Grease

Abstract

A grease includes abase oil and a thickener. The base oil is poly-α-olefin. The thickener is a soap. A viscous transition stress at 25° C. is 300 Pa or more, and a viscous transition stress at 100° C. is 40 Pa or less. A shear viscosity at 25° C. and at a shear rate of 0.1 s −1 is 1.6×10 6 mPa·s or more, and a shear viscosity at 100° C. and at a shear rate of 10 s −1 is 1.1×10 4 mPa·s or less.

1 . A grease comprising a base oil and a thickener, wherein:
 the base oil is poly-α-olefin;   the thickener is a soap;   a viscous transition stress at 25° C. is 300 Pa or more, and a viscous transition stress at 100° C. is 40 Pa or less; and   a shear viscosity at 25° C. and at a shear rate of 0.1 s −1  is 1.6×10 6  mPa·s or more, and a shear viscosity at 100° C. and at a shear rate of 10 s −1  is 1.1×10 4  mPa·s or less.   
     
     
         2 . The grease according to  claim 1 , wherein:
 the soap is a calcium complex soap;   the calcium complex soap is
 a mixture of Ca(A1)(A1), Ca(A1)(A2), Ca(A1)(A3), Ca(A2)(A2), Ca(A2)(A3), and Ca(A3)(A3) 
 (where A1 is —O(C═O)(CH 2 ) 16 CH 3 , A2 is —O(C═O)(CH 2 ) 9 CH═CH(CH 2 ) 5 CH 3 , and A3 is —O(C═O)(CH 2 ) 14 CH 3 ); and 
   the poly-α-olefin has a kinematic viscosity of 28 to 68 mm 2 /s at 40° C.   
     
     
         3 . The grease according to  claim 2 , wherein a mass of the calcium complex soap with respect to a total of the mass of the calcium complex soap and a mass of the poly-α-olefin is 5 to 15 mass %. 
     
     
         4 . The grease according to  claim 1 , wherein:
 the soap is lithium stearate; and   the poly-α-olefin has a kinematic viscosity of 3 to 33 mm 2 /s at 40° C.   
     
     
         5 . The grease according to  claim 4 , wherein a mass of the lithium stearate with respect to a total of the mass of the lithium stearate and a mass of the poly-α-olefin is 10 to 20 mass %.