U.S. patent application number 12/133013 was filed with the patent office on 2009-06-04 for engine oil compositions with improved fuel economy performance.
This patent application is currently assigned to Chevron U.S.A. Inc.. Invention is credited to Matthew Ansari, Max I. Chang, Satoshi Hirano, Kenji Takeoka.
Application Number | 20090143261 12/133013 |
Document ID | / |
Family ID | 40676357 |
Filed Date | 2009-06-04 |
United States Patent
Application |
20090143261 |
Kind Code |
A1 |
Takeoka; Kenji ; et
al. |
June 4, 2009 |
Engine Oil Compositions with Improved Fuel Economy Performance
Abstract
An engine lubricating oil exhibiting a fuel economy improvement
is disclosed. The engine oil composition meets at least one of
ILSAC GF-4, API CI-4, API CJ4, ACEA A1, ACEA A5, ACEA B1, ACEA B5,
ACEA C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1 performance
specifications. The composition comprises at least an isomerized
base oil comprising a consecutive number of carbon atoms and having
a CCS Viscosity at -35.degree. C. of less than or equal to 7000
mPa, a T.sub.95-T.sub.5 boiling range distribution of less than or
equal to 200.degree. C., a ratio of weight percent molecules with
monocycloparaffinic functionality to weight percent molecules with
multicycloparaffinic functionality of greater than 15, and an
Oxidator BN of greater than 30 hours; and 0.05 to 40 wt %. of at
least an additive selected from the group of metal detergents,
dispersants, wear inhibitors, anti-oxidants, friction modifiers,
viscosity modifiers, corrosion inhibitors, seal swelling agents,
metal deactivators, anti-foamants, and mixtures thereof.
Inventors: |
Takeoka; Kenji; (San Rafael,
CA) ; Ansari; Matthew; (San Ramon, CA) ;
Hirano; Satoshi; (Nagoya city, JP) ; Chang; Max
I.; (Chao Chu Kang, SG) |
Correspondence
Address: |
CHEVRON CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron U.S.A. Inc.
|
Family ID: |
40676357 |
Appl. No.: |
12/133013 |
Filed: |
June 4, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60991296 |
Nov 30, 2007 |
|
|
|
Current U.S.
Class: |
508/110 |
Current CPC
Class: |
C10N 2030/02 20130101;
C10N 2020/015 20200501; C10M 2205/173 20130101; C10N 2040/25
20130101; C10M 107/02 20130101; C10N 2030/54 20200501; C10N 2030/06
20130101; C10N 2030/10 20130101; C10N 2020/069 20200501; C10N
2020/065 20200501; C10N 2020/067 20200501; C10N 2030/74 20200501;
C10N 2020/071 20200501 |
Class at
Publication: |
508/110 |
International
Class: |
C10M 105/02 20060101
C10M105/02 |
Claims
1. An engine oil composition meeting at least one of ILSAC GF-4,
API CI-4, API CJ4, ACEA A1, ACEA A5, ACEA B1, ACEA B5, ACEA C1,
ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1 performance
specifications, the composition comprising: at least an isomerized
base oil comprising a consecutive number of carbon atoms and having
a CCS Viscosity at -35.degree. C. of less than or equal to 7000
mPa, a T.sub.95-T.sub.5 boiling range distribution of less than or
equal to 200.degree. C., a ratio of weight percent molecules with
monocycloparaffinic functionality to weight percent molecules with
multicycloparaffinic functionality of greater than 15, and an
Oxidator BN of greater than 30 hours; and 0.05 to 40 wt %. of at
least an additive selected from the group of metal detergents,
dispersants, wear inhibitors, anti-oxidants, friction modifiers,
viscosity modifiers, corrosion inhibitors, seal swelling agents,
metal deactivators, anti-foamants, and mixtures thereof.
2. The engine oil composition of claim 1, wherein the composition
meets ILSAC GF-4 performance specification.
3. The engine oil composition of claim 1, where the composition
contains less than 0.3 wt. % of a friction modifier.
4. The engine oil composition of claim 2, wherein the composition
meets ILSAC GF-4 performance specification and wherein the
composition does not contain any added friction modifier.
5. The engine oil composition of claim 1, wherein the composition
exhibits a fuel economy improvement of greater than or equal to 1%
compared to an engine oil composition employing a non-isomerized
base oil, wherein the fuel economy improvement is measured by
summing Stage-4 and Stage-5 Phase I Sequence VIB Screener Test
results.
6. The engine oil composition of claim 5, wherein the fuel economy
improvement of greater than or equal to 1.5%.
7. The engine oil composition of claim 6, wherein the fuel economy
improvement of greater than or equal to 1.75%.
8. The engine oil composition of claim 1, wherein the isomerized
base oil has an Oxidator BN of at least 35 hours.
9. The engine oil composition of claim 1, wherein the isomerized
base oil has an Oxidator BN of at least 50 hours.
10. The engine oil composition of claim 1, wherein the isomerized
base oil has a viscosity index of at least 135.
11. The engine oil composition of claim 10, wherein the isomerized
base oil has a viscosity index of at least 140.
12. The engine oil composition of claim 1, wherein the isomerized
base oil is a Fischer-Tropsch derived base oil made from a waxy
feed.
13. The engine oil composition of claim 1, wherein isomerized base
oil has an average degree of branching in the molecules between 6.5
and 10 alkyl branches per 100 carbon atoms.
14. The engine oil composition of claim 1, wherein the isomerized
base oil has a wt % Noack volatility between 0 and 100.
15. The engine oil composition of claim 1, wherein the isomerized
base oil has an auto-ignition temperature (AIT) greater than an
amount defined by: 1.6.times.(Kinematic Viscosity at 40.degree. C.,
in mm.sup.2/s)+300.
16. The engine oil composition of claim 1, wherein the isomerized
base oil has a total weight percent of molecules with
cycloparaffinic functionality of greater than 10.
17. The engine oil composition of claim 14, wherein the isomerized
base oil is made from a process in which the highly paraffinic wax
is hydroisomerized using a shape selective intermediate pore size
molecular sieve comprising a noble metal hydrogenation component,
and under conditions of about 600.degree. F. to 750.degree. F. and
wherein the isomerized base oil has a Noack volatility of less than
50 weight %.
18. The engine oil composition of claim 14, wherein the isomerized
base oil comprises greater than 3 weight % molecules with
cycloparaffinic functionality and less than 0.30 weight percent
aromatics.
19. The engine oil composition of claim 14, wherein the isomerized
base oil has a traction coefficient of less than 0.023 when
measured at a kinematic viscosity of 15 mm.sup.2/s and at a slide
to roll ratio of 40%.
20. The engine oil composition of claim 1, wherein the engine oil
composition exhibits an MRV of less than or equal to 12,000 mPa at
-40.degree. C.
21. The engine oil composition of claim 20, wherein the engine oil
composition exhibits an MRV of less than or equal to 8,800 mPa at
-40.degree. C.
22. The engine oil composition of claim 21, wherein the engine oil
composition exhibits an MRV of less than or equal to 7,330 mPa at
-40.degree. C.
23. The engine oil composition of claim 1, wherein the engine oil
composition exhibits a CCS Viscosity at -35.degree. C. of less than
or equal to 1400 mPa.
24. The engine oil composition of claim 22, wherein the engine oil
composition exhibits a CCS Viscosity at -35.degree. C. of less than
or equal to 1200 mPa.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit under 35 USC 119 of
Provisional Application 60/991296 filed Nov. 30, 2007. This
application claims priority to and benefits from the foregoing, the
disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates generally to engine oil compositions.
In one embodiment, engine oil compositions with improved fuel
economy.
BACKGROUND
[0003] US government mandated standards for fuel economy and
emissions have placed increasing demands on passenger car
manufacturers. This in turn has resulted in automobile
manufacturers requesting high quality engine oils used for
passenger car motor oils (PCMOs).
[0004] Starting in 1995, automakers requested higher quality engine
oils to help meet stringent federally mandated passenger car fuel
economy and emissions standards. The International Lubricant
Standardization and Approval Committee (ILSAC), working with API,
ASTM, and SAE previously proposed a GF-3 Minimum Performance
Standards for Passenger Car Motor Oils (PCMO) with significantly
improved fuel economy and volatility requirements compared to
previous GF-1 and GF-2 PCMO standards. In January 2004, ILSAC
issued its latest Minimum Performance Standard for Engine Oils,
ILSAC GF-4. Besides improved fuel efficiency, GF-4 requirements
include improved oxidation resistance, improved high-temperature
deposit control, better cam and lifter wear discrimination,
improved low temperature wear protection, and improved low
temperature used oil pumpability. ILSAC GF-4 oils also have reduced
phosphorous and sulphur contents to provide enhanced emission
system protection.
[0005] During the last five years, the petroleum industry has
invested to make the higher viscosity index (VI) basestocks
necessary to help meet these new engine oil requirements. In a
number of patent publications and applications, i.e., US
2006/0289337, US2006/0201851, US2006/0016721, US2006/0016724,
US2006/0076267, US2006/020185, US2006/013210, US2005/0241990,
US2005/0077208, US2005/0139513, US2005/0139514, US2005/0133409,
US2005/0133407, US2005/0261147, US2005/0261146, US2005/0261145,
US2004/0159582, U.S. Pat. No. 7,018,525, U.S. Pat. No. 7,083,713,
U.S. application Ser. Nos. 11/400570, 11/535165 and 11/613936,
which are incorporated herein by reference, a Fischer Tropsch base
oil is produced from a process in which the feed is a waxy feed
recovered from a Fischer-Tropsch synthesis. The process comprises a
complete or partial hydroisomerization dewaxing step, using a
dual-functional catalyst or a catalyst that can isomerize paraffins
selectively. Hydroisomerization dewaxing is achieved by contacting
the waxy feed with a hydroisomerization catalyst in an
isomerization zone under hydroisomerizing conditions. The
Fischer-Tropsch synthesis products can be obtained by well-known
processes such as, for example, the commercial SASOL.RTM. Slurry
Phase Fischer-Tropsch technology, the commercial SHELL.RTM. Middle
Distillate Synthesis (SMDS) Process, or by the non-commercial
EXXON.RTM. Advanced Gas Conversion (AGC-21) process. Details of
these processes and others are described in, for example, EP-A-
776959, EP-A-668342; U.S. Pat. Nos. 4,943,672, 5,059,299,
5,733,839, and RE39073 ; and US Published Application No.
2005/0227866, WO-A-9934917, WO-A-9920720 and WO-A-05107935. The
Fischer-Tropsch synthesis product usually comprises hydrocarbons
having 1 to 100, or even more than 100 carbon atoms, and typically
includes paraffins, olefins and oxygenated products. Fischer
Tropsch is a viable process to generate clean alternative
hydrocarbon products.
[0006] There is still a need for engine oil compositions meeting
ILSAC GF-4 specifications, utilizing less common hydrocarbon
products and with improved fuel economy performance.
SUMMARY OF THE INVENTION
[0007] In one embodiment, there is provided an engine oil
composition meeting at least one of ILSAC GF-4, API CI-4, API CJ4,
ACEA A1, ACEA A5, ACEA B1, ACEA B5, ACEA C1, ACEA C2, ACEA C3, ACEA
C4A, and JASO DL-1 performance specifications, the composition
comprising at least an isomerized base oil comprising a consecutive
number of carbon atoms and having a CCS Viscosity at -35.degree. C.
of less than or equal to 7000 mPa, a T.sub.95-T.sub.5 boiling range
distribution of less than or equal to 200.degree. C., a ratio of
weight percent molecules with monocycloparaffinic functionality to
weight percent molecules with multicycloparaffinic functionality of
greater than 15, and an Oxidator BN of greater than 30 hours; and
0.05 to 40 wt %. of at least an additive selected from the group of
metal detergents, dispersants, wear inhibitors, anti-oxidants,
friction modifiers, viscosity modifiers, corrosion inhibitors, seal
swelling agents, metal deactivators, anti-foamants, and mixtures
thereof. The engine oil composition in one embodiment provides at
least 1% fuel savings over a composition of the prior art without
the isomerized base oil.
[0008] In another aspect, there is provided a method to improve
fuel efficiency in the operations of an automobile/vehicle, the
method comprises utilizing an engine oil composition at least an
isomerized base oil comprising a consecutive number of carbon atoms
and having a CCS Viscosity at -35.degree. C. of less than or equal
to 7000 mPa, a T.sub.95-T.sub.5 boiling range distribution of less
than or equal to 200.degree. C., a ratio of weight percent
molecules with monocycloparaffinic functionality to weight percent
molecules with multicycloparaffinic functionality of greater than
15, and an Oxidator BN of greater than 30 hours; and 0.05 to 40 wt
%. of at least an additive selected from the group of metal
detergents, dispersants, wear inhibitors, anti-oxidants, friction
modifiers, viscosity modifiers, corrosion inhibitors, seal swelling
agents, metal deactivators, anti-foamants, and mixtures
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1 and 2 are graphs comparing the Traction Coefficient
vs. Disk Speed of embodiments of engine oil compositions comprising
an isomerized base oil and embodiments of the engine oils of the
prior art, containing Group III base stock.
[0010] FIGS. 3 and 4 are graphs comparing the log.sub.10 Traction
Coefficient vs. Disk Speed at various slide to role ratio (SRR)
values of embodiments of engine oil compositions comprising an
isomerized base oil and embodiments of the engine oils of the prior
art, containing Group III base stock.
DETAILED DESCRIPTION
[0011] The following terms will be used throughout the
specification and will have the following meanings unless otherwise
indicated.
[0012] "Fischer-Tropsch derived" means that the product, fraction,
or feed originates from or is produced at some stage by a
Fischer-Tropsch process. As used herein, "Fischer-Tropsch base oil"
may be used interchangeably with "FT base oil," "FTBO," "GTL base
oil" (GTL: gas-to-liquid), or "Fischer-Tropsch derived base
oil."
[0013] As used herein, "isomerized base oil" refers to a base oil
made by isomerization of a waxy feed.
[0014] As used herein, a "waxy feed" comprises at least 40 wt %
n-paraffins. In one embodiment, the waxy feed comprises greater
than 50 wt % n-paraffins. In another embodiment, greater than 75 wt
% n-paraffins. In one embodiment, the waxy feed also has very low
levels of nitrogen and sulphur, e.g., less than 25 ppm total
combined nitrogen and sulfur, or in other embodiments less than 20
ppm. Examples of waxy feeds include slack waxes, deoiled slack
waxes, refined foots oils, waxy lubricant raffinates, n-paraffin
waxes, NAO waxes, waxes produced in chemical plant processes,
deoiled petroleum derived waxes, microcrystalline waxes,
Fischer-Tropsch waxes, and mixtures thereof In one embodiment, the
waxy feeds have a pour point of greater than 50.degree. C. In
another embodiment, greater than 60.degree. C.
[0015] "Kinematic viscosity" is a measurement in mm.sup.2/s of the
resistance to flow of a fluid under gravity, determined by ASTM
D445-06.
[0016] "Viscosity index" (VI) is an empirical, unit-less number
indicating the effect of temperature change on the kinematic
viscosity of the oil. The higher the VI of an oil, the lower its
tendency to change viscosity with temperature. Viscosity index is
measured according to ASTM D 2270-04.
[0017] Cold-cranking simulator apparent viscosity (CCS VIS) is a
measurement in millipascal seconds, mPa.s to measure the
viscometric properties of lubricating base oils under low
temperature and low shear. CCS VIS is determined by ASTM D
5293-04.
[0018] The boiling range distribution of base oil, by wt %, is
determined by simulated distillation (SIMDIS) according to ASTM D
6352-04, "Boiling Range Distribution of Petroleum Distillates in
Boiling Range from 174 to 700.degree. C. by Gas
Chromatography."
[0019] "Noack volatility" is defined as the mass of oil, expressed
in weight %, which is lost when the oil is heated at 250.degree. C.
with a constant flow of air drawn through it for 60 min., measured
according to ASTM D5800-05, Procedure B.
[0020] Brookfield viscosity is used to determine the internal
fluid-friction of a lubricant during cold temperature operation,
which can be measured by ASTM D 2983-04.
[0021] "Pour point" is a measurement of the temperature at which a
sample of base oil will begin to flow under certain carefully
controlled conditions, which can be determined as described in ASTM
D 5950-02.
[0022] "Auto ignition temperature" is the temperature at which a
fluid will ignite spontaneously in contact with air, which can be
determined according to ASTM 659-78.
[0023] "Ln" refers to natural logarithm with base "e."
[0024] "Traction coefficient" is an indicator of intrinsic
lubricant properties, expressed as the dimensionless ratio of the
friction force F and the normal force N, where friction is the
mechanical force which resists movement or hinders movement between
sliding or rolling surfaces. Traction coefficient can be measured
with an MTM Traction Measurement System from PCS Instruments, Ltd.,
configured with a polished 19 mm diameter ball (SAE AISI 52100
steel) angled at 220 to a flat 46 mm diameter polished disk (SAE
AISI 52100 steel). The steel ball and disk are independently
measured at an average rolling speed of 3 meters per second, a
slide to roll ratio of 40 percent, and a load of 20 Newtons. The
roll ratio is defined as the difference in sliding speed between
the ball and disk divided by the mean speed of the ball and disk,
i.e. roll ratio=(Speed1-Speed2)/((Speed1+Speed2)-/2).
[0025] As used herein, "consecutive numbers of carbon atoms" means
that the base oil has a distribution of hydrocarbon molecules over
a range of carbon numbers, with every number of carbon numbers
in-between. For example, the base oil may have hydrocarbon
molecules ranging from C22 to C36 or from C30 to C60 with every
carbon number in-between. The hydrocarbon molecules of the base oil
differ from each other by consecutive numbers of carbon atoms, as a
consequence of the waxy feed also having consecutive numbers of
carbon atoms. For example, in the Fischer-Tropsch hydrocarbon
synthesis reaction, the source of carbon atoms is CO and the
hydrocarbon molecules are built up one carbon atom at a time.
Petroleum-derived waxy feeds have consecutive numbers of carbon
atoms. In contrast to an oil based on poly-alpha-olefin ("PAO"),
the molecules of an isomerized base oil have a more linear
structure, comprising a relatively long backbone with short
branches. The classic textbook description of a PAO is a
star-shaped molecule, and in particular tridecane, which is
illustrated as three decane molecules attached at a central point.
While a star-shaped molecule is theoretical, nevertheless PAO
molecules have fewer and longer branches that the hydrocarbon
molecules that make up the isomerized base oil disclosed
herein.
[0026] "Molecules with cycloparaffinic functionality" mean any
molecule that is, or contains as one or more substituents, a
monocyclic or a fused multicyclic saturated hydrocarbon group.
[0027] "Molecules with monocycloparaffinic functionality" mean any
molecule that is a monocyclic saturated hydrocarbon group of three
to seven ring carbons or any molecule that is substituted with a
single monocyclic saturated hydrocarbon group of three to seven
ring carbons.
[0028] "Molecules with multicycloparaffinic functionality" mean any
molecule that is a fused multicyclic saturated hydrocarbon ring
group of two or more fused rings, any molecule that is substituted
with one or more fused multicyclic saturated hydrocarbon ring
groups of two or more fused rings, or any molecule that is
substituted with more than one monocyclic saturated hydrocarbon
group of three to seven ring carbons.
[0029] Molecules with cycloparaffinic functionality, molecules with
monocycloparaffinic functionality, and molecules with
multicycloparaffinic functionality are reported as weight percent
and are determined by a combination of Field Ionization Mass
Spectroscopy (FIMS), HPLC-UV for aromatics, and Proton NMR for
olefins, further fully described herein.
[0030] Oxidator BN measures the response of a lubricating oil in a
simulated application. High values, or long times to adsorb one
liter of oxygen, indicate good stability. Oxidator BN can be
measured via a Dornte-type oxygen absorption apparatus (R. W.
Dornte "Oxidation of White Oils," Industrial and Engineering
Chemistry, Vol. 28, page 26, 1936), under 1 atmosphere of pure
oxygen at 340.degree. F., time to absorb 1000 ml of O.sub.2 by 100
g. of oil is reported. In the Oxidator BN test, 0.8 ml of catalyst
is used per 100 grams of oil. The catalyst is a mixture of soluble
metal-naphthenates simulating the average metal analysis of used
crankcase oil. The additive package is 80 millimoles of zinc
bispolypropylenephenyldithiophosphate per 100 grams of oil.
[0031] Molecular characterizations can be performed by methods
known in the art, including Field Ionization Mass Spectroscopy
(FIMS) and n-d-M analysis (ASTM D 3238-95 (Re-approved 2005) with
normalization). In FIMS, the base oil is characterized as alkanes
and molecules with different numbers of unsaturations. The
molecules with different numbers of unsaturations may be comprised
of cycloparaffins, olefins, and aromatics. If aromatics are present
in significant amount, they would be identified as 4-unsaturations.
When olefins are present in significant amounts, they would be
identified as 1-unsaturations. The total of the 1-unsaturations,
2-unsaturations, 3-unsaturations, 4-unsaturations, 5-unsaturations,
and 6-unsaturations from the FIMS analysis, minus the wt % olefins
by proton NMR, and minus the wt % aromatics by HPLC-UV is the total
weight percent of molecules with cycloparaffinic functionality. If
the aromatics content was not measured, it was assumed to be less
than 0.1 wt % and not included in the calculation for total weight
percent of molecules with cycloparaffinic functionality. The total
weight percent of molecules with cycloparaffinic functionality is
the sum of the weight percent of molecules with monocyclopraffinic
functionality and the weight percent of molecules with
multicycloparaffinic functionality.
[0032] Molecular weights are determined by ASTM D2503-92(Reapproved
2002). The method uses thermoelectric measurement of vapour
pressure (VPO). In circumstances where there is insufficient sample
volume, an alternative method of ASTM D2502-04 may be used; and
where this has been used it is indicated.
[0033] Density is determined by ASTM D4052-96 (Reapproved 2002).
The sample is introduced into an oscillating sample tube and the
change in oscillating frequency caused by the change in the mass of
the tube is used in conjunction with calibration data to determine
the density of the sample.
[0034] Weight percent olefins can be determined by proton-NMR
according to the steps specified herein. In most tests, the olefins
are conventional olefins, i.e. a distributed mixture of those
olefin types having hydrogens attached to the double bond carbons
such as: alpha, vinylidene, cis, trans, and tri-substituted, with a
detectable allylic to olefin integral ratio between 1 and 2.5. When
this ratio exceeds 3, it indicates a higher percentage of tri or
tetra substituted olefins being present, thus other assumptions
known in the analytical art can be made to calculate the number of
double bonds in the sample. A solution of 5-10% of the sample in
deuterochloroform can be prepared, giving a normal proton spectrum
of at least 12 ppm spectral width. Tetramethylsilane (TMS) can be
used as an internal reference standard. The instrument used to
acquire the spectrum and reference the chemical shift has
sufficient gain range to acquire a signal without overloading the
receiver/ADC, with a minimum signal digitization dynamic range of
at least 65,000 when a 30 degree pulse is applied. The intensities
of the proton signals in the region of 0.5-1.9 ppm (methyl,
methylene and methine groups), 1.9-2.2 ppm (allylic) and between
6.0-4.5 ppm (olefin) are measured. Using the average molecular
weight (estimated by vapor pressure osmometry by ASTM D
2503-92[re-approved 2002]) of each distillate range paraffin feed,
the following can be calculated: (1) the average molecular formula
of the saturated hydrocarbons; (2) the average molecular formula of
the olefins; (3) the total integral intensity (i.e. the sum of all
the integral intensities); (4) the integral intensity per sample
hydrogen (i.e. the total integral intensity divided by the number
of hydrogens in the formula; (5) the number of olefin hydrogens
(i.e. the olefin integral divided by the integral per hydrogen);
(6) the number of double bonds (i.e. the olefin hydrogen multiplied
by the hydrogens in the olefin formula divided by 2); and (7) the
weight percent olefins (i.e. 100 multiplied by the number of double
bonds multiplied by the number of hydrogens in a typical olefin
molecule divided by the number of hydrogens in a typical distillate
range paraffin feed molecule). This Proton NMR procedure to
calculate the olefin content of the sample works best when the
olefin content is low, e.g., less than about 15 weight percent.
[0035] Weight percent aromatics in one embodiment can be measured
by HPLC-UV. In one embodiment, the test is conducted using a
Hewlett Packard 1050 Series Quaternary Gradient High Performance
Liquid Chromatography (HPLC) system, coupled with a HP 1050
Diode-Array UV-Vis detector interfaced to an HP Chem-station.
Identification of the individual aromatic classes in the highly
saturated base oil can be made on the basis of the UV spectral
pattern and the elution time. The amino column used for this
analysis differentiates aromatic molecules largely on the basis of
their ring- number (or double-bond number). Thus, the single ring
aromatic containing molecules elute first, followed by the
polycyclic aromatics in order of increasing double bond number per
molecule. For aromatics with similar double bond character, those
with only alkyl substitution on the ring elute sooner than those
with naphthenic substitution. Unequivocal identification of the
various base oil aromatic hydrocarbons from their UV absorbance
spectra can be accomplished recognizing that their peak electronic
transitions are all red-shifted relative to the pure model compound
analogs to a degree dependent on the amount of alkyl and naphthenic
substitution on the ring system. Quantification of the eluting
aromatic compounds can be made by integrating chromatograms made
from wavelengths optimized for each general class of compounds over
the appropriate retention time window for that aromatic. Retention
time window limits for each aromatic class can be determined by
manually evaluating the individual absorbance spectra of eluting
compounds at different times and assigning them to the appropriate
aromatic class based on their qualitative similarity to model
compound absorption spectra.
[0036] Weight percent aromatic carbon ("Ca"), weight percent
naphthenic carbon ("Cn") and weight percent paraffinic carbon
("Cp") in one embodiment can be measured by ASTM D3238-95
(Reapproved 2005) with normalization. ASTM D3238-95 (Reapproved
2005) is the Standard Test Method for Calculation of Carbon
Distribution and Structural Group Analysis of Petroleum Oils by the
n-d-M Method. This method is for "olefin free" feedstocks, i.e.,
having an olefin content of 2 wt % or less. The normalization
process consists of the following: A) If the Ca value is less than
zero, Ca is set to zero, and Cn and Cp are increased proportionally
so that the sum is 100%. B) If the Cn value is less than zero, Cn
is set to zero, and Ca and Cp are increased proportionally so that
the sum is 100%; and C) If both Cn and Ca are less than zero, Cn
and Ca are set to zero, and Cp is set to 100%.
[0037] HPLC-UV Calibration. In one embodiment, HPLC-UV can be used
for identifying classes of aromatic compounds even at very low
levels, e.g., multi-ring aromatics typically absorb 10 to 200 times
more strongly than single-ring aromatics. Alkyl-substitution
affects absorption by 20%. Integration limits for the co-eluting
1-ring and 2-ring aromatics at 272 nm can be made by the
perpendicular drop method. Wavelength dependent response factors
for each general aromatic class can be first determined by
constructing Beer's Law plots from pure model compound mixtures
based on the nearest spectral peak absorbances to the substituted
aromatic analogs. Weight percent concentrations of aromatics can be
calculated by assuming that the average molecular weight for each
aromatic class was approximately equal to the average molecular
weight for the whole base oil sample.
[0038] NMR analysis. In one embodiment, the weight percent of all
molecules with at least one aromatic function in the purified
mono-aromatic standard can be confirmed via long-duration carbon 13
NMR analysis. The NMR results can be translated from % aromatic
carbon to % aromatic molecules (to be consistent with HPLC-UV and D
2007) knowing that 95-99% of the aromatics in highly saturated base
oils are single-ring aromatics. In another test to accurately
measure low levels of all molecules with at least one aromatic
function by NMR, the standard D 5292-99 (Reapproved 2004) method
can be modified to give a minimum carbon sensitivity of 500:1 (by
ASTM standard practice E 386) with a 15-hour duration run on a
400-500 MHz NMR with a 10-12 mm Nalorac probe. Acorn PC integration
software can be used to define the shape of the baseline and
consistently integrate.
[0039] Extent of branching refers to the number of alkyl branches
in hydrocarbons. Branching and branching position can be determined
using carbon-13 (.sup.13C) NMR according to the following nine-step
process: 1) Identify the CH branch centers and the CH.sub.3 branch
termination points using the DEPT Pulse sequence (Doddrell, D. T.;
D. T. Pegg; M. R. Bendall, Journal of Magnetic Resonance 1982, 48,
323ff.). 2) Verify the absence of carbons initiating multiple
branches (quaternary carbons) using the APT pulse sequence (Patt,
S. L.; J. N. Shoolery, Journal of Magnetic Resonance 1982, 46,
535ff.). 3) Assign the various branch carbon resonances to specific
branch positions and lengths using tabulated and calculated values
known in the art (Lindeman, L. P., Journal of Qualitative
Analytical Chemistry 43, 1971 1245ff; Netzel, D. A., et. al., Fuel,
60, 1981, 307ff). 4) Estimate relative branching density at
different carbon positions by comparing the integrated intensity of
the specific carbon of the methyl/alkyl group to the intensity of a
single carbon (which is equal to total integral/number of carbons
per molecule in the mixture). For the 2-methyl branch, where both
the terminal and the branch methyl occur at the same resonance
position, the intensity is divided by two before estimating the
branching density. If the 4-methyl branch fraction is calculated
and tabulated, its contribution to the 4+methyls is subtracted to
avoid double counting. 5) Calculate the average carbon number. The
average carbon number is determined by dividing the molecular
weight of the sample by 14 (the formula weight of CH.sub.2). 6) The
number of branches per molecule is the sum of the branches found in
step 4. 7) The number of alkyl branches per 100 carbon atoms is
calculated from the number of branches per molecule (step 6) times
100/average carbon number. 8) Estimate Branching Index (BI) by
.sup.1H NMR Analysis, which is presented as percentage of methyl
hydrogen (chemical shift range 0.6-1.05 ppm) among total hydrogen
as estimated by NMR in the liquid hydrocarbon composition. 9)
Estimate Branching proximity (BP) by .sup.13C NMR, which is
presented as percentage of recurring methylene carbons--which are
four or more carbons away from the end group or a branch
(represented by a NMR signal at 29.9 ppm) among total carbons as
estimated by NMR in the liquid hydrocarbon composition. The
measurements can be performed using any Fourier Transform NMR
spectrometer, e.g., one having a magnet of 7.0 T or greater. After
verification by Mass Spectrometry, UV or an NMR survey that
aromatic carbons are absent, the spectral width for the .sup.13C
NMR studies can be limited to the saturated carbon region, 0-80 ppm
vs. TMS (tetramethylsilane). Solutions of 25-50 wt. % in
chloroform-d1 are excited by 30 degrees pulses followed by a 1.3
seconds (sec.) acquisition time. In order to minimize non-uniform
intensity data, the broadband proton inverse-gated decoupling is
used during a 6 sec. delay prior to the excitation pulse and on
during acquisition. Samples are doped with 0.03 to 0.05 M Cr
(acac).sub.3 (tris(acetylacetonato)-chromium (III)) as a relaxation
agent to ensure full intensities are observed. The DEPT and APT
sequences can be carried out according to literature descriptions
with minor deviations described in the Varian or Bruker operating
manuals. DEPT is Distortionless Enhancement by Polarization
Transfer. The DEPT 45 sequence gives a signal all carbons bonded to
protons. DEPT 90 shows CH carbons only. DEPT 135 shows CH and
CH.sub.3 up and CH.sub.2 180 degrees out of phase (down). APT is
attached proton test, known in the art. It allows all carbons to be
seen, but if CH and CH.sub.3 are up, then quaternaries and CH.sub.2
are down. The branching properties of the sample can be determined
by .sup.13C NMR using the assumption in the calculations that the
entire sample was iso-paraffinic. The unsaturates content may be
measured using Field Ionization Mass Spectroscopy (FIMS).
[0040] In one embodiment, the engine oil composition comprises
optional additives in a matrix of base oil or base oil blends
comprising xxxxxx.
[0041] Base Oil Component: In one embodiment, the base oil or blend
thereof comprises at least an isomerized base oil which the product
itself, its fraction, or feed originates from or is produced at
some stage by isomerization of a waxy feed from a Fischer-Tropsch
process ("Fischer-Tropsch derived base oils"). In another
embodiment, the base oil comprises at least an isomerized base oil
made from a substantially paraffinic wax feed ("waxy feed"). In a
third embodiment, the isomerized base oil comprises mixtures of
products made from a substantially paraffinic wax feed as well as
products made from a waxy feed from a Fischer-Tropsch process.
[0042] Fischer-Tropsch derived base oils are disclosed in a number
of patent publications, including for example U.S. Pat. Nos.
6,080,301, 6,090,989, and 6,165,949, and US Patent Publication No.
US2004/0079678A1, US20050133409, US20060289337. The Fischer-Tropsch
process is a catalyzed chemical reaction in which carbon monoxide
and hydrogen are converted into liquid hydrocarbons of various
forms including a light reaction product and a waxy reaction
product, with both being substantially paraffinic.
[0043] In one embodiment the isomerized base oil has consecutive
numbers of carbon atoms and has less than 25 wt % naphthenic carbon
by n-d-M with normalization. In another embodiment, the amount of
naphthenic carbon is less than 10 wt. %. In yet another embodiment
the isomerized base oil made from a waxy feed has a kinematic
viscosity at 100.degree. C. between 1.5 and 3.5 mm.sup.2/s.
[0044] In one embodiment, the isomerized base oil is made by a
process in which the hydroisomerization dewaxing is performed at
conditions sufficient for the base oil to have: a) a weight percent
of all molecules with at least one aromatic functionality less than
0.30; b) a weight percent of all molecules with at least one
cycloparaffinic functionality greater than 10; c) a ratio of weight
percent molecules with monocycloparaffinic functionality to weight
percent molecules with multicycloparaffinic functionality greater
than 20 and d) a viscosity index greater than 28.times.Ln
(Kinematic viscosity at 100.degree. C.)+80.
[0045] In another embodiment, the isomerized base oil is made from
a process in which the highly paraffinic wax is hydroisomerized
using a shape selective intermediate pore size molecular sieve
comprising a noble metal hydrogenation component, and under
conditions of 600-750.degree. F. (315-399.degree. C.) In the
process, the conditions for hydroisomerization are controlled such
that the conversion of the compounds boiling above 700.degree. F.
(371.degree. C.) in the wax feed to compounds boiling below
700.degree. F. (371.degree. C.) is maintained between 10 wt % and
50 wt %. A resulting isomerized base oil has a kinematic viscosity
of between 1.0 and 3.5 mm.sup.2/s at 100.degree. C. and a Noack
volatility of less than 50 weight %. The base oil comprises greater
than 3 weight % molecules with cycloparaffinic functionality and
less than 0.30 weight percent aromatics.
[0046] In one embodiment the isomerized base oil has a Noack
volatility less than an amount calculated by the following
equation: 1000.times.(Kinematic Viscosity at 100.degree.
C.).sup.-2.7. In another embodiment, the isomerized base oil has a
Noack volatility less than an amount calculated by the following
equation: 900.times.(Kinematic Vicosity at 100.degree.
C.).sup.-2.8. In a third embodiment, the isomerized base oil has a
Kinematic Viscosity at 100.degree. C. of >1.808 mm.sup.2/s and a
Noack volatility less than an amount calculated by the following
equation: 1.286+20 (kV100).sup.-1.5+551.8 e.sup.-kv100, where kv100
is the kinematic viscosity at 100.degree. C. In a fourth
embodiment, the isomerized base oil has a kinematic viscosity at
100.degree. C. of less than 4.0 mm.sup.2/s, and a wt % Noack
volatility between 0 and 100. In a fifth embodiment, the isomerized
base oil has a kinematic viscosity between 1.5 and 4.0 mm.sup.2/s
and a Noack volatility less than the Noack volatility calculated by
the following equation: 160-40 (Kinematic Viscosity at 100.degree.
C.).
[0047] In one embodiment, the isomerized base oil has a kinematic
viscosity at 100.degree. C. in the range of 2.4 and 3.8 mm.sup.2/s
and a Noack volatility less than an amount defined by the equation:
900.times.(Kinematic Viscosity at 100.degree. C.).sup.-2.8-15). For
kinematic viscosities in the range of 2.4 and 3.8 mm.sup.2/s, the
equation: 900.times.(Kinematic Viscosity at 100.degree.
C.).sup.-2.8-15) provides a lower Noack volatility than the
equation: 160-40 (Kinematic Viscosity at 100.degree. C.)
[0048] In one embodiment, the isomerized base oil is made from a
process in which the highly paraffinic wax is hydroisomerized under
conditions for the base oil to have a kinematic viscosity at
100.degree. C. of 3.6 to 4.2 mm.sup.2/s, a viscosity index of
greater than 130, a wt % Noack volatility less than 12, a pour
point of less than -9.degree. C.
[0049] In one embodiment, the isomerized base oil has an aniline
point, in degrees F, greater than 200 and less than or equal to an
amount defined by the equation: 36.times.Ln(Kinematic Viscosity at
100.degree. C., in mm.sup.2/s)+200.
[0050] In one embodiment, the isomerized base oil has an
auto-ignition temperature (AIT) greater than the AIT defined by the
equation: AIT in .degree. C.=1.6.times.(Kinematic Viscosity at
40.degree. C., in mm2/s)+300. In a second embodiment, the base oil
as an AIT of greater than 329.degree. C. and a viscosity index
greater than 28.times.Ln (Kinematic Viscosity at 100.degree. C., in
mm.sup.2/s)+100.
[0051] In one embodiment, the isomerized base oil has a relatively
low traction coefficient, specifically, its traction coefficient is
less than an amount calculated by the equation: traction
coefficient=0.009.times.Ln (kinematic viscosity in
mm.sup.2/s)-0.001, wherein the kinematic viscosity in the equation
is the kinematic viscosity during the traction coefficient
measurement and is between 2 and 50 mm.sup.2/s. In one embodiment,
the isomerized base oil has a traction coefficient of less than
0.023 (or less than 0.021) when measured at a kinematic viscosity
of 15 mm.sup.2/s and at a slide to roll ratio of 40%. In another
embodiment the isomerized base oil has a traction coefficient of
less than 0.017 when measured at a kinematic viscosity of 15
mm.sup.2/s and at a slide to roll ratio of 40%. In another
embodiment the isomerized base oil has a viscosity index greater
than 150 and a traction coefficient less than 0.015 when measured
at a kinematic viscosity of 15 mm.sup.2/s and at a slide to roll
ratio of 40 percent.
[0052] In some embodiments, the isomerized base oil having low
traction coefficients also displays a higher kinematic viscosity
and higher boiling points. In one embodiment, the base oil has a
traction coefficient less than 0.015, and a 50 wt % boiling point
greater than 565.degree. C. (1050.degree. F.). In another
embodiment, the base oil has a traction coefficient less than 0.011
and a 50 wt % boiling point by ASTM D 6352-04 greater than
582.degree. C. (1080.degree. F.).
[0053] In some embodiments, the isomerized base oil having low
traction coefficients also displays unique branching properties by
NMR, including a branching index less than or equal to 23.4, a
branching proximity greater than or equal to 22.0, and a Free
Carbon Index between 9 and 30. In one embodiment, the base oil has
at least 4 wt % naphthenic carbon, in another embodiment, at least
5 wt % naphthenic carbon by n-d-M analysis by ASTM D 3238-95
(Reapproved 2005) with normalization.
[0054] In one embodiment, the isomerized base oil is produced in a
process wherein the intermediate oil isomerate comprises paraffinic
hydrocarbon components, and in which the extent of branching is
less than 7 alkyl branches per 100 carbons, and wherein the base
oil comprises paraffinic hydrocarbon components in which the extent
of branching is less than 8 alkyl branches per 100 carbons and less
than 20 wt % of the alkyl branches are at the 2 position. In one
embodiment, the FT base oil has a pour point of less than
-8.degree. C.; a kinematic viscosity at 100.degree. C. of at least
3.2 mm.sup.2/s; and a viscosity index greater than a viscosity
index calculated by the equation of=22.times.Ln (kinematic
viscosity at 100.degree. C.)+132.
[0055] In one embodiment, the base oil comprises greater than 10
wt. % and less than 70 wt. % total molecules with cycloparaffinic
functionality, and a ratio of weight percent molecules with
monocycloparaffinic functionality to weight percent molecules with
multicycloparaffinic functionality greater than 15.
[0056] In one embodiment, the isomerized base oil has an average
molecular weight between 600 and 1100, and an average degree of
branching in the molecules between 6.5 and 10 alkyl branches per
100 carbon atoms. In another embodiment, the isomerized base oil
has a kinematic viscosity between about 8 and about 25 mm.sup.2/s
and an average degree of branching in the molecules between 6.5 and
10 alkyl branches per 100 carbon atoms.
[0057] In one embodiment, the isomerized base oil is obtained from
a process in which the highly paraffinic wax is hydroisomerized at
a hydrogen to feed ratio from 712.4 to 3562 liter H.sub.2/liter
oil, for the base oil to have a total weight percent of molecules
with cycloparaffinic functionality of greater than 10, and a ratio
of weight percent molecules with monocycloparaffinic functionality
to weight percent molecules with multicycloparaffinic functionality
of greater than 15. In another embodiment, the base oil has a
viscosity index greater than an amount defined by the equation:
28.times.Ln (Kinematic viscosity at 100.degree. C.)+95. In a third
embodiment, the base oil comprises a weight percent aromatics less
than 0.30; a weight percent of molecules with cycloparaffinic
functionality greater than 10; a ratio of weight percent of
molecules with monocycloparaffinic functionality to weight percent
of molecules with multicycloparaffinic functionality greater than
20; and a viscosity index greater than 28.times.Ln (Kinematic
Viscosity at 100.degree. C.)+110. In a fourth embodiment, the base
oil further has a kinematic viscosity at 100.degree. C. greater
than 6 mm.sup.2/s. In a fifth embodiment, the base oil has a weight
percent aromatics less than 0.05 and a viscosity index greater than
28.times.Ln (Kinematic Viscosity at 100.degree. C.)+95. In a sixth
embodiment, the base oil has a weight percent aromatics less than
0.30, a weight percent molecules with cycloparaffinic functionality
greater than the kinematic viscosity at 100.degree. C., in
mm.sup.2/s, multiplied by three, and a ratio of molecules with
monocycloparaffinic functionality to molecules with
multicycloparaffinic functionality greater than 15.
[0058] In one embodiment, the isomerized base oil contains between
2 and 10 wt % naphthenic carbon as measured by n-d-M. In one
embodiment, the base oil has a kinematic viscosity of 1.5-3.0
mm.sup.2/s at 100.degree. C. and 2-3 wt % naphthenic carbon. In
another embodiment, a kinematic viscosity of 1.8-3.5 mm.sup.2/s at
100.degree. C. and 2.5-4 wt % naphthenic carbon. In a third
embodiment, a kinematic viscosity of 3-6 mm.sup.2/s at 100.degree.
C. and 2.7-5 wt % naphthenic carbon. In a fourth embodiment, a
kinematic viscosity of 10-30 mm.sup.2/s at 100.degree. C. and
between greater than 5.2 % and less than 25 wt % naphthenic
carbon.
[0059] In one embodiment, the isomerized base oil has an average
molecular weight greater than 475; a viscosity index greater than
140, and a weight percent olefins less than 10. The base oil
improves the air release and low foaming characteristics of the
mixture when incorporated into the engine oil composition.
[0060] In one embodiment, the isomerized base oil is a FT base oil
having a kinematic viscosity at 100.degree. C. between 3 mm.sup.2/s
and 10 mm.sup.2/s; a viscosity index between 135 and 160; CCS VIS
in the range of 1,000-7,500 mPa.s at -35.degree. C.; pour point in
the range of -20 and -30.degree. C.; Oxidator BN of 35 to 50 hours;
and Noack volatility in wt. % of 2 to 20 as measured by ASTM
D5800-05 Procedure B.
[0061] In one embodiment, the engine oil composition employs a base
oil that consists of at least one of the isomerized base oils
described above. In another embodiment, the composition consists
essentially of at least a Fischer-Tropsch base oil. In yet another
embodiment, the composition employs at least a Fischer-Tropsch base
oil and optionally 5 to 30 wt. % of at least another type of oil,
e.g., lubricant base oils selected from Group I, II, III, IV, and V
lubricant base oils as defined in the API Interchange Guidelines,
and mixtures thereof Examples include conventionally used mineral
oils, synthetic hydrocarbon oils or synthetic ester oils, or
mixtures thereof depending on the application. Mineral lubricating
oil base stocks can be any conventionally refined base stocks
derived from paraffinic, naphthenic and mixed base crudes.
Synthetic lubricating oils that can be used include esters of
glycols and complex esters. Other synthetic oils that can be used
include synthetic hydrocarbons such as polyalphaolefins; alkyl
benzenes, e.g., alkylate bottoms from the alkylation of benzene
with tetrapropylene, or the copolymers of ethylene and propylene;
silicone oils, e.g., ethyl phenyl polysiloxanes, methyl
polysiloxanes, etc., polyglycol oils, e.g., those obtained by
condensing butyl alcohol with propylene oxide; etc. Other suitable
synthetic oils include the polyphenyl ethers, e.g., those having
from 3 to 7 ether linkages and 4 to 8 phenyl groups. Other suitable
synthetic oils include polyisobutenes, and alkylated aromatics such
as alkylated naphthalenes.
[0062] Additional Components: In one embodiment, the engine oil
further comprises at least an additive selected from the group of
metal detergents, dispersants, wear inhibitors, oxidation
inhibitors, friction modifiers, viscosity modifiers, corrosion
inhibitors, seal swelling agents, metal deactivators, antifoamers,
and mixtures thereof, in a sufficient amount to provide the desired
effects. In one embodiment, this sufficient amount is 0.05 to 40
wt. %. In another embodiment, it is between 1 to 35 wt. %. In a
third embodiment, from 5 to 25 wt. %.
[0063] In one embodiment, the additives are incorporated as an
"additive package." As used herein, the term "additive package"
means any combination of additives listed above for engine oil
compositions. In one embodiment, the additive package is a
commercially available package, added in an amount from about 1.5%
to about 30% by weight of the finished composition. In one
embodiment, the additive package is a commercially available
package from the Lubrizol Corporation or from Chevron Oronite
Company LLC.
[0064] Dispersants: Dispersants are generally used to maintain in
suspension insoluble materials resulting from oxidation during use,
thus preventing sludge flocculation and precipitation or deposition
on engine parts. In one embodiment, the composition comprises 0.3
to about 15.0 wt. % of at least a dispersant. In a second
embodiment, from 3.0 to about 7.0 wt. % of at least a dispersant.
Examples of dispersants include nitrogen-containing ashless
(metal-free) dispersants. An ashless dispersant generally comprises
an oil soluble polymeric hydrocarbon backbone having functional
groups that are capable of associating with particles to be
dispersed. Other examples of dispersants include, but are not
limited to, amines, alcohols, amides, or ester polar moieties
attached to the polymer backbones via bridging groups.
[0065] In one embodiment, the engine oil composition comprises an
ashless dispersant selected from oil soluble salts, esters,
amino-esters, amides, imides, and oxazolines of long chain
hydrocarbon substituted mono and dicarboxylic acids or their
anhydrides; thiocarboxylate derivatives of long chain hydrocarbons,
long chain aliphatic hydrocarbons having a polyamine attached
directly thereto; and Mannich condensation products formed by
condensing a long chain substituted phenol with formaldehyde and
polyalkylene polyamine. In another embodiment, the composition
comprises at least a carboxylic dispersant. Carboxylic dispersants
are reaction products of carboxylic acylating agents (acids,
anhydrides, esters, etc.) comprising at least 34 and preferably at
least 54 carbon atoms with nitrogen containing compounds (such as
amines), organic hydroxy compounds (such as aliphatic compounds
including monohydric and polyhydric alcohols, or aromatic compounds
including phenols and naphthols), and/or basic inorganic materials.
These reaction products include imides, amides, and esters, e.g.,
succinimide dispersants.
[0066] Other suitable ashless dispersants may also include amine
dispersants, which are reaction products of relatively high
molecular weight aliphatic halides and amines, preferably
polyalkylene polyamines. Other examples may further include
"Mannich dispersants," which are reaction products of alkyl phenols
in which the alkyl group contains at least 30 carbon atoms with
aldehydes (especially formaldehyde) and amines (especially
polyalkylene polyamines). In other embodiments, suitable ashless
dispersants may even include post-treated dispersants, which are
obtained by reacting carboxylic, amine or Mannich dispersants with
reagents such as dimercaptothiazoles, urea, thiourea, carbon
disulfide, aldehydes, ketones, carboxylic acids,
hydrocarbon-substituted succinic anhydrides, nitrile epoxides,
boron compounds and the like. Suitable ashless dispersants may be
polymeric, which are interpolymers of oil-solubilizing monomers
such as decyl methacrylate, vinyl decyl ether and high molecular
weight olefins with monomers containing polar substitutes.
[0067] In one embodiment, an ethylene carbonate-treated
bissuccinimide derived from a polyisobutylene having a number
average molecular weight of about 2300 Daltons is used as the
ashless dispersant. In yet another embodiment, the engine oil
composition comprises an ethylene-carbonate treated bissuccinimide
dispersant derived from a polyisobutylene succinic anhydride,
wherein the polyisobutylene chain has a number average molecular
weight of about 2300 Daltons ("PIBSA 2300") in an amount of about
6.5 wt. %.
[0068] Viscosity Index Improvers (Modifiers): The viscosity index
of an engine oil base stock can be increased, or improved, by
incorporating therein certain polymeric materials that function as
viscosity modifiers (VM) or viscosity index improvers (VII) in an
amount of 0.3 to 25 wt. %. of the final weight of the engine oil.
Examples include but are not limited to olefin copolymers, such as
ethylene-propylene copolymers, styrene-isoprene copolymers,
hydrated styrene-isoprene copolymers, polybutene, polyisobutylene,
polymethacrylates, vinylpyrrolidone and methacrylate copolymers and
dispersant type viscosity index improvers. These viscosity
modifiers can optionally be grafted with grafting materials such
as, for example, maleic anhydride, and the grafted material can be
reacted with, for example, amines, amides, nitrogen-containing
heterocyclic compounds or alcohol, to form multifunctional
viscosity modifiers (dispersant-viscosity modifiers).
[0069] In one embodiment, the engine oil composition comprises
about 0.3 to 15 wt. % of an ethylene propylene copolymer viscosity
index modifier. Other examples of viscosity modifiers include star
polymers, e.g., a star polymer comprising isoprene/styrene/isoprene
triblock. Yet other examples of viscosity modifiers include poly
alkyl(meth)acrylates of low Brookfield viscosity and high shear
stability, functionalized poly alkyl(meth)acrylates with dispersant
properties of high Brookfield viscosity and high shear stability,
polyisobutylene having a weight average molecular weight ranging
from 700 to 2,500 Daltons and mixtures thereof.
[0070] Friction Modifiers: In one embodiment, the lubricating oil
composition further comprises at least a friction modifier, e.g., a
sulfur-containing molybdenum compound. In some embodiments, the
composition does not contain any friction modifier at all (or just
a minimal amount, e.g., less than 0.1 wt. %) while still providing
excellent fuel economy performance. Certain sulfur-containing
organo-molybdenum compounds are known to modify friction in
lubricating oil compositions, while also offering antioxidant and
antiwear credits. Examples of oil soluble organo-molybdenum
compounds include dithiocarbamates, dithiophosphates,
dithiophosphinates, xanthates, thioxanthates, sulfides, and the
like, and mixtures thereof. In another embodiment, the composition
employs a molybdenum succinimide complex as friction modifier in an
amount of 0.15 to about 1.5 wt. %. In a third embodiment, the
engine oil composition comprises at least a mono-, di- or triester
of a tertiary hydroxyl amine and a fatty acid as a friction
modifying fuel economy additive. In another embodiment, the
friction modifier is selected from the group of succinamic acid,
succinimide, and mixtures thereof. In yet another embodiment, the
friction modifier is selected from an aliphatic fatty amine, an
ether amine, an alkoxylated aliphatic fatty amine, an alkoxylated
ether amine, an oil-soluble aliphatic carboxylic acid, a polyol
ester, a fatty acid amide, an imidazoline, a tertiary amine, a
hydrocarbyl succinic anhydride or acid reacted with an ammonia or a
primary amine, and mixtures thereof.
[0071] Seal swelling agents: Seal fixes are also termed seal
swelling agents or seal pacifiers. They are often employed in
lubricant or additive compositions to insure proper elastomer
sealing, and prevent premature seal failures and leakages. In one
embodiment, the composition further includes at least a seal swell
agent selected from oil-soluble, saturated, aliphatic, or aromatic
hydrocarbon esters such as di-2-ethylhexylphthalate, mineral oils
with aliphatic alcohols such as tridecyl alcohol, triphosphite
ester in combination with a hydrocarbonyl-substituted phenol, and
di-2-ethylhexylsebacate.
[0072] Corrosion inhibitors (Anti-corrosive agents): These
additives are typically added to reduce the degradation of the
metallic parts contained in the engine oil in amounts from about
0.02 to 1 wt. %. Examples include zinc dialkyldithiophosphate,
phosphosulfurized hydrocarbons and the products obtained by
reaction of a phosphosulfurized hydrocarbon with an alkaline earth
metal oxide or hydroxide, preferably in the presence of an
alkylated phenol or of an alkylphenol thioester. In one embodiment,
the rust inhibitor or anticorrosion agents may be a nonionic
polyoxyethylene surface active agent. Nonionic polyoxyethylene
surface active agents include, but are not limited to,
polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether,
polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl
ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl
ether, polyoxyethylene sorbitol monostearate, polyoxyethylene
sorbitol mono-oleate, and polyethylene glycol monooleate. Rust
inhibitors or anticorrosion agents may also be other compounds,
which include, for example, stearic acid and other fatty acids,
dicarboxylic acids, metal soaps, fatty acid amine salts, metal
salts of heavy sulfonic acid, partial carboxylic acid ester of
polyhydric alcohols, and phosphoric esters. In another embodiment,
the rust inhibitor is a calcium stearate salt.
[0073] Detergents: In engine oil compositions, metal-containing or
ash-forming detergents function both as detergents to reduce or
remove deposits and as acid neutralizers or rust inhibitors,
thereby reducing wear and corrosion and extending engine life.
Detergents generally comprise a polar head with long hydrophobic
tail, with the polar head comprising a metal salt of an acid
organic compound.
[0074] In one embodiment, the engine oil composition contains one
or more detergents, which are normally salts, e.g., overbased
salts. Overbased salts, or overbased materials, are single phase,
homogeneous Newtonian systems characterized by a metal content in
excess of that which would be present according to the
stoichiometry of the metal and the particular acidic organic
compound reacted with the metal. In another embodiment, the engine
oil composition comprises at least a carboxylate detergent.
Carboxylate detergents, e.g., salicylates, can be prepared by
reacting an aromatic carboxylic acid with an appropriate metal
compound such as an oxide or hydroxide. In yet another embodiment,
the engine oil composition comprises at least an overbased
detergent. Examples of the overbased detergents include, but are
not limited to calcium sulfonates, calcium phenates, calcium
salicylates, calcium stearates and mixtures thereof. Overbased
detergents may be low overbased (e.g., Total Base Number (TBN)
below about 50). Suitable overbased detergents may alternatively be
high overbased (e.g., TBN above about 150) or medium overbased
(e.g., TBN between 50 and 150). The lubricating oil compositions
may comprise more than one overbased detergents, which may be all
low-TBN detergents, all high-TBN detergents, or a mix of those two
types. Other suitable detergents for the lubricating oil
compositions include "hybrid" detergents such as, for example,
phenate/salicylates, sulfonate/phenates, sulfonate/salicylates,
sulfonates/phenates/salicylates, and the like. In other
embodiments, the composition comprises detergents made from alkyl
benzene and fuming sulfonic acid, phenates (high overbased, medium
overbased, or low overbased), high overbased phenate stearates,
phenolates, salicylates, phosphonates, thiophosphonates,
sulfonates, carboxylates, ionic surfactants and sulfonates and the
like.
[0075] Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or
antioxidants reduce the tendency of mineral oils to deteriorate in
service, which deterioration is evidenced by the products of
oxidation such as sludge, lacquer, and varnish-like deposits on
metal surfaces. In one embodiment, the engine oil composition
contains from about 50 ppm to about 5.00 wt. % of at least an
antioxidant selected from the group of phenolic antioxidants,
aminic antioxidants, or a combination thereof. In other
embodiments, the amount of antioxidants is between 0.10 to 3.00 wt.
%. In yet other embodiments, ranging from about 0.20 to 0.80 wt. %.
An example of an antioxidant used is di-C.sub.8-diphenylamine, in
an amount of about 0.05 to 2.00 wt. % of the total weight of the
oil composition. Other examples of antioxidants include MoS and Mo
oxide compounds.
[0076] Other examples of antioxidants include hindered phenols;
alkaline earth metal salts of alkylphenolthioesters having C.sub.5
to C.sub.12 alkyl side chains; calcium nonylphenol sulphide; oil
soluble phenates and sulfurized phenates; phosphosulfurized or
sulfurized hydrocarbons or esters; phosphorous esters; metal
thiocarbamates; oil soluble copper compounds known in the art;
phenyl naphthyl amines such as phenylene diamine, phenothiazine,
diphenyl amine, diarylamine; phenyl-alphanaphthylamine,
2,2'-diethyl-4,4'-dioctyl diphenylamine,
2,2'diethyl-4-t-octyldiphenylamine; alkaline earth metal salts of
alkylphenol thioesters, having C.sub.5 to C.sub.12 alkyl side
chains, e.g., calcium nonylphenol sulfide, barium t-octylphenol
sulfide, zinc dialkylditbiophosphates, dioctylphenylamine,
phenylalphanaphthylamine and mixtures thereof. Some of these
antioxidants further function as corrosion inhibitors. Other
suitable antioxidants which also function as antiwear agents
include bis alkyl dithiothiadiazoles such as 2,5-bis-octyl
dithiothiadiazole.
[0077] Anti-foamants: In one embodiment, the engine oil further
comprises an anti-foamant (foam inhibitor) in amounts ranging from
about 5 to about 50 ppm. Examples include alkyl methacrylate
polymers, dimethyl silicone polymers, and foam inhibitors of the
polysiloxane type, e.g., silicone oil and polydimethyl siloxane,
for foam control. In another embodiment, the anti-foamant is a
mixture of polydimethyl siloxane and fluorosilicone. In yet another
embodiment, the engine oil further comprises an acrylate polymer
anti-foamant, with a weight ratio of the fluorosilicone antifoamant
to the acrylate anti-foamant ranging from about 3:1 to about 1:4.
In a fourth embodiment, the engine oil comprises an
anti-foam-effective amount of a silicon-containing anti-foamant
such that the total amount of silicon in the engine oil is at least
30 ppm. In yet another embodiment, the silicon-containing antifoam
agent is selected from the group consisting of fluorosilicones,
polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes,
cyclic siloxanes, branched siloxanes, silicone polymers and
copolymers, organo-silicone copolymers, and mixtures thereof.
[0078] Seal swelling agents: Seal fixes are also termed seal
swelling agents or seal pacifiers. They are often employed in
lubricant or additive compositions to insure proper elastomer
sealing, and prevent premature seal failures and leakages. In one
embodiment, the composition further includes at least a seal swell
agent selected from oil-soluble, saturated, aliphatic, or aromatic
hydrocarbon esters such as di-2-ethylhexylphthalate, mineral oils
with aliphatic alcohols such as tridecyl alcohol, triphosphite
ester in combination with a hydrocarbonyl-substituted phenol, and
di-2-ethylhexylsebacate.
[0079] Corrosion inhibitors (Anti-corrosive agents): These
additives are typically added to reduce the degradation of the
metallic parts contained in the engine oil. Examples include zinc
dialkyldithiophosphate, phosphosulfurized hydrocarbons and the
products obtained by reaction of a phosphosulfurized hydrocarbon
with an alkaline earth metal oxide or hydroxide, preferably in the
presence of an alkylated phenol or of an alkylphenol thioester. In
one embodiment, the rust inhibitor or anticorrosion agents may be a
nonionic polyoxyethylene surface active agent. Nonionic
polyoxyethylene surface active agents include, but are not limited
to, polyoxyethylene lauryl ether, polyoxyethylene higher alcohol
ether, polyoxyethylene nonylphenyl ether, polyoxyethylene
octylphenyl ether, polyoxyethylene octyl stearyl ether,
polyoxyethylene oleyl ether, polyoxyethylene sorbitol monostearate,
polyoxyethylene sorbitol mono-oleate, and polyethylene glycol
monooleate. Rust inhibitors or anticorrosion agents may also be
other compounds, which include, for example, stearic acid and other
fatty acids, dicarboxylic acids, metal soaps, fatty acid amine
salts, metal salts of heavy sulfonic acid, partial carboxylic acid
ester of polyhydric alcohols, and phosphoric esters. In another
embodiment, the rust inhibitor is a calcium stearate salt.
[0080] Detergents: In engine oil compositions, metal-containing or
ash-forming detergents function both as detergents to reduce or
remove deposits and as acid neutralizers or rust inhibitors,
thereby reducing wear and corrosion and extending engine life.
Detergents generally comprise a polar head with long hydrophobic
tail, with the polar head comprising a metal salt of an acid
organic compound.
[0081] In one embodiment, the engine oil composition contains one
or more detergents, which are normally salts, e.g., overbased
salts. Overbased salts, or overbased materials, are single phase,
homogeneous Newtonian systems characterized by a metal content in
excess of that which would be present according to the
stoichiometry of the metal and the particular acidic organic
compound reacted with the metal. In another embodiment, the engine
oil composition comprises at least a carboxylate detergent.
Carboxylate detergents, e.g., salicylates, can be prepared by
reacting an aromatic carboxylic acid with an appropriate metal
compound such as an oxide or hydroxide. In yet another embodiment,
the engine oil composition comprises at least an overbased
detergent. Examples of the overbased detergents include, but are
not limited to calcium sulfonates, calcium phenates, calcium
salicylates, calcium stearates and mixtures thereof. Overbased
detergents may be low overbased (e.g., Total Base Number (TBN)
below about 50). Sutiable overbased detergents may alternatively be
high overbased (e.g., TBN above about 150) or medium overbased
(e.g., TBN between 50 and 150). The lubricating oil compositions
may comprise more than one overbased detergents, which may be all
low-TBN detergents, all high-TBN detergents, or a mix of those two
types. Other suitable detergents for the lubricating oil
compositions include "hybrid" detergents such as, for example,
phenate/salicylates, sulfonate/phenates, sulfonate/salicylates,
sulfonates/phenates/salicylates, and the like. In other
embodiments, the composition comprises detergents made from alkyl
benzene and fuming sulfonic acid, phenates (high overbased, medium
overbased, or low overbased), high overbased phenate stearates,
phenolates, salicylates, phosphonates, thiophosphonates,
sulfonates, carboxylates, ionic surfactants and sulfonates and the
like.
[0082] Oxidation Inhibitors/Antioxidants: Oxidation inhibitors or
antioxidants reduce the tendency of mineral oils to deteriorate in
service, which deterioration is evidenced by the products of
oxidation such as sludge, lacquer, and varnish-like deposits on
metal surfaces. In one embodiment, the engine oil composition
contains from about 50 ppm to about 5.00 wt. % of at least an
antioxidant selected from the group of phenolic antioxidants,
aminic antioxidants, or a combination thereof. In other
embodiments, the amount of antioxidants is between 0.10 to 3.00 wt.
%. In yet other embodiments, ranging from about 0.20 to 0.80 wt. %.
An example of an antioxidant used is di-C.sub.8-diphenylamine, in
an amount of about 0.05 to 2.00 wt. % of the total weight of the
oil composition. Other examples of antioxidants include MoS and Mo
oxide compounds.
[0083] In one embodiment, the antioxidant is selected from the
group of hindered phenols; alkaline earth metal salts of
alkylphenolthioesters having C.sub.5 to C.sub.12 alkyl side chains;
calcium nonylphenol sulphide; oil soluble phenates and sulfurized
phenates; phosphosulfurized or sulfurized hydrocarbons or esters;
phosphorous esters; metal thiocarbamates; oil soluble copper
compounds known in the art; phenyl naphthyl amines such as
phenylene diamine, phenothiazine, diphenyl amine, diarylamine;
phenyl-alphanaphthylamine, 2,2'-diethyl-4,4'-dioctyl diphenylamine,
2,2'diethyl-4-t-octyldiphenylamine; alkaline earth metal salts of
alkylphenol thioesters, having C.sub.5 to C.sub.12 alkyl side
chains, e.g., calcium nonylphenol sulfide, barium t-octylphenol
sulfide, zinc dialkylditbiophosphates, dioctylphenylamine,
phenylalphanaphthylamine and mixtures thereof. Some of these
antioxidants further function as corrosion inhibitors. Other
suitable antioxidants which also function as antiwear agents
include bis alkyl dithiothiadiazoles such as 2,5-bis-octyl
dithiothiadiazole.
[0084] Anti-foamants: In one embodiment, the engine oil further
comprises an anti-foamant (foam inhibitor) in amounts ranging from
about 5 to about 50 ppm. Examples include alkyl methacrylate
polymers, dimethyl silicone polymers, and foam inhibitors of the
polysiloxane type, e.g., silicone oil and polydimethyl siloxane,
for foam control. In another embodiment, the anti-foamant is a
mixture of polydimethyl siloxane and fluorosilicone. In yet another
embodiment, the engine oil further comprises an acrylate polymer
anti-foamant, with a weight ratio of the fluorosilicone antifoamant
to the acrylate anti-foamant ranging from about 3:1 to about 1:4.
In a fourth embodiment, the engine oil comprises an
anti-foam-effective amount of a silicon-containing anti-foamant
such that the total amount of silicon in the engine oil is at least
30 ppm. In yet another embodiment, the silicon-containing antifoam
agent is selected from the group consisting of fluorosilicones,
polydimethylsiloxane, phenyl-methyl polysiloxane, linear siloxanes,
cyclic siloxanes, branched siloxanes, silicone polymers and
copolymers, organo-silicone copolymers, and mixtures thereof.
[0085] Anti-wear agents: Anti-wear agents can also be added to the
engine oil composition. In one embodiment, the composition further
comprises at least an anti-wear agent selected from phosphates,
phosphites, carbamates, esters, sulfur containing compounds, and
molybdenum complexes. Other representative of suitable antiwear
agents are zinc dialkyldithiophosphate, zinc diaryldilhiophosphate,
Zn or Mo dithiocarbamates, phosphites, amine phosphates, borated
succinimide, magnesium sulfonate, and mixtures thereof. In one
embodiment, the composition further comprises at least a
dihydrocarbyl dithiophosphate metal as antiwear and antioxidant
agent in amounts of about 0.1 to about 10 wt. %, The metal may be
an alkali or alkaline earth metal, or aluminum, lead, tin,
molybdenum, manganese, nickel or copper.
[0086] Extreme Pressure Agents: In one embodiment, the engine oil
composition further comprises an extreme pressure agent. Examples
include alkaline earth metal borated extreme pressure agents and
alkali metal borated extreme pressure agents. Other examples
include sulfurized olefins, zinc dialky-1-dithiophosphate (primary
alkyl, secondary alkyl, and aryl type), di-phenyl sulfide, methyl
tri-chlorostearate, chlorinated naphthalene,
fluoroalkylpolysiloxane, lead naphthenate, neutralized or partially
neutralized phosphates, di-thiophosphates, and sulfur-free
phosphates.
[0087] Some of the above-mentioned additives can provide a
multiplicity of effects; thus for example, a single additive may
act as a dispersant as well as an oxidation inhibitor. These
multifunctional additives are well known. In one embodiment, when
the engine oil composition contains one or more of the
above-mentioned additives, each additive is typically blended into
the base oil in an amount that enables the additive to provide its
desired function. It may be desirable, although not essential, to
prepare one or more additive concentrates comprising additives
(concentrates sometimes being referred to as "additive packages")
whereby several additives can be added simultaneously to the oil to
form the end oil composition. The final composition may employ from
about 0.5 to about 30 wt. % of the concentrate, the remainder being
the oil of lubricating viscosity. The components can be blended in
any order and can be blended as combinations of components.
[0088] Method for Making: The Pour Point Reducing Blend Component
and other additives can be blended into the base oil matrix
individually or in various sub-combinations. In one embodiment, all
of the components are blended concurrently as an additive
concentrate, or additives plus a diluent, such as a hydrocarbon
solvent. The use of an additive concentrate takes advantage of the
mutual compatibility afforded by the combination of ingredients
when in the form of an additive concentrate. In another embodiment,
the engine oil composition is prepared by mixing the base oil and
the pour point depressant with the separate additives or additive
package(s) at an appropriate temperature, e.g., 60.degree. C.,
until homogeneous.
[0089] Applications: Among other things, the engine oil composition
resists viscosity shear and is formulated with a lower level of
viscosity modifiers for excellent protection of gears, bearings,
cam lobes, cam followers, and other high-pressure components in
engines and transmissions.
[0090] The composition delivers lubrication in all types of
automotive and commercial vehicles gasoline and diesel engines,
gasoline fueled four-stroke outboard, inboard, inboard/outboard
(lPO) and personal watercraft motors, including but not limited to
large and small gasoline or diesel engines in cars, motorcycles,
trucks, motor homes, maintenance equipment, heavy equipment, street
rods, military, and marine applications.
[0091] Properties: In one embodiment, the engine oil composition is
characterized as meeting at least one of International Lubricant
Standardization and Approval Committee (ILSAC) GF-4, American
Petroleum Institute (API) CI-4, API CJ4 performance specifications.
In one embodiment, the engine oil composition meets both ILSAC GF-4
and API CI-4 specifications. In another embodiment, the engine oil
composition meets or exceeds European ACEA: A1, A5, B1, B5, ACEA
C1, ACEA C2, ACEA C3, ACEA C4A, and JASO DL-1, and all ILSAC GF-4
for API Certified Gasoline Engine Oils and meets Energy Conserving
Standards. In yet another embodiment, the engine oil composition
meets the specifications for SAE J300 viscosity grade 0W-XX, 5W-XX,
10W-XX, 15W-XX, 20W-XX, or 25W-XX engine oil, wherein XX represents
the integer 20, 30, 40, 50 or 60.
[0092] In one embodiment, the engine oil composition is
characterized as meeting the requirements of SAE J300 over a wide
temperature range while still having a low level of viscosity
modifiers (viscosity index improvers or VII). Depending on the
diluted factor of the viscosity modifiers used, this amount may
range from 0.3 to 25 wt. %. In one embodiment, the reduced amount
of viscosity modifiers is less than 10 wt. %.
[0093] In one embodiment, the engine oil composition has a
kinematic viscosity at 100.degree. C. as specified according to SAE
J300 for the applicable grade. In one embodiment, the composition
has a kinematic viscosity at 100.degree. C. between 3.5 and 25
mm.sup.2/s. In a second embodiment, a kinematic viscosity at
100.degree. C. between 8 and 20 mm.sup.2/s.
[0094] Viscometrics is an important lubricant parameter that
governs the successful operation of engine oils. In one embodiment,
the engine oil composition comprising a isomerized base oil has an
apparent viscosity of 60,000 cP or less in MRV test (ASTM
D4684-07@-40.degree. C.).
[0095] In one embodiment, the engine oil composition has a cold
crank simulator viscosity at -35.degree. C. of less than 9000 cP,
and less than 7500 cP in a second embodiment, and less than 6000 cP
in a third embodiment. In one embodiment, the engine oil
composition has a mini rotary viscosity at -30.degree. C. of less
than 60000 cP and a yield stress of less than 35 Pa (as measured
per ASTM D4684-07@-30.degree. C.).
[0096] In one embodiment, the engine oil composition is
characterized as exhibiting excellent fuel economy performance, of
at least 1% compared to an engine oil composition of the prior art,
i.e., engine oil compositions employing non-isomerized base oils.
Fuel economy performance can be measured using the Phase I Sequence
VIB Screener Test, to be described in the Examples section. In
another embodiment, the fuel savings is at least 1.5% compared to
engine oil compositions of the prior art. In a third embodiment,
the fuel savings is at least 1.75%.
EXAMPLES
[0097] The examples are given as non-limitative illustration of
aspects of the invention. The compositions were subject to a number
of tests including the following non-standard tests:
[0098] Phase I Sequence VIB Screener Test: This is an abbreviated
test method of ASTM D6837-06 for measurement of effects of
automotive engine oils on fuel economy. ASTM D6837-06, Standard
Test Method for Measurement of Effects of Automotive Engine Oils on
Fuel Economy of Passenger Cars and Light-Duty Trucks in Sequence
VIB Spark Ignition Engine, is an engine dynamometer test that
measures the ability of a lubricant to improve the fuel economy of
passenger cars and light-duty trucks equipped with a low friction
engine. In the abbreviated test, testing ends after Phase I and
does not proceed to Phase II. As a result, the method by which %
fuel economy improvement (FEI) is calculated is also slightly
different.
[0099] Under ASTM D6837-06, % fuel economy improvement (FEI) is
calculated using weighted results from two baseline calibration
(BC) candidates, one before Phase I and one after Phase II. In the
abbreviated test used herein, 100% of a single baseline candidate
is used in making the % FEI calculation as described on page 9 of
ASTM D6837-06, with higher % FEI values indicating improved fuel
economy. Fuel economy improvement (FEI) at Stage-1,-2 and -3
depends on a friction modifier in the lubricant and FEI at Stage-4
and Stage-5 depends on viscometric properties of the lubricant.
[0100] The calculation of % FEI for each stage is as follows.
First, the brake specific fuel consumption (BSFC) in kg/kW,h for
each stage is calculated by the following formula: (Integrated Fuel
Flow).times.(9549.3)/BSFC (Integrated Load) (Integrated Speed). The
BSFC data for each stage is multiplied by the nominal power and by
the weight factor to arrive at kg of weighted fuel consumed for
each stage. Based on total fuel consumed at Phase I (from stage 1
to 5), % FEI for each stage can be calculated as follows:
((Weighted fuel consumed for each stage in the BC before oil
)-(Weighted fuel consumed for each stage in the test oil))/(total
fuel consumed at Phase I by BC before oil).times.100.
[0101] In the Phase I Sequence VIB Screener Test used herein,
Stage-4 and Stage-5 of are run at more hydrodynamic lubricating
conditions (i.e., thicker oil film), while Stage-1 and Stage-2 are
run closer to boundary lubricating conditions. Under boundary
conditions, fuel economy is more dependent on added friction
modifiers, which is not as important for fuel economy under more
hydrodynamic lubricating conditions.
[0102] Traction Coefficient Test Method: As engine oils with lower
traction coefficients are desirable as they provide improved fuel
economy, some of the examples were subject to the Traction
Coefficient Test Method as described in US Patent Publication No.
20050241990. In this test, Traction data are obtained with an MTM
Traction Measurement System from PCS Instruments, Ltd. The unit is
configured with a polished 19 mm diameter ball (SAE AISI 52100
steel) angled at 220 to a flat 46 mm diameter polished disk (SAE
AISI 52100 steel). Measurements are made at 40.degree. C.,
70.degree. C., 100.degree. C., and 120.degree. C. The steel ball
and disk are driven independently by two motors at an average
rolling speed of 3 Meters/sec and a slide to roll ratio (SRR) of
40% [defined as the difference in sliding speed between the ball
and disk divided by the mean speed of the ball and disk.
SRR=(Speed1-Speed2)/((Speed1+Speed2)-/2)]. The load on the
ball/disk is 20 Newton resulting in an estimated average contact
stress of 0.546 GPa and a maximum contact stress of 0.819.
EXAMPLES
[0103] Two runs with Group-III based engine lubricating oil and
three runs with Fischer-Tropsch derived base oil based engine
lubricating oil were conducted. In the examples, viscosity at
100.degree. C., High-Temperature High-Shear (HTHS) viscosity at
150.degree. C., and Noack volatility were adjusted to the same
level to eliminate any influence from these properties in the
results. All oils were blended as SAE OW-20 to the same Blend
Viscosity of 4.3 mm.sup.2/s at 100.degree. C.
[0104] Unless specified otherwise, the components in the examples
are as follows (and expressed as wt. % in the Tables) with the same
additives/additive package being used for the examples.
[0105] FTBO base oils: are from Chevron Corporation of San Ramon,
Calif. The properties of the FTBO base oils used in the examples
are shown in Table 4. The oils have very low initial boiling
points, excellent volatility, high Oxidator BN values, high total
weight % molecules with cycloparaffinic functionality, and high
ratios of mono- to multi-cycloparaffins.
[0106] Group III base stock: a commercially available base stock
having a kinematic viscosity at 100.degree. C. of 4.307 and a CCS
VIS at -35.degree. C. of 3165 mPas.
[0107] VII is a commercially available viscosity index
improver.
[0108] PPD is a commercially available pour point depressant.
[0109] FM is a commercially available friction modifier.
[0110] Additive Package is a commercially available additive
package.
Examples 1-2
[0111] An embodiment of an engine oil composition containing an
isomerized base oil blend was compared with a formulation
containing a group III base oil of the prior art. The results are
shown in Table 1.
TABLE-US-00001 TABLE 1 Example 1 Comparative Example 2 SAE Grade
0W-20 0W-20 Group-III Base Stock, wt % 81.34 -- Base Oil 1, wt % --
47.18 Base Oil 2, wt % -- 31.46 Additive Package, wt % 10.89 10.89
FM, wt % 1.17 1.17 VII, wt % 6.30 9.00 PPD, wt % 0.30 0.30
Viscosity @ 100.degree. C. (ASTM 8.35 8.55 D445), mm.sup.2/s VI
(ASTM D2270), mm.sup.2/s 167 193 CCS @ -35.degree. C. (ASTM D5293),
5490 2150 mPa HTHS @ 150.degree. C. (ASTM 4683), 2.63 2.66 mPa
Blend Viscosity (KV100, 4.288 3.748 Calculated), mm.sup.2/s Blend
Viscosity (KV40, 19.90 14.87 Calculated), mm.sup.2/s MRV @
-40.degree. C. (ASTM D4684), 20000 7330 mPa Yield Stress No No
Noack Volatility, % 13.6 14.8 Phase I Sequence VIB Screener Test
Results Phase I FEI at each stage Stage-1, % 0.38 0.37 0.46 0.39
0.37 Stage-2, % 0.20 0.18 0.16 0.19 0.22 Stage-3, % 0.25 0.26 0.38
0.26 0.27 Stage-4, % 0.72 0.81 1.01 0.87 0.86 Stage-5, % 0.66 0.73
0.80 0.77 0.77 Phase I Total FEI, % 2.20 2.34 2.81 2.48 2.50 Phase
I Stage-1 + Stage-2 + 0.82 0.80 1.00 0.84 0.87 Stage-3 FEI, % Phase
I Stage-4 + Stage-5 FEI, % 1.38 1.54 1.81 1.64 1.63
[0112] As shown, the engine lubricating oil containing isomerized
base oil(s) of Example 2 produces significantly higher fuel economy
improvement (FEI), especially in hydrodynamic lubrication condition
compared to the Group-III based engine lubricating oils (Example
1), with a statistically significant p-value of Phase I
Stage-4+Stage-5 FEI of 0.044. A p-value close to 0 means the data,
with respect to the specific test, are not the same. A p-value
<0.05 means the data are statistically different, based on a
95.sup.th percentile confidence interval criteria.
[0113] Additionally, total Phase-I FEI in Example 2 was also
significantly higher than that of the prior art engine oil
(statistically significant p-value of the Phase-I total FEI of
0.041). Without wishing to be bound by theory, it is believed that
the slightly lower base oil Blend Viscosity of Example 2
(containing isomerized base oils), as compared to the Group-III
engine oil of the prior art, may have contributed to the especially
good Phase I Stage-4+Stage-5% FEI.
Examples 3-6
[0114] In these examples, friction modifiers were omitted from the
formulations. The results are as indicated in Table 2.
TABLE-US-00002 TABLE 2 Example 4 Example 6 Example 3 Comparative
Example 5 Comparative SAE Grade 0W-20 0W-20 0W-20 0W-20 Group-III
Base Stock, wt % -- 84.21 -- 83.89 Base Oil 3, wt % 76.18 -- 75.79
-- Base Oil 4, wt % 7.53 -- 7.50 -- Additive Package, wt % 8.39
8.39 8.71 8.71 FM x x VII, wt % 7.60 7.10 7.70 7.10 PPD, wt % 0.3
0.3 0.3 0.3 Viscosity @ 100.degree. C. 8.43 8.46 8.54 8.50 (ASTM
D445), mm.sup.2/s Viscosity @ 40.degree. C. (ASTM 42.30 45.45 43.04
45.26 D445), mm.sup.2/s VI (ASTM D2270), mm.sup.2/s 181 165 177 168
CCS @ -35.degree. C. (ASTM 3010 5240 3050 5390 D5293), mPa HTHS @
150.degree. C. (ASTM 2.58 2.60 2.60 2.60 4683), mPa Blend Viscosity
(KV100, 4.313 4.307 4.313 4.307 Calculated), mm.sup.2/s Blend
Viscosity (KV40, 18.91 20.13 18.91 20.13 Calculated), mm.sup.2/s
MRV @ -40.degree. C. (ASTM 8200 22400 8800 28900 D4684), mPa Yield
Stress No No No No Noack Volatility, % 18.91 20.13 18.91 20.13
Phase I Sequence VIB Screener Test Results Phase I Total FEI, %
1.60 1.78 1.76 1.58 1.96 2.11 1.98 1.84 Phase I Stage-1 + Stage-2 +
0.20 0.46 0.53 0.31 0.67 0.80 0.75 0.62 Stage-3 FEI, % Phase I
Stage-4 + Stage-5 1.39 1.33 1.24 1.26 1.29 1.31 1.23 1.22 FEI,
%
[0115] As shown in Table 2 above, Examples 3 and 5 with
compositions containing isomerized base oil(s) show fuel economy
benefits relative to the prior art engine oil in Stage-4+Stage-5 of
Phase I Sequence VIB Screener Tests, regardless of whether or not a
friction modifier (FM) was included. With respect to these
Stage-4+Stage-5 results, the difference was statistically
significant both when FM was included (p-value=0.036) and when FM
was not included (p-value=0.046). Additionally through the Phase I
Sequence VIB Screener Test, engine oil compositions containing
isomerized base oil(s) show fuel economy improvements compared to
the conventional Group III based engine oils.
Examples 7-10
[0116] Engine oil compositions with and without the addition of
friction modifier(s) according to Table 3 were formulated and
subject to the Traction Coefficient Test Method.
TABLE-US-00003 TABLE 3 Example 8 Example 10 Example 7 Comparative
Example 9 Comparative SAE Grade 0W-20 0W-20 0W-20 0W-20 Group-III
Base -- 81.34 -- 83.46 Stock, wt % Base Oil 1, wt % 47.18 -- 48.73
-- Base Oil 2, wt % 31.46 -- 32.48 -- Additive Package, 10.89 10.89
9.49 9.49 wt % FM 1.17 1.17 -- -- VII, wt % 9.00 6.30 9.00 6.75
PPD, wt % 0.30 0.30 0.30 0.30
[0117] Results of tests according to the Traction Coefficient Test
Method are presented in FIGS. 1-4. FIG. 1 compares the Traction
Coefficient versus Disk Speed of Example 7 (with isomerized base
oils) and Comparative Example 8 with a prior art formulation, with
both formulations including a friction modifier. FIG. 3 is a graph
of log.sub.10 Traction Coefficient versus Disk Speed at various
slide to roll ratio (SRR) values for Examples 7 and 8.
[0118] For formulations without the addition of friction modifiers,
FIG. 2 compares the Traction Coefficient versus Disk Speed of
Example 9 (containing isomerized base oils) with Comparative
Example 10, an engine oil with Group III base stock. FIG. 4 is a
graph of log.sub.10 Traction Coefficient versus Disk Speed at
various SRR values for Examples 9 and 10. As shown in the figures,
engine oil compositions comprising isomerized base oils demonstrate
lower traction coefficients, and thus improved economy.
[0119] The properties of the isomerized base oils used in the
examples are presented in Table 4.
TABLE-US-00004 TABLE 4 Base Oil 1 Base Oil 2 Base Oil 3 Base Oil 4
Kinematic Viscosity @ 40.degree. C., mm.sup.2/s 17.74 37.92
Kinematic Viscosity @ 100.degree. C., mm.sup.2/s 3.562 4.039 4.12
7.129 Viscosity Index 146 150 138 153 Cold Crank Viscosity @
-40.degree. C., mPa 1,700 2,450 Cold Crank Viscosity @ -35.degree.
C., mPa 1,167 1,335 1596 6966 Pour Point, .degree. C. -27 -25 -27
-20 Oxidator BN, hrs 37.64 50.43 41.02 42.07 Noack Volatility, wt %
18.69 13.01 10.22 2.49 Wt % Aromatics by HPLC-UV 0.0353 0.0202
<0.001. <0.001 SIMDIST TBP (wt %), .degree. F. 0.5 327 418
732 805 5 609 723 758 836 10 733 741 770 850 20 760 763 784 869 30
776 780 795 884 40 789 796 805 897 50 801 812 813 913 60 814 829
822 930 70 826 847 832 947 80 840 867 843 973 90 855 887 857 1004
95 866 899 867 1033 99.5 893 921 887 1078 T.sub.95-T.sub.5 Boiling
Range Distribution, .degree. F. 257 (143) 176 (98) 109 (61) 197
(109) (.degree. C.) FIMS Alkanes 81.1 78.9 75.3 73.1 1-Unsaturation
17.9 20.3 23.6 26.5 2-Unsaturation 0.8 0.8 0.9 0.2 3-Unsaturation
0.1 0 0.1 0 4-Unsaturation 0 0 0 0 5-Unsaturation 0 0 0 0
6-Unsaturation 0.1 0 0.1 0.2 % Olefins by Proton NMR 0.00 0.00 0.32
1.38 Wt % Molecules with 17.9 20.3 23.3 25.1 Monocycloparaffinic
Functionality Wt % Molecules with 1.0 0.8 1.1 0.4
Multicycloparaffinic Functionality Mono/Multi ratio 18.6 26.0 21.2
62.8 Alkyl Branches/100 Carbons 9.20 9.58 9.42 8.63
[0120] For the purpose of this specification and appended claims,
unless otherwise indicated, all numbers expressing quantities,
percentages or proportions, and other numerical values used in the
specification and claims, are to be understood as being modified in
all instances by the term "about." Accordingly, unless indicated to
the contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties sought to be obtained and/or
the precision of an instrument for measuring the value, thus
including the standard deviation of error for the device or method
being employed to determine the value. The use of the term "or" in
the claims is used to mean "and/or" unless explicitly indicated to
refer to alternatives only or the alternative are mutually
exclusive, although the disclosure supports a definition that
refers to only alternatives and "and/or." The use of the word "a"
or "an" when used in conjunction with the term "comprising" in the
claims and/or the specification may mean "one," but it is also
consistent with the meaning of "one or more," "at least one," and
"one or more than one." Furthermore, all ranges disclosed herein
are inclusive of the endpoints and are independently combinable. In
general, unless otherwise indicated, singular elements may be in
the plural and vice versa with no loss of generality. As used
herein, the term "include" and its grammatical variants are
intended to be non-limiting, such that recitation of items in a
list is not to the exclusion of other like items that can be
substituted or added to the listed items.
[0121] It is contemplated that any aspect of the invention
discussed in the context of one embodiment of the invention may be
implemented or applied with respect to any other embodiment of the
invention. Likewise, any composition of the invention may be the
result or may be used in any method or process of the
invention.
[0122] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to make and use the invention. The patentable
scope is defined by the claims, and may include other examples that
occur to those skilled in the art. Such other examples are intended
to be within the scope of the claims if they have structural
elements that do not differ from the literal language of the
claims, or if they include equivalent structural elements with
insubstantial differences from the literal languages of the claims.
All citations referred herein are expressly incorporated herein by
reference.
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