Use of block-copolymeric polyalkylene oxides as friction reducers in synthetic lubricants

Abstract

The invention relates to the use of block copolymers containing at least a block of aromatic oxyalkylene groups and a block of nonaromatic oxyalkylene groups as friction-reducing additive and also compositions and lubricant formulations containing the block copolymers of the invention.

1 . A method of using a block copolymer containing at least a block of aromatic oxyalkylene groups and a block of nonaromatic oxyalkylene groups as a friction-reducing additive. 
     
     
         2 . The method according to  claim 1 , wherein the block copolymer contains at least one block of aromatic oxyalkylene groups having more than one aromatic oxyalkylene group and at least one block of nonaromatic oxyalkylene groups having more than 2 nonaromatic oxyalkylene groups. 
     
     
         3 . The method according to  claim 1 , wherein the block copolymer is a compound of formula (1)
   R 1 [O(AO) g (NAO) h R 2 ] n   Formula (1)
   where   n is from 1 to 8,   g is greater than or equal to from 1 to 9,   h is greater than or equal to from 3 to 50,   R 1  is a straight-chain or branched or cycloaliphatic hydrocarbon radical having from 1 to 15 carbon atoms,   R 2  is hydrogen or an alkyl radical having from 1 to 8 carbon atoms,   AO independently of one another, aromatic oxyalkylene groups,   NAO independently of one another, nonaromatic oxyalkylene groups.   
     
     
         4 . The method according to  claim 1 , wherein the block copolymer is a compound of formula (2)
   R 1 [O(SO) a (EO) b (PO) c (BO) d R 2 ] a1   Formula (2)
   where   a1 is from 1 to 8,   R 1  is a straight-chain or branched or cycloaliphatic hydrocarbon radical having from 1 to 15 carbon atoms,   R 2  is hydrogen or an alkyl radical having from 1 to 8 carbon atoms,   SO is oxystyrene,   EO is oxyethylene,   PO is oxypropylene,   BO is oxybutylene and   a is from 1 to 9,   b is from 1 to 20,   c is from 0 to 20,   d is from 0 to 10.   
     
     
         5 . A composition of at least one block copolymer containing at least a block of aromatic oxyalkylene groups and a block of nonaromatic oxyalkylene groups together with at least one antioxidant. 
     
     
         6 . The composition according to  claim 5 , wherein the composition contains at least 500 ppm of metal ions, based on the mass of the block copolymers used. 
     
     
         7 . A method of using the block copolymers according to  claim 1  for producing lubricant formulations. 
     
     
         8 . A lubricant formulation containing block copolymers which contain a block of aromatic oxyalkylene groups and a block of nonaromatic oxyalkylene groups in a synthetic base oil or synthetic lubricant. 
     
     
         9 . The lubricant formulation according to  claim 8 , further comprising additives selected from the group consisting of synthetic oils, extreme pressure/antiwear additives (ep/aw additives), corrosion inhibitors, biocides, defoamers, dispersants, metal deactivators or viscosity index improvers. 
     
     
         10 . The lubricant formulations according to  claim 8 , wherein the block copolymers are used in a concentration of 0.1-9% by weight, based on the total lubricant formulation. 
     
     
         11 . The lubricant formulations according to  claim 8 , wherein the synthetic oils are polyalkylene glycols.