, lubricity agents, anti-staining agents, chromophoric agents, defoamants, demulsifiers, emulsifiers, densifiers, wetting agents, gelling agents, tackiness agents, colorants, antifoam agents, and pour point depressants. 
     
     
         15 . The method of  claim 11  wherein the nonpolar lubricating oil base stock is present in an amount from 70 weight percent to 95 weight percent, and the microcapsules are present in an amount from 0.1 weight percent to 10 weight percent or greater, based on the total weight of the lubricating oil. 
     
     
         16 . The method of  claim 11  wherein the shell or membrane is polymeric. 
     
     
         17 . The method of  claim 16  wherein the polymer is selected from the group consisting of polystyrenes, polyesters, polyurethanes, polyamides, polyureas, and copolymers thereof; polyacrylonitriles, vinyl resins and aminoplast resins. 
     
     
         18 . A method of improving surface performance of a lubricating oil in an engine lubricated with the lubricating oil, said method comprising using as the lubricating oil a formulated oil comprising a nonpolar lubricating oil base stock as a major component and microcapsules as a minor component; wherein said microcapsules are dispersed in said lubricating oil base stock; wherein said microcapsules comprise (i) core containing a polar solvent and one or more polar lubricating oil additives having solubility in said polar solvent, and (ii) optionally a shell or membrane enclosing said core; wherein surface performance in the engine is improved as compared to surface performance in an engine achieved using a lubricating oil containing polar lubricating oil additives in a nonpolar lubricating oil base stock and not containing said microcapsules. 
     
     
         19 . The method of  claim 18  wherein improving surface performance comprises increasing thickness of a lubricating film at contacts requiring elastohydrodynamic lubrication (EHL) in said engine. 
     
     
         20 . The method of  claim 18  wherein the lubricating oil is used in automotive, marine, aviation, and industrial engine and machine component applications.