U.S. patent application number 16/389220 was filed with the patent office on 2019-11-14 for method for improving engine fuel efficiency.
The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Douglas E. DECKMAN, Mark P. HAGEMEISTER, Nicole WALLACE.
Application Number | 20190345407 16/389220 |
Document ID | / |
Family ID | 66429628 |
Filed Date | 2019-11-14 |
United States Patent
Application |
20190345407 |
Kind Code |
A1 |
DECKMAN; Douglas E. ; et
al. |
November 14, 2019 |
METHOD FOR IMPROVING ENGINE FUEL EFFICIENCY
Abstract
A method for improving fuel efficiency while maintaining or
improving deposit control, in an engine lubricated with a
lubricating oil. The lubricating engine oil has a composition
including from 20 to 85 wt % of a first lubricating oil base stock
selected from the group consisting of a Group I base stock, a Group
II base stock, a Group III base stock, a Group IV base stock, and
combinations thereof; from 5 to 55 wt % of a second lubricating oil
base stock comprising at least one ester based Group V base stock;
from 5 to 20 wt % of at least one viscosity modifier, and one or
more other lubricating oil additives. The lubricating engine oils
are useful in internal combustion engines including direct
injection, gasoline and diesel engines.
Inventors: |
DECKMAN; Douglas E.;
(Easton, PA) ; WALLACE; Nicole; (Coatesville,
PA) ; HAGEMEISTER; Mark P.; (Mullica Hill,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company |
Annandale |
NJ |
US |
|
|
Family ID: |
66429628 |
Appl. No.: |
16/389220 |
Filed: |
April 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62670099 |
May 11, 2018 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2040/255 20200501;
C10M 2207/2805 20130101; C10N 2030/04 20130101; C10M 2203/1025
20130101; C10N 2030/02 20130101; C10M 169/041 20130101; C10M
2205/04 20130101; C10M 2209/084 20130101; C10M 143/12 20130101;
C10M 2205/06 20130101; C10N 2030/54 20200501; C10M 2205/0285
20130101; C10M 2207/2835 20130101; C10M 2205/173 20130101; C10N
2040/252 20200501; C10M 2205/022 20130101; C10N 2020/073 20200501;
C10M 145/14 20130101; C10M 2205/022 20130101; C10M 2205/024
20130101; C10M 2205/04 20130101; C10M 2205/06 20130101; C10M
2203/1025 20130101; C10N 2020/02 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 143/12 20060101 C10M143/12; C10M 145/14 20060101
C10M145/14 |
Claims
1. A method for improving fuel efficiency while maintaining or
improving deposit control, in an engine lubricated with a
lubricating oil by using as the lubricating engine oil a formulated
oil, said formulated oil having a composition comprising: from 20
to 85 wt % of a first lubricating oil base stock selected from the
group consisting of a Group I base stock, a Group II base stock, a
Group III base stock, a Group IV base stock, and combinations
thereof; from 5 to 55 wt % of a second lubricating oil base stock
comprising at least one ester based Group V base stock; from 5 to
20 wt % of at least one viscosity modifier, and wherein the
remainder of the lubricating engine oil includes one or more other
lubricating oil additives; wherein fuel efficiency properties are
improved (kinematic viscosity at 25 deg. C. of less than or equal
to 125 cSt) and deposit control is maintained or improved (TEOST
33C total deposits less than or equal to 60 mg) as compared to fuel
efficiency properties and deposit control achieved using a
lubricating engine oil not containing the at least one ester based
Group V base stock and the at least one viscosity modifier.
2. The method of claim 1, wherein the at least one viscosity
modifier comprises linear or star-shaped polymers and copolymers of
methacrylate, butadiene, olefins, alkylated styrenes or
combinations thereof.
3. The method of claim 1, wherein the at least one viscosity
modifier is selected from the group consisting of polyisobutylene,
polymethacrylate, polyisoprene, copolymers of ethylene and
propylene, hydrogenated block copolymers of styrene and isoprene,
styrene-butadiene based polymers, star polyisoprene polymers, star
polyisoprene-styrene copolymers and combinations thereof.
4. The method of claim 3, wherein the at least one viscosity
modifier is a styrene isoprene copolymer having a molecular weight
of from 50,000 to 200,000.
5. The method of claim 1, wherein the at least one ester based
Group V base stock comprises an ester of trimethylol propane,
trimethylol butane, trimethylol ethane, pentaerythritol or
dipentaerythritol with one or more monocarboxylic acids containing
from 5 to 20 carbon atoms.
6. The method of claim 1, wherein the at least one ester based
Group V base stock is selected from the group consisting of a
C8/C10/C12/C14/C16/C18 Estolide ester, a C11/C13/C15/C17 Estolide
ester, a C8/C10 trimethylolpropane (TMP) ester, a C6/C7/C8/C10 TMP
ester, a C5/C6/C7/C8/C9/C10 TMP ester, a C8/C10/C12/C14/C16/C18/C20
TMP ester, a C7/C8/C10 TMP ester, a C7/C9/C11/C13/C15 TMP ester, a
C6/C7/C9 TMP ester, a C6/C7/C9 TMP ester, a C4/C5/C6/C7/C8/C9 TMP
ester, a C15/C17 propylene glycol diester, a C16/C18 propylene
glycol diester and combinations thereof.
7. The method of claim 6, where the at least one ester based Group
V base stock comprises from 25 to 55 wt % of the lubricating engine
oil.
8. The method of claim 1, wherein the at least one ester based
Group V base stock comprises a monoester, a di-ester, a polyol
ester, a complex ester or mixtures thereof derived from a renewable
biological material.
9. The method of claim 8, wherein the renewable biological material
is derived from coconut oil, palm oil, rapeseed oil, soy oil,
vegetable oil, or sunflower oil.
10. The method of claim 1, wherein the one or more other
lubricating oil additives are selected from the group consisting of
an anti-wear additive, antioxidant, detergents, dispersant, pour
point depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, anti-rust
additive, and friction modifier.
11. The method of claim 1, wherein the lubricating engine oil has a
kinematic viscosity at 25 deg. C. of less than or equal to 110
cSt.
12. The method of claim 1, wherein the lubricating engine oil has
TEOST 33C total deposits less than or equal to 50 mg.
13. The method of claim 1, wherein the lubricating engine oil has a
kinematic viscosity at 100 deg. C. ranging from 8 to 15 cSt.
14. The method of claim 1, wherein the first lubricating oil base
stock is a mixture of a Group III base stock and a Group IV base
stock.
15. The method of claim 14, wherein the Group III base stock is a
gas to liquids (GTL) base stock and the Group IV base stock is a
polyalphaolefin (PAO) base stock.
16. The method of claim 15, wherein the GTL ranges from 20 to 75 wt
% of the lubricating engine oil and the PAO ranges from 2 to 10 wt
% of the lubricating engine oil.
17. The method of claim 1, wherein the high temperature high shear
(HTHS) viscosity at 150.degree. C. of the lubricating engine oil
ranges from 1.5 to 4.5 cP and wherein the lubricating engine oil is
an SAE viscosity grade selected from the group consisting of 0W-30,
5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12, 5W-12, 0W-8, and
5W-8.
18. A lubricating engine oil having a composition comprising: from
20 to 85 wt % of a first lubricating oil base stock selected from
the group consisting of a Group I base stock, a Group II base
stock, a Group III base stock, a Group IV base stock, and
combinations thereof; from 5 to 55 wt % of a second lubricating oil
base stock comprising at least one ester based Group V base stock;
from 5 to 20 wt % of at least one viscosity modifier, and wherein
the remainder of the lubricating engine oil includes one or more
other lubricating oil additives; wherein fuel efficiency properties
are improved (kinematic viscosity at 25 deg. C. of less than or
equal to 125 cSt) and deposit control is maintained or improved
(TEOST 33C total deposits less than or equal to 60 mg) as compared
to fuel efficiency properties and deposit control achieved using a
lubricating engine oil not containing the at least one ester based
Group V base stock and the at least one viscosity modifier.
19. The lubricating engine oil of claim 18, wherein the at least
one viscosity modifier comprises linear or star-shaped polymers and
copolymers of methacrylate, butadiene, olefins, alkylated styrenes
or combinations thereof.
20. The lubricating engine oil of claim 18, wherein the at least
one viscosity modifier is selected from the group consisting of
polyisobutylene, polymethacrylate, polyisoprene, copolymers of
ethylene and propylene, hydrogenated block copolymers of styrene
and isoprene, styrene-butadiene based polymers, star polyisoprene
polymers, star polyisoprene-styrene copolymers and combinations
thereof.
21. The lubricating engine oil of claim 20, wherein the at least
one viscosity modifier is a styrene isoprene copolymer having a
molecular weight of from 50,000 to 200,000.
22. The lubricating engine oil of claim 18, wherein the at least
one ester based Group V base stock comprises an ester of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol or dipentaerythritol with one or more
monocarboxylic acids containing from 5 to 20 carbon atoms.
23. The lubricating engine oil of claim 18, wherein the at least
one ester based Group V base stock is selected from the group
consisting of a C8/C10/C12/C14/C16/C18 Estolide ester, a
C11/C13/C15/C17 Estolide ester, a C8/C10 trimethylolpropane (TMP)
ester, a C6/C7/C8/C10 TMP ester, a C5/C6/C7/C8/C9/C10 TMP ester, a
C8/C10/C12/C14/C16/C18/C20 TMP ester, a C7/C8/C10 TMP ester, a
C7/C9/C11/C13/C15 TMP ester, a C6/C7/C9 TMP ester, a C6/C7/C9 TMP
ester, a C4/C5/C6/C7/C8/C9 TMP ester, a C15/C17 propylene glycol
diester, a C16/C18 propylene glycol diester and combinations
thereof.
24. The lubricating engine oil of claim 23, where the at least one
ester based Group V base stock comprises from 25 to 55 wt % of the
lubricating engine oil.
25. The lubricating engine oil of claim 18, wherein the at least
one ester based Group V base stock comprises a monoester, a
di-ester, a polyol ester, a complex ester or mixtures thereof
derived from a renewable biological material.
26. The lubricating engine oil of claim 25, wherein the renewable
biological material is derived from coconut oil, palm oil, rapeseed
oil, soy oil, vegetable oil, or sunflower oil.
27. The lubricating engine oil of claim 18, wherein the one or more
other lubricating oil additives are selected from the group
consisting of an anti-wear additive, antioxidant, detergents,
dispersant, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, and friction modifier.
28. The lubricating engine oil of claim 18, wherein the lubricating
engine oil has a kinematic viscosity at 25 deg. C. of less than or
equal to 110 cSt.
29. The lubricating engine oil of claim 18, wherein the lubricating
engine oil has TEOST 33C total deposits less than or equal to 50
mg.
30. The lubricating engine oil of claim 18, wherein the lubricating
engine oil has a kinematic viscosity at 100 deg. C. ranging from 8
to 15 cSt.
31. The lubricating engine oil of claim 18, wherein the first
lubricating oil base stock is a mixture of a Group III base stock
and a Group IV base stock.
32. The lubricating engine oil of claim 31, wherein the Group III
base stock is a gas to liquids (GTL) base stock and the Group IV
base stock is a polyalphaolefin (PAO) base stock.
33. The lubricating engine oil of claim 32, wherein the GTL ranges
from 20 to 75 wt % of the lubricating engine oil and the PAO ranges
from 2 to 10 wt % of the lubricating engine oil.
34. The lubricating engine oil of claim 18, wherein the high
temperature high shear (HTHS) viscosity at 150.degree. C. of the
lubricating engine oil ranges from 1.5 to 4.5 cP.
35. The lubricating engine oil of claim 34, wherein the lubricating
engine oil is an SAE viscosity grade selected from the group
consisting of 0W-30, 5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12,
5W-12, 0W-8, and 5W-8.
36. The lubricating engine oil of claim 18, wherein the lubricating
engine oil is a passenger vehicle engine oil (PVEO).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/670,099, filed on May 11, 2018 the entire
contents of which are incorporated herein by reference.
FIELD
[0002] This disclosure relates to improving fuel efficiency while
maintaining or improving deposit control, in an engine lubricated
with a lubricating oil by including at least one ester based Group
V base stock and at least one viscosity modifier in the lubricating
oil.
BACKGROUND
[0003] Fuel efficiency requirements for passenger vehicles are
becoming increasingly more stringent. New legislation in the United
States and European Union within the past few years has set fuel
economy and emissions targets not readily achievable with today's
vehicle and lubricant technology.
[0004] The emission test cycle currently used to certify emission
performance of new vehicles in Europe is the New European Drive
Cycle (NEDC), which consists of measuring the CO.sub.2 emissions or
fuel consumption of a vehicle. In the NEDC, a vehicle is tested on
a chassis dynamometer. The testing begins at 20-30.degree. C. The
vehicle must achieve a specific speed versus time profile, which
simulates urban driving and extra-urban driving. The entire testing
cycle lasts for 1180 seconds. The NEDC drive cycle in the future
will be replaced by the Worldwide Harmonized Light Vehicles Test
Procedure (WLTP). Like the NEDC procedure, in the WLTP test, the
vehicle begins at 20-30.degree. C. The WLTP speed versus time
profile is more dynamic then the NEDC cycle and the test last for
30 minutes. As both of these fuel economy/emission tests begin at
20-30.degree. C., having a lubricant with a lower viscosity in this
temperature range is desirable to reduce emissions and improve fuel
economy.
[0005] To address these increasing standards, automotive original
equipment manufacturers are demanding better fuel economy as a
lubricant-related performance characteristic, while maintaining
deposit control and oxidative stability requirements. One well
known way to increase fuel economy is to decrease the viscosity of
the lubricating oil. However, this approach is now reaching the
limits of current equipment capabilities and specifications. At a
given viscosity, it is well known that adding organic or organic
metallic friction modifiers reduces the surface friction of the
lubricating oil and allows for better fuel economy. However these
additives often bring with them detrimental effects such as
increased deposit formation, seals impacts, or they out-compete the
anti-wear components for limited surface sites, thereby not
allowing the formation of an anti-wear film, causing increased
wear.
[0006] Contemporary lubricants such as engine oils use mixtures of
additives such as dispersants, detergents, inhibitors, viscosity
index improvers and the like to provide engine cleanliness and
durability under a wide range of performance conditions of
temperature, pressure, and lubricant service life.
[0007] Lubricant-related performance characteristics such as high
temperature deposit control and fuel economy are extremely
advantageous attributes as measured by a variety of bench and
engine tests. As indicated above, it is known that adding organic
friction modifiers to a lubricant formulation imparts frictional
benefits at low temperatures, consequently improving the lubricant
fuel economy performance. At high temperatures, however, adding
increased levels of organic friction modifier can invite high
temperature performance issues. For example, engine deposits are
undesirable consequences of high levels of friction modifier in an
engine oil formulation at high temperature engine operation.
[0008] A major challenge in engine oil formulation is
simultaneously achieving high temperature deposit control while
also achieving improved fuel economy.
[0009] Despite the advances in lubricant oil formulation
technology, there exists a need for an engine oil lubricant that
effectively improves fuel economy while maintaining or improving
deposit control.
SUMMARY
[0010] This disclosure relates in part to a method for improving
fuel efficiency, while maintaining or improving deposit control, in
an engine lubricated with a lubricating oil by including at least
one ester based Group V base stock and at least one viscosity
modifier in the lubricating oil. The lubricating oils of this
disclosure are useful in internal combustion engines including
direct injection, gasoline and diesel engines.
[0011] This disclosure also relates in part to a method for
improving fuel efficiency while maintaining or improving deposit
control, in an engine lubricated with a lubricating oil by using as
the lubricating oil a formulated oil. The formulated oil has a
composition comprising from 20 to 85 wt % of a first lubricating
oil base stock selected from the group consisting of a Group I base
stock, a Group II base stock, a Group III base stock, a Group IV
base stock, and combinations thereof; from 5 to 55 wt % of a second
lubricating oil base stock comprising at least one ester based
Group V base stock; from 5 to 20 wt % of at least one viscosity
modifier, and wherein the remainder of the lubricating engine oil
includes one or more other lubricating oil additives. The fuel
efficiency properties are improved (kinematic viscosity at 25 deg.
C. of less than or equal to 125 cSt) and deposit control is
maintained or improved (TEOST 33C total deposits less than or equal
to 60 mg) as compared to fuel efficiency properties and deposit
control achieved using a lubricating engine oil not containing the
at least one ester based Group V base stock and the at least one
viscosity modifier.
[0012] This disclosure further relates in part to a lubricating
engine oil having a composition comprising from 20 to 85 wt % of a
first lubricating oil base stock selected from the group consisting
of a Group I base stock, a Group II base stock, a Group III base
stock, a Group IV base stock, and combinations thereof; from 5 to
55 wt % of a second lubricating oil base stock comprising at least
one ester based Group V base stock; from 5 to 20 wt % of at least
one viscosity modifier, and wherein the remainder of the
lubricating engine oil includes one or more other lubricating oil
additives. The fuel efficiency properties are improved (kinematic
viscosity at 25 deg. C. of less than or equal to 125 cSt) and
deposit control is maintained or improved (TEOST 33C total deposits
less than or equal to 60 mg) as compared to fuel efficiency
properties and deposit control achieved using a lubricating engine
oil not containing the at least one ester based Group V base stock
and the at least one viscosity modifier.
[0013] It has been surprisingly found that, in accordance with this
disclosure, improvements in fuel economy are obtained without
sacrificing engine cleanliness (e.g., while maintaining or
improving deposit control) in an engine lubricated with a
lubricating oil, by including at least one ester based Group V base
stock and at least one viscosity modifier in the lubricating
oil.
[0014] Other objects and advantages of the present disclosure will
become apparent from the detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 shows the various base stocks and the properties of
the base stocks used in accordance with the embodiments of this
disclosure.
[0016] FIG. 2 shows inventive and comparative formulations of this
disclosure (e.g., various ester based Group V base stocks and
viscosity modifiers) in the lubricating oil and the resulting
properties (kinematic viscosity, high temperature high shear
viscosity, TEOST deposits, Viscosity Index, CCS viscosity and SAE
oil viscosity grade) of the oils. Formulation details are shown in
weight percent based on the total weight percent of the
formulation, of various formulations.
[0017] FIG. 3 shows other inventive and comparative formulations of
this disclosure (e.g., various ester based Group V base stocks and
viscosity modifiers) in the lubricating oil and the resulting
properties (kinematic viscosity, high temperature high shear
viscosity, TEOST deposits, Viscosity Index, CCS viscosity and SAE
oil viscosity grade) of the oils.
[0018] FIG. 4 shows still other inventive and comparative
formulations of this disclosure (e.g., various ester based Group V
base stocks and viscosity modifiers) in the lubricating oil and the
resulting properties (kinematic viscosity, high temperature high
shear viscosity, TEOST deposits, Viscosity Index, CCS viscosity and
SAE oil viscosity grade) of the oils.
[0019] FIG. 5 shows still yet other inventive and comparative
formulations of this disclosure (e.g., various ester based Group V
base stocks and viscosity modifiers) in the lubricating oil and the
resulting properties (kinematic viscosity, high temperature high
shear viscosity, TEOST deposits, Viscosity Index, CCS viscosity and
SAE oil viscosity grade) of the oils.
DETAILED DESCRIPTION
[0020] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art. The phrase "major amount" or "major component" as it
relates to components included within the lubricating oils of the
specification and the claims means greater than or equal to 50 wt.
%, or greater than or equal to 60 wt. %, or greater than or equal
to 70 wt. %, or greater than or equal to 80 wt. %, or greater than
or equal to 90 wt. % based on the total weight of the lubricating
oil. The phrase "minor amount" or "minor component" as it relates
to components included within the lubricating oils of the
specification and the claims means less than 50 wt. %, or less than
or equal to 40 wt. %, or less than or equal to 30 wt. %, or greater
than or equal to 20 wt. %, or less than or equal to 10 wt. %, or
less than or equal to 5 wt. %, or less than or equal to 2 wt. %, or
less than or equal to 1 wt. %, based on the total weight of the
lubricating oil. The phrase "essentially free" as it relates to
components included within the lubricating oils of the
specification and the claims means that the particular component is
at 0 weight % within the lubricating oil, or alternatively is at
impurity type levels within the lubricating oil (less than 100 ppm,
or less than 20 ppm, or less than 10 ppm, or less than 1 ppm). The
phrase "other lubricating oil additives" as used in the
specification and the claims means other lubricating oil additives
that are not specifically recited in the particular section of the
specification or the claims. For example, other lubricating oil
additives may include, but are not limited to, an anti-wear
additive, antioxidant, detergents, dispersant, pour point
depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, anti-rust
additive, friction modifier and combinations thereof.
[0021] It has now been found that improved fuel efficiency can be
attained, while deposit control is unexpectedly maintained or
improved, in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil that has at least one ester
based Group V base stock and at least one viscosity modifier in the
lubricating oil. The formulated oil preferably comprises a first
lubricating oil base stock, a second lubricating oil base stock
comprising at least one ester based Group V base stock and at least
one viscosity modifier. The lubricating oils of this disclosure are
particularly advantageous as passenger vehicle engine oil (PVEO)
products.
[0022] The lubricating oils of this disclosure provide a low
kinematic viscosity at 25 deg. C. as a measure of fuel efficiency
improvement and a low TEOST 33C deposits as measure of deposit
control improvement. In particular, the lubricating oils of this
disclosure provide a novel combination of a kinematic viscosity at
25 deg. C. of less than or equal to 125 cSt and a TEOST 33C total
deposits of less than or equal to 60 mg. A lower HTHS viscosity
engine oil also generally provides superior fuel economy to a
higher HTHS viscosity product.
[0023] In one form of the present disclosure, provided is a
lubricating engine oil that includes from 20 to 85 wt % of a first
lubricating oil base stock selected from the group consisting of a
Group I base stock, a Group II base stock, a Group III base stock,
a Group IV base stock, and combinations thereof; from 5 to 55 wt %
of a second lubricating oil base stock comprising at least one
ester based Group V base stock; from 5 to 20 wt % of at least one
viscosity modifier. The remainder of the lubricating engine oil
includes one or more other lubricating oil additives. The inventive
lubricating engine oil provides improved fuel efficiency properties
(kinematic viscosity at 25 deg. C. of less than or equal to 125
cSt) and maintained or improved deposit control (TEOST 33C total
deposits less than or equal to 60 mg) as compared to fuel
efficiency properties and deposit control achieved using a
lubricating engine oil not containing the at least one ester based
Group V base stock and the at least one viscosity modifier. The
kinematic viscosity at 25 deg. C. and the TEOST 33C total deposits
achieved using the inventive lubricating engine oil are
significantly and surprisingly improved compared to lubricating
engine oils not containing the at least one ester based Group V
base stock and the at least one viscosity modifier.
[0024] The one or more other lubricating oil additives constitute
the remainder of the formulated oil and are selected from one or
more of the following: an anti-wear additive, antioxidant,
detergents, dispersant, pour point depressant, corrosion inhibitor,
metal deactivator, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, friction modifier and combinations
thereof. These one or more other lubricating oil additives are
described in greater detail below.
[0025] In another form of the present disclosure, provided is a
method for improving fuel efficiency, while maintaining or
improving deposit control, in an engine lubricated with a
lubricating oil by using as the lubricating engine oil a formulated
oil, said formulated oil having a composition including: from 20 to
85 wt % of a first lubricating oil base stock selected from the
group consisting of a Group I base stock, a Group II base stock, a
Group III base stock, a Group IV base stock, and combinations
thereof from 5 to 55 wt % of a second lubricating oil base stock
comprising at least one ester based Group V base stock; from 5 to
20 wt % of at least one viscosity modifier. The remainder of the
lubricating engine oil includes one or more other lubricating oil
additives. The inventive lubricating engine oil provides improved
fuel efficiency properties (kinematic viscosity at 25 deg. C. of
less than or equal to 125 cSt) and maintained or improved deposit
control (TEOST 33C total deposits less than or equal to 60 mg) as
compared to fuel efficiency properties and deposit control achieved
using a lubricating engine oil not containing the at least one
ester based Group V base stock and the at least one viscosity
modifier. The kinematic viscosity at 25 deg. C. and the TEOST 33C
total deposits achieved using the inventive lubricating engine oil
are significantly and surprisingly improved compared to lubricating
engine oils not containing the at least one ester based Group V
base stock and the at least one viscosity modifier.
[0026] The inventive lubricating engine oils described above have a
kinematic viscosity, according to ASTM standards, of 8 cSt to 15
cSt (or mm.sup.2/s) at 100.degree. C., preferably of 9 cSt to 14
cSt (or mm.sup.2/s) at 100.degree. C., more preferably of 10 cSt to
13 cSt (or mm.sup.2/s) at 100.degree. C., and even more preferably
of 11 cSt to 12 cSt (or mm.sup.2/s) at 100.degree. C.
[0027] The inventive lubricating engine oils described above have a
low temperature kinematic viscosity (25 deg. C.), according to ASTM
standards, of less than or equal to 125 cSt at 25.degree. C., or
less than or equal to 110 cSt at 25.degree. C., or less than or
equal to 100 cSt at 25.degree. C., or less than or equal to 90 cSt
at 25.degree. C., or less than or equal to 80 cSt at 25.degree. C.,
less than or equal to 75 cSt at 25.degree. C. The low temperature
kinematic viscosity at 25 deg. C. correlates with improved fuel
efficiency with lower values preferred.
[0028] The inventive lubricating engine oils described above have a
high temperature high shear (HTHS) viscosity at 150.degree. C. as
measured by ASTM D4683 that ranges from 1.5 to 4.5 cP, or 1.75 to
4.25 cP, or 2.0 to 4.0 cP, or 2.25 to 3.75 cP, or 2.5 to 3.5 cP, or
2.75 to 3.25 cP.
[0029] The inventive lubricating engine oil and the inventive
method for improving fuel efficiency and deposit control provide
improved deposit control as measured by the TEOST 33C test to yield
total deposits less than or equal to 60 mg, or less than or equal
to 50 mg, or less than or equal to 40 mg, or less than or equal to
30 mg, or less than or equal to 20 mg, or less than or equal to 10
mg.
[0030] The inventive lubricating engine oils described above are
particularly suitable as a lubricating engine oil for a passenger
vehicle engine oil (PVEO). The inventive lubricating engine oils
described above are also particularly suitable as a lubricating
engine oil for an SAE viscosity grade motor oil selected from
0W-30, 5W-30, 0W-20, 5W-20, 0W-16, 5W-16, 0W-12, 5W-12, 0W-8, and
5W-8.
Lubricating Oil Base Stocks
[0031] The lubricating engine oils of the instant disclosure
include a combination of a first lubricating oil base stock and a
second lubricating oil base stock. The first lubricating oil base
stock is selected from the group consisting of a Group I base
stock, a Group II base stock, a Group III base stock, a Group IV
base stock, and combinations thereof. The second lubricating oil
base stock includes at least one ester based Group V base stock.
Non-limiting exemplary ester based Group V base stocks of the
instant disclosure include a monoester, a di-ester, a polyol ester,
a complex ester or mixtures thereof derived from a renewable
biological material and combinations thereof. The renewable
biological material may be derived from coconut oil, palm oil,
rapeseed oil, soy oil, vegetable oil, or sunflower oil.
[0032] Advantageous ester based Group V base stocks of the instant
disclosure include a C8/C10/C12/C14/C16/C18 Estolide ester, a
C11/C13/C15/C17 Estolide ester, a C8/C10 trimethyloipropane (IMP)
ester, a C6/C7/C8/C10 TMP ester, a C5/C6/C7/C8/C9/C10 TMP ester, a
C8/C10/C12/C14/C16/C18/C20 TMP ester, a C7/C8/C10 TMP ester, a
C7/C9/C11/C13/C15 TMP ester, a C6/C7/C9 TMP ester, a C6/C7/C9 TMP
ester, a C4/C5/C6/C7/C8/C9 TMP ester, a C15/C17 propylene glycol
diester, a C16/C18 propylene glycol diester and combinations
thereof.
[0033] The first lubricating oil base stock constitutes from 20 to
85 wt %, or 25 to 80 wt %, or 30 to 75 wt %, or 35 to 70 wt %, or
40 to 65 wt %, or 45 to 60 wt % of the total weight of the
lubricating engine oil. The second lubricating oil base stock
constitutes from 5 to 55 wt %, or 10 to 50 wt %, or 15 to 45 wt %,
or 20 to 40 wt %, or 25 to 35 wt % of the total weight of the
lubricating engine oil. In one advantageous form of the lubricating
engine oils disclosed herein, the at least one ester based Group V
base stock comprises from 25 to 55 wt % of the total weight of the
lubricating engine oil. In another advantageous form of the
lubricating engine oils disclosed herein, the first lubricating oil
base stock is a combination of a Group III gas to liquids (GTL)
base stock and a Group IV polyalphaolefin (PAO) base stock. In an
even more advantageous form, the GTL ranges from 20 to 75 wt % of
the lubricating engine oil and the PAO ranges from 2 to 10 wt % of
the lubricating engine oil. For the Group III GTL base stock and
the Group IV PAO base stocks, particularly advantageous viscosity
grades are those having a kinematic viscosity at 100 deg. C. of 4
cSt, or 6 cSt, or 8 cSt.
[0034] Non-limiting exemplary first and second lubricating oil base
stocks and their properties of the instant disclosure are shown in
FIG. 1. Further details of the Group I, Group II, Group III, Group
IV and ester based Group V base stocks of the instant disclosure
are described below.
[0035] Lubricating base oils that are useful in the present
disclosure are both natural oils, and synthetic oils, and
unconventional oils (or mixtures thereof) can be used unrefined,
refined, or rerefined (the latter is also known as reclaimed or
reprocessed oil). Unrefined oils are those obtained directly from a
natural or synthetic source and used without added purification.
These include shale oil obtained directly from retorting
operations, petroleum oil obtained directly from primary
distillation, and ester oil obtained directly from an
esterification process. Refined oils are similar to the oils
discussed for unrefined oils except refined oils are subjected to
one or more purification steps to improve at least one lubricating
oil property. One skilled in the art is familiar with many
purification processes. These processes include solvent extraction,
secondary distillation, acid extraction, base extraction,
filtration, and percolation. Rerefined oils are obtained by
processes analogous to refined oils but using an oil that has been
previously used as a feed stock.
[0036] Groups I, II, III, IV and V are broad base oil stock
categories developed and defined by the American Petroleum
Institute (API Publication 1509; www.API.org) to create guidelines
for lubricant base oils. Group I base stocks have a viscosity index
of between 80 to 120 and contain greater than 0.03% sulfur and/or
less than 90% saturates. Group II base stocks have a viscosity
index of between 80 to 120, and contain less than or equal to 0.03%
sulfur and greater than or equal to 90% saturates. Group III stocks
have a viscosity index greater than 120 and contain less than or
equal to 0.03% sulfur and greater than 90% saturates. Group IV
includes polyalphaolefins (PAO). Group V base stock includes base
stocks not included in Groups I-IV. Table 1 below summarizes
properties of each of these five groups.
TABLE-US-00001 TABLE 1 Base Oil Properties Saturates Sulfur
Viscosity Index Group I .sup. <90 and/or >0.03% and
.gtoreq.80 and <120 Group II .gtoreq.90 and .ltoreq.0.03% and
.gtoreq.80 and <120 Group III .gtoreq.90 and .ltoreq.0.03% and
.gtoreq.120 Group IV Polyalphaolefins (PAO) Group V All other base
oil stocks not included in Groups I, II, III or IV
[0037] Natural oils include animal oils, vegetable oils (castor oil
and lard oil, for example), and mineral oils. Animal and vegetable
oils possessing favorable thermal oxidative stability can be used.
Of the natural oils, mineral oils are preferred. Mineral oils vary
widely as to their crude source, for example, as to whether they
are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils
derived from coal or shale are also useful. Natural oils vary also
as to the method used for their production and purification, for
example, their distillation range and whether they are straight run
or cracked, hydrorefined, or solvent extracted.
[0038] Group II and/or Group III hydroprocessed or hydrocracked
basestocks, including synthetic oils such as polyalphaolefins,
alkyl aromatics and synthetic esters are also well known basestock
oils.
[0039] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
for example). Polyalphaolefin (PAO) oil base stocks are commonly
used synthetic hydrocarbon oil. By way of example, PAOs derived
from C.sub.6, C.sub.8, C.sub.10, C.sub.12, C.sub.14 olefins or
mixtures thereof may be utilized. See U.S. Pat. Nos. 4,956,122;
4,827,064; and 4,827,073.
[0040] The number average molecular weights of the PAOs, which are
known materials and generally available on a major commercial scale
from suppliers such as ExxonMobil Chemical Company, Chevron
Phillips Chemical Company, BP, and others, typically vary from 250
to 3,000, although PAO's may be made in viscosities up to 100 cSt
(100.degree. C.). The PAOs are typically comprised of relatively
low molecular weight hydrogenated polymers or oligomers of
alphaolefins which include, but are not limited to, C.sub.2 to
C.sub.32 alphaolefins with the C.sub.8 to C.sub.16 alphaolefins,
such as 1-hexene, 1-octene, 1-decene, 1-dodecene and the like,
being preferred. The preferred polyalphaolefins are poly-1-hexene,
poly-1-octene, poly-1-decene and poly-1-dodecene and mixtures
thereof and mixed olefin-derived polyolefins. However, the dimers
of higher olefins in the range of C.sub.14 to C.sub.18 may be used
to provide low viscosity base stocks of acceptably low volatility.
Depending on the viscosity grade and the starting oligomer, the
PAOs may be predominantly trimers and tetramers of the starting
olefins, with minor amounts of the higher oligomers, having a
viscosity range of 1.5 to 12 cSt. PAO fluids of particular use may
include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof.
Bi-modal mixtures of PAO fluids having a viscosity range of 1.5 to
100 cSt may be used if desired.
[0041] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as the Friedel-Crafts catalysts
including, for example, aluminum trichloride, boron trifluoride or
complexes of boron trifluoride with water, alcohols such as
ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods
disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be
conveniently used herein. Other descriptions of PAO synthesis are
found in the following U.S. Pat. Nos. 3,742,082; 3,769,363;
3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355;
4,956,122; and 5,068,487. The dimers of the C.sub.14 to C.sub.18
olefins are described in U.S. Pat. No. 4,218,330.
[0042] Other useful lubricant oil base stocks include wax isomerate
base stocks and base oils, comprising hydroisomerized waxy stocks
(e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker
bottoms, etc.), hydroisomerized Fischer-Tropsch waxes,
Gas-to-Liquids (GTL) base stocks and base oils, and other wax
isomerate hydroisomerized base stocks and base oils, or mixtures
thereof Fischer-Tropsch waxes, the high boiling point residues of
Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with
very low sulfur content. The hydroprocessing used for the
production of such base stocks may use an amorphous
hydrocracking/hydroisomerization catalyst, such as one of the
specialized lube hydrocracking (LHDC) catalysts or a crystalline
hydrocracking/hydroisomerization catalyst, preferably a zeolitic
catalyst. For example, one useful catalyst is ZSM-48 as described
in U.S. Pat. No. 5,075,269, the disclosure of which is incorporated
herein by reference in its entirety. Processes for making
hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in
U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as
well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and
1,390,359. Each of the aforementioned patents is incorporated
herein in their entirety. Particularly favorable processes are
described in European Patent Application Nos. 464546 and 464547,
also incorporated herein by reference. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172
and 4,943,672, the disclosures of which are incorporated herein by
reference in their entirety.
[0043] Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived
base oils, and other wax-derived hydroisomerized (wax isomerate)
base oils be advantageously used in the instant disclosure, and may
have useful kinematic viscosities at 100.degree. C. of 3 cSt to 50
cSt, preferably 3 cSt to 30 cSt, more preferably 3.5 cSt to 25 cSt,
as exemplified by GTL 4 with kinematic viscosity of 4.0 cSt at
100.degree. C. and a viscosity index of 141. These Gas-to-Liquids
(GTL) base oils, Fischer-Tropsch wax derived base oils, and other
wax-derived hydroisomerized base oils may have useful pour points
of -20.degree. C. or lower, and under some conditions may have
advantageous pour points of -25.degree. C. or lower, with useful
pour points of -30.degree. C. to -40.degree. C. or lower. Useful
compositions of Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax
derived base oils, and wax-derived hydroisomerized base oils are
recited in U.S. Pat. Nos. 6,080,301; 6,090,989, and 6,165,949 for
example, and are incorporated herein in their entirety by
reference.
[0044] The hydrocarbyl aromatics can be used as base oil or base
oil component and can be any hydrocarbyl molecule that contains at
least 5% of its weight derived from an aromatic moiety such as a
benzenoid moiety or naphthenoid moiety, or their derivatives. These
hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes,
alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides,
alkylated bis-phenol A, alkylated thiodiphenol, and the like. The
aromatic can be mono-alkylated, dialkylated, polyalkylated, and the
like. The aromatic can be mono- or poly-functionalized. The
hydrocarbyl groups can also be comprised of mixtures of alkyl
groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl
groups and other related hydrocarbyl groups. The hydrocarbyl groups
can range from C.sub.6 up to C.sub.60 with a range of C.sub.8 to
C.sub.20 often being preferred. A mixture of hydrocarbyl groups is
often preferred, and up to three such substituents may be present.
The hydrocarbyl group can optionally contain sulfur, oxygen, and/or
nitrogen containing substituents. The aromatic group can also be
derived from natural (petroleum) sources, provided at least 5% of
the molecule is comprised of an above-type aromatic moiety.
Viscosities at 100.degree. C. of approximately 3 cSt to 50 cSt are
preferred, with viscosities of approximately 3.4 cSt to 20 cSt
often being more preferred for the hydrocarbyl aromatic component.
In one embodiment, an alkyl naphthalene where the alkyl group is
primarily comprised of 1-hexadecene is used. Other alkylates of
aromatics can be advantageously used. Naphthalene or methyl
naphthalene, for example, can be alkylated with olefins such as
octene, decene, dodecene, tetradecene or higher, mixtures of
similar olefins, and the like. Useful concentrations of hydrocarbyl
aromatic in a lubricant oil composition can be 2% to 25%,
preferably 4% to 20%, and more preferably 4% to 15%, depending on
the application.
[0045] Alkylated aromatics such as the hydrocarbyl aromatics of the
present disclosure may be produced by well-known Friedel-Crafts
alkylation of aromatic compounds. See Friedel-Crafts and Related
Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York,
1963. For example, an aromatic compound, such as benzene or
naphthalene, is alkylated by an olefin, alkyl halide or alcohol in
the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and
Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See
Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many
homogeneous or heterogeneous, solid catalysts are known to one
skilled in the art. The choice of catalyst depends on the
reactivity of the starting materials and product quality
requirements. For example, strong acids such as AlCl.sub.3,
BF.sub.3, or HF may be used. In some cases, milder catalysts such
as FeCl.sub.3 or SnCl.sub.4 are preferred. Newer alkylation
technology uses zeolites or solid super acids.
[0046] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of monocarboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0047] Particularly useful synthetic esters are those which are
obtained by reacting one or more polyhydric alcohols, preferably
the hindered polyols (such as the neopentyl polyols, e.g.,
neopentyl glycol, trimethylol ethane,
2-methyl-2-propyl-1,3-propanediol, trimethylol propane,
pentaerythritol and dipentaerythritol) with alkanoic acids
containing at least 4 carbon atoms, preferably C.sub.5 to C.sub.30
acids such as saturated straight chain fatty acids including
caprylic acid, capric acid, lauric acid, myristic acid, palmitic
acid, stearic acid, arachic acid, and behenic acid, or the
corresponding branched chain fatty acids or unsaturated fatty acids
such as oleic acid, or mixtures of any of these materials.
[0048] Suitable synthetic ester components include the esters of
trimethylol propane (TMP), trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more
monocarboxylic acids containing from 5 to 10 carbon atoms. These
esters are widely available commercially, for example, the Mobil
P-41 and P-51 esters of ExxonMobil Chemical Company.
[0049] Also useful are esters derived from renewable material such
as coconut, palm, rapeseed, soy, sunflower and the like. These
esters may be monoesters, di-esters, polyol esters, complex esters,
or mixtures thereof. These esters are widely available
commercially, for example, the Mobil P-51 ester of ExxonMobil
Chemical Company. Engine oil formulations containing renewable
esters may also be included in this disclosure.
[0050] Other useful fluids of lubricating viscosity include
non-conventional or unconventional base stocks that have been
processed, preferably catalytically, or synthesized to provide high
performance lubrication characteristics.
[0051] Non-conventional or unconventional base stocks/base oils
include one or more of a mixture of base stock(s) derived from one
or more Gas-to-Liquids (GTL) materials, as well as
isomerate/isodewaxate base stock(s) derived from natural wax or
waxy feeds, mineral and or non-mineral oil waxy feed stocks such as
slack waxes, natural waxes, and waxy stocks such as gas oils, waxy
fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal
crackates, or other mineral, mineral oil, or even non-petroleum oil
derived waxy materials such as waxy materials received from coal
liquefaction or shale oil, and mixtures of such base stocks.
[0052] GTL materials are materials that are derived via one or more
synthesis, combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds, hydrogen-containing compounds and/or elements as feed
stocks such as hydrogen, carbon dioxide, carbon monoxide, water,
methane, ethane, ethylene, acetylene, propane, propylene, propyne,
butane, butylenes, and butynes. GTL base stocks and/or base oils
are GTL materials of lubricating viscosity that are generally
derived from hydrocarbons; for example, waxy synthesized
hydrocarbons, that are themselves derived from simpler gaseous
carbon-containing compounds, hydrogen-containing compounds and/or
elements as feed stocks. GTL base stock(s) and/or base oil(s)
include oils boiling in the lube oil boiling range (1)
separated/fractionated from synthesized GTL materials such as, for
example, by distillation and subsequently subjected to a final wax
processing step which involves either or both of a catalytic
dewaxing process, or a solvent dewaxing process, to produce lube
oils of reduced/low pour point; (2) synthesized wax isomerates,
comprising, for example, hydrodewaxed or hydroisomerized cat and/or
solvent dewaxed synthesized wax or waxy hydrocarbons; (3)
hydrodewaxed or hydroisomerized cat and/or solvent dewaxed
Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy
hydrocarbons, waxes and possible analogous oxygenates); preferably
hydrodewaxed or hydroisomerized/followed by cat and/or solvent
dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or
hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T
waxes, or mixtures thereof.
[0053] GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially, hydrodewaxed or hydroisomerized/followed by
cat and/or solvent dewaxed wax or waxy feed, preferably F-T
material derived base stock(s) and/or base oil(s), are
characterized typically as having kinematic viscosities at
100.degree. C. of from 2 mm.sup.2/s to 50 mm.sup.2/s (ASTM D445).
They are further characterized typically as having pour points of
-5.degree. C. to -40.degree. C. or lower (ASTM D97). They are also
characterized typically as having viscosity indices of 80 to 140 or
greater (ASTM D2270).
[0054] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) typically have very low sulfur and
nitrogen content, generally containing less than 10 ppm, and more
typically less than 5 ppm of each of these elements. The sulfur and
nitrogen content of GTL base stock(s) and/or base oil(s) obtained
from F-T material, especially F-T wax, is essentially nil. In
addition, the absence of phosphorus and aromatics make this
materially especially suitable for the formulation of low SAP
products.
[0055] The term GTL base stock and/or base oil and/or wax isomerate
base stock and/or base oil is to be understood as embracing
individual fractions of such materials of wide viscosity range as
recovered in the production process, mixtures of two or more of
such fractions, as well as mixtures of one or two or more low
viscosity fractions with one, two or more higher viscosity
fractions to produce a blend wherein the blend exhibits a target
kinematic viscosity.
[0056] The GTL material, from which the GTL base stock(s) and/or
base oil(s) is/are derived is preferably an F-T material (i.e.,
hydrocarbons, waxy hydrocarbons, wax).
[0057] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) and hydrodewaxed, or
hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or
base oil(s) typically have very low sulfur and nitrogen content,
generally containing less than 10 ppm, and more typically less than
5 ppm of each of these elements. The sulfur and nitrogen content of
GTL base stock(s) and/or base oil(s) obtained from F-T material,
especially F-T wax, is essentially nil. In addition, the absence of
phosphorus and aromatics make this material especially suitable for
the formulation of low sulfur, sulfated ash, and phosphorus (low
SAP) products.
[0058] Base oils for use in the formulated lubricating oils useful
in the present disclosure are any of the variety of oils
corresponding to API Group I, Group II, Group III, Group IV, and
Group V oils and mixtures thereof, preferably API Group II, Group
III, Group IV, and Group V oils and mixtures thereof, more
preferably the Group III to Group V base oils due to their
exceptional volatility, stability, viscometric and cleanliness
features. Minor quantities of Group I stock, such as the amount
used to dilute additives for blending into formulated lube oil
products, can be tolerated but should be kept to a minimum, i.e.
amounts only associated with their use as diluent/carrier oil for
additives used on an "as-received" basis. Even in regard to the
Group II stocks, it is preferred that the Group II stock be in the
higher quality range associated with that stock, i.e. a Group II
stock having a viscosity index in the range 100<VI<120.
[0059] The inventive base oils or base stocks described above have
a kinematic viscosity, according to ASTM standards, of 2.5 cSt to
12 cSt (or mm.sup.2/s) at 100.degree. C., preferably of 2.5 cSt to
9 cSt (or mm.sup.2/s) at 100.degree. C., more preferably of 4 cSt
to 8 cSt (or mm.sup.2/s) at 100.degree. C., and even more
preferably of 4 cSt to 6 cSt (or mm.sup.2/s) at 100.degree. C.
Viscosity Modifiers
[0060] The lubricating engine oils of the instant disclosure
include at least one viscosity modifier (also known as viscosity
index improvers, VI improvers, and viscosity improvers) as part of
the formulated oil. The at least one viscosity modifier may be
included in the formulated engine oil at from 5 to 22 wt %, or 7 to
20 wt %, or 9 to 18 wt %, or 11 to 16 wt %, or 13 to 14 wt % based
on the total weight of the engine oil.
[0061] Viscosity modifiers provide lubricants with high and low
temperature operability. These additives impart shear stability at
elevated temperatures and acceptable viscosity at low
temperatures.
[0062] Suitable viscosity modifiers include high molecular weight
hydrocarbons, polyesters and viscosity index improver dispersants
that function as both a viscosity index improver and a dispersant.
Typical molecular weights of these polymers are between 10,000 to
1,500,000, more typically 20,000 to 1,200,000, and even more
typically between 50,000 and 1,000,000.
[0063] Examples of suitable viscosity modifiers are linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes. Polyisobutylene is a commonly used
viscosity modifier. Another suitable viscosity modifier is
polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity modifiers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, and polyacrylates (copolymers
of various chain length acrylates, for example). Specific examples
include styrene-isoprene or styrene-butadiene based polymers of
50,000 to 200,000 molecular weight.
[0064] Olefin copolymers, are commercially available from Chevron
Oronite Company LLC under the trade designation "PARATONE.RTM."
(such as "PARATONE.RTM. 8921" and "PARATONE.RTM. 8941"); from Afton
Chemical Corporation under the trade designation "HiTEC.RTM." (such
as "HiTEC.RTM. 5850B"; and from The Lubrizol Corporation under the
trade designation "Lubrizol.RTM. 7067C". Polyisoprene polymers are
commercially available from Infineum International Limited, e.g.
under the trade designation "SV200"; diene-styrene copolymers are
commercially available from Infineum International Limited, e.g.
under the trade designation "SV 260".
[0065] Particularly advantageous viscosity modifiers of the
lubricating engine oils of the instant disclosure are linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, alkylated styrenes or combinations thereof. Other
particularly advantageous viscosity modifiers of the lubricating
engine oils of the instant disclosure are polyisobutylene,
polymethacrylate, polyisoprene, copolymers of ethylene and
propylene, hydrogenated block copolymers of styrene and isoprene,
styrene-butadiene based polymers, star polyisoprene polymers, star
polyisoprene-styrene copolymers and combinations thereof. In one
particularly preferred lubricating engine oil of the instant
disclosure, the at least one viscosity modifier is a styrene
isoprene copolymer having a molecular weight of from 50,000 to
200,000.
[0066] Viscosity modifiers are typically added as concentrates to
the lubricating oil, in large amounts of diluent oil.
Other Additives
[0067] The formulated lubricating oil useful in the present
disclosure may additionally contain one or more of the other
commonly used lubricating oil performance additives including but
not limited to antiwear agents, dispersants, detergents, friction
modifiers, organic metallic friction modifiers, corrosion
inhibitors, rust inhibitors, metal deactivators, extreme pressure
additives, anti-seizure agents, wax modifiers, fluid-loss
additives, seal compatibility agents, lubricity agents,
anti-staining agents, chromophoric agents, defoamants,
demulsifiers, emulsifiers, densifiers, wetting agents, gelling
agents, tackiness agents, colorants, and others. For a review of
many commonly used additives, see Klamann in Lubricants and Related
Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0.
Reference is also made to "Lubricant Additives" by M. W. Ranney,
published by Noyes Data Corporation of Parkridge, N J (1973); see
also U.S. Pat. No. 7,704,930, the disclosure of which is
incorporated herein in its entirety. These additives are commonly
delivered with varying amounts of diluent oil that may range from 5
weight percent to 50 weight percent.
[0068] The types and quantities of performance additives used in
combination with the instant disclosure in lubricant compositions
are not limited by the examples shown herein as illustrations.
Friction Modifiers
[0069] A friction modifier is any material or materials that can
alter the coefficient of friction of a surface lubricated by any
lubricant or fluid containing such material(s). Friction modifiers,
also known as friction reducers, or lubricity agents or oiliness
agents, and other such agents that change the ability of base oils,
formulated lubricant compositions, or functional fluids, to modify
the coefficient of friction of a lubricated surface may be
effectively used in combination with the base oils or lubricant
compositions of the present disclosure if desired. Friction
modifiers that lower the coefficient of friction are particularly
advantageous in combination with the base oils and lube
compositions of this disclosure.
[0070] Illustrative friction modifiers may include, for example,
organometallic compounds or materials, or mixtures thereof.
Illustrative organometallic friction modifiers useful in the
lubricating engine oil formulations of this disclosure include, for
example, molybdenum amine, molybdenum diamine, an
organotungstenate, a molybdenum dithiocarbamate, molybdenum
dithiophosphates, molybdenum amine complexes, molybdenum
carboxylates, and the like, and mixtures thereof. Similar tungsten
based compounds may be preferable.
[0071] Other illustrative friction modifiers useful in the
lubricating engine oil formulations of this disclosure include, for
example, alkoxylated fatty acid esters, alkanolamides, polyol fatty
acid esters, borated glycerol fatty acid esters, fatty alcohol
ethers, and mixtures thereof.
[0072] Illustrative alkoxylated fatty acid esters include, for
example, polyoxyethylene stearate, fatty acid polyglycol ester, and
the like. These can include polyoxypropylene stearate,
polyoxybutylene stearate, polyoxyethylene isosterate,
polyoxypropylene isostearate, polyoxyethylene palmitate, and the
like.
[0073] Illustrative alkanolamides include, for example, lauric acid
diethylalkanolamide, palmic acid diethylalkanolamide, and the like.
These can include oleic acid diethyalkanolamide, stearic acid
diethylalkanolamide, oleic acid diethylalkanolamide,
polyethoxylated hydrocarbylamides, polypropoxylated
hydrocarbylamides, and the like.
[0074] Illustrative polyol fatty acid esters include, for example,
glycerol mono-oleate, saturated mono-, di-, and tri-glyceride
esters, glycerol mono-stearate, and the like. These can include
polyol esters, hydroxyl-containing polyol esters, and the like.
[0075] Illustrative borated glycerol fatty acid esters include, for
example, borated glycerol mono-oleate, borated saturated mono-,
di-, and tri-glyceride esters, borated glycerol mono-sterate, and
the like. In addition to glycerol polyols, these can include
trimethylolpropane, pentaerythritol, sorbitan, and the like. These
esters can be polyol monocarboxylate esters, polyol dicarboxylate
esters, and on occasion polyoltricarboxylate esters. Preferred can
be the glycerol mono-oleates, glycerol dioleates, glycerol
trioleates, glycerol monostearates, glycerol distearates, and
glycerol tristearates and the corresponding glycerol
monopalmitates, glycerol dipalmitates, and glycerol tripalmitates,
and the respective isostearates, linoleates, and the like. On
occasion the glycerol esters can be preferred as well as mixtures
containing any of these. Ethoxylated, propoxylated, butoxylated
fatty acid esters of polyols, especially using glycerol as
underlying polyol can be preferred.
[0076] Illustrative fatty alcohol ethers include, for example,
stearyl ether, myristyl ether, and the like. Alcohols, including
those that have carbon numbers from C.sub.3 to C.sub.50, can be
ethoxylated, propoxylated, or butoxylated to form the corresponding
fatty alkyl ethers. The underlying alcohol portion can preferably
be stearyl, myristyl, C.sub.11-C.sub.13 hydrocarbon, oleyl,
isosteryl, and the like.
[0077] The lubricating oils of this disclosure exhibit desired
properties, e.g., wear control, in the presence or absence of a
friction modifier.
[0078] Useful concentrations of friction modifiers may range from
0.01 weight percent to 5 weight percent, or about 0.1 weight
percent to about 2.5 weight percent, or about 0.1 weight percent to
about 1.5 weight percent, or about 0.1 weight percent to about 1
weight percent. Concentrations of molybdenum-containing materials
are often described in terms of Mo metal concentration.
Advantageous concentrations of Mo may range from 25 ppm to 700 ppm
or more, and often with a preferred range of 50-200 ppm. Friction
modifiers of all types may be used alone or in mixtures with the
materials of this disclosure. Often mixtures of two or more
friction modifiers, or mixtures of friction modifier(s) with
alternate surface active material(s), are also desirable.
[0079] In addition to the friction modifiers described above,
organic metallic friction modifiers may also be used in the
lubricating engine oil formulations of this disclosure.
[0080] Illustrative organic metallic friction modifiers useful in
the lubricating engine oil formulations of this disclosure include,
for example, molybdenum amine, molybdenum diamine, an
organotungstenate, a molybdenum dithiocarbamate, molybdenum
dithiophosphates, molybdenum amine complexes, molybdenum
carboxylates, and the like. Similar tungsten based compounds may be
preferable. Useful concentrations of the organic metallic friction
modifiers may range from 0.01 weight percent to 5 weight percent,
or 0.1 weight percent to 2.5 weight percent. Useful concentration
of molybdenum can range from 25 to 700 ppm, or more preferably from
50 to 200 ppm.
[0081] Organic molybdenum containing friction modifiers are
particularly preferred for the friction modifier mixture of the
lubricating oils and the method for improving fuel efficiency and
reducing frictional properties, while maintaining or improving
deposit control, in an engine lubricated with a lubricating oil of
the instant disclosure. The organic molybdenum containing friction
modifier is selected from the group consisting of trimeric
molybdenum carbamate, moly amine moly ester, molybdenum amine,
molybdenum diamine, molybdenum dithiocarbamate, molybdenum
dithiophosphates, molybdenum amine complexes, molybdenum
carboxylates and combinations thereof. The organic molybdenum
containing friction modifier in the friction modifier mixture
contributes elemental molybdenum to the lubricating engine oil that
yields an elemental molybdenum level in the lubricating engine oil
of from 80 to 500 ppm, or 100 to 490 ppm, or 150 to 485 ppm, or 200
to 480 ppm, or 220 to 460 ppm, or 240 to 440 ppm, or 260 to 420
ppm, or 280 to 400 ppm, or 300 to 380 ppm, or 320 to 360 ppm of the
lubricating engine oil.
Antiwear Additive
[0082] A metal alkylthiophosphate and more particularly a metal
dialkyl dithio phosphate in which the metal constituent is zinc, or
zinc dialkyl dithio phosphate (ZDDP) is a useful component of the
lubricating oils of this disclosure. ZDDP can be derived from
primary alcohols, secondary alcohols or mixtures thereof. ZDDP
compounds generally are of the formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2 where R.sup.1 and R.sup.2 are
C.sub.1-C.sub.18 alkyl groups, preferably C.sub.2-C.sub.12 alkyl
groups. These alkyl groups may be straight chain or branched.
Alcohols used in the ZDDP can be 2-propanol, butanol, secondary
butanol, pentanols, hexanols such as 4-methyl-2-pentanol,
n-hexanol, n-octanol, 2-ethyl hexanol, alkylated phenols, and the
like. Mixtures of secondary alcohols or of primary and secondary
alcohol can be preferred. Alkyl aryl groups may also be used.
[0083] Preferable zinc dithiophosphates which are commercially
available include secondary zinc dithiophosphates such as those
available from for example, The Lubrizol Corporation under the
trade designations "LZ 677A", "LZ 1095" and "LZ 1371", from for
example Chevron Oronite under the trade designation "OLOA 262" and
from for example Afton Chemical under the trade designation "HITEC
7169".
[0084] The ZDDP is typically used in amounts of from 0.4 weight
percent to 1.2 weight percent, preferably from 0.5 weight percent
to 1.0 weight percent, and more preferably from 0.6 weight percent
to 0.8 weight percent, based on the total weight of the lubricating
oil, although more or less can often be used advantageously.
Preferably, the ZDDP is a secondary ZDDP and present in an amount
of from 0.6 to 1.0 weight percent of the total weight of the
lubricating oil.
[0085] In another form, the zinc dialkyl dithio phosphate (ZDDP)
anti-wear additive may be included in the lubricating oil at from 0
to 1.1 wt. %, or 0.1 to 1.0 wt. %, or 0.2 to 0.9 wt. %, or 0.3 to
0.8 wt. %, or 0.4 to 0.7 wt. % of the lubricating engine oil. In
this form, the elemental phosphorus level in the lubricating engine
oil may range from 0 to 760 ppm, or 100 to 600 ppm, or 150 to 550
ppm, or 200 to 500 ppm, or 250 to 450 ppm, or 300 to 400 ppm of the
lubricating engine oil.
[0086] Low phosphorus engine oil formulations are included in this
disclosure. For such formulations, the phosphorus content is
typically less than 0.12 weight percent preferably less than 0.10
weight percent and most preferably less than 0.085 weight percent.
Low phosphorus can be preferred in combination with the friction
modifier mixture.
Detergents
[0087] Illustrative detergents useful in this disclosure include,
for example, alkali metal detergents, alkaline earth metal
detergents, or mixtures of one or more alkali metal detergents and
one or more alkaline earth metal detergents. A typical detergent is
an anionic material that contains a long chain hydrophobic portion
of the molecule and a smaller anionic or oleophobic hydrophilic
portion of the molecule. The anionic portion of the detergent is
typically derived from an organic acid such as a sulfur acid,
carboxylic acid, phosphorus acid, phenol, or mixtures thereof. The
counterion is typically an alkaline earth or alkali metal.
[0088] Salts that contain a substantially stochiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) with an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly
overbased, or highly overbased. These detergents can be used in
mixtures of neutral, overbased, highly overbased calcium
salicylate, sulfonates, phenates and/or magnesium salicylate,
sulfonates, phenates. The TBN ranges can vary from low, medium to
high TBN products, including as low as 0 to as high as 600.
Mixtures of low, medium, high TBN can be used, along with mixtures
of calcium and magnesium metal based detergents, and including
sulfonates, phenates, salicylates, and carboxylates. A detergent
mixture with a metal ratio of 1, in conjunction of a detergent with
a metal ratio of 2, and as high as a detergent with a metal ratio
of 5, can be used. Borated detergents can also be used.
[0089] Alkaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH).sub.2, BaO, Ba(OH).sub.2,
MgO, Mg(OH).sub.2, for example) with an alkyl phenol or sulfurized
alkylphenol. Useful alkyl groups include straight chain or branched
C.sub.1-C.sub.30 alkyl groups, preferably, C.sub.4-C.sub.20 or
mixtures thereof. Examples of suitable phenols include
isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol,
and the like. It should be noted that starting alkylphenols may
contain more than one alkyl substituent that are each independently
straight chain or branched and can be used from 0.5 to 6 weight
percent. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These
methods include heating a mixture of alkylphenol and sulfurizing
agent (including elemental sulfur, sulfur halides such as sulfur
dichloride, and the like) and then reacting the sulfurized phenol
with an alkaline earth metal base.
[0090] Metal salts of carboxylic acids are also useful as
detergents. These carboxylic acid detergents may be prepared by
reacting a basic metal compound with at least one carboxylic acid
and removing free water from the reaction product. These compounds
may be overbased to produce the desired TBN level. Detergents made
from salicylic acid are one preferred class of detergents derived
from carboxylic acids. Useful salicylates include long chain alkyl
salicylates. One useful family of compositions is of the
formula
##STR00001##
where R is an alkyl group having 1 to 30 carbon atoms, n is an
integer from 1 to 4, and M is an alkaline earth metal. Preferred R
groups are alkyl chains of at least C.sub.11, preferably C.sub.13
or greater. R may be optionally substituted with substituents that
do not interfere with the detergent's function. M is preferably,
calcium, magnesium, or barium. More preferably, M is calcium.
[0091] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The
metal salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0092] Alkaline earth metal phosphates are also used as detergents
and are known in the art.
[0093] Detergents may be simple detergents or what is known as
hybrid or complex detergents. The latter detergents can provide the
properties of two detergents without the need to blend separate
materials. See U.S. Pat. No. 6,034,039.
[0094] Preferred detergents include calcium phenates, calcium
sulfonates, calcium salicylates, magnesium phenates, magnesium
sulfonates, magnesium salicylates and other related components
(including borated detergents), and mixtures thereof. Preferred
mixtures of detergents include magnesium sulfonate and calcium
salicylate, magnesium sulfonate and calcium sulfonate, magnesium
sulfonate and calcium phenate, calcium phenate and calcium
salicylate, calcium phenate and calcium sulfonate, calcium phenate
and magnesium salicylate, calcium phenate and magnesium
phenate.
[0095] The detergent concentration in the lubricating oils of this
disclosure can range from 1.0 to 6.0 weight percent, preferably 2.0
to 5.0 weight percent, and more preferably from 2.0 weight percent
to 4.0 weight percent, based on the total weight of the lubricating
oil.
[0096] One particularly preferred detergent for the inventive
lubricating engine oil and the inventive method for improving fuel
efficiency, frictional properties and deposit control is an
overbased calcium salicylate detergent and a magnesium sulfonate or
a calcium sulfonate detergent. The overbased calcium salicylate
detergent may be included in the formulated oil at from 0.5 to 2.5
wt %, or 1.0 to 2.0 wt %, or 1.2 to 1.8 wt %. The magnesium
sulfonate or a calcium sulfonate detergent may also be included in
the formulated oil at from 0.5 to 2.5 wt %, or 1.0 to 2.0 wt %, or
1.2 to 1.8 wt %. The overbased calcium salicylate detergent may
also be included in the formulated oil such that it contributes
elemental calcium based on the weight of the lubricating engine oil
of from 200 ppm to 2000 ppm, or 300 to 1900 ppm, or 400 to 1800
ppm, or 500 to 1600 ppm, or 600 to 1500 ppm, or 700 to 1400 ppm, or
800 to 1300 ppm, or 900 to 1200 ppm.
[0097] In another form of this disclosure, mixtures of an overbased
calcium salicylate detergent and a magnesium sulfonate or a calcium
sulfonate detergent provide for advantageous lubricating engine
oils and advantageous methods for improving fuel efficiency,
frictional properties and deposit control. The magnesium sulfonate
or a calcium sulfonate detergent may also be included in the
formulated oil at from 0.5 to 2.5 wt %, or 1.0 to 2.0 wt %, or 1.2
to 1.8 wt %.
[0098] As used herein, the detergent concentrations are given on an
"as delivered" basis. Typically, the active detergent is delivered
with a process oil. The "as delivered" detergent typically contains
from 20 weight percent to 80 weight percent, or from 40 weight
percent to 60 weight percent, of active detergent in the "as
delivered" detergent product.
Dispersants
[0099] During engine operation, oil-insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposition on metal surfaces. Dispersants
used in the formulation of the lubricating oil may be ashless or
ash-forming in nature. Preferably, the dispersant is ashless.
So-called ashless dispersants are organic materials that form
substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents
discussed above form ash upon combustion.
[0100] Suitable dispersants typically contain a polar group
attached to a relatively high molecular weight hydrocarbon chain.
The polar group typically contains at least one element of
nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain
50 to 400 carbon atoms.
[0101] A particularly useful class of dispersants are the
alkenylsuccinic derivatives, typically produced by the reaction of
a long chain hydrocarbyl substituted succinic compound, usually a
hydrocarbyl substituted succinic anhydride, with a polyhydroxy or
polyamino compound. The long chain hydrocarbyl group constituting
the oleophilic portion of the molecule which confers solubility in
the oil, is normally a polyisobutylene group. Many examples of this
type of dispersant are well known commercially and in the
literature. Exemplary U.S. patents describing such dispersants are
U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177;
3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511;
3,787,374 and 4,234,435. Other types of dispersant are described in
U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554;
3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277;
3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565;
3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further
description of dispersants may be found, for example, in European
Patent Application No. 471 071, to which reference is made for this
purpose.
[0102] Hydrocarbyl-substituted succinic acid and
hydrocarbyl-substituted succinic anhydride derivatives are useful
dispersants. In particular, succinimide, succinate esters, or
succinate ester amides prepared by the reaction of a
hydrocarbon-substituted succinic acid compound preferably having at
least 50 carbon atoms in the hydrocarbon substituent, with at least
one equivalent of an alkylene amine are particularly useful,
although on occasion, having a hydrocarbon substituent between
20-50 carbon atoms can be useful.
[0103] Succinimides are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and amines. Molar
ratios can vary depending on the polyamine. For example, the molar
ratio of hydrocarbyl substituted succinic anhydride to TEPA can
vary from 1:1 to 5:1. Representative examples are shown in U.S.
Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670;
and 3,652,616, 3,948,800; and Canada Patent No. 1,094,044.
[0104] Succinate esters are formed by the condensation reaction
between hydrocarbyl substituted succinic anhydrides and alcohols or
polyols. Molar ratios can vary depending on the alcohol or polyol
used. For example, the condensation product of a hydrocarbyl
substituted succinic anhydride and pentaerythritol is a useful
dispersant.
[0105] Succinate ester amides are formed by condensation reaction
between hydrocarbyl substituted succinic anhydrides and alkanol
amines. For example, suitable alkanol amines include ethoxylated
polyalkylpolyamines, propoxylated polyalkylpolyamines and
polyalkenylpolyamines such as polyethylene polyamines. One example
is propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305.
[0106] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range
between 800 and 2,500 or more. The above products can be
post-reacted with various reagents such as sulfur, oxygen,
formaldehyde, carboxylic acids such as oleic acid. The above
products can also be post reacted with boron compounds such as
boric acid, borate esters or highly borated dispersants, to form
borated dispersants generally having from 0.1 to 5 moles of boron
per mole of dispersant reaction product.
[0107] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No.
4,767,551, which is incorporated herein by reference. Process aids
and catalysts, such as oleic acid and sulfonic acids, can also be
part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S.
Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953;
3,798,165; and 3,803,039.
[0108] Typical high molecular weight aliphatic acid modified
Mannich condensation products useful in this disclosure can be
prepared from high molecular weight alkyl-substituted
hydroxyaromatics or HNR2 group-containing reactants.
[0109] Hydrocarbyl substituted amine ashless dispersant additives
are well known to one skilled in the art; see, for example, U.S.
Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209,
and 5,084,197.
[0110] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
500 to 5000, or from 1000 to 3000, or 1000 to 2000, or a mixture of
such hydrocarbylene groups, often with high terminal vinylic
groups. Other preferred dispersants include succinic acid-esters
and amides, alkylphenol-polyamine-coupled Mannich adducts, their
capped derivatives, and other related components. Such additives
may be used in an amount of 0.1 to 20 weight percent, preferably
0.5 to 8 weight percent, or more preferably 0.5 to 4 weight
percent. On an active ingredient basis, such additives may be used
in an amount of 0.06 to 14 weight percent, preferably 0.3 to 6
weight percent. The hydrocarbon portion of the dispersant atoms can
range from C.sub.60 to C.sub.400, or from C.sub.70 to C.sub.300, or
from C.sub.70 to C.sub.200. These dispersants may contain both
neutral and basic nitrogen, and mixtures of both. Dispersants can
be end-capped by borates and/or cyclic carbonates.
[0111] One particularly preferred dispersant for the inventive
lubricating engine oil and the inventive method for improving fuel
efficiency, frictional properties and deposit control is a
non-borated polyisobutenyl bis-succinimide (PIBSA) dispersant. The
non-borated PIBSA dispersant may be included in the formulated oil
at from 2.0 to 6.0 wt %, or 3.0 to 5.0 wt %, or 3.5 to 4.5 wt
%.
[0112] As used herein, the dispersant concentrations are given on
an "as delivered" basis. Typically, the active dispersant is
delivered with a process oil. The "as delivered" dispersant
typically contains from 20 weight percent to 80 weight percent, or
from 40 weight percent to 60 weight percent, of active dispersant
in the "as delivered" dispersant product.
Antioxidants
[0113] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricating oil compositions. See,
Klamann in Lubricants and Related Products, op cite, and U.S. Pat.
Nos. 4,798,684 and 5,084,197, for example.
[0114] Useful antioxidants include hindered phenols. These phenolic
antioxidants may be ashless (metal-free) phenolic compounds or
neutral or basic metal salts of certain phenolic compounds. Typical
phenolic antioxidant compounds are the hindered phenolics which are
the ones which contain a sterically hindered hydroxyl group, and
these include those derivatives of dihydroxy aryl compounds in
which the hydroxyl groups are in the o- or p-position to each
other. Typical phenolic antioxidants include the hindered phenols
substituted with C.sub.6+ alkyl groups and the alkylene coupled
derivatives of these hindered phenols. Examples of phenolic
materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl
phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant disclosure. Examples of ortho-coupled
phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol);
2,2'-bis(4-octyl-6-t-butyl-phenol); and
2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0115] Effective amounts of one or more catalytic antioxidants may
also be used. The catalytic antioxidants comprise an effective
amount of a) one or more oil soluble polymetal organic compounds;
and, effective amounts of b) one or more substituted
N,N'-diaryl-o-phenylenediamine compounds or c) one or more hindered
phenol compounds; or a combination of both b) and c). Catalytic
antioxidants are more fully described in U.S. Pat. No. 8,048,833,
herein incorporated by reference in its entirety.
[0116] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.12 is H, alkyl, aryl or R.sup.11S(O).sub.XR.sup.12 where
R.sup.11 is an alkylene, alkenylene, or aralkylene group, R.sup.12
is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and
x is 0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to
20 carbon atoms, and preferably contains from 6 to 12 carbon atoms.
The aliphatic group is a saturated aliphatic group. Preferably,
both R.sup.8 and R.sup.9 are aromatic or substituted aromatic
groups, and the aromatic group may be a fused ring aromatic group
such as naphthyl. Aromatic groups R.sup.8 and R.sup.9 may be joined
together with other groups such as S.
[0117] Typical aromatic amines antioxidants have alkyl substituent
groups of at least 6 carbon atoms. Examples of aliphatic groups
include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the
aliphatic groups will not contain more than 14 carbon atoms. The
general types of amine antioxidants useful in the present
compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines.
Mixtures of two or more aromatic amines are also useful. Polymeric
amine antioxidants can also be used. Particular examples of
aromatic amine antioxidants useful in the present disclosure
include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0118] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0119] Preferred antioxidants include hindered phenols, arylamines.
These antioxidants may be used individually by type or in
combination with one another. Such additives may be used in an
amount of 0.01 to 5 weight percent, preferably 0.01 to 1.5 weight
percent, more preferably zero to less than 1.5 weight percent, more
preferably zero to less than 1 weight percent.
Pour Point Depressants (PPDs)
[0120] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
disclosure if desired. These pour point depressant may be added to
lubricating compositions of the present disclosure to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
polymethacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2,721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Such additives may be
used in an amount of 0.01 to 5 weight percent, preferably 0.01 to
1.5 weight percent.
Seal Compatibility Agents
[0121] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, alkoxysulfonlanes (C.sub.10 alcohol,
for example), aromatic esters, aromatic hydrocarbons, esters
(butylbenzyl phthalate, for example), and polybutenyl succinic
anhydride. Such additives may be used in an amount of 0.01 to 3
weight percent, preferably 0.01 to 2 weight percent.
Antifoam Agents
[0122] Antifoam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical antifoam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Antifoam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 weight
percent and often less than 0.1 weight percent.
Inhibitors and Antirust Additives
[0123] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available.
[0124] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of 0.01 to 5 weight percent, preferably 0.01
to 1.5 weight percent.
[0125] When lubricating oil compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
disclosure are shown in Table 2 below.
[0126] It is noted that many of the additives are shipped from the
additive manufacturer as a concentrate, containing one or more
additives together, with a certain amount of base oil diluents.
Accordingly, the weight amounts in the table below, as well as
other amounts mentioned herein, are directed to the amount of
active ingredient (that is the non-diluent portion of the
ingredient). The weight percent (wt %) indicated below is based on
the total weight of the lubricating oil composition.
TABLE-US-00002 TABLE 2 Typical Amounts of Other Lubricating Oil
Components Approximate wt % Approximate wt % Compound (Useful)
(Preferred) Dispersant 0.1-20 0.1-8 Detergent 0.1-20 0.1-8 Friction
Modifier 0.01-5 0.01-1.5 Antioxidant 0.1-5 0.1-1.5 Pour Point
Depressant 0.0-5 0.01-1.5 (PPD) Anti-foam Agent 0.001-3 0.001-0.15
Viscosity modifier (solid 0.1-2 0.1-1 polymer basis) Anti-wear
0.1-2 0.5-1 Inhibitor and Antirust 0.01-5 0.01-1.5
[0127] The foregoing additives are all commercially available
materials. These additives may be added independently but are
usually precombined in packages which can be obtained from
suppliers of lubricant oil additives. Additive packages with a
variety of ingredients, proportions and characteristics are
available and selection of the appropriate package will take the
requisite use of the ultimate composition into account.
[0128] The following non-limiting examples are provided to
illustrate the disclosure.
EXAMPLES
Example 1
[0129] Comparative and inventive lubricating engine oils were
prepared according to the formulations shown in FIGS. 2-5.
Formulation details are shown in weight percent based on the total
weight percent of the formulation, of the various comparative and
inventive formulations. FIG. 1 shows the various base stocks and
the properties of the base stocks used in accordance with the
lubricating engine oils of FIGS. 2-5. Seven different ester based
Group V base stocks (second lubricating oil base stock) were
evaluated in combination with a first lubricating oil base stock
(GTL4, GTL8, PAO-4, PAO-6 or combinations thereof). The inventive
and comparative lubricating engine oils also included at least one
viscosity modifier. The five different viscosity modifiers (VM)
evaluated either individually or in combination with one another
were 1) a polymethacrylate comb VM, 2) a star VM containing
styrene, 3) a styrene isoprene diblock VM solid polymer, 4) an
isoprene star VM containing styrene in star arms and 5) an ethylene
propylene OCP VM. The lubricating engine oils also included other
lubricating oil additives, which were held constant in terms of
compositional ingredients and weight loading (13.95 or 13.95 wt %)
of the total lubricating engine oil. The SAE oil viscosity grade of
all the lubricating engine oils were 0W-30 or 5W-30.
[0130] The comparative and inventive lubricating engine oils were
bench tested or evaluated for Kinematic viscosity at 25, 40 and 100
deg. C. measured by ASTM D445, high temperature high shear
viscosity at 150 deg. C. measured by ASTM D4683, thermo-oxidation
engine oil simulation test (TEOST 33C deposits) measured by ASTM
D6335, Viscosity Index as measured by ASTM D2270, and CCS viscosity
at 25, 30 and 35 deg. C. as measured by D5293. The property results
for the comparative and inventive lubricating engine oils are also
depicted in FIGS. 2-5. All inventive examples were blended such
that the D4683 High Temperature High Shear viscosity was 3.5 cP.
This viscosity is a common requirement for many European
auto-builders.
[0131] The bench test results of FIGS. 2-5 show that the inventive
lubricating engine oils provide a low kinematic viscosity at 25
deg. C. as a measure of fuel efficiency improvement and a low TEOST
33C deposits as measure of deposit control improvement. In
particular, the inventive lubricating engine oils of FIGS. 2-5
provide a novel combination of a kinematic viscosity at 25 deg. C.
of less than or equal to 125 cSt and a TEOST 33C total deposits of
less than or equal to 60 mg. in comparison to the comparative
lubricating engine oils. The inventive lubricating engine oils
included a combination of from 20 to 85 wt % of a first lubricating
oil base stock including a GTL, a PAO and combinations thereof; and
from 5 to 55 wt % of a second lubricating oil base stock comprising
at least one ester based Group V base stock selected from the types
shown in FIGS. 2-5; and from 5 to 20 wt % of at least one viscosity
modifier selected from 1) a polymethacrylate comb VM, 2) a star VM
containing styrene, 3) a styrene isoprene diblock VM solid polymer,
4) an isoprene star VM containing styrene in star arms and 5) an
ethylene propylene OCP VM, and 6) combinations thereof. For the
inventive lubricating engine oils, the improvements in fuel
efficiencies as measured by KV at 25 deg. C. and deposit control as
measured by TEOST 33C were surprising and unexpected relative to
the prior art and the comparative lubricating engine oils.
Example 2
[0132] Comparative example 1 of FIG. 2 contains no Group V base
stock and no viscosity modifier. This formulation had a KV25C of
140 cSt, which is expected to provide unacceptable NEDC/WLTP fuel
economy performance. Comparative example 1 also failed to meet the
D4683 target of 3.5 cP. Comparative examples 11, 13, and 14 use a
star VM containing styrene, a star VM containing styrene in the
arms, and an ethylene propylene OCP VM respectively. However, these
formulations contain no Group V basestock. All three of these
examples met the D4683 target of 3.5 cP. However, all three of
these formulations failed to provide acceptable D6335 TEOST 33C
deposit control. Thus, the inclusion of at least one VM and one
Group V base stock was needed in each of the inventive examples of
FIGS. 2-5. For each of the following seven ester based Group V base
stocks (1=C11/C13/C15/C17 Estolide, 2=C8/C10 trimethylolpropane
(TMP) ester, 3=C7/C9/C11/C13/C15 TMP ester, 4=C6/C7/C9 TMP ester,
5=C15/C17 propylene glycol diester, 6=C6/C7/C9 TMP ester,
7=C4/C5/C6/C7/C8/C9 TMP ester), four different lubricating engine
oil formulations were evaluated (A-D in Table 3 below). Each
formulation contained an identical additive system but used a
combination of one of two ester treat rates (either 5% or 50% wt %
based on the total lubricating oil) with either a styrene isoprene
VM or a PMA VM. PMA VMs have been shown to improve fuel economy
because they generate a desirable viscosity vs. temperature
profile. Two formulations using PMA VMs were used as comparative
benchmarks in this example. The ester treat rates in these
formulations were 5 wt % (A) and 50 wt % (B) in combination with a
PMA VM. Reference formulations (C) contained 5 wt % ester and two
styrene isoprene VMs (1. styrene isoprene block copolymer and 2.
isoprene star polymer containing styrene in the arms). The
inventive lubricating engine oils of this Example contained 50%
ester and replaced the PMA VM with the two styrene isoprene VMs
indicated above. VM treat rates varied between 4.50 and 10.65 and
were adjusted to target an HTHS 150.degree. C. value of 3.5 as
determined by ASTM D4683. The seven esters tested were labeled as
Ester 1-7. Ester 1 is an Estolide ester, Ester 2-4 and 6-7 are TMP
esters and Ester 5 is a diester. The four different combinations of
VM/ester treat rate as shown below in Table 3 and are labeled A
through D.
TABLE-US-00003 TABLE 3 Ester treat rate, % VM type A 5 PMA B 50 PMA
C 5 Styrene isoprene D 50 Styrene isoprene
[0133] Therefore, each formulation was labeled with the ester used
in the formulation (1-7) and the combination of VM type and ester
treat rate (A-D). Each formulation was tested for turbocharger
deposit control in ASTM D6335 TEOST 33C test and KV at 25.degree.
C. (which was used to rank the performance of the oils in NEDC and
WLTP fuel economy tests). Having a KV 25.degree. C..ltoreq.125 cSt
is advantageous for fuel efficiency. In addition, TEOST 33C
deposits of less than or equal to 60 mg is considered advantageous
for engine cleanliness. For each ester, formulation A (5% ester+PMA
VM) exhibited greater than 60 mg total deposits, while formulation
D (50% ester+styrene isoprene VM) exhibited less than 60 mg
deposits.
[0134] For each ester, formulation D (50% ester+styrene isoprene
VM) showed a KV at 25.degree. C. value between 78.6 and
107.8.degree. C., which is expected to provide excellent
performance in NEDC and WLTP fuel economy tests. Formulation A (5%
ester+PMA VM) showed lower KV values resulting in higher FEI
predictions. The reference formulations C (5% ester+styrene
isoprene VM) exhibited KV@25.degree. C. values ranging from 118.1
to 123.9.degree. C. and thus are expected to provide acceptable
results in NEDC and WLTP fuel economy tests.
[0135] All patents and patent applications, test procedures (such
as ASTM methods, UL methods, and the like), and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this disclosure and for all
jurisdictions in which such incorporation is permitted.
[0136] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the disclosure
have been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the disclosure. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present disclosure, including all features
which would be treated as equivalents thereof by those skilled in
the art to which the disclosure pertains.
[0137] The present disclosure has been described above with
reference to numerous embodiments and specific examples. Many
variations will suggest themselves to those skilled in this art in
light of the above detailed description. All such obvious
variations are within the full intended scope of the appended
claims.
* * * * *
References