Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LUBRICATING COMPOSITION CONTAINING ASHFREE ANTIWEAR AGENT
BASED ON HYDROXYPOLYCARBOXYLIC ACID DERIVATIVE AND A
MOLYBDENUM COMPOUND
FIELD OF INVENTION
The invention provides a lubricating composition containing an oil of
lubricating viscosity, an oil soluble molybdenum compound, and an ashless
antiwear agent. The invention further provides for a new antioxidant. The
lubricating composition is suitable for lubricating an internal combustion
engine.
BACKGROUND OF THE INVENTION
[0001] Engine manufacturers have focused on improving engine design in
order to improve fuel economy and efficiency (typically, based on Federal
Corporate Average Fuel Economy (CAFE) standards). Whilst improvements in
engine design and operation have contributed, improved formulation of engine
oil lubricant may also improve fuel economy and efficiency. Lubricants
function
to reduce and disperse engine deposits which accumulate when the engines are
running. They also serve to reduce the friction between sliding moving parts
(typically metallic or ceramic) that are in contact.
[0002] It is well known for lubricating oils to contain a number of
additives
(including antiwear agents, antioxidants, dispersants, detergents etc.) used
to
protect the mechanical devices such as internal combustion engines from wear,
oxidation, soot deposits and acidity build up. A common antiwear additive for
engine lubricating oils is zinc dialkyldithiophosphate (ZDDP). It is believed
that
ZDDP antiwear additives protect the engine by forming a protective film on
metal surfaces. ZDDP is also believed to have a detrimental impact on fuel
economy and efficiency. Consequently, engine lubricants also contain friction
modifier to obviate the detrimental impact of ZDDP on fuel economy and
efficiency. Both ZDDP and friction modifier function by adsorption on sliding
surfaces, and each may interfere with each other's respective functions.
[0003] Further, engine lubricants containing phosphorus compounds and
sulphur have been shown to contribute in part to particulate emissions, and
emissions of other pollutants. In addition, sulphur and phosphorus tend to
poison the catalysts used in catalytic converters, resulting in a reduction in
performance of said catalysts.
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[0004] With increasing control of emissions (often associated with
contributing to NO formation, Sox formation, formation of sulphated ash and
reducing the efficiency of after-treatment catalytic converters) there is a
desire
towards reduced amounts of sulphur, phosphorus and sulphated ash in engine
oils. However, reducing the levels of antiwear additives such as ZDDP, is
likely
to increase wear and result in other detrimental performance of an engine.
[0005] In addition, as technology develops, components of an engine are
exposed to more severe operating conditions. Operating conditions may include
higher power density engines, use of turbo chargers, use of alternative fuels
and
the like. Under many severe operating conditions, oxidation of lubricant and
components occurs more readily. Thus there is a need to reduce oxidation, that
in turn may also increase equipment longevity, or reliability.
[0006] International Publication WO 2005/087904 discloses a lubricant
composition containing at least one hydroxycarboxylic acid ester or hydroxy
polycarboxylic acid. The lubricant composition disclosed may also contain zinc
dihydrocarbyldithiophosphates, or other phosphorous-containing additives such
as
trilauryl phosphate or triphenylphosphorothionate. The lubricant composition
has
anti-wear or anti-fatigue properties.
[0007] International Publication WO 2006/044411 discloses a low-sulphur,
low-phosphorus, low-ash lubricant composition suitable for lubricating an
internal combustion engine, containing a tartrate ester, or amide having 1 to
150
carbon atoms per ester of amide group.
[0008] US Patent 5,338,470 discloses alkylated citric acid derivatives
obtained as a reaction product of citric acid and an alkyl alcohol or amine.
The
alkylated citric acid derivative is effective as an antiwear agent and
friction
modifier.
[0009] U.S. Patent 4,237,022 discloses tartrimides useful as additives in
lubricants and fuels for effective reduction in squeal and friction as well as
improvement in fuel economy.
[0010] U.S. Patent 4,952,328 discloses lubricating oil compositions for
internal combustion engines, comprising (A) oil of lubricating viscosity, (B)
a
carboxylic derivative produced by reacting a succinic acylating agent with
certain amines, and (C) a basic alkali metal salt of sulphonic or carboxylic
acid.
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[0011] U.S. Patent 4,326,972 discloses lubricant compositions for improving
fuel economy of internal combustion engines. The composition includes a
specific sulphurised composition (based on an ester of a carboxylic acid) and
a
basic alkali metal sulphonate.
[0012] International Publication No.: W02008/070307 discloses malonate esters
suitable
as antiwear agents.
[0013] Canadian Patent CA 1 183 125 discloses lubricants for gasoline
engines containing alkyl-ester tartrates, where the sum of carbon atoms on the
alkyl groups is at least 8.
[0014] Consequently, it would be desirable to provide a lubricating
composition capable of providing at least one of (i) reducing or preventing
phosphorus emissions, (ii) reducing or preventing sulphur emissions, (ii)
wholly
or partially replacing ZDDP in lubricating oils, (iii) improving fuel economy,
(iv) fuel economy retention/efficiency, and (v) oxidation control. The present
invention provides an antiwear agent capable of achieving at least one of (i),
(ii)
(iii), (iv), and (v). In addition it may also be desirable for the antiwear
agent to
not have a detrimental affect on other components of a mechanical device. It
may also be desirable for the antiwear agent to have antioxidant performance.
SUMMARY OF THE INVENTION
[0015] In one embodiment the invention provides a lubricating composition
comprising an oil of lubricating viscosity, an oil-soluble molybdenum
compound, and an ashless antiwear agent represented by Formula (1):
(11O
RI ¨Y ___________________ )(X), _______ r R2
Formula (1)
wherein
Y and Y' are independently -0-, >NH, >NR3, or an imide group formed
by taking together both Y and Y' groups and forming a R1-N< group between
two >C=0 groups;
X is independently -Z-0-Z'-, >CH2, >CHR4, >CR4R5, >C(OH)(CO2R2),
>C(CO2R2)2, ' CCI 12(.07R2, or >CHOR6;
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Z and Z' are independently >CH2, >CHR4, >CR4R5, >C(OH)(CO2R2), or
>CHOR6;
n is 0 to 10, or 1 to 8, or 1 to 6, or 2 to 6, or 2 to 4, with the proviso
that
when n=1, X is not >CH2, and when n=2, both X's are not simultaneously >CH2;
m is 0 or 1;
Rl is independently hydrogen or a hydrocarbyl group, typically containing
1 to 150, 4 to 30, or 6 to 20, or 10 to 20, or 11 to 18, or 8 to 10 carbon
atoms,
with the proviso that when Rl is hydrogen, m is 0, and n is more than or equal
to
1;
R2 is a hydrocarbyl group, typically containing 1 to 150, 4 to 30, or 6 to
20, or 10 to 20, or 11 to 18, or 8 to 10 carbon atoms;
R3, R4 and R5 are independently hydrocarbyl groups or hydroxy-
containing, hydrocarbyl groups or carboxyl-containing hydrocarbyl groups; and
R6 is hydrogen or a hydrocarbyl group, typically containing 1 to 150, or 4
to 30 carbon atoms.
[0016] In one embodiment the lubricating composition is characterised as
having at least one of (i) a sulphur content of 0.8 wt % or less, (ii) a
phosphorus
content of 0.2 wt % or less, or (iii) a sulphated ash content of 2 wt % or
less.
[0017] In one embodiment the invention the lubricating composition is
characterised as having (i) a sulphur content of 0.5 wt % or less, (ii) a
phosphorus content of 0.1 wt % or less, and (iii) a sulphated ash content of
1.5
wt % or less.
[0018] In one embodiment the invention provides a method of lubricating an
internal combustion engine comprising, supplying to the internal combustion
engine a
lubricating compositions as disclosed herein.
[0019] In one embodiment the invention provides for the use of a
lubricating
composition as disclosed herein for providing at least one of (i) reducing or
preventing phosphorus emissions, (ii) reducing or preventing sulphur
emissions,
(ii) wholly or partially replacing ZDDP in lubricating oils, (iii) improving
fuel
economy, and (iv) fuel economy retention/efficiency.
[0020] In one embodiment the invention provides for the use of a compound
of
Formula (1) as an antioxidant in a lubricant, wherein the compound of Formula
(1)
may be represented by:
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/0\ 0
11 11
11: y \ 1 oon
Y'-R2
/ m
wherein
Y and Y' are independently -0-, >NH, >NR3, or an imide group formed
by taking together both Y and Y' groups and forming a R1-N< group between
two >C=0 groups;
X is independently -Z-0-Z'-, >CH2, >CHR4, >CR4R5, >C(OH)(CO2R2),
>C(CO2R2)2, or >CHOR6;
Z and Z' are independently >CH2, >CHR4, >CR4R5, >C(OH)(CO2R2), or
>CHOR6;
n is 0 to 10, or 1 to 8, or 1 to 6, or 2 to 6, or 2 to 4, with the proviso
that
when n=1, X is not >CH2, and when n=2, both X's are not >CH2;
m is 0 or 1;
Rl is independently hydrogen or a hydrocarbyl group, typically containing
1 to 150, 4 to 30, or 6 to 20, or 10 to 20, or 11 to 18, or 8 to 10 carbon
atoms,
with the proviso that when Rl is hydrogen, m is 0, and n is more than or equal
to
1;
R2 is a hydrocarbyl group, typically containing 1 to 150, 4 to 30, or 6 to
20, or 10 to 20, or 11 to 18, or 8 to 10 carbon atoms;
R3, R4 and R5 are independently hydrocarbyl groups; and
R6 is hydrogen or a hydrocarbyl group, typically containing 1 to 150, or 4 to
30
carbon atoms.
[0021] In one embodiment the invention provides for the use of the compound
of
Formula (1) as an antioxidant in a lubricant, wherein the compound of Formula
(1) is
an ester (such as a monoester, a diester or a triester).
[0022] In one embodiment the invention provides for the use of the compound
of
Formula (1) as an antioxidant in a lubricant, wherein the compound of Formula
(1) is
not a citrate.
[0023] In one embodiment the invention provides for the use of a tartaric
acid
derivative (typically a tartrate ester) as an antioxidant in a lubricant.
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[0024] In one
embodiment the invention provides for the use of the compound of
Formula (1) (typically a tartaric acid derivative) as an antioxidant in an
internal
combustion engine lubricant.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The
present invention provides a lubricating composition and a
method for lubricating an engine as disclosed above.
Oil-Soluble Molybdenum Compound)
[0026] The oil-
soluble molybdenum compound may have the functional
performance of an antiwear agent, an antioxidant, a friction modifier, or
mixtures
thereof
Typically, the oil-soluble molybdenum compound includes
molybdenum dithiocarbamates, molybdenum dialkyldithiophosphates, amine
salts of molybdenum compounds, molybdenum xanthates, molybdenum
sulphides, molybdenum carboxylates, molybdenum alkoxides, or mixtures
thereof. The molybdenum sulphides include molybdenum disulphide. The
molybdenum disulphide may be in the form of stable dispersions. In one
embodiment the oil-soluble molybdenum compound may be selected from the
group consisting of molybdenum dithiocarbamates, molybdenum
dialkyldithiophosphates, amine salts of molybdenum compounds, and mixtures
thereof In one embodiment the oil-soluble molybdenum compound is a
molybdenum dithiocarbamate .
[0027] Suitable
examples of molybdenum dithiocarbamates which may be
used as an antioxidant include commercial materials sold under the trade names
such as Molyvan 822TM and MolyvanTM A from R. T. Vanderbilt Co., Ltd., and
Adeka Sakura-LubeTM S-100, S-165, S-515, and S-600 from Asahi Denka Kogyo
K. K and mixtures thereof
[0028] The oil-
soluble molybdenum compound may be present in an amount
sufficient to provide 0.5 ppm to 2000 ppm, 1 ppm to 700 ppm, 1 ppm to 550
ppm, 5 ppm to 300 ppm, or 20 ppm to 250 ppm of molybdenum.
Ashless Antiwear Agent
[0029] In one
embodiment the compound of Formula (1) is an ashless
antiwear agent, and it may also act as an antioxidant.
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[0030] In one embodiment the compound of Formula (1) contains an imide
group. The imide group is typically formed by taking together the Y and Y'
groups and forming a R1-N< group between two >C=0 groups.
[0031] In one embodiment the compound of Formula (1) has m, n, X, and Rl,
R2 and R6 defined as follows: m is 0 or 1, n is 1 to 2, X is >CHOR6, and Rl,
R2
and R6 are independently hydrocarbyl groups containing 4 to 30 carbon atoms.
[0032] In one embodiment Y and Y' are both -0-.
[0033] In one embodiment the compound of Formula (1) has m, n, X, Y, Y'
and Rl, R2 and R6 defined as follows: m is 0 or 1, n is 1 to 2, X is >CHOR6; Y
and Y' are both -0-, and Rl, R2 and R6 are independently hydrogen or
hydrocarbyl groups containing 4 to 30 carbon atoms.
[0034] In one embodiment the ashless antiwear agent includes imides, di-
esters, di-amides, di-imides, ester-amides, ester-imides, or imide-amides. In
one
embodiment the antiwear agent includes imides, di-esters, di-amides, or ester-
amides.
[0035] The di-esters, di-amides, ester-amide, ester-imide compounds of
Formula (1) may be prepared by reacting a dicarboxylic acid (such as tartaric
acid), with an amine or alcohol, optionally in the presence of a known
esterification catalyst. In the case of ester-imide compounds it is necessary
to
have at least three carboxylic acid groups (such as citric acid). In the ease
of a
di-in-lick, it is necessary to have at least four carboxylic acid groups The
amine
or alcohol typically has sufficient carbon atoms to fulfill the requirements
of Rl
and/or R2 as defined in Formula (1).
[0036] In one embodiment Rl and R2 are independently linear or brancht.'d
hydrocarbyl groups. In one embodiment the hydrocarbyl groups are branched.
In one embodiment the hydrocarbyl groups are linear. The Rl and R2 may be
incorporated into Formula (1) by either an amine or an alcohol. The alcohol
includes both monohydric alcohol and polyhydric alcohol. The carbon atoms of
the alcohol may be linear chains, branched chains, or mixtures thereof
[0037] Examples of a suitable branched alcohol include 2-ethylhexanol,
isotridecanol, Guerbet alcohols, or mixtures thereof
[0038] Examples of a monohydric alcohol include methanol, ethanol,
propanol,
butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol,
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dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol,
octadecanol, nonadecanol, eicosanol, or mixtures thereof In one embodiment the
monohydric alcohol contains 5 to 20 carbon atoms.
[0039] The
alcohol includes either a monohydric alcohol or a polyhydric alcohol.
Examples of a suitable polyhydric alcohol include ethylene glycol, propylene
glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,5-pentane diol, 1,6-hexane
diol, glycerol, sorbitol, pentaerythritol, trimethylolpropane, starch,
glucose,
sucrose, methylglucoside, or mixtures thereof. In one
embodiment the
polyhydric alcohol is used in a mixture along with a monohydric alcohol.
Typically, in such a combination the monohydric alcohol constitutes at least
60
mole percent, or at least 90 mole percent of the mixture.
[0040] In one
embodiment ashless antiwear agent is derived from tartaric
acid. The tartaric acid used for preparing the tartrates of the invention can
be
commercially available, and it is likely to exist in one or more isomeric
forms
such as d-tartaric acid, 1-tartaric acid or mesotartaric acid, often depending
on
the source (natural) or method of synthesis (from maleic acid). For example a
racemic mixture of d-tartaric acid and 1-tartaric acid is obtained from a
catalysed
oxidation of maleic acid with hydrogen peroxide (with tungstic acid catalyst).
These derivatives can also be prepared from functional equivalents to the
diacid
readily apparent to those skilled in the art, such as esters, acid chlorides,
or
anhydrides.
[0041] When the
compound of Formula (1) is derived from tartaric acid,
resultant tartrates may be solid, semi-solid, or oil depending on the
particular
alcohol used in preparing the tartrate. For use
as additives in a lubricating
composition the tartrates are advantageously soluble and/or stably dispersible
in
such oleaginous compositions. For example, compositions intended for use in
oils are typically oil-soluble and/or stably dispersible in an oil in which
they are
to be used. The term "oil-soluble" as used in this specification and appended
claims does not necessarily mean that all the compositions in question are
miscible or soluble in all proportions in all oils. Rather, it is intended to
mean
that the composition is soluble in an oil (mineral, synthetic, etc.) in which
it is
intended to function to an extent which permits the solution to exhibit one or
more of the desired properties.
Similarly, it is not necessary that such
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"solutions" be true solutions in the strict physical or chemical sense. They
may
instead be micro-emulsions or colloidal dispersions which, for the purpose of
this invention, exhibit properties sufficiently close to those of true
solutions to
be, for practical purposes, interchangeable with them within the context of
this
invention.
[0042] In one embodiment the ashless antiwear agent includes a compound
derived from a hydroxycarboxylic acid. In one embodiment the ashless antiwear
agent is derived from at least one of hydroxy-polycarboxylic acid di-ester, a
hydroxy-polycarboxylic acid di-amide, a hydroxy-polycarboxylic acid di-imide,
a hydroxy-polycarboxylic acid ester-amide, a hydroxy-polycarboxylic acid ester-
imide, and a hydroxy-polycarboxylic acid imide-amide. In one embodiment the
ashless antiwear agent is derived from at least one of the group consisting of
a
hydroxy-polycarboxylic acid di-ester, a hydroxy-polycarboxylic acid di-amide,
and a hydroxy-polycarboxylic acid ester-amide.
[0043] Examples of a suitable a hydroxycarboxylic acid include citric acid,
tartaric acid, lactic acid, glycolic acid, hydroxy-propionic acid,
hydroxyglutaric
acid, or mixtures thereof. In one embodiment ashless antiwear agent is derived
from tartaric acid, citric acid, hydroxy-succinic acid, dihydroxy mono-acids,
mono-hydroxy diacids, or mixtures thereof. In one embodiment the ashless
antiwear agent includes a compound derived from tartaric acid or citric acid.
In
one embodiment the ashless antiwear agent includes a compound derived from
tartaric acid. In one embodiment the compound of Formula (1) is not a citrate.
[0044] US Patent Application 2005/198894 discloses suitable
hydroxycarboxylic acid compounds, and methods of preparing the same.
[0045] Canadian Patent 1183125; US Patent Publication numbers
2006/0183647 and US-2006-0079413; International Publication number
W02008/067259;
and British Patent 2 105 743 A, all disclose examples of suitable
tartaric acid derivatives.
[0046] In one embodiment the di-esters, di-amides, di-imides, ester-amide,
ester-imide, imide-amide compounds are derived from a compound of Formula
(1). In one embodiment the di-esters, di-amides, ester-amide, compounds are
derived from a compound of Formula (1).
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[0047] A detailed description of methods for preparing suitable tartrimides
(by reacting tartaric acid with a primary amine) is disclosed in US Patent
4,237,022.
[0048] In one embodiment the ashless antiwear agent includes imide, di-
esters, di-amides, ester-amide derivatives of tartaric acid.
[0049] Examples of a suitable citric acid derivative include trialkyl
citrates or
borated trialkyl citrates. Suitable examples include triethyl citrate,
tripentyl
citrate with ethyl dipentyl citrate, borated triethyl citrate, tributyl
citrate, triethyl
citrate transesterified with 1,2-propandiol, triethyl 0-acetyl citrate,
triethyl
citrate octadecyl succinate, or mixtures thereof. A more detailed description
of
suitable citrates is disclosed in WO 2005/087904 and U.S. Patent 5,338,470.
Other suitable citrates include 2-ethylhexyl citrate, dodecyl citrate, or
mixtures
thereof.
[0050] The ashless antiwear agent of the invention, typically a tartrate,
may
also function as rust and corrosion inhibitors, friction modifiers, antiwear
agents
and demulsifiers.
[0051] In one embodiment the ashless antiwear agent is not borated.
[0052] The ashless antiwear agent of the may be present at 0.01 wt % to 20
wt %, or 0.05 to 10 wt %, or 0.1 to 5 wt % of the lubricating composition.
Oils of Lubricating Viscosity
[0053] The lubricating composition comprises an oil of lubricating
viscosity.
Such oils include natural and synthetic oils, oil derived from hydrocracking,
hydrogenation, and hydrofinishing, unrefined, refined and re-refined oils and
mixtures thereof.
[0054] Unrefined oils are those obtained directly from a natural or
synthetic
source generally without (or with little) further purification treatment.
[0055] 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. Purification techniques are known in the art and include solvent
extraction, secondary distillation, acid or base extraction, filtration,
percolation
and the like.
[0056] Re-refined oils are also known as reclaimed or reprocessed oils, and
are obtained by processes similar to those used to obtain refined oils and
often
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are additionally processed by techniques directed to removal of spent
additives
and oil breakdown products.
[0057] Natural
oils useful in making the inventive lubricants include animal
oils, vegetable oils (e.g., castor oil,), 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 and oils derived
from coal or shale or mixtures thereof.
[0058] Synthetic
lubricating oils are useful and include hydrocarbon oils such
as polymerized, oligomerised, or interpolymerised olefins (e.g.,
polybutylenes,
polypropylenes, propyleneisobutylene copolymers); poly(1-hexenes), poly(1-
octenes), trimers or oligorners of 1-deeene, e.g., poly(1-decenes), such
materials
being often referred to as poly a-olefins, and mixtures thereof; alkyl-
benzenes
(e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-
benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls);
diphenyl alkanes, alkylated diphenyl alkanes, alkylated diphenyl ethers and
alkylated diphenyl sulphides and the derivatives, analogs and homologs thereof
or mixtures thereof.
[0059] Other
synthetic lubricating oils include polyol esters (such as
Prolube03970), diesters, liquid esters of phosphorus-containing acids (e.g.,
tricresyl phosphate, trioctyl phosphate, and the diethyl ester of decane
phosphonic acid), or polymeric tetrahydrofurans. Synthetic
oils may be
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.
[0060] Oils of
lubricating viscosity may also be defined as specified in the
American Petroleum Institute (API) Base Oil Interchangeability Guidelines. The
five base oil groups are as follows: Group I (sulphur content >0.03 wt %,
and/or
<90 wt % saturates, viscosity index 80-120); Group II (sulphur content <0.03
wt
%, and >90 wt % saturates, viscosity index 80-120); Group III (sulphur content
<0.03 wt %, and >90 wt % saturates, viscosity index >120); Group IV (all
polyalphaolefins (PA0s)); and Group V (all others not included in Groups I,
II,
III, or IV). The oil of lubricating viscosity comprises an API Group I, Group
II,
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Group III, Group IV, Group V oil or mixtures thereof. Often the oil of
lubricating viscosity is an API Group I, Group II, Group III, Group IV oil or
mixtures thereof Alternatively the oil of lubricating viscosity is often an
API
Group II, Group III or Group IV oil or mixtures thereof.
[0061] The amount of the oil of lubricating viscosity present is typically
the
balance remaining after subtracting from 100 wt % the sum of the amount of the
ashless antiwear agent, the oil-soluble molybdenum compound and the other
performance additives.
[0062] The lubricating composition may be in the form of a concentrate
and/or a fully formulated lubricant. If the lubricating composition of the
invention (comprising (i) the ashless antiwear agent and (ii) the oil-soluble
molybdenum compound) is in the form of a concentrate (which may be combined
with additional oil to form, in whole or in part, a finished lubricant), the
ratio of
the of components of the invention to the oil of lubricating viscosity and/or
to
diluent oil include the ranges of 1:99 to 99:1 by weight, or 80:20 to 10:90 by
weight.
Other Performance Additives
[0063] The composition optionally comprises other performance additives.
The other performance additives comprise at least one of metal deactivators,
viscosity modifiers, detergents, friction modifiers (other than an oil-soluble
molybdenum compound or a compound of Formula (1)), antiwear agents (other
than the ashless antiwear agent of the invention), corrosion inhibitors,
dispersants, dispersant viscosity modifiers, extreme pressure agents,
antioxidants
(other than an oil-soluble molybdenum compound of the invention), foam
inhibitors, demulsifiers, pour point depressants, seal swelling agents and
mixtures thereof Typically, fully-formulated lubricating oil will contain one
or
more of these performance additives.
[0064] In one embodiment the lubricating composition comprises the ashless
antiwear agent and further comprises at least one of a viscosity modifier, an
antioxidant, an overbased detergent, a succinimide dispersant, or mixtures
thereof.
[0065] In one embodiment the lubricating composition comprising the ashless
antiwear agent further comprises a phosphorus-containing antiwear agent.
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Detergents
[0066] The
lubricant composition optionally further comprises other known
neutral or overbased detergents. Suitable detergent substrates include
phenates,
sulphur containing phenates, sulphonates, salixarates, salicylates, carboxylic
acid, phosphorus acid, mono- and/or di- thiophosphoric acid, alkyl phenol,
sulphur coupled alkyl phenol compounds, or saligenins. Various overbased
detergents and their methods of preparation are described in greater detail in
numerous patent publications, including W02004/096957 and references cited
therein. The detergent substrate is typically salted with a metal such as
calcium,
magnesium, potassium, sodium, or mixtures thereof. In one embodiment the
lubricating composition further includes an overbased detergent. Typically the
overbased detergent includes phenates, sulphur containing phenates,
sulphonates,
salixarates, salicylates, or mixtures thereof.
[0067] The
detergent may be present at 0 wt % to 10 wt %, or 0.1 wt % to 8
wt %, or 1 wt % to 4 wt %, or greater than 4 to 8 wt %.
Dispersants
[0068]
Dispersants are often known as ashless-type dispersants because, prior
to mixing in a lubricating oil composition, they do not contain ash-forming
metals and they do not normally contribute any ash forming metals when added
to a lubricant and polymeric dispersants. Ashless
type dispersants are
characterised by a polar group attached to a relatively high molecular weight
hydrocarbon chain. Typical ashless dispersants include N-substituted long
chain
alkenyl succinimides. Examples
of N-substituted long chain alkenyl
succinimides include polyisobutylene succinimide with number average
molecular weight of the polyisobutylene substituent in the range 350 to 5000,
or
500 to 3000. Succinimide dispersants and their preparation are disclosed, for
instance in US Patent 3,172,892 or US Patent 4,234,435 r in EP 0355895.
Succinimide dispersants are typically the imide formed from a polyamine,
typically a poly(ethyleneamine).
[0069] In one
embodiment the invention further comprises at least one
polyisobutylene suecinimide dispersant derived from poiyisobutylene with
number
average molecular weight in the range 350 to 5000, or 500 to 3000. The
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polyisobutylene succinimide may be used alone or in combination with other
dispersants.
[0070] In one
embodiment the invention further comprises at least one
dispersant derived from polyisobutylene succinic anhydride, an amine and zinc
oxide to form a polyisobutylene succinimide complex with zinc. The
polyisobutylene succinimide complex with zinc may be used alone or in
combination.
[0071] Another
class of ashless dispersant is Mannich bases. Mannich
dispersants are the reaction products of alkyl phenols with aldehydes
(especially
formaldehyde) and amines (especially polyalkylene polyamines). The alkyl
group typically contains at least 30 carbon atoms.
[0072] The
dispersants may also be post-treated by conventional methods by
a reaction with any of a variety of agents. Among these are boron, urea,
thiourea, dimercaptothiadiazoles, carbon disulphide, aldehydes, ketones,
carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic
anhydride,
nitriles, epoxides, and phosphorus compounds.
[0073] The
dispersant may be present at 0 wt % to 20 wt %, or 0.1 wt % to
15 wt %, or 0.1 wt % to 10 wt %, or 1 wt % to 6 wt %, or 7 wt % to 12 wt % of
the lubricating composition.
Antioxidants
[0074] Antioxidant compounds are known and include for example,
sulphurised olefins (typically sulphurised 4-carbobutoxy cyclohex,:ne, or
triphenylphosphite equivalents thereof, or olefin sulphide), alkylated
diphenylamines (e.g., nonyl diphenylamine, typically di-nonyl diphenylamine,
octyl diphenylamine, di-octyl diphenylamine), hindered phenols, or mixtures
thereof Antioxidant compounds may be used alone or in combination. The
antioxidant may be present in ranges 0 wt % to 20 wt %, or 0.1 wt % to 10 wt
%,
or 1 wt % to 5 wt %, of the lubricating composition.
[0075] The
hindered phenol antioxidant often contains a secondary butyl
and/or a tertiary butyl group as a sterically hindering group. The phenol
group is
often further substituted with a hydrocarbyl group and/or a bridging group
linking to a second aromatic group. Examples of suitable hindered phenol
antioxidants include 2,6-di-tert-butylphenol, 4-methy1-2,6-di-tert-
butylpheno1, 4-
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ethy1-2,6-di-tert-butylpheno1, 4-propy1-2,6-di-tert-butylphenol or 4-buty1-2,6-
di-
tert-butylphenol, or 4-dodecy1-2,6-di-tert-butylphenol. In one embodiment the
hindered phenol antioxidant is an ester and may include, e.g., IrganoxTM L-135
from Ciba or aî addition product derived from 2,6-di-tert-butylphenol and an
alkyl acrylate, wherein the alkyl group may contain 1 to 18, or 2 to 12, or 2
to 8,
or 2 to 6, or 4 carbon atoms. A more detailed description of suitable ester-
containing hindered phenol antioxidant chemistry is found in US Patent
6,559,105.
[0076] In one embodiment the lubricant does not contain (or contains
reduced
amounts of) phenolic antioxidant, when the compound of Formula (1) is
employed. This embodiment may be useful because the compound of Formula
(1) may be used as a partial or whole replacement for phenolic antioxidants.
It is
believed that during the preparation of tertiary butyl phenols trace amounts
of an
impurity tris-tert-butyl phenol are formed and retained in the final product.
Tris-
tert-butyl phenol is known to bioaccumulate and builds up to high
concentrations
in sediment. Thus employing the compound of Formula (1) as an antioxidant
may allow for reduction of bioaccumulants.
Viscosity Modifiers
[0077] Viscosity modifiers include hydrogenated copolymers of styrene-
butadiene, ethylene-propylene copolymers, polyisobutenes, hydrogenated
styrene-isoprene polymers, hydrogenated isoprene polymers, polymethacrylates,
polyacrylates, polyalkyl styrenes, hydrogenated alkenyl aryl conjugated diene
copolymers, polyolefins, esters of maleic anhydride-styrene copolymers, or
esters of (alpha-olefin maleic anhydride) copolymers, or mixtures thereof.
Dispersant Viscosity Modifiers
[0078] Dispersant viscosity modifiers (often referred to as DVM), include
functionalised polyolefins, for example, ethylene-propylene copolymers that
have been functionalised with the reaction product of an acylating agent (such
as
maleic anhydride) and an amine; polymethacrylates functionalised with an
amine, or esterified maleic anhydride-styrene copolymers reacted with an
amine.
[0079] The total amount of viscosity modifier and/or dispersant viscosity
modifier may be 0 wt % to 20 wt %, 0.1 wt % to 15 wt %, or 0.1 wt % to 10 wt
%, of the lubricating composition.
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Antiwear Agents
[0080] The
lubricant composition optionally further comprises at least one
other antiwear agent other than the ashless antiwear agent of the invention.
Examples of suitable antiwear agents include phosphate esters, sulphurised
olefins, sulphur-containing anti-wear additives including
metal
dihydrocarbyldithiophosphates (such as zinc dialkyldithiophosphates),
thiocarbamate-containing compounds including, thiocarbamate esters, alkylene-
coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulphides.
[0081] The
dithiocarbamate-containing compounds may be prepared by
reacting a dithiocarbamate acid or salt with an unsaturated compound. The
dithiocarbamate containing compounds may also be prepared by simultaneously
reacting an amine, carbon disulphide and an unsaturated compound. Generally,
the reaction occurs at a temperature of 25 C to 125 C. US Patents 4,758,362
and 4,997,969 describe dithiocarbamate compounds and methods of making them.
[0082] Examples
of suitable olefins that may be sulphurised to form an the
sulphurised olefin include propylene, butylene, isobutylene, pentene, hexane,
heptene, octane, nonene, decene, undecene, dodecene, undecyl, tridecene,
tetradecene, pentadecene, hexadecene, heptadecene, octadecene, octadecenene,
nonodecene, eicosene or mixtures thereof. In one embodiment, hexadecene,
heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixtures
thereof and their dimers, trimers and tetramers are especially useful olefins.
Alternatively, the olefin may be a Diels-Alder adduct of a diene such as
1,3-butadiene and an unsaturated ester, such as, butylacrylate.
[0083] Another
class of sulphurised olefin includes fatty acids and their
esters. The fatty acids are often obtained from vegetable oil or animal oil
and
typically contain 4 to 22 carbon atoms. Examples of suitable fatty acids and
their esters include triglycerides, oleic acid, linoleic acid, palmitoleic
acid or
mixtures thereof. Often, the fatty acids are obtained from lard oil, tall oil,
peanut
oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof. In
one
embodiment fatty acids and/or ester are mixed with olefins, such as u-olefins.
[0084] In an
alternative embodiment, the ashless antiwear agent (which may
also be described as a friction modifier) may be a monoester of a polyol and
an
aliphatic carboxylic acid, often an acid containing 12 to 24 carbon atoms.
Often
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the monoester of a polyol and an aliphatic carboxylic acid is in the form of a
mixture with a sunflower oil or the like, which may be present in the ashless
antiwear agent mixture include 5 to 95, or in other embodiments 10 to 90, or
20
to 85, or 20 to 80 weight percent of said mixture. The aliphatic carboxylic
acids
(especially a monocarboxylic acid) which form the esters are those acids
typically containing 12 to 24 or 14 to 20 carbon atoms. Examples of carboxylic
acids include dodecanoic acid, stearic acid, lauric acid, behenic acid, and
oleic
acid.
[0085] Polyols include diols, triols, and alcohols with higher numbers of
alcoholic OH groups. Polyhydric alcohols include ethylene glycols, including
di-, tri- and tetraethylene glycols; propylene glycols, including di-, tri-
and
tetrapropylene glycols; glycerol; butanediol; hexanediol; sorbitol; arabitol;
mannitol; sucrose; fructose; glucose; cyclohexane diol; erythritol; and
pentaerythritols, including di- and tripentaerythritol. Often the polyol is
diethyl-
ene glycol, triethylene glycol, glycerol, sorbitol, pentaerythritol or
dipentaerythritol. The commercial material known as glycerol monooleate is
believed to include about 60 + 5 percent by weight of the chemical species
"glycerol monooleate," along with 35 + 5 percent glycerol dioleate, and less
than
about 5 percent trioleate and oleic acid. The amounts of the monoesters,
described below, are the amounts of the commercial grade material.
[0086] The antiwear agent may be present in ranges including 0 wt % to 15
wt %, or 0 wt % to 10 wt %, or 0.05 wt % to 5 wt %, or 0.1 wt % to 3 wt % of
the lubricating composition.
[0087] In one embodiment the lubricating composition is free of zinc
dihydrocarbyl dithiophosphate. In one embodiment the lubricating composition
further includes zinc dihydrocarbyl dithiophosphate.
Extreme Pressure Agents
[0088] Extreme Pressure (EP) agents that are soluble in the oil include
sulphur- and chlorosulphur-containing EP agents, chlorinated hydrocarbon EP
agents and phosphorus EP agents. Examples of such EP agents include
chlorinated wax; organic sulphides and polysulphides such as
dibenzyldisulphide, bis¨(chlorobenzyl) disulphide, dibutyl tetrasulphide,
sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised
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dipentene, sulphurised terpene, and sulphurised Diels-Alder adducts;
phosphosulphurised hydrocarbons such as the reaction product of phosphorus
sulphide with turpentine or methyl oleate; phosphorus esters such as the
dihydrocarbon and trihydrocarbon phosphites, e.g., dibutyl phosphite, diheptyl
phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl
phosphite, tridecyl phosphite, distearyl phosphite and polypropylene
substituted
phenyl phosphite; metal thiocarbamates such as zinc dioctyldithiocarbamate and
barium heptylphenol diacid; amine salts of alkyl and dialkylphosphoric acids,
including, for example, the amine salt of the reaction product of a
dialkyldithiophosphoric acid with propylene oxide; and mixtures thereof.
Friction Modifiers
[0089] In one embodiment the further comprises a friction modifier, or
mixtures thereof. Typically the friction modifier may be present in ranges
including 0 wt % to 10 wt %, or 0.05 wt % to 8 wt %, or 0.1 wt % to 4 wt %.
[0090] Examples of suitable friction modifiers include long chain fatty
acid
derivatives of long chain fatty acid derivatives of amines, esters, or
epoxides;
fatty imidazolines (that is, long chain fatty amides, long chain fatty esters,
long
chain fatty epoxide derivatives, and long chain fatty imidazolines); and amine
salts of alkylphosphoric acids.
[0091] Friction modifiers may also encompass materials such as sulphurised
fatty compounds and olefins, triglycerides (e.g. sunflower oil) or monoester
of a
polyol and an aliphatic carboxylic acid (all these friction modifiers have
been
described as antioxidants or antiwear agents).
[0092] In one embodiment the friction modifier is a long chain fatty amide,
a
long chain fatty ester, a long chain fatty epoxide derivatives, or a long
chain
fatty imidazoline.
[0093] In one embodiment the friction modifier is a long chain fatty acid
ester (previously described above as an ashless antiwear agent). In another
embodiment the long chain fatty acid ester is a mono-ester and in another
embodiment the long chain fatty acid ester is a (tri)glyceride.
Other Additives
[0094] Other performance additives such as corrosion inhibitors include
those
described in paragraphs 5 to 8 of International Publication number
W02006/047486
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(McAtee and Boyer as named inventors), octylamine octanoate, and
condensation products of dodecenyl succinic acid or anhydride and a fatty acid
such as oleic acid with a polyamine. In one embodiment the corrosion
inhibitors
include the Synalox corrosion inhibitor. The Synalox corrosion inhibitor is
typically a homopolymer or copolymer of propylene oxide. The Synalox
corrosion inhibitor is described in more detail in a product brochure with
Form
No. 118-01453-0702 AMS, published by The Dow Chemical Company. The
product brochure is entitled "SYNALOX Lubricants, High-Performance
Polyglycols for Demanding Applications."
[0095] Metal deactivators including derivatives of benzotriazoles
(typically
tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazoles,
benzimidazoles,
2-alkyldithiobenzimidazoles, or 2-alkyldithiobenzothiazoles; foam inhibitors
including copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally
vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene
glycols,
polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide)
polymers; pour point depressants including esters of maleic anhydride-styrene,
polymethacrylates, polyacrylates or polyacrylamides.
Industrial Application
[0096] The lubricating composition may be utilised in a range of surfaces
typically found in mechanical devices, including aluminum-alloy surfaces. The
mechanical devices include an internal combustion engine, a gearbox, an
automatic transmission, a hydraulic or a turbine. Typically the lubricating
composition may be an engine oil, a gear oil, an automatic transmission oil, a
hydraulic fluid, a turbine oil, a metal working fluid or a circulating oil. In
one
embodiment the mechanical device is an internal combustion engine.
[0097] In one embodiment the internal combustion engine may be a diesel
fuelled engine, a gasoline fuelled engine, a natural gas fuelled engine or a
mixed
gasoline/alcohol fuelled engine. In one embodiment the internal combustion
engine may be a diesel fuelled engine and in another embodiment a gasoline
fuelled engine.
[0098] The internal combustion engine may be a 2-stroke or 4-stroke engine.
Suitable internal combustion engines include marine diesel engines, aviation
piston engines, low-load diesel engines, and automobile and truck engines.
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[0099] In one embodiment the internal combustion engine contains
components of an aluminium-alloy. The aluminium-alloy includes aluminium
silicates, aluminium oxides, or other ceramic materials. In one embodiment the
aluminium-alloy is an aluminium-silicate surface. As useci herein, the term
"aluminum alloy" is intended to be synonymous -with "aluminium composite"
and to describe a component or surface comprising aluminium and another
component intermixed or reacted on a microscopic or nearly microscopic level.,
regardless of the detailed structure thereof. This would include any
conventional
alloys with metals other than aluminium as -well as composite or alloy-like
structures with non-nietallic elements or compounds such as with ceramic-like
materials.
[01001 The lubricant composition for an internal combustion engine may be
suitable for any engine lubricant irrespective of the sulphur, phosphorus or
sulphated ash (ASTM D-874) content. The sulphur content of the engine oil
lubricant may be 1 wt % or less, or 0.8 wt % or less, or 0.5 wt % or less, or
0.3
wt % or less. In one embodiment the sulphur content may be in the range of
0.001 wt % to 0.5 wt %, or 0.01 wt % to 0.3 wt %. The phosphorus content may
be 0.2 wt % or less, or 0.1 wt % or less, or 0.085 wt % or less, or even 0.06
wt %
or less, 0.055 wt % or less, or 0.05 wt % or less. In one embodiment the
phosphorus content may be 100 ppm to 1000 ppm, or 325 ppm to 700 ppm. The
total sulphated ash content may be 2 wt % or less, or 1.5 wt % or less, or 1.1
wt
% or less, or 1 wt % or less, or 0.8 wt % or less, or 0.5 wt % or less. In one
embodiment the sulphated ash content may be 0.05 wt % to 0.9 wt %, or 0.1 wt
% or 0.2 wt % to 0.45 wt %. in another embodiment the sulphur content is 0,4
-wt (.'/.) or less, the phosphorus content is 0.08 wt % or less, and the
sulphated ash
is 1 wt A or less. in yet another embodiment the sulphur content is 0.3 wt%
or
less, the -phosphorus content is 0.05 wt % or less, and the sulphated ash is
0.8 wt
% or less,
[0101] In one embodiment the lubricating composition is an engine oil,
wherein the lubricating composition is characterised as having (i) a sulphur
content of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % or less,
and
(iii) a sulphated ash content of 1.5 wt % or less.
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[0102] In one
embodiment the lubricating composition is suitable for a 2-
stroke or a 4-stroke marine diesel internal combustion engine. In one
embodiment the marine diesel combustion engine is a 2-stroke engine. The
ashless antiwear agent of the invention may be added to a marine diesel
lubricating composition at 0.01 to 20 wt %, or 0.05 to 10 wt %, or 0.1 to 5 wt
%.
[0103] The
following examples provide illustrations of the invention. These
examples are non-exhaustive and are not intended to limit the scope of the
invention.
EXAMPLES
[0104] As used
herein all of the quantities for dispersants, detergents and
viscosity modifiers shown below include conventional amount of diluent oil
Typically the diluent oil constitutes 20 wt % to 90 wt % of each component.
For
antiwear agents, corrosion inhibitors, antioxidants the amounts shown are on
an
actives basis i.e. excluding diluent oil because the components are typically
not
carried in diluent oil.
[0105] Example 1
(EX1): A lubricating composition is prepared containing 1
wt % of di-2-ethylhexyl tartrate, 0.6 wt % of other antiwear agents, 7.9 wt %
of
dispersants, 1.5 wt % of detergents, 3.6 wt % of antioxidants including an
effective amount of molybdenum dithiocarbamate, 6.1 wt % of viscosity
modifier, 0.1 wt % of corrosion inhibitor, and 0.1 wt % of friction modifier.
The
lubricating composition has a sulphated ash content of 0.6 wt %, a phosphorus
content of about 570 ppm, and a sulphur content of 0.17 wt %.
[0106] Example 2
(EX2): A lubricating composition is prepared containing 1
wt % of a C12-14-alkyl tartrate, 4.1 wt % of dispersants, 1.4 wt % of
detergents,
2.5 wt % of antioxidants including 0.7 wt % of molybdenum dithiocarbamate
(commercially available as SakuralubeTm515, manufactured by Asahi Denka),
0.56 wt % of antiwear agents, 0.1 wt % of corrosion inhibitor, and 0.1 wt % of
friction modifier. The lubricating composition has a phosphorus content of
about 560 ppm.
[0107]
Comparative Example 1 (CE1): is similar to Example 2 except the
composition does not contain 0.7 wt % of molybdenum dithiocarbamate, nor 1
wt % of a C12-14-alkyl tartrate.
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[0108] Comparative Example 2 (CE2): is similar to Example 2 except the
composition does not contain 0.7 wt % of molybdenum dithiocarbamate.
[0109] Comparative Example 3 (CE3): is similar to Example 2 except the
composition does not contain 1 wt % of a C12-14-alkyl tartrate.
[0110] 10 g samples of the examples above are each treated with one volume
percent of cumene hydroperoxide. The samples (2 ml portions) are then
evaluated for wear performance in an isothermal temperature high frequency
reciprocating rig (HFRR) available from PCS Instruments. HFRR conditions for
the evaluations are 500g load, 75 minute duration, 1000 micrometer stroke, 20
hertz frequency, and at 105 C. Wear scar in micrometers and film formation as
percent film thickness are then measured with lower wear scar values and
higher
film formation values indicating improved wear performance. The results
obtained are:
Tartrate Examples Wear Scar (Lim) Film Thickness (%)
EX2 169 95
CE1 358 1
CE2 188 88
CE3 189 57
[0111] Overall the results indicate that the lubricating composition of the
invention is capable of providing at least one of (i) reducing or preventing
phosphorus emissions, (ii) reducing or preventing sulphur emissions, (ii)
wholly
or partially replacing ZDDP in lubricating oils, (iii) improving fuel economy,
and (iv) fuel economy retention/efficiency.
[0112] Example 3 (EX3): A lubricating composition is designed to meet Euro
4 and Euro 5 emission standards and containing 1 wt % of C8_10 alkyl tartrate.
The lubricating composition has a phosphorus content of 900 ppm or less, 0.3
wt
% or less of sulphur, and 0.0 wt % or less of sulphated ash.
[0113] Example 4 (EX4): A lubricating composition is designed to meet Euro
4 and Euro 5 emission standards and containing 1 wt % of C8_10 alkyl tartrate.
The lubricating composition has a phosphorus content of 500 ppm or less, 0.2
wt
% or less of sulphur, and 0.5 wt % or less of sulphated ash.
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[0114] Comparative Examples 4 (CE4) and 5 (CE5): are lubricating
composition similar to EX3 and EX4 respectively, except the C8-10 alkyl
tartrate
is not included.
[0115] An iron-catalysed bulk oxidation test is carried out on EX3, EX4,
CE4
and CE5. The test is run at 170 C, with an air flow of 10 litres per hour,
and in
the presence of 360 ppm of iron catalyst. Oxidation is measured by the
monitoring the peak area increase of the CO stretch from FT-IR. The results
obtained for EX4 and CE5 indicate that the relative peak area increases by 383
units for EX4. In contrast, the relative peak area increases by 428 units for
CE5.
Thus using a compound within the definition of Formula (1) of the present
invention reduces oxidation of a lubricant (especially an internal combustion
engine).
[0116] It is known that some of the materials described above may interact
in
the final formulation, so that the components of the final formulation may be
different from those that are initially added. The products formed thereby,
including the products formed upon employing lubricant composition of the
present invention in its intended use, may not be susceptible of easy
description.
Nevertheless, all such modifications and reaction products are included within
the scope of the present invention; the present invention encompasses
lubricant
composition prepared by admixing the components described above.
[0117]
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
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for each element of the invention may be used together with ranges or amounts
for any of the other elements.
[0118] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl
group" is used in its ordinary sense, which is well-known to those skilled in
the
art. Specifically, it refers to a group having a carbon atom directly attached
to
the remainder of the molecule and having predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
(i) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),
alicyclic (e.g., cyclo alkyl, cycloalkenyl) substituents, and aromatic-,
aliphatic-,
and alicyclic-substituted aromatic substituents, as well as cyclic
substituents
wherein the ring is completed through another portion of the molecule (e.g.,
two
substituents together form a ring);
(ii) substituted hydrocarbon substituents, that is, substituents containing
non-hydrocarbon groups which, in the context of this invention, do not alter
the
predominantly hydrocarbon nature of the substituent (e.g., halo (especially
chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso,
and
sulphoxy);
(iii) hetero substituents, that is, substituents which, while having a
predominantly hydrocarbon character, in the context of this invention, contain
other than carbon in a ring or chain otherwise composed of carbon atoms.
[0119] Heteroatoms include sulphur, oxygen, nitrogen, and encompass
substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more
than
two, preferably no more than one, non-hydrocarbon substituent will be present
for every ten carbon atoms in the hydrocarbyl group; typically, there will be
no
non-hydrocarbon substituents in the hydrocarbyl group.
[0120] While the invention has been explained in relation to its preferred
embodiments, it is to be understood that various modifications thereof will
become apparent to those skilled in the art upon reading the specification.
Therefore, it is to be understood that the invention disclosed herein is
intended to
cover such modifications as fall within the scope of the appended claims.
[0121] The antiwear agent described herein may be an oil-soluble derivative
of a molecule containing a first carboxy group and at least one additional
¨OH,
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-NHR, or =0 moiety separated from the carbon of said first carboxy group by a
chain of 2 or 3 atoms, where R is hydrogen or alkyl, e.g, C1-6 alkyl.
