Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LUBRICATING OIL COMPOSITIONS
Inventors: Kevin J. Chase and Shelby A. Skelton and George D. Huron
FIELD OF THE DISCLOSURE
[0001] The present disclosure relates to lubricating oil compositions that
provide enhanced
protection against fatigue.
BACKGROUND
[0002] Modern lubricating oil formulations are formulated to exacting
specifications often set
by original equipment manufacturers. To meet such specifications, various
additives are used,
together with base oil of lubricating viscosity. Depending on the application,
a typical
lubricating oil composition may contain dispersants, detergents, antioxidants,
wear inhibitors,
rust inhibitors, corrosion inhibitors, foam inhibitors, and friction modifiers
just to name a few.
[0003] Different applications will govern the type of additives that will go
into a lubricating
oil composition. For example, lubricants for conventional on-road automobiles
are often
required to meet certain anti-wear specifications but typically do not have
similar requirements
for anti-fatigue performance. However, other lubricating oil compositions may
benefit from
enhanced anti-fatigue properties. These include, for example, functional
fluids and electric
vehicle (EV) fluids which are used in strenuous load bearing environments. In
such
environments, metal surfaces are particularly susceptible to pitting or
formation of cavities
which is caused by repeated loading and contact stresses exceeding surface
fatigue strength of
the material.
[0004] A functional fluid is a term which encompasses a variety of fluids
including but not
limited to tractor hydraulic fluids, power transmission fluids including
automatic transmission
fluids (ATF), traction fluids, continuously variable transmission (CVT) fluids
and manual
transmission fluids, hydraulic fluids, including tractor hydraulic fluids,
gear oils, power
steering fluids, fluids used in wind turbines and fluids related to power
train components. It
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should be noted that within each of these fluids such as, for example,
automatic transmission
fluids, there are a variety of different types of fluids due to the various
transmissions having
different designs which have led to the need for fluids of markedly different
functional
characteristics.
[0005] With respect to tractor hydraulic fluids, these fluids are all-purpose
products used for
all lubricant applications in a tractor except for lubricating the engine. So-
called Super Tractor
Oil Universal fluids or "STOU" fluids also lubricate the engine. These
lubricating applications
may include lubrication of gearboxes, power take-off and clutch(es), rear
axles, reduction
gears, wet brakes, and hydraulic accessories. The components included within a
tractor fluid
must be carefully chosen so that the final resulting fluid composition will
provide all the
necessary characteristics required in the different applications. Such
characteristics may
include the ability to provide proper frictional properties for preventing wet
brake chatter of oil
immersed brakes while simultaneously providing the ability to actuate wet
brakes and provide
power take-off (PTO) clutch performance. A tractor fluid must provide
sufficient anti-wear,
anti-fatigue, and extreme pressure properties as well as water
tolerance/filterability capabilities.
As an example, existing approaches to tractor fluid formulating generally
employ high levels
of sulfur-containing phenates to provide adequate antifatigue properties to
the fluid.
[0006] It is now recognized that what is needed are lubricating oil
compositions with reduced
levels of sulfur-containing phenates. It would also be desirable if such
compositions could be
used in functional fluids (e.g., construction machinery), electric vehicles,
hybrid vehicles
(including plug-in hybrids), and the like, while maintaining acceptable limits
of fatigue
protection of bearings and/or passing severe fatigue specification
requirements.
Advantageously, the compositions described in the present application meet one
or more of the
aforementioned needs and more.
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SUMMARY OF THE INVENTION
[0007] In particular, the present application relates to a lubricant additive
("anti-fatigue
additive") composition that is characterized by enhanced anti-fatigue
properties. In some
embodiments, the anti-fatigue additive imparts enhanced anti-fatigue
properties to a lubricating
oil composition such as those described herein. In some embodiments, the
lubricating oil
composition includes relatively low levels of sulfur-containing compounds that
are typically
used to provide anti-fatigue properties. These sulfur-containing compounds
include sulfurized
high overbased phenates and zinc dithiophosphates.
[0008] More specifically, the application relates to lubricating oil
compositions comprising
0.001% to 1.5% of an anti-fatigue additive and sulfonate detergent. In some
embodiments,
the lubricating oil composition comprises low levels of metal sulfur
containing phenates (e.g.,
about 40 mmol or less of metal from the metal sulfurized phenates, such as 35
mmol or less,
30 mmol or less, 25 mmol or less, 20 mmol or less, 10 mmol or less, and 0
mmol) to provide
improved fatigue protection and performance. The lubricating oil compositions
exhibit
improved fatigue performance even with low levels of sulfur containing
additives by the
addition of glycerol. The compositions described herein often lead to a
reduction in material
fatigue. The compositions also may achieve a reduction in the formation
surface fatigue,
micro-pitting or sub-surface fatigue, and/or pitting of bearings.
[0009] In one embodiment, the application pertains to a functional fluid or EV
fluid comprising
(a) a major amount of an oil of lubricating viscosity; (b) anti-fatigue
additive comprising alkyl
polyol comprising 2 to 20 carbon atoms or derivative thereof and (c) at least
one high overbased
sulfonate detergent and at least one non-sulfonate detergent. In another
embodiment, the
amount of anti-fatigue additive is from about 0.001 wt. % to about 1.5 wt. %
based on the total
weight of the functional fluid or EV fluid. In another embodiment, the anti-
fatigue additive is
added in an amount that increases the fatigue time of the functional fluid or
EV fluid over a
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comparable fluid without anti-fatigue additive thereof as determined by the ZF
bearing pitting
test. In another embodiment, the functional or EV fluids may be employed in
methods of
increasing the fatigue time of a bearing comprising contacting a metal surface
with a functional
fluid or EV fluid.
[0010] In an embodiment, the application pertains to hybrid vehicle fluid or
plug-in hybrid
vehicle fluid comprising (a) a major amount of an oil of lubricating
viscosity; (b) anti-fatigue
additive comprising alkyl polyol comprising 2 to 20 carbon atoms or derivative
thereof and (c)
at least one high overbased sulfonate detergent and at least one non-sulfonate
detergent. In
another embodiment, the amount of anti-fatigue additive is from about 0.001
wt. % to about
1.5 wt. % based on the total weight of the hybrid vehicle fluid or plug-in
hybrid vehicle fluid.
In another embodiment, the anti-fatigue additive is added in an amount that
increases the
fatigue time of the hybrid vehicle fluid or plug-in hybrid vehicle fluid over
a comparable fluid
without anti-fatigue additive thereof as determined by the ZF bearing pitting
test. In another
embodiment, the hybrid vehicle fluid or plug-in hybrid fluid may be employed
in methods of
increasing the fatigue time of a bearing comprising contacting a metal surface
with a hybrid
vehicle fluid or plug-in hybrid vehicle fluid.
DETAILED DESCRIPTION
Definitions
[0011] The following terms will be used throughout the specification and will
have the
following meanings unless otherwise indicated.
[0012] The term "a major amount" of a base oil refers to where the amount of
the base oil is at
least 40 wt. % of the lubricating oil composition. In some embodiments, "a
major amount" of
a base oil refers to an amount of the base oil more than 50 wt. %, more than
60 wt. %, more
than 70 wt. %, more than 80 wt. %, or more than 90 wt. % of the lubricating
oil composition.
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[0013] In the following description, all numbers disclosed herein are
approximate values,
regardless of whether the word "about" or "approximate" is used in connection
therewith. They
may vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10 to 20 percent.
[0014] The term "construction machines" refers to off-road heavy-duty vehicles
and off-road
vehicles and/or machinery including but not limited to excavators, dozers,
loaders, chip
spreaders, pavers, compactors, and cranes.
[0015] "HOB" refers to high overbased with a TBN above 250 on an actives basis
and "LOB"
refers to low overbased with a TBN below 100 on an actives basis.
[0016] "TPP" refers to tetrapropenyl phenol or a salt thereof
[0017] The term "Total Base Number" or "TBN" refers to the level of alkalinity
in an oil
sample, which indicates the ability of the composition to continue to
neutralize corrosive acids,
in accordance with ASTM Standard No. D2896 or equivalent procedure. The test
measures
the change in electrical conductivity, and the results are expressed as
mgKOH/g (the equivalent
number of milligrams of KOH needed to neutralize 1 gram of a product).
Therefore, a high
TBN reflects strongly overbased products and, as a result, a higher base
reserve for neutralizing
acids.
[0018] As used herein, an EV fluid refers to an electric drive fluid used in
electric vehicles
equipped with wet EV motors. Electric drive fluids are analogous to
transmission fluids (used
in conventional vehicles) but with, usually, one or more added functionalities
(e.g., acting as a
coolant for the EV motor, providing electrical resistivity, etc.). The one or
more added
functionalities can provide unique challenges to formulating EV fluids.
[0019] In some embodiments, the lubricating oil composition of the present
invention may
provide anti-fatigue benefits for hybrid vehicles (hybrid vehicle fluids) or
plug-in hybrid
vehicles (plug-in hybrid vehicle fluids) which are equipped with electric
motors.
The Oil of Lubricating Viscosity
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[0020] The lubricating oil compositions disclosed herein generally comprise at
least one oil of
lubricating viscosity. Any base oil known to a skilled artisan can be used as
the oil of
lubricating viscosity disclosed herein. Some base oils suitable for preparing
the lubricating oil
compositions have been described in Mortier et al., "Chemistry and Technology
of Lubricants,"
2nd Edition, London, Springer, Chapters 1 and 2 (1996); and A. Sequeria, Jr.,
"Lubricant Base
Oil and Wax Processing," New York, Marcel Decker, Chapter 6, (1994); and D. V.
Brock,
Lubrication Engineering, Vol. 43, pages 184-5, (1987), all of which are
incorporated herein by
reference. Generally, the amount of the base oil in the lubricating oil
composition may be from
about 70 to about 99.5 wt. %, based on the total weight of the lubricating oil
composition. In
some embodiments, the amount of the base oil in the lubricating oil
composition is from about
75 to about 99 wt. %, from about 80 to about 98.5 wt. %, or from about 80 to
about 98 wt. %,
based on the total weight of the lubricating oil composition.
[0021] In certain embodiments, the base oil is or comprises any natural or
synthetic lubricating
base oil fraction. Some non-limiting examples of synthetic oils include oils,
such as
polyalphaolefins or PA0s, prepared from the polymerization of at least one
alpha-olefin, such
as ethylene, or from hydrocarbon synthesis procedures using carbon monoxide
and hydrogen
gases, such as the Fisher-Tropsch process. In certain embodiments, the base
oil comprises less
than about 10 wt. % of one or more heavy fractions, based on the total weight
of the base oil.
A heavy fraction refers to a lube oil fraction having a viscosity of at least
about 20 cSt at 100
C. In certain embodiments, the heavy fraction has a viscosity of at least
about 25 cSt or at least
about 30 cSt at 100 C. In further embodiments, the amount of the one or more
heavy fractions
in the base oil is less than about 10 wt. %, less than about 5 wt. %, less
than about 2.5 wt. %,
less than about 1 wt. %, or less than about 0.1 wt. %, based on the total
weight of the base oil.
In still further embodiments, the base oil comprises no heavy fraction.
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[0022] In certain embodiments, the lubricating oil compositions comprise a
major amount of a
base oil of lubricating viscosity. In some embodiments, the base oil has a
kinematic viscosity
at 100 C. from about 2.5 centistokes (cSt) to about 20 cSt, from about 4
centistokes (cSt) to
about 20 cSt, or from about 5 cSt to about 16 cSt. The kinematic viscosity of
the base oils or
the lubricating oil compositions disclosed herein can be measured according to
ASTM D 445,
which is incorporated herein by reference.
[0023] In other embodiments, the base oil is or comprises a base stock or
blend of base stocks.
In further embodiments, the base stocks are manufactured using a variety of
different processes
including, but not limited to, distillation, solvent refining, hydrogen
processing,
oligomerization, esterification, and rerefining. In some embodiments, the base
stocks comprise
a rerefined stock. In further embodiments, the rerefined stock shall be
substantially free from
materials introduced through manufacturing, contamination, or previous use.
[0024] In some embodiments, the base oil comprises one or more of the base
stocks in one or
more of Groups I-V as specified in the American Petroleum Institute (API)
Publication 1509,
Fourteen Edition, December 1996 (i.e., API Base Oil Interchangeability
Guidelines for
Passenger Car Motor Oils and Diesel Engine Oils), which is incorporated herein
by reference.
The API guideline defines a base stock as a lubricant component that may be
manufactured
using a variety of different processes. Groups I, II and III base stocks are
mineral oils, each
with specific ranges of the amount of saturates, sulfur content and viscosity
index. Group IV
base stocks are polyalphaolefins (PAO). Group V base stocks include all other
base stocks not
included in Group I, II, III, or W.
[0025] In some embodiments, the base oil comprises one or more of the base
stocks in Group
I, II, III, IV, V or a combination thereof. In other embodiments, the base oil
comprises one or
more of the base stocks in Group II, III, IV or a combination thereof In
further embodiments,
the base oil comprises one or more of the base stocks in Group II, III, IV or
a combination
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thereof wherein the base oil has a kinematic viscosity from about 2.5
centistokes (cSt) to about
20 cSt, from about 4 cSt to about 20 cSt, or from about 5 cSt to about 16 cSt
at 100 C.
[0026] The base oil may be selected from the group consisting of natural oils
of lubricating
viscosity, synthetic oils of lubricating viscosity and mixtures thereof In
some embodiments,
the base oil includes base stocks obtained by isomerization of synthetic wax
and slack wax, as
well as hydrocrackate base stocks produced by hydrocracking (rather than
solvent extracting)
the aromatic and polar components of the crude. In other embodiments, the base
oil of
lubricating viscosity includes natural oils, such as animal oils, vegetable
oils, mineral oils (e.g.,
liquid petroleum oils and solvent treated or acid-treated mineral oils of the
paraffinic,
naphthenic or mixed paraffinic-naphthenic types), oils derived from coal or
shale, and
combinations thereof Some non-limiting examples of animal oils include bone
oil, lanolin,
fish oil, lard oil, dolphin oil, seal oil, shark oil, tallow oil, and whale
oil. Some non-limiting
examples of vegetable oils include castor oil, olive oil, peanut oil, rapeseed
oil, corn oil, sesame
oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, hemp oil,
linseed oil, tung oil,
oiticica oil, jojoba oil, and meadow foam oil. Such oils may be partially or
fully hydrogenated.
[0027] In some embodiments, the synthetic oils of lubricating viscosity
include hydrocarbon
oils and halo-substituted hydrocarbon oils such as polymerized and inter-
polymerized olefins,
alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl
sulfides, as well as
their derivatives, analogues and homologues thereof, and the like. In other
embodiments, the
synthetic oils include alkylene oxide polymers, interpolymers, copolymers and
derivatives
thereof wherein the terminal hydroxyl groups can be modified by
esterification, etherification,
and the like. In further embodiments, the synthetic oils include the esters of
dicarboxylic acids
with a variety of alcohols. In certain embodiments, the synthetic oils include
esters made from
Cs to C12 monocarboxylic acids and polyols and polyol ethers. In further
embodiments, the
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synthetic oils include tri-alkyl phosphate ester oils, such as tri-n-butyl
phosphate and tri-iso-
butyl phosphate.
[0028] In some embodiments, the synthetic oils of lubricating viscosity
include silicon-based
oils (such as the polyakyl-, polyaryl-, polyalkoxy-, polyaryloxy-siloxane oils
and silicate oils).
In other embodiments, the synthetic oils include liquid esters of phosphorus-
containing acids,
polymeric tetrahydrofurans, polyalphaolefins, and the like.
[0029] Base oil derived from the hydroisomerization of wax may also be used,
either alone or
in combination with the aforesaid natural and/or synthetic base oil. Such wax
isomerate oil is
produced by the hydroisomerization of natural or synthetic waxes or mixtures
thereof over a
hydroisomerization catalyst.
[0030] In further embodiments, the base oil comprises a poly-alpha-olefin
(PAO). In general,
the poly-alpha-olefins may be derived from an alpha-olefin having from about 2
to about 30,
from about 4 to about 20, or from about 6 to about 16 carbon atoms. Non-
limiting examples
of suitable poly-alpha-olefins include those derived from octene, decene,
mixtures thereof, and
the like. These poly-alpha-olefins may have a viscosity from about 2 to about
15, from about
3 to about 12, or from about 4 to about 8 centistokes at 100 C. In some
instances, the poly-
alpha-olefins may be used together with other base oils such as mineral oils.
[0031] In further embodiments, the base oil comprises a polyalkylene glycol or
a polyalkylene
glycol derivative, where the terminal hydroxyl groups of the polyalkylene
glycol may be
modified by esterification, etherification, acetylation and the like. Non-
limiting examples of
suitable polyalkylene glycols include polyethylene glycol, polypropylene
glycol,
polyisopropylene glycol, and combinations thereof Non-limiting examples of
suitable
polyalkylene glycol derivatives include ethers of polyalkylene glycols (e.g.,
methyl ether of
polyisopropylene glycol, diphenyl ether of polyethylene glycol, diethyl ether
of polypropylene
glycol, etc.), mono- and polycarboxylic esters of polyalkylene glycols, and
combinations
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thereof In some instances, the polyalkylene glycol or polyalkylene glycol
derivative may be
used together with other base oils such as poly-alpha-olefins and mineral
oils.
[0032] In further embodiments, the base oil comprises any of 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
acid, alkyl malonic acids, alkenyl malonic acids, and the like) with a variety
of alcohols (e.g.,
butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene
glycol, diethylene
glycol monoether, propylene glycol, and the like). Non-limiting 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 like.
[0033] In further embodiments, the base oil comprises a hydrocarbon prepared
by the Fischer-
Tropsch process. The Fischer-Tropsch process prepares hydrocarbons from gases
containing
hydrogen and carbon monoxide using a Fischer-Tropsch catalyst. These
hydrocarbons may
require further processing in order to be useful as base oils. For example,
the hydrocarbons
may be dewaxed, hydroisomerized, and/or hydrocracked using processes known to
a person of
ordinary skill in the art.
[0034] In further embodiments, the base oil comprises an unrefined oil, a
refined oil, a
rerefined oil, or a mixture thereof Unrefined oils are those obtained directly
from a natural or
synthetic source without further purification treatment. Non-limiting examples
of unrefined
oils include shale oils obtained directly from retorting operations, petroleum
oils obtained
directly from primary distillation, and ester oils obtained directly from an
esterification process
and used without further treatment. Refined oils are similar to the unrefined
oils except the
former have been further treated by one or more purification processes to
improve one or more
properties. Many such purification processes are known to those skilled in the
art such as
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solvent extraction, secondary distillation, acid or base extraction,
filtration, percolation, and
the like. Rerefined oils are obtained by applying to refined oils processes
similar to those used
to obtain refined oils. Such rerefined oils are also known as reclaimed or
reprocessed oils and
often are additionally treated by processes directed to removal of spent
additives and oil
breakdown products.
Anti-Fatigue Additive
[0035] The lubricating oil composition herein contains an anti-fatigue
additive. The anti-
fatigue additive is an alkyl polyol wherein the alkyl polyol has 2 to 20
carbon atoms such as
from 2 to 19 carbon atoms, 2 to 18 carbon atoms, 2 to 17 carbon atoms, 2 to 16
carbon atoms,
2 to 15 carbon atoms, 2 to 14 carbon atoms, 2 to 13 carbon atoms, 2 to 12
carbon atoms, 2 to
11 carbon atoms, 2 to 10 carbon atoms, 2 to 9 carbon atoms, and 2 to 8 carbon
atoms. The
alkyl polyol includes 2 or more alcohol groups such as 3 or more alcohol
groups, 4 or more
alcohol groups, and 5 or more alcohol groups. The term "alkyl", as used
herein, unless
otherwise specified, includes a saturated straight, branched, cyclic, primary,
secondary, or
tertiary hydrocarbon of Cl to C20.
[0036] Suitable alkyl polyols include glycerol, ethylene glycol, 3-amino-1,2-
propanediol,
1,2,4-butanetriol, 1,1,1,-tris(hydroxymethyl)propane, meso-erythritol, D-
sorbitol, xylitol, 2,2-
diethyl-1,3 -propane diol, 3-methoxy-1,2,-propanediol,
2,2-dimethy1-1,3-propanediol,
pentaerythritol, and polyvinyl alcohol. Suitable cyclic alkyl polyols include
myo-inositol, D-
(+)-xylose, and D-(+)-glucose. Other alkyl polyols include alcohol ethers such
as diglycerol,
triglycerol, diethylene glycol, triethylene glycol, dipentaerythritol, and
tripentaerythritol.
[0037] In some embodiments, the alkyl polyol is added to the lubricating oil
composition in an
amount that increases the fatigue time of the lubricating oil composition over
a comparable
fluid without the alkyl polyol according to the ZF bearing pitting test.
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[0038] The exact amount of the anti-fatigue additive may vary depending upon
the
composition and amount of the oil or lubricating viscosity, the specific
detergents and amounts,
and the other desired properties of the lubricating oil composition. In some
embodiments the
amount of anti-fatigue additive is at least about 0.001, or at least about
0.05, or at least about
0.1, or at least about 0.3, or at least about 0.4, or at least about 0.4, or
at least about 0.5, or at
least about 0.75, or at least about 1.0 wt. % up to about 1.5, or up to about
1.25, or up to about
1.0, or up to about 0.9, or up to about 0.8 wt. % based on the total weight of
the lubricating oil
composition.
Detergents
[0039] The lubricating oil composition comprises a metal sulfonate detergent.
The metal can
be any metal suitable for making sulfonate detergents. Non-limiting examples
of suitable
metals include alkali metals, alkaline earth metals and transition metals. In
some embodiments,
the metal is Ca, Mg, Ba, K, Na, Li or the like.
[0040] Generally, the amount of the detergent is from about 0.001 wt. % to
about 10 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.
[0041] Optionally, the lubricating oil composition may comprise additional
detergents
generally known in the art. Some suitable detergents have been described in
Mortier et al.,
"Chemistry and Technology of Lubricants," 2nd Edition, London, Springer,
Chapter 3, pages
75-85 (1996); and Leslie R. Rudnick, "Lubricant Additives: Chemistry and
Applications," New
York, Marcel Dekker, Chapter 4, pages 113-136 (2003), both of which are
incorporated herein
by reference. Examples of these detergents include phenates, salicylates,
phosphonates, and
the like.
[0042] In some embodiments the detergent comprises at least one high overbased
(TBN above
250 on an actives basis) sulfonate detergent such as high overbased calcium
sulfonate.
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[0043] Overbased metal detergents are generally produced by carbonating a
mixture of
hydrocarbons, detergent acid, for example: sulfonic acid, alkylhydroxybenzoate
etc., metal
oxide or hydroxides (for example calcium oxide or calcium hydroxide) and
promoters such as
xylene, methanol and water. For example, for preparing an overbased calcium
sulfonate, in
carbonation, the calcium oxide or hydroxide reacts with the gaseous carbon
dioxide to form
calcium carbonate. The sulfonic acid is neutralized with an excess of CaO or
Ca(OH)2, to form
the sulfonate.
[0044] Generally speaking, overbased detergents may be low overbased (LOB),
e.g., an
overbased salt having a TBN below 100 on an actives basis. In one aspect, the
TBN of a low
overbased salt may be from about 10 to about 100. In another aspect, the TBN
of a low
overbased salt may be from about 10 to about 80. Overbased detergents may be
medium
overbased (MOB), e.g., an overbased salt having a TBN from about 100 to about
250 on an
actives basis. In one aspect, the TBN of a medium overbased salt may be from
about 100 to
about 200. In another aspect, the TBN of a medium overbased salt may be from
about 125 to
about 175. Overbased detergents may be high overbased (HOB), e.g., an
overbased salt having
a TBN above 250 on an actives basis. In one aspect, the TBN of a high
overbased salt may be
from about 250 to about 800 on an actives basis.
[0045] In some embodiments, the lubricating oil composition comprises low
levels of sulfur
containing calcium phenates (e.g., about 40 mmol or less of Ca from sulfurized
phenates such
as 35 mmol or less, 30 mmol or less, 25 mmol or less, 20 mmol or less, 10 mmol
or less, 5
mmol or less and 0 mmol).
Other Additives
[0046] Optionally, the lubricating oil composition may further comprise at
least an additive or
a modifier (hereinafter designated as "additive") that can impart or improve
any desirable
property of the lubricating oil composition. Any additive known to a person of
ordinary skill
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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. In some embodiments, the additive can be
selected from the
group consisting of antioxidants, antiwear agents, detergents, rust
inhibitors, demulsifiers,
friction modifiers, multi-functional additives, viscosity index improvers,
pour point
depressants, foam inhibitors, metal deactivators, dispersants, corrosion
inhibitors, lubricity
improvers, thermal stability improvers, anti-haze additives, icing inhibitors,
dyes, markers,
static dissipaters, biocides and combinations thereof
[0047] A particularly suitable combination of additives comprises anti-fatigue
additive in the
amounts described above, a dispersant additive such as ethylene carbonate post
treated
bissuccinimide, an antiwear additive such as zinc dialkyl diothiophosphate
such as one derived
from a primary alcohol, and a detergent composition as described above
comprising at least
one high overbased sulfonate detergent (e.g., a high overbased calcium
sulfonate). Optionally,
the lubricating oil composition may comprise an additional detergent (e.g., a
phenate
detergent). The zinc dialkyl dithiophosphate is a primary, secondary zinc
dialkyl
dithiophosphate, or a combination thereof and may be present at 3 wt. % or
less (e.g., 0.1 to
1.5 wt. %, or 0.5 to 1.0 wt %) of the lubricating oil composition. The
dispersant such as
ethylene carbonate post treated bissuccinimide may be present at 0.1 to 10 wt.
% (e.g., 0.5 to
8, 0.7 to 7, 0.7 to 6, 0.7 to 6, 0.7 to 5, 0.7 to 4 wt. %), based on the total
weight ofthe lubricating
oil composition.
[0048] In general, the concentration of each of the additives in the
lubricating oil composition,
when used, may range from about 0.001 wt. % to about 10 wt. %, from about 0.01
wt. % to
about 5 wt. %, or from about 0.1 wt. % to about 2.5 wt. %, based on the total
weight of the
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lubricating oil composition. Further, the total amount of the additives in the
lubricating oil
composition may range from about 0.001 wt. % to about 20 wt. %, from about
0.01 wt. % to
about 10 wt. %, or from about 0.1 wt. % to about 5 wt. %, based on the total
weight of the
lubricating oil composition.
Anti-wear agents
[0049] Optionally, the lubricating oil composition disclosed herein can
comprise one or more
anti-wear agents. In some embodiments, the lubricating oil composition is free
or substantially
free of sulfur-containing anti-wear composition.
[0050] Anti-wear agents reduce wear of metal parts. Suitable anti-wear agents
include
dihydrocarbyl dithiophosphate metal salts such as zinc dihydrocarbyl
dithiophosphates
(ZDDP) of the following structure:
Zn[S-P(=S)(0R1)(0R2)12
wherein Rl and R2 may be the same of different hydrocarbyl radicals having
from 1 to 18 (e.g.,
2 to 12) carbon atoms and including radicals such as alkyl, alkenyl, aryl,
arylalkyl, alkaryl and
cycloaliphatic radicals. Particularly preferred as R' and R2 groups are alkyl
groups having
from 2 to 8 carbon atoms (e.g., the alkyl radicals may be ethyl, n-propyl,
isopropyl, n-butyl,
isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, 2-ethylhexyl). In
order to obtain oil
solubility, the total number of carbon atoms (i.e., R' + R2) will be at least
5. The zinc
dihydrocarbyl dithiophosphate can therefore comprise zinc dialkyl
dithiophosphates. The zinc
dialkyl dithiophosphate is a primary, secondary zinc dialkyl dithiophosphate,
or a combination
thereof ZDDP may be present at 3 wt. % or less (e.g., 0.1 to 1.5 wt. %, or 0.5
to 1.0 wt %) of
the lubricating oil composition.
Dispersants
[0051] Optionally, the lubricating oil composition disclosed herein can
further comprise a
dispersant. Dispersants maintain in suspension materials resulting from
oxidation during
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engine operation that are insoluble in oil, thus preventing sludge
flocculation and precipitation
or deposition on metal parts. Dispersants useful herein include nitrogen-
containing, ashless
(metal-free) dispersants known to effective to reduce formation of deposits
upon use in gasoline
and diesel engines. Suitable dispersants include hydrocarbyl succinimides,
hydrocarbyl
succinamides, mixed ester/amides of hydrocarbyl-substituted succinic acid,
hydroxyesters of
hydrocarbyl-substituted succinic acid, and Mannich condensation products of
hydrocarbyl-
substituted phenols, formaldehyde and polyamines. Also suitable are
condensation products of
polyamines and hydrocarbyl-substituted phenyl acids. Mixtures of these
dispersants can also
be used.
[0052] Basic nitrogen-containing ashless dispersants are well-known
lubricating oil additives
and methods for their preparation are extensively described in the patent
literature. Preferred
dispersants are the alkenyl succinimides and succinamides where the alkenyl-
substituent is a
long-chain of preferably greater than 40 carbon atoms. These materials are
readily made by
reacting a hydrocarbyl-substituted dicarboxylic acid material with a molecule
containing amine
functionality. Examples of suitable amines are polyamines such as polyalkylene
polyamines,
hydroxy-substituted polyamines and polyoxyalkylene polyamines. As is known in
the art, the
dispersants may be post-treated (e.g., with a boronating agent, ethylene
carbonate, or a cyclic
carbonate). Nitrogen-containing ashless (metal-free) dispersants are basic,
and contribute to
the TBN of a lubricating oil composition to which they are added, without
introducing
additional sulfated ash. Dispersants may be present at 0.1 to 10 wt. % (e.g.,
0.5 to 8, 0.7 to 7,
0.7 to 6, 0.7 to 6, 0.7 to 5, 0.7 to 4 wt. %), based on an actives level, of
the lubricating oil
composition. Nitrogen from the dispersants is present from greater than 0.0050
to 0.30 wt. %
(e.g., greater than 0.0050 to 0.10 wt. %, 0.0050 to 0.080 wt. %, 0.0050 to
0.060 wt. %, 0.0050
to 0.050 wt. %, 0.0050 to 0.040 wt. %, 0.0050 to 0.030 wt. %) based on the
weight of the
dispersants in the finished oil.
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Antioxidants
[0053] Optionally, the lubricating oil composition disclosed herein can
further comprise an
additional antioxidant that can reduce or prevent the oxidation of the base
oil. Any antioxidant
known by a person of ordinary skill in the art may be used in the lubricating
oil composition.
Non-limiting examples of suitable antioxidants include amine-based
antioxidants (e.g., alkyl
diphenylamines, phenyl-.alpha.-naphthylamine, alkyl or aralkyl substituted
phenyl-.alpha.-
naphthylamine, alkylated p-phenylene diamines, tetramethyl-
diaminodiphenylamine and the
like), phenolic antioxidants (e.g., 2-tert-butylphenol, 4-methyl-2,6-di-tert-
butylphenol, 2,4,6-
tri-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol,
4,4'-methylenebis-(2,6-
di-tert-butylphenol), 4,4'-thiobis(6-di-tert-butyl-o-cresol) and the like),
sulfur-based
antioxidants (e.g., dilaury1-3,3'-thiodipropionate, sulfurized phenolic
antioxidants and the like),
phosphorous-based antioxidants (e.g., phosphites and the like), zinc
dithiophosphate, oil-
soluble copper compounds and combinations thereof. The amount of the
antioxidant 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.
Some suitable antioxidants have been described in Leslie R. Rudnick,
"Lubricant Additives:
Chemistry and Applications," New York. Marcel Dekker, Chapter 1, pages 1-28
(2003), which
is incorporated herein by reference.
Friction Modifiers
[0054] The lubricating oil composition disclosed herein can optionally
comprise a friction
modifier 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
tri-alkyl substituted phosphoric acids or phosphonic acids; derivatives (e.g.,
esters, amides,
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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, the friction modifier is selected
from the group
consisting of aliphatic amines, ethoxylated aliphatic amines, aliphatic
carboxylic acid amides,
ethoxylated aliphatic ether amines, aliphatic carboxylic acids, glycerol
esters, aliphatic
carboxylic ester-amides, fatty imidazolines, fatty tertiary amines, wherein
the aliphatic or fatty
group contains more than about eight carbon atoms so as to render the compound
suitably oil
soluble. In other embodiments, the friction modifier comprises an aliphatic
substituted
succinimide formed by reacting an aliphatic succinic acid or anhydride with
ammonia or a
primary amine. The amount of the friction modifier may vary from about 0.01
wt. % to about
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. Some suitable
friction modifiers
have been described in Mortier et al., "Chemistry and Technology of
Lubricants," 2nd Edition,
London, Springer, Chapter 6, pages 183-187 (1996); and Leslie R. Rudnick,
"Lubricant
Additives: Chemistry and Applications," New York, Marcel Dekker, Chapters 6
and 7, pages
171-222 (2003), both of which are incorporated herein by reference.
Pour Point Depressants
[0055] The lubricating oil composition disclosed herein can optionally
comprise a pour point
depressant that can lower the pour point of the lubricating oil composition.
Any pour point
depressant known by a person of ordinary skill in the art may be used in the
lubricating oil
composition. Non-limiting examples of suitable pour point depressants
include
polymethacrylates, alkyl acrylate polymers, alkyl methacrylate polymers,
di(tetra-paraffin
phenol)phthalate, condensates of tetra-paraffin phenol, condensates of a
chlorinated paraffin
with naphthalene and combinations thereof. In some embodiments, the pour point
depressant
comprises an ethylene-vinyl acetate copolymer, a condensate of chlorinated
paraffin and
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phenol, polyalkyl styrene or the like. The amount of the pour point depressant
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. Some
suitable pour point depressants have been described in Mortier et al.,
"Chemistry and
Technology of Lubricants," 2nd Edition, London, Springer, Chapter 6, pages 187-
189 (1996);
and Leslie R. Rudnick, "Lubricant Additives: Chemistry and Applications," New
York, Marcel
Dekker, Chapter 11, pages 329-354 (2003), both of which are incorporated
herein by reference.
Demulsifiers
[0056] The lubricating oil composition disclosed herein can optionally
comprise a demulsifier
that can promote oil-water separation in lubricating oil compositions that are
exposed to water
or steam. Any demulsifier known by a person of ordinary skill in the art may
be used in the
lubricating oil composition. Non-limiting examples of suitable demulsifiers
include anionic
surfactants (e.g., alkyl-naphthalene sulfonates, alkyl benzene sulfonates and
the like), nonionic
alkoxylated alkylphenol resins, polymers of alkylene oxides (e.g.,
polyethylene oxide,
polypropylene oxide, block copolymers of ethylene oxide, propylene oxide and
the like), esters
of oil soluble acids, polyoxyethylene sorbitan ester and combinations thereof
The amount of
the demulsifier 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. Some suitable demulsifiers have been described in
Mortier et al.,
"Chemistry and Technology of Lubricants," 2nd Edition. London, Springer,
Chapter 6, pages
190-193 (1996), which is incorporated herein by reference.
Foam Inhibitors
[0057] The lubricating oil composition disclosed herein can optionally
comprise a foam
inhibitor or an anti-foam that can break up foams in oils. Any foam inhibitor
or anti-foam
known by a person of ordinary skill in the art may be used in the lubricating
oil composition.
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Non-limiting examples of suitable anti-foams include silicone oils or
polydimethylsiloxanes,
fluorosilicones, alkoxylated aliphatic acids, polyethers (e.g., polyethylene
glycols), branched
polyvinyl ethers, alkyl acrylate polymers, alkyl methacrylate polymers,
polyalkoxyamines and
combinations thereof In some embodiments, the anti-foam comprises glycerol
monostearate,
polyglycol palmitate, a trialkyl monothiophosphate, an ester of sulfonated
ricinoleic acid,
benzoylacetone, methyl salicylate, glycerol monooleate, or glycerol dioleate.
The amount of
the anti-foam 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. Some suitable anti-foams have been described in Mortier et
al., "Chemistry
and Technology of Lubricants," 2nd Edition, London, Springer, Chapter 6, pages
190-193
(1996), which is incorporated herein by reference.
Corrosion Inhibitors
[0058] The lubricating oil composition disclosed herein can optionally
comprise a corrosion
inhibitor that can reduce corrosion. Any corrosion inhibitor known by a person
of ordinary
skill in the art may be used in the lubricating oil composition. Non-limiting
examples of
suitable corrosion inhibitor include half esters or amides of dodecylsuccinic
acid, phosphate
esters, thiophosphates, alkyl imidazolines, sarcosines and combinations
thereof The amount
of the corrosion inhibitor 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. Some suitable corrosion inhibitors have been
described in
Mortier et al., "Chemistry and Technology of Lubricants," 2nd Edition, London,
Springer,
Chapter 6, pages 193-196 (1996), which is incorporated herein by reference.
Extreme Pressure Agents
[0059] The lubricating oil composition disclosed herein can optionally
comprise an extreme
pressure (EP) agent that can prevent sliding metal surfaces from seizing under
conditions of
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extreme pressure. Any extreme pressure agent known by a person of ordinary
skill in the art
may be used in the lubricating oil composition. Generally, the extreme
pressure agent is a
compound that can combine chemically with a metal to form a surface film that
prevents the
welding of asperities in opposing metal surfaces under high loads. Non-
limiting examples of
suitable extreme pressure agents include sulfurized animal or vegetable fats
or oils, sulfurized
animal or vegetable fatty acid esters, fully or partially esterified esters of
trivalent or
pentavalent acids of phosphorus, sulfurized olefins, dihydrocarbyl
polysulfides, sulfurized
Diels-Alder adducts, sulfurized dicyclopentadiene, sulfurized or co-sulfurized
mixtures of fatty
acid esters and monounsaturated olefins, co-sulfurized blends of fatty acid,
fatty acid ester and
alpha-olefin, functionally-substituted dihydrocarbyl polysulfides, thia-
aldehydes, thia-ketones,
epithio compounds, sulfur-containing acetal derivatives, co-sulfurized blends
of terpene and
acyclic olefins, and polysulfide olefin products, amine salts of phosphoric
acid esters or
thiophosphoric acid esters and combinations thereof The amount of the extreme
pressure
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. Some suitable extreme pressure agents have been described in
Leslie R. Rudnick,
"Lubricant Additives: Chemistry and Applications," New York, Marcel Dekker,
Chapter 8,
pages 223-258 (2003), which is incorporated herein by reference.
Rust Inhibitors
[0060] The lubricating oil composition disclosed herein can optionally
comprise a rust
inhibitor that can inhibit the corrosion of ferrous metal surfaces. Any rust
inhibitor known by
a person of ordinary skill in the art may be used in the lubricating oil
composition. Non-limiting
examples of suitable rust inhibitors include oil-soluble monocarboxylic acids
(e.g., 2-
ethylhexanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid,
linoleic acid, linolenic
acid, behenic acid, cerotic acid and the like), oil-soluble polycarboxylic
acids (e.g., those
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produced from tall oil fatty acids, oleic acid, linoleic acid and the like),
alkenylsuccinic acids
in which the alkenyl group contains 10 or more carbon atoms (e.g.,
tetrapropenylsuccinic acid,
tetradecenylsuccinic acid, hexadecenylsuccinic acid, and the like); long-chain
alpha,omega-
dicarboxylic acids having a molecular weight in the range of 600 to 3000
daltons and
combinations thereof The amount of the rust inhibitor 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.
[0061] Other non-limiting examples of suitable rust inhibitors include
nonionic
polyoxyethylene surface active agents such as polyoxyethylene lauryl ether,
polyoxyethylene
higher alcohol ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene
octyl phenyl ether,
polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl ether,
polyoxyethylene sorbitol
monostearate, polyoxyethylene sorbitol mono-oleate, and polyethylene glycol
mono-oleate.
Further non-limiting examples of suitable rust inhibitor include stearic acid
and other fatty
acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of
heavy sulfonic acid,
partial carboxylic acid ester of polyhydric alcohol, and phosphoric ester.
Multifunctional Additives
[0062] In some embodiments, the lubricating oil composition comprises at least
a
multifunctional additive. Some non-limiting examples of suitable
multifunctional additives
include sulfurized oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum
organophosphorodithioate, oxymolybdenum monoglyceride, oxymolybdenum
diethylate
amide, amine-molybdenum complex compound, and sulfur-containing molybdenum
complex
compound.
Viscosity Index Improvers
[0063] In certain embodiments, the lubricating oil composition comprises at
least a viscosity
index improver. Some non-limiting examples of suitable viscosity index
improvers include
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polymethacrylate type polymers, ethylene-propylene copolymers, styrene-
isoprene
copolymers, hydrated styrene-isoprene copolymers, polyisobutylene, and
dispersant type
viscosity index improvers.
Metal Deactivators
[0064] In some embodiments, the lubricating oil composition comprises at least
a metal
deactivator. Some non-limiting examples of suitable metal deactivators include
disalicylidene
propylenediamine, triazole derivatives, thiadiazole derivatives, and
mercaptobenzimidazoles.
Additive Concentrate Formulations
[0065] The additives disclosed herein may be in the form of an additive
concentrate having
more than one additive. The additive concentrate may comprise a suitable
diluent, such as a
hydrocarbon oil of suitable viscosity. Such diluent can be selected from the
group consisting
of natural oils (e.g., mineral oils), synthetic oils and combinations thereof
Some non-limiting
examples of the mineral oils include paraffin-based oils, naphthenic-based
oils, asphaltic-based
oils and combinations thereof Some non-limiting examples of the synthetic base
oils include
polyolefin oils (especially hydrogenated alpha-olefin oligomers), alkylated
aromatic,
polyalkylene oxides, aromatic ethers, and carboxylate esters (especially
diester oils) and
combinations thereof In some embodiments, the diluent is a light hydrocarbon
oil, both natural
or synthetic. Generally, the diluent oil can have a viscosity from about 13
centistokes to about
35 centistokes at 40 C.
[0066] Generally, it is desired that the diluent readily solubilizes the
lubricating oil soluble
additive and provides an oil additive concentrate that is readily soluble in
the lubricant base oil
stocks or fuels. In addition, it is desired that the diluent not introduce any
undesirable
characteristics, including, for example, high volatility, high viscosity, and
impurities such as
heteroatoms, to the lubricant base oil stocks and thus, ultimately to the
finished lubricant or
fuel.
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[0067] The present application further provides an oil soluble additive
concentrate composition
comprising an inert diluent and from 2.0% to 90% by weight, preferably 10% to
50% by weight
based on the total concentrate, of an oil soluble additive composition
according to the present
application.
[0068] The functional fluids comprising the additives described above may be
employed in a
method of increasing the fatigue time of a bearing comprising contacting a
metal surface with
a functional fluid.
[0069] The following examples are presented to exemplify embodiments but are
not intended
to limit the application 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 application. Specific details described
in each example
should not be construed as necessary features.
EXAMPLES
[0070] The following examples are intended for illustrative purposes only and
do not limit in
any way the scope.
ZF Bearing Pitting Test
[0071] Bearing performance is evaluated using ZF specification 03C bearing
pitting test 0000
702 232. This test uses FE 8 roller thrust bearings with an axial for of 68 kN
revolving at 300
rpm. The temperature is 100 C. In this test, the length of time to failure is
measured and
failure is determined when vibration becomes so severe that metal pieces get
dislodged from
the bearing or the case that contacts the bearing and the FE8 test rig
automatically shuts down.
The removed metal leaves pits in the bearing or the case. In order to pass the
test for the ZF
03C specification, the minimal length of time to failure is 300 hours. The
maximum amount
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of time the test is allowed to run is 750 hours. The ZF bearing pitting test
is available from
Assmann Laboratories, Aachen, Germany.
Baseline Formulation
[0072] The baseline formulation includes the following:
(i) 1 wt. % of an ethylene carbonate capped dispersant;
(ii) 1.28 wt. % of an oil concentrate of a zinc dithiophosphate derived from a
primary
alcohol containing 7.3 wt. % phosphorus;
(iii) 0.79 wt. % of a 320 TBN oil concentrate of a Ca sulfonate detergent;
(iv) 0.5 wt. % of a pour point depressant;
(v) 0.6 wt. % of a seal swell additive;
(vi) 0.04 wt. % of foam inhibitors;
(vii) The balance, a Group II base oil at 10W viscosity.
COMPARATIVE EXAMPLE A
[0073] Comparative Example A was prepared using the above baseline formulation
with the
addition of 1.46% wt. % (35 mmol Ca) of a sulfurized highly overbased calcium
phenate with
a TBN of 263.
COMPARATIVE EXAMPLE B
[0074] Comparative example B was prepared using the above baseline formulation
with the
addition of 1.88 wt. % (45 mmol Ca) of a highly sulfurized overbased calcium
phenate with a
TBN of 263.
COMPARATIVE EXAMPLE C
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[0075] Comparative example C was prepared using the above baseline formulation
with the
addition of 2.29 wt. % (55 mmol Ca) of a highly sulfurized overbased calcium
phenate with a
TBN of 263.
[0076] Table 1 summarizes Comparative Examples A, B, and C. Table 1 also shows
that in
the absence of glycerol, a threshold amount of sulfurized phenate detergent is
required to pass
the ZF FE 8 Bearing Pitting Test. Increasing the amount of sulfurized phenate
improved the
ZF test results.
TABLE 1
Comparative Comparative Comparative
Example A Example B Example C
% Sulfurized
Phenate 1.46 1.88 2.29
Concentration
mmol of Ca from
35 45 55
Sulfurized Phenate
% glycerol 0
0 0
Hours to Failure 96, 94, 88
340, 287 464, 429
Average Hours to
93 314 447
failure
ZF Test Pass/Fail Fail Pass Pass
EXAMPLES 1 TO 6
[0077] A lubricating oil composition was prepared utilizing the above baseline
formulation
with the addition of 1.46 wt. % (35 mmol Ca) of a sulfurized highly overbased
calcium phenate
with a TBN of 263. Glycerol was added into the formulations as a wt. % as
shown in Table 2
below.
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TABLE 2
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
% Sulfurized
Phenate 1.46 1.46 1.46 1.46 1.46 1.46
Concentration
mmol of Ca from
Sulfurized 35 35 35 35 35 35
Phenate
% glycerol 0.01 0.03 0.05 0.1 0.15 0.25
750, 750,
Hours to Failure
104,119 309,232 368,498 691 750,750
750,750
Average Hours to
110 271 433 730 750 750
failure
ZF Test Pass/Fail Fail Fail Pass Pass Pass Pass
[0078] Table 2 shows that the addition of glycerol at very low treat rates
surprisingly and
unexpectedly allowed the passing of the ZF FE 8 Bearing Pitting Test even at
below threshold
levels of sulfurized phenate. Increasing the glycerol treat rate significantly
improved the ZF
test performance to the maximum duration of the ZF test (750 hours).
EXAMPLE 7
[0079] Example 7 was prepared using the above baseline formulation with the
addition of 1.04
wt. % (25 mmol Ca) of a highly sulfurized overbased calcium phenate with a TBN
of 263 and
0.25 wt. % glycerol.
EXAMPLE 8
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[0080] Example 8 was prepared using the above baseline formulation with the
addition of 0.42
wt. % (10 mmol Ca) of a highly sulfurized overbased calcium phenate with a TBN
of 263 and
0.25 wt. % glycerol.
EXAMPLE 9
[0081] Example 9 was prepared using the above baseline formulation with the
addition of 0.25
wt. % of glycerol.
EXAMPLE 10
[0082] Example 10 was prepared using the above baseline formulation with the
addition of
0.20 wt. % of glycerol.
EXAMPLE 11
[0083] Example 11 was prepared using the above baseline formulation with the
addition of
0.15 wt. % of glycerol.
EXAMPLE 12
[0084] Example 12 was prepared using the above baseline formulation with the
addition of
0.10% wt. % of glycerol.
EXAMPLE 13
[0085] Example 13 was prepared using the above baseline formulation with the
addition of
0.05 wt. % of glycerol.
EXAMPLE 14
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[0086] Example 14 was prepared using the above baseline formulation with the
addition of
0.03 wt. % of glycerol.
[0087] Examples 7 to 14 are summarized in Table 3 below.
TABLE 3
Example Example Example Example Example Example Example Example
7 8 9 10 11 12 13 14
% Sulfurized
Phenate 1.04 0.42 0 0 0 0 0 0
Concentration
mmol of Ca
from
25 10 0 0 0 0 0 0
Sulfurized
Phenate
% glycerol 0.25 0.25 0.25 0.2 0.15 0.1 0.05
0.03
Hours to
Failure 750, 750 577, 750 750, 750 750, 750 750, 750 485, 498 264, 240
186, 170
Average Hours
750 664 750 750 750 492 252
178
to failure
Pass/Fail Pass Pass Pass Pass Pass Pass Fail
Fail
[0088] As shown in Table 3, the addition of glycerol allows passing of the ZF
FE 8 Bearing
Pitting test at very low treat rates of sulfurized phenate or even in the
absence of sulfurized
phenate altogether. In fact, maximum ZF test performance can be achieved with
very little
amounts of glycerol and complete removal of sulfurized phenate.
EXAMPLES 15 - 19
[0089] Examples 15 ¨ 19 were prepared using the above baseline formulation
without the
presence of the zinc dithiophosphate and with the wt. % of glycerol as shown
in Table 4.
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[0090] Surprisingly, improved bearing pitting results were observed in samples
containing
low amounts of zinc dithiophosphate or even in the absence of zinc
dithiophosphate. In these
samples, glycerol is essentially the only anti-fatigue component. This was
observed even at
very low amounts of glycerol (e.g., down to 0.05% glycerol).
[0091] As shown in Table 4, equivalent amounts of glycerol, especially at the
low treat rates
gave the maximum 750 hours of performance in the ZF FE 8 Bearing Pitting Test.
Also, for
example, comparing Example 13 with 0.05 wt. % glycerol and with 1.28% Zn
dithiophosphate
gave a failing result of 252 hours, whereas the equivalent zinc-free Example
19 gave a
maximum passing result of 750 hours.
TABLE 4
Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex.
10 11 12 13 14 15 16 17 18 19
% Sulfurized 0 0 0 0 0 0 0 0 0 0
Phenate
Concentration
Zn 1.28 1.28 1.28 1.2 1.28 0 0 0 0 0
dithiophosphate 8
Glycerol (wt %) 0.2 0.15 0.1 0.0 0.03 0.25 0.2
0.15 0.1 0.05
5
Hours to Failure 750, 750,
485, 264 186, 750, 750, 750, 750, 750,
750 750 498 240 170 750 750 750 664 750
Average hours to 750 750 492 252
178 750 750 750 707 750
failure
ZF Test Pass
Pass Pass Fail Fail Pass Pass Pass Pass Pass
(Pass/Fail)
[0092] It will be understood that various modifications may be made to the
embodiments
disclosed herein. Therefore, the above description should not be construed as
limiting, but
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31
merely as exemplifications of embodiments of the invention. For example, the
functions
described above and implemented for operating are for illustration purposes
only. Other
arrangements and methods may be implemented by those skilled in the art
without departing
from the scope and spirit of this application. Moreover, those skilled in the
art will envision
other modifications within the scope and spirit of the claims appended hereto.
