High temperature grease compositions

Claim 1

A high temperature grease composition that comprises (a) 80% to 94% of a base fluid that is a dialkyl ester of hydrogenated dimer acids having 32 to 52 carbon atoms and containing less than 8% based on the weight of dimer acids of trimer acids, wherein each alkyl group has 5 to 16 carbon atoms; (b) 0.2% to 6% of an additive system that comprises (i) 0.1% to 2% of an antioxidant component that comprises an aromatic amine selected from the group consisting of secondary amines having the structural formula ##STR5## wherein R' and R" each represents phenyl, alkylphenyl, naphthyl, or alkylnaphthyl; phenothiazine; alkylphenothiazines; alkoxyphenothiazines; alkyl-hydroxybenzylcarbazoles; and mixtures thereof; (ii) 0.08% to 2% of a rust-inhibiting component selected from the group consisting of Group II metal salts, ammonium salts, and amine salts of petroleum sulfonic acids, alkylated naphthalene sulfonic acids, alkenylsuccinic acids, and sorbitan esters of C 10-18 fatty acids; (iii) 0.01% to 1% of a metal-passivating component selected from the group consisting of benzimidazole, benzotriazole, alkylbenzotriazoles, aminobenzotriazoles, methylene bis benzotriazole, the reaction product of benzotriazole with C 12-18 secondary amines and formaldehyde, phenothiazine, naphthotriazole, salicylaldehyde semicarbazone, alkylsalicylaldehyde semicarbazones, C 12-18 fatty acid salts of salicylalaminoguanidine, and mixtures thereof; and (iv) 0.01% to 1% of a load-bearing component selected from the group consisting of Group II metal diorgano dithiophosphates and thiocarbamates, amine salts of partially-esterified phosphoric and chlorophosphonic acids, alkyl mercaptothiadiazoles, aryl phosphates and thiophosphates, chlorinated diphenyls, polyphosphites, and mixtures thereof; and (c) 5% to 20% of a thickener component that contains 4.7% to 19.8% of an oleophilic surface-modified clay and 0.2% to 1% of a dispersant selected from the group consisting of C 2-6 alkylene glycols, fatty acids esters of said glycols, carbonates of said glycols, and lower alkyl ketones, all percentages being percentages by weight based on the weight of the grease composition unless otherwise specified.