Note: Descriptions are shown in the official language in which they were submitted.
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ULTRA-LOW SAPS LUBRICANTS FOR INTERNAL COMBUSTION ENGINES
FIELD OF THE INVENTION
The present invention generally relates to Ultra-Low SAPS lubricants for
Internal
Combustion Engines.
BACKGROUND OF THE INVENTION
When formulating motor oils for use in an automotive engine, there are a
number of
seemingly conflicting drivers which must be balanced. On the one hand there is
a desire to
formulate with additives which contain metals, sulfur and phosphorus because
they have a
proven track record for performance. These additives are known to impart wear
and corrosion
resistance to the oil and reduce deposit formation in the engine. This
resistance is necessary
as the demand for long life lubricants increases. However, the use of these
additives is
constrained by environmental legislation.
During the 1950s and 1960s a number of studies were undertaken to determine
the
source of air pollution which was becoming a problem in metropolitan areas.
Automotive
exhaust was indicated as a contributing factor. As a result, laws were put in
place at the
national and state levels to regulate the allowable limits for emissions of
certain regulated
chemicals. In response to these regulations, engine manufacturers have
introduced exhaust
gas after-treatment devices to clean up the emitted exhaust gas of internal
combustion
engines. Commonly used on spark ignited engines are oxidation catalysts, and
commonly
used on compression ignition engines are Diesel Particulate Filters (DPF)
combined with an
oxidation catalyst, and NOx reduction catalysts. The oxidation catalysts are
used to decrease
carbon monoxide (CO) and hydrocarbon emissions by oxidation. The catalysts
utilized can be
poisoned when they interact with certain metals or phosphorus. Limitations on
sulfated ash,
phosphorus, and sulfur levels (SAPS) in motor oils have been put in place to
enable the use of
exhaust gas after-treatment devices.
Commercial lubricants for internal combustion engines are commonly formulated
in
such a way that the SAPS content of the lubricant falls just below those
limits. It is assumed
by those skilled in the art of formulating engine lubricants that lowering the
treat rates of
SAPS containing performance additives far below those restrictions causes the
performance
of the lubricant to deteriorate to the point of unacceptability.
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In addition to the CO and particle limits on emissions, there are efforts
being made to
reduce carbon dioxide (CO2) emissions from vehicles. As CO2 is a product of
the combustion
of hydrocarbon based fuels, the most direct means to reduce CO2 emissions is
to reduce fuel
consumption. Deterioration of exhaust gas after-treatment devices can lead to
increased fuel
consumption. Accumulation of sulfated ash in diesel particulate filters can
lead to increased
engine backpressure and consequent fuel consumption increase. Also, when NOx
[a generic
term for mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide)
reduction
catalysts are poisoned by sulfur, regeneration requires additional fuel
injections, causing the
total fuel consumption to increase. For these reasons the question of how
deterioration of
exhaust gas after-treatment devices can be minimized is more important than
ever.
In general, the following patent art teaches elements of the proposed
invention, but
none are capable of solving the complex problem of high temperature corrosion,
wear and
deposit formation which result when Sulfated Ash, Phosphorous, and Sulfur
(SAPS) are
taken to nearly zero levels.
U. S. Patent Application No. 20100152079 discloses a lubricant composition
containing an oil of lubricating viscosity, a N,N,N',N'-tetramethyl-
naphthalene-1,8-diamine,
and at least one additive selected from antioxidants, detergents, dispersants
which together
provide superior oxidation inhibition for automotive and truck crankcase
lubricants.
U. S. Patent Application No. 20080139425 discloses an additive package, useful
in a
lubricant composition, which comprises: a diluent; and a hydrocarbyl
substituted triazole
compound, with the proviso that the lubricant is substantially free of
compounds containing
phosphorus. This additive package is selected for its ability to protect lead
and silver bearings
found in medium speed diesel engines including railroad engines.
European Patent Application No. 0758016 discloses an additive combination
comprising an aromatic amine anti-oxidant and a "B" compound. The combination
contains 1
pt. wt. of boron per 250 pts. of nitrogen in the amine. The oils exemplified
are blended with a
standard additive package and are not essentially free of SAPS derived from
the components.
U. S. Patent Application No. 20080020953 discloses a lubricating oil
composition
which contains lube base oil comprising mineral oil and/or synthetic oil, ash-
free dispersant
(in mass%) (0.01-0.14) based on nitrogen amount, antioxidant and sulfated ash
(1.2 or less).
The antioxidant contains dialkyldiphenyl amine (0.3-5) and hindered phenol
compound (0-
2.5). The dispersant contains alkenyl- or alkyl-succinimide and/or boron
compound
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derivative (0.05 or less) in terms of nitrogen amount. All example oils
contain approximately
1% Sulfated Ash (SASH).
U. S. Patent No. 7,026,273 discloses a crankcase lubricating oil composition,
for an
internal combustion engine, which comprises an admixture of oil and boron-
containing
additive, and preset amounts of phosphorus and sulfur. This patent family
teaches lubricating
oil compositions containing (a) a boron-containing additive and one or more co-
additives,
wherein the lubricating oil composition has greater than 200 ppm by mass of
boron, less than
600 ppm by mass of phosphorus and less than 4000 ppm by mass of sulfur, based
on the mass
of the oil composition. All example lubricants contain approximately 1% SASH.
U. S. Patent Application No. 20060058200 discloses a lubricating oil
composition for
internal combustion engines, which contains a major amount of oil of
lubricating viscosity,
(a) at least one nitrogen-containing dispersant, the dispersant providing to
the oil a nitrogen
content of at least 0.075 wt. % nitrogen, the dispersant having a polyalkenyl
backbone which
has a molecular weight range of about 900 to 3000, and (b) an oil soluble or
oil dispersible
source of boron, present in an amount so as to provide a ratio of wt. %
nitrogen to wt. %
boron in the oil composition of about 3:1 to 5:1, wherein said lubricating oil
composition has
a sulfur content of up to 0.3 wt. %, a phosphorus content of up to 0.08 wt. %,
a sulfated ash
content of up to 0.80 wt. %. These oils are low SAPS, but not significantly
below the current
mandated levels. They still contain ZnDTP and metal detergents.
Japanese Patent No. 2922675 discloses a lubricating oil composition for coping
with
strict regulation of exhaust gas which contains 0.5-8 wt.% a (3,5-di-tert-
buty1-4-
hydroxyphenol) carboxylic acid alkyl ester(s) as an ash-free cleaner, 3-12
wt.% succinimide
type ash-free dispersant(s) and 0.1-3 wt.% phenol type ash-free antioxidant(s)
in a lubricating
base oil comprising a mineral and a synthetic oil(s). These lubricants are
designed to not
precipitate when in contact with methanol fuel.
U. S. Patent Application No. 20080020952 discloses a lubricant oil composition
for
contacting metal materials containing lead which comprises a lubricant base
oil, an optional
zinc dithiophosphate present in 0.08 wt% or less, and an additive selected
from organic
molybdenum compound excluding molybdenum thiophosphate, boric acid ester
and/or
derivatives, a mixture of the two, or organic molybdenum compound, boric acid
modified
alkyl or alkenyl succinic acid imide. These oils are low in Zn salts, but
still contain metallic
detergents.
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U. S. Patent Application No. 20060009366 discloses an oil composition for
lubricating internal combustion engines which comprises base oil and at least
1.4 wt% of an
aminic and/or phenolic antioxidant, wherein said lubricating oil composition
is phosphorus
free. These lubricants are formulated to be free of phosphorus antiwear
additives, but are not
free of metallic detergents. They are neither low ash nor low sulfur.
U. S. Patent Application No. 20040106527 discloses a lubricating oil
composition for
use in internal combustion engines, used along with a gasoline fuel having
sulfur content of
less than 10 ppm by weight, which has a phosphorous content of no more than
0.05 wt.%.
These lubricants are again low P without limiting sulfur or ash.
Although some of these references address one problem that occurs when the
SAPS
levels in a lubricant are limited, commercial lubricants must pass a battery
of tests to be
qualified. None of the references above address the multitude of high
temperature corrosive
wear and deposition issues which an oil needs to face in order to be qualified
for sale. For a
real solution to the problem of delivering low SAPS oils, it is desirable to
be able to balance
protection of the exhaust gas after treatment system with the performance
expected of a
modern lubricant in order to be truly viable.
SUMMARY OF THE INVENTION
With the existing limitations of Low SAPS, all applicable emission
requirements for
modern engines can be met. The currently existing lubricants have Low SAPS
restrictions
including: sulfated ash limits of <0.8 wt% for PCMO (Passenger Car Motor Oil)
or <1.0 wt%
for HDEO (Heavy Duty Engine Oil); phosphorus limits of <0.08 wt% for both PCMO
and
HDEO; and sulfur limits of <0.3 wt% for both PCMO and HDEO.
If exhaust gas after-treatment devices are harmed by sulfur, phosphorus and
sulfated
ash, then minimizing SAPS levels should maximize the lifetime of the exhaust
gas after-
treatment devices. An evaluation was done to determine which lubrication
performance gaps
arise when a conventional fully formulated lubricant is stripped of all the
performance
enhancing additives that contribute to SAPS. As expected, the performance
tests run on those
SAPS free lubricants indicate clearly unacceptable performance. However, with
the
subsequent addition of alternative performance enhancing additives which do
not contribute
to SAPS or only contribute minor amounts of SAPS, Ultra-Low SAPS experimental
lubricants were created which, much to our surprise, gave acceptable
performance. The
resultant prototype lubricants consist of components which are built up of the
elements H, 0,
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N, and C, with very minor amounts of other elements. In some embodiments, SAPS
levels
derived from the components in the additive package can be essentially zero.
"Ultra-Low SAPS' lubricating oil compositions are defined as: lubricating oil
compositions wherein Sulfur is present at less than 1000 ppm, Phosphorous is
present at less
than 300 ppm, and Sulfated Ash is present at less than 0.25 wt%. In some
embodiments S
(Sulfur) is present at <1000 ppm, <800 ppm, <500 ppm, <300 ppm, <100 ppm, < 50
ppm,
<10 ppm, and could be zero; P (Phosphorous) is present at <300 ppm, <200 ppm,
<100 ppm,
<50 ppm, <10 ppm, and could be zero; and Sulfated Ash is present as <0.25 wt%,
<0.20 wt%,
<0.15 wt%, <0.10 wt%, <0.05wt%, <0.01 wt% and could be 0 wt% in the finished
lubricant.
In accordance with one embodiment of the present invention, there is provided
an
ultra-low SAPS lubricating oil composition comprising:
an oil of lubricating viscosity;
a borated dispersant supplying at least 500 ppm boron to said lubricating oil
composition;
an ashless peroxide decomposer present at a treat rate of from about 0.4 to
5.0 wt%;
a metal deactivator wherein the metal deactivator is present at a treat rate
of greater than 0.08
wt%;
wherein said lubricating oil composition contains less than 1000 ppm sulfur
less than 300
ppm phosphorus and less than 0.25 wt% sulfated ash.
In accordance with another embodiment of the present invention, there is
provided a
method of lubricating an engine with an ultra-low SAPS lubricating oil
composition
comprising:
an oil of lubricating viscosity;
a borated dispersant supplying at least 500 ppm boron to said lubricating oil
composition;
an ashless peroxide decomposer present at a treat rate of from about 0.4 to
5.0 wt%;
a metal deactivator wherein the metal deactivator is present at a treat rate
of greater than 0.08
wt%;
wherein said lubricating oil composition contains less than 1000 ppm sulfur,
less than 300
ppm phosphorus and <0.25 wt% sulfated ash.
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DETAILED DESCRIPTION OF THE INVENTION
In general, provided herein is a process for preparing an ultra-low SAPS
lubricating
oil composition comprising:
an oil of lubricating viscosity;
a borated dispersant supplying at least 500 ppm boron to said lubricating oil
composition;
an ashless peroxide decomposer present at a treat rate of from about 0.4 to
5.0 wt%;
a metal deactivator wherein the metal deactivator is present at a treat rate
of greater than 0.08
wt%;
wherein said lubricating oil composition contains less than 1000 ppm sulfur,
less than 300
ppm phosphorus and less than 0.25 wt% sulfated ash.
Also provided herein is a method of lubricating an engine with an ultra-low
SAPS
lubricating oil composition comprising:
an oil of lubricating viscosity;
a borated dispersant supplying at least 500 ppm boron to said lubricating oil
composition;
an ashless peroxide decomposer present at a treat rate of from about 0.4 to
5.0 wt%;
a metal deactivator wherein the metal deactivator is present at a treat rate
of greater than 0.08
wt%;
wherein said lubricating oil composition contains less than 1000 ppm sulfur,
less than 300
ppm phosphorus and less than 0.25 wt% sulfated ash.
In one embodiment, the oil soluble ashless peroxide decomposer is as
described U. S. Patent Application No. 20100152079 which is incorporated in
its entirety.
The oil soluble ashless peroxide is a compound according to formula I:
R2 R3
R1 / \N/R4
N
1400
Formula I
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wherein R1 and R2 and R3 and R4 are each independently selected from the group
consisting of alkyl from 1 to 20 carbon atoms, more preferably alkyl from 1 to
10 carbon
atoms and even more preferably lower alkyl from 1 to six carbon atoms. The
alkyl groups
above, can have either a straight chain or a branched chain, which are fully
saturated
hydrocarbon chain; for example, methyl, ethyl, propyl, butyl, pentyl, hexyl,
heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,
heptadecyl,
octadecyl, nonadecyl, and the like, and isomers and mixtures thereof An
example of a
suitable hindered amine that may be used in the present invention is N,N,N',N'-
tetramethyl-
naphthalene-1,8-diamine and sold by Sigma-Aldrich as Proton-spongeTM. The
N,N,N',N'-
tetramethyl-naphthalene-1,8-diamine is a strained molecule due to the close
proximity to the
dimethylamine groups. The free base is destabilized by the steric inhibition
of resonance, van
der Walls repulsions, and lone pair interactions. These strains are typically
relieved by
monoprotonation and formation of an intramolecular hydrogen bond and thus can
effectively
alter the equilibrium constant of the hydroperoxide decomposition reaction.
This imparts a
high basicity relative to normal aliphatic amines or aromatic amines and which
is necessary
to deprotonate a hydroperoxide. Deprotonation of the peroxide would render the
oxygen-
oxygen bond more stable toward decomposition into radicals. The strong
basicity of the
N,N,N',N'-tetramethyl-naphthalene-1,8-diamine can be ascribed to the operation
of several
factors, e.g. the steric inhibition of conjugation in the free base, relief of
nonbonded
repulsions, including a little lone pair/lone pair repulsion, stabilization of
the cation by the
hydrogen bonding, etc. Clearly the N,N,N',N'-tetramethyl-naphthalene-1,8-
diamine structure
is compromise involving several factors including a twist in the naphthalene
ring system,
favorable lone pairhr overlap, lone pair/methyl nonbonded interactions, and
lone pair/lone
pair repulsion.
The compounds of formula I are selected with sufficient alkyl groups to be oil
soluble in the lubricating composition and thus the compound of formula I are
combined with
an oil of lubricating viscosity. The concentration of the compound of formula
I in the
lubricating composition can vary depending upon the requirements, applications
and effect or
degree of synergy desired. In a preferred embodiment of the invention, a
practical N,N,N',N'-
tetraalkyl-naphthalene-1,8-diamine use range in the lubricating composition is
from about 0.4
to 10.0 wt %, and preferably from 0.5 to 3.0 wt%.based on the total weight of
the lubricating
oil composition. The N,N,N',N'-tetraalkyl-naphthalene-1,8-diamine compound of
formula I
can be used as a complete or partial replacement for commercially available
antioxidants
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currently used in lubricant formulations and can be in combination with other
additives
typically found in motor oils and fuels. When used in combination with other
types of
antioxidants or additives used in oil formulations, synergistic and/or
additive performance
effects may also be obtained with respect to improved antioxidancy, antiwear,
frictional and
detergency and high temperature engine deposit properties. Such other
additives can be any
presently known or later-discovered additives used in formulating lubricating
oil
compositions. The lubricating oil additives typically found in lubricating
oils are, for
example, dispersants, detergents, corrosion/rust inhibitors, antioxidants,
anti-wear agents,
anti-foamants, friction modifiers, seal swell agents, emulsifiers, VI
improvers, pour point
depressants, and the like.
Inhibition of free radical-mediated oxidation is one of the most important
reactions in organic substrates and is commonly used in rubbers, polymers and
lubrication
oils; namely, since these chemical products may undergo oxidative damage by
the
autoxidation process. Hydrocarbon oxidation is a three step process which
comprises:
initiation, propagation and termination. Oxidative degradation and the
reaction mechanisms
are dependent upon the specific hydrocarbons, temperatures, operating
conditions, catalysts
such as metals, etc., which more detail can be found in Chapter 4 of Mortier
R.M. et al.,
1992, "Chemistry and Technology of Lubricants Initiation", VCH Publishers,
Inc.;
incorporated herein by reference in its entirety. Initiation involves the
reaction of oxygen or
nitrogen oxides (NO) on a hydrocarbon molecule. Typically, initiation starts
by the
abstraction of hydrocarbon proton. This may result in the formation of
hydrogen peroxide
(HOOH) and radicals such as alkyl radicals (R.) and peroxy radicals (ROO.).
During the
propagation stage, hydroperoxides may decompose, either on their own or in the
presence of
catalysts such as metal ions, to alkoxy radicals (R0.) and peroxy radicals.
These radicals can
react with the hydrocarbons to form a variety of additional radicals and
reactive oxygen
containing compounds such as alcohols, aldehydes, ketones and carboxylic
acids; which
again can further polymerize or continue chain propagation. Termination
results from the self
termination of radicals or by reacting with oxidation inhibitors.
The uncatalyzed oxidation of hydrocarbons at temperatures of up to about 120
C
primarily leads to alkyl-hydroperoxides, dialkylperoxides, alcohols, ketones;
as well as the
products which result from cleavage of dihydroperoxides such as diketones,
keto-aldehydes
hydroxyketones and so forth. At higher temperatures (above 120 C) the
reaction rates are
increased and cleavage of the hydroperoxides plays a more important role.
Since autoxidation
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is a free-radical chain reaction, it therefore, can be inhibited at the
initiation and/or
propagation steps. . Hydroperoxide decomposers convert the hydroperoxides into
non-radical
products and thus prevent the chain propagation reaction. Traditionally
organosulfur and
organophosphorous containing additives have been employed for this purpose
typically
eliminating hydroperoxides via acid catalyzed decomposition or oxygen
transfer. However as
mentioned previously, increased concerns regarding total sulfur and/or
phosphorous content
in finished lubricating oil has led to efforts to reduce or eliminate sulfur
and phosphorous in
lubricant oil formulations. The oil soluble ashless peroxide decomposer
according to formula
I is a potent decomposer which converts hydroperoxides into non-radical
products and thus
prevent the chain propagation reaction.
The oil soluble ashless peroxide decomposer compound according to formula I is
effective by itself when employed in a lubricating oil composition. The oil
soluble ashless
peroxide decomposer compound according to formula I can function as an
antioxidant and
can also be employed in combination with other free radical antioxidants.
In one embodiment sulfur is present in the lubricating oil composition at less
than
1000 ppm, less than 800 ppm, less than 500 ppm, less than 300 ppm, less than
100 ppm less
than 50 ppm, less than 10 ppm, and 0 ppm.
In one embodiment phosphorous is present in the lubricating oil composition at
less
than 300 ppm, less than 200 ppm, less than 100 ppm, less than 50 ppm, less
than 10 ppm, and
0 ppm.
In one embodiment sulfated ash is present in the lubricating oil composition
at less
than0.25 wt%, less than 0.20 wt%, less than 0.15wt%, less than 0.10 wt%, less
than 0.05
wt%, less than 0.01 wt%., and 0 wt.
In one embodiment of the present invention the lubricating oil composition
contains
less than 800 ppm sulfur, less than 200 ppm phosphorous, and less than 0.20
wt% sulfated
ash.
In one embodiment of the present invention the lubricating oil composition
contains
less than 500 ppm sulfur, less than 100 ppm phosphorous, and less than 0.15
wt% sulfated
ash.
In one embodiment of the present invention the lubricating oil composition
contains
less than 300 ppm sulfur, less than 50 ppm phosphorous, and less than 0.10 wt%
sulfated ash.
In one embodiment of the present invention the lubricating oil composition
contains
less than 100 ppm sulfur, 0 ppm phosphorous, and less than 0.05 wt% sulfated
ash.
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In one embodiment of the present invention the lubricating oil composition
contains
less than 50 ppm sulfur, 0 ppm phosphorous, and less than 0.05 wt% sulfated
ash.
In another embodiment, the lubricating oil composition comprises an ashless
metal deactivator. Some non-limiting examples of suitable metal deactivators
include
disalicylidene propylenediamine, triazole derivatives, thiadiazole
derivatives, and
mercaptobenzimidazoles.
The ashless metal deactivator component of the present invention is preferably
an
aromatic triazole or an alkyl-substituted aromatic triazole; for example,
benzotriazole,
tolyltriazole, or mixtures thereof. The most preferred triazole for use is
tolyltriazole. The
metal deactivator is employed at concentrations of about 0.1 ¨ 0.5 wt %;
preferably about 0.1
¨ 0.4 wt. %; preferably about 0.1 ¨ 0.3 wt. %; and more preferably about 0.1 ¨
0.2 wt. %.
Metal deactivators are useful in improving the corrosion protection of copper
and copper
alloys.
In another embodiment, the borated dispersant supplying at least 500 ppm boron
is a
borated succinimide.
Examples of borated ashless dispersants are the borated ashless hydrocarbyl
succinimide dispersants prepared by reacting a hydrocarbyl succinic acid or
anhydride with
an amine. Preferred hydrocarbyl succinic acids or anhydrides are those where
the hydrocarbyl
group is derived from a polymer of a C3 or C4 monoolefin, especially
a
polyisobutylene wherein the polyisobutenyl group has a number average
molecular weight
(Mn) of from 700 to 5,000, more preferably from 900 to 2,500. Such dispersants
generally
have at least 1, preferably 1 to 2, more preferably 1.1 to 1.8, succinic
groups for each
polyisobutenyl group.
Preferred amines for reaction to form the succinimide are polyamines having
from 2
to 60 carbon atoms and from 2 to 12 nitrogen atoms per molecule, and
particularly preferred
are the polyalkyleneamines represented by the formula
NH2(CH2). -(NH(CH2).). -NH2
wherein n is 2 to 3 and m is 0 to 10. Illustrative are ethylene diamine,
diethylene triamine,
triethylene tetramine, tetraethylene pentamine, tetrapropylene pentamine,
pentaethylene
hexamine and the like, as well as the commercially available mixtures of such
polyamines.
Amines including other groups such as hydroxy, alkoxy, amide, nitride and
imidazoline
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groups may also be used, as may polyoxyalkylene polyamines. The amines are
reacted with
the alkenyl succinic acid or anhydride in conventional ratios of about 1:1 to
10:1, preferably
1:1 to 3:1, moles of alkenyl succinic acid or anhydride to polyamine, and
preferably in a ratio
of about 1:1, typically by heating the reactants to from 100° to
250° C.,
preferably 125° to 175° C. for 1 to 10, preferably 2 to 6,
hours.
The boration of alkenyl succinimide dispersants is also well known in the art
as
disclosed in U.S. Pat. Nos. 3 087 936 and 3 254 025. The succinimide may for
example be
treated with a boron compound selected from the group consisting of boron,
boron oxides,
boron halides, boron acids and esters thereof, in an amount to provide from
0.1 atomic
proportion of boron to 10 atomic proportions of boron for each atomic
proportion of nitrogen
in the dispersant.
The borated product will generally contain 0.1 to 2.0, preferably 0.2 to 0.8
weight per
cent boron based upon the total weight of the borated dispersant. Boron is
considered to be
present as dehydrated boric acid polymers attaching at the metaborate salt of
the imide. The
boration reaction is readily carried out adding from 1 to 3 weight per cent
(based on the
weight of dispersant) of said boron compound, preferably boric acid, to the
dispersant as a
slurry in mineral oil and heating with stirring from 135° C. to
165° C. for 1 to 5
hours followed by nitrogen stripping filtration of the product. Alternatively
boric acid may be
added to the hot reaction mixture of succinic acid or anhydride and amine
while removing
water.
In one embodiment, the borated dispersant supplies at least 500 ppm boron to
the
lubricationg oil composition. In one embodiment, the borated dispersant
supplies from 500 to
3000 ppm boron to the lubricationg oil composition. In one embodiment, the
borated
dispersant supplies from 500 to 2500 ppm boron to the lubricationg oil
composition. In one
embodiment, the borated dispersant supplies from 500 to 2000 ppm boron to the
lubricationg
oil composition. In one embodiment, the borated dispersant supplies from 500
to 1500 ppm
boron to the lubricationg oil composition. In one embodiment, the borated
dispersant supplies
from 600 to 1200 ppm boron to the lubricationg oil composition.
THE OIL OF LUBRICATING VISCOSITY
The base oil of lubricating viscosity for use in the lubricating oil
compositions of this
invention 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. %
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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 base 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-butadiene 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
at 100 C of about 2 cSt to about 30 cSt, preferably about 3 cSt to 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-
16, OW-20,
OW-30, OW-40, OW-50, OW-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-
20,
10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30, 15W-40, 20W-40 or 20W-50. Oils
used
as gear oils can have viscosities ranging from about 2 cSt to about 2000 cSt
at 100 C.
Base stocks may be manufactured using a variety of different processes
including, but
not limited to, distillation, solvent refining, hydrogen processing,
oligomerization,
esterification, and rerefining. Rerefined stock shall be substantially free
from materials
introduced through manufacturing, contamination, or previous use. The base oil
of the
lubricating oil compositions of this invention may be any natural or synthetic
lubricating base
oil. Suitable hydrocarbon synthetic oils include, but are not limited to, oils
prepared from the
polymerization of ethylene or from the polymerization of 1-olefins to provide
polymers such
as polyalphaolefin or PAO oils, or from hydrocarbon synthesis procedures using
carbon
monoxide and hydrogen gases such as in a Fischer-Tropsch process. For example,
a suitable
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base oil is one that comprises little, if any, heavy fraction; e.g., little,
if any, lube oil fraction
of viscosity 20 cSt or higher at 100 C.
The base oil may be 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 base stocks produced by
hydrocracking
(rather than solvent extracting) the aromatic and polar components of the
crude. Suitable
base oils include those in all API categories I, II, III, IV and V as defined
in API Publication
1509, 14th Edition, Addendum I, Dec. 1998. Group IV base oils are
polyalphaolefins (PAO).
Group V base oils include all other base oils not included in Group I, II,
III, or IV. Although
Group II, III and IV base oils are preferred for use in this invention, these
base oils may be
prepared by combining one or more of Group I, II, III, IV and V base stocks or
base oils.
Useful 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.
Useful 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 useful 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 useful 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 useful synthetic lubricating oils include, but are not
limited to,
alkylene oxide polymers, i.e., homopolymers, interpolymers, and derivatives
thereof where
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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 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 useful 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-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.
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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.
LUBRICATING OIL ADDITIVES
The lubricating oil compositions of the present invention may also contain
other
conventional additives for imparting auxiliary functions to give a finished
lubricating oil
composition in which these additives are dispersed or dissolved. For example,
the lubricating
oil compositions can be blended with antioxidants, anti-wear agents, ashless
dispersants,
detergents, rust inhibitors, dehazing agents, demulsifying agents, metal
deactivating agents,
friction modifiers, pour point depressants, antifoaming agents, co-solvents,
package
compatibilisers, corrosion-inhibitors, 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 invention by the usual blending procedures.
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Examples of antioxidants include, but are not limited to, aminic types, e.g.,
diphenylamine, phenyl-alpha-napthyl-amine, N,N-di(alkylphenyl) amines; and
alkylated
phenylene-diamines; phenolics such as, for example, BHT, sterically hindered
alkyl phenols
such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-
buty1-4-(2-octy1-3-
propanoic) phenol; and mixtures thereof The antioxidants of the present
invention can be
aminic, phenolic, or mixtures thereof
Examples of antiwear agents include, but are not limited to, zinc
dialkyldithiophosphates and zinc diaryldithiophosphates, e.g., those described
in an article by
Born et al. entitled "Relationship between Chemical Structure and
Effectiveness of Some
Metallic Dialkyl- and Diaryl-dithiophosphates in Different Lubricated
Mechanisms",
appearing in Lubrication Science 4-2 January 1992, see for example pages 97-
100; aryl
phosphates and phosphites, sulfur-containing esters, phosphosulfur compounds,
metal or ash-
free dithiocarbamates, xanthates, alkyl sulfides and the like and mixtures
thereof
Representative examples of ashless dispersants include, but are not limited
to, amines,
alcohols, amides, or ester polar moieties attached to the polymer backbones
via bridging
groups. An ashless dispersant of the present invention may be, for example,
selected from oil
soluble salts, esters, amino-esters, amides, imides, and oxazolines of long
chain hydrocarbon
substituted mono and dicarboxylic acids or their anhydrides; thiocarboxylate
derivatives of
long chain hydrocarbons, long chain aliphatic hydrocarbons having a polyamine
attached
directly thereto; and Mannich condensation products formed by condensing a
long chain
substituted phenol with formaldehyde and polyalkylene polyamine.
Carboxylic dispersants are reaction products of carboxylic acylating agents
(acids,
anhydrides, esters, etc.) comprising at least about 34 and preferably at least
about 54 carbon
atoms with nitrogen containing compounds (such as amines), organic hydroxy
compounds
(such as aliphatic compounds including monohydric and polyhydric alcohols, or
aromatic
compounds including phenols and naphthols), and/or basic inorganic materials.
These
reaction products include imides, amides, and esters.
Succinimide dispersants are a type of carboxylic dispersant. They are produced
by
reacting hydrocarbyl-substituted succinic acylating agent with organic hydroxy
compounds,
or with amines comprising at least one hydrogen atom attached to a nitrogen
atom, or with a
mixture of the hydroxy compounds and amines. The term "succinic acylating
agent" refers to
a hydrocarbon-substituted succinic acid or a succinic acid-producing compound,
the latter
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encompasses the acid itself Such materials typically include hydrocarbyl-
substituted
succinic acids, anhydrides, esters (including half esters) and halides.
Succinic-based dispersants have a wide variety of chemical structures. One
class of
succinic-based dispersants may be represented by the formula:
H H
\
R'-- C- C ,C- C - R1
1 \
N4 R2- N111- R2- N 1
H-C - C, x
I
I µ ,C - C - H
H 0 0 H
wherein each R1 is independently a hydrocarbyl group, such as a polyolefin-
derived group.
Typically the hydrocarbyl group is an alkyl group, such as a polyisobutyl
group.
Alternatively expressed, the R1 groups can contain about 40 to about 500
carbon atoms, and
these atoms may be present in aliphatic forms. R2 is an alkylene group,
commonly an
ethylene (C2H4) group. Examples of succinimide dispersants include those
described in, for
example, U.S. Patent Nos. 3,172,892, 4,234,435 and 6,165,235.
The polyalkenes from which the substituent groups are derived are typically
homopolymers and interpolymers of polymerizable olefin monomers of 2 to about
16 carbon
atoms, and usually 2 to 6 carbon atoms. The amines which are reacted with the
succinic
acylating agents to form the carboxylic dispersant composition can be
monoamines or
polyamines.
Succinimide dispersants are referred to as such since they normally contain
nitrogen
largely in the form of imide functionality, although the amide functionality
may be in the
form of amine salts, amides, imidazolines as well as mixtures thereof To
prepare a
succinimide dispersant, one or more succinic acid-producing compounds and one
or more
amines are heated and typically water is removed, optionally in the presence
of a
substantially inert organic liquid solvent/diluent. The reaction temperature
can range from
about 80 C up to the decomposition temperature of the mixture or the product,
which
typically falls between about 100 C to about 300 C. Additional details and
examples of
procedures for preparing the succinimide dispersants of the present invention
include those
described in, for example, U.S. Patent Nos. 3,172,892, 3,219,666, 3,272,746,
4,234,435,
6,165,235 and 6,440,905.
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Suitable ashless dispersants may also include amine dispersants, which are
reaction
products of relatively high molecular weight aliphatic halides and amines,
preferably
polyalkylene polyamines. Examples of such amine dispersants include those
described in, for
example, U.S. Patent Nos. 3,275,554, 3,438,757, 3,454,555 and 3,565,804.
Suitable ashless dispersants may further include "Mannich dispersants," which
are
reaction products of alkyl phenols in which the alkyl group contains at least
about 30 carbon
atoms with aldehydes (especially formaldehyde) and amines (especially
polyalkylene
polyamines). Examples of such dispersants include those described in, for
example, U.S.
Patent Nos. 3,036,003, 3,586,629. 3,591,598 and 3,980,569.
Suitable ashless dispersants may also be post-treated ashless dispersants such
as post-
treated succinimides, e.g., post-treatment processes involving borate or
ethylene carbonate as
disclosed in, for example, U.S. Patent Nos. 4,612,132 and 4,746,446; and the
like as well as
other post-treatment processes. The carbonate-treated alkenyl succinimide is a
polybutene
succinimide derived from polybutenes having a molecular weight of about 450 to
about 3000,
preferably from about 900 to about 2500, more preferably from about 1300 to
about 2400,
and most preferably from about 2000 to about 2400, as well as mixtures of
these molecular
weights. Preferably, it is prepared by reacting, under reactive conditions, a
mixture of a
polybutene succinic acid derivative, an unsaturated acidic reagent copolymer
of an
unsaturated acidic reagent and an olefin, and a polyamine, such as disclosed
in U.S. Patent
No. 5,716,912, the contents of which are incorporated herein by reference.
An example of a suitable ashless dispersant is a borated dispersant. Borated
dispersants may be formed by boronating (borating) an ashless dispersant
having basic
nitrogen and/or at least one hydroxyl group in the molecule, such as a
succinimide dispersant,
succinamide dispersant, succinic ester dispersant, succinic ester-amide
dispersant, Mannich
base dispersant, or hydrocarbyl amine or polyamine dispersant. Methods that
can be used for
boronating the various types of ashless dispersants described above are
described, for
example, in U.S. Pat. Nos. 4,455,243 and 4,652,387.
Suitable ashless dispersants may also be polymeric, which are interpolymers of
oil-
solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high
molecular
weight olefins with monomers containing polar substitutes. Examples of
polymeric
dispersants include those described in, for example, U.S. Patent Nos.
3,329,658; 3,449,250
and 3,666,730.
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In one preferred embodiment of the present invention, an ashless dispersant
for use in
the lubricating oil composition is a bis-succinimide derived from a
polyisobutenyl group
having a number average molecular weight of about 700 to about 2300. The
dispersant(s) for
use in the lubricating oil compositions of the present invention are
preferably non-polymeric
(e g., are mono- or bis-succinimides).
Generally, the one or more ashless dispersants are present in the lubricating
oil
composition in an amount ranging from about 0.01 wt. % to about 20 wt. %,
based on the
total weight of the lubricating oil composition.
Representative examples of metal detergents include sulphonates,
alkylphenates,
sulfurized alkyl phenates, carboxylates, salicylates, phosphonates, and
phosphinates.
Commercial products are generally referred to as neutral or overbased.
Overbased metal
detergents are generally produced by carbonating a mixture of hydrocarbons,
detergent acid,
for example: sulfonic acid, alkylphenol, carboxylate 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.
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. 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, and would typically have a total
base number or
TBN (as can be measured by ASTM D2896) of from 0 to about 80. 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). The resulting overbased
detergent
comprises neutralized detergent as the outer layer of a metal base (e.g.,
carbonate) micelle.
Such overbased detergents may have a TBN of about 150 or greater, and
typically will have a
TBN of from about 250 to about 450 or more.
Detergents that may be used include oil-soluble neutral and overbased
sulfonates,
phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates
and other oil-
soluble carboxylates of a metal, particularly the alkali or alkaline earth
metals, e.g., barium,
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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. Particularly convenient
metal
detergents are neutral and overbased calcium sulfonates having TBN of from
about 20 to
about 450, neutral and overbased calcium phenates and sulfurized phenates
having TBN of
from about 50 to about 450 and neutral and overbased magnesium or calcium
salicylates
having a TBN of from about 20 to about 450. Combinations of detergents,
whether
overbased or neutral or both, may be used.
In one embodiment, the detergent can be one or more alkali or alkaline earth
metal
salts of an alkyl-substituted hydroxyaromatic carboxylic acid. Suitable
hydroxyaromatic
compounds include mononuclear monohydroxy and polyhydroxy aromatic
hydrocarbons
having 1 to 4, and preferably 1 to 3, hydroxyl groups. Suitable
hydroxyaromatic compounds
include phenol, catechol, resorcinol, hydroquinone, pyrogallol, cresol, and
the like. The
preferred hydroxyaromatic compound is phenol.
The alkyl substituted moiety of the alkali or alkaline earth metal salt of an
alkyl-
substituted hydroxyaromatic carboxylic acid is derived from an alpha olefin
having from
about 10 to about 80 carbon atoms. The olefins employed may be linear,
isomerized linear,
branched or partially branched linear. The olefin may be a mixture of linear
olefins, a
mixture of isomerized linear olefins, a mixture of branched olefins, a mixture
of partially
branched linear or a mixture of any of the foregoing.
In one embodiment, the mixture of linear olefins that may be used is a mixture
of
normal alpha olefins selected from olefins having from about 12 to about 30
carbon atoms
per molecule. In one embodiment, the normal alpha olefins are isomerized using
at least one
of a solid or liquid catalyst.
In another embodiment, the olefins are a branched olefinic propylene oligomer
or
mixture thereof having from about 20 to about 80 carbon atoms, i.e., branched
chain olefins
derived from the polymerization of propylene. The olefins may also be
substituted with other
functional groups, such as hydroxy groups, carboxylic acid groups,
heteroatoms, and the like.
In one embodiment, the branched olefinic propylene oligomer or mixtures
thereof have from
about 20 to about 60 carbon atoms. In one embodiment, the branched olefinic
propylene
oligomer or mixtures thereof have from about 20 to about 40 carbon atoms.
In one embodiment, at least about 75 mole% (e.g., at least about 80 mole%, at
least
about 85 mole%, at least about 90 mole%, at least about 95 mole%, or at least
about 99
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mole%) of the alkyl groups contained within the alkali or alkaline earth metal
salt of an alkyl-
substituted hydroxyaromatic carboxylic acid such as the alkyl groups of an
alkaline earth
metal salt of an alkyl-substituted hydroxybenzoic acid detergent are a C20 or
higher. In
another embodiment, the alkali or alkaline earth metal salt of an alkyl-
substituted
hydroxyaromatic carboxylic acid is an alkali or alkaline earth metal salt of
an alkyl-
substituted hydroxybenzoic acid that is derived from an alkyl-substituted
hydroxybenzoic
acid in which the alkyl groups are the residue of normal alpha-olefins
containing at least 75
mole% C20 or higher normal alpha-olefins.
In another embodiment, at least about 50 mole % (e.g., at least about 60 mole
%, at
least about 70 mole %, at least about 80 mole %, at least about 85 mole %, at
least about 90
mole %, at least about 95 mole %, or at least about 99 mole %) of the alkyl
groups contained
within the alkali or alkaline earth metal salt of an alkyl-substituted
hydroxyaromatic
carboxylic acid such as the alkyl groups of an alkali or alkaline earth metal
salt of an alkyl-
substituted hydroxybenzoic acid are about C14 to about C18.
The resulting alkali or alkaline earth metal salt of an alkyl-substituted
hydroxyaromatic carboxylic acid will be a mixture of ortho and para isomers.
In one
embodiment, the product will contain about 1 to 99% ortho isomer and 99 to 1%
para isomer.
In another embodiment, the product will contain about 5 to 70% ortho and 95 to
30% para
isomer.
The alkali or alkaline earth metal salts of an alkyl-substituted
hydroxyaromatic
carboxylic acid can be neutral or overbased. Generally, an overbased alkali or
alkaline earth
metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is one in
which the BN of
the alkali or alkaline earth metal salts of an alkyl-substituted
hydroxyaromatic carboxylic acid
has been increased by a process such as the addition of a base source (e.g.,
lime) and an
acidic overbasing compound (e.g., carbon dioxide).
Overbased salts may be low overbased, e.g., an overbased salt having a BN
below
about 100. In one embodiment, the BN of a low overbased salt may be from about
5 to about
50. In another embodiment, the BN of a low overbased salt may be from about 10
to about
30. In yet another embodiment, the BN of a low overbased salt may be from
about 15 to
about 20.
Overbased detergents may be medium overbased, e.g., an overbased salt having a
BN
from about 100 to about 250. In one embodiment, the BN of a medium overbased
salt may
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be from about 100 to about 200. In another embodiment, the BN of a medium
overbased salt
may be from about 125 to about 175.
Overbased detergents may be high overbased, e.g., an overbased salt having a
BN
above about 250. In one embodiment, the BN of a high overbased salt may be
from about
250 to about 450.
Sulfonates may be prepared from sulfonic acids which are typically obtained by
the
sulfonation of alkyl substituted aromatic hydrocarbons such as those obtained
from the
fractionation of petroleum or by the alkylation of aromatic hydrocarbons.
Examples included
those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl
or their halogen
derivatives. The alkylation may be carried out in the presence of a catalyst
with alkylating
agents having from about 3 to more than 70 carbon atoms. The alkaryl
sulfonates usually
contain from about 9 to about 80 or more carbon atoms, preferably from about
16 to about 60
carbon atoms per alkyl substituted aromatic moiety.
The oil soluble sulfonates or alkaryl sulfonic acids may be neutralized with
oxides,
hydroxides, alkoxides, carbonates, carboxylate, sulfides, hydrosulfides,
nitrates, borates and
ethers of the metal. The amount of metal compound is chosen having regard to
the desired
TBN of the final product but typically ranges from about 100 to about 220 wt.
% (preferably
at least about 125 wt. %) of that stoichiometrically required.
Metal salts of phenols and sulfurized phenols are prepared by reaction with an
appropriate metal compound such as an oxide or hydroxide and neutral or
overbased products
may be obtained by methods well known in the art. Sulfurized phenols may be
prepared by
reacting a phenol with sulfur or a sulfur containing compound such as hydrogen
sulfide,
sulfur monohalide or sulfur dihalide, to form products which are generally
mixtures of
compounds in which 2 or more phenols are bridged by sulfur containing bridges.
Generally, the one or more detergents are present in the lubricating oil
composition in
an amount ranging from about 0.01 wt. % to about 10 wt. %, based on the total
weight of the
lubricating oil composition.
Examples of rust inhibitors include, but are not limited to, nonionic
polyoxyalkylene
agents, e.g., polyoxyethylene lauryl ether, polyoxyethylene higher alcohol
ether,
polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether,
polyoxyethylene
octyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitol
monostearate,
polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate;
stearic acid and
other fatty acids; dicarboxylic acids; metal soaps; fatty acid amine salts;
metal salts of heavy
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sulfonic acid; partial carboxylic acid ester of polyhydric alcohol; phosphoric
esters; (short-
chain) alkenyl succinic acids; partial esters thereof and nitrogen-containing
derivatives
thereof; synthetic alkarylsulfonates, e.g., metal dinonylnaphthalene
sulfonates; and the like
and mixtures thereof
Examples of friction modifiers include, but are not limited to, alkoxylated
fatty
amines; borated fatty epoxides; fatty phosphites, fatty 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 C25, preferably a C6 to C24, and most preferably a C6 to
C20, fatty acid ester
and a nitrogen-containing compound selected from the group consisting of
ammonia, and an
alkanolamine and the like and mixtures thereof
Examples of antifoaming agents include, but are not limited to, polymers of
alkyl
methacrylate; polymers of dimethylsilicone and the like and mixtures thereof
Examples of a pour point depressant include, but are not limited to,
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 one embodiment, a pour point
depressant
comprises an ethylene-vinyl acetate copolymer, a condensate of chlorinated
paraffin and
phenol, polyalkyl styrene and the like and combinations thereof The amount of
the pour
point depressant may vary from about 0.01 wt. % to about 10 wt. %.
Examples of a demulsifier include, but are not limited to, 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 the like and combinations thereof
The amount of
the demulsifier may vary from about 0.01 wt. % to about 10 wt. %.
Examples of a corrosion inhibitor include, but are not limited to, half esters
or amides
of dodecylsuccinic acid, phosphate esters, thiophosphates, alkyl imidazolines,
sarcosines and
the like and combinations thereof The amount of the corrosion inhibitor may
vary from
about 0.01 wt. % to about 5 wt. %.
The corrosion inhibitor component can be a non-polycarboxylate moiety
containing
thiadiazole. Preferably, the thiadiazole comprises at least one of 2,5-
dimercapto-1,3,4-
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thiadiazo le ; 2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles; 2 -merc apto-5
-
hydrocarbyldithio-1,3 ,4-thiadiazoles ; 2,5-bis(hydrocarbylthio and 2,5-
bis(hydrocarbyldithio)-
1,3,4-thiadiazoles. The more preferred compounds are the 1,3,4-thiadiazoles,
especially the
2-hydrocarbyldithio-5 -mercapto-1,3 ,4-dithiadiazo les and the 2,5-
bis(hydrocarbyldithio)-
1,3,4-thiadiazoles, a number of which are available as articles of commerce.
Most preferably,
a non polycarboxylate containing thiadiazole containing about 4.0 wt% 2,5-
dimercapto-1,3,4-
thiadiazole, which may be either Ethyl Corporation's Hitec0 4313 or Lubrizol
Corporation's
Lubrizol 5955A, is used. Hitec0 4313 may be obtained from Ethyl Corporation,
Richmond, Virginia and Lubrizol 5955A may be obtained from Lubrizol
Corporation,
Wycliffe, Ohio.
Examples of an extreme pressure agent include, but are not limited to,
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 the like and combinations thereof The amount of the extreme
pressure agent may
vary from about 0.01 wt. % to about 5 wt. %.
Each of the foregoing additives, when used, is used at a functionally
effective amount
to impart the desired properties to the lubricant. Thus, for example, if an
additive is a friction
modifier, a functionally effective amount of this friction modifier would be
an amount
sufficient to impart the desired friction modifying characteristics to the
lubricant. Generally,
the concentration of each of these additives, when used, may range, unless
otherwise
specified, from about 0.001% to about 20% by weight, and in one embodiment
about 0.01%
to about 10% by weight based on the total weight of the lubricating oil
composition.
In another embodiment of the invention, the lubricating oil additives of the
present
invention may be provided as an additive package or concentrate in which the
additives are
incorporated into a substantially inert, normally liquid organic diluent such
as, for example,
mineral oil, naphtha, benzene, toluene or xylene to form an additive
concentrate. These
concentrates usually contain from about 20% to about 80% by weight of such
diluent.
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Typically, a neutral oil having a viscosity of about 4 to about 8.5 cSt at 100
C and preferably
about 4 to about 6 cSt at 100 C will be used as the diluent, though synthetic
oils, as well as
other organic liquids which are compatible with the additives and finished
lubricating oil can
also be used.
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 performance is exemplified by a standard GF-5 oil. This oil has
SAPS levels near the mandated limit: sulfur of 0.2 wt%, phosphorus of 0.075
wt% and
sulfated ash of 1.1 wt%.
When all additives contributing to SAPS levels were removed (Ultra-Low SAPS
oil
A) the performance on the High Temperature Corrosion Bench Test (HTCBT), Ball
Rust Test
(BRT) and Thermo-oxidation engine oil simulation test at moderately high
temperature
(TEOST MHT-4) dropped to unacceptable levels (Table 1).
Table 1
Oil Baseline GF5 oil Ultra-Low SAPS oil A
HTCBT (Cu/Pb) 10/32 13/338
BRT 124 25
TEOST MHT-4 44.7 160.3
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Comparative examples Ultra-Low SAPS oils A to K and inventive Example 1 are
shown in Table 2. In Table 2, the unit for S (Sulfur), and P (Phosphorous) is
ppm, and for
Ash (Sulfated Ash) is wt% in the fully formulated lubricating oil.
The performance of each oil was evaluated using:
(a) The High Temperature Corrosion Bench Test (HTCBT) ASTM D6594 (Version 08).
Passing levels for the HTCBT are: Copper are less than 20 ppm; and Lead less
than
120 ppm.
(b) Ball Rust Test (BRT) ASTM D6557 (Version 10a). Passing for the BRT is
greater
than 100 Average Grey Value (AVG).
(c) Thermo-oxidation engine oil simulation test at moderately high temperature
(TEOST
MHT-4) ASTM D7097 (Version 09). Passing for the TEOST MHT-4 is less than 45
mg.
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Table 2
Exa mples> A B C D E F G HI J K 1
Borated Dispersant,
wt.% 6.5 6.5 6.5 13
13
Boron in Lubricating
Oil Composition, ppm 410 410 410
820 820
Dispersant A, wt.% 2 6.5 6.5
Dispersant B, wt.% 6.5 13 6.5
13
Aminic AO, wt.% 0.4 1.5 1 1.5 0.4 0.4 0.4 0.4
0.4 0.4 0.4 0.4
Phenolic AO, wt.% 0.5 3 0.5 3 3 3 3 3 3 3
3
Decomposer, wt.% 1 1 0.6 0.3 0.3 0.6 0.6
0.3 0.3 0.6
Metal Deactivator, 0.0 0.0 0.0
wt.% 0.2
0.2 5 0.2 0.05 0.2 5 5 0.2 0.2
HTCBT Cu 13 2 29 4 9 4 28 4 16 6 8
12
83 177. 74 85
HTCBT PB 322 2 338 5 88 216 189 3 4
694 999 81
11
BRT
25 26 71 127 103 38 111 34 9 22 64 117
101. 70. 46. 52. 38.
TEOST M HT-4 160.3 26 2 58.5 56 74.8 41.6 9 8
7 2 36.5
26 26 24
S (Group II Baseoil) 291 6 275 270 268 268 250
7 9 269 249 248
P (Group II Baseoil) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0
Ash Group II Baseoil) 0.0 0.0 0.0 300 300 300 800 0.0
0.0 0.0 0.0 800
S (Group III Baseoil) 4.9 4.4 4.6 4.5 4.5 4.5 4.2
4.5 4.1 4.5 4.1 4.1
P (Group III Baseoil) 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
Ash Group III Baseoil) 0.0 0.0 0.0 300 300 300 800 0.0
0.0 0.0 0.0 800
In Table 2, the unit for S (Sulfur), and P (Phosphorous) is ppm and for Ash
(Sulfated
Ash) is wt% in the lubricating oil composition.
The components in Table 2 are described below:
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Borated dispersant: An oil concentrate of borated succinimide derived from
1300 MW Poly
Iso-Butylene Succinic Anhydride (PIBSA) and heavy polyamine (HPA).
Dispersant A: An oil concentrate of ethylene carbonate-treated succinimide
derived from
2300 MW PIBSA and heavy polyamine (HPA).
Dispersant B: A Succinimide synthesized from 2300 MW PIBSA and heavy polyamine
(HPA).
Decomposer: is the Ashless Peroxide Decomposer according to Formula 1 in the
present
application.
Table 3
TEST Cu Pb BRT TEOST
Comparative Example A Pass Fail Fail Fail
Comparative Example B Pass Fail Fail Pass
Comparative Example C Fail Fail Fail Fail
Comparative Example D Pass Fail Pass Fail
Comparative Example E Pass Pass Pass Fail
Comparative Example F Pass Fail Fail Fail
Comparative Example G Fail Fail Pass Pass
Comparative Example H Pass Fail Fail Fail
Comparative Example l Pass Fail Pass Fail
Comparative Example J Pass Fail Fail Fail
Comparative Example K Pass Fail Fail Pass
Inventive Example 1 Pass Pass Pass Pass
Table 3 is a Pass / Fail summary of Comparative Examples A to K and Inventive
Example 1 in the HT CBT (Cu, Pb), BRT and TEOST tests.
28
