Lubricating Oil Composition and Method for Operating Automatic Transmission

Abstract

A lubricating oil composition containing a bis-type alkenyl-substituted succinimide which is prepared by reaction of succinic anhydride substituted with 2-alkenyl group having a branched structure in β-position with alkylenepolyamine or a compound derived from the bis-type alkenyl-substituted succinimide by post-treatment in combination with a mixture of an overbased sulfonate having a C 20 -C 24 alkyl group and an overbased salicylate having a C 14 -C 18 alkyl group shows a high friction coefficient within a wide sliding velocity range and keeps its high anti-shudder performance for a long period of time.

1 . A lubricating oil composition comprising a base oil having a lubricating viscosity and the following additives:
 a friction modifier in an amount of 0.1 to 10 wt. %, a nitrogen-containing ashless dispersant in an amount of 0.05 to 10 wt. %,   a phosphorus compound in an amount of 0.1 to 10 wt. %, and   a metal-containing detergent in an amount of 0.005 to 4 wt. %,   in which the amounts of the additives are based on an amount of the lubricating oil composition,   the friction modifier is selected from the group consisting of:   a friction modifier (A) comprising an alkenyl-substituted succinimide of the following formula (1) or a post-treated derivative thereof:   
       
         
           
           
               
               
           
         
       
       in which each of R 1  and R 1 ′ independently is an alkenyl group having a branched structure in β-position which is represented by the following formula (1), R 2  is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 13 carbon atoms, or a 5-8 membered heterocyclic group, x is an integer of 1 to 6, and y is an integer of 0 to 20: 
       
         
           
           
               
               
           
         
       
       in which each of R 3  and R 4  is an aliphatic hydrocarbyl group and a total carbon atom number of R 3  an R 4  is in the range of 3 to 45, under the condition that a carbon atom number of R 3  is larger than a carbon atom number of R 4  by 3 or a carbon atom number of R 3  is smaller than a carbon atom number of R 4  by 1; and,
 a friction modifier (B) which comprises an alkenyl-substituted succinimide of the following formula (II) or a post-treated derivative thereof: 
 
       
         
           
           
               
               
           
         
       
       in which each of R 1  and R 1 ′ independently is an alkenyl group having a branched structure in β-position which is derived from a dimer of a single linear α-olefin having 3 to 24 carbon atoms, and Q is a residue of an alkylene-polyamine having a 1 to 20 carbon atoms and containing an amino group at least at each terminal thereof, and
 said metal-containing detergent is a mixture of an overbased sulfonate having an alkyl group containing 20-24 carbon atoms and an overbased salicylate having an alkyl group containing 14-18 carbon atoms in a weight ratio of 1:4 to 4:1. 
 
     
     
         2 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (A) in which each of R 3  and R 4  in the formula (1) independently is a linear alkyl group and the total carbon atom number contained in R 3  and R 4  is in the range of 13 to 21. 
     
     
         3 . The lubricating oil composition of  claim 1 , in which x is 2 and y is an integer of 1 to 3. 
     
     
         4 . The lubricating oil composition of  claim 1 , in which x is 2 and y is 1. 
     
     
         5 . The lubricating oil composition of  claim 1 , in which the post-treated derivative is an alkenyl-substituted succinimide of formula (1) which is post-treated with boric acid, phosphoric acid, a carboxylic acid, or ethylene carbonate. 
     
     
         6 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the dimer is prepared by dimerization of a linear α-olefin having 8 to 12 carbon atoms. 
     
     
         7 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the dimer is 2-hexyl-1-decene, 2-octyl-1-dodecene or 2-decyl-1-tetradecene. 
     
     
         8 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the dimer is 2-octyl-1-dodecene. 
     
     
         9 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the alkylene-polyamine is ethylenediamine, diethylenetriamine or triethylenetetramine. 
     
     
         10 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the alkylene-polyamine is diethylenetriamine. 
     
     
         11 . The lubricating oil composition of  claim 1 , in which the friction modifier is the friction modifier (B) wherein the post-treated derivative is the alkenyl-substituted succinimide of formula (II) which is post-treated with boric acid, phosphoric acid, a carboxylic acid or ethylene carbonate. 
     
     
         12 . The lubricating oil composition of  claim 1 , in which the overbased sulfonate has a TBN in the range of 120 to 400 mg KOH/g and the overbased salicylate has a TBN in the range of 60 to 330 mg KOH/g. 
     
     
         13 . The lubricating oil composition of  claim 1 , which is a lubricating oil for automatic transmissions. 
     
     
         14 . The lubricating oil composition of  claim 13 , in which the automatic transmissions are selected from the group consisting of automatic transmissions, continuously variable transmissions and dual clutch transmissions. 
     
     
         15 . A method for operating an automatic transmission in the presence of the lubricating oil composition of  claim 1 . 
     
     
         16 . The method of  claim 15 , in which the automatic transmission is selected from the group consisting of automatic transmissions, continuously variable transmissions and dual clutch transmissions.