Lubricant composition

Abstract

A lubricating oil composition containing a base oil (A) and a thiadiazole-based compound (B). A content of a sulfurized olefin is less than 0.20 mass % based on the total amount of the lubricating oil composition, and a kinematic viscosity of the lubricating oil composition at 100° C. is 2.1 mm2/s or more and less than 5.0 mm2/s.

1 . A lubricating oil composition comprising a base oil (A) and a thiadiazole-based compound (B), wherein
 a content of a sulfurized olefin is less than 0.20 mass % based on the total amount of the lubricating oil composition, and   a kinematic viscosity of the lubricating oil composition at 100° C. is 2.1 mm 2 /s or more and less than 5.0 mm 2 /s.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the component (B) comprises a thiadiazole-based compound (B1) having a branched chain alkyl group. 
     
     
         3 . The lubricating oil composition according to  claim 2 , wherein a number of carbon atoms of the branched chain alkyl group of the component (B1) is 5 or more. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the component (B) comprises a compound represented by any one of the following general formulae (b-1) to (b-4): 
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  are each independently a hydrocarbon group, and m and n are each independently an integer of 1 to 10. 
       
     
     
         5 . The lubricating oil composition according to  claim 4 , wherein R 1  and R 2  are each independently a branched chain alkyl group having 5 or more carbon atoms. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein a content of a compound represented by the following general formula (b-x) is less than 10 mass % based on the total amount of the component (B) contained in the lubricating oil composition, 
       
         
           
           
               
               
           
         
         wherein R a  is a hydrogen atom or a methyl group, R b  is an alkyl group having 1 to 4 carbon atoms, and p is 0 or 1. 
       
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein a content of the component (B) is 0.01 to 3.0 mass % based on the total amount of the lubricating oil composition. 
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein a content of the component (B) is 0.10 to 1.0 mass % based on the total amount of the lubricating oil composition. 
     
     
         9 . The lubricating oil composition according to  claim 1 , wherein the component (A) is one or more selected from mineral oils classified in Group II and Group III of API base oil categories, and synthetic oils. 
     
     
         10 . The lubricating oil composition according to  claim 1 , further comprising one or more phosphorus-based compounds (C) selected from a phosphoric acid ester and a phosphorous acid ester. 
     
     
         11 . The lubricating oil composition according to  claim 10 , wherein the component (C) comprises one or more sulfur-phosphorus-based compounds (C1) selected from a sulfur atom-containing phosphoric acid ester and a sulfur atom-containing phosphorous acid ester. 
     
     
         12 . A speed reducer lubrication composition, comprising the lubricating oil composition according to  claim 1 . 
     
     
         13 . A method of lubricating a speed reducer comprising applying the lubricating oil composition of  claim 1  to the speed reducer. 
     
     
         14 . A method for producing the lubricating oil composition according to  claim 1 , comprising:
 adding the thiadiazole-based compound (B) to the base oil (A), and   preparing the lubricating oil composition in such a manner that the content of the sulfurized olefin is less than 0.20 mass % based on the total amount of the lubricating oil composition, and that   the kinematic viscosity of the lubricating oil composition at 100° C. is 2.1 mm 2 /s or more and less than 5.0 mm 2 /s.