Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICATING OIL COMPOSITIONS
WITH IMPROVED FRICTION PROPERTIES
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to lubricating oil compositions suitable for use
in internal combustion engines.
Background
[0002] 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.
[0003] 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,
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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 l or
organic molybdenum compounds including molybdenum dithiocarbamates,
molybdenum phosphorodithioates, molybdenum complexes of amines andl 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.
SITMMARY OF THE INVENTION
[0004] 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.
[0005] 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
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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
succirumide ashless dispersant.
BRIEF DESCRIPTION OF THE DRAWING
[0006] Figure 1 is a plot of coefficient of friction as a function of
temperature
for various compositions.
DETAILED DISCRIPTION OF THE INVENTION
[0007] 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.
[0008] 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.
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[0009] 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%.
[0010] 1?esirable esters include pentaerythritol esters, derived from mono-,
di-, and poly pentaerythritol polyols reacted with mixed hydrocarbyl acids
(RCOaH), 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 C6 to about C16 or more, with preferable ranges
being about C6 to about C14, 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 C8 and Clo
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% Cg, about 40% Clo, and the remainder approximately 5% C6 and Cia+
moieties. For example, one useful pentaerythritol ester has a viscosity index
of
about 148, a pour point of about 3°C and a kinematic viscosity of about
5.9 cSt
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at 100°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%.
[0011] Esters may also include esters of trimethylolpropane and
trimethylolethane and the like.
[0012] 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 lilee. 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 C6 up to about C6o with a range of about C8 to about C4o 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 °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 olefins, and the
like.
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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.
[0013] 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 AlCl3, BF3, or HF may be used.
In some cases, milder catalysts such as FeCl3 or SnCl4 are preferred. Other
alkylation technology uses zeolites or solid super acids.
[0014] Fuel economy enhancements are seen with synergistic miaetures 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 concentra-
tions 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
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cSt at 100 °C and similar viscosity indices of approximately 110 to
approximately 150 or greater.
[0015] 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 foi~nulated lubricant.
[0016] In the instant invention, use of these amorphous olefin copolymers
gives surprising low-temperature pumpability performance in lubricant
compositions.
[0017] 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
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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.
[0018] For example, one preferred composition comprising about 20%
hydrocarbyl aromatic, about 40% Group II paraffmic base stock, about 3 weight
percent borated polyisobutyl succinimide ashless dispersant is found to be
particularly useful. Useful ashless dispersants are described below.
[0019] Group II andlor Group III hydroprocessed or hydrocracked base
stocks, including wax isomerates, or their synthetic counterparts such as
polyalphaolefm 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
Clz,
C14, C16, and/or C1g alkylated naphthalenes. In some instances, hydrocarbyl
aromatics products comprising substantially mono-alkylated naphthalene can be
preferred.
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[0020] 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.
[0021] 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, FL; ISBN 0-89573-177-0, which
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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).
Base Oil
[0022] 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.
[0023] 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.APLor~) 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
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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.
Base Oil Properties
Saturates Sulfur Viscosity Index
Group <90 &/or >0.03% & >_80 & <120
I
Group >_90 & <_0.03% & >_80 & <120
II
Group >_90 & <_0.03 % >_ 120
III &
Grroup Defined as
IV polyalphaolefins
(PAO)
Group All other
V base oil
stocks not
included
in Groups
I, II, III,
or IV
[0024] 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 paraffmic, 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,
hydrorefmed, or solvent extracted.
[0025] Synthetic oils include hydrocarbon oil. Hydrocarbon oils include oils
such as polymerized and interpolymerized olefins (polybutylenes,
polypropylenes, propylene isobutylene copolymers, ethylene-olefin copolymers,
and ethylene-alphaolefin copolymers, for example). Polyalphaolefm (PAO) oil
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base stocks are a commonly used synthetic hydrocarbon oil. By way of
example, PAOs derived from Cg, Clo, C12, C14 olefins or mixtures thereof may
be
utilized. See U.S. Patents 4,956,122; 4,827,064; and 4,827,073, which are
incorporated herein by reference in their entirety.
[0026] 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°C). The
PAOs are
typically comprised of relatively low molecular weight hydrogenated polymers
or oligomers of alphaolefms which include, but are not limited to, C2 to about
C32 alphaolefms with the C8 to about C16 alphaolefins, such as 1-octene,
1-decene, 1-dodecene and the like, being preferred. The preferred
polyalphaolefms 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 C14 to C1g 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.
[0027] 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. Patent No. 4,149,178 or U.S. Patent
No. 3,382,291 may be conveniently used herein. Other descriptions of PAO
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synthesis are found in the following U.S. Patent 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 C14 to CI8 olefins are described in U.S.
4,218,330. All of the aforementioned patents are incorporated by reference
herein in their entirety.
[0028] 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.
[0029] 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.
Patent No. 5,055,626. Other alkylbenzenes are described in European Patent
Application No. 168534 and U.S. Patent 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 allcylbenzenes (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 allcylated aromatics which may be used when
desirable are described, for example, in "Synthetic Lubricants and High
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Performance Functional Fluids", Dressler, H., chap 5, (R. L. Shubkin (Ed.)),
Marcel Dekker, N.Y. 1993.
[0030] 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. Patent 5,075,269,
the disclosure of which is incorporated herein by reference in its entirety.
Processes for making hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in U.S. Patents
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 US 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°C of about
3 cSt to
about 50 cSt, preferably about 3 cSt to about 30 cSt, more preferably about
3.5
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cSt to about 25 cSt, as exemplified by GTL 4 with kinematic viscosity of about
4.0 cSt at 100°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°C or
lower,
and under some conditions may have advantageous pour points of about -
25°C
or lower, with useful pour points of about -30°C to about -40°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.
Patent Nos. 6,080,301; 6,090,989, and 6,165,949 for example, and are
incorporated herein in their entirety by reference.
[0031] 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°C, whereas by
comparison
commercial Group II base oils can have kinematic viscosities, up to about 15
cSt
at 100°C, and commercial Group III base oils can have kinematic
viscosities, up
to about 10 cSt at 100°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.
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[0032] 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 C3_8 fatty acid
esters,
or the C130xo acid diester of tetraethylene glycol, for example).
[0033] 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, malefic acid, azelaic acid, suberic acid, sebacic acid,
fiunaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic
acid,
allcenyl 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.
[0034] 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-
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erythritol) with alkanoic acids containing at least about 4 carbon atoms
(prefer-
ably C~ to C3o acids such as saturated straight chain fatty acids including
caprylic
acid, capric acid, lauric acid, myristic acid, palinitic 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).
[0035] 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
to about 10 carbon atoms. These esters are widely available commercially, for
example, the Mobil P-41 and P-51 esters ExxonMobil Chemical Company).
[0036] 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.
[0037] 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.
[0038] 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
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base oils as the base stocks used in combination with the components of this
invention to provide the above-documented superior performance
characteristics.
[0039] 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.
Anitwear and EP Additives
[0040] Internal combustion engine lubricating oils require the presence of
antiwear andlor 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.
[0041] 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)(ORl)(OR~)]2 where Rl and R~ are C1-C1g alleyl groups, preferably
C2-C12 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.
[0042] However, it is found that the phosphorus from these additives has a
deleterious effect on the catalyst in catalytic converters and also on oxygen
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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 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
R3R4C=CRSR6
where each of R3-R6 are independently hydrogen or a hydrocarbon radical.
Preferred hydrocarbon radicals are alkyl or alkenyl radicals. Any two of R3-R6
may be connected so as to form a cyclic ring. Additional information
concerning sulfurized olefins and their preparation can be found in U.S.
Patent
No. 4,941,984, incorporated by reference herein in its entirety.
[0044] The use of polysulfides of thiophosphorous acids and thiophosphorous
acid esters as lubricant additives is disclosed in U.S. Patent 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. Patent 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 phosphate, for example) as antiwear additives in lubricants
is
disclosed in U.S. Patent No. 4,501,678. U.S. Patent 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.
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Patent No. 5,693,598. Thiocarbamate/molybdenum complexes such as moly-
sulfur alkyl dithiocarbamate trimer complex (R=C8-C1g allcyl) are also useful
antiwear agents. Each of the aforementioned patents is incorporated by
reference herein in its entirety.
[0045] Esters of glycerol may be used as antiwear agents. For example,
mono-, di, and tri-oleates, mono-palmitates and mono-myristates may be used.
[0046] ZDDP is combined with other compositions that provide antiwear
properties. U.S. Patent 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.
Patent 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.
[0047] 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.
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Viscosit5r Index Improvers
[0048] 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.
[0049] 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.
[0050] Examples of suitable viscosity index improvers are polymers and
copolymers of methacrylate, butadiene, olefins, or alkylated styrenes.
Polyisobutylene is a commonly used viscosity index improver. Another suitable
viscosity index improver is polymethacrylate (copolymers of various chain
length alkyl methacrylates, for example), some formulations of which also
serve
as pour point depressants. Other suitable viscosity index improvers include
copolymers of ethylene and propylene, hydrogenated block copolymers of
styrene and isoprene, and polyacrylates (copolymers of various chain length
acrylates, for example). Specific examples include styrene-isoprene or styrene-
butadiene based polymers of 50,000 to 200,000 molecular weight.
[0051] 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.
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Antioxidants
[0052] 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
composi-
tions. See, Klamann in Lubricants and Related Products, op cite, and U.S.
Patent Nos. 4,798,684 and 5,084,197, for example, each of which is
incorporated
by reference herein in its entirety.
[0053] 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 C6+ 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).
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[0054] 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 RgR9R1°N where R8 is an aliphatic, aromatic
or
substituted aromatic group, R9 is an aromatic or a substituted aromatic group,
and Rl° is H, alkyl, aryl or R11S(O)xRla where Rll is an alkylene,
alkenylene, or
arallcylene group, R12 is a higher alkyl group, or an alkenyl, aryl, or
alkaryl
group , and x is 0, 1 or 2. The aliphatic group Rg 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 R8 and R9 are
aromatic or substituted aromatic groups, and the aromatic group may be a fused
ring aromatic group such as naphthyl. Aromatic groups R8 and R9 may be joined
together with other groups such as S.
[0055] 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-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
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[0056] Sulfurized alkyl phenols and alkali or alkaline earth metal salts
thereof
also are useful antioxidants. Low sulfur peroxide decomposers are useful as
antioxidants.
[0057] 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.
[0058] 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.
Detergents
[0059] 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.
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[0060] 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.
[0061] 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.
[0062] Preferred detergents include the alkali or alkaline earth metal salts
of
sulfates, phenates, carboxylates, phosphates, and salicylates.
[0063] 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.
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[0064] 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.
[0065] 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)2, BaO, Ba(OH)2, MgO, Mg(OH)a, for example) with an alkyl
phenol or sulfurized alkylphenol. Useful alkyl groups include straight chain
or
branched C1-C3o alkyl groups, preferably, C4-C2o . 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.
[0066] 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
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ii
.~, ~j ~~_
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 Ci i, preferably C13 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.
[0067] Hydrocarbyl-substituted salicylic acids may be prepared from phenols
by the Kolbe reaction. See U.S. Patent 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.
[0068] Alkaline earth metal phosphates are also used as detergents.
[0069] 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. Patent 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
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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.
Di~ersant
[0070] 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.
[0071] 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.
[0072] 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 allcenyl 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 3,172,892;
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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. Patents 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.
[0073] 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.
[0074] 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.
[0075] 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.
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[0076] Succinate ester amides are formed by condensation reaction between
alkenyl succinic anhydrides and allcanol 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.
[0077] 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.
[0078] Manruch base dispersants are made from the reaction of allcylphenols,
formaldehyde, and amines. See U.S. Patent 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.
[0079] 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)2 group-
containing reactants.
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[0080] Examples of high molecular weight alkyl-substituted hydroxyaromatic
compounds are polypropylphenol, polybutylphenol, and other polyallcylphenols.
These polyalkylphenols can be obtained by the alkylation, in the presence of
an
alkylating catalyst, such as BF3, 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.
[0081] Examples of HN(R)2 group-containing reactants are alkylene
polyamines, principally polyethylene polyamines. Other representative organic
compounds containing at least one HN(R)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,
im_idazole, imidazolidine, and piperidine; melamine and their substituted
analogs.
[0082] 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
allcylene polyamines, in the formula HaN-(Z-NH-)"H, 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
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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.
[0083] 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:
[0084] Hydrocarbyl substituted amine ashless dispersant additives are well
known to one skilled in the art; see, for example, U.S. Patent Nos. 3,275,554;
3,438,757; 3',565,804; 3,755,433, 3,822,209, and 5,084,197, which are
incorporated her ein in their entirety by reference.
[0085] 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. ~ther 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.
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Pour Point Depressants
[0086] 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
haloparaffm waxes and aromatic compounds, vinyl carboxylate polymers, and
terpolymers of dialkylfumarates, vinyl esters of fatty acids and allyl vinyl
ethers.
U.S. Patent 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 andlor 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.
Corrosion Inhibitors
[0087] 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. Patent 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.
Seal Comnatibility Additives
[0088] Seal compatibility agents help to swell elastomeric seals by causing a
chemical reaction in the fluid or physical change in the elastomer. Suitable
seal
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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.
Anti-Foam Agents
[0089] Anti-foam agents may advantageously be added to lubricant composi-
tions. 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.
Inhibitors and Antirust Additives
[0090] 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 I~lamann in Lubricants and Related Products, op cite.
[0091] 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
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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.
Friction modifiers
[0092] 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.
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[0093] 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.
[0094] 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.
Typical Additive Amounts
[0095] When lubricating oil compositions contain one or more of the
additives discussed above, the additives) 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.
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[0096] 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.
Table 1. Typical Amounts of Various Lubricant Oil Components
Approximate WeightApproximate Weight
Com ound Percent (Useful)Percent (Preferred)
Deter ent 0.01-6 0.01-4
Dis ersant 0.1-20 0.1-8
Friction Reducer 0.01-5 0.01-1.5
Viscosity Index 0.0-40 0.01-30, more preferably
Improver 0.01-15
Antioxidant 0.01-5 0.01-1.5
Corrosion Inhibitor0.01-5 0.01-1.5
Anti-wear Additive0.01-6 0.01-4
Pour Point De ressant0.0-5 0.01-1.5
Anti-foam A ent 0.001-3 0.001-0.15
Base Oil Balance Balance
Experimental
[0097] Unless otherwise specified, kinematic viscosity at 40°C or
100°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.
[0098]~ The hydrocarbyl aromatic in the following examples is alkylated
naphthalene (primarily mono-alkylated) having a kinematic viscosity of
approximately 4.6 cSt at 100 °C. The primarily mono-alkylated
naphthalene is
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prepared by the alkylation of naphthalene with an olefin primarily comprised
of
1-hexadecene.
[0099] In the Examples, the components listed below are used in the lubricant
compositions:
Table 2. Typical Base Stock Properties
GpIIIHydro-Hydro- PA PE TMP
Hydrocarb
PA
4 treatedtreatedyl O O derivedderived
4 6
A B Aromatic ester ester
D 445 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
D 2272Viscosity 138 114 116 75 120138 149 136
Index
D1500 ASTM 0 L5.0 1.0 0 0
Color
ID Saturates,na 96 97 na 100100 0 0
2007
Wt%
D 2662Sulfur, 0 40 60 150 0 0 0 0
ppm
API Group III II II V IV IV V V
[00100] All examples shown herein illustrate the instant invention but do
not limit the composition for this invention.
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[00101) A series of industry-sanctioned Sequence VIB fuel economy
engine tests (ASTM Research Report DOZ-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.
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Table 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 SW-30 lOW-30 lOW-30 lOW-30SW-30 SW-30
Performance Additives 16.1 15.8 15.8 15.7 16.7 16.0
to
deliver approximately
2%
active borated succinimide
type dispersant based
on total
composition
Hydrotreated Base Oil 0 0 0 20.0 0 0
A
Hydrotreated Base Oil 0 0 40.0 20.0 0 0
B
GpIII4 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 derived0 15.0 12.0 9.4 11.0 8.6
ester
Trimethvlolnronane 2.0 0 0 0 2.0 0
derived
ydrocarbyl Aromatic 16.0 4.7 4.9 4.2 7.0 5.6
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 viscosit rade
[00102] 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 lOW-30 automotive engine oil exhibited a surprising
44% fuel economy enhancement. The admixture of 12% of such PE ester to a
SAE lOW-30 automotive engine oil exhibited a surprising 65% fuel economy
enhancement. The admixture of 15% of such PE ester to a SAE lOW-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
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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.
[00103] 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.
[00104] 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% Crroup 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~ 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 paraffmic 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 Figure 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.
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[00105] 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.
[00106] 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.
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Table 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 SW-30 SW-30 SW-30 SW-30
Performance Additives to deliver15.9 16.1 15.7 15.7
approximately 2% active borated
succinimide type dispersant
based on total
com osition
Hydrotreated Base Oil B 37.5 0 44.0 44.0
GpIII4 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 2.0 2.0 2.0 2.0
ester
Hydrocarbyl Aromatic 7.0 16.0 5.5 5.1
Performance
Phase I FEI % 1.1 1. l 1.5 1.6
Overall Enhancement relative Base Base 26 30
to SAE
viscosi ade
[00107] It is surprisingly found that when relatively high concentrations of
Group II/Group III type paraffmic 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% allcylated naphthalene as the hydrocarbyl
aromatic, a fuel economy enhancement of 30% is observed. With the use of
approximately 44% such paraffmic 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.
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The benefit may reach a maximum with the use of about 3% to 30% hydrocarbyl
aromatic, about 40% to about 90% paraffmic 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.
[00108] 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 andlor
hydrocarbyl aromatic such as alkyl naphthalene and / or other co-base oils in
the
finished formulated lubricant.
[00109] 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.
[00110] 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
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reference engine test formulation to establish the base-line FEI value used in
subsequent calculations as described above.
[00111] 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.
Table 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 SW-30 SW-30 SW-30
Performance Additives to deliver approximately16.1 15.4 15.3
2%
active borated succinimide type dispersant
based on
total coin osition
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 ~ ~
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[00112] The inventors have found that the fuel economy benefit can be
fw-ther 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.
[00113] 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.
[00114] 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.
[00115] It is surprisingly found that fuel economy enhancements can be
attained with the use of certain paraffinic base stocks in the presence of
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Examples 6.1 6.2 6.3 6.4
SAE Oil Viscosity SW-30 lOW-30 lOW-30 10W-30
Performance Additive Package 15.9 15.5 15.6 15.5
containing
3% borated succinimide a dis
ersant
Hydrotreated Base Oil A 0 0 35.0 35.0
Hydrotreated Base Oil B 37.5 0 5.0 0
GpIII4 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 ester2.0 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 Base 78 66 44
to SAE
viscosi ade
[0116] 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.
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.
