Grease copositions

Abstract

A grease composition comprising base oil and as thickener calcium complex soap and lithium soap is disclosed. A higher fatty acid, an aromatic monocarboxylic acid and a lower fatty acid are used as carboxylic acids constituting the calcium complex soap and lithium soap. The grease composition has a high dropping point and excellent shear stability, and exhibits thermal stability and long bearing life.

1 . A grease composition comprising:
 base oil; and   a thickener comprising a lithium-containing calcium complex soap of:   (1) a C18-22 straight-chain, substituted or unsubstituted higher fatty acid,   (2) a substituted or unsubstituted aromatic monocarboxylic acid having a benzene ring, and   (3) a C2-4 straight-chain saturated lower fatty acid.   
     
     
         2 . A grease composition according to  claim 1 , wherein the C18-22 straight-chain higher fatty acid in the lithium-containing calcium complex soap is present in an amount of 3 to 25 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         3 . A grease composition according to  claim 1 , wherein the C18-22 straight-chain higher fatty acid is selected from the group consisting of: stearic acid, oleic acid, 12-hydroxystearic acid, behenic acid, and a combination thereof. 
     
     
         4 . A grease composition according to  claim 1 , wherein the mass ratio (Li/Ca) of the lithium metal content to the calcium metal content in the thickener starting material is 1 part per 100 to 5 parts per 100. 
     
     
         5 . (canceled) 
     
     
         6 . A grease composition according to  claim 1 , wherein the C18-22 straight-chain higher fatty acid in the lithium-containing calcium complex soap is present in an amount of 5 to 20 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         7 . A grease composition according to  claim 1 , wherein the aromatic monocarboxylic acid in the lithium-containing calcium complex soap is present in an amount of 0.5 to 3 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         8 . A grease composition according to  claim 1 , wherein the aromatic monocarboxylic acid in the lithium-containing calcium complex soap is present in an amount of 0.75 to 2.5 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         9 . A grease composition according to  claim 1 , wherein the aromatic monocarboxylic acid is selected from the group consisting of: benzoic acid, p-toluic acid, and a combination thereof. 
     
     
         10 . A grease composition according to  claim 1 , wherein the straight-chain saturated lower fatty acid in the lithium-containing calcium complex soap is present in an amount of 1 to 5 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         11 . A grease composition according to  claim 1 , wherein the straight-chain saturated lower fatty acid in the lithium-containing calcium complex soap is present in an amount of 2 to 4 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         12 . A grease composition according to  claim 1 , wherein the straight-chain saturated lower fatty acid is selected from the group consisting of: acetic acid, butyric acid, and a combination thereof. 
     
     
         13 . A method for preparing a grease composition comprising a lithium-containing calcium complex soap, the method comprising:
 combining a base oil, calcium hydroxide, lithium hydroxide, and the following carboxylic acids:   (1) a C18-22 straight-chain, substituted or unsubstituted higher fatty acid,   (2) a substituted or unsubstituted aromatic monocarboxylic acid having a benzene ring, and   (3) a C2-4 straight-chain saturated lower fatty acid.   
     
     
         14 . The method according to  claim 13 , wherein the C18-22 straight-chain higher fatty acid is present in an amount of 3 to 25 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         15 . The method according to  claim 13 , wherein the C18-22 straight-chain higher fatty acid is selected from the group consisting of: stearic acid, oleic acid, 12-hydroxystearic acid, behenic acid, and a combination thereof. 
     
     
         16 . The method according to  claim 13 , wherein the aromatic monocarboxylic acid is present in an amount of 0.5 to 3 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         17 . The method according to  claim 13 , wherein the aromatic monocarboxylic acid is selected from the group consisting of: benzoic acid, p-toluic acid, and a combination thereof. 
     
     
         18 . The method according to  claim 13 , wherein the straight-chain saturated lower fatty acid is present in an amount of 1 to 5 parts by mass, based on 100 parts by mass of the grease composition. 
     
     
         19 . The method according to  claim 13 , wherein the straight-chain saturated lower fatty acid is selected from the group consisting of: acetic acid, butyric acid, and a combination thereof.