Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LUBRICATING OIL COMPOSITION
The present invention relates to a lubricating oil
composition, in particular to a lubricating oil
composition which is suitable for lubricating internal
combustion engines and which has improved friction
reduction and fuel economy.
Increasingly severe automobile regulations in respect
of emissions and fuel efficiency are placing increasing
demands on both engine manufacturers and lubricant
formulators to provide effective solutions to improve
fuel economy.
Optimising lubricants through the use of high
performance basestocks and novel additives represents a
flexible solution to a growing challenge.
Friction-reducing additives (which are also known as
friction modifiers) are important lubricant components in
reducing fuel consumption and various such additives are
already known in the art.
Friction modifiers can be conveniently divided into
two categories, that is to say, metal-containing friction
modifiers and ashless (organic) friction modifiers.
Organo-molybdenum compounds are amongst the most common
metal-containing friction modifiers. Typical organo-
molybdenum compounds include molybdenum dithiocarbamates
(MoDTC), molybdenum dithiophosphates (MoDTP), molybdenum
amines, molybdenum alcoholates, and molybdenum alcohol-
amides. WO-A-98/26030, WO-A-99/31113, WO-A-99/47629 and
WO-A-99/66013 describe tri-nuclear molybdenum compounds
for use in lubricating oil compositions.
However, the trend towards low-ash lubricating oil
compositions has resulted in an increased drive to
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achieve low friction and improved fuel economy using
ashless friction modifiers.
Ashless (organic) friction modifiers typically
comprise esters of fatty acids and polyhydric alcohols,
fatty acid amides, amines derived from fatty acids and
organic dithiocarbamate or dithiophosphate compounds.
Further improvements in lubricant performance
characteristics have been achieved through the use of
synergistic behaviours of particular combinations of
lubricant additives.
WO-A-99/50377 discloses a lubricating oil composition
which is said to have a significant increase in fuel
economy due to the use therein of tri-nuclear molybdenum
compounds in conjunction with oil soluble
dithiocarbamates.
EP-A-1041135 discloses the use of succinimide
dispersants in conjunction with molybdenum
dialkyldithiocarbamates to give improved friction
reduction in diesel engines.
US-B1-6562765 discloses a lubricating oil composition
which is said to have a synergy between an oxymolybdenum
nitrogen dispersant complex and an oxymolybdenum
dithiocarbamate which leads to unexpectedly low friction
coefficients.
EP-A-1367116, EP-A-0799883, EP-A-0747464,
US-A-3933659 and EP-A-335701 disclose lubricating oil
compositions comprising various combinations of ashless
friction modifiers.
WO-A-92/02602 describes lubricating oil compositions
for internal combustion engines which comprise a blend of
ashless friction modifiers which are said to have a
synergistic effect on fuel economy.
The blend disclosed in WO-A-92/02602 is a combination
of (a) an amine/amide friction modifier prepared by
reacting one or more acids with one or more polyamines
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and (b) an ester/alcohol friction modifier prepared by
reacting one or more acids with one or more polyols.
US-A-5286394 discloses a friction-reducing
lubricating oil composition and a method for reducing the
fuel consumption of an internal combustion engine.
The lubricating oil composition disclosed therein
comprises a major amount of an oil having lubricating
viscosity and a minor amount of a friction-modifying,
polar and surface active organic compound selected from a
long list of compounds including mono- and higher esters
of polyols and aliphatic amides. Glycerol monooleate and
oleamide (i.e. oleylamide) are mentioned as examples of
such compounds.
However, current strategies with regard to friction
reduction for fuel economy oils are not sufficient to
meet ever increasing fuel economy targets set by Original
Equipment Manufacturers (OEMs).
For example, molybdenum friction modifiers typically
outperform ashless friction modifiers in the boundary
regime and there is a challenge to approach similar
levels of friction modification using solely ashless
friction modifiers.
Thus, given the increasing fuel economy demands
placed on engines, there remains a need to further
improve the friction reduction and fuel economy of
internal combustion engines utilising low ash lubricating
oil compositions.
It is therefore desirable to further improve on the
performance of known ashless friction modifiers and known
combinations of ashless friction modifiers, in particular
to further improve on the friction-reducing performance
of polyol ester friction modifiers and ashless friction
modifier combinations of fatty acid amides and polyol
esters (for example, combinations of oleylamide and
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glycerol monooleate) that have been commonly used in the
art.
There has now been surprisingly found in the present
invention a lubricating oil composition comprising
ashless friction modifiers which has good friction
reduction and fuel economy.
Accordingly, the present invention provides a
lubricating oil composition comprising base oil,
oleylamide and one or more ether compounds.
By "ether compound" in the present invention is meant
a saturated or unsaturated hydrocarbon compound
comprising one or more ether linkages and optionally
comprising one or more hydroxyl groups therein, which
compound does not comprise any additional functional
groups.
The choice of ether compounds for use in the present
invention is not limited. However, said ether compounds
are preferably non-cyclic ethers.
Particularly preferred ether compounds that may be
conveniently employed in the present invention are
compounds of formula I,
OR2
I
R10CH2-CH-CHZOR3
(I)
wherein R1, R2 and R3 are each, independently, selected
from hydrogen, alkyl groups having from 10 to 30 carbon
atoms, preferably from 16 to 22 carbon atoms and
unsaturated hydrocarbon groups having from 10 to 30
carbon atoms, preferably from 16 to 22 carbon atoms.
Preferred ether compounds are those in which Rl is an
alkyl or unsaturated hydrocarbon group having from 10 to
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30 carbon atoms, more preferably from 16 to 22 carbon
atoms and R2 and R3 are hydrogen.
Other preferred ether compounds are those in which R1
and R2 are, independently, an alkyl or unsaturated
hydrocarbon group having from 10 to 30 carbon atoms, more
preferably from 16 to 22 carbon atoms and R3 is hydrogen.
Preferred ether compounds also include those in which
R1 and R3 are, an alkyl or unsaturated hydrocarbon group
having from 10 to 30 carbon atoms, more preferably from
16 to 22 carbon atoms and R2 is hydrogen.
Preferred ether compounds also include those in which
R1, R2 and R3 are, each independently selected from an
alkyl or unsaturated hydrocarbon group having from 10 to
30 carbon atoms, more preferably from 16 to 22 carbon
atoms.
In a preferred embodiment of the present invention,
the lubricating oil composition of the present invention
may comprise a mixture of one or more of the afore-
mentioned preferred ether compounds.
Examples of ether compounds that may be conveniently
used in the present invention include glycerin oleyl
monoether, glycerin oleyl diether, glycerin oleyl
triether, glycerin stearyl monoether, glycerin stearyl
diether, glycerin stearyl triether and mixtures thereof.
A preferred ether compound includes that available
under the trade designation "ADEKA FM-618C" from Asahi
Denka Kogyo Co. Ltd.
In a preferred embodiment of the present invention,
the one or more ether compounds are present in an amount
in the range of from 0.1 to 5 wt. %, more preferably in
the range of from 0.5 to 4 wt. % and most preferably in
the range of from 1 to 1.5 wt. % based on the total
weight of the lubricating oil composition.
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In a preferred embodiment of the present invention,
oleylamide is present in an amount in the range of from
0.05 to 0.5 wt. %, more preferably in the range of from
0.1 to 0.4 wt. % and most preferably in the range of from
0.15 to 0.3 wt. %, based on the total weight of the
lubricating oil composition.
In a preferred embodiment, the lubricating oil
composition of the present invention further comprises
one or more nitrile compounds.
Preferred nitrile compounds that may be conveniently
employed in the present invention are saturated and
unsaturated hydrocarbon compounds containing one or more
cyano groups (-C=N), which compounds preferably do not
comprise any additional functional group substituents.
Particularly preferred nitrile compounds that may be
conveniently employed in the present invention are
branched or linear, saturated or unsaturated aliphatic
nitriles.
Nitrile compounds preferably having from 8 to 24
carbon atoms, more preferably from 10 to 22 carbon atoms,
and most preferably from 10 to 18 carbon atoms are
preferred.
Particularly preferred nitrile compounds are
saturated or unsaturated linear aliphatic nitriles having
from 8 to 24 carbon atoms, more preferably from 10 to 22
carbon atoms, and most preferably 10 to 18 carbon atoms.
Examples of nitrile compounds that may be
conveniently used in the present invention include
coconut fatty acid nitriles, oleylnitrile, decanenitrile
and tallow nitriles.
Preferred nitrile compounds that may be conveniently
used in the present invention include that available
under the trade designation "ARNEEL 12" (also known under
the trade designation "ARNEEL C") (coconut fatty acid
nitrile, a mixture of C10, C12, C14 and C16 saturated
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nitriles) from Akzo Nobel, that available under the trade
designation "ARNEEL 0" (oleylnitrile) from Akzo Nobel and
those available under the trade designations "ARNEEL 1OD"
(decanenitrile), "ARNEEL T" (tallow nitriles) and "ARNEEL
M" (c16-22 nitriles) from Akzo Nobel.
In a preferred embodiment of the present invention,
the one or more nitrile compounds are present in an
amount in the range of from 0.1 to 0.8 wt. %, more
preferably in the range of from 0.2 to 0.6 wt. % and most
preferably in the range of from 0.3 to 0.5 wt. % based on
the total weight of the lubricating oil composition.
The total amount of base oil incorporated in the
lubricating oil composition of the present invention is
preferably present in an amount in the range of from 60
to 92 wt. %, more preferably in an amount in the range of
from 75 to 90 wt. % and most preferably in an amount in
the range of from 75 to 88 wt. %, with respect to the
total weight of the lubricating oil composition.
There are no particular limitations regarding the
base oil used in the present invention, and various
conventional known mineral oils and synthetic oils may be
conveniently used.
The base oil used in the present invention may
conveniently comprise mixtures of one or more mineral
oils and/or one or more synthetic oils.
Mineral oils include liquid petroleum oils and
solvent-treated or acid-treated mineral lubricating oil
of the paraffinic, naphthenic, or mixed
paraffinic/naphthenic type which may be further refined
by hydrofinishing processes and/or dewaxing.
Naphthenic base oils have low viscosity index (VI)
(generally 40-80) and a low pour point. Such base oils
are produced from feedstocks rich in naphthenes and low
in wax content and are used mainly for lubricants in
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which colour and colour stability are important, and VI
and oxidation stability are of secondary importance.
Paraffinic base oils have higher VI (generally >95)
and a high pour point. Said base oils are produced from
feedstocks rich in paraffins, and are used for lubricants
in which VI and oxidation stability are important.
Fischer-Tropsch derived base oils may be conveniently
used as the base oil in the lubricating oil composition
of the present invention, for example, the Fischer-
Tropsch derived base oils disclosed in EP-A-776959,
EP-A-668342, WO-A-97/21788, WO-00/15736, WO-00/14188,
WO-00/14187, WO-00/14183, WO-00/14179, WO-00/08115,
WO-99/41332, EP-1029029, WO-01/18156 and WO-01/57166.
Synthetic processes enable molecules to be built from
simpler substances or to have their structures modified
to give the precise properties required.
Synthetic oils include hydrocarbon oils such as
olefin oligomers (PAOs), dibasic acids esters, polyol
esters, and dewaxed waxy raffinate. Synthetic
hydrocarbon base oils sold by the Royal Dutch/Shell Group
of Companies under the designation "XHVI" (trade mark)
may be conveniently used.
Preferably, the base oil constituted from mineral
oils and/or synthetic oils which contain more than 80% wt
of saturates, preferably more than 90 % wt., as measured
according to ASTM D2007.
It is further preferred that the base oil contains
less than 1.0 wt. %, preferably less than 0.1 wt. % of
sulphur, calculated as elemental sulphur and measured
according to ASTM D2622, ASTM D4294, ASTM D4927 or ASTM
D3120.
Preferably, the viscosity index of base fluid is more
than 80, more preferably more than 120, as measured
according to ASTM D2270.
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Preferably, the lubricating oil has a kinematic
viscosity in the range of from 2 to 80 mm2/s at 100 C,
more preferably of from 3 to 70 mm2/s, most preferably of
from 4 to 50 mm2/s.
The total amount of phosphorus in the lubricating oil
composition of the present invention is preferably in the
range of from 0.04 to 0.1 wt. %, more preferably in the
range of from 0.04 to 0.09 wt. % and most preferably in
the range of from 0.045 to 0.09 wt. %, based on total
weight of the lubricating oil composition.
The lubricating oil composition of the present
invention preferably has a sulphated ash content of not
greater than 1.0 wt. %, more preferably not greater than
0.75 wt. % and most preferably not greater than
0.7 wt. %, based on the total weight of the lubricating
oil composition.
The lubricating oil composition of the present
invention preferably has a sulphur content of not greater
than 1.2 wt. %, more preferably not greater than
0.8 wt. % and most preferably not greater than 0.2 wt. o,
based on the total weight of the lubricating oil
composition.
The lubricating oil composition of the present
invention may further comprise additional additives such
as anti-oxidants, anti-wear additives, detergents,
dispersants, friction modifiers, viscosity index
improvers, pour point depressants, corrosion inhibitors,
defoaming agents and seal fix or seal compatibility
agents.
Antioxidants that may be conveniently used include
those selected from the group of aminic antioxidants
and/or phenolic antioxidants.
In a preferred embodiment, said antioxidants are
present in an amount in the range of from 0.1 to
5.0 wt. %, more preferably in an amount in the range of
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from 0.3 to 3.0 wt. %, and most preferably in an amount
of in the range of from 0.5 to 1.5 wt. %, based on the
total weight of the lubricating oil composition.
Examples of aminic antioxidants which may be
conveniently used include alkylated diphenylamines,
phenyl-~-naphthylamines, phenyl-(3-naphthylamines and
alkylated ~-naphthylamines.
Preferred aminic antioxidants include
dialkyldiphenylamines such as p,p'-dioctyl-diphenylamine,
p,p'-di-a-methylbenzyl-diphenylamine and N-p-butylphenyl-
N-p'-octylphenylamine, monoalkyldiphenylamines such as
mono-t-butyldiphenylamine and mono-octyldiphenylamine,
bis(dialkylphenyl)amines such as di-(2,4-
diethylphenyl)amine and di(2-ethyl-4-nonylphenyl)amine,
alkylphenyl-l-naphthylamines such as octylphenyl-l-
naphthylamine and n-t-dodecylphenyl-l-naphthylamine, 1-
naphthylamine, arylnaphthylamines such as phenyl-l-
naphthylamine, phenyl-2-naphthylamine, N-hexylphenyl-2-
naphthylamine and N-octylphenyl-2-naphthylamine,
phenylenediamines such as N,N'-diisopropyl-p-
phenylenediamine and N,N'-diphenyl-p-phenylenediamine,
and phenothiazines such as phenothiazine and 3,7-
dioctylphenothiazine.
Preferred aminic antioxidants include those available
under the following trade designations: "Sonoflex OD-3"
(ex. Seiko Kagaku Co.), "Irganox L-57" (ex. Ciba
Specialty Chemicals Co.) and phenothiazine (ex. Hodogaya
Kagaku Co.).
Examples of phenolic antioxidants which may be
conveniently used include C7-C9 branched alkyl esters of
3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-benzenepropanoic
acid, 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t-
butyl-5-methylphenol, 2,4-di-t-butylphenol, 2,4-dimethyl-
6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-
methoxyphenol, 2,5-di-t-butylhydroquinone, 2,6-di-t-
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butyl-4-alkylphenols such as 2,6-di-t-butylphenol, 2,6-
di-t-butyl-4-methylphenol and 2,6-di-t-butyl-4-
ethylphenol, 2,6-di-t-butyl-4-alkoxyphenols such as 2,6-
di-t-butyl-4-methoxyphenol and 2,6-di-t-butyl-4-
ethoxyphenol, 3,5-di-t-butyl-4-
hydroxybenzylmercaptooctylacetate, alkyl-3-(3,5-di-t-
butyl-4-hydroxyphenyl)propionates such as n-octadecyl-3-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-butyl-3-
(3,5-di-t-butyl-4-hydroxyphenyl)propionate and 2'-
ethylhexyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,
2,6-d-t-butyl-a-dimethylamino-p-cresol, 2,2'-methylene-
bis(4-alkyl-6-t-butylphenol) such as 2,2'-methylenebis(4-
methyl-6-t-butylphenol, and 2,2-methylenebis(4-ethyl-6-t-
butylphenol), bisphenols such as 4,4'-butylidenebis(3-
methyl-6-t-butylphenol, 4,4'-methylenebis(2,6-di-t-
butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 2,2-(di-p-
hydroxyphenyl)propane, 2,2-bis(3,5-di-t-butyl-4-
hydroxyphenyl)propane, 4,4'-cyclohexylidenebis(2,6-t-
butylphenol), hexamethyleneglycol-bis[3-(3,5-di-t-butyl-
4-hydroxyphenyl)propionate], triethyleneglycolbis[3-(3-t-
butyl-4-hydroxy-5-methylphenyl)propionate], 2,2'-thio-
[diethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],
3,9-bis{1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methyl-
phenyl)propionyloxy]ethyl}2,4,8,10-
tetraoxaspiro[5,5]undecane, 4,4'-thiobis(3-methyl-6-t-
butylphenol) and 2,2'-thiobis(4,6-di-t-butylresorcinol),
polyphenols such as tetrakis[methylene-3-(3,5-di-t-butyl-
4-hydroxyphenyl)propionate]methane, 1,1,3-tris(2-methyl-
4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-
tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis-[3,3'-
bis(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol
ester, 2-(3',5'-di-t-butyl-4-hydroxyphenyl)methyl-4-
(2",4"-di-t-butyl-3"-hydroxyphenyl)methyl-6-t-butylphenol
and 2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)-4-
methylphenol, and p-t-butylphenol - formaldehyde
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condensates and p-t-butylphenol - acetaldehyde
condensates.
Preferred phenolic antioxidants include those
available under the following trade designations:
"Irganox L-135" (ex. Ciba Specialty Chemicals Co.),
"Yoshinox SS" (ex. Yoshitomi Seiyaku Co.), "Antage W-400"
(ex. Kawaguchi Kagaku Co.), "Antage W-500" (ex. Kawaguchi
Kagaku Co.), "Antage W-300" (ex. Kawaguchi Kagaku Co.),
"Irganox L109" (ex. Ciba Speciality Chemicals Co.),
"Tominox 917" (ex. Yoshitomi Seiyaku Co.), "Irganox L115"
(ex. Ciba Speciality Chemicals Co.), "Sumilizer GA80"
(ex. Sumitomo Kagaku), "Antage RC" (ex. Kawaguchi Kagaku
Co.), "Irganox L101" (ex. Ciba Speciality Chemicals Co.),
"Yoshinox 930" (ex. Yoshitomi Seiyaku Co.).
The lubricating oil composition of the present
invention may comprise mixtures of one or more phenolic
antioxidants with one or more aminic antioxidants.
In a preferred embodiment, the lubricating oil
composition may comprise a single zinc dithiophosphate or
a combination of two or more zinc dithiophosphates as
anti-wear additives, the or each zinc dithiophosphate
being selected from zinc dialkyl-, diaryl- or alkylaryl-
dithiophosphates.
Zinc dithiophosphate is a well known additive in the
art and may be conveniently represented by general
formula II;
R20 OR9
P S - Zn - S - P (II)
R30 / I I \ OR5
S S
wherein R2 to R5 may be the same or different and are
each a primary alkyl group containing from 1 to 20 carbon
atoms preferably from 3 to 12 carbon atoms, a secondary
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alkyl group containing from 3 to 20 carbon atoms,
preferably from 3 to 12 carbon atoms, an aryl group or an
aryl group substituted with an alkyl group, said alkyl
substituent containing from 1 to 20 carbon atoms
preferably 3 to 18 carbon atoms.
Zinc dithiophosphate compounds in which R2 to R5 are
all different from each other can be used alone or in
admixture with zinc dithiophosphate compounds in which R2
to R5 are all the same.
Preferably, the or each zinc dithiophosphate used in
the present invention is a zinc dialkyl dithiophosphate.
Examples of suitable zinc dithiophosphates which are
commercially available include those available ex.
Lubrizol Corporation under the trade designations "Lz
1097" and "Lz 1395", those available ex. Chevron Oronite
under the trade designations "OLOA 267" and "OLOA 269R",
and that available ex. Afton Chemical under the trade
designation "HITEC 7197"; zinc dithiophosphates such as
those available ex. Lubrizol Corporation under the trade
designations "Lz 677A", "Lz 1095" and "Lz 1371", that
available ex. Chevron Oronite under the trade designation
"OLOA 262" and that available ex. Afton Chemical under
the trade designation "HITEC 7169"; and zinc
dithiophosphates such as those available ex. Lubrizol
Corporation under the trade designations "Lz 1370" and
"Lz 1373" and that available ex. Chevron Oronite under
the trade designation "OLOA 260".
The lubricating oil composition according to the
present invention may generally comprise in the range of
from 0.4 to 1.0 wt. % of zinc dithiophosphate, based on
total weight of the lubricating oil composition.
Additional or alternative anti-wear additives may be
conveniently used in the composition of the present
invention.
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Typical detergents that may be used in the
lubricating oil of the present invention include one or
more salicylate and/or phenate and/or sulphonate
detergents.
However, as metal organic and inorganic base salts
which are used as detergents can contribute to the
sulphated ash content of a lubricating oil composition,
in a preferred embodiment of the present invention, the
amounts of such additives are minimised.
Furthermore, in order to maintain a low sulphur
level, salicylate detergents are preferred.
Thus, in a preferred embodiment, the lubricating oil
composition of the present invention may comprise one or
more salicylate detergents.
In order to maintain the total sulphated ash content
of the lubricating oil composition of the present
invention at a level of preferably not greater than
1.0 wt. %, more preferably at a level of not greater than
0.75 wt. % and most preferably at a level of not greater
than 0.7 wt. %, based on the total weight of the
lubricating oil composition, said detergents are
preferably used in amounts in the range of 0.05 to
12.5 wt. %, more preferably from 1.0 to 9.0 wt. % and
most preferably in the range of from 2.0 to 5.0 wt. o,
based on the total weight of the lubricating oil
composition.
Furthermore, it is preferred that said detergents,
independently, have a TBN (total base number) value in
the range of from 10 to 500 mg.KOH/g, more preferably in
the range of from 30 to 350 mg.KOH/g and most preferably
in the range of from 50 to 300 mg.KOH/g, as measured by
ISO 3771.
The lubricating oil compositions of the present
invention may additionally contain an ash-free dispersant
which is preferably admixed in an amount in the range of
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from 5 to 15 wt. %, based on the total weight of the
lubricating oil composition.
Examples of ash-free dispersants which may be used
include the polyalkenyl succinimides and polyalkenyl
succininic acid esters disclosed in Japanese Patent Nos.
1367796, 1667140, 1302811 and 1743435. Preferred
dispersants include borated succinimides.
Examples of viscosity index improvers which may be
conveniently used in the lubricating oil composition of
the present invention include the styrene-butadiene
copolymers, styrene-isoprene stellate copolymers and the
polymethacrylate copolymer and ethylene-propylene
copolymers. Such viscosity index improvers may be
conveniently employed in an amount in the range of from 1
to 20 wt. %, based on the total weight of the lubricating
oil composition.
Polymethacrylates may be conveniently employed in the
lubricating oil compositions of the present invention as
effective pour point depressants.
Furthermore, compounds such as alkenyl succinic acid
or ester moieties thereof, benzotriazole-based compounds
and thiodiazole-based compounds may be conveniently used
in the lubricating oil composition of the present
invention as corrosion inhibitors.
Compounds such as polysiloxanes, dimethyl
polycyclohexane and polyacrylates may be conveniently
used in the lubricating oil composition of the present
invention as defoaming agents.
Compounds which may be conveniently used in the
lubricating oil composition of the present invention as
seal fix or seal compatibility agents include, for
example, commercially available aromatic esters.
The lubricating oil compositions of the present
invention may be conveniently prepared by admixing
oleylamide, one or more ether compounds and, optionally,
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one or more nitrile compounds and/or further additives
that are usually present in lubricating oil compositions,
for example as herein before described, with a mineral
and/or synthetic base oil.
In another embodiment of the present invention, there
is provided a method of lubricating an internal
combustion engine comprising applying a lubricating oil
composition as hereinbefore described thereto.
The present invention further provides the use of a
combination of oleylamide, one or more ether compounds
and, optionally, one or more nitrile compounds in a
lubricating oil composition in order to improve fuel
economy and/or friction reduction.
The present invention is described below with
reference to the following Examples, which are not
intended to limit the scope of the present invention in
any way.
EXAMPLES
Formulations
Table 1 indicates the formulations that were tested.
The formulations in Table 1 comprised conventional
detergents, dispersants, pour point depressants,
viscosity modifier, antioxidants and zinc dithiophosphate
additives, which were present as additive packages in
diluent oil.
The base oils used in said formulations were mixtures
of polyalphaolefin base oils (PAO-4 available from BP
Amoco under the trade designation "DURASYN 164" and PAO-5
available from Chevron Oronite under the trade
designation "SYNFLUID 5") and ester base oil available
under the trade designation "PRIOLUBE 1976" from Uniqema.
The ether that was used was glycerin oleyl ether
available under the trade designation "ADEKA FM-618C"
from Asahi Denka Kogyo Co. Ltd.
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The oleylamide used was that available under the
trade designation "UNISLIP 1757" from Uniqema.
The glycerol monooleate that was used was that
available under the trade designation "RADIASURF 7149"
from Oleon Chemicals.
The C12 nitrile that was used was that available
under the trade designation "ARNEEL 12" from Akzo Nobel.
All formulations described in Table 1 were SAE 0W20
viscosity grade oils.
Said formulations were manufactured by blending together
the components therein in a single stage blending
procedure at a temperature of 70 C. Heating was
maintained for a minimum of 30 minutes to ensure thorough
mixing, whilst the solution was mixed using a paddle
stirrer.
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Mini-Traction Machine (MTM) Test
Friction measurements were carried out on a Mini-
Traction Machine manufactured by PCS instruments.
The MTM Test was described by R. I. Taylor, E. Nagatomi,
N. R. Horswill, D. M. James in "A screener test for the
fuel economy potential of engine lubricants", presented
at the 13th International Colloquium on Tribology,
January 2002.
Friction coefficients were measured with the Mini-
Traction Machine using the 'ball-on-disc' configuration.
The ball specimen was a polished steel ball bearing,
19.05 mm in diameter. The disc specimen was a polished
bearing steel disc, 46 mm in diameter and 6 mm thick.
The ball specimen was secured concentrically on a
motor driven shaft. The disc specimen was secured
concentrically on another motor driven shaft. The ball
was loaded against the disc to create a point contact
area with minimum spin and skew components. At the point
of contact, a slide to roll ratio of 100% was maintained
by adjusting the surface speed of the ball and disc.
The tests were run at a pressure of 1.25 GPa (load of
71N) or 0.82 GPa (load of 20N) with variable temperatures
and mean surface speeds as detailed in the results
tables.
Results and Discussion
The formulations described in Table 1 were tested
using the afore-mentioned test and the results obtained
thereon are detailed below:
Testing under High Load/High Temperature Conditions
The formulations of Examples 1 and 2 and Comparative
Examples 1 to 3 were tested in the MTM test under high
load (1.25 GPa) and high temperature conditions (105 C
and 125 C) under a variety of speeds (1000, 500, 100 and
50 mm/s).
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Friction coefficients were measured and are described
in Table 2.
TABLE 2
MTM Test Comp. Ex. 1 Ex. 2 Comp. Comp.
Conditions Ex. 1 Ex. 2 Ex. 3
Temp. Speed Friction Coefficient
( C) (mm/s)
125 1000 0.0386 0.0282 0.0272 0.0293 0.0722
125 500 0.0524 0.0365 0.0355 0.0395 0.0909
125 100 0.0811 0.0627 0.0620 0.0654 0.1106
125 50 0.0899 0.0706 0.0695 0.0726 0.1103
105 1000 0.0429 0.0295 0.0289 0.0305 0.0669
105 500 0.0552 0.0362 0.0352 0.0385 0.0842
105 100 0.0832 0.0624 0.0613 0.0648 0.1090
105 50 0.0920 0.0710 0.0700 0.0730 0.1119
Table 3 details the mean % friction reduction for the
formulations of Examples 1 and 2 and Comparative Examples
2 and 3, relative to the mean friction coefficients
measured for the formulation of Comparative Example 1 at
medium speeds (i.e. 1000, 500, 100, 50 mm/s) under the
tested high load conditions.
Positive values in Table 3 indicate improved friction
reduction (i.e. lower friction coefficients) relative to
the mean friction coefficients measured for the
formulation of Comparative Example 1 and negative values
in Table 3 indicate worse friction reduction (i.e.
increased friction coefficients) relative to the mean
friction coefficients measured for the formulation of
Comparative Example 1.
TABLE 3
Ex. 1 Ex. 2 Comp. Ex. 2 Comp. Ex. 3
Temp. ( C) Mean Friction Reduction (0)2
125 + 25.4 + 27.0 + 21.8 - 54.9
105 + 28.4 + 29.8 + 25.5 - 40.3
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2 Relative mean friction coefficients measured for the
formulation of Comparative Example 1.
Table 4 details the mean % friction reduction for the
formulations of Examples 1 and 2 and Comparative Examples
2 and 3, relative to the mean friction coefficients
measured for the formulation of Comparative Example 1 at
high temperatures (i.e. 125 C and 105 C) under the
tested high load conditions.
Positive values in Table 4 indicate improved friction
reduction (i.e. lower friction coefficients) relative to
the mean friction coefficients measured for the
formulation of Comparative Example 1 and negative values
in Table 4 indicate worse friction reduction (i.e.
increased friction coefficients) relative to the mean
friction coefficients measured for the formulation of
Comparative Example 1.
TABLE 4
Ex. 1 Ex. 2 Comp. Ex. 2 Comp. Ex. 3
Speed Mean Friction Reduction (0)3
(mm/s)
1000 + 29.1 + 31.1 + 26.5 - 71.5
500 + 32.4 + 34.2 + 27.4 - 63.0
100 + 23.8 + 24.9 + 20.7 - 33.7
50 + 22.1 + 23.3 + 19.9 - 22.2
3 Relative mean friction coefficients measured for the
formulation of Comparative Example 1.
It is apparent from Tables 3 and 4 that the
oleylamide/ether combinations of Examples 1 and 2 show
synergistic friction reduction.
The improvement in friction reduction of the ether
upon addition of oleylamide ranges from 3 to 7 %
depending upon the conditions used.
The results of Table 4 are represented graphically in
Figure 1. It is apparent from Figure 1 that whilst it
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would be expected from the results of Comparative
Examples 2 and 3 that the use of oleylamide in
conjunction with ether would result in worse friction
reduction than in Comparative Example 2, Examples 1 and 2
surprisingly indicate that not only is there no
deterioration in the friction reduction performance using
such a combination, but also that there is further
improvement in the friction reduction performance by
using such combination.
Testing under Low Load/Low Temperature Conditions
The formulations of Examples 1 and 3 and Comparative
Examples 1 and 4 were tested in the MTM test under low
load (0.82 GPa) and low temperature conditions (105 C,
70 C and 45 C) under a variety of low speeds (500, 100,
50 and 10 mm/s).
Friction coefficients were measured and are described
in Table 5.
TABLE 5
MTM Test Comp. Ex. 1 Ex. 1 Ex. 3 Comp. Ex.
Conditions 4
Temp. Speed Friction Coefficient
( C) (MM/s)
105 500 0.0475 0.0259 0.0264 0.1055
105 100 0.0833 0.0634 0.0622 0.1266
105 50 0.0939 0.0754 0.0734 0.1286
105 10 0.0990 0.0800 0.0777 0.1299
70 500 0.0383 0.0279 0.0272 0.0766
70 100 0.0693 0.0519 0.0492 0.1192
70 50 0.0816 0.0677 0.0645 0.1245
70 10 0.0979 0.0871 0.0824 0.1294
45 500 0.0383 0.0344 0.0333 0.0528
45 100 0.0598 0.0433 0.0415 0.1019
45 50 0.0721 0.0563 0.0533 0.1155
45 10 0.0944 0.0856 0.0806 0.1275
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Table 6 details the mean % friction reduction for the
formulations of Examples 1 and 3 and Comparative Example
4, relative to the mean friction coefficients measured
for the formulation of Comparative Example 1 at low
speeds (i.e. 500, 100, 50, 10 mm/s) under the tested low
load conditions.
Positive values in Table 6 indicate improved friction
reduction (i.e. lower friction coefficients) relative to
the mean friction coefficients measured for the
formulation of Comparative Example 1 and negative values
in Table 6 indicate worse friction reduction (i.e.
increased friction coefficients) relative to the mean
friction coefficients measured for the formulation of
Comparative Example 1.
TABLE 6
Ex. 1 Ex. 3 Comp. Ex. 4
Temp. ( C) Mean Friction Reduction (o)4
105 + 27.1 + 28.3 - 60.6
70 + 20.1 + 23.7 - 64.2
45 + 17.3 + 21.1 - 50.9
4 Relative mean friction coefficients measured for the
formulation of Comparative Example 1.
Table 7 details the mean % friction reduction for the
formulations of Examples 1 and 3 and Comparative Example
4, relative to the mean friction coefficients measured
for the formulation of Comparative Example 1 at low
temperatures (i.e. 105 C, 70 C, 45 C) under the tested
low load conditions.
Positive values in Table 7 indicate improved friction
reduction (i.e. lower friction coefficients) relative to
the mean friction coefficients measured for the
formulation of Comparative Example 1 and negative values
in Table 7 indicate worse friction reduction (i.e.
increased friction coefficients) relative to the mean
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friction coefficients measured for the formulation of
Comparative Example 1.
TABLE 7
Ex. 1 Ex. 3 Comp. Ex.
4
Speed (mm/s) Mean Friction Reduction (0)5
500 + 27.6 + 28.8 - 86.7
100 + 25.5 + 28.3 - 64.8
50 + 19.6 + 23.0 - 49.9
10 + 13.2 + 17.3 - 32.8
5 Relative mean friction coefficients measured for the
formulation of Comparative Example 1.
It is apparent from Tables 6 and 7 that the
oleylamide/ether/nitrile combinations of Example 3 show
synergistic friction reduction under low load conditions.
