Lubricating base stock for internal combustion engine oil and composition containing the same

Abstract

The present invention provides a lubricating base stock for internal combustion engine oil consisting essentially of an ester (A) obtained from an ethylene oxide adduct of diol having a neopentyl structure and a saturated aliphatic monocarboxylic acid having 4 to 12 carbon atoms, wherein the ethylene oxide adduct is obtained by adding ethylene oxide to a diol having a neopentyl structure in a ratio of 1 to 4 moles with respect to 1 mol of the diol, wherein the saturated aliphatic monocarboxylic acid is a linear carboxylic acid or a mixture of saturated aliphatic monocarboxylic acids comprising a linear aliphatic monocarboxylic acid in a ratio of at least 50 mol %, and wherein a dynamic viscosity of the ester (A) at 100° C. is 1 to 5 mm 2 /s, a viscosity index of the ester (A) is at least 140, and a total acid value of the ester (A) is 0.5 mg KOH/g or less.

1 . A lubricating base stock for internal combustion engine oil consisting essentially of an ester (A) obtained from an ethylene oxide adduct of diol having a neopentyl structure and a saturated aliphatic monocarboxylic acid having 4 to 12 carbon atoms, 
 wherein the ethylene oxide adduct is obtained by adding ethylene oxide to a diol having a neopentyl structure in a ratio of 1 to 4 moles with respect to 1 mol of the diol,    the saturated aliphatic monocarboxylic acid is a linear carboxylic acid or a mixture of saturated aliphatic monocarboxylic acids comprising a linear aliphatic monocarboxylic acid in a ratio of at least 50 mol %, and    a dynamic viscosity of the ester (A) at 100° C. is 1 to 5 mm 2 /s, a viscosity index of the ester (A) is at least 140, and a total acid value of the ester (A) is 0.5 mg KOH/g or less.    
     
     
         2 . The lubricating base stock of  claim 1 , wherein the mixture of saturated aliphatic monocarboxylic acids comprises a saturated linear aliphatic monocarboxylic acid in a ratio of at least 80 mol %.  
     
     
         3 . A lubricating base stock for internal combustion engine oil consisting essentially of the ester (A) according to  claim 1  and an ester (B) having an average molecular weight that is different from that of the ester (A), 
 wherein the ester (B) is obtained from a neopentyl polyol alkylene oxide adduct and a saturated aliphatic monocarboxylic acid, and  
 a weight ratio of the ester (A) and the ester (B) is 80:20 to 99.9:0.1.  
 
     
     
         4 . An internal combustion engine lubricating oil composition comprising the base stock according to  claim 1  as a main component, 0.05 to 10 wt % of an antioxidant, 0.05 to 10 wt % of a detergent-dispersant, and 0.01 to 30 wt % of a viscosity index improver.  
     
     
         5 . An internal combustion engine lubricating oil composition comprising the base stock according to  claim 3  as a main component, 0.05 to 10 wt % of an antioxidant, 0.05 to 10 wt % of an detergent-dispersant, and 0.01 to 30 wt % of a viscosity index improver.  
     
     
         6 . A lubricating base stock for internal combustion engine oil consisting essentially of the ester (A) according to  claim 2  and an ester (B) having an average molecular weight that is different from that of the ester (A), 
 wherein the ester (B) is obtained from a neopentyl polyol alkylene oxide adduct and a saturated aliphatic monocarboxylic acid, and  
 a weight ratio of the ester (A) and the ester (B) is 80:20 to 99.9:0.1.  
 
     
     
         7 . An internal combustion engine lubricating oil composition comprising the base stock according to  claim 2  as a main component, 0.05 to 10 wt % of an antioxidant, 0.05 to 10 wt % of a detergent-dispersant, and 0.01 to 30 wt % of a viscosity index improver.  
     
     
         8 . An internal combustion engine lubricating oil composition comprising the base stock according to  claim 6  as a main component, 0.05 to 10 wt % of an antioxidant, 0.05 to 10 wt % of an detergent-dispersant, and 0.01 to 30 wt % of a viscosity index improver.