U.S. patent application number 10/353169 was filed with the patent office on 2004-02-26 for lubricating oil compositions for internal combustion engines with improved wear performance.
Invention is credited to Baillargeon, David J., Buck, William H., Deckman, Douglas E., Maxwell, William D., Winemiller, Mark D..
Application Number | 20040038833 10/353169 |
Document ID | / |
Family ID | 27669097 |
Filed Date | 2004-02-26 |
United States Patent
Application |
20040038833 |
Kind Code |
A1 |
Deckman, Douglas E. ; et
al. |
February 26, 2004 |
Lubricating oil compositions for internal combustion engines with
improved wear performance
Abstract
The present invention concerns a lubricating oil composition
comprising an oil of lubricating viscosity; about 0.05 to about 5
weight percent of an organo molybdenum compound; and about 0.1 to
about 12 weight percent of a borated polyisobutenyl mono- and
bis-succinimide wherein the polyisobutenyl group has a molecular
weight (Mn) from about 500 to about 2300.
Inventors: |
Deckman, Douglas E.;
(Mullica Hill, NJ) ; Buck, William H.; (West
Chester, PA) ; Maxwell, William D.; (Clarksboro,
NJ) ; Winemiller, Mark D.; (Clarksboro, NJ) ;
Baillargeon, David J.; (Cherry Hill, NJ) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
27669097 |
Appl. No.: |
10/353169 |
Filed: |
January 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60353735 |
Jan 31, 2002 |
|
|
|
Current U.S.
Class: |
508/192 |
Current CPC
Class: |
C10N 2010/12 20130101;
C10M 2203/065 20130101; C10M 141/10 20130101; C10N 2030/08
20130101; C10N 2030/10 20130101; C10N 2040/253 20200501; C10M
2205/0285 20130101; C10M 2219/068 20130101; C10N 2030/14 20130101;
C10N 2060/14 20130101; C10M 2227/09 20130101; C10M 2223/047
20130101; C10M 2223/045 20130101; C10N 2030/06 20130101; C10M
141/12 20130101; C10N 2030/42 20200501; C10M 163/00 20130101; C10M
2203/1025 20130101; C10M 2215/28 20130101; C10N 2020/04 20130101;
C10M 169/045 20130101; C10N 2040/255 20200501; C10M 169/04
20130101; C10M 2207/0285 20130101; C10M 141/08 20130101 |
Class at
Publication: |
508/192 |
International
Class: |
C10M 101/00 |
Claims
What is claimed is:
1. A lubricant additive comprising: (a) at least one organo
molybdenum compound; and (b) borated polyisobutenyl mono- and
bis-succinimide wherein the polyisobutenyl group has a molecular
weight (Mn) from about 500 to about 2300.
2. A lubricating oil composition comprising: (a) an oil of
lubricating viscosity; (b) about 0.05 to about 5 weight percent of
an organo molybdenum compound; and (c) about 0.1 to about 12 weight
percent of a borated polyisobutenyl mono- and bis-succinimide
wherein the polyisobutenyl group has a molecular weight (Mn) from
about 500 to about 2300.
3. The lubricating oil of claim 2 wherein the oil of lubricating
viscosity is selected from the group consisting of Group II, Group
III, and synthetic base stocks.
4. The lubricating oil of claim 3 wherein the synthetic base stock
is a polyalphaolefin.
5. The lubricating oil of claim 3 additionally comprising at least
one co-basestock selected from the group consisting of hydrocarbyl
aromatic and ester base stocks.
6. The lubricating oil of claim 3 wherein the molybdenum compound
is at least one compound selected from the group consisting of
molybdenum phosphorodithioates, molybdenum complexes of amines,
alcohols and/or esters, molybdenum dithiocarbamates, and molybdenum
(trimeric) dithiocarbamates.
7. The lubricating oil of claim 6 wherein the organic molybdenum
compound is present in an amount of about 0.1 to about 3 weight
percent.
8. The lubricating oil composition of claim 7 where in the borated
polyisobutenyl mono- and bis-succinimide compound is present in an
amount of about 0.5 to about 8 weight percent.
9. The lubricating oil of claim 8 wherein the lubricating oil is a
Group II, Group III, or Gas-to-Liquids base stock.
10. The lubricating oil of any one of the claims 2 through 9
wherein the borated polyisobutenyl mono- and bis-succinimide is
present at about 20% of the total borated succinimide.
11. A method of improving wear performance of a lubricating oil
composition comprising the step of adding the following to the
lubricating oil: (i) about 0.05 to about 5 weight percent of an
organo molybdenum compound; and (ii) about 0.1 to about 12 weight
percent of a borated polyisobutenyl mono- and bis-succinimide
wherein the polyisobutenyl group has a molecular weight (Mn) from
about 500 to about 2300.
12. The borated polyisobutenyl mono- and bis-succinimide of claim 1
wherein the mono-succinimide is present at about 20% of the total
borated succinimide.
13. A method of reducing lead loss under catalytic oxidation test
conditions of a lubricating oil composition comprising the step of
adding the following to the lubricating oil: (i) about 0.05 to
about 5 weight percent of an organo molybdenum compound; and (ii)
about 0.1 to about 12 weight percent of a borated polyisobutenyl
mono- and bis-succinimide wherein the polyisobutenyl group has a
molecular weight (Mn) from about 500 to about 2300.
14. A method of improving viscosity increase control under
high-temperature oxidizing conditions of a lubricating oil
composition comprising the step of adding the following to the
lubricating oil: (i) about 0.05 to about 5 weight percent of an
organo molybdenum compound; and (ii) about 0.1 to about 12 weight
percent of a borated polyisobutenyl mono- and bis-succinimide
wherein the polyisobutenyl group has a molecular weight (Mn) from
about 500 to about 2300.
15. The lubricating oil of claim 6 where the molybdenum compound is
present at a concentration sufficient to provide 20 ppm to 1000 ppm
molybdenum.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to lubricating oil compositions
suitable for use in internal combustion engines.
[0003] 1. Background
[0004] Lubricating oils for internal combustion engines contain in
addition to at least one base lubricating oil, additives which
enhance the performance of the lubricating oil. A variety of
additives such as detergents, dispersants, friction reducers,
viscosity index improvers, antioxidants, corrosion inhibitors,
antiwear additives, pour point depressants, seal swell additives,
and antifoam agents are used in lubricating oil compositions.
[0005] During engine operation, oil insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposit on metal surfaces. Dispersants may
be ashless or ash-forming in nature. So called ashless dispersants
are organic materials that form substantially no ash upon
combustion.
[0006] A known class of dispersants are the alkenylsuccinic
derivatives, typically produced by the reaction of a long chain
substituted alkenyl succinic compound, usually a substituted
succinic anhydride, with a polyhydroxy or polyamino compound. The
long chain group constituting the oleophilic portion of the
molecule which confers solubility in the oil, is normally a
polyolefin, such as ethylene-propylene polymer or polyisobutylene
group. Many examples of this type of dispersant are well known
commercially and in the literature. Exemplary U.S. patents
describing such dispersants are U.S. Pat. Nos. 3,172,892;
3,2145,707; 3,219,666; 3,316,177; 3,341,542; 3,444,170; 3,454,607;
3,541,012; 3,630,904; 3,632,511; 3,787,374 and 4,234,435;
3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209, and
5,084,197. Other types of dispersants are described in U.S. Pat.
Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554; 3,438,757;
3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277; 3,725,480;
3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565; 3,666,730;
3,687,849; 3,702,300; 4,100,082; 5,705,458. A further description
of dispersants may be found, for example, in European Patent
Application No. 471071, to which reference is made for this
purpose. Each of the aforementioned patents is incorporated herein
by reference in its entirety.
[0007] Antiwear and extreme pressure additives are also used in
lubricating oil compositions. These additives help reduce wear of
metal engine parts. Zinc dialkyldithiophosphate (ZDDP) has been
used as an antiwear agent for many years. Use of alkylthiocarbamoyl
compounds (bis(dibutyl)thiocarbamoyl, for example) in combination
with a molybdenum compound (oxymolybdenum
diisopropylphosphorodithioate sulfide, for example) and a
phosphorous ester (dibutyl hydrogen phosphite, for example) as
antiwear additives in lubricants is disclosed in U.S. Pat. No.
4,501,678, incorporated herein by reference in its entirety.
[0008] As high performance engines place more demands on
lubricating oils, there is a need for oils with improved dispersant
function.
SUMMARY OF THE INVENTION
[0009] The present invention concerns a lubricating oil composition
comprising an oil of lubricating viscosity; about 0.05 to about 5
weight percent of an organo molybdenum compound; and about 0.1 to
about 12 weight percent of a borated polyisobutenyl mono- and
bis-succinimide wherein the polyisobutenyl group has a molecular
weight (Mn) from about 500 to about 2300.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a plot of coefficient of friction as a function of
temperature for various compositions.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Engine oils contain a base lube oil and a variety of
additives. These additives include detergents, dispersants,
friction reducers, viscosity index improvers, antioxidants,
corrosion inhibitors, antiwear additives, pour point depressants,
seal compatibility additives, and antifoam agents. To be effective,
these additives must be oil-soluble or oil-dispersible. By
oil-soluble, it is meant that the compound is soluble in the base
oil or lubricating oil composition under normal blending
conditions.
[0012] The present invention concerns a lubricating oil composition
comprising an oil of lubricating viscosity; about 0.05 to about 5
weight percent of an organo molybdenum compound; and about 0.1 to
about 12 weight percent of a borated polyisobutenyl mono- and
bis-succinimide wherein the polyisobutenyl group has a molecular
weight (Mn) from about 500 to about 2300. The combination of these
ingredients shows a significant improvement in engine wear
protection and lube related oxidation performance.
[0013] Another aspect of this invention concerns an additive
composition comprising an oil of lubricating viscosity; about 0.02
to about 5 weight percent of an organo molybdenum compound; and
about 0.1 to about 12 weight percent of a borated polyisobutenyl
mono- and bis-succinimide wherein the polyisobutenyl group has a
molecular weight (Mn) from about 500 to about 2300. Lube oil
compositions comprising this additive also show a significant
improvements in engine wear protection and lube related oxidation
performance. A further aspect of the invention encompasses a method
of preparing lubricant oil compositions of the present
invention.
[0014] Organic molybdenum sources useful in the present invention
include all those commonly available organic molybdenum
compositions known in the art, including, but not limited to
molybdenum phosphorodithioates, molybdenum complexes of various
amines and/or alcohols or esters, molybdenum dithiocarbamates,
and/or molybdenum (trimeric) dithiocarbamates or mixtures thereof.
Of these, the above molybdenum complexes, molybdenum
dithiocarbamates are preferred. Preferred concentration ranges of
the molybdenum compounds in the lubricating oil composition range
from about 0.05 to about 5 wt % of such molybdenum sources can be
effectively used, with concentration ranges of about 0.1 to about 3
wt % often being more preferred, and with concentration ranges of
about 0.15 to about 2 wt % often being most preferred.
[0015] The borated moderate molecular weight polyisobutenyl mono-
and bis- succinimide compounds of the present invention have an
optimal molecular weight range of approximately 500 to about 2300,
or preferably 1000 to about 1600, (Mn) for the polyisobutylene
portion of the compound. It is observed that a compound of the
present invention (approximately 1300 Mn polyisobutylene derived),
when used in conjunction with the other elements of this invention,
clearly provide improved performance characteristics when compared
to the borated higher molecular weight (approximately 2500 Mn
polyisobutylene derived) primarily bis- succinimide ashless
dispersant. Preferred concentrations of the dispersant(s) of the
present invention (or mixtures of such dispersants) are about 0.1
to about 12 weight percent or more. Often concentrations of about
0.5 to about 8 weight percent or more are preferred and
concentrations of about 2 to about 8 weight percent are most
preferred. We believe that at least a significant portion of the
succinimide be a mono-succinimide or a mixture of mono and
bis-succinimide for maximum performance benefits as described in
this instant invention. At least 20% of the mixture is preferably
mono-succinimide to provide the synergism of this invention.
[0016] It is often advantageous to use mixtures of the dispersants
described above and other related dispersants, such as those that
are boron-free, those that are primarily of higher molecular
weight, those that consist of primarily mono-succinimide,
bis-succinimide, or mixtures of above, those made with different
amines, those that are end-capped, dispersants wherein the
back-bone is derived from polymers such as other polyolefins other
than polyisobutylene, such as ethylene, propylene, and all mixtures
thereof and the like.
[0017] The above products can be post-reacted with various reagents
such as sulfur, oxygen, formaldehyde, carboxylic acids such as
oleic acid, anhydrides, polycyclic carbonates, and boron compounds
such as borate esters or highly borated dispersants. The
dispersants can be borated with from about 0.1 to about 5 moles of
boron per mole of dispersant reaction product.
[0018] Other aspects of this invention are the additional
performance advantages for wear protection (i.e., anti-wear
performance) in low- to non-phosphorus lubricant compositions. Low-
to non-phosphorus encompasses compositions in which the phosphorus
concentration is 0% to about 0.05% by weight of the lubricant
composition.
[0019] Base Oil
[0020] A wide range of lubricating oils is known in the art.
Lubricating oils that are useful in the present invention are both
natural oils and synthetic oils. Natural and synthetic oils (or
mixtures thereof) can be used unrefined, refined, or rerefined (the
latter is also known as reclaimed or reprocessed oil). Unrefined
oils are those obtained directly from a natural or synthetic source
and used without added purification. These include shale oil
obtained directly from retorting operations, petroleum oil obtained
directly from primary distillation, and ester oil obtained directly
from an esterification process. Refined oils are similar to the
oils discussed for unrefined oils except refined oils are subjected
to one or more purification steps to improve the at least one
lubricating oil property. One skilled in the art is familiar with
many purification processes. These processes include solvent
extraction, secondary distillation, acid extraction, base
extraction, filtration, and percolation. Rerefined oils are
obtained by processes analogous to refined oils but using an oil
that has been previously used.
[0021] Groups I, II, III, IV and V are broad categories of base oil
stocks developed and defined by the American Petroleum Institute
(API Publication 1509; www.API.org) to create guidelines for
lubricant base oils. Group I base stock generally have a viscosity
index of between about 80 to 120 and contains greater than about
0.03% sulfur and/or less than about 90% saturates. Group II base
stocks generally have a viscosity index of between about 80 to 120,
and contain less than or equal to about 0.03% sulfur and greater
than or equal to about 90% saturates. Group III stock generally has
a viscosity index greater than about 120 and contain less than or
equal to about 0.03% sulfur and greater than about 90% saturates.
Group IV includes polyalphaolefins (POA). Group V base stock
includes base stocks not included in Groups I-IV. The table below
summarizes properties of each of these five groups.
1 Base Stock Properties Saturates Sulfur Viscosity Index Group I
<90 &/or >0.03% & .gtoreq.80 & <120 Group II
.gtoreq.90 & .ltoreq.0.03% & .gtoreq.80 & <120 Group
III .gtoreq.90 & .ltoreq.0.03% & .gtoreq.120 Group IV
Defined as polyalphaolefins (PAO) Group V All other base oil stocks
not included in Groups I, II, III, or IV
[0022] Natural oils include animal oils, vegetable oils (castor oil
and lard oil, for example), and mineral oils. In regard to animal
and vegetable oils, those possessing favorable thermal oxidative
stability can be used. Of the natural oils, mineral oils are
preferred. Mineral oils vary widely as to their crude source, for
example, as to whether they are paraffinic, naphthenic, or mixed
paraffinic-naphthenic. Oils derived from coal or shale are also
useful in the present invention. Natural oils vary also as to the
method used for their production and purification, for example,
their distillation range and whether they are straight run or
cracked, hydrorefined, or solvent extracted.
[0023] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
for example). Polyalphaolefin (PAO) oil base stocks are a commonly
used synthetic hydrocarbon oil. By way of example, PAOs derived
from C.sub.8, C.sub.10, C.sub.12, C.sub.14 olefins or mixtures
thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064;
and 4,827,073, which are incorporated herein by reference in their
entirety.
[0024] The number average molecular weights of the PAOs, which are
known materials and generally available on a major commercial scale
from suppliers such as ExxonMobil Chemical Company,
Chevron-Phillips, BP-Amoco, and others, typically vary from about
250 to about 3,000, although PAO's may be made in viscosities up to
about 100 cSt (100.degree. C.). The PAOs are typically comprised of
relatively low molecular weight hydrogenated polymers or oligomers
of alphaolefins which include, but are not limited to, C.sub.2 to
about C.sub.32 alphaolefins with C.sub.8 to about C.sub.16
alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like,
being preferred. The preferred polyalphaolefins are poly-1-octene,
poly-1-decene and poly-1-dodecene and mixtures thereof and mixed
olefin-derived polyolefins. However, the dimers of higher olefins
in the range of C.sub.14 to C.sub.18 may be used to provide low
viscosity basestocks of acceptably low volatility. Depending on the
viscosity grade and the starting oligomer, the PAOs may be
predominantly trimers and tetramers of the starting olefins, with
minor amounts of the higher oligomers, having a viscosity range of
about 1.5 to 12 cSt.
[0025] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as the Friedel-Crafts catalysts
including, for example, aluminum trichloride, boron trifluoride or
complexes of boron trifluoride with water, alcohols such as
ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods
disclosed by U.S. Pat. No. 4,149,178 or U.S. Pat. No. 3,382,291 may
be conveniently used herein. Other descriptions of PAO synthesis
are found in the following U.S. Pat. Nos. 3,742,082; 3,769,363;
3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355;
4,956,122; and 5,068,487. The dimers of the C.sub.14 to C.sub.18
olefins are described in U.S. Pat. No. 4,218,330. All of the
aforementioned patents are incorporated by reference herein in
their entirety.
[0026] Other useful synthetic lubricating oils may also be
utilized, for example, those described in the work "Synthetic
Lubricants", Gunderson and hart, Reinhold Publ. Corp., New York,
1962, which is incorporated in its entirety.
[0027] In alkylated aromatic stocks (hydrocarbyl aromatics, for
example), the alkyl substituents are typically alkyl groups of
about 8 to 25 carbon atoms, usually from about 10 to 18 carbon
atoms and up to three such substituents may be present, as
described for the alkyl benzenes in ACS Petroleum Chemistry
Preprint 1053-1058, "Poly n-Alkylbenzene Compounds: A Class of
Thermally Stable and Wide Liquid Range Fluids", Eapen et al, Phila.
1984. Tri-alkyl benzenes may be produced by the cyclodimerization
of 1-alkynes of 8 to 12 carbon atoms as described in U.S. Pat. No.
5,055,626. Other alkylbenzenes are described in European Patent
Application No. 168534 and U.S. Pat. No. 4,658,072. Alkylbenzenes
are used as lubricant basestocks, especially for low-temperature
applications (arctic vehicle service and refrigeration oils) and in
papermaking oils. They are commercially available from producers of
linear alkylbenzenes (LABs) such as Vista Chem. Co, Huntsman
Chemical Co., Chevron Chemical Co., and Nippon Oil Co. The linear
alkylbenzenes typically have good low pour points and low
temperature viscosities and VI values greater than 100 together
with good solvency for additives. Other alkylated aromatics which
may be used when desirable are described, for example, in
"Synthetic Lubricants and High Performance Functional Fluids",
Dressler, H., chap 5, (R. L. Shubkin (Ed.)), Marcel Dekker, N.Y.
1993.
[0028] Other useful lubricant oil base stocks include wax isomerate
base stocks and base oils, comprising hydroisomerized waxy stocks
(e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker
bottoms, etc.), hydroisomerized Fischer-Tropsch waxes,
Gas-to-Liquids (GTL) base stocks and base oils, and other wax
isomerate hydroisomerized base stocks and base oils, or mixtures
thereof. Fischer-Tropsch waxes, the high boiling point residues of
Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with
very low sulfur content. The hydroprocessing used for the
production of such base stocks may use an amorphous
hydrocracking/hydroisomerization catalyst, such as one of the
specialized lube hydrocracking (LHDC) catalysts or a crystalline
hydrocracking/hydroisomerization catalyst, preferably a zeolitic
catalyst. For example, one useful catalyst is ZSM-48 as described
in U.S. Pat. No. 5,075,269. Processes for making
hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in
U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as
well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and
1,390,359. Particularly favorable processes are described in
European Patent Application Nos. 464546 and 464547. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172
and 4,943,672. Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax
derived base oils, and other wax-derived hydroisomerized (wax
isomerate) base oils be advantageously used in the instant
invention, and may have useful kinematic viscosities at 100.degree.
C. of about 3 cSt to about 50 cSt, preferably about 3 cSt to about
30 cSt, more preferably about 3.5 cSt to about 25 cSt, as
exemplified by GTL 4 with kinematic viscosity of about 4.0 cSt at
100.degree. C. and a viscosity index of about 141. These
Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base
oils, and other wax-derived hydroisomerized base oils may have
useful pour points of about -20.degree. C. or lower, and under some
conditions may have advantageous pour points of about -25.degree.
C. or lower, with useful pour points of about -30.degree. C. to
about -40.degree. C. or lower. Useful compositions of
Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived base
oils, and wax-derived hydroisomerized base oils are recited in U.S.
Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and are
incorporated herein in their entirety by reference.
[0029] Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived
base oils, have a beneficial kinematic viscosity advantage over
conventional Group II and Group III base oils, which may be very
advantageously used with the instant invention. Gas-to-Liquids
(GTL) base oils can have significantly higher kinematic
viscosities, up to about 20-50 cSt at 100.degree. C., whereas by
comparison commercial Group II base oils can have kinematic
viscosities, up to about 15 cSt at 100.degree. C., and commercial
Group III base oils can have kinematic viscosities, up to about 10
cSt at 100.degree. C. The higher kinematic viscosity range of
Gas-to-Liquids (GTL) base oils, compared to the more limited
kinematic viscosity range of Group II and Group III base oils, in
combination with the instant invention can provide additional
beneficial advantages in formulating lubricant compositions. Also,
the exceptionally low sulfur content of Gas-to-Liquids (GTL) base
oils, and other wax-derived hydroisomerized base oils, in
combination with the low sulfur content of suitable olefin
oligomers and/or alkyl aromatics base oils, and in combination with
the instant invention can provide additional advantages in
lubricant compositions where very low overall sulfur content can
beneficially impact lubricant performance.
[0030] Alkylene oxide polymers and interpolymers and their
derivatives containing modified terminal hydroxyl groups obtained
by, for example, esterification or etherification are useful
synthetic lubricating oils. By way of example, these oils may be
obtained by polymerization of ethylene oxide or propylene oxide,
the alkyl and aryl ethers of these polyoxyalkylene polymers
(methyl-polyisopropylene glycol ether having an average molecular
weight of about 1000, diphenyl ether of polyethylene glycol having
a molecular weight of about 500-1000, and the diethyl ether of
polypropylene glycol having a molecular weight of about 1000 to
1500, for example) or mono- and polycarboxylic esters thereof (the
acidic acid esters, mixed C.sub.3-8 fatty acid esters, or the
C.sub.13Oxo acid diester of tetraethylene glycol, for example).
[0031] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of mono-carboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0032] Particularly useful synthetic esters are those which are
obtained by reacting one or more polyhydric alcohols, preferably
the hindered polyols (such as the neopentyl polyols e.g. neopentyl
glycol, trimethylol ethane, 2-methyl-2-propyl-1,3-propanediol,
trimethylol propane, pentaerythritol and dipentaerythritol) with
alkanoic acids containing at least about 4 carbon atoms such as
C.sub.5 to C.sub.30 acids (such as saturated straight chain fatty
acids including caprylic acid, capric acid, lauric acid, myristic
acid, palmitic acid, stearic acid, arachic acid, and behenic acid,
or the corresponding branched chain fatty acids or unsaturated
fatty acids such as oleic acid, or mixtures thereof).
[0033] Suitable synthetic ester components include esters of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more
monocarboxylic acids containing from about 5 to about 10 carbon
atoms. Such esters are widely available commercially, for example,
the Mobil P-41 and P-5 1 esters (ExxonMobil Chemical Company).
[0034] Silicon-based oils are another class of useful synthetic
lubricating oils. These oils include polyalkyl-, polyaryl-,
polyalkoxy-, and polyaryloxy-siloxane oils and silicate oils.
Examples of suitable silicon-based oils include tetraethyl
silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-hexyl)silicate, tetra-(p-tert-butylphenyl)
silicate, hexyl-(4-methyl-2-pentoxy) disiloxane, poly(methyl)
siloxanes, and poly-(methyl-2-mehtylphenyl) siloxanes.
[0035] Another class of synthetic lubricating oil is esters of
phosphorous-containing acids. These include, for example, tricresyl
phosphate, trioctyl phosphate, diethyl ester of decanephosphonic
acid.
[0036] Another class of oils includes polymeric tetrahydrofurans
and the like.
[0037] In the present invention, base stocks having a high
paraffinic nature are preferred. For example, Group II and/or Group
III hydroprocessed or hydrocracked base stocks, or their synthetic
counterparts such as polyalphaolefin lubricating oils, or similar
base oils or mixtures of similar base oils are often preferred as
lubricating base stocks when used in conjunction with the
components of the above inventions. Preferably, at least about 20%
of the total composition should consist of such Group II or Group
III base stocks, with at least about 30%, often being more
preferable, and more than about 80% often being even more
preferable. Gas to liquid base stocks can also be preferentially
used with the components of this invention as a portion or all of
the base stocks used to formulate the finished lubricant. A mixture
of all or some of such base may be used and may be preferred. In
one preferred mode, the base oil that is added to lubricating
systems is comprised of primarily Group II and/or Group III base
stocks. Preferably, 20% of such Group II and/or Group III base
stocks may be used to achieve the advantages of this invention.
Optionally in this mode, lesser quantities of alternate fluids such
as the above described hydrocarbyl aromatics (C.sub.16
monoalkylated naphthalene, for example) may be added.
[0038] Co-base stocks can also advantageously used at
concentrations lower than those of the primary base stock(s)
without detracting from the elements of this invention. These
co-base stocks include polyalphaolefin oligomeric low and moderate
and high viscosity oils, dibasic acid esters, polyol esters, other
hydrocarbon oils, supplementary hydrocarbyl aromatics and the like.
These co-base stocks can also include some quantity of
decene-derived trimers and tetramers, and also some quantity of
Group I base stocks, provided that the above Group II and or Group
III type base stocks predominate and make up at least about 50% of
the total base stocks contained in fluids of the present
invention.
[0039] Performance Additives
[0040] The instant invention can be used with additional lubricant
components in effective amounts in lubricant compositions, such as
for example polar and/or non-polar lubricant base oils, and
performance additives such as for example, but not limited to,
oxidation inhibitors, metallic and non-metallic dispersants,
metallic and non-metallic detergents, corrosion and rust
inhibitors, metal deactivators, anti-wear agents (metallic and
non-metallic, phosphorus-containing and non-phosphorus,
sulfur-containing and non-sulfur types), extreme pressure additives
(metallic and non-metallic, phosphorus-containing and
non-phosphorus, sulfur-containing and non-sulfur types),
anti-seizure agents, pour point depressants, wax modifiers,
viscosity modifiers, seal compatibility agents, friction modifiers,
lubricity agents, anti-staining agents, chromophoric agents,
defoamants, demulsifiers, and others. For a review of many commonly
used additives see Klamann in Lubricants and Related Products,
Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0, which
also gives a good discussion of a number of the lubricant additives
discussed mentioned below. Reference is also made "Lubricant
Additives" by M. W. Ranney, published by Noyes Data Corporation of
Parkridge, N.J. (1973).
[0041] Antiwear and Extreme Pressure Additives
[0042] Additional antiwear additives may be used with the present
invention. While there are many different types of antiwear
additives, for several decades the principal antiwear additive for
internal combustion engine crankcase oils is a metal
alkylthiophosphate and more particularly a metal
dialkyldithiophosphate in which the primary metal constituent is
zinc, or zinc dialkyldithiophosphate (ZDDP). ZDDP compounds
generally are of the formula Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.- 2
where R.sup.1 and R.sup.2 are C.sub.1-C.sub.18 alkyl groups,
preferably C.sub.2-C.sub.12 alkyl groups. These alkyl groups may be
straight chain or branched. For example, suitable alkyl groups
include isopropyl, 4-methyl-2-pentyl, and isooctyl. The ZDDP is
typically used in amounts of from about 0.4% to about 1.4 wt % of
the total lube oil composition, although more or less can often be
used advantageously.
[0043] However, it is found that the phosphorus from these
additives has a deleterious effect on the catalyst in catalytic
converters and also on oxygen sensors in automobiles. One way to
minimize this effect is to replace some or all of the ZDDP with
phosphorus-free antiwear additives.
[0044] A variety of non-phosphorous additives are also used as
antiwear additives. Sulfurized olefins are useful as antiwear and
EP additives. Sulfur-containing olefins can be prepared by
sulfurization or various organic materials including aliphatic,
arylaliphatic or alicyclic olefinic hydrocarbons containing from
about 3 to 30 carbon atoms, preferably 3-20 carbon atoms. The
olefinic compounds contain at least one non-aromatic double bond.
Such compounds are defined by the formula
R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6
[0045] where each of R.sup.3-R.sup.6 are independently hydrogen or
a hydrocarbon radical. Preferred hydrocarbon radicals are alkyl or
alkenyl radicals. Any two of R.sup.3-R.sup.6 may be connected so as
to form a cyclic ring. Additional information concerning sulfurized
olefins and their preparation can be found in U.S. Pat. No.
4,941,984, incorporated by reference herein in its entirety.
[0046] The use of polysulfides of thiophosphorous acids and
thiophosphorous acid esters as lubricant additives is disclosed in
U.S. Pat. Nos. 2,443,264; 2,471,115; 2,526,497; and 2,591,577.
Addition of phosphorothionyl disulfides as an antiwear,
antioxidant, and EP additives is disclosed in U.S. Pat. No.
3,770,854. Use of alkylthiocarbamoyl compounds
(bis(dibutyl)thiocarbamoyl, for example) in combination with a
molybdenum compound (oxymolybdenum diisopropylphosphorodithioate
sulfide, for example) and a phosphorous ester (dibutyl hydrogen
phosphite, for example) as antiwear additives in lubricants is
disclosed in U.S. Pat. No. 4,501,678. U.S. Pat. No. 4,758,362
discloses use of a carbamate additive to provide improved antiwear
and extreme pressure properties. The use of thiocarbamate as an
antiwear additive is disclosed in U.S. Pat. No. 5,693,598.
Thiocarbamate/molybdenum complexes such as molysulfur alkyl
dithiocarbamate trimer complex (R.dbd.C.sub.8-C.sub.18 alkyl) are
also useful antiwear agents. Each of the above mentioned patents is
incorporated by reference herein in its entirety.
[0047] Esters of glycerol may be used as antiwear agents. For
example, mono-, di, and tri-oleates, mono-palmitates and
mono-myristates may be used.
[0048] ZDDP is combined with other compositions that provide
antiwear properties. U.S. Pat. No. 5,034,141 discloses that a
combination of a thiodixanthogen compound (octylthiodixanthogen,
for example) and a metal thiophosphate (ZDDP, for example) can
improve antiwear properties. U.S. Pat. No. 5,034,142 discloses that
use of a metal alkyoxyalkylxanthate (nickel ethoxyethylxanthate,
for example) and a dixanthogen (diethoxyethyl dixanthogen, for
example) in combination with ZDDP improves antiwear properties.
[0049] Antiwear additives may be used in an amount of about 0.01 to
6 wt %, preferably about 0.01 to 4 wt %.
[0050] Viscosity Index Improvers
[0051] Viscosity index improvers (also known as VI improvers,
viscosity modifiers, and viscosity improvers) provide lubricants
with high and low temperature operability. These additives impart
shear stability at elevated temperatures and acceptable viscosity
at low temperatures.
[0052] Suitable viscosity index improvers include high molecular
weight hydrocarbons, polyesters and viscosity index improver
dispersants that function as both a viscosity index improver and a
dispersant. Typical molecular weights of these polymers are between
about 10,000 to 1,000,000, more typically about 20,000 to 500,00,
and even more typically between about 50,000 and 200,000.
[0053] Examples of suitable viscosity index improvers are polymers
and copolymers of methacrylate, butadiene, olefins, or alkylated
styrenes. Polyisobutylene is a commonly used viscosity index
improver. Another suitable viscosity index improver is
polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity index improvers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, and polyacrylates (copolymers
of various chain length acrylates, for example). Specific examples
include styrene-isoprene or styrene-butadiene based polymers of
about 50,000 to 200,000 molecular weight.
[0054] Viscosity index improvers may be used in an amount of about
0.01 to 6 weight percent, preferably about 0.01 to 4 weight
percent.
[0055] Antioxidants
[0056] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricating oil compositions. See,
Klamann in Lubricants and Related Products, op cite, and U.S. Pat.
Nos. 4,798,684 and 5,084,197, for example, the disclosures of which
are incorporated by reference herein in their entirety. Useful
antioxidants include hindered phenols. These phenolic antioxidants
may be ashless (metal-free) phenolic compounds or neutral or basic
metal salts of certain phenolic compounds. Typical phenolic
antioxidant compounds are the hindered phenolics which are the ones
which contain a sterically hindered hydroxyl group, and these
include those derivatives of dihydroxy aryl compounds in which the
hydroxyl groups are in the o- or p-position to each other. Typical
phenolic antioxidants include the hindered phenols substituted with
C.sub.6+alkyl groups and the alkylene coupled derivatives of these
hindered phenols. Examples of phenolic materials of this type
2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol;
2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant invention. Examples of ortho coupled
phenols include: 2,2'-bis(6-t-butyl-4-heptyl phenol);
2,2'-bis(6-t-butyl-4-octyl phenol); and
2,2'-bis(6-t-butyl-4-dodecyl phenol). Para coupled bis phenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0057] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.10 is H, alkyl, aryl or R.sup.11S(O).sub.xR.sup.12 where
R.sup.11 is an alkylene, alkenylene, or aralkylene group, R.sup.12
is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and
x is 0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to
about 20 carbon atoms, and preferably contains from 6 to 12 carbon
atoms. The aliphatic group is a saturated aliphatic group.
Preferably, both R.sup.8 and R.sup.9 are aromatic or substituted
aromatic groups, and the aromatic group may be a fused ring
aromatic group such as naphthyl. Aromatic groups R.sup.8 and
R.sup.9 may be joined together with other groups such as S.
[0058] Typical aromatic amines antioxidants have alkyl substituent
groups of at least about 6 carbon atoms. Examples of aliphatic
groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally,
the aliphatic groups will not contain more than about 14 carbon
atoms. The general types of amine antioxidants useful in the
present compositions include diphenylamines, phenyl
naphthyl-amines, phenothiazines, imidodibenzyls and diphenyl
phenylene diamines. Mixtures of two or more aromatic amines are
also useful. Polymeric amine antioxidants can also be used.
Particular examples of aromatic amine antioxidants useful in the
present invention include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthy- lamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0059] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants. Low sulfur peroxide
decomposers are useful as antioxidants.
[0060] Another class of antioxidant used in lubricating oil
compositions is oil-soluble copper compounds. Any oil-soluble
suitable copper compound may be blended into the lubricating oil.
Examples of suitable copper antioxidants include copper
dihydrocarbyl thio or dithio-phosphates and copper salts of
carboxylic acid (naturally occurring or synthetic). Other suitable
copper salts include copper dithiacarbamates, sulphonates,
phenates, and acetylacetonates. Basic, neutral, or acidic copper
Cu(I) and or Cu(II) salts derived from alkenyl succinic acids or
anhydrides are know to be particularly useful.
[0061] Preferred antioxidants include hindered phenols, arylamines,
low sulfur peroxide decomposers and other related components. These
antioxidants may be used individually by type or in combination
with one another. Such additives may be used in an amount of about
0.01 to 5 weight percent, preferably about 0.01 to 1.5 weight
percent.
[0062] Detergents
[0063] Detergents are commonly used in lubricating compositions. A
typical detergent is an anionic material that contains a long chain
oleophillic portion of the molecule and a smaller anionic or
oleophobic portion of the molecule. The anionic portion of the
detergent is typically derived from an organic acid such as a
sulfur acid, carboxylic acid, phosphorous acid, phenol, or mixtures
thereof. The counter ion is typically an alkaline earth or alkali
metal.
[0064] Salts that contain a substantially stochiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) with an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly
overbased, or highly overbased.
[0065] It is desirable for at least some detergent to be overbased.
Overbased detergents help neutralize acidic impurities produced by
the combustion process and become entrapped in the oil. Typically,
the overbased material has a ratio of metallic ion to anionic
portion of the detergent of about 1.05:1 to 50:1 on an equivalent
basis. More preferably, the ratio is from about 4:1 to about 25:1.
The resulting detergent is an overbased detergent that will
typically have a TBN of about 150 or higher, often about 250 to 450
or more. Preferably, the overbasing cation is sodium, calcium, or
magnesium. A mixture of detergents of differing TBN can be used in
the present invention.
[0066] Preferred detergents include the alkali or alkaline earth
metal salts of sulfates, phenates, carboxylates, phosphates, and
salicylates.
[0067] Sulfonates may be prepared from sulfonic acids that are
typically obtained by sulfonation of alkyl substituted aromatic
hydrocarbons. Hydrocarbon examples include those obtained by
alkylating benzene, toluene, xylene, naphthalene, biphenyl and
their halogenated derivatives (chlorobenzene, chlorotoluene, and
chloronaphthalene, for example). The alkylating agents typically
have about 3 to 70 carbon atoms. The alkaryl sulfonates typically
contain about 9 to about 80 carbon or more carbon atoms, more
typically from about 16 to 60 carbon atoms.
[0068] Klamann in Lubricants and Related Products, op cit discloses
a number of overbased metal salts of various sulfonic acids which
are useful as detergents and dispersants in lubricants. The book
entitled "Lubricant Additives", C. V. Smallheer and R. K. Smith,
published by the Lezius-Hiles Co. of Cleveland, Ohio (1967),
similarly discloses a number of overbased sulfonates which are
useful as dispersants/detergents.
[0069] Akaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH).sub.2, BaO, Ba(OH).sub.2,
MgO, Mg(OH).sub.2, for example) with an alkyl phenol or sulfurized
alkylphenol. Useful alkyl groups include straight chain or branched
C.sub.1-C.sub.30 alkyl groups, preferably, C.sub.4-C.sub.20.
Examples of suitable phenols include isobutylphenol,
2-ethylhexylphenol, nonylphenol, 1-ethyldecylphenol, and the like.
It should be noted that starting alkylphenols may contain more than
one alkyl substituent that are each independently straight chain or
branched. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These
methods include heating a mixture of alkylphenol and sulfurizing
agent (including elemental sulfur, sulfur halides such as sulfur
dichloride, and the like) and then reacting the sulfurized phenol
with an alkaline earth metal base.
[0070] Metal salts of carboxylic acids are also useful as
detergents. These carboxylic acid detergents may be prepared by
reacting a basic metal compound with at least one carboxylic acid
and removing free water from the reaction product. These compounds
may be overbased to produce the desired TBN level. Detergents made
from salicylic acid are one preferred class of detergents derived
from carboxylic acids. Useful salicylates include long chain alkyl
salicylates. One useful family of compositions is of the formula
1
[0071] where R is a hydrogen atom or an alkyl group having 1 to
about 30 carbon atoms, n is an integer from 1 to 4, and M is an
alkaline earth metal. Preferred R groups are alkyl chains of at
least about C.sub.11, preferably C.sub.13 or greater. R may be
optionally substituted with substituents that do not interfere with
the detergent's function. M is preferably, calcium, magnesium, or
barium. More preferably, M is calcium.
[0072] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791 for
additional information on synthesis of these compounds. The metal
salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0073] Alkaline earth metal phosphates are also used as
detergents.
[0074] Detergents may be simple detergents or what is known as
hybrid or complex detergents. The latter detergents can provide the
properties of two detergents without the need to blend separate
materials. See U.S. Pat. No. 6,034,039 for example.
[0075] Preferred detergents include calcium phenates, calcium
sulfonates, calcium salicylates, magnesium phenates, magnesium
sulfonates, magnesium salicylates and other related components
(including borated detergents). Typically, the total detergent
concentration is about 0.01 to about 6.0 weight percent,
preferably, about 0.1 to 0.4 weight percent.
[0076] Pour Point Depressants
[0077] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
invention if desired. These pour point depressant may be added to
lubricating compositions of the present invention to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
polymethacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2.721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Each of these
references is incorporated herein in its entirety. Such additives
may be used in an amount of about 0.01 to 5 weight percent,
preferably about 0.01 to 1.5 weight percent.
[0078] Corrosion Inhibitors
[0079] Corrosion inhibitors are used to reduce the degradation of
metallic parts that are in contact with the lubricating oil
composition. Suitable corrosion inhibitors include thiadizoles.
See, for example, U.S. Pat. Nos. 2,719,125; 2,719,126; and
3,087,932, which are incorporated herein by reference in their
entirety. Such additives may be used in an amount of about 0.01 to
5 weight percent, preferably about 0.01 to 1.5 weight percent.
[0080] Seal Compatibility Additives
[0081] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Additives of this type are commercially
available. Such additives may be used in an amount of about 0.01 to
3 weight percent, preferably about 0.01 to 2 weight percent.
[0082] Anti-Foam Agents
[0083] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Anti-foam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 percent and
often less than 0.1 percent.
[0084] Inhibitors and Antirust Additives
[0085] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available; they are referred to also in Klamann, op.
cit.
[0086] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent.
[0087] Friction Modifiers
[0088] A friction modifier is any material or materials that can
alter the coefficient of friction of any lubricant or fluid
containing such material(s). Friction modifiers, also known as
friction reducers, or lubricity agents or oiliness agents, and
other such agents that change the coefficient of friction of
lubricant base oils, formulated lubricant compositions, or
functional fluids, may be effectively used in combination with the
base oils or lubricant compositions of the present invention if
desired. Friction modifiers that lower the coefficient of friction
are particularly advantageous in combination with the base oils and
lube compositions of this invention. Friction modifiers may include
metal-containing compounds or materials as well as ashless
compounds or materials, or mixtures thereof. Metal-containing
friction modifiers may include metal salts or metal-ligand
complexes where the metals may include alkali, alkaline earth, or
transition group metals. Such metal-containing friction modifiers
may also have low-ash characteristics. Transition metals may
include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include
hydrocarbyl derivative of alcohols, polyols, glycerols, partial
ester glycerols, thiols, carboxylates, carbamates, thiocarbamates,
dithiocarbamates, phosphates, thiophosphates, dithiophosphates,
amides, imides, amines, thiazoles, thiadiazoles, dithiazoles,
diazoles, triazoles, and other polar molecular functional groups
containing effective amounts of 0, N, S, or P, individually or in
combination. In particular, Mo-containing compounds can be
particularly effective such as for example Mo-dithiocarbamates,
Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am),
Mo-alcoholates, Mo-alcohol-amides, etc.
[0089] Ashless friction modifiers may have also include lubricant
materials that contain effective amounts of polar groups, for
example hydroxyl-containing hydrocaryl base oils, glycerides,
partial glycerides, glyceride derivatives, and the like. Polar
groups in friction modifiers may include hyrdocarbyl groups
containing effective amounts of 0, N, S, or P, individually or in
combination. Other friction modifiers that may be particularly
effective include, for example, salts (both ash-containing and
ashless derivatives) of fatty acids, fatty alcohols, fatty amides,
fatty esters, hydroxyl-containing carboxylates, and comparable
synthetic long-chain hydrocarbyl acids, alcohols, amides, esters,
hydroxy carboxylates, and the like. In some instances fatty organic
acids, fatty amines, and sulfurized fatty acids may be used as
suitable friction modifiers.
[0090] Useful concentrations of friction modifiers may range from
about 0.01 wt % to 10-15 wt % or more, often with a preferred range
of about 0.1 wt % to 5 wt %. Concentrations of molybdenum
containing materials are often described in terms of Mo metal
concentration. Advantageous concentrations of Mo may range from
about 10 ppm to 3000 ppm or more, and often with a preferred range
of about 20-2000 ppm, and in some instances a more preferred range
of about 30-1000 ppm. Friction modifiers of all types may be used
alone or in mixtures with the materials of this invention. Often
mixtures of two or more friction modifiers, or mixtures of friction
modifiers(s) with alternate surface active material(s), are also
desirable.
[0091] Typical Additive Amounts
[0092] When lubricating oil compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
invention are shown in the Table 1 below.
[0093] Note that many of the additives are shipped from the
manufacturer and used with a certain amount of base oil solvent in
the formulation. Accordingly, the weight amounts in the table
below, as well as other amounts mentioned in this patent, are
directed to the amount of active ingredient (that is the
non-solvent or non-diluent oil portion of the ingredient). The
weight percents indicated below are based on the total weight of
the lubricating oil composition.
2TABLE 1 Typical Amounts of Various Lubricant Oil Components
Approximate Weight Approximate Weight Compound Percent (Useful)
Percent (Preferred) Detergent 0.01-6 0.01-4 Dispersant 0.1-20 0.1-8
Friction Reducer 0.01-5 0.01-1.5 Viscosity Index Improver 0.0-40
0.01-30, more preferably 0.01 to 15 Antioxidant 0.01-5 0.01-1.5
Corrosion Inhibitor 0.01-5 0.01-1.5 Anti-wear Additive 0.01-6
0.01-4 Pour Point Depressant 0.0-5 0.01-1.5 Anti-foam Agent 0.001-3
0.001-0.15 Base Oil Balance balance
[0094] Experimental
[0095] The types and quantities of performance additives used in
combination with the instant invention in lubricant compositions
are not limited by the examples shown herein as illustrations.
[0096] Unless otherwise specified, kinematic viscosity at
40.degree. C. or 100.degree. C. is determined according to ASTM
test method D 445, viscosity index is determined by ASTM test
method D 2270, pour point is determined by ASTM test method D 97,
and TBN by ASTM test method number D 2896.
EXAMPLES 2.1-2.4
[0097] Lubricant Wear Performance
[0098] The wear properties of lubricant oils of differing
compositions are measured using Sequence IVA industry-approved
engine testing (ASTM Research Report RR:D02-1473) to evaluate wear
performance under severe conditions. The Sequence IVA (Nissan
KA24E) engine test measures the average wear at seven different
positions along the flank of 12 cam lobes. For each cam lobe, the
average wear at the seven locations are summed to determine the
individual lobe 7-point wear. Then the 7-point wear of all 12 lobes
are averaged and a final average 7-point cam lobe result is
reported in microns. Lower wear numbers are beneficial and
desirable. Oils with 7-point wear of <120.mu. meet the Sequence
IVA wear requirements of performance categories such as API SL and
ILSAC GF-3. Test results for this invention are shown in Table
2.
[0099] Each of the above oils tested contained approximately 7% of
hydrocarbyl aromatic comprising C.sub.16 monoalkylated naphthalene,
and is formulated with an additives package which includes
detergents, inhibitors, viscosity index improvers, defoamants,
supplementary dispersants, and the like.
[0100] Example 2.1 illustrates the Sequence IVA wear performance of
a high wear oil exhibiting 210 microns of wear and is formulated
with approximately 4.5% of a high molecular weight (derived from
approximately 2500 Mn polyisobutylene) borated bissuccinimide
dispersant, approximately 1.0% of an organic molybdenum compound
(not containing sulfur but made from molybdenum and
hydroxyl-containing nitrogen compounds), and approximately 0.5% of
an auxiliary heterocyclic sulfur source. The formulation of Example
1.1 also contains 0% ZDDP which is traditionally used as an
antiwear agent. This lubricant composition performs poorly on the
Sequence IVA test, resulting in 210 microns of wear.
[0101] Example 2.2 illustrates the Sequence IVA wear performance of
a high wear oil exhibiting 289 microns of wear and is formulated
with approximately 4.5% of a high molecular weight (derived from
approximately 2500 Mn polyisobutylene) borated bissuccinimide
dispersant and approximately 0.35% of a molybdenum (trimer)
dithiocarbamate. This formulation also contains 0% ZDDP which is
traditionally used as an antiwear agent. This lubricant composition
performs poorly on the Sequence IVA test, resulting in 289 microns
of wear.
[0102] Example 2.3 illustrates the Sequence IVA wear performance of
an exceptionally low wear oil and exhibits a surprisingly low 44
microns of wear, well below industry accepted standards. This
outstanding wear performance oil is formulated with approximately
7% of a moderate molecular (derived from approximately 1300 Mn
polyisobutylene) weight borated mono- and bissuccinimide
dispersant, and approximately 0.35% of a molybdenum (trimer)
dithiocarbamate. In addition, this oil contains 0% ZDDP and 0%
phosphorus. This lubricant composition performed surprisingly well
on the Sequence IVA test, resulting in only 44 microns of wear.
[0103] Example 2.4 illustrates the Sequence IVA wear performance of
a high wear oil exhibiting 134 microns of wear and is formulated
with approximately 7% of a moderate molecular (derived from
approximately 1300 Mn polyisobutylene) weight borated mono- and
bissuccinimide dispersant and no added molybdenum. This oil also
contains 0% ZDDP. This oil performs poorly on the Sequence IVA
test, resulting in 134 microns of wear.
[0104] Table la shows another aspect of this invention. It is
anticipated that wear benefits can be obtained for other
combinations of moderate molecular (derived from approximately 1300
Mn polyisobutylene) weight borated mono-and bissuccinimide
dispersant and molybdenum (trimer) dithiocarbamate combined with
some hydrocarbyl aromatic base stock. This invention can also
provide advantageous wear benefits both in hydroprocessed base
stocks and Group III base stocks. Concentration ranges where
benefits are expected range from 2 to 10% for the borated
dispersant, 0.1 to 2% for the molybdenum (trimer) dithiocarbamate
combined with hydrocarbyl aromatics ranging from 3% to 15%. These
embodiments can be advantageously used in both hydroprocessed base
stock (e.g., HDT A) and GpIII base stocks.
[0105] These above results clearly show the beneficial effect of
using moderate molecular weight borated mono- and bis-succinimide
dispersant and organic molybdenum compound. Additionally,
beneficial effects derive from the addition of low levels of
hydrocarbyl aromatic contained in the lubricants tested for wear
control in the above Sequence IVA tests. It is also significant to
note that excellent wear performance is obtained in the absence of
ZDDP or phosphorus. This indicates that this invention can also be
useful for engines that require low levels of phosphorus (e.g.,
about 0.05% or less) or even phosphorus-free lubricants to both
protect certain emissions catalysts and provide enhanced engine
performance. In addition, because ZDDP produces sulfated ash, the
additive combinations embodied in this invention can be even more
useful in engines that require reduced levels of sulfated ash in
lubricant oils in order to protect engine exhaust after treatment
devices.
3TABLE 2 Engine Wear Test Results Example: 2.1 2.2 2.3 2.4 High MW
borated bis-succinimide 4.5 4.5 0.0 0.0 Low MW borated mono &
bis-succinimide 0.0 0.0 7.0 7.0 Polybutenyl succinate ester/imide
mixture 2.5 2.5 0.0 0.0 Detergent/Dispersant/Inhibitor performance
8.8 8.8 8.8 8.8 package Dimercaptothiadiazole derivative 0.5 0.0
0.0 0.0 Organic molybdenum additive 1.0 0.0 0.0 0.0 Trimeric
molybdenum dithiocarbamate 0.0 0.35 0.35 0.0 4 cSt PAO Bal Bal Bal
Bal Hydrocarbyl aromatic 7 7 7 7 Blend Physical Properties
Phosphorous (calculated), ppm 0 0 0 0 Boron (calculated), ppm 104
104 665 665 Molybdenum (calculated), ppm 800 197 197 0.0 Engine
Wear Results 210 289 44 134 Nissan KA24E 7-Point Wear, .mu.
[0106] Lubricant compositions cited below are examples of the
instant invention, with such compositions not limiting the
invention.
4TABLE 3 Lubricant Compositions Example 3.1 3.2 3.3 3.4 3.5 3.6 3.7
3.8 Low MW borated mono 2 10 2 10 2 10 2 10 & bis-succinimide
Detergent/Dispersant/ 8.8 9.3 8.8 8.8 8.8 8.8 9.3 8.8 Inhibitor
performance package Trimeric molybdenum 0.1 0.1 1 1 0.1 0.1 1 1
dithiocarbamate Ester 5 150 N Group I Base Stock 5 Hydrocarbyl
aromatic 3 3 3 3 15 15 15 15 HDT A Bal Bal Bal Bal Bal Bal Bal Bal
Blend Physical Properties Phosphorous (calculated), 0 500 0 0 0 0
500 0 ppm Boron (calculated), ppm 180 950 180 950 180 950 180 950
Molybdenum (calculated), 56 56 560 560 56 56 560 560 ppm Component
3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 Low MW borated mono 2 10 2
10 2 10 2 10 & bis-succinimide Detergent/Dispersant/ 8.8 8.8
8.8 9.3 9.3 8.8 8.8 8.8 Inhibitor performance package Trimeric
molybdenum 0.1 0.1 1 1 0.1 0.1 1 1 dithiocarbamate Ester 2 150 N
Group I Base Stock 10 Hydrocarbyl aromatic 3 3 3 3 15 15 15 15
GpIII 4 Bal Bal Bal Bal Bal Bal Bal Bal Blend Physical Properties
Phosphorous (calculated), 0 0 0 500 500 0 0 0 ppm Boron
(calculated), 180 950 180 950 180 950 180 950 ppm Molybdenum
(calculated), 56 56 560 560 56 56 560 560 ppm
EXAMPLES 4.1-4.4
[0107] Lubricant Oxidation and Corrosion Performance
[0108] Synergistic combinations of borated mono- and
bis-succinimide dispersant and organic molybdenum compound improve
lubricant oxidation and corrosion performance. Catalytic oxidation
testing is performed using several groups of different components
as detailed in Table 4. The results exemplify the superior
properties of the compositions of the present invention. Various
physical tests are performed on the oils. ASTM test methods for
these are listed in Table 4.
[0109] The Catalytic Oxidation Test may be summarized as follows.
The test lubricant composition is subjected to a stream of air
which is bubbled through the composition at a rate of 5 liters per
hour. Present in the composition are metals commonly used as
materials of engine construction, namely:
[0110] (a) 15.6 sq. in. of sand-blasted iron wire,
[0111] (b) 0.78 sq. in. of polished copper wire.
[0112] (c) 0.87 sq. in. of polished aluminum wire, and
[0113] (d) 0.167 sq. in. of polished lead surface.
[0114] Lubricant performance is rated on the basis of prevention of
oil deterioration as measured by the increase in acid formation or
neutralization number (NN) and kinematic viscosity (KV) occasioned
by the oxidation. The sludge formation during the oxidation is
estimated visually.
[0115] In Example 4.1, approximately 8% of a moderate molecular
weight (derived from approximately 1300 Mn polyisobutylene) borated
mono- and bissuccinimide dispersant and approximately 0.17% of
molybdenum (trimeric) dithiocarbamate is evaluated with
approximately 0.2% mixed zinc dialkyl dithiophosphates (ZDDP) in a
polyalphaolefin oil (PAO) derived from olefins comprising 1-decene
and comprising an additional approximately 7% of hydrocarbyl
aromatic fluid ("alkylated aromatic", primarily C.sub.16
monoalkylated naphthalene). This oil performs outstandingly well,
yielding an end of test viscosity increase of approximately 8.1%,
and an exceptionally good and low lead loss of approximately
0.8-mg, with no (nil) sludge. This oil performs exceedingly well in
high-temperature oxidative applications where wear metals or
bearing metals can accelerate deleterious effects of oxidation.
[0116] In Example 4.2, approximately 8% of a moderate molecular
weight (derived from approximately 1300 Mn polyisobutylene) borated
mono- and bissuccinimide dispersant is evaluated with approximately
0.2% secondary zinc dialkyl dithiophosphates in a polyalphaolefin
oil derived from olefins comprising 1-decene and comprising an
additional approximately 7% of hydrocarbyl aromatic fluid
(primarily C.sub.16 monoalkylated naphthalene). This oil performed
poorly, yielding an end of test viscosity increase of approximately
28.8%, and giving an exceptionally poor and high lead loss of
approximately 31.5-mg, with a trace of sludge.
[0117] In Example 4.3, approximately 8% of a relatively high
molecular weight (derived from approximately 2300 Mn
polyisobutylene) non-borated bissuccinimide dispersant and
approximately 0.17% of molybdenum (trimeric) dithiocarbamate is
evaluated with approximately 0.2% secondary zinc dialkyl
dithiophosphates in a polyalphaolefin oil derived from olefins
comprising 1-decene and comprising an additional approximately 7%
of hydrocarbyl aromatic fluid (primarily C 16 monoalkylated
naphthalene). This oil performed poorly, yielding an end of test
exceptionally poor and high lead loss of approximately 21.3 mg,
with light of sludge.
[0118] Table 5 shows lubricant compositions which are expected to
demonstrate the performance benefits of this invention. It is
anticipated that oxidation, sludge control, and corrosion control
benefits can be obtained for other combinations of moderate
molecular (derived from approximately 1300 Mn polyisobutylene)
weight borated mono- and bissuccinimide dispersant, molybdenum
(trimer) dithiocarbamate, and ZDDP combined with some hydrocarbyl
aromatic base stock. This invention can provide oxidation, sludge
control, and corrosion control benefits both in hydroprocessed base
stocks (e.g., HDT A) and Group III base stocks. Concentration
ranges where benefits are expected range from 2 to 10% for the
borated dispersant, 0.1 to 1% for the molybdenum (trimer)
dithiocarbamate, 0 to 1% ZDDP combined with hydrocarbyl aromatics
ranging from 3% to 15%. These combinations can work in both
hydroprocessed (e.g., HDT A) base stocks and Group III (GpIII) base
stocks.
[0119] These results clearly demonstrate the synergism provided by
the moderate molecular weight (derived from approximately 1300 Mn
polyisobutylene) borated mono- and bissuccinimide dispersant and
organic molybdenum compound [molybdenum (trimeric)
dithiocarbamate]. It is also significant to note that excellent
oxidation, sludge control, and corrosion performance is obtained in
formulations containing low levels of ZDDP or phosphorus. This
indicates that this invention can also be useful for engines that
require low levels of phosphorus (e.g., about 0.05% or less)
lubricants to both protect certain emissions catalysts and provide
enhanced engine performance. In addition, since ZDDP produces
sulfated ash, the anti-oxidation, sludge control, corrosion control
system described in this invention would also be useful in engines
that required reduced sulfated ash oils to protect after treatment
devices.
5TABLE 4 Catalytic Oxidation Testing Results Test Example: Method
4.1 4.2 4.3 PAO 84.6 84.8 84.6 2.degree. ZDDP 0.2 0.2 0.2 Alkylated
Aromatic 7.0 7.0 7.0 Low MW borated mono & bis- 8.0 8.0 0.0
succinimide High MW polyisobutyl bis- 0.0 0.0 8.0 succinimide
Trimeric molybdenum 0.17 0.0 0.17 dithiocarbamate Property
Kinematic Viscosity at D 445 5.4 5.4 5.4 100.degree. C. KV at
100.degree. C. after B10 D 455 5.9 7.0 5.0 Oxidation Viscosity
Increase, % 8.1 28.8 9.2 Acid Number D 664 2.66 2.64 4.68 RBOT, min
D 2272 248 276 318 Catalytic Oxidation Test, Nil Trace Light Sludge
Catalytic Oxidation Test, 0.8 31.5 21.3 Lead Loss, %
[0120]
6TABLE 5 Other Illustrations Offering Oxidation, Sludge Control,
and Corrosion Benefits 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 GpIII 4 Bal
Bal Bal PAO 4 Bal Bal HDT A Bal Bal Bal Ester 8 2 10 3 150 N Grp I
15 Dispersant/ 14 14 14 7 7 7 14 14 Detergent/ Inhibitor Additive
Performance Package 2.degree. ZDDP 0 1 0 1 0 1 0 1 Alkylated 3 3 15
15 15 3 15 15 Aromatic Low MW 2 2 2 2 10 10 10 10 borated mono
& bis- succinimide Trimeric 1.0 0.1 0.1 1.0 1.0 0.1 0.1 1.0
molybdenum dithio- carbamate
[0121] Table 6 provides a listing of typical properties of base
stocks used in formulating the oils shown in examples 2.1 through
5.8.
7TABLE 6 Typical Properties of Base Stocks Used in Examples
Hydrocarbyl PAO * Aromatic 4 HDT A GpIII 4 Ester 150 N D 445
Kinematic 29.3 18 22.65 15.6 32 Viscosity at 40.degree. C., cSt D
445 Kinematic 4.7 4 4.55 3.8 5.2 5.2 Viscosity at 100.degree. C.,
cSt D2272 Viscosity Index 75 120 116 138 131 97 D1500 ASTM Color
1.0 0 L0.5 0 0 D2007 Saturates, wt % na 100 97 na na 80 D2622
Sulfur, ppm 150 0 60 0 0 200 API Group V IV II III V I
[0122] All U.S. Patents cited in this application are hereby
incorporated in their entirety by reference.
* * * * *
References