Lubricating oil composition for high-temperature use

Abstract

The present invention relates to a lubricant composition for a high temperature of which the amount evaporated in a thin film at a high temperature is controlled and of which the fluidity is maintained for a long period of time, and it is a lubricant composition for a high temperature which is obtained by mixing a base oil composition comprising (a) 20 to 100% by weight of a specific aromatic ester and (b) 0 to 80% by weight of another base oil with (c) 0.1 to 10% by weight, based on the total amount of the lubricant composition, of an antioxidant.

1. A lubricant composition for a high temperature which is obtained by mixing a base oil composition comprising (a) 20 to 80% by weight of an aromatic ester compound represented by the following general formula (I) 
                 
 (  wherein R 1  represents an alkyl group having 6 to 16 carbon atoms, and n represents an integer of 1 to  6) ,   
 
       and (b) 20 to 80% by weight of another base oil with (c) 0.1 to 10% by weight, based on the total amount of the lubricant composition, of an antioxidant,
 wherein said another base oil includes an α-olefin oligomer, or hydrogenated products thereof,  or an ethylene-α-olefin oligomer, or hydrogenated products thereof  of said ethylene-α- olefin oligomer.    
 
     
     
       2. The lubricant composition for the high temperature as claimed in  claim 1 , wherein the base oil composition comprises (a) 30 to 80% by weight of the aromatic ester compound and (b) 20 to 70% by weight of another base oil. 
     
     
       3. The lubricant composition for the high temperature as claimed in  claim 1 , wherein the aromatic ester compound (a) is one selected from a trimellitic acid alkyl ester and a pyromellitic acid alkyl ester. 
     
     
       4. The lubricant composition for the high temperature as claimed in  claim 1 , wherein said another base oil (b) also includes a polybutene or hydrogenated products thereof. 
     
     
       5. The lubricant composition for the high temperature as claimed in  claim 1 , wherein the antioxidant (c) is one containing sulfur and/or phosphorus in a molecule. 
     
     
       6. The lubricant composition for the high temperature as claimed in  claim 1 , wherein the antioxidant (c) is one selected from a dithiophosphoric acid salt and a thiophosphoric acid ester. 
     
     
       7. The lubricant composition for the high temperature as claimed in  claim 1 , wherein the antioxidant (c) is 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol. 
     
     
       8. The lubricant composition for the high temperature as claimed in  claim 1 , wherein n is 3 or 4. 
     
     
       9. The lubricant composition for the high temperature as claimed in  claim 1 , wherein n is 3. 
     
     
       10. The lubricant composition for the high temperature as claimed in  claim 1 , wherein n is 4. 
     
     
       11. A lubricant composition for a high temperature which is obtained by mixing a base oil composition comprising ( a )    20  to  80   %  by weight of an aromatic ester compound represented by the following general formula  ( I ) 
                   
         wherein R   1    represents an alkyl group having  6  to  16  carbon atoms, and n represents an integer of  3  to  6 , and  ( b )    20  to  80   %  by weight of another base oil with  ( c )    0 . 1  to  10   %  by weight, based on the total amount of the lubricant composition, of an antioxidant,      wherein said another base oil includes an α - olefin oligomer, or hydrogenated products thereof, or an ethylene -α- olefin oligomer, or hydrogenated products thereof.     
     
     
       12. The lubricant composition for the high temperature as claimed in  claim 11 , wherein the base oil composition comprises ( a )    30  to  80   %  by weight of the aromatic ester compound and  ( b )    20  to  70   %  by weight of another base oil.   
     
     
       13. The lubricant composition for the high temperature as claimed in  claim 11 , wherein the aromatic ester compound ( a )  is one selected from a trimellitic acid alkyl ester and a pyromellitic acid alkyl ester.   
     
     
       14. The lubricant composition for the high temperature as claimed in  claim 11 , wherein said another base oil ( b )  also includes a polybutene or hydrogenated products thereof.   
     
     
       15. The lubricant composition for the high temperature as claimed in  claim 11 , wherein the antioxidant ( c )  is one containing sulfur and/or phosphorus in a molecule.   
     
     
       16. The lubricant composition for the high temperature as claimed in  claim 11 , wherein the antioxidant ( c )  is one selected from a dithiophosphoric acid salt and a thiophosphoric acid ester.   
     
     
       17. The lubricant composition for the high temperature as claimed in  claim 11 , wherein the antioxidant ( c )  is  2 , 6   - di - tert - butyl -   4   -(   4 , 6   - bis ( octylthio )-   1 , 3 , 5   - triazin -   2   - ylamino ) phenol.   
     
     
       18. The lubricant composition for the high temperature as claimed in  claim 11 , wherein n is  3  or  4 . 
     
     
       19. The lubricant composition for the high temperature as claimed in  claim 11 , wherein n is  3 . 
     
     
       20. The lubricant composition for the high temperature as claimed in  claim 11 , wherein n is  4 . 
     
     
       21. A lubricant composition for a high temperature which is obtained by mixing a base oil composition comprising ( a )    20  to  80   %  by weight of an aromatic ester compound represented by the following general formula  ( I ) 
                   
         wherein R   1    represents an alkyl group having  6  to  16  carbon atoms, and n represents an integer of  1  to  6 , and  ( b )    20  to  80   %  by weight of another base oil with  ( c )    0 . 1  to  10   %  by weight, based on the total amount of the lubricant composition, of a zinc dithiophosphoric acid salt antioxidant,      wherein said another base oil includes an α - olefin oligomer, or hydrogenated products thereof, or an ethylene -α- olefin oligomer, or hydrogenated products thereof.