Highly esterified oligosaccharide polyester lubricant for machinery

Abstract

A method is provided for reducing friction between at least two metal surfaces which are in a frictional relationship with each other or otherwise in need of lubrication. The method includes contacting the metal surfaces with an effective amount of a lubricant composition comprised of partially-esterified sucrose molecules having, in one embodiment, an average distribution of from 5 to 7 fatty acids bound to a sucrose backbone. The lubricant may also include from about 20 ppm to about 10,000 ppm of an antioxidant, about half of which may be an active tocopherol.

1 . A lubricating composition for lubricating at least two metal surfaces which are in a frictional relationship, the lubricating composition comprising a mixture of: (1) a partially-esterified oligosaccharide; and (2) an effective amount of an antioxidant for reducing oxidation of the partially-esterified oligosaccharide. 
   
   
       2 . The lubricating composition recited in  claim 1  wherein the partially-esterified oligosaccharide comprises a sucrose backbone having an average distribution of bound fatty acids from 5 to 7. 
   
   
       3 . The lubricating composition recited in  claim 2  wherein the partially-esterified sucrose molecules have an average distribution of 6 to 7 fatty acids bound thereto. 
   
   
       4 . The lubricating composition recited in  claim 2  wherein each fatty acid bound to the sucrose backbone has from 2 to 28 carbon atoms in unbranched or branched chains. 
   
   
       5 . The lubricating composition recited in  claim 1  comprising from about 20 to about 10,000 ppm of the antioxidant. 
   
   
       6 . The lubricating composition recited in  claim 1  wherein the antioxidant is selected from the group consisting of tocopherols, alkylated monophenols, alkylthiomethylphenols, alkylidenebisphenols, hydroxylated thiodiphenyl ethers, hydroquinones and alkylated hydroquinones, hydroxybenzylated malonates, benzyl compounds, aromatic hydroxybenzyl compounds, triazine compounds, benzyl phosphonates, acylaminophenols, ascorbic acid, certain esters, and aminic antioxidants and mixtures thereof. 
   
   
       7 . The lubricating composition recited in  claim 6  wherein at least half of the antioxidant is an active tocopherol. 
   
   
       8 . The lubricating composition recited in  claim 1  wherein the partially-esterified sucrose molecules have an average distribution of about 6 fatty acids bound thereto, the fatty acids are branched or unbranched chains each having from 4 to 28 carbon atoms and at least half of the antioxidant is an active tocopherol. 
   
   
       9 . A method of reducing friction between at least two metal surfaces which are in a frictional relationship with each other comprising the step of contacting the metal surfaces with an effective amount of a lubricant composition comprising partially-esterified oligosaccharide molecules. 
   
   
       10 . The method recited in  claim 9  wherein the partially-esterified oligosaccharide molecule comprises a sucrose backbone having an average distribution of from 5 to 7 fatty acids bound thereto. 
   
   
       11 . The method recited in  claim 10  wherein each fatty acid bound to the sucrose backbone has from 2 to 28 carbon atoms in unbranched or branched chains. 
   
   
       12 . The method recited in  claim 11  wherein the fatty acids bound to the sucrose backbone have from 4 to 22 carbon atoms in unbranched or branched chains. 
   
   
       13 . The method recited in  claim 10  wherein said partially-esterified sucrose molecules have an average distribution of 6 to 7 fatty acids bound thereto. 
   
   
       14 . The method recited in  claim 13  wherein said partially-esterified sucrose molecules having an average distribution of about six fatty acids bound thereto. 
   
   
       15 . The method recited in  claim 9  wherein the lubricant further comprises an amount of an antioxidant effective for reducing the rate of oxidation of the lubricant. 
   
   
       16 . The method recited in  claim 15  wherein the lubricant from about 20 to about 10,000 ppm of an antioxidant. 
   
   
       17 . The method recited in  claim 15  wherein the antioxidant is selected from the group consisting of tocopherols, alkylated monophenols, alkylthiomethylphenols, alkylidenebisphenols, hydroxylated thiodiphenyl ethers, hydroquinones and alkylated hydroquinones, hydroxybenzylated malonates, benzyl compounds, aromatic hydroxybenzyl compounds, triazine compounds, benzyl phosphonates, acylaminophenols, ascorbic acid, certain esters, and aminic antioxidants and mixtures thereof. 
   
   
       18 . The method recited in  claim 17  wherein at least half of the antioxidant is an active tocopherol. 
   
   
       19 . The method recited in  claim 9  wherein contacting the metal surfaces comprises introducing the lubricant into the flow of compressed air in a pneumatic tool. 
   
   
       20 . The method recited in  claim 9  wherein contacting the metal surfaces comprises applying the lubricant directly to the metal surfaces in need of lubrication.