The present invention relates to the field of lubricating compositions, in particular pertaining
to the fuel economy (FE or fuel eco) properties of the lubricating compositions and the
resistance to friction or abrasion. More specifically, the invention relates to a dinuclear
molybdenum complex for enhancing the fuel economy properties of a lubricating
composition comprising at least one base oil.
10
Developments in engines and the performance elements of lubricating compositions for
engines are inextricably linked. The conditions of use for gasoline and diesel engines
include both extremely short trips as well as long routes. Indeed, 80% of car trips in Western
Europe are less than 12 kilometers whereas annual mileage covered by vehicles goes up
15 to 300,000 km.
Lubricating compositions for motor vehicles should be adaptable to all of these conditions
of use and thus should have improved properties and performance characteristics.
Lubricating compositions for engines must therefore fulfill numerous objectives.
20 The lubrication of the parts that slide over one another plays a decisive role, in particular in
reducing the friction between these parts and consequently the wear and tear thereof, thus
in particular making it possible to save fuel.
An essential requirement of lubricating compositions for engines relates to environmental
aspects. It has indeed become essential to reduce fuel consumption in order to reduce CO2
25 emissions.
The nature of the lubricating compositions for motor vehicles has an impact on the fuel
consumption. Lubricating compositions for motor vehicles that help save fuel are often
referred to as fuel economy (FE) lubricants.
It is constantly sought to achieve improvement in the levels of FE (fuel eco) related
30 performance in the formulation of automotive lubricants.
To this end it is known practice to add friction modifiers such as organomolybdenum
compounds to lubricating compositions in order to lower the coefficient of friction. The
addition of such compounds in particular serves to enable fuel savings and thus confers the
lubricant with FE properties. When the engine is running, the organomolybdenum
35 compound forms in particular MoS2 (lamellar molybdenum disulphide) which allows friction
to be reduced.
2
Organomolybdenum compounds containing sulfur are fragile and can be degraded by
external chemical or thermal phenomena such as oxidation, hydrolysis, thermal
decomposition, and side reactions with other additives. The compounds or the degradation
products thereof may also precipitate and lose the Fuel Eco performance of the lubricating
5 composition (and therefore fuel savings) over time or cause cleanliness or corrosion related
problems.
In order to remedy this problem, it is possible to make use of organic friction modifiers which
are, however, less effective. An increase in the amount of organomolybdenum compound
has also been considered, however, this can lead to a risk of engine fouling and / or copper
10 corrosion as well as a significant increase in the cost of formulation of the lubricating
composition.
There is therefore a need to have lubricating compositions for engines, in particular for a
vehicle engine, which make it possible to provide a solution to all or part of the problems
15 faced with lubricating compositions of the state of the art. In particular, there is a need for a
stabilised organomolybdenum compound which does not present problems of precipitation
or degradation and loss of performance.
One objective of the present invention is to provide a stabilised molybdenum complex which
20 in particular does not present a problem of precipitation or degradation due to various
different external chemical or thermal phenomena.
Another objective of the present invention is also to provide a lubricating composition having
improved FE properties.
Another objective of the present invention is to provide a lubricating composition which
25 makes it possible to reduce the coefficient of friction.
Yet another objective of the present invention is to provide an organomolybdenum
compound that is less sensitive to various external chemical or thermal phenomena.
Still other objects will become apparent upon reading the description of the invention that
follows here below.
30
These objectives are fulfilled by the present invention which relates to a molybdenum
dinuclear complex with ligands selected from fatty tertiary amines having the formula (I):
(I)
in which:
35 R represents an alkyl, either linear or branched, comprising from 3 to 30 carbon atoms,
preferably from 3 to 20, advantageously from 7 to 17 carbon atoms;
3
n, being identical or different, represents 2 or 3;
R2 and R3
, being identical or different, represent a group: O, OR, NR'2, COOR', or COO,
where R’, being identical or different, represents a hydrogen atom or an alkali metal, or an
alkaline earth metal, preferably R’ is H, preferably R2 and R3 which are identical or different,
5 represent an OH or NH2 group.
Preferably, the compound having the formula (I) is selected from the following compounds:
R being as defined above.
10
The dinuclear complexes according to the present invention are complexes that comprise
two molybdenum atoms, each preferably having an octahedral structure, and being
complexed with a compound having the formula (I). Thus, the dinuclear complexes of the
present invention preferably correspond to the following formula (II):
15
in which R and n are as defined above and each of the (multiple) X, being identical or
different, represents O, OR, NR'2, COOR', or COO, where R’, being identical or different,
represents a hydrogen atom or an alkali metal or an alkaline earth metal; preferably R’ is
H; preferably X is OH or NH2
.
20
In a particularly advantageous manner, this complex does not contain sulfur.
4
Without intending to be bound by any theory, the presence of a ligand having the formula
(I) makes it possible to stabilise the molybdenum, or indeed even to protect the molybdenum
from various external chemical and thermal phenomena, and consequently to promote
sulfurisation with sulfur compounds present in the lubricant such as zinc dialkyl
5 dithiophosphate (DTPZn) for example.
Without intending to be bound by any theory, the complex according to the invention
effectively enables obtaining a low coefficient of friction, an improvement of the FE
properties of the lubricant and thereby achieve fuel savings.
10 The complexes according to the present invention are obtained by means of a method
comprising bringing about the reaction between a molybdenum compound and at least one
compound having the formula (I).
The molybdenum compound may be MoO3, an inorganic product containing molybdenum
such as ammonium molybdate, molybdenum chloride, molybdenum oxychloride, or an
15 organomolybdenum compound which according to the present invention, may be selected
from among organic molybdenum complexes comprising at least one molybdenum (Mo)
chemical element and at least one ligand such as a carboxylate ligand, an ester ligand, an
amide ligand, a dithiophosphate ligand, a dithiocarbamate ligand. The method corresponds
to a complexation of molybdenum with the compounds having the formula (I) according to
20 the invention by means of dissolution of an inorganic compound with formation of a complex
or by ligand exchange in the event of use of an organomolybdenum compound. For
example, the organic complexes of molybdenum with carboxylates, esters, and amides may
be obtained by bringing about the reaction of molybdenum oxide or ammonium molybdates
with fatty substances, glycerides, fatty acids or derivatives of fatty acids (esters, amines,
25 amides, etc). Within the meaning and scope of the invention, the carboxylate ligands, the
ester ligands and the amide ligands are free of sulfur and phosphorus.
In one embodiment, the organomolybdenum compound of the invention is selected from
molybdenum complexes with amide ligands, mainly prepared by bringing about the reaction
of a molybdenum source, which may be for example molybdenum trioxide, and an amine
30 derivative, and fatty acids comprising, for example, from 4 to 36 carbon atoms, such as, for
example, the fatty acids contained in plant oils or animal oils. The synthesis of such
compounds is for example described in the patents US4889647, EP0546357, US5412130
or EP1770153.
In one preferred embodiment of the invention, the organomolybdenum compound is
35 selected from among organic molybdenum complexes with amide ligands obtained by
bringing about the reaction:
5
(i) of a fatty substance of such type as mono, di or tri glyceride, or fatty acid;
(ii) of an amino source having the formula (A)
(A)
In which :
- X
1 5 represents an oxygen atom or a nitrogen atom;
- X
2
represents an oxygen atom or a nitrogen atom;
- n or m represents 1 when X1 or X2
respectively represents an oxygen atom;
- n or m represents 2 when X1 or X2
respectively represents a nitrogen atom;
(iii) and a molybdenum source selected from molybdenum trioxide or molybdates,
10 preferably ammonium molybdate.
In one embodiment of the invention, the organomolybdenum compound may comprise from
0.1 to 30% by weight, preferably from 0.1 to 20%, more preferentially from 2 to 8.5% by
weight of molybdenum relative to the total weight of the organomolybdenum complex.
Preferably, the organomolybdenum compound comprises at least one organic molybdenum
15 complex having the formula (III), (IV) or (V), alone or in a mixture:
(III)
in which :
X
1 represents an oxygen atom or a nitrogen atom;
X
2
represents an oxygen atom or a nitrogen atom;
n represents 1 when X1
represents an oxygen atom and m represents 1 when X2 20 represents
an oxygen atom;
n represents 2 when X1
represents a nitrogen atom and m represents 2 when X2
represents
a nitrogen atom;
6
R1 represents a linear or branched, saturated or unsaturated, alkyl group comprising from
4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms, advantageously from 6 to
18 carbon atoms;
(IV)
5 in which :
X
1 represents an oxygen atom or a nitrogen atom;
X
2
represents an oxygen atom or a nitrogen atom;
n represents 1 when X1 represents an oxygen atom and m represents 1 when X2
represents
an oxygen atom;
n represents 2 when X1
represents a nitrogen atom and m represents 2 when X2 10 represents
a nitrogen atom;
R1 represents a linear or branched, saturated or unsaturated, alkyl group comprising from
4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms, advantageously from 6 to
18 carbon atoms;
15 R2 represents a linear or branched, saturated or unsaturated, alkyl group comprising from
4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms, advantageously from 6 to
18 carbon atoms;
(V)
R1 represents a linear or branched, saturated or unsaturated, alkyl group comprising from
20 4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms, advantageously from 6 to
18 carbon atoms.
Advantageously, the organic molybdenum complex having the formula (III), (IV) or (V) is
prepared by bringing about the reaction:
(i) of a fatty substance of such type as mono, di or tri glyceride, or fatty acid;
25 (ii) of diethanolamine or 2-(2-aminoethyl) aminoethanol;
7
(iii) and a molybdenum source selected from molybdenum trioxide or
molybdates, preferentially ammonium molybdate.
More advantageously, the organic molybdenum complex having the formula (III) is
constituted of at least one compound having the formula (III-a) or (III-b), alone or in a
5 mixture:
(III-a)
in which R1 represents a linear or branched, saturated or unsaturated, alkyl group
comprising from 4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms,
advantageously from 6 to 18 carbon atoms;
10 (III-b)
in which R1 represents a linear or branched, saturated or unsaturated, alkyl group
comprising from 4 to 36 carbon atoms, preferentially from 4 to 20 carbon atoms,
advantageously from 6 to 18 carbon atoms.
As an example of molybdenum compounds that are sulfur-free according to the invention,
15 mention may be made of Molyvan 855® marketed by the company Vanderbilt.
In one other embodiment of the invention, the organomolybdenum compound is selected
from among organic molybdenum complexes with dithiophosphate ligands or organic
molybdenum complexes with dithiocarbamate ligands.
20 For the purposes of the invention, the organic molybdenum complexes with dithiophosphate
ligands are also known as molybdenum dithiophosphates or Mo-DTP compounds and
organic molybdenum complexes with dithiocarbamate ligands are also known as
molybdenum dithiocarbamates or Mo-DTC compounds.
In a more preferred embodiment of the invention, the organomolybdenum compound is
25 selected from molybdenum dithiocarbamates.
8
The Mo-DTC compounds are complexes formed from a metal nucleus of molybdenum
bound to one or more ligands, the ligand being an alkyl dithiocarbamate group. These
compounds are well known to the person skilled in the art.
In one embodiment of the invention, the Mo-DTC compound may comprise from 1 to 40%,
5 preferably from 2 to 30%, more preferentially from 3 to 28%, advantageously from 4 to 15%
by weight of molybdenum, relative to the total weight of the Mo-DTC compound.
In another embodiment of the invention, the Mo-DTC compound may comprise from 1 to
40%, preferably from 2 to 30%, more preferentially from 3 to 28%, advantageously from 4
to 15% by weight of sulfur, relative to the total weight of the Mo-DTC compound.
10 In another embodiment of the invention, the Mo-DTC compound may be selected from
among those wherein the nucleus has two molybdenum atoms (also known as dimeric MoDTCs) and those wherein the nucleus has three molybdenum atoms (also known as trimeric
Mo-DTCs).
In another embodiment of the invention, the trimeric Mo-DTC compounds correspond to the
15 formula Mo3SkLn in which:
k represents an integer at least equal to 4, preferably ranging from 4 to 10, advantageously
from 4 to 7;
n is an integer ranging from 1 to 4, and
L being an alkyl dithiocarbamate group comprising from 1 to 100 carbon atoms, preferably
20 from 1 to 40 carbon atoms, advantageously from 3 to 20 carbon atoms.
By way of examples of trimeric Mo-DTC compounds according to the invention, mention
may be made of the compounds and the methods of preparation thereof as described in
the documents WO 98/26030 and US 2003/022954.
25 In one preferred embodiment of the invention, the Mo-DTC compound is a dimeric Mo-DTC
compound.
By way of examples of dimeric Mo-DTC compounds, mention may be made of the
compounds and the methods of preparation thereof as described in documents EP
0757093, EP 0719851, EP 0743354 or EP 1013749.
30 The dimeric Mo-DTC compounds generally correspond to the compounds having the
formula (VI):
(VI)
9
in which:
R3, R4, R5, R6, being identical or different, independently represent a hydrocarbon group
selected from among alkyl, alkenyl, aryl, cycloalkyl or cycloalkenyl groups;
X3, X4, X5 and X6, being identical or different, independently represent an oxygen atom or a
5 sulfur atom.
Unless otherwise indicated, the term “alkyl group” within the meaning and scope of the
invention, and in particular for R3, R4, R5 and R6 having the formula (VI), is understood to
refer to a hydrocarbon group, either linear or branched, saturated or unsaturated,
comprising from 1 to 24 carbon atoms, preferably from 4 to 18 carbon atoms.
10 In one embodiment of the invention, the alkyl group is selected from the group formed by
methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, iso-pentyl, neopentyl,
hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl,
hexadecyl, stearyl, icosyl, docosyl, tetracosyl, triacontyl, 2-ethylhexyl, 2-butyloctyl, 2-
butyldecyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldodecyl, 2-octyldodecyl, 2-
15 decyltetradecyl, 2-dodecylhexadecyl, 2-hexadecyloctadecyl, 2-tetradecyloctadecyl,
myristyl, palmityl and stearyl.
The term “alkenyl group” within the meaning and scope of the present invention is
understood to refer to a linear or branched hydrocarbon group comprising at least one
double bond and comprising from 2 to 24 carbon atoms. The alkenyl group may be selected
20 from among vinyl, allyl, propenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl,
heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl and oleic.
Within the meaning and scope of the present invention, the term “aryl group” is understood
to refer to a polycyclic aromatic hydrocarbon or an aromatic group, whether or not
substituted by an alkyl group. The aryl group may contain from 6 to 24 carbon atoms.
25 In one embodiment, the aryl group may be selected from among the group formed by
phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl,
ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl,
octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, phenylphenyl,
benzylphenyl, phenyl-styrene, p-cumylphenyl and naphthyl.
30 Within the meaning and scope of the present invention, the term “cycloalkyl group” is
understood to refer to a polycyclic or cyclic hydrocarbon, whether or not substituted by an
alkyl group.
Within the meaning and scope of the present invention, the term “cycloalkenyl group” is
understood to refer to a polycyclic or cyclic hydrocarbon, whether or not substituted by an
35 alkyl group, and comprising at least one unsaturation.
10
The cycloalkyl groups and the cycloalkenyl groups may comprise from 3 to 24 carbon
atoms.
Within the meaning and scope of the present invention, the cycloalkyl groups and the
cycloalkenyl groups may be selected, in a nonlimiting manner, from the group constituted
5 of cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl,
methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl,
methylcyclohexenyl.
In one preferred embodiment of the invention, R3, R4, R5 and R6 having the formula (VI),
being identical or different, independently represent an alkyl group comprising from 1 to 24
10 carbon atoms, preferably from 4 to 18 carbon atoms, or an alkenyl group comprising from
2 to 24 carbon atoms.
In one embodiment of the invention, X3, X4, X5 and X6 may be identical and may represent
a sulfur atom.
In one other embodiment of the invention, X3, X4, X5 and X6 may be identical and may be
15 an oxygen atom.
In one other embodiment of the invention, X3 and X4 may represent a sulfur atom, and X5
and X6 may represent an oxygen atom.
In one other embodiment of the invention, X3 and X4 may represent an oxygen atom, and
X5 and X6 may represent a sulfur atom.
20
In one other embodiment of the invention, the ratio of the number of sulfur atoms to the
number of oxygen atoms (S/O) of the Mo-DTC compound can vary from (1/3) to ( 3/1).
In one other embodiment of the invention, the Mo-DTC compound having the formula (VI)
may be selected from a symmetrical Mo-DTC compound, an asymmetrical Mo-DTC
25 compound and a combination thereof.
The term “symmetrical Mo-DTC compound” according to the invention is understood to refer
to an Mo-DTC compound having the formula (VI) in which the groups R3, R4, R5 and R6 are
identical.
The term “asymmetrical Mo-DTC compound” according to the invention is understood to
30 refer to an Mo-DTC compound having the formula (VI) in which the R3 and R4 groups are
identical, the R5 and R6 groups are identical, and the R3 and R4 groups are different from
the R5 and R6 groups.
In one preferred embodiment of the invention, the Mo-DTC compound is a mixture of at
least one symmetrical Mo-DTC compound and at least one asymmetrical Mo-DTC
35 compound.
11
In one embodiment of the invention, R3 and R4 having the formula (VI), which are identical,
represent an alkyl group comprising from 5 to 15 carbon atoms, preferably from 8 to 13
carbon atoms, and R5 and R6 having the formula (VI), which are identical, represent an alkyl
group comprising from 5 to 15 carbon atoms, preferably from 8 to 13 carbon atoms, and the
5 groups R3 and R4 having the formula (VI), are identical or different from the groups R5 and
R6 having the formula (VI).
In another preferred embodiment of the invention, R3 and R4 having the formula (VI), which
are identical, represent an alkyl group comprising from 6 to 10 carbon atoms, and R5 and
R6 having the formula (VI), which are identical, represent an alkyl group comprising from 10
to 15 carbon atoms, and the groups R3 10 and R4 having the formula (VI) are different from the
groups R5 and R6 having the formula (VI).
In one other preferred embodiment of the invention, R3 and R4 having the formula (VI),
which are identical, represent an alkyl group comprising from 10 to 15 carbon atoms, and
R5 and R6 having the formula (VI), which are identical, represent an alkyl group comprising
from 6 to 10 carbon atoms, and the groups R3 15 and R4 having the formula (VI) are different
from the groups R5 and R6 having the formula (VI).
In one other preferred embodiment of the invention, R3, R4, R5 and R6, which are identical,
represent an alkyl group comprising from 5 to 15 carbon atoms, preferably from 8 to 13
carbon atoms.
20 In an advantageous manner, the Mo-DTC compound is selected from among the
compounds having the formula (V) in which:
- X3 and X4 represent an oxygen atom;
- X5 and X6 represent a sulfur atom;
- R3 having the formula (VI) represents an alkyl group comprising 8 carbon atoms or an alkyl
25 group comprising 13 carbon atoms;
- R4 having the formula (VI) represents an alkyl group comprising 8 carbon atoms or an alkyl
group comprising 13 carbon atoms;
- R5 having the formula (VI) represents an alkyl group comprising 8 carbon atoms or an alkyl
group comprising 13 carbon atoms;
30 - R6 having the formula (VI) represents an alkyl group comprising 8 carbon atoms or an alkyl
group comprising 13 carbon atoms.
Thus, in an advantageous manner, the Mo-DTC compound is selected from among the
compounds having the formula (Vl-a)
12
in which the groups R3, R4, R5 and R6 are as defined for the formula (V).
in a more advantageous manner, the Mo-DTC compound is a mixture:
- of an Mo-DTC compound having the formula (Vl-a) in which R3, R4, R5 and R6 represent
5 an alkyl group comprising 8 carbon atoms;
- of an Mo-DTC compound having the formula (Vl-a) in which R3, R4, R5 and R6 represent
an alkyl group comprising 13 carbon atoms, and/or
- of an Mo-DTC compound having the formula (VI-a) in which R3
, R4 represent an alkyl
group comprising 8 carbon atoms and R5 and R6 represent an alkyl group comprising 13
10 carbon atoms.
By way of examples of Mo-DTC compounds, mention may be made of the products Molyvan
L®, Molyvan 807®, or Molyvan 822® marketed by the firm R. T Vanderbilt Compagny®, or
the products Sakura-lube 200®, Sakura-lube 165®, Sakura-lube 525® or Sakura-lube
600® marketed by the company Adeka.
15
Preferably, the molybdenum complex preparation method for preparing the dinuclear
complex according to the invention is carried out at a temperature of between 0°C and
250°C, preferably between 20 and 150°C, preferably at ambient temperature, for example
between 15 and 30°C.
20 Preferably, the N/Mo atomic ratio in the mixture of the method of the invention is between
1 and 50, preferably between 2 and 10.
Preferably the method is carried out in the presence of water. Without intending to be bound
by any theory, water in an advantageous manner, will play a role as catalyst. Preferably,
the molar ratio between water and the compound having the formula (I) is comprised
25 between 0.5 and 10.
The present invention also relates to a lubricating composition comprising:
- at least one base oil;
- at least one dinuclear molybdenum complex according to the invention.
30 Preferably, the lubricating composition according to the invention comprises from 0.001 to
0.1% by weight of dinuclear molybdenum complex according to the invention, relative to the
total weight of the composition.
13
In a general manner, the lubricating composition according to the invention may comprise
any type of mineral, synthetic or natural, animal or plant lubricating base oil known to the
person skilled in the art.
The base oils used in the lubricating compositions according to the invention may be oils of
5 mineral or synthetic origins belonging to groups I to V according to the classes defined in
the American Petroleum Institute (API) classification (or equivalents thereof according to
the ATIEL (Technical Association of the European Lubricants Industry) classification) (Table
1) or the mixtures thereof.
[Table 1]
10
Saturates content Sulfur content Viscosity index
(VI)
Group 1
Mineral oils
<90% >0.03% 80 ≤ VI< 120
Group II
Hydrocracked oils
≥90% ≤0.03% 80 ≤ VI< 120
Group Ill
Hydrocracked or
hydroisomerised oils
≥90% ≤0.03% ≥ 120
Group IV Poly-alpha-olefins (PAO)
Group V Esters and other bases not included in groups I to IV
The mineral base oils according to the invention include all types of base oils obtained by
atmospheric and vacuum distillation of crude oil, followed by refining operations such as
15 solvent extraction, deasphalting, solvent dewaxing, hydrotreatment, hydrocracking,
hydroisomerisation.
Mixtures of synthetic and mineral oils may also be used.
There is generally no limitation as to the use of different lubricating bases in order to produce
the lubricating compositions according to the invention, except that they should have
20 properties - in particular in respect of viscosity, viscosity index, sulfur content, resistance to
oxidation - that are suitable for use in engines or for vehicle transmissions.
The base oils of the lubricating compositions according to the invention may also be
selected from among synthetic oils, such as certain esters of carboxylic acids and alcohols,
and from polyalphaolefins. The polyalphaolefins used as base oils are for example obtained
25 from monomers comprising from 4 to 32 carbon atoms, for example from decene, octene
or dodecene, and of which the viscosity at 100°C is between 1.5 and 15 mm2
.s
1 according
to the standard ASTM D445 [from ASTM International, formerly American Society for
Testing and Materials). Their average molecular weight is generally between 250 and 3000
according to the standard ASTM D5296.
14
In a preferred manner, the base oils of the present invention are selected from the above
base oils wherein the aromatics content is between 0 and 45%, preferably between 0 and
30%. The aromatics content of oils is measured according to the Burdett UV method.
Without intending to be bound by any theory, the aromaticity of the base oil is a
5 characteristic that serves to optimise the functioning of the polymer as a function of
temperature. The choice of an aromatic-lean oil makes possible an optimum at a higher
temperature.
In an advantageous manner, the lubricating composition according to the invention
comprises at least 50% by weight of base oils relative to the total weight of the composition.
10 In a more advantageous manner, the lubricating composition according to the invention
comprises at least 60% by weight, or even at least 70% by weight, of base oils relative to
the total weight of the composition.
In a particularly more advantageous manner, the lubricating composition according to the
invention comprises from 60 to 99.5% by weight of base oils, preferably from 70 to 99.5%
15 by weight of base oils, relative to the total weight of the composition.
Many additional additives may be used for this lubricating composition according to the
invention.
The preferred additional additives for the lubricating composition according to the invention
20 are selected from among detergent additives, anti-wear additives, friction modifying
additives other than organomolybdenum compounds, extreme pressure additives,
dispersants, pour point improvers, anti-foaming agents, thickeners and mixtures thereof.
In a preferred manner, the lubricating composition according to the invention comprises at
least one anti-wear additive, at least one extreme pressure additive or mixtures thereof.
25 The anti-wear additives and extreme pressure additives protect surfaces in frictional contact
by forming a protective film that is adsorbed on these surfaces.
There exists a wide variety of anti-wear additives. In a preferred manner, for the lubricating
composition according to the invention, the anti-wear additives are selected from sulfurphosphorus additives such as metal alkylthiophosphates, in particular zinc
30 alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP. The
preferred compounds are those having the formula Zn((SP(S)(OR1
)(OR2
))2, in which R1 and
R2
, being identical or different, independently represent an alkyl group, preferentially an
alkyl group comprising from 1 to 18 carbon atoms.
Amine phosphates are also anti-wear additives that may be used in the lubricating
35 composition according to the invention. However, the phosphorus provided by these
additives can act as a poison for catalytic systems in automobiles because these additives
15
are ash-generating. These effects can be minimised by partially substituting the amino
phosphates with additives which do not provide phosphorus, such as, for example,
polysulfides, in particular sulfur-containing olefins.
In an advantageous manner, the lubricating composition according to the invention may
5 comprise from 0.01 to 6% by weight, preferably from 0.05 to 4% by weight, more
preferentially from 0.1 to 2% by weight, relative to the total weight of the lubricating
composition, anti-wear additives and extreme pressure additives.
In an advantageous manner, the lubricating composition according to the invention may
comprise at least one additional friction modifier additive other than the organomolybdenum
10 compounds. The additional friction modifier additive may be selected from a compound
providing metallic elements and an ash-free compound. Among the compounds providing
metallic elements, mention may be made of complexes of transition metals such as Sb, Sn,
Fe, Cu, Zn, whereof the ligands may be hydrocarbon compounds comprising atoms of
oxygen, nitrogen, sulfur or phosphorus. The ash-free, friction modifier additives are
15 generally of organic origin and may be selected from among monoesters of fatty acids and
polyols, fatty epoxides, borate fatty epoxides; or fatty acid glycerol esters. According to the
invention, the fatty compounds comprise at least one hydrocarbon group comprising from
10 to 24 carbon atoms.
In an advantageous manner, the lubricating composition according to the invention may
20 comprise at least one antioxidant additive.
The antioxidant additive generally makes it possible to delay the degradation of the
lubricating composition in use. This degradation in particular may be reflected in the
resulting formation of deposits, in the presence of sludge or slurry, or in an increase in the
viscosity of the lubricating composition.
25 Antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers.
Among the antioxidant additives commonly used, mention may be made of various types
such as phenolic antioxidant additives, amine antioxidant additives, and sulfur-phosphorus
antioxidant additives. Some of these antioxidant additives, for example sulfur-phosphorus
antioxidant additives, can be ash-generating. The phenolic antioxidant additives may be
30 ash-free or indeed even be in the form of basic or neutral metal salts. The antioxidant
additives in particular may be selected from among sterically hindered phenols, sterically
hindered phenolic esters and sterically hindered phenols comprising a thioether bridge,
diphenylamines, diphenylamines substituted with at least one C1-C12 alkyl group, N,N'-
dialkyl-aryl-diamines and mixtures thereof.
35 Preferably according to the invention, the sterically hindered phenols are selected from
compounds comprising a phenol group of which at least one vicinal carbon of the carbon
16
bearing the alcohol functional group is substituted by at least one C1-C10 alkyl group,
preferably a C1-C6 alkyl group, preferably a C4 alkyl group, preferably by the tert-butyl group.
Amino compounds are another class of antioxidant additives that may be used, possibly in
combination with phenolic antioxidant additives. Examples of amino compounds are
aromatic amines, for example aromatic amines having the formula NR7R8R9
in which R7 5
represents an aliphatic group or an aromatic group, optionally substituted, R8
represents an
aromatic group, optionally substituted, R9
represents a hydrogen atom, an alkyl group, an
aryl group, or a group of having the formula R10S(O)zR11 in which R10 represents an alkylene
group or an alkenylene group, R11 represents an alkyl group, an alkenyl group, or an aryl
10 group, and z represents 0, 1 or 2.
Sulfurised alkyl phenols or the alkali and alkaline earth metal salts thereof may also be used
as antioxidant additives.
The lubricating composition according to the invention may contain all types of antioxidant
additives known to the person skilled in the art.
15 In an advantageous manner, the lubricating composition comprises at least one ash free
antioxidant additive.
In an equally advantageous manner, the lubricating composition according to the invention
comprises from 0.5 to 2% by weight, relative to the total weight of the composition, of at
least one antioxidant additive.
20 The lubricating composition according to the invention may also comprise at least one
detergent additive.
Detergent additives generally serve to reduce the formation of varnish on the surface of
metal parts by dissolving the by-products of oxidation and combustion.
The detergent additives that may be used in the lubricating composition according to the
25 invention are generally known to the person skilled in the art. The detergent additives may
be anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic
head. The associated cation may be a metal cation of an alkali metal, or an alkaline earth
metal.
The detergent additives are preferentially selected from among alkali metal or alkaline earth
30 metal salts of carboxylic acids, sulphonates, salicylates, naphthenates, as well as salts of
phenates. The alkali metals and alkaline earth metals are preferentially calcium,
magnesium, sodium or barium.
These metal salts generally comprise the metal in a stoichiometric quantity or else indeed
in excess, therefore in an amount greater than the stoichiometric quantity. These are thus
35 then overbased detergent additives; the excess metal that contributes the overbased
character to the detergent additive is then generally in the form of a metal salt that is
17
insoluble in oil, for example a carbonate, a hydroxide, an oxalate, an acetate, a glutamate,
preferentially a carbonate .
In an advantageous manner, the lubricating composition according to the invention may
comprise from 2 to 4% by weight of detergent additive relative to the total weight of the
5 lubricating composition.
In an equally advantageous manner, the lubricating composition according to the invention
may also comprise at least one pour point depressant additive.
By slowing the formation of paraffin crystals, the pour point depressant additives generally
improve the low-temperature behaviour of the lubricating composition according to the
10 invention.
By way of examples of pour point depressant additives, mention may be made of polyalkyl
methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes,
alkylated polystyrenes.
In an advantageous manner, the lubricating composition according to the invention may
15 also comprise at least one dispersing agent.
The dispersing agent may be selected from among Mannich bases, succinimides and
derivatives thereof.
In an equally advantageous manner, the lubricating composition according to the invention
may comprise from 0.2 to 10% by weight of dispersing agent relative to the total weight of
20 the lubricating composition.
The lubricating composition of the present invention may also include at least one additional
polymer that improves the viscosity index. By way of examples of additional polymers that
improve the viscosity index, mention may be made of polymer esters, homopolymers or
copolymers, either hydrogenated or non-hydrogenated, of styrene, butadiene and isoprene,
25 polymethacrylates (PMA).
The lubricating composition according to the invention preferably comprises in addition at
least one anti-wear additive, for example ZnDTP (zinc dithiophosphate).
30 The present invention also relates to a lubrication method for lubricating an engine, in
particular an internal combustion engine, the method including the lubrication of component
parts of the engine with the lubricating composition of the invention.
The present invention also relates to the use of a compound having the formula (I) for
35 protecting molybdenum, from degradation thereof in the lubricating composition, in
particular for stabilising the molybdenum.
18
The present invention also relates to the use of the dinuclear molybdenum complex
according to the invention in a lubricating composition comprising at least one base oil, for
enhancing the Fuel Eco properties of the lubricating composition and maintaining them over
time. Preferably, the dinuclear molybdenum complex according to the invention is used in
5 implementation in an amount ranging from 100 ppm to 1000 ppm molybdenum, preferably
400 to 800 ppm molybdenum, by weight relative to the total weight of the lubricating
composition.
The present invention also relates to a molybdenum protection method, in particular by
10 means of hydrolysis, for protecting the molybdenum in a lubricating composition comprising
at least one base oil, from degradation, the method comprising of the complexation of the
said molybdenum in the form of a dinuclear complex with at least one compound having the
formula (I) according to the invention.
15 The present invention also relates to a Fuel Eco enhancing method for enhancing the Fuel
Eco properties of a lubricating composition comprising at least one base oil, the method
comprising of the addition, in the said lubricating composition, of a dinuclear complex
according to invention. Preferably, the dinuclear molybdenum complex according to the
invention is used in implementation in an amount ranging from 100 ppm to 1000 ppm
20 molybdenum, preferably from 400 to 800 ppm molybdenum, by weight relative to the total
weight of the lubricating composition.
Thus, and in a particularly advantageous manner, the use in implementation of the dinuclear
molybdenum complex according to the invention makes possible the prolongation over time
25 of the properties of the organomolybdenum compound, in particular as a lubricating agent,
preferably as a friction modifier.
In a particularly advantageous manner, the compositions of the invention comprising the
complex of the invention exhibit a low coefficient of friction which is maintained over time.
30 The particular, advantageous or preferred characteristic features of the combined use
according to the invention define the particular, advantageous or preferred combinations
that may be used according to the invention.
Figure 1 provides the molbdenum content for compositions according to the invention and
35 for comparative compositions after 1 month.
19
The present application will be described here below with the aid of non-limiting examples.
Example 1: Preparation of Dinuclear Molybdenum Complexes
The dinuclear molybdenum complexes are obtained by mixing MoO3 with the following
5 amines at ambient temperature for a period of 2 weeks. The weight of amine used in
implementation is equal to 3x (0.5/n)%, with n corresponding to the number of nitrogen in
the molecule.
[Table 2]
Example 1.1 (comparative) Duomeen CD (N-Coco-1,3-
diaminopropane. N-cocoalkyl-1,3-
diaminopropane)
Example 1.2 (comparative) Triameen T (N-tallow alkyldipropylene
triamine)
Example 1.3 (invention) Stearyldiethanolamine
Example 1.4 (invention) Triameen YT (N tallow alkyl dipropylene
branched triamine)
10 The lubricating compositions are then produced from each of the complexes obtained by
mixing a base oil of the type Poly-alpha-olefin (PAO), with the complex (in a manner so as
to have 400 ppm of Mo in the lubricating composition) and 1% by weight of ZnDTP. The
mixture is heated for 30 min at 60°C.
15 Example 2: Impact of the Ligand on the Stability of Molybdenum
The lubricating compositions obtained in Example 1 were stored over a period of several
months in order to assess their stability.
The quantity of Mo was measured after 1 month, the results are provided in Figure 1 which
clearly shows the stability of the compositions of the invention as compared to the
20 comparative compositions.
Example 3: Study of the Coefficient of Friction as a Function of Time
The tests were carried out, for each of the compositions of Example 1, on a tribometer with
a ball (Ø 12 mm)-plane contact, both made of 100C6 steel. The conditions used for these
25 tests are as follows: a normal load of 7N, which corresponds to a maximum contact pressure
of 540 MPa, a temperature of 110°C, a speed of 5 Hz, an amplitude of 5 mm. 5 A/R cycles
are performed in 1 s, which corresponds to 18,000 cycles per hour.
The results of the coefficient of friction for 10,000 cycles are as follows:
20
Example 1.1: 0.045
Example 1.2: 0.045
Example 1.3: 0.04
Example 1.4: 0.03
5
These results show a reduction in the coefficient of friction by the compositions of the
invention. This low coefficient of friction is maintained over time.

We Claim:

1. A molybdenum dinuclear complex with ligands selected from fatty tertiary
amines having the formula (I):
5 (I)
in which:
R represents an alkyl, either linear or branched, comprising from 3 to 30 carbon
atoms, preferably from 3 to 20, advantageously from 7 to 17 carbon atoms;
n, being identical or different, represents 2 or 3;
R2 and R3 10 , being identical or different, represent a group: O, OR, NR'2, COOR',
or COO, where R’, being identical or different, represents a hydrogen atom or an alkali
metal, or an alkaline earth metal, preferably R’ is H, preferably R2 and R3 which are
identical or different, represent an OH or NH2 group.
15 2. A complex according to claim 1, in which the compound having the formula
(I) is selected from the following compounds:
R being as defined in claim 1.
20 3. A complex according to claim 1 that corresponds to the formula (II):
22
in which R and n are as defined above and each of the (multiple) X, being
identical or different, represents O, OR, NR'2, COOR', or COO, where R’, being
identical or different, represents a hydrogen atom or an alkali metal or an alkaline
earth metal; preferably R’ is H; preferably X is OH or NH2
.
5
4. A molybdenum complex preparation method for preparing a complex
according to one of claims 1 to 3 comprising the mixing of a molybdenum compound
and a compound having the formula (I).
10 5. A lubricating composition comprising:
- at least one base oil;
- at least one dinuclear molybdenum complex according to any one of claims 1
to 3.
15 6. A lubricating composition according to claim 5 that further comprises at least
one anti-wear additive, for example zinc dithiophosphate (ZnDTP).
7. A lubricating composition according to claims 5 or 6 comprising from 0.001
to 0.1% by weight of dinuclear molybdenum complex according to any one of claims
20 1 to 3, relative to the total weight of the composition.
8. The use of a complex according to any one of claims 1 to 3 in a lubricating
composition comprising at least one base oil for lowering the coefficient of friction of
the lubricating composition, and preferably for maintaining a low coefficient of friction
25 over time.
9. The use of a compound having the formula (I)
in which:
30 R represents an alkyl, either linear or branched, comprising from 3 to 30 carbon
atoms, preferably from 3 to 20, advantageously from 7 to 17 carbon atoms;
n, being identical or different, represents 2 or 3;
R2 and R3
, being identical or different, represent a group: O, OR, NR'2, COOR',
or COO, where R’, being identical or different, represents a hydrogen atom or an alkali
23
metal, or an alkaline earth metal, preferably R’ is H, preferably R2 and R3 which are
identical or different, represent an OH or NH2 group.
for stabilising the molybdenum in a lubricating composition.
5 10. The use of a lubricating composition according to one of claims 5 to 7 for
lubricating an engine, in particular an internal combustion engine.
11. A molybdenum protection method, in particular by means of hydrolysis,
for protecting the molybdenum in a lubricating composition comprising at least one
10 base oil, from degradation, the method comprising of the complexation of the said
molybdenum in the form of a dinuclear complex with at least one compound having
the formula (I):
in which:
15 R represents an alkyl, either linear or branched, comprising from 3 to 30 carbon
atoms, preferably from 3 to 20, advantageously from 7 to 17 carbon atoms;
n, being identical or different, represents 2 or 3;
R2 and R3
, being identical or different, represent a group: O, OR, NR'2, COOR',
or COO, where R’, being identical or different, represents a hydrogen atom or an alkali
metal, or an alkaline earth metal, preferably R’ is H, preferably R2 20 and R3 which are
identical or different, represent an OH or NH2 group.
12. A Fuel Eco enhancing method for enhancing the Fuel Eco properties of
a lubricating composition comprising at least one base oil, the method comprising of
25 the addition, in the said lubricating composition, of a dinuclear complex according to
any one of claims 1 to 3.
13. A method according to claim 12, wherein the dinuclear molybdenum
complex is used in implementation in an amount ranging from 100 ppm to 1000 ppm
30 molybdenum, preferably from 400 to 800 ppm molybdenum, by weight relative to the
total weight of the lubricating composition.