Succinimide compound, process for producing the same, lubricating oil additive, and lubricating oil composition for internal combustion engine

Abstract

Provided are novel succinimide compounds obtained by reacting a polyamine having a carbon/nitrogen weight ratio of from 0.85 to 1.25 with a succinic acid compound in a molar ratio to the polyamine of up to 1.40; a process for producing them; a lubricating oil additive containing the compound; and a lubricating oil composition for internal combustion engines which comprises a lube base oil, (a) at least one compound selected from the group consisting of overbased sulfonates, phenates and salicylates with alkaline earth metals, and (b) the succinimide compound, and which has a total base number of from 30 to 150 mg-KOH/g. The composition is for use in internal combustion engines that may discharge a large amount of sulfur oxides (SOx), having the advantage of good corrosion resistance against SOx to be discharged in large quantities.

1 . Succinimide compounds obtained by reacting a polyamine having a carbon/nitrogen weight ratio of from 0.85 to 1.25 with a succinic acid compound of the following general formula (I) or (II) in a molar ratio to the polyamine of up to 1.40: 
       
         
           
           
               
               
           
         
       
       wherein R represents an alkenyl or alkyl group derived from an olefinic polymer having a carbon number of from 2 to 15 and having a number-average molecular weight of from 200 to 4,000.  
     
     
         2 . A process for producing succinimide compounds by reacting a polyamine having a carbon/nitrogen weight ratio of from 0.85 to 1.25 with a succinic acid compound of the following general formula (I) or (II) in a molar ratio to the polyamine of up to 1.40: 
       
         
           
           
               
               
           
         
       
       wherein R represents an alkenyl or alkyl group derived from an olefinic polymer having a carbon number of from 2 to 15 and having a number-average molecular weight of from 200 to 4,000.  
     
     
         3 . A lubricating oil additive containing the succinimide compound of  claim 1 .  
     
     
         4 . A lubricating oil composition for internal combustion engines, which comprises a lube base oil, and (a) at least one compound selected from the group consisting of overbased sulfonates, phenates and salicylates of alkaline earth metals, and (b) the succinimide compound of  claim 1 , and which has a total base number of from 30 to 150 mg-KOH/g.  
     
     
         5 . The lubricating oil composition for internal combustion engines as claimed in  claim 4 , wherein the component (a) accounts for from 5 to 40% by weight and the component (b) for from 0.1 to 3% by weight based on the total weight of the composition.