Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
Lubricant Compositions for Direct Injection Engines
BACKGROUND OF THE INVENTION
[0001] The disclosed technology relates to lubricants for internal
combustion
engines, particularly those for spark-ignited direct injection engines.
[0002] Modern engine designs are being developed to improve fuel economy
without sacrificing performance or durability. Historically, gasoline was port-
fuel injected
(PFI), that is, injected through the air intake and entering the combustion
chamber via the
air intake valve. Gasoline direct injection (GDI) involves direct injection of
gasoline into
the combustion chamber.
[0003] In certain situations, the internal combustion engine may exhibit
abnormal
combustion. Abnormal combustion in a spark-initiated internal combustion
engine may be
understood as an uncontrolled explosion occurring in the combustion chamber as
a result
of ignition of combustible elements therein by a source other than the
igniter.
[0004] Pre-ignition may be understood as an abnormal form of combustion
resulting from ignition of the air-fuel mixture prior to ignition by the
igniter. Anytime the
air-fuel mixture in the combustion chamber is ignited prior to ignition by the
igniter, such
may be understood as pre-ignition.
[0005] Without being bound to a particular theory, traditionally, pre-
ignition has
occurred during high speed operation of an engine when a particular point
within the
combustion chamber of a cylinder may become hot enough during high speed
operation
of the engine to effectively function as a glow plug (e.g. overheated spark
plug tip,
overheated burr of metal) to provide a source of ignition which causes the air-
fuel mixture
to ignite before ignition by the igniter. Such pre-ignition may be more
commonly referred
to as hot-spot pre-ignition, and may be inhibited by simply locating the hot
spot and
eliminating it.
[0006] More recently, vehicle manufacturers have observed intermittent
abnormal
combustion in their production of turbocharged gasoline engines, particularly
at low
speeds and medium-to-high loads. More particularly, when operating the engine
at speeds
less than or equal to 3,000 rpm and under a load with a break mean effective
pressure
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(BMEP) of greater than or equal to 10 bars, a condition which may be referred
to as low-
speed pre-ignition (LSPI) may occur in a very random and stochastic fashion.
[0007] The disclosed technology provides a method for reducing,
inhibiting, or
even eliminating LSPI events in direct injection engines by operating the
engines with a
lubricant that contains an ashless dispersant.
SUMMARY OF THE INVENTION
[0008] The disclosed technology provides a method for reducing low speed
pre-
ignition events in a spark-ignited direct injection internal combustion engine
comprising
supplying to the sump a lubricant composition which contains an oil of
lubricating
viscosity and an ashless dispersant. The ashless dispersant may be a
polyisobutylene
succinimide compound.
[0009] The invention provides a method for reducing low speed pre-
ignition events
in a spark-ignited direct injection internal combustion engine comprising
supplying to the
engine a lubricant composition comprising a base oil of lubricating viscosity
and an ashless
dispersant.
[0010] The invention further provides a method as described herein in
which the
engine is operated under a load with a break mean effective pressure (BMEP) of
greater
than or equal to 10 bars.
[0011] The invention further provides a method as described herein in
which
wherein the engine is operated at speeds less than or equal to 3,000 rpm.
[0012] The invention further provides a method as described herein in
which the
engine is fueled with a liquid hydrocarbon fuel, a liquid non-hydrocarbon
fuel, or mixtures
thereof.
[0013] The invention further provides a method as described herein in
which the
engine is fueled by natural gas, liquefied petroleum gas (LPG), compressed
natural gas
(CNG), or mixtures thereof.
[0014] The invention further provides a method as described herein in
which the
ashless dispersant is a polyalkenyl dispersant derived from acylated
polyisobutylene.
[0015] The invention further provides a method as described herein in
which the
ashless dispersant comprises a polyisobutylene succinimide compound.
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[0016] The invention further provides a method as described herein in
which the
polyisobutylene succinimide compound is prepared from an amine comprising one
or
more of aliphatic polyamines, aromatic amines, polyether amines, and mixtures
thereof
[0017] The invention further provides a method as described herein in
which the
acylated polyisobutylene is prepared by a chlorine process, a thermal process,
a free radical
polymerization process, or combinations thereof
[0018] The invention further provides a method as described herein in
which the
lubricant composition further includes at least one other additive selected
from an ashless
antioxidant, a metal containing overbased detergent, a phosphorus-containing
anti-wear
additive, a friction modifier, and a polymeric viscosity modifier.
[0019] The invention further provides a method as described herein in
which the
ashless antioxidant is derived from a 2,6-dialkyl phenol.
[0020] The invention further provides a method as described herein in
which the
ashless antioxidant is a diarylamine compound.
[0021] The invention further provides a method as described herein in
which the
ashless dispersant is present in an amount from 1.0 to 6.5 weight percent of
the lubricant
composition.
[0022] The invention further provides a method as described herein in
which the
lubricating composition includes at least 50 weight % of Group II base oil,
Group III base
oil, or mixtures thereof.
[0023] The invention further provides a method as described herein in
which the
low speed pre-ignition events are reduced to less than 20 LSPI events per
100,000
combustion events.
[0024] The invention further provides a method as described herein in
which there
is a reduction in the number of LSPI events of at least 10 percent.
DETAILED DESCRIPTION
[0025] Various preferred features and embodiments will be described below
by
way of non-limiting illustration.
[0026] As indicated above, when operating the engine at speeds less than
or equal
to 3,000 rpm and under a load with a break mean effective pressure (BMEP) of
greater
than or equal to 10 bars, a low-speed pre-ignition (LSPI) event may occur in
the engine. A
LSPI event may consist of one or more LSPI combustion cycles, and generally
consists of
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multiple LSPI combustion cycles which occur in a consecutive fashion or
alternating
fashion with normal combustion cycles in between. Without being bound to a
particular
theory, LSPI may result from a combustion of oil droplet(s), or a droplet(s)
of oil-fuel
mixture, or combinations thereof, which may accumulate, for example, in the
top land
crevices volume of a piston, or the piston ring-land and ring-groove crevices.
The lubricant
oil may be transferred from below the oil control ring to the piston top land
area due to
unusual piston ring movements. At low speed, high load conditions, in-cylinder
pressures
dynamics (compression and firing pressures) may be considerably different from
in-
cylinder pressures at lower loads, particularly due to strongly retarded
combustion phasing
and high boost and peak compression pressures which can influence ring motion
dynamics.
[0027] At the foregoing loads, LSPI, which may be accompanied by
subsequent
detonation and/or severe engine knock, can cause severe damage to the engine
very
quickly (often within 1 to 5 engine cycles). Engine knock may occur with LSPI
given that,
after the normal spark from the igniter is provided, multiple flames may be
present. The
present invention aims to provide a method for inhibiting or reducing LSPI
events, the
method involving supplying to the engine a lubricant composition comprising an
ashless
dispersant.
[0028] In one embodiment of the invention, the engine is operated at
speeds
between 500 rpm and 3000 rpm, or 800 rpm to 2800 rpm, or even 1000 rpm to 2600
rpm.
Additionally, the engine may be operated with a break mean effective pressure
of 10 bars
to 30 bars, or 12 bars to 24 bars.
[0029] LSPI events, while comparatively uncommon, may be catastrophic in
nature. Hence drastic reduction or even elimination of LSPI events during
normal or
sustained operation of a direct fuel injection engine is desirable. In one
embodiment, the
method of the invention is such that there are less than 20 LSPI events per
100,000
combustion events or less than 10 LSPI events per 100.000 combustion events.
In one
embodiment, there may be less than 5 LSPI events per 100.000 combustion
events, less
than 3 LSPI events per 100.000 combustion events; or there may be 0 LSPI
events per
100.000 combustion events.
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[0030] In one embodiment, the method of the invention provides a
reduction in the
number of LSPI events of at least 10 percent, or at least 20 percent, or at
least 30 percent,
or at least 50 percent.
Fuel
[0031] The method of the present invention involves operating a spark-
ignited
internal combustion engine. In addition to the engine operating conditions and
the
lubricant composition, the composition of the fuel may impact LSPI events. In
one
embodiment, the fuel may comprise a fuel which is liquid at ambient
temperature and is
useful in fueling a spark ignited engine, a fuel which is gaseous at ambient
temperatures,
or combinations thereof
[0032] The liquid fuel is normally a liquid at ambient conditions e.g.,
room
temperature (20 to 30 C). The fuel can be a hydrocarbon fuel, a nonhydrocarbon
fuel, or a
mixture thereof. The hydrocarbon fuel may be a gasoline as defined by ASTM
specification D4814. In an embodiment of the invention the fuel is a gasoline,
and in other
embodiments the fuel is a leaded gasoline, or a nonleaded gasoline.
[0033] The non-hydrocarbon fuel can be an oxygen containing composition,
often
referred to as an oxygenate, to include an alcohol, an ether, a ketone, an
ester of a
carboxylic acid, a nitroalkane, or a mixture thereof. The nonhydrocarbon fuel
can include
for example methanol, ethanol, methyl t-butyl ether, methyl ethyl ketone,
transesterified
oils and/or fats from plants and animals such as rapeseed methyl ester and
soybean methyl
ester, and nitromethane. Mixtures of hydrocarbon and nonhydrocarbon fuels can
include,
for example, gasoline and methanol and/or ethanol. In an embodiment of the
invention,
the liquid fuel is a mixture of gasoline and ethanol, wherein the ethanol
content is at least
volume percent of the fuel composition, or at least 10 volume percent of the
composition,
or at least 15 volume percent, or 15 to 85 volume percent of the composition.
In one
embodiment, the liquid fuel contains less than 15% by volume ethanol content,
less than
10% by volume ethanol content, less than 5% ethanol content by volume, or is
substantially free of (i.e. less than 0.5% by volume) of ethanol.
[0034] In several embodiments of this invention, the fuel can have a
sulfur content
on a weight basis that is 5000 ppm or less, 1000 ppm or less, 300 ppm or less,
200 ppm or
less, 30 ppm or less, or 10 ppm or less. In another embodiment, the fuel can
have a sulfur
content on a weight basis of 1 to 100 ppm. In one embodiment, the fuel
contains about 0
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ppm to about 1000 ppm, about 0 to about 500 ppm, about 0 to about 100 ppm,
about 0 to
about 50 ppm, about 0 to about 25 ppm, about 0 to about 10 ppm, or about 0 to
5 ppm of
alkali metals, alkaline earth metals, transition metals or mixtures thereof.
In another
embodiment the fuel contains 1 to 10 ppm by weight of alkali metals, alkaline
earth metals,
transition metals or mixtures thereof
[0035] The gaseous fuel is normally a gas at ambient conditions e.g.,
room
temperature (20 to 30 C). Suitable gas fuels include natural gas, liquefied
petroleum gas
(LPG), compressed natural gas (CNG), or mixtures thereof In one embodiment,
the engine
is fueled with natural gas.
[0036] The fuel compositions of the present invention can further
comprise one or
more performance additives. Performance additives can be added to a fuel
composition
depending on several factors, including the type of internal combustion engine
and the
type of fuel being used in that engine, the quality of the fuel, and the
service conditions
under which the engine is being operated. In some embodiments, the performance
additives are free of nitrogen. In other embodiments, the additional
performance additives
may contain nitrogen.
[0037] The performance additives can include an antioxidant such as a
hindered
phenol or derivative thereof and/or a diarylamine or derivative thereof; a
corrosion
inhibitor such as an alkenylsuccinic acid; and/or a detergent/dispersant
additive, such as a
polyetheramine or nitrogen containing detergent, including but not limited to
polyisobutylene (PIB) amine dispersants, Mannich detergents, succinimide
dispersants,
and their respective quaternary ammonium salts.
[0038] The performance additives may also include a cold flow improver,
such as
an esterifled copolymer of maleic anhydride and styrene and/or a copolymer of
ethylene
and vinyl acetate; a foam inhibitor, such as a silicone fluid; a demulsifler
such as a
polyoxyalkylene and/or an alkyl polyether alcohol; a lubricity agent such as a
fatty
carboxylic acid, ester and/or amide derivatives of fatty carboxylic acids, or
ester and/or
amide derivatives of hydrocarbyl substituted succinic anhydrides; a metal
deactivator,
such as an aromatic triazole or derivative thereof, including but not limited
to a
benzotriazole such as tolytriazole; and/or a valve seat recession additive,
such as an alkali
metal sulfosuccinate salt. The additives may also include a biocide, an
antistatic agent, a
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deicer, a fluidizer, such as a mineral oil and/or a poly(alpha-olefin) and/or
a polyether, and
a combustion improver, such as an octane or cetane improver.
[0039] The fluidizer may be a polyetheramine or a polyether compound. The
polyetheramine can be represented by the formula R[-OCH2CH(R1)].A, where R is
a
hydrocarbyl group, R1 is selected from the group consisting of hydrogen,
hydrocarbyl
groups of 1 to 16 carbon atoms, and mixtures thereof, n is a number from 2 to
about 50,
and A is selected from the group consisting of --OCH2CH2CH2NR2R2 and --NR3R3,
where
each R2 is independently hydrogen or hydrocarbyl, and each R3 is independently
hydrogen,
hydrocarbyl or -[R4N(R5)]pR6, where R4 is C2-Cio alkylene, R5 and R6 are
independently
hydrogen or hydrocarbyl, and p is a number from 1-7.
[0040] The fluidizer can be a polyether, which can be represented by the
formula
R70[CH2CH(R8)0]qH, where R7 is a hydrocarbyl group, R8 is selected from the
group
consisting of hydrogen, hydrocarbyl groups of 1 to 16 carbon atoms, and
mixtures thereof,
and q is a number from 2 to about 50. The fluidizer can be a hydrocarbyl-
terminated poly-
(oxyalkylene) aminocarbamate as described U.S. Pat. No. 5,503,644. The
fluidizer can be
an alkoxylate, wherein the alkoxylate can comprise: (i) a polyether containing
two or more
ester terminal groups; (ii) a polyether containing one or more ester groups
and one or more
terminal ether groups; or (iii) a polyether containing one or more ester
groups and one or
more terminal amino groups, wherein a terminal group is defined as a group
located within
five connecting carbon or oxygen atoms from the end of the polymer. Connecting
is
defined as the sum of the connecting carbon and oxygen atoms in the polymer or
end
group.
[0041] The performance additives which may be present in the fuel
additive
compositions and fuel compositions of the present invention also include di-
ester, di-
amide, ester-amide, and ester-imide friction modifiers prepared by reacting a
dicarboxylic
acid (such as tartaric acid) and/or a tricarboxylic acid (such as citric
acid), with an amine
and/or alcohol, optionally in the presence of a known esterification catalyst.
These friction
modifiers often derived from tartaric acid, citric acid, or derivatives
thereof may be derived
from amines and/or alcohols that are branched so that the friction modifier
itself has
significant amounts of branched hydrocarbyl groups present within it
structure. Examples
of suitable branched alcohols used to prepare these friction modifiers include
2-
ethylhexanol, isotridecanol, Guerbet alcohols, or mixtures thereof
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[0042] In different embodiments the fuel composition may have a
composition as
described in the following table:
Additive Embodiments (ppm)
A C D
Detergent/dispersant 0 to 2500 25 to 150 500 to 2500
Fluidizer 0 to 5000 1 to 250 3000 to 5000
Demulsifier 0 to 50 0.5 to 5 1 to 25
Corrosion Inhibitor 0 to 200 .5 to 10 20 to 200
Antioxidant 0 to 1000 5 to 125 500 to 1000
Friction Modifier 0 to 600 50 to 175 100 to 750
Fuel Balance to 100% Balance to 100% Balance to 100%
Oil of Lubricating Viscosity
[0043] The lubricating composition comprises an oil of lubricating
viscosity. Such
oils include natural and synthetic oils, oil derived from hydrocracking,
hydrogenation, and
hydrofinishing, unrefined, refined, re-refined oils or mixtures thereof. A
more detailed
description of unrefined, refined and re-refined oils is provided in
International Publication
W02008/147704, paragraphs [0054] to [0056] (a similar disclosure is provided
in US
Patent Publication 2010/0197536, see [0072] to [0073]). A more detailed
description of
natural and synthetic lubricating oils is described in paragraphs [0058] to
[0059]
respectively of W02008/147704 (a similar disclosure is provided in US Patent
Publication
2010/0197536, see [0075] to [0076]). Synthetic oils may also be produced by
Fischer-
Tropsch reactions and typically may be hydroisomerized Fischer-Tropsch
hydrocarbons
or waxes. In one embodiment, oils may be prepared by a Fischer-Tropsch gas-to-
liquid
synthetic procedure as well as other gas-to-liquid oils.
[0044] Oils of lubricating viscosity may also be defined as specified in
the April
2008 version of "Appendix E - API Base Oil Interchangeability Guidelines for
Passenger
Car Motor Oils and Diesel Engine Oils", section 1.3 Sub-heading 1.3. "Base
Stock
Categories". The API Guidelines are also summarized in US Patent US 7,285,516
(see
column 11, line 64 to column 12, line 10). In one embodiment, the oil of
lubricating
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viscosity may be an API Group II, Group III, or Group IV oil, or mixtures
thereof. The
five base oil groups are as follows:
Base Oil Category Sulfur (%) Saturates (%) Viscosity Index
Group I >0.03 and/or <90 80 to 120
Group II <0.03 and >90 80 to 120
Group III <0.03 and >90 >120
Group IV All polyalphaolefins (PAO)
Group V All others not included in Groups I, II, III, or IV
[0045] The amount of the oil of lubricating viscosity present is
typically the
balance remaining after subtracting from 100 weight % (wt %) the sum of the
amount of
the compound of the invention and the other performance additives.
[0046] The lubricating composition may be in the form of a concentrate
and/or a
fully formulated lubricant. If the lubricating composition of the invention
(comprising the
additives disclosed herein) is in the form of a concentrate which may be
combined with
additional oil to form, in whole or in part, a finished lubricant, the ratio
of the of these
additives to the oil of lubricating viscosity and/or to diluent oil include
the ranges of 1:99
to 99:1 by weight, or 80:20 to 10:90 by weight.
[0047] In one embodiment, the base oil has a kinematic viscosity at 100 C
from 2
mm2/s (centiStokes - cSt) to 16 mm2/s, from 3 mm2/s to 10 mm2/s, or even from
4 mm2/s
to 8 mm2/s.
[0048] The ability of a base oil to act as a solvent (i.e. solvency) may
be a
contributing factor in increasing the frequency of LSPI events during
operation of a direct
fuel-injected engine. Base oil solvency may be measured as the ability of un-
additized base
oil to act as a solvent for polar constituents. In general, base oil solvency
decreases as the
base oil group moves from Group Ito Group IV (PAO). That is, solvency of base
oil may
be ranked as follows for oil of a given kinematic viscosity: Group I> Group II
> Group
III > Group IV. Base oil solvency also decreases as the viscosity increases
within a base
oil group; base oil of low viscosity tends to have better solvency than
similar base oil of
higher viscosity. Base oil solvency may be measured by aniline point (ASTM
D611).
[0049] In one embodiment, the base oil comprises at least 30 wt % of
Group II or
Group III base oil. In another embodiment, the base oil comprises at least 60
weight % of
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Group II or Group III base oil, or at least 80 wt % of Group II or Group III
base oil. In one
embodiment, the lubricant composition comprises less than 20 wt % of Group IV
(i.e.
polyalphaolefin) base oil. In another embodiment, the base oil comprises less
than 10 wt
% of Group IV base oil. In one embodiment, the lubricating composition is
substantially
free of (i.e. contains less than 0.5 wt %) of Group IV base oil.
[0050] Ester base fluids, which are characterized as Group V oils, have
high levels
of solvency as a result of their polar nature. Addition of low levels
(typically less than 10
wt %) of ester to a lubricating composition may significantly increase the
resulting
solvency of the base oil mixture. Esters may be broadly grouped into two
categories:
synthetic and natural. An ester base fluid would have a kinematic viscosity at
100 C
suitable for use in an engine oil lubricant, such as between 2 cSt and 30 cSt,
or from 3 cSt
to 20 cSt, or even from 4 cSt to 12 cSt.
[0051] Synthetic esters may comprise esters of dicarboxylic acids (e.g.,
phthalic
acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic
acid, azelaic
acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid
dimer, malonic
acid, alkyl malonic acids, and alkenyl malonic acids) with any of variety of
monohydric
alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl
alcohol,
ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific
examples
of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl
fumarate,
dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate,
didecyl phthalate,
dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the
complex ester
formed by reacting one mole of sebacic acid with two moles of tetraethylene
glycol and
two moles of 2-ethylhexanoic acid. Other synthetic esters include those made
from C5 to
C12 monocarboxylic acids and polyols and polyol ethers such as neopentyl
glycol,
trimethylolpropane, pentaerythritol, dipentaerythritol, and
tripentaerythritol. Esters can
also be monoesters of mono-carboxylic acids and monohydric alcohols.
[0052] Natural (or bio-derived) esters refer to materials derived from a
renewable
biological resource, organism, or entity, distinct from materials derived from
petroleum or
equivalent raw materials. Natural esters include fatty acid triglycerides,
hydrolyzed or
partially hydrolyzed triglycerides, or transesterified triglyceride esters,
such as fatty acid
methyl ester (or FAME). Suitable triglycerides include, but are not limited
to, palm oil,
soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related
materials. Other
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sources of triglycerides include, but are not limited to, algae, animal
tallow, and
zooplankton. Methods for producing bio-lubricants from natural triglycerides
are
described in, e.g., United States Patent Publication 2011/0009300A1.
[0053] In one embodiment, the lubricating composition comprises at least
2 wt %
of an ester base fluid. In one embodiment the lubricating composition of the
invention
comprises at least 4 wt %of an ester base fluid, or at least 7 wt % of an
ester base fluid, or
even at least 10 wt % of an ester base fluid.
Ashless Dispersant
[0054] Dispersants, generally, are well known in the field of lubricants
and
include primarily what is known as ashless dispersants and polymeric
dispersants.
Ashless dispersants are so-called because, as supplied, they do not contain
metal and
thus do not normally contribute to sulfated ash when added to a lubricant.
However,
they may, interact with ambient metals once they are added to a lubricant
which
includes a metal-containing species. Ashless dispersants are characterized by
a polar
group attached to a relatively high molecular weight hydrocarbon chain.
Typical
ashless dispersants include N-substituted long chain alkenyl succinimides,
having a
variety of chemical structures, including those represented by Formula (I):
0 0
R1 1\ JR1
N¨[R2-NFlix-R2-
(I)
where each R1 is independently an alkyl group, frequently a polyisobutylene
group
with a molecular weight (M.) of 500-5000 based on the polyisobutylene
precursor, and
R2 are alkylene groups, commonly ethylene (C2H4) groups.
[0055] Such molecules are commonly derived from reaction of an alkenyl
acylating agent with a polyamine, and a wide variety of linkages between the
two
moieties is possible beside the simple imide structure shown above, including
a variety
of amides and quaternary ammonium salts. In the aboveFormula (I), the amine
portion
is shown as an alkylene polyamine, although other aliphatic and aromatic mono-
and
polyamines may also be used. Also, a variety of modes of linkage of the R1
groups
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onto the imide structure are possible, including various cyclic linkages. The
ratio of
the carbonyl groups of the acylating agent to the nitrogen atoms of the amine
may be
1:0.5 to 1:3, and in other instances 1:1 to 1:2.75 or 1:1.5 to 1:2.5.
Succinimide
dispersants are more fully described in U.S. Patents 4,234,435 and 3,172,892
and in
EP 0355895.
[0056] In certain embodiments, the dispersant is prepared by a process
that
involves the presence of small amounts of chlorine or other halogen, as
described in
U.S. Patent 7,615,521 (see, e.g., col. 4, lines 18-60 and preparative example
A). Such
dispersants typically have some carbocyclic structures in the attachment of
the
hydrocarbyl substituent to the acidic or amidic "head" group. In other
embodiments,
the dispersant is prepared by a thermal process involving an "ene" reaction,
without
the use of any chlorine or other halogen, as described in U.S. Patent
7,615,521;
dispersants made in this manner are often derived from high vinylidene (i.e.
greater
than 50% terminal vinylidene) polyisobutylene(See col. 4, line 61 to col. 5,
line 30
and preparative example B). Such dispersants typically do not contain the
above-
described carbocyclic structures at the point of attachment. In certain
embodiments,
the dispersant is prepared by free radical catalyzed polymerization of high-
vinylidene
polyisobutylene with an ethylenically unsaturated acylating agent, as
described in
United States Patent 8,067,347.
[0057] Dispersants may be derived from, as the polyolefin, high
vinylidene
polyisobutylene, that is, having greater than 50, 70, or 75% terminal
vinylidene groups
(a and 13 isomers). In certain embodiments, the succinimide dispersant may be
prepared
by the direct alkylation route. In other embodiments it may comprise a mixture
of direct
alkylation and chlorine-route dispersants.
[0058] Suitable dispersants for use in the compositions of the present
invention
include succinimide dispersants. In one embodiment, the dispersant may be
present as a
single dispersant. In one embodiment, the dispersant may be present as a
mixture of two
or three different dispersants, wherein at least one may be a succinimide
dispersant.
[0059] The succinimide dispersant may be a derivative of an aliphatic
polyamine,
or mixtures thereof The aliphatic polyamine may be aliphatic polyamine such as
an
ethylenepolyamine, a propylenepolyamine, a butylenepolyamine, or mixtures
thereof. In
one embodiment, the aliphatic polyamine may be ethylenepolyamine. In one
embodiment
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the aliphatic polyamine may be selected from the group consisting of
ethylenediamine,
diethylenetriamine, triethylenetetramine,
tetraethylenepentamine,
pentaethylenehexamine, polyamine still bottoms, and mixtures thereof
[0060] The
succinimide dispersant may be a derivative of an aromatic amine, an
aromatic polyamine, or mixtures thereof The aromatic amine may be 4-
aminodiphenylamine (ADPA) (also known as N-phenylphenylenediamine),
derivatives of
ADPA (as described in United States Patent Publications 2011/0306528 and
2010/0298185), a nitroaniline, an aminocarbazole, an amino-indazolinone, an
aminopyrimidine, 4-(4-nitrophenylazo)aniline, or combinations thereof In one
embodiment, the dispersant is derivative of an aromatic amine wherein the
aromatic amine
has at least three non-continuous aromatic rings.
[0061] The
succinimide dispersant may be a derivative of a polyether amine or
polyether polyamine. Typical polyether amine compounds contain at least one
ether unit
and will be chain terminated with at least one amine moiety. The polyether
polyamines
can be based on polymers derived from C2-C6 epoxides such as ethylene oxide,
propylene
oxide, and butylene oxide. Examples of polyether polyamines are sold under the
Jeffamine0 brand and are commercially available from Hunstman Corporation
located in
Houston, Texas.
[0062] Another
class of ashless dispersant is high molecular weight esters.
These materials are similar to the above-described succinimides except that
they may
be seen as having been prepared by reaction of a hydrocarbyl acylating agent
and a
polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol.
Such
materials are described in more detail in U.S. Patent 3,381,022. Aromatic
succinate
esters may also be prepared as described in United States Patent Publication
2010/0286414.
[0063] A
succinic-based dispersant (succinimide, succinamide, succinic ester,
and mixtures thereof) may be formed by reacting maleic anhydride or a reactive
equivalent thereof, such as an acid or ester, with a hydrocarbon chain by any
method
such as those disclosed above (e.g., chlorine-based process or thermal
process). Other
acids or equivalents thereof may be used in place of the maleic anhydride.
These include
fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citaconic
anhydride, and
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cinnamic acid as well as other ethylenically unsaturated acids such as acrylic
or
methacrylic acid; and their reactive equivalents.
[0064] Another class of ashless dispersant is Mannich bases. These are
materials which are formed by the condensation of a higher molecular weight,
alkyl
substituted phenol, an alkylene polyamine, and an aldehyde such as
formaldehyde.
Such materials may have the general structure as represented by Formula (II)
0 H 0 H
CH2-NH-(R2NH)x-R2NHCH2
I
y.
'.
R1 R1
(II)
(including a variety of isomers and the like) and are described in more detail
in U.S.
Patent 3,634,515.
[0065] Another class of ashless dispersants include dispersants
comprising a
quaternary ammonium salt. Quaternary ammonium salts include the reaction
product of:
(i) a compound comprising at least one tertiary amino group; and (ii) a
quaternizing agent
suitable for converting the tertiary amino group of compound (i) to a
quaternary nitrogen.
Examples of suitable quaternary ammonium salts include (i) imide quaternary
ammonium
salts, (ii) Mannich quaternary ammonium salts, (iii) polyalkene substituted
amine
quaternary ammonium salts, (iv) amide quaternary ammonium salts, (v) ester
quaternary
ammonium salts, (vi) polyester quaternary ammonium salts, or (vii) any
combination
thereof.
[0066] These various types of quaternary ammonium salts may be prepared
in any
number of ways but generally are prepared by reacting a non-quaternized
nitrogen-
containing compound with a quaternizing agent. Each of the different types of
quaternary
ammonium salts described uses a different non-quaternized nitrogen-containing
compound in its preparation, but generally the non-quaternized nitrogen-
containing
compound contains a tertiary nitrogen capable of being quaternized (or a
primary or
secondary nitrogen atom that can be alkylated to a tertiary nitrogen that can
then be
quaternized) and a hydrocarbyl substituent group. The preparation and use of
quaternized
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ammonium dispersants is described in detail in United States Patent 7,951,211
and United
States Patent 7,906,470.
[0067] The dispersant may also be post-treated by conventional methods by
a
reaction with any of a variety of agents. Among these are boron compounds,
urea,
thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones,
carboxylic acids,
hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles,
epoxides, and
phosphorus compounds.
[0068] The dispersant may also exhibit basicity, as measured by Total
Base
Number (TBN). TBN may be determined by ASTM D2896. This will particularly be
the case if the dispersant is prepared with an amine, such as a polyamine, and
the amine
contains one or more amino groups that have not reacted with acidic groups of
the
dispersant. In some embodiments, the TBN of the dispersant may be 1 to 110, or
5 to
50, or 10 to 40 or 30 to 70. In some embodiments, however, the dispersant may
not
exhibit basicity (that is, have a TBN of 0 or nearly 0). In one embodiment the
dispersant has a TBN of zero as measured by D2896. Such could be the case if
no
basic nitrogen is present on the dispersant
[0069] The dispersant may be present at 0.01 wt % to 20 wt %, or 0.1 wt %
to 15
wt %, or 0.1 wt % to 10 wt %, or 0.5 wt % to 8 wt % , or 1.0 wt % to 6.5 wt %,
or 0.5 wt
% to 2.2 wt% of the lubricating composition.
Other Performance Additives
[0070] The compositions of the invention may optionally comprise one or
more
additional performance additives. These additional performance additives may
include
one or more metal deactivators, viscosity modifiers, detergents, friction
modifiers,
antiwear agents, corrosion inhibitors, dispersants (other than those of the
invention),
dispersant viscosity modifiers, extreme pressure agents, antioxidants, foam
inhibitors,
demulsifiers, pour point depressants, seal swelling agents, and any
combination or mixture
thereof Typically, fully-formulated lubricating oil will contain one or more
of these
performance additives, and often a package of multiple performance additives.
[0071] In one embodiment, the invention provides a lubricating
composition
further comprising an antiwear agent, a dispersant viscosity modifier, a
friction modifier,
a viscosity modifier, an antioxidant, an overbased detergent, a dispersant
(different from
that of the invention), or a combination thereof, where each of the additives
listed may be
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a mixture of two or more of that type of additive. In one embodiment, the
invention
provides a lubricating composition further comprising an antiwear agent, a
dispersant
viscosity modifier, a friction modifier, a viscosity modifier (typically an
olefin copolymer
such as an ethylene-propylene copolymer), an antioxidant (including phenolic
and aminic
antioxidants), an overbased detergent (including overbased sulfonates and
phenates), or a
combination thereof, where each of the additives listed may be a mixture of
two or more
of that type of additive.
[0072] Another additive is an antiwear agent. Examples of anti-wear
agents
include phosphorus-containing antiwear/extreme pressure agents such as metal
thiophosphates, phosphoric acid esters and salts thereof, phosphorus-
containing
carboxylic acids, esters, ethers, and amides, and phosphites. In certain
embodiments a
phosphorus antiwear agent may be present in an amount to deliver 0.01 to 0.2
or 0.015 to
0.15 or 0.02 to 0.1 or 0.025 to 0.08 percent phosphorus. Often the antiwear
agent is a zinc
dialkyldithiophosphate (ZDP).
[0073] Zinc dialkyldithiophosphates may be described as primary zinc
dialkyldithiophosphates or as secondary zinc dialkyldithiophosphates,
depending on the
structure of the alcohol used in its preparation. In some embodiments the
compositions of
the invention include primary zinc dialkyldithiophosphates. In some
embodiments the
compositions of the invention include secondary zinc dialkyldithiophosphates.
In some
embodiments the compositions of the invention include a mixture of primary and
secondary zinc dialkyldithiophosphates. In some embodiments component (b) is a
mixture
of primary and secondary zinc dialkyldithiophosphates where the ratio of
primary zinc
dialkyldithiophosphates to secondary zinc dialkyldithiophosphates (one a
weight basis) is
at least 1:1, or even at least 1:1.2, or even at least 1:1.5 or 1:2, or 1:10.
In some
embodiments, component (b) is a mixture of primary and secondary zinc
dialkyldithiophosphates that is at least 50 percent by weight primary, or even
at least 60,
70, 80, or even 90 percent by weight primary. In some embodiments component
(b) is
free of primary zinc dialkyldithiophosphates.
[0074] The phosphorus antiwear agent may be present at 0 wt % to 3 wt %,
or 0.1
wt % to 1.5 wt %, or 0.5 wt % to 0.9 wt % of the lubricating composition.
[0075] In one embodiment, the invention provides a lubricating
composition which
further comprises ashless antioxidant. Ashless antioxidants may comprise one
or more of
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arylamines, diarylamines, alkylated arylamines, alkylated diaryl amines,
phenols, hindered
phenols, sulfurized olefins, or mixtures thereof In one embodiment the
lubricating
composition includes an antioxidant, or mixtures thereof The antioxidant may
be present
at 0 wt % to 15 wt %, or 0.1 wt % to 10 wt %, or 0.5 wt % to 5 wt %, or 0.5 wt
% to 3 wt
%, or 0.3 wt % to 1.5 wt % of the lubricating composition.
[0076] The
diarylamine or alkylated diarylamine may be a phenyl-a-
naphthylamine (PANA), an alkylated diphenylamine, or an alkylated
phenylnapthylamine,
or mixtures thereof. The
alkylated diphenylamine may include di-nonylated
diphenylamine, nonyl diphenylamine, octyl diphenylamine, di-octylated
diphenylamine,
di-decylated diphenylamine, decyl diphenylamine and mixtures thereof In one
embodiment, the diphenylamine may include nonyl diphenylamine, dinonyl
diphenylamine, octyl diphenylamine, dioctyl diphenylamine, or mixtures thereof
In one
embodiment the alkylated diphenylamine may include nonyl diphenylamine, or
dinonyl
diphenylamine. The alkylated diarylamine may include octyl, di-octyl, nonyl,
di-nonyl,
decyl or di-decyl phenylnapthylamines.
[0077] The
diarylamine antioxidant of the invention may be present on a weight
basis of the lubrication composition at 0.1% to 10%, 0.35% to 5%, or even 0.5%
to 2%.
[0078] The
phenolic antioxidant may be a simple alkyl phenol, a hindered phenol,
or coupled phenolic compounds.
[0079] The
hindered phenol antioxidant often contains a secondary butyl and/or a
tertiary butyl group as a sterically hindering group. The phenol group may be
further
substituted with a hydrocarbyl group (typically linear or branched alkyl)
and/or a bridging
group linking to a second aromatic group. Examples of suitable hindered phenol
antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-
butylphenol, 4-ethyl-
2,6-di-tert-butylphenol, 4-propy1-2,6-di-tert-butylphenol or 4-buty1-2,6-di-
tert-
butylphenol, 4-dodecy1-2,6-di-tert-butylphenol, or butyl 3-(3,5-ditert-buty1-4-
hydroxyphenyl)propanoate. In one embodiment, the hindered phenol antioxidant
may be
an ester and may include, e.g., IrganoxTM L-135 from Ciba.
[0080] Coupled
phenols often contain two alkylphenols coupled with alkylene
groups to form bisphenol compounds. Examples of suitable coupled phenol
compounds
include 4,4'- methylene bis-(2,6-di-tert-butyl phenol), 4-methyl-2,6-di-tert-
butylphenol,
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2,2'-bis-(6-t-buty1-4-heptylphenol); 4,4'-bis(2,6-di-t-butyl phenol), 2,2'-
methylenebis(4-
methy1-6-t-butylphenol), and 2,2'-methylene bis(4-ethyl-6-t-butylphenol).
[0081] Phenols of the invention also include polyhydric aromatic
compounds and
their derivatives. Examples of suitable polyhydric aromatic compounds include
esters and
amides of gallic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid,
1,4-
dihydroxy-2-naphthoic acid, 3,5-dihydroxynaphthoic acid, 3,7-dihydroxy
naphthoic acid,
and mixtures thereof.
[0082] In one embodiment, the phenolic antioxidant comprises a hindered
phenol.
In another embodiment the hindered phenol is derived from 2,6-ditertbutyl
phenol.
[0083] In one embodiment, the lubricating composition of the invention
comprises
a phenolic antioxidant in a range of 0.01 wt % to 5 wt %, or 0.1 wt % to 4 wt
%, or 0.2 wt
% to 3 wt %, or 0.5 wt % to 2 wt % of the lubricating composition.
[0084] Sulfurized olefins are well known commercial materials, and those
which
are substantially nitrogen-free, that is, not containing nitrogen
functionality, are readily
available. The olefinic compounds which may be sulfurized are diverse in
nature. They
contain at least one olefinic double bond, which is defined as a non-aromatic
double bond;
that is, one connecting two aliphatic carbon atoms. These materials generally
have sulfide
linkages having 1 to 10 sulfur atoms, for instance, 1 to 4, or 1 or 2.
[0085] Ashless antioxidants may be used separately or in combination. In
one
embodiment of the invention, two or more different antioxidants are used in
combination,
such that there is at least 0.1 weight percent of each of the at least two
antioxidants and
wherein the combined amount of the ashless antioxidants is 0.5 to 5 weight
percent. In one
embodiment, there may be at least 0.25 to 3 weight percent of each ashless
antioxidant.
[0086] In one embodiment, the invention provides a lubricating
composition
further comprising a molybdenum compound. The molybdenum compound may be
selected from the group consisting of molybdenum dialkyldithiophosphates,
molybdenum
dithiocarbamates, amine salts of molybdenum compounds, and mixtures thereof.
The
molybdenum compound may provide the lubricating composition with 0 to 1000
ppm, or
to 1000 ppm, or 10 to 750 ppm, or 5 ppm to 300 ppm, or 20 ppm to 250 ppm of
molybdenum.
[0087] In one embodiment, the lubricating composition of the invention
further
comprises a dispersant viscosity modifier. The dispersant viscosity modifier
may be
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present at 0 wt % to 5 wt %, or 0 wt % to 4 wt %, or 0.05 wt % to 2 wt % of
the lubricating
composition.
[0088]
Suitable dispersant viscosity modifiers include functionalized polyolefins,
for example, ethylene-propylene copolymers that have been functionalized with
an
acylating agent such as maleic anhydride and an amine; polymethacrylates
functionalized
with an amine, or esterified styrene-maleic anhydride copolymers reacted with
an amine.
More detailed description of dispersant viscosity modifiers are disclosed in
International
Publication W02006/015130 or U.S. Patents 4,863,623; 6,107,257; 6,107,258; and
6,117,825. In one embodiment, the dispersant viscosity modifier may include
those
described in U.S. Patent 4,863,623 (see column 2, line 15 to column 3, line
52) or in
International Publication W02006/015130 (see page 2, paragraph [0008] and
preparative
examples are described at paragraphs [0065] to [0073]).
[0089] In one
embodiment, the invention provides a lubricating composition
further comprising a metal-containing detergent. The metal-containing
detergent may be
an overbased detergent. Overbased detergents otherwise referred to as
overbased or
superbased salts are characterized by a metal content in excess of that which
would be
necessary for neutralization according to the stoichiometry of the metal and
the particular
acidic organic compound reacted with the metal. The overbased detergent may be
selected
from the group consisting of non-sulfur containing phenates, sulfur containing
phenates,
sulfonates, salixarates, salicylates, and mixtures thereof
[0090] The
metal-containing detergent may also include "hybrid" detergents
formed with mixed surfactant systems including phenate and/or sulfonate
components, e.g.
phenate/salicylates, sulfonate/phenates,
sulfonate/salicylates,
sulfonates/phenates/salicylates, as described, for example, in US Patents
6,429,178;
6,429,179; 6,153,565; and 6,281,179. Where, for example, a hybrid
sulfonate/phenate
detergent is employed, the hybrid detergent would be considered equivalent to
amounts of
distinct phenate and sulfonate detergents introducing like amounts of phenate
and
sulfonate soaps, respectively.
[0091] The
overbased metal-containing detergent may be sodium salts, calcium
salts, magnesium salts, or mixtures thereof of the phenates, sulfur-containing
phenates,
sulfonates, salixarates and salicylates. Overbased phenates and salicylates
typically have
a total base number of 180 to 450 TBN. Overbased sulfonates typically have a
total base
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number of 250 to 600, or 300 to 500. Overbased detergents are known in the
art. In one
embodiment, the sulfonate detergent may be predominantly a linear alkylbenzene
sulfonate detergent having a metal ratio of at least 8 as is described in
paragraphs [0026]
to [0037] of US Patent Publication 2005065045 (and granted as US 7,407,919).
The linear
alkylbenzene sulfonate detergent may be particularly useful for assisting in
improving fuel
economy. The linear alkyl group may be attached to the benzene ring anywhere
along the
linear chain of the alkyl group, but often in the 2, 3 or 4 position of the
linear chain, and
in some instances, predominantly in the 2 position, resulting in the linear
alkylbenzene
sulfonate detergent. Overbased detergents are known in the art. The overbased
detergent
may be present at 0 wt % to 15 wt %, or 0.1 wt % to 10 wt %, or 0.2 wt % to 8
wt %, or
0.2 wt % to 3 wt %. For example, in a heavy duty diesel engine, the detergent
may be
present at 2 wt % to 3 wt % of the lubricating composition. For a passenger
car engine,
the detergent may be present at 0.2 wt % to 1 wt % of the lubricating
composition.
[0092] Metal-containing detergents contribute sulfated ash to a
lubricating
composition. Sulfated ash may be determined by ASTM D874. In one embodiment,
the
lubricating composition of the invention comprises a metal-containing
detergent in an
amount to deliver at least 0.4 weight percent sulfated ash to the total
composition. In
another embodiment, the metal-containing detergent is present in an amount to
deliver at
least 0.6 weight percent sulfated ash, or at least 0.75 weight percent
sulfated ash, or even
at least 0.9 weight percent sulfated ash to the lubricating composition.
[0093] In one embodiment, the invention provides a lubricating
composition
further comprising a friction modifier. Examples of friction modifiers include
long chain
fatty acid derivatives of amines, fatty esters, or epoxides; fatty
imidazolines such as
condensation products of carboxylic acids and polyalkylene-polyamines; amine
salts of
alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; or
fatty alkyl
tartramides. The term fatty, as used herein, can mean having a C8-22 linear
alkyl group.
[0094] Friction modifiers may also encompass materials such as sulfurized
fatty
compounds and olefins, molybdenum dialkyldithiophosphates, molybdenum
dithiocarbamates, sunflower oil or monoester of a polyol and an aliphatic
carboxylic acid.
[0095] In one embodiment the friction modifier may be selected from the
group
consisting of long chain fatty acid derivatives of amines, long chain fatty
esters, or long
chain fatty epoxides; fatty imidazolines; amine salts of alkylphosphoric
acids; fatty alkyl
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tartrates; fatty alkyl tartrimides; and fatty alkyl tartramides. The friction
modifier may be
present at 0 wt % to 6 wt %, or 0.05 wt % to 4 wt %, or 0.1 wt % to 2 wt % of
the lubricating
composition.
[0096] In one embodiment, the friction modifier may be a long chain fatty
acid
ester. In another embodiment the long chain fatty acid ester may be a mono-
ester or a
diester or a mixture thereof, and in another embodiment the long chain fatty
acid ester may
be a triglyceride.
[0097] Other performance additives such as corrosion inhibitors include
those
described in paragraphs 5 to 8 of US Application US05/038319, published as
W02006/047486, octyl octanamide, condensation products of dodecenyl succinic
acid or
anhydride and a fatty acid such as oleic acid with a polyamine. In one
embodiment, the
corrosion inhibitors include the Synalox0 (a registered trademark of The Dow
Chemical
Company) corrosion inhibitor. The Synalox0 corrosion inhibitor may be a
homopolymer
or copolymer of propylene oxide. The Synalox0 corrosion inhibitor is described
in more
detail in a product brochure with Form No. 118-01453-0702 AMS, published by
The Dow
Chemical Company. The product brochure is entitled "SYNALOX Lubricants, High-
Performance Polyglycols for Demanding Applications."
[0098] The lubricating composition may further include metal
deactivators,
including derivatives of benzotriazoles (typically tolyltriazole),
dimercaptothiadiazole
derivatives, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, or
2-
alkyldithiobenzothiazoles; foam inhibitors, including copolymers of ethyl
acrylate and 2-
ethylhexylacrylate and copolymers of ethyl acrylate and 2-ethylhexylacrylate
and vinyl
acetate; demulsifiers including trialkyl phosphates, polyethylene glycols,
polyethylene
oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers;
and pour
point depressants, including esters of maleic anhydride-styrene,
polymethacrylates,
polyacrylates or polyacrylamides.
[0099] Pour point depressants that may be useful in the compositions of
the
invention further include polyalphaolefins, esters of maleic anhydride-
styrene,
poly(meth)acrylates, polyacrylates or polyacrylamides.
[0100] In different embodiments the lubricating composition may have a
composition as described in the following table:
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Additive Embodiments (wt %)
A B C
Dispersant of the invention 0.05 to 12 0.75 to 8 0.5 to 6
Antioxidant 0.05 to 1 0.2 to 3 0.5 to 2
Dispersant Viscosity Modifier 0 or 0 or 0.05 to 2
0.05 to 5 0.05 to 4
Overbased Detergent 0 or 0.1 to 10 0.2 to 8
0.05 to 15
Antiwear Agent 0 or 0.1 to 10 0.3 to 5
0.05 to 15
Friction Modifier 0 or 0.05 to 4 0.1 to 2
0.05 to 6
Viscosity Modifier 0 or 0.5 to 8 1 to 6
0.05 to 10
Any Other Performance Additive 0 or 0 or 0 or
0.05 to 10 0.05 to 8 0.05 to 6
Oil of Lubricating Viscosity Balance to Balance to Balance to
100% 100% 100%
[0101] The present invention provides a surprising ability to prevent
damage to an
engine in operation due to pre-ignition events resulting from direct gasoline
injection into
the combustion chamber. This is accomplished while maintaining fuel economy
performance, low sulfated ash levels, and other limitations, required by
increasingly
stringent government regulations.
Industrial Application
[0102] As described above, the invention provides for a method of
lubricating an
internal combustion engine comprising supplying to the internal combustion
engine a
lubricating composition as disclosed herein. Generally, the lubricant is added
to the
lubricating system of the internal combustion engine, which then delivers the
lubricating
composition to the critical parts of the engine, during its operation, that
require lubrication.
[0103] The lubricating compositions described above may be utilized in an
internal
combustion engine. The engine components may have a surface of steel or
aluminum
(typically a surface of steel), and may also be coated for example with a
diamond-like
carbon (DLC) coating.
[0104] An aluminum surface may be comprised of an aluminum alloy that may
be
a eutectic or hyper-eutectic aluminum alloy (such as those derived from
aluminum
silicates, aluminum oxides, or other ceramic materials). The aluminum surface
may be
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present on a cylinder bore, cylinder block, or piston ring having an aluminum
alloy, or
aluminum composite.
[0105] The internal combustion engine may be fitted with an emission
control
system or a turbocharger. Examples of the emission control system include
diesel
particulate filters (DPF), or systems employing selective catalytic reduction
(SCR).
[0106] The internal combustion engine of the present invention is
distinct from a
gas turbine. In an internal combustion engine, individual combustion events
translate from
a linear reciprocating force into a rotational torque through the rod and
crankshaft. In
contrast, in a gas turbine (which may also be referred to as a jet engine) a
continuous
combustion process generates a rotational torque continuously without
translation, and can
also develop thrust at the exhaust outlet. These differences in operation
conditions of a
gas turbine and internal combustion engine result in different operating
environments and
stresses.
[0107] The lubricant composition for an internal combustion engine may be
suitable for any engine lubricant irrespective of the sulfur, phosphorus or
sulfated ash
(ASTM D-874) content. The sulfur content of the engine oil lubricant may be 1
wt % or
less, or 0.8 wt % or less, or 0.5 wt % or less, or 0.3 wt % or less. In one
embodiment, the
sulfur content may be in the range of 0.001 wt % to 0.5 wt %, or 0.01 wt % to
0.3 wt %.
The phosphorus content may be 0.2 wt % or less, or 0.12 wt % or less, or 0.1
wt % or less,
or 0.085 wt % or less, or 0.08 wt % or less, or even 0.06 wt % or less, 0.055
wt % or less,
or 0.05 wt % or less. In one embodiment the phosphorus content may be 100 ppm
to 1000
ppm, or 200 ppm to 600 ppm. The total sulfated ash content may be 2 wt % or
less, or 1.5
wt % or less, or 1.1 wt % or less, or 1 wt % or less, or 0.8 wt % or less, or
0.5 wt % or less,
or 0.4 wt % or less. In one embodiment, the sulfated ash content may be 0.05
wt % to 0.9
wt %, or 0.1 wt % to 0.2 wt % or to 0.45 wt %.
[0108] In one embodiment, the lubricating composition may be an engine
oil,
wherein the lubricating composition may be characterized as having at least
one of (i) a
sulfur content of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % or
less, (iii) a
sulfated ash content of 1.5 wt % or less, or combinations thereof
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EXAMPLES
[0109] The invention will be further illustrated by the following
examples, which
set forth particularly advantageous embodiments. While the examples are
provided to
illustrate the invention, they are not intended to limit it.
Lubricating Compositions
[0110] A series of 5W-20 engine lubricants in Group II base oil of
lubricating
viscosity are prepared containing the ashless dispersant additives described
above as well
as conventional additives including polymeric viscosity modifier, overbased
detergents,
antioxidants (combination of phenolic ester and diarylamine), zinc
dialkyldithiophosphate
(ZDDP), as well as other performance additives as set forth in Table 1. The
phosphorus,
sulfur and ash contents of each of the examples are also presented in the
Table in part to
show that each example has a similar amount of these materials and so provide
a proper
comparison between the comparative and invention examples.
Table 1 - Lubricating Oil Composition Formulations
COMP INV EX5
INV EX6
INV EX2 INV EX3 INV EX4
EX1
Group III Base Oil Balance to = 100%
Dispersant 12 0.8 1.2 2.0 3.6 2.4
Dispersant 23 4.6
Ashless Antioxidant4 2.0 0.725 1.4 2.0 2.18 4.0
Ca Detergent' 0.75 0.37 1.13 0.06 1.11 0.74
Ca Phenate6 0 0 0 1.4 0 0
Na Sulfonate 0.18 0.09 0 0 0.26 0.18
ZDDP 0.76 0.4 0.7 0.45 1.1 0.76
VI Improver 1.0 1.0 2.1 1.1 1.0 0.55
Additional Additives' 1.0 0.85 1.4 0.58 2.1 2.0
%Phosphorus 0.076 0.038 0.060 0.046 0.11 0.076
%Calcium 0.168 0.084 0.234 0.123 0.251 0.168
%Sodium 0.049 0.024 0 0 0.073 0.049
%Molybdenum (ppm) 0 46 0 0 140 90
TB N 10.8 3.84 7.75 6.1 11.5 10.8
%Ash 0.9 0.44 0.9 0.50 1.31 0.88
1 - All amounts shown above are in weight percent and are on an oil-free basis
unless
otherwise noted
2 - PIBsuccinimide Dispersant, prepared from 2000 Mn polyisobutylene,
sucinated in a
conventional chlorine process to form a "mid-succan" with 1.3-1.6 succination
ratio, and
aminated with polyethylene polyamines; TBN = 28
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3 - PIBsuccinimide Dispersant, prepared from 1500 Mn high vinylidene
polyisobutylene,
thermally succinated, and aminated with polyethylene polyamines; TBN = 20
4 - Combination of diarylamine and hindered phenol antioxidants
- Ca Detergent is one or more overbased calcium alkylbenzene sulfonic acid
with TBN
at least 300 and metal ratio at least 10
6- Ca Phenate is 145 TBN calcium phenate
7 - The Additional Additives used in the examples includes a dispersant, and
an antifoam
agent, and includes some amount of diluent oil. The same Additive package is
used in
each of the examples
Table 2 - Lubricating Oil Composition Formulations (5W-30)1
EX7 EX8 EX9 EX10 EX11
Group III Base Oil Balance to = 100%
Dispersant2 2 2 2.7 2.7 2.7
Hindered phenol 0.25 0.25 0.25 0.5 0.5
Diarylamine 0.5 0.5 0.5 0.9 0.9
Sulfurized Olefin 0.1 0.9 0.1 0.2 0.2
Ca Detergent3 2.78 2.78 2.78 2.78 2.78
ZDDP 0.32 0.32 0.32 0.32 0.77
VI Improver 0.6 0.6 0.6 0.6 0.6
Additional Additives4 0.46 0.46 0.73 0.73 0.73
%Phosphorus 0.03 0.03 0.03 0.03 0.076
%Calcium 0.71 0.71 0.71 0.71 0.71
1 - All amounts shown above are in weight percent and are on an oil-free basis
unless
otherwise noted.
2 - Polyisobutylene (Mn 2300) based succinimide dispersant prepared with
ethylene
polyamines (TBN = 28)
3 - Ca Detergent is one or more overbased calcium alkylbenzene sulfonic acid
with TBN
at least 300 and metal ratio at least 10
4 - The Additional Additives used in the examples include friction modifiers,
pourpoint
depressants, anti-foam agents, corrosion inhibitors, and includes some amount
of diluent
oil.
Testing
[0111] Low Speed Pre-Ignition events are measured in two engines, a Ford
2.0L
Ecoboost engine and a GM 2.0L Ecotec. Both of these engines are turbocharged
gasoline
direct injection (GDI) engines. The Ford Ecoboost engine is operated in two
stages. In the
first stage, the engine is operated at 1500 rpm and 14.4 bar break mean
effective pressure
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(BMEP). During the second stage, the engine is operated at 1750 rpm and 17.0
bar BMEP.
The engine is run for 25,000 combustion cycles in each stage, and LSPI events
are counted.
[0112] The GM Ecotec engine is operated at 2000 rpm and 22.0 bar BMEP
with
an oil sump temperature of 100oC. The test consists of nine phases of 15,000
combustion
cycles with each phase separated by an idle period. Thus combustion events are
counted
over 135,000 combustion cycles.
[0113] LSPI events are determined by monitoring peak cylinder pressure
(PP) and
mass fraction burn (MFB) of the fuel charge in the cylinder. When both
criteria are met, it
is determined that an LSPI event has occurred. The threshold for peak cylinder
pressure is
typically 9,000 to 10,000 kPa. The threshold for MFB is typically such that at
least 2% of
the fuel charge is burned late, i.e. 5.5 degrees After Top Dead Center (ATDC).
LSPI events
can be reported as events per 100,000 combustion cycles, events per cycle,
and/or
combustion cycles per event.
Table 4 ¨ GM Ecotec LSPI Testing
EX7 EX8 EX9 EX10 EX11
PP Events 44 18 39 26 22
MFB Events 46 21 42 29 25
Total Events 43 18 39 26 22
Total Cycles 135,000 135,000 135,000 135,000 135,000
Ave. PP 18,800 18,900 17,600 18,400 19,300
Events per 100,000
31.8 13.3 28.9 19.2 16.3
cycles
Cycles per event 3140 7500 3461 5192 6136
[0114] The data indicates that LSPI events are reduced as the treat rate
of
dispersant is reduced.
[0115] It is known that some of the materials described above may
interact in the
final formulation, so that the components of the final formulation may be
different from
those that are initially added. The products formed thereby, including the
products formed
upon employing lubricant composition of the present invention in its intended
use, may
not be susceptible of easy description. Nevertheless, all such modifications
and reaction
products are included within the scope of the present invention; the present
invention
encompasses lubricant composition prepared by admixing the components
described
above.
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[0116] Each of the documents referred to above is incorporated herein by
reference, as is the priority document and all related applications, if any,
which this
application claims the benefit of. Except in the Examples, or where otherwise
explicitly
indicated, all numerical quantities in this description specifying amounts of
materials,
reaction conditions, molecular weights, number of carbon atoms, and the like,
are to be
understood as modified by the word "about." Unless otherwise indicated, each
chemical
or composition referred to herein should be interpreted as being a commercial
grade
material which may contain the isomers, by-products, derivatives, and other
such materials
which are normally understood to be present in the commercial grade. However,
the
amount of each chemical component is presented exclusive of any solvent or
diluent oil,
which may be customarily present in the commercial material, unless otherwise
indicated.
It is to be understood that the upper and lower amount, range, and ratio
limits set forth
herein may be independently combined. Similarly, the ranges and amounts for
each
element of the invention may be used together with ranges or amounts for any
of the other
elements.
[0117] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl
group"
is used in its ordinary sense, which is well-known to those skilled in the
art. Specifically,
it refers to a group having a carbon atom directly attached to the remainder
of the molecule
and having predominantly hydrocarbon character. Examples of hydrocarbyl groups
include:
(i) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),
alicyclic (e.g.,
cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and
alicyclic-
substituted aromatic substituents, as well as cyclic substituents wherein the
ring is
completed through another portion of the molecule (e.g., two substituents
together
form a ring);
(ii) substituted hydrocarbon substituents, that is, substituents containing
non-
hydrocarbon groups which, in the context of this invention, do not alter the
predominantly hydrocarbon nature of the substituent (e.g., halo (especially
chloro
and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and
sulphoxy);
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(iii) hetero substituents, that is, substituents which, while having a
predominantly
hydrocarbon character, in the context of this invention, contain other than
carbon
in a ring or chain otherwise composed of carbon atoms.
[0118] Heteroatoms include sulfur, oxygen, nitrogen, and encompass
substituents
as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two,
preferably no more
than one, non-hydrocarbon substituent will be present for every ten carbon
atoms in the
hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in
the
hydro carbyl group.
[0119] While the invention has been explained in relation to its
preferred
embodiments, it is to be understood that various modifications thereof will
become
apparent to those skilled in the art upon reading the specification.
Therefore, it is to be
understood that the invention disclosed herein is intended to cover such
modifications as
fall within the scope of the appended claims.
