Note: Descriptions are shown in the official language in which they were submitted.
CA 02667583 2014-02-27
MULTIFUNCTIONAL LUBRICATING FLUID COMPRISING
TWO OR MORE POLYMERS
Field of the invention
The present invention relates to multifunctional lubricating fluids for use in
the
various mechanisms of motor vehicles, in particular in the engine, the
transmission or
the hydraulic circuit. More precisely, the invention relates to a single fluid
that can be
used directly in several types of applications, in particular in the various
mechanisms
of motor vehicles such as engines, transmission devices (gearboxes and
transfer
boxes), hydraulic circuits and other ancillary mechanisms without any need for
modification; in other words, the composition of this fluid is directly
suitable for the
various types of use in question.
Background of the invention
At present every motor vehicle uses a variety of monoftinctional lubricating
fluids,
each fulfilling different functions, for example engine oils, gearbox oils,
hydraulic oils
etc.
The formulation of a monofunctional oil consists conventionally of a mixture
of
mineral. semi-synthetic or synthetic base oils, a package of performance
additives,
and optionally a viscosity improving polymer and a pour point improver.
When a monofunctional lubricating oil is in service in a mechanism, the
constant
shear to which the viscosity improving polymer is subjected leads to a
decrease in
viscosity of the oil. The extent and rate of this decrease in viscosity depend
on the
nature and amount of viscosity improving polymer used.
Now, the shear rates to which the lubricant is subjected differ from one
mechanism to another. For example, the high-pressure hydraulic circuits
operating the
lifting mechanisms produce more shear than the gearboxes, and they in tum
produce
more shear than the engines.
If a monotiinctional oil is used in a mechanism other than that for which it
has
been formulated, its viscosity may move away from the value required for
optimum
functioning of said mechanism.
Formulations of multifunctional oils for engine, gearbox and hydraulic circuit
are
already marketed under the names TOTAL Multi TP, F1NA Penta, ELF Noria. Their
*Trademark
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design is based on an appropriate choice of viscosity improving polymer and
the
amount incorporated.
The varying level of shear stability of the viscosity improving polymer
incorporated in these multifunctional oils for engine, gearbox and hydraulic
circuit
will determine the respective levels of viscosity attained by this oil in each
mechanism.
If we use a viscosity improving polymer that is very sensitive to shear, the
viscosity will drop very rapidly, even in those mechanisms having a low shear
rate: it
will drop below the minimum viscosities required in the engine and the
gearbox.
Conversely, if we use a polymer with a very high shear stability, the
viscosity will
remain high for a very long time even in those mechanisms having a high shear
rate: it
will take a very long time before the viscosity reaches in the best case a low
enough
value, as required for example in the hydraulic circuits. This can cause
persistent cold
starting problems for the lifting mechanisms operated by the hydraulic
circuit.
If the behaviour of the polymer is intermediate, the adjustment parameters
allowing simultaneous fulfilment of the 3 constraints of minimum viscosities
in
engine and gearbox, and maximum viscosity in the hydraulic system, are the
amount
and nature of the viscosity improving polymer used.
Most of the multifunctional oils currently in use are based on this principle.
We
therefore end up with compromises that exceed the limits of capacity for use
of the
existing multifunctional oils in three mechanisms at the same time.
Thus, the existing formulations of multifunctional oils do not allow them to
simultaneously reach the performance levels expected in the various target
mechanisms. Moreover, the performance levels are also not achieved in
particular
with respect to the high-temperature stability in the engines and the
transmission and
the cold starting of the hydraulics.
There is therefore a need for a single fluid whose performance is suitable for
lubricating various mechanisms of a vehicle at the same time. In particular,
there is a
need for a single fluid that can be used for all three applications: engine,
transmission
and hydraulic circuit. There is also a need for the performance of this same
single
fluid to be adapted for good high-temperature stability in the engine and
transmission
and for cold starting of the hydraulics.
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In fact, having a single fluid available for lubricating various mechanisms of
a
vehicle, relative to the use of several monofunctional oils, offers advantages
in
particular in terms of ease of maintenance and storage, servicing of the
vehicle or of a
fleet of vehicles, packaging and logistics.
This is true in particular for the large fleets of public service vehicles,
which are
often used on isolated sites and are subject to severe weather conditions,
without
adequate storage equipment.
Summary of the invention
Thus, the invention provides a lubricating composition comprising at least one
oil
of groups I to V and a mixture of at least two polymers having a difference in
permanent shear stability index (PSSI), measured after the standardized KRL 20
hours
test at 100 C of at least 25, and having a viscosity profile such that
(a) at 100 C after the Bosch-30 cycles test according to standard CEC-L-14-A-
93
the viscosity of the final lubricating composition is greater than 9.0 cSt,
preferably
in the range from 9.0 to 12.0 cSt for an oil initially of grade 30, or else
the
viscosity of the final lubricating composition is greater than 12.0 cSt,
preferably in
the range from 12.0 to 15.0 cSt for an oil initially of grade 40, and
(b) at 100 C after the KRL-20 hours test according to standard CEC-L-45-A-99
the viscosity of the lubricating composition is greater than 8.5 cSt,
preferably in
the range from 8.5 to 11.0 cSt for an oil initially of grade 30 or 40, and
(c) at 40 C after the KRL-3 hours test, according to standard CEC-L-45-A-99
with
the test duration reduced to 3 hours, the viscosity of the lubricating
composition is
less than 51 cSt, preferably in the range from 41 to 51 cSt for an oil
initially of
grade 30 or 40.
This formulation of multifunctional lubricant can be used for simultaneously
lubricating various mechanisms of a motor vehicle. More particularly, this
single
lubricant is used for simultaneously lubricating at least three mechanisms,
namely the
engine, the gearbox and the hydraulic circuit, as it offers a viscosity
profile adapted to
the conditions of use required in each target mechanism.
For simultaneously lubricating the various target mechanisms of a motor
vehicle,
this single lubricant incorporates a mixture of polymers having different
shear
stabilities.
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The nature and the respective amount of the different types of polymers are
determined in such a way that the lubricating composition incorporating this
mixture
adapts very rapidly to the conditions of use required in each target
mechanism, owing
to its viscosity profile.
Thus, the lubricating composition includes at least 50 wt.%, based on the
weight
of the final composition, of at least one oil selected from the oils of groups
I to V and
at least 5%, preferably from 5 to 40%, or more preferably 5 to 15 wt.% based
on the
weight of the final composition, of a mixture comprising at least two
different
polymers of type "A", "B", or "C", the polymers of the mixture differing from
one
another in that they belong to a separate range of permanent shear stability
index
(PSSI) such that:
-the polymers of type "A" have a permanent shear stability index (PSSI),
measured after the standardized KRL 20 hours test at 100 C, less than or equal
to 40,
-the polymers of type "B" have a permanent shear stability index (PSSI),
measured after the standardized KRL 20 hours test at 100 C, between 40 and 65
exclusive;
-the polymers of type "C" have a permanent shear stability index (PSSI),
measured after the standardized KRL 20 hours test at 100 C, greater than or
equal to
65;
said composition in which at least two polymers have a difference in PSSI
measured after the standardized KRL 20 hours test at 100 C, of at least 25.
According to an embodiment, each of the polymers of the mixture is obtained
from monomer units of a different chemical nature.
According to another embodiment, each polymer of the mixture is obtained from
monomer units of identical chemical nature, and the polymers of the mixture
differ
from one another in that they belong to a different range of permanent shear
stability
index (PSSI) measured after the standardized KRL 20 hours test at 100 C and by
at
least one physicochemical characteristic selected from the number-average or
weight-
average molecular weight, the molecular weight distribution of said polymer
characterized by the polydispersity index, the morphology of the three-
dimensional
network of said polymer characterized by its degree of crosslinking and/or
branching.
CA 02667583 2009-04-24
According to an embodiment, the mixture comprises at least two polymers, the
amount of one polymer relative to the total weight of the polymer mixture
ranging
from 10% to 90%.
According to an embodiment, the mixture comprises two polymers, one of type A
5 and the other of type C, wherein, preferably, the weight ratio of the
mixture of the two
polymers A/C ranges from 10/90 to 90/10.
According to an embodiment, the lubricating composition according to the
invention additionally comprises from 5 to 30 wt.%, relative to the weight of
the final
composition, of a package of functional additives and optionally less than 1
wt.%,
preferably from 0.2% to 0.5 wt.%, relative to the weight of the final
composition, of a
pour point improver.
According to an embodiment, the polymers of the mixture are selected from
polymers of the viscosity improver type and optionally from polymers of the
pour
point improver type.
Preferably, the viscosity improving polymers are selected from poly-alpha-
olefins
(PAO) with a kinematic viscosity at 100 C greater than 90 cSt, poly-isobutenes
(PIB),
polymeric esters, olefin copolymers (OCP), homopolymers or copolymers of
styrene,
of butadiene or of isoprene, polymethacrylates (PMAs).
Preferably, the pour point improving polymers are selected from
polymethacrylates (PMAs).
Preferably, the polymers of type A are viscosity improving polymers selected
from polymethacrylates, poly-alpha-olefins with a kinematic viscosity at 100 C
greater than 90 cSt, polyisobutenes, polymeric esters.
Preferably, the polymers of type C are viscosity improving polymers selected
from polymethacrylates, olefinic copolymers, hydrogenated styrene-isoprene
copolymers, copolymeric esters.
Preferably, the polymers of type B are viscosity improving polymers of the
polymethacrylate type.
According to another aspect the invention relates to a method of making a
lubricating composition according to the invention wherein a mixture
comprising at
least two different polymers is incorporated in at least one oil of groups I
to V
optionally comprising a package of additives and optionally a pour point
improver.
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According to an embodiment, at least one of the polymers of the mixture is a
viscosity improver, which is incorporated directly in the composition as a
separate
compound, independently of the package of additives.
According to another embodiment of the method, all or part of at least one of
the
viscosity improving polymers of the mixture is incorporated in the composition
as an
element of the package of additives.
According to another embodiment of the method, all or part of at least one of
the
viscosity improving polymers of the mixture is incorporated in the composition
in the
form of a diluent of the package of additives.
According to another aspect the invention relates to the use of a lubricating
composition according to the invention as a single fluid for lubricating
various
mechanisms of motor vehicles.
Preferably, the single fluid is used for lubricating at least three mechanisms
of
motor vehicles, the engine, the gearbox and the hydraulic system of the
vehicle.
More preferably, the single fluid is also used for lubricating the circuit for
operating the brakes, the on-board compressor and optionally other ancillary
mechanisms.
Detailed description of the embodiments of the invention
(A) Determination of shear stability:
The shear stability of a compound in an oil is characterized by the PSSI
(Permanent Shear Stability Index), defined in standard ASTM-D6022-06 and
calculated from the kinematic viscosities of said compound in the oil before
and after
a defined shearing process.
The formula for the PSSI of a polymer in an oil is given by:
PSSI = 100 x (Vi - Vc)/(Vi - Vo),
where:
= Vi = initial viscosity before shear of the oil + polymer mixture at 100
C.
= Vc = viscosity of the oil + polymer mixture after a shearing process at
100 C.
= Vo = initial viscosity before shear of the oil alone at 100 C.
Thus, the higher the PSSI of a polymer in the reference oil, the more said
polymer
is said to be sensitive to shear.
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The shearing process selected for determining the PSSI of the polymers
according
to the present invention is the KRL 20 hours test, according to standard CEC-L-
45-A-
99.
The reference oil selected for measuring the PSSI of the polymers according to
the
present invention is a base oil from group III (according to the API
classification)
with a viscosity of 4.2 cSt at 100 C.
Hereinafter, and unless otherwise stated, the PSSI of a polymer will be the
PSSI
measured according to standard ASTM-D6022-06, measured in a diluent oil of
group
III (according to the API classification and with a viscosity of 4.2 cSt at
100 C, after
the KRL 20 hours test, according to standard CEC-L-45-A-99).
In order to determine the composition of the mixtures of polymers incorporated
in
the lubricants according to the present invention, the applicant has defined
the
shearing conditions representative of each of the mechanisms considered and
the
levels of viscosity appropriate to each mechanism.
(B) Determination of the viscosity profile
1. Conditions of use as engine oil:
For engine lubricants, the CEC-L- 14-A-93 (or ASTM D6278) standard defines
the test representative of the shearing conditions in the engine, known as the
Bosch-30
cycles test.
The SAE J 300 classification defines the viscosity grades of fresh engine oils
in
particular by measurement of their kinematic viscosities at 40 C and/or 100 C.
An engine oil is of grade 30 according to SAE J 300 if its kinematic viscosity
at
100 C is from 9.3 to 12.5 cSt.
An engine oil is of grade 40 according to SAE J 300 if its kinematic viscosity
at
100 C is from 12.5 to 16.3 cSt.
Engine oils of grade 30 or 40 are generally used in so-called temperate
climates.
An engine oil is of grade 50 according to SAE J 300 if its kinematic viscosity
at
100 C is between 16.3 and 21.9 cSt. This type of oil is generally used in so-
called hot
climates.
As for the ACEA standards, they define in detail a certain number of
supplementary specifications for engine oils, and in particular stipulate the
maintaining of a certain level of viscosity for oils subjected in operation to
shear in
the engine.
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Thus, according to ACEA series E2 or E3 the kinematic viscosity of engine oils
of
grade 30, 40 and 50, measured at 100 C, after the Bosch-30 cycles test, must
be
greater than 9.0, 12.0 and 15.0 cSt, respectively.
The lubricants according to the present invention that are usable as engine
lubricants have a kinematic viscosity at 100 C greater than 9.0 cSt,
preferably in the
range from 9.0 to 12.0 cSt after the Bosch-30 cycles test according to the CEC-
L- 14-
A-93 standard for an oil initially of grade 30. These lubricants have a
kinematic
viscosity at 100 C greater than 12.0 cSt, preferably in the range from 12.0 to
15.0 cSt
after the Bosch-30 cycles test according to the CEC-L-14-A-93 standard for an
oil
initially of grade 40. After this same test, these lubricants have a kinematic
viscosity
at 100 C which is greater than 15.0 cSt, preferably in the range from 15.0 to
20.0 cSt
for an oil of grade 50.
2. Conditions of use as gearbox oil:
For gearbox lubricants, the CEC-L-45-A-99 standard defines the test
representative of the shearing conditions in the gearbox, known as the KRL 20
hours
test.
The applicant determined, from the data of tests for monitoring oils in
service, that
a viscosity of a lubricant at 100 C after the standardized KRL 20 hours test
greater
than 8.5 cSt was suitable for use in gearboxes in a temperate climate.
Furthermore, a
viscosity of a lubricant at 100 C after the standardized KRL 20 hours test
greater than
11.0 cSt was suitable for use in a hot climate.
3. Conditions of use as hydraulic circuit oil:
The applicant also determined that the shearing conditions to which a
lubricant is
subjected in a hydraulic circuit could be represented by the KRL test
according to the
CEC-L-45-A-99 standard.
The applicant noticed that for operation in the hydraulic circuit while
avoiding the
problem of starting with fresh oil, in particular at low temperature, the
viscosity of the
lubricant, measured at 40 C, should be less than 51 cSt for temperate climates
after
the KRL test according to the CEC-L-45-A-99 standard, the duration of which is
reduced from 20 hours to 3 hours. Similarly, the viscosity of the lubricant
should be
less than 75 cSt for hot climates after the KRL test according to the CEC-L-45-
A-99
standard, the duration of which is reduced from 20 hours to 3 hours.
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Thus, the lubricating compositions according to the present invention are
suitable
simultaneously for use in engines, gearboxes, and hydraulic circuits, as they
have a
viscosity profile which meets the following three cumulative conditions:
(a) at 100 C after the Bosch-30 cycles test according to the CEC-L-14-A-93
standard the viscosity of the final lubricating composition is greater than
9.0 cSt,
preferably in the range from 9.0 to 12.0 cSt for an oil initially of grade 30,
or else the
viscosity of the final lubricating composition is greater than 12.0 cSt,
preferably in the
range from 12.0 to 15.0 cSt for an oil initially of grade 40, and
(b) at 100 C after the KRL 20 hours test according to the CEC-L-45-A-99
standard the viscosity of the lubricating composition is greater than 8.5 cSt,
preferably
in the range from 8.5 to 11.0 cSt for an oil initially of grade 30 or 40, and
(c) at 40 C after the KRL 3 hours test, according to the CEC-L-45-A-99
standard,
the test duration of which is reduced to 3 hours, the viscosity of the
lubricating
composition is less than 51 cSt, preferably in the range from 41 to 51 cSt for
an oil
initially of grade 30 or 40.
Under these conditions, these compositions are particularly suitable for
temperate
climates.
According to a particular embodiment the lubricating compositions according to
the present invention can also be used in hot climates and also meet the
following
conditions:
(1) the viscosity of said composition, measured at 100 C, after the Bosch-30
cycles test according to the CEC-L-14-A-93 standard representative of the
shearing
conditions in the engine, is between 15.0 and 20.0 cSt for a grade 50;
(2) the viscosity of said composition, measured at 100 C after the KRL 20
hours
shearing test according to the CEC-L-45-A-99 standard representative of the
shearing
conditions in the gearbox, is between 11.0 and 14.0 cSt for an oil initially
of grade 50;
(3) the viscosity of said composition measured at 40 C after the KRL 3 hours
shearing test, according to the CEC-L-45-A-99 standard, is between 61 and 75
cSt for
an oil initially of grade 50.
These conditions are determined by measurements of kinematic viscosity
expressed in centistokes cSt (or equivalent mm2/s) and according to known
methods
for which the standards were referred to earlier in the text.
(C) The base oils:
CA 02667583 2009-04-24
The base oils used in the formulation of lubricants according to the present
invention are oils of groups I to V according to the API classification, of
mineral,
synthetic or natural origin, used alone or in mixture, one of the
characteristics of
which is insensitivity to shear, i.e. their viscosity does not change under
shear. In the
5 composition
they represent at least 50 wt.%, relative to the total weight of the final
composition. Moreover, their content can represent up to 95% or even 98% in
the
final composition.
(D) The package of additives:
The packages of additives used in the lubricating formulations according to
the
10 invention are
conventional and are known by the skilled person and meet performance
levels defined by, among others, the ACEA (Association des constructeurs
Europeens
d'Automobiles ¨ "European Automobile Manufacturers' Association") and/or the
API
(American Petroleum Institute).
They contain in particular and non-limitatively:
= antioxidants preventing degradation of the oil (for example amine or
phenolic
derivatives)
= antiwear and extreme-pressure agents protecting the rubbing surfaces by
chemical reaction with the metallic surface (for example zinc
dithiophosphate),
= dispersants ensuring that insoluble solid contaminants (for example PIB-
succinimide) are kept in suspension and are removed,
= detergents, whether superbasic or not, preventing the formation of
deposits on
the surface of metal parts by dissolution of oxidation and combustion by-
products
(for example salicylates, phenates or sulphonates).
and at least 30 wt.% of a diluent consisting of base oil and optionally
viscosity
improving polymer.
The percentage by weight of the package of additives based on the weight of
the
final composition according to the invention is at least 5%, the diluent being
included
in this percentage.
(E) Compounds known as "pour point improvers"
The lubricating formulations according to the invention optionally comprise a
pour point improver, which can be selected from the polymethacrylate (PMA)
group
with molecular weights generally between 5000 and 10000 daltons. It should be
noted
that these PMAs, when they are used as pour point improving additives, are
typically
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present in the lubricating composition at a content of the order of 0.2 wt.%,
based on
the weight of the final lubricating composition. These pour point improving
additives
are generally supplied in the form of formulations diluted to a varying extent
in a base
oil. In particular, when these formulations are not very dilute, the PMAs are
present at
a content of the order of 60%.
Their use in the polymer mixture according to the present invention for
adjusting
the viscosity of the lubricant to a certain level after shear may require the
use of
higher contents.
(F) The polymer mixture in the lubricating composition.
The viscosity profile previously mentioned is in particular obtained by means
of a
mixture of at least two polymers selected from the polymers of types "A", "B"
or "C"
as defined below:
The polymers of types "A", "B" or "C" used as a mixture in the lubricants
according to the present invention are preferably selected from polymers that
improve
the viscosity index or improve the pour point, as described above.
The viscosity improving polymers used in the present invention correspond to
those used in the monofunctional oils. They are preferably selected from poly-
alpha-
olefins (PAO) with a kinematic viscosity at 100 C greater than 90 cSt, poly-
isobutenes (PIB), polymeric esters, olefinic copolymers (OCP), homopolymers or
copolymers of styrene, of butadiene or of isoprene, polymethacrylates (PMA).
The pour point improving polymers used in the present invention are preferably
selected from polymethacrylates (PMA).
In general, the purpose of a viscosity improving polymer is to reduce the
viscosity
variations of the lubricant with the temperature. This temperature behaviour
is
characterized by the viscosity index V.I. of the lubricant. For an oil of high
V.I. the
stability of its viscosity as a function of temperature will be better.
The polymers incorporated in the lubricants according to the present invention
have been classified in three groups according to the particular range of PSSI
to which
they belong:
1) The group of polymers of type "A" comprises the polymers that have a
permanent shear stability index (PSSI), measured after the standardized KRL 20
hours
test at 100 C, less than or equal to 40. These polymers have little
sensitivity to shear:
they are polymers whose PSSI after the standardized KRL 20 hours test at 100 C
is
CA 02667583 2014-02-27
12
less than or equal to 40, preferably from 0 to 20. This type of polymer will
make it
possible to maintain the viscosity at a sufficient level in the engine and in
the gearbox,
but will also allow the viscosity to drop considerably in the hydraulic
system.
The group of polymers of type "A" will include, in particular and non-
limitatively,
viscosity improving polymers selected from viscous poly-alpha-olefins (PAO)
(with a
viscosity at 100 C greater than 90 eSt), polyisobutenes (NB),
polymethacrylates
(PMA). More specifically the polymers of type A are viscosity improving
polymers
selected from the polymethaerylates (Viscoplex 0-030, (>-110, 6-054, 8-220, 12-
310),
viscous poly-alpha-olefins (Spectrasyn 1000,300,150), polyisobutenes (lndopole
2100, Lubrizol 3174), polymeric esters (Kenjetlube 2700).
2) The group of polymers of type "B" comprises polymers that have a permanent
shear stability index (PSS1), measured after the standardized KRL 20 hours
test at
100 C. between 40 and 65 exclusive. These polymers of intermediate behaviour
are
said to be sensitive to shear: they are polymers whose PSSI after the
standardized
KRL 20 hours test at 100 C is between 40 and 65 exclusive. This type of
polymer will
provide the extra viscosity improver if necessary.
The group of polyiners of type "B" includes in particular the viscosity
improving
polymers of the polymethacrylate type (Viscoplex 0-22(>, 3-500, 8-400, 8-251,
3-310).
3) The group of polymers of type "C" comprises polymers that have a permanent
shear stability index (PSSI), measured after the standardized KRL 20 hours
test at
100 C, greater than or equal to 65. These polymers are very sensitive to
shear: they
are polymers whose PSSI after the standardized KRL 20 hours test at 100 C is
greater
than or equal to 65, preferably from 65 to 100. This type of polymer will be
sheared
very rapidly in the hydraulic system, with a subsequent, long-lasting drop in
viscosity
of the lubricant in said system, thus avoiding the problems of low-temperature
starting.
The group of polymers of type "C" includes, in particular and non-
limitatively, the
viscosity improving polymers selected from the category of olefinic
copolymers,
homopolymers or copolymers of styrene. of butadiene, or of isoprene. More
specifically the polymers of type C are viscosity improving polymers selected
from
aim
polymethacrylates (Viscoplex 7-710), olefinic copolymers (Paratone 8006,
Lubrizol
7077), hydrogenated styrene-isoprene copolymers (Shellvis 151, 701, 261 and
301),
copolyincric esters (Lubrizol 3702).
*Trademark
CA 02667583 2009-04-24
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Thus, the viscosity profile of the composition according to the invention is
obtained when at least two polymers of the mixture are selected from different
ranges
of PSSI.
The polymer mixtures used in the invention are constituted by at least two
polymers, the polymers in the mixture differing from one another in that they
belong
to a different range of permanent shear stability index (PSSI) measured after
the
standardized KRL 20 hours test at 100 C.
This difference is characterized by the existence of a difference in PSSI of
at least
25 between the PSSIs of at least two of the polymers present in the mixture.
Moreover, the resistance to shear of a polymer is not connected exclusively
with
its chemical nature. It can also be connected with physicochemical parameters.
In fact
parameters such as the molecular weights, molecular weight distribution
(characterized in particular by the polydispersity index of the polymer), the
degree of
branching of the polymer chains, and generally the morphological
characteristics of
the polymer have an influence on its resistance to shear. Thus, certain
compounds of
identical chemical nature, such as the polymethacrylates for example, may
belong to
any one of the types "A", "B", or "C" described here.
Accordingly, a person skilled in the art will select the polymers of different
types
for use in the mixture in relation to their classification according to type
A, B or C and
their capacity for producing a lubricating composition, while meeting the
three
cumulative conditions as described above in the target viscosity profile.
This viscosity profile is also obtained when the polymers of the mixture
differ
either in their chemical nature or in their physicochemical nature.
Thus, when the polymers of the mixture differ in their chemical nature, this
differentiation originates from the preparation of the polymers from monomer
units of
a different chemical nature. Thus, for example, a polymethacrylate is
chemically
different from a polyisobutene.
When the polymers of the mixture differ in their physicochemical nature, this
differentiation arises from the preparation of the polymers from monomer units
of
identical chemical nature. In this case, each polymer of the mixture differs
in that it
belongs to a different range of permanent shear stability index (PSSI) as well
as by at
least one physicochemical characteristic selected from the (number-average or
weight-average) molecular weight or the molecular weight distribution of said
CA 02667583 2009-04-24
14
polymer characterized by its polydispersity index or the morphology of the
three-
dimensional network of said polymer characterized by its degree of
crosslinking
and/or branching. These differences in physicochemical nature are utilized
according
to techniques that are well known in the field of polymers.
According to a particular embodiment, the compositions according to the
invention comprise a mixture in all proportions of two polymers of type A/B or
A/C
or B/C. Preferably, in said mixture, the amount by weight of one of the
polymers of
type A or B or C relative to the total weight of polymer in the mixture ranges
from 10
to 90%. According to a preferred embodiment the compositions comprise a
mixture of
two polymers of type A and C in which the weight ratio A/C ranges from 10/90
to
90/10.
According to another particular embodiment the compositions according to the
invention comprise a mixture in all proportions of the three polymers A, B and
C. In
this mixture, the amount by weight of one of the polymers of type A or B or C
relative
to the total weight of the polymers in the mixture can be at least 10% and at
most
80%. Thus, preferably we can have mixtures A/B/C whose proportions by weight
are
10/10/80 or 10/80/10 or 80/10/10 and all intermediate proportions.
According to an embodiment, the compositions according to the invention
comprise a mixture of the three polymers A, B and C in which polymer A is
present in
an amount from 30 to 45 wt.%, polymer B is present in an amount from 1 to 20
wt.%
and polymer C is present in an amount from 30 to 45 wt.%, these percentages
being
expressed relative to the total weight of the polymers.
More particularly, the mixtures of polymers used in the invention as defined
above
represent at least 5%, preferably from 5 to 40%, more preferably 5 to 15 wt.%,
based
on the weight of the final lubricating composition.
According to an embodiment the minimum amount of a polymer relative to the
total weight of the final composition is 1%.
In the field of lubricants all these percentages generally correspond to
polymers
that comprise at least 5% of polymeric active substance, the remainder being
represented by a base oil used as a diluent. Moreover, in certain cases when
the
polymer requires little or no dilution (for example the PA0s), these
percentages can
be up to 100% of polymeric active substance.
CA 02667583 2009-04-24
Consequently, these lubricants adapt very rapidly to the conditions of use
required
in each mechanism.
In order to prepare the lubricating composition according to the invention, a
mixture of at least two polymers of type A, B or C is incorporated, generally
at a
5 temperature between 20 and 100 C and at atmospheric pressure, in at least
one oil of
groups I to V optionally comprising a package of additives and optionally a
pour point
improver.
The polymers of type "A", "B" or "C" according to the present invention can be
incorporated in the composition in the form of separate components, or else
they can
10 be introduced as a component of the package of additives, as an additive
or a diluent.
Thus, the lubricating compositions according to the invention are prepared by
incorporating at least one of the viscosity improving polymers of type A, B,
or C
directly in the composition as a separate additive, independently of the
package of
additives.
15 According to another embodiment, all or part of at least one of the
viscosity
improving polymers of type A, B, or C is incorporated in the lubricant as an
element
of a package of additives.
According to another embodiment all or part of at least one of the viscosity
improving polymers of type A, B, or C is incorporated in the lubricant as a
diluent in
the package of additives.
The compositions according to the invention are used as a single lubricant in
various mechanisms of motor vehicles simultaneously, in particular in
mechanisms
having different shear rates. Thus, the compositions according to the
invention have a
performance that is particularly well suited for good high-temperature
stability in the
engine and the transmission and for cold starting of the hydraulic system.
Examples: The examples given below are for the purpose of illustrating the
invention without limiting its scope.
The mixtures were prepared with stirring at 80 C in 1-litre bottles. The ASTM
D445 standard is applied for the determination of kinematic viscosities. Two
samples
of lubricants were prepared, of grade 40 and 30 respectively according to the
SAE J
300 classification.
Example 1:
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16
A lubricant was prepared containing 50 wt.% of a base oil of group IV having a
viscosity of 2 cSt at 100 C, and 14.25 wt.% of a commercial package of
additives
referenced as supplier 1. This package of additives did not contain any
polymers of
type "A", "B" or "C" according to the present invention, and the diluent was
constituted by base oil.
A mixture consisting of:
31 wt.% of a poly-alpha-olefin of type "A" according to the present invention,
having a PSSI of 6, and
4.75 wt.% of a formulation containing 35% of active substance represented by a
copolymeric ester of type "C" according to the present invention, having a
PSSI of 93
was then added to said lubricant.
The lubricant thus prepared was of grade 40 according to the classification
SAE
J300.
Example 2:
A lubricant was prepared containing 77.5 wt.% of a base oil of group IV with a
viscosity of 4.2 cSt at 100 C, and 14.50 wt.% of a commercial package of
additives
referenced as supplier 2. This package of additives did not contain any
polymers of
type "A", "B" or "C" according to the present invention and the diluent was
constituted by base oil.
A mixture consisting of:
3.5 wt.% of a heavy poly-alpha-olefin of type "A" according to the present
invention, having a PSSI of 35, and
1 wt.% of a formulation containing 63% of active substance represented by a
PMA polymer of type "B" according to the present invention, having a PSSI of
63,
and
3.5 wt.% of a formulation containing 10.8% of active substance represented by
a
hydrogenated styrene-isoprene copolymer of type "C" according to the present
invention, having a PSSI of 90 was then added to said lubricant.
The lubricant thus prepared was of grade 30 according to the SAE J300
classification.
The following table gives the viscosity values in cSt of these two lubricating
compositions:
at 100 C after the KRL-20 hours test according to the CEC-L-45-A-99 standard,
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at 100 C after the Bosch-30 cycles test according to the CEC-L- 14-A-93
standard,
at 40 C after the KRL-3 hours test, according to the CEC-L-45-A-99 standard
with the test duration reduced to 3 hours.
Table I:
Example 1 Example 2
Base oils
Group IV with a viscosity of 2 cSt 50.00
(% of total weight of lubricant)
Group III with a viscosity of 4.2 cSt 77.50
Packages of additives
supplier 1 14.25
supplier 2 14.50
VI improving polymers/ PSSI
Type "A" Spectrasyn 150/ 6 31.00
Type "A" Spectrasyn 1000/ 35 3.50
Type "C" Lubrizol 3702/ 93 4.75
Type "B" Visco 8-400/ 63 1.00
Type "C" ShellVis 261/ 90 3.50
results
Single lubricating composition Grade 40 Grade 30
Viscosity at 40 C after KRL 3H (hydraulics) in cSt 50.00 51.00
Viscosity at 100 C after KRL 20H (gearbox) in cSt 9.80 8.50
Viscosity at 100 C after Bosch 30 cycles (engine) in cSt 12.00 11.20
Spectrasyn 150 is a poly-alpha-olefin (PAO)
Spectrasyn 1000 is a poly-alpha-olefin (PAO)
Lz 3702 is a copolymeric ester
Viscoplex 8-400 is a polymethacrylate
SV 261 is a hydrogenated styrene-butadiene copolymer
The packages of additives from suppliers 1 and 2 are commercial packages of
additives for engine oil diluted in oils of group I to III and not containing
any polymer
of types A, B or C according to the present invention.
These packages make it possible in particular to formulate lubricants for
engines
having performances at level E3 of the ACEA.
