USE OF A BORON-CONTAINING ADDITIVE AS AN INHIBITOR OF LEAD
CORROSION
This invention relates to the use of boron-containing additives in non-aqueous
lubricant compositions as inhibitors of lead corrosion associated with ashless, organic
ester, anti-wear additives and/or friction modifiers.
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. It is further known to use boron-containing
additives in lubricant compositions, for example as dispersants.
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:....".
A range of materials are known to be useful as anti-wear additives and/or friction
modifiers in lubricant compositions; for example, 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 combustion
engines, they give rise to ash which contributes to particulate matter in exhaust emissions
from the internal combustion engines. Thus, in order to reduce the amount of ash-forming
additives used for lubricating internal combustion engines, and also to reduce the amount
of zinc and/or phosphorus and/or sulphur in the exhaust emissions from internal
combustion engines, a variety of ashless, organic ester, anti-wear additives and/or friction
modifiers have been developed for use in non-aqueous lubricant compositions and fuel
compositions.
A potential disadvantage of such ashless organic ester anti-wear additives and/or
friction modifiers is that their use is sometimes associated with an increase in lead
corrosion, which can reduce their usefulness, particularly with respect to engines having
relatively high proportions of lead containing components.
Whilst various materials have been suggested as corrosion inhibitors (also known as
anti-corrosive agents), none have been identified as specifically inhibiting lead corrosion
associated with ashless, organic ester, anti-wear additives and/or friction modifiers.
Additionally, many known corrosion inhibitors are relatively expensive, and their
incorporation in non-aqueous lubricant compositions can significantly increase the price of
such compositions. Still further, these materials may adversely affect one or more other
properties of the lubricant compositions in which they are incorporated. In general
therefore, it would be beneficial if such materials could be replaced by lower cost materials
and/or materials that provide additional beneficial properties to the lubricant composition
in which they are incorporated, such as anti-wear and/or friction reduction properties.
Boron-containing additives are often added to lubricant compositions, for example as
dispersants, and boron-containing dispersants help to 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. However, boron-containing additives have not previously
been shown to inhibit lead corrosion associated with ashless, organic ester, anti-wear
additives and/or friction modifiers. In particular, there has been no suggestion whatsoever
that borated ester dispersants are particularly suitable for such uses.
International patent application publication WO2008/124191 relates to a lubricating
composition comprising a major amount of a GTL lubricating base oil and a friction
modifier consisting essentially of oil soluble fatty acid esters of a polyol. According to
WO2008/124191, the friction modifier is one or more fatty acid esters of a polyol, and it is
stated that suitable polyols include diols, triols and the like, such as ethylene glycol,
propylene glycol, glycerol and sorbitol. It is also stated that the esters of these polyols are
those of carboxylic acids containing 1 to 24 carbon atoms, and that examples of such
carboxylic acids include octadecanoic acid, dodecanoic acid, stearic acid, lauric acid and
oleic acid. WO2008/124191 makes no reference to lead corrosion associated with the use
of ashless, organic ester, anti-wear additives and/or friction modifiers, and does not suggest
the use of boron-containing additives to inhibit such corrosion.
International patent application publication WO201 1/161406 relates to 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. According to WO201 1/161406,
lubricant compositions comprising the oil-soluble mono-, di-, or tri-glyceride of at least
one hydroxy polycarboxylic acid, or a derivative thereof, may be used to lubricate internal
combustion engines. It is stated that in one embodiment, the hydroxy polycarboxylic acid
has at least one hydroxy group which is in an alpha position with respect to a carboxylic
moiety. Particularly desirable results are said to have been obtained with additives 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. WO 201 1/161406 makes no reference to lead corrosion
associated with the use of ashless, organic ester, anti-wear additives and/or friction
modifiers, and does not suggest the use of boron-containing additives to inhibit such
corrosion.
International patent application publication WO 2012/056191 relates to the use as an
anti-wear additive and/or friction modifier in a non-aqueous lubricant composition and/or
in a fuel composition of at least one long chain fatty acid ester of a hydroxy carboxylic
acid in which the long chain fatty acid has at least 4 carbon atoms and the ester is an oilsoluble
ester of a mono- or poly- hydroxy carboxylic acid containing 1 to 4 groups which
are independently carboxylic acid groups or lower hydrocarbyl esters thereof and in which,
when the hydroxy carboxylic acid is a mono-hydroxy carboxylic acid, the ester has a long
chain fatty acid ester moiety of the hydroxy group of the hydroxy carboxylic acid and,
when the hydroxy carboxylic acid is a poly-hydroxy carboxylic acid, the ester has
independently long chain fatty acid ester moieties of one or two of the hydroxy groups of
the poly-hydroxy carboxylic acid. According to WO 2012/056191, lubricant compositions
comprising the specified long chain fatty acid esters of hydroxyl carboxylic acids may be
used to lubricate internal combustion engines. WO 2012056191 makes no reference to
lead corrosion associated with the use of ashless, organic ester, anti-wear additives and/or
friction modifiers, and does not suggest the use of boron-containing additives to inhibit
such corrosion.
US Patent US 6,008,165 relates to compositions for reducing the copper-lead bearing
corrosion of a formulation that includes a major amount of an oil of lubricating viscosity
and a minor amount of a corrosion-reducing additive comprising (a) a borated dispersant
with a total base number of from 20 to 160 on an oil-free basis; (b) a metal salt of a
phosphorous acid; (c) a metal overbased composition comprising at least one carboxylate,
phenate, or sulfonate wherein the metal is lithium, sodium, potassium, magnesium or
calcium, and wherein the composition further comprises (d) a borate ester. According to
US 6,008,165, copper-lead bearing corrosion may be reduced in formulations wherein the
borated ester and borated dispersant provide from 20 to 800 ppm mass of boron in the
composition. US 6,008,165 makes no reference to lead corrosion associated with the use
of ashless, organic ester, anti-wear additives and/or friction modifiers, and does not suggest
the use of boron-containing additives, such as borated ester dispersants, to inhibit such
corrosion.
US Patent US 6,010,986 relates to compositions for reducing the copper-lead bearing
corrosion of a formulation that includes a major amount of an oil of lubrication viscosity
and a minor amount of a corrosion-reducing additive comprising: (a) a dispersant with a
total base number of from 20 to 160 on an oil-free basis, with the proviso that the
dispersant is substantially boron-free; (b) a metal salt of a phosphorous acid; (c) a metal
overbased composition comprising at least one carboxylate, phenate, or sulfonate wherein
the metal is lithium, sodium, potassium, magnesium or calcium, and wherein the additive
further comprises (d) a borate ester. US Patent US 6,010,986 makes no reference to lead
corrosion associated with the use of ashless, organic ester, anti-wear additives and/or
friction modifiers, and does not suggest the use of boron-containing additives, for example
borated ester dispersants, to inhibit such corrosion.
US Patent US 4,536,306 relates to diol-phosphorous oxyhalide-boron compound
reaction products. According to US 4,536,306 the reaction products have anti-oxidant and
anti-friction properties, and hinder the corrosion of copper surfaces. US 4,536,306 makes
no reference to lead corrosion associated with the use of ashless organic ester anti-wear
additives and/or friction modifiers, and does not suggest the use of boron-containing
additives, for example borated ester dispersants, to inhibit such corrosion.
US Patent Application publication US 2008/0128184 relates to fully formulated
lubricating oil, lubricating surface, and lubricant additive concentrates for lubricants. The
lubricating oil composition has therein a dispersant mixture derived from a reaction
product of polyalkylene compound, a carboxylic acylating agent, and a polyamine. The
polyalkylene compound of at least one dispersant in the dispersant mixture has a number
average molecular weight of at least 1200 and at least one dispersant in the dispersant
mixture contains boron such that a weight ratio of boron to nitrogen in the dispersant
mixture ranges from above about 0.25 to about 1.0. US 2008/128184 makes no reference
to lead corrosion associated with the use of ashless organic ester anti-wear additives and/or
friction modifiers, and does not suggest the use of boron-containing additives, for example
borated ester dispersants, to inhibit such corrosion.
International Patent Application Publication WO 02/062930 relates to a lubricating
oil composition, comprising (a) a base oil and (b) a boron-containing compound selected
from specified organo-boron compounds; the lubricating oil composition containing
sulphur, boron and, optionally, phosphorous with the ratio of sulphur:boron:phosphorous
being controlled within a specified range; the concentration of sulphur in the lubricating oil
composition being from 0.01% to 0.25% by weight and the concentration of phosphorous
in the lubricating oil composition being up to 0.08% by weight. According to
WO 02/062930, in at least one embodiment, the lubricating oil composition exhibits
enhanced thermal stability, seal compatibility and/or lead corrosion resistance
characteristics. WO 02/062930 makes no reference to lead corrosion associated with the
use of ashless organic ester anti-wear additives and/or friction modifiers, and does not
suggest the use of boron-containing additives, for example borated ester dispersants, to
inhibit such corrosion.
There remains a need for alternative materials that may be used as inhibitors of lead
corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in non-aqueous lubricant compositions, including materials that have additional
properties, for example being effective dispersants, in such compositions.
Thus, according to the present invention there is provided the use of a boroncontaining
additive in a non-aqueous lubricant composition as an inhibitor of lead
corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers.
Also according to another aspect of the present invention there is provided a method
of improving the anti-corrosion properties, for example inhibiting lead corrosion associated
with ashless, organic ester, anti-wear additives and/or friction modifiers, of an oil of
lubricating viscosity, which method comprises admixing said oil with an effective amount
of at least one additive which is a boron-containing additive.
The present invention solves the technical problem defined above by the use of a
boron-containing additive in a non-aqueous lubricant composition as an inhibitor of lead
corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers.
Uses of the non-aqueous lubricant compositions incorporating boron-containing
additives as inhibitors of lead corrosion associated with ashless, organic ester, anti-wear
additives and/or friction modifiers include all conventional lubricant purposes; for
example, to lubricate an internal combustion engine. In at least some examples, the use of
boron-containing additives as inhibitors of lead corrosion in non-aqueous lubricant
compositions permits the compositions to be used to provide effective lubrication and
reduced lead corrosion, for example when the non-aqueous lubricant composition also
comprises one or more ashless, organic ester, anti-wear additives and/or friction modifiers,
for example, at concentrations of greater than 0.1 wt%, greater than 0.2 wt%, greater than
0.5 wt%, greater than 0.75 wt% or greater than 1.0 wt%.
In at least some examples, the numerical percentages referenced in this application
may be preceded by the word "about."
In at least some examples, the use of boron-containing additives as inhibitors of lead
corrosion in non-aqueous lubricant compositions permits the compositions to be used to
provide effective lubrication and reduced lead corrosion to an internal combustion engine
when the liquid fuel composition used to operate the internal combustion engine comprises
an ashless, organic ester, anti-wear additive and/or friction modifier, and a portion of the
said ashless, organic ester, anti-wear additive and/or friction modifier ingresses into the
non-aqueous lubricant composition during operation of said engine, irrespective of whether
the lubricant composition also comprises an ashless, organic ester, anti-wear additive
and/or friction modifier.
In at least some examples, the use of boron-containing additives in non-aqueous
lubricant compositions as inhibitors of lead corrosion associated with ashless, organic
ester, anti-wear additives and/or friction modifiers permits the compositions to be used to
provide effective lubrication to internal combustion engines having high proportions of
lead containing components, particularly if the lubricant compositions and/or the liquid
fuel compositions used to operate the internal combustion engines comprise one or more
ashless, organic ester, anti-wear additives and/or friction modifiers, for example at
concentrations of greater than 0.1 wt%, greater than 0.2 wt%, greater than 0.5 wt%, greater
than 0.7 wt% or greater than 1.0 wt%.
The use of boron-containing additives in non-aqueous lubricant compositions as
inhibitors of lead corrosion associated with ashless, organic ester, anti-wear additives
and/or friction modifiers effectively reduces the lead corrosion in engines lubricated with
said compositions when said compositions and/or the liquid fuel compositions used to
operate said engines comprise one or more ashless, organic ester, anti-wear additives
and/or friction modifiers, for example at levels associated with significant lead corrosion,
for example when compared to compositions that are otherwise the same other than for the
absence of a boron-containing additive.
Methods for measuring lead corrosion include standard methods, for example using a
high temperature corrosion bench test (HTCBT) or an engine test such as the Sequence
VIII test. In at least some examples, the use of a boron-containing additive in a non
aqueous lubricant composition comprising such an amount of an ashless, organic ester,
anti-wear additive and/or friction modifier such that it would normally fail a HTCBT
and/or Sequence VIII test will permit the non-aqueous lubricant composition to pass such a
test.
The amount of boron-containing additive used in a non-aqueous lubricant
composition as an inhibitor of lead corrosion associated with ashless, organic ester, antiwear
additives and/or friction modifiers includes any amount suitable to act as an inhibitor
of lead corrosion, for example a concentration at which it provides both effective inhibition
of lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers, and effective dispersant properties, for example from 0.1 to 20 wt%, 0.1 to 10
wt% or 0.1 to 8 wt%, for example 0.5 wt% or 1.0 wt%.
In at least some examples, the amount of boron-containing additive is selected so that
the total boron content of the non-aqueous lubricant composition is at least 200 ppm by
weight, for example at least 250 ppm by weight, at least 280 ppm by weight or at least 300
ppm by weight.
Any boron-containing additive may be used as an inhibitor of lead corrosion
associated with ashless, organic ester anti-wear additives and/or friction modifiers in
accordance with the present invention, and the total boron content in a non-aqueous
lubricant composition may be derived from more than one boron-containing additive.
In at least some examples, the boron-containing additive is a borated dispersant. By
borated dispersant is meant a metallic or non-metallic material which helps to hold solid
and liquid contaminants, for example resulting from oxidation of a lubricant composition
during use, in suspension and thus reduce sludge flocculation, precipitation and/or
deposition, for example on lubricated surfaces, and which comprises boron as a component
thereof. In at least some examples, the borated dispersant is a borated ester, for example a
borated succinate ester or a borated succinate ester amide. In at least some examples, the
boron-containing additive is tris-2-ethylhexyl borate or a borated polyisobutenyl
succinimide dispersant.
In at least some examples, the boron-containing additive is an inhibitor of lead
corrosion associated with an ashless, organic ester, anti-wear additive and/or friction
modifier which is:
i) at least one fatty acid ester of a polyol,
ii) at least one oil-soluble mono, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof;
iii) at least one long chain fatty acid ester of a hydroxy carboxylic acid in which
the long chain fatty acid has at least 4 carbon atoms and the ester is an oilsoluble
ester of a mono- or poly- hydroxy carboxylic acid containing 1 to 4
groups which are independently carboxylic acid groups or lower hydrocarbyl
esters thereof and in which, when the hydroxy carboxylic acid is a monohydroxy
carboxylic acid, the ester has a long chain fatty acid ester moiety of
the hydroxy group of the hydroxy carboxylic acid and, when the hydroxy
carboxylic acid is a poly-hydroxy carboxylic acid, the ester has independently
long chain fatty acid ester moieties of one or two of the hydroxy groups of the
poly-hydroxy carboxylic acid; or
iv) a mixture thereof.
Fatty Acid Esters of Polyols
Where the ashless, organic ester, anti-wear additive and/or friction modifier
associated with lead corrosion is at least one fatty acid ester of a polyol, suitable polyols
include diols, triols and the like, such as ethylene glycol, propylene glycol, glycerol and
sorbitol. Examples of the esters of these polyols are those of carboxylic acids containing
12 to 24 carbon atoms. Examples of such carboxylic acids include octadecanoic acid,
dodecanoate acid, stearic acid, lauric acid and oleic acid. In at least some examples, the
fatty acid ester is a glycerol ester, for example a glycerol mono-ester, including for
example glycerol mono-oleate, glycerol monostearate, glycerol monolaurate, glycerol
dodecanoate and glycerol octadodecanoate.
Oil-soluble Glycerides of at least one Hydroxy Polycarboxylic Acid, or Derivatives
Thereof
Where the ashless, organic ester, anti-wear additive and/or friction modifier
associated with lead corrosion is at least one oil-soluble mono, di-, or tri- glyceride of at
least one hydroxy polycarboxylic acid, or a derivative thereof, in at least some examples,
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.
In at least some examples, each hydroxy polycarboxylic acid independently has from
4 to 22 carbon atoms, for example 4 to 15 carbon atoms. In at least some examples, the
oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy polycarboxylic acid or
derivative thereof has from 16 to 80 carbon atoms. The number of carbon atoms in the
glyceride may affect its solubility in oil of lubricating viscosity.
By oil-soluble is meant that the glyceride is soluble in an oil of lubricating viscosity
for example in a pour point depressant and friction modifying and/or anti-wear improving
amount, for example in an amount by weight of at least 200 ppm in an oil of lubricating
viscosity. In at least some examples, the solubility is determined at ambient temperature,
for example at 20°C. Methods of determining the solubility include those for determining
solubility 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).
Examples of the oil-soluble mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof include 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 containing to 22 carbon atoms, or a derivative
thereof.
In at least some examples, the second carboxylic acid is saturated, mono-unsaturated
or poly-unsaturated. In at least some examples, the second carboxylic acid is unsaturated.
In at least some examples, the second carboxylic acid is branched or linear. In at least
some examples, the second carboxylic acid is a monocarboxylic or polycarboxylic acid. If
the second carboxylic acid is a polycarboxylic acid, the derivative of the glyceride includes
those in which the glyceride is 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 cis-\3-
docosenoic acid) and brassidic acid.
In at least some examples, the glyceride is a glyceride of citric acid and oleic acid, a
glyceride of citric acid and linoleic acid or a mixture thereof.
In at least some examples, the mono-, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid or derivative thereof is represented by the general formula (I):
OR'
RO - CH2 - C - CH2 - OR" (I)
wherein RO, OR' and OR" independently represent:
-OH;
a saturated, mono-unsaturated or poly-unsaturated, branched or linear,
monocarboxylic or polycarboxylic group containing from 4 to 22 carbon atoms or an ether
or an ester thereof; or
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.
In at least some examples, 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 containing from 4 to 22 carbon atoms or an ester
thereof.
In at least some examples, 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 at least some examples, in formula (I) each hydroxy polycarboxylic moiety
independently has from 4 to 22 carbon atoms. In formula (I) the hydroxy polycarboxylic
moiety, in at least some examples, is 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 containing from 4 to 22 carbon atoms or an ester thereof, in at least
some examples, is 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 containing from 4 to 22 carbon atoms or an ester
thereof may be derivable from unsaturated carboxylic acids or their halide equivalents.
Suitable mono-unsaturated 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.
In at least some examples, the glyceride is a glyceride of at least one hydroxy
polycarboxylic acid and a saturated C4 to C22 polycarboxylic acid, or a derivative thereof.
Suitable polycarboxylic acids include branched and linear acids. In at least some
examples, the glyceride is a glyceride of at least one hydroxy polycarboxylic acid and a
mono-unsaturated or polyunsaturated C4 to C22 polycarboxylic acid, or a derivative thereof.
Suitable polycarboxylic acids include branched and linear acids. In at least some examples
glyceride is a glyceride of at least one hydroxy polycarboxylic acid and a saturated C4 to
C22 monocarboxylic acid, or a derivative thereof. Suitable monocarboxylic acids include
branched and linear acids. Suitable saturated C1 monocarboxylic acids include palmitic
acid. Suitable saturated C18 monocarboxylic acids include stearic acid. In at least some
examples, the glyceride is a glyceride of at least one hydroxy polycarboxylic acid and a
mono-unsaturated or polyunsaturated C4 to C22 monocarboxylic acid, or a derivative
thereof. Suitable unsaturated monocarboxylic acids include branched and linear acid. In at
least some examples, the glyceride is a glyceride of at least one hydroxy polycarboxylic
acid and an unsaturated Ci monocarboxylic acid, or a derivative thereof. Suitable
monocarboxylic acid include branched and linear acids. 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 C1
monocarboxylic acids include oleic acid and linoleic acid.
In at least some examples, the glyceride is a citric acid ester of a mono-glyceride of a
saturated, mono-unsaturated or polyunsaturated, branched or linear, monocarboxylic or
polycarboxylic C4 to C22 carboxylic acid, for example, a C16 or C1 carboxylic acid, for
example palmitic acid, stearic acid, oleic acid or linoleic acid. Suitable glycerides include
citric acid ester of mono-glyceride made from vegetable oil, for example sunflower and/or
palm oil. Suitable glycerides include citric acid ester of mono-glyceride made from edible,
refined sunflower and palm based oil. Suitably, 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-O-CH 2-CH -CH2 -O-C -CH2 - C-CH2-COOH
OH
wherein -Y- represents a C16 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 containing 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 1 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
(paragraph [0033]). In the example at paragraphs [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 paragraph [0171], Triglyceride lubricants
including anionic surfactant worked well as dry conveyor lubricants and effectively
lubricated after water was applied to the conveyor. According to paragraph [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 paragraphs [0065] to [0075] often classes of
anionic surfactant.
According to paragraph [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 suitable glycerides include 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 acid, 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.
In at least some examples, the derivative of the glyceride is an ester of the at least one
hydroxy polycarboxylic acid moiety. Suitable esters include esters of a carboxylic acid
moiety of the hydroxy polycarboxylic acid. In at least some examples, each carboxylic
acid moiety of the hydroxyl polycarboxylic acid is independently derivatisable as an ester.
Suitable ester derivatives include hydrocarbyl esters, in which the hydrocarbyl moiety has,
for example, from 4 to 22 carbon atoms. Suitable hydrocarbyl moieties include alkyl
moieties which have, for example, from 4 to 22 carbon atoms. In at least some examples,
the hydrocarbyl moiety comprises one or more hetero atoms for example nitrogen and/or
oxygen.
In at least some examples, the derivative of the glyceride is an ether or an ester of the
hydroxyl moiety of the hydroxy polycarboxylic acid. In at least some examples, 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 is, for example, independently
derivatisable as an ether or an ester. Suitable ethers include hydrocarbyl ethers. In at least
some examples, the hydrocarbyl moiety of each ether independently has from 1 to 22
carbon atoms, for example from 1 to 18 carbon atoms. In at least some examples, the
hydrocarbyl moiety of each ether is independently an alkyl moiety. Suitable alkyl moieties
EP2015/080227
15
of each ether independently include alkyl moieties containing from 1 to 22 carbon atoms,
for example from 1 to 18 carbon atoms. In at least some examples, the hydrocarbyl moiety
of each ether independently comprises one or more hetero atoms, for example nitrogen
and/or oxygen. In at least some examples, each ester is independently a hydrocarbyl ester.
In at least some examples, the hydrocarbyl moiety of each ester has from 4 to 22 carbon
atoms. Suitable hydrocarbyl moieties of each ester independently include alkyl moieties.
In at least some examples, the alkyl moiety of each ester independently has from 4 to 22
carbon atoms. In at least some examples, the hydrocarbyl moiety of each ester
independently comprises one or more hetero atoms, for example nitrogen and/or oxygen.
If the saturated, mono-unsaturated or polyunsaturated, branched or linear carboxylic
acid containing 4 to 22 carbon atoms is a polycarboxylic acid, the derivative of the
glyceride in at least some examples, is 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 containing from 4 to 22 carbon atoms, if present. In at least some
examples, each ester independently is a hydrocarbyl ester. Suitable hydrocarbyl moieties
of each ester independently include those containing from 4 to 22 carbon atoms. In at least
some examples, the hydrocarbyl moiety is an alkyl moiety. Suitable alkyl moieties of each
ester independently include those containing from 4 to 22 carbon atoms. In at least some
examples, the hydrocarbyl moiety of each ester independently comprises 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. Suitable methods
for the preparation of the di- and tri-glycerides include the partial hydrolysis of a fat to
produce a mono-glyceride followed by esterification with a hydroxy polycarboxylic acid.
Suitable methods for the preparation of the mono-glycerides include esterification of
glycerol with a hydroxy polycarboxylic acid. In at least some examples, the hydrocarbyl
ether derivatives are made from corresponding hydrocarbyl halides.
The oil-soluble mono-, di-, or tri-glycerides of at least one hydroxy polycarboxylic
acid and derivatives thereof do not contain zinc or molybdenum, that is, they are
molybdenum-free and zinc-free. They also are sulphur-free and phosphorus-free.
GRINSTED CITREM SP70 (Trade Mark) has low volatility and low toxicity.
Long Chain Fatty Acid Esters of Hydroxy Carboxylic Acids
Where the ashless, organic ester, anti-wear additive and/or friction modifier
associated with lead corrosion is at least one long chain fatty acid ester of a hydroxy
carboxylic acid in which the long chain fatty acid has at least 4 carbon atoms and the ester
is an oil-soluble ester of a mono- or poly- hydroxy carboxylic acid containing 1 to 4
groups, as defined herein, in at least some examples, the oil-soluble ester has at least one
long chain fatty acid ester moiety in an alpha position with respect to a carboxylic acid
group or lower hydrocarbyl ester thereof.
In at least some examples, the oil-soluble ester defined according to the present
invention contains from 6 to 80 carbon atoms. The number of carbon atoms in the ester
may affect its solubility in oil of lubricating viscosity.
By oil-soluble is meant that the ester is soluble in an oil of lubricating viscosity, for
example in a pour point depressant and friction modifying and/or antiwear improving
amount, for example in an amount by weight of at least 200 ppm in an oil of lubricating
viscosity. In at least some examples, the solubility is determined at ambient temperature,
for example at 20 °C. In at least some examples, the solubility is determined at
atmospheric pressure.
Suitable mono-hydroxy carboxylic acids include:
o glycolic acid (also sometimes called 2-hydroxyethanoic acid; or
hydroxy acetic acid);
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 lactic acid (also sometimes called 2-hydroxypropanoic acid);
o malic acid (also sometimes called hydroxybutanedioic acid);
o monohydroxy trimesic acid; and
o hydrogenated monohydroxy trimesic acid (also sometimes called 1,3,5
tricarboxy, 2-hydroxy cyclohexane).
In at least some examples, the mono-hydroxy carboxylic acid is citric acid.
Suitable poly-hydroxy carboxylic acids include:
o tartaric acid (also sometimes called 2,3-dihydroxybutanedioic acid; or 2,3-
dihydroxysuccinic acid).
In at least some examples, the poly-hydroxy carboxylic acid is tartaric acid.
The long chain fatty acid of the ester contains at least 4 carbon atoms. Examples of
long chain fatty acids include saturated, mono-unsaturated or poly-unsaturated long chain
fatty acids. Examples of long chain fatty acids that are saturated carboxylic acids include,
for example, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic
acid, stearic acid and arachidic acid. Examples of long chain fatty acids that are monounsaturated
or polyunsaturated acids include, for example, oleic acid, linoleic acid,
linolenic acid, myristoleic acid, palmitoleic acid, sapienic acid, erucic acid and brassidic
acid. The long chain fatty acid may be branched or linear. Examples of long chain fatty
acids include monocarboxylic acids and polycarboxylic acids. In at least some examples,
the long chain fatty acid contains 4 to 22 carbon atoms, for example 5 to 22 carbon atoms,
or 8 to 22 carbon atoms, or 8 to 18 carbon atoms or 14 to 22 carbon atoms, for example 8,
14, 16 or 18 carbon atoms, for example 8, 14 or 18 carbons atoms, or for example 14
carbon atoms. Suitable saturated C monocarboxylic acids include octanoic acid. Suitable
saturated C14 monocarboxylic acids include myristic acid. Suitable saturated C1
monocarboxylic acids include palmitic acid. Suitable saturated monocarboxylic acids
include stearic acid. Suitable unsaturated C1 monocarboxylic acids include oleic acid and
linoleic acid.
In at least some examples, each carboxylic acid group of the mono- or poly-hydroxyl
carboxylic acid is independently derivatisable or derivatized as a lower hydrocarbyl ester.
The lower hydrocarbyl esters have hydrocarbyl moieties which independently include for
example those containing 1 to 6 carbon atoms. In at least some examples, the lower
hydrocarbyl moieties are independently straight chain or branched chain alkyl moieties.
Suitable lower hydrocarbyl moieties of the lower hydrocarbyl esters include those for
example that are independently C to C6 alkyl moieties, for example to C3 alkyl
moieties, for example, ethyl moieties.
In at least some examples, the ester is triethyl citrate oleate (sometimes also called
oleyl triethyl citrate). In at least some examples, the ester is triethyl citrate butyrate,
triethyl citrate octanoate or triethyl citrate myristate, for example triethyl citrate myristate.
In at least some examples, the ester is diethyl tartrate dioleate (sometimes also called
diethyl dioleate tartrate or diethyl dioleyl tartrate). In at least some examples, the ester is
diethyl tartrate dibutyrate.
In at least some examples, the long chain fatty acid esters as defined in accordance
with the present invention do not contain zinc or molybdenum, that is, they are
molybdenum-free and zinc-free, and sulphur-free and phosphorus-free. Generally, the
esters as herein defined will have low volatility.
Methods for making the long chain fatty acid esters as defined in accordance with the
present invention are known in the art, for example by reaction of the corresponding long
chain fatty acid with the corresponding mono- or poly-hydroxy carboxylic acid or its
corresponding lower hydrocarbyl esters. Another suitable method involves reaction of an
acyl halide of the corresponding long chain fatty acid with the corresponding mono- or
poly-hydroxy carboxylic acid or its corresponding lower hydrocarbyl esters. For example,
triethyl citrate oleate may be made by reaction of triethyl citrate with oleyl chloride, for
example in the presence of sodium hydride and tetrahydrofuran solvent. The esters may be
made by the Yamaguchi reaction.
The esters may also be made by using enzymes as biological esterification catalysts.
In at least some examples, the at least one fatty acid ester of a polyol, at least one oilsoluble
glyceride of at least one hydroxy polycarboxylic acid, or a derivative thereof, and
the at least one long chain fatty acid ester of a hydroxy carboxylic acid, as defined herein,
are used as pour point depressant additives in non-aqueous lubricant compositions either
alone or in any suitable combination.
Lubricant Compositions
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in any suitable lubricant compositions. Similarly, in at least some examples, the
boron-containing additives are used to improve the anti-corrosion properties, for example
inhibiting lead corrosion associated with ashless, organic ester, anti-wear additives and/or
friction modifiers, of any conventional lubricant compositions. Further details of suitable
lubricant compositions are set out herein.
In at least some examples, the lubricant composition comprises a major amount of oil
of lubricating viscosity and a minor amount of at least one boron-containing additive as an
inhibitor of lead corrosion. Major amount means greater than 50% and minor amount
means less than 50% by weight.
In at least some examples, the lubricant composition and the oil of lubricating
viscosity comprise base oil. Base oil comprises at least one base stock. In at least some
examples, the lubricant composition comprises one or more additives other than the boroncontaining
additive. In at least some examples, the lubricant composition is essentially
free of dispersants other than borated dispersants. In at least some examples, 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, for example, available from ExxonMobil.
Suitable Group II basestocks include EHC 50 and EHC 110, for example, 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 include ester base stocks, for
example Priolube 3970, available from Croda International pic. Suitable Group IV base
stocks include hydrogenated oligomers of alpha olefins. In at least some examples, the
oligomers are 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
In at least some examples, the lubricant composition and the oil of lubricating
viscosity 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 oils derived from coal or shale.
Suitable base oils and base stocks include those 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 include those derived from gas-to-liquids
materials, coal-to-liquids materials, biomass-to-liquids materials and combinations thereof.
Suitable gas-to-liquids (sometimes also referred to as GTL) materials include those
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. Suitable GTL derived base stocks and base oils include
those 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).
Suitable biomass-to-liquids (sometimes also referred to as BTL) materials include
those 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).
Suitable coal-to-liquids materials include those made by gasifying coal to make
synthesis gas which is then converted to hydrocarbons.
In at least some examples, the base oil and/or oil of lubricating viscosity have a
kinematic viscosity at 100 °C in the range of 2 to 100 cSt, for example in the range of 3 to
50 cSt or in the range 3.5 to 25 cSt.
In at least some examples, the lubricant composition is 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, or OW-20.
In at least some examples, the lubricant composition has a High Temperature High Shear
rate (HTHS) viscosity at 150 °C of at least 2.6 cP, for example as measured according to
ASTM D4683, CEC L-36-A-90 or ASTM D5481.
In at least some examples, the lubricant composition has an HTHS viscosity at 150
°C according to ASTM D4683 of from 1 to < 2.6 cP, for example about 1.8 cP.
Methods for preparing the lubricant composition include admixing an oil of
lubricating viscosity with an effective lead corrosion inhibiting amount of at least one
boron-containing additive together with, optionally, at least one other lubricant additive.
Uses and methods of improving the anti-corrosion properties of an oil of lubricating
viscosity according to the present invention, comprise admixing an oil of lubricating
viscosity with an effective lead corrosion inhibiting amount of at least one boroncontaining
additive.
In at least some examples, the oil of lubricating viscosity is admixed with at least one
additive in one or more steps by methods known in the art. In at least some examples, the
additives are admixed as one or more additive concentrates or part additive package
concentrates, optionally comprising solvent or diluent. In at least some examples, the oil
of lubricating viscosity is 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. In at least some examples, the additives,
additive concentrates and/or part additive package concentrates are admixed with oil of
lubricating viscosity or components thereof in one or more steps by methods known in the
art.
Anti-wear Additives
In at least some examples, the lubricant composition comprises an ashless, organic
ester, anti-wear additive and/or friction modifier, as discussed herein.
In at least some examples, the lubricant composition additionally or alternatively
further comprises at least one anti-wear additive other than an ashless, organic ester, antiwear
additive and/or friction modifier. Such other anti-wear additives include ashproducing
additives and 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 anti-wear additives.
Examples of suitable ashless phosphorus-containing anti-wear additives include trilauryl
phosphite and triphenylphosphorothionate and those disclosed in paragraph [0036] of US
2005/0198894. 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. Suitable
dihydrocarbyl dithiophosphate metal salts include zinc dihydrocarbyl dithiophosphates
(ZDDP). Suitable ZDDP's include those comprising hydrocarbyl groups independently
containing 1 to 18 carbon atoms, for example 2 to 13 carbon atoms or 3 to 18 carbon
atoms, or for example 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, examples of which include those comprising ether or ester linkages and
also those that comprise substituent groups, for example halogen or nitro groups. Suitable
hydrocarbyl groups include alkyl groups including, for example, linear and/or branched
alkyl groups including, for example, those containing from 3 to 8 carbon atoms. Suitable
ZDDP's include those comprising hydrocarbyl groups which are a mixture of secondary
alkyl groups and primary alkyl groups, for example 90 mol. % secondary alkyl groups and
10 mol. % primary alkyl groups.
The ashless, organic ester, anti-wear additive and/or friction modifier, where present,
may reduce the amount of phosphorus- and/or zinc- containing anti-wear additive which
might be required to achieve a desired amount of anti-wear properties for the lubricant
composition.
In at least some examples, phosphorus-containing anti-wear additives are present in
the lubricating oil composition at a concentration of 10 to 6000 ppm by weight of
phosphorus, for example 10 to 1000 ppm by weight of phosphorus, or 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
ashless, organic ester, anti-wear additive and/or friction modifier may assist in the
performance of anti-wear additives, such as, for example, zinc dihydrocarbyl
dithiophosphate additives. This may reduce the amount of metals, for example zinc,
present in the lubricant composition.
This may also reduce the amount of phosphorus-containing anti-wear 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.
This may also reduce the amount of sulphur-containing anti-wear additives in the
lubricant composition, which in turn may reduce the amount of sulphur in exhaust
emissions when the lubricant is used to lubricate an internal combustion engine. The
reduction in the amount of sulphur in the exhaust emissions may have benefits for any
exhaust after treatment system.
The use of a boron-containing additive in a non-aqueous lubricant composition in
accordance with the present invention helps to reduce, or even eliminate, lead corrosion
associated with the presence of ashless, organic ester, anti-wear additives and/or friction
modifiers.
Other Friction Modifiers
In at least some examples, the lubricant composition additionally or alternatively
comprises at least one friction modifier other than an additive which is an ashless, organic
ester, anti-wear additive and/or friction modifier. 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 such other friction modifiers also include molybdenum
compounds, for example organo molybdenum compounds, molybdenum
dialkyldithiocarbamates, molybdenum dialkylthiophosphates, molybdenum disulphide, trimolybdenum
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].
Examples of friction modifiers other than an additive which is an ashless, organic
ester, anti-wear additive and/or friction modifier 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.
In at least some examples, an ashless, organic ester, anti-wear additive and/or friction
modifier is used as an alternative to other friction modifiers and/or to reduce the amount of
such other friction modifiers that might be required to achieve a desired friction property
for the lubricant composition. This may reduce the amount of metals, for example
molybdenum, present in the lubricant composition.
In at least some examples, friction modifiers other than an additive which is an
ashless, organic ester, anti-wear additive and/or friction modifier, which are fatty acid
derivative friction modifiers are present in the lubricating oil composition at a
concentration of 0.01 to 5 % by weight actives, for example in the range of 0.01 to 1.5 %
by weight actives.
In at least some examples, the molybdenum containing friction modifiers may be
present in the lubricating oil composition at a concentration of 10 to 1000 ppm by weight
molybdenum, for example in the range of 400 to 600 ppm by weight.
Other Additives.
In at least some examples, the lubricant composition also comprises other additives.
Examples of such other additives include non-boron-containing dispersants (metallic and
non-metallic), dispersant viscosity modifiers, detergents (metallic and non-metallic),
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.
Non-Boron-Containing Dispersants
In at least some examples, the lubricant compositions comprise non-boron-containing
dispersants, in addition to borated dispersants. Suitable non-boron-containing dispersants
generally comprise long-chain hydrocarbons, to promote oil-solubility, and a polar head
capable of associating with material to be dispersed. Examples of suitable non-boroncontaining
dispersants include oil soluble polymeric hydrocarbyl backbones each
containing one or more functional groups which are capable of associating with particles to
be dispersed. Suitable functional groups include amine, alcohol, amine-alcohol, amide and
ester groups. In at least some examples, the functional groups are attached to the
hydrocarbyl backbone through bridging groups. In at least some examples, more than one
dispersant is present in the lubricant composition.
Examples of suitable ashless non-boron-containing dispersants include oil soluble
salts, esters, amino-esters, amides, imides and oxazolines of long chain hydrocarbonsubstituted
mono- and polycarboxylic acids or anhydrides thereof; thiocarboxylate
derivatives of long chain hydrocarbons; long chain aliphatic hydrocarbons containing
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 non-boroncontaining
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 non-boron-containing dispersants include hydrocarbyl-substituted
succinic acid compounds, for example succinimide, succinate esters or succinate ester
amides and in particular, polyisobutenyl succinimide dispersants. A suitable non-borated
dispersant is ADX 222.
Dispersant Viscosity Modifiers
Additionally or alternatively, in at least some examples, dispersancy is 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. Methods of preparing such suitable
dispersant viscosity modifiers include chemically attaching functional moieties (for
example, amines, alcohols and amides) to polymers which tend to have number average
molecular weights of at least 15000, 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. In at least some
examples, more than one dispersant viscosity modifier is present in the 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. In at least some examples, ashless (that is non-metal containing
detergents) are present. Metal-containing detergents comprise 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, for example calcium, magnesium and combinations
thereof. In at least some examples, more than one metal is present.
Examples of suitable organic acids include sulphonic acids, phenols (non-sulphurised
or 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. In at least some examples, more than one type of
organic acid is present.
In at least some examples, additionally or alternatively, non-metallic detergents are
present. Suitable non-metallic detergents are described, for example, in US7,622,43 1.
In at least some examples, more than one additional detergent is present in the
lubricant composition.
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 15,000 to
1,000,000, preferably 20,000 to 600,000 as determined by gel permeation chromatography
or light scattering methods.
Viscosity modifiers may have additional functions as multifunction viscosity
modifiers. In at least some examples more than one viscosity index improver is present.
Pour Point Depressants
Pour point depressants (also called lube oil improvers or lube oil flow improvers),
lower the minimum temperature in which the lubricant will flow and can be poured.
Examples of suitable pour point depressants include C8 to C 8 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
dialkylfumarates, vinyl esters of fatty acids and allyl vinyl ethers, wax naphthalene and the
like.
In at least some examples, more than one pour point depressant is 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 alkyl sulphonic acids, zinc dithiophosphates, metal phenolates, basic metal
sulphonates, fatty acids and amines.
In at least some examples, more than one rust inhibitor is present.
Additional Corrosion Inhibitors
In at least some examples, the lubricant composition comprises no corrosion
inhibitors other than boron-containing additives. Alternatively, in at least some examples,
the lubricant composition comprises one or more corrosion inhibitors in addition to the
boron-containing additives. Examples of additional 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.
In at least some examples, more than one additional corrosion inhibitor is 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-naphthylamines, 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 acid, for example a C to C fatty acid, an unsaturated acid
or a branched carboxylic acid, for example basic, neutral or acidic Cu1 and/or Cu1 salts
derived from alkenyl succinic acids or anhydrides), alkaline earth metal salts of
alkylphenolthioesters, for example, containing C5 to C12 alkyl side chains, calcium
nonylphenol sulphide, barium t-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.
In at least some examples, more than one antioxidant is present. In at least some
examples, more than one type of antioxidant is 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.
In at least some examples, more than one anti-foam is 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.
In at least some examples, more than one seal swell agent is present.
Other Additives
In at least some examples, other additives are present in the lubricant composition
and these include, for example, 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 ashless, organic ester, anti-wear additives
and/or friction modifiers, where present.
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.
In at least some examples, more than one of each type of additive is present. Within
each type of additive, in at least some examples, more than one class of that type of
additive is present. In at least some examples, more than one additive of each class of
additive is present. In at least some examples, additives are 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)
Boron-containing additives 0.1 to 20% 0.1 to 10%
Ashless, organic ester, anti-wear additives
0.02 to 5% 0.1 to 2.5%
and/or friction modifiers
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 ashless, organic
ester, anti-wear additives and/or friction 0.01 to 5 % 0.01 to 1.5 %
modifiers
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%
Corrosion and/or rust inhibitors other than
0.01 to 5 % 0.01 to 1.5%
boron-containing additives
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
T EP2015/080227
32
Lubricant Applications
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in any suitable non-aqueous lubricant compositions.
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in a lubricant composition which is a functional fluid, for example a
metalworking fluid. In at least some examples, this metalworking fluid is used to lubricate
metals during machining, rolling and the like.
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in a lubricant composition which is a power transmission fluid, for example 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. In at least some examples, the
lubricant composition is used in aviation lubricant applications.
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in a non-aqueous lubricant 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 Sulzer technical review
4/2009 pages 11-13.
In at least some examples, the boron-containing additives are used in a non-aqueous
lubricant 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. Typical ambient temperature is 20 °C, but in at least
some examples is less than 20°C, for example 0°C or lower.
Internal Combustion Engine Lubrication
In at least some examples, the boron-containing additives are used as inhibitors of
lead corrosion associated with ashless, organic ester, anti-wear additives and/or friction
modifiers in a lubricant composition which is used to lubricate an internal combustion
engine, for example as a crankcase lubricant. Examples of suitable engines include sparkignition,
internal combustion engines, and compression-ignition, internal combustion
engines. In at least some examples, the internal combustion engine is a spark-ignition
internal combustion engine used in automotive or aviation applications. Suitable internal
combustion engines include two-stroke compression-ignition engines and, in at least some
examples, the boron-containing additives are used as inhibitors of lead corrosion associated
with ashless, organic ester, anti-wear additives and/or friction modifiers in a system oil
lubricant composition and/or a cylinder oil lubricant composition used to lubricate the
engine. In at least some examples, the two-stroke compression-ignition engine is used in
marine applications.
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 labeled numerically as Example 1, Example 2, etc. and experiments not according to
the present invention are labeled alphabetically as Experiment A, Experiment B, etc.
Preparation of Lubricant Compositions.
A 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. The lubricant composition was made by admixing additives
as in a commercially available additive package containing dispersant, calcium sulphonate
and calcium phenate detergents, antioxidant, antifoam and ZDDP with Group I and III base
oils, a pour point depressant and a viscosity modifier.
A lubricant composition (Lubricant B) was prepared to model a lubricant
composition suitable for passenger cars with either compression-ignition or spark-ignition
internal combustion engines additionally comprising friction modifiers/anti-wear additives.
The lubricant composition was prepared generally as Lubricant A, but with the addition of
0.1% by weight of oleamide and 0.5% by weight of Citrem SP 70 (Trade Mark) (a
diglyceride of citric acid and oleic/linoleic acid).
A lubricant composition (Lubricant 1) according to the present invention was
prepared in the same way as Lubricant B, but with the addition of 1% of a borated
dispersant (Infmium C9230) (Trade Mark), specifically, a borated PIBSA-PAM dispersant.
A lubricant composition (Lubricant 2) according to the present invention was made
by admixing additives as in a commercially available additive package containing
dispersant, calcium sulphonate and calcium phenate detergents, antioxidant, antifoam and
ZDDP with Group III base oil, a pour point depressant, a viscosity modifier, a dispersant
viscosity modifier, 0.1% by weight of oleamide, 0.5% by weight of Citrem SP 70 (Trade
Mark) (a diglyceride of citric acid and oleic/linoleic acid) and a borated dispersant
(contained in additive package Hitec 9882B).
A lubricant composition (Lubricant C) was made by admixing additives as in a
commercially available additive package containing dispersant, calcium sulphonate and
calcium phenate detergents, antioxidant, antifoam and ZDDP with Group I and III base
oils, a pour point depressant, a viscosity modifier, 0.1% by weight of oleamide and 0.5%
by weight of Citrem SP 70 (Trade Mark) (a diglyceride of citric acid and oleic/linoleic
acid).
A lubricant composition (Lubricant 3) according to the present invention was
prepared in the same way as Lubricant C, but with the addition of 1% by weight of the
borated dispersant used in Lubricant 1 (Infmium C9230) (Trade Mark).
A lubricant composition (Lubricant D) was made by admixing additives as in a
commercially available additive package containing dispersant, calcium sulphonate and
calcium phenate detergents, antioxidant, antifoam and ZDDP with Group II and III base
oils, a pour point depressant, a viscosity modifier, a dispersant viscosity modifier, 0.1% by
weight of oleamide and 0.5% by weight of Citrem SP 70 (Trade Mark) (a diglyceride of
citric acid and oleic/linoleic acid).
A lubricant composition (Lubricant 4) according to the present invention was
prepared in the same way as Lubricant D, but with the addition of 1% by weight of the
borated dispersant used in Lubricant 1 (Infmium C9230) (Trade Mark).
A lubricant composition (Lubricant E) was prepared in the same way as Lubricant C,
but not including oleamide.
A lubricant composition (Lubricant 5) according to the present invention was
prepared in the same way as Lubricant E, but with the addition of 1% by weight of the
borated dispersant used in Lubricant 1 (Infinium C9230) (Trade Mark).
A lubricant composition (Lubricant F) was made by admixing additives as in a
commercially available additive package containing dispersant, calcium sulphonate and
calcium phenate detergents, antioxidant, antifoam and ZDDP with Group I and III base
oils, a pour point depressant, a viscosity modifier, 0.1% by weight of oleamide and 0.5%
by weight of Citrem SP 70 (Trade Mark) (a diglyceride of citric acid and oleic/linoleic
acid).
A lubricant composition (Lubricant 6) according to the present invention was
prepared in the same way as Lubricant F and using the same ingredients, but with the
addition of 0.5% by weight of the borated dispersant used in Lubricant 1 (Infmium C9230)
(Trade Mark).
A lubricant composition (Lubricant 7) according to the present invention was
prepared in the same way as Lubricant F, but with the addition of 0.33% by weight of tris-
2-ethylhexyl borate, CAS #2467-13-2 (Almabor) (Trade Mark).
A lubricant composition (Lubricant 8) according to the present invention was
prepared in the same way as Lubricant F, but with the addition of 1% by weight of tris-2-
ethylhexyl borate, CAS #2467-13-2 (Almabor) (Trade Mark).
A lubricant composition (Lubricant 9) according to the present invention was
prepared in the same way as Lubricant F, but with the addition of 0.66% by weight of an
additive pack comprising borated dispersant (Hitec 643D) (Trade Mark).
Lubricants A to F are not according to the present invention because the lubricant
compositions do not contain effective amounts of boron-containing additives. Lubricants 1
to 9 are according to the present invention.
Corrosion Testing of Lubricant Compositions.
1. Sequence VIII
Sequence VIII corrosion tests according to ASTM D6709-13 were undertaken for
Lubricants A and B as well as for Lubricants 1 and 2. The Sequence VIII test evaluates the
performance of a lubricant intended for use in spark-ignition gasoline engines for resisting
copper-, lead-, or tin-bearing corrosion. The test procedure is conducted using a
carbureted, spark-ignition Cooperative Lubrication Research (CLR) Oil Test Engine (also
referred to as the Sequence VIII test engine) run on unleaded fuel. The engine runs
continuously for 40 test hours at a test speed of 3,150 rpm. Oil temperature is raised to 143
°C (290 °F) using an external oil heater. The pass/fail criteria for the test include a
maximum bearing weight loss of 26.4 mg. There is a good correlation between Seq VIII
results and lead corrosion resistance in HTCBT bench tests.
The results for the tests are shown in Table 3. Experiment A is not according to the
present invention because the lubricant composition does not contain an effective amount
of boron-containing additives. Experiment B is not according to the present invention
because the lubricant composition does not contain an effective amount of boroncontaining
additives. Examples 1 and 2 are according to the present invention.
The results in Table 3 show that boron-containing additives, such as borated
dispersants, particularly borated polyisobutylene succinimide, for example Infinium C9230
(Trade Mark) are capable of mitigating the corrosive effects, particularly lead corrosion,
associated with the presence of an ashless, organic ester, anti-wear additive and/or friction
modifier, in particular a diglyceride of citric acid and an unsaturated C1 carboxylic acid
(e.g. oleic and/or linoleic acid), for example Citrem SP70 (Trade Mark).
Table 3
2. High Temperature Corrosion Bench Test (HTCBT)
High temperature Corrosion Bench Tests (HTCBT) according to ASTM D6594 were
undertaken for Lubricants C to F and Lubricants 3 to 9. HTCBT is intended to simulate
the corrosion process of non-ferrous metals in diesel lubricants and, in particular, is used to
determine the tendency of diesel engine lubricants to corrode alloys of lead and copper. In
the present test procedure, lead coupons are immersed in a measured amount of lubricant
oil. Air is passed through the lubricant oil at 135°C (275°F) for a period of time. Once the
test is complete, the coupons and stressed oil are examined to detect corrosion.
Concentrations of lead must be below defined levels to meet individual specification
requirements. For example, the "pass" limit for trucks is 100-120 ppm lead concentration
in the lubricant.
The results for the tests are shown in Table 4. Experiments C to F are not according
to the present invention because the lubricant compositions do not contain effective
amounts of boron-containing additives. Examples 3 to 9 are according to the present
invention.
The results in Table 4 show that boron-containing additives, such as a borated
dispersant, particularly borated polyisobutylene succinimide, for example Infinium C9230
(Trade Mark), and tris-2-ethylhexyl borate are capable of mitigating corrosive effects
associated with the presence of an ashless, organic ester, anti-wear additive and/or friction
modifier, 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).
Table 4
Total lead content of lubricant by
Total boron weight (ppm)
Borated content of
Lubricant
dispersant lubricant by
weight (ppm) Before HTCBT After HTCBT
test test
Expt. C C - 213 2 151
Infinium
Example 3 3 337 < 1 22
C9230
Expt. D D - 155 < 1 168
Infinium
Example 4 4 260 < 1 32
C9230
Expt. E E - 213 3 134
Infinium
Example 5 5 342 3 5 1 C9230
Expt. F F - 220 2 156
Infinium
Example 6 6 284 2 104
C9230
Example 7 7 Almabor 298 2 46
Example 8 8 Almabor 478 2 6
Borated
dispersant
in Hitec
Example 9 9 265 2 127
643D
additive
pack

Claims
1. The use of a boron-containing additive in a non-aqueous lubricant composition as an
inhibitor of lead corrosion associated with ashless, organic ester, anti-wear additives and/or
friction modifiers.
2. The use as claimed in claim 1, wherein the non-aqueous lubricant composition is
used to lubricate an internal combustion engine.
3. The use as claimed in claim 1 or claim 2, wherein the non-aqueous lubricant
composition comprises an ashless, organic ester, anti-wear additive and/or friction
modifier.
4. The use as claimed in claim 2, wherein an ashless, organic ester, anti-wear additive
and/or friction modifier is provided in a liquid fuel composition used to operate the internal
combustion engine, and a portion of said ashless, organic ester, anti-wear and/or friction
modifier ingresses into the non-aqueous lubricant composition during operation of said
engine.
5. The use as claimed in any one of the preceding claims, wherein the boron-containing
additive is a borated dispersant.
6. The use as claimed in claim 5, wherein the borated dispersant is a borated ester.
7. The use as claimed in claim 6, wherein the borated ester is a borated succinate ester
or a borated succinate ester amide.
8. The use as claimed in any one of the preceding claims wherein the ashless, organic
ester, anti-wear additive and/or friction modifier is
i) at least one fatty acid ester of a polyol,
ii) at least one oil-soluble mono, di-, or tri-glyceride of at least one hydroxy
polycarboxylic acid, or a derivative thereof;
iii) at least one long chain fatty acid ester of a hydroxy carboxylic acid in which
the long chain fatty acid has at least 4 carbon atoms and the ester is an oilsoluble
ester of a mono- or poly- hydroxy carboxylic acid containing 1 to 4
groups which are independently carboxylic acid groups or lower hydrocarbyl
esters thereof and in which, when the hydroxy carboxylic acid is a monohydroxy
carboxylic acid, the ester has a long chain fatty acid ester moiety of
the hydroxy group of the hydroxy carboxylic acid and, when the hydroxy
carboxylic acid is a poly-hydroxy carboxylic acid, the ester has independently
long chain fatty acid ester moieties of one or two of the hydroxy groups of the
poly-hydroxy carboxylic acid; or
iv) a mixture thereof
9. The use as claimed in claim 8, wherein the at least one fatty acid ester of a polyol is
an ester of a fatty acid containing 12 to 24 carbon atoms, preferably wherein the at least
one fatty acid ester of a polyol is glycerol mono-oleate, glycerol monostearate, glycerol
monolaurate, glycerol dodecanoate or glycerol octadodecanoate.
10. The use as claimed in claim 8, wherein the hydroxy polycarboxylic acid has at least
one hydroxy group which is in an alpha position with respect to a carboxylic moiety.
11. The use as claimed in claim 10, wherein the hydroxy polycarboxylic acid is citric
acid.
12. The use as claimed in any one of claims 8, 10 or 11, wherein the glyceride is a
glyceride of citric acid and oleic acid, a glyceride of citric acid and linoleic acid or a
mixture thereof.
13. The use as claimed in claim 8, wherein the oil-soluble ester has at least one long
chain fatty acid ester moiety in an alpha position with respect to a carboxylic acid group or
lower hydrocarbyl ester thereof.
14. The use as claimed in claim 8, wherein the oil-soluble ester is triethyl citrate butyrate,
triethyl citrate oleate, triethyl citrate octanoate, triethyl citrate myristate, diethyl tartrate
dibutyrate or diethyl tartrate dioleate.