Lubricating oil composition

Abstract

Provided is a lubricating oil composition for use in turbomachinery, compressors, hydraulic equipments, or machine tools, which contains a mineral oil (A) and a synthetic oil (B) containing a polyalkylene glycol (B1) and a polyol ester (B2), in which the content of the mineral oil (A) is 5 to 95% by mass based on the total amount of the lubricating oil composition, and which is used in turbomachinery, compressors, hydraulic equipments, or machine tools. The lubricating oil composition is excellent in oxidation stability, has a strong effect of preventing sludge precipitation and has excellent water separability even in use for a long period of time in high-temperature environments.

1 . A lubricating oil composition comprising a mineral oil (A) and a synthetic oil (B) that comprises a polyalkylene glycol (B1) and a polyol ester (B2);
 in which the content of the mineral oil (A) is from 5 to 95% by mass based on the total amount of the lubricating oil composition, and   which is used in turbomachinery, compressors, hydraulic equipments, or machine tools.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the content ratio of the component (B1) to the component (B2) [(B1)/(B2)] is, by mass, from 10/90 to 80/20. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the content ratio of the component (A) to the total content of the component (B1) and the component (B2) [(A)/((B1)±(B2))] is, by mass, from 0.05 to 19.0. 
     
     
         4 . The lubricating oil composition according to  claim 3 , further comprising an antioxidant (C) that comprises an amine-type antioxidant (C1). 
     
     
         5 . The lubricating oil composition according to  claim 4 , wherein the nitrogen atom-equivalent content of the component (C1) is, based on the total amount of the lubricating oil composition, from 50 to 3,000 ppm by mass. 
     
     
         6 . The lubricating oil composition according to  claim 1 , further comprising one or more phosphorus compounds (D) selected from a neutral phosphate (D1), an acid phosphate (D2), an acid phosphate amine salt (D3) and a sulfur-phosphorus compound (D4). 
     
     
         7 . The lubricating oil composition according to  claim 6 , wherein the phosphorus atom-equivalent content of the component (D) is, based on the total amount of the lubricating oil composition, from 10 to 1,600 ppm by mass. 
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein the metal atom content is, based on the total amount of the lubricating oil composition, less than 100 ppm by mass. 
     
     
         9 . The lubricating oil composition according to  claim 1 , wherein, when the lubricating oil composition is tested in a water separability test at a temperature of 54° C. according to JIS K2520, the demulsibility degree that indicates a time to be taken for an emulsion layer to reach 3 mL is 15 minutes or less. 
     
     
         10 . A method of using a lubricating oil composition, using the lubricating oil composition of  claim 1  in turbomachinery, compressors, hydraulic equipments, or machine tools.