Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
Alkali Metal Salts to Minimize Turbo Sludge
BACKGROUND OF THE INVENTION
10001.1 The disclosed technology relates to reduction of turbo sludge
formation in the course of lubricating a turbo-charged, sump-lubricated
internal
combustion engine which is susceptible to contamination of lubricant with
liquid the!.
[0002] Modern engine lubricants are formulated to provide performance
in a
number of important areas. One of these areas is the minimization of sludge
and
related deposits in the engine. Problems with excessive sludge formation have
historically been associated with extensive stop-and-go driving particularly
during cold, damp weather conditions. Sludge formation in the crankcase and
oils passages of an engine can seriously limit the ability of the crankcase
oil to
lubricate the engine effectively. To address this problem, most engine
lubricants contain dispersants such as succinimide dispersants of various
types,
and these have usually been quite effective at retaining sludge-forming
materials
in solution or dispersion. An example of the use of a succinimide dispersant
to
address problems of sludge is reported in U.S. patent 6,770,605, Stachew et
al.,
August 3, 2004.
[0003] Recently, however, new sludge problems have appeared. Sludge and
deposits have been observed, especially in turbo-charged engines, and in
particular turbo-charged gasoline (spark-ignited) engines, for instance, on
the
cylinder head and in the lubricant sump. This heavy sludge and deposit
formation may lead to bearing oil starvation and blockage of the oil feed
filter
and, in extreme eases, to catastrophic engine failure, These problems seem
more severe in engines that are fueled with certain grades of gasoline. This
"turbo-sludge" problem has been resistant to solution by the customary use of
dispersants.
[0004j Lubricants for internal combustion engines, including those
equipped
with turbochargers, are known. For example, U.S. Patent 6,458,750, Dardin et
al., October 1, 2002, discloses an engine oil composition with reduced deposit-
formation tendency, including an alkyl alkoxylate. Deposit formation is
evaluated in terms of, among other things, turbo deposition in heavy diesel.
engines. U.S. Patent 6,586,276, Nakanishi et al., July I, 2003, discloses a
heat
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resistant and oxidation resistant lubricating oil composition which includes a
polyphenylthioether as an antioxidant or a lubricating base oil component. A
heat resistant base oil may be used. The lubricant is suitable for automobile
engines such as turbo engines, and jet engines and gas turbines operated at
high
speed and high temperature. U.S. Patent
Application Publication US
2003/0162674, Scott, August 28, 2003, discloses a heavy duty diesel engine
lubricating oil comprising a Group HI basestock, a detergent composition, and
one or more other additives. The lubricant is said to minimize the loss of
efficiency of a turbo-charger included in the engine assembly.
[0005] It is believed that the prior art does not recognize the unique
difficulties associated with turbo sludge nor does it provide a way to
minimize
the turbo sludge.
SUMMARY OF THE INVENTION
100061 The
disclosed technology provides a method for lubricating a turbo-
-- charged, sump-lubricated internal combustion engine which is susceptible to
contamination of lubricant with liquid fuel (and in some embodiments in which
the lubricant is in fact contaminated with fuel), comprising providing said
engine with a lubricant which contains an. amount of an oil-soluble alkali
metal
salt effective to reduce the deterioration of said lubricant.
DETAILED DESCRIPTION OF THE INVENTION
[0007]
Various features and embodiments will be described below by way of
non-limiting illustration.
[0008] The
present inventors have analyzed turbo sludge and determined that
chemically it is not obviously different from ordinary engine sludge. Both are
-- substantially carbonaceous or hydrocarbonaceous materials which may
contain.
organic acids. However, turbo sludge appears to be more brittle than ordinary
sludge and may consist of discrete particles of sediment of millimeter and sub
millimeter size (e.g, 0.1 to 1 mm).
[0009] The
turbo sludge formation appears to be more prominent or more
-- often formed when certain gasoline grades are used as fuels. Gasolines in
general are hydrocarbon distillate fuels in the gasoline range, such as those
meeting the specifications given in American Society for Testing and Materials
Specification D-439, "Standard Specification for Automotive Gasoline."
Gasolines may generally have a boiling range of 30 to 215 C or, more
precisely,
-- as defined by ASTM specification D86-00 for a mixture of hydrocarbons
having
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a distillation range from about 60 C at the 10% distillation point to about
205 C
at the 90% distillation point. Gasoline is typically composed of a mixture of
various types of hydrocarbons including aromatics, olefins, paraffins,
isoparaffins, naphthenes and occasionally diolefins. Liquid fuel compositions
comprising non-hydrocarbonaceous materials such as alcohols, ethers, and
organo-nitro compounds (e.g., methanol, ethanol, diethyl ether, methyl ethyl
ether, methyl t-butyl ether, nitrornethane) may also benefit from the present
invention. The gasoline may have a sulphur content of less than or equal to 50
parts per million by weight or alternatively less than 30 or 20 or 15 or 10
parts
per million, and a lower :level of 0 or 0.1 or 0,5 or 1 or 2 parts per
million. The
gasoline may have any of the conventional octane ratings and may contain the
conventional additives used for treatment of gasoline, e.g., solvents, anti-
knock
compounds, detergents, dispersants, fluidizers, and scavengers. Ciasolines may
also include materials prepared by a Fischer-Tropsch gas to liquid process and
emulsified water-blended fuel compositions as described, for instance, in U.S.
Patent 6,858,046, Daly et al., February 2, 2005.
100101 The
present inventors have determined that the problem of turbo
sludge tends to be more severe when fuels are used which contain a relatively
higher percentage of high boiling material and which contain a relatively
large
fraction of cyclic materials such as aromatics, in particular, relatively high
boiling (>150 C) cyclic materials such as aromatics. In some such severe
fuels,
there may also be a relatively high percentage of naphthenic fraction (also
called
cycloparaffins). It will be recognized, however, that there may be other
parameters as well in determining the sludge-forming tendency of a fuel.
Focusing on the boiling range, for instance, a "clean" fuel (one which
produces
little or no turbo sludge) may have a boiling range such that 10 percent or
even
less of the fuel boils above 150 C at atmospheric pressure. On the other hand,
in a "dirty" fuel, 30 percent or more (or greater than 10 percent, 15 percent,
20
percent, or 25 percent) may boil above 150 C. The high boiling fraction
appears to comprise aromatic or naphthenic components, including aromatic
materials having one or more hydrocarbyl substituents totalling 3 or more
carbon atoms, or alternatively polycyclic paraffins such as "decalin"
(decahydronapthalene) and other closely related dicyclic species. An
appreciable fraction (e.g., 4-15%, 5-12%, or 6-10%) of such fuels may boil in
the range of 180 to 200 C or 184 to 196 C. Thus a "clean" fuel may contain 5
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percent or less of aromatics (e.g., 3% or less or 1% or less, such as down to
0.1
or 0.5%) and a "dirty" fuel may contain larger amounts of aromatics, e.g.,
greater than 5 percent, 10 percent, 12 percent, or 14 percent. An upper amount
of aromatic component or naphthenes in such a fuel is not rigidly defined but
may be, in certain embodiments, up to 30 percent or 20 percent by weight.
These values, of course, may not always be definitive if other factors may be
important for a given fuel, such as sulfur content, aromatic content, olefins
content, ratio of monocyclic to dicyclic naphthenes, or isoparaffin content.
EOM While not wishing to be bound by any theory, the inventors
speculate
that cyclic (or other deleterious) materials as described above may find their
way into the lubricant system as a contaminant and may be retained there for
comparatively longer times because of their higher boiling temperatures,
compared to other portions of the fuel contaminant. These materials and the
lubricant in which they are contained, will he, during the course of
lubrication,
be exposed to the high temperatures of a turbocharger, which are typically
higher than temperature encountered during lubrication of a conventional
engine, e.g., at least 180 C or at least 200 C or at least 250 C or even at
least
300 C. Under these conditions, the lubricant mixture may deteriorate, leading
to the formation of the turbo sludge. Whether the naphthenic component of the
gasoline itself (or its decomposition product) becomes a major component of
the
turbo sludge, or whether the naphthenic component catalyzes formation of turbo
sludge from components of the lubricant itself, or some combination thereof,
is
not known with certainty. However, it is proposed that the turbo sludge or
precursors thereof may be formed initially within the turbocharger but then be
washed away by additional lubricant and thereby accumulate in other parts of
the engine such as the sump.
100121 The problem of turbo sludge is reduced or eliminated by use of a
lubricant that comprises an oil of lubricating viscosity, an effective amount
of
an oil-soluble alkali metal salt and, typically, other additives. Thus, the
present
technology includes the use of the alkali metal salt as described herein in
such a
lubricant to reduce or eliminate turbo sludge.
100131 The oil of lubricating viscosity, or base oil, used in the
inventive
lubricating oil composition may be selected from any of the base oils in
Groups
I-V as specified in the American Petroleum Institute (API) Base Oil
Interchangeability Guidelines, The five base oil groups are as follows:
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Base Oil Viscosity
Category Sulfur ( /0) aturates(%) Index
Group I >0,03 and/or <90 80 to 120
Group II s'0.03 and ?_90 80 to 120
Group Ill 52:0.03 and -290 ;21120
Group IV All polyalphaolefins (PA.0s)
Group V All others not included in Groups 1, II, III or IV
Groups I, II and III are mineral oil base stocks. The oil of lubricating
viscosity,
then, can include natural or synthetic lubricating oils and mixtures thereof.
Mixture of mineral oil and synthetic oils, particularly polyalphaolefin oils
and
polyester oils, are often used. In certain embodiments of the present
invention,
the oil used to form the final lubricant composition (including contributions
from oil used as diluent oil for additives) may contain at most 60 percent by
weight Group I oil, or at most 40 or 20 or 10 %. In such cases, a
complementary amount of the oil may be group II, HI, IV, or V.
[0014] Natural oils include animal oils and vegetable oils (e.g. castor
oil,
lard oil and other vegetable acid esters) as well as mineral lubricating oils
such
as liquid petroleum oils and solvent-treated or acid treated mineral
lubricating
oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types.
Hydrotreated or hydrocracked oils are included within the scope of useful oils
of
lubricating viscosity.
[00151 Oils of lubricating viscosity derived from coal or shale are
also
2.5 useful. Synthetic lubricating oils include hydrocarbon oils and
halosubstituted
hydrocarbon oils such as polymerized and interpolymerized olefins and mixtures
thereof, alkylbenzenes, yphenyl, (e.g., biphenyls, terphenyls, and
alkylated
polyphenyls), alkylated diphenyi ethers and alkylated diphenyl sulfides and
their
derivatives, analogs and homologues thereof. .Alkylene oxide polymers and
interpolymers and derivatives thereof, and those where terminal hydroxyl
groups have been modified by, for example, esterification or etherification,
constitute other classes of known synthetic lubricating oils that can be used.
Another suitable class of synthetic lubricating oils that can be used
comprises
the esters of dicarboxylic acids and those made from C5 to C12 monocarboxylic
acids and polyols or polyol ethers.
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[0016] Other synthetic lubricating oils include liquid esters of
phosphorus-
containing acids, polymeric tetrahydrofurans, silicon-based oils such as the
poly-
alkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils, and silicate
oils.
[0017] Hydrotreated naphthenic oils are also known and can be used.
Synthetic oils may be used such as those produced by Fischer-Tropsch reactions
and typically may be hydroisomerised Fischer-Tropsch hydrocarbons or waxes.
in one embodiment oils may be prepared by a Fischer-Tropsch gas-to-liquid
synthetic procedure as well as other gas-to-liquid oils.
[0018] Unrefined, refined and rerefined oils, either natural or
synthetic (as
well as mixtures of two or more of any of these) of the type disclosed
hereinabove can used in the compositions of the present invention. Unrefined
oils are those obtained directly from a natural or synthetic source without
further purification 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. Rerefined oils are obtained by processes
similar to those used to obtain refined oils applied to refined oils which
have
been already used in service. Such rerefined oils often are additionally
processed by techniques directed to removal of spent additives and oil
breakdown products.
[0019] The amount of the base oil in the lubricant composition will
typically
be the amount of the composition remaining after the other named components
and additives are accounted for. The amounts reported herein, unless otherwise
indicated, are amounts exclusive of any amount of contamination that may be
present in the lubricant, derived from the fuel or components of the fuel. In
2.5 general, the amount of oil of lubricating viscosity 50 to 99 percent by
weight,
more commonly 80 to 97 percent by weight or 85 to 95 or 88 to 93 percent by
weight. The amount of diluent oil that may be included within any additive
components is to be considered as added to and a part of the base oil.
Alternatively, the composition of the present invention may itself be provided
as
a concentrate intended to be mixed with further base oil in order to prepare
the
final lubricant composition. In such a case the amount of base oil may be 20
to
80 percent or 21 to 75 or 22 to 70 or to 23 to 60 or 24 to 50 or 25 to 40 or
30 to
percent by weight.
[0020] One additives that will be present in the lubricants of the
present
35 invention is an oil soluble alkali metal salt. The term "oil soluble" is
meant to
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refer to the distribution of the salt in the oil to which it is are added.
While the
present invention is not dependent on any particular theory, it should be
understood that in some instances the salts may dissolve to form true
solutions
while in other instances, micelle dispersions or microemulsions may be formed
which visibly appear to be solutions. Whether a solution, micelle dispersion,
or
microemulsion is formed may be dependent on the particular substance to be
dissolved and the particular medium to which it is added. In any event, the
terms "soluble" and the like are used in this document to refer to solutions,
micelle dispersions, microemulsions, and the like.
110021.1 Alkali metals include lithium, sodium, potassium, rubidium, and
cesium; among these, lithium, sodium, and potassium, and especially sodium,
may be commonly used. Examples of alkali metal salts that may be oil soluble
(besides the detergents disclosed in greater detail below) include alkoxides,
phenates, carboxylates, benzoates, naphthenates, ethyl acetoacetates,
phenylcarbonates, and sulfides, particularly when the anion contains a
hydrocarbyl group of sufficient length to promote oil solubility. This salt
will
typically be present in an amount to provide 0.004 to 0.4 percent by weight
alkali metal to the lubricant, or alternatively 0,01 to 0.2 percent by weight
or
0.03 to 0.1 percent by weight. The amount of the actual salt required will, of
course, depend on the relative amount of the alkali metal in the salt. For
many
suitable materials, the overall amount of this salt may be 0.02 to 2 percent
by
weight of the lubricant, or 0.04 to 1 percent or 0.1 to 0.6 percent.
[0022] The oil soluble alkali metal salt may typically be supplied as a
metal
containing detergent, and in one embodiment an overbased sulfonate detergent,
which may be present along with other metal-containing detergents. Metal-
containing detergents, in general, are typically overbased materials.
Overbased
materials, otherwise referred to as overbased or superbased salts, are
generally
homogeneous Newtonian systems characterized by a metal content in excess of
that which would be present for neutralization according to the stoichiometry
of
the metal and the particular acidic organic compound reacted with the metal.
The overbased materials are prepared by reacting an acidic material (typically
an inorganic acid or lower carboxylic acid, such as carbon dioxide) with a
mixture comprising an acidic organic compound, a reaction medium comprising
at least one inert, organic solvent (e.g., mineral oil, naphtha, toluene,
xylene) for
said acidic organic material, a stoichiometric excess of a metal base, and a
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promoter such as a phenol or alcohol and optionally ammonia. The acidic
organic material will normally have a sufficient number of carbon atoms, for
instance, as a hydrocarbyl substituent, to provide a reasonable degree of
solubility in oil. The amount of excess metal is commonly expressed in terms
of
metal ratio. The term "metal ratio" is the ratio of the total equivalents of
the
metal to the equivalents of the acidic organic compound. A neutral metal salt
has
a metal ratio of one. A salt having 4.5 times as much metal as present in a
normal
salt will have metal excess of 3.5 equivalents, or a ratio of 4.5.
[0023] If
an overbased calcium detergent is present in the lubricant, in
certain embodiments the metal ratio of the overbased calcium detergent may be
2 to 20, or 5 to 12 or 5 to 10, or any combinations of such values as upper or
lower limits.
[00241
Overbased detergents are often characterized by Total Base Number
(TBN). TBN is the amount of strong acid (perchloric or hydrochloric) needed to
neutralize all of the overbased material's basicity, expressed as potassium
hydroxide equivalents (mg KOH per gram of sample). Since overbased
detergents are commonly provided in a foim which contains a certain amount of
diluent oil, for example, 40-50% oil, the actual TBN value for such a
detergent
will depend on the amount of such diluent oil present, irrespective of the
"inherent" basicity of the overbased material. For the purposes of the present
invention, the TBN of an overbased detergent is to be recalculated to an oil-
free
basis. Thus, for instance, a detergent composition having an uncorrected TBN
of 300 and 40% oil content could. have a TBN (oil-free basis) of 500.
Detergents which are useful in the present invention typically have a TBN (oil-
free basis) of 100 to 800, and in one embodiment 150 to 750, and in another,
200 or 400 to 700. If multiple detergents are employed, the overall TBN of the
detergent component (that is, an average of all the specific detergents
together)
will typically be in the above ranges.
[00251 The
overall TBN of the composition, including oil, will derived from
the TBN contribution of the individual components, such. as the dispersant,
the
detergent, and other basic materials, The overall TBN will typically be at
least
5 or at least 7 or at least 10, or sometimes even at least 20. The majority of
the
TBN is typically contributed by the overbased detergent component. In certain
embodiments which include a sodium sulfonate detergent, the TBN contribution
form the sodium sulfonate detergent can be at least 2 or at least 3. Sulfated
ash
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(ASTM D-874) is another parameter often used to characterize such
compositions. Certain of the compositions of the present invention can have
sulfated ash levels of 0.5 to 5% or 0.8 to 4% or to 2%, for instance, greater
than
0.8%, greater than 1.0%, or even greater than 2%,
(00261 The metal compounds useful in making basic metal salts are
generally
any Group 1 or Group 2 metal compounds (CAS version of the Periodic Table
of the Elements). The Group 1 metals of the metal compound include Group la
alkali metals such as sodium, potassium, and lithium (which alkali metals are
particularly useful in the present invention), as well as Group lb metals such
as
copper. The Group 1 metals can be sodium, potassium, lithium and copper, and
in one embodiment sodium or potassium, and in another embodiment, sodium.
The Group 2 metals of the metal base include the Group 2a alkaline earth
metals
such as magnesium, calcium, and barium, as well as the Group 2b metals such.
as zinc or cadmium. In one embodiment the Group 2 metals are magnesium,
calcium, barium, or zinc, and in another embodiments magnesium or calcium.
In certain embodiments the metal is calcium or sodium or a mixture of calcium
and sodium, Generally the metal compounds are delivered as metal salts or
bases. The anionic portion of the compound can be hydroxide, oxide, carbonate,
borate, or nitrate.
[0027] Such overbased materials are well known to those skilled in the art.
Patents describing techniques for making basic salts of sulfonic acids,
carboxylic acids, (hydrocarbyl-substituted) phenols, phosphonie acids, and
mixtures of any two or more of these include U.S. Patents 2,501,731;
2,616,905;
2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162;
3,318,809; 3,488,284; and 3,629,109,
[0028] In one embodiment the lubricants of the present invention can
contain
an overbased sulfonate detergent. Suitable sulfonic acids for the sulfonate
detergent include sulfonic and thiosulfonic acids. Sulfonic acids include the
mono- or polynuclear aromatic or cycloaliphatic compounds. Oil-soluble
sulfonates can be represented thr the most part by one of the following
formulas: R2-T-(S03-), and R.3-(S03-)b, where T is a cyclic nucleus such as
typically benzene; R2 is an aliphatic group such as alkyl, alkenyl, alkox.y,
or
alkoxyalkyl; (R2)-T typically contains a total of at least 15 carbon atoms;
and R3
is an aliphatic hydrocarbyl group typically containing at least 15 carbon
atoms.
35- 3
Examples of R are alkyl, alkenyl, alkoxyalkyl, and carboalkoxyalkyl groups.
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-;
The groups T, R2, and R- in the above formulas can also contain other
inorganic
or organic substituents in addition to those enumerated above such as, fbr
example, hydroxy, mercapto, halogen, nitro, amino, nitroso, sulfide, or
disulfide.
In the above formulas, a and b are at least I. In one embodiment, the oil
soluble
alkali metal salt is provided as an overbased sodium arenesulfonate detergent
which is present in an amount to provide 0.04 to 0.4 percent by weight of the
sodium to the lubricant.
100291 Another overbased material which can be present is an overbased
phenate detergent. The phenols useful in making phenate detergents can. be
represented by the formula. (R1),,-Ar-(01-I)b, wherein R1 is an aliphatic
hydrocarbyl group of 4 to 400 carbon atoms, or 6 to 80 or 6 to 30 or 8 to 25
or 8
to 15 carbon atoms; Ar is an aromatic group (which can be a benzene group or
another aromatic group such as naphthalene); a and b are independently
numbers of at least one, the sum of a and b being in the range of two up to
the
number of displaceable hydrogens on the aromatic nucleus or nuclei of Ar. In
one embodiment, a and b are independently numbers in the range of 1 to 4, or 1
to 2. RI and a are typically such that there is an average of at least 8
aliphatic
carbon atoms provided by the RI groups for each phenol compound. Phenate
detergents are also sometimes provided as sulfur-bridged species.
[0030] Another detergent can be a salicylate detergent. The alkylsalicylate
can be an alkali metal salt or an alkaline earth metal salt of an
alkylsalicylic acid
which can in turn be prepared from an alkylphenol by Kolbe-Schmitt reaction.
The alkylphenol can be prepared by a reaction of a-olefin having 8 to 30
carbon
atoms (mean number) with phenol. Alternatively, calcium salicylate can be
produced by direct neutralization of alkylphenol and subsequent carbonation..
[0031] In one embodiment, the overbased material is an overbased
detergent
selected from the group consisting of overbased salixarate detergents,
overbased
saligenin detergents, overbased salicylate detergents, and overbased
glyoxylate
detergents, and mixtures thereof. Overbased saligenin detergents are commonly
overbased magnesium salts which are based on saligenin derivatives. A general
example of such a saligenin derivative can be represented by the formula
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OM OM
X = -Y. = ==
== 0 = = X
0 =
= / = =
Rip L m
wherein X comprises -CHO or -CH2OH, Y comprises -CH2- or -CH2OCH2-, and
wherein such -CHO groups typically comprise at least 10 mole percent of the X
and Y groups; M is hydrogen, ammonium, or a valence of a metal ion, RI is a
hydrocarbyl group containing 1 to 60 carbon atoms, m is 0 to typically 10, and
each p is independently 0, 1, 2, or 3, provided that at least one aromatic
ring
contains an Ri substituent and that the total number of carbon atoms in all RI
groups is at least 7. When m is 1 or greater, one of the X groups can be
hydrogen. In one embodiment, M is a valence of a Mg ion (that is, 1/2 mole of
mg2f-,
) or a mixture of Mg and hydrogen. Other metals include alkali metals
such as lithium, sodium, or potassium; alkaline earth metals such as calcium
or -
barium; and other metals such as copper, zinc, and tin.
[0032] As used herein, the expression "represented by the formula"
indicates
that the formula presented is generally representative of the structure of the
chemical in question. However, it is well known that minor variations can
occur, including in particular positional isomerization, that is, location of
the X,
Y, and R groups at different position on the aromatic ring from those shown in
the structure. The expression "represented by the formula" is expressly
intended to encompass such variations.
[0033] Saligenin detergents are disclosed in greater detail in U.S. Patent
6,310,009, with special reference to their methods of synthesis (Column 8 and
Example 1) and amounts of the various species of X and Y (Column 6).
[0034] Salixarate detergents are overbased materials that can be
represented
by a substantially linear compound comprising at least one unit of fonnula (I)
or
formula (II):
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.R.4.
HO R1 = = = = R5 =
COOR3 R6
= (I) (II)
each end of the compound having a terminal group of formula (III) or (W):
R4
(R2)j
HO
COOR3 R6
(iii) (IV)
such groups being linked by divalent bridging groups A, which may be the same
or different for each linkage; wherein in formulas (I)-(IV) R3 is hydrogen or
a
hydrocarbyl group; R2 is hydroxyl. or a hydrocarbyl group and j is 0, 1, or 2;
R'
is hydrogen, a hydrocarbyl group, or a hetero-substituted hydrocarbyl group;
either R4 is hydroxyl and R5 and R7 are independently either hydrogen, a
hydrocarbyl group, or hetero-substituted hydrocarbyl group, or else R5 and R7
are both hydroxyl and R4 is hydrogen, a hydrocarbyl group, or a hetero-
substituted hydrocarbyl group; provided that at least one of R.4, R5, R6 and
R7 is
hydrocarbyl containing at least 8 carbon atoms; and wherein the molecules on
average contain at least one of unit (I) or (III) and at least one of unit
(II) or (IV)
and the ratio of the total number of units (I) and (III) to the total number
of units
of (II) and (W) in the composition is about 0,1:1 to about 2:1. The divalent
bridging group "A," which may be the same or different in each occurrence,
includes -CH2- (methylene bridge) and -CH2OCH2- (ether bridge), either of
which
may be derived from formaldehyde or a formaldehyde equivalent (e.g., paraform,
formalin),
[0035] Salixarate derivatives and methods of their preparation are
described
in greater detail in U.S. patent number 6,200,936 and PCT Publication WO
01./56968. It is believed that the salixarate derivatives have a predominantly
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linear, rather than macrocyclic, structure, although both structures are
intended
to be encompassed by the term "salixarate."
[00361 Glyoxylate detergents are similar overbased materials which are
based on an anionic group which, in one embodiment, may have the structure
C(0)0-
H
OH
. C I
=
= rt
wherein each R is independently an alkyl group containing at least 4, e.g., at
least 8 carbon atoms, provided that the total number of carbon atoms in all
such
R groups is at least 12, or alternatively at least 16 or 24. Alternatively,
each R
can be an olefin polymer substituent. The acidic material upon from which the
overba.sed glyoxylate detergent is prepared is the condensation product of a
hydroxyaromatic material such as a hydrocarbyl-substituted phenol with a
carboxylic reactant such as glyoxylic acid. and other omega-oxoalkanoic acids.
Overbased glyoxylic detergents and their methods of preparation are disclosed
in greater detail in U.S, Patent 6,310,011 and references cited therein.
[00371 The overbased detergent can also be an overbased salicylate. The
salicylic acids may be hydrocarbyl-substituted salicylic acids, such as
aliphatic
hydrocarbon-substituted salicylic acids wherein each substituent contains an
average of at least 8 carbon atoms per substituent and 1 to 3 substituents per
molecule. The substituents can be polyalkene substituents, where polyalkenes
include homopolymers and interpolymers of polymerizable olefin monomers of
2 to about 16, or 2 to 6, or 2 to 4 carbon atoms. The olefins may be
monoolefins
such as ethylene, propylene, 1-butene, isobutene, and 1-octene; or a
polyolefinic
monomer, such as diolefinic monomer, such 1,3-butadiene and isoprene. In one
embodiment, the hydrocarbyl substituent group or groups on the salicylic acid.
contains 7 to 300 carbon atoms and can be an alkyl group having a molecular
weight of 150 to 2000. The polyalkenes and polyalkyl groups are prepared by
conventional procedures, and substitution of such groups onto salicylic acid
can
be effected by known methods. Overba.sed salicylate detergents and their
methods of preparation are disclosed in U.S. Patents 4,719,023 and 3,372,116.
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[00381
Other overbased detergents can include overbased detergents having a
Mannich base structure, as disclosed in U.S, Patent 6,569,818.
[0039] The
total amount of the overbased detergent or detergents in the
formulations of the present invention is typically at least 0,6 weight percent
on
an oil-free basis. in other embodiments, it can be present in amounts of 0,7
to 5
weight percent or 1 to 3 weight percent. Either a single detergent or multiple
detergents can he present.
[0040]
Another lubricant additive is a dispersant. Dispersants are well
known in the field of lubricants and include primarily what is known as
ashless
dispersants and polymeric dispersants. Ashless
dispersants are so-called
because, as supplied, they do not contain metal and thus do not normally
contribute to sulfated ash when added to a lubricant. However they may, of
course, interact with ambient metals once they are added to a lubricant which.
includes metal-containing species. Ashless dispersants are characterized by a
polar group attached to a relatively high molecular weight hydrocarbon chain.
Typical ashless dispersants include N-substituted long chain alkenyl
succinimides, having a variety of chemical structures including typically
0 9
RLCH---c -CH-R
-
C112-C CI H2
where each RI is independently an alkyl group, frequently a polyisobutylene
group with a molecular weight of 500-5000, and R2 are alkylene groups,
commonly ethylene (C2H4) groups. Such molecules are commonly derived from
reaction of an alkenyl acylating agent with a polyamine, and a wide variety of
linkages between the two moieties is possible beside the simple imide
structure
shown above, including a variety of amides and quaternary ammonium salts.
Also, a variety of modes of linkage of the RI groups onto the imide structure
are
possible, including various cyclic linkages. The ratio of the carbonyl groups
of
the acylating agent to the nitrogen atoms of the amine may be 1:0,5 to 1:3,
and in
other instances 1:1 to 1:2.75 or 1:1.5 to 1:2.5. Succinimide dispersants are
more
fully described in U.S. Patents 4,234,435 and 3,172,892 and in EP 0355895,
[0041]
Another class of ashless dispersant is high molecular weight esters.
These materials are similar to the above-described succinimides except that
they
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may be seen as having been prepared by reaction of a hydrocarbyl acylating
agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or
sorbitol. Such materials are described in more detail in U.S. Patent
3,381,022.
[0042]
Another class of ashless dispersant is Mannich bases, These are
materials which are formed by the condensation of a higher molecular weight,
alkyl substituted phenol, an alkylene polyamine, and an aldehyde such as
formaldehyde. Such materials may have the general structure
OH
OH
.-------ICH2-N[1-(R2N/-1)x-R2NHCH2
= .
R1
(including a variety of isomers and the like) and are described in more detail
in
U.S. Patent 3,634,515.
[00431
Other dispersants include polymeric dispersant additives, which are
generally hydrocarbon-based polymers which contain polar functionality to
impart dispersancy characteristics to the polymer,
10044]
Dispersants can also be post-treated by reaction with any of a variety
of agents. Among these are urea, thiourea., dimercaptothiadiazoles, carbon
disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted
SUCCirliC anhydrides, nitriles, epoxides, boron compounds, and phosphorus
compounds. References detailing such treatment are listed in U.S. Patent
4,654,403,
[00451 The lubricant
composition will typically also include a metal salt of a
phosphorus acid. Metal salts of the formula
P M
R90
wherein R8 and R9 are independently hydrocarb:s,71 groups containing 3 to 30
or
to 20, to 16, or to 14 carbon atoms are readily obtainable by the reaction of
phosphorus pentasulfide (P2S5 or :P4S 10) and an alcohol or phenol to form an
0,0-dihydrocarbyl phosphorodithioic acid corresponding to the formula
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R.80 S
\ 11
P ¨ SH
,
,
,
R70
The reaction involves mixing, at a temperature of 20 C to 200 C, at least four
moles of an alcohol or a phenol with one mole of phosphorus pentasulfide.
Hydrogen sulfide is liberated in this reaction. The acid is then reacted with
a
basic metal compound to form the salt. The metal M, having a valence n,
-- generally is aluminum, lead, tin, manganese, cobalt, nickel, zinc, or
copper, and
in one embodiment, zinc. The basic metal compound thus may be zinc oxide,
and the resulting metal compound is represented by the formula
(
R80 s
\ 0
/P S ' ______ Zn
R90
2
The R and R9 groups are independently hydrocarb:,,,1 groups that. may be free
-- from acetylenic and usually also from ethylenic unsaturation, They are
typically
alkyl, cycloalkyl, aralkyl or alkaryl group and have 3 to 20 carbon atoms,
such
as 3 to 16 carbon atoms or up to 13 carbon atoms, e.g., 3 to 12 carbon atoms.
The alcohol which reacts to provide the R8 and R9 groups can be a mixture of a
secondary alcohol and a primary alcohol, for instance, a mixture of 2.-
-- ethylhexanol and isopropan.ol or, alternatively, a mixture of secondary
alcohols
such as isopropanol and 4-inethy1-2-pentanol. Such materials are often
referred
to as zinc dialkyldithiophosphates or simply zinc dithiophosphates. They are
well known and readily available to those skilled in the art of lubricant
formulation.
[00461 The amount of the metal salt of a phosphorus acid in a completely
formulated lubricant, if present, will typically be 0.1 to 4 percent by
weight,
such as 0,5 to 2 percent by weight or 0.75 to 1.25 percent by weight. Its
concentration in a concentrate will be correspondingly increased, to, e.g., 5
to
20 weight percent.
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[0047] The
oil of lubricating viscosity will generally be selected so as to
provide, among other properties, an appropriate viscosity and viscosity index.
Most modern engine lubricants are multigrade lubricant which contain viscosity
index improvers to provide suitable viscosity at both low and high
temperatures.
While the viscosity modifier is sometimes considered a part of the base oil,
it is
more properly considered as a separate component, the selection of which is
within the abilities of the person skilled in the art.
[0048]
Viscosity modifiers generally are polymeric materials characterized
as being hydrocarbon-based polymers generally having number average
-- molecular weights between 25,000 and 500,000, e.g., between 50,000 and
200,000,
[0049]
Hydrocarbon polymers can be used as viscosity index improvers.
Examples include homopolyiners and copolymers of two or more monomers of
C2 to C30, e.g., C2 to C8 olefins, including both alphaolefins and internal
-- olefins, which may be straight or branched, aliphatic, aromatic, alkyl-
aromatic,
or cycloaliphatic. Examples include ethylene-propylene copolymers, generally
referred to as OCP's, prepared by copolymerizing ethylene and propylene by
known processes.
[0050]
Hydrogenated styrene-conjugated dime copolymers are another class
of viscosity modifiers. These polymers include polymers which are
hydogenated or partially hydrogenated hom.opolymers, and also include random,
tapered, star, and block interpolymers. The term "styrene" includes various
substituted styrenes. The conjugated diene may contain four to six carbon
atoms
and may include, e.g.. piperylene, 2,3-dimethy1-1,3-butadiene, chloroprene,
-- isoprene, and 1,3-butadiene. Mixtures of such conjugated dienes are useful.
The styrene content of these copolymers may be 20% to 70% by weight or 40%
to 60%, and the aliphatic conjugated diene content may be 30% to 80% or 40%
to 60%. These copolymers can be prepared by methods well known in the art
and are typically hydrogenated to remove a substantial portion of their
olefinic
-- double bonds.
[0051]
Esters obtained by copolymerizing styrene and maleic anhydride in
the presence of a free radical initiator and thereafter esterifying the
copolymer
with a mixture of C4-18 alcohols also are useful as viscosity modifying
additives in. motor oils. Likewise, polymethacrylates (PMA) are used as
-- viscosity modifiers, These materials are typically prepared from mixtures
of
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methacrylate monomers having different alkyl groups, which may be either
straight chain or branched chain groups, and may contain I to 18 carbon atoms
or mixtures thereof. C1-C7 alkyl groups may be used in admixture with C8-C 18
or
higher alkyl groups.
[0052] When
a small amount of a nitrogen-containing monomer is
copolymerized with alkyl methacrylates, dispersancy properties are
incorporated
into the product. Thus, such a product has the multiple function of viscosity
modification, pour point depressancy and dispersancy and are sometimes
referred to as dispersant-viscosity modifiers.
Vinyl pyridine, N-vinyl
pyrrolidone and N,NT-dimethylaminoethyl methacrylate are examples of
nitrogen-containing monomers. Polyacrylates obtained from the polymerization
or copolymerization of one or more alkyl acrylates also are useful as
viscosity
modifiers. Dispersant viscosity modifiers may also be interpolymers of
ethylene
and propylene which are grafted with an active monomer such as maleic
anhydride and then derivatized with an alcohol or an amine or grafted with
nitrogen compounds.
[00531
Antioxidants may also be present. Antioxidants encompass phenolic
antioxidants, which may be of the general the formula
fri
(R4),
wherein R4 is an alkyl group containing 1 to 24, or 4 to 18, carbon atoms and
a
is an integer of 1 to 5 or I to 3, or 2. The phenol may be a butyl substituted
phenol containing 2 or 3 t-butyl groups, such as
=
0
The para position may also be occupied by a hydrocarbyl group or a group
bridging two aromatic rings. In certain embodiments the para position is
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occupied by an ester-containing group, such as, for example, an antioxidant of
the formula
t-alkyl
0
HO
53
wherein i
R s a hydrocarbyl group such as an alkyl group containing, e.g., 1 to
18 or 2 to 12 or 2 to 8 or 2 to 6 carbon atoms; and t-alkyl can be t-butyl.
Such
antioxidants are described in greater detail in U.S. Patent 6,559,105.
[0054] Antioxidants also include aromatic amines, such as those of the
formula
NFIR6
= =
__________________________________________ R6
wherein R5 can be an aromatic group such as a phenyl group, a naphthyl group,
or a phenyl group substituted by R7, and R6 and R7 can be independently a
hydrogen or an alkyl group containing 1 to 24 or 4 to 20 or 6 to 12 carbon
atoms. In one embodiment, an aromatic amine antioxidant can comprise an
alkylated diphenylamine such as nonylated diphenylamine of the formula
CAI 9 C91119
or a mixture of a di-nonylated amine and a mono-nonylated amine.
[0055] Antioxidants also include sulfurized olefins such as mono-, or
disulfides or mixtures thereof. These materials generally have sulfide
linkages
having I. to 10 sulfur atoms, for instance, 1 to 4, or 1 or 2. Materials which
can
be sulfurized to form the sulfurized organic compositions of the present
invention include oils, fatty acids and esters, olefins and polyolefins made
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thereof, terpenes, or Diels-Alder adducts. Details of methods of preparing
some
such sulfurized materials can be found in U.S. Pat. Nos. 3,471,404 and
4,191,659.
[0056]
Molybdenum compounds can also serve as antioxidants, and these
materials can also serve in various other functions, such as antiwear agents.
The
use of molybdenum and sulfur containing compositions in lubricating oil
compositions as antiwear agents and antioxidants is known. U.S. Pat. No.
4,285,822, for instance, discloses lubricating oil compositions containing a
molybdenum and sulfur containing composition prepared by (1) combining a
polar solvent, an acidic molybdenum compound and an oil-soluble basic
nitrogen compound to form a molybdenum-containing complex and (2)
contacting the complex with carbon disulfide to foint the molybdenum and
sulfur containing composition.
[0057] In
certain embodiments of the present invention, a aminic antioxidant
may be present in amounts of at least 0.5 weight percent, or at least 1 or 2
weight percent. In certain embodiments the amount of phenolic antioxidant will
be less than 2 percent by weight or less than 1 percent or less than 0.5
percent
by weight in the lubricant, or less than 0.3, 0.1, 0.05, or 0.01 percent by
weight,
or the lubricant may be substantially free from phenolic antioxidant, i.e., an
amount near zero percent characteristic of incidental contamination..
Appropriate minimum amounts of hindered phenolic antioxidants may include
0.005, 0,01, 0.05, or 0.1 percent by weight. It is recognized, however, that
certain amounts of hindered phenolic antioxidants may be desirable for other
performance properties. In that case, amounts as high as 0.3 or 0.5 or 0.8
percent by weight may be acceptable. It is desirable, in some embodiments,
that
the amount of the aminic antioxidant be equal to or greater than that of the
hindered phenolic antioxidant. In certain embodiments, the amount of aminic
antioxidant may be greater than 0.5% and the amount of phenolic antioxidant
may be less than 1% and/or the amount of aminic antioxidant may be greater
than the amount of phenolic antioxidant. in certain embodiments the amount of
the aminic antioxidant exceeds that of the hindered phenolic antioxidant by at
least 0.5%, e.g., 1.5% aminic and 1.0% hindered phenolic. The various
numerical limits and relative amounts of antioxidants disclosed herein may be
combined one with another. Typical amounts of antioxidants will, of course,
depend on the specific antioxidant and its individual effectiveness, but
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illustrative total amounts may also be 0.01 to 5 percent by weight or 0.15 to
4.5
percent or 0.2 to 4 percent.
[00581 Other conventional components may also be present, including
pour
point depressants; friction modifiers such as fatty esters; metal
deactivators; rust
inhibitors, high pressure additives, anti-wear additives, and antifoam agents.
Any of these materials can be present or can be eliminated, if desired. In one
embodiment a rust inhibitor such as a hydroxy-containing ether or a tartrate
or
citrate ester may be present in an amount of 0.02 to 2 percent by weight.
[0059] Antioxidants (or oxidation inhibitors), including hindered
phenolic
antioxidants such as 2,6-di-t-butylphenol and 2,6-di-t-butylphenol with
various
substituents at the 4 position, including those derived from acrylate ester,
secondary aromatic amine antioxidants such as dialkyl (e.g., dinonyl)
diphenylamine, sulfurized phenolic antioxidants, oil-soluble copper compounds,
phosphorus-containing antioxidants, molybdenum compounds such as the Mo
dithiocarbamates, organic sulfides, disulfides, and polysulfides. An extensive
list of antioxidants is found in U.S. Patent 6,251,840.
[0060] The role of the corrosion inhibitor is to preferentially adsorb
onto
metal surfaces to provide protective film or to neutralize corrosive acids.
Examples of these include, but are not limited to, ethoxylates, alkenyl SW6-
flit:
half ester acids, zinc dithiophosphates, metal phenolates, basic metal
sulfonates,
fatty acids, amines, triazoles, and dimercaptothiadiazole derivatives.
100611 Anti-foam agents used to reduce or prevent the formation of
stable
foam include silicones or organic polymers. Examples of these and additional
anti-foam compositions are described in "Foam Control Agents", by Henry T.
Kerner (Noyes Data Corporation, 1976), pages 125-162.
[0062] Pour point depressants are used to improve the low temperature
properties of oil-based compositions. See, for example, page 8 of "Lubricant
Additives" by CAT. Smalheer and R. Kennedy Smith (Lezius Hiles Co.
publishers, Cleveland, Ohio, 1967), Examples of useful pour point depressants
are polymethacrylates; polyacrylates; polyaerylamides; condensation products
of haloparaffin waxes and aromatic compounds; vinyl carboxylate polymers;
and terpolymers of dialkylfumarates, vinyl esters of fatty acids and alkyl
vinyl
ethers. Pour point depressants are described in US. Patents including
3,250,715.
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[00631 As
used herein, the term "hydrocarbyl substituent" or "hydrocarbyl
group" is used in its ordinary sense, which is well-known to those skilled in
the
art. Specifically, it refers to a group having a carbon atom directly attached
to
the remainder of the molecule and having predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
[00641
hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),
alicyciic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-,
aliphatic-,
and alicyclic-substituted aromatic substituents, as well as cyclic
substituents
wherein the ring is completed through another portion of the molecule (e.g.,
two
substituents together form a ring);
[0065]
substituted hydrocarbon substituents, that is, substituents
containing non-hydrocarbon groups which, in the context of this invention, do
not alter the predominantly hydrocarbon nature of the substituent (e.g., halo
(especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto,
nitro,
nitroso, and sultbxy);
10066]
hetero substituents, that is, substituents whit* while having a
predominantly hydrocarbon character, in the context of this invention, contain
other than carbon in a ring or chain otherwise composed of carbon atoms and
encompass substituents as pyridyl, furyl, thienyl and imidazolyl. Heteroatoms
include sulfur, oxygen, and nitrogen. In general, no more than two or no more
than one, non-hydrocarbon substituent will be present for every ten carbon
atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon
substituents in the hydrocarbyl group.
10067] It
is known that some of the materials described above may interact in
the final formulation, so that the components of the final formulation may be
different from those that are initially added. For instance, metal ions (of,
e.g., a
detergent) can migrate to other acidic or anionic sites of other molecules.
The
products formed thereby, including the products formed upon employing the
composition of the present invention in its intended use, may not be
susceptible
of easy description. Nevertheless, all such modifications and reaction
products
are included within the scope of the present invention; the present invention
encompasses the composition prepared by admixing the components described
above.
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EXAMPLES
[00681 Lubricants are prepared in a standard lubricant formulation
comprising a mixture of polyalphaolefins (4 and 6 mm2ls (cSt)) as the base
oil,
as well as a viscosity modifier, a mixture of calcium and magnesium
detergents,
a succinimide dispersant, 0.5% aminic antioxidant, 0.3 percent phenolic
antioxidant, a sulfurized olefin, a zinc dialkyldithiophosphate, a fatty amide
friction modifier, a pour point depressant, and a foam inhibitor. A small
amount
of mineral oil is also present, supplied as diluent oil with some of the
additive
components. A lubricant according to the present invention is also prepared
containing an overbased sodium sulfonate, in amounts as shown in the table
below:
[0069] The test lubricants are subject to a bench oxidation test in
which a 90
g samples of the oil, contaminated with 140 ppm Fe naphthenate, is placed into
a long test tube equipped with water condenser. The tube is immersed in a
170 C oil bath and air is delivered through a glass tube to the bottom of the
sample at the rate of 10 Llhour. Samples of the fluid (10 mL) are removed at
the time intervals noted and analyzed for kinematic viscosity at 40 C.
Viscosity (KV40) as a function of time and detergent composition
Detergent Composition', wt. % Ex: I
(comparative) 2
Na sulfonate (448 TBN, in.cl, 41% diluent oil, 0 0,2
19,45 wt f.VoNa)
Ca sulfonate (400 TBN, incl. 42% diluent oil) 0.4 0.2
Other Ca and Mg sulfonate and phenate 4.7 4,7
detergents, including diluent oil
Time Test Results: KV40 (mm2/s) KV40
0 67.2 71,7
72 hr 48.2 54.2
96 hr 54.2 52.0
120 hr ----------------------------------------- 53.4 47.1
144 hr 80.1 46.9
168 hr ----------------------------------------- >500 53.2
a. TBN and % reported on oil-containing basis
[00701 The results show that the presence of the sodium sulfonate leads to
significantly improved retention of viscosity.
23
CA 02724286 2015-11-06
10071] The lubricant formulation of comparative example 1, and a second
lubricant according to example 2, containing the sodium sulfonate detergent,
are used to lubricate a 1.81., turbocharged engine. The engine is fueled with
a
gasoline which is not particularly "dirty" with respect to diesel sludge
formation. After running for 168 hours with each of the lubricant samples, the
engine is disassembled and inspected. The rocker cover and piston grooves are
assigned merit ratings for sludge and deposits on a scale of 0 10, with a
rating
of 10 indicating no sludge or deposits.
Sludge Ratings
Base lubricant with Na sulfonate
(Comp Ex. 1) (Ex. 2)
Rocker cover 9.30 9.43
Piston groove 1 Oa Oa
Piston groove 2 5.54 6.49
Piston groove 3 2.86 5.19
a. Rating of 0 for groove 1 indicates a dirty groove, which is an expected
result for this test.
The results show a significant reduction in the amount of sludge in piston
grooves 2 and 3, as well as a significant improvement for the rocker cover,
100721
The mention of any document is not an admission that such document
qualifies as prior art or constitutes the general knowledge of the skilled
person in
any jurisdiction. Except in the Examples, or where otherwise explicitly
indicated,
all numerical quantities in this description specifying amounts of materials,
reac-
tion conditions, molecular weights, number of carbon atoms, and the like, are
to
be understood as modified by the word "about." Unless otherwise indicated,
each
chemical or composition referred to herein should be interpreted as being a
commercial grade material which may contain the isomers, by-products,
derivatives, and other such materials which are normally understood to be
present
in the commercial grade. However, the amount of each chemical component is
presented exclusive of any solvent or diluent oil, which may be customarily
present in the commercial material, unless otherwise indicated. It is to be
understood that the upper and lower amount, range, and ratio limits set forth
herein may be independently combined. Similarly, the ranges and amounts for
each element of the invention can be used together with ranges or amounts for
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any of the other elements. As used herein, the expression "consisting
essentially
or permits the inclusion of substances that do not materially affect the basic
and
novel characteristics of the composition under consideration,
