Stabilized blends containing antioxidants

Abstract

The present invention relates to functional fluid compositions containing antioxidants, and specifically stable compositions containing antioxidants with limited solubility in and/or limited compatibility with the functional fluids with which they are used. In particular the present invention deals with functional fluids used in internal combustion engines, such as engine oils, and antioxidants containing a phenolic or benzoic group, where the antioxidant is present in the functional fluid composition at levels that would otherwise cause the composition to be unstable and/or hazy.

We claim: 
     
         1 . A composition comprising:
 (a) a medium comprising a solvent, a functional fluid, or combinations thereof; and   (b) an antioxidant component that is not fully soluble in the medium; and   (c) a stabilizing component that is soluble in (a) and that interacts with (b) such that (b)'s solubility in (a) is improved;   wherein components (b) and (c) are present in component (a) in the form of dispersed particles having an average diameter of less than 10 microns.   
     
     
         2 . The composition of  claim 1  wherein component (b), the antioxidant component, comprises a phenolic antioxidant, an alkylated phenolic antioxidant, a benzyl-amine antioxidant, a phenyl-amine antioxidant, a phenyl-benzyl-amine antioxidant, a naphthyl-amine antioxidant, a phenyl-naphthyl-amine antioxidant, an alkylated phenyl-amine antioxidant, an alkylated phenyl-benzyl-amine antioxidant, an alkylated phenyl-naphthyl-amine antioxidant, or a combination thereof. 
     
     
         3 . The composition of  claim 1  wherein component (b), the antioxidant component, comprises an alkylated diphenyl amine antioxidant, an alkylated phenyl-naphthyl amine antioxidant, a sterically hindered phenolic antioxidant, or combinations thereof. 
     
     
         4 . The composition of  claim 1  wherein component (c), the stabilizing component, comprises: (i) a nitrogen-containing dispersant; (ii) a borated nitrogen-containing dispersant; (iii) an alkyl borate; (iv) a low molecular weight acylated nitrogen compound; (v) a fatty acid derived amine salt of a salicylic acid; or combinations thereof. 
     
     
         5 . The composition of  claim 1  wherein the turbidity of the overall composition is improved, as defined by a lower JTU and/or NTU value compared to the same composition that does not contain (c), the stabilizing component. 
     
     
         6 . The composition of  claim 1  wherein (b), the antioxidant component, comprises a compound containing at least one nitrogen atom, one or more aromatic groups, and at least one hydrocarbyl substituent group. 
     
     
         7 . The composition of  claim 1  wherein component (a), the medium, comprises: (i) a mineral oil; (ii) a polyolefin-based synthetic oil, or a combination thereof. 
     
     
         8 . The composition of  claim 1  wherein component (a), the medium, comprises a functional fluid selected from the group consisting of: gear oils, greases, turbine fluids, transmission oils, hydraulic fluids, engine oils, two cycle oils, metalworking fluids, fuels, oil field or pipeline fluids, or a combination thereof. 
     
     
         9 . The composition of  claim 1  wherein component (c), the stabilizing component, comprises (i) a compound that contains at least one B—O—R group where the R is hydrogen or a hydrocarbyl group; (ii) a borated nitrogen-containing dispersant; or (iii) combinations thereof. 
     
     
         10 . The composition of  claim 1  wherein component (c), the stabilizing component, comprises a quaternary salt comprising the reaction product of:
 (i) at least one compound selected from the group consisting of: (a) the condensation product of a hydrocarbyl-substituted acylating agent and a compound having an oxygen or nitrogen atom capable of condensing with said acylating agent and said condensation product further having a tertiary amino group; (b) a polyalkene-substituted amine having at least one tertiary amino group; and (c) a Mannich reaction product having a tertiary amino group, said Mannich reaction product being prepared from the reaction of a hydrocarbyl-substituted phenol, an aldehyde, and an amine; and 
 (ii) a quaternizing agent suitable for converting the tertiary amino group of compound (i) to a quaternary nitrogen, wherein the quaternizing agent is selected from the group consisting of dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates; hydrocarbyl epoxides in combination with an acid or mixtures thereof. 
 
     
     
         11 . The composition of  claim 1  wherein the concentration of component (b) in the overall composition is at least 10 percent by weight. 
     
     
         12 . The composition of  claim 1  wherein the concentration of component (c) in the overall composition is at least 10 percent by weight. 
     
     
         13 . The composition of  claim 1  wherein the total combined concentration of component (b) and component (c) in the overall composition is at least 20 percent by weight. 
     
     
         14 . A process of preparing a clear and stable composition comprising:
 (a) a medium comprising a solvent, a functional fluid, or combinations thereof; and   (b) an antioxidant component that is not fully soluble in the medium; and   (c) a stabilizing component that is soluble in (a) and that interacts with (b) such that (b)'s solubility in (a) is improved;   said method comprising the steps of:   I. adding components (b) and (c) to component (a);   II. mixing the components so that particles of components (b) and (c) have an average diameter of less than 10 microns.   
     
     
         15 . The process of  claim 13  wherein the clarity of the resulting mixture is improved, as defined by a lower JTU and/or NTU value compared to the same composition that does not contain (c), the stabilizing component.