Lubricating oil composition for fluid dynamic bearing and motor for hdd fabricated using the same

Abstract

There are provided a lubricating oil composition for a fluid dynamic bearing and a motor for a hard disk drive (HDD), the lubricating oil composition including, as a base oil, an aliphatic monocarboxylic acid ester having a total of between 16 to 46 carbon atoms, obtained by an esterification reaction of carboxylic acid represented by Chemical Formula 1 below and a primary or a secondary alcohol having between 8 to 38 carbon atoms, and thus, the motor for an HDD is fabricated using the lubricating oil composition for a fluid dynamic bearing having low viscosity, low evaporation loss, and improved oxidation stability at a practicable temperature, thereby preventing a deterioration in product reliability due to long-time use of the motor.

What is claimed is: 
     
         1 . A lubricating oil composition for a fluid dynamic bearing, the lubricating oil composition comprising, as a base oil, an aliphatic monocarboxylic acid ester having a total of between 16 to 46 carbon atoms, obtained by an esterification reaction of carboxylic acid represented by Chemical Formula 1 below and a primary or a secondary alcohol having between 8 to 38 carbon atoms. 
       
         
           
           
               
               
           
         
       
     
     
         2 . The lubricating oil composition of  claim 1 , wherein the aliphatic monocarboxylic acid ester is palmityl ethylhexanoate or cetyl ethylhexanoate. 
     
     
         3 . The lubricating oil composition of  claim 1 , further comprising 0.01 to 2 parts by weight of an oil antioxidant. 
     
     
         4 . The lubricating oil composition of  claim 3 , wherein the oil antioxidant is 2,2′-methylene-bis(4-methyl-6-tert-butylphenol). 
     
     
         5 . The lubricating oil composition of  claim 1 , further comprising 0.01 to 2 parts by weight of a metal antioxidant. 
     
     
         6 . The lubricating oil composition of  claim 5 , wherein the metal antioxidant is barium diphenylamine-4-sulfonate. 
     
     
         7 . The lubricating oil composition of  claim 1 , further comprising 0.01 to 2 parts by weight of an internal pressure inhibitor. 
     
     
         8 . The lubricating oil composition of  claim 7 , wherein the internal pressure inhibitor is tricresyl phosphate. 
     
     
         9 . A motor for a hard disk drive (HDD), the motor comprising a lubricating oil composition for a fluid dynamic bearing, including, as a base oil, an aliphatic monocarboxylic acid ester having a total of between 16 to 46 carbon atoms, obtained by an esterification reaction of carboxylic acid represented by Chemical Formula 1 below and a primary or a secondary alcohol having between 8 to 38 carbon atoms. 
       
         
           
           
               
               
           
         
       
     
     
         10 . The motor of  claim 9 , wherein the aliphatic monocarboxylic acid ester is hexadecan-7-yl-ethylhexanoate. 
     
     
         11 . The motor of  claim 9 , wherein the lubricating oil composition for a fluid dynamic bearing further includes 0.01 to 2 parts by weight of an oil antioxidant. 
     
     
         12 . The motor of  claim 11 , wherein the oil antioxidant is 2,2′-methylene-bis(4-methyl-6-tert-butylphenol). 
     
     
         13 . The motor of  claim 9 , wherein the lubricating oil composition for a fluid dynamic bearing further includes 0.01 to 2 parts by weight of a metal antioxidant. 
     
     
         14 . The motor of  claim 13 , wherein the metal antioxidant is barium diphenylamine-4-sulfonate. 
     
     
         15 . The motor of  claim 9 , wherein the lubricating oil composition for a fluid dynamic bearing further includes 0.01 to 2 parts by weight of an internal pressure inhibitor. 
     
     
         16 . The motor of  claim 15 , wherein the internal pressure inhibitor is tricresyl phosphate.