Transformer oil composition, comprising at least one acid interceptor

Abstract

The invention relates to a transformer oil composition comprising at least one acid interceptor. The invention further relates to the use of acid interceptor in transformer oils for improving stability.

What is claimed is: 
     
         1 . A composition comprising at least one transformer oil and at least one acid scavenger. 
     
     
         2 . The composition as claimed in  claim 1 , characterized in that the at least one acid scavenger is selected from the group consisting of carbodiimides; epoxidized triglycerides; trialkylamines, dialkylamines; pyridines and pyridine derivatives; diazabicyclooctane; and polyvinylpyridine. 
     
     
         3 . The composition as claimed in  claim 2 , characterized in that the acid scavenger is at least one carbodiimide. 
     
     
         4 . The composition as claimed in  claim 3 , characterized in that the at least one carbodiimide is a monomeric carbodiimide of the general formula (I) 
       
         
           
           
               
               
           
         
         in which the R 1  to R 4  radicals are each independently a straight-chain or branched C 2 - to C 20 -alkyl radical, a C 2 - to C 20 -cycloalkyl radical, a C 6 - to C 15 -aryl radical or a C 6 - to C 15 -aralkyl radical. 
       
     
     
         5 . The composition as claimed in  claim 3 , characterized in that the at least one carbodiimide is a carbodiimide of the general formula (II)
   R′—(—N═C═N—R—) n —R″  (II)
   in which
 R is an aromatic, aliphatic, cycloaliphatic or araliphatic radical which, in the case of an aromatic or araliphatic radical in one ortho position, preferably in both ortho positions, to the aromatic carbon atom which bears the carbodiimide group, may bear aliphatic and/or cycloaliphatic substituents having at least 2 carbon atoms, preferably branched or cyclic aliphatic radicals having at least 3 carbon atoms, especially isopropyl groups, 
   R′ is aryl, aralkyl or R—NCO, R—NHCONHR 1 , R—NHCONR 1 R 2  and R—NHCOOR 3 ,   R″ is —N═C═N-aryl, —N═C═N-alkyl, —N═C═N-cycloaliphatic, —N═C═N-aralkyl, —NCO, —NHCONHR 1 , —NHCONR 1 R 2  or NHCOOR 3 ,   where, in R′ and in R″ independently, R 1  and R 2  are the same or different and are each an alkyl, cycloalkyl or aralkyl radical and R 3  has one of the definitions of R 1 , or is a polyester or polyamide radical, and
 n is an integer from 1 to 5000, preferably from 1 to 500. 
   
     
     
         6 . The composition as claimed in any of  claims 3  to  5 , characterized in that the carbodiimides are used as mixtures. 
     
     
         7 . The composition as claimed in any of  claims 3  to  6 , characterized in that the amount of the at least one carbodiimide in the composition is 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, especially 0.1 to 1.5% by weight. 
     
     
         8 . The composition as claimed in any of  claims 1  to  7 , characterized in that the transformer oil is selected from oils based on mineral oil, based on esters or based on triglycerides. 
     
     
         9 . The composition as claimed in any of  claims 1  to  8 , characterized in that the transformer oil is a trimethylolpropane ester (TMP) of the general formula (III) 
       
         
           
           
               
               
           
         
         where R 1 , R 2  and R 3  are the same or different and are each a linear or branched alkyl group having 5 to 11 carbon atoms. 
       
     
     
         10 . The composition as claimed in any of  claims 1  to  9 , characterized in that the transformer oil is a pentaerythrityl ester. 
     
     
         11 . The use of at least one acid scavenger as defined in  claim 2  for protection of transformers from corrosion or as a stabilizer in transformer oils. 
     
     
         12 . The use of at least one carbodiimide corresponding to the definition according to any of  claims 3  to  5  as an acid scavenger. 
     
     
         13 . A process for producing a composition as claimed in any of  claims 1  to  10 , characterized in that a transformer oil is mixed with at least one acid scavenger. 
     
     
         14 . A transformer comprising a composition as claimed in any of  claims 1  to  10 .