U.S. patent application number 15/318733 was filed with the patent office on 2017-09-28 for lubricating composition.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Cheng CHEN, Coleen Anne CHIN, Hong GAO, Brian Lee PAPKE, Mark Clift SOUTHBY.
Application Number | 20170275555 15/318733 |
Document ID | / |
Family ID | 53404578 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170275555 |
Kind Code |
A1 |
SOUTHBY; Mark Clift ; et
al. |
September 28, 2017 |
LUBRICATING COMPOSITION
Abstract
A lubricating composition for use in the crankcase of an engine
comprising (i) a base oil; (ii) one or more organo-molybdenum
compounds at a level sufficient to provide from 100 to 1000 ppmw of
molybdenum; and (iii) from 0.2 wt % to 5.0 wt %, by weight of the
lubricating composition, of one or more organic polymeric friction
reducing additives, wherein the one or more organic polymeric
friction reducing additives has a molecular weight ranging from
1000 to 30000 Daltons and is the reaction product of: a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; c)
optionally at least one backbone moiety capable of linking together
polymeric sub units; and d) optionally a chain terminating group.
The lubricating composition provides improvements in terms of
reduced friction and wear, in addition to improved fuel economy
performance.
Inventors: |
SOUTHBY; Mark Clift;
(Chester, Cheshire, GB) ; GAO; Hong; (Katy,
TX) ; CHEN; Cheng; (Katy, TX) ; CHIN; Coleen
Anne; (Houston, TX) ; PAPKE; Brian Lee; (Sugar
Land, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
53404578 |
Appl. No.: |
15/318733 |
Filed: |
June 17, 2015 |
PCT Filed: |
June 17, 2015 |
PCT NO: |
PCT/EP2015/063640 |
371 Date: |
December 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62014468 |
Jun 19, 2014 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2205/02 20130101;
C10M 2209/084 20130101; C10M 2207/028 20130101; C10M 2227/09
20130101; C10N 2040/25 20130101; C10N 2030/02 20130101; C10M
2219/046 20130101; C10N 2010/12 20130101; C10M 2223/045 20130101;
C10M 129/76 20130101; C10M 2215/082 20130101; C10N 2020/04
20130101; C10M 2209/102 20130101; C10M 2209/11 20130101; C10M
133/08 20130101; C10M 2209/111 20130101; C10M 2215/064 20130101;
C10M 2223/042 20130101; C10M 163/00 20130101; C10M 2207/262
20130101; C10M 2209/112 20130101; C10M 139/00 20130101; C10N
2020/02 20130101; C10N 2030/54 20200501; C10M 2205/026 20130101;
C10M 2205/173 20130101; C10N 2030/06 20130101; C10N 2030/68
20200501; C10M 2207/283 20130101; C10M 2205/04 20130101; C10M
169/044 20130101; C10M 2215/26 20130101; C10M 2215/28 20130101;
C10M 2207/02 20130101; C10M 2207/34 20130101; C10M 2207/026
20130101; C10M 2217/044 20130101; C10M 2219/068 20130101; C10N
2010/12 20130101; C10M 2223/045 20130101; C10N 2010/12 20130101;
C10M 2215/26 20130101; C10N 2010/12 20130101; C10M 2207/02
20130101; C10N 2010/12 20130101; C10M 2215/082 20130101; C10N
2010/12 20130101; C10M 2223/042 20130101; C10N 2010/04 20130101;
C10M 2207/262 20130101; C10N 2010/04 20130101; C10M 2207/028
20130101; C10N 2010/04 20130101; C10M 2219/046 20130101; C10N
2010/04 20130101; C10M 2219/068 20130101; C10N 2010/12 20130101;
C10M 2223/045 20130101; C10N 2010/12 20130101; C10M 2215/26
20130101; C10N 2010/12 20130101; C10M 2207/02 20130101; C10N
2010/12 20130101; C10M 2215/082 20130101; C10N 2010/12 20130101;
C10M 2223/042 20130101; C10N 2010/04 20130101; C10M 2207/262
20130101; C10N 2010/04 20130101; C10M 2207/028 20130101; C10N
2010/04 20130101; C10M 2219/046 20130101; C10N 2010/04
20130101 |
International
Class: |
C10M 139/00 20060101
C10M139/00; C10M 133/08 20060101 C10M133/08; C10M 129/76 20060101
C10M129/76 |
Claims
1. A lubricating composition for use in the crankcase of an engine
comprising (i) a base oil; (ii) one or more organo-molybdenum
compounds at a level sufficient to provide from 100 to 1000 ppmw of
molybdenum; and (iii) from 0.2 wt % to 5.0 wt %, by weight of the
lubricating composition, of one or more organic polymeric friction
reducing additives, wherein the one or more organic polymeric
friction reducing additives has a molecular weight ranging from
1000 to 30000 Daltons and is the reaction product of: a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; c)
optionally at least one backbone moiety capable of linking together
polymeric sub units; and d) optionally a chain terminating
group.
2. A lubricating composition according to claim 1 wherein the one
or more organic polymeric friction reducing additives is the
reaction product of: a) a hydrophobic polymeric sub unit which
comprises a hydrophobic polymer selected from polyolefins,
polyacrylics and polystyrenyls; b) a hydrophilic polymeric sub unit
which comprises a hydrophilic polymer selected from polyethers,
polyesters, polyamides; c) at least one backbone moiety capable of
linking together polymeric sub units; and d) a chain terminating
group.
3. A lubricating composition according to claim 1 wherein the one
or more organic polymeric friction reducing additives is the
reaction product of: a) a hydrophobic polymeric sub unit which
comprises a hydrophobic polymer selected from polyolefins,
polyacrylics and polystyrenyls; b) a hydrophilic polymeric sub unit
which comprises a hydrophilic polymer selected from polyethers,
polyesters, polyamides; and c) at least one backbone moiety capable
of linking together polymeric sub units.
4. A lubricating composition according to claim 1 wherein the one
or more organic polymeric friction reducing additives is the
reaction product of: a) a hydrophobic polymeric sub unit which
comprises a hydrophobic polymer selected from polyolefins,
polyacrylics and polystyrenyls; b) a hydrophilic polymeric sub unit
which comprises a hydrophilic polymer selected from polyethers,
polyesters, polyamides; and d) a chain terminating group.
5. A lubricating composition according to claim 1 wherein the
hydrophobic polymeric sub unit comprises a hydrophobic polymer
which is a polyolefin.
6. A lubricating composition according to claim 1 wherein the
hydrophobic polymeric sub unit comprises polyisobutylene polymer
which has been subjected to maleinisation to form polyisobutylene
succinic anhydride having a molecular weight in the range of 300 to
5000 Daltons.
7. A lubricating composition according to claim 1 wherein the
hydrophilic polymeric sub unit comprises a hydrophilic polymer
which is a polyethylene glycol.
8. A lubricating composition according to claim 1 wherein the
backbone moiety is chosen from a polyol, a polycarboxylic acid and
mixtures thereof.
9. A lubricating composition according to claim 1 wherein the chain
terminating group is any fatty carboxylic acid.
10. A lubricating composition according to claim 1 wherein the
reaction product comprises some block copolymer units formed from
linking together during the reaction of some of the hydrophobic and
hydrophilic polymeric sub units.
11. A lubricating composition according to claim 10 wherein the
number of block copolymer units range from 1 to 20.
12. A lubricating composition according to claim 1 wherein the one
or more organo-molybdenum compounds is selected from molybdenum
dithiocarbamates (MoDTC), molybdenum dithiophosphates (MoDTP),
molybdenum amines, molybdenum alcoholates, and molybdenum
alcohol-amides, and mixtures thereof.
13. A lubricating composition according to claim 12 wherein the one
or more organo-molybdenum compounds is a molybdenum dithiocarbamate
(MoDTC).
14. A lubricating composition according to claim 1 additionally
comprising a hydroxy alkyl amine
15. A lubricating composition according to claim 1 wherein the base
oil is a Fischer-Tropsch derived base oil.
16. (canceled)
17. (canceled)
18. (canceled)
19. A method of lubricating an internal combustion engine
comprising: applying a lubricating composition to a surface in a
crankcase of the engine, wherein the lubricating composition
comprises (i) a base oil; (ii) one or more organo-molybdenum
compounds at a level sufficient to provide from 100 to 1000 ppmw of
molybdenum; and (iii) from 0.2 wt % to 5.0 wt %, by weight of the
lubricating composition, of one or more organic polymeric friction
reducing additives, wherein the one or more organic polymeric
friction reducing additives has a molecular weight ranging from
1000 to 30000 Daltons and is the reaction product of: a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; c)
optionally at least one backbone moiety capable of linking together
polymeric sub units; and d) optionally a chain terminating
group.
20. A method according to claim 19 wherein the one or more organic
polymeric friction reducing additives is the reaction product of:
a) a hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; c) at
least one backbone moiety capable of linking together polymeric sub
units; and d) a chain terminating group.
21. A method according to claim 19 wherein the one or more organic
polymeric friction reducing additives is the reaction product of:
a) a hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; and c) at
least one backbone moiety capable of linking together polymeric sub
units.
22. A method according to claim 19 wherein the one or more organic
polymeric friction reducing additives is the reaction product of:
a) a hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
b) a hydrophilic polymeric sub unit which comprises a hydrophilic
polymer selected from polyethers, polyesters, polyamides; and a
chain terminating group.
Description
[0001] 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 and wear reduction and improved fuel
economy.
[0002] 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.
[0003] Optimising lubricants through the use of high performance
base stocks and novel additives represents a flexible solution to a
growing challenge.
[0004] 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.
[0005] Friction modifiers can be conveniently divided into two
categories, that is to say, metal-containing friction modifiers and
ashless (organic) friction modifiers.
[0006] 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.
[0007] However, the trend towards low-ash lubricating oil
compositions has resulted in an increased drive to achieve low
friction and improved fuel economy using ashless friction
modifiers.
[0008] Ashless (organic) friction modifiers which have been used in
the past typically comprise esters of fatty acids and polyhydric
alcohols, fatty acid amides, amines derived from fatty acids and
organic dithiocarbamate or dithiophosphate compounds.
[0009] 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). While there is a challenge to approach
similar levels of friction modification using solely ashless
friction modifiers, molybdenum friction modifiers typically
outperform ashless friction modifiers in the boundary regime.
[0010] While organo-molybdenum compounds are useful for providing
high levels of friction modification, there are also known
limitations with these compounds. For example, molybdenum-based
friction modifiers can negatively impact seals and the TEOST
cleanliness test.
[0011] 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 lower levels
of molybdenum-based friction modifiers.
[0012] WO2011/107739 discloses an automotive engine oil and/or fuel
comprising a base stock and an organic polymeric friction reducing
additive.
[0013] There has now been surprisingly found by the present
inventors that a lubricating oil composition comprising a
combination of organo-molybdenum compound and an organic polymeric
friction reducing additive has improved friction and wear reduction
and improved fuel economy, while requiring reduced levels of
organo-molybdenum compounds.
SUMMARY OF THE INVENTION
[0014] Accordingly, the present invention provides a lubricating
composition for use in the crankcase of an engine comprising (i) a
base oil; (ii) one or more organo-molybdenum compounds at a level
sufficient to provide from 100 to 1000 ppmw of molybdenum; and
(iii) from 0.2 wt % to 5 wt %, by weight of the lubricating
composition, of one or more organic polymeric friction reducing
additives, wherein the one or more organic polymeric friction
reducing additives has a molecular weight ranging from 1000 to
30000 Daltons and is the reaction product of: [0015] a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
[0016] b) a hydrophilic polymeric sub unit which comprises a
hydrophilic polymer selected from polyethers, polyesters,
polyamides; [0017] c) optionally at least one backbone moiety
capable of linking together polymeric sub units; and [0018] d)
optionally a chain terminating group.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 shows a plot of friction coefficient measurements in
the boundary and mixed regimes as a function of speed for the
compositions set out in Table 2.
[0020] FIG. 2 shows a plot of friction coefficient measurements in
the boundary and mixed regimes as a function of speed for the
compositions set out in Table 4.
DETAILED DESCRIPTION OF THE INVENTION
[0021] An essential component of the lubricating compositions of
the present invention is one or more organo-molybdenum compounds at
a level sufficient to provide from 100 to 1000 ppmw of molybdenum,
preferably at a level sufficient to provide from 100 to 300 ppmw of
molybdenum.
[0022] The organo-molybdenum compound for use herein is preferably
selected from molybdenum dithiocarbamates (MoDTC), molybdenum
dithiophosphates (MoDTP), molybdenum amines, molybdenum
alcoholates, molybdenum alcohol-amides, and mixtures thereof. A
preferred organo-molybdenum compound for use herein is molybdenum
dithiocarbamate (MoDTC). In a preferred embodiment herein the
organo-molybdenum compound contains trinuclear molybdenum (referred
to herein as "moly trimer").
[0023] Another essential component of the lubricating compositions
of the present invention is one or more organic polymeric friction
reducing additives wherein the one or more organic polymeric
friction reducing additives has a molecular weight ranging from
1000 to 30000 Daltons and is the reaction product of: [0024] a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
[0025] b) a hydrophilic polymeric sub unit which comprises a
hydrophilic polymer selected from polyethers, polyesters,
polyamides; [0026] c) optionally at least one backbone moiety
capable of linking together polymeric sub units; and [0027] d)
optionally a chain terminating group.
[0028] The hydrophobic polymeric sub unit preferably comprises a
hydrophobic polymer which is a polyolefin or a polyalphaolefin,
more preferably a polyolefin.
[0029] The polyolefin is preferably derived from a polymer of a
monolefin having from 2 to 6 carbon atoms such as ethylene,
propylene, butene and isobutene, more preferably isobutene, the
said polymer containing a chain of from 15 to 500, preferably 50 to
200 carbon atoms.
[0030] The hydrophilic polymeric sub unit comprises a hydrophilic
polymer selected from a polyether, a polyamide or a polyester.
Examples of polyester include polyethylene terephthalate,
polylactide and polycaprolactone. Examples of polyether include
polyglycerol and polyalkylene glycol. In a particularly preferred
embodiment the hydrophilic polymeric sub unit comprises a
hydrophilic polymer which is a polymer of a water soluble alkylene
glycol. A preferred hydrophilic polymeric sub unit comprises a
hydrophilic polymer which is a polyethylene glycol (PEG),
preferably PEG having a molecular weight of 300 to 5000 Daltons,
more preferably 400 to 1000 Daltons, especially 400 to 800 Daltons.
Alternatively, a mixed poly(ethylene-propylene glycol) or mixed
poly(ethylene-butylene glycol) may be used provided they achieve
the desired water solubility criteria. Exemplary hydrophilic
polymer sub units for use in the present invention include PEG 400,
PEG 600 and PEG 1000.
[0031] Other suitable hydrophilic polymeric sub units may comprise
hydrophilic polymers which are polyethers and polyamides derived
from diols and diamines containing acidic groups, e.g. carboxylic
acid groups, sulphonyl groups (e.g. sulphonyl styrenic groups),
amine groups (e.g. tetraethylene pentamine (TEPA) or polyethylene
imine (PEI)), or hydroxyl groups (e.g. sugar based mono- or
co-polymers).
[0032] The hydrophilic polymeric sub unit may be either linear or
branched.
[0033] During the course of the reaction some of the hydrophobic
and hydrophilic polymeric sub units may link together to form block
copolymer units. Either or both of the hydrophobic and hydrophilic
polymeric sub units may comprise functional groups which enable
them to link with the other sub unit. For example, the hydrophobic
polymeric sub unit may be derivatised so that it has a
diacid/anhydride grouping by reaction with an unsaturated diacid or
anhydride, for examples maleic anhydride. The diacid/anhydride can
react by esterification with hydroxyl terminated hydrophilic
polymeric sub units, for example a polyalkylene glycol. In a
further example, the hydrophobic polymeric sub unit may be
derivatised by an epoxidation reaction with a peracid, for example
perbenzoic or peracetic acid. The epoxide can then react with
hydroxyl and/or acid terminated hydrophilic polymeric sub units. In
a further example, a hydrophilic polymeric sub unit which has a
hydroxyl group may be derivatised by esterification with
unsaturated mono carboxylic acids, for example vinyl acids,
specifically acrylic or methacrylic acid. This derivatised
hydrophilic polymeric sub unit can then react with a polyolefin
hydrophobic polymeric sub unit by free radical
copolymerisation.
[0034] A particularly preferred hydrophobic polymeric sub unit
comprises polyisobutylene polymer which has been subjected to
maleinisation to form polyisobutylene succinic anhydride (PIBSA)
having a molecular weight in the range of 300 to 5000 Daltons,
preferably 500 to 1500 Daltons, especially 800 to 1200 Daltons.
Polyisobutylene succinic anhydrides are commercially available
compounds made by an addition reaction between poly(isobutene)
having a terminal unsaturated group and maleic anhydride.
[0035] Such block copolymer units, if present, may be directly
linked to each other and/or they may be linked together by the at
least one backbone moiety. Preferably they are linked together by
the at least one backbone moiety. The choice of backbone moiety
capable of linking together the block copolymer units is governed
by whether the linking of units is between two hydrophobic
polymeric sub units, between two hydrophilic polymeric sub units or
between a hydrophobic polymeric sub unit and a hydrophilic
polymeric sub unit. Generally polyols and polycarboxylic acids form
suitable backbone moieties. The polyol may be a diol, triol,
tetrol, and/or related dimers or trimers or chain extended polymers
of such compounds. Examples of suitable polyols include glycerol,
neopentyl glycol, trimethylolethane, trimethylolpropane,
trimethylolbutane, pentaerthyritol, dipentaerthyritol,
tripentaerthyritol and sorbitol. In a preferred embodiment, the
polyol is a glycerol. Suitably the at least one backbone moiety is
derived from a polycarboxylic acid, for example a di- or
tricarboxylic acid. Dicarboxylic acids are preferred polycarboxylic
acids, though branched chain dicarboxylic acids may also be
suitable. Particularly suitable are straight chained dicarboxylic
acids having a chain length of between 2 and 10 carbon atoms, for
example oxalic, malonic, succinic, glutaric, adipic, pimelic,
suberic, azelaic or sebacic acid. Unsaturated dicarboxylic acids
such as maleic acid may also be suitable. A particularly preferred
polycarboxylic acid backbone moiety to link units is adipic acid.
Alternative linking backbone moieties are low molecular weight
alkenyl succinic anhydrides (ASA) such as C.sub.18ASA.
[0036] In any of the organic polymeric friction reducing additives
different or same backbone moieties can be used to link together
such block copolymer units. When present the number of block
copolymer units in the organic polymeric friction reducing additive
typically ranges from 1 to 20 units, preferably from 1 to 15, more
preferably from 1 to 10 and especially 1 to 7 units.
[0037] When the product of the reaction ends in a reactive group
(e.g. as with the OH in PEG), it may be desirable or useful in some
circumstances to introduce a chain terminating group to the end of
the product of the reaction. It is, for example, particularly
simple to attach a carboxylic acid to an exposed hydroxyl group on
PEG via an ester linkage. In this respect, any fatty carboxylic
acid would be suitable. Suitable fatty acids include
C.sub.12-C.sub.22 linear saturated, branched saturated, linear
unsaturated and branched unsaturated acids, including, but not
limited to lauric acid, erucic acid, isostearic acid, palmitic
acid, oleic acid, and linoleic acid, preferably palmitic acid,
oleic acid and linoleic acid. A particularly preferred fatty acid
for combination with the surfactant is tall oil fatty acid (TOFA),
a derivative of tall oil, which is primarily oleic acid.
[0038] The organic polymeric friction reducing additive used herein
has a molecular weight of from 1000 to 30000 Daltons, preferably
from 1500 to 25000, more preferably from 2000 to 20000 Daltons.
Generally a composition comprising the organic polymeric friction
reducing additive will comprise a range of polymer chains of
different lengths such that there will be a range of molecular
masses in a particular composition. In such a case it is desirable
that a substantial portion of the organic polymeric friction
reducing additive molecules are within the above mentioned size
ranges.
[0039] The organic polymeric friction reducing additive herein has
a desired acid value of less than 20, preferably less than 15.
[0040] In one embodiment of the invention the organic polymeric
friction reducing additive is the reaction product of: [0041] a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
[0042] b) a hydrophilic polymeric sub unit which comprises a
hydrophilic polymer selected from polyethers, polyesters,
polyamides; and [0043] d) a chain terminating group.
[0044] For such an embodiment the preferred molecular weight range
is 1000 to 3000 Daltons and the desired acid value is less than
15.
[0045] In a separate embodiment of the invention the organic
polymeric friction reducing additive is the reaction product of:
[0046] a) a hydrophobic polymeric sub unit which comprises a
hydrophobic polymer selected from polyolefins, polyacrylics and
polystyrenyls; [0047] b) a hydrophilic polymeric sub unit which
comprises a hydrophilic polymer selected from polyethers,
polyesters, polyamides; and [0048] c) at least one backbone moiety
capable of linking together polymeric sub units.
[0049] For such an embodiment, the preferred molecular weight range
is 3000 to 25000, more preferably 5000 to 20000 Daltons. The
desired acid value is preferably less than 10, more preferably less
than 7.
[0050] In another embodiment, the organic polymeric friction
reducing additive is the reaction product of: [0051] a) a
hydrophobic polymeric sub unit which comprises a hydrophobic
polymer selected from polyolefins, polyacrylics and polystyrenyls;
[0052] b) a hydrophilic polymeric sub unit which comprises a
hydrophilic polymer selected from polyethers, polyesters,
polyamides; [0053] c) at least one backbone moiety capable of
linking together polymeric sub units; and [0054] d) a chain
terminating group.
[0055] For such an embodiment the preferred molecular weight range
is 2000 to 10000, more preferably 2000 to 5000 Daltons. The desired
acid value is preferably less than 15, more preferably less than
10.
[0056] The ingredients of the reactions a), b) and c) when present
and d) when present may be mixed in a single step process or they
may be mixed together in a multi step-process.
[0057] The organic polymeric friction reducing additive described
hereinabove is commercially available from Croda under the trade
names Perfad 3050 and Perfad 3006.
[0058] The organic polymeric friction reducing additive is present
at a level of from 0.2 wt % to 5.0 wt %, preferably at a level of
from 0.3 wt % to 3.0 wt %, more preferably 0.2 wt % to 1.5 wt %, by
weight of the lubricating composition.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] Mineral oils include liquid petroleum oils and
solvent-treated or acid-treated mineral lubricating oils of the
paraffinic, naphthenic, or mixed paraffinic/naphthenic type which
may be further refined by hydrofinishing processes and/or
dewaxing.
[0063] Naphthenic base oils have low viscosity index (VI)
(generally 40-80) and a low pour point. Such base oils are produced
from feed stocks rich in naphthenes and low in wax content and are
used mainly for lubricants in which colour and colour stability are
important, and VI and oxidation stability are of secondary
importance.
[0064] Paraffinic base oils have higher VI (generally >95) and a
high pour point. Said base oils are produced from feed stocks rich
in paraffins, and are used for lubricants in which VI and oxidation
stability are important.
[0065] 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.
[0066] Synthetic processes enable molecules to be built from
simpler substances or to have their structures modified to give the
precise properties required.
[0067] 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.
[0068] Preferably, the base oil comprises 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.
[0069] 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.
[0070] Preferably, the viscosity index of the base oil is more than
80, more preferably more than 120, as measured according to ASTM
D2270.
[0071] Preferably, the lubricating oil composition has a kinematic
viscosity in the range of from 2 to 80 mm.sup.2/s at 100.degree.
C., more preferably of from 3 to 70 mm.sup.2/s, most preferably of
from 4 to 50 mm.sup.2/s.
[0072] The total amount of phosphorus in the lubricating oil
composition of the present invention is preferably in the range of
from 0.04 to 0.12 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
0.08 wt. %, based on total weight of the lubricating oil
composition.
[0073] The lubricating oil composition of the present invention
preferably has a sulphated ash content of not greater than 2.0 wt.
%, more preferably not greater than 1.0 wt. % and most preferably
not greater than 0.8 wt. %, based on the total weight of the
lubricating oil composition.
[0074] 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. %, based on the total weight of the
lubricating oil composition.
[0075] The lubricating oil composition of the present invention may
further comprise additional additives such as anti-oxidants,
anti-wear additives, detergents, dispersants, additional friction
modifiers, viscosity index improvers, pour point depressants,
corrosion inhibitors, defoaming agents and seal fix or seal
compatibility agents.
[0076] A particularly preferred additional additive for use herein
in combination with the organo-molybdenum compound and the organic
polymeric friction reducing additive described hereinabove is a
hydroxy alkyl amine friction modifier, such as that commercially
available from Adeka under the trade name Adeka FM926. When
present, the hydroxy alkyl amine friction modifier is present at a
level of from 0.2 wt % to 3.0 wt %, more preferably at a level of
from 0.3 wt % to 1.0 wt %, by weight of the lubricating
composition.
[0077] Antioxidants that may be conveniently used include those
selected from the group of aminic antioxidants and/or phenolic
antioxidants.
[0078] 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 from 0.3 to 3.0 wt. %, and most
preferably in an amount in the range of from 0.5 to 1.5 wt. %,
based on the total weight of the lubricating oil composition.
[0079] Examples of aminic antioxidants which may be conveniently
used include alkylated diphenylamines,
phenyl-.alpha.-naphthylamines, phenyl-.beta.-naphthylamines and
alkylated .alpha.-naphthylamines.
[0080] Preferred aminic antioxidants include dialkyldiphenylamines
such as p,p'-dioctyl-diphenylamine,
p,p'-di-.alpha.-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-1-naphthylamines such
as octylphenyl-1-naphthylamine and
n-t-dodecylphenyl-1-naphthylamine, 1-naphthylamine,
arylnaphthylamines such as phenyl-1-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.
[0081] 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.).
[0082] Examples of phenolic antioxidants which may be conveniently
used include C.sub.7-C.sub.9 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-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)propionylo-
xy]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''-hydr-
oxyphenyl)methyl-6-t-butylphenol and
2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)-4-methylphenol, and
p-t-butylphenol--formaldehyde condensates and
p-t-butylphenol--acetaldehyde condensates.
[0083] 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.).
[0084] The lubricating oil composition of the present invention may
comprise mixtures of one or more phenolic antioxidants with one or
more aminic antioxidants.
[0085] 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.
[0086] Zinc dithiophosphate is a well known additive in the art and
may be conveniently represented by general formula II;
##STR00001##
wherein R.sup.2 to R.sup.5 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 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.
[0087] Zinc dithiophosphate compounds in which R.sup.2 to R.sup.5
are all different from each other can be used alone or in admixture
with zinc dithiophosphate compounds in which R.sup.2 to R.sup.5 are
all the same.
[0088] Preferably, the or each zinc dithiophosphate used in the
present invention is a zinc dialkyl dithiophosphate.
[0089] 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".
[0090] The lubricating oil composition according to the present
invention may generally comprise in the range of from 0.4 to 1.2
wt. % of zinc dithiophosphate, based on total weight of the
lubricating oil composition.
[0091] Additional or alternative anti-wear additives may be
conveniently used in the composition of the present invention.
[0092] 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.
[0093] 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.
[0094] In order to maintain a low sulphur level, salicylate
detergents can be used.
[0095] Thus, in one embodiment, the lubricating oil composition of
the present invention may comprise one or more salicylate
detergents.
[0096] 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 2.0 wt. %, more preferably at a level
of not greater than 1.0 wt. % and most preferably at a level of not
greater than 0.8 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 20.0 wt. %, more preferably from
1.0 to 10.0 wt. % and most preferably in the range of from 2.0 to
5.0 wt. %, based on the total weight of the lubricating oil
composition.
[0097] Furthermore, it is preferred that said detergents,
independently, have a TBN (total base number) value in the range of
from 10 to 500 mgKOH/g, more preferably in the range of from 30 to
350 mgKOH/g and most preferably in the range of from 50 to 300
mgKOH/g, as measured by ISO 3771.
[0098] 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 from 5 to 15 wt. %, based on
the total weight of the lubricating oil composition.
[0099] 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.
[0100] 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.
[0101] Polymethacrylates may be conveniently employed in the
lubricating oil compositions of the present invention as effective
pour point depressants.
[0102] 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.
[0103] Compounds such as polysiloxanes, dimethyl polycyclohexane
and polyacrylates may be conveniently used in the lubricating oil
composition of the present invention as defoaming agents.
[0104] 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.
[0105] The lubricating compositions of the present invention may be
conveniently prepared using conventional formulation techniques by
admixing base oil with the organo-molybdenum compound and polymeric
friction reducing additive together with and one or more other
optional additives at a temperature of 60.degree. C.
[0106] 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.
[0107] The present invention further provides the use of a
lubricating composition as described herein for reducing
friction.
[0108] The present invention further provides the use of a
lubricating composition as described herein for reducing wear.
[0109] The present invention further provides the use of a
lubricating composition as described herein for improving fuel
economy.
[0110] 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
[0111] A lubricating composition was formulated using conventional
lubricant blending procedures ("Baseline Oil A") having the
composition set out in Table 1 below.
[0112] The amounts of the components are given in wt %, based on
the total weight of the compositions.
TABLE-US-00001 TABLE 1 (Composition of Baseline Oil A) Component Wt
% GTL 4.sup.1 79.50 Additive package.sup.2 13.30 Viscoplex
3-201.sup.3 6.90 PPD.sup.4 0.30 .sup.1A Fischer-Tropsch derived
base oil having a kinematic viscosity at 100.degree. C. (ASTM D445)
of approximately 4 cSt which may be conveniently prepared by the
process described in WO 02/070631. .sup.2Full SAPS additive package
containing polyisobutylene succinimide dispersant, zinc alkyl
dithiophosphate, overbased calcium alkyl salicylate detergent,
borated dispersant and diphenylamine antioxidant. .sup.3Viscosity
modifier commercially available from Evonik. .sup.4Poly alkyl
methacrylate pour point depressant.
[0113] Baseline Oil A had a kV100 (as measured according to ASTM
D445) of 8.02 mm.sup.2/s, a kV40 (as measured according to ASTM
D445) of 35.18 mm.sup.2/s, a CCS at -35.degree. C. (as measured
according to ASTM D5293) of 4330 mPas, and an HTHS (as measured
according to ASTM D4741) of 2.74 mPas.
[0114] Various friction modifiers were added to Baseline Oil A in
the amounts set out in Table 2 below to produce a number of Test
Oils. The friction modifiers added to Baseline Oil A were an
organo-molybdenum compound (molybdenum dithiocarbamate (MoDTC)
containing trinuclear molybdenum, referred to in Table 2 and FIG. 1
as "Moly Trimer"), a polymeric friction reducing additive (Perfad
3006 commercially available from Croda) and glycerol monooleate, a
well known and generally available friction modifier.
[0115] Friction measurements were carried out on the compositions
set out in Table 2 using a Mini-Traction Machine (MTM) manufactured
by PCS Instruments.
[0116] 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 13.sup.th
International Colloquium on Tribology, January 2002.
[0117] Friction coefficients were measured with the Mini-Traction
Machine using the `ball-on-disc` configuration.
[0118] The ball specimen was a polished steel ball bearing, 19.05
mm in diameter. The disc 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.
[0119] The tests were run at a pressure of 1.25 GPa (load of 71N)
at a temperature of 115.degree. C. at a variety of speeds from 2600
mm/s down to 5 mm/s as shown in FIGS. 1 and 2.
[0120] Each oil was tested using a new ball and a new disk for a
total of 20 test scans, and the friction result was taken from the
last three scans.
[0121] Friction coefficients of the relevant Test Oils (as set out
in Table 2) were measured and the results are detailed in Table 2
below. In Table 2, the boundary friction coefficient is the
averaged value at the low speeds from 0.05 m/s to 0.05 m/s, and the
mixed friction coefficient is the averaged value at the higher
speeds from 1.0 m/s to 2.6 m/s.
TABLE-US-00002 TABLE 2 Results Friction coefficient Test Oil:
Boundary Mixed Baseline Oil A 0.107 0.074 99.25 wt % Baseline Oil
0.118 0.067 A + 0.75 wt % Perfad 3006 96.25 wt % Baseline Oil A +
0.112 0.035 3% Moly Trimer + 0.75% glycerol monooleate 99 wt %
Baseline Oil A + 0.055 0.044 0.25% Moly Trimer + 0.75% Perfad
3006
[0122] FIG. 1 shows a plot of friction coefficient measurements in
the boundary and mixed regimes as a function of speed for the
compositions set out in Table 2.
[0123] A further lubricating composition was formulated using
conventional lubricant blending procedures ("Baseline Oil B")
having the composition set out in Table 3 below.
TABLE-US-00003 TABLE 3 (Composition of Baseline Oil B) Component:
Wt % GTL4.sup.1 80.70 SV277.sup.2 7.20 Additive Package.sup.3 12.1
.sup.1A Fischer-Tropsch derived base oil having a kinematic
viscosity at 100.degree. C. (ASTM D445) of approximately 4 cSt
which may be conveniently prepared by the process described in WO
02/070631. .sup.2Hydrogenated styrene-diene copolymer.
.sup.3Additive package containing polyisobutylene succinimide
dispersant, zinc alkyl dithiophosphate, overbased calcium alkyl
phenate and sulphonate detergents, and phenolic antioxidant.
[0124] Baseline Oil B had a kV100 (as measured according to ASTM
D445) of 8.93 mm.sup.2/s, a kV40 (as measured according to ASTM
D445) of 45.20 mm.sup.2/s, a VI of 183, an HTHS at 150.degree. C.
(as measured according to ASTM D4741) of 2.52 cPs, an HTHS at
100.degree. C. (as measured according to ASTM D4741) of 5.55
cPs.
[0125] Various friction modifiers were added to Baseline Oil B in
the amounts set out in Table 4 below to produce a number of Test
Oils. The friction modifiers added to Baseline Oil B were an
organo-molybdenum compound (molybdenum dithiocarbamate (referred to
in Table 4 and FIG. 2 as `holy Trimer`)), a polymeric friction
reducing additive (Perfad 3050 commercially available from Croda)
and Adeka FM926 (a hydroxyalkylamine friction modifier commercially
available from Adeka).
[0126] Friction coefficients of the relevant Test Oils (as set out
in Table 4) were measured using the MTM test method described above
and the results are detailed in Table 4 below. In Table 4, the
boundary friction coefficient is the averaged value at the low
speeds from 0.05 m/s to 0.05 m/s, and the mixed friction
coefficient is the averaged value at the higher speeds from 1.0 m/s
to 2.6 m/s.
TABLE-US-00004 TABLE 4 Results Friction coefficient Test Oil:
Boundary Mixed Baseline Oil B 0.141 0.076 99.5 wt % Baseline Oil B
+ 0.092 0.039 0.5 wt % Perfad 3050 99.5 wt % Baseline Oil B + 0.094
0.034 0.5 wt % Adeka FM926 99.45 wt % Baseline Oil B + 0.048 0.040
0.55 wt % Moly Trimer wt % Baseline Oil A + 1% 0.048 0.033 Perfad
3050 + 0.1 wt % Adeka FM926 + 0.36 wt % Moly Trimer
[0127] FIG. 2 shows a plot of friction coefficient measurements in
the boundary and mixed regimes as a function of speed for the
compositions set out in Table 4.
Discussion
[0128] Lubrication regimes fall into four main categories: (1)
Hydrodynamic, where the surfaces are completely separated by a
fluid film, (2) Elastohydrodynamic, where the surfaces are
separated by a very thin fluid film (3) Mixed, where the surfaces
are partially separated with some asperity contact and (4)
Boundary, where the surfaces are mostly in contact, even though a
fluid film is present. The mixed and boundary regimes rely on
chemical antiwear additives and/or friction modifiers, and the
like, to reduce wear and friction.
[0129] Molybdenum containing friction modifiers are generally
expected to perform well in reducing boundary friction and organic
friction modifiers are thought to be more effective under mixed
conditions.
[0130] As can be seen from Table 2, adding 0.75% polymeric organic
friction modifier alone to Baseline Oil A reduces the friction in
the mixed regime, but appears to increase boundary friction.
[0131] When 170 ppm Mo (3 wt % MoDTC) is added to Baseline Oil A
with 0.75% of a common organic friction modifier, GMO, we see a
slight reduction in boundary friction and significant reduction in
mixed friction.
[0132] When only 140 ppm Mo (0.25 wt % MoDTC) is added with 0.75%
polymeric organic friction modifier, surprisingly, we see a
dramatic reduction in boundary friction and a further reduction in
mixed friction. This appears to be a truly synergistic effect and
could not have been predicted from the other results in Table
2.
[0133] The polymeric organic friction modifier appears to increase
boundary friction alone, yet enables very low boundary friction in
combination with the molybdenum containing friction modifier, which
is very much lower than the molybdenum containing friction modifier
in combination with a conventional organic friction modifier,
GMO.
[0134] Adding 0.5% of an alternative polymeric organic friction
modifier (Perfad 3050) to Baseline Oil B significantly reduces
boundary and mixed friction.
[0135] It appears the hydroxy alkyl amine friction modifier (Adeka
FM926) is more effective in the mixed regime, but a little less
effective at reducing boundary friction.
[0136] When 300 ppm Mo (0.55 wt % molybdenum dithiocarbonate
containing trinuclear molybdenum (identified in Tables 2 and 4, and
in FIGS. 1 and 2, as `Moly trimer`)) is added to Baseline Oil B we
see a very large drop in both boundary and mixed friction, though
mixed friction appears to be marginally higher than that delivered
by the organic friction modifiers.
[0137] When a combination of 200 ppm Mo (0.36 wt % Moly trimer) is
added to Baseline Oil B, in combination with 1% of Perfad 3050 and
0.1% the hydroxy alkyl amine (Adeka FM925) friction modifier we see
very low friction in both boundary and mixed regime. Surprisingly,
the boundary friction is lower using only 200 ppm Mo in this
combination, when compared with that measured with 300 ppm Mo
alone.
* * * * *