U.S. patent application number 16/710483 was filed with the patent office on 2020-06-25 for lubricant compositions with improved wear control.
The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Michael L. Alessi, Gary Christensen, Kathleen K. Cooper, Samuel Flores-Torres, David G.L. Holt.
Application Number | 20200199475 16/710483 |
Document ID | / |
Family ID | 69160309 |
Filed Date | 2020-06-25 |
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United States Patent
Application |
20200199475 |
Kind Code |
A1 |
Flores-Torres; Samuel ; et
al. |
June 25, 2020 |
Lubricant Compositions With Improved Wear Control
Abstract
This disclosure provides a method for improving wear control,
while maintaining or improving energy efficiency, in a mechanical
component having sliding or rolling between contacting surfaces.
The method involves using a lubricant composition in the mechanical
component having sliding or rolling between contacting surfaces.
The lubricant composition has a base stock blend as a major
component, and at least one lubricant additive, as a minor
component. The base stock blend has at least one first base stock
having a viscosity from 1 to 50 cSt at 40.degree. C. and at least
one second base stock having viscosity from 100 to 2000 cSt at
40.degree. C. The first base stock is present in an amount greater
than 50 to 95 wt % of the base stock blend, and the second base
stock is present in an amount from 5 to less than 50 wt % of the
base stock blend. The second base stock is miscible with the first
base stock.
Inventors: |
Flores-Torres; Samuel;
(Burlington, NJ) ; Alessi; Michael L.; (Rose
Valley, PA) ; Christensen; Gary; (Wenonah, NJ)
; Holt; David G.L.; (Center Valley, PA) ; Cooper;
Kathleen K.; (South River, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company |
Annandale |
NJ |
US |
|
|
Family ID: |
69160309 |
Appl. No.: |
16/710483 |
Filed: |
December 11, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62781712 |
Dec 19, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2030/58 20200501;
C10M 2205/003 20130101; C10M 107/02 20130101; C10M 107/10 20130101;
C10N 2030/06 20130101; C10M 2205/0285 20130101; C10N 2020/02
20130101; C10N 2040/25 20130101; C10N 2040/04 20130101; C10N
2030/02 20130101; C10N 2070/00 20130101; C10M 2205/0285 20130101;
C10M 2205/0285 20130101 |
International
Class: |
C10M 107/02 20060101
C10M107/02 |
Claims
1. A method for improving wear control, while maintaining or
improving energy efficiency, in a mechanical component having
sliding or rolling between contacting surfaces, said method
comprising using a lubricant composition in the mechanical
component having sliding or rolling between contacting surfaces,
the lubricant composition comprising a base stock blend as a major
component, and at least one lubricant additive, as a minor
component; wherein the base stock blend comprises at least one
first base stock having a viscosity from 1 cSt to 50 cSt at
40.degree. C. as determined by ASTM D-445, and at least one second
base stock having viscosity from 100 cSt to 2000 cSt at 40.degree.
C. as determined by ASTM D-445; wherein the first base stock is
present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend; and
wherein the second base stock is miscible with the first base
stock.
2. The method of claim 1 wherein, in the mechanical component
having sliding or rolling between contacting surfaces lubricated
with the lubricant composition, traction coefficient (Tc) is
controlled by concentration of the first base stock, and film
thickness is controlled by the concentration of the second base
stock.
3. The method of claim 1 wherein the first base stock is present in
an amount from 60 to 95 weight percent of the base stock blend, and
the second base stock is present in an amount from 5 to 40 weight
percent of the base stock blend.
4. The method of claim 1 wherein the first base stock comprises a
Group I, Group II, Group III, Group IV or Group V base oil, and the
second base stock comprises a Group I, Group II, Group III, Group
IV or Group V base oil.
5. The method of claim 1 wherein the first base stock comprises a
polyalphaolefin (PAO) base oil, and the second base stock comprises
a polyalphaolefin (PAO) base oil or a metallocene catalyzed
polyalphaolefin (PAO) base oil.
6. The method of claim 1 wherein the base stock blend is present in
an amount from 70 to 95 weight percent of the lubricant
composition.
7. The method of claim 1 wherein the first base stock has a
traction coefficient (Tc) of from 0.008 to 0.015 as determined by
MTM TC Method, the second base stock has a traction coefficient
(Tc) of from 0.008 to 0.025 as determined by MTM TC Method, and the
lubricant composition has a traction coefficient (Tc) of less than
0.15 as determined by MTM TC Method.
8. The method of claim 1 wherein the lubricant composition further
comprises one or more of a viscosity modifier, dispersant,
detergent, antioxidant, pour point depressant, corrosion inhibitor,
metal deactivator, seal compatibility additive, anti-foam agent,
inhibitor, and anti-rust additive.
9. The method of claim 1 wherein traction coefficient (Tc) is
independent of viscosity of the lubricant composition.
10. The method of claim 1 wherein the base stock blend is a bimodal
blend.
11. The method of claim 1 wherein, in the mechanical component
having sliding or rolling between contacting surfaces lubricated
with the lubricant composition, a phase separation or transition is
induced in a mechanical contact zone.
12. The method of claim 1 wherein the lubricant composition is a
finished gear, transmission, engine or industrial lubricant.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/781,712, filed on Dec. 19, 2018, the entire
contents of which is incorporated herein by reference.
FIELD
[0002] This disclosure relates to lubricating fluids and oil
formulations which provide improved wear control. In particular,
this disclosure relates to lubricant compositions, methods for
improving wear control, while maintaining or improving energy
efficiency, in a mechanical component having sliding or rolling
between contacting surfaces, methods for controlling traction
coefficient (Tc) of lubricant compositions, and methods for
controlling film thickness of lubricant compositions. The lubricant
compositions of this disclosure are useful as finished gear,
transmission, engine or industrial lubricants.
BACKGROUND
[0003] Environmental regulations and increased energy cost have
made improvement of energy efficiency one of the most prominent
trends among equipment builders and end users of industrial and
mobile equipment. Energy efficiency improvements come from
modifications in mechanical design, use of advanced materials and
changes in the way equipment is operated. Innovative solutions also
come from the lubricant industry, as many of the energy loss
mechanisms are related to lubrication.
[0004] One of the most prominent functions of a lubricant is
keeping the moving mechanical parts apart. Full separation under
load leads to a situation called elastohydrodynamic lubrication
(EHL).
[0005] EHL is the mode of lubrication that exists in non-conforming
concentrated contacts. Examples include the contact between meshing
gear teeth used in hypoid axles, worm gears, etc. and between the
components in a rolling element bearing. In these contacts the load
is supported over a very small contact area which results in very
high contact pressures. As lubricants are drawn into the contact
zone by the movement of the component surfaces, the lubricant
experiences an increase in pressure. Pressures on the order of 1
GPa and above are common in EHL contacts. Most lubricating oils
exhibit a large increase in viscosity in response to higher
pressures. It is this characteristic that results in the separation
of the two surfaces in the contact zone.
[0006] If there is relative sliding between the two contacting
surfaces in the central contact region, the lubricant is sheared
under these high-pressure conditions. The shearing losses depend on
how the oil behaves under these extreme conditions. The properties
of the oil under high pressure, in turn, depend on the type of base
stocks used in the manufacture of the finished lubricant. The
generation of the EHL film is governed by what happens in the inlet
region of the contact; however, the energy losses are governed by
what happens when the lubricant is sheared in the high-pressure
central contact region.
[0007] The resistance of the lubricant to the shearing effects
within an EHL contact is referred to as traction. Even though
ultimately this force would be classified as friction, the distinct
name allows tribologists and lubrication engineers to distinguish
it from friction due to surface interactions. The traction response
is dominated by the behavior of the lubricant under shear in the
central high contact pressure region of an EHL contact. The
traction properties generally depend on the base stock type.
[0008] Traction coefficients can be defined as the traction force
divided by the normal force. The traction force is the force
transmitted across a sheared EHL film. The normal force or contact
load is the force of one element (such as a roller) pushing down on
a second element. Therefore, the traction coefficient is a
non-dimensional measure of the shear resistance imparted by a
lubricant under EHL conditions. Lower traction coefficients result
in lower shearing forces and hence less energy loss if the two
surfaces are in relative motion. Low traction is believed to be
related to improved fuel economy, increased energy efficiency,
reduced operating temperatures, and improved durability. In certain
applications where energy loss is dominated by shearing of a
lubricant (such as worm gearbox), energy efficiency directly
correlates with the traction coefficient.
[0009] This direct correlation makes traction coefficient very
useful for lubricant formulators. Traction is usually measured in a
ball-on-disc machine (e.g. MTM) and has been targeted in lubricant
development helping advance synthetic base stocks (PAOs, synthetic
esters and PAGs) and develop technologies such as extreme modal
blending. In a family of fluids with similar chemical composition,
traction tends to correlate with viscosity. Lubricating products
are sold at a given viscosity point (called a grade). Typically
traction increases with viscosity. It has been shown that traction
of a blend can be minimized by blending base stocks with different
viscosities. Traction coefficient of a blend can be lower than
traction predicted as a linear combination of traction coefficient
of straight base stocks with corresponding viscosity. It is
however, higher than the traction coefficients of its components.
When taken to its extreme this approach uses base stocks with
highest and lowest practical viscosities and is called extreme
modal blending.
[0010] There is a need for lubricating base stocks and additives
capable of improving wear control while maintaining or improving
energy efficiency, particularly in industrial and automotive
applications.
[0011] The present disclosure also provides many additional
advantages, which shall become apparent as described below.
SUMMARY
[0012] This disclosure relates to lubricating fluids and oil
formulations which provide improved wear control. In particular,
this disclosure relates to lubricant compositions, methods for
improving wear control, while maintaining or improving energy
efficiency, in a mechanical component having sliding or rolling
between contacting surfaces, methods for controlling traction
coefficient (Tc) of lubricant compositions, and methods for
controlling film thickness of lubricant compositions. The lubricant
compositions of this disclosure are useful as finished gear,
transmission, engine or industrial lubricants.
[0013] This disclosure also relates in part to a method for
improving wear control, while maintaining or improving energy
efficiency, in a mechanical component having sliding or rolling
between contacting surfaces. The method involves using a lubricant
composition in the mechanical component having sliding or rolling
between contacting surfaces. The lubricant composition has a base
stock blend as a major component, and at least one lubricant
additive, as a minor component. The base stock blend has at least
one first base stock having a viscosity from about 1 cSt to about
50 cSt at 40.degree. C. as determined by ASTM D-445, and at least
one second base stock having viscosity from about 100 cSt to about
2000 cSt at 40.degree. C. as determined by ASTM D-445. The first
base stock is present in an amount greater than about 50 to about
95 weight percent of the base stock blend, and the second base
stock is present in an amount from about 5 to less than about 50
weight percent of the base stock blend. The second base stock is
miscible with the first base stock.
[0014] This disclosure further relates in part to a lubricant
composition having a base stock blend as a major component, and at
least one lubricant additive, as a minor component. The base stock
blend has at least one first base stock having a viscosity from
about 1 cSt to about 50 cSt at 40.degree. C. as determined by ASTM
D-445, and at least one second base stock having viscosity from
about 100 cSt to about 2000 cSt at 40.degree. C. as determined by
ASTM D-445. The first base stock is present in an amount greater
than about 50 to about 95 weight percent of the base stock blend,
and the second base stock is present in an amount from about 5 to
less than about 50 weight percent of the base stock blend. The
second base stock is miscible with the first base stock.
[0015] This disclosure yet further relates in part to a method for
controlling traction coefficient (Tc) of a lubricant composition.
The method involves blending at least one first base stock with at
least one second base stock to give a base stock blend. The first
base stock has a viscosity from about 1 cSt to about 50 cSt at
40.degree. C. as determined by ASTM D-445, and the second base
stock has a viscosity from about 100 cSt to about 2000 cSt at
40.degree. C. as determined by ASTM D-445. The first base stock is
miscible with the second base stock. The first base stock is
present in the base stock blend in an amount sufficient to control
traction coefficient (Tc) of the lubricant composition.
[0016] This disclosure also relates in part to a method for
controlling film thickness of a lubricant composition. The method
involves blending at least one first base stock with at least one
second base stock to give a base stock blend. The first base stock
has a viscosity from about 1 cSt to about 50 cSt at 40.degree. C.
as determined by ASTM D-445, and the second base stock has a
viscosity from about 100 cSt to about 2000 cSt at 40.degree. C. as
determined by ASTM D-445. The second base stock is miscible with
the first base stock. The second base stock is present in the base
stock blend in an amount sufficient to control film thickness of
the lubricant composition.
[0017] This disclosure further relates in part to a method for
improving wear control, while maintaining or improving energy
efficiency, in a mechanical component having sliding or rolling
between contacting surfaces. The method comprises using a lubricant
composition in the mechanical component having sliding or rolling
between contacting surfaces. The lubricant composition comprises a
base stock blend as a major component, and at least one lubricant
additive, as a minor component. The base stock blend comprises at
least one first base stock having a viscosity from about 1 cSt to
about 50 cSt at 40.degree. C. as determined by ASTM D-445, and at
least one second base stock having viscosity from about 1 cSt to
about 50 cSt at 40.degree. C. as determined by ASTM D-445. The
first base stock is different from the second base stock. The first
base stock is present in an amount greater than about 50 to about
95 weight percent of the base stock blend, and the second base
stock is present in an amount from about 5 to less than about 50
weight percent of the base stock blend. The second base stock is
miscible with the first base stock.
[0018] This disclosure yet further relates in part to a lubricant
composition comprising a base stock blend as a major component, and
at least one lubricant additive, as a minor component. The base
stock blend comprises at least one first base stock having a
viscosity from about 1 cSt to about 50 cSt at 40.degree. C. as
determined by ASTM D-445, and at least one second base stock having
viscosity from about 1 cSt to about 50 cSt at 40.degree. C. as
determined by ASTM D-445. The first base stock is different from
the second base stock. The first base stock is present in an amount
greater than about 50 to about 95 weight percent of the base stock
blend, and the second base stock is present in an amount from about
5 to less than about 50 weight percent of the base stock blend. The
second base stock is miscible with the first base stock.
[0019] It has been surprisingly found that, in a lubricant
composition having a unique base stock blend of a low viscosity
base stock and a high viscosity base stock, the traction
coefficient is dependent on the concentration of the low viscosity
base stock, and independent of lubricant composition viscosity. The
unique base stock blend has at least one first base stock having a
viscosity from about 1 cSt to about 50 cSt at 40.degree. C. as
determined by ASTM D-445, and at least one second base stock having
viscosity from about 100 cSt to about 2000 cSt at 40.degree. C. as
determined by ASTM D-445. The first base stock and second base
stock are miscible with each other. The first base stock is present
in an amount greater than about 50 to about 95 weight percent of
the base stock blend, and the second base stock is present in an
amount from about 5 to less than about 50 weight percent of the
base stock blend.
[0020] Also, it has been surprisingly found that, in a mechanical
component having sliding or rolling between contacting surfaces
lubricated with a lubricant composition having a unique base stock
blend of a low viscosity base stock and a high viscosity base
stock, traction coefficient (Tc) is controlled by concentration of
the first base stock, and film thickness is controlled by the
concentration of the second base stock. The unique base stock blend
has at least one first base stock having a viscosity from about 1
cSt to about 50 cSt at 40.degree. C. as determined by ASTM D-445,
and at least one second base stock having viscosity from about 100
cSt to about 2000 cSt at 40.degree. C. as determined by ASTM D-445.
The first base stock and second base stock are miscible with each
other. The first base stock is present in an amount greater than
about 50 to about 95 weight percent of the base stock blend, and
the second base stock is present in an amount from about 5 to less
than about 50 weight percent of the base stock blend.
[0021] Other objects and advantages of the present disclosure will
become apparent from the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 graphically shows traction performance for neat base
oils, PAO 4, PAO 8, PAO 40, PAO 100, mPAO 150, mPAO 300, and mPAO
600, in accordance with the Examples.
[0023] FIG. 2 graphically shows traction performance for blends
made with constant high viscosity base oil (mPAO 150) and varied
low viscosity base oil (i.e., PAO 2, PAO 4, PAO 6 or PAO 8) under
conditions 1 GPa, 25% SRR at 100.degree. C., in accordance with the
Examples.
[0024] FIG. 3 graphically shows traction performance for blends of
multiple high molecular weight PAO polymers (PAO 100, mPAO 150,
mPAO 300, mPAO 600, mPAO 1000) with PAO 4, in accordance with the
Examples.
[0025] FIG. 4 graphically shows traction performance for PAO
bimodal blends made by mixing high viscosity base oil (i.e., PAO
40, PAO 100, mPAO 150, mPAO 300, mPAO 600 or mPAO 1000) with a low
viscosity base oil PAO 4 under conditions 1 GPa, 25% SRR at
100.degree. C., in accordance with the Examples.
[0026] FIG. 5 graphically shows that traction coefficient is
controlled by the low viscosity component of bimodal blends and is
independent of finish oil viscosity, in accordance with the
Examples.
[0027] FIG. 6 graphically shows that, at a low concentration of
high viscosity base oils, the traction increased unexpectedly as
the concentration of PAO 4 increased (viscosity decreasing), in
accordance with the Examples.
[0028] FIG. 7 shows an illustrative mechanical contact zone.
[0029] FIG. 8 shows gears, bearings and other high load/high
pressure applications that rely on elastohydrodynamic (EHD)
lubrication (EHL) to maintain effective separation between moving
parts in equipment leading to reduced friction and enhanced
durability.
DETAILED DESCRIPTION
Definitions
[0030] "About" or "approximately." All numerical values within the
detailed description and the claims herein are modified by "about"
or "approximately" the indicated value, and take into account
experimental error and variations that would be expected by a
person having ordinary skill in the art.
[0031] "Major amount" as it relates to components included within
the lubricating oils of the specification and the claims means
greater than or equal to 50 wt. %, or greater than or equal to 60
wt. %, or greater than or equal to 70 wt. %, or greater than or
equal to 80 wt. %, or greater than or equal to 90 wt. % based on
the total weight of the lubricating oil.
[0032] "Minor amount" as it relates to components included within
the lubricating oils of the specification and the claims means less
than 50 wt. %, or less than or equal to 40 wt. %, or less than or
equal to 30 wt. %, or greater than or equal to 20 wt. %, or less
than or equal to 10 wt. %, or less than or equal to 5 wt. %, or
less than or equal to 2 wt. %, or less than or equal to 1 wt. %,
based on the total weight of the lubricating oil.
[0033] "Essentially free" as it relates to components included
within the lubricating oils of the specification and the claims
means that the particular component is at 0 weight % within the
lubricating oil, or alternatively is at impurity type levels within
the lubricating oil (less than 100 ppm, or less than 20 ppm, or
less than 10 ppm, or less than 1 ppm).
[0034] "Other lubricating oil additives" as used in the
specification and the claims means other lubricating oil additives
that are not specifically recited in the particular section of the
specification or the claims. For example, other lubricating oil
additives may include, but are not limited to, antioxidants,
detergents, dispersants, antiwear additives, corrosion inhibitors,
viscosity modifiers, metal passivators, pour point depressants,
seal compatibility agents, antifoam agents, extreme pressure
agents, friction modifiers and combinations thereof.
[0035] "Other mechanical component" or "mechanical component" as
used in the specification and the claims means an electric vehicle
component, a hybrid vehicle component, a power train, a driveline,
a transmission, a gear, a gear train, a gear set, a compressor, a
pump, a hydraulic system, a bearing, a bushing, a turbine, a
piston, a piston ring, a cylinder liner, a cylinder, a cam, a
tappet, a lifter, a gear, a valve, or a bearing including a
journal, a roller, a tapered, a needle, and a ball bearing.
[0036] "Hydrocarbon" refers to a compound consisting of carbon
atoms and hydrogen atoms.
[0037] "Alkane" refers to a hydrocarbon that is completely
saturated. An alkane can be linear, branched, cyclic, or
substituted cyclic.
[0038] "Olefin" refers to a non-aromatic hydrocarbon comprising one
or more carbon-carbon double bond in the molecular structure
thereof.
[0039] "Mono-olefin" refers to an olefin comprising a single
carbon-carbon double bond.
[0040] "Cn" group or compound refers to a group or a compound
comprising carbon atoms at total number thereof of n. Thus, "Cm-Cn"
group or compound refers to a group or compound comprising carbon
atoms at a total number thereof in the range from m to n. Thus, a
C1-C50 alkyl group refers to an alkyl group comprising carbon atoms
at a total number thereof in the range from 1 to 50.
[0041] "Carbon backbone" refers to the longest straight carbon
chain in the molecule of the compound or the group in question.
"Branch" refer to any substituted or unsubstituted hydrocarbyl
group connected to the carbon backbone. A carbon atom on the carbon
backbone connected to a branch is called a "branched carbon."
[0042] "Epsilon-carbon" in a branched alkane refers to a carbon
atom in its carbon backbone that is (i) connected to two hydrogen
atoms and two carbon atoms and (ii) connected to a branched carbon
via at least four (4) methylene (CH2) groups. Quantity of epsilon
carbon atoms in terms of mole percentage thereof in a alkane
material based on the total moles of carbon atoms can be determined
by using, e.g., .sup.13C NMR.
[0043] "Alpha-carbon" in a branched alkane refers to a carbon atom
in its carbon backbone that is with a methyl end with no branch on
the first 4 carbons. It is also measured in mole percentage using
.sup.13C NMR.
[0044] "T/P methyl" in a branched alkane refers to a methyl end and
a methyl in the 2 position. It is also measured in mole percentage
using .sup.13C NMR.
[0045] "P-methyl" in a branched alkane refers to a methyl branch
anywhere on the chain, except in the 2 position. It is also
measured in mole percentage using .sup.13C NMR.
[0046] "SAE" refers to SAE International, formerly known as Society
of Automotive Engineers, which is a professional organization that
sets standards for internal combustion engine lubricating oils.
[0047] "SAE J300" refers to the viscosity grade classification
system of engine lubricating oils established by SAE, which defines
the limits of the classifications in rheological terms only.
[0048] "Base stock" or "base oil" interchangeably refers to an oil
that can be used as a component of lubricating oils, heat transfer
oils, hydraulic oils, grease products, and the like.
[0049] "Lubricating oil" or "lubricant" interchangeably refers to a
substance that can be introduced between two or more surfaces to
reduce the level of friction between two adjacent surfaces moving
relative to each other. A lubricant base stock is a material,
typically a fluid at various levels of viscosity at the operating
temperature of the lubricant, used to formulate a lubricant by
admixing with other components. Non-limiting examples of base
stocks suitable in lubricants include API Group I, Group II, Group
III, Group IV, and Group V base stocks. PAOs, particularly
hydrogenated PAOs, have recently found wide use in lubricants as a
Group IV base stock, and are particularly preferred. If one base
stock is designated as a primary base stock in the lubricant,
additional base stocks may be called a co-base stock.
[0050] All kinematic viscosity values in this disclosure are as
determined pursuant to ASTM D445. Kinematic viscosity at
100.degree. C. is reported herein as KV100, and kinematic viscosity
at 40.degree. C. is reported herein as KV40. Unit of all KV100 and
KV40 values herein is cSt unless otherwise specified. When
describing the kinematic viscosity at 100.degree. C. is
"essentially" maintained, the kinematic viscosity at 100.degree. C.
is expected to vary less than 0.2 cSt as measured by ASTM D445.
[0051] All viscosity index ("VI") values in this disclosure are as
determined pursuant to ASTM D2270.
[0052] All Noack volatility ("NV") values in this disclosure are as
determined pursuant to ASTM D5800 unless specified otherwise. Unit
of all NV values is wt %, unless otherwise specified.
[0053] All pour point values in this disclosure are as determined
pursuant to ASTM D5950 or D97.
[0054] All CCS viscosity ("CCSV") values in this disclosure are as
determined pursuant to ASTM 5293. Unit of all CCSV values herein is
millipascal second (mPas), which is equivalent to centipoise),
unless specified otherwise. All CCSV values are measured at a
temperature of interest to the lubricating oil formulation or oil
composition in question. Thus, for the purpose of designing and
fabricating engine oil formulations, the temperature of interest is
the temperature at which the SAE J300 imposes a minimal CCSV.
[0055] All percentages in describing chemical compositions herein
are by weight unless specified otherwise. "Wt. %" means percent by
weight.
[0056] Lubricating Oil Compositions of this Disclosure
[0057] Mainly the job of the base oils within lubricants is to
separate the two surfaces via the generation of a lubrication film
between them, preventing metal to metal contact. However, under
extreme conditions, maintaining a uniform lubricant film can be
difficult. Failure to maintain the film can allow metal to metal
contact leading to wear and early failure of the machines. Usually,
additives were used to provide protection when this event occurs.
However, in accordance with this disclosure, it has been found that
the solubility of mixture base oils is another property that can be
used to prevent metal contact and improve life of the
equipment.
[0058] This disclosure relates to a new approach for selecting and
blending base oils and co-base oils that can reduce the probability
of metal to metal contact under mid to extreme lubrication
conditions, thereby increasing durability of equipment and
efficiency. Through proper choice of base oils (e.g., using
solubility parameter as one of the key criteria), wear protection
is improved by inducing a phase transition/separation (e.g. liquid
to liquid, or solid to liquid) in the mechanical contact. In one
embodiment, this transition allows the formulator to use very low
concentrations of a heavy base oil with unexpected film benefits
while maintaining a lower bulk viscosity for better efficiency.
This work has shown that the film thickness (h) is controlled by
very low concentrations of high viscosity base oil while the
traction coefficient (Tc) is controlled by the higher concentration
of low viscosity base oil. This new approach will provide new
technology and formulation design options enabling lubricants with
enhance wear protection and improved efficiency.
[0059] The function of a lubricant is to generate a thin film that
separates a surface from its moving counterpart with the goal of
reducing friction and wear at operating conditions. This disclosure
will mitigate wear and frictional losses through the use of
carefully selected base oils that will generate a very high
viscosity film or solid film via phase separation in the contact
zone, thereby improving durability and energy efficiency.
[0060] A major trend is to improve efficiency/fuel economy while
maintaining equipment protection. The challenge is that these
performance attributes respond differently. Good fuel economy
requires lower viscosity lubricants and equipment protection
requires the opposite. This disclosure provides a solution to this
problem by providing a sacrificial solid film in the contact
maintaining or increasing equipment protection while the bulk
viscosity of the lubricant is lower.
[0061] The conventional understanding is that traction is dependent
upon lubricant viscosity. Surprisingly, the results of this
disclosure show that this is not always the case. In accordance
with this disclosure, traction was shown to be dependent upon the
low viscosity fluid concentration, and independent of viscosity of
the final fluid, particularly within the same bimodal blend family
(i.e., PAO). While not wishing to be bound by any particular
theory, the analysis of traction performance suggests that other
potential mechanisms (e.g., shear thinning, shear or pressure
induced phase transition) may be responsible for the traction
characteristics that these fluids exhibit. Also, in accordance with
this disclosure, characteristics that predominantly control the
properties of the fluids in the contact zone have been identified,
particularly for a selected group of PAO single-component base
fluids and PAO bimodal blends. An illustrative mechanical contact
zone is shown in FIG. 7.
[0062] Gears, bearings and other high load/high pressure
applications rely on elastohydrodynamic (EHD) lubrication (EHL) to
maintain effective separation between moving parts in the equipment
leading to reduced friction and enhanced durability and thus
lifetime of the machines. See FIG. 8. The EHD lubrication film
thickness determines the extent to which opposing surfaces are
separated, and is one of the most important features of an EHD
contact. The EHD film thickness depends on the oil volume entrained
in the inlet, and this is determined by the velocity and rheology
of the lubricant.
[0063] The rheology of the lubricant is controlled by the physical
properties (e.g., temperature, pressure, molecular structure or
composition of the fluid) and the mechanics of the system (e.g.,
geometry, bodies within contact). The EHD contact can be, for
example, a piezoviscous elastic contact. This contact is defined as
a system where there is an elastic deformation effect excerpted by
the pressure on the lubricant (e.g., viscosity increase) and the
solid bodies making the contact (e.g., metal-metal contact), and
this effect cannot be neglected. The pressurized fluid within a
contact is described by the Reynolds equation, and the pressure
profile in the metal surface is described by Hertz equations.
[0064] This is also called a non-conformal contact. See FIG. 8.
This effect is seen under high speed and high load conditions,
e.g., bearing and gears applications. The non-conforming contact
zones, composed of metal-lubricant-metal are under extreme high
pressure, up to 4 GPa. See FIG. 8. Under these high pressure
conditions, the lubricant significantly increases in viscosity and
the slope or profile of viscosity change versus pressure is called
the pressure viscosity coefficient, alpha .alpha..
[0065] The pressure viscosity coefficient, alpha .alpha., value
depends on the chemistry of the fluids as well as the composition
of the blend and is one of the most important parameters that
control film thickness (h) in the contact zone. Furthermore,
conventional understanding is that film thickness is controlled by
viscosity (which varies with temperature and pressure) as well as
operation values such as speed, load, surface geometry, roughness,
and material properties. Surprisingly, in accordance with this
disclosure, film thickness was shown to be dependent upon the high
viscosity fluid concentration, particularly within the same bimodal
blend family (i.e., PAO).
[0066] Friction is present in all moving systems. Friction is
generated due to the resistance of two sliding surfaces. In
accordance with this disclosure, the work in part is with two
surfaces separated by a lubricant in the EHD region, therefore, the
friction observed is coming from the resistance to flow of the
lubricant in the contact area. This friction is often called
traction. The term traction is often used to define fluid
intermolecular friction within the EHD contacts. Traction is the
friction caused by the molecules moving in adjacent shear planes to
each other and traction is defined as the total shear stress over
the entire contact area. As used herein, the traction coefficient
is defined as shear stress divided by the pressure over the whole
contact.
[0067] In the EHD contact (high pressure), the fluid has a
viscosity that is so high that it behaves more like a solid than a
liquid. Consequently, the traction observed is consistent with the
measure of the shearing force of a semi-solidified fluid. These
forces are controlled by the high pressure rheology of the fluid
which are controlled by the intermolecular friction (i.e., the
resistance to flow), which results in generation of heat and loss
of efficiency in the system.
[0068] In accordance with this disclosure, lubricants having base
oil blends are provided that are suitable for use in machines with
various degrees of sliding, i.e., non-conforming concentrated
contacts, such as with roller and spherical bearings, hypoid gears,
worm gears, and also conforming contacts such as thrust and journal
bearings, and the like.
[0069] The disclosure is directed in general to lubricant
compositions having a base stock blend. When used in an engine or
other mechanical component lubricated with the lubricant
composition, film thickness is controlled by the concentration of
one base stock, and traction coefficient (Tc) is controlled by
concentration of another base stock, in the base stock blend. The
lubricant compositions are useful as finished gear, transmission,
engine, and industrial lubricants and in a preferred embodiment are
used as lubricants for non-conforming concentrated contacts with
high sliding such as spur gears, helical gears, hypoid gears, bevel
gears, worm gears and the like.
[0070] In an embodiment, the lubricant compositions have a base
stock blend as a major component, and at least one lubricant
additive, as a minor component. The base stock blend comprises at
least one first base stock having a viscosity from about 1 cSt to
about 50 cSt at 40.degree. C. as determined by ASTM D-445, and at
least one second base stock having viscosity from about 100 cSt to
about 2000 cSt at 40.degree. C. as determined by ASTM D-445. The
first base stock is present in an amount greater than about 50 to
about 95 weight percent of the base stock blend, and the second
base stock is present in an amount from about 5 to less than about
50 weight percent of the base stock blend. The second base stock is
miscible with the first base stock.
[0071] In the base stock blends of this disclosure, the first base
stock has a viscosity from about 1 cSt to about 50 cSt at
40.degree. C., preferably about 1 cSt to about 40 cSt at 40.degree.
C., more preferably about 1.25 cSt to about 30 cSt at 40.degree.
C., and even more preferably about 1.5 cSt to about 20 cSt at
40.degree. C., as determined by ASTM D-445.
[0072] In the base stock blends of this disclosure, the second base
stock has viscosity from about 100 cSt to about 2000 cSt at
40.degree. C., preferably about 100 cSt to about 1800 cSt at
40.degree. C., more preferably about 125 cSt to about 1600 cSt at
40.degree. C., and even more preferably about 150 cSt to about 1500
cSt at 40.degree. C., as determined by ASTM D-445.
[0073] In the base stock blends of this disclosure, the first base
stock is present in an amount greater than about 50 to about 95
weight percent, preferably from about 60 to about 95 weight
percent, more preferably from about 70 to about 95 weight percent,
even more preferably from about 80 to about 95 weight percent, of
the base stock blend. The second base stock is present in an amount
from about 5 to less than about 50 weight percent, preferably from
about 5 to about 40 weight percent, more preferably from about 5 to
about 30 weight percent, even more preferably from about 5 to about
20 weight percent, of the base stock blend. The first and second
base stocks are miscible with each other.
[0074] In the lubricant compositions of this disclosure, the base
stock blend is present in an amount from about 70 to about 95
weight percent, preferably from about 75 to about 95 weight
percent, more preferably from about 80 to about 95 weight percent,
even more preferably from about 85 to about 95 weight percent, of
the lubricant composition.
[0075] In the base stock blends of this disclosure, the first base
stock has a traction coefficient (Tc) from about 0.008 to about
0.015, preferably from about 0.008 to about 0.011, more preferably
from about 0.008 to about 0.01, as determined by MTM TC Method. The
second base stock has a traction coefficient (Tc) from about 0.008
to about 0.025, preferably from about 0.09 to about 0.02, more
preferably from about 0.01 to about 0.02, as determined by MTM TC
Method.
[0076] The lubricant compositions of this disclosure have a
traction coefficient (Tc) of less than 0.15, preferably from about
0.15 to about 0.0001, preferably from about 0.015 to about 0.001,
as determined by MTM TC Method.
[0077] In accordance with this disclosure, traction coefficient
(Tc) is independent of viscosity of the lubricant composition.
[0078] In an embodiment, the base stock blend is a bimodal
blend.
[0079] It is important that the first and second fluids be miscible
with each other to comprise a clear fluid. The term miscible takes
its ordinary meaning of the ability to mix in all proportions. For
purposes of this disclosure, miscibility is determined at
25.degree. C. and 1 atm.
[0080] Fluids (e.g., base stocks) that can meet these criteria
according to the present disclosure are varied. They may fall into
any of the well-known American Petroleum Institute (API) categories
of Group I through Group V as described herein.
[0081] The lubricant compositions of this disclosure may contain
other fluids in addition to the first and second base stocks. For
example, the lubricant compositions may have a third fluid that can
be a high viscosity or low viscosity fluid, or other combinations
of fluids.
[0082] In an embodiment, the first base stock can be selected from
a Group I, Group II, Group III, Group IV or Group V base oil, and
the second base stock can be selected from a Group I, Group II,
Group III, Group IV or Group V base oil. Preferably, the first base
stock can be a polyalphaolefin (PAO) base oil, and the second base
stock can be a polyalphaolefin (PAO) base oil or a metallocene
catalyzed polyalphaolefin (PAO) base oil.
[0083] The lubricant compositions of this disclosure may contain
one or more first base stocks, and/or one or more second base
stocks.
[0084] In an embodiment, the lubricant compositions can further
include one or more of a viscosity modifier, dispersant, detergent,
antioxidant, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, and anti-rust additive.
[0085] Base Stocks
[0086] A wide range of lubricating base oils is known in the art.
Lubricating base oils that are useful in the present disclosure are
both natural oils, and synthetic oils, and unconventional oils (or
mixtures thereof) can be used unrefined, refined, or rerefined (the
latter is also known as reclaimed or reprocessed oil). Unrefined
oils are those obtained directly from a natural or synthetic source
and used without added purification. These include shale oil
obtained directly from retorting operations, petroleum oil obtained
directly from primary distillation, and ester oil obtained directly
from an esterification process. Refined oils are similar to the
oils discussed for unrefined oils except refined oils are subjected
to one or more purification steps to improve at least one
lubricating oil property. One skilled in the art is familiar with
many purification processes. These processes include solvent
extraction, secondary distillation, acid extraction, base
extraction, filtration, and percolation. Rerefined oils are
obtained by processes analogous to refined oils but using an oil
that has been previously used as a feed stock.
[0087] Groups I, II, III, IV and V are broad base oil stock
categories developed and defined by the American Petroleum
Institute (API Publication 1509; www.API.org) to create guidelines
for lubricant base oils. Group I base stocks have a viscosity index
of between about 80 to 120 and contain greater than about 0.03%
sulfur and/or less than about 90% saturates. Group II base stocks
have a viscosity index of between about 80 to 120, and contain less
than or equal to about 0.03% sulfur and greater than or equal to
about 90% saturates. Group III stocks have a viscosity index
greater than about 120 and contain less than or equal to about
0.03% sulfur and greater than about 90% saturates. Group IV
includes polyalphaolefins (PAO). Group V base stock includes base
stocks not included in Groups I-IV. The table below summarizes
properties of each of these five groups.
TABLE-US-00001 Base Oil Properties Saturates Sulfur Viscosity Index
Group I <90 and/or >0.03% and .gtoreq.80 and <120 Group II
.gtoreq.90 and .ltoreq.0.03% and .gtoreq.80 and <120 Group III
.gtoreq.90 and .ltoreq.0.03% and .gtoreq.120 Group IV
Polyalphaolefins (PAO) Group V All other base oil stocks not
included in Groups I, II, III or IV
[0088] Natural oils include animal oils, vegetable oils (castor oil
and lard oil, for example), and mineral oils. Animal and vegetable
oils possessing favorable thermal oxidative stability can be used.
Of the natural oils, mineral oils are preferred. Mineral oils vary
widely as to their crude source, for example, as to whether they
are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils
derived from coal or shale are also useful. Natural oils vary also
as to the method used for their production and purification, for
example, their distillation range and whether they are straight run
or cracked, hydrorefined, or solvent extracted.
[0089] Group II and/or Group III hydroprocessed or hydrocracked
base stocks, including synthetic oils such as polyalphaolefins,
alkyl aromatics and synthetic esters are also well known base stock
oils.
[0090] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
for example). Polyalphaolefin (PAO) oil base stocks are commonly
used synthetic hydrocarbon oil. By way of example, PAOs derived
from C.sub.8, C.sub.10, C.sub.12, C.sub.14 olefins or mixtures
thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064;
and 4,827,073.
[0091] The number average molecular weights of the PAOs, which are
known materials and generally available on a major commercial scale
from suppliers such as ExxonMobil Chemical Company, Chevron
Phillips Chemical Company, BP, and others, typically vary from
about 250 to about 3,000, although PAO's may be made in viscosities
up to about 150 cSt (100.degree. C.). The PAOs are typically
comprised of relatively low molecular weight hydrogenated polymers
or oligomers of alphaolefins which include, but are not limited to,
C.sub.2 to about C.sub.32 alphaolefins with the C.sub.8 to about
C.sub.16 alphaolefins, such as 1-hexene, 1-octene, 1-decene,
1-dodecene and the like, being preferred. The preferred
polyalphaolefins are poly-1-hexene, poly-1-octene, poly-1-decene
and poly-1-dodecene and mixtures thereof and mixed olefin-derived
polyolefins. However, the dimers of higher olefins in the range of
C.sub.14 to C.sub.18 may be used to provide low viscosity base
stocks of acceptably low volatility. Depending on the viscosity
grade and the starting oligomer, the PAOs may be predominantly
trimers and tetramers of the starting olefins, with minor amounts
of the higher oligomers, having a viscosity range of 1.5 to 12 cSt.
PAO fluids of particular use may include 3.0 cSt, 3.4 cSt, and/or
3.6 cSt and combinations thereof. Bi-modal mixtures of PAO fluids
having a viscosity range of 1.5 to 150 cSt may be used if
desired.
[0092] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as the Friedel-Crafts catalysts
including, for example, aluminum trichloride, boron trifluoride or
complexes of boron trifluoride with water, alcohols such as
ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods
disclosed by U.S. Pat. Nos. 4,149,178 or 3,382,291 may be
conveniently used herein. Other descriptions of PAO synthesis are
found in the following U.S. Pat. Nos. 3,742,082; 3,769,363;
3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355;
4,956,122; and 5,068,487. The dimers of the C.sub.14 to C.sub.18
olefins are described in U.S. Pat. No. 4,218,330.
[0093] The alkylated naphthalene can be used as base oil or base
oil component and can be any hydrocarbyl molecule that contains at
least about 5% of its weight derived from a naphthenoid moiety, or
its derivatives. These alkylated naphthalenes include alkyl
naphthalenes, alkyl naphthols, and the like. The naphthenoid group
can be mono-alkylated, dialkylated, polyalkylated, and the like.
The naphthenoid group can be mono- or poly-functionalized. The
naphthenoid group can also be derived from natural (petroleum)
sources, provided at least about 5% of the molecule is comprised of
the naphthenoid moiety. Viscosities at 100.degree. C. of
approximately 3 cSt to about 50 cSt are preferred, with viscosities
of approximately 3.4 cSt to about 20 cSt often being more preferred
for the naphthylene component. In one embodiment, an alkyl
naphthalene where the alkyl group is primarily comprised of
1-hexadecene is used. Other alkylates of naphthalene can be
advantageously used. Naphthalene or methyl naphthalene, for
example, can be alkylated with olefins such as octene, decene,
dodecene, tetradecene or higher, mixtures of similar olefins, and
the like.
[0094] Alkylated naphthalenes of the present disclosure may be
produced by well-known Friedel-Crafts alkylation of aromatic
compounds. See Friedel-Crafts and Related Reactions, Olah, G. A.
(ed.), Inter-science Publishers, New York, 1963. For example, an
aromatic compound, such as naphthalene, is alkylated by an olefin,
alkyl halide or alcohol in the presence of a Friedel-Crafts
catalyst. See Friedel-Crafts and Related Reactions, Vol. 2, part 1,
chapters 14, 17, and 18, See Olah, G. A. (ed.), Inter-science
Publishers, New York, 1964. Many homogeneous or heterogeneous,
solid catalysts are known to one skilled in the art. The choice of
catalyst depends on the reactivity of the starting materials and
product quality requirements. For example, strong acids such as
AlCl.sub.3, BF.sub.3, or HF may be used. In some cases, milder
catalysts such as FeCl.sub.3 or SnCl.sub.4 are preferred. Newer
alkylation technology uses zeolites or solid super acids.
[0095] Mixtures of alkylated naphthalene base stocks with other
lubricating oil base stocks (e.g., Groups I, II, III, IV and V base
stocks) may be useful in the lubricant compositions of this
disclosure.
[0096] The alkylated naphthalene can be present in an amount of
from about 30 to about 99.8 weight percent, or from about 35 to
about 95 weight percent, or from about 40 to about 90 weight
percent, or from about 45 to about 85 weight percent, or from about
50 to about 80 weight percent, or from about 55 to about 75 weight
percent, or from about 60 to about 70 weight percent, based on the
total weight of the formulated oil.
[0097] Other useful lubricant oil base stocks include wax isomerate
base stocks and base oils, comprising hydroisomerized waxy stocks
(e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker
bottoms, etc.), hydroisomerized Fischer-Tropsch waxes,
Gas-to-Liquids (GTL) base stocks and base oils, and other wax
isomerate hydroisomerized base stocks and base oils, or mixtures
thereof Fischer-Tropsch waxes, the high boiling point residues of
Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with
very low sulfur content. The hydroprocessing used for the
production of such base stocks may use an amorphous
hydrocracking/hydroisomerization catalyst, such as one of the
specialized lube hydrocracking (LHDC) catalysts or a crystalline
hydrocracking/hydroisomerization catalyst, preferably a zeolitic
catalyst. For example, one useful catalyst is ZSM-48 as described
in U.S. Pat. No. 5,075,269, the disclosure of which is incorporated
herein by reference in its entirety. Processes for making
hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in
U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as
well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and
1,390,359. Each of the aforementioned patents is incorporated
herein in their entirety. Particularly favorable processes are
described in European Patent Application Nos. 464546 and 464547,
also incorporated herein by reference. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172
and 4,943,672, the disclosures of which are incorporated herein by
reference in their entirety.
[0098] Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived
base oils, and other wax-derived hydroisomerized (wax isomerate)
base oils be advantageously used in the instant disclosure, and may
have useful kinematic viscosities at 100.degree. C. of about 3 cSt
to about 50 cSt, preferably about 3 cSt to about 30 cSt, more
preferably about 3.5 cSt to about 25 cSt, as exemplified by GTL 4
with kinematic viscosity of about 4.0 cSt at 100.degree. C. and a
viscosity index of about 141. These Gas-to-Liquids (GTL) base oils,
Fischer-Tropsch wax derived base oils, and other wax-derived
hydroisomerized base oils may have useful pour points of about
-20.degree. C. or lower, and under some conditions may have
advantageous pour points of about -25.degree. C. or lower, with
useful pour points of about -30.degree. C. to about -40.degree. C.
or lower. Useful compositions of Gas-to-Liquids (GTL) base oils,
Fischer-Tropsch wax derived base oils, and wax-derived
hydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301;
6,090,989, and 6,165,949 for example, and are incorporated herein
in their entirety by reference.
[0099] The hydrocarbyl aromatics can be used as base oil or base
oil component and can be any hydrocarbyl molecule that contains at
least about 5% of its weight derived from an aromatic moiety such
as a benzenoid moiety or naphthenoid moiety, or their derivatives.
These hydrocarbyl aromatics include alkyl benzenes, alkyl
naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl
diphenyl sulfides, alkylated bis-phenol A, alkylated thiodiphenol,
and the like. The aromatic can be mono-alkylated, dialkylated,
polyalkylated, and the like. The aromatic can be mono- or
poly-functionalized. The hydrocarbyl groups can also be comprised
of mixtures of alkyl groups, alkenyl groups, alkynyl, cycloalkyl
groups, cycloalkenyl groups and other related hydrocarbyl groups.
The hydrocarbyl groups can range from about C.sub.6 up to about
C.sub.60 with a range of about C.sub.8 to about C.sub.20 often
being preferred. A mixture of hydrocarbyl groups is often
preferred, and up to about three such substituents may be present.
The hydrocarbyl group can optionally contain sulfur, oxygen, and/or
nitrogen containing substituents. The aromatic group can also be
derived from natural (petroleum) sources, provided at least about
5% of the molecule is comprised of an above-type aromatic moiety.
Viscosities at 100.degree. C. of approximately 3 cSt to about 50
cSt are preferred, with viscosities of approximately 3.4 cSt to
about 20 cSt often being more preferred for the hydrocarbyl
aromatic component. In one embodiment, an alkyl naphthalene where
the alkyl group is primarily comprised of 1-hexadecene is used.
Other alkylates of aromatics can be advantageously used.
Naphthalene or methyl naphthalene, for example, can be alkylated
with olefins such as octene, decene, dodecene, tetradecene or
higher, mixtures of similar olefins, and the like. Useful
concentrations of hydrocarbyl aromatic in a lubricant oil
composition can be about 2% to about 25%, preferably about 4% to
about 20%, and more preferably about 4% to about 15%, depending on
the application.
[0100] Alkylated aromatics such as the hydrocarbyl aromatics of the
present disclosure may be produced by well-known Friedel-Crafts
alkylation of aromatic compounds. See Friedel-Crafts and Related
Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York,
1963. For example, an aromatic compound, such as benzene or
naphthalene, is alkylated by an olefin, alkyl halide or alcohol in
the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and
Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See
Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many
homogeneous or heterogeneous, solid catalysts are known to one
skilled in the art. The choice of catalyst depends on the
reactivity of the starting materials and product quality
requirements. For example, strong acids such as AlCl.sub.3,
BF.sub.3, or HF may be used. In some cases, milder catalysts such
as FeCl.sub.3 or SnCl.sub.4 are preferred. Newer alkylation
technology uses zeolites or solid super acids.
[0101] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of monocarboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0102] Particularly useful synthetic esters are those which are
obtained by reacting one or more polyhydric alcohols, preferably
the hindered polyols (such as the neopentyl polyols, e.g.,
neopentyl glycol, trimethylol ethane,
2-methyl-2-propyl-1,3-propanediol, trimethylol propane,
pentaerythritol and dipentaerythritol) with alkanoic acids
containing at least about 4 carbon atoms, preferably C.sub.5 to
C.sub.30 acids such as saturated straight chain fatty acids
including caprylic acid, capric acid, lauric acid, myristic acid,
palmitic acid, stearic acid, arachic acid, and behenic acid, or the
corresponding branched chain fatty acids or unsaturated fatty acids
such as oleic acid, or mixtures of any of these materials.
[0103] Suitable synthetic ester components include the esters of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more
monocarboxylic acids containing from about 5 to about 10 carbon
atoms. These esters are widely available commercially, for example,
the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.
[0104] Also useful are esters derived from renewable material such
as coconut, palm, rapeseed, soy, sunflower and the like. These
esters may be monoesters, di-esters, polyol esters, complex esters,
or mixtures thereof. These esters are widely available
commercially, for example, the Mobil P-51 ester of ExxonMobil
Chemical Company.
[0105] Engine oil formulations containing renewable esters are
included in this disclosure. For such formulations, the renewable
content of the ester is typically greater than about 70 weight
percent, preferably more than about 80 weight percent and most
preferably more than about 90 weight percent.
[0106] Other useful fluids of lubricating viscosity include
non-conventional or unconventional base stocks that have been
processed, preferably catalytically, or synthesized to provide high
performance lubrication characteristics.
[0107] Non-conventional or unconventional base stocks/base oils
include one or more of a mixture of base stock(s) derived from one
or more Gas-to-Liquids (GTL) materials, as well as
isomerate/isodewaxate base stock(s) derived from natural wax or
waxy feeds, mineral and or non-mineral oil waxy feed stocks such as
slack waxes, natural waxes, and waxy stocks such as gas oils, waxy
fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal
crackates, or other mineral, mineral oil, or even non-petroleum oil
derived waxy materials such as waxy materials received from coal
liquefaction or shale oil, and mixtures of such base stocks.
[0108] GTL materials are materials that are derived via one or more
synthesis, combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds, hydrogen-containing compounds and/or elements as feed
stocks such as hydrogen, carbon dioxide, carbon monoxide, water,
methane, ethane, ethylene, acetylene, propane, propylene, propyne,
butane, butylenes, and butynes. GTL base stocks and/or base oils
are GTL materials of lubricating viscosity that are generally
derived from hydrocarbons; for example, waxy synthesized
hydrocarbons, that are themselves derived from simpler gaseous
carbon-containing compounds, hydrogen-containing compounds and/or
elements as feed stocks. GTL base stock(s) and/or base oil(s)
include oils boiling in the lube oil boiling range (1)
separated/fractionated from synthesized GTL materials such as, for
example, by distillation and subsequently subjected to a final wax
processing step which involves either or both of a catalytic
dewaxing process, or a solvent dewaxing process, to produce lube
oils of reduced/low pour point; (2) synthesized wax isomerates,
comprising, for example, hydrodewaxed or hydroisomerized cat and/or
solvent dewaxed synthesized wax or waxy hydrocarbons; (3)
hydrodewaxed or hydroisomerized cat and/or solvent dewaxed
Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy
hydrocarbons, waxes and possible analogous oxygenates); preferably
hydrodewaxed or hydroisomerized/followed by cat and/or solvent
dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or
hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T
waxes, or mixtures thereof.
[0109] GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially, hydrodewaxed or hydroisomerized/followed by
cat and/or solvent dewaxed wax or waxy feed, preferably F-T
material derived base stock(s) and/or base oil(s), are
characterized typically as having kinematic viscosities at
100.degree. C. of from about 2 mm.sup.2/s to about 50 mm.sup.2/s
(ASTM D445). They are further characterized typically as having
pour points of -5.degree. C. to about -40.degree. C. or lower (ASTM
D97). They are also characterized typically as having viscosity
indices of about 80 to about 140 or greater (ASTM D2270).
[0110] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) typically have very low sulfur and
nitrogen content, generally containing less than about 10 ppm, and
more typically less than about 5 ppm of each of these elements. The
sulfur and nitrogen content of GTL base stock(s) and/or base oil(s)
obtained from F-T material, especially F-T wax, is essentially nil.
In addition, the absence of phosphorous and aromatics make this
materially especially suitable for the formulation of low SAP
products.
[0111] The term GTL base stock and/or base oil and/or wax isomerate
base stock and/or base oil is to be understood as embracing
individual fractions of such materials of wide viscosity range as
recovered in the production process, mixtures of two or more of
such fractions, as well as mixtures of one or two or more low
viscosity fractions with one, two or more higher viscosity
fractions to produce a blend wherein the blend exhibits a target
kinematic viscosity.
[0112] The GTL material, from which the GTL base stock(s) and/or
base oil(s) is/are derived is preferably an F-T material (i.e.,
hydrocarbons, waxy hydrocarbons, wax).
[0113] Base oils for use in the lubricant compositions useful in
the present disclosure are any of the variety of oils corresponding
to API Group I, Group II, Group III, Group IV, and Group V oils and
mixtures thereof, preferably API Group II, Group III, Group IV, and
Group V oils and mixtures thereof, more preferably the Group III to
Group V base oils due to their exceptional volatility, stability,
viscometric and cleanliness features.
[0114] The base oil constitutes the major component of the engine
oil lubricant composition of the present disclosure and typically
is present in an amount ranging from about 50 to about 99 weight
percent, preferably from about 70 to about 95 weight percent, and
more preferably from about 85 to about 95 weight percent, based on
the total weight of the composition. The base oil may be selected
from any of the synthetic or natural oils typically used as
crankcase lubricating oils for spark-ignited and
compression-ignited engines. The base oil conveniently has a
kinematic viscosity, according to ASTM standards, of about 2.5 cSt
to about 12 cSt (or mm.sup.2/s) at 100.degree. C. and preferably of
about 2.5 cSt to about 9 cSt (or mm.sup.2/s) at 100.degree. C.
Mixtures of synthetic and natural base oils may be used if desired.
Bi-modal mixtures of Group I, II, III, IV, and/or V base stocks may
be used if desired.
[0115] Lubricant Add
[0116] The lubricant compositions useful in the present disclosure
may additionally contain one or more of the commonly used lubricant
performance additives including but not limited to antioxidants,
dispersants, detergents, antiwear additives, corrosion inhibitors,
rust inhibitors, metal deactivators, extreme pressure additives,
anti-seizure agents, wax modifiers, viscosity index improvers,
viscosity modifiers, fluid-loss additives, seal compatibility
agents, friction modifiers, lubricity agents, anti-staining agents,
chromophoric agents, defoamants, demulsifiers, emulsifiers,
densifiers, wetting agents, gelling agents, tackiness agents,
colorants, and others. For a review of many commonly used
additives, see Klamann in Lubricants and Related Products, Verlag
Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0. Reference is
also made to "Lubricant Additives" by M. W. Ranney, published by
Noyes Data Corporation of Parkridge, N J (1973); see also U.S. Pat.
No. 7,704,930, the disclosure of which is incorporated herein in
its entirety. These additives are commonly delivered with varying
amounts of diluent oil, that may range from 5 weight percent to 50
weight percent.
[0117] Antioxidants
[0118] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricant compositions. See, Klamann
in Lubricants and Related Products, op cite, and U.S. Pat. Nos.
4,798,684 and 5,084,197, for example.
[0119] Useful antioxidants include hindered phenols. These phenolic
antioxidants may be ashless (metal-free) phenolic compounds or
neutral or basic metal salts of certain phenolic compounds. Typical
phenolic antioxidant compounds are the hindered phenolics which are
the ones which contain a sterically hindered hydroxyl group, and
these include those derivatives of dihydroxy aryl compounds in
which the hydroxyl groups are in the o- or p-position to each
other. Typical phenolic antioxidants include the hindered phenols
substituted with C.sub.6+ alkyl groups and the alkylene coupled
derivatives of these hindered phenols. Examples of phenolic
materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl
phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant disclosure. Examples of ortho-coupled
phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol);
2,2'-bis(4-octyl-6-t-butyl-phenol); and
2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0120] Effective amounts of one or more catalytic antioxidants may
also be used. The catalytic antioxidants comprise an effective
amount of a) one or more oil soluble polymetal organic compounds;
and, effective amounts of b) one or more substituted
N,N'-diaryl-o-phenylenediamine compounds or c) one or more hindered
phenol compounds; or a combination of both b) and c). Catalytic
antioxidants are more fully described in U.S. Pat. No. 8,048,833,
herein incorporated by reference in its entirety.
[0121] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.10 is H, alkyl, aryl or R.sup.11S(O)xR.sup.12 where R.sup.11
is an alkylene, alkenylene, or aralkylene group, R.sup.12 is a
higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is
0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to about
20 carbon atoms, and preferably contains from about 6 to 12 carbon
atoms. The aliphatic group is a saturated aliphatic group.
Preferably, both R.sup.8 and R.sup.9 are aromatic or substituted
aromatic groups, and the aromatic group may be a fused ring
aromatic group such as naphthyl. Aromatic groups R.sup.8 and
R.sup.9 may be joined together with other groups such as S.
[0122] Typical aromatic amines antioxidants have alkyl substituent
groups of at least about 6 carbon atoms. Examples of aliphatic
groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally,
the aliphatic groups will not contain more than about 14 carbon
atoms. The general types of amine antioxidants useful in the
present compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines.
Mixtures of two or more aromatic amines are also useful. Polymeric
amine antioxidants can also be used. Particular examples of
aromatic amine antioxidants useful in the present disclosure
include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0123] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0124] Preferred antioxidants include hindered phenols, arylamines.
These antioxidants may be used individually by type or in
combination with one another. Such additives may be used in an
amount of about 0.01 to 5 weight percent, preferably about 0.01 to
1.5 weight percent, more preferably zero to less than 1.5 weight
percent, more preferably zero to less than 1 weight percent.
[0125] Dispersants
[0126] During engine operation, oil-insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposition on metal surfaces. Dispersants
used in the formulation of the lubricant may be ashless or
ash-forming in nature. Preferably, the dispersant is ashless. So
called ashless dispersants are organic materials that form
substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents
discussed above form ash upon combustion.
[0127] Suitable dispersants typically contain a polar group
attached to a relatively high molecular weight hydrocarbon chain.
The polar group typically contains at least one element of
nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain
50 to 400 carbon atoms.
[0128] A particularly useful class of dispersants are the
(poly)alkenylsuccinic derivatives, typically produced by the
reaction of a long chain hydrocarbyl substituted succinic compound,
usually a hydrocarbyl substituted succinic anhydride, with a
polyhydroxy or polyamino compound. The long chain hydrocarbyl group
constituting the oleophilic portion of the molecule which confers
solubility in the oil, is normally a polyisobutylene group. Many
examples of this type of dispersant are well known commercially and
in the literature. Exemplary U.S. patents describing such
dispersants are U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666;
3,316,177; 3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904;
3,632,511; 3,787,374 and 4,234,435. Other types of dispersant are
described in U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025;
3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574;
3,725,277; 3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250;
3,519,565; 3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A
further description of dispersants may be found, for example, in
European Patent Application.
[0129] Hydrocarbyl-substituted succinic acid and
hydrocarbyl-substituted succinic anhydride derivatives are useful
dispersants. In particular, succinimide, succinate esters, or
succinate ester amides prepared by the reaction of a
hydrocarbon-substituted succinic acid compound preferably having at
least 50 carbon atoms in the hydrocarbon substituent, with at least
one equivalent of an alkylene amine are particularly useful.
[0130] Succinimides are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and amines. Molar
ratios can vary depending on the polyamine. For example, the molar
ratio of hydrocarbyl substituted succinic anhydride to TEPA can
vary from about 1:1 to about 5:1. Representative examples are shown
in U.S. Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746;
3,322,670; and 3,652,616, 3,948,800; and Canada Patent No.
1,094,044.
[0131] Succinate esters are formed by the condensation reaction
between hydrocarbyl substituted succinic anhydrides and alcohols or
polyols. Molar ratios can vary depending on the alcohol or polyol
used. For example, the condensation product of a hydrocarbyl
substituted succinic anhydride and pentaerythritol is a useful
dispersant.
[0132] Succinate ester amides are formed by condensation reaction
between hydrocarbyl substituted succinic anhydrides and alkanol
amines. For example, suitable alkanol amines include ethoxylated
polyalkylpolyamines, propoxylated polyalkylpolyamines and
polyalkenylpolyamines such as polyethylene polyamines. One example
is propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305.
[0133] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range
between 800 and 2,500 or more. The above products can be
post-reacted with various reagents such as sulfur, oxygen,
formaldehyde, carboxylic acids such as oleic acid. The above
products can also be post reacted with boron compounds such as
boric acid, borate esters or highly borated dispersants, to form
borated dispersants generally having from about 0.1 to about 5
moles of boron per mole of dispersant reaction product.
[0134] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No.
4,767,551, which is incorporated herein by reference. Process aids
and catalysts, such as oleic acid and sulfonic acids, can also be
part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S.
Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953;
3,798,165; and 3,803,039.
[0135] Typical high molecular weight aliphatic acid modified
Mannich condensation products useful in this disclosure can be
prepared from high molecular weight alkyl-substituted
hydroxyaromatics or HNR.sub.2 group-containing reactants.
[0136] Hydrocarbyl substituted amine ashless dispersant additives
are well known to one skilled in the art; see, for example, U.S.
Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209,
and 5,084,197.
[0137] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
about 500 to about 5000, or from about 1000 to about 3000, or about
1000 to about 2000, or a mixture of such hydrocarbylene groups,
often with high terminal vinylic groups. Other preferred
dispersants include succinic acid-esters and amides,
alkylphenol-polyamine-coupled Mannich adducts, their capped
derivatives, and other related components.
[0138] Polymethacrylate or polyacrylate derivatives are another
class of dispersants. These dispersants are typically prepared by
reacting a nitrogen containing monomer and a methacrylic or acrylic
acid esters containing 5-25 carbon atoms in the ester group.
Representative examples are shown in U.S. Pat. Nos. 2,100,993, and
6,323,164. Polymethacrylate and polyacrylate dispersants are
normally used as multifunctional viscosity modifiers. The lower
molecular weight versions can be used as lubricant dispersants or
fuel detergents.
[0139] Illustrative preferred dispersants useful in this disclosure
include those derived from polyalkenyl-substituted mono- or
dicarboxylic acid, anhydride or ester, which dispersant has a
polyalkenyl moiety with a number average molecular weight of at
least 900 and from greater than 1.3 to 1.7, preferably from greater
than 1.3 to 1.6, most preferably from greater than 1.3 to 1.5,
functional groups (mono- or dicarboxylic acid producing moieties)
per polyalkenyl moiety (a medium functionality dispersant).
Functionality (F) can be determined according to the following
formula:
F=(SAP.times.M.sub.n)/((112,200.times.A.I.)-(SAP.times.98))
wherein SAP is the saponification number (i.e., the number of
milligrams of KOH consumed in the complete neutralization of the
acid groups in one gram of the succinic-containing reaction
product, as determined according to ASTM D94); M.sub.n is the
number average molecular weight of the starting olefin polymer; and
A.I. is the percent active ingredient of the succinic-containing
reaction product (the remainder being unreacted olefin polymer,
succinic anhydride and diluent).
[0140] The polyalkenyl moiety of the dispersant may have a number
average molecular weight of at least 900, suitably at least 1500,
preferably between 1800 and 3000, such as between 2000 and 2800,
more preferably from about 2100 to 2500, and most preferably from
about 2200 to about 2400. The molecular weight of a dispersant is
generally expressed in terms of the molecular weight of the
polyalkenyl moiety. This is because the precise molecular weight
range of the dispersant depends on numerous parameters including
the type of polymer used to derive the dispersant, the number of
functional groups, and the type of nucleophilic group employed.
[0141] Polymer molecular weight, specifically M.sub.n, can be
determined by various known techniques. One convenient method is
gel permeation chromatography (GPC), which additionally provides
molecular weight distribution information (see W. W. Yau, J. J.
Kirkland and D. D. Bly, "Modern Size Exclusion Liquid
Chromatography", John Wiley and Sons, New York, 1979). Another
useful method for determining molecular weight, particularly for
lower molecular weight polymers, is vapor pressure osmometry (e.g.,
ASTM D3592).
[0142] The polyalkenyl moiety in a dispersant preferably has a
narrow molecular weight distribution (MWD), also referred to as
polydispersity, as determined by the ratio of weight average
molecular weight (M.sub.w) to number average molecular weight
(M.sub.n). Polymers having a M.sub.w/M.sub.n of less than 2.2,
preferably less than 2.0, are most desirable. Suitable polymers
have a polydispersity of from about 1.5 to 2.1, preferably from
about 1.6 to about 1.8.
[0143] Suitable polyalkenes employed in the formation of the
dispersants include homopolymers, interpolymers or lower molecular
weight hydrocarbons. One family of such polymers comprise polymers
of ethylene and/or at least one C.sub.3 to C.sub.2 alpha-olefin
having the formula H.sub.2C.dbd.CHR.sup.1 wherein R.sup.1 is a
straight or branched chain alkyl radical comprising 1 to 26 carbon
atoms and wherein the polymer contains carbon-to-carbon
unsaturation, and a high degree of terminal ethenylidene
unsaturation. Preferably, such polymers comprise interpolymers of
ethylene and at least one alpha-olefin of the above formula,
wherein R.sup.1 is alkyl of from 1 to 18 carbon atoms, and more
preferably is alkyl of from 1 to 8 carbon atoms, and more
preferably still of from 1 to 2 carbon atoms.
[0144] Another useful class of polymers is polymers prepared by
cationic polymerization of monomers such as isobutene and styrene.
Common polymers from this class include polyisobutenes obtained by
polymerization of a C.sub.4 refinery stream having a butene content
of 35 to 75% by wt., and an isobutene content of 30 to 60% by wt. A
preferred source of monomer for making poly-n-butenes is petroleum
feed streams such as Raffinate II. These feed stocks are disclosed
in the art such as in U.S. Pat. No. 4,952,739. A preferred
embodiment utilizes polyisobutylene prepared from a pure
isobutylene stream or a Raffinate I stream to prepare reactive
isobutylene polymers with terminal vinylidene olefins.
Polyisobutene polymers that may be employed are generally based on
a polymer chain of from 1500 to 3000.
[0145] The dispersant(s) are preferably non-polymeric (e.g., mono-
or bis-succinimides). Such dispersants can be prepared by
conventional processes such as disclosed in U.S. Patent Application
Publication No. 2008/0020950, the disclosure of which is
incorporated herein by reference.
[0146] The dispersant(s) can be borated by conventional means, as
generally disclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and
5,430,105.
[0147] Such dispersants may be used in an amount of about 0.01 to
20 weight percent or 0.01 to 10 weight percent, preferably about
0.5 to 8 weight percent, or more preferably 0.5 to 4 weight
percent. Or such dispersants may be used in an amount of about 2 to
12 weight percent, preferably about 4 to 10 weight percent, or more
preferably 6 to 9 weight percent. On an active ingredient basis,
such additives may be used in an amount of about 0.06 to 14 weight
percent, preferably about 0.3 to 6 weight percent. The hydrocarbon
portion of the dispersant atoms can range from C.sub.60 to
C.sub.1000, or from C.sub.70 to C.sub.300, or from C.sub.70 to
C.sub.200. These dispersants may contain both neutral and basic
nitrogen, and mixtures of both. Dispersants can be end-capped by
borates and/or cyclic carbonates. Nitrogen content in the finished
oil can vary from about 200 ppm by weight to about 2000 ppm by
weight, preferably from about 200 ppm by weight to about 1200 ppm
by weight. Basic nitrogen can vary from about 100 ppm by weight to
about 1000 ppm by weight, preferably from about 100 ppm by weight
to about 600 ppm by weight.
[0148] Dispersants as described herein are beneficially useful with
the compositions of this disclosure and substitute for some or all
of the surfactants of this disclosure. Further, in one embodiment,
preparation of the compositions of this disclosure using one or
more dispersants is achieved by combining ingredients of this
disclosure, plus optional base stocks and lubricant additives, in a
mixture at a temperature above the melting point of such
ingredients, particularly that of the one or more M-carboxylates
(M=H, metal, two or more metals, mixtures thereof).
[0149] As used herein, the dispersant concentrations are given on
an "as delivered" basis. Typically, the active dispersant is
delivered with a process oil. The "as delivered" dispersant
typically contains from about 20 weight percent to about 80 weight
percent, or from about 40 weight percent to about 60 weight
percent, of active dispersant in the "as delivered" dispersant
product.
[0150] Detergents
[0151] Illustrative detergents useful in this disclosure include,
for example, alkali metal detergents, alkaline earth metal
detergents, or mixtures of one or more alkali metal detergents and
one or more alkaline earth metal detergents. A typical detergent is
an anionic material that contains a long chain hydrophobic portion
of the molecule and a smaller anionic or oleophobic hydrophilic
portion of the molecule. The anionic portion of the detergent is
typically derived from an organic acid such as a sulfur-containing
acid, carboxylic acid (e.g., salicylic acid), phosphorus-containing
acid, phenol, or mixtures thereof. The counterion is typically an
alkaline earth or alkali metal. The detergent can be overbased as
described herein.
[0152] The detergent is preferably a metal salt of an organic or
inorganic acid, a metal salt of a phenol, or mixtures thereof. The
metal is preferably selected from an alkali metal, an alkaline
earth metal, and mixtures thereof. The organic or inorganic acid is
selected from an aliphatic organic or inorganic acid, a
cycloaliphatic organic or inorganic acid, an aromatic organic or
inorganic acid, and mixtures thereof.
[0153] The metal is preferably selected from an alkali metal, an
alkaline earth metal, and mixtures thereof. More preferably, the
metal is selected from calcium (Ca), magnesium (Mg), and mixtures
thereof.
[0154] The organic acid or inorganic acid is preferably selected
from a sulfur-containing acid, a carboxylic acid, a
phosphorus-containing acid, and mixtures thereof.
[0155] Preferably, the metal salt of an organic or inorganic acid
or the metal salt of a phenol comprises calcium phenate, calcium
sulfonate, calcium salicylate, magnesium phenate, magnesium
sulfonate, magnesium salicylate, an overbased detergent, and
mixtures thereof.
[0156] Salts that contain a substantially stochiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) with an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly
overbased, or highly overbased. These detergents can be used in
mixtures of neutral, overbased, highly overbased calcium
salicylate, sulfonates, phenates and/or magnesium salicylate,
sulfonates, phenates. The TBN ranges can vary from low, medium to
high TBN products, including as low as 0 to as high as 600.
Preferably the TBN delivered by the detergent is between 1 and 20.
More preferably between 1 and 12. Mixtures of low, medium, high TBN
can be used, along with mixtures of calcium and magnesium metal
based detergents, and including sulfonates, phenates, salicylates,
and carboxylates. A detergent mixture with a metal ratio of 1, in
conjunction of a detergent with a metal ratio of 2, and as high as
a detergent with a metal ratio of 5, can be used. Borated
detergents can also be used.
[0157] Alkaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH).sub.2, BaO, Ba(OH).sub.2,
MgO, Mg(OH).sub.2, for example) with an alkyl phenol or sulfurized
alkylphenol. Useful alkyl groups include straight chain or branched
C.sub.1-C.sub.30 alkyl groups, preferably, C.sub.4-C.sub.20 or
mixtures thereof. Examples of suitable phenols include
isobutylphenol, 2-ethylhexylphenol, nonylphenol, dodecyl phenol,
and the like. It should be noted that starting alkylphenols may
contain more than one alkyl substituent that are each independently
straight chain or branched and can be used from 0.5 to 6 weight
percent. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These
methods include heating a mixture of alkylphenol and sulfurizing
agent (including elemental sulfur, sulfur halides such as sulfur
dichloride, and the like) and then reacting the sulfurized phenol
with an alkaline earth metal base.
[0158] In accordance with this disclosure, metal salts of
carboxylic acids are preferred detergents. These carboxylic acid
detergents may be prepared by reacting a basic metal compound with
at least one carboxylic acid and removing free water from the
reaction product. These compounds may be overbased to produce the
desired TBN level. Detergents made from salicylic acid are one
preferred class of detergents derived from carboxylic acids. Useful
salicylates include long chain alkyl salicylates. One useful family
of compositions is of the formula
##STR00001##
where R is an alkyl group having 1 to about 30 carbon atoms, n is
an integer from 1 to 4, and M is an alkaline earth metal. Preferred
R groups are alkyl chains of at least C.sub.11, preferably C.sub.13
or greater. R may be optionally substituted with substituents that
do not interfere with the detergent's function. M is preferably,
calcium, magnesium, barium, or mixtures thereof. More preferably, M
is calcium.
[0159] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The
metal salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0160] Alkaline earth metal phosphates are also used as detergents
and are known in the art.
[0161] Detergents may be simple detergents or what is known as
hybrid or complex detergents. The latter detergents can provide the
properties of two detergents without the need to blend separate
materials. See U.S. Pat. No. 6,034,039.
[0162] Preferred detergents include calcium sulfonates, magnesium
sulfonates, calcium salicylates, magnesium salicylates, calcium
phenates, magnesium phenates, and other related components
(including borated detergents), and mixtures thereof. Preferred
mixtures of detergents include magnesium sulfonate and calcium
salicylate, magnesium sulfonate and calcium sulfonate, magnesium
sulfonate and calcium phenate, calcium phenate and calcium
salicylate, calcium phenate and calcium sulfonate, calcium phenate
and magnesium salicylate, calcium phenate and magnesium phenate.
Overbased detergents are also preferred.
[0163] The detergent concentration in the lubricant compositions of
this disclosure can range from about 0.5 to about 6.0 weight
percent, preferably about 0.6 to 5.0 weight percent, and more
preferably from about 0.8 weight percent to about 4.0 weight
percent, based on the total weight of the lubricant
composition.
[0164] As used herein, the detergent concentrations are given on an
"as delivered" basis. Typically, the active detergent is delivered
with a process oil. The "as delivered" detergent typically contains
from about 20 weight percent to about 100 weight percent, or from
about 40 weight percent to about 60 weight percent, of active
detergent in the "as delivered" detergent product.
[0165] Viscosity Modifiers
[0166] Viscosity modifiers (also known as viscosity index improvers
(VI improvers), and viscosity improvers) can be included in the
lubricant compositions of this disclosure.
[0167] Viscosity modifiers provide lubricants with high and low
temperature operability. These additives impart shear stability at
elevated temperatures and acceptable viscosity at low
temperatures.
[0168] Suitable viscosity modifiers include high molecular weight
hydrocarbons, polyesters and viscosity modifier dispersants that
function as both a viscosity modifier and a dispersant. Typical
molecular weights of these polymers are between about 10,000 to
1,500,000, more typically about 20,000 to 1,200,000, and even more
typically between about 50,000 and 1,000,000.
[0169] Examples of suitable viscosity modifiers are linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes. Polyisobutylene is a commonly used
viscosity modifier. Another suitable viscosity modifier is
polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity modifiers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, and polyacrylates (copolymers
of various chain length acrylates, for example). Specific examples
include styrene-isoprene or styrene-butadiene based polymers of
50,000 to 200,000 molecular weight.
[0170] Olefin copolymers are commercially available from Chevron
Oronite Company LLC under the trade designation "PARATONE.RTM."
(such as "PARATONE.RTM. 8921" and "PARATONE.RTM. 8941"); from Afton
Chemical Corporation under the trade designation "HiTEC.RTM." (such
as "HiTEC.RTM. 5850B"; and from The Lubrizol Corporation under the
trade designation "Lubrizol.RTM. 7067C". Hydrogenated polyisoprene
star polymers are commercially available from Infineum
International Limited, e.g., under the trade designation "SV200"
and "SV600". Hydrogenated diene-styrene block copolymers are
commercially available from Infineum International Limited, e.g.,
under the trade designation "SV 50".
[0171] The polymethacrylate or polyacrylate polymers can be linear
polymers which are available from Evnoik Industries under the trade
designation "Viscoplex.RTM." (e.g., Viscoplex 6-954) or star
polymers which are available from Lubrizol Corporation under the
trade designation Asteric.TM. (e.g., Lubrizol 87708 and Lubrizol
87725).
[0172] Illustrative vinyl aromatic-containing polymers useful in
this disclosure may be derived predominantly from vinyl aromatic
hydrocarbon monomer. Illustrative vinyl aromatic-containing
copolymers useful in this disclosure may be represented by the
following general formula:
A-B
wherein A is a polymeric block derived predominantly from vinyl
aromatic hydrocarbon monomer, and B is a polymeric block derived
predominantly from conjugated diene monomer.
[0173] In an embodiment of this disclosure, the viscosity modifiers
may be used in an amount of less than about 10 weight percent,
preferably less than about 7 weight percent, more preferably less
than about 4 weight percent, and in certain instances, may be used
at less than 2 weight percent, preferably less than about 1 weight
percent, and more preferably less than about 0.5 weight percent,
based on the total weight of the lubricant composition. Viscosity
modifiers are typically added as concentrates, in large amounts of
diluent oil.
[0174] As used herein, the viscosity modifier concentrations are
given on an "as delivered" basis. Typically, the active polymer is
delivered with a diluent oil. The "as delivered" viscosity modifier
typically contains from 20 weight percent to 75 weight percent of
an active polymer for polymethacrylate or polyacrylate polymers, or
from 8 weight percent to 20 weight percent of an active polymer for
olefin copolymers, hydrogenated polyisoprene star polymers, or
hydrogenated diene-styrene block copolymers, in the "as delivered"
polymer concentrate.
[0175] Pour Point Depressants (PPDs)
[0176] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
disclosure if desired. These pour point depressant may be added to
lubricant compositions of the present disclosure to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
polymethacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655, 479; 2,666,746;
2,721,877; 2,721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Such additives may be
used in an amount of about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent.
[0177] Seal Compatibility Agents
[0178] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricants
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Such additives may be used in an amount of
about 0.01 to 3 weight percent, preferably about 0.01 to 2 weight
percent.
[0179] Antifoam Agents
[0180] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Anti-foam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 weight
percent and often less than 0.1 weight percent.
[0181] Inhibitors and Antirust Additives
[0182] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available.
[0183] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent.
[0184] Friction Modifiers
[0185] A friction modifier is any material or materials that can
alter the coefficient of friction of a surface lubricated by any
lubricant or fluid containing such material(s). Friction modifiers,
also known as friction reducers, or lubricity agents or oiliness
agents, and other such agents that change the ability of base oils,
formulated lubricant compositions, or functional fluids, to modify
the coefficient of friction of a lubricated surface may be
effectively used in combination with the base oils or lubricant
compositions of the present disclosure if desired. Friction
modifiers that lower the coefficient of friction are particularly
advantageous in combination with the base oils and lube
compositions of this disclosure.
[0186] Illustrative friction modifiers may include, for example,
organometallic compounds or materials, or mixtures thereof.
Illustrative organometallic friction modifiers useful in the
lubricant compositions of this disclosure include, for example,
molybdenum amine, molybdenum diamine, an organotungstenate, a
molybdenum dithiocarbamate, molybdenum dithiophosphates, molybdenum
amine complexes, molybdenum carboxylates, and the like, and
mixtures thereof. Similar tungsten based compounds may be
preferable.
[0187] Other illustrative friction modifiers useful in the
lubricant compositions of this disclosure include, for example,
alkoxylated fatty acid esters, alkanolamides, polyol fatty acid
esters, borated glycerol fatty acid esters, fatty alcohol ethers,
and mixtures thereof.
[0188] Illustrative alkoxylated fatty acid esters include, for
example, polyoxyethylene stearate, fatty acid polyglycol ester, and
the like. These can include polyoxypropylene stearate,
polyoxybutylene stearate, polyoxyethylene isosterate,
polyoxypropylene isostearate, polyoxyethylene palmitate, and the
like.
[0189] Illustrative alkanolamides include, for example, lauric acid
diethylalkanolamide, palmic acid diethylalkanolamide, and the like.
These can include oleic acid diethyalkanolamide, stearic acid
diethylalkanolamide, oleic acid diethylalkanolamide,
polyethoxylated hydrocarbylamides, polypropoxylated
hydrocarbylamides, and the like.
[0190] Illustrative polyol fatty acid esters include, for example,
glycerol mono-oleate, saturated mono-, di-, and tri-glyceride
esters, glycerol mono-stearate, and the like. These can include
polyol esters, hydroxyl-containing polyol esters, and the like.
[0191] Illustrative borated glycerol fatty acid esters include, for
example, borated glycerol mono-oleate, borated saturated mono-,
di-, and tri-glyceride esters, borated glycerol mono-sterate, and
the like. In addition to glycerol polyols, these can include
trimethylolpropane, pentaerythritol, sorbitan, and the like. These
esters can be polyol monocarboxylate esters, polyol dicarboxylate
esters, and on occasion polyoltricarboxylate esters. Preferred can
be the glycerol mono-oleates, glycerol dioleates, glycerol
trioleates, glycerol monostearates, glycerol distearates, and
glycerol tristearates and the corresponding glycerol
monopalmitates, glycerol dipalmitates, and glycerol tripalmitates,
and the respective isostearates, linoleates, and the like. On
occasion the glycerol esters can be preferred as well as mixtures
containing any of these. Ethoxylated, propoxylated, butoxylated
fatty acid esters of polyols, especially using glycerol as
underlying polyol can be preferred.
[0192] Illustrative fatty alcohol ethers include, for example,
stearyl ether, myristyl ether, and the like. Alcohols, including
those that have carbon numbers from C.sub.3 to C.sub.50, can be
ethoxylated, propoxylated, or butoxylated to form the corresponding
fatty alkyl ethers. The underlying alcohol portion can preferably
be stearyl, myristyl, C.sub.11-C.sub.13 hydrocarbon, oleyl,
isosteryl, and the like.
[0193] The lubricant compositions of this disclosure exhibit
desired properties, e.g., wear control, in the presence or absence
of a friction modifier.
[0194] Useful concentrations of friction modifiers may range from
0.01 weight percent to 5 weight percent, or about 0.1 weight
percent to about 2.5 weight percent, or about 0.1 weight percent to
about 1.5 weight percent, or about 0.1 weight percent to about 1
weight percent. Concentrations of molybdenum-containing materials
are often described in terms of Mo metal concentration.
Advantageous concentrations of Mo may range from 25 ppm to 700 ppm
or more, and often with a preferred range of 50-200 ppm. Friction
modifiers of all types may be used alone or in mixtures with the
materials of this disclosure. Often mixtures of two or more
friction modifiers, or mixtures of friction modifier(s) with
alternate surface active material(s), are also desirable.
[0195] Antiwear Additives
[0196] A metal alkylthiophosphate and more particularly a metal
dialkyl dithio phosphate in which the metal constituent is zinc, or
zinc dialkyl dithio phosphate (ZDDP) can be a useful component of
the lubricant compositions of this disclosure. ZDDP can be derived
from primary alcohols, secondary alcohols or mixtures thereof. ZDDP
compounds generally are of the formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2
where R.sup.1 and R.sup.2 are C.sub.1-C.sub.18 alkyl groups,
preferably C.sub.2-C.sub.12 alkyl groups. These alkyl groups may be
straight chain or branched. Alcohols used in the ZDDP can be
propanol, 2-propanol, butanol, secondary butanol, pentanols,
hexanols such as 4-methyl-2-pentanol, n-hexanol, n-octanol, 2-ethyl
hexanol, alkylated phenols, and the like. Mixtures of secondary
alcohols or of primary and secondary alcohol can be preferred.
Alkyl aryl groups may also be used.
[0197] Preferable zinc dithiophosphates which are commercially
available include secondary zinc dithiophosphates such as those
available from for example, The Lubrizol Corporation under the
trade designations "LZ 677A", "LZ 1095" and "LZ 1371", from for
example Chevron Oronite under the trade designation "OLOA 262" and
from for example Afton Chemical under the trade designation "HITEC
7169".
[0198] The ZDDP is typically used in amounts of from about 0.3
weight percent to about 1.5 weight percent, preferably from about
0.4 weight percent to about 1.2 weight percent, more preferably
from about 0.5 weight percent to about 1.0 weight percent, and even
more preferably from about 0.6 weight percent to about 0.8 weight
percent, based on the total weight of the lubricant, although more
or less can often be used advantageously. Preferably, the ZDDP is a
secondary ZDDP and present in an amount of from about 0.6 to 1.0
weight percent of the total weight of the lubricant
composition.
[0199] The types and quantities of performance additives used in
combination with the instant disclosure in lubricant compositions
are not limited by the examples shown herein as illustrations.
[0200] When lubricant compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
disclosure are shown in Table 1 below.
[0201] It is noted that many of the additives are shipped from the
additive manufacturer as a concentrate, containing one or more
additives together, with a certain amount of base oil diluents.
Accordingly, the weight amounts in the table below, as well as
other amounts mentioned herein, are directed to the amount of
active ingredient (that is the non-diluent portion of the
ingredient). The weight percent (wt %) indicated below is based on
the total weight of the lubricant composition.
TABLE-US-00002 TABLE 1 Typical Amounts of Other Lubricant
Components Approximate Approximate Compound wt % (Useful) wt %
(Preferred) Antiwear 0.1-2 0.5-1 Dispersant 0.1-20 0.1-8 Detergent
0.1-20 0.1-8 Antioxidant 0.1-10 0.1-5 Friction Modifier 0.01-5
0.01-1.5 Pour Point Depressant 0.0-5 0.01-1.5 (PPD) Anti-foam Agent
0.001-3 0.001-0.15 Viscosity Index Improver 0.0-8 0.1-6 (pure
polymer basis) Inhibitor and Antirust 0.01-5 0.01-1.5
[0202] The foregoing additives are all commercially available
materials. These additives may be added independently but are
usually precombined in packages which can be obtained from
suppliers of lubricant oil additives. Additive packages with a
variety of ingredients, proportions and characteristics are
available and selection of the appropriate package will take the
requisite use of the ultimate composition into account.
[0203] The concentrations of the low and high viscosity base stock
blends described herein have the ability to control traction
coefficient and film thickness in the lubricant compositions
incorporating the blends. The use of these fluid blends is
desirable in lubricant compositions in the presence of salicylate,
sulfonate and phenate detergents, along with antioxidants and
ashless antioxidants, along with succinimide based dispersants,
along with zinc dialkyldithiophosphates, along with organic and
metallic friction modifiers, along with corrosion inhibitors, and
along with defoamants. The low and high viscosity base stock blends
are useful in all lubricant applications.
[0204] The disclosure is directed to base stock blends useful in
the preparation of finished gear, transmission, engine, and
industrial lubricants, and in a preferred embodiment are used as
lubricants for non-conforming concentrated contacts with high
sliding such as spur gears, helical gears, hypoid gears, bevel
gears, worm gears and the like.
[0205] Lubricant compositions according to the present disclosure
are particularly useful in applications wherein there are EHL
contacts that have a component of sliding. Examples include
spherical roller bearings, deep groove ball bearings, angular
contact bearings among others. Additionally, most gear systems
contain multiple sliding EHL contacts between meshing gear teeth.
Examples include spur gears, helical gears, hypoid gears, bevel
bears, worm gears, and the like.
[0206] For industrial gears, one common type of gearing is worm
gears. Worm gears form an extended elliptical contact against the
wheel and operate under high sliding EHL conditions. Therefore,
there is a significant benefit to the lubricant compositions of
this disclosure in terms of energy savings.
[0207] Quantifying the amount of efficiency that can be expected is
difficult because it is dependent on many factors, in worm gears
for example, the amount of efficiency seen will depend on many
factors including the shaft bearings, seals, churning losses, gear
meshing, gear reduction ratios, etc. However, it is estimated that
the gains may be substantial due to the high sliding and generally
high energy losses. Steel gears are generally more efficient than
bronze worm gears, and therefore, the absolute efficiency gains
will be lessened.
[0208] Nevertheless, one of ordinary skill in the art can quantify
fuel efficiency of a gear system by numerous methods and more
particularly can determine an improvement in such system for
embodiments of compositions according to the present disclosure
compared with lubricant composition that do not show an
improvement. Likewise, the energy efficiency of a machine operating
the gear system can be readily determined and comparisons made.
[0209] Rolling element bearings have many configurations and
depending on the type of configuration, there may or may not be a
benefit to having a lubricant composition of this disclosure. This
may also be determined by one of ordinary skill in the art in
possession of the present disclosure. Where there is sliding
between the ball and the raceway, the oil is being sheared such
that the lubricants described in this disclosure will reduce the
energy losses.
[0210] The present disclosure is particularly beneficial in any
system that includes machine elements that contain gears of any
kind and rolling element bearings. Examples of such systems include
electricity generating systems, industrial manufacturing equipment
such as paper, steel and cement mills, hydraulic systems,
automotive drive trains, aircraft propulsion systems, etc. It will
be recognized by one of ordinary skill in the art in possession of
the present disclosure that the various embodiments set forth
herein, including preferred and more preferred embodiments, may be
combined in a manner consistent with achieving desired lubricant
properties.
[0211] The following non-limiting examples are provided to
illustrate the disclosure.
EXAMPLES
[0212] The Examples focus are directed to traction and pressure
viscosity coefficient behaviors of PAO lubricant base fluids and
their blends. The Examples are separated into two parts, selected
single-component lubricant base stocks and selected two-component
binary blends of these same lubricants. The lubricants were tested
in a Mini-Traction Machine (MTM).
[0213] As used herein, traction coefficient was determined by a PCS
Instruments MTM using standard steel specimens, a lubricant
temperature of 100.degree. C., a 1.0 GPa peak contact pressure, a
lubricant entraining velocity of 2 ms, and a 25% slide-to-roll
ratio (hereinafter "MTM TC Method"). Suitable MTM testing
properties include, for example, 0.1 to 3.5 GPa, peak contact
pressure, -40.degree. C. to 200.degree. C. lubricant temperature,
and a lubricant entraining velocity of from 0.25 to 10.0 m/s. Other
methods can be used to determine traction coefficient provided the
measurements are consistent with a given method in making any
comparisons. As used herein, viscosity was determined by ASTM
D-445.
[0214] A listing of base oils used in the Examples is set forth in
Table 2 below. As used herein and FIGS. 1-8, mPAO 150 is SpectraSyn
Elite.RTM. 150, mPAO 300 is SpectraSyn Elite.RTM. 300, mPAO 600 is
600 cSt Alpha Olefin, and mPAO 1000 is 1000 cSt Alpha Olefin.
TABLE-US-00003 TABLE 2 Low molecular base oils High molecular base
oil PAO 2 PAO 100 PAO 4 mPAO 150 PAO 6 mPAO 300 PAO 8 mPAO 600 mPAO
1000
[0215] A further listing of base oils used in the Examples is set
forth in Table 3 below. Bimodal blends were done in two ways as
shown in Table 3. First, a series of low viscosity base oil (i.e.,
PAO 2, PAO 4, PAO 6 or PAO 8) were blended with the high viscosity
base oil mPAO150. Second, a series of high viscosity base oil
(i.e., PAO 100, mPAO 150, mPAO 300, mPAO 600 or mPAO 1000) were
blended with a low viscosity base oil PAO 4. Table 4 shows bimodal
blend results for kinematic viscosity determined by ASTM D-445, and
traction coefficient determined by MTM TC Method.
TABLE-US-00004 TABLE 3 Low molecular base Low molecular base oils
High molecular base oil oil Concentration % PAO 2 mPAO 150 10, 25,
50, 75, 90 PAO 4 mPAO 150 25, 50, 65, 75 PAO 6 mPAO 150 10, 25, 50,
75, 90 PAO 8 mPAO 150 30, 50, 75, 90 PAO 4 PAO 100 25, 50, 75, 90
PAO 4 mPAO 150 25, 50, 75 PAO 4 mPAO 300 25, 50, 75 PAO 4 mPAO 600
25, 50, 75 PAO 4 mPAO 1000 25, 50, 75, 90
TABLE-US-00005 TABLE 4 KV @100 C. Traction KV @100 C. Traction
mPAO150/PAO2 blends PAO100 blends 7171/90% PAO2 2.366 0.0097
PAO100/PAO4.25% 46. 0.0171 7171/75% PAO2 4.431 0. .sup.
PAO100/PAO4.50% 20. 0.014 7171/50% PAO2 22.55 0.01 PAO100/PAO4.75%
5.31 0.0114 7171/25% PAO2 40.28 0.015 7171/10% PAO2 9.46 0.0181
mPAO 300 blends PAO300/75% PAO4 11.86 0.0114 PAO300/50% PAO4 33.6
0.0138 PAO300/25% PAO4 93. 3 0.0164 mPAO150/PAO6 blends 7171/25%
PAO6 61.72 0.018 7171/50% PAO6 26.73 0.0157 mPAO 600 blends
7171/75% PAO6 22.51 0.0148 PAO600/50% PAO4 7.363 0.0 209 7171/10%
PAO6 110.9 0.0196 PAO600/75% PAO4 16.18 0.0 3 7171/90% PAO6 7.889
0.013 PAO600/90% PAO4 7.402 0.0 3 PAO600/25% PAO4 167.4 0.0 76
PAO600/30% PAO4 3.18 0.0 39 PAO600/10% PAO4 3 .1 0.0 6 mPAO150/PAO6
blends 7171/90% PAO8 10.56 0.0152 7171/50% PAO8 32.23 0.018
7171/25% PAO8 58.55 0.0138 mPAO 1000 blends 7171/75% PAO8 15.05
0.0137 mPAO1000/25% PAO4 256.4 0.016 mPAO1000/50% PAO4 74.63 0.0131
mPAO1000/75% PAO4 .71 0.0117 mPAO1000/90% PAO4 2.482 0.0103
mPAO150/PAO4 Blends 7171/75% PAO2 9.3 0.0119 7171/6 % PA4 13 0.0124
7171/ 0% PAO4 21.89 0.0134 7171/25% PAO4 54.89 0.0157 indicates
data missing or illegible when filed
[0216] A summary of the traction responses for the base oils is
shown in FIG. 1. Reproducibility errors have been calculated for
some of the base oils, and they are represented by arrow lines in
FIG. 1. In particular, FIG. 1 graphically shows traction
performance for neat base oils, PAO 4, PAO 8, PAO 40, PAO 100, mPAO
150, mPAO 300, and mPAO 600.
[0217] FIG. 1 shows the following: tractions increase as the
viscosity of the base oils increase up to a KV 40; neat oil
traction responses reach a plateau around PAO40 or before;
variability of the test increases as traction increases (arrow
lines); and after viscosity surpasses mPAO 150, shear heating
effects contribution (shear heating) has a substantial effect on
traction performance.
[0218] The base oil mPAO 150 was mixed with a variety of low
viscosity (LV) base oils (i.e., PAO 2, PAO 4, PAO 6 or PAO 8) to
make the fluids in Table 3. The results have showed that when high
concentration of the LV molecules is used, meaning final blends
have lower viscosity; the traction decreases. An important
observation is as the molecular weight of the LV component used to
make the blends (lower viscosity fluids--PAO
8>PAO6>PAO4>PAO 2) is decreased, the traction of the final
blend decreases as well. This is conventional behavior. The
conventional wisdom is that traction is completely dependent on
lubricant viscosity (see FIG. 2). This behavior has been well
explored and observed with other LV base oils and it is attributed
to a lower pressure viscosity coefficient meaning lower viscosity
at pressure in the EHL contact zone.
[0219] FIG. 2 graphically shows traction performance for blends
made with constant high viscosity base oil (mPAO 150) and varied
low viscosity base oil (i.e., PAO 2, PAO 4, PAO 6 or PAO 8) under
conditions 1 GPa, 25% SRR at 100.degree. C. Traction coefficient
shows a clear dependency on oil viscosity and type of low viscosity
component.
[0220] In particular, FIG. 2 shows the following: as the
concentration of the low viscosity component is increased, the
viscosity of the fluid decreases and traction also decreases; a
significant decrease in traction also observed when the LV fluid
was replaced with a lower molecular weight fluid; at the same
concentration of LV component, traction trend behave as follows:
PAO 8>PAO6>PAO4>PAO 2; and in the case of PAO 2 and PAO 8,
minimum traction points were observed lower than the neat LV
component. The PAO 2 mixtures and PAO 2 neat are situated outside
of the EHL region (mix boundary region), hence having higher
traction due to metal-metal contact.
[0221] The base oil PAO 4 was blended with a variety of high
viscosity (HV) base oils at different ratios (i.e., PAO 100, mPAO
150, mPAO 300, mPAO 600 or mPAO 1000) with the traction
subsequently measured. The data is summarized in FIG. 3.
[0222] FIG. 3 graphically shows traction performance for blends of
multiple high molecular weight PAO polymers (PAO 100, mPAO 150,
mPAO 300, mPAO 600, mPAO 1000) with PAO 4. FIG. 3 shows traction
increase as viscosity of the bimodal blends increase.
[0223] In particular, FIG. 3 shows the following: the expected
behavior of traction being controlled by viscosity; and extreme
bimodal behavior confirmed, meaning the more separation of the
viscosities of the components used to make the final fluids, the
lower the traction at the same viscosity.
[0224] The same data in FIG. 3 was plotted against the
concentration of the LV component in the fluid, in this case PAO 4
(see FIG. 4). The expected behavior was to observe something
similar to FIG. 2, where the viscosity of the fluids control the
traction performance of the fluids, however in these experiments a
different response was observed. Unresponsiveness was observed to
changes in traction as the viscosities of the fluids was
significantly increased for all fluids with similar PAO 4
compositions (compare FIGS. 2 and 4). These means that at a given
PAO 4 concentration, these blends showed equivalent traction
performance despite the lubricant viscosity being varied and high
viscosity fluids used. For example, similar traction performance
was observed at 25% PAO 4 independently of the use of HV materials,
e.g., PAO 100, mPAO 150, 300, 600 or 1000. This performance is
totally contradicted to the conventional knowledge of bimodal
blends. In addition, initial data confirmed a similar phenomena if
PAO 4 is replaced with PAO 6.
[0225] While not wishing to be bound by any particular theory,
potential explanations for this performance include the following:
shear thinning; inlet size separation; induced phase transition;
and induced phase separation.
[0226] FIG. 4 graphically shows traction performance for PAO
bimodal blends made by mixing high viscosity base oil (i.e., PAO
40, PAO 100, mPAO 150, mPAO 300, mPAO 600 or mPAO 1000) with a low
viscosity base oil PAO 4 under conditions 1 GPa, 25% SRR at
100.degree. C. FIG. 4 shows that traction coefficients are
predominantly controlled by PAO4 concentration, and are independent
of the high viscosity component and finished oil KV.
[0227] FIG. 5 graphically shows that traction coefficient is
controlled by the low viscosity component of bimodal blends and is
independent of finish oil viscosity.
[0228] FIG. 6 graphically shows that traction coefficient is
controlled by high viscosity base oil (i.e., Lucant base oil) at
concentration higher than 15 percent by weight. At a low
concentration of high viscosity base oils, the traction increased
unexpectedly as the concentration of PAO 4 increased (viscosity
decreasing).
[0229] The Examples show that the bimodal blend traction
coefficient is independent of lubricant viscosity and is instead
dependent upon the low viscosity (LV) fluid concentration.
Further Embodiments
Embodiment 1
[0230] A lubricant composition comprising a base stock blend as a
major component, and at least one lubricant additive, as a minor
component; wherein the base stock blend comprises at least one
first base stock having a viscosity from 1 cSt to 50 cSt at
40.degree. C. as determined by ASTM D-445, and at least one second
base stock having viscosity from 100 cSt to 2000 cSt at 40.degree.
C. as determined by ASTM D-445; wherein the first base stock is
present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend; and
wherein the second base stock is miscible with the first base
stock.
Embodiment 2
[0231] The lubricant composition of embodiment 1 wherein, in a
mechanical component having sliding or rolling between contacting
surfaces lubricated with the lubricant composition, traction
coefficient (Tc) is controlled by concentration of the first base
stock, and film thickness is controlled by the concentration of the
second base stock.
Embodiment 3
[0232] The lubricant composition of embodiment 1 wherein the first
base stock is present in an amount from 60 to 95 weight percent of
the base stock blend, and the second base stock is present in an
amount from 5 to 40 weight percent of the base stock blend.
Embodiment 4
[0233] The lubricant composition of embodiment 1 wherein the first
base stock comprises a Group I, Group II, Group III, Group IV or
Group V base oil, and the second base stock comprises a Group I,
Group II, Group III, Group IV or Group V base oil.
Embodiment 5
[0234] The lubricant composition of embodiment 1 wherein the first
base stock comprises a polyalphaolefin (PAO) base oil, and the
second base stock comprises a polyalphaolefin (PAO) base oil or a
metallocene catalyzed polyalphaolefin (PAO) base oil.
Embodiment 6
[0235] The lubricant composition of embodiment 1 wherein the base
stock blend is present in an amount from 70 to 95 weight percent of
the lubricant composition.
Embodiment 7
[0236] The lubricant composition of embodiment 1 wherein the first
base stock has a traction coefficient (Tc) of from 0.008 to 0.015
as determined by MTM TC Method, the second base stock has a
traction coefficient (Tc) of from 0.008 to 0.025 as determined by
MTM TC Method, and the lubricant composition has a traction
coefficient (Tc) of less than 0.15 as determined by MTM TC
Method.
Embodiment 8
[0237] The lubricant composition of embodiment 1 further comprising
one or more of a viscosity modifier, dispersant, detergent,
antioxidant, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, and anti-rust additive.
Embodiment 9
[0238] The lubricant composition of embodiment 1 wherein traction
coefficient (Tc) is independent of viscosity of the lubricant
composition.
Embodiment 10
[0239] The lubricant composition of embodiment 1 wherein the base
stock blend is a bimodal blend.
Embodiment 11
[0240] The lubricant composition of embodiment 1 wherein, in a
mechanical component having sliding or rolling between contacting
surfaces lubricated with the lubricant composition, a phase
separation or transition is induced in a mechanical contact
zone.
Embodiment 12
[0241] The lubricant composition of embodiment 1 which is a
finished gear, transmission, engine or industrial lubricant.
Embodiment 13
[0242] A method for controlling traction coefficient (Tc) of a
lubricant composition, said method comprising blending at least one
first base stock with at least one second base stock to give a base
stock blend; wherein the first base stock has a viscosity from 1
cSt to 50 cSt at 40.degree. C. as determined by ASTM D-445, and the
second base stock has a viscosity from 100 cSt to 2000 cSt at
40.degree. C. as determined by ASTM D-445; wherein the first base
stock is miscible with the second base stock; and wherein the first
base stock is present in the base stock blend in an amount
sufficient to control traction coefficient (Tc) of the lubricant
composition.
Embodiment 14
[0243] The method of embodiment 13 wherein, in a mechanical
component having sliding or rolling between contacting surfaces
lubricated with the lubricant composition, traction coefficient
(Tc) is controlled by concentration of the first base stock, and
film thickness is controlled by the concentration of the second
base stock.
Embodiment 15
[0244] The method of embodiment 13 wherein the first base stock is
present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend.
Embodiment 16
[0245] The method of embodiment 13 wherein the first base stock is
present in an amount from 60 to 95 weight percent of the base stock
blend, and the second base stock is present in an amount from 5 to
40 weight percent of the base stock blend.
Embodiment 17
[0246] The method of embodiment 13 wherein the first base stock
comprises a Group I, Group II, Group III, Group IV or Group V base
oil, and the second base stock comprises a Group I, Group II, Group
III, Group IV or Group V base oil.
Embodiment 18
[0247] The method of embodiment 13 wherein the first base stock
comprises a polyalphaolefin (PAO) base oil, and the second base
stock comprises a polyalphaolefin (PAO) base oil or a metallocene
catalyzed polyalphaolefin (PAO) base oil.
Embodiment 19
[0248] The method of embodiment 13 wherein the base stock blend is
present in an amount from 70 to 95 weight percent of the lubricant
composition.
Embodiment 20
[0249] The method of embodiment 13 wherein the first base stock has
a traction coefficient (Tc) of from 0.008 to 0.015 as determined by
MTM TC Method, the second base stock has a traction coefficient
(Tc) of from 0.008 to 0.025 as determined by MTM TC Method, and the
lubricant composition has a traction coefficient (Tc) of less than
0.15 as determined by MTM TC Method.
Embodiment 20
[0250] The method of embodiment 13 wherein the lubricant
composition further comprises one or more of a viscosity modifier,
dispersant, detergent, antioxidant, pour point depressant,
corrosion inhibitor, metal deactivator, seal compatibility
additive, anti-foam agent, inhibitor, and anti-rust additive.
Embodiment 21
[0251] The method of embodiment 13 wherein traction coefficient
(Tc) is independent of viscosity of the lubricant composition.
Embodiment 22
[0252] The method of embodiment 13 wherein the base stock blend is
a bimodal blend.
Embodiment 23
[0253] The method of embodiment 13 wherein, in the mechanical
component having sliding or rolling between contacting surfaces
lubricated with the lubricant composition, a phase separation or
transition is induced in a mechanical contact zone.
Embodiment 24
[0254] The method of embodiment 13 wherein the lubricant
composition is a finished gear, transmission, engine or industrial
lubricant.
Embodiment 25
[0255] A method for controlling film thickness of a lubricant
composition, said method comprising blending at least one first
base stock with at least one second base stock to give a base stock
blend; wherein the first base stock has a viscosity from 1 cSt to
50 cSt at 40.degree. C. as determined by ASTM D-445, and the second
base stock has a viscosity from 100 cSt to 2000 cSt at 40.degree.
C. as determined by ASTM D-445; wherein the second base stock is
miscible with the first base stock; and wherein the second base
stock is present in the base stock blend in an amount sufficient to
control film thickness of the lubricant composition.
Embodiment 26
[0256] The method of embodiment 25 wherein, in a mechanical
component having sliding or rolling between contacting surfaces
lubricated with the lubricant composition, film thickness is
controlled by the concentration of the second base stock, and
traction coefficient (Tc) is controlled by concentration of the
first base stock.
Embodiment 27
[0257] The method of embodiment 25 wherein the first base stock is
present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend.
Embodiment 28
[0258] The method of embodiment 25 wherein the first base stock is
present in an amount from 60 to 95 weight percent of the base stock
blend, and the second base stock is present in an amount from 5 to
40 weight percent of the base stock blend.
Embodiment 29
[0259] The method of embodiment 25 wherein the first base stock
comprises a Group I, Group II, Group III, Group IV or Group V base
oil, and the second base stock comprises a Group I, Group II, Group
III, Group IV or Group V base oil.
Embodiment 30
[0260] The method of embodiment 25 wherein the first base stock
comprises a polyalphaolefin (PAO) base oil, and the second base
stock comprises a polyalphaolefin (PAO) base oil or a metallocene
catalyzed polyalphaolefin (PAO) base oil.
Embodiment 31
[0261] The method of embodiment 25 wherein the base stock blend is
present in an amount from 70 to 95 weight percent of the lubricant
composition.
Embodiment 32
[0262] The method of embodiment 25 wherein the lubricant
composition further comprises one or more of a viscosity modifier,
dispersant, detergent, antioxidant, pour point depressant,
corrosion inhibitor, metal deactivator, seal compatibility
additive, anti-foam agent, inhibitor, and anti-rust additive.
Embodiment 33
[0263] The method of embodiment 25 wherein the base stock blend is
a bimodal blend.
Embodiment 34
[0264] The method of embodiment 25 wherein, in the mechanical
component having sliding or rolling between contacting surfaces
lubricated with the lubricant composition, a phase separation or
transition is induced in a mechanical contact zone.
Embodiment 35
[0265] The method of embodiment 25 wherein the lubricant
composition is a finished gear, transmission, engine or industrial
lubricant.
Embodiment 36
[0266] A method for improving wear control, while maintaining or
improving energy efficiency, in a mechanical component having
sliding or rolling between contacting surfaces, said method
comprising using a lubricant composition in the mechanical
component having sliding or rolling between contacting surfaces,
the lubricant composition comprising a base stock blend as a major
component, and at least one lubricant additive, as a minor
component; wherein the base stock blend comprises at least one
first base stock having a viscosity from 1 cSt to 50 cSt at
40.degree. C. as determined by ASTM D-445, and at least one second
base stock having viscosity from 1 cSt to 50 cSt at 40.degree. C.
as determined by ASTM D-445; wherein the first base stock is
different from the second base stock; wherein the first base stock
is present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend; and
wherein the second base stock is miscible with the first base
stock.
Embodiment 37
[0267] A lubricant composition comprising a base stock blend as a
major component, and at least one lubricant additive, as a minor
component; wherein the base stock blend comprises at least one
first base stock having a viscosity from 1 cSt to 50 cSt at
40.degree. C. as determined by ASTM D-445, and at least one second
base stock having viscosity from 1 cSt to 50 cSt at 40.degree. C.
as determined by ASTM D-445; wherein the first base stock is
different from the second base stock; wherein the first base stock
is present in an amount greater than 50 to 95 weight percent of the
base stock blend, and the second base stock is present in an amount
from 5 to less than 50 weight percent of the base stock blend; and
wherein the second base stock is miscible with the first base
stock.
[0268] All patents and patent applications, test procedures (such
as ASTM methods, UL methods, and the like), and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this disclosure and for all
jurisdictions in which such incorporation is permitted.
[0269] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the disclosure
have been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the disclosure. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present disclosure, including all features
which would be treated as equivalents thereof by those skilled in
the art to which the disclosure pertains.
[0270] The present disclosure has been described above with
reference to numerous embodiments and specific examples. Many
variations will suggest themselves to those skilled in this art in
light of the above detailed description. All such obvious
variations are within the full intended scope of the appended
claims.
* * * * *
References