USES AND COMPOSITIONS
This invention relates to anti-wear additives and friction modifiers and their use in
lubricant compositions and fuel compositions.
It is known to use anti-wear additives and/or friction modifiers in lubricant
compositions. It is also known to use anti-wear additives and/or friction modifiers in fuel
compositions for internal combustion engines.
The ingress of fuel and fuel additives into the crankcase lubricant of an internal
combustion engine is known, for example from paragraph 2 of the abstract of SAE paper
2001-01-1962 by C. Y. Thiel et al. "The Fuel Additive/lubricant Interactions:..."
Zinc dihydrocarbyl dithiophosphates (ZDDP) have been used as anti-wear additives
in lubricant compositions for many years. A disadvantage of these additives is that, when
used to lubricate internal composition engines, they give rise to ash which contributes to
particulate matter in the exhaust emissions from the internal combustion engines. It is
therefore desirable to reduce the amount of ash-forming additives used for lubricating
internal combustion engines. It is also desirable to reduce the amount of zinc and/or
phosphorus and/or sulphur in the exhaust emissions from internal combustion engines.
Attempts have therefore been made to provide anti-wear additives and/or friction modifiers
which contain neither zinc nor phosphorus or at least contain them in reduced amounts.
US patent US 437671 1 relates to a lubricant composition and an additive comprising
a hydroxy-substituted ester of a polycarboxylic acid and a metal dihydrocarbyl
dithiophosphate. According to US 437671 , the ester may be derived from the
esterification of a polycarboxylic acid with a glycol. It is stated that such an ester may be a
partial, di- or polyester. It is also stated that the polycarboxylic acid used in preparing the
ester may be an aliphatic saturated or unsaturated acid which will generally have a total of
about 24 to about 90 carbon atoms and about 2 to about 3 carboxylic acid groups, with at
least about 9 up to about 42 carbon atoms between the carboxylic acid groups. Particularly
desirable results are said to have been obtained with additives prepared by esterifying a
dimer of a fatty acid, particularly those containing conjugated unsaturation with a
polyhydroxy compound. US437671 1 does not describe the use of glycerides of hydroxy
polycarboxylic acids.
British patent application publication GB-2097813-A relates to fuel economy
promoting lubricating oil compositions which comprise an oil of lubricating viscosity and,
as the fuel economy additive, from 0.05 to 0.2 weight percent of a glycerol partial ester of
a C16 - Ci8 fatty acid. The composition is illustrated with glycerol monooleate and
glycerol dioleate. GB-2097813-A does not describe the use of glycerides of hydroxy
polycarboxylic acids.
European patent application publication EP-0092946-A2 relates to glycerol esters
with oil-soluble copper compounds as fuel economy additives for lubricant compositions.
The preferred ester is said to be a glycerol mono- or di-ester of a saturated or unsaturated
i - C fatty acid. EP-0092946-A2 does not describe the use of glycerides of hydroxy
polycarboxylic acids.
International patent application publication WO 93/21288 relates to a lubricant
composition containing mixed friction modifiers being a combination of poly fatty acid
ester and an alkoxylated hydrocarbylamine. The lubricant compositions are said to exhibit
enhanced fuel economy. The esters are said to be one or a mixture of esters of a fatty acid
having the formula 3:
O
(CHs - C O d - R
(OH)e
wherein R represents an alkylene or alkenylene hydrocarbyl radical having from 10 to 18
carbon atoms, R8 is the residuum of a polyhydric alcohol containing from 2 to 5 carbon
atoms and from 2 to 4 hydroxyl groups, e is 0 or 1 and d is an integer of 1, 2 or 3. In more
preferred embodiments R7 is said to be an alkylene radical containing 14 to 16 carbon
atoms, R is the residuum of glycerol, e is 0 and d is 1 or 2. The acid(s) of the esters
according to formula 3 are monocarboxylic acids.
US patent US 5338470 relates to alkylated citric acid adducts as antiwear and friction
modifying additives for fuels and lubricant compositions. The alkylated citric acid adducts
are said to be formed by the reaction of citric acid with alkyl alcohols and amines. The
reaction is described using nXRy where R is said to be Ci-20 0 hydrocarbyl or
hydrocarbylene or a mixture thereof, and may optionally contain oxygen, nitrogen or
sulphur. "X" is said to be an amine, alcohol, thiol or a metal amide, alkoxide or thiolate.
The metal is said to be preferably sodium, potassium or calcium and "n" is a number from
0.2 -5.0. Such additives are illustrated only by the reaction of citric acid and oleyl alcohol.
International patent application publication WO 2005/087904 corresponding to US
2005/0198894 relates to lubricant and fuel compositions containing hydroxy carboxylic
acid and hydroxy polycarboxylic acid esters represented by the generic formula:
wherein R3 is selected from the group consisting of C -Ci linear or branched alkyl, Ci-Cis
linear or branched alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, and benzyl; and X- is selected
from a range of structures defined therein. Preferred esters are said to include citrates,
tartrates, malates, lactates, mandelates, glycolates, hydroxy propionates, hydroxyglutarates,
salicylates and the like. Trialkyl citrates and borated trialkyl citrates are said to be
especially preferred, particularly triethyl citrate and borated triethyl citrate. A particularly
preferred class of additives is said to be one wherein R 3 is a linear or branched alkyl chain
of 1 to 5 carbon atoms, e.g., methyl, ethyl, propyl, butyl, pentyl, isomers of the foregoing,
and mixtures thereof. WO 2005/087904 does not describe the use of glycerides of
hydroxy polycarboxylic acids.
International patent application publication WO 2008/067259 relates to a lowsulphur,
low-phosphorus, low ash lubricant composition suitable for lubricating an internal
combustion engine comprising an oil of lubricating viscosity and a condensation product
an alcohol of 6 to 12 carbon atoms and a material represented by the formula:
wherein each R is independently H or a hydrocarbyl group, or wherein the R groups
together form a ring; and wherein if R is H, the condensation product is optionally further
functionalised by acylation or reaction with a boron compound. According to WO
2008/067259 the alcohols useful for preparing the tartrates can contain 6 to 12, or 6 to 10,
or 8 to 0 carbon atoms, they may be linear or branched, and, if branched, the branching
may occur at any point in the chain and the branching may be of any length. WO
2008/067259 does not describe the use of glycerides of hydroxy polycarboxylic acids.
International patent application publication WO 2008/124191 relates to the use of
one or more oil-soluble fatty acid esters of a polyol in a lubricating oil composition having
a base oil comprising a major amount of a gas-to-liquid (GTL) derived base oil. Polyols
are said to include diols, triols and the like. It is stated therein that the esters of the polyols
are those of carboxylic acids having 12 to 24 carbon atoms According to WO
2008/124191 preferably the fatty acid ester is a fatty acid ester of glycerol, more
preferably, a monoester of glycerol and most preferably, the ester is glycerol
monooctadecanoate. WO 2008/124191 does not describe the use of glycerides of hydroxy
polycarboxylic acids.
International patent application publication WO 2008/147701 relates to a lubricating
composition suitable for lubricating an aluminium alloy or aluminium composite surface
comprising an oil of lubricating viscosity and an ashless antiwear agent which in one
embodiment is said to include a compound derived from a hydroxycarboxylic acid.
According to WO 2008/147701 in one embodiment the ashless antiwear agent is said to be
derived from at least one of a hydroxy-carboxylic acid di-ester, a hydroxy-carboxylic acid
di-amide, a hydroxy-carboxylic acid di-imide, a hydroxy-carboxylic acid ester-amide, a
hydroxy-carboxylic acid ester-imide and a hydroxy-carboxylic acid imide-amide.
Examples of suitable hydroxy-carboxylic acids are said to include citric acid, tartaric acid,
malic acid, lactic acid, oxalic acid, glycolic acid, hydroxy-propionic acid, hydroxyglutaric
acid or mixtures thereof. According to WO 2008/147701 the ashless antiwear agent is
represented by a compound of Formula (la) and/or (lb) defined therein. It is stated therein
that the di-esters, di-amides, di-imides, ester-amide, ester-imide, imide-amide compounds
of formula (la) and/or (lb) 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. Derivatives of hydroxycarboxylic acids are said to include imides, di-esters, diamides,
di-imides (applicable for tetra-acids and higher), ester-amides, ester-imides
(applicable for tri-acids and higher, such as citric acid), and imide-amides (applicable for
tri-acids and higher, such as citric acid). Examples of suitable branched alcohol are said to
include 2-ethylhexanol, isotridecanol, Guerbet alcohols or mixtures thereof. Examples of
monohydric alcohols are said to include methanol, ethanol, propanol, butanol, pentanol,
hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol,
tetradecanol, pentadecanol, hexadecanal, heptadecanol, octadecanol, nonadecanol,
eicosanol or mixtures thereof. It is also stated that the alcohol includes either a
monohydric alcohol or a polyhydric alcohol. Examples of suitable polyhydric alcohols are
said to include ethylene glycol, propylene glycol, 1,3-butylene glycol, 2,3-butylene glycol,
1,5-pentane diol, ,6-hexanediol, glycerol, sorbitol, pentaerythritol, trimethylolpropane,
starch, glucose, sucrose, methylglucoside or mixtures thereof. It is also stated in WO
2008/147701 that in one embodiment the polyhydric alcohol is used in a mixture along
with a monohydric alcohol. It is stated that typically, in such a combination the
monohydric alcohol constitutes at least 60 mole percent, or at least 90 mole percent of the
mixture. Di-2-ethylhexyl tartrate is the only ashless anti-wear agent illustrated in the
examples.
International patent application publication WO 2009/101276 relates to a lubricant
composition for a four stroke engine with low ash content which is said to comprise
amongst other components, at least one hydroxylated ester of the formula
R(OH)m,(COOR'(OH) p)n in which m is an integer from 0 to 8, preferably from 1 to 4, n is
an integer from 1 to 8, preferably from 1to 4, and p is an integer from 0 to 8, preferably
from 1 to 4, wherein the sum p+m is strictly higher than zero, R and R' independently
represent a linear or branched, saturated or unsaturated hydrocarbon group optionally
substituted by one or more aromatic groups and including from 1 to 30 carbon atoms, or
the borate derivatives thereof. It is stated that the hydroxylated esters may be chosen from
the monoesters or the diesters obtained from glycerol such as glycerol monooleate,
glycerol stearate or isostearate and their borated derivatives. It is also stated that the
hydroxylated esters may be chosen from the citrates, tartrates, malates, lactates,
mandelates, glycolates, hydroxypropionates, hydroxyglutarates or their borated derivatives.
The composition is illustrated only with triethyl citrate and glycerol monostearate. In
Table 3 of WO 2009/1 01276, the Cameron Plint fuel economy for a lubricant composition
(B') comprising 0.99% triethylcitrate is stated to be 2.02% compared to 1.75% for the
lubricant (A' ) without the triethylcitrate. In Table 5 ofWO 2009/101276 the Cameron
Plint fuel economy for a lubricant composition (H) comprising 1.00% triethylcitrate is
stated to be 2.04% and the M FE fuel economy to be 2.50%, whereas the
corresponding data for lubricant F without the triethyl citrate are stated to be 1.78% and
1.90% respectively.
There remains a need for alternative compositions exhibiting anti-wear and/or
friction modifier properties for example for use in non-aqueous lubricant compositions
and/or for use in internal combustion engine fuel compositions.
Thus, according to the present invention there is provided a non-aqueous lubricant
composition comprising a major amount of an oil of lubricating viscosity and a minor
amount of at least one additive which is an oil-soluble mono-, di-, or tri-glyceride of at
least one hydroxy polycarboxylic acid, or a derivative thereof and more than one other
lubricant additive.
Suitably, the lubricant composition may be used to lubricate an internal combustion
engine, for example as a crankcase lubricant.
Also according to the present invention, there is provided a method of lubricating an
internal combustion engine which method comprises supplying to the engine an oil of
lubricating viscosity and at least one additive which is an oil-soluble mono-, di-, or triglyceride
of at least one hydroxy polycarboxylic acid, or a derivative thereof. Suitably, the
internal engine is lubricated with a lubricant composition of the present invention, for
example as a crankcase lubricant. Additionally or alternatively, the glyceride may be
provided in a liquid fuel composition used to operate the internal combustion engine, at
least a portion of the glyceride ingressing into the oil composition during operation of the
engine.
Also according to the present invention there is provided a method of improving the
antiwear and/or friction properties of an oil of lubricating viscosity which method
comprises admixing said oil with an effective amount of at least one additive which is an
oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid or a
derivative thereof.
Also according to the present invention there is provided a method of preparing a
non-aqueous lubricant composition which method comprises admixing an oil of lubricating
viscosity with an effective amount of at least one additive which is an oil-soluble mono-,
di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof
together with more than one other lubricant additive.
Also according to the present invention there is provided an additive concentrate for a
non-aqueous lubricant composition comprising at least one additive which is an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof and more than one other lubricant additive. The additive concentrate may be used
in the method of improving the antiwear and/or friction properties of an oil of lubricating
viscosity according to the present invention. The additive concentrate may be used in the
method of preparing a lubricant composition according to the present invention.
According to a further embodiment of the present invention, there is provided a fuel
composition for an internal combustion engine which composition comprises a major
amount of a liquid fuel and a minor amount of at least one additive which is an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof at a concentration of up to 500 ppm by weight.
Also according to the present invention there is provided a method of improving the
antiwear and/or friction properties of a liquid fuel, which method comprises admixing said
liquid fuel with an effective amount of at least one additive which is an oil-soluble mono-,
di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof and
optionally at least one other fuel additive.
Also according to the present invention there is provided a method of preparing a
fuel composition for an internal combustion engine, which method comprises admixing a
liquid fuel with an effective amount of at least one additive which is an oil-soluble mono-,
di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof at a
concentration of up to 500 ppm by weight.
Also according to the present invention there is provided an additive concentrate for a
fuel composition for an internal combustion engine, which composition comprises at least
one additive which is an oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof and more than one other fuel additive. The
additive concentrate may be used in the method of improving the antiwear and/or friction
properties of a liquid fuel according to the present invention. The additive concentrate
may be used in the method of preparing a fuel composition according to the present
invention.
According to yet a further aspect of the present invention there is provide a method of
operating an internal combustion engine which method comprises supplying to the engine
a liquid fuel, an oil of lubricating viscosity and at least one additive which is an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof, the glyceride additive being supplied in admixture with the liquid fuel and/or the
oil of lubricating viscosity.
The present invention solves the technical problem defined above by the use as an
anti-wear additive and/or friction modifier of an oil-soluble mono-, di-, or tri-glyceride of
at least one hydroxy polycarboxylic acid, or a derivative thereof. The use may be in any of
the embodiments of the present invention including: the non-aqueous lubricant
composition, the method of lubricating an internal combustion engine, the method of
improving the antiwear and/or friction properties of an oil of lubricating viscosity, the
method of preparing a non-aqueous lubricant composition, the additive concentrate for a
non-aqueous lubricant composition, the fuel composition (for example for an internal
combustion engine), the method of improving the antiwear and or friction properties of a
liquid fuel, the method of preparing a fuel composition for an internal combustion engine,
the additive concentrate for a fuel composition for an internal combustion engine and the
method of operating an internal combustion engine.
In a particular aspect, the present invention provides the use of an oil-soluble mono-,
di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof, as
an anti-wear additive and/or friction modifier in a non-aqueous lubricant composition
and/or in a fuel composition.
Preferably, the hydroxy polycarboxylic acid has at least one hydroxy group or
derivative (for example ether or ester) thereof, which is in an alpha position with respect to
a carboxylic moiety.
Each hydroxy polycarboxylic acid may independently have from 4 to 22 carbon
atoms, for example 4 to 15 carbon atoms. The oil-soluble mono-, di-, or tri-glyceride of at
least one hydroxy polycarboxylic acid or derivative thereof may suitably have from 16 to
80 carbon atoms. The number of carbon atoms in the glyceride may affect its solubility in
oil of lubricating viscosity and/or in liquid fuel.
By oil-soluble is meant that the glyceride is soluble in an oil of lubricating viscosity
and/or a liquid fuel suitably in a friction modifying and/or antiwear improving amount for
example in an amount by weight of at least 200 pp in an oil of lubricating viscosity
and/or in an amount by weight of at least 10 ppm in a liquid fuel. The solubility may be
determined at ambient temperature, for example at 20 °C. The solubility may be
determined at atmospheric pressure.
Suitable hydroxy polycarboxylic acids include:
o citric acid (also sometimes called 3-carboxy-3-hydroxy pentanedioic acid; 2-
hydroxypropane- 1,2,3- tricarboxylic acid; or 3-hydroxypentanedioic acid-3-
carboxylic acid);
o tartaric acid (also sometimes called 2,3-dihydroxybutanedioic acid; or 2,3-
dihydroxysuccinic acid);
o malic acid (also sometimes called hydroxybutanedioic acid);
o monohydroxy trimesic acid; and
o hydrogenated monohydroxy trimesic acid (sometimes also called 1,3,5 tricarboxy, 2-
hydroxy cyclohexane).
The oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic
acid, or a derivative thereof may be a di-, or tri-glyceride which is a glyceride of at least
one hydroxy polycarboxylic acid and at least one second carboxylic acid which is a
saturated, mono-unsaturated or poly-unsaturated, branched or linear, monocarboxylic or
polycarboxylic acid having 4 to 22 carbon atoms, or a derivative thereof.
The second carboxylic acid may be saturated, mono-unsaturated or poly-unsaturated.
Suitably, the second carboxylic acid is unsaturated. The second carboxylic acid may be
branched or linear. The second carboxylic acid may be monocarboxylic or polycarboxylic
acid. If the second carboxylic acid is a polycarboxylic acid, the derivative of the glyceride
may be an ester of the second carboxylic acid group.
Suitable saturated second carboxylic acids include caproic acid, caprylic acid, capric
acid, lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid. Suitable
unsaturated second carboxylic acids include oleic acid, linoleic acid, linolenic acid,
myristoleic acid, palmitoleic acid, sapienic acid, erucic acid (also known as c -13-
docosenoic acid) and brassidic acid.
Preferably, the glyceride is a glyceride of citric acid and oleic acid, a glyceride of
citric acid and linoleic acid or a mixture thereof.
The mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid or
derivative thereof may be represented by the general formula (I):
OR'
wherein RO OR' and OR" independently represent:
-OH;
a saturated, mono-unsaturated or poly-unsaturated, branched or linear,
monocarboxylic or polycarboxylic group having from 4 to 22 carbon atoms or an
ether or an ester thereof;
a hydroxy polycarboxylic acid moiety or an ether and/or ester thereof
provided that at least one of RO, OR' and OR" is a hydroxy polycarboxylic acid moiety or
an ether and/or ester thereof.
Preferably, in formula (I) at least one of RO, OR' and OR" is a hydroxy
polycarboxylic acid moiety or an ether and/or ester thereof and at least one of RO, OR' and
OR" is a saturated, mono-unsaturated or poly-unsaturated, branched or linear,
monocarboxylic or polycarboxylic group having from 4 to 22 carbon atoms or an ester
thereof.
Preferably in formula (I), the hydroxy polycarboxylic moiety acid has at least one
hydroxy group or derivative (for example ether or ester) thereof which is in an alpha
position with respect to a carboxylic moiety.
In formula (I), each hydroxy polycarboxylic moiety may independently have from 4
to 22 carbon atoms. In formula (I) the hydroxy polycarboxylic moiety may be derivable
from acids including for example citric acid, tartaric acid, malic acid, monohydroxy
trimesic acid and hydrogenated monohydroxy trimesic acid.
In formula (I) when present, each saturated, branched or linear, monocarboxylic or
polycarboxylic group having from 4 to 22 carbon atoms or an ester thereof may be
derivable from saturated carboxylic acids or their halide equivalents. Suitable saturated
carboxylic acids include for example, caproic acid, caprylic acid, capric acid, lauric acid,
myristic acid, palmitic acid, stearic acid and arachidic acid. In formula (I) when present,
each mono-unsaturated or poly-unsaturated, branched or linear, monocarboxylic or
polycarboxylic group having from 4 to 22 carbon atoms or an ester thereof may be
derivable from unsaturated carboxylic acids or their halide equivalents. Suitable monounsaturated
acids include for example, oleic acid, myristoleic acid, palmitoleic acid,
sapienic acid, erucic acid and brassidic acid. Suitable polyunsaturated acids include for
example linoleic acid and linolenic acid,
The glyceride may be a glyceride of at least one hydroxy polycarboxylic acid and a
saturated C to C22 polycarboxylic acid, or a derivative thereof. The polycarboxylic acid
may be branched or linear. The glyceride may be a glyceride of at least one hydroxy
polycarboxylic acid and a mono-unsaturated or polyunsaturated C4 to C22 polycarboxylic
acid, or a derivative thereof. The polycarboxylic acid may be branched or linear. The
glyceride may be a glyceride of at least one hydroxy polycarboxylic acid and a saturated
C4 to C22 monocarboxylic acid, or a derivative thereof. The monocarboxylic acid may be
branched or linear. Suitable saturated C 6 monocarboxylic acids include palmitic acid.
Suitable saturated C 8 monocarboxylic acids include stearic acid. The glyceride may be a
glyceride of at least one hydroxy polycarboxylic acid and a mono-unsaturated or
polyunsaturated C4 to C22 monocarboxylic acid, or a derivative thereof. The unsaturated
monocarboxylic acid may be branched or linear. The glyceride may be a glyceride of at
least one hydroxy polycarboxylic acid and an unsaturated C1 monocarboxylic acid, or a
derivative thereof. The monocarboxylic acid may be branched or linear. Suitable hydroxy
polycarboxylic acids include citric acid. The glyceride additive may be a glyceride of
citric acid and an unsaturated C1 monocarboxylic acid, or a derivative thereof. Suitable
unsaturated C monocarboxylic acids include oleic acid and linoleic acid.
The glyceride may be a citric acid ester of a mono-glyceride of a saturated, monounsaturated
or polyunsaturated, branched or linear, monocarboxylic or polycarboxylic C4
to C22 carboxylic acid, suitably a C 6 or Ci carboxylic acid for example, palmitic acid,
stearic acid, oleic acid or linoleic acid. The glyceride may be a citric acid ester of monoglyceride
made from vegetable oil, for example sunflower and/or palm oil. The glyceride
may be a citric acid ester of mono-glyceride made from edible, refined sunflower and palm
based oil. Preferably, the glyceride is a glyceride of citric acid and oleic acid, a glyceride
of citric acid and linoleic acid or a mixture thereof. A suitable source of glycerides of
citric acid with oleic acid and/or linoleic acid is GRINSTED CITREM SP70 (Trade Mark)
which is available from Danisco. GRINSTED CITREM SP70 is believed to be a citric
acid ester of mono-glyceride made from edible, refined sunflower and palm based oil.
GRINSTED CITREM SP70 is also believed to comprise at least one diglyceride having
the structural formula (II):
O OH O COOH
CH3-Y-C
II
- O-CH2- C
I
H-CH 2-0-C
II
-CH 2- C
I
-CH2-COOH
OH
wherein -Y- represents a C1 hydrocarbyl moiety which is mono- or di-unsaturated.
Thus, diglycerides having structural formula (II) include a glyceride of citric acid and
oleic acid and a glyceride of citric acid and linoleic acid. This corresponds to a structure of
formula (I) in which (i) RO represents a carboxyl group having 18 carbon atoms, which
may be derivable from oleic acid and/or linoleic acid, (ii) OR' represents a hydroxyl
moiety, and (iii) OR' ' represents a hydroxy polycarboxylic acid moiety, which may be
derivable from citric acid.
GRINSTED® CITREM N 12 VEG from Danisco is believed to be a neutralised citric
acid ester of mono-glyceride made from edible, fully hydrogenated palm based oil. It was
found to be unsuitable because it was not oil soluble.
The use of GRINSTED CITREM 2-IN-l from Danisco as a carboxylic acid anionic
surfactant is described in paragraphs [0167] to [0171] of US patent application publication
US 2008/0176778. US 2008/0176778 relates to conveyor lubricants including emulsion of
a lipophilic compound and an emulsifier and or an anionic surfactant (title). The lipophilic
compound is said to include water insoluble organic compounds including two or more
ester linkages and in one embodiment is said to be a water insoluble organic compound
including three or more oxygen atoms. It is stated that in one embodiment, the lipophilic
compound is an ester including a di-, tri-, or poly-hydric alcohol, such as glycerol, with 2
or more of the hydroxyl groups each being coupled to a carboxylic acid as an ester group
(para. [0033]). In the example at para. [0167] to [0171] two triglyceride lubricant
compositions were tested. Lubricant A was said to contain an emulsion of 10 wt% of a
caprylate, caprate, cocoate triglyceride in water to which was added the anionic surfactant
1.5 wt% lecithin (sold under the trade name Terradrill V408, Cognis) and the emulsifier
1.5 wt% 20 mol ethoxysorbitan monostearate (sold under the trade name Tween 60V, ICI).
Lubricant B was said to contain 1.5 wt citrate ester, said to be a carboxylic acid anionic
surfactant sold under the name GRINSTED® CITREM 2-IN-l, Danisco in place of the
Terradrill V408. According to para. [0171], Triglyceride lubricants including anionic
surfactant worked well as dry conveyor lubricants and effectively lubricated after water
was applied to the conveyor. According to para. [0061] of US 2008/0176778 the
composition therein can include any variety of anionic surfactants that are effective to
increase the ability of the lipophilic emulsion to withstand application of water to the
conveyor. Examples are given in para [0065] to [0075] of ten classes of anionic surfactant.
According to para [0029] of US patent application publication US 2009/0152502,
hydrophilic emulsifier CITREM is a composition of matter containing citric esters of
mono- and diglycerides of edible fatty acids. It is also stated therein that edible fatty acids
have, in particular, 6 to 24 carbon atoms.
The glyceride may be an ester of citric acid with a partial glyceride, for example
mono- or di- glyceride or mixtures thereof, which have free hydroxyl groups. Suitable
partial glycerides include those derived from fatty acids with 12 to 18 carbon atoms,
including for example those derived from coconut oil fatty acids and palm oil fatty acids.
Examples include Lamegin® ZE 306, Lamegin® ZE 609 and Lamegin® ZE 618 (Cognis
Deutschland GmbH & Co. KG). Thus the glyceride may be a citric acid ester of the
monoglyceride of hydrogenated tallow fatty acid, for example Lamegin ZE 309, or an
ester of diacetyl tartaric acid with monoglyceride of hydrogenated tallow fatty aci , for
example Lamegin® DW 8000, or citric acid ester based on sunflower oil fatty acid
monoglyceride, for example Lamegin® ZE 609 FL. Such esters are described for example
in US 5770185 and US 2010/0087319.
The derivative of the glyceride may be an ester of the at least one hydroxy
polycarboxylic acid moiety. The ester may be an ester of a carboxylic acid moiety of the
hydroxy polycarboxylic acid. Each carboxylic acid moiety of the hydroxyl polycarboxylic
acid may be independently derivatisable as an ester. The ester derivative may be a
hydrocarbyl ester, in which the hydrocarbyl moiety may have from 4 to 22 carbon atoms.
The hydrocarbyl moiety may be an alkyl moiety which may have from 4 to 22 carbon
atoms. The hydrocarbyl moiety may comprise one or more hetero atoms for example
nitrogen and/or oxygen.
The derivative of the glyceride may be an ether or an ester of the hydroxyl moiety of
the hydroxy polycarboxylic acid. If more than one hydroxy moiety is present in the mono-
, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, each hydroxyl moiety
may independently be derivatisable as an ether or an ester. Each ether may be a
hydrocarbyl ether. The hydrocarbyl moiety of each ether may independently have from 1
to 22 carbon atoms, more suitably from 1 to 18 carbon atoms. The hydrocarbyl moiety of
each ether may independently be an alkyl moiety. The alkyl moiety of each ether may
independently have from 1to 22 carbon atoms, more suitably from 1 to 18 carbon atoms.
The hydrocarbyl moiety of each ether may independently comprise one or more hetero
atoms for example nitrogen and/or oxygen. Each ester may independently be a hydrocarbyl
ester. The hydrocarbyl moiety of each ester may have from 4 to 22 carbon atoms. The
hydrocarbyl moiety of each ester may independently be an alkyl moiety. The alkyl moiety
of each ester may independently have from 4 to 22 carbon atoms. The hydrocarbyl moiety
of each ester may independently comprise one or more hetero atoms for example nitrogen
and/or oxygen.
If the saturated, mono-unsaturated or polyunsaturated, branched or linear carboxylic
acid having 4 to 22 carbon atoms is a polycarboxylic acid, the derivative of the glyceride
may be an ester of a carboxylic acid moiety of one or more of the at least one saturated,
mono-unsaturated or poly-unsaturated, branched or linear, polycarboxylic acid having
from 4 to 22 carbon atoms, if present. Each ester may independently be a hydrocarbyl
ester. The hydrocarbyl moiety of each ester may independently have from 4 to 22 carbon
atoms. The hydrocarbyl moiety may be an alkyl moiety. The alkyl moiety of each ester
may independently have from 4 to 22 carbon atoms. The hydrocarbyl moiety of each ester
may independently comprise one or more hetero atoms for example nitrogen and/or
oxygen.
The oil-soluble mono-, di-, or tri-glycerides of at least one hydroxy polycarboxylic
acid and derivatives thereof may be made by methods known in the art. The di- and tri¬
glycerides may be made by partial hydrolysis of a fat to produce a mono-glyceride
followed by esterification with a hydroxy polycarboxylic acid. The mono-glycerides may
be made by esterification of glycerol with a hydroxy polycarboxylic acid. Hydrocarbyl
ether derivatives may be made from corresponding hydrocarbyl halides.
The oil-soluble mono-, di-, or tri-glycerides of at least one hydroxy polycarboxylic
acid and derivatives thereof have an advantage that they do not contain zinc or
molybdenum, that is, they are molybdenum-free and zinc-free. They also have an
advantage that they are sulphur-free and phosphorus-free. Generally, the additives
according to the present invention will have low volatility.
Some advantages of GRINSTED CITREM SP70 (Trade Mark) are that it has low
volatility and has low toxicity.
Lubricant Compositions and Additive Concentrates for Lubricant Compositions.
The amount of oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof in the lubricant composition may be in the
range of 0.02 % to 5% by weight, preferably in the range of 0.1 to 2.5 % by weight.
The non-aqueous lubricant composition is not an emulsion.
The concentration of oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof in the additive concentrate may be an amount
suitable to provide the required concentration when used in the lubricant composition. The
additive concentrate may be used in a lubricant composition in an amount of 0.5 to 20 %
by weight. Therefore, the amount of oil-soluble mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof additive and any other additives in the
lubricant concentrate may be more concentrated than that in the lubricant composition, for
example by a factor of from 1:0.005 to 1:0.20.
The lubricant composition comprises a major amount of oil of lubricating viscosity
and a minor amount of at least one additive. Major amount means greater than 50% and
minor amount means less than 50 % by weight.
The lubricant composition and the oil of lubricating viscosity may comprise base oil.
Base oil comprises at least one base stock. The oil of lubricating composition may
comprise one or more additives other than the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid. Suitably, the lubricant composition and/or the oil of
lubricating viscosity comprises base oil in an amount of from greater than 50 % to about
99.5 % by weight, for example from about 85% to about 95% by weight.
The base stocks may be defined as Group I, II, III, IV and V base stocks according to
API standard 1509, "ENGINE OIL LICENSING AND CERTIFICATION SYSTEM",
April 2007 version 16th edition Appendix E, as set out in Table 1.
Group I, Group II and Group III base stocks may be derived from mineral oils Group
I base stocks are typically manufactured by known processes comprising solvent extraction
and solvent dewaxing, or solvent extraction and catalytic dewaxing. Group II and Group
III base stocks are typically manufactured by known processes comprising catalytic
hydrogenation and/or catalytic hydrocracking, and catalytic hydroisomerisation. A suitable
Group I base stock is AP/E core 150, available from ExxonMobil. Suitable Group II
basestocks are EHC 50 and EHC 110, available from ExxonMobil. Suitable group III base
stocks include Yubase 4 and Yubase 6 available for example, from SK Lubricants. Suitable
Group V base stocks are ester base stocks, for example Priolube 3970, available from
Croda International pic. Suitable Group IV base stocks include hydrogenated oligomers of
alpha olefins. Suitably, the oligomers may be made by free radical processes, Zeigler
catalysis or by cationic Friedel-Crafts catalysis. Polyalpha olefin base stocks may be
derived from C8, CIO, C12, C14 olefins and mixtures of one or more thereof.
Table 1
The lubricant composition and the oil of lubricating viscosity may comprise one or
more base oil and/or base stock which is/are natural oil, mineral oil (sometimes called
petroleum-derived oil or petroleum-derived mineral oil), non-mineral oil and mixtures
thereof. Natural oils include animal oils, fish oils, and vegetable oils. Mineral oils include
paraffinic oils, naphthenic oils and paraffinic-naphthenic oils. Mineral oils may also
include oi s derived from coal or shale.
Suitable base oils and base stocks oils may be derived from processes such as
chemical combination of simpler or smaller molecules into larger or more complex
molecules (for example polymerisation, oligomerisation, condensation, alkylation,
acylation).
Suitable base stocks and base oils may be derived from gas-to-liquids materials, coalto-
liquids materials, biomass-to-liquids materials and combinations thereof.
Gas-to-liquids (sometimes also referred to as GTL materials) may be obtained by one
or more process steps of synthesis, combination, transformation, rearrangement,
degradation and combinations of two or more thereof applied to gaseous carbon-containing
compounds. GTL derived base stocks and base oils may be obtained from the Fischer-
Tropsch synthesis process in which synthesis gas comprising a mixture of hydrogen and
carbon monoxide is catalytically converted to hydrocarbons, usually waxy hydrocarbons
that are generally converted to lower-boiling materials hydroisomerisation and/or
dewaxing (see for example, WO 2008/124191).
Biomass-to-liquids (sometimes also referred to as BTL materials) may be
manufactured from compounds of plant origin for example by hydrogenation of carboxylic
acids or triglycerides to produce linear paraffins, followed by hydroisomerisation to
produced branched paraffins (see for example, WO-2007-068799-A).
Coal-to-liquids materials may be made by gasifying coal to make synthesis gas which
is then converted to hydrocarbons.
The base oil and/or oil of lubricating viscosity may have a kinematic viscosity at 100
°C in the range of 2 to 100 cSt, suitably in the range of 3 to 50 cSt and more suitably in the
range 3.5 to 25 cSt.
The lubricant composition of the present invention may be a multi-grade lubricating
oil composition according to the API classification xW-y where x is 0, 5, 10, 15 or 20 and
y is 20, 30, 40, 50 or 60 as defined by SAE J300 2004, for example 5W-20, 5W-30, 0W-
20. The lubricant composition may have an HTHS viscosity at 150 °C of at least 2.6cP, for
example as measured according to ASTM D4683, CEC L-36-A-90 or ASTM D5481 .
The lubricant composition may have an HTHS viscosity at 150 °C according to
ASTM D4683 of from 1 to < 2.6cP, for example about 1.8 cP.
The lubricant composition may be prepared by admixing an oil of lubricating
viscosity with an effective amount of at least one additive which is an oil-soluble mono-,
di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof
together with more than one other lubricant additive.
The method of preparing a lubricant composition and the method of improving the
antiwear and/or friction properties of an oil of lubricating viscosity comprise admixing an
oil of lubricating viscosity with an effective amount of at least one additive which is an oilsoluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof.
The oil of lubricating viscosity may be admixed with at least one additive in one or
more steps by methods known in the art. The additives may be admixed as one or more
additive concentrates or part additive package concentrates, optionally comprising solvent
or diluent. The oil of lubricating viscosity may be prepared by admixing in one or more
steps by methods known in the art, one or more base oils and/or base stocks optionally
with one or more additives and/or part additive package concentrates. The additives,
additive concentrates and/or part additive package concentrates may be admixed with oil of
lubricating viscosity or components thereof in one or more steps by methods known in the
art.
Other Anti-wear Additives
The lubricant composition and the additive concentrate for a lubricant composition
may further comprise at least one anti-wear additive other than the additive which is an oilsoluble
mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof. Such other anti-wear additives may be ash-producing additives or
ashless additives. Examples of such other anti-wear additives include non-phosphorus
containing additives for example, sulphurised olefins. Examples of such other anti-wear
additives also include phosphorus-containing antiwear additives. Examples of suitable
ashless phosphorus-containing anti-wear additives include trilauryl phosphite and
triphenylphosphorothionate and those disclosed in paragraph [0036] of US2005/01 98894.
Examples of suitable ash-forming, phosphorus-containing anti-wear additives include
dihydrocarbyl dithiophosphate metal salts. Examples of suitable metals of the
dihydrocarbyl dithiophosphate metal salts include alkali and alkaline earth metals,
aluminium, lead, tin, molybdenum, manganese, nickel, copper and zinc. Particularly
suitable dihydrocarbyl dithiophosphate metal salts are zinc dihydrocarbyl dithiophosphates
(ZDDP). The ZDDP's may have hydrocarbyl groups independently having 1 to 18 carbon
atoms, suitably 2 to 13 carbon atoms or 3 to 18 carbon atoms, more suitably 2 to 12 carbon
atoms or 3 to 13 carbon atoms, for example 3 to 8 carbon atoms. Examples of suitable
hydrocarbyl groups include alkyl, cycloalkyl and alkaryl groups which may contain ether
or ester linkages and also which may contain substituent groups for example, halogen or
nitro groups. The hydrocarbyl groups may be alkyl groups which are linear and/or
branched and suitably may have from 3 to 8 carbon atoms. Particularly suitable ZDDP's
have hydrocarbyl groups which are a mixture of secondary alky groups and primary alkyl
groups for example, 90 mol. % secondary alkyl groups and 10 ol. % primary alkyl
groups.
The oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic
acid, or a derivative thereof additive may reduce the amount of phosphorus- and/or zinccontaining
anti-wear additive which might be required to achieve a desired amount of antiwear
properties for the lubricant composition.
Phosphorus-containing anti-wear additives may be present in the lubricating oil
composition at a concentration of 10 to 6000 ppm by weight of phosphorus, suitably 10 to
1000 ppm by weight of phosphorus, for example 200 to 1400 ppm by weight of
phosphorus, or 200 to 800 ppm by weight of phosphorus or 200 to 600 ppm by weight of
phosphorus.
It has been found that the presence in the lubricant composition of at least one oilsoluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof may assist in the performance of anti-wear additives, such as for
example zinc dihydrocarbyl dithiophosphate additives. This may have an advantage of
reducing the amount of metals, for example zinc, present in the lubricant composition.
This may also have an advantage of reducing the amount of phosphorus-containing antiwear
additives in the lubricant composition which in turn may reduce the amount of
phosphorus in the exhaust emissions when the lubricant is used to lubricate an internal
combustion engine. The reduction in the amount of phosphorus in the exhaust emissions
may have benefits for any exhaust after treatment system.
Other Friction Modifiers.
The lubricant composition and the additive concentrate for a lubricant composition
may further comprise at least one friction modifier other than the additive which is oilsoluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof. Such other friction modifiers may be ash-producing additives or ashless
additives. Examples of such other friction modifiers include fatty acid derivatives
including for example, fatty acid esters, amides, amines, and ethoxylated amines.
Examples of suitable ester friction modifiers include esters of glycerol for example, mono-,
di-, and tri-oleates, mono-palmitates and mono-myristates. A particularly suitable fatty
acid ester friction modifier is glycerol monooleate. Examples of such other friction
modifiers may also include molybdenum compounds for example, organo molybdenum
compounds, molybdenum dialkyldithiocarbamates, molybdenum dialkylthiophosphates,
molybdenum disulphide, tri-molybdenum cluster dialkyldithiocarbamates, non-sulphur
molybdenum compounds and the like. Suitable molybdenum-containing compounds are
described for example, in EP-1533362-A1 for example in paragraphs [0101] to [01 17].
Friction modifiers other than the additive which is oil-soluble mono-, di-, or tri¬
glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof may also
include a combination of an alkoxylated hydrocarbyl amine and a polyol partial ester of a
saturated or unsaturated fatty acid or a mixture of such esters, for example as described in
WO 93/21288.
The additive of the present invention may be used as an alternative to other friction
modifiers or may reduce the amount of such other friction modifiers which might be
required to achieve a desired friction property for the lubricant composition. This may
have an advantage of reducing the amount of metals, for example molybdenum, present in
the lubricant composition.
Friction modifiers other than the additive which is oil-soluble mono-, di-, or tri¬
glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof which are
fatty acid derivative friction modifiers may be present in the lubricating oil composition at
a concentration of 0.01 to 5 % by weight actives, more suitably in the range of 0.01 to 1.5
% by weight actives.
Molybdenum containing friction modifiers may be present in the lubricating oil
composition at a concentration of 10 to 1000 pp by weight molybdenum, more suitably
in the range of 400 to 600 ppm by weight.
Other Additives.
The lubricant composition and the additive concentrate for a lubricant composition
may also comprise other additives. Examples of such other additives include dispersants
(metallic and non-metallic), dispersant viscosity modifiers, detergents (metallic and nonmetallic),
viscosity index improvers, viscosity modifiers, pour point depressants, rust
inhibitors, corrosion inhibitors, antioxidants (sometimes also called oxidation inhibitors),
anti-foams (sometimes also called anti-foaming agents), seal swell agents (sometimes also
called seal compatibility agents), extreme pressure additives (metallic, non-metallic,
phosphorus containing, non-phosphorus containing, sulphur containing and non-sulphur
containing), surfactants, demulsifiers, anti-seizure agents, wax modifiers, lubricity agents,
anti-staining agents, chromophoric agents and metal deactivators.
Dispersants
Dispersants (also called dispersant additives) help hold solid and liquid contaminants
for example resulting from oxidation of the lubricant composition during use, in
suspension and thus reduce sludge flocculation, precipitation and/or deposition for
example on lubricated surfaces. They generally comprise long-chain hydrocarbons, to
promote oil-solubility, and a polar head capable of associating with material to be
dispersed. Examples of suitable dispersants include oil soluble polymeric hydrocarbyl
backbones each having one or more functional groups which are capable of associating
with particles to be dispersed. The functional groups may be amine, alcohol, aminealcohol,
amide or ester groups. The functional groups may be attached to the hydrocarbyl
backbone through bridging groups. More than one dispersant may be present in the
additive concentrate and/or lubricant composition.
Examples of suitable ashless dispersants include oil soluble salts, esters, aminoesters,
amides, imides and oxazolines of long chain hydrocarbon-substituted mono- and
polycarboxylic acids or anhydrides thereof; thiocarboxylate derivatives of long chain
hydrocarbons; long chain aliphatic hydrocarbons having polyamine moieties attached
directly thereto; Mannich condensation products formed by condensing a long chain
substituted phenol with formaldehyde and polyalkylene polyamine; Koch reaction products
and the like. Examples of suitable dispersants include derivatives of long chain
hydrocarbyl-substituted carboxylic acids, for example in which the hydrocarbyl group has
a number average molecular weight of up to 20000, for example 300 to 20000, 500 to
10000, 700 to 5000 or less than 15000. Examples of suitable dispersants include
hydrocarbyl-substituted succinic acid compounds, for example succinimide, succinate
esters or succinate ester amides and in particular, polyisobutenyl succinimide dispersants.
The dispersants may be borated or non-borated. A suitable dispersant is ADX 222.
Dispersant Viscosity Modifiers.
Additionally or alternatively, dispersancy may be provided by polymeric compounds
capable of providing viscosity index improving properties and dispersancy. Such
compounds are generally known as dispersant viscosity improver additives or
multifunctional viscosity improvers. Examples of suitable dispersant viscosity modifiers
may be prepared by chemically attaching functional moieties (for example amines,
alcohols and amides) to polymers which tend to have number average molecular weights
of at least 5000, for example in the range 20000 to 600000 (for example as determined by
gel permeation chromatography or light scattering methods). Examples of suitable
dispersant viscosity modifiers and methods of making them are described in WO
99/21902, WO2003/099890 and WO2006/099250. More than one dispersant viscosity
modifier may be present in the additive concentrate and/or lubricant composition.
Detergents
Detergents (also called detergent additives) may help reduce high temperature
deposit formation for example on pistons in internal combustion engines, including for
example high-temperature varnish and lacquer deposits, by helping to keep finely divided
solids in suspension in the lubricant composition. Detergents may also have acidneutralising
properties. Ashless (that is non-metal containing detergents) may be present.
Metal-containing detergent comprises at least one metal salt of at least one organic acid,
which is called soap or surfactant. Detergents may be overbased in which the detergent
comprises an excess of metal in relation to the stoichiometric amount required to neutralise
the organic acid. The excess metal is usually in the form of a colloidal dispersion of metal
carbonate and/or hydroxide. Examples of suitable metals include Group I and Group 2
metals, more suitably calcium, magnesium and combinations thereof, especially calcium.
More than one metal may be present.
Examples of suitable organic acids include sulphonic acids, phenols (sulphurised or
preferably sulphurised and including for example, phenols with more than one hydroxyl
group, phenols with fused aromatic rings, phenols which have been modified for example
alkylene bridged phenols, and Mannich base-condensed phenols and saligenin-type
phenols, produced for example by reaction of phenol and an aldehyde under basic
conditions) and sulphurised derivatives thereof, and carboxylic acids including for
example, aromatic carboxylic acids (for example hydrocarbyl-substituted salicylic acids
and sulphurised derivatives thereof, for example hydrocarbyl substituted salicylic acid and
derivatives thereof). More than one type of organic acid may be present.
Additionally or alternatively, non-metallic detergents may be present. Suitable nonmetallic
detergents are described for example in US762243 1.
More than one detergent may be present in the lubricant composition and/or additive
concentrate.
Viscosity Index Improvers/Viscosity Modifiers
Viscosity index improvers (also called viscosity modifiers, viscosity improvers or VI
improvers) impart high and low temperature operability to a lubricant composition and
facilitate it remaining shear stable at elevated temperatures whilst also exhibiting
acceptable viscosity and fluidity at low temperatures.
Examples of suitable viscosity modifiers include high molecular weight hydrocarbon
polymers (for example polyisobutylene, copolymers of ethylene and propylene and higher
alpha-olefins); polyesters (for example polymethacrylates); hydrogenated poly(styrene-cobutadiene
or isoprene) polymers and modifications (for example star polymers); and
esterified poly(styrene-co-maleic anhydride) polymers. Oil-soluble viscosity modifying
polymers generally have number average molecular weights of at least 15000 to 1000000,
preferably 20000 to 600000 as determined by gel permeation chromatography or light
scattering methods.
Viscosity modifiers may have additional functions as multifunction viscosity
modifiers. More than one viscosity index improver may be present.
Pour Point Depressants
Pour point depressants (also called lube oil improvers or lube oil flow improvers),
lower the minimum temperature at which the lubricant will flow and can be poured.
Examples of suitable pour point depressants include C to C1 dialkyl fumarate/vinyl
acetate copolymers, methacrylates, polyacrylates, polyarylamides, polymethacrylates,
polyalkyl methacrylates, vinyl fumarates, styrene esters, condensation products of
haloparaffin waxes and aromatic compounds, vinyl carboxylate polymers, terpolymers of
dialkyfumarates, vinyl esters of fatty acids and allyl vinyl ethers, wax naphthalene and the
like.
More than one pour point depressant may be present.
Rust inhibitors
Rust inhibitors generally protect lubricated metal surfaces against chemical attack by
water or other contaminants. Examples of suitable rust inhibitors include non-ionic
polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, polyoxyalkylene
polyols, anionic alky sulphonic acids, zinc dithiophosphates, metal phenolates, basic metal
sulphonates, fatty acids and amines.
More than one rust inhibitor may be present.
Corrosion Inhibitors
Corrosion inhibitors (also called anti-corrosive agents) reduce the degradation of
metallic parts contacted with the lubricant composition. Examples of corrosion inhibitors
include phosphosulphurised hydrocarbons and the products obtained by the reaction of
phosphosulphurised hydrocarbon with an alkaline earth metal oxide or hydroxide, nonionic
polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, thiadiazoles,
triazoles and anionic alkyl sulphonic acids. Examples of suitable epoxidised ester
corrosion inhibitors are described in US2006/0090393.
More than one corrosion inhibitor may be present.
Antioxidants
Antioxidants (sometimes also called oxidation inhibitors) reduce the tendency of oils
to deteriorate in use. Evidence of such deterioration might include for example the
production of varnish-like deposits on metal surfaces, the formation of sludge and viscosity
increase. ZDDP's exhibit some antioxidant properties.
Examples of suitable antioxidants other than ZDDP's include alkylated
diphenylamines, N-alkylated phenylenediamines, phenyl-a-naphthylamine, alkylated
phenyl-a-naphthylarnines, dimethylquinolines, trimethyldihydroquinolines and oligomeric
compositions derived therefrom, hindered phenolics (including ashless (metal-free)
phenolic compounds and neutral and basic metal salts of certain phenolic compounds),
aromatic amines (including alkylated and non-alkylated aromatic amines), sulphurised
alkyl phenols and alkali and alkaline earth metal salts thereof, alkylated hydroquinones,
hydroxylated thiodiphenyl ethers, alkylidenebisphenols, thiopropionates, metallic
dithiocarbamates, 1,3,4-dimercaptothiadiazole and derivatives, oil soluble copper
compounds (for example, copper dihydrocarbyl thio- or thio-phosphate, copper salts of a
synthetic or natural carboxylic acids, for example a C8 to C1 fatty acid, an unsaturated acid
or a branched carboxylic acid, for example basic, neutral or acidic Cu1 and/or Cu salts
derived from alkenyl succinic acids or anhydrides), alkaline earth metal salts of
alkylphenolthioesters, suitably having C5 to C 2 alkyl side chains, calcium nonylphenol
sulphide, barium i-octylphenyl sulphide, dioctylphenylamine, phosphosulphised or
sulphurised hydrocarbons, oil soluble phenates, oil soluble sulphurised phenates, calcium
dodecylphenol sulphide, phosphosulphurised hydrocarbons, sulphurised hydrocarbons,
phosphorus esters, low sulphur peroxide decomposers and the like.
More than one anti oxidant may be present. More than one type of anti oxidant may
be present.
Antifoams
Anti-foams (sometimes also called anti-foaming agents) retard the formation of
stable foams. Examples of suitable anti-foam agents include silicones, organic polymers,
siloxanes (including poly siloxanes and (poly) dimethyl siloxanes, phenyl methyl
siloxanes), acrylates and the like.
More than one anti-foam may be present.
Seal Swell Agents
Seal swell agents (sometimes also called seal compatibility agents or elastomer
compatibility aids) help to swell elastomeric seals for example by causing a reaction in the
fluid or a physical change in the elastomer. Examples of suitable seal swell agents include
long chain organic acids, organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (for example butylbenzyl phthalate) and polybutenyl succinic anhydride.
More than one seal swell agent may be present.
Other Additives
Examples of other additives which may be present in the lubricant composition
and/or additive concentrate include extreme pressure additives (including metallic, nonmetallic,
phosphorus containing, non-phosphorus containing, sulphur containing and nonsulphur
containing extreme pressure additives), surfactants, demulsifiers, anti-seizure
agents, wax modifiers, lubricity agents, anti-staining agents, chromophoric agents and
metal deactivators.
Some additives may exhibit more than one function.
The amount of demulsifier, if present, might be higher than in conventional
lubricants to off-set any emulsifying effect of the mono-, di-, or tri-glyceride additive.
Solvent
The additive concentrate for a lubricant composition may comprise solvent.
Examples of suitable solvents include highly aromatic, low viscosity base stocks, for
example 100N, 60 N and 100SP base stocks.
The representative suitable and more suitable independent amounts of additives (if
present) in the lubricant composition are given in Table 2. The concentrations expressed in
Table 2 are by weight of active additive compounds that is, independent of any solvent or
diluent.
More than one of each type of additive may be present. Within each type of additive,
more than one class of that type of additive may be present. More than one additive of
each class of additive may be present. Additives may suitably be supplied by
manufacturers and suppliers in solvent or diluents.
Table 2
Lubricant Composition
Suitable amount More suitable amount
ADDITIVE TYPE (actives), if present (actives), if present
(by weight) (by weight)
Oil-soluble mono-, di-, or tri-glyceride of at
least one hydroxy polycarboxylic acid, or a 0.02 to 5% 0.1 to 2.5%
derivative thereof
corresponding to 10 corresponding to 10
Phosphorus-containing anti-wear additives
to 6000 ppm P to 1000 ppm P
corresponding to 10 corresponding to 40
Molybdenum-containing anti-wear additives
to 1000 ppm Mo to 600 ppm Mo
corresponding to 10 corresponding to 50
Boron-containing anti-wear additives
to 250 ppm B to 100 ppm B
Friction modifiers other than the mono-, di-,
or tri-glyceride of at least one hydroxy 0.01 to 5 % 0.01 to 1.5 %
polycarboxylic acid, or a derivative thereof
corresponding to 10 corresponding to 400
Molybdenum-containing friction modifiers
to 1000 ppm Mo to 600 ppm Mo
Dispersants 0.1 to 20 % 0.1 to 8%
Detergents 0.01 to 6 % 0.01 to 4 %
Viscosity index improvers 0.01 to 20% 0.01 to 15%
Pour point depressants 0.01 to 5 % 0.01 to 1.5 %
Corrosion and/or rust inhibitors 0.01 to 5 % 0.01 to 1.5%
Anti-oxidants 0.1 to 10 % 0.5 to 5 %
corresponding to 1 corresponding to 1 to
Antifoams containing silicon
to 20 ppm Si 10 ppm Si
Lubricant Applications.
The mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid or a
derivative may be used as an anti-wear additive and/or friction modifier in a non-aqueous
lubricant composition and/or in a fuel composition.
The oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic
acid, or a derivative thereof may be used as an anti-wear additive and/or friction modifier
in a lubricant composition which is a functional fluid, for example a metalworking fluid
which may be used to lubricate metals during machining, rolling and the like. Suitably, the
lubricant composition is a lubricant composition according to the present invention.
The oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic
acid, or a derivative thereof may be used as an anti-wear additive and/or friction modifier
in a lubricant composition which is a power transmission fluid for example as an automatic
transmission fluid, a fluid in a clutch (for example a dual clutch), a gear lubricant, or in
other automotive applications and the like. Suitably, the lubricant composition is a
lubricant composition according to the present invention. The additive and lubricant
composition may suitably be used in aviation lubricant applications.
The mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid or a
derivative may be used as an anti-wear additive and/or friction modifier in a non-aqueous
lubricant composition and/or in a fuel composition used to lubricate a solid surface,
including for example metallic surfaces and non-metallic surfaces. Suitable metallic
surfaces include surfaces of ferrous based materials, for example cast iron and steels;
surfaces of aluminium-based solids, for example aluminium-silicon alloys; surfaces of
metal matrix compositions; surfaces of copper and copper alloys; surfaces of lead and lead
alloys; surfaces of zinc and zinc alloys; and surfaces of chromium-plated materials.
Suitable non-metallic surfaces include surfaces of ceramic materials; surfaces of polymer
materials; surfaces of carbon-based materials; and surfaces of glass. Other surfaces which
may be lubricated include surfaces of coated materials for example surfaces of hybrid
materials for example metallic materials coated with non-metallic materials and nonmetallic
materials coated with metallic materials; surfaces of diamond-like carbon coated
materials and SUMEBore™ materials for example as described in Sultzer technical review
4/2009 pages 11-13.
The glyceride may be used in a non-aqueous lubricant composition and/or in a fuel
composition to lubricate a surface at any typical temperature which might be encountered
in a lubricating environment, for example at a temperature such as may be encountered in
an internal combustion engine, for example a temperature in the range of ambient to 250
°C, e.g. 90 to 120 °C. Typically ambient temperature may be 20 °C, but may be less than
20°C, for example 0°C.
Internal Combustion Engine Lubrication.
The oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic
acid, or a derivative thereof may be used as an anti-wear additive and/or friction modifier
in a lubricant composition which may be used to lubricate an internal combustion engine,
for example as a crankcase lubricant. The engine may be a spark-ignition, internal
combustion engine, or a compression-ignition, internal combustion engine. The internal
combustion engine may be a spark-ignition internal combustion engine used in automotive
or aviation applications. The internal combustion engine may be a two-stroke
compression-ignition engine and the oil-soluble mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof may be used as an anti-wear additive
and/or friction modifier in a system oil lubricant composition and/or a cylinder oil
lubricant composition used to lubricate the engine. The two-stroke compression-ignition
engine may be used in marine applications.
In the method of lubricating an internal combustion engine according to the present
invention, the mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid or
derivative thereof may be present in a lubricant composition used to lubricate the engine,
for example to lubricate the crankcase of the engine. Suitably, such a lubricant
composition is a lubricant composition according to the present invention.
The mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or
derivative thereof may be added to the lubricant composition used to the lubricate the
engine by slow release of the additive into the lubricant - for example by contacting the
lubricant composition with a gel comprising the additive, for example as described in
US6843916 and international PCT patent application publication WO 2008/008864 and/or
by controlled release of the additive, for example when the back pressure of lubricant
passing through a filter exceeds a define back pressure, for example as described in
international PCT patent application publication WO2007/148047.
Additionally, or alternatively the mono-, di- or tri-glyceride of at least one hydroxyl
polycarboxylic acid, or a derivative thereof may be present in the fuel for an internal
combustion engine. In use, the diglyceride additive may pass with or without fuel into a
lubricant composition used to lubricate the engine, for example as a crankcase lubricant
and thereby provide antiwear and/or friction modifier benefits to the engine.
Thus according to a further aspect of the present invention, there is provided a fuel
composition for an internal combustion engine which composition comprises a major
amount of a liquid fuel and a minor amount of at least one additive which is an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof.
The engine may be a spark-ignition, internal combustion engine, or a compressionignition,
internal combustion engine. The engine may be a homogeneous charge
compression ignition internal combustion engine. The internal combustion engine may be
a spark-ignition internal combustion engine used in automotive or aviation applications.
The internal combustion engine may be a two-stroke compression-ignition engine. The
two-stroke compression-ignition engine may be used in marine applications.
The mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof is present in the fuel at a concentration of up to 500 ppm by weight, for
example 20 to 200 ppm by weight or 50 to 100 ppm by weight.
Typically, the rate of ingress of fuel into crankcase lubricant is higher for sparkignition
internal combustion engines than for compression-ignition engines. However, the
rate at which fuel ingresses into the crankcase lubricant for compression-ignition engines
may depend and may increase depending upon the use of post-injection strategies for
operation of the engine.
The mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof, present in the fuel composition may reduce wear in the fuel system of
the engine, for example the fuel pump.
Fuels
Suitable liquid fuels, particularly for internal combustion engines include
hydrocarbon fuels, oxygenate fuels and combinations thereof. Hydrocarbon fuels may be
derived from mineral sources and/or from renewable sources such as biomass (e.g.
biomass-to-liquid sources) and/or from gas-to-liquid sources and/or from coal-to-liquid
sources. Suitable sources of biomass include sugar (e.g. sugar to diesel fuel) and algae.
Suitable oxygenate fuels include alcohols for example, straight and/or branched chain alkyl
alcohols having from 1 to 6 carbon atoms, esters for example, fatty acid alkyl esters and
ethers, for example methyl tert butyl ether. Suitable fuels may also include LPG-diesel
fuels (LPG being liquefied petroleum gas). The fuel composition may be an emulsion.
However, suitably, the fuel composition is not an emulsion.
Suitable fatty acid alkyl esters include methyl, ethyl, propyl, butyl and hexyl esters.
Usually, the fatty acid alkyl ester is a fatty acid methyl ester. The fatty acid alkyl ester
may have 8 to 25 carbon atoms, suitably, 12 to 25 carbon atoms, for example 16 to 18
carbon atoms. The fatty acid may be saturated or unsaturated. Usually, the fatty acid alkyl
ester is acyclic. Fatty acid alkyl esters may be prepared by esterification of one or more
fatty acids and/or by transesterification of one or more triglycerides of fatty acids. The
triglycerides may be obtained from vegetable oils, for example, castor oil, soyabean oil,
cottonseed oil, sunflower oil, rapeseed oil (which is sometimes called canola oil), Jatropha
oil or palm oil, or obtained from tallow (for example sheep and/or beef tallow), fish oil or
used cooking oil. Suitable fatty acid alkyl esters include rapeseed oil methyl ester (RME),
soya methyl ester or combinations thereof.
The fuel composition according to the present invention may be prepared by
admixing in one or more steps a hydrocarbon fuel, an oxygenate fuel or a combination
thereof with an effective amount of at least one additive which is a mono-, di- or triglyceride
of at least one hydroxy polycarboxylic acid, or a derivative thereof and
optionally at least one other fuel additive.
The method of preparing a fuel composition and the method of improving the
antiwear and/or friction properties of a liquid fuel comprise admixing in one or more steps
said liquid fuel (which may be for example a hydrocarbon fuel, an oxygenate fuel or a
combination thereof) with an effective amount of at least one additive which is a mono-,
di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof and
optionally at least one other fuel additive.
The fuel may be admixed with at least one additive in one or more steps by methods
known in the art. The additives may be admixed as one or more additive concentrates or
part additive package concentrates, optionally comprising solvent or diluent. The
hydrocarbon fuel, oxygenate fuel or combination thereof may be prepared by admixing in
one or more steps by methods known in the art, one or more base fuels and components
therefor, optionally with one or more additives and or part additive package concentrates.
The additives, additive concentrates and/or part additive package concentrates may be
admixed with the fuel or components therefor in one or more steps by methods known in
the art.
Fuels and Concentrates For Compression-ignition Engines.
The fuel composition of the present invention may be suitable for use in an internal
combustion engine which is a compression-ignition internal combustion engine, suitably a
direct injection diesel engine, for example of the rotary pump, in-line pump, unit pump,
electronic unit injector or common rail type, or in an indirect injection diesel engine. The
fuel composition may be suitable for use in heavy and/or light duty diesel engines.
The fuel composition for compression-ignition internal combustion engines may have
a sulphur content of up to 500 ppm by weight, for example, up to 15 ppm by weight or up
to 10 ppm by weight. The fuel composition for compression-ignition internal combustion
engines may meet the requirements of the EN590 standard, for example as set out in BS
EN 590:2009.
Suitable oxygenate components in the fuel composition for compression-ignition
internal combustion engines include fatty acid alkyl esters, for example fatty acid methyl
esters. The fuel may comprise one or more fatty acid methyl esters complying with EN
14214 at a concentration of up to 7 % by volume. Oxidation stability enhancers may be
present in the fuel composition comprising one or more fatty acid alkyl or methyl esters,
for example at a concentration providing an action similar to that obtained with 1000
g kg of 3,5-di-tert-butyl-4-hydroxy-toluol (also called butylated hydroxyl-toluene or
BHT). Dyes and/or markers may be present in the fuel composition for compressionignition
internal combustion engines.
The fuel composition for compression-ignition internal combustion engines may have
one or more of the following, for example, as defined according to BS EN 590:2009 :- a
minimum cetane number of 5 1.0, a minimum cetane index of 46.0, a density at 15 °C of
820.0 to 845.0 kg/m3, a maximum polycyclic aromatic content of 8.0% by weight, a flash
point above 55°C, a maximum carbon residue (on 10% distillation) of 0.30 % by weight, a
maximum water content of 200 mg/kg, a maximum contamination of 24 mg/kg, a class 1
copper strip corrosion (3 h at 50 °C), a minimum oxidation stability limit of 20 h according
to EN 1575 1 and a maximum oxidation stability limit of 25 g m3 according to EN ISO
12205, a maximum limit for lubricity corrected wear scar diameter at 60 °C of 460m , a
minimum viscosity at 40°C of 2.00 mm2/s and a maximum viscosity at 40°C of 4.50
mm2/s, < 65% by volume distillation recovery at 250°C, a minimum distillation recovery at
350°C of 85% by volume and a maximum of 95 % by volume recovery at 360°C.
The fuel composition and the additive concentrate for a fuel composition suitable for
use in a compression-ignition internal combustion engine may further comprise at least one
friction modifier other than the additive which is a mono-, di- or tri-glyceride of at least
one hydroxy polycarboxylic acid, or a derivative thereof. Such other friction modifiers
include compounds described herein as friction modifiers for lubricant compositions and
additive concentrates for lubricant compositions.
The fuel composition and the additive concentrate for a fuel composition suitable for
use with a compression-ignition internal combustion engine may further comprise at least
one lubricity additive. Suitable lubricity additives include tall oil fatty acids, mono- and
di-basic acids and esters.
The fuel composition and the additive concentrate for a fuel composition suitable for
use in a compression-ignition internal combustion engine may further comprise
independently one or more cetane improver, one or more detergent, one or more anti¬
oxidant, one or more anti-foam, one or more demulsifier, one or more cold flow improver,
one or more pour point depressant, one or more biocide, one or more odorant, one or more
colorant (sometimes called dyes), one or more marker, one or more spark aiders and/or
combinations of one or more thereof. Other suitable additives which may be present
include thermal stabilizers, metal deactivators, corrosion inhibitors, antistatic additives,
drag reducing agents, emulsifiers, dehazers, anti-icing additives, antiknock additives, antivalve-
seat recession additives, surfactants and combustion improvers, for example as
described in EP-21 07 102-A.
The additive concentrate for a fuel composition for a compression-ignition internal
combustion engine may comprise solvent. Suitable solvents include carrier oils (for
example mineral oils), polyethers (which may be capped or uncapped), non-polar solvents
(for example toluene, xylene, white spirits and those sold by Shell companies under the
trade mark "SHELLSOL"), and polar solvents (for example esters and alcohols e.g.
hexanol, 2-ethylhexanol, decanol, isotridecanol and alcohol mixtures, for example those
sold by Shell companies under the trade mark "LINEVOL", e.g. LINEVOL 79 alcohol
which is a mixture of C - primary alcohols, or a C 2. 4 alcohol mixture which is
commercially available.
Suitable cetane improvers include 2-ethyl hexyl nitrate, cyclohexyl nitrate and dirt-
butyl peroxide. Suitable antifoams include siloxanes. Suitable detergents include
polyolefin substituted succinimides and succinamides of polyamines, for example
polyisobutylene succinimides, polyisobutylene amine succinimides, aliphatic amines,
Mannich bases and amines and polyolefin (e.g. polyisobutylene) maleic anhydride.
Suitable antioxidants include phenolic antioxidants (for example 2,6-di-tert-butylphenol)
and aminic antioxidants (for example N,N'-di-sec-butyl-p-phenylenediamine). Suitable
anti-foaming agents include polyether-modified polysiloxanes.
The representative suitable and more suitable independent amounts of additives (if
present) in the fuel composition suitable for a compression-ignition engine are given in
Table 3. The concentrations expressed in Table 3 are by weight of active additive
compounds that is, independent of any solvent or diluent.
The additives in the fuel composition suitable for use in compression-ignition internal
combustion engines are suitably present in a total amount in the range of 100 to 1500 ppm
by weight. Therefore, the concentrations of each additive in an additive concentrate will
be correspondingly higher than in the fuel composition, for example by a ratio of 1: 0.0002
to 0.0015. The additives may be used as part-packs, for example part of the additives
(sometimes called refinery additives) being added at the refinery during manufacture of a
fungible fuel and part of the additives (sometimes called terminal or marketing additives)
being added at a terminal or distribution point. The at least one additive which is a mono-,
di- or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof may
suitably be added or used as a refinery or marketing additive, preferably as a marketing
additive for example at a terminal or distribution point.
0934
36
Table 3
Fuels and Concentrates For Spark-ignition Engines.
The fuel composition of the present invention may be suitable for use in an internal
combustion engine which is a spark-ignition internal combustion engine.
The fuel composition for spark-ignition internal combustion engines may have a
sulphur content of up to 50.0 ppm by weight, for example up to 10.0 ppm by weight.
The fuel composition for spark-ignition internal combustion engines may be leaded
or unleaded.
The fuel composition for spark-ignition internal combustion engines may meet the
requirements of EN 228, for example as set out in BS EN 228:2008. The fuel composition
for spark-ignition internal combustion engines may meet the requirements of ASTM D
4814-09b.
The fuel composition for spark-ignition internal combustion engines may have one or
more of the following, for example, as defined according to BS EN 228:2008 :- a
minimum research octane number of 95.0, a minimum motor octane number of 85.0 a
maximum lead content of 5.0 mg 1, a density of 720.0 to 775.0 kg/m3, an oxidation stability
of at least 360 minutes, a maximum existent gum content (solvent washed) of 5 mg/1 00
ml, a class 1 copper strip corrosion (3 h at 50 °C), clear and bright appearance, a maximum
olefin content of 18.0 % by weight, a maximum aromatics content of 35.0 % by weight,
and a maximum benzene content of 1.00 % by volume.
Suitable oxygenate components in the fuel composition for spark-ignition internal
combustion engines include straight and/or branched chain alkyl alcohols having from 1 to
6 carbon atoms, for example methanol, ethanol, n-propanol, n-butanol, isobutanol, tertbutanol.
Suitable oxygenate components in the fuel composition for spark-ignition internal
combustion engines include ethers, for example having 5 or more carbon atoms. The fuel
composition may have a maximum oxygen content of 2.7% by mass. The fuel
composition may have maximum amounts of oxygenates as specified in EN 228, for
example methanol: 3.0% by volume, ethanol: 5.0% by volume, iso-propanol: 10.0 % by
volume, iso-butyl alcohol: 10.0 % by volume, tert-butanol: 7.0% by volume, ethers (C5 or
higher): 10% by volume and other oxygenates (subject to suitable final boiling point):
10.0% by volume. The fuel composition may comprise ethanol complying with EN 15376
at a concentration of up to 5.0% by volume.
The fuel composition and the additive concentrate for a fuel composition suitable for
use in a spark-ignition internal combustion engine may further comprise at least one
friction modifier other than the additive which is a mono-, di- or tri-glyceride of at least
one hydroxy polycarboxylic acid, or a derivative thereof. Such other friction modifiers
include compounds described herein as friction modifiers for lubricant compositions and
additive concentrates for lubricant compositions.
The fuel composition and the additive concentrate for a fuel composition suitable for
use in a spark-ignition internal combustion engine may further comprise independently one
or more detergent, one or more octane improver, one or more friction modifier, one or
more anti-oxidant, one or more valve seat recession additive, one or more corrosion
inhibitor, one or more anti-static agent, one or more odorant, one or more colorant, one or
more marker and/or combinations of one or more thereof.
The additive concentrate for a fuel composition for a spark-ignition internal
combustion engine may comprise solvent. Suitable solvents include polyethers and
aromatic and/or aliphatic hydrocarbons, for example heavy naphtha e.g. Solvesso (Trade
mark), xylenes and kerosine.
Suitable detergents include poly isobutylene amines (PIB amines) and polyether
amines.
Suitable octane improvers include N-methyl aniline, methyl cyclopentadienyl
manganese tricarbonyl (MMT) (for example present at a concentration of up to 120 ppm
by weight), ferrocene (for example present at a concentration of up to 16 ppm by weight)
and tetra ethyl lead (for example present at a concentration of up to 0.7 g/1, e.g. up to 0.15
¹ )
Suitable anti-oxidants include phenolic anti-oxidants (for example 2,4-di-tertbutylphenol
and 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid) and aminic anti¬
oxidants (for example para-phenylenediamine, dicyclohexylamine and derivatives thereof).
Suitable corrosion inhibitors include ammonium salts of organic carboxylic acids,
amines and heterocyclic aromatics, for example alkylamines, imidazolines and
tolyltriazoles.
Valve seat recession additives may be present at a concentration of up to 15000 ppm
by weight, for example up to 7500 ppm by weight.
The representative suitable and more suitable independent amounts of additives (if
present) in the fuel composition suitable for a spark-ignition engine are given in Table 4.
The concentrations expressed in Table 4 are by weight of active additive compounds that
is, independent of any solvent or diluent.
The additives in the fuel composition suitable for use in spark-ignition internal
combustion engines are suitably present in a total amount in the range of 20 to 25000 ppm
by weight. Therefore, the concentrations of each additive in an additive concentrate will
be correspondingly higher than in the fuel composition, for example by a ratio of 1:
0.00002 to 0.025. The additives may be used as part-packs, for example part of the
additives (sometimes called refinery additives) being added at the refinery during
manufacture of a fungible fuel and part of the additives (sometimes called terminal or
marketing additives) being added at a terminal of distribution point. The at least one
additive which is a mono-, di- or tri-glyceride of at least one hydroxy polycarboxylic acid,
or a derivative thereof may suitably be added or used as a refinery or marketing additive,
preferably as a marketing additive for example at a terminal or distribution point.
Table 4
The invention will now be described by way of example only with reference to the
following experiments and examples in which examples according to the present invention
are labelled numerically as Example 1, Example 2 etc. and experiments not according to
the present invention are labelled alphabetically as Experiment A, Experiment B etc.
Preparation of Lubricant Compositions.
A 5W-30 lubricant composition (Lubricant A) was prepared to model a typical
lubricant composition suitable for passenger cars with either compression-ignition or
spark-ignition internal combustion engines, but having a lower ZDDP content than a
typical lubricant. The lubricant composition was made by admixing additives as in a
commercially available additive package containing dispersant, detergent, antioxidant,
antifoam and ZDDP (but with reduced amount of ZDDP) with a Group III base oil, a pour
point depressant, viscosity modifier and dispersant viscosity modifier.
A lubricant composition (Lubricant 1) according to the present invention was
prepared in the same way as Lubricant A but with 1.2 % by weight Citrem SP 70 (Trade
Mark) (a diglyceride of citric acid and oleic/linoleic acid).
Several other lubricant compositions (Lubricants B to D) were prepared as Lubricant
1 but with friction modifiers/anti-wear additives other than Citrem SP70 as indicated
below. Thus, Lubricant B used glycerol monooleate (HiTEC 7133), Lubricant C used
triethyl citrate and Lubricant D used Sakura-lube 165, the active component of which is
which is molybdenum dithiocarbamate (MoDTC).
Lubricants A to D are not according to the present invention because the lubricant
compositions do not contain any mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof. Lubricant 1 is according to the present
invention.
All the lubricant compositions had a ZDDP content corresponding to 0.0285 % by
weight phosphorus.
1. Wear Testing of Lubricant Compositions.
Thin layer activation (TLA) wear tests were undertaken for Lubricants A to D and
Lubricant 1.
The TLA wear test is a radio nucleotide wear test used to simulate cam follower wear
in an engine. Wearing components were radioactively activated and the rate at which
radioactive metal was worn off and accumulated in the oil was measured to assess the wear
in nm/h. The results for the tests performed at 40°C, are shown in Table 5. Experiments A
to D are not according to the present invention because the lubricant compositions do not
contain any mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof. Example 1 is according to the present invention.
The results in Table 5 show that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric
acid and an unsaturated C carboxylic acid (e.g. oleic and/or linoleic acid), for example
Citrem SP70 (trade mark), exhibits good anti-wear properties in a lubricant composition,
for example when used in combination with a low concentration of zinc dihydrocarbyl
dithiophosphates (ZDDP), for example corresponding to 285 pp phosphorus.
Table 5.
2. Cameron Plint Wear Tests .
Cameron Plint wear tests were undertaken for lubricants with the same compositions
as those used in the previously-described tests.
The Cameron Plint rig wear test was used to simulate reciprocating boundary friction
and produce wear at higher temperatures (100°C). The apparatus was set up in a pin on
plate configuration. The pin was reciprocated along the plate at a frequency of 25 Hz,
stroke length of 2.3 mm and with an applied pressure of 150N. Oil was fed into the contact
area at a rate of 3 ml/hr. Standard steel B01 Flat Plate and EN3 1 Roller plint components
were used in these tests. The results from 10 hour tests are shown in Table 6. Experiments
E to H are not according to the present invention because the lubricant compositions do not
contain any mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof. Example 2 is according to the present invention.
Table 6.
The results in Table 6 show that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric
acid and an unsaturated C18 carboxylic acid (e.g. oleic and or linoleic acid), for example
Citrem SP70 (trade mark), exhibits good anti-wear properties in a lubricant composition,
for example when used in combination with a low concentration of zinc dihydrocarbyl
dithiophosphates (ZDDP), for example corresponding to 285 ppm phosphorus.
3. Four-Ball Wear Tests .
Four-Ball wear tests according to ASTM D 4172 but modified to test mild and hence
discriminating conditions of 30 kg and 60 minutes were undertaken for lubricants with the
same compositions as those used in the previously-described tests. In the 4 ball wear test,
one ball bearing was rotated above a cradle of three others in the presence of a lubricant.
The results are shown in Table 7. Experiments I to L are not according to the present
invention because the lubricant compositions do not contain any mono-, di-, or triglyceride
of at least one hydroxy polycarboxylic acid or a derivative. Example 3 is
according to the present invention.
Table 7.
The results in Table 7 show that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric
acid and an unsaturated Ci8 carboxylic acid (e.g. oleic and/or linoleic acid), for example
Citrem SP70 (trade mark), exhibits good anti-wear properties in a lubricant composition,
for example when used in combination with a low concentration of zinc dihydrocarbyl
dithiophosphates (ZDDP), for example corresponding to 285 ppm phosphorus.
4. HFRR Friction Tests.
A High Frequency Reciprocating Rig friction test was undertaken for lubricants with
the same compositions as those used in the previously-described tests.
The HFRR test is usually used to assess lubricity of diesel fuels (according to ASTM
D6079-97). It may also be used to assess friction coefficients between sliding solid
surfaces in the presence of lubricant compositions with various friction modifiers over a
temperature range and hence the test may be used to assess the performance of the friction
modifiers.
The results are shown in Table 8. Experiments M to P are not according to the
present invention because the lubricant compositions do not contain any mono-, di-, or triglyceride
of at least one hydroxy polycarboxylic acid, or a derivative thereof. Example 4
is according to the present invention.
Table 8
Note: FC = friction coefficient
The results in Table 8 show that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric
acid and oleic acid, for example Citrem SP70 (trade mark), exhibits good friction modifier
properties in a lubricant composition, for example when used in combination with a low
concentration of zinc dihydrocarbyl dithiophosphates (ZDDP), for example corresponding
to 285 pp phosphorus.
The results in Table 8 also indicate that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric
acid and an unsaturated C18 carboxylic acid (e.g. oleic and/or linoleic acid), for example
Citrem SP70 (trade mark) may be used as a friction modifier in a fuel composition for an
internal ignition engine, for example a fuel composition for a compression-ignition engine.
5. Sequence IVA Engine Wear Tests.
Sequence IVA engine tests according to ASTM test method ASTM D6891 were
undertaken for 0W-20 lubricant compositions. The Sequence IVA test is an industry
standard test used to evaluate the camshaft wear protection of internal combustion engine
lubricant compositions.
The lubricants contained an additive package comprising dispersant, detergents
(calcium sulphonate and phenate), antioxidants (phenolic and aminic), anti-foam and a
Yubase 4 diluent. The additive package was typical of that used for standard lubricant
compositions for internal combustion engines of the compression-ignition or spark-ignition
type such as might be used for passenger cars. All but one of the lubricant compositions
had a low concentration of zinc dihydrocarbyl dithiophosphates (ZDDP) corresponding to
a phosphorus concentration of 375 ppm by weight. The lubricants were prepared by
admixing the additive package, ZDDP, Group III base oil and the required anti-wear
additive/friction modifier, if present.
Lubricants 2 and 3 used in Examples 5 and 6 were according to the present
invention and were prepared using an oil-soluble mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxylic acid, or a derivative thereof which was Citrem SP 70 in an amount
of 1.2% by weight and 0.5 % by weight respectively.
Lubricant E was prepared as Lubricants 2 and 3 but without an oil-soluble mono-, di-
, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof.
Lubricant F was prepared as Lubricant E, but using a higher treat rate of ZDDP
corresponding to 800 ppm of phosphorus.
Lubricants G to H were prepared as Lubricant E but using different anti-wear
additive/friction modifiers as shown in Table 9.
Lubricants E, F and G used in Experiments Q, R and S respectively were not
according to the present invention because they were prepared without an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof.
The lubricants had a low HTHS viscosity (according to ASTM D4683) of 2.6 cP and
were of O -20 grade. The results are shown in Table 9.
Table 9
Notes: (1) 800 ppm P
(2) Re-measured 165.63 m i
(3) Re-measured 81.52 m .
Iron concentrations in the lubricant compositions were measured during the tests and
were found to correlate well with the measured wear results.
The results in Table 9 show that the mono-, di-, or tri-glyceride of at least one
hydroxy polycarboxyhc acid, or a derivative thereof and in particular a diglyceride of citric
acid and an unsaturated C carboxylic acid (e.g. oleic and/or linoleic acid), for example
Citrem SP70 (trade mark), exhibits very good anti-wear properties in a lubricant
composition, for example when used in combination with a low concentration of zinc
dihydrocarbyl dithiophosphates (ZDDP), for example corresponding to 375 ppm
phosphorus.
In particular, the results in Table 9 show that the mono-, di-, or tri-glyceride of at
least one hydroxy polycarboxyhc acid, or a derivative thereof and in particular a
diglyceride of citric acid and an unsaturated C 8 carboxylic acid (e.g. oleic and/or linoleic
acid), for example Citrem SP70 (trade mark) is more effective for example at a
concentration of 0.5 % (Example 6) than higher concentrations of MoDTC (Experiment S).
The results also show that reducing the amount of the mono-, di-, or tri-glyceride of
at least one hydroxy polycarboxylic acid, or a derivative thereof and in particular a
diglyceride of citric acid and an unsaturated C18 carboxylic acid (e.g. oleic and/or linoleic
acid), for example Citrem SP70 (trade mark) does not significantly reduce the anti-wear
performance - compare for example, Examples 5 and 6.
6. Ml 11-FE Engine Test
Lubricant G and Lubricant 2 were tested in an Ml 11-FE engine test according to
CEC-L-54-T-96 using a Mercedes Benz engine and found to have 3.32% fuel efficiency
and 3.17% fuel efficiency respectively compared to the reference 15W-40 lubricant.
These results show that the mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof and in particular a diglyceride of citric acid and
an unsaturated C 8 carboxylic acid (e.g. oleic and/or linoleic acid), for example Citrem
SP70 (trade mark), exhibits comparable friction modification with 400 ppm molybdenum
provided by SKI 65, which is a molybdenum-containing additive commercially available
from Asahi Denka Kogyo K.K.

Claims
1. The use of an oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof, as an anti-wear additive and/or friction
modifier in a non-aqueous lubricant composition and/or in a fuel composition.
2. The use as claimed in claim 1 in which the lubricant composition is used to lubricate
an internal combustion engine.
3. The use as claimed in claim 2 in which the oil-soluble mono-, di-, or tri-glyceride of
at least one hydroxy polycarboxylic acid, or a derivative thereof, is provided in a liquid
fuel composition used to operate the internal combustion engine, and a portion at least, of
said glyceride ingresses into the lubricating oil composition during operation of said
engine.
4. A non-aqueous lubricant composition comprising a major amount of an oil of
lubricating viscosity and a minor amount of at least one additive which is an oil-soluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a derivative
thereof together with more than one other lubricant additive.
5. A fuel composition for an internal combustion engine which composition comprises a
major amount of a liquid fuel and a minor amount of at least one additive which is an oilsoluble
mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid, or a
derivative thereof at a concentration of up to 500 pp by weight.
6. The use or composition as claimed in any one of the preceding claims in which the
hydroxy polycarboxylic acid has at least one hydroxy group which is in an alpha position
with respect to a carboxylic moiety.
7. The use or composition as claimed in claim 6 in which the hydroxy polycarboxylic
acid is citric acid.
8. The use or composition as claimed in any one of claims 1 to 7 in which the glyceride
is a glyceride of at least one hydroxy polycarboxylic acid and at least one second
carboxylic acid which is a saturated, mono-unsaturated or poly-unsaturated, branched or
linear, monocarboxylic or polycarboxylic acid having 4 to 22 carbon atoms, or a derivative
thereof.
9. The use or composition as claimed in any one of claims 1 to 7 in which the glyceride
is a glyceride of at least one hydroxy polycarboxylic acid and a mono-unsaturated C to
C22 monocarboxylic acid, or a derivative thereof.
10. The use or composition as claimed in any one of claims 1 to 7 in which the glyceride
is a glyceride of at least one hydroxy polycarboxylic acid and a polyunsaturated C4 to C
monocarboxylic acid, or a derivative thereof.
11. The use or composition as claimed in claim 9 or claim 10 in which the glyceride is a
glyceride of at least one hydroxy polycarboxylic acid and a mono-unsaturated or
polyunsaturated Ci8 monocarboxylic acid, or a derivative thereof.
12. The use or composition as claimed in claim 11 in which the glyceride is a glyceride
of citric acid and a mono-unsaturated or polyunsaturated C1 monocarboxylic acid, or a
derivative thereof.
13. The use or composition as claimed in any one of claims 9 to 12 in which the monounsaturated
or polyunsaturated C4 to C22 carboxylic acid is linear.
14. The use or composition as claimed in any one of claims 1 to 7 in which the glyceride
is a glyceride of citric acid and oleic acid, a glyceride of citric acid and linoleic acid or a
mixture thereof.
15. The use or composition as claimed in claim 8 in which the carboxylic acid having 4
to 22 carbon atoms is a polycarboxylic acid and the derivative is an ester of a carboxylic
acid moiety of said polycarboxylic acid.
16. The use or composition as claimed in any one of the preceding claims in which the
derivative of the glyceride is an ether of the hydroxyl moiety of the hydroxy
polycarboxylic acid.
17. The use or composition as claimed in any one of claims 1 to 15 in which the
derivative of the glyceride is an ester of the hydroxyl moiety of the hydroxy polycarboxylic
acid.
18. The use or composition as claimed in any one of the preceding claims in which the
derivative of the glyceride is an ester of a carboxylic acid moiety of the hydroxy
polycarboxylic acid.