Quaternary ammonium salt composition and lubricating oil containing same

A quaternary ammonium salt composition represented by the formula: ##STR1## in which R is a hydrocarbyl radical having from 25 to 200 carbon atoms, x is a number from 2 to 4, y has a value from 0 to 4, R' is a hydrocarbyl radical having from 1 to 10 carbon atoms, and z is a number from 0 to 2, is provided, as well as a method of preparation and a lubricating oil composition containing same.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Internal combustion engines operate under a wide range of temperatures 
including low-temperature stop-and-go service as well as high-temperature 
conditions produced by continuous high speed driving. Stop-and-go driving, 
particularly during cold, damp weather conditions, leads to the formation 
of sludge in the crankcase and in the oil passages of a gasoline engine. 
This sludge seriously limits the ability of the crankcase oil to lubricate 
the bearings and sliding wear surfaces in the engine or to act as a 
coolant. In addition, the sludge serves to contribute to rust formation 
within the engine because it tends to retain water in areas susceptible to 
corrosion. The noted problems are compounded by lubrication service 
maintenance recommendations calling for extended oil drain intervals. 
It is known to employ nitrogen-containing dispersants and/or detergents in 
the formulation of crankcase lubricating oil compositions. Many of the 
known dispersant/detergent compounds are based on the reaction of an 
alkenylsuccinic acid or anhydride with an amine or polyamine to produce an 
alkenylsuccinimide or an alkenylsuccinamic acid as determined by selected 
conditions of reaction. 
It is also known to chlorinate alkenylsuccinic acid or anhydride prior to 
the reaction with an amine or polyamine in order to produce a reaction 
product in which a portion of the amine or polyamine is attached directly 
to the alkenyl radical of the alkenylsuccinic acid or anhydride. The 
thrust of many of these processes is to produce a dispersant reaction 
product typically containing from about 0.5 to 5% nitrogen. These 
dispersant additives exhibited a high degree of oil solubility and have 
been found to be effective for dispersing the sludge that is formed under 
severe low temperature stop-and-go engine operating conditions. However, 
it has become increasingly difficult to formulate lubricants with these 
additives which meet the present requirements with respect to the 
prevention or inhibition of the formation of varnish. 
2. Description of the Prior Art 
A copending application, Ser. No. 224,728, filed on Jan. 13, 1981, 
discloses a quaternary ammonium succinimide salt composition formed from 
an N-(haloalkyl)hydrocarbylsuccinimide and a heteroaromatic amine and 
lubricants containing same. 
A copending application, Ser. No. 246,512, filed on Mar. 21, 1981, 
discloses a quaternary ammonium succinimide salt composition prepared from 
an aminopyridine derived hydrocarbyl succinimide and an alkyl halide and 
lubricants containing same. 
SUMMARY OF THE INVENTION 
The quaternary ammonium salt composition of this invention is represented 
by the formula: 
##STR2## 
in which R is a hydrocarbyl radical having from 25 to 200 carbon atoms, X 
is a number from 2 to 4, y has a value from 0 to 4, R is a hydrocarbyl 
radical having from 1 to 10 carbon atoms and z is a number from 0 to 2. 
The novel quaternary ammonium salt composition of the invention is prepared 
by reacting a hydrocarbon-substituted succinic anhydride with a polyamine 
to produce an intermediate hydrocarbon derivative of a succinic compound. 
This intermediate is then reacted with epichlorohydrin and a tertiary 
heteroaromatic amine to form the prescribed quaternary ammonium salt 
dispersant of the invention. 
The lubricating oil composition or lubricant concentrate of the invention 
comprises a substrate of lubricant viscosity and an effective dispersant 
amount of the prescribed quaternary ammonium salt of the invention. 
DESCRIPTION OF THE PREFERRED INVENTION 
The novel quaternary ammonium salt composition of the invention is 
represented by the formula: 
##STR3## 
in which R is a hydrocarbyl radical having from 25 to 200 carbon atoms, x 
is a number from 2 to 4, y has a value from 0 to 4, R' is a hydrocarbyl 
radical having from 1 to 10 carbon atoms and z is a number from 0 to 2. 
A preferred additive of the invention is a quaternary ammonium succinimide 
salt in which R is an alkenyl radical, such as a polybutenyl, 
polyisobutenyl, and polypropenyl radical, having from 50 to 125 carbon 
atoms or still more preferred from 70 to 100 carbon atoms. 
The preparation of a quaternary ammonium succinimide salt composition of 
the invention begins with a hydrocarbyl-substituted succinimide 
intermediate. This starting succinimide reactant is represented by the 
formula: 
##STR4## 
in which R, x and y have values noted above. The method for preparing 
hydrocarbyl succinimides is well known in the art and does not constitute 
a part of this invention. 
The hydrocarbyl succinimide is reacted with epichlorohydrin and a tertiary 
heteroaromatic amine in order to form the prescribed quaternary ammonium 
salt. The effective tertiary heteroaromatic amine is represented by the 
formula: 
##STR5## 
in which R' is a hydrocarbyl radical having from 1 to 10 carbon atoms and 
z is a number from 0 to 2. 
The preferred heteroaromatic amine is one in which R' is a lower aliphatic 
hydrocarbon radical having from 1 to 4 carbon atoms and z is 1. 
Examples of effective tertiary heteroaromatic amines include pyridine, 
3-methylpyridine, 3,4-dimethylpyridine, 4-methylpyridine, 3-ethylpyridine, 
and 4-ethylpyridine.

The following examples illustrate the method for preparing the quaternary 
ammonium salt compositon of the invention. 
EXAMPLE I 
Fourteen hundred grams of polyisobutenyl (1300 MW) succinic acid anhydride 
(saponification number of 51) was mixed with 180 grams of ethylenediamine 
(approximately a 1:5 mole ratio) in a reaction vessel under an inert 
nitrogen blanket. The mixture was heated at 90.degree. C. for 3 hours and 
then stripped under a vacuum until no further distillate evolved from the 
intermediate reaction product. The yield of the intermediate (Intermediate 
A) was 1424 grams and it analyzed at 1.40% nitrogen. The principal 
intermediate product is a succinimide represented by the formula: 
##STR6## 
where R is a polyisobutenyl radical of about 1300 molecular weight. 
The intermediate reaction product was mixed with 4-picoline in a mole ratio 
of one mole of succinimide to five moles 4-picoline. This mixture was 
heated to 110.degree. C. and one mole equivalent of epichlorohydrin based 
on the succinimide was added. The resulting mixture was heated at 
140.degree. C. for 4 hours and then stripped under reduced pressure at a 
temperature of 100.degree. to 110.degree. C. to remove unreacted 
4-picoline. On analysis, the resulting product (Product A) was found to 
contain 2.1 weight percent nitrogen and 1.49 weight percent chlorine. A 
key component of the reaction product is postulated to have the formula: 
##STR7## 
where R is polyisobutenyl of about 1300 mol. wt. 
EXAMPLE II 
Four hundred grams of polyisobutenyl (1300 MW) succinic anhydride 
(saponification number of 53), 11.3 grams of urea, 250 ml of xylene and 5 
ml of water were combined, and the resulting mixture was stirred under 
reflux at 145.degree. C. for 4 hours as water was removed by azeotropic 
distillation. The mixture was diluted with 400 grams of oil, stripped of 
volatiles under reduced pressure and then filtered. On analysis, this 
intermediate product (Intermediate B) was found to contain 0.36 weight 
percent nitrogen. The principal intermediate product is a succinimide 
postulated to be represented by the formula: 
##STR8## 
The intermediate reaction product was mixed with 4-picoline in a mole ratio 
of one mole of succinimide to four moles of 4-picoline. This mixture was 
heated to 110.degree. C. and one and two tenths mole equivalents of 
epichlorohydrin based on the succinimide was added. The resulting mixture 
was heated at 110.degree. C. for 8 hours and then stripped under reduced 
pressure at a temperature of 100.degree. to 110.degree. C. to remove 
unreacted 4-picoline. The resulting product was found to contain 0.49 
weight percent nitrogen and 0.90 weight percent chlorine. A key component 
of the reaction product is postulated to have the formula: 
##STR9## 
The lubricant composition of the invention comprises a major amount of a 
base oil, i.e., a mineral hydrocarbon oil or a synthetic oil of 
lubricating viscosity and effective detergent-dispersant amount of the 
prescribed quaternary ammonium salt. Advantageously, in the finished 
lubricating salt oil composition, the prescribed quaternary ammonium salt 
content ranges between about 0.1 and 10 percent by weight, preferably 
between about 0.5 and 5 weight percent. In the lubricating oil 
concentrates from which the finished lubricating compositions are derived 
via the addition of added lubricating oil, quaternary ammonium salt 
contents between about 10 and 60 weight percent are found. Thus, 
concentrations of the additive in lubricating oils and lubricating oil 
concentrates range from about 0.1 to 60 weight percent. The base oil in 
the finished lubricating composition advantageously constitutes at least 
about 85 weight percent and preferably between about 90 and 98 weight 
percent of the composition. It should be noted that the lubricating oil 
concentrates containing the prescribed quaternary ammonium salt will 
exhibit detergent/dispersancy. 
Examples of the hydrocarbon base oil contemplated herein are the naphthenic 
base, paraffinic base and mixed base mineral oils, lubricating oils 
derived from coal products and synthetic oils, e.g., alkylene polymers 
such as polypropylene and polyisobutylene of a molecular weight of between 
about 250 and 2500. Advantageously, a lubricating base oil having a 
lubricating oil viscosity at 100.degree. F. of between about 50 and 1000, 
preferably between about 100 and 600, are normally employed for the 
lubricant compositions and concentrates thereof (SUS basis). 
In the contemplated finished lubricating oil compositions other additives 
may be included in addition to the dispersant of the invention. The 
additives may be any of the suitable standard pour depressants, viscosity 
index improvers, oxidation, corrosion, and wear inhibitors, antifoamants, 
supplementary detergent-dispersants, etc. The choice of the particular 
additional additives to be included in the finished oils and the 
particular amounts thereof will depend on the use and conditions desired 
for the finished oil product. 
The following test was employed to determine the dispersant effectiveness 
of the lubricant composition of the invention. 
BENCH VC TEST 
In the Bench VC Test, a mixture containing the test oil and a diluent are 
heated at an elevated temperature. After heating, the turbidity of the 
resultant mixture is measured. A low % turbidity (0-10) is indicative of 
good dispersancy while high results (20-100) are indicative of oils of 
increasingly poor dispersancy. 
EXAMPLE III 
A fully formulated SAE Grade 10W-40 lubricating oil composition containing 
the quaternary ammonium salt of the invention was tested for its 
dispersant effectiveness in the Bench VC Test in comparison to a fully 
formulated base oil without the amine salt dispersant and to the base oil 
containing the intermediate reaction product. 
The base blend employed contained the following conventional additives: 
0.15 weight % zinc as zinc dialkyldithiophosphate 
0.23 weight % calcium as overbased calcium sulfonate 
0.25 weight % alkylated diphenylamine antioxidant 
11.5 weight % ethylene-propylene copolymer VI improver 
0.15 weight % ethoxylated alkylphenol 
0.10 weight % methacrylate pour depressant 
150 ppm silicone antifoamant 
mineral oil--balance (viscosity SUS at 100.degree. F. of 120) 
The quaternary ammonium salt dispersant of the invention and its precursors 
were added to the base blend and then tested in the Bench VC Test. The 
results are set forth in the table below: 
TABLE I 
______________________________________ 
BENCH VC TEST 
Wt. %-Diluent 
Run Lubricant Composition 
Oil Free Basis 
Turbidity 
______________________________________ 
1 Base Blend (no dispersant) 
-- 97.5 
2 Base Blend + Intermediate A 
3.0 15.0 
3 Base Blend + Intermediate B 
1.5 64.5 
4 Base Blend + Example 1 
3.0 6.0 
(Product A) 
5 Base Blend + Example 2 
1.5 7.0 
(Product B) 
______________________________________ 
The foregoing tests demonstrate that the prescribed quaternary ammonium 
salts of the invention are excellent dispersants for lubricating oil 
compositions exhibiting an effectiveness that is superior to that of the 
succinimide precursors from which they were prepared.