Note: Descriptions are shown in the official language in which they were submitted.
Z7~
BACKGROUND OF THE INVENTION
This invention relates to improved lubricating oil
compositions. More particularly, this invention relates
to lubricating oil compositions which include solid materials
to enhance the properties of such compositions.
Oil compositions are conventionally used to lubricate
internal combustion engines, for example, such engines ~ -
which power motor vehicles. Previous studies have indicated
that the inclusion of certain solid materials, e.g.,
graphite, in these oil compositions improves the engine's
fuel efficiency. For example, studies reported in "Stable
Colloid Additives for Engine Oils - Potential Improvement
in Fuel Economy", James E. Bennington et al, Society
of Automotive Engineers, Fuels and Lubricants Meeting,
Houston, Texas, June 3-5, 1975, indicate that a gasoline
mileage improvement of between 3 to 5 percent is obtained
by adding one percent graphite to a conventional lubricating
oil composition. Such improvement in fuel economy is
particularly valuable in view of, for example, the short
supply of such fuels.
.~.,~
'727Z
However, other criteria must be met by lubricating
oil compositions in order to be effective in modern internal
combustion engines. For example, such compositions are
required to meet certain specifications with regard to
tendency to form deposits, e.g., varnish, sludge and
the like, on engine components. The presence of the - -
solid l~bricants in these compositions tends to increase
these deposit forming tendencies.
A lubricating oil composition containing at least
one of certain solid lubricants and having acceptable
deposit forming characteristics is clearly desirable.
Therefore, one object of the present invention is
to provide an improved lubricating oil composition.
Another object of this invention is to provide a
solid particles-containing lubricating oil composition
having reduced deposit forming tendency.
A still further object of the invention is to provide
an improved method of lubricating an internal combustion
engine~ Other objects and advantages of the present
invention will become apparent hereinafter.
SUMMARY OF THE INVENTION
An improved lubricating oil composition has now
been developed. This composition comprises a major amount
by weight of oil of lubri~ating viscosity; a minor amount
by weight of solid particles effective to improve the
lubricating properties of the composition; and a minor
amount by weight of at least one of certain nitrogen
containing mixed ester of a carboxy-containing interpolymer.
.
l:lJJ7;~7Z
A preferred nitrogen containing mixed ester of a
carboxy containing interpolymer is a polymer having a
reduced specific viscosity in the range of about
0.05 to about 2, and being characterized by the
presence within its polymeric structure of at least one
of each of three pendant polar groups: (A) a relatively
high molecular weight carboxylic ester group having at
least about 8 aliphatic carbon atoms in the ester radical,
(B) a relatively low molecular weight carboxylic ester
group having no more than about 7 aliphatic carbon atoms
in the ester radical, and (C) a carbonyl-polyamino group
derived from at least one compound selected from the group
consisting of (1) a polyamino compound having one primary
or secondary amino group, (2) hydrazine or a hydrocarbon
substituted hydrazine and (3) mixtures thereof. Preferably,
the molar ratio of (A):(B):(C): is about
(60-90):(10-30):(2-25),
;~ more preferably about
(60-90):(10-30):(2-15).
More preferably, the present ester of a carboxy
containing interpolymer is substantially free of titratable
acidity.
The incorporation of such amounts of these interpolymer
esters into the present solid particles containing compositions
has been found to provide a surprising degree of reduction
in detrimental deposit formulation, e.g., on internal
combustion engine components lubricated by the present
compositions.
--4--
1~72~2
DETAILED DESCRIPTION ~F THE INVENTION
The oils used in the compositions of the present
invention are those conventionally used in lubricant manufacture.
The suitable lubricating oils include those having a viscosity
within the range of about 50 SUS to about 2000 SUS at
100F. These oils may be refined or otherwise processed
to produce an oil having the desired quality. Although
mineral oils are preferred, the oil may be synthetic in
nature. The oil used in the present invention is preferably
a mineral oil having a viscosity of about 100 SUS to about
1000 SUS at 100F. Combinations of two or more different
oils in a single lubricating composition are within the
scope of the present invention. The lubricating oil comprises
a major proportion preferably at least about 60 percent
still more preferably at least about 70 percent, by weight
of the total composition.
The present compositions include a minor amount by
weight of solid particles effective to improve the lubricating
properties of the compositions. Preferably, a ma~or portion,
by weight, and more preferably substantially all, of such
solid particles, have a maximum transverse dimension in
the range of about 1 millimicron to about 2 microns, and
most preferably in the range of about 1 millimicron to
about 1 micron. Suitable solid particles for use in the
present invention include those materials known to provide
improved lubricating properties to lubricating oil compositions.
Such solid particles include, for example, graphite, molybdenum
disulfide, zinc oxide, tungsten disulfide, mica, boron
nitrate, borax silver sulfate, cadmium iodide, lead iodide,
~1~7;~2
barium flouride, tin sulfide, mixtures thereof and the
like. The solid particles useful in the present compositions
are preferably selected from the group consisting of graphite,
molybdenum disulfide, zinc oxide, and mixtures thereof;
more preferably from the group consisting of graphite,
molybdenum disulfide and mixtures thereof; and most preferably,
graphite.
The solid particles are preferably present in the
present compositions in an amount of about 0.05~ to about
5%, more preferably about 0.1% to about 2~, by weight
of the total composition. The solid particles component
of the present composition is preferably prepared as a
colloidal suspension, in, for example, a conventional
lubricating oil and/or at least one conventional lubricating
oil detergent. For example, such colloidal suspensions
or concentrates may contain about 2% to about 25% or more,
by weight of such solid particles.
Any conventional lubricating oil detergent may be
used to aid in stabilizing these colloidal suspensions
of the presently useful solid particles. Such detergents
are often characterized as comprising at least one surface
active compound which, when included in a lubricating
oil composition tends to inhibit solid contaminants, e.g.,
combustion by-products present in the engine's lubricating
oil, from adhering to metallic surfaces of engine components.
Although both ash-containing, metal-based detergents and
ashless detergents are useful as such solid particles-
containing suspension, the ashless detergents are preferred.
~Z
There are many examples of ash-containing, metal-
based detergents which are suitable in such solid particles-
containing suspension. The ashless detergents preferred
for use are compounds which comprise an oil-solubilizing
tail and a polar detergent head. Many ashless detergents
fitting this general description are known to the art
and are commercially available.
Specific examples of this type of ashless detergent
include the polyamino-polyalkylene alkenyl succinimides.
Amine salts of alkyl phosphoric acids, are also suitable.
Polyamine derivatives of long chained hydrocarbons may
also be used. Reaction products of alkylene polyamines
with long chain alkenyl succinic anhydrides and long chain
~; esters of Mannich bases are suitable detergents. As can
be seen, the required polarity may be supplied by groups
containing, for example, oxygen, sulfur, phosphorous,
nitrogen and mixtures thereof. All of these suitable
ashless detergents may be generally characterized as compounds
comprising at least one substantially hydrocarbon portion
of sufficient size to render the compound oil-soluble
and at least one non-metallic polar portion which when
attached to the hydrocarbon portion provides a substantial
part, often essentially all, of the detergent action.
To illustrate, specific examples of ashless detergents
suitable for use as solid particles stabilizers include
polyaminepolyalkylene alkenyl succinimines, long chain
polyamines, dihydrocarbon substituted polyamines, substituted-
phenol substituted polyamine products and mixtures thereof.
These compounds may be representèd by the following structures:
Z~Z
Polyamine-Polyalkylene Alkenyl Succinimides
,~
: R-CH C
~ N (R1N)m
C 2 ~ 2
Long Chain Polyamines
7 - Nl)m 2
; 2
Dihydrocarbon Substituted Polyamines
~ - N (Rl ~ N )n I ~ H
I I 1'
R3 R2 R
Substituted Phenol-Substituted Polyamine Products
R4 ~ C _ N [Rl - N ]m
ll 12 ~j~OH
27~ .
wherein R is a substantially hydrocarbon monovalent radical
containing from about 30 to about 250 carbon atoms; each
Rl is an independently selected substantially hydrocarbon
divalent radical containing from 1 to about 8 carbon atoms;
each R2 is independently selected from the group consisting
of H and substantially hydrocarbon monovalent radicals
containing from 1 to about 8 carbon atoms; each R2 is
an independen~ly selected substantially hydrocarbon monovalent
radical containing from about 15 to about 100 carbon atoms;
R4 is substantially hydrocarbon monovalent radical containing
from about 4 to about 30 carbon atoms; m is an integer
from 1 to about 10, preferably from 2 to about 10 and
n is an integer from zero to about 10, preferably from
about 2 to about 6.
It is preferred that R and R3 be alkenyl, preferably
selected from the group consisting of polypropenyl and
polyisobutenyl. It is preferred that each Rl be an independently
selected alkylene radical containing from 1 to aboùt 8,
more preferably from 2 to about 6, carbon atoms. Suitable
alkylene radicals from which each Rl may be independently
selected include methylene, ethylene, propylene, butylene,
hexylene, octylene and the like. Although each Rl may
be independently selected, it is preferred that for any
given ashless detergent all the Rl's contained therein
are the same radicals.
The substantially hydrocarbon monovalent radicals
from which each R2 may be independently selected each
contain from 1 to about 8, preferably from 1 to about
4, carbon atoms. These substantiaily hydrocarbon radicals
include alkyl, such as methyl, ethyl, propyl, butyl, hexyl,
octyl and the like, alkenyl, such as ethenyl, propenyl,
butenyl, hexenyl, octenyl and the like; aryl, alkaryl,
aralkyl, alkenaryl and aralkenyl, such as phenyl, methyl
phenyl, phenyl ethyl, ethenyl phenyl, phenyl ethenyl and
the like~
The substantially hydrocarbon radicals ~rom which
R4 is selected contain from 2 to about 30, preferably
~rom about 4 to about 24, carbon atoms. These radicals
may be straight chain or branchedj saturated or unsaturated,
aliphatic (including cycloaliphatic), aromatic or combinations
thereof. Examples of suitable radicals include alkyl
such as butyl, octyl, decyl, dodecyl, octadecyl, C24 alkyl
and the like; alkenyl such as butenyl, octenyl, dodecenyl,
octydecenyl, C24 alkenyl and the like; and aryl, alkaryl,
aralkyl, alkenaryl, aralkenyl such as phenyl, benzyl,
naphthyl, ethyl phenyl, decyl phenyl, octadecyl phenyl,
phenyl butyl, phenyl decyl, phenyl octadecyl, butenyl
phenyl, decenyl phenyl, octadecenyl phenyl, phenyl butenyl,
phenyl decenyl, phenyl octadecenyl and the like. More
preferably, R4 is selected from the group consisting of
alkyl and alkenyl containing from about 10 to about 24
carbon atoms.
Each R5 is preferably independently selected from
alkyl radicals containing from 4 to about 30, preferably
from about 8 to about 20, carbon atoms. Examples of radicals
from which each R5 may be independently selected include
amyl, octyl, decyl, octadecyl and the like. The
-10-
.
7272
I
,'1', ,
R5
portion of the substituted phenol substituted polyamine
acid salts may be replaced by, for example, alkylnaphthols
and similar derivatives of biphenyl, terphenyl, phenanthrene,
anthracene and the like.
The term "substantially" hydrocarbon radicals referred
to herein includes those radicals which are composed primarily ~: :
of carbon and hydrogen and also includes radicals which
contain, in addition, minor amounts of substituents, such
as oxygen, halide, sulfur, nitrogen and the like which
do not substantially affect the hydrocarbon character
of the radicals,
The specific ashless detergents noted above, as well
as other of the many suitable ashless detergent materials
and methods for preparing these materials are described
in the following United ~tates Patents: 3,237,614; 3,018,247;
3,513,093; 3,753,670; 3,008,993; 3,275,554; 3,~73,011;
3,574,576; 3,576,743; 3,578,422; 3,597,174; 3,369,110;
3,652,240; 3,655,351; 3,658,494; 3,658,495; 3,676,089;
3,701,640; 3,711,255; 3,717,447; ~,728,091; 3,746,520;
3,751,255; 3,756,793;~ 3,762,889; 3,764,281; 3,765j850;
3,773,479; 3,752,657; 3,753,670; 3,779,724 and 3,782,912.
., .
27~
An additional essential component of the lubricating
oil compositions of the invention is a minor amount,
by weight, of at least one of certain nitrogen-containing
esters of carboxy interpolymers. The preferred nitrogen-
containing mixed ester of a carboxy-containing interpolymer
is a polymer having a reduced specific viscosity of about
0.05 to about 2. The interpolymer is characterized by
the presence with its polymeric structure carboxylic
acid ester groups having at least 8 aliphatic carbon
atoms in the ester radical. The preferred interpolymer
is characterized by the presence within its polymeric
structure of at least one of each of three pendant polar
groups: (A) a relatively high molecular weight carboxylic
ester group having at least 8 aliphatic carbon atoms
in the ester radical, (B) a relatively low molecular
weight carboxylic ester group having no more than 7 aliphatic
carbon atoms in the ester radical, and (C) a carbonyl-
polyamino group derived from a polyamino compound having
one primary or secondary amino group, wherein the molar
ratio of (A):(B):(C) is about
(60-90):(10-30):(2-15)
It is preferred that the ester be a mixed ester, i.e.,
one in which there is the combined presence of both a
high molecular weight ester group and a low molecular
weight ester group, particularly in the ratio as stated
above.
-12-
ii~7;~7Z
In reference to the size of the ester groups, the
ester radical is represented by the formula
-C(O) (0~
and the number of carbon atoms is an ester radical is
thus the combined total of the carbon atom of the carbonyl
group and the carbon atoms of the ester group, i.e.,
the (OR') group.
Another important element of the nitrogen-containing ~ -
ester interpolymer is the presence of a carbonyl-polyamino
group derived from at least one nitrogen-containing compound
selected from the group consisting of (1) polyamino compound
having one primary or secondary amino group, (2) hydrazine
or a hydrocarbon-substituted hydrazine or (3) mixtures
thereof.
Still another important element of the present invention
is the extent of esterification in relation to the extent
of neutralization of the unesterfied carboxy groups of
the carboxy-containing interpolymer through the conversion
thereof to polyamino-containing groups. For convenience,
the relative proportions of the high molecular weight
ester group to the low molecular weight ester group and
to the polyamino group are expressed in terms of molar
ratios of about (60-90):(10-30:(2-15), respectively.
The more preferred ratio is about (70-80):(19-25):5.
It should be noted that the linkage described as the
carbonyl-polyamino group may be amide, imide, or amidine,
and inasmuch as any such linkage i5 contemplated within
the present invention, the term "carbonyl-polyamino"
-13-
: - .
~L~07;~
is employed to designate the amino group in defining
the interpolymers employed in the compositions of this
invention.
Still another important aspect of the mixed ester
interpolymer is the molecular weight of the interpolymer.
For convenience, the molecular weight is expressed in
terms of the "reduced specific "viscosity" of the interpolymer
which is a widely recognized means of expressing the
molecular size of a polymeric substance. As used herein,
the reduced specific viscosity (abbreviated as RSV) is
the value obtained in accordance with the formula
RSv=RelatiVe vi
Concentration
~; wherein the relative viscosity is determined by measuring,by means of a dilution viscometer, the viscosity of a ~ -
solution of one gram of the interpolYmer in 100 ml. of
acetone and the viscosity of acetone at 30 + 0.02C.
For purpose of computation by the above formula, the
concentration is adjusted to 0.4 gram of the interpolymer
per 100 ml. of acetone. A more detailed discussion of
the reduced specific viscosity, also known as the specific
viscosity, as well as its relationship to the average
molecular weight of an interpolymer, appears in Paul
J. Flory, Principles of Polymer Chemistry (1953 Edition)
pages 308 et seq.
7Z7;2
While interpolymers having a reduced specific viscosity
in the range of about 0.Q5 to about 2 are contemplated
for use in the present invention, the preferred interpolymers
are those having a reduced specific viscosity in the -
range of about 0.3 to about 1. In most instances, interpolymers
having a reduced specific viscosity in the range cf about
0.5 to about 1 are particularly useful.
From the standpoint of utility, as well as for commercial
and economical reasons, nitrogen-containing mixed esters
in which the high molecular weight ester group has about
from about 8 to about 24 aliphatic carbon atoms, the
low molecular weight ester group has from about 3 to
about 5 carbon atoms are preferred.
Specific examples of the high molecular weight carboxylic
ester group, i.e., the (OR') group of the ester radical
(i.e., -(O)(OR')) include heptyloxy, isooctyloxy, decyloxy,
dodecyloxy, tridecyloxy, pentadecyloxy, octadecyloxy,
eicosyloxy, tricosyloxy, tetracosyloxy, heptacosyloxy,
triacontyloxy, hentriacontyloxy, tetracontyloxy, etc.
~pecific examples of low molecular weight groups include
methyloxy, ethyloxy, n-propyloxy, isopropyloxy, n-butyloxy,
see-butyloxy, iso-butyloxy, n-pentyloxy, neo-pentyloxy,
n-henyloxy, cyclehexyloxy, cyclopentyloxy, 2-methy-butl-
oxy, 2,3-dimethyl-butyl-1-oxy, etc. In most instances,
alkoxy groups of suitable size comprise the preferred
high and low molecular weight ester groups. Polar substituents
may be present in such ester groups. Examples of polar
substituents are chloro, bromo, ether, nitro, etc.
-15-
2'~Z
The carbonyl polyamino group of the nitro~en-containing
esters of this invention comprise groups derived from
(1) polyamino compounds having one primary or secondary
amino group, and (2) hydrazine and/or hydrocarbon-substituted
hydrazine.
Preferred polyamino compounds for forming these
groups are primary-aminoalkyl substituted tertiary amines,
hetercyclic amines are particularly preferred.
Examples of the carbonyl polyamino group include
those derived from polyaminocompounds having one primary
; or secondary amino group and at least one monofunctional
amino group such as tertiary-amino or heterocyclic amino
group. Such compounds may thus be tertiary amino substituted
primary or secondary amines or other substituted primary
and secondary amines in which the substituent is derived
from pyrroles~ pyrrolidones, caprolactams, oxazolidones,
oxazoles, thiazoles, pyrazoles, pyrazolines,imidazoles,
imidazolines, thiazines, oxazines, diazines, oxycarbamyl,
thiocarbamyl, uracils, hydantoins, thiohydantoins, guanidines,
ureas, sulfonamides, phosphoramides, phenolthiazines,
amidines, etc. Examples of such polyamino compounds
include dimethyl-amino-ethylamine, dibutylamino-ethylamine,,
3-dimethyl-amino-1-propylamine, 4-methylethylamino-1-
butylamine, pyridyl-ethlamine, N-morpholino ethylamine,
tatrahydro-pyridyl-ethlamine, bis-(dimethylamino) propylamine,
bis-(diethylamino)ethylamine, N,N-dimethyl-p-phenylene
di-amine, piperidyl-ethylamine, l-aminoethyl pyrazone,
l-(methylamino)pyrazoline, l-methyl-4-aminooctyl pyrazole,
-16-
~10';~'7~ .
l-aminobutyl imidazole, 4-aminoethyl thiazole, 2-aminoethyl
triazine, dimethylcarbamyl propylamine, N-methyl-N-aminopropyl
acetamide, N-aminoethyl succinimide, N-methylamino maleimide,
N-aminobutyl-alpha-chlorosuccinimide, 3-aminoethyl uracil,
2-aminoethyl pyridine, orthy-aminoethyl-N,N-dimethylbenzene-
sulfamide, N-aminoethyl phenothiazine, N-aminoethylacetamidine,
l-aminophenyl-2-methyl-imidazoline, N-methyl-N-amino-
ethyl-S-ethyl-dithiocarbamate, etc. For the most part,
the polyamines are those which contain only one primary
amino or secondary-amino group and, preferably at least
one tertiary-amino group. The tertiary-amino group is
preferably a heterocyclic amino group. In some instances
polyamino compounds may contain up to about 6 amino groups
although, in most instances, they contain one primary
amino group and either one or two tertiary-amino groups.
The polyamino compounds may be aromatic or aliphatic
amines and are preferably heterocyclic amines such as
amino-alkyl-substituted morpholines, piperazines, pyridines,
benzopyrroles, quinolines, pyrroles, etc. They are usually
amines having from about 4 to about 30 carbon atoms,
preferably from about 4 to about 12 carbon atoms. Polar
substituents may likewise be present in the polyamines.
The carbonyl-polyamino groups of the nitrogen-containing
esters of this invention can also comprise the groups
derived from hydrazine and/or a hydrocarbon-substituted
hydrazine including, for example, the mono-, di-, tri-,
and tetrahydrocarbon-substituted hydrazines wherein the
hydrocarbon substituent is either an aliphatic or aromatic
~1~7~
substituent including, for example, the alkyl-, e.g.,
cyclic and/or acrylic groups, aryl-, alkylaryl-, aralkyl,
etc. The hydrocarbon substituents, generally, contain
up to about 24 aliphatic carbon atoms and preferably
up to about 12 aliphatic carbon atoms. The preferred
substituents, however, include, for example, phenyl,
alkylphenyl or an alkyl group wherein the alkyl is either
a methyl, ethyl, propyl, butyl, pentyl, octyl, cyclohexyl,
decyl or dodecyl, etc. Other examples of the hydrocarbon
groups include octyldecyl, behenyl, benzyl, heptaphenyl,
~ -naphthyl, ~ -naphthyl, butyl-naphthyl, oleyl, stearyl,
etc. Of the various hydrocarbon-substituted hydrazines,
a preferred class includes the N,N-dihydrocarbon-substituted
hydrazines, e.g., the dimethyl, diethyl, diphenyl and
dibutyl hydrazines.
The carboxy-containing interpolymers include principally
interpolymers of ~J~-unsaturated acids or anhydrides
such as maleic anhydride or itaconic anhydride with olefins
(aromatic or aliphatic) such as ethylene, propylene,
styrene, or isobutene. The styrene-maleic anhydride
interpolymers are especially useful. They are obtained
by polymerizing equal molar amounts of styrene and maleic
anhydride, with or without one or more additional inter-
polymerizable comonomers. In lieu of styrene, an aliphatic
olefin may be used, such as ethylene, propylene, isobutene.
In lieu of maleic anhydride, acrylic acid or methacrylic
acid or ester thereof may be used. Such interpolymers
are known in the art and need not be described in detail
here. Where an interpolymerizable comonomer is contemplated,
it should be present in a relatively minor proportion,
e.g., less that about 0.3 mole, usually less than about
-18-
11~7;~7Z
0.15 mole, per mole of either styrene or maleic anhydride.
Various methods of interpolymerizing styrene and maleic
anhydride are known in the art and need not be discussed
in detail here. For purpose of illustration, the inter~
polymerizable comonomers include the vinyl monomers such
as vinyl acetate, acrylonitrile, methyacrylate, methyl-
methacrylate, acrylic acid, vinyl methyl ether, vinyl
ethyl ether, vinyl chloride, isobutene or the like.
The preferred nitrogen-containing mixed esters are
most conveniently prepared by first esteri~ying the carboxy-
containing interpolymer with a relatively high molecular
weight alcohol and a relatively low molecular weight
alcohol to convert at least about 50% and no more than
about 98~ of the carboxy radicals of the interpolymer
lS to ester radicals and then neutralizing the remaining
carboxy radicals with a polyamine such as described above.
To incorporate the preferred amounts of the two alcohol
groups into the interpolymer, the ratio of the high molecular
weight alcohol to the low molecular weight alcohol used
in the process should be within the range of about 2:1
to about 9:1 on a molar basis. In most instances the
ratio is in the range of about 2.5:1 to about 5:1. More
than one high molecular weight alcohol or low molecular
weight alcohol may be used in the process; so also may
be used commercial alcohol mixtures such as the so-called
Oxo alcohols with comprise, for example, mixtures of
alcohols having from 8 to about 24 carbon atoms. A particularly
--19--
useful class of alcohols are the commercial alcohols
or alcohol mixtures having at least 7 aliphatic carbon
atoms including octyl alcohol, decyl alcohol, dodecyl
alcohol, tetradecyl alcohol, pentadecyl alcohol, eicosyl
alcohol, and octadecyl alcohol. Other alcohols useful
in the process are illustrated by those which, upon esteri-
fication, yield the ester groups exemplified above.
The extent of esterification, as indicated previously,
may range from about 50% to about 98% conversion of the
carboxy radicals of the interpolymer to ester radicals
to provide a partially esterified interpolymer. In a
preferred embodiment, the degree of esterification ranges
from about 75% to about 95%.
The esterification can be accomplished simply by
heating the carboxy-containing interpolymer and the alcohol
or alcohols under conditions typical for effecting esterification.
Such conditions usually include, for example, a temperature
of at least about 80C., preferably from about 150C.
to about 350C., provided that the temperature be below
the decomposition point of the reaction mixture, and
the removal of water of esterification as the reaction
proceeds. Such conditions may optionally include the
use of an excess of the alcohol reactant so as to facilitate
esterification, the use of a solvent or diluent such
as mineral oil, toluene, benzene, xylene or the like
and an esterification catalyst such as toluene sulfonic
acid, sulfuric acid, aluminum chloride, boron trifluoride-
-20-
72
triethylamine, hydrochloric acid, ammonium sulfate, phosphoric
acid, sodium methoxide or the like. The conditions and
variations thereof are well known in the art.
A particularly desirable method of effecting mixed
esterification involves first reacting the carboxy-containing
interpolymer with the relatively high molecular weight
alcohol and then reacting the partially esterified interpolymer
with the relatively low molecular weight alcohol and
then reacting the partially esterfied interpolymer with
the relatively low molecular weight alcohol. A variation
of this technique involves initiating the esterification
with the relatively high molecular weight alcohol and
before such esterification is complete, the relatively
low molecular weight alcohol is introduced into the reaction `
mass so as to achieve a mixed esterification. In either
event, a two-step esterification process whereby the
carboxy-containing interpolymer is first esterified with
the relatively high molecular weight alcohol so as to
convert from about 50~ to about 75% of the carboxy radicals
to ester radicals and then with the relatively low molecular
weight alcohol to achieve the finally desired degree
of esterification provides preferred interpolymers.
The unesterified carboxylic radicals in the partially
esterified interpolymer are then reacted with a nitrogen-
containing compound; e.g., polyamino compound and/or
hydrazine, to provide the nitrogen-containing esters
of the invention.
-21-
11~727Z
For example, the esterified interpolymer can be
treated with a polyamino compound in an amount so as
to neutralize substantially all of the unesterfied carboxy
radicals of the interpolymer. The neutralization is
preferably carried out at a temperature of at least about
80C., often from about 120C. to about 300C, provided
that the temperature does not exceed the decomposition
point of the reaction mass. In most instances the neutralization
temperature is between about 150C. and 250C. A slight
excess of the stoichiometric amount of the polyamino
compound is often desirable, so as to insure substantial
completion of neutralization, i.e., no more than about
2~ of the carboxy radicals initially present in the interpolymer
remained unneutralized and most preferably the resulting
ester is substantially free of titratable acidity.
The unesterified carboxylic radicals can also be
reacted with a small but effective amount of hydrazine
or a hydrocarbon-substituted hydrazine to form the carbonyl-
polyamino group. The hydrazines may be used in the form
of a hydrate, hydrohalide, sulfate, hydrosulfate, etc.
The reaction with hydrazine or a hydrocarbon-substituted
hydrazine proceeds suitably at temperatures ranging from
about 80 to 300C. The reaction temperatures may range
from about 80C. to 350C. or higher provided that said
te~.perature is maintained below the decomposition point
of either the reactants or the products obtained thereof.
-22-
.
,
7 ~ 7~
Thus, for example, at least about 50 mole percent,
e.g., 50-98 mole percent, of the carboxyl groups of a
styrenemaleic interpolymer may be e~terified with a high
molecular weight aliphatic alcohol and then subsequently
reacted with hydra~ine, etc., to obtain a nitrogen-containing
ester having about 2.0 to 50 or 2.0 to 35 molar percent
of the carboxylic yroups converted to carbonyl-polyamino
groups. The alcohol-esterified interpolymer is preferably
reacted with hydrazine or a hydrocarbon-substituted hydrazine
to substantially neutralize all of the unesterified carboxy
radicals of the interpolymer. The reaction with hydrazine
is preferably carried out at temperatures ranging from
about 100-350~C. In mcst instances, however, the neutralization
reaction takes place at temperatures ranging from about
150-250C. in the presence of an excess of the hydrazine.
A stoichiometric excess is particularly useful where
it is desirable to neutralize substantially all of the
unesterified carboxy radicals present in the carboxy
interpolymer.
Suitable nitrogen-containing esters of carboxy
interpolymers are disclosed in U.S. patents 3~702,300;
3,956,149 and 3,959,159.
The compositions of the present in~ention preferably
contain a~out ~.1 to about 12% by weight (based on the
total composition) of at least one of the above-described
interpolymers, more preferably, about 3~ to about 10
by weight of the total composition. Prefe~ably, the
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27;~
amount by weight of such polymers in the compositions
of this invention is at least equal to the amount of
solid particles, e.g., graphite, molybdenum disulfide
and the like, present. More preferably, the amount of
S interpolymer is at least about 2 times, still more preferably
at least about 3 times, the amount of solid particles.
The compositions of the present invention possess
the advantageous combination of a high degree of effectiveness
with respect to lubricity, dispersant-detergent properties,
pour-point depressing action and viscosity index improvements.
Further, the present compositions provide for improved
fuel economy and reduced tendency to form deposits.
In addition to the components already described
herein, lubricating compositions contemplated herein
can contain conventional adjuvants, such as, for example,
anti-oxidants, metal deactivators, pour point depressants,
oiliness agents, blooming agents, peptizing agents, and
the like.
; The lubricating compositions of the present invention
may be prepared in any conventional manner. For example,
the various components may be brought together and blended
at a slightly elevated temperature, i.e., about 100 to
130F., to insure a uniform composition.
In many instances, the additives incorporated into
the present lubricating compositions are available as
a mixture in a mineral oil or other solvent carrier.
Unless otherwise noted, the weight proportions given above
refer to the amount of additive material on a ~arrier
or solvent free basis.
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72
The lubricating compositions of the present invention
can be used to lubricate internal combustion engines.
Maintaining ~or causing to be maintained) a lubricating
amount of the lubricating compositions of the present
invention on the components of such internal combustion
engine requiring lubrication, results in obtaining substantial
benefits from the present invention~
The following examples illustrate clearly the present
invention. However, these examples are not to be interpreted
as specific limitations on the invention.
EXAMPLES 1 - 4
The following examples illustrate certain of the
outstanding benefits of the present invention.
A series of four lubricating oil compositions were
prepared by blending together individual components, noted
below, at a slightly elevated temperature, i.e., about
100F. to about 130F., to insure proper mixing. The
final compositions were as follows:
Example
Component, Wt.~ 1 ? _ 3_ 4
Mineral Oil, 125 SUS
at 100F. 84.074.7 74.274.2
Conventional Additive
Mixture(l) 7.4 7.5 7.5 7.5
Methacrylate Polymer(2) 8.6 7.8
Nitrogen-containing interpolymer(3) - - 8.3
Nitrogen-containing interpolymer(4) - - - 8.3
Graphite Dispersion(5) - 10.0 10.010.0
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,
~72'7:~
(1) This mixture is a commercially available combina-
tion of materials each of which is conventionally -~
used in lubricating oil compositions. This mixture
incluaes alkyl zinc dithiophosphate, both overbased
and neutral calcium sulfonates, calcium phosphonate-
phenate and both an ashless dispersant and an ashless
rust inhibitor. This mixture also included about
50% by weight of a light mineral oil as solvent for
the active ingredients.
(2) A commercially available methacrylate polymer
known and conventionally used to improve the viscosity
index of lubricating oil polymers. Such polymer includes
essentially no N-vinyl pyrrolidone. The material
as used includes about 50% by weight of a mineral
oil as solvent for the polymer. The polymer is believed
to have an average molecular weight of about 800,000
and to be derived from a methacrylic ester containing
about 16 carbon atoms per molecule.
` (3) A styrene maleic interpolymer is obtained by
preparing a solution of styrene (16.3 parts by weight)
and maleic anhydride (12.9 parts) in a benzene-toluene
solution (270 parts; weight ratio of benzene:toulene
being 66.5:33.5) and contacting the solution at 86C.
in nitrogen atmosphere for 8 hours with a catalyst
solution prepared by dissolving 70~ benzoyl peroxide
(0.42) part in a similar benzene-toulene ~ixture
(2.7 parts). The resulting product is a thick slurry
of the interpolymer in the solvent mixture. A mineral
oil (141 parts) is added to the slurry while the
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7'X77~
solvent mixture is being distilled off at 150C.
and then at 150C./200 mm. Hg~ To 209 parts of the
stripped mineral oil-interpolymer slurry (the interpolymer
having a reduced specific viscosity of 0.72) there
are added toluene (25.2 parts), n-butyl alcohol (4.8
parts~, a commercial alcohol consisting essentially
of primary alcohols having from 12 to 18 carbon atoms
(55.6 parts) and a commercial alcohol consisting
of primary alcohols having from 8 to 10 carbon atoms
(10 parts) and to the resulting mixture there is
added 96% sulfuric acid (2.3 parts). The mixture
is then heated at 150-160C. for 20 hours whereupon
water is distilled off. An additional amount of
sulfuric acid (0.18 part) together with an additional
amount of n-butyl alcohol (3 parts) is added and
the esterification is continued until 95% of the
carboxy radicals of the polymer has been esterified.
To the esterified interpolymer, there is then added
aminopropyl morpholine (3.71 parts; 10% in excess
of the stoichiometric amount required to neutralize
the remaining free carboxy radicals) and the resulting
mixture is heated to 150-160C./10 mm. Hg to distill
off toluene and any other volatile components. The
stripped product is mixed with an additional amount
of mineral oil (12 parts) and filtered. The filtrate
is a mineral oil solution of the nitrogen-containing
mixed ester having a nitrogen content of 0.16-0.17%.
(4) A carboxy interpolymer is obtained by preparing
Z
a solution of styrene (16.3 parts by weight) and
maleic anhydride (12.9 parts by weight) in a benzene-
toluene solution (270 parts; weight ratio of benzene
to toluene being 66.5 to 33.5) and contacting the
solution at 86C~ in nitrogen atmosphere for 8 hours
with a catalyst solution prepared by dissolving 70%
benzoyl peroxide (0.42 part by weight) in sjmilar
benzene-toluene mixture (2.7 parts by weight. The
resulting product is a thick slurry of the interpolymer
in the solvent mixture. To the slurry there is added
mineral oil (141 parts by weight) while the solvent
mixture is being distilled off at 150C. and then
at 150C./200 mm Hg. To 209 parts by weight of the
stripped mineral oil-interpolymer slurry (the interpolymer
having a reduced specific viscosity of 0.72) there
are added toluene (25.2 parts by weight), n-butyl
alcohol (4.8 parts by weight), a commercial alcohol
consisting essentially of primary alcohols having
from 12 to 18 carbon atoms (56.6 parts by weight)
and a commercial alcohol consisting of primary alcohols
having from 8 to 10 carbon atoms (10 parts by weight)
and to the resulting mixture there is added 96% sulfuric
acid (2.3 parts by weight). The mixture is then
heated at 150-160C. for 20 hours whereupon water
is distilled off. An additional amount of sulfuric
acid (0.18 part by weight) together with an additional
amount of n-butyl alcohol (3.0 parts by weight) is
added and the esterification is continued until 95~
of the carboxy radicals of the polymer has been esterified.
To the esterified interpolymer (400 parts by weight),
there is then added hydrazine (64~ aqueous solution~(2.7
paLt~ by weight) and the resu'l r~ m_~t~rs is
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~ '
11~72~
heated to 150C. and then to 150C/100 mm Hg. to
distill off volatile components. The stripped product
is mixed with mineral oil (126 parts by weight)
and filtered. The filtrate is a mineral oil solution
of the nitrogen-containing ester.
(5) A mineral oil-based dispersion containing about
1~ by weight of solid graphite particles which have
an average (by weight) particle size of about 200
millimicrons. The dispersion also includes about
6% of a nitrogen and methacrylate-containing dispersant
to aid in maintaining dispersion stability. This
dispersant is believed to be derived from a methacrylic
ester containing about 16 carbon atoms per molecule.
.
Each of these lubricating oil compositions identified
in Examples 1 and 2 was used to lubricate an internal
combustion engine which, in turn, was operated through
a Reference Sequence V C Test. This test, in which the
engine is operated for 192 hours, is described in "Multicylinder
Test Sequences for Evaluating Automotive Engine Oils--
ASTM Special Technical Publication 315F", American Society
; for Testing and Materials (1973). This procedure is known
to produce data which can be used to make valid comparisons
of the effects various lubricating oil compositions have
on engine sludge and varnish ratings under normal operating
conditions.
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~1~7272
Sludge and varnish ratings in the Referance Sequence
V C Test are based upon visual inspection of various engine
components and comparison with a series of CRC reference
standards.
Results of this test using each of the above-described
lubricating compositions are summarized below. For comparison
purposes, miminum SE standard lubricating oil qualification
ratings are also presented.
COMPOSITION
REFERENCE
SEQUENCE VC
RESULTS 1 _ 2SE MINIMUM RATIN~S
Average Overall 8.7 8.1 8.5
Sludge Rating
Average Overall 8.3 7.8 8.0
Varnish Rating
Piston Skirt 8.3 8.0 7.9
The above data indicate that compositions which include
solid particles cause a substantial decrease in sludge
and varnish ratings (increase in sludge and varnish formation).
This conclusion is apparent by comparing the results from
Composition 2 with those from the non-graphite containing
Composition 1. Thus, the inclusion of the conventional
viscosity index improver, which provides adequate sludge
and varnish formation protection (see Example 1) when in-
cluded in a composition without solid particles, fails
to meet the SE qualification standards when such solid
particles are added.
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1~07272
The Sequence V C Test described in Examples l and 2
illustrate the problems in formulating a suitable solids
particles-containing lubricating composition. Examples
3 and 4 are lubricating oil composition in accordance
with the invention. These lubricating compositions con-
taining graphite and nitrogen containing esters of carboxy-
containing interpolymers of the invention provide reduced
sludge and varnish deposition relative to lubricating
compositions not containing these interpolymers, and are
illustrative of the improved solids containing lubricating
compositions of the invention.
While this invention has been described with respect
to various specific examples and embodiments, it is to
be understood that the invention is not limited thereto
and that it can be variously practiced within the scope
of the following claims.
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