Lubricant composition
Field of the invention
The present invention relates to a lubricant composition comprising at least two glycerol
esters. This combination of two glycerol esters makes it possible to obtain a lubricant
composition having a very low friction coefficient. Use of this lubricant composition
promotes he1 savings. It can in particular be used for lubricating the engines of light vellicles,
heavy goods vehicles (HGV) or ships.
Technological background of the invention
Because of environmental concerns, there are increasing efforts to reduce polluting
emissions and achieve &el savings in vehicles. The nature of the engine lubricant has an
influence on these two phenomena.
The behaviour of the lubricant in the reduction of fiction has an impact on fuel
consumption. It is mainly the quality of the base oils, alone or in combination with polymers
improving the viscosity index (VI) and friction modifying (FM) additives, that gives the
lubricant its " ~ u eEic o" (FE) properties.
Among the fiiction modifiers used conventionally, molybdenum dialkyldithiocarbamate
(or Mo-DTC), which is an inorganic friction modifier, and glycerol monooleate (or GMO),
which is an organic friction modifier may be mentioned. GMO, in contrast to Mo-DTC, is a
friction modifier which has the advantages that it does not contain ash, phosphorus or sulphur
and is produced from raw materials of renewable origin. However, its friction properties are
not as good as those of Mo-DTC, for example.
It would therefore be desirable to be able to formulate lubricant compositions with
fiiction modifiers obtained from compounds originating from raw materials of renewable
origin, not comprising ash, having improved friction properties relative to lubricant
compositions comprising GMO.
The use of a mixture of esters for reducing friction in engines is known from the
documents US2005/075254 and W02005/030912. These' esters are obtained liom an
esterification reaction between a. polyol and a cyclic fatty acid comprising from 1.2 to 28
30 carbon atoms andlor a branched fatty acid comprising from 12 to 28 carbon atoms.
The document US2008/176778 describes a lubricant composition in the form of an
emulsion. This composition in particular comprises a lipophilic compound and an emulsifier.
The lipophilic compound can in particular be selected from, caprylate or caprate triglycerides
and the emulsifying compound can in particular be glycerol monooleate.
The document US5064546 describes a lubricant composition comprising a base oi.1 and
a friction modifier, which can be a coconut oil.
The document JP2005082709 describes a method for reducing friction in engines using
a lubricant composition comprising at least an glycerol ester. These esters are obtained from
5 carboxylic acids comprising from 10 to 18 carbon atoms.
The document US2005/070450 describes lubricant compositions comprising a product
obtained by a transesterification reaction between an ester of glycerol and an ester of polyo1
different from glycerol.
The present invention therefore relates to lubricant compositions in particular for
10 engines, comprising at least two glycerol esters with different chemical natures. The
combination of these two glycerol esters of different chemical.natures makes it poss:ible to
obtain good performance in terns of fiiction and in teims of fuel economy.
Summary of the invention
A subject of the present invention is lubricant compositions in particular for engines,
15 comprising at least two friction modifier additives not supplying any sulphated ash, sulphur or
phosphorus; these additives replace, totally or partially, the conventional additives used in'this
type of application, such as molybdenum dialkyldithiocarbamate or glycerol monooleate.
Moreover, these fiiction modifying additives that do not supply any sulphated .ash, in
combination with one another, allow said lubricant compositions to retain optimum properties
20 , in terms of he1 economy (also called Fuel Eco) while having a 'low or very low level of
sulphated ash, sulphur, and phosphorus. The compositions according to the invention are?
lubricant compositions in particular for engines comprising: 1 :
a) at least onc base oil,
b) at least one ester of glycerol and of a Clz to Cza carboxylic acid, denoted. El,
25 C) at least one ester of glycerol and of a C4 to CIOca rboxylic-acid, denoted E2. J
In an embodiment of the invention, the lubricant composition-can comprise at 11:ast one
base oil and at least two glycerol esters El and E2, glycerol ester El being an ester of glycerol
and of a Cl2to CZbc arboxylic acid, and glycerol ester E2 being an ester of glycerol ancl of a Cq
to Cloca rboxylic acid, said ester El is a mixture of glycerol monoesters, glycerol diesters,
30 glycerol triesters and free glycerol and said ester E2 .is a mixture of glycerol monocsters,
glycerol diesters, glycerol triesters and free glycerol.
Advantageously, the lubricant compositions of the invention allow he1 savings to be
made during the phase of engine starting relative to the lubricant compositions colnprising
Thus, a subject of the invention is a lubricant composition comprising at least one base
oil and at least two glycerol esters El and E2, glycerol ester El being an ester of glycercll and
of a Clz to Cza carboxylic acid, and glycerol ester E2 being an ester of glycerol and of a Cq to
Clo carboxylic acid.
5 In a variant of the invention, the glycerol esters El and E2 are selected independently
from the glycerol monoesters, diesters, and triesters and mixtures thereof
In a variant of the invention, the carboxylic acids of the glycerol esters El and E2 are
saturated or unsaturated, linear or branched carboxylic acids, optionally substituted. with
hydroxyl andor epoxide groups.
10 In a variant of the invention, the lubricant composition can also comprise glycerol.
In a variant of the invention, glycerol ester El is an ester of glycerol a@ of a CI4 1:o C24,
preferably C16 to C22, more.preferably C18 to carboxylic acid.
In a variant of the invention, glycerol ester El is an ester of glycerol and of a C12 to C26
carboxylic acid, the hydrocarbon chain of the carboxylic 'acid comprising at least two
15 unsaturations.
In a variant of the invention, glycerol ester E2 is an ester of glycerol and of a Cs to C9,
preferably C6 to C8, more preferably C7 carboxylic acid.
i
In a variant of the invention, glycerol ester El is selected from the glycerol 1in.oleates ,
f
and mixtures thereof, and glycerol ester E2 is selected from the glycerol .heptanoates and
20 mixtures thereof.
In a variant of the invention, the sum of the masses of the glycerol esters El and :E2, and
optionally of the glycerol, represents 0.1 to 5% by mass, relative to the total mass of the
lubricant composition, preferably from 0.2 to 4%, more preferably from 0.5 to 3%, even more
i preferably from 1 to 2%.
In a variant of the invention, the mass ratio of the glycerol ester(s) El to the glycerol
ester(s) E2 is comprised between 10: 1 and 1 : 10, preferably between .5:l and 1 :5, more
preferably between 2: 1 and 1 :2, and even more preferably is equal to 1 : 1.
In a variant of the invention, the lubricant composition can have a level of sulphated ash
less than or equal to 0.8% meas'wed according to the standard ASTM D874, preferably less
than or equal to 0.5%. !
2 '
In a variant of the invention, the lubricant composition can have a level of phosphorus
less than or equal to 900.ppm measured according to the standbd ASTM D5 185, preferably
less than or equal to 500 ppm.
In 'a variant of the invention, the lubricant composition can have a level of sulphur less
than or equal to 0.32% measured according to the standard ASTM D5185, preferably less
than or equal to 0.3%, more preferably less than or equal to 0.2%.
In a variant of the invention, the lubricant composition can have a kinematic viscosity at
5 100°C measured according to the standard ASTM D445 comprised between 3.8 and 41 cSt.
In a variant of the invention, the lubricant composition can be free from mo1ybde:numbased
friction modifying additive such as Mo-DTC.
In a variant of the invention, the lubricant composition is an anhydrous composition.
In a variant of the invention, the lubricant composition is in the form of a homogeneous
10 solution.
Another subject of the present invention relates to the use of a lubricant composition as
defined above for reducing the he1 consumption of light vehicles, heavy goods vehic.les or
ships.
'Another subject of the invention relates to an engine oil comprising at lesit one
15 lubricant composition as defined above.
In a variant of the invention, the engine oil can be of grade 5W-30 according to the SAE
5300 classification.
In a variant of the invention, the engine oil can have a viscosity index greater than or
equal to 130, preferably greater than or equal to 150, preferably greater than or equal to 160.
20 Another subject of the present invention relates to a hydraulic oil, a transmissior~o il, a
gear oil, a power steering fluid, a shock absorber fluid, a brake fluid comprising at leilst one
lubricant composition as defined above. Preferably, the transmission oil is a gearbox oil.
Another subject of the present invention relates to the use of at least two glycerol esters
EI and Et, in a base oil, said ester El being an ester of glycerol and of a C12 to CZa carl~oxylic
25 acid, said estcr E2 being an ester of glycerol and of a Cq to CIO carboxylic acid for reducing
the fuel consumption of light vehicles, heavy goods vehicles or ships.
Another subject of the present invention is a process for the lubrication of at least one
mechanical part of an engine, said process comprising a step in which said mechanical part is
brought into contact with at least one lubricant composition as defined above.
3 0 Another subject of the invention is a process for reducing the fuel consumption of a
vehicle, said process comprising a step of bringing a lubricant composition as defined above
into contact with at least one mechanical part of the engine of said vehicle.
In an embodinlent, the vehicle is a light vehicle, a heavy goods vehicle or a ship.
Detailed description
Glycerol. esters .
C Surprisingly, the applicant has demonstrated that the use of at least two chemically
LCI
different glycerol esters, one of the esters being obtained from a "long chain" carb&:d
5 and the other being obtained from a "short chain" carboxylic acid, makes it possit~le to
---r-------
formulate lubricant compositions in particular for engines having very good Fuel. Eco
performance.
The esters used are esters. The first ester El is an ester of glycerol and of a C I ~
to CZ6 carboxylic acid, and the second ester E2 is an ester of glycerol and of a C4 lo CI0
10 carboxylic acid.
The first ester El is an ester of glycerol and of a Cl2 to C26, preferably Clq to (224: more
preferably C16 to C22, even more preferably Cia to Czo.carboxylic acid.
Preferably, glycerol ester El is an ester of glycerol and of a'Cl2 to C26 carboxylic: acid,
the hydrocarbon chain of the carboxylic acid comprising at least two unsaturations.
The first ester El is an ester of glycerol and of a CIZ to C26, preferably C Ito~ C 24. more
preferably C16 to C22, even more preferably Cla to Czo fatty acid.
By "fatty acid" is meant, within the meaning of the present invention, a carboxy1:ic acid
comprising from 12 to 16 carbon atoms, preferably fiom 14 to 24 carbon atoms, more
preferably from 16 to'22 carbon atoms, even more preferably from 18 to 20 carbon'atonls. .
The fatty acids used for preparing glycerol ester El are saturated or unsaturated, linear
or branched, fatty acids optionally substituted with hydroxyl andlor epoxide groups.
Advantageously, glycerol ester El is obtaincd fiom raw materials of renewable oI-.gin.
By '"raw materials of renewable origin" is meant, within the meaning of the present
invention, raw materials that contain carbon 14, denoted 14c, in contrast to the raw materials
derived' from fossil material. Measurements carried out by the methods described in the
international standard ASTM D6866-06, in particular by mass spcctrometry or by liquid
scintillation spectrometry, thus'make it possible to distinguish raw materials originating from
renewable material from raw materials of fossil origin. These measurements can be used as a
test for identifying the origin of raw materials.
The fatty acids that can be used for forming the first glycerol ester El are for example
the following fatty acids used alone or in a mixture: lauric acid, myristic acid, pcntadecyl
acid, palmitic acid, margaric acid, stearic acid,' arachidic acid, behenic acid, lignoceric acid,
cerotic acid, isopalmitic acid, isomargaric acid, ante-isomargaric acid, isostearic acitl, anteisostearic
acid, hypogaeic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid,
petroselinic acid, gadoleic acid, gondoic acid, ketoleic acid, erucic acid, brassidic acid,
nervonic acid, linoleic acid, hiragonic acid, linolenic acid, y-linolenic acid, eleostearic acid,
parinaric acid, homo-y-linolenic acid, arachidonic acid, clupanodonic acid, tariric acid,
santalbic acid or xymenic acid, isanic acid, dihydroxystearic acid, phellonic acid, ceret~ronic
5 ' acid, ricinoleic acid, lesquerolic acid, hydroxynervonic acid, densipolic acid, kamlonenic acid, I
licanic acid, vernolic acid, coronaric acid.
These various fatty acids can be found in the fdlowing vegetable oils, fats of animal or
vegetable origin, and waxes: beeswax, almond oil, peanut oil, babassu oil, spem~acetib, aobab
oil, butterfat, tung oil, cocoa butter, camelina oil, carnauba wax, samower oil,'chaulmoogra .
10 oil, horse fat, colza oil, copra oil, cottonseed oil, croton oil, herring oil, illipe butter, jojoba
oil, shea butter, lanolin, lignite wax, linseed oil, maize germ oil, menhaden oil, cod liver oil,
mustard oil, hazelnut oil, walnut oil, new colza oil, kernel oil, carnation oil, goose fat, oiticica
oil, olive oil, evening primrose oil, bone fat, palm oil, cabbage palm oil, grapesee:d oil,
neatsfoot oil, shark liver oil, castor oil, rice bran oil, lard, sardine oil, sesame oil, soya oil,
spermaceti, tallow, sunflower oil, tall oil etc.
The preferred oils are palm oil, olive oil, peanut oil, colza oil, sunflower oil, soya oil,
maize oil, safflower oil, carnelina oil, flax oil or cottonseed oil. More preferably the oils are
! peanut oil, colza oil, sunflower oil, soya oil, maize oil, safflower oil, camelina oil, flax oil or
.j
cottonseed oil. Even more preferably the oils are sunflower oil, soya oil, maize oil, safflower
oil or cottonseed oil. The preferred oils comprise a non-negligible quantity of linolei~: acid, ,
i.e. they comprise from 25 to 85% by mass of lboleic acid relative to the.tota1 mass c~ff atty
acids of the oils, preferably fiom 35 to'75%, preferably from 45 to 65%:
The glycerol cstcrs El according to the invention are advantageously mixhlres of
glycerol monoesters, glycerol diesters, glycerol triesters and free glycerol. 3. . : .
Preferably, the glycerol esters El according to the invention comprise from 0.1 to 15%
by mass of free glycerol, relative to the total mass of the glycerol esters, more preferably from
0.5 to 1 O%, even more preferably from 1 to 5%.
Preferably, the glycerol esters El according to the invention comprise from 30 1:o 70%
by mass of glycerol monoester, relative to the total mass of the glycerol esters, more
preferably from 40 t0,6O%, even more preferably fiom 45 to 55%.
Preferably, the glycerol esters El according to the invention comprise from 20 ::o 60%
by mass of glycerol diester, relative to the total m'ass of the glycerol esters, more preferably . .
fiom 30 to 50%, even more preferably fiom 35 to 45%.
Preferably, the glycerol esters El according to the invention comprise from 1 to 20% by i
mass of glycerol triester, relative to the total mass of the glycerol esters, more prefcrably from
2 to 15%, even more preferably from 5 to 10%.
The glycerol esters El are- obtained by esterification of glycerol and fatty acids or by
5 transesterification. These chemical reactions, well known to a person skilled in the art, can
take place with or without catalyst, with or without solvent.
The other glycerol ester denoted E2 is an ester of glycerol and a Cq to Clo, preferably Cs
to Cs, more preferably Cg to Cg, more preferably C7 carboxylic acid.
By "short chain or short-chain" &boxylic acid is meant, within the meaning of the
present invention, a carboxylic acid comprising fiom 4 to 10 carbon atoms, preferably f:om 5
to 9 carbon atoms, preferably from 6 to 8 carbon atoms, preferably with 7 carbon atoms.
The carboxylic acids used for preparing glycerol ester E2 are saturated or unsaturated,
linear or branched carboxylic acids, optionally substituted with hydroxyl andjor ernoxide
groups.
In an embodiment, glycerol ester E2 is obtained fiom raw materials of rkneivable origin.
The carboxylic acids that can be used for forming the second glycerol ester E2 Ere for
example carboxylic acids originating from vegetable. oils, fats of animal or vegetable origin
such as butyric acid, valeric acid, caproic acid, heptylic acid, caprylic acid; pelargonic acid,
capric acid, crotonic acid, isocrotonic acid, sorbic acid, isovaleric acid, used alone or in a
mixture.
In another embodiment, glycerol ester E2 is obtained fiom raw materials of fossil origin.
The term synthetic carboxylic acids is then used.
It is also possible to use synthetic carboxylic acids such as butanoic acid, pentanoic
acid, hexanoic acid, heptanoic acid, oct'anoic acid, nonanoic acid, decanoic acid, used alone or
in a mixture.
The glycerol esters E2 according to the invention are advantageously mixtures of
glycerol monoesters, glycerol diesters, glycerol triesters and free glycerol.
Preferably, the glycerol esters E2 according to the invention comprise from 0.1 to 20%
by mass of free glycerol, relative to the total mass of the glycerol esters, more preferably fiom
30 0.5 to 15%, even-more preferably from 1 to 10%.
Preferably, the glycerol esters E2 according to the invention comprise fiom 30 to 70%
by mass of glycerol monoester, relative to the total mass of the glycerol esters, more
preferably from 40 to 60%, even more preferably from 45 to 55%.
Preferably, the glycerol esters E2 according to the invention comprise from 20 to 60%
by mass of glycerol diester, relative to the total mass of the glycerol esters, more prefc:rably
from 30 to 50%, even more preferably from 35 to 45%.
Preferably, the glycerol esters Ez according to the invention comprise from 1 to 15% by
mass of glycerol triester, relative to the total mass of the glycerol esters, more'preferably from
2 to lo%, even more preferably from 5 to 8%.
The glycerol esters E2 are obtained by reacting C4 to Clo carboxylic acids with glj'cerol.
These chemical reactions, well known to a person skilled in the art, can take place with or
without catalyst, with or without solvent.
In the composition according to the invention, the sum of the mass of ester El
and the mass of glycerol ester E2, in their monoester, diester and triester forms, as vrell as
glycerol optionally present, represents from 0.1 to 5% by mass, relative to the total m.ass of
the lubricant composition, preferably from 0.2 to 4%, more preferably fiom 0.5 to 3%., even
more preferably from 1 to 2%.
The mass ratio of glycerol ester El to glycerol ester E2, in their monoester, diestcr, and
triester forms as well as glycerol optionally present, is between 10: 1 and 1 : 10, prejerably
between 5: 1 and 1 :5, more preferably between 2: 1 and 1 :2, even more preferably is equal to
1-1.
Level of ash
Preferably, the lubricant composition according to the invention is a so-called low-ash
composition (LOW SAPS).
By the term "low ash" (LOW SAPS) is meant lubricants specifically formulated lo meet
certain specifications. These specifications, prepared by the European Automobile
Manufacttkers Association (ACEA), require lubricant compositions to meet limits for content
of sulphated ash (generated by the presence of metals), of sulphur and of phosphorus: hence
the designation "Low.SAPS" for "Sulphated Ash, Phosphorus, sulphur". In the remainder of
the present application, the terms "ash" or "sulphated ash" will be used interchangeably.
In fact sulphur, phosphorus and sulphated ash can damage the post-treatment systems
installed on vehicles. The ash is harmll to the particle filters and phosphorus acts as a poison
of the catalytic systems.
Preferably, the lubricant composition according to the invention has a level of sulphated
ash less than or equal to 0.8% by mass nieasured according to the international standard
ASTM D874, more preferably less than or equal to 0.5% by mass. Preferably, the l~~bricant
composition according to the invention has a level of phosphorus less than or equal to 900
I P Q DE.LH1 27-01-2215' 11 4 32
ppm measured according to the international standard ASTM D5185, more preferably less
than or equal to 500 ppm (ppm means parts per million by mass).
Preferably, the lubricant composition according to the invention has a level of sulphur
below 0.32% measured according to the international standard ASTM D5185, more
5 preferably less than or equal to 0.3%, even more preferably less than or equal to 0.2%.
Base oils
The lubricant compositions according to the present invention comprise one or more
base oils, generally representing at least 50% by mass of the lubricant compositions, generally
more than 70% and being able to be up to 90% or more, relative to the total mass .af the
10 lubricant compositions.
The base oil or oils used in the lubricant compositions according to the present
. invention can be oils of mineral or synthetic origin of groups I to V according to the classes
defined in the API classification (American Petroleum Institute (or their equhalents
according to the ATIEL classification (Association Technique de 1'Industrie EuropCemle des
15 Lubrifiants - Technical Association of the European Lubricants Industry)) as summarized
below, alone or in a mixture.
Saturates content Sulphur content Viscosity index (~1)-
-
Group I Mineral oils < 90% > 0.03% 80 sVI < 120
-
Group 11 Hydrocracked 2 90% 10.03% 80 l; VI < 120
oils
-
Group 111 r 90% 10.03% 2 120
Hydrocracked or hydroisomerized
oils
-
Group IV (PAO) Polyalphaolefins
I Group V I Esters and other bases not included in bases of groups I to 111 I I I -J
These oils can be oils of vegetable, animal, or mineral origin. The mineral base oils
according to the invention include all types of bases obtained by atmospheric and vacuum
distillation of crude oil, followed by refining operations such as solvent extraction,
20 deasphalting,. solvent dewaxing, hydrotreatment, hydrocracking and hydroisomerization,
hydrofinishing.
The base oils of the'lubricant compositions according to the present invention can also
be synthetic oils, such as certain esters of carboxylic acids arid alcohols, or polyalphaolefins.
The polyalphaolefins used as base oils, and which are different from. the heavy
10 i
1
polyalphaolehs also present in the cbmpositions kcording to the present invention, are for
example obtained from monomers having fiom 4 to 32 carbon atoms (for example 'octene, j i
decene), and a viscosity at 100°C between 1.5 and 15 cSf measured according to the
I
international standard ASTM D445. Their mass-average molecular mass is typically between I
I
'5 250 and 3000 glmol measured according to the international standard ASTM D5296. I
1
Mixtures of synthetic and mineral oils can also be used.
J
Preferably, the compositions according to the present invention have a kinematic 1
viscosity at 100°C (KV100) between 3.8 and 41 cSt measured according to the international 1
. : standard ASTM D445, preferably between 3.8 and 32.5 cSt, even more preferably between
I
10 3.8 and 24 cSt:
Preferably, it will advantageously be possible to use base oils having a sulphur content 1
below 0.3% for example mineral oils of group 111, and synthetic bases free from sulphur, i .
E
preferably of group IV, or a mixture thereof 1
Thus, the lubricant composition according to the present invention can contain at least
15 70% of base oil, typically at'least 60% by mass of one or more group III base oils and at least i f
10% by mass of one or more group IV base oils, relative to the total mass of.the lubricant 1
composition. t
In a preferred embodiment, the composition according to the invention is an engine oil i
j
having a kinematic viscosity at 100°C (KVlOO), measured according to the international
20 standard ASTM D445, between 3.8 cSt and 26.1 cSt, preferably between 4.1 cSt and 21.9 cSt,
preferably between 5.6 cSt and 16.3 cSt. The engine oils according to the invention are of
grade 20, 30 and 40 according to the SAE 5300 classification, preferably of grade 30 or of
grade 40. According to an especially preferred embodiment, the compositions according to
the present invention are of grade 5W-30 according to the SAE 5300 classification (SAE
25 stands for Society of Automotive Engineers).
The engine oils according to the present invention preferably have a viscosity index VI
greater than or equal to 130, preferably greater than or equal to 150, preferably greater than or
equal to 160.
In another embodiment, the lubricant composition according to the invention is' a
30 transmission oil, preferably a gearbox oil, having a kinematic viscosity' at 100°C measured
according to the standard ASTM D445, between 4.1 cSt and 41 cSt, preferably between 4.1
cSt and 32.5 cSt, preferably between 4.1 cSt and 24 cSt, preferably 'between 4.1 cSt and 18.5
cSt. The transmission oils according to the invention are of grade 75W, 80W, 85W, 80, 85
and 90 according to the SAE 5306 classification.
Other additives
The composition according to the invention can further comprise at least one additive or
several additives as described below. The additive or additives that 'are added are selected
depending on the use of the lubricant composition. These additives can be introduced
separately andlor included in additive packages used in the formulationi of lubricant
compositions in particular for engines.
Thus, the lubricant compositions according to the invention can in particular and
non-limitatively contain anti-wear and extreme pressure additivcs, antioxidants, detetgents
that are overbased or not, polymers improving the viscosity index, pour point improvers,
dispersants, anti-foaming agents, thickeners etc.
The anti-wear and extreme pressure additives protect friction surfaces by the formation
of a protective film adsorbed on these surfaces.
There is a great variety of anti-wear additives,'but the category most used in lubricant
compositions in particular for engines is that of the phosphorus- and sulphur-containing
additives such as the metal alkylthiophosphates, in p&cular the zinc alkylthiophosphates,
and more specifically the zinc dialkyldithibphosphates or ZnDTP. The preferred compounds
are of formula Z~((SP(S)(ORI)(OR~)w)~he, re Rl and R2 are alkyl groups, preferably
comprising from 1 to 18 carbon atoms.
The amine phosphates are also commonly used anti-wear additives. However, the
phosphorus supplied by these additives acts as a poison of automotive catalytic systems, and
they also supply ash. These effects can be minimized by partially substituting with additives
that do not supply phosphorus, such as for example the polysulphides, in particular the
sulphurcontaining olefins.
Anti-wear and extreme pressure additives of the nitrogen-containing and sulphurcontaining
type, for example the metal dithiocarbamates, in particular molybdenum
dithiocarbamate, which also generate ash, are also usually found in the lubricant
compositions.
The anti-wear and extreme-pressure additives are present in the lubricant compositions
according to the invention in contents between 0.01 and 6% by mass, preferably between 0.05
and 4%, more preferably between 0.1 and 2%, relative to the mass of the lubricant
compositions. .
Friction modifiers can optionally be added to the lubricant compositions comprising at
least two glycerol esters El and E2.
These fiiction modifiers optionally added to the lubricant compositions in particular for
four-stroke engines can be compounds supplying metal elements or ash-free compounds.
There can also be solid compounds such as molybdenum disulphide, graphite or
polytetrafluoroethylene (PTF.E).
5 The metal compounds are for example complexes of transition metals such as Mo, Sb,
Sn, Fe, Cu, Zn, the ligands of which can be hydrocarbon compounds containing oxygen,
nitrogen, sulphur or phosphorus atoms. In particular, the compounds containing molybdenum
can be particularly effective, such as for example the molybdenum dithiocarbamal.es or
dithiophosphates.
10 The ash-free 'friction modifiers can be for example fatty alcohols, fatty acids, esters,
fatty mines.
These friction modifying additives, optionally added, are present in contents between
0.01 and 5% by mass relative to the total mass of the lubricant composition, preferably. 0.1
and 2%. By combining two glyckrol esters El and Ez, it is possible to formulate lubricant
15 compositions which have, advantageously during the phase of engine starting, improved
tiiction properties relative to the lubricant compositions comprising Mo-DTC. These fiiction
modifiers El and E2 have the advantage of being additivs that do not supply sulphated ash,
phosphorus and sulphur.
In an embodiment, the lubricant composition according to the invention can in addition
20 to the glycerol esters El and E2 further comprise other friction modifiers, but the quantity
thereof wilL be limited.
In an embodiment of the invention, the quantity of tXc,tion modifiers other than the two
glycerol esters El and E2 is less than or equal to 2% by mass, relative to the total mass of the
lubricant composition, more preferably less than or equal to 1% by mass, even more
25 preferably less than or equal to 0.5% by mass, even more preferably less than or equal to
0.1 % by mass.
Preferably, the quantity of friction modifiers supplying ash, such as the molybdenumbased
friction modifiers, such as MoDTC, is less than or equal to 2% by mass, relative to the
total mass of the lubricant composition, more preferably less than or equal to 1% by mass,
30 even more preferably less than or equal to 0.5% by mass, even more preferably less than or
equal to 0.1% by mass.
In another embodiment of the invention, the lubricant compositions according to thc
present invention are devoid of fiiction modifiers supplying ash, for example the
molybdenum-based fiiction modifiers, such as MoDTC.
13
i
The antioxidants slow down the degradation of the oils in service; degradation which
I ' can rcsult in the formation of deposits, the presence of sludge, or an increase in the viscosity
of the oil. They act as radical inhibitors or hydroperoxide destroyers. The antioxidants
commonly used include the antioxidants .of the phenolic or amino type. Some of these i
5 additives, for example the phosphorus- and sulphur-containing antioxidants, may generate
ash.
The phenolic antioxidants may be ash-fiee, or be in the .form of neutral or basic metal
salts. Typically, they are compounds containing a sterically hindered hydroxyl group, for
example when two hydroxyl groups are in the ortho or para position relative to one another,
10 or when the phenol is substituted with an alkyl group comprising at least 6 carbon atoms.
The amino compounds are another class of antioxidants that can be used, option;~llyin
combination with the phenolic antioxidants. Typical examples are the aromatic amines, of ?
formula RgRgRloN, where Rg is an aliphatic group, or an optionally substituted aromatic
group, Rs is an optionally substituted aromatic group, Rlo is hydrogen, or an alkyl or aryl
15 group, or a group of formula RI~S(O),R~w~h,e re R11 andlor R11 is an alkylene, alkenylene, or
aralkylene group, 'and x is an integer equal to 0, 1 or 2.
Sulphurized alkyl phenols or their alkali-metal and alkaline-earth salts are also used as
antioxidants.
Another class of antioxidants is that of the oil-soluble copper compounds, for en.ample
20 the copper thio- or dithiophosphates, the salts of copper and carboxylic acids, the copper
dithiocarbamates, sulphonates, phenates, and acetylacetonates. The copper I and I1 salts of
succinic acid or anhydride are used.
The antioxidants, alone or in a mixture, are typically present 'in the lul~hcant
compositions according to the invention in quantities comprised between 0.1 and 5% by mass, j
25 relative to the total mass of the lubricant compositions.
The lubricant compositions according to the present invention can contain all opes of i
antioxidant additives known to a person skilled in the art. The ash-free antioxidants will be
preferred. 8
The deter~erits reduce the formation of deposits on the surface of metal parts by I
30 dissolving the by-products of oxidation ahd combustion. The detergents that can be used in
the lubricant compositions according to the present invention are familiar to a person skilled I
, .
in the art. . :
The detergents commonly used in the formulation of lubricant compositions are
typically anionic compounds comprising a long lipophilic hydrocarbon chain. and a
I P . 0 DELHI 2 7 - 0 1 -
hydrophilic head. The, associated cation is typically a metal cation of an alkali or alkalineearth
metal.
The detergents are preferably selected from the alkali- or alkaline-earth metal sa1ts of
carboxylic acids, sulphonates, salicylates, naphthenates, as well as the salts of phenate.
5 The alkali and alkaline-earth metals are preferably calcium, magnesium, sodium or
barium.
These metal salts can contain the metal in an approximately stoichiometric quantity or
in excess (in a quantity greater than the stoichiometric quantity). In the latter case, these
detergents are referred to as overbased detergents.
10 The excess metal providing the detergent with its overbased character is present in the
form of metal salts which are insoluble in oil, for example carbonate, hydroxide, oxalate,
acetate, glutamate, preferably carbonate.
The viscositv index irnuroving uolvrners make it possible to guarantee good lowtemperature
stability and minimum viscosity at high temperature, in particular for formulating
15 multigrade oils. Addition of these compounds to the lubricant compositions allows th.em to
reach viscosity index (VI) values giving them good Fuel Eco properties or fuel savings.
Thus, preferably, the viscosity index (VI) of the lubricant compositions according to the
invention, measured according to the international standard ASTM D2270, is greater than or
equal to 130, preferably greater than or equal to 1'50, preferably greater than or equal to 160.
20 these compounds, the polymer esters, the copolymer olefins (CPO), the
homopolymers or copolymers of styrene, butadiene or isoprene, hydrogenated or not, and the
polymethacrylates (PAW) may foi example be mentioned.
The lubricant compositions according to the present invention can contain of the order
of 0.1 to 10% by mass of viscosity index improving polymers, relative to the total mass of the
25 lubricant compositions, preferably from 0.5 to 5%, preferably from 1 to 2%.
,The uour uoint de~ressants improve the low-temperature behaviour of the oils, by
slowing the formation of paraffiri crystals. These are for example alkyl polymethacryldes,
polyacrylates, 'polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated
polystyrenes etc.
3 0 The disuersants, such as for example succinimides, PIB (polyisobutene) su'ccinimides,
Mannich bases, ensure maintenance in suspension and the removal of insoluble solid
impurities constituted by the oxidation by-products that form when a lubricant composition is
in service.
The surfaces
The lubricant compositions according to the invention can be used for lubricating the
surfaces of the parts that are conventionally found in an engine such as the system bf pistons,
rings, liners. They can. also be used for lubricating transmission systems such as manu@ or
automatic gearboxes. The lubricant compositions according to the invention can be used in
light vehicles, heavy goods vehicles, but also in ships.
Another subject of the present invention is a process for the lubrication of at least one
mechanical part of an engine, said process comprising a step in which said mechanical part is
brought into contact with at least one lubricant composition as defined above.
In an embodiment, the mechanical part is' selected from the group comprising the
system of pistons, rings, liners.
Ln another embodiment, the mechanical part forms a mechanical component such as
transmission systems, preferably manual gearboxes or automatic gearboxes.
Another subject of the invention' is a process for reducing the he1 consurnptioll of a
vehicle, said process comprising a step of bringing a lubricant composition as defined above
into contact with at least one mechanical part of the engine of said vehicle.
In an embodiment, the vehicle is a light vehicle, a heavy goods vehicle or a ship.
. .
Example P
A control lubricant composition T not comprising fiction modifiers is prepared film: - - a group I11 base oil having a kinematic viscosity at 100°C (KV100) equal to 6 cSt (measured
according to the international standard ASTM D445),
- a group I11 base oil having a kinematic viscosity at 100°C (KVIOO) equal to 4 cSt (measured
according to the international standard ASTM D445),
- a light polyalphaolefin (PAO), group IV base oil having a kinematic viscosity at 100°C
(KV 100) equal to 6 cSt (measured according to the international standard ASTM D445),
- a linear ethylene/propylene olefin copolymer (OCP), comprising 50% by mass of ethylene,
relative to the mass of the copolymer, having a weight average molecular mass Mw equal to
171,700 glmol (measured according to the international standard ASTM D5296) and a
number average molecular mass Mn equal to 91,120 dm01 (measured according to the
international standard ASTM D5296),
- a heavy PA0 having a kinematic viscosity at 100°C (KV100) equal to 1000 cSt (measured
according to the international standard ASTM D445),
- a pour point depressant (PPD) which is a polymethacrylate,
- an additive package comprising slightly and highly overbased detergents, phenolic and
amine antioxidants, a dispersant of the succinimide type, an anti-wear- additive based on
amine phosphate and zinc dialkyl dithiophosphate (ZnDTP),
The percentages by mass of the different constituents are given in Table I below, as well
I 5 as the pmperties of this control lubricant composition.
I (') measured according to the international standard ASTM D5 185
! (2) measured according to the international standard ASTM D5 1 85
i , (3) measured according to the international standard ASTM D874
(4) measured according to the international standard ASTM D2896
10 (') measured according to the international standard ASTM D445
(6) measured according to the international standard ASTM D445
Table I
15
Various fiction modifiers are added to this composition:
Mixture of group I11 base oils,% by mass
Light P A 0 3 by mass
OCP,% by mass
Heavy PAO,% by mass '
PPD,% by mass
Additive package,% by mass
Total,% by mass
Phosphorus, ppm, "'
Sulphur, ppm, '2)
. .
Sulphated ash,% by mass, ('I
TBN (Total Base Number), mg KOWg, (4)
KV100, cSt, (5)
KV40, cSt, '6'
Viscosity index
- Glycerol monooleate (GMO) marketed by Stdeerie Dubois imder the name DUB OG.
Control composition T
65.6
15;2
2.2
3.0
0.2
13.8
100.
501
1346
0.5
5.95
9.94
57.8 1
159
- Glycerol linoleate comprising 45% by mass of monoester, relative to the total mass of
glycerol linoleate, 40% by mass of diesters, 10% by mass of triesters, 5% by mass of free
glycerol. This glycerol linoleate is obtained from a mixture of fatty acids, with the lholeic
acid representing 75 to 80% by mass of the total mass of the fatty acids, the remainder bekg
5 constituted by:
myristic acid (less than 1% of the total mass of the fatty acids),
palmitic acid (5 to 8% of the total mass of the fatty acids),
stearic acid (2 to 3% of the total mass of the fatty acids),
oleic acid (1 1 to 15% of the total mass of the fatty acids),
10' linolenic acid (less than 2% of the total mass of the fatty acids),
a arachidic acid (less than 1 % of the total mass of the fatty acids) and
gadoleic acid (less than 1% of the total mass of the fatty acids).
This ester is marketed by St6arinerie Dubois under the name DUB LIG.
- Glycerol heptanoate, comprising 47% by mass of monoester, relative to the total mass of
15 glycerol heptanoate, 36% by mass of diesters, 6% by mass of triesters, 1 1% by mass of free
glycerol. This ester is obtained fiom heptanoic acid.
- a pentaerythritol ester, as described in the application W0201'0064220 having the following .
characteristics: nl = 73.2%, n2 = 26.8%, KV~OO= 4.657 cSt, KV40 = 18.50 cSt, with
viscosity index = 183.
20 - molybdenum dithiocarbamate marketed under the name Sakura-lube 525 by the colnpany
Adeka.
The composition C7 illustrates a composition comprising Mo-DTC, the level of . .
treatment of which is usually in the lubricant compositions available on the market with 400 !
gpm by mass of Mo-DTC. i
?
25 The percentages by mass of the resultant compositions are given in Table I1 below.
Table I1
The physicochemical characteristics of the resultant compositions are given in Tal~leI1 1
. ' below.
5
Table 111
(I) measured according to the international standard ASTM D5 185
(2) measured according to the international standard ASTM D5 1 85
10 (3) measured according to the international standard ASTM D874
measured according to the international standard ASTM D445
c3
99%
-
-
.1%
c2
99%
- '
1%
-
-
ControlcompositionT
Glykrol monooleate
Glycerol linoleate
Glycerol heptanoate
Pentaerythritol ester
Molybdenum
dithiocarbamate (Mo-
DTC)
(6) measured according to the international standard ASTM D445
CI
99%
1%
-
-
-
KV100, cSt, ('I
KV40, cSt,
Sulphated ash,% by
mass, (3)
Sulphur, PPm, (2)
P ~ O S ~ ~ pOpm~,U (I)S ,
Then the fiction coefficient of the compositions is measured by a Cameron Plint
15 Friction laboratory test using a reciprocating tribometer of the ~arneron- lint TE-77 typz. The
test bench consists of a cylinder-on-flat tribometer h e r s i d in the oil to be tested. A variable
normal force .is applied to the heated flat and the resultant fictional force is measuretl. The
c4
98%
-
1% ,
1%
c2
10.07.
57.53
0.5
1346
501
c I
10.07
'57.59
0.5
. .
1346
501
CS
99%
-
0.5% .
0.5%
c3
10.02
57.76
0.5
1346
501
c6
99%
- '
-
1%
c4
10.05
57.76
0.5
1346
501
c7
99.6%
-
-
-
0.4%
CS
10.04
57.66
0.5
1346
501
c6
10.11
57.29
0.5
1346
50i
c7
10.08
57.54
>0.5
>I346
>501
. .
19
j
conditions of temperature, load and frequency are varied. The values of the kiction 1
coefficient, obtained at different temperatures, loads and frequencies, are shown in Table IV i
as well as the overall mean value of these six different phases.
5 Table IV
c6
0.083
0.095
0.109
0.132
0.128
0.121
0.11 1
c7
0.086
0.058
0.057
0.097
0.098
0.074
0.080
c1
0.145
0.106
0.1 11
0.123
0.120
0.127
0.122
mean friction
coefficient
(55 N, 100°C, 40
Hz)
mean fiiction
coefficient
(155 N, 100°C, 40
mean friction
coefficient
(255 N, 100°C, 40
Hz)
mean friction
coefficient
(255 N, 150°C, 5
Hz)
mean friction
coefficient ,
(255 N, 150°C, 20
Hz)
mean friction
coefficient
(255 N, 150°C, 40
Hz)
overall mean
friction coefficient
c2
0.142
0.104
0.096
0.118
0.105
0.102
0.111
T
0.127
0.125
0.137
0.165
0.160
0.148
0.144
c4
0.062
0.038
0.052
0.097
0.103
0.092
0.074
c3
0.075
0.062.
0.0.70
0.162
0.155
0.146
0.112
CS
0.062
0.049
0.058
0.146
0.143
0.131
0.098
It can be seen that the addition of 1% of GMO makes it possible to reduce the overall
mean fiiction coefficient (for all 6 phases) of the lubricant composition.
The same applies to the addition of 1% of glycerol linoleate or 1% of glycerol i ~ i
heptanoate.
5 At 2% of active ingredient, composition C4 has the lowest fiiction coefficient of the
lubricant compositions T, CI to Ctj.
At 1% by mass of active substance, lubricant composition CS based on the mixture of
I long chainlshort chain glycerol esters has a lower overall fiiction coefficient than lubricant . :
$
compositions T, CI to Cj and Ca based on other compounds also at 1% by mass of active
i
I0 substance.
. .
Compositions Cq and Cs make it possible to obtain a lower fiction coefficient thim the I 1 'I
compositions comprising Mo-DTC (composition C7) during the engine starting phases (i.e. n :!
t
the case of temperatures of 100°C).
15 Example 2
l"h; objective of this example is to show the influence of the presence of unsaturations i 1
in the C I t~o Cz6 carboxylic acid of ester El according to the invention on the fiictioi.1 1' I
properties of the lubricant composition. I I I: 4
For this, compositions C8 and C9 are prepared by adding the following fi-iction I
i
modifiers to the control composition of example 1 :
- glycerol monoisostkarate marketed by Stdarinerie Dubois under the name DU:B ISG
and obtained from a saturated C18 carboxylic acid,
- glycerol monooleate marketed by Stdarinerie Dubois under the name DUB OG and
25 obtained from an unsaturated C18 carboxylic acid comprising one unsaturatio~l. The
glycerol monooleate comprises 32-52% by mass of monoester, relative to tha: total
mass of glycerol monooleate, 30-50% by mass of diesters, 5-20% by mass of triesters,
at most 6% by mass of free glycerol.
- glycerol linoleate obtained from an unsaturated Cl8 carboxylic acid comprisirlg two
3 0 unsaturations, its composition is described in Example 1.
- glycerol heptanoate: its composition is described in Example 1.
The percentages by mass of the resultant compositions are given in Table V below.
Friction laboratory test using an reciprocating tribometer of the Cameron-Plint TE-7;' type i
Table V
i t
under the conditions described in Example 1. The results obtained are presented in Table VI. i
;1 :
.
Table VI
Then the friction coefficient of the compositions is measured, by a Cameron Plint Control composition
T
Glycerol
monoisostearate
Glycerol monooleate
Glycerol linoleate
Glycerol heptanoate
10 The results show that the selection of an unsaturated Ci2 to C26 carboxylic acid
comprising at least two unsaturations in order to form ester El according to the invention
allows an even more significant reduction in the overall mean fiction coefficient, relative to a I 1
saturated C12 to'C26 carboxylic acid or an unsaturated C12 to C26 carboxylic acid comprising a i
1
single tinsaturation.
15.
Cs
99%
0.5%
0.5%
Overall mean fiiction
coefficient
cs
99%
0.5%
0.5%
0.5% 0.5%
:
cs
0.098
cs
0.1 10 0.1 12
" 7'
Claims
!
@ 4 0 - 0 Lubricant composition comprising at least one base oil and at least two glycerol e z r s - El and Ez, glycerol ester ,El being an ester of glycerol and of a C12 to CZ6 carboxylic
acid, glycerol ester. E2 being an ester of glycerol and of a C4 to Clo carboxylic acid, said
ester El is a mixture of glycerol monoesters, glycerol diesters, glycerol triesters . a d free
glycerol and said.ester Ez is a mixture of glycerol monoesters, glycerol diesters, glycerol
triesters and free glycerol.
Lubricant composition according to claim 1, in which the carboxylic acids c)f the
glycerol esters El and E2 are saturated or unsaturated, linear or branched carboxylic
acids,.optionally substituted with hydroxyl andlor epoxide groups.
Lubricant composition according to any one of claims 1 or 2, in which glycerol ester El
is an ester of glycerol and of a C14 t o CZQp, referably C16 to CZZm, ore preferably 1Zls to
C20 carboxylic acid.
Lubricant composition according to any one of claims 1 to 3, in which glycerol ester E2
is an ester of glycerol and of a Cs to C9, preferably C6 to Cs,. more preferably C7
carboxylic acid.
Lubricant composition according to any one of claims 1 to 4, in which glycerol ester El
is selected fiom the glycerol linoleates and mixtures thereof, and glycerol ester E2 is
selected from the glycerol heptanoates and mixtures thereof.
Lubricant composition according to any .one of claims 1 to 5, in which the sum of the
masses of the glycerol esters El and E2 represents 0.1 to 5% by mass, relative to the
total mass of the lubricant composition, preferably from 0.2 to 4%, more prefixably.
fiom 0.5 to 3%, even more preferably fiom 1 to 2%.
Lubricant composition according to any one of claims 1 to 6, in which the mass ratio of
the glycerol ester(s) El and the glycerol ester(s) E2 is between 10: 1 and 1 : 10, prefixably
between 5: 1 and 1 :5, more preferably between 2: 1 and 1 :2, even more preferably is
equal to 1 : 1.
Lubricant composition according to any one of claims 1 to 7 having a level of sulphatcd
ash less than or equal to 0.8% measured according to the standard ASTM :3874,
preferably less than or equal to 0.5%. ,'
Lubricrult composition according to any one of claims 1 to 8 having a level of
phosphorus less than or equal to 900 ppm measured according to the standard A.STM
D5 185, preferably less than or equal to 500 ppm.
Lubricant composition according to any one of claims 1 to 9 having a level of su.lphur
Sess than or equal to 0.32% measured according to the standard ASTM D5185,
preferably less than or equal to 0.3%, more preferably less than or eciual to 0.2%.
Lubricant composition according to any one of claims 1 to 10 having a kinematic
,viscosity at 100°C measured according to the standard ASTM D445 between 3.8 and 41
cst.
Lubricant composition'according to any one of claims 1 to 11 fiee fiom mo1ybde:nurnbased
fiiction modifying additive such as Mo-DTC.
Use of a lubricant composition as defined in any one of claims
the &el consumption of light vehicles, heavy goods vehicles or ships.
Engine oil comprising at least one lubricant composition as defined in any one of c:laims
1 to 12. .
Engine oil according to claim 13 that is of grade 5W-30 according to' the SAE 5300
classification.
Engine oil according to claim 14 or 15 having a viscosity index greater than or equal to
130, preferably greater than or equal to 150, preferably greater than or equal to 160.
Hydraulic oil, transmission oil, gear oil, power steering fluid, shock absorbcr fluid,
brake fluid comprising at ledst one lubricant composition as defined in any one of
claims 1 to 12.
Use of at least two glycerol esters El and E2, in a base oil, said ester El being an ester of
glyccrol and of a CI2 to C2,j carboxylic acid, said ester E2'being an ester of glycerol and
of a C4 to Clo carboxylic acid in order to reduce the fuel consumption of light vehicles,
heavy goods vehicles or ships, said ester El is a mixture of glycerol morioc:sters,
glycerol diesters, glycerol triesters and free glycerol and said ester E2 is a mixture of
glycerol monoesters, glycerol diesters, glycerol triesters and free glycerol.