U.S. patent application number 10/354594 was filed with the patent office on 2003-09-11 for lubricating oil compositions with improved friction properties.
Invention is credited to Baillargeon, David J., Buck, William H., Deckman, Douglas E., Maxwell, William L., Winemiller, Mark D..
Application Number | 20030171223 10/354594 |
Document ID | / |
Family ID | 56290376 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030171223 |
Kind Code |
A1 |
Winemiller, Mark D. ; et
al. |
September 11, 2003 |
Lubricating oil compositions with improved friction properties
Abstract
The present invention concerns friction reducers for use in
lubricating oil compositions which comprise certain groups of
aromatic compounds, esters, narrow mixtures of base stocks, and/or
amorphous polymers such as amorphous olefin copolymers. These
compositions can provide substantial reductions in the coefficient
of friction and fuel economy improving benefits when admixed to
lubricating oils without deleterious effects such as instability,
undesirable high viscosities and deposits. In one aspect of the
invention, pentaerythritol esters and optionally triol esters are
added to lubricating oil compositions to provide reduced friction
and improved fuel economy. In a second aspect of the invention,
similar results are obtained by adding hydrocarbyl aromatics to a
lubricating oil composition containing one or more of Groups II and
III base stock. In a third aspect, the invention concerns a
lubricating oil composition comprising an amorphous olefin
copolymer and one or more of Groups II and III base stocks. In one
embodiment, the third aspect also includes one or more of
hydrocarbyl aromatics and polyol esters as part of the composition.
In a forth aspect, moderate concentrations of hydrocarbyl aromatics
are used in a lubricating oil composition comprising paraffinic
base oil stocks and preferably a borated polyisobutenyl succinimide
ashless dispersant.
Inventors: |
Winemiller, Mark D.;
(Clarksboro, NJ) ; Deckman, Douglas E.; (Mullica
Hill, NJ) ; Maxwell, William L.; (Pilesgrove, NJ)
; Buck, William H.; (West Chester, PA) ;
Baillargeon, David J.; (Cherry Hill, NJ) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
56290376 |
Appl. No.: |
10/354594 |
Filed: |
January 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60353738 |
Jan 31, 2002 |
|
|
|
Current U.S.
Class: |
508/192 ;
508/591 |
Current CPC
Class: |
C10M 2205/0206 20130101;
C10N 2020/04 20130101; C10M 141/06 20130101; C10M 169/044 20130101;
C10M 2215/28 20130101; C10N 2040/25 20130101; C10M 2205/02
20130101; C10M 2205/22 20130101; C10N 2060/14 20130101; C10M
2205/223 20130101; C10M 2209/1023 20130101; C10M 2207/2805
20130101; C10M 2207/283 20130101; C10M 127/06 20130101; C10M
2203/1006 20130101; C10M 169/041 20130101; C10M 2207/024 20130101;
C10M 2207/28 20130101; C10M 2205/173 20130101; C10M 2219/081
20130101; C10M 2203/06 20130101; C10N 2030/06 20130101; C10M 107/02
20130101; C10M 2203/065 20130101; C10M 2203/10 20130101; C10N
2030/54 20200501; C10M 105/38 20130101; C10M 2203/1025 20130101;
C10N 2020/02 20130101; C10M 169/04 20130101; C10M 2201/10 20130101;
C10M 111/02 20130101; C10M 2207/2835 20130101; C10M 2219/086
20130101; C10M 2205/0285 20130101; C10M 2205/028 20130101 |
Class at
Publication: |
508/192 ;
508/591 |
International
Class: |
C10M 139/00 |
Claims
What is claimed is:
1. A lubricating composition comprising a mixture of: (a) one or
more base stocks selected from the group consisting of Group II
base stock, Group III base stocks, and wax isomerates, and (b) an
amorphous olefin copolymer.
2. A lubricating composition as in claim 1 wherein said amorphous
olefin copolymer is provided at about 1 wt % to about 20 wt %.
3. A lubricating composition as in claim 2 further comprising a
member selected from the group consisting of esters, hydrocarbyl
aromatics, and mixtures thereof.
4. A lubricating composition as in claim 3 wherein said member
comprises about 1 wt % to about 30 wt % of the lubricating
composition.
5. A lubricating composition as in claim 3 further comprising a
borated hydrocarbyl-substituted succinimide wherein the hydrocarbyl
group has a M.sub.n from about 1000 to about 5000 and is present at
about at least 0.3 wt % active ingredient.
6. A lubricating composition as in claim 5 wherein said borated
hydrocarbyl-substituted succinimide comprises borated
hydrocarbyl-substituted mono- and bis-succinimides.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] Non-Provisional Application based on Provisional Application
No. 60/353,738 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] 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 compatibility
additives, and antifoam agents are used in lubricating oil
compositions.
[0006] It is critical to maintain sufficiently high lubricating
film thickness on metal surfaces in order to maintain low friction
and reduce wear of metal parts at a variety of operating
temperatures. It is also important to maintain cleanliness over the
entire range of operating conditions while reducing wear to a
minimum and to maintain a good overall lubricant performance under
the most severe operating conditions. Conventional lubricant and
engine oil technology relies heavily on traditional friction
reducers which can be chosen from one or more classes of friction
reducing compounds exemplified by alcohols, hydrocarbyl diols,
hydrocarbyl triols, alkane diols or triols, esters, fatty esters,
hydroxy esters, fatty acid amides such as oleamide, hydroxy alkyl
hydrocarbyl amides, bis hydroxyalkyl hydrocarbyl amides such as
bis(2-hydroxyethyl)oleamide, hydroxy alkyl hydrocarbyl amines, bis
hydroxyalkyl hydrocarbyl amines such as
bis(2-hydroxyethyl)oleylamine, borated counterparts of the above,
acylated counterparts of the above, phosphorus based compositions
such as trioleyl phosphites, molybdenum compounds such as inorganic
molybdenum and/or organic molybdenum compounds including molybdenum
dithiocarbamates, molybdenum phosphorodithioates, molybdenum
complexes of amines and/or alcoholic moieties. Friction reducers
often include mixtures of two or more of the above classes of
components. Several of the above prior art friction reducing
compositions are found to have significant and often undesirable
side-effects. It is thus desirable to have several improved fuel
economy components and/or systems to be able to choose from in the
formulation of high quality fuel economy improving lubricants.
SUMMARY OF THE INVENTION
[0007] The present invention concerns friction reducers for use in
lubricating oil compositions which comprise certain groups of
aromatic compounds, esters, narrow mixtures of base stocks, and/or
amorphous polymers such as amorphous olefin copolymers. These
compositions can provide substantial reductions in the coefficient
of friction and fuel economy improving benefits when admixed to
lubricating oils without deleterious effects such as instability,
undesirable high viscosities and deposits.
[0008] In one aspect of the invention, pentaerythritol esters and
optionally triol esters are added to lubricating oil compositions
to provide reduced friction and improved fuel economy. In a second
aspect of the invention, similar results are obtained by adding
hydrocarbyl aromatics to a lubricating oil composition containing
one or more of Group II base stock, Group III base stock, and wax
isomerate base stock. In a third aspect, the invention concerns a
lubricating oil composition comprising an amorphous olefin
copolymer and one or more of Group II base stock, Group III base
stock, and wax isomerate base stock. In one embodiment, the third
aspect also includes one or more of hydrocarbyl aromatics and
polyol esters as part of the composition. In a forth aspect,
moderate concentrations of hydrocarbyl aromatics are used in a
lubricating oil composition comprising paraffinic base oil stocks
and preferably a borated polyisobutenyl succinimide ashless
dispersant.
BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1 is a plot of coefficient of friction as a function of
temperature for various compositions.
DETAILED DISCRIPTION 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, 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.
[0011] The instant invention concerns certain groups of aromatic
compounds, esters, mixtures of base stocks, and/or amorphous
polymers such as amorphous olefin copolymers that can provide
substantial reductions in the coefficient of friction and fuel
economy improving benefits when admixed to lubricating oils without
deleterious effects such as instability, undesirable high
viscosities and deposits.
[0012] In one aspect, the present invention concerns certain
pentaerythritol esters which are found to provide unexpected and
significant fuel economy improving (friction reducing) benefits
when formulated into lubricants containing hydrocarbyl aromatic
compositions. This fuel economy improvement enhancement can be
further improved with the addition of certain esters to the
above-mentioned pentaerythritol esters. In particular, this
additional fuel economy improvement is seen with a mixed triol
ester and pentaerythritol ester system in the presence of a
relatively low concentration of hydrocarbyl aromatics such as
alkylated naphthalene. Useful concentrations of hydrocarbyl
aromatics range from about 1% or more. We believe that about 2% to
about 45% of such hydrocarbyl aromatics is often preferred, more
preferably about 2% to about 30%, even more preferably about 3% to
about 15%.
[0013] Desirable esters include pentaerythritol esters, derived
from mono-, di-, and poly pentaerythritol polyols reacted with
mixed hydrocarbyl acids (RCO.sub.2H), and where a substantial
amount of the available --OH groups are converted to esters. The
substituent hydrocarbyl groups, R, of the acid moiety and ester
comprise from about C.sub.6 to about C.sub.16 or more, with
preferable ranges being about C.sub.6 to about C.sub.14, and may
comprise alkyl, alkenyl, cycloalkyl, cycloalkenyl, linear,
branched, and related hydrocarbyl groups, and can optionally
contain S, N, and/or O groups. Pentaerythritol esters with mixtures
of substituent hydrocarbyl groups, R, are often preferred. For
example, substituent hydrocarbyl groups, R, may comprise a
substantial amount of C.sub.8 and C.sub.10 hydrocarbyl moieties in
the proportions of about 1:4 to 4:1. In a mode, a preferred
pentaerythritol ester has R groups comprising approximately about
55% C.sub.8, about 40% C.sub.10, and the remainder approximately 5%
C.sub.6 and C.sub.12+ moieties. For example, one useful
pentaerythritol ester has a viscosity index of about 148, a pour
point of about 3.degree. C. and a kinematic viscosity of about 5.9
cSt at 100.degree. C. The pentaerythritol esters can be used in
lubricant compositions at concentrations of about 3% to about 30%,
preferably about 4% to about 20%, and more preferably about 5% to
about 15%.
[0014] Esters may also include esters of trimethylolpropane and
trimethylolethane and the like.
[0015] The hydrocarbyl aromatics that can be used can be any
hydrocarbyl molecule that contains at least about 5% of its weight
derived from an aromatic moiety such as a benzenoid moiety or
naphthenoid moiety, or their derivatives. These hydrocarbyl
aromatics include alkyl benzenes, alkyl naphthalenes, alkyl
diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides,
alkylated bis-phenol A, alkylated thiodiphenol, and the like. The
aromatic can be mono-alkylated, dialkylated, polyalkylated, and the
like. The aromatic can be mono- or poly-functionalized. The
hydrocarbyl groups can also be comprised of mixtures of alkyl
groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl
groups and other related hydrocarbyl groups. The hydrocarbyl groups
can range from about C.sub.6 up to about C.sub.60 with a range of
about C.sub.8 to about C.sub.40 often being preferred. A mixture of
hydrocarbyl groups is often preferred. The hydrocarbyl group can
optionally contain sulfur, oxygen, and/or nitrogen containing
substituents. The aromatic group can also be derived from natural
(petroleum) sources, provided at least about 5% of the molecule is
comprised of an above-type aromatic moiety. Viscosities at
100.degree. C. of approximately 3 cSt to about 50 cSt are
preferred, with viscosities of approximately 3.4 cSt to about 20
cSt often being more preferred for the hydrocarbyl aromatic
component. In one embodiment, an alkyl naphthalene where the alkyl
group is primarily comprised of 1-hexadecene is used. Other
alkylates of aromatics can be advantageously used. Naphthalene, for
example, can be alkylated with olefins such as octene, decene,
dodecene, tetradecene or higher, mixtures of similar olefms, and
the like. Useful concentrations of hydrocarbyl aromatic in a
lubricant oil composition can be about 2% to about 25%, preferably
about 4% to about 20%, and more preferably about 4% to about 15%,
depending on the application.
[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), Interscience 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), Interscience 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 SnCl4 are preferred. Other alkylation technology
uses zeolites or solid super acids.
[0017] Fuel economy enhancements are seen with synergistic mixtures
of (a) Group II or Group III paraffinic oil blends, including wax
isomerate base oils, and (b) hydrocarbyl aromatics. In particular,
the above mentioned base stocks comprising certain hydroprocessed
base oils, in the presence of low concentrations of polyol based
esters (such as those derived from trimethylolpropane and mixed
hydrocarbyl acids), and hydrocarbyl aromatics (such as alkylated
naphthalene) are found to provide unexpected and significant fuel
economy improving (friction reducing) benefits when directly
compared to lubricants containing relatively high quantities of
about 40% of high quality synthetic fluids derived from olefin
oligomers such as oligomers of 1-decene. For the comparison, both
groups of base stocks have viscosities of about 4 to about 50 cSt
at 100.degree. C. and similar viscosity indices of approximately
110 to approximately 150 or greater.
[0018] In another aspect of the invention, certain amorphous olefin
copolymers are found to provide unexpected and significant fuel
economy improving (friction reducing) benefits when formulated into
lubricants, especially those containing significant amounts of
Group II or Group III base oils, including wax isomerates, having
viscosity indices of about 110 to about 150 or greater. Such olefin
copolymers are not predominantly crystalline. Copolymers used in
this invention have molecular weights in the range of about 20,000
or higher, preferably 60,000 or higher, more preferably 100,000 or
higher and even more preferably 150,000 or higher. For example, in
one embodiment, amorphous etheylene-propylene copolymers comprising
significant to major amounts of propylene-derived copolymers have
molecular weights in the range of about 20,000 or higher. We
believe that the fuel economy benefit can be further enhanced when
the above amorphous olefin copolymer is used in the presence of a
traditional ester and/or hydrocarbyl aromatic such as alkyl
naphthalene at concentrations of about 1% to about 30% or more,
preferably about 2% to about 25%, or more preferably about 3% to
about 20% in the finished formulated lubricant.
[0019] In the instant invention, use of these amorphous olefin
copolymers gives surprising low-temperature pumpability performance
in lubricant compositions.
[0020] In another aspect of the invention, significant fuel economy
enhancements are attained with the use of moderate concentrations
of hydrocarbyl aromatics, preferably in the presence of at least a
minor concentration of Group II or Group III hydrocracked and/or
hydrotreated base stocks, including wax isomerates. These
hydrocarbyl aromatics are described above. Group II and Group III
base stocks and wax isomerate base stocks are described below. We
also believe that the presence of certain ashless dispersants can
significantly contribute to the fuel economy enhancements
observed.
[0021] For example, one preferred composition comprising about 20%
hydrocarbyl aromatic, about 40% Group II paraffinic base stock,
about 3 weight percent borated polyisobutyl succinimide ashless
dispersant is found to be particularly useful. Useful ashless
dispersants are described below.
[0022] Group II and/or Group III hydroprocessed or hydrocracked
base stocks, including wax isomerates, or their synthetic
counterparts such as polyalphaolefin lubricating oils are preferred
as lubricating base stocks when used in conjunction with the
components of each of the aspects of the present invention. At
least about 20% of the total composition should comprise such Group
II or Group III base stocks, including wax isomerates, with at
least about 30% on occasion being more preferable, with at least
about 50% on occasion being more preferable and more than about 80%
on occasion being even more preferable. Gas-to-Liquids 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
stocks can be used to advantage and can often be preferred. 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,
including wax isomerates, with up to lesser quantities of alternate
fluids such as the above described hydrocarbyl aromatics as
exemplified by C.sub.12, C.sub.14, C.sub.16, and/or C.sub.18
alkylated naphthalenes. In some instances, hydrocarbyl aromatics
products comprising substantially mono-alkylated naphthalene can be
preferred.
[0023] Other components, including effective amounts of co-base
stocks, and various performance additives can be advantageously
used with the components 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 such as those derived from gas to liquids type
technology, 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, including wax isomerates, predominate and make up at least
about 50% of the total base stocks contained in fluids comprised of
the elements of the above invention requiring a substantial portion
of such stocks. The base stocks, co-base stocks and other
performance additives are discussed in more detail below.
[0024] 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).
[0025] Base Oil
[0026] 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.
[0027] 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 polyalphaolefms (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 Oil 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
[0028] 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 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.
[0029] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefm 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.
[0030] 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 the C.sub.8 to about C.sub.16
alphaolefms, 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
1.5 to 12 cSt.
[0031] 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. Nos. 4,149,178 or 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.
[0032] Other useful synthetic lubricating base stocks oils may also
be utilized, for example those described in the seminal work
"Synthetic Lubricants", Gunderson and Hart, Reinhold Publ. Corp.,
New York 1962, which is incorporated in its entirety.
[0033] In alkylated aromatic stocks, the alkyl substituents are
typically alkyl groups of about 8 to 25 carbon atoms, usually from
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.
[0034] 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, the disclosure of which is incorporated
herein by reference in its entirety. Processes for making
hydrocracked/hydroisomeri- zed 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. Each of the aforementioned patents is incorporated
herein in their entirety. Particularly favorable processes are
described in European Patent Application Nos. 464546 and 464547,
also incorporated herein by reference. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat Nos. 4,594,172
and 4,943,672, the disclosure of which is incorporated herein by
reference in their 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
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.
[0035] 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 olefm 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.
[0036] 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).
[0037] 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 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, 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.
[0038] 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 dipenta-erythritol) with
alkanoic acids containing at least about 4 carbon atoms (preferably
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 of any of these
materials).
[0039] Suitable synthetic ester components include the 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. These esters are widely available commercially, for example,
the Mobil P-41 and P-51 esters ExxonMobil Chemical Company).
[0040] 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.
[0041] 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. Another class of oils includes polymeric tetrahydrofurans and
the like.
[0042] Besides unique additive effects of hydrocarbyl aromatics and
high molecular weight olefin oligomers of this invention, we
believe that highly refined, low sulfur Group II/III base oils
(such as hydroprocessed oils, HDP) and wax isomerate base oil may
be used in place or in addition to Group IV and V base oils as the
base stocks used in combination with the components of this
invention to provide the above-documented superior performance
characteristics.
[0043] 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.
[0044] Anitwear and EP Additives
[0045] 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 specifications for engine oil performance have
exhibited a trend for improved antiwear properties of the oil.
Antiwear and extreme EP additives perform this role by reducing
friction and wear of metal parts.
[0046] 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 dialkyldithio-phosphate in which the
primary metal constituent is zinc, or zinc dialkyldithio-phosphate
(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. The
ZDDP is typically used in amounts of from about 0.4 to 1.4 weight
percent of the total lube oil composition, although more or less
can often be used advantageously.
[0047] 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.
[0048] 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
[0049] 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
olefms and their preparation can be found in U.S. Pat. No.
4,941,984, incorporated by reference herein in its entirety.
[0050] 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. 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 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.
[0051] Esters of glycerol may be used as antiwear agents. For
example, mono-, di, and tri-oleates, mono-palmitates and
mono-myristates may be used.
[0052] 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.
Each of the aforementioned patents is incorporated herein by
reference in its entirety.
[0053] 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. Such
additives may be used in an amount of about 0.01 to 6 weight
percent, preferably about 0.01 to 4 weight percent.
[0054] Viscosity Index Improvers
[0055] 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.
[0056] 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.
[0057] 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 formulafions 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
50,000 to 200,000 molecular weight.
[0058] Viscosity index improvers may be used in an amount of about
0.01 to 8 weight percent, preferably about 0.01 to 4 weight
percent.
[0059] Antioxidants
[0060] 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, each of which is
incorporated by reference herein in its entirety.
[0061] 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).
[0062] 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 about 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.
[0063] 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.
[0064] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants. Low sulfur peroxide
decomposers are useful as antioxidants.
[0065] 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.
[0066] 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.
[0067] Detergents
[0068] 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.
[0069] Salts that contain a substantially stoichiometric 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.
[0070] 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.
[0071] Preferred detergents include the alkali or alkaline earth
metal salts of sulfates, phenates, carboxylates, phosphates, and
salicylates.
[0072] 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.
[0073] 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.
[0074] 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
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.
[0075] 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
[0076] 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 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.
[0077] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction. See U.S. Pat. No. 3,595,791, which
is 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.
[0078] Alkaline earth metal phosphates are also used as
detergents.
[0079] 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. 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.
[0080] Dispersant
[0081] 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.
[0082] 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 50 to 400 carbon atoms.
[0083] Chemically, many dispersants may be characterized as
phenates, sulfonates, sulfurized phenates, salicylates,
naphthenates, stearates, carbamates, thiocarbamates, phosphorus
derivatives. A particularly useful 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
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. Other
types of dispersant 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. 471 071, to
which reference is made for this purpose. Each of the
aforementioned patents is incorporated herein in its entirety by
reference.
[0084] Hydrocarbyl-substituted succinic acid compounds are popular
dispersants. In particular, succinimide, succinate esters, or
succinate ester amides prepared by the reaction of a
hydrocarbon-substituted succinic acid compound preferably having at
least 50 carbon atoms in the hydrocarbon substituent, with at least
one equivalent of an alkylene amine are particularly useful.
[0085] 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; and 3,652,616,
3,948,800; and Canada Pat. No. 1,094,044, which are incorporated
herein in their entirety by reference.
[0086] 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.
[0087] 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
polyalkenylpolyamines such as polyethylene polyamines. One example
is propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305, incorporated herein by
reference.
[0088] The molecular weight of the alkenyl succinic anhydrides used
in the preceding paragraphs will typically range between 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.
[0089] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No.
4,767,551, which is incorporated herein by reference. Process aids
and catalysts, such as oleic acid and 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 in their
entirety by reference.
[0090] 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.
[0091] 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.
[0092] 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 the 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.
[0093] Examples of alkylene polyamide reactants include
ethylenediamine, diethylene triamine, triethylene tetraamine,
tetraethylene pentaamine, pentaethylene hexamine, hexaethylene
heptaamine, heptaethylene octaamine, octaethylene nonaamine,
nonaethylene decamine, and decaethylene undecamine and mixture of
such amines having nitrogen contents corresponding to the alkylene
polyamines, in the formula H.sub.2N--(Z--NH--).sub.nH, mentioned
before, 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. The alkylene polyamines
are usually 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.
[0094] Aldehyde reactants useful in the preparation of the high
molecular products useful in this invention include the aliphatic
aldehydes such as formaldehyde (also as paraformaldehyde and
formalin), acetaldehyde and aldol (b-hydroxybutyraldehyde).
Formaldehyde or a formaldehyde-yielding reactant is preferred.
[0095] Hydrocarbyl substituted amine ashless dispersant additives
are well known to one 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, which are incorporated herein in their entirety by
reference.
[0096] 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, preferably from about 1000 to 3000, more
preferably from about 1000 to 2000, and even more preferably from
about 1000 to 1600 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.
[0097] Pour Point Depressants
[0098] 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.
[0099] Corrosion Inhibitors
[0100] 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.
[0101] Seal Compatibility Additives
[0102] 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. Such additives may be used in an amount of
about 0.01 to 3 weight percent, preferably about 0.01 to 2 weight
percent.
[0103] Anti-Foam Agents
[0104] 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.
[0105] Inhibitors and Antirust Additives
[0106] 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 in Klamann in
Lubricants and Related Products, op cite.
[0107] 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.
[0108] Friction Modifiers
[0109] 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 O, 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.
[0110] 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 O, 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.
[0111] 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.
[0112] Typical Additive Amounts
[0113] 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 below.
[0114] 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 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 0.0-40 0.01-30,
Improver more preferably 0.01-15 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
[0115] Experimental
[0116] 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.
[0117] The hydrocarbyl aromatic in the following examples is
alkylated naphthalene (primarily mono-alkylated) having a kinematic
viscosity of approximately 4.6 cSt at 100.degree. C. The primarily
mono-alkylated naphthalene is prepared by the alkylation of
naphthalene with an olefin primarily comprised of 1-hexadecene.
[0118] In the Examples, the components listed below are used in the
lubricant compositions:
3TABLE 2 Typical Base Stock Properties Hydro- Hydro- Hydrocarb PE
TMP GpIII treated treated yl PA PA derived derived 4 A B Aromatic O
4 O 6 ester ester D445 Kinematic 15.6 36.2 22.65 29.3 18 31 29.8
18.4 Viscosity at 40 C., cSt D445 Kinematic 3.8 6 4.55 4.7 4 6 5.94
4.2 Viscosity at 100 C., cSt D2272 Viscosity 138 114 116 75 120 138
149 136 Index D1500 ASTM 0 L5.0 1.0 0 0 Color D2007 Saturates, na
96 97 na 100 100 0 0 wt % D2662 Sulfur, ppm 0 40 60 150 0 0 0 0 API
Group III II II V IV IV V V
[0119] All examples shown herein illustrate the instant invention
but do not limit the composition for this invention.
[0120] A series of industry-sanctioned Sequence VIB fuel economy
engine tests (ASTM Research Report D02-1469) were performed to
determine the effect of compositional changes upon fuel economy of
the test lubricants. The fuel economy improvement (FEI) limits for
the various SAE viscosity grades is given in ASTM D 4485. Referring
to Table 3, Comparative Example 3.1 serves as the reference engine
test formulation and establishes the base-line FEI value used in
comparison to that of the inventive Examples. The percent
difference (positive or negative) for FEI between Comparative
Example 3.1 and the standard D 4485 limit is first calculated.
Similarly, the percent differences (positive or negative) for FEI
between the various candidate oils and the standard D4485 limit is
then calculated. The percent advantage of the candidate FEI value
over the Comparative Example 3.1 FEI value is then calculated. The
percent advantage results for each of the candidate oils are
summarized in Table 3 below.
4TABLE 3 Results from fuel economy tests for test oils containing
pentaerythritol esters. Examples 3.1 3.2 3.3 3.4 3.5 3.6 SAE Oil
Viscosity 5W-30 10W-30 10W-30 10W-30 5W-30 5W-30 Performance
Additives to 16.1 15.8 15.8 15.7 16.7 16.0 deliver approximately 2%
active borated succinimide type dispersant based on total
composition Hydrotreated Base Oil A 0 0 0 20.0 0 0 Hydrotreated
Base Oil B 0 0 40.0 20.0 0 0 GpIII 4 0 0 0 0 0 0 4 cS PAO 40.9 45.5
27.3 30.7 63.3 69.8 6 cS PAO 25.0 19.0 0 0 0 0 Pentaerythritol
derived ester 0 15.0 12.0 9.4 11.0 8.6 Trimethylolpropane derived
2.0 0 0 0 2.0 0 ester Hydrocarbyl Aromatic 16.0 4.7 4.9 4.2 7.0 5.6
Performance Phase I FEI % 1.1 1.3 1.2 1.0 1.5 1.6 Overall
Enhancement relative Base 78.0 66.0 44.0 25.0 31.0 to SAE viscosity
grade
[0121] It is unexpectedly found that the addition of from about 8-9
to about 15% of the above-described pentaerythritol ester (PE
ester) provided significant and surprising fuel economy
enhancements. The admixture of 9.4% of such PE ester to a SAE
10W-30 automotive engine oil exhibited a surprising 44%
fuel-economy enhancement. The admixture of 12% of such PE ester to
a SAE 10W-30 automotive engine oil exhibited a surprising 65% fuel
economy enhancement. The admixture of 15% of such PE ester to a SAE
10W-30 automotive engine oil exhibited a surprising 77% fuel
economy enhancement. It is found that increasing concentrations of
such PE ester resulted in greater fuel economy enhancements. Each
of these test oils contained a hydrocarbyl aromatic base oil, and
it is believed that the presence of such hydrocarbyl aromatic may
have contributed to the favorable results obtained.
[0122] It is unexpectedly found that the addition of about 8% or
greater of the above-described pentaerythritol ester (PE ester)
optionally coupled with the addition of 2% trimethylolpropane ester
provided even more significant and more surprising fuel economy
enhancements of at least 25% in Sequence VIB engine testing. These
test oils contain hydrocarbyl aromatics, and it is believed that
the presence of such hydrocarbyl aromatics may have contributed to
the favorable results obtained.
[0123] As shown by Examples 3.2, 3.3, and 3.4 of Table 3, fuel
economy enhancements of up to 78% are found with such combinations.
The benefit may reach a maximum with the use of about 0% to about
20% hydrocarbyl aromatic, about 20% to about 60% Group II type
paraffinic base stock and about 0.5% to about 5% by weight, of the
neat borated polyisobutenyl succinimide ashless dispersant (0.33 wt
% to 3.3 wt % active ingredient) where the polyisobutenyl mono and
bis succinimide is made by the reaction of polyisobutenyl succinic
anhydride with an approximate M.sub.n of 1300 for the PIB group
with amines. Preferred amounts may be from about 4% to about 15%
hydrocarbyl aromatic, about 30% to about 50% Group II type
paraffinic base stocks and about 1% to about 4% borated
polyisobutenyl succinimide ashless dispersant as received by weight
that correspond with HFRR testing of dispersants in FIG. 1. The
neat borated polyisobutenyl succinimide ashless dispersant is
approximately two-thirds active ingredient and provides about 2%
active ingredient when added to the oil blends.
[0124] One of ordinary skill in the art would easily note that
these findings may be extended to any paraffinic base stock. The
inventors note that this discovery may also employ Group III base
stocks, and preferably Gas-to-Liquids or Fischer-Tropsch base
stocks. Thus, as an non-limiting illustrative sample, the inventors
also note that a mixture of about 70 wt % Group III base stock,
about 8 to 9 wt % Pentaerythritol derived ester and about 5 to 6 wt
% Hydrocarbyl Aromatics, with the remainder being a Performance
Additive package will also achieve the same surprising Fuel Economy
increases.
[0125] A series of industry-sanctioned Sequence VIB fuel economy
engine tests is performed to determine the effect of compositional
changes upon fuel economy of the test lubricants. Referring to
Table 4, Comparative Example 4.1 is used as the reference engine
test formulation to establish the base-line FEI value used in
subsequent calculations as described above.
5TABLE 4 Results from fuel economy tests for Group II/Group
III-type paraffinic oil blends and hydrocarbyl aromatics Examples
4.1 4.2 4.3 4.4 SAE Oil Viscosity 5W-30 5W-30 5W-30 5W-30
Performance Additives to deliver 15.9 16.1 15.7 15.7 approximately
2% active borated succinimide type dispersant based on total
composition Hydrotreated Base Oil B 37.5 0 44.0 44.0 GpIII 4 0 0 0
0 4 cS PAO 37.6 40.9 32.8 33.2 6 cS PAO 0 25.0 0 0
Trimethylolpropane derived ester 2.0 2.0 2.0 2.0 Hydrocarbyl
Aromatic 7.0 16.0 5.5 5.1 Performance Phase I FEI % 1.1 1.1 1.5 1.6
Overall Enhancement relative to Base Base 26 30 SAE viscosity
grade
[0126] It is surprisingly found that when relatively high
concentrations of Group II/Group III type paraffinic base stock is
included in lube compositions in the presence of both hydrocarbyl
aromatic and polyol esters, such as those derived from
trimethylolpropane, significant FEI enhancements are unexpectedly
found in Sequence VIB engine testing. With the use of approximately
44% such paraffinic base oil, approximately 2% trimethylol-propane
ester, and approximately 5% alkylated naphthalene as the
hydrocarbyl aromatic, a fuel economy enhancement of 30% is
observed. With the use of approximately 44% such paraffinic base
oils, approximately 2% trimethylol-propane ester, and approximately
5.5% alkylated naphthalene as the hydrocarbyl aromatic, an equally
surprising fuel economy enhancement of 26% is found. The benefit
may reach a maximum with the use of about 3% to 30% hydrocarbyl
aromatic, about 40% to about 90% paraffinic base oil and about 1%
to about 20% trimethylolpropane ester with preferred amounts being
about 4% to about 20% hydrocarbyl aromatic, about 40% or greater of
paraffinic base oils and about 2% to about 10% trimethylolpropane
ester. These engine tests clearly demonstrate the advantages of
such fuel economy improving formulations.
[0127] We believe that the fuel economy benefit can be further
enhanced when the above Group II/III type paraffinic stocks are
used in the presence of about 1% to about 10% or more of any
traditional polyol ester and/or hydrocarbyl aromatic such as alkyl
naphthalene and/or other co-base oils in the finished formulated
lubricant.
[0128] One of ordinary skill in the art would easily note that
these findings may be extended to any paraffinic base stock. The
inventors note that this discovery may also employ Group III base
stocks, and preferably Gas-to-Liquids or Fischer-Tropsch base
stocks. Thus, as an non-limiting illustrative sample, the inventors
also note that a mixture of about 40 wt % Group III base stock,
about 30 to 35% PAO, about 2 wt % Trimethylolpropane and about 4 to
6 wt % Hydrocarbyl Aromatics, with the remainder being a
Performance Additive package will also achieve the same surprising
Fuel Economy increases.
[0129] Certain amorphous olefin copolymers are found to provide
unexpected and significant fuel economy improving (friction
reducing) benefits when formulated into lubricants, especially
those containing significant amounts of Group II or Group III base
oils having viscosity indices of about 110 to about 150 or greater.
A series of industry-sanctioned Sequence VIB fuel economy engine
tests is performed to determine the effect of compositional changes
upon fuel economy of the test lubricants. Comparative Example 5.1
is used as the reference engine test formulation to establish the
base-line FEI value used in subsequent calculations as described
above.
[0130] It is surprisingly found that the addition of 5% of an
amorphous olefin copolymer to a formulated oil blended with mixed
Group II/Group III and polyalpha olefin base stocks derived from
decene-type olefins, that the fuel economy enhancement in Sequence
VIB engine testing is a surprising 26% to 38% enhancement. These
results clearly show the unexpected fuel economy improving benefits
of such formulations comprising amorphous olefin copolymers at
about 1% to about 20% where about 2% to about 15% is preferred and
about 3% to about 10% is most preferred.
6TABLE 5 Results from fuel economy tests for amorphous OCP type oil
blends and hydrocarbyl aromatics Examples 5.1 5.2 5.3 SAE Oil
Viscosity 5W-30 5W-30 5W-30 Performance Additives to deliver 16.1
15.4 15.3 approximately 2% active borated succinimide type
dispersant based on total composition Amorphous OCP 0 5.0 5.0
Hydrotreated Base Oil B 0 31.0 31.0 GpIII 4 0 0 0 4 cS PAO 40.9
39.6 39.7 6 cS PAO 25.0 0 0 Trimethylolpropane derived ester 2.0
2.0 2.0 Hydrocarbyl Aromatic 16.0 7.0 7.0 Performance Phase I FEI %
1.1 1.7 1.5 Overall Enhancement relative to SAE Base 38 26
viscosity grade
[0131] The inventors have found that the fuel economy benefit can
be further enhanced when the above amorphous olefin copolymer is
used in the presence of about 1% to about 10% or more of any
traditional polyol ester and/or hydrocarbyl aromatic such as alkyl
naphthalene and/or other co-base oils in the finished formulated
lubricant.
[0132] One of ordinary skill in the art would easily note that
these findings may be extended to any paraffinic base stock. The
inventors note that this discovery may also employ Group III base
stocks, and preferably Gas-to-Liquids or Fischer-Tropsch base
stocks. Thus, as an non-limiting illustrative sample, the inventors
also note that a mixture of about 30 wt % Group III base stock,
about 40 wt % PAO, about 2 wt % Trimethylolpropane and about 4 to
10 wt % Hydrocarbyl Aromatics, with the remainder being a
Performance Additive package will also achieve the same surprising
Fuel Economy increases.
[0133] Sequence VIB engine testing shows that significant fuel
economy enhancements can be attained with the use of moderate
concentrations of hydrocarbyl aromatics, preferably in the presence
of at least a minor concentration of Group II or Group III, or
hydrocracked and/or hydrotreated base stocks, including wax
isomerate base oils. The presence of certain ashless dispersants
also can significantly contribute to the fuel economy enhancements
observed. A series of industry-sanctioned Sequence VIB fuel economy
engine tests is performed to determine the effect of compositional
changes upon fuel economy of the test lubricants. Comparative
Example 6.1 is used as the reference engine test formulation to
establish the base-line FEI value used in subsequent calculations
as described above.
[0134] It is surprisingly found that fuel economy enhancements can
be attained with the use of certain paraffinic base stocks in the
presence of moderate concentrations of hydrocarbyl aromatics,
preferably in the presence of certain borated polyisobutenyl
succinimide ashless dispersants. As shown by Examples 6.2, 6.3 and
6.4 of Table 6, fuel economy enhancements of up to 77% are found
with such combinations. The benefit may reach a maximum with the
use of about 0% to about 20% hydrocarbyl aromatic, about 20% to
about 60% Group II type paraffinic base stocks and about 0.5% to
about 5% by weight, as received, of a borated polyisobutenyl
succinimide ashless dispersant. Preferred amounts may be from about
4% to about 15% hydrocarbyl aromatic, about 30% to about 50% Group
II type paraffinic base stocks and about 1% to about 4% borated
polyisobutenyl succinimide ashless dispersant as received by weight
that correspond with HFRR testing of dispersants in FIG. 1. The
Sequence VIB fuel economy engine test results clearly show the
unexpected advantages obtainable by using the components of this
invention.
[0135] Table 6. Results from fuel economy tests
hydrocracked/hydrotreated stocks used with synergistic amounts of
hydrocarbyl aromatics as fuel economy improving compositions.
7 Examples 6.1 6.2 6.3 6.4 SAE Oil Viscosity 5W-30 10W-30 10W-30
10W-30 Performance Additive Package 15.9 15.5 15.6 15.5 containing
3% borated succinimide type dispersant Hydrotreated Base Oil A 0 0
35.0 35.0 Hydrotreated Base Oil B 37.5 0 5.0 0 GpIII 4 0 0 0 0 4 cS
PAO 37.6 4.0 22.4 7.5 6 cS PAO 0 23.5 0 25.0 8 cS PAO 0 15.0 0 0
Trimethylolpropane derived ester 2.0 2.0 2.0 2.0 Hydrocarbyl
Aromatic 7.0 40.0 20.0 15.0 Performance Phase I FEI % 1.1 1.0 1.3
0.9 Overall Enhancement relative to Base 78 66 44 SAE viscosity
grade
[0136] One of ordinary skill in the art would easily note that
these findings may be extended to any paraffinic base stock. The
inventors note that this discovery may also employ Group III base
stocks, and preferably Gas-to-Liquids or Fischer-Tropsch base
stocks. Thus, as an non-limiting illustrative sample, the inventors
also note that a mixture of about 30 wt % Group III base stock,
about 30 to 40% PAO, about 2 wt % Trimethylolpropane and about 5 to
40 wt % Hydrocarbyl Aromatics, with the remainder being a
Performance Additive package will also achieve the same surprising
Fuel Economy increases.
[0137] 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