Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICATING OIL COMPOSITIONS CONTAINING NON-SULFUR-
PHOSPHORUS CONTAINING ZINC COMPOUNDS AND METHOD FOR
PREVENTING OR REDUCING LOW SPEED PRE-IGNITION IN DIRECT
INJECTED SPARK-IGNITED ENGINES
FIELD OF THE INVENTION
This disclosure relates to a lubricant composition for a direct injected,
boosted, spark ignited
internal combustion engine that contains at least one non-sulfur-phosphorus
containing zinc
compound. This disclosure also relates to a method for preventing or reducing
low speed pre-
ignition in an engine lubricated with a formulated oil. The formulated oil has
a composition
comprising at least one oil soluble or oil dispersible non-sulfur-phosphorus
zinc compound.
BACKGROUND OF THE INVENTION
One of the leading theories surrounding the cause of low speed pre-ignition
(LSPI) is at least
in part, due to auto-ignition of engine oil droplets that enter the engine
combustion chamber
from the piston crevice under high pressure, during periods in which the
engine is operating at
low speeds, and compression stroke time is longest (Amann et al. SAE 2012-01-
1140).
Although some engine knocking and pre-ignition problems can be and are being
resolved
through the use of new engine technology, such as electronic controls and
knock sensors, and
through the optimization of engine operating conditions, there is a role for
lubricating oil
compositions which can decrease or prevent the problem. The present inventors
have
discovered a solution for addressing the problem of LSPI through the use of
non-sulfur-
phosphorus zinc containing additives.
SUMMARY OF THE INVENTION
In an aspect, the present disclosure provides a method for preventing or
reducing low speed
pre-ignition in a direct injected, boosted, spark ignited internal combustion
engine, said method
comprising the step of lubricating the crankcase of the engine with a
lubricating oil composition
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comprising from about 200 to about 3000 ppm of zinc metal from at least one
non-sulfur-
phosphorus containing zinc compound, based on the total weight of the
lubricating oil.
For example, the non-sulfur-phosphorus containing zinc compound is a zinc
alkoxide or
thiolate compound, zinc aryloxide or arylthiolate compound, colloidal
dispersion of zinc oxide,
stable colloidal zinc suspension, zinc amido compound, zinc acetylacetonate
compound, zinc
.. carboxylate, zinc alkylhydroxybenzoate, zinc arylsulfonate, zinc sulfurized
phenate, zinc
dithiocarbamato complex, zinc salen complex, bimetallic zinc complex, zinc
phosphate ester,
zinc phospinate, zinc phosphinite complex, zinc pyridyl complex, zinc
polypyridyl complex,
zinc quinolinolato complex, zinc succinimide.
In yet another aspect, the present disclosure provides a lubricating engine
oil composition for
a direct injected, boosted, spark ignited internal combustion engine
comprising from about 200
to about 3000 ppm of zinc metal from at least one non-sulfur-phosphorus
containing zinc
compound, based on the total weight of the lubricating oil.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
The term "boosting" is used throughout the specification. Boosting refers to
running an engine
at higher intake pressures than in naturally aspirated engines. A boosted
condition can be
reached by use of a turbocharger (driven by exhaust) or a supercharger (driven
by the engine).
Using smaller engines that provide higher power densities has allowed engine
manufacturers
to provide excellent performance while reducing frictional and pumping losses.
This is
accomplished by increasing boost pressures with the use of turbochargers or
mechanical
superchargers, and by down-speeding the engine by using higher transmission
gear ratios
allowed by higher torque generation at lower engine speeds. However, higher
torque at lower
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engine speeds has been found to cause random pre-ignition in engines at low
speeds, a
phenomenon known as Low Speed Pre-Ignition, or LSPI, resulting in extremely
high cylinder
peak pressures, which can lead to catastrophic engine failure. The possibility
of LSPI prevents
engine manufacturers from fully optimizing engine torque at lower engine speed
in such
smaller, high-output engines.
Throughout the specification and claims the expression oil soluble or
dispersible is used. By
oil soluble or dispersible is meant that an amount needed to provide the
desired level of activity
or performance can be incorporated by being dissolved, dispersed or suspended
in an oil of
lubricating viscosity. Usually, this means that at least about 0.001% by
weight of the material
can be incorporated in a lubricating oil composition. For a further discussion
of the terms oil
soluble and dispersible, particularly "stably dispersible", see U.S. Pat. No.
4,320,019 which is
expressly incorporated herein by reference for relevant teachings in this
regard.
The term "sulfated ash" as used herein refers to the non-combustible residue
resulting from
detergents and metallic additives in lubricating oil. Sulfated ash may be
determined using
ASTM Test D874.
The term "Total Base Number" or "TBN" as used herein refers to the amount of
base equivalent
to milligrams of KOH in one gram of sample. Thus, higher TBN numbers reflect
more alkaline
products, and therefore a greater alkalinity. TBN was determined using ASTM D
2896 test.
Unless otherwise specified, all percentages are in weight percent.
In general, the level of sulfur in the lubricating oil compositions of the
present invention is less
than or equal to about 0.7 wt. %, based on the total weight of the lubricating
oil composition,
e.g., a level of sulfur of about 0.01 wt. % to about 0.70 wt. %, 0.01 to 0.6
wt.%, 0.01 to 0.5
wt.%, 0.01 to 0.4 wt.%, 0.01 to 0.3 wt.%, 0.01 to 0.2 wt.%, 0.01 wt. % to 0.10
wt. %. In one
embodiment, the level of sulfur in the lubricating oil compositions of the
present invention is
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less than or equal to about 0.60 wt. %, less than or equal to about 0.50 wt.
%, less than or equal
to about 0.40 wt. %, less than or equal to about 0.30 wt. %, less than or
equal to about 0.20 wt.
%, less than or equal to about 0.10 wt. % based on the total weight of the
lubricating oil
composition.
In one embodiment, the levels of phosphorus in the lubricating oil
compositions of the present
invention is less than or equal to about 0.12 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.12
wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
invention is less than or equal to about 0.11 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.11
wt. %. In one
.. embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
invention is less than or equal to about 0.10 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.10
wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
invention is less than or equal to about 0.09 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.09
wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
invention is less than or equal to about 0.08 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.08
wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
.. invention is less than or equal to about 0.07 wt. %, based on the total
weight of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.07
wt. %. In one
embodiment, the levels of phosphorus in the lubricating oil compositions of
the present
invention is less than or equal to about 0.05 wt. %, based on the total weight
of the lubricating
oil composition, e.g., a level of phosphorus of about 0.01 wt. % to about 0.05
wt. %.
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oil compositions of
the present invention is less than or equal to about 1.60 wt. % as determined
by ASTM D 874,
e.g., a level of sulfated ash of from about 0.10 to about 1.60 wt. % as
determined by ASTM D
874. In one embodiment, the level of sulfated ash produced by the lubricating
oil compositions
of the present invention is less than or equal to about 1.00 wt. % as
determined by ASTM D
874, e.g., a level of sulfated ash of from about 0.10 to about 1.00 wt. % as
determined by ASTM
D 874. In one embodiment, the level of sulfated ash produced by the
lubricating oil
compositions of the present invention is less than or equal to about 0.80 wt.
% as determined
by ASTM D 874, e.g., a level of sulfated ash of from about 0.10 to about 0.80
wt. % as
determined by ASTM D 874. In one embodiment, the level of sulfated ash
produced by the
lubricating oil compositions of the present invention is less than or equal to
about 0.60 wt. %
as determined by ASTM D 874, e.g., a level of sulfated ash of from about 0.10
to about 0.60
wt. % as determined by ASTM D 874.
Suitably, the present lubricating oil composition may have a total base number
(TBN) of 4 to
15 mg KOH/g (e.g., 5 to 12 mg KOH/g, 6 to 12 mg KOH/g, or 8 to 12 mg KOH/g).
.. Low Speed Pre-Ignition is most likely to occur in direct-injected, boosted
(turbocharged or
supercharged), spark-ignited (gasoline) internal combustion engines that, in
operation, generate
a break mean effective pressure level of greater than about 15 bar (peak
torque), such as at least
about 18 bar, particularly at least about 20 bar at engine speeds of from
about 1500 to about
2500 rotations per minute (rpm), such as at engine speeds of from about 1500
to about 2000
rpm. As used herein, break mean effective pressure (BMEP) is defined as the
work
accomplished during one engine cycle, divided by the engine swept volume; the
engine torque
normalized by engine displacement. The word "brake" denotes the actual
torque/power
available at the engine flywheel, as measured on a dynamometer. Thus, BMEP is
a measure of
the useful power output of the engine.
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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.
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 15 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 4 LSPI events per 100,000 combustion
events, less than
.. 3 LSPI events per 100,000 combustion events, less than 2 LSPI events per
100,000 combustion
events, less than 1 LSPI event per 100,000 combustion events,or there may be 0
LSPI events
per 100,000 combustion events.
Therefore, in an aspect the present disclosure provides a method for
preventing or reducing
low speed pre-ignition in a direct injected, boosted, spark ignited internal
combustion engine,
.. said method comprising the step of lubricating the crankcase of the engine
with a lubricating
oil composition comprising at least one non-sulfur-phosphorus containing zinc
compound. In
one embodiment, the amount of zinc metal from the at least one non-sulfur-
phosphorus
containing zinc compound is from about 200 to about 3000 ppm, or from about
250 to about
3000 ppm, from about 300 to about 3000 ppm, from about 350 to about 3000 ppm,
from about
400 ppm to about 3000 ppm, from about 500 to about 3000 ppm, from about 600 to
about 3000
ppm, from about 700 to about 3000 ppm, from about 900 to about 3000, from
about 950 to
about 3000 ppm, from about 1000 to 3000 ppm, from about 1050 to about 3000
ppm, from
about 1100 to about 3000 ppm, from about 1200 to about 3000 ppm, from about
1300 to about
3000 ppm, from about 1400 to about 3000 ppm, or from about 1400 to 3000 ppm.
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In one embodiment, the total amount of zinc in the formulation including the
metal from the at
least one non-sulfur-phosphorus containing zinc compound is from about 700 to
about 4000
ppm, or from about 800 to about 4000 ppm, from about 900 to about 4000, from
about 950 to
about 4000 ppm, from about 1000 to 4000 ppm, from about 1050 to about 4000
ppm, from
about 1100 to about 4000 ppm, from about 1200 to about 4000 ppm, from about
1300 to about
4000 ppm, from about 1400 to about 4000 ppm, or from about 1400 to 4000 ppm.
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,
or at least 60 percent, or at least 70 percent, or at least 80 percent, or at
least 90 percent, or at
least 95 percent, compared to an oil that does not contain the at least one
non-sulfur-phosphorus
containing zinc compound.
In another aspect, the present disclosure provides a method for reducing the
severity of low
speed pre-ignition events in a direct injected, boosted, spark ignited
internal combustion
engine, said method comprising the step of lubricating the crankcase of the
engine with a
lubricating oil composition comprising at least one least one non-sulfur-
phosphorus containing
zinc compound. LSPI events are determined by monitoring peak cylinder pressure
(PP) and
mass fraction burn (MFB) of the fuel charge in the cylinder. When either or
both criteria are
met, it can be said that an LSPI event has occurred. The threshold for peak
cylinder pressure
varies by test, but is typically 4-5 standard deviations above the average
cylinder
pressure. Likewise, the MFB threshold is typically 4-5 standard deviations
earlier than the
average MFB (represented in crank angle degrees). LSPI events can be reported
as average
events per test, events per 100,000 combustion cycles, events per cycle,
and/or combustion
cycles per event. In one embodiment, the number of LSPI events where both
MFB02 and Peak
Pressure (PP) Requirements that were greater than 90 bar of pressure is less
than 5 events, less
than 4 events, less than 3 events, less than 2 events, or less than 1 event.
In one embodiment,
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the number of LSPI events that were greater than 90 bar was zero events, or in
other words
completely suppressed LSPI events greater than 90 bar. In one embodiment, the
number of
LSPI events where both MFB02 and Peak Pressure (PP) Requirements that were
greater than
100 bar of pressure is less than 5 events, less than 4 events, less than 3
events, less than 2
events, or less than 1 event. In one embodiment, the number of LSPI events
that were greater
than 100 bar was zero events, or in other words completely suppressed LSPI
events greater
than 100 bar. In one embodiment, the number of LSPI events where both MFB02
and Peak
Pressure (PP) Requirements that were greater than 110 bar of pressure is less
than 5 events,
less than 4 events, less than 3 events, less than 2 events, or less than 1
event. In one
embodiment, the number of LSPI events that were greater than 110 bar was zero
events, or in
other words completely suppressed LSPI events greater than 110 bar. For
example, the number
of LSPI events where both MFB02 and Peak Pressure (PP) Requirements that were
greater
than 120 bar of pressure is less than 5 events, less than 4 events, less than
3 events, less than 2
events, or less than 1 event. In one embodiment, the number of LSPI events
that were greater
than 120 bar was zero events, or in other words completely suppressed very
severe LSPI events
(i.e., events greater than 120 bar).
It has now been found that the occurrence of LSPI in engines susceptible to
the occurrence of
LSPI can be reduced by lubricating such engines with lubricating oil
compositions containing
a non-sulfur-phosphorus containing zinc compound.
The disclosure further provides the method described herein in which the
engine is fueled with
a liquid hydrocarbon fuel, a liquid nonhydrocarbon fuel, or mixtures thereof.
The disclosure further provides the method described herein in which the
engine is fueled by
natural gas, liquefied petroleum gas (LPG), compressed natural gas (CNG), or
mixtures
thereof
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Lubricating oil compositions suitable for use as passenger car motor oils
conventionally
comprise a major amount of oil of lubricating viscosity and minor amounts of
performance
enhancing additives, including ash-containing compounds. Conveniently, zinc is
introduced
into the lubricating oil compositions used in the practice of the present
disclosure by one or
more non-sulfur-phosphorus containing zinc compound.
Oil of Lubricating viscosity/Base Oil Component
The oil of lubricating viscosity for use in the lubricating oil compositions
of this disclosure,
also referred to as a base oil, is typically present in a major amount, e.g.,
an amount of greater
than 50 wt. %, preferably greater than about 70 wt. %, more preferably from
about 80 to about
99.5 wt. % and most preferably from about 85 to about 98 wt. %, based on the
total weight of
the composition. The expression "base oil" as used herein shall be understood
to mean a base
stock or blend of base stocks which is a lubricant component that is produced
by a single
manufacturer to the same specifications (independent of feed source or
manufacturer's
location); that meets the same manufacturer's specification; and that is
identified by a unique
formula, product identification number, or both. The base oil for use herein
can be any presently
known or later-discovered oil of lubricating viscosity used in formulating
lubricating oil
compositions for any and all such applications, e.g., engine oils, marine
cylinder oils, functional
fluids such as hydraulic oils, gear oils, transmission fluids, etc.
Additionally, the base oils for
use herein can optionally contain viscosity index improvers, e.g., polymeric
alkylmethacrylates; olefinic copolymers, e.g., an ethylene-propylene copolymer
or a styrene-
diene copolymer; and the like and mixtures thereof
As one skilled in the art would readily appreciate, the viscosity of the base
oil
is dependent upon the application. Accordingly, the viscosity of a base oil
for use herein will
ordinarily range from about 2 to about 2000 centistokes (cSt) at 100
Centigrade (C.).
Generally, individually the base oils used as engine oils will have a
kinematic viscosity range
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about 16 cSt, and most
preferably about 4 cSt to about 12 cSt and will be selected or blended
depending on the desired
end use and the additives in the finished oil to give the desired grade of
engine oil, e.g., a
lubricating oil composition having an SAE Viscosity Grade of OW, OW-8, OW-12,
OW-16, OW-
20, OW-26, OW-30, OW-40, 0W-50, OW-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60,
10 10W, 10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30, 15W-40, 30, 40
and the
like.
Group I base oils generally refer to a petroleum derived lubricating base oil
having a saturates
content of less than 90 wt. % (as determined by ASTM D 2007) and/or a total
sulfur content of
greater than 300 ppm (as determined by ASTM D 2622, ASTM D 4294, ASTM D 4297
or
.. ASTM D 3120) and has a viscosity index (VI) of greater than or equal to 80
and less than 120
(as determined by ASTM D 2270).
Group II base oils generally refer to a petroleum derived lubricating base oil
having a total
sulfur content equal to or less than 300 parts per million (ppm) (as
determined by ASTM D
2622, ASTM D 4294, ASTM D 4927 or ASTM D 3120), a saturates content equal to
or greater
than 90 weight percent (as determined by ASTM D 2007), and a viscosity index
(VI) of
between 80 and 120 (as determined by ASTM D 2270).
Group III base oils generally refer to a petroleum derived lubricating base
oil having less than
300 ppm sulfur, a saturates content greater than 90 weight percent, and a VI
of 120 or greater.
Group IV base oils are polyalphaolefins (PA0s).
Group V base oils include all other base oils not included in Group I, II,
III, or IV.
The lubricating oil composition can contain minor amounts of other base oil
components. For
example, the lubricating oil composition can contain a minor amount of a base
oil derived from
natural lubricating oils, synthetic lubricating oils or mixtures thereof
Suitable base oil includes
base stocks obtained by isomerization of synthetic wax and slack wax, as well
as hydrocracked
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base stocks produced by hydrocracking (rather than solvent extracting) the
aromatic and polar
components of the crude.
Suitable natural oils include mineral lubricating oils such as, for example,
liquid petroleum
oils, solvent-treated or acid-treated mineral lubricating oils of the
paraffinic, naphthenic or
mixed paraffinic-naphthenic types, oils derived from coal or shale, animal
oils, vegetable oils
(e.g., rapeseed oils, castor oils and lard oil), and the like.
Suitable synthetic lubricating oils include, but are not limited to,
hydrocarbon oils and halo-
substituted hydrocarbon oils such as polymerized and interpolymerized olefins,
e.g.,
polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated
polybutylenes,
poly(1-hexenes), poly(1-octenes), poly(1-decenes), and the like and mixtures
thereof;
alkylbenzenes such as dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-
ethylhexyl)-benzenes, and the like; polyphenyls such as biphenyls, terphenyls,
alkylated
polyphenyls, and the like; alkylated diphenyl ethers and alkylated diphenyl
sulfides and the
derivative, analogs and homologs thereof and the like.
Other synthetic lubricating oils include, but are not limited to, oils made by
polymerizing
olefins of less than 5 carbon atoms such as ethylene, propylene, butylenes,
isobutene, pentene,
and mixtures thereof Methods of preparing such polymer oils are well known to
those skilled
in the art.
Additional synthetic hydrocarbon oils include liquid polymers of alpha olefins
having the
proper viscosity. Especially useful synthetic hydrocarbon oils are the
hydrogenated liquid
oligomers of C6 to C12 alpha olefins such as, for example, 1-decene trimer.
Another class of synthetic lubricating oils include, but are not limited to,
alkylene oxide
polymers, i.e., homopolymers, interpolymers, and derivatives thereof where the
terminal
hydroxyl groups have been modified by, for example, esterification or
etherification. These
oils are exemplified by the oils prepared through polymerization of ethylene
oxide or propylene
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oxide, the alkyl and phenyl ethers of these polyoxyalkylene polymers (e.g.,
methyl poly
propylene glycol ether having an average molecular weight of 1,000, diphenyl
ether of
polyethylene glycol having a molecular weight of 500-1000, diethyl ether of
polypropylene
glycol having a molecular weight of 1,000-1,500, etc.) or mono- and
polycarboxylic esters
thereof such as, for example, the acetic esters, mixed C3-C8 fatty acid
esters, or the C13 oxo acid
diester of tetraethylene glycol.
Yet another class of synthetic lubricating oils include, but are not limited
to, the esters of
dicarboxylic acids e.g., phthalic acid, succinic acid, alkyl succinic acids,
alkenyl succinic acids,
maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic
acid, linoleic acid
dimer, malonic acids, alkyl malonic acids, alkenyl malonic acids, etc., with a
variety of
alcohols, e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl
alcohol, ethylene
glycol, diethylene glycol monoether, propylene glycol, etc. 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, the complex ester formed by
reacting one mole
of sebacic acid with two moles of tetraethylene glycol and two moles of 2-
ethylhexanoic acid
and the like.
Esters useful as synthetic oils also include, but are not limited to, those
made from carboxylic
acids having from about 5 to about 12 carbon atoms with alcohols, e.g.,
methanol, ethanol, etc.,
polyols and polyol ethers such as neopentyl glycol, trimethylol propane,
pentaerythritol,
dipentaerythritol, tripentaerythritol, and the like.
Silicon-based oils such as, for example, polyalkyl-, polyaryl-, polyalkoxy- or
polyaryloxy-
siloxane oils and silicate oils, comprise another useful class of synthetic
lubricating oils.
Specific examples of these include, but are not limited to, tetraethyl
silicate, tetra-isopropyl
silicate, tetra-(2-ethylhexyl) silicate, tetra-
(4-methyl-hexyl)silicate, tetra-(p-tert-
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butylphenyl)silicate, hexyl-(4-methyl-2-pentoxy)disiloxane,
poly(methyl)siloxanes,
poly(methylphenyl)siloxanes, and the like. Still yet other useful synthetic
lubricating oils
include, but are not limited to, liquid esters of phosphorous containing
acids, e.g., tricresyl
phosphate, trioctyl phosphate, diethyl ester of decane phosphionic acid, etc.,
polymeric
tetrahydrofurans and the like.
The lubricating oil may be derived from unrefined, refined and rerefined oils,
either natural,
synthetic or mixtures of two or more of any of these of the type disclosed
hereinabove.
Unrefined oils are those obtained directly from a natural or synthetic source
(e.g., coal, shale,
or tar sands bitumen) without further purification or treatment. Examples of
unrefined oils
include, but are not limited to, a shale oil obtained directly from retorting
operations, a
petroleum oil obtained directly from distillation or an ester oil obtained
directly from an
esterification process, each of which is then used without further treatment.
Refined oils are
similar to the unrefined oils except they have been further treated in one or
more purification
steps to improve one or more properties. These purification techniques are
known to those of
skill in the art and include, for example, solvent extractions, secondary
distillation, acid or base
extraction, filtration, percolation, hydrotreating, dewaxing, etc. Rerefined
oils are obtained by
treating used oils in processes similar to those used to obtain refined oils.
Such rerefined oils
are also known as reclaimed or reprocessed oils and often are additionally
processed by
techniques directed to removal of spent additives and oil breakdown products.
Lubricating oil base stocks derived from the hydroisomerization of wax may
also be used,
either alone or in combination with the aforesaid natural and/or synthetic
base stocks. Such
wax isomerate oil is produced by the hydroisomerization of natural or
synthetic waxes or
mixtures thereof over a hydroisomerization catalyst.
Natural waxes are typically the slack waxes recovered by the solvent dewaxing
of mineral oils;
synthetic waxes are typically the wax produced by the Fischer-Tropsch process.
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Other useful fluids of lubricating viscosity include non-conventional or
unconventional base
stocks that have been processed, preferably catalytically, or synthesized to
provide high
performance lubrication characteristics.
Non Sulfur-Phosphorus Containing Zinc Compound
The lubrication oil compositions herein can contain one or more non-sulfur
phosphorus
.. containing zinc compounds. Non-sulfur phosphorus containing zinc compounds
is taken to
mean that the zinc additive does not contain both phosphorus and sulfur in the
bonding ligands,
but may separately contain phosphorus or sulfur or neither of those atoms.
Those skilled in the
art will recognize suitable additives have been described in Stahl, L; et al.,
"Zinc
Organometallics" in Comprehensive Organometallic Chemistry III; 1st Edition;
Mingos, D. M.
.. P.; Crabtree, R. H.; Meyer, K.; Eds.; Elsevier: Oxford, 2007, pp 311-412,
and is incorporated
herein by reference. The zinc complexes described in this disclosure are
typically prepared by
reacting a di- or tetravalent zinc reactant with a suitable ligand using
methods apparent to a
practitioner of ordinary skill in the art. The zinc complexes described are
represented by their
most simple molecular formulas, but it is understood in the art that
aggregate, multinuclear,
.. and cluster complexes may also exist in chemical equilibrium with the
simplified molecular
formula. The zinc complexes are generally accepted as meaning the product
between a zinc
reactant and a suitable ligand or ligands. Commonly used zinc reactants
include, but are not
limited to zinc oxide, zinc sulfide, zinc sulfate, zinc chloride, zinc
chloride tetrahydrofuran
complex, dichloro(N,N,N',N'-tetramethylehtylenediamine) zinc, zinc bromide,
zinc iodide,
zinc fluoride, zinc methoxide, zinc phosphate, zinc stearate, zinc
acetylacetonate, zinc acetate,
zinc carbonate hydroxide, zinc naphthenate, or similar zinc compounds. Some
zinc reagents
may exist as a hydrated species. Any one of these zinc compounds described
above can be used
as the zinc compound of the present disclosure. Preferred zinc compounds are
zinc oxide or
zinc chloride. The zinc reactants can also be the zinc compound of the present
disclosure as
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5 long as they do not contain both sulfur and phosphorus. The zinc
complexes described herein
are oil-soluble or oil dispersible.
In one embodiment, the zinc compound can be a zinc alkoxide or thiolate
compound. For
example, the zinc alkoxides or thiolates can be of the form Zn(YRA),Lx where Y
is an oxygen
or sulfur atom, RA is a linear, cyclic, or branched, saturated or unsaturated,
aliphatic
10 hydrocarbon moiety having from 1 to about 20 carbon atoms, n is an
integer from 0 to 2, L is
a ligand that saturates the coordination sphere of zinc, and x is an integer
from 0 to 4. In certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups. For example,
15 the zinc alkoxide can be zinc methoxide or the like.
In one embodiment, the zinc compound can be a zinc aryloxide or arylthiolate
compound. For
example, the zinc aryloxide or arylthiolate is of the following Formula 1:
RB
e
RB y ZnLõ
RB (Formula 1)
where RB is a hydrogen atom or a linear, cyclic, or branched, saturated or
unsaturated, aliphatic
hydrocarbon moiety having from 1 to about 30 carbon atoms, Y is an oxygen atom
or sulfur
atom, n is an integer from 0 to 2, L is a ligand that saturates the
coordination sphere of zinc,
and x is an integer from 0 to 4. In certain embodiments, the ligand, L, is
selected from the group
consisting of water, hydroxide, phosphine, phosphite, ammonia, amino, amido,
alkylthiolate,
halide, and combinations thereof so long as the zinc species does not contain
both sulfur and
phosphorus groups.
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In one embodiment, the zinc compound can be a colloidal dispersion of zinc
oxide. For
example, zinc oxide has the net molecular formula of ZnO, but can comprise
repeating [Zn-O-
Znin units. In certain embodiments, the colloidal dispersion of zinc oxide
will comprise an
average nanoparticle size < 100 nm as determined by microscopic techniques
such as TEM. To
assist in the dispersion of the colloidal particles a solvent can be added.
For example, US
20160237373, incorporated herein by reference, teaches that a C1-C3 alcohol
solvent can be
used to disperse zinc oxide nanoparticles in oil. Generally, the amount of the
colloidal
dispersion of zinc oxide can be from about 0.01 wt. % to about 5 wt. %.
In another embodiment, the zinc compound can be a stable colloidal suspension.
For example,
US Pat. No. 7,884,058, incorporated herein by reference, discloses stable
colloidal suspensions
of various inorganic oxides. These can be prepared in the presence of an oil
phase with a
dispersing agent that includes polyalkylene succinic anhydrides, non-nitrogen
containing
derivatives of a polyalkylene succinic anhydride selected from the group
consisting of a
polyalkylene succinic acid, a Group I and/or Group fl mono- or di-salt of a
polyalkylene
succinic acid, a polyalkylene succinate ester formed by the reaction of a
polyalkylene succinic
anhydride or an acid chloride with an alcohol and mixtures thereof, and
mixtures thereof and a
diluent oil, wherein the stable colloidal suspension is substantially clear.
In one embodiment, the zinc compound can be a zinc amido compound. For
example, the zinc
amido compound can be of the form Zn(NRc),Lx where Rc is a trimethylsilyl
group or a linear,
cyclic, or branched, and saturated or unsaturated, aliphatic hydrocarbon
moiety having from 1
to about 20 carbon atoms, n is an integer from 0 to 2, L is a ligand that
saturates the coordination
sphere of zinc, and x is an integer from 0 to 4. In certain embodiments, the
ligand, L, is selected
from the group consisting of water, hydroxide, phosphine, phosphite, ammonia,
amino, amido,
alkylthiolate, halide, and combinations thereof so long as the zinc species
does not contain both
sulfur and phosphorus groups.
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In one embodiment, the zinc compound can be a zinc acetylacetonate compound.
For example,
the zinc acetylacetonate is of the following Formula 2:
0 0 e 1
RD), RD Zn1_,
[
n (Formula 2),
where RD can be a symmetric or asymmetric linear, cyclic, or branched,
saturated or
unsaturated, aliphatic hydrocarbon moiety having from 1 to about 20 carbon
atoms, or an
aromatic moiety, n is an integer from 0 to 2, L is a ligand that saturates the
coordination sphere
of zinc, and xis an integer from 0 to 4. In certain embodiments, the ligand,
L, is selected from
the group consisting of water, hydroxide, phosphine, phosphite, ammonia,
amino, amido,
alkylthiolate, halide, and combinations thereof so long as the zinc species
does not contain both
sulfur and phosphorus groups.
In one embodiment, the zinc compound can be a zinc carboxylate. For example,
the zinc
carboxylate is of the following Formula 3:
[0
REAcp ZnLõ
- n (Formula 3),
where RE can be a linear, cyclic, or branched, saturated or unsaturated,
aliphatic hydrocarbon
moiety having from 1 to about 50 carbon atoms, or aromatic and alkylaromatic
rings with alkyl
groups that can be linear, cyclic, or branched, and saturated or unsaturated,
aliphatic
hydrocarbon moiety having from 1 to about 20 carbon atoms, n is an integer
from 0 to 2, L is a
ligand that saturates the coordination sphere of zinc, and x is an integer
from 0 to 4. In certain
embodiments, the zinc carboxylate can form small clusters of the form
Zn3(02CRE)6Lx. In
certain embodiments, 02CRE can represent a napthenate residue, which is
generally understood
to be complex mixtures of cycloaliphatic residues obtained by oxidation of
naphtha. In certain
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18
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups. For example,
the zinc carboxylate can be zinc stearate or another fatty acid. The zinc
carboxylate can also
be, for example, zinc octoate or zinc 2-ethylhexanoate.
In one embodiment, the zinc compound can be a zinc alkylhydroxybenzoate. For
example, the
zinc salicylate is of the following Formula 4:
1 rsne ZnLõ
R
¨ n (Formula 4),
where RF is a hydrogen atom, a linear, cyclic, or branched, saturated or
unsaturated, aliphatic
hydrocarbon moiety having from 1 to about 30 carbon atoms, p is an integer
from 1 to 2, n is
an integer from 0 to 2, L is a ligand that saturates the coordination sphere
of zinc, and x is an
integer from 0 to 4. Particularly, n is an integer from 0 to 2. In certain
embodiments, the ligand,
L, is selected from the group consisting of water, hydroxide, phosphine,
phosphite, ammonia,
amino, amido, alkylthiolate, halide, and combinations thereof so long as the
zinc species does
not contain both sulfur and phosphorus groups. In one embodiment, the
alkylhydroxybenzoate
is a salicylate. In some embodiments, alkali earth metals such as magnesium,
calcium,
strontium, and barium may be added. Alkali earth metals are typically basic
salts which can
include, but are not limited to, metal oxides, metal alkoxides, metal
carbonates, and metal
bicarbonates.
In another embodiment, the zinc compound can be a zinc arylsulfonate. For
example, the zinc
arylsufonate is of the following Formula 5:
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8 pl
x
03S u Zn L
-"IRq
n (Formula 5),
where RG is a hydrogen atom, a linear, cyclic, or branched, saturated or
unsaturated, aliphatic
hydrocarbon moiety having from 1 to about 30 carbon atoms, p is an integer
from 1 to 5, n is
an integer from 0 to 2, L is a ligand that saturates the coordination sphere
of zinc, and x is an
integer from 0 to 4. Particularly, n is an integer from 0 to 2. Particularly,
p is 1 or 2. In certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups. In some
embodiments, alkali earth metals such as magnesium, calcium, strontium, and
barium may be
added. Alkali earth metals are typically basic salts which can include, but
are not limited to,
metal oxides, metal alkoxides, metal carbonates, and metal bicarbonates.
In one embodiment, the zinc compound can be a zinc sulfurized phenate. For
example, the zinc
sulfurized phenate is of the following Formula 6:
(s)x, ________________________________ ZnLx
_ RH - n (Formula 6),
where RH is a hydrogen atom, a linear, cyclic, or branched, saturated or
unsaturated, aliphatic
hydrocarbon moiety having from 1 to about 30 carbon atoms, x' is an integer
from 1 to zinc 8,
n is an integer from 1 to about 15, L is a ligand that saturates the
coordination sphere of zinc,
and x is an integer from 0 to 4. Particularly, n is an integer from 1 to about
5. In certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
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5 phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups. In some
embodiments, alkali earth metals such as magnesium, calcium, strontium, and
barium may be
added. Alkali earth metals are typically basic salts which can include, but
are not limited to,
metal oxides, metal alkoxides, metal carbonates, and metal bicarbonates.
10 In one embodiment, the zinc compound can be a zinc dithiocarbamato
complex. For example,
the zinc dithiocarbamate is of Formula 7:
es)LN-RI ZnI_õ
RI _ n
(Formula 7),
where each RI is independently a linear, cyclic, or branched, saturated or
unsaturated, aliphatic
hydrocarbon moiety having from 1 to about 10 carbon atoms, n is an integer
from 0 to 2, L is
15 a ligand that saturates the coordination sphere of zinc, and x is an
integer from 0 to 4. In certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
ammonia, amino, amido, alkylthiolate, halide, and combinations thereof
In one embodiment, the zinc compound can be a salen complex. For example, the
zinc salen is
of Formula 8:
Ry) Ry
Y=N N=Y
õ
Rj 411 0 0 Rj ZnI_
Rj R j
20 ¨n (Formula 8),
where each RJ is independently a hydrogen atom, or a linear, cyclic, or
branched, saturated or
unsaturated, hydrocarbon moiety having from 1 to about 8 carbon atoms, each Y
is
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21
independently -C(Itr)z where RJ" is a hydrogen atom, a linear, cyclic, or
branched, saturated
or unsaturated, aliphatic hydrocarbon moiety having from 1 to about 8 carbon
atoms, or an
aromatic ring, z is 1 or 2 when N is imido or amino, respectively, each RJ' is
independently a
hydrogen atom, or a linear, cyclic, or branched, saturated or unsaturated,
aliphatic chains
hydrocarbon moiety having from 1 to about 8 carbon atoms, or taken together
with the atoms
to which they are connected form a 5-, 6-, or 7-membered ring (can be
aromatic, completely
saturated, or contain varying levels of unsaturation), n is an integer from 0
to 2, L is a ligand
that saturates the coordination sphere of zinc, and x is an integer from 0 to
4. In certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups.
In one embodiment, the zinc compound can be a bimetallic zinc complex. For
example, the
bimetallic zinc complex is of Formula 9:
RK"
RK,, Zn Zn/ 1-Ric
Lõ
RK, N 0 N. RK,
RK,/
RK (Formula 9),
where RI( is a hydrogen atom, or a linear, cyclic, or branched, saturated or
unsaturated,
hydrocarbon moiety having from 1 to about 30 carbon atoms, each RK" is
independently a
hydrogen atom, a linear, cyclic, or branched, saturated or unsaturated,
aliphatic hydrocarbon
moiety having from 1 to about 8 carbon atoms, or an aromatic ring, each RI('
is independently
a hydrogen atom, or a linear, cyclic, or branched, saturated or unsaturated,
aliphatic
hydrocarbon moiety having from 1 to about 8 carbon atoms, or taken together
with the atoms
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22
to which they are connected form a 5-, 6-, or 7-membered ring (can be
completely saturated or
contain varying levels of unsaturation), L is a ligand that saturates the
coordination sphere of
the zincs, and x is an integer from 0 to 4. In certain embodiments, the
ligand, L, is selected
from the group consisting of water, hydroxide, phosphine, phosphite, ammonia,
amino, amido,
alkylthiolate, halide, and combinations thereof so long as the zinc species
does not contain both
sulfur and phosphorus groups.
In one embodiment, the zinc compound can be a phosphate ester, phospinate, or
phosphinite
complex. For example, the zinc phosphate esters, phosphite, phospinates, or
phosphinites are
of the following Formulal 0 :
e Zn1_,
RL
n (Formula 10),
where W is an oxo or an unbonded pair of electrons when the phosphorous atom
is in the +5
or +3 oxidation state, respectively, each It. is independently a linear,
cyclic, or branched,
saturated or unsaturated, aliphatic hydrocarbon moiety having from 1 to about
10 carbon atoms,
an aromatic ring or an alkoxide moiety, n is an integer from 0 to 2, L is a
ligand that saturates
the coordination sphere of zinc, and x is an integer from 0 to 4. In some
embodiments, the zinc
phosphate esters, phosphite, phospinates, and phosphinites structures are
dimeric with bridging
ligand groups. In certain embodiments, the ligand, L, is selected from the
group consisting of
water, hydroxide, phosphine, phosphite, ammonia, amino, amido, halide, and
combinations
thereof
In one embodiment, the zinc compound can be pyridyl, polypyridyl, and
quinolinolato
complexes. For example, pyridyl, polypyridyl, and quinolinolato complexes of
zinc are of the
following Formula 11:
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Rm
3' 27
1\11
3 2(Rm _ n
(Formula 11),
where Rm is independently a hydrogen atom or a linear, cyclic, or branched,
saturated or
unsaturated, aliphatic hydrocarbon moiety having from 1 to about 10 carbon
atoms, a pyridyl
ring typically substituted at the 2 position which can be unfuctionalized or
can be connected to
the other functionalized pyridyl rings to make fused ring systems commonly
referred to 8-
hydroxyquinolines, quinolines, or phenanthrolines, n is an integer from 0 to
2, L is a ligand that
saturates the coordination sphere of zinc, and x is an integer from 0 to 4. In
certain
embodiments, the ligand, L, is selected from the group consisting of water,
hydroxide,
phosphine, phosphite, ammonia, amino, amido, alkylthiolate, halide, and
combinations thereof
so long as the zinc species does not contain both sulfur and phosphorus
groups.
In one embodiment, a zinc reactant can be complexed to a basic nitrogen
dispersant
succinimide. The basic nitrogen succinimide used to prepare the zinc complexes
has at least
one basic nitrogen and is preferably oil-soluble. The succinimide compositions
may be post-
treated with, e.g., boron, using procedures well known in the art so long as
the compositions
continue to contain basic nitrogen. The mono and polysuccinimides that can be
used to prepare
the zinc complexes described herein are disclosed in numerous references and
are well known
in the art. Certain fundamental types of succinimides and the related
materials encompassed by
the term of art "succinimide" are taught in U.S. Pat. No's. 3,219,666;
3,172,892; and 3,272,746,
the disclosures of which are hereby incorporated by reference. The term
"succinimide" is
understood in the art to include many of the amide, imide, and amidine species
which may also
be formed. The predominant product however is a succinimide and this term has
been generally
accepted as meaning the product of a reaction of an alkenyl substituted
succinic acid or
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24
anhydride with a nitrogen-containing compound. Preferred succinimides, because
of their
commercial availability, are those succinimides prepared from a hydrocarbyl
succinic
anhydride, wherein the hydrocarbyl group contains from about 24 to about 350
carbon atoms,
and an ethylene amine, said ethylene amines being especially characterized by
ethylene
diamine, diethylene triamine, triethylene tetramine, and tetraethylene
pentamine. Particularly
preferred are those succinimides prepared from polyisobutenyl succinic
anhydride of 70 to 128
carbon atoms and tetraethylene pentamine or triethylene tetramine or mixtures
thereof Also
included within the term "succinimide" are the cooligomers of a hydrocarbyl
succinic acid or
anhydride and a poly secondary amine containing at least one tertiary amino
nitrogen in
addition to two or more secondary amino groups. Ordinarily this composition
has between
1,500 and 50,000 average molecular weight. A typical compound would be that
prepared by
reacting polyisobutenyl succinic anhydride and ethylene dipiperazine.
Succinimides having an average molecular weight of 1000 or 1300 or 2300 and
mixtures
thereof are most preferred.
Generally, the amount of the non-sulfur-phosphorus containing zinc compound
can be from
about 0.001 wt. % to about 25 wt. %, from about 0.05 wt. % to about 20 wt. %,
or from about
0.1 wt. % to about 15 wt. %, or from about 0.5 wt. % to about 5 wt. %, from
about, 1.0 wt. %
to about 4.0 wt. %, based on the total weight of the lubricating oil
composition.
In an aspect, the present disclosure provides a lubricating engine oil
composition for a direct
injected, boosted, spark ignited internal combustion engine comprising at
least one non-sulfur-
phosphorus containing zinc compound. In one embodiment, the amount of metal
from the at
least one non-sulfur-phosphorus containing zinc compound is from about 200 to
about 3000
ppm, or from about 250 to about 3000 ppm, from about 300 to about 3000 ppm,
from about
350 to about 3000 ppm, from about 400 ppm to about 3000 ppm, from about 500 to
about 3000
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5 ppm, from about 600 to about 3000 ppm, from about 700 to about 3000 ppm,
from about 900
to about 3000, from about 950 to about 3000 ppm, from about 1000 to 3000 ppm,
from about
1050 to about 3000 ppm, from about 1100 to about 3000 ppm, from about 1200 to
about 3000
ppm, from about 1300 to about 3000 ppm, from about 1400 to about 3000 ppm, or
from about
1400 to 3000 ppm.
10 In an aspect, the present disclosure provides a lubricating engine oil
composition for a direct
injected, boosted, spark ignited internal combustion engine comprising at
least one non-sulfur-
phosphorus containing zinc compound and a ZnDTP. In one embodiment, the amount
of metal
from the at least one non-sulfur-phosphorus containing zinc compound and ZnDTP
is from
about 700 to about 4000 ppm, or from about 800 to about 4000 ppm, from about
900 to about
15 4000, from about 950 to about 4000 ppm, from about 1000 to 4000 ppm,
from about 1050 to
about 4000 ppm, from about 1100 to about 4000 ppm, from about 1200 to about
4000 ppm,
from about 1300 to about 4000 ppm, from about 1400 to about 4000 ppm, or from
about 1400
to 4000 ppm.
In an aspect, the present disclosure provides a method for improving deposit
control
20 performance while at the same time preventing or reducing low speed pre-
ignition in a direct
injected, boosted, spark ignited internal combustion engine, said method
comprising the step
of lubricating the crankcase of the engine with a lubricating oil composition
comprising at least
one non-sulfur-phosphorus containing zinc compound. In one embodiment, the
zinc
compounds does not contain sulfur or phosphorus. In one embodiment, the zinc
compound is
25 a zinc carboxylate as described herein.
Generally, the amount of the non-sulfur-phosphorus containing zinc compound
can be from
about 0.001 wt. % to about 25 wt. %, from about 0.05 wt. % to about 20 wt. %,
or from about
0.1 wt. % to about 15 wt. %, or from about 0.1 wt. % to about 5 wt. %, from
about, 0.1 wt. %
to about 4.0 wt. %, based on the total weight of the lubricating oil
composition.
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In one embodiment, the non-sulfur-phosphorus containing zinc compound can be
combined
with conventional lubricating oil detergent additives which contain magnesium
and/or calcium.
In one embodiment the calcium detergent(s) can be added in an amount
sufficient to provide
the lubricating oil composition from 0 to about 2400 ppm of calcium metal,
from 0 to about
2200 ppm of calcium metal, from 100 to about 2000 ppm of calcium metal, from
200 to about
1800 ppm of calcium metal, or from about 100 to about 1800 ppm, or from about
200 to about
1500 ppm, or from about 300 to about 1400 ppm, or from about 400 to about 1400
ppm, of
calcium metal in the lubricating oil composition. In one embodiment the
magnesium
detergent(s) can be added in an amount sufficient to provide the lubricating
oil composition
from about 100 to about 1000 ppm of magnesium metal, or from about 100 to
about 600 ppm,
or from about 100 to about 500 ppm, or from about 200 to about 500 ppm of
magnesium metal
in the lubricating oil composition.
In one embodiment, the non-sulfur-phosphorus containing zinc compound can be
combined
with conventional lubricating oil detergent additives which contain lithium.
In one embodiment
the lithium detergent(s) can be added in an amount sufficient to provide the
lubricating oil
composition from 0 to about 2400 ppm of lithium metal, from 0 to about 2200
ppm of lithium
metal, from 100 to about 2000 ppm of lithium metal, from 200 to about 1800 ppm
of lithium
metal, or from about 100 to about 1800 ppm, or from about 200 to about 1500
ppm, or from
about 300 to about 1400 ppm, or from about 400 to about 1400 ppm, of lithium
metal in the
lubricating oil composition.
In one embodiment, the non-sulfur-phosphorus containing zinc compound can be
combined
with conventional lubricating oil detergent additives which contain sodium. In
one embodiment
the sodium detergent(s) can be added in an amount sufficient to provide the
lubricating oil
composition from 0 to about 2400 ppm of sodium metal, from 0 to about 2200 ppm
of sodium
metal, from 100 to about 2000 ppm of sodium metal, from 200 to about 1800 ppm
of sodium
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.. metal, or from about 100 to about 1800 ppm, or from about 200 to about 1500
ppm, or from
about 300 to about 1400 ppm, or from about 400 to about 1400 ppm, of sodium
metal in the
lubricating oil composition.
In one embodiment, the non-sulfur-phosphorus containing zinc compound can be
combined
with conventional lubricating oil detergent additives which contain potassium.
In one
embodiment the potassium detergent(s) can be added in an amount sufficient to
provide the
lubricating oil composition from 0 to about 2400 ppm of potassium metal, from
0 to about 2200
ppm of potassium metal, from 100 to about 2000 ppm of potassium metal, from
200 to about
1800 ppm of potassium metal, or from about 100 to about 1800 ppm, or from
about 200 to
about 1500 ppm, or from about 300 to about 1400 ppm, or from about 400 to
about 1400 ppm,
of potassium metal in the lubricating oil composition.
In one embodiment, the disclosure provides a lubricating engine oil
composition comprising a
lubricating oil base stock as a major component; and at least one non-sulfur-
phosphorus
containing zinc compound, as a minor component; and wherein the engine
exhibits greater than
50% reduced low speed pre-ignition, based on normalized low speed pre-ignition
(LSPI) counts
per 100,000 engine cycles, engine operation at between 500 and 3,000
revolutions per minute
and brake mean effective pressure (BMEP) between 10 and 30 bar, as compared to
low speed
pre-ignition performance achieved in an engine using a lubricating oil that
does not comprise
the at least one non-sulfur-phosphorus containing zinc compound.
In one aspect, the disclosure provides a lubricating engine oil composition
for use in a down-
sized boosted engine comprising a lubricating oil base stock as a major
component; and at least
one non-sulfur-phosphorus containing zinc compound, as a minor component;
where the
downsized engine ranges from about 0.5 to about 3.6 liters, from about 0.5 to
about 3.0 liters,
from about 0.8 to about 3.0 liters, from about 0.5 to about 2.0 liters, or
from about 1.0 to about
2.0 liters. The engine can have two, three, four, five or six cylinders.
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In an aspect, the present disclosure provides the use of a at least one non-
sulfur-phosphorus
containing zinc compound for preventing or reducing low speed pre-ignition in
a direct
injected, boosted, spark ignited internal combustion engine.
Lubricating Oil Additives
In addition to the zinc compound described herein, the lubricating oil
composition can
comprise additional lubricating oil additives.
The lubricating oil compositions of the present disclosure may also contain
other conventional
additives that can impart or improve any desirable property of the lubricating
oil composition
in which these additives are dispersed or dissolved. Any additive known to a
person of ordinary
skill in the art may be used in the lubricating oil compositions disclosed
herein. Some suitable
additives have been described in Mortier et al., "Chemistry and Technology of
Lubricants",
2nd Edition, London, Springer, (1996); and Leslie R. Rudnick, "Lubricant
Additives:
Chemistry and Applications", New York, Marcel Dekker (2003), both of which are
incorporated herein by reference. For example, the lubricating oil
compositions can be blended
with antioxidants, anti-wear agents, metal detergents, rust inhibitors,
dehazing agents,
demulsifying agents, metal deactivating agents, friction modifiers, pour point
depressants,
antifoaming agents, co-solvents, corrosion-inhibitors, ashless dispersants,
multifunctional
agents, dyes, extreme pressure agents and the like and mixtures thereof. A
variety of the
additives are known and commercially available. These additives, or their
analogous
compounds, can be employed for the preparation of the lubricating oil
compositions of the
disclosure by the usual blending procedures.
The lubricating oil composition of the present invention can contain one or
more detergents.
Metal-containing or ash-forming detergents function as both detergents to
reduce or remove
deposits and as acid neutralizers or rust inhibitors, thereby reducing wear
and corrosion and
extending engine life. Detergents generally comprise a polar head with a long
hydrophobic tail.
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The polar head comprises a metal salt of an acidic organic compound. The salts
may contain a
substantially stoichiometric amount of the metal in which case they are
usually described as
normal or neutral salts. A large amount of a metal base may be incorporated by
reacting excess
metal compound (e.g., an oxide or hydroxide) with an acidic gas (e.g., carbon
dioxide).
Detergents that may be used include oil-soluble neutral and overbased
sulforiates, phenates,
sulfitrized phenates, thiophosphonates, salicylates, and naphtlienates and
other oil-soluble
carboxylates of a metal, particularly the alkali or alkaline earth metals,
e.g., barium, sodium,
potassium, lithium, calcium, and magnesium. The most commonly used metals are
calcium
and magnesium, which may both be present in detergents used in a lubricant,
and mixtures of
calcium and/or magnesium with sodium.
.. The lubricating oil composition of the present invention can contain one or
more anti-wear
agents that can reduce friction and excessive wear. Any anti-wear agent known
by a person of
ordinary skill in the art may be used in the lubricating oil composition. Non-
limiting examples
of suitable anti-wear agents include zinc dithiophosphate, metal (e.g., Pb,
Sb, Mo and the like)
salts of dithiophosphates, metal (e.g., Zn, Pb, Sb, Mo and the like) salts of
dithiocarbamates,
metal (e.g., Zn, Pb, Sb and the like) salts of fatty acids, boron compounds,
phosphate esters,
phosphite esters, amine salts of phosphoric acid esters or thiophosphoric acid
esters, reaction
products of dicyclopentadiene and thiophosphoric acids and combinations
thereof The amount
of the anti-wear agent may vary from about 0.01 wt. % to about 5 wt. %, from
about 0.05 wt.
% to about 3 wt. %, or from about 0.1 wt. % to about 1 wt. %, based on the
total weight of the
lubricating oil composition.
In certain embodiments, the anti-wear agent is or comprises a dihydrocarbyl
dithiophosphate
metal salt, such as zinc dialkyl dithiophosphate compounds. The metal of the
dihydrocarbyl
dithiophosphate metal salt may be an alkali or alkaline earth metal, or
aluminum, lead, tin,
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5 .. molybdenum, manganese, nickel or copper. In some embodiments, the metal
is zinc. In other
embodiments, the alkyl group of the dihydrocarbyl dithiophosphate metal salt
has from about
3 to about 22 carbon atoms, from about 3 to about 18 carbon atoms, from about
3 to about 12
carbon atoms, or from about 3 to about 8 carbon atoms. In further embodiments,
the alkyl group
is linear or branched.
10 The amount of the dihydrocarbyl dithiophosphate metal salt including the
zinc dialkyl
dithiophosphate salts in the lubricating oil composition disclosed herein is
measured by its
phosphorus content. In some embodiments, the phosphorus content of the
lubricating oil
composition disclosed herein is from about 0.01 wt. % to about 0.14 wt. %,
based on the total
weight of the lubricating oil composition.
15 The lubricating oil composition of the present invention can contain one
or more friction
modifiers that can lower the friction between moving parts. Any friction
modifier known by a
person of ordinary skill in the art may be used in the lubricating oil
composition. Non-limiting
examples of suitable friction modifiers include fatty carboxylic acids;
derivatives (e.g., alcohol,
esters, borated esters, amides, metal salts and the like) of fatty carboxylic
acid; mono-, di- or
20 tri-alkyl substituted phosphoric acids or phosphonic acids; derivatives
(e.g., esters, amides,
metal salts and the like) of mono-, di- or tri-alkyl substituted phosphoric
acids or phosphonic
acids; mono-, di- or tri-alkyl substituted amines; mono- or di-alkyl
substituted amides and
combinations thereof In some embodiments examples of friction modifiers
include, but are
not limited to, alkoxylated fatty amines; borated fatty epoxides; fatty
phosphites, fatty
25 epoxides, fatty amines, borated alkoxylated fatty amines, metal salts of
fatty acids, fatty acid
amides, glycerol esters, borated glycerol esters; and fatty imidazolines as
disclosed in U.S.
Patent No. 6,372,696, the contents of which are incorporated by reference
herein; friction
modifiers obtained from a reaction product of a C4 to C75, or a C6 to C24, or
a C6 to C20, fatty
acid ester and a nitrogen-containing compound selected from the group
consisting of ammonia,
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and an alkanolamine and the like and mixtures thereof. The amount of the
friction modifier
may vary from about 0.01 wt. % to about 10 wt. %, from about 0.05 wt. % to
about 5 wt. %,
or from about 0.1 wt. % to about 3 wt. %, based on the total weight of the
lubricating oil
composition.
The lubricating oil composition of the disclosure can contain a molybdenum-
containing
friction modifier. The molybdenum-containing friction modifier can be any one
of the known
molybdenum-containing friction modifiers or the known molybdenum-containing
friction
modifier compositions.
Preferred molybdenum-containing friction modifier is, for example, sulfurized
oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum dithiophosphate, amine-
molybdenum complex compound, oxymolybdenum diethylate amide, and oxymolybdenum
monoglyceride. Most preferred is a molybdenum dithiocarbamate friction
modifier.
The lubricating oil composition of the invention generally contains the
molybdenum-
containing friction modifier in an amount of 0.01 to 0.15 wt. % in terms of
the molybdenum
content.
The lubricating oil composition of the invention preferably contains an
organic oxidation
inhibitor in an amount of 0.01-5 wt. %, preferably 0.1-3 wt. %. The oxidation
inhibitor can be
a hindered phenol oxidation inhibitor or a diarylamine oxidation inhibitor.
The diarylamine
oxidation inhibitor is advantageous in giving a base number originating from
the nitrogen
atoms. The hindered phenol oxidation inhibitor is advantageous in producing no
NOx gas.
Examples of the hindered phenol oxidation inhibitors include 2,6-di-t-butyl-p-
cresol, 4,4'-
methylenebis(2,6-di-t-butylphenol), 4,4 '-methyleneb is (6-t-butyl-o-cre
sol), 4,4'-
isopropylidenebis(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 2,2'-
methylenebis(4-
methy1-6-t-butylphenol), 4,4'-thiobis(2-methyl-6-t-butylphenol), 2,2-thio-
diethylenebis [3-
(3,5 -di-t-butyl-4 -hydroxyphenyl)propionatel , octyl
3 -(3,5 -di-t-buty1-4-
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hydroxyphenyl)propionate, octadecyl 3-(3,5-di-t-buty1-4-
hydroxyphenyl)propionate, and octyl
3-(3,54-buty1-4-hydroxy-3-methylphenyl)propionate, and commercial products
such as, but
not limited to, Irganox L135 (BASF), Naugalube 531 (Chemtura), and Ethanox
376 (SI
Group).
Examples of the diarylamine oxidation inhibitors include alkyldiphenylamine
having a mixture
of alkyl groups of 4 to 9 carbon atoms, p,p'-dioctyldiphenylamine, phenyl-
naphthylamine,
phenyl-naphthylamine, alkylated-naphthylamine, and alkylated phenyl-
naphthylamine.
Each of the hindered phenol oxidation inhibitor and diarylamine oxidation
inhibitor can be
employed alone or in combination. If desired, other oil soluble oxidation
inhibitors can be
employed in combination with the above-mentioned oxidation inhibitor(s).
The lubricating oil composition of the invention may further contain an
oxymolybdenum
complex of succinimide, particularly a sulfur-containing oxymolybdenum complex
of
succinimide. The sulfur-containing oxymolybdenum complex of succinimide can
provide
increased oxidation inhibition when it is employed in combination with the
above-mentioned
phenolic or amine oxidation inhibitors.
In the preparation of lubricating oil formulations, it is common practice to
introduce the
additives in the form of 10 to 80 wt. % active ingredient concentrates in
hydrocarbon oil, e.g.
mineral lubricating oil, or other suitable solvent.
Usually these concentrates may be diluted with 3 to 100, e.g., 5 to 40, parts
by weight of
lubricating oil per part by weight of the additive package in forming finished
lubricants, e.g.
crankcase motor oils. The purpose of concentrates, of course, is to make the
handling of the
various materials less difficult and awkward as well as to facilitate solution
or dispersion in the
final blend.
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Processes of Preparing Lubricating Oil Compositions
The lubricating oil compositions disclosed herein can be prepared by any
method known to a
person of ordinary skill in the art for making lubricating oils. In some
embodiments, the base
oil can be blended or mixed with the non-sulfur-phosphorus containing zinc
compound
described herein. Optionally, one or more other additives in additional to the
non-sulfur-
.. phosphorus containing zinc compound can be added. The non-sulfur-phosphorus
containing
zinc compound and the optional additives may be added to the base oil
individually or
simultaneously. In some embodiments, the non-sulfur-phosphorus containing zinc
compound
and the optional additives are added to the base oil individually in one or
more additions and
the additions may be in any order. In other embodiments, the non-sulfur-
phosphorus
containing zinc compound and the additives are added to the base oil
simultaneously,
optionally in the form of an additive concentrate. In some embodiments, the
solubilizing of
the non-sulfur-phosphorus containing zinc compound or any solid additives in
the base oil may
be assisted by heating the mixture to a temperature from about 25 C to about
200 C, from
about 50 C to about 150 C or from about 75 C to about 125 C.
Any mixing or dispersing equipment known to a person of ordinary skill in the
art may be used
for blending, mixing or solubilizing the ingredients. The blending, mixing or
solubilizing may
be carried out with a blender, an agitator, a disperser, a mixer (e.g.,
planetary mixers and double
planetary mixers), a homogenizer (e.g., Gaulin homogenizers and Rannie
homogenizers), a
mill (e.g., colloid mill, ball mill and sand mill) or any other mixing or
dispersing equipment
known in the art.
Application of the Lubricating Oil Compositions
The lubricating oil composition disclosed herein may be suitable for use as
motor oils (that is,
engine oils or crankcase oils), in a spark-ignited internal combustion engine,
particularly a
direct injected, boosted, engine that is susceptible to low speed pre-
ignition.
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The following examples are presented to exemplify embodiments of the invention
but are not
intended to limit the invention to the specific embodiments set forth. Unless
indicated to the
contrary, all parts and percentages are by weight. All numerical values are
approximate. When
numerical ranges are given, it should be understood that embodiments outside
the stated ranges
may still fall within the scope of the invention. Specific details described
in each example
should not be construed as necessary features of the invention.
EXAMPLES
The following examples are intended for illustrative purposes only and do not
limit in any
way the scope of the present invention.
Baseline Formulation
The base line formulation contained a Group 3 base oil, mixture of primary and
secondary dialkyl zinc dithiophosphates in an amount to provide 770 ppm
phosphorus and 890
ppm Zn to the lubricating oil composition, mixture of polyisobutenyl
succinimide dispersants
(borated and ethylene carbonate post-treated), a molybdenum succinimide
complex in an
amount to provide 180 ppm molybdenum to the lubricating oil composition,
alkylated
diphenylamine antioxidant, a borated friction modifier, foam inhibitor, a pour
point depressant,
and an olefin copolymer viscosity index improver.
The lubricating oil compositions were blended into a 5W-30 viscosity grade
oil.
Zinc compound A
The zinc compound A was prepared a from a C14-C18 alkylphenol with CO2 and ZnO
to form
a low overbased Zn Salicylate (3.8% Zn) with a TBN of 66 based on the additive
concentrate
(35% diluent oil).
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5 Zinc compound B
The zinc compound B is a Zinc dithiocarbamate (i.e.,
(bis((dibutylcarbamothioyl)thio) zinc))
(13.79% Zn).
Zinc compound C
The zinc compound C is a Zinc 2-ethylhexanoate (17.86% Zn).
10 Example 1
A lubricating oil composition was prepared by adding 1809 ppm of the zinc
compound A and
2177 ppm of calcium from a combination of overbased Ca sulfonate and phenate
detergents
to the baseline formulation.
Example 2
15 A lubricating oil composition was prepared by adding 1798 ppm of the
zinc compound B and
2320 ppm of calcium from a combination of overbased Ca sulfonate and phenate
detergents
to the baseline formulation.
Example 3
A lubricating oil composition was prepared by adding 1616 ppm of the zinc
compound C and
20 2177 ppm of calcium from a combination of overbased Ca sulfonate and
phenate detergents
to the baseline formulation.
Example 4
A lubricating oil composition was prepared by adding 774 ppm of the zinc
compound C and
1860 ppm of calcium from a combination of overbased Ca sulfonate and phenate
detergents
25 to the baseline formulation.
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Example 5
A lubricating oil composition was prepared by adding 1626 ppm of the zinc
compound C and
1935 ppm of calcium from a combination of overbased Ca sulfonate and phenate
detergents
to the baseline formulation.
Example 6
A lubricating oil composition was prepared by adding 2488 ppm of the zinc
compound C and
2150 ppm of calcium from a combination of overbased Ca sulfonate and phenate
detergents
to the baseline formulation.
Comparative Example 1
A lubricating oil composition was prepared by adding 2148 ppm of calcium from
a
combination of overbased Ca sulfonate phenate detergents to the baseline
formulation.
Comparative Example 2
A lubricating oil composition was prepared by adding 1858 ppm of calcium from
a
combination of overbased Ca sulfonate phenate detergents to the baseline
formulation.
LSPI Testing
Low Speed Pre-ignition events were measured in a Ford 2.0L Ecoboost engine.
This engine is
a turbocharged gasoline direct injection (GDI) engines.
The Ford LSPI test is operated in four-4 hours iterations. The engine is
operated at 1750 rpm
and 1.7 MPa break mean effective pressure (BMEP) with an oil sump temperature
of 95 C.
The engine is run for 175,000 combustion cycles in each stage.
LSPI events are determined by monitoring peak cylinder pressure (PP) and mass
fraction burn
(MFB) of the fuel charge in the cylinder. When either or both criteria are
met, it can be said
that an LSPI event has occurred. The threshold for peak cylinder pressure
varies by test, but is
typically 4-5 standard deviations above the average cylinder pressure.
Likewise, the MFB
threshold is typically 4-5 standard deviations earlier than the average MFB
(represented in
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crank angle degrees). LSPI events can be reported as average events per test,
events per
100,000 combustion cycles, events per cycle, and/or combustion cycles per
event. The results
for this test is shown below.
Table 1. Ford LSPI Test Results
Ex. 1 Ex. 2 Ex. 3 Ex. 6 Comp. Ex. 1
2688 2506 3378 932 from
ZnDTP
2699 (1798 from Zn (1616 from (2488 from Zn
DTC, Zn 2- 2-
(1809 from ethylhexan ethylhexanoate,
Zn Salicylate, 890 from oate,
ZnDTP) 890 from
890 from 890 from ZnDTP)
Zn (ppm) ZnDTP) ZnDTP)
Ca (ppm) 2177 2320 2177 2150 2148
Average 5 4.75 9 19.25
Cycles* 3.5
Average 2.5 2.5 5.5 12
Cycles* > 90
bar 1.75
1 'Average 2.5 2.25 5.25 11
Cycles* >
100 bar 1.5
Average 2.25 2 4.5 9.5
Cycles* >
110 bar 1.25
Average 1.5 2 3.5 8.5
Cycles* >
120 bar 1
Ex. 4 Ex. 5 Comp. Ex. 2
1664 2516 888 from
ZnDTP
(774 from Zn 2- (1626 from
ethylhexanoate, Zn 2-
ethylhexan
890 from oate,
ZnDTP)
890 from
Zn (ppm) ZnDTP)
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Ca (ppm) 1860 1937 1858
Average 6.75 5.5 9.25
Cycles*
Average 5.25 2 4.5
Cycles* > 90
bar
Average 4.25 1.75 4.25
Cycles* >
100 bar
Average 4.25 1.5 3.75
Cycles* >
110 bar
Average 3.25 1 3.5
Cycles* >
120 bar
*Counts all cycles of LSPI where both MFBO2 and Peak Pressure Requirements are
met
Additionally, a GM 2.0 L LHU 4-cylinder gasoline turbocharged direct-injected
engine was
used for LSPI testing. Each cylinder was equipped with a combustion pressure
sensor.
The data shows that Applicant's inventive example comprising a non-sulfur-
phosphorus zinc
compound provided significantly better LSPI performance both in terms of
number of events
but also the severity of LSPI events than the baseline example which did not
contain the non-
sulfur-phosphorus containing zinc compound in the Ford engines.
