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

Abstract

There are provided a lubricating oil composition for a fluid dynamic bearing, and a HDD motor fabricated using the same. The lubricating oil composition includes an ester base oil and 0.01 to 3.00 parts by weight of an additive relative to 100 parts by weight of the base oil and has a density of 0.900 g/cm 3 or less at 15° C. and a kinetic viscosity of 9.50 cSt or less at 40° C. According to the present invention, the HDD motor is fabricated by using a lubricating oil composition for a fluid dynamic bearing, the lubricating oil composition having advantages such as low viscosity at practical temperature, reduced evaporation loss and enhanced oxidation stability, thereby improving impact resistance and low temperature operational stability of a fluid dynamic motor.

What is claimed is: 
     
         1 . A lubricating oil composition for a fluid dynamic bearing, comprising:
 an ester base oil; and   0.01 to 3.00 parts by weight of an additive with respect to 100 parts by weight of the base oil,   wherein the lubricating oil composition has a density of 0.900 g/cm or less at 15° C. and a kinetic viscosity of 9.50 cSt or less at 40° C.   
     
     
         2 . The lubricating oil composition of  claim 1 , wherein the density of the lubricating oil composition ranges from 0.866 g/cm 3  to 0.900 g/cm 3  at 15° C. 
     
     
         3 . The lubricating oil composition of  claim 1 , wherein the base oil has a viscosity of 2.30 cP or less at 100° C. 
     
     
         4 . The lubricating oil composition of  claim 1 , wherein the additive includes at least one selected from the group consisting of an antioxidant, an abrasion inhibitor, a corrosion inhibitor, an extreme pressure additive, a viscosity modifier, an antistatic agent and a deactivating agent. 
     
     
         5 . The lubricating oil composition of  claim 1 , wherein the additive includes 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) as an antioxidant. 
     
     
         6 . The lubricating oil composition of  claim 1 , wherein the additive includes barium diphenylamine-4-sulfonate as a metal antioxidant. 
     
     
         7 . The lubricating oil composition of  claim 1 , wherein the additive includes tricresyl phosphate as an internal pressure inhibitor. 
     
     
         8 . A HDD motor including a lubricating oil composition for a fluid dynamic bearing, the lubricating oil composition including an ester base oil and 0.01 to 3.00 parts by weight of an additive with respect to 100 parts by weight of the base oil and having a density of 0.900 g/cm or less at 15° C. and a kinetic viscosity of 9.50 cSt or less at 40° C. 
     
     
         9 . The HDD motor of  claim 8 , wherein the density of the lubricating oil composition ranges from 0.866 g/cm 3  to 0.900 g/cm 3  at 15° C. 
     
     
         10 . The HDD motor of  claim 8 , wherein the base oil has a viscosity of 2.30 cP or less at 100° C. 
     
     
         11 . The HDD motor of  claim 8 , wherein the additive includes at least one selected from the group consisting of an antioxidant, an abrasion inhibitor, a corrosion inhibitor, an extreme pressure additive, a viscosity modifier, an antistatic agent and a deactivating agent. 
     
     
         12 . The HDD motor of  claim 8 , wherein the additive includes 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) as an antioxidant. 
     
     
         13 . The HDD motor of  claim 8 , wherein the additive includes barium diphenylamine-4-sulfonate as a metal antioxidant. 
     
     
         14 . The HDD motor of  claim 8 , wherein the additive includes tricresyl phosphate as an internal pressure inhibitor.