Polyalkylene glycol-based wind turbine lubricant compositions

Abstract

A lubricant composition that is especially useful under extreme conditions, such as in wind turbine gearboxes, comprises a mixed feed glycol; a polyol ester; two particular antioxidants; a phosphorus-based extreme pressure additive; a yellow metal passivator; and at least one specified corrosion inhibitor. The composition passes testing according to ASTM D665B even at 168 hours from initiation, and/or the SKF-Emcor Test Method DIN 51802:1990.

1 . A lubricant composition comprising an effective amount of
 (1) a random or block copolymer polyalkylene glycol based on ethylene oxide and propylene oxide, wherein at least 30 percent by weight of the polyalkylene glycol is ethylene oxide units;   (2) a polyol ester;   (3) N-phenyl-1,1,3,3 -tetramethylbutylnaphthalen-1-amine, as a first antioxidant;   (4) an alkylated diphenylamine formed from the reaction product of N-phenyl-benzenamine and 2,4,4-trimethylpentene, or a mixed octylated and butylated diphenylamine, as a second antioxidant;   (5) a phosphorus-based extreme pressure additive;   (6) a yellow metal passivator; and   (7) at least one corrosion inhibitor selected from the group consisting of (a) an amine salt of an aliphatic phosphoric acid ester; (b) an alkenyl succinic acid half ester in mineral oil; (c) an amine salt of an alkyl phosphoric acid combined with a dithiophosphoric acid derivative; (d) a combination of barium dinonylnaphthalene sulfonate and dinonylnaphthalene carboxylate in a hydrotreated naphthenic oil; and (e) combinations thereof.   
     
     
         2 . The lubricant composition of  claim 1  wherein the random or block copolymer polyalkylene glycol contains from 50 weight percent to 85 weight percent ethylene oxide units, the remainder being propylene oxide units. 
     
     
         3 . The lubricant composition of  claim 1  wherein the polyol ester is a pentaerythritol ester of an alkanoic acid. 
     
     
         4 . The lubricant composition of  claim 1  wherein the phosphorus-based extreme pressure additive is selected from a group consisting of isopropylated triaryl phosphates; amine-phosphates; phosphor-thionates; acid phosphates; alkyl phosphates; and combinations thereof. 
     
     
         5 . The lubricant composition of  claim 1  wherein the yellow metal passivator is selected from a group consisting of benzotriazole, tolyltriazole, tolutriazole, mixtures of sodium tolyltriazole and sodium tolutriazole, and combinations thereof. 
     
     
         6 . The lubricant composition of  claim 1  wherein the composition passes ASTM D665B for at least 168 hours after initiation. 
     
     
         7 . The lubricant composition of  claim 1 , wherein the composition passes SKF-Emcor Test Method DIN 51802: 1990 (ISO 11 007) with distilled water and with salt water (0.5 weight percent sodium chloride, based upon total weight of the salt water) with a rating of zero. 
     
     
         8 . A lubricant composition comprising
 (1) 80 percent by weight of a random or block copolymer polyalkylene glycol based on ethylene oxide and propylene oxide, wherein 60 percent by weight is ethylene oxide units and 40 percent by weight is propylene oxide units, having an ISO viscosity grade of 460;   (2) 15 weight percent of a pentaerythritol ester of an alkanoic acid;   (3) 1 weight percent of N-phenyl-1,1,3,3-tetramethylbutylnaphthalen-1-amine, as a first antioxidant;   (4) 1.3 weight percent of an alkylated diphenylamine formed from the reaction product of N-phenyl-benzenamine and 2,4,4-trimethylpentene, as a second antioxidant;   (5) 1.5 weight percent of an isopropylated triaryl phosphate combined with dodecyl phosphate and triphenyl phosphate as an extreme pressure additive;   (6) 0.1 weight percent of tolyltriazole as a yellow metal passivator; and   (7) 0.6 weight percent of at least one amine salt of an aliphatic phosphoric acid ester as a corrosion inhibitor.