Oxidative Stable Oil Formulation

Abstract

Oxidation stable oil formulation comprising a base oil composition comprising a mineral-derived naphthenic base oil, a mineral-derived paraffinic base oil, and/or a Fischer-Tropsch derived paraffinic base oil, a copper passivator and at most 0.1 wt % of an organic sulphur or phosphorus anti-wear additive.

1 . An oxidation stable oil formulation comprising a base oil composition comprising a mineral-derived naphthenic base oil, a mineral-derived paraffinic base oil, and/or a Fischer-Tropsch derived paraffinic base oil, a copper passivator and of from 0.001 to less than 0.1 wt % of an organic sulphur or phosphorus based compound as an anti-wear additive. 
   
   
       2 . The formulation according to  claim 1 , wherein the anti-wear additive comprises an organic polysulfide represented by the formula
   R 1 —(S) a —R 2   (I)   wherein:   a is 2, 3, 4 or 5;   R 1  and R 2  are independently selected from the group consisting of optionally substituted or unsubstituted, straight or branched, and saturated or unsaturated C 1 -C 25  hydrocarbon groups.   
   
   
       3 . The formulation according to  claim 2 , wherein R 1  and R 2  are independently selected from the group consisting of substituted or unsubstituted, straight or branched, and aromatic or aliphatic C 4 -C 20 -hydrocarbon groups. 
   
   
       4 . The formulation according to  claim 3 , wherein R 1  and R 2  are independently selected from the group consisting of straight or branched dodecyl and benzyl. 
   
   
       5 . The formulation according to  claim 1 , wherein the content of organic sulphur or phosphorus anti-wear additive in the formulation is less than 800 mg/kg. 
   
   
       6 . The formulation according to  claim 1 , wherein the copper passivator is a compound according to formula (II) or a substituted benzotriazole compound represented by the formula (III) 
     
       
         
         
             
             
         
       
       wherein R 4  may be hydrogen or a group represented by the formula (IV) 
     
     
       
         
         
             
             
         
       
       or by the formula (V) 
     
     
       
         
         
             
             
         
       
       wherein: 
       c is 0, 1, 2 or 3; 
       R 3  is a straight or branched C 1-4  alkyl group; R 5  is a methylene or ethylene group; 
       R 6  and R 7  are hydrogen or the same or different straight or branched alkyl groups of 1-18 carbon atoms, R 8  and R 9  are the same or different alkyl groups of 3-15 carbon atoms. 
     
   
   
       7 . The formulation according to  claim 6 , wherein R 3  is methyl or ethyl and C is 1 or 2. 
   
   
       8 . The formulation according to  claim 1 , wherein the content of the copper passivator additive is between 5 and 1000 mg/kg. 
   
   
       9 . The formulation according to  claim 1 , wherein the formulation has a sulphur content of below 0.5 wt %. 
   
   
       10 . The formulation to  claim 1 , further comprising an anti-oxidant additive. 
   
   
       11 . The formulation according to  claim 10 , wherein the anti-oxidant additive is a phenolic or amine antioxidant. 
   
   
       12 . The formulation according to  claim 11 , wherein the anti-oxidant additive is ditert.-butylated hydroxotoluene. 
   
   
       13 . The formulation according to  claim 1 , wherein the base oil composition comprises at least 80% by weight of a mineral-derived naphthenic base oil. 
   
   
       14 . The formulation according to  claim 1 , wherein the base oil composition comprises at least 80% by weight of a mineral-derived paraffinic base oil. 
   
   
       15 . The formulation according to  claim 1 , wherein the base oil composition comprises at least 80% by weight of a Fischer-Tropsch derived base oil. 
   
   
       16 . The formulation according to  claim 1 , wherein the kinematic viscosity at 40° C. of the base oil composition is between 1 and 4 mm 2 /sec. 
   
   
       17 . The formulation according to  claim 1 , wherein the kinematic viscosity at 40° C. of the base oil composition is between 5 and 15 mm 2 /sec. 
   
   
       18 . A process to prepare a formulation according to  claim 1 , wherein a mixture of the base oil composition and the organic sulphur or phosphorus anti-wear additive is subjected to a clay treatment and wherein the copper passivator is added after performing the clay treatment. 
   
   
       19 . (canceled) 
   
   
       20 . (canceled) 
   
   
       21 . (canceled)