ENGINE LUBRICANT COMPOSITION
Technical field
The present invention relates to lubricant compositions for engines, in particular for
5 engines of gasoline vehicles or diesel vehicles, the use of which makes it possible to
simultaneously obtain satisfactory engine cleanliness and a reduction in the fuel
consumption of said vehicles.
Technological background
Energy efficiency and reducing the fuel consumption of motor vehicle engines is a
10 growing concern. It is known that lubricants for engines used in said vehicles play an
important role in this regard.
In order to formulate "Fuel Eco" lubricants or fuel economy lubricants, it is known
to act on the viscosity of the lubricant bases used. It is also known to use viscosity index (VI)
improver polymers, or to use friction modifiers (FM). However, the viscosity index improver
15 polymers have the drawback of reducing the engine cleaning power of the lubricant
compositions in which they are used. Existing engines have high thermal stresses which
result in significant deposit phenomena. The deposits are linked to the chemical conversion
of the lubricant in the parts that are closest to the combustion chamber and therefore the
hottest.
20 A need therefore exists to have lubricant compositions comprising at least one
viscosity index improver polymer which provide good engine cleanliness and which make it
possible to limit the fuel consumption of gasoline vehicles or diesel vehicles.
An objective of the present invention is the use of new additive compounds; in a
lubricant composition making it possible to formulate a lubricant composition having good
25 properties in terms of engine cleanliness. This objective is achieved by means of the use of
at least one polyalkylene glycol, obtained by polymerization or copolymerization of alkylene
oxides comprising from 3 to 8 carbon atoms, including at least one butylene oxide in a
lubricant composition. Surprisingly, the Applicant company has found that the use of these
polyalkylene glycols as additives advantageously makes it possible to obtain a lubricant
30 composition having good properties as regards engine cleanliness.
Another objective of the present invention is the formulation of a lubricant
composition simultaneously having good engine cleanliness properties and good "Fuel Eco"
properties.
This objective is achieved by means of a lubricant composition for engines, in
35 particular gasoline engines or diesel engines, comprising a specific combination of a
polyalkylene glycol obtained by polymerization or copolymerization of alkylene oxides,
including at least one butylene oxide and at least one viscosity index improver polymer.
Such propylene oxide and butylene oxide copolymers are known from the
document WO2011/011656. These propylene oxide and butylene oxide copolymers have
5 the property of being soluble in the base oils of Groups I to IV used in the formulation of
the lubricants.
The document US 6,458,750 describes an engine oil composition with reduced
deposit-formation tendency, said composition comprising at least one base oil and at least
one alkyl alkoxyalte of formula (I):
10
Ri -f-(CR2R3)n]z L "A R4
(I)
wherein
15 R1/R2/ R3 represents independently one hydrogen atom or a hydrocarbon group
containing up to 40 carbon atoms,
R4 is a hydrogen atom or a methyl group or an ethyl group,
Lis a linker group,
n is an integer ranging from 4 to 40,
20 A is an alkoxy group with 2 to 25 repeating units, which are derived from ethylene
oxide, propylene oxide and/or butylene oxide and comprising homopolymers as well as
statistical copolymers of at least two of the said compounds, and
z is 1 or 2.
However, this document does not disclose a lubricant composition comprising at
25 least one polyalkylene glycol which is a copolymer of butylene oxide and propylene oxide in
which the butylene oxide to propylene oxide mass ratio is selected from the range of values
of the present invention. In addition, this document does not describe the use of a specific
polyalkylene glycol for improving the engine cleanliness, without increasing the
consumption of gasoline or diesel fuel.
30 The document EP0438709 discloses an engine oil comprising at least one base oil,
at least one polymeric viscosity index improver and at least one product resulting from the
reaction of phenols or bisphenol A with at least one butylene oxide or a
butylene/propylene oxide for improving piston cleanliness of automobile engines.
However, this document does not disclose the lubricating compositions according to the
invention. Nor does it disclose the use of polyalkylene glycol as defined by the invent on in
a lubricant composition in order to improve engine cleanliness and reduce fuel
consumption.
5 In order to simultaneously obtain good "Fuel Eco" and cleaning properties, the
quantity of polyalkylene glycol in the lubricant composition must be limited to between 1
and 30% by mass with respect to the total mass of the lubricant composition, the 30%
upper limit being excluded.
10 Summary of the invention
The invention relates to a lubricant composition for engines comprising at least one
base oil, at least one viscosity index improver polymer and at least one polyalkylene glycol,
obtained by polymerization or copoiymerization of aikyiene oxides comprising from 3: to 8
15 carbon atoms, including at least one butylene oxide, the quantity of polyalkylene glycol
being from 1 to 28% by mass with respect to the total mass of lubricant composition.
Preferably, the polyalkylene glycol is a copolymer of butylene oxide and prop/lene
oxide.
Preferably, the butylene oxide to propylene oxide mass ratio is a value of 3:1 to 1:3,
20 preferably a value of 3:1 to 1:1.
Preferably, the polyalkylene glycol has a molar mass measured according to the
standard ASTM D4274 ranging from 300 to 1000 grams per mole, preferably from 500 to
750 grams per mole.
Preferably, the polyalkylene glycol has a kinematic viscosity at 100°C measured
25 according to the standard ASTM 0445 ranging from 1 to 12 cSt, preferably from 3 to 7 cSt,
more preferably from 3.5 to 6.5 cSt.
Preferably, the lubricant composition comprises from 2 to 20% by mass of
polyalkylene glycol with respect to the total mass of the lubricant composition, preferably
from 3 to 15%, more preferably from 5 to 12%, even more preferably from 6 to 10%.
30 Preferably, the viscosity index improver polymer is chosen from the group
consisting of the olefin copolymers, the ethylene/alpha-olefin copolymers, styrene/olefin
copolymers, the polyacrylates alone or in a mixture.
10
Preferably, the lubricant composition comprises from 1 to 15% by mass of viscosity
index improver polymer with respect to the total mass of the lubricant composition,
preferably from 2 to 10%, more preferably from 3 to 8%.
Preferably, the lubricant composition also includes at least one additive chosen
5 from anti-wear additives, detergents, dispersants, anti-oxidants, friction modifiers alone or
in a mixture.
In one embodiment, the lubricant composition consists of:
• from 40 to 80% by mass of base oil,
• from 1 to 28% by mass of polyalkylene glycol, obtained by polymerization
or copolymerization of alkylene oxides comprising from 3 to 8 Ccirbon
atoms, including at least one butylene oxide,
• from 1 to 15% by mass of viscosity index improver polymer,
• from 1 to 15% by mass of additives chosen from the anti-wear additives,
detergents, dispersants, anti-oxidants, friction modifiers alone or in a
15 mixture, the sum of the constituents being equal to 100% anc the
percentage being expressed with respect to the total mass of lubricant
composition.
The invention also concerns the use of a lubricant composition as defined above for
the lubrication of a light or heavy vehicle engine, preferably of light gasoline or cliesel
20 vehicles.
The invention also concerns the use of at least one polyalkylene glycol, obtained by
polymerization or copolymerization of alkylene oxides comprising from 3 to 8 carbon
atoms, including at least one butylene oxide in a lubricating composition in order to
improve engine cleanliness, without increasing the consumption of gasoline or diesel fuel,
25 preferably in order to improve engine cleanliness by reducing the consumption of gasoline
or diesel fuel.
Preferably, this use is aimed at improving engine cleanliness, in particular the
cleanliness of the pistons.
Another subject of the invention is a method for lubricating at least one mechanical
30 part of an engine, said method comprising at least one step in which said mechanical part is
brought into contact with at least one lubricant composition as defined above.
By improving engine cleanliness is meant within the meaning of the present
invention reduction in formation of deposits, notably the formation of deposits at high
temperatures such as glazes, lacquers or carbon deposits, coke deposits which form on the
5
10
hot surfaces of engine parts such as the bottoms of piston ring grooves or turbocharger
shaft. Molecules of lubricant compositions can become oxidized upon contact with hot
surfaces of the engine and lead to the formation of insoluble products, forming deposits.
These deposits will clog up the engine and lead to problems of wear, seizure, gumming of
piston rings, and problems with turbocharger rotation, for example. Generally, detergenttype
additives are employed for improving engine cleanliness. The Applicant connpany
proposes using another type of additives for improving engine cleanliness. The lubricating
composition according to the invention makes it possible to resolve problems of engine
cleanliness, notably the above formation of deposits.
Detailed description
15
20
Polvalkylene glycol bases
The polyalkylene glycols used in the compositions according to the invention have
properties suitable for use in an engine oil. These are (random or block) alkylene oxide
polymers or copolymers which can be prepared according to the known methods described
in the application WO 2009/134716, page 2 line 26 to page 4 line 12, for example by attack
by an alcohol initiator on the epoxy bond of an alkylene oxide and propagation of the
reaction.
The polyalkylene glycols (PAGs) of the compositions according to the invention
correspond to general formula (A):
25
Y 1 O
H
C
R 2x-1
H c
R 2x
n
o Y
30
wherein
(A)
Yi and Y2 are, independently of each other, hydrogen, or a hydrocarbon group, for
example an alkyl or alkylphenyl group, having 1 to 30 carbon atoms,
- n represents an integer greater than or equal to 2, preferably less than 60,
preferably ranging from 5 to 30, preferably ranging from 7 to 15,
- x represents one or more integers ranging from 1 to n,
- the R2x-i and R2x groups are, independently of each other, hydrogen, or hydrocarbon
5 radicals, comprising from 1 to 6 carbon atoms, preferably alkyl groups.
R2x_iand R2xare preferably linear.
Preferably at least one of R2x_iand R2x is hydrogen.
R2x is preferentially hydrogen.
The sum of the numbers of carbon atoms of R2x_i and R2x is of a value ranging from 1 to 6.
10 For at least one value of x, the sum of the numbers of carbon atoms in R2x_! and R2x is equal
to 2. The corresponding alkylene oxide monomer is butylene oxide.
The alkylene oxides used for the PAGs of the compositions according to the
invention comprise from 3 to 8 carbon atoms. At least one of the alkylene oxides entering
into the structure of these PAGs is a butylene oxide, said butylene oxide being 1,2-butylene
15 oxide or 2,3-butylene oxide, preferably 1,2-butylene oxide.
In fact, the PAGs obtained, in part or in whole, from ethylene oxide do not have a
sufficiently lipophilic nature to be used in engine oil formulae. In particular, they canrot be
used in combination with other mineral, synthetic or natural base oils .
Neither is the use of alkylene oxides comprising more than 8 carbon atoms desired
20 as, in order to produce bases having the molar mass and therefore the targeted
viscosimetric grade for engine applications, there will then be a reduced number of
monomers (low n in formula (A) above), with long R2x_i and R2x side chains. This is
detrimental to the overall linear nature of the PAG molecule and leads to viscosity indices
(VI) too low for an engine oil application.
25 Advantageously, the polyalkylene glycol may be a copolymer of butylene oxide and
propylene oxide with the butylene oxide to propylene oxide mass ratio being a value of 3:1
to 1: 3, preferably between 3: 1 to 1: 1, the polyalkylene glycol having the general fo mula
30
(A):
H H i
Y1 | O C C O Y
f^2x-1 ^2x
wherein
- Yx and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 to
30 carbon atoms,
5 - n represents an integer greater than or equal to 2, preferably less than 60,
preferably ranging from 5 to 30, preferably ranging from 7 to 15,
- x represents one or more integers ranging from 1 to n,
- the R2x-i and R2x groups are, independently of each other, hydrogen, or hydrocarbon
radicals, comprising from 1 to 2 carbon atoms,
10 - for at least one value of x, the sum of the numbers of carbon atoms in R2x-iand R2x
is equal to 2.
Preferably, the viscosity index VI (measured according to the standard NFT 60136)
of the PAGs according to the invention is greater than or equal to 100, preferably greater
than or equal to 120.
15 In order to confer a sufficiently lipophilic nature upon them, and therefore a good
solubility in synthetic base oils, mineral or natural base oils, and good compatibility with
certain additives essential to the engine oils, the PAGs according to the invention are
obtained from alkylene oxides comprising at least one butylene oxide.
Among these PAGs, the butylene oxide (BO) and propylene oxide (PO) copolymers
20 are particularly preferred, as they have both the good tribological and rheological
properties of PAGs containing ethylene oxide units and/or polypropylene, and a good
solubility in standard mineral, synthetic, and natural bases, and other oily compounds.
The application WO2011/011656, paragraphs [011] to [014] describes the method
of preparation, characteristics, and properties (in particular solubility and miscibility in base
25 oils) of such butylene oxide and propylene oxide copolymer PAGs.
These PAGs are prepared by reaction of one or more alcohols with a mixture of
butylene oxide and propylene oxide.
In order to confer upon the PAGs a good solubility and good miscibility in mineral,
synthetic and natural base oils, it is preferred to use, in the compositions according to the
30 invention, PAGs prepared with a mixture of butylene oxide and propylene oxide where the
mass ratio of butylene oxide to propylene oxide is a value of 3:1 to 1:3. The PAGs prepared
with a mixture where this ratio is a value of 3:1 to 1:1 are particularly miscible and soluble
in base oils, including synthetic oils of Group IV (polyalphaolefins).
According to a preferred embodiment, the PAGs of the compositions according to
the invention are prepared from alcohol comprising from 8 to 12 carbon atoms. 2-
ethylhexanol and dodecanol, alone or in a mixture, and in particular dodecano, are
particularly preferred, as the PAGs prepared from these alcohols have very low traction
5 coefficients.
According to a preferred embodiment, the PAGs according to the invention are
such that their carbon to oxygen molar ratio is greater than 3:1, preferably ranging from 3:1
to 6:1. This confers upon said PAGs polarity and viscosity index properties particularly
suitable for use in engine oil.
10 The molar mass, measured according to the standard ASTM D2502, of the PAGs
according to the invention has preferably a value ranging from 300 to 1000 grams per mole
(g/mol), preferably ranging from 350 to 600 g/moi (this is why they contain a limited
number of alkylene oxide units n as described above in formula (A)).
The molar mass of the PAGs according to the invention measured according 1o the
15 standard ASTM D4274 preferably has a value ranging from 300 to 1000 grams per mole
(g/mol), preferably from 500 to 750 grams per mole.
This confers upon them kinematic viscosities at 100°C (KV100) ranging generally
from 1 to 12 cSt at 100°C, preferably from 3 to 7 cSt, preferably from 3.5 to 6.5 cSt, or from
4 to 6 cSt or from 3.5 to 4.5 cSt. The KV100 of the compositions is measured accord ng to
20 the standard ASTM D445.
The use of light PAGs (KV100 approximately from 2 to 6.5 cSt) are preferably
chosen in order to be able to more easily formulate multigrade oils of low temperature
grade 5W or OW according to the SAEJ300 classification, as the heavier PAGs have lowtemperature
properties (high CCS) which do not make it possible to easily achieve these
25 grades.
Lubricant composition
Another subject of the invention is a lubricant composition for engines, in particular
for gasoline engines or for diesel engines, comprising at least one base oil, at least one
30 viscosity index improver polymer and at least one polyalkylene glycol as defined previously,
the quantity of polyalkylene glycol being from 1 to 28% by mass, with respect to the total
mass of lubricant composition. A quantity less than 1% by mass is insufficient to obtain a
significant effect in terms of fuel savings and engine cleanliness. Similarly, a quantity
5
10
15
20
greater than or equal to 30% does not make it possible to obtain a significant effect in
terms of engine cleanliness and fuel savings. Starting from 30% by mass, the "Fuel Eco"
effects are less marked, or even reduced.
Preferably, the lubricant compositions according to the invention comprise from 2
to 20% by mass of the polyalkylene glycols described above with respect to the total mass
of lubricant composition, more preferably from 3 to 15%, even more preferably from 5 to
12%, even more preferably from 6 to 10%, with an optimum of around 8% by mass in terms
of Fuel Eco properties and engine cleanliness.
Advantageously, the lubricant composition according to the invention may
consisting of:
from 40 to 80% by mass of base oil,
from 1 to 28% by mass of polyalkylene glycol, which is a copolymer
of butylene oxide and propylene oxide with the butylene oxide to
propylene oxide mass ratio being a value of 3:1 to 1:3, preferably a
value of 3: 1 to 1:1, the polyalkylene glycol having the general
formula (A):
Y 1 O
H
C
H
C O Y Jn
R 2x-1 R 2x
25
30
wherein
(A)
Yi and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 to
30 carbon atoms,
n represents an integer greater than or equal to 2, preferably less than 60,
preferably ranging from 5 to 30, preferably ranging from 7 to 15,
x represents one or more integers ranging from 1 to n,
the R2x-i and R2x groups are, independently of each other, hydrogen, or hydrocarbon
radicals, comprising from 1 to 2 carbon atoms,
for at least one value of x, the sum of the numbers of carbon atoms in R2x-i and R2x
is equal to 2,
from 1 to 15% by mass of viscosity index improver polymer,
• from 1 to 15% by mass of additives chosen from the anti wear
additives, detergents, dispersants, anti-oxidants, friction modifiers
alone or in a mixture, the sum of the constituents being equal to
100% and the percentage being expressed with respect to the total
5 mass of lubricant composition.
Viscosity index improver polymers
The polymers used in the compositions according to the present invention are
viscosity index improver polymers. These polymers are polymers well known to a person
10 skilled in the art and are chosen from the group constituted by the copolymers of ethylene
and alpha-olefin, polyacrylates such as polymethacrylates, olefin copolymers (OCP),
copolymers of ethylene, propylene and a diene (Ethylene Propylene Diene Monomers
(EPDM)), polybutenes, copolymers of styrene and olefin, hydrogenated or not, copolymers
of styrene and acrylate.
15 The olefin copolymers are preferably copolymers of ethylene and propylene. The
quantity by mass of ethylene, with respect to the total mass of copolymer, varies from 20
to 80%, preferably from 30 to 70%, and is preferably situated around 50%.
The polyacrylates are preferably polymethacrylates, linear or comb-shaped,
functionalized or non-functionalized. For the functionalized polymethacrylates, the term
20 dispersant polymethacrylates is also used, also denoted PAMAd, which are
polymethacrylates which are grafted or functionalized for example by vinyl pyrrolidone
type units.
The copolymers of styrene and olefin are preferably copolymers of styrene and
butadiene or copolymers of styrene and isoprene, hydrogenated or not, preferably
25 hydrogenated, linear or star-shaped.
Preferably, hydrogenated copolymers of styrene and isoprene are used.
Preferably, hydrogenated copolymers of styrene and isoprene in a mixture with
polymethacrylates (PMA) are used.
Preferably, the mass ratio of the hydrogenated copolymer of styrene and isoprene
30 to the polymethacrylate varies from 3:1 to 1:3, and is preferably equal to 1:1.
The lubricant compositions according to the invention comprise from 1 to 15% by
mass of viscosity index improver polymer, or a mixture of viscosity index improver
polymers, with respect to the total mass of lubricant composition, preferably from 2 to
10%, more preferably from 3 to 8%.
Base oils
5 The lubricant compositions according to the present invention can comprise, in
combination with the PAG as described above, one or more other base oils, which can be
oils of mineral or synthetic origin of Groups I to V according to the classes defined in tie API
classification (or their equivalents according to the ATIEL classification) as summarized
below, alone or in a mixture. Moreover, the base oil(s) used in the lubricant compositions
10 according to the present invention can be chosen from the oils of synthetic origin of (Iiroup
VI according to the ATIEL classification.
Group 1 Mineral oils
Group II Hydrocracked oils
Group III
Hydrocracked or hydroisomerized
oils
Group IV
Group V
Group VI*
Saturates content
<90%
> 90 %
>90%
Sulphur
content
> 0.03 %
< 0.03 %
< 0.03 %
Viscosity
index (VI)
80 < VI < 120
80120
Polyalphaolefins (PAO)
Esters and other bases not included in bases of
Groups 1 to IV
(PIO) Poly Internal Olefins
* for the ATIEL classification only
15 These oils can be oils of vegetable, animal, or mineral origin. The mineral base oils
in the compositions according to the invention include all types of bases obtained by
atmospheric and vacuum distillation of crude oil, followed by refining operations sich as
solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking; and
hydroisomerization, hydrofinishing.
20 The base oils in the compositions according to the present invention can also be
synthetic oils, such as certain esters of carboxylic acids and alcohols, GTL bases which can
be obtained by hydroisomerization of a Fisher-Tropsch wax, or polyalphaolefins. The
polyalphaolefins used as base oils are for example obtained from monomers having 4 to 32
carbon atoms (for example octene, decene), and have a viscosity at 100°C comprised
between 1.5 and 15 cSt. Their average molecular mass by weight is typically comprised
5 between 250 and 3000.
Preferably, the lubricant compositions according to the present invention have a
kinematic viscosity at 100°C comprised between 5.6 and 16.3 cSt measured by the standard
ASTM D445, (SAE grade 20, 30 and 40), preferably comprised between 9.3 and 12.5 cSt
(grade 30). According to a particularly preferred embodiment, the compositions according
10 to the present invention are multigrade oils, of grade 5W or OW according to the SAILI300
classification.
The compositions according to the present invention also preferably heve a
viscosity index (VI) greater than 130, preferably greater than 150, preferably greater than
160 (measured according to the standard ASTM D2270).
15 The lubricant compositions according to the invention comprise from 40 to 80% by
mass of base oil with respect to the total mass of lubricant composition, preferably from 50
to 75% by mass, more preferably from 60 to 70%.
Other additives
20 The lubricant compositions according to the invention can also contain all types of
additives suitable for their use, in particular as engine oil, preferably for motor vehicle
engines.
These additives can be added individually, or in the form of additive packages,
guaranteeing a certain level of performance to the lubricant compositions, as required, for
25 example by the ACEA (European Automobile Manufacturers' Association). These are for
example and non-limitatively:
- Dispersants, such as for example succinimides, succinimide derivatives such as PIB
(polyisobutene) succinimides, or Mannich bases, which ensure that the insoluble
solid contaminants constituted by the by-products of oxidation which are formed
30 when the engine oil is in service, are maintained in suspension and removed.
- Antioxidants which slow down the degradation of the oils in service, degradation
which can lead to 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. Among the commonly used antioxidants, sterically hindered phenolic
and amino-type antioxidants are found. Another class of antioxidants is that of
oil-soluble copper compounds, for example copper thio- or dithiophosphates,
copper salts of carboxylic acids, copper dithiocarbamates, sulphonates, phenates,
5 acetylacetonates. Copper (I) and (II) salts of succinic acid or anhydride are also
used.
- Anti-wear additives which protect the friction surfaces by forming a protective
film adsorbed on these surfaces. Various phosphorus-, sulphur-, nitrogen-,
chlorine- and boron-containing compounds are also found in this category.
10 - Friction modifiers such as MoDTC, fatty amines or the esters of fatty acids and
polyols such as the esters of fatty acids and glycerol, in particular glycerol
monooleate.
- Detergents which are typically sulphonates, salicylates, naphthenates, phenates,
overbased or neutral carboxylates.
15 - And also anti-foaming agents, pour point depressants, corrosion inhibitors etc.
Another subject of the invention is a method for lubricating at least one mechanical
part of an engine comprising at least one step in which said mechanical part is brought into
contact with at least one lubricant composition as defined above. These parts are in
20 particular the pistons.
The method according to the invention makes it possible to simultaneously obtain
satisfactory engine cleanliness and a reduction in the fuel consumption of said vehicles,
All the characteristics and preferences for the lubricating composition shown also
applies to the lubrication method of the invention.
25
Another subject of the present invention advantageously concerns the use of at
least one polyalkylene glycol, which is a copolymer of butylene oxide and propylene oxide
with the butylene oxide to propylene oxide mass ratio being a value of 3:1 to 1:3 ,
preferably a value of 3:1 to 1:1 in a lubricant composition in order to improve engine
30 cleanliness, without increasing the consumption of gasoline or diesel fuel, preferably in
order to improve engine cleanliness by reducing the consumption of gasoline or diesel fuel,
the polyalkylene glycol having the general formula (A):
Y 1 O 8 H
C O Y
n
5
10
15
R 2x-1 R 2x
(A)
wherein
- Yi and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 to
30 carbon atoms,
- n represents an integer greater than or equal to 2, preferably less than 60,
preferably ranging from 5 to 30, preferably ranging from 7 to 15,
- x represents one or more integers ranging from 1 to n,
- the R2x-i and R2x groups are, independently of each other, hydrogen, or hydrocarbon
radicals, comprising from 1 to 2 carbon atoms,
- for at least one value of x, the sum of the numbers of carbon atoms in R2x-i arid R2x
is equal to 2.
All the characteristics and preferences for the lubricating composition shown applies
equally to the use of at least one PAG of the invention according to the invention.
20
25
30
Examples
Example 1
Control compositions Ti and the compositions Uand L2are prepared from
a mixture of Group III base oils,
an additive package comprising ZnDTP-type anti-wear additives, amino and
phenolic anti-oxidants, succinimide-type dispersants, saUcylate-type detergent.;,
a molybdenum dithiocarbamate (MoDTC),
a star-shaped hydrogenated styrene/isoprene (HIS) viscosity index imp over
polymer, with a mass Mw equal to 498700 (measured according to the standard
ASTM D5296), with a mass Mn equal to 325900 (measured according to the
standard ASTM D5296), with a polydispersity index equal to 1.5.
a polyalkylmethacrylate grafted with vinyl pyrrolidone units (PAMAd), with a mass
Mw equal to 206900 (measured according to the standard ASTM D5296), with a
mass Mn equal to 75320 (measured according to the standard ASTM D5296), with a
polydispersity index equal to 2.7,
a BO/PO (butylene oxide/propylene oxide) PAG having a mass ratio of 50/50, with a
KV100 equal to 6 cSt (measured according to the standard ASTM D445) and with a
5 molar mass equal to 750 g/mol measured according to the ASTM D4274 standard.
The proportions in percentage by mass of the different constituents are shown in
Table I below. The proportions of the mixture of base oils and viscosity index improver
polymer are adjusted so that the lubricant compositions T^ Lx and L2 have equivalent
viscosities, for a grade 5W-30.
10 Table I
Mixture of Group III base oils
Additive package
MoDTC
HIS
PAMA
BO/PO PAG
Total
KV100(1)
KV40 (1)
Viscosity index (VI),2)
HTHS (3)
Ti
82.7
10.9
0.5
3.1
2.8
-
100
9.87
48.39
192
2.99
U
74.9
10.9
0.5
2.9
2.8
8
100
9.82
48.75
194
3.04
L2
52.7
10.9
0.5
3.1
2.8
30
100
9.82
49.71
189
3.07
ISO 3104
ISO 2909
CEC L-036
15 The "Fuel Eco" gain of the lubricant compositions Ti, U and L2 is then measured on
a running DW10C test engine. The conditions of this test are as follows:
Different engine speed and load conditions are scanned, during which the specific
fuel consumption is measured. Running speed ranged from 1000 to 2400 rpm. Engine load
ranged from 16 to 190 N.m. The engine oil and cooling liquid are stabilized at different
20 temperatures (45°C, 60°C and 75°C) in order to ensure good repeatability of the
measurement. For each point, the specific fuel consumption of the lubricant to be tested is
compared with that of a 5W-30 reference oil. A weighted average makes it possible to
express as a percentage the overall gain provided by the test lubricant with respect to the
reference. The gains in terms of fuel consumption of the lubricant compositions Tlt Lx c nd L2
are given in Table II, expressed in % with respect to a reference oil of grade 5W-30.
5 The cleanliness of the engine is also measured by means of the Panel Coking; Test
(PCT) laboratory test under the following experimental conditions:
The lubricant to be tested flows over an inclined metal plate heated to 288°C with a
flow rate of ImL/min. A volume of oil of 100 mL is pumped over this plate in a closed c ircuit
for a 24h test period. At the end of the test, the plate is rinsed with a solvent and the
10 varnish and carbon deposits on the flow surface are rated by means of a CRC (Coordirating
Research Council) rating method. The result is expressed in the form of a score from 0 to 10
corresponding to the state of cleanliness of the plate.
The cleanliness of the engine is also measured by means of the TDi engine test
according to the method CEC L-78-99 which measures in particular the cleanliness of the
15 pistons.
The cleanliness results for the lubricant compositions Ti, La and L2 are given in Table
II.
Table II
Weighted gain
PCT
CEC L-78-99 Tdi
Ti
0.8
7.7
54 (reference 64)
Li
1.0
8.7
67 (reference 65)
L2
0.8
9.0
-
It is found that the addition of 8% of BO/PO PAG to a lubricant composition makes
20 it possible to improve the gain in terms of fuel consumption and cleanliness, with isoviscosity
and for a smaller quantity of viscosity index improver polymer. The addition of
30% of BO/PO PAG to a lubricant composition makes it possible to improve engine
cleanliness but with no change in gain in terms of fuel consumption.
25 Example 2
A control composition T2 and compositions C2 to C4 are prepared from the same
constituents as above, but with another polyalkylene glycol: a BO/PO PAG having a mass
ratio of 50/50, KV100 equal to 4 cSt (measured according to the standard ASTM D445) and
molar mass equal to 505 g/mol (measured according to the standard ASTM D4274).
The proportions in percentage by mass of the different constituents are shown in
Table Ml below. The proportions of the mixture of base oils and viscosity index improver
polymer are adjusted so that the lubricant compositions T2, Cx to C4 have equivalent
viscosities, for a grade 5W-30.
5 The "Fuel Eco" gain of the lubricant compositions T2, Ci to C4 is then measurec on a
driven DW10C test engine. The conditions of this test are as follows:
The engine is driven by means of a generator making it possible to impose a speed
of rotation of between 750 and 3000 rpm while a torque sensor makes it possifcle to
measure the friction torque generated by the movement of the engine parts. The engiie oil
10 and cooling liquid are stabilized at different temperatures (35°C, 50°C, 80°C and 115 C) in
order to ensure good repeatability of the measurement. The friction torque induced by the
test lubricant is compared for each speed and each temperature with the torque incuced
by the reference lubricant of grade 5W-30. The final result obtained by the test lubricant is
obtained via the average of the gains on each operating point expressed with respect to the
15 reference lubricant. A positive gain means that there is less friction in the engine anc that
the lubricant used makes it possible to reduce fuel consumption.
Table III
Mixture of Group III base
oils
Additive package
MoDTC
HSI
PAMA
PO/BO PAG
Total
KV100 (1)
KV40 (1)
Viscosity index (VI)(2)
HTHS (3
Average FEgain
T2
83.1
10.9
0.5
2.8
2.7
-
100
9.96
50.43
189
3.09
2.2
Ci
78.9
10.9
0.5
2.9
2.8
4
100
9.86
51.50
181
2.98
2.4
c2
74.9
10.9
0.5
2.9
2.8
8
100
9.85
51.31
181
3.03
3.1
c3
67.9
10.9
0.5
2.9
2.8
15
100
9.95
51.46
184
3.06
2.1
c4
52.8
10.9
0.5
2.9
2.9
30
100
9.79
49.84
187
3.07
1.9
ISO 3104
ISO 2909
l°' CEC L-036
It is found that the addition of 4% or 8% of BO/PO PAG makes it possible to improve
the gain in terms of fuel consumption of these compositions. Quantities greater than 15%
or 30% provide the same gain as the control composition.

Amended claims (Article 19 PCT)
1. Lubricant composition for engines comprising at least one base oil, at least one viscosity
index improver polymer and at least one polyalkylene glycol, which is a copolymer of
butylene oxide and propylene oxide with the butylene oxide to propylene oxide mass ratio
being a value of 3:1 to 1:3, preferably a value of 3:1 to 1:1, the quantity of polyalkylene glycol
being from 2 to 20% by mass with respect to the total mass of lubricant composition, the
polyalkylene glycol having the general formula (A):
Y 1 O
H
C
R 2x-1
H c
R 2x
n
O Y
(A)
wherein
2
3
4
5
Yi and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 to 30
carbon atoms,
n represents an integer greater than or equal to 2, preferably *ess t t e ^ 60# preferably
ranging from 5 to 30, preferably ranging from 7 to 15,
x represents one or more integers ranging from 1 to n,
the R2x-i and F*2x groups are, independently of each other, hydrogen, or hydrocarbon rad icals,
comprising from 1 to 2 carbon atoms,
for at least one value of x, the sum of the numbers of carbon atoms in R2x_i and R2x is equal
to 2.
Lubricant composition according to claim 1 in which the polyalkylene glycol has a molar mass
measured according to the standard ASTM D4274 ranging from 300 to 1000 grams per mole,
preferably from 500 to 750 grams per mole.
Lubricant composition according to any one of claims 1 to 2 in which the polyalkylene glycol
has a kinematic viscosity at 100°C measured according to the standard ASTM D445
comprised between 1 and 12 cSt, preferably between 3 and 7 cSt, more preferably between
3.5 and 6.5 cSt.
Lubricant composition according to any one of claims 1 to 3 comprising from 3 to 15% by
mass of polyalkylene glycol with respect to the total mass of the lubricant composition,
preferably from 5 to 12%, more preferably from 6 to 10%.
Lubricant composition according to any one of claims 1 to 4 in which the viscosity index
improver polymer is selected from the group consisting of the olefin copolymers, the
ethylene/alpha-olefin copolymers, styrene/olefin copolymers, the polyacrylates alone cr in a
mixture.
Lubricant composition according to any one of claims 1 to 5 comprising from 1 to 11% by
mass of polymer with respect to the total mass of the lubricant composition, preferably from
2 to 10%, more preferably from 3 to 8%.
Lubricant composition according to any one of claims 1 to 6 further comprising at least one
additive chosen from the anti-wear additives, detergents, dispersants, anti-oxidants, friction
modifiers alone or in a mixture.
Lubricant composition according to any one of claims 1 to 7 consisting of:
• from 40 to 80% by mass of base oil,
• from 2 to 20% by mass of polyalkylene glycol, which is a copolymer of
butylene oxide and propylene oxide with the butylene oxide to propylene
oxide mass ratio being a value of 3:1 to 1:3, preferably a value of 3 :1 to 1:1,
the polyalkylene glycol having the general formula (A)
H H
Y, 1 O C C 1 O Y2
R a M R2x (A)
rein
Yi and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 lo 30
carbon atoms,
n represents an integer greater than or equal to 2, preferably less than 60, preferably
ranging from 5 to 30, preferably ranging from 7 to 15,
x represents one or more integers ranging from 1 to n,
the R2x-iand R2x groups are, independently of each other, hydrogen, or hydrocarbon radicals,
comprising from 1 to 2 carbon atoms,
for at least one value of x, the sum of the numbers of carbon atoms in R2x-i and R2x is equal
to 2,
• from 1 to 15% by mass of viscosity index improver polymer,
• from 1 to 15% by mass of additives chosen from the anti-wear addiives,
detergents, dispersants, anti-oxidants, friction modifiers alone or in a
mixture, the sum of the constituents being equal to 100% and the
percentage being expressed with respect to the total mass of lubricant
composition.
Use of a lubricant composition according to any one of claims 1 to 8 for the lubrication of a
light or heavy vehicle engine, preferably of light gasoline or diesel vehicles.
10. Use of at least one polyalkylene glycol, which is a copolymer of butylene oxide and propylene
oxide with the butylene oxide to propylene oxide mass ratio being a value of 3:1 to 1:3 ,
preferably a value of 3:1 to 1:1 in a lubricant composition in order to improve engine
cleanliness, without increasing the consumption of gasoline or diesel fuel, preferably in order
to improve engine cleanliness by reducing the consumption of gasoline or diesel fuei, the
polyalkylene glycol having the general formula (A):
r H H i
Y, O C C O Y2
R2x-1 R2x
(A)
wherein
- Yi and Y2 are, independently of each other, hydrogen, or an alkyl group having 1 io 30
carbon atoms,
n represents an integer greater than or equal to 2, preferably less than 60, preferably
ranging from 5 to 30, preferably ranging from 7 to 15,
x represents one or more integers ranging from 1 to n,
- the R2x-:i and R2x groups are, independently of each other, hydrogen, OT hydrocarbon radicals,
comprising from 1 to 2 carbon atoms,
for at least one value of x, the sum of the numbers of carbon atoms in R2x-i and R2x is equal
to 2.
11. Use according to claim 10 in order to improve engine cleanliness, in particular the cleanliness
of the pistons.