Note: Descriptions are shown in the official language in which they were submitted.
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POLYALKYLENE SUCCINIMIDE COMPOSITION
USEFUL IN INTERNAL COMBUSTION ENGINES
The present invention relates to novel compositions comprising mixtures of
post-treated derivatives of polyalkylene succinimides. In a further aspect,
the
invention relates to methods of preparing these compositions and their uses as
dispersants in lubricating oils. In another aspect, the invention relates to
concentrates and lubricating oil compositions.
BACKGROUND OF THE INVENTION
Lubricating oil compositions for internal combustion engines generally contain
a variety of additives to reduce or control deposits, wear, corrosion, etc.
The
present invention is concerned with compositions useful as dispersants in
lubricating oil compositions.
In lubricating oils, dispersants function to control sludge, carbon, and
varnish
produced primarily by the incomplete combustion of the fuel, or impurities in
the fuel, or impurities in the base oil used in the lubricating oil
composition.
Dtspersants also control viscosity increase due to the presence of soot in
diesel engine lubricating oils.
One of the most effective classes of lubricating oil dispersants is
polyalkylene
succinimides. In some cases, the succinimides have also been found to
provide fluid-modifying properties, or a so-called viscosity index credit, in
lubricating oil compositions. That produces a reduction in the amount of
viscosity index improver which would be otherwise have to be used.
Polyalkylene succinimides are generally prepared by the reaction of the
corresponding polyalkylene succinic anhydride with a polyalkyl polyamine.
Polyalkylene succinic anhydrides are generally prepared by a number of well-
known processes. For example, there is a well-known thermal process (see,
e.g., U.S. Patent No. 3,361,673), an equally well-known chtorination process
(see, e.g., U.S. Patent No. 3,172,892), a combination of the thermal and
chlorination processes (see, e.g., U.S. Patent No. 3,912,764), and free
radical
processes (see, e.g., U.S. Patent Nos. 5,286,799 and 5,319,030). Such
compositions include one-to-one monomeric adducts (see, e.g., U.S. Patent
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Nos. 3,219,666 and 3,381,022), as well as "multiply adducted" products,
adducts having alkenyl-derived substituents adducted with at least 1.3
succinic
groups per alkenyl-derived substituent (see, e.g., U.S. Patent No. 4,234,435).
U.S. Patent Nos. 3,361,673 and 3,018,250 describe the reaction of an alkenyl-
or alkyl-substituted succinic anhydride with a polyamine to form alkenyl or
alkyl
succinimide lubricating oil dispersants and/or detergent additives.
U.S. Patent No. 4,612,132 teaches that alkenyl or alkyl succinimides may be
modified by reaction with a cyclic or linear carbonate or chloroformate such
that
one or more of the nitrogens of the polyamine moiety is substituted with a
hydrocarbyl oxycarbonyl, a hydroxyhydrocarbyl oxycarbonyl, or a hydroxy
poly(oxyalkylene) oxycarbonyl. These modified succinimides are described as
exhibiting improved dispersancy and/or detergency in lubricating oils.
U.S. Patent No. 4,747,965 discloses modified succinimides similar to those
disclosed in U.S. Patent No. 4,612,132, except that the modified succinimides
are described as being derived from succinimides having an average of greater
than 1.0 succinic groups per long chain alkenyl substituent.
An article by S. T. Roby, R. E. Kornbrekke, and J. A. Supp "Deposit
Formulation in Gasoline Engines, Part 2, Dispersant Effects on Sequence VE
D2pOSItS"JOURNAL OF THE SOCIETY OF TRIBOLOGISTS AND LUBRICATION
2O ENGINEERS, Vol. 50, 12, 989-995 (December 1994) teaches that the length of
the dispersant alkyl side chain influences deposit control performance, and
that, at the same nitrogen level, the low molecular weight (side chain 1,000
daltons) dispersants that were tested were poorer in controlling deposits than
the tested high molecular weight (side chain 2,000 daltons) succinimide
dispersants. This teaching is also consistent with the prior observation
comparing 950 Mn side chain succinimides with 2,200 Mn side chain
succinimides.
U.S. Patent No. 4,234,435 teaches a preferred polyalkene-derived substituent
group with a Mn in the range of 1,500 to 3,200. For polybutenes, an especially
preferred Mn range is 1,700 to 2,400.
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A variety of post-treatments for improving various properties of alkenyl
succinimides are known to the art, a number of which are described in U.S.
Patent No. 5,241,003.
Example 2 of U.S. Patent No. 5,266,186 discloses the preparation of
dispersants by reacting certain polyisobutenyl-succinic anhydride adducts (see
footnote 2 of Table 2) with ethylenediamine, followed by reaction with a
malefic
anhydride/alpha-olefin copolymer. The patent teaches that, by functioning as
an iron sulfide dispersant, the product is useful to inhibit sludge deposits
in
refinery processing equipment caused by the heat treatment of hydrocarbon
feed stocks.
U.S. Patent No. 5,112,507 discloses a polymeric ladder type polymeric
succinimide dispersant in which each side of the ladder is a long chain alkyl
or
alkenyl, generally having at least about 30 carbon atoms, preferably at least
about 50 carbon atoms. The dispersant is described as having improved
hydrolytic stability and shear stress stability, produced by the reaction of
certain
malefic anhydride-olefin copolymers with certain polyamines. The patent
further
teaches that the polymer may be post-treated with a variety of post-
treatments,
and describes procedures for post-treating the polymer with cyclic carbonates,
linear mono- or polycarbonates; boron compounds (e.g., boric acid), and
fluorophosphoric acid and ammonia salts thereof.
U.S. Patent Nos. 5,334,321 and 5,356,552 disclose certain cyclic carbonate
post-treated alkenyl or alkylsuccinimides having improved fluorocarbon
elastomer compatibility, which are preferably prepared by the reaction of the
corresponding substituted succinic anhydride with a polyamine having at least
four nitrogen atoms per mole. Both of these patents disclose the possibility
of
borating certain cyclic carbonate post-treated alkenyl or alkylsuccinimides.
U.S. Patent Nos. 5,334,321 discloses that higher molecular weight alkenyl or
alkylsuccinimides give better detergency than the corresponding lower
molecular weight alkenyl or alkyfsuccinimides.
Mixtures of borated and carbonated polyalkylene succinimides have been
derived from the same molecular weight polyalkylenes. The mixtures show
inferior soot dispersancy to the individual borated and carbonated
polyalkylene
succinimides used alone.
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U.S. Patent No. 5,716,912 discloses polyalkylene succinimides prepared by
reacting, under reactive conditions, a mixture of a polybutene succinic acid
derivative, an unsaturated acidic reagent copolymer of an unsaturated acidic
reagent and an olefin, and a polyamine, then treating those succinimides with
cyclic carbonates, linear mono- or polycarbonates, or a boron compound.
SUMMARY Oi= THE INVENTION
The present invention provides a lubricating oil composition with improved
detergency.
In one embodiment, the lubricating oil composition of the present invention
comprises:
(a) a major amount of a base oil of lubricating viscosity;
(b) from 0.5% to 15% of a carbonate-treated polyalkylene succinimide
additive prepared by treating a first polyalkylene succinimide with a
cyclic carbonate or a linear mono- or poly-carbonate under reactive
conditions;
(c) from 0.5% to 15% of a borated polyalkylene succinimide additive
prepared by treating a second polyalkylene succinimide with a boron
compound under reactive conditions;
(d) from 0.5% to 20% of a metal-containing detergent; and
(e) from 0.1 % to 3% of a zinc dialkyldithiophosphate.
Preferably, the number average molecular weight of the polyalkylenes from
which the carbonate-treated polyalkylene succinimide additive is derived is at
least 300 greater than the number average molecular weight of the
polyalkylenes from which the boron-treated polyalkylene succinimide additive
is
derived.
The lubricating oil composition preferably further contains from 0.02% to 5%
of
a molybdenum compound. The content of the molybdenum compound in the
lubricating oil composition preferably is in an amount of 10 to 2,500 ppm in
terms of molybdenum element.
The lubricating oil composition preferably further contains at least one of
the
following: from 1 % to 20% of a viscosity index improver and from 0.1 % to 5%
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of an oxidation inhibitor selected from the group consisting of phenol
compounds and amine compounds.
Preferably, the carbonate-treated polyalkylene succinimide additive is a
reaction product of a high molecular weight alkenyl- or alkyl-substituted
succinic anhydride and a polyaikylene polyamine having an average of 4 to 10
nitrogen atoms per mole and is post-treated with a cyclic carbonate.
Preferably, the polyalkylene group of the carbonate-treated polyalkylene
succinimide additive is derived from a polybutene having a molecular weight of
from 1,000 to 2,700, more preferably from 1,900 to 2,700.
Preferably, the polyalkylene group of the borated polyalkylene succinimide
additive is derived from a polybutene having a molecular weight of from 1,000
to 2,700.
Preferably, the carbonate-treated polyalkylene succinimide additive and the
borated polyalkylene succinimide additive are contained in a total amount of
1 % to 15%, and the carbonate-treated polyalkylene succinimide additive and
the borated polyalkylene succinimide additive are contained in a weight ratio
of
2:8 to 8:2.
In a further aspect, the present invention also provides a polyalkylene
succinimide composition that improves the soot dispersancy properties of a
lubricating oil composition. This polyalkylene succinimide composition
comprises borated and carbonated polyalkylene succinimides derived from
different molecular weight polyalkylenes.
The polyalkylene succinimide composition comprises from 10% to 50% of a
boron-treated polyalkylene succinimide and from 50% to 90% of a carbonate-
treated polyalkylene succinimide. This polyalkylene succinimide composition
produces superior soot dispersancy to either the boron-treated polyalkylene
succinimide or the carbonate-treated polyalkylene succinimide when
used alone.
The boron-treated polyalkylene succinimide is derived from polyalkylenes
having a lower molecular weight than the polyalkylenes from which the
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carbonate-treated polyalkylene succinimide is derived. This difference in
molecular weight is at least 300, preferably from 800 to 1,000.
Preferably, the boron-treated polyalkylene succinimide is a polybutene
succinimide derived from pofybutenes having a molecular weight of from 1,200
to 1,400 and the carbonate-treated polyalkylene succinimide is a polybutene
succinimide derived from polybutenes having a molecular weight of from 2,000
to 2,400. Preferably, the carbonate-treated polybutene succinimide is prepared
by reacting, under reactive conditions, a mixture of a polybutene succinic
acid
derivative, an unsaturated acidic reagent copolymer of an unsaturated acidic
reagent and an olefin, and a polyamine.
The soot dispersancy of a lubricating oil in internal combustion engine
applications can be improved by adding to that lubricating oil an effective
amount of the polyalkylene succinimide composition of the present invention.
The invention provides a lubricating oil composition comprises a major amount
of a base oil of lubricating viscosity and the polyalkylene succinimide
composition of the present invention.
The invention also provides a concentrate comprising the polyalkylene
succinimide composition of the present invention, an organic diluent, and
preferably at least one other additive. The organic diluent constitutes from 1
to 20% of the concentrate, and the polyalkylene succinimide composition
constitutes from 5% to 80% of the concentrate.
DETAILED DESCRIPTION OF THE INVENTION
The present invention involves a lubricating oil composition comprising a
major
portion of a base oil, specific amounts of a cyclic carbonate-treated
polyalkylene succinimide additive, a borated polyalkylene succinimide
additive,
a metal-containing detergent, and a zinc dialkyldithiophosphate. In a further
aspect, the present invention involves a polyalkylene succinimide composition
that comprises a mixture of borated and carbonated polyalkylene succinimides
derived from different number average molecular weight polyalkylenes.
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DEFINITIONS
As used herein the following terms have the following meanings unless
expressly stated to the contrary:
The term "succinimide" is understood in the art to include many of the amide,
imide, etc. species that are also formed by the reaction of a succinic
anhydride
with an amine. The predominant product, however, is succinimide and this term
has been generally accepted as meaning the product of a reaction of an
alkenyl- or alkyl-substituted succinic acid or anhydride with a polyamine.
Polyalkyfene succinimides are disclosed in numerous references and are well
known in the art. Certain fundamental types of succinimides and related
materials encompassed by the term of art "succinimide" are taught in U.S.
Patent Nos. 2,992,708; 3,018,291; 3,024,237; 3,100,673; 3,219,666;
3,172,892; and 3,272,746, the disclosures of which are hereby incorporated by
reference in their entirety for all purposes.
The term "polyalkylene succinic acid derivative" refers to a structure having
the
formula:
O
R-CH-C
L
M
CHZ C
O
wherein R is a polyalkylene, and L and M are independently selected from the
group consisting of -OH, -CI, -O-, lower alkyl or taken together are -O- to
form a
polyalkylene succinic anhydride group.
The term "unsaturated acidic reagent" refers to malefic or fumaric reactants
of
the general formula:
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O O
C - CH =CH C
wherein X and X' are the same or different, provided that at least one of X
and
X' is a group that is capable of reacting to esterify alcohols, form amides,
or
amine salts with ammonia or amines, form metal salts with reactive metals or
basically reacting metal compounds, and otherwise function as acylating
agents. Typically, X and/or X' is -OH, -O-hydrocarbyl, -OM+ where M+
represents one equivalent of a metal, ammonium or amine cation, -NH2, -CI,
-Br, and taken together X and X' can be -O- so as to form an anhydride.
Preferably, X and X' are such that both carboxylic functions can enter into
acylation reactions. Malefic anhydride is a preferred unsaturated acidic
reactant. Other suitable unsaturated acidic reactants include electron-
deficient
olefins such as monophenyi malefic anhydride; monomethyl, dimethyl,
monochloro, monobromo, monofluoro, dichloro and difluoro malefic anhydride;
N-phenyl maleimide and other substituted maleimides; isomaleimides; fumaric
acid, malefic acid, alkyl hydrogen maleates and fumarates, dialkyl fumarates
and maleates, fumaronilic acids and maleanic acids; and maleonitrile, and
fumaronitrile.
Unless otherwise specified, all molecular weights are number average
molecular weights (Mn).
Unless otherwise specified, all percentages are in weight percent and are
based on the amount of active and inactive components, including any process
oil or diluent oil used to form that component.
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BASE OIL OF LUBRICATING VISCOSITY
The base oil of lubricating viscosity used in such compositions may be mineral
oils or synthetic oils of viscosity suitable for use in the crankcase of an
internal
combustion engine. The base oil preferably has a dynamic viscosity of 2 to 50
mm2/s at 100°C and may be derived from synthetic or natural sources.
Mineral
oils for use as the base oil in this invention include paraffinic, naphthenic,
and
other oils that are ordinarily used in lubricating oil compositions. Synthetic
oils
include both hydrocarbon synthetic oils and synthetic esters. Useful synthetic
hydrocarbon oils include liquid polymers of alpha olefins having the proper
viscosity. Especially useful are the hydrogenated liquid oligomers of C6 to
C~2
alpha olefins such as 1-decene trimer. Likewise, alkyl benzenes of proper
viscosity, such as didodecyl benzene, can be used. Useful synthetic esters
include the esters of monocarboxylic acids and polycarboxylic acids, as well
as
monohydroxy alkanols and polyols. Typical examples are didodecyl adipate,
pentaerythritol tetracaproate, di-2-ethylhexyl adipate, dilaurylsebacate, and
the
like. Complex esters prepared from mixtures of mono- and dicarboxylic acids
and mono- and dihydroxy alkanols can also be used. Blends of mineral oils
with synthetic oils are also useful.
POLYALKYLENE SUCCIN1MIDE
The polyalkylene succinimides of the lubricating oii composition of the
present
invention comprises from 0.5% to 15% of a carbonate-treated polyalkylene
succinimide derived from a higher molecular weight polyafkylene and from
0.5% to 15% of a boron-treated polyalkylene succinimide derived from a lower
molecular weight polyalkylene. The combination of the two succinimides
produces superior detergency and soot dispersancy to either the boron-treated
polyalkylene succinimide or the carbonate-treated polyalkylene succinimide
when used alone. The advantages of the boron-treated polyalkylene
succinimide in TBN contribution and prevention of bearing corrosion are also
preserved.
The individual polyalkylene succinimides of the present invention can be
prepared by conventional processes, such as disclosed in U.S. Patent No.
2,992,708; 3,018,250; 3,018,291; 3,024,237; 3,100,673; 3,172,892; 3,219,666;
3,272,746; 3,361,673; 3,381,022; 3,912,764; 4,234,435; 4,612,132; 4,747,965;
5,112,507; 5,241,003; 5,266,186; 5,286,799; 5,319,030; 5,334,321; 5,356,552;
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5,716,912, the disclosures of which are all hereby incorporated by reference
in
their entirety for all purposes.
Carbonate-Treated Polyalkylene Succinimide
The cyclic carbonate-treated polyalkylene succinimide additive is an ashless
dispersant and can be prepared by reaction of a high molecular weight alkenyl-
or alkyl-substituted succinic anhydride and a polyalkylene pofyamine having an
average of 4 to 10 nitrogen atoms (preferably 5 to 7 nitrogen atoms) per mole
and is post-treated with a cyclic carbonate. The polyalkylene of the cyclic
carbonate-treated polyalkylene succinimide additive is derived from
polyalkylenes having a molecular weight of at least 1,000. Preferably, the
carbonate-treated polyalkylene succinimide is a polybutene succinimide
derived from polybutenes having a molecular weight of from 1,000 to 2,700,
more preferably 1,900 to 2,700, and most preferably 2,000 to 2,400.
The polyalkylene of the cyclic carbonate-treated polyalkylene succinimide
additive is prepared by reacting, under reactive conditions, a mixture of a
polybutene succinic acid derivative, an unsaturated acidic reagent copolymer
of an unsaturated acidic reagent and an olefin, and a polyamine, such as
taught in U.S. Patent No. 5,716,912.
Boron-Treated Polyalkylene Succinimide
The borated polyalkylene succinimide additive is an ashless dispersant and
can be prepared by reaction of a high molecular weight alkenyl- or alkyl-
substituted succinic anhydride and a polyalkylene polyamine having an
average of 4 to 10 nitrogen atoms (preferably 5 to 7 nitrogen atoms) per mole
and is post-treated with a boric acid or boric acid compound. The polyalkylene
of the boron-treated polyalkylene succinimide additive is derived from
polyalkylenes having a molecular weight of at least 1,000. Preferably, the
boron-treated polyalkylene succinimide is derived from polybutenes having a
molecular weight of from 1,000 to 2,700, more preferably 1,200 to 1,400, most
preferably about 1,300. The boron content in the borated polyalkylene
succinimide additive preferably is in the range of 0.1 % to 5%, more
preferably
0.2% to 2%.
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In the lubricating oil composition of the invention, the cyclic carbonate-
treated
polyalkylene succinimide additive and the borated polyalkylene succinimide
additive are preferably contained in a weight ratio of 2:8 to 8:2. The cyclic
carbonate-treated polyalkylene succinimide additive and the borated
polyalkylene succinimide additive are preferably contained in the lubricating
oil
composition in a total amount of from 1 % to 15%.
The lubricating oil composition of the invention can further contain other
ashless dispersants such as other succinic imide dispersants, succinic acid
ester dispersants, and benzylamine dispersants.
POLYALKYLENE SUCCINIMIDE COMPOSITION
The polyalkylene succinimide composition of the present invention comprises
from 10% to 50% of a boron-treated polyalkylene succinimide derived from a
lower molecular weight polyalkylene and from 50% to 90% of a carbonate-
treated polyalkylene succinimide derived from a higher molecular weight
polyalkylene. Preferably, the polyalkylene succinimide composition of the
present invention comprises from 20% to 40% of the boron-treated
polyalkylene succinimide and from 60% to 80% of the carbonate-treated
polyalkylene succinimide. This polyalkylene succinimide composition produces
superior soot dispersancy to either the boron-treated polyalkylene succinimide
or the carbonate-treated polyalkylene succinimide when used alone. The
advantages of the boron-treated polyalkylene succinimide in TBN contribution
and prevention of bearing corrosion are also preserved.
The individual polyalkylene succinimides used in the polyalkylene succinimide
composition of the present invention can be prepared by conventional
processes, such as disclosed in U.S. Patent No. 2,992,708; 3,018,250;
3,018,291; 3,024,237; 3,100,673; 3,172,892; 3,219,666; 3,272,746; 3,361,673;
3,381,022; 3,912,764; 4,234,435; 4,612,132; 4,747,965; 5,112,507; 5,241,003;
5,266,186; 5,286,799; 5,319,030; 5,334,321; 5,356,552; 5,716,912, the
disclosures of which are all hereby incorporated by reference in their
entirety
for all purposes.
The polyalkylene succinimide composition can be prepared by physically
mixing the boron-treated polyalkylene succinimide and the carbonate-treated
polyalkylene succinimide. The polyalkylene succinimide composition might
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have a slightly different composition than the initial mixture, because the
components may interact.
METAL DETERGENT
The lubricating oil composition of the invention further contains from 0.5% to
20% of a metal-containing detergent. Representatives of the metal-containing
detergents are metal phenates and metal sulfonates.
The metal phenate is an alkali metal salt or an alkaline earth metal salt of a
sulfide of an alkylphenol having an alkyl group of approximately 8 to 30
carbon
atoms. The metal sulfonate is an alkali metal salt or an alkaline earth metal
salt
of a sulfonate of a mineral oil having a molecular weight of approximately 400
to 6,000 or an aromatic compound having an alkyl group. Examples of the
alkali metal salts and alkaline earth metal salts also include lithium salts,
sodium salts, calcium salts, magnesium salts, and barium salts. The metal
phenate and the metal sulfonate can be employed singly or in combination.
Other metal-containing detergents such as an alkaline earth metal salicylate,
an alkaline earth metal phosphonate, and an alkaline earth metal naphthenate
can be employed in combination with the metal phenate and/or the metal
sulfonate.
The metal-containing detergent can be a neutral type or an overbased type
having a total base number (TBN) of 150 to 300, or more.
ZINC DIALKYLDITHIOPHOSPHATE
The lubricating oil composition of the invention further contains from 0.1 %
to
3% of a zinc dialkyldithiophosphate (i.e., ZnDTP). The zinc
dialkyldithiophosphate preferably is zinc dialkyldithiophosphate containing an
alkyl group of 3 to 18 carbon atoms. Preferably the alkyl group of the zinc
dialkyldithiophosphate is derived from a secondary alcohol of 3 to 18 carbon
atoms or a mixture of the secondary alcohol and a primary alcohol.
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OTHER ADDITIVE COMPONENTS
The following additive components are examples of other components that can
be favorably employed in the present invention. These examples of additives
are provided to illustrate the present invention, but they are not intended to
limit
it:
(1 ) Oxidation inhibitors
The lubricating oil composition preferably may contain an oxidation
inhibitor in an amount of 0.02% to 5%, more preferably 0.1 % to 3%.
(a) Phenol type oxidation inhibitors: 4,4'-methylene bis
(2,6-di-tert-butylphenol), 4,4'-bis(2,6-di-tert-butylphenol),
4,4'-bis(2-methyl-6-tert-butylphenol), 2,2'-methylene bis
(4-methyl-6-tert-butylphenol), 4,4'-butylene bis(3-methyl-6-tert-
butylphenol), 4,4'-isopropylene bis(2,6-di-tert-butylphenol),
2,2'-methylene bis(4-methyl-6-nonylphenol), 2,2'-isobutylene
bis(4,6-dimethylphenol), 2,2'-methylene bis (4-methyl-
6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol,
2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol,
2,6-di-tert-1-dimethylamino-p-cresol, 2,6-di-tert-4-(N.N'
dimethylaminomethylphenol), 4,4'-thiobis(2-methyl-6-tert-
butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), and
bis(3-methyl-4-hydroxy-5-tert-butylbenzyl)-sulfide.
(b) biphenyl amine type oxidation inhibitor: alkylated diphenyl
amine, phenyl-a-naphthylamine, and alkyfated-
a-naphthylamine.
(c) Other types: metal dithiocarbamate (e.g., zinc
dithiocarbamate) and methylene bis(dibutyldithiocarbamate).
(2) Rust inhibitors (Anti-rust agents)
(a) Nonionic polyoxyethylene surface active agents:
polyoxyethylene lauryl ether, polyoxyethylene higher alcohol
ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene
octyl phenyl ether, polyoxyethylene octyi stearyl ether,
polyoxyethylene oleyl ether, polyoxyethylene sorbitol
monostearate, polyoxyethylene sorbitol mono-oleate, and
polyethylene glycol monooleate.
(b) Other compounds: stearic acid and other fatty acids,
dicarboxilic acids, metal soaps, fatty acid amine salts, metal
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salts of heavy sulfonic acid, partial carboxylic acid ester of
polyhydric alcohol, and phosphoric ester.
(3) Demulsifiers: addition product of alkylphenol and ethylene oxide,
polyoxyethylene alkyl ether, and polyoxyethylene sorbitan ester.
(4) Friction modifiers: fatty alcohol, fatty acid, amine, borated ester,
and other esters.
(5) Multifunctional additives: Examples of the molybdenum
compounds include a sulfur-containing oxymolybdenum succinic
imide complex compound (described in Japanese (examined)
Patent Publication No. H3-22438), sulfurized oxymolybdenum
dithiocarbamate, sulfurized oxymolybdenum organo phosphoro
dithioate, oxymolybdenum monoglyceride, oxymolybdenum
diethylate amide, amine-molybdenum complex compound, and
sulfur-containing molybdenym complex compound. The lubricating
oil composition preferably contains a molybdenum compound in an
amount of 0.02% to 5%, more preferably 0.1 to 3%. The content of
the molybdenum compound in the lubricating oil composition
preferably is in an amount of 10 to 2,500 ppm in terms of
molybdenum element.
(6) Viscosity index improvers: polymethacrylate type polymers,
ethylene-propylene copolymers, styrene-isoprene copolymers,
hydrated styrene-isoprene copolymers, polyisobutylene, and
dispersant type viscosity index improvers. The lubricating oil
composition of the invention preferably may contain a viscosity
index improver in an amount of 7 % to 20%.
(7) Pour point depressants: polymethyl methacrylate.
(8) Foam Inhibitors: alkyl methacrylate polymers and dimethyl
silicone polymers.
LUBRICATING OIL COMPOSITION
The lubricating oil composition of the present invention is useful for
imparting
improved detergency properties to an engine lubricating oil composition. Such
a lubricating oil composition comprises a major portion of a base oil, a
cyclic
carbonate-treated polyalkylene succinimide additive, a borated polyalkylene
succinimide additive, a metal-containing detergent, and a zinc
dialkyldithiophosphate.
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A further aspect of the present invention involves a polyalkylene succinimide
composition that comprises a mixture of borated and carbonated polyalkylene
succinimides derived from different number average molecular weight
polyalkylenes.
The polyalkylene succinimide compositions of the present invention are useful
for imparting improved soot dispersancy properties to an engine lubricating
oil
composition. Such a lubricating oil composition comprises a major part of base
oil of lubricating viscosity and an effective amount of the polyalkylene
succinimide composition of the present invention. Adding an effective amount
of the polyalkylene succinimide compositions of the present invention to a
lubricating oil composition improves the soot dispersancy properties of that
lubricating oil composition in automotive applications.
In one embodiment, an engine lubricating oil composition would contain
(a) a major amount of a base oil of lubricating viscosity;
(b) from 0.5% to 15% of a carbonate-treated polyalkylene succinimide
additive prepared by treating a first polyalkylene succinimide with a
cyclic carbonate or a linear mono- or poly-carbonate under reactive
conditions;
(c) from 0.5% to 15% of a borated polyalkylene succinimide additive
prepared by treating a second polyalkylene succinimide with a boron
compound under reactive conditions;
(d) from 0.5% to 20% of a metal-containing detergent; and
(e) from 0.1 % to 3% of a zinc dialkyldithiophosphate.
In a further embodiment, an engine lubricating oil composition is produced by
blending a mixture of the above components. The lubricating oil composition
produced by that method might have a slightly different composition than the
initial mixture, because the components may interact.
The components can be blended in any order and can be blended as
combinations of components. For example, the polyalkylene succinimide
composition can be blended with the other components before, during, and/or
after the boron-treated polyalkylene succinimide and carbonate-treated
polyalkylene succinimide are blended together.
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ADDITIVE CONCENTRATES
Additive concentrates are also included within the scope of this invention.
The
concentrates of this invention comprise an organic diluent and the compounds
or compound mixtures of the present invention, preferably with at least one of
the additives disclosed above. The concentrates contain sufficient organic
difuent to make them easy to handle during shipping and storage.
From 1 % to 20% of the concentrate is organic diluent. From 5% to 80% of
concentrate is the polyalkylene succinimide composition of the present
invention. The remainder of the concentrate may comprise one or more of
other additives discussed above.
These percentages are based on the amount of active and inactive
components, including any process oii or diluent oil used to form that
component. The percent numbers for organic diluent would be greater if only
the active components are considered.
Suitable organic diluents which can be used include for example, solvent
refined 100N, i.e., Cit-Con 100N, and hydrotreated 100N, i.e., Chevron 100N,
and the like. The organic diluent preferably has a viscosity of about from 1
to
cSt at 100°C.
The components of the additive concentrate can be blended in any order and
20 can be blended as combinations of components. For example, the polyalkylene
succinimide composition can be blended with the other components before,
during, and/or after the boron-treated polyalkylene succinimide and carbonate-
treated polyalkylene succinimide are blended together.
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EXAMPLES OF ADDITIVE PACKAGES
Below are representative examples of additive packages that can be used in a
variety of applications. These representative examples employ the novel
dispersants of the present invention. Unlike the percentages used in other
sections of this specification, the following percentages are based on the
amount of active component, with neither process oil nor diluent oil. (All
process oils and diluent oils included are included in the figures for base
oil of
lubricating viscosity.) These examples are provided to illustrate the present
invention, but they are not intended to limit it.
1 ) Polyalkylene succinimide composition 35%
Metal detergent 25%
Primary alkyl zinc dithiophosphate 10%
Base oil of lubricating viscosity 30%
2) Polyalkylene succinimide composition 40%
Metal detergent 20%
Secondary alkyl zinc dithiophosphate 5%
Dithiocarbamate type oxidation inhibitor 5%
Base oil of lubricating viscosity 30%
3) Polyalkylene succinimide composition 35%
Metal detergent 20%
Secondary alkyl zinc dithiophosphate 5%
Phenol type oxidation inhibitor 5%
Base oil of lubricating viscosity 35%
4) Polyalkylene succinimide composition 30%
Metal detergent 20%
Secondary alkyl zinc dithiophosphate 5%
Dithiocarbamate type anti-wear agent 5%
Base oil of lubricating viscosity 40% ,
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5) Polyalkylene succinimide composition 30%
Metal detergent 20%
Secondary alkyl zinc dithiophosphate 5%
Molybdenum-containing anti-wear agent 5%
Base oil of lubricating viscosity 40%
6) Polyalkylene succinimide composition 30%
Metal detergent 20%
Other additives 10%
Primary alkyl zinc dithiophosphate
Secondary alkyl zinc dithiophosphate
Alkylated diphenylamine-type oxidation inhibitor
Dithiocarbamate type anti-wear agent
Base oil of lubricating viscosity 40%
EXAMPLES
The invention will be further illustrated by the following examples, which set
forth particularly advantageous embodiments. While the Examples are
provided to illustrate the present invention, they are not intended to limit
it.
EXAMPLES SHOWING IMPROVED SOOT DISPERSANCY
Four polybutene succinimides were prepared and post-treated by conventional
means. The following percentages are based on the amount of active and
inactive components, including any process oil or diluent oil used to form the
polybutene succinimides.
POLYBUTENE SUCCINIMIDE A
BORATED DISPERSANT
DERIVED FROM 1,300 MN POLYBUTENE
The first polybutene succinimide was derived from 1,300 Mn polybutenes. This
succinimide was formed by reacting a polybutene-substituted succinic acid '
derivative with a heavy polyamine (containing an average of approximately 6.5
nitrogen atoms per mole), then post-treating the resulting polybutene
succinimide with boric acid.
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POLYBUTENE SUCCINIMIDE B
FIRST CARBONATED DISPERSANT
DERIVED FROM 2,200 MN POLYBUTENE
The second polybutene succinimide was derived from 2,200 Mn polybutenes.
This was formed by reacting a polybutene-substituted succinic acid derivative
with a heavy polyamine (containing an average of approximately 6.5 nitrogen
atoms per mole), then post-treating the resulting polybutene succinimide with
ethylene carbonate at a ratio of 2 moles of ethylene carbonate to 1 mole of
basic nitrogen of the pofybutene succinimide.
POLYBUTENE SUCCINIMIDE C
SECOND CARBONATED D1SPERSANT
DERIVED FROM 2,200 MN POLYBUTENE
The third polybutene succinimide was derived from 2,200 Mn polybutenes. This
was formed by reacting a mixture of a polybutene succinic acid derivative, an
unsaturated acidic reagent copolymer of an unsaturated acidic reagent and an
olefin, and a heavy polyamine (containing an average of approximately 6.5
nitrogen atoms per mole), then post-treating the resulting polybutene
succinimide with ethylene carbonate at a ratio of 2 moles of ethylene
carbonate
to 1 mole of basic nitrogen of the polybutene succinimide.
POLYBUTENE SUCCINIMIDE D
CARBONATED DISPERSANT
DERIVED FROM 1,300 MN POLYBUTENE
A comparative carbonated polybutene succinimide was derived from 1,300 Mn
polybutenes. This was formed by reacting a polybutene-substituted succinic
acid derivative with a mixture of 80% heavy polyamine (containing an average
of approximately 6.5 nitrogen atoms per mole) and 20% diethylene triamine,
then post-treating the resulting polybutene succinimide with ethylene
carbonate
at a ratio of 2 moles of ethylene carbonate to 1 mole of basic nitrogen of the
polybutene succinimide.
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RUN SERIES I
Polybutene Succinimides A, B and D were each blended separately into a SAE
15W-40 Screening Formulation (X) containing an effective amount of metallic
detergent, zinc dithiophosphate, and a molybdenum based oxidation inhibitor.
A non-dispersant viscosity index modifier was chosen to eliminate any effects
of viscosity index modifier on the test results.
These compositions were then tested in the ASTM D-5967-96 (Mack T-8)
engine oil test. This test evaluates an oil's ability to control viscosity
increase
due to soot loading in the oil. In general, a lower viscosity increase
indicates
superior performance. This test is a required performance test for the heavy-
duty engine oil performance category, API CG-4. The results are shown in the
table below:
Run 1 2 3 4
Screening Formulation X X X X
Polybutene Succinimide 10%
A
Polybutene Succinimide 8%
B
Polybutene Succinimide 11.5%
B
Polybutene Succinimide 10%
D
Viscosity Increase at 3.8%9.5 cSt 9.25 6.9 cSt 8.3 cSt
soot cSt
Analysis of this data yields a comparison between the various components.
Comparison of the results of Run 1 (borated dispersant from 1,300 Mn
polybutene) versus Run 4 (carbonated dispersant from 1,300 Mn polybutene)
shows the benefit to carbonate treatment in reducing viscosity increase.
Comparison of the two results of the carbonated dispersant from 2,200 Mn
polybutene (Runs 2 and 3) verifies that the test result improves with
increased
treat level. The carbonated dispersant from 2,200 Mn polybutene is superior to
the borated dispersant from 1,300 Mn polybutene, even at a 20% lower
dosage. Because the result of Run 4 (carbonated dispersant from 1,300 Mn
polybutene) was intermediate to Runs 2 and 3 (carbonated dispersant from
2,200 Mn polybutene), no comparison between these polybutene succinimides
is possible from this data.
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RUN SERIES II
Polybutene Succinimides B and C were each blended separately into a Second
Screening Formulation (Y) and tested in the ASTM D-5967-96 test as above,
and the results tabulated below:
Run 5 6
Screening Formulation Y Y
Polybutene Succinimide 8%
B 8%
Polybutene Succinimide
C
Viscosity Increase at 8.81 cSt 4.94 cSt
3.8% soot
Comparison of these results shows Polybutene Succinimide C to be superior to
Polybutene Succinimide B in controlling viscosity increase. Comparing the two
tables, we can infer that Polybutene Succinimide C is also superior to
Polybutene Succinimide A in controlling viscosity increase.
RUN SERIES III
Polybutene Succinimides A and B together (Run 7) and B alone (Run 8) were
blended separately into a Commercial Formulation (Z) and again run in the
ASTM D-5967-96 test as above. As previously discussed in U.S. Patent No.
5,334,321, boration preserves the TBN contribution of the dispersant, so it
was
desired to keep some Polybutene Succinimide A in the final formulation:
Run 7 8
Screening Formulation Z Z
Polybutene Succinimide 3.5%
A 6.5% 10%
Polybutene Succinimide
B
Viscosity Increase at 5.85 cSt 9.5 cSt
3.8% soot
Surprisingly, the mixture of borated succinimide derived from 1,300 Mn
polybutenes and carbonated succinimide derived from 2,200 Mn polybutenes
gave a lower viscosity increase than the carbonated succinimide alone, despite
the fact that the carbonated succinimide has been shown to be superior to
borated succinimide in controlling viscosity increase.
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This Run Series shows the synergy of using a blend of the borated polybutene
succinimide derived from 1,300 Mn polybutenes and the ethylene carbonated
polybutene succinimide derived from 2,200 Mn polybutenes. That blend
provided better soot dispersancy than achieved by using either component
alone.
RUN SERIES IV
Polybutene Succinimides A and C together were blended into the same
Commercial Formulation (Z) as in Run Series III with the following results,
when compared to Run 6 of Run Series II (Formulation Y):
Run 9 6
Screening Formulation Z Y
Polybutene Succinimide 3%
A 5% 8%
Polybutene Succinimide
C
Viscosity Increase at 4.39 cSt 4.94 cSt
3.8% soot
Comparing the results of Runs 9 and 6 shows again that the mixture of borated
1,300 Mn polybutene succinimide and 2,200 Mn carbonated polybutene
succinimide gives superior performance to either dispersant alone. While this
comparison was effected in differing formulations, comparison of the
Polybutene Succinimide B results from Run Series II and III shows that
Formulation Z is more severe in terms of viscosity increase than Formulation
Y.
Only 8% of the Polybutene Succinimide B in Formulation Y gave a lower
viscosity increase than 10% of the same polybutene succinimide in
Formulation Z.
Run Series III and 1V differ in how the ethylene carbonated polybutene
succinimide was formed prior to post-treatment with ethylene carbonate. In
Run Series III, that ethylene carbonated polybutene succinimide was formed by
reacting polybutene-substituted succinic acid with a heavy polyamine. In Run
Series IV, that ethylene carbonated polybutene succinimide was formed by
reacting a mixture of a polybutene succinic acid derivative, an unsaturated
acidic reagent copolymer of an unsaturated acidic reagent and ari olefin, and
a
heavy polyamine. The above tables show that the second type of carbonated
polybutene succinimide provided better soot dispersancy than the first type of
carbonated polybutene succinimide.
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RUN SERIES V
The bearing weight loss of blends of borated polybutene succinimides and
carbonated polybutene succinimides of different molecular weight in a standard
lubricating oil formulation (Z) were compared to the bearing weight loss of
standard lubricating oil formulations having only carbonated polybutene
succinimides. The CRC L-38 test is a standard industry test that measures the
corrosiveness of oil in terms of bearing weight loss. For the API CG-4 oil
performance category, the limit is 43.7 milligrams maximum weight loss. The
results are shown in the table below:
Run 7 10 11 12
Screening Formulation Z Z Z Z
Polybutene Succinimide3.5% 3.5%
A 6.5% 8% 8%
Polybutene Succinimide 6.5%
B
Polybutene Succinimide
C
Bearing Weight Loss 18.5 24 40.5 70.5
Note: As dispersant level increases, the L-38 bearing weight
loss increases, thus a fail at 8% would be expected to be a
more severe fail at 10%.
Run Series V shows the benefit to the mixed dispersant approach in
passivating L-38 bearing weight loss.
RUN SERIES VI
The ASTM D-5967-96 viscosity increase performance of a blend of borated
polybutene succinimides and carbonated polybutene succinimides of the same
molecular weight in a modified formulation (X') was compared to the viscosity
increase performance of only borated or carbonated polybutene succinimides
in Formulation X. The results are shown in the table below:
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Run 13 1 4
Formulation X' X X
Component A 3.5% 10%
Component D 6.5% 10%
Viscosity Increase at 3.8%10.76 9.5 8.3
soot
This comparative example shows that blends of borated polybutene
succinimides and carbonated polybutene succinimides of the same molecular
weights gave worse results than formulations having only borated or
carbonated polybutene succinimides. In this example the Formulation X'
differed from Formulation X in that it contained a second oxidation inhibitor.
This change is not expected to impact the severity of the formulation in terms
of viscosity increase.
EXAMPLES SHOWING IMPROVED DETERGENCY
Lubricating oil compositions of the invention (Run No. 14 to No. 17) and
lubricating oil compositions for comparison (Run No. 18 to No. 21 ) were
prepared according to the formulations set forth as shown below. The
lubricating oil compositions were adjusted to give a 101Af-30 oil (SAE
viscosity
grade) by the addition of viscosity index improver. Additionally, an effective
amount of oxidation inhibitor, zinc dithiophosphate, and a dispersant
viscosity
index improver were added to the lubricating oil composition, including as
other
additives small amounts of anti-rust agent, friction modifier, anti-wear
agent,
metal-deactivating agent, demulsifier, anti-foaming agent, and pour point
depressant. Base oil of 150 neutral oil was used.
POLYBUTENE SUCCINIMIDE E
DISPERSANT DERIVED FROM 900 MN POLYBUTENE
The first polybutene succinimide of this series was derived from 900 Mn
polybutenes. This succinimide (nitrogen content: 1.4%) was formed by reacting
a polybutene-substituted succinic acid derivative with a polyamine.
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POLYBUTENE SUCCINIMIDE F
BORATED DISPERSANT
DERIVED FROM 1,300 MN POLYBUTENE
The second polybutene succinimide of this series (nitrogen content: 1.5 %,
boron content: 0.5%) was prepared using polybutene of a number-average
molecular weight of approximately 1,300 and treating the resulting succinimide
with boric acid, according to Example No. 8 of U.S. Patent No. 5,356,552.
POLYBUTENE SUCCINIMIDE G
CARBONATED DISPERSANT
DERIVED FROM 2,200 MN POLYBUTENE
The third polybutene succinimide of this series (nitrogen content: 0.7%) was
prepared using polybutene of a number-average molecular weight of
approximately 2,200 and treating the resulting succinimide with ethylene
carbonate, according to Example No. 17 of United States Patent 5,356,552.
The test procedures were:
1 ) Hot Tube Test (KES 07-803) for evaluating detergency at high
temperatures.
In a heater block, a glass tube having an inner diameter of 2 mm
is vertically set. The test oil composition and air are introduced into the
glass
tube from its tower end at rates of 0.31 cc/hr. and 10 cc/min., respectively,
at
290°C (temperature of the heater) for 16 hours. Thereafter, the deposit
produced on the glass tube is visually evaluated to mark the lacquer formation
on the basis of 10 points. A higher value means that the lacquer is less and
the detergency is better.
2) Gasoline engine test - Rocker cover sludge test (JASO M331-91) for
evaluating detergency at medium or low temperatures.
A gasoline engine (6-cylindered engine of V-type and 2 L displacement
volume) is operated for 300 hours at a cycle run between low speed run and
high speed run according to the test method defined by Japan Automobile
Standard Organization (JASO M331-91). Thereafter, the sludge deposited on
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the rocker cover was evaluated to mark the amount of deposit on the basis of
points. A higher value means a less amount of deposit.
The results of these test runs are set forth in the following table:
Run
Numbers
Additives 14 15 16 17 18 19 20 21
Polybutene - - - - - - 2.5 2.5
~
Succimide E
Polybutene 1.5 1.5 2.5 2.5 - 4.5 - 2.0
Succimide F
Polybutene ~ 3.0 3.0 2.0 2.0 4.5 - 2.0 -
Succinimide G
Hot Tube Test 6.0 7.5 7.0 8.0 5.0 7.0 5.5 6.5
(10 =
Best)
Rocker Cover 9.3 9.3 9.2 9.2 9.4 8.3 8.2 7.9
Sludge
(10 = Best)
5
sFurther components of the lubricating oil composition:
Calcium phenate sulfide (TBN 250 mg KOH/g): 1.8%.
- Calcium sulfonate (TBN 20 mg KOH/g): 1.7%.
10 - ZnDTP (phosphorus content 7.2% prepared using a secondary
alcohol of 3 to 8 carbon atoms): 1.3%.
- 4,4'-methylenebis (2,6-di-t-butylphenol): 0.5%.
- Alkylated diphenylamine: 0.5%.
- Sulfur-containing oxymolybdenum - succinimide complex compound
75 (Mo content 5.4%): 0.2% for Rules Nos. 15 and 17 only.
- Ethylene-propylene copolymer viscosity index improver: 6.5%.
- Others: 0.4 %.
- 150 Neutral base oil: 82.8%.
The test results set forth in the above table make it clear that the
lubricating oil
compositions containing the combination of the cyclic carbonate-treated
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polyalkylene succinimide additive and the borated polyalkylene succinimide
additive show high detergency at low and medium temperatures (which is
required when the lubricating oil composition is used for gasoline engines)
and
high detergency at a high temperature (which is required when the lubricating
1' 5 oil composition is used for diesel engines). The addition of a molybdenum-
containing compound further improves detergency at a high temperature.
While the present invention has been described with reference to specific
embodiments, this application is intended to cover those various changes and
substitutions that may be made by those skilled in the art without departing
from the spirit and scope of the appended claims.
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