U.S. patent application number 10/320141 was filed with the patent office on 2003-08-21 for lubricating oil compositions.
Invention is credited to Baillargeon, David J., Buck, William H., Deckman, Douglas Edward, Maxwell, William L., Winemiller, Mark D..
Application Number | 20030158055 10/320141 |
Document ID | / |
Family ID | 27737287 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030158055 |
Kind Code |
A1 |
Deckman, Douglas Edward ; et
al. |
August 21, 2003 |
Lubricating oil compositions
Abstract
The present invention provides a viscosity index improving
lubricant additive which comprises an olefinic oligomer of about
2,000 to about 20,000 number average molecular weight having a
viscosity of 75 to about 3,000 cSt at 100.degree. C. and a
hydrocarbyl aromatic which contains at least about 5% of its weight
from aromatic moieties having a viscosity of about 3 to about 50
cSt at 100.degree. C. where the weight ratio of hydrocarbyl
aromatic component to olefin oligomer is from about 1:2 to about
50:1. In another aspect, the invention provides for a lubricating
oil composition comprising a base oil and the instant viscosity
index improving additive.
Inventors: |
Deckman, Douglas Edward;
(Mullica Hill, NJ) ; Maxwell, William L.;
(Pilesgrove, NJ) ; Buck, William H.; (West
Chester, PA) ; 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: |
27737287 |
Appl. No.: |
10/320141 |
Filed: |
December 16, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60353771 |
Jan 31, 2002 |
|
|
|
Current U.S.
Class: |
508/571 ; 208/19;
508/581 |
Current CPC
Class: |
C10M 2207/025 20130101;
C10M 2207/024 20130101; C10N 2020/02 20130101; C10M 2205/022
20130101; C10M 2207/023 20130101; C10M 2203/06 20130101; C10M
2205/028 20130101; C10M 161/00 20130101 |
Class at
Publication: |
508/571 ;
508/581; 208/19 |
International
Class: |
C10M 127/02; C10M
127/04; C10M 129/16; C10M 135/28 |
Claims
What is claimed is:
1. Lubricant additive comprising: (a) a hydrocarbyl aromatic which
contains at least about 5% of its weight from aromatic moieties and
having a viscosity of about 3 to about 50 cSt at 100.degree. C.;
(b) an olefinic oligomer of about 2,000 to about 20,000 number
average molecular weight and having a viscosity of about 75 to
about 3,000 cSt at 100.degree. C.; and wherein the weight ratio of
component (a) to component (b) is from about 1:2 to about 50:1.
2. The lubricant additive of claim 1 wherein the olefinic oligomer
is an alpha olefin.
3. The lubricant additive of claim 2 wherein the alpha olefin has a
viscosity of about 100 to about 1,500 cSt at 100.degree. C.
4. The lubricant additive of claim 3 wherein the hydrocarbyl
aromatic has a viscosity of about 3.4 to about 20 cSt at
100.degree. C.
5. The lubricant additive of claim 4 wherein the ratio of component
(a) to component (b) is from about 1.5:1 to about 10:1.
6. The lubricant additive of claim 5 wherein the alpha olefin is
derived from decene, dodecene, tetradecene, or octane.
7. The lubricant additive of claim 6 wherein the hydrocarbyl
aromatic contains an aromatic moiety of the group consisting of:
alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl
naphthols, alkyl diphenyl sulfides, and alkylated bis-phenol A
wherein the alkylated aromatic can be mono-alkylated, dialkylated
or polyalkylated.
8. The lubricant additive of claim 7 wherein the alpha olefin has a
viscosity of about 100 to about 1,000 cSt at 100.degree. C.
9. A lubricating oil composition comprising: (a) an oil of
lubricating viscosity selected from the group consisting of Group
II base stock, Group III base stock, Group IV base stock, and wax
isomerates, and mixtures thereof; and (b) the lubricant additive of
claim 1 in an amount of about 3% to about 40% of the weight of the
lubrication oil composition.
10. A lubricating oil composition comprising: (a) an oil of
lubricating viscosity selected from the group consisting of Group
II base stock, Group III base stock, Group IV base stock, and wax
isomerates, and mixtures thereof; and (b) the lubricant additive of
claim 2 in an amount of about 3 to about 40% of the weight of the
lubrication oil composition.
11. A lubricating oil composition comprising: (a) an oil of
lubricating viscosity selected from the group consisting of Group
II base stock, Group III base stock, Group IV base stock, and wax
isomerates, and mixtures thereof; and (b) the lubricant additive of
claim 8 in an amount of about 3 to about 40% of the weight of the
lubrication oil composition.
12. The lubricating oil composition of any one of claims 9-11
wherein the oil of lubricating viscosity contains at least 50
weight percent of at least one of Group II base stock, Group III
base stocks, Group IV base stock, and wax isomerates, and mixtures
thereof.
13. The lubricating oil composition of claim 12 wherein the amount
of Group II base stock, Group III base stocks and wax isomerate
base stock is at least 20 weight percent of the lubricating oil
composition.
14. The lubricating oil composition of claim 13 wherein the amount
of Group II base stock, Group III base stocks and wax isomerate
base stock is at least 30 weight percent of the lubricating oil
composition.
15. The lubricating oil composition of claim 14 wherein the amount
of Group II base stock, Group III base stocks and wax isomerate
base stock is at least 50 weight percent of the lubricating oil
composition.
16. A method of obtaining viscosity index enhancement in a
lubrication composition comprising the step of adding the following
to the lubricating composition: (i) a hydrocarbyl aromatic which
contains at least about 5% of its weight from aromatic moieties and
having a viscosity of about 3 to about 50 cSt at 100.degree. C.;
and (ii) an olefinic oligomer of about 2,000 to about 20,000 number
average molecular weight and having a viscosity of about 75 to
about 3,000 cSt at 100.degree. C.; wherein the weight ratio of
component (a) to component (b) is from about 1:2 to about 50:
1.
17. A method of obtaining enhanced high-temperature high-shear
(HTHS) viscosity performance of a lubricating composition
comprising the step of adding the following to the lubricating
composition: (i) a hydrocarbyl aromatic which contains at least
about 5% of its weight from aromatic moieties and having a
viscosity of about 3 to about 50 cSt at 100.degree. C.; and (ii) an
olefinic oligomer of about 2,000 to about 20,000 number average
molecular weight and having a viscosity of about 75 to about 3,000
cSt at 100.degree. C.; wherein the weight ratio of component (a) to
component (b) is from about 1:2 to about 50:1.
18. A method of making lubricant composition rheological properties
more Newtonian comprising the step of adding the following to the
lubricating composition: (i) a hydrocarbyl aromatic which contains
at least about 5% of its weight from aromatic moieties and having a
viscosity of about 3 to about 50 cSt at 100.degree. C.; and (ii) an
olefinic oligomer of about 2,000 to about 20,000 number average
molecular weight and having a viscosity of about 75 to about 3,000
cSt at 100.degree. C.; wherein the weight ratio of component (a) to
component (b) is from about 1:2 to about 50:1.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application 60/353,771 filed Jan. 31, 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to lubricating oil compositions
suitable for use in internal combustion engines.
[0004] 2. Background
[0005] Contemporary lubricants such as engine oils use mixtures of
additives such as dispersants, detergents, inhibitors, viscosity
index improvers and the like to provide engine cleanliness and
durability under a wide range of performance conditions of
temperature, pressure, and lubricant service life.
[0006] It is critical to maintain sufficiently high viscosity at
high operating temperatures to maintain a minimum lubricant film to
minimize component wear. It is also critical to maintain a low,
low-temperature viscosity to prevent excessive low-temperature oil
thickening and to provide for satisfactory low-temperature
operation. Viscosity index improvement can be a measure of such
high- and low-temperature performance.
[0007] A variety of polymeric viscosity index improving components
are used in various lubricating fluids to provide the necessary
cross-grading to maintain fluid durability at high temperatures and
to provide low viscosity at low temperatures to enhance
low-temperature starting and low-temperature operation engine
operation. These materials include high molecular weight
hydrocarbons, polyesters aid viscosity index improver dispersants
that function as both a viscosity index improver and a dispersant.
In particular, compositions such as styrene-diene copolymers,
polymethacrylates, radial isoprene polymers, mixed olefin
copolymers such as those chosen from the group consisting of
ethylene-propylene copolymers and functionalized derivatives
thereof are known. Many of the polymeric components used in the
past have had deficiencies associated with the chemistry of the
polymers such as shear instability and cleanliness properties.
Additionally, the response of some of these added components are
not as desirable as required for critical high performance
considerations. Thus, there is a need for improved viscosity index
improving materials.
SUMMARY OF THE INVENTION
[0008] The present invention provides a viscosity index enhancing
lubricant additive which comprises an olefin oligomer of about
2,000 to about 20,000 number average molecular weight and a
viscosity of about 75 to about 3,000 cSt at 100.degree. C. and a
hydrocarbyl aromatic which contains at least about 5% of its weight
from aromatic moieties and a viscosity of about 3 to about 50 cSt
at 100.degree. C. where the weight ratio of hydrocarbyl aromatic
component to olefin oligomer is from about 1:2 to about 50:1. In
another aspect, the invention provides for a lubricating oil
composition comprising a base oil and the instant viscosity index
enhancing additive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a plot of the viscosity index enhancement for
viscosity index enhancing compositions with differing ratios of
olefin oligomer and other hydrocarbon base stock.
DETAILED DESCRIPTION OF THE INVENTION
[0010] 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, anti-corrosion, 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
nominal blending or use conditions.
[0011] In a first aspect the invention relates to a viscosity index
improver additive composition. Viscosity index improvers (also
known as VI improvers, viscosity modifiers, and viscosity
improvers) provide lubricants with high and low-temperature
operability. These additives impart favorable viscosity index
number enhancement and shear stability at elevated temperatures and
acceptable viscosity at low temperatures.
[0012] The viscosity index improver additives of the present
invention are mixtures of olefin oligomers and hydrocarbyl
aromatics. It is found that within narrow concentration ranges, a
significant viscosity index enhancement occurs. In particular, a
synergistic effect on Viscosity Index enhancement is seen for a
ratio of approximately 1:1 to approximately 20:1 of hydrocarbyl
aromatic(s): olefin oligomer. More preferred, depending upon
application and the presence or absence of other components, is a
ratio of about 1:1 to about 10:1. A ratio of 1:1.5 to about 10:1 is
preferred depending upon the application. Depending upon other
components, and performance needs, ratios of about 1:2 to a 50:1
could be more advantageously used.
[0013] Another aspect of this invention is a means to provide an
unexpected increase in high-temperature high-shear (HTHS) viscosity
when combining hydrocarbyl aromatics with olefin oligomers. An
olefin oligomer is combined separately with a hydrocarbyl aromatic
base stock, a 4 cSt PAO base stock, and a hydroprocessed base stock
in a series of ratios. Kinematic viscosity (KV, as determined by
ASTM D 445) at 40.degree. C. and 100.degree. C., HTHS viscosity
(ASTM D 4683) at 150.degree. C. and density at 150.degree. C. (ASTM
D 4052) are measured for all mixtures. The measured HTHS viscosity
is compared to the predicted HTHS viscosity. Predicted HTHS
viscosity is determined by extrapolating the KV at 40.degree. C.
and KV at 100.degree. C. viscosity measurements for a sample to
150.degree. C. per ASTM D 341 and multiplying this result by the
sample density at 150.degree. C. The HTHS enhancement is then
determined by subtracting the predicted HTHS viscosity from the
measured HTHS viscosity. For mixtures containing hydrocarbyl
aromatics and the olefin oligomer, there is an unexpected and
significant HTHS enhancement. The HTHS enhancement for the
hydrocarbyl aromatic/olefin oligomer mixtures is greater than that
observed for the mixtures of olefin oligomer with either 4 cSt PAO
or hydroprocessed base stock. This indicates that there is a
synergy when hydrocarbyl aromatics are combined with olefin
oligomers.
[0014] Another aspect of this invention is that when the olefin
oligomer is added to hydrocarbyl aromatics, PAO, or hydroprocessed
base stock, the resulting mixture surprisingly has Newtonian
high-temperature and low-temperature viscometric properties,
providing significant additional potential performance
characteristics to the instant invention.
[0015] The hydrocarbyl aromatics that can be used can be any
hydrocarbyl molecule that contains preferably at least about 5% of
its weight derived from an aromatic moiety such as a benzenoid
moiety or naphthenoid moiety, or their derivatives. This can
include hydrocarbyl aromatics such as alkyl benzenes, alkyl
naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl
phenols, alkyl diphenyl sulfides, alkylated bis-phenol A, and the
like. The aromatic can be mono-alkylated, dialkylated,
polyalkylated, and the like. As further examples, alkylbenzenes
(dodecylbenzenles, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes, for example); polyphenyls (biphenyls,
terphenyls, alkylated polyphenyls, for example); alkylated
naphthalene (C.sub.16 alkyl naphthalene, for example); alkylated
diphenyl ethers; and alkylated diphenyl sulfides and the
derivatives, analogs, and homologs thereof and the like.
Functionalization can thus be as mono- or poly-functionalized. As
examples above show, the aromatic group can contain non-hydrocarbon
material, thus the term "hydrocarbyl" in "hydrocarbyl aromatic"
refers only to the substituent. The hydrocarbyl groups can also be
comprised of mixtures of alkyl groups, alkenyl groups, alkynyl,
cycloalkyl groups, cycloalkenyl groups and other related
hydrocarbyl groups, and can optionally also contain S, N, and/or O.
Typically the hydrocarbyl group is a long chain alkyl group with
about 8 or more carbons, typically containing about 14 or more
carbons, with about 16 or more carbons on occasion being more
preferred. Viscosities at 100.degree. C. of approximately 3 cSt to
about 50 cSt are often desirable, with viscosities of approximately
3.4 cSt to about 20 cSt often being preferred.
[0016] Alkylated aromatics such as the hydrocarbyl aromatics of the
present invention may be produced by well-known Friedel-Crafts
alkylation of aromatic compounds. See Friedel-Crafts and Related
Reactions, Olah, G. A. (ed), Inter-science Publishers, New York,
1963. For example, an aromatic compound, such as benzene or
naphthalene, is alkylated by an olefin, alkyl halide or alcohol in
the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and
Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See
Olah, G. A. (ed), Inter-science Publishers, New York, 1964. Many
homogeneous or heterogeneous, solid catalysts are known to one
skilled in the art. The choice of catalyst depends on the
reactivity of the starting materials and product quality
requirements. For example, strong acids such as AlCl.sub.3,
BF.sub.3, or HF may be used. In some cases, milder catalysts such
as FeCl.sub.3 or SnCl.sub.4 are preferred. Newer alkylation
technology uses zeolites or solid super acids.
[0017] Certain combinations of alkylated aromatics and PAOs are
described in U.S. Pat. No. 5,602,086.
[0018] The high viscosity olefin oligomer can be derived from
alpha-olefins such as octene, decene, dodecene, tetradecene,
lexadecene and the like, alone or as mixtures of these and other
olefins. The oligomer should be oligomerized to form molecular
weight components, as measured by number average molecular weight
of at least 2,000 up to about a number average molecular weight of
approximately 20,000. More preferably, a number average molecular
weight of approximately 2,500 to about 10,000 can be more
preferred. At times, a number average molecular weight range of
2,500 to about 7,000 can be most preferred. A fluid having a
viscosity at 100.degree. C. of approximately 75 to 3,000 cSt is
desirable, with 100 to about 1,500 cSt often being preferred, with
about 100 to 1,000 cSt being more preferred. Mw ranges of
approximately 4,000 to approximately 50,000 or more can be used to
advantage. Typical high viscosity olefin oligomers have Mw/Mn
ranges of approximately 1.1 to about 5 or more, with ranges of 1.5
to about 4 often preferred, with ranges of about 1.7 to about 3
often most preferred, depending upon the lubricant into which is
formulated along with a hydrocarbyl aromatic.
[0019] In another aspect, the present invention concerns a
lubricating oil composition containing the present viscosity index
enhancing composition. The viscosity index enhancing composition of
this invention can advantageously be used at a total concentration
of about 3% to about 40% in a paraffinic lubricating oil base stock
or a mixture of lubricating oil base stocks having a combined
viscosity index of approximately 110 or greater. Concentrations of
such synergistic components can more preferably range from
approximately 5% to about 20%, or more preferably from about 6% to
about 18% by weight. Group II and/or Group III hydroprocessed or
hydrocracked base stocks and similar base stocks such as those
described herein when used in lubricants comprised of such
synergistic viscosity index enhancing components are greatly
preferred over polyalphaolefin lubricating base stocks when used in
conjunction with the components of this invention. At least 20% of
the total composition should consist of such Group II or Group III
base stocks, with 30%, on occasion being more preferable, and 48%
on occasion being even more preferable. Wax-derived
hydroisomerized-type base oils, such as wax-isomerate and
gas-to-liquid base stocks, can also be preferentially used with the
components of this invention. We believe that the improvement and
benefit is best when the components of this invention are added to
lubricating systems comprised of primarily Group II and or Group
III base stocks rather than when added to fluids comprised
primarily of synthetic fluids such as those derived using decene,
dodecene and or tetradecene trimers and tetramers fluids.
[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. Animal and vegetable
oils possessing favorable thermal oxidative stability can be used.
Of the natural oils, mineral oils can be 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, ethylene-alphaolefin compolymers, 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 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 available in viscosities up to about 100 cSt
(100.degree. C.). The PAOs typically comprise relatively low
molecular weight hydrogenated polymers or oligomers of alphaolefins
which include, but are not limited to, about C.sub.2 to about
C.sub.32 alphaolefin with about C.sub.8 to about C.sub.16
alphaolefins, such as 1-octene, 1-decene, 1-dodecene, mixtures
thereof, and the like being preferred. The preferred
polyalphaolefins are poly-1-octene, poly-1-decene, poly-1-dodecene,
mixtures thereof, and mixed olefin derived polyolefins, although
the dimers of higher olefins in the range of about C.sub.14 to
C.sub.18 may be used to provide low viscosity base stocks of
acceptably low volatility. The PAOs generally have a viscosity in
the range of from about 1.5 to 12 cSt at 100.degree. C. and are
generally predominantly trimers and tetramers of the starting
olefins, with lesser amounts of higher oligomers also present.
[0025] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as 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. Each of the afore mentioned
patents is incorporated by reference herein in its entirety.
[0026] Other useful synthetic lubricating base stock oils may also
be utilized, for example those described in the seminal work
"Synthetic Lubricants", Gunderson and Halt, Reinhold Publ. Corp.,
New York 1962 which is incorporated herein in its entirety.
[0027] In alkylated aromatic stocks, the alkyl substituents
typically are alkyl groups having from about 8 to 25 carbon atoms,
and preferably from about 10 to 18 carbon atoms. Any number of such
substituents may be present, although no more than 3 such groups
generally are preferred. See, for example, 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. 168 534 and U.S. Pat. No. 4,658,072. Alkylbenzenes
have been used as lubricant base stocks, 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., as well as 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 are described in "Synthetic Lubricants
and High Performance Functional Fluids", Dressler, H., chap 5, (R.
L. Shubkin (Ed.)), Marcel Dekker, N.Y. 1993. Each of the afore
noted disclosures is incorporated by reference herein in its
entirety.
[0028] Other useful lubricant oil base stocks include
Gas-to-Liquids (GTL) base stocks, comprised of hydroisomerized
Fischer-Tropsch waxes, and other wax-derived hydroisomerized (wax
isomerate) base oils. 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, incorporated herein in its entirety by
reference. 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, also incorporated herein by reference.
Particularly favorable processes are described in European Patent
Application Nos. 464546 and 464547, also incorporated herein.
Processes using Fischer-Tropsch wax feeds are described in U.S.
Pat. No. 4,594,172 and 4,943,672, incorporated herein by reference
in its entirety. 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 to cSt to
about 30 cSt, more preferably about 3.5 cSt to about 25 cSt, as
exemplified by GTL4 with kinematic viscosity of about 3.8 cSt at
100.degree. C. and a viscosity index of about 138. 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. In another aspect,
Gas-to-Liquids (GTL) base oils have advantageously low NOACK
volatility, and in combination with the instant invention can
provide additional advantages in lubricant compositions.
[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 swell characteristics may be secured by the use of esters such
as the esters of dibasic acids with monoalkanols and the polyol
esters of monocarboxylic 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, and the like, with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, and the like. 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 and
dieicosyl sebacate.
[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, trimetlhylol ethane, 2-methyl-2-propyl-1,3-propaniediol,
trimetlhylol propane, pentaerythritol and dipentaerythritol with
alkanoic acids containing at least about 4 carbon atoms (for
example, C.sub.5 to C.sub.30 acids such as saturated straight chain
fatty acids which include 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 of any such
components).
[0033] Preferred synthetic ester components are the esters of
trimethylol propane, trimethylol butane, trimetlhylol ethane,
pentaerythritol and/or-dipentaerythritol with one or more
monocarboxylic acids containing from about 5 to about 10 carbon
atoms. Such esters, including for example, Mobil P-41 and P-51
esters are available from 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-methylhexyl) 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,
their derivatives, and the like.
[0037] Although the benefit of the viscosity index improver may be
optimal when the improver is added to an engine oil comprising
primarily Group II and/or Group III base stocks or wax isomerate
base stock, lower concentrations of co-base stocks can also
advantageously be combined with the viscosity index improvers of
the invention. These co-base stocks, as described above, include
dibasic acid esters, polyol esters, other hydrocarbon oils, and the
like. These co-base stocks can also include Group IV synthetic
fluids (such as alphaolefin-derived trimers and tetramers) and also
Group I base stocks, provided that the engine oil comprises at
least about 50%, by weight, of Group II and/or Group III type base
stocks or wax isomerate base stocks.
[0038] Other Lubricating Oil Components
[0039] The instant invention can be used with 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, chomophoric
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 gives a good discussion of a number of the lubricant
additives discussed mentioned below. Reference is also made
"Lubricant Additives" by M. W. Ramey, published by Noyes Data
Corporation of Parkridge, N.J. (1973). Antiwear and EP
Additives
[0040] Internal combustion engine lubricating oils require the
presence of antiwear and/or extreme pressure (EP) additives in
order to provide adequate antiwear protection for the engine.
Increasingly demanding specifications for engine oil performance
have required increasing antiwear properties of the oil. Antiwear
and EP additives perform this role by reducing friction and wear of
metal parts.
[0041] While there are many different types of antiwear additives,
for several decades the principal antiwear additive for internal
combustion engine crankcase oils has been a metal
alkylthiophosphate and more particularly a metal
dialkyldithiophosphate in which the primary metal constituent is
zinc, or zinc dialkyldithiophosphate (ZDDP). Popular ZDDP compounds
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, including mixtures of such groups.
These alkyl groups may be straight chain or branched, and derived
from primary and/or secondary alcohols and/or alkaryl groups such
as alkyl phenol. The ZDDP typically is used in amounts of from
about 0.2 to 2 weight %, preferably from about 0.5 to 1.5 weight %,
more preferably from about 0.7 to 1.4 wt. % of the total lube oil
composition, although more or less can often be used.
[0042] However, it has been 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.
[0043] A variety of non-phosphorous additives are also useful as
antiwear and EP additives, including for example, sulfurized
olefins. Sulfur-containing olefins can be prepared by sulfurization
of various organic materials including aliphatic, arylaliphatic or
alicyclic olefin hydrocarbons containing from about 3 to 30 carbon
atoms, preferably from about 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
[0044] 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 herein by reference in its entirety.
[0045] 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 additive 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. Nos. 4,501,678, 4,758,362 discloses use of a
carbamate additive to provide improved anitiwear and extreme
pressure properties. The use of thiocarbamate as an antiwear
additive is disclosed in U.S. Pat. No. 5,693,598.
Thiocarbamate/molybdenuim complexes such as moly-sulfur alkyl
dithiocarbamate trimer complex (R.dbd.C.sub.8-C.sub.18 alkyl) are
also useful antiwear agents. Each of the aforementioned patents is
incorporated by reference herein in its entirety.
[0046] Esters of glycerol may be used as antiwear agents. For
example, mono-, di, and tri-oleates, mono-palmitates and
mono-myristates may be used.
[0047] ZDDP has been combined with other compositions that provide
anitiwear properties. U.S. Pat. No. 5,034,141 discloses that a
combination of a thiodixanthogen compound (octylthiodixanithogen,
for example) and a metal thiophosphate (ZDDP, for example) can
improve anti wear 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.
[0048] Preferred antiwear additives include phosphorus and sulfur
compounds such as zinc dithiophosphates and/or sulfur, nitrogen,
boron, molybdenum phosphorodithioates, molybdenum dithiocarbamates
and various organo-molybdenum derivatives including heterocyclics
(for example, dimercaptothiadiazoles, mercaptobenzothiadiazoles,
triazines, and the like), alicyclics, amines, alcohols, esters,
diols, triols, fatty amides and the like can also be used.
[0049] Such additive may be used in amounts ranging from about 0.01
to 6 weight %, preferably about 0.0 1 to 4 weight %.
[0050] Antioxidants
[0051] 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,
for example, Klamann op cite, and U.S. Pat. Nos. 4,798,684 and
5,084,197, incorporated herein by reference in their entirety,
[0052] 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 antioxidants are hindered phenolics that 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 hindered phenols substituted with about
C.sub.6+ alkyl groups and alkylene coupled derivatives of such
hindered phenols. Examples of phenolic materials of this type
include 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
mono-phenolic antioxidants may include, for example,
2,6-di-alkyl-phenolic proprionic ester derivatives. Bis-phenolic
antioxidants may also be advantageously used in combination with
the 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).
[0053] 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.11 S(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 about 6 to 12
carbon atoms. The aliphatic group is saturated. 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.
[0054] 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 call also be used.
Particular examples of aromatic amine antioxidants useful in the
present invention include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthy- lamine; phenyl-alplhanaphthylamine;
and p-octylphenyl-alpha-naphthylamine.
[0055] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants. Low sulfur peroxide
decomposers are useful as antioxidants.
[0056] 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 dithiocarbamates, 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.
[0057] 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.
[0058] Such additives may be used in amounts of from about 0.01 to
5 weight %, preferably from about 0.01 to 2 weight %, even more
preferably from about 0.01 to 1 weight %.
[0059] Detergents
[0060] 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.
[0061] 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.
[0062] it is generally 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.
[0063] Preferred detergents include the alkali or alkaline earth
metal salts of sulfates, phenates, carboxylates, phosphates, and
salicylates.
[0064] 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
chlorolnaphthalene, 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.
[0065] Ranney in "Lubricant Additives " op cit discloses a number
of overbased metal salts of various sulfonic acids which are useful
as detergents/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.
[0066] Alkaline 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
about C.sub.1-C.sub.30 alkyl groups, preferably about
C.sub.4-C.sub.20. Examples of suitable phenols include
isobutylphenol, 2-ethylhexylphenol, nonylphenol,
1-ethyldecylplhenol, and the like. It should be noted that starting
alkylphelnols 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 or sulfur halides, such as sulfur dichloride and
the like, and then reacting the sulfurized phenol with an alkaline
earth metal base.
[0067] 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
[0068] 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. R may be optionally substituted with
substituents that do not interfere with the detergent's function. M
is preferably, calcium, magnesium, or barium, and more preferably,
calcium and/or magnesium. Preferred are alkyl chains of at least
about C.sub.11, preferably about C.sub.13 or greater.
[0069] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791,
incorporated herein by reference in its entirety, 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.
[0070] Alkaline earth metal phosphates are also used as
detergents.
[0071] 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, for example, U.S. Pat. No. 6,034,039 incorporated
herein by reference in its entirety.
[0072] Preferred detergents include calcium phenates, calcium
sulfonates, calcium salicylates, magnesium phenates, magnesium
sulfonates, magnesium salicylates and other related components
(including borated detergents).
[0073] Typically the total detergent concentration is from about
0.01 to 6 weight %, preferably from about 0.1 to 3 weight %, even
more preferably from about 0.01 to 0.5 weight %.
[0074] Dispersant
[0075] 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. Preferably, the dispersant is
ashless. So called ashless dispersants are organic materials that
form substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents
discussed above form ash upon combustion.
[0076] Suitable dispersants typically contain a polar group
attached to a relatively high molecular weight hydrocarbon chain.
The polar group typically contains at least one element of
nitrogen, oxygen, or phosphorous. Typical hydrocarbon chains
contain about 50 to 400 carbon atoms.
[0077] Dispersants include phenates, sulfonates, sulfurized
phenates, salicylates, naphthenates, stearates, carbamates,
thiocarbamates, and phosphorus derivatives. A particularly useful
class of dispersants are 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 polyisobutylene group. Many
examples of this type of dispersant are well known. Exemplary U.S.
patents describing such dispersants include 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. 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 is also found in European Patent Application No. 471
071. Each of the above noted patents and patent applications is
incorporated herein by reference in its entirety.
[0078] Hydrocarbyl-substituted succinic acid compounds are well
known dispersants. In particular, succinimide, succiniate esters,
or succiniate ester amides prepared by the reaction of
hydrocarbon-substituted succinic acid preferably having at least 50
carbon atoms in the hydrocarbon substituent, with at least one
equivalent of an alkylene amine, are particularly useful.
[0079] Succinimides are formed by the condensation reaction between
alkenyl succinic anhydrides and amines. Molar ratios can vary
depending on the polyamine. For example, the molar ratio of alkenyl
succinic anhydride to TEPA can vary from about 1:1 to about 5:1.
Representative examples are shown in U.S. Pat. Nos. 3,087,936;
3,172,892; 3,219,666; 3,272,746; 3,322,670; 3,652,616; 3,948,800;
and Canada Pat. No. 1,094,044, each of which is incorporated by
reference herein in its entirety.
[0080] Succinate esters are formed by the condensation reaction
between alkenyl succinic anhydrides and alcohols or polyols. Molar
ratios can vary depending on the alcohol or polyol used. For
example, the condensation product of an alkenyl succinic anhydride
and pentaerythritol is a useful dispersant.
[0081] Succinate ester amides are formed by condensation reaction
between alkenyl succinic anhydrides and alkanol amines. For
example, suitable alkanol amines include ethoxylated
polyalkylpolyamines, propoxylated polyalkylpoly-amines and
polyalkylpolyamines such as polyethylene polyamines. One example is
propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305, incorporated by reference herein
in its entirety.
[0082] The molecular weight of the alkenyl succinic anhydrides used
in the preceding paragraphs will range between about 800 and 2,500.
The above products can be post-reacted with various reagents such
as sulfur, oxygen, formaldehyde, carboxylic acids such as oleic
acid, 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,
including those derived from mono-succinimides, bis-succinimides
(also known as disuccinimides), and mixtures thereof.
[0083] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No. 4,767,55
1, incorporated by reference herein in its entirety. Process aids
and catalysts, such as oleic acid aid sulfonic acids, can also be
part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S.
Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953;
3,798,165; and 3,803,039, which are incorporated herein by
reference in its entirety.
[0084] Typical high molecular weight aliphatic acid modified
Mannich condensation products useful in this invention can be
prepared from high molecular weight alkyl-substituted
hydroxyaromatics or HN(R).sub.2 group-containing reactants.
[0085] Examples of high molecular weight alkyl-substituted
hydroxyaromatic compounds are polypropylphenol, polybutylphenol,
and other polyalkylphenols. These polyalkylphenols can be obtained
by the alkylation, in the presence of an alkylating catalyst, such
as BF.sub.3, of phenol with high molecular weight polypropylene,
polybutylene, and other polyalkylene compounds to give alkyl
substituents on the benzene ring of phenol having an average
600-100,000 molecular weight.
[0086] Examples of HN(R).sub.2 group-containing reactants are
alkylene polyamines, principally polyethylene polyamines. Other
representative organic compounds containing at least one
HN(R).sub.2 group suitable for use in the preparation of Mannich
condensation products are well known and include mono- and di-amino
alkanes and their substituted analogs, e.g., ethylamine and
diethanol amine; aromatic diamines, e.g., phenylene diamine,
diamino naphthalenes; heterocyclic amines, e.g., morpholine,
pyrrole, pyrrolidine, imidazole, imidazolidine, and piperidine;
melamine and their substituted analogs.
[0087] Examples of alkylene polyamide reactants include
ethylenediamine, diethylene triamine, triethylene tetraamine,
tetraethylene pentaamine, pentaethylene hexamine, hexaethlylene
heptaamine, heptaethylene octaamine, octaethylene nonaamine,
nonaethylene decamine, decaethylene undecamine, and mixtures of
such amines. Some preferred compositions correspond to formula
H.sub.2N--(Z--NH--).sub.nH, where Z is a divalent ethylene and n is
1 to 10 of the foregoing formula. Corresponding propylene
polyamines such as propylene diamine and di-, tri-, tetra-,
pentapropylene tri-, tetra-, penta- and hexaamines are also
suitable reactants. Alkylene polyamines usually are obtained by the
reaction of ammonia and dihalo alkanes, such as dichloro alkanes.
Thus, the alkylene polyamines obtained from the reaction of 2 to 11
moles of ammonia with 1 to 10 moles of dichloro alkanes having 2 to
6 carbon atoms and the chlorines on different carbons are suitable
alkylene polyamine reactants.
[0088] Aldehyde reactants useful in the preparation of the high
molecular products useful in this invention include aliphatic
aldehydes such as formaldehyde (such as paraformaldehyde and
formalin), acetaldehyde and aldol (b-hydroxybutyraldehyde, for
example). Formaldehyde or a formaldehyde-yielding reactant is
preferred.
[0089] Hydrocarbyl substituted amine ashless dispersant additives
are well known to those skilled in the art. See, for example, U.S.
Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209,
and 5,084,197, each of which is incorporated by reference in its
entirety.
[0090] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
about 500 to about 5000 or a mixture of such hydrocarbylene groups.
Other preferred dispersants include succinic acid-esters and
amides, alkylphenol-polyamine coupled Mannich adducts, their capped
derivatives, and other related components. Such additives may be
used in an amount of about 0.1 to 20 weight percent, preferably
about 0.1 to 8 weight percent.
[0091] Pour Point Depressants
[0092] Conventional pour point depressants (also known as lube oil
flow to improvers) may be added to the compositions of the present
invention if desired. These pour point depressants 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 pout 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, and are incorporated
herein by reference. 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.
[0093] Corrosion Inhibitors
[0094] 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 and
tiiazoles. See, for example, U.S. Pat. Nos. 2,719,125; 2,719,126;
and 3,087,932, incorporated herein by reference in their entirety.
Such additives may be used in an amount of about 0.0 1 to 5 weight
percent, preferably about 0.0 1 to 1.5 weight percent.
[0095] Seal Compatibility Additives
[0096] Seal compatibility agents help to swell elastomeric seals.
Suitable seal compatibility agents for lubricating oils include
organic phosphates, aromatic esters, aromatic hydrocarbons, esters
(butylbenzyl phthalate, for example), and polybutenyl succinic
anhydride. Such additives may be used in an amount of about 0.01 to
3 weight percent, preferably about 0.01 to 2 weight percent.
[0097] Anti-Foam Agents
[0098] 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.
[0099] Inhibitors and Antirust Additives
[0100] 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 in
"Lubricants and Related Products ", op. cit.
[0101] 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.
[0102] Typical Additive Amounts
[0103] 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 table below. However, 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.
[0104] Note that many of the additives are shipped from the
manufacturer and used with a certain amount of processing oil
solvent in the formulation. Accordingly, these weight amounts, as
well as other amounts mentioned in this patent, are directed to the
amount of active ingredient (that is the non-solvent 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 0.01-40 0.01-30,
preferably 0.01-15 Improver Antioxidant 0.01-5 0.01-1.5 Corrosion
0.01-5 0.01-1.5 Inhibitor Anti-wear 0.01-6 0.01-4 Additive Pour
Point 0.01-5 0.01-1.5 Depressant Anti-foam Agent 0.001-3 0.001-0.15
Base Oil Balance Balance
EXAMPLES
[0105] The viscosity index enhancement for the following pairs of
components is measured over a varied range of relative
concentrations of base oils (a) Hydrocarbyl Aromatic, (b) PAO 4,
and (c) HDT 4 to Olefin Oligomer as shown as FIG. 1 and Table
2.
[0106] A series of blends of differing ratios of olefin oligomer
and base stock are made, and the viscosity index enhancement from
linearity is measured as shown in FIG. 1 and Table 2.
[0107] The olefin oligomer used is a polymer composition comprising
a is polymer of decene-1 possessing a viscosity at 100.degree. C.
of approximately 150 cSt, and a Mn=3,900, Mw=8,300 with a
Mw/Mn=2.09. The hydrocarbyl aromatic used is alkylated naphthalene
(primarily mono-alkylated) having a viscosity of approximately 4.7
cSt at 100.degree. C., where the hydrocarbyl group is primarily
C.sub.16. The polyalphaolefin oil used is primarily timers and
tetramers of decene-1 having a viscosity of approximately 4 cSt at
100.degree. C. The paraffinic oil used is a hydrotreated oil (Group
II) having a viscosity of approximately 4.5 cSt at 100.degree. C.,
and approximately 22.7 cSt at 40.degree. C. Kinematic viscosities
are measured by ASTM D 445.
[0108] The effect on viscosity index of differing ratios of
different base oils to olefin oligomer is shown in Table 2 and FIG.
1.
[0109] At a 9:1 ratio of paraffinic base oils (Hydrotreated 4) to
olefin oligomer, a 21-viscosity index number enhancement is noted.
This enhancement peaks at a ratio of about 4:1 paraffinic base oils
to olefin oligomer with a value of approximately 28. The degree of
enhancement decreases at lower ratios.
[0110] At a 9:1 ratio of polyalphaolefin oil (PAO 4 sample) to
olefin oligomer, a 27-viscosity index number enhancement is noted.
This enhancement peaks at a ratio of about 4:1 polyalphaolefin base
oil to olefin oligomer, with a value of approximately 35. The
degree of enhancement then decreases at lower ratios.
[0111] At a 9:1 ratio of hydrocarbyl aromatic (hydrocarbyl aromatic
sample) to olefin oligomer, a 34-viscosity index number enhancement
is noted. This enhancement peaks at a ratio of about 4:1
hydrocarbyl aromatic to olefin oligomer with a value of about 38.
These results for the hydrocarbyl aromatic are unexpected and
significantly higher than those viscosity index number enhancements
found for the above paraffinic oil and polyalphaolefin fluid cited
above. In all examples, the degree of enhancement decreases at
lower ratios, but remarkably the rate of decrease for the olefin
oligomer and hydrocarbyl aromatic combination is much less than for
the other mixtures.
3TABLE 2 Viscosity Index Enhancement At Differing Ratios Of Base
Stock To Olefin Oligomer Ratio of Base infinity 9.0 5.7 4.0 2.3 1.5
1.0 0.7 0.0 Stock/Olefin Oligomer Base Stock: Viscosity Index
Enhancement Hydrocarbyl 0.0 34.4 38.4 37.6 35.4 31.5 25.9 0.0
Aromatic (Comprising C16 alkylated naphthalene PAO 4 0.0 27.0 34.8
31.7 25.3 21.1 0.0 HDT 4 0.0 21.0 25.5 28.4 26.6 21.4 16.9 0.0
(Hydrotreated Base Oil)
[0112] These data clearly show the superiority of the olefin
oligomer and hydrocarbyl aromatic mixture over the entire range of
base stock to olefin oligomer ratios. For example, benefit is
clearly derived from a ratio of about 1:2 to 50:1. The greatest
benefit appearing at a ratio of approximately :1 to about 20:1,
more so at about 1:1 to about 10:1 considering the hydrocarbyl
aromatic: olefin oligomer combination.
4TABLE 3 Typical Base Stock Properties Hydrocarbyl HDT 4 Aromatic
PAO 4 GTL 4 D 445 Kinematic Viscosity 22.65 29.3 18 15.6 at
40.degree. C., cSt D 445 Kinematic Viscosity 4.55 4.7 4 3.8 at
100.degree. C., cSt D2272 Viscosity Index 116 75 120 138 D1500 ASTM
Color L0.5 1.0 0 0 D2007 Saturates, wt % 97 na 100 na D2622 Sulfur,
ppm 60 150 0 0 API Group/Base Oil II V IV Classification
[0113] Lubricant compositions in Table 4 are examples of the
instant invention, with such compositions not limiting the
invention.
5TABLE 4 Lubricant Compositions Examples: 4.1 4.2 4.3 4.4 4.5 4.6
4.7 4.8 Ratio of 40:1 4:1 1:1 40:1 4:1 1:1 20:1 10:1 Hydrocarbyl
Aromatic/Olefin Oligomer Compositions Olefin Oligomer 0.3 5 10 0.5
2 4.5 1 3 Hydrocarbyl 12 20 10 20 8 4.5 20 30 Aromatic
Dispersant/Deterent/ 6 12 14 7 10 15 9 8 Inhibitor Performance
Additive Package PAO 10 Bal 40 Bal 30 HDT 4 Bal 20 Bal Bal 20 GTL 4
Balance Bal 40 Bal Ester (KV100 5.5 6 10 2 2 cSt; VI = 131 150 SUS
SPN 10 5 20 2
[0114] All U.S. patents, non-U.S. patents and applications, and
non-patent references cited in this application are hereby
incorporated in their entirety by reference.
* * * * *
References