Modified polyisobutylene succinimide dispersants having improved seal, sludge, and deposit performance

Abstract

A composition suitable for reducing sludge and degradation of elastomer seals in engines comprises an oil of lubrication viscosity and a minor amount of a sludge preventing/seal protecting nitrogen containing dispersant, which is a reaction product of a hydrocarbyl-substituted succinic acylating agent having a limited amount of low molecular weight substituent; and a polyamine or condensed polyamine containing less than 20 mole percent of polyamine components of 6 or fewer nitrogen atoms.

What is claimed is:  
     
         1 . A composition suitable for reducing engine sludge and degradation of elastomer seals comprising 
 a major amount of an oil of lubricating viscosity and    a minor amount of a nitrogen-containing dispersant wherein the nitrogen containing dispersant is a reaction product of 
 (I) a hydrocarbyl-substituted succinic acylating agent, wherein 15 to about 20 mole percent of the individual molecules thereof have a hydrocalbyl substituent with a molecular weight of less than 500; wherein the hydrocarbyl substituent is a polymeric species consisting essentially of olefin monomer units of at least 3 carbon atoms; and  
 (II) at least one polyamine, wherein the polyamine is 
 (a) a polyalkylene amine containing at least one H—N< group; or  
 (b) a condensate of (i) a polyalkylene amine containing at least one H—N< group with (ii) at least one alcohol containing at least one ether group, amine group, nitro group, or additional alcohol group; 
 wherein in said polyamine (a) or condensed polyamine (b) no more than about 20 mole percent of the molecules contain 6 or fewer nitrogen atoms.  
 
 
   
     
     
         2 . The composition of  claim 1  wherein the substituent groups in (I) are derived from a polyalkene characterized by a Mn value of about 1000 to about 10,000.  
     
     
         3 . The composition of  claim 2  wherein Mn is at least about 2000.  
     
     
         4 . The composition of  claim 1  wherein the substituent groups in (I) are derived from one or more homopolymers or copolymers of olefins of 3 to about 16 carbon atoms.  
     
     
         5 . The composition of  claim 4  wherein the olefins are predominantly terminal olefins.  
     
     
         6 . The composition of  claim 4  wherein the substituent groups are derived from one or more homopolymers or copolymers of olefins of 3 to about 6 carbon atoms.  
     
     
         7 . The composition of  claim 6  wherein the substituent groups are derived from polybutene, polypropylene, or mixtures thereof.  
     
     
         8 . The composition of  claim 6  wherein the substituent groups are derived from polybutene in which at least about 50 mole percent of the monomer units are isobutylene units  
     
     
         9 . The composition of  claim 1  wherein the acylating agent is characterized by the presence within its structure of an average of at least about 1.1 succinic groups for each equivalent weight of substituent groups.  
     
     
         10 . The composition of  claim 1  wherein the acylating agent is characterized by the presence within its structure of an average of at least about 1.3 succinic groups for each equivalent weight of substituent groups.  
     
     
         11 . The composition of  claim 1  wherein the alkylene moiety of the polyalkylene amine of (IIa) or (IIb) is ethylene.  
     
     
         12 . The composition of  claim 1  wherein for (IIa), less than about 10 mole percent of the polyamine molecules contain six or fewer nitrogen atoms.  
     
     
         13 . The composition of  claim 1  wherein for (IIa) less than about 5 mole percent of polyamine molecules contain six or fewer nitrogen atoms.  
     
     
         14 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is of the formula 
       R 1   m X—R 2 —(R 3 OH) n   
       wherein: 
 X is O or N;  
 m is 1 when X is O and 2 when X is N;  
 each R 1  is independently hydrogen, a hydrocarbyl group, a hydroxy-hydrocarbyl group, or, if X is N, each R 1  can be O so as to form a NO 2  group;  
 R 2  is a hydrocarbylene group or an ether-containing group, having n+1 sites of linkage  
 R 3  is an alkylene group of 1 to about 4 carbon atoms; and  
 n is 1, 2, or 3.  
 
     
     
         15 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is a di- or tri-ethanolamine.  
     
     
         16 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is trimethylolpropane.  
     
     
         17 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is pentaerythritol.  
     
     
         18 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is tris(hydroxymethyl)amino methane.  
     
     
         19 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is tris(hydroxyethyl)amino methane.  
     
     
         20 . The composition of  claim 1  wherein the alcohol of II(b)(ii) is a polyoxyalkylene alcohol.  
     
     
         21 . The composition of  claim 1  wherein within (IIb) the condensed polyamine is prepared by reacting about 1 to about 3 equivalent of the polyamine with 1 equivalent of the alcohol in the presence of an acid catalyst.  
     
     
         22 . The composition of  claim 1  wherein the nitrogen-containing dispersant is prepared by reacting (I) the hydrocarbyl-substituted succinic acylating agent with (IIa) the polyethylene polyamines.  
     
     
         23 . The composition of  claim 1  wherein the nitrogen-containing dispersant is prepared by reacting (I) the hydrocarbyl-substituted succinic acylating agent with (IIb) the condensed polyamine.  
     
     
         24 . A method for reducing the formation of sludge and the degradation of seals in an engine, comprising lubricating said engine with the composition of  claim 1 .  
     
     
         25 . A composition suitable for reducing engine sludge and degradation of elastomer seals comprising 
 a major amount of an oil of lubricating viscosity and    a minor amount of a nitrogen-containing dispersant wherein the nitrogen containing dispersant is a reaction product of 
 (I) a hydrocarbyl-substituted succinic acylating agent wherein the hydrocarbyl substituent is prepared from a polymeric species consisting essentially of olefin monomer units of at least 3 carbon atoms and wherein 15 to about 20 mole percent of the individual molecules of said polymeric species have a molecular weight of less than 500; and  
 (II) at least one polyamine, wherein the polyamine is 
 (a) a polyalkylene amine containing at least one H—N< group; or  
 (b) a condensate of (i) a polyalkylene amine containing at least one H—N< group with (ii) at least one alcohol containing at least one ether group, amine group, nitro group, or additional alcohol group; 
 wherein in said polyamine (a) or condensed polyamine (b) no more than about 20 mole percent of the molecules contain 6 or fewer nitrogen atoms.