Grease and method for softening grease

Abstract

A grease of the invention includes: a base oil containing hydrocarbon; and diurea that is represented by a formula (1) below as a thickener and is in a range from 15 mass % to 25 mass % based on a total amount of a composition, the grease exhibiting a worked penetration in a range from 170 to 295. R 1 NHCONHR 2 NHCONHR 3   (1) In the formula, R 1 and R 3 are mutually different and represent a hydrocarbon group having 6 to 18 carbon atoms; and R 2 is a divalent aromatic hydrocarbon group having 6 to 13 carbon atoms.

1 . A grease comprising:
 a base oil comprising hydrocarbon; and   a diurea of formula (1) as a thickener in a range from 15 mass % to 25 mass % based on a total amount of the grease, the grease exhibiting a worked penetration in a range from 170 to 295,
   R 1 NHCONHR 2 NHCONHR 3    (1)
 
   wherein R 1  and R 3  are mutually different and are each independently a hydrocarbon group having 6 to 18 carbon atoms; and R 2  is a divalent aromatic hydrocarbon group having 6 to 13 carbon atoms.   
     
     
         2 . The grease according to  claim 1 , wherein the worked penetration is from 230 to 265. 
     
     
         3 . The grease according to  claim 1 , wherein the hydrocarbon group is a saturated hydrocarbon group. 
     
     
         4 . The grease according to  claim 3 , wherein the saturated hydrocarbon group is an alkyl group or a cycloalkyl group. 
     
     
         5 . The grease according to  claim 4 , wherein the cycloalkyl group is a cyclohexyl group. 
     
     
         6 . The grease according to  claim 4 , wherein R 1  and R 3  are each independently an octyl group or a cyclohexyl group. 
     
     
         7 . The grease according to  claim 4 , wherein an average ratio of the cycloalkyl group in the diurea is from 15 mol % to 85 mol % based on a total amount of the alkyl group and the cycloalkyl group as functional groups. 
     
     
         8 . The grease according to  claim 7 , wherein the average ratio of the cycloalkyl group is from 15 mol % to 50 mol %. 
     
     
         9 . The grease according to  claim 7 , wherein the average ratio of the cycloalkyl group is from 75 mol % to 85 mol %. 
     
     
         10 . The grease according to  claim 1 , wherein a content of the hydrocarbon is 90 mass % or more based on a total amount of the base oil. 
     
     
         11 . The grease according to  claim 1 , wherein the hydrocarbon is a poly-α-olefin. 
     
     
         12 . The grease according to  claim 1 , wherein a kinematic viscosity at 40 degrees C. of the base oil is 400 mm 2 /s or less. 
     
     
         13 . A softening method of the grease according to  claim 1 , comprising: stirring the grease while applying centrifugal force on the grease.