Field of the invention
The present invention relates to grease compositions, in particular grease
5 compositions having a reduced environmental impact and exhibiting good extreme
pressure and corrosion properties, in particular with respect to metals or metal alloys.
Technological background of the invention
Recent times have seen the increasing significance of environmental problems
on a worldwide scale and the enforcement of protection of the terrestrial biosphere as
10 a major challenge in all sectors of industry. The field of greases is no exception to the
rule, and the risk of pollution of watercourses and soils that is represented in particular
by disposal into the natural environment of base oils, the main ingredients of these
products, means that today progress is expected in respect of these oils, in particular
in the area of biodegradability, for uses which involve the risk of external leakage of
15 greases. At the same time, increasingly powerful machinery is subject to demands
under ever more severe conditions and in addition to biodegradability, for example,
their lubrication products are required to show significant improvements in
performance in terms of extreme pressure and corrosion properties.
Document US 6,316,392 describes a grease composition having an improved
20 corrosion resistance and comprising at least one base oil, a fatty-acid metal soap and
an extreme-pressure additive that can be chosen from a sulfurized fatty acid ester or
PTFE. However, the compositions described in this document do not include the
specific combination of a fluorine-containing polymer and a sulfurized fatty acid ester.
Moreover, this document gives no indication as to the quantity of active sulphur
25 provided by the sulfurized fatty acid ester.
The present invention relates to a grease composition that can be used in
devices which present a risk of external leakage of grease such as automobiles,
construction machinery or agricultural equipment, while at the same time having a
reduced environmental impact, good performance under extreme pressure and a low
30 corrosiveness to metals or metal alloys.
Surprisingly, the applicant observed that a grease composition having a specific
combination of a sulfurized fatty acid ester, said ester providing a certain quantity of
active sulphur at 150°C according to standard ASTM D1662, and a fluorine-containing
polymer, in a base oil of the polyol ester type, has very good extreme pressure
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properties, is not corrosive in particular to metals or metal alloys, in particular to
copper, while having a reduced environmental impact.
Brief description of the invention
The invention relates to a grease composition comprising at least one base oil
5 of the polyol ester type, at least one fatty-acid metal soap, at least one
fluorine-containing polymer and at least one sulfurized fatty acid ester, the quantity by
mass of active sulphur at 150°C according to standard ASTM D1662 provided by the
sulfurized fatty acid ester with respect to the total mass of grease composition being
greater than or equal to 0.15%.
10 Preferably, the polyol ester is chosen from neopentylglycol esters,
trimethylolethane esters, trimethylolpropane esters, pentaerythritol esters and/or
dipentaerythritol esters, used alone or in a mixture.
Preferably, the composition comprises from 50 to 95% by mass with respect to
the total mass of grease composition of a base oil of the polyol ester type, preferably
15 from 60 to 90%, more preferentially from 70 to 80%.
Preferably, the fluorine-containing polymer is polytetrafluoroethylene.
Preferably, the composition comprises from 1 to 10% by mass of
fluorine-containing polymer with respect to the total mass of grease composition,
preferably from 2 to 8%, more preferentially from 3 to 5%.
20 Preferably, the sulfurized fatty acid ester is a fatty acid triglyceride and/or a
fatty acid methyl ester, used alone or in a mixture.
Preferably, the composition comprises from 0.5 to 5% by mass of sulfurized
fatty acid ester with respect to the total mass of grease composition, preferably from
1 to 4%, more preferentially from 2 to 3%.
25 Preferably, the fatty-acid metal soap is a simple fatty-acid metal soap,
preferably of lithium or calcium.
Preferably, the fatty-acid metal soap is lithium 12-hydroxystearate.
Preferably, the composition comprises from 1 to 20 % by mass with respect to
the total mass of the grease composition of fatty-acid metal soap, preferably from 2 to
30 15%, preferentially from 4 to 12%.
Preferably, the polyol ester, or the mixture of polyol esters, has a kinematic
viscosity at 40°C, measured according to standard ASTM D 445, comprised between
3 and 2000 cSt, preferably between 10 and 1500 cSt, more preferentially between
40 and 500 cSt, even more preferentially between 50 and 200 cSt.
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Preferably, the composition has a consistency according to standard ASTM
D217 comprised between 220 and 430 tenths of a millimetre, preferably between
265 and 295 tenths of a millimetre.
Preferably, the quantity by mass of active sulphur at 150°C according to
5 standard ASTM D1662 provided by the sulfurized fatty acid ester, with respect to the
total mass of grease composition, is greater than or equal to 0.15% by mass, preferably
greater than or equal to 0.18%, more preferentially greater than or equal to 0.20%.
Preferably, the composition has a welding load according to standard
ASTM D2596 greater than 315 kg, preferably greater than or equal to 400 kg.
10 Preferably, the composition has a welding load according to standard
DIN 51350/4 greater than 300 daN, preferably greater than or equal to 320 daN, more
preferentially greater than or equal to 340 daN, even more preferentially greater than
or equal to 360 daN.
Preferably, the composition has a classification of corrosiveness to copper
15 according to standard ASTM D4048 of 1 or 2.
The invention also relates to the use in a grease composition comprising at
least one base oil of the polyol ester type and at least one fatty-acid metal soap of at
least one fluorine-containing polymer and at least one sulfurized fatty acid ester, the
quantity by mass of active sulphur at 150°C according to standard ASTM D1662
20 provided by the sulfurized fatty acid ester being greater than or equal to 0.15%, with
respect to the total mass of grease composition, in order to improve the extremepressure
performance according to standards ASTM D2596 and/or DIN 51350/4 of the
grease composition.
Detailed description
25 Sulfurized fatty acid ester
The grease according to the invention comprises at least one sulfurized fatty
acid ester.
The sulfurized fatty acid esters are obtained by sulphurizing fatty acid esters.
Said fatty acid esters are obtained by reaction between one or more fatty acids and
30 alcohols of all sorts or by transesterification between one or more fatty acid esters and
alcohols of all sorts. By sulfurized fatty acid ester is meant an ester of at least one
sulfurized fatty acid, it being understood that this is usually an ester of a sulfurized
mixture of fatty acids.
The fatty acids that can be used to form the sulfurized fatty acid esters are all
35 fatty acids comprising from 6 to 24 carbon atoms, preferably from 14 to 22 carbon
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atoms, more preferentially from 16 to 20 carbon atoms. Fatty acids comprising
18 carbon atoms are the majority fatty acids, i.e. they are present at a concentration
by mass of at least 50% with respect to the total mass of sulfurized fatty acid ester.
The sulfurized fatty acid esters may be sulfurized fatty acid monoesters,
5 sulfurized fatty acid diesters, sulfurized fatty acid triesters or sulfurized fatty acid
polyesters, used alone or in a mixture.
Preferred sulfurized fatty acid monoesters are C1-C4 alkyl monoesters, such as
methyl monoesters, ethyl monoesters, n-propyl monoesters, i-propyl monoesters,
n-butyl monoesters, s-butyl monoesters, t-butyl monoesters. Preferably, the
10 monoester is a methyl monoester. Preferably the sulfurized fatty acid ester is a
sulfurized fatty acid methyl ester.
As an example of sulfurized fatty acid triesters there may be mentioned
sulfurized fatty acid triglycerides which will be fully or partially esterified and will
therefore, in addition to the triesters, optionally comprise diesters and/or monoesters.
15 As an example of sulfurized fatty acid polyesters, there may be mentioned
sulfurized pentaerythritol fatty acid esters.
An advantage of the invention is to provide a grease composition free from
sulfurized olefins and/or polysulphides. Sulfurized fatty acid esters have a reduced
environmental impact, as these are compounds originating from renewable resources
20 (fatty substances and fatty acids) which contain a significant proportion of renewable
carbon. This is not the case of the sulfurized olefins which are obtained by sulphurizing
olefins, products of hydrocarbon origin and of polysulphides which are also obtained
by sulphurizing hydrocarbon source materials. It is noteworthy to observe that good
extreme-pressure performance was achieved using sulfurized fatty acid esters rather
25 than sulfurized olefins or polysulphides, which are known for having better extremepressure
properties, this being possible in particular due to the additional presence of
a fluorine-containing polymer in the grease composition.
By “active sulphur” is meant within the meaning of the present invention, the
sulphur that a chemical compound is capable of giving up or releasing when this
30 compound is placed under the conditions of standard ASTM D1662. Standard ASTM
D-1662 defines a level of active sulphur of a compound at a given temperature as a
difference expressed as a weighted percentage of sulphur content before and after
reacting a sample of this sulfurized compound with a given quantity of copper for a set
time.
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The quantity of active sulphur at 150°C (standard ASTM D1662) in the grease
composition is one of the parameters that are important for achieving good
performance, in particular under extreme pressure. This quantity of active sulphur at
150°C (ASTM D1662) in the grease composition must not be too low, or it is not
5 possible to achieve satisfactory extreme-pressure behaviour. It must not be too high,
or problems will arise from corrosiveness of the grease, in particular to metals and
metal alloys, in particular to copper; neither will too high a quantity of active sulphur
at 150°C (ASTM D1662) in the absence of the fluorine-containing polymer give good
performance, in particular under extreme pressure.
10 Preferably, the quantity of active sulphur at 150°C according to standard
ASTM D1662 provided by the sulfurized fatty acid ester in the grease composition is
greater than or equal to 0.15% by mass with respect to the total mass of grease
composition, preferably greater than or equal to 0.18%, more preferentially greater
than or equal to 0.20%.
15 Preferably, the quantity of active sulphur at 150°C according to standard
ASTM D1662 provided by the sulfurized fatty acid ester in the grease composition is
less than or equal to 5% by mass with respect to the total mass of grease composition,
preferably less than or equal to 4%, more preferentially less than or equal to 2%, even
more preferentially less than or equal to 1%.
20 Preferably, the quantity of sulphur according to standard ASTM D2622
provided by the sulfurized fatty acid ester in the grease composition is greater than
0.3% by mass with respect to the total mass of grease composition, preferably greater
than or equal to 0.34%.
Preferably, the grease composition comprises from 0.5 to 5% by mass with
25 respect to the total mass of grease composition of sulfurized fatty acid ester,
preferably from 1 to 4%, more preferentially from 2 to 3%.
Preferably, the grease composition according to the invention comprises at
least two different sulfurized fatty acid esters, in order to improve the
extreme-pressure performance, preferentially at least one sulfurized fatty acid methyl
30 ester and at least one sulfurized fatty acid triglyceride. For a given quantity of active
sulphur at 150°C, the combination of two different sulfurized fatty acid esters, in
particular a sulfurized fatty acid methyl ester and a sulfurized fatty acid triglyceride,
makes it possible to improve the extreme-pressure performance because the sulphur
is not released in the same manner. The least hindered ester, such as the sulfurized
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fatty acid methyl ester, will be the quickest to release the active sulphur, then the
most hindered ester, such as the sulfurized fatty acid triglyceride, will take its turn.
The sulfurized fatty acid esters used in the present invention are products that
are commercially available, for example from the suppliers PCAS, King Industries,
5 Dover, Magna, Arkema, Rhein Chemie.
Fluorine-containing polymer
The grease compositions according to the invention comprise at least one
fluorine-containing polymer or fluoropolymer, an essential element of the invention
for achieving good extreme-pressure performance.
10 The fluoropolymers are chosen from polytetrafluoroethylenes or PTFE,
poly(tetrafluoroethylene/hexafluoropropene) or FEP,
poly(tetrafluoroethylene/perfluorinated vinyl ethers) or PFA,
perfluorinated polyethers, poly(chlorotrifluoroethylene) or PCTFE,
poly(vinylidene fluoride) or PVDF, poly(ethylene/tetrafluoroethylene) or ETFE,
15 poly(ethylene/chlorotrifluoroethylene) or ECTFE, poly(vinyl fluoride) or PVF,
poly(vinylidene fluoride/hexafluoropropene),
poly(tetrafluoroethylene/perfluorinated vinyl ether),
poly(tetrafluoroethylene/proprene), fluorosilicones, polyfluorophosphazenes.
Preferably the fluoropolymer is exclusively constituted by carbon atoms and
20 fluorine atoms.
Preferably the fluoropolymer is a polytetrafluoroethylene.
Preferably, the polytetrafluoroethylene has an average particle size comprised
between 0.1 and 100 m, preferably between 0.2 and 50, more preferentially between
0.2 and 10, even more preferentially between 0.2 and 5, even more preferentially
25 between 0.2 and 1, even more preferentially between 0.2 and 0.5.
The grease composition according to the invention comprises from 1 to 10% by
mass of fluorine-containing polymer with respect to the total mass of grease
composition, preferably from 2 to 8%, more preferentially from 3 to 5%. A smaller
quantity of fluoropolymer will not allow good extreme-pressure performance to be
30 achieved, while a larger quantity would have a negative environmental impact.
The fluorine-containing polymers used in the present invention are products
that are commercially available, for example from the suppliers Dupont, Solvay,
Maflon, Xeon, Shamrock.
Base oil of the polyol ester type
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The grease composition according to the invention comprises at least one base
oil of renewable origin based on a polyol ester.
The polyol esters that can be used as base oil are diesters, triesters, tetraesters
or complex esters comprising more than four ester functions.
5 The acids that can be used to form the esters are monocarboxylic acids or
dicarboxylic acids.
Preferably, the monocarboxylic acids have from 3 to 22 carbon atoms, more
preferentially from 4 to 20, even more preferentially from 6 to 18, even more
preferentially from 8 to 16, even more preferentially from 10 to 12.
10 There may be mentioned for example hexanoic acid, octanoic acid,
2-ethylhexanoic acid, isooctanoic acid, nonanoic acid, decanoic acid, isodecanoic acid,
oleic acid, stearic acid. Preferably, saturated acids containing no unsaturations are
used.
Preferably, the dicarboxylic acids have from 3 to 22 carbon atoms, more
15 preferentially from 4 to 20, even more preferentially from 6 to 18, even more
preferentially from 8 to 16, even more preferentially from 10 to 12. There may be
mentioned for example succinic acid, adipic acid, azelaic acid, sebacic acid.
The alcohols that can be used to form the esters are monoalcohols (formation
of diesters with dicarboxylic acids), dialcohols, trialcohols or tetraalcohols. The
20 preferred alcohols are polyols such as neopentylglycol, trimethylolpropane,
pentaerythritol.
In order to obtain an sufficient biodegradability, the grease composition
according to the invention comprises from 50 to 95% by mass with respect to the total
mass of grease composition of polyol ester, preferably from 60 to 90%, more
25 preferentially from 70 to 80%.
These base oils of the ester type are chosen for their negligible environmental
impact in contrast to the base oils originating from petroleum that are conventionally
used. Nevertheless the utilization of such base oils of polyol ester type has a negative
impact on the extreme-pressure properties, since these base oils of polyol ester type
30 likewise have a tendency to migrate to the surface of the lubricated parts and are in
competition with the other additives, hence the utilization of the specific combination
of fluoropolymer and sulfurized fatty acid ester.
The base oil of the polyol ester type or the mixture of base oils of the polyol
ester type has a kinematic viscosity at 40°C comprised between 3 and 2000 cSt
35 (standard ASTM D445), preferably between 10 and 1500 cSt, more preferentially
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between 20 and 1000 cSt, even more preferentially between 40 and 500 cSt, even
more preferentially between 50 and 200 cSt. These viscosity ranges, in particular from
50 to 200 cSt, make it possible to achieve a good compromise between
extreme-pressure performance and biodegradability.
5 The base oils used in the present invention are products that are commercially
available, for example from the suppliers Uniqema, Croda, Oléon, Akzo, Nyco.
Soaps
The grease compositions according to the invention are thickened with fatty-acid
metal soaps, which can be prepared separately, or in situ during the manufacture of
10 the grease (in the latter case, the fatty acid is dissolved in the base oil, then the
appropriate metal hydroxide is added).
These thickening agents are products commonly utilized in the field of greases,
easily available and cost-effective. Greases thickened with fatty-acid metal soaps have
a very good mechanical stability, in comparison, for example, with greases comprising
15 thickening agents based on polyureas, which allows easy use in applications where the
grease is applied in an unconfined space. Moreover, polyureas are prepared from
isocyanate, an extremely toxic compound. It is therefore not desirable to use
thickening agents based on polyureas in order to obtain a grease that is biodegradable,
non toxic and free from products classified under CLP Regulation (EC) No 1272/2008.
20 The grease according to the invention is therefore free from thickening agents based
on polyurea and therefore comprises only thickening agents of the fatty-acid metal
soaps type.
Preferentially, long-chain fatty acids are used, typically comprising from 10 to 28
carbon atoms, saturated or unsaturated, optionally hydroxylated.
25 The long-chain fatty acids (typically comprising from 10 to 28 carbon atoms), are
for example capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic
acid, behenic acid, oleic acid, linoleic acid, erucic acid and their hydroxylated
derivatives. 12-hydroxystearic acid, the best-known derivative of this category, is
preferred. Lithium 12-hydoxystearate is the preferred thickening agent.
30 These long-chain fatty acids generally originate from vegetable oils, for
example palm oil, castor oil, rapeseed oil, sunflower oil, etc. or animal fats (tallow,
whale oil, etc).
Soaps known as simple soaps can be formed by using one or more long-chain
fatty acids. Simple soaps are preferred to the complex soaps, because they are more
35 easily biodegradable and do not bioaccumulate.
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Soaps known as complex soaps can also be formed by using one or more
long-chain fatty acids in combination with one or more carboxylic acids with short
hydrocarbon chains comprising at most 8 carbon atoms.
The saponification agent used to produce the soap can be a metallic compound
5 of lithium, sodium, calcium, aluminium; preferentially lithium and calcium, and
preferably a hydroxide, oxide or a carbonate of these metals.
One or more metallic compounds, whether or not having the same metallic
cation, can be used in the greases according to the invention. It is thus possible to use
lithium soaps in combination with calcium soaps in a smaller proportion.
10 The metal soaps are utilized at contents of the order of 1 to 20 % by mass with
respect to the total mass of the grease composition, preferably from 2 to 15%,
preferentially from 4 to 12%.
Process for preparation of the greases
The greases according to the invention are produced by forming the metal soap
15 in situ or by using a preformed soap.
The process for the preparation of the grease by forming the metal soap in situ is
the following.
One or more long-chain or short-chain fatty acid is dissolved in a fraction of the
base oil or of the mixture of base oil at a temperature comprised between 80°C and
20 90°C. This fraction is generally of the order of 40 % to 60% by mass of the total
quantity of oil contained in the final grease.
Then metallic compounds are added at the same temperature, preferentially of
the metallic oxide, hydroxide or carbonate type.
It is thus possible to add a single type of metal or to combine several metals. The
25 preferred metal of the compositions according to the invention is lithium, optionally
combined, in a smaller proportion, with calcium.
The saponification reaction of the long-chain or short-chain fatty acids with the
metallic compound(s) is left to develop at a temperature between 80°C and 90°C.
The water formed is then evaporated off by heating the mixture at a
30 temperature of approximately 100°C to 200°C.
The grease is then cooled down by the remaining fraction of base oil.
Then, at approximately 80°C, the fluorine-containing polymer and the sulfurized
fatty acid ester and any other additives are incorporated.
Sitrring is then carried out for a sufficient time in order to obtain a grease
35 composition, which is then ground in order to improve its uniformity.
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The process for the preparation of the grease with the preformed metal soap is
identical save that there is no saponification reaction, since the soap is already formed.
These preparation processes are well known to a person skilled in the art.
The consistency of a grease measures its hardness or its fluidity at rest. It is
5 assigned a numerical value by the depth of penetration of a cone of given dimensions
and weight. The grease undergoes prior mixing. The conditions for the measurement
of the consistency of a grease are defined by standard ASTM D 217.
Consistency of the greases
According to their consistency, greases are divided into 9 classes or 9 NLGI
10 (National Lubricating Grease Institute) grades commonly used in the field of greases.
These grades are indicated in the table below.
NLGI grade Consistency according to ASTM D 217 (tenths of a millimetre)
000 445 - 475
00 400 - 430
0 355 - 385
1 310 - 340
2 265 - 295
3 220 - 250
4 175 - 205
5 130 - 160
6 85 - 115
Preferably, the greases according to the invention have a consistency
comprised between 220 and 430 tenths of a millimetre according to standard ASTM
D217, covering grades 00, 0, 1, 2 and 3.
15 Preferably, the greases according to the invention have a consistency
comprised between 265 and 295 tenths of a millimetre according to standard ASTM
D217, to cover grade 2.
Other additives
The grease compositions according to the invention can also contain
20 antioxidant additives, for example antioxidants of the phenolic type, anti-rust
additives, such as for example oxidized waxes or amine phosphates, corrosion inhibitor
additives such as tolyltriazoles or dimercaptothiadiazole derivatives.
Technical performance of the greases
The grease compositions according to the invention have good
25 extreme-pressure performance. In particular, the grease compositions according to the
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invention have a welding load measured according to standard ASTM D2596 greater
than 315 kg, preferably greater than or equal to 400 kg. In particular, the grease
compositions according to the invention have a welding load measured according to
standard DIN 51350/4 greater than 300 daN, preferably greater than or equal to
5 320 daN, more preferentially greater than or equal to 340 daN, even more
preferentially greater than or equal to 360 daN.
The grease compositions according to the invention are also only slightly
corrosive, in particular to metals and metal alloys, and more particularly to copper. In
particular, the grease compositions according to the invention tarnish copper strip only
10 slightly (classification 1 according to standard ASTM D4048) or tarnish copper strips
only moderately (classification 2 according to standard ASTM D4048).
In addition to having good extreme-pressure properties and not being corrosive
to metals and metal alloys and more particularly to copper, the grease compositions
according to the invention have a reduced environmental impact. In particular, the
15 greases according to the invention are biodegradable, do not bio-accumulate, are non
toxic for aquatic mediums and are renewable.
Preferably, the grease compositions according to the invention contain
additives which are not hazardous to the environment and human health.
Preferably, the grease compositions according to the invention are free from
20 organic halogenated compounds, nitrite type compounds, metals or metallic
compounds other than sodium, potassium, magnesium, calcium, lithium and/or
aluminium.
Preferably, the grease compositions according to the invention are not toxic to
the aquatic environment.
25 In particular the grease compositions according to the invention have an
aquatic toxicity to algae, daphnia and fish of at least 1000 mg/l according to standards
OECD 201, 202 and 203.
Similarly, the main constituents of the grease, i.e. those present at more than
5% by mass with respect to the total mass of the grease composition, such as the base
30 oil and the soap, have an aquatic toxicity to algae and daphnia of at least 100 mg/l
according to standards OECD 201 and 202.
Similarly, when a constituent has an aquatic toxicity to algae and daphnia of at
least 100 mg/l according to standards OECD 201 and 202 (category D), said constituent
can be present in the grease at any concentration. The grease compositions according
35 to the invention have a concentration by mass of constituents having an aquatic
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toxicity to algae and daphnia comprised between 10 mg/l and 100 mg/l according to
standards OECD 201 and 202 (category E), less than or equal to 25%. The grease
compositions according to the invention have a concentration by mass of constituents
having an aquatic toxicity to algae and daphnia comprised between 1 mg/l and 10 mg/l
5 according to standards OECD 201 and 202 (category F), less than or equal to 2%,
preferably less than or equal to 1%. This only concerns the constituents of the grease
the concentration by mass in the grease of which is greater than or equal to 0.1%.
The grease compositions according to the invention are biodegradable and do
not bioaccumulate. In particular, the grease compositions according to the invention
10 have a concentration by mass of constituents that are ultimately biodegradable in an
aerobic medium (category A according to standards OECD 301A-F, OECD 306,
OECD 301) greater than 75%, a concentration by mass of constituents that are
intrinsically biodegradable in an aerobic medium (category B according to standards
OECD 302B, OECD 302C) or of non-biodegradable constituents and those that do not
15 bioaccumulate (category C) less than or equal to 25%, and a concentration by mass of
non-biodegradable constituents and those that bioaccumulate (category X) less than
or equal to 0.1%. This only concerns the constituents of the grease the concentration
by mass in the grease of which is greater than or equal to 0.1%.
The grease compositions according to the invention contain at least 45% by
20 mass with respect to the total mass of grease composition of carbon originating from
renewable raw materials.
The invention also relates to a lubrication process using the above-described
grease compositions. The process consists of contacting the parts to be lubricated with
the above-described grease compositions.
25 Examples
Different grease compositions are prepared from:
- lithium 12-hydroxystearate (thickening agent). Its aquatic toxicity to algae and
daphnia is over 100 mg/l according to standards OECD 201 and 202 (category D). Its
biodegradability is equal to 83.8% according to OECD 301B (category A).
30 - polytetrafluoroethylene (PTFE). Its aquatic toxicity to algae and daphnia is over
100 mg/l according to standards OECD 201 and 202 (category D). Its biodegradability is
category C according to standard OECD 301B.
- sulfurized fatty acid methyl ester (sulfurized ester 1), comprising 17% by mass of
sulphur with respect to the total mass of sulfurized ester and 48% by mass of active
35 sulphur at 150°C with respect to the total mass of sulfurized ester. Its aquatic toxicity
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to algae and daphnia is comprised between 10 mg/l and 100 mg/l according to
standards OECD 201 and 202 (category E). Its biodegradability is category C according
to standard OECD 301B. It comprises 95% by mass of renewable carbon with respect to
the total mass of sulfurized ester.
5 - sulfurized fatty acid triglycerides (sulfurized ester 2), comprising 15% by mass of
sulphur with respect to the total mass of sulfurized ester and 33% by mass of active
sulphur at 150°C with respect to the total mass of sulfurized ester. 60% by mass of the
sulfurized ester with respect to the total mass of sulfurized ester has an aquatic
toxicity to algae and daphnia comprised between 10 mg/l and 100 mg/l according to
10 standards OECD 201 and 202 (category E) and 40% by mass of the sulfurized ester has
an aquatic toxicity to algae and daphnia comprised between 1 mg/l and 10 mg/l
according to standards OECD 201 and 202 (category E). Its biodegradability is category
C according to standard OECD 301B. It comprises 95% by mass of renewable carbon
with respect to the total mass of sulfurized ester.
15 - ester of trimethylolpropane and saturated fatty acids (base oil 1). Its kinematic
viscosity at 100°C (ASTM D445) is 4.4 cSt, its kinematic viscosity at 40°C (ASTM D445) is
19.6 cSt. Its aquatic toxicity to algae and daphnia is over 100 mg/l according to
standards OECD 201 and 202 (category D). Its biodegradability is equal to
79% according to standard OECD 301B (category A). It comprises 81% by mass of
20 renewable carbon with respect to the total mass of sulfurized ester.
- ester of trimethylolpropane and saturated fatty acids (base oil 2). Its kinematic
viscosity at 100°C (ASTM D445) is 32.2 cSt and its kinematic viscosity at 40°C (ASTM
D445) is 316 cSt. Its aquatic toxicity to algae and daphnia is over 100 mg/l according to
standards OECD 201 and 202 (category D). Its biodegradability is equal to
25 67% according to standard OECD 301B (category A). It comprises 55% by mass of
renewable carbon with respect to the total mass of sulfurized ester.
- 4,4’-methylene bis 2,6-di-tertio-butylphenol (antioxidant 1),
- Octadecyl 3-(3,5-ditertiobutyl-4-hydroxyphenyl) propanoate (antioxidant 2). Its
aquatic toxicity to algae and daphnia is over 100 mg/l according to standards
30 OECD 201 and 202 (category D). Its biodegradability is category B according to
standard OECD 301B.
- Oxidized hydrocarbon waxes (corrosion inhibitor 1). Their aquatic toxicity to algae
and daphnia is comprised between 10 mg/l and 100 mg/l according to standards
OECD 201 and 202 (category E). Their biodegradability is equal to 55% according to
35 standard OECD 301B (category B).
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- Tolyltriazole (corrosion inhibitor 2). Its aquatic toxicity to algae and daphnia is
comprised between 1 mg/l and 10 mg/l according to standards OECD 201 and 202
(category F). Its biodegradability is equal to 4% according to standard OECD 301B
(category C).
5 in the proportions (% by mass) of the following Table I:
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Table I – Composition by mass of the greases
Control
grease 1
Grease of
the
invention
2
Control
grease 3
Grease of
the
invention
4
Control
grease 5
Base oil 1 (%) 18.83 17.85 18.30 18.30 19.06
Base oil 2 (%) 63.12 60.00 61.55 61.55 63.79
Thickening agent (%) 10.96 10.96 10.96 10.96 10.96
Antioxidant 1 (%) 0.09 0.09 0.09 0.09 0.09
Antioxidant 2 (%) 1.00 1.00 1.00 1.00 1.00
Corrosion inhibitor 1
(%)
1.00 1.00 1.00 1.00 1.00
Corrosion inhibitor 2
(%)
- 0.10 0.1 0.1 0.1
PTFE (%) 5.00 5.00 5.00 5.00 -
Sulfurized ester 1 (%) - - - 2.00 -
Sulfurized ester 2 (%) - 4.00 2.00 - 4.00
Control
grease 6
Grease of
the
invention
7
Base oil 1 (%) 18.17 18.32
Base oil 2 (%) 61.18 61.68
Thickening agent (%) 10.96 10.96
Antioxidant 1 (%) 0.09 0.09
Antioxidant 2 (%) 1.00 1.00
Corrosion inhibitor 1
(%)
1.00 1.00
Corrosion inhibitor 2
(%)
0.10 0.10
PTFE (%) 5.00 5.00
Sulfurized ester 1 (%) 1.85
Sulfurized ester 2 (%) 2.50
The control greases and greases according to the invention have the following
5 biochemical characteristics (Table II):
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Table II – Biochemical characteristics of the greases
Control
grease 1
Grease of
the
invention
2
Control
grease 3
Grease of
the
invention
4
Control
grease 5
Quantity of sulphur (%) - 0.60 0.30 0.34 0.60
Quantity of active sulphur
at 150°C (%)
- 0.198 0.099 0.163 0.198
Aquatic toxicity Category E
(%)
1.0 3.4 2.2 3.0 3.4
Aquatic toxicity Category F
(%)
0 1.7 0.9 0.1 1.7
Biodegradability
Category A (%)
93 89 91 91 94
Biodegradability
Category B + C (%)
7.0 11.1 9.1 9.1 6.1
Renewable carbon (%) 50 51 51 51 54
Control
grease 6
Grease of
the
invention
7
Quantity of active sulphur
at 150°C (%)
0.124 0.15
These grease compositions were subjected to extreme-pressure and corrosiveness
tests (Table III).
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Table III - Extreme-pressure and corrosion performance of the greases
Control
grease 1
Grease of
the
invention
2
Control
grease 3
Grease of
the
invention
4
Control
grease 5
4-ball extreme pressure
Welding load (kg) (1)
160 400 315 400 315
4-ball extreme pressure
Last load before welding
(daN) (2)
140 340 280 320 280
4-ball extreme pressure
Welding load (daN) (2)
160 360 300 340 300
Copper corrosion (3) 1a 1b 1a 2c 1b
Control
grease 6
Grease of
the
invention
7
4-ball extreme pressure
Welding load (kg) (1)
315 315
4-ball extreme pressure
Last load before welding
(daN) (2)
260 300
4-ball extreme pressure
Welding load (daN) (2)
280 320
Copper corrosion (3) 1a 2c
(1) ASTM D2596
(2) DIN 51350/4
(3) 5 ASTM D4048
It is noted that the control grease composition 1 has a very mediocre welding
load of 160 kg (ASTM D2596) or 160 daN (DIN 51350/4). The presence of PTFE in the
grease composition is not sufficient to provide good extreme-pressure properties.
It is noted that the control grease composition 5 has a low welding load of
10 315 kg (ASTM D2596) or 300 daN (DIN 51350/4). The presence of sulfurized fatty acid
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ester alone in the grease composition is not sufficient to ensure good extremepressure
properties.
When 2% sulfurized ester 2 is added, the welding load is slightly improved,
since it is 315 kg (ASTM D2596) or 300 daN (DIN 51350/4) in the control grease
5 composition 3, but still insufficient because the quantity of active sulphur at 150°C is
too low.
The presence of 4% of sulfurized ester 2 and PTFE in the grease composition
according to the invention 2 makes it possible to achieve a welding load of 400 kg
(ASTM D2596) or 360 daN (DIN 51350/4).
10 The combination of 2% sulfurized ester 1 and PTFE in the grease composition
according to the invention 4 thus makes it possible to achieve a welding load of 400 kg
(ASTM D2596) or 340 daN (DIN 51350/4).
The results of the control grease 6 show that the combination of a sulfurized
fatty acid ester with PTFE alone is not sufficient to ensure good extreme-pressure
15 properties, when the quantity of active sulphur at 150°C according to standard ASTM
D1662 provided by the sulfurized fatty acid ester is less than 0.15%.
The grease according to the invention 7 shows that a combination of a
sulfurized fatty acid ester and PTFE in a grease composition, the quantity of active
sulphur at 150°C according to standard ASTM D1662 provided by the sulfurized fatty
20 acid ester being greater than or equal to 0.15%, makes it possible to improve the
extreme-pressure properties.
Moreover, the grease compositions according to the invention are only slightly
corrosive to copper.
These results demonstrate that obtaining high extreme-pressure performance
25 is due to the presence of the fluorine-containing polymer in combination with a
sulfurized fatty acid ester which provides to the grease composition a quantity of
active sulphur at 150°C greater than or equal to 0.15% by mass with respect to the
total mass of grease composition. This extreme-pressure performance goes hand in
hand with a low corrosiveness of the grease and a grease which is biodegradable, does
30 not bioaccumulate, is non-toxic, and originates from renewable raw materials.
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We Claim:
1. Grease composition comprising at least one base oil of the polyol ester type, at
least one fatty-acid metal soap, at least one fluorine-containing polymer and at
5 least one sulfurized fatty acid ester, the quantity by mass of active sulphur at 150°C
according to standard ASTM D1662 provided by the sulfurized fatty acid ester with
respect to the total mass of grease composition being greater than or equal to
0.15%.
2. Composition according to claim 1, in which the polyol ester is chosen from
10 neopentylglycol esters, trimethylolethane esters, trimethylolpropane esters,
pentaerythritol esters and/or dipentaerythritol esters, used alone or in a mixture.
3. Composition according to claim 1 or 2, comprising from 50 to 95% by mass with
respect to the total mass of grease composition of a base oil of the polyol ester
type, preferably from 60 to 90%, more preferentially from 70 to 80%.
15 4. Composition according to claim 1, 2 or 3, in which the fluorine-containing polymer
is polytetrafluoroethylene.
5. Composition according to any one of claims 1 to 4, comprising from 1 to 10% by
mass of fluorine-containing polymer with respect to the total mass of grease
composition, preferably from 2 to 8%, more preferentially from 3 to 5%.
20 6. Composition according to any one of claims 1 to 5, in which the sulfurized fatty
acid ester is a fatty acid triglyceride and/or a fatty acid methyl ester, used alone or
in a mixture.
7. Composition according to any one of claims 1 to 6, comprising from 0.5 to 5% by
mass of sulfurized fatty acid ester with respect to the total mass of grease
25 composition, preferably from 1 to 4%, more preferentially from 2 to 3%.
8. Composition according to any one of claims 1 to 7, in which the fatty-acid metal
soap is a simple fatty-acid metal soap, preferably of lithium or calcium.
9. Composition according to any one of claims 1 to 8, in which the fatty-acid metal
soap is lithium 12-hydroxystearate.
30 10. Composition according to any one of claims 1 to 9, comprising from 1 to 20 % by
mass with respect to the total mass of the grease composition of fatty-acid metal
soap, preferably from 2 to 15%, preferentially from 4 to 12%.
11. Composition according to any one of claims 1 to 10, in which the polyol ester, or
the mixture of polyol esters, has a kinematic viscosity at 40°C, measured according
35 to standard ASTM D 445, comprised between 3 and 2000 cSt, preferably between
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10 and 1500 cSt, more preferentially between 40 and 500 cSt, even more
preferentially between 50 and 200 cSt.
12. Composition according to any one of claims 1 to 11, having a consistency according
to standard ASTM D217 comprised between 220 and 430 tenths of a millimetre,
5 preferably between 265 and 295 tenths of a millimetre.
13. Composition according to any one of claims 1 to 12, comprising a quantity by mass
of active sulphur at 150°C according to standard ASTM D1662 provided by the
sulfurized fatty acid ester with respect to the total mass of grease composition,
greater than or equal to 0.18% by mass, preferably greater than or equal to 0.20%.
10 14. Composition according to any one of claims 1 to 13, having a welding load
according to standard ASTM D2596 greater than 315 kg, preferably greater than or
equal to 400 kg.
15. Composition according to any one of claims 1 to 14, having a welding load
according to standard DIN 51350/4 greater than 300 daN, preferably greater than
15 or equal to 320 daN, more preferentially greater than or equal to 340 daN, even
more preferentially greater than or equal to 360 daN.
16. Composition according to any one of claims 1 to 15, having a classification of
corrosiveness to copper according to standard ASTM D4048 of 1 or 2.
17. Use in a grease composition comprising at least one base oil of the polyol ester
20 type and at least one fatty-acid metal soap, at least one fluorine-containing
polymer and at least one sulfurized fatty acid ester, the quantity by mass of active
sulphur at 150°C according to standard ASTM D1662 provided by the sulfurized
fatty acid ester being greater than or equal to 0.15% with respect to the total mass
of grease composition, in order to improve the extreme-pressure performance
25 according to standards ASTM D2596 and/or DIN 51350/4 of the grease
composition.