A dispersant/antioxidant bound VII polymethacrylate lubricant additive composition prepared by: PA0 (a) combining a polyunsaturated monomer with (C.sub.1 -C.sub.20) alkyl monomers and, optionally, a dispersant monomer in an oil solvent to provide an intermediate reaction mixture; PA0 (b) stirring and purging the reaction mixture; PA0 (c) heating the purged mixture and adding a radical polymerization catalyst to the purged mixture; PA0 (d) heating the mixture to a sufficiently high temperature to remove any excess of the polymerization catalyst therefrom; PA0 (e) (optionally) recovering the intermediate product polymethacrylate; PA0 (f) combining the intermediate product with an aromatic nitroso compound to provide an intermediate reaction mixture; PA0 (g) stirring and purging the intermediate reaction mixture; and PA0 (h) recovering from the purged mixture the product polymethacrylate.

BACKGROUND OF THE INVENTION 
This invention relates to Viscosity Index Improvers (VII), and more 
particularly to an antioxidant bound Viscosity Index Improving 
polymethacrylate lubricant additive. 
As is well known to those skilled in the art, lubricating oils for internal 
combustion engines typically contain a multitude of additives which 
function as detergents, dispersants, viscosity index improvers, pour 
depressants, etc., to improve the properties of the oil. It is found that 
it is particularly necessary to improve the resistance of a lubricating 
oil to oxidation. 
In developing suitable additives for imparting various properties to 
lubricating oils, polymethacrylate polymers have been found to be useful 
for a variety of applications in lubricants. Some of their chief uses are 
as Viscosity Index (VI) improvers and pour point depressants (PPD's) for 
lubricants. The preparation of functionalized PMA's has increased in 
recent years. Many functionalized PMA's contain some amine functionality 
for the purpose of imparting dispersancy to the polymer. Other 
functionalized PMA's are also known, but to a lesser extent. There are, 
however, only a few examples of antioxidants being incorporated into the 
polymers. In developing PMA's which impart multifunctional properties to 
VII's and lubricants there has not been proved an adequate process for 
synthesizing a multifunctional PMA, incorporating antioxidants. 
Thus, it is an object of the present invention to provide a method, i.e. a 
synthesis, for producing antioxidant polymethacrylates (PMA's). 
DISCLOSURE STATEMENT 
U.S. Pat. No. 4,036,766 discloses a complex reaction product of (I) an 
interpolymer of dialkylamino methacrylate, C.sub.1 -C.sub.6 alkyl 
methacrylate, C.sub.10 -C.sub.14 alkyl methacrylate and C.sub.16 -C.sub.20 
alkyl methacrylate monomers and (2) a liquid poly (alkene-1) of molecular 
weight between about 200 and 10,000 prepared by polymerizing the monomers 
comprising said interpolymer in the presence of said liquid poly 
(alkene-1). A mineral oil composition of improved viscosity, pour 
depressing and detergent-dispersant properties and concentrates thereof 
comprising between about 10 and 95 wt.% of a mineral oil of a lubricating 
viscosity and between about 0.1 and 90 wt. % of said complex product. 
U.S. Pat. No. 4,606,834 discloses lubricating oil compositions which 
contain a VI improving (VII) pour point depressant. The VII consists 
essentially of a terpolymer where the monomers are selected from various 
(C.sub.10 -C.sub.20) acrylates. 
U.S. Pat. No. 4,098,709 discloses polymers containing post-reacted hindered 
phenol antioxidant functionality as viscosity index (VI) improvers for 
high temperature service, particularly for lubricating oils used in diesel 
engines. 
Co-assigned U.S. Application No. 172,664 discloses a reaction product of an 
ethylene copolymer or terpolymer of a (C.sub.3 -C.sub.10) alphamonolefin 
and optionally a non-conjugated diene or triene on which has been grafted 
an ethylenically unsaturated carboxylic function which is then further 
derivatized with an amino-aromatic polyamine compound. 
Co-assigned U.S. Application No. 07/419,407 discloses a 
dispersant/antioxidant bound, Viscosity Index-improving polymethacrylate 
composition having a molecular weight ranging from about 20,000 to about 
2,500,000. The composition was comprised of a base oil and effective 
amounts of dispersant and antioxidant monomers. 
Co-assigned U.S. Application No. 07/419,565 discloses an antioxidant bound 
Viscosity Index-improving polymethacrylate composition having molecular 
weight ranging from about 20,000 to about 2,500,000. The composition was 
comprised of a base oil and effective amounts of alkyl and antioxidant 
monomers. 
SUMMARY OF THE INVENTION 
The invention provides antioxidant and dispersant/antioxidant bound, 
Viscosity Index-improving polymethacrylate compositions having a molecular 
weights ranging from about 20,000 to about 2,500,000. The composition 
comprises a base oil and effective amounts of alkyl methacrylate monomers, 
a polyunsaturated monomer, an aromatic nitroso compound and, optionally, a 
dispersant monomer. The composition being prepared by: 
(a) combining a polyunsaturated monomer with (C.sub.1 -C.sub.20) alkyl 
monomers and (optionally) a dispersant monomer, in an oil solvent to 
provide an intermediate reaction mixture; 
(b) stirring and purging the reaction mixture by nitrogen ebullition at 
about 200 ml/min for about 25-35 minutes; 
(c) reducing the nitrogen ebullition to about 20 ml/min; 
(d) heating the purged mixture to about 70.degree. C.-85.degree. C. and 
adding a radical polymerization catalyst to the purged mixture; 
(e) increasing the temperature of the heated mixture to about 95.degree. 
-105.degree. C. and maintaining the mixture at such temperature for a 
sufficient period of time to remove any excess of the polymerization 
catalyst; and 
(f) (optional) recovering the intermediate product polymethacrylate; 
(g) combining the intermediate polymethacrylate with an aromatic nitroso 
compound to provide an intermediate reaction mixture; 
(h) stirring the intermediate reaction mixture 5 while purging the mixture 
with nitrogen at a rate of 20 ml/min for about 20-25 min; 
(i) heating the reaction mixture to 120.degree. C. and maintaining the 
mixture temperature for 30 min; 
(j) increasing the temperature of the reaction mixture to -60.degree. C. 
while collecting water over I.0 hours; and 
(k) recovering the product polymethacrylate. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention resides in antioxidant and dispersant/antioxidant 
bound, Viscosity Index Improving (VII) polymethacrylate lubricant 
additives comprising alkyl methacrylate monomers, a polyunsaturated 
monomer, an aromatic nitroso compound, and optionally, a dispersant 
monomer. 
The polyunsaturated monomers that may be used to make the present lubricant 
additive may be selected from the group consisting of an acrylate, 
methacrylate, an acrylamide or a methacrylamide derived from acrylic acid 
or methacrylic acid or their derivatives, and an unsaturated alcohol, 
phenol or amine. 
The polyunsaturated monomer that may be used is represented by the formula: 
##STR1## 
where R.sup.1 is a lower chain alkyl, preferably methyl or ethyl and 
R.sup.2 is an unsaturated moiety derived from an unsaturated alcohol or 
unsaturated amine such as oleyl alcohol, linoleic or linolinic alcohol, 
oleylamine, allyl alcohol or allylamine. R.sup.2 may also be derived from 
unsaturated phenols such as p-hydroxy-.alpha.-alkylstyrene or 
p-hydroxy-.beta.-alkylstyrene, and unsaturated amines such as 
p-amino-.alpha.-alkylstyrene or p-amino-.beta.-alkylstyrene. Other 
polyunsaturated monomers may also be used; the only criterion being that 
one double bond of the monomer is substantially more reactive than the 
other double bond. 
The dispersant monomer that may be used to produce the present lubricant 
may be a dialkylamino methacrylamide or acrylamide or methacrylate or 
acrylate where one amino group is a primary or secondary amine and the 
other amino group is a secondary or tertiary amine. 
The acrylate or methacrylate monomers and alkyl acrylate or methacrylate 
monomers of the present invention are conveniently prepared from the 
corresponding acrylic or methacrylic acids or their derivatives. These 
acids can be synthesized using conventional methods and techniques. For 
example, acrylic acid is prepared by the acidic hydrolysis and dehydration 
of ethylene cyanohydrin or by the polymerization of .beta.-propiolactone 
and the destructive distillation of the polymer to form acrylic acid. 
Methacrylic acid is readily prepared by the oxidation of a methyl 
.alpha.-alkyl vinyl ketone with metal hypochlorites; the dehydration of 
.alpha.-hydroxyisobutyric acid with phosphorus pentoxide; or the 
hydrolysis of acetone cyanohydrin. 
The alkyl acrylate or methacrylate monomers of the present invention are 
conveniently prepared by reacting the desired primary alcohol with the 
acrylic acid or methacrylic acid in a conventional esterification 
catalyzed by acid, preferably p-toluene sulfonic acid and inhibited from 
polymerization by MEHQ or hydroquinone. Suitable alkyl acrylates or alkyl 
methacrylates contain from about 1 to about 30 carbon atoms in the alkyl 
carbon chain. Typical examples of starting alcohols include methyl 
alcohol, ethyl alcohol, butyl alcohol, octyl alcohol, iso-octyl alcohol, 
isodecyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, 
capryl alcohol, lauryl alcohol, myristyl alcohol, pentadecyl alcohol, 
palmityl alcohol or stearyl alcohol. It is to be noted that all of the 
starting alcohols described above can be reacted with acrylic acid or 
methacrylic acid to form desirable acrylates or methacrylates. 
The copolymers useful in the practice of this invention can be prepared in 
a conventional manner by bulk, solution or emulsion polymerization methods 
using known catalysts. Thus, the copolymers utilized by this invention can 
be prepared from the corresponding monomers with a diluent such as water 
in a heterogeneous system, usually referred to as emulsion or suspension 
polymerization, or in a homogenous system with a solvent such as toluene, 
benzene, ethylene dichloride, or an oil solvent which is normally referred 
to as solution polymerization. Solution polymerization in benzene, toluene 
or an oil solvent having similar chain transfer activity is the preferred 
method used in forming the copolymers disclosed herein, because this 
method and solvent produce the preferred copolymers characterized by a 
relatively high molecular weight. Solvents normally comprise from about 10 
to about 50 weight percent based on the weight of the copolymer. 
The polymerization of the monomers uses suitable catalysts which include 
peroxide type free radical catalysts such as benzoyl peroxide, lauroyl 
peroxide, or t-butylhydroperoxide; and free radical catalysts such as 
2,2-azobisisobutyronitrile. The catalysts, when used, are employed in 
concentrations ranging from a few hundredths of a percent to two percent 
by weight of the monomers. The preferred concentration is from about 0.2 
to about 1.0 percent by weight of the monomers. 
Copolymerization of the monomers used herein takes place over a wide 
temperature range depending upon the particular monomers and catalyst 
utilized in the reaction. For example, copolymerization can take place at 
temperatures as low as -103.degree. F(-75.degree. C) or lower when 
metallic sodium in liquid ammonia is used as the catalyst. However, the 
copolymerization reaction is generally carried out at temperatures ranging 
from about 77.degree. F.(25.degree. C.) to about 302.degree. 
F.(150.degree. C.) when a catalyst such as 2.2-azobisisobutyronitrile is 
used. The copolymerization reaction is preferably carried out in an inert 
atmosphere, for example, argon or nitrogen to favor the formation of 
copolymers having relatively high viscosities and molecular weights. 
Preferably, the copolymerization reaction is carried out to substantial 
completion so that the finished product is essentially comprised of the 
ratio of monomers introduced into the vessel. Normally, a reaction time of 
from about 1 to about 72 hours, preferably from about I to about 50 hours, 
is sufficient to complete the copolymerization process. 
The copolymers disclosed herein have an average molecular weight of greater 
than about 20,000, especially a molecular weight range of from about 
20,000 to about 300,000, preferably from about 80,000 to about 200,000. 
The molecular weight of the copolymer can conveniently be determined using 
conventional techniques. 
The terpolymers of this invention may be formed from 
(1) a first monomer 
##STR2## 
(2) a second monomer 
##STR3## 
and optionally (3) a third monomer 
##STR4## 
wherein A is --NH--, --)--, or --S--; 
R.sup.1 is H or a lower alkyl group; 
R.sup.2 is an unsaturated alcohol, amine thiol or phenol residue; 
R.sup.3 is a (C.sub.1 -C.sub.20) alkyl group; 
R.sup.4 is an alkylene group (--CH.sub.2 --).sub.x, x=0 to 10 
R.sup.5 and R.sup.6 are alkyl, alkaryl, aralkyl, aryl or arylene groups. 
Illustrative of the first monomers which may be employed are those provided 
below in Table I, the first listed being preferred. 
TABLE I 
______________________________________ 
Neodol 25L methacrylate 
Alfol 1620 SP methacrylate 
Neodol 25L acrylate 
Alfol 1620 SP acrylate 
lauryl methacrylate 
lauryl acrylate 
lauryl ethacrylate 
decyl methacrylate 
decyl acrylate 
undecyl methacrylate 
undecyl acrylate 
tridecyl methacrylate 
tridecyl acrylate 
myristyl methacrylate 
myristyl acrylate 
pentadecyl methacrylate 
pentacecyl acrylate 
isodecyl methacrylate 
isodecyl acrylate 
stearyl methacrylate 
stearyl acrylate 
cetyl methacrylate 
cetyl acrylate 
methyl methacrylate 
methyl acrylate 
butyl methacrylate 
butyl acrylate 
______________________________________ 
The NMA and the AMA monomers described above are respectively derived from 
Neodol 25L and Alfol 1620 SP which are trade names for technical grade 
alkanols, respectively, of Shell Chemical Co and Continental Oil Co. of 
the following typical analyses. 
______________________________________ 
Neodol 25L Typical Approx. Homolog 
(Synthetic Lauryl Alcohol) 
Distribution, wt % 
______________________________________ 
Lighter than C.sub.12 OH 
4 
C.sub.12 OH 24 
C.sub.13 OH 24 
C.sub.14 OH 24 
C.sub.15 OH 13 
C.sub.16 OH 2 
______________________________________ 
______________________________________ 
Alfol 1620 SP 
(Synthetic Stearly Alcohol) 
______________________________________ 
C.sub.14 OH and lighter 
4 
C.sub.16 OH 55 
C.sub.18 OH 28 
C.sub.20 OH 9 
______________________________________ 
The third monomer which may be employed in practice of the process of this 
invention may be characterized by the formula 
##STR5## 
In the above formula R.sup.5 or R.sup.6 may be hydrogen or a hydrocarbon 
selected from the group consisting of alkyl, aralkyl, cycloalkyl, aryl, 
and alkaryl, including such radicals when inertly substituted. When 
R.sup.5 or R.sup.6 is alkyl, it may typically be methyl, ethyl, n-propyl, 
isopropyl, n-butyl, isobutyl, sec-butyl, amyl, octyl, decyl, octadecyl, 
etc. When R.sup.5 or R.sup.6 is aralkyl, it may typically be benzyl, 
betaphenyethyl, etc. When R.sup.5 or R.sup.6 is cycloalkyl, it may 
typically be cyclohexyl, cycloheptyl, cyclooctyl, 2-methylcycloheptyl, 
3-butylcyclohexyl, 3-methylcyclohexyl, etc. When R.sup.5 or R.sup.6 is 
alkaryl, it may typically be tolyl, xylyl, etc. When R.sup.5 or R.sup.6 
may be inertly substituted i.e. it may bear a non reactive substituent 
such as alkyl, aryl, cycloalkyl, ether, etc. Typically inertly substituted 
R.sup.5 or R.sup.6 groups may include 2-ethoxyethyl, carboethoxymethyl, 
4-methyl cyclohexyl, etc. The preferred R.sup.5 or R.sup.6 groups may be 
lower alkyl, i.e., (C.sub.1 -C10 ) alkyl groups including e.g. methyl, 
ethyl, n-propyl, i-propyl, butyls, amyls, hexyls, octyls, decyls, etc. 
R.sup.5 or R.sup.6 may preferably be methyl. 
In the above formula, R.sup.4 may be a hydrocarbon group selected from the 
group consisting of alkylene, aralkylene, cycloalkylene, arylene and 
alkarylene, including such radicals when inertly substituted. When R.sup.4 
is alkylene, it may typically be methylene, ethylene, n-propylene, 
iso-propylene, n-butylene, i-butylene, sec-butylene, octylene, decylene, 
octadecylene, etc. When R.sup.4 is aralkylene, it may typically be 
benzylene, beta-phenylethylene, etc. When R.sup.4 is cycloalkylene, it may 
typically be cyclohexylene, cycloheptylene, cyclooctylene, 
2-methycycloheptylene, 3-butylcyclohexylene, 3-methylcyclohexylene, etc. 
When R.sup.4 is arylene, it may typically be phenylene, naphthylene, etc. 
When R.sup.4 is alkarylene, it may typically be tolylene, xylylene, etc. 
When R.sup.4 is arylene, it may typically be phenylene, naphthylene, etc. 
When R.sup.4 is alkarylene, it may typically be tolylene, xylylene, etc. 
R.sup.4 may be inertly substituted i.e. it may bear a non-reactive 
substituent such as alkyl, aryl, cycloalkyl, ether, etc. Typically inertly 
substituted R.sup.4 groups may include 2-ethoxyethylene, 
carboethoxymethylene, 4-methyl cyclohexylene, etc. The preferred R.sup.4 
groups may be lower alkylene, i.e., (C.sub.1 -C.sub.10) alkylene, groups 
including e.g. methylene, ethylene, n-propylene, i-propylene, butylene, 
amylene, hexylene, octylene, decylene, etc. R.sup.4 may preferably be 
propylene--CH.sub.2 CH.sub.2 CHJ.sub.2 --. 
In the above formula, A may be --O--, --S--, or preferably --NH--. 
Typical third monomers may be as set forth below in Table II, the first 
listed being preferred. 
TABLE II 
______________________________________ 
N,N-dimethylaminopropyl 
methacrylamide 
N,N-diethylaminopropyl 
methacrylamide 
N,N-dimethylaminopropyl 
acrylamide 
N,N-diethylaminopropyl 
acrylamide 
N,N-dimethylaminoethyl 
acrylamide 
N,N-diethylaminoethyl 
acrylamide 
N,N-dimethylaminoethyl 
methacrylamide 
N,N-dimethylaminoethyl 
acrylamide 
N,N-dimethylaminoethyl 
thiomethacrylamide 
______________________________________ 
The first monomer which is polyunsaturated may be an acrylate or 
methacrylate represented by the following formula: 
##STR6## 
where R.sup.1 is H or a alkyl group and R.sup.2 is an amine or alcohol 
residue such as but not exclusively: 
______________________________________ 
oleyl alcohol 
oleyl amine 
allyl alcohol 
allyl amine 
hydroxy styrene 
amino styrene 
hydroxy -.alpha.-methylstyrene 
amino -.alpha.-methylstyrene 
hydroxy -.beta.-methylstyrene 
amino -.beta.-methylstyrene 
______________________________________ 
and other hydroxy and amino substituted olefins capable of reaction with 
aromatic nitroso compounds after polymerization. 
(b) a diolefin wherein the diolefin has double bonds of different 
reactivities such as: 
allyl styrene 
oleyl styrene 
and other olefinically substituted styrenes and alkyl styrenes; or 
(c) a polyunsaturated heterocycle capable of containing a reactive double 
bond after initial polymerization, such as: 
##STR7## 
The second monomer when prepared commercially may in fact be a mixture 
obtained by use of a crude alcohol mixture during esterification. The 
carbon number of the monomer is that of the ester which is the predominant 
ester in the monomer. Commonly, the carbon number may be the weight 
average carbon number of the alcohol-derived alkyl group making up the 
esters. 
The three component terpolymers of this invention may be prepared by 
contacting a mixture consisting essentially of first monomer, second 
monomer, and optionally the third monomer in the presence of a 
polymerization initiator-catalyst and chain transfer agent in an inert 
atmosphere in the presence of diluent. Typically 75-98 parts, preferably 
90-98, say 92 of second monomer and 1-15 parts, preferably 2-10, say 4 
parts of first monomer and 1-15, preferably 2-10, say 4 parts of third 
monomer may be added to the reaction operation. 
The polymerization solvent may typically be an inert hydrocarbon, 
preferably hydrocarbon lubricating oil (typically N 100 pale oil) which is 
compatible with or identical to the lubricating oil in which the additive 
is to be employed present in amount of 5-50 parts, preferably 20-50 parts, 
say 40 parts per 100 parts of total reactants. 
The Polymerization initiator-catalyst may be 2,2-azobisisobutyronitrile 
(AIBN), or a peroxide such as benzoyl peroxide, present in amount of 
0.05-0.25 parts, preferably 0.1-0.2 parts, say 0.16 parts. Chain 
terminator may typically be (C.sub.8 -C.sub.12) mercaptans, typified by 
lauryl mercaptan, present in amount of 0.10 parts, preferably 0.02-0.08 
parts, say 0.06 parts. 
Polymerization is carried out with agitation at 25.degree. C.-150.degree. 
C., preferably 50.degree. C.-100.degree. C., say 83.degree. C, and 0-100 
psig, preferably 0-50 psig, say 0 psig for 1-8 hours, say 3 hours. 
Reaction may be continued until two identical refractive indices are 
recorded. 
The intermediate polymer is characterized by a molecular weight Mn of 
preferably 20,000-250,000, say 80,000. The component weight ratio of 
first, second and third monomer may be 75-98: 1-5: 1-15 say 92:4:4. 
The polydispersity index (Mw/Mn) of these oil-soluble polymers may be 1-5, 
preferably 1.5-4, say 2.3. 
In a typical reaction, the monomers are charged to the reactor together 
with polymerization solvent followed by chain terminator. Agitation and 
inert gas (e.g. nitrogen) flow are initiated. Polymerization initiator is 
added and the reaction mixture is heated to reaction temperature at which 
it is maintained until the desired degree of polymerization is attained. 
Diluent oil (if employed) is added to yield a lube oil concentrate 
containing about 25-80 wt%, preferably 35-70 wt%, say 40 wt% of the 
intermediate terpolymer. 
The intermediate terpolymers prepared may be characterized by the formula: 
##STR8## 
The intermediate polymer is then reacted with a reagent capable of reacting 
with the remaining unsaturated groups in the polymer and imparting 
antioxidant properties. Particularly, effective reagents are aromatic 
nitroso derivatives of hindered phenols and amines such as: 
(a) 2,6-ditert-butyl-I,4-nitrosophenol 
##STR9## 
(b) nitrosoaromatic amines such as 4nitrosodiphenylamine 
##STR10## 
(c) 4-nitroso dimethylanaline 
##STR11## 
According to this invention, a hydrocarbon lubricating oil composition may 
comprise a major effective portion of a hydrocarbon lubricating oil and a 
minor effective portion of the additive polymer. The minor effective 
portion may typically be 0.01-10.0 parts. Preferably 0.1-8 parts, say 5.0 
parts, per 100 parts of hydrocarbon lubricating oil. The total composition 
may also contain other additives typified by oxidation inhibitors, 
corrosion inhibitors, antifoamants, detergents, dispersants, etc. 
Typical of the supplementary detergent-dispersants which may be present may 
be alkenylsuccinimides derived from polyisobutylene (Mn of 700-5000) 
overbased calcium alkyl aromatic sulfonate having a total base number of 
about 300; sulfurized normal calcium alkylphenolate; alkenyl succinimides; 
etc. as disclosed in U.S. Pat. Nos. 3,087,956; 3,549,534; and 3,537,966. 
Typical of the antioxidants which may be present may be zinc or cadmium 
dialkyl dithiophosphates or dialkyldithiophosphates; alkylated diphenyl 
amines; sulfurized alkylphenols and phenolates, hindered phenols, etc. 
Typical of the corrosion inhibitors which may be present may be zinc 
dialkyldithiophosphates, basic calcium, barium, or magnesium, sulfonates; 
calcium, barium, and magnesium phenolates, etc. 
It is a feature of this invention that the novel lubricating oil 
compositions may be characterized by improved pour point when the novel 
additives are present in amount of 0.05-5.0 wt%, preferably 0.1-0.7 wt%, 
say 0.3 wt% of the lubricating oil. 
Typically it may be possible to treat a base lubricating oil of pour point 
of -12.degree. C., by addition of only 0.3 wt% of additive to yield a 
product having a pour point of minus 36.degree. C. Pour point is commonly 
measured by ASTM D-97. 
When used as a pour point depressant, it is preferred that the molecular 
weight (Mn) of the polymer be 20,000-120,000, preferably 20,000-80,000, 
say 20,000. 
It is also a feature of this invention that the novel additives may be used 
as dispersancy improvers when the third monomer is present, in lubricating 
oil compositions in effective amount of 3.0 wt%-10.0 wt%, preferably 4.0 
wt% to 8.0 wt%, say 5.0 wt%. When dispersancy is primarily desired, the 
molecular weight (Mn) of the polymer may be 20,000-120,000, say 80,000. 
The novel additives of this invention may impart viscosity index 
improvement to lubricating oils when present in amount to 0.25 wt%-10.0 
wt%, preferably 2 wt%-8 wt%, say 5.0 wt%. When they are employed primarily 
as viscosity index improvers, the molecular weight (Mn) may be 
20,000-150,000, preferably 40,000-120,000, say 80,000. The Viscosity Index 
is measured by ASTM D-2270. 
It is a feature of the terpolymer additives of this invention (which 
consist essentially of first, second and third monomer components) that 
they unexpectedly provide improvements in pour dispersancy, dispersancy, 
and viscosity index, i.e. they may be used, either in whole or in part, to 
provide all of these functions. When it is desired to utilize the novel 
additive to provide all three of these functions, it is preferred that the 
additive be present in amount of 1.0-8.0 wt%, say 5.0 wt% of the 
lubricating oil composition. In this instance the molecular weight Mn may 
be 20,000-120,000, preferably 40,000-90,000, say 80,000.

In order to show the advantages of the present invention the following 
Examples are provided as being representative of the best mode of how to 
practice the invention described herein and not intended to limit the 
scope thereof. 
EXAMPLE I 
Preparation of Oleyl Acrylate 
To a 500 ml round bottom flask equipped with a stirrer, condenser, water 
trap and thermometer, was added oleyl alcohol (100 g, 0.373 moles), 
acrylic acid (27 g, 0.373) moles), p-toluenesulfonic acid monohydrate (1g, 
1 wt%, hydroquinone (0.2 g, 0.2 wt%) and xylene (I00 ml). The reaction 
mixture was heated to reflux and maintained until no more water was 
collected (.about.4 hrs). The xylene solution was then concentrated to 
about half of its original volume. The crude product was then washed 
successively with water, saturated sodium bicarbonate solution, and then 
again with water. The organic solution was dried over sodium sulfate, 
filtered and the solvent evaporated under reduced pressure. The product 
was stabilized by 0.01 wt% of MEHQ. The yield was 80%. 
EXAMPLE II 
Preparation of 2,6-ditert-butyl-4-nitrosophenol 
In a 500 ml round flask equipped with a thermometer, stirrer and nitrogen 
inlet was added 2,6-ditertbutylphenol (50 g, 0.243 moles) and ethanol 
(95%, I00 ml). The solution was stirred until all of the phenol dissolved. 
The solution was then cooled to 0.degree. C and concentrated hydrochloric 
acid (26.3 g, 0.267 moles) was slowly added. A solution of sodium nitrite 
(17.56 g, 0.254 moles) in water (75 ml) was then added dropwise so as to 
keep the temperature of the reaction between 0 .degree.and 10.degree. C. 
(1 hr). The solution became quite thick and more ethanol was added 
accordingly, for efficient stirring. After the addition was completed, the 
reaction mixture was stirred for 1 hr and it was then poured into a beaker 
of ice water (.about.5 L). The yellow green precipitate was filtered off 
washed, with water and air dried. The yield was 98 wt%. (210-213.degree. 
C.). 
EXAMPLE III(a) 
Preparation of the Base Dispersant Polymethacrylate 
To a 1000 ml resin kettle equipped with a thermocouple, thermometer, 
condenser and heavy duty stirrer, was added N,N-dimethylaminopropyl 
methacrylamide (8 g,4 wt.%), oleyl acrylate (8 g,4 wt.%), butyl 
methacrylate (20g, 10 wt.%), neodol 25L methacrylate (152 g, 76 wt.%), 
alfol SP 1620 methacrylate (12 g, 6 wt.%) and an oil solvent (NI00 Pale 
Oil, 43 g). The reaction mixture was stirred and purged by nitrogen 
ebullition for 30 min at 20 ml/min. The mixture was then heated to 
80.degree. C by means of an heat lamp, and dodecyl mercaptan (0.2 g) and 
AIBN (0.4 g) were then added. After 4 hrs, the reaction temperature was 
increased to 100.degree. C. and maintained for 1 hr to destroy any excess 
AIBN. 
The intermediate polymer product is typically diluted in the reaction 
vessel with N55 Pale Oil (214 g) to give a final concentration of 
.about.40% in oil. 
EXAMPLE III(b) 
Preparation of Non-Dispersant Base PMA 
Using the procedure of Example III(a) above, the following monomers were 
polymerized to prepare the nondispersant base polymer. 
______________________________________ 
Monomer Wt. % 
______________________________________ 
Oleyl acrylate 4.0 
Butyl Methacrylate 10.0 
Neodol 25L Methacrylate 
80.0 
Alfol 1620 SP Methacrylate 
6.0 
______________________________________ 
EXAMPLE IV 
Preparation of the Dispersant - Antioxidant PMA (DAOPMA) 
In a 250 ml round bottom flask equipped with thermometer, stirrer and 
nitrogen inlet, was added the base dispersant polymethacrylate of Example 
III(a) (I50 g) and the 2,6-ditert-butyl-4-nitrosophenol. The mixture was 
stirred and heated at 120.degree. C. for 30 min. The temperature was then 
increased to 160.degree. C. and maintained for an additional hour while 
water was removed from the system. The product was cooled to about 
60.degree. C. and isolated. 
EXAMPLE V 
Preparation of the Dispersant-Antioxidant PMA (DAOPMA) 
In a 250 ml round bottom flask equipped with thermometers, stirrer and 
nitrogen inlet, was added the base dispersant polymethacrylate of Example 
III(a) (100 g, 4.96 mmoles) and the 4-nitroso diphenylamine (I g, 4.97 
mmoles). The reaction mixture was stirred and heated at 120.degree. C. for 
30 minutes. The temperature was then increased to I60.degree. C. and 
maintained for an additional hour while water was removed from the system. 
The product was cooled to about 60.degree. C. and then isolated. 
EXAMPLE VI 
Preparation of Antioxidant Polymethacrylate (AOPMA) 
In a 250 ml round bottom flask equipped with thermometer, stirrer and 
nitrogen inlet, was added the base polymethacrylate of Example III(b) (100 
g, 4.96 mmoles) and the 4-nitroso diphenylamine (1 g, 4.97 mmoles). The 
reaction mixture was stirred and heated at 120.degree. C. for 30 minutes. 
The temperature was then increased to 160.degree. C. and maintained for an 
additional hour while water was removed from the system. The product was 
cooled to about 60.degree. C and then filtered. 
______________________________________ 
Example III (a) 
Example IV 
______________________________________ 
Typical Analyses 
Kin. Vis. 40.degree. C. 
89.6 88.5 
Kin. Vis. 100.degree. C. 
12.26 12.22 
Refractive Index 80% conc. 
1.4668 -- 
(48.3.degree. C.) 
% Nitrogen 0.37 
Additional Tests 
Pour Point (1) -36.degree. C. 
______________________________________ 
(1) A 5% blend of polymer in Base oil with a pour point of -13.degree. C. 
Evaluation of Antioxidant Properties 
A Bench Oxidation Test (BOT) was used to measure the antioxidant properties 
of the polymer. This test measures the relative increase of the carbonyl 
absorption band of 1710 cm.sup.-1 of an oxidized oil, over that of the 
starting material. 
BOT TEST PROCEDURE 
The test is conducted in a 2 L, 4-neck resin kettle equipped with a 
thermometer, condenser, gas bubbling tube and a mechanical stirrer. The 
polymer (3.75 wt% of a 40 wt% concentrate) was added along with -235 g of 
SNO-7 oil. The reaction mixture was stirred and purged with nitrogen for 
30 min. The solution was then heated to 150.degree. C. and initial samples 
were taken (0 hr. samples). The oxidation is started by switching from a 
nitrogen purge to one of air at a rate of 500 ml/min. The stirring rate is 
kept between 675 and 700 rpm's. Samples are taken periodically using a 
syringe and evacuated test tubes. They are then quickly stored in a 
refrigerator to quench the oxidation. BOT DIR values are obtained by using 
a Differential Infrared technique (DIR) in which the carbonyl absorption 
band at 1710 cm.sup.-1 of the zero hour sample, is subtracted from that of 
the final product (144 hrs.). 
The SNO-7 will give a DIR of --7 if no antioxidant is used, so values less 
that 7 are considered indicative of antioxidant properties. In Example 1, 
a DIR of 1.77 was obtained. The dispersant properties of the polymer 
product were determined by a Bench Sludge Test (BST) as described below. 
Evaluation of Dispersancy Properties 
The dispersancy of the additives was evaluated in the Bench Sludge Test 
(BST) which measures the ability of a dispersant to solubilize particles 
in the oil. This test is conducted by heating the test oil mixed with a 
synthetic hydrocarbon blowby and a diluent oil at a fixed temperature for 
a fixed time period. After heating, the turbidity of the resulting mixture 
is measured. A low percentage turbidity (0-10) is indicative of good 
dispersancy while an intermediate value (20-40) indicates intermediate 
dispersancy and a high value (40-100) indicates an increasingly poor 
dispersancy. The additives were tested at a 4.85 wt% treating dosage in an 
SAE 10W-30 formulation and compared to good, fair and poor references as 
provided below in Table IV. 
__________________________________________________________________________ 
BOT AND BST RESULTS 
% AO % DISPERSANT 
POLYMER CONCENTRATION 
GRAFT 
GRAFT DIR BST (1) 
__________________________________________________________________________ 
Example III (a) 
1.5% Polymer 
0.0 4.0 17.21 
37.5 
Base polymer 
Example IV 
1.5% Polymer 
4.0 4.0 8.21 
32.0 
DAOPMA 
Example V 
1.5% Polymer 
4.0 4.0 0.00 
35.0 
DAOPMA 
Example VI 
1.5% Polymer 
4.0 0.0 0.72 
93.4 
AOPMA 
__________________________________________________________________________ 
(1) BST results were obtained on 4.85 wt % concentrates of the polymer 
concentrate in a fully formulated oil containing no dispersant. 
In the formulation of an oil, a low pour point is important. According to 
the present invention, the pour point may be lowered from about 
-25.degree. C. to about -40.degree. C. The procedure for evaluating the 
pour point depressant properties is provided below. 
Evaluation of Pour Point Depressant Properties 
The pour point of an oil is measured by the ASTM D-97 test. Pour point 
depressants are evaluated at how much they depress the pour point of an 
oil. A particular base oil has a pour point of -b 12.degree. C. The 
addition of a commercial pour point depressant at 5.0 wt% effectively 
lowers the pour point of the base oil to -30.degree. C. The product of the 
Example, however, effectively lowers the pour point of the base oil to 
about -42.degree. C. when used at 5.0 wt%.